Design and fabrication of a large vertical travel silicon inchworm microactuator for advanced segmented silicon space telescope (ASSIST)

NASA Technical Reports Server (NTRS)

Yang, E.; Dekany, R.; Padin, S.

2003-01-01

The goal of this research is to develop inchworm motor systems capable of simultaneously providing nanometer resolution, high stiffness, large output force, long travel range, and compactness for ultraprecision positioning applications in space.

Compact microwave ion source for industrial applications.

PubMed

Cho, Yong-Sub; Kim, Dae-Il; Kim, Han-Sung; Seol, Kyung-Tae; Kwon, Hyeok-Jung; Hong, In-Seok

2012-02-01

A 2.45 GHz microwave ion source for ion implanters has many good properties for industrial application, such as easy maintenance and long lifetime, and it should be compact for budget and space. But, it has a dc current supply for the solenoid and a rf generator for plasma generation. Usually, they are located on high voltage platform because they are electrically connected with beam extraction power supply. Using permanent magnet solenoid and multi-layer dc break, high voltage deck and high voltage isolation transformer can be eliminated, and the dose rate on targets can be controlled by pulse duty control with semiconductor high voltage switch. Because the beam optics does not change, beam transfer components, such as focusing elements and beam shutter, can be eliminated. It has shown the good performances in budget and space for industrial applications of ion beams.

Compact time- and space-integrating SAR processor: performance analysis

NASA Astrophysics Data System (ADS)

Haney, Michael W.; Levy, James J.; Michael, Robert R., Jr.; Christensen, Marc P.

1995-06-01

Progress made during the previous 12 months toward the fabrication and test of a flight demonstration prototype of the acousto-optic time- and space-integrating real-time SAR image formation processor is reported. Compact, rugged, and low-power analog optical signal processing techniques are used for the most computationally taxing portions of the SAR imaging problem to overcome the size and power consumption limitations of electronic approaches. Flexibility and performance are maintained by the use of digital electronics for the critical low-complexity filter generation and output image processing functions. The results reported for this year include tests of a laboratory version of the RAPID SAR concept on phase history data generated from real SAR high-resolution imagery; a description of the new compact 2D acousto-optic scanner that has a 2D space bandwidth product approaching 106 sports, specified and procured for NEOS Technologies during the last year; and a design and layout of the optical module portion of the flight-worthy prototype.

A 1-Gigabit Memory System on a multi-Chip Module for Space Applications

NASA Technical Reports Server (NTRS)

Louie, Marianne E.; Topliffe, Douglas A.; Alkalai, Leon

1996-01-01

Current spaceborne applications desire compact, low weight, and high capacity data storage systems along with the additional requirement of radiation tolerance. This paper discusses a memory system on a multi-chip module (MCM) that is designed for space applications.

Compact Dual Ion Composition Experiment for space plasmas—CoDICE

NASA Astrophysics Data System (ADS)

Desai, M. I.; Ogasawara, K.; Ebert, R. W.; Allegrini, F.; McComas, D. J.; Livi, S.; Weidner, S. E.

2016-07-01

The Compact Dual Ion Composition Experiment—CoDICE—simultaneously provides high-quality plasma and energetic ion composition measurements over six decades in energy in a wide variety of space plasma environments. CoDICE measures two critical ion populations in space plasmas: (1) Elemental and charge state composition, and 3-D velocity distributions of <10 eV/q-40 keV/q plasma ions; and (2) Elemental composition, energy spectra, and angular distributions of ˜30 keV->10 MeV energetic ions. CoDICE uses a novel, integrated, common time-of-flight subsystem that provides several advantages over the commonly used separate plasma and energetic ion sensors currently flying on several space missions. These advantages include reduced mass and volume compared to two separate instruments, reduced shielding in high-radiation environments, and simplified spacecraft interface and accommodation requirements. This paper describes the operation principles, electro-optic simulation results and applies the CoDICE concept for measuring plasma and energetic ion populations in Jupiter's magnetosphere.

AO corrected satellite imaging from Mount Stromlo

NASA Astrophysics Data System (ADS)

Bennet, F.; Rigaut, F.; Price, I.; Herrald, N.; Ritchie, I.; Smith, C.

2016-07-01

The Research School of Astronomy and Astrophysics have been developing adaptive optics systems for space situational awareness. As part of this program we have developed satellite imaging using compact adaptive optics systems for small (1-2 m) telescopes such as those operated by Electro Optic Systems (EOS) from the Mount Stromlo Observatory. We have focused on making compact, simple, and high performance AO systems using modern high stroke high speed deformable mirrors and EMCCD cameras. We are able to track satellites down to magnitude 10 with a Strehl in excess of 20% in median seeing.

Low-Dimensional Statistics of Anatomical Variability via Compact Representation of Image Deformations.

PubMed

Zhang, Miaomiao; Wells, William M; Golland, Polina

2016-10-01

Using image-based descriptors to investigate clinical hypotheses and therapeutic implications is challenging due to the notorious "curse of dimensionality" coupled with a small sample size. In this paper, we present a low-dimensional analysis of anatomical shape variability in the space of diffeomorphisms and demonstrate its benefits for clinical studies. To combat the high dimensionality of the deformation descriptors, we develop a probabilistic model of principal geodesic analysis in a bandlimited low-dimensional space that still captures the underlying variability of image data. We demonstrate the performance of our model on a set of 3D brain MRI scans from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Our model yields a more compact representation of group variation at substantially lower computational cost than models based on the high-dimensional state-of-the-art approaches such as tangent space PCA (TPCA) and probabilistic principal geodesic analysis (PPGA).

Cryocoolers developments at Thales Cryogenics enabling compact remote sensing

NASA Astrophysics Data System (ADS)

Benschop, A.; van de Groep, W.; Mullié, J.; Willems, D.; Clesca, O.; Griot, R.; Martin, J.-Y.

2010-10-01

Thales Cryogenics (TCBV) has an extensive background in developing and delivering long-life cryogenic coolers for military, civil and space programs. This cooler range is based on three main compressor concepts: rotary compressors (RM), linear close tolerance contact seals (UP), and linear flexure bearing (LSF/LPT) compressors. The main differences - next to the different conceptual designs - between these products are their masses and Mean Time To Failure (MTTF) and the availability prediction of a single unit. New developments at Thales Cryogenics enabling compact long lifetime coolers - with an MTTF up to 50.000 hrs - will be outlined. In addition new developments for miniature cooler drive electronics with high temperature stability and power density will be described. These new cooler developments could be of particular interest for space missions where lower costs and mass are identified as important selection criteria. The developed compressors are originally connected to Stirling cold fingers that can directly be interfaced to different sizes of available dewars. Next to linear coolers, Thales Cryogenics has compact rotary coolers in its product portfolio. Though having a higher exported vibration level and a more limited MTTF of around 8.000 to 10.000 hours, their compactness and high efficiency could provide a good alternative for compact cooling of sensors in specific space missions. In this paper an overview of lifetime parameters will be listed versus the impact in the different cooler types. Tests results from both the installed base and the Thales Cryogenics test lab will be presented as well. Next to this differences in operational use for the different types of coolers as well as the outlook for further developments will be discussed.

A compact high repetition rate CO2 coherent Doppler lidar

NASA Technical Reports Server (NTRS)

Alejandro, S.; Frelin, R.; Dix, B.; Mcnicholl, P.

1992-01-01

As part of its program to develop coherent heterodyne detection lidar technology for space, airborne, and ground based applications, the Optical Environment Division of the USAF's Phillips Laboratory developed a compact coherent CO2 TEA lidar system. Although originally conceived as a high altitude balloon borne system, the lidar is presently integrated into a trailer for ground based field measurements of aerosols and wind fields. In this role, it will also serve as a testbed for signal acquisition and processing development for planned future airborne and space based solid state lidar systems. The system has also found significance in new areas of interest to the Air Force such as cloud studies and coherent Differential Absorption Lidar (DIAL) systems.

Compact and mobile high resolution PET brain imager

DOEpatents

Majewski, Stanislaw [Yorktown, VA; Proffitt, James [Newport News, VA

2011-02-08

A brain imager includes a compact ring-like static PET imager mounted in a helmet-like structure. When attached to a patient's head, the helmet-like brain imager maintains the relative head-to-imager geometry fixed through the whole imaging procedure. The brain imaging helmet contains radiation sensors and minimal front-end electronics. A flexible mechanical suspension/harness system supports the weight of the helmet thereby allowing for patient to have limited movements of the head during imaging scans. The compact ring-like PET imager enables very high resolution imaging of neurological brain functions, cancer, and effects of trauma using a rather simple mobile scanner with limited space needs for use and storage.

Super-Compact Laser

NASA Technical Reports Server (NTRS)

1997-01-01

Microcosm, Inc. produced the portable Farfield-2 laser for field applications that require high power pulsed illumination. The compact design was conceived through research at Goddard Space Flight Center on laser instruments for space missions to carry out geoscience studies of Earth. An exclusive license to the key NASA patent for the compact laser design was assigned to Microcosm. The FarField-2 is ideal for field applications, has low power consumption, does not need water cooling or gas supplies, and produces nearly ideal beam quality. The properties of the laser also make it effective over long distances, which is one reason why NASA developed the technology for laser altimeters that can be toted aboard spacecraft. Applications for the FarField-2 include medicine, biology, and materials science and processing, as well as diamond marking, semiconductor line-cutting, chromosome surgery, and fluorescence microscopy.

Development of a compact optical absolute frequency reference for space with 10^-15 instability.

PubMed

Schuldt, Thilo; Döringshoff, Klaus; Kovalchuk, Evgeny V; Keetman, Anja; Pahl, Julia; Peters, Achim; Braxmaier, Claus

2017-02-01

We report on a compact and ruggedized setup for laser frequency stabilization employing Doppler-free spectroscopy of molecular iodine near 532 nm. Using a 30 cm long iodine cell in a triple-pass configuration in combination with noise-canceling detection and residual amplitude modulation control, a frequency instability of 6×10^-15 at 1 s integration time and a Flicker noise floor below 3×10^-15 for integration times between 100 and 1000 s was found. A specific assembly-integration technology was applied for the realization of the spectroscopy setup, ensuring high beam pointing stability and high thermal and mechanical rigidity. The setup was developed with respect to future applications in space, including high-sensitivity interspacecraft interferometry, tests of fundamental physics, and navigation and ranging.

t-topology on the n-dimensional Minkowski space

NASA Astrophysics Data System (ADS)

Agrawal, Gunjan; Shrivastava, Sampada

2009-05-01

In this paper, a topological study of the n-dimensional Minkowski space, n >1, with t-topology, denoted by Mt, has been carried out. This topology, unlike the usual Euclidean one, is more physically appealing being defined by means of the Lorentzian metric. It shares many topological properties with similar candidate topologies and it has the advantage of being first countable. Compact sets of Mt and continuous maps into Mt are studied using the notion of Zeno sequences besides characterizing those sets that have the same subspace topologies induced from the Euclidean and t-topologies on n-dimensional Minkowski space. A necessary and sufficient condition for a compact set in the Euclidean n-space to be compact in Mt is obtained, thereby proving that the n-cube, n >1, as a subspace of Mt, is not compact, while a segment on a timelike line is compact in Mt. This study leads to the nonsimply connectedness of Mt, for n =2. Further, Minkowski space with s-topology has also been dealt with.

Compact Holographic Data Storage

NASA Technical Reports Server (NTRS)

Chao, T. H.; Reyes, G. F.; Zhou, H.

2001-01-01

NASA's future missions would require massive high-speed onboard data storage capability to Space Science missions. For Space Science, such as the Europa Lander mission, the onboard data storage requirements would be focused on maximizing the spacecraft's ability to survive fault conditions (i.e., no loss in stored science data when spacecraft enters the 'safe mode') and autonomously recover from them during NASA's long-life and deep space missions. This would require the development of non-volatile memory. In order to survive in the stringent environment during space exploration missions, onboard memory requirements would also include: (1) survive a high radiation environment (1 Mrad), (2) operate effectively and efficiently for a very long time (10 years), and (3) sustain at least a billion write cycles. Therefore, memory technologies requirements of NASA's Earth Science and Space Science missions are large capacity, non-volatility, high-transfer rate, high radiation resistance, high storage density, and high power efficiency. JPL, under current sponsorship from NASA Space Science and Earth Science Programs, is developing a high-density, nonvolatile and rad-hard Compact Holographic Data Storage (CHDS) system to enable large-capacity, high-speed, low power consumption, and read/write of data in a space environment. The entire read/write operation will be controlled with electrooptic mechanism without any moving parts. This CHDS will consist of laser diodes, photorefractive crystal, spatial light modulator, photodetector array, and I/O electronic interface. In operation, pages of information would be recorded and retrieved with random access and high-speed. The nonvolatile, rad-hard characteristics of the holographic memory will provide a revolutionary memory technology meeting the high radiation challenge facing the Europa Lander mission. Additional information is contained in the original extended abstract.

A SCHOOL FOR ALL SEASONS.

ERIC Educational Resources Information Center

BERGQUIST, ROBERT

THIS REPORT DESCRIBES A HIGH SCHOOL IN CALIFORNIA INCORPORATING FLEXIBILITY TO ACOMMODATE ALMOST ANY FORESEEABLE EDUCATIONAL CHANGE. STUDENTS MOVE IN THE MIDST OF A COMPACT ENVIRONMENT IN WHICH ALMOST EVERY SQUARE FOOT OF SPACE IS USABLE ACADEMIC SPACE. EACH DEPARTMENT SUBCOURT COMPLEX IS SITUATED SO AS TO BRING ALL STUDENTS INTO SOME CONTACT WITH…

ROSA Transfer (for SpaceX CRS-11)

NASA Image and Video Library

2017-04-12

Inside the Space Station Processing Facility high bay at NASA's Kennedy Space Center in Florida, the Roll-Out Solar Array, or ROSA, is being prepared for transfer out of the high bay. ROSA will be delivered to the International Space Station aboard the SpaceX Dragon cargo carrier on the company’s 11th commercial resupply services mission to the space station. ROSA is a new type of solar panel that rolls open in space and is more compact than current rigid panel designs. The ROSA investigation will test deployment and retraction, shape changes when the Earth blocks the sun, and other physical challenges to determine the array's strength and durability.

NEWTON - NEW portable multi-sensor scienTific instrument for non-invasive ON-site characterization of rock from planetary surface and sub-surfaces

NASA Astrophysics Data System (ADS)

Díaz-Michelena, M.; de Frutos, J.; Ordóñez, A. A.; Rivero, M. A.; Mesa, J. L.; González, L.; Lavín, C.; Aroca, C.; Sanz, M.; Maicas, M.; Prieto, J. L.; Cobos, P.; Pérez, M.; Kilian, R.; Baeza, O.; Langlais, B.; Thébault, E.; Grösser, J.; Pappusch, M.

2017-09-01

In space instrumentation, there is currently no instrument dedicated to susceptibly or complete magnetization measurements of rocks. Magnetic field instrument suites are generally vector (or scalar) magnetometers, which locally measure the magnetic field. When mounted on board rovers, the electromagnetic perturbations associated with motors and other elements make it difficult to reap the benefits from the inclusion of such instruments. However, magnetic characterization is essential to understand key aspects of the present and past history of planetary objects. The work presented here overcomes the limitations currently existing in space instrumentation by developing a new portable and compact multi-sensor instrument for ground breaking high-resolution magnetic characterization of planetary surfaces and sub-surfaces. This new technology introduces for the first time magnetic susceptometry (real and imaginary parts) as a complement to existing compact vector magnetometers for planetary exploration. This work aims to solve the limitations currently existing in space instrumentation by means of providing a new portable and compact multi-sensor instrument for use in space, science and planetary exploration to solve some of the open questions on the crustal and more generally planetary evolution within the Solar System.

Air Force space power and thermal management technology - Requirements for the early 21st century

NASA Astrophysics Data System (ADS)

Herrera, Ernest D.; Kuck, Inara

Typical projections for military space power and thermal management technologies have posited requirements for high powered and highly survivable systems. Recent changes in defense needs, however, will require spacecraft that are smaller, lower powered, less survivable, and highly proliferated. Technologies will be developed to provide low cost, ultra-light, high power density, 'smart' conventional power systems. Compact nuclear power systems will also be developed to meet higher power needs.

Evanescent Properties of Optical Diffraction from 2-Dimensional Hexagonal Photonic Crystals and Their Sensor Applications.

PubMed

Liao, Yu-Yang; Chen, Yung-Tsan; Chen, Chien-Chun; Huang, Jian-Jang

2018-04-03

The sensitivity of traditional diffraction grating sensors is limited by the spatial resolution of the measurement setup. Thus, a large space is required to improve sensor performance. Here, we demonstrate a compact hexagonal photonic crystal (PhC) optical sensor with high sensitivity. PhCs are able to diffract optical beams to various angles in azimuthal space. The critical wavelength that satisfies the phase matching or becomes evanescent was used to benchmark the refractive index of a target analyte applied on a PhC sensor. Using a glucose solution as an example, our sensor demonstrated very high sensitivity and a low limit of detection. This shows that the diffraction mechanism of hexagonal photonic crystals can be used for sensors when compact size is a concern.

Structural Stability of Mathematical Models of National Economy

NASA Astrophysics Data System (ADS)

Ashimov, Abdykappar A.; Sultanov, Bahyt T.; Borovskiy, Yuriy V.; Adilov, Zheksenbek M.; Ashimov, Askar A.

2011-12-01

In the paper we test robustness of particular dynamic systems in a compact regions of a plane and a weak structural stability of one dynamic system of high order in a compact region of its phase space. The test was carried out based on the fundamental theory of dynamical systems on a plane and based on the conditions for weak structural stability of high order dynamic systems. A numerical algorithm for testing the weak structural stability of high order dynamic systems has been proposed. Based on this algorithm we assess the weak structural stability of one computable general equilibrium model.

Experiments and analysis of a compact electrothermal thruster

NASA Technical Reports Server (NTRS)

Asmussen, Jes; Whitehair, Stan

1988-01-01

The description and experimental performance of a compact microwave electrothermal thruster (MET) are presented. This thruster uses a coaxial applicator to couple microwave power into a high pressure discharge. Unlike earlier experiments, it uses no fused quartz in the discharge chamber or the nozzle. This allows high temperatures in the discharge chamber without quartz erosion and melting, thereby improving thruster performance and lifetime. The thruster design is compact, enhancing its potential as a space engine. Experimental tests using nitrogen and helium propellants with input powers levels of 200 W to 1.5 kW are presented. Experimental results, which produce energy efficiencies of 20 to 60 percent and specific impulse of 250 to 450 sec, compare favorably to previous experimental MET performance.

High temperature metal purification using a compact portable rf heating and levitation system on the wake shield

NASA Technical Reports Server (NTRS)

Hahs, C. A.

1990-01-01

The Wake Shield Facility (WSF) can provide an ideal vacuum environment for the purification of high temperature metals in space. The Modular Electromagnetic Levitator (MEL), will provide the opportunity to study undercooling of metals in space and allow to determine material properties in space. The battery powered rf levitation and heating system developed for the MEL demonstrated efficiency of 36 percent. This system is being considered to purify metals at temperatures below 3000 C.

BATMAN flies: a compact spectro-imager for space observation

NASA Astrophysics Data System (ADS)

Zamkotsian, Frederic; Ilbert, Olivier; Zoubian, Julien; Delsanti, Audrey; Boissier, Samuel; Lancon, Ariane

2014-08-01

BATMAN flies is a compact spectro-imager based on MOEMS for generating reconfigurable slit masks, and feeding two arms in parallel. The FOV is 25 x 12 arcmin2 for a 1m telescope, in infrared (0.85-1.7μm) and 500-1000 spectral resolution. Unique science cases for Space Observation are reachable with this deep spectroscopic multi-survey instrument: deep survey of high-z galaxies down to H=25 on 5 deg2 with continuum detection and all z>7 candidates at H=26.2 over 5 deg2; deep survey of young stellar clusters in nearby galaxies; deep survey of the Kuiper Belt of ALL known objects down to H=22. Pathfinder towards BATMAN in space is already running with ground-based demonstrators.

High Power LaB6 Plasma Source Performance for the Lockheed Martin Compact Fusion Reactor Experiment

NASA Astrophysics Data System (ADS)

Heinrich, Jonathon

2016-10-01

Lockheed Martin's Compact Fusion Reactor (CFR) concept is a linear encapsulated ring cusp. Due to the complex field geometry, plasma injection into the device requires careful consideration. A high power thermionic plasma source (>0.25MW; >10A/cm2) has been developed with consideration to phase space for optimal coupling. We present the performance of the plasma source, comparison with alternative plasma sources, and plasma coupling with the CFR field configuration. ©2016 Lockheed Martin Corporation. All Rights Reserved.

On dual and three space problems for the compact approximation property

NASA Astrophysics Data System (ADS)

Choi, Changsun; Kim, Ju Myung

2006-11-01

We introduce the properties W*D and BW*D for the dual space of a Banach space. And then solve the dual problem for the compact approximation property (CAP): if X* has the CAP and the W*D, then X has the CAP. Also, we solve the three space problem for the CAP: for example, if M is a closed subspace of a Banach space such that M[perpendicular] is complemented in X* and X* has the W*D, then X has the CAP whenever X/M has the CAP and M has the bounded CAP. Corresponding problems for the bounded compact approximation property are also addressed.

Understanding and optimizing the dual excipient functionality of sodium lauryl sulfate in tablet formulation of poorly water soluble drug: wetting and lubrication.

PubMed

Aljaberi, Ahmad; Chatterji, Ashish; Dong, Zedong; Shah, Navnit H; Malick, Waseem; Singhal, Dharmendra; Sandhu, Harpreet K

2013-01-01

To evaluate and optimize sodium lauryl sulfate (SLS) and magnesium stearate (Mg.St) levels, with respect to dissolution and compaction, in a high dose, poorly soluble drug tablet formulation. A model poorly soluble drug was formulated using high shear aqueous granulation. A D-optimal design was used to evaluate and model the effect of granulation conditions, size of milling screen, SLS and Mg.St levels on tablet compaction and ejection. The compaction profiles were generated using a Presster(©) compaction simulator. Dissolution of the kernels was performed using a USP dissolution apparatus II and intrinsic dissolution was determined using a stationary disk system. Unlike kernels dissolution which failed to discriminate between tablets prepared with various SLS contents, the intrinsic dissolution rate showed that a SLS level of 0.57% was sufficient to achieve the required release profile while having minimal effect on compaction. The formulation factors that affect tablet compaction and ejection were identified and satisfactorily modeled. The design space of best factor setting to achieve optimal compaction and ejection properties was successfully constructed by RSM analysis. A systematic study design helped identify the critical factors and provided means to optimize the functionality of key excipient to design robust drug product.

Studies of PuF sub 6 and transplutonic materials' critical properties for space high power nuclear pumped lasers

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

Gu, A.G.; Miller, M.S.

1991-01-01

All space missions require a reliable, compact source of energy. This paper describes preliminary neutronics studies of pocket'' reactor concepts employing PuF{sub 6} and transplutonic materials as fuels for space high power/energy Nuclear Pumped Lasers (NPLs). Previous research has studied NPL reactor concepts with thin fuel layers, aerosol fuels and gaseous UF{sub 6}. The total reactor volumes for compact reactors with these types of fuels typically range from 3 m{sup 3} to 50 m{sup 3}. By employing PuF{sub 6} and transplutonic fuels at the same low densities, a calculated value for Keff of 1.2 has been achieved for conditions ofmore » 900 K and 5 atm, with total reactor volumes of 1.5 m{sup 3} for PuF{sub 6}, 0.51 m{sup 3} for Am-242m, 0.58 m{sup 3} for Cm-245 and 0.63 m{sup 3} for Cf-249.« less

Solid state neutron dosimeter for space applications

NASA Technical Reports Server (NTRS)

Entine, Gerald; Nagargar, Vivek; Sharif, Daud

1990-01-01

Personnel engaged in space flight are exposed to significant flux of high energy neutrons arising from both primary and secondary sources of ionizing radiation. Presently, there exist no compact neutron sensor capable of being integrated in a flight instrument to provide real time measurement of this radiation flux. A proposal was made to construct such an instrument using special PIN silicon diode which has the property of being insensitive to the other forms of ionizing radiation. Studies were performed to determine the design and construction of a better reading system to allow the PIN diode to be read with high precision. The physics of the device was studied, especially with respect to those factors which affect the sensitivity and reproducibility of the neutron response. This information was then used to develop methods to achieve high sensitivity at low neutron doses. The feasibility was shown of enhancing the PIN diode sensitivity to make possible the measurement of the low doses of neutrons encountered in space flights. The new PIN diode will make possible the development of a very compact, accurate, personal neutron dosimeter.

ComPAQS: a compact concentric UV/visible spectrometer, providing a new tool for air quality monitoring from space

NASA Astrophysics Data System (ADS)

Leigh, Roland J.; Whyte, C.; Cutter, M. A.; Lobb, D. R.; Monks, P. S.

2017-11-01

Under the first phase of the Centre for Earth Observation Instrumentation (CEOI), a breadboard demonstrator of a novel UV/VIS spectrometer has been developed. Using designs from Surrey Satellite Technology Ltd (SSTL) the demonstrator has been constructed and tested at the University of Leicester's Space Research Centre. This spectrometer provides an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. Measurement of atmo spheric compounds with climate change or air quality implications is a key driver for the ground and space-based Earth Observation communities. Techniques using UV/VIS spectroscopy such as DOAS provide measurements of ozone profiles, aerosol optical depth, certain Volatile Organic Compounds, halogenated species, and key air quality parameters including tropospheric nitrogen dioxide. Compact instruments providing the necessary optical performance and spectral resolution are therefore a key enabling technology. The Compact Air Quality Spectrometer (CompAQS) features a concentric arrangement of a spherical meniscus lens, a concave spherical mirror and a suitable curved diffraction grating. This compact design provides efficiency and performance benefits over traditional concepts, improving the precision and spatial resolution available from space borne instruments with limited weight and size budgets. The breadboard spectrometer currently operating at the University of Leicester offers high throughput with a spectral range from 310 to 450 nm at 0.5nm(UV) to 1.0nm (visible) resolution, suitable for DOAS applications. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called `smile' - the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. In this presentation, the design of the spectrometer is detailed, with results from instrument characterisations undertaken at the University of Leicester, including demonstrations of DOAS fits for key air quality species.

Strong consistency of nonparametric Bayes density estimation on compact metric spaces with applications to specific manifolds

PubMed Central

Bhattacharya, Abhishek; Dunson, David B.

2012-01-01

This article considers a broad class of kernel mixture density models on compact metric spaces and manifolds. Following a Bayesian approach with a nonparametric prior on the location mixing distribution, sufficient conditions are obtained on the kernel, prior and the underlying space for strong posterior consistency at any continuous density. The prior is also allowed to depend on the sample size n and sufficient conditions are obtained for weak and strong consistency. These conditions are verified on compact Euclidean spaces using multivariate Gaussian kernels, on the hypersphere using a von Mises-Fisher kernel and on the planar shape space using complex Watson kernels. PMID:22984295

On-chip photonic particle sensor

NASA Astrophysics Data System (ADS)

Singh, Robin; Ma, Danhao; Agarwal, Anu; Anthony, Brian

2018-02-01

We propose an on-chip photonic particle sensor design that can perform particle sizing and counting for various environmental applications. The sensor is based on micro photonic ring resonators that are able to detect the presence of the free space particles through the interaction with their evanescent electric field tail. The sensor can characterize a wide range of the particle size ranging from a few nano meters to micron ( 1 micron). The photonic platform offers high sensitivity, compactness, fast response of the device. Further, FDTD simulations are performed to analyze different particle-light interactions. Such a compact and portable platform, packaged with integrated photonic circuit provides a useful sensing modality in space shuttle and environmental applications.

Compact Microwave Fourier Spectrum Analyzer

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

2009-01-01

A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

Application of powder X-ray diffraction in studying the compaction behavior of bulk pharmaceutical powders.

PubMed

Bandyopadhyay, Rebanta; Selbo, Jon; Amidon, Gregory E; Hawley, Michael

2005-11-01

This study investigates the effects of crystal lattice deformation on the powder X-ray diffraction (PXRD) patterns of compressed polycrystalline specimen (compacts/tablets) made from molecular, crystalline powders. The displacement of molecules and the corresponding adjustment of interplanar distances (d-spacings) between diffracting planes of PNU-288034 and PNU-177553, which have crystal habits with a high aspect ratio favoring preferred orientation during tableting, are demonstrated by shifts in the diffracted peak positions. The direction of shift in diffracted peak positions suggests a reduction of interplanar d-spacing in the crystals of PNU-288034 and PNU-177553 following compaction. There is also a general reduction of peak intensities following compression at the different compressive loads. The lattice strain representing the reduction in d-spacing is proportional to the original d-spacing of the uncompressed sample suggesting that, as with systems that obey a simple Hooke's law relationship, the further apart the planes of atoms/molecules within the lattice are, the easier it is for them to approach each other under compressive stresses. For a third model compound comprising more equant-shaped crystals of PNU-141659, the shift in diffracted peak positions are consistent with an expansion of lattice spacing after compression. This apparent anomaly is supported by the PXRD studies of the bulk powder consisting of fractured crystals where also, the shift in peak position suggests expansion of the lattice planes. Thus the crystals of PNU-141659 may be fracturing under the compressive loads used to produce the compacts. Additional studies are underway to relate the PXRD observations with the bulk tableting properties of these model compounds.

Injection chaining of diode-pumped single-frequency ring lasers for free-space communication

NASA Technical Reports Server (NTRS)

Cheng, E. A. P.; Kane, T. J.; Wallace, R. W.; Cornwell, D. M., Jr.

1991-01-01

A high-power three-stage laser suitable for use in a space communication system has been built. This laser uses three diode-pumped Nd:YAG oscillators coherently combined using the technique of injection chaining. All three oscillators are in one compact and permanently aligned package, and are actively frequency locked to provide CW single frequency output. The three stages provide the redundancy desirable for space communications.

Quantitative analysis of packed and compacted granular systems by x-ray microtomography

NASA Astrophysics Data System (ADS)

Fu, Xiaowei; Milroy, Georgina E.; Dutt, Meenakshi; Bentham, A. Craig; Hancock, Bruno C.; Elliott, James A.

2005-04-01

The packing and compaction of powders are general processes in pharmaceutical, food, ceramic and powder metallurgy industries. Understanding how particles pack in a confined space and how powders behave during compaction is crucial for producing high quality products. This paper outlines a new technique, based on modern desktop X-ray tomography and image processing, to quantitatively investigate the packing of particles in the process of powder compaction and provide great insights on how powder densify during powder compaction, which relate in terms of materials properties and processing conditions to tablet manufacture by compaction. A variety of powder systems were considered, which include glass, sugar, NaCl, with a typical particle size of 200-300 mm and binary mixtures of NaCl-Glass Spheres. The results are new and have been validated by SEM observation and numerical simulations using discrete element methods (DEM). The research demonstrates that XMT technique has the potential in further investigating of pharmaceutical processing and even verifying other physical models on complex packing.

High-Energy Space Propulsion Based on Magnetized Target Fusion

NASA Technical Reports Server (NTRS)

Thio, Y. C. F.; Landrum, D. B.; Freeze, B.; Kirkpatrick, R. C.; Gerrish, H.; Schmidt, G. R.

1999-01-01

Magnetized target fusion is an approach in which a magnetized target plasma is compressed inertially by an imploding material wall. A high energy plasma liner may be used to produce the required implosion. The plasma liner is formed by the merging of a number of high momentum plasma jets converging towards the center of a sphere where two compact toroids have been introduced. Preliminary 3-D hydrodynamics modeling results using the SPHINX code of Los Alamos National Laboratory have been very encouraging and confirm earlier theoretical expectations. The concept appears ready for experimental exploration and plans for doing so are being pursued. In this talk, we explore conceptually how this innovative fusion approach could be packaged for space propulsion for interplanetary travel. We discuss the generally generic components of a baseline propulsion concept including the fusion engine, high velocity plasma accelerators, generators of compact toroids using conical theta pinches, magnetic nozzle, neutron absorption blanket, tritium reprocessing system, shock absorber, magnetohydrodynamic generator, capacitor pulsed power system, thermal management system, and micrometeorite shields.

A heterodyne interferometer for high-performance industrial metrology

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Gohlke, Martin; Weise, Dennis; Johann, Ulrich; Peters, Achim; Braxmaier, Claus

2008-11-01

We developed a compact, fiber-coupled heterodyne interferometer for translation and tilt metrology. Noise levels below 5 pm/√Hz in translation and below 10 nrad/√Hz in tilt measurement, both for frequencies above 10-2 Hz, were demonstrated in lab experiments. While this setup was developed with respect to the LISA (Laser Interferometer Space Antenna) space mission current activities focus on its adaptation for dimensional characterization of ultra-stable materials and industrial metrology. The interferometer is used in high-accuracy dilatometry measuring the coefficient of thermal expansion (CTE) of dimensionally highly stable materials such as carbon-fiber reinforced plastic (CFRP) and Zerodur. The facility offers the possibility to measure the CTE with an accuracy better 10-8/K. We also develop a very compact and quasi-monolithic sensor head utilizing ultra-low expansion glass material which is the basis for a future space-qualifiable interferometer setup and serves as a prototype for a sensor head used in industrial environment. For high resolution 3D profilometry and surface property measurements (i. e. roughness, evenness and roundness), a low-noise (<=1nm/√ Hz) actuator will be implemented which enables a scan of the measurement beam over the surface under investigation.

Lightweight Phase-Change Material For Solar Power

NASA Technical Reports Server (NTRS)

Stark, Philip

1993-01-01

Lightweight panels containing phase-change materials developed for use as heat-storage elements of compact, lightweight, advanced solar dynamic power system. During high insolation, heat stored in panels via latent heat of fusion of phase-change material; during low insolation, heat withdrawn from panels. Storage elements consist mainly of porous carbon-fiber structures imbued with germanium. Developed for use aboard space station in orbit around Earth, also adapted to lightweight, compact, portable solar-power systems for use on Earth.

Blackfolds, plane waves and minimal surfaces

NASA Astrophysics Data System (ADS)

Armas, Jay; Blau, Matthias

2015-07-01

Minimal surfaces in Euclidean space provide examples of possible non-compact horizon geometries and topologies in asymptotically flat space-time. On the other hand, the existence of limiting surfaces in the space-time provides a simple mechanism for making these configurations compact. Limiting surfaces appear naturally in a given space-time by making minimal surfaces rotate but they are also inherent to plane wave or de Sitter space-times in which case minimal surfaces can be static and compact. We use the blackfold approach in order to scan for possible black hole horizon geometries and topologies in asymptotically flat, plane wave and de Sitter space-times. In the process we uncover several new configurations, such as black helicoids and catenoids, some of which have an asymptotically flat counterpart. In particular, we find that the ultraspinning regime of singly-spinning Myers-Perry black holes, described in terms of the simplest minimal surface (the plane), can be obtained as a limit of a black helicoid, suggesting that these two families of black holes are connected. We also show that minimal surfaces embedded in spheres rather than Euclidean space can be used to construct static compact horizons in asymptotically de Sitter space-times.

Inhomogeneous compact extra dimensions

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

Bronnikov, K.A.; Budaev, R.I.; Grobov, A.V.

We show that an inhomogeneous compact extra space possesses two necessary features— their existence does not contradict the observable value of the cosmological constant Λ{sub 4} in pure f ( R ) theory, and the extra dimensions are stable relative to the 'radion mode' of perturbations, the only mode considered. For a two-dimensional extra space, both analytical and numerical solutions for the metric are found, able to provide a zero or arbitrarily small Λ{sub 4}. A no-go theorem has also been proved, that maximally symmetric compact extra spaces are inconsistent with 4D Minkowski space in the framework of pure fmore » ( R ) gravity.« less

Generating GPS activity spaces that shed light upon the mobility habits of older adults: a descriptive analysis.

PubMed

Hirsch, Jana A; Winters, Meghan; Clarke, Philippa; McKay, Heather

2014-12-12

Measuring mobility is critical for understanding neighborhood influences on older adults' health and functioning. Global Positioning Systems (GPS) may represent an important opportunity to measure, describe, and compare mobility patterns in older adults. We generated three types of activity spaces (Standard Deviation Ellipse, Minimum Convex Polygon, Daily Path Area) using GPS data from 95 older adults in Vancouver, Canada. Calculated activity space areas and compactness were compared across sociodemographic and resource characteristics. Area measures derived from the three different approaches to developing activity spaces were highly correlated. Participants who were younger, lived in less walkable neighborhoods, had a valid driver's license, had access to a vehicle, or had physical support to go outside of their homes had larger activity spaces. Mobility space compactness measures also differed by sociodemographic and resource characteristics. This research extends the literature by demonstrating that GPS tracking can be used as a valuable tool to better understand the geographic mobility patterns of older adults. This study informs potential ways to maintain older adult independence by identifying factors that influence geographic mobility.

Fuel Cells

ERIC Educational Resources Information Center

Hawkins, M. D.

1973-01-01

Discusses the theories, construction, operation, types, and advantages of fuel cells developed by the American space programs. Indicates that the cell is an ideal small-scale power source characterized by its compactness, high efficiency, reliability, and freedom from polluting fumes. (CC)

Flattening Property and the Existence of Global Attractors in Banach Space

NASA Astrophysics Data System (ADS)

Aris, Naimah; Maharani, Sitti; Jusmawati, Massalesse; Nurwahyu, Budi

2018-03-01

This paper analyses the existence of global attractor in infinite dimensional system using flattening property. The earlier stage we show the existence of the global attractor in complete metric space by using concept of the ω-limit compact concept with measure of non-compactness methods. Then we show that the ω-limit compact concept is equivalent with the flattening property in Banach space. If we can prove there exist an absorbing set in the system and the flattening property holds, then the global attractor exist in the system.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-08-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer for atmospheric research has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications particularly from space (LEO, GEO orbits) and from HAPs or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at better than 0.5 nm resolution, suitable for a number of typical DOAS applications.

MID-INFRARED EVIDENCE FOR ACCELERATED EVOLUTION IN COMPACT GROUP GALAXIES

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

Walker, Lisa May; Johnson, Kelsey E.; Gallagher, Sarah C.

2010-11-15

Compact galaxy groups are at the extremes of the group environment, with high number densities and low velocity dispersions that likely affect member galaxy evolution. To explore the impact of this environment in detail, we examine the distribution in the mid-infrared (MIR) 3.6-8.0 {mu}m color space of 42 galaxies from 12 Hickson compact groups (HCGs) in comparison with several control samples, including the LVL+SINGS galaxies, interacting galaxies, and galaxies from the Coma Cluster. We find that the HCG galaxies are strongly bimodal, with statistically significant evidence for a gap in their distribution. In contrast, none of the other samples showmore » such a marked gap, and only galaxies in the Coma infall region have a distribution that is statistically consistent with the HCGs in this parameter space. To further investigate the cause of the HCG gap, we compare the galaxy morphologies of the HCG and LVL+SINGS galaxies, and also probe the specific star formation rate (SSFR) of the HCG galaxies. While galaxy morphology in HCG galaxies is strongly linked to position with MIR color space, the more fundamental property appears to be the SSFR, or star formation rate normalized by stellar mass. We conclude that the unusual MIR color distribution of HCG galaxies is a direct product of their environment, which is most similar to that of the Coma infall region. In both cases, galaxy densities are high, but gas has not been fully processed or stripped. We speculate that the compact group environment fosters accelerated evolution of galaxies from star-forming and neutral gas-rich to quiescent and neutral gas-poor, leaving few members in the MIR gap at any time.« less

Effective shielding to measure beam current from an ion source

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

Bayle, H., E-mail: bayle@bergoz.com; Delferrière, O.; Gobin, R.

To avoid saturation, beam current transformers must be shielded from solenoid, quad, and RFQ high stray fields. Good understanding of field distribution, shielding materials, and techniques is required. Space availability imposes compact shields along the beam pipe. This paper describes compact effective concatenated magnetic shields for IFMIF-EVEDA LIPAc LEBT and MEBT and for FAIR Proton Linac injector. They protect the ACCT Current Transformers beyond 37 mT radial external fields. Measurements made at Saclay on the SILHI source are presented.

Compact Full-Field Ion Detector System for SmallSats Beyond LEO

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.; Clark, Pamela E.; McNeil, Roger R.

2014-01-01

NASA Glenn Research Center (GRC) is applying its expertise and facilities in harsh environment instrumentation to develop a Compact Full-Field Ion Detector System (CFIDS). The CFIDS is designed to be an extremely compact, low cost instrument, capable of being flown on a wide variety of deep space platforms, to provide multi-directional, comprehensive (composition, velocity, and direction) in-situ measurements of heavy ions in space plasma environments.

Design, characterization and control of the Unique Mobility Corporation robot

NASA Technical Reports Server (NTRS)

Velasco, Virgilio B., Jr.; Newman, Wyatt S.; Steinetz, Bruce; Kopf, Carlo; Malik, John

1994-01-01

Space and mass are at a premium on any space mission, and thus any machinery designed for space use should be lightweight and compact, without sacrificing strength. It is for this reason that NASA/LeRC contracted Unique Mobility Corporation to exploit their novel actuator designs to build a robot that would advance the present state of technology with respect to these requirements. Custom-designed motors are the key feature of this robot. They are compact, high-performance dc brushless servo motors with a high pole count and low inductance, thus permitting high torque generation and rapid phase commutation. Using a custom-designed digital signal processor-based controller board, the pulse width modulation power amplifiers regulate the fast dynamics of the motor currents. In addition, the programmable digital signal processor (DSP) controller permits implementation of nonlinear compensation algorithms to account for motoring vs. regeneration, torque ripple, and back-EMF. As a result, the motors produce a high torque relative to their size and weight, and can do so with good torque regulation and acceptably high velocity saturation limits. This paper presents the Unique Mobility Corporation robot prototype: its actuators, its kinematic design, its control system, and its experimental characterization. Performance results, including saturation torques, saturation velocities and tracking accuracy tests are included.

High-energy radiation from the relativistic jet of Cygnus X-3

NASA Astrophysics Data System (ADS)

Cerutti, B.; Dubus, G.; Henri, G.

2010-12-01

Cygnus X-3 is an accreting high-mass X-ray binary composed of a Wolf-Rayet star and an unknown compact object, possibly a black hole. The gamma-ray space telescope Fermi found definitive evidence that high-energy emission is produced in this system. We propose a scenario to explain the GeV gamma-ray emission in Cygnus X-3. In this model, energetic electron-positron pairs are accelerated at a specific location in the relativistic jet, possibly related to a recollimation shock, and upscatter the stellar photons to high energies. The comparison with Fermi observations shows that the jet should be inclined close to the line of sight and pairs should not be located within the system. Energetically speaking, a massive compact object is favored. We report also on our investigations of the gamma-ray absorption of GeV photons with the radiation emitted by a standard accretion disk in Cygnus X-3. This study shows that the gamma-ray source should not lie too close to the compact object.

Exact Recovery of Chaotic Systems from Highly Corrupted Data

DTIC Science & Technology

2016-08-01

dimension to reconstruct a state space which preserves the topological properties of the original system. In [CM87, RS92], the authors use the singular...in high dimensional nonlinear functional spaces [Spr94, SL00, LCC04]. In this work, we bring together connections between compressed sensing, splitting... compact , connected attractor Λ and the flow admits a unique so-called “physical" measure µ with supp(µ) = Λ. An invariant probability measure µ for a flow

Linking initial microstructure and local response during quasistatic granular compaction

DOE PAGES

Hurley, R. C.; Lind, J.; Pagan, D. C.; ...

2017-07-24

In this study, we performed experiments combining three-dimensional x-ray diffraction and x-ray computed tomography to explore the relationship between microstructure and local force and strain during quasistatic granular compaction. We found that initial void space around a grain and contact coordination number before compaction can be used to predict regions vulnerable to above-average local force and strain at later stages of compaction. We also found correlations between void space around a grain and coordination number, and between grain stress and maximum interparticle force, at all stages of compaction. Finally, we observed grains that fracture to have an above-average initial localmore » void space and a below-average initial coordination number. In conclusion, our findings provide (1) a detailed description of microstructure evolution during quasistatic granular compaction, (2) an approach for identifying regions vulnerable to large values of strain and interparticle force, and (3) methods for identifying regions of a material with large interparticle forces and coordination numbers from measurements of grain stress and local porosity.« less

Environmental Education Excursions and Proximity to Urban Green Space--Densification in a "Compact City"

ERIC Educational Resources Information Center

Wolsink, Maarten

2016-01-01

The value of urban green space for environmental education fieldwork is empirically investigated in a study among all secondary schools in Amsterdam. The article describes how the proximity of schools to green spaces emerges as a new factor in the "sustainable city" and the "compact city" debate. For fieldwork excursions…

Discovery of Compact Quiescent Galaxies at Intermediate Redshifts in DEEP2

NASA Astrophysics Data System (ADS)

Blancato, Kirsten; Chilingarian, Igor; Damjanov, Ivana; Moran, Sean; Katkov, Ivan

2015-01-01

Compact quiescent galaxies in the redshift range 0.6 < z < 1.1 are the missing link needed to complete the evolutionary histories of these objects from the high redshift z ≥ 2 Universe to the local z ~ 0 Universe. We identify the first intermediate redshift compact quiescent galaxies by searching a sample of 1,089 objects in the DEEP2 Redshift Survey that have multi-band photometry, spectral fitting, and readily available structural parameters. We find 27 compact quiescent candidates between z = 0.6 and z = 1.1 where each candidate galaxy has archival Hubble Space Telescope (HST) imaging and is visually confirmed to be early-type. The candidates have half-light radii ranging from 0.83 < Re,c < 7.14 kpc (median Re,c = 1.77 kpc) and virial masses ranging from 2.2E10 < Mdyn < 5.6E11 Msun (median Mdyn = 7.7E10 Msun). Of our 27 compact quiescent candidates, 13 are truly compact with sizes at most half of the size of their z ~ 0 counterparts of the same mass. In addition to their structural properties bridging the gap between their high and low redshift counterparts, our sample of intermediate redshift quiescent galaxies span a large range of ages but is drawn from two distinct epochs of galaxy formation: formation at z > 2 which suggests these objects may be the relics of the observed high redshift compact galaxies and formation at z ≤ 2 which suggests there is an additional population of more recently formed massive compact galaxies. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

Probing Planckian Corrections at the Horizon Scale with LISA Binaries

NASA Astrophysics Data System (ADS)

Maselli, Andrea; Pani, Paolo; Cardoso, Vitor; Abdelsalhin, Tiziano; Gualtieri, Leonardo; Ferrari, Valeria

2018-02-01

Several quantum-gravity models of compact objects predict microscopic or even Planckian corrections at the horizon scale. We explore the possibility of measuring two model-independent, smoking-gun effects of these corrections in the gravitational waveform of a compact binary, namely, the absence of tidal heating and the presence of tidal deformability. For events detectable by the future space-based interferometer LISA, we show that the effect of tidal heating dominates and allows one to constrain putative corrections down to the Planck scale. The measurement of the tidal Love numbers with LISA is more challenging but, in optimistic scenarios, it allows us to constrain the compactness of a supermassive exotic compact object down to the Planck scale. Our analysis suggests that highly spinning, supermassive binaries at 1-20 Gpc provide unparalleled tests of quantum-gravity effects at the horizon scale.

Probing Planckian Corrections at the Horizon Scale with LISA Binaries.

PubMed

Maselli, Andrea; Pani, Paolo; Cardoso, Vitor; Abdelsalhin, Tiziano; Gualtieri, Leonardo; Ferrari, Valeria

2018-02-23

Several quantum-gravity models of compact objects predict microscopic or even Planckian corrections at the horizon scale. We explore the possibility of measuring two model-independent, smoking-gun effects of these corrections in the gravitational waveform of a compact binary, namely, the absence of tidal heating and the presence of tidal deformability. For events detectable by the future space-based interferometer LISA, we show that the effect of tidal heating dominates and allows one to constrain putative corrections down to the Planck scale. The measurement of the tidal Love numbers with LISA is more challenging but, in optimistic scenarios, it allows us to constrain the compactness of a supermassive exotic compact object down to the Planck scale. Our analysis suggests that highly spinning, supermassive binaries at 1-20 Gpc provide unparalleled tests of quantum-gravity effects at the horizon scale.

The Pearson-Readhead Survey of Compact Extragalactic Radio Sources from Space. II. Analysis of Source Properties

NASA Astrophysics Data System (ADS)

Lister, M. L.; Tingay, S. J.; Preston, R. A.

2001-06-01

We have performed a multidimensional correlation analysis on the observed properties of a statistically complete core-selected sample of compact radio-loud active galactic nuclei based on data from the VLBI Space Observing Programme (Paper I) and previously published studies. Our sample is drawn from the well-studied Pearson-Readhead (PR) survey and is ideally suited for investigating the general effects of relativistic beaming in compact radio sources. In addition to confirming many previously known correlations, we have discovered several new trends that lend additional support to the beaming model. These trends suggest that the most highly beamed sources in core-selected samples tend to have (1) high optical polarizations; (2) large parsec- kiloparsec-scale jet misalignments; (3) prominent VLBI core components; (4) one-sided, core, or halo radio morphology on kiloparsec scales; (5) narrow emission line equivalent widths; and (6) a strong tendency for intraday variability at radio wavelengths. We have used higher resolution space and ground-based VLBI maps to confirm the bimodality of the jet misalignment distribution for the PR survey and find that the sources with aligned parsec- and kiloparsec-scale jets generally have arcsecond-scale radio emission on both sides of the core. The aligned sources also have broader emission line widths. We find evidence that the BL Lacertae objects in the PR survey are all highly beamed and have very similar properties to the high optically polarized quasars, with the exception of smaller redshifts. A cluster analysis on our data shows that after partialing out the effects of redshift, the luminosities of our sample objects in various wave bands are generally well correlated with each other but not with other source properties.

A New Family of Compact High Order Coupled Time-Space Unconditionally Stable Vertical Advection Schemes

NASA Astrophysics Data System (ADS)

Lemarié, F.; Debreu, L.

2016-02-01

Recent papers by Shchepetkin (2015) and Lemarié et al. (2015) have emphasized that the time-step of an oceanic model with an Eulerian vertical coordinate and an explicit time-stepping scheme is very often restricted by vertical advection in a few hot spots (i.e. most of the grid points are integrated with small Courant numbers, compared to the Courant-Friedrichs-Lewy (CFL) condition, except just few spots where numerical instability of the explicit scheme occurs first). The consequence is that the numerics for vertical advection must have good stability properties while being robust to changes in Courant number in terms of accuracy. An other constraint for oceanic models is the strict control of numerical mixing imposed by the highly adiabatic nature of the oceanic interior (i.e. mixing must be very small in the vertical direction below the boundary layer). We examine in this talk the possibility of mitigating vertical Courant-Friedrichs-Lewy (CFL) restriction, while avoiding numerical inaccuracies associated with standard implicit advection schemes (i.e. large sensitivity of the solution on Courant number, large phase delay, and possibly excess of numerical damping with unphysical orientation). Most regional oceanic models have been successfully using fourth order compact schemes for vertical advection. In this talk we present a new general framework to derive generic expressions for (one-step) coupled time and space high order compact schemes (see Daru & Tenaud (2004) for a thorough description of coupled time and space schemes). Among other properties, we show that those schemes are unconditionally stable and have very good accuracy properties even for large Courant numbers while having a very reasonable computational cost. To our knowledge no unconditionally stable scheme with such high order accuracy in time and space have been presented so far in the literature. Furthermore, we show how those schemes can be made monotonic without compromising their stability properties.

Conformal field theories and compact curves in moduli spaces

NASA Astrophysics Data System (ADS)

Donagi, Ron; Morrison, David R.

2018-05-01

We show that there are many compact subsets of the moduli space M g of Riemann surfaces of genus g that do not intersect any symmetry locus. This has interesting implications for N=2 supersymmetric conformal field theories in four dimensions.

Compact atomic clocks and stabilised laser for space applications

NASA Astrophysics Data System (ADS)

Mileti, Gaetano; Affolderbach, Christoph; Matthey-de-l'Endroit, Renaud

2016-07-01

We present our developments towards next generation compact vapour-cell based atomic frequency standards using a tunable laser diode instead of a traditional discharge lamp. The realisation of two types of Rubidium clocks addressing specific applications is in progress: high performance frequency standards for demanding applications such as satellite navigation, and chip-scale atomic clocks, allowing further miniaturisation of the system. The stabilised laser source constitutes the main technological novelty of these new standards, allowing a more efficient preparation and interrogation of the atoms and hence an improvement of the clock performances. However, before this key component may be employed in a commercial and ultimately in a space-qualified instrument, further studies are necessary to demonstrate their suitability, in particular concerning their reliability and long-term operation. The talk will present our preliminary investigations on this subject. The stabilised laser diode technology developed for our atomic clocks has several other applications on ground and in space. We will conclude our talk by illustrating this for the example of a recently completed ESA project on a 1.6 microns wavelength reference for a future space-borne Lidar. This source is based on a Rubidium vapour cell providing the necessary stability and accuracy, while a second harmonic generator and a compact optical comb generated from an electro-optic modulator allow to transfer these properties from the Rubidium wavelength (780nm) to the desired spectral range.

Adaptive Controller for Compact Fourier Transform Spectrometer with Space Applications

NASA Astrophysics Data System (ADS)

Keymeulen, D.; Yiu, P.; Berisford, D. F.; Hand, K. P.; Carlson, R. W.; Conroy, M.

2014-12-01

Here we present noise mitigation techniques developed as part of an adaptive controller for a very compact Compositional InfraRed Interferometric Spectrometer (CIRIS) implemented on a stand-alone field programmable gate array (FPGA) architecture with emphasis on space applications in high radiation environments such as Europa. CIRIS is a novel take on traditional Fourier Transform Spectrometers (FTS) and replaces linearly moving mirrors (characteristic of Michelson interferometers) with a constant-velocity rotating refractor to variably phase shift and alter the path length of incoming light. The design eschews a monochromatic reference laser typically used for sampling clock generation and instead utilizes constant time-sampling via internally generated clocks. This allows for a compact and robust device, making it ideal for spaceborne measurements in the near-IR to thermal-IR band (2-12 µm) on planetary exploration missions. The instrument's embedded microcontroller is implemented on a VIRTEX-5 FPGA and a PowerPC with the aim of sampling the instrument's detector and optical rotary encoder in order to construct interferograms. Subsequent onboard signal processing provides spectral immunity from the noise effects introduced by the compact design's removal of a reference laser and by the radiation encountered during space flight to destinations such as Europa. A variety of signal processing techniques including resampling, radiation peak removal, Fast Fourier Transform (FFT), spectral feature alignment, dispersion correction and calibration processes are applied to compose the sample spectrum in real-time with signal-to-noise-ratio (SNR) performance comparable to laser-based FTS designs in radiation-free environments. The instrument's FPGA controller is demonstrated with the FTS to characterize its noise mitigation techniques and highlight its suitability for implementation in space systems.

A compact roller-gear pitch-yaw joint module: Design and control issues

NASA Technical Reports Server (NTRS)

Dohring, Mark E.; Anderson, William J.; Newman, Wyatt S.; Rohn, Douglas A.

1993-01-01

Robotic systems have been proposed as a means of accomplishing assembly and maintenance tasks in space. The desirable characteristics of these systems include compact size, low mass, high load capacity, and programmable compliance to improve assembly performance. In addition, the mechanical system must transmit power in such a way as to allow high performance control of the system. Efficiency, linearity, low backlash, low torque ripple, and low friction are all desirable characteristics. This work presents a pitch-yaw joint module designed and built to address these issues. Its effectiveness as a two degree-of-freedom manipulator using natural admittance control, a method of force control, is demonstrated.

Parallel Implementation of a High Order Implicit Collocation Method for the Heat Equation

NASA Technical Reports Server (NTRS)

Kouatchou, Jules; Halem, Milton (Technical Monitor)

2000-01-01

We combine a high order compact finite difference approximation and collocation techniques to numerically solve the two dimensional heat equation. The resulting method is implicit arid can be parallelized with a strategy that allows parallelization across both time and space. We compare the parallel implementation of the new method with a classical implicit method, namely the Crank-Nicolson method, where the parallelization is done across space only. Numerical experiments are carried out on the SGI Origin 2000.

Active phase correction of high resolution silicon photonic arrayed waveguide gratings

DOE PAGES

Gehl, M.; Trotter, D.; Starbuck, A.; ...

2017-03-10

Arrayed waveguide gratings provide flexible spectral filtering functionality for integrated photonic applications. Achieving narrow channel spacing requires long optical path lengths which can greatly increase the footprint of devices. High index contrast waveguides, such as those fabricated in silicon-on-insulator wafers, allow tight waveguide bends which can be used to create much more compact designs. Both the long optical path lengths and the high index contrast contribute to significant optical phase error as light propagates through the device. Thus, silicon photonic arrayed waveguide gratings require active or passive phase correction following fabrication. We present the design and fabrication of compact siliconmore » photonic arrayed waveguide gratings with channel spacings of 50, 10 and 1 GHz. The largest device, with 11 channels of 1 GHz spacing, has a footprint of only 1.1 cm 2. Using integrated thermo-optic phase shifters, the phase error is actively corrected. We present two methods of phase error correction and demonstrate state-of-the-art cross-talk performance for high index contrast arrayed waveguide gratings. As a demonstration of possible applications, we perform RF channelization with 1 GHz resolution. In addition, we generate unique spectral filters by applying non-zero phase offsets calculated by the Gerchberg Saxton algorithm.« less

Active phase correction of high resolution silicon photonic arrayed waveguide gratings.

PubMed

Gehl, M; Trotter, D; Starbuck, A; Pomerene, A; Lentine, A L; DeRose, C

2017-03-20

Arrayed waveguide gratings provide flexible spectral filtering functionality for integrated photonic applications. Achieving narrow channel spacing requires long optical path lengths which can greatly increase the footprint of devices. High index contrast waveguides, such as those fabricated in silicon-on-insulator wafers, allow tight waveguide bends which can be used to create much more compact designs. Both the long optical path lengths and the high index contrast contribute to significant optical phase error as light propagates through the device. Therefore, silicon photonic arrayed waveguide gratings require active or passive phase correction following fabrication. Here we present the design and fabrication of compact silicon photonic arrayed waveguide gratings with channel spacings of 50, 10 and 1 GHz. The largest device, with 11 channels of 1 GHz spacing, has a footprint of only 1.1 cm². Using integrated thermo-optic phase shifters, the phase error is actively corrected. We present two methods of phase error correction and demonstrate state-of-the-art cross-talk performance for high index contrast arrayed waveguide gratings. As a demonstration of possible applications, we perform RF channelization with 1 GHz resolution. Additionally, we generate unique spectral filters by applying non-zero phase offsets calculated by the Gerchberg Saxton algorithm.

Compact Full-Field Ion Detector System for CubeSat Science Beyond LEO

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.; Clark, Pamela E.

2013-01-01

NASA Glenn Research Center (GRC) is applying its expertise and facilities in harsh environment instrumentation to develop a Compact Full-Field Ion Detector System (CFIDS). The CFIDS is designed to be an extremely compact, low cost instrument, capable of being flown on a wide variety of deep space platforms, to provide comprehensive (composition, velocity, and direction) in situ measurements of heavy ions in space plasma environments with higher fidelity, than previously available.

Free-space laser communication technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 11, 12, 1988

NASA Astrophysics Data System (ADS)

Koepf, Gerhard A.; Begley, David L.

1988-01-01

The present conference discusses topics in free-space laser communications, laser link characteristics, satellite laser communication systems, optoelectronic components for laser communications, and space laser subsystem technologies. Attention is given to Space Station-based deep-space communication experiments, the application of intersatellite links to operational satellite systems, high-power 0.87 micron channel substrate planar lasers for spaceborne communications, a ground experiment using a CO2 laser transceiver for free-space communications, studies of laser ranging to the TOPEX satellite, diffraction-limited tracking for space communications, and the compact implementation of a real-time, acoustooptic SAR processor.

Fiber-based Coherent Lidar for Target Ranging, Velocimetry, and Atmospheric Wind Sensing

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Pierrottet, Diego

2006-01-01

By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable lidar suitable for operation in a space environment is being developed.

Design and testing of focusing magnets for a compact electron linac

NASA Astrophysics Data System (ADS)

Chen, Qushan; Qin, Bin; Liu, Kaifeng; Liu, Xu; Fu, Qiang; Tan, Ping; Hu, Tongning; Pei, Yuanji

2015-10-01

Solenoid field errors have great influence on electron beam qualities. In this paper, design and testing of high precision solenoids for a compact electron linac is presented. We proposed an efficient and practical method to solve the peak field of the solenoid for relativistic electron beams based on the reduced envelope equation. Beam dynamics involving space charge force were performed to predict the focusing effects. Detailed optimization methods were introduced to achieve an ultra-compact configuration as well as high accuracy, with the help of the POISSON and OPERA packages. Efforts were attempted to restrain system errors in the off-line testing, which showed the short lens and the main solenoid produced a peak field of 0.13 T and 0.21 T respectively. Data analysis involving central and off axes was carried out and demonstrated that the testing results fitted well with the design.

Space Shuttle Payload Information Source

NASA Technical Reports Server (NTRS)

Griswold, Tom

2000-01-01

The Space Shuttle Payload Information Source Compact Disk (CD) is a joint NASA and USA project to introduce Space Shuttle capabilities, payload services and accommodations, and the payload integration process. The CD will be given to new payload customers or to organizations outside of NASA considering using the Space Shuttle as a launch vehicle. The information is high-level in a visually attractive format with a voice over. The format is in a presentation style plus 360 degree views, videos, and animation. Hyperlinks are provided to connect to the Internet for updates and more detailed information on how payloads are integrated into the Space Shuttle.

Gravitationally Focused Dark Matter around Compact Stars

NASA Astrophysics Data System (ADS)

Bromley, Benjamin C.

2011-12-01

If dark matter self-annihilates then it may produce an observable signal when its density is high. The details depend on the intrinsic properties of dark matter and how it clusters in space. For example, the density profile of some dark matter candidates may rise steeply enough toward the Galactic Center that self-annihilation may produce detectable γ-ray emission. Here, we discuss the possibility that an annihilation signal arises near a compact object (e.g., neutron star or black hole) even when the density of dark matter in the neighborhood of the object is uniform. Gravitational focusing produces a local enhancement of density with a profile that falls off approximately as the inverse square-root of distance from the compact star. While geometric dilution may overwhelm the annihilation signal from this local enhancement, magnetic fields tied to the compact object can increase the signal's contrast relative to the background.

Approximations and Solution Estimates in Optimization

DTIC Science & Technology

2016-04-06

comprehensive descriptions of epi-convergence and its connections to variational analysis broadly. Our motivation for going beyond normed linear spaces , which...proper, every closed ball in this metric space is compact and the existence of solutions of such optimal fitting problems is more easily established...lsc-fcns(X), dl(fν , f) → 0 implies that fν epi-converges to f. We recall that a metric space is proper if every closed ball in that space is compact

The long flow to freedom

DOE PAGES

Aharony, Ofer; Razamat, Shlomo S.; Seiberg, Nathan; ...

2017-02-10

Two-dimensional field theories do not have a moduli space of vacua. Instead, it is common that their low-energy behavior is a sigma model with a target space. When this target space is compact its renormalization group flow is standard. When it is non-compact the continuous spectrum of operators can change the qualitative behavior. Here we discuss two-dimensional gauge theories with N = (2,2) supersymmetry. We focus on two specific theories, for which we argue that they flow to free chiral multiplets at low energies: the U(1) gauge theory with one flavor (two chiral superfields with charges plus and minus one)more » and a non-zero Fayet-Iliopoulos term, and pure SU( N) gauge theories. We argue that the renormalization group flow of these theories has an interesting order of limits issue. Holding the position on the target space fixed, the space flattens out under the renormalization group. On the other hand, if we first go to infinity on the target space and then perform the renormalization group, we always have a non-trivial space, e.g. a cone with a deficit angle. We explain how to interpret low-energy dualities between theories with non-compact target spaces. As a result, we expect a similar qualitative behavior also for other non-compact sigma models, even when they do not flow to free theories.« less

A Search for Nontoroidal Topological Lensing in the Sloan Digital Sky Survey Quasar Catalog

NASA Astrophysics Data System (ADS)

Fujii, Hirokazu; Yoshii, Yuzuru

2013-08-01

Flat space models with multiply connected topology, which have compact dimensions, are tested against the distribution of high-redshift (z >= 4) quasars of the Sloan Digital Sky Survey (SDSS). When the compact dimensions are smaller in size than the observed universe, topological lensing occurs, in which multiple images of single objects (ghost images) are observed. We improve on the recently introduced method to identify ghost images by means of four-point statistics. Our method is valid for any of the 17 multiply connected flat models, including nontoroidal ones that are compacted by screw motions or glide reflection. Applying the method to the data revealed one possible case of topological lensing caused by sixth-turn screw motion, however, it is consistent with the simply connected model by this test alone. Moreover, simulations suggest that we cannot exclude the other space models despite the absence of their signatures. This uncertainty mainly originates from the patchy coverage of SDSS in the south Galactic cap, and this situation will be improved by future wide-field spectroscopic surveys.

A family of compact high order coupled time-space unconditionally stable vertical advection schemes

NASA Astrophysics Data System (ADS)

Lemarié, Florian; Debreu, Laurent

2016-04-01

Recent papers by Shchepetkin (2015) and Lemarié et al. (2015) have emphasized that the time-step of an oceanic model with an Eulerian vertical coordinate and an explicit time-stepping scheme is very often restricted by vertical advection in a few hot spots (i.e. most of the grid points are integrated with small Courant numbers, compared to the Courant-Friedrichs-Lewy (CFL) condition, except just few spots where numerical instability of the explicit scheme occurs first). The consequence is that the numerics for vertical advection must have good stability properties while being robust to changes in Courant number in terms of accuracy. An other constraint for oceanic models is the strict control of numerical mixing imposed by the highly adiabatic nature of the oceanic interior (i.e. mixing must be very small in the vertical direction below the boundary layer). We examine in this talk the possibility of mitigating vertical Courant-Friedrichs-Lewy (CFL) restriction, while avoiding numerical inaccuracies associated with standard implicit advection schemes (i.e. large sensitivity of the solution on Courant number, large phase delay, and possibly excess of numerical damping with unphysical orientation). Most regional oceanic models have been successfully using fourth order compact schemes for vertical advection. In this talk we present a new general framework to derive generic expressions for (one-step) coupled time and space high order compact schemes (see Daru & Tenaud (2004) for a thorough description of coupled time and space schemes). Among other properties, we show that those schemes are unconditionally stable and have very good accuracy properties even for large Courant numbers while having a very reasonable computational cost.

Study on a New Combination Method and High Efficiency Outer Rotor Type Permanent Magnet Motors

NASA Astrophysics Data System (ADS)

Enomoto, Yuji; Kitamura, Masashi; Motegi, Yasuaki; Andoh, Takashi; Ochiai, Makoto; Abukawa, Toshimi

The segment stator core, high space factor coil, and high efficiency magnet are indispensable technologies in the development of compact and a high efficiency motors. But adoption of the segment stator core and high space factor coil has not progressed in the field of outer rotor type motors, for the reason that the inner components cannot be laser welded together. Therefore, we have examined a segment stator core combination technology for the purposes of getting a large increase in efficiency and realizing miniaturization. We have also developed a characteristic estimation method which provides the most suitable performance for segment stator core motors.

Spacecraft Applications of Compact Optical and Mass Spectrometers

NASA Technical Reports Server (NTRS)

Davinic, N. M.; Nagel, D. J.

1995-01-01

Optical spectrometers, and mass spectrometers to a lesser extent, have a long and rich history of use aboard spacecraft. Space mission applications include deep space science spacecraft, earth orbiting satellites, atmospheric probes, and surface landers, rovers, and penetrators. The large size of capable instruments limited their use to large, expensive spacecraft. Because of the novel application of micro-fabrication technologies, compact optical and mass spectrometers are now available. The new compact devices are especially attractive for spacecraft because of their small mass and volume, as well as their low power consumption. Dispersive optical multi-channel analyzers which cover the 0.4-1.1 micrometer wavelength are now commercially available in packages as small as 3 x 6 x 18 mm exclusive of drive and recording electronics. Mass spectrometers as small as 3 x 3 mm, again without electronics, are under development. A variety of compact optical and mass spectrometers are reviewed in this paper. A number of past space applications are described, along with some upcoming opportunities that are likely candidate missions to fly this new class of compact spectrometers.

Geospatial methods provide timely and comprehensive urban forest information

Treesearch

Kathleen T. Ward; Gary R. Johnson

2007-01-01

Urban forests are unique and highly valued resources. However, trees in urban forests are often under greater stress than those in rural or undeveloped areas due to soil compaction, restricted growing spaces, high temperatures, and exposure to air and water pollution. In addition, conditions change more quickly in urban as opposed to rural and undeveloped settings....

Strategy Guideline. Compact Air Distribution Systems

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

Burdick, Arlan

2013-06-01

This guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balancedmore » HVAC system, and overall improved energy efficiency of the home.« less

Geodetic glacier mass balancing on ice caps - inseparably connected to firn modelling?

NASA Astrophysics Data System (ADS)

Saß, Björn L.; Sauter, Tobias; Seehaus, Thorsten; Braun, Matthias H.

2017-04-01

Observed melting of glaciers and ice caps in the polar regions contribute to the ongoing global sea level rise (SLR). A rising sea level and its consequences are one of the major challenges for coastal societies in the next decades to centuries. Gaining knowledge about the main drivers of SLR and bringing it together is one recent key-challenge for environmental science. The high arctic Svalbard archipelago faced a strong climatic change in the last decades, associated with a change in the cryosphere. Vestfonna, a major Arctic ice cap in the north east of Svalbard, harbors land and marine terminating glaciers, which expose a variability of behavior. We use high resolution remote sensing data from space-borne radar (TanDEM-X, TerraSAR-X, Sentinel-1a), acquired between 2009 and 2015, to estimate glacier velocity and high accurate surface elevation changes. For DEM registration we use space-borne laser altimetry (ICESat) and an existing in-situ data archive (IPY Kinnvika). In order to separate individual glacier basin changes for a detailed mass balance study and for further SLR contribution estimates, we use glacier outlines from the Global Land Ice Measurements from Space (GLIMS) project. Remaining challenges of space-borne observations are the reduction of measurement uncertainties, in the case of Synthetic Aperture Radar most notably signal penetration into the glacier surface. Furthermore, in order to convert volume to mass change one has to use the density of the changed mass (conversion factor) and one has to account for the mass conservation processes in the firn package (firn compaction). Both, the conversion factor and the firn compaction are not (yet) measurable for extensive ice bodies. They have to be modelled by coupling point measurements and regional gridded climate data. Results indicate a slight interior thickening contrasted with wide spread thinning in the ablation zone of the marine terminating outlets. While one glacier system draining to the north west shows re-advance and possibly surge evidence, the majority of the outlets draining south- and eastwards are in stable or retreating dynamic conditions. Only two southern outlet glaciers speeded up between 2009 and 2015. We target measurement uncertainties by using in-situ missions as well as further comparable space-borne sensors. The mass conversion factor ('dhdt-problem') and the compaction processes are estimated by an pythonic offline firn compaction model (FCM) which is forced with Regional Climate Model (RCM) data. The RCM data and the FCM output are validated against an in-situ data archive.

Hubble Space Telescope observations of the optical counterpart to a ultra-compact high-velocity cloud

NASA Astrophysics Data System (ADS)

Sand, David J.

2017-01-01

As part of a comprehensive archival search for optical counterparts to ultra-compact high-velocity clouds (UCHVCs), our team has uncovered five Local Volume dwarf galaxies, two of which were not previously known. Among these was AGC 226067, also known as ALFALFA-Dw1, which appeared to be made up of several HI and blue optical clumps based on ground-based data, with at least one HII region. Here we present Hubble Space Telescope Advanced Camera for Surveys data of AGC 226067. The data show that AGC 226067 is made up of a ~7-30 Myr old stellar population with a [Fe/H]~-0.6. Further, there is no evidence for an old stellar population associated with the system, down to a limit of MV>-8. Based on this and the position of AGC 226067 in the outskirts of the M86 subgroup of the Virgo cluster we present various arguments for the origin of this strange stellar system.

ROSA Transfer (for SpaceX CRS-11)

NASA Image and Video Library

2017-04-12

Outside the Space Station Processing Facility high bay at NASA's Kennedy Space Center in Florida, a technician uses a Hyster forklift to carry the Roll-Out Solar Array, or ROSA, to the loading dock. ROSA will be delivered to the International Space Station aboard the SpaceX Dragon cargo carrier on the company’s 11th commercial resupply services mission to the space station. ROSA is a new type of solar panel that rolls open in space and is more compact than current rigid panel designs. The ROSA investigation will test deployment and retraction, shape changes when the Earth blocks the sun, and other physical challenges to determine the array's strength and durability.

ROSA Transfer (for SpaceX CRS-11)

NASA Image and Video Library

2017-04-12

At the loading dock outside the Space Station Processing Facility high bay at NASA's Kennedy Space Center in Florida, a technician uses a Hyster forklift to load the Roll-Out Solar Array, or ROSA, into a truck. ROSA will be delivered to the International Space Station aboard the SpaceX Dragon cargo carrier on the company’s 11th commercial resupply services mission to the space station. ROSA is a new type of solar panel that rolls open in space and is more compact than current rigid panel designs. The ROSA investigation will test deployment and retraction, shape changes when the Earth blocks the sun, and other physical challenges to determine the array's strength and durability.

Design and Operational Characteristics of the Shuttle Coherent Wind Lidar

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Spiers, Gary D.; Peters, Bruce R.; Li, Ye; Blackwell, Timothy S.; Geary, Joseph M.

1998-01-01

NOAA has identified the measurement of atmospheric wind velocities as one of the key unmet data sets for its next generation of sensing platforms. The merits of coherent lidars for the measurement of atmospheric winds from space platforms have been widely recognized; however, it is only recently that several key technologies have advanced to a point where a compact, high fidelity system could be created. Advances have been made in the areas of the diode-pumped, eye-safe, solid state lasers and room temperature, wide bandwidth, semiconductor detectors operating in the near-infrared region. These new lasers can be integrated into efficient and compact optical systems creating new possibilities for the development of low-cost, reliable, and compact coherent lidar systems for wind measurements. Over the past five years, the University of Alabama in Huntsville (UAH) has been working toward further advancing the solid state coherent lidar technology for the measurement of atmospheric winds from space. As part of this effort, UAH had established the design characteristics and defined the expected performance for three different proposed space-based instruments: a technology demonstrator, an operational prototype, and a 7-year lifetime operational instrument. SPARCLE is an ambitious project that is intended to evaluate the suitability of coherent lidar for wind measurements, demonstrate the maturity of the technology for space application, and provide a useable data set for model development and validation. This paper describes the SPARCLE instrument's major physical and environmental design constraints, optical and mechanical designs, and its operational characteristics.

Constraining the physical state by symmetries

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

Fatibene, L., E-mail: lorenzo.fatibene@unito.it; INFN - Sezione Torino - IS QGSKY; Ferraris, M.

After reviewing the hole argument and its relations with initial value problem and general covariance, we shall discuss how much freedom one has to define the physical state in a generally covariant field theory (with or without internal gauge symmetries). Our analysis relies on Cauchy problems, thus it is restricted to globally hyperbolic spacetimes. We shall show that in generally covariant theories on a compact space (as well as for internal gauge symmetries on any spacetime) one has no freedom and one is forced to declare as physically equivalent two configurations which differ by a global spacetime diffeomorphism (or bymore » an internal gauge transformation) as it is usually prescribed. On the contrary, when space is not compact, the result does not hold true and one may have different options to define physically equivalent configurations, still preserving determinism. - Highlights: • Investigate the relation between the hole argument, covariance, determinism and physical state. • Show that if space is compact then any diffeomorphism is a gauge symmetry. • Show that if space is not compact then there may be more freedom in choosing gauge group.« less

Gas-cell atomic clocks for space: new results and alternative schemes

NASA Astrophysics Data System (ADS)

Affolderbach, C.; Breschi, E.; Schori, C.; Mileti, G.

2017-11-01

We present our development activities on compact Rubidium gas-cell atomic frequency standards, for use in space-borne and ground-based applications. We experimentally demonstrate a high-performance laser optically-pumped Rb clock for space applications such as telecommunications, science missions, and satellite navigation systems (e.g. GALILEO). Using a stabilised laser source and optimized gas cells, we reach clock stabilities as low as 1.5·10-12 τ-1/2 up to 103 s and 4·10-14 at 104 s. The results demonstrate the feasibility of a laser-pumped Rb clock reaching < 1·10-12 τ-1/2 in a compact device (<2 liters, 2 kg, 20 W), given optimization of the implemented techniques. A second activity concerns more radically miniaturized gas-cell clocks, aiming for low power consumption and a total volume around 1 cm3 , at the expense of relaxed frequency stability. Here miniaturized "chip-scale" vapour cells and use of coherent laser interrogation techniques are at the heart of the investigations.

The space optical clocks project

NASA Astrophysics Data System (ADS)

Schiller, S.; Tino, G. M.; Lemonde, P.; Sterr, U.; Lisdat, Ch.; Görlitz, A.; Poli, N.; Nevsky, A.; Salomon, C.

2017-11-01

The Space Optical Clocks project aims at operating lattice clocks on the ISS for tests of fundamental physics and for providing high-accuracy comparisons of future terrestrial optical clocks. A pre-phase-A study (2007- 10), funded partially by ESA and DLR, included the implementation of several optical lattice clock systems using Strontium and Ytterbium as atomic species and their characterization. Subcomponents of clock demonstrators with the added specification of transportability and using techniques suitable for later space use, such as all-solid-state lasers, low power consumption, and compact dimensions, have been developed and have been validated. This included demonstration of laser-cooling and magneto-optical trapping of Sr atoms in a compact breadboard apparatus and demonstration of a transportable clock laser with 1 Hz linewidth. With two laboratory Sr lattice clock systems a number of fundamental results were obtained, such as observing atomic resonances with linewidths as low as 3 Hz, non-destructive detection of atom excitation, determination of decoherence effects and reaching a frequency instability of 1×10-16.

A study of radar cross section measurement techniques

NASA Technical Reports Server (NTRS)

Mcdonald, Malcolm W.

1986-01-01

Past, present, and proposed future technologies for the measurement of radar cross section were studied. The purpose was to determine which method(s) could most advantageously be implemented in the large microwave anechoic chamber facility which is operated at the antenna test range site. The progression toward performing radar cross section measurements of space vehicles with which the Orbital Maneuvering Vehicle will be called upon to rendezvous and dock is a natural outgrowth of previous work conducted in recent years of developing a high accuracy range and velocity sensing radar system. The radar system was designed to support the rendezvous and docking of the Orbital Maneuvering Vehicle with various other space vehicles. The measurement of radar cross sections of space vehicles will be necessary in order to plan properly for Orbital Maneuvering Vehicle rendezvous and docking assignments. The methods which were studied include: standard far-field measurements; reflector-type compact range measurements; lens-type compact range measurement; near field/far field transformations; and computer predictive modeling. The feasibility of each approach is examined.

Open strings and electric fields in compact spaces

NASA Astrophysics Data System (ADS)

Condeescu, Cezar; Dudas, Emilian; Pradisi, Gianfranco

2018-05-01

We analyse open strings with background electric fields in the internal space, T-dual to branes moving with constant velocities in the internal space. We find that the direction of the electric fields inside a two torus, dual to the D-brane velocities, has to be quantised such that the corresponding direction is compact. This implies that D-brane motion in the internal torus is periodic, with a periodicity that can be parametrically large in terms of the internal radii. By S-duality, this is mapped into an internal magnetic field in a three torus, a quantum mechanical analysis of which yields a similar result, i.e. the parallel direction to the magnetic field has to be compact. Furthermore, for the magnetic case, we find the Landau level degeneracy as being given by the greatest common divisor of the flux numbers. We carry on the string quantisation and derive the relevant partition functions for these models. Our analysis includes also the case of oblique electric fields which can arise when several stacks of branes are present. Compact dimensions and/or oblique sectors influence the energy loss of the system through pair-creation and thus can be relevant for inflationary scenarios with branes. Finally, we show that the compact energy loss is always larger than the non-compact one.

On spectral synthesis on element-wise compact Abelian groups

NASA Astrophysics Data System (ADS)

Platonov, S. S.

2015-08-01

Let G be an arbitrary locally compact Abelian group and let C(G) be the space of all continuous complex-valued functions on G. A closed linear subspace \\mathscr H\\subseteq C(G) is referred to as an invariant subspace if it is invariant with respect to the shifts τ_y\\colon f(x)\\mapsto f(xy), y\\in G. By definition, an invariant subspace \\mathscr H\\subseteq C(G) admits strict spectral synthesis if \\mathscr H coincides with the closure in C(G) of the linear span of all characters of G belonging to \\mathscr H. We say that strict spectral synthesis holds in the space C(G) on G if every invariant subspace \\mathscr H\\subseteq C(G) admits strict spectral synthesis. An element x of a topological group G is said to be compact if x is contained in some compact subgroup of G. A group G is said to be element-wise compact if all elements of G are compact. The main result of the paper is the proof of the fact that strict spectral synthesis holds in C(G) for a locally compact Abelian group G if and only if G is element-wise compact. Bibliography: 14 titles.

Movable-molybdenum-reflector reactivity experiments for control studies of compact space power reactor concepts

NASA Technical Reports Server (NTRS)

Fox, T. A.

1973-01-01

An experimental reflector reactivity study was made with a compact cylindrical reactor using a uranyl fluoride - water fuel solution. The reactor was axially unreflected and radially reflected with segments of molybdenum. The reflector segments were displaced incrementally in both the axial and radial dimensions, and the shutdown of each configuration was measured by using the pulsed-neutron source technique. The reactivity effects for axial and radial displacement of reflector segments are tabulated separately and compared. The experiments provide data for control-system studies of compact-space-power-reactor concepts.

Extending Your Reach.

ERIC Educational Resources Information Center

Batterman, Christopher T.

2002-01-01

High-density mobile storage (storage units mounted on carriages and rails which move and compact to utilize wasted space) can double the capacity of an existing school library facility. This article describes the benefits of going mobile and looks at the advantages of powered, programmable mobile storage systems. A sidebar describes Michigan…

Curved noncommutative tori as Leibniz quantum compact metric spaces

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

Latrémolière, Frédéric, E-mail: frederic@math.du.edu

We prove that curved noncommutative tori are Leibniz quantum compact metric spaces and that they form a continuous family over the group of invertible matrices with entries in the image of the quantum tori for the conjugation by modular conjugation operator in the regular representation, when this group is endowed with a natural length function.

ROSA deploy

NASA Image and Video Library

2017-06-18

iss052e002857 (6/18/2017) --- The Roll-Out Solar Array (ROSA) is a new type of solar panel that rolls open in space like a party favor and is more compact than current rigid panel designs. The ROSA investigation tests deployment and retraction, shape changes when the Earth blocks the sun, and other physical challenges to determine the array’s strength and durability. ROSA has the potential to replace solar arrays on future satellites, making them more compact and lighter weight. Satellite radio and television, weather forecasting, GPS and other services used on Earth would all benefit from high-performance solar arrays.

ROSA deploy

NASA Image and Video Library

2017-06-18

iss052e004379 (6/18/2017) --- The Roll-Out Solar Array (ROSA) is a new type of solar panel that rolls open in space like a party favor and is more compact than current rigid panel designs. The ROSA investigation tests deployment and retraction, shape changes when the Earth blocks the sun, and other physical challenges to determine the array’s strength and durability. ROSA has the potential to replace solar arrays on future satellites, making them more compact and lighter weight. Satellite radio and television, weather forecasting, GPS and other services used on Earth would all benefit from high-performance solar arrays.

ROSA deploy

NASA Image and Video Library

2017-06-18

iss052e002871 (6/18/2017) --- The Roll-Out Solar Array (ROSA) is a new type of solar panel that rolls open in space like a party favor and is more compact than current rigid panel designs. The ROSA investigation tests deployment and retraction, shape changes when the Earth blocks the sun, and other physical challenges to determine the array’s strength and durability. ROSA has the potential to replace solar arrays on future satellites, making them more compact and lighter weight. Satellite radio and television, weather forecasting, GPS and other services used on Earth would all benefit from high-performance solar arrays.

NAOMI instrument: a product line of compact and versatile cameras designed for high resolution missions in Earth observation

NASA Astrophysics Data System (ADS)

Luquet, Ph.; Chikouche, A.; Benbouzid, A. B.; Arnoux, J. J.; Chinal, E.; Massol, C.; Rouchit, P.; De Zotti, S.

2017-11-01

EADS Astrium is currently developing a new product line of compact and versatile instruments for high resolution missions in Earth Observation. First version has been developed in the frame of the ALSAT-2 contract awarded by the Algerian Space Agency (ASAL) to EADS Astrium. The Silicon Carbide Korsch-type telescope coupled with a multilines detector array offers a 2.5 m GSD in PAN band at Nadir @ 680 km altitude (10 m GSD in the four multispectral bands) with a 17.5 km swath width. This compact camera - 340 (W) x 460 (L) x 510 (H) mm3, 13 kg - is embarked on a Myriade-type small platform. The electronics unit accommodates video, housekeeping, and thermal control functions and also a 64 Gbit mass memory. Two satellites are developed; the first one is planned to be launched on mid 2009. Several other versions of the instrument have already been defined with enhanced resolution or/and larger field of view.

Compact and broadband antenna based on a step-shaped metasurface.

PubMed

Li, Ximing; Yang, Jingjing; Feng, Yun; Yang, Meixia; Huang, Ming

2017-08-07

A metasurface (MS) is highly useful for improving the performance of patch antennae and reducing their size due to their inherent and unique electromagnetic properties. In this paper, a compact and broadband antenna based on a step-shaped metasurface (SMS) at an operating frequency of 4.3 GHz is presented, which is fed by a planar monopole and enabled by selecting an SMS with high selectivity. The SMS consists of an array of metallic step-shaped unit cells underneath the monopole, which provide footprint miniaturization and bandwidth expansion. Numerical results show that the SMS-based antenna with a maximum size of 0.42λ02 (where λ 0 is the operating wavelength in free space) exhibits a 22.3% impedance bandwidth (S11 < -10 dB) and a high gain of more than 7.15 dBi within the passband. Experimental results at microwave frequencies verify the performance of the proposed antenna, demonstrating substantial consistency with the simulation results. The compact and broadband antenna therefore predicts numerous potential applications within modern wireless communication systems.

Optimal space of linear classical observables for Maxwell k-forms via spacelike and timelike compact de Rham cohomologies

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

Benini, Marco, E-mail: mbenini87@gmail.com, E-mail: mbenini@uni-potsdam.de

Being motivated by open questions in gauge field theories, we consider non-standard de Rham cohomology groups for timelike compact and spacelike compact support systems. These cohomology groups are shown to be isomorphic respectively to the usual de Rham cohomology of a spacelike Cauchy surface and its counterpart with compact support. Furthermore, an analog of the usual Poincaré duality for de Rham cohomology is shown to hold for the case with non-standard supports as well. We apply these results to find optimal spaces of linear observables for analogs of arbitrary degree k of both the vector potential and the Faraday tensor.more » The term optimal has to be intended in the following sense: The spaces of linear observables we consider distinguish between different configurations; in addition to that, there are no redundant observables. This last point in particular heavily relies on the analog of Poincaré duality for the new cohomology groups.« less

Compact field color schlieren system for use in microgravity materials processing

NASA Technical Reports Server (NTRS)

Poteet, W. M.; Owen, R. B.

1986-01-01

A compact color schlieren system designed for field measurement of materials processing parameters has been built and tested in a microgravity environment. Improvements in the color filter design and a compact optical arrangement allowed the system described here to retain the traditional advantages of schlieren, such as simplicity, sensitivity, and ease of data interpretation. Testing was accomplished by successfully flying the instrument on a series of parabolic trajectories on the NASA KC-135 microgravity simulation aircraft. A variety of samples of interest in materials processing were examined. Although the present system was designed for aircraft use, the technique is well suited to space flight experimentation. A major goal of this effort was to accommodate the main optical system within a volume approximately equal to that of a Space Shuttle middeck locker. Future plans include the development of an automated space-qualified facility for use on the Shuttle and Space Station.

Quantum Communication with a High-Rate Entangled Photon Source

NASA Technical Reports Server (NTRS)

Wilson, Nathaniel C.; Chaffee, Dalton W.; Lekki, John D.; Wilson, Jeffrey D.

2016-01-01

A high generation rate photon-pair source using a dual element periodically-poled potassium titanyl phosphate (PP KTP) waveguide is described. The photon-pair source features a high pair generation rate, a compact power-efficient package, and continuous wave (CW) or pulsed operation. Characterization and test results are presented. Details and preliminary results of a laboratory free-space QKD experiment with the B92 protocol are also presented.

A semiconductor radiation imaging pixel detector for space radiation dosimetry

NASA Astrophysics Data System (ADS)

Kroupa, Martin; Bahadori, Amir; Campbell-Ricketts, Thomas; Empl, Anton; Hoang, Son Minh; Idarraga-Munoz, John; Rios, Ryan; Semones, Edward; Stoffle, Nicholas; Tlustos, Lukas; Turecek, Daniel; Pinsky, Lawrence

2015-07-01

Progress in the development of high-performance semiconductor radiation imaging pixel detectors based on technologies developed for use in high-energy physics applications has enabled the development of a completely new generation of compact low-power active dosimeters and area monitors for use in space radiation environments. Such detectors can provide real-time information concerning radiation exposure, along with detailed analysis of the individual particles incident on the active medium. Recent results from the deployment of detectors based on the Timepix from the CERN-based Medipix2 Collaboration on the International Space Station (ISS) are reviewed, along with a glimpse of developments to come. Preliminary results from Orion MPCV Exploration Flight Test 1 are also presented.

Pilot Kent Rominger compacts trash container

NASA Image and Video Library

1995-11-05

STS073-356-018 (20 October - 5 November 1995) --- Astronaut Kent V. Rominger, pilot, demonstrates an age-old trash-compacting method on the middeck of the Earth-orbiting Space Shuttle Columbia. Following a meal, Rominger had collected the residue wrappers, etc. and filled a plastic bag. Following his compacting maneuvers, Rominger went on to deposit the sack into a temporary trash-stowage area beneath the middeck. Making his first flight into space, Rominger joined four other NASA astronauts and two guest researchers for more than two weeks' research in support of the United States Microgravity Laboratory (USML-2) mission.

Pipe support

DOEpatents

Pollono, Louis P.

1979-01-01

A pipe support for high temperature, thin-walled piping runs such as those used in nuclear systems. A section of the pipe to be supported is encircled by a tubular inner member comprised of two walls with an annular space therebetween. Compacted load-bearing thermal insulation is encapsulated within the annular space, and the inner member is clamped to the pipe by a constant clamping force split-ring clamp. The clamp may be connected to pipe hangers which provide desired support for the pipe.

Development of compact particle detectors for space based instruments

NASA Astrophysics Data System (ADS)

Barner, Lindsey; Grove, Andrew; Mohler, Jacob; Sisson, Caleb; Roth, Alex; Kryemadhi, Abaz

2017-01-01

The Silicon Photomultipliers (SiPMs) are new photon-detectors which have been increasingly used in particle physics. Their small size, good single photon resolution, simple readout, and immunity to magnetic fields offers benefits compared to traditional photomultipliers. LYSO and CeBr3 crystals are relatively new scintillators with high stopping power, very good light yield and fast decay time. The response of these detectors to low energy gamma rays will be presented. NASA Pennsylvania Space Grant Consortium.

Global Bifurcation of Periodic Solutions with Symmetry,

DTIC Science & Technology

1987-07-01

C4-family of sectorial operators on a real Hilbert (2.32.a) space X, with dense domain D(A(A)) which is independent of A E E, and with compact...Vanl, theorem 2.5.91. If .F and E’ are both Hilbert spaces with orthogonal action of r, we may drop the assumption that 1 is compact. Just take...some meandering. Let us define a limit for any sequence Si of subsets of some metric space . Following Whyburn [Why], we define lir sup Si {z: z

SpaceCube Version 1.5

NASA Technical Reports Server (NTRS)

Geist, Alessandro; Lin, Michael; Flatley, Tom; Petrick, David

2013-01-01

SpaceCube 1.5 is a high-performance and low-power system in a compact form factor. It is a hybrid processing system consisting of CPU (central processing unit), FPGA (field-programmable gate array), and DSP (digital signal processor) processing elements. The primary processing engine is the Virtex- 5 FX100T FPGA, which has two embedded processors. The SpaceCube 1.5 System was a bridge to the SpaceCube 2.0 and SpaceCube 2.0 Mini processing systems. The SpaceCube 1.5 system was the primary avionics in the successful SMART (Small Rocket/Spacecraft Technology) Sounding Rocket mission that was launched in the summer of 2011. For SMART and similar missions, an avionics processor is required that is reconfigurable, has high processing capability, has multi-gigabit interfaces, is low power, and comes in a rugged/compact form factor. The original SpaceCube 1.0 met a number of the criteria, but did not possess the multi-gigabit interfaces that were required and is a higher-cost system. The SpaceCube 1.5 was designed with those mission requirements in mind. The SpaceCube 1.5 features one Xilinx Virtex-5 FX100T FPGA and has excellent size, weight, and power characteristics [4×4×3 in. (approx. = 10×10×8 cm), 3 lb (approx. = 1.4 kg), and 5 to 15 W depending on the application]. The estimated computing power of the two PowerPC 440s in the Virtex-5 FPGA is 1100 DMIPS each. The SpaceCube 1.5 includes two Gigabit Ethernet (1 Gbps) interfaces as well as two SATA-I/II interfaces (1.5 to 3.0 Gbps) for recording to data drives. The SpaceCube 1.5 also features DDR2 SDRAM (double data rate synchronous dynamic random access memory); 4- Gbit Flash for storing application code for the CPU, FPGA, and DSP processing elements; and a Xilinx Platform Flash XL to store FPGA configuration files or application code. The system also incorporates a 12 bit analog to digital converter with the ability to read 32 discrete analog sensor inputs. The SpaceCube 1.5 design also has a built-in accelerometer. In addition, the system has 12 receive and transmit RS- 422 interfaces for legacy support. The SpaceCube 1.5 processor card represents the first NASA Goddard design in a compact form factor featuring the Xilinx Virtex- 5. The SpaceCube 1.5 incorporates backward compatibility with the Space- Cube 1.0 form factor and stackable architecture. It also makes use of low-cost commercial parts, but is designed for operation in harsh environments.

A heterodyne interferometer for high resolution translation and tilt measurement as optical readout for the LISA inertial sensor

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Kraus, Hans-Jürgen; Weise, Dennis; Braxmaier, Claus; Peters, Achim; Johann, Ulrich

2017-11-01

The space-based gravitational wave detector LISA (Laser Interferometer Space Antenna) requires a high performance position sensor in order to measure the translation and tilt of the free flying test mass with respect to the LISA optical bench. Here, we present a mechanically highly stable and compact setup of a heterodyne interferometer combined with differential wavefront sensing for the tilt measurement which serves as a demonstrator for an optical readout of the LISA test mass position. First results show noise levels below 1 nm/√Hz and 1 μrad/√Hz, respectively, for frequencies < 10-3 Hz.

Progress in space nuclear reactor power systems technology development - The SP-100 program

NASA Technical Reports Server (NTRS)

Davis, H. S.

1984-01-01

Activities related to the development of high-temperature compact nuclear reactors for space applications had reached a comparatively high level in the U.S. during the mid-1950s and 1960s, although only one U.S. nuclear reactor-powered spacecraft was actually launched. After 1973, very little effort was devoted to space nuclear reactor and propulsion systems. In February 1983, significant activities toward the development of the technology for space nuclear reactor power systems were resumed with the SP-100 Program. Specific SP-100 Program objectives are partly related to the determination of the potential performance limits for space nuclear power systems in 100-kWe and 1- to 100-MW electrical classes. Attention is given to potential missions and applications, regimes of possible space power applicability, safety considerations, conceptual system designs, the establishment of technical feasibility, nuclear technology, materials technology, and prospects for the future.

Cross-indexing of binary SIFT codes for large-scale image search.

PubMed

Liu, Zhen; Li, Houqiang; Zhang, Liyan; Zhou, Wengang; Tian, Qi

2014-05-01

In recent years, there has been growing interest in mapping visual features into compact binary codes for applications on large-scale image collections. Encoding high-dimensional data as compact binary codes reduces the memory cost for storage. Besides, it benefits the computational efficiency since the computation of similarity can be efficiently measured by Hamming distance. In this paper, we propose a novel flexible scale invariant feature transform (SIFT) binarization (FSB) algorithm for large-scale image search. The FSB algorithm explores the magnitude patterns of SIFT descriptor. It is unsupervised and the generated binary codes are demonstrated to be dispreserving. Besides, we propose a new searching strategy to find target features based on the cross-indexing in the binary SIFT space and original SIFT space. We evaluate our approach on two publicly released data sets. The experiments on large-scale partial duplicate image retrieval system demonstrate the effectiveness and efficiency of the proposed algorithm.

Hubble space telescope observations and geometric models of compact multipolar planetary nebulae

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

Hsia, Chih-Hao; Chau, Wayne; Zhang, Yong

2014-05-20

We report high angular resolution Hubble Space Telescope observations of 10 compact planetary nebulae (PNs). Many interesting internal structures, including multipolar lobes, arcs, two-dimensional rings, tori, and halos, are revealed for the first time. These results suggest that multipolar structures are common among PNs, and these structures develop early in their evolution. From three-dimensional geometric models, we have determined the intrinsic dimensions of the lobes. Assuming the lobes are the result of interactions between later-developed fast winds and previously ejected asymptotic giant branch winds, the geometric structures of these PNs suggest that there are multiple phases of fast winds separatedmore » by temporal variations and/or directional changes. A scenario of evolution from lobe-dominated to cavity-dominated stages is presented. The results reported here will provide serious constraints on any dynamical models of PNs.« less

Free-space laser communication technologies II; Proceedings of the Meeting, Los Angeles, CA, Jan. 15-17, 1990

NASA Technical Reports Server (NTRS)

Begley, David L. (Editor); Seery, Bernard D. (Editor)

1990-01-01

Various papers on free-space laser communication technologies are presented. Individual topics addressed include: optical intersatellite link experiment between the earth station and ETS-VI, the Goddard optical communications program, technologies and techniques for lasercom terminal size, weight, and cost reduction, laser beam acquisition and tracking system for ETS-VI laser communication equipment, analog dividers for acquisition and tracking signal normalization, fine pointing mechanism using multilayered piezoelectric actuator for optical ISL system, analysis of SILEX tracking sensor performance, new telescope concept for space communication, telescope considered as a very high gain antenna, design of compact transceiver optical systems for optical intersatellite links, ultralightweight optics for laser communications, highly sensitive measurement method for stray light and retroreflected light, depolarization effects on free space laser transceiver communication systems, in-orbit measurements of microaccelerations of ESA's communication satellite Olympus, high-performance laser diode transmitter for optical free space communication, diode-pumped Nd:host laser transmitter for intersatellite optical communications, single-frequency diode-pumped laser for free-space communication.

A semiconductor radiation imaging pixel detector for space radiation dosimetry.

PubMed

Kroupa, Martin; Bahadori, Amir; Campbell-Ricketts, Thomas; Empl, Anton; Hoang, Son Minh; Idarraga-Munoz, John; Rios, Ryan; Semones, Edward; Stoffle, Nicholas; Tlustos, Lukas; Turecek, Daniel; Pinsky, Lawrence

2015-07-01

Progress in the development of high-performance semiconductor radiation imaging pixel detectors based on technologies developed for use in high-energy physics applications has enabled the development of a completely new generation of compact low-power active dosimeters and area monitors for use in space radiation environments. Such detectors can provide real-time information concerning radiation exposure, along with detailed analysis of the individual particles incident on the active medium. Recent results from the deployment of detectors based on the Timepix from the CERN-based Medipix2 Collaboration on the International Space Station (ISS) are reviewed, along with a glimpse of developments to come. Preliminary results from Orion MPCV Exploration Flight Test 1 are also presented. Copyright © 2015 The Committee on Space Research (COSPAR). All rights reserved.

The Development of a Simulator System and Hardware Test Bed for Deep Space X-Ray Navigation

NASA Astrophysics Data System (ADS)

Doyle, Patrick T.

2013-03-01

Currently, there is a considerable interest in developing technologies that will allow using photon measurements from celestial x-ray sources for deep space navigation. The impetus for this is that many envisioned future space missions will require spacecraft to have autonomous navigation capabilities. For missions close to Earth, Global Navigation Satellite Systems (GNSS) such as GPS are readily available for use, but for missions far from Earth, other alternatives must be provided. While existing systems such as the Deep Space Network (DSN) can be used, latencies associated with servicing a fleet of vehicles may not be compatible with some autonomous operations requiring timely updates of their navigation solution. Because of their somewhat predictable emissions, pulsars are the ideal candidates for x-ray sources that can be used to provide key parameters for navigation. Algorithms and simulation tools that will enable designing and analyzing x-ray navigation concepts are presented. The development of a compact x-ray detector system is pivotal to the eventual deployment of such navigation systems. Therefore, results of a high altitude balloon test to evaluate the design of a compact x-ray detector system are described as well.

Cryogenic Cooling for Myriad Applications-A STAR Is Born

NASA Technical Reports Server (NTRS)

2006-01-01

Cryogenics, the science of generating extremely low temperatures, has wide applicability throughout NASA. The Agency employs cryogenics for rocket propulsion, high-pressure gas supply, breathable air in space, life support equipment, electricity, water, food preservation and packaging, medicine, imaging devices, and electronics. Cryogenic liquid oxygen and liquid hydrogen systems are also replacing solid rocket motor propulsion systems in most of the proposed launch systems, a reversion to old-style liquid propellants. In the late 1980s, NASA wanted a compact linear alternator/motor with reduced size and mass, as well as high efficiency, that had unlimited service life for use in a thermally driven power generator for space power applications. Prior development work with free-piston Stirling converters (a Stirling engine integrated with a linear actuator that produces electrical power output) had shown the promise of that technology for high-power space applications. A dual use for terrestrial applications exists for compact Stirling converters for onsite combined heat and power units. The Stirling cycle is also usable in reverse as a refrigeration cycle suitable for cryogenic cooling, so this Stirling converter work promised double benefits as well as dual uses. The uses for cryogenic coolers within NASA abound; commercial applications are similarly wide-ranging, from cooling liquid oxygen and nitrogen, to cryobiology and bio-storage, cryosurgery, instrument and detector cooling, semiconductor manufacturing, and support service for cooled superconducting power systems.

Millimeter-Wave Wireless Power Transfer Technology for Space Applications

NASA Technical Reports Server (NTRS)

Chattopadhyay, Goutam; Manohara, Harish; Mojarradi, Mohammad M.; Vo, Tuan A.; Mojarradi, Hadi; Bae, Sam Y.; Marzwell, Neville

2008-01-01

In this paper we present a new compact, scalable, and low cost technology for efficient receiving of power using RF waves at 94 GHz. This technology employs a highly innovative array of slot antennas that is integrated on substrate composed of gold (Au), silicon (Si), and silicon dioxide (SiO2) layers. The length of the slots and spacing between them are optimized for a highly efficient beam through a 3-D electromagnetic simulation process. Antenna simulation results shows a good beam profile with very low side lobe levels and better than 93% antenna efficiency.

Lockheed Martin microcryocoolers

NASA Astrophysics Data System (ADS)

Olson, Jeffrey R.; Roth, Eric W.; Sanders, Lincoln-Shaun; Will, Eric; Frank, David J.

2017-05-01

Lockheed Martin's Advanced Technology Center, part of Lockheed Martin Space Systems Company, has developed a series of long life microcryocoolers for avionics and space sensor applications. We report the development and testing of three varieties of single-stage, compact, coaxial, pulse tube microcryocoolers. These coolers support emerging large, high operating temperature (100-150K) infrared focal plane array sensors with nominal cooling loads of 200-2000 mW, and all share long life technology attributes used in space cryocoolers, which typically provide 10 years of continuous operation on orbit without degradation. These three models of microcryocooler are the 345 gram Micro1-1, designed to provide 1 W cooling at 150 K, the 450 gram Micro1-2, designed to provide 2 W cooling at 105 K, and the 320 gram Micro1-3, designed to provide 300 mW cooling at 125 K while providing the capability to cool the IR focal plane to 125 K in less than 3 minutes. The Micro1-3 was also designed with a highly compact package that reduced the coldhead length to 55 mm, a length reduction of more than a factor of two compared with the other coldheads. This paper also describes recent design studies of 2-stage microcryocoolers capable of providing cooling at 25-100K. LMSSC is an industry leader in multiple-stage coolers, having successfully built and tested eight 2-stage coolers (typically cooling to 35-55K), and four coolers with 3 or 4 stages (for cooling to 4-10K). The 2-stage microcryocooler offers a very low mass and compact package capable of cooling HgCdTe focal planes, while providing simultaneous optics cooling at a higher temperature.

Baryon currents in QCD with compact dimensions

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

Lucini, B.; Patella, A.; Istituto Nazionale Fisica Nucleare Sezione di Pisa, Largo Pontecorvo 3, 56126 Pisa

2007-06-15

On a compact space with nontrivial cycles, for sufficiently small values of the radii of the compact dimensions, SU(N) gauge theories coupled with fermions in the fundamental representation spontaneously break charge conjugation, time reversal, and parity. We show at one loop in perturbation theory that a physical signature for this phenomenon is a nonzero baryonic current wrapping around the compact directions. The persistence of this current beyond the perturbative regime is checked by lattice simulations.

High intensity proton beam transportation through fringe field of 70 MeV compact cyclotron to beam line targets

NASA Astrophysics Data System (ADS)

Zhang, Xu; Li, Ming; Wei, Sumin; Xing, Jiansheng; Hu, Yueming; Johnson, Richard R.; Piazza, Leandro; Ryjkov, Vladimir

2016-06-01

From the stripping points, the high intensity proton beam of a compact cyclotron travels through the fringe field area of the machine to the combination magnet. Starting from there the beams with various energy is transferred to the switching magnet for distribution to the beam line targets. In the design of the extraction and transport system for the compact proton cyclotron facilities, such as the 70 MeV in France and the 100 MeV in China, the space charge effect as the beam crosses the fringe field has not been previously considered; neither has the impact on transverse beam envelope coupled from the longitudinal direction. Those have been concerned much more with the higher beam-power because of the beam loss problem. In this paper, based on the mapping data of 70 MeV cyclotron including the fringe field by BEST Cyclotron Inc (BEST) and combination magnet field by China Institute of Atomic Energy (CIAE), the beam extraction and transport are investigated for the 70 MeV cyclotron used on the SPES project at Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro (INFN-LNL). The study includes the space charge effect and longitudinal and transverse coupling mentioned above, as well as the matching of beam optics using the beam line for medical isotope production as an example. In addition, the designs of the ±45° switching magnets and the 60° bending magnet for the extracted beam with the energy from 35 MeV to 70 MeV have been made. Parts of the construction and field measurements of those magnets have been done as well. The current result shows that, the design considers the complexity of the compact cyclotron extraction area and fits the requirements of the extraction and transport for high intensity proton beam, especially at mA intensity levels.

Compact and Lightweight Sabatier Reactor for Carbon Dioxide Reduction

NASA Technical Reports Server (NTRS)

Junaedi, Christian; Hawley, Kyle; Walsh, Dennis; Roychoudhury, Subir; Abney, Morgan B.; Perry, Jay L.

2011-01-01

The utilization of CO2 to produce life support consumables, such as O2 and H2O, via the Sabatier reaction is an important aspect of NASA s cabin Atmosphere Revitalization System and In-Situ Resource Utilization architectures for both low-earth orbit and long-term manned space missions. In the current International Space Station (ISS) and other low orbit missions, metabolically-generated CO2 is removed from the cabin air and vented into space, resulting in a net loss of O2. This requires a continuous resupply of O2 via water electrolysis, and thus highlights the need for large water storage capacity. For long-duration space missions, the amount of life support consumables is limited and resupply options are practically nonexistent, thus atmosphere resource management and recycle becomes crucial to significantly reduce necessary O2 and H2O storage. Additionally, the potential use of the Martian CO2-rich atmosphere and Lunar regolith to generate life support consumables and propellant fuels is of interest to NASA. Precision Combustion, Inc. (PCI) has developed a compact, lightweight Microlith(Registered TradeMark)-based Sabatier (CO2 methanation) reactor which demonstrates the capability of achieving high CO2 conversion and near 100% CH4 selectivity at space velocities of 30,000-60,000 hr-1. The combination of the Microlith(Registered TradeMark) substrates and durable, novel catalyst coating permitted efficient Sabatier reactor operation that favors high reactant conversion, high selectivity, and long-term durability. This paper presents the reactor development and performance results at various operating conditions. Additionally, results from 100-hr durability tests and mechanical vibration tests are discussed.

Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2011-01-01

Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

Compact Radiometers Expand Climate Knowledge

NASA Technical Reports Server (NTRS)

2010-01-01

To gain a better understanding of Earth's water, energy, and carbon cycles, NASA plans to embark on the Soil Moisture Active and Passive mission in 2015. To prepare, Goddard Space Flight Center provided Small Business Innovation Research (SBIR) funding to ProSensing Inc., of Amherst, Massachusetts, to develop a compact ultrastable radiometer for sea surface salinity and soil moisture mapping. ProSensing incorporated small, low-cost, high-performance elements into just a few circuit boards and now offers two lightweight radiometers commercially. Government research agencies, university research groups, and large corporations around the world are using the devices for mapping soil moisture, ocean salinity, and wind speed.

Nonlinear sigma models with compact hyperbolic target spaces

NASA Astrophysics Data System (ADS)

Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; Stoica, Bogdan; Stokes, James

2016-06-01

We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.

Nonlinear sigma models with compact hyperbolic target spaces

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

Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.

We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in themore » O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. In conclusion, the diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.« less

Nonlinear sigma models with compact hyperbolic target spaces

DOE PAGES

Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; ...

2016-06-23

We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in themore » O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. In conclusion, the diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.« less

Compact SAR and Small Satellite Solutions for Earth Observation

NASA Astrophysics Data System (ADS)

LaRosa, M.; L'Abbate, M.

2016-12-01

Requirements for near and short term mission applications (Observation and Reconnaissance, SIGINT, Early Warning, Meteorology,..) are increasingly calling for spacecraft operational responsiveness, flexible configuration, lower cost satellite constellations and flying formations, to improve both the temporal performance of observation systems (revisit, response time) and the remote sensing techniques (distributed sensors, arrays, cooperative sensors). In answer to these users' needs, leading actors in Space Systems for EO are involved in development of Small and Microsatellites solutions. Thales Alenia Space (TAS) has started the "COMPACT-SAR" project to develop a SAR satellite characterized by low cost and reduced mass while providing, at the same time, high image quality in terms of resolution, swath size, and radiometric performance. Compact SAR will embark a X-band SAR based on a deployable reflector antenna fed by an active phased array feed. This concept allows high performance, providing capability of electronic beam steering both in azimuth and elevation planes, improving operational performance over a purely mechanically steered SAR system. Instrument provides both STRIPMAP and SPOTLIGHT modes, and thanks to very high gain antenna, can also provide a real maritime surveillance mode based on a patented Low PRF radar mode. Further developments are in progress considering missions based on Microsatellites technology, which can provide effective solutions for different user needs, such as Operational responsiveness, low cost constellations, distributed observation concept, flying formations, and can be conceived for applications in the field of Observation, Atmosphere sensing, Intelligence, Surveillance, Reconnaissance (ISR), Signal Intelligence. To satisfy these requirements, flexibility of small platforms is a key driver and especially new miniaturization technologies able to optimize the performance. An overview new micros-satellite (based on NIMBUS platform) and mission concepts is provided, such as passive SAR for multi-static imaging and tandem, Medium swath/medium resolution dual pol MICROSAR for in L-C-X band multi-application for maritime surveillance and land monitoring, applications for Space Debris monitoring, precision farming, Atmosphere sensing.

The Optical Green Valley Versus Mid-infrared Canyon in Compact Groups

NASA Technical Reports Server (NTRS)

Walker, Lisa May; Butterfield, Natalie; Johnson, Kelsey; Zucker, Catherine; Gallagher, Sarah; Konstantopoulos, Iraklis; Zabludoff, Ann; Hornschemeier, Ann E.; Tzanavaris, Panayiotis; Charlton, Jane C.

2013-01-01

Compact groups of galaxies provide conditions similar to those experienced by galaxies in the earlier universe. Recent work on compact groups has led to the discovery of a dearth of mid-infrared transition galaxies (MIRTGs) in Infrared Array Camera (3.6-8.0 micrometers) color space as well as at intermediate specific star formation rates. However, we find that in compact groups these MIRTGs have already transitioned to the optical ([g-r]) red sequence. We investigate the optical color-magnitude diagram (CMD) of 99 compact groups containing 348 galaxies and compare the optical CMD with mid-infrared (mid-IR) color space for compact group galaxies. Utilizing redshifts available from Sloan Digital Sky Survey, we identified new galaxy members for four groups. By combining optical and mid-IR data, we obtain information on both the dust and the stellar populations in compact group galaxies. We also compare with more isolated galaxies and galaxies in the Coma Cluster, which reveals that, similar to clusters, compact groups are dominated by optically red galaxies. While we find that compact group transition galaxies lie on the optical red sequence, LVL (Local Volume Legacy) + (plus) SINGS (Spitzer Infrared Nearby Galaxies Survey) mid-IR (infrared) transition galaxies span the range of optical colors. The dearth of mid-IR transition galaxies in compact groups may be due to a lack of moderately star-forming low mass galaxies; the relative lack of these galaxies could be due to their relatively small gravitational potential wells. This makes them more susceptible to this dynamic environment, thus causing them to more easily lose gas or be accreted by larger members.

Luminous Blue Compact Galaxies: Probes of galaxy assembly

NASA Astrophysics Data System (ADS)

Newton, Cassidy Louann

The life cycles of galaxies over cosmic time is yet to be fully understood. How did galaxies evolve from their formative stages to the structures we observe today? This dissertation details the identification and analysis of a sample of Luminous Blue Compact Galaxies (LBCGs), a class of galaxy in the local (z < 0.05) universe exhibiting blue colors, high surface brightness, and high star formation rates. These systems appear to be very similar in their global properties to the early evolutionary phases of most galaxies, however their locality permits detailed investigation over a broad range of the electromagnetic spectrum in contrast to the smaller angular sizes and extreme faintness of distant galaxies. We use a combination of optical, ultraviolet, and infrared data to investigate a sample of LBCGs utilizing space and ground-based data.

Permanent magnet focused X-band photoinjector

DOEpatents

Yu, David U. L.; Rosenzweig, James

2002-09-10

A compact high energy photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injection and the linac. High electron beam brightness is achieved by accelerating a tightly focused electron beam in an integrated, multi-cell, X-band rf linear accelerator (linac). The photoelectron linac employs a Plane-Wave-Transformer (PWT) design which provides strong cell-to-cell coupling, easing manufacturing tolerances and costs.

Improved Resolution Optical Time Stretch Imaging Based on High Efficiency In-Fiber Diffraction.

PubMed

Wang, Guoqing; Yan, Zhijun; Yang, Lei; Zhang, Lin; Wang, Chao

2018-01-12

Most overlooked challenges in ultrafast optical time stretch imaging (OTSI) are sacrificed spatial resolution and higher optical loss. These challenges are originated from optical diffraction devices used in OTSI, which encode image into spectra of ultrashort optical pulses. Conventional free-space diffraction gratings, as widely used in existing OTSI systems, suffer from several inherent drawbacks: limited diffraction efficiency in a non-Littrow configuration due to inherent zeroth-order reflection, high coupling loss between free-space gratings and optical fibers, bulky footprint, and more importantly, sacrificed imaging resolution due to non-full-aperture illumination for individual wavelengths. Here we report resolution-improved and diffraction-efficient OTSI using in-fiber diffraction for the first time to our knowledge. The key to overcome the existing challenges is a 45° tilted fiber grating (TFG), which serves as a compact in-fiber diffraction device offering improved diffraction efficiency (up to 97%), inherent compatibility with optical fibers, and improved imaging resolution owning to almost full-aperture illumination for all illumination wavelengths. 50 million frames per second imaging of fast moving object at 46 m/s with improved imaging resolution has been demonstrated. This conceptually new in-fiber diffraction design opens the way towards cost-effective, compact and high-resolution OTSI systems for image-based high-throughput detection and measurement.

Effect of molding pressure on fabrication of low-crystalline calcite block.

PubMed

Lin, Xin; Matsuya, Shigeki; Nakagawa, Masaharu; Terada, Yoshihiro; Ishikawa, Kunio

2008-02-01

We have reported that low-crystalline porous calcite block, which is useful as a bone substitute or a source material to prepare apatite-type bone fillers could be fabricated by exposing calcium hydroxide compact to carbon dioxide gas saturated with water vapor. In the present study, we investigated the effect of molding pressure on the transformation of calcium hydroxide into calcite and the mechanical strength of the carbonated compact. Transformation into calcite was almost completed within 72 h, however, a small amount of Ca(OH)(2) still remained unreacted at higher molding pressure because of incomplete penetration of CO(2) gas into the interparticle space due to dense packing of Ca(OH)(2) particles. On the other hand, high molding pressure resulted in an increase in diametral tensile strength (DTS) of the calcite compact formed. Critical porosity of the calcite block was calculated as approximately 68%.

Polyhedral integrated and free space optical interconnection

DOEpatents

Erteza, I.A.

1998-01-06

An optical communication system uses holographic optical elements to provide guided wave and non-guided communication, resulting in high bandwidth, high connectivity optical communications. Holograms within holographic optical elements route optical signals between elements and between nodes connected to elements. Angular and wavelength multiplexing allow the elements to provide high connectivity. The combination of guided and non-guided communication allows compact polyhedral system geometries. Guided wave communications provided by multiplexed substrate-mode holographic optical elements eases system alignment. 7 figs.

Polyhedral integrated and free space optical interconnection

DOEpatents

Erteza, Ireena A.

1998-01-01

An optical communication system uses holographic optical elements to provide guided wave and non-guided communication, resulting in high bandwidth, high connectivity optical communications. Holograms within holographic optical elements route optical signals between elements and between nodes connected to elements. Angular and wavelength multiplexing allow the elements to provide high connectivity. The combination of guided and non-guided communication allows compact polyhedral system geometries. Guided wave communications provided by multiplexed substrate-mode holographic optical elements eases system alignment.

Microtube strip heat exchanger

NASA Astrophysics Data System (ADS)

Doty, F. D.

1992-07-01

The purpose of this contract has been to explore the limits of miniaturization of heat exchangers with the goals of (1) improving the theoretical understanding of laminar heat exchangers, (2) evaluating various manufacturing difficulties, and (3) identifying major applications for the technology. A low-cost, ultra-compact heat exchanger could have an enormous impact on industry in the areas of cryocoolers and energy conversion. Compact cryocoolers based on the reverse Brayton cycle (RBC) would become practical with the availability of compact heat exchangers. Many experts believe that hardware advances in personal computer technology will rapidly slow down in four to six years unless lowcost, portable cryocoolers suitable for the desktop supercomputer can be developed. Compact refrigeration systems would permit dramatic advances in high-performance computer work stations with 'conventional' microprocessors operating at 150 K, and especially with low-cost cryocoolers below 77 K. NASA has also expressed strong interest in our MTS exchanger for space-based RBC cryocoolers for sensor cooling. We have demonstrated feasibility of higher specific conductance by a factor of five than any other work in high-temperature gas-to-gas exchangers. These laminar-flow, microtube exchangers exhibit extremely low pressure drop compared to alternative compact designs under similar conditions because of their much shorter flow length and larger total flow area for lower flow velocities. The design appears to be amenable to mass production techniques, but considerable process development remains. The reduction in materials usage and the improved heat exchanger performance promise to be of enormous significance in advanced engine designs and in cryogenics.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-12-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of atmospheric remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and comma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at 0.5 nm resolution, suitable for a number of typical DOAS applications.

NASA Tech Briefs, June 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics covered include: High-Accuracy, High-Dynamic-Range Phase-Measurement System; Simple, Compact, Safe Impact Tester; Multi-Antenna Radar Systems for Doppler Rain Measurements; 600-GHz Electronically Tunable Vector Measurement System; Modular Architecture for the Measurement of Space Radiation; VLSI Design of a Turbo Decoder; Architecture of an Autonomous Radio Receiver; Improved On-Chip Measurement of Delay in an FPGA or ASIC; Resource Selection and Ranking; Accident/Mishap Investigation System; Simplified Identification of mRNA or DNA in Whole Cells; Printed Multi-Turn Loop Antennas for RF Biotelemetry; Making Ternary Quantum Dots From Single-Source Precursors; Improved Single-Source Precursors for Solar-Cell Absorbers; Spray CVD for Making Solar-Cell Absorber Layers; Glass/BNNT Composite for Sealing Solid Oxide Fuel Cells; A Method of Assembling Compact Coherent Fiber-Optic Bundles; Manufacturing Diamond Under Very High Pressure; Ring-Resonator/Sol-Gel Interferometric Immunosensor; Compact Fuel-Cell System Would Consume Neat Methanol; Algorithm Would Enable Robots to Solve Problems Creatively; Hypothetical Scenario Generator for Fault-Tolerant Diagnosis; Smart Data Node in the Sky; Pseudo-Waypoint Guidance for Proximity Spacecraft Maneuvers; Update on Controlling Herds of Cooperative Robots; and Simulation and Testing of Maneuvering of a Planetary Rover.

Faithful actions of locally compact quantum groups on classical spaces

NASA Astrophysics Data System (ADS)

Goswami, Debashish; Roy, Sutanu

2017-07-01

We construct examples of locally compact quantum groups coming from bicrossed product construction, including non-Kac ones, which can faithfully and ergodically act on connected classical (noncompact) smooth manifolds. However, none of these actions can be isometric in the sense of Goswami (Commun Math Phys 285(1):141-160, 2009), leading to the conjecture that the result obtained by Goswami and Joardar (Rigidity of action of compact quantum groups on compact, connected manifolds, 2013. arXiv:1309.1294) about nonexistence of genuine quantum isometry of classical compact connected Riemannian manifolds may hold in the noncompact case as well.

Observational properties of compact groups of galaxies

NASA Technical Reports Server (NTRS)

Hickson, Paul

1990-01-01

Compact groups are small, relatively isolated, systems of galaxies with projected separations comparable to the diameters of the galaxies themselves. Two well-known examples are Stephan's Quintet (Stephan, 1877) and Seyfert's Sextet (Seyfert 1948a,b). In groups such as these, the apparent space density of galaxies approaches 10(exp 6) Mpc(sub -3), denser even than the cores of rich clusters. The apparent unlikeliness of the chance occurrence of such tight groupings lead Ambartsumyan (1958, 1975) to conclude that compact groups must be physically dense systems. This view is supported by clear signs of galaxy interactions that are seen in many groups. Spectroscopic observations reveal that typical relative velocities of galaxies in the groups are comparable to their internal stellar velocities. This should be conducive to strong gravitational interactions - more so than in rich clusters, where galaxy velocities are typically much higher. This suggests that compact groups could be excellent laboratories in which to study galaxy interactions and their effects. Compact groups often contain one or more galaxies whose redshift differs greatly from those of the other group members. If these galaxies are at the same distance as the other members, either entire galaxies are being ejected at high velocities from these groups, or some new physical phenomena must be occurring. If their redshifts are cosmological, we must explain why so many discordant galaxies are found in compact groups. In recent years much progress has been made in addressing these questions. Here, the author discusses the current observational data on compact groups and their implications.

Compaction managed mirror bend achromat

DOEpatents

Douglas, David [Yorktown, VA

2005-10-18

A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

Topology-preserving quantum deformation with non-numerical parameter

NASA Astrophysics Data System (ADS)

Aukhadiev, Marat; Grigoryan, Suren; Lipacheva, Ekaterina

2013-11-01

We introduce a class of compact quantum semigroups, that we call semigroup deformations of compact Abelian qroups. These objects arise from reduced semigroup -algebras, the generalization of the Toeplitz algebra. We study quantum subgroups, quantum projective spaces and quantum quotient groups for such objects, and show that the group is contained as a compact quantum subgroup in the deformation of itself. The connection with the weak Hopf algebra notion is described. We give a grading on the -algebra of the compact quantum semigroups constructed.

A partial structural and functional rescue of a retinitis pigmentosa model with compacted DNA nanoparticles.

PubMed

Cai, Xue; Nash, Zack; Conley, Shannon M; Fliesler, Steven J; Cooper, Mark J; Naash, Muna I

2009-01-01

Previously we have shown that compacted DNA nanoparticles can drive high levels of transgene expression after subretinal injection in the mouse eye. Here we delivered compacted DNA nanoparticles containing a therapeutic gene to the retinas of a mouse model of retinitis pigmentosa. Nanoparticles containing the wild-type retinal degeneration slow (Rds) gene were injected into the subretinal space of rds(+/-) mice on postnatal day 5. Gene expression was sustained for up to four months at levels up to four times higher than in controls injected with saline or naked DNA. The nanoparticles were taken up into virtually all photoreceptors and mediated significant structural and biochemical rescue of the disease without histological or functional evidence of toxicity. Electroretinogram recordings showed that nanoparticle-mediated gene transfer restored cone function to a near-normal level in contrast to transfer of naked plasmid DNA. Rod function was also improved. These findings demonstrate that compacted DNA nanoparticles represent a viable option for development of gene-based interventions for ocular diseases and obviate major barriers commonly encountered with non-viral based therapies.

Linear electric field mass spectrometry

DOEpatents

McComas, David J.; Nordholt, Jane E.

1992-01-01

A mass spectrometer and methods for mass spectrometry. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field.

SpaceCube Mini

NASA Technical Reports Server (NTRS)

Lin, Michael; Petrick, David; Geist, Alessandro; Flatley, Thomas

2012-01-01

This version of the SpaceCube will be a full-fledged, onboard space processing system capable of 2500+ MIPS, and featuring a number of plug-andplay gigabit and standard interfaces, all in a condensed 3x3x3 form factor [less than 10 watts and less than 3 lb (approximately equal to 1.4 kg)]. The main processing engine is the Xilinx SIRF radiation- hardened-by-design Virtex-5 FX-130T field-programmable gate array (FPGA). Even as the SpaceCube 2.0 version (currently under test) is being targeted as the platform of choice for a number of the upcoming Earth Science Decadal Survey missions, GSFC has been contacted by customers who wish to see a system that incorporates key features of the version 2.0 architecture in an even smaller form factor. In order to fulfill that need, the SpaceCube Mini is being designed, and will be a very compact and low-power system. A similar flight system with this combination of small size, low power, low cost, adaptability, and extremely high processing power does not otherwise exist, and the SpaceCube Mini will be of tremendous benefit to GSFC and its partners. The SpaceCube Mini will utilize space-grade components. The primary processing engine of the Mini is the Xilinx Virtex-5 SIRF FX-130T radiation-hardened-by-design FPGA for critical flight applications in high-radiation environments. The Mini can also be equipped with a commercial Xilinx Virtex-5 FPGA with integrated PowerPCs for a low-cost, high-power computing platform for use in the relatively radiation- benign LEOs (low-Earth orbits). In either case, this version of the Space-Cube will weigh less than 3 pounds (.1.4 kg), conform to the CubeSat form-factor (10x10x10 cm), and will be low power (less than 10 watts for typical applications). The SpaceCube Mini will have a radiation-hardened Aeroflex FPGA for configuring and scrubbing the Xilinx FPGA by utilizing the onboard FLASH memory to store the configuration files. The FLASH memory will also be used for storing algorithm and application code for the PowerPCs and the Xilinx FPGA. In addition, it will feature highspeed DDR SDRAM (double data rate synchronous dynamic random-access memory) to store the instructions and data of active applications. This version will also feature SATA-II and Gigabit Ethernet interfaces. Furthermore, there will also be general-purpose, multi-gigabit interfaces. In addition, the system will have dozens of transceivers that can support LVDS (low-voltage differential signaling), RS-422, or SpaceWire. The SpaceCube Mini includes an I/O card that can be customized to meet the needs of each mission. This version of the SpaceCube will be designed so that multiple Minis can be networked together using SpaceWire, Ethernet, or even a custom protocol. Scalability can be provided by networking multiple SpaceCube Minis together. Rigid-Flex technology is being targeted for the construction of the SpaceCube Mini, which will make the extremely compact and low-weight design feasible. The SpaceCube Mini is designed to fit in the compact CubeSat form factor, thus allowing deployment in a new class of missions that the previous SpaceCube versions were not suited for. At the time of this reporting, engineering units should be available in the summer 2012.

Smart Optical RAM for Fast Information Management and Analysis

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang

1998-01-01

Statement of Problem Instruments for high speed and high capacity in-situ data identification, classification and storage capabilities are needed by NASA for the information management and analysis of extremely large volume of data sets in future space exploration, space habitation and utilization, in addition to the various missions to planet-earth programs. Parameters such as communication delays, limited resources, and inaccessibility of human manipulation require more intelligent, compact, low power, and light weight information management and data storage techniques. New and innovative algorithms and architecture using photonics will enable us to meet these challenges. The technology has applications for other government and public agencies.

Quantum dressing orbits on compact groups

NASA Astrophysics Data System (ADS)

Jurčo, Branislav; Šťovíček, Pavel

1993-02-01

The quantum double is shown to imply the dressing transformation on quantum compact groups and the quantum Iwasawa decompositon in the general case. Quantum dressing orbits are described explicitly as *-algebras. The dual coalgebras consisting of differential operators are related to the quantum Weyl elements. Besides, the differential geometry on a quantum leaf allows a remarkably simple construction of irreducible *-representations of the algebras of quantum functions. Representation spaces then consist of analytic functions on classical phase spaces. These representations are also interpreted in the framework of quantization in the spirit of Berezin applied to symplectic leaves on classical compact groups. Convenient “coherent states” are introduced and a correspondence between classical and quantum observables is given.

Universal moduli spaces of Riemann surfaces

NASA Astrophysics Data System (ADS)

Ji, Lizhen; Jost, Jürgen

2017-04-01

We construct a moduli space for Riemann surfaces that is universal in the sense that it represents compact Riemann surfaces of any finite genus. This moduli space is a connected complex subspace of an infinite dimensional complex space, and is stratified according to genus such that each stratum has a compact closure, and it carries a metric and a measure that induce a Riemannian metric and a finite volume measure on each stratum. Applications to the Plateau-Douglas problem for minimal surfaces of varying genus and to the partition function of Bosonic string theory are outlined. The construction starts with a universal moduli space of Abelian varieties. This space carries a structure of an infinite dimensional locally symmetric space which is of interest in its own right. The key to our construction of the universal moduli space then is the Torelli map that assigns to every Riemann surface its Jacobian and its extension to the Satake-Baily-Borel compactifications.

Incorporating Sediment Compaction Into a Gravitationally Self-consistent Model for Global Sea-level Change

NASA Astrophysics Data System (ADS)

Ferrier, K.; Mitrovica, J. X.

2015-12-01

In sedimentary deltas and fans, sea-level changes are strongly modulated by the deposition and compaction of marine sediment. The deposition of sediment and incorporation of water into the sedimentary pore space reduces sea level by increasing the elevation of the seafloor, which reduces the thickness of sea-water above the bed. In a similar manner, the compaction of sediment and purging of water out of the sedimentary pore space increases sea level by reducing the elevation of the seafloor, which increases the thickness of sea water above the bed. Here we show how one can incorporate the effects of sediment deposition and compaction into the global, gravitationally self-consistent sea-level model of Dalca et al. (2013). Incorporating sediment compaction requires accounting for only one additional quantity that had not been accounted for in Dalca et al. (2013): the mean porosity in the sediment column. We provide a general analytic framework for global sea-level changes including sediment deposition and compaction, and we demonstrate how sea level responds to deposition and compaction under one simple parameterization for compaction. The compaction of sediment generates changes in sea level only by changing the elevation of the seafloor. That is, sediment compaction does not affect the mass load on the crust, and therefore does not generate perturbations in crustal elevation or the gravity field that would further perturb sea level. These results have implications for understanding sedimentary effects on sea-level changes and thus for disentangling the various drivers of sea-level change. ReferencesDalca A.V., Ferrier K.L., Mitrovica J.X., Perron J.T., Milne G.A., Creveling J.R., 2013. On postglacial sea level - III. Incorporating sediment redistribution. Geophysical Journal International, doi: 10.1093/gji/ggt089.

The Mini-SPT (Space Particle Telescope) for dual use: Precision flux measurement of low energy proton electron and heavy ion with tracking capability and A compact, low-cost realtime local radiation hazard/alarm detector to be used on board a satellite

NASA Astrophysics Data System (ADS)

Alpat, Behcet; Ergin, Tulun; Kalemci, Emrah

2016-07-01

The Mini-SPT project is the first, and most important, step towards the ambitious goal of creating a low-cost, compact, radiation hardened and high performance space particle telescope that can be mounted, in the near future, as standard particle detector on any satellite. Mini-SPT will be capable of providing high quality physics data on local space environment. In particular high precision flux measurement and tracking of low energy protons and electrons on different orbits with same instrumentation is of paramount importance for studies as geomagnetically trapped fluxes and space weather dynamics, dark matter search, low energy proton anisotropy and its effects on ICs as well as the solar protons studies. In addition, it will provide real-time "differentiable warnings" about the local space radiation hazard to other electronics systems on board the hosting satellite, including different criticality levels and alarm signals to activate mitigation techniques whenever this is strictly necessary to protect them from temporary/permanent failures. A real-time warning system will help satellite subsystems to save significant amount of power and memory with respect to other conventional techniques where the "mitigation" solutions are required to be active during entire mission life. The Mini-SPT will combine the use of technologies developed in cutting-edge high energy physics experiments (including technology from CMS experiments at CERN) and the development of new charged particle detecting systems for their use for the first time in space. The Mini-SPT essential objective is, by using for the first time in space SIPMs (Silicon Photomultipliers) technology for TOF and energy measurements, the production of high quality data with a good time, position and energy resolutions. The mini-SPT will consists of three main sub-units: a- A tracking and dE/dX measuring sub-detector which will be based on silicon pixel detectors (SPD) coupled to the rad-hard chip ROC-DIG (Read Out Chip-Digital version), developed and bump bonded to high accuracy radiation hardened particle barrel pixel detector in CMS (Compact Magnetic Solenoid) experiment of LHC (Large Hadron Collider) at CERN-Geneva b- The calorimeter (CCAL) system will consist of a scintillating crystal optically coupled to an array of silicon photomultipliers (SIPMs) to read out the photons created in the crystal by impinging charged particles. c- The TOF and associated trigger compose the third detecting sub-unit of the Mini-SPT , consisting basically of two small (~2 cm diameter) plastic scintillator layers The challenge is to develop a high performing scientific payload to fit in 6U Cubesat format with very good electron, proton and heavier particles separation as well as direct energy spectra measurement for protons up to almost 1 GeV and for electrons up to few tens of MeV. The angular acceptance of full mini-SPT payload is 6-5 degrees. If only tracking elements (SPDs) are considered the opening angle increases15 degrees.

Ultra-compact high-performance MCT MWIR engine

NASA Astrophysics Data System (ADS)

Lutz, H.; Breiter, R.; Eich, D.; Figgemeier, H.; Oelmaier, R.; Rutzinger, S.; Schenk, H.; Wendler, J.

2017-02-01

Size, weight and power (SWaP) reduction is highly desired by applications such as sights for the dismounted soldier or small gimbals for UAVs. But why have high performance and small size of IR systems inevitably exclude each other? Namely, recent development progress in the fields of miniature cryocoolers, short dewars and high operating temperature (HOT) FPAs combined with pitch size reduction opens the door for very compact MWIR-modules while keeping high electro-optical performance. Now, AIM has realized first prototypes of an ultra-compact high-performance MWIR engine in a total volume of only 18cl (60mm length x 60mm height x 50mm width). Impressive SWaP characteristics are completed by a total weight below 400g and a power consumption < 4W in basic imaging mode. The engine consists of a XGA-format (1024x768) MCT detector array with 10μm pitch and a low power consuming ROIC. It is cooled down to a typical operating temperature of 160K by the miniature linear cryocooler SX020. The dewar uses a short coldfinger and is designed to reduce the heat load as much as possible. The cooler drive electronics is implemented in the CCE layout in order to reduce the required space of the printed boards and to save power. Uncorrected 14bit video data is provided via Camera Link. Optionally, a small image processing board can be stacked on top of the CCE to gain access to basic functions such as BPR, 2- point NUC and dynamic reduction. This paper will present the design, functionalities and performance data of the ultra-compact MCT MWIR engine operated at HOT.

Design, fabrication and space suitability tests of wide field of view, ultra-compact, and high resolution telescope for space application.

PubMed

Tumarina, M; Ryazanskiy, M; Jeong, S; Hong, G; Vedenkin, N; Park, I H; Milov, A

2018-02-05

We report on the design, manufacture, and testing of an ultra-compact telescope for 16 unit (16U) CubeSats for Earth and space observation. This telescope provides 1 arcsec resolution at a 2.9 degree field of view. Dimensions are optimized to 230 × 230 × 330mm 3 with a mass of less than 6kg including support structure. Our catadioptric 5-element design consists of a full-aperture corrector, a Mangin primary mirror (PM), a secondary mirror (SM), and a 2-lens field corrector. The focal length is 745mm, and squared-circular aperture has an equivalent diameter of 241mm. The designed modulation transfer function (MTF) is 0.275 for the entire unit including baffles at a Nyquist frequency of 161 cycles/mm for the 450-800nm band. As one of the distinguishing features of our state-of-the-art design, all optical surfaces are spherical to simplify adjustment. For the best thermal stability, all optical elements are produced from fused silica. We describe the details of design, adjustment, and laboratory performance tests for space environments in accordance with the requirements for in-orbit operation onboard Earth-observation micro-satellites to be launched in 2018.

Mechanical monolithic compact sensors for real-time linear and angular broadband low frequency monitoring and control of spacecrafts and satellites

NASA Astrophysics Data System (ADS)

Barone, F.; Giordano, G.

2017-09-01

In this paper we describe the characteristics and performances of a monolithic sensor designed for low frequency motion measurement of spacecrafts and satellites, whose mechanics is based on the UNISA Folded Pendulum. The latter, developed for ground-based applications, exhibits unique features (compactness, lightness, scalability, low resonance frequency and high quality factor), consequence of the action of the gravitational force on its inertial mass. In this paper we introduce and discuss the general methodology used to extend the application of ground-based folded pendulums to space, also in total absence of gravity, still keeping all their peculiar features and characteristics.

Intelligent neuroprocessors for in-situ launch vehicle propulsion systems health management

NASA Technical Reports Server (NTRS)

Gulati, S.; Tawel, R.; Thakoor, A. P.

1993-01-01

Efficacy of existing on-board propulsion systems health management systems (HMS) are severely impacted by computational limitations (e.g., low sampling rates); paradigmatic limitations (e.g., low-fidelity logic/parameter redlining only, false alarms due to noisy/corrupted sensor signatures, preprogrammed diagnostics only); and telemetry bandwidth limitations on space/ground interactions. Ultra-compact/light, adaptive neural networks with massively parallel, asynchronous, fast reconfigurable and fault-tolerant information processing properties have already demonstrated significant potential for inflight diagnostic analyses and resource allocation with reduced ground dependence. In particular, they can automatically exploit correlation effects across multiple sensor streams (plume analyzer, flow meters, vibration detectors, etc.) so as to detect anomaly signatures that cannot be determined from the exploitation of single sensor. Furthermore, neural networks have already demonstrated the potential for impacting real-time fault recovery in vehicle subsystems by adaptively regulating combustion mixture/power subsystems and optimizing resource utilization under degraded conditions. A class of high-performance neuroprocessors, developed at JPL, that have demonstrated potential for next-generation HMS for a family of space transportation vehicles envisioned for the next few decades, including HLLV, NLS, and space shuttle is presented. Of fundamental interest are intelligent neuroprocessors for real-time plume analysis, optimizing combustion mixture-ratio, and feedback to hydraulic, pneumatic control systems. This class includes concurrently asynchronous reprogrammable, nonvolatile, analog neural processors with high speed, high bandwidth electronic/optical I/O interfaced, with special emphasis on NASA's unique requirements in terms of performance, reliability, ultra-high density ultra-compactness, ultra-light weight devices, radiation hardened devices, power stringency, and long life terms.

Active optics for next generation space telescopes

NASA Astrophysics Data System (ADS)

Costes, V.; Perret, L.; Laubier, D.; Delvit, J. M.; Imbert, C.; Cadiergues, L.; Faure, C.

2017-09-01

High resolution observation systems need bigger and bigger telescopes. The design of such telescopes is a key issue for the whole satellite. In order to improve the imaging resolution with minimum impact on the satellite, a big effort must be made to improve the telescope compactness. Compactness is also important for the agility of the satellite and for the size and cost of the launcher. This paper shows how compact a high resolution telescope can be. A diffraction limited telescope can be less than ten times shorter than its focal length. But the compactness impacts drastically the opto-mechanical sensitivity and the optical performances. Typically, a gain of a factor of 2 leads to a mechanical tolerance budget 6 times more difficult. The need to implement active optics for positioning requirements raises very quickly. Moreover, the capability to compensate shape defaults of the primary mirror is the way to simplify the mirror manufacture, to mitigate the development risks and to minimize the cost. The larger the primary mirror is, the more interesting it is to implement active optics for shape compensations. CNES is preparing next generation of earth observation satellite in the frame of OTOS (Observation de la Terre Optique Super-Résolue; High resolution earth observing optical system). OTOS is a technology program. In particular, optical technological developments and breadboards dedicated to active optics are on-going. The aim is to achieve TRL 5 to TRL6 for these new technologies and to validate the global performances of such an active telescope.

Testing of Compact Bolted Fasteners with Insulation and Friction-Enhanced Shims for NCSX

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

L. E. Dudek, J.H. Chrzanowski, G. Gettelfinger, P. Heitzenroeder, S. Jurczynski, M. Viola and K. Freudenberg

The fastening of the National Compact Stellarator Experiment's (NCSX) modular coils presented a number of engineering and manufacturing challenges due to the high magnetic forces, need to control induced currents, tight tolerances and restrictive space envelope. A fastening method using high strength studs, jack nuts, insulating spacers, bushings and alumina coated shims was developed which met the requirements. A test program was conducted to verify the design. The tests included measurements of flatness of the spacers, determination of contact area, torque vs. tension of the studs and jack nuts, friction coefficient tests on the alumina and G-10 insulators, electrical tests,more » and tension relaxation tests due to temperature excursions from room temperature to liquid nitrogen temperatures. This paper will describe the design and the results of the test program.« less

A compact Acousto-Optic Lens for 2D and 3D femtosecond based 2-photon microscopy.

PubMed

Kirkby, Paul A; Srinivas Nadella, K M Naga; Silver, R Angus

2010-06-21

We describe a high speed 3D Acousto-Optic Lens Microscope (AOLM) for femtosecond 2-photon imaging. By optimizing the design of the 4 AO Deflectors (AODs) and by deriving new control algorithms, we have developed a compact spherical AOL with a low temporal dispersion that enables 2-photon imaging at 10-fold lower power than previously reported. We show that the AOLM can perform high speed 2D raster-scan imaging (>150 Hz) without scan rate dependent astigmatism. It can deflect and focus a laser beam in a 3D random access sequence at 30 kHz and has an extended focusing range (>137 mum; 40X 0.8NA objective). These features are likely to make the AOLM a useful tool for studying fast physiological processes distributed in 3D space.

Sunlight supply and gas exchange systems in microalgal bioreactor

NASA Technical Reports Server (NTRS)

Mori, K.; Ohya, H.; Matsumoto, K.; Furune, H.

1987-01-01

The bioreactor with sunlight supply system and gas exchange systems presented has proved feasible in ground tests and shows much promise for space use as a closed ecological life support system device. The chief conclusions concerning the specification of total system needed for a life support system for a man in a space station are the following: (1) Sunlight supply system - compactness and low electrical consumption; (2) Bioreactor system - high density and growth rate of chlorella; and (3) Gas exchange system - enough for O2 production and CO2 assimilation.

Spatially organized «vertical city» as a synthesis of tall buildings and airships

NASA Astrophysics Data System (ADS)

Gagulina, Olga; Matovnikov, Sergei

2018-03-01

The paper explores the compact city concept based on the «spatial» urban development principles and describes the prerequisites and possible methods to move from «horizontal» planning to «vertical» urban environments. It highlights the close connection between urban space, high-rise city landscape and conveyance options and sets out the ideas for upgrading the existing architectural and urban planning principles. It also conceptualizes the use of airships to create additional spatial connections between urban structure elements and high-rise buildings. Functional changes are considered in creating both urban environment and internal space of tall buildings, and the environmental aspects of the new spatial model are brought to light. The paper delineates the prospects for making a truly «spatial» multidimensional city space.

On the Ck-embedding of Lorentzian manifolds in Ricci-flat spaces

NASA Astrophysics Data System (ADS)

Avalos, R.; Dahia, F.; Romero, C.

2018-05-01

In this paper, we investigate the problem of non-analytic embeddings of Lorentzian manifolds in Ricci-flat semi-Riemannian spaces. In order to do this, we first review some relevant results in the area and then motivate both the mathematical and physical interests in this problem. We show that any n-dimensional compact Lorentzian manifold (Mn, g), with g in the Sobolev space Hs+3, s >n/2 , admits an isometric embedding in a (2n + 2)-dimensional Ricci-flat semi-Riemannian manifold. The sharpest result available for these types of embeddings, in the general setting, comes as a corollary of Greene's remarkable embedding theorems R. Greene [Mem. Am. Math. Soc. 97, 1 (1970)], which guarantee the embedding of a compact n-dimensional semi-Riemannian manifold into an n(n + 5)-dimensional semi-Euclidean space, thereby guaranteeing the embedding into a Ricci-flat space with the same dimension. The theorem presented here improves this corollary in n2 + 3n - 2 codimensions by replacing the Riemann-flat condition with the Ricci-flat one from the beginning. Finally, we will present a corollary of this theorem, which shows that a compact strip in an n-dimensional globally hyperbolic space-time can be embedded in a (2n + 2)-dimensional Ricci-flat semi-Riemannian manifold.

Where are compact groups in the local Universe?

NASA Astrophysics Data System (ADS)

Díaz-Giménez, Eugenia; Zandivarez, Ariel

2015-06-01

Aims: The purpose of this work is to perform a statistical analysis of the location of compact groups in the Universe from observational and semi-analytical points of view. Methods: We used the velocity-filtered compact group sample extracted from the Two Micron All Sky Survey for our analysis. We also used a new sample of galaxy groups identified in the 2M++ galaxy redshift catalogue as tracers of the large-scale structure. We defined a procedure to search in redshift space for compact groups that can be considered embedded in other overdense systems and applied this criterion to several possible combinations of different compact and galaxy group subsamples. We also performed similar analyses for simulated compact and galaxy groups identified in a 2M++ mock galaxy catalogue constructed from the Millennium Run Simulation I plus a semi-analytical model of galaxy formation. Results: We observed that only ~27% of the compact groups can be considered to be embedded in larger overdense systems, that is, most of the compact groups are more likely to be isolated systems. The embedded compact groups show statistically smaller sizes and brighter surface brightnesses than non-embedded systems. No evidence was found that embedded compact groups are more likely to inhabit galaxy groups with a given virial mass or with a particular dynamical state. We found very similar results when the analysis was performed using mock compact and galaxy groups. Based on the semi-analytical studies, we predict that 70% of the embedded compact groups probably are 3D physically dense systems. Finally, real space information allowed us to reveal the bimodal behaviour of the distribution of 3D minimum distances between compact and galaxy groups. Conclusions: The location of compact groups should be carefully taken into account when comparing properties of galaxies in environments that are a priori different. Appendices are available in electronic form at http://www.aanda.orgFull Tables B.1 and B.2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A61

Ultra-Compact Raman Spectrometer for Planetary Explorations

NASA Technical Reports Server (NTRS)

Davis, Derek; Hornef, James; Lucas, John; Elsayed-Ali, Hani; Abedin, M. Nurul

2016-01-01

To develop a compact Raman spectroscopy system with features that will make it suitable for future space missions which require surface landing. Specifically, this system will be appropriate for any mission in which planetary surface samples need to be measured and analyzed.

Improved Sand-Compaction Method for Lost-Foam Metal Casting

NASA Technical Reports Server (NTRS)

Bakhtiyarov, Sayavur I.; Overfelt, Ruel A.

2008-01-01

An improved method of filling a molding flask with sand and compacting the sand around a refractory-coated foam mold pattern has been developed for incorporation into the lost-foam metal-casting process. In comparison with the conventional method of sand filling and compaction, this method affords more nearly complete filling of the space around the refractory-coated foam mold pattern and more thorough compaction of the sand. In so doing, this method enables the sand to better support the refractory coat under metallostatic pressure during filling of the mold with molten metal.

A modular and compact portable mini-endstation for high-precision, high-speed fixed target serial crystallography at FEL and synchrotron sources

DOE PAGES

Sherrell, Darren A.; Foster, Andrew J.; Hudson, Lee; ...

2015-01-01

The design and implementation of a compact and portable sample alignment system suitable for use at both synchrotron and free-electron laser (FEL) sources and its performance are described. The system provides the ability to quickly and reliably deliver large numbers of samples using the minimum amount of sample possible, through positioning of fixed target arrays into the X-ray beam. The combination of high-precision stages, high-quality sample viewing, a fast controller and a software layer overcome many of the challenges associated with sample alignment. A straightforward interface that minimizes setup and sample changeover time as well as simplifying communication with themore » stages during the experiment is also described, together with an intuitive naming convention for defining, tracking and locating sample positions. Lastly, the setup allows the precise delivery of samples in predefined locations to a specific position in space and time, reliably and simply.« less

Flow Field Dynamics in a High-g Ultra-Compact Combustor

DTIC Science & Technology

2016-12-01

6.1.3.1. Baseline Exit Temperatures .............................................................. 308 x 6.1.3.2. Exit Temperature Effects Due to...through improved thrust-specific fuel consumption ; however, implementation of an effective combustion scheme in the constrained space between turbine...their influence on the combustion process, and the resultant effect on exit temperature profiles and emissions (as detailed in the following section

Linear electric field mass spectrometry

DOEpatents

McComas, D.J.; Nordholt, J.E.

1992-12-01

A mass spectrometer and methods for mass spectrometry are described. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field. 8 figs.

Compact laser interferometer for translation and tilt measurement as optical readout for the LISA inertial sensor

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Gohlke, Martin; Weise, Dennis; Johann, Ulrich; Peters, Achim; Braxmaier, Claus

2007-10-01

The space mission LISA (Laser Interferometer Space Antenna) aims at detecting gravitational waves in the frequency range 30 μ Hz to 1Hz. Free flying proof masses inside the satellites act as inertial sensors and represent the end mirrors of the interferometer. In the current baseline design, LISA utilizes an optical readout of the position and tilt of the proof mass with respect to the satellite housing. This readout must have ~ 5pm/√Hz sensitivity for the translation measurement (for frequencies above 2.8mHz with an ƒ -2 relaxation down to 30 μHz) and ~ 10 nrad/√Hz sensitivity for the tilt measurement (for frequencies above 0.1mHz with an ƒ -1 relaxation down to 30 μHz). The University of Applied Sciences Konstanz (HTWG) - in collaboration with Astrium GmbH, Friedrichshafen, and the Humboldt-University Berlin - therefore develops a highly symmetric heterodyne interferometer implementing differential wavefront sensing for the tilt measurement. We realized a mechanically highly stable and compact setup. In a second, improved setup we measured initial noise levels below 5 pm/√Hz and 10 nrad/√Hz, respectively, for frequencies above 10mHz.

Vibration and stress analysis of soft-bonded shuttle insulation tiles. Modal analysis with compact widely space stringers

NASA Technical Reports Server (NTRS)

Ojalvo, I. U.; Austin, F.; Levy, A.

1974-01-01

An efficient iterative procedure is described for the vibration and modal stress analysis of reusable surface insulation (RSI) of multi-tiled space shuttle panels. The method, which is quite general, is rapidly convergent and highly useful for this application. A user-oriented computer program based upon this procedure and titled RESIST (REusable Surface Insulation Stresses) has been prepared for the analysis of compact, widely spaced, stringer-stiffened panels. RESIST, which uses finite element methods, obtains three dimensional tile stresses in the isolator, arrestor (if any) and RSI materials. Two dimensional stresses are obtained in the tile coating and the stringer-stiffened primary structure plate. A special feature of the program is that all the usual detailed finite element grid data is generated internally from a minimum of input data. The program can accommodate tile idealizations with up to 850 nodes (2550 degrees-of-freedom) and primary structure idealizations with a maximum of 10,000 degrees-of-freedom. The primary structure vibration capability is achieved through the development of a new rapid eigenvalue program named ALARM (Automatic LArge Reduction of Matrices to tridiagonal form).

Efficient measurement of large light source near-field color and luminance distributions for optical design and simulation

NASA Astrophysics Data System (ADS)

Kostal, Hubert; Kreysar, Douglas; Rykowski, Ronald

2009-08-01

The color and luminance distributions of large light sources are difficult to measure because of the size of the source and the physical space required for the measurement. We describe a method for the measurement of large light sources in a limited space that efficiently overcomes the physical limitations of traditional far-field measurement techniques. This method uses a calibrated, high dynamic range imaging colorimeter and a goniometric system to move the light source through an automated measurement sequence in the imaging colorimeter's field-of-view. The measurement is performed from within the near-field of the light source, enabling a compact measurement set-up. This method generates a detailed near-field color and luminance distribution model that can be directly converted to ray sets for optical design and that can be extrapolated to far-field distributions for illumination design. The measurements obtained show excellent correlation to traditional imaging colorimeter and photogoniometer measurement methods. The near-field goniometer approach that we describe is broadly applicable to general lighting systems, can be deployed in a compact laboratory space, and provides full near-field data for optical design and simulation.

Complete spacelike hypersurfaces in orthogonally splitted spacetimes

NASA Astrophysics Data System (ADS)

Colombo, Giulio; Rigoli, Marco

2017-10-01

We provide some "half-space theorems" for spacelike complete non-compact hypersurfaces into orthogonally splitted spacetimes. In particular we generalize some recent work of Rubio and Salamanca on maximal spacelike compact hypersurfaces. Beside compactness, we also relax some of their curvature assumptions and even consider the case of nonconstant mean curvature bounded from above. The analytic tools used in various arguments are based on some forms of the weak maximum principle.

Elliptic complexes over C∗-algebras of compact operators

NASA Astrophysics Data System (ADS)

Krýsl, Svatopluk

2016-03-01

For a C∗-algebra A of compact operators and a compact manifold M, we prove that the Hodge theory holds for A-elliptic complexes of pseudodifferential operators acting on smooth sections of finitely generated projective A-Hilbert bundles over M. For these C∗-algebras and manifolds, we get a topological isomorphism between the cohomology groups of an A-elliptic complex and the space of harmonic elements of the complex. Consequently, the cohomology groups appear to be finitely generated projective C∗-Hilbert modules and especially, Banach spaces. We also prove that in the category of Hilbert A-modules and continuous adjointable Hilbert A-module homomorphisms, the property of a complex of being self-adjoint parametrix possessing characterizes the complexes of Hodge type.

Compact Microscope Imaging System With Intelligent Controls Improved

NASA Technical Reports Server (NTRS)

McDowell, Mark

2004-01-01

The Compact Microscope Imaging System (CMIS) with intelligent controls is a diagnostic microscope analysis tool with intelligent controls for use in space, industrial, medical, and security applications. This compact miniature microscope, which can perform tasks usually reserved for conventional microscopes, has unique advantages in the fields of microscopy, biomedical research, inline process inspection, and space science. Its unique approach integrates a machine vision technique with an instrumentation and control technique that provides intelligence via the use of adaptive neural networks. The CMIS system was developed at the NASA Glenn Research Center specifically for interface detection used for colloid hard spheres experiments; biological cell detection for patch clamping, cell movement, and tracking; and detection of anode and cathode defects for laboratory samples using microscope technology.

The design and fabrication of a prototype trash compacting unit. [for long duration space missions

NASA Technical Reports Server (NTRS)

1973-01-01

A prototype trash compactor, that is compatible with the anticipated requirements of future long-term space missions, is described. Preliminary problem definition studies were conducted to identify typical types and quantities of waste materials to be expected from a typical mission. Bench-scale compaction tests were then conducted on typical waste materials to determine force/compaction curves. These data were used to design a boilerplate compactor that was fabricated to prove the feasibility of the basic design concept. A final design was then prepared from which the deliverable unit was fabricated. Design concepts are presented for suggested further development of the compactor, including a version that is capable of handling wet biodegradable wastes.

Compact time- and space-integrating SAR processor: design and development status

NASA Astrophysics Data System (ADS)

Haney, Michael W.; Levy, James J.; Christensen, Marc P.; Michael, Robert R., Jr.; Mock, Michael M.

1994-06-01

Progress toward a flight demonstration of the acousto-optic time- and space- integrating real-time SAR image formation processor program is reported. The concept overcomes the size and power consumption limitations of electronic approaches by using compact, rugged, and low-power analog optical signal processing techniques for the most computationally taxing portions of the SAR imaging problem. Flexibility and performance are maintained by the use of digital electronics for the critical low-complexity filter generation and output image processing functions. The results reported include tests of a laboratory version of the concept, a description of the compact optical design that will be implemented, and an overview of the electronic interface and controller modules of the flight-test system.

FACT, Mega-ROSA, SOLAROSA

NASA Technical Reports Server (NTRS)

Spence, Brian; White, Steve; Schmid, Kevin; Douglas Mark

2012-01-01

The Flexible Array Concentrator Technology (FACT) is a lightweight, high-performance reflective concentrator blanket assembly that can be used on flexible solar array blankets. The FACT concentrator replaces every other row of solar cells on a solar array blanket, significantly reducing the cost of the array. The modular design is highly scalable for the array system designer, and exhibits compact stowage, good off-pointing acceptance, and mass/cost savings. The assembly s relatively low concentration ratio, accompanied by a large radiative area, provides for a low cell operating temperature, and eliminates many of the thermal problems inherent in high-concentration-ratio designs. Unlike other reflector technologies, the FACT concentrator modules function on both z-fold and rolled flexible solar array blankets, as well as rigid array systems. Mega-ROSA (Mega Roll-Out Solar Array) is a new, highly modularized and extremely scalable version of ROSA that provides immense power level range capability from 100 kW to several MW in size. Mega-ROSA will enable extremely high-power spacecraft and SEP-powered missions, including space-tug and largescale planetary science and lunar/asteroid exploration missions. Mega-ROSA's inherent broad power scalability is achieved while retaining ROSA s solar array performance metrics and missionenabling features for lightweight, compact stowage volume and affordability. This innovation will enable future ultra-high-power missions through lowcost (25 to 50% cost savings, depending on PV and blanket technology), lightweight, high specific power (greater than 200 to 400 Watts per kilogram BOL (beginning-of-life) at the wing level depending on PV and blanket technology), compact stowage volume (greater than 50 kilowatts per cubic meter for very large arrays), high reliability, platform simplicity (low failure modes), high deployed strength/stiffness when scaled to huge sizes, and high-voltage operation capability. Mega-ROSA is adaptable to all photovoltaic and concentrator flexible blanket technologies, and can readily accommodate standard multijunction and emerging ultra-lightweight IMM (inverted metamorphic) photovoltaic flexible blanket assemblies, as well as ENTECHs Stretched Lens Array (SLA) and DSSs (Deployable Space Systems) FACT, which allows for cost reduction at the array level.

Special issue on compact x-ray sources

NASA Astrophysics Data System (ADS)

Hooker, Simon; Midorikawa, Katsumi; Rosenzweig, James

2014-04-01

Journal of Physics B: Atomic, Molecular and Optical Physics is delighted to announce a forthcoming special issue on compact x-ray sources, to appear in the winter of 2014, and invites you to submit a paper. The potential for high-brilliance x- and gamma-ray sources driven by advanced, compact accelerators has gained increasing attention in recent years. These novel sources—sometimes dubbed 'fifth generation sources'—will build on the revolutionary advance of the x-ray free-electron laser (FEL). New radiation sources of this type have widespread applications, including in ultra-fast imaging, diagnostic and therapeutic medicine, and studies of matter under extreme conditions. Rapid advances in compact accelerators and in FEL techniques make this an opportune moment to consider the opportunities which could be realized by bringing these two fields together. Further, the successful development of compact radiation sources driven by compact accelerators will be a significant milestone on the road to the development of high-gradient colliders able to operate at the frontiers of particle physics. Thus the time is right to publish a peer-reviewed collection of contributions concerning the state-of-the-art in: advanced and novel acceleration techniques; sophisticated physics at the frontier of FELs; and the underlying and enabling techniques of high brightness electron beam physics. Interdisciplinary research connecting two or more of these fields is also increasingly represented, as exemplified by entirely new concepts such as plasma based electron beam sources, and coherent imaging with fs-class electron beams. We hope that in producing this special edition of Journal of Physics B: Atomic, Molecular and Optical Physics (iopscience.iop.org/0953-4075/) we may help further a challenging mission and ongoing intellectual adventure: the harnessing of newly emergent, compact advanced accelerators to the creation of new, agile light sources with unprecedented capabilities. New schemes for compact accelerators: laser- and beam-driven plasma accelerators; dielectric laser accelerators; THz accelerators. Latest results for compact accelerators. Target design and staging of advanced accelerators. Advanced injection and phase space manipulation techniques. Novel diagnostics: single-shot measurement of sub-fs bunch duration; measurement of ultra-low emittance. Generation and characterization of incoherent radiation: betatron and undulator radiation; Thomson/Compton scattering sources, novel THz sources. Generation and characterization of coherent radiation. Novel FEL simulation techniques. Advances in simulations of novel accelerators: simulations of injection and acceleration processes; simulations of coherent and incoherent radiation sources; start-to-end simulations of fifth generation light sources. Novel undulator schemes. Novel laser drivers for laser-driven accelerators: high-repetition rate laser systems; high wall-plug efficiency systems. Applications of compact accelerators: imaging; radiography; medical applications; electron diffraction and microscopy. Please submit your article by 15 May 2014 (expected web publication: winter 2014); submissions received after this date will be considered for the journal, but may not be included in the special issue.

Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

NASA Astrophysics Data System (ADS)

Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

2017-11-01

One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

Mu-Spec - A High Performance Ultra-Compact Photon Counting spectrometer for Space Submillimeter Astronomy

NASA Technical Reports Server (NTRS)

Moseley, H.; Hsieh, W.-T.; Stevenson, T.; Wollack, E.; Brown, A.; Benford, D.; Sadleir; U-Yen, I.; Ehsan, N.; Zmuidzinas, J.;

Characterization of a High-SpeedHigh-Power Semiconductor Master-Oscillator Power-Amplifier (MOPA) Laser as a Free-Space Transmitter

NASA Astrophysics Data System (ADS)

Wright, M. W.

2000-04-01

Semiconductor lasers offer promise as high-speed transmitters for free-space optical communication systems. This article examines the performance of a semiconductor laser system in a master-oscillator power-amplifier (MOPA) geometry developed through a Small Business Innovation Research (SBIR) contract with SDL, Inc. The compact thermo-electric cooler (TEC) packaged device is capable of 1-W output optical power at greater than 2-Gb/s data rates and a wavelength of 960 nm. In particular, we have investigated the effects of amplified spontaneous emission on the modulation extinction ratio and bit-error rate (BER) performance. BERs of up to 10^(-9) were possible at 1.4 Gb/s; however, the modulation extinction ratio was limited to 6 dB. Other key parameters for a free-space optical transmitter, such as the electrical-optical efficiency (24 percent) and beam quality, also were measured.

Environmental Assessment: PL 84-99 Levee Rahabilitation Program Lower Platte South Natural Resource District Salt Creek, Lincoln, Lancaster County, Nebraska

DTIC Science & Technology

2015-03-01

lost bank material with compacted, non-dispersive clay and riprap; constructing landward piggy-back levees at discrete locations if space is available...consist of approximately seven miles of levees. The levees have 3:1 side slopes that are made up of clay soil, with a two-foot minimum freeboard. The...reshaping the levee and replacing lost bank material with compacted, non-dispersive clay and riprap or building a landside piggy back levee if space is

Subleading soft theorem for multiple soft gravitons

NASA Astrophysics Data System (ADS)

Chakrabarti, Subhroneel; Kashyap, Sitender Pratap; Sahoo, Biswajit; Sen, Ashoke; Verma, Mritunjay

2017-12-01

We derive the subleading soft graviton theorem in a generic quantum theory of gravity for arbitrary number of soft external gravitons and arbitrary number of finite energy external states carrying arbitrary mass and spin. Our results are valid to all orders in perturbation theory when the number of non-compact space-time dimensions is six or more, but only for tree amplitudes for five or less non-compact space-time dimensions due to enhanced contribution to loop amplitudes from the infrared region.

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

Blaut, Arkadiusz

We present the results of the estimation of parameters with LISA for nearly monochromatic gravitational waves in the low and high frequency regimes for the time-delay interferometry response. Angular resolution of the detector and the estimation errors of the signal's parameters in the high frequency regimes are calculated as functions of the position in the sky and as functions of the frequency. For the long-wavelength domain we give compact formulas for the estimation errors valid on a wide range of the parameter space.

A Novel Porosity Model for Use in Hydrocode Simulations

NASA Technical Reports Server (NTRS)

Wuennemann, K.; Collins, G. S.; Melosh, H. J.

2005-01-01

Introduction: Numerical modeling of impact cratering has reached a high degree of sophistication; however, the treatment of porous materials still poses a large problem in hydrocode calculations. Porosity plays only a minor role in the formation of large craters on most planetary objects, but impacts on comets are believed to be highly affected by the presence of porosity, which may be as much as 80%. The upcoming Deep Impact Mission (launched January 2005) will provide more detailed data about the composition of a comet (Tempel 1) by shooting a approx.370 kg projectile onto the surface of its nucleus. The numerical simulations of such impact events requires an appropriate model for how pore space in the comet is crushed out during the violent initial stage of the impact event. Most hydro-codes compute the pressure explicitly using an "equation of state" (EOS) for each material, which relates changes in density and internal energy to changes in pressure. The added complication introduced by porosity is that changes in a material s density are due to both the closing of pore space (compaction) and compression of the matrix. The amount of resistance to volume change and the amount of irreversible work done during these two processes is very different; it is far easier to compact a porous material sample than to compress a non-porous sample of the same material. As an alternative to existing porosity models, like the Pdot(alpha) model [1], we present a novel approach for dealing with the compaction of porosity in hydrocode calculations.

LISA: Astrophysics Out to z Approximately 10 with Low-Frequency Gravitational Waves

NASA Technical Reports Server (NTRS)

Stebbins, Robin T.

2008-01-01

This viewgraph presentation reviews the Laser Interferometer Space Antenna (LISA). LISA os a joint ESA-NASA project to design, build and operate a space-based gravitational wave detector. The 5 million Kilometer long detector will consist of three spacecraft orbiting the Sun in a triangular formation. Space-Time strains induced by gravitational waves are detected by measuring changes in the separation of fiducial masses with laser interferometry. LISA is expected to detect signals from merging massive black holes, compact stellar objects spiraling into super massive black holes in galactic nuclei, thousands of close binaries of compact objects in the Milky way and possible backgrounds of cosmological origin.

A Roadmap to Fundamental Physics from LISA EMRI Observations

NASA Astrophysics Data System (ADS)

Sopuerta, Carlos F.

2010-09-01

The Laser Interferometer Space Antenna is a future space-based gravitational-wave observatory (a joint mission between the European Space Agency and the US National Aeronautics and Space Administration) that is expected to be launched during the next decade. It will operate in the low-frequency gravitational-wave band, probably the richest part of the gravitational-wave spectrum in terms of science potential, where we find: massive black hole mergers as the outcome of galaxy collisions; many galactic compact binaries; the capture and subsequent inspiral of a stellar compact object into a massive black hole; and gravitational-wave signatures from early universe physical processes connected to high-energy physics and physics not yet fully understood. In this article we focus on the third type of source, the so-called extreme-mass-ratio inspirals, a high precision tool for gravitational wave astronomy that can be used, among other things, to advance in our understanding of fundamental physics questions like the nature and structure of black holes and the details of the gravitational interaction in regimes not yet proven by other experiments/observatories. Here, we give an account of some of the progress made in the development of tools to exploit the future LISA EMRI observations, we discuss what scientific questions we can try to answer from this information and, finally, we discuss the main theoretical challenges that we face in order to develop all the necessary tools to maximize the scientific outcome and some avenues that can be followed to make progress in the near future.

Evaluating the methodology and performance of jetting and flooding of granular backfill materials.

DOT National Transportation Integrated Search

2014-11-01

Compaction of backfill in confined spaces on highway projects is often performed with small vibratory plates, based : solely on the experience of the contractor, leading to inadequate compaction. As a result, the backfill is prone to : erosion and of...

Design and progress report for compact cryocooled sapphire oscillator 'VCSO'

NASA Technical Reports Server (NTRS)

Dick, G. John; Wang, Rabi T.; Tjoelker, Robert L.

2005-01-01

We report on the development of a compact cryocooled sapphiere oscillator 'VCSO', designed as a higher-performance replacement for ultra-stable quartz oscillators in local oscillator, cleanup, and flywheel applications in the frequency generation and distribution subsystems of NASA's Deep Space Network (DSN).

Quantitative analyses of the 3D nuclear landscape recorded with super-resolved fluorescence microscopy.

PubMed

Schmid, Volker J; Cremer, Marion; Cremer, Thomas

2017-07-01

Recent advancements of super-resolved fluorescence microscopy have revolutionized microscopic studies of cells, including the exceedingly complex structural organization of cell nuclei in space and time. In this paper we describe and discuss tools for (semi-) automated, quantitative 3D analyses of the spatial nuclear organization. These tools allow the quantitative assessment of highly resolved different chromatin compaction levels in individual cell nuclei, which reflect functionally different regions or sub-compartments of the 3D nuclear landscape, and measurements of absolute distances between sites of different chromatin compaction. In addition, these tools allow 3D mapping of specific DNA/RNA sequences and nuclear proteins relative to the 3D chromatin compaction maps and comparisons of multiple cell nuclei. The tools are available in the free and open source R packages nucim and bioimagetools. We discuss the use of masks for the segmentation of nuclei and the use of DNA stains, such as DAPI, as a proxy for local differences in chromatin compaction. We further discuss the limitations of 3D maps of the nuclear landscape as well as problems of the biological interpretation of such data. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental demonstration of subwavelength domino plasmon devices for compact high-frequency circuit.

PubMed

Ma, Y G; Lan, L; Zhong, S M; Ong, C K

2011-10-24

In optical frequency, surface plasmons of metal provide us a prominent way to build compact photonic devices or circuits with non-diffraction limit. It is attributed by their extraordinary electromagnetic confining effect. But in the counterpart of lower frequencies, plasmonics behavior of metal is screened by eddy current induced in a certain skin depth. To amend this, spoof plasmons engineered by artificial structures have been introduced to mimic surface plasmons in these frequencies. But it is less useful for practical application due to their weak field confinement as manifested by large field decaying length in the upper dielectric space. Recently, a new type of engineered plasmons, domino plasmon was theoretically proposed to produce unusual field confinement and waveguiding capabilities that make them very attractive for ultra-compact device applications [Opt. Exp. 18, 754-764 (2010)]. In this work, we implemented these ideas and built three waveguiding devices based on domino plasmons. Their strong capabilities to produce versatile and ultra-compact devices with multiple electromagnetic functions have been experimentally verified in microwaves. And that can be extended to THz regime to pave the way for a new class of integrated wave circuits. © 2011 Optical Society of America

HST images of very compact blue galaxies at z approximately 0.2

NASA Technical Reports Server (NTRS)

Koo, David C.; Bershady, Matthew A.; Wirth, Gregory D.; Stanford, S. Adam; Majewski, Steven R.

1994-01-01

We present the results of Hubble Space Telescope (HST) Wide-Field Camera (WFC) imaging of seven very compact, very blue galaxies with B less than or equal to 21 and redshifts z approximately 0.1 to 0.35. Based on deconvolved images, we estimate typical half-light diameters of approximately 0.65 sec, corresponding to approximately 1.4 h(exp -1) kpc at redshifts z approximately 0.2. The average rest frame surface brightness within this diameter is mu(sub v) approximately 20.5 mag arcsec(exp -2), approximately 1 mag brighter than that of typical late-type blue galaxies. Ground-based spectra show strong, narrow emission lines indicating high ionization; their very blue colors suggest recent bursts of star-formation; their typical luminosities are approximately 4 times fainter than that of field galaxies. These characteristics suggest H II galaxies as likely local counterparts of our sample, though our most luminous targets appear to be unusually compact for their luminosities.

An alternative cooling system to enhance the safety of Li-ion battery packs

NASA Astrophysics Data System (ADS)

Kizilel, Riza; Sabbah, Rami; Selman, J. Robert; Al-Hallaj, Said

A passive thermal management system is evaluated for high-power Li-ion packs under stressful or abusive conditions, and compared with a purely air-cooling mode under normal and abuse conditions. A compact and properly designed passive thermal management system utilizing phase change material (PCM) provides faster heat dissipation than active cooling during high pulse power discharges while preserving sufficiently uniform cell temperature to ensure the desirable cycle life for the pack. This study investigates how passive cooling with PCM contributes to preventing the propagation of thermal runaway in a single cell or adjacent cells due to a cell catastrophic failure. Its effectiveness is compared with that of active cooling by forced air flow or natural convection using the same compact module and pack configuration corresponding to the PCM matrix technology. The effects of nickel tabs and spacing between the cells were also studied.

High performance optical payloads for microsatellites

NASA Astrophysics Data System (ADS)

Geyl, Roland; Rodolfo, Jacques; Girault, Jean-Philippe

2017-09-01

Safran is presenting two concepts of optical payloads for microsatellites combining high performances and extremely compact volume. The first one offer 10-m Ground Sampling Distance (GSD) over 60x40 km2 area from 600 km orbit optimized for twilight conditions. The second one is offering a much higher resolution of 1.8-m over 11x7,5 km2 area from the same 600 km orbit. The two concepts are based on advanced innovative diffraction limited optical system packaged in a unique very compact volume lower than 8U = 200x200x200 mm making them the ideal solution for 15- 100 kg microsatellites. The maximum number of pixels is served to the end-user space imagery community thanks to 35 mm Full Frame sensors offering, as of today, 6000x4000 pixels. Up to 10 spectral bands from 475 to 900 nm can be offered thanks to 2D structured filters.

A compact acousto-optic lens for 2D and 3D femtosecond based 2-photon microscopy

PubMed Central

Kirkby, Paul A.; Naga Srinivas, N.K.M.; Silver, R. Angus

2010-01-01

We describe a high speed 3D Acousto-Optic Lens Microscope (AOLM) for femtosecond 2-photon imaging. By optimizing the design of the 4 AO Deflectors (AODs) and by deriving new control algorithms, we have developed a compact spherical AOL with a low temporal dispersion that enables 2-photon imaging at 10-fold lower power than previously reported. We show that the AOLM can perform high speed 2D raster-scan imaging (>150 Hz) without scan rate dependent astigmatism. It can deflect and focus a laser beam in a 3D random access sequence at 30 kHz and has an extended focusing range (>137 μm; 40X 0.8NA objective). These features are likely to make the AOLM a useful tool for studying fast physiological processes distributed in 3D space PMID:20588506

Compact and Rugged Transceiver for Coherent Doppler Wind Lidar Applications in Space

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Koch, Grady J.; Yu, Jirong; Amzajerdian, Farzin; Singh, Upendra N.; Trieu, Bo C.; Modlin, Ed A.; Petros, Mulugeta; Bai, Yingxin; Reithmaier, Karl;

High Energy Observational Investigations of Supernova Remnants and their Interactions with Surroundings

NASA Astrophysics Data System (ADS)

Hui, Chung-Yue

2013-09-01

Here we review the effort of Fermi Asian Network (FAN) in exploring the supernova remnants (SNRs) with state-of-art high energy observatories, including Fermi Gamma-ray Space Telescope and Chandra X-ray Observatory, in the period of 2011- 2012. Utilizing the data from Fermi LAT, we have discovered the GeV emission at the position of the Galactic SNR Kes 17 which provides evidence for the hadronic acceleration. Our study also sheds light on the propagation of cosmic rays from their acceleration site to the intersteller medium. We have also launched an identification campaign of SNR candidates in the Milky Way, in which a new SNR G308.3-1.4 have been uncovered with our Chandra observation. Apart from the remnant, we have also discovered an associated compact object at its center. The multiwavelength properties of this X-ray source suggest it can possibly be the compact binary that survived a supernova explosion.

A new design using GEM-based technology for the CMS experiment

NASA Astrophysics Data System (ADS)

Ressegotti, M.

2017-07-01

The muon system of the Compact Muon Solenoid (CMS) experiment at the LHC is currently not instrumented for pseudorapidity higher than |η|> 2.4. The main challenges to the installation of a detector in that position are the high particle flux to be sustained, a high level of radiation, and the ability to accomodate a multilevel detector into the small available space (less than 30 cm). A new back-to-back configuration of a Gas Electron Multiplier (GEM) detector is presented with the aim of developing a compact, multi-layer GEM detector. It is composed of two independent stacked triple-GEM detectors, positioned with the anodes toward the outside and sharing the same cathode plane, which is located at the center of the chamber, to reduce the total detector's thickness. A first prototype has been produced and tested with an X-Ray source and muon beam. First results on its performance are presented.

The Space Optical Clock project: status and perspectives

NASA Astrophysics Data System (ADS)

Schiller, Stephan; Tino, Guglielmo M.; Sterr, Uwe; Lemonde, Pierre; Görlitz, Axel; Salomon, Christophe

The Space Optical Clocks project aims at operating lattice clocks on the ISS for tests of funda-mental physics and for providing high-accuracy comparisons of future terrestrial optical clocks. A pre-phase-A study (2007-10), funded partially by ESA and DLR, includes the implementa-tion of several optical lattice clock systems using Strontium and Ytterbium as atomic systems and their characterization. Subcomponents of clock demonstrators with the added specification of transportability and using techniques that are suitable for later space use, such as all-solid-state lasers, low power consumption, and compact dimensions, have been developed and are being validated. The talk will give a brief overview over the achieved results and outline future developments.

STRV RADMON: An integrated high-energy particle detector

NASA Technical Reports Server (NTRS)

Buehler, Martin; Soli, George; Blaes, Brent; Tardio, Gemma

1993-01-01

The RADMON (Radiation Monitor) was developed as a compact device with a 4-kbit SRAM particle detector and two p-FET total dose monitors. Thus it can be used as a spacecraft radiation alarm and in situ total dose monitor. This paper discusses the design and calibration of the SRAM for proton, alpha, and heavy ion detection. Upset rates for the RADMON, based on a newly developed space particle flux algorithm, are shown to vary over eight orders of magnitude. On the STRV (Space Technology Research Vehicle) the RADMON's SRAM will be used to detect trapped protons, solar flares, and cosmic rays and to evaluate our ability to predict space results from ground tests.

Terahertz (THz) Wireless Systems for Space Applications

NASA Technical Reports Server (NTRS)

Hwu, Shian U.; deSilva, Kanishka B.; Jih, Cindy T.

2013-01-01

NASA has been leading the Terahertz (THz) technology development for the sensors and instruments in astronomy in the past 20 years. THz technologies are expanding into much broader applications in recent years. Due to the vast available multiple gigahertz (GHz) broad bandwidths, THz radios offer the possibility for wireless transmission of high data rates. Multi-Gigabits per second (MGbps) broadband wireless access based on THz waves are closer to reality. The THz signal high atmosphere attenuation could significantly decrease the communication ranges and transmittable data rates for the ground systems. Contrary to the THz applications on the ground, the space applications in the atmosphere free environment do not suffer the atmosphere attenuation. The manufacturing technologies for the THz electronic components are advancing and maturing. There is great potential for the NASA future high data wireless applications in environments with difficult cabling and size/weight constraints. In this study, the THz wireless systems for potential space applications were investigated. The applicability of THz systems for space applications was analyzed. The link analysis indicates that MGbps data rates are achievable with compact sized high gain antennas.

Thermionic/AMTEC cascade converter concept for high-efficiency space power

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

Hagan, T.H. van; Smith, J.N. Jr.; Schuller, M.

1996-12-31

This paper presents trade studies that address the use of the thermionic/AMTEC cell--a cascaded, high-efficiency, static power conversion concept that appears well-suited to space power applications. Both the thermionic and AMTEC power conversion approaches have been shown to be promising candidates for space power. Thermionics offers system compactness via modest efficiency at high heat rejection temperatures, and AMTEC offers high efficiency at modest heat rejection temperature. From a thermal viewpoint the two are ideally suited for cascaded power conversion: thermionic heat rejection and AMTEC heat source temperatures are essentially the same. In addition to realizing conversion efficiencies potentially as highmore » as 35--40%, such a cascade offers the following perceived benefits: survivability; simplicity; technology readiness; and technology growth. Mechanical approaches and thermal/electric matching criteria for integrating thermionics and AMTEC into a single conversion device are described. Focusing primarily on solar thermal space power applications, parametric trends are presented to show the performance and cost potential that should be achievable with present-day technology in cascaded thermionic/AMTEC systems.« less

Black branes and black strings in the astrophysical and cosmological context

NASA Astrophysics Data System (ADS)

Akarsu, Özgür; Chopovsky, Alexey; Zhuk, Alexander

2018-03-01

We consider Kaluza-Klein models where internal spaces are compact flat or curved Einstein spaces. This background is perturbed by a compact gravitating body with the dust-like equation of state (EoS) in the external/our space and an arbitrary EoS parameter Ω in the internal space. Without imposing any restrictions on the form of the perturbed metric and the distribution of the perturbed energy densities, we perform the general analysis of the Einstein and conservation equations in the weak-field limit. All conclusions follow from this analysis. For example, we demonstrate that the perturbed model is static and perturbed metric preserves the block-diagonal form. In a particular case Ω = - 1 / 2, the found solution corresponds to the weak-field limit of the black strings/branes. The black strings/branes are compact gravitating objects which have the topology (four-dimensional Schwarzschild spacetime) × (d-dimensional internal space) with d ≥ 1. We present the arguments in favour of these objects. First, they satisfy the gravitational tests for the parameterized post-Newtonian parameter γ at the same level of accuracy as General Relativity. Second, they are preferable from the thermodynamical point of view. Third, averaging over the Universe, they do not destroy the stabilization of the internal space. These are the astrophysical and cosmological aspects of the black strings/branes.

Orbital stability of compact three-planets systems.

NASA Astrophysics Data System (ADS)

Gavino, Sacha; Lissauer, Jack

2018-04-01

Recent discoveries unveiled a significant number of compact multi-planetary systems, where the adjacent planets orbits are much closer to those found in the Solar System. Studying the orbital stability of such compact systems provides information on how they form and how long they survive. We performed a general study of three Earth-like planets orbiting a Sun-mass star in circular and coplanar prograde orbits. The simulations were performed over a wide range of mutual Hill radii and were conducted for virtual times reaching at most 10 billion years. Both equally-spaced and unequally spaced planet systems are investigated. We recover the results of previous studies done for systems of planets spaced uniformly in mutual Hill radius and we investigate mean motion resonances and test chaos. We also study systems with different initial spacing between the adjacent inner pair of planets and the outer pair of planets and we displayed their lifetime on a grid at different resolution. Over 45000 simulations have been done. We then characterize isochrones for lifetime of systems of equivalent spacing. We find that the stability time increases significantly for values of mutual Hill radii beyond 8. We also study the affects of mean motion resonances, the degree of symmetry in the grid and test chaos.

Low energy CMOS for space applications

NASA Technical Reports Server (NTRS)

Panwar, Ramesh; Alkalaj, Leon

1992-01-01

The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

On τ-Compactness of Products of τ-Measurable Operators

NASA Astrophysics Data System (ADS)

Bikchentaev, Airat M.

2017-12-01

Let M be a von Neumann algebra of operators on a Hilbert space H, τ be a faithful normal semifinite trace on M. We obtain some new inequalities for rearrangements of τ-measurable operators products. We also establish some sufficient τ-compactness conditions for products of selfadjoint τ-measurable operators. Next we obtain a τ-compactness criterion for product of a nonnegative τ-measurable operator with an arbitrary τ-measurable operator. We construct an example that shows importance of nonnegativity for one of the factors. The similar results are obtained also for elementary operators from M. We apply our results to symmetric spaces on (M, τ ). The results are new even for the *-algebra B(H) of all linear bounded operators on H endowed with the canonical trace τ = tr.

Demonstration of Subscale Cermet Fuel Specimen Fabrication Approach Using Spark Plasma Sintering and Diffusion Bonding

NASA Technical Reports Server (NTRS)

Barnes, Marvin W.; Tucker, Dennis S.; Benensky, Kelsa M.

2018-01-01

Nuclear thermal propulsion (NTP) has the potential to expand the limits of human space exploration by enabling crewed missions to Mars and beyond. The viability of NTP hinges on the development of a robust nuclear fuel material that can perform in the harsh operating environment (> or = 2500K, reactive hydrogen) of a nuclear thermal rocket (NTR) engine. Efforts are ongoing to develop fuel material and to assemble fuel elements that will be stable during the service life of an NTR. Ceramic-metal (cermet) fuels are being actively pursued by NASA Marshall Space Flight Center (MSFC) due to their demonstrated high-temperature stability and hydrogen compatibility. Building on past cermet fuel development research, experiments were conducted to investigate a modern fabrication approach for cermet fuel elements. The experiments used consolidated tungsten (W)-60vol%zirconia (ZrO2) compacts that were formed via spark plasma sintering (SPS). The consolidated compacts were stacked and diffusion bonded to assess the integrity of the bond lines and internal cooling channel cladding. The assessment included hot hydrogen testing of the manufactured surrogate fuel and pure W for 45 minutes at 2500 K in the compact fuel element environmental test (CFEET) system. Performance of bonded W-ZrO2 rods was compared to bonded pure W rods to access bond line integrity and composite stability. Bonded surrogate fuels retained structural integrity throughout testing and incurred minimal mass loss.

Scintillating Fiber Technology for a High Neutron Spectrometer

NASA Technical Reports Server (NTRS)

Kuznetsov, Evgeny; Adams, James, Jr.; Christl, Mark; Norwood, Joseph; Watts, John

2014-01-01

Develop a compact low-power neutron spectrometer that uniquely identifies neutrons in the mixed radiation field expected on crewed deep-space missions. Secondary neutrons are generated by cosmic rays striking heavy crewed spacecraft as well as lunar and planetary surfaces1,2. It has been shown that secondary neutrons can account for up to 50% if the total dose-equivalent received by the crew.

Picometre and nanoradian heterodyne interferometry and its application in dilatometry and surface metrology

NASA Astrophysics Data System (ADS)

Schuldt, T.; Gohlke, M.; Kögel, H.; Spannagel, R.; Peters, A.; Johann, U.; Weise, D.; Braxmaier, C.

2012-05-01

A high-sensitivity heterodyne interferometer implementing differential wavefront sensing for tilt measurement was developed over the last few years. With this setup, using an aluminium breadboard and compact optical mounts with a beam height of 2 cm, noise levels less than 5 pm Hz-1/2 in translation and less than 10 nrad Hz-1/2 in tilt measurement, both for frequencies above 10-2 Hz, have been demonstrated. Here, a new, compact and ruggedized interferometer setup utilizing a baseplate made of Zerodur, a thermally and mechanically highly stable glass ceramic with a coefficient of thermal expansion (CTE) of 2 × 10-8 K-1, is presented. The optical components are fixed to the baseplate using a specifically developed, easy-to-handle, assembly-integration technology based on a space-qualified two-component epoxy. While developed as a prototype for future applications aboard satellite space missions (such as Laser Interferometer Space Antenna), the interferometer is used in laboratory experiments for dilatometry and surface metrology. A first dilatometer setup with a demonstrated accuracy of 10-7 K-1 in CTE measurement was realized. As it was seen that the accuracy is limited by the dimensional stability of the sample tube support, a new setup was developed utilizing Zerodur as structural material for the sample tube support. In another activity, the interferometer is used for characterization of high-quality mirror surfaces at the picometre level and for high-accuracy two-dimensional surface characterization in a prototype for industrial applications. In this paper, the corresponding designs, their realizations and first measurements of both applications in dilatometry and surface metrology are presented.

High-resolution mapping of yield curve shape and evolution for high porosity sandstones

NASA Astrophysics Data System (ADS)

Bedford, J. D.; Faulkner, D.; Wheeler, J.; Leclere, H.

2017-12-01

The onset of permanent inelastic deformation for porous rock is typically defined by a yield curve plotted in P-Q space, where P is the effective mean stress and Q is the differential stress. Sandstones usually have broadly elliptical shaped yield curves, with the low pressure side of the ellipse associated with localized brittle faulting (dilation) and the high pressure side with distributed ductile deformation (compaction). However recent works have shown that these curves might not be perfectly elliptical and that significant evolution in shape occurs with continued deformation. We therefore use a novel stress-probing methodology to map in high-resolution the yield curve shape for Boise and Idaho Gray sandstones (36-38% porosity) and also investigate curve evolution with increasing deformation. The data reveal yield curves with a much flatter geometry than previously recorded for porous sandstone and that the compactive side of the curve is partly comprised of a near vertical limb. The yield curve evolution is found to be strongly dependent on the nature of inelastic strain. Samples that were compacted under a deviatoric load, with a component of inelastic shear strain, were found to have yield curves with peaks that are approximately 50% higher than similar porosity samples that were hydrostatically compacted (i.e. purely volumetric strain). The difference in yield curve evolution along the different loading paths is attributed to mechanical anisotropy that develops during deviatoric loading by the closure of preferentially orientated fractures. Increased shear strain also leads to the formation of a plateau at the peak of the yield curve as samples deform along the deviatoric loading path. These results have important implications for understanding how the strength of porous rock evolves along different stress paths, including during fluid extraction from hydrocarbon reservoirs where the stress state is rarely isotropic.

High-rate wastewater treatment combining a moving bed biofilm reactor and enhanced particle separation.

PubMed

Helness, H; Melin, E; Ulgenes, Y; Järvinen, P; Rasmussen, V; Odegaard, H

2005-01-01

Many cities around the world are looking for compact wastewater treatment alternatives since space for treatment plants is becoming scarce. In this paper development of a new compact, high-rate treatment concept with results from experiments in lab-scale and pilot-scale are presented. The idea behind the treatment concept is that coagulation/floc separation may be used to separate suspended and colloidal matter (resulting in > 70% organic matter removal in normal wastewater) while a high-rate biofilm process (based on Moving Bed biofilm reactors) may be used for removing low molecular weight, easily biodegradable, soluble organic matter. By using flotation for floc/biomass separation, the total residence time for a plant according to this concept will normally be < 1 hour. A cationic polymer combined with iron is used as coagulant at low dosages (i.e. 1-2 mg polymer/l, 5-10 mg Fe/l) resulting in low sludge production (compared to conventional chemical treatment) and sufficient P-removal.

Physics evaluation of compact tokamak ignition experiments

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

Uckan, N.A.; Houlberg, W.A.; Sheffield, J.

1985-01-01

At present, several approaches for compact, high-field tokamak ignition experiments are being considered. A comprehensive method for analyzing the potential physics operating regimes and plasma performance characteristics of such ignition experiments with O-D (analytic) and 1-1/2-D (WHIST) transport models is presented. The results from both calculations are in agreement and show that there are regimes in parameter space in which a class of small (R/sub o/ approx. 1-2 m), high-field (B/sub o/ approx. 8-13 T) tokamaks with aB/sub o/S/q/sub */ approx. 25 +- 5 and kappa = b/a approx. 1.6-2.0 appears ignitable for a reasonable range of transport assumptions. Consideringmore » both the density and beta limits, an evaluation of the performance is presented for various forms of chi/sub e/ and chi/sub i/, including degradation at high power and sawtooth activity. The prospects of ohmic ignition are also examined. 16 refs., 13 figs.« less

Protecting tree roots and subterranean infrastructure in urban areas by developing self-compacting flowable fills with root growth impeding properties

NASA Astrophysics Data System (ADS)

Felde, Vincent; Simon, Jana; Kimm-Friedenberg, Stefan; Peth, Stephan; Middendorf, Bernhard

2015-04-01

In urban areas, the installation of cables and disposal lines is still done by open building method. Here, a ditch is being excavated, pipes and lines are laid and subsequently it is filled with and covered by bulk material (e.g. sand or gravel), which is then compacted. Due to the often times limited space that the roots have in the ground and the better supply of water and oxygen in the poorly compacted bulk material, these refilled ditches are areas of preferential root growth of urban trees. The entangling of the pipes and supply lines by these roots leads to severe damage of the tree when maintenance work on the lines is carried out and roots have to be cut. In order to reduce this competition between urban trees and urban subterranean infrastructure, the development of a self-compacting flowable fill with root growth resistance is mandatory. Physico-chemical properties, such as a very high pH-value and a low cation-exchange-capacity, a low root-penetrability, a high packing density and a low porosity, with a poorly connected pore system that impedes gas and water exchange are the characteristic aspects of this flowable fills that could help avoid undesired root penetration into supply lines. The flowable fills are supposed to sheath pipes and lines void-free and without any tension, in order to restrain the root growth in these areas. Trees are of crucial importance for urban ecosystems and are comprising 3% of the total stock of trees in the Federal Republic of Germany, which is why it is fundamental to conserve them. This work therefore targets not only at enabling a balanced coexistence of urban trees and subterranean infrastructure, but also at avoiding costly re-opening of ditches, tree harming cutting of roots and time consuming maintenance work. Further positive side effects are reduced costs for network providers and local municipalities, as well as reduced noise and dust emissions for passersby and local residents. To guarantee the root growth restricting properties, the self-compacting fill has to have less porosity than the adjacent soil (40 - 60%). Theoretically a porosity of 30% is possible with a homogeneous compaction of sand. In urban areas, however, because of the limited spaces and crossing pipes, a mechanical and homogenous compacting is often impossible. Porosities of 60 to 70% are the result. Self-compacting flowable fills have a porosity of about 40% while the first optimized materials can even have a porosity of 28%. We present the first results of the hydro-mechanical properties of the different materials under development that highlight the influence of the mixture of the fills (i.e. maximal grain size) on the root growth impeding properties, while still ensuring mechanical workability of the material (in spite of the low porosity, strengths less than 0.8 N mm-² must be ensured at all times).

Non-hermetic fiber optic transceivers for space applications

NASA Astrophysics Data System (ADS)

Tabbert, Chuck

2017-11-01

There is a commercial trend in high data-rate systems to place optical components in close proximity to the data source/sink. This trend forgoes the traditional module packaging approach to create compact components that are embedded near or within the package of high-performance ASICs. This approach reduces the power consumption and electro-magnetic interference (EMI) effects by reducing the length of copper interconnect signal paths. We present an overview of commercial trends and methods for fielding this technology within spacecraft.

Free-space quantum key distribution with a high generation rate potassium titanyl phosphate waveguide photon-pair source

NASA Astrophysics Data System (ADS)

Wilson, Jeffrey D.; Chaffee, Dalton W.; Wilson, Nathaniel C.; Lekki, John D.; Tokars, Roger P.; Pouch, John J.; Roberts, Tony D.; Battle, Philip R.; Floyd, Bertram; Lind, Alexander J.; Cavin, John D.; Helmick, Spencer R.

2016-09-01

A high generation rate photon-pair source using a dual element periodically-poled potassium titanyl phosphate (PP KTP) waveguide is described. The fully integrated photon-pair source consists of a 1064-nm pump diode laser, fiber-coupled to a dual element waveguide within which a pair of 1064-nm photons are up-converted to a single 532-nm photon in the first stage. In the second stage, the 532-nm photon is down-converted to an entangled photon-pair at 800 nm and 1600 nm which are fiber-coupled at the waveguide output. The photon-pair source features a high pair generation rate, a compact power-efficient package, and continuous wave (CW) or pulsed operation. This is a significant step towards the long term goal of developing sources for high-rate Quantum Key Distribution (QKD) to enable Earth-space secure communications. Characterization and test results are presented. Details and preliminary results of a laboratory free space QKD experiment with the B92 protocol are also presented.

Free-Space Quantum Key Distribution with a High Generation Rate Potassium Titanyl Phosphate Waveguide Photon-Pair Source

NASA Technical Reports Server (NTRS)

Wilson, Jeffrey D.; Chaffee, Dalton W.; Wilson, Nathaniel C.; Lekki, John D.; Tokars, Roger P.; Pouch, John J.; Roberts, Tony D.; Battle, Philip; Floyd, Bertram M.; Lind, Alexander J.;

Solar Energy Monitor In Space (SEMIS)

NASA Technical Reports Server (NTRS)

Thekaekara, M. P.

1974-01-01

Measurements made at high altitudes from aircraft have resulted in the establishment of standard values of the solar constant and extraterrestrial solar spectral irradiance. These standard values and other solar spectral curves are described. The problem of possible variations of the solar constant and solar spectrum and their influence on the earth-atmosphere system and weather related phenomena is examined. It is shown that the solar energy input parameters should be determined with considerably greater accuracy and precision than has been possible. An instrument package designed as a compact, low weight solar energy monitor in space (SEMIS) is described.

Conformal, Transparent Printed Antenna Developed for Communication and Navigation Systems

NASA Technical Reports Server (NTRS)

Lee, Richard Q.; Simons, Rainee N.

1999-01-01

Conformal, transparent printed antennas have advantages over conventional antennas in terms of space reuse and aesthetics. Because of their compactness and thin profile, these antennas can be mounted on video displays for efficient integration in communication systems such as palmtop computers, digital telephones, and flat-panel television displays. As an array of multiple elements, the antenna subsystem may save weight by reusing space (via vertical stacking) on photovoltaic arrays or on Earth-facing sensors. Also, the antenna could go unnoticed on automobile windshields or building windows, enabling satellite uplinks and downlinks or other emerging high-frequency communications.

Design of a ZVS PWM inverter for a brushless DC motor in an EMA application

NASA Technical Reports Server (NTRS)

Bell, J. Brett; Nelms, R. M.; Shepherd, Michael T.

1993-01-01

The Component Development Division of the Propulsion Laboratory at Marshall Space Flight Center (MSFC) is currently investigating the use of electromechanical actuators for use in space transportation applications such as Thrust Vector Control (TVC). These high power servomechanisms will require rugged, reliable, and compact power electronic modules capable of modulating several hundred amperes of current at up to 270 Vdc. This paper will discuss the design and implementation of a zero-voltage-switched PWM (Pulse Width Modulation) inverter which operates from a 270 Vdc source at currents up to 100 A.

High-grade, compact spectrometers for Earth observation from SmallSats

NASA Astrophysics Data System (ADS)

van der Wal, L. F.; de Goeij, B. T. G.; Jansen, R.; Oosterling, J. A. J.; Snijders, B.

2016-10-01

The market for nano- and microsatellites is developing rapidly. There is a strong focus on 2D imaging of the Earth's surface, with limited possibilities to obtain spectral information. More demanding applications, such as monitoring trace gases, aerosols or water quality still require advanced imaging instruments, which are large, heavy and expensive. In recent years TNO has investigated and developed different innovative designs to realize advanced spectrometers for space applications in a more compact and cost-effective manner. This offers multiple advantages: a compact instrument can be flown on a much smaller platform (nano- or microsatellite); a low-cost instrument opens up the possibility to fly multiple instruments in a satellite constellation, improving both global coverage and temporal sampling (e.g. to study diurnal processes); a constellation of low-cost instruments may provide added value to the larger scientific and operational satellite missions (e.g. the Copernicus Sentinel missions); and a small, lightweight spectrometer can also be mounted easily on a high-altitude UAV (offering high spatial resolution). Last but not least, a low-cost instrument may allow to break through the `cost spiral': lower cost will allow to take more risk and thus progress more quickly. This may lead to a much faster development cycle than customary for current Earth Observation instruments. To explore the potential of a constellation of low-cost instruments a consortium of Dutch partners was formed, which currently consists of Airbus Defence and Space Netherlands, ISISpace, S and T and TNO. In this paper we will illustrate this new design approach by using the most advanced design of a hyperspectral imaging spectrometer (named `Spectrolite') as an example. We will discuss the different design and manufacturing techniques that were used to realize this compact and low-cost design. Laboratory tests as well as the first preliminary results of airborne measurements with the Spectrolite breadboard will be presented and discussed. The design of Spectrolite offers the flexibility to tune its performance (spectral range, spectral resolution) to a specific application. Thus, based on the same basic system design, Spectrolite offers a range of applications to different clients. To illustrate this, we will present a mission concept to monitor NO2 concentrations over urban areas at high spatial resolution, based on a constellation of small satellites.

SpaceCube 2.0: An Advanced Hybrid Onboard Data Processor

NASA Technical Reports Server (NTRS)

Lin, Michael; Flatley, Thomas; Godfrey, John; Geist, Alessandro; Espinosa, Daniel; Petrick, David

2011-01-01

The SpaceCube 2.0 is a compact, high performance, low-power onboard processing system that takes advantage of cutting-edge hybrid (CPU/FPGA/DSP) processing elements. The SpaceCube 2.0 design concept includes two commercial Virtex-5 field-programmable gate array (FPGA) parts protected by gradiation hardened by software" technology, and possesses exceptional size, weight, and power characteristics [5x5x7 in., 3.5 lb (approximately equal to 12.7 x 12.7 x 17.8 cm, 1.6 kg) 5-25 W, depending on the application fs required clock rate]. The two Virtex-5 FPGA parts are implemented in a unique back-toback configuration to maximize data transfer and computing performance. Draft computing power specifications for the SpaceCube 2.0 unit include four PowerPC 440s (1100 DMIPS each), 500+ DSP48Es (2x580 GMACS), 100+ LVDS high-speed serial I/Os (1.25 Gbps each), and 2x190 GFLOPS single-precision (65 GFLOPS double-precision) floating point performance. The SpaceCube 2.0 includes PROM memory for CPU boot, health and safety, and basic command and telemetry functionality; RAM memory for program execution; and FLASH/EEPROM memory to store algorithms and application code for the CPU, FPGA, and DSP processing elements. Program execution can be reconfigured in real time and algorithms can be updated, modified, and/or replaced at any point during the mission. Gigabit Ethernet, Spacewire, SATA and highspeed LVDS serial/parallel I/O channels are available for instrument/sensor data ingest, and mission-unique instrument interfaces can be accommodated using a compact PCI (cPCI) expansion card interface. The SpaceCube 2.0 can be utilized in NASA Earth Science, Helio/Astrophysics and Exploration missions, and Department of Defense satellites for onboard data processing. It can also be used in commercial communication and mapping satellites.

Parameter Estimation for Compact Binaries with Ground-Based Gravitational-Wave Observations Using the LALInference

NASA Technical Reports Server (NTRS)

Veitch, J.; Raymond, V.; Farr, B.; Farr, W.; Graff, P.; Vitale, S.; Aylott, B.; Blackburn, K.; Christensen, N.; Coughlin, M.

2015-01-01

The Advanced LIGO and Advanced Virgo gravitational wave (GW) detectors will begin operation in the coming years, with compact binary coalescence events a likely source for the first detections. The gravitational waveforms emitted directly encode information about the sources, including the masses and spins of the compact objects. Recovering the physical parameters of the sources from the GW observations is a key analysis task. This work describes the LALInference software library for Bayesian parameter estimation of compact binary signals, which builds on several previous methods to provide a well-tested toolkit which has already been used for several studies. We show that our implementation is able to correctly recover the parameters of compact binary signals from simulated data from the advanced GW detectors. We demonstrate this with a detailed comparison on three compact binary systems: a binary neutron star (BNS), a neutron star - black hole binary (NSBH) and a binary black hole (BBH), where we show a cross-comparison of results obtained using three independent sampling algorithms. These systems were analysed with non-spinning, aligned spin and generic spin configurations respectively, showing that consistent results can be obtained even with the full 15-dimensional parameter space of the generic spin configurations. We also demonstrate statistically that the Bayesian credible intervals we recover correspond to frequentist confidence intervals under correct prior assumptions by analysing a set of 100 signals drawn from the prior. We discuss the computational cost of these algorithms, and describe the general and problem-specific sampling techniques we have used to improve the efficiency of sampling the compact binary coalescence (CBC) parameter space.

Compactly supported linearised observables in single-field inflation

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

Fröob, Markus B.; Higuchi, Atsushi; Hack, Thomas-Paul, E-mail: mbf503@york.ac.uk, E-mail: thomas-paul.hack@itp.uni-leipzig.de, E-mail: atsushi.higuchi@york.ac.uk

We investigate the gauge-invariant observables constructed by smearing the graviton and inflaton fields by compactly supported tensors at linear order in general single-field inflation. These observables correspond to gauge-invariant quantities that can be measured locally. In particular, we show that these observables are equivalent to (smeared) local gauge-invariant observables such as the linearised Weyl tensor, which have better infrared properties than the graviton and inflaton fields. Special cases include the equivalence between the compactly supported gauge-invariant graviton observable and the smeared linearised Weyl tensor in Minkowski and de Sitter spaces. Our results indicate that the infrared divergences in the tensormore » and scalar perturbations in single-field inflation have the same status as in de Sitter space and are both a gauge artefact, in a certain technical sense, at tree level.« less

Space-Charge Simulation of Integrable Rapid Cycling Synchrotron

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

Eldred, Jeffery; Valishev, Alexander

2017-05-01

Integrable optics is an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use a Synergia space-charge simulation to investigate the application of integrable optics to a high-intensity hadron ring that could replace the Fermilab Booster. We find that incorporating integrability into the design suppresses the beam halo generated by a mismatched KV beam. Our integrable rapid cycling synchrotron (iRCS) design includes other features of modern ring design such as low momentum compaction factor and harmonically canceling sextupoles. Experimental tests of high-intensity beams in integrable lattices will take place over the next several yearsmore » at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER).« less

Probabilistic modeling of anatomical variability using a low dimensional parameterization of diffeomorphisms.

PubMed

Zhang, Miaomiao; Wells, William M; Golland, Polina

2017-10-01

We present an efficient probabilistic model of anatomical variability in a linear space of initial velocities of diffeomorphic transformations and demonstrate its benefits in clinical studies of brain anatomy. To overcome the computational challenges of the high dimensional deformation-based descriptors, we develop a latent variable model for principal geodesic analysis (PGA) based on a low dimensional shape descriptor that effectively captures the intrinsic variability in a population. We define a novel shape prior that explicitly represents principal modes as a multivariate complex Gaussian distribution on the initial velocities in a bandlimited space. We demonstrate the performance of our model on a set of 3D brain MRI scans from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Our model yields a more compact representation of group variation at substantially lower computational cost than the state-of-the-art method such as tangent space PCA (TPCA) and probabilistic principal geodesic analysis (PPGA) that operate in the high dimensional image space. Copyright © 2017 Elsevier B.V. All rights reserved.

Material Usage in High Pressure Oxygen Systems for the International Space Station

NASA Technical Reports Server (NTRS)

Kravchenko, Michael; Sievers, D. Elliott

2014-01-01

The Nitrogen/Oxygen Recharge System (NORS) for the International Space Station (ISS) Program was required as part of the Space Shuttle retirement efforts to sustain the ISS life support systems. The system is designed around a 7000 psia Oxygen or Nitrogen Recharge Tank Assembly which is able to be utilized both internally and externally to the ISS. Material selection and usage were critical to ensure oxygen compatibility for the design, while taking into consideration toxicity, weldability, brazability and general fabrication and assembly techniques. The system uses unique hardware items such a composite overwrap pressure vessel (COPV), high pressure mechanical gauges, compact regulators and valves, quick disconnects, metal tubing and flexhoses. Numerous challenges and anomalies were encountered due to the exotic nature of this project which will be discussed in detail. The knowledge gained from these anomalies and failure resolutions can be applied to more than space applications, but can also be applicable to industry pressurized systems.

Blood Pressure Checker

NASA Technical Reports Server (NTRS)

1979-01-01

An estimated 30 million people in the United States have high blood pressure, or hypertension. But a great many of them are unaware of it because hypertension, in its initial stages, displays no symptoms. Thus, the simply-operated blood pressure checking devices now widely located in public places are useful health aids. The one pictured above, called -Medimax 30, is a direct spinoff from NASA technology developed to monitor astronauts in space. For manned space flights, NASA wanted a compact, highly-reliable, extremely accurate method of checking astronauts' blood pressure without the need for a physician's interpretive skill. NASA's Johnson Space Center and Technology, Inc., a contractor, developed an electronic sound processor that automatically analyzes blood flow sounds to get both systolic (contracting arteries) and diastolic (expanding arteries) blood pressure measurements. NASA granted a patent license for this technology to Advanced Life Sciences, Inc., New York City, manufacturers of Medimax 30.

The Hantzsche-Wendt manifold in cosmic topology

NASA Astrophysics Data System (ADS)

Aurich, R.; Lustig, S.

2014-08-01

The Hantzsche-Wendt space is one of the 17 multiply connected spaces of the three-dimensional Euclidean space {{{E}}^{3}}. It is a compact and orientable manifold which can serve as a model for a spatial finite universe. Since it possesses much fewer matched back-to-back circle pairs on the cosmic microwave background (CMB) sky than the other compact flat spaces, it can escape the detection by a search for matched circle pairs. The suppression of temperature correlations C(\\vartheta ) on large angular scales on the CMB sky is studied. It is shown that the large-scale correlations are of the same order as for the three-torus topology but express a much larger variability. The Hantzsche-Wendt manifold provides a topological possibility with reduced large-angle correlations that can hide from searches for matched back-to-back circle pairs.

Compact Micromachined Infrared Bandpass Filters for Planetary Spectroscopy

NASA Technical Reports Server (NTRS)

Merrell, Willie C., II; Aslam, Shahid; Brown, Ari D.; Chervenak, James A.; Huang, Wei-Chung; Quijada, Manuel; Wollack, Edward

2011-01-01

The future needs of space based observational planetary and astronomy missions include low mass and small volume radiometric instruments that can operate in high radiation and low temperature environments. Here we focus on a central spectroscopic component, the bandpass filter. We model the bandpass response of the filters to target the wavelength of the resonance peaks at 20, 40, and 60 micrometers and report good agreement between the modeled and measured response. We present a technique of using common micromachining processes for semiconductor fabrication to make compact, free standing resonant metal mesh filter arrays with silicon support frames. The process can accommodate multiple detector array architectures and the silicon frame provides lightweight mechanical support with low form factor. We also present a conceptual hybridization of the filters with a detector array.

Factor levels for density comparisons in the split-block spacing design

Treesearch

Kurt H. Riitters; Brian J. Stanton; Robbert H. Walkup

1989-01-01

The split-block spacing design is a compact test of the effects of within-row and between-row spacings. But the sometimes awkward analysis of density (i.e., trees/ha) effects may deter use of the design. The analysis is simpler if the row spacings are chosen to obtain a balanced set of equally spaced density and rectangularity treatments. A spacing study in poplar (...

NASA Tech Briefs, January 2013

NASA Technical Reports Server (NTRS)

2013-01-01

Topics include: Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector; Surface-Enhanced Raman Scattering Using Silica Whispering-Gallery Mode Resonators; 3D Hail Size Distribution Interpolation/Extrapolation Algorithm; Color-Changing Sensors for Detecting the Presence of Hypergolic Fuels; Artificial Intelligence Software for Assessing Postural Stability; Transformers: Shape-Changing Space Systems Built with Robotic Textiles; Fibrillar Adhesive for Climbing Robots; Using Pre-Melted Phase Change Material to Keep Payloads in Space Warm for Hours without Power; Development of a Centrifugal Technique for the Microbial Bioburden Analysis of Freon (CFC-11); Microwave Sinterator Freeform Additive Construction System (MS-FACS); DSP/FPGA Design for a High-Speed Programmable S-Band Space Transceiver; On-Chip Power-Combining for High-Power Schottky Diode-Based Frequency Multipliers; FPGA Vision Data Architecture; Memory Circuit Fault Simulator; Ultra-Compact Transputer-Based Controller for High-Level, Multi-Axis Coordination; Regolith Advanced Surface Systems Operations Robot Excavator; Magnetically Actuated Seal; Hybrid Electrostatic/Flextensional Mirror for Lightweight, Large-Aperture, and Cryogenic Space Telescopes; System for Contributing and Discovering Derived Mission and Science Data; Remote Viewer for Maritime Robotics Software; Stackfile Database; Reachability Maps for In Situ Operations; JPL Space Telecommunications Radio System Operating Environment; RFI-SIM: RFI Simulation Package; ION Configuration Editor; Dtest Testing Software; IMPaCT - Integration of Missions, Programs, and Core Technologies; Integrated Systems Health Management (ISHM) Toolkit; Wind-Driven Wireless Networked System of Mobile Sensors for Mars Exploration; In Situ Solid Particle Generator; Analysis of the Effects of Streamwise Lift Distribution on Sonic Boom Signature; Rad-Tolerant, Thermally Stable, High-Speed Fiber-Optic Network for Harsh Environments; Towed Subsurface Optical Communications Buoy; High-Collection-Efficiency Fluorescence Detection Cell; Ultra-Compact, Superconducting Spectrometer-on-a-Chip at Submillimeter Wavelengths; UV Resonant Raman Spectrometer with Multi-Line Laser Excitation; Medicine Delivery Device with Integrated Sterilization and Detection; Ionospheric Simulation System for Satellite Observations and Global Assimilative Model Experiments - ISOGAME; Airborne Tomographic Swath Ice Sounding Processing System; flexplan: Mission Planning System for the Lunar Reconnaissance Orbiter; Estimating Torque Imparted on Spacecraft Using Telemetry; PowderSim: Lagrangian Discrete and Mesh-Free Continuum Simulation Code for Cohesive Soils; Multiple-Frame Detection of Subpixel Targets in Thermal Image Sequences; Metric Learning to Enhance Hyperspectral Image Segmentation; Basic Operational Robotics Instructional System; Sheet Membrane Spacesuit Water Membrane Evaporator; Advanced Materials and Manufacturing for Low-Cost, High-Performance Liquid Rocket Combustion Chambers; Motor Qualification for Long-Duration Mars Missions.

Super-spinning compact objects and models of high-frequency quasi-periodic oscillations observed in Galactic microquasars

NASA Astrophysics Data System (ADS)

Kotrlová, Andrea; Török, Gabriel; Šrámková, Eva; Stuchlík, Zdeněk

2014-12-01

We have previously applied several models of high-frequency quasi-periodic oscillations (HF QPOs) to estimate the spin of the central Kerr black hole in the three Galactic microquasars, GRS 1915+105, GRO J1655-40, and XTE J1550-564. Here we explore the alternative possibility that the central compact body is a super-spinning object (or a naked singularity) with the external space-time described by Kerr geometry with a dimensionless spin parameter a ≡ cJ/GM2> 1. We calculate the relevant spin intervals for a subset of HF QPO models considered in the previous study. Our analysis indicates that for all but one of the considered models there exists at least one interval of a> 1 that is compatible with constraints given by the ranges of the central compact object mass independently estimated for the three sources. For most of the models, the inferred values of a are several times higher than the extreme Kerr black hole value a = 1. These values may be too high since the spin of superspinars is often assumed to rapidly decrease due to accretion when a ≫ 1. In this context, we conclude that only the epicyclic and the Keplerian resonance model provides estimates that are compatible with the expectation of just a small deviation from a = 1.

The NASA Advanced Space Power Systems Project

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Hoberecht, Mark A.; Bennett, William R.; Lvovich, Vadim F.; Bugga, Ratnakumar

2015-01-01

The goal of the NASA Advanced Space Power Systems Project is to develop advanced, game changing technologies that will provide future NASA space exploration missions with safe, reliable, light weight and compact power generation and energy storage systems. The development effort is focused on maturing the technologies from a technology readiness level of approximately 23 to approximately 56 as defined in the NASA Procedural Requirement 7123.1B. Currently, the project is working on two critical technology areas: High specific energy batteries, and regenerative fuel cell systems with passive fluid management. Examples of target applications for these technologies are: extending the duration of extravehicular activities (EVA) with high specific energy and energy density batteries; providing reliable, long-life power for rovers with passive fuel cell and regenerative fuel cell systems that enable reduced system complexity. Recent results from the high energy battery and regenerative fuel cell technology development efforts will be presented. The technical approach, the key performance parameters and the technical results achieved to date in each of these new elements will be included. The Advanced Space Power Systems Project is part of the Game Changing Development Program under NASAs Space Technology Mission Directorate.

Ultra-compact air-mode photonic crystal nanobeam cavity integrated with bandstop filter for refractive index sensing.

PubMed

Sun, Fujun; Fu, Zhongyuan; Wang, Chunhong; Ding, Zhaoxiang; Wang, Chao; Tian, Huiping

2017-05-20

We propose and investigate an ultra-compact air-mode photonic crystal nanobeam cavity (PCNC) with an ultra-high quality factor-to-mode volume ratio (Q/V) by quadratically tapering the lattice space of the rectangular holes from the center to both ends while other parameters remain unchanged. By using the three-dimensional finite-difference time-domain method, an optimized geometry yields a Q of 7.2×10 6 and a V∼1.095(λ/n Si ) 3 in simulations, resulting in an ultra-high Q/V ratio of about 6.5×10 6 (λ/n Si ) -3 . When the number of holes on either side is 8, the cavity possesses a high sensitivity of 252 nm/RIU (refractive index unit), a high calculated Q-factor of 1.27×10 5 , and an ultra-small effective V of ∼0.758(λ/n Si ) 3 at the fundamental resonant wavelength of 1521.74 nm. Particularly, the footprint is only about 8×0.7  μm 2 . However, inevitably our proposed PCNC has several higher-order resonant modes in the transmission spectrum, which makes the PCNC difficult to be used for multiplexed sensing. Thus, a well-designed bandstop filter with weak sidelobes and broad bandwidth based on a photonic crystal nanobeam waveguide is created to connect with the PCNC to filter out the high-order modes. Therefore, the integrated structure presented in this work is promising for building ultra-compact lab-on-chip sensor arrays with high density and parallel-multiplexing capability.

Compact fiber optic gyroscopes for platform stabilization

NASA Astrophysics Data System (ADS)

Dickson, William C.; Yee, Ting K.; Coward, James F.; McClaren, Andrew; Pechner, David A.

2013-09-01

SA Photonics has developed a family of compact Fiber Optic Gyroscopes (FOGs) for platform stabilization applications. The use of short fiber coils enables the high update rates required for stabilization applications but presents challenges to maintain high performance. We are able to match the performance of much larger FOGs by utilizing several innovative technologies. These technologies include source noise reduction to minimize Angular Random Walk (ARW), advanced digital signal processing that minimizes bias drift at high update rates, and advanced passive thermal packaging that minimizes temperature induced bias drift while not significantly affecting size, weight, or power. In addition, SA Photonics has developed unique distributed FOG packaging technologies allowing the FOG electronics and photonics to be packaged remotely from the sensor head or independent axis heads to minimize size, weight, and power at the sensing location(s). The use of these technologies has resulted in high performance, including ARW less than 0.001 deg/rt-hr and bias drift less than 0.004 deg/hr at an update rate of 10 kHz, and total packaged volume less than 30 cu. in. for a 6 degree of freedom FOG-based IMU. Specific applications include optical beam stabilization for LIDAR and LADAR, beam stabilization for long-range free-space optical communication, Optical Inertial Reference Units for HEL stabilization, and Ka band antenna pedestal pointing and stabilization. The high performance of our FOGs also enables their use in traditional navigation and positioning applications. This paper will review the technologies enabling our high-performance compact FOGs, and will provide performance test results.

The LBA Calibrator Survey of Southern Compact Extragalactic Radio Sources - LCS1

NASA Technical Reports Server (NTRS)

Petrov, Leonid; Phillips, Chris; Bertarini, Alessandra; Murphy, Tara; Sadler, Elaine M.

2011-01-01

We present a catalogue of accurate positions and correlated flux densities for 410 flat-spectrum, compact extragalactic radio sources previously detected in the Australia Telescope 20 GHz (AT20G) survey. The catalogue spans the declination range [-90deg, -40deg] and was constructed from four 24-h very long baseline interferometry (VLBI) observing sessions with the Australian Long Baseline Array at 8.3 GHz. The VLBI detection rate in these experiments is 97 per cent, the median uncertainty of the source positions is 2.6 mas and the median correlated flux density on projected baselines longer than 1000 km is 0.14 Jy. The goals of this work are (1) to provide a pool of southern sources with positions accurate to a few milliarcsec, which can be used for phase-referencing observations, geodetic VLBI and space navigation; (2) to extend the complete flux-limited sample of compact extragalactic sources to the Southern hemisphere; and (3) to investigate the parsec-scale properties of high-frequency selected sources from the AT20G survey. As a result of this VLBI campaign, the number of compact radio sources south of declination -40deg which have measured VLBI correlated flux densities and positions known to milliarcsec accuracy has increased by a factor of 3.5.

Flying on Sun Shine: Sailing in Space

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

Alhorn, Dean

2012-03-28

On January 20th, 2011, NanoSail-D successfully deployed its sail in space. It was the first solar sail vehicle to orbit the earth and the second sail ever unfurled in space. The 10m2 sail, deployment mechanism and electronics were packed into a 3U CubeSat with a volume of about 3500cc. The NanoSail-D mission had two objectives: eject a nanosatellite from a minisatellite; deploy its sail from a highly compacted volume to validate large structure deployment and potential de-orbit technologies. NanoSail-D was jointly developed by NASA's Marshall Space Flight Center and Ames Research Center. The ManTech/NeXolve Corporation provided key sail design support.more » NanoSail-D is managed by Marshall and jointly sponsored by the Army Space and Missile Defense Command, the Space Test Program, the Von Braun Center for Science and Innovation and Dynetics Inc. The presentation will provide insights into sailcraft advances and potential missions enabled by this emerging in-space propulsion technology.« less

On the verge of an astronomy CubeSat revolution

NASA Astrophysics Data System (ADS)

Shkolnik, Evgenya L.

2018-05-01

CubeSats are small satellites built in standard sizes and form factors, which have been growing in popularity but have thus far been largely ignored within the field of astronomy. When deployed as space-based telescopes, they enable science experiments not possible with existing or planned large space missions, filling several key gaps in astronomical research. Unlike expensive and highly sought after space telescopes such as the Hubble Space Telescope, whose time must be shared among many instruments and science programs, CubeSats can monitor sources for weeks or months at time, and at wavelengths not accessible from the ground such as the ultraviolet, far-infrared and low-frequency radio. Science cases for CubeSats being developed now include a wide variety of astrophysical experiments, including exoplanets, stars, black holes and radio transients. Achieving high-impact astronomical research with CubeSats is becoming increasingly feasible with advances in technologies such as precision pointing, compact sensitive detectors and the miniaturization of propulsion systems. CubeSats may also pair with the large space- and ground-based telescopes to provide complementary data to better explain the physical processes observed.

Cryo-transmission electron microscopy of frozen-hydrated sections of Escherichia coli and Pseudomonas aeruginosa.

PubMed

Matias, Valério R F; Al-Amoudi, Ashraf; Dubochet, Jacques; Beveridge, Terry J

2003-10-01

High-pressure freezing of Escherichia coli K-12 and Pseudomonas aeruginosa PAO1 in the presence of cryoprotectants provided consistent vitrification of cells so that frozen-hydrated sections could be cut, providing approximately 2-nm resolution of structure. The size and shape of the bacteria, as well as their surface and cytoplasmic constituents, were nicely preserved and compared well with other published high-resolution techniques. Cells possessed a rich cytoplasm containing a diffuse dispersion of ribosomes and genetic material. Close examination of cells revealed that the periplasmic space was compressed during cryosectioning, a finding which provided supporting evidence that this space is filled by a compressible gel. Since the outer membrane and peptidoglycan layer are bonded together via lipoproteins, the space between them (although still part of the periplasmic space) was not as compacted. Even when this cryosectioning compression was taken into account, there was still substantial variability in the width of the periplasmic space. It is possible that the protoplast has some capacity to float freely within the periplasm.

3D shape extraction segmentation and representation of soil microstructures using generalized cylinders

NASA Astrophysics Data System (ADS)

Ngom, Ndèye Fatou; Monga, Olivier; Ould Mohamed, Mohamed Mahmoud; Garnier, Patricia

2012-02-01

This paper focuses on the modeling of soil microstructures using generalized cylinders, with a specific application to pore space. The geometric modeling of these microstructures is a recent area of study, made possible by the improved performance of computed tomography techniques. X-scanners provide very-high-resolution 3D volume images ( 3-5μm) of soil samples in which pore spaces can be extracted by thresholding. However, in most cases, the pore space defines a complex volume shape that cannot be approximated using simple analytical functions. We propose representing this shape using a compact, stable, and robust piecewise approximation by means of generalized cylinders. This intrinsic shape representation conserves its topological and geometric properties. Our algorithm includes three main processing stages. The first stage consists in describing the volume shape using a minimum number of balls included within the shape, such that their union recovers the shape skeleton. The second stage involves the optimum extraction of simply connected chains of balls. The final stage copes with the approximation of each simply optimal chain using generalized cylinders: circular generalized cylinders, tori, cylinders, and truncated cones. This technique was applied to several data sets formed by real volume computed tomography soil samples. It was possible to demonstrate that our geometric representation supplied a good approximation of the pore space. We also stress the compactness and robustness of this method with respect to any changes affecting the initial data, as well as its coherence with the intuitive notion of pores. During future studies, this geometric pore space representation will be used to simulate biological dynamics.

Testing the Binary Black Hole Nature of a Compact Binary Coalescence

NASA Astrophysics Data System (ADS)

Krishnendu, N. V.; Arun, K. G.; Mishra, Chandra Kant

2017-09-01

We propose a novel method to test the binary black hole nature of compact binaries detectable by gravitational wave (GW) interferometers and, hence, constrain the parameter space of other exotic compact objects. The spirit of the test lies in the "no-hair" conjecture for black holes where all properties of a Kerr black hole are characterized by its mass and spin. The method relies on observationally measuring the quadrupole moments of the compact binary constituents induced due to their spins. If the compact object is a Kerr black hole (BH), its quadrupole moment is expressible solely in terms of its mass and spin. Otherwise, the quadrupole moment can depend on additional parameters (such as the equation of state of the object). The higher order spin effects in phase and amplitude of a gravitational waveform, which explicitly contains the spin-induced quadrupole moments of compact objects, hence, uniquely encode the nature of the compact binary. Thus, we argue that an independent measurement of the spin-induced quadrupole moment of the compact binaries from GW observations can provide a unique way to distinguish binary BH systems from binaries consisting of exotic compact objects.

Testing the Binary Black Hole Nature of a Compact Binary Coalescence.

PubMed

Krishnendu, N V; Arun, K G; Mishra, Chandra Kant

2017-09-01

We propose a novel method to test the binary black hole nature of compact binaries detectable by gravitational wave (GW) interferometers and, hence, constrain the parameter space of other exotic compact objects. The spirit of the test lies in the "no-hair" conjecture for black holes where all properties of a Kerr black hole are characterized by its mass and spin. The method relies on observationally measuring the quadrupole moments of the compact binary constituents induced due to their spins. If the compact object is a Kerr black hole (BH), its quadrupole moment is expressible solely in terms of its mass and spin. Otherwise, the quadrupole moment can depend on additional parameters (such as the equation of state of the object). The higher order spin effects in phase and amplitude of a gravitational waveform, which explicitly contains the spin-induced quadrupole moments of compact objects, hence, uniquely encode the nature of the compact binary. Thus, we argue that an independent measurement of the spin-induced quadrupole moment of the compact binaries from GW observations can provide a unique way to distinguish binary BH systems from binaries consisting of exotic compact objects.

A compact free space quantum key distribution system capable of daylight operation

NASA Astrophysics Data System (ADS)

Benton, David M.; Gorman, Phillip M.; Tapster, Paul R.; Taylor, David M.

2010-06-01

A free space quantum key distribution system has been demonstrated. Consideration has been given to factors such as field of view and spectral width, to cut down the deleterious effect from background light levels. Suitable optical sources such as lasers and RCLEDs have been investigated as well as optimal wavelength choices, always with a view to building a compact and robust system. The implementation of background reduction measures resulted in a system capable of operating in daylight conditions. An autonomous system was left running and generating shared key material continuously for over 7 days.

The Connection Between X-ray Binaries and Star Clusters in the Antennae

NASA Astrophysics Data System (ADS)

Rangelov, Blagoy; Chandar, R.; Prestwich, A.

2011-05-01

High Mass X-ray Binaries (HMXBs) are believed to form in massive, compact star clusters. However the correlation between these young binary star systems and properties of their parent clusters are still poorly known. We compare the locations of 82 X-ray binaries detected in the merging Antennae galaxies by Zezas et al. (2006) based on observations taken with the Chandra Space Telescope, with a catalog of optically selected star clusters presented recently by Whitmore et al. (2010) based on observations taken with the Hubble Space Telescope. We find 22 X-ray binaries coincident or nearly coincident with star clusters. The ages of the clusters were estimated by comparing their UBVIHα colors with predictions from stellar evolutionary models. We find that 14 of the 22 coincident sources (64%) are hosted by star clusters with ages of 6 Myr or less. At these very young ages, only stars initially more massive than M ≥ 30 Msun have evolved into compact remnants, almost certainly black holes. Therefore, these 14 sources are likely to be black hole binaries. Five of the XRBs are hosted by young clusters with ages τ 30-50 Myr, while three are hosted by intermediate age clusters with τ 100-300 Myr. We suggest that these older X-ray binaries likely have neutron stars as the compact object. We conclude that precision age-dating of star clusters, which are spatially coincident with XRBs in nearby star forming galaxies, is a powerful method of constraining the nature of the XRBs.

Determination of an Optimal Commercial Data Bus Architecture for a Flight Data System

NASA Technical Reports Server (NTRS)

Crawford, Kevin; Johnson, Martin; Humphries, Rick (Technical Monitor)

2001-01-01

NASA/Marshall Space Flight Center (MSFC) is continually looking for methods to reduce cost and schedule while keeping the quality of work high. MSFC is NASA's lead center for space transportation and microgravity research. When supporting NASA's programs several decisions concerning the avionics system must be made. Usually many trade studies must be conducted to determine the best ways to meet the customer's requirements. When deciding the flight data system, one of the first trade studies normally conducted is the determination of the data bus architecture. The schedule, cost, reliability, and environments are some of the factors that are reviewed in the determination of the data bus architecture. Based on the studies, the data bus architecture could result in a proprietary data bus or a commercial data bus. The cost factor usually removes the proprietary data bus from consideration. The commercial data bus's range from Versa Module Eurocard (VME) to Compact PCI to STD 32 to PC 104. If cost, schedule and size are prime factors, VME is usually not considered. If the prime factors are cost, schedule, and size then Compact PCI, STD 32 and PC104 are the choices for the data bus architecture. MSFC's center director has funded a study from his discretionary fund to determine an optimal low cost commercial data bus architecture. The goal of the study is to functionally and environmentally test Compact PCI, STD 32 and PC 104 data bus architectures. This paper will summarize the results of the data bus architecture study.

Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Kavaya, Michael J.; Koch, Grady; Yu, Jirong; Ismail, Syed

2008-01-01

NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

Compact mode-locked diode laser system for high precision frequency comparisons in microgravity

NASA Astrophysics Data System (ADS)

Christopher, H.; Kovalchuk, E. V.; Wicht, A.; Erbert, G.; Tränkle, G.; Peters, A.

2017-11-01

Nowadays cold atom-based quantum sensors such as atom interferometers start leaving optical labs to put e.g. fundamental physics under test in space. One of such intriguing applications is the test of the Weak Equivalence Principle, the Universality of Free Fall (UFF), using different quantum objects such as rubidium (Rb) and potassium (K) ultra-cold quantum gases. The corresponding atom interferometers are implemented with light pulses from narrow linewidth lasers emitting near 767 nm (K) and 780 nm (Rb). To determine any relative acceleration of the K and Rb quantum ensembles during free fall, the frequency difference between the K and Rb lasers has to be measured very accurately by means of an optical frequency comb. Micro-gravity applications not only require good electro-optical characteristics but are also stringent in their demand for compactness, robustness and efficiency. For frequency comparison experiments the rather complex fiber laser-based frequency comb system may be replaced by one semiconductor laser chip and some passive components. Here we present an important step towards this direction, i.e. we report on the development of a compact mode-locked diode laser system designed to generate a highly stable frequency comb in the wavelength range of 780 nm.

Near-space flight of a correlated photon system

PubMed Central

Tang, Zhongkan; Chandrasekara, Rakhitha; Sean, Yau Yong; Cheng, Cliff; Wildfeuer, Christoph; Ling, Alexander

2014-01-01

We report the successful test flight of a device for generating and monitoring correlated photon pairs under near-space conditions up to 35.5 km altitude. Data from ground based qualification tests and the high altitude experiment demonstrate that the device continues to operate even under harsh environmental conditions. The design of the rugged, compact and power-efficient photon pair system is presented. This design enables autonomous photon pair systems to be deployed on low-resource platforms such as nanosatellites hosting remote nodes of a quantum key distribution network. These results pave the way for tests of entangled photon technology in low earth orbit. PMID:25219935

Spontaneous breaking of discrete symmetries in QCD on a small volume

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

Lucini, B.; Patella, A.; Pica, C.

2007-11-20

In a compact space with non-trivial cycles, for sufficiently small values of the compact dimensions, charge conjugation (C), spatial reflection (P) and time reversal (J) are spontaneously broken in QCD. The order parameter for the symmetry breaking is the trace of the Wilson line wrapping around the compact dimension, which acquires an imaginary part in the broken phase. We show that a physical signature for the symmetry breaking is a persistent baryonic current wrapping in the compact directions. The existence of such a current is derived analytically at first order in perturbation theory and confirmed in the non-perturbative regime bymore » lattice simulations.« less

METHOD FOR SOLVENT-ISOSTATIC PRESSING

DOEpatents

Archibald, P.B.

1962-09-18

This invention provides a method for producing densely compacted bodies having relatively large dimensions. The method comprises the addition of a small quantity of a suitable solvent to a powder which is to be compacted. The solvent- moistened powder is placed inside a flexible bag, and the bag is suspended in an isostatic press. The solvent is squeezed out of the powder by the isostatic pressure, and the resulting compacted body is recovered. The presence of the solvent markedly decreases the proportion of void space in the powder, thereby resulting in a denser, more homogeneous compact. Another effect of the solvent is that it allows the isostatic pressing operation to be conducted at substantially lower pressures than are conventionally employed. (AEC)

A phase-stepped point diffraction interferometer using liquid crystals

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Creath, Katherine; Rashidnia, Nasser

1995-01-01

A new instrument, the liquid crystal point diffraction interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with high data density and with automated data reduction. The design of the LCPDI is briefly discussed. An algorithm is presented for eliminating phase measurement error caused by object beam intensity variation from frame-to-frame. The LCPDI is demonstrated by measuring the temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to independently measured results and show excellent agreement with them. It is expected that this instrument will have application in the fluid sciences as a diagnostic tool, particularly in space based applications where autonomy, robustness, and compactness are desirable qualities. It should also be useful for the testing of optical elements, provided a master is available for comparison.

A compact high-definition low-cost digital stereoscopic video camera for rapid robotic surgery development.

PubMed

Carlson, Jay; Kowalczuk, Jędrzej; Psota, Eric; Pérez, Lance C

2012-01-01

Robotic surgical platforms require vision feedback systems, which often consist of low-resolution, expensive, single-imager analog cameras. These systems are retooled for 3D display by simply doubling the cameras and outboard control units. Here, a fully-integrated digital stereoscopic video camera employing high-definition sensors and a class-compliant USB video interface is presented. This system can be used with low-cost PC hardware and consumer-level 3D displays for tele-medical surgical applications including military medical support, disaster relief, and space exploration.

RF Manipulation and Detection of Protons in the High Performance Antiproton Trap (HiPAT)

NASA Technical Reports Server (NTRS)

Martin, James J.; Lewis, Raymond A.; Pearson, J. Boise; Sims, W. Herb; Chakrabarti, Suman; Fant, Wallace E.; McDonald, Stan

2003-01-01

The significant energy density of matter-antimatter annihilation is attractive to the designers of future space propulsion systems, with the potential to offer a highly compact source of power. Many propulsion concepts exist that could take advantage of matter-antimatter reactions, and current antiproton production rates are sufficient to support basic proof-of-principle evaluation of technology associated with antimatter-derived propulsion. One enabling technology for such experiments is portable storage of low energy antiprotons, allowing antiprotons to be trapped, stored, and transported for use at an experimental facility.

270V Battery Using COTS NiCd Cells For Manned Spacecraft

NASA Technical Reports Server (NTRS)

Darcy, Eric; Davies,Frank; Hummer, Leigh; Strangways, Brad

2002-01-01

A high power (>35 kW at 215V), low capacity (5.2 Ah), and compact (45L) NiCd battery was developed for the X-38 Crew Return Vehicle (CRV), which is an experimental version of the lifeboat for the International Space Station (ISS). A simple design and innovative approach using a commercial-off-the-shelf (COTS) NiCd cell design enabled the design, qualification, and production of 4 flight units of this highly reliable and safe spacecraft battery to be achieved rapidly (2 years) and cheaply ($13M).

Recent cryocooler progress in Japan

NASA Technical Reports Server (NTRS)

Matsubara, Y.

1985-01-01

The progress of cryocoolers and related devices in Japan is reviewed. The Japanese National Railways has developed the light weight 4 K on-board refrigerators since 1977 as part of the MAGLEV train program. Superconducting and cryogenic fundamental technology was examined which included high performance cryocooler, magnetic refrigerator and superfluid refrigeration. Space cryogenics such as the cooling systems of IR-detectors was studied. Cryocooler for special applications such as cryopump, NMR-CT and JJ devices was investigated. Compact heat exchangers, high performance regenerators and reliable compressors are investigated as a critical component technology.

Compact RF ion source for industrial electrostatic ion accelerator

NASA Astrophysics Data System (ADS)

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Compact RF ion source for industrial electrostatic ion accelerator.

PubMed

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Joint U.S. Defense Science Board, UK Defence Scientific Advisory Council Task Force on Defense Critical Technologies

DTIC Science & Technology

2006-03-01

electrons (e.g., betavoltaics ) in a compact package is emerging as a possible new high energy density power source. Proliferation is not an issue...10 13 10 12 10 11 10 10 10 9 10 8 10 7 10 6 10 5 10 2 10 3 10 4 10 5 10 6 10 7 Total Dose [rad) Si )] Strategic Space Strategic Missiles St ra te gi

A Broadband IR Compact High Resolution Spectrometer (BIRCHES) for a Lunar Water Distribution (LWaDi) Cubesat Mission

NASA Astrophysics Data System (ADS)

Clark, Pamela E.; Macdowall, Robert J.; Reuter, Dennis; Mauk, Robin

2014-11-01

We are in the process of developing the BIRCH (Broadband IR for Cubesats with High Resolution) Spectrometer for characterization of a range of deep space targets. BIRCH is the first extremely compact Broadband IR spectrometer with high spectral resolution designed to measure water type and component distribution for a science-driven cubesat mission, such as the lunar orbital mission LWaDi (Lunar Water Distribution) designed to determine the systematics of lunar water and volatiles as a function of time of day, latitude, and terrain. The development of cubesat form factor instruments, such as BIRCH, capable of providing high priority science goals identified in the decadal survey is critical to achieve low cost planetary exploration promised by the cubesat paradigm by exploring volatile systems via orbiting or landed packages. On the Moon, as well as Mercury, Mars, and the asteroids, the source, distribution, and role of volatiles is a question of major importance, and has implications for formation processes, including interior structure, differentiation, and the origin of life in the early solar system. The form and distribution of water has implications for human exploration, resource exploitation, and sample curation. Recent lunar missions gave unanticipated evidence for the water from NIR instruments not optimized for finding it. Our instrument includes a compact broadband HgCdTe detector with a linear variable filter and a compact cryocooler (for operation below 140K) attached to a compact optical system with 2 off-axis parabolic mirrors and variable field stop operating below 240K. Its 10 nm or better resolution and longer wavelength upper range (1.3 to 3.7 microns) are necessary to identify and separate features associated with water type (adsorbed, bound, ice) and components. Its 4-sided adjustable iris at the field stop enables a constant spot size (10 x 10 km) regardless of altitude. BIRCH will be able to provide systematic and extensive enough information to understand water’s life cycle, temporal and spatial distribution and interactions as a function of lunar cycles, characteristic features, and regolith composition.

Status of Fuel Development and Manufacturing for Space Nuclear Reactors at BWX Technologies

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

Carmack, W.J.; Husser, D.L.; Mohr, T.C.

2004-02-04

New advanced nuclear space propulsion systems will soon seek a high temperature, stable fuel form. BWX Technologies Inc (BWXT) has a long history of fuel manufacturing. UO2, UCO, and UCx have been fabricated at BWXT for various US and international programs. Recent efforts at BWXT have focused on establishing the manufacturing techniques and analysis capabilities needed to provide a high quality, high power, compact nuclear reactor for use in space nuclear powered missions. To support the production of a space nuclear reactor, uranium nitride has recently been manufactured by BWXT. In addition, analytical chemistry and analysis techniques have been developedmore » to provide verification and qualification of the uranium nitride production process. The fabrication of a space nuclear reactor will require the ability to place an unclad fuel form into a clad structure for assembly into a reactor core configuration. To this end, BWX Technologies has reestablished its capability for machining, GTA welding, and EB welding of refractory metals. Specifically, BWX Technologies has demonstrated GTA welding of niobium flat plate and EB welding of niobium and Nb-1Zr tubing. In performing these demonstration activities, BWX Technologies has established the necessary infrastructure to manufacture UO2, UCx, or UNx fuel, components, and complete reactor assemblies in support of space nuclear programs.« less

The compact genome of the plant pathogen Plasmodiophora brassicae is adapted to intracellular interactions with host Brassica spp.

PubMed

Rolfe, Stephen A; Strelkov, Stephen E; Links, Matthew G; Clarke, Wayne E; Robinson, Stephen J; Djavaheri, Mohammad; Malinowski, Robert; Haddadi, Parham; Kagale, Sateesh; Parkin, Isobel A P; Taheri, Ali; Borhan, M Hossein

2016-03-31

The protist Plasmodiophora brassicae is a soil-borne pathogen of cruciferous species and the causal agent of clubroot disease of Brassicas including agriculturally important crops such as canola/rapeseed (Brassica napus). P. brassicae has remained an enigmatic plant pathogen and is a rare example of an obligate biotroph that resides entirely inside the host plant cell. The pathogen is the cause of severe yield losses and can render infested fields unsuitable for Brassica crop growth due to the persistence of resting spores in the soil for up to 20 years. To provide insight into the biology of the pathogen and its interaction with its primary host B. napus, we produced a draft genome of P. brassicae pathotypes 3 and 6 (Pb3 and Pb6) that differ in their host range. Pb3 is highly virulent on B. napus (but also infects other Brassica species) while Pb6 infects only vegetable Brassica crops. Both the Pb3 and Pb6 genomes are highly compact, each with a total size of 24.2 Mb, and contain less than 2 % repetitive DNA. Clustering of genome-wide single nucleotide polymorphisms (SNP) of Pb3, Pb6 and three additional re-sequenced pathotypes (Pb2, Pb5 and Pb8) shows a high degree of correlation of cluster grouping with host range. The Pb3 genome features significant reduction of intergenic space with multiple examples of overlapping untranslated regions (UTRs). Dependency on the host for essential nutrients is evident from the loss of genes for the biosynthesis of thiamine and some amino acids and the presence of a wide range of transport proteins, including some unique to P. brassicae. The annotated genes of Pb3 include those with a potential role in the regulation of the plant growth hormones cytokinin and auxin. The expression profile of Pb3 genes, including putative effectors, during infection and their potential role in manipulation of host defence is discussed. The P. brassicae genome sequence reveals a compact genome, a dependency of the pathogen on its host for some essential nutrients and a potential role in the regulation of host plant cytokinin and auxin. Genome annotation supported by RNA sequencing reveals significant reduction in intergenic space which, in addition to low repeat content, has likely contributed to the P. brassicae compact genome.

Dynamically hot galaxies. I - Structural properties

NASA Technical Reports Server (NTRS)

Bender, Ralf; Burstein, David; Faber, S. M.

1992-01-01

Results are reported from an analysis of the structural properties of dynamically hot galaxies which combines central velocity dispersion, effective surface brightness, and effective radius into a new 3-space (k), in which the axes are parameters that are physically meaningful. Hot galaxies are found to divide into groups in k-space that closely parallel conventional morphological classifications, namely, luminous ellipticals, compacts, bulges, bright dwarfs, and dwarf spheroidals. A major sequence is defined by luminous ellipticals, bulges, and most compacts, which together constitute a smooth continuum in k-space. Several properties vary smoothly with mass along this continuum, including bulge-to-disk ratio, radio properties, rotation, degree of velocity anisotropy, and 'unrelaxed'. A second major sequence is comprised of dwarf ellipticals and dwarf spheroidals. It is suggested that mass loss is a major factor in hot dwarf galaxies, but the dwarf sequence cannot be simply a mass-loss sequence, as it has the wrong direction in k-space.

An ultra-stable iodine-based frequency reference for space applications

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Braxmaier, Claus; Doeringshoff, Klaus; Keetman, Anja; Reggentin, Matthias; Kovalchuk, Evgeny; Peters, Achim

2012-07-01

Future space missions require for ultra-stable optical frequency references. Examples are the gravitational wave detector LISA/eLISA (Laser Interferometer Space Antenna), the SpaceTime Asymmetry Research (STAR) program, the aperture-synthesis telescope Darwin and the GRACE (Gravity Recovery and Climate Experiment) follow on mission exploring Earth's gravity. As high long-term frequency stability is required, lasers stabilized to atomic or molecular transitions are preferred, also offering an absolute frequency reference. Frequency stabilities in the 10 ^{-15} domains at longer integration times (up to several hours) are demonstrated in laboratory experiments using setups based on Doppler-free spectroscopy. Such setups with a frequency stability comparable to the hydrogen maser in the microwave domain, have the potential to be developed space compatible on a relatively short time scale. Here, we present the development of ultra-stable optical frequency references based on modulation-transfer spectroscopy of molecular iodine. Noise levels of 2\\cdot10 ^{-14} at an integration time of 1 s and below 3\\cdot10 ^{-15} at integration times between 100 s and 1000 s are demonstrated with a laboratory setup using an 80 cm long iodine cell in single-pass configuration in combination with a frequency-doubled Nd:YAG laser and standard optical components and optomechanic mounts. The frequency stability at longer integration times is (amongst other things) limited by the dimensional stability of the optical setup, i.e. by th pointing stability of the two counter-propagating beams overlapped in the iodine cell. With the goal of a future space compatible setup, a compact frequency standard on EBB (elegant breadboard) level was realized. The spectroscopy unit utilizes a baseplate made of Clearceram-HS, a glass ceramics with an ultra-low coefficient of thermal expansion of 2\\cdot10 ^{-8} K ^{-1}. The optical components are joint to the baseplate using adhesive bonding technology, which was developed in a cooperation of HTWG Konstanz and Astrium Friedrichshafen. This setup ensures a higher long-term frequency stability due to enhanced pointing stability. Also, it takes into account space mission related criteria such as compactness, robustness, MAIVT and environmental influences (shock, vibration and thermal tests). The assembly-integration technology was already successfully environmentally tested and demonstrated in a previous setup of a compact fiber-coupled heterodyne interferometer, which serves as a demonstrator for the optical readout of the LISA gravitational reference sensor. We present first measurements of the EBB setup and a first design of an iodine frequency standard on engineering model (EM) level. The EM-setup is based on the EBB experience, but features smaller dimensions by using a multipass iodine cell and less optical components. Financial support by the German Space Agency DLR with funds provided by the Federal Ministry of Economics and Technology (BMWi) under grant number 50 QT 1102 is highly appreciated.

High-power VCSEL systems and applications

NASA Astrophysics Data System (ADS)

Moench, Holger; Conrads, Ralf; Deppe, Carsten; Derra, Guenther; Gronenborn, Stephan; Gu, Xi; Heusler, Gero; Kolb, Johanna; Miller, Michael; Pekarski, Pavel; Pollmann-Retsch, Jens; Pruijmboom, Armand; Weichmann, Ulrich

2015-03-01

Easy system design, compactness and a uniform power distribution define the basic advantages of high power VCSEL systems. Full addressability in space and time add new dimensions for optimization and enable "digital photonic production". Many thermal processes benefit from the improved control i.e. heat is applied exactly where and when it is needed. The compact VCSEL systems can be integrated into most manufacturing equipment, replacing batch processes using large furnaces and reducing energy consumption. This paper will present how recent technological development of high power VCSEL systems will extend efficiency and flexibility of thermal processes and replace not only laser systems, lamps and furnaces but enable new ways of production. High power VCSEL systems are made from many VCSEL chips, each comprising thousands of low power VCSELs. Systems scalable in power from watts to multiple ten kilowatts and with various form factors utilize a common modular building block concept. Designs for reliable high power VCSEL arrays and systems can be developed and tested on each building block level and benefit from the low power density and excellent reliability of the VCSELs. Furthermore advanced assembly concepts aim to reduce the number of individual processes and components and make the whole system even more simple and reliable.

Bright compact bulges at intermediate redshifts

NASA Astrophysics Data System (ADS)

Sachdeva, Sonali; Saha, Kanak

2018-07-01

Studying bright (MB < -20), intermediate-redshift (0.4 < z< 1.0), disc-dominated (nB < 2.5) galaxies from Hubble Space Telescope/Advanced Camera for Surveys and Wide Field Camera 3 in Chandra Deep Field-South, in rest-frame B and I band, we found a new class of bulges that is brighter and more compact than ellipticals. We refer to them as `bright, compact bulges' (BCBs) - they resemble neither classical nor pseudo-bulges and constitute ˜12 per cent of the total bulge population at these redshifts. Examining free-bulge + disc decomposition sample and elliptical galaxy sample from Simard et al., we find that only ˜0.2 per cent of the bulges can be classified as BCBs in the local Universe. Bulge to total light ratio of disc galaxies with BCBs is (at ˜0.4) a factor of ˜2 and ˜4 larger than for those with classical and pseudo-bulges. BCBs are ˜2.5 and ˜6 times more massive than classical and pseudo-bulges. Although disc galaxies with BCBs host the most massive and dominant bulge type, their specific star formation rate is 1.5-2 times higher than other disc galaxies. This is contrary to the expectations that a massive compact bulge would lead to lower star formation rates. We speculate that our BCB host disc galaxies are descendant of massive, compact, and passive elliptical galaxies observed at higher redshifts. Those high-redshift ellipticals lack local counterparts and possibly evolved by acquiring a compact disc around them. The overall properties of BCBs support a picture of galaxy assembly in which younger discs are being accreted around massive pre-existing spheroids.

Acousto-optic time- and space-integrating spotlight-mode SAR processor

NASA Astrophysics Data System (ADS)

Haney, Michael W.; Levy, James J.; Michael, Robert R., Jr.

1993-09-01

The technical approach and recent experimental results for the acousto-optic time- and space- integrating real-time SAR image formation processor program are reported. The concept overcomes the size and power consumption limitations of electronic approaches by using compact, rugged, and low-power analog optical signal processing techniques for the most computationally taxing portions of the SAR imaging problem. Flexibility and performance are maintained by the use of digital electronics for the critical low-complexity filter generation and output image processing functions. The results include a demonstration of the processor's ability to perform high-resolution spotlight-mode SAR imaging by simultaneously compensating for range migration and range/azimuth coupling in the analog optical domain, thereby avoiding a highly power-consuming digital interpolation or reformatting operation usually required in all-electronic approaches.

Advanced Compact Holographic Data Storage System

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Zhou, Hanying; Reyes, George

2000-01-01

JPL, under current sponsorship from NASA Space Science and Earth Science Programs, is developing a high-density, nonvolatile and rad-hard Advanced Holographic Memory (AHM) system to enable large-capacity, high-speed, low power consumption, and read/write of data in a space environment. The entire read/write operation will be controlled with electro-optic mechanism without any moving parts. This CHDS will consist of laser diodes, photorefractive crystal, spatial light modulator, photodetector array, and I/O electronic interface. In operation, pages of information would be recorded and retrieved with random access and highspeed. The nonvolatile, rad-hard characteristics of the holographic memory will provide a revolutionary memory technology to enhance mission capabilities for all NASA's Earth Science Mission. In this paper, recent technology progress in developing this CHDS at JPL will be presented.

Hybrid propulsion technology program: Phase 1, volume 2

NASA Technical Reports Server (NTRS)

Schuler, A. L.; Wiley, D. R.

1989-01-01

The program objectives of developing hybrid propulsion technology (HPT) to enable its application for manned and unmanned high thrust, high performance space launch vehicles are examined. The studies indicate that the hybrid propulsion (HP) is very attractive, especially when applied to large boosters for programs such as the Advanced Launch System (ALS) and the second generation Space Shuttle. Some of the advantages of HP are identified. Space launch vehicles using HP are less costly than those flying today because their propellant and insulation costs are much less and there are fewer operational restraints due to reduced safety requirements. Boosters using HP have safety features that are highly desirable, particularly for manned flights. HP systems will have a clean exhaust and high performance. Boosters using HP readily integrate with launch vehicles and their launch operations, because they are very compact for the amount of energy contained. Hybrid propulsion will increase the probability of mission success. In order to properly develop the technologies of HP, preliminary HP concepts are evaluated. System analyses and trade studies were performed to identify technologies applicable to HP.

Heat Melt Compaction as an Effective Treatment for Eliminating Microorganisms from Solid Waste

NASA Technical Reports Server (NTRS)

Hummerick, Mary P.; Strayer, Richard; McCoy, LaShelle; Richard, Jeffrey; Ruby, Anna; Wheeler, Raymond

2012-01-01

One of the technologies being tested at Ames Research Center as part of the logistics and repurposing project is heat melt compaction (HMC) of solid waste to reduce volume, remove water and render a biologically stable and safe product. Studies at Kennedy Space Center have focused on the efficacy of the heat melt compaction process for killing microorganisms in waste and specific compacter operation protocols, i.e., time and temperature, required to achieve a sterile, stable product. The work reported here includes a controlled study to examine the survival and potential re-growth of specific microorganisms over a 6-month period of storage after heating and compaction. Before heating and compaction, ersatz solid wastes were inoculated with Bacillus amyloliquefaciens and Rhodotorula mucilaginosa, previously isolated from recovered space shuttle mission food and packaging waste. Compacted HMC tiles were sampled for microbiological analysis at time points between 0 and 180 days of storage in a controlled environment chamber. In addition, biological indicator strips containing spores of Bacillus atrophaeus and Ceo bacillus stearothermophilus were imbedded in trash to assess the efficacy of the HMC process to achieve sterilization. Analysis of several tiles compacted at 180 C for times of 40 minutes to over 2 hours detected organisms in all tile samples with the exception of one exposed to 180 C for approximately 2 hours. Neither of the inoculated organisms was recovered, and the biological indicator strips were negative for growth in all tiles indicating at least local sterilization of tile areas. The findings suggest that minimum time/temperature combination is required for complete sterilization. Microbial analysis of tiles processed at lower temperatures from 130 C-150 C at varying times will be discussed, as well as analysis of the bacteria and fungi present on the compactor hardware as a result of exposure to the waste and the surrounding environment. The two organisms inoculated into the waste were among those isolated and identified from the HMC surfaces indicating the possibility of cross contamination.

High-Resolution Mapping of Yield Curve Shape and Evolution for Porous Rock: The Effect of Inelastic Compaction on Porous Bassanite

NASA Astrophysics Data System (ADS)

Bedford, John D.; Faulkner, Daniel R.; Leclère, Henri; Wheeler, John

2018-02-01

Porous rock deformation has important implications for fluid flow in a range of crustal settings as compaction can increase fluid pressure and alter permeability. The onset of inelastic strain for porous materials is typically defined by a yield curve plotted in differential stress (Q) versus effective mean stress (P) space. Empirical studies have shown that these curves are broadly elliptical in shape. Here conventional triaxial experiments are first performed to document (a) the yield curve of porous bassanite (porosity ≈ 27-28%), a material formed from the dehydration of gypsum, and (b) the postyield behavior, assuming that P and Q track along the yield surface as inelastic deformation accumulates. The data reveal that after initial yield, the yield surface cannot be perfectly elliptical and must evolve significantly as inelastic strain is accumulated. To investigate this further, a novel stress-probing methodology is developed to map precisely the yield curve shape and subsequent evolution for a single sample. These measurements confirm that the high-pressure side of the curve is partly composed of a near-vertical limb. Yield curve evolution is shown to be dependent on the nature of the loading path. Bassanite compacted under differential stress develops a heterogeneous microstructure and has a yield curve with a peak that is almost double that of an equal porosity sample that has been compacted hydrostatically. The dramatic effect of different loading histories on the strength of porous bassanite highlights the importance of understanding the associated microstructural controls on the nature of inelastic deformation in porous rock.

A Large-Particle Monte Carlo Code for Simulating Non-Linear High-Energy Processes Near Compact Objects

NASA Technical Reports Server (NTRS)

Stern, Boris E.; Svensson, Roland; Begelman, Mitchell C.; Sikora, Marek

1995-01-01

High-energy radiation processes in compact cosmic objects are often expected to have a strongly non-linear behavior. Such behavior is shown, for example, by electron-positron pair cascades and the time evolution of relativistic proton distributions in dense radiation fields. Three independent techniques have been developed to simulate these non-linear problems: the kinetic equation approach; the phase-space density (PSD) Monte Carlo method; and the large-particle (LP) Monte Carlo method. In this paper, we present the latest version of the LP method and compare it with the other methods. The efficiency of the method in treating geometrically complex problems is illustrated by showing results of simulations of 1D, 2D and 3D systems. The method is shown to be powerful enough to treat non-spherical geometries, including such effects as bulk motion of the background plasma, reflection of radiation from cold matter, and anisotropic distributions of radiating particles. It can therefore be applied to simulate high-energy processes in such astrophysical systems as accretion discs with coronae, relativistic jets, pulsar magnetospheres and gamma-ray bursts.

Upgrade of the compact neutron spectrometer for high flux environments

NASA Astrophysics Data System (ADS)

Osipenko, M.; Bellucci, A.; Ceriale, V.; Corsini, D.; Gariano, G.; Gatti, F.; Girolami, M.; Minutoli, S.; Panza, F.; Pillon, M.; Ripani, M.; Trucchi, D. M.

2018-03-01

In this paper new version of the 6Li-based neutron spectrometer for high flux environments is described. The new spectrometer was built with commercial single crystal Chemical Vapour Deposition diamonds of electronic grade. These crystals feature better charge collection as well as higher radiation hardness. New metal contacts approaching ohmic conditions were deposited on the diamonds suppressing build-up of space charge observed in the previous prototypes. New passive preamplification of the signal at detector side was implemented to improve its resolution. This preamplification is based on the RF transformer not sensitive to high neutron flux. The compact mechanical design allowed to reduce detector size to a tube of 1 cm diameter and 13 cm long. The spectrometer was tested in the thermal column of TRIGA reactor and at the DD neutron generator. The test results indicate an energy resolution of 300 keV (FWHM), reduced to 72 keV (RMS) excluding energy loss, and coincidence timing resolution of 160 ps (FWHM). The measured data are in agreement with Geant4 simulations except for larger energy loss tail presumably related to imperfections of metal contacts and glue expansion.

Progress in Laser Risk Reduction for 1 micron lasers at GSFC

NASA Technical Reports Server (NTRS)

Heaps, William S.

2007-01-01

In recent years, lasers have proven themselves to be invaluable to a variety of remote sensing applications. LIDAR techniques have been used to measure atmospheric aerosols and a variety of trace species, profile winds, and develop high resolution topographical maps. Often it would be of great advantage to make these measurements from an orbiting satellite. Unfortunately, the space environment is a challenging one for the high power lasers that would enable many LIDAR missions. Optical mounts must maintain precision alignment during and after launch. Outgassing materials in the vacuum of space lead to contamination of laser optics. Electronic components and optical materials must survive the space environment, including a vacuum atmosphere, thermal cycling, and radiation exposure. Laser designs must be lightweight, compact, and energy efficient. Many LIDAR applications require frequency conversion systems that have never been designed or tested for use in space. For the last six years the National Aeronautical and Space Administration (NASA) has undertaken a program specifically directed at addressing the durability and long term reliability issues that face space-borne lasers. The effort is shared between NASA Goddard Space Flight Center in Greenbelt, Maryland, and NASA Langley Research Center in Hampton, Virginia. This paper is an overview of the issues facing space-borne lasers and the efforts that Goddard has been pursuing to address them.

Fiber-Based Lasers as an Option for GRACE Follow-On Light Source

NASA Technical Reports Server (NTRS)

Camp, Jordan

2010-01-01

Fiber based lasers offer a number of attractive characteristics for space application: state of the art laser technology, leverage of design and reliability from the substantial investments of the telecon industry, and convenient redundancy of higher risk components through fiber splicing. At NASA/Goddard we are currently investigating three GFO fiber-based laser options: a fiber oscillator built in our laboratory; an effort to space qualify a commercial design that uses a proprietary high-gain fiber cavity; and the space qualification of a promising new commercial external cavity laser, notable for its low-mass, compact design. In my talk I will outline these efforts, and suggest that the GFO Project may soon have the option of a US laser vendor for its light source.

Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

Combining Sense and Intelligence for Smart Structures

NASA Technical Reports Server (NTRS)

2002-01-01

IFOS developed the I*Sense technology with assistance from a NASA Langley Research Center SBIR contract. NASA and IFOS collaborated to create sensing network designs that have high sensitivity, low power consumption, and significant potential for mass production. The joint- research effort led to the development of a module that is rugged, compact and light-weight, and immune to electromagnetic interference. These features make the I*Sense multisensor arrays favorable for smart structure applications, including smart buildings, bridges, highways, dams, power plants, ships, and oil tankers, as well as space vehicles, space stations, and other space structures. For instance, the system can be used as an early warning and detection device, with alarms being set to monitor the maximum allowable strain and stress values at various points of a given structure.

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

Stottmeister, Alexander, E-mail: alexander.stottmeister@gravity.fau.de; Thiemann, Thomas, E-mail: thomas.thiemann@gravity.fau.de

In this article, the second of three, we discuss and develop the basis of a Weyl quantisation for compact Lie groups aiming at loop quantum gravity-type models. This Weyl quantisation may serve as the main mathematical tool to implement the program of space adiabatic perturbation theory in such models. As we already argued in our first article, space adiabatic perturbation theory offers an ideal framework to overcome the obstacles that hinder the direct implementation of the conventional Born-Oppenheimer approach in the canonical formulation of loop quantum gravity. Additionally, we conjecture the existence of a new form of the Segal-Bargmann-Hall “coherentmore » state” transform for compact Lie groups G, which we prove for G = U(1){sup n} and support by numerical evidence for G = SU(2). The reason for conjoining this conjecture with the main topic of this article originates in the observation that the coherent state transform can be used as a basic building block of a coherent state quantisation (Berezin quantisation) for compact Lie groups G. But, as Weyl and Berezin quantisation for ℝ{sup 2d} are intimately related by heat kernel evolution, it is natural to ask whether a similar connection exists for compact Lie groups as well. Moreover, since the formulation of space adiabatic perturbation theory requires a (deformation) quantisation as minimal input, we analyse the question to what extent the coherent state quantisation, defined by the Segal-Bargmann-Hall transform, can serve as basis of the former.« less

Weak Compactness and Control Measures in the Space of Unbounded Measures

PubMed Central

Brooks, James K.; Dinculeanu, Nicolae

1972-01-01

We present a synthesis theorem for a family of locally equivalent measures defined on a ring of sets. This theorem is then used to exhibit a control measure for weakly compact sets of unbounded measures. In addition, the existence of a local control measure for locally strongly bounded vector measures is proved by means of the synthesis theorem. PMID:16591980

Cohomologie des Groupes Localement Compacts et Produits Tensoriels Continus de Representations

ERIC Educational Resources Information Center

Guichardet, A.

1976-01-01

Contains few and sometimes incomplete proofs on continuous tensor products of Hilbert spaces and of group representations, and on the irreducibility of the latter. Theory of continuous tensor products of Hilbert Spaces is closely related to that of conditionally positive definite functions; it relies on the technique of symmetric Hilbert spaces,…

Novel Low-Cost, Low-Power Miniature Thermionic Cathode Developed for Microwave/Millimeter Wave Tube and Cathode Ray Tube Applications

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.

1999-01-01

A low cost, small size and mass, low heater power, durable high-performance barium dispenser thermionic cathode has been developed that offers significant advancements in the design, manufacture, and performance of the electron sources used in vacuum electronic devices--such as microwave (and millimeter wave) traveling-wave tubes (TWT's)--and in display devices such as high-brightness, high-resolution cathode ray tubes (CRT's). The lower cathode heater power and the reduced size and mass of the new cathode are expected to be especially beneficial in TWT's for deep space communications, where future missions are requiring smaller spacecraft, higher data transfer rates (higher frequencies and radiofrequency output power), and greater electrical efficiency. Also expected to benefit are TWT's for commercial and government communication satellites, for both low and geosynchronous Earth orbit, with additional benefits offered by lower cost and potentially higher cathode current loading. A particularly important TWT application is in the microwave power module (MPM), which is a hybrid microwave (or millimeter wave) amplifier consisting of a low-noise solid state driver, a vacuum power booster (small TWT), and an electronic power conditioner integrated into a single compact package. The attributes of compactness and potentially high electrical efficiency make the MPM very attractive for many commercial and government (civilian and defense) applications in communication and radar systems. The MPM is already finding application in defense electronic systems and is under development by NASA for deep space communications. However, for the MPM to become competitive and commercially successful, a major reduction in cost must be achieved.

Compact orthogonal NMR field sensor

DOEpatents

Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL

2009-02-03

A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

Non-compact nonlinear sigma models

NASA Astrophysics Data System (ADS)

de Rham, Claudia; Tolley, Andrew J.; Zhou, Shuang-Yong

2016-09-01

The target space of a nonlinear sigma model is usually required to be positive definite to avoid ghosts. We introduce a unique class of nonlinear sigma models where the target space metric has a Lorentzian signature, thus the associated group being non-compact. We show that the would-be ghost associated with the negative direction is fully projected out by 2 second-class constraints, and there exist stable solutions in this class of models. This result also has important implications for Lorentz-invariant massive gravity: There exist stable nontrivial vacua in massive gravity that are free from any linear vDVZ-discontinuity and a Λ2 decoupling limit can be defined on these vacua.

Compact electrostatic comb actuator

DOEpatents

Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

2000-01-01

A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

Signatures of extra dimensions in gravitational waves

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

Andriot, David; Gómez, Gustavo Lucena, E-mail: andriotphysics@gmail.com, E-mail: glucenag@aei.mpg.de

2017-06-01

Considering gravitational waves propagating on the most general 4+ N -dimensional space-time, we investigate the effects due to the N extra dimensions on the four-dimensional waves. All wave equations are derived in general and discussed. On Minkowski{sub 4} times an arbitrary Ricci-flat compact manifold, we find: a massless wave with an additional polarization, the breathing mode, and extra waves with high frequencies fixed by Kaluza-Klein masses. We discuss whether these two effects could be observed.

A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope (HST) Grism Spectroscopy

NASA Technical Reports Server (NTRS)

Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel K.; Gardner, Jonathan P.; Dickinson, Mark; Pirzkal, Norbert; Spinrad, Hyron; Reddy, Naveen; Dey, Arjun; Hathi, Nimish;

Plasma simulation in a hybrid ion electric propulsion system

NASA Astrophysics Data System (ADS)

Jugroot, Manish; Christou, Alex

2015-04-01

An exciting possibility for the next generation of satellite technology is the microsatellite. These satellites, ranging from 10-500 kg, can offer advantages in cost, reduced risk, and increased functionality for a variety of missions. For station keeping and control of these satellites, a suitable compact and high efficiency thruster is required. Electrostatic propulsion provides a promising solution for microsatellite thrust due to their high specific impulse. The rare gas propellant is ionized into plasma and generates a beam of high speed ions by electrostatic processes. A concept explored in this work is a hybrid combination of dc ion engines and hall thrusters to overcome space-charge and lifetime limitations of current ion thruster technologies. A multiphysics space and time-dependent formulation was used to investigate and understand the underlying physical phenomena. Several regions and time scales of the plasma have been observed and will be discussed.

Prospect of space-based interferometry at EUV and soft X-ray wavelengths

NASA Technical Reports Server (NTRS)

Welsh, Barry Y.; Chakrabarti, Supriya

1992-01-01

We review the current capabilities of high-resolution, spectroscopic, space-borne instrumentation available for both solar and stellar observations in the EUV and soft X-ray wavelength regimes, and describe the basic design of a compact, all-reflection interferometer based on the spatial heterodyne technique; this is capable of producing a resolving power (lambda/Delta-lambda) of about 20,000 in the 100-200 A region using presently available multilayer optical components. Such an instrument can be readily constructed with existing technology. Due to its small size and lack of moving parts, it is ideally suited to spaceborne applications. Based on best estimates of the efficiency of this instrument at soft X-ray wavelengths, we review the possible use of this high-resolution interferometer in obtaining high-resolution full-disk spectroscopy of the sun. We also discuss its possible use for observations of diffuse sources such as the EUV interstellar background radiation.

A comparison of DNA compaction by arginine and lysine peptides: A physical basis for arginine rich protamines

PubMed Central

DeRouchey, Jason; Hoover, Brandon

2013-01-01

Protamines are small, highly positively charged peptides used to package DNA to very high densities in sperm nuclei. Tight DNA packing is considered essential to minimize DNA damage by mutagens and reactive oxidizing species. A striking and general feature of protamines is the almost exclusive use of arginine over lysine for the positive charge to neutralize DNA. We have investigated whether this preference for arginine might arise from a difference in DNA condensation by arginine and lysine peptides. The forces underlying DNA compaction by arginine, lysine, and ornithine peptides are measured using the osmotic stress technique coupled with x-ray scattering. The equilibrium spacings between DNA helices condensed by lysine and ornithine peptides are significantly larger than the interhelical distances with comparable arginine peptides. The DNA surface-to-surface separation, for example, is some 50% larger with poly-lysine compared to poly-arginine. DNA packing by lysine rich peptides in sperm nuclei would allow much greater accessibility to small molecules that could damage DNA. The larger spacing with lysine peptides is due to both a weaker attraction and a stronger short ranged repulsion relative to the arginine peptides. A previously proposed model for poly-arginine and protamine binding to DNA provides a convenient framework for understanding the differences between the ability of lysine and arginine peptides to assemble DNA. PMID:23540557

POX 186: A Dwarf Galaxy Under Construction?

NASA Astrophysics Data System (ADS)

Corbin, M. R.; Vacca, W. D.

2000-12-01

We have obtained deep images of the ultracompact ( ~ 3'') blue compact dwarf galaxy POX 186 in the F336W, F555W, and F814W filters of the Planetary Camera of the Hubble Space Telescope. We have additionally obtained a low-resolution near ultraviolet spectrum of the object with STIS and combine this with a ground-based spectrum covering the visible continuum and emission lines. Our images confirm this object to be highly compact, with a maximum projected size of only ~ 240 pc, making it one of the smallest galaxies known. We also confirm that the outer regions of the galaxy consist of an evolved stellar population, ruling out earlier speculations that POX 186 is a protogalaxy. However, the PC images reveal the galaxy to have a highly irregular morphology, with a pronounced tidal arm on its western side. This morphology is strongly suggestive of a recent collision between two smaller components which has in turn triggered the central starburst. The F336W image also shows that the material in this tidal stream is actively star forming. Given the very small ( ~ 100 pc) sizes of the colliding components, POX 186 may be a dwarf galaxy in the early stages of formation, which would be consistent with current ``downsizing'' models of galaxy formation in which the least massive objects are the last to form. This work is supported by NASA and the Space Telescope Science Institute.

Fatigue behavior of highly porous titanium produced by powder metallurgy with temporary space holders.

PubMed

Özbilen, Sedat; Liebert, Daniela; Beck, Tilmann; Bram, Martin

2016-03-01

Porous titanium cylinders were produced with a constant amount of temporary space holder (70 vol.%). Different interstitial contents were achieved by varying the starting powders (HDH vs. gas atomized) and manufacturing method (cold compaction without organic binders vs. warm compaction of MIM feedstocks). Interstitial contents (O, C, and N) as a function of manufacturing were measured by chemical analysis. Samples contained 0.34-0.58 wt.% oxygen, which was found to have the greatest effect on mechanical properties. Quasi-static mechanical tests under compression at low strain rate were used for reference and to define parameters for cyclic compression tests. Not unexpectedly, increased oxygen content increased the yield strength of the porous titanium. Cyclic compression fatigue tests were conducted using sinusoidal loading in a servo-hydraulic testing machine. Increased oxygen content was concomitant with embrittlement of the titanium matrix, resulting in significant reduction of compression cycles before failure. For samples with 0.34 wt.% oxygen, R, σ(min) and σ(max) were varied systematically to estimate the fatigue limit (~4 million cycles). Microstructural changes induced by cyclic loading were then characterized by optical microscopy, SEM and EBSD. Copyright © 2015 Elsevier B.V. All rights reserved.

Compact spectrometer for precision studies of multimode behavior in an extended-cavity diode laser

NASA Astrophysics Data System (ADS)

Roach, Timothy; Golemi, Josian; Krueger, Thomas

2016-05-01

We have built a compact, inexpensive, high-precision spectrometer and used it to investigate the tuning behavior of a grating stabilized extended-cavity diode laser (ECDL). A common ECDL design uses a laser chip with an uncoated (partially reflecting) front facet, and the laser output exhibits a complicated pattern of mode hops as the frequency is tuned, in some cases even showing chaotic dynamics. Our grating spectrometer (based on a design by White & Scholten) monitors a span of 4000 GHz (8 nm at 780 nm) with a linewidth of 3 GHz, which with line-splitting gives a precision of 0.02 GHz in determining the frequency of a laser mode. We have studied multimode operation of the ECDL, tracking two or three simultaneous chip cavity modes (spacing ~ 30 GHz) during tuning via current or piezo control of the external cavity. Simultaneous output on adjacent external cavity modes (spacing ~ 5 GHz) is monitored by measuring an increase in the spectral linewidth. Computer-control of the spectrometer (for line-fitting and averaging) and of the ECDL (electronic tuning) allows rapid collection of spectral data sets, which we will use to test mathematical simulation models of the non-linear laser cavity interactions.

Compact and Light-Weight Solar Spaceflight Instrument Designs Utilizing Newly Developed Miniature Free-Standing Zone Plates: EUV Radiometer and Limb-Scanning Monochromator

NASA Astrophysics Data System (ADS)

Seely, J. F.; McMullin, D. R.; Bremer, J.; Chang, C.; Sakdinawat, A.; Jones, A. R.; Vest, R.

2014-12-01

Two solar instrument designs are presented that utilize newly developed miniature free-standing zone plates having interconnected Au opaque bars and no support membrane resulting in excellent long-term stability in space. Both instruments are based on a zone plate having 4 mm outer diameter and 1 to 2 degree field of view. The zone plate collects EUV radiation and focuses a narrow bandpass through a pinhole aperture and onto a silicon photodiode detector. As a miniature radiometer, EUV irradiance is accurately determined from the zone plate efficiency and the photodiode responsivity that are calibrated at the NIST SURF synchrotron facility. The EUV radiometer is pointed to the Sun and measures the absolute solar EUV irradiance in high time cadence suitable for solar physics and space weather applications. As a limb-scanning instrument in low earth orbit, a miniature zone-plate monochromator measures the extinction of solar EUV radiation by scattering through the upper atmosphere which is a measure of the variability of the ionosphere. Both instruments are compact and light-weight and are attractive for CubeSats and other missions where resources are extremely limited.

COMPACT: The role of soil management in mitigating catchment flood risk

NASA Astrophysics Data System (ADS)

Pattison, Ian; Coates, Victoria; Frost, Matthew; Demirci, Emrah

2017-04-01

This paper reports a new NERC funded research project which addresses the impact of agricultural soil compaction on surface runoff and catchment scale flood risk. The intensification of agriculture, through increasing the number of animals in pasture, and the use of larger, heavier machinery for arable farming, over the past 50 years or so is hypothesised to have had an impact on the severity and frequency of flooding. These land management practices cause soil compaction, which reduces the rate of rainfall infiltration and the volume of water that can be stored within the sub-surface. This results in more rainfall being partitioned into the faster surface runoff pathway into rivers and potentially causing flooding downstream. However, the level of soil compaction is highly heterogeneous over space and time. This is because different animals i.e. cattle, sheep and horses, exert different loads on the soil and are kept at different densities. Furthermore, farm animals are known to exhibit behaviour whereby certain parts of the field are moved over more frequently than others. The same is the case in arable farming practices, whereby ploughing forms tramlines or wheelings, which are more compacted. Different forms of management practice ranging from zero-tillage to conventional cultivation exert different pressures on the soil at different times of year. However, very little is known about this variability of soil compaction levels at the sub-field level and land under different management practices. This research aims to quantify this sub-field variation in compaction severity and depths through using novel Ground Penetrating Radar (GPR) and Animal tracking GPS technology. Combining these with more conventional soil property tests, including bulk density, saturated hydraulic conductivity and using a penetrometer will allow relationships with frequency of load to be developed over different spatial and temporal scales. Furthermore, X-Ray CT scanning will reveal the fine scale impacts of compaction on soil structure. This data will form the input to a physically based, reduced complexity, spatially distributed hydrological model to test feasible "what if?" scenarios. This will upscale local changes in land management and soil characteristics to catchment scale flooding. Results from research focussing on a priori compacted areas, such as feeding areas, field gates, shelter zones and tractor wheelings show that these are statistically different to areas assumed to be less compacted in the open field.

Design and Performance Tests of Ultra-Compact Calorimeters for High Energy Astrophysics

NASA Technical Reports Server (NTRS)

Salgado, Carlos W.

2003-01-01

This R&D project had two goals: a) the study of general-application ultra-compact calorimetry technologies for use in High Energy Astrophysics and, b) contribute to the design of an efficient calorimeter for the ACCESS mission. The direct measurement of galactic cosmic ray fluxes is performed from space or from balloon-borne detectors. Detectors used in those studies are limited in size and, specially, in weight. Since galactic cosmic ray fluxes are very small, detectors with high geometrical acceptances and long exposures are usually required for collecting enough statistics. We have studied calorimeter techniques that could produce large geometrical acceptance per unit of mass (G/w) and that may be used to study galactic cosmic rays at intermediate energies (knee energies).-The most important asset for detection of primary cosmic rays at and about the knee is large acceptance. To construct a large acceptance calorimeter (this term is used here in its most general accepted meaning of calorimeter as a device to measure particle energies ) the detector needs to be verv liaht or verv shallow . We studied two possible technologies to built compact calorimeters: the use of lead-tungstate crystals (PWO) and the use of sampling calorimetry using scintillating fibers embedded in a matrix of powder tungsten. For a very light detector, we considered the possibility of using Optical Transition Radiation (OTR) to measure the energy (and perhaps also direction and identity) of VHE cosmic rays.

Renorming c0 and closed, bounded, convex sets with fixed point property for affine nonexpansive mappings

NASA Astrophysics Data System (ADS)

Nezir, Veysel; Mustafa, Nizami

2017-04-01

In 2008, P.K. Lin provided the first example of a nonreflexive space that can be renormed to have fixed point property for nonexpansive mappings. This space was the Banach space of absolutely summable sequences l1 and researchers aim to generalize this to c0, Banach space of null sequences. Before P.K. Lin's intriguing result, in 1979, Goebel and Kuczumow showed that there is a large class of non-weak* compact closed, bounded, convex subsets of l1 with fixed point property for nonexpansive mappings. Then, P.K. Lin inspired by Goebel and Kuczumow's ideas to give his result. Similarly to P.K. Lin's study, Hernández-Linares worked on L1 and in his Ph.D. thesis, supervisored under Maria Japón, showed that L1 can be renormed to have fixed point property for affine nonexpansive mappings. Then, related questions for c0 have been considered by researchers. Recently, Nezir constructed several equivalent norms on c0 and showed that there are non-weakly compact closed, bounded, convex subsets of c0 with fixed point property for affine nonexpansive mappings. In this study, we construct a family of equivalent norms containing those developed by Nezir as well and show that there exists a large class of non-weakly compact closed, bounded, convex subsets of c0 with fixed point property for affine nonexpansive mappings.

Development of mechanical structure for the compact space IR camera MIRIS

NASA Astrophysics Data System (ADS)

Moon, Bongkon; Jeong, Woong-Seob; Cha, Sang-Mok; Park, Youngsik; Ree, Chang-Hee; Lee, Dae-Hee; Park, Sung-Joon; Nam, Uk-Won; Park, Jang-Hyun; Ka, Nung Hyun; Lee, Mi Hyun; Lee, Duk-Hang; Pyo, Jeonghyun; Rhee, Seung-Woo; Park, Jong-Oh; Lee, Hyung-Mok; Matsumoto, Toshio; Yang, Sun Choel; Han, Wonyong

2010-07-01

MIRIS is a compact near-infrared camera with a wide field of view of 3.67°×3.67° in the Korea Science and Technology Satellite 3 (STSAT-3). MIRIS will be launched warm and cool the telescope optics below 200K by pointing to the deep space on Sun-synchronous orbit. In order to realize the passive cooling, the mechanical structure was designed to consider thermal analysis results on orbit. Structural analysis was also conducted to ensure safety and stability in launching environments. To achieve structural and thermal requirements, we fabricated the thermal shielding parts such as Glass Fiber Reinforced Plastic (GFRP) pipe supports, a Winston cone baffle, aluminum-shield plates, a sunshade, a radiator and 30 layers of Multi Layer Insulation (MLI). These structures prevent the heat load from the spacecraft and the earth effectively, and maintain the temperature of the telescope optics within operating range. A micro cooler was installed in a cold box including a PICNIC detector and a filter-wheel, and cooled the detector down to a operating temperature range. We tested the passive cooling in the simulated space environment and confirmed that the required temperature of telescope can be achieved. Driving mechanism of the filter-wheel and the cold box structure were also developed for the compact space IR camera. Finally, we present the assembly procedures and the test result for the mechanical parts of MIRIS.

Latest developments for low-power infrared laser-based trace gas sensors for sensor networks

NASA Astrophysics Data System (ADS)

So, Stephen; Thomazy, David; Wang, Wen; Marchat, Oscar; Wysocki, Gerard

2011-09-01

Academic and industrial researchers require ultra-low power, compact laser based trace-gas sensor systems for the most demanding environmental and space-borne applications. Here the latest results from research projects addressing these applications will be discussed: 1) an ultra-compact CO2 sensor based on a continuous wave quantum cascade laser, 2) an ultra-sensitive Faraday rotation spectrometer for O2 detection, 3) a fully ruggedized compact and low-power laser spectrometer, and 4) a novel non-paraxial nonthin multipass cell. Preliminary tests and projection for performance of future sensors based on this technology is presented.

Compacted dimensions and singular plasmonic surfaces

NASA Astrophysics Data System (ADS)

Pendry, J. B.; Huidobro, Paloma Arroyo; Luo, Yu; Galiffi, Emanuele

2017-11-01

In advanced field theories, there can be more than four dimensions to space, the excess dimensions described as compacted and unobservable on everyday length scales. We report a simple model, unconnected to field theory, for a compacted dimension realized in a metallic metasurface periodically structured in the form of a grating comprising a series of singularities. An extra dimension of the grating is hidden, and the surface plasmon excitations, though localized at the surface, are characterized by three wave vectors rather than the two of typical two-dimensional metal grating. We propose an experimental realization in a doped graphene layer.

The integrated design and archive of space-borne signal processing and compression coding

NASA Astrophysics Data System (ADS)

He, Qiang-min; Su, Hao-hang; Wu, Wen-bo

2017-10-01

With the increasing demand of users for the extraction of remote sensing image information, it is very urgent to significantly enhance the whole system's imaging quality and imaging ability by using the integrated design to achieve its compact structure, light quality and higher attitude maneuver ability. At this present stage, the remote sensing camera's video signal processing unit and image compression and coding unit are distributed in different devices. The volume, weight and consumption of these two units is relatively large, which unable to meet the requirements of the high mobility remote sensing camera. This paper according to the high mobility remote sensing camera's technical requirements, designs a kind of space-borne integrated signal processing and compression circuit by researching a variety of technologies, such as the high speed and high density analog-digital mixed PCB design, the embedded DSP technology and the image compression technology based on the special-purpose chips. This circuit lays a solid foundation for the research of the high mobility remote sensing camera.

Optical and X-ray studies of Compact X-ray Binaries in NGC 5904

NASA Astrophysics Data System (ADS)

Bhalotia, Vanshree; Beck-Winchatz, Bernhard

2018-06-01

Due to their high stellar densities, globular cluster systems trigger various dynamical interactions, such as the formation of compact X-ray binaries. Stellar collisional frequencies have been correlated to the number of X-ray sources detected in various clusters and we hope to measure this correlation for NGC 5904. Optical fluxes of sources from archival HST images of NGC 5904 have been measured using a DOLPHOT PSF photometry in the UV, optical and near-infrared. We developed a data analysis pipeline to process the fluxes of tens of thousands of objects using awk, python and DOLPHOT. We plot color magnitude diagrams in different photometric bands in order to identify outliers that could be X-ray binaries, since they do not evolve the same way as singular stars. Aligning previously measured astrometric data for X-ray sources in NGC 5904 from Chandra with archival astrometric data from HST will filter out the outlier objects that are not X-ray producing, and provide a sample of compact binary systems that are responsible for X-ray emission in NGC 5904. Furthermore, previously measured X-ray fluxes of NGC 5904 from Chandra have also been used to measure the X-ray to optical flux ratio and identify the types of compact X-ray binaries responsible for the X-ray emissions in NGC 5904. We gratefully acknowledge the support from the Illinois Space Grant Consortium.

Studies on space charge neutralization and emittance measurement of beam from microwave ion source.

PubMed

Misra, Anuraag; Goswami, A; Sing Babu, P; Srivastava, S; Pandit, V S

2015-11-01

A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

Studies on space charge neutralization and emittance measurement of beam from microwave ion source

NASA Astrophysics Data System (ADS)

Misra, Anuraag; Goswami, A.; Sing Babu, P.; Srivastava, S.; Pandit, V. S.

2015-11-01

A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (˜5 mA at 75 keV), it is possible to reduce the beam spot size by ˜34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

Building America Case Study: Compact Buried Ducts in a Hot-Humid Climate House, Lady's Island, South Carolina

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

2016-02-01

A system of compact, buried ducts provides a high-performance and cost-effective solution for delivering conditioned air throughout the building. This report outlines research activities that are expected to facilitate adoption of compact buried duct systems by builders. The results of this research would be scalable to many new house designs in most climates and markets, leading to wider industry acceptance and building code and energy program approval. The primary research question with buried ducts is potential condensation at the outer jacket of the duct insulation in humid climates during the cooling season. Current best practices for buried ducts rely onmore » encapsulating the insulated ducts with closed-cell spray polyurethane foam insulation to control condensation and improve air sealing. The encapsulated buried duct concept has been analyzed and shown to be effective in hot-humid climates. The purpose of this project is to develop an alternative buried duct system that performs effectively as ducts in conditioned space - durable, energy efficient, and cost-effective - in a hot-humid climate (IECC warm-humid climate zone 3A) with three goals that distinguish this project: 1) Evaluation of design criteria for buried ducts that use common materials and do not rely on encapsulation using spray foam or disrupt traditional work sequences, 2) Establishing design criteria for compact ducts and incorporate those with the buried duct criteria to further reduce energy losses and control installed costs, and 3) Developing HVAC design guidance for performing accurate heating and cooling load calculations for compact buried ducts.« less

Compact Buried Ducts in a Hot-Humid Climate House

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

Mallay, Dave

2016-01-07

"9A system of compact, buried ducts provides a high-performance and cost-effective solution for delivering conditioned air throughout the building. This report outlines research activities that are expected to facilitate adoption of compact buried duct systems by builders. The results of this research would be scalable to many new house designs in most climates and markets, leading to wider industry acceptance and building code and energy program approval. The primary research question with buried ducts is potential condensation at the outer jacket of the duct insulation in humid climates during the cooling season. Current best practices for buried ducts rely onmore » encapsulating the insulated ducts with closed-cell spray polyurethane foam insulation to control condensation and improve air sealing. The encapsulated buried duct concept has been analyzed and shown to be effective in hot-humid climates. The purpose of this project is to develop an alternative buried duct system that performs effectively as ducts in conditioned space - durable, energy efficient, and cost-effective - in a hot-humid climate (IECC warm-humid climate zone 3A) with three goals that distinguish this project: 1) Evaluation of design criteria for buried ducts that use common materials and do not rely on encapsulation using spray foam or disrupt traditional work sequences; 2) Establishing design criteria for compact ducts and incorporate those with the buried duct criteria to further reduce energy losses and control installed costs; 3) Developing HVAC design guidance for performing accurate heating and cooling load calculations for compact buried ducts.« less

Heavy-machinery traffic impacts methane emissions as well as methanogen abundance and community structure in oxic forest soils.

PubMed

Frey, Beat; Niklaus, Pascal A; Kremer, Johann; Lüscher, Peter; Zimmermann, Stephan

2011-09-01

Temperate forest soils are usually efficient sinks for the greenhouse gas methane, at least in the absence of significant amounts of methanogens. We demonstrate here that trafficking with heavy harvesting machines caused a large reduction in CH(4) consumption and even turned well-aerated forest soils into net methane sources. In addition to studying methane fluxes, we investigated the responses of methanogens after trafficking in two different forest sites. Trafficking generated wheel tracks with different impact (low, moderate, severe, and unaffected). We found that machine passes decreased the soils' macropore space and lowered hydraulic conductivities in wheel tracks. Severely compacted soils yielded high methanogenic abundance, as demonstrated by quantitative PCR analyses of methyl coenzyme M reductase (mcrA) genes, whereas these sequences were undetectable in unaffected soils. Even after a year after traffic compression, methanogen abundance in compacted soils did not decline, indicating a stability of methanogens here over time. Compacted wheel tracks exhibited a relatively constant community structure, since we found several persisting mcrA sequence types continuously present at all sampling times. Phylogenetic analysis revealed a rather large methanogen diversity in the compacted soil, and most mcrA gene sequences were mostly similar to known sequences from wetlands. The majority of mcrA gene sequences belonged either to the order Methanosarcinales or Methanomicrobiales, whereas both sites were dominated by members of the families Methanomicrobiaceae Fencluster, with similar sequences obtained from peatland environments. The results show that compacting wet forest soils by heavy machinery causes increases in methane production and release.

Prototype of a coherent tracking and detection receiver with wideband vibration compensation for free-space laser communications

NASA Astrophysics Data System (ADS)

Giggenbach, Dirk; Schex, Anton; Wandernoth, Bernhard

1996-04-01

The Optical Communications Group of the German Aerospace Research Establishment (DLR) has investigated the feasibility of a fiberless receiver telescope for high sensitive coherent optical space communication, resulting in an elegant pointing, acquisition and tracking (PAT) concept. To demonstrate the feasibility of this new concept, an optical receiver terminal that coherently obtains both the spatial error signal for tracking and the data signal with only one set of detectors has been built. The result is a very simple and compact setup with few optical surfaces. It does not require fibers for superpositioning and is capable to compensate for microaccelerations up to about one kilohertz.

MIC-Large Scale Magnetically Inflated Cable Structures for Space Power, Propulsion, Communications and Observational Applications

NASA Astrophysics Data System (ADS)

Powell, James; Maise, George; Rather, John

2010-01-01

A new approach for the erection of rigid large scale structures in space-MIC (Magnetically Inflated Cable)-is described. MIC structures are launched as a compact payload of superconducting cables and attached tethers. After reaching orbit, the superconducting cables are energized with electrical current. The magnet force interactions between the cables cause them to expand outwards into the final large structure. Various structural shapes and applications are described. The MIC structure can be a simple flat disc with a superconducting outer ring that supports a tether network holding a solar cell array, or it can form a curved mirror surface that concentrates light and focuses it on a smaller region-for example, a high flux solar array that generates electric power, a high temperature receiver that heats H2 propellant for high Isp propulsion, and a giant primary reflector for a telescope for astronomy and Earth surveillance. Linear dipole and quadrupole MIC structures are also possible. The linear quadrupole structure can be used for magnetic shielding against cosmic radiation for astronauts, for example. MIC could use lightweight YBCO superconducting HTS (High Temperature Superconductor) cables, that can operate with liquid N2 coolant at engineering current densities of ~105 amp/cm2. A 1 kilometer length of MIC cable would weigh only 3 metric tons, including superconductor, thermal insulations, coolant circuits, and refrigerator, and fit within a 3 cubic meter compact package for launch. Four potential MIC applications are described: Solar-thermal propulsion using H2 propellant, space based solar power generation for beaming power to Earth, a large space telescope, and solar electric generation for a manned lunar base. The first 3 applications use large MIC solar concentrating mirrors, while the 4th application uses a surface based array of solar cells on a magnetically levitated MIC structure to follow the sun. MIC space based mirrors can be very large and light in weight. A 300 meter diameter MIC mirror in orbit for example, would weigh 20 metric tons and MIC structures can be easily developed and tested on Earth at small scale in existing evacuated chambers followed by larger scale tests in the atmosphere, using a vacuum tight enclosure on the small diameter superconducting cable to prevent air leakage into the evacuated thermal insulation around the superconducting cable.

Effect of product form, compaction, vibration and comminution on energywood bulk density

Treesearch

Tim P. McDonald; Bryce J. Stokes; J.F. McNeel

1995-01-01

A study was performed to examine the changes in density of stacked roundwood, chips, and chunks as affected by various compaction treatments. Density of stacked roundwood bolts was tested for the effect of stacking orientation, binding of the stack ends, and species. Stacked bolt wood occupied less than 50 percent of the total rack space for all species, giving final...

On orthogonal projectors induced by compact groups and Haar measures

NASA Astrophysics Data System (ADS)

Niezgoda, Marek

2008-02-01

We study the difference of two orthogonal projectors induced by compact groups of linear operators acting on a vector space. An upper bound for the difference is derived using the Haar measures of the groups. A particular attention is paid to finite groups. Some applications are given for complex matrices and unitarily invariant norms. Majorization inequalities of Fan and Hoffmann and of Causey are rediscovered.

Spaceborne VHSIC multiprocessor system for AI applications

NASA Technical Reports Server (NTRS)

Lum, Henry, Jr.; Shrobe, Howard E.; Aspinall, John G.

1988-01-01

A multiprocessor system, under design for space-station applications, makes use of the latest generation symbolic processor and packaging technology. The result will be a compact, space-qualified system two to three orders of magnitude more powerful than present-day symbolic processing systems.

Spiral-path high-sensitivity silicon photonic wire molecular sensor with temperature-independent response.

PubMed

Densmore, A; Xu, D-X; Janz, S; Waldron, P; Mischki, T; Lopinski, G; Delâge, A; Lapointe, J; Cheben, P; Lamontagne, B; Schmid, J H

2008-03-15

We demonstrate a new silicon photonic wire waveguide evanescent field (PWEF) sensor that exploits the strong evanescent field of the transverse magnetic mode of this high-index-contrast, submicrometer-dimension waveguide. High sensitivity is achieved by using a 2 mm long double-spiral waveguide structure that fits within a compact circular area of 150 microm diameter, facilitating compatibility with commercial spotting apparatus and the fabrication of densely spaced sensor arrays. By incorporating the PWEF sensor element into a balanced waveguide Mach-Zehnder interferometer circuit, a minimum detectable mass of approximately 10 fg of streptavidin protein is demonstrated with near temperature-independent response.

Stability of gradient semigroups under perturbations

NASA Astrophysics Data System (ADS)

Aragão-Costa, E. R.; Caraballo, T.; Carvalho, A. N.; Langa, J. A.

2011-07-01

In this paper we prove that gradient-like semigroups (in the sense of Carvalho and Langa (2009 J. Diff. Eqns 246 2646-68)) are gradient semigroups (possess a Lyapunov function). This is primarily done to provide conditions under which gradient semigroups, in a general metric space, are stable under perturbation exploiting the known fact (see Carvalho and Langa (2009 J. Diff. Eqns 246 2646-68)) that gradient-like semigroups are stable under perturbation. The results presented here were motivated by the work carried out in Conley (1978 Isolated Invariant Sets and the Morse Index (CBMS Regional Conference Series in Mathematics vol 38) (RI: American Mathematical Society Providence)) for groups in compact metric spaces (see also Rybakowski (1987 The Homotopy Index and Partial Differential Equations (Universitext) (Berlin: Springer)) for the Morse decomposition of an invariant set for a semigroup on a compact metric space).

Turbo-Brayton cryocooler technology for low-temperature space applications

NASA Astrophysics Data System (ADS)

Zagarola, Mark V.; Breedlove, Jeffrey F.; McCormick, John A.; Swift, Walter L.

2003-03-01

High performance, low temperature cryocoolers are being developed for future space-borne telescopes and instruments. To meet mission objectives, these coolers must be compact, lightweight, have low input power, operate reliably for 5-10 years, and produce no disturbances that would affect the pointing accuracy of the instruments. This paper describes progress in the development of turbo-Brayton cryocoolers addressing cooling in the 5 K to 20 K temperature range for loads of up to 300 mW. The key components for these cryocoolers are the miniature, high-speed turbomachines and the high performance recuperative heat exchangers. The turbomachines use gas-bearings to support the low mass, high speed rotors, resulting in negligible vibration and long life. Precision fabrication techniques are used to produce the necessary micro-scale geometric features that provide for high cycle efficiencies at these reduced sizes. Turbo-Brayton cryocoolers for higher temperatures and loads have been successfully developed for space applications. For efficient operation at low temperatures and capacities, advances in the core technologies have been pursued. Performance test results of a new, low poer compressor will be presented, and early cryogenic test results on a low temperature expansion turbine will be discussed. Projections for several low temperature cooler configurations are summarized.

Potential for on-orbit manufacture of large space structures using the pultrusion process

NASA Technical Reports Server (NTRS)

Wilson, Maywood L.; Macconochie, Ian O.; Johnson, Gary S.

1987-01-01

On-orbit manufacture of lightweight, high-strength, advanced-composite structures using the pultrusion process is proposed. This process is adaptable to a zero-gravity environment by using preimpregnated graphite-fiber reinforcement systems. The reinforcement material is preimpregnated with a high-performance thermoplastic resin at a ground station, is coiled on spools for compact storage, and is transported into Earth orbit. A pultrusion machine is installed in the Shuttle cargo bay from which very long lengths of the desired structure is fabricated on-orbit. Potential structural profiles include rods, angles, channels, hat sections, tubes, honeycomb-cored panels, and T, H, and I beams. A potential pultrudable thermoplastic/graphite composite material is presented as a model for determining the effect on Earth-to-orbit package density of an on-orbit manufacture, the package density is increased by 132 percent, and payload volume requirement is decreased by 56.3 percent. The fabrication method has the potential for on-orbit manufacture of structural members for space platforms, large space antennas, and long tethers.

Mid-infrared optical frequency combs at 2.5 μm based on crystalline microresonators

PubMed Central

Wang, C. Y.; Herr, T.; Del’Haye, P.; Schliesser, A.; Hofer, J.; Holzwarth, R.; Hänsch, T. W.; Picqué, N.; Kippenberg, T. J.

2013-01-01

The mid-infrared spectral range (λ~2–20 μm) is of particular importance as many molecules exhibit strong vibrational fingerprints in this region. Optical frequency combs—broadband optical sources consisting of equally spaced and mutually coherent sharp lines—are creating new opportunities for advanced spectroscopy. Here we demonstrate a novel approach to create mid-infrared optical frequency combs via four-wave mixing in a continuous-wave pumped ultra-high Q crystalline microresonator made of magnesium fluoride. Careful choice of the resonator material and design made it possible to generate a broadband, low-phase noise Kerr comb at λ=2.5 μm spanning 200 nm (≈10 THz) with a line spacing of 100 GHz. With its distinguishing features of compactness, efficient conversion, large mode spacing and high power per comb line, this novel frequency comb source holds promise for new approaches to molecular spectroscopy and is suitable to be extended further into the mid-infrared. PMID:23299895

Development of miniature moving magnet cryocooler SX040

NASA Astrophysics Data System (ADS)

Rühlich, I.; Mai, M.; Rosenhagen, C.; Schreiter, A.; Möhl, C.

2011-06-01

State of the art high performance cooled IR systems need to have more than just excellent E/O performance. Minimum size weight and power (SWaP) are the design goals to meet our forces' mission requirements. Key enabler for minimum SWaP of IR imagers is the operation temperature of the focal plane array (FPA) employed. State of the art MCT or InAsSb nBn technology has the potential to rise the FPA temperature from 77 K to 130-150 K (high operation temperature HOT) depending on the specific cut-off wavelength. Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore compact high performance cryocoolers are mandatory. For highest MTTF life AIM developed its Flexure Bearing Moving Magnet product family "SF". Such coolers achieve more than 20000 h MTTF with Stirling type expander and more than 5 years MTTF life with Pulse Tube coldfinger (like for Space applications). To keep the high lifetime potential but to significantly improve SWaP AIM is developing its "SX" type cooler family. The new SX040 cooler incorporates a highly efficient dual piston Moving Magnet driving mechanism resulting in very compact compressor of less than 100mm length. The cooler's high lifetime is also achieved by placing the coils outside the helium vessel as usual for moving magnet motors. The mating ¼" expander is extremely compact with less than 63 mm length. This allows a total dewar length from optical window to expander warm end of less than 100 mm even for large cold shields. The cooler is optimized for HOT detectors with operating temperatures exceeding 95 K. While this kind of cooler is the perfect match for many applications, handheld sights or targeting devices for the dismounted soldier are even more challenging with respect to SWaP. AIM therefore started to develop an even smaller cooler type with single piston and balancer. This paper gives an overview on the development of this new compact cryocooler. Technical details and performance data will be shown.

Waste collection subsystem study

NASA Technical Reports Server (NTRS)

1984-01-01

Practical ways were explored of improving waste compaction and of providing rapid turnaround between flights at essentially no cost for the space shuttle waste collection subsystem commode. Because of the possible application of a fully developed shuttle commode to the space station, means of providing waste treatment without overboard venting were also considered. Three basic schemes for compaction and rapid turnaround, each fully capable of meeting the objectives, were explored in sufficient depth to bring out the characteristic advantages and disadvantages of each. Tradeoff comparisons were very close between leading contenders and efforts were made to refine the design concepts sufficiently to justify a selection. The concept selected makes use of a sealed canister containing wastes that have been forcibly compacted, which is removable in flight. No selection was made between three superior non-venting treatment methods owing to the need for experimental evaluations of the processes involved. A system requirements definition document has been prepared to define the task for a test embodiment of the selected concept.

On quantum symmetries of compact metric spaces

NASA Astrophysics Data System (ADS)

Chirvasitu, Alexandru

2015-08-01

An action of a compact quantum group on a compact metric space (X , d) is (D)-isometric if the distance function is preserved by a diagonal action on X × X. In this study, we show that an isometric action in this sense has the following additional property: the corresponding action on the algebra of continuous functions on X by the convolution semigroup of probability measures on the quantum group contracts Lipschitz constants. In other words, it is isometric in another sense due to Li, Quaegebeur, and Sabbe, which partially answers a question posed by Goswami. We also introduce other possible notions of isometric quantum actions in terms of the Wasserstein p-distances between probability measures on X for p ≥ 1, which are used extensively in optimal transportation. Indeed, all of these definitions of quantum isometry belong to a hierarchy of implications, where the two described above lie at the extreme ends of the hierarchy. We conjecture that they are all equivalent.

Innovative compact focal plane array for wide field vis and ir orbiting telescopes

NASA Astrophysics Data System (ADS)

Hugot, Emmanuel; Vives, Sébastien; Ferrari, Marc; Gaeremynck, Yann; Jahn, Wilfried

2017-11-01

The future generation of high angular resolution space telescopes will require breakthrough technologies to combine large diameters and large focal plane arrays with compactness and lightweight mirrors and structures. Considering the allocated volume medium-size launchers, short focal lengths are mandatory, implying complex optical relays to obtain diffraction limited images on large focal planes. In this paper we present preliminary studies to obtain compact focal plane arrays (FPA) for earth observations on low earth orbits at high angular resolution. Based on the principle of image slicers, we present an optical concept to arrange a 1D FPA into a 2D FPA, allowing the use of 2D detector matrices. This solution is particularly attractive for IR imaging requiring a cryostat, which volume could be considerably reduced as well as the relay optics complexity. Enabling the use of 2D matrices for such an application offers new possibilities. Recent developments on curved FPA allows optimization without concerns on the field curvature. This innovative approach also reduces the complexity of the telescope optical combination, specifically for fast telescopes. This paper will describe the concept and optical design of an F/5 - 1.5m telescope equipped with such a FPA, the performances and the impact on the system with a comparison with an equivalent 1.5m wide field Korsch telescope.

Space Vehicle Power System Comprised of Battery/Capacitor Combinations

NASA Technical Reports Server (NTRS)

Camarotte, C.; Lancaster, G. S.; Eichenberg, D.; Butler, S. M.; Miller, J. R.

2002-01-01

Recent improvements in energy densities of batteries open the possibility of using electric rather that hydraulic actuators in space vehicle systems. However, the systems usually require short-duration, high-power pulses. This power profile requires the battery system to be sized to meet the power requirements rather than stored energy requirements, often resulting in a large and inefficient energy storage system. Similar transient power applications have used a combination of two or more disparate energy storage technologies. For instance, placing a capacitor and a battery side-by-side combines the high energy density of a battery with the high power performance of a capacitor and thus can create a lighter and more compact system. A parametric study was performed to identify favorable scenarios for using capacitors. System designs were then carried out using equivalent circuit models developed for five commercial electrochemical capacitor products. Capacitors were sized to satisfy peak power levels and consequently "leveled" the power requirement of the battery, which can then be sized to meet system energy requirements. Simulation results clearly differentiate the performance offered by available capacitor products for the space vehicle applications.

MARTA: a high-energy cosmic-ray detector concept for high-accuracy muon measurement

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

Abreu, P.; Andringa, S.; Assis, P.

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. Here, the combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.

Development of a J-T Micro Compressor

NASA Astrophysics Data System (ADS)

Champagne, P.; Olson, J. R.; Nast, T.; Roth, E.; Collaco, A.; Kaldas, G.; Saito, E.; Loung, V.

2015-12-01

Lockheed Martin has developed and tested a space-quality compressor capable of delivering closed-loop gas flow with a high pressure ratio, suitable for driving a Joule- Thomson cold head. The compressor is based on a traditional “Oxford style” dual-opposed piston compressor with linear drive motors and flexure-bearing clearance-seal technology for high reliability and long life. This J-T compressor retains the approximate size, weight, and cost of the ultra-compact, 200 gram Lockheed Martin Pulse Tube Micro Compressor, despite the addition of a flow-rectifying system to convert the AC pressure wave into a steady flow.

Performance comparison of single and dual-excitation-wavelength resonance-Raman explosives detectors

NASA Astrophysics Data System (ADS)

Yellampalle, Balakishore; Martin, Robert; Witt, Kenneth; McCormick, William; Wu, Hai-Shan; Sluch, Mikhail; Ice, Robert; Lemoff, Brian

2017-05-01

Deep-ultraviolet Raman spectroscopy is a very useful approach for standoff detection of explosive traces. Using two simultaneous excitation wavelengths improves the specificity and sensitivity to standoff explosive detection. The High Technology Foundation developed a highly compact prototype of resonance Raman explosives detector. In this work, we discuss the relative performance of a dual-excitation sensor compared to a single-excitation sensor. We present trade space analysis comparing three representative Raman systems with similar size, weight, and power. The analysis takes into account, cost, spectral resolution, detection/identification time and the overall system benefit.

MARTA: a high-energy cosmic-ray detector concept for high-accuracy muon measurement

NASA Astrophysics Data System (ADS)

Abreu, P.; Andringa, S.; Assis, P.; Blanco, A.; Martins, V. Barbosa; Brogueira, P.; Carolino, N.; Cazon, L.; Cerda, M.; Cernicchiaro, G.; Colalillo, R.; Conceição, R.; Cunha, O.; de Almeida, R. M.; de Souza, V.; Diogo, F.; Dobrigkeit, C.; Espadanal, J.; Espirito-Santo, C.; Ferreira, M.; Ferreira, P.; Fonte, P.; Giaccari, U.; Gonçalves, P.; Guarino, F.; Lippmann, O. C.; Lopes, L.; Luz, R.; Maurizio, D.; Marujo, F.; Mazur, P.; Mendes, L.; Pereira, A.; Pimenta, Mario; Prado, R. R.; R̆ídký, J.; Sarmento, R.; Scarso, C.; Shellard, R.; Souza, J.; Tomé, B.; Trávníc̆ek, P.; Vícha, J.; Wolters, H.; Zas, E.

2018-04-01

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.

MARTA: a high-energy cosmic-ray detector concept for high-accuracy muon measurement

DOE PAGES

Abreu, P.; Andringa, S.; Assis, P.; ...

2018-04-24

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. Here, the combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.

Design approach for the development of a cryomodule for compact crab cavities for Hi-Lumi LHC

NASA Astrophysics Data System (ADS)

Pattalwar, Shrikant; Jones, Thomas; Templeton, Niklas; Goudket, Philippe; McIntosh, Peter; Wheelhouse, Alan; Burt, Graeme; Hall, Ben; Wright, Loren; Peterson, Tom

2014-01-01

A prototype Superconducting RF (SRF) cryomodule, comprising multiple compact crab cavities is foreseen to realise a local crab crossing scheme for the "Hi-Lumi LHC", a project launched by CERN to increase the luminosity performance of LHC. A cryomodule with two cavities will be initially installed and tested on the SPS drive accelerator at CERN to evaluate performance with high-intensity proton beams. A series of boundary conditions influence the design of the cryomodule prototype, arising from; the complexity of the cavity design, the requirement for multiple RF couplers, the close proximity to the second LHC beam pipe and the tight space constraints in the SPS and LHC tunnels. As a result, the design of the helium vessel and the cryomodule has become extremely challenging. This paper assesses some of the critical cryogenic and engineering design requirements and describes an optimised cryomodule solution for the evaluation tests on SPS.

Development of a Compact Eleven Feed Cryostat for the Patriot 12-m Antenna System

NASA Technical Reports Server (NTRS)

Beaudoin, Christopher; Kildal, Per-Simon; Yang, Jian; Pantaleev, Miroslav

2010-01-01

The Eleven antenna has constant beam width, constant phase center location, and low spillover over a decade bandwidth. Therefore, it can feed a reflector for high aperture efficiency (also called feed efficiency). It is equally important that the feed efficiency and its subefficiencies not be degraded significantly by installing the feed in a cryostat. The MIT Haystack Observatory, with guidance from Onsala Space Observatory and Chalmers University, has been working to integrate the Eleven antenna into a compact cryostat suitable for the Patriot 12-m antenna. Since the analysis of the feed efficiencies in this presentation is purely computational, we first demonstrate the validity of the computed results by comparing them to measurements. Subsequently, we analyze the dependence of the cryostat size on the feed efficiencies, and, lastly, the Patriot 12-m subreflector is incorporated into the computational model to assess the overall broadband efficiency of the antenna system.

Heat transfer and pressure drop in a compact pin-fin heat exchanger with pin orientation at 18 deg to the flow direction

NASA Technical Reports Server (NTRS)

Olson, D. A.

1991-01-01

The heat transfer and pressure drop characteristics of a novel, compact heat exchanger in helium gas were measured at 3.5 MPa and Reynolds numbers of 450 to 12,000. The pin-fin specimen consisted of pins, 0.51 mm high and spaced 2.03 mm on centers, spanning a channel through which the helium flows; the angle of the row of pins to the flow direction was 18 deg. The specimen was radiatively heated on the top side at heat fluxes up to 74 W/sq cm and insulated on the back side. Correlations were developed for the friction factor and Nusselt number. The Nusselt number compares favorably to those of past studies of staggered pin-fins, when the measured temperatures are extrapolated to the temperature of the wall-fluid interface.

Biomimetic small scale variable focal length lens unit using synthetic elastomer actuators

NASA Astrophysics Data System (ADS)

Kim, Baek-chul; Chung, Jinah; Lee, Y.; Nam, Jae-Do; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, J. C.

2011-04-01

Having a combination of a gel-like soft lens, ligaments, and the Ciliary muscles, the human eyes are effectively working for various focal lengths without a complicated group of lens. The simple and compact but effective optical system should deserve numerous attentions from various technical field especially portable information technology device industry. Noting the limited physical space of those deivces, demanding shock durability, and massive volume productivity, the present paper proposes a biomimetic optical lens unit that is organized with a circular silicone lens and an annular dielectric polymer actuator. Unlike the traditional optical lens mechanism that normally acquires a focus by changing its focal distance with moving lens or focal plane. the proposed optical system changes its lens thickness using a annulary connected polymer actuator in order to get image focuses. The proposed biomimetic lens system ensures high shock durability, compact physical dimensions, fast actuations, simple manufacturing process, and low production cost.

A new compact representation of morphological profiles: report on first massive VHR image processing at the JRC

NASA Astrophysics Data System (ADS)

Pesaresi, Martino; Ouzounis, Georgios K.; Gueguen, Lionel

2012-06-01

A new compact representation of dierential morphological prole (DMP) vector elds is presented. It is referred to as the CSL model and is conceived to radically reduce the dimensionality of the DMP descriptors. The model maps three characteristic parameters, namely scale, saliency and level, into the RGB space through a HSV transform. The result is a a medium abstraction semantic layer used for visual exploration, image information mining and pattern classication. Fused with the PANTEX built-up presence index, the CSL model converges to an approximate building footprint representation layer in which color represents building class labels. This process is demonstrated on the rst high resolution (HR) global human settlement layer (GHSL) computed from multi-modal HR and VHR satellite images. Results of the rst massive processing exercise involving several thousands of scenes around the globe are reported along with validation gures.

Numerical simulation of magnetic field for compact electromagnet consisting of REBCO coils and iron yoke

NASA Astrophysics Data System (ADS)

You, Shuangrong; Chi, Changxin; Guo, Yanqun; Bai, Chuanyi; Liu, Zhiyong; Lu, Yuming; Cai, Chuanbing

2018-07-01

This paper presents the numerical simulation of a high-temperature superconductor electromagnet consisting of REBCO (RE-Ba2Cu3O7‑x, RE: rare earth) superconducting tapes and a ferromagnetic iron yoke. The REBCO coils with multi-width design are operating at 77 K, with the iron yoke at room temperature, providing a magnetic space with a 32 mm gap between two poles. The finite element method is applied to compute the 3D model of the studied magnet. Simulated results show that the magnet generates a 1.5 T magnetic field at an operating current of 38.7 A, and the spatial inhomogeneity of the field is 0.8% in a Φ–20 mm diameter sphere volume. Compared with the conventional iron electromagnet, the present compact design is more suitable for practical application.

A structural investigation into the compaction behavior of pharmaceutical composites using powder X-ray diffraction and total scattering analysis.

PubMed

Moore, Michael D; Steinbach, Alison M; Buckner, Ira S; Wildfong, Peter L D

2009-11-01

To use advanced powder X-ray diffraction (PXRD) to characterize the structure of anhydrous theophylline following compaction, alone, and as part of a binary mixture with either alpha-lactose monohydrate or microcrystalline cellulose. Compacts formed from (1) pure theophylline and (2) each type of binary mixture were analyzed intact using PXRD. A novel mathematical technique was used to accurately separate multi-component diffraction patterns. The pair distribution function (PDF) of isolated theophylline diffraction data was employed to assess structural differences induced by consolidation and evaluated by principal components analysis (PCA). Changes induced in PXRD patterns by increasing compaction pressure were amplified by the PDF. Simulated data suggest PDF dampening is attributable to molecular deviations from average crystalline position. Samples compacted at different pressures were identified and differentiated using PCA. Samples compacted at common pressures exhibited similar inter-atomic correlations, where excipient concentration factored in the analyses involving lactose. Practical real-space structural analysis of PXRD data by PDF was accomplished for intact, compacted crystalline drug with and without excipient. PCA was used to compare multiple PDFs and successfully differentiated pattern changes consistent with compaction-induced disordering of theophylline as a single component and in the presence of another material.

Compact optics for high resolution spectroscopy of celestial x-ray sources

NASA Astrophysics Data System (ADS)

Cash, W.; Lillie, C.; McEntaffer, R.; Zhang, W.

2011-05-01

The astronomy community has never flown a celestial source spectrograph that can resolve natural line widths in absorption the way the ultraviolet community since OAO-3 Copernicus in 1972. Yet there is important science to be mined there, and right now there are now missions on track to pursue it. We present a modified off-plane grating spectrograph design that will support high resolution (λ/δλ ~ 4000) in the soft x-ray band with a high packing density that will enable a modest cost space mission. We discuss the design for the WHIMEx mission which was proposed as an Explorer earlier this year with the goal of detecting high temperature oxygen in the Intergalactic Medium.

Nuclear Power in Space.

ERIC Educational Resources Information Center

Department of Energy, Washington, DC. Nuclear Energy Office.

Research has shown that nuclear radioisotope power generators can supply compact, reliable, and efficient sources of energy for a broad range of space missions. These missions range from televising views of planetary surfaces to communicating scientific data to Earth. This publication presents many applications of the advancing technology and…

Lunar Ice Cube: Development of a Deep Space Cubesat Mission

NASA Astrophysics Data System (ADS)

Clark, P. E.; Malphrus, B.; McElroy, D.; Schabert, J.; Wilczewski, S.; Farrell, W.; Brambora, C.; Macdowall, R.; Folta, D.; Hurford, T.; Patel, D.; Banks, S.; Reuter, D.; Brown, K.; Angkasa, K.; Tsay, M.

2017-10-01

Lunar Ice Cube, a 6U deep space cubesat mission, will be deployed by EM1. It will demonstrate cubesat propulsion, the Busek BIT 3 RF Ion engine, and a compact instrument capable of addressing HEOMD Strategic Knowledge Gaps related to lunar volatiles.

A new class of compact high sensitive tiltmeter based on the UNISA folded pendulum mechanical architecture

NASA Astrophysics Data System (ADS)

Barone, Fabrizio; Giordano, Gerardo

2018-02-01

We present the Extended Folded Pendulum Model (EFPM), a model developed for a quantitative description of the dynamical behavior of a folded pendulum generically oriented in space. This model, based on the Tait-Bryan angular reference system, highlights the relationship between the folded pendulum orientation in the gravitational field and its natural resonance frequency. Tis model validated by tests performed with a monolithic UNISA Folded Pendulum, highlights a new technique of implementation of folded pendulum based tiltmeters.

Compact antenna arrays with wide bandwidth and low sidelobe levels

DOEpatents

Strassner, II, Bernd H.

2014-09-09

Highly efficient, low cost, easily manufactured SAR antenna arrays with lightweight low profiles, large instantaneous bandwidths and low SLL are disclosed. The array topology provides all necessary circuitry within the available antenna aperture space and between the layers of material that comprise the aperture. Bandwidths of 15.2 GHz to 18.2 GHz, with 30 dB SLLs azimuthally and elevationally, and radiation efficiencies above 40% may be achieved. Operation over much larger bandwidths is possible as well.

Piping Connector

NASA Technical Reports Server (NTRS)

1994-01-01

In Stennis Space Center's Component Test Facility, piping lines carry rocket propellants and high pressure cryogenic fuels. When the lines are chilled to a pretest temperature of 400 degrees below zero, ordinary piping connectors can leak. Under contract to Stennis, Reflange, Inc. developed the T-Con connector, which included a secondary seal that tolerates severe temperature change. Because of the limited need for the large and expensive T-Con product, Reflange also developed the less costly E-Con, a smaller more compact design with the same technical advantages as the T-Con.

Compaction of Space Mission Wastes

NASA Technical Reports Server (NTRS)

Fisher, John; Pisharody, Suresh; Wignarajah, K.

2004-01-01

The current solid waste management system employed on the International Space Station (ISS) consists of compaction, storage, and disposal. Wastes such plastic food packaging and trash are compacted manually and wrapped in duct tape footballs by the astronauts. Much of the waste is simply loaded either into the empty Russian Progress vehicle for destruction on reentry or into Shuttle for return to Earth. This manual method is wasteful of crew time and does not transition well to far term missions. Different wastes onboard spacecraft vary considerably in their characteristics and in the appropriate method of management. In advanced life support systems for far term missions, recovery of resources such as water from the wastes becomes important. However waste such as plastic food packaging, which constitutes a large fraction of solid waste (roughly 21% on ISS, more on long duration missions), contains minimal recoverable resource. The appropriate management of plastic waste is waste stabilization and volume minimization rather than resource recovery. This paper describes work that has begun at Ames Research Center on development of a heat melt compactor that can be used on near term and future missions, that can minimize crew interaction, and that can handle wastes with a significant plastic composition. The heat melt compactor takes advantage of the low melting point of plastics to compact plastic materials using a combination of heat and pressure. The US Navy has demonstrated successful development of a similar unit for shipboard application. Ames is building upon the basic approach demonstrated by the Navy to develop an advanced heat melt type compactor for space mission type wastes.

Stabilization of a locally minimal forest

NASA Astrophysics Data System (ADS)

Ivanov, A. O.; Mel'nikova, A. E.; Tuzhilin, A. A.

2014-03-01

The method of partial stabilization of locally minimal networks, which was invented by Ivanov and Tuzhilin to construct examples of shortest trees with given topology, is developed. According to this method, boundary vertices of degree 2 are not added to all edges of the original locally minimal tree, but only to some of them. The problem of partial stabilization of locally minimal trees in a finite-dimensional Euclidean space is solved completely in the paper, that is, without any restrictions imposed on the number of edges remaining free of subdivision. A criterion for the realizability of such stabilization is established. In addition, the general problem of searching for the shortest forest connecting a finite family of boundary compact sets in an arbitrary metric space is formalized; it is shown that such forests exist for any family of compact sets if and only if for any finite subset of the ambient space there exists a shortest tree connecting it. The theory developed here allows us to establish further generalizations of the stabilization theorem both for arbitrary metric spaces and for metric spaces with some special properties. Bibliography: 10 titles.

Compact Water Vapor Exchanger for Regenerative Life Support Systems

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Anderson, Molly; Hodgson, Edward

2012-01-01

Thermal and environmental control systems for future exploration spacecraft must meet challenging requirements for efficient operation and conservation of resources. Regenerative CO2 removal systems are attractive for these missions because they do not use consumable CO2 absorbers. However, these systems also absorb and vent water to space along with carbon dioxide. This paper describes an innovative device designed to minimize water lost from regenerative CO2 control systems. Design studies and proof-of-concept testing have shown the feasibility of a compact, efficient membrane water vapor exchanger (WVX) that will conserve water while meeting challenging requirements for operation on future spacecraft. Compared to conventional WVX designs, the innovative membrane WVX described here has the potential for high water recovery efficiency, compact size, and very low pressure losses. The key innovation is a method for maintaining highly uniform flow channels in a WVX core built from water-permeable membranes. The proof-of-concept WVX incorporates all the key design features of a prototypical unit, except that it is relatively small scale (1/23 relative to a unit sized for a crew of six) and some components were fabricated using non-prototypical methods. The proof-of-concept WVX achieved over 90% water recovery efficiency in a compact core in good agreement with analysis models. Furthermore the overall pressure drop is very small (less than 0.5 in. H2O, total for both flow streams) and meets requirements for service in environmental control and life support systems on future spacecraft. These results show that the WVX provides very uniform flow through flow channels for both the humid and dry streams. Measurements also show that CO2 diffusion through the water-permeable membranes will have negligible effect on the CO2 partial pressure in the spacecraft atmosphere.

Development of a Compact, Pulsed, 2-Micron, Coherent-Detection, Doppler Wind Lidar Transceiver; and Plans for Flights on NASA's DC-8 and WB-57 Aircraft

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Singh, Upendra N.; Koch, Grady J.; Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Petzar, Paul J.

2009-01-01

We present results of a recently completed effort to design, fabricate, and demonstrate a compact lidar transceiver for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to permit study of the laser technology currently envisioned by NASA for global coherent Doppler lidar measurement of winds in the future. The 250 mJ, 10 Hz compact transceiver was also designed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 and WB-57 aircraft. The WB-57 flights will present a more severe environment and will require autonomous operation of the lidar system. The DC-8 lidar system is a likely component of future NASA hurricane research. It will include real-time data processing and display, as well as full data archiving. We will attempt to co-fly on both aircraft with a direct-detection Doppler wind lidar system being prepared by NASA Goddard Space Flight Center.

Compact Infrasonic Windscreen

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Shams, Qamar A.; Sealey, Bradley S.; Comeaux, Toby

2005-01-01

A compact windscreen has been conceived for a microphone of a type used outdoors to detect atmospheric infrasound from a variety of natural and manmade sources. Wind at the microphone site contaminates received infrasonic signals (defined here as sounds having frequencies <20 Hz), because a microphone cannot distinguish between infrasonic pressures (which propagate at the speed of sound) and convective pressure fluctuations generated by wind turbulence. Hence, success in measurement of outdoor infrasound depends on effective screening of the microphone from the wind. The present compact windscreen is based on a principle: that infrasound at sufficiently large wavelength can penetrate any barrier of practical thickness. Thus, a windscreen having solid, non-porous walls can block convected pressure fluctuations from the wind while transmitting infrasonic acoustic waves. The transmission coefficient depends strongly upon the ratio between the acoustic impedance of the windscreen and that of air. Several materials have been found to have impedance ratios that render them suitable for use in constructing walls that have practical thicknesses and are capable of high transmission of infrasound. These materials (with their impedance ratios in parentheses) are polyurethane foam (222), space shuttle tile material (332), balsa (323), cedar (3,151), and pine (4,713).

Compact, passively Q-switched Nd:YAG laser for the MESSENGER mission to Mercury.

PubMed

Krebs, Danny J; Novo-Gradac, Anne-Marie; Li, Steven X; Lindauer, Steven J; Afzal, Robert S; Yu, Anthony W

2005-03-20

A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instrument, and satellite integration testing and successfully completes a postlaunch aliveness check en route to Mercury. The laser design draws on a heritage of previous laser altimetry missions, specifically the Ice Cloud and Elevation Satellite and the Mars Global Surveyor, but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

Resolution of massive compact clusters in the 30 Doradus periphery with the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Walborn, Nolan R.; Mackenty, John W.; Saha, Abhijit; White, Richard L.; Parker, Joel WM.

1995-01-01

Hubble Space Telescope Wide Field/Planetary Camera UBV images of three massive, compact multiple systems with the SNR 30 Dor B/NGC 2060 and 30 Dor C/NGC 2044 are discussed and illustrated. In two cases, WN+OB objects have been resolved into additional components to those previously known from ground-based observations, substantially reducing the luminosities of the WN stars and rendering them currently unidentified; in the third case, the components of a B+K composite-spectrum object have been clearly identified. The results are of significance for evolutionary interpretations of these massive stars and for determinations of the upper IMF in extragalactic systems.

Pluripotential theory and convex bodies

NASA Astrophysics Data System (ADS)

Bayraktar, T.; Bloom, T.; Levenberg, N.

2018-03-01

A seminal paper by Berman and Boucksom exploited ideas from complex geometry to analyze the asymptotics of spaces of holomorphic sections of tensor powers of certain line bundles L over compact, complex manifolds as the power grows. This yielded results on weighted polynomial spaces in weighted pluripotential theory in {C}^d. Here, motivated by a recent paper by the first author on random sparse polynomials, we work in the setting of weighted pluripotential theory arising from polynomials associated to a convex body in ({R}^+)^d. These classes of polynomials need not occur as sections of tensor powers of a line bundle L over a compact, complex manifold. We follow the approach of Berman and Boucksom to obtain analogous results. Bibliography: 16 titles.

Non-compact nonlinear sigma models

DOE PAGES

de Rham, Claudia; Tolley, Andrew J.; Zhou, Shuang-Yong

2016-07-19

The target space of a nonlinear sigma model is usually required to be positive definite to avoid ghosts. We introduce a unique class of nonlinear sigma models where the target space metric has a Lorentzian signature, thus the associated group being non-compact. We show that the would-be ghost associated with the negative direction is fully projected out by 2 second-class constraints, and there exist stable solutions in this class of models. This result also has important implications for Lorentz–invariant massive gravity: There exist stable nontrivial vacua in massive gravity that are free from any linear vDVZ-discontinuity and a decoupling limitmore » can be defined on these vacua.« less

Non-compact nonlinear sigma models

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

de Rham, Claudia; Tolley, Andrew J.; Zhou, Shuang-Yong

The target space of a nonlinear sigma model is usually required to be positive definite to avoid ghosts. We introduce a unique class of nonlinear sigma models where the target space metric has a Lorentzian signature, thus the associated group being non-compact. We show that the would-be ghost associated with the negative direction is fully projected out by 2 second-class constraints, and there exist stable solutions in this class of models. This result also has important implications for Lorentz–invariant massive gravity: There exist stable nontrivial vacua in massive gravity that are free from any linear vDVZ-discontinuity and a decoupling limitmore » can be defined on these vacua.« less

Heat Melt Compaction as an Effective Treatment for Eliminating Microorganisms from Solid Waste

NASA Technical Reports Server (NTRS)

Hummerick, Mary P.; Strayer, Richard F.; McCoy, Lashelle E.; Richards, Jeffrey T.; Ruby, Anna Maria; Wheeler, Ray; Fisher, John

2013-01-01

One of the technologies being tested at Ames Research Center as part of the logistics and repurposing project is heat melt compaction (HMC) of solid waste to reduce volume, remove water and render a biologically stable and safe product. Studies at Kennedy Space Center have focused on the efficacy of the heat melt compaction process for killing microorganisms in waste and specific compacter operation protocols, i.e., time and temperature required to achieve a sterile, stable product. The work. reported here includes a controlled study to examine the survival and potential re-growth of specific microorganisms over a 6-month period of storage after heating and compaction. Before heating and compaction, ersatz solid wastes were inoculated with Bacillus amyloliquefaciens and Rhodotorula mucilaginosa, previously isolated from recovered space shuttle mission food and packaging waste. Compacted HMC tiles were sampled for microbiological analysis at time points between 0 and 180 days of storage in a controlled environment chamber. In addition, biological indicator strips containing spores of Bacillus atrophaeus and Geobacillus stearothermophilus were imbedded in trash to assess the efficacy of the HMC process to achieve sterilization. Analysis of several tiles compacted at 180deg C for times of 40 minutes to over 2 hours detected organisms in all tile samples with the exception of one exposed to 180deg C for approximately 2 hours. Neither of the inoculated organisms was recovered, and the biological indicator strips were negative for growth in all tiles indicating at least local sterilization of tile areas. The findings suggest that minimum time/temperature combination is required for complete sterilization. Microbial analysis of tiles processed at lower temperatures from 130deg C-150deg C at varying times will be discussed, as well as analysis of the bacteria and fungi present on the compactor hardware as a result of exposure to the waste and the surrounding environment. The two organisms inoculated into the waste were among those isolated and identified from the HMC surfaces indicating the possibility of cross contamination.

The effect of mulching and soil compaction on fungi composition and microbial communities in the rhizosphere of soybean

NASA Astrophysics Data System (ADS)

Frac, M.; Siczek, A.; Lipiec, J.

2009-04-01

The soil environment is the habitat of pathogenic and saprotrophic microorganisms. The composition of the microbial community are related to biotic and abiotic factors, such as root exudates, crop residues, climate factors, mulching, mineral fertilization, pesticides introduction and soil compaction. The aim of the study was to determine the effect of the mulching and soil compaction on the microorganism communities in the rhizosphere soil of soybean. The studies were carried out on silty loam soil (Orthic Luvisol) developed from loess (Lublin, Poland). The experiment area was 192m2 divided into 3 sections consisted of 6 micro-plots (7m2). Three levels of soil compaction low, medium and heavy obtained through tractor passes were compared. The soil was compacted and loosened within seedbed layer 2 weeks before sowing. Soybean "Aldana" seeds were inoculated with Bradyrhizobium japonicum and were sown with interrow spacing of 0.3m. Wheat straw (as mulch) was uniformly spread on the half of each micro-plot at an amount of 0.5kg m-1 after sowing. Rhizosphere was collected three times during growing season of soybean. Microbiological analyses were conducted in 3 replications and included the determination of: the total number of bacteria and fungi, the number of bacteria Pseudomonas sp. and Bacillus sp., the genus identification of fungi isolated from rhizosphere of soybean. Results indicated a positive effect of mulching on the increase number of all groups of examined rhizosphere microorganisms (fungi, bacteria, Pseudomonas sp., Bacillus sp.). The highest number of the microorganisms was found in the low and medium compacted soil and markedly decreased in the most compacted soil. Relatively high number of antagonistic fungi (Penicillium sp., Trichoderma sp.) was recorded in the rhizosphere of low and medium compacted soil, particularly in mulched plots. The presence of these fungi can testify to considerable biological activity, which contributes to the improvement of the phytosanitary condition of the soil. However, the decrease of the antagonistic microorganism number in the heavy compacted soil can be responsible for appearance higher number of the potentially phytopathogenic fungi (Fusarium sp., Phoma sp.). Further research, with using molecular technique, will help better understanding interactions between plant and microorganisms in the soybean rhizosphere under different soil management conditions.

Compacted dimensions and singular plasmonic surfaces.

PubMed

Pendry, J B; Huidobro, Paloma Arroyo; Luo, Yu; Galiffi, Emanuele

2017-11-17

In advanced field theories, there can be more than four dimensions to space, the excess dimensions described as compacted and unobservable on everyday length scales. We report a simple model, unconnected to field theory, for a compacted dimension realized in a metallic metasurface periodically structured in the form of a grating comprising a series of singularities. An extra dimension of the grating is hidden, and the surface plasmon excitations, though localized at the surface, are characterized by three wave vectors rather than the two of typical two-dimensional metal grating. We propose an experimental realization in a doped graphene layer. Copyright © 2017, American Association for the Advancement of Science.

Comparative study of standard space and real space analysis of quantitative MR brain data.

PubMed

Aribisala, Benjamin S; He, Jiabao; Blamire, Andrew M

2011-06-01

To compare the robustness of region of interest (ROI) analysis of magnetic resonance imaging (MRI) brain data in real space with analysis in standard space and to test the hypothesis that standard space image analysis introduces more partial volume effect errors compared to analysis of the same dataset in real space. Twenty healthy adults with no history or evidence of neurological diseases were recruited; high-resolution T(1)-weighted, quantitative T(1), and B(0) field-map measurements were collected. Algorithms were implemented to perform analysis in real and standard space and used to apply a simple standard ROI template to quantitative T(1) datasets. Regional relaxation values and histograms for both gray and white matter tissues classes were then extracted and compared. Regional mean T(1) values for both gray and white matter were significantly lower using real space compared to standard space analysis. Additionally, regional T(1) histograms were more compact in real space, with smaller right-sided tails indicating lower partial volume errors compared to standard space analysis. Standard space analysis of quantitative MRI brain data introduces more partial volume effect errors biasing the analysis of quantitative data compared to analysis of the same dataset in real space. Copyright © 2011 Wiley-Liss, Inc.

Development of a Compact, Efficient Cooling Pump for Space Suit Life Support Systems

NASA Technical Reports Server (NTRS)

van Boeyen, Roger; Reeh, Jonathan; Trevino, Luis

2009-01-01

A compact, low-power electrochemically-driven fluid cooling pump is currently being developed by Lynntech, Inc. With no electric motor and minimal lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness is achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit primary life support systems (PLSSs). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops is discussed.

New functionalities of potassium tantalate niobate deflectors enabled by the coexistence of pre-injected space charge and composition gradient

NASA Astrophysics Data System (ADS)

Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Campbell, Adrian L.; Henry, Michael G.; Yin, Stuart Shizhuo; Hoffman, Robert C.

2017-10-01

In most beam steering applications such as 3D printing and in vivo imaging, one of the essential challenges has been high-resolution high-speed multi-dimensional optical beam scanning. Although the pre-injected space charge controlled potassium tantalate niobate (KTN) deflectors can achieve speeds in the nanosecond regime, they deflect in only one dimension. In order to develop a high-resolution high-speed multi-dimensional KTN deflector, we studied the deflection behavior of KTN deflectors in the case of coexisting pre-injected space charge and composition gradient. We find that such coexistence can enable new functionalities of KTN crystal based electro-optic deflectors. When the direction of the composition gradient is parallel to the direction of the external electric field, the zero-deflection position can be shifted, which can reduce the internal electric field induced beam distortion, and thus enhance the resolution. When the direction of the composition gradient is perpendicular to the direction of the external electric field, two-dimensional beam scanning can be achieved by harnessing only one single piece of KTN crystal, which can result in a compact, high-speed two-dimensional deflector. Both theoretical analyses and experiments are conducted, which are consistent with each other. These new functionalities can expedite the usage of KTN deflection in many applications such as high-speed 3D printing, high-speed, high-resolution imaging, and free space broadband optical communication.

Multifidelity, multidisciplinary optimization of turbomachines with shock interaction

NASA Astrophysics Data System (ADS)

Joly, Michael Marie

Research on high-speed air-breathing propulsion aims at developing aircraft with antipodal range and space access. Before reaching high speed at high altitude, the flight vehicle needs to accelerate from takeoff to scramjet takeover. Air turbo rocket engines combine turbojet and rocket engine cycles to provide the necessary thrust in the so-called low-speed regime. Challenges related to turbomachinery components are multidisciplinary, since both the high compression ratio compressor and the powering high-pressure turbine operate in the transonic regime in compact environments with strong shock interactions. Besides, lightweight is vital to avoid hindering the scramjet operation. Recent progress in evolutionary computing provides aerospace engineers with robust and efficient optimization algorithms to address concurrent objectives. The present work investigates Multidisciplinary Design Optimization (MDO) of innovative transonic turbomachinery components. Inter-stage aerodynamic shock interaction in turbomachines are known to generate high-cycle fatigue on the rotor blades compromising their structural integrity. A soft-computing strategy is proposed to mitigate the vane downstream distortion, and shown to successfully attenuate the unsteady forcing on the rotor of a high-pressure turbine. Counter-rotation offers promising prospects to reduce the weight of the machine, with fewer stages and increased load per row. An integrated approach based on increasing level of fidelity and aero-structural coupling is then presented and allows achieving a highly loaded compact counter-rotating compressor.

MIC: Magnetically Deployable Structures for Power, Propulsion, Processing, Habitats and Energy Storage at Manned Lunar Bases

NASA Astrophysics Data System (ADS)

Powell, James; Maise, George; Paniagua, John; Rather, John

2007-01-01

MIC (Magnetically Inflated Cables) is a new approach for robotically erecting very large, strong, rigid, and ultra-lightweight structures in space. MIC structures use a network of high current (SC) cables with attached high tensile strength Kevlar or Spectra tethers. MIC is launched as a compact package of coiled SC cables and tethers on a conventional launch vehicle. Once in space the SC cables are electrically energized. The resultant strong outwards magnetic forces expand them and the restraining tethers into a large structure, which can be 100's of meters in size. MIC structures can be configured for many different applications, including solar electric generation, solar thermal propulsion, energy storage, large space telescopes, magnetic shielding for astronauts, etc. The MIC technology components, including high temperature superconductors (HTS), thermal insulation, high strength tethers, and cryogenic refrigerators all exist commercially. Refrigeration requirements are very modest, on the order of 100 watts thermal per kilometer of MIC cable, with an input electric power to the refrigeration system of ~5 kW(e) per km. baseline MIC designs are described for a manned lunar base, including: 1) a 1 MW(e) solar electric system, 2) a high Isp (~900 seconds) solar thermal tug to transport 30 ton payloads between the Earth and the Moon, 3) a 2000 Megajoule electric energy storage system for peaking and emergency power, and 4) a large (~1 km) space telescope.

A Compact L-band Radiometer for High Resolution sUAS-based Imaging of Soil Moisture and Surface Salinity Variations

NASA Astrophysics Data System (ADS)

Gasiewski, A. J.; Stachura, M.; Dai, E.; Elston, J.; McIntyre, E.; Leuski, V.

2014-12-01

Due to the long electrical wavelengths required along with practical aperture size limitations the scaling of passive microwave remote sensing of soil moisture and salinity from spaceborne low-resolution (~10-100 km) applications to high resolution (~10-1000 m) applications requires use of low flying aerial vehicles. This presentation summarizes the status of a project to develop a commercial small Unmanned Aerial System (sUAS) hosting a microwave radiometer for mapping of soil moisture in precision agriculture and sea surface salinity studies. The project is based on the Tempest electric-powered UAS and a compact L-band (1400-1427 MHz) radiometer developed specifically for extremely small and lightweight aerial platforms or man-portable, tractor, or tower-based applications. Notable in this combination are a highly integrated sUAS/radiometer antenna design and use of both the upwelling emitted signal from the surface and downwelling cold space signal for precise calibration using a unique lobe-differencing correlating radiometer architecture. The system achieves a spatial resolution comparable to the altitude of the UAS above the surface while referencing upwelling measurements to the constant and well-known background temperature of cold space. The radiometer has been tested using analog correlation detection, although future builds will include infrared, near-infrared, and visible (red) sensors for surface temperature and vegetation biomass correction and digital sampling for radio frequency interference mitigation. This NASA-sponsored project is being developed for commercial application in cropland water management (for example, high-value shallow root-zone crops), landslide risk assessment, NASA SMAP satellite validation, and NASA Aquarius salinity stratification studies. The system will ultimately be capable of observing salinity events caused by coastal glacier and estuary fresh water outflow plumes and open ocean rainfall events.

Mini-EUSO: A Precursor Mission on the International Space Station for the Observation of Atmosphere and Earth in the UV Light

NASA Astrophysics Data System (ADS)

Ricci, Marco

For any experiment aiming at the observation of Ultra High Energy Cosmic Rays (UHECRs) from space, one key measurement is related to the UV emissions produced in the Earth's atmosphere. In view of the planned missions under study (KLYPVE-EUSO, JEM-EUSO, EUSO-FF) at the International Space Station (ISS) and on board of free-flyer satellites, a small, compact UV telescope, Mini-EUSO, is being developed by the JEM-EUSO International Collaboration to be placed at the UV-transparent, nadir looking window of the Russian module of the ISS. In addition to the main purpose of mapping the Earth in the UV range (300-400 nm), Mini-EUSO will also perform studies of atmospheric phenomena, observation of meteors, strange quark matter search and space debris tracking. It will as well enhance the technological readiness level of the EUSO concept and instruments. Mini-EUSO is a mission approved and selected by the Italian Space Agency (ASI) and, under the name "UV atmosphere", by the Russian Space Agency Roscosmos.

A LYSO crystal array readout by silicon photomultipliers as compact detector for space applications

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

Kryemadhi, A.; Barner, L.; Grove, A.

Precise measurements of GeV range gamma rays help narrow down among var- ious gamma emission models and increase sensitivity for dark matter searches. Construction of precise as well as compact instruments requires detectors with high efficiency, high stopping power, excellent energy resolution, and excellent angular resolution. Fast and bright crystal scintillators coupled with small foot- print photo-detectors are suitable candidates. We prototyped a detector array consisting of four LYSO crystals where each crystal is read out by a 2x2 SensL ArrayJ60035 silicon photomultipliers. The LYSO crystals were chosen because of their good light yield, fast decay time, demonstrated radiation hardness,more » and small radiation length. Here, we used the silicon photomultiplier arrays as photo- detectors because of their small size, simple readout, low voltage operation, and immunity to magnetic elds. We also studied the detector performance in the energy range of interest by exposing it to 2-16 GeV particles produced at the Test Beam Facility of Fermi National Accelerator Laboratory.« less

Silicon carbide transparent chips for compact atomic sensors

NASA Astrophysics Data System (ADS)

Huet, L.; Ammar, M.; Morvan, E.; Sarazin, N.; Pocholle, J.-P.; Reichel, J.; Guerlin, C.; Schwartz, S.

2017-11-01

Atom chips [1] are an efficient tool for trapping, cooling and manipulating cold atoms, which could open the way to a new generation of compact atomic sensors addressing space applications. This is in particular due to the fact that they can achieve strong magnetic field gradients near the chip surface, hence strong atomic confinement at moderate electrical power. However, this advantage usually comes at the price of reducing the optical access to the atoms, which are confined very close to the chip surface. We will report at the conference experimental investigations showing how these limits could be pushed farther by using an atom chip made of a gold microcircuit deposited on a single-crystal Silicon Carbide (SiC) substrate [2]. With a band gap energy value of about 3.2 eV at room temperature, the latter material is transparent at 780nm, potentially restoring quasi full optical access to the atoms. Moreover, it combines a very high electrical resistivity with a very high thermal conductivity, making it a good candidate for supporting wires with large currents without the need of any additional electrical insulation layer [3].

A LYSO crystal array readout by silicon photomultipliers as compact detector for space applications

DOE PAGES

Kryemadhi, A.; Barner, L.; Grove, A.; ...

2017-10-31

Precise measurements of GeV range gamma rays help narrow down among var- ious gamma emission models and increase sensitivity for dark matter searches. Construction of precise as well as compact instruments requires detectors with high efficiency, high stopping power, excellent energy resolution, and excellent angular resolution. Fast and bright crystal scintillators coupled with small foot- print photo-detectors are suitable candidates. We prototyped a detector array consisting of four LYSO crystals where each crystal is read out by a 2x2 SensL ArrayJ60035 silicon photomultipliers. The LYSO crystals were chosen because of their good light yield, fast decay time, demonstrated radiation hardness,more » and small radiation length. Here, we used the silicon photomultiplier arrays as photo- detectors because of their small size, simple readout, low voltage operation, and immunity to magnetic elds. We also studied the detector performance in the energy range of interest by exposing it to 2-16 GeV particles produced at the Test Beam Facility of Fermi National Accelerator Laboratory.« less

Progress Toward Attractive Stellarators

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

Neilson, G H; Brown, T G; Gates, D A

The quasi-axisymmetric stellarator (QAS) concept offers a promising path to a more compact stellarator reactor, closer in linear dimensions to tokamak reactors than previous stellarator designs. Concept improvements are needed, however, to make it more maintainable and more compatible with high plant availability. Using the ARIES-CS design as a starting point, compact stellarator designs with improved maintenance characteristics have been developed. While the ARIES-CS features a through-the-port maintenance scheme, we have investigated configuration changes to enable a sector-maintenance approach, as envisioned for example in ARIES AT. Three approaches are reported. The first is to make tradeoffs within the QAS designmore » space, giving greater emphasis to maintainability criteria. The second approach is to improve the optimization tools to more accurately and efficiently target the physics properties of importance. The third is to employ a hybrid coil topology, so that the plasma shaping functions of the main coils are shared more optimally, either with passive conductors made of high-temperature superconductor or with local compensation coils, allowing the main coils to become simpler. Optimization tools are being improved to test these approaches.« less

Accuracy of Binary Black Hole waveforms for Advanced LIGO searches

NASA Astrophysics Data System (ADS)

Kumar, Prayush; Barkett, Kevin; Bhagwat, Swetha; Chu, Tony; Fong, Heather; Brown, Duncan; Pfeiffer, Harald; Scheel, Mark; Szilagyi, Bela

2015-04-01

Coalescing binaries of compact objects are flagship sources for the first direct detection of gravitational waves with LIGO-Virgo observatories. Matched-filtering based detection searches aimed at binaries of black holes will use aligned spin waveforms as filters, and their efficiency hinges on the accuracy of the underlying waveform models. A number of gravitational waveform models are available in literature, e.g. the Effective-One-Body, Phenomenological, and traditional post-Newtonian ones. While Numerical Relativity (NR) simulations provide for the most accurate modeling of gravitational radiation from compact binaries, their computational cost limits their application in large scale searches. In this talk we assess the accuracy of waveform models in two regions of parameter space, which have only been explored cursorily in the past: the high mass-ratio regime as well as the comparable mass-ratio + high spin regime.s Using the SpEC code, six q = 7 simulations with aligned-spins and lasting 60 orbits, and tens of q ∈ [1,3] simulations with high black hole spins were performed. We use them to study the accuracy and intrinsic parameter biases of different waveform families, and assess their viability for Advanced LIGO searches.

Advances in High Energy Solid-State 2-micron Laser Transmitter Development for Ground and Airborne Wind and CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Chen, Songsheng; Kavaya, Michael J.; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Modlin, Edward A.; Koch, Grady;

Lensless digital holographic microscopy and its applications in biomedicine and environmental monitoring.

PubMed

Wu, Yichen; Ozcan, Aydogan

2018-03-01

Optical compound microscope has been a major tool in biomedical imaging for centuries. Its performance relies on relatively complicated, bulky and expensive lenses and alignment mechanics. In contrast, the lensless microscope digitally reconstructs microscopic images of specimens without using any lenses, as a result of which it can be made much smaller, lighter and lower-cost. Furthermore, the limited space-bandwidth product of objective lenses in a conventional microscope can be significantly surpassed by a lensless microscope. Such lensless imaging designs have enabled high-resolution and high-throughput imaging of specimens using compact, portable and cost-effective devices to potentially address various point-of-care, global-health and telemedicine related challenges. In this review, we discuss the operation principles and the methods behind lensless digital holographic on-chip microscopy. We also go over various applications that are enabled by cost-effective and compact implementations of lensless microscopy, including some recent work on air quality monitoring, which utilized machine learning for high-throughput and accurate quantification of particulate matter in air. Finally, we conclude with a brief future outlook of this computational imaging technology. Copyright © 2017 Elsevier Inc. All rights reserved.

Laser Development for Gravitational-Wave Interferometry in Space

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2012-01-01

We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

Design, fabrication, and optimization of quantum cascade laser cavities and spectroscopy of the intersubband gain

NASA Astrophysics Data System (ADS)

Dirisu, Afusat Olayinka

Quantum Cascade (QC) lasers are intersubband light sources operating in the wavelength range of ˜ 3 to 300 mum and are used in applications such as sensing (environmental, biological, and hazardous chemical), infrared countermeasures, and free-space infrared communications. The mid-infrared range (i.e. lambda ˜ 3-30 mum) is of particular importance in sensing because of the strong interaction of laser radiation with various chemical species, while in free space communications the atmospheric windows of 3-5 mum and 8-12 mum are highly desirable for low loss transmission. Some of the requirements of these applications include, (1) high output power for improved sensitivity; (2) high operating temperatures for compact and cost-effective systems; (3) wide tunability; (4) single mode operation for high selectivity. In the past, available mid-infrared sources, such as the lead-salt and solid-state lasers, were bulky, expensive, or emit low output power. In recent years, QC lasers have been explored as cost-effective and compact sources because of their potential to satisfy and exceed all the above requirements. Also, the ultrafast carrier lifetimes of intersubband transitions in QC lasers are promising for high bandwidth free-space infrared communication. This thesis was focused on the improvement of QC lasers through the design and optimization of the laser cavity and characterization of the laser gain medium. The optimization of the laser cavity included, (1) the design and fabrication of high reflection Bragg gratings and subwavelength antireflection gratings, by focused ion beam milling, to achieve tunable, single mode and high power QC lasers, and (2) modeling of slab-coupled optical waveguide QC lasers for high brightness output beams. The characterization of the QC laser gain medium was carried out using the single-pass transmission experiment, a sensitive measurement technique, for probing the intersubband transitions and the electron distribution of QC lasers under different temperatures and applied bias conditions, unlike typical infrared measurement techniques that are restricted to non-functional devices. With the single-pass technique, basic understanding of the physics behind the workings of the QC laser gain can be achieved, which is invaluable in the design of QC lasers with high output power and high operating temperatures.

Scale-Up Method for the Shock Compaction of Powders

NASA Astrophysics Data System (ADS)

Carton, E. P.; Stuivinga, M.

2004-07-01

Shock wave compaction in the cylindrical configuration lends itself to be scaled-up for small-scale industrial applications. While scaling up in the axial direction is easy, scaling up in the lateral direction is less straightforward and may lead to cracks in the center. A different scale up method is presented here; aluminum tubes are filled with the powder to be compacted and placed in a circle inside a large metal tube, with a metal shock wave reflector in the center. The space in between is filled with an inert powder medium: alumina, salt or sand. It is found that salt is the best medium for the integrity of the aluminum tube and for the ease of removal of the aluminum tube out of the (densified) powder medium. Experimental results of (slightly ellipsoidal) shock compacted tubes that are produced this way are shown as an example. In the case of B4C, after infiltration with the aluminum of the tube, fully dense cermet compacts without any cracks are thus produced, batch by batch.

Design and fabrication of metal briquette machine for shop floor

NASA Astrophysics Data System (ADS)

Pramod, R.; Kumar, G. B. Veeresh; Prashanth B., N.

2017-07-01

Efforts have to be taken to ensure efficient waste management system in shop floors, with minimum utilization of space and energy when it comes to disposing metal chips formed during machining processes. The salvaging of junk metallic chips and the us e of scrap are important for the economic production of a steelworks. For this purpose, we have fabricated a metal chip compaction machine, which can compact the metal chips into small briquettes. The project started with the survey of chips formed in shop floors and the practices involved in waste management. Study was done on the requirements for a better compaction. The heating chamber was designed taking into consideration the temperature required for an easy compaction of the metal chips. The power source for compaction and the pneumatic design for mechanism was done following the appropriate calculations regarding the air pressure provided and thrust required. The processes were tested under different conditions and found effective. The fabrication of the machine has been explained in detail and the results have been discussed.

A Piezoelectric Unimorph Deformable Mirror Concept by Wafer Transfer for Ultra Large Space Telescopes

NASA Technical Reports Server (NTRS)

Yang, Eui-Hyeok; Shcheglov, Kirill

2002-01-01

Future concepts of ultra large space telescopes include segmented silicon mirrors and inflatable polymer mirrors. Primary mirrors for these systems cannot meet optical surface figure requirements and are likely to generate over several microns of wavefront errors. In order to correct for these large wavefront errors, high stroke optical quality deformable mirrors are required. JPL has recently developed a new technology for transferring an entire wafer-level mirror membrane from one substrate to another. A thin membrane, 100 mm in diameter, has been successfully transferred without using adhesives or polymers. The measured peak-to-valley surface error of a transferred and patterned membrane (1 mm x 1 mm x 0.016 mm) is only 9 nm. The mirror element actuation principle is based on a piezoelectric unimorph. A voltage applied to the piezoelectric layer induces stress in the longitudinal direction causing the film to deform and pull on the mirror connected to it. The advantage of this approach is that the small longitudinal strains obtainable from a piezoelectric material at modest voltages are thus translated into large vertical displacements. Modeling is performed for a unimorph membrane consisting of clamped rectangular membrane with a PZT layer with variable dimensions. The membrane transfer technology is combined with the piezoelectric bimorph actuator concept to constitute a compact deformable mirror device with a large stroke actuation of a continuous mirror membrane, resulting in a compact A0 systems for use in ultra large space telescopes.

Adaptive multiconfigurational wave functions.

PubMed

Evangelista, Francesco A

2014-03-28

A method is suggested to build simple multiconfigurational wave functions specified uniquely by an energy cutoff Λ. These are constructed from a model space containing determinants with energy relative to that of the most stable determinant no greater than Λ. The resulting Λ-CI wave function is adaptive, being able to represent both single-reference and multireference electronic states. We also consider a more compact wave function parameterization (Λ+SD-CI), which is based on a small Λ-CI reference and adds a selection of all the singly and doubly excited determinants generated from it. We report two heuristic algorithms to build Λ-CI wave functions. The first is based on an approximate prescreening of the full configuration interaction space, while the second performs a breadth-first search coupled with pruning. The Λ-CI and Λ+SD-CI approaches are used to compute the dissociation curve of N2 and the potential energy curves for the first three singlet states of C2. Special attention is paid to the issue of energy discontinuities caused by changes in the size of the Λ-CI wave function along the potential energy curve. This problem is shown to be solvable by smoothing the matrix elements of the Hamiltonian. Our last example, involving the Cu2O2(2+) core, illustrates an alternative use of the Λ-CI method: as a tool to both estimate the multireference character of a wave function and to create a compact model space to be used in subsequent high-level multireference coupled cluster computations.

The isentropic quantum drift-diffusion model in two or three space dimensions

NASA Astrophysics Data System (ADS)

Chen, Xiuqing

2009-05-01

We investigate the isentropic quantum drift-diffusion model, a fourth order parabolic system, in space dimensions d = 2, 3. First, we establish the global weak solutions with large initial value and periodic boundary conditions. Then we show the semiclassical limit by delicate interpolation estimates and compactness argument.

The Most Compact Bright Radio-loud AGNs. II. VLBA Observations of 10 Sources at 43 and 86 GHz

NASA Astrophysics Data System (ADS)

Cheng, X.-P.; An, T.; Hong, X.-Y.; Yang, J.; Mohan, P.; Kellermann, K. I.; Lister, M. L.; Frey, S.; Zhao, W.; Zhang, Z.-L.; Wu, X.-C.; Li, X.-F.; Zhang, Y.-K.

2018-01-01

Radio-loud active galactic nuclei (AGNs), hosting powerful relativistic jet outflows, provide an excellent laboratory for studying jet physics. Very long baseline interferometry (VLBI) enables high-resolution imaging on milli-arcsecond (mas) and sub-mas scales, making it a powerful tool to explore the inner jet structure, shedding light on the formation, acceleration, and collimation of AGN jets. In this paper, we present Very Long Baseline Array observations of 10 radio-loud AGNs at 43 and 86 GHz that were selected from the Planck catalog of compact sources and are among the brightest in published VLBI images at and below 15 GHz. The image noise levels in our observations are typically 0.3 and 1.5 mJy beam‑1 at 43 and 86 GHz, respectively. Compared with the VLBI data observed at lower frequencies from the literature, our observations with higher resolutions (with the highest resolution being up to 0.07 mas at 86 GHz and 0.18 mas at 43 GHz) and at higher frequencies detected new jet components at sub-parsec scales, offering valuable data for studies of the physical properties of the innermost jets. These include the compactness factor of the radio structure (the ratio of core flux density to total flux density), and core brightness temperature ({T}{{b}}). In all these sources, the compact core accounts for a significant fraction (> 60 % ) of the total flux density. Their correlated flux density at the longest baselines is higher than 0.16 Jy. The compactness of these sources make them good phase calibrators of millimeter-wavelength ground-based and space VLBI.

Sub-mm galaxies as progenitors of compact quiescent galaxies

NASA Astrophysics Data System (ADS)

Toft, Sune

2015-08-01

Three billion years after the big bang (at redshift z=2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3 < z < 6). Simulations show that gas-rich major mergers can give rise to such starbursts which produce dense remnants. Sub-millimetre selected galaxies (SMGs) are prime examples of intense, gas-rich, starbursts. With a new, mass-complete spectroscopic sample of compact quiescent galaxies at z=2 and a statistically well-understood sample of SMGs, we show that z = 3 -6 SMGs are consistent with being the progenitors of z = 2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42 (+40/-29) Myr (consistent with independent estimates), indicating that the bulk of stars in these massive galaxies were formed in a major, early surge of star-formation. These results suggests a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star-formation through their appearance as high stellardensity galaxy cores and to their ultimate fate as giant ellipticals.If time permits i will show novel, spatially resolved spectroscopic observations of the inner regions (r2, allowing for strong new constraints on their formation and evolutionary path

A comprehensive HST BVI catalogue of star clusters in five Hickson compact groups of galaxies

NASA Astrophysics Data System (ADS)

Fedotov, K.; Gallagher, S. C.; Durrell, P. R.; Bastian, N.; Konstantopoulos, I. S.; Charlton, J.; Johnson, K. E.; Chandar, R.

2015-05-01

We present a photometric catalogue of star cluster candidates in Hickson compact groups (HCGs) 7, 31, 42, 59, and 92, based on observations with the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope. The catalogue contains precise cluster positions (right ascension and declination), magnitudes, and colours in the BVI filters. The number of detected sources ranges from 2200 to 5600 per group, from which we construct the high-confidence sample by applying a number of criteria designed to reduce foreground and background contaminants. Furthermore, the high-confidence cluster candidates for each of the 16 galaxies in our sample are split into two subpopulations: one that may contain young star clusters and one that is dominated by globular older clusters. The ratio of young star cluster to globular cluster candidates varies from group to group, from equal numbers to the extreme of HCG 31 which has a ratio of 8 to 1, due to a recent starburst induced by interactions in the group. We find that the number of blue clusters with MV < -9 correlates well with the current star formation rate in an individual galaxy, while the number of globular cluster candidates with MV < -7.8 correlates well (though with large scatter) with the stellar mass. Analyses of the high-confidence sample presented in this paper show that star clusters can be successfully used to infer the gross star formation history of the host groups and therefore determine their placement in a proposed evolutionary sequence for compact galaxy groups.

Sequence-stratigraphic controls on sandstone diagenesis: An example from the Williams Fork formation, Piceance Basin, Colorado

NASA Astrophysics Data System (ADS)

Aboktef, Adel

This study documents the distribution of diagenetic alterations in Williams Fork fluvial sandstones, assess sequence stratigraphic controls on diagenetic features, and addresses diagenetic impacts on porosity. Petrographic point counts of 220 thin sections from six wells forms the database. The near absence of potassium feldspar and volcanic rock fragments in the lower Williams Fork interval and increasing plagioclase content upward represent changes in sediment provenance rather than stratigraphic variability in diagenesis. The lower Williams Fork sands are from sedimentary sources whereas middle and upper Williams Fork sands include input from magmatic arcs and basement uplifts. Compaction, early and late cementation, dissolution, and replacement by calcite or clay minerals combined to alter Williams Fork sandstones. Infiltration of clays occurred prior to any burial. Chlorite, quartz, non-ferroan calcite, compaction and dissolution features, and kaolinite formed during eo-diagenesis at <70°C. More quartz, compaction and dissolution features, plus albite, illite, mixed-layer illite/smectite, ferroan calcite, and dolomite formed in the meso-diagenetic realm (>70°C). Four of these features show spatial variability with respect to systems tracts. Infiltrated clays are concentrated in lowstand systems tracts (LST) and highstand systems tracts (HST) because accommodation space rose slow or fell during deposition of those sands, which led to prolonged sand body exposure on floodplain and ample opportunities for downward percolation of mud during flood events. Concentration of pseudomatrix (mud intraclasts) in HST and LST deposits resulted from floodplain erosion when base-level fell with decreasing accommodation space. Authigenic chlorite formed in the HST and transgressive systems tracts (TST) of the upper half of the Williams Fork Formation because volcanic clasts are abundant in that interval. Quartz overgrowths are more likely to exceed 7% in TST deposits for reasons that are unknown. High total clay content (infiltrated, grain coatings, pseudomatrix) does inhibit quartz overgrowths in all systems tracts. Williams Fork sandstones form low-permeability tight-gas reservoirs. Primary porosity was almost entirely destroyed by compaction and cementation. Reservoir rock resulted from one of two pathways. Eogenetic authigenic chlorite and/or calcite inhibited quartz cementation, minimized compaction and protected some primary porosity. Alternately, dissolution of framework grains or cements created secondary porosity. The later pathway tends to be the more dominant.

Lead telluride as a thermoelectric material for thermoelectric power generation

NASA Astrophysics Data System (ADS)

Dughaish, Z. H.

2002-09-01

The specialized applications of thermoelectric generators are very successful and have motivated a search for materials with an improved figure of merit Z, and also for materials which operate at elevated temperatures. Lead telluride, PbTe, is an intermediate thermoelectric power generator. Its maximum operating temperature is 900 K. PbTe has a high melting point, good chemical stability, low vapor pressure and good chemical strength in addition to high figure of merit Z. Recently, research in thermoelectricity aims to obtain new improved materials for autonomous sources of electrical power in specialized medical, terrestial and space applications and to obtain an unconventional energy source after the oil crises of 1974. Although the efficiency of thermoelectric generators is rather low, typically ∼5%, the other advantages, such as compactness, silent, reliability, long life, and long period of operation without attention, led to a wide range of applications. PbTe thermoelectric generators have been widely used by the US army, in space crafts to provide onboard power, and in pacemakers batteries. The general physical properties of lead telluride and factors affecting the figure of merit have been reviewed. Various possibilities of improving the figure of merit of the material have been given, including effect of grain size on reducing the lattice thermal conductivity λL. Comparison of some transport properties of lead telluride with other thermoelectric materials and procedures of preparing compacts with transport properties very close to the single crystal values from PbTe powder by cold and hot-pressing techniques are discussed.

An Active Black Hole in a Compact Dwarf

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-05-01

A new type of galaxy has just been added to the galaxy zoo: a small, compact, and old elliptical galaxy that shows signs of a monster black hole actively accreting material in its center. What can this unusual discovery tell us about how compact elliptical galaxies form?A New Galactic BeastCompact elliptical galaxies are an extremely rare early-type dwarf galaxy. Consistent with their name, compact ellipticals are small, very compact collections of ancient stars; these galaxies exhibit a high surface brightness and arent actively forming stars.Optical view of the ancient compact elliptical galaxy SDSS J085431.18+173730.5 (center of image) in an SDSS color composite image. [Adapted from Paudel et al. 2016]Most compact ellipticals are found in dense environments, particularly around massive galaxies. This has led astronomers to believe that compact ellipticals might form via the tidal stripping of a once-large galaxy in interactions with another, massive galaxy. In this model, once the original galaxys outer layers are stripped away, the compact inner bulge component would be left behind as a compact elliptical galaxy. Recent discoveries of a few isolated compact ellipticals, however, have strained this model.Now a new galaxy has been found to confuse our classification schemes: the first-ever compact elliptical to also display signs of an active galactic nucleus. Led by Sanjaya Paudel (Korea Astronomy and Space Science Institute), a team of scientists discovered SDSS J085431.18+173730.5 serendipitously in Sloan Digital Sky Survey data. The team used SDSS images and spectroscopy in combination with data from the Canada-France-Hawaii Telescope to learn more about this unique galaxy.Puzzling CharacteristicsSDSS J085431.18+173730.5 presents an interesting conundrum. Ancient compact ellipticals are supposed to be devoid of gas, with no fuel left to trigger nuclear activity. Yet SDSS J085431.18+173730.5 clearly shows the emission lines that indicate active accretion onto a supermassive black hole of ~2 million solar masses, according to the authors estimates. Paudel and collaboratorsshow that this mass is consistent with the low-mass extension of the known scaling relation between central black-hole mass and brightness of the host galaxy.Central black hole mass vs. bulge K-band magnitude. SDSS J085431.18+173730.5 (red dot) falls right on the low-mass extension of the observed scaling relation. It has similar properties to M32, another compact elliptical galaxy. [Adapted from Paudel et al. 2016]To add to the mystery, SDSS J085431.18+173730.5 has no nearby neighbors: like the few other isolated compact ellipticals recently discovered, there are no massive galaxies in the immediate vicinity that could have led to its tidal stripping. So how was this puzzling ancient galaxy formed?The authors of this study support a previously proposed flyby scenario: isolated compact ellipticals may simply be tidally stripped systems that ran away from their hosts. Paudel and collaborators suggest that SDSS J085431.18+173730.5 might have long ago interacted with NGC 2672 a galaxy group located a whopping 6.5 million light-years away before being flung out to its current location.Further studies of this unique galaxys emission profile, as well as efforts to learn about its underlying stellar population and central kinematics, will hopefully help us to better understand not only the origins of this galaxy, but how all compact ellipticals form and evolve.CitationSanjaya Paudel et al 2016 ApJ 820 L19. doi:10.3847/2041-8205/820/1/L19

Soil compaction vulnerability at Organ Pipe Cactus National Monument, Arizona

USGS Publications Warehouse

Webb, Robert H.; Nussear, Kenneth E.; Carmichael, Shinji; Esque, Todd C.

2014-01-01

Compaction vulnerability of different types of soils by hikers and vehicles is poorly known, particularly for soils of arid and semiarid regions. Engineering analyses have long shown that poorly sorted soils (for example, sandy loams) compact to high densities, whereas well-sorted soils (for example, eolian sand) do not compact, and high gravel content may reduce compaction. Organ Pipe Cactus National Monument (ORPI) in southwestern Arizona, is affected greatly by illicit activities associated with the United States–Mexico border, and has many soils that resource managers consider to be highly vulnerable to compaction. Using geospatial soils data for ORPI, compaction vulnerability was estimated qualitatively based on the amount of gravel and the degree of sorting of sand and finer particles. To test this qualitative assessment, soil samples were collected from 48 sites across all soil map units, and undisturbed bulk densities were measured. A scoring system was used to create a vulnerability index for soils on the basis of particle-size sorting, soil properties derived from Proctor compaction analyses, and the field undisturbed bulk densities. The results of the laboratory analyses indicated that the qualitative assessments of soil compaction vulnerability underestimated the area of high vulnerability soils by 73 percent. The results showed that compaction vulnerability of desert soils, such as those at ORPI, can be quantified using laboratory tests and evaluated using geographic information system analyses, providing a management tool that managers potentially could use to inform decisions about activities that reduce this type of soil disruption in protected areas.

Meso-Scale Experimental & Numerical Studies for Predicting Macro-scale Performance of Advanced Reactive Materials (ARMs)

DTIC Science & Technology

2015-04-01

of impact-initiated reactions in Ti-Al-B based reactive materials in the form of compacts of powders of different sizes and morphologies . The major...More specifically, the influence of material-inherent elastic/plastic properties and reactant configuration (e.g., porosity, morphology , spacing...materials in the form of compacts of powders of different sizes and morphologies . The major goal is to delineate how processes of localized deformation and

Compact Color Schlieren Optical System

NASA Technical Reports Server (NTRS)

Buchele, Donald R.; Griffin, Devon W.

1996-01-01

Compact, rugged optical system developed for use in rainbow schlieren deflectometry. Features unobscured telescope with focal-length/aperture-width ratio of 30. Made of carefully selected but relatively inexpensive parts. All of lenses stock items. By-product of design is optical system with loose tolerances on interlens spacing. One of resulting advantages, insensitivity to errors in fabrication of optomechanical mounts. Another advantage is ability to compensate for some of unit-to-unit variations inherent in stock lenses.

Development of a US Gravitational Wave Laser System for LISA

NASA Technical Reports Server (NTRS)

Camp, Jordan B.; Numata, Kenji

2015-01-01

A highly stable and robust laser system is a key component of the space-based LISA mission architecture.In this talk I will describe our plans to demonstrate a TRL 5 LISA laser system at Goddard Space Flight Center by 2016.The laser system includes a low-noise oscillator followed by a power amplifier. The oscillator is a low-mass, compact 10mW External Cavity Laser, consisting of a semiconductor laser coupled to an optical cavity, built by the laser vendorRedfern Integrated Optics. The amplifier is a diode-pumped Yb fiber with 2W output, built at Goddard. I will show noiseand reliability data for the full laser system, and describe our plans to reach TRL 5 by 2016.

Cryocoolers for Space

NASA Technical Reports Server (NTRS)

Kittel, Peter; Feller, Jeff; Roach, Pat; Kashani, Ali; Helvensteijn, Ben

2004-01-01

Many planetary and Earth science missions require cooling to increase sensitivity and reduce thermal noise of detectors, for preserving high Isp propellants, or for protecting instruments from hostile environments. For space applications, such cooling requires reliable, efficient, long-life coolers that are relatively compact, lightweight, and have low vibration. We have developed and are developing coolers that meet these requirements over a wide range of temperatures. These include pulse tube coolers cooling from 300 K to below 6 K, a magnetic cooler cooling from 10 K to 2 K, a 3He sorption cooler cooling from 2 K to 0.3 K and a helium dilution cooler cooling from 0.3 K to 0.05 K. Details of these coolers and their advantages are presented.

NASA Tech Briefs, March 2010

NASA Technical Reports Server (NTRS)

2010-01-01

Topics covered include: Software Tool Integrating Data Flow Diagrams and Petri Nets; Adaptive Nulling for Interferometric Detection of Planets; Reducing the Volume of NASA Earth-Science Data; Reception of Multiple Telemetry Signals via One Dish Antenna; Space-Qualified Traveling-Wave Tube; Smart Power Supply for Battery-Powered Systems; Parallel Processing of Broad-Band PPM Signals; Inexpensive Implementation of Many Strain Gauges; Constant-Differential-Pressure Two-Fluid Accumulator; Inflatable Tubular Structures Rigidized with Foams; Power Generator with Thermo-Differential Modules; Mechanical Extraction of Power From Ocean Currents and Tides; Nitrous Oxide/Paraffin Hybrid Rocket Engines; Optimized Li-Ion Electrolytes Containing Fluorinated Ester Co-Solvents; Probabilistic Multi-Factor Interaction Model for Complex Material Behavior; Foldable Instrumented Bits for Ultrasonic/Sonic Penetrators; Compact Rare Earth Emitter Hollow Cathode; High-Precision Shape Control of In-Space Deployable Large Membrane/Thin-Shell Reflectors; Rapid Active Sampling Package; Miniature Lightweight Ion Pump; Cryogenic Transport of High-Pressure-System Recharge Gas; Water-Vapor Raman Lidar System Reaches Higher Altitude; Compact Ku-Band T/R Module for High-Resolution Radar Imaging of Cold Land Processes; Wide-Field-of-View, High-Resolution, Stereoscopic Imager; Electrical Capacitance Volume Tomography with High-Contrast Dielectrics; Wavefront Control and Image Restoration with Less Computing; Polarization Imaging Apparatus; Stereoscopic Machine-Vision System Using Projected Circles; Metal Vapor Arcing Risk Assessment Tool; Performance Bounds on Two Concatenated, Interleaved Codes; Parameterizing Coefficients of a POD-Based Dynamical System; Confidence-Based Feature Acquisition; Algorithm for Lossless Compression of Calibrated Hyperspectral Imagery; Universal Decoder for PPM of any Order; Algorithm for Stabilizing a POD-Based Dynamical System; Mission Reliability Estimation for Repairable Robot Teams; Processing AIRS Scientific Data Through Level 3; Web-Based Requesting and Scheduling Use of Facilities; AutoGen Version 5.0; Time-Tag Generation Script; PPM Receiver Implemented in Software; Tropospheric Emission Spectrometer Product File Readers; Reporting Differences Between Spacecraft Sequence Files; Coordinating "Execute" Data for ISS and Space Shuttle; Database for Safety-Oriented Tracking of Chemicals; Apparatus for Cold, Pressurized Biogeochemical Experiments; Growing B Lymphocytes in a Three-Dimensional Culture System; Tissue-like 3D Assemblies of Human Broncho-Epithelial Cells; Isolation of Resistance-Bearing Microorganisms; Oscillating Cell Culture Bioreactor; and Liquid Cooling/Warming Garment.

Vascular Spaces in Compact Bone: A Technique to Correct a Common Misinterpretation of Structure

ERIC Educational Resources Information Center

Locke, M.; Dean, Rob L.

2003-01-01

Old bones are often discolored by the grime that infiltrates spaces in the matrix once occupied by blood vessels. This suggested that allowing dry bone to absorb colorants might be a useful way to show the three dimensional complexity of bone vascularization. The authors have developed a simple way to show blood vessels spaces in bone at a glance…

Submillimeter Galaxies as Progenitors of Compact Quiescent Galaxies

NASA Technical Reports Server (NTRS)

Toft, S.; Smolcic, V.; Magnelli, B.; Karim, A.; Zirm, A.; Michalowski, M.; Capak, P.; Sheth, K.; Schawinski, K.; Krogager, J.-K.;

Submillimeter Galaxies as Progenitors of Compact Quiescent Galaxies

NASA Astrophysics Data System (ADS)

Toft, S.; Smolčić, V.; Magnelli, B.; Karim, A.; Zirm, A.; Michalowski, M.; Capak, P.; Sheth, K.; Schawinski, K.; Krogager, J.-K.; Wuyts, S.; Sanders, D.; Man, A. W. S.; Lutz, D.; Staguhn, J.; Berta, S.; Mccracken, H.; Krpan, J.; Riechers, D.

2014-02-01

Three billion years after the big bang (at redshift z = 2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low-redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3 < z < 6). Simulations show that gas-rich major mergers can give rise to such starbursts, which produce dense remnants. Submillimeter-selected galaxies (SMGs) are prime examples of intense, gas-rich starbursts. With a new, representative spectroscopic sample of compact, quiescent galaxies at z = 2 and a statistically well-understood sample of SMGs, we show that z = 3-6 SMGs are consistent with being the progenitors of z = 2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses, and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42^{+40}_{-29} Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star formation. These results suggest a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star formation through their appearance as high stellar-density galaxy cores and to their ultimate fate as giant ellipticals.

Discretizing singular point sources in hyperbolic wave propagation problems

DOE PAGES

Petersson, N. Anders; O'Reilly, Ossian; Sjogreen, Bjorn; ...

2016-06-01

Here, we develop high order accurate source discretizations for hyperbolic wave propagation problems in first order formulation that are discretized by finite difference schemes. By studying the Fourier series expansions of the source discretization and the finite difference operator, we derive sufficient conditions for achieving design accuracy in the numerical solution. Only half of the conditions in Fourier space can be satisfied through moment conditions on the source discretization, and we develop smoothness conditions for satisfying the remaining accuracy conditions. The resulting source discretization has compact support in physical space, and is spread over as many grid points as themore » number of moment and smoothness conditions. In numerical experiments we demonstrate high order of accuracy in the numerical solution of the 1-D advection equation (both in the interior and near a boundary), the 3-D elastic wave equation, and the 3-D linearized Euler equations.« less

Rapid subsidence over oil fields measured by SAR

NASA Technical Reports Server (NTRS)

Fielding, E. J.; Blom, R. G.; Goldstein, R. M.

1998-01-01

The Lost Hills and Belridge oil felds are in the San Joaquin Valley, California. The major oil reservoir is high porosity and low permeability diatomite. Extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction, forming a surface subsidence bowl. We measure this subsidence from space using interferometric analysis of SAR (Synthetic Aperture Radar) data collected by the European Space Agency Remote Sensing Satellites (ERS-1 and ERS-2). Maximum subsidence rates are as high as 40 mm in 35 days or > 400 mm/yr, measured from interferograms with time separations ranging from one day to 26 months. The 8- and 26-month interferograms contain areas where the subsidence gradient exceeds the measurement possible with ERS SAR, but shows increased detail in areas of less rapid subsidence. Synoptic mapping of subsidence distribution from satellite data powerfully complements ground-based techniques, permits measurements where access is difficult, and aids identification of underlying causes.

Numerical solution of the wave equation with variable wave speed on nonconforming domains by high-order difference potentials

NASA Astrophysics Data System (ADS)

Britt, S.; Tsynkov, S.; Turkel, E.

2018-02-01

We solve the wave equation with variable wave speed on nonconforming domains with fourth order accuracy in both space and time. This is accomplished using an implicit finite difference (FD) scheme for the wave equation and solving an elliptic (modified Helmholtz) equation at each time step with fourth order spatial accuracy by the method of difference potentials (MDP). High-order MDP utilizes compact FD schemes on regular structured grids to efficiently solve problems on nonconforming domains while maintaining the design convergence rate of the underlying FD scheme. Asymptotically, the computational complexity of high-order MDP scales the same as that for FD.

Physical and mechanical properties of self-compacting concrete containing superplasticizer and metakaolin

NASA Astrophysics Data System (ADS)

Shahidan, Shahiron; Tayeh, Bassam A.; Jamaludin, A. A.; Bahari, N. A. A. S.; Mohd, S. S.; Zuki Ali, N.; Khalid, F. S.

2017-11-01

The development of concrete technology shows a variety of admixtures in concrete to produce special concrete. This includes the production of self-compacting concrete which is able to fill up all spaces, take formwork shapes and pass through congested reinforcement bars without vibrating or needing any external energy. In this study, the main objective is to compare the physical and mechanical properties of self-compacting concrete containing metakaolin with normal concrete. Four types of samples were produced to study the effect of metakaolin towards the physical and mechanical properties of self-compacting concrete where 0%, 5%, 10% and 15% of metakaolin were used as cement replacement. The physical properties were investigated using slump test for normal concrete and slump flow test for self-compacting concrete. The mechanical properties were tested for compressive strength and tensile strength. The findings of this study show that the inclusion of metakaolin as cement replacement can increase both compressive and tensile strength compared to normal concrete. The highest compressive strength was found in self-compacting concrete with 15% metakaolin replacement at 53.3 MPa while self-compacting concrete with 10% metakaolin replacement showed the highest tensile strength at 3.6 MPa. On top of that, the finishing or concrete surface of both cube and cylinder samples made of self-compacting concrete produced a smooth surface with the appearance of less honeycombs compared to normal concrete.

Quantitative evaluation of compactness of concrete-filled fiber-reinforced polymer tubes using piezoceramic transducers and time difference of arrival

NASA Astrophysics Data System (ADS)

Xu, Yang; Luo, Mingzhang; Hei, Chuang; Song, Gangbing

2018-03-01

Owing to its light weight and corrosion resistance, the concrete-filled fiber-reinforced polymer tube (CFFT) structure has a broad application prospect; the concrete compactness is key to the strength of CFFTs. To meet the urgent requirement of compactness monitoring of CFFTs, a quantitative method, which uses an array of four equally spaced piezoceramic patches and an ultrasonic time difference of arrival (TDOA) algorithm, is developed. Since the velocity of the ultrasonic wave propagation in fiber-reinforced polymer (FRP) material is about half of that in concrete material, the compactness condition of CFFT impacts the piezoceramic-induced wave propagation in the CFFT, and differentiates the TDOA for different receivers. An important condition is the half compactness, which can be judged by the Half Compactness Indicator (HCI) based on the TDOAs. To characterize the difference of stress wave propagation durations from the emitter to different receivers, which can be utilized to calculate the concrete infill compactness, the TDOA ratio (TDOAR) is introduced. An innovative algorithm is developed in this paper to estimate the compactness of the CFFT using HCI and TDOAR values. Analytical, numerical, and experimental studies based on a CFFT with seven different states of compactness (empty, 1/10, 1/3, 1/2, 2/3, 9/10, and full) are carried out in this research. Analyses demonstrate that there is a good agreement among the analytical, numerical, and experimental results of the proposed method, which employs a piezoceramic transducer array and the TDOAR for quantitative estimating the compactness of concrete infill in a CFFT.

On a product-type operator from weighted Bergman-Orlicz space to some weighted type spaces.

PubMed

Jiang, Zhi-Jie

2015-04-01

Let [Formula: see text] be the open unit disk, [Formula: see text] an analytic self-map of [Formula: see text] and [Formula: see text] an analytic function on [Formula: see text]. Let D be the differentiation operator and [Formula: see text] the weighted composition operator. The boundedness and compactness of the product-type operator [Formula: see text] from the weighted Bergman-Orlicz space to the Bers type space, weighted Bloch space and weighted Zygmund space on [Formula: see text] are characterized.

About the atomic structures of icosahedral quasicrystals

NASA Astrophysics Data System (ADS)

Quiquandon, Marianne; Gratias, Denis

2014-01-01

This paper is a survey of the crystallographic methods that have been developed these last twenty five years to decipher the atomic structures of the icosahedral stable quasicrystals since their discovery in 1982 by D. Shechtman. After a brief recall of the notion of quasiperiodicity and the natural description of Z-modules in 3-dim as projection of regular lattices in N>3-dim spaces, we give the basic geometrical ingredients useful to describe icosahedral quasicrystals as irrational 3-dim cuts of ordinary crystals in 6-dim space. Atoms are described by atomic surfaces (ASs) that are bounded volumes in the internal (or perpendicular) 3-dim space and the intersections of which with the physical space are the actual atomic positions. The main part of the paper is devoted to finding the major properties of quasicrystalline icosahedral structures. As experimentally demonstrated, they can be described with a surprisingly few high symmetry ASs located at high symmetry special points in 6-dim space. The atomic structures are best described by aggregations and intersections of high symmetry compact interpenetrating atomic clusters. We show here that the experimentally relevant clusters are derived from one generic cluster made of two concentric triacontahedra scaled by τ and an external icosidodecahedron. Depending on which ones of the orbits of this cluster are eventually occupied by atoms, the actual atomic clusters are of type Bergman, Mackay, Tsai and others….

Dose measurements in space by the Hungarian Pille TLD system.

PubMed

Apathy, I; Deme, S; Feher, I; Akatov, Y A; Reitz, G; Arkhanguelski, V V

2002-10-01

Exposure of crew, equipment, and experiments to the ambient space radiation environment in low Earth orbit poses one of the most significant problems to long-term space habitation. Accurate dose measurement has become increasingly important during the assembly (extravehicular activity (EVA)) and operation of space stations such as on Space Station Mir. Passive integrating detector systems such as thermoluminescent dosemeters (TLDs) are commonly used for dosimetry mapping and personal dosimetry on space vehicles. The well-known advantages of passive detector systems are their independence of power supply, small dimensions, high sensitivity, good stability, wide measuring range, resistance to environmental effects, and relatively low cost. Nevertheless, they have the general disadvantage that for evaluation purposes they need a laboratory or large--in mass and power consumption--terrestrial equipment, and consequently they cannot provide time-resolved dose data during long-term space flights. KFKI Atomic Energy Research Institute (KFKI AEKI) has developed and manufactured a series of thermoluminescent dosemeter systems for measuring cosmic radiation doses in the 10 microGy to 10 Gy range, consisting of a set of bulb dosemeters and a compact, self-contained, TLD reader suitable for on-board evaluation of the dosemeters. By means of such a system, highly accurate measurements were carried out on board the Salyut-6, -7 and Mir Space Stations as well as on the Space Shuttle. A detailed description of the system is given and the comprehensive results of these measurements are summarised. c2002 Elsevier Science Ltd. All rights reserved.

Local existence of solutions to the Euler-Poisson system, including densities without compact support

NASA Astrophysics Data System (ADS)

Brauer, Uwe; Karp, Lavi

2018-01-01

Local existence and well posedness for a class of solutions for the Euler Poisson system is shown. These solutions have a density ρ which either falls off at infinity or has compact support. The solutions have finite mass, finite energy functional and include the static spherical solutions for γ = 6/5. The result is achieved by using weighted Sobolev spaces of fractional order and a new non-linear estimate which allows to estimate the physical density by the regularised non-linear matter variable. Gamblin also has studied this setting but using very different functional spaces. However we believe that the functional setting we use is more appropriate to describe a physical isolated body and more suitable to study the Newtonian limit.

SU(1 , 1) and SU(2) approaches to the radial oscillator: Generalized coherent states and squeezing of variances

NASA Astrophysics Data System (ADS)

Rosas-Ortiz, Oscar; Cruz y Cruz, Sara; Enríquez, Marco

2016-10-01

It is shown that each one of the Lie algebras su(1 , 1) and su(2) determine the spectrum of the radial oscillator. States that share the same orbital angular momentum are used to construct the representation spaces of the non-compact Lie group SU(1 , 1) . In addition, three different forms of obtaining the representation spaces of the compact Lie group SU(2) are introduced, they are based on the accidental degeneracies associated with the spherical symmetry of the system as well as on the selection rules that govern the transitions between different energy levels. In all cases the corresponding generalized coherent states are constructed and the conditions to squeeze the involved quadratures are analyzed.

Topological properties of a curved spacetime

NASA Astrophysics Data System (ADS)

Agrawal, Gunjan; Shrivastava, Sampada; Godani, Nisha; Sinha, Soami Pyari

2017-12-01

The present paper aims at the study of a topology on Lorentzian manifolds, defined by Göbel [4] using the ideas of Zeeman [16]. Observing that on the Minkowski space it is the same as Zeeman's time topology, it has been found that a Lorentzian manifold with this topology is path connected, nonfirst countable and nonsimply connected while the Minkowski space with time topology is, in addition nonregular and separable. Furthermore, using the notion of Zeno sequences it is obtained that a compact set does not contain a nonempty open set and that a set is compact if and only if each of its infinite subsets has a limit point if and only if each of its sequences has a convergent subsequence.

Design and Development of NEA Scout Solar Sail Deployer Mechanism

NASA Technical Reports Server (NTRS)

Sobey, Alexander R.; Lockett, Tiffany Russell

2016-01-01

The 6U (approximately10cm x 20cm x 30cm) cubesat Near Earth Asteroid (NEA) Scout, projected for launch in September 2018 aboard the maiden voyage of the Space Launch System (SLS), will utilize a solar sail as its main method of propulsion throughout its approximately 3 year mission to a near earth asteroid. Due to the extreme volume constraints levied onto the mission, an acutely compact solar sail deployment mechanism has been designed to meet the volume and mass constraints, as well as provide enough propulsive solar sail area and quality in order to achieve mission success. The design of such a compact system required the development of approximately half a dozen prototypes in order to identify unforeseen problems and advance solutions. Though finite element analysis was performed during this process in an attempt to quantify forces present within the mechanism during deployment, both the boom and the sail materials do not lend themselves to achieving high-confidence results. This paper focuses on the obstacles of developing a solar sail deployment mechanism for such an application and the lessons learned from a thorough development process. The lessons presented here will have significant applications beyond the NEA Scout mission, such as the development of other deployable boom mechanisms and uses for gossamer-thin films in space.

Diffusion of Eu(III) in compacted bentonite-effect of pH, solution concentration and humic acid.

PubMed

Wang, Xiangke; Chen, Yixue; Wu, Yican

2004-06-01

The effect of pH, Eu(III) solution concentration and humic acid on the diffusion of Eu(III) in compacted bentonite (rho(b) = 1000 +/- 30 kg/m(3)) was studied with "in-diffusion" method at an ionic strength of 0.1M NaClO(4). The results (K(d) values from the first slice and theoretical calculation, apparent and effective diffusion coefficients) derived from the new capillary method are in good agreement with the literature data under similar conditions, and fit the Fick's second law very well. The results suggest that the diffusion of Eu(III) is dependent on pH values and independent on solution concentration in our experimental conditions. Humic acid forms precipitation/complexation with Eu(III) at the surface of compacted bentonite and thus deduces the diffusion/transport of Eu(III) in compacted bentonite. The K(d) values in compacted bentonite are in most cases lower than those in powdered bentonite obtained from batch experiments. The difference between the K(d) values from powdered and compacted bentonite is a strong function of the bulk density of the bentonite. The results suggest that the content of interlaminary space plays a very important role to the diffusion, sorption and migration of Eu(III) in compacted bentonite.

Potential civil mission applications for space nuclear power systems

NASA Technical Reports Server (NTRS)

Ambrus, J. H.; Beatty, R. G. G.

1985-01-01

It is pointed out that the energy needs of spacecraft over the last 25 years have been met by photovoltaic arrays with batteries, primary fuel cells, and radioisotope thermoelectric generators (RTG). However, it might be difficult to satisfy energy requirements for the next generation of space missions with the currently used energy sources. Applications studies have emphasized the need for a lighter, cheaper, and more compact high-energy source than the scaling up of current technologies would permit. These requirements could be satisfied by a nuclear reactor power system. The joint NASA/DOD/DOE SP-100 program is to explore and evaluate this option. Critical elements of the technology are also to be developed, taking into account space reactor systems of the 100 kW class. The present paper is concerned with some of the civil mission categories and concepts which are enabled or significantly enhanced by the performance characteristics of a nuclear reactor energy system.

Compact electro-optical module with polymer waveguides on a flexible substrate for high-density board-level communication

NASA Astrophysics Data System (ADS)

Weiss, J. R. M.; Lamprecht, T.; Meier, N.; Dangel, R.; Horst, F.; Jubin, D.; Beyeler, R.; Offrein, B. J.

2010-02-01

We report on the co-packaging of electrical CMOS transceiver and VCSEL chip arrays on a flexible electrical substrate with optical polymer waveguides. The electro-optical components are attached to the substrate edge and butt-coupled to the waveguides. Electrically conductive silver-ink connects them to the substrate at an angle of 90°. The final assembly contacts the surface of a package laminate with an integrated compressible connector. The module can be folded to save space, requires only a small footprint on the package laminate and provides short electrical high-speed signal paths. With our approach, the electro-optical package becomes a compact electro-optical module with integrated polymer waveguides terminated with either optical connectors (e.g., at the card edge) or with an identical assembly for a second processor on the board. Consequently, no costly subassemblies and connectors are needed, and a very high integration density and scalability to virtually arbitrary channel counts and towards very high data rates (20+ Gbps) become possible. Future cost targets of much less than US$1 per Gbps will be reached by employing standard PCB materials and technologies that are well established in the industry. Moreover, our technology platform has both electrical and optical connectivity and functionality.

High repetition pump-and-probe photoemission spectroscopy based on a compact fiber laser system.

PubMed

Ishida, Y; Otsu, T; Ozawa, A; Yaji, K; Tani, S; Shin, S; Kobayashi, Y

2016-12-01

The paper describes a time-resolved photoemission (TRPES) apparatus equipped with a Yb-doped fiber laser system delivering 1.2-eV pump and 5.9-eV probe pulses at the repetition rate of 95 MHz. Time and energy resolutions are 11.3 meV and ∼310 fs, respectively, the latter is estimated by performing TRPES on a highly oriented pyrolytic graphite (HOPG). The high repetition rate is suited for achieving high signal-to-noise ratio in TRPES spectra, thereby facilitating investigations of ultrafast electronic dynamics in the low pump fluence (p) region. TRPES of polycrystalline bismuth (Bi) at p as low as 30 nJ/mm 2 is demonstrated. The laser source is compact and is docked to an existing TRPES apparatus based on a 250-kHz Ti:sapphire laser system. The 95-MHz system is less prone to space-charge broadening effects compared to the 250-kHz system, which we explicitly show in a systematic probe-power dependency of the Fermi cutoff of polycrystalline gold. We also describe that the TRPES response of an oriented Bi(111)/HOPG sample is useful for fine-tuning the spatial overlap of the pump and probe beams even when p is as low as 30 nJ/mm 2 .

24-26  GHz radio-over-fiber and free-space optics for fifth-generation systems.

PubMed

Bohata, Jan; Komanec, Matěj; Spáčil, Jan; Ghassemlooy, Zabih; Zvánovec, Stanislav; Slavík, Radan

2018-03-01

This Letter outlines radio-over-fiber combined with radio-over-free-space optics (RoFSO) and radio frequency free-space transmission, which is of particular relevance for fifth-generation networks. Here, the frequency band of 24-26 GHz is adopted to demonstrate a low-cost, compact, and high-energy-efficient solution based on the direct intensity modulation and direct detection scheme. For our proof-of-concept demonstration, we use 64 quadrature amplitude modulation with a 100 MHz bandwidth. We assess the link performance by exposing the RoFSO section to atmospheric turbulence conditions. Further, we show that the measured minimum error vector magnitude (EVM) is 4.7% and also verify that the proposed system with the free-space-optics link span of 100 m under strong turbulence can deliver an acceptable EVM of <9% with signal-to-noise ratio levels of 22 dB and 10 dB with and without turbulence, respectively.

Utilizing the Southwest Ultraviolet Imaging System (SwUIS) on the International Space Station

NASA Astrophysics Data System (ADS)

Schindhelm, Eric; Stern, S. Alan; Ennico-Smith, Kimberly

2013-09-01

We present the Southwest Ultraviolet Imaging System (SwUIS), a compact, low-cost instrument designed for remote sensing observations from a manned platform in space. It has two chief configurations; a high spatial resolution mode with a 7-inch Maksutov-Cassegrain telescope, and a large field-of-view camera mode using a lens assembly. It can operate with either an intensified CCD or an electron multiplying CCD camera. Interchangeable filters and lenses enable broadband and narrowband imaging at UV/visible/near-infrared wavelengths, over a range of spatial resolution. SwUIS has flown previously on Space Shuttle flights STS-85 and STS-93, where it recorded multiple UV images of planets, comets, and vulcanoids. We describe the instrument and its capabilities in detail. The SWUIS's broad wavelength coverage and versatile range of hardware configurations make it an attractive option for use as a facility instrument for Earth science and astronomical imaging investigations aboard the International Space Station.

Finite spaces and schemes

NASA Astrophysics Data System (ADS)

Sancho de Salas, Fernando

2017-12-01

A ringed finite space is a ringed space whose underlying topological space is finite. The category of ringed finite spaces contains, fully faithfully, the category of finite topological spaces and the category of affine schemes. Any ringed space, endowed with a finite open covering, produces a ringed finite space. We introduce the notions of schematic finite space and schematic morphism, showing that they behave, with respect to quasi-coherence, like schemes and morphisms of schemes do. Finally, we construct a fully faithful and essentially surjective functor from a localization of a full subcategory of the category of schematic finite spaces and schematic morphisms to the category of quasi-compact and quasi-separated schemes.

Soft connectedness of soft topological space

NASA Astrophysics Data System (ADS)

Mishra, Sanjay

2017-07-01

Recently, Shabir and Naz in [4] introduced the notion of Soft Topological Spaces (STS). They defined and studied about soft topology on the collection τ of soft sets over X. After the initiation of soft topological space many researcher developed its basic theory as like soft continuity, soft compactness and soft countability. Our main objective in this paper is to study the soft connectedness properties of soft topological space and also establish relations of soft connectedness with other properties of STS.

High-gradient low-β accelerating structure using the first negative spatial harmonic of the fundamental mode

NASA Astrophysics Data System (ADS)

Kutsaev, Sergey V.; Agustsson, Ronald; Boucher, Salime; Fischer, Richard; Murokh, Alex; Mustapha, Brahim; Nassiri, Alireza; Ostroumov, Peter N.; Plastun, Alexander; Savin, Evgeny; Smirnov, Alexander Yu.

2017-12-01

The development of high-gradient accelerating structures for low-β particles is the key for compact hadron linear accelerators. A particular example of such a machine is a hadron therapy linac, which is a promising alternative to cyclic machines, traditionally used for cancer treatment. Currently, the practical utilization of linear accelerators in radiation therapy is limited by the requirement to be under 50 m in length. A usable device for cancer therapy should produce 200-250 MeV protons and/or 400 - 450 MeV /u carbon ions, which sets the requirement of having 35 MV /m average "real-estate gradient" or gradient per unit of actual accelerator length, including different accelerating sections, focusing elements and beam transport lines, and at least 50 MV /m accelerating gradients in the high-energy section of the linac. Such high accelerating gradients for ion linacs have recently become feasible for operations at S-band frequencies. However, the reasonable application of traditional S-band structures is practically limited to β =v /c >0.4 . However, the simulations show that for lower phase velocities, these structures have either high surface fields (>200 MV /m ) or low shunt impedances (<35 M Ω /m ). At the same time, a significant (˜10 % ) reduction in the linac length can be achieved by using the 50 MV /m structures starting from β ˜0.3 . To address this issue, we have designed a novel radio frequency structure where the beam is synchronous with the higher spatial harmonic of the electromagnetic field. In this paper, we discuss the principles of this approach, the related beam dynamics and especially the electromagnetic and thermomechanical designs of this novel structure. Besides the application to ion therapy, the technology described in this paper can be applied to future high gradient normal conducting ion linacs and high energy physics machines, such as a compact hadron collider. This approach preserves linac compactness in settings with limited space availability.

Projective loop quantum gravity. I. State space

NASA Astrophysics Data System (ADS)

Lanéry, Suzanne; Thiemann, Thomas

2016-12-01

Instead of formulating the state space of a quantum field theory over one big Hilbert space, it has been proposed by Kijowski to describe quantum states as projective families of density matrices over a collection of smaller, simpler Hilbert spaces. Beside the physical motivations for this approach, it could help designing a quantum state space holding the states we need. In a latter work by Okolów, the description of a theory of Abelian connections within this framework was developed, an important insight being to use building blocks labeled by combinations of edges and surfaces. The present work generalizes this construction to an arbitrary gauge group G (in particular, G is neither assumed to be Abelian nor compact). This involves refining the definition of the label set, as well as deriving explicit formulas to relate the Hilbert spaces attached to different labels. If the gauge group happens to be compact, we also have at our disposal the well-established Ashtekar-Lewandowski Hilbert space, which is defined as an inductive limit using building blocks labeled by edges only. We then show that the quantum state space presented here can be thought as a natural extension of the space of density matrices over this Hilbert space. In addition, it is manifest from the classical counterparts of both formalisms that the projective approach allows for a more balanced treatment of the holonomy and flux variables, so it might pave the way for the development of more satisfactory coherent states.

Atomistic Structure of Mineral Nano-aggregates from Simulated Compaction and Dewatering.

PubMed

Ho, Tuan Anh; Greathouse, Jeffery A; Wang, Yifeng; Criscenti, Louise J

2017-11-10

The porosity of clay aggregates is an important property governing chemical reactions and fluid flow in low-permeability geologic formations and clay-based engineered barrier systems. Pore spaces in clays include interlayer and interparticle pores. Under compaction and dewatering, the size and geometry of such pore spaces may vary significantly (sub-nanometer to microns) depending on ambient physical and chemical conditions. Here we report a molecular dynamics simulation method to construct a complex and realistic clay-like nanoparticle aggregate with interparticle pores and grain boundaries. The model structure is then used to investigate the effect of dewatering and water content on micro-porosity of the aggregates. The results suggest that slow dewatering would create more compact aggregates compared to fast dewatering. Furthermore, the amount of water present in the aggregates strongly affects the particle-particle interactions and hence the aggregate structure. Detailed analyses of particle-particle and water-particle interactions provide a molecular-scale view of porosity and texture development of the aggregates. The simulation method developed here may also aid in modeling the synthesis of nanostructured materials through self-assembly of nanoparticles.

Atomistic Structure of Mineral Nano-aggregates from Simulated Compaction and Dewatering

DOE PAGES

Ho, Tuan Anh; Greathouse, Jeffery A.; Wang, Yifeng; ...

2017-11-10

The porosity of clay aggregates is an important property governing chemical reactions and fluid flow in low-permeability geologic formations and clay-based engineered barrier systems. Pore spaces in clays include interlayer and interparticle pores. Under compaction and dewatering, the size and geometry of such pore spaces may vary significantly (sub-nanometer to microns) depending on ambient physical and chemical conditions. Here we report a molecular dynamics simulation method to construct a complex and realistic clay-like nanoparticle aggregate with interparticle pores and grain boundaries. The model structure is then used to investigate the effect of dewatering and water content on micro-porosity of themore » aggregates. The results suggest that slow dewatering would create more compact aggregates compared to fast dewatering. Furthermore, the amount of water present in the aggregates strongly affects the particle-particle interactions and hence the aggregate structure. Detailed analyses of particle-particle and water-particle interactions provide a molecular-scale view of porosity and texture development of the aggregates. The simulation method developed here may also aid in modeling the synthesis of nanostructured materials through self-assembly of nanoparticles.« less

Stabilized diode seed laser for flight and space-based remote lidar sensing applications

NASA Astrophysics Data System (ADS)

McNeil, Shirley; Pandit, Pushkar; Battle, Philip; Rudd, Joe; Hovis, Floyd

2017-08-01

AdvR, through support of the NASA SBIR program, has developed fiber-based components and sub-systems that are routinely used on NASA's airborne missions, and is now developing an environmentally hardened, diode-based, locked wavelength, seed laser for future space-based high spectral resolution lidar applications. The seed laser source utilizes a fiber-coupled diode laser, a fiber-coupled, calibrated iodine reference module to provide an absolute wavelength reference, and an integrated, dual-element, nonlinear optical waveguide component for second harmonic generation, spectral formatting and wavelength locking. The diode laser operates over a range close to 1064.5 nm, provides for stabilization of the seed to the desired iodine transition and allows for a highly-efficient, fully-integrated seed source that is well-suited for use in airborne and space-based environments. A summary of component level environmental testing and spectral purity measurements with a seeded Nd:YAG laser will be presented. A direct-diode, wavelength-locked seed laser will reduce the overall size weight and power (SWaP) requirements of the laser transmitter, thus directly addressing the need for developing compact, efficient, lidar component technologies for use in airborne and space-based environments.

The FAST (FRC Acceleration Space Thruster) Experiment

NASA Technical Reports Server (NTRS)

Martin, Adam; Eskridge, R.; Lee, M.; Richeson, J.; Smith, J.; Thio, Y. C. F.; Slough, J.; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

The Field Reverse Configuration (FRC) is a magnetized plasmoid that has been developed for use in magnetic confinement fusion. Several of its properties suggest that it may also be useful as a thruster for in-space propulsion. The FRC is a compact toroid that has only poloidal field, and is characterized by a high plasma beta = (P)/(B (sup 2) /2Mu0), the ratio of plasma pressure to magnetic field pressure, so that it makes efficient use of magnetic field to confine a plasma. In an FRC thruster, plasmoids would be repetitively formed and accelerated to high velocity; velocities of = 250 km/s (Isp = 25,000s) have already been achieved in fusion experiments. The FRC is inductively formed and accelerated, and so is not subject to the problem of electrode erosion. As the plasmoid may be accelerated over an extended length, it can in principle be made very efficient. And the achievable jet powers should be scalable to the MW range. A 10 kW thruster experiment - FAST (FRC Acceleration Space Thruster) has just started at the Marshall Space Flight Center. The design of FAST and the status of construction and operation will be presented.

Interparticle spacing and structural ordering in superlattice PbS nanocrystal solids undergoing ligand exchange

DOE PAGES

Weidman, Mark C.; Yager, Kevin G.; Tisdale, William A.

2014-12-12

Controlling the interparticle spacing in quantum dot (QD) thin films is the most readily accessible way to control transport rates between neighboring QDs and a critical component of device optimization. Here, we use X-ray scattering measurements to accurately measure the interparticle spacing in films of highly monodisperse lead sulfide (PbS) QDs that have undergone a variety of device-relevant ligand exchanges. We tabulate these values for use in simulations and data analysis. We find that monothiol and dithiol ligand species typically result in interparticle spacing values that are equal to the length of a single monothiol or dithiol ligand. Additionally, wemore » find that spin-coating a thick film of QDs followed by a long-duration ligand exchange results in a more complete ligand exchange than spin-coating many thin layers with short-duration ligand exchanges in between. The former method also preserves a remarkable degree of the long-range ordering that was present in the film prior to ligand exchange. These results shed light on ways to produce highly-ordered QD solids with compact and functional ligands, which could lead to enhanced interdot coupling and transport phenomena.« less

MUSE spectroscopy and deep observations of a unique compact JWST target, lensing cluster CLIO

NASA Astrophysics Data System (ADS)

Griffiths, Alex; Conselice, Christopher J.; Alpaslan, Mehmet; Frye, Brenda L.; Diego, Jose M.; Zitrin, Adi; Yan, Haojing; Ma, Zhiyuan; Barone-Nugent, Robert; Bhatawdekar, Rachana; Driver, Simon P.; Robotham, Aaron S. G.; Windhorst, Rogier A.; Wyithe, J. Stuart B.

2018-04-01

We present the results of a VLT MUSE/FORS2 and Spitzer survey of a unique compact lensing cluster CLIO at z = 0.42, discovered through the GAMA survey using spectroscopic redshifts. Compact and massive clusters such as this are understudied, but provide a unique prospective on dark matter distributions and for finding background lensed high-z galaxies. The CLIO cluster was identified for follow-up observations due to its almost unique combination of high-mass and dark matter halo concentration, as well as having observed lensing arcs from ground-based images. Using dual band optical and infra-red imaging from FORS2 and Spitzer, in combination with MUSE optical spectroscopy we identify 89 cluster members and find background sources out to z = 6.49. We describe the physical state of this cluster, finding a strong correlation between environment and galaxy spectral type. Under the assumption of an NFW profile, we measure the total mass of CLIO to be M200 = (4.49 ± 0.25) × 1014 M⊙. We build and present an initial strong-lensing model for this cluster, and measure a relatively low intracluster light (ICL) fraction of 7.21 ± 1.53 per cent through galaxy profile fitting. Due to its strong potential for lensing background galaxies and its low ICL, the CLIO cluster will be a target for our 110 h James Webb Space Telescope `Webb Medium-Deep Field' (WMDF) GTO program.

The development of compact electroactive polymer actuators suitable for use in full page Braille displays

NASA Astrophysics Data System (ADS)

Gorny, Lee J.; Zellers, Brian C.; Lin, Minren; Liu, Sheng; Zhang, Qiming M.

2010-04-01

Piezoceramic actuators, presently used in commercial Braille displays, are limited by the material's relatively small strain and brittle nature. For this reason, it is a challenge to develop full page, compact, graphic Braille displays that are affordable. A newly developed material composed of P(VDF-TrFE-CFE) terpolymer blended with 5% P(VDF-CTFE) electrostrictive actuators exhibits large strains (~5% at 150V/μm), fast actuation (>5 mm/s), and has a relatively high elastic modulus (1.2 GPa). This material exhibits more than double the elastic energy density and a 50% higher modulus of the original electrostrictive terpolymer. Hence, the potential for viable actuators in compact, full page Braille displays is greater than ever, provided actuators can be manufactured reliably in quantity. This talk presents recent work in scaling production of such rolled actuators. Actuators extend .5 mm, are confined to the 2.5 mm grid spacing of conventional Braille text, generate >0.5 N force and operate at less than 200V, thus meeting the primary requirements for a commercialized Braille display. To manufacture these actuators, cast films are stretched using a roll-to-roll zone drawing machine that is capable of producing quantities of 2 μm thick film with high quality. What follows is a discussion of this machine, the roll-to-roll film stretching process and an assessment of the resulting stretched film for use as linear strain actuators, like those used in our Braille cell.

Dark Matter under the Microscope: Constraining Compact Dark Matter with Caustic Crossing Events

NASA Astrophysics Data System (ADS)

Diego, Jose M.; Kaiser, Nick; Broadhurst, Tom; Kelly, Patrick L.; Rodney, Steve; Morishita, Takahiro; Oguri, Masamune; Ross, Timothy W.; Zitrin, Adi; Jauzac, Mathilde; Richard, Johan; Williams, Liliya; Vega-Ferrero, Jesus; Frye, Brenda; Filippenko, Alexei V.

2018-04-01

A galaxy cluster acts as a cosmic telescope over background galaxies but also as a cosmic microscope magnifying the imperfections of the lens. The diverging magnification of lensing caustics enhances the microlensing effect of substructure present within the lensing mass. Fine-scale structure can be accessed as a moving background source brightens and disappears when crossing these caustics. The recent discovery of a distant lensed star near the Einstein radius of the galaxy cluster MACSJ1149.5+2223 allows a rare opportunity to reach subsolar-mass microlensing through a supercritical column of cluster matter. Here we compare these observations with high-resolution ray-tracing simulations that include stellar microlensing set by the observed intracluster starlight and also primordial black holes that may be responsible for the recently observed LIGO events. We explore different scenarios with microlenses from the intracluster medium and black holes, including primordial ones, and examine strategies to exploit these unique alignments. We find that the best constraints on the fraction of compact dark matter (DM) in the small-mass regime can be obtained in regions of the cluster where the intracluster medium plays a negligible role. This new lensing phenomenon should be widespread and can be detected within modest-redshift lensed galaxies so that the luminosity distance is not prohibitive for detecting individual magnified stars. High-cadence Hubble Space Telescope monitoring of several such optimal arcs will be rewarded by an unprecedented mass spectrum of compact objects that can contribute to uncovering the nature of DM.

Scoping study for compact high-field superconducting net energy tokamaks

NASA Astrophysics Data System (ADS)

Mumgaard, R. T.; Greenwald, M.; Freidberg, J. P.; Wolfe, S. M.; Hartwig, Z. S.; Brunner, D.; Sorbom, B. N.; Whyte, D. G.

2016-10-01

The continued development and commercialization of high temperature superconductors (HTS) may enable the construction of compact, net-energy tokamaks. HTS, in contrast to present generation low temperature superconductors, offers improved performance in high magnetic fields, higher current density, stronger materials, higher temperature operation, and simplified assembly. Using HTS along with community-consensus confinement physics (H98 =1) may make it possible to achieve net-energy (Q>1) or burning plasma conditions (Q>5) in DIII-D or ASDEX-U sized, conventional aspect ratio tokamaks. It is shown that, by operating at high plasma current and density enabled by the high magnetic field (B>10T), the required triple products may be achieved at plasma volumes under 20m3, major radii under 2m, with external heating powers under 40MW. This is at the scale of existing devices operated by laboratories, universities and companies. The trade-offs in the core heating, divertor heat exhaust, sustainment, stability, and proximity to known plasma physics limits are discussed in the context of the present tokamak experience base and the requirements for future devices. The resulting HTS-based design space is compared and contrasted to previous studies on high-field copper experiments with similar missions. The physics exploration conducted with such HTS devices could decrease the real and perceived risks of ITER exploitation, and aid in quickly developing commercially-applicable tokamak pilot plants and reactors.

A telescopic cinema sound camera for observing high altitude aerospace vehicles

NASA Astrophysics Data System (ADS)

Slater, Dan

2014-09-01

Rockets and other high altitude aerospace vehicles produce interesting visual and aural phenomena that can be remotely observed from long distances. This paper describes a compact, passive and covert remote sensing system that can produce high resolution sound movies at >100 km viewing distances. The telescopic high resolution camera is capable of resolving and quantifying space launch vehicle dynamics including plume formation, staging events and payload fairing jettison. Flight vehicles produce sounds and vibrations that modulate the local electromagnetic environment. These audio frequency modulations can be remotely sensed by passive optical and radio wave detectors. Acousto-optic sensing methods were primarily used but an experimental radioacoustic sensor using passive micro-Doppler radar techniques was also tested. The synchronized combination of high resolution flight vehicle imagery with the associated vehicle sounds produces a cinema like experience that that is useful in both an aerospace engineering and a Hollywood film production context. Examples of visual, aural and radar observations of the first SpaceX Falcon 9 v1.1 rocket launch are shown and discussed.

Preparation of ultra-thin and high-quality WO{sub 3} compact layers and comparision of WO{sub 3} and TiO{sub 2} compact layer thickness in planar perovskite solar cells

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

Zhang, Jincheng; Shi, Chengwu, E-mail: shicw506@foxmail.com; Chen, Junjun

2016-06-15

In this paper, the ultra-thin and high-quality WO{sub 3} compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO{sub 3} and TiO{sub 2} compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO{sub 2} compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO{sub 3} and TiO{sub 2} compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO{submore » 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. - Graphical abstract: The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. Display Omitted - Highlights: • Preparation of ultra-thin and high-quality WO{sub 3} compact layers. • Perovskite solar cell with 15 nm-thick WO{sub 3} compact layer achieved PCE of 10.14%. • Perovskite solar cell with 60 nm-thick TiO{sub 2} compact layer achieved PCE of 12.64%.« less

A compact high brightness laser synchrotron light source for medical applications

NASA Astrophysics Data System (ADS)

Nakajima, Kazuhisa

1999-07-01

The present high-brightness hard X-ray sources have been developed as third generation synchrotron light sources based on large high energy electron storage rings and magnetic undulators. Recently availability of compact terawatt lasers arouses a great interest in the use of lasers as undulators. The laser undulator concept makes it possible to construct an attractive compact synchrotron radiation source which has been proposed as a laser synchrotron light source. This paper proposes a compact laser synchrotron light source for mediacal applications, such as an intravenous coronary angiography and microbeam therapy.

Software Correlator for Radioastron Mission

NASA Astrophysics Data System (ADS)

Likhachev, Sergey F.; Kostenko, Vladimir I.; Girin, Igor A.; Andrianov, Andrey S.; Rudnitskiy, Alexey G.; Zharov, Vladimir E.

In this paper, we discuss the characteristics and operation of Astro Space Center (ASC) software FX correlator that is an important component of space-ground interferometer for Radioastron project. This project performs joint observations of compact radio sources using 10m space radio telescope (SRT) together with ground radio telescopes at 92, 18, 6 and 1.3 cm wavelengths. In this paper, we describe the main features of space-ground VLBI data processing of Radioastron project using ASC correlator. Quality of implemented fringe search procedure provides positive results without significant losses in correlated amplitude. ASC Correlator has a computational power close to real time operation. The correlator has a number of processing modes: “Continuum”, “Spectral Line”, “Pulsars”, “Giant Pulses”,“Coherent”. Special attention is paid to peculiarities of Radioastron space-ground VLBI data processing. The algorithms of time delay and delay rate calculation are also discussed, which is a matter of principle for data correlation of space-ground interferometers. During five years of Radioastron SRT successful operation, ASC correlator showed high potential of satisfying steady growing needs of current and future ground and space VLBI science. Results of ASC software correlator operation are demonstrated.

Roles of biology, chemistry, and physics in soil macroaggregate formation and stabilization

USDA-ARS?s Scientific Manuscript database

Soil functions or ecosystem services depend on the distribution of macro- (= 0.25 mm) and micro- (< 0.25 mm) aggregates and open space between aggregates. It is the arrangement of the aggregates and pore space which allows air and water movement in and out of soil; reduces compaction; and stimulates...

Compactor for Space Toilet

NASA Technical Reports Server (NTRS)

Autrey, David (Inventor); Morrison, Terrell Lee (Inventor); Kaufman, Cory (Inventor)

2017-01-01

A toilet for use on a space vehicle has a toilet bowl having a storage canister at a remote end for receiving human waste. The compactor includes a cable connected to a lever which pulls the cable in a direction forcing the compactor into the storage canister to compact the captured waste when the lever is actuated.

Compact Video Microscope Imaging System Implemented in Colloid Studies

NASA Technical Reports Server (NTRS)

McDowell, Mark

2002-01-01

Long description Photographs showing fiber-optic light source, microscope and charge-coupled discharge (CCD) camera head connected to camera body, CCD camera body feeding data to image acquisition board in PC, and Cartesian robot controlled via PC board. The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. CMIS can be used in situ with a minimum amount of user intervention. This system can scan, find areas of interest in, focus on, and acquire images automatically. Many multiple-cell experiments require microscopy for in situ observations; this is feasible only with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control. The software also has a user-friendly interface, which can be used independently of the hardware for further post-experiment analysis. CMIS has been successfully developed in the SML Laboratory at the NASA Glenn Research Center and adapted for use for colloid studies and is available for telescience experiments. The main innovations this year are an improved interface, optimized algorithms, and the ability to control conventional full-sized microscopes in addition to compact microscopes. The CMIS software-hardware interface is being integrated into our SML Analysis package, which will be a robust general-purpose image-processing package that can handle over 100 space and industrial applications.

ɛ-connectedness, finite approximations, shape theory and coarse graining in hyperspaces

NASA Astrophysics Data System (ADS)

Alonso-Morón, Manuel; Cuchillo-Ibanez, Eduardo; Luzón, Ana

2008-12-01

We use upper semifinite hyperspaces of compacta to describe ε-connectedness and to compute homology from finite approximations. We find a new connection between ε-connectedness and the so-called Shape Theory. We construct a geodesically complete R-tree, by means of ε-components at different resolutions, whose behavior at infinite captures the topological structure of the space of components of a given compact metric space. We also construct inverse sequences of finite spaces using internal finite approximations of compact metric spaces. These sequences can be converted into inverse sequences of polyhedra and simplicial maps by means of what we call the Alexandroff-McCord correspondence. This correspondence allows us to relate upper semifinite hyperspaces of finite approximation with the Vietoris-Rips complexes of such approximations at different resolutions. Two motivating examples are included in the introduction. We propose this procedure as a different mathematical foundation for problems on data analysis. This process is intrinsically related to the methodology of shape theory. This paper reinforces Robins’s idea of using methods from shape theory to compute homology from finite approximations.

Coherent states for quantum compact groups

NASA Astrophysics Data System (ADS)

Jurĉo, B.; Ŝťovíĉek, P.

1996-12-01

Coherent states are introduced and their properties are discussed for simple quantum compact groups A l, Bl, Cl and D l. The multiplicative form of the canonical element for the quantum double is used to introduce the holomorphic coordinates on a general quantum dressing orbit. The coherent state is interpreted as a holomorphic function on this orbit with values in the carrier Hilbert space of an irreducible representation of the corresponding quantized enveloping algebra. Using Gauss decomposition, the commutation relations for the holomorphic coordinates on the dressing orbit are derived explicitly and given in a compact R-matrix formulation (generalizing this way the q-deformed Grassmann and flag manifolds). The antiholomorphic realization of the irreducible representations of a compact quantum group (the analogue of the Borel-Weil construction) is described using the concept of coherent state. The relation between representation theory and non-commutative differential geometry is suggested.

Ultra-precision fabrication of high density micro-optical backbone interconnections for data center and mobile application

NASA Astrophysics Data System (ADS)

Lohmann, U.; Jahns, J.; Wagner, T.; Werner, C.

2012-10-01

A microoptical 3D interconnection scheme and fabricated samples of this fiberoptical multi-channel interconnec- tion with an actual capacity of 144 channels were shown. Additionally the aspects of micrometer-fabrication of such microoptical interconnection modules in the view of alignment-tolerances were considered. For the realiza- tion of the interconnection schemes, the approach of planar-integrated free space optics (PIFSO) is used with its well known advantages. This approach offers the potential for complex interconnectivity, and yet compact size.

Development of Advanced Seed Laser Modules for Lidar and Spectroscopy Applications

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Rosiewicz, Alex; Coleman, Steven M.

2013-01-01

We report on recent progress made in the development of highly compact, single mode, distributed feedback laser (DFB) seed laser modules for lidar and spectroscopy applications from space based platforms. One of the intended application of this technology is in the NASA's Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The DFB laser modules operating at 1571 nm and 1262 nm have advanced current and temperature drivers built into them. A combination of temperature and current tuning allows coarse and fine adjustment of the diode wavelengths.

MoonBEAM: Gamma-Ray Burst Detectors on SmallSAT

NASA Technical Reports Server (NTRS)

Hui, C. M.; Briggs, M. S.; Goldstein, A. M.; Jenke, P. A.; Kocevski, D.; Wilson-Hodge, C. A.

2018-01-01

Moon Burst Energetics All-sky Monitor (MoonBEAM) is a CubeSat concept of deploying gamma-ray detectors in cislunar space to improve localization precision for gamma-ray bursts by utilizing the light travel time difference between a spacecraft in Earth and cislunar orbit. MoonBEAM is designed with high TRL components to be flight ready. This instrument would probe the extreme processes in cosmic collision of compact objects and facilitate multi-messenger time-domain astronomy to explore the end of stellar life cycles and black hole formations.

An introduction to the mechanics of DNA.

PubMed

Travers, A A; Thompson, J M T

2004-07-15

This article gives an overview of recent research on the mechanical properties and spatial deformations of the DNA molecule. Globally the molecule behaves like a uniform elastic rod, and its twisting and writhing govern its compaction and packaging within a cell. Meanwhile high mechanical stresses can induce structural transitions of DNA giving, for example, a phase diagram in the space of the applied tension and torque. Locally, the mechanical properties vary according to the local sequence organization. These variations play a vital role in the biological functioning of the molecule.

Calocube-A highly segmented calorimeter for a space based experiment

NASA Astrophysics Data System (ADS)

D`Alessandro, R.; Adriani, O.; Agnesi, A.; Albergo, S.; Auditore, L.; Basti, A.; Berti, E.; Bigongiari, G.; Bonechi, L.; Bonechi, S.; Bongi, M.; Bonvicini, V.; Bottai, S.; Brogi, P.; Carotenuto, G.; Castellini, G.; Cattaneo, P. W.; Cauz, D.; Chiari, M.; Daddi, N.; Detti, S.; Fasoli, M.; Finetti, N.; Gregorio, A.; Lenzi, P.; Maestro, P.; Marrocchesi, P. S.; Miritello, M.; Mori, N.; Pacini, L.; Papini, P.; Pauletta, G.; Pirzio, F.; Rappazzo, G. F.; Rappoldi, A.; Ricciarini, S.; Santi, L. G.; Spillantini, P.; Starodubtsev, O.; Suh, J. E.; Sulaj, A.; Tiberio, A.; Tricomi, A.; Trifiro, A.; Trimarchi, M.; Vannuccini, E.; Vedda, A.; Zampa, G.; Zampa, N.; Zerbo, B.

2016-07-01

Future research in High Energy Cosmic Ray Physics concerns fundamental questions on their origin, acceleration mechanism, and composition. Unambiguous measurements of the energy spectra and of the composition of cosmic rays at the "knee" region could provide some of the answers to the above questions. Only ground based observations, which rely on sophisticated models describing high energy interactions in the earth's atmosphere, have been possible so far due to the extremely low particle rates at these energies. A calorimeter based space experiment can provide not only flux measurements but also energy spectra and particle identification, especially when coupled to a dE/dx measuring detector, and thus overcome some of the limitations plaguing ground based experiments. For this to be possible very large acceptances are needed if enough statistic is to be collected in a reasonable time. This contrasts with the lightness and compactness requirements for space based experiments. A novel idea in calorimetry is discussed here which addresses these issues while limiting the mass and volume of the detector. In fact a small prototype is currently being built and tested with ions. In this paper the results obtained will be presented in light of the simulations performed.

Demonstration of Space Optical Transmitter Development for Multiple High Frequency Bands

NASA Technical Reports Server (NTRS)

Nguyen, Hung; Simons, Rainee; Wintucky, Edwin; Freeman, Jon

2013-01-01

As the demand for multiple radio frequency carrier bands continues to grow in space communication systems, the design of a cost-effective compact optical transmitter that is capable of transmitting selective multiple RF bands is of great interest, particularly for NASA Space Communications Network Programs. This paper presents experimental results that demonstrate the feasibility of a concept based on an optical wavelength division multiplexing (WDM) technique that enables multiple microwave bands with different modulation formats and bandwidths to be combined and transmitted all in one unit, resulting in many benefits to space communication systems including reduced size, weight and complexity with corresponding savings in cost. Experimental results will be presented including the individual received RF signal power spectra for the L, C, X, Ku, Ka, and Q frequency bands, and measurements of the phase noise associated with each RF frequency. Also to be presented is a swept RF frequency power spectrum showing simultaneous multiple RF frequency bands transmission. The RF frequency bands in this experiment are among those most commonly used in NASA space environment communications.

Deployable robotic woven wire structures and joints for space applications

NASA Technical Reports Server (NTRS)

Shahinpoor, MO; Smith, Bradford

1991-01-01

Deployable robotic structures are basically expandable and contractable structures that may be transported or launched to space in a compact form. These structures may then be intelligently deployed by suitable actuators. The deployment may also be done by means of either airbag or spring-loaded typed mechanisms. The actuators may be pneumatic, hydraulic, ball-screw type, or electromagnetic. The means to trigger actuation may be on-board EPROMS, programmable logic controllers (PLCs) that trigger actuation based on some input caused by the placement of the structure in the space environment. The actuation may also be performed remotely by suitable remote triggering devices. Several deployable woven wire structures are examined. These woven wire structures possess a unique form of joint, the woven wire joint, which is capable of moving and changing its position and orientation with respect to the structure itself. Due to the highly dynamic and articulate nature of these joints the 3-D structures built using them are uniquely and highly expandable, deployable, and dynamic. The 3-D structure naturally gives rise to a new generation of deployable three-dimensional spatial structures.

Feasibility Study For A Spaceborne Ozone/Aerosol Lidar System

NASA Technical Reports Server (NTRS)

Campbell, Richard E.; Browell, Edward V.; Ismail, Syed; Dudelzak, Alexander E.; Carswell, Allan I.; Ulitsky, Arkady

1997-01-01

Because ozone provides a shield against harmful ultraviolet radiation, determines the temperature profile in the stratosphere, plays important roles in tropospheric chemistry and climate, and is a health risk near the surface, changes in natural ozone layers at different altitudes and their global impact are being intensively researched. Global ozone coverage is currently provided by passive optical and microwave satellite sensors that cannot deliver high spatial resolution measurements and have particular limitations in the troposphere. Vertical profiling DIfferential Absorption Lidars (DIAL) have shown excellent range-resolved capabilities, but these systems have been large, inefficient, and have required continuous technical attention for long term operations. Recently, successful, autonomous DIAL measurements have been performed from a high-altitude aircraft (LASE - Lidar Atmospheric Sensing Experiment), and a space-qualified aerosol lidar system (LITE - Laser In-space Technology Experiment) has performed well on Shuttle. Based on the above successes, NASA and the Canadian Space Agency are jointly studying the feasibility of developing ORACLE (Ozone Research with Advanced Cooperative Lidar Experiments), an autonomously operated, compact DIAL instrument to be placed in orbit using a Pegasus class launch vehicle.

Bergman spaces of natural G-manifolds☆

PubMed Central

Della Sala, Giuseppe; Perez, Joe J.

2013-01-01

Let G be a unimodular Lie group, X a compact manifold with boundary, and M the total space of a principal bundle G→M→X so that M is also a strongly pseudoconvex complex manifold. In this work, we show that if there exists a point p∈bM such that TpG is contained in the complex tangent space TpcbM of bM at p, then the Bergman space of M is large. Natural examples include the gauged G-complexifications of Heinzner, Huckleberry, and Kutzschebauch. PMID:24222924

Space Station Live: Everythings Coming up Veggie

NASA Image and Video Library

2016-04-13

NASA Commentator Lori Meggs at the Marshall Space Flight Center talks about the latest work of the Veggie experiment on board the International Space Station with Gioia Massa, the Veggie project scientist. The experimental compact greenhouse has been used successfully to grow two crops of lettuce and a crop of zinnias, demonstrating an ability to grow crops in space that could be very useful for future exploration missions out into the solar systems. More tests are on the agenda as specialists improve the capabilities of the system.

Compactness and robustness: Applications in the solution of integral equations for chemical kinetics and electromagnetic scattering

NASA Astrophysics Data System (ADS)

Zhou, Yajun

This thesis employs the topological concept of compactness to deduce robust solutions to two integral equations arising from chemistry and physics: the inverse Laplace problem in chemical kinetics and the vector wave scattering problem in dielectric optics. The inverse Laplace problem occurs in the quantitative understanding of biological processes that exhibit complex kinetic behavior: different subpopulations of transition events from the "reactant" state to the "product" state follow distinct reaction rate constants, which results in a weighted superposition of exponential decay modes. Reconstruction of the rate constant distribution from kinetic data is often critical for mechanistic understandings of chemical reactions related to biological macromolecules. We devise a "phase function approach" to recover the probability distribution of rate constants from decay data in the time domain. The robustness (numerical stability) of this reconstruction algorithm builds upon the continuity of the transformations connecting the relevant function spaces that are compact metric spaces. The robust "phase function approach" not only is useful for the analysis of heterogeneous subpopulations of exponential decays within a single transition step, but also is generalizable to the kinetic analysis of complex chemical reactions that involve multiple intermediate steps. A quantitative characterization of the light scattering is central to many meteoro-logical, optical, and medical applications. We give a rigorous treatment to electromagnetic scattering on arbitrarily shaped dielectric media via the Born equation: an integral equation with a strongly singular convolution kernel that corresponds to a non-compact Green operator. By constructing a quadratic polynomial of the Green operator that cancels out the kernel singularity and satisfies the compactness criterion, we reveal the universality of a real resonance mode in dielectric optics. Meanwhile, exploiting the properties of compact operators, we outline the geometric and physical conditions that guarantee a robust solution to the light scattering problem, and devise an asymptotic solution to the Born equation of electromagnetic scattering for arbitrarily shaped dielectric in a non-perturbative manner.

Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

NASA Astrophysics Data System (ADS)

Izotov, Y. I.; Schaerer, D.; Thuan, T. X.; Worseck, G.; Guseva, N. G.; Orlitová, I.; Verhamme, A.

2016-10-01

Following our first detection reported in Izotov et al., we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope. These galaxies, at redshifts of z ˜ 0.3, are characterized by high emission-line flux ratios [O III] λ5007/[O II] λ3727 ≳ 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ˜6-13 per cent, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Ly α emission lines are detected in the spectra of all four galaxies, compatible with predictions for LyC leakers. We find escape fractions of Ly α, fesc(Ly α) ˜ 20-40 per cent, among the highest known for Ly α emitting galaxies. Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the centre and exponential discs in the outskirts with disc scalelengths α in the range ˜0.6-1.4 kpc. Our galaxies are characterized by low metallicity, ˜1/8-1/5 solar, low stellar mass ˜(0.2-4) × 109 M⊙, high star formation rates, SFR ˜ 14-36 M⊙ yr-1, and high SFR densities, Σ ˜ 2-35 M⊙ yr-1 kpc-2. These properties are comparable to those of high-redshift star-forming galaxies. Finally, our observations, combined with our first detection reported in Izotov et al., reveal that a selection for compact star-forming galaxies showing high [O III] λ5007/[O II] λ3727 ratios appears to pick up very efficiently sources with escaping LyC radiation: all five of our selected galaxies are LyC leakers.

Bone histology in extant and fossil penguins (Aves: Sphenisciformes).

PubMed

Ksepka, Daniel T; Werning, Sarah; Sclafani, Michelle; Boles, Zachary M

2015-11-01

Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although cortical lines of arrested growth have been observed in extant penguins, none was observed in any of the current sampled specimens. Therefore, it is likely that even these 'giant' penguin taxa completed their growth cycle without a major pause in bone deposition, implying that they did not undergo a prolonged fasting interval before reaching adult size. © 2015 Anatomical Society.

Bone histology in extant and fossil penguins (Aves: Sphenisciformes)

PubMed Central

Ksepka, Daniel T; Werning, Sarah; Sclafani, Michelle; Boles, Zachary M

2015-01-01

Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although cortical lines of arrested growth have been observed in extant penguins, none was observed in any of the current sampled specimens. Therefore, it is likely that even these ‘giant’ penguin taxa completed their growth cycle without a major pause in bone deposition, implying that they did not undergo a prolonged fasting interval before reaching adult size. PMID:26360700

Urban e-Mobility - Challenges and potential solutions using the example of the "E3W" concept vehicle

NASA Astrophysics Data System (ADS)

Perterer, M.; Martin, P.; Lochner, H.

2014-05-01

Due to the increasing number of people in urban areas, there is a need for affordable individual transportation. Limited space in cities together with the need for a significant reduction of pollution will lead to new mobility concepts in the near future. The aim of these concepts is not replacing the car itself, but to supply an additional personal transportation solution with local zero emission. Therefore, electrical powered vehicle concepts may be used. Due to the limited energy density and high cost of current Li-ion batteries, a significant weight reduction of the vehicle could lead to acceptable range and cost. In order to develop an affordable urban concept, the requirements for this kind of vehicle also have to be adjusted in comparison to conventional cars. This concept, the so called "E3W", combines the advantages of a two-wheeler with those of a four-wheeler, resulting in a lightweight and compact vehicle. This concept accommodates space for two persons with luggage and guarantees a high level of safety including wind and weather protection. The overall measures of this vehicle are smaller than current compact cars and allow therefore better use in cities. In order to fulfill technical and commercial requirements, a load carrying, short fiber reinforced thermoplastic body structure is chosen, combining good weight specific mechanical properties and low production costs. This highly integrated body structure also provides the body cover all in one. Pultruded glass fiber reinforced plastic (GFRP) beams are used as the backbone for the vehicle by carrying the main loads, the front crash structure and the rear swingarm. Finally, two prototypes are built to investigate the driving behavior, proof the concept and the suitability for daily use.

The Star Formation History of the Very Metal-poor Blue Compact Dwarf I Zw 18 from HST/ACS Data

NASA Astrophysics Data System (ADS)

Annibali, F.; Cignoni, M.; Tosi, M.; van der Marel, R. P.; Aloisi, A.; Clementini, G.; Contreras Ramos, R.; Fiorentino, G.; Marconi, M.; Musella, I.

2013-12-01

We have derived the star formation history (SFH) of the blue compact dwarf galaxy I Zw 18 through comparison of deep HST/ACS data with synthetic color-magnitude diagrams (CMDs). A statistical analysis was implemented for the identification of the best-fit SFH and relative uncertainties. We confirm that I Zw 18 is not a truly young galaxy, having started forming stars earlier than ~1 Gyr ago, and possibly at epochs as old as a Hubble time. In I Zw 18's main body we infer a lower limit of ≈2 × 106 M ⊙ for the mass locked up in old stars. I Zw 18's main body has been forming stars very actively during the last ~10 Myr, with an average star formation rate (SFR) as high as ≈1 M ⊙ yr-1 (or ≈2 × 10-5 M ⊙ yr-1 pc-2). On the other hand, the secondary body was much less active at these epochs, in agreement with the absence of significant nebular emission. The high current SFR can explain the very blue colors and the high ionized gas content in I Zw 18, resembling primeval galaxies in the early universe. Detailed chemical evolution models are required to quantitatively check whether the SFH from the synthetic CMDs can explain the low measured element abundances, or if galactic winds with loss of metals are needed. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., for NASA under contract NAS5-26555.

A new space instrumental concept based on dispersive components for the measurement of CO2 concentration in the atmosphere

NASA Astrophysics Data System (ADS)

Pascal, Véronique; Buil, Christian; Cansot, Elodie; Loesel, Jacques; Tauziede, Laurie; Pierangelo, Clémence; Bermudo, François

2017-11-01

Measuring the concentration of greenhouse gases from space is a current challenge. This measurement is achieved via a precise analysis of the signature of chemical gaseous species (CO2, CH4, CO, etc.) in the spectrum of the reflected sunlight. First at all, two families of spectrometers have been studied for the MicroCarb mission. The first family is based on the phenomena of interference between two radiation waves (Michelson Interferometer). The second family is based on the use of dispersive optical components. The second family has been selected for the forthcoming studies in the MicroCarb project. These instruments must have high radiometric and spectral resolutions, in narrow spectral bands, in order to discriminate between absorption lines from various atmospheric chemical species, and to quantify their concentration. This is the case, for example, for the instrument onboard the OCO-2 satellite (NASA/JPL). Our analysis has led us to define a new instrumental concept, based on a dispersive grating spectrometer, with the aim of providing the same accuracy level as the OCO-2, but with a more compact design for accommodation on the Myriade Evolution microsatellite class. This compact design approach will allow us to offer a moderate-cost solution to fulfil mission objectives. Two other studies based on dispersive grating are in progress by CNES prime contractors (ASTRIUM and THALES ALENIA SPACE). A summary of the main specifications of this design will be described, in particular the approach with the so-called "merit function". After a description of such a space instrument, which uses a specific grating component, a preliminary assessment of performances will be presented, including the theoretical calculations and formula. A breadboard implementation of this specific grating has allowed us to show the practicality of this concept and its capabilities. Some results of this breadboard will be described. In addition, an instrument simulator is being developed to validate the performances of this concept. A grating component prototype has been built, and the specifications, together with the expected performances, will be described, in particular the polarisation ratio. Some elements about detectors will be also given regarding their suitability for the mission. This preliminary design is encouraging and shows that such a spectrometer may be compatible with a microsatellite platform (low mass, low power and compact design). Some prospects of improvements will also be considered.

Ultra-compact Marx-type high-voltage generator

DOEpatents

Goerz, David A.; Wilson, Michael J.

2000-01-01

An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

Development of a strontium optical lattice clock for space applications

NASA Astrophysics Data System (ADS)

Singh, Yeshpal

2016-07-01

With timekeeping being of paramount importance for modern life, much research and major scientific advances have been undertaken in the field of frequency metrology, particularly over the last few years. New Nobel-prize winning technologies have enabled a new era of atomic clocks; namely the optical clock. These have been shown to perform significantly better than the best microwave clocks reaching an inaccuracy of 1.6x10-18 [1]. With such results being found in large lab based apparatus, the focus now has shifted to portability - to enable the accuracy of various ground based clocks to be measured, and compact autonomous performance - to enable such technologies to be tested in space. This could lead to a master clock in space, improving not only the accuracy of technologies on which modern life has come to require such as GPS and communication networks. But also more fundamentally, this could lead to the redefinition of the second and tests of fundamental physics including applications in the fields of ground based and satellite geodesy, metrology, positioning, navigation, transport and logistics etc. Within the European collaboration, Space Optical Clocks (SOC2) [2-3] consisting of various institutes and industry partners across Europe we have tried to tackle this problem of miniaturisation whilst maintaining stability, accuracy (5x10-17) and robustness whilst keeping power consumption to a minimum - necessary for space applications. We will present the most recent results of the Sr optical clock in SOC2 and also the novel compact design features, new methods employed and outlook. References [1] B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, "An optical lattice clock with accuracy and stability at the 10-18 level," Nature 506, 71-75 (2014). [2] S. Schiller et al. "Towards Neutral-atom Space Optical Clocks (SOC2): Development of high-performance transportable and breadboard optical clocks and advanced subsystems" on "Let's embrace space, volume II" 45, 452-463 (2012). ISBN 978-92-79-22207-8. [3] www.soc2.eu

The Evolution of Compact Binary Star Systems.

PubMed

Postnov, Konstantin A; Yungelson, Lev R

2006-01-01

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars - compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.

A high order compact least-squares reconstructed discontinuous Galerkin method for the steady-state compressible flows on hybrid grids

NASA Astrophysics Data System (ADS)

Cheng, Jian; Zhang, Fan; Liu, Tiegang

2018-06-01

In this paper, a class of new high order reconstructed DG (rDG) methods based on the compact least-squares (CLS) reconstruction [23,24] is developed for simulating the two dimensional steady-state compressible flows on hybrid grids. The proposed method combines the advantages of the DG discretization with the flexibility of the compact least-squares reconstruction, which exhibits its superior potential in enhancing the level of accuracy and reducing the computational cost compared to the underlying DG methods with respect to the same number of degrees of freedom. To be specific, a third-order compact least-squares rDG(p1p2) method and a fourth-order compact least-squares rDG(p2p3) method are developed and investigated in this work. In this compact least-squares rDG method, the low order degrees of freedom are evolved through the underlying DG(p1) method and DG(p2) method, respectively, while the high order degrees of freedom are reconstructed through the compact least-squares reconstruction, in which the constitutive relations are built by requiring the reconstructed polynomial and its spatial derivatives on the target cell to conserve the cell averages and the corresponding spatial derivatives on the face-neighboring cells. The large sparse linear system resulted by the compact least-squares reconstruction can be solved relatively efficient when it is coupled with the temporal discretization in the steady-state simulations. A number of test cases are presented to assess the performance of the high order compact least-squares rDG methods, which demonstrates their potential to be an alternative approach for the high order numerical simulations of steady-state compressible flows.

Representations of the Bondi—Metzner—Sachs group in three space—time dimensions

NASA Astrophysics Data System (ADS)

Melas, Evangelos

2017-01-01

The original Bondi-Metzner-Sachs group B is the common asymptotic symmetry group of all asymptotically at Lorentzian 4-dim space-times. As such, B is the best candidate for the universal symmetry group of General Relativity (G.R.). In 1973, with this motivation, P. J. McCarthy classified all relativistic B-invariant systems in terms of strongly continuous irreducible unitary representations (IRS) of B. Here, we construct the IRS of B(2, 1), the analogue of B, in 3 space-time dimensions. The IRS are induced from ‘little groups’ which are compact. The finite ‘little groups’ are cyclic groups of even order. The inducing construction is exhaustive notwithstanding the fact that B(2, 1) is not locally compact in the employed Hilbert topology.

Coherent States for Kronecker Products of Non Compact Groups: Formulation and Applications

NASA Technical Reports Server (NTRS)

Bambah, Bindu A.; Agarwal, Girish S.

1996-01-01

We introduce and study the properties of a class of coherent states for the group SU(1,1) X SU(1,1) and derive explicit expressions for these using the Clebsch-Gordan algebra for the SU(1,1) group. We restrict ourselves to the discrete series representations of SU(1,1). These are the generalization of the 'Barut Girardello' coherent states to the Kronecker Product of two non-compact groups. The resolution of the identity and the analytic phase space representation of these states is presented. This phase space representation is based on the basis of products of 'pair coherent states' rather than the standard number state canonical basis. We discuss the utility of the resulting 'bi-pair coherent states' in the context of four-mode interactions in quantum optics.

High strength-high conductivity Cu--Fe composites produced by powder compaction/mechanical reduction

DOEpatents

Verhoeven, John D.; Spitzig, William A.; Gibson, Edwin D.; Anderson, Iver E.

1991-08-27

A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an "in-situ" Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite.

Dynamics modelling and Hybrid Suppression Control of space robots performing cooperative object manipulation

NASA Astrophysics Data System (ADS)

Zarafshan, P.; Moosavian, S. Ali A.

2013-10-01

Dynamics modelling and control of multi-body space robotic systems composed of rigid and flexible elements is elaborated here. Control of such systems is highly complicated due to severe under-actuated condition caused by flexible elements, and an inherent uneven nonlinear dynamics. Therefore, developing a compact dynamics model with the requirement of limited computations is extremely useful for controller design, also to develop simulation studies in support of design improvement, and finally for practical implementations. In this paper, the Rigid-Flexible Interactive dynamics Modelling (RFIM) approach is introduced as a combination of Lagrange and Newton-Euler methods, in which the motion equations of rigid and flexible members are separately developed in an explicit closed form. These equations are then assembled and solved simultaneously at each time step by considering the mutual interaction and constraint forces. The proposed approach yields a compact model rather than common accumulation approach that leads to a massive set of equations in which the dynamics of flexible elements is united with the dynamics equations of rigid members. To reveal such merits of this new approach, a Hybrid Suppression Control (HSC) for a cooperative object manipulation task will be proposed, and applied to usual space systems. A Wheeled Mobile Robotic (WMR) system with flexible appendages as a typical space rover is considered which contains a rigid main body equipped with two manipulating arms and two flexible solar panels, and next a Space Free Flying Robotic system (SFFR) with flexible members is studied. Modelling verification of these complicated systems is vigorously performed using ANSYS and ADAMS programs, while the limited computations of RFIM approach provides an efficient tool for the proposed controller design. Furthermore, it will be shown that the vibrations of the flexible solar panels results in disturbing forces on the base which may produce undesirable errors and perturb the object manipulation task. So, it is shown that these effects can be significantly eliminated by the proposed Hybrid Suppression Control algorithm.

Method for shearing spent nuclear fuel assemblies

DOEpatents

Weil, Bradley S.; Watson, Clyde D.

1977-01-01

A method is disclosed for shearing spent nuclear fuel assemblies of the type wherein a plurality of long metal tubes packed with ceramic fuel are supported in a spaced apart relationship within an outer metal shell or shroud which provides structural support to the assembly. Spent nuclear fuel assemblies are first compacted in a stepwise manner between specially designed gag-compactors and then sheared into short segments amenable to chemical processing by shear blades contoured to mate with the compacted surface of the fuel assembly.

The Reusable Handheld Electrolyte and Lab Technology for Humans (rHEALTH) Sensor

NASA Technical Reports Server (NTRS)

Chan, Eugene

2015-01-01

The DNA Medicine Institute has produced a reusable microfluidic device that performs rapid, low-cost cell counts and measurements of electrolytes, proteins, and other biomarkers. The rHEALTH sensor is compact and portable, and it employs cutting-edge fluorescence detection optics, innovative microfluidics, and nanostrip reagents to perform a suite of hematology, chemistry, and biomarker assays from a single drop of blood. A handful of current portable POC devices provide generalized blood analysis, but they perform only a few tests at a time. These devices also rely on disposable components and depend on diverse detection technologies to complete routine tests-all ill-suited for space travelers on extended missions. In contrast, the rHEALTH sensor integrates sample introduction, processing, and detection with a compact, resource-conscious, and efficient design. Developed to monitor astronaut health on the International Space Station and during long-term space flight, this microscale lab analysis tool also has terrestrial applications that include POC diagnostics conducted at a patient's bedside, in a doctor's office, and in a hospital.

A geometrical upper bound on the inflaton range

NASA Astrophysics Data System (ADS)

Cicoli, Michele; Ciupke, David; Mayrhofer, Christoph; Shukla, Pramod

2018-05-01

We argue that in type IIB LVS string models, after including the leading order moduli stabilisation effects, the moduli space for the remaining flat directions is compact due the Calabi-Yau Kähler cone conditions. In cosmological applications, this gives an inflaton field range which is bounded from above, in analogy with recent results from the weak gravity and swampland conjectures. We support our claim by explicitly showing that it holds for all LVS vacua with h 1,1 = 3 obtained from 4-dimensional reflexive polytopes. In particular, we first search for all Calabi-Yau threefolds from the Kreuzer-Skarke list with h 1,1 = 2, 3 and 4 which allow for LVS vacua, finding several new LVS geometries which were so far unknown. We then focus on the h 1,1 = 3 cases and show that the Kähler cones of all toric hypersurface threefolds force the effective 1-dimensional LVS moduli space to be compact. We find that the moduli space size can generically be trans-Planckian only for K3 fibred examples.

Method of making a catalytic reactor for automobile

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

Vroman, W.R.

1976-09-07

A catalytic reactor is made by providing a generally cylindrical catalytic substrate of oval transverse section and clamping the same between paired housing shells to form a housing of oval section spaced from the substrate by means of a pair of wire mesh ropes seated within a corresponding pair of grooves extending around the periphery of the substrate at axially spaced locations. Each rope is compacted from a matrix of multiple layers of resilient stainless steel knitted wire and is interlocked with the housing by means of a pair of inwardly opening channels of the housing spaced axially by anmore » inwardly projecting rib of the housing. The grooves in the substrate are pressed radially into the latter while the same is in a plastic uncured condition, thereby to compact and reinforce the grooves to withstand the localized compressional force of the ropes seated therein after the substrate is cured and hardened and clamped between the housing shells.« less

Minimal measures for Euler-Lagrange flows on finite covering spaces

NASA Astrophysics Data System (ADS)

Wang, Fang; Xia, Zhihong

2016-12-01

In this paper we study the minimal measures for positive definite Lagrangian systems on compact manifolds. We are particularly interested in manifolds with more complicated fundamental groups. Mather’s theory classifies the minimal or action-minimizing measures according to the first (co-)homology group of a given manifold. We extend Mather’s notion of minimal measures to a larger class for compact manifolds with non-commutative fundamental groups, and use finite coverings to study the structure of these extended minimal measures. We also define action-minimizers and minimal measures in the homotopical sense. Our program is to study the structure of homotopical minimal measures by considering Mather’s minimal measures on finite covering spaces. Our goal is to show that, in general, manifolds with a non-commutative fundamental group have a richer set of minimal measures, hence a richer dynamical structure. As an example, we study the geodesic flow on surfaces of higher genus. Indeed, by going to the finite covering spaces, the set of minimal measures is much larger and more interesting.

Multivalent Lipid--DNA Complexes: Distinct DNA Compaction Regimes

NASA Astrophysics Data System (ADS)

Evans, Heather M.; Ahmad, A.; Ewert, K.; Safinya, C. R.

2004-03-01

Cationic liposomes (CL), while intrinsically advantageous in comparison to viruses, still have limited success for gene therapy and require more study. CL spontaneously self-assemble with DNA via counterion release, forming small particles approximately 200nm in diameter. X-ray diffraction reveals CL-DNA structures that are typically a multilamellar organization of lipids with DNA intercalated between the layers. We explore the structural properties of CL-DNA complexes formed with new multivalent lipids (Ewert et al, J. Med. Chem. 2002; 45:5023) that range from 2+ to 16+. Contrary to a simple prediction for the DNA interaxial spacing d_DNA based on a geometrical space-filling model, these lipids show dramatic DNA compaction, down to d_DNA ˜ 25 ÅVariations in the membrane charge density, σ _M, lead to distinct spacing regimes. We propose that this DNA condensation is controlled by a unique locking mechanism between the DNA double helix and the large, multivalent lipid head groups. Funded by NSF DMR-0203755 and NIH GM-59288.

Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2016-01-01

This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

Development of a Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN)

NASA Technical Reports Server (NTRS)

Doggett, William R.; Dorsey, John T.; Jones, Thomas C.; King, Bruce

2014-01-01

An invention of a new and novel space robotic manipulator is described. By using a combination of lightweight truss links, a novel hinge joint, tendon-articulation and passive tension stiffening, this new robotic manipulator architecture achieves compact packaging, high strength, stiffness and dexterity while being very lightweight compared to conventional manipulators. The manipulator is also very modular; easy to scale for different reach, load and stiffness requirements; enabling customization for a diverse set of applications. Novel features of the new manipulator concept are described as well as some of the approaches to implement these design features. Two diverse applications are presented to show the versatility of the concept. First generation prototype hardware was designed, manufactured and has been assembled into a working manipulator that is being used to refine and extend development efforts.

A flange on electron spectromicroscope with spherical deflector analyzer--simultaneous imaging of reciprocal and real spaces.

PubMed

Grzelakowski, Krzysztof P

2013-07-01

An instrumental realization of the idea for the electron emission spectromicroscope based on the newly developed imaging energy filter called α-SDA (Spherical Deflector Analyzer) is reported. Its compact design enables the realization of the flange-on spectromicroscope concept. It is equipped with two independent energy selective imaging channels: one for real and another for reciprocal space visualization. These images can be acquired quasi-simultaneousely by means of the software based on the switching on and off potentials of the energy filter. An electron gun located inside the immersion objective lens allows a new kind of sample illumination by high energy primary electrons and thus, opens a new application field for electron spectromicroscopy under laboratory conditions. Copyright © 2013 Elsevier B.V. All rights reserved.

Lightweight Modular Instrumentation for Planetary Applications

NASA Technical Reports Server (NTRS)

Joshi, P. B.

1993-01-01

An instrumentation, called Space Active Modular Materials ExperimentS (SAMMES), is developed for monitoring the spacecraft environment and for accurately measuring the degradation of space materials in low earth orbit (LEO). The SAMMES architecture concept can be extended to instrumentation for planetary exploration, both on spacecraft and in situ. The operating environment for planetary application will be substantially different, with temperature extremes and harsh solar wind and cosmic ray flux on lunar surfaces and temperature extremes and high winds on venusian and Martian surfaces. Moreover, instruments for surface deployment, which will be packaged in a small lander/rover (as in MESUR, for example), must be extremely compact with ultralow power and weight. With these requirements in mind, the SAMMES concept was extended to a sensor/instrumentation scheme for the lunar and Martian surface environment.

Phase-locked, erbium-fiber-laser-based frequency comb in the near infrared.

PubMed

Washburn, Brian R; Diddams, Scott A; Newbury, Nathan R; Nicholson, Jeffrey W; Yan, Man F; Jørgensen, Carsten G

2004-02-01

A phase-locked frequency comb in the near infrared is demonstrated with a mode-locked, erbium-doped, fiber laser whose output is amplified and spectrally broadened in dispersion-flattened, highly nonlinear optical fiber to span from 1100 to >2200 nm. The supercontinuum output comprises a frequency comb with a spacing set by the laser repetition rate and an offset by the carrier-envelope offset frequency, which is detected with the standard f-to-2f heterodyne technique. The comb spacing and offset frequency are phase locked to a stable rf signal with a fiber stretcher in the laser cavity and by control of the pump laser power, respectively. This infrared comb permits frequency metrology experiments in the near infrared in a compact, fiber-laser-based system.

A spatial dynamic model to assess piospheric land degradation processes of SW Iberian rangelands

NASA Astrophysics Data System (ADS)

Herguido Sevillano, Estela; Ibáñez, Javier; Francisco Lavado Contador, Joaquín; Pulido-Fernández, Manuel; Schnabel, Susanne

2015-04-01

Iberian open wooded rangelands (known as dehesas or montados) constitute valuable agro-silvo-pastoral systems traditionally considered as highly sustainable. Nevertheless, in the recent decades, those systems are undergoing changes of land use and management practices that compromise its sustainability. Some of those changes, as the rising construction of watering points and the high spatial fragmentation and livestock movement restriction associated to fencing, show an aggregated effect with livestock, producing an impact gradient over soil and vegetation. Soil compaction related to livestock pressure is higher around watering points, with bare soil halos and patches of scarce vegetation or nude soil developing with higher frequency in areas close to them. Using the freeware Dinamica EGO as environmental modeling platform, we have developed a theoretic spatial dynamic model that represents some of the processes of land degradation associated to livestock grazing in dehesa fenced enclosures. Spatial resolution is high since every cell in the model is a square unit area of 1 m2. We paid particular attention to the relationships between soil degradation by compaction (porosity), livestock pressure, rainfall, pasture growth and shrub cover and bare soil generation. The model considers pasture growth as related to soil compaction, measured by the pore space in the top 10 cm soil layer. Annual precipitation is randomly generated following a normal distribution. When annual precipitation and pore space increase, also does pasture growth. Besides, there is a feedback between pasture growth and pore space, given that pasture roots increases soil porosity. The cell utility for livestock function has been defined as an exponential function of the distance of a cell to watering points and the amount of pasture present in it. The closer the cell to a pond and the higher the amount of pasture, the higher is cell utility. The latter is modulated by a normal random variable to capture accidental effects. This variable has zero mean and a standard deviation linearly related to the distance to the pond. Livestock utilization of a cell is a function of its relative utility, the stocking rate and the time that animals spend at the enclosure. Since livestock trampling promotes soil compaction, livestock utilization has a negative effect on pore space. The probability of transition from herbaceous to shrubs is also modulated by pore space, and thus livestock utilization, as shrub development needs a minimum porosity value for seeds to successfully germinate. In addition, it is influenced by the proportion of cells occupied by shrubs in a radius where seed dispersal or exclusion by competition may occur. The model contemplates the probability of transition from shrubs to herbaceous through shrub mortality, and the age of the shrubs, which influences seed production and shrub cover. Pasture consumption by livestock and pasture remaining at the end of summer were also modeled, so that it is possible to obtain maps of bare soil at that time. Likewise, the model generates maps of vegetation state (shrubs or herbaceous) and pasture growth. The values of the set of 31 parameters were obtained from field measurements and from publications. Those parameters lacking quantitative information were calibrated by comparing model performance with the dynamics of true enclosures analyzed between 1984 and 2009 in ortophotographs. Stocking rates were inferred from farmers' interviews performed in 2009 about present and past land use and management practices. The model developed is intended to analyze strategies of livestock management in dehesas. Particularly, soil conservation practices as related to livestock pressure can be simulated looking for optimized schemes. Moreover, the model provides the possibility of generating simulations for future climate scenarios, studying the effects of climate change on livestock carrying capacity on these systems. Thanks to the Spanish Ministerio de Economía y Competitividad for financially supporting this study through AMID (CGL2011-23361) project.

Space Technology: Game Changing Development Deep Space Engine (DSE) 100 lbf and 5 lbf Thruster Development and Qualification

NASA Technical Reports Server (NTRS)

Barnett, Gregory

2017-01-01

Science mission studies require spacecraft propulsion systems that are high-performance, lightweight, and compact. Highly matured technology and low-cost, short development time of the propulsion system are also very desirable. The Deep Space Engine (DSE) 100-lbf thruster is being developed to meet these needs. The overall goal of this game changing technology project is to qualify the DSE thrusters along with 5-lbf attitude control thrusters for space flight and for inclusion in science and exploration missions. The aim is to perform qualification tests representative of mission duty cycles. Most exploration missions are constrained by mass, power and cost. As major propulsion components, thrusters are identified as high-risk, long-lead development items. NASA spacecraft primarily rely on 1960s' heritage in-space thruster designs and opportunities exist for reducing size, weight, power, and cost through the utilization of modern materials and advanced manufacturing techniques. Advancements in MON-25/MMH hypergolic bipropellant thrusters represent a promising avenue for addressing these deficiencies with tremendous mission enhancing benefits. DSE is much lighter and costs less than currently available thrusters in comparable thrust classes. Because MON-25 propellants operate at lower temperatures, less power is needed for propellant conditioning for in-space propulsion applications, especially long duration and/or deep-space missions. Reduced power results in reduced mass for batteries and solar panels. DSE is capable of operating at a wide propellant temperature range (between -22 F and 122 F) while a similar existing thruster operates between 45 F and 70 F. Such a capability offers robust propulsion operation as well as flexibility in design. NASA's Marshall Space Flight Center evaluated available operational Missile Defense Agency heritage thrusters suitable for the science and lunar lander propulsion systems.

Space-time development of electromagnetic and hadronic showers and perspectives for novel calorimetric techniques

DOE PAGES

Benaglia, Andrea; Auffray, Etiennette; Lecoq, Paul; ...

2016-04-20

The performance of hadronic calorimeters will be a key parameter at the next generation of High Energy Physics accelerators. A detector combining fine granularity with excellent timing information would prove beneficial for the reconstruction of both jets and electromagnetic particles with high energy resolution. In this work, the space and time structure of high energy showers is studied by means of a Geant4-based simulation toolkit. In particular, the relevant time scales of the different physics phenomena contributing to the energy loss are investigated. A correlation between the fluctuations of the energy deposition of high energy hadrons and the time developmentmore » of the showers is observed, which allows for an event-by-event correction to be computed to improve the energy resolution of the calorimeter. Lastly, these studies are intended to set the basic requirements for the development of a new-concept, total absorption time-imaging calorimeter, which seems now within reach thanks to major technological advancements in the production of fast scintillating materials and compact photodetectors.« less

Adaptive multiconfigurational wave functions

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

Evangelista, Francesco A., E-mail: francesco.evangelista@emory.edu

2014-03-28

A method is suggested to build simple multiconfigurational wave functions specified uniquely by an energy cutoff Λ. These are constructed from a model space containing determinants with energy relative to that of the most stable determinant no greater than Λ. The resulting Λ-CI wave function is adaptive, being able to represent both single-reference and multireference electronic states. We also consider a more compact wave function parameterization (Λ+SD-CI), which is based on a small Λ-CI reference and adds a selection of all the singly and doubly excited determinants generated from it. We report two heuristic algorithms to build Λ-CI wave functions.more » The first is based on an approximate prescreening of the full configuration interaction space, while the second performs a breadth-first search coupled with pruning. The Λ-CI and Λ+SD-CI approaches are used to compute the dissociation curve of N{sub 2} and the potential energy curves for the first three singlet states of C{sub 2}. Special attention is paid to the issue of energy discontinuities caused by changes in the size of the Λ-CI wave function along the potential energy curve. This problem is shown to be solvable by smoothing the matrix elements of the Hamiltonian. Our last example, involving the Cu{sub 2}O{sub 2}{sup 2+} core, illustrates an alternative use of the Λ-CI method: as a tool to both estimate the multireference character of a wave function and to create a compact model space to be used in subsequent high-level multireference coupled cluster computations.« less

Advanced Development of a Compact 5-15 lbf Lox/Methane Thruster for an Integrated Reaction Control and Main Engine Propulsion System

NASA Technical Reports Server (NTRS)

Hurlbert, Eric A.; McManamen, John Patrick; Sooknanen, Josh; Studak, Joseph W.

2011-01-01

This paper describes the advanced development and testing of a compact 5 to 15 lbf LOX/LCH4 thruster for a pressure-fed integrated main engine and RCS propulsion system to be used on a spacecraft "vertical" test bed (VTB). The ability of the RCS thruster and the main engine to operate off the same propellant supply in zero-g reduces mass and improves mission flexibility. This compact RCS engine incorporates several features to dramatically reduce mass and parts count, to ease manufacturing, and to maintain acceptable performance given that specific impulse (Isp) is not the driver. For example, radial injection holes placed on the chamber body for easier drilling, and high temperature Haynes 230 were selected for the chamber over other more expensive options. The valve inlets are rotatable before welding allowing different orientations for vehicle integration. In addition, the engine design effort selected a coil-on-plug ignition system which integrates a relay and coil with the plug electrode, and moves some exciter electronics to avionics driver board. The engine injector design has small dribble volumes to target minimum pulse widths of 20 msec. and an efficient minimum impulse bit of less than 0.05 lbf-sec. The propellants, oxygen and methane, were chosen because together they are a non-toxic, Mars-forward, high density, space storable, and high performance propellant combination that is capable of pressure-fed and pump-fed configurations and integration with life support and power subsystems. This paper will present the results of the advanced development testing to date of the RCS thruster and the integration with a vehicle propulsion system.

A Stirling Idea

NASA Technical Reports Server (NTRS)

1998-01-01

Stirling Technology Company developed the components for its BeCOOL line of Cryocoolers with the help of a series of NASA SBIRs (Small Business Innovative Research), through Goddard Space Flight Center and Marshall Space Flight Center. Features include a hermetically sealed design, compact size, and silent operation. The company has already placed several units with commercial customers for computer applications and laboratory use.

High-energy astrophysics and the search for sources of gravitational waves

NASA Astrophysics Data System (ADS)

O'Brien, P. T.; Evans, P.

2018-05-01

The dawn of the gravitational-wave (GW) era has sparked a greatly renewed interest into possible links between sources of high-energy radiation and GWs. The most luminous high-energy sources-gamma-ray bursts (GRBs)-have long been considered as very likely sources of GWs, particularly from short-duration GRBs, which are thought to originate from the merger of two compact objects such as binary neutron stars and a neutron star-black hole binary. In this paper, we discuss: (i) the high-energy emission from short-duration GRBs; (ii) what other sources of high-energy radiation may be observed from binary mergers; and (iii) how searches for high-energy electromagnetic counterparts to GW events are performed with current space facilities. While current high-energy facilities, such as Swift and Fermi, play a crucial role in the search for electromagnetic counterparts, new space missions will greatly enhance our capabilities for joint observations. We discuss why such facilities, which incorporate new technology that enables very wide-field X-ray imaging, are required if we are to truly exploit the multi-messenger era. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

High-energy astrophysics and the search for sources of gravitational waves.

PubMed

O'Brien, P T; Evans, P

2018-05-28

The dawn of the gravitational-wave (GW) era has sparked a greatly renewed interest into possible links between sources of high-energy radiation and GWs. The most luminous high-energy sources-gamma-ray bursts (GRBs)-have long been considered as very likely sources of GWs, particularly from short-duration GRBs, which are thought to originate from the merger of two compact objects such as binary neutron stars and a neutron star-black hole binary. In this paper, we discuss: (i) the high-energy emission from short-duration GRBs; (ii) what other sources of high-energy radiation may be observed from binary mergers; and (iii) how searches for high-energy electromagnetic counterparts to GW events are performed with current space facilities. While current high-energy facilities, such as Swift and Fermi, play a crucial role in the search for electromagnetic counterparts, new space missions will greatly enhance our capabilities for joint observations. We discuss why such facilities, which incorporate new technology that enables very wide-field X-ray imaging, are required if we are to truly exploit the multi-messenger era.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'. © 2018 The Author(s).

First results from the faint object camera - High-resolution observations of the central object R136 in the 30 Doradus nebula

NASA Technical Reports Server (NTRS)

Weigelt, G.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

1991-01-01

R136 is the luminous central object of the giant H II region 30 Doradus in the LMC. The first high-resolution observations of R136 with the Faint Object Camera on board the Hubble Space Telescope are reported. The physical nature of the brightest component R136a has been a matter of some controversy over the last few years. The UV images obtained show that R136a is a very compact star cluster consisting of more than eight stars within 0.7 arcsec diameter. From these high-resolution images a mass upper limit can be derived for the most luminous stars observed in R136.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

DOE PAGES

Liu, Bo; Braiman, Yehuda

2018-02-06

In this paper, we introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ~25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. Finally, we found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

NASA Astrophysics Data System (ADS)

Liu, Bo; Braiman, Yehuda

2018-05-01

We introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ∼25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. We found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

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

Liu, Bo; Braiman, Yehuda

In this paper, we introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ~25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. Finally, we found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Nuclear fuel particles and method of making nuclear fuel compacts therefrom

DOEpatents

DeVelasco, Rubin I.; Adams, Charles C.

1991-01-01

Methods for making nuclear fuel compacts exhibiting low heavy metal contamination and fewer defective coatings following compact fabrication from a mixture of hardenable binder, such as petroleum pitch, and nuclear fuel particles having multiple layer fission-product-retentive coatings, with the dense outermost layer of the fission-product-retentive coating being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.3 g/cm.sup.3. Such particles can be pre-compacted in molds under relatively high pressures and then combined with a fluid binder which is ultimately carbonized to produce carbonaceous nuclear fuel compacts having relatively high fuel loadings.

Earth in Space: A CD-ROM Version for Pre-College Teachers

NASA Astrophysics Data System (ADS)

Pedigo, P.

2003-12-01

Earth in Space, a magazine about the Earth and space sciences for pre-college science teachers, was published by AGU between 1987 and 2001 (9 issues each year). The goal of Earth in Space was to make research at the frontiers of the geosciences accessible to teachers and students and engage them in thinking about scientific careers. Each issue contained two or three recent research articles, rewritten for a high school level audience from the original version published in peer-reviewed AGU journals, which were supplemented with short news items and biographic information about the authors. As part of a 2003 summer internship with AGU, sponsored by the AGU Committee on Education and Human Resources (CEHR) and the American Institute of Physics, this collection of Earth in Space magazines was converted into an easily accessible electronic resource for K-12 teachers and students. Every issue was scanned into a PDF file. The entire collection of articles was cataloged in a database indexed to key topic terms (e.g., volcanoes, global climate change, space weather). A front-page was designed in order to facilitate rapid access to articles concerning specific topics within the Earth and space sciences of particular interest to high school students. A compact CD-ROM version of this resource will be distributed to science teachers at future meetings of the National Science Teachers Association and will be made available through AGU's Outreach and Research Support program.

Soil compaction: Evaluation of stress transmission and resulting soil structure

NASA Astrophysics Data System (ADS)

Naveed, Muhammad; Schjønning, Per; Keller, Thomas; Lamande, Mathieu

2016-04-01

Accurate estimation of stress transmission and resultant deformation in soil profiles is a prerequisite for the development of predictive models and decision support tools for preventing soil compaction. Numerous studies have been carried out on the effects of soil compaction, whilst relatively few studies have focused on the cause (mode of stress transmission in the soil). We have coupled both cause and effects together in the present study by carrying out partially confined compression tests on (1) wet aggregates, (2) air dry aggregates, and (3) intact soils to quantify stress transmission and compaction-resulted soil structure at the same time. Stress transmission was quantified using both X-ray CT and Tactilus sensor mat, and soil-pore structure was quantified using X-ray CT. Our results imply that stress transmission through soil highly depends on the magnitude of applied load and aggregate strength. As soon as the applied load is lower than the aggregate strength, the mode of stress transmission is discrete as stresses were mainly transmitted through chain of aggregates. With increasing applied load soil aggregates start deforming that transformed heterogeneous soil into homogenous, as a result stress transmission mode was shifted from discrete towards more like a continuum. Continuum-like stress transmission mode was better simulated with Boussinesq (1885) model based on theory of elasticity compared to discrete. The soil-pore structure was greatly affected by increasing applied stresses. Total porosity was reduced 5-16% and macroporosity 50-85% at 620 kPa applied stress for the intact soils. Similarly, significant changes in the morphological indices of the macropore space were also observed with increasing applied stresses.

High strength-high conductivity Cu-Fe composites produced by powder compaction/mechanical reduction

DOEpatents

Verhoeven, J.D.; Spitzig, W.A.; Gibson, E.D.; Anderson, I.E.

1991-08-27

A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an ''in-situ'' Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite. 5 figures.

Characterization of the reference wave in a compact digital holographic camera.

PubMed

Park, I S; Middleton, R J C; Coggrave, C R; Ruiz, P D; Coupland, J M

2018-01-01

A hologram is a recording of the interference between an unknown object wave and a coherent reference wave. Providing the object and reference waves are sufficiently separated in some region of space and the reference beam is known, a high-fidelity reconstruction of the object wave is possible. In traditional optical holography, high-quality reconstruction is achieved by careful reillumination of the holographic plate with the exact same reference wave that was used at the recording stage. To reconstruct high-quality digital holograms the exact parameters of the reference wave must be known mathematically. This paper discusses a technique that obtains the mathematical parameters that characterize a strongly divergent reference wave that originates from a fiber source in a new compact digital holographic camera. This is a lensless design that is similar in principle to a Fourier hologram, but because of the large numerical aperture, the usual paraxial approximations cannot be applied and the Fourier relationship is inexact. To characterize the reference wave, recordings of quasi-planar object waves are made at various angles of incidence using a Dammann grating. An optimization process is then used to find the reference wave that reconstructs a stigmatic image of the object wave regardless of the angle of incidence.

Design and expected performance of a compact and continuous nuclear demagnetization refrigerator for sub-mK applications

NASA Astrophysics Data System (ADS)

Toda, Ryo; Murakawa, Satoshi; Fukuyama, Hiroshi

2018-03-01

Sub-mK temperatures are achievable by a copper nuclear demagnetization refrigerator (NDR). Recently, research demands for such an ultra-low temperature environment are increasing not only in condensed matter physics but also in astrophysics. A standard NDR requires a specially designed room, a high-field superconducting magnet, and a high-power dilution refrigerator (DR). And it is a one-shot cooling apparatus. To reduce these requirements, we are developing a compact and continuous NDR with two PrNi5 nuclear stages which occupies only a small space next to an appropriate pre-cooling stage such as DR. PrNi5 has a large magnetic-field enhancement on Pr3+ nuclei due to the strong hyperfine coupling. This enables us to enclose each stage in a miniature superconducting magnet and to locate two such sets in close proximity by surrounding them with high-permeability magnetic shields. The two stages are thermally connected in series to the pre-cooling stage by two Zn superconducting heat switches. A numerical analysis taking account of thermal resistances of all parts and an eddy current heating shows that the lowest sample temperature of 0.8 mK can be maintained continuously under a 10 nW ambient heat leak.

MCNP Simulations of Measurement of Insulation Compaction in the Cryogenic Rocket Fuel Tanks at Kennedy Space Center by Fast/Thermal Neutron Techniques

NASA Technical Reports Server (NTRS)

Livingston, R. A.; Schweitzer, J. S.; Parsons, A. M.; Arens, E. E.

2010-01-01

MCNP simulations have been run to evaluate the feasibility of using a combination of fast and thermal neutrons as a nondestructive method to measure of the compaction of the perlite insulation in the liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC). Perlite is a feldspathic volcanic rock made up of the major elements Si, AI, Na, K and 0 along with some water. When heated it expands from four to twenty times its original volume which makes it very useful for thermal insulation. The cryogenic tanks at Kennedy Space Center are spherical with outer diameters of 69-70 feet and lined with a layer of expanded perlite with thicknesses on the order of 120 cm. There is evidence that some of the perlite has compacted over time since the tanks were built 1965, affecting the thermal properties and possibly also the structural integrity of the tanks. With commercially available portable neutron generators it is possible to produce simultaneously fluxes of neutrons in two energy ranges: fast (14 Me V) and thermal (25 me V). The two energy ranges produce complementary information. Fast neutrons produce gamma rays by inelastic scattering, which is sensitive to Fe and O. Thermal neutrons produce gamma rays by prompt gamma neutron activation (PGNA) and this is sensitive to Si, Al, Na, K and H. The compaction of the perlite can be measured by the change in gamma ray signal strength which is proportional to the atomic number densities of the constituent elements. The MCNP simulations were made to determine the magnitude of this change. The tank wall was approximated by a I-dimensional slab geometry with an 11/16" outer carbon steel wall, an inner stainless wall and 120 cm thick perlite zone. Runs were made for cases with expanded perlite, compacted perlite or with various void fractions. Runs were also made to simulate the effect of adding a moderator. Tallies were made for decay-time analysis from t=0 to 10 ms; total detected gamma-rays; detected gamma-rays from thermal neutron reactions d. detected gamma-rays from non-thermal neutron reactions and total detected gamma-rays as a function of depth into the annulus volume. These indicated a number of possible independent metrics of perlite compaction. For example the count rate for perlite elements increased from 3600 to 8500 cps for an increase in perlite density from 6 lbs/lcf to 16.5 lbs/cf. Thus the MCNP simulations have confirmed the feasibility of using neutron methods to map the compaction of perlite in the walls of the cryogenic tanks.

Spectrally Tailored Pulsed Thulium Fiber Laser System for Broadband Lidar CO2 Sensing

NASA Technical Reports Server (NTRS)

Heaps, William S.; Georgieva, Elena M.; McComb, Timothy S.; Cheung, Eric C.; Hassell, Frank R.; Baldauf, Brian K.

2011-01-01

Thulium doped pulsed fiber lasers are capable of meeting the spectral, temporal, efficiency, size and weight demands of defense and civil applications for pulsed lasers in the eye-safe spectral regime due to inherent mechanical stability, compact "all-fiber" master oscillator power amplifier (MOPA) architectures, high beam quality and efficiency. Thulium fiber's longer operating wavelength allows use of larger fiber cores without compromising beam quality, increasing potential single aperture pulse energies. Applications of these lasers include eye-safe laser ranging, frequency conversion to longer or shorter wavelengths for IR countermeasures and sensing applications with otherwise tough to achieve wavelengths and detection of atmospheric species including CO2 and water vapor. Performance of a portable thulium fiber laser system developed for CO2 sensing via a broadband lidar technique with an etalon based sensor will be discussed. The fielded laser operates with approximately 280 J pulse energy in 90-150ns pulses over a tunable 110nm spectral range and has a uniquely tailored broadband spectral output allowing the sensing of multiple CO2 lines simultaneously, simplifying future potentially space based CO2 sensing instruments by reducing the number and complexity of lasers required to carry out high precision sensing missions. Power scaling and future "all fiber" system configurations for a number of ranging, sensing, countermeasures and other yet to be defined applications by use of flexible spectral and temporal performance master oscillators will be discussed. The compact, low mass, robust, efficient and readily power scalable nature of "all-fiber" thulium lasers makes them ideal candidates for use in future space based sensing applications.

High power pulsed sources based on fiber amplifiers

NASA Astrophysics Data System (ADS)

Canat, Guillaume; Jaouën, Yves; Mollier, Jean-Claude; Bouzinac, Jean-Pierre; Cariou, Jean-Pierre

2017-11-01

Cladding-pumped rare-earth-doped fiber laser technologies are currently among the best sources for high power applications. Theses extremely compact and robust sources appoint them as good candidate for aeronautical and space applications. The double-clad (DC) fiber converts the poor beamquality of high-power large-area pump diodes from the 1st cladding to laser light at another wavelength guided in an active single-mode core. High-power coherent MOPA (Master Oscillator Power Amplifier) sources (several 10W CW or several 100W in pulsed regime) will soon be achieved. Unfortunately it also brings nonlinear effects which quickly impairs output signal distortions. Stimulated Brillouin scattering (SBS) and optical parametric amplification (OPA) have been shown to be strong limitations. Based on amplifier modeling and experiments we discuss the performances of these sources.

Invariant Measures for Dissipative Dynamical Systems: Abstract Results and Applications

NASA Astrophysics Data System (ADS)

Chekroun, Mickaël D.; Glatt-Holtz, Nathan E.

2012-12-01

In this work we study certain invariant measures that can be associated to the time averaged observation of a broad class of dissipative semigroups via the notion of a generalized Banach limit. Consider an arbitrary complete separable metric space X which is acted on by any continuous semigroup { S( t)} t ≥ 0. Suppose that { S( t)} t ≥ 0 possesses a global attractor {{A}}. We show that, for any generalized Banach limit LIM T → ∞ and any probability distribution of initial conditions {{m}_0}, that there exists an invariant probability measure {{m}}, whose support is contained in {{A}}, such that intX \\varphi(x) d{m}(x) = \\underset{t rightarrow infty}LIM1/T int_0^T int_X \\varphi(S(t) x) d{m}_0(x) dt, for all observables φ living in a suitable function space of continuous mappings on X. This work is based on the framework of Foias et al. (Encyclopedia of mathematics and its applications, vol 83. Cambridge University Press, Cambridge, 2001); it generalizes and simplifies the proofs of more recent works (Wang in Disc Cont Dyn Syst 23(1-2):521-540, 2009; Lukaszewicz et al. in J Dyn Diff Eq 23(2):225-250, 2011). In particular our results rely on the novel use of a general but elementary topological observation, valid in any metric space, which concerns the growth of continuous functions in the neighborhood of compact sets. In the case when { S( t)} t ≥ 0 does not possess a compact absorbing set, this lemma allows us to sidestep the use of weak compactness arguments which require the imposition of cumbersome weak continuity conditions and thus restricts the phase space X to the case of a reflexive Banach space. Two examples of concrete dynamical systems where the semigroup is known to be non-compact are examined in detail. We first consider the Navier-Stokes equations with memory in the diffusion terms. This is the so called Jeffery's model which describes certain classes of viscoelastic fluids. We then consider a family of neutral delay differential equations, that is equations with delays in the time derivative terms. These systems may arise in the study of wave propagation problems coming from certain first order hyperbolic partial differential equations; for example for the study of line transmission problems. For the second example the phase space is {X= C([-tau,0],{R}^n)}, for some delay τ > 0, so that X is not reflexive in this case.