Portable radiography system using a relativistic electron beam

DOEpatents

Hoeberling, R.F.

1987-09-22

A portable radiographic generator is provided with an explosive magnetic flux compression generator producing the high voltage necessary to generate a relativistic electron beam. The relativistic electron beam is provided with target materials which generates the desired radiographic pulse. The magnetic flux compression generator may require at least two conventional explosively driven generators in series to obtain a desired output voltage of at least 1 MV. The cathode and anode configuration of the diode are selected to provide a switching action wherein a high impedance load is presented to the magnetic flux compression generator when the high voltage is being generated, and thereafter switching to a low impedance load to generate the relativistic electron beam. Magnetic flux compression generators can be explosively driven and provided in a relatively compact, portable form for use with the relativistic x-ray equipment. 8 figs.

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

PubMed

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.

Corpuls cpr resuscitation device generates superior emulated flows and pressures than LUCAS II in a mechanical thorax model.

PubMed

Eichhorn, S; Mendoza Garcia, A; Polski, M; Spindler, J; Stroh, A; Heller, M; Lange, R; Krane, M

2017-06-01

The provision of sufficient chest compression is among the most important factors influencing patient survival during cardiopulmonary resuscitation (CPR). One approach to optimize the quality of chest compressions is to use mechanical-resuscitation devices. The aim of this study was to compare a new device for chest compression (corpuls cpr) with an established device (LUCAS II). We used a mechanical thorax model consisting of a chest with variable stiffness and an integrated heart chamber which generated blood flow dependent on the compression depth and waveform. The method of blood-flow generation could be changed between direct cardiac-compression mode and thoracic-pump mode. Different chest-stiffness settings and compression modes were tested to generate various blood-flow profiles. Additionally, an endurance test at high stiffness was performed to measure overall performance and compression consistency. Both resuscitation machines were able to compress the model thorax with a frequency of 100/min and a depth of 5 cm, independent of the chosen chest stiffness. Both devices passed the endurance test without difficulty. The corpuls cpr device was able to generate about 10-40% more blood flow than the LUCAS II device, depending on the model settings. In most scenarios, the corpuls cpr device also generated a higher blood pressure than the LUCAS II. The peak compression forces during CPR were about 30% higher using the corpuls cpr device than with the LUCAS II. In this study, the corpuls cpr device had improved blood flow and pressure outcomes than the LUCAS II device. Further examination in an animal model is required to prove the findings of this preliminary study.

Generation new MP3 data set after compression

NASA Astrophysics Data System (ADS)

Atoum, Mohammed Salem; Almahameed, Mohammad

2016-02-01

The success of audio steganography techniques is to ensure imperceptibility of the embedded secret message in stego file and withstand any form of intentional or un-intentional degradation of secret message (robustness). Crucial to that using digital audio file such as MP3 file, which comes in different compression rate, however research studies have shown that performing steganography in MP3 format after compression is the most suitable one. Unfortunately until now the researchers can not test and implement their algorithm because no standard data set in MP3 file after compression is generated. So this paper focuses to generate standard data set with different compression ratio and different Genre to help researchers to implement their algorithms.

Quasi-isentropic compression using compressed water flow generated by underwater electrical explosion of a wire array

NASA Astrophysics Data System (ADS)

Gurovich, V.; Virozub, A.; Rososhek, A.; Bland, S.; Spielman, R. B.; Krasik, Ya. E.

2018-05-01

A major experimental research area in material equation-of-state today involves the use of off-Hugoniot measurements rather than shock experiments that give only Hugoniot data. There is a wide range of applications using quasi-isentropic compression of matter including the direct measurement of the complete isentrope of materials in a single experiment and minimizing the heating of flyer plates for high-velocity shock measurements. We propose a novel approach to generating quasi-isentropic compression of matter. Using analytical modeling and hydrodynamic simulations, we show that a working fluid composed of compressed water, generated by an underwater electrical explosion of a planar wire array, might be used to efficiently drive the quasi-isentropic compression of a copper target to pressures ˜2 × 1011 Pa without any complex target designs.

Pulse Power Applications of Flux Compression Generators

DTIC Science & Technology

1981-06-01

Characteristics are presented for two different types of explosive driven flux compression generators and a megavolt pulse transformer. Status reports are given for rail gun and plasma focus programs for which the generators serve as power sources.

Investigation of a High Voltage, High Frequency Power Conditioning System for Use with Flux Compression Generators

DTIC Science & Technology

2007-06-01

missouri.edu Abstract The University of Missouri-Columbia is developing a compact pulsed power system to condition the high current signal from a...flux compression generator (FCG) to the high voltage, high frequency signal required for many pulsed power applications. The system consists of a...non-magnetic core, spiral-wound transformer, series exploding wire fuse, and an oscillating mesoband source. The flux compression generator is being

Classifying elementary cellular automata using compressibility, diversity and sensitivity measures

NASA Astrophysics Data System (ADS)

Ninagawa, Shigeru; Adamatzky, Andrew

2014-10-01

An elementary cellular automaton (ECA) is a one-dimensional, synchronous, binary automaton, where each cell update depends on its own state and states of its two closest neighbors. We attempt to uncover correlations between the following measures of ECA behavior: compressibility, sensitivity and diversity. The compressibility of ECA configurations is calculated using the Lempel-Ziv (LZ) compression algorithm LZ78. The sensitivity of ECA rules to initial conditions and perturbations is evaluated using Derrida coefficients. The generative morphological diversity shows how many different neighborhood states are produced from a single nonquiescent cell. We found no significant correlation between sensitivity and compressibility. There is a substantial correlation between generative diversity and compressibility. Using sensitivity, compressibility and diversity, we uncover and characterize novel groupings of rules.

System and method for storing energy

DOEpatents

Yarger, Eric Jay [Rigby, ID; Morrison, John [Butte, MT; Richardson, John Grant [Idaho Falls, ID; Spencer, David Frazer [Idaho Falls, ID; Christiansen, Dale W [Blackfoot, ID

2010-03-30

A self-recharging battery comprising a generator and an energy storage device contained within the battery case. The generator comprises a magnetic structure configured to generate a compressed magnetic field and a coil configured to focus the compressed magnetic field in electrical conductive elements of the coil.

Joint image encryption and compression scheme based on a new hyperchaotic system and curvelet transform

NASA Astrophysics Data System (ADS)

Zhang, Miao; Tong, Xiaojun

2017-07-01

This paper proposes a joint image encryption and compression scheme based on a new hyperchaotic system and curvelet transform. A new five-dimensional hyperchaotic system based on the Rabinovich system is presented. By means of the proposed hyperchaotic system, a new pseudorandom key stream generator is constructed. The algorithm adopts diffusion and confusion structure to perform encryption, which is based on the key stream generator and the proposed hyperchaotic system. The key sequence used for image encryption is relation to plain text. By means of the second generation curvelet transform, run-length coding, and Huffman coding, the image data are compressed. The joint operation of compression and encryption in a single process is performed. The security test results indicate the proposed methods have high security and good compression effect.

SeqCompress: an algorithm for biological sequence compression.

PubMed

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.

Compression of next-generation sequencing quality scores using memetic algorithm

PubMed Central

2014-01-01

Background The exponential growth of next-generation sequencing (NGS) derived DNA data poses great challenges to data storage and transmission. Although many compression algorithms have been proposed for DNA reads in NGS data, few methods are designed specifically to handle the quality scores. Results In this paper we present a memetic algorithm (MA) based NGS quality score data compressor, namely MMQSC. The algorithm extracts raw quality score sequences from FASTQ formatted files, and designs compression codebook using MA based multimodal optimization. The input data is then compressed in a substitutional manner. Experimental results on five representative NGS data sets show that MMQSC obtains higher compression ratio than the other state-of-the-art methods. Particularly, MMQSC is a lossless reference-free compression algorithm, yet obtains an average compression ratio of 22.82% on the experimental data sets. Conclusions The proposed MMQSC compresses NGS quality score data effectively. It can be utilized to improve the overall compression ratio on FASTQ formatted files. PMID:25474747

46 CFR 112.50-7 - Compressed air starting.

Code of Federal Regulations, 2011 CFR

2011-10-01

... AND POWER SYSTEMS Emergency Diesel and Gas Turbine Engine Driven Generator Sets § 112.50-7 Compressed... emergency generator room and a handcranked, diesel-powered air compressor for recharging the air receiver..., and energy storing devices must be in the emergency generator room, except for the main or auxiliary...

46 CFR 112.50-7 - Compressed air starting.

Code of Federal Regulations, 2010 CFR

2010-10-01

... AND POWER SYSTEMS Emergency Diesel and Gas Turbine Engine Driven Generator Sets § 112.50-7 Compressed... emergency generator room and a handcranked, diesel-powered air compressor for recharging the air receiver..., and energy storing devices must be in the emergency generator room, except for the main or auxiliary...

Isentropic compressive wave generator impact pillow and method of making same

DOEpatents

Barker, Lynn M.

1985-01-01

An isentropic compressive wave generator and method of making same. The w generator comprises a disk or flat "pillow" member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

Isentropic compressive wave generator and method of making same

DOEpatents

Barker, L.M.

An isentropic compressive wave generator and method of making same are disclosed. The wave generator comprises a disk or flat pillow member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

A biomechanical evaluation of a cannulated compressive screw for use in fractures of the scaphoid.

PubMed

Rankin, G; Kuschner, S H; Orlando, C; McKellop, H; Brien, W W; Sherman, R

1991-11-01

The compressive force generated by a 3.5 mm ASIF cannulated cancellous screw with a 5 mm head was compared with that generated by a standard 3.5 mm ASIF screw (6 mm head), a 2.7 mm ASIF screw (5 mm head), and a Herbert screw. The screws were evaluated in the laboratory with the use of a custom-designed load washer (transducer) to the maximum compressive force generated by each screw until failure, either by thread stripping or by head migration into the specimen. Testing was done on paired cadaver scaphoids. To minimize the variability that occurs with human bone, and because of the cost and difficulty of obtaining human tissue specimens, a study was also done on polyurethane foam simulated bones. The 3.5 cannulated screw generated greater compressive forces than the Herbert screw but less compression than the 2.7 mm and 3.5 mm ASIF cortical screws. The 3.5 mm cannulated screw offers more rigid internal fixation for scaphoid fractures than the Herbert screw and gives the added advantage of placement over a guide wire.

High-harmonic generation in ZnO driven by self-compressed mid-infrared pulses

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

Gholam-Mirzaei, Shima; Beetar, John E.; Chacon, Alexis

Progress in attosecond science has relied on advancements in few-cycle pulse generation technology and its application to high-order harmonic generation. Traditionally, self-phase modulation in bulk solids has been used for the compression of moderate-energy pulses, additionally exhibiting favorable dispersion properties for mid-infrared (mid-IR) pulses. For this study, we use the anomalous dispersion of Y 3Al 5O 12 (YAG) to self-compress many-cycle pulses from a 50 kHz mid-IR OPA down to produce sub-three-cycle 10 μJ pulses and further use them to generate high-order harmonics in a ZnO crystal. In agreement with theoretical predictions, we observe a boost in the harmonic yieldmore » by a factor of two, and spectral broadening of above-gap harmonics, compared to longer driving pulses. The enhanced yield results from an increase in the intensity for the self-compressed pulses.« less

High-harmonic generation in ZnO driven by self-compressed mid-infrared pulses

DOE PAGES

Gholam-Mirzaei, Shima; Beetar, John E.; Chacon, Alexis; ...

2018-02-20

Progress in attosecond science has relied on advancements in few-cycle pulse generation technology and its application to high-order harmonic generation. Traditionally, self-phase modulation in bulk solids has been used for the compression of moderate-energy pulses, additionally exhibiting favorable dispersion properties for mid-infrared (mid-IR) pulses. For this study, we use the anomalous dispersion of Y 3Al 5O 12 (YAG) to self-compress many-cycle pulses from a 50 kHz mid-IR OPA down to produce sub-three-cycle 10 μJ pulses and further use them to generate high-order harmonics in a ZnO crystal. In agreement with theoretical predictions, we observe a boost in the harmonic yieldmore » by a factor of two, and spectral broadening of above-gap harmonics, compared to longer driving pulses. The enhanced yield results from an increase in the intensity for the self-compressed pulses.« less

Electric power generating plant having direct-coupled steam and compressed-air cycles

DOEpatents

Drost, M.K.

1981-01-07

An electric power generating plant is provided with a Compressed Air Energy Storage (CAES) system which is directly coupled to the steam cycle of the generating plant. The CAES system is charged by the steam boiler during off peak hours, and drives a separate generator during peak load hours. The steam boiler load is thereby levelized throughout an operating day.

Electric power generating plant having direct coupled steam and compressed air cycles

DOEpatents

Drost, Monte K.

1982-01-01

An electric power generating plant is provided with a Compressed Air Energy Storage (CAES) system which is directly coupled to the steam cycle of the generating plant. The CAES system is charged by the steam boiler during off peak hours, and drives a separate generator during peak load hours. The steam boiler load is thereby levelized throughout an operating day.

CSAM: Compressed SAM format.

PubMed

Cánovas, Rodrigo; Moffat, Alistair; Turpin, Andrew

2016-12-15

Next generation sequencing machines produce vast amounts of genomic data. For the data to be useful, it is essential that it can be stored and manipulated efficiently. This work responds to the combined challenge of compressing genomic data, while providing fast access to regions of interest, without necessitating decompression of whole files. We describe CSAM (Compressed SAM format), a compression approach offering lossless and lossy compression for SAM files. The structures and techniques proposed are suitable for representing SAM files, as well as supporting fast access to the compressed information. They generate more compact lossless representations than BAM, which is currently the preferred lossless compressed SAM-equivalent format; and are self-contained, that is, they do not depend on any external resources to compress or decompress SAM files. An implementation is available at https://github.com/rcanovas/libCSAM CONTACT: canovas-ba@lirmm.frSupplementary Information: Supplementary data is available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Performance of a Discrete Wavelet Transform for Compressing Plasma Count Data and its Application to the Fast Plasma Investigation on NASA's Magnetospheric Multiscale Mission

NASA Technical Reports Server (NTRS)

Barrie, Alexander C.; Yeh, Penshu; Dorelli, John C.; Clark, George B.; Paterson, William R.; Adrian, Mark L.; Holland, Matthew P.; Lobell, James V.; Simpson, David G.; Pollock, Craig J.;

Intrinsic Compressive Stress in Polycrystalline Films is Localized at Edges of the Grain Boundaries.

PubMed

Vasco, Enrique; Polop, Celia

2017-12-22

The intrinsic compression that arises in polycrystalline thin films under high atomic mobility conditions has been attributed to the insertion or trapping of adatoms inside grain boundaries. This compression is a consequence of the stress field resulting from imperfections in the solid and causes the thermomechanical fatigue that is estimated to be responsible for 90% of mechanical failures in current devices. We directly measure the local distribution of residual intrinsic stress in polycrystalline thin films on nanometer scales, using a pioneering method based on atomic force microscopy. Our results demonstrate that, at odds with expectations, compression is not generated inside grain boundaries but at the edges of gaps where the boundaries intercept the surface. We describe a model wherein this compressive stress is caused by Mullins-type surface diffusion towards the boundaries, generating a kinetic surface profile different from the mechanical equilibrium profile by the Laplace-Young equation. Where the curvatures of both profiles differ, an intrinsic stress is generated in the form of Laplace pressure. The Srolovitz-type surface diffusion that results from the stress counters the Mullins-type diffusion and stabilizes the kinetic surface profile, giving rise to a steady compression regime. The proposed mechanism of competition between surface diffusions would explain the flux and time dependency of compressive stress in polycrystalline thin films.

Intrinsic Compressive Stress in Polycrystalline Films is Localized at Edges of the Grain Boundaries

NASA Astrophysics Data System (ADS)

Vasco, Enrique; Polop, Celia

2017-12-01

The intrinsic compression that arises in polycrystalline thin films under high atomic mobility conditions has been attributed to the insertion or trapping of adatoms inside grain boundaries. This compression is a consequence of the stress field resulting from imperfections in the solid and causes the thermomechanical fatigue that is estimated to be responsible for 90% of mechanical failures in current devices. We directly measure the local distribution of residual intrinsic stress in polycrystalline thin films on nanometer scales, using a pioneering method based on atomic force microscopy. Our results demonstrate that, at odds with expectations, compression is not generated inside grain boundaries but at the edges of gaps where the boundaries intercept the surface. We describe a model wherein this compressive stress is caused by Mullins-type surface diffusion towards the boundaries, generating a kinetic surface profile different from the mechanical equilibrium profile by the Laplace-Young equation. Where the curvatures of both profiles differ, an intrinsic stress is generated in the form of Laplace pressure. The Srolovitz-type surface diffusion that results from the stress counters the Mullins-type diffusion and stabilizes the kinetic surface profile, giving rise to a steady compression regime. The proposed mechanism of competition between surface diffusions would explain the flux and time dependency of compressive stress in polycrystalline thin films.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Effect of compression of a laser plasma on the generation of harmonics and hard x radiation

NASA Astrophysics Data System (ADS)

Apollonov, V. V.; Derzhavin, S. I.; Kazakov, K. Kh

1993-02-01

A compression of a plasma produced at a conical target by a low-intensity beam (q≲10 GW/cm2) from a CO2 laser has been studied. The effect of this compression on the onset of the parametric instability responsible for the generation of harmonics and of hard x radiation has also been studied. A qualitative interpretation of the results is offered.

High-power picosecond pulses by SPM-induced spectral compression in a fiber amplifier

NASA Astrophysics Data System (ADS)

Schreiber, T.; Liem, A.; Roeser, F.; Zellmer, H.; Tuennermann, A.; Limpert, J.; Deguil-Robin, N.; Manek-Honninger, I.; Salin, F.; Courjaud, A.; Honninger, C.; Mottay, E.

2005-04-01

The fiber based generation of nearly transform-limited 10-ps pulses with 200 kW peak power (97 W average power) based on SPM-induced spectral compression is reported. Efficient second harmonic generation applying this source is also discussed.

Electrophysical properties of water and ice under isentropic compression to megabar pressures

NASA Astrophysics Data System (ADS)

Belov, S. I.; Boriskov, G. V.; Bykov, A. I.; Dolotenko, M. I.; Egorov, N. I.; Korshunov, A. S.; Kudasov, Yu. B.; Makarov, I. V.; Selemir, V. D.; Filippov, A. V.

2017-02-01

The relative permittivity and specific conductivity of water and ice are measured under isentropic compression to pressures above 300 GPa. Compression is initiated by a pulse of an ultrahigh magnetic field generated by an MK-1 magnetocumulative generator. The sample is placed in a coaxial compression chamber with an initial volume of about 40 cm3. The complex relative permittivity was measured by a fast-response reflectometer at a frequency of about 50 MHz. At the compression of water, its relative permittivity increases to ɛ = 350 at a pressure of 8 GPa, then drops sharply to ɛ = 140, and further decreases smoothly. It is shown that measurements of the relative permittivity under isentropic compression make it possible to determine interfaces between ordered and disordered phases of water and ice, as well as to reveal features associated with a change in the activation energy of defects.

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

NASA Astrophysics Data System (ADS)

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.

[Experimental study on spectra of compressed air microwave plasma].

PubMed

Liu, Yong-Xi; Zhang, Gui-Xin; Wang, Qiang; Hou, Ling-Yun

2013-03-01

Using a microwave plasma generator, compressed air microwave plasma was excited under 1 - 5 atm pressures. Under different pressures and different incident microwave power, the emission spectra of compressed air microwave plasma were studied with a spectra measuring system. The results show that continuum is significant at atmospheric pressure and the characteristic will be weakened as the pressure increases. The band spectra intensity will be reduced with the falling of the incident microwave power and the band spectra were still significant. The experimental results are valuable to studying the characteristics of compressed air microwave plasma and the generating conditions of NO active groups.

Thermally generated magnetic fields in laser-driven compressions and explosions

NASA Technical Reports Server (NTRS)

Tidman, D. A.

1975-01-01

The evolution of thermally generated magnetic fields in a plasma undergoing a nearly spherically symmetric adiabatic compression or expansion is calculated. The analysis is applied to obtain approximate results for the development of magnetic fields in laser-driven compression and explosion of a pellet of nuclear fuel. Localized sources, such as those occurring at composition boundaries in structured pellets or at shock fronts, give stronger fields than those deriving from smoothly distributed asymmetries. Although these fields may approach 10 million G in the late stages of compression, this is not expected to present difficulties for the compression process. Assuming ignition of a nuclear explosion occurs, the sources become much stronger, and values of approximately 10 billion G are obtained at tamper boundaries assuming a 20% departure from spherical symmetry during the explosion.

Transport Coefficients in weakly compressible turbulence

NASA Technical Reports Server (NTRS)

Rubinstein, Robert; Erlebacher, Gordon

1996-01-01

A theory of transport coefficients in weakly compressible turbulence is derived by applying Yoshizawa's two-scale direct interaction approximation to the compressible equations of motion linearized about a state of incompressible turbulence. The result is a generalization of the eddy viscosity representation of incompressible turbulence. In addition to the usual incompressible eddy viscosity, the calculation generates eddy diffusivities for entropy and pressure, and an effective bulk viscosity acting on the mean flow. The compressible fluctuations also generate an effective turbulent mean pressure and corrections to the speed of sound. Finally, a prediction unique to Yoshizawa's two-scale approximation is that terms containing gradients of incompressible turbulence quantities also appear in the mean flow equations. The form these terms take is described.

Compressible viscous flows generated by oscillating flexible cylinders

NASA Astrophysics Data System (ADS)

Van Eysden, Cornelis A.; Sader, John E.

2009-01-01

The fluid dynamics of oscillating elastic beams underpin the operation of many modern technological devices ranging from micromechanical sensors to the atomic force microscope. While viscous effects are widely acknowledged to have a strong influence on these dynamics, fluid compressibility is commonly neglected. Here, we theoretically study the three-dimensional flow fields that are generated by the motion of flexible cylinders immersed in viscous compressible fluids and discuss the implications of compressibility in practice. We consider cylinders of circular cross section and flat blades of zero thickness that are executing flexural and torsional oscillations of arbitrary wave number. Exact analytical solutions are derived for these flow fields and their resulting hydrodynamic loads.

Z a Fast Pulsed Power Generator for Ultra-High Magnetic Field Generation

NASA Astrophysics Data System (ADS)

Spielman, R. B.; Stygar, W. A.; Struve, K. W.; Asay, J. R.; Hall, C. A.; Bernard, M. A.; Bailey, J. E.; McDaniel, D. H.

2004-11-01

Advances in fast, pulsed-power technologies have resulted in the development of very high current drivers that have current rise times ~100 ns. The largest such pulsed power driver today is the new Z accelerator located at Sandia National Laboratories in Albuquerque, New Mexico. Z can deliver more than 20 MA with a time-to-peak of 105 ns to low inductance (~1 nH) loads. Such large drivers are capable of directly generating magnetic fields approaching 3 kT in small, 1 cm3 volumes. In addition to direct field generation, Z can be used to compress an applied, axial seed field with a plasma. Flux compression schemes are not new and are, in fact, the basis of all explosive flux-compression generators, but we propose the use of plasma armatures rather than solid, conducting armatures. We present experimental results from the Z accelerator in which magnetic fields of ~2 kT are generated and measured with several diagnostics. Issues such as energy loss in solid conductors and dynamic response of current-carrying conductors to very large magnetic fields are reviewed in context with Z experiments. We describe planned flux-compression experiments that are expected to create the highest-magnitude uniform-field volumes yet attained in the laboratory.

2012 ARPA-E Energy Innovation Summit: Profiling General Compression: A River of Wind

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

Marcus, David; Ingersoll, Eric

The third annual ARPA-E Energy Innovation Summit was held in Washington D.C. in February, 2012. The event brought together key players from across the energy ecosystem - researchers, entrepreneurs, investors, corporate executives, and government officials - to share ideas for developing and deploying the next generation of energy technologies. A few videos were selected for showing during the Summit to attendees. These 'performer videos' highlight innovative research that is ongoing and related to the main topics of the Summit's sessions. Featured in this video are David Marcus, Founder of General Compression, and Eric Ingersoll, CEO of General Compression. General Compression,more » with the help of ARPA-E funding, has created an advanced air compression process which can store and release more than a weeks worth of the energy generated by wind turbines.« less

2012 ARPA-E Energy Innovation Summit: Profiling General Compression: A River of Wind

ScienceCinema

Marcus, David; Ingersoll, Eric

2018-05-30

The third annual ARPA-E Energy Innovation Summit was held in Washington D.C. in February, 2012. The event brought together key players from across the energy ecosystem - researchers, entrepreneurs, investors, corporate executives, and government officials - to share ideas for developing and deploying the next generation of energy technologies. A few videos were selected for showing during the Summit to attendees. These 'performer videos' highlight innovative research that is ongoing and related to the main topics of the Summit's sessions. Featured in this video are David Marcus, Founder of General Compression, and Eric Ingersoll, CEO of General Compression. General Compression, with the help of ARPA-E funding, has created an advanced air compression process which can store and release more than a weeks worth of the energy generated by wind turbines.

Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

NASA Astrophysics Data System (ADS)

Bowen, Trevor A.; Badman, Samuel; Hellinger, Petr; Bale, Stuart D.

2018-02-01

Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfvén wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfvén waves.

Toward a Better Compression for DNA Sequences Using Huffman Encoding

PubMed Central

Almarri, Badar; Al Yami, Sultan; Huang, Chun-Hsi

2017-01-01

Abstract Due to the significant amount of DNA data that are being generated by next-generation sequencing machines for genomes of lengths ranging from megabases to gigabases, there is an increasing need to compress such data to a less space and a faster transmission. Different implementations of Huffman encoding incorporating the characteristics of DNA sequences prove to better compress DNA data. These implementations center on the concepts of selecting frequent repeats so as to force a skewed Huffman tree, as well as the construction of multiple Huffman trees when encoding. The implementations demonstrate improvements on the compression ratios for five genomes with lengths ranging from 5 to 50 Mbp, compared with the standard Huffman tree algorithm. The research hence suggests an improvement on all such DNA sequence compression algorithms that use the conventional Huffman encoding. The research suggests an improvement on all DNA sequence compression algorithms that use the conventional Huffman encoding. Accompanying software is publicly available (AL-Okaily, 2016). PMID:27960065

Toward a Better Compression for DNA Sequences Using Huffman Encoding.

PubMed

Al-Okaily, Anas; Almarri, Badar; Al Yami, Sultan; Huang, Chun-Hsi

2017-04-01

Due to the significant amount of DNA data that are being generated by next-generation sequencing machines for genomes of lengths ranging from megabases to gigabases, there is an increasing need to compress such data to a less space and a faster transmission. Different implementations of Huffman encoding incorporating the characteristics of DNA sequences prove to better compress DNA data. These implementations center on the concepts of selecting frequent repeats so as to force a skewed Huffman tree, as well as the construction of multiple Huffman trees when encoding. The implementations demonstrate improvements on the compression ratios for five genomes with lengths ranging from 5 to 50 Mbp, compared with the standard Huffman tree algorithm. The research hence suggests an improvement on all such DNA sequence compression algorithms that use the conventional Huffman encoding. The research suggests an improvement on all DNA sequence compression algorithms that use the conventional Huffman encoding. Accompanying software is publicly available (AL-Okaily, 2016 ).

Developing JSequitur to Study the Hierarchical Structure of Biological Sequences in a Grammatical Inference Framework of String Compression Algorithms.

PubMed

Galbadrakh, Bulgan; Lee, Kyung-Eun; Park, Hyun-Seok

2012-12-01

Grammatical inference methods are expected to find grammatical structures hidden in biological sequences. One hopes that studies of grammar serve as an appropriate tool for theory formation. Thus, we have developed JSequitur for automatically generating the grammatical structure of biological sequences in an inference framework of string compression algorithms. Our original motivation was to find any grammatical traits of several cancer genes that can be detected by string compression algorithms. Through this research, we could not find any meaningful unique traits of the cancer genes yet, but we could observe some interesting traits in regards to the relationship among gene length, similarity of sequences, the patterns of the generated grammar, and compression rate.

Biomechanical Comparison of External Fixation and Compression Screws for Transverse Tarsal Joint Arthrodesis.

PubMed

Latt, L Daniel; Glisson, Richard R; Adams, Samuel B; Schuh, Reinhard; Narron, John A; Easley, Mark E

2015-10-01

Transverse tarsal joint arthrodesis is commonly performed in the operative treatment of hindfoot arthritis and acquired flatfoot deformity. While fixation is typically achieved using screws, failure to obtain and maintain joint compression sometimes occurs, potentially leading to nonunion. External fixation is an alternate method of achieving arthrodesis site compression and has the advantage of allowing postoperative compression adjustment when necessary. However, its performance relative to standard screw fixation has not been quantified in this application. We hypothesized that external fixation could provide transverse tarsal joint compression exceeding that possible with screw fixation. Transverse tarsal joint fixation was performed sequentially, first with a circular external fixator and then with compression screws, on 9 fresh-frozen cadaveric legs. The external fixator was attached in abutting rings fixed to the tibia and the hindfoot and a third anterior ring parallel to the hindfoot ring using transverse wires and half-pins in the tibial diaphysis, calcaneus, and metatarsals. Screw fixation comprised two 4.3 mm headless compression screws traversing the talonavicular joint and 1 across the calcaneocuboid joint. Compressive forces generated during incremental fixator foot ring displacement to 20 mm and incremental screw tightening were measured using a custom-fabricated instrumented miniature external fixator spanning the transverse tarsal joint. The maximum compressive force generated by the external fixator averaged 186% of that produced by the screws (range, 104%-391%). Fixator compression surpassed that obtainable with screws at 12 mm of ring displacement and decreased when the tibial ring was detached. No correlation was found between bone density and the compressive force achievable by either fusion method. The compression across the transverse tarsal joint that can be obtained with a circular external fixator including a tibial ring exceeds that which can be obtained with 3 headless compression screws. Screw and external fixator performance did not correlate with bone mineral density. This study supports the use of external fixation as an alternative method of generating compression to help stimulate fusion across the transverse tarsal joints. The findings provide biomechanical evidence to support the use of external fixation as a viable option in transverse tarsal joint fusion cases in which screw fixation has failed or is anticipated to be inadequate due to suboptimal bone quality. © The Author(s) 2015.

Large-scale vortices in compressible turbulent medium with the magnetic field

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.; Dimitrov, B. G.

1990-08-01

An averaged equation which describes the large scale vortices and Alfven waves generation in a compressible helical turbulent medium with a constant magnetic field is presented. The presence of the magnetic field leads to anisotropization of the vortex generation. Possible applications of the anisotropic vortex dynamo effect are accretion disks of compact objects.

Cosmological Particle Data Compression in Practice

NASA Astrophysics Data System (ADS)

Zeyen, M.; Ahrens, J.; Hagen, H.; Heitmann, K.; Habib, S.

2017-12-01

In cosmological simulations trillions of particles are handled and several terabytes of unstructured particle data are generated in each time step. Transferring this data directly from memory to disk in an uncompressed way results in a massive load on I/O and storage systems. Hence, one goal of domain scientists is to compress the data before storing it to disk while minimizing the loss of information. To prevent reading back uncompressed data from disk, this can be done in an in-situ process. Since the simulation continuously generates data, the available time for the compression of one time step is limited. Therefore, the evaluation of compression techniques has shifted from only focusing on compression rates to include run-times and scalability.In recent years several compression techniques for cosmological data have become available. These techniques can be either lossy or lossless, depending on the technique. For both cases, this study aims to evaluate and compare the state of the art compression techniques for unstructured particle data. This study focuses on the techniques available in the Blosc framework with its multi-threading support, the XZ Utils toolkit with the LZMA algorithm that achieves high compression rates, and the widespread FPZIP and ZFP methods for lossy compressions.For the investigated compression techniques, quantitative performance indicators such as compression rates, run-time/throughput, and reconstruction errors are measured. Based on these factors, this study offers a comprehensive analysis of the individual techniques and discusses their applicability for in-situ compression. In addition, domain specific measures are evaluated on the reconstructed data sets, and the relative error rates and statistical properties are analyzed and compared. Based on this study future challenges and directions in the compression of unstructured cosmological particle data were identified.

Combined rankine and vapor compression cycles

DOEpatents

Radcliff, Thomas D.; Biederman, Bruce P.; Brasz, Joost J.

2005-04-19

An organic rankine cycle system is combined with a vapor compression cycle system with the turbine generator of the organic rankine cycle generating the power necessary to operate the motor of the refrigerant compressor. The vapor compression cycle is applied with its evaporator cooling the inlet air into a gas turbine, and the organic rankine cycle is applied to receive heat from a gas turbine exhaust to heat its boiler within one embodiment, a common condenser is used for the organic rankine cycle and the vapor compression cycle, with a common refrigerant, R-245a being circulated within both systems. In another embodiment, the turbine driven generator has a common shaft connected to the compressor to thereby eliminate the need for a separate motor to drive the compressor. In another embodiment, an organic rankine cycle system is applied to an internal combustion engine to cool the fluids thereof, and the turbo charged air is cooled first by the organic rankine cycle system and then by an air conditioner prior to passing into the intake of the engine.

Fast modeling of flux trapping cascaded explosively driven magnetic flux compression generators.

PubMed

Wang, Yuwei; Zhang, Jiande; Chen, Dongqun; Cao, Shengguang; Li, Da; Liu, Chebo

2013-01-01

To predict the performance of flux trapping cascaded flux compression generators, a calculation model based on an equivalent circuit is investigated. The system circuit is analyzed according to its operation characteristics in different steps. Flux conservation coefficients are added to the driving terms of circuit differential equations to account for intrinsic flux losses. To calculate the currents in the circuit by solving the circuit equations, a simple zero-dimensional model is used to calculate the time-varying inductance and dc resistance of the generator. Then a fast computer code is programmed based on this calculation model. As an example, a two-staged flux trapping generator is simulated by using this computer code. Good agreements are achieved by comparing the simulation results with the measurements. Furthermore, it is obvious that this fast calculation model can be easily applied to predict performances of other flux trapping cascaded flux compression generators with complex structures such as conical stator or conical armature sections and so on for design purpose.

Thermodynamic Analysis of a Rankine Cycle Powered Vapor Compression Ice Maker Using Solar Energy

PubMed Central

Hu, Bing; Bu, Xianbiao; Ma, Weibin

2014-01-01

To develop the organic Rankine-vapor compression ice maker driven by solar energy, a thermodynamic model was developed and the effects of generation temperature, condensation temperature, and working fluid types on the system performance were analyzed. The results show that the cooling power per square meter collector and ice production per square meter collector per day depend largely on generation temperature and condensation temperature and they increase firstly and then decrease with increasing generation temperature. For every working fluid there is an optimal generation temperature at which organic Rankine efficiency achieves the maximum value. The cooling power per square meter collector and ice production per square meter collector per day are, respectively, 126.44 W m−2 and 7.61 kg m−2 day−1 at the generation temperature of 140°C for working fluid of R245fa, which demonstrates the feasibility of organic Rankine cycle powered vapor compression ice maker. PMID:25202735

Fast electron microscopy via compressive sensing

DOEpatents

Larson, Kurt W; Anderson, Hyrum S; Wheeler, Jason W

2014-12-09

Various technologies described herein pertain to compressive sensing electron microscopy. A compressive sensing electron microscope includes a multi-beam generator and a detector. The multi-beam generator emits a sequence of electron patterns over time. Each of the electron patterns can include a plurality of electron beams, where the plurality of electron beams is configured to impart a spatially varying electron density on a sample. Further, the spatially varying electron density varies between each of the electron patterns in the sequence. Moreover, the detector collects signals respectively corresponding to interactions between the sample and each of the electron patterns in the sequence.

Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

NASA Technical Reports Server (NTRS)

Li, Lihua; Coon, Michael; McLinden, Matthew

2013-01-01

Pulse compression has been widely used in radars so that low-power, long RF pulses can be transmitted, rather than a highpower short pulse. Pulse compression radars offer a number of advantages over high-power short pulsed radars, such as no need of high-power RF circuitry, no need of high-voltage electronics, compact size and light weight, better range resolution, and better reliability. However, range sidelobe associated with pulse compression has prevented the use of this technique on spaceborne radars since surface returns detected by range sidelobes may mask the returns from a nearby weak cloud or precipitation particles. Research on adaptive pulse compression was carried out utilizing a field-programmable gate array (FPGA) waveform generation board and a radar transceiver simulator. The results have shown significant improvements in pulse compression sidelobe performance. Microwave and millimeter-wave radars present many technological challenges for Earth and planetary science applications. The traditional tube-based radars use high-voltage power supply/modulators and high-power RF transmitters; therefore, these radars usually have large size, heavy weight, and reliability issues for space and airborne platforms. Pulse compression technology has provided a path toward meeting many of these radar challenges. Recent advances in digital waveform generation, digital receivers, and solid-state power amplifiers have opened a new era for applying pulse compression to the development of compact and high-performance airborne and spaceborne remote sensing radars. The primary objective of this innovative effort is to develop and test a new pulse compression technique to achieve ultrarange sidelobes so that this technique can be applied to spaceborne, airborne, and ground-based remote sensing radars to meet future science requirements. By using digital waveform generation, digital receiver, and solid-state power amplifier technologies, this improved pulse compression technique could bring significant impact on future radar development. The novel feature of this innovation is the non-linear FM (NLFM) waveform design. The traditional linear FM has the limit (-20 log BT -3 dB) for achieving ultra-low-range sidelobe in pulse compression. For this study, a different combination of 20- or 40-microsecond chirp pulse width and 2- or 4-MHz chirp bandwidth was used. These are typical operational parameters for airborne or spaceborne weather radars. The NLFM waveform design was then implemented on a FPGA board to generate a real chirp signal, which was then sent to the radar transceiver simulator. The final results have shown significant improvement on sidelobe performance compared to that obtained using a traditional linear FM chirp.

CARGO: effective format-free compressed storage of genomic information

PubMed Central

Roguski, Łukasz; Ribeca, Paolo

2016-01-01

The recent super-exponential growth in the amount of sequencing data generated worldwide has put techniques for compressed storage into the focus. Most available solutions, however, are strictly tied to specific bioinformatics formats, sometimes inheriting from them suboptimal design choices; this hinders flexible and effective data sharing. Here, we present CARGO (Compressed ARchiving for GenOmics), a high-level framework to automatically generate software systems optimized for the compressed storage of arbitrary types of large genomic data collections. Straightforward applications of our approach to FASTQ and SAM archives require a few lines of code, produce solutions that match and sometimes outperform specialized format-tailored compressors and scale well to multi-TB datasets. All CARGO software components can be freely downloaded for academic and non-commercial use from http://bio-cargo.sourceforge.net. PMID:27131376

Two-stage optical parametric chirped-pulse amplifier using sub-nanosecond pump pulse generated by stimulated Brillouin scattering compression

NASA Astrophysics Data System (ADS)

Ogino, Jumpei; Miyamoto, Sho; Matsuyama, Takahiro; Sueda, Keiichi; Yoshida, Hidetsugu; Tsubakimoto, Koji; Miyanaga, Noriaki

2014-12-01

We demonstrate optical parametric chirped-pulse amplification (OPCPA) based on two-beam pumping, using sub-nanosecond pulses generated by stimulated Brillouin scattering compression. Seed pulse energy, duration, and center wavelength were 5 nJ, 220 ps, and ˜1065 nm, respectively. The 532 nm pulse from a Q-switched Nd:YAG laser was compressed to ˜400 ps in heavy fluorocarbon FC-40 liquid. Stacking of two time-delayed pump pulses reduced the amplifier gain fluctuation. Using a walk-off-compensated two-stage OPCPA at a pump energy of 34 mJ, a total gain of 1.6 × 105 was obtained, yielding an output energy of 0.8 mJ. The amplified chirped pulse was compressed to 97 fs.

Elucidating the Role of Compression Waves and Impact Duration for Generating mild Traumatic Brain Injury in Rats

PubMed Central

Lucke-Wold, Brandon P.; Phillips, Michael; Turner, Ryan C.; Logsdon, Aric F.; Smith, Kelly E.; Huber, Jason D.; Rosen, Charles L.; Regele, Jonathan D.

2016-01-01

3 million concussions occur each year in the United States. The mechanisms linking acute injury to chronic deficits are poorly understood. Mild traumatic brain injury has been described clinically in terms of acute functional deficits, but the underlying histopathologic changes that occur are relatively unknown due to limited high-function imaging modalities. In order to improve our understanding of acute injury mechanisms, appropriately designed preclinical models must be utilized. The clinical relevance of compression wave injury models revolves around the ability to produce consistent histopathologic deficits. Repetitive mild traumatic brain injuries activate similar neuroinflammatory cascades, cell death markers, and increases in amyloid precursor protein in both humans and rodents. Humans however infrequently succumb to mild traumatic brain injuries and therefore the intensity and magnitude of impacts must be inferred. Understanding compression wave properties and mechanical loading could help link the histopathologic deficits seen in rodents to what might be happening in human brains following repetitive concussions. Advances in mathematical and computer modeling can help characterize the wave properties generated by the compression wave model. While this concept of linking duration and intensity of impact to subsequent histopathologic deficits makes sense, numerical modeling of compression waves has not been performed in this context. In this collaborative interdisciplinary work, numerical simulations were performed to study the creation of compression waves in our experimental model. This work was conducted in conjunction with a repetitive compression wave injury paradigm in rats in order to better understand how the wave generation correlates with validated histopathologic deficits. PMID:27880054

Symmetric and asymmetric hybrid cryptosystem based on compressive sensing and computer generated holography

NASA Astrophysics Data System (ADS)

Ma, Lihong; Jin, Weimin

2018-01-01

A novel symmetric and asymmetric hybrid optical cryptosystem is proposed based on compressive sensing combined with computer generated holography. In this method there are six encryption keys, among which two decryption phase masks are different from the two random phase masks used in the encryption process. Therefore, the encryption system has the feature of both symmetric and asymmetric cryptography. On the other hand, because computer generated holography can flexibly digitalize the encrypted information and compressive sensing can significantly reduce data volume, what is more, the final encryption image is real function by phase truncation, the method favors the storage and transmission of the encryption data. The experimental results demonstrate that the proposed encryption scheme boosts the security and has high robustness against noise and occlusion attacks.

Electromagnetic ion cyclotron waves stimulated by modest magnetospheric compressions

NASA Technical Reports Server (NTRS)

Anderson, B. J.; Hamilton, D. C.

1993-01-01

AMPTE/CCE magnetic field and particle data are used to test the suggestion that increased hot proton temperature anisotropy resulting from convection during magnetospheric compression is responsible for the enhancement in Pc 1 emission via generation of electromagnetic ion cyclotron (EMIC) waves in the dayside outer equatorial magnetosphere. The relative increase in magnetic field is used to gauge the strength of the compression, and an image dipole model is used to estimate the motion of the plasma during compression. Proton data are used to analyze the evolution of the proton distribution and the corresponding changes in EMIC wave activity expected during the compression. It is suggested that enhancements in dynamic pressure pump the energetic proton distributions in the outer magnetosphere, driving EMIC waves. Waves are expected to be generated most readily close to the magnetopause, and transient pressure pulses may be associated with bursts of EMIC waves, which would be observed on the ground in association with ionospheric transient signatures.

Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

NASA Astrophysics Data System (ADS)

Olbinado, Margie P.; Cantelli, Valentina; Mathon, Olivier; Pascarelli, Sakura; Grenzer, Joerg; Pelka, Alexander; Roedel, Melanie; Prencipe, Irene; Laso Garcia, Alejandro; Helbig, Uwe; Kraus, Dominik; Schramm, Ulrich; Cowan, Tom; Scheel, Mario; Pradel, Pierre; De Resseguier, Thibaut; Rack, Alexander

2018-02-01

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

Skin blood flow with elastic compressive extravehicular activity space suit.

PubMed

Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu; Hargens, Alan R

2003-10-01

During extravehicular activity (EVA), current space suits are pressurized with 100% oxygen at approximately 222 mmHg. A tight elastic garment, or mechanical counter pressure (MCP) suit that generates pressure by compression, may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with negative ambient pressure with an MCP sleeve. The MCP glove and sleeve generated pressures similar to the current space suit. MCP remained constant during negative pressure due to unchanged elasticity of the material. Decreased skin capillary blood flow and temperature during MCP compression was counteracted by greater negative pressure or a smaller pressure differential.

Intelligent transportation systems data compression using wavelet decomposition technique.

DOT National Transportation Integrated Search

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....

Compression of next-generation sequencing reads aided by highly efficient de novo assembly

PubMed Central

Jones, Daniel C.; Ruzzo, Walter L.; Peng, Xinxia

2012-01-01

We present Quip, a lossless compression algorithm for next-generation sequencing data in the FASTQ and SAM/BAM formats. In addition to implementing reference-based compression, we have developed, to our knowledge, the first assembly-based compressor, using a novel de novo assembly algorithm. A probabilistic data structure is used to dramatically reduce the memory required by traditional de Bruijn graph assemblers, allowing millions of reads to be assembled very efficiently. Read sequences are then stored as positions within the assembled contigs. This is combined with statistical compression of read identifiers, quality scores, alignment information and sequences, effectively collapsing very large data sets to <15% of their original size with no loss of information. Availability: Quip is freely available under the 3-clause BSD license from http://cs.washington.edu/homes/dcjones/quip. PMID:22904078

Compressible magma/mantle dynamics: 3-D, adaptive simulations in ASPECT

NASA Astrophysics Data System (ADS)

Dannberg, Juliane; Heister, Timo

2016-12-01

Melt generation and migration are an important link between surface processes and the thermal and chemical evolution of the Earth's interior. However, their vastly different timescales make it difficult to study mantle convection and melt migration in a unified framework, especially for 3-D global models. And although experiments suggest an increase in melt volume of up to 20 per cent from the depth of melt generation to the surface, previous computations have neglected the individual compressibilities of the solid and the fluid phase. Here, we describe our extension of the finite element mantle convection code ASPECT that adds melt generation and migration. We use the original compressible formulation of the McKenzie equations, augmented by an equation for the conservation of energy. Applying adaptive mesh refinement to this type of problems is particularly advantageous, as the resolution can be increased in areas where melt is present and viscosity gradients are high, whereas a lower resolution is sufficient in regions without melt. Together with a high-performance, massively parallel implementation, this allows for high-resolution, 3-D, compressible, global mantle convection simulations coupled with melt migration. We evaluate the functionality and potential of this method using a series of benchmarks and model setups, compare results of the compressible and incompressible formulation, and show the effectiveness of adaptive mesh refinement when applied to melt migration. Our model of magma dynamics provides a framework for modelling processes on different scales and investigating links between processes occurring in the deep mantle and melt generation and migration. This approach could prove particularly useful applied to modelling the generation of komatiites or other melts originating in greater depths. The implementation is available in the Open Source ASPECT repository.

A High-Performance Lossless Compression Scheme for EEG Signals Using Wavelet Transform and Neural Network Predictors

PubMed Central

Sriraam, N.

2012-01-01

Developments of new classes of efficient compression algorithms, software systems, and hardware for data intensive applications in today's digital health care systems provide timely and meaningful solutions in response to exponentially growing patient information data complexity and associated analysis requirements. Of the different 1D medical signals, electroencephalography (EEG) data is of great importance to the neurologist for detecting brain-related disorders. The volume of digitized EEG data generated and preserved for future reference exceeds the capacity of recent developments in digital storage and communication media and hence there is a need for an efficient compression system. This paper presents a new and efficient high performance lossless EEG compression using wavelet transform and neural network predictors. The coefficients generated from the EEG signal by integer wavelet transform are used to train the neural network predictors. The error residues are further encoded using a combinational entropy encoder, Lempel-Ziv-arithmetic encoder. Also a new context-based error modeling is also investigated to improve the compression efficiency. A compression ratio of 2.99 (with compression efficiency of 67%) is achieved with the proposed scheme with less encoding time thereby providing diagnostic reliability for lossless transmission as well as recovery of EEG signals for telemedicine applications. PMID:22489238

A high-performance lossless compression scheme for EEG signals using wavelet transform and neural network predictors.

PubMed

Sriraam, N

2012-01-01

Developments of new classes of efficient compression algorithms, software systems, and hardware for data intensive applications in today's digital health care systems provide timely and meaningful solutions in response to exponentially growing patient information data complexity and associated analysis requirements. Of the different 1D medical signals, electroencephalography (EEG) data is of great importance to the neurologist for detecting brain-related disorders. The volume of digitized EEG data generated and preserved for future reference exceeds the capacity of recent developments in digital storage and communication media and hence there is a need for an efficient compression system. This paper presents a new and efficient high performance lossless EEG compression using wavelet transform and neural network predictors. The coefficients generated from the EEG signal by integer wavelet transform are used to train the neural network predictors. The error residues are further encoded using a combinational entropy encoder, Lempel-Ziv-arithmetic encoder. Also a new context-based error modeling is also investigated to improve the compression efficiency. A compression ratio of 2.99 (with compression efficiency of 67%) is achieved with the proposed scheme with less encoding time thereby providing diagnostic reliability for lossless transmission as well as recovery of EEG signals for telemedicine applications.

Observational Signatures of Parametric Instability at 1AU

NASA Astrophysics Data System (ADS)

Bowen, T. A.; Bale, S. D.; Badman, S.

2017-12-01

Observations and simulations of inertial compressive turbulence in the solar wind are characterized by density structures anti-correlated with magnetic fluctuations parallel to the mean field. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures (PBS), kinetic ion acoustic waves, as well as the MHD slow mode. Recent work, specifically Verscharen et al. (2017), has highlighted the unexpected fluid like nature of the solar wind. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggests the presence of a driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the parametric instability, in which large amplitude Alfvenic fluctuations decay into parallel propagating compressive waves. This work employs 10 years of WIND observations in order to test the parametric decay process as a source of compressive waves in the solar wind through comparing collisionless damping rates of compressive fluctuations with growth rates of the parametric instability. Preliminary results suggest that generation of compressive waves through parametric decay is overdamped at 1 AU. However, the higher parametric decay rates expected in the inner heliosphere likely allow for growth of the slow mode-the remnants of which could explain density fluctuations observed at 1AU.

LagLoc - a new surgical technique for locking plate systems.

PubMed

Triana, Miguel; Gueorguiev, Boyko; Sommer, Christoph; Stoffel, Karl; Agarwal, Yash; Zderic, Ivan; Helfen, Tobias; Krieg, James C; Krause, Fabian; Knobe, Matthias; Richards, R Geoff; Lenz, Mark

2018-06-19

Treatment of oblique and spiral fractures remains challenging. The aim of this study was to introduce and investigate the new LagLoc technique for locked plating with generation of interfragmentary compression, combining the advantages of lag-screw and locking-head-screw techniques. Oblique fracture was simulated in artificial diaphyseal bones, assigned to three groups for plating with a 7-hole locking compression plate. Group I was plated with three locking screws in holes 1, 4 and 7. The central screw crossed the fracture line. In group II the central hole was occupied with a lag screw perpendicular to fracture line. Group III was instrumented applying the LagLoc technique as follows. Hole 4 was predrilled perpendicularly to the plate, followed by overdrilling of the near cortex and insertion of a locking screw whose head was covered by a holding sleeve to prevent temporarily the locking in the plate hole and generate interfragmentary compression. Subsequently, the screw head was released and locked in the plate hole. Holes 1 and 7 were occupied with locking screws. Interfragmentary compression in the fracture gap was measured using pressure sensors. All screws in the three groups were tightened with 4Nm torque. Interfragmentary compression in group I (167 ± 25N) was significantly lower in comparison to groups II (431 ± 21N) and III (379 ± 59N), p≤0.005. The difference in compression between groups II and III remained not significant (p = 0.999). The new LagLoc technique offers an alternative tool to generate interfragmentary compression with the application of locking plates by combining the biomechanical advantages of lag screw and locking screw fixations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Three-dimensional direct observation of Gouy phase shift in a terajet produced by a dielectric cuboid

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

Nguyen Pham, Hai Huy, E-mail: haihuynguyenpham135@s.ee.es.osaka-u.ac.jp; Hisatake, Shintaro, E-mail: hisatake@ee.es.osaka-u.ac.jp; Nagatsuma, Tadao, E-mail: nagatuma@ee.es.osaka-u.ac.jp

2016-05-09

The generation of the terajet at the terahertz (THz) frequency with the capability of subwavelength beam-compression has been attracting increasing research interest, as did the generation of the nanojet at the optical frequency. In particular, a terajet generated from a dielectric cuboid was not previously studied experimentally in the THz region. We here experimentally demonstrate three-dimensional visualizations and characterization of a terajet generated from a dielectric cuboid with a refractive index of n = 1.46 at 125 GHz. The subwavelength compressed beam and the Gouy phase shift phenomena of the terajet are directly observed. It is also found out that a calculation modelmore » of Gouy phase shift based on focused Gaussian beam by a lens cannot explain the Gouy phase shift of compressed beam by the terajet. The intensity enhancement of about 7.4 dB and full width at half maximum of 0.6λ are obtained at the distance 0.5λ from the cuboid.« less

The Effect of a Third Generation Hemostatic Dressing in a Subclavian Artery and Vein Transection Porcine Model

DTIC Science & Technology

2014-04-01

The MSD is comprised of a syringe applicator filled with compressed chitosan coated sponges which are delivered into the wound at the site of the...transmitted effectively to the deep subclavian vessels to stop hemorrhage. As a result of their non-compressible nature and paucity of effective field...followed by three minutes of compression to the packed dressing. The mini- sponge dressing (MSD) is a novel product that utilizes compressed, chitosan

Effects of Compression, Staging, and Braid Angle on Braided Rope Seal Performance

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H.; Adams, Michael L.

2006-01-01

This viewgraph presentation describes the effects of compression, staging and braid angle on braided rope seals. The contents include: 1) Test Fixture Schematics; 2) Comparison of Hybrid Seal Braid Architecture; 3) Residual Interference After Compression Cycling; 4) Effect of Compression, Braid, and Staging on Seal Flow; 5) Effect of Staging on Seal Pressure Drop; 6) Three Stag Seal Durability; 7) P&W Turbine Vane Seal Requirements; and 8) Next Generation Fighter F-22 P&W F119 Engines.

Architecture for one-shot compressive imaging using computer-generated holograms.

PubMed

Macfaden, Alexander J; Kindness, Stephen J; Wilkinson, Timothy D

2016-09-10

We propose a synchronous implementation of compressive imaging. This method is mathematically equivalent to prevailing sequential methods, but uses a static holographic optical element to create a spatially distributed spot array from which the image can be reconstructed with an instantaneous measurement. We present the holographic design requirements and demonstrate experimentally that the linear algebra of compressed imaging can be implemented with this technique. We believe this technique can be integrated with optical metasurfaces, which will allow the development of new compressive sensing methods.

Elucidation of Compression-Induced Surface Crystallization in Amorphous Tablets Using Sum Frequency Generation (SFG) Microscopy.

PubMed

Mah, Pei T; Novakovic, Dunja; Saarinen, Jukka; Van Landeghem, Stijn; Peltonen, Leena; Laaksonen, Timo; Isomäki, Antti; Strachan, Clare J

2017-05-01

To investigate the effect of compression on the crystallization behavior in amorphous tablets using sum frequency generation (SFG) microscopy imaging and more established analytical methods. Tablets containing neat amorphous griseofulvin with/without excipients (silica, hydroxypropyl methylcellulose acetate succinate (HPMCAS), microcrystalline cellulose (MCC) and polyethylene glycol (PEG)) were prepared. They were analyzed upon preparation and storage using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM) and SFG microscopy. Compression-induced crystallization occurred predominantly on the surface of the neat amorphous griseofulvin tablets, with minimal crystallinity being detected in the core of the tablets. The presence of various types of excipients was not able to mitigate the compression-induced surface crystallization of the amorphous griseofulvin tablets. However, the excipients affected the crystallization rate of amorphous griseofulvin in the core of the tablet upon compression and storage. SFG microscopy can be used in combination with ATR-FTIR spectroscopy and SEM to understand the crystallization behaviour of amorphous tablets upon compression and storage. When selecting excipients for amorphous formulations, it is important to consider the effect of the excipients on the physical stability of the amorphous formulations.

Applications of wavelet-based compression to multidimensional Earth science data

NASA Technical Reports Server (NTRS)

Bradley, Jonathan N.; Brislawn, Christopher M.

1993-01-01

A data compression algorithm involving vector quantization (VQ) and the discrete wavelet transform (DWT) is applied to two different types of multidimensional digital earth-science data. The algorithms (WVQ) is optimized for each particular application through an optimization procedure that assigns VQ parameters to the wavelet transform subbands subject to constraints on compression ratio and encoding complexity. Preliminary results of compressing global ocean model data generated on a Thinking Machines CM-200 supercomputer are presented. The WVQ scheme is used in both a predictive and nonpredictive mode. Parameters generated by the optimization algorithm are reported, as are signal-to-noise (SNR) measurements of actual quantized data. The problem of extrapolating hydrodynamic variables across the continental landmasses in order to compute the DWT on a rectangular grid is discussed. Results are also presented for compressing Landsat TM 7-band data using the WVQ scheme. The formulation of the optimization problem is presented along with SNR measurements of actual quantized data. Postprocessing applications are considered in which the seven spectral bands are clustered into 256 clusters using a k-means algorithm and analyzed using the Los Alamos multispectral data analysis program, SPECTRUM, both before and after being compressed using the WVQ program.

Pulse Compression Techniques for Laser Generated Ultrasound

NASA Technical Reports Server (NTRS)

Anastasi, R. F.; Madaras, E. I.

1999-01-01

Laser generated ultrasound for nondestructive evaluation has an optical power density limit due to rapid high heating that causes material damage. This damage threshold limits the generated ultrasound amplitude, which impacts nondestructive evaluation inspection capability. To increase ultrasound signal levels and improve the ultrasound signal-to-noise ratio without exceeding laser power limitations, it is possible to use pulse compression techniques. The approach illustrated here uses a 150mW laser-diode modulated with a pseudo-random sequence and signal correlation. Results demonstrate the successful generation of ultrasonic bulk waves in aluminum and graphite-epoxy composite materials using a modulated low-power laser diode and illustrate ultrasound bandwidth control.

Biomechanical evaluation of a second generation headless compression screw for ankle arthrodesis in a cadaver model.

PubMed

Somberg, Andrew Max; Whiteside, William K; Nilssen, Erik; Murawski, Daniel; Liu, Wei

2016-03-01

Many types of screws, plates, and strut grafts have been utilized for ankle arthrodesis. Biomechanical testing has shown that these constructs can have variable stiffness. More recently, headless compression screws have emerged as an evolving method of achieving compression in various applications but there is limited literature regarding ankle arthrodesis. The aim of this study was to determine the biomechanical stability provided by a second generation fully threaded headless compression screw compared to a standard headed, partially threaded cancellous screw in a cadaveric ankle arthrodesis model. Twenty fresh frozen human cadaver specimens were subjected to simulated ankle arthrodesis with either three standard cancellous-bone screws (InFix 7.3mm) or with three headless compression screws (Acumed Acutrak 2 7.5mm). The specimens were subjected to cyclic loading and unloading at a rate of 1Hz, compression of 525 Newtons (N) and distraction of 20N for a total of 500 cycles using an electromechanical load frame (Instron). The amount of maximum distraction was recorded as well as the amount of motion that occurred through 1, 10, 50, 100, and 500 cycles. No significant difference (p=0.412) was seen in the amount of distraction that occurred across the fusion site for either screw. The average maximum distraction after 500 cycles was 201.9μm for the Acutrak 2 screw and 235.4μm for the InFix screw. No difference was seen throughout each cycle over time for the Acutrak 2 screw (p-value=0.988) or the InFix screw (p-value=0.991). Both the traditional InFix type screw and the second generation Acumed Acutrak headless compression screws provide adequate fixation during ankle arthrodesis under submaximal loads. There is no demonstrable difference between traditional cannulated partially threaded screws and headless compression screws studied in this model. Copyright © 2015 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

A biphasic approach for the study of lift generation in soft porous media

NASA Astrophysics Data System (ADS)

Wu, Qianhong; Santhanam, Sridhar; Nathan, Rungun; Wang, Qiuyun

2017-04-01

Lift generation in highly compressible porous media under rapid compression continues to be an important topic in porous media flow. Although significant progress has been made, how to model different lifting forces during the compression process remains unclear. This is mainly because the input parameters of the existing theoretical studies, including the Darcy permeability of the porous media and the viscous damping coefficient of its solid phase, were manually adjusted so as to match the experimental data. In the current paper, we report a biphasic approach to experimentally and theoretically treat this limitation. Synthetic fibrous porous materials, whose permeability were precisely measured, were subsequently exposed to sudden impacts using a porous-walled cylinder-piston apparatus. The obtained time-dependent compression of the porous media, along with the permeability data, was applied in two different theoretical models to predict the pore pressure generation, a plug flow model and a consolidation model [Q. Wu et al., J. Fluid Mech. 542, 281 (2005a)]. Comparison between the theory and the experiments on the pore pressure distribution proved the validity of the consolidation model. Furthermore, a viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic generalized Maxwell mechanical module, was developed to characterize the solid phase lifting force. The model matched the experimental data very well. The paper presented herein, as one of the series studies on this topic, provides an important biphasic approach to characterize different forces that contribute to the lift generation in a soft porous medium under rapid compression.

Molecular dynamics simulation of the plastic behavior anisotropy of shock-compressed monocrystal nickel

NASA Astrophysics Data System (ADS)

Chen, Ya-Zhou; Zhou, Liu-Cheng; He, Wei-Feng; Sun, Yu; Li, Ying-Hong; Jiao, Yang; Luo, Si-Hai

2017-01-01

Molecular dynamics simulations were used to study the plastic behavior of monocrystalline nickel under shock compression along the [100] and [110] orientations. The shock Hugoniot relation, local stress curve, and process of microstructure development were determined. Results showed the apparent anisotropic behavior of monocrystalline nickel under shock compression. The separation of elastic and plastic waves was also obvious. Plastic deformation was more severely altered along the [110] direction than the [100] direction. The main microstructure phase transformed from face-centered cubic to body-centered cubic and generated a large-scale and low-density stacking fault along the family of { 111 } crystal planes under shock compression along the [100] direction. By contrast, the main mechanism of plastic deformation in the [110] direction was the nucleation of the hexagonal, close-packed phase, which generated a high density of stacking faults along the [110] and [1̅10] directions.

Handling the data management needs of high-throughput sequencing data: SpeedGene, a compression algorithm for the efficient storage of genetic data

PubMed Central

2012-01-01

Background As Next-Generation Sequencing data becomes available, existing hardware environments do not provide sufficient storage space and computational power to store and process the data due to their enormous size. This is and will be a frequent problem that is encountered everyday by researchers who are working on genetic data. There are some options available for compressing and storing such data, such as general-purpose compression software, PBAT/PLINK binary format, etc. However, these currently available methods either do not offer sufficient compression rates, or require a great amount of CPU time for decompression and loading every time the data is accessed. Results Here, we propose a novel and simple algorithm for storing such sequencing data. We show that, the compression factor of the algorithm ranges from 16 to several hundreds, which potentially allows SNP data of hundreds of Gigabytes to be stored in hundreds of Megabytes. We provide a C++ implementation of the algorithm, which supports direct loading and parallel loading of the compressed format without requiring extra time for decompression. By applying the algorithm to simulated and real datasets, we show that the algorithm gives greater compression rate than the commonly used compression methods, and the data-loading process takes less time. Also, The C++ library provides direct-data-retrieving functions, which allows the compressed information to be easily accessed by other C++ programs. Conclusions The SpeedGene algorithm enables the storage and the analysis of next generation sequencing data in current hardware environment, making system upgrades unnecessary. PMID:22591016

High-performance compression of astronomical images

NASA Technical Reports Server (NTRS)

White, Richard L.

1993-01-01

Astronomical images have some rather unusual characteristics that make many existing image compression techniques either ineffective or inapplicable. A typical image consists of a nearly flat background sprinkled with point sources and occasional extended sources. The images are often noisy, so that lossless compression does not work very well; furthermore, the images are usually subjected to stringent quantitative analysis, so any lossy compression method must be proven not to discard useful information, but must instead discard only the noise. Finally, the images can be extremely large. For example, the Space Telescope Science Institute has digitized photographic plates covering the entire sky, generating 1500 images each having 14000 x 14000 16-bit pixels. Several astronomical groups are now constructing cameras with mosaics of large CCD's (each 2048 x 2048 or larger); these instruments will be used in projects that generate data at a rate exceeding 100 MBytes every 5 minutes for many years. An effective technique for image compression may be based on the H-transform (Fritze et al. 1977). The method that we have developed can be used for either lossless or lossy compression. The digitized sky survey images can be compressed by at least a factor of 10 with no noticeable losses in the astrometric and photometric properties of the compressed images. The method has been designed to be computationally efficient: compression or decompression of a 512 x 512 image requires only 4 seconds on a Sun SPARCstation 1. The algorithm uses only integer arithmetic, so it is completely reversible in its lossless mode, and it could easily be implemented in hardware for space applications.

A Fiber-Optic System Generating Pulses of High Spectral Density

NASA Astrophysics Data System (ADS)

Abramov, A. S.; Zolotovskii, I. O.; Korobko, D. A.; Fotiadi, A. A.

2018-03-01

A cascade fiber-optic system that generates pulses of high spectral density by using the effect of nonlinear spectral compression is proposed. It is demonstrated that the shape of the pulse envelope substantially influences the degree of compression of its spectrum. In so doing, maximum compression is achieved for parabolic pulses. The cascade system includes an optical fiber exhibiting normal dispersion that decreases along the fiber length, thereby ensuring that the pulse envelope evolves toward a parabolic shape, along with diffraction gratings and a fiber spectral compressor. Based on computer simulation, we determined parameters of cascade elements leading to maximum spectral density of radiation originating from a subpicosecond laser pulse of medium energy.

SCALCE: boosting sequence compression algorithms using locally consistent encoding.

PubMed

Hach, Faraz; Numanagic, Ibrahim; Alkan, Can; Sahinalp, S Cenk

2012-12-01

The high throughput sequencing (HTS) platforms generate unprecedented amounts of data that introduce challenges for the computational infrastructure. Data management, storage and analysis have become major logistical obstacles for those adopting the new platforms. The requirement for large investment for this purpose almost signalled the end of the Sequence Read Archive hosted at the National Center for Biotechnology Information (NCBI), which holds most of the sequence data generated world wide. Currently, most HTS data are compressed through general purpose algorithms such as gzip. These algorithms are not designed for compressing data generated by the HTS platforms; for example, they do not take advantage of the specific nature of genomic sequence data, that is, limited alphabet size and high similarity among reads. Fast and efficient compression algorithms designed specifically for HTS data should be able to address some of the issues in data management, storage and communication. Such algorithms would also help with analysis provided they offer additional capabilities such as random access to any read and indexing for efficient sequence similarity search. Here we present SCALCE, a 'boosting' scheme based on Locally Consistent Parsing technique, which reorganizes the reads in a way that results in a higher compression speed and compression rate, independent of the compression algorithm in use and without using a reference genome. Our tests indicate that SCALCE can improve the compression rate achieved through gzip by a factor of 4.19-when the goal is to compress the reads alone. In fact, on SCALCE reordered reads, gzip running time can improve by a factor of 15.06 on a standard PC with a single core and 6 GB memory. Interestingly even the running time of SCALCE + gzip improves that of gzip alone by a factor of 2.09. When compared with the recently published BEETL, which aims to sort the (inverted) reads in lexicographic order for improving bzip2, SCALCE + gzip provides up to 2.01 times better compression while improving the running time by a factor of 5.17. SCALCE also provides the option to compress the quality scores as well as the read names, in addition to the reads themselves. This is achieved by compressing the quality scores through order-3 Arithmetic Coding (AC) and the read names through gzip through the reordering SCALCE provides on the reads. This way, in comparison with gzip compression of the unordered FASTQ files (including reads, read names and quality scores), SCALCE (together with gzip and arithmetic encoding) can provide up to 3.34 improvement in the compression rate and 1.26 improvement in running time. Our algorithm, SCALCE (Sequence Compression Algorithm using Locally Consistent Encoding), is implemented in C++ with both gzip and bzip2 compression options. It also supports multithreading when gzip option is selected, and the pigz binary is available. It is available at http://scalce.sourceforge.net. fhach@cs.sfu.ca or cenk@cs.sfu.ca Supplementary data are available at Bioinformatics online.

Fluid driven torsional dipole seismic source

DOEpatents

Hardee, Harry C.

1991-01-01

A compressible fluid powered oscillating downhole seismic source device capable of periodically generating uncontaminated horizontally-propagated, shear waves is provided. A compressible fluid generated oscillation is created within the device which imparts an oscillation to a housing when the device is installed in a housing such as the cylinder off an existing downhole tool, thereby a torsional seismic source is established. Horizontal waves are transferred to the surrounding bore hole medium through downhole clamping.

[Medical image compression: a review].

PubMed

Noreña, Tatiana; Romero, Eduardo

2013-01-01

Modern medicine is an increasingly complex activity , based on the evidence ; it consists of information from multiple sources : medical record text , sound recordings , images and videos generated by a large number of devices . Medical imaging is one of the most important sources of information since they offer comprehensive support of medical procedures for diagnosis and follow-up . However , the amount of information generated by image capturing gadgets quickly exceeds storage availability in radiology services , generating additional costs in devices with greater storage capacity . Besides , the current trend of developing applications in cloud computing has limitations, even though virtual storage is available from anywhere, connections are made through internet . In these scenarios the optimal use of information necessarily requires powerful compression algorithms adapted to medical activity needs . In this paper we present a review of compression techniques used for image storage , and a critical analysis of them from the point of view of their use in clinical settings.

Combined compressed air storage-low BTU coal gasification power plant

DOEpatents

Kartsounes, George T.; Sather, Norman F.

1979-01-01

An electrical generating power plant includes a Compressed Air Energy Storage System (CAES) fueled with low BTU coal gas generated in a continuously operating high pressure coal gasifier system. This system is used in coordination with a continuously operating main power generating plant to store excess power generated during off-peak hours from the power generating plant, and to return the stored energy as peak power to the power generating plant when needed. The excess coal gas which is produced by the coal gasifier during off-peak hours is stored in a coal gas reservoir. During peak hours the stored coal gas is combined with the output of the coal gasifier to fuel the gas turbines and ultimately supply electrical power to the base power plant.

Pulse compression in a synchronously pumped optical parametric oscillator from group-velocity mismatch.

PubMed

Khaydarov, J D; Andrews, J H; Singer, K D

1994-06-01

We report on experimental intracavity compression of generated pulses (down to one quarter of the pumppulse duration) in a widely tunable synchronously pumped picosecond optical parametric oscillator. This pulse compression takes place when the optical parametric oscillator is well above threshold and is due to the pronounced group-velocity mismatch of the pump and oscillating waves in the nonlinear crystal.

The role of Shabansky orbits in the generation of compression-related EMIC waves

NASA Astrophysics Data System (ADS)

McCollough, J. P.; Elkington, S. R.; Baker, D.

2009-12-01

Electromagnetic ion-cyclotron (EMIC) waves arise from temperature anisotropies in trapped warm plasma populations. In particular, EMIC waves at high L values near local noon are often found to be related to magnetospheric compression events. There are several possible mechanisms that can generate these temperature anisotropies: energizing processes, including adiabatic compression and shock-induced and radial transport; and non-energizing processes, such as drift shell splitting and the effects of off-equatorial minima on particle populations. In this work we investigate the role of off-equatorial minima in the generation of temperature anisotropies both at the magnetic equator and at higher latitudes. There are two kinds of behavior particles undergo in response: particles with high equatorial pitch angles (EPAs) are forced to execute so-called Shabanksy orbits and mirror at high latitudes without passing through the equator, and those with lower EPAs will pass through the equator with higher EPAs than before; as a result, perpendicular energies increase at the cost of parallel energies. By using a 3D particle tracing code in a tunable analytic compressed-dipole field, we parameterize the effects of Shabansky orbits on the anisotropy of the warm plasma. These results as well as evidence from simulations of a real event in which EMIC waves were observed (the compression event of 29 June 2007) are presented.

Lossless Compression of Classification-Map Data

NASA Technical Reports Server (NTRS)

Hua, Xie; Klimesh, Matthew

2009-01-01

A lossless image-data-compression algorithm intended specifically for application to classification-map data is based on prediction, context modeling, and entropy coding. The algorithm was formulated, in consideration of the differences between classification maps and ordinary images of natural scenes, so as to be capable of compressing classification- map data more effectively than do general-purpose image-data-compression algorithms. Classification maps are typically generated from remote-sensing images acquired by instruments aboard aircraft (see figure) and spacecraft. A classification map is a synthetic image that summarizes information derived from one or more original remote-sensing image(s) of a scene. The value assigned to each pixel in such a map is the index of a class that represents some type of content deduced from the original image data for example, a type of vegetation, a mineral, or a body of water at the corresponding location in the scene. When classification maps are generated onboard the aircraft or spacecraft, it is desirable to compress the classification-map data in order to reduce the volume of data that must be transmitted to a ground station.

Friction of Compression-ignition Engines

NASA Technical Reports Server (NTRS)

Moore, Charles S; Collins, John H , Jr

1936-01-01

The cost in mean effective pressure of generating air flow in the combustion chambers of single-cylinder compression-ignition engines was determined for the prechamber and the displaced-piston types of combustion chamber. For each type a wide range of air-flow quantities, speeds, and boost pressures was investigated. Supplementary tests were made to determine the effect of lubricating-oil temperature, cooling-water temperature, and compression ratio on the friction mean effective pressure of the single-cylinder test engine. Friction curves are included for two 9-cylinder, radial, compression-ignition aircraft engines. The results indicate that generating the optimum forced air flow increased the motoring losses approximately 5 pounds per square inch mean effective pressure regardless of chamber type or engine speed. With a given type of chamber, the rate of increase in friction mean effective pressure with engine speed is independent of the air-flow speed. The effect of boost pressure on the friction cannot be predicted because the friction was decreased, unchanged, or increased depending on the combustion-chamber type and design details. High compression ratio accounts for approximately 5 pounds per square inch mean effective pressure of the friction of these single-cylinder compression-ignition engines. The single-cylinder test engines used in this investigation had a much higher friction mean effective pressure than conventional aircraft engines or than the 9-cylinder, radial, compression-ignition engines tested so that performance should be compared on an indicated basis.

Squish: Near-Optimal Compression for Archival of Relational Datasets

PubMed Central

Gao, Yihan; Parameswaran, Aditya

2017-01-01

Relational datasets are being generated at an alarmingly rapid rate across organizations and industries. Compressing these datasets could significantly reduce storage and archival costs. Traditional compression algorithms, e.g., gzip, are suboptimal for compressing relational datasets since they ignore the table structure and relationships between attributes. We study compression algorithms that leverage the relational structure to compress datasets to a much greater extent. We develop Squish, a system that uses a combination of Bayesian Networks and Arithmetic Coding to capture multiple kinds of dependencies among attributes and achieve near-entropy compression rate. Squish also supports user-defined attributes: users can instantiate new data types by simply implementing five functions for a new class interface. We prove the asymptotic optimality of our compression algorithm and conduct experiments to show the effectiveness of our system: Squish achieves a reduction of over 50% in storage size relative to systems developed in prior work on a variety of real datasets. PMID:28180028

Parallel compression of data chunks of a shared data object using a log-structured file system

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

Bent, John M.; Faibish, Sorin; Grider, Gary

2016-10-25

Techniques are provided for parallel compression of data chunks being written to a shared object. A client executing on a compute node or a burst buffer node in a parallel computing system stores a data chunk generated by the parallel computing system to a shared data object on a storage node by compressing the data chunk; and providing the data compressed data chunk to the storage node that stores the shared object. The client and storage node may employ Log-Structured File techniques. The compressed data chunk can be de-compressed by the client when the data chunk is read. A storagemore » node stores a data chunk as part of a shared object by receiving a compressed version of the data chunk from a compute node; and storing the compressed version of the data chunk to the shared data object on the storage node.« less

The behavior of compression and degradation for municipal solid waste and combined settlement calculation method.

PubMed

Shi, Jianyong; Qian, Xuede; Liu, Xiaodong; Sun, Long; Liao, Zhiqiang

2016-09-01

The total compression of municipal solid waste (MSW) consists of primary, secondary, and decomposition compressions. It is usually difficult to distinguish between the three parts of compressions. In this study, the odeometer test was used to distinguish between the primary and secondary compressions to determine the primary and secondary compression coefficient. In addition, the ending time of the primary compressions were proposed based on municipal solid waste compression tests in a degradation-inhibited condition by adding vinegar. The amount of the secondary compression occurring in the primary compression stage has a relatively high percentage to either the total compression or the total secondary compression. The relationship between the degradation ratio and time was obtained from the tests independently. Furthermore, a combined compression calculation method of municipal solid waste for all three parts of compressions including considering organics degradation is proposed based on a one-dimensional compression method. The relationship between the methane generation potential L0 of LandGEM model and degradation compression index was also discussed in the paper. A special column compression apparatus system, which can be used to simulate the whole compression process of municipal solid waste in China, was designed. According to the results obtained from 197-day column compression test, the new combined calculation method for municipal solid waste compression was analyzed. The degradation compression is the main part of the compression of MSW in the medium test period. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improved waste water vapor compression distillation technology. [for Spacelab

NASA Technical Reports Server (NTRS)

Johnson, K. L.; Nuccio, P. P.; Reveley, W. F.

1977-01-01

The vapor compression distillation process is a method of recovering potable water from crewman urine in a manned spacecraft or space station. A description is presented of the research and development approach to the solution of the various problems encountered with previous vapor compression distillation units. The design solutions considered are incorporated in the preliminary design of a vapor compression distillation subsystem. The new design concepts are available for integration in the next generation of support systems and, particularly, the regenerative life support evaluation intended for project Spacelab.

Cardiac pacemaker dysfunction in children after thoracic drainage catheter manipulation.

PubMed

Lobdell, K W; Walters, H L; Hudson, C; Hakimi, M

1997-05-01

Two children underwent placement of permanent, epicardial-lead, dual-chamber, unipolar pacemaker systems for complete heart block. Postoperatively, both patients demonstrated subcutaneous emphysema-in the area of their pulse generators-temporally related to thoracic catheter manipulation. Acutely, each situation was managed with manual compression of the pulse generator, ascertaining appropriate pacemaker sensing and pacing. Maintenance of compression with pressure dressings, vigilant observation/monitoring, and education of the care givers resulted in satisfactory pacemaker function without invasive intervention.

Pre-loading of components during laser peenforming

DOEpatents

Hackel, Lloyd A [Livermore, CA; Halpin, John M [Tracy, CA; Harris, Fritz B [Rocklin, CA

2003-12-30

A method and apparatus are provided for forming shapes and contours in metal sections by prestressing a workpiece and generating laser induced compressive stress on the surface of the metal workpiece. The step of prestressing the workpiece is carried out with a jig. The laser process can generate deep compressive stresses to shape even thick components without inducing unwanted tensile stress at the metal surface. The precision of the laser-induced stress enables exact prediction and subsequent contouring of parts.

Image compression system and method having optimized quantization tables

NASA Technical Reports Server (NTRS)

Ratnakar, Viresh (Inventor); Livny, Miron (Inventor)

1998-01-01

A digital image compression preprocessor for use in a discrete cosine transform-based digital image compression device is provided. The preprocessor includes a gathering mechanism for determining discrete cosine transform statistics from input digital image data. A computing mechanism is operatively coupled to the gathering mechanism to calculate a image distortion array and a rate of image compression array based upon the discrete cosine transform statistics for each possible quantization value. A dynamic programming mechanism is operatively coupled to the computing mechanism to optimize the rate of image compression array against the image distortion array such that a rate-distortion-optimal quantization table is derived. In addition, a discrete cosine transform-based digital image compression device and a discrete cosine transform-based digital image compression and decompression system are provided. Also, a method for generating a rate-distortion-optimal quantization table, using discrete cosine transform-based digital image compression, and operating a discrete cosine transform-based digital image compression and decompression system are provided.

Compact Encoding of Robot-Generated 3D Maps for Efficient Wireless Transmission

DTIC Science & Technology

2003-01-01

Lempel - Ziv -Welch (LZW) and Ziv - Lempel (LZ77) respectively. Image based compression can also be based on dic- tionaries... compression of the data , without actually displaying a 3D model, printing statistical results for comparison of the different algorithms . 1http... compression algorithms , and wavelet algorithms tuned to the specific nature of the raw laser data . For most such applications, the usage of lossless

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir (Appendix)

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir

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

Medeiros, Michael; Booth, Robert; Fairchild, James

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Compressed Air/Vacuum Transportation Techniques

NASA Astrophysics Data System (ADS)

Guha, Shyamal

2011-03-01

General theory of compressed air/vacuum transportation will be presented. In this transportation, a vehicle (such as an automobile or a rail car) is powered either by compressed air or by air at near vacuum pressure. Four version of such transportation is feasible. In all versions, a ``c-shaped'' plastic or ceramic pipe lies buried a few inches under the ground surface. This pipe carries compressed air or air at near vacuum pressure. In type I transportation, a vehicle draws compressed air (or vacuum) from this buried pipe. Using turbine or reciprocating air cylinder, mechanical power is generated from compressed air (or from vacuum). This mechanical power transferred to the wheels of an automobile (or a rail car) drives the vehicle. In type II-IV transportation techniques, a horizontal force is generated inside the plastic (or ceramic) pipe. A set of vertical and horizontal steel bars is used to transmit this force to the automobile on the road (or to a rail car on rail track). The proposed transportation system has following merits: virtually accident free; highly energy efficient; pollution free and it will not contribute to carbon dioxide emission. Some developmental work on this transportation will be needed before it can be used by the traveling public. The entire transportation system could be computer controlled.

Quasi-remote Pulse Compression and Generation of Radiation and Particle Beams

NASA Astrophysics Data System (ADS)

Hubbard, Richard F.; Ting, Antonio; Penano, Joseph R.; Hafizi, Bahman; Gordon, Daniel F.; Sprangle, Phillip; Zigler, Arie

2013-10-01

Using chirped pulse amplification (CPA), laser pulses are routinely compressed to pulse lengths below 50 femtoseconds and focused to spot sizes of a few microns. These intense pulses may be focused onto a solid, gas, or plasma converter to produce penetrating electromagnetic radiation (e.g., x-rays, terahertz) or energetic particles. However, nonlinear effects and plasma generation place severe restrictions on the intensity of the pulse that can be propagated through the air to a distant target or object. This paper describes a quasi-remote laser pulse compression architecture in which the pulse compression apparatus, focusing system, and radiation or particle beam converter are placed at a substantial distance from the rest of the CPA system. By propagating a radially-expanded, chirped/stretched pulse through the air at a sufficiently low intensity, the stretched pulse can be compressed and focused onto the converter while keeping the largest and most expensive components of the CPA system far from the object to be irradiated. Analytical and simulation models are used to determine how axial compression and focused spot size degrade as the standoff distance to the compressor/focusing/converter assembly is increased. The implications of these results for proof-of-concept experiments and various potential applications will be discussed. Supported by the NRL Base Program

Corpuls CPR Generates Higher Mean Arterial Pressure Than LUCAS II in a Pig Model of Cardiac Arrest.

PubMed

Eichhorn, S; Mendoza, A; Prinzing, A; Stroh, A; Xinghai, L; Polski, M; Heller, M; Lahm, H; Wolf, E; Lange, R; Krane, M

2017-01-01

According to the European Resuscitation Council guidelines, the use of mechanical chest compression devices is a reasonable alternative in situations where manual chest compression is impractical or compromises provider safety. The aim of this study is to compare the performance of a recently developed chest compression device (Corpuls CPR) with an established system (LUCAS II) in a pig model. Methods . Pigs ( n = 5/group) in provoked ventricular fibrillation were left untreated for 5 minutes, after which 15 min of cardiopulmonary resuscitation was performed with chest compressions. After 15 min, defibrillation was performed every 2 min if necessary, and up to 3 doses of adrenaline were given. If there was no return of spontaneous circulation after 25 min, the experiment was terminated. Coronary perfusion pressure, carotid blood flow, end-expiratory CO 2 , regional oxygen saturation by near infrared spectroscopy, blood gas, and local organ perfusion with fluorescent labelled microspheres were measured at baseline and during resuscitation. Results . Animals treated with Corpuls CPR had significantly higher mean arterial pressures during resuscitation, along with a detectable trend of greater carotid blood flow and organ perfusion. Conclusion . Chest compressions with the Corpuls CPR device generated significantly higher mean arterial pressures than compressions performed with the LUCAS II device.

Corpuls CPR Generates Higher Mean Arterial Pressure Than LUCAS II in a Pig Model of Cardiac Arrest

PubMed Central

Mendoza, A.; Prinzing, A.; Stroh, A.; Xinghai, L.; Polski, M.; Heller, M.; Lahm, H.; Wolf, E.; Lange, R.; Krane, M.

2017-01-01

According to the European Resuscitation Council guidelines, the use of mechanical chest compression devices is a reasonable alternative in situations where manual chest compression is impractical or compromises provider safety. The aim of this study is to compare the performance of a recently developed chest compression device (Corpuls CPR) with an established system (LUCAS II) in a pig model. Methods. Pigs (n = 5/group) in provoked ventricular fibrillation were left untreated for 5 minutes, after which 15 min of cardiopulmonary resuscitation was performed with chest compressions. After 15 min, defibrillation was performed every 2 min if necessary, and up to 3 doses of adrenaline were given. If there was no return of spontaneous circulation after 25 min, the experiment was terminated. Coronary perfusion pressure, carotid blood flow, end-expiratory CO2, regional oxygen saturation by near infrared spectroscopy, blood gas, and local organ perfusion with fluorescent labelled microspheres were measured at baseline and during resuscitation. Results. Animals treated with Corpuls CPR had significantly higher mean arterial pressures during resuscitation, along with a detectable trend of greater carotid blood flow and organ perfusion. Conclusion. Chest compressions with the Corpuls CPR device generated significantly higher mean arterial pressures than compressions performed with the LUCAS II device. PMID:29392137

iDoComp: a compression scheme for assembled genomes

PubMed Central

Ochoa, Idoia; Hernaez, Mikel; Weissman, Tsachy

2015-01-01

Motivation: With the release of the latest next-generation sequencing (NGS) machine, the HiSeq X by Illumina, the cost of sequencing a Human has dropped to a mere $4000. Thus we are approaching a milestone in the sequencing history, known as the $1000 genome era, where the sequencing of individuals is affordable, opening the doors to effective personalized medicine. Massive generation of genomic data, including assembled genomes, is expected in the following years. There is crucial need for compression of genomes guaranteed of performing well simultaneously on different species, from simple bacteria to humans, which will ease their transmission, dissemination and analysis. Further, most of the new genomes to be compressed will correspond to individuals of a species from which a reference already exists on the database. Thus, it is natural to propose compression schemes that assume and exploit the availability of such references. Results: We propose iDoComp, a compressor of assembled genomes presented in FASTA format that compresses an individual genome using a reference genome for both the compression and the decompression. In terms of compression efficiency, iDoComp outperforms previously proposed algorithms in most of the studied cases, with comparable or better running time. For example, we observe compression gains of up to 60% in several cases, including H.sapiens data, when comparing with the best compression performance among the previously proposed algorithms. Availability: iDoComp is written in C and can be downloaded from: http://www.stanford.edu/~iochoa/iDoComp.html (We also provide a full explanation on how to run the program and an example with all the necessary files to run it.). Contact: iochoa@stanford.edu Supplementary information: Supplementary Data are available at Bioinformatics online. PMID:25344501

Energy compression of nanosecond high-voltage pulses based on two-stage hybrid scheme

NASA Astrophysics Data System (ADS)

Ulmaskulov, M. R.; Mesyats, G. A.; Sadykova, A. G.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.; Yalandin, M. I.

2017-04-01

Test results of high-voltage subnanosecond pulse generator with a hybrid, two-stage energy compression scheme are presented. After the first compression section with a gas discharger, a ferrite-filled gyromagnetic nonlinear transmitting line is used. The offered technical solution makes it possible to increase the voltage pulse amplitude from -185 kV to -325 kV, with a 2-ns pulse rise time minimized down to ˜180 ps. For the small output voltage amplitude of -240 kV, the shortest pulse front of ˜85 ps was obtained. The generator with maximum amplitude was utilized to form an ultra-short flow of runaway electrons in air-filled discharge gap with particles' energy approaching to 700 keV.

Triggering Factor of Strong Earthquakes and Its Prediction Verification

NASA Astrophysics Data System (ADS)

Ren, Z. Q.; Ren, S. H.

After 30 yearsS research, we have found that great earthquakes are triggered by tide- generation force of the moon. ItSs not the tide-generation force in classical view- points, but is a non-classical viewpoint tide-generation force. We call it as TGFR (Tide-Generation ForcesS Resonance). TGFR strongly depends on the tide-generation force at time of the strange astronomical points (SAP). The SAP mostly are when the moon and another celestial body are arranged with the earth along a straight line (with the same apparent right ascension or 180o difference), the other SAP are the turning points of the moonSs relatively motion to the earth. Moreover, TGFR have four different types effective areas. Our study indicates that a majority of earthquakes are triggering by the rare superimposition of TGFRsS effective areas. In China the great earthquakes in the plain area of Hebei Province, Taiwan, Yunnan Province and Sichuan province are trigger by the decompression TGFR; Other earthquakes are trig- gered by compression TGFR which are in Gansu Province, Ningxia Provinces and northwest direction of Beijing. The great earthquakes in Japan, California, southeast of Europe also are triggered by compression of the TGFR. and in the other part of the world like in Philippines, Central America countries, and West Asia, great earthquakes are triggered by decompression TGFR. We have carried out examinational immediate prediction cooperate TGFR method with other earthquake impending signals such as suggested by Professor Li Junzhi. The successful ratio is about 40%(from our fore- cast reports to the China Seismological Administration). Thus we could say the great earthquake can be predicted (include immediate earthquake prediction). Key words: imminent prediction; triggering factor; TGFR (Tide-Generation ForcesS Resonance); TGFR compression; TGFR compression zone; TGFR decompression; TGFR decom- pression zone

Brainstem removal using compressed air for subsequent bovine spongiform encephalopathy testing

PubMed Central

2005-01-01

Abstract The use of compressed air to expel the obex through a hole in the skull generated using a captured bolt stunner. The obex is the part of the brain that is tested for bovine spongiform encephalopathy. PMID:16018564

Operational procedure for computer program for design point characteristics of a compressed-air generator with through-flow combustor for V/STOL applications

NASA Technical Reports Server (NTRS)

Krebs, R. P.

1971-01-01

The computer program described in this report calculates the design-point characteristics of a compressed-air generator for use in V/STOL applications such as systems with a tip-turbine-driven lift fan. The program computes the dimensions and mass, as well as the thermodynamic performance of a model air generator configuration which involves a straight through-flow combustor. Physical and thermodynamic characteristics of the air generator components are also given. The program was written in FORTRAN IV language. Provision has been made so that the program will accept input values in either SI units or U.S. customary units. Each air generator design-point calculation requires about 1.5 seconds of 7094 computer time for execution.

Novel Data Reduction Based on Statistical Similarity

DOE PAGES

Lee, Dongeun; Sim, Alex; Choi, Jaesik; ...

2016-07-18

Applications such as scientific simulations and power grid monitoring are generating so much data quickly that compression is essential to reduce storage requirement or transmission capacity. To achieve better compression, one is often willing to discard some repeated information. These lossy compression methods are primarily designed to minimize the Euclidean distance between the original data and the compressed data. But this measure of distance severely limits either reconstruction quality or compression performance. In this paper, we propose a new class of compression method by redefining the distance measure with a statistical concept known as exchangeability. This approach reduces the storagemore » requirement and captures essential features, while reducing the storage requirement. In this paper, we report our design and implementation of such a compression method named IDEALEM. To demonstrate its effectiveness, we apply it on a set of power grid monitoring data, and show that it can reduce the volume of data much more than the best known compression method while maintaining the quality of the compressed data. Finally, in these tests, IDEALEM captures extraordinary events in the data, while its compression ratios can far exceed 100.« less

SCALCE: boosting sequence compression algorithms using locally consistent encoding

PubMed Central

Hach, Faraz; Numanagić, Ibrahim; Sahinalp, S Cenk

2012-01-01

Motivation: The high throughput sequencing (HTS) platforms generate unprecedented amounts of data that introduce challenges for the computational infrastructure. Data management, storage and analysis have become major logistical obstacles for those adopting the new platforms. The requirement for large investment for this purpose almost signalled the end of the Sequence Read Archive hosted at the National Center for Biotechnology Information (NCBI), which holds most of the sequence data generated world wide. Currently, most HTS data are compressed through general purpose algorithms such as gzip. These algorithms are not designed for compressing data generated by the HTS platforms; for example, they do not take advantage of the specific nature of genomic sequence data, that is, limited alphabet size and high similarity among reads. Fast and efficient compression algorithms designed specifically for HTS data should be able to address some of the issues in data management, storage and communication. Such algorithms would also help with analysis provided they offer additional capabilities such as random access to any read and indexing for efficient sequence similarity search. Here we present SCALCE, a ‘boosting’ scheme based on Locally Consistent Parsing technique, which reorganizes the reads in a way that results in a higher compression speed and compression rate, independent of the compression algorithm in use and without using a reference genome. Results: Our tests indicate that SCALCE can improve the compression rate achieved through gzip by a factor of 4.19—when the goal is to compress the reads alone. In fact, on SCALCE reordered reads, gzip running time can improve by a factor of 15.06 on a standard PC with a single core and 6 GB memory. Interestingly even the running time of SCALCE + gzip improves that of gzip alone by a factor of 2.09. When compared with the recently published BEETL, which aims to sort the (inverted) reads in lexicographic order for improving bzip2, SCALCE + gzip provides up to 2.01 times better compression while improving the running time by a factor of 5.17. SCALCE also provides the option to compress the quality scores as well as the read names, in addition to the reads themselves. This is achieved by compressing the quality scores through order-3 Arithmetic Coding (AC) and the read names through gzip through the reordering SCALCE provides on the reads. This way, in comparison with gzip compression of the unordered FASTQ files (including reads, read names and quality scores), SCALCE (together with gzip and arithmetic encoding) can provide up to 3.34 improvement in the compression rate and 1.26 improvement in running time. Availability: Our algorithm, SCALCE (Sequence Compression Algorithm using Locally Consistent Encoding), is implemented in C++ with both gzip and bzip2 compression options. It also supports multithreading when gzip option is selected, and the pigz binary is available. It is available at http://scalce.sourceforge.net. Contact: fhach@cs.sfu.ca or cenk@cs.sfu.ca Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23047557

Electroencephalographic compression based on modulated filter banks and wavelet transform.

PubMed

Bazán-Prieto, Carlos; Cárdenas-Barrera, Julián; Blanco-Velasco, Manuel; Cruz-Roldán, Fernando

2011-01-01

Due to the large volume of information generated in an electroencephalographic (EEG) study, compression is needed for storage, processing or transmission for analysis. In this paper we evaluate and compare two lossy compression techniques applied to EEG signals. It compares the performance of compression schemes with decomposition by filter banks or wavelet Packets transformation, seeking the best value for compression, best quality and more efficient real time implementation. Due to specific properties of EEG signals, we propose a quantization stage adapted to the dynamic range of each band, looking for higher quality. The results show that the compressor with filter bank performs better than transform methods. Quantization adapted to the dynamic range significantly enhances the quality.

Turbulence Generation Using Localized Sources of Energy: Direct Numerical Simulations and the Effects of Thermal Non-Equilibrium

NASA Astrophysics Data System (ADS)

Maqui, Agustin Francisco

Turbulence in high-speed flows is an important problem in aerospace applications, yet extremely difficult from a theoretical, computational and experimental perspective. A main reason for the lack of complete understanding is the difficulty of generating turbulence in the lab at a range of speeds which can also include hypersonic effects such as thermal non-equilibrium. This work studies the feasibility of a new approach to generate turbulence based on laser-induced photo-excitation/dissociation of seeded molecules. A large database of incompressible and compressible direct numerical simulations (DNS) has been generated to systematically study the development and evolution of the flow towards realistic turbulence. Governing parameters and the conditions necessary for the establishment of turbulence, as well as the length and time scales associated with such process, are identified. For both the compressible and incompressible experiments a minimum Reynolds number is found to be needed for the flow to evolve towards fully developed turbulence. Additionally, for incompressible cases a minimum time scale is required, while for compressible cases a minimum distance from the grid and limit on the maximum temperature introduced are required. Through an extensive analysis of single and two point statistics, as well as spectral dynamics, the primary mechanisms leading to turbulence are shown. As commonly done in compressible turbulence, dilatational and solenoidal components are separated to understand the effect of acoustics on the development of turbulence. Finally, a large database of forced isotropic turbulence has been generated to study the effect of internal degrees of freedom on the evolution of turbulence.

Generation and Analysis of Subpicosecond Double Electron Bunch at the Brookhaven Accelerator Test Facility

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

Babzien, M.; Kusche, K.; Yakimenko, V.

2011-08-09

Two compressed electron beam bunches from a single 60-MeV bunch have been generated in a reproducible manner during compression in the magnetic chicane - 'dog leg' arrangement at ATF. Measurements indicate they have comparable bunch lengths ({approx}100-200 fs) and are separated in energy by {approx}1.8 MeV with the higher-energy bunch preceding the lower-energy bunch by 0.5-1 ps. Some simulation results for analyzing the double-bunch formation process are also presented.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 7

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 6

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 4

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 9

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 3

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 5

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Simultaneous dual mode combustion engine operating on spark ignition and homogenous charge compression ignition

DOEpatents

Fiveland, Scott B.; Wiggers, Timothy E.

2004-06-22

An engine particularly suited to single speed operation environments, such as stationary power generators. The engine includes a plurality of combustion cylinders operable under homogenous charge compression ignition, and at least one combustion cylinder operable on spark ignition concepts. The cylinder operable on spark ignition concepts can be convertible to operate under homogenous charge compression ignition. The engine is started using the cylinders operable under spark ignition concepts.

Technical Feasibility of Compressed Air Energy Storage (CAES) Utilizing a Porous Rock Reservoir, Appendix — Chapter 8

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

Medeiros, Michael

Pacific Gas & Electric Company (PG&E) conducted a project to explore the viability of underground compressed air energy storage (CAES) technology. CAES uses low-cost, off-peak electricity to compress air into a storage system in an underground space such as a rock formation or salt cavern. When electricity is needed, the air is withdrawn and used to drive a generator for electricity production.

Redistribution of Welding Residual Stresses of Crack Tip Opening Displacement Specimen by Local Compression.

PubMed

Kim, Young-Gon; Song, Kuk-Hyun; Lee, Dong-Hoon; Joo, Sung-Min

2018-03-01

The demand of crack tip opening displacement (CTOD) test which evaluates fracture toughness of a cracked material is very important to ensure the stability of structure under severe service environment. The validity of the CTOD test result is judged using several criterions of the specification standards. One of them is the artificially generated fatigue pre-crack length inside the specimen. For acceptable CTOD test results, fatigue pre-crack must have a reasonable sharp crack front. The propagation of fatigue crack started from the tip of the machined notch, which might have propagated irregularly due to residual stress field. To overcome this problem, test codes suggest local compression method, reversed bending method and stepwise high-R ratio method to reduce the disparity of residual stress distribution inside the specimen. In this paper, the relation between the degree of local compression and distribution of welding residual stress has been analyzed by finite element analyses in order to determine the amount of effective local compression of the test piece. Analysis results show that initial welding residual stress is dramatically varied three-dimensionally while cutting, notch machining and local compressing due to the change of internal restraint force. From the simulation result, the authors find that there is an optimum amount of local compression to modify regularly for generating fatigue pre-crack propagation. In the case of 0.5% compressions of the model width is the most effective for uniforming residual stress distribution.

Vortex Generators in a Two-Dimensional, External-Compression Supersonic Inlet

NASA Technical Reports Server (NTRS)

Baydar, Ezgihan; Lu, Frank K.; Slater, John W.

2016-01-01

Vortex generators within a two-dimensional, external-compression supersonic inlet for Mach 1.6 were investigated to determine their ability to increase total pressure recovery, reduce total pressure distortion, and improve the boundary layer. The vortex generators studied included vanes and ramps. The geometric factors of the vortex generators studied included height, length, spacing, and positions upstream and downstream of the inlet terminal shock. The flow through the inlet was simulated through the computational solution of the steady-state Reynolds-averaged Navier-Stokes equations on multi-block, structured grids. The vortex generators were simulated by either gridding the geometry of the vortex generators or modeling the vortices generated by the vortex generators. The inlet performance was characterized by the inlet total pressure recovery, total pressure distortion, and incompressible shape factor of the boundary-layer at the engine face. The results suggested that downstream vanes reduced the distortion and improved the boundary layer. The height of the vortex generators had the greatest effect of the geometric factors.

Dynamic Material Properties of Orthotropic Polymer and Molybdenum for Use in Next Generation Composite Armor Concept?

DTIC Science & Technology

2011-06-01

1. Shock Compression Experimental Techniques ...............................22 a. Target...3 Figure 2. Composite plate (left) shown by Poh defeating Tantalum projectile while armor grade steel (right) failed...entire target buildup used for a shock compression experiment ..................................................................................23 Figure

Compressing climate model simulations: reducing storage burden while preserving information

NASA Astrophysics Data System (ADS)

Hammerling, Dorit; Baker, Allison; Xu, Haiying; Clyne, John; Li, Samuel

2017-04-01

Climate models, which are run at high spatial and temporal resolutions, generate massive quantities of data. As our computing capabilities continue to increase, storing all of the generated data is becoming a bottleneck, which negatively affects scientific progress. It is thus important to develop methods for representing the full datasets by smaller compressed versions, which still preserve all the critical information and, as an added benefit, allow for faster read and write operations during analysis work. Traditional lossy compression algorithms, as for example used for image files, are not necessarily ideally suited for climate data. While visual appearance is relevant, climate data has additional critical features such as the preservation of extreme values and spatial and temporal gradients. Developing alternative metrics to quantify information loss in a manner that is meaningful to climate scientists is an ongoing process still in its early stages. We will provide an overview of current efforts to develop such metrics to assess existing algorithms and to guide the development of tailored compression algorithms to address this pressing challenge.

Comprehensive numerical methodology for direct numerical simulations of compressible Rayleigh-Taylor instability

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

Reckinger, Scott James; Livescu, Daniel; Vasilyev, Oleg V.

A comprehensive numerical methodology has been developed that handles the challenges introduced by considering the compressive nature of Rayleigh-Taylor instability (RTI) systems, which include sharp interfacial density gradients on strongly stratified background states, acoustic wave generation and removal at computational boundaries, and stratification-dependent vorticity production. The computational framework is used to simulate two-dimensional single-mode RTI to extreme late-times for a wide range of flow compressibility and variable density effects. The results show that flow compressibility acts to reduce the growth of RTI for low Atwood numbers, as predicted from linear stability analysis.

46 CFR 112.50-7 - Compressed air starting.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Diesel and Gas Turbine Engine Driven Generator Sets § 112.50-7 Compressed... emergency power source. If this compressor supplies other auxiliaries, there must be a non-return valve at...

A 3-dimensional mass conserving element for compressible flows

NASA Technical Reports Server (NTRS)

Fix, G.; Suri, M.

1985-01-01

A variety of finite element schemes has been used in the numerical approximation of compressible flows particularly in underwater acoustics. In many instances instabilities have been generated due to the lack of mass conservation. Two- and three-dimensional elements are developed which avoid these problems.

Characterizing inner-shell with spectral phase interferometry for direct electric-field reconstruction

PubMed Central

Mashiko, Hiroki; Yamaguchi, Tomohiko; Oguri, Katsuya; Suda, Akira; Gotoh, Hideki

2014-01-01

In many atomic, molecular and solid systems, Lorentzian and Fano profiles are commonly observed in a broad research fields throughout a variety of spectroscopies. As the profile structure is related to the phase of the time-dependent dipole moment, it plays an important role in the study of quantum properties. Here we determine the dipole phase in the inner-shell transition using spectral phase interferometry for direct electric-field reconstruction (SPIDER) with isolated attosecond pulses (IAPs). In addition, we propose a scheme for pulse generation and compression by manipulating the inner-shell transition. The electromagnetic radiation generated by the transition is temporally compressed to a few femtoseconds in the extreme ultraviolet (XUV) region. The proposed pulse-compression scheme may provide an alternative route to producing attosecond pulses of light. PMID:25510971

Adaptive efficient compression of genomes

PubMed Central

2012-01-01

Modern high-throughput sequencing technologies are able to generate DNA sequences at an ever increasing rate. In parallel to the decreasing experimental time and cost necessary to produce DNA sequences, computational requirements for analysis and storage of the sequences are steeply increasing. Compression is a key technology to deal with this challenge. Recently, referential compression schemes, storing only the differences between a to-be-compressed input and a known reference sequence, gained a lot of interest in this field. However, memory requirements of the current algorithms are high and run times often are slow. In this paper, we propose an adaptive, parallel and highly efficient referential sequence compression method which allows fine-tuning of the trade-off between required memory and compression speed. When using 12 MB of memory, our method is for human genomes on-par with the best previous algorithms in terms of compression ratio (400:1) and compression speed. In contrast, it compresses a complete human genome in just 11 seconds when provided with 9 GB of main memory, which is almost three times faster than the best competitor while using less main memory. PMID:23146997

Image splitting and remapping method for radiological image compression

NASA Astrophysics Data System (ADS)

Lo, Shih-Chung B.; Shen, Ellen L.; Mun, Seong K.

1990-07-01

A new decomposition method using image splitting and gray-level remapping has been proposed for image compression, particularly for images with high contrast resolution. The effects of this method are especially evident in our radiological image compression study. In our experiments, we tested the impact of this decomposition method on image compression by employing it with two coding techniques on a set of clinically used CT images and several laser film digitized chest radiographs. One of the compression techniques used was full-frame bit-allocation in the discrete cosine transform domain, which has been proven to be an effective technique for radiological image compression. The other compression technique used was vector quantization with pruned tree-structured encoding, which through recent research has also been found to produce a low mean-square-error and a high compression ratio. The parameters we used in this study were mean-square-error and the bit rate required for the compressed file. In addition to these parameters, the difference between the original and reconstructed images will be presented so that the specific artifacts generated by both techniques can be discerned by visual perception.

Chaos-Based Simultaneous Compression and Encryption for Hadoop.

PubMed

Usama, Muhammad; Zakaria, Nordin

2017-01-01

Data compression and encryption are key components of commonly deployed platforms such as Hadoop. Numerous data compression and encryption tools are presently available on such platforms and the tools are characteristically applied in sequence, i.e., compression followed by encryption or encryption followed by compression. This paper focuses on the open-source Hadoop framework and proposes a data storage method that efficiently couples data compression with encryption. A simultaneous compression and encryption scheme is introduced that addresses an important implementation issue of source coding based on Tent Map and Piece-wise Linear Chaotic Map (PWLM), which is the infinite precision of real numbers that result from their long products. The approach proposed here solves the implementation issue by removing fractional components that are generated by the long products of real numbers. Moreover, it incorporates a stealth key that performs a cyclic shift in PWLM without compromising compression capabilities. In addition, the proposed approach implements a masking pseudorandom keystream that enhances encryption quality. The proposed algorithm demonstrated a congruent fit within the Hadoop framework, providing robust encryption security and compression.

A New Compression Method for FITS Tables

NASA Technical Reports Server (NTRS)

Pence, William; Seaman, Rob; White, Richard L.

2010-01-01

As the size and number of FITS binary tables generated by astronomical observatories increases, so does the need for a more efficient compression method to reduce the amount disk space and network bandwidth required to archive and down1oad the data tables. We have developed a new compression method for FITS binary tables that is modeled after the FITS tiled-image compression compression convention that has been in use for the past decade. Tests of this new method on a sample of FITS binary tables from a variety of current missions show that on average this new compression technique saves about 50% more disk space than when simply compressing the whole FITS file with gzip. Other advantages of this method are (1) the compressed FITS table is itself a valid FITS table, (2) the FITS headers remain uncompressed, thus allowing rapid read and write access to the keyword values, and (3) in the common case where the FITS file contains multiple tables, each table is compressed separately and may be accessed without having to uncompress the whole file.

Chaos-Based Simultaneous Compression and Encryption for Hadoop

PubMed Central

Zakaria, Nordin

2017-01-01

Data compression and encryption are key components of commonly deployed platforms such as Hadoop. Numerous data compression and encryption tools are presently available on such platforms and the tools are characteristically applied in sequence, i.e., compression followed by encryption or encryption followed by compression. This paper focuses on the open-source Hadoop framework and proposes a data storage method that efficiently couples data compression with encryption. A simultaneous compression and encryption scheme is introduced that addresses an important implementation issue of source coding based on Tent Map and Piece-wise Linear Chaotic Map (PWLM), which is the infinite precision of real numbers that result from their long products. The approach proposed here solves the implementation issue by removing fractional components that are generated by the long products of real numbers. Moreover, it incorporates a stealth key that performs a cyclic shift in PWLM without compromising compression capabilities. In addition, the proposed approach implements a masking pseudorandom keystream that enhances encryption quality. The proposed algorithm demonstrated a congruent fit within the Hadoop framework, providing robust encryption security and compression. PMID:28072850

Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression

NASA Astrophysics Data System (ADS)

Varshnay, N. K.; Singh, A.; Benerji, N. S.

2017-02-01

Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression suitable for material processing applications are presented here. The laser incorporates in-built compact gas circulation and gas cooling to ensure fresh gas mixture between the electrodes for repetitive operation. A magnetically coupled tangential blower is used for gas circulation inside the laser chamber for repetitive operation. The exciter consists of C-C energy transfer circuit and thyratron is used as a high-voltage main switch with single-stage magnetic pulse compression (MPC) between thyratron and the laser electrodes. Low inductance of the laser head and uniform and intense pre-ionization are the main features of the electric circuit used in the laser. A 250 ns rise time voltage pulse was compressed to 100 ns duration with a single-stage magnetic pulse compressor using Ni-Zn ferrite cores. The laser can generate about 150 mJ at ˜100 Hz rep-rate reliably from a discharge volume of 100 cm 3. 2D spatial laser beam profile generated is presented here. The profile shows that the laser beam is completely filled with flat-top which is suitable for material processing applications. The SEM image of the microhole generated on copper target is presented here.

Fabricating Atom-Sized Gaps by Field-Aided Atom Migration in Nanoscale Junctions

NASA Astrophysics Data System (ADS)

Liu, Ran; Bi, Jun-Jie; Xie, Zhen; Yin, Kaikai; Wang, Dunyou; Zhang, Guang-Ping; Xiang, Dong; Wang, Chuan-Kui; Li, Zong-Liang

2018-05-01

The gap sizes between electrodes generated by typical methods are generally much larger than the dimension of a common molecule when fabricating a single-molecule junction, which dramatically suppresses the yield of single-molecule junctions. Based on the ab initio calculations, we develop a strategy named the field-aided method to accurately fabricate an atomic-sized gap between gold nanoelectrodes. To understand the mechanism of this strategy, configuration evolutions of gold nanojunction in stretching and compressing processes are calculated. The numerical results show that, in the stretching process, the gold atoms bridged between two electrodes are likely to form atomic chains. More significantly, lattice vacant positions can be easily generated in stretching and compressing processes, which make field-aided gap generation possible. In field-aided atom migration (FAAM), the external field can exert driving force, enhance the initial energy of the system, and decrease the barrier in the migration path, which makes the atom migration feasible. Conductance and stretching and compressing forces, as measurable variables in stretching and compressing processes, present very useful signals for determining the time to perform FAAM. Following this desirable strategy, we successfully fabricate gold nanogaps with a dimension of 0.38 ±0.05 nm in the experiment, as our calculation simulates.

Temperature distortion generator for turboshaft engine testing

NASA Technical Reports Server (NTRS)

Klann, G. A.; Barth, R. L.; Biesiadny, T. J.

1984-01-01

The procedures and unique hardware used to conduct an experimental investigation into the response of a small-turboshaft-engine compression system to various hot gas ingestion patterns are presented. The temperature distortion generator described herein uses gaseous hydrogen to create both steady-state and time-variant, or transient, temperature distortion at the engine inlet. The range of transient temperature ramps produced by the distortion generator during the engine tests was from less than 111 deg K/sec (200 deg R/sec) to above 611 deg K/sec (1100 deg R/sec); instantaneous temperatures to 422 deg K (760 deg R) above ambient were generated. The distortion generator was used to document the maximum inlet temperatures and temperature rise rates that the compression system could tolerate before the onset of stall for various circumferential distortions as well as the compressor system response during stall.

Some Practical Universal Noiseless Coding Techniques

NASA Technical Reports Server (NTRS)

Rice, Robert F.

1994-01-01

Report discusses noiseless data-compression-coding algorithms, performance characteristics and practical consideration in implementation of algorithms in coding modules composed of very-large-scale integrated circuits. Report also has value as tutorial document on data-compression-coding concepts. Coding techniques and concepts in question "universal" in sense that, in principle, applicable to streams of data from variety of sources. However, discussion oriented toward compression of high-rate data generated by spaceborne sensors for lower-rate transmission back to earth.

Reference-free compression of high throughput sequencing data with a probabilistic de Bruijn graph.

PubMed

Benoit, Gaëtan; Lemaitre, Claire; Lavenier, Dominique; Drezen, Erwan; Dayris, Thibault; Uricaru, Raluca; Rizk, Guillaume

2015-09-14

Data volumes generated by next-generation sequencing (NGS) technologies is now a major concern for both data storage and transmission. This triggered the need for more efficient methods than general purpose compression tools, such as the widely used gzip method. We present a novel reference-free method meant to compress data issued from high throughput sequencing technologies. Our approach, implemented in the software LEON, employs techniques derived from existing assembly principles. The method is based on a reference probabilistic de Bruijn Graph, built de novo from the set of reads and stored in a Bloom filter. Each read is encoded as a path in this graph, by memorizing an anchoring kmer and a list of bifurcations. The same probabilistic de Bruijn Graph is used to perform a lossy transformation of the quality scores, which allows to obtain higher compression rates without losing pertinent information for downstream analyses. LEON was run on various real sequencing datasets (whole genome, exome, RNA-seq or metagenomics). In all cases, LEON showed higher overall compression ratios than state-of-the-art compression software. On a C. elegans whole genome sequencing dataset, LEON divided the original file size by more than 20. LEON is an open source software, distributed under GNU affero GPL License, available for download at http://gatb.inria.fr/software/leon/.

The compressed breast during mammography and breast tomosynthesis: in vivo shape characterization and modeling

NASA Astrophysics Data System (ADS)

Rodríguez-Ruiz, Alejandro; Agasthya, Greeshma A.; Sechopoulos, Ioannis

2017-09-01

To characterize and develop a patient-based 3D model of the compressed breast undergoing mammography and breast tomosynthesis. During this IRB-approved, HIPAA-compliant study, 50 women were recruited to undergo 3D breast surface imaging with structured light (SL) during breast compression, along with simultaneous acquisition of a tomosynthesis image. A pair of SL systems were used to acquire 3D surface images by projecting 24 different patterns onto the compressed breast and capturing their reflection off the breast surface in approximately 12-16 s. The 3D surface was characterized and modeled via principal component analysis. The resulting surface model was combined with a previously developed 2D model of projected compressed breast shapes to generate a full 3D model. Data from ten patients were discarded due to technical problems during image acquisition. The maximum breast thickness (found at the chest-wall) had an average value of 56 mm, and decreased 13% towards the nipple (breast tilt angle of 5.2°). The portion of the breast not in contact with the compression paddle or the support table extended on average 17 mm, 18% of the chest-wall to nipple distance. The outermost point along the breast surface lies below the midline of the total thickness. A complete 3D model of compressed breast shapes was created and implemented as a software application available for download, capable of generating new random realistic 3D shapes of breasts undergoing compression. Accurate characterization and modeling of the breast curvature and shape was achieved and will be used for various image processing and clinical tasks.

QualComp: a new lossy compressor for quality scores based on rate distortion theory

PubMed Central

2013-01-01

Background Next Generation Sequencing technologies have revolutionized many fields in biology by reducing the time and cost required for sequencing. As a result, large amounts of sequencing data are being generated. A typical sequencing data file may occupy tens or even hundreds of gigabytes of disk space, prohibitively large for many users. This data consists of both the nucleotide sequences and per-base quality scores that indicate the level of confidence in the readout of these sequences. Quality scores account for about half of the required disk space in the commonly used FASTQ format (before compression), and therefore the compression of the quality scores can significantly reduce storage requirements and speed up analysis and transmission of sequencing data. Results In this paper, we present a new scheme for the lossy compression of the quality scores, to address the problem of storage. Our framework allows the user to specify the rate (bits per quality score) prior to compression, independent of the data to be compressed. Our algorithm can work at any rate, unlike other lossy compression algorithms. We envisage our algorithm as being part of a more general compression scheme that works with the entire FASTQ file. Numerical experiments show that we can achieve a better mean squared error (MSE) for small rates (bits per quality score) than other lossy compression schemes. For the organism PhiX, whose assembled genome is known and assumed to be correct, we show that it is possible to achieve a significant reduction in size with little compromise in performance on downstream applications (e.g., alignment). Conclusions QualComp is an open source software package, written in C and freely available for download at https://sourceforge.net/projects/qualcomp. PMID:23758828

Data compression/error correction digital test system. Appendix 3: Maintenance. Book 2: Receiver assembly drawings

NASA Technical Reports Server (NTRS)

1972-01-01

The assembly drawings of the receiver unit are presented for the data compression/error correction digital test system. Equipment specifications are given for the various receiver parts, including the TV input buffer register, delta demodulator, TV sync generator, memory devices, and data storage devices.

Compressed Air Quality, A Case Study In Paiton Coal Fired Power Plant Unit 1 And 2

NASA Astrophysics Data System (ADS)

Indah, Nur; Kusuma, Yuriadi; Mardani

2018-03-01

The compressed air system becomes part of a very important utility system in a Plant, including the Steam Power Plant. In PLN’S coal fired power plant, Paiton units 1 and 2, there are four Centrifugal air compressor types, which produce compressed air as much as 5.652 cfm and with electric power capacity of 1200 kW. Electricity consumption to operate centrifugal compressor is 7.104.117 kWh per year. Compressed air generation is not only sufficient in quantity (flow rate) but also meets the required air quality standards. compressed air at Steam Power Plant is used for; service air, Instrument air, and for fly Ash. This study aims to measure some important parameters related to air quality, followed by potential disturbance analysis, equipment breakdown or reduction of energy consumption from existing compressed air conditions. These measurements include counting the number of dust particles, moisture content, relative humidity, and also compressed air pressure. From the measurements, the compressed air pressure generated by the compressor is about 8.4 barg and decreased to 7.7 barg at the furthest point, so the pressure drop is 0.63 barg, this number satisfies the needs in the end user. The measurement of the number of particles contained in compressed air, for particle of 0.3 micron reaches 170,752 particles, while for the particle size 0.5 micron reaches 45,245 particles. Measurements of particles conducted at several points of measurement. For some point measurements the number of dust particle exceeds the standard set by ISO 8573.1-2010 and also NACE Code, so it needs to be improved on the air treatment process. To see the amount of moisture content in compressed air, it is done by measuring pressure dew point temperature (PDP). Measurements were made at several points with results ranging from -28.4 to 30.9 °C. The recommendation of improving compressed air quality in steam power plant, Paiton unit 1 and 2 has the potential to extend the life of instrumentation equipment, improve the reliability of equipment, and reduce the amount of energy consumption up to 502,579 kWh per year.

Experimental Design of a Magnetic Flux Compression Experiment

NASA Astrophysics Data System (ADS)

Fuelling, Stephan; Awe, Thomas J.; Bauer, Bruno S.; Goodrich, Tasha; Lindemuth, Irvin R.; Makhin, Volodymyr; Siemon, Richard E.; Atchison, Walter L.; Reinovsky, Robert E.; Salazar, Mike A.; Scudder, David W.; Turchi, Peter J.; Degnan, James H.; Ruden, Edward L.

2007-06-01

Generation of ultrahigh magnetic fields is an interesting topic of high-energy-density physics, and an essential aspect of Magnetized Target Fusion (MTF). To examine plasma formation from conductors impinged upon by ultrahigh magnetic fields, in a geometry similar to that of the MAGO experiments, an experiment is under design to compress magnetic flux in a toroidal cavity, using the Shiva Star or Atlas generator. An initial toroidal bias magnetic field is provided by a current on a central conductor. The central current is generated by diverting a fraction of the liner current using an innovative inductive current divider, thus avoiding the need for an auxiliary power supply. A 50-mm-radius cylindrical aluminum liner implodes along glide planes with velocity of about 5 km/s. Inward liner motion causes electrical closure of the toroidal chamber, after which flux in the chamber is conserved and compressed, yielding magnetic fields of 2-3 MG. Plasma is generated on the liner and central rod surfaces by Ohmic heating. Diagnostics include B-dot probes, Faraday rotation, radiography, filtered photodiodes, and VUV spectroscopy. Optical access to the chamber is provided through small holes in the walls.

Detonation duct gas generator demonstration program

NASA Technical Reports Server (NTRS)

Wortman, Andrew; Brinlee, Gayl A.; Othmer, Peter; Whelan, Michael A.

1991-01-01

The feasibility of the generation of detonation waves moving periodically across high speed channel flow is experimentally demonstrated. Such waves are essential to the concept of compressing requirements and increasing the engine pressure compressor with the objective of reducing conventional compressor requirements and increasing the engine thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock wave losses are reduced by an order of magnitude. The ultimate objective is to use such detonation ducts downstream of a low pressure gas turbine compressor to produce a high overall pressure ratio thermodynamic cycle. A 4 foot long, 1 inch x 12 inch cross-section, detonation duct was operated in a blow-down mode using compressed air reservoirs. Liquid or vapor propane was injected through injectors or solenoid valves located in the plenum or the duct itself. Detonation waves were generated when the mixture was ignited by a row of spark plugs in the duct wall. Problems with fuel injection and mixing limited the air speeds to about Mach 0.5, frequencies to below 10 Hz, and measured pressure ratios of about 5 to 6. The feasibility of the gas dynamic compression was demonstrated and the critical problem areas were identified.

Subjective evaluation of compressed image quality

NASA Astrophysics Data System (ADS)

Lee, Heesub; Rowberg, Alan H.; Frank, Mark S.; Choi, Hyung-Sik; Kim, Yongmin

1992-05-01

Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine x-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 10:1, and 15:1. The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10:1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.

Progress with lossy compression of data from the Community Earth System Model

NASA Astrophysics Data System (ADS)

Xu, H.; Baker, A.; Hammerling, D.; Li, S.; Clyne, J.

2017-12-01

Climate models, such as the Community Earth System Model (CESM), generate massive quantities of data, particularly when run at high spatial and temporal resolutions. The burden of storage is further exacerbated by creating large ensembles, generating large numbers of variables, outputting at high frequencies, and duplicating data archives (to protect against disk failures). Applying lossy compression methods to CESM datasets is an attractive means of reducing data storage requirements, but ensuring that the loss of information does not negatively impact science objectives is critical. In particular, test methods are needed to evaluate whether critical features (e.g., extreme values and spatial and temporal gradients) have been preserved and to boost scientists' confidence in the lossy compression process. We will provide an overview on our progress in applying lossy compression to CESM output and describe our unique suite of metric tests that evaluate the impact of information loss. Further, we will describe our processes how to choose an appropriate compression algorithm (and its associated parameters) given the diversity of CESM data (e.g., variables may be constant, smooth, change abruptly, contain missing values, or have large ranges). Traditional compression algorithms, such as those used for images, are not necessarily ideally suited for floating-point climate simulation data, and different methods may have different strengths and be more effective for certain types of variables than others. We will discuss our progress towards our ultimate goal of developing an automated multi-method parallel approach for compression of climate data that both maximizes data reduction and minimizes the impact of data loss on science results.

Turbulence and vorticity in Galaxy clusters generated by structure formation

NASA Astrophysics Data System (ADS)

Vazza, F.; Jones, T. W.; Brüggen, M.; Brunetti, G.; Gheller, C.; Porter, D.; Ryu, D.

2017-01-01

Turbulence is a key ingredient for the evolution of the intracluster medium, whose properties can be predicted with high-resolution numerical simulations. We present initial results on the generation of solenoidal and compressive turbulence in the intracluster medium during the formation of a small-size cluster using highly resolved, non-radiative cosmological simulations, with a refined monitoring in time. In this first of a series of papers, we closely look at one simulated cluster whose formation was distinguished by a merger around z ˜ 0.3. We separate laminar gas motions, turbulence and shocks with dedicated filtering strategies and distinguish the solenoidal and compressive components of the gas flows using Hodge-Helmholtz decomposition. Solenoidal turbulence dominates the dissipation of turbulent motions (˜95 per cent) in the central cluster volume at all epochs. The dissipation via compressive modes is found to be more important (˜30 per cent of the total) only at large radii (≥0.5rvir) and close to merger events. We show that enstrophy (vorticity squared) is good proxy of solenoidal turbulence. All terms ruling the evolution of enstrophy (I.e. baroclinic, compressive, stretching and advective terms) are found to be significant, but in amounts that vary with time and location. Two important trends for the growth of enstrophy in our simulation are identified: first, enstrophy is continuously accreted into the cluster from the outside, and most of that accreted enstrophy is generated near the outer accretion shocks by baroclinic and compressive processes. Secondly, in the cluster interior vortex, stretching is dominant, although the other terms also contribute substantially.

Analysis and testing of axial compression in imperfect slender truss struts

NASA Technical Reports Server (NTRS)

Lake, Mark S.; Georgiadis, Nicholas

1990-01-01

The axial compression of imperfect slender struts for large space structures is addressed. The load-shortening behavior of struts with initially imperfect shapes and eccentric compressive end loading is analyzed using linear beam-column theory and results are compared with geometrically nonlinear solutions to determine the applicability of linear analysis. A set of developmental aluminum clad graphite/epoxy struts sized for application to the Space Station Freedom truss are measured to determine their initial imperfection magnitude, load eccentricity, and cross sectional area and moment of inertia. Load-shortening curves are determined from axial compression tests of these specimens and are correlated with theoretical curves generated using linear analysis.

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

Schlanderer, Stefan C., E-mail: stefan.schlanderer@unimelb.edu.au; Weymouth, Gabriel D., E-mail: G.D.Weymouth@soton.ac.uk; Sandberg, Richard D., E-mail: richard.sandberg@unimelb.edu.au

This paper introduces a virtual boundary method for compressible viscous fluid flow that is capable of accurately representing moving bodies in flow and aeroacoustic simulations. The method is the compressible extension of the boundary data immersion method (BDIM, Maertens & Weymouth (2015), ). The BDIM equations for the compressible Navier–Stokes equations are derived and the accuracy of the method for the hydrodynamic representation of solid bodies is demonstrated with challenging test cases, including a fully turbulent boundary layer flow and a supersonic instability wave. In addition we show that the compressible BDIM is able to accurately represent noise radiation frommore » moving bodies and flow induced noise generation without any penalty in allowable time step.« less

Nonlinear compression of temporal solitons in an optical waveguide via inverse engineering

NASA Astrophysics Data System (ADS)

Paul, Koushik; Sarma, Amarendra K.

2018-03-01

We propose a novel method based on the so-called shortcut-to-adiabatic passage techniques to achieve fast compression of temporal solitons in a nonlinear waveguide. We demonstrate that soliton compression could be achieved, in principle, at an arbitrarily small distance by inverse-engineering the pulse width and the nonlinearity of the medium. The proposed scheme could possibly be exploited for various short-distance communication protocols and may be even in nonlinear guided wave-optics devices and generation of ultrashort soliton pulses.

A Novel 2D Image Compression Algorithm Based on Two Levels DWT and DCT Transforms with Enhanced Minimize-Matrix-Size Algorithm for High Resolution Structured Light 3D Surface Reconstruction

NASA Astrophysics Data System (ADS)

Siddeq, M. M.; Rodrigues, M. A.

2015-09-01

Image compression techniques are widely used on 2D image 2D video 3D images and 3D video. There are many types of compression techniques and among the most popular are JPEG and JPEG2000. In this research, we introduce a new compression method based on applying a two level discrete cosine transform (DCT) and a two level discrete wavelet transform (DWT) in connection with novel compression steps for high-resolution images. The proposed image compression algorithm consists of four steps. (1) Transform an image by a two level DWT followed by a DCT to produce two matrices: DC- and AC-Matrix, or low and high frequency matrix, respectively, (2) apply a second level DCT on the DC-Matrix to generate two arrays, namely nonzero-array and zero-array, (3) apply the Minimize-Matrix-Size algorithm to the AC-Matrix and to the other high-frequencies generated by the second level DWT, (4) apply arithmetic coding to the output of previous steps. A novel decompression algorithm, Fast-Match-Search algorithm (FMS), is used to reconstruct all high-frequency matrices. The FMS-algorithm computes all compressed data probabilities by using a table of data, and then using a binary search algorithm for finding decompressed data inside the table. Thereafter, all decoded DC-values with the decoded AC-coefficients are combined in one matrix followed by inverse two levels DCT with two levels DWT. The technique is tested by compression and reconstruction of 3D surface patches. Additionally, this technique is compared with JPEG and JPEG2000 algorithm through 2D and 3D root-mean-square-error following reconstruction. The results demonstrate that the proposed compression method has better visual properties than JPEG and JPEG2000 and is able to more accurately reconstruct surface patches in 3D.

smallWig: parallel compression of RNA-seq WIG files.

PubMed

Wang, Zhiying; Weissman, Tsachy; Milenkovic, Olgica

2016-01-15

We developed a new lossless compression method for WIG data, named smallWig, offering the best known compression rates for RNA-seq data and featuring random access functionalities that enable visualization, summary statistics analysis and fast queries from the compressed files. Our approach results in order of magnitude improvements compared with bigWig and ensures compression rates only a fraction of those produced by cWig. The key features of the smallWig algorithm are statistical data analysis and a combination of source coding methods that ensure high flexibility and make the algorithm suitable for different applications. Furthermore, for general-purpose file compression, the compression rate of smallWig approaches the empirical entropy of the tested WIG data. For compression with random query features, smallWig uses a simple block-based compression scheme that introduces only a minor overhead in the compression rate. For archival or storage space-sensitive applications, the method relies on context mixing techniques that lead to further improvements of the compression rate. Implementations of smallWig can be executed in parallel on different sets of chromosomes using multiple processors, thereby enabling desirable scaling for future transcriptome Big Data platforms. The development of next-generation sequencing technologies has led to a dramatic decrease in the cost of DNA/RNA sequencing and expression profiling. RNA-seq has emerged as an important and inexpensive technology that provides information about whole transcriptomes of various species and organisms, as well as different organs and cellular communities. The vast volume of data generated by RNA-seq experiments has significantly increased data storage costs and communication bandwidth requirements. Current compression tools for RNA-seq data such as bigWig and cWig either use general-purpose compressors (gzip) or suboptimal compression schemes that leave significant room for improvement. To substantiate 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.

Distributed Coding of Compressively Sensed Sources

NASA Astrophysics Data System (ADS)

Goukhshtein, Maxim

In this work we propose a new method for compressing multiple correlated sources with a very low-complexity encoder in the presence of side information. Our approach uses ideas from compressed sensing and distributed source coding. At the encoder, syndromes of the quantized compressively sensed sources are generated and transmitted. The decoder uses side information to predict the compressed sources. The predictions are then used to recover the quantized measurements via a two-stage decoding process consisting of bitplane prediction and syndrome decoding. Finally, guided by the structure of the sources and the side information, the sources are reconstructed from the recovered measurements. As a motivating example, we consider the compression of multispectral images acquired on board satellites, where resources, such as computational power and memory, are scarce. Our experimental results exhibit a significant improvement in the rate-distortion trade-off when compared against approaches with similar encoder complexity.

Free-beam soliton self-compression in air

NASA Astrophysics Data System (ADS)

Voronin, A. A.; Mitrofanov, A. V.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Pugžlys, A.; Panchenko, V. Ya; Shumakova, V.; Ališauskas, S.; Baltuška, A.; Zheltikov, A. M.

2018-02-01

We identify a physical scenario whereby soliton transients generated in freely propagating laser beams within the regions of anomalous dispersion in air can be compressed as a part of their free-beam spatiotemporal evolution to yield few-cycle mid- and long-wavelength-infrared field waveforms, whose peak power is substantially higher than the peak power of the input pulses. We show that this free-beam soliton self-compression scenario does not require ionization or laser-induced filamentation, enabling high-throughput self-compression of mid- and long-wavelength-infrared laser pulses within a broad range of peak powers from tens of gigawatts up to the terawatt level. We also demonstrate that this method of pulse compression can be extended to long-range propagation, providing self-compression of high-peak-power laser pulses in atmospheric air within propagation ranges as long as hundreds of meters, suggesting new ways towards longer-range standoff detection and remote sensing.

Interactive computer graphics applications for compressible aerodynamics

NASA Technical Reports Server (NTRS)

Benson, Thomas J.

1994-01-01

Three computer applications have been developed to solve inviscid compressible fluids problems using interactive computer graphics. The first application is a compressible flow calculator which solves for isentropic flow, normal shocks, and oblique shocks or centered expansions produced by two dimensional ramps. The second application couples the solutions generated by the first application to a more graphical presentation of the results to produce a desk top simulator of three compressible flow problems: 1) flow past a single compression ramp; 2) flow past two ramps in series; and 3) flow past two opposed ramps. The third application extends the results of the second to produce a design tool which solves for the flow through supersonic external or mixed compression inlets. The applications were originally developed to run on SGI or IBM workstations running GL graphics. They are currently being extended to solve additional types of flow problems and modified to operate on any X-based workstation.

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

NASA Astrophysics Data System (ADS)

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.

Effects of video compression on target acquisition performance

NASA Astrophysics Data System (ADS)

Espinola, Richard L.; Cha, Jae; Preece, Bradley

2008-04-01

The bandwidth requirements of modern target acquisition systems continue to increase with larger sensor formats and multi-spectral capabilities. To obviate this problem, still and moving imagery can be compressed, often resulting in greater than 100 fold decrease in required bandwidth. Compression, however, is generally not error-free and the generated artifacts can adversely affect task performance. The U.S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate recently performed an assessment of various compression techniques on static imagery for tank identification. In this paper, we expand this initial assessment by studying and quantifying the effect of various video compression algorithms and their impact on tank identification performance. We perform a series of controlled human perception tests using three dynamic simulated scenarios: target moving/sensor static, target static/sensor static, sensor tracking the target. Results of this study will quantify the effect of video compression on target identification and provide a framework to evaluate video compression on future sensor systems.

Free-piston engine

DOEpatents

Van Blarigan, Peter

2001-01-01

A combustion system which can utilize high compression ratios, short burn durations, and homogeneous fuel/air mixtures in conjunction with low equivalence ratios. In particular, a free-piston, two-stroke autoignition internal combustion engine including an electrical generator having a linear alternator with a double-ended free piston that oscillates inside a closed cylinder is provided. Fuel and air are introduced in a two-stroke cycle fashion on each end, where the cylinder charge is compressed to the point of autoignition without spark plugs. The piston is driven in an oscillating motion as combustion occurs successively on each end. This leads to rapid combustion at almost constant volume for any fuel/air equivalence ratio mixture at very high compression ratios. The engine is characterized by high thermal efficiency and low NO.sub.x emissions. The engine is particularly suited for generating electrical current in a hybrid automobile.

Contour forming of metals by laser peening

DOEpatents

Hackel, Lloyd; Harris, Fritz

2002-01-01

A method and apparatus are provided for forming shapes and contours in metal sections by generating laser induced compressive stress on the surface of the metal workpiece. The laser process can generate deep compressive stresses to shape even thick components without inducing unwanted tensile stress at the metal surface. The precision of the laser-induced stress enables exact prediction and subsequent contouring of parts. A light beam of 10 to 100 J/pulse is imaged to create an energy fluence of 60 to 200 J/cm.sup.2 on an absorptive layer applied over a metal surface. A tamping layer of water is flowed over the absorptive layer. The absorption of laser light causes a plasma to form and consequently creates a shock wave that induces a deep residual compressive stress into the metal. The metal responds to this residual stress by bending.

Vector generator scan converter

DOEpatents

Moore, James M.; Leighton, James F.

1990-01-01

High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

Vector generator scan converter

DOEpatents

Moore, J.M.; Leighton, J.F.

1988-02-05

High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

Method for compression of binary data

DOEpatents

Berlin, Gary J.

1996-01-01

The disclosed method for compression of a series of data bytes, based on LZSS-based compression methods, provides faster decompression of the stored data. The method involves the creation of a flag bit buffer in a random access memory device for temporary storage of flag bits generated during normal LZSS-based compression. The flag bit buffer stores the flag bits separately from their corresponding pointers and uncompressed data bytes until all input data has been read. Then, the flag bits are appended to the compressed output stream of data. Decompression can be performed much faster because bit manipulation is only required when reading the flag bits and not when reading uncompressed data bytes and pointers. Uncompressed data is read using byte length instructions and pointers are read using word instructions, thus reducing the time required for decompression.

Towards Natural Transition in Compressible Boundary Layers

DTIC Science & Technology

2016-06-29

Behaviour of a natural laminar flow aerofoil in flight through atmospheric turbulence. Journal of Fluid Mechanics, 767:394–429, 003 2015. [70] O...DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited See report Wave packet, compressible boundary layer, subsonic flow ...Base flow generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.1.1 Boundary layer profiles

Compression of Index Term Dictionary in an Inverted-File-Oriented Database: Some Effective Algorithms.

ERIC Educational Resources Information Center

Wisniewski, Janusz L.

1986-01-01

Discussion of a new method of index term dictionary compression in an inverted-file-oriented database highlights a technique of word coding, which generates short fixed-length codes obtained from the index terms themselves by analysis of monogram and bigram statistical distributions. Substantial savings in communication channel utilization are…

Pressure mapping and performance of the compression bandage/garment for venous leg ulcer treatment.

PubMed

Ghosh, S; Mukhopadhyay, A; Sikka, M; Nagla, K S

2008-08-01

A study has been conducted on the commercially available compression bandages as regards their performance with time. Pressure mapping of these bandages has been done using a fabricated pressure-measuring device on a mannequin leg to see the effect on pressure due to creep, fabric friction and angle of bandaging. The results show that the creep behavior, frictional behavior and the angle of bandaging have a significant effect on the pressure profile generated by the bandages during application. The regression analysis shows that the surface friction restricts the slippage in a multilayer system. Also the diameters of the limb and the amount of stretch given to the bandage during application have definite impact on the bandage pressure. In case of compression garments, washing improves the pressure generated but not to the extent of the pressure of a virgin garment. Comparing the two compression materials i.e. bandage and garment, it is found that the presence of higher percentage of elastomeric material and a highly close construction in case of garment provides better holding power and a more homogeneous pressure distribution.

A Modified Split Hopkinson Pressure Bar Approach for Mimicking Dynamic Oscillatory Stress Fluctuations During Earthquake Rupture

NASA Astrophysics Data System (ADS)

Braunagel, M. J.; Griffith, W. A.

2017-12-01

Past experimental work has demonstrated that rock failure at high strain rates occurs by fragmentation rather than discrete fracture and is accompanied by a dramatic increase in rock strength. However, these observations are difficult to reconcile with the assertion that pulverized rocks in fault zones are the product of impulsive stresses during the passage of earthquake ruptures, as the distance from the principal slip zones of some pulverized rock is too great to exceed fragmentation transition. One potential explanation to this paradox that has been suggested is that repeated loading over the course of multiple earthquake ruptures may gradually reduce the pulverization threshold, in terms of both strain rate and strength. We propose that oscillatory loading during a single earthquake rupture may further lower these pulverization thresholds, and that traditional dynamic experimental approaches, such as the Split Hopkinson Pressure Bar (SHPB) wherein load is applied as a single, smooth, sinusoidal compressive wave, may not reflect natural loading conditions. To investigate the effects of oscillatory compressive loading expected during earthquake rupture propagation, we develop a controlled cyclic loading model on a SHPB apparatus utilizing two striker bars connected by an elastic spring. Unlike traditional SHPB experiments that utilize a gas gun to fire a projectile bar and generate a single compressive wave on impact with the incident bar, our modified striker bar assembly oscillates while moving down the gun barrel and generates two separate compressive pulses separated by a lag time. By modeling the modified assembly as a mass-spring-mass assembly accelerating due to the force of the released gas, we can predict the compression time of the spring upon impact and therefore the time delay between the generation of the first and second compressive waves. This allows us to predictably control load cycles with durations of only a few hundred microseconds. Initial experimental results demonstrate that fragmentation of Westerly Granite samples occurs at lower stresses and strain rates than those expected from traditional SHPB experiments.

FRESCO: Referential compression of highly similar sequences.

PubMed

Wandelt, Sebastian; Leser, Ulf

2013-01-01

In many applications, sets of similar texts or sequences are of high importance. Prominent examples are revision histories of documents or genomic sequences. Modern high-throughput sequencing technologies are able to generate DNA sequences at an ever-increasing rate. In parallel to the decreasing experimental time and cost necessary to produce DNA sequences, computational requirements for analysis and storage of the sequences are steeply increasing. Compression is a key technology to deal with this challenge. Recently, referential compression schemes, storing only the differences between a to-be-compressed input and a known reference sequence, gained a lot of interest in this field. In this paper, we propose a general open-source framework to compress large amounts of biological sequence data called Framework for REferential Sequence COmpression (FRESCO). Our basic compression algorithm is shown to be one to two orders of magnitudes faster than comparable related work, while achieving similar compression ratios. We also propose several techniques to further increase compression ratios, while still retaining the advantage in speed: 1) selecting a good reference sequence; and 2) rewriting a reference sequence to allow for better compression. In addition,we propose a new way of further boosting the compression ratios by applying referential compression to already referentially compressed files (second-order compression). This technique allows for compression ratios way beyond state of the art, for instance,4,000:1 and higher for human genomes. We evaluate our algorithms on a large data set from three different species (more than 1,000 genomes, more than 3 TB) and on a collection of versions of Wikipedia pages. Our results show that real-time compression of highly similar sequences at high compression ratios is possible on modern hardware.

Method for data compression by associating complex numbers with files of data values

DOEpatents

Feo, J.T.; Hanks, D.C.; Kraay, T.A.

1998-02-10

A method for compressing data for storage or transmission is disclosed. Given a complex polynomial and a value assigned to each root, a root generated data file (RGDF) is created, one entry at a time. Each entry is mapped to a point in a complex plane. An iterative root finding technique is used to map the coordinates of the point to the coordinates of one of the roots of the polynomial. The value associated with that root is assigned to the entry. An equational data compression (EDC) method reverses this procedure. Given a target data file, the EDC method uses a search algorithm to calculate a set of m complex numbers and a value map that will generate the target data file. The error between a simple target data file and generated data file is typically less than 10%. Data files can be transmitted or stored without loss by transmitting the m complex numbers, their associated values, and an error file whose size is at most one-tenth of the size of the input data file. 4 figs.

On predicting receptivity to surface roughness in a compressible infinite swept wing boundary layer

NASA Astrophysics Data System (ADS)

Thomas, Christian; Mughal, Shahid; Ashworth, Richard

2017-03-01

The receptivity of crossflow disturbances on an infinite swept wing is investigated using solutions of the adjoint linearised Navier-Stokes equations. The adjoint based method for predicting the magnitude of stationary disturbances generated by randomly distributed surface roughness is described, with the analysis extended to include both surface curvature and compressible flow effects. Receptivity is predicted for a broad spectrum of spanwise wavenumbers, variable freestream Reynolds numbers, and subsonic Mach numbers. Curvature is found to play a significant role in the receptivity calculations, while compressible flow effects are only found to marginally affect the initial size of the crossflow instability. A Monte Carlo type analysis is undertaken to establish the mean amplitude and variance of crossflow disturbances generated by the randomly distributed surface roughness. Mean amplitudes are determined for a range of flow parameters that are maximised for roughness distributions containing a broad spectrum of roughness wavelengths, including those that are most effective in generating stationary crossflow disturbances. A control mechanism is then developed where the short scale roughness wavelengths are damped, leading to significant reductions in the receptivity amplitude.

Method for data compression by associating complex numbers with files of data values

DOEpatents

Feo, John Thomas; Hanks, David Carlton; Kraay, Thomas Arthur

1998-02-10

A method for compressing data for storage or transmission. Given a complex polynomial and a value assigned to each root, a root generated data file (RGDF) is created, one entry at a time. Each entry is mapped to a point in a complex plane. An iterative root finding technique is used to map the coordinates of the point to the coordinates of one of the roots of the polynomial. The value associated with that root is assigned to the entry. An equational data compression (EDC) method reverses this procedure. Given a target data file, the EDC method uses a search algorithm to calculate a set of m complex numbers and a value map that will generate the target data file. The error between a simple target data file and generated data file is typically less than 10%. Data files can be transmitted or stored without loss by transmitting the m complex numbers, their associated values, and an error file whose size is at most one-tenth of the size of the input data file.

Ponderomotive Generation and Detection of Attosecond Free-Electron Pulse Trains

NASA Astrophysics Data System (ADS)

Kozák, M.; Schönenberger, N.; Hommelhoff, P.

2018-03-01

Atomic motion dynamics during structural changes or chemical reactions have been visualized by pico- and femtosecond pulsed electron beams via ultrafast electron diffraction and microscopy. Imaging the even faster dynamics of electrons in atoms, molecules, and solids requires electron pulses with subfemtosecond durations. We demonstrate here the all-optical generation of trains of attosecond free-electron pulses. The concept is based on the periodic energy modulation of a pulsed electron beam via an inelastic interaction, with the ponderomotive potential of an optical traveling wave generated by two femtosecond laser pulses at different frequencies in vacuum. The subsequent dispersive propagation leads to a compression of the electrons and the formation of ultrashort pulses. The longitudinal phase space evolution of the electrons after compression is mapped by a second phase-locked interaction. The comparison of measured and calculated spectrograms reveals the attosecond temporal structure of the compressed electron pulse trains with individual pulse durations of less than 300 as. This technique can be utilized for tailoring and initial characterization of suboptical-cycle free-electron pulses at high repetition rates for stroboscopic time-resolved experiments with subfemtosecond time resolution.

High-quality JPEG compression history detection for fake uncompressed images

NASA Astrophysics Data System (ADS)

Zhang, Rong; Wang, Rang-Ding; Guo, Li-Jun; Jiang, Bao-Chuan

2017-05-01

Authenticity is one of the most important evaluation factors of images for photography competitions or journalism. Unusual compression history of an image often implies the illicit intent of its author. Our work aims at distinguishing real uncompressed images from fake uncompressed images that are saved in uncompressed formats but have been previously compressed. To detect the potential image JPEG compression, we analyze the JPEG compression artifacts based on the tetrolet covering, which corresponds to the local image geometrical structure. Since the compression can alter the structure information, the tetrolet covering indexes may be changed if a compression is performed on the test image. Such changes can provide valuable clues about the image compression history. To be specific, the test image is first compressed with different quality factors to generate a set of temporary images. Then, the test image is compared with each temporary image block-by-block to investigate whether the tetrolet covering index of each 4×4 block is different between them. The percentages of the changed tetrolet covering indexes corresponding to the quality factors (from low to high) are computed and used to form the p-curve, the local minimum of which may indicate the potential compression. Our experimental results demonstrate the advantage of our method to detect JPEG compressions of high quality, even the highest quality factors such as 98, 99, or 100 of the standard JPEG compression, from uncompressed-format images. At the same time, our detection algorithm can accurately identify the corresponding compression quality factor.

Simulation of supersonic turbulent flow in the vicinity of an inclined backward-facing step

NASA Astrophysics Data System (ADS)

El-Askary, W. A.

2011-08-01

Large eddy simulation (LES) is a viable and powerful tool to analyse unsteady three-dimensional turbulent flows. In this article, the method of LES is used to compute a plane turbulent supersonic boundary layer subjected to different pressure gradients. The pressure gradients are generated by allowing the flow to pass in the vicinity of an expansion-compression ramp (inclined backward-facing step with leeward-face angle of 25°) for an upstream Mach number of 2.9. The inflow boundary condition is the main problem for all turbulent wall-bounded flows. An approach to solve this problem is to extract instantaneous velocities, temperature and density data from an auxiliary simulation (inflow generator). To generate an appropriate realistic inflow condition to the inflow generator itself the rescaling technique for compressible flows is used. In this method, Morkovin's hypothesis, in which the total temperature fluctuations are neglected compared with the static temperature fluctuations, is applied to rescale and generate the temperature profile at inlet. This technique was successfully developed and applied by the present author for an LES of subsonic three-dimensional boundary layer of a smooth curved ramp. The present LES results are compared with the available experimental data as well as numerical data. The positive impact of the rescaling formulation of the temperature is proven by the convincing agreement of the obtained results with the experimental data compared with published numerical work and sheds light on the quality of the developed compressible inflow generator.

Electron dynamics in high energy density plasma bunch generation driven by intense picosecond laser pulse

NASA Astrophysics Data System (ADS)

Li, M.; Yuan, T.; Xu, Y. X.; Luo, S. N.

2018-05-01

When an intense picosecond laser pulse is loaded upon a dense plasma, a high energy density plasma bunch, including electron bunch and ion bunch, can be generated in the target. We simulate this process through one-dimensional particle-in-cell simulation and find that the electron bunch generation is mainly due to a local high energy density electron sphere originated in the plasma skin layer. Once generated the sphere rapidly expands to compress the surrounding electrons and induce high density electron layer, coupled with that, hot electrons are efficiently triggered in the local sphere and traveling in the whole target. Under the compressions of light pressure, forward-running and backward-running hot electrons, a high energy density electron bunch generates. The bunch energy density is as high as TJ/m3 order of magnitude in our conditions, which is significant in laser driven dynamic high pressure generation and may find applications in high energy density physics.

Apparatus for measuring tensile and compressive properties of solid materials at cryogenic temperatures

DOEpatents

Gonczy, John D.; Markley, Finley W.; McCaw, William R.; Niemann, Ralph C.

1992-01-01

An apparatus for evaluating the tensile and compressive properties of material samples at very low or cryogenic temperatures employs a stationary frame and a dewar mounted below the frame. A pair of coaxial cylindrical tubes extend downward towards the bottom of the dewar. A compressive or tensile load is generated hydraulically and is transmitted by the inner tube to the material sample. The material sample is located near the bottom of the dewar in a liquid refrigerant bath. The apparatus employs a displacement measuring device, such as a linear variable differential transformer, to measure the deformation of the material sample relative to the amount of compressive or tensile force applied to the sample.

Laser chirp effect on femtosecond laser filamentation generated for pulse compression.

PubMed

Park, Juyun; Lee, Jae-Hwan; Nam, Chang H

2008-03-31

The influence of laser chirp on the formation of femtosecond laser filamentation in Ar was investigated for the generation of few-cycle high-power laser pulses. The condition for the formation of a single filament has been carefully examined using 28-fs laser pulses with energy over 3 mJ. The filament formation and output spectrum changed very sensitively to the initial laser chirp and gas pressure. Much larger spectral broadening was obtained with positively chirped pulses, compared to the case of negatively chirped pulses that generated much longer filament, and compressed pulses of 5.5 fs with energy of 0.5 mJ were obtained from the filamentation of positively chirped 30-fs laser pulses in a single Ar cell.

Progress in energy generation for Canadian remote sites

NASA Astrophysics Data System (ADS)

Saad, Y.; Younes, R.; Abboudi, S.; Ilinca, A.; Nohra, C.

2016-07-01

Many remote areas around the world are isolated, for various reasons, from electricity networks. They are usually supplied with electricity through diesel generators. The cost of operation and transportation of diesel fuel in addition to its price have led to the procurement of a more efficient and environmentally greener method of supply. Various studies have shown that a wind-diesel hybrid system with compressed air storage (WDCAS) seems to be one of the best solutions, and presents itself as an optimal configuration for the electrification of isolated sites. This system allows significant fuel savings to be made because the stored compressed air is used to supercharge the engine. In order to optimize system performance and minimize fuel consumption, installation of a system for recovering and storing the heat of compression (TES) seems necessary. In addition, the use of hydro-pneumatic energy storage systems that use the same machine as the hydraulic pump and turbine allow us to store energy in tight spaces and, if possible, contribute to power generation. The scrupulous study of this technical approach will be the focus of our research which will validate (or not) the use of such a system for the regulation of frequency of electrical networks. In this article we will skim through the main research that recently examined the wind-diesel hybrid system which addressed topics such as adiabatic compression and hydro-pneumatic storage. Instead, we will offer (based on existing studies) a new ACP-WDCAS (wind-diesel hybrid system with adiabatic air compression and storage at constant pressure), which combines these three concepts in one system for the optimization of wind-diesel hybrid system.

Ultrafast shock compression of self-assembled monolayers: a molecular picture.

PubMed

Patterson, James E; Dlott, Dana D

2005-03-24

Simulations of self-assembled monolayers (SAMs) are performed to interpret experimental measurements of ultrafast approximately 1 GPa (volume compression deltaV approximately 0.1) planar shock compression dynamics probed by vibrational sum-frequency generation (SFG) spectroscopy (Lagutchev, A. S.; Patterson, J. E.; Huang, W.; Dlott, D. D. J. Phys. Chem. B 2005, 109, XXXX). The SAMs investigated are octadecanethiol (ODT) and pentadecanethiol (PDT) on Au(111) and Ag(111) substrates, and benzyl mercaptan (BMT) on Au(111). In the alkane SAMs, SFG is sensitive to the instantaneous orientation of the terminal methyl; in BMT it is sensitive to the phenyl orientation. Computed structures of alkane SAMs are in good agreement with experiment. In alkanes, the energies of gauche defects increase with increasing number and depth below the methyl plane, with the exception of ODT/Au where both single and double gauche defects at the two uppermost dihedrals have similar energies. Simulations of isothermal uniaxial compression of SAM lattices show that chain and methyl tilting is predominant in PDT/Au, ODT/Ag and PDT/Ag, whereas single and double gauche defect formation is predominant in ODT/Au. Time-resolved shock data showing transient SFG signal loss of ODT/Au and PDT/Au are fit by calculations of the terminal group orientations as a function of deltaV and their contributions to the SFG hyperpolarizability. The highly elastic response of PDT/Au results from shock-generated methyl and chain tilting. The viscoelastic response of ODT/Au results from shock generation of single and double gauche defects. Isothermal compression simulations help explain and fit the time dependence of shock spectra but generally underestimate the magnitude of SFG signal loss because they do not include effects of high-strain-rate dynamics and shock front and surface irregularities.

Modelling deformation and fracture in confectionery wafers

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

Mohammed, Idris K.; Charalambides, Maria N.; Williams, J. Gordon

2015-01-22

The aim of this research is to model the deformation and fracture behaviour of brittle wafers often used in chocolate confectionary products. Three point bending and compression experiments were performed on beam and circular disc samples respectively to determine the 'apparent' stress-strain curves in bending and compression. The deformation of the wafer for both these testing types was observed in-situ within an SEM. The wafer is modeled analytically and numerically as a composite material with a core which is more porous than the skins. X-ray tomography was used to generate a three dimensional volume of the wafer microstructure which wasmore » then meshed and used for quantitative analysis. A linear elastic material model, with a damage function and element deletion, was used and the XMT generated architecture was loaded in compression. The output from the FE simulations correlates closely to the load-deflection deformation observed experimentally.« less

Design and the parametric testing of the space station prototype integrated vapor compression distillation water recovery module

NASA Technical Reports Server (NTRS)

Reveley, W. F.; Nuccio, P. P.

1975-01-01

Potable water for the Space Station Prototype life support system is generated by the vapor compression technique of vacuum distillation. A description of a complete three-man modular vapor compression water renovation loop that was built and tested is presented; included are all of the pumps, tankage, chemical post-treatment, instrumentation, and controls necessary to make the loop representative of an automatic, self-monitoring, null gravity system. The design rationale is given and the evolved configuration is described. Presented next are the results of an extensive parametric test during which distilled water was generated from urine and urinal flush water with concentration of solids in the evaporating liquid increasing progressively to 60 percent. Water quality, quantity and production rate are shown together with measured energy consumption rate in terms of watt-hours per kilogram of distilled water produced.

Compressed air-assisted solvent extraction (CASX) for metal removal.

PubMed

Li, Chi-Wang; Chen, Yi-Ming; Hsiao, Shin-Tien

2008-03-01

A novel process, compressed air-assisted solvent extraction (CASX), was developed to generate micro-sized solvent-coated air bubbles (MSAB) for metal extraction. Through pressurization of solvent with compressed air followed by releasing air-oversaturated solvent into metal-containing wastewater, MSAB were generated instantaneously. The enormous surface area of MSAB makes extraction process extremely fast and achieves very high aqueous/solvent weight ratio (A/S ratio). CASX process completely removed Cr(VI) from acidic electroplating wastewater under A/S ratio of 115 and extraction time of less than 10s. When synthetic wastewater containing Cd(II) of 50mgl(-1) was treated, A/S ratios of higher than 714 and 1190 could be achieved using solvent with extractant/diluent weight ratio of 1:1 and 5:1, respectively. Also, MSAB have very different physical properties, such as size and density, compared to the emulsified solvent droplets, making separation and recovery of solvent from treated effluent very easy.

Development of a Next-Generation Membrane-Integrated Adsorption Processor for CO2 Removal and Compression for Closed-Loop Air Revitalization Systems

NASA Technical Reports Server (NTRS)

Mulloth, Lila; LeVan, Douglas

2002-01-01

The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the concept of a next-generation, membrane integrated, adsorption processor for CO2 removal nd compression in closed-loop air revitalization systems. This processor will use many times less power than NASA's current CO2 removal technology and will be capable of maintaining a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems. The compact, consolidated, configuration of gas dryer, CO2 separator, and CO2 compressor will allow continuous recycling of humid air in the cabin and supply of compressed CO2 to the reduction unit for oxygen recovery. The device has potential application to the International Space Station and future, long duration, transit, and planetary missions.

Method and system for efficient video compression with low-complexity encoder

NASA Technical Reports Server (NTRS)

Chen, Jun (Inventor); He, Dake (Inventor); Sheinin, Vadim (Inventor); Jagmohan, Ashish (Inventor); Lu, Ligang (Inventor)

2012-01-01

Disclosed are a method and system for video compression, wherein the video encoder has low computational complexity and high compression efficiency. The disclosed system comprises a video encoder and a video decoder, wherein the method for encoding includes the steps of converting a source frame into a space-frequency representation; estimating conditional statistics of at least one vector of space-frequency coefficients; estimating encoding rates based on the said conditional statistics; and applying Slepian-Wolf codes with the said computed encoding rates. The preferred method for decoding includes the steps of; generating a side-information vector of frequency coefficients based on previously decoded source data, encoder statistics, and previous reconstructions of the source frequency vector; and performing Slepian-Wolf decoding of at least one source frequency vector based on the generated side-information, the Slepian-Wolf code bits and the encoder statistics.

Modelling deformation and fracture in confectionery wafers

NASA Astrophysics Data System (ADS)

Mohammed, Idris K.; Charalambides, Maria N.; Williams, J. Gordon; Rasburn, John

2015-01-01

The aim of this research is to model the deformation and fracture behaviour of brittle wafers often used in chocolate confectionary products. Three point bending and compression experiments were performed on beam and circular disc samples respectively to determine the 'apparent' stress-strain curves in bending and compression. The deformation of the wafer for both these testing types was observed in-situ within an SEM. The wafer is modeled analytically and numerically as a composite material with a core which is more porous than the skins. X-ray tomography was used to generate a three dimensional volume of the wafer microstructure which was then meshed and used for quantitative analysis. A linear elastic material model, with a damage function and element deletion, was used and the XMT generated architecture was loaded in compression. The output from the FE simulations correlates closely to the load-deflection deformation observed experimentally.

Influence of Rare-Earth Additions on Properties of Titanium Alloys - Effects of Yttrium and Erbium Additions on Ti-8Al and Ti-10Al Alloy.

DTIC Science & Technology

1980-08-31

loop generated during the alternate tension-compression fatigue testing of Ti-8A1 alloy at 6000C at a plastic strain amplitude of * 0.5Z...Dependence of peak stress on the number of cycles in the longitudinal orientation of Ti-lOAl-RE alloys deformed in alternate tension-compression at...of cycles in the transverse orientation of Ti-OAl-RE alloys deformed in alternate tension- A compression fatigue at 500 0C at a plastic strain

Method for compression of binary data

DOEpatents

Berlin, G.J.

1996-03-26

The disclosed method for compression of a series of data bytes, based on LZSS-based compression methods, provides faster decompression of the stored data. The method involves the creation of a flag bit buffer in a random access memory device for temporary storage of flag bits generated during normal LZSS-based compression. The flag bit buffer stores the flag bits separately from their corresponding pointers and uncompressed data bytes until all input data has been read. Then, the flag bits are appended to the compressed output stream of data. Decompression can be performed much faster because bit manipulation is only required when reading the flag bits and not when reading uncompressed data bytes and pointers. Uncompressed data is read using byte length instructions and pointers are read using word instructions, thus reducing the time required for decompression. 5 figs.

Perceptual Image Compression in Telemedicine

NASA Technical Reports Server (NTRS)

Watson, Andrew B.; Ahumada, Albert J., Jr.; Eckstein, Miguel; Null, Cynthia H. (Technical Monitor)

1996-01-01

The next era of space exploration, especially the "Mission to Planet Earth" will generate immense quantities of image data. For example, the Earth Observing System (EOS) is expected to generate in excess of one terabyte/day. NASA confronts a major technical challenge in managing this great flow of imagery: in collection, pre-processing, transmission to earth, archiving, and distribution to scientists at remote locations. Expected requirements in most of these areas clearly exceed current technology. Part of the solution to this problem lies in efficient image compression techniques. For much of this imagery, the ultimate consumer is the human eye. In this case image compression should be designed to match the visual capacities of the human observer. We have developed three techniques for optimizing image compression for the human viewer. The first consists of a formula, developed jointly with IBM and based on psychophysical measurements, that computes a DCT quantization matrix for any specified combination of viewing distance, display resolution, and display brightness. This DCT quantization matrix is used in most recent standards for digital image compression (JPEG, MPEG, CCITT H.261). The second technique optimizes the DCT quantization matrix for each individual image, based on the contents of the image. This is accomplished by means of a model of visual sensitivity to compression artifacts. The third technique extends the first two techniques to the realm of wavelet compression. Together these two techniques will allow systematic perceptual optimization of image compression in NASA imaging systems. Many of the image management challenges faced by NASA are mirrored in the field of telemedicine. Here too there are severe demands for transmission and archiving of large image databases, and the imagery is ultimately used primarily by human observers, such as radiologists. In this presentation I will describe some of our preliminary explorations of the applications of our technology to the special problems of telemedicine.

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

NASA Astrophysics Data System (ADS)

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.

HapZipper: sharing HapMap populations just got easier.

PubMed

Chanda, Pritam; Elhaik, Eran; Bader, Joel S

2012-11-01

The rapidly growing amount of genomic sequence data being generated and made publicly available necessitate the development of new data storage and archiving methods. The vast amount of data being shared and manipulated also create new challenges for network resources. Thus, developing advanced data compression techniques is becoming an integral part of data production and analysis. The HapMap project is one of the largest public resources of human single-nucleotide polymorphisms (SNPs), characterizing over 3 million SNPs genotyped in over 1000 individuals. The standard format and biological properties of HapMap data suggest that a dedicated genetic compression method can outperform generic compression tools. We propose a compression methodology for genetic data by introducing HapZipper, a lossless compression tool tailored to compress HapMap data beyond benchmarks defined by generic tools such as gzip, bzip2 and lzma. We demonstrate the usefulness of HapZipper by compressing HapMap 3 populations to <5% of their original sizes. HapZipper is freely downloadable from https://bitbucket.org/pchanda/hapzipper/downloads/HapZipper.tar.bz2.

Bit-Grooming: Shave Your Bits with Razor-sharp Precision

NASA Astrophysics Data System (ADS)

Zender, C. S.; Silver, J.

2017-12-01

Lossless compression can reduce climate data storage by 30-40%. Further reduction requires lossy compression that also reduces precision. Fortunately, geoscientific models and measurements generate false precision (scientifically meaningless data bits) that can be eliminated without sacrificing scientifically meaningful data. We introduce Bit Grooming, a lossy compression algorithm that removes the bloat due to false-precision, those bits and bytes beyond the meaningful precision of the data.Bit Grooming is statistically unbiased, applies to all floating point numbers, and is easy to use. Bit-Grooming reduces geoscience data storage requirements by 40-80%. We compared Bit Grooming to competitors Linear Packing, Layer Packing, and GRIB2/JPEG2000. The other compression methods have the edge in terms of compression, but Bit Grooming is the most accurate and certainly the most usable and portable.Bit Grooming provides flexible and well-balanced solutions to the trade-offs among compression, accuracy, and usability required by lossy compression. Geoscientists could reduce their long term storage costs, and show leadership in the elimination of false precision, by adopting Bit Grooming.

A material-sparing method for assessment of powder deformation characteristics using data collected during a single compression-decompression cycle.

PubMed

Katz, Jeffrey M; Roopwani, Rahul; Buckner, Ira S

2013-10-01

Compressibility profiles, or functions of solid fraction versus applied pressure, are used to provide insight into the fundamental mechanical behavior of powders during compaction. These functions, collected during compression (in-die) or post ejection (out-of-die), indicate the amount of pressure that a given powder formulation requires to be compressed to a given density or thickness. To take advantage of the benefits offered by both methods, the data collected in-die during a single compression-decompression cycle will be used to generate the equivalent of a complete out-of-die compressibility profile that has been corrected for both elastic and viscoelastic recovery of the powder. This method has been found to be both a precise and accurate means of evaluating out-of-die compressibility for four common tableting excipients. Using this method, a comprehensive characterization of powder compaction behavior, specifically in relation to plastic/brittle, elastic and viscoelastic deformation, can be obtained. Not only is the method computationally simple, but it is also material-sparing. The ability to characterize powder compressibility using this approach can improve productivity and streamline tablet development studies. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

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

Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.

Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearlymore » establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. As a result, this nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.« less

Clinical assessment of heart chamber size and valve motion during cardiopulmonary resuscitation by two-dimensional echocardiography.

PubMed

Rich, S; Wix, H L; Shapiro, E P

1981-09-01

It has been generally accepted that enhanced blood flow during closed-chest CPR is generated from compression of the heart between the sternum and the spine. To visualize the heart during closed-chest massage, we performed two-dimensional echocardiography (2DE) during resuscitation efforts in four patients who had cardiac arrest. 2DE analysis showed that (1) the LV internal dimensions did not change appreciably with chest compression; (2) the mitral and aortic valves were open simultaneously during the compression phase; (3) blood flow into the right heart, as evidenced by saline bubble contrast, occurred during the relaxation phase; and (4) compression of the right ventricle and LA occurred in varying amounts in all patients. We conclude that stroke volume from the heart during CPR does not result from compression of the LV. Rather, CPR-induced improved cardiocirculatory dynamics appear to be principally the result of changes in intrathoracic pressure created by sternal compression.

Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

DOE PAGES

Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; ...

2017-03-16

Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearlymore » establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. As a result, this nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.« less

Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

NASA Astrophysics Data System (ADS)

Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

2017-03-01

Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.

An Implementation Of Elias Delta Code And ElGamal Algorithm In Image Compression And Security

NASA Astrophysics Data System (ADS)

Rachmawati, Dian; Andri Budiman, Mohammad; Saffiera, Cut Amalia

2018-01-01

In data transmission such as transferring an image, confidentiality, integrity, and efficiency of data storage aspects are highly needed. To maintain the confidentiality and integrity of data, one of the techniques used is ElGamal. The strength of this algorithm is found on the difficulty of calculating discrete logs in a large prime modulus. ElGamal belongs to the class of Asymmetric Key Algorithm and resulted in enlargement of the file size, therefore data compression is required. Elias Delta Code is one of the compression algorithms that use delta code table. The image was first compressed using Elias Delta Code Algorithm, then the result of the compression was encrypted by using ElGamal algorithm. Prime test was implemented using Agrawal Biswas Algorithm. The result showed that ElGamal method could maintain the confidentiality and integrity of data with MSE and PSNR values 0 and infinity. The Elias Delta Code method generated compression ratio and space-saving each with average values of 62.49%, and 37.51%.

Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power.

PubMed

Li, Binsong; Bian, Kaifu; Lane, J Matthew D; Salerno, K Michael; Grest, Gary S; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

2017-03-16

Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.

Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

PubMed Central

Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

2017-01-01

Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales. PMID:28300067

Pseudoelastic intramedullary nailing for tibio-talo-calcaneal arthrodesis.

PubMed

Yakacki, Christopher M; Gall, Ken; Dirschl, Douglas R; Pacaccio, Douglas J

2011-03-01

Tibio-talo-calcaneal (TTC) arthrodesis is a procedure to treat severe ankle arthropathy by providing a pain-free and stable fusion. Intramedullary (IM) nails offer a method of internal fixation for TTC arthrodesis by providing compressive stability, as well as shear and torsional rigidity. IM nails have been developed to apply compression to the TTC complex during installation; however, current designs are highly susceptible to a loss of compression when exposed to small amounts of bone resorption and cyclic loading. Nickel titanium (NiTi) is a shape-memory alloy capable of recovering large amounts of deformation via shape-memory or pseudoelasticity. Currently, the next generation of IM nails is being developed to utilize the adaptive, pseudoelastic properties of NiTi and provide a fusion nail that is resistant to loss of compression or loosening. Specifically, the pseudoelastic IM nail contains an internal NiTi compression element that applies sustained compression during the course of fusion, analogous to external fixators. © 2011 Expert Reviews Ltd

An efficient coding algorithm for the compression of ECG signals using the wavelet transform.

PubMed

Rajoub, Bashar A

2002-04-01

A wavelet-based electrocardiogram (ECG) data compression algorithm is proposed in this paper. The ECG signal is first preprocessed, the discrete wavelet transform (DWT) is then applied to the preprocessed signal. Preprocessing guarantees that the magnitudes of the wavelet coefficients be less than one, and reduces the reconstruction errors near both ends of the compressed signal. The DWT coefficients are divided into three groups, each group is thresholded using a threshold based on a desired energy packing efficiency. A binary significance map is then generated by scanning the wavelet decomposition coefficients and outputting a binary one if the scanned coefficient is significant, and a binary zero if it is insignificant. Compression is achieved by 1) using a variable length code based on run length encoding to compress the significance map and 2) using direct binary representation for representing the significant coefficients. The ability of the coding algorithm to compress ECG signals is investigated, the results were obtained by compressing and decompressing the test signals. The proposed algorithm is compared with direct-based and wavelet-based compression algorithms and showed superior performance. A compression ratio of 24:1 was achieved for MIT-BIH record 117 with a percent root mean square difference as low as 1.08%.

Characterization of particle deformation during compression measured by confocal laser scanning microscopy.

PubMed

Guo, H X; Heinämäki, J; Yliruusi, J

1999-09-20

Direct compression of riboflavin sodium phosphate tablets was studied by confocal laser scanning microscopy (CLSM). The technique is non-invasive and generates three-dimensional (3D) images. Tablets of 1% riboflavin sodium phosphate with two grades of microcrystalline cellulose (MCC) were individually compressed at compression forces of 1.0 and 26.8 kN. The behaviour and deformation of drug particles on the upper and lower surfaces of the tablets were studied under compression forces. Even at the lower compression force, distinct recrystallized areas in the riboflavin sodium phosphate particles were observed in both Avicel PH-101 and Avicel PH-102 tablets. At the higher compression force, the recrystallization of riboflavin sodium phosphate was more extensive on the upper surface of the Avicel PH-102 tablet than the Avicel PH-101 tablet. The plastic deformation properties of both MCC grades reduced the fragmentation of riboflavin sodium phosphate particles. When compressed with MCC, riboflavin sodium phosphate behaved as a plastic material. The riboflavin sodium phosphate particles were more tightly bound on the upper surface of the tablet than on the lower surface, and this could also be clearly distinguished by CLSM. Drug deformation could not be visualized by other techniques. Confocal laser scanning microscopy provides valuable information on the internal mechanisms of direct compression of tablets.

Pneumatic microfluidic cell compression device for high-throughput study of chondrocyte mechanobiology.

PubMed

Lee, Donghee; Erickson, Alek; You, Taesun; Dudley, Andrew T; Ryu, Sangjin

2018-06-13

Hyaline cartilage is a specialized type of connective tissue that lines many moveable joints (articular cartilage) and contributes to bone growth (growth plate cartilage). Hyaline cartilage is composed of a single cell type, the chondrocyte, which produces a unique hydrated matrix to resist compressive stress. Although compressive stress has profound effects on transcriptional networks and matrix biosynthesis in chondrocytes, mechanistic relationships between strain, signal transduction, cell metabolism, and matrix production remain superficial. Here, we describe development and validation of a polydimethylsiloxane (PDMS)-based pneumatic microfluidic cell compression device which generates multiple compression conditions in a single platform. The device contained an array of PDMS balloons of different sizes which were actuated by pressurized air, and the balloons compressed chondrocytes cells in alginate hydrogel constructs. Our characterization and testing of the device showed that the developed platform could compress chondrocytes with various magnitudes simultaneously with negligible effect on cell viability. Also, the device is compatible with live cell imaging to probe early effects of compressive stress, and it can be rapidly dismantled to facilitate molecular studies of compressive stress on transcriptional networks. Therefore, the proposed device will enhance the productivity of chondrocyte mechanobiology studies, and it can be applied to study mechanobiology of other cell types.

GTZ: a fast compression and cloud transmission tool optimized for FASTQ files.

PubMed

Xing, Yuting; Li, Gen; Wang, Zhenguo; Feng, Bolun; Song, Zhuo; Wu, Chengkun

2017-12-28

The dramatic development of DNA sequencing technology is generating real big data, craving for more storage and bandwidth. To speed up data sharing and bring data to computing resource faster and cheaper, it is necessary to develop a compression tool than can support efficient compression and transmission of sequencing data onto the cloud storage. This paper presents GTZ, a compression and transmission tool, optimized for FASTQ files. As a reference-free lossless FASTQ compressor, GTZ treats different lines of FASTQ separately, utilizes adaptive context modelling to estimate their characteristic probabilities, and compresses data blocks with arithmetic coding. GTZ can also be used to compress multiple files or directories at once. Furthermore, as a tool to be used in the cloud computing era, it is capable of saving compressed data locally or transmitting data directly into cloud by choice. We evaluated the performance of GTZ on some diverse FASTQ benchmarks. Results show that in most cases, it outperforms many other tools in terms of the compression ratio, speed and stability. GTZ is a tool that enables efficient lossless FASTQ data compression and simultaneous data transmission onto to cloud. It emerges as a useful tool for NGS data storage and transmission in the cloud environment. GTZ is freely available online at: https://github.com/Genetalks/gtz .

Performance of a Space-Based Wavelet Compressor for Plasma Count Data on the MMS Fast Plasma Investigation

NASA Technical Reports Server (NTRS)

Barrie, A. C.; Smith, S. E.; Dorelli, J. C.; Gershman, D. J.; Yeh, P.; Schiff, C.; Avanov, L. A.

2017-01-01

Data compression has been a staple of imaging instruments for years. Recently, plasma measurements have utilized compression with relatively low compression ratios. The Fast Plasma Investigation (FPI) on board the Magnetospheric Multiscale (MMS) mission generates data roughly 100 times faster than previous plasma instruments, requiring a higher compression ratio to fit within the telemetry allocation. This study investigates the performance of a space-based compression standard employing a Discrete Wavelet Transform and a Bit Plane Encoder (DWT/BPE) in compressing FPI plasma count data. Data from the first 6 months of FPI operation are analyzed to explore the error modes evident in the data and how to adapt to them. While approximately half of the Dual Electron Spectrometer (DES) maps had some level of loss, it was found that there is little effect on the plasma moments and that errors present in individual sky maps are typically minor. The majority of Dual Ion Spectrometer burst sky maps compressed in a lossless fashion, with no error introduced during compression. Because of induced compression error, the size limit for DES burst images has been increased for Phase 1B. Additionally, it was found that the floating point compression mode yielded better results when images have significant compression error, leading to floating point mode being used for the fast survey mode of operation for Phase 1B. Despite the suggested tweaks, it was found that wavelet-based compression, and a DWT/BPE algorithm in particular, is highly suitable to data compression for plasma measurement instruments and can be recommended for future missions.

Slow Dynamics Model of Compressed Air Energy Storage and Battery Storage Technologies for Automatic Generation Control

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

Krishnan, Venkat; Das, Trishna

Increasing variable generation penetration and the consequent increase in short-term variability makes energy storage technologies look attractive, especially in the ancillary market for providing frequency regulation services. This paper presents slow dynamics model for compressed air energy storage and battery storage technologies that can be used in automatic generation control studies to assess the system frequency response and quantify the benefits from storage technologies in providing regulation service. The paper also represents the slow dynamics model of the power system integrated with storage technologies in a complete state space form. The storage technologies have been integrated to the IEEE 24more » bus system with single area, and a comparative study of various solution strategies including transmission enhancement and combustion turbine have been performed in terms of generation cycling and frequency response performance metrics.« less

The Role of Arch Compression and Metatarsophalangeal Joint Dynamics in Modulating Plantar Fascia Strain in Running

PubMed Central

McDonald, Kirsty A.; Stearne, Sarah M.; Alderson, Jacqueline A.; North, Ian; Pires, Neville J.; Rubenson, Jonas

2016-01-01

Elastic energy returned from passive-elastic structures of the lower limb is fundamental in lowering the mechanical demand on muscles during running. The purpose of this study was to investigate the two length-modulating mechanisms of the plantar fascia, namely medial longitudinal arch compression and metatarsophalangeal joint (MPJ) excursion, and to determine how these mechanisms modulate strain, and thus elastic energy storage/return of the plantar fascia during running. Eighteen runners (9 forefoot and 9 rearfoot strike) performed three treadmill running trials; unrestricted shod, shod with restricted arch compression (via an orthotic-style insert), and barefoot. Three-dimensional motion capture and ground reaction force data were used to calculate lower limb kinematics and kinetics including MPJ angles, moments, powers and work. Estimates of plantar fascia strain due to arch compression and MPJ excursion were derived using a geometric model of the arch and a subject-specific musculoskeletal model of the plantar fascia, respectively. The plantar fascia exhibited a typical elastic stretch-shortening cycle with the majority of strain generated via arch compression. This strategy was similar in fore- and rear-foot strike runners. Restricting arch compression, and hence the elastic-spring function of the arch, was not compensated for by an increase in MPJ-derived strain. In the second half of stance the plantar fascia was found to transfer energy between the MPJ (energy absorption) and the arch (energy production during recoil). This previously unreported energy transfer mechanism reduces the strain required by the plantar fascia in generating useful positive mechanical work at the arch during running. PMID:27054319

The Role of Arch Compression and Metatarsophalangeal Joint Dynamics in Modulating Plantar Fascia Strain in Running.

PubMed

McDonald, Kirsty A; Stearne, Sarah M; Alderson, Jacqueline A; North, Ian; Pires, Neville J; Rubenson, Jonas

2016-01-01

Elastic energy returned from passive-elastic structures of the lower limb is fundamental in lowering the mechanical demand on muscles during running. The purpose of this study was to investigate the two length-modulating mechanisms of the plantar fascia, namely medial longitudinal arch compression and metatarsophalangeal joint (MPJ) excursion, and to determine how these mechanisms modulate strain, and thus elastic energy storage/return of the plantar fascia during running. Eighteen runners (9 forefoot and 9 rearfoot strike) performed three treadmill running trials; unrestricted shod, shod with restricted arch compression (via an orthotic-style insert), and barefoot. Three-dimensional motion capture and ground reaction force data were used to calculate lower limb kinematics and kinetics including MPJ angles, moments, powers and work. Estimates of plantar fascia strain due to arch compression and MPJ excursion were derived using a geometric model of the arch and a subject-specific musculoskeletal model of the plantar fascia, respectively. The plantar fascia exhibited a typical elastic stretch-shortening cycle with the majority of strain generated via arch compression. This strategy was similar in fore- and rear-foot strike runners. Restricting arch compression, and hence the elastic-spring function of the arch, was not compensated for by an increase in MPJ-derived strain. In the second half of stance the plantar fascia was found to transfer energy between the MPJ (energy absorption) and the arch (energy production during recoil). This previously unreported energy transfer mechanism reduces the strain required by the plantar fascia in generating useful positive mechanical work at the arch during running.

ERGC: an efficient referential genome compression algorithm

PubMed Central

Saha, Subrata; Rajasekaran, Sanguthevar

2015-01-01

Motivation: Genome sequencing has become faster and more affordable. Consequently, the number of available complete genomic sequences is increasing rapidly. As a result, the cost to store, process, analyze and transmit the data is becoming a bottleneck for research and future medical applications. So, the need for devising efficient data compression and data reduction techniques for biological sequencing data is growing by the day. Although there exists a number of standard data compression algorithms, they are not efficient in compressing biological data. These generic algorithms do not exploit some inherent properties of the sequencing data while compressing. To exploit statistical and information-theoretic properties of genomic sequences, we need specialized compression algorithms. Five different next-generation sequencing data compression problems have been identified and studied in the literature. We propose a novel algorithm for one of these problems known as reference-based genome compression. Results: We have done extensive experiments using five real sequencing datasets. The results on real genomes show that our proposed algorithm is indeed competitive and performs better than the best known algorithms for this problem. It achieves compression ratios that are better than those of the currently best performing algorithms. The time to compress and decompress the whole genome is also very promising. Availability and implementation: The implementations are freely available for non-commercial purposes. They can be downloaded from http://engr.uconn.edu/∼rajasek/ERGC.zip. Contact: rajasek@engr.uconn.edu PMID:26139636

Apparatus for measuring tensile and compressive properties of solid materials at cryogenic temperatures

DOEpatents

Gonczy, J.D.; Markley, F.W.; McCaw, W.R.; Niemann, R.C.

1992-04-21

An apparatus for evaluating the tensile and compressive properties of material samples at very low or cryogenic temperatures employs a stationary frame and a dewar mounted below the frame. A pair of coaxial cylindrical tubes extend downward towards the bottom of the dewar. A compressive or tensile load is generated hydraulically and is transmitted by the inner tube to the material sample. The material sample is located near the bottom of the dewar in a liquid refrigerant bath. The apparatus employs a displacement measuring device, such as a linear variable differential transformer, to measure the deformation of the material sample relative to the amount of compressive or tensile force applied to the sample. 7 figs.

The FBI compression standard for digitized fingerprint images

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

Brislawn, C.M.; Bradley, J.N.; Onyshczak, R.J.

1996-10-01

The FBI has formulated national standards for digitization and compression of gray-scale fingerprint images. The compression algorithm for the digitized images is based on adaptive uniform scalar quantization of a discrete wavelet transform subband decomposition, a technique referred to as the wavelet/scalar quantization method. The algorithm produces archival-quality images at compression ratios of around 15 to 1 and will allow the current database of paper fingerprint cards to be replaced by digital imagery. A compliance testing program is also being implemented to ensure high standards of image quality and interchangeability of data between different implementations. We will review the currentmore » status of the FBI standard, including the compliance testing process and the details of the first-generation encoder.« less

FBI compression standard for digitized fingerprint images

NASA Astrophysics Data System (ADS)

Brislawn, Christopher M.; Bradley, Jonathan N.; Onyshczak, Remigius J.; Hopper, Thomas

1996-11-01

The FBI has formulated national standards for digitization and compression of gray-scale fingerprint images. The compression algorithm for the digitized images is based on adaptive uniform scalar quantization of a discrete wavelet transform subband decomposition, a technique referred to as the wavelet/scalar quantization method. The algorithm produces archival-quality images at compression ratios of around 15 to 1 and will allow the current database of paper fingerprint cards to be replaced by digital imagery. A compliance testing program is also being implemented to ensure high standards of image quality and interchangeability of data between different implementations. We will review the current status of the FBI standard, including the compliance testing process and the details of the first-generation encoder.

The Origin of Compressible Magnetic Turbulence in the Very Local Interstellar Medium

NASA Astrophysics Data System (ADS)

Zank, G. P.; Du, S.; Hunana, P.

2017-06-01

Voyager 1 observed compressible magnetic turbulence in the very local interstellar medium (VLISM). We show that inner heliosheath (IHS) fast- and slow-mode waves incident on the heliopause (HP) generate VLISM fast-mode waves only that propagate into the VLISM. We suggest that this is the origin of compressible turbulence in the VLISM. We show that fast- and slow-mode waves transmitted across a tangential discontinuity such as the HP are strongly refracted on crossing the HP and subsequently propagate at highly oblique angles to the VLISM magnetic field. Thus, fast-mode waves in the VLISM contribute primarily to the compressible and not the transverse components of the VLISM fluctuating magnetic field variance < δ {\\hat{B}}2> since < δ {\\hat{B}}{fz}2> \

Dynamic compression of copper to over 450 GPa: A high-pressure standard

DOE PAGES

Kraus, R. G.; Davis, J. -P.; Seagle, C. T.; ...

2016-04-12

We obtained an absolute stress-density path for shocklessly compressed copper to over 450 GPa. A magnetic pressure drive is temporally tailored to generate shockless compression waves through over 2.5-mm-thick copper samples. Furthermore, the free-surface velocity data is analyzed for Lagrangian sound velocity using the iterative Lagrangian analysis (ILA) technique, which relies upon the method of characteristics. We correct for the effects of strength and plastic work heating to determine an isentropic compression path. By assuming a Debye model for the heat capacity, we can further correct the isentrope to an isotherm. Finally, our determination of the isentrope and isotherm ofmore » copper represents a highly accurate pressure standard for copper to over 450 GPa.« less

Real-time and encryption efficiency improvements of simultaneous fusion, compression and encryption method based on chaotic generators

NASA Astrophysics Data System (ADS)

Jridi, Maher; Alfalou, Ayman

2018-03-01

In this paper, enhancement of an existing optical simultaneous fusion, compression and encryption (SFCE) scheme in terms of real-time requirements, bandwidth occupation and encryption robustness is proposed. We have used and approximate form of the DCT to decrease the computational resources. Then, a novel chaos-based encryption algorithm is introduced in order to achieve the confusion and diffusion effects. In the confusion phase, Henon map is used for row and column permutations, where the initial condition is related to the original image. Furthermore, the Skew Tent map is employed to generate another random matrix in order to carry out pixel scrambling. Finally, an adaptation of a classical diffusion process scheme is employed to strengthen security of the cryptosystem against statistical, differential, and chosen plaintext attacks. Analyses of key space, histogram, adjacent pixel correlation, sensitivity, and encryption speed of the encryption scheme are provided, and favorably compared to those of the existing crypto-compression system. The proposed method has been found to be digital/optical implementation-friendly which facilitates the integration of the crypto-compression system on a very broad range of scenarios.

Ramp compression of a metallic liner driven by a shaped 5 MA current on the SPHINX machine

NASA Astrophysics Data System (ADS)

D'Almeida, Thierry; Lassalle, Francis; Morell, Alain; Grunenwald, Julien; Zucchini, Frédéric; Loyen, Arnaud; Maysonnave, Thomas; Chuvatin, Alexandre

2013-06-01

SPHINX is a 6MA, 1- μs Linear Transformer Driver operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being considered for improving the generator performances, there is a compact Dynamic Load Current Amplifier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse. We present the overall experimental configuration chosen for these experiments, based on electrical and hydrodynamic simulations. Initial results obtained over a set of experiments on an aluminum cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented. Details of the electrical and Photonic Doppler Velocimetry (PDV) setups used to monitor and diagnose the ramp compression experiments are provided. Current profiles measured at various locations across the system, particularly the load current, agree with simulated current profile and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements agree with the hydrocode results obtained using the measured load current as the input. Higher ramp pressure levels are foreseen in future experiments with an improved DLCM system.

Power-to-heat in adiabatic compressed air energy storage power plants for cost reduction and increased flexibility

NASA Astrophysics Data System (ADS)

Dreißigacker, Volker

2018-04-01

The development of new technologies for large-scale electricity storage is a key element in future flexible electricity transmission systems. Electricity storage in adiabatic compressed air energy storage (A-CAES) power plants offers the prospect of making a substantial contribution to reach this goal. This concept allows efficient, local zero-emission electricity storage on the basis of compressed air in underground caverns. The compression and expansion of air in turbomachinery help to balance power generation peaks that are not demand-driven on the one hand and consumption-induced load peaks on the other. For further improvements in cost efficiencies and flexibility, system modifications are necessary. Therefore, a novel concept regarding the integration of an electrical heating component is investigated. This modification allows increased power plant flexibilities and decreasing component sizes due to the generated high temperature heat with simultaneously decreasing total round trip efficiencies. For an exemplarily A-CAES case simulation studies regarding the electrical heating power and thermal energy storage sizes were conducted to identify the potentials in cost reduction of the central power plant components and the loss in round trip efficiency.

Characterization of short-pulse laser-produced x-rays for diagnosing magnetically driven cylindrical isentropic compression

NASA Astrophysics Data System (ADS)

Sawada, Hiroshi; Daykin, Tyler; Bauer, Bruno; Beg, Farhat

2017-10-01

We have developed an experimental platform to study material properties of magnetically compressed cylinder using a 1 MA pulsed power generator Zebra and a 50 TW subpicosecond short-pulse laser Leopard at the UNR's Nevada Terawatt Facility. According to a MHD simulation, strong magnetic fields generated by 100 ns rise time Zebra current can quasi-isentropically compress a material to the strongly coupled plasma regime. Taking advantage of the cylindrical geometry, a metal rod can be brought to higher pressures than that in the planar geometry. To diagnose the compressed rod with high precision x-ray measurements, an initial laser-only experiment was carried out to characterize laser-produced x-rays. Interaction of a high-intensity, short-pulse laser with solids produces broadband and monochromatic x-rays with photon energies high enough to probe dense metal rods. Bremsstrahlung was measured with Imaging plate-based filter stack spectrometers and monochromatic 8.0 keV Cu K-alpha was recorded with an absolutely calibrated Bragg crystal spectrometer. The broadband x-ray source was applied to radiography of thick metal objects and different filter materials were tested. The experimental results and a design of a coupled experiment will be presented.

Experimental research of the influence of the strength of ore samples on the parameters of an electromagnetic signal during acoustic excitation in the process of uniaxial compression

NASA Astrophysics Data System (ADS)

Yavorovich, L. V.; Bespal`ko, A. A.; Fedotov, P. I.

2018-01-01

Parameters of electromagnetic responses (EMRe) generated during uniaxial compression of rock samples under excitation by deterministic acoustic pulses are presented and discussed. Such physical modeling in the laboratory allows to reveal the main regularities of electromagnetic signals (EMS) generation in rock massive. The influence of the samples mechanical properties on the parameters of the EMRe excited by an acoustic signal in the process of uniaxial compression is considered. It has been established that sulfides and quartz in the rocks of the Tashtagol iron ore deposit (Western Siberia, Russia) contribute to the conversion of mechanical energy into the energy of the electromagnetic field, which is expressed in an increase in the EMS amplitude. The decrease in the EMS amplitude when the stress-strain state of the sample changes during the uniaxial compression is observed when the amount of conductive magnetite contained in the rock is increased. The obtained results are important for the physical substantiation of testing methods and monitoring of changes in the stress-strain state of the rock massive by the parameters of electromagnetic signals and the characteristics of electromagnetic emission.

Isolated few-cycle radiation from chirped-pulse compression of a superradiant free-electron laser

DOE PAGES

Huang, Yen -Chieh; Zhang, Zhen; Chen, Chia -Hsiang; ...

2015-08-31

When a short electron bunch traverses an undulator to radiate a wavelength longer than the bunch length, intense superradiance from the electron bunch can quickly deplete the electron’s kinetic energy and lead to generation of an isolated chirped radiation pulse. Here, we develop a theory to describe this novel chirped pulse radiation in a superradiant free-electron laser and show the opportunity to generate isolated few-cycle high-power radiation through chirped-pulse compression after the undulator. The theory is completely characterized by how fast the electron energy is depleted for a given length of an undulator. We further present two design examples atmore » the THz and extreme-ultraviolet wavelengths and numerically generate isolated three- and nine-cycle radiation pulses, respectively.« less

Compression of head-related transfer function using autoregressive-moving-average models and Legendre polynomials.

PubMed

Shekarchi, Sayedali; Hallam, John; Christensen-Dalsgaard, Jakob

2013-11-01

Head-related transfer functions (HRTFs) are generally large datasets, which can be an important constraint for embedded real-time applications. A method is proposed here to reduce redundancy and compress the datasets. In this method, HRTFs are first compressed by conversion into autoregressive-moving-average (ARMA) filters whose coefficients are calculated using Prony's method. Such filters are specified by a few coefficients which can generate the full head-related impulse responses (HRIRs). Next, Legendre polynomials (LPs) are used to compress the ARMA filter coefficients. LPs are derived on the sphere and form an orthonormal basis set for spherical functions. Higher-order LPs capture increasingly fine spatial details. The number of LPs needed to represent an HRTF, therefore, is indicative of its spatial complexity. The results indicate that compression ratios can exceed 98% while maintaining a spectral error of less than 4 dB in the recovered HRTFs.

Use of circulating-fluidized-bed combustors in compressed-air energy storage systems

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

Nakhamkin, M.; Patel, M.

1990-07-01

This report presents the result of a study conducted by Energy Storage and Power Consultants (ESPC), with the objective to develop and analyze compressed air energy storage (CAES) power plant concepts which utilize coal-fired circulating fluidized bed combustors (CFBC) for heating air during generating periods. The use of a coal-fired CFBC unit for indirect heating of the compressed air, in lieu of the current turbomachinery combustors, would eliminate the need for expensive premium fuels by a CAES facility. The CAES plant generation heat rate is approximately one-half of that for a conventional steam condensing power plant. Therefore, the required CFBCmore » heat generation capacity and capital costs would be lower per kW of power generation capacity. Three CAES/CFBC concepts were identified as the most promising, and were optimized using specifically developed computerized procedures. These concepts utilize various configurations of reheat turbomachinery trains specifically developed for CAES application as parts of the integrated CAES/CFBC plant concepts. The project team concluded that the optimized CAES/CFBC integrated plant concepts present a potentially attractive alternative to conventional steam generation power plants using CFBC or pulverized coal-fired boilers. A comparison of the results from the economic analysis performed on three concepts suggests that one of them (Concept 3) is the preferred concept. This concept has a two shaft turbomachinery train arrangement, and provides for load management functions by the compressor-electric motor train, and continuous base load operation of the turboexpander-electric generator train and the CFBC unit. 6 refs., 30 figs., 14 tabs.« less

Light-weight reference-based compression of FASTQ data.

PubMed

Zhang, Yongpeng; Li, Linsen; Yang, Yanli; Yang, Xiao; He, Shan; Zhu, Zexuan

2015-06-09

The exponential growth of next generation sequencing (NGS) data has posed big challenges to data storage, management and archive. Data compression is one of the effective solutions, where reference-based compression strategies can typically achieve superior compression ratios compared to the ones not relying on any reference. This paper presents a lossless light-weight reference-based compression algorithm namely LW-FQZip to compress FASTQ data. The three components of any given input, i.e., metadata, short reads and quality score strings, are first parsed into three data streams in which the redundancy information are identified and eliminated independently. Particularly, well-designed incremental and run-length-limited encoding schemes are utilized to compress the metadata and quality score streams, respectively. To handle the short reads, LW-FQZip uses a novel light-weight mapping model to fast map them against external reference sequence(s) and produce concise alignment results for storage. The three processed data streams are then packed together with some general purpose compression algorithms like LZMA. LW-FQZip was evaluated on eight real-world NGS data sets and achieved compression ratios in the range of 0.111-0.201. This is comparable or superior to other state-of-the-art lossless NGS data compression algorithms. LW-FQZip is a program that enables efficient lossless FASTQ data compression. It contributes to the state of art applications for NGS data storage and transmission. LW-FQZip is freely available online at: http://csse.szu.edu.cn/staff/zhuzx/LWFQZip.

pyPcazip: A PCA-based toolkit for compression and analysis of molecular simulation data

NASA Astrophysics Data System (ADS)

Shkurti, Ardita; Goni, Ramon; Andrio, Pau; Breitmoser, Elena; Bethune, Iain; Orozco, Modesto; Laughton, Charles A.

The biomolecular simulation community is currently in need of novel and optimised software tools that can analyse and process, in reasonable timescales, the large generated amounts of molecular simulation data. In light of this, we have developed and present here pyPcazip: a suite of software tools for compression and analysis of molecular dynamics (MD) simulation data. The software is compatible with trajectory file formats generated by most contemporary MD engines such as AMBER, CHARMM, GROMACS and NAMD, and is MPI parallelised to permit the efficient processing of very large datasets. pyPcazip is a Unix based open-source software (BSD licenced) written in Python.

Application of nonlinear pulse shaping of femtosecond pulse generation in a fiber amplifier at 500 MHz repetition rate

NASA Astrophysics Data System (ADS)

Liu, Yang; Luo, Daping; Wang, Chao; Zhu, Zhiwei; Li, Wenxue

2018-03-01

We numerically and experimentally demonstrate that a nonlinear pulse shaping technique based on pre-chirping management in a short gain fiber can be exploited to improve the quality of a compressed pulse. With prior tuning of the pulse chirp, the amplified pulse express different nonlinear propagating processes. A spectrum with s flat top and more smooth wings, showing a similariton feature, generates with the optimal initial pulse chirp, and the shortest pulses with minimal pulse pedestals are obtained. Experimental results show the ability of nonlinear pulse shaping to enhance the quality of compressed pulses, as theoretically expected.

Quasi-isentropic compression of materials using the magnetic loading technique

NASA Astrophysics Data System (ADS)

Ao, Tommy

2009-06-01

The Isentropic Compression Experiment (ICE) technique has proven to be a valuable complement to the well-established method of shock compression of condensed matter. The magnetic loading technique using pulsed power generators was first developed about a decade ago on the Z Accelerator, and has matured significantly. The recent development of small pulsed power generators have enabled several key issues in ICE, such as panel & sample preparation, uniformity of loading, and edge effects to be studied. Veloce is a medium-voltage, high-current, compact pulsed power generator developed for cost effective isentropic experiments. The machine delivers up to 3 MA of current rapidly (˜ 440-530 ns) into an inductive load where significant magnetic pressures are produced. Examples of recent material strength measurements from quasi-isentropic loading and unloading of materials will be presented. In particular, the influence that the strength of interferometer windows has on wave profile analyses and thus the inferred strength of materials is examined. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

The CCSDS Lossless Data Compression Algorithm for Space Applications

NASA Technical Reports Server (NTRS)

Yeh, Pen-Shu; Day, John H. (Technical Monitor)

2001-01-01

In the late 80's, when the author started working at the Goddard Space Flight Center (GSFC) for the National Aeronautics and Space Administration (NASA), several scientists there were in the process of formulating the next generation of Earth viewing science instruments, the Moderate Resolution Imaging Spectroradiometer (MODIS). The instrument would have over thirty spectral bands and would transmit enormous data through the communications channel. This was when the author was assigned the task of investigating lossless compression algorithms for space implementation to compress science data in order to reduce the requirement on bandwidth and storage.

An iterative forward analysis technique to determine the equation of state of dynamically compressed materials

DOE PAGES

Ali, S. J.; Kraus, R. G.; Fratanduono, D. E.; ...

2017-05-18

Here, we developed an iterative forward analysis (IFA) technique with the ability to use hydrocode simulations as a fitting function for analysis of dynamic compression experiments. The IFA method optimizes over parameterized quantities in the hydrocode simulations, breaking the degeneracy of contributions to the measured material response. Velocity profiles from synthetic data generated using a hydrocode simulation are analyzed as a first-order validation of the technique. We also analyze multiple magnetically driven ramp compression experiments on copper and compare with more conventional techniques. Excellent agreement is obtained in both cases.

Vortex Generators in a Two-Dimensional, External-Compression Supersonic Inlet

NASA Technical Reports Server (NTRS)

Baydar, Ezgihan; Lu, Frank K.; Slater, John W.

2016-01-01

Computational fluid dynamics simulations are performed as part of a process to design a vortex generator array for a two-dimensional inlet for Mach 1.6. The objective is to improve total pressure recovery a on at the engine face of the inlet. Both vane-type and ramp-type vortex generators are examined.

3D Compressible Melt Transport with Adaptive Mesh Refinement

NASA Astrophysics Data System (ADS)

Dannberg, Juliane; Heister, Timo

2015-04-01

Melt generation and migration have been the subject of numerous investigations, but their typical time and length-scales are vastly different from mantle convection, which makes it difficult to study these processes in a unified framework. The equations that describe coupled Stokes-Darcy flow have been derived a long time ago and they have been successfully implemented and applied in numerical models (Keller et al., 2013). However, modelling magma dynamics poses the challenge of highly non-linear and spatially variable material properties, in particular the viscosity. Applying adaptive mesh refinement to this type of problems is particularly advantageous, as the resolution can be increased in mesh cells where melt is present and viscosity gradients are high, whereas a lower resolution is sufficient in regions without melt. In addition, previous models neglect the compressibility of both the solid and the fluid phase. However, experiments have shown that the melt density change from the depth of melt generation to the surface leads to a volume increase of up to 20%. Considering these volume changes in both phases also ensures self-consistency of models that strive to link melt generation to processes in the deeper mantle, where the compressibility of the solid phase becomes more important. We describe our extension of the finite-element mantle convection code ASPECT (Kronbichler et al., 2012) that allows for solving additional equations describing the behaviour of silicate melt percolating through and interacting with a viscously deforming host rock. We use the original compressible formulation of the McKenzie equations, augmented by an equation for the conservation of energy. This approach includes both melt migration and melt generation with the accompanying latent heat effects. We evaluate the functionality and potential of this method using a series of simple model setups and benchmarks, comparing results of the compressible and incompressible formulation and showing the potential of adaptive mesh refinement when applied to melt migration. Our model of magma dynamics provides a framework for modelling processes on different scales and investigating links between processes occurring in the deep mantle and melt generation and migration. This approach could prove particularly useful applied to modelling the generation of komatiites or other melts originating in greater depths. Keller, T., D. A. May, and B. J. P. Kaus (2013), Numerical modelling of magma dynamics coupled to tectonic deformation of lithosphere and crust, Geophysical Journal International, 195 (3), 1406-1442. Kronbichler, M., T. Heister, and W. Bangerth (2012), High accuracy mantle convection simulation through modern numerical methods, Geophysical Journal International, 191 (1), 12-29.

Electron beam generation in the turbulent plasma of Z-pinch discharges

NASA Astrophysics Data System (ADS)

Vikhrev, Victor V.; Baronova, Elena O.

1997-05-01

Numerical modeling of the process of electron beam generation in z-pinch discharges are presented. The proposed model represents the electron beam generation under turbulent plasma conditions. Strong current distribution inhomogeneity in the plasma column has been accounted for the adequate generation process investigation. Electron beam is generated near the maximum of compression due to run away mechanism and it is not related with the current break effect.

Computational Simulation of Explosively Generated Pulsed Power Devices

DTIC Science & Technology

2013-03-21

to practical applications. These are the magnetic flux compression generators (FCG), ferromagnetic generators (FMG) and ferroelectric generators (FEG...The first device works on the concept of field interaction between a conducting medium and a magnetic field. The last two devices make use of either... magnetic or electric fields stored in a prepared material (4). This research will focus on the ferroelectric generator as a high voltage source for

A Unified Steganalysis Framework

DTIC Science & Technology

2013-04-01

contains more than 1800 images of different scenes. In the experiments, we used four JPEG based steganography techniques: Out- guess [13], F5 [16], model...also compressed these images again since some of the steganography meth- ods are double compressing the images . Stego- images are generated by embedding...randomly chosen messages (in bits) into 1600 grayscale images using each of the four steganography techniques. A random message length was determined

Testing, Selection, and Implementation of Random Number Generators

DTIC Science & Technology

2008-07-01

Complexity and Lempel - Ziv Compression tests. This causes concern for cryptographic use but is not relevant for our applications. In fact, the features of...Linear Complexity, Lempel - Ziv Compression , and Matrix Rank test failures excluded. The Mersenne Twister is widely accepted by the community; in fact...searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments

Effect of Impact Damage and Open Hole on Compressive Strength of Hybrid Composite Laminates

NASA Technical Reports Server (NTRS)

Hiel, Clement; Brinson, H. F.

1993-01-01

Impact damage tolerance is a frequently listed design requirement for composites hardware. The effect of impact damage and open hole size on laminate compressive strength was studied on sandwich beam specimens which combine CFRP-GFRP hybrid skins and a syntactic foam core. Three test specimen configurations have been investigated for this study. The first two were sandwich beams which were loaded in pure bending (by four point flexure). One series had a skin damaged by impact, and the second series had a circular hole machined through one of the skins. The reduction of compressive strength with increasing damage (hole) size was compared. Additionally a third series of uniaxially loaded open hole compression coupons were tested to generate baseline data for comparison with both series of sandwich beams.

Solving the jitter problem in microwave compressed ultrafast electron diffraction instruments: Robust sub-50 fs cavity-laser phase stabilization

PubMed Central

Otto, M. R.; René de Cotret, L. P.; Stern, M. J.; Siwick, B. J.

2017-01-01

We demonstrate the compression of electron pulses in a high-brightness ultrafast electron diffraction instrument using phase-locked microwave signals directly generated from a mode-locked femtosecond oscillator. Additionally, a continuous-wave phase stabilization system that accurately corrects for phase fluctuations arising in the compression cavity from both power amplification and thermal drift induced detuning was designed and implemented. An improvement in the microwave timing stability from 100 fs to 5 fs RMS is measured electronically, and the long-term arrival time stability (>10 h) of the electron pulses improves to below our measurement resolution of 50 fs. These results demonstrate sub-relativistic ultrafast electron diffraction with compressed pulses that is no longer limited by laser-microwave synchronization. PMID:28852686

Femtosecond timing-jitter between photo-cathode laser and ultra-short electron bunches by means of hybrid compression

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Croia, M.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Gallo, A.; Gatti, G.; Giorgianni, F.; Giribono, A.; Li, W.; Lupi, S.; Mostacci, A.; Petrarca, M.; Piersanti, L.; Di Pirro, G.; Romeo, S.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.

2016-08-01

The generation of ultra-short electron bunches with ultra-low timing-jitter relative to the photo-cathode (PC) laser has been experimentally proved for the first time at the SPARC_LAB test-facility (INFN-LNF, Frascati) exploiting a two-stage hybrid compression scheme. The first stage employs RF-based compression (velocity-bunching), which shortens the bunch and imprints an energy chirp on it. The second stage is performed in a non-isochronous dogleg line, where the compression is completed resulting in a final bunch duration below 90 fs (rms). At the same time, the beam arrival timing-jitter with respect to the PC laser has been measured to be lower than 20 fs (rms). The reported results have been validated with numerical simulations.

ERGC: an efficient referential genome compression algorithm.

PubMed

Saha, Subrata; Rajasekaran, Sanguthevar

2015-11-01

Genome sequencing has become faster and more affordable. Consequently, the number of available complete genomic sequences is increasing rapidly. As a result, the cost to store, process, analyze and transmit the data is becoming a bottleneck for research and future medical applications. So, the need for devising efficient data compression and data reduction techniques for biological sequencing data is growing by the day. Although there exists a number of standard data compression algorithms, they are not efficient in compressing biological data. These generic algorithms do not exploit some inherent properties of the sequencing data while compressing. To exploit statistical and information-theoretic properties of genomic sequences, we need specialized compression algorithms. Five different next-generation sequencing data compression problems have been identified and studied in the literature. We propose a novel algorithm for one of these problems known as reference-based genome compression. We have done extensive experiments using five real sequencing datasets. The results on real genomes show that our proposed algorithm is indeed competitive and performs better than the best known algorithms for this problem. It achieves compression ratios that are better than those of the currently best performing algorithms. The time to compress and decompress the whole genome is also very promising. The implementations are freely available for non-commercial purposes. They can be downloaded from http://engr.uconn.edu/∼rajasek/ERGC.zip. rajasek@engr.uconn.edu. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Nonpainful wide-area compression inhibits experimental pain.

PubMed

Honigman, Liat; Bar-Bachar, Ofrit; Yarnitsky, David; Sprecher, Elliot; Granovsky, Yelena

2016-09-01

Compression therapy, a well-recognized treatment for lymphoedema and venous disorders, pressurizes limbs and generates massive non-noxious afferent sensory barrages. The aim of this study was to study whether such afferent activity has an analgesic effect when applied on the lower limbs, hypothesizing that larger compression areas will induce stronger analgesic effects, and whether this effect correlates with conditioned pain modulation (CPM). Thirty young healthy subjects received painful heat and pressure stimuli (47°C for 30 seconds, forearm; 300 kPa for 15 seconds, wrist) before and during 3 compression protocols of either SMALL (up to ankles), MEDIUM (up to knees), or LARGE (up to hips) compression areas. Conditioned pain modulation (heat pain conditioned by noxious cold water) was tested before and after each compression protocol. The LARGE protocol induced more analgesia for heat than the SMALL protocol (P < 0.001). The analgesic effect interacted with gender (P = 0.015). The LARGE protocol was more efficient for females, whereas the MEDIUM protocol was more efficient for males. Pressure pain was reduced by all protocols (P < 0.001) with no differences between protocols and no gender effect. Conditioned pain modulation was more efficient than the compression-induced analgesia. For the LARGE protocol, precompression CPM efficiency positively correlated with compression-induced analgesia. Large body area compression exerts an area-dependent analgesic effect on experimental pain stimuli. The observed correlation with pain inhibition in response to robust non-noxious sensory stimulation may suggest that compression therapy shares similar mechanisms with inhibitory pain modulation assessed through CPM.

Flow speed of the ablation vapors generated during laser drilling of CFRP with a continuous-wave laser beam

NASA Astrophysics Data System (ADS)

Faas, S.; Freitag, C.; Boley, S.; Berger, P.; Weber, R.; Graf, T.

2017-03-01

The hot plume of ablation products generated during the laser drilling process of carbon fiber reinforced plastics (CFRP) with a continuous-wave laser beam was analyzed by means of high-speed imaging. The formation of compression shocks was observed within the flow of the evaporated material, which is an indication of flow speeds well above the local speed of sound. The flow speed of the hot ablation products can be estimated by analyzing the position of these compression shocks. We investigated the temporal evolution of the flow speed during the drilling process and the influence of the average laser power on the flow speed. The flow speed increases with increasing average laser powers. The moment of drilling through the material changes the conditions for the drilling process and was confirmed to influence the flow speed of the ablated material. Compression shocks can also be observed during laser cutting of CFRP with a moving laser beam.

Flexible theta sequence compression mediated via phase precessing interneurons

PubMed Central

Chadwick, Angus; van Rossum, Mark CW; Nolan, Matthew F

2016-01-01

Encoding of behavioral episodes as spike sequences during hippocampal theta oscillations provides a neural substrate for computations on events extended across time and space. However, the mechanisms underlying the numerous and diverse experimentally observed properties of theta sequences remain poorly understood. Here we account for theta sequences using a novel model constrained by the septo-hippocampal circuitry. We show that when spontaneously active interneurons integrate spatial signals and theta frequency pacemaker inputs, they generate phase precessing action potentials that can coordinate theta sequences in place cell populations. We reveal novel constraints on sequence generation, predict cellular properties and neural dynamics that characterize sequence compression, identify circuit organization principles for high capacity sequential representation, and show that theta sequences can be used as substrates for association of conditioned stimuli with recent and upcoming events. Our results suggest mechanisms for flexible sequence compression that are suited to associative learning across an animal’s lifespan. DOI: http://dx.doi.org/10.7554/eLife.20349.001 PMID:27929374

A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

PubMed

Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

2011-04-01

A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. © 2011 IEEE

Mach 5 bow shock control by a nanosecond pulse surface dielectric barrier discharge

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

Nishihara, M.; Takashima, K.; Rich, J. W.

2011-06-15

Bow shock perturbations in a Mach 5 air flow, produced by low-temperature, nanosecond pulse, and surface dielectric barrier discharge (DBD), are detected by phase-locked schlieren imaging. A diffuse nanosecond pulse discharge is generated in a DBD plasma actuator on a surface of a cylinder model placed in air flow in a small scale blow-down supersonic wind tunnel. Discharge energy coupled to the actuator is 7.3-7.8 mJ/pulse. Plasma temperature inferred from nitrogen emission spectra is a few tens of degrees higher than flow stagnation temperature, T = 340 {+-} 30 K. Phase-locked Schlieren images are used to detect compression waves generatedmore » by individual nanosecond discharge pulses near the actuator surface. The compression wave propagates upstream toward the baseline bow shock standing in front of the cylinder model. Interaction of the compression wave and the bow shock causes its displacement in the upstream direction, increasing shock stand-off distance by up to 25%. The compression wave speed behind the bow shock and the perturbed bow shock velocity are inferred from the Schlieren images. The effect of compression waves generated by nanosecond discharge pulses on shock stand-off distance is demonstrated in a single-pulse regime (at pulse repetition rates of a few hundred Hz) and in a quasi-continuous mode (using a two-pulse sequence at a pulse repetition rate of 100 kHz). The results demonstrate feasibility of hypersonic flow control by low-temperature, repetitive nanosecond pulse discharges.« less

Intramuscular pressures beneath elastic and inelastic leggings

NASA Technical Reports Server (NTRS)

Murthy, G.; Ballard, R. E.; Breit, G. A.; Watenpaugh, D. E.; Hargens, A. R.

1994-01-01

Leg compression devices have been used extensively by patients to combat chronic venous insufficiency and by astronauts to counteract orthostatic intolerance following spaceflight. However, the effects of elastic and inelastic leggings on the calf muscle pump have not been compared. The purpose of this study was to compare in normal subjects the effects of elastic and inelastic compression on leg intramuscular pressure (IMP), an objective index of calf muscle pump function. IMP in soleus and tibialis anterior muscles was measured with transducer-tipped catheters. Surface compression between each legging and the skin was recorded with an air bladder. Subjects were studied under three conditions: (1) control (no legging), (2) elastic legging, and (3) inelastic legging. Pressure data were recorded for each condition during recumbency, sitting, standing, walking, and running. Elastic leggings applied significantly greater surface compression during recumbency (20 +/- 1 mm Hg, mean +/- SE) than inelastic leggings (13 +/- 2 mm Hg). During recumbency, elastic leggings produced significantly higher soleus IMP of 25 +/- 1 mm Hg and tibialis anterior IMP of 28 +/- 1 mm Hg compared to 17 +/- 1 mm Hg and 20 +/- 2 mm Hg, respectively, generated by inelastic leggings and 8 +/- 1 mm Hg and 11 +/- 1 mm Hg, respectively, without leggings. During sitting, walking, and running, however, peak IMPs generated in the muscular compartments by elastic and inelastic leggings were similar. Our results suggest that elastic leg compression applied over a long period in the recumbent posture may impede microcirculation and jeopardize tissue viability.(ABSTRACT TRUNCATED AT 250 WORDS).

Three-dimensional integral imaging displays using a quick-response encoded elemental image array: an overview

NASA Astrophysics Data System (ADS)

Markman, A.; Javidi, B.

2016-06-01

Quick-response (QR) codes are barcodes that can store information such as numeric data and hyperlinks. The QR code can be scanned using a QR code reader, such as those built into smartphone devices, revealing the information stored in the code. Moreover, the QR code is robust to noise, rotation, and illumination when scanning due to error correction built in the QR code design. Integral imaging is an imaging technique used to generate a three-dimensional (3D) scene by combining the information from two-dimensional (2D) elemental images (EIs) each with a different perspective of a scene. Transferring these 2D images in a secure manner can be difficult. In this work, we overview two methods to store and encrypt EIs in multiple QR codes. The first method uses run-length encoding with Huffman coding and the double-random-phase encryption (DRPE) to compress and encrypt an EI. This information is then stored in a QR code. An alternative compression scheme is to perform photon-counting on the EI prior to compression. Photon-counting is a non-linear transformation of data that creates redundant information thus improving image compression. The compressed data is encrypted using the DRPE. Once information is stored in the QR codes, it is scanned using a smartphone device. The information scanned is decompressed and decrypted and an EI is recovered. Once all EIs have been recovered, a 3D optical reconstruction is generated.

Compression-triggered instabilities of multi-layer systems: From thin elastic membranes to lipid bilayers on flexible substrates

NASA Astrophysics Data System (ADS)

Stone, Howard A.

2013-03-01

Instabilities are triggered when elastic materials are subjected to compression. We explore new features of two distinct systems of this type. First, we describe a two-layer polymeric system under biaxial compressive stress, which exhibits a repetitive wrinkle-to-fold transition that subsequently generates a hierarchical network of folds during reorganization of the stress field. The folds delineate individual domains, and each domain subdivides into smaller ones over multiple generations. By modifying the boundary conditions and geometry, we demonstrate control over the final network morphology. Some analogies to the venation pattern of leaves are indicated. Second, motivated by the confined configurations common to cells, which are wrapped in lipid bilayer membranes, we study a lipid bilayer, coupled to an elastic sheet, and demonstrate that, upon straining, the confined lipid membrane is able to passively regulate its area. In particular, by stretching the elastic support, the bilayer laterally expands without rupture by fusing adhered lipid vesicles; upon compression, lipid tubes grow out of the membrane plane, thus reducing its area. These transformations are reversible, as we show using cycles of expansion and compression, and closely reproduce membrane processes found in cells during area regulation. The two distinct systems illustrate the influence of the substrate on finite amplitude shape changes, for which we describe the time-dependent shape evolution as the stress relaxes. This talk describes joint research with Manouk Abkarian, Marino Arroyo, Pilnam Kim, Mohammad Rahimi and Margarita Staykova.

PU-ICE Summary Information.

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

Moore, Michael

The Generator Knowledge Report for the Plutonium Isentropic Compression Experiment Containment Systems (GK Report) provides information for the Plutonium Isentropic Compression Experiment (Pu- ICE) program to support waste management and characterization efforts. Attachment 3-18 presents generator knowledge (GK) information specific to the eighteenth Pu-ICE conducted in August 2015, also known as ‘Shot 18 (Aug 2015) and Pu-ICE Z-2841 (1).’ Shot 18 (Aug 2015) was generated on August 28, 2015 (1). Calculations based on the isotopic content of Shot 18 (Aug 2015) and the measured mass of the containment system demonstrate the post-shot containment system is low-level waste (LLW). Therefore, thismore » containment system will be managed at Sandia National Laboratory/New Mexico (SNL/NM) as LLW. Attachment 3-18 provides documentation of the TRU concentration and documents the concentration of any hazardous constituents.« less

Multi-axis dose accumulation of noninvasive image-guided breast brachytherapy through biomechanical modeling of tissue deformation using the finite element method

PubMed Central

Ghadyani, Hamid R.; Bastien, Adam D.; Lutz, Nicholas N.; Hepel, Jaroslaw T.

2015-01-01

Purpose Noninvasive image-guided breast brachytherapy delivers conformal HDR 192Ir brachytherapy treatments with the breast compressed, and treated in the cranial-caudal and medial-lateral directions. This technique subjects breast tissue to extreme deformations not observed for other disease sites. Given that, commercially-available software for deformable image registration cannot accurately co-register image sets obtained in these two states, a finite element analysis based on a biomechanical model was developed to deform dose distributions for each compression circumstance for dose summation. Material and methods The model assumed the breast was under planar stress with values of 30 kPa for Young's modulus and 0.3 for Poisson's ratio. Dose distributions from round and skin-dose optimized applicators in cranial-caudal and medial-lateral compressions were deformed using 0.1 cm planar resolution. Dose distributions, skin doses, and dose-volume histograms were generated. Results were examined as a function of breast thickness, applicator size, target size, and offset distance from the center. Results Over the range of examined thicknesses, target size increased several millimeters as compression thickness decreased. This trend increased with increasing offset distances. Applicator size minimally affected target coverage, until applicator size was less than the compressed target size. In all cases, with an applicator larger or equal to the compressed target size, > 90% of the target covered by > 90% of the prescription dose. In all cases, dose coverage became less uniform as offset distance increased and average dose increased. This effect was more pronounced for smaller target–applicator combinations. Conclusions The model exhibited skin dose trends that matched MC-generated benchmarking results within 2% and clinical observations over a similar range of breast thicknesses and target sizes. The model provided quantitative insight on dosimetric treatment variables over a range of clinical circumstances. These findings highlight the need for careful target localization and accurate identification of compression thickness and target offset. PMID:25829938

Hybrid fluid-particle simulation of whistler-mode waves in a compressed dipole magnetic field: Implications for dayside high-latitude chorus

NASA Astrophysics Data System (ADS)

da Silva, C. L.; Wu, S.; Denton, R. E.; Hudson, M. K.; Millan, R. M.

2017-01-01

In this work we present a methodology for simulating whistler-mode waves self-consistently generated by electron temperature anisotropy in the inner magnetosphere. We present simulation results using a hybrid fluid/particle-in-cell code that treats the hot, anisotropic (i.e., ring current) electron population as particles and the background (i.e., the cold and inertialess) electrons as fluid. Since the hot electrons are only a small fraction of the total population, warm (and isotropic) particle electrons are added to the simulation to increase the fraction of particles with mass, providing a more accurate characterization of the wave dispersion relation. Ions are treated as a fixed background of positive charge density. The plasma transport equations are coupled to Maxwell's equations and solved in a meridional plane (a 2-D simulation with 3-D fields). We use a curvilinear coordinate system that follows the topological curvature of Earth's geomagnetic field lines, based on an analytic expression for a compressed dipole magnetic field. Hence, we are able to simulate whistler wave generation at dawn (pure dipole field lines) and dayside (compressed dipole) by simply adjusting one scalar quantity. We demonstrate how, on the dayside, whistler-mode waves can be locally generated at a range of high latitudes, within pockets of minimum magnetic field, and propagate equatorward. The obtained dayside waves (in a compressed dipole field) have similar amplitude and frequency content to their dawn sector counterparts (in a pure dipole field) but tend to propagate more field aligned.

Wrinkling of solidifying polymeric coatings

NASA Astrophysics Data System (ADS)

Basu, Soumendra Kumar

2005-07-01

In coatings, wrinkles are viewed as defects or as desired features for low gloss, and texture. In either case, discovering the origin of wrinkles and the conditions that lead to their formation is important. This research examines what wrinkling requires and proposes a mechanism to explain the observations. All curing wrinkling coatings contain multi-functional reactants. Upon curing, all develop a depth-wise gradient in solidification that result in a cross-linked elastic skin atop a viscous bottom layer. It is hypothesized that compressive stress develops in the skin when liquid below diffuses up into the skin. High enough compressive stress buckles the skin to produce wrinkles. The hypothesis is substantiated by experimental and theoretical evidences. Effects of various application and compositional parameters on wrinkle size in a liquid-applied acrylic coating and a powder-applied epoxy coating were examined. All three components, namely resin, cross-linker and catalyst blocked with at least equimolar volatile blocker, proved to be required for wrinkling. The wrinkling phenomenon was modeled with a theory that accounts for gradient generation, cross-linking reaction and skinning; predictions compared well with observations. Two-layer non-curing coatings that have a stiff elastic layer atop a complaint elastic bottom layer wrinkled when the top layer is compressed. The top layer was compressed by either moisture absorption or differential thermal expansion. Experimental observations compared well with predictions from a theory based on force balance in multilayer systems subjected to differential contraction or expansion. A model based on the Flory-Rehner free energy of a constrained cross-linked gel was constructed that predicts the compressive stress generated in a coating when it absorbs solvent. Linear stability analysis predicts that when a compressed elastic layer is attached atop a viscous layer, it is always unstable to buckles whose wavelength exceeds a critical value; more cross-linking and poor solvent produce higher wavelength, lower amplitude wrinkles. When a compressed elastic layer is attached atop an elastic layer and subjected to more than a critical compressive stress, it is unstable to intermediate wavelengths of buckling; better solvent, higher ratio of bottom-to-top layer thickness, and lower bottom layer modulus produce higher wavelength, higher amplitude wrinkles.

Magnetic Flux Compression Concept for Aerospace Propulsion and Power

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Robertson, Tony; Hawk, Clark W.; Turner, Matt; Koelfgen, Syri

2000-01-01

The objective of this research is to investigate system level performance and design issues associated with magnetic flux compression devices for aerospace power generation and propulsion. The proposed concept incorporates the principles of magnetic flux compression for direct conversion of nuclear/chemical detonation energy into electrical power. Specifically a magnetic field is compressed between an expanding detonation driven diamagnetic plasma and a stator structure formed from a high temperature superconductor (HTSC). The expanding plasma cloud is entirely confined by the compressed magnetic field at the expense of internal kinetic energy. Electrical power is inductively extracted, and the detonation products are collimated and expelled through a magnetic nozzle. The long-term development of this highly integrated generator/propulsion system opens up revolutionary NASA Mission scenarios for future interplanetary and interstellar spacecraft. The unique features of this concept with respect to future space travel opportunities are as follows: ability to implement high energy density chemical detonations or ICF microfusion bursts as the impulsive diamagnetic plasma source; high power density system characteristics constrain the size, weight, and cost of the vehicle architecture; provides inductive storage pulse power with a very short pulse rise time; multimegajoule energy bursts/terawatt power bursts; compact pulse power driver for low-impedance dense plasma devices; utilization of low cost HTSC material and casting technology to increase magnetic flux conservation and inductive energy storage; improvement in chemical/nuclear-to-electric energy conversion efficiency and the ability to generate significant levels of thrust with very high specific impulse; potential for developing a small, lightweight, low cost, self-excited integrated propulsion and power system suitable for space stations, planetary bases, and interplanetary and interstellar space travel; potential for attaining specific impulses approaching 10 (exp 6) seconds, which would enable missions to the outer planets within ten years and missions at interstellar distances within fifty years.

Generation of 360 ps laser pulse with 3 J energy by stimulated Brillouin scattering with a nonfocusing scheme.

PubMed

Zhu, Xuehua; Wang, Yulei; Lu, Zhiwei; Zhang, Hengkang

2015-09-07

A new technique for generating high energy sub-400 picosecond laser pulses is presented in this paper. The temporally super-Gaussian-shaped laser pulses are used as light source. When the forward pump is reflected by the rear window of SBS cell, the frequency component that fulfills Brillouin frequency shift in its sideband spectrum works as a seed and excites SBS, which results in efficient compression of the incident pump pulse. First the pulse compression characteristics of 20th-order super-Gaussian temporally shaped pulses with 5 ns duration are analyzed theoretically. Then experiment is carried out with a narrow-band high power Nd:glass laser system at the double-frequency and wavelength of 527 nm which delivers 5 ns super-Gaussian temporally shaped pulses with single pulse energy over 10 J. FC-40 is used as the active SBS medium for its brief phonon lifetime and high power capacity. In the experiment, the results agree well with the numerical calculations. With pump energy of 5.36J, the compression of pulse duration from 5 ns to 360 ps is obtained. The output energy is 3.02 J and the peak-power is magnified 8.3 times. Moreover, the compressed pulse shows a high stability because it is initiated by the feedback of rear window rather than the thermal noise distributing inside the medium. This technique of generating high energy hundred picosecond laser pulses has simple structure and is easy to operate, and it also can be scaled to higher energy pulse compression in the future. Meanwhile, it should also be taken into consideration that in such a nonfocusing scheme, the noise-initiated SBS would increase the distortion on the wavefront of Stokes beam to some extent, and the pump energy should be controlled below the threshold of noise-initiated SBS.

Adaptive sampler

DOEpatents

Watson, Bobby L.; Aeby, Ian

1982-01-01

An adaptive data compression device for compressing data having variable frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

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

NASA Astrophysics Data System (ADS)

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.

From Red Cells to Soft Porous Lubrication

NASA Astrophysics Data System (ADS)

Gacka, T.; Nathan, R.; Wu, L.; Wu, Q.; Cbmss Laboratory Team; Chinese Academy Of Sci. Team

2011-11-01

Feng and Weinbaum (J. Fluid. Mech., 422, 282, 2000), inspired by the enhanced lift phenomena in downhill skiing, developed a new lubrication theory for highly compressible porous media where significantly increased lifting force was predicted as a planing surface glided over a soft porous layer; suggesting superior potential use of porous media for soft lubrication. In this study, we experimentally examine the lift generation phenomena by developing a novel soft porous bearing that consists of a running conveyer belt covered with a soft, 100% polyester, porous sheet, and a stationary, fully instrumented, inclined, planar, upper board. Pore pressure was generated as the upper boundary glides over the soft porous bearing and was measured by pressure sensors. One observed that the pore pressure distribution is consistent with predictions by Feng and Weinbaum (2000), and is a function of the relative velocity between the planing surface and the running belt, the mechanical properties (e.g. porosity, permeability and stiffness) and thickness of the porous layer, as well as the compression ratios at the leading and trailing edges. A load cell is used to characterize the performance of the porous bearing, by comparing pore pressure to total lifting forces. The study presented herein significantly improves our understanding of the behavior of highly compressible porous media under fast compression.

A JPEG backward-compatible HDR image compression

NASA Astrophysics Data System (ADS)

Korshunov, Pavel; Ebrahimi, Touradj

2012-10-01

High Dynamic Range (HDR) imaging is expected to become one of the technologies that could shape next generation of consumer digital photography. Manufacturers are rolling out cameras and displays capable of capturing and rendering HDR images. The popularity and full public adoption of HDR content is however hindered by the lack of standards in evaluation of quality, file formats, and compression, as well as large legacy base of Low Dynamic Range (LDR) displays that are unable to render HDR. To facilitate wide spread of HDR usage, the backward compatibility of HDR technology with commonly used legacy image storage, rendering, and compression is necessary. Although many tone-mapping algorithms were developed for generating viewable LDR images from HDR content, there is no consensus on which algorithm to use and under which conditions. This paper, via a series of subjective evaluations, demonstrates the dependency of perceived quality of the tone-mapped LDR images on environmental parameters and image content. Based on the results of subjective tests, it proposes to extend JPEG file format, as the most popular image format, in a backward compatible manner to also deal with HDR pictures. To this end, the paper provides an architecture to achieve such backward compatibility with JPEG and demonstrates efficiency of a simple implementation of this framework when compared to the state of the art HDR image compression.

Ultrasonic Measurement of Strain Distribution Inside Object Cyclically Compressed by Dual Acoustic Radiation Force

NASA Astrophysics Data System (ADS)

Odagiri, Yoshitaka; Hasegawa, Hideyuki; Kanai, Hiroshi

2008-05-01

One possible way to evaluate acupuncture therapy quantitatively is to measure the change in the elastic property of muscle after application of the therapy. Many studies have been conducted to measure mechanical properties of tissues using ultrasound-induced acoustic radiation force. To assess mechanical properties, strain must be generated in an object. However, a single radiation force is not effective because it mainly generates translational motion when the object is much harder than the surrounding medium. In this study, two cyclic radiation forces are simultaneously applied to a muscle phantom from two opposite horizontal directions so that the object is cyclically compressed in the horizontal direction. By the horizontal compression, the object is expanded vertically based on its incompressibility. The resultant vertical displacement is measured using another ultrasound pulse. Two ultrasonic transducers for actuation were both driven by the sum of two continuous sinusoidal signals at two slightly different frequencies [1 MHz and (1 M + 5) Hz]. The displacement of several micrometers in amplitude, which fluctuated at 5 Hz, was measured by the ultrasonic phased tracking method. Increase in thickness inside the object was observed just when acoustic radiation forces increased. Such changes in thickness correspond to vertical expansion due to horizontal compression.

System for generating pluralities of optical pulses with predetermined frequencies in a temporally and spatially overlapped relationship

DOEpatents

Meyerhofer, David D.; Schmid, Ansgar W.; Chuang, Yung-ho

1992-01-01

Ultra short (pico second and shorter) laser pulses having components of different frequency which are overlapped coherently in space and with a predetermined constant relationship in time, are generated and may be used in applications where plural spectrally separate, time-synchronized pulses are needed as in wave-length resolved spectroscopy and spectral pump probe measurements for characterization of materials. A Chirped Pulse Amplifier (CPA), such as a regenerative amplifier, which provides amplified, high intensity pulses at the output thereof which have the same spatial intensity profile, is used to process a series of chirped pulses, each with a different central frequency (the desired frequencies contained in the output pulses). Each series of chirped pulses is obtained from a single chirped pulse by spectral windowing with a mask in a dispersive expansion stage ahead of the laser amplifier. The laser amplifier amplifies the pulses and provides output pulses with like spatial and temporal profiles. A compression stage then compresses the amplified pulses. All the individual pulses of different frequency, which originated in each single chirped pulse, are compressed and thereby coherently overlapped in space and time. The compressed pulses may be used for the foregoing purposes and other purposes wherien pulses having a plurality of discrete frequency components are required.

System for generating pluralities of optical pulses with predetermined frequencies in a temporally and spatially overlapped relationship

DOEpatents

Meyerhofer, D.D.; Schmid, A.W.; Chuang, Y.

1992-03-10

Ultrashort (pico second and shorter) laser pulses having components of different frequency which are overlapped coherently in space and with a predetermined constant relationship in time, are generated and may be used in applications where plural spectrally separate, time-synchronized pulses are needed as in wave-length resolved spectroscopy and spectral pump probe measurements for characterization of materials. A Chirped Pulse Amplifier (CPA), such as a regenerative amplifier, which provides amplified, high intensity pulses at the output thereof which have the same spatial intensity profile, is used to process a series of chirped pulses, each with a different central frequency (the desired frequencies contained in the output pulses). Each series of chirped pulses is obtained from a single chirped pulse by spectral windowing with a mask in a dispersive expansion stage ahead of the laser amplifier. The laser amplifier amplifies the pulses and provides output pulses with like spatial and temporal profiles. A compression stage then compresses the amplified pulses. All the individual pulses of different frequency, which originated in each single chirped pulse, are compressed and thereby coherently overlapped in space and time. The compressed pulses may be used for the foregoing purposes and other purposes wherien pulses having a plurality of discrete frequency components are required. 4 figs.

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

Goodson, J.O.

This is the first of three volumes which document the historical development of the first US compressed-air energy storage (CAES) Power-generation facility. Volume 1 is a background report and presents a chronicle of the development of the CAES facility from the early interest in CAES until inception of engineering/construction on August 11, 1988. The 110 MW - 26 hr CAES plant is owned and operated by Alabama Electric Cooperative, Inc. (AEC) of Andalusia, Alabama. The plant is the first CAES plant in the United States and the world's first CAES facility incorporating a recuperator to improve efficiency. The plant suppliesmore » competitively priced peaking power to the AEC owner members. The economics of CAES-produced power is attractive because the energy-intensive air-compression mode is powered by relatively inexpensive base-load power external to the CAES plant. The compressed-air energy is stored underground until needed, and during the power-production mode, the only fuel required is that to heat the compressed air to expander-inlet temperature. The project development for AEC's CAES plant involved much planning and preliminary design work. Specifically, this included load and generation-planning studies, power-supply selections, conceptual designs, project administration, air-storage cavern and turbomachinery specifications and design, contract requirements, environmental and licensing issues, and construction planning.« less

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

Goodson, J.O.

This is the first of three volumes which document the historical development of the first US compressed-air energy storage (CAES) Power-generation facility. Volume 1 is a background report and presents a chronicle of the development of the CAES facility from the early interest in CAES until inception of engineering/construction on August 11, 1988. The 110 MW - 26 hr CAES plant is owned and operated by Alabama Electric Cooperative, Inc. (AEC) of Andalusia, Alabama. The plant is the first CAES plant in the United States and the world`s first CAES facility incorporating a recuperator to improve efficiency. The plant suppliesmore » competitively priced peaking power to the AEC owner members. The economics of CAES-produced power is attractive because the energy-intensive air-compression mode is powered by relatively inexpensive base-load power external to the CAES plant. The compressed-air energy is stored underground until needed, and during the power-production mode, the only fuel required is that to heat the compressed air to expander-inlet temperature. The project development for AEC`s CAES plant involved much planning and preliminary design work. Specifically, this included load and generation-planning studies, power-supply selections, conceptual designs, project administration, air-storage cavern and turbomachinery specifications and design, contract requirements, environmental and licensing issues, and construction planning.« less

Does the Hertz solution estimate pressures correctly in diamond indentor experiments?

NASA Astrophysics Data System (ADS)

Bruno, M. S.; Dunn, K. J.

1986-05-01

The Hertz solution has been widely used to estimate pressures in a spherical indentor against flat matrix type high pressure experiments. It is usually assumed that the pressure generated when compressing a sample between the indentor and substrate is the same as that generated when compressing an indentor against a flat surface with no sample present. A non-linear finite element analysis of this problem has shown that the situation is far more complex. The actual peak pressure in the sample is highly dependent on plastic deformation and the change in material properties due to hydrostatic pressure. An analysis with two material models is presented and compared with the Hertz solution.

Experimental demonstration of fiber optical parametric chirped-pulse amplification

NASA Astrophysics Data System (ADS)

Zhou, Yue; Cheung, Kim K. Y.; Chui, P. C.; Wong, Kenneth K. Y.

2010-02-01

A fiber optical parametric chirped-pulse amplifier (FOPCPA) is experimentally demonstrated. A 1.76 ps signal at 1542 nm with a peak power of 20 mW is broadened to 40 ps, and then amplified by a 100-ps pulsed pump at 1560 nm. The corresponding idler at 1578 nm is generated as the FOPCPA output. The same medium used to stretch the signal is deployed to compress the idler to 3.8 ps, and another spool of fiber is deployed to further compress the idler to 1.87 ps. The peak power of the compressed idler is 2 W, which corresponds to a gain of 20 dB.

Wavelet-based scalable L-infinity-oriented compression.

PubMed

Alecu, Alin; Munteanu, Adrian; Cornelis, Jan P H; Schelkens, Peter

2006-09-01

Among the different classes of coding techniques proposed in literature, predictive schemes have proven their outstanding performance in near-lossless compression. However, these schemes are incapable of providing embedded L(infinity)-oriented compression, or, at most, provide a very limited number of potential L(infinity) bit-stream truncation points. We propose a new multidimensional wavelet-based L(infinity)-constrained scalable coding framework that generates a fully embedded L(infinity)-oriented bit stream and that retains the coding performance and all the scalability options of state-of-the-art L2-oriented wavelet codecs. Moreover, our codec instantiation of the proposed framework clearly outperforms JPEG2000 in L(infinity) coding sense.

Consistent Initial Conditions for the DNS of Compressible Turbulence

NASA Technical Reports Server (NTRS)

Ristorcelli, J. R.; Blaisdell, G. A.

1996-01-01

Relationships between diverse thermodynamic quantities appropriate to weakly compressible turbulence are derived. It is shown that for turbulence of a finite turbulent Mach number there is a finite element of compressibility. A methodology for generating initial conditions for the fluctuating pressure, density and dilatational velocity is given which is consistent with finite Mach number effects. Use of these initial conditions gives rise to a smooth development of the flow, in contrast to cases in which these fields are specified arbitrarily or set to zero. Comparisons of the effect of different types of initial conditions are made using direct numerical simulation of decaying isotropic turbulence.

Isentropic compression of argon

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

Veeser, L.R.; Ekdahl, C.A.; Oona, H.

1997-06-01

The compression was done in an MC-1 flux compression (explosive) generator, in order to study the transition from an insulator to a conductor. Since conductivity signals were observed in all the experiments (except when the probe is removed), both the Teflon and the argon are becoming conductive. The conductivity could not be determined (Teflon insulation properties unknown), but it could be bounded as being {sigma}=1/{rho}{le}8({Omega}cm){sub -1}, because when the Teflon breaks down, the dielectric constant is reduced. The Teflon insulator problem remains, and other ways to better insulate the probe or to measure the conductivity without a probe is beingmore » sought.« less

MER Telemetry Processor

NASA Technical Reports Server (NTRS)

Lee, Hyun H.

2012-01-01

MERTELEMPROC processes telemetered data in data product format and generates Experiment Data Records (EDRs) for many instruments (HAZCAM, NAVCAM, PANCAM, microscopic imager, Moessbauer spectrometer, APXS, RAT, and EDLCAM) on the Mars Exploration Rover (MER). If the data is compressed, then MERTELEMPROC decompresses the data with an appropriate decompression algorithm. There are two compression algorithms (ICER and LOCO) used in MER. This program fulfills a MER specific need to generate Level 1 products within a 60-second time requirement. EDRs generated by this program are used by merinverter, marscahv, marsrad, and marsjplstereo to generate higher-level products for the mission operations. MERTELEPROC was the first GDS program to process the data product. Metadata of the data product is in XML format. The software allows user-configurable input parameters, per-product processing (not streambased processing), and fail-over is allowed if the leading image header is corrupted. It is used within the MER automated pipeline. MERTELEMPROC is part of the OPGS (Operational Product Generation Subsystem) automated pipeline, which analyzes images returned by in situ spacecraft and creates level 1 products to assist in operations, science, and outreach.

Soliton-plasma nonlinear dynamics in mid-IR gas-filled hollow-core fibers.

PubMed

Selim Habib, Md; Markos, Christos; Bang, Ole; Bache, Morten

2017-06-01

We investigate numerically soliton-plasma interaction in a noble-gas-filled silica hollow-core anti-resonant fiber pumped in the mid-IR at 3.0 μm. We observe multiple soliton self-compression stages due to distinct stages where either the self-focusing or the self-defocusing nonlinearity dominates. Specifically, the parameters may be tuned so the competing plasma self-defocusing nonlinearity only dominates over the Kerr self-focusing nonlinearity around the soliton self-compression stage, where the increasing peak intensity on the leading pulse edge initiates a competing self-defocusing plasma nonlinearity acting nonlocally on the trailing edge, effectively preventing soliton formation there. As the plasma switches off after the self-compression stage, self-focusing dominates again, initiating another soliton self-compression stage in the trailing edge. This process is accompanied by supercontinuum generation spanning 1-4 μm. We find that the spectral coherence drops as the secondary compression stage is initiated.

FaStore - a space-saving solution for raw sequencing data.

PubMed

Roguski, Lukasz; Ochoa, Idoia; Hernaez, Mikel; Deorowicz, Sebastian

2018-03-29

The affordability of DNA sequencing has led to the generation of unprecedented volumes of raw sequencing data. These data must be stored, processed, and transmitted, which poses significant challenges. To facilitate this effort, we introduce FaStore, a specialized compressor for FASTQ files. FaStore does not use any reference sequences for compression, and permits the user to choose from several lossy modes to improve the overall compression ratio, depending on the specific needs. FaStore in the lossless mode achieves a significant improvement in compression ratio with respect to previously proposed algorithms. We perform an analysis on the effect that the different lossy modes have on variant calling, the most widely used application for clinical decision making, especially important in the era of precision medicine. We show that lossy compression can offer significant compression gains, while preserving the essential genomic information and without affecting the variant calling performance. FaStore can be downloaded from https://github.com/refresh-bio/FaStore. sebastian.deorowicz@polsl.pl. Supplementary data are available at Bioinformatics online.

LFQC: a lossless compression algorithm for FASTQ files

PubMed Central

Nicolae, Marius; Pathak, Sudipta; Rajasekaran, Sanguthevar

2015-01-01

Motivation: Next Generation Sequencing (NGS) technologies have revolutionized genomic research by reducing the cost of whole genome sequencing. One of the biggest challenges posed by modern sequencing technology is economic storage of NGS data. Storing raw data is infeasible because of its enormous size and high redundancy. In this article, we address the problem of storage and transmission of large FASTQ files using innovative compression techniques. Results: We introduce a new lossless non-reference based FASTQ compression algorithm named Lossless FASTQ Compressor. We have compared our algorithm with other state of the art big data compression algorithms namely gzip, bzip2, fastqz (Bonfield and Mahoney, 2013), fqzcomp (Bonfield and Mahoney, 2013), Quip (Jones et al., 2012), DSRC2 (Roguski and Deorowicz, 2014). This comparison reveals that our algorithm achieves better compression ratios on LS454 and SOLiD datasets. Availability and implementation: The implementations are freely available for non-commercial purposes. They can be downloaded from http://engr.uconn.edu/rajasek/lfqc-v1.1.zip. Contact: rajasek@engr.uconn.edu PMID:26093148

Shear wave pulse compression for dynamic elastography using phase-sensitive optical coherence tomography

NASA Astrophysics Data System (ADS)

Nguyen, Thu-Mai; Song, Shaozhen; Arnal, Bastien; Wong, Emily Y.; Huang, Zhihong; Wang, Ruikang K.; O'Donnell, Matthew

2014-01-01

Assessing the biomechanical properties of soft tissue provides clinically valuable information to supplement conventional structural imaging. In the previous studies, we introduced a dynamic elastography technique based on phase-sensitive optical coherence tomography (PhS-OCT) to characterize submillimetric structures such as skin layers or ocular tissues. Here, we propose to implement a pulse compression technique for shear wave elastography. We performed shear wave pulse compression in tissue-mimicking phantoms. Using a mechanical actuator to generate broadband frequency-modulated vibrations (1 to 5 kHz), induced displacements were detected at an equivalent frame rate of 47 kHz using a PhS-OCT. The recorded signal was digitally compressed to a broadband pulse. Stiffness maps were then reconstructed from spatially localized estimates of the local shear wave speed. We demonstrate that a simple pulse compression scheme can increase shear wave detection signal-to-noise ratio (>12 dB gain) and reduce artifacts in reconstructing stiffness maps of heterogeneous media.

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

NASA Astrophysics Data System (ADS)

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.

Partial oxidation power plant with reheating and method thereof

DOEpatents

Newby, Richard A.; Yang, Wen-Ching; Bannister, Ronald L.

1999-01-01

A system and method for generating power having an air compression/partial oxidation system, a turbine, and a primary combustion system. The air compression/partial oxidation system receives a first air stream and a fuel stream and produces a first partially oxidized fuel stream and a first compressed air stream therefrom. The turbine expands the first partially oxidized fuel stream while being cooled by the first compressed air stream to produce a heated air stream. The heated air stream is injected into the expanding first partially oxidized fuel stream, thereby reheating it in the turbine. A second partially oxidized fuel stream is emitted from the turbine. The primary combustion system receives said second partially oxidized fuel stream and a second air stream, combusts said second partially oxidized fuel stream, and produces rotating shaft power and an emission stream therefrom.

Laser-driven magnetic-flux compression in high-energy-density plasmas.

PubMed

Gotchev, O V; Chang, P Y; Knauer, J P; Meyerhofer, D D; Polomarov, O; Frenje, J; Li, C K; Manuel, M J-E; Petrasso, R D; Rygg, J R; Séguin, F H; Betti, R

2009-11-20

The demonstration of magnetic field compression to many tens of megagauss in cylindrical implosions of inertial confinement fusion targets is reported for the first time. The OMEGA laser [T. R. Boehly, Opt. Commun. 133, 495 (1997)10.1016/S0030-4018(96)00325-2] was used to implode cylindrical CH targets filled with deuterium gas and seeded with a strong external field (>50 kG) from a specially developed magnetic pulse generator. This seed field was trapped (frozen) in the shock-heated gas fill and compressed by the imploding shell at a high implosion velocity, minimizing the effect of resistive flux diffusion. The magnetic fields in the compressed core were probed via proton deflectrometry using the fusion products from an imploding D3He target. Line-averaged magnetic fields between 30 and 40 MG were observed.

Avalanches in compressed Ti-Ni shape-memory porous alloys: An acoustic emission study.

PubMed

Soto-Parra, Daniel; Zhang, Xiaoxin; Cao, Shanshan; Vives, Eduard; Salje, Ekhard K H; Planes, Antoni

2015-06-01

Mechanical avalanches during compression of martensitic porous Ti-Ni have been characterized by high-frequency acoustic emission (AE). Two sequences of AE signals were found in the same sample. The first sequence is mainly generated by detwinning at the early stages of compression while fracture dominates the later stages. Fracture also determines the catastrophic failure (big crash). For high-porosity samples, the AE energies of both sequences display power-law distributions with exponents ɛ≃2 (twinning) and 1.7 (fracture). The two power laws confirm that twinning and fracture both lead to avalanche criticality during compression. As twinning precedes fracture, the observation of twinning allows us to predict incipient fracture of the porous shape memory material as an early warning sign (i.e., in bone implants) before the fracture collapse actually happens.

A Preliminary Study on the Toxic Combustion Products Testing of Polymers Used in High-Pressure Oxygen Systems

NASA Technical Reports Server (NTRS)

Hshieh, Fu-Yu; Beeson, Harold D.

2004-01-01

One likely cause of polymer ignition in a high-pressure oxygen system is adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative _ pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper reports the preliminary results of toxic combustion product testing of selected polymers in a pneumatic-impact test system. Five polymers commonly used in high-pressure oxygen systems, Nylon 6/6, polychlorotrifluoroethylene (CTFE), polytetrafluoroethylene (PTFE), fluoroelastomer (Viton(TradeMark) A), and nitrile rubber (Buna N), were tested in a pneumatic-impact test system at 2500- or 3500-psia oxygen pressure. The polymers were ignited and burned, then combustion products were collected in a stainless-steel sample bottle and analyzed by GC/MS/IRD, GC/FID, and GC/Methanizer/FID. The results of adiabatic-compression tests show that combustion of hydrocarbon polymers, nitrogen-containing polymers, and halogenated polymers in high-pressure oxygen systems are relatively complete. Toxicity of the combustion product gas is presumably much lower than the combustion product gas generated from ambient-pressure oxygen (or air) environments. The NASA-Lewis equilibrium code was used to determine the composition of combustion product gas generated from a simulated, adiabatic-compression test of nine polymers. The results are presented and discussed.

Experimental Study of Shock Generated Compressible Vortex Ring

NASA Astrophysics Data System (ADS)

Das, Debopam; Arakeri, Jaywant H.; Krothapalli, Anjaneyulu

2000-11-01

Formation of a compressible vortex ring and generation of sound associated with it is studied experimentally. Impulse of a shock wave is used to generate a vortex ring from the open end of a shock-tube. Vortex ring formation process has been studied in details using particle image Velocimetry (PIV). As the shock wave exits the tube it diffracts and expands. A circular vortex sheet forms at the edge and rolls up into a vortex ring. Far field microphone measurement shows that the acoustic pressure consists of a spike due to shock wave followed by a low frequency pressure wave of decaying nature, superimposed with high frequency pressure wave. Acoustic waves consist of waves due to expansion, waves formed in the tube during diaphragm breakage and waves associated with the vortex ring and shear-layer vortices. Unsteady evolution of the vortex ring and shear-layer vortices in the jet behind the ring is studied by measuring the velocity field using PIV. Corresponding vorticity field, circulation around the vortex core and growth rate of the vortex core is calculated from the measured velocity field. The velocity field in a compressible vortex ring differs from that of an incompressible ring due to the contribution from both shock and vortex ring.

Passage of a shock wave through inhomogeneous media and its impact on gas-bubble deformation.

PubMed

Nowakowski, A F; Ballil, A; Nicolleau, F C G A

2015-08-01

The paper investigates shock-induced vortical flows within inhomogeneous media of nonuniform thermodynamic properties. Numerical simulations are performed using a Eulerian type mathematical model for compressible multicomponent flow problems. The model, which accounts for pressure nonequilibrium and applies different equations of state for individual flow components, shows excellent capabilities for the resolution of interfaces separating compressible fluids as well as for capturing the baroclinic source of vorticity generation. The developed finite volume Godunov type computational approach is equipped with an approximate Riemann solver for calculating fluxes and handles numerically diffused zones at flow component interfaces. The computations are performed for various initial conditions and are compared with available experimental data. The initial conditions promoting a shock-bubble interaction process include weak to high planar shock waves with a Mach number ranging from 1.2 to 3 and isolated cylindrical bubble inhomogeneities of helium, argon, nitrogen, krypton, and sulphur hexafluoride. The numerical results reveal the characteristic features of the evolving flow topology. The impulsively generated flow perturbations are dominated by the reflection and refraction of the shock, the compression, and acceleration as well as the vorticity generation within the medium. The study is further extended to investigate the influence of the ratio of the heat capacities on the interface deformation.

Contribution of actin filaments to the global compressive properties of fibroblasts.

PubMed

Ujihara, Yoshihiro; Nakamura, Masanori; Miyazaki, Hiroshi; Wada, Shigeo

2012-10-01

Actin filaments are often regarded as tension-bearing components. Here, we examined the effects of actin filaments on global compressive properties of cells experimentally and numerically. Fibroblasts were harvested from the patellar tendon of a mature Japanese white rabbit and treated with cytochalasin D to depolymerize the actin filaments. Intact cells and cells with disrupted actin filaments were subjected to the compressive tests. Each floating cell was held between the cantilever and compressive plates and compressed by moving the compressive plate with a linear actuator to obtain a load-deformation curve under quasi-static conditions. The experimental results demonstrated that the initial stiffness of a cell with disrupted actin filaments decreased by 51%. After the experiments, we simulated the compressive test of cells with/without bundles of actin filaments. A bundle of actin filaments was modeled as a tension-bearing component that generates a force based on Hooke's law only when it was elongated. By contrast, if it was shortened, it was assumed to exert no force. The computational results revealed that the alignment of bundles of actin filaments significantly affected the cell stiffness. In addition, the passive reorientation of bundles of actin filaments perpendicular to the compression induced an increase in the resistance to the vertical elongation of a cell and thereby increased the cell stiffness. These results clearly indicated that bundles of actin filaments contribute to the compressive properties of a cell, even if they are tension-bearing components. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nonpainful wide-area compression inhibits experimental pain

PubMed Central

Honigman, Liat; Bar-Bachar, Ofrit; Yarnitsky, David; Sprecher, Elliot; Granovsky, Yelena

2016-01-01

Abstract Compression therapy, a well-recognized treatment for lymphoedema and venous disorders, pressurizes limbs and generates massive non-noxious afferent sensory barrages. The aim of this study was to study whether such afferent activity has an analgesic effect when applied on the lower limbs, hypothesizing that larger compression areas will induce stronger analgesic effects, and whether this effect correlates with conditioned pain modulation (CPM). Thirty young healthy subjects received painful heat and pressure stimuli (47°C for 30 seconds, forearm; 300 kPa for 15 seconds, wrist) before and during 3 compression protocols of either SMALL (up to ankles), MEDIUM (up to knees), or LARGE (up to hips) compression areas. Conditioned pain modulation (heat pain conditioned by noxious cold water) was tested before and after each compression protocol. The LARGE protocol induced more analgesia for heat than the SMALL protocol (P < 0.001). The analgesic effect interacted with gender (P = 0.015). The LARGE protocol was more efficient for females, whereas the MEDIUM protocol was more efficient for males. Pressure pain was reduced by all protocols (P < 0.001) with no differences between protocols and no gender effect. Conditioned pain modulation was more efficient than the compression-induced analgesia. For the LARGE protocol, precompression CPM efficiency positively correlated with compression-induced analgesia. Large body area compression exerts an area-dependent analgesic effect on experimental pain stimuli. The observed correlation with pain inhibition in response to robust non-noxious sensory stimulation may suggest that compression therapy shares similar mechanisms with inhibitory pain modulation assessed through CPM. PMID:27152691

Compression techniques in tele-radiology

NASA Astrophysics Data System (ADS)

Lu, Tianyu; Xiong, Zixiang; Yun, David Y.

1999-10-01

This paper describes a prototype telemedicine system for remote 3D radiation treatment planning. Due to voluminous medical image data and image streams generated in interactive frame rate involved in the application, the importance of deploying adjustable lossy to lossless compression techniques is emphasized in order to achieve acceptable performance via various kinds of communication networks. In particular, the compression of the data substantially reduces the transmission time and therefore allows large-scale radiation distribution simulation and interactive volume visualization using remote supercomputing resources in a timely fashion. The compression algorithms currently used in the software we developed are JPEG and H.263 lossy methods and Lempel-Ziv (LZ77) lossless methods. Both objective and subjective assessment of the effect of lossy compression methods on the volume data are conducted. Favorable results are obtained showing that substantial compression ratio is achievable within distortion tolerance. From our experience, we conclude that 30dB (PSNR) is about the lower bound to achieve acceptable quality when applying lossy compression to anatomy volume data (e.g. CT). For computer simulated data, much higher PSNR (up to 100dB) is expectable. This work not only introduces such novel approach for delivering medical services that will have significant impact on the existing cooperative image-based services, but also provides a platform for the physicians to assess the effects of lossy compression techniques on the diagnostic and aesthetic appearance of medical imaging.

A mesh regeneration method using quadrilateral and triangular elements for compressible flows

NASA Technical Reports Server (NTRS)

Vemaganti, G. R.; Thornton, E. A.

1989-01-01

An adaptive remeshing method using both triangular and quadrilateral elements suitable for high-speed viscous flows is presented. For inviscid flows, the method generates completely unstructured meshes. For viscous flows, structured meshes are generated for boundary layers, and unstructured meshes are generated for inviscid flow regions. Examples of inviscid and viscous adaptations for high-speed flows are presented.

Vector Quantization Algorithm Based on Associative Memories

NASA Astrophysics Data System (ADS)

Guzmán, Enrique; Pogrebnyak, Oleksiy; Yáñez, Cornelio; Manrique, Pablo

This paper presents a vector quantization algorithm for image compression based on extended associative memories. The proposed algorithm is divided in two stages. First, an associative network is generated applying the learning phase of the extended associative memories between a codebook generated by the LBG algorithm and a training set. This associative network is named EAM-codebook and represents a new codebook which is used in the next stage. The EAM-codebook establishes a relation between training set and the LBG codebook. Second, the vector quantization process is performed by means of the recalling stage of EAM using as associative memory the EAM-codebook. This process generates a set of the class indices to which each input vector belongs. With respect to the LBG algorithm, the main advantages offered by the proposed algorithm is high processing speed and low demand of resources (system memory); results of image compression and quality are presented.

Longitudinal dynamics of twin electron bunches in the Linac Coherent Light Source

DOE PAGES

Zhang, Zhen; Ding, Yuantao; Marinelli, Agostino; ...

2015-03-02

The recent development of two-color x-ray free-electron lasers, as well as the successful demonstration of high-gradient witness bunch acceleration in a plasma, have generated strong interest in electron bunch trains, where two or more electron bunches are generated, accelerated and compressed in the same accelerating bucket. In this paper we give a detailed analysis of a twin-bunch technique in a high-energy linac. This method allows the generation of two electron bunches with high peak current and independent control of time delay and energy separation. We find that the wakefields in the accelerator structures play an important role in the twin-bunchmore » compression, and through analysis show that they can be used to extend the available time delay range. As a result, based on the theoretical model and simulations we propose several methods to achieve larger time delay.« less

Transfer Error and Correction Approach in Mobile Network

NASA Astrophysics Data System (ADS)

Xiao-kai, Wu; Yong-jin, Shi; Da-jin, Chen; Bing-he, Ma; Qi-li, Zhou

With the development of information technology and social progress, human demand for information has become increasingly diverse, wherever and whenever people want to be able to easily, quickly and flexibly via voice, data, images and video and other means to communicate. Visual information to the people direct and vivid image, image / video transmission also been widespread attention. Although the third generation mobile communication systems and the emergence and rapid development of IP networks, making video communications is becoming the main business of the wireless communications, however, the actual wireless and IP channel will lead to error generation, such as: wireless channel multi- fading channels generated error and blocking IP packet loss and so on. Due to channel bandwidth limitations, the video communication compression coding of data is often beyond the data, and compress data after the error is very sensitive to error conditions caused a serious decline in image quality.

Potential Flow Model for Compressible Stratified Rayleigh-Taylor Instability

NASA Astrophysics Data System (ADS)

Rydquist, Grant; Reckinger, Scott; Owkes, Mark; Wieland, Scott

2017-11-01

The Rayleigh-Taylor Instability (RTI) is an instability that occurs when a heavy fluid lies on top of a lighter fluid in a gravitational field, or a gravity-like acceleration. It occurs in many fluid flows of a highly compressive nature. In this study potential flow analysis (PFA) is used to model the early stages of RTI growth for compressible fluids. In the localized region near the bubble tip, the effects of vorticity are negligible, so PFA is applicable, as opposed to later stages where the induced velocity due to vortices generated from the growth of the instability dominate the flow. The incompressible PFA is extended for compressibility effects by applying the growth rate and the associated perturbation spatial decay from compressible linear stability theory. The PFA model predicts theoretical values for a bubble terminal velocity for single-mode compressible RTI, dependent upon the Atwood (A) and Mach (M) numbers, which is a parameter that measures both the strength of the stratification and intrinsic compressibility. The theoretical bubble terminal velocities are compared against numerical simulations. The PFA model correctly predicts the M dependence at high A, but the model must be further extended to include additional physics to capture the behavior at low A. Undergraduate Scholars Program - Montana State University.

Reevaluation of JPEG image compression to digitalized gastrointestinal endoscopic color images: a pilot study

NASA Astrophysics Data System (ADS)

Kim, Christopher Y.

1999-05-01

Endoscopic images p lay an important role in describing many gastrointestinal (GI) disorders. The field of radiology has been on the leading edge of creating, archiving and transmitting digital images. With the advent of digital videoendoscopy, endoscopists now have the ability to generate images for storage and transmission. X-rays can be compressed 30-40X without appreciable decline in quality. We reported results of a pilot study using JPEG compression of 24-bit color endoscopic images. For that study, the result indicated that adequate compression ratios vary according to the lesion and that images could be compressed to between 31- and 99-fold smaller than the original size without an appreciable decline in quality. The purpose of this study was to expand upon the methodology of the previous sty with an eye towards application for the WWW, a medium which would expand both clinical and educational purposes of color medical imags. The results indicate that endoscopists are able to tolerate very significant compression of endoscopic images without loss of clinical image quality. This finding suggests that even 1 MB color images can be compressed to well under 30KB, which is considered a maximal tolerable image size for downloading on the WWW.

Fuzzy Relational Compression Applied on Feature Vectors for Infant Cry Recognition

NASA Astrophysics Data System (ADS)

Reyes-Galaviz, Orion Fausto; Reyes-García, Carlos Alberto

Data compression is always advisable when it comes to handling and processing information quickly and efficiently. There are two main problems that need to be solved when it comes to handling data; store information in smaller spaces and processes it in the shortest possible time. When it comes to infant cry analysis (ICA), there is always the need to construct large sound repositories from crying babies. Samples that have to be analyzed and be used to train and test pattern recognition algorithms; making this a time consuming task when working with uncompressed feature vectors. In this work, we show a simple, but efficient, method that uses Fuzzy Relational Product (FRP) to compresses the information inside a feature vector, building with this a compressed matrix that will help us recognize two kinds of pathologies in infants; Asphyxia and Deafness. We describe the sound analysis, which consists on the extraction of Mel Frequency Cepstral Coefficients that generate vectors which will later be compressed by using FRP. There is also a description of the infant cry database used in this work, along with the training and testing of a Time Delay Neural Network with the compressed features, which shows a performance of 96.44% with our proposed feature vector compression.

Adaptive sampler

DOEpatents

Watson, B.L.; Aeby, I.

1980-08-26

An adaptive data compression device for compressing data is described. The device has a frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

Compressed air energy storage system

DOEpatents

Ahrens, F.W.; Kartsounes, G.T.

An internal combustion reciprocating engine is operable as a compressor during slack demand periods utilizing excess power from a power grid to charge air into an air storage reservoir and as an expander during peak demand periods to feed power into the power grid utilizing air obtained from the air storage reservoir together with combustion reciprocating engine is operated at high pressure and a low pressure turbine and compressor are also employed for air compression and power generation.

Computational Simulation of Breast Compression Based on Segmented Breast and Fibroglandular Tissues on Magnetic Resonance Images

PubMed Central

Shih, Tzu-Ching; Chen, Jeon-Hor; Liu, Dongxu; Nie, Ke; Sun, Lizhi; Lin, Muqing; Chang, Daniel; Nalcioglu, Orhan; Su, Min-Ying

2010-01-01

This study presents a finite element based computational model to simulate the three-dimensional deformation of the breast and the fibroglandular tissues under compression. The simulation was based on 3D MR images of the breast, and the craniocaudal and mediolateral oblique compression as used in mammography was applied. The geometry of whole breast and the segmented fibroglandular tissues within the breast were reconstructed using triangular meshes by using the Avizo® 6.0 software package. Due to the large deformation in breast compression, a finite element model was used to simulate the non-linear elastic tissue deformation under compression, using the MSC.Marc® software package. The model was tested in 4 cases. The results showed a higher displacement along the compression direction compared to the other two directions. The compressed breast thickness in these 4 cases at 60% compression ratio was in the range of 5-7 cm, which is the typical range of thickness in mammography. The projection of the fibroglandular tissue mesh at 60% compression ratio was compared to the corresponding mammograms of two women, and they demonstrated spatially matched distributions. However, since the compression was based on MRI, which has much coarser spatial resolution than the in-plane resolution of mammography, this method is unlikely to generate a synthetic mammogram close to the clinical quality. Whether this model may be used to understand the technical factors that may impact the variations in breast density measurements needs further investigation. Since this method can be applied to simulate compression of the breast at different views and different compression levels, another possible application is to provide a tool for comparing breast images acquired using different imaging modalities – such as MRI, mammography, whole breast ultrasound, and molecular imaging – that are performed using different body positions and different compression conditions. PMID:20601773

Computational simulation of breast compression based on segmented breast and fibroglandular tissues on magnetic resonance images.

PubMed

Shih, Tzu-Ching; Chen, Jeon-Hor; Liu, Dongxu; Nie, Ke; Sun, Lizhi; Lin, Muqing; Chang, Daniel; Nalcioglu, Orhan; Su, Min-Ying

2010-07-21

This study presents a finite element-based computational model to simulate the three-dimensional deformation of a breast and fibroglandular tissues under compression. The simulation was based on 3D MR images of the breast, and craniocaudal and mediolateral oblique compression, as used in mammography, was applied. The geometry of the whole breast and the segmented fibroglandular tissues within the breast were reconstructed using triangular meshes by using the Avizo 6.0 software package. Due to the large deformation in breast compression, a finite element model was used to simulate the nonlinear elastic tissue deformation under compression, using the MSC.Marc software package. The model was tested in four cases. The results showed a higher displacement along the compression direction compared to the other two directions. The compressed breast thickness in these four cases at a compression ratio of 60% was in the range of 5-7 cm, which is a typical range of thickness in mammography. The projection of the fibroglandular tissue mesh at a compression ratio of 60% was compared to the corresponding mammograms of two women, and they demonstrated spatially matched distributions. However, since the compression was based on magnetic resonance imaging (MRI), which has much coarser spatial resolution than the in-plane resolution of mammography, this method is unlikely to generate a synthetic mammogram close to the clinical quality. Whether this model may be used to understand the technical factors that may impact the variations in breast density needs further investigation. Since this method can be applied to simulate compression of the breast at different views and different compression levels, another possible application is to provide a tool for comparing breast images acquired using different imaging modalities--such as MRI, mammography, whole breast ultrasound and molecular imaging--that are performed using different body positions and under different compression conditions.

Dynamic response and residual stress fields of Ti6Al4V alloy under shock wave induced by laser shock peening

NASA Astrophysics Data System (ADS)

Sun, Rujian; Li, Liuhe; Zhu, Ying; Zhang, Lixin; Guo, Wei; Peng, Peng; Li, Bo; Guo, Chao; Liu, Lei; Che, Zhigang; Li, Weidong; Sun, Jianfei; Qiao, Hongchao

2017-09-01

Laser shock peening (LSP), an innovative surface treatment technique, generates compressive residual stress on the surface of metallic components to improve their fatigue performance, wear resistance and corrosion resistance. To illustrate the dynamic response during LSP and residual stress fields after LSP, this study conducted FEM simulations of LSP in a Ti6Al4V alloy. Results showed that when power density was 7 GW cm-2, a plastic deformation occurred at 10 ns during LSP and increased until the shock pressure decayed below the dynamic yield strength of Ti6Al4V after 60 ns. A maximum tensile region appeared beneath the surface at around 240 ns, forming a compressive-tensile-compressive stress sandwich structure with a thickness of 98, 1020 and 606 μm for each layer. After the model became stabilized, the value of the surface residual compressive stress was 564 MPa at the laser spot center. Higher value of residual stress across the surface and thicker compressive residual stress layers were achieved by increasing laser power density, impact times and spot sizes during LSP. A ‘Residual stress hole’ occurred with a high laser power density of 9 GW cm-2 when laser pulse duration was 10 ns, or with a long laser pulse duration of 20 ns when laser power density was 7 GW cm-2 for Ti6Al4V. This phenomenon occurred because of the permanent reverse plastic deformation generated at laser spot center.

Influence of Eco-Friendly Mineral Additives on Early Age Compressive Strength and Temperature Development of High-Performance Concrete

NASA Astrophysics Data System (ADS)

Kaszynska, Maria; Skibicki, Szymon

2017-12-01

High-performance concrete (HPC) which contains increased amount of both higher grade cement and pozzolanic additives generates more hydration heat than the ordinary concrete. Prolonged periods of elevated temperature influence the rate of hydration process in result affecting the development of early-age strength and subsequent mechanical properties. The purpose of the presented research is to determine the relationship between the kinetics of the heat generation process and the compressive strength of early-age high performance concrete. All mixes were based on the Portland Cement CEM I 52.5 with between 7.5% to 15% of the cement mass replaced by the silica fume or metakaolin. Two characteristic for HPC water/binder ratios of w/b = 0.2 and w/b = 0.3 were chosen. A superplasticizer was used to maintain a 20-50 mm slump. Compressive strength was determined at 8h, 24h, 3, 7 and 28 days on 10x10x10 cm specimens that were cured in a calorimeter in a constant temperature of T = 20°C. The temperature inside the concrete was monitored continuously for 7 days. The study determined that the early-age strength (t<24h) of concrete with reactive mineral additives is lower than concrete without them. This is clearly visible for concretes with metakaolin which had the lowest compressive strength in early stages of hardening. The amount of the superplasticizer significantly influenced the early-age compressive strength of concrete. Concretes with additives reached the maximum temperature later than the concretes without them.

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

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

McGonegle, David, E-mail: d.mcgonegle1@physics.ox.ac.uk; Wark, Justin S.; Higginbotham, Andrew

2015-08-14

A growing number of shock compression experiments, especially those involving laser compression, are taking advantage of in situ x-ray diffraction as a tool to interrogate structure and microstructure evolution. Although these experiments are becoming increasingly sophisticated, there has been little work on exploiting the textured nature of polycrystalline targets to gain information on sample response. Here, we describe how to generate simulated x-ray diffraction patterns from materials with an arbitrary texture function subject to a general deformation gradient. We will present simulations of Debye-Scherrer x-ray diffraction from highly textured polycrystalline targets that have been subjected to uniaxial compression, as maymore » occur under planar shock conditions. In particular, we study samples with a fibre texture, and find that the azimuthal dependence of the diffraction patterns contains information that, in principle, affords discrimination between a number of similar shock-deformation mechanisms. For certain cases, we compare our method with results obtained by taking the Fourier transform of the atomic positions calculated by classical molecular dynamics simulations. Illustrative results are presented for the shock-induced α–ϵ phase transition in iron, the α–ω transition in titanium and deformation due to twinning in tantalum that is initially preferentially textured along [001] and [011]. The simulations are relevant to experiments that can now be performed using 4th generation light sources, where single-shot x-ray diffraction patterns from crystals compressed via laser-ablation can be obtained on timescales shorter than a phonon period.« less

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

DOE PAGES

McGonegle, David; Milathianaki, Despina; Remington, Bruce A.; ...

2015-08-11

A growing number of shock compression experiments, especially those involving laser compression, are taking advantage of in situ x-ray diffraction as a tool to interrogate structure and microstructure evolution. Although these experiments are becoming increasingly sophisticated, there has been little work on exploiting the textured nature of polycrystalline targets to gain information on sample response. Here, we describe how to generate simulated x-ray diffraction patterns from materials with an arbitrary texture function subject to a general deformation gradient. We will present simulations of Debye-Scherrer x-ray diffraction from highly textured polycrystalline targets that have been subjected to uniaxial compression, as maymore » occur under planar shock conditions. In particular, we study samples with a fibre texture, and find that the azimuthal dependence of the diffraction patterns contains information that, in principle, affords discrimination between a number of similar shock-deformation mechanisms. For certain cases, we compare our method with results obtained by taking the Fourier transform of the atomic positions calculated by classical molecular dynamics simulations. Illustrative results are presented for the shock-induced α–ϵ phase transition in iron, the α–ω transition in titanium and deformation due to twinning in tantalum that is initially preferentially textured along [001] and [011]. In conclusion, the simulations are relevant to experiments that can now be performed using 4th generation light sources, where single-shot x-ray diffraction patterns from crystals compressed via laser-ablation can be obtained on timescales shorter than a phonon period.« less

Study of adaptive methods for data compression of scanner data

NASA Technical Reports Server (NTRS)

1977-01-01

The performance of adaptive image compression techniques and the applicability of a variety of techniques to the various steps in the data dissemination process are examined in depth. It is concluded that the bandwidth of imagery generated by scanners can be reduced without introducing significant degradation such that the data can be transmitted over an S-band channel. This corresponds to a compression ratio equivalent to 1.84 bits per pixel. It is also shown that this can be achieved using at least two fairly simple techniques with weight-power requirements well within the constraints of the LANDSAT-D satellite. These are the adaptive 2D DPCM and adaptive hybrid techniques.

Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering at flame temperatures using a second-harmonic bandwidth-compressed probe.

PubMed

Kearney, Sean P; Scoglietti, Daniel J

2013-03-15

We demonstrate an approach for picosecond probe-beam generation that enables hybrid femtosecond/picosecond pure-rotational coherent anti-Stokes Raman scattering (CARS) measurements in flames. Sum-frequency generation of bandwidth-compressed picosecond radiation from femtosecond pumps with phase-conjugate chirps provides probe pulses with energies in excess of 1 mJ that are temporally locked to the femtosecond pump/Stokes preparation. This method overcomes previous limitations on hybrid femtosecond/picosecond rotational CARS techniques, which have relied upon less efficient bandwidth-reduction processes that have generally resulted in prohibitively low probe energy for flame measurements. We provide the details of the second-harmonic approach and demonstrate the technique in near-adiabatic hydrogen/air flames.

A finite element approach for solution of the 3D Euler equations

NASA Technical Reports Server (NTRS)

Thornton, E. A.; Ramakrishnan, R.; Dechaumphai, P.

1986-01-01

Prediction of thermal deformations and stresses has prime importance in the design of the next generation of high speed flight vehicles. Aerothermal load computations for complex three-dimensional shapes necessitate development of procedures to solve the full Navier-Stokes equations. This paper details the development of a three-dimensional inviscid flow approach which can be extended for three-dimensional viscous flows. A finite element formulation, based on a Taylor series expansion in time, is employed to solve the compressible Euler equations. Model generation and results display are done using a commercially available program, PATRAN, and vectorizing strategies are incorporated to ensure computational efficiency. Sample problems are presented to demonstrate the validity of the approach for analyzing high speed compressible flows.

Laser or charged-particle-beam fusion reactor with direct electric generation by magnetic flux compression

DOEpatents

Lasche, G.P.

1983-09-29

The invention is a laser or particle-beam-driven fusion reactor system which takes maximum advantage of both the very short pulsed nature of the energy release of inertial confinement fusion (ICF) and the very small volumes within which the thermonuclear burn takes place. The pulsed nature of ICF permits dynamic direct energy conversion schemes such as magnetohydrodynamic (MHD) generation and magnetic flux compression; the small volumes permit very compact blanket geometries. By fully exploiting these characteristics of ICF, it is possible to design a fusion reactor with exceptionally high power density, high net electric efficiency, and low neutron-induced radioactivity. The invention includes a compact blanket design and method and apparatus for obtaining energy utilizing the compact blanket.

Miniature reciprocating heat pumps and engines

NASA Technical Reports Server (NTRS)

Thiesen, Jack H. (Inventor); Mohling, Robert A. (Inventor); Willen, Gary S. (Inventor)

2003-01-01

The present invention discloses a miniature thermodynamic device that can be constructed using standard micro-fabrication techniques. The device can be used to provide cooling, generate power, compress gases, pump fluids and reduce pressure below ambient (operate as a vacuum pump). Embodiments of the invention relating to the production of a cooling effect and the generation of electrical power, change the thermodynamic state of the system by extracting energy from a pressurized fluid. Energy extraction is attained using an expansion process, which is as nearly isentropic as possible for the appropriately chosen fluid. An isentropic expansion occurs when a compressed gas does work to expand, and in the disclosed embodiments, the gas does work by overcoming either an electrostatic or a magnetic force.

A compact targeted drug delivery mechanism for a next generation wireless capsule endoscope.

PubMed

Woods, Stephen P; Constandinou, Timothy G

2016-01-01

This paper reports a novel medication release and delivery mechanism as part of a next generation wireless capsule endoscope (WCE) for targeted drug delivery. This subsystem occupies a volume of only 17.9mm 3 for the purpose of delivering a 1 ml payload to a target site of interest in the small intestinal tract. An in-depth analysis of the method employed to release and deliver the medication is described and a series of experiments is presented which validates the drug delivery system. The results show that a variable pitch conical compression spring manufactured from stainless steel can deliver 0.59 N when it is fully compressed and that this would be sufficient force to deliver the onboard medication.

Partial oxidation power plant with reheating and method thereof

DOEpatents

Newby, R.A.; Yang, W.C.; Bannister, R.L.

1999-08-10

A system and method are disclosed for generating power having an air compression/partial oxidation system, a turbine, and a primary combustion system. The air compression/partial oxidation system receives a first air stream and a fuel stream and produces a first partially oxidized fuel stream and a first compressed air stream therefrom. The turbine expands the first partially oxidized fuel stream while being cooled by the first compressed air stream to produce a heated air stream. The heated air stream is injected into the expanding first partially oxidized fuel stream, thereby reheating it in the turbine. A second partially oxidized fuel stream is emitted from the turbine. The primary combustion system receives said second partially oxidized fuel stream and a second air stream, combusts said second partially oxidized fuel stream, and produces rotating shaft power and an emission stream therefrom. 2 figs.

Biomechanical evaluation of a new composite bioresorbable screw.

PubMed

Bailey, C A; Kuiper, J H; Kelly, C P

2006-04-01

A new bioresorbable composite cannulated screw has been developed for small bone fracture fixation. The LG ("Little Grafter") screw is manufactured from Biosteon, which is a composite of poly L-lactic acid and hydroxyapatite. This study aimed to compare interfragmentary compression generated by this new screw with conventional metal screws commonly used in scaphoid fracture fixation. Four small metallic screws were compared with the LG screw, using a bone model produced from rigid polyurethane foam. The screws included the Acutrak, Asnis III, Herbert and Herbert-Whipple screws. The mean maximum compression forces for the LG screw, the Asnis and the Acutrak were comparable (LG 32.3 N, Asnis 32.8 N, Acutrak 38.3 N), whereas those using the Herbert and the Herbert-Whipple screw were significantly lower (Herbert 21.8 N, Herbert-Whipple 19.9 N). The bioresorbable LG screw has been shown to have good compressive properties compared to commonly used small bone fragment compression screws.

Ultra-Flexibility and Unusual Electronic, Magnetic and Chemical Properties of Waved Graphenes and Nanoribbons

PubMed Central

Pan, Hui; Chen, Bin

2014-01-01

Two-dimensional materials have attracted increasing attention because of their particular properties and potential applications in next-generation nanodevices. In this work, we investigate the physical and chemical properties of waved graphenes/nanoribbons based on first-principles calculations. We show that waved graphenes are compressible up to a strain of 50% and ultra-flexible because of the vanishing in-plane stiffness. The conductivity of waved graphenes is reduced due to charge decoupling under high compression. Our analysis of pyramidalization angles predicts that the chemistry of waved graphenes can be easily controlled by modulating local curvatures. We further demonstrate that band gaps of armchair waved graphene nanoribbons decrease with the increase of compression if they are asymmetrical in geometry, while increase if symmetrical. For waved zigzag nanoribbons, their anti-ferromagnetic states are strongly enhanced by increasing compression. The versatile functions of waved graphenes enable their applications in multi-functional nanodevices and sensors. PMID:24569444

Wave transmission through silicone foam pads in a compression Kolsky bar apparatus. Comparisons between simulations and measurements.

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

Corona, Edmundo; Song, Bo

This memo concerns the transmission of mechanical signals through silicone foam pads in a compression Kolsky bar set-up. The results of numerical simulations for four levels of pad pre-compression and two striker velocities were compared directly to test measurements to assess the delity of the simulations. The nite element model simulated the Kolsky tests in their entirety and used the hyperelastic `hyperfoam' model for the silicone foam pads. Calibration of the hyperfoam model was deduced from quasi-static compression data. It was necessary, however, to augment the material model by adding sti ness proportional damping in order to generate results thatmore » resembled the experimental measurements. Based on the results presented here, it is important to account for the dynamic behavior of polymeric foams in numerical simulations that involve high loading rates.« less

Optimization of the segmented method for optical compression and multiplexing system

NASA Astrophysics Data System (ADS)

Al Falou, Ayman

2002-05-01

Because of the constant increasing demands of images exchange, and despite the ever increasing bandwidth of the networks, compression and multiplexing of images is becoming inseparable from their generation and display. For high resolution real time motion pictures, electronic performing of compression requires complex and time-consuming processing units. On the contrary, by its inherent bi-dimensional character, coherent optics is well fitted to perform such processes that are basically bi-dimensional data handling in the Fourier domain. Additionally, the main limiting factor that was the maximum frame rate is vanishing because of the recent improvement of spatial light modulator technology. The purpose of this communication is to benefit from recent optical correlation algorithms. The segmented filtering used to store multi-references in a given space bandwidth product optical filter can be applied to networks to compress and multiplex images in a given bandwidth channel.

Atomic Oxygen Exposure of Polyimide Foam for International Space Station Solar Array Wing Blanket Box

NASA Technical Reports Server (NTRS)

Finckenor, M. M.; Albyn, K. C.; Watts, E. W.

2006-01-01

Onorbit photos of the International Space Station (ISS) solar array blanket box foam pad assembly indicate degradation of the Kapton film covering the foam, leading to atomic oxygen (AO) exposure of the foam. The purpose of this test was to determine the magnitude of particulate generation caused by low-Earth orbital environment exposure of the foam and also by compression of the foam during solar array wing retraction. The polyimide foam used in the ISS solar array wing blanket box assembly is susceptible to significant AO erosion. The foam sample in this test lost one-third of its mass after exposure to the equivalent of 22 mo onorbit. Some particulate was generated by exposure to simulated orbital conditions and the simulated solar array retraction (compression test). However, onorbit, these particles would also be eroded by AO. The captured particles were generally <1 mm, and the particles shaken free of the sample had a maximum size of 4 mm. The foam sample maintained integrity after a compression load of 2.5 psi.

An efficient user-oriented method for calculating compressible flow in an about three-dimensional inlets. [panel method

NASA Technical Reports Server (NTRS)

Hess, J. L.; Mack, D. P.; Stockman, N. O.

1979-01-01

A panel method is used to calculate incompressible flow about arbitrary three-dimensional inlets with or without centerbodies for four fundamental flow conditions: unit onset flows parallel to each of the coordinate axes plus static operation. The computing time is scarcely longer than for a single solution. A linear superposition of these solutions quite rigorously gives incompressible flow about the inlet for any angle of attack, angle of yaw, and mass flow rate. Compressibility is accounted for by applying a well-proven correction to the incompressible flow. Since the computing times for the combination and the compressibility correction are small, flows at a large number of inlet operating conditions are obtained rather cheaply. Geometric input is aided by an automatic generating program. A number of graphical output features are provided to aid the user, including surface streamline tracing and automatic generation of curves of curves of constant pressure, Mach number, and flow inclination at selected inlet cross sections. The inlet method and use of the program are described. Illustrative results are presented.

Radial distribution of compressive waves in the solar corona revealed by Akatsuki radio occultation observations

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

Miyamoto, Mayu; Imamura, Takeshi; Ando, Hiroki

Radial variations of the amplitude and the energy flux of compressive waves in the solar corona were explored for the first time using a spacecraft radio occultation technique. By applying wavelet analysis to the frequency time series taken at heliocentric distances of 1.5-20.5 R{sub S} (solar radii), quasi-periodic density disturbances were detected at almost all distances. The period ranges from 100 to 2000 s. The amplitude of the fractional density fluctuation increases with distance and reaches ∼30% around 5 R{sub S} , implying that nonlinearity of the wave field is potentially important. We further estimate the wave energy flux onmore » the assumption that the observed periodical fluctuations are manifestations of acoustic waves. The energy flux increases with distance below ∼6 R{sub S} and seems to saturate above this height, suggesting that the acoustic waves do not propagate from the low corona but are generated in the extended corona, probably through nonlinear dissipation of Alfvén waves. The compressive waves should eventually dissipate through shock generation to heat the corona.« less

Dynamic Behaviors of Materials under Ramp Wave Loading on Compact Pulsed Power Generators

NASA Astrophysics Data System (ADS)

Zhao, Jianheng; Luo, Binqiang; Wang, Guiji; Chong, Tao; Tan, Fuli; Liu, Cangli; Sun, Chengwei

The technique using intense current to produce magnetic pressure provides a unique way to compress matter near isentrope to high density without obvious temperature increment, which is characterized as ramp wave loading, and firstly developed by Sandia in 1998. Firstly recent advances on compact pulsed power generators developed in our laboratory, such as CQ-4, CQ-3-MMAF and CQ-7 devices, are simply introduced here, which devoted to ramp wave loading from 50GPa to 200 GPa, and to ultrahigh-velocity flyer launching up to 30 km/s. And then, we show our progress in data processing methods and experiments of isentropic compression conducted on these devices mentioned above. The suitability of Gruneisen EOS and Vinet EOS are validated by isentropic experiments of tantalum, and the parameters of SCG constitutive equation of aluminum and copper are modified to give better prediction under isentropic compression. Phase transition of bismuth and tin are investigated under different initial temperatures, parameters of Helmholtz free energy and characteristic relaxation time in kinetic phase transition equation are calibrated. Supported by NNSF of China under Contract No.11327803 and 11176002

Power supply

DOEpatents

Hart, Edward J.; Leeman, James E.; MacDougall, Hugh R.; Marron, John J.; Smith, Calvin C.

1976-01-01

An electric power supply employs a striking means to initiate ferroelectric elements which provide electrical energy output which subsequently initiates an explosive charge which initiates a second ferroelectric current generator to deliver current to the coil of a magnetic field current generator, creating a magnetic field around the coil. Continued detonation effects compression of the magnetic field and subsequent generation and delivery of a large output current to appropriate output loads.

Implementation of a compressive sampling scheme for wireless sensors to achieve energy efficiency in a structural health monitoring system

NASA Astrophysics Data System (ADS)

O'Connor, Sean M.; Lynch, Jerome P.; Gilbert, Anna C.

2013-04-01

Wireless sensors have emerged to offer low-cost sensors with impressive functionality (e.g., data acquisition, computing, and communication) and modular installations. Such advantages enable higher nodal densities than tethered systems resulting in increased spatial resolution of the monitoring system. However, high nodal density comes at a cost as huge amounts of data are generated, weighing heavy on power sources, transmission bandwidth, and data management requirements, often making data compression necessary. The traditional compression paradigm consists of high rate (>Nyquist) uniform sampling and storage of the entire target signal followed by some desired compression scheme prior to transmission. The recently proposed compressed sensing (CS) framework combines the acquisition and compression stage together, thus removing the need for storage and operation of the full target signal prior to transmission. The effectiveness of the CS approach hinges on the presence of a sparse representation of the target signal in a known basis, similarly exploited by several traditional compressive sensing applications today (e.g., imaging, MRI). Field implementations of CS schemes in wireless SHM systems have been challenging due to the lack of commercially available sensing units capable of sampling methods (e.g., random) consistent with the compressed sensing framework, often moving evaluation of CS techniques to simulation and post-processing. The research presented here describes implementation of a CS sampling scheme to the Narada wireless sensing node and the energy efficiencies observed in the deployed sensors. Of interest in this study is the compressibility of acceleration response signals collected from a multi-girder steel-concrete composite bridge. The study shows the benefit of CS in reducing data requirements while ensuring data analysis on compressed data remain accurate.

A gigawatt level repetitive rate adjustable magnetic pulse compressor.

PubMed

Li, Song; Gao, Jing-Ming; Yang, Han-Wu; Qian, Bao-Liang; Li, Ze-Xin

2015-08-01

In this paper, a gigawatt level repetitive rate adjustable magnetic pulse compressor is investigated both numerically and experimentally. The device has advantages of high power level, high repetitive rate achievability, and long lifetime reliability. Importantly, dominate parameters including the saturation time, the peak voltage, and even the compression ratio can be potentially adjusted continuously and reliably, which significantly expands the applicable area of the device and generators based on it. Specifically, a two-stage adjustable magnetic pulse compressor, utilized for charging the pulse forming network of a high power pulse generator, is designed with different compression ratios of 25 and 18 through an optimized design process. Equivalent circuit analysis shows that the modification of compression ratio can be achieved by just changing the turn number of the winding. At the same time, increasing inductance of the grounded inductor will decrease the peak voltage and delay the charging process. Based on these analyses, an adjustable compressor was built and studied experimentally in both the single shot mode and repetitive rate mode. Pulses with peak voltage of 60 kV and energy per pulse of 360 J were obtained in the experiment. The rise times of the pulses were compressed from 25 μs to 1 μs and from 18 μs to 1 μs, respectively, at repetitive rate of 20 Hz with good repeatability. Experimental results show reasonable agreement with analyses.

Data Assimilation by Ensemble Kalman Filter during One-Dimensional Nonlinear Consolidation in Randomly Heterogeneous Highly Compressible Aquitards

NASA Astrophysics Data System (ADS)

Zapata Norberto, B.; Morales-Casique, E.; Herrera, G. S.

2017-12-01

Severe land subsidence due to groundwater extraction may occur in multiaquifer systems where highly compressible aquitards are present. The highly compressible nature of the aquitards leads to nonlinear consolidation where the groundwater flow parameters are stress-dependent. The case is further complicated by the heterogeneity of the hydrogeologic and geotechnical properties of the aquitards. We explore the effect of realistic vertical heterogeneity of hydrogeologic and geotechnical parameters on the consolidation of highly compressible aquitards by means of 1-D Monte Carlo numerical simulations. 2000 realizations are generated for each of the following parameters: hydraulic conductivity (K), compression index (Cc) and void ratio (e). The correlation structure, the mean and the variance for each parameter were obtained from a literature review about field studies in the lacustrine sediments of Mexico City. The results indicate that among the parameters considered, random K has the largest effect on the ensemble average behavior of the system. Random K leads to the largest variance (and therefore largest uncertainty) of total settlement, groundwater flux and time to reach steady state conditions. We further propose a data assimilation scheme by means of ensemble Kalman filter to estimate the ensemble mean distribution of K, pore-pressure and total settlement. We consider the case where pore-pressure measurements are available at given time intervals. We test our approach by generating a 1-D realization of K with exponential spatial correlation, and solving the nonlinear flow and consolidation problem. These results are taken as our "true" solution. We take pore-pressure "measurements" at different times from this "true" solution. The ensemble Kalman filter method is then employed to estimate ensemble mean distribution of K, pore-pressure and total settlement based on the sequential assimilation of these pore-pressure measurements. The ensemble-mean estimates from this procedure closely approximate those from the "true" solution. This procedure can be easily extended to other random variables such as compression index and void ratio.

Three-Dimensional Inverse Transport Solver Based on Compressive Sensing Technique

NASA Astrophysics Data System (ADS)

Cheng, Yuxiong; Wu, Hongchun; Cao, Liangzhi; Zheng, Youqi

2013-09-01

According to the direct exposure measurements from flash radiographic image, a compressive sensing-based method for three-dimensional inverse transport problem is presented. The linear absorption coefficients and interface locations of objects are reconstructed directly at the same time. It is always very expensive to obtain enough measurements. With limited measurements, compressive sensing sparse reconstruction technique orthogonal matching pursuit is applied to obtain the sparse coefficients by solving an optimization problem. A three-dimensional inverse transport solver is developed based on a compressive sensing-based technique. There are three features in this solver: (1) AutoCAD is employed as a geometry preprocessor due to its powerful capacity in graphic. (2) The forward projection matrix rather than Gauss matrix is constructed by the visualization tool generator. (3) Fourier transform and Daubechies wavelet transform are adopted to convert an underdetermined system to a well-posed system in the algorithm. Simulations are performed and numerical results in pseudo-sine absorption problem, two-cube problem and two-cylinder problem when using compressive sensing-based solver agree well with the reference value.

Evaluation of Algorithms for Compressing Hyperspectral Data

NASA Technical Reports Server (NTRS)

Cook, Sid; Harsanyi, Joseph; Faber, Vance

2003-01-01

With EO-1 Hyperion in orbit NASA is showing their continued commitment to hyperspectral imaging (HSI). As HSI sensor technology continues to mature, the ever-increasing amounts of sensor data generated will result in a need for more cost effective communication and data handling systems. Lockheed Martin, with considerable experience in spacecraft design and developing special purpose onboard processors, has teamed with Applied Signal & Image Technology (ASIT), who has an extensive heritage in HSI spectral compression and Mapping Science (MSI) for JPEG 2000 spatial compression expertise, to develop a real-time and intelligent onboard processing (OBP) system to reduce HSI sensor downlink requirements. Our goal is to reduce the downlink requirement by a factor > 100, while retaining the necessary spectral and spatial fidelity of the sensor data needed to satisfy the many science, military, and intelligence goals of these systems. Our compression algorithms leverage commercial-off-the-shelf (COTS) spectral and spatial exploitation algorithms. We are currently in the process of evaluating these compression algorithms using statistical analysis and NASA scientists. We are also developing special purpose processors for executing these algorithms onboard a spacecraft.

Rapid classification of pharmaceutical ingredients with Raman spectroscopy using compressive detection strategy with PLS-DA multivariate filters.

PubMed

Cebeci Maltaş, Derya; Kwok, Kaho; Wang, Ping; Taylor, Lynne S; Ben-Amotz, Dor

2013-06-01

Identifying pharmaceutical ingredients is a routine procedure required during industrial manufacturing. Here we show that a recently developed Raman compressive detection strategy can be employed to classify various widely used pharmaceutical materials using a hybrid supervised/unsupervised strategy in which only two ingredients are used for training and yet six other ingredients can also be distinguished. More specifically, our liquid crystal spatial light modulator (LC-SLM) based compressive detection instrument is trained using only the active ingredient, tadalafil, and the excipient, lactose, but is tested using these and various other excipients; microcrystalline cellulose, magnesium stearate, titanium (IV) oxide, talc, sodium lauryl sulfate and hydroxypropyl cellulose. Partial least squares discriminant analysis (PLS-DA) is used to generate the compressive detection filters necessary for fast chemical classification. Although the filters used in this study are trained on only lactose and tadalafil, we show that all the pharmaceutical ingredients mentioned above can be differentiated and classified using PLS-DA compressive detection filters with an accumulation time of 10ms per filter. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetothermodynamics: measurements of the thermodynamic properties in a relaxed magnetohydrodynamic plasma

NASA Astrophysics Data System (ADS)

Kaur, M.; Barbano, L. J.; Suen-Lewis, E. M.; Shrock, J. E.; Light, A. D.; Schaffner, D. A.; Brown, M. B.; Woodruff, S.; Meyer, T.

2018-02-01

We have explored the thermodynamics of compressed magnetized plasmas in laboratory experiments and we call these studies `magnetothermodynamics'. The experiments are carried out in the Swarthmore Spheromak eXperiment device. In this device, a magnetized plasma source is located at one end and at the other end, a closed conducting can is installed. We generate parcels of magnetized plasma and observe their compression against the end wall of the conducting cylinder. The plasma parameters such as plasma density, temperature and magnetic field are measured during compression using HeNe laser interferometry, ion Doppler spectroscopy and a linear probe array, respectively. To identify the instances of ion heating during compression, a PV diagram is constructed using measured density, temperature and a proxy for the volume of the magnetized plasma. Different equations of state are analysed to evaluate the adiabatic nature of the compressed plasma. A three-dimensional resistive magnetohydrodynamic code (NIMROD) is employed to simulate the twisted Taylor states and shows stagnation against the end wall of the closed conducting can. The simulation results are consistent to what we observe in our experiments.

A composite generator film impregnated with cellulose nanocrystals for enhanced triboelectric performance

Treesearch

Jun Peng; Huilong Zhang; Qifeng Zheng; Craig M. Clemons; Ronald C. Sabo; Shaoqin Gong; Zhenqiang Ma; Lih-Sheng Turng

2017-01-01

A novel polydimethylsiloxane (PDMS)/cellulose nanocrystal flake (CNCF) composite triboelectric nanogenerator (CTG) using CNCFs as effective dielectrics a 10-times-enhanced triboelectric performance compared with its pure PDMS counterpart. Positive charges generated on the surface of the CNCFs during cyclic compression boosted electron transfer and induced extra charges...

Filamentation in Air with Ultrashort Mid-Infrared Pulses

DTIC Science & Technology

2011-05-09

remote sensing [11, 12], lightning guiding [13–15], supercontinuum generation ( SCG ) [16], pulse compression [17], and THz generation [18]. Although...shock) and push the pulse toward positive times [23, 24, 46, 54, 55] [see Fig. 3(a) at ζ = 0.6]. Subsequently, the pulse collapses at ζ = 0.9, and SCG

Computation of the bluff-body sound generation by a self-consistent mean flow formulation

NASA Astrophysics Data System (ADS)

Fani, A.; Citro, V.; Giannetti, F.; Auteri, F.

2018-03-01

The sound generated by the flow around a circular cylinder is numerically investigated by using a finite-element method. In particular, we study the acoustic emissions generated by the flow past the bluff body at low Mach and Reynolds numbers. We perform a global stability analysis by using the compressible linearized Navier-Stokes equations. The resulting direct global mode provides detailed information related to the underlying hydrodynamic instability and data on the acoustic field generated. In order to recover the intensity of the produced sound, we apply the self-consistent model for non-linear saturation proposed by Mantič-Lugo, Arratia, and Gallaire ["Self-consistent mean flow description of the nonlinear saturation of the vortex shedding in the cylinder wake," Phys. Rev. Lett. 113, 084501 (2014)]. The application of this model allows us to compute the amplitude of the resulting linear mode and the effects of saturation on the mode structure and acoustic field. Our results show excellent agreement with those obtained by a full compressible simulation direct numerical simulation and those derived by the application of classical acoustic analogy formulations.

Layered compression for high-precision depth data.

PubMed

Miao, Dan; Fu, Jingjing; Lu, Yan; Li, Shipeng; Chen, Chang Wen

2015-12-01

With the development of depth data acquisition technologies, access to high-precision depth with more than 8-b depths has become much easier and determining how to efficiently represent and compress high-precision depth is essential for practical depth storage and transmission systems. In this paper, we propose a layered high-precision depth compression framework based on an 8-b image/video encoder to achieve efficient compression with low complexity. Within this framework, considering the characteristics of the high-precision depth, a depth map is partitioned into two layers: 1) the most significant bits (MSBs) layer and 2) the least significant bits (LSBs) layer. The MSBs layer provides rough depth value distribution, while the LSBs layer records the details of the depth value variation. For the MSBs layer, an error-controllable pixel domain encoding scheme is proposed to exploit the data correlation of the general depth information with sharp edges and to guarantee the data format of LSBs layer is 8 b after taking the quantization error from MSBs layer. For the LSBs layer, standard 8-b image/video codec is leveraged to perform the compression. The experimental results demonstrate that the proposed coding scheme can achieve real-time depth compression with satisfactory reconstruction quality. Moreover, the compressed depth data generated from this scheme can achieve better performance in view synthesis and gesture recognition applications compared with the conventional coding schemes because of the error control algorithm.

Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition.

PubMed

Kodama, R; Norreys, P A; Mima, K; Dangor, A E; Evans, R G; Fujita, H; Kitagawa, Y; Krushelnick, K; Miyakoshi, T; Miyanaga, N; Norimatsu, T; Rose, S J; Shozaki, T; Shigemori, K; Sunahara, A; Tampo, M; Tanaka, K A; Toyama, Y; Yamanaka, T; Zepf, M

2001-08-23

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.

Large Amplitude IMF Fluctuations in Corotating Interaction Regions: Ulysses at Midlatitudes

NASA Technical Reports Server (NTRS)

Tsurutani, Bruce T.; Ho, Christian M.; Arballo, John K.; Goldstein, Bruce E.; Balogh, Andre

1995-01-01

Corotating Interaction Regions (CIRs), formed by high-speed corotating streams interacting with slow speed streams, have been examined from -20 deg to -36 deg heliolatitudes. The high-speed streams emanate from a polar coronal hole that Ulysses eventually becomes fully embedded in as it travels towards the south pole. We find that the trailing portion of the CIR, from the interface surface (IF) to the reverse shock (RS), contains both large amplitude transverse fluctuations and magnitude fluctuations. Similar fluctuations have been previously noted to exist within CIRs detected in the ecliptic plane, but their existence has not been explained. The normalized magnetic field component variances within this portion of the CIR and in the trailing high-speed stream are approximately the same, indicating that the fluctuations in the CIR are compressed Alfven waves. Mirror mode structures with lower intensities are also observed in the trailing portion of the CIR, presumably generated from a local instability driven by free energy associated with compression of the high-speed solar wind plasma. The mixture of these two modes (compressed Alfven waves and mirror modes) plus other modes generated by three wave processes (wave-shock interactions) lead to a lower Alfvenicity within the trailing portion of the CfR than in the high-speed stream proper. The results presented in this paper suggest a mechanism for generation of large amplitude B(sub z) fluctuations within CIRS. Such phenomena have been noted to be responsible for the generation of moderate geomagnetic storms during the declining phase of the solar cycle.

Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint.

PubMed

Barker, P J; Hapuarachchi, K S; Ross, J A; Sambaiew, E; Ranger, T A; Briggs, C A

2014-03-01

Biomechanical models predict that recruitment of gluteus maximus (GMax) will exert a compressive force across the sacroiliac joint (SIJ), yet this muscle requires morphologic assessment. The aims of this study were to document GMax's proximal attachments and assess their capacity to generate forces including compressive force at the SIJ. In 11 embalmed cadaver limbs, attachments of GMax crossing the SIJ were dissected and their fascicle orientation, length and attachment volume documented. The physiological cross-sectional area (PCSA) of each attachment was calculated along with its estimated maximum force at the SIJ and lumbar spine. GMax fascicles originated from the gluteus medius fascia, ilium, thoracolumbar fascia, erector spinae aponeurosis, sacrum, coccyx, dorsal sacroiliac and sacrotuberous ligaments in all specimens. Their mean fascicle orientation ranged from 32 to 45° below horizontal and mean length from 11 to 18 cm. The mean total PCSA of GMax was 26 cm(2) (range 16-36), of which 70% crossed the SIJ. The average maximum force predicted to be generated by GMax's total attachments crossing each SIJ was 891 N (range 572-1,215), of which 70% (702 N: range 450-1,009) could act perpendicular to the plane of the SIJ. The capacity of GMax to generate an extensor moment at lower lumbar segments was estimated at 4 Nm (range 2-9.5). GMax may generate compressive forces at the SIJ through its bony and fibrous attachments. These may assist effective load transfer between lower limbs and trunk. Copyright © 2013 Wiley Periodicals, Inc.

Fibrocartilage tissue engineering: the role of the stress environment on cell morphology and matrix expression.

PubMed

Thomopoulos, Stavros; Das, Rosalina; Birman, Victor; Smith, Lester; Ku, Katherine; Elson, Elliott L; Pryse, Kenneth M; Marquez, Juan Pablo; Genin, Guy M

2011-04-01

Although much is known about the effects of uniaxial mechanical loading on fibrocartilage development, the stress fields to which fibrocartilaginous regions are subjected to during development are mutiaxial. That fibrocartilage develops at tendon-to-bone attachments and in compressive regions of tendons is well established. However, the three-dimensional (3D) nature of the stresses needed for the development of fibrocartilage is not known. Here, we developed and applied an in vitro system to determine whether fibrocartilage can develop under a state of periodic hydrostatic tension in which only a single principal component of stress is compressive. This question is vital to efforts to mechanically guide morphogenesis and matrix expression in engineered tissue replacements. Mesenchymal stromal cells in a 3D culture were exposed to compressive and tensile stresses as a result of an external tensile hydrostatic stress field. The stress field was characterized through mechanical modeling. Tensile cyclic stresses promoted spindle-shaped cells, upregulation of scleraxis and type one collagen, and cell alignment with the direction of tension. Cells experiencing a single compressive stress component exhibited rounded cell morphology and random cell orientation. No difference in mRNA expression of the genes Sox9 and aggrecan was observed when comparing tensile and compressive regions unless the medium was supplemented with the chondrogenic factor transforming growth factor beta3. In that case, Sox9 was upregulated under static loading conditions and aggrecan was upregulated under cyclic loading conditions. In conclusion, the fibrous component of fibrocartilage could be generated using only mechanical cues, but generation of the cartilaginous component of fibrocartilage required biologic factors in addition to mechanical cues. These studies support the hypothesis that the 3D stress environment influences cell activity and gene expression in fibrocartilage development.

Fibrocartilage Tissue Engineering: The Role of the Stress Environment on Cell Morphology and Matrix Expression

PubMed Central

Das, Rosalina; Birman, Victor; Smith, Lester; Ku, Katherine; Elson, Elliott L.; Pryse, Kenneth M.; Marquez, Juan Pablo; Genin, Guy M.

2011-01-01

Although much is known about the effects of uniaxial mechanical loading on fibrocartilage development, the stress fields to which fibrocartilaginous regions are subjected to during development are mutiaxial. That fibrocartilage develops at tendon-to-bone attachments and in compressive regions of tendons is well established. However, the three-dimensional (3D) nature of the stresses needed for the development of fibrocartilage is not known. Here, we developed and applied an in vitro system to determine whether fibrocartilage can develop under a state of periodic hydrostatic tension in which only a single principal component of stress is compressive. This question is vital to efforts to mechanically guide morphogenesis and matrix expression in engineered tissue replacements. Mesenchymal stromal cells in a 3D culture were exposed to compressive and tensile stresses as a result of an external tensile hydrostatic stress field. The stress field was characterized through mechanical modeling. Tensile cyclic stresses promoted spindle-shaped cells, upregulation of scleraxis and type one collagen, and cell alignment with the direction of tension. Cells experiencing a single compressive stress component exhibited rounded cell morphology and random cell orientation. No difference in mRNA expression of the genes Sox9 and aggrecan was observed when comparing tensile and compressive regions unless the medium was supplemented with the chondrogenic factor transforming growth factor beta3. In that case, Sox9 was upregulated under static loading conditions and aggrecan was upregulated under cyclic loading conditions. In conclusion, the fibrous component of fibrocartilage could be generated using only mechanical cues, but generation of the cartilaginous component of fibrocartilage required biologic factors in addition to mechanical cues. These studies support the hypothesis that the 3D stress environment influences cell activity and gene expression in fibrocartilage development. PMID:21091338

Determination of friction coefficient in unconfined compression of brain tissue.

PubMed

Rashid, Badar; Destrade, Michel; Gilchrist, Michael D

2012-10-01

Unconfined compression tests are more convenient to perform on cylindrical samples of brain tissue than tensile tests in order to estimate mechanical properties of the brain tissue because they allow homogeneous deformations. The reliability of these tests depends significantly on the amount of friction generated at the specimen/platen interface. Thus, there is a crucial need to find an approximate value of the friction coefficient in order to predict a possible overestimation of stresses during unconfined compression tests. In this study, a combined experimental-computational approach was adopted to estimate the dynamic friction coefficient μ of porcine brain matter against metal platens in compressive tests. Cylindrical samples of porcine brain tissue were tested up to 30% strain at variable strain rates, both under bonded and lubricated conditions in the same controlled environment. It was established that μ was equal to 0.09±0.03, 0.18±0.04, 0.18±0.04 and 0.20±0.02 at strain rates of 1, 30, 60 and 90/s, respectively. Additional tests were also performed to analyze brain tissue under lubricated and bonded conditions, with and without initial contact of the top platen with the brain tissue, with different specimen aspect ratios and with different lubricants (Phosphate Buffer Saline (PBS), Polytetrafluoroethylene (PTFE) and Silicone). The test conditions (lubricant used, biological tissue, loading velocity) adopted in this study were similar to the studies conducted by other research groups. This study will help to understand the amount of friction generated during unconfined compression of brain tissue for strain rates of up to 90/s. Copyright © 2012 Elsevier Ltd. All rights reserved.

Random lattice structures. Modelling, manufacture and FEA of their mechanical response

NASA Astrophysics Data System (ADS)

Maliaris, G.; Sarafis, I. T.; Lazaridis, T.; Varoutoglou, A.; Tsakataras, G.

2016-11-01

The implementation of lightweight structures in various applications, especially in Aerospace/ Automotive industries and Orthopaedics, has become a necessity due to their exceptional mechanical properties with respect to reduced weight. In this work we present a Voronoi tessellation based algorithm, which has been developed for modelling stochastic lattice structures. With the proposed algorithm, is possible to generate CAD geometry with controllable structural parameters, such as porosity, cell number and strut thickness. The digital structures were transformed into physical objects through the combination of 3D printing technics and investment casting. This process was applied to check the mechanical behaviour of generated digital models. Until now, the only way to materialize such structures into physical objects, was feasible through 3D printing methods such as Selective Laser Sintering/ Melting (SLS/ SLM). Investment casting possesses numerous advantages against SLS or SLA, with the major one being the material variety. On the other hand, several trials are required in order to calibrate the process parameters to have successful castings, which is the major drawback of investment casting. The manufactured specimens were subjected to compression tests, where their mechanical response was registered in the form of compressive load - displacement curves. Also, a finite element model was developed, using the specimens’ CAD data and compression test parameters. The FE assisted calculation of specimen plastic deformation is identical with the one of the physical object, which validates the conclusions drawn from the simulation results. As it was observed, strut contact is initiated when specimen deformation is approximately 5mm. Although FE calculated compressive force follows the same trend for the first 3mm of compression, then diverges because of the elasto-plastic FE model type definition and the occurred remeshing steps.

Fractal-Based Image Compression

DTIC Science & Technology

1989-09-01

6. A Mercedes Benz symbol generated using an IFS code ................. 21 7. (a) U-A fern and (b) A-0 fern generated with RIFS codes...22 8. Construction of the Mercedes - Benz symbol using RIFS ................ 23 9. The regenerated perfect image of the Mercedes - Benz symbol using R IF...quite often, it cannot be done with a reasonable number of transforms. As an example, the Mercedes Benz symbol generated using an IFS code is illustrated

Model-based VQ for image data archival, retrieval and distribution

NASA Technical Reports Server (NTRS)

Manohar, Mareboyana; Tilton, James C.

1995-01-01

An ideal image compression technique for image data archival, retrieval and distribution would be one with the asymmetrical computational requirements of Vector Quantization (VQ), but without the complications arising from VQ codebooks. Codebook generation and maintenance are stumbling blocks which have limited the use of VQ as a practical image compression algorithm. Model-based VQ (MVQ), a variant of VQ described here, has the computational properties of VQ but does not require explicit codebooks. The codebooks are internally generated using mean removed error and Human Visual System (HVS) models. The error model assumed is the Laplacian distribution with mean, lambda-computed from a sample of the input image. A Laplacian distribution with mean, lambda, is generated with uniform random number generator. These random numbers are grouped into vectors. These vectors are further conditioned to make them perceptually meaningful by filtering the DCT coefficients from each vector. The DCT coefficients are filtered by multiplying by a weight matrix that is found to be optimal for human perception. The inverse DCT is performed to produce the conditioned vectors for the codebook. The only image dependent parameter used in the generation of codebook is the mean, lambda, that is included in the coded file to repeat the codebook generation process for decoding.

Neural network wavelet technology: A frontier of automation

NASA Technical Reports Server (NTRS)

Szu, Harold

1994-01-01

Neural networks are an outgrowth of interdisciplinary studies concerning the brain. These studies are guiding the field of Artificial Intelligence towards the, so-called, 6th Generation Computer. Enormous amounts of resources have been poured into R/D. Wavelet Transforms (WT) have replaced Fourier Transforms (FT) in Wideband Transient (WT) cases since the discovery of WT in 1985. The list of successful applications includes the following: earthquake prediction; radar identification; speech recognition; stock market forecasting; FBI finger print image compression; and telecommunication ISDN-data compression.

Compressed air energy storage system

DOEpatents

Ahrens, Frederick W.; Kartsounes, George T.

1981-01-01

An internal combustion reciprocating engine is operable as a compressor during slack demand periods utilizing excess power from a power grid to charge air into an air storage reservoir and as an expander during peak demand periods to feed power into the power grid utilizing air obtained from the air storage reservoir together with combustible fuel. Preferably the internal combustion reciprocating engine is operated at high pressure and a low pressure turbine and compressor are also employed for air compression and power generation.

Air-guided photonic-crystal-fiber pulse-compression delivery of multimegawatt femtosecond laser output for nonlinear-optical imaging and neurosurgery

NASA Astrophysics Data System (ADS)

Lanin, Aleksandr A.; Fedotov, Il'ya V.; Sidorov-Biryukov, Dmitrii A.; Doronina-Amitonova, Lyubov V.; Ivashkina, Olga I.; Zots, Marina A.; Sun, Chi-Kuang; Ömer Ilday, F.; Fedotov, Andrei B.; Anokhin, Konstantin V.; Zheltikov, Aleksei M.

2012-03-01

Large-core hollow photonic-crystal fibers (PCFs) are shown to enable a fiber-format air-guided delivery of ultrashort infrared laser pulses for neurosurgery and nonlinear-optical imaging. With an appropriate dispersion precompensation, an anomalously dispersive 15-μm-core hollow PCF compresses 510-fs, 1070-nm light pulses to a pulse width of about 110 fs, providing a peak power in excess of 5 MW. The compressed PCF output is employed to induce a local photodisruption of corpus callosum tissues in mouse brain and is used to generate the third harmonic in brain tissues, which is captured by the PCF and delivered to a detector through the PCF cladding.

Development of a hybrid chemical/mechanical heat pump

NASA Technical Reports Server (NTRS)

Grzyll, Lawrence R.; Silvestri, John J.; Scaringe, Robert P.

1991-01-01

The authors present the current development status of a hybrid chemical/mechanical heat pump for low-lift applications. The heat pump provides electronics cooling by evaporating a pure refrigerant from an absorbent/refrigerant mixture in a generator/cold plate. The current development focused on evaluation of absorbent/refrigerant pairs, corrosion testing, pump and compressor design, and electronic cold plate design. Two cycle configurations were considered. The first configuration utilized a standard mechanical compressor and pump. The second cycle configuration investigated pumps and compressors with non-moving parts. An innovative generator/cold plate design is also presented. The development to date shows that this cycle has about the same performance as standard vapor compression heat pumps with standard refrigerants but may have some performance and reliability advantages over vapor compression heat pumps.

Generation of 70-fs pulses at 286 μm from a mid-infrared fiber laser

NASA Astrophysics Data System (ADS)

Woodward, R. I.; Hudson, D. D.; Fuerbach, A.; Jackson, S. D.

2017-12-01

We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-infrared fiber laser through nonlinear compression of pulses from a holmium-doped fiber oscillator using a short length of chalcogenide fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 {\\mu}m are spectrally broadened through self-phase modulation in step-index As2S3 fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-infrared fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.

Occam’s Quantum Strop: Synchronizing and Compressing Classical Cryptic Processes via a Quantum Channel

NASA Astrophysics Data System (ADS)

Mahoney, John R.; Aghamohammadi, Cina; Crutchfield, James P.

2016-02-01

A stochastic process’ statistical complexity stands out as a fundamental property: the minimum information required to synchronize one process generator to another. How much information is required, though, when synchronizing over a quantum channel? Recent work demonstrated that representing causal similarity as quantum state-indistinguishability provides a quantum advantage. We generalize this to synchronization and offer a sequence of constructions that exploit extended causal structures, finding substantial increase of the quantum advantage. We demonstrate that maximum compression is determined by the process’ cryptic order-a classical, topological property closely allied to Markov order, itself a measure of historical dependence. We introduce an efficient algorithm that computes the quantum advantage and close noting that the advantage comes at a cost-one trades off prediction for generation complexity.

Precise measurement of a magnetic field generated by the electromagnetic flux compression technique.

PubMed

Nakamura, D; Sawabe, H; Matsuda, Y H; Takeyama, S

2013-04-01

The precision of the values of a magnetic field generated by electromagnetic flux compression was investigated in ultra-high magnetic fields of up to 700 T. In an attempt to calibrate the magnetic field measured by pickup coils, precise Faraday rotation (FR) measurements were conducted on optical (quartz and crown) glasses. A discernible "turn-around" phenomenon was observed in the FR signal as well as the pickup coils before the end of a liner implosion. We found that the magnetic field measured by pickup coils should be corrected by taking into account the high-frequency response of the signal transmission line. Near the peak magnetic field, however, the pickup coils failed to provide reliable values, leaving the FR measurement as the only method to precisely measure extremely high magnetic fields.

Occam's Quantum Strop: Synchronizing and Compressing Classical Cryptic Processes via a Quantum Channel.

PubMed

Mahoney, John R; Aghamohammadi, Cina; Crutchfield, James P

2016-02-15

A stochastic process' statistical complexity stands out as a fundamental property: the minimum information required to synchronize one process generator to another. How much information is required, though, when synchronizing over a quantum channel? Recent work demonstrated that representing causal similarity as quantum state-indistinguishability provides a quantum advantage. We generalize this to synchronization and offer a sequence of constructions that exploit extended causal structures, finding substantial increase of the quantum advantage. We demonstrate that maximum compression is determined by the process' cryptic order--a classical, topological property closely allied to Markov order, itself a measure of historical dependence. We introduce an efficient algorithm that computes the quantum advantage and close noting that the advantage comes at a cost-one trades off prediction for generation complexity.

30W, 10μJ, 10-ps SPM-induced spectrally compressed pulse generation in a low non-linearity ytterbium-doped rod-type fibre amplifier

NASA Astrophysics Data System (ADS)

Zaouter, Y.; Cormier, E.; Rigail, P.; Hönninger, C.; Mottay, E.

2007-02-01

The concept of spectral compression induced by self phase modulation is used to generate transform-limited 10ps pulses in a rare-earth-doped low nonlinearity fibre amplifier. The seed source of the amplifier stage is a high power, Yb 3+:KGW bulk oscillator which delivers 500 fs transform-limited pulses at 10MHz repetition rate. After a reduction of the repetition rate down to 3MHz, the femtosecond pulses are negatively chirped by transmission gratings in a compressor arrangement. The resulting 10ps pulses are further seeded into the power amplifier and up to 32W output power is obtained while the spectral bandwidth is reduced to less than 0.5 nm by means of self phase modulation.

Evaluating lossy data compression on climate simulation data within a large ensemble

DOE PAGES

Baker, Allison H.; Hammerling, Dorit M.; Mickelson, Sheri A.; ...

2016-12-07

High-resolution Earth system model simulations generate enormous data volumes, and retaining the data from these simulations often strains institutional storage resources. Further, these exceedingly large storage requirements negatively impact science objectives, for example, by forcing reductions in data output frequency, simulation length, or ensemble size. To lessen data volumes from the Community Earth System Model (CESM), we advocate the use of lossy data compression techniques. While lossy data compression does not exactly preserve the original data (as lossless compression does), lossy techniques have an advantage in terms of smaller storage requirements. To preserve the integrity of the scientific simulation data,more » the effects of lossy data compression on the original data should, at a minimum, not be statistically distinguishable from the natural variability of the climate system, and previous preliminary work with data from CESM has shown this goal to be attainable. However, to ultimately convince climate scientists that it is acceptable to use lossy data compression, we provide climate scientists with access to publicly available climate data that have undergone lossy data compression. In particular, we report on the results of a lossy data compression experiment with output from the CESM Large Ensemble (CESM-LE) Community Project, in which we challenge climate scientists to examine features of the data relevant to their interests, and attempt to identify which of the ensemble members have been compressed and reconstructed. We find that while detecting distinguishing features is certainly possible, the compression effects noticeable in these features are often unimportant or disappear in post-processing analyses. In addition, we perform several analyses that directly compare the original data to the reconstructed data to investigate the preservation, or lack thereof, of specific features critical to climate science. Overall, we conclude that applying lossy data compression to climate simulation data is both advantageous in terms of data reduction and generally acceptable in terms of effects on scientific results.« less

Thermofluidic compression effects to achieve combustion in a low-compression scramjet engine

NASA Astrophysics Data System (ADS)

Moura, A. F.; Wheatley, V.; Jahn, I.

2018-07-01

The compression provided by a scramjet inlet is an important parameter in its design. It must be low enough to limit thermal and structural loads and stagnation pressure losses, but high enough to provide the conditions favourable for combustion. Inlets are typically designed to achieve sufficient compression without accounting for the fluidic, and subsequently thermal, compression provided by the fuel injection, which can enable robust combustion in a low-compression engine. This is investigated using Reynolds-averaged Navier-Stokes numerical simulations of a simplified scramjet engine designed to have insufficient compression to auto-ignite fuel in the absence of thermofluidic compression. The engine was designed with a wide rectangular combustor and a single centrally located injector, in order to reduce three-dimensional effects of the walls on the fuel plume. By varying the injected mass flow rate of hydrogen fuel (equivalence ratios of 0.22, 0.17, and 0.13), it is demonstrated that higher equivalence ratios lead to earlier ignition and more rapid combustion, even though mean conditions in the combustor change by no more than 5% for pressure and 3% for temperature with higher equivalence ratio. By supplementing the lower equivalence ratio with helium to achieve a higher mass flow rate, it is confirmed that these benefits are primarily due to the local compression provided by the extra injected mass. Investigation of the conditions around the fuel plume indicated two connected mechanisms. The higher mass flow rate for higher equivalence ratios generated a stronger injector bow shock that compresses the free-stream gas, increasing OH radical production and promoting ignition. This was observed both in the higher equivalence ratio case and in the case with helium. This earlier ignition led to increased temperature and pressure downstream and, consequently, stronger combustion. The heat release from combustion provided thermal compression in the combustor, further increasing combustion efficiency.

Evaluating lossy data compression on climate simulation data within a large ensemble

NASA Astrophysics Data System (ADS)

Baker, Allison H.; Hammerling, Dorit M.; Mickelson, Sheri A.; Xu, Haiying; Stolpe, Martin B.; Naveau, Phillipe; Sanderson, Ben; Ebert-Uphoff, Imme; Samarasinghe, Savini; De Simone, Francesco; Carbone, Francesco; Gencarelli, Christian N.; Dennis, John M.; Kay, Jennifer E.; Lindstrom, Peter

2016-12-01

High-resolution Earth system model simulations generate enormous data volumes, and retaining the data from these simulations often strains institutional storage resources. Further, these exceedingly large storage requirements negatively impact science objectives, for example, by forcing reductions in data output frequency, simulation length, or ensemble size. To lessen data volumes from the Community Earth System Model (CESM), we advocate the use of lossy data compression techniques. While lossy data compression does not exactly preserve the original data (as lossless compression does), lossy techniques have an advantage in terms of smaller storage requirements. To preserve the integrity of the scientific simulation data, the effects of lossy data compression on the original data should, at a minimum, not be statistically distinguishable from the natural variability of the climate system, and previous preliminary work with data from CESM has shown this goal to be attainable. However, to ultimately convince climate scientists that it is acceptable to use lossy data compression, we provide climate scientists with access to publicly available climate data that have undergone lossy data compression. In particular, we report on the results of a lossy data compression experiment with output from the CESM Large Ensemble (CESM-LE) Community Project, in which we challenge climate scientists to examine features of the data relevant to their interests, and attempt to identify which of the ensemble members have been compressed and reconstructed. We find that while detecting distinguishing features is certainly possible, the compression effects noticeable in these features are often unimportant or disappear in post-processing analyses. In addition, we perform several analyses that directly compare the original data to the reconstructed data to investigate the preservation, or lack thereof, of specific features critical to climate science. Overall, we conclude that applying lossy data compression to climate simulation data is both advantageous in terms of data reduction and generally acceptable in terms of effects on scientific results.

Fast lossless compression via cascading Bloom filters

PubMed Central

2014-01-01

Background Data from large Next Generation Sequencing (NGS) experiments present challenges both in terms of costs associated with storage and in time required for file transfer. It is sometimes possible to store only a summary relevant to particular applications, but generally it is desirable to keep all information needed to revisit experimental results in the future. Thus, the need for efficient lossless compression methods for NGS reads arises. It has been shown that NGS-specific compression schemes can improve results over generic compression methods, such as the Lempel-Ziv algorithm, Burrows-Wheeler transform, or Arithmetic Coding. When a reference genome is available, effective compression can be achieved by first aligning the reads to the reference genome, and then encoding each read using the alignment position combined with the differences in the read relative to the reference. These reference-based methods have been shown to compress better than reference-free schemes, but the alignment step they require demands several hours of CPU time on a typical dataset, whereas reference-free methods can usually compress in minutes. Results We present a new approach that achieves highly efficient compression by using a reference genome, but completely circumvents the need for alignment, affording a great reduction in the time needed to compress. In contrast to reference-based methods that first align reads to the genome, we hash all reads into Bloom filters to encode, and decode by querying the same Bloom filters using read-length subsequences of the reference genome. Further compression is achieved by using a cascade of such filters. Conclusions Our method, called BARCODE, runs an order of magnitude faster than reference-based methods, while compressing an order of magnitude better than reference-free methods, over a broad range of sequencing coverage. In high coverage (50-100 fold), compared to the best tested compressors, BARCODE saves 80-90% of the running time while only increasing space slightly. PMID:25252952

Evaluating lossy data compression on climate simulation data within a large ensemble

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

Baker, Allison H.; Hammerling, Dorit M.; Mickelson, Sheri A.

High-resolution Earth system model simulations generate enormous data volumes, and retaining the data from these simulations often strains institutional storage resources. Further, these exceedingly large storage requirements negatively impact science objectives, for example, by forcing reductions in data output frequency, simulation length, or ensemble size. To lessen data volumes from the Community Earth System Model (CESM), we advocate the use of lossy data compression techniques. While lossy data compression does not exactly preserve the original data (as lossless compression does), lossy techniques have an advantage in terms of smaller storage requirements. To preserve the integrity of the scientific simulation data,more » the effects of lossy data compression on the original data should, at a minimum, not be statistically distinguishable from the natural variability of the climate system, and previous preliminary work with data from CESM has shown this goal to be attainable. However, to ultimately convince climate scientists that it is acceptable to use lossy data compression, we provide climate scientists with access to publicly available climate data that have undergone lossy data compression. In particular, we report on the results of a lossy data compression experiment with output from the CESM Large Ensemble (CESM-LE) Community Project, in which we challenge climate scientists to examine features of the data relevant to their interests, and attempt to identify which of the ensemble members have been compressed and reconstructed. We find that while detecting distinguishing features is certainly possible, the compression effects noticeable in these features are often unimportant or disappear in post-processing analyses. In addition, we perform several analyses that directly compare the original data to the reconstructed data to investigate the preservation, or lack thereof, of specific features critical to climate science. Overall, we conclude that applying lossy data compression to climate simulation data is both advantageous in terms of data reduction and generally acceptable in terms of effects on scientific results.« less

Fast lossless compression via cascading Bloom filters.

PubMed

Rozov, Roye; Shamir, Ron; Halperin, Eran

2014-01-01

Data from large Next Generation Sequencing (NGS) experiments present challenges both in terms of costs associated with storage and in time required for file transfer. It is sometimes possible to store only a summary relevant to particular applications, but generally it is desirable to keep all information needed to revisit experimental results in the future. Thus, the need for efficient lossless compression methods for NGS reads arises. It has been shown that NGS-specific compression schemes can improve results over generic compression methods, such as the Lempel-Ziv algorithm, Burrows-Wheeler transform, or Arithmetic Coding. When a reference genome is available, effective compression can be achieved by first aligning the reads to the reference genome, and then encoding each read using the alignment position combined with the differences in the read relative to the reference. These reference-based methods have been shown to compress better than reference-free schemes, but the alignment step they require demands several hours of CPU time on a typical dataset, whereas reference-free methods can usually compress in minutes. We present a new approach that achieves highly efficient compression by using a reference genome, but completely circumvents the need for alignment, affording a great reduction in the time needed to compress. In contrast to reference-based methods that first align reads to the genome, we hash all reads into Bloom filters to encode, and decode by querying the same Bloom filters using read-length subsequences of the reference genome. Further compression is achieved by using a cascade of such filters. Our method, called BARCODE, runs an order of magnitude faster than reference-based methods, while compressing an order of magnitude better than reference-free methods, over a broad range of sequencing coverage. In high coverage (50-100 fold), compared to the best tested compressors, BARCODE saves 80-90% of the running time while only increasing space slightly.

High-speed and high-ratio referential genome compression.

PubMed

Liu, Yuansheng; Peng, Hui; Wong, Limsoon; Li, Jinyan

2017-11-01

The rapidly increasing number of genomes generated by high-throughput sequencing platforms and assembly algorithms is accompanied by problems in data storage, compression and communication. Traditional compression algorithms are unable to meet the demand of high compression ratio due to the intrinsic challenging features of DNA sequences such as small alphabet size, frequent repeats and palindromes. Reference-based lossless compression, by which only the differences between two similar genomes are stored, is a promising approach with high compression ratio. We present a high-performance referential genome compression algorithm named HiRGC. It is based on a 2-bit encoding scheme and an advanced greedy-matching search on a hash table. We compare the performance of HiRGC with four state-of-the-art compression methods on a benchmark dataset of eight human genomes. HiRGC takes <30 min to compress about 21 gigabytes of each set of the seven target genomes into 96-260 megabytes, achieving compression ratios of 217 to 82 times. This performance is at least 1.9 times better than the best competing algorithm on its best case. Our compression speed is also at least 2.9 times faster. HiRGC is stable and robust to deal with different reference genomes. In contrast, the competing methods' performance varies widely on different reference genomes. More experiments on 100 human genomes from the 1000 Genome Project and on genomes of several other species again demonstrate that HiRGC's performance is consistently excellent. The C ++ and Java source codes of our algorithm are freely available for academic and non-commercial use. They can be downloaded from https://github.com/yuansliu/HiRGC. jinyan.li@uts.edu.au. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Thermofluidic compression effects to achieve combustion in a low-compression scramjet engine

NASA Astrophysics Data System (ADS)

Moura, A. F.; Wheatley, V.; Jahn, I.

2017-12-01

The compression provided by a scramjet inlet is an important parameter in its design. It must be low enough to limit thermal and structural loads and stagnation pressure losses, but high enough to provide the conditions favourable for combustion. Inlets are typically designed to achieve sufficient compression without accounting for the fluidic, and subsequently thermal, compression provided by the fuel injection, which can enable robust combustion in a low-compression engine. This is investigated using Reynolds-averaged Navier-Stokes numerical simulations of a simplified scramjet engine designed to have insufficient compression to auto-ignite fuel in the absence of thermofluidic compression. The engine was designed with a wide rectangular combustor and a single centrally located injector, in order to reduce three-dimensional effects of the walls on the fuel plume. By varying the injected mass flow rate of hydrogen fuel (equivalence ratios of 0.22, 0.17, and 0.13), it is demonstrated that higher equivalence ratios lead to earlier ignition and more rapid combustion, even though mean conditions in the combustor change by no more than 5% for pressure and 3% for temperature with higher equivalence ratio. By supplementing the lower equivalence ratio with helium to achieve a higher mass flow rate, it is confirmed that these benefits are primarily due to the local compression provided by the extra injected mass. Investigation of the conditions around the fuel plume indicated two connected mechanisms. The higher mass flow rate for higher equivalence ratios generated a stronger injector bow shock that compresses the free-stream gas, increasing OH radical production and promoting ignition. This was observed both in the higher equivalence ratio case and in the case with helium. This earlier ignition led to increased temperature and pressure downstream and, consequently, stronger combustion. The heat release from combustion provided thermal compression in the combustor, further increasing combustion efficiency.

An efficient compression scheme for bitmap indices

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

Wu, Kesheng; Otoo, Ekow J.; Shoshani, Arie

2004-04-13

When using an out-of-core indexing method to answer a query, it is generally assumed that the I/O cost dominates the overall query response time. Because of this, most research on indexing methods concentrate on reducing the sizes of indices. For bitmap indices, compression has been used for this purpose. However, in most cases, operations on these compressed bitmaps, mostly bitwise logical operations such as AND, OR, and NOT, spend more time in CPU than in I/O. To speedup these operations, a number of specialized bitmap compression schemes have been developed; the best known of which is the byte-aligned bitmap codemore » (BBC). They are usually faster in performing logical operations than the general purpose compression schemes, but, the time spent in CPU still dominates the total query response time. To reduce the query response time, we designed a CPU-friendly scheme named the word-aligned hybrid (WAH) code. In this paper, we prove that the sizes of WAH compressed bitmap indices are about two words per row for large range of attributes. This size is smaller than typical sizes of commonly used indices, such as a B-tree. Therefore, WAH compressed indices are not only appropriate for low cardinality attributes but also for high cardinality attributes.In the worst case, the time to operate on compressed bitmaps is proportional to the total size of the bitmaps involved. The total size of the bitmaps required to answer a query on one attribute is proportional to the number of hits. These indicate that WAH compressed bitmap indices are optimal. To verify their effectiveness, we generated bitmap indices for four different datasets and measured the response time of many range queries. Tests confirm that sizes of compressed bitmap indices are indeed smaller than B-tree indices, and query processing with WAH compressed indices is much faster than with BBC compressed indices, projection indices and B-tree indices. In addition, we also verified that the average query response time is proportional to the index size. This indicates that the compressed bitmap indices are efficient for very large datasets.« less

Modular approach to achieving the next-generation X-ray light source

NASA Astrophysics Data System (ADS)

Biedron, S. G.; Milton, S. V.; Freund, H. P.

2001-12-01

A modular approach to the next-generation light source is described. The "modules" include photocathode, radio-frequency, electron guns and their associated drive-laser systems, linear accelerators, bunch-compression systems, seed laser systems, planar undulators, two-undulator harmonic generation schemes, high-gain harmonic generation systems, nonlinear higher harmonics, and wavelength shifting. These modules will be helpful in distributing the next-generation light source to many more laboratories than the current single-pass, high-gain free-electron laser designs permit, due to both monetary and/or physical space constraints.

NRGC: a novel referential genome compression algorithm.

PubMed

Saha, Subrata; Rajasekaran, Sanguthevar

2016-11-15

Next-generation sequencing techniques produce millions to billions of short reads. The procedure is not only very cost effective but also can be done in laboratory environment. The state-of-the-art sequence assemblers then construct the whole genomic sequence from these reads. Current cutting edge computing technology makes it possible to build genomic sequences from the billions of reads within a minimal cost and time. As a consequence, we see an explosion of biological sequences in recent times. In turn, the cost of storing the sequences in physical memory or transmitting them over the internet is becoming a major bottleneck for research and future medical applications. Data compression techniques are one of the most important remedies in this context. We are in need of suitable data compression algorithms that can exploit the inherent structure of biological sequences. Although standard data compression algorithms are prevalent, they are not suitable to compress biological sequencing data effectively. In this article, we propose a novel referential genome compression algorithm (NRGC) to effectively and efficiently compress the genomic sequences. We have done rigorous experiments to evaluate NRGC by taking a set of real human genomes. The simulation results show that our algorithm is indeed an effective genome compression algorithm that performs better than the best-known algorithms in most of the cases. Compression and decompression times are also very impressive. The implementations are freely available for non-commercial purposes. They can be downloaded from: http://www.engr.uconn.edu/~rajasek/NRGC.zip CONTACT: rajasek@engr.uconn.edu. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Development and validation of an improved mechanical thorax for simulating cardiopulmonary resuscitation with adjustable chest stiffness and simulated blood flow.

PubMed

Eichhorn, Stefan; Spindler, Johannes; Polski, Marcin; Mendoza, Alejandro; Schreiber, Ulrich; Heller, Michael; Deutsch, Marcus Andre; Braun, Christian; Lange, Rüdiger; Krane, Markus

2017-05-01

Investigations of compressive frequency, duty cycle, or waveform during CPR are typically rooted in animal research or computer simulations. Our goal was to generate a mechanical model incorporating alternate stiffness settings and an integrated blood flow system, enabling defined, reproducible comparisons of CPR efficacy. Based on thoracic stiffness data measured in human cadavers, such a model was constructed using valve-controlled pneumatic pistons and an artificial heart. This model offers two realistic levels of chest elasticity, with a blood flow apparatus that reflects compressive depth and waveform changes. We conducted CPR at opposing levels of physiologic stiffness, using a LUCAS device, a motor-driven plunger, and a group of volunteers. In high-stiffness mode, blood flow generated by volunteers was significantly less after just 2min of CPR, whereas flow generated by LUCAS device was superior by comparison. Optimal blood flow was obtained via motor-driven plunger, with trapezoidal waveform. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Productivity of "collisions generate heat" for reconciling an energy model with mechanistic reasoning: A case study

NASA Astrophysics Data System (ADS)

Scherr, Rachel E.; Robertson, Amy D.

2015-06-01

We observe teachers in professional development courses about energy constructing mechanistic accounts of energy transformations. We analyze a case in which teachers investigating adiabatic compression develop a model of the transformation of kinetic energy to thermal energy. Among their ideas is the idea that thermal energy is generated as a byproduct of individual particle collisions, which is represented in science education research literature as an obstacle to learning. We demonstrate that in this instructional context, the idea that individual particle collisions generate thermal energy is not an obstacle to learning, but instead is productive: it initiates intellectual progress. Specifically, this idea initiates the reconciliation of the teachers' energy model with mechanistic reasoning about adiabatic compression, and leads to a canonically correct model of the transformation of kinetic energy into thermal energy. We claim that the idea's productivity is influenced by features of our particular instructional context, including the instructional goals of the course, the culture of collaborative sense making, and the use of certain representations of energy.

Scavenging energy from human walking through a shoe-mounted piezoelectric harvester

NASA Astrophysics Data System (ADS)

Fan, Kangqi; Liu, Zhaohui; Liu, Haiyan; Wang, Liansong; Zhu, Yingmin; Yu, Bo

2017-04-01

This study presents a shoe-mounted nonlinear piezoelectric energy harvester (PEH) with intent to capture energy from human walking. The PEH consists of a piezoelectric cantilever beam magnetically coupled to a ferromagnetic ball and a crossbeam. A sleeve is included to guide the travel of the ball. Experimental measurements and theoretical simulations demonstrate that the proposed design can collect energy from diverse excitation sources with different directions produced by the foot, including vibrations, swing motions, and the compressive force. The ball and the crossbeam sense the swing motion and the compressive force, respectively, and then actuate the piezoelectric beam to function. The piezoelectric beam senses the vibration along the tibial axis and generates electricity. The proposed PEH achieves the superposition of these excitations and generates multiple peaks in voltage output within one gait cycle. The output power generated by the fabricated prototype ranges from 0.03 mW to 0.35 mW when the walking velocity varies from 2 km/h to 8 km/h.

Development of compact explosively driven ferromagnetic seed source for helical magnetic flux compression generator

NASA Astrophysics Data System (ADS)

Liu, Peng; Zhang, He; Ma, Shaojie; Shi, Yunlei

2018-05-01

A compact explosively driven ferromagnetic generator (FMG) is developed for seed power source of helical magnetic flux compression generator (HMFCG). The mechanism of FMG is studied by establishing a magnetoelectric conversion model. Analytical calculations and numerical simulations are conducted on the magnetostatic field of open-circuit magnet in FMG. The calculation method for the magnet's cross-sectional magnetic flux is obtained. The pulse sources made of different materials and equipped with different initiation modes are experimentally explored. Besides, the dynamic coupling experiments of FMG and HMFCG are carried out. The results show that, N35 single-ended and double-ended initiating FMGs have an energy conversion efficiency ηt not less than 14.6% and 24.4%, respectively; FMG has an output pulse current not less than 4kA and an energy of about 3J on 320nH inductive load; HMFCG experiences energy gains of about 2-3 times. FMG and HMFCG can be coupled to form a full-blast electrical driving pulse source.

Piezo-generator integrating a vertical array of GaN nanowires.

PubMed

Jamond, N; Chrétien, P; Houzé, F; Lu, L; Largeau, L; Maugain, O; Travers, L; Harmand, J C; Glas, F; Lefeuvre, E; Tchernycheva, M; Gogneau, N

2016-08-12

We demonstrate the first piezo-generator integrating a vertical array of GaN nanowires (NWs). We perform a systematic multi-scale analysis, going from single wire properties to macroscopic device fabrication and characterization, which allows us to establish for GaN NWs the relationship between the material properties and the piezo-generation, and to propose an efficient piezo-generator design. The piezo-conversion of individual MBE-grown p-doped GaN NWs in a dense array is assessed by atomic force microscopy (AFM) equipped with a Resiscope module yielding an average output voltage of 228 ± 120 mV and a maximum value of 350 mV generated per NW. In the case of p-doped GaN NWs, the piezo-generation is achieved when a positive piezo-potential is created inside the nanostructures, i.e. when the NWs are submitted to compressive deformation. The understanding of the piezo-generation mechanism in our GaN NWs, gained from AFM analyses, is applied to design a piezo-generator operated under compressive strain. The device consists of NW arrays of several square millimeters in size embedded into spin-on glass with a Schottky contact for rectification and collection of piezo-generated carriers. The generator delivers a maximum power density of ∼12.7 mW cm(-3). This value sets the new state of the art for piezo-generators based on GaN NWs and more generally on nitride NWs, and offers promising prospects for the use of GaN NWs as high-efficiency ultra-compact energy harvesters.

Compressive sensing for efficient health monitoring and effective damage detection of structures

NASA Astrophysics Data System (ADS)

Jayawardhana, Madhuka; Zhu, Xinqun; Liyanapathirana, Ranjith; Gunawardana, Upul

2017-02-01

Real world Structural Health Monitoring (SHM) systems consist of sensors in the scale of hundreds, each sensor generating extremely large amounts of data, often arousing the issue of the cost associated with data transfer and storage. Sensor energy is a major component included in this cost factor, especially in Wireless Sensor Networks (WSN). Data compression is one of the techniques that is being explored to mitigate the effects of these issues. In contrast to traditional data compression techniques, Compressive Sensing (CS) - a very recent development - introduces the means of accurately reproducing a signal by acquiring much less number of samples than that defined by Nyquist's theorem. CS achieves this task by exploiting the sparsity of the signal. By the reduced amount of data samples, CS may help reduce the energy consumption and storage costs associated with SHM systems. This paper investigates CS based data acquisition in SHM, in particular, the implications of CS on damage detection and localization. CS is implemented in a simulation environment to compress structural response data from a Reinforced Concrete (RC) structure. Promising results were obtained from the compressed data reconstruction process as well as the subsequent damage identification process using the reconstructed data. A reconstruction accuracy of 99% could be achieved at a Compression Ratio (CR) of 2.48 using the experimental data. Further analysis using the reconstructed signals provided accurate damage detection and localization results using two damage detection algorithms, showing that CS has not compromised the crucial information on structural damages during the compression process.

Nonlinear pulse compression in pulse-inversion fundamental imaging.

PubMed

Cheng, Yun-Chien; Shen, Che-Chou; Li, Pai-Chi

2007-04-01

Coded excitation can be applied in ultrasound contrast agent imaging to enhance the signal-to-noise ratio with minimal destruction of the microbubbles. Although the axial resolution is usually compromised by the requirement for a long coded transmit waveforms, this can be restored by using a compression filter to compress the received echo. However, nonlinear responses from microbubbles may cause difficulties in pulse compression and result in severe range side-lobe artifacts, particularly in pulse-inversion-based (PI) fundamental imaging. The efficacy of pulse compression in nonlinear contrast imaging was evaluated by investigating several factors relevant to PI fundamental generation using both in-vitro experiments and simulations. The results indicate that the acoustic pressure and the bubble size can alter the nonlinear characteristics of microbubbles and change the performance of the compression filter. When nonlinear responses from contrast agents are enhanced by using a higher acoustic pressure or when more microbubbles are near the resonance size of the transmit frequency, higher range side lobes are produced in both linear imaging and PI fundamental imaging. On the other hand, contrast detection in PI fundamental imaging significantly depends on the magnitude of the nonlinear responses of the bubbles and thus the resultant contrast-to-tissue ratio (CTR) still increases with acoustic pressure and the nonlinear resonance of microbubbles. It should be noted, however, that the CTR in PI fundamental imaging after compression is consistently lower than that before compression due to obvious side-lobe artifacts. Therefore, the use of coded excitation is not beneficial in PI fundamental contrast detection.

Optimization for Single-Spike X-Ray FELs at LCLS with a Low Charge Beam

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

Wang, L.; Ding, Y.; Huang, Z.

2011-12-14

The Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron radiation sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup at 20 pC charge. In the soft x-ray regime, with combination of slotted-foil or undulator taper, a single spike x-ray pulse is achievablemore » with peak FEL power of a few 10s GW. Linac Coherent Light Source (LCLS), the world's first hard x-ray Free electron laser (FEL), has started operation since 2009. With nominal operation charge of 250 pC, the generated x-ray pulse length is from 70 fs to a few hundred fs. This marks the beginning of a new era of ultrashort x-ray sciences. In addition, a low charge (20pC) operation mode has also been established. Since the collective effects are reduced at the low charge mode, we can increase the compression factor and still achieve a few kA peak current. The expected electron beam and x-ray pulses are less than 10 fs. There are growing interests in even shorter x-ray pulses, such as fs to sub-fs regime. One of the simple solutions is going to even lower charge. As discussed, single-spike x-ray pulses can be generated using 1 pC charge. However, this charge level is out of the present LCLS diagnostic range. 20 pC is a reasonable operation charge at LCLS, based on the present diagnostic system. At 20 pC in the soft x-ray wavelength regime, we have experimentally demonstrated that FEL can work at undercompression or over-compression mode, such as 1 degree off the full-compression; at full-compression, however, there is almost no lasing. In hard x-ray wavelength regime, we observed that there are reasonable photons generated even at full-compression mode, although the photon number is less than that from under-compression or over-compression mode. Since we cannot measure the x-ray pulse length at this time scale, the machine is typically optimized for generating maximum photons, not minimum pulse length. In this paper, we study the methods of producing femtosecond (or single-spike) x-ray pulses at LCLS with 20 pC charge, based on start-to-end simulations. Figure 1 shows a layout of LCLS. The compression in the second bunch compressor (BC2) determines the final e-beam bunch length. However, the laser heater, dog-leg after the main linac (DL2) and collective effects also affect the final bunch length. To adjust BC2 compression, we can either change the L2 phase or BC2 R{sub 56}. In this paper we only tune L2 phase while keep BC2 R{sub 56} fixed. For the start-to-end simulations, we used IMPACT-T and ELEGANT tracking from the photocathode to the entrance of the undulator, after that the FEL radiation was simulated with GENESIS. IMPACT-T tracks about 10{sup 6} particles in the injector part until 135 MeV, including 3D space charge force. The output particles from IMPACT-T are smoothed and increased to 12 x 10{sup 6} to reduce high-frequency numerical noise for subsequent ELEGANT simulations, which include linear and nonlinear transport effects, a 1D transient model of CSR, and longitudinal space charge effects, as well as geometric and resistive wake fields in the accelerator. In GENESIS part, the longitudinal wake field from undulator chamber and longitudinal space field are also included.« less

Productivity of "Collisions Generate Heat" for Reconciling an Energy Model with Mechanistic Reasoning: A Case Study

ERIC Educational Resources Information Center

Scherr, Rachel E.; Robertson, Amy D.

2015-01-01

We observe teachers in professional development courses about energy constructing mechanistic accounts of energy transformations. We analyze a case in which teachers investigating adiabatic compression develop a model of the transformation of kinetic energy to thermal energy. Among their ideas is the idea that thermal energy is generated as a…

Rotary Stirling-Cycle Engine And Generator

NASA Technical Reports Server (NTRS)

Chandler, Joseph A.

1990-01-01

Proposed electric-power generator comprises three motor generators coordinated by microprocessor and driven by rotary Stirling-cycle heat engine. Combination offers thermodynamic efficiency of Stirling cycle, relatively low vibration, and automatic adjustment of operating parameters to suit changing load on generator. Rotary Stirling cycle engine converts heat to power via compression and expansion of working gas between three pairs of rotary pistons on three concentric shafts in phased motion. Three motor/generators each connected to one of concentric shafts, can alternately move and be moved by pistons. Microprocessor coordinates their operation, including switching between motor and generator modes at appropriate times during each cycle.

Possible mechanism of horizontal overpressure generation of the Khibiny, Lovozero, and Kovdor ore clusters on the Kola Peninsula

NASA Astrophysics Data System (ADS)

Rebetsky, Yu. L.; Sim, L. A.; Kozyrev, A. A.

2017-07-01

The paper discusses questions related to the generation of increasing crustal horizontal compressive stresses compared to the idea of the standard gravitational state at the elastic stage or even from the prevalence of horizontal compression over vertical stress equal to the lithostatic pressure. We consider a variant of superfluous horizontal compression related to internal lithospheric processes occurrin in the crust of orogens, shields, and plates. The vertical ascending movements caused by these motions at the sole of the crust or the lithosphere pertain to these and the concomitant exogenic processes giving rise to denudation and, in particular, to erosion of the surfaces of forming rises. The residual stresses of the gravitational stressed state at the upper crust of the Kola Peninsula have been estimated for the first time. These calculations are based on the volume of sediments that have been deposited in Arctic seas beginning from the Mesozoic. The data speak to the possible level of residual horizontal compressive stresses up to 90 MPa in near-surface crustal units. This estimate is consistent with the results of in situ measurements that have been carried out at the Mining Institute of the Kola Science Center, Russian Academy of Sciences (RAS), for over 40 years. It is possible to forecast the horizontal stress gradient based on depth using our concept on the genesis of horizontal overpressure, and this forecasting is important for studying the formation of endogenic deposits.

Nonlinear pulse compression stage delivering 43-W few-cycle pulses with GW peak-power at 2-μm wavelength

NASA Astrophysics Data System (ADS)

Gebhardt, Martin; Gaida, Christian; Heuermann, T.; Stutzki, F.; Jauregui, C.; Antonio-Lopez, J.; Schüuzgen, A.; Amezcua-Correa, R.; Tünnermann, A.; Limpert, J.

2018-02-01

In this contribution we demonstrate the nonlinear pulse compression of an ultrafast thulium-doped fiber laser down to 14 fs FWHM duration (sub-3 optical cycles) at a record average power of 43 W and 34.5 μJ pulse energy. To the best of our knowledge, we present the highest average power few-cycle laser source at 2 μm wavelength. This performance level in combination with GW-class peak power makes our laser source extremely interesting for driving high-harmonic generation or for generating mid-infrared frequency combs via intra-pulse frequency down-conversion at an unprecedented average power. The experiments were enabled by an ultrafast thulium-doped fiber laser delivering 110 fs pulses at high repetition rates, and an argon gas-filled antiresonant hollow-core fiber (ARHCF) with excellent transmission and weak anomalous dispersion, leading to the self-compression of the pulses. We have shown that ARHCFs are well-suited for nonlinear pulse compression around 2 μm wavelength and that this concept features excellent power handling capabilities. Based on this result, we discuss the next steps for energy and average power scaling including upscaling the fiber dimensions in order to fully exploit the capabilities of our laser system, which can deliver several GW of peak power. This way, a 100 W-class laser source with mJ-level few-cycle pulses at 2 μm wavelength is feasible in the near future.

Being everything to anyone: Applicability of thermoacoustic technology in the commercial refrigeration market

NASA Astrophysics Data System (ADS)

Poese, Matthew E.; Smith, Robert W. M.; Garrett, Steven L.

2005-09-01

This talk will compare electrodynamically driven thermoacoustic refrigeration technology to some common implementations of low-lift vapor-compression technology. A rudimentary explanation of vapor-compression refrigeration will be presented along with some of the implementation problems faced by refrigeration engineers using compressor-based systems. These problems include oil management, compressor slugging, refrigerant leaks and the environmental impact of refrigerants. Recently, the method of evaluating this environmental impact has been codified to include the direct effects of the refrigerants on global warming as well as the so-called ``indirect'' warming impact of the carbon dioxide released during the generation (at the power plant) of the electrical power consumed by the refrigeration equipment. It is issues like these that generate commercial interest in an alternative refrigeration technology. However, the requirements of a candidate technology for adoption in a mature and risk-averse commercial refrigeration industry are as hard to divine as they are to meet. Also mentioned will be the state of other alternative refrigeration technologies like free-piston Stirling, thermoelectric and magnetocaloric as well as progress using vapor compression technology with alternative refrigerants like hydrocarbons and carbon dioxide.

A Brief Study on Toxic Combustion Products of the Polymers Used in High-Pressure Oxygen Systems

NASA Technical Reports Server (NTRS)

Hshieh, Fu-Yu; Beeson, Harold D.

2005-01-01

One likely cause of polymer ignition in a high-pressure oxygen system is the adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper investigates the feasibility of using the NASA pneumatic-impact system to conduct adiabatic-compression combustion tests and determines the toxic combustion products produced from the burning of five selected polymers. Five polymers commonly used in high-pressure oxygen systems, Zytel(Registered TradeMark) 42 (Nylon 6/6), Buna N (nitrile rubber), Witon(Registered TradeMark) A (copolymer of vinylidene fluoride and hexafluoropropylene), Neoflon(Registered TradeMark) (polychlorotrifluoroethylene), and Teflon(Registered TradeMark) (polytetrafluoroethylene), were tested in the NASA pneumatic-impact test system at 17.2-MPa oxygen pressure. The polymers were ignited and burned; combustion products were collected in a stainless-steel sample bottle and analyzed using various methods. The results show that the NASA pneumatic-impact system is an appropriate test system to conduct adiabatic-compression combustion tests and to collect combustion products for further chemical analysis. The composition of the combustion product gas generated from burning the five selected polymers are presented and discussed.

Steady Secondary Flows Generated by Periodic Compression and Expansion of an Ideal Gas in a Pulse Tube

NASA Technical Reports Server (NTRS)

Lee, Jeffrey M.

1999-01-01

This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.

Development of iterative techniques for the solution of unsteady compressible viscous flows

NASA Technical Reports Server (NTRS)

Hixon, Duane; Sankar, L. N.

1993-01-01

During the past two decades, there has been significant progress in the field of numerical simulation of unsteady compressible viscous flows. At present, a variety of solution techniques exist such as the transonic small disturbance analyses (TSD), transonic full potential equation-based methods, unsteady Euler solvers, and unsteady Navier-Stokes solvers. These advances have been made possible by developments in three areas: (1) improved numerical algorithms; (2) automation of body-fitted grid generation schemes; and (3) advanced computer architectures with vector processing and massively parallel processing features. In this work, the GMRES scheme has been considered as a candidate for acceleration of a Newton iteration time marching scheme for unsteady 2-D and 3-D compressible viscous flow calculation; from preliminary calculations, this will provide up to a 65 percent reduction in the computer time requirements over the existing class of explicit and implicit time marching schemes. The proposed method has ben tested on structured grids, but is flexible enough for extension to unstructured grids. The described scheme has been tested only on the current generation of vector processor architecture of the Cray Y/MP class, but should be suitable for adaptation to massively parallel machines.

Investigation of unsteadiness in Shock-particle cloud interaction: Fully resolved two-dimensional simulation and one-dimensional modeling

NASA Astrophysics Data System (ADS)

Hosseinzadeh-Nik, Zahra; Regele, Jonathan D.

2015-11-01

Dense compressible particle-laden flow, which has a complex nature, exists in various engineering applications. Shock waves impacting a particle cloud is a canonical problem to investigate this type of flow. It has been demonstrated that large flow unsteadiness is generated inside the particle cloud from the flow induced by the shock passage. It is desirable to develop models for the Reynolds stress to capture the energy contained in vortical structures so that volume-averaged models with point particles can be simulated accurately. However, the previous work used Euler equations, which makes the prediction of vorticity generation and propagation innacurate. In this work, a fully resolved two dimensional (2D) simulation using the compressible Navier-Stokes equations with a volume penalization method to model the particles has been performed with the parallel adaptive wavelet-collocation method. The results still show large unsteadiness inside and downstream of the particle cloud. A 1D model is created for the unclosed terms based upon these 2D results. The 1D model uses a two-phase simple low dissipation AUSM scheme (TSLAU) developed by coupled with the compressible two phase kinetic energy equation.

Assessment of chemistry models for compressible reacting flows

NASA Astrophysics Data System (ADS)

Lapointe, Simon; Blanquart, Guillaume

2014-11-01

Recent technological advances in propulsion and power devices and renewed interest in the development of next generation supersonic and hypersonic vehicles have increased the need for detailed understanding of turbulence-combustion interactions in compressible reacting flows. In numerical simulations of such flows, accurate modeling of the fuel chemistry is a critical component of capturing the relevant physics. Various chemical models are currently being used in reacting flow simulations. However, the differences between these models and their impacts on the fluid dynamics in the context of compressible flows are not well understood. In the present work, a numerical code is developed to solve the fully coupled compressible conservation equations for reacting flows. The finite volume code is based on the theoretical and numerical framework developed by Oefelein (Prog. Aero. Sci. 42 (2006) 2-37) and employs an all-Mach-number formulation with dual time-stepping and preconditioning. The numerical approach is tested on turbulent premixed flames at high Karlovitz numbers. Different chemical models of varying complexity and computational cost are used and their effects are compared.

Parametric study on single shot peening by dimensional analysis method incorporated with finite element method

NASA Astrophysics Data System (ADS)

Wu, Xian-Qian; Wang, Xi; Wei, Yan-Peng; Song, Hong-Wei; Huang, Chen-Guang

2012-06-01

Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and resistance to corrosion fatigue, cracking, etc. Compressive residual stress and dent profile are important factors to evaluate the effectiveness of shot peening process. In this paper, the influence of dimensionless parameters on maximum compressive residual stress and maximum depth of the dent were investigated. Firstly, dimensionless relations of processing parameters that affect the maximum compressive residual stress and the maximum depth of the dent were deduced by dimensional analysis method. Secondly, the influence of each dimensionless parameter on dimensionless variables was investigated by the finite element method. Furthermore, related empirical formulas were given for each dimensionless parameter based on the simulation results. Finally, comparison was made and good agreement was found between the simulation results and the empirical formula, which shows that a useful approach is provided in this paper for analyzing the influence of each individual parameter.

Properties of three graphite/toughened resin composites

NASA Technical Reports Server (NTRS)

Smith, Donald L.; Dow, Marvin B.

1991-01-01

Results are presented from an experimental evaluation of IM7/977-2, IM7/F655, and T800/F3900. Data presented include ply-level (unidirectional laminate) strength and moduli, unnotched and notched (open hole) tension and compression properties of quasi-isotropic laminates, and compression-after-impact strengths. These data are compared with properties of other toughened (IM7/8551-7 and IM6/18081) and brittle (T300/5208) graphite-epoxy materials. The IM7/977-2, IM7/F655, and T800/F3900 materials are substantially stronger and more damage tolerant than widely used first generation composite materials such as T300/5208. The T800/F3900 outperforms IM7/977-2 and IM7/F655 materials in tolerance to projectile impacts. Compression-after-impact strengths were found to be dependent on impactor velocity for a given impact energy. The open hole compression properties of all three materials are degraded by the combination of heat and moisture.

Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

DOEpatents

Moore, David S.; Schmidt, Stephen C.

1985-01-01

A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

Compression of transmission bandwidth requirements for a certain class of band-limited functions.

NASA Technical Reports Server (NTRS)

Smith, I. R.; Schilling, D. L.

1972-01-01

A study of source-encoding techniques that afford a reduction of data-transmission rates is made with particular emphasis on the compression of transmission bandwidth requirements of band-limited functions. The feasibility of bandwidth compression through analog signal rooting is investigated. It is found that the N-th roots of elements of a certain class of entire functions of exponential type possess contour integrals resembling Fourier transforms, the Cauchy principal values of which are compactly supported on an interval one N-th the size of that of the original function. Exploring this theoretical result, it is found that synthetic roots can be generated, which closely approximate the N-th roots of a certain class of band-limited signals and possess spectra that are essentially confined to a bandwidth one N-th that of the signal subjected to the rooting operation. A source-encoding algorithm based on this principle is developed that allows the compression of data-transmission requirements for a certain class of band-limited signals.

Ultrafast visualization of crystallization and grain growth in shock-compressed SiO2

PubMed Central

Gleason, A. E.; Bolme, C. A.; Lee, H. J.; Nagler, B.; Galtier, E.; Milathianaki, D.; Hawreliak, J.; Kraus, R. G.; Eggert, J. H.; Fratanduono, D. E.; Collins, G. W.; Sandberg, R.; Yang, W.; Mao, W. L.

2015-01-01

Pressure- and temperature-induced phase transitions have been studied for more than a century but very little is known about the non-equilibrium processes by which the atoms rearrange. Shock compression generates a nearly instantaneous propagating high-pressure/temperature condition while in situ X-ray diffraction (XRD) probes the time-dependent atomic arrangement. Here we present in situ pump–probe XRD measurements on shock-compressed fused silica, revealing an amorphous to crystalline high-pressure stishovite phase transition. Using the size broadening of the diffraction peaks, the growth of nanocrystalline stishovite grains is resolved on the nanosecond timescale just after shock compression. At applied pressures above 18 GPa the nuclueation of stishovite appears to be kinetically limited to 1.4±0.4 ns. The functional form of this grain growth suggests homogeneous nucleation and attachment as the growth mechanism. These are the first observations of crystalline grain growth in the shock front between low- and high-pressure states via XRD. PMID:26337754

Computer-aided, multi-modal, and compression diffuse optical studies of breast tissue

NASA Astrophysics Data System (ADS)

Busch, David Richard, Jr.

Diffuse Optical Tomography and Spectroscopy permit measurement of important physiological parameters non-invasively through ˜10 cm of tissue. I have applied these techniques in measurements of human breast and breast cancer. My thesis integrates three loosely connected themes in this context: multi-modal breast cancer imaging, automated data analysis of breast cancer images, and microvascular hemodynamics of breast under compression. As per the first theme, I describe construction, testing, and the initial clinical usage of two generations of imaging systems for simultaneous diffuse optical and magnetic resonance imaging. The second project develops a statistical analysis of optical breast data from many spatial locations in a population of cancers to derive a novel optical signature of malignancy; I then apply this data-derived signature for localization of cancer in additional subjects. Finally, I construct and deploy diffuse optical instrumentation to measure blood content and blood flow during breast compression; besides optics, this research has implications for any method employing breast compression, e.g., mammography.

Finite element analysis of residual stress in cold expanded plate with different thickness and expansion ratio

NASA Astrophysics Data System (ADS)

Arifin Shariffudin, Kamarul; Karuppanan, Saravanan; Patil, Santosh S.

2017-10-01

Cold expansion of fastener/rivet holes is a common way to generate beneficial compressive residual stress around the fastener hole. In this study, cold expansion process was simulated by finite-element method in order to determine the residual stress field around two cold expanded holes by varying the plate thickness and expansion ratio of the hole. The model was developed in ANSYS and assigned to aluminium alloy 7475-T61 material model. The results showed that the residual stress become more compressive as the plate thickness is increased up to t/d = 2.6 and decreased for further level of thickness. In addition, the residual stress at the edge of the hole become more compressive as the expansion ratio is increased up to 4.5% and decreased for further level of expansion. This study also found that the residual stresses near the entrance and the exit face of the plate are less compressive than the residual stresses on the mid-thickness of the plate.

Ultrafast visualization of crystallization and grain growth in shock-compressed SiO 2

DOE PAGES

Gleason, A. E.; Bolme, C. A.; Lee, H. J.; ...

2015-09-04

Pressure- and temperature-induced phase transitions have been studied for more than a century but very little is known about the non-equilibrium processes by which the atoms rearrange. Shock compression generates a nearly instantaneous propagating high-pressure/temperature condition while in situ X-ray diffraction (XRD) probes the time-dependent atomic arrangement. Here we present in situ pump–probe XRD measurements on shock-compressed fused silica, revealing an amorphous to crystalline high-pressure stishovite phase transition. Using the size broadening of the diffraction peaks, the growth of nanocrystalline stishovite grains is resolved on the nanosecond timescale just after shock compression. At applied pressures above 18 GPa the nuclueationmore » of stishovite appears to be kinetically limited to 1.4 ± 0.4 ns. The functional form of this grain growth suggests homogeneous nucleation and attachment as the growth mechanism. As a result, these are the first observations of crystalline grain growth in the shock front between low- and high-pressure states via XRD.« less

Short intense ion pulses for materials and warm dense matter research

NASA Astrophysics Data System (ADS)

Seidl, Peter A.; Persaud, Arun; Waldron, William L.; Barnard, John J.; Davidson, Ronald C.; Friedman, Alex; Gilson, Erik P.; Greenway, Wayne G.; Grote, David P.; Kaganovich, Igor D.; Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas

2015-11-01

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 1010 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li+ ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

DOEpatents

Moore, D.S.; Schmidt, S.C.

1983-12-16

A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

Isentropic compression of liquid metals near the melt line

NASA Astrophysics Data System (ADS)

Seagle, Christopher; Porwitzky, Andrew

2017-06-01

A series of experiments designed to study the liquid metal response to isentropic compression have been conducted at Sandia's Z Pulsed Power Facility. Cerium and Tin have been shock melted by driving a quasi-ballistic flyer into the samples followed by a ramp compression wave generated by an increased driving magnetic field. The sound speed of the liquid metals has been investigated with the purpose of exploring possible solidification on ramp compression. Additional surface sensitive diagnostics have been employed to search for signatures of solidification at the window interface. Results of these experiments will be discussed in relation to the existing equation of state models and phase diagrams for these materials as well as future plans for exploring the response of liquid metals near the melt line. Sandia National Laboratories is a multi-mission 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.

A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray

NASA Astrophysics Data System (ADS)

Schiffer, A.; Gardner, M. N.; Lynn, R. H.; Tagarielli, V. L.

2017-03-01

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

Compressibility effect on thermal coherent structures in spatially-developing turbulent boundary layers via DNS

NASA Astrophysics Data System (ADS)

Araya, Guillermo; Jansen, Kenneth

2017-11-01

DNS of compressible spatially-developing turbulent boundary layers is performed at a Mach number of 2.5 over an isothermal flat plate. Turbulent inflow information is generated by following the concept of the rescaling-recycling approach introduced by Lund et al. (J. Comp. Phys. 140, 233-258, 1998); although, the proposed methodology is extended to compressible flows. Furthermore, a dynamic approach is employed to connect the friction velocities at the inlet and recycle stations (i.e., there is no need of an empirical correlation as in Lund et al.). Additionally, the Morkovin's Strong Reynolds Analogy (SRA) is used in the rescaling process of the thermal fluctuations from the recycle plane. Low/high order flow statistics is compared with direct simulations of an incompressible isothermal ZPG boundary layer at similar Reynolds numbers and temperature regarded as a passive scalar. Focus is given to the effect assessment of flow compressibility on the dynamics of thermal coherent structures. AFOSR #FA9550-17-1-0051.

Preparation of delayed release tablet dosage forms by compression coating: effect of coating material on theophylline release.

PubMed

El-Malah, Yasser; Nazzal, Sami

2010-06-01

In this study, compression-coated tablets were prepared and examined by real-time swelling/erosion analysis and dissolution studies. Of the coating materials, PVP showed no swelling behavior and had no impact on theophylline release. Polyox(®) exhibited swelling behavior of an entangled polymer, which was reflected in its > 14-hour delayed-release profile. Hydroxypropyl methylcellulose (HPMC), which revealed the characteristics of a disentangled polymer, caused a 2-h delay in theophylline release. Based on preliminary texture analysis data, Polyox(®)/PVP blends were used as coating materials to manipulate the onset of drug release from the compression-coated tablets. Of the blends, at a 1:1 ratio, for example, resulted in a burst release after 10 h, which demonstrated the feasibility of preparing delayed release dosage forms by compression coating. Furthermore, it was feasible to predict the dissolution behavior of polymers from their swelling/erosion data, which were generated from texture analysis.

Enabling IP Header Compression in COTS Routers via Frame Relay on a Simplex Link

NASA Technical Reports Server (NTRS)

Nguyen, Sam P.; Pang, Jackson; Clare, Loren P.; Cheng, Michael K.

2010-01-01

NASA is moving toward a networkcentric communications architecture and, in particular, is building toward use of Internet Protocol (IP) in space. The use of IP is motivated by its ubiquitous application in many communications networks and in available commercial off-the-shelf (COTS) technology. The Constellation Program intends to fit two or more voice (over IP) channels on both the forward link to, and the return link from, the Orion Crew Exploration Vehicle (CEV) during all mission phases. Efficient bandwidth utilization of the links is key for voice applications. In Voice over IP (VoIP), the IP packets are limited to small sizes to keep voice latency at a minimum. The common voice codec used in VoIP is G.729. This new algorithm produces voice audio at 8 kbps and in packets of 10-milliseconds duration. Constellation has designed the VoIP communications stack to use the combination of IP/UDP/RTP protocols where IP carries a 20-byte header, UDP (User Datagram Protocol) carries an 8-byte header, and RTP (Real Time Transport Protocol) carries a 12-byte header. The protocol headers total 40 bytes and are equal in length to a 40-byte G.729 payload, doubling the VoIP latency. Since much of the IP/UDP/RTP header information does not change from IP packet to IP packet, IP/UDP/RTP header compression can avoid transmission of much redundant data as well as reduce VoIP latency. The benefits of IP header compression are more pronounced at low data rate links such as the forward and return links during CEV launch. IP/UDP/RTP header compression codecs are well supported by many COTS routers. A common interface to the COTS routers is through frame relay. However, enabling IP header compression over frame relay, according to industry standard (Frame Relay IP Header Compression Agreement FRF.20), requires a duplex link and negotiations between the compressor router and the decompressor router. In Constellation, each forward to and return link from the CEV in space is treated independently as a simplex link. Without negotiation, the COTS routers are prevented from entering into the IP header compression mode, and no IP header compression would be performed. An algorithm is proposed to enable IP header compression in COTS routers on a simplex link with no negotiation or with a one-way messaging. In doing so, COTS routers can enter IP header compression mode without the need to handshake through a bidirectional link as required by FRF.20. This technique would spoof the routers locally and thereby allow the routers to enter into IP header compression mode without having the negotiations between routers actually occur. The spoofing function is conducted by a frame relay adapter (also COTS) with the capability to generate control messages according to the FRF.20 descriptions. Therefore, negotiation is actually performed between the FRF.20 adapter and the connecting COTS router locally and never occurs over the space link. Through understanding of the handshaking protocol described by FRF.20, the necessary FRF.20 negotiations messages can be generated to control the connecting router, not only to turn on IP header compression but also to adjust the compression parameters. The FRF.20 negotiation (or control) message is composed in the FRF.20 adapter by interpreting the incoming router request message. Many of the fields are simply transcribed from request to response while the control field indicating response and type are modified.

Compressed Secret Key Agreement:Maximizing Multivariate Mutual Information per Bit

NASA Astrophysics Data System (ADS)

Chan, Chung

2017-10-01

The multiterminal secret key agreement problem by public discussion is formulated with an additional source compression step where, prior to the public discussion phase, users independently compress their private sources to filter out strongly correlated components for generating a common secret key. The objective is to maximize the achievable key rate as a function of the joint entropy of the compressed sources. Since the maximum achievable key rate captures the total amount of information mutual to the compressed sources, an optimal compression scheme essentially maximizes the multivariate mutual information per bit of randomness of the private sources, and can therefore be viewed more generally as a dimension reduction technique. Single-letter lower and upper bounds on the maximum achievable key rate are derived for the general source model, and an explicit polynomial-time computable formula is obtained for the pairwise independent network model. In particular, the converse results and the upper bounds are obtained from those of the related secret key agreement problem with rate-limited discussion. A precise duality is shown for the two-user case with one-way discussion, and such duality is extended to obtain the desired converse results in the multi-user case. In addition to posing new challenges in information processing and dimension reduction, the compressed secret key agreement problem helps shed new light on resolving the difficult problem of secret key agreement with rate-limited discussion, by offering a more structured achieving scheme and some simpler conjectures to prove.

Optimal Compressed Sensing and Reconstruction of Unstructured Mesh Datasets

DOE PAGES

Salloum, Maher; Fabian, Nathan D.; Hensinger, David M.; ...

2017-08-09

Exascale computing promises quantities of data too large to efficiently store and transfer across networks in order to be able to analyze and visualize the results. We investigate compressed sensing (CS) as an in situ method to reduce the size of the data as it is being generated during a large-scale simulation. CS works by sampling the data on the computational cluster within an alternative function space such as wavelet bases and then reconstructing back to the original space on visualization platforms. While much work has gone into exploring CS on structured datasets, such as image data, we investigate itsmore » usefulness for point clouds such as unstructured mesh datasets often found in finite element simulations. We sample using a technique that exhibits low coherence with tree wavelets found to be suitable for point clouds. We reconstruct using the stagewise orthogonal matching pursuit algorithm that we improved to facilitate automated use in batch jobs. We analyze the achievable compression ratios and the quality and accuracy of reconstructed results at each compression ratio. In the considered case studies, we are able to achieve compression ratios up to two orders of magnitude with reasonable reconstruction accuracy and minimal visual deterioration in the data. Finally, our results suggest that, compared to other compression techniques, CS is attractive in cases where the compression overhead has to be minimized and where the reconstruction cost is not a significant concern.« less

TU-CD-207-09: Analysis of the 3-D Shape of Patients’ Breast for Breast Imaging and Surgery Planning

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

Agasthya, G; Sechopoulos, I

2015-06-15

Purpose: Develop a method to accurately capture the 3-D shape of patients’ external breast surface before and during breast compression for mammography/tomosynthesis. Methods: During this IRB-approved, HIPAA-compliant study, 50 women were recruited to undergo 3-D breast surface imaging during breast compression and imaging for the cranio-caudal (CC) view on a digital mammography/breast tomosynthesis system. Digital projectors and cameras mounted on tripods were used to acquire 3-D surface images of the breast, in three conditions: (a) positioned on the support paddle before compression, (b) during compression by the compression paddle and (c) the anterior-posterior view with the breast in its natural,more » unsupported position. The breast was compressed to standard full compression with the compression paddle and a tomosynthesis image was acquired simultaneously with the 3-D surface. The 3-D surface curvature and deformation with respect to the uncompressed surface was analyzed using contours. The 3-D surfaces were voxelized to capture breast shape in a format that can be manipulated for further analysis. Results: A protocol was developed to accurately capture the 3-D shape of patients’ breast before and during compression for mammography. Using a pair of 3-D scanners, the 50 patient breasts were scanned in three conditions, resulting in accurate representations of the breast surfaces. The surfaces were post processed, analyzed using contours and voxelized, with 1 mm{sup 3} voxels, converting the breast shape into a format that can be easily modified as required. Conclusion: Accurate characterization of the breast curvature and shape for the generation of 3-D models is possible. These models can be used for various applications such as improving breast dosimetry, accurate scatter estimation, conducting virtual clinical trials and validating compression algorithms. Ioannis Sechopoulos is consultant for Fuji Medical Systems USA.« less

Curvelet-based compressive sensing for InSAR raw data

NASA Astrophysics Data System (ADS)

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, therefore, providing a feasibility for compressive sensing application.

Anomalous compression behavior of ˜12 nm nanocrystalline TiO2

NASA Astrophysics Data System (ADS)

Wang, Qiming; Li, Shourui; Peng, Fang; Lei, Li; Hu, Qiwei; Wang, Pei; Nan, Xiaolong; Liu, Jing; Zhu, Wenjun; He, Duanwei

2017-06-01

When the grain size decreases, there inevitably exists a critical size (dc) where the contribution of surface atoms to the physical properties is competitive with that of the interior atoms, giving rise to a wide variety of new phenomena. The behavior of granular materials near dc is particularly interesting because of the crossover, a continuous transition from one type of mechanism to another. In situ high-pressure x-ray diffraction experiments showed that the compression curve of nanocrystalline anatase TiO2 with grain size near dc reached a platform after about 5%-6% of deformation under hydrostatic compression. Eventually, the unit cell volume of anatase expanded at ˜14-16 GPa. We propose that the anomalous compression behavior is attributed to the formation and thickening of the stiff high density amorphous shell under high pressure, giving rise to a great arching effect at the grain boundary at the nanolevel. This process results in a remarkable difference in stress between inside and outside of the shell, generating the illusions of the hardening and the negative compressibility. This study offers a new insight into the mechanical properties of nanomaterials under extreme conditions.

Super-tough, ultra-stretchable and strongly compressive hydrogels with core-shell latex particles inducing efficient aggregation of hydrophobic chains.

PubMed

Ren, Xiuyan; Huang, Chang; Duan, Lijie; Liu, Baijun; Bu, Lvjun; Guan, Shuang; Hou, Jiliang; Zhang, Huixuan; Gao, Guanghui

2017-05-14

Toughness, strechability and compressibility for hydrogels were ordinarily balanced for their use as mechanically responsive materials. For example, macromolecular microsphere composite hydrogels with chemical crosslinking exhibited excellent compression strength and strechability, but poor tensile stress. Here, a novel strategy for the preparation of a super-tough, ultra-stretchable and strongly compressive hydrogel was proposed by introducing core-shell latex particles (LPs) as crosslinking centers for inducing efficient aggregation of hydrophobic chains. The core-shell LPs always maintained a spherical shape due to the presence of a hard core even by an external force and the soft shell could interact with hydrophobic chains due to hydrophobic interactions. As a result, the hydrogels reinforced by core-shell LPs exhibited not only a high tensile strength of 1.8 MPa and dramatic elongation of over 20 times, but also an excellent compressive performance of 13.5 MPa at a strain of 90%. The Mullins effect was verified for the validity of core-shell LP-reinforced hydrogels by inducing aggregation of hydrophobic chains. The novel strategy strives to provide a better avenue for designing and developing a new generation of hydrophobic association tough hydrogels with excellent mechanical properties.

Verification of conventional equations of state for tantalum under quasi-isentropic compression

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

Binqiang, Luo; Guiji, Wang; Jianjun, Mo

2014-11-21

Shock Hugoniot data have been widely used to calibrate analytic equations of state (EOSs) of condensed matter at high pressures. However, the suitability of particular analytic EOSs under off-Hugoniot states has not been sufficiently verified using experimental data. We have conducted quasi-isentropic compression experiments (ICEs) of tantalum using the compact pulsed power generator CQ-4, and explored the relation of longitudinal stress versus volume of tantalum under quasi-isentropic compression using backward integration and characteristic inverse methods. By subtracting the deviatoric stress and additional pressure caused by irreversible plastic dissipation, the isentropic pressure can be extracted from the longitudinal stress. Several theoreticalmore » isentropes are deduced from analytic EOSs and compared with ICE results to validate the suitability of these analytic EOSs in isentropic compression states. The comparisons show that the Gruneisen EOS with Gruneisen Gamma proportional to volume is accurate, regardless whether the Hugoniot or isentrope is used as the reference line. The Vinet EOS yields better accuracy in isentropic compression states. Theoretical isentropes derived from Tillotson, PUFF, and Birch-Murnaghan EOSs well agree with the experimental isentrope in the range of 0–100 GPa, but deviate gradually with pressure increasing further.« less

Reconstruction of Complex Network based on the Noise via QR Decomposition and Compressed Sensing.

PubMed

Li, Lixiang; Xu, Dafei; Peng, Haipeng; Kurths, Jürgen; Yang, Yixian

2017-11-08

It is generally known that the states of network nodes are stable and have strong correlations in a linear network system. We find that without the control input, the method of compressed sensing can not succeed in reconstructing complex networks in which the states of nodes are generated through the linear network system. However, noise can drive the dynamics between nodes to break the stability of the system state. Therefore, a new method integrating QR decomposition and compressed sensing is proposed to solve the reconstruction problem of complex networks under the assistance of the input noise. The state matrix of the system is decomposed by QR decomposition. We construct the measurement matrix with the aid of Gaussian noise so that the sparse input matrix can be reconstructed by compressed sensing. We also discover that noise can build a bridge between the dynamics and the topological structure. Experiments are presented to show that the proposed method is more accurate and more efficient to reconstruct four model networks and six real networks by the comparisons between the proposed method and only compressed sensing. In addition, the proposed method can reconstruct not only the sparse complex networks, but also the dense complex networks.

Survey Of Lossless Image Coding Techniques

NASA Astrophysics Data System (ADS)

Melnychuck, Paul W.; Rabbani, Majid

1989-04-01

Many image transmission/storage applications requiring some form of data compression additionally require that the decoded image be an exact replica of the original. Lossless image coding algorithms meet this requirement by generating a decoded image that is numerically identical to the original. Several lossless coding techniques are modifications of well-known lossy schemes, whereas others are new. Traditional Markov-based models and newer arithmetic coding techniques are applied to predictive coding, bit plane processing, and lossy plus residual coding. Generally speaking, the compression ratio offered by these techniques are in the area of 1.6:1 to 3:1 for 8-bit pictorial images. Compression ratios for 12-bit radiological images approach 3:1, as these images have less detailed structure, and hence, their higher pel correlation leads to a greater removal of image redundancy.

Compressible Navier-Stokes Equations in a Polyhedral Cylinder with Inflow Boundary Condition

NASA Astrophysics Data System (ADS)

Kwon, Ohsung; Kweon, Jae Ryong

2018-06-01

In this paper our concern is with singularity and regularity of the compressible flows through a non-convex edge in R^3. The flows are governed by the compressible Navies-Stokes equations on the infinite cylinder that has the non-convex edge on the inflow boundary. We split the edge singularity by the Poisson problem from the velocity vector and show that the remainder is twice differentiable while the edge singularity is observed to be propagated into the interior of the cylinder by the transport character of the continuity equation. An interior surface layer starting at the edge is generated and not Lipshitz continuous due to the singularity. The density function shows a very steep change near the interface and its normal derivative has a jump discontinuity across there.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, T.

1998-06-16

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell. 5 figs.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, Tomas

1998-01-01

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.

Apparatus and method of preloading vibration-damping bellows

DOEpatents

Cutburth, Ronald W.

1988-01-01

An improved vibration damping bellows mount or interconnection is disclosed. In one aspect, the bellows is compressively prestressed along its length to offset vacuum-generated tensile loads and thereby improve vibration damping characteristics.

New methods of generation of ultrashort laser pulses for ranging

NASA Technical Reports Server (NTRS)

Jelinkova, Helena; Hamal, Karel; Kubecek, V.; Prochazka, Ivan

1993-01-01

To reach the millimeter satellite laser ranging accuracy, the goal for nineties, new laser ranging techniques have to be applied. To increase the laser ranging precision, the application of the ultrashort laser pulses in connection with the new signal detection and processing techniques, is inevitable. The two wavelength laser ranging is one of the ways to measure the atmospheric dispersion to improve the existing atmospheric correction models and hence, to increase the overall system ranging accuracy to the desired value. We are presenting a review of several nonstandard techniques of ultrashort laser pulses generation, which may be utilized for laser ranging: compression of the nanosecond pulses using stimulated Brillouin and Raman backscattering; compression of the mode-locked pulses using Raman backscattering; passive mode-locking technique with nonlinear mirror; and passive mode-locking technique with the negative feedback.

Generation of magneto-immersed electron beams

NASA Astrophysics Data System (ADS)

Pikin, A.; Raparia, D.

2018-05-01

There are many applications of electron beams in accelerator facilities: for electron coolers, electron lenses, and electron beam ion sources (EBIS) to mention a few. Most of these applications require magnetic compression of the electron beam to reduce the beam radius with the goal of either matching the circulating ion beam (electron lenses and electron coolers) or increasing the ionization capability for the production of highly charged ions (EBIS). The magnetic compression of the electron beam comes at a cost of increasing share of the transverse component of energy and therefore increased angles of the electron trajectories to the longitudinal axis. Considering the effect of the magnetic mirror, it is highly desirable to produce a laminar electron beam in the electron gun. The analysis of electron guns with different configurations is given in this paper with emphasis on generating laminar electron beams.

A fast sequence assembly method based on compressed data structures.

PubMed

Liang, Peifeng; Zhang, Yancong; Lin, Kui; Hu, Jinglu

2014-01-01

Assembling a large genome using next generation sequencing reads requires large computer memory and a long execution time. To reduce these requirements, a memory and time efficient assembler is presented from applying FM-index in JR-Assembler, called FMJ-Assembler, where FM stand for FMR-index derived from the FM-index and BWT and J for jumping extension. The FMJ-Assembler uses expanded FM-index and BWT to compress data of reads to save memory and jumping extension method make it faster in CPU time. An extensive comparison of the FMJ-Assembler with current assemblers shows that the FMJ-Assembler achieves a better or comparable overall assembly quality and requires lower memory use and less CPU time. All these advantages of the FMJ-Assembler indicate that the FMJ-Assembler will be an efficient assembly method in next generation sequencing technology.

Thermal stress control using waste steel fibers in massive concretes

NASA Astrophysics Data System (ADS)

Sarabi, Sahar; Bakhshi, Hossein; Sarkardeh, Hamed; Nikoo, Hamed Safaye

2017-11-01

One of the important subjects in massive concrete structures is the control of the generated heat of hydration and consequently the potential of cracking due to the thermal stress expansion. In the present study, using the waste turnery steel fibers in the massive concretes, the amount of used cement was reduced without changing the compressive strength. By substituting a part of the cement with waste steel fibers, the costs and the generated hydration heat were reduced and the tensile strength was increased. The results showed that by using 0.5% turnery waste steel fibers and consequently, reducing to 32% the cement content, the hydration heat reduced to 23.4% without changing the compressive strength. Moreover, the maximum heat gradient reduced from 18.5% in the plain concrete sample to 12% in the fiber-reinforced concrete sample.

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Astrophysics Data System (ADS)

Barrie, A.; Adrian, M. L.; Yeh, P.; Winkert, G.; Lobell, J.; Vinas, A. F.; Simpson, D. G.

2009-12-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6° x 180° fields-of-view (FOV) are set 90° apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° x 180° fan about the its nominal viewing (0° deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 6.6-Mb s-1. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mb s-1. Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present updated simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data as well as the FPI-DIS ion data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements and Cluster/CIS ion measurements. Topics to be discussed include: (i) Review of compression algorithm; (ii) Data quality; (iii) Data formatting/organization; (iv) Compression optimization; (v) Investigation of pseudo-log precompression; and (vi) Analysis of compression effectiveness for burst mode as well as fast survey mode data packets for both electron and ion data We conclude with a presentation of the current base-lined FPI data compression approach.

Performance Prediction and Simulation of Gas Turbine Engine Operation for Aircraft, Marine, Vehicular, and Power Generation

DTIC Science & Technology

2007-02-01

gas turbine systems is the Brayton cycle that passes atmospheric air, the working fluid, through the turbine only once. The thermodynamic steps of the... Brayton cycle include compression of atmospheric air, introduction and ignition of fuel, and expansion of the heated combustion gases through the...the two heat recovery steam generators to generate steam. The gas turbine model is built by connecting the individual components of the Brayton

Experimental characterization and constitutive modeling of the mechanical behavior of molybdenum under electromagnetically applied compression-shear ramp loading

DOE PAGES

Alexander, C. Scott; Ding, Jow -Lian; Asay, James Russell

2016-03-09

Magnetically applied pressure-shear (MAPS) is a new experimental technique that provides a platform for direct measurement of material strength at extreme pressures. The technique employs an imposed quasi-static magnetic field and a pulsed power generator that produces an intense current on a planar driver panel, which in turn generates high amplitude magnetically induced longitudinal compression and transverse shear waves into a planar sample mounted on the drive panel. In order to apply sufficiently high shear traction to the test sample, a high strength material must be used for the drive panel. Molybdenum is a potential driver material for the MAPSmore » experiment because of its high yield strength and sufficient electrical conductivity. To properly interpret the results and gain useful information from the experiments, it is critical to have a good understanding and a predictive capability of the mechanical response of the driver. In this work, the inelastic behavior of molybdenum under uniaxial compression and biaxial compression-shear ramp loading conditions is experimentally characterized. It is observed that an imposed uniaxial magnetic field ramped to approximately 10 T through a period of approximately 2500 μs and held near the peak for about 250 μs before being tested appears to anneal the molybdenum panel. In order to provide a physical basis for model development, a general theoretical framework that incorporates electromagnetic loading and the coupling between the imposed field and the inelasticity of molybdenum was developed. Based on this framework, a multi-axial continuum model for molybdenum under electromagnetic loading is presented. The model reasonably captures all of the material characteristics displayed by the experimental data obtained from various experimental configurations. Additionally, data generated from shear loading provide invaluable information not only for validating but also for guiding the development of the material model for multiaxial loadings.« less

A Numerical Simulation of a Normal Sonic Jet into a Hypersonic Cross-Flow

NASA Technical Reports Server (NTRS)

Jeffries, Damon K.; Krishnamurthy, Ramesh; Chandra, Suresh

1997-01-01

This study involves numerical modeling of a normal sonic jet injection into a hypersonic cross-flow. The numerical code used for simulation is GASP (General Aerodynamic Simulation Program.) First the numerical predictions are compared with well established solutions for compressible laminar flow. Then comparisons are made with non-injection test case measurements of surface pressure distributions. Good agreement with the measurements is observed. Currently comparisons are underway with the injection case. All the experimental data were generated at the Southampton University Light Piston Isentropic Compression Tube.

Effects of Ultrasonic Nanocrystal Surface Modification on the Residual Stress, Microstructure, and Corrosion Resistance of 304 Stainless Steel Welds

NASA Astrophysics Data System (ADS)

Ye, Chang; Telang, Abhishek; Gill, Amrinder; Wen, Xingshuo; Mannava, Seetha R.; Qian, Dong; Vasudevan, Vijay K.

2018-03-01

In this study, ultrasonic nanocrystal surface modification (UNSM) of 304 stainless steel welds was carried out. UNSM effectively eliminates the tensile stress generated during welding and imparts beneficial compressive residual stresses. In addition, UNSM can effectively refine the grains and increase hardness in the near-surface region. Corrosion tests in boiling MgCl2 solution demonstrate that UNSM can significantly improve the corrosion resistance due to the compressive residual stresses and changes in the near-surface microstructure.

THE EFFECT OF LASER SHOCK PEENING ON THE LIFE AND FAILURE MODE OF A COLD PILGER DIE

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

Lavender, Curt A.; Hong, Sung-tae; Smith, Mark T.

2008-08-11

The laser shock peening process was used to increase fatigue life of pilger dies made of A2 tool steel by imparting compressive residual stresses to fatigue prone areas of the dies. The result of X-Ray diffraction analysis indicated that deep, high- magnitude compressive residual stresses were generated by the laser shock peening process, and the peened dies exhibited a significant increase of in-service life. Fractography of the failed dies indicates that the fracture mechanism was altered by the peening process.

Evaluation of relative effects of carbohydrate sources in yeast-fermentation CO2 generators on mosquito surveillance

USDA-ARS?s Scientific Manuscript database

In order to collect mosquitoes in remote locations that do not have access to attractive lures, such as CO2 (i.e., dry ice or compressed gas), a natural method to generate CO2 on-site has been developed. Our research explored alternative sugar sources such as honey, molasses, and granulated sugar u...

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Astrophysics Data System (ADS)

Barrie, A. C.; Adrian, M. L.; Yeh, P.; Winkert, G. E.; Lobell, J. V.; Viňas, A. F.; Simpson, D. G.; Moore, T. E.

2008-12-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6° × 180° fields-of-view (FOV) are set 90° apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° × 180° fan about the its nominal viewing (0° deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 7.6-Mb s-1. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mb s-1. Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm- based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re- processed Cluster/PEACE electron measurements. Topics to be discussed include: (i) Review of compression algorithm; (ii) Data quality; (iii) Data formatting/organization; (iv) Compression optimization; and (v) Implications for data/matrix pruning. We conclude with a presentation of the base-lined FPI data compression approach.

Nonlinear model for offline correction of pulmonary waveform generators.

PubMed

Reynolds, Jeffrey S; Stemple, Kimberly J; Petsko, Raymond A; Ebeling, Thomas R; Frazer, David G

2002-12-01

Pulmonary waveform generators consisting of motor-driven piston pumps are frequently used to test respiratory-function equipment such as spirometers and peak expiratory flow (PEF) meters. Gas compression within these generators can produce significant distortion of the output flow-time profile. A nonlinear model of the generator was developed along with a method to compensate for gas compression when testing pulmonary function equipment. The model and correction procedure were tested on an Assess Full Range PEF meter and a Micro DiaryCard PEF meter. The tests were performed using the 26 American Thoracic Society standard flow-time waveforms as the target flow profiles. Without correction, the pump loaded with the higher resistance Assess meter resulted in ten waveforms having a mean square error (MSE) higher than 0.001 L2/s2. Correction of the pump for these ten waveforms resulted in a mean decrease in MSE of 87.0%. When loaded with the Micro DiaryCard meter, the uncorrected pump outputs included six waveforms with MSE higher than 0.001 L2/s2. Pump corrections for these six waveforms resulted in a mean decrease in MSE of 58.4%.

Turbulence generation through intense localized sources of energy

NASA Astrophysics Data System (ADS)

Maqui, Agustin; Donzis, Diego

2015-11-01

Mechanisms to generate turbulence in controlled conditions have been studied for nearly a century. Most common methods include passive and active grids with a focus on incompressible turbulence. However, little attention has been given to compressible flows, and even less to hypersonic flows, where phenomena such as thermal non-equilibrium can be present. Using intense energy from lasers, extreme molecule velocities can be generated from photo-dissociation. This creates strong localized changes in both the hydrodynamics and thermodynamics of the flow, which may perturb the flow in a way similar to an active grid to generate turbulence in hypersonic flows. A large database of direct numerical simulations (DNS) are used to study the feasibility of such an approach. An extensive analysis of single and two point statistics, as well as spectral dynamics is used to characterize the evolution of the flow towards realistic turbulence. Local measures of enstrophy and dissipation are studied to diagnose the main mechanisms for energy exchange. As commonly done in compressible flows, dilatational and solenoidal components are separated to understand the effect of acoustics on the development of turbulence. Further results for cases that assimilate laboratory conditions will be discussed. The authors gratefully acknowledge the support of AFOSR.

Three key regimes of single pulse generation per round trip of all-normal-dispersion fiber lasers mode-locked with nonlinear polarization rotation.

PubMed

Smirnov, Sergey; Kobtsev, Sergey; Kukarin, Sergey; Ivanenko, Aleksey

2012-11-19

We show experimentally and numerically new transient lasing regime between stable single-pulse generation and noise-like generation. We characterize qualitatively all three regimes of single pulse generation per round-trip of all-normal-dispersion fiber lasers mode-locked due to effect of nonlinear polarization evolution. We study spectral and temporal features of pulses produced in all three regimes as well as compressibility of such pulses. Simple criteria are proposed to identify lasing regime in experiment.

Plasma Studies in the SPECTOR Experiment as Target Development for MTF

NASA Astrophysics Data System (ADS)

Ivanov, Russ; Young, William; the Fusion Team, General

2016-10-01

General Fusion (GF) is developing a Magnetized Target Fusion (MTF) concept in which magnetized plasmas are adiabatically compressed to fusion conditions by the collapse of a liquid metal vortex. To study and optimize the plasma compression process, GF has a field test program in which subscale plasma targets are rapidly compressed with a moving flux conserver. GF has done many field tests to date on plasmas with sufficient thermal confinement but with a compression geometry that is not nearly self-similar. GF has a new design for our subscale plasma injectors called SPECTOR (for SPhErical Compact TORoid) capable of generating and compressing plasmas with a more spherical form factor. SPECTOR forms spherical tokamak plasmas by coaxial helicity injection into a flux conserver (a = 9 cm, R = 19 cm) with a pre-existing toroidal field created by 0.5 MA current in an axial shaft. The toroidal plasma current of 100 - 300 kA resistively decays over a time period of 1.5 msec. SPECTOR1 has an extensive set of plasma diagnostics including Thomson scattering and polarimetry. MHD stability and lifetime of the plasma was explored in different magnetic configurations with a variable safety factor q(Ψ) . Relatively hot (Te >= 350 eV) and dense ( 1020 m-3) plasmas have achieved energy confinement times τE >= 100 μsec and are now ready for field compression tests. russ.ivanov@generalfusion.com.

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

Salloum, Maher; Fabian, Nathan D.; Hensinger, David M.

Exascale computing promises quantities of data too large to efficiently store and transfer across networks in order to be able to analyze and visualize the results. We investigate compressed sensing (CS) as an in situ method to reduce the size of the data as it is being generated during a large-scale simulation. CS works by sampling the data on the computational cluster within an alternative function space such as wavelet bases and then reconstructing back to the original space on visualization platforms. While much work has gone into exploring CS on structured datasets, such as image data, we investigate itsmore » usefulness for point clouds such as unstructured mesh datasets often found in finite element simulations. We sample using a technique that exhibits low coherence with tree wavelets found to be suitable for point clouds. We reconstruct using the stagewise orthogonal matching pursuit algorithm that we improved to facilitate automated use in batch jobs. We analyze the achievable compression ratios and the quality and accuracy of reconstructed results at each compression ratio. In the considered case studies, we are able to achieve compression ratios up to two orders of magnitude with reasonable reconstruction accuracy and minimal visual deterioration in the data. Finally, our results suggest that, compared to other compression techniques, CS is attractive in cases where the compression overhead has to be minimized and where the reconstruction cost is not a significant concern.« less

Lightweight SIP/SDP compression scheme (LSSCS)

NASA Astrophysics Data System (ADS)

Wu, Jian J.; Demetrescu, Cristian

2001-10-01

In UMTS new IP based services with tight delay constraints will be deployed over the W-CDMA air interface such as IP multimedia and interactive services. To integrate the wireline and wireless IP services, 3GPP standard forum adopted the Session Initiation Protocol (SIP) as the call control protocol for the UMTS Release 5, which will implement next generation, all IP networks for real-time QoS services. In the current form the SIP protocol is not suitable for wireless transmission due to its large message size which will need either a big radio pipe for transmission or it will take far much longer to transmit than the current GSM Call Control (CC) message sequence. In this paper we present a novel compression algorithm called Lightweight SIP/SDP Compression Scheme (LSSCS), which acts at the SIP application layer and therefore removes the information redundancy before it is sent to the network and transport layer. A binary octet-aligned header is added to the compressed SIP/SDP message before sending it to the network layer. The receiver uses this binary header as well as the pre-cached information to regenerate the original SIP/SDP message. The key features of the LSSCS compression scheme are presented in this paper along with implementation examples. It is shown that this compression algorithm makes SIP transmission efficient over the radio interface without losing the SIP generality and flexibility.

Femtosecond wavelength tunable semiconductor optical amplifier fiber laser mode-locked by backward dark-optical-comb injection at 10 GHz.

PubMed

Lin, Gong-Ru; Chiu, I-Hsiang

2005-10-31

Femtosecond nonlinear pulse compression of a wavelength-tunable, backward dark-optical-comb injection harmonic-mode-locked semiconductor optical amplifier based fiber laser (SOAFL) is demonstrated for the first time. Shortest mode-locked SOAFL pulsewidth of 15 ps at 1 GHz is generated, which can further be compressed to 180 fs after linear chirp compensation, nonlinear soliton compression, and birefringent filtering. A maximum pulsewidth compression ratio for the compressed eighth-order SOAFL soliton of up to 80 is reported. The pedestal-free eighth-order soliton can be obtained by injecting the amplified pulse with peak power of 51 W into a 107.5m-long single-mode fiber (SMF), providing a linewidth and time-bandwidth product of 13.8 nm and 0.31, respectively. The tolerance in SMF length is relatively large (100-300 m) for obtaining <200fs SOAFL pulsewidth at wavelength tuning range of 1530-1560 nm. By extending the repetition frequency of dark-optical-comb up to 10 GHz, the mode-locked SOAFL pulsewidth can be slightly shortened from 5.4 ps to 3.9 ps after dispersion compensating, and further to 560 fs after second-order soliton compression. The lasing linewidth, time-bandwidth product and pulsewidth suppressing ratio of the SOAFL soliton become 4.5 nm, 0.33, and 10, respectively.

Wavelet compression techniques for hyperspectral data

NASA Technical Reports Server (NTRS)

Evans, Bruce; Ringer, Brian; Yeates, Mathew

1994-01-01

Hyperspectral sensors are electro-optic sensors which typically operate in visible and near infrared bands. Their characteristic property is the ability to resolve a relatively large number (i.e., tens to hundreds) of contiguous spectral bands to produce a detailed profile of the electromagnetic spectrum. In contrast, multispectral sensors measure relatively few non-contiguous spectral bands. Like multispectral sensors, hyperspectral sensors are often also imaging sensors, measuring spectra over an array of spatial resolution cells. The data produced may thus be viewed as a three dimensional array of samples in which two dimensions correspond to spatial position and the third to wavelength. Because they multiply the already large storage/transmission bandwidth requirements of conventional digital images, hyperspectral sensors generate formidable torrents of data. Their fine spectral resolution typically results in high redundancy in the spectral dimension, so that hyperspectral data sets are excellent candidates for compression. Although there have been a number of studies of compression algorithms for multispectral data, we are not aware of any published results for hyperspectral data. Three algorithms for hyperspectral data compression are compared. They were selected as representatives of three major approaches for extending conventional lossy image compression techniques to hyperspectral data. The simplest approach treats the data as an ensemble of images and compresses each image independently, ignoring the correlation between spectral bands. The second approach transforms the data to decorrelate the spectral bands, and then compresses the transformed data as a set of independent images. The third approach directly generalizes two-dimensional transform coding by applying a three-dimensional transform as part of the usual transform-quantize-entropy code procedure. The algorithms studied all use the discrete wavelet transform. In the first two cases, a wavelet transform coder was used for the two-dimensional compression. The third case used a three dimensional extension of this same algorithm.

Pulse compression of harmonic chirp signals using the fractional fourier transform.

PubMed

Arif, M; Cowell, D M J; Freear, S

2010-06-01

In ultrasound harmonic imaging with chirp-coded excitation, a harmonic matched filter (HMF) is typically used on the received signal to perform pulse compression of the second harmonic component (SHC) to recover signal axial resolution. Designing the HMF for the compression of the SHC is a problematic issue because it requires optimal window selection. In the compressed second harmonic signal, the sidelobe level may increase and the mainlobe width (MLW) widen under a mismatched condition, resulting in loss of axial resolution. We propose the use of the fractional Fourier transform (FrFT) as an alternative tool to perform compression of the chirp-coded SHC generated as a result of the nonlinear propagation of an ultrasound signal. Two methods are used to experimentally assess the performance benefits of the FrFT technique over the HMF techniques. The first method uses chirp excitation with central frequency of 2.25 MHz and bandwidth of 1 MHz. The second method uses chirp excitation with pulse inversion to increase the bandwidth to 2 MHz. In this study, experiments were performed in a water tank with a single-element transducer mounted coaxially with a hydrophone in a pitch-catch configuration. Results are presented that indicate that the FrFT can perform pulse compression of the second harmonic chirp component, with a 14% reduction in the MLW of the compressed signal when compared with the HMF. Also, the FrFT provides at least 23% reduction in the MLW of the compressed signal when compared with the harmonic mismatched filter (HMMF). The FrFT maintains comparable peak and integrated sidelobe levels when compared with the HMF and HMMF techniques. Copyright 2010 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

An Ultra-Low Power Turning Angle Based Biomedical Signal Compression Engine with Adaptive Threshold Tuning

PubMed Central

Zhou, Jun; Wang, Chao

2017-01-01

Intelligent sensing is drastically changing our everyday life including healthcare by biomedical signal monitoring, collection, and analytics. However, long-term healthcare monitoring generates tremendous data volume and demands significant wireless transmission power, which imposes a big challenge for wearable healthcare sensors usually powered by batteries. Efficient compression engine design to reduce wireless transmission data rate with ultra-low power consumption is essential for wearable miniaturized healthcare sensor systems. This paper presents an ultra-low power biomedical signal compression engine for healthcare data sensing and analytics in the era of big data and sensor intelligence. It extracts the feature points of the biomedical signal by window-based turning angle detection. The proposed approach has low complexity and thus low power consumption while achieving a large compression ratio (CR) and good quality of reconstructed signal. Near-threshold design technique is adopted to further reduce the power consumption on the circuit level. Besides, the angle threshold for compression can be adaptively tuned according to the error between the original signal and reconstructed signal to address the variation of signal characteristics from person to person or from channel to channel to meet the required signal quality with optimal CR. For demonstration, the proposed biomedical compression engine has been used and evaluated for ECG compression. It achieves an average (CR) of 71.08% and percentage root-mean-square difference (PRD) of 5.87% while consuming only 39 nW. Compared to several state-of-the-art ECG compression engines, the proposed design has significantly lower power consumption while achieving similar CRD and PRD, making it suitable for long-term wearable miniaturized sensor systems to sense and collect healthcare data for remote data analytics. PMID:28783079

An Ultra-Low Power Turning Angle Based Biomedical Signal Compression Engine with Adaptive Threshold Tuning.

PubMed

Zhou, Jun; Wang, Chao

2017-08-06

Intelligent sensing is drastically changing our everyday life including healthcare by biomedical signal monitoring, collection, and analytics. However, long-term healthcare monitoring generates tremendous data volume and demands significant wireless transmission power, which imposes a big challenge for wearable healthcare sensors usually powered by batteries. Efficient compression engine design to reduce wireless transmission data rate with ultra-low power consumption is essential for wearable miniaturized healthcare sensor systems. This paper presents an ultra-low power biomedical signal compression engine for healthcare data sensing and analytics in the era of big data and sensor intelligence. It extracts the feature points of the biomedical signal by window-based turning angle detection. The proposed approach has low complexity and thus low power consumption while achieving a large compression ratio (CR) and good quality of reconstructed signal. Near-threshold design technique is adopted to further reduce the power consumption on the circuit level. Besides, the angle threshold for compression can be adaptively tuned according to the error between the original signal and reconstructed signal to address the variation of signal characteristics from person to person or from channel to channel to meet the required signal quality with optimal CR. For demonstration, the proposed biomedical compression engine has been used and evaluated for ECG compression. It achieves an average (CR) of 71.08% and percentage root-mean-square difference (PRD) of 5.87% while consuming only 39 nW. Compared to several state-of-the-art ECG compression engines, the proposed design has significantly lower power consumption while achieving similar CRD and PRD, making it suitable for long-term wearable miniaturized sensor systems to sense and collect healthcare data for remote data analytics.

Compression of Morbidity and Mortality: New Perspectives1

PubMed Central

Stallard, Eric

2017-01-01

Compression of morbidity is a reduction over time in the total lifetime days of chronic disability, reflecting a balance between (1) morbidity incidence rates and (2) case-continuance rates—generated by case-fatality and case-recovery rates. Chronic disability includes limitations in activities of daily living and cognitive impairment, which can be covered by long-term care insurance. Morbidity improvement can lead to a compression of morbidity if the reductions in age-specific prevalence rates are sufficiently large to overcome the increases in lifetime disability due to concurrent mortality improvements and progressively higher disability prevalence rates with increasing age. Compression of mortality is a reduction over time in the variance of age at death. Such reductions are generally accompanied by increases in the mean age at death; otherwise, for the variances to decrease, the death rates above the mean age at death would need to increase, and this has rarely been the case. Mortality improvement is a reduction over time in the age-specific death rates and a corresponding increase in the cumulative survival probabilities and age-specific residual life expectancies. Mortality improvement does not necessarily imply concurrent compression of mortality. This paper reviews these concepts, describes how they are related, shows how they apply to changes in mortality over the past century and to changes in morbidity over the past 30 years, and discusses their implications for future changes in the United States. The major findings of the empirical analyses are the substantial slowdowns in the degree of mortality compression over the past half century and the unexpectedly large degree of morbidity compression that occurred over the morbidity/disability study period 1984–2004; evidence from other published sources suggests that morbidity compression may be continuing. PMID:28740358

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Technical Reports Server (NTRS)

Barrie, A.; Adrian, Mark L.; Yeh, P.-S.; Winkert, G. E.; Lobell, J. V.; Vinas, A.F.; Simpson, D. J.; Moore, T. E.

2008-01-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eights (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 deg x 180 deg fields-of-view (FOV) are set 90 deg apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 deg x 180 deg fan about its nominal viewing (0 deg deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the results in the DES complement of a given spacecraft generating 6.5-Mbs(exp -1) of electron data while the DIS generates 1.1-Mbs(exp -1) of ion data yielding an FPI total data rate of 6.6-MBs(exp -1). The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mbs(exp -1). Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements. Topics to be discussed include: review of compression algorithm; data quality; data formatting/organization; and, implications for data/matrix pruning. To conclude a presentation of the base-lined FPI data compression approach is provided.

Effects of flashlight guidance on chest compression performance in cardiopulmonary resuscitation in a noisy environment.

PubMed

You, Je Sung; Chung, Sung Phil; Chang, Chul Ho; Park, Incheol; Lee, Hye Sun; Kim, SeungHo; Lee, Hahn Shick

2013-08-01

In real cardiopulmonary resuscitation (CPR), noise can arise from instructional voices and environmental sounds in places such as a battlefield and industrial and high-traffic areas. A feedback device using a flashing light was designed to overcome noise-induced stimulus saturation during CPR. This study was conducted to determine whether 'flashlight' guidance influences CPR performance in a simulated noisy setting. We recruited 30 senior medical students with no previous experience of using flashlight-guided CPR to participate in this prospective, simulation-based, crossover study. The experiment was conducted in a simulated noisy situation using a cardiac arrest model without ventilation. Noise such as patrol car and fire engine sirens was artificially generated. The flashlight guidance device emitted light pulses at the rate of 100 flashes/min. Participants also received instructions to achieve the desired rate of 100 compressions/min. CPR performances were recorded with a Resusci Anne mannequin with a computer skill-reporting system. There were significant differences between the control and flashlight groups in mean compression rate (MCR), MCR/min and visual analogue scale. However, there were no significant differences in correct compression depth, mean compression depth, correct hand position, and correctly released compression. The flashlight group constantly maintained the pace at the desired 100 compressions/min. Furthermore, the flashlight group had a tendency to keep the MCR constant, whereas the control group had a tendency to decrease it after 60 s. Flashlight-guided CPR is particularly advantageous for maintaining a desired MCR during hands-only CPR in noisy environments, where metronome pacing might not be clearly heard.

The impact of skull bone intensity on the quality of compressed CT neuro images

NASA Astrophysics Data System (ADS)

Kowalik-Urbaniak, Ilona; Vrscay, Edward R.; Wang, Zhou; Cavaro-Menard, Christine; Koff, David; Wallace, Bill; Obara, Boguslaw

2012-02-01

The increasing use of technologies such as CT and MRI, along with a continuing improvement in their resolution, has contributed to the explosive growth of digital image data being generated. Medical communities around the world have recognized the need for efficient storage, transmission and display of medical images. For example, the Canadian Association of Radiologists (CAR) has recommended compression ratios for various modalities and anatomical regions to be employed by lossy JPEG and JPEG2000 compression in order to preserve diagnostic quality. Here we investigate the effects of the sharp skull edges present in CT neuro images on JPEG and JPEG2000 lossy compression. We conjecture that this atypical effect is caused by the sharp edges between the skull bone and the background regions as well as between the skull bone and the interior regions. These strong edges create large wavelet coefficients that consume an unnecessarily large number of bits in JPEG2000 compression because of its bitplane coding scheme, and thus result in reduced quality at the interior region, which contains most diagnostic information in the image. To validate the conjecture, we investigate a segmentation based compression algorithm based on simple thresholding and morphological operators. As expected, quality is improved in terms of PSNR as well as the structural similarity (SSIM) image quality measure, and its multiscale (MS-SSIM) and informationweighted (IW-SSIM) versions. This study not only supports our conjecture, but also provides a solution to improve the performance of JPEG and JPEG2000 compression for specific types of CT images.

The application of compressed sensing to long-term acoustic emission-based structural health monitoring

NASA Astrophysics Data System (ADS)

Cattaneo, Alessandro; Park, Gyuhae; Farrar, Charles; Mascareñas, David

2012-04-01

The acoustic emission (AE) phenomena generated by a rapid release in the internal stress of a material represent a promising technique for structural health monitoring (SHM) applications. AE events typically result in a discrete number of short-time, transient signals. The challenge associated with capturing these events using classical techniques is that very high sampling rates must be used over extended periods of time. The result is that a very large amount of data is collected to capture a phenomenon that rarely occurs. Furthermore, the high energy consumption associated with the required high sampling rates makes the implementation of high-endurance, low-power, embedded AE sensor nodes difficult to achieve. The relatively rare occurrence of AE events over long time scales implies that these measurements are inherently sparse in the spike domain. The sparse nature of AE measurements makes them an attractive candidate for the application of compressed sampling techniques. Collecting compressed measurements of sparse AE signals will relax the requirements on the sampling rate and memory demands. The focus of this work is to investigate the suitability of compressed sensing techniques for AE-based SHM. The work explores estimating AE signal statistics in the compressed domain for low-power classification applications. In the event compressed classification finds an event of interest, ι1 norm minimization will be used to reconstruct the measurement for further analysis. The impact of structured noise on compressive measurements is specifically addressed. The suitability of a particular algorithm, called Justice Pursuit, to increase robustness to a small amount of arbitrary measurement corruption is investigated.

Longitudinal compressive behaviour of 3D braided composite under various temperatures and strain rates

NASA Astrophysics Data System (ADS)

Pan, Zhongxiang; Gu, Bohong; Sun, Baozhong

2015-03-01

This paper reports the longitudinal compressive behaviour of 3D braided basalt fibre tows/epoxy composite materials under strain-rate range of 1,200-2,400 s-1 and temperature range of 23-210 °C both in experimental and finite element analyses (FEA). A split Hopkinson pressure bar system with a heating device was designed to test the longitudinal compressive behaviour of 3D braided composite materials. Testing results indicate that longitudinal compression modulus, specific energy absorption and peak stress decreased with elevated temperatures, whereas the failure strain increased with elevated temperatures. At some temperatures above the T g of epoxy resin, such as at 120 and 150 °C, strain distributions and deformations in fibre tows and epoxy resin tended to be the same. It results in relatively slighter damage status of the 3D braided composite material. The FEA results reveal that heating of the material due to the dissipative energy of the inelastic deformation and damage processes generated in resin is more than that in fibre tows. The braiding structure has a significant influence on thermomechanical failure via two aspects: distribution and accumulation of the heating leads to the development of the shear band paths along braiding angle; the buckling inflection segment rather than the straight segment generates the maximum of the heating in each fibre tows. The damage occurs at the early stage when the temperature is below T g, while at the temperature above T g, damage stage occurs at the rear of plastic deformation.

Laser Driven Compression Equations of State and Hugoniot Pressure Measurements in Thick Solid Metallic Targets at ˜0.17-13 TW/cm2

NASA Astrophysics Data System (ADS)

Remo, John L.

2010-10-01

An electro-optic laser probe was developed to obtain parameters for high energy density equations of state (EoS), Hugoniot pressures (PH), and strain rates for high energy density laser irradiation intensity, I, experiments at ˜170 GW/cm2 (λ = 1064 nm) to ˜13 TW/cm2 (λ = 527 nm) on Al, Cu, Ti, Fe, Ni metal targets in a vacuum. At I ˜7 TW/cm2 front surface plasma pressures and temperatures reached 100's GPa and over two million K. Rear surface PH ranged from 7-120 GPa at average shock wave transit velocities 4.2-8.5 km/s, depending on target thickness and I. A surface plasma compression ˜100's GPa generated an impulsive radial expanding shock wave causing compression, rarefactions, and surface elastic and plastic deformations depending on I. A laser/fiber optic system measured rear surface shock wave emergence and particle velocity with ˜3 GHz resolution by monitoring light deflection from diamond polished rear surfaces of malleable metallic targets, analogous to an atomic force microscope. Target thickness, ˜0.5-2.9 mm, prevented front surface laser irradiation penetration, due to low radiation skin depth, from altering rear surface reflectivity (refractive index). At ˜10 TW electromagnetic plasma pulse noise generated from the target chamber overwhelmed detector signals. Pulse frequency analysis using Moebius loop antennae probed transient noise characteristics. Average shock (compression) and particle (rear surface displacement) velocity measurements determined rear surface PH and GPa) EoS that are compared with gas guns.

Flow and compaction properties of hypromellose: new directly compressible versus the established grades.

PubMed

Grdešič, Peter; Vrečer, Franc; Ilić, Ilija

2016-11-01

Information about flow and compaction properties of hypromellose (HPMC) polymers is essential for the technologists who are facing challenges regarding poor flow and compaction while developing new controlled release matrix tablets. There is a profound lack of studies in this field and none of the published ones deal with the compaction of the newly introduced HPMC grades specifically designed for direct compression (DC). The objective behind this study was the evaluation of flow and compaction properties of six different grades of HPMC substitution type 2208 polymers, including two second generation directly compressible grades from Dow Chemical Company (K100LV, K15M, K4M CR, K4M DC, K100M CR and K100M DC). Flow properties were determined using flow time and Carr index. Compaction properties were quantified using "out-of-die" Heckel and modified Walker models as well as tensile strength profile and elastic recovery. We used statistical approach to analyze the results. Due to larger, rounder and smoother particles both DC grades showed distinctly better flow properties compared to their non-DC counterparts. Overall, K15M showed the best compaction properties, closely followed by K100LV. K100M grades showed superior compaction properties over K4M grades. The new, second generation DC grades had poorer compaction properties, however, they exhibited better flow properties on the other hand. Considering all compaction results, the Heckel model gave better description of compressibility compared to the Walker model, so it may be preferred in case of studying HPMC polymers and other similar materials.

Quinary excitation method for pulse compression ultrasound measurements.

PubMed

Cowell, D M J; Freear, S

2008-04-01

A novel switched excitation method for linear frequency modulated excitation of ultrasonic transducers in pulse compression systems is presented that is simple to realise, yet provides reduced signal sidelobes at the output of the matched filter compared to bipolar pseudo-chirp excitation. Pulse compression signal sidelobes are reduced through the use of simple amplitude tapering at the beginning and end of the excitation duration. Amplitude tapering using switched excitation is realised through the use of intermediate voltage switching levels, half that of the main excitation voltages. In total five excitation voltages are used creating a quinary excitation system. The absence of analogue signal generation and power amplifiers renders the excitation method attractive for applications with requirements such as a high channel count or low cost per channel. A systematic study of switched linear frequency modulated excitation methods with simulated and laboratory based experimental verification is presented for 2.25 MHz non-destructive testing immersion transducers. The signal to sidelobe noise level of compressed waveforms generated using quinary and bipolar pseudo-chirp excitation are investigated for transmission through a 0.5m water and kaolin slurry channel. Quinary linear frequency modulated excitation consistently reduces signal sidelobe power compared to bipolar excitation methods. Experimental results for transmission between two 2.25 MHz transducers separated by a 0.5m channel of water and 5% kaolin suspension shows improvements in signal to sidelobe noise power in the order of 7-8 dB. The reported quinary switched method for linear frequency modulated excitation provides improved performance compared to pseudo-chirp excitation without the need for high performance excitation amplifiers.

Non-destructive measurement and role of surface residual stress monitoring in residual life assessment of a steam turbine blading material

NASA Astrophysics Data System (ADS)

Prabhu-Gaunkar, Gajanana; Rawat, M. S.; Prasad, C. R.

2014-02-01

Steam turbine blades in power generation equipment are made from martensitic stainless steels having high strength, good toughness and corrosion resistance. However, these steels are susceptible to pitting which can promote early failures of blades in the turbines, particularly in the low pressure dry/wet areas by stress corrosion and corrosion fatigue. Presence of tensile residual stresses is known to accelerate failures whereas compressive stresses can help in delaying failures. Shot peening has been employed as an effective tool to induce compressive residual stresses which offset a part of local surface tensile stresses in the surface layers of components. Maintaining local stresses at stress raisers, such as pits formed during service, below a threshold level can help in preventing the initiation microcracks and failures. The thickness of the layer in compression will, however, depend of the shot peening parameters and should extend below the bottom of corrosion pits. The magnitude of surface compressive drops progressively during service exposure and over time the effectiveness of shot peening is lost making the material susceptible to micro-crack initiation once again. Measurement and monitoring of surface residual stress therefore becomes important for assessing residual life of components in service. This paper shows the applicability of surface stress monitoring to life assessment of steam turbine blade material based on data generated in laboratory on residual surface stress measurements in relation to fatigue exposure. An empirical model is proposed to calculate the remaining life of shot peened steam turbine blades in service.

Laser-pulse compression using magnetized plasmas

DOE PAGES

Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

2017-02-28

Proposals to reach the next generation of laser intensities through Raman or Brillouin backscattering have centered on optical frequencies. Higher frequencies are beyond the range of such methods mainly due to the wave damping that accompanies the higher-density plasmas necessary for compressing higher frequency lasers. However, we find that an external magnetic field transverse to the direction of laser propagation can reduce the required plasma density. Using parametric interactions in magnetized plasmas to mediate pulse compression, both reduces the wave damping and alleviates instabilities, thereby enabling higher frequency or lower intensity pumps to produce pulses at higher intensities and longermore » durations. Finally, in addition to these theoretical advantages, our method in which strong uniform magnetic fields lessen the need for high-density uniform plasmas also lessens key engineering challenges or at least exchanges them for different challenges.« less

High-speed real-time image compression based on all-optical discrete cosine transformation

NASA Astrophysics Data System (ADS)

Guo, Qiang; Chen, Hongwei; Wang, Yuxi; Chen, Minghua; Yang, Sigang; Xie, Shizhong

2017-02-01

In this paper, we present a high-speed single-pixel imaging (SPI) system based on all-optical discrete cosine transform (DCT) and demonstrate its capability to enable noninvasive imaging of flowing cells in a microfluidic channel. Through spectral shaping based on photonic time stretch (PTS) and wavelength-to-space conversion, structured illumination patterns are generated at a rate (tens of MHz) which is three orders of magnitude higher than the switching rate of a digital micromirror device (DMD) used in a conventional single-pixel camera. Using this pattern projector, high-speed image compression based on DCT can be achieved in the optical domain. In our proposed system, a high compression ratio (approximately 10:1) and a fast image reconstruction procedure are both achieved, which implicates broad applications in industrial quality control and biomedical imaging.

Core/corona modeling of diode-imploded annular loads

NASA Astrophysics Data System (ADS)

Terry, R. E.; Guillory, J. U.

1980-11-01

The effects of a tenuous exterior plasma corona with anomalous resistivity on the compression and heating of a hollow, collisional aluminum z-pinch plasma are predicted by a one-dimensional code. As the interior ("core") plasma is imploded by its axial current, the energy exchange between core and corona determines the current partition. Under the conditions of rapid core heating and compression, the increase in coronal current provides a trade-off between radial acceleration and compression, which reduces the implosion forces and softens the pitch. Combined with a heuristic account of energy and momentum transport in the strongly coupled core plasma and an approximate radiative loss calculation including Al line, recombination and Bremsstrahlung emission, the current model can provide a reasonably accurate description of imploding annular plasma loads that remain azimuthally symmetric. The implications for optimization of generator load coupling are examined.

Estimation of mechanical properties of nanomaterials using artificial intelligence methods

NASA Astrophysics Data System (ADS)

Vijayaraghavan, V.; Garg, A.; Wong, C. H.; Tai, K.

2014-09-01

Computational modeling tools such as molecular dynamics (MD), ab initio, finite element modeling or continuum mechanics models have been extensively applied to study the properties of carbon nanotubes (CNTs) based on given input variables such as temperature, geometry and defects. Artificial intelligence techniques can be used to further complement the application of numerical methods in characterizing the properties of CNTs. In this paper, we have introduced the application of multi-gene genetic programming (MGGP) and support vector regression to formulate the mathematical relationship between the compressive strength of CNTs and input variables such as temperature and diameter. The predictions of compressive strength of CNTs made by these models are compared to those generated using MD simulations. The results indicate that MGGP method can be deployed as a powerful method for predicting the compressive strength of the carbon nanotubes.

Global expression for representing cohesive-energy curves. II

NASA Technical Reports Server (NTRS)

Schlosser, Herbert; Ferrante, John

1993-01-01

Schlosser et al. (1991) showed that the R dependence of the cohesive energy of partially ionic solids may be characterized by a two-term energy relationship consisting of a Coulomb term arising from the charge transfer, delta-Z, and a scaled universal energy function, E*(a *), which accounts for the partially covalent character of the bond and for repulsion between the atomic cores for small R; a* is a scaled length. In the paper by Schlosser et al., the normalized cohesive-energy curves of NaCl-structure alkali-halide crystals were generated with this expression. In this paper we generate the cohesive-energy curves of several families of partially ionic solids with different crystal structures and differing degrees of ionicity. These include the CsCl-structure Cs halides, and the Tl and Ag halides, which have weaker ionic bonding than the alkali halides, and which have the CsCl and NaCl structures, respectively. The cohesive-energy-curve parameters are then used to generate theoretical isothermal compression curves for the Li, Na, K, Cs, and Ag halides. We find good agreement with the available experimental compression data.

Combined Yb/Nd driver for optical parametric chirped pulse amplifiers.

PubMed

Michailovas, Kirilas; Baltuska, Andrius; Pugzlys, Audrius; Smilgevicius, Valerijus; Michailovas, Andrejus; Zaukevicius, Audrius; Danilevicius, Rokas; Frankinas, Saulius; Rusteika, Nerijus

2016-09-19

We report on the developed front-end/pump system for optical parametric chirped pulse amplifiers. The system is based on a dual output fiber oscillator/power amplifier which seeds and assures all-optical synchronization of femtosecond Yb and picosecond Nd laser amplifiers operating at a central wavelength of 1030 nm and 1064 nm, respectively. At the central wavelength of 1030 nm, the fiber oscillator generates partially stretched 4 ps pulses with the spectrum supporting a <120 fs pulse duration and pulse energy of 0.45 nJ. The energy of generated 1064 nm pulses is 0.15 nJ, which is sufficient for the efficient seeding of high-contrast Nd:YVO chirped pulse regenerative amplifier/post amplifier systems generating 9 mJ pulses compressible to 16 ps duration. The power amplification stages, based on Nd:YAG crystals, provide 62 mJ pulses compressible to 20 ps pulse duration at a repetition rate of 1 kHz. Further energy scaling currently is prevented by limited dimensions of the diffraction gratings, which, because of the fast progress in MLD grating manufacturing technologies is only a temporary obstacle.

Euler Technology Assessment for Preliminary Aircraft Design: Compressibility Predictions by Employing the Cartesian Unstructured Grid SPLITFLOW Code

NASA Technical Reports Server (NTRS)

Finley, Dennis B.; Karman, Steve L., Jr.

1996-01-01

The objective of the second phase of the Euler Technology Assessment program was to evaluate the ability of Euler computational fluid dynamics codes to predict compressible flow effects over a generic fighter wind tunnel model. This portion of the study was conducted by Lockheed Martin Tactical Aircraft Systems, using an in-house Cartesian-grid code called SPLITFLOW. The Cartesian grid technique offers several advantages, including ease of volume grid generation and reduced number of cells compared to other grid schemes. SPLITFLOW also includes grid adaption of the volume grid during the solution to resolve high-gradient regions. The SPLITFLOW code predictions of configuration forces and moments are shown to be adequate for preliminary design, including predictions of sideslip effects and the effects of geometry variations at low and high angles-of-attack. The transonic pressure prediction capabilities of SPLITFLOW are shown to be improved over subsonic comparisons. The time required to generate the results from initial surface data is on the order of several hours, including grid generation, which is compatible with the needs of the design environment.

Statistical Compression of Wind Speed Data

NASA Astrophysics Data System (ADS)

Tagle, F.; Castruccio, S.; Crippa, P.; Genton, M.

2017-12-01

In this work we introduce a lossy compression approach that utilizes a stochastic wind generator based on a non-Gaussian distribution to reproduce the internal climate variability of daily wind speed as represented by the CESM Large Ensemble over Saudi Arabia. Stochastic wind generators, and stochastic weather generators more generally, are statistical models that aim to match certain statistical properties of the data on which they are trained. They have been used extensively in applications ranging from agricultural models to climate impact studies. In this novel context, the parameters of the fitted model can be interpreted as encoding the information contained in the original uncompressed data. The statistical model is fit to only 3 of the 30 ensemble members and it adequately captures the variability of the ensemble in terms of seasonal internannual variability of daily wind speed. To deal with such a large spatial domain, it is partitioned into 9 region, and the model is fit independently to each of these. We further discuss a recent refinement of the model, which relaxes this assumption of regional independence, by introducing a large-scale component that interacts with the fine-scale regional effects.

Ocean wave electric generators

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

Rosenberg, H.R.

This patent describes an apparatus for generating electricity from ocean waves. It consists of: 1.) a hollow buoyant duck positioned in the path of waves including a core about the center axis of which the duck rotates, a lower chamber portion having liquid therein and an upper chamber portion having air therein. The air is alternately compressed and expanded by the liquid in the chamber during the rotational motion of the duck caused by waves. A turbine mounted in the upper portion of the duck is driven by the compressed and expanded air. A generator is coupled to the turbinemore » and operated to produce electrical energy and an air bulb; 2.) a spine having a transverse axial shaft anchoring the spine to the ocean floor. The upper portion of the spine engages the duck to maintain the duck in position. The spine has a curved configuration to concentrate and direct wave energy. The spine configuration acts as a scoop to increase the height of wave peaks and as a foil to increase the depth of wave troughs.« less

Estimation of Psychophysical Thresholds Based on Neural Network Analysis of DPOAE Input/Output Functions

NASA Astrophysics Data System (ADS)

Naghibolhosseini, Maryam; Long, Glenis

2011-11-01

The distortion product otoacoustic emission (DPOAE) input/output (I/O) function may provide a potential tool for evaluating cochlear compression. Hearing loss causes an increase in the level of the sound that is just audible for the person, which affects the cochlea compression and thus the dynamic range of hearing. Although the slope of the I/O function is highly variable when the total DPOAE is used, separating the nonlinear-generator component from the reflection component reduces this variability. We separated the two components using least squares fit (LSF) analysis of logarithmic sweeping tones, and confirmed that the separated generator component provides more consistent I/O functions than the total DPOAE. In this paper we estimated the slope of the I/O functions of the generator components at different sound levels using LSF analysis. An artificial neural network (ANN) was used to estimate psychophysical thresholds using the estimated slopes of the I/O functions. DPOAE I/O functions determined in this way may help to estimate hearing thresholds and cochlear health.

Investigating Friction as a Main Source of Entropy Generation in the Expansion of Confined Gas in a Piston-and-Cylinder Device

ERIC Educational Resources Information Center

Kang, Dun-Yen; Liou, Kai-Hsin; Chang, Wei-Lun

2015-01-01

The expansion or compression of gas confined in a piston-and-cylinder device is a classic working example used for illustrating the First and Second Laws of Thermodynamics. The balance of energy and entropy enables the estimation of a number of thermodynamic properties. The entropy generation (also called entropy production) resulting from this…

DNA sequence similarity recognition by hybridization to short oligomers

DOEpatents

Milosavljevic, Aleksandar

1999-01-01

Methods are disclosed for the comparison of nucleic acid sequences. Data is generated by hybridizing sets of oligomers with target nucleic acids. The data thus generated is manipulated simultaneously with respect to both (i) matching between oligomers and (ii) matching between oligomers and putative reference sequences available in databases. Using data compression methods to manipulate this mutual information, sequences for the target can be constructed.

Finite-element modeling of compression and gravity on a population of breast phantoms for multimodality imaging simulation.

PubMed

Sturgeon, Gregory M; Kiarashi, Nooshin; Lo, Joseph Y; Samei, E; Segars, W P

2016-05-01

The authors are developing a series of computational breast phantoms based on breast CT data for imaging research. In this work, the authors develop a program that will allow a user to alter the phantoms to simulate the effect of gravity and compression of the breast (craniocaudal or mediolateral oblique) making the phantoms applicable to multimodality imaging. This application utilizes a template finite-element (FE) breast model that can be applied to their presegmented voxelized breast phantoms. The FE model is automatically fit to the geometry of a given breast phantom, and the material properties of each element are set based on the segmented voxels contained within the element. The loading and boundary conditions, which include gravity, are then assigned based on a user-defined position and compression. The effect of applying these loads to the breast is computed using a multistage contact analysis in FEBio, a freely available and well-validated FE software package specifically designed for biomedical applications. The resulting deformation of the breast is then applied to a boundary mesh representation of the phantom that can be used for simulating medical images. An efficient script performs the above actions seamlessly. The user only needs to specify which voxelized breast phantom to use, the compressed thickness, and orientation of the breast. The authors utilized their FE application to simulate compressed states of the breast indicative of mammography and tomosynthesis. Gravity and compression were simulated on example phantoms and used to generate mammograms in the craniocaudal or mediolateral oblique views. The simulated mammograms show a high degree of realism illustrating the utility of the FE method in simulating imaging data of repositioned and compressed breasts. The breast phantoms and the compression software can become a useful resource to the breast imaging research community. These phantoms can then be used to evaluate and compare imaging modalities that involve different positioning and compression of the breast.

First in-situ monitoring of CO2 delivery to the mantle followed by compression melting, using synchrotron generated X-ray diffraction.

NASA Astrophysics Data System (ADS)

Hammouda, Tahar; Chantel, Julien; Manthilake, Geeth; Guignard, Jérémy; Crichton, Wilson; Gaillard, Fabrice

2014-05-01

Melting of peridotite + CO2 upon compression has been directly monitored in situ, for the first time. We have combined high pressure experiments in the multianvil apparatus with synchrotron-generated X-ray diffraction, in order to monitor sample decarbonation upon heating, followed by melting upon compression. Experiments were performed in the model system CaO-MgO-SiO2+CO2, using dolomite and silicates contained in graphite capsules as starting material. Save Al, starting composition was aimed at reproducing peridotitic system. The sample was first compressed at room temperature, then heated. Decarbonation was observed at 2.2 GPa and 1100°C. After further heating to 1300°C, pressure was increased. Melting was observed at 2.7 GPa, while temperature was kept at 1300°C. All transformations were followed using X-ray diffraction. Starting with silicate + carbonate mixtures, we were thus able to keep CO2 fluid in the experimental sample at high P and T, up to the solidus. Concerning carbon recycling at subduction zones, it is known that CO2 is a non-wetting fluid in silicate aggregates. Therefore, any CO2 resulting from carbonate breakdown likely remains trapped at grain corners either in the subducted lithosphere or in the mantle wedge before eventually being trapped in mantle minerals as fluid inclusions, due to dynamic recrystallization. In this way, CO2 released from the slab may be spread laterally due to mantle convection. Entrainment to further depths by deep subduction or in convection cells induces CO2 introduction to depth wherein the solidus can be crossed, due to pressure increase. The solidus corresponds to the so-called carbonate ledge, beyond which carbonatitic melts are produced. Therefore, compression melting of CO2-bearing lithologies is a way to produce carbonatitic melts at depths corresponding to about 80 km. This mechanism is a viable explanation for the observed geophysical anomalies, such as those revealed by electrical conductivity measurements.

Unambiguous demonstration of soliton evolution in slow-light silicon photonic crystal waveguides with SFG-XFROG.

PubMed

Li, Xiujian; Liao, Jiali; Nie, Yongming; Marko, Matthew; Jia, Hui; Liu, Ju; Wang, Xiaochun; Wong, Chee Wei

2015-04-20

We demonstrate the temporal and spectral evolution of picosecond soliton in the slow light silicon photonic crystal waveguides (PhCWs) by sum frequency generation cross-correlation frequency resolved optical grating (SFG-XFROG) and nonlinear Schrödinger equation (NLSE) modeling. The reference pulses for the SFG-XFROG measurements are unambiguously pre-characterized by the second harmonic generation frequency resolved optical gating (SHG-FROG) assisted with the combination of NLSE simulations and optical spectrum analyzer (OSA) measurements. Regardless of the inevitable nonlinear two photon absorption, high order soliton compressions have been observed remarkably owing to the slow light enhanced nonlinear effects in the silicon PhCWs. Both the measurements and the further numerical analyses of the pulse dynamics indicate that, the free carrier dispersion (FCD) enhanced by the slow light effects is mainly responsible for the compression, the acceleration, and the spectral blue shift of the soliton.

Exhaust Nozzle Plume and Shock Wave Interaction

NASA Technical Reports Server (NTRS)

Castner, Raymond S.; Elmiligui, Alaa; Cliff, Susan

2013-01-01

Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the exhaust plume. Both the nozzle exhaust plume shape and the tail shock shape may be affected by an interaction that may alter the vehicle sonic boom signature. The plume and shock interaction was studied using Computational Fluid Dynamics simulation on two types of convergent-divergent nozzles and a simple wedge shock generator. The nozzle plume effects on the lower wedge compression region are evaluated for two- and three-dimensional nozzle plumes. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the deflected lower plume boundary. The sonic boom pressure signature of the wedge is modified by the presence of the plume, and the computational predictions show significant (8 to 15 percent) changes in shock amplitude.

Biomechanical testing of bioabsorbable cannulated screws for slipped capital femoral epiphysis fixation.

PubMed

Kroeber, Markus W; Rovinsky, David; Haskell, Andrew; Heilmann, Moira; Llotz, Jeff; Otsuka, Norman

2002-06-01

This study compared cannulated 4.5-mm bioabsorbable screws made of self-reinforced poly-levolactic acid to cannulated 4.5-mm steel and titanium screws for resistance to shear stress and ability to generate compression in a polyurethane foam model of slipped capital femoral epiphysis fixation. The maximum shear stress resisted by the three screw types was similar (self-reinforced poly-levolactic acid 371 +/- 146 MPa, steel 442 +/- 43 MPa, and titanium 470 +/- 91 MPa). The maximum compression generated by both the self-reinforced poly-levolactic acid screw (68.5 +/- 3.3 N) and the steel screw (63.3 +/- 5.9 N) was greater than that for the titanium screw (3 +/- 1.4 N, P <.05). These data suggest cannulated self-reinforced poly-levolactic acid screws can be used in the treatment of slipped capital femoral epiphysis because of their sufficient biomechanical strength.

An electromagnetic railgun accelerator: a generator of strong shock waves in channels

NASA Astrophysics Data System (ADS)

Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.

2014-11-01

Processes that accompany the generation of strong shock waves during the acceleration of a free plasma piston (PP) in the electromagnetic railgun channel have been experimentally studied. The formation of shock waves in the railgun channel and the motion of a shock-wave-compressed layer proceed (in contrast to the case of a classical shock tube) in a rather strong electric field (up to 300 V/cm). The experiments were performed at the initial gas pressures in the channel ranging from 25 to 500 Torr. At 25 Torr, the shock-wave Mach numbers reached 32 in argon and 16 in helium. At high concentrations of charged particles behind the shock wave, the electric field causes the passage of a part of the discharge current through the volume of the shock-wave-compressed layer, which induces intense glow comparable with that of the PP glow.

A Cartesian grid approach with hierarchical refinement for compressible flows

NASA Technical Reports Server (NTRS)

Quirk, James J.

1994-01-01

Many numerical studies of flows that involve complex geometries are limited by the difficulties in generating suitable grids. We present a Cartesian boundary scheme for two-dimensional, compressible flows that is unfettered by the need to generate a computational grid and so it may be used, routinely, even for the most awkward of geometries. In essence, an arbitrary-shaped body is allowed to blank out some region of a background Cartesian mesh and the resultant cut-cells are singled out for special treatment. This is done within a finite-volume framework and so, in principle, any explicit flux-based integration scheme can take advantage of this method for enforcing solid boundary conditions. For best effect, the present Cartesian boundary scheme has been combined with a sophisticated, local mesh refinement scheme, and a number of examples are shown in order to demonstrate the efficacy of the combined algorithm for simulations of shock interaction phenomena.

Numerical analysis of bubble-cluster formation in an ultrasonic field

NASA Astrophysics Data System (ADS)

Kim, Donghyun; Son, Gihun

2016-11-01

Bubble-cluster formation in an ultrasonic field is investigated numerically solving the conservation equations of mass, momentum and energy. The liquid-gas interface is calculated using the volume-of-fluid method with variable gas density to consider the bubble compressibility. The effect of liquid-gas phase change is also included as the interface source terms of the mass and energy equations. The numerical approach is tested through the simulation of the expansion and contraction motion of a compressed bubble adjacent to a wall. When the bubble is placed in an ultrasonic field, it oscillates radially and then collapses violently. Numerical simulation is also performed for bubble-cluster formation induced by an ultrasonic generator, where the generated bubbles are merged into a macrostructure along the acoustic flow field. The effects of ultrasonic power and frequency, liquid properties and pool temperature on the bubble-cluster formation are investigated. This work was supported by the Korea Institute of Energy Research.

Recent advances in lossy compression of scientific floating-point data

NASA Astrophysics Data System (ADS)

Lindstrom, P.

2017-12-01

With a continuing exponential trend in supercomputer performance, ever larger data sets are being generated through numerical simulation. Bandwidth and storage capacity are, however, not keeping pace with this increase in data size, causing significant data movement bottlenecks in simulation codes and substantial monetary costs associated with archiving vast volumes of data. Worse yet, ever smaller fractions of data generated can be stored for further analysis, where scientists frequently rely on decimating or averaging large data sets in time and/or space. One way to mitigate these problems is to employ data compression to reduce data volumes. However, lossless compression of floating-point data can achieve only very modest size reductions on the order of 10-50%. We present ZFP and FPZIP, two state-of-the-art lossy compressors for structured floating-point data that routinely achieve one to two orders of magnitude reduction with little to no impact on the accuracy of visualization and quantitative data analysis. We provide examples of the use of such lossy compressors in climate and seismic modeling applications to effectively accelerate I/O and reduce storage requirements. We further discuss how the design decisions behind these and other compressors impact error distributions and other statistical and differential properties, including derived quantities of interest relevant to each science application.

Mechanic stress generated by a time-varying electromagnetic field on bone surface.

PubMed

Ye, Hui

2018-03-19

Bone cells sense mechanical load, which is essential for bone growth and remodeling. In a fracture, this mechanism is compromised. Electromagnetic stimulation has been widely used to assist in bone healing, but the underlying mechanisms are largely unknown. A recent hypothesis suggests that electromagnetic stimulation could influence tissue biomechanics; however, a detailed quantitative understanding of EM-induced biomechanical changes in the bone is unavailable. This paper used a muscle/bone model to study the biomechanics of the bone under EM exposure. Due to the dielectric properties of the muscle/bone interface, a time-varying magnetic field can generate both compressing and shear stresses on the bone surface, where many mechanical sensing cells are available for cellular mechanotransduction. I calculated these stresses and found that the shear stress is significantly greater than the compressing stress. Detailed parametric analysis suggests that both the compressing and shear stresses are dependent on the geometrical and electrical properties of the muscle and the bone. These stresses are also functions of the orientation of the coil and the frequency of the magnetic field. It is speculated that the EM field could apply biomechanical influence to fractured bone, through the fine-tuning of the controllable field parameters. Graphical abstract Mechanic stress on bone surface in a time-varying magnetic field.

Improving the scalability of hyperspectral imaging applications on heterogeneous platforms using adaptive run-time data compression

NASA Astrophysics Data System (ADS)

Plaza, Antonio; Plaza, Javier; Paz, Abel

2010-10-01

Latest generation remote sensing instruments (called hyperspectral imagers) are now able to generate hundreds of images, corresponding to different wavelength channels, for the same area on the surface of the Earth. In previous work, we have reported that the scalability of parallel processing algorithms dealing with these high-dimensional data volumes is affected by the amount of data to be exchanged through the communication network of the system. However, large messages are common in hyperspectral imaging applications since processing algorithms are pixel-based, and each pixel vector to be exchanged through the communication network is made up of hundreds of spectral values. Thus, decreasing the amount of data to be exchanged could improve the scalability and parallel performance. In this paper, we propose a new framework based on intelligent utilization of wavelet-based data compression techniques for improving the scalability of a standard hyperspectral image processing chain on heterogeneous networks of workstations. This type of parallel platform is quickly becoming a standard in hyperspectral image processing due to the distributed nature of collected hyperspectral data as well as its flexibility and low cost. Our experimental results indicate that adaptive lossy compression can lead to improvements in the scalability of the hyperspectral processing chain without sacrificing analysis accuracy, even at sub-pixel precision levels.

Fracto-mechanoluminescent light emission of EuD4TEA-PDMS composites subjected to high strain-rate compressive loading

NASA Astrophysics Data System (ADS)

Ryu, Donghyeon; Castaño, Nicolas; Bhakta, Raj; Kimberley, Jamie

2017-08-01

The objective of this study is to understand light emission characteristics of fracto-mechanoluminescent (FML) europium tetrakis(dibenzoylmethide)-triethylammonium (EuD4TEA) crystals under high strain-rate compressive loading. As a sensing material that can play a pivotal role for the self-powered impact sensor technology, it is important to understand transformative light emission characteristics of the FML EuD4TEA crystals under high strain-rate compressive loading. First, EuD4TEA crystals were synthesized and embedded into polydimethylsiloxane (PDMS) elastomer to fabricate EuD4TEA-PDMS composite test specimens. Second, the prepared EuD4TEA-PDMS composites were tested using the modified Kolsky bar setup equipped with a high-speed camera. Third, FML light emission was captured to yield 12 bit grayscale video footage, which was processed to quantify the FML light emission. Finally, quantitative parameters were generated by taking into account pixel values and population of pixels of the 12 bit grayscale images to represent FML light intensity. The FML light intensity was correlated with high strain-rate compressive strain and strain rate to understand the FML light emission characteristics under high strain-rate compressive loading that can result from impact occurrences.

The Role of Fluid Compression in Particle Energization during Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Li, X.; Guo, F.; Li, H.; Li, S.

2017-12-01

Theories of particle transport and acceleration have shown that fluid compression is the leading mechanism for particle energization. However, the role of compression in particle energization during magnetic reconnection is unclear. We present a cluster of studies to clarify and show the effect of fluid compression in accelerating particles to high energies during magnetic reconnection. Using fully kinetic reconnection simulations, we show that fluid compression is the leading mechanism for high-energy particle energization. We find that the compressional energization is more important in a low-beta plasma or in a reconnection layer with a weak guide field (the magnetic field component perpendicular to the reconnecting magnetic field), which are relevant to solar flares. Our analysis on 3D kinetic simulations shows that the self-generated turbulence scatters particles and enhances the particle diffusion processes in the acceleration regions. Based on these results, we then study large-scale reconnection acceleration by solving the particle transport equation in a large-scale reconnection layer evolved with MHD simulations. Due to the compressional effect, particles are accelerated to high energies and develop power-law energy distributions. This study clarifies the nature of particle acceleration in reconnection layer and is important to understand particle energization during large-scale acceleration such as solar flares.

Episodic Jurassic to Lower Cretaceous intraplate compression in Central Patagonia during Gondwana breakup

NASA Astrophysics Data System (ADS)

Navarrete, César; Gianni, Guido; Echaurren, Andrés; Kingler, Federico Lince; Folguera, Andrés

2016-12-01

From Lower Jurassic to Lower Cretaceous, several intraplate compression events affected discrete sectors of Central Patagonia, under a general context of crustal extension associated with Gondwana breakup. This was demonstrated by means of 2D and 3D seismic and borehole data, which show partial inversion of Lower and Middle Jurassic extensional structures of the Chubut and Cañadón Asfalto basins, during the earliest stages of breakup. A comparison with surrounding areas in Patagonia, where similar Jurassic intraplate compression was described, allowed the discrimination of three discrete pulses of subtle compression (C1: ∼188-185 Ma; C2: ∼170-163; C3: ∼157-136? Ma). Interestingly, episodic intraplate compressional events are closely followed by high flux magmatic events linked to the westward expansion of the Karoo-Ferrar thermal anomaly, which impacted on the lithosphere of southwest Gondwana in Lower Jurassic. In addition, we determined the approximate direction of the main compressive strain (σ1) compatible with other Jurassic intraplate belts of South America. These observations led us to propose a linkage between a thermo mechanically weakened continental crust due to LIPs activity, changes in plate motions and ridge-push forces generated by the opening of the Weddell Sea, in order to explain intraplate shortening, interrupted while Karoo LIPs magmatic invigoration took place.

Seeding magnetic fields for laser-driven flux compression in high-energy-density plasmas.

PubMed

Gotchev, O V; Knauer, J P; Chang, P Y; Jang, N W; Shoup, M J; Meyerhofer, D D; Betti, R

2009-04-01

A compact, self-contained magnetic-seed-field generator (5 to 16 T) is the enabling technology for a novel laser-driven flux-compression scheme in laser-driven targets. A magnetized target is directly irradiated by a kilojoule or megajoule laser to compress the preseeded magnetic field to thousands of teslas. A fast (300 ns), 80 kA current pulse delivered by a portable pulsed-power system is discharged into a low-mass coil that surrounds the laser target. A >15 T target field has been demonstrated using a <100 J capacitor bank, a laser-triggered switch, and a low-impedance (<1 Omega) strip line. The device has been integrated into a series of magnetic-flux-compression experiments on the 60 beam, 30 kJ OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The initial application is a novel magneto-inertial fusion approach [O. V. Gotchev et al., J. Fusion Energy 27, 25 (2008)] to inertial confinement fusion (ICF), where the amplified magnetic field can inhibit thermal conduction losses from the hot spot of a compressed target. This can lead to the ignition of massive shells imploded with low velocity-a way of reaching higher gains than is possible with conventional ICF.

Main drive optimization of a high-foot pulse shape in inertial confinement fusion implosions

NASA Astrophysics Data System (ADS)

Wang, L. F.; Ye, W. H.; Wu, J. F.; Liu, Jie; Zhang, W. Y.; He, X. T.

2016-12-01

While progress towards hot-spot ignition has been made achieving an alpha-heating dominated state in high-foot implosion experiments [Hurricane et al., Nat. Phys. 12, 800 (2016)] on the National Ignition Facility, improvements are needed to increase the fuel compression for the enhancement of the neutron yield. A strategy is proposed to improve the fuel compression through the recompression of a shock/compression wave generated by the end of the main drive portion of a high-foot pulse shape. Two methods for the peak pulse recompression, namely, the decompression-and-recompression (DR) and simple recompression schemes, are investigated and compared. Radiation hydrodynamic simulations confirm that the peak pulse recompression can clearly improve fuel compression without significantly compromising the implosion stability. In particular, when the convergent DR shock is tuned to encounter the divergent shock from the capsule center at a suitable position, not only the neutron yield but also the stability of stagnating hot-spot can be noticeably improved, compared to the conventional high-foot implosions [Hurricane et al., Phys. Plasmas 21, 056314 (2014)].

A FASTQ compressor based on integer-mapped k-mer indexing for biologist.

PubMed

Zhang, Yeting; Patel, Khyati; Endrawis, Tony; Bowers, Autumn; Sun, Yazhou

2016-03-15

Next generation sequencing (NGS) technologies have gained considerable popularity among biologists. For example, RNA-seq, which provides both genomic and functional information, has been widely used by recent functional and evolutionary studies, especially in non-model organisms. However, storing and transmitting these large data sets (primarily in FASTQ format) have become genuine challenges, especially for biologists with little informatics experience. Data compression is thus a necessity. KIC, a FASTQ compressor based on a new integer-mapped k-mer indexing method, was developed (available at http://www.ysunlab.org/kic.jsp). It offers high compression ratio on sequence data, outstanding user-friendliness with graphic user interfaces, and proven reliability. Evaluated on multiple large RNA-seq data sets from both human and plants, it was found that the compression ratio of KIC had exceeded all major generic compressors, and was comparable to those of the latest dedicated compressors. KIC enables researchers with minimal informatics training to take advantage of the latest sequence compression technologies, easily manage large FASTQ data sets, and reduce storage and transmission cost. Copyright © 2015 Elsevier B.V. All rights reserved.

Wavelet-based compression of M-FISH images.

PubMed

Hua, Jianping; Xiong, Zixiang; Wu, Qiang; Castleman, Kenneth R

2005-05-01

Multiplex fluorescence in situ hybridization (M-FISH) is a recently developed technology that enables multi-color chromosome karyotyping for molecular cytogenetic analysis. Each M-FISH image set consists of a number of aligned images of the same chromosome specimen captured at different optical wavelength. This paper presents embedded M-FISH image coding (EMIC), where the foreground objects/chromosomes and the background objects/images are coded separately. We first apply critically sampled integer wavelet transforms to both the foreground and the background. We then use object-based bit-plane coding to compress each object and generate separate embedded bitstreams that allow continuous lossy-to-lossless compression of the foreground and the background. For efficient arithmetic coding of bit planes, we propose a method of designing an optimal context model that specifically exploits the statistical characteristics of M-FISH images in the wavelet domain. Our experiments show that EMIC achieves nearly twice as much compression as Lempel-Ziv-Welch coding. EMIC also performs much better than JPEG-LS and JPEG-2000 for lossless coding. The lossy performance of EMIC is significantly better than that of coding each M-FISH image with JPEG-2000.

A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray

PubMed Central

Schiffer, A.; Gardner, M. N.; Lynn, R. H.

2017-01-01

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples. PMID:28405383

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

Pace, Edward J.; Binns, Jack; Peña Alvarez, Miriam

The observation of high-temperature superconductivity in hydride sulfide (H2S) at high pressures has generated considerable interest in compressed hydrogen-rich compounds. High-pressure hydrogen selenide (H2Se) has also been predicted to be superconducting at high temperatures; however, its behaviour and stability upon compression remains unknown. In this study, we synthesize H2Se in situ from elemental Se and molecular H2 at pressures of 0.4 GPa and temperatures of 473 K. On compression at 300 K, we observe the high-pressure solid phase sequence (I-I'-IV) of H2Se through Raman spectroscopy and x-ray diffraction measurements, before dissociation into its constituent elements. Through the compression of H2Semore » in H2 media, we also observe the formation of a host-guest structure, (H2Se)2H2, which is stable at the same conditions as H2Se, with respect to decomposition. These measurements show that the behaviour of H2Se is remarkably similar to that of H2S and provides further understanding of the hydrogen chalcogenides under pressure.« less

Short intense ion pulses for materials and warm dense matter research

DOE PAGES

Seidl, Peter A.; Persaud, Arun; Waldron, William L.; ...

2015-08-14

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10 10 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li + ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientificmore » topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Finally, we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.« less

Lossy compression for Animated Web Visualisation

NASA Astrophysics Data System (ADS)

Prudden, R.; Tomlinson, J.; Robinson, N.; Arribas, A.

2017-12-01

This talk will discuss an technique for lossy data compression specialised for web animation. We set ourselves the challenge of visualising a full forecast weather field as an animated 3D web page visualisation. This data is richly spatiotemporal, however it is routinely communicated to the public as a 2D map, and scientists are largely limited to visualising data via static 2D maps or 1D scatter plots. We wanted to present Met Office weather forecasts in a way that represents all the generated data. Our approach was to repurpose the technology used to stream high definition videos. This enabled us to achieve high rates of compression, while being compatible with both web browsers and GPU processing. Since lossy compression necessarily involves discarding information, evaluating the results is an important and difficult problem. This is essentially a problem of forecast verification. The difficulty lies in deciding what it means for two weather fields to be "similar", as simple definitions such as mean squared error often lead to undesirable results. In the second part of the talk, I will briefly discuss some ideas for alternative measures of similarity.

Deformation behaviors of peat with influence of organic matter.

PubMed

Yang, Min; Liu, Kan

2016-01-01

Peat is a kind of special material rich in organic matter. Because of the high content of organic matter, it shows different deformation behaviors from conventional geotechnical materials. Peat grain has a non-negligible compressibility due to the presence of organic matter. Biogas can generate from peat and can be trapped in form of gas bubbles. Considering the natural properties of peat, a special three-phase composition of peat is described which indicates the existence of organic matter and gas bubbles in peat. A stress-strain-time model is proposed for the compression of organic matter, and the surface tension effect is considered in the compression model of gas bubbles. Finally, a mathematical model has been developed to simulate the deformation behavior of peat considering the compressibility of organic matter and entrapped gas bubbles. The deformation process is the coupling of volume variation of organic matter, gas bubbles and water drainage. The proposed model is used to simulate a series of peat laboratory oedometer tests, and the model can well capture the test results with reasonable model parameters. Effects of model parameters on deformation of peat are also analyzed.

Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

DOE PAGES

Ali, S. J.; Bolme, C. A.; Collins, G. W.; ...

2015-04-16

Here, a normal-incidence visible and near-infrared shock wave optical reflectivity diagnostic was constructed to investigate changes in the optical properties of materials under dynamic laser compression. Documenting wavelength- and time-dependent changes in the optical properties of laser-shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved, but we succeeded in doing so by broadening a series of time delayed 800-nm pulses from an ultrafast Ti:sapphire laser to generate high-intensity broadband light at nanosecond time scales. This diagnostic was demonstrated over the wavelength range 450–1150 nm with up to 16 time displaced spectramore » during a single shock experiment. Simultaneous off-normal incidence velocity interferometry (velocity interferometer system for any reflector) characterized the sample under laser-compression and also provided an independent reflectivity measurement at 532 nm wavelength. The shock-driven semiconductor-to-metallic transition in germanium was documented by the way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm.« less

A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray.

PubMed

Schiffer, A; Gardner, M N; Lynn, R H; Tagarielli, V L

2017-03-01

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli ( E. coli ) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

Optimization of poorly compactable drug tablets manufactured by direct compression using the mixture experimental design.

PubMed

Martinello, Tiago; Kaneko, Telma Mary; Velasco, Maria Valéria Robles; Taqueda, Maria Elena Santos; Consiglieri, Vladi O

2006-09-28

The poor flowability and bad compressibility characteristics of paracetamol are well known. As a result, the production of paracetamol tablets is almost exclusively by wet granulation, a disadvantageous method when compared to direct compression. The development of a new tablet formulation is still based on a large number of experiments and often relies merely on the experience of the analyst. The purpose of this study was to apply experimental design methodology (DOE) to the development and optimization of tablet formulations containing high amounts of paracetamol (more than 70%) and manufactured by direct compression. Nineteen formulations, screened by DOE methodology, were produced with different proportions of Microcel 102, Kollydon VA 64, Flowlac, Kollydon CL 30, PEG 4000, Aerosil, and magnesium stearate. Tablet properties, except friability, were in accordance with the USP 28th ed. requirements. These results were used to generate plots for optimization, mainly for friability. The physical-chemical data found from the optimized formulation were very close to those from the regression analysis, demonstrating that the mixture project is a great tool for the research and development of new formulations.

Microstructure Evolution and Flow Stress Model of a 20Mn5 Hollow Steel Ingot during Hot Compression.

PubMed

Liu, Min; Ma, Qing-Xian; Luo, Jian-Bin

2018-03-21

20Mn5 steel is widely used in the manufacture of heavy hydro-generator shaft due to its good performance of strength, toughness and wear resistance. However, the hot deformation and recrystallization behaviors of 20Mn5 steel compressed under high temperature were not studied. In this study, the hot compression experiments under temperatures of 850-1200 °C and strain rates of 0.01/s-1/s are conducted using Gleeble thermal and mechanical simulation machine. And the flow stress curves and microstructure after hot compression are obtained. Effects of temperature and strain rate on microstructure are analyzed. Based on the classical stress-dislocation relation and the kinetics of dynamic recrystallization, a two-stage constitutive model is developed to predict the flow stress of 20Mn5 steel. Comparisons between experimental flow stress and predicted flow stress show that the predicted flow stress values are in good agreement with the experimental flow stress values, which indicates that the proposed constitutive model is reliable and can be used for numerical simulation of hot forging of 20Mn5 hollow steel ingot.

Development of fire resistant, nontoxic aircraft interior materials

NASA Technical Reports Server (NTRS)

Haley, G.; Silverman, B.; Tajima, Y.

1976-01-01

All available newly developed nonmetallic polymers were examined for possible usage in developing fire resistant, nontoxic nonmetallic parts or assemblies for aircraft interiors. Specifically, feasibility for the development of clear films for new decorative laminates, compression moldings, injection molded parts, thermoformed plastic parts, and flexible foams were given primary considerations. Preliminary data on the flame resistant characteristics of the materials were obtained. Preliminary toxicity data were generated from samples of materials submitted from the contractor. Preliminary data on the physical characteristics of various thermoplastic materials to be considered for either compression molded, injection molded, or thermoformed parts were obtained.

In situ stress evolution during magnetron sputtering of transition metal nitride thin films

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

Abadias, G.; Guerin, Ph.

2008-09-15

Stress evolution during reactive magnetron sputtering of TiN, ZrN, and TiZrN layers was studied using real-time wafer curvature measurements. The presence of stress gradients is revealed, as the result of two kinetically competing stress generation mechanisms: atomic peening effect, inducing compressive stress, and void formation, leading to a tensile stress regime predominant at higher film thickness. No stress relaxation is detected during growth interrupt in both regimes. A change from compressive to tensile stress is evidenced with increasing film thickness, Ti content, sputtering pressure, and decreasing bias voltage.

Response of a small-turboshaft-engine compression system to inlet temperature distortion

NASA Technical Reports Server (NTRS)

Biesiadny, T. J.; Klann, G. A.; Little, J. K.

1984-01-01

An experimental investigation was conducted into the response of a small-turboshaft-engine compression system to steady-state and transient inlet temperature distortions. Transient temperature ramps range from less than 100 K/sec to above 610 K/sec and generated instantaneous temperatures to 420 K above ambient. Steady-state temperature distortion levels were limited by the engine hardware temperature list. Simple analysis of the steady-state distortion data indicated that a particle separator at the engine inlet permitted higher levels of temperature distortion before onset of compressor surge than would be expected without the separator.

Letter: Transient interaction between plasma jet and supersonic compression ramp flow

NASA Astrophysics Data System (ADS)

Huang, He-Xia; Tan, Hui-Jun; Sun, Shu; Zhang, Yu-Chao; Cheng, Lin

2018-04-01

The rapid flow evolution between a plasma jet and a 20° compression ramp flow is captured by a high-speed schlieren system at Mach 2.0. Several interesting flow phenomena are observed for the first time. The pulsed jet, which generates strong perturbations, forces the crossflow boundary layer to separate and forms a forward moving shock. A typical shock-on-shock interaction occurs when the precursor shock intersects with the original shock. The interaction is initially regular, and then it transforms into an irregular one with a Mach stem connecting the precursor shock and original ramp shock.

Effects of laser source parameters on the generation of narrow band and directed laser ultrasound

NASA Technical Reports Server (NTRS)

Spicer, James B.; Deaton, John B., Jr.; Wagner, James W.

1992-01-01

Predictive and prescriptive modeling of laser arrays is performed to demonstrate the effects of the extension of array elements on laser array performance. For a repetitively pulsed laser source (the temporal laser array), efficient frequency compression is best achieved by detecting longitudinal waves off-epicenter in plates where the source size and shape directly influence the longitudinal wave shape and duration; the longitudinal array may be tailored for a given repetition frequency to yield efficient overtone energy compression into the fundamental frequency band. For phased arrays, apparent array directivity is heavily influenced by array element size.

Artificial neural network does better spatiotemporal compressive sampling

NASA Astrophysics Data System (ADS)

Lee, Soo-Young; Hsu, Charles; Szu, Harold

2012-06-01

Spatiotemporal sparseness is generated naturally by human visual system based on artificial neural network modeling of associative memory. Sparseness means nothing more and nothing less than the compressive sensing achieves merely the information concentration. To concentrate the information, one uses the spatial correlation or spatial FFT or DWT or the best of all adaptive wavelet transform (cf. NUS, Shen Shawei). However, higher dimensional spatiotemporal information concentration, the mathematics can not do as flexible as a living human sensory system. The reason is obviously for survival reasons. The rest of the story is given in the paper.

Modelling of the internal dynamics and density in a tens of joules plasma focus device

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

Marquez, Ariel; Gonzalez, Jose; Tarifeno-Saldivia, Ariel

2012-01-15

Using MHD theory, coupled differential equations were generated using a lumped parameter model to describe the internal behaviour of the pinch compression phase in plasma focus discharges. In order to provide these equations with appropriate initial conditions, the modelling of previous phases was included by describing the plasma sheath as planar shockwaves. The equations were solved numerically, and the results were contrasted against experimental measurements performed on the device PF-50J. The model is able to predict satisfactorily the timing and the radial electron density profile at the maximum compression.

Second Generation Models for Strain-Based Design

DOT National Transportation Integrated Search

2011-08-30

This project covers the development of tensile strain design models which form a key part of the strain-based design of pipelines. The strain-based design includes at least two limit states, tensile rupture, and compressive buckling. The tensile stra...

SATELLITE PLASMA SHEATH ANOMALIES,

DTIC Science & Technology

Contents: Experimental Studies of the Kraus Effect Plasma Sheath and Screening around a Rapidly Moving Body Plasma Compression EEffects Produced...Kraus Effect Interaction of West Ford Needles with Earth’s Magnetosphere The Generation of Electromagnetic Waves in the Wake of a Satellite

Characteristics and risks of secondary pollutants generation during compression and transfer of municipal solid waste in Shanghai.

PubMed

Wang, Xiaoyuan; Xie, Bing; Wu, Dong; Hassan, Muhammad; Huang, Changying

2015-09-01

The generation and seasonal variations of secondary pollutants were investigated during three municipal solid waste (MSW) compression and transfer in Shanghai, China. The results showed that the raw wastewater generated from three MSW transfer stations had pH of 4.2-6.0, COD 40,000-70,000mg/L, BOD5 15,000-25,000mg/L, ammonia nitrogen (NH3-N) 400-700mg/L, total nitrogen (TN) 600-1500mg/L, total phosphorus (TP) 50-200mg/L and suspended solids (SS) 1000-80,000mg/L. The pH, COD, BOD5 and NH3-N did not show regular change throughout the year while the concentration of TN, TP and SS were higher in summer and autumn. The animal and vegetable oil content was extremely high. The average produced raw wastewater of three transfer stations ranged from 2.3% to 8.4% of total refuse. The major air pollutants of H2S 0.01-0.17mg/m(3), NH3 0.75-1.8mg/m(3) in transfer stations, however, the regular seasonal change was not discovered. During the transfer process, the generated leachate in container had pH of 5.7-6.4, SS of 9120-32,475mg/L. The COD and BOD5 were 41,633-89,060mg/L and 18,116-34,130mg/L respectively, higher than that in the compress process. The concentration of NH3-N and TP were 587-1422mg/L and 80-216mg/L, respectively, and both increased during transfer process. H2S, VOC, CH4 and NH3 were 0.4-4mg/m(3), 7-19mg/m(3), 0-3.4% and 1-4mg/m(3), respectively. The PCA analysis showed that the production of secondary pollutants is closely related to temperature, especially CH4. Therefore, avoiding high temperature is a key means of reducing the production of gaseous pollutants. And above all else, refuse classification in source, deodorization and anti-acid corrosion are the important processes to control the secondary pollutants during compression and transfer of MSW. Copyright © 2015 Elsevier Ltd. All rights reserved.

A massively parallel adaptive scheme for melt migration in geodynamics computations

NASA Astrophysics Data System (ADS)

Dannberg, Juliane; Heister, Timo; Grove, Ryan

2016-04-01

Melt generation and migration are important processes for the evolution of the Earth's interior and impact the global convection of the mantle. While they have been the subject of numerous investigations, the typical time and length-scales of melt transport are vastly different from global mantle convection, which determines where melt is generated. This makes it difficult to study mantle convection and melt migration in a unified framework. In addition, modelling magma dynamics poses the challenge of highly non-linear and spatially variable material properties, in particular the viscosity. We describe our extension of the community mantle convection code ASPECT that adds equations describing the behaviour of silicate melt percolating through and interacting with a viscously deforming host rock. We use the original compressible formulation of the McKenzie equations, augmented by an equation for the conservation of energy. This approach includes both melt migration and melt generation with the accompanying latent heat effects, and it incorporates the individual compressibilities of the solid and the fluid phase. For this, we derive an accurate and stable Finite Element scheme that can be combined with adaptive mesh refinement. This is particularly advantageous for this type of problem, as the resolution can be increased in mesh cells where melt is present and viscosity gradients are high, whereas a lower resolution is sufficient in regions without melt. Together with a high-performance, massively parallel implementation, this allows for high resolution, 3d, compressible, global mantle convection simulations coupled with melt migration. Furthermore, scalable iterative linear solvers are required to solve the large linear systems arising from the discretized system. Finally, we present benchmarks and scaling tests of our solver up to tens of thousands of cores, show the effectiveness of adaptive mesh refinement when applied to melt migration and compare the compressible and incompressible formulation. We then apply our software to large-scale 3d simulations of melting and melt transport in mantle plumes interacting with the lithosphere. Our model of magma dynamics provides a framework for modelling processes on different scales and investigating links between processes occurring in the deep mantle and melt generation and migration. The presented implementation is available online under an Open Source license together with an extensive documentation.

Nd:YAP laser pulse compression by three-stage transient stimulated Brillouin and Raman scattering

NASA Astrophysics Data System (ADS)

Kubeček, V.; Hamal, K.; Procházka, I.; Buzelis, R.; Girdauskas, V.; Dementiev, A.

1991-08-01

There is a continuous effort to generate stable, powerful picosecond laser pulses for application in spectroscopy, nonlinear optics and parametric light generation, as well. One of the possible methods is the compression of longer nanosecond laser pulses by stimulated Brillouin and stimulated Raman scattering. The advantages of such a technique, in comparison to the used mode locked picosecond lasers, are as follows: the absence of the active and/or passive mode lockers used to generate a train of picosecond pulses, and the absence of a fast electrooptical shutter used to select a single pulse from a train of pulses. The application of stimulated Brillouin and stimulated Raman scattering permits to generate picosecond pulses in the wavelength regions not covered by mode locked lasers. Of special interest is the wavelength region of 0·8 μm, which may be amplified by the attractive Titanium Sapphire lasers. In this paper we are summarizing our results in theoretical modelling and in real generation of picosecond pulses by means of cascaded stimulated Brillouin and Raman scattering. The models of scattering processes have been investigated. The stable generation of 5, 7, 3 picosecond pulses have been optimized for the wavelengths of 0·8, 0·64 and 0·54 μm, respectively. In all these cases, the pulses exhibited the far field pattern close to Gaussian, with the pulse energy ranging from 0·2 to 1 mJ.

Foam property tests to evaluate the potential for longwall shield dust control.

PubMed

Reed, W R; Beck, T W; Zheng, Y; Klima, S; Driscoll, J

2018-01-01

Tests were conducted to determine properties of four foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with the Mine Safety and Health Administration's lower coal mine respirable dust standard of 1.5 mg/m 3 . Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used low-pressure air generated by a blower and water pressure using a foam generator developed by the U.S. National Institute for Occupational Safety and Health. Foam property tests, consisting of a foam expansion ratio test and a water drainage test, were conducted to classify foams. Compressed-air-generated foams tended to have low expansion ratios, from 10 to 19, with high water drainage. Blower-air-generated foams had higher foam expansion ratios, from 30 to 60, with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The test results eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control.

Foam property tests to evaluate the potential for longwall shield dust control

PubMed Central

Reed, W.R.; Beck, T.W.; Zheng, Y.; Klima, S.; Driscoll, J.

2018-01-01

Tests were conducted to determine properties of four foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with the Mine Safety and Health Administration’s lower coal mine respirable dust standard of 1.5 mg/m3. Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used low-pressure air generated by a blower and water pressure using a foam generator developed by the U.S. National Institute for Occupational Safety and Health. Foam property tests, consisting of a foam expansion ratio test and a water drainage test, were conducted to classify foams. Compressed-air-generated foams tended to have low expansion ratios, from 10 to 19, with high water drainage. Blower-air-generated foams had higher foam expansion ratios, from 30 to 60, with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The test results eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control. PMID:29416179

Three Dimensional Compressible Turbulent Flow Computations for a Diffusing S-Duct With/Without Vortex Generators

NASA Technical Reports Server (NTRS)

Cho, Soo-Yong; Greber, Isaac

1994-01-01

Numerical investigations on a diffusing S-duct with/without vortex generators and a straight duct with vortex generators are presented. The investigation consists of solving the full three-dimensional unsteady compressible mass averaged Navier-Stokes equations. An implicit finite volume lower-upper time marching code (RPLUS3D) has been employed and modified. A three-dimensional Baldwin-Lomax turbulence model has been modified in conjunction with the flow physics. A model for the analysis of vortex generators in a fully viscous subsonic internal flow is evaluated. A vortical structure for modeling the shed vortex is used as a source term in the computation domain. The injected vortex paths in the straight duct are compared with the analysis by two kinds of prediction models. The flow structure by the vortex generators are investigated along the duct. Computed results of the flow in a circular diffusing S-duct provide an understanding of the flow structure within a typical engine inlet system. These are compared with the experimental wall static-pressure, static- and total-pressure field, and secondary velocity profiles. Additionally, boundary layer thickness, skin friction values, and velocity profiles in wall coordinates are presented. In order to investigate the effect of vortex generators, various vortex strengths are examined in this study. The total-pressure recovery and distortion coefficients are obtained at the exit of the S-duct. The numerical results clearly depict the interaction between the low velocity flow by the flow separation and the injected vortices.

Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field

NASA Astrophysics Data System (ADS)

Fujioka, Shinsuke; Arikawa, Yasunobu; Kojima, Sadaoki; Johzaki, Tomoyuki; Nagatomo, Hideo; Sawada, Hiroshi; Lee, Seung Ho; Shiroto, Takashi; Ohnishi, Naofumi; Morace, Alessio; Vaisseau, Xavier; Sakata, Shohei; Abe, Yuki; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Shigemori, Keisuke; Hironaka, Yoichiro; Zhang, Zhe; Sunahara, Atsushi; Ozaki, Tetsuo; Sakagami, Hitoshi; Mima, Kunioki; Fujimoto, Yasushi; Yamanoi, Kohei; Norimatsu, Takayoshi; Tokita, Shigeki; Nakata, Yoshiki; Kawanaka, Junji; Jitsuno, Takahisa; Miyanaga, Noriaki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kondo, Kotaro; Bailly-Grandvaux, Mathieu; Bellei, Claudio; Santos, João Jorge; Azechi, Hiroshi

2016-05-01

A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKO-XII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >109. Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused by imploding plasma. Following the above improvements, conversion of 13% of the LFEX laser energy to a low energy portion of the REB, whose slope temperature is 0.7 MeV, which is close to the ponderomotive scaling value, was achieved. To meet the second requirement, the compression of a solid spherical ball with a diameter of 200-μm to form a dense core with an areal density of ˜0.07 g/cm2 was induced by a laser-driven spherically converging shock wave. Converging shock compression is more hydrodynamically stable compared to shell implosion, while a hot spot cannot be generated with a solid ball target. Solid ball compression is preferable also for compressing an external magnetic field to collimate the REB to the fuel core, due to the relatively small magnetic Reynolds number of the shock compressed region. To meet the third requirement, we have generated a strong kilo-tesla magnetic field using a laser-driven capacitor-coil target. The strength and time history of the magnetic field were characterized with proton deflectometry and a B-dot probe. Guidance of the REB using a 0.6-kT field in a planar geometry has been demonstrated at the LULI 2000 laser facility. In a realistic FI scenario, a magnetic mirror is formed between the REB generation point and the fuel core. The effects of the strong magnetic field on not only REB transport but also plasma compression were studied using numerical simulations. According to the transport calculations, the heating efficiency can be improved from 0.4% to 4% by the GEKKO and LFEX laser system by meeting the three requirements described above. This efficiency is scalable to 10% of the heating efficiency by increasing the areal density of the fuel core.