Disentangling internal and external factors in bimodal acquisition

NARCIS (Netherlands)

Hulk, A.; Van den Bogaerde, B.

2016-01-01

In this commentary we address some of the internal and external factors which are generally found to interact with purely linguistic factors in the languages of bimodal children, and which we think should be taken into account while analysing the bimodal data.

Influence of age, spatial memory, and ocular fixation on localization of auditory, visual, and bimodal targets by human subjects.

Science.gov (United States)

Dobreva, Marina S; O'Neill, William E; Paige, Gary D

2012-12-01

A common complaint of the elderly is difficulty identifying and localizing auditory and visual sources, particularly in competing background noise. Spatial errors in the elderly may pose challenges and even threats to self and others during everyday activities, such as localizing sounds in a crowded room or driving in traffic. In this study, we investigated the influence of aging, spatial memory, and ocular fixation on the localization of auditory, visual, and combined auditory-visual (bimodal) targets. Head-restrained young and elderly subjects localized targets in a dark, echo-attenuated room using a manual laser pointer. Localization accuracy and precision (repeatability) were quantified for both ongoing and transient (remembered) targets at response delays up to 10 s. Because eye movements bias auditory spatial perception, localization was assessed under target fixation (eyes free, pointer guided by foveal vision) and central fixation (eyes fixed straight ahead, pointer guided by peripheral vision) conditions. Spatial localization across the frontal field in young adults demonstrated (1) horizontal overshoot and vertical undershoot for ongoing auditory targets under target fixation conditions, but near-ideal horizontal localization with central fixation; (2) accurate and precise localization of ongoing visual targets guided by foveal vision under target fixation that degraded when guided by peripheral vision during central fixation; (3) overestimation in horizontal central space (±10°) of remembered auditory, visual, and bimodal targets with increasing response delay. In comparison with young adults, elderly subjects showed (1) worse precision in most paradigms, especially when localizing with peripheral vision under central fixation; (2) greatly impaired vertical localization of auditory and bimodal targets; (3) increased horizontal overshoot in the central field for remembered visual and bimodal targets across response delays; (4) greater vulnerability to

Heatpipe power system and heatpipe bimodal system design and development options

International Nuclear Information System (INIS)

Houts, M.G.; Poston, D.I.; Emrich, W.J. Jr.

1997-01-01

The Heatpipe Power System (HPS) is a potential, near-term, low-cost space fission power system. The Heatpipe Bimodal System (HBS) is a potential, near-term, low-cost space fission power and/or propulsion system. Both systems will be composed of independent modules, and all components operate within the existing databases. The HPS and HBS have relatively few system integration issues; thus, the successful development of a module is a significant step toward verifying system feasibility and performance estimates. A prototypic HPS module is being fabricated, and testing is scheduled to begin in November 1996. A successful test will provide high confidence that the HPS can achieve its predicted performance

Spectra of globular clusters in the Sombrero galaxy: evidence for spectroscopic metallicity bimodality

Science.gov (United States)

Alves-Brito, Alan; Hau, George K. T.; Forbes, Duncan A.; Spitler, Lee R.; Strader, Jay; Brodie, Jean P.; Rhode, Katherine L.

2011-11-01

We present a large sample of over 200 integrated-light spectra of confirmed globular clusters (GCs) associated with the Sombrero (M104) galaxy taken with the Deep Imaging Multi-Object Spectrograph (DEIMOS) instrument on the Keck telescope. A significant fraction of the spectra have signal-to-noise ratio levels high enough to allow measurements of GC metallicities using the method of Brodie & Huchra. We find a distribution of spectroscopic metallicities in the range -2.2 < [Fe/H] < +0.1 that is bimodal, with peaks at [Fe/H]˜-1.4 and -0.6. Thus, the GC system of the Sombrero galaxy, like a few other galaxies now studied in detail, reveals a bimodal spectroscopic metallicity distribution supporting the long-held belief that colour bimodality reflects two metallicity subpopulations. This further suggests that the transformation from optical colour to metallicity for old stellar populations, such as GCs, is not strongly non-linear. We also explore the radial and magnitude distribution with metallicity for GC subpopulations but small number statistics prevent any clear trends in these distributions. Based on observations obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration.

TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, Christopher W.; Nielsen, Nikole M., E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

2012-11-20

We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W{sub r} (2796) {>=} 0.1 A] and 35 spectroscopically confirmed non-absorbing galaxies [W{sub r} (2796) < 0.1 A] imaged with Hubble Space Telescope and Sloan Digital Sky Survey. The azimuthal angle distribution for non-absorbers is flat, indicating no azimuthal preference for gas characterized by W{sub r} (2796) < 0.1 A. We find that blue star-forming galaxies clearly drive the bimodality while red passive galaxies may exhibit an excess along their major axis. These results are consistent with galaxy evolution scenarios where star-forming galaxies accrete new gas, forming new stars and producing winds, while red galaxies exist passively due to reduced gas reservoirs. We further compute an azimuthal angle dependent Mg II absorption covering fraction, which is enhanced by as much as 20%-30% along the major and minor axes. The W{sub r} (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100 Degree-Sign and 40 Degree-Sign , respectively. We find that the probability of detecting outflows is {approx}60%, implying that winds are more commonly observed.

A bimodal biometric identification system

Science.gov (United States)

Laghari, Mohammad S.; Khuwaja, Gulzar A.

2013-03-01

Biometrics consists of methods for uniquely recognizing humans based upon one or more intrinsic physical or behavioral traits. Physicals are related to the shape of the body. Behavioral are related to the behavior of a person. However, biometric authentication systems suffer from imprecision and difficulty in person recognition due to a number of reasons and no single biometrics is expected to effectively satisfy the requirements of all verification and/or identification applications. Bimodal biometric systems are expected to be more reliable due to the presence of two pieces of evidence and also be able to meet the severe performance requirements imposed by various applications. This paper presents a neural network based bimodal biometric identification system by using human face and handwritten signature features.

Advanced Engineering Environments for Space Transportation System Development

Science.gov (United States)

Thomas, L. Dale; Smith, Charles A.; Beveridge, James

2000-01-01

There are significant challenges facing today's launch vehicle industry. Global competition, more complex products, geographically-distributed design teams, demands for lower cost, higher reliability and safer vehicles, and the need to incorporate the latest technologies quicker, all face the developer of a space transportation system. Within NASA, multiple technology development and demonstration projects are underway toward the objectives of safe, reliable, and affordable access to space. New information technologies offer promising opportunities to develop advanced engineering environments to meet these challenges. Significant advances in the state-of-the-art of aerospace engineering practice are envisioned in the areas of engineering design and analytical tools, cost and risk tools, collaborative engineering, and high-fidelity simulations early in the development cycle. At the Marshall Space Flight Center, work has begun on development of an advanced engineering environment specifically to support the design, modeling, and analysis of space transportation systems. This paper will give an overview of the challenges of developing space transportation systems in today's environment and subsequently discuss the advanced engineering environment and its anticipated benefits.

Aggressive Bimodal Communication in Domestic Dogs, Canis familiaris.

Science.gov (United States)

Déaux, Éloïse C; Clarke, Jennifer A; Charrier, Isabelle

2015-01-01

Evidence of animal multimodal signalling is widespread and compelling. Dogs' aggressive vocalisations (growls and barks) have been extensively studied, but without any consideration of the simultaneously produced visual displays. In this study we aimed to categorize dogs' bimodal aggressive signals according to the redundant/non-redundant classification framework. We presented dogs with unimodal (audio or visual) or bimodal (audio-visual) stimuli and measured their gazing and motor behaviours. Responses did not qualitatively differ between the bimodal and two unimodal contexts, indicating that acoustic and visual signals provide redundant information. We could not further classify the signal as 'equivalent' or 'enhancing' as we found evidence for both subcategories. We discuss our findings in relation to the complex signal framework, and propose several hypotheses for this signal's function.

Advanced Solid State Lighting for AES Deep Space Hab

Data.gov (United States)

National Aeronautics and Space Administration — The advanced Solid State Lighting (SSL) assemblies augmented 2nd generation modules under development for the Advanced Exploration Systems Deep Space Habitat in...

Aggressive Bimodal Communication in Domestic Dogs, Canis familiaris.

Directory of Open Access Journals (Sweden)

Éloïse C Déaux

Full Text Available Evidence of animal multimodal signalling is widespread and compelling. Dogs' aggressive vocalisations (growls and barks have been extensively studied, but without any consideration of the simultaneously produced visual displays. In this study we aimed to categorize dogs' bimodal aggressive signals according to the redundant/non-redundant classification framework. We presented dogs with unimodal (audio or visual or bimodal (audio-visual stimuli and measured their gazing and motor behaviours. Responses did not qualitatively differ between the bimodal and two unimodal contexts, indicating that acoustic and visual signals provide redundant information. We could not further classify the signal as 'equivalent' or 'enhancing' as we found evidence for both subcategories. We discuss our findings in relation to the complex signal framework, and propose several hypotheses for this signal's function.

Bimodality and negative heat capacity in multifragmentation

International Nuclear Information System (INIS)

Tamain, B.; Bougault, R.; Lopez, O.; Pichon, M.

2003-01-01

This contribution addresses the question of the possible link between multifragmentation and the liquid-gas phase transition of nuclear matter. Bi-modality seems to be a robust signal of this link in the sense that theoretical calculations indicate that it is preserved even if a sizeable fraction of the available energy has not been shared among all the degrees of freedom. The corresponding measured properties are coherent with what is expected in a liquid-gas phase transition picture. Moreover, bi-modality and negative heat capacity are observed for the same set of events. (authors)

Asymmetric Bimodal Exponential Power Distribution on the Real Line

Directory of Open Access Journals (Sweden)

Mehmet Niyazi Çankaya

2018-01-01

Full Text Available The asymmetric bimodal exponential power (ABEP distribution is an extension of the generalized gamma distribution to the real line via adding two parameters that fit the shape of peakedness in bimodality on the real line. The special values of peakedness parameters of the distribution are a combination of half Laplace and half normal distributions on the real line. The distribution has two parameters fitting the height of bimodality, so capacity of bimodality is enhanced by using these parameters. Adding a skewness parameter is considered to model asymmetry in data. The location-scale form of this distribution is proposed. The Fisher information matrix of these parameters in ABEP is obtained explicitly. Properties of ABEP are examined. Real data examples are given to illustrate the modelling capacity of ABEP. The replicated artificial data from maximum likelihood estimates of parameters of ABEP and other distributions having an algorithm for artificial data generation procedure are provided to test the similarity with real data. A brief simulation study is presented.

Visualisation and characterisation of heterogeneous bimodal PDMS networks

DEFF Research Database (Denmark)

Bahrt, Frederikke; Daugaard, Anders Egede; Fleury, Clemence

2014-01-01

The existence of short-chain domains in heterogeneous bimodal PDMS networks has been confirmed visually, for the first time, through confocal fluorescence microscopy. The networks were prepared using a controlled reaction scheme where short PDMS chains were reacted below the gelation point...... bimodal networks with short-chain domains within a long-chain network. The average sizes of the short-chain domains were found to vary from 2.1 to 5.7 mm depending on the short-chain content. The visualised network structure could be correlated thereafter to the elastic properties, which were determined...... by rheology. All heterogeneous bimodal networks displayed significantly lower moduli than mono-modal PDMS elastomers prepared from the long polymer chains. Low-loss moduli as well as low-sol fractions indicate that low-elastic moduli can be obtained without compromising the network's structure...

Bimodal magmatism produced by progressively inhibited crustal assimilation 2 (PICA)

NARCIS (Netherlands)

Meade, F.C.; Troll, V.R.; Ellam, R.M.; Freda, C.; Font Morales, L.; Donaldson, C.H.; Klonowska, I.

2014-01-01

The origin of bimodal (mafic-felsic) rock suites is a fundamental question in volcanology. Here we use major and trace elements, high-resolution Sr, Nd and Pb isotope analyses, experimental petrology and thermodynamic modelling to investigate bimodal magmatism at the iconic Carlingford Igneous

Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

Science.gov (United States)

Gao, Lin; Sun, Jihong; Li, Yuzhen

2011-08-01

The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N 2 adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation ft= ktn was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties.

The NASA Advanced Space Power Systems Project

Science.gov (United States)

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.

Event-related potentials to visual, auditory, and bimodal (combined auditory-visual) stimuli.

Science.gov (United States)

Isoğlu-Alkaç, Ummühan; Kedzior, Karina; Keskindemirci, Gonca; Ermutlu, Numan; Karamursel, Sacit

2007-02-01

The purpose of this study was to investigate the response properties of event related potentials to unimodal and bimodal stimulations. The amplitudes of N1 and P2 were larger during bimodal evoked potentials (BEPs) than auditory evoked potentials (AEPs) in the anterior sites and the amplitudes of P1 were larger during BEPs than VEPs especially at the parieto-occipital locations. Responses to bimodal stimulation had longer latencies than responses to unimodal stimulation. The N1 and P2 components were larger in amplitude and longer in latency during the bimodal paradigm and predominantly occurred at the anterior sites. Therefore, the current bimodal paradigm can be used to investigate the involvement and location of specific neural generators that contribute to higher processing of sensory information. Moreover, this paradigm may be a useful tool to investigate the level of sensory dysfunctions in clinical samples.

Coordinating Space Nuclear Research Advancement and Education

International Nuclear Information System (INIS)

Bess, John D.; Webb, Jonathon A.; Gross, Brian J.; Craft, Aaron E.

2009-01-01

The advancement of space exploration using nuclear science and technology has been a goal sought by many individuals over the years. The quest to enable space nuclear applications has experienced many challenges such as funding restrictions; lack of political, corporate, or public support; and limitations in educational opportunities. The Center for Space Nuclear Research (CSNR) was established at the Idaho National Laboratory (INL) with the mission to address the numerous challenges and opportunities relevant to the promotion of space nuclear research and education.1 The CSNR is operated by the Universities Space Research Association and its activities are overseen by a Science Council comprised of various representatives from academic and professional entities with space nuclear experience. Program participants in the CSNR include academic researchers and students, government representatives, and representatives from industrial and corporate entities. Space nuclear educational opportunities have traditionally been limited to various sponsored research projects through government agencies or industrial partners, and dedicated research centers. Centralized research opportunities are vital to the growth and development of space nuclear advancement. Coordinated and focused research plays a key role in developing the future leaders in the space nuclear field. The CSNR strives to synchronize research efforts and provide means to train and educate students with skills to help them excel as leaders.

Nonlatching positive feedback enables robust bimodality by decoupling expression noise from the mean

Energy Technology Data Exchange (ETDEWEB)

Razooky, Brandon S. [Rockefeller Univ., New York, NY (United States). Lab. of Virology and Infectious Disease; Gladstone Institutes (Virology and Immunology), San Francisco, CA (United States); Univ. of California, San Francisco, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Univ. of Tennessee, Knoxville, TN (United States). Bredesen Center for Interdisciplinary; Cao, Youfang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hansen, Maike M. K. [Gladstone Institutes (Virology and Immunology), San Francisco, CA (United States); Perelson, Alan S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Simpson, Michael L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Univ. of Tennessee, Knoxville, TN (United States). Bredesen Center for Interdisciplinary; Weinberger, Leor S. [Gladstone Institutes (Virology and Immunology), San Francisco, CA (United States); Univ. of California, San Francisco, CA (United States). Dept. of Biochemistry and Biophysics; Univ. of California, San Francisco, CA (United States). QB3: California Inst. of Quantitative Biosciences; Univ. of California, San Francisco, CA (United States). Dept. of Pharmaceutical Chemistry

2017-10-18

Fundamental to biological decision-making is the ability to generate bimodal expression patterns where two alternate expression states simultaneously exist. Here in this study, we use a combination of single-cell analysis and mathematical modeling to examine the sources of bimodality in the transcriptional program controlling HIV’s fate decision between active replication and viral latency. We find that the HIV Tat protein manipulates the intrinsic toggling of HIV’s promoter, the LTR, to generate bimodal ON-OFF expression, and that transcriptional positive feedback from Tat shifts and expands the regime of LTR bimodality. This result holds for both minimal synthetic viral circuits and full-length virus. Strikingly, computational analysis indicates that the Tat circuit’s non-cooperative ‘non-latching’ feedback architecture is optimized to slow the promoter’s toggling and generate bimodality by stochastic extinction of Tat. In contrast to the standard Poisson model, theory and experiment show that non-latching positive feedback substantially dampens the inverse noise-mean relationship to maintain stochastic bimodality despite increasing mean-expression levels. Given the rapid evolution of HIV, the presence of a circuit optimized to robustly generate bimodal expression appears consistent with the hypothesis that HIV’s decision between active replication and latency provides a viral fitness advantage. More broadly, the results suggest that positive-feedback circuits may have evolved not only for signal amplification but also for robustly generating bimodality by decoupling expression fluctuations (noise) from mean expression levels.

A HYPOTHESIS FOR THE COLOR BIMODALITY OF JUPITER TROJANS

Energy Technology Data Exchange (ETDEWEB)

Wong, Ian; Brown, Michael E., E-mail: iwong@caltech.edu [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)

2016-10-01

One of the most enigmatic and hitherto unexplained properties of Jupiter Trojans is their bimodal color distribution. This bimodality is indicative of two sub-populations within the Trojans, which have distinct size distributions. In this paper, we present a simple, plausible hypothesis for the origin and evolution of the two Trojan color sub-populations. In the framework of dynamical instability models of early solar system evolution, which suggest a common primordial progenitor population for both Trojans and Kuiper Belt objects, we use observational constraints to assert that the color bimodalities evident in both minor body populations developed within the primordial population prior to the onset of instability. We show that, beginning with an initial composition of rock and ices, location-dependent volatile loss through sublimation in this primordial population could have led to sharp changes in the surface composition with heliocentric distance. We propose that the depletion or retention of H{sub 2}S ice on the surface of these objects was the key factor in creating an initial color bimodality. Objects that retained H{sub 2}S on their surfaces developed characteristically redder colors upon irradiation than those that did not. After the bodies from the primordial population were scattered and emplaced into their current positions, they preserved this primordial color bimodality to the present day. We explore predictions of the volatile loss model—in particular, the effect of collisions within the Trojan population on the size distributions of the two sub-populations—and propose further experimental and observational tests of our hypothesis.

A HYPOTHESIS FOR THE COLOR BIMODALITY OF JUPITER TROJANS

International Nuclear Information System (INIS)

Wong, Ian; Brown, Michael E.

2016-01-01

One of the most enigmatic and hitherto unexplained properties of Jupiter Trojans is their bimodal color distribution. This bimodality is indicative of two sub-populations within the Trojans, which have distinct size distributions. In this paper, we present a simple, plausible hypothesis for the origin and evolution of the two Trojan color sub-populations. In the framework of dynamical instability models of early solar system evolution, which suggest a common primordial progenitor population for both Trojans and Kuiper Belt objects, we use observational constraints to assert that the color bimodalities evident in both minor body populations developed within the primordial population prior to the onset of instability. We show that, beginning with an initial composition of rock and ices, location-dependent volatile loss through sublimation in this primordial population could have led to sharp changes in the surface composition with heliocentric distance. We propose that the depletion or retention of H 2 S ice on the surface of these objects was the key factor in creating an initial color bimodality. Objects that retained H 2 S on their surfaces developed characteristically redder colors upon irradiation than those that did not. After the bodies from the primordial population were scattered and emplaced into their current positions, they preserved this primordial color bimodality to the present day. We explore predictions of the volatile loss model—in particular, the effect of collisions within the Trojan population on the size distributions of the two sub-populations—and propose further experimental and observational tests of our hypothesis.

BDVC (Bimodal Database of Violent Content): A database of violent audio and video

Science.gov (United States)

Rivera Martínez, Jose Luis; Mijes Cruz, Mario Humberto; Rodríguez Vázqu, Manuel Antonio; Rodríguez Espejo, Luis; Montoya Obeso, Abraham; García Vázquez, Mireya Saraí; Ramírez Acosta, Alejandro Álvaro

2017-09-01

Nowadays there is a trend towards the use of unimodal databases for multimedia content description, organization and retrieval applications of a single type of content like text, voice and images, instead bimodal databases allow to associate semantically two different types of content like audio-video, image-text, among others. The generation of a bimodal database of audio-video implies the creation of a connection between the multimedia content through the semantic relation that associates the actions of both types of information. This paper describes in detail the used characteristics and methodology for the creation of the bimodal database of violent content; the semantic relationship is stablished by the proposed concepts that describe the audiovisual information. The use of bimodal databases in applications related to the audiovisual content processing allows an increase in the semantic performance only and only if these applications process both type of content. This bimodal database counts with 580 audiovisual annotated segments, with a duration of 28 minutes, divided in 41 classes. Bimodal databases are a tool in the generation of applications for the semantic web.

Speech Recognition and Cognitive Skills in Bimodal Cochlear Implant Users

Science.gov (United States)

Hua, Håkan; Johansson, Björn; Magnusson, Lennart; Lyxell, Björn; Ellis, Rachel J.

2017-01-01

Purpose: To examine the relation between speech recognition and cognitive skills in bimodal cochlear implant (CI) and hearing aid users. Method: Seventeen bimodal CI users (28-74 years) were recruited to the study. Speech recognition tests were carried out in quiet and in noise. The cognitive tests employed included the Reading Span Test and the…

Measuring oxygen uptake in fishes with bimodal respiration.

Science.gov (United States)

Lefevre, S; Bayley, M; McKenzie, D J

2016-01-01

Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. © 2015 The Fisheries Society of the British Isles.

Matching Automatic Gain Control Across Devices in Bimodal Cochlear Implant Users.

Science.gov (United States)

Veugen, Lidwien C E; Chalupper, Josef; Snik, Ad F M; Opstal, A John van; Mens, Lucas H M

2016-01-01

The purpose of this study was to improve bimodal benefit in listeners using a cochlear implant (CI) and a hearing aid (HA) in contralateral ears, by matching the time constants and the number of compression channels of the automatic gain control (AGC) of the HA to the CI. Equivalent AGC was hypothesized to support a balanced loudness for dynamically changing signals like speech and improve bimodal benefit for speech understanding in quiet and with noise presented from the side(s) at 90 degree. Fifteen subjects participated in the study, all using the same Advanced Bionics Harmony CI processor and HA (Phonak Naida S IX UP). In a 3-visit crossover design with 4 weeks between sessions, performance was measured using a HA with a standard AGC (syllabic multichannel compression with 1 ms attack time and 50 ms release time) or an AGC that was adjusted to match that of the CI processor (dual AGC broadband compression, 3 and 240 msec attack time, 80 and 1500 msec release time). In all devices, the AGC was activated above the threshold of 63 dB SPL. The authors balanced loudness across the devices for soft and loud input sounds in 3 frequency bands (0 to 548, 548 to 1000, and >1000 Hz). Speech understanding was tested in free field in quiet and in noise for three spatial speaker configurations, with target speech always presented from the front. Single-talker noise was either presented from the CI side or the HA side, or uncorrelated stationary speech-weighted noise or single-talker noise was presented from both sides. Questionnaires were administered to assess differences in perception between the two bimodal fittings. Significant bimodal benefit over the CI alone was only found for the AGC-matched HA for the speech tests with single-talker noise. Compared with the standard HA, matched AGC characteristics significantly improved speech understanding in single-talker noise by 1.9 dB when noise was presented from the HA side. AGC matching increased bimodal benefit

Medical technology advances from space research

Science.gov (United States)

Pool, S. L.

1972-01-01

Details of medical research and development programs, particularly an integrated medical laboratory, as derived from space technology are given. The program covers digital biotelemetry systems, automatic visual field mapping equipment, sponge electrode caps for clinical electroencephalograms, and advanced respiratory analysis equipment. The possibility of using the medical laboratory in ground based remote areas and regional health care facilities, as well as long duration space missions is discussed.

'Bimodal' NTR and LANTR propulsion for human missions to Mars/Phobos

International Nuclear Information System (INIS)

Borowski, Stanley K.; Dudzinski, Leonard A.; McGuire, Melissa L.

1999-01-01

The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars due to its high specific impulse (Isp ∼850-1000 s) and attractive engine thrust-to-weight ratio (∼3-10). Because only a miniscule amount of enriched uranium-235 fuel is consumed in a NTR during the primary propulsion maneuvers of a typical Mars mission, engines configured for both propulsive thrust and modest power generation (referred to as 'bimodal' operation) provide the basis for a robust, 'power-rich' stage enabling propulsive Mars capture and reuse capability. A family of modular 'bimodal' NTR (BNTR) vehicles are described which utilize a common 'core' stage powered by three 66.7 kN (∼15 klbf) BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration/reliquification system for long term, 'zero-boiloff' liquid hydrogen (LH 2 ) storage, and high data rate communications. Compared to other propulsion options, a Mars mission architecture using BNTR transfer vehicles requires fewer transportation system elements which reduces mission mass, cost and risk because of simplified space operations. For difficult Mars options, such as a Phobos rendezvous and sample return mission, volume (not mass) constraints limit the performance of the 'all LH 2 ' BNTR stage. The use of ''LOX-augmented' NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen (O/H) mixture ratio (MR) of 0.5, helps to increase 'bulk' propellant density and total thrust during the trans-Mars injection (TMI) burn. On all subsequent burns, the bimodal LANTR engines operate on LH 2 only (MR=0) to maximize vehicle performance while staying within the mass limits of two ∼80 t 'Magnum' heavy lift launch vehicles (HLLVs)

Advanced Space Radiation Detector Technology Development

Science.gov (United States)

Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

2013-01-01

The advanced space radiation detector development team at the NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

International Nuclear Information System (INIS)

Gao Lin; Sun Jihong; Li Yuzhen

2011-01-01

The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N 2 adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation f t =kt n was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties. - Graphical abstract: Loading (A) and release profiles (B) of aspirin in N-BMMs and N-MCM-41 indicated that BMMs have more drug loading capacity and faster release rate than that MCM-41. Highlights: → Bimodal mesoporous silicas (BMMs) and MCM-41 modified with amino group via post-treatment procedure. → Loading and release profiles of aspirin in modified BMMs and MCM-41. → Modified BMMs have more drug loading capacity and faster release rate than that modified MCM-41.

Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

Directory of Open Access Journals (Sweden)

Daniel Kiracofe

2013-06-01

Full Text Available One of the key goals in atomic force microscopy (AFM imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors explore the use of higher eigenmodes in bimodal AFM (e.g., exciting the first and fourth eigenmodes. It is found that such operation leads to interesting contrast reversals compared to traditional bimodal AFM. A series of experiments and numerical simulations shows that the primary cause of the contrast reversals is not the choice of eigenmode itself (e.g., second versus fourth, but rather the relative kinetic energy between the higher eigenmode and the first eigenmode. This leads to the identification of three distinct imaging regimes in bimodal AFM. This result, which is applicable even to traditional bimodal AFM, should allow researchers to choose cantilever and operating parameters in a more rational manner in order to optimize resolution and contrast during nanoscale imaging of materials.

Bimodal distribution of glucose is not universally useful for diagnosing diabetes

DEFF Research Database (Denmark)

Vistisen, Dorte; Colagiuri, Stephen; Borch-Johnsen, Knut

2009-01-01

OBJECTIVE: Bimodality in the distribution of glucose has been used to define the cut point for the diagnosis of diabetes. Previous studies on bimodality have primarily been in populations with a high prevalence of type 2 diabetes, including one study in a white Caucasian population. All studies i...

Advanced Autonomous Systems for Space Operations

Science.gov (United States)

Gross, A. R.; Smith, B. D.; Muscettola, N.; Barrett, A.; Mjolssness, E.; Clancy, D. J.

2002-01-01

New missions of exploration and space operations will require unprecedented levels of autonomy to successfully accomplish their objectives. Inherently high levels of complexity, cost, and communication distances will preclude the degree of human involvement common to current and previous space flight missions. With exponentially increasing capabilities of computer hardware and software, including networks and communication systems, a new balance of work is being developed between humans and machines. This new balance holds the promise of not only meeting the greatly increased space exploration requirements, but simultaneously dramatically reducing the design, development, test, and operating costs. New information technologies, which take advantage of knowledge-based software, model-based reasoning, and high performance computer systems, will enable the development of a new generation of design and development tools, schedulers, and vehicle and system health management capabilities. Such tools will provide a degree of machine intelligence and associated autonomy that has previously been unavailable. These capabilities are critical to the future of advanced space operations, since the science and operational requirements specified by such missions, as well as the budgetary constraints will limit the current practice of monitoring and controlling missions by a standing army of ground-based controllers. System autonomy capabilities have made great strides in recent years, for both ground and space flight applications. Autonomous systems have flown on advanced spacecraft, providing new levels of spacecraft capability and mission safety. Such on-board systems operate by utilizing model-based reasoning that provides the capability to work from high-level mission goals, while deriving the detailed system commands internally, rather than having to have such commands transmitted from Earth. This enables missions of such complexity and communication` distances as are not

An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

International Nuclear Information System (INIS)

He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

2014-01-01

The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ⪢1 and |m−1|⪡1) and the Beer–Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's S B (J-S B ) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-S B and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-S B function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available. - Highlights: • Bimodal PSDs are retrieved by ACO based on probability density function accurately. • J-S B and M-β functions can be used as the versatile function to recover bimodal PSDs. • Bimodal aerosol PSDs can be estimated by J-S B function more reasonably

Why advanced computing? The key to space-based operations

Science.gov (United States)

Phister, Paul W., Jr.; Plonisch, Igor; Mineo, Jack

2000-11-01

The 'what is the requirement?' aspect of advanced computing and how it relates to and supports Air Force space-based operations is a key issue. In support of the Air Force Space Command's five major mission areas (space control, force enhancement, force applications, space support and mission support), two-fifths of the requirements have associated stringent computing/size implications. The Air Force Research Laboratory's 'migration to space' concept will eventually shift Science and Technology (S&T) dollars from predominantly airborne systems to airborne-and-space related S&T areas. One challenging 'space' area is in the development of sophisticated on-board computing processes for the next generation smaller, cheaper satellite systems. These new space systems (called microsats or nanosats) could be as small as a softball, yet perform functions that are currently being done by large, vulnerable ground-based assets. The Joint Battlespace Infosphere (JBI) concept will be used to manage the overall process of space applications coupled with advancements in computing. The JBI can be defined as a globally interoperable information 'space' which aggregates, integrates, fuses, and intelligently disseminates all relevant battlespace knowledge to support effective decision-making at all echelons of a Joint Task Force (JTF). This paper explores a single theme -- on-board processing is the best avenue to take advantage of advancements in high-performance computing, high-density memories, communications, and re-programmable architecture technologies. The goal is to break away from 'no changes after launch' design to a more flexible design environment that can take advantage of changing space requirements and needs while the space vehicle is 'on orbit.'

Advanced Hybrid On-Board Data Processor - SpaceCube 2.0

Data.gov (United States)

National Aeronautics and Space Administration — Develop advanced on-board processing to meet the requirements of the Decadal Survey missions: advanced instruments (hyper-spectral, SAR, etc) require advanced...

Corredor Bimodal Cafetero

OpenAIRE

Duque Escobar, Gonzalo

2015-01-01

El Corredor Bimodal Cafetero es un proyecto de infraestructura estratégica que articula la Hidrovía del Magdalena con el Corredor Férreo del río Cauca, inscrito en el Plan Nacional de Desarrollo 2014/2018 y financiable con la salida de 30 mil toneladas diarias de carbón andino a la cuenca del Pacífico. Incluye el Túnel Cumanday para cruzar la Cordillera Central, el Ferrocarril Cafetero de 150 km y 3% de pendiente entre La Dorada y el Km 41, y la Transversal Cafetera de 108 km para una vía de...

Development of a Prototype Web GIS-Based Disaster Management System for Safe Operation of the Next Generation Bimodal Tram, South Korea—Focused Flooding and Snowfall

Directory of Open Access Journals (Sweden)

Won Seok Jang

2014-04-01

Full Text Available The Korea Railroad Research Institute (KRRI has developed a bimodal tram and advanced bus rapid transit (BRT system which is an optimized public transit system created by mixing the railway’s punctual operation and the bus’ easy and convenient access. The bimodal tram system provides mass-transportation service with an eco-friendly and human-centered approach. Natural disasters have been increasing worldwide in recent years, including floods, snow, and typhoons disasters. Flooding is the most frequent natural disaster in many countries and is increasingly a concern with climate change; it seriously affects people’s lives and productivity, causing considerable economic loss and significant damage. Enhanced conventional disaster management systems are needed to support comprehensive actions to secure safety and convenience. The objective of this study is to develop a prototype version of a Web GIS-based bimodal tram disaster management system (BTDMS using the Storm Water Management Model (SWMM 5.0 to enhance on-time operation and safety of the bimodal tram system. The BTDMS was tested at the bimodal tram test railroad by simulating probable maximum flood (PMF and snow melting for forecasting flooding and snow covered roads. This result could provide the basis for plans to protect against flooding disasters and snow covered roads in operating the bimodal tram system. The BTDMS will be used to assess and predict weather impacts on roadway conditions and operations and thus has the potential to influence economic growth. The methodology presented in this paper makes it possible to manage impacts of flooding and snowfall on urban transportation and enhance operation of the bimodal tram system. Such a methodology based on modeling could be created for most metropolitan areas in Korea and in many other countries.

Advanced Gas Sensing Technology for Space Suits, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Advanced space suits require lightweight, low-power, durable sensors for monitoring critical life support materials. No current compact sensors have the tolerance...

A course in bimodal provability logic

NARCIS (Netherlands)

Visser, A.

The aim of the present paper is twofold: first I am somewhat dissatisfied with current treatments of Bimodal Provability Logic: the models employed there are singled out by certain syntactical conditions, moreover they validate the logics under consideration only locally. In this paper I give a

Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

Science.gov (United States)

Deen, David A.; Osinsky, Andrei; Miller, Ross

2014-03-01

A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection.

Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

International Nuclear Information System (INIS)

Deen, David A.; Osinsky, Andrei; Miller, Ross

2014-01-01

A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection

Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

Energy Technology Data Exchange (ETDEWEB)

Deen, David A.; Osinsky, Andrei; Miller, Ross [Agnitron Technology Incorporated, Eden Prairie, Minnesota 55346 (United States)

2014-03-03

A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection.

National Space Weather Program Advances on Several Fronts

Science.gov (United States)

Gunzelman, Mark; Babcock, Michael

2008-10-01

The National Space Weather Program (NSWP; http://www.nswp.gov) is a U.S. federal government interagency initiative through the Office of the Federal Coordinator for Meteorology that was created to speed the improvement of space weather services for the nation. The Committee for Space Weather (CSW) under the NSWP has continued to advance the program on a number of fronts over the past 12 months.

Bimodal atomic force microscopy imaging of isolated antibodies in air and liquids

International Nuclear Information System (INIS)

MartInez, N F; Lozano, J R; Herruzo, E T; Garcia, F; Garcia, R; Richter, C; Sulzbach, T

2008-01-01

We have developed a dynamic atomic force microscopy (AFM) method based on the simultaneous excitation of the first two flexural modes of the cantilever. The instrument, called a bimodal atomic force microscope, allows us to resolve the structural components of antibodies in both monomer and pentameric forms. The instrument operates in both high and low quality factor environments, i.e., air and liquids. We show that under the same experimental conditions, bimodal AFM is more sensitive to compositional changes than amplitude modulation AFM. By using theoretical and numerical methods, we study the material contrast sensitivity as well as the forces applied on the sample during bimodal AFM operation

Early Bimodal Stimulation Benefits Language Acquisition for Children With Cochlear Implants.

Science.gov (United States)

Moberly, Aaron C; Lowenstein, Joanna H; Nittrouer, Susan

2016-01-01

Adding a low-frequency acoustic signal to the cochlear implant (CI) signal (i.e., bimodal stimulation) for a period of time early in life improves language acquisition. Children must acquire sensitivity to the phonemic units of language to develop most language-related skills, including expressive vocabulary, working memory, and reading. Acquiring sensitivity to phonemic structure depends largely on having refined spectral (frequency) representations available in the signal, which does not happen with CIs alone. Combining the low-frequency acoustic signal available through hearing aids with the CI signal can enhance signal quality. A period with this bimodal stimulation has been shown to improve language skills in very young children. This study examined whether these benefits persist into childhood. Data were examined for 48 children with CIs implanted under age 3 years, participating in a longitudinal study. All children wore hearing aids before receiving a CI, but upon receiving a first CI, 24 children had at least 1 year of bimodal stimulation (Bimodal group), and 24 children had only electric stimulation subsequent to implantation (CI-only group). Measures of phonemic awareness were obtained at second and fourth grades, along with measures of expressive vocabulary, working memory, and reading. Children in the Bimodal group generally performed better on measures of phonemic awareness, and that advantage was reflected in other language measures. Having even a brief period of time early in life with combined electric-acoustic input provides benefits to language learning into childhood, likely because of the enhancement in spectral representations provided.

Bimodal emotion congruency is critical to preverbal infants' abstract rule learning.

Science.gov (United States)

Tsui, Angeline Sin Mei; Ma, Yuen Ki; Ho, Anna; Chow, Hiu Mei; Tseng, Chia-huei

2016-05-01

Extracting general rules from specific examples is important, as we must face the same challenge displayed in various formats. Previous studies have found that bimodal presentation of grammar-like rules (e.g. ABA) enhanced 5-month-olds' capacity to acquire a rule that infants failed to learn when the rule was presented with visual presentation of the shapes alone (circle-triangle-circle) or auditory presentation of the syllables (la-ba-la) alone. However, the mechanisms and constraints for this bimodal learning facilitation are still unknown. In this study, we used audio-visual relation congruency between bimodal stimulation to disentangle possible facilitation sources. We exposed 8- to 10-month-old infants to an AAB sequence consisting of visual faces with affective expressions and/or auditory voices conveying emotions. Our results showed that infants were able to distinguish the learned AAB rule from other novel rules under bimodal stimulation when the affects in audio and visual stimuli were congruently paired (Experiments 1A and 2A). Infants failed to acquire the same rule when audio-visual stimuli were incongruently matched (Experiment 2B) and when only the visual (Experiment 1B) or the audio (Experiment 1C) stimuli were presented. Our results highlight that bimodal facilitation in infant rule learning is not only dependent on better statistical probability and redundant sensory information, but also the relational congruency of audio-visual information. A video abstract of this article can be viewed at https://m.youtube.com/watch?v=KYTyjH1k9RQ. © 2015 John Wiley & Sons Ltd.

Dynamical and statistical bimodality in nuclear fragmentation

Science.gov (United States)

Mallik, S.; Chaudhuri, G.; Gulminelli, F.

2018-02-01

The origin of bimodal behavior in the residue distribution experimentally measured in heavy ion reactions is reexamined using Boltzmann-Uehling-Uhlenbeck simulations. We suggest that, depending on the incident energy and impact parameter of the reaction, both entrance channel and exit channel effects can be at the origin of the observed behavior. Specifically, fluctuations in the reaction mechanism induced by fluctuations in the collision rate, as well as thermal bimodality directly linked to the nuclear liquid-gas phase transition, are observed in our simulations. Both phenomenologies were previously proposed in the literature but presented as incompatible and contradictory interpretations of the experimental measurements. These results indicate that heavy ion collisions at intermediate energies can be viewed as a powerful tool to study both bifurcations induced by out-of-equilibrium critical phenomena, as well as finite-size precursors of thermal phase transitions.

The Economics of Advanced In-Space Propulsion

Science.gov (United States)

Bangalore, Manju; Dankanich, John

2016-01-01

The cost of access to space is the single biggest driver is commercial space sector. NASA continues to invest in both launch technology and in-space propulsion. Low-cost launch systems combined with advanced in-space propulsion offer the greatest potential market capture. Launch market capture is critical to national security and has a significant impact on domestic space sector revenue. NASA typically focuses on pushing the limits on performance. However, the commercial market is driven by maximum net revenue (profits). In order to maximum the infusion of NASA investments, the impact on net revenue must be known. As demonstrated by Boeing's dual launch, the Falcon 9 combined with all Electric Propulsion (EP) can dramatically shift the launch market from foreign to domestic providers.

Deaf Children's Bimodal Bilingualism and Education

Science.gov (United States)

Swanwick, Ruth

2016-01-01

This paper provides an overview of the research into deaf children's bilingualism and bilingual education through a synthesis of studies published over the last 15 years. This review brings together the linguistic and pedagogical work on bimodal bilingualism to inform educational practice. The first section of the review provides a synthesis of…

An overview of DARPA's advanced space technology program

Science.gov (United States)

Nicastri, E.; Dodd, J.

1993-02-01

The Defense Advanced Research Projects Agency (DARPA) is the central research and development organization of the DoD and, as such, has the primary responsibility for the maintenance of U.S. technological superiority over potential adversaries. DARPA's programs focus on technology development and proof-of-concept demonstrations of both evolutionary and revolutionary approaches for improved strategic, conventional, rapid deployment and sea power forces, and on the scientific investigation into advanced basic technologies of the future. DARPA can move quickly to exploit new ideas and concepts by working directly with industry and universities. For four years, DARPA's Advanced Space Technology Program (ASTP) has addressed various ways to improve the performance of small satellites and launch vehicles. The advanced technologies that are being and will be developed by DARPA for small satellites can be used just as easily on large satellites. The primary objective of the ASTP is to enhance support to operational commanders by developing and applying advanced technologies that will provide cost-effective, timely, flexible, and responsive space systems. Fundamental to the ASTP effort is finding new ways to do business with the goal of quickly inserting new technologies into DoD space systems while reducing cost. In our view, these methods are prime examples of what may be termed 'technology leveraging.' The ASTP has initiated over 50 technology projects, many of which were completed and transitioned to users. The objectives are to quickly qualify these higher risk technologies for use on future programs and reduce the risk of inserting these technologies into major systems, and to provide the miniaturized systems that would enable smaller satellites to have significant - rather than limited - capability. Only a few of the advanced technologies are described, the majority of which are applicable to both large and small satellites.

Heuristics Applied in the Development of Advanced Space Mission Concepts

Science.gov (United States)

Nilsen, Erik N.

1998-01-01

Advanced mission studies are the first step in determining the feasibility of a given space exploration concept. A space scientist develops a science goal in the exploration of space. This may be a new observation method, a new instrument or a mission concept to explore a solar system body. In order to determine the feasibility of a deep space mission, a concept study is convened to determine the technology needs and estimated cost of performing that mission. Heuristics are one method of defining viable mission and systems architectures that can be assessed for technology readiness and cost. Developing a viable architecture depends to a large extent upon extending the existing body of knowledge, and applying it in new and novel ways. These heuristics have evolved over time to include methods for estimating technical complexity, technology development, cost modeling and mission risk in the unique context of deep space missions. This paper examines the processes involved in performing these advanced concepts studies, and analyzes the application of heuristics in the development of an advanced in-situ planetary mission. The Venus Surface Sample Return mission study provides a context for the examination of the heuristics applied in the development of the mission and systems architecture. This study is illustrative of the effort involved in the initial assessment of an advance mission concept, and the knowledge and tools that are applied.

Advancing automation and robotics technology for the space station and the US economy

Science.gov (United States)

Cohen, A.

1985-01-01

In response to Public Law 98-371, dated July 18, 1984, the NASA Advanced Technology Advisory Committee has studied automation and rebotics for use in the space station. The Executive Overview, Volume 1 presents the major findings of the study and recommends to NASA principles for advancing automation and robotics technologies for the benefit of the space station and of the U.S. economy in general. As a result of its study, the Advanced Technology Advisory Committee believes that a key element of technology for the space station is extensive use of advanced general-purpose automation and robotics. These systems could provide the United States with important new methods of generating and exploiting space knowledge in commercial enterprises and thereby help preserve U.S. leadership in space.

Bimodal Formation Time Distribution for Infall Dark Matter Halos

Science.gov (United States)

Shi, Jingjing; Wang, Huiyuan; Mo, H. J.; Xie, Lizhi; Wang, Xiaoyu; Lapi, Andrea; Sheth, Ravi K.

2018-04-01

We use a 200 {h}-1 {Mpc} a-side N-body simulation to study the mass accretion history (MAH) of dark matter halos to be accreted by larger halos, which we call infall halos. We define a quantity {a}nf}\\equiv (1+{z}{{f}})/(1+{z}peak}) to characterize the MAH of infall halos, where {z}peak} and {z}{{f}} are the accretion and formation redshifts, respectively. We find that, at given {z}peak}, their MAH is bimodal. Infall halos are dominated by a young population at high redshift and by an old population at low redshift. For the young population, the {a}nf} distribution is narrow and peaks at about 1.2, independent of {z}peak}, while for the old population, the peak position and width of the {a}nf} distribution both increase with decreasing {z}peak} and are both larger than those of the young population. This bimodal distribution is found to be closely connected to the two phases in the MAHs of halos. While members of the young population are still in the fast accretion phase at z peak, those of the old population have already entered the slow accretion phase at {z}peak}. This bimodal distribution is not found for the whole halo population, nor is it seen in halo merger trees generated with the extended Press–Schechter formalism. The infall halo population at {z}peak} are, on average, younger than the whole halo population of similar masses identified at the same redshift. We discuss the implications of our findings in connection to the bimodal color distribution of observed galaxies and to the link between central and satellite galaxies.

How the bimodal format of presentation affects working memory: an overview.

Science.gov (United States)

Mastroberardino, Serena; Santangelo, Valerio; Botta, Fabiano; Marucci, Francesco S; Olivetti Belardinelli, Marta

2008-03-01

The best format in which information that has to be recalled is presented has been investigated in several studies, which focused on the impact of bimodal stimulation on working memory performance. An enhancement of participant's performance in terms of correct recall has been repeatedly found, when bimodal formats of presentation (i.e., audiovisual) were compared to unimodal formats (i.e, either visual or auditory), in providing implications for multimedial learning. Several theoretical frameworks have been suggested in order to account for the bimodal advantage, ranging from those emphasizing early stages of processing (such as automatic alerting effects or multisensory integration processes) to those centred on late stages of processing (as postulated by the dual coding theory). The aim of this paper is to review previous contributions to this topic, providing a comprehensive theoretical framework, which is updated by the latest empirical studies.

Evidence for a bimodal distribution in human communication.

Science.gov (United States)

Wu, Ye; Zhou, Changsong; Xiao, Jinghua; Kurths, Jürgen; Schellnhuber, Hans Joachim

2010-11-02

Interacting human activities underlie the patterns of many social, technological, and economic phenomena. Here we present clear empirical evidence from Short Message correspondence that observed human actions are the result of the interplay of three basic ingredients: Poisson initiation of tasks and decision making for task execution in individual humans as well as interaction among individuals. This interplay leads to new types of interevent time distribution, neither completely Poisson nor power-law, but a bimodal combination of them. We show that the events can be separated into independent bursts which are generated by frequent mutual interactions in short times following random initiations of communications in longer times by the individuals. We introduce a minimal model of two interacting priority queues incorporating the three basic ingredients which fits well the distributions using the parameters extracted from the empirical data. The model can also embrace a range of realistic social interacting systems such as e-mail and letter communications when taking the time scale of processing into account. Our findings provide insight into various human activities both at the individual and network level. Our analysis and modeling of bimodal activity in human communication from the viewpoint of the interplay between processes of different time scales is likely to shed light on bimodal phenomena in other complex systems, such as interevent times in earthquakes, rainfall, forest fire, and economic systems, etc.

Human Exploration Mission Capabilities to the Moon, Mars, and Near Earth Asteroids Using ''Bimodal'' NTR Propulsion

International Nuclear Information System (INIS)

Stanley K. Borowski; Leonard A. Dudzinski; Melissa L. McGuire

2000-01-01

The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human exploration missions because of its high specific impulse (Isp ∼ 850 to 1000 s) and attractive engine thrust-to-weight ratio (∼ 3 to 10). Because only a minuscule amount of enriched 235 U fuel is consumed in an NRT during the primary propulsion maneuvers of a typical Mars mission, engines configured both for propulsive thrust and modest power generation (referred to as 'bimodal' operation) provide the basis for a robust, power-rich stage with efficient propulsive capture capability at the moon and near-earth asteroids (NEAs), where aerobraking cannot be utilized. A family of modular bimodal NTR (BNTR) space transfer vehicles utilize a common core stage powered by three ∼15-klb f engines that produce 50 kW(electric) of total electrical power for crew life support, high data rate communications with Earth, and an active refrigeration system for long-term, zero-boiloff liquid hydrogen (LH 2 ) storage. This paper describes details of BNTR engines and designs of vehicles using them for various missions

An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

Science.gov (United States)

He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

2014-12-01

The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ⪢1 and |m-1|⪡1) and the Beer-Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's SB (J-SB) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-SB and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-SB function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available.

Bimodal Reading: Benefits of a Talking Computer for Average and Less Skilled Readers.

Science.gov (United States)

Montali, Julie; Lewandowski, Lawrence

1996-01-01

Eighteen average readers and 18 less-skilled readers (grades 8 and 9) were presented with social studies and science passages via a computer either visually (on screen), auditorily (read by digitized voice), or bimodally (on screen, highlighted while being voiced). Less-skilled readers demonstrated comprehension in the bimodal condition equivalent…

Quantifying Young's moduli of protein fibrils and particles with bimodal force spectroscopy.

Science.gov (United States)

Gilbert, Jay; Charnley, Mirren; Cheng, Christopher; Reynolds, Nicholas P; Jones, Owen G

2017-10-19

Force spectroscopy is a means of obtaining mechanical information of individual nanometer-scale structures in composite materials, such as protein assemblies for use in consumer films or gels. As a recently developed force spectroscopy technique, bimodal force spectroscopy relates frequency shifts in cantilevers simultaneously excited at multiple frequencies to the elastic properties of the contacted material, yet its utility for quantitative characterization of biopolymer assemblies has been limited. In this study, a linear correlation between experimental frequency shift and Young's modulus of polymer films was used to calibrate bimodal force spectroscopy and quantify Young's modulus of two protein nanostructures: β-lactoglobulin fibrils and zein nanoparticles. Cross-sectional Young's modulus of protein fibrils was determined to be 1.6 GPa while the modulus of zein nanoparticles was determined as 854 MPa. Parallel measurement of β-lactoglobulin fibril by a competing pulsed-force technique found a higher cross-sectional Young's modulus, highlighting the importance of comparative calibration against known standards in both pulsed and bimodal force spectroscopies. These findings demonstrate a successful procedure for measuring mechanical properties of individual protein assemblies with potential use in biological or packaging applications using bimodal force spectroscopy.

Anhydrides-Cured Bimodal Rubber-Like Epoxy Asphalt Composites: From Thermosetting to Quasi-Thermosetting

Directory of Open Access Journals (Sweden)

Yang Kang

2016-03-01

Full Text Available The present engineering practices show the potential that epoxy asphalt composites (EACs would be a better choice to obtain long life for busy roads. To understand the service performance–related thermorheological properties of prepared bimodal anhydrides-cured rubber-like EACs (REACs, a direct tensile tester, dynamic shear rheometer and mathematical model were used. Tensile tests demonstrate that all the REACs reported here are more flexible than previously reported anhydrides-cured REACs at both 20 and 0 °C. The better flexibility is attributed to the change of bimodal networks, in which cross-linked short chains decreased and cross-linked long chains increased, relatively. Strain sweeps show that all the REACs have linear viscoelastic (LVE properties when their strains are smaller than 1.0% from −35 to 120 °C. Temperature sweeps illustrate that the thermorheological properties of REACs evolve from thermosetting to quasi-thermosetting with asphalt content, and all the REACs retain solid state and show elastic properties in the experimental temperature range. A Cole–Cole plot and Black diagram indicate that all the REACs are thermorheologically simple materials, and the master curves were constructed and well-fitted by the Generalized Logistic Sigmoidal models. This research provides a facile approach to tune the thermorheological properties of the REACs, and the cheaper quasi-thermosetting REAC facilitates their advanced applications.

Unimodal Versus Bimodal EEG-fMRI Neurofeedback of a Motor Imagery Task

Directory of Open Access Journals (Sweden)

Lorraine Perronnet

2017-04-01

Full Text Available Neurofeedback is a promising tool for brain rehabilitation and peak performance training. Neurofeedback approaches usually rely on a single brain imaging modality such as EEG or fMRI. Combining these modalities for neurofeedback training could allow to provide richer information to the subject and could thus enable him/her to achieve faster and more specific self-regulation. Yet unimodal and multimodal neurofeedback have never been compared before. In the present work, we introduce a simultaneous EEG-fMRI experimental protocol in which participants performed a motor-imagery task in unimodal and bimodal NF conditions. With this protocol we were able to compare for the first time the effects of unimodal EEG-neurofeedback and fMRI-neurofeedback versus bimodal EEG-fMRI-neurofeedback by looking both at EEG and fMRI activations. We also propose a new feedback metaphor for bimodal EEG-fMRI-neurofeedback that integrates both EEG and fMRI signal in a single bi-dimensional feedback (a ball moving in 2D. Such a feedback is intended to relieve the cognitive load of the subject by presenting the bimodal neurofeedback task as a single regulation task instead of two. Additionally, this integrated feedback metaphor gives flexibility on defining a bimodal neurofeedback target. Participants were able to regulate activity in their motor regions in all NF conditions. Moreover, motor activations as revealed by offline fMRI analysis were stronger during EEG-fMRI-neurofeedback than during EEG-neurofeedback. This result suggests that EEG-fMRI-neurofeedback could be more specific or more engaging than EEG-neurofeedback. Our results also suggest that during EEG-fMRI-neurofeedback, participants tended to regulate more the modality that was harder to control. Taken together our results shed first light on the specific mechanisms of bimodal EEG-fMRI-neurofeedback and on its added-value as compared to unimodal EEG-neurofeedback and fMRI-neurofeedback.

Bi-modal G\\"odel logic over [0,1]-valued Kripke frames

OpenAIRE

Caicedo, Xavier; Rodriguez, Ricardo Oscar

2011-01-01

We consider the G\\"odel bi-modal logic determined by fuzzy Kripke models where both the propositions and the accessibility relation are infinitely valued over the standard G\\"odel algebra [0,1] and prove strong completeness of Fischer Servi intuitionistic modal logic IK plus the prelinearity axiom with respect to this semantics. We axiomatize also the bi-modal analogues of $T,$ $S4,$ and $S5$ obtained by restricting to models over frames satisfying the [0,1]-valued versions of the structural ...

Bimodal SLD Ice Accretion on a NACA 0012 Airfoil Model

Science.gov (United States)

Potapczuk, Mark; Tsao, Jen-Ching; King-Steen, Laura

2016-01-01

This presentation describes the results of ice accretion measurements on a NACA 0012 airfoil model, from the NASA Icing Research Tunnel, using an icing cloud composed of a bimodal distribution of Supercooled Large Droplets. The data consists of photographs, laser scans of the ice surface, and measurements of the mass of ice for each icing condition. The results of ice shapes accumulated as a result of exposure to an icing cloud with a bimodal droplet distribution were compared to the ice shapes resulting from an equivalent cloud composed of a droplet distribution with a standard bell curve shape.

Center for Advanced Space Propulsion Second Annual Technical Symposium Proceedings

Science.gov (United States)

1990-01-01

The proceedings for the Center for Advanced Space Propulsion Second Annual Technical Symposium are divided as follows: Chemical Propulsion, CFD; Space Propulsion; Electric Propulsion; Artificial Intelligence; Low-G Fluid Management; and Rocket Engine Materials.

Microbubble embedded with upconversion nanoparticles as a bimodal contrast agent for fluorescence and ultrasound imaging

International Nuclear Information System (INIS)

Jin, Birui; Lin, Min; You, Minli; Xu, Feng; Lu, Tianjian; Zong, Yujin; Wan, Mingxi; Duan, Zhenfeng

2015-01-01

Bimodal imaging offers additional imaging signal thus finds wide spread application in clinical diagnostic imaging. Fluorescence/ultrasound bimodal imaging contrast agent using fluorescent dyes or quantum dots for fluorescence signal has emerged as a promising method, which however requires visible light or UV irradiation resulting in photobleaching, photoblinking, auto-fluorescence and limited tissue penetration depth. To surmount these problems, we developed a novel bimodal contrast agent using layer-by-layer assembly of upconversion nanoparticles onto the surface of microbubbles. The resulting microbubbles with average size of 2 μm provide enhanced ultrasound echo for ultrasound imaging and upconversion emission upon near infrared irradiation for fluorescence imaging. The developed bimodal contrast agent holds great potential to be applied in ultrasound target technique for targeted diseases diagnostics and therapy. (paper)

THE SLUGGS SURVEY: NGC 3115, A CRITICAL TEST CASE FOR METALLICITY BIMODALITY IN GLOBULAR CLUSTER SYSTEMS

International Nuclear Information System (INIS)

Brodie, Jean P.; Conroy, Charlie; Arnold, Jacob A.; Romanowsky, Aaron J.; Usher, Christopher; Forbes, Duncan A.; Strader, Jay

2012-01-01

Due to its proximity (9 Mpc) and the strongly bimodal color distribution of its spectroscopically well-sampled globular cluster (GC) system, the early-type galaxy NGC 3115 provides one of the best available tests of whether the color bimodality widely observed in GC systems generally reflects a true metallicity bimodality. Color bimodality has alternatively been attributed to a strongly nonlinear color-metallicity relation reflecting the influence of hot horizontal-branch stars. Here, we couple Subaru Suprime-Cam gi photometry with Keck/DEIMOS spectroscopy to accurately measure GC colors and a CaT index that measures the Ca II triplet. We find the NGC 3115 GC system to be unambiguously bimodal in both color and the CaT index. Using simple stellar population models, we show that the CaT index is essentially unaffected by variations in horizontal-branch morphology over the range of metallicities relevant to GC systems (and is thus a robust indicator of metallicity) and confirm bimodality in the metallicity distribution. We assess the existing evidence for and against multiple metallicity subpopulations in early- and late-type galaxies and conclude that metallicity bi/multimodality is common. We briefly discuss how this fundamental characteristic links directly to the star formation and assembly histories of galaxies.

THE SLUGGS SURVEY: NGC 3115, A CRITICAL TEST CASE FOR METALLICITY BIMODALITY IN GLOBULAR CLUSTER SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Brodie, Jean P.; Conroy, Charlie; Arnold, Jacob A.; Romanowsky, Aaron J. [University of California Observatories and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Usher, Christopher; Forbes, Duncan A. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Strader, Jay, E-mail: brodie@ucolick.org [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

2012-11-10

Due to its proximity (9 Mpc) and the strongly bimodal color distribution of its spectroscopically well-sampled globular cluster (GC) system, the early-type galaxy NGC 3115 provides one of the best available tests of whether the color bimodality widely observed in GC systems generally reflects a true metallicity bimodality. Color bimodality has alternatively been attributed to a strongly nonlinear color-metallicity relation reflecting the influence of hot horizontal-branch stars. Here, we couple Subaru Suprime-Cam gi photometry with Keck/DEIMOS spectroscopy to accurately measure GC colors and a CaT index that measures the Ca II triplet. We find the NGC 3115 GC system to be unambiguously bimodal in both color and the CaT index. Using simple stellar population models, we show that the CaT index is essentially unaffected by variations in horizontal-branch morphology over the range of metallicities relevant to GC systems (and is thus a robust indicator of metallicity) and confirm bimodality in the metallicity distribution. We assess the existing evidence for and against multiple metallicity subpopulations in early- and late-type galaxies and conclude that metallicity bi/multimodality is common. We briefly discuss how this fundamental characteristic links directly to the star formation and assembly histories of galaxies.

Use of advanced commercial ICs (COTS) for space application

International Nuclear Information System (INIS)

Strobel, D.J.; Czajkowski, D.R.; Layton, P.; Shanken, S.

1999-01-01

A product line of space-qualified radiation-tolerant ICs based on a high-volume commercial-off-the-shelf (COTS) silicon has been developed. The basic results from over 300 lots of COTS silicon, assembled and screened to Class B and Class S requirements will be presented. Intelligent use of commercial ICs engineered to improve radiation performance, is effective in introducing advanced technology to new satellite systems. Space Electronics has introduced over 125 space-qualified microelectronics standard products, that are used on over 90 space projects. (authors)

Refining Bimodal Microstructure of Materials with MSTRUCT

Czech Academy of Sciences Publication Activity Database

Matěj, Z.; Kadlecová, A.; Janeček, M.; Matějová, Lenka; Dopita, M.; Kužel, R.

2014-01-01

Roč. 29, S2 (2014), S35-S41 ISSN 0885-7156 R&D Projects: GA ČR GA14-23274S Grant - others:UK(CZ) UNCE 204023/2012 Institutional support: RVO:67985858 Keywords : XRD * bimodal * crystallite size Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.636, year: 2014

NASA universities advanced space design program, focus on nuclear engineering

International Nuclear Information System (INIS)

Lyon, W.F. III; George, J.A.; Alred, J.W.; Peddicord, K.L.

1987-01-01

In January 1985, the National Aeronautics and Space Administration (NASA), in affiliation with the Universities Space Research Association (USRA), inaugurated the NASA Universities Advanced Space Design Program. The purpose of the program was to encourage participating universities to utilize design projects for the senior and graduate level design courses that would focus on topics relevant to the nation's space program. The activities and projects being carried out under the NASA Universities Advanced Space Design Program are excellent experiences for the participants. This program is a well-conceived, well-planned effort to achieve the maximum benefit out of not only the university design experience but also of the subsequent summer programs. The students in the university design classes have the opportunity to investigate dramatic and new concepts, which at the same time have a place in a program of national importance. This program could serve as a very useful model for the development of university interaction with other federal agencies

Children with dyslexia show a reduced processing benefit from bimodal speech information compared to their typically developing peers.

Science.gov (United States)

Schaadt, Gesa; van der Meer, Elke; Pannekamp, Ann; Oberecker, Regine; Männel, Claudia

2018-01-17

During information processing, individuals benefit from bimodally presented input, as has been demonstrated for speech perception (i.e., printed letters and speech sounds) or the perception of emotional expressions (i.e., facial expression and voice tuning). While typically developing individuals show this bimodal benefit, school children with dyslexia do not. Currently, it is unknown whether the bimodal processing deficit in dyslexia also occurs for visual-auditory speech processing that is independent of reading and spelling acquisition (i.e., no letter-sound knowledge is required). Here, we tested school children with and without spelling problems on their bimodal perception of video-recorded mouth movements pronouncing syllables. We analyzed the event-related potential Mismatch Response (MMR) to visual-auditory speech information and compared this response to the MMR to monomodal speech information (i.e., auditory-only, visual-only). We found a reduced MMR with later onset to visual-auditory speech information in children with spelling problems compared to children without spelling problems. Moreover, when comparing bimodal and monomodal speech perception, we found that children without spelling problems showed significantly larger responses in the visual-auditory experiment compared to the visual-only response, whereas children with spelling problems did not. Our results suggest that children with dyslexia exhibit general difficulties in bimodal speech perception independently of letter-speech sound knowledge, as apparent in altered bimodal speech perception and lacking benefit from bimodal information. This general deficit in children with dyslexia may underlie the previously reported reduced bimodal benefit for letter-speech sound combinations and similar findings in emotion perception. Copyright © 2018 Elsevier Ltd. All rights reserved.

Estimation of Bimodal Urban Link Travel Time Distribution and Its Applications in Traffic Analysis

Directory of Open Access Journals (Sweden)

Yuxiong Ji

2015-01-01

Full Text Available Vehicles travelling on urban streets are heavily influenced by traffic signal controls, pedestrian crossings, and conflicting traffic from cross streets, which would result in bimodal travel time distributions, with one mode corresponding to travels without delays and the other travels with delays. A hierarchical Bayesian bimodal travel time model is proposed to capture the interrupted nature of urban traffic flows. The travel time distributions obtained from the proposed model are then considered to analyze traffic operations and estimate travel time distribution in real time. The advantage of the proposed bimodal model is demonstrated using empirical data, and the results are encouraging.

Advanced materials for space nuclear power systems

International Nuclear Information System (INIS)

Titran, R.H.; Grobstein, T.L.

1991-01-01

Research on monolithic refractory metal alloys and on metal matrix composites is being conducted at the NASA Lewis Research Center, Cleveland, Ohio, in support of advanced space power systems. The overall philosophy of the research is to develop and characterize new high-temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites (Gr/Cu) for heat rejection fins, and tungsten fiber reinforced niobium matrix composites (W/NB) for fuel containment and structural supports) considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications

Evolution of twinning in extruded AZ31 alloy with bimodal grain structure

Energy Technology Data Exchange (ETDEWEB)

Garcés, G., E-mail: ggarces@cenim.csic.es [Department of Physical Metallurgy, National Centre for Metallurgical Research CENIM-CSIC, Av. De Gregorio del Amo 8, 28040 Madrid (Spain); Oñorbe, E. [CIEMAT, Division of Structural Materials, Avenida Complutense, 40, 28040 Madrid (Spain); Gan, W. [German Engineering Materials Science Centre at MLZ, Helmholtz-Zentrum Geesthacht, Lichtebergstr. 1, D-85747 Garching (Germany); Máthis, K. [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University, KeKarlovu 5, 121 16 Praha 2 (Czech Republic); Tolnai, D. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, 21502 Geesthacht (Germany); Horváth, K. [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University, KeKarlovu 5, 121 16 Praha 2 (Czech Republic); Pérez, P.; Adeva, P. [Department of Physical Metallurgy, National Centre for Metallurgical Research CENIM-CSIC, Av. De Gregorio del Amo 8, 28040 Madrid (Spain)

2017-04-15

Twinning in extruded AZ31 alloy with a bimodal grain structure is studied under compression along the extrusion direction. This study has combined in-situ measurements during the compression tests by Synchrotron Radiation Diffraction and Acoustic Emission techniques and the evaluation of the microstructure and texture in post-mortem compression samples deformed at different strains. The microstructure of the alloy is characterized by the coexistence of large areas of fine dynamic recrystallized grains and coarse non-recrystallized grains elongated along extrusion direction. Twinning occurs initially in large elongated grains before the macroscopic yield stress which is controlled by the twinning in equiaxed dynamically recrystallized grains. - Highlights: • The AZ31 extruded at low temperature exhibits a bimodal grains structure. • Twinning takes place before macroscopic yielding in coarse non-DRXed grains. • DRXed grains controls the beginning of plasticity in magnesium alloys with bimodal grain structure.

Advanced electrostatic ion thruster for space propulsion

Science.gov (United States)

Masek, T. D.; Macpherson, D.; Gelon, W.; Kami, S.; Poeschel, R. L.; Ward, J. W.

1978-01-01

The suitability of the baseline 30 cm thruster for future space missions was examined. Preliminary design concepts for several advanced thrusters were developed to assess the potential practical difficulties of a new design. Useful methodologies were produced for assessing both planetary and earth orbit missions. Payload performance as a function of propulsion system technology level and cost sensitivity to propulsion system technology level are among the topics assessed. A 50 cm diameter thruster designed to operate with a beam voltage of about 2400 V is suggested to satisfy most of the requirements of future space missions.

MITEE-B: A compact ultra lightweight bi-modal nuclear propulsion engine for robotic planetary science missions

International Nuclear Information System (INIS)

Powell, James; Maise, George; Paniagua, John; Borowski, Stanley

2003-01-01

Nuclear thermal propulsion (NTP) enables unique new robotic planetary science missions that are impossible with chemical or nuclear electric propulsion systems. A compact and ultra lightweight bi-modal nuclear engine, termed MITEE-B (MInature ReacTor EnginE - Bi-Modal) can deliver 1000's of kilograms of propulsive thrust when it operates in the NTP mode, and many kilowatts of continuous electric power when it operates in the electric generation mode. The high propulsive thrust NTP mode enables spacecraft to land and takeoff from the surface of a planet or moon, to hop to multiple widely separated sites on the surface, and virtually unlimited flight in planetary atmospheres. The continuous electric generation mode enables a spacecraft to replenish its propellant by processing in-situ resources, provide power for controls, instruments, and communications while in space and on the surface, and operate electric propulsion units. Six examples of unique and important missions enabled by the MITEE-B engine are described, including: (1) Pluto lander and sample return; (2) Europa lander and ocean explorer; (3) Mars Hopper; (4) Jupiter atmospheric flyer; (5) SunBurn hypervelocity spacecraft; and (6) He3 mining from Uranus. Many additional important missions are enabled by MITEE-B. A strong technology base for MITEE-B already exists. With a vigorous development program, it could be ready for initial robotic science and exploration missions by 2010 AD. Potential mission benefits include much shorter in-space times, reduced IMLEO requirements, and replenishment of supplies from in-situ resources

Advanced Materials for Space Applications

Science.gov (United States)

Pater, Ruth H.; Curto, Paul A.

2005-01-01

Since NASA was created in 1958, over 6400 patents have been issued to the agency--nearly one in a thousand of all patents ever issued in the United States. A large number of these inventions have focused on new materials that have made space travel and exploration of the moon, Mars, and the outer planets possible. In the last few years, the materials developed by NASA Langley Research Center embody breakthroughs in performance and properties that will enable great achievements in space. The examples discussed below offer significant advantages for use in small satellites, i.e., those with payloads under a metric ton. These include patented products such as LaRC SI, LaRC RP 46, LaRC RP 50, PETI-5, TEEK, PETI-330, LaRC CP, TOR-LM and LaRC LCR (patent pending). These and other new advances in nanotechnology engineering, self-assembling nanostructures and multifunctional aerospace materials are presented and discussed below, and applications with significant technological and commercial advantages are proposed.

Space Station Validation of Advanced Radiation-Shielding Polymeric Materials, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — In Subtopic X11.01, NASA has identified the need to develop advanced radiation-shielding materials and systems to protect humans from the hazards of space radiation...

TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

International Nuclear Information System (INIS)

Kacprzak, Glenn G.; Churchill, Christopher W.; Nielsen, Nikole M.

2012-01-01

We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W r (2796) ≥ 0.1 Å] and 35 spectroscopically confirmed non-absorbing galaxies [W r (2796) r (2796) r (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100° and 40°, respectively. We find that the probability of detecting outflows is ∼60%, implying that winds are more commonly observed.

Nano-scale simulation based study of creep behavior of bimodal nanocrystalline face centered cubic metal.

Science.gov (United States)

Meraj, Md; Pal, Snehanshu

2017-10-11

In this paper, the creep behavior of nanocrystalline Ni having bimodal grain structure is investigated using molecular dynamics simulation. Analysis of structural evolution during the creep process has also been performed. It is observed that an increase in size of coarse grain causes improvement in creep properties of bimodal nanocrystalline Ni. Influence of bimodality (i.e., size difference between coarse and fine grains) on creep properties are found to be reduced with increasing creep temperature. The dislocation density is observed to decrease exponentially with progress of creep deformation. Grain boundary diffusion controlled creep mechanism is found to be dominant at the primary creep region and the initial part of the secondary creep region. After that shear diffusion transformation mechanism is found to be significantly responsible for deformation as bimodal nanocrystalline Ni transforms to amorphous structure with further progress of the creep process. The presence of , , and  distorted icosahedra has a significant influence on creep rate in the tertiary creep regime according to Voronoi cluster analysis.

Does bimodal stimulus presentation increase ERP components usable in BCIs?

Science.gov (United States)

Thurlings, Marieke E.; Brouwer, Anne-Marie; Van Erp, Jan B. F.; Blankertz, Benjamin; Werkhoven, Peter J.

2012-08-01

Event-related potential (ERP)-based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain activity due to multisensory integration which may be of use in BCIs. We investigated the effect of visual-tactile stimulus presentation on the chain of ERP components, BCI performance (classification accuracies and bitrates) and participants’ task performance (counting of targets). Ten participants were instructed to navigate a visual display by attending (spatially) to targets in sequences of either visual, tactile or visual-tactile stimuli. We observe that attending to visual-tactile (compared to either visual or tactile) stimuli results in an enhanced early ERP component (N1). This bimodal N1 may enhance BCI performance, as suggested by a nonsignificant positive trend in offline classification accuracies. A late ERP component (P300) is reduced when attending to visual-tactile compared to visual stimuli, which is consistent with the nonsignificant negative trend of participants’ task performance. We discuss these findings in the light of affected spatial attention at high-level compared to low-level stimulus processing. Furthermore, we evaluate bimodal BCIs from a practical perspective and for future applications.

RSMASS-D nuclear thermal propulsion and bimodal system mass models

Science.gov (United States)

King, Donald B.; Marshall, Albert C.

1997-01-01

Two relatively simple models have been developed to estimate reactor, radiation shield, and balance of system masses for a particle bed reactor (PBR) nuclear thermal propulsion concept and a cermet-core power and propulsion (bimodal) concept. The approach was based on the methodology developed for the RSMASS-D models. The RSMASS-D approach for the reactor and shield sub-systems uses a combination of simple equations derived from reactor physics and other fundamental considerations along with tabulations of data from more detailed neutron and gamma transport theory computations. Relatively simple models are used to estimate the masses of other subsystem components of the nuclear propulsion and bimodal systems. Other subsystem components include instrumentation and control (I&C), boom, safety systems, radiator, thermoelectrics, heat pipes, and nozzle. The user of these models can vary basic design parameters within an allowed range to achieve a parameter choice which yields a minimum mass for the operational conditions of interest. Estimated system masses are presented for a range of reactor power levels for propulsion for the PBR propulsion concept and for both electrical power and propulsion for the cermet-core bimodal concept. The estimated reactor system masses agree with mass predictions from detailed calculations with xx percent for both models.

User Needs and Advances in Space Wireless Sensing and Communications

Science.gov (United States)

Kegege, Obadiah

2017-01-01

Decades of space exploration and technology trends for future missions show the need for new approaches in space/planetary sensor networks, observatories, internetworking, and communications/data delivery to Earth. The User Needs to be discussed in this talk includes interviews with several scientists and reviews of mission concepts for the next generation of sensors, observatories, and planetary surface missions. These observatories, sensors are envisioned to operate in extreme environments, with advanced autonomy, whereby sometimes communication to Earth is intermittent and delayed. These sensor nodes require software defined networking capabilities in order to learn and adapt to the environment, collect science data, internetwork, and communicate. Also, some user cases require the level of intelligence to manage network functions (either as a host), mobility, security, and interface data to the physical radio/optical layer. For instance, on a planetary surface, autonomous sensor nodes would create their own ad-hoc network, with some nodes handling communication capabilities between the wireless sensor networks and orbiting relay satellites. A section of this talk will cover the advances in space communication and internetworking to support future space missions. NASA's Space Communications and Navigation (SCaN) program continues to evolve with the development of optical communication, a new vision of the integrated network architecture with more capabilities, and the adoption of CCSDS space internetworking protocols. Advances in wireless communications hardware and electronics have enabled software defined networking (DVB-S2, VCM, ACM, DTN, Ad hoc, etc.) protocols for improved wireless communication and network management. Developing technologies to fulfil these user needs for wireless communications and adoption of standardized communication/internetworking protocols will be a huge benefit to future planetary missions, space observatories, and manned missions

High Efficiency Space Power Systems Project Advanced Space-Rated Batteries

Science.gov (United States)

Reid, Concha M.

2011-01-01

Case Western Reserve University (CWRU) has an agreement with China National Offshore Oil Corporation New Energy Investment Company, Ltd. (CNOOC), under the United States-China EcoPartnerships Framework, to create a bi-national entity seeking to develop technically feasible and economically viable solutions to energy and environmental issues. Advanced batteries have been identified as one of the initial areas targeted for collaborations. CWRU invited NASA Glenn Research Center (GRC) personnel from the Electrochemistry Branch to CWRU to discuss various aspects of advanced battery development as they might apply to this partnership. Topics discussed included: the process for the selection of a battery chemistry; the establishment of an integrated development program; project management/technical interactions; new technology developments; and synergies between batteries for automotive and space operations. Additional collaborations between CWRU and NASA GRC's Electrochemistry Branch were also discussed.

Are star formation rates of galaxies bimodal?

Science.gov (United States)

Feldmann, Robert

2017-09-01

Star formation rate (SFR) distributions of galaxies are often assumed to be bimodal with modes corresponding to star-forming and quiescent galaxies, respectively. Both classes of galaxies are typically studied separately, and SFR distributions of star-forming galaxies are commonly modelled as lognormals. Using both observational data and results from numerical simulations, I argue that this division into star-forming and quiescent galaxies is unnecessary from a theoretical point of view and that the SFR distributions of the whole population can be well fitted by zero-inflated negative binomial distributions. This family of distributions has three parameters that determine the average SFR of the galaxies in the sample, the scatter relative to the star-forming sequence and the fraction of galaxies with zero SFRs, respectively. The proposed distributions naturally account for (I) the discrete nature of star formation, (II) the presence of 'dead' galaxies with zero SFRs and (III) asymmetric scatter. Excluding 'dead' galaxies, the distribution of log SFR is unimodal with a peak at the star-forming sequence and an extended tail towards low SFRs. However, uncertainties and biases in the SFR measurements can create the appearance of a bimodal distribution.

Hydrogen permeation resistant heat pipe for bi-modal reactors. Final report, October 1, 1994--September 30, 1995

International Nuclear Information System (INIS)

North, M.T.; Anderson, W.G.

1995-01-01

The principal objective of this program was to demonstrate technology that will make a sodium heat pipe tolerant of hydrogen permeation for a bimodal space reactor application. Special focus was placed on techniques which enhance the permeation of hydrogen out of the heat pipe. Specific objectives include: define the detailed requirements for the bimodal reactor application; design and fabricate a prototype heat pipe tolerant of hydrogen permeation; and test the prototype heat pipe and demonstrate that hydrogen which permeates into the heat pipe is removed or reduced to acceptable levels. The results of the program were fully successful. Analyses were performed on two different heat pipe designs and an experimental heat pipe was fabricated and tested. A model of the experimental heat pipe was developed to predict the enhancement in the hydrogen permeation rate out of the heat pipe. A significant improvement in the rate at which hydrogen permeates out of a heat pipe was predicted for the use of the special condenser geometry developed here. Agreement between the model and the experimental results was qualitatively good. Inclusion of the additional effects of fluid flow in the heat pipe are recommended for future work

Recent advances in celestial and space mechanics

CERN Document Server

Chyba, Monique

2016-01-01

This book presents recent advances in space and celestial mechanics, with a focus on the N-body problem and astrodynamics, and explores the development and application of computational techniques in both areas. It highlights the design of space transfers with various modes of propulsion, like solar sailing and low-thrust transfers between libration point orbits, as well as a broad range of targets and applications, like rendezvous with near Earth objects. Additionally, it includes contributions on the non-integrability properties of the collinear three- and four-body problem, and on general conditions for the existence of stable, minimum energy configurations in the full N-body problem. A valuable resource for physicists and mathematicians with research interests in celestial mechanics, astrodynamics and optimal control as applied to space transfers, as well as for professionals and companies in the industry.

Brain deactivation in the outperformance in bimodal tasks: an FMRI study.

Directory of Open Access Journals (Sweden)

Tzu-Ching Chiang

Full Text Available While it is known that some individuals can effectively perform two tasks simultaneously, other individuals cannot. How the brain deals with performing simultaneous tasks remains unclear. In the present study, we aimed to assess which brain areas corresponded to various phenomena in task performance. Nineteen subjects were requested to sequentially perform three blocks of tasks, including two unimodal tasks and one bimodal task. The unimodal tasks measured either visual feature binding or auditory pitch comparison, while the bimodal task required performance of the two tasks simultaneously. The functional magnetic resonance imaging (fMRI results are compatible with previous studies showing that distinct brain areas, such as the visual cortices, frontal eye field (FEF, lateral parietal lobe (BA7, and medial and inferior frontal lobe, are involved in processing of visual unimodal tasks. In addition, the temporal lobes and Brodmann area 43 (BA43 were involved in processing of auditory unimodal tasks. These results lend support to concepts of modality-specific attention. Compared to the unimodal tasks, bimodal tasks required activation of additional brain areas. Furthermore, while deactivated brain areas were related to good performance in the bimodal task, these areas were not deactivated where the subject performed well in only one of the two simultaneous tasks. These results indicate that efficient information processing does not require some brain areas to be overly active; rather, the specific brain areas need to be relatively deactivated to remain alert and perform well on two tasks simultaneously. Meanwhile, it can also offer a neural basis for biofeedback in training courses, such as courses in how to perform multiple tasks simultaneously.

How bilingualism protects the brain from aging: Insights from bimodal bilinguals.

Science.gov (United States)

Li, Le; Abutalebi, Jubin; Emmorey, Karen; Gong, Gaolang; Yan, Xin; Feng, Xiaoxia; Zou, Lijuan; Ding, Guosheng

2017-08-01

Bilingual experience can delay cognitive decline during aging. A general hypothesis is that the executive control system of bilinguals faces an increased load due to controlling two languages, and this increased load results in a more "tuned brain" that eventually creates a neural reserve. Here we explored whether such a neuroprotective effect is independent of language modality, i.e., not limited to bilinguals who speak two languages but also occurs for bilinguals who use a spoken and a signed language. We addressed this issue by comparing bimodal bilinguals to monolinguals in order to detect age-induced structural brain changes and to determine whether we can detect the same beneficial effects on brain structure, in terms of preservation of gray matter volume (GMV), for bimodal bilinguals as has been reported for unimodal bilinguals. Our GMV analyses revealed a significant interaction effect of age × group in the bilateral anterior temporal lobes, left hippocampus/amygdala, and left insula where bimodal bilinguals showed slight GMV increases while monolinguals showed significant age-induced GMV decreases. We further found through cortical surface-based measurements that this effect was present for surface area and not for cortical thickness. Moreover, to further explore the hypothesis that overall bilingualism provides neuroprotection, we carried out a direct comparison of GMV, extracted from the brain regions reported above, between bimodal bilinguals, unimodal bilinguals, and monolinguals. Bilinguals, regardless of language modality, exhibited higher GMV compared to monolinguals. This finding highlights the general beneficial effects provided by experience handling two language systems, whether signed or spoken. Hum Brain Mapp 38:4109-4124, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Space reactor safety, 1985--1995 lessons learned

International Nuclear Information System (INIS)

Marshall, A.C.

1995-01-01

Space reactor safety activities and decisions have evolved over the last decade. Important safety decisions have been made in the SP-100, Space Exploration Initiative, NEPSTP, SNTP, and Bimodal Space Reactor programs. In addition, international guidance on space reactor safety has been instituted. Space reactor safety decisions and practices have developed in the areas of inadvertent criticality, reentry, radiological release, orbital operation, programmatic, and policy. In general, the lessons learned point out the importance of carefully reviewing previous safety practices for appropriateness to space nuclear programs in general and to the specific mission under consideration

Space reactor safety, 1985--1995 lessons learned

Energy Technology Data Exchange (ETDEWEB)

Marshall, A.C.

1995-12-31

Space reactor safety activities and decisions have evolved over the last decade. Important safety decisions have been made in the SP-100, Space Exploration Initiative, NEPSTP, SNTP, and Bimodal Space Reactor programs. In addition, international guidance on space reactor safety has been instituted. Space reactor safety decisions and practices have developed in the areas of inadvertent criticality, reentry, radiological release, orbital operation, programmatic, and policy. In general, the lessons learned point out the importance of carefully reviewing previous safety practices for appropriateness to space nuclear programs in general and to the specific mission under consideration.

The Efficiency of the Bimodal System Transportation

Directory of Open Access Journals (Sweden)

Nada Štrumberger

2012-10-01

Full Text Available The development of fast railway results in an increased applicationof Trailer Train bimodal system transportation. Thetraffic costs are multiply reduced, particularly the variablecosts. On the other hand the environmental pollution from exhaustgases is also reduced. Therefore, by the year 2010 cargotransport should be preponderant~v used which would be characterisedby fast electric trains producing less noise, at lowercosts and with clean environment.

Space water electrolysis: Space Station through advance missions

Science.gov (United States)

Davenport, Ronald J.; Schubert, Franz H.; Grigger, David J.

1991-01-01

Static Feed Electrolyzer (SFE) technology can satisfy the need for oxygen (O2) and Hydrogen (H2) in the Space Station Freedom and future advanced missions. The efficiency with which the SFE technology can be used to generate O2 and H2 is one of its major advantages. In fact, the SFE is baselined for the Oxygen Generation Assembly within the Space Station Freedom's Environmental Control and Life Support System (ECLSS). In the conventional SFE process an alkaline electrolyte is contained within the matrix and is sandwiched between two porous electrodes. The electrodes and matrix make up a unitized cell core. The electrolyte provides the necessary path for the transport of water and ions between the electrodes, and forms a barrier to the diffusion of O2 and H2. A hydrophobic, microporous membrane permits water vapor to diffuse from the feed water to the cell core. This membrane separates the liquid feed water from the product H2, and, therefore, avoids direct contact of the electrodes by the feed water. The feed water is also circulated through an external heat exchanger to control the temperature of the cell.

Cermet-fueled reactors for advanced space applications

International Nuclear Information System (INIS)

Cowan, C.L.; Palmer, R.S.; Taylor, I.N.; Vaidyanathan, S.; Bhattacharyya, S.K.; Barner, J.O.

1987-12-01

Cermet-fueled nuclear reactors are attractive candidates for high-performance advanced space power systems. The cermet consists of a hexagonal matrix of a refractory metal and a ceramic fuel, with multiple tubular flow channels. The high performance characteristics of the fuel matrix come from its high strength at elevated temperatures and its high thermal conductivity. The cermet fuel concept evolved in the 1960s with the objective of developing a reactor design that could be used for a wide range of mobile power generating sytems, including both Brayton and Rankine power conversion cycles. High temperature thermal cycling tests for the cermet fuel were carried out by General Electric as part of the 710 Project (General Electric 1966), and by Argonne National Laboratory in the Direct Nuclear Rocket Program (1965). Development programs for cermet fuel are currently under way at Argonne National Laboratory and Pacific Northwest Laboratory. The high temperature qualification tests from the 1960s have provided a base for the incorporation of cermet fuel in advanced space applications. The status of the cermet fuel development activities and descriptions of the key features of the cermet-fueled reactor design are summarized in this paper

Advanced Learning Space as an Asset for Students with Disabilities

Science.gov (United States)

Císarová, Klára; Lamr, Marián; Vitvarová, Jana

2015-01-01

The paper describes an e-learning system called Advanced Learning Space that was developed at the Technical University of Liberec. The system provides a personalized virtual work space and promotes communication among students and their teachers. The core of the system is a module that can be used to automatically record, store and playback…

Geometry planning and image registration in magnetic particle imaging using bimodal fiducial markers

International Nuclear Information System (INIS)

Werner, F.; Hofmann, M.; Them, K.; Knopp, T.; Jung, C.; Salamon, J.; Kaul, M. G.; Mummert, T.; Adam, G.; Ittrich, H.; Werner, R.; Säring, D.; Weber, O. M.

2016-01-01

Purpose: Magnetic particle imaging (MPI) is a quantitative imaging modality that allows the distribution of superparamagnetic nanoparticles to be visualized. Compared to other imaging techniques like x-ray radiography, computed tomography (CT), and magnetic resonance imaging (MRI), MPI only provides a signal from the administered tracer, but no additional morphological information, which complicates geometry planning and the interpretation of MP images. The purpose of the authors’ study was to develop bimodal fiducial markers that can be visualized by MPI and MRI in order to create MP–MR fusion images. Methods: A certain arrangement of three bimodal fiducial markers was developed and used in a combined MRI/MPI phantom and also during in vivo experiments in order to investigate its suitability for geometry planning and image fusion. An algorithm for automated marker extraction in both MR and MP images and rigid registration was established. Results: The developed bimodal fiducial markers can be visualized by MRI and MPI and allow for geometry planning as well as automated registration and fusion of MR–MP images. Conclusions: To date, exact positioning of the object to be imaged within the field of view (FOV) and the assignment of reconstructed MPI signals to corresponding morphological regions has been difficult. The developed bimodal fiducial markers and the automated image registration algorithm help to overcome these difficulties.

Geometry planning and image registration in magnetic particle imaging using bimodal fiducial markers

Energy Technology Data Exchange (ETDEWEB)

Werner, F., E-mail: f.werner@uke.de; Hofmann, M.; Them, K.; Knopp, T. [Section for Biomedical Imaging, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany and Institute for Biomedical Imaging, Hamburg University of Technology, Hamburg 21073 (Germany); Jung, C.; Salamon, J.; Kaul, M. G.; Mummert, T.; Adam, G.; Ittrich, H. [Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Hamburg 20246 (Germany); Werner, R.; Säring, D. [Institute for Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg 20246 (Germany); Weber, O. M. [Philips Medical Systems DMC GmbH, Hamburg 22335 (Germany)

2016-06-15

Purpose: Magnetic particle imaging (MPI) is a quantitative imaging modality that allows the distribution of superparamagnetic nanoparticles to be visualized. Compared to other imaging techniques like x-ray radiography, computed tomography (CT), and magnetic resonance imaging (MRI), MPI only provides a signal from the administered tracer, but no additional morphological information, which complicates geometry planning and the interpretation of MP images. The purpose of the authors’ study was to develop bimodal fiducial markers that can be visualized by MPI and MRI in order to create MP–MR fusion images. Methods: A certain arrangement of three bimodal fiducial markers was developed and used in a combined MRI/MPI phantom and also during in vivo experiments in order to investigate its suitability for geometry planning and image fusion. An algorithm for automated marker extraction in both MR and MP images and rigid registration was established. Results: The developed bimodal fiducial markers can be visualized by MRI and MPI and allow for geometry planning as well as automated registration and fusion of MR–MP images. Conclusions: To date, exact positioning of the object to be imaged within the field of view (FOV) and the assignment of reconstructed MPI signals to corresponding morphological regions has been difficult. The developed bimodal fiducial markers and the automated image registration algorithm help to overcome these difficulties.

Pluto/Charon exploration utilizing a bi-modal PBR nuclear propulsion/power system

Science.gov (United States)

Venetoklis, Peter S.

1995-01-01

The paper describes a Pluto/Charon orbiter utilizing a bi-modal nuclear propulsion and power system based on the Particle Bed Reactor. The orbiter is sized for launch to Nuclear-Safe orbit atop a Titan IV or equivalent launch veicle. The bi-modal system provides thermal propulsion for Earth orbital departure and Pluto orbital capture, and 10 kWe of electric power for payload functions and for in-system maneuvering with ion thrusters. Ion thrusters are used to perform inclination changes about Pluto, a transfer from low Pluto orbit to low Charon orbit, and inclination changes about charon. A nominal payload can be deliverd in as little as 15 years, 1000 kg in 17 years, and close to 2000 kg in 20 years. Scientific return is enormously aided by the availability of up to 10 kWe, due to greater data transfer rates and more/better instruments. The bi-modal system can provide power at Pluto/Charon for 10 or more years, enabling an extremely robust, scientifically rewarding, and cost-effective exploration mission.

Advancing automation and robotics technology for the space station and for the US economy

Science.gov (United States)

Nunamaker, Robert

1988-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on the Space Station. This material was documented in the initial report (NASA Technical Memo 87566). A further requirement of the law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the sixth in a series of progress updates and covers the period between October 1, 1987 and March 1, 1988. NASA has accepted the basic recommendations of ATAC for its Space Station efforts. ATAC and NASA agree that the thrust of Congress is to build an advanced automation and robotics technology base that will support an evolutionary Space Station program and serve as a highly visible stimulator affecting the U.S. long-term economy. The progress report identifies the work of NASA and the Space Station study contractors, research in progress, and issues connected with the advancement of automation and robotics technology on the Space Station.

Future mission opportunities and requirements for advanced space photovoltaic energy conversion technology

Science.gov (United States)

Flood, Dennis J.

1990-01-01

The variety of potential future missions under consideration by NASA will impose a broad range of requirements on space solar arrays, and mandates the development of new solar cells which can offer a wide range of capabilities to mission planners. Major advances in performance have recently been achieved at several laboratories in a variety of solar cell types. Many of those recent advances are reviewed, the areas are examined where possible improvements are yet to be made, and the requirements are discussed that must be met by advanced solar cell if they are to be used in space. The solar cells of interest include single and multiple junction cells which are fabricated from single crystal, polycrystalline and amorphous materials. Single crystal cells on foreign substrates, thin film single crystal cells on superstrates, and multiple junction cells which are either mechanically stacked, monolithically grown, or hybrid structures incorporating both techniques are discussed. Advanced concentrator array technology for space applications is described, and the status of thin film, flexible solar array blanket technology is reported.

Near-Infrared Squaraine Dye Encapsulated Micelles for in Vivo Fluorescence and Photoacoustic Bimodal Imaging.

Science.gov (United States)

Sreejith, Sivaramapanicker; Joseph, James; Lin, Manjing; Menon, Nishanth Venugopal; Borah, Parijat; Ng, Hao Jun; Loong, Yun Xian; Kang, Yuejun; Yu, Sidney Wing-Kwong; Zhao, Yanli

2015-06-23

Combined near-infrared (NIR) fluorescence and photoacoustic imaging techniques present promising capabilities for noninvasive visualization of biological structures. Development of bimodal noninvasive optical imaging approaches by combining NIR fluorescence and photoacoustic tomography demands suitable NIR-active exogenous contrast agents. If the aggregation and photobleaching are prevented, squaraine dyes are ideal candidates for fluorescence and photoacoustic imaging. Herein, we report rational selection, preparation, and micelle encapsulation of an NIR-absorbing squaraine dye (D1) for in vivo fluorescence and photoacoustic bimodal imaging. D1 was encapsulated inside micelles constructed from a biocompatible nonionic surfactant (Pluoronic F-127) to obtain D1-encapsulated micelles (D1(micelle)) in aqueous conditions. The micelle encapsulation retains both the photophysical features and chemical stability of D1. D1(micelle) exhibits high photostability and low cytotoxicity in biological conditions. Unique properties of D1(micelle) in the NIR window of 800-900 nm enable the development of a squaraine-based exogenous contrast agent for fluorescence and photoacoustic bimodal imaging above 820 nm. In vivo imaging using D1(micelle), as demonstrated by fluorescence and photoacoustic tomography experiments in live mice, shows contrast-enhanced deep tissue imaging capability. The usage of D1(micelle) proven by preclinical experiments in rodents reveals its excellent applicability for NIR fluorescence and photoacoustic bimodal imaging.

Penetration in bimodal, polydisperse granular material

KAUST Repository

Kouraytem, Nadia; Thoroddsen, Sigurdur T; Marston, J. O.

2016-01-01

We investigate the impact penetration of spheres into granular media which are compositions of two discrete size ranges, thus creating a polydisperse bimodal material. We examine the penetration depth as a function of the composition (volume fractions of the respective sizes) and impact speed. Penetration depths were found to vary between delta = 0.5D(0) and delta = 7D(0), which, for mono-modal media only, could be correlated in terms of the total drop height, H = h + delta, as in previous studies, by incorporating correction factors for the packing fraction. Bimodal data can only be collapsed by deriving a critical packing fraction for each mass fraction. The data for the mixed grains exhibit a surprising lubricating effect, which was most significant when the finest grains [d(s) similar to O(30) mu m] were added to the larger particles [d(l) similar to O(200 - 500) mu m], with a size ratio, epsilon = d(l)/d(s), larger than 3 and mass fractions over 25%, despite the increased packing fraction. We postulate that the small grains get between the large grains and reduce their intergrain friction, only when their mass fraction is sufficiently large to prevent them from simply rattling in the voids between the large particles. This is supported by our experimental observations of the largest lubrication effect produced by adding small glass beads to a bed of large sand particles with rough surfaces.

Penetration in bimodal, polydisperse granular material

KAUST Repository

Kouraytem, N.

2016-11-07

We investigate the impact penetration of spheres into granular media which are compositions of two discrete size ranges, thus creating a polydisperse bimodal material. We examine the penetration depth as a function of the composition (volume fractions of the respective sizes) and impact speed. Penetration depths were found to vary between delta = 0.5D(0) and delta = 7D(0), which, for mono-modal media only, could be correlated in terms of the total drop height, H = h + delta, as in previous studies, by incorporating correction factors for the packing fraction. Bimodal data can only be collapsed by deriving a critical packing fraction for each mass fraction. The data for the mixed grains exhibit a surprising lubricating effect, which was most significant when the finest grains [d(s) similar to O(30) mu m] were added to the larger particles [d(l) similar to O(200 - 500) mu m], with a size ratio, epsilon = d(l)/d(s), larger than 3 and mass fractions over 25%, despite the increased packing fraction. We postulate that the small grains get between the large grains and reduce their intergrain friction, only when their mass fraction is sufficiently large to prevent them from simply rattling in the voids between the large particles. This is supported by our experimental observations of the largest lubrication effect produced by adding small glass beads to a bed of large sand particles with rough surfaces.

Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

Science.gov (United States)

Hueter, Uwe; Turner, James

1999-01-01

NASA's Office of Aero-Space Technology (OAST) has established three major goals, referred to as, "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala. focuses on future space transportation technologies Under the "Access to Space" pillar. The Core Technologies Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. One of the main activities over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the decision to determine the path this country will take for Space Shuttle and RLV. This year, additional technology efforts in the reusable technologies will be awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion.

Advanced Space Surface Systems Operations

Science.gov (United States)

Huffaker, Zachary Lynn; Mueller, Robert P.

2014-01-01

The importance of advanced surface systems is becoming increasingly relevant in the modern age of space technology. Specifically, projects pursued by the Granular Mechanics and Regolith Operations (GMRO) Lab are unparalleled in the field of planetary resourcefulness. This internship opportunity involved projects that support properly utilizing natural resources from other celestial bodies. Beginning with the tele-robotic workstation, mechanical upgrades were necessary to consider for specific portions of the workstation consoles and successfully designed in concept. This would provide more means for innovation and creativity concerning advanced robotic operations. Project RASSOR is a regolith excavator robot whose primary objective is to mine, store, and dump regolith efficiently on other planetary surfaces. Mechanical adjustments were made to improve this robot's functionality, although there were some minor system changes left to perform before the opportunity ended. On the topic of excavator robots, the notes taken by the GMRO staff during the 2013 and 2014 Robotic Mining Competitions were effectively organized and analyzed for logistical purposes. Lessons learned from these annual competitions at Kennedy Space Center are greatly influential to the GMRO engineers and roboticists. Another project that GMRO staff support is Project Morpheus. Support for this project included successfully producing mathematical models of the eroded landing pad surface for the vertical testbed vehicle to predict a timeline for pad reparation. And finally, the last project this opportunity made contribution to was Project Neo, a project exterior to GMRO Lab projects, which focuses on rocket propulsion systems. Additions were successfully installed to the support structure of an original vertical testbed rocket engine, thus making progress towards futuristic test firings in which data will be analyzed by students affiliated with Rocket University. Each project will be explained in

The Development of Bimodal Bilingualism: Implications for Linguistic Theory.

Science.gov (United States)

Lillo-Martin, Diane; de Quadros, Ronice Müller; Pichler, Deborah Chen

2016-01-01

A wide range of linguistic phenomena contribute to our understanding of the architecture of the human linguistic system. In this paper we present a proposal dubbed Language Synthesis to capture bilingual phenomena including code-switching and 'transfer' as automatic consequences of the addition of a second language, using basic concepts of Minimalism and Distributed Morphology. Bimodal bilinguals, who use a sign language and a spoken language, provide a new type of evidence regarding possible bilingual phenomena, namely code-blending, the simultaneous production of (aspects of) a message in both speech and sign. We argue that code-blending also follows naturally once a second articulatory interface is added to the model. Several different types of code-blending are discussed in connection to the predictions of the Synthesis model. Our primary data come from children developing as bimodal bilinguals, but our proposal is intended to capture a wide range of bilingual effects across any language pair.

Polyethyleneimine-loaded bimodal porous silica as low-cost and high-capacity sorbent for CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Witoon, Thongthai, E-mail: fengttwi@ku.ac.th [National Center of Excellence for Petroleum, Petrochemicals and Advance Material, Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Center for Advanced Studies in Nanotechnology and Its Applications in Chemical Food and Agricultural Industries, Kasetsart University, Bangkok 10900 (Thailand)

2012-11-15

In this work, bimodal (meso-macro) porous silicas with different mesopore diameters synthesized by using rice husk ash as a low-cost silica source and chitosan as a natural template were used as a polyethyleneimine (PEI) support for CO{sub 2} capture. Unimodal porous silica supports with equivalent mesopore diameters to bimodal porous silica supports have been prepared for purpose of comparison. Effects of different PEI contents (10, 20, 30, 40 and 50 wt%) on CO{sub 2} sorption capacity have been systematically investigated. The porous silica supports and the PEI-loaded porous silica supports were characterized by N{sub 2}-sorption analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analysis. CO{sub 2} sorption measurements of all PEI-loaded porous silica supports were performed at different adsorption temperatures (60, 75, 85, 90, 95 and 105 Degree-Sign C). At low PEI contents (10-20 wt%), the CO{sub 2} sorption of all adsorbents was found to decrease as a function of adsorption temperature, which was a characteristic of a thermodynamically-controlled regime. A transition from the thermodynamically-controlled regime to a kinetically-controlled regime was found when the PEI content was increased up to 30 wt% for PEI-loaded unimodal porous silicas and 40 wt% for PEI-loaded bimodal porous silicas. At high PEI contents (40-50 wt%), the CO{sub 2} capturing efficiency of the PEI-loaded bimodal porous silicas was found to be considerably greater than that of the PEI-loaded unimodal porous silicas, indicating that most of the amine groups of PEI molecules loaded on the unimodal porous silica supports was useless, and thus the appeared macroporosity of the bimodal porous silica supports could provide a higher effective amine density to adsorb CO{sub 2}. Highlights: Black-Right-Pointing-Pointer PEI-impregnated bimodal porous silica as low-cost sorbent for CO{sub 2} capture. Black-Right-Pointing-Pointer Macropores enhances

Microstructure, plastic deformation and strengthening mechanisms of an Al–Mg–Si alloy with a bimodal grain structure

International Nuclear Information System (INIS)

Shakoori Oskooie, M.; Asgharzadeh, H.; Kim, H.S.

2015-01-01

Highlights: • Al6063 with bimodal grain structures was fabricated by a powder metallurgy route. • The bimodal alloys showed a reasonable ductility together with a high strength. • Grain boundary strengthening was reduced at higher fraction of coarse grains. • The enhanced tensile ductility was attributed to crack blunting and delamination. - Abstract: Al6063 alloys with bimodal grain size distributions comprised of ultrafine-grained (UFG) and coarse-grained (CG) regions were produced via mechanical milling followed by hot extrusion. High-energy planetary ball milling for 22.5 h with a rotational speed of 350 rpm was employed for the synthesis of nanocrystalline Al6063 powders. The as-milled Al6063 powders were mixed with 15, 30, and 45 vol.% of the unmilled powders and then the powder mixtures were consolidated via extrusion at 450 °C with an extrusion ratio of 9:1. The microstructure of the bimodal extrudates was investigated using optical microscope, transmission electron microscope (TEM) and field emission scanning electron microscope equipped with an electron backscattered diffraction (EBSD) detector. The deformation behavior was investigated by means of uniaxial tensile tests. The bimodal Al6063 exhibited balanced mechanical properties, including high yield stress and ultimate tensile strength resulting from the UFG regions together with reasonable ductility attained from the CG areas. The fracture surfaces demonstrated a ductile fracture mode, in which the dimple size was correlated with the grain structure. The strengthening mechanisms are discussed based on the dislocation models and the functions of the CGs in the deformation behavior and ductility enhancement of bimodal Al6063 are explored

Flexible transparent conducting films with embedded silver networks composed of bimodal-sized nanoparticles for heater application

Science.gov (United States)

Park, Ji Sun; Song, Yookyung; Park, Daseul; Kim, Yeon-Won; Kim, Yoon Jin

2018-06-01

A facile one-pot synthetic method for preparing the Ag nanoparticle inks with a bimodal size distribution was newly devised and they were successfully employed as a conducting filler to form the metal-mesh type transparent conducting electrodes on the flexible substrate. Bimodal-sized Ag nanoparticles were synthesized through the polyol process, and their size variation was occurred via finely tuned composition ratio between Ag+ ions and polymeric capping agents. The prepared bimodal-sized Ag nanoparticles exhibited the form of well-dispersed Ag nanoparticle inks without adding any dispersants and dispersion process. By filling the patterned micro-channels engraved on the flexible polymer substrate using a bimodal-sized Ag nanoparticle ink, a metal-mesh type transparent electrode (transmittance: 90% at 550 nm, haze: 1.5, area: 8 × 8 cm2) was fabricated. By applying DC voltage to the mesh type electrode, a flexible transparent joule heater was successfully achieved with a performance of 4.5 °C s‑1 heat-up rate at a low input power density.

Shielding considerations for advanced space nuclear reactor systems

International Nuclear Information System (INIS)

Angelo, J.P. Jr.; Buden, D.

1982-01-01

To meet the anticipated future space power needs, the Los Alamos National Laboratory is developing components for a compact, 100 kW/sub e/-class heat pipe nuclear reactor. The reactor uses uranium dioxide (UO 2 ) as its fuel, and is designed to operate around 1500 k. Heat pipes are used to remove thermal energy from the core without the use of pumps or compressors. The reactor heat pipes transfer mal energy to thermoelectric conversion elements that are advanced versions of the converters used on the enormously successful Voyager missions to the outer planets. Advanced versions of this heat pipe reactor could also be used to provide megawatt-level power plants. The paper reviews the status of this advanced heat pipe reactor and explores the radiation environments and shielding requirements for representative manned and unmanned applications

Invited Review Article: Advanced light microscopy for biological space research

Science.gov (United States)

De Vos, Winnok H.; Beghuin, Didier; Schwarz, Christian J.; Jones, David B.; van Loon, Jack J. W. A.; Bereiter-Hahn, Juergen; Stelzer, Ernst H. K.

2014-10-01

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as ionizing radiation and microgravity at the cellular and tissue level demands adequate visualization technology. Advanced light microscopy (ALM) is the leading tool for non-destructive structural and functional investigation of static as well as dynamic biological systems. In recent years, technological developments and advances in photochemistry and genetic engineering have boosted all aspects of resolution, readout and throughput, rendering ALM ideally suited for biological space research. While various microscopy-based studies have addressed cellular response to space-related environmental stressors, biological endpoints have typically been determined only after the mission, leaving an experimental gap that is prone to bias results. An on-board, real-time microscopical monitoring device can bridge this gap. Breadboards and even fully operational microscope setups have been conceived, but they need to be rendered more compact and versatile. Most importantly, they must allow addressing the impact of gravity, or the lack thereof, on physiologically relevant biological systems in space and in ground-based simulations. In order to delineate the essential functionalities for such a system, we have reviewed the pending questions in space science, the relevant biological model systems, and the state-of-the art in ALM. Based on a rigorous trade-off, in which we recognize the relevance of multi-cellular systems and the cellular microenvironment, we propose a compact, but flexible concept for space-related cell biological research that is based on light sheet microscopy.

Invited Review Article: Advanced light microscopy for biological space research

International Nuclear Information System (INIS)

De Vos, Winnok H.; Beghuin, Didier; Schwarz, Christian J.; Jones, David B.; Loon, Jack J. W. A. van; Bereiter-Hahn, Juergen; Stelzer, Ernst H. K.

2014-01-01

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as ionizing radiation and microgravity at the cellular and tissue level demands adequate visualization technology. Advanced light microscopy (ALM) is the leading tool for non-destructive structural and functional investigation of static as well as dynamic biological systems. In recent years, technological developments and advances in photochemistry and genetic engineering have boosted all aspects of resolution, readout and throughput, rendering ALM ideally suited for biological space research. While various microscopy-based studies have addressed cellular response to space-related environmental stressors, biological endpoints have typically been determined only after the mission, leaving an experimental gap that is prone to bias results. An on-board, real-time microscopical monitoring device can bridge this gap. Breadboards and even fully operational microscope setups have been conceived, but they need to be rendered more compact and versatile. Most importantly, they must allow addressing the impact of gravity, or the lack thereof, on physiologically relevant biological systems in space and in ground-based simulations. In order to delineate the essential functionalities for such a system, we have reviewed the pending questions in space science, the relevant biological model systems, and the state-of-the art in ALM. Based on a rigorous trade-off, in which we recognize the relevance of multi-cellular systems and the cellular microenvironment, we propose a compact, but flexible concept for space-related cell biological research that is based on light sheet microscopy

Invited Review Article: Advanced light microscopy for biological space research

Energy Technology Data Exchange (ETDEWEB)

De Vos, Winnok H., E-mail: winnok.devos@uantwerpen.be [Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp (Belgium); Cell Systems and Imaging Research Group, Department of Molecular Biotechnology, Ghent University, Ghent (Belgium); Beghuin, Didier [Lambda-X, Nivelles (Belgium); Schwarz, Christian J. [European Space Agency (ESA), ESTEC, TEC-MMG, Noordwijk (Netherlands); Jones, David B. [Institute for Experimental Orthopaedics and Biomechanics, Philipps University, Marburg (Germany); Loon, Jack J. W. A. van [Department of Oral and Maxillofacial Surgery/Oral Pathology, VU University Medical Center and Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, Amsterdam (Netherlands); Bereiter-Hahn, Juergen; Stelzer, Ernst H. K. [Physical Biology, BMLS (FB15, IZN), Goethe University, Frankfurt am Main (Germany)

2014-10-15

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as ionizing radiation and microgravity at the cellular and tissue level demands adequate visualization technology. Advanced light microscopy (ALM) is the leading tool for non-destructive structural and functional investigation of static as well as dynamic biological systems. In recent years, technological developments and advances in photochemistry and genetic engineering have boosted all aspects of resolution, readout and throughput, rendering ALM ideally suited for biological space research. While various microscopy-based studies have addressed cellular response to space-related environmental stressors, biological endpoints have typically been determined only after the mission, leaving an experimental gap that is prone to bias results. An on-board, real-time microscopical monitoring device can bridge this gap. Breadboards and even fully operational microscope setups have been conceived, but they need to be rendered more compact and versatile. Most importantly, they must allow addressing the impact of gravity, or the lack thereof, on physiologically relevant biological systems in space and in ground-based simulations. In order to delineate the essential functionalities for such a system, we have reviewed the pending questions in space science, the relevant biological model systems, and the state-of-the art in ALM. Based on a rigorous trade-off, in which we recognize the relevance of multi-cellular systems and the cellular microenvironment, we propose a compact, but flexible concept for space-related cell biological research that is based on light sheet microscopy.

Does bimodal stimulus presentation increase ERP components usable in BCIs?

NARCIS (Netherlands)

Thurlings, M.E.; Brouwer, A.M.; Erp, J.B.F. van; Blankertz, B.; Werkhoven, P.J.

2012-01-01

Event-related potential (ERP)-based brain–computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain

A bimodal flexible distribution for lifetime data

OpenAIRE

Ramires, Thiago G.; Ortega, Edwin M. M.; Cordeiro, Gauss M.; Hens, Niel

2016-01-01

A four-parameter extended bimodal lifetime model called the exponentiated log-sinh Cauchy distribution is proposed. It extends the log-sinh Cauchy and folded Cauchy distributions. We derive some of its mathematical properties including explicit expressions for the ordinary moments and generating and quantile functions. The method of maximum likelihood is used to estimate the model parameters. We implement the fit of the model in the GAMLSS package and provide the codes. The flexibility of the...

Stellar Rotation with Kepler and Gaia: Evidence for a Bimodal Star Formation History

Science.gov (United States)

Davenport, James

2018-01-01

Kepler stars with rotation periods measured via starspot modulations in their light curves have been matched against the astrometric data from Gaia Data Release 1. A total of 1,299 bright rotating stars were recovered, most with temperatures hotter than 5000 K. From these, 894 were selected as being near the main sequence. These main sequence stars show a bimodality in their rotation period distribution, centered around a ~600 Myr rotation-isochrone. This feature matches the bimodal period distribution found in cooler stars with Kepler, but was previously undetected for solar-type stars due to sample contamination by subgiant and binary stars. A tenuous connection between the rotation period and total proper motion is found, suggesting the period bimodality is due to the age distribution of stars within 300pc of the Sun, rather than a phase of rapid angular momentum loss. I will discuss how the combination of Kepler/K2/TESS with Gaia will enable us to map the star formation history of our galactic neighborhood.

The role of continuous low-frequency harmonicity cues for interrupted speech perception in bimodal hearing.

Science.gov (United States)

Oh, Soo Hee; Donaldson, Gail S; Kong, Ying-Yee

2016-04-01

Low-frequency acoustic cues have been shown to enhance speech perception by cochlear-implant users, particularly when target speech occurs in a competing background. The present study examined the extent to which a continuous representation of low-frequency harmonicity cues contributes to bimodal benefit in simulated bimodal listeners. Experiment 1 examined the benefit of restoring a continuous temporal envelope to the low-frequency ear while the vocoder ear received a temporally interrupted stimulus. Experiment 2 examined the effect of providing continuous harmonicity cues in the low-frequency ear as compared to restoring a continuous temporal envelope in the vocoder ear. Findings indicate that bimodal benefit for temporally interrupted speech increases when continuity is restored to either or both ears. The primary benefit appears to stem from the continuous temporal envelope in the low-frequency region providing additional phonetic cues related to manner and F1 frequency; a secondary contribution is provided by low-frequency harmonicity cues when a continuous representation of the temporal envelope is present in the low-frequency, or both ears. The continuous temporal envelope and harmonicity cues of low-frequency speech are thought to support bimodal benefit by facilitating identification of word and syllable boundaries, and by restoring partial phonetic cues that occur during gaps in the temporally interrupted stimulus.

NONLINEAR COLOR-METALLICITY RELATIONS OF GLOBULAR CLUSTERS. II. A TEST ON THE NONLINEARITY SCENARIO FOR COLOR BIMODALITY USING THE u-BAND COLORS: THE CASE OF M87 (NGC 4486)

International Nuclear Information System (INIS)

Yoon, Suk-Jin; Lee, Sang-Yoon; Kim, Hak-Sub; Cho, Jaeil; Chung, Chul; Sohn, Sangmo T.; Blakeslee, John P.

2011-01-01

The optical color distributions of globular clusters (GCs) in most large elliptical galaxies are bimodal. Based on the assumed linear relationship between GC colors and their metallicities, the bimodality has been taken as evidence of two GC subsystems with different metallicities in each galaxy and has led to a number of theories in the context of galaxy formation. More recent observations and modeling of GCs, however, suggests that the color-metallicity relations (CMRs) are inflected, and thus colors likely trace metallicities in a nonlinear manner. The nonlinearity could produce bimodal color distributions from a broad underlying metallicity spread, even if it is unimodal. Despite the far-reaching implications, whether CMRs are nonlinear and whether the nonlinearity indeed causes the color bimodality are still open questions. Given that the spectroscopic refinement of CMRs is still very challenging, we here propose a new photometric technique to probe the possible nonlinear nature of CMRs. In essence, a color distribution of GCs is a 'projected' distribution of their metallicities. Since the form of CMRs hinges on which color is used, the shape of color distributions varies depending significantly on the colors. Among other optical colors, the u-band related colors (e.g., u – g and u – z) are theoretically predicted to exhibit significantly less inflected CMRs than other preferred CMRs (e.g., for g – z). As a case study, we performed the Hubble Space Telescope (HST)/WFPC2 archival u-band photometry for the M87 (NGC 4486) GC system with confirmed color bimodality. We show that the u-band color distributions are significantly different from that of g – z and consistent with our model predictions. With more u-band measurements, this method will support or rule out the nonlinear CMR scenario for the origin of GC color bimodality with high confidence. The HST/WFC3 observations in F336W for nearby large elliptical galaxies are highly anticipated in this regard.

Advancing automation and robotics technology for the Space Station Freedom and for the U.S. economy

Science.gov (United States)

1993-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on Space Station Freedom. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the sixteenth in a series of progress updates and covers the period between 15 Sep. 1992 - 16 Mar. 1993. The report describes the progress made by Levels 1, 2, and 3 of the Space Station Freedom in developing and applying advanced automation and robotics technology. Emphasis was placed upon the Space Station Freedom Program responses to specific recommendations made in ATAC Progress Report 15; and includes a status review of Space Station Freedom Launch Processing facilities at Kennedy Space Center. Assessments are presented for these and other areas as they apply to the advancement of automation and robotics technology for Space Station Freedom.

Emotional Intensity Modulates the Integration of Bimodal Angry Expressions: ERP Evidence

Directory of Open Access Journals (Sweden)

Zhihui Pan

2017-06-01

Full Text Available Integration of information from face and voice plays a central role in social interactions. The present study investigated the modulation of emotional intensity on the integration of facial-vocal emotional cues by recording EEG for participants while they were performing emotion identification task on facial, vocal, and bimodal angry expressions varying in emotional intensity. Behavioral results showed the rates of anger and reaction speed increased as emotional intensity across modalities. Critically, the P2 amplitudes were larger for bimodal expressions than for the sum of facial and vocal expressions for low emotional intensity stimuli, but not for middle and high emotional intensity stimuli. These findings suggested that emotional intensity modulates the integration of facial-vocal angry expressions, following the principle of Inverse Effectiveness (IE in multimodal sensory integration.

Expert systems and advanced automation for space missions operations

Science.gov (United States)

Durrani, Sajjad H.; Perkins, Dorothy C.; Carlton, P. Douglas

1990-01-01

Increased complexity of space missions during the 1980s led to the introduction of expert systems and advanced automation techniques in mission operations. This paper describes several technologies in operational use or under development at the National Aeronautics and Space Administration's Goddard Space Flight Center. Several expert systems are described that diagnose faults, analyze spacecraft operations and onboard subsystem performance (in conjunction with neural networks), and perform data quality and data accounting functions. The design of customized user interfaces is discussed, with examples of their application to space missions. Displays, which allow mission operators to see the spacecraft position, orientation, and configuration under a variety of operating conditions, are described. Automated systems for scheduling are discussed, and a testbed that allows tests and demonstrations of the associated architectures, interface protocols, and operations concepts is described. Lessons learned are summarized.

Advanced Space Transportation Concepts and Propulsion Technologies for a New Delivery Paradigm

Science.gov (United States)

Robinson, John W.; McCleskey, Carey M.; Rhodes, Russel E.; Lepsch, Roger A.; Henderson, Edward M.; Joyner, Claude R., III; Levack, Daniel J. H.

2013-01-01

This paper describes Advanced Space Transportation Concepts and Propulsion Technologies for a New Delivery Paradigm. It builds on the work of the previous paper "Approach to an Affordable and Productive Space Transportation System". The scope includes both flight and ground system elements, and focuses on their compatibility and capability to achieve a technical solution that is operationally productive and also affordable. A clear and revolutionary approach, including advanced propulsion systems (advanced LOX rich booster engine concept having independent LOX and fuel cooling systems, thrust augmentation with LOX rich boost and fuel rich operation at altitude), improved vehicle concepts (autogeneous pressurization, turbo alternator for electric power during ascent, hot gases to purge system and keep moisture out), and ground delivery systems, was examined. Previous papers by the authors and other members of the Space Propulsion Synergy Team (SPST) focused on space flight system engineering methods, along with operationally efficient propulsion system concepts and technologies. This paper continues the previous work by exploring the propulsion technology aspects in more depth and how they may enable the vehicle designs from the previous paper. Subsequent papers will explore the vehicle design, the ground support system, and the operations aspects of the new delivery paradigm in greater detail.

Transformation of localized necking of strain space into stress space for advanced high strength steel sheet

Science.gov (United States)

Nakwattanaset, Aeksuwat; Suranuntchai, Surasak

2018-03-01

Normally, Forming Limit Curves (FLCs) can’t explain for shear fracture better than Damage Curve, this article aims to show the experimental of Forming Limit Curve (FLC) for Advanced High Strength Steel (AHSS) sheets grade JAC780Y with the Nakazima forming test and tensile tests of different sample geometries. From these results, the Forming Limit Curve (strain space) was transformed to damage curve (stress space) between plastic strain and stress triaxiality. Therefore, Stress space transformed using by Hill-48 and von-Mises yield function. This article shows that two of these yield criterions can use in the transformation.

Advanced Solid State Lighting for AES Deep Space Hab Project

Science.gov (United States)

Holbert, Eirik

2015-01-01

The advanced Solid State Lighting (SSL) assemblies augmented 2nd generation modules under development for the Advanced Exploration Systems Deep Space Habitat in using color therapy to synchronize crew circadian rhythms. Current RGB LED technology does not produce sufficient brightness to adequately address general lighting in addition to color therapy. The intent is to address both through a mix of white and RGB LEDs designing for fully addressable alertness/relaxation levels as well as more dramatic circadian shifts.

An Overview of Advanced Concepts for Near-Space Systems

Science.gov (United States)

2009-06-30

2005). 39 T. R. Knowles, Levitation of a small carbon by visible light, 12th Annual Advanced Space Propulsion Workshop (2001). 40 http...372, 1948. 45 Woodward, J. and Mahood, T., “Gravity, Inertia, and Quantum Vacuum Zero Point Energy Fields,” Foundations of Physics, Vol. 31, No. 5, pp

A One-year, Short-Stay Crewed Mars Mission Using Bimodal Nuclear Thermal Electric Propulsion (BNTEP) - A Preliminary Assessment

Science.gov (United States)

Burke, Laura A.; Borowski, Stanley K.; McCurdy, David R.; Packard, Thomas W.

2013-01-01

A crewed mission to Mars poses a signi cant challenge in dealing with the physiolog- ical issues that arise with the crew being exposed to a near zero-gravity environment as well as signi cant solar and galactic radiation for such a long duration. While long sur- face stay missions exceeding 500 days are the ultimate goal for human Mars exploration, short round trip, short surface stay missions could be an important intermediate step that would allow NASA to demonstrate technology as well as study the physiological e ects on the crew. However, for a 1-year round trip mission, the outbound and inbound hy- perbolic velocity at Earth and Mars can be very large resulting in a signi cant propellant requirement for a high thrust system like Nuclear Thermal Propulsion (NTP). Similarly, a low thrust Nuclear Electric Propulsion (NEP) system requires high electrical power lev- els (10 megawatts electric (MWe) or more), plus advanced power conversion technology to achieve the lower speci c mass values needed for such a mission. A Bimodal Nuclear Thermal Electric Propulsion (BNTEP) system is examined here that uses three high thrust Bimodal Nuclear Thermal Rocket (BNTR) engines allowing short departure and capture maneuvers. The engines also generate electrical power that drives a low thrust Electric Propulsion (EP) system used for ecient interplanetary transit. This combined system can help reduce the total launch mass, system and operational requirements that would otherwise be required for equivalent NEP or Solar Electric Propulsion (SEP) mission. The BNTEP system is a hybrid propulsion concept where the BNTR reactors operate in two separate modes. During high-thrust mode operation, each BNTR provides 10's of kilo- Newtons of thrust at reasonably high speci c impulse (Isp) of 900 seconds for impulsive trans-planetary injection and orbital insertion maneuvers. When in power generation / EP mode, the BNTR reactors are coupled to a Brayton power conversion system allowing each

Galex Lyman-alpha Emitters: Physical Properties, Luminosity Bimodality, And Morphologies.

Science.gov (United States)

Mallery, Ryan P.

2010-01-01

The Galaxy Evolution Explorer spectroscopic survey has uncovered a large statistically significant sample of Lyman-alpha emitters at z sim0.3. ACS imaging of these sources in the COSMOS and AEGIS deep fields reveals that these Lyman-alpha emitters consist of two distinct galaxy morphologies, face on spiral galaxies and compact starburst/merging systems. The morphology bimodality also results in a bimodal distribution of optical luminosity. A comparison between the UV photometry and MIPS 24 micron detections of these sources indicates that they are bluer, and have less dust extinction than similar star forming galaxies that lack Lyman-alpha detection. Our findings show how the global gas and dust distribution of star forming galaxies inhibits Lyman-alpha emission in star forming galaxies. GALEX is a NASA Small Explorer, launched in April 2003. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the CNES of France and the Korean Ministry of Science and Technology.

Statement of Aaron Cohen, Director, Research and Engineering, Johnson Space Center and Chairman, Space Station Advanced Technology Advisory Committee, National Aeronautics and Space Administration, before the Subcommittee on Science, Technology, and Space, Committee on Commerce, Science, and Transportation, United States Senate

Science.gov (United States)

Cohen, A.

1985-01-01

The activities of NASA's Space Station Advanced Technology Advisory Committee is discussed. Advanced Technology Advisory Committee (ATAC) activities over the last year are reviewed in preparation of the report to Congress on the potential for advancing automation and robotics technology for the space station and for the U.S. economy.

Space station as a vital focus for advancing the technologies of automation and robotics

Science.gov (United States)

Varsi, Giulio; Herman, Daniel H.

1988-01-01

A major guideline for the design of the U.S. Space Station is that the Space Station address a wide variety of functions. These functions include the servicing of unmanned assets in space, the support of commercial labs in space and the efficient management of the Space Station itself; the largest space asset. The technologies of Automation and Robotics have the promise to help in reducing Space Station operating costs and to achieve a highly efficient use of the human in space. The use of advanced automation and artificial intelligence techniques, such as expert systems, in Space Station subsystems for activity planning and failure mode management will enable us to reduce dependency on a mission control center and could ultimately result in breaking the umbilical link from Earth to the Space Station. The application of robotic technologies with advanced perception capability and hierarchical intelligent control to servicing system will enable the servicing of assets either in space or in situ with a high degree of human efficiency. The results of studies leading toward the formulation of an automation and robotics plan for Space Station development are presented.

Advancing automation and robotics technology for the Space Station and for the US economy. Volume 1: Executive overview

Science.gov (United States)

1985-01-01

In response to Public Law 98-371, dated July 18, 1984, the NASA Advanced Technology Advisory Committee has studied automation and robotics for use in the Space Station. The Executive Overview, Volume 1 presents the major findings of the study and recommends to NASA principles for advancing automation and robotics technologies for the benefit of the Space Station and of the U.S. economy in general. As a result of its study, the Advanced Technology Advisory Committee believes that a key element of technology for the Space Station is extensive use of advanced general-purpose automation and robotics. These systems could provide the United States with important new methods of generating and exploiting space knowledge in commercial enterprises and thereby help preserve U.S. leadership in space.

A flat space-time relativistic explanation for the perihelion advance of Mercury

OpenAIRE

Behera, Harihar; Naik, P. C.

2003-01-01

Starting with the flat space-time relativistic versions of Maxwell-Heaviside's toy model vector theory of gravity and introducing the gravitational analogues for the electromagnetic Lienard-Wiechert potentials together with the notion of a gravitational Thomas Precession; the observed anomalous perihelion advance of Mercury's orbit is here explained as a relativistic effect in flat (Minkowski) space-time, unlike Einstein's curved space-time relativistic explanation. In this new explanation fo...

Nuclear spectroscopy in large shell model spaces: recent advances

International Nuclear Information System (INIS)

Kota, V.K.B.

1995-01-01

Three different approaches are now available for carrying out nuclear spectroscopy studies in large shell model spaces and they are: (i) the conventional shell model diagonalization approach but taking into account new advances in computer technology; (ii) the recently introduced Monte Carlo method for the shell model; (iii) the spectral averaging theory, based on central limit theorems, in indefinitely large shell model spaces. The various principles, recent applications and possibilities of these three methods are described and the similarity between the Monte Carlo method and the spectral averaging theory is emphasized. (author). 28 refs., 1 fig., 5 tabs

Advanced Fusion Reactors for Space Propulsion and Power Systems

Energy Technology Data Exchange (ETDEWEB)

Chapman, John J.

2011-06-15

In recent years the methodology proposed for conversion of light elements into energy via fusion has made steady progress. Scientific studies and engineering efforts in advanced fusion systems designs have introduced some new concepts with unique aspects including consideration of Aneutronic fuels. The plant parameters for harnessing aneutronic fusion appear more exigent than those required for the conventional fusion fuel cycle. However aneutronic fusion propulsion plants for Space deployment will ultimately offer the possibility of enhanced performance from nuclear gain as compared to existing ionic engines as well as providing a clean solution to Planetary Protection considerations and requirements. Proton triggered 11Boron fuel (p- 11B) will produce abundant ion kinetic energy for In-Space vectored thrust. Thus energetic alpha particles' exhaust momentum can be used directly to produce high Isp thrust and also offer possibility of power conversion into electricity. p-11B is an advanced fusion plant fuel with well understood reaction kinematics but will require some new conceptual thinking as to the most effective implementation.

Advanced Fusion Reactors for Space Propulsion and Power Systems

Science.gov (United States)

Chapman, John J.

2011-01-01

In recent years the methodology proposed for conversion of light elements into energy via fusion has made steady progress. Scientific studies and engineering efforts in advanced fusion systems designs have introduced some new concepts with unique aspects including consideration of Aneutronic fuels. The plant parameters for harnessing aneutronic fusion appear more exigent than those required for the conventional fusion fuel cycle. However aneutronic fusion propulsion plants for Space deployment will ultimately offer the possibility of enhanced performance from nuclear gain as compared to existing ionic engines as well as providing a clean solution to Planetary Protection considerations and requirements. Proton triggered 11Boron fuel (p- 11B) will produce abundant ion kinetic energy for In-Space vectored thrust. Thus energetic alpha particles "exhaust" momentum can be used directly to produce high ISP thrust and also offer possibility of power conversion into electricity. p- 11B is an advanced fusion plant fuel with well understood reaction kinematics but will require some new conceptual thinking as to the most effective implementation.

Bimodal Networks as Candidates for Electroactive Polymers

DEFF Research Database (Denmark)

Bahrt, Frederikke; Daugaard, Anders Egede; Bejenariu, Anca Gabriela

An alternative network formulation method was adopted in order to obtain a different type of silicone based elastomeric systems - the so-called bimodal networks - using two vinyl-terminated polydimethyl siloxanes (PDMS) of different molecular weight, a labelled crosslinker (3 or 4-functional), an...... themselves between the long chains and show how this leads to unexpectedly good properties for DEAP purposes due both to the low extensibility of the short chains that attach strongly the long chains and to the extensibility of the last ones that retards the rupture process....

Controllability of a Class of Bimodal Discrete-Time Piecewise Linear Systems

NARCIS (Netherlands)

Yurtseven, E.; Camlibel, M.K.; Heemels, W.P.M.H.

2013-01-01

In this paper we will provide algebraic necessary and sufficient conditions for the controllability/reachability/null controllability of a class of bimodal discrete-time piecewise linear systems including several instances of interest that are not covered by existing works which focus primarily on

Space- and time-resolved raman and breakdown spectroscopy: advanced lidar techniques

Science.gov (United States)

Silviu, Gurlui; Marius Mihai, Cazacu; Adrian, Timofte; Oana, Rusu; Georgiana, Bulai; Dimitriu, Dan

2018-04-01

DARLIOES - the advanced LIDAR is based on space- and time-resolved RAMAN and breakdown spectroscopy, to investigate chemical and toxic compounds, their kinetics and physical properties at high temporal (2 ns) and spatial (1 cm) resolution. The high spatial and temporal resolution are needed to resolve a large variety of chemical troposphere compounds, emissions from aircraft, the self-organization space charges induced light phenomena, temperature and humidity profiles, ice nucleation, etc.

Transient bimodality in interacting particle systems

International Nuclear Information System (INIS)

Calderoni, P.; Pellegrinotti, A.; Presutti, E.; Vares, M.E.

1989-01-01

The authors consider a system of spins which have values ± 1 and evolve according to a jump Markov process whose generator is the sum of two generators, one describing a spin-flip Glauber process, the other a Kawasaki (stirring) evolution. It was proven elsewhere that if the Kawasaki dynamics is speeded up by a factor var-epsilon -2 , then, in the limit var-epsilon → 0 (continuum limit), propagation of chaos holds and the local magnetization solves a reaction-diffusion equation. They choose the parameters of the Glauber interaction so that the potential of the reaction term in the reaction-diffusion equation is a double-well potential with quartic maximum at the origin. They assume further that for each var-epsilon the system is in a finite interval of Z with var-epsilon -1 sites and periodic boundary conditions. They specify the initial measure as the product measure with 0 spin average, thus obtaining, in the continuum limit, a constant magnetic profile equal to 0, which is a stationary unstable solution to the reaction-diffusion equation. They prove that at times of the order var-epsilon -1/2 propagation of chaos does not hold any more and, in the limit as var-epsilon → 0, the state becomes a nontrivial superposition of Bernoulli measures with parameters corresponding to the minima of the reaction potential. The coefficients of such a superposition depend on time (on the scale var-epsilon -1/2 ) and at large times (on this scale) the coefficient of the term corresponding to the initial magnetization vanishes (transient bimodality). This differs from what was observed by De Masi, Presutti, and Vares, who considered a reaction potential with quadratic maximum and no bimodal effect was seen, as predicted by Broggi, Lugiato, and Colombo

Significant Corrosion Resistance in an Ultrafine-Grained Al6063 Alloy with a Bimodal Grain-Size Distribution through a Self-Anodic Protection Mechanism

Directory of Open Access Journals (Sweden)

Mahdieh Shakoori Oskooie

2016-12-01

Full Text Available The bimodal microstructures of Al6063 consisting of 15, 30, and 45 vol. % coarse-grained (CG bands within the ultrafine-grained (UFG matrix were synthesized via blending of high-energy mechanically milled powders with unmilled powders followed by hot powder extrusion. The corrosion behavior of the bimodal specimens was assessed by means of polarization, steady-state cyclic polarization and impedance tests, whereas their microstructural features and corrosion products were examined using optical microscopy (OM, scanning transmission electron microscopy (STEM, field emission scanning electron microscopy (FE-SEM, electron backscattered diffraction (EBSD, energy dispersive spectroscopy (EDS, and X-ray diffraction (XRD techniques. The bimodal Al6063 containing 15 vol. % CG phase exhibits the highest corrosion resistance among the bimodal microstructures and even superior electrochemical behavior compared with the plain UFG and CG materials in the 3.5% NaCl solution. The enhanced corrosion resistance is attributed to the optimum cathode to anode surface area ratio that gives rise to the formation of an effective galvanic couple between CG areas and the UFG matrix. The operational galvanic coupling leads to the domination of a “self-anodic protection system” on bimodal microstructure and consequently forms a uniform thick protective passive layer over it. In contrast, the 45 vol. % CG bimodal specimen shows the least corrosion resistance due to the catastrophic galvanic corrosion in UFG regions. The observed results for UFG Al6063 suggest that metallurgical tailoring of the grain structure in terms of bimodal microstructures leads to simultaneous enhancement in the electrochemical behavior and mechanical properties of passivable alloys that are usually inversely correlated. The mechanism of self-anodic protection for passivable metals with bimodal microstructures is discussed here for the first time.

Acid-base and ion balance in fishes with bimodal respiration.

Science.gov (United States)

Shartau, R B; Brauner, C J

2014-03-01

The evolution of air breathing during the Devonian provided early fishes with bimodal respiration with a stable O2 supply from air. This was, however, probably associated with challenges and trade-offs in terms of acid-base balance and ionoregulation due to reduced gill:water interaction and changes in gill morphology associated with air breathing. While many aspects of acid-base and ionoregulation in air-breathing fishes are similar to water breathers, the specific cellular and molecular mechanisms involved remain largely unstudied. In general, reduced ionic permeability appears to be an important adaptation in the few bimodal fishes investigated but it is not known if this is a general characteristic. The kidney appears to play an important role in minimizing ion loss to the freshwater environment in the few species investigated, and while ion uptake across the gut is probably important, it has been largely unexplored. In general, air breathing in facultative air-breathing fishes is associated with an acid-base disturbance, resulting in an increased partial pressure of arterial CO2 and a reduction in extracellular pH (pHE ); however, several fishes appear to be capable of tightly regulating tissue intracellular pH (pHI ), despite a large sustained reduction in pHE , a trait termed preferential pHI regulation. Further studies are needed to determine whether preferential pHI regulation is a general trait among bimodal fishes and if this confers reduced sensitivity to acid-base disturbances, including those induced by hypercarbia, exhaustive exercise and hypoxia or anoxia. Additionally, elucidating the cellular and molecular mechanisms may yield insight into whether preferential pHI regulation is a trait ultimately associated with the early evolution of air breathing in vertebrates. © 2014 The Fisheries Society of the British Isles.

Deaf Parents of Cochlear-Implanted Children: Beliefs on Bimodal Bilingualism

Science.gov (United States)

Mitchiner, Julie Cantrell

2015-01-01

This study investigated 17 Deaf families in North America with cochlear-implanted children about their attitudes, beliefs, and practices on bimodal bilingualism (defined as using both a visual/manual language and an aural/oral language) in American Sign Language (ASL) and English. A survey and follow-up interviews with 8 families were conducted.…

Neutronics Study of the KANUTER Space Propulsion Reactor

International Nuclear Information System (INIS)

Venneri, Paolo; Nam, Seung Hyun; Kim, Yonghee

2014-01-01

The Korea Advanced Nuclear Thermal Engine Rocket (KANUTER) has been developed at the Korea Advanced Institute of Science and Technology (KAIST). This space propulsion system is unique in that it implements a HEU fuel with a thermal spectrum system. This allows the system to be designed with a minimal amount of fissile material and an incredibly small and light system. This then allows the implementation of the system in a cluster format which enables redundancy and easy scalability for different mission requirements. This combination of low fissile content, compact size, and thermalized spectrum contribute to an interesting and novel behavior of the reactor system. The two codes were both used for the burn up calculations in order to verify their validity while the static calculations and characterization of the core were done principally with MCNPX. The KANUTER space propulsion reactor is in the process of being characterized and improved. Its basic neutronic characteristics have been studied, and its behavior over time has been identified. It has been shown that this reactor will have difficulty operating as hoped in a bimodal configuration where it is able to provide both propulsion and power throughout mission to Mars. The reason for this has been identified as Xe 135 , and it is believed that a possible solution to this issue does exist, either in the form of an appropriately designed neutron spectrum or the building in of sufficient excess reactivity

Neutronics Study of the KANUTER Space Propulsion Reactor

Energy Technology Data Exchange (ETDEWEB)

Venneri, Paolo; Nam, Seung Hyun; Kim, Yonghee [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2014-05-15

The Korea Advanced Nuclear Thermal Engine Rocket (KANUTER) has been developed at the Korea Advanced Institute of Science and Technology (KAIST). This space propulsion system is unique in that it implements a HEU fuel with a thermal spectrum system. This allows the system to be designed with a minimal amount of fissile material and an incredibly small and light system. This then allows the implementation of the system in a cluster format which enables redundancy and easy scalability for different mission requirements. This combination of low fissile content, compact size, and thermalized spectrum contribute to an interesting and novel behavior of the reactor system. The two codes were both used for the burn up calculations in order to verify their validity while the static calculations and characterization of the core were done principally with MCNPX. The KANUTER space propulsion reactor is in the process of being characterized and improved. Its basic neutronic characteristics have been studied, and its behavior over time has been identified. It has been shown that this reactor will have difficulty operating as hoped in a bimodal configuration where it is able to provide both propulsion and power throughout mission to Mars. The reason for this has been identified as Xe{sup 135}, and it is believed that a possible solution to this issue does exist, either in the form of an appropriately designed neutron spectrum or the building in of sufficient excess reactivity.

Multiphase flow modeling of a crude-oil spill site with a bimodal permeability distribution

Science.gov (United States)

Dillard, Leslie A.; Essaid, Hedeff I.; Herkelrath, William N.

1997-01-01

Fluid saturation, particle-size distribution, and porosity measurements were obtained from 269 core samples collected from six boreholes along a 90-m transect at a subregion of a crude-oil spill site, the north pool, near Bemidji, Minnesota. The oil saturation data, collected 11 years after the spill, showed an irregularly shaped oil body that appeared to be affected by sediment spatial variability. The particle-size distribution data were used to estimate the permeability (k) and retention curves for each sample. An additional 344 k estimates were obtained from samples previously collected at the north pool. The 613 k estimates were distributed bimodal lognormally with the two population distributions corresponding to the two predominant lithologies: a coarse glacial outwash deposit and fine-grained interbedded lenses. A two-step geostatistical approach was used to generate a conditioned realization of k representing the bimodal heterogeneity. A cross-sectional multiphase flow model was used to simulate the flow of oil and water in the presence of air along the north pool transect for an 11-year period. The inclusion of a representation of the bimodal aquifer heterogeneity was crucial for reproduction of general features of the observed oil body. If the bimodal heterogeneity was characterized, hysteresis did not have to be incorporated into the model because a hysteretic effect was produced by the sediment spatial variability. By revising the relative permeability functional relation, an improved reproduction of the observed oil saturation distribution was achieved. The inclusion of water table fluctuations in the model did not significantly affect the simulated oil saturation distribution.

Advancing automation and robotics technology for the Space Station Freedom and for the U.S. Economy

Science.gov (United States)

1991-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on Space Station Freedom. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the thirteenth in a series of progress updates and covers the period between 14 Feb. - 15 Aug. 1991. The progress made by Levels 1, 2, and 3 of the Space Station Freedom in developing and applying advanced automation and robotics technology is described. Emphasis was placed upon the Space Station Freedom Program responses to specific recommendations made in ATAC Progress Report 12, and issues of A&R implementation into Ground Mission Operations and A&R enhancement of science productivity. Assessments are presented for these and other areas as they apply to the advancement of automation and robotics technology for Space Station Freedom.

The Centaurus cluster of galaxies. II. The bimodal-velocity structure

International Nuclear Information System (INIS)

Lucey, J.R.; Currie, M.J.; Dickens, R.J.

1985-09-01

This is the second paper in a series that describes an extensive study of the Centaurus cluster of galaxies. The paper concerns the bimodal velocity distribution of the galaxies in the cluster. The likely location of the two main cluster components is discussed. The data strongly favours the hypothesis that the two components lie within the same cluster. (UK)

NERVA-Derived Concept for a Bimodal Nuclear Thermal Rocket

International Nuclear Information System (INIS)

Fusselman, Steven P.; Frye, Patrick E.; Gunn, Stanley V.; Morrison, Calvin Q.; Borowski, Stanley K.

2005-01-01

The Nuclear Thermal Rocket is an enabling technology for human exploration missions. The 'bimodal' NTR (BNTR) provides a novel approach to meeting both propulsion and power requirements of future manned and robotic missions. The purpose of this study was to evaluate tie-tube cooling configurations, NTR performance, Brayton cycle performance, and LOX-Augmented NTR (LANTR) feasibility to arrive at a point of departure BNTR configuration for subsequent system definition

Combining bimodal presentation schemes and buzz groups improves clinical reasoning and learning at morning report.

Science.gov (United States)

Balslev, Thomas; Rasmussen, Astrid Bruun; Skajaa, Torjus; Nielsen, Jens Peter; Muijtjens, Arno; De Grave, Willem; Van Merriënboer, Jeroen

2014-12-11

Abstract Morning reports offer opportunities for intensive work-based learning. In this controlled study, we measured learning processes and outcomes with the report of paediatric emergency room patients. Twelve specialists and 12 residents were randomised into four groups and discussed the same two paediatric cases. The groups differed in their presentation modality (verbal only vs. verbal + text) and the use of buzz groups (with vs. without). The verbal interactions were analysed for clinical reasoning processes. Perceptions of learning and judgment of learning were reported in a questionnaire. Diagnostic accuracy was assessed by a 20-item multiple-choice test. Combined bimodal presentation and buzz groups increased the odds ratio of clinical reasoning to occur in the discussion of cases by a factor of 1.90 (p = 0.013), indicating superior reasoning for buzz groups working with bimodal materials. For specialists, a positive effect of bimodal presentation was found on perceptions of learning (p presentation on diagnostic accuracy was noted in the specialists (p presentation and buzz group discussion of emergency cases improves clinicians' clinical reasoning and learning.

Oncogenic Nras has bimodal effects on stem cells that sustainably increase competitiveness.

Science.gov (United States)

Li, Qing; Bohin, Natacha; Wen, Tiffany; Ng, Victor; Magee, Jeffrey; Chen, Shann-Ching; Shannon, Kevin; Morrison, Sean J

2013-12-05

'Pre-leukaemic' mutations are thought to promote clonal expansion of haematopoietic stem cells (HSCs) by increasing self-renewal and competitiveness; however, mutations that increase HSC proliferation tend to reduce competitiveness and self-renewal potential, raising the question of how a mutant HSC can sustainably outcompete wild-type HSCs. Activating mutations in NRAS are prevalent in human myeloproliferative neoplasms and leukaemia. Here we show that a single allele of oncogenic Nras(G12D) increases HSC proliferation but also increases reconstituting and self-renewal potential upon serial transplantation in irradiated mice, all prior to leukaemia initiation. Nras(G12D) also confers long-term self-renewal potential to multipotent progenitors. To explore the mechanism by which Nras(G12D) promotes HSC proliferation and self-renewal, we assessed cell-cycle kinetics using H2B-GFP label retention and 5-bromodeoxyuridine (BrdU) incorporation. Nras(G12D) had a bimodal effect on HSCs, increasing the frequency with which some HSCs divide and reducing the frequency with which others divide. This mirrored bimodal effects on reconstituting potential, as rarely dividing Nras(G12D) HSCs outcompeted wild-type HSCs, whereas frequently dividing Nras(G12D) HSCs did not. Nras(G12D) caused these effects by promoting STAT5 signalling, inducing different transcriptional responses in different subsets of HSCs. One signal can therefore increase HSC proliferation, competitiveness and self-renewal through bimodal effects on HSC gene expression, cycling and reconstituting potential.

Advanced Thermophotovoltaic Devices for Space Nuclear Power Systems

International Nuclear Information System (INIS)

Wernsman, Bernard; Mahorter, Robert G.; Siergiej, Richard; Link, Samuel D.; Wehrer, Rebecca J.; Belanger, Sean J.; Fourspring, Patrick; Murray, Susan; Newman, Fred; Taylor, Dan; Rahmlow, Tom

2005-01-01

Advanced thermophotovoltaic (TPV) modules capable of producing > 0.3 W/cm2 at an efficiency > 22% while operating at a converter radiator and module temperature of 1228 K and 325 K, respectively, have been made. These advanced TPV modules are projected to produce > 0.9 W/cm2 at an efficiency > 24% while operating at a converter radiator and module temperature of 1373 K and 325 K, respectively. Radioisotope and nuclear (fission) powered space systems utilizing these advanced TPV modules have been evaluated. For a 100 We radioisotope TPV system, systems utilizing as low as 2 general purpose heat source (GPHS) units are feasible, where the specific power for the 2 and 3 GPHS unit systems operating in a 200 K environment is as large as ∼ 16 We/kg and ∼ 14 We/kg, respectively. For a 100 kWe nuclear powered (as was entertained for the thermoelectric SP-100 program) TPV system, the minimum system radiator area and mass is ∼ 640 m2 and ∼ 1150 kg, respectively, for a converter radiator, system radiator and environment temperature of 1373 K, 435 K and 200 K, respectively. Also, for a converter radiator temperature of 1373 K, the converter volume and mass remains less than 0.36 m3 and 640 kg, respectively. Thus, the minimum system radiator + converter (reactor and shield not included) specific mass is ∼ 16 kg/kWe for a converter radiator, system radiator and environment temperature of 1373 K, 425 K and 200 K, respectively. Under this operating condition, the reactor thermal rating is ∼ 1110 kWt. Due to the large radiator area, the added complexity and mission risk needs to be weighed against reducing the reactor thermal rating to determine the feasibility of using TPV for space nuclear (fission) power systems

Noise exposure alters long-term neural firing rates and synchrony in primary auditory and rostral belt cortices following bimodal stimulation.

Science.gov (United States)

Takacs, Joseph D; Forrest, Taylor J; Basura, Gregory J

2017-12-01

We previously demonstrated that bimodal stimulation (spinal trigeminal nucleus [Sp5] paired with best frequency tone) altered neural tone-evoked and spontaneous firing rates (SFRs) in primary auditory cortex (A1) 15 min after pairing in guinea pigs with and without noise-induced tinnitus. Neural responses were enhanced (+10 ms) or suppressed (0 ms) based on the bimodal pairing interval. Here we investigated whether bimodal stimulation leads to long-term (up to 2 h) changes in tone-evoked and SFRs and neural synchrony (correlate of tinnitus) and if the long-term bimodal effects are altered following noise exposure. To obviate the effects of permanent hearing loss on the results, firing rates and neural synchrony were measured three weeks following unilateral (left ear) noise exposure and a temporary threshold shift. Simultaneous extra-cellular single-unit recordings were made from contralateral (to noise) A1 and dorsal rostral belt (RB); an associative auditory cortical region thought to influence A1, before and after bimodal stimulation (pairing intervals of 0 ms; simultaneous Sp5-tone and +10 ms; Sp5 precedes tone). Sixty and 120 min after 0 ms pairing tone-evoked and SFRs were suppressed in sham A1; an effect only preserved 120 min following pairing in noise. Stimulation at +10 ms only affected SFRs 120 min after pairing in sham and noise-exposed A1. Within sham RB, pairing at 0 and +10 ms persistently suppressed tone-evoked and SFRs, while 0 ms pairing in noise markedly enhanced tone-evoked and SFRs up to 2 h. Together, these findings suggest that bimodal stimulation has long-lasting effects in A1 that also extend to the associative RB that is altered by noise and may have persistent implications for how noise damaged brains process multi-sensory information. Moreover, prior to bimodal stimulation, noise damage increased neural synchrony in A1, RB and between A1 and RB neurons. Bimodal stimulation led to persistent changes in neural synchrony in

Pharyngeal Airway Space Changes After Condylar Replacement and Mandibular Advancement Surgery.

Science.gov (United States)

Yuen, Holly; Rossouw, P Emile; Wolford, Larry M; Wang, Hongyue

2018-01-03

The aim of this study was to examine the total volume and cross-sectional areas of the pharyngeal airway after bilateral condylar replacement and mandibular advancement surgery. A total of 137 patients (126 women and 11 men) underwent bilateral temporomandibular joint total joint replacement performed by 1 surgeon. A subsample of 30 patients who underwent condylar replacement and only mandibular advancement were evaluated for impact on the airway. Measurements were taken preoperatively, postoperatively, and at a follow-up 1 year after surgery on cone beam computed tomography scans. InVivoDental 3-dimensional imaging (Anatomage, San Jose, CA) was used to measure airway space regarding total volume (in cubic centimeters); minimum cross-sectional area (in square millimeters); minimum cross sections of the first, second, and third cervical vertebrae; and whether the patient had mandibular retrognathia before surgery. A second operator was used to test for interoperator error. Descriptive and bivariate statistics were computed, and the P value was set at .05. There was a significant increase in all measurements at the follow-up visit compared with the preoperative visit. There were no significant differences between groups based on simultaneous Le Fort I surgery, mandibular retrognathia, and gender. However, there were statistically significant differences in cross sections 1 and 2, as well as minimum cross-sectional area, regarding age. Condylar replacement and mandibular advancement have a significant association with an increase in airway space. The intraclass correlation coefficient showed excellent agreement between interoperator measurements. Patients undergoing bilateral temporomandibular joint replacement and mandibular advancement surgery showed an increase in pharyngeal airway space at a 1-year follow-up. In this study, age was significantly associated with the cross-sectional areas of the airway, with older patients having smaller values. Copyright © 2018

Preparation of mesoporous NiO with a bimodal pore size distribution and application in electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Wang Dengchao; Ni Wenbin; Pang Huan; Lu Qingyi; Huang Zhongjie [Key Laboratory of Analytical Chemistry for Life Science (MOE), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210008 (China); Zhao Jianwei, E-mail: zhaojw@nju.edu.c [Key Laboratory of Analytical Chemistry for Life Science (MOE), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210008 (China)

2010-09-01

Mesoporous nickel oxide with a porous structure exhibiting a bimodal pore size distribution (2.6 and 30.3 nm diameter pores) has been synthesized in this paper. Firstly, a mesoporous precursor of coordination complex Ni{sub 3}(btc){sub 2}.12H{sub 2}O (btc = 1,3,5-benzenrtricarboxylic acid) is synthesized based on the metal-organic coordination mechanism by a hydrothermal method. Then mesoporous NiO with a bimodal size distribution is obtained by calcining the precursor in the air, and characterized by transmission electron microscopy and N{sub 2} adsorption measurements. Such unique multiple porous structure indicates a promising application of the obtained NiO as electrode materials for supercapacitors. The electrochemical behavior has been investigated by cyclic voltammogram, electrochemical impedance spectra and chronopotentiometry in 3 wt.% KOH aqueous electrolyte. The results reveal that the prepared NiO has high-capacitance retention at high scan rate and exhibits excellent cycle-life stability due to its special mesoporous character with bimodal size distribution.

Bimodal microstructure and deformation of cryomilled bulk nanocrystalline Al-7.5Mg alloy

International Nuclear Information System (INIS)

Lee, Z.; Witkin, D.B.; Radmilovic, V.; Lavernia, E.J.; Nutt, S.R.

2005-01-01

The microstructure, mechanical properties and deformation response of bimodal structured nanocrystalline Al-7.5Mg alloy were investigated. Grain refinement was achieved by cryomilling of atomized Al-7.5Mg powders, and then cryomilled nanocrystalline powders blended with 15 and 30% unmilled coarse-grained powders were consolidated by hot isostatic pressing followed by extrusion to produce bulk nanocrystalline alloys. Bimodal bulk nanocrystalline Al-7.5Mg alloys, which were comprised of nanocrystalline grains separated by coarse-grain regions, show balanced mechanical properties of enhanced yield and ultimate strength and reasonable ductility and toughness compared to comparable conventional alloys and nanocrystalline metals. The investigation of tensile and hardness test suggests unusual deformation mechanisms and interactions between ductile coarse-grain bands and nanocrystalline regions

Advancing automation and robotics technology for the Space Station and for the US economy, volume 2

Science.gov (United States)

1985-01-01

In response to Public Law 98-371, dated July 18, 1984, the NASA Advanced Technology Advisory Committee has studied automation and robotics for use in the Space Station. The Technical Report, Volume 2, provides background information on automation and robotics technologies and their potential and documents: the relevant aspects of Space Station design; representative examples of automation and robotics; applications; the state of the technology and advances needed; and considerations for technology transfer to U.S. industry and for space commercialization.

IVth Azores International Advanced School in Space Sciences

CERN Document Server

Santos, Nuno; Monteiro, Mário

2018-01-01

This book presents the proceedings of the IVth Azores International Advanced School in Space Sciences entitled "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds". The school addressed the topics at the forefront of scientific research being conducted in the fields of asteroseismology and exoplanetary science, two fields of modern astrophysics that share many synergies and resources. These proceedings comprise the contributions from 18 invited lecturers, including both monographic presentations and a number of hands-on tutorials.

Advanced Avionics and Processor Systems for a Flexible Space Exploration Architecture

Science.gov (United States)

Keys, Andrew S.; Adams, James H.; Smith, Leigh M.; Johnson, Michael A.; Cressler, John D.

2010-01-01

The Advanced Avionics and Processor Systems (AAPS) project, formerly known as the Radiation Hardened Electronics for Space Environments (RHESE) project, endeavors to develop advanced avionic and processor technologies anticipated to be used by NASA s currently evolving space exploration architectures. The AAPS project is a part of the Exploration Technology Development Program, which funds an entire suite of technologies that are aimed at enabling NASA s ability to explore beyond low earth orbit. NASA s Marshall Space Flight Center (MSFC) manages the AAPS project. AAPS uses a broad-scoped approach to developing avionic and processor systems. Investment areas include advanced electronic designs and technologies capable of providing environmental hardness, reconfigurable computing techniques, software tools for radiation effects assessment, and radiation environment modeling tools. Near-term emphasis within the multiple AAPS tasks focuses on developing prototype components using semiconductor processes and materials (such as Silicon-Germanium (SiGe)) to enhance a device s tolerance to radiation events and low temperature environments. As the SiGe technology will culminate in a delivered prototype this fiscal year, the project emphasis shifts its focus to developing low-power, high efficiency total processor hardening techniques. In addition to processor development, the project endeavors to demonstrate techniques applicable to reconfigurable computing and partially reconfigurable Field Programmable Gate Arrays (FPGAs). This capability enables avionic architectures the ability to develop FPGA-based, radiation tolerant processor boards that can serve in multiple physical locations throughout the spacecraft and perform multiple functions during the course of the mission. The individual tasks that comprise AAPS are diverse, yet united in the common endeavor to develop electronics capable of operating within the harsh environment of space. Specifically, the AAPS tasks for

Bimodal grain-size distribution of Chinese loess, and its palaeoclimatic implications

NARCIS (Netherlands)

Sun, D.G.; Bloemendal, J.; Rea, D.K.; An, Z.S.; Vandenberghe, J.; Lu, H.; Su, R.; Liu, T.S.

2004-01-01

Grain-size analysis indicates that Chinese loess generally shows a bimodal distribution with a coarse and a fine component. The coarse component, comprising the main part of the loess, has pronounced kurtosis and is well sorted, which is interpreted to be the product of dust storms generated by

Resolving the age bimodality of galaxy stellar populations on kpc scales

NARCIS (Netherlands)

Zibetti, Stefano; Gallazzi, Anna R.; Ascasibar, Y.; Charlot, S.; Galbany, L.; García Benito, R.; Kehrig, C.; de Lorenzo-Cáceres, A.; Lyubenova, M.; Marino, R. A.; Márquez, I.; Sánchez, S. F.; van de Ven, G.; Walcher, C. J.; Wisotzki, L.

2017-01-01

Galaxies in the local Universe are known to follow bimodal distributions in the global stellar population properties. We analyse the distribution of the local average stellar population ages of 654 053 sub-galactic regions resolved on ˜1 kpc scales in a volume-corrected sample of 394 galaxies, drawn

Bimodal stimulus timing-dependent plasticity in primary auditory cortex is altered after noise exposure with and without tinnitus.

Science.gov (United States)

Basura, Gregory J; Koehler, Seth D; Shore, Susan E

2015-12-01

Central auditory circuits are influenced by the somatosensory system, a relationship that may underlie tinnitus generation. In the guinea pig dorsal cochlear nucleus (DCN), pairing spinal trigeminal nucleus (Sp5) stimulation with tones at specific intervals and orders facilitated or suppressed subsequent tone-evoked neural responses, reflecting spike timing-dependent plasticity (STDP). Furthermore, after noise-induced tinnitus, bimodal responses in DCN were shifted from Hebbian to anti-Hebbian timing rules with less discrete temporal windows, suggesting a role for bimodal plasticity in tinnitus. Here, we aimed to determine if multisensory STDP principles like those in DCN also exist in primary auditory cortex (A1), and whether they change following noise-induced tinnitus. Tone-evoked and spontaneous neural responses were recorded before and 15 min after bimodal stimulation in which the intervals and orders of auditory-somatosensory stimuli were randomized. Tone-evoked and spontaneous firing rates were influenced by the interval and order of the bimodal stimuli, and in sham-controls Hebbian-like timing rules predominated as was seen in DCN. In noise-exposed animals with and without tinnitus, timing rules shifted away from those found in sham-controls to more anti-Hebbian rules. Only those animals with evidence of tinnitus showed increased spontaneous firing rates, a purported neurophysiological correlate of tinnitus in A1. Together, these findings suggest that bimodal plasticity is also evident in A1 following noise damage and may have implications for tinnitus generation and therapeutic intervention across the central auditory circuit. Copyright © 2015 the American Physiological Society.

Age bimodality in the central region of pseudo-bulges in S0 galaxies

Science.gov (United States)

Mishra, Preetish K.; Barway, Sudhanshu; Wadadekar, Yogesh

2017-11-01

We present evidence for bimodal stellar age distribution of pseudo-bulges of S0 galaxies as probed by the Dn(4000) index. We do not observe any bimodality in age distribution for pseudo-bulges in spiral galaxies. Our sample is flux limited and contains 2067 S0 and 2630 spiral galaxies drawn from the Sloan Digital Sky Survey. We identify pseudo-bulges in S0 and spiral galaxies, based on the position of the bulge on the Kormendy diagram and their central velocity dispersion. Dividing the pseudo-bulges of S0 galaxies into those containing old and young stellar populations, we study the connection between global star formation and pseudo-bulge age on the u - r colour-mass diagram. We find that most old pseudo-bulges are hosted by passive galaxies while majority of young bulges are hosted by galaxies that are star forming. Dividing our sample of S0 galaxies into early-type S0s and S0/a galaxies, we find that old pseudo-bulges are mainly hosted by early-type S0 galaxies while most of the pseudo-bulges in S0/a galaxies are young. We speculate that morphology plays a strong role in quenching of star formation in the disc of these S0 galaxies, which stops the growth of pseudo-bulges, giving rise to old pseudo-bulges and the observed age bimodality.

Bimodality emerges from transport model calculations of heavy ion collisions at intermediate energy

Science.gov (United States)

Mallik, S.; Das Gupta, S.; Chaudhuri, G.

2016-04-01

This work is a continuation of our effort [S. Mallik, S. Das Gupta, and G. Chaudhuri, Phys. Rev. C 91, 034616 (2015)], 10.1103/PhysRevC.91.034616 to examine if signatures of a phase transition can be extracted from transport model calculations of heavy ion collisions at intermediate energy. A signature of first-order phase transition is the appearance of a bimodal distribution in Pm(k ) in finite systems. Here Pm(k ) is the probability that the maximum of the multiplicity distribution occurs at mass number k . Using a well-known model for event generation [Botzmann-Uehling-Uhlenbeck (BUU) plus fluctuation], we study two cases of central collision: mass 40 on mass 40 and mass 120 on mass 120. Bimodality is seen in both the cases. The results are quite similar to those obtained in statistical model calculations. An intriguing feature is seen. We observe that at the energy where bimodality occurs, other phase-transition-like signatures appear. There are breaks in certain first-order derivatives. We then examine if such breaks appear in standard BUU calculations without fluctuations. They do. The implication is interesting. If first-order phase transition occurs, it may be possible to recognize that from ordinary BUU calculations. Probably the reason this has not been seen already is because this aspect was not investigated before.

Bimodal Bilingual Language Development of Hearing Children of Deaf Parents

Science.gov (United States)

Hofmann, Kristin; Chilla, Solveig

2015-01-01

Adopting a bimodal bilingual language acquisition model, this qualitative case study is the first in Germany to investigate the spoken and sign language development of hearing children of deaf adults (codas). The spoken language competence of six codas within the age range of 3;10 to 6;4 is assessed by a series of standardised tests (SETK 3-5,…

Disentangling the climate-driven bimodal growth pattern in coastal and continental Mediterranean pine stands.

Science.gov (United States)

Pacheco, Arturo; Camarero, J Julio; Ribas, Montse; Gazol, Antonio; Gutierrez, E; Carrer, Marco

2018-02-15

Mediterranean climate promotes two distinct growth peaks separated by summer quiescence in trees. This bimodal pattern has been associated to favourable growing conditions during spring and autumn when mild temperatures and soil-water availability enhance cambial activity. Climatic models predict progressive warming and drying for the Mediterranean Basin, which could shorten or shift the spring and autumn growing seasons. We explored this idea by comparing two sites with different Mediterranean climate types (continental/dry and coastal/wet) and studied how climate drives the bimodal growth pattern in Aleppo pine (Pinus halepensis). Specifically we investigated the intra-annual changes in wood anatomy and the corresponding formation of density fluctuations (IADF). Trees on both sites were analyzed by dendrometer monitoring and by developing chronologies of wood anatomical traits. Radial-increment dynamics followed a similar bimodal pattern in both sites but coastal trees showed higher increments during the spring and autumn growth peaks, especially in autumn. The summer rest of cambium activity occurs almost one month earlier in the coastal than in the inland site. Lumen area and cell-wall thickness were significantly smaller in the continental site, while the increment rate of cell-wall thickness during an IADF event was much higher in the coastal pines. The accumulated soil moisture deficit was the main climatic constraint of tracheid enlargement in continental pines. Intra-annual density fluctuations were more frequent in the coastal trees where wood anatomy features recover to average values after such events, meanwhile inland trees presented a much lower recovery rate. Growth bimodality and the formation of density fluctuations were linked, but mild climate of the coastal site allows a longer growing season, which explains why trees in this area showed higher and more variable growth rates. Copyright © 2017 Elsevier B.V. All rights reserved.

'Bi-modal' isoscalar giant dipole strength in 58Ni

International Nuclear Information System (INIS)

Nayak, B.K.; Garg, U.; Hedden, M.; Koss, M.; Li, T.; Liu, Y.; Madhusudhana Rao, P.V.; Zhu, S.; Itoh, M.; Sakaguchi, H.; Takeda, H.; Uchida, M.; Yasuda, Y.; Yosoi, M.; Fujimura, H.; Fujiwara, M.; Hara, K.; Kawabata, T.; Akimune, H.; Harakeh, M.N.

2006-01-01

The strength distribution of the isoscalar giant dipole resonance (ISGDR) in 58 Ni has been obtained over the energy range 10.5-49.5 MeV via extreme forward angle scattering (including 0 deg.) of 386 MeV α particles. We observe a 'bi-modal' E1 strength distribution for the first time in an A<90 nucleus. The observed ISGDR strength distribution is in reasonable agreement with the predictions of a recent RPA calculation

Autonomous vision in space, based on Advanced Stellar Compass platform

DEFF Research Database (Denmark)

Jørgensen, John Leif; Eisenman, Allan R.; Liebe, Carl Christian

1996-01-01

The Ørsted Star Imager, comprises the functionality of an Advanced Stellar Compass (ASC). I.e. it is able to, autonomously solve "the lost in space" attitude problem, as well as determine the attitude with high precision in the matter of seconds. The autonomy makes for a high capability for error......) Complex Object surface tracking (e.g. space docking, planetary terrain tracking). All the above topics, has been realized in the past. Either by open loop, or by man-in-loop systems. By implementing these methods or function in the onboard autonomy, a superior system performance could be acheived by means...

Monolithic microwave integrated circuit technology for advanced space communication

Science.gov (United States)

Ponchak, George E.; Romanofsky, Robert R.

1988-01-01

Future Space Communications subsystems will utilize GaAs Monolithic Microwave Integrated Circuits (MMIC's) to reduce volume, weight, and cost and to enhance system reliability. Recent advances in GaAs MMIC technology have led to high-performance devices which show promise for insertion into these next generation systems. The status and development of a number of these devices operating from Ku through Ka band will be discussed along with anticipated potential applications.

Development of Advanced Robotic Hand System for space application

Science.gov (United States)

Machida, Kazuo; Akita, Kenzo; Mikami, Tatsuo; Komada, Satoru

1994-01-01

The Advanced Robotic Hand System (ARH) is a precise telerobotics system with a semi dexterous hand for future space application. The ARH will be tested in space as one of the missions of the Engineering Tests Satellite 7 (ETS-7) which will be launched in 1997. The objectives of the ARH development are to evaluate the capability of a possible robot hand for precise and delicate tasks and to validate the related technologies implemented in the system. The ARH is designed to be controlled both from ground as a teleoperation and by locally autonomous control. This paper presents the overall system design and the functional capabilities of the ARH as well as its mission outline as the preliminary design has been completed.

Comparison of bimodal and bilateral cochlear implant users on speech recognition with competing talker, music perception, affective prosody discrimination, and talker identification.

Science.gov (United States)

Cullington, Helen E; Zeng, Fan-Gang

2011-02-01

Despite excellent performance in speech recognition in quiet, most cochlear implant users have great difficulty with speech recognition in noise, music perception, identifying tone of voice, and discriminating different talkers. This may be partly due to the pitch coding in cochlear implant speech processing. Most current speech processing strategies use only the envelope information; the temporal fine structure is discarded. One way to improve electric pitch perception is to use residual acoustic hearing via a hearing aid on the nonimplanted ear (bimodal hearing). This study aimed to test the hypothesis that bimodal users would perform better than bilateral cochlear implant users on tasks requiring good pitch perception. Four pitch-related tasks were used. 1. Hearing in Noise Test (HINT) sentences spoken by a male talker with a competing female, male, or child talker. 2. Montreal Battery of Evaluation of Amusia. This is a music test with six subtests examining pitch, rhythm and timing perception, and musical memory. 3. Aprosodia Battery. This has five subtests evaluating aspects of affective prosody and recognition of sarcasm. 4. Talker identification using vowels spoken by 10 different talkers (three men, three women, two boys, and two girls). Bilateral cochlear implant users were chosen as the comparison group. Thirteen bimodal and 13 bilateral adult cochlear implant users were recruited; all had good speech perception in quiet. There were no significant differences between the mean scores of the bimodal and bilateral groups on any of the tests, although the bimodal group did perform better than the bilateral group on almost all tests. Performance on the different pitch-related tasks was not correlated, meaning that if a subject performed one task well they would not necessarily perform well on another. The correlation between the bimodal users' hearing threshold levels in the aided ear and their performance on these tasks was weak. Although the bimodal cochlear

Cermet fuels for space power systems

International Nuclear Information System (INIS)

Barner, J.O.; Coomes, E.P.; Williford, R.E.; Neimark, L.A.

1986-01-01

A refractory-metal matrix, UN-fueled cermet is a very promising fuel candidate for a wide range of multi-megawatt space reactor systems, e.g., steady-state, flexible duty-cycle, or bimodal, single- or two-phase liquid-metal cooled reactors, or thermionic reactors. Cermet fuel is especially promising for reactor designs that require operational strategies which incorporate rapid power changes because of its anticipated capability to withstand thermal shock

Mobile Education: Towards Affective Bi-modal Interaction for Adaptivity

Directory of Open Access Journals (Sweden)

Efthymios Alepis

2009-04-01

Full Text Available One important field where mobile technology can make significant contributions is education. However one criticism in mobile education is that students receive impersonal teaching. Affective computing may give a solution to this problem. In this paper we describe an affective bi-modal educational system for mobile devices. In our research we describe a novel approach of combining information from two modalities namely the keyboard and the microphone through a multi-criteria decision making theory.

Velocity selection for ultra-cold atoms using bimodal mazer cavity

International Nuclear Information System (INIS)

Irshad, A.; Qamar, S.

2009-04-01

In this paper, we discuss the velocity selection of ultra-cold three-level atoms in Λ configuration using a micromazer. Our model is the same as discussed by Arun et al., for mazer action in a bimodal cavity. We have shown that significantly narrowed velocity distribution of ultra-cold atoms can be obtained in this system due to the presence of dark states. (author)

Authentically radiolabelled Mn(II) complexes as bimodal PET/MR tracers

Energy Technology Data Exchange (ETDEWEB)

Vanasschen, Christian; Brandt, Marie; Ermert, Johannes [Institute of Neuroscience and Medicine, INM-5 - Nuclear Chemistry, Forschungszentrum Jülich (Germany); Neumaier, Bernd [Institute for Radiochemistry and Experimental Molecular Imaging, Medical Clinics, University of Cologne (Germany); Coenen, Heinz H [Institute of Neuroscience and Medicine, INM-5 - Nuclear Chemistry, Forschungszentrum Jülich (Germany)

2015-05-18

The development of small molecule bimodal PET/MR tracers is mainly hampered by the lack of dedicated preparation methods. Authentic radiolabelling of MR contrast agents ensures easy access to such probes: a ligand, chelating a paramagnetic metal ion (e.g. Mn2+) and the corresponding PET isotope (e.g. 52gMn), leads to a “cocktail mixture” where both imaging reporters exhibit the same pharmacokinetics. Paramagnetic [55Mn(CDTA)]2- shows an excellent compromise between thermodynamic stability, kinetic inertness and MR contrast enhancement. Therefore, the aim of this study was to develop new PET/MR tracers by labelling CDTA ligands with paramagnetic manganese and the β+-emitter 52gMn. N.c.a. 52gMn (t1/2: 5.6 d; Eβ+: 575.8 keV (29.6%)) was produced by proton irradiation of a natCr target followed by cation-exchange chromatography. CDTA was radiolabelled with n.c.a. 52gMn2+ in NaOAc buffer (pH 6) at RT. The complex was purified by RP-HPLC and its stability tested in PBS and blood plasma at 37°C. The redox stability was assessed by monitoring the T1 relaxation (20 MHz) in HEPES buffer (pH 7.4). A functionalized CDTA ligand was synthesized in 5 steps. [52gMn(CDTA)]2- was quantitatively formed within 30 min at RT. The complex was stable for at least 6 days in PBS and blood plasma at 37°C and no oxidation occurred within 7 months storage at RT. Labelling CDTA with an isotopic 52g/55Mn2+ mixture led to the corresponding bimodal PET/MR tracer. Furthermore, a functionalized CDTA ligand was synthesized with an overall yield of 18-25%. [52g/55Mn(CDTA)]2-, the first manganese-based bimodal PET/MR tracer prepared, exhibits excellent stability towards decomplexation and oxidation. This makes the functionalized CDTA ligand highly suitable for designing PET/MR tracers with high relaxivity or targeting properties.

Authentically radiolabelled Mn(II) complexes as bimodal PET/MR tracers

International Nuclear Information System (INIS)

Vanasschen, Christian; Brandt, Marie; Ermert, Johannes; Neumaier, Bernd; Coenen, Heinz H

2015-01-01

The development of small molecule bimodal PET/MR tracers is mainly hampered by the lack of dedicated preparation methods. Authentic radiolabelling of MR contrast agents ensures easy access to such probes: a ligand, chelating a paramagnetic metal ion (e.g. Mn2+) and the corresponding PET isotope (e.g. 52gMn), leads to a “cocktail mixture” where both imaging reporters exhibit the same pharmacokinetics. Paramagnetic [55Mn(CDTA)]2- shows an excellent compromise between thermodynamic stability, kinetic inertness and MR contrast enhancement. Therefore, the aim of this study was to develop new PET/MR tracers by labelling CDTA ligands with paramagnetic manganese and the β+-emitter 52gMn. N.c.a. 52gMn (t1/2: 5.6 d; Eβ+: 575.8 keV (29.6%)) was produced by proton irradiation of a natCr target followed by cation-exchange chromatography. CDTA was radiolabelled with n.c.a. 52gMn2+ in NaOAc buffer (pH 6) at RT. The complex was purified by RP-HPLC and its stability tested in PBS and blood plasma at 37°C. The redox stability was assessed by monitoring the T1 relaxation (20 MHz) in HEPES buffer (pH 7.4). A functionalized CDTA ligand was synthesized in 5 steps. [52gMn(CDTA)]2- was quantitatively formed within 30 min at RT. The complex was stable for at least 6 days in PBS and blood plasma at 37°C and no oxidation occurred within 7 months storage at RT. Labelling CDTA with an isotopic 52g/55Mn2+ mixture led to the corresponding bimodal PET/MR tracer. Furthermore, a functionalized CDTA ligand was synthesized with an overall yield of 18-25%. [52g/55Mn(CDTA)]2-, the first manganese-based bimodal PET/MR tracer prepared, exhibits excellent stability towards decomplexation and oxidation. This makes the functionalized CDTA ligand highly suitable for designing PET/MR tracers with high relaxivity or targeting properties.

Spacecraft Conceptual Design for the 8-Meter Advanced Technology Large Aperture Space Telescope (ATLAST)

Science.gov (United States)

Hopkins, Randall C.; Capizzo, Peter; Fincher, Sharon; Hornsby, Linda S.; Jones, David

2010-01-01

The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8-meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

Propulsion/ASME Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

Science.gov (United States)

Hueter, Uwe; Turner, James

1998-01-01

NASA's Office Of Aeronautics and Space Transportation Technology (OASTT) has establish three major coals. "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville,Ala. focuses on future space transportation technologies under the "Access to Space" pillar. The Advanced Reusable Technologies (ART) Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. The main activity over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the year 2000 decision to determine the path this country will take for Space Shuttle and RLV. In February of this year, additional technology efforts in the reusable technologies were awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion. Aerojet, Boeing-Rocketdyne and Pratt & Whitney were selected for a two-year period to design, build and ground test their RBCC engine concepts. In addition, ASTROX, Pennsylvania State University (PSU) and University of Alabama in Huntsville also conducted supporting activities. The activity included ground testing of components (e.g., injectors, thrusters, ejectors and inlets) and integrated flowpaths. An area that has caused a large amount of difficulty in the testing efforts is the means of initiating the rocket combustion process. All three of the prime contractors above were using silane (SiH4) for ignition of the thrusters. This follows from the successful use of silane in the NASP program for scramjet ignition. However, difficulties were immediately encountered when silane (an 80/20 mixture of hydrogen/silane) was used for rocket

Atmosphere composition monitor for space station and advanced missions application

International Nuclear Information System (INIS)

Wynveen, R.A.; Powell, F.T.

1987-01-01

Long-term human occupation of extraterrestrial locations may soon become a reality. The National Aeronautics and Space Administration (NASA) has recently completed the definition and preliminary design of the low earth orbit (LEO) space station. They are now currently moving into the detailed design and fabrication phase of this space station and are also beginning to analyze the requirements of several future missions that have been identified. These missions include, for example, Lunar and Mars sorties, outposts, bases, and settlements. A requirement of both the LEO space station and future missions are environmental control and life support systems (ECLSS), which provide a comfortable environment for humans to live and work. The ECLSS consists of several major systems, including atmosphere revitalization system (ARS), atmosphere pressure and composition control system, temperature and humidity control system, water reclamation system, and waste management system. Each of these major systems is broken down into subsystems, assemblies, units, and instruments. Many requirements and design drivers are different for the ECLSS of the LEO space station and the identified advanced missions (e.g., longer mission duration). This paper discusses one of the ARS assemblies, the atmosphere composition monitor assembly (ACMA), being developed for the LEO space station and addresses differences that will exist for the ACMA of future missions

Bimodality in macroscopic dynamics of nuclear fission

International Nuclear Information System (INIS)

Bastrukov, S.I.; Salamatin, V.S.; Strteltsova, O.I.; Molodtsova, I.V.; Podgainy, D.V.; )

2000-01-01

The elastodynamic collective model of nuclear fission is outlined whose underlying idea is that the stiff structure of nuclear shells imparts to nucleus properties typical of a small piece of an elastic solid. Emphasis is placed on the macroscopic dynamics of nuclear deformations resulting in fission by two energetically different modes. The low-energy S-mode is the fission due to disruption of elongated quadrupole spheroidal shape. The characteristic features of the high-energy T-mode of division by means of torsional shear deformations is the compact scission configuration. Analytic and numerical estimates for the macroscopic fission-barrier heights are presented, followed by discussion of fingerprints of the above dynamical bimodality in the available data [ru

Advancing Autonomous Operations for Deep Space Vehicles

Science.gov (United States)

Haddock, Angie T.; Stetson, Howard K.

2014-01-01

Starting in Jan 2012, the Advanced Exploration Systems (AES) Autonomous Mission Operations (AMO) Project began to investigate the ability to create and execute "single button" crew initiated autonomous activities [1]. NASA Marshall Space Flight Center (MSFC) designed and built a fluid transfer hardware test-bed to use as a sub-system target for the investigations of intelligent procedures that would command and control a fluid transfer test-bed, would perform self-monitoring during fluid transfers, detect anomalies and faults, isolate the fault and recover the procedures function that was being executed, all without operator intervention. In addition to the development of intelligent procedures, the team is also exploring various methods for autonomous activity execution where a planned timeline of activities are executed autonomously and also the initial analysis of crew procedure development. This paper will detail the development of intelligent procedures for the NASA MSFC Autonomous Fluid Transfer System (AFTS) as well as the autonomous plan execution capabilities being investigated. Manned deep space missions, with extreme communication delays with Earth based assets, presents significant challenges for what the on-board procedure content will encompass as well as the planned execution of the procedures.

Towards a Global Hub and a Network for Collaborative Advancing of Space Weather Predictive Capabilities.

Science.gov (United States)

Kuznetsova, M. M.; Heynderickz, D.; Grande, M.; Opgenoorth, H. J.

2017-12-01

The COSPAR/ILWS roadmap on space weather published in 2015 (Advances in Space Research, 2015: DOI: 10.1016/j.asr.2015.03.023) prioritizes steps to be taken to advance understanding of space environment phenomena and to improve space weather forecasting capabilities. General recommendations include development of a comprehensive space environment specification, assessment of the state of the field on a 5-yr basis, standardization of meta-data and product metrics. To facilitate progress towards roadmap goals there is a need for a global hub for collaborative space weather capabilities assessment and development that brings together research, engineering, operational, educational, and end-user communities. The COSPAR Panel on Space Weather is aiming to build upon past progress and to facilitate coordination of established and new international space weather research and development initiatives. Keys to the success include creating flexible, collaborative, inclusive environment and engaging motivated groups and individuals committed to active participation in international multi-disciplinary teams focused on topics addressing emerging needs and challenges in the rapidly growing field of space weather. Near term focus includes comprehensive assessment of the state of the field and establishing an internationally recognized process to quantify and track progress over time, development of a global network of distributed web-based resources and interconnected interactive services required for space weather research, analysis, forecasting and education.

Constraining second language word order optionality : scrambling in advanced English-German and Japanese-German interlanguage

NARCIS (Netherlands)

Hopp, Holger

2005-01-01

This study documents knowledge of UG-mediated aspects of optionality in word order in the second language (L2) German of advanced English and Japanese speakers (n = 39). A bimodal grammaticality judgement task, which controlled for context and intonation, was administered to probe judgements on a

Time shift in slope failure prediction between unimodal and bimodal modeling approaches

Science.gov (United States)

Ciervo, Fabio; Casini, Francesca; Nicolina Papa, Maria; Medina, Vicente

2016-04-01

Together with the need to use more appropriate mathematical expressions for describing hydro-mechanical soil processes, a challenge issue relates to the need of considering the effects induced by terrain heterogeneities on the physical mechanisms, taking into account the implications of the heterogeneities in affecting time-dependent hydro-mechanical variables, would improve the prediction capacities of models, such as the ones used in early warning systems. The presence of the heterogeneities in partially-saturated slopes results in irregular propagation of the moisture and suction front. To mathematically represent the "dual-implication" generally induced by the heterogeneities in describing the hydraulic terrain behavior, several bimodal hydraulic models have been presented in literature and replaced the conventional sigmoidal/unimodal functions; this presupposes that the scale of the macrostructure is comparable with the local scale (Darcy scale), thus the Richards' model can be assumed adequate to mathematically reproduce the processes. The purpose of this work is to focus on the differences in simulating flow infiltration processes and slope stability conditions originated from preliminary choices of hydraulic models and contextually between different approaches to evaluate the factor of safety (FoS). In particular, the results of two approaches are compared. The first one includes the conventional expression of the FoS under saturated conditions and the widespread used hydraulic model of van Genuchten-Mualem. The second approach includes a generalized FoS equation for infinite-slope model under variably saturated soil conditions (Lu and Godt, 2008) and the bimodal Romano et al.'s (2011) functions to describe the hydraulic response. The extension of the above mentioned approach to the bimodal context is based on an analytical method to assess the effects of the hydraulic properties on soil shear developed integrating a bimodal lognormal hydraulic function

The Bi-Modal Organization: Balancing Autopoiesis and Fluid Social Networks for Sustainability

Science.gov (United States)

Smith, Peter A. C.; Sharicz, Carol Ann

2013-01-01

Purpose: The purpose of this paper is to assist an organization to restructure as a bi-modal organization in order to achieve sustainability in today's highly complex business world. Design/methodology/approach: The paper is conceptual and is based on relevant literature and the authors' research and practice. Findings: Although fluid…

The Legion Support for Advanced Parameter-Space Studies on a Grid

National Research Council Canada - National Science Library

Natrajan, Anand; Humphrey, Marty A; Grimshaw, Andrew S

2006-01-01

.... Legion provides tools and services that support advanced parameter-space studies, i.e., studies that make complex demands such as transparent access to distributed files, fault-tolerance and security. We demonstrate these benefits with a protein-folding experiment in which a molecular simulation package was run over a grid managed by Legion.

The trade-off between heat tolerance and metabolic cost drives the bimodal life strategy at the air-water interface

KAUST Repository

Fusi, Marco; Cannicci, Stefano; Daffonchio, Daniele; Mostert, Bruce; Pö rtner, Hans-Otto; Giomi, Folco

2016-01-01

The principle of oxygen and capacity limitation of thermal tolerance in ectotherms suggests that the long-term upper limits of an organism's thermal niche are equivalent to the upper limits of the organism's functional capacity for oxygen provision to tissues. Air-breathing ectotherms show wider thermal tolerances, since they can take advantage of the higher availability of oxygen in air than in water. Bimodal species move from aquatic to aerial media and switch between habitats in response to environmental variations such as cyclical or anomalous temperature fluctuations. Here we tested the prediction that bimodal species cope better with thermal stress than truly aquatic species using the crab Pachygrapsus marmoratus as a model species. When in water, oxygen consumption rates of P. marmoratus acutely rise during warming. Beyond a temperature threshold of 23 °C the crab's aerobic metabolism in air remains lower than in water. In parallel, the haemolymph oxygen partial pressure of submerged animals progressive decreases during warming, while it remains low but constant during emersion. Our results demonstrate the ability of a bimodal breathing ectotherm to extend its thermal tolerance during air-breathing, suggesting that there are temperature-related physiological benefits during the evolution of the bimodal life style.

The trade-off between heat tolerance and metabolic cost drives the bimodal life strategy at the air-water interface

KAUST Repository

Fusi, Marco

2016-01-13

The principle of oxygen and capacity limitation of thermal tolerance in ectotherms suggests that the long-term upper limits of an organism\\'s thermal niche are equivalent to the upper limits of the organism\\'s functional capacity for oxygen provision to tissues. Air-breathing ectotherms show wider thermal tolerances, since they can take advantage of the higher availability of oxygen in air than in water. Bimodal species move from aquatic to aerial media and switch between habitats in response to environmental variations such as cyclical or anomalous temperature fluctuations. Here we tested the prediction that bimodal species cope better with thermal stress than truly aquatic species using the crab Pachygrapsus marmoratus as a model species. When in water, oxygen consumption rates of P. marmoratus acutely rise during warming. Beyond a temperature threshold of 23 °C the crab\\'s aerobic metabolism in air remains lower than in water. In parallel, the haemolymph oxygen partial pressure of submerged animals progressive decreases during warming, while it remains low but constant during emersion. Our results demonstrate the ability of a bimodal breathing ectotherm to extend its thermal tolerance during air-breathing, suggesting that there are temperature-related physiological benefits during the evolution of the bimodal life style.

Bi-Modal Face and Speech Authentication: a BioLogin Demonstration System

OpenAIRE

Marcel, Sébastien; Mariéthoz, Johnny; Rodriguez, Yann; Cardinaux, Fabien

2006-01-01

This paper presents a bi-modal (face and speech) authentication demonstration system that simulates the login of a user using its face and its voice. This demonstration is called BioLogin. It runs both on Linux and Windows and the Windows version is freely available for download. Bio\\-Login is implemented using an open source machine learning library and its machine vision package.

Bimodal MR-PET agent for quantitative pH imaging

Science.gov (United States)

Frullano, Luca; Catana, Ciprian; Benner, Thomas; Sherry, A. Dean; Caravan, Peter

2010-01-01

Activatable or “smart” magnetic resonance contrast agents have relaxivities that depend on environmental factors such as pH or enzymatic activity, but the MR signal depends on relaxivity and agent concentration – two unknowns. A bimodal approach, incorporating a positron emitter, solves this problem. Simultaneous positron emission tomography (PET) and MR imaging with the biomodal, pH-responsive MR-PET agent GdDOTA-4AMP-F allows direct determination of both concentration (PET) and T1 (MRI), and hence pH. PMID:20191650

Advances in Autonomous Systems for Missions of Space Exploration

Science.gov (United States)

Gross, A. R.; Smith, B. D.; Briggs, G. A.; Hieronymus, J.; Clancy, D. J.

New missions of space exploration will require unprecedented levels of autonomy to successfully accomplish their objectives. Both inherent complexity and communication distances will preclude levels of human involvement common to current and previous space flight missions. With exponentially increasing capabilities of computer hardware and software, including networks and communication systems, a new balance of work is being developed between humans and machines. This new balance holds the promise of meeting the greatly increased space exploration requirements, along with dramatically reduced design, development, test, and operating costs. New information technologies, which take advantage of knowledge-based software, model-based reasoning, and high performance computer systems, will enable the development of a new generation of design and development tools, schedulers, and vehicle and system health monitoring and maintenance capabilities. Such tools will provide a degree of machine intelligence and associated autonomy that has previously been unavailable. These capabilities are critical to the future of space exploration, since the science and operational requirements specified by such missions, as well as the budgetary constraints that limit the ability to monitor and control these missions by a standing army of ground- based controllers. System autonomy capabilities have made great strides in recent years, for both ground and space flight applications. Autonomous systems have flown on advanced spacecraft, providing new levels of spacecraft capability and mission safety. Such systems operate by utilizing model-based reasoning that provides the capability to work from high-level mission goals, while deriving the detailed system commands internally, rather than having to have such commands transmitted from Earth. This enables missions of such complexity and communications distance as are not otherwise possible, as well as many more efficient and low cost

Processing bimodal stimulus information under alcohol: is there a risk to being redundant?

Science.gov (United States)

Fillmore, Mark T

2010-10-01

The impairing effects of alcohol are especially pronounced in environments that involve dividing attention across two or more stimuli. However, studies in cognitive psychology have identified circumstances in which the presentation of multiple stimuli can actually facilitate performance. The "redundant signal effect" (RSE) refers to the observation that individuals respond more quickly when information is presented as redundant, bimodal stimuli (e.g., aurally and visually), rather than as a single stimulus presented to either modality alone. The present study tested the hypothesis that the response facilitation attributed to RSE could reduce the degree to which alcohol slows information processing. Two experiments are reported. Experiment 1 demonstrated the validity of a reaction time model of RSE by showing that adults (N = 15) responded more quickly to redundant, bimodal stimuli (visual + aural) versus either stimuli presented individually. Experiment 2 used the RSE model to test the reaction time performance of 20 adults following three alcohol doses (0.0 g/kg, 0.45 g/kg, and 0.65 g/kg). Results showed that alcohol slowed reaction time in a general dose-dependent manner in all three stimulus conditions with the reaction time (RT) speed-advantage of the redundant signal being maintained, even under the highest dose of alcohol. Evidence for an RT advantage to bimodal stimuli under alcohol challenges the general assumption that alcohol impairment is intensified in multistimulus environments. The current study provides a useful model to investigate how drug effects on behavior might be altered in contexts that involve redundant response signals.

The Taylor-expansion method of moments for the particle system with bimodal distribution

Directory of Open Access Journals (Sweden)

Liu Yan-Hua

2013-01-01

Full Text Available This paper derives the multipoint Taylor expansion method of moments for the bimodal particle system. The collision effects are modeled by the internal and external coagulation terms. Simple theory and numerical tests are performed to prove the effect of the current model.

Advanced biosensors for monitoring astronauts' health during long-duration space missions.

Science.gov (United States)

Roda, Aldo; Mirasoli, Mara; Guardigli, Massimo; Zangheri, Martina; Caliceti, Cristiana; Calabria, Donato; Simoni, Patrizia

2018-07-15

Long-duration space missions pose important health concerns for astronauts, especially regarding the adverse effects of microgravity and exposure to high-energy cosmic rays. The long-term maintenance of crew health and performance mainly relies on prevention, early diagnoses, condition management, and medical interventions in situ. In-flight biosensor diagnostic devices and medical procedures must use few resources and operate in a microgravity environment, which complicates the collection and management of biological samples. Moreover, the biosensors must be certified for in-flight operation according to strict design and safety regulations. Herein, we report on the state of the art and recent advances in biosensing diagnostic instrumentation for monitoring astronauts' health during long-duration space missions, including portable and wearable biosensors. We discuss perspectives on new-format biosensors in autonomous space clinics. We also describe our own work in developing biosensing devices for non-invasively diagnosing space-related diseases, and how they are used in long-duration missions. Finally, we discuss the benefits of space exploration for Earth-based medicine. Copyright © 2018 Elsevier B.V. All rights reserved.

Proceedings of the 30. intersociety energy conversion engineering conference. Volume 1

International Nuclear Information System (INIS)

Goswami, D.Y.; Kannberg, L.D.; Somasundaram, S.

1995-01-01

This conference provides a forum to present and discuss the engineering aspects of energy conversion, advanced and unconventional energy systems and devices, energy conversion and utilization, environmental issues and policy implications on research, development, and implementation of technologies. The solution for a sustainable future will lie in a mix of all of the available energy resources (renewable and non-renewable) and diverse energy conversion technologies that will maintain quality of life in a sustainable manner. The 129 papers in Volume 1 deal with aerospace power and are divided into the following topical sections: Aircraft power; Aerospace power systems; Batteries for aerospace power; Computer simulation; Power electronics; Power management; Space solar power; Space power systems; Space energy statics/dynamics; Space power--requirements and issues; Space Station power; Terrestrial applications of space power; Thermal management; Wireless transmission; Space nuclear power; Bimodal propulsion; Electric propulsion; Solar thermal; and Solar bimodal. All papers have been processed separately for inclusion on the data base

Contralateral Bimodal Stimulation: A Way to Enhance Speech Performance in Arabic-Speaking Cochlear Implant Patients.

Science.gov (United States)

Abdeltawwab, Mohamed M; Khater, Ahmed; El-Anwar, Mohammad W

2016-01-01

The combination of acoustic and electric stimulation as a way to enhance speech recognition performance in cochlear implant (CI) users has generated considerable interest in the recent years. The purpose of this study was to evaluate the bimodal advantage of the FS4 speech processing strategy in combination with hearing aids (HA) as a means to improve low-frequency resolution in CI patients. Nineteen postlingual CI adults were selected to participate in this study. All patients wore implants on one side and HA on the contralateral side with residual hearing. Monosyllabic word recognition, speech in noise, and emotion and talker identification were assessed using CI with fine structure processing/FS4 and high-definition continuous interleaved sampling strategies, HA alone, and a combination of CI and HA. The bimodal stimulation showed improvement in speech performance and emotion identification for the question/statement/order tasks, which was statistically significant compared to patients with CI alone, but there were no significant statistical differences in intragender talker discrimination and emotion identification for the happy/angry/neutral tasks. The poorest performance was obtained with HA only, and it was statistically significant compared to the other modalities. The bimodal stimulation showed enhanced speech performance in CI patients, and it improves the limitations provided by electric or acoustic stimulation alone. © 2016 S. Karger AG, Basel.

High temperature tensile properties and fracture characteristics of bimodal 12Cr-ODS steel

International Nuclear Information System (INIS)

Chauhan, Ankur; Litvinov, Dimitri; Aktaa, Jarir

2016-01-01

This article describes the tensile properties and fracture characteristics of a 12Cr oxide dispersion strengthened (ODS) ferritic steel with unique elongated bimodal grain size distribution. The tensile tests were carried out at four different temperatures, ranging from room temperature to 700 °C, at a nominal strain rate of 10"−"3 s"−"1. At room temperature the material exhibits a high tensile strength of 1294 MPa and high yield strength of 1200 MPa. At 700 °C, the material still exhibits relatively high tensile strength of 300 MPa. The total elongation-to-failure exceeds 18% over the whole temperature range and has a maximum value of 29% at 600 °C. This superior ductility is attributed to the material's bimodal grain size distribution. In comparison to other commercial, as well as experimental, ODS steels, the material shows an excellent compromise between strength and ductility. The fracture surface studies reveal a change in fracture behavior from a mixed mode fracture at room temperature to fully ductile fracture at 600 °C. At 700 °C, the fracture path changes from intragranular to intergranular fracture, which is associated with a reduced ductility. - Highlights: • The steel has a unique elongated bimodal grain size distribution. • The steel shows an excellent compromise between strength and ductility. • Superior ductility in comparison to other commercial and experimental ODS steels. • Fracture behavior changes from mixed mode fracture at room temperature to fully ductile fracture at 600 °C. • Fracture path changes from intragranular to intergranular fracture at 700 °C.

Movement, drivers and bimodality of the South Asian High

Directory of Open Access Journals (Sweden)

M. Nützel

2016-11-01

Full Text Available The South Asian High (SAH is an important component of the summer monsoon system in Asia. In this study we investigate the location and drivers of the SAH at 100 hPa during the boreal summers of 1979 to 2014 on interannual, seasonal and synoptic timescales using seven reanalyses and observational data. Our comparison of the different reanalyses focuses especially on the bimodality of the SAH, i.e. the two preferred modes of the SAH centre location: the Iranian Plateau to the west and the Tibetan Plateau to the east. We find that only the National Centers for Environmental Prediction–National Center of Atmospheric Research (NCEP–NCAR reanalysis shows a clear bimodal structure of the SAH centre distribution with respect to daily and pentad (5 day mean data. Furthermore, the distribution of the SAH centre location is highly variable from year to year. As in simple model studies, which connect the SAH to heating in the tropics, we find that the mean seasonal cycle of the SAH and its centre are dominated by the expansion of convection in the South Asian region (70–130° E  ×  15–30° N on the south-eastern border of the SAH. A composite analysis of precipitation and outgoing long-wave radiation data with respect to the location of the SAH centre reveals that a more westward (eastward location of the SAH is related to stronger (weaker convection and rainfall over India and weaker (stronger precipitation over the western Pacific.

Bimodality: A Sign of Critical Behavior in Nuclear Reactions

International Nuclear Information System (INIS)

Le Fevre, A.; Aichelin, J.

2008-01-01

The recently discovered coexistence of multifragmentation and residue production for the same total transverse energy of light charged particles, which has been dubbed bimodality like it has been introduced in the framework of equilibrium thermodynamics, can be well reproduced in numerical simulations of heavy ion reactions. A detailed analysis shows that fluctuations (introduced by elementary nucleon-nucleon collisions) determine which of the exit states is realized. Thus, we can identify bifurcation in heavy ion reactions as a critical phenomenon. Also the scaling of the coexistence region with beam energy is well reproduced in these results from the quantum molecular dynamics simulation program

Effects of Removing Low-Frequency Electric Information on Speech Perception with Bimodal Hearing

Science.gov (United States)

Fowler, Jennifer R.; Eggleston, Jessica L.; Reavis, Kelly M.; McMillan, Garnett P.; Reiss, Lina A. J.

2016-01-01

Purpose: The objective was to determine whether speech perception could be improved for bimodal listeners (those using a cochlear implant [CI] in one ear and hearing aid in the contralateral ear) by removing low-frequency information provided by the CI, thereby reducing acoustic-electric overlap. Method: Subjects were adult CI subjects with at…

Merging history of three bimodal clusters

Science.gov (United States)

Maurogordato, S.; Sauvageot, J. L.; Bourdin, H.; Cappi, A.; Benoist, C.; Ferrari, C.; Mars, G.; Houairi, K.

2011-01-01

We present a combined X-ray and optical analysis of three bimodal galaxy clusters selected as merging candidates at z ~ 0.1. These targets are part of MUSIC (MUlti-Wavelength Sample of Interacting Clusters), which is a general project designed to study the physics of merging clusters by means of multi-wavelength observations. Observations include spectro-imaging with XMM-Newton EPIC camera, multi-object spectroscopy (260 new redshifts), and wide-field imaging at the ESO 3.6 m and 2.2 m telescopes. We build a global picture of these clusters using X-ray luminosity and temperature maps together with galaxy density and velocity distributions. Idealized numerical simulations were used to constrain the merging scenario for each system. We show that A2933 is very likely an equal-mass advanced pre-merger ~200 Myr before the core collapse, while A2440 and A2384 are post-merger systems (~450 Myr and ~1.5 Gyr after core collapse, respectively). In the case of A2384, we detect a spectacular filament of galaxies and gas spreading over more than 1 h-1 Mpc, which we infer to have been stripped during the previous collision. The analysis of the MUSIC sample allows us to outline some general properties of merging clusters: a strong luminosity segregation of galaxies in recent post-mergers; the existence of preferential axes - corresponding to the merging directions - along which the BCGs and structures on various scales are aligned; the concomitance, in most major merger cases, of secondary merging or accretion events, with groups infalling onto the main cluster, and in some cases the evidence of previous merging episodes in one of the main components. These results are in good agreement with the hierarchical scenario of structure formation, in which clusters are expected to form by successive merging events, and matter is accreted along large-scale filaments. Based on data obtained with the European Southern Observatory, Chile (programs 072.A-0595, 075.A-0264, and 079.A-0425

Phenol-formaldehyde carbon with ordered/disordered bimodal mesoporous structure as high-performance electrode materials for supercapacitors

Science.gov (United States)

Cai, Tingwei; Zhou, Min; Han, Guangshuai; Guan, Shiyou

2013-11-01

A novel phenol-formaldehyde carbon with ordered/disordered bimodal mesoporous structure is synthesized by the facile evaporation induced self-assembly strategy under a basic aqueous condition with SiO2 particles as template. The prepared bimodal mesoporous carbons (BMCs) are composed of ordered mesoporous and disordered mesoporous with diameter of about 3.5 nm and 7.0 nm, respectively. They can be employed as supercapacitor electrodes in H2SO4 aqueous electrolyte after the simple acid-treatment. BMC exhibits an exceptional specific capacitance of 344 F g-1 at the current density of 0.1 A g-1, although it has a relatively low surface area of 722 m2 g-1. And the BMC electrode displays an excellent cycling stability over 10,000 cycles.

An assessment of advanced displays and controls technology applicable to future space transportation systems

Science.gov (United States)

Hatfield, Jack J.; Villarreal, Diana

1990-01-01

The topic of advanced display and control technology is addressed along with the major objectives of this technology, the current state of the art, major accomplishments, research programs and facilities, future trends, technology issues, space transportation systems applications and projected technology readiness for those applications. The holes that may exist between the technology needs of the transportation systems versus the research that is currently under way are addressed, and cultural changes that might facilitate the incorporation of these advanced technologies into future space transportation systems are recommended. Some of the objectives are to reduce life cycle costs, improve reliability and fault tolerance, use of standards for the incorporation of advancing technology, and reduction of weight, volume and power. Pilot workload can be reduced and the pilot's situational awareness can be improved, which would result in improved flight safety and operating efficiency. This could be accomplished through the use of integrated, electronic pictorial displays, consolidated controls, artificial intelligence, and human centered automation tools. The Orbiter Glass Cockpit Display is an example examined.

The Medial Ventrothalamic Circuitry: Cells Implicated in a Bimodal Network

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Tomas Vega-Zuniga

2018-02-01

Full Text Available Previous avian thalamic studies have shown that the medial ventral thalamus is composed of several nuclei located close to the lateral wall of the third ventricle. Although the general connectivity is known, detailed morphology and connectivity pattern in some regions are still elusive. Here, using the intracellular filling technique in the chicken, we focused on two neural structures, namely, the retinorecipient neuropil of the n. geniculatus lateralis pars ventralis (GLv, and the adjacent n. intercalatus thalami (ICT. We found that the GLv-ne cells showed two different neuronal types: projection cells and horizontal interneurons. The projection cells showed variable morphologies and dendritic arborizations with axons that targeted the n. lentiformis mesencephali (LM, griseum tectale (GT, ICT, n. principalis precommissuralis (PPC, and optic tectum (TeO. The horizontal cells showed a widespread mediolateral neural process throughout the retinorecipient GLv-ne. The ICT cells, on the other hand, had multipolar somata with wide dendritic fields that extended toward the lamina interna of the GLv, and a projection pattern that targeted the n. laminaris precommissuralis (LPC. Together, these results elucidate the rich complexity of the connectivity pattern so far described between the GLv, ICT, pretectum, and tectum. Interestingly, the implication of some of these neural structures in visuomotor and somatosensory roles strongly suggests that the GLv and ICT are part of a bimodal circuit that may be involved in the generation/modulation of saccades, gaze control, and space perception.

Motivating and Facilitating Advancements in Space Weather Real-Time Data Availability: Factors, Data, and Access Methods

Science.gov (United States)

Pankratz, C. K.; Baker, D. N.; Jaynes, A. N.; Elkington, S. R.; Baltzer, T.; Sanchez, F.

2017-12-01

Society's growing reliance on complex and highly interconnected technological systems makes us increasingly vulnerable to the effects of space weather events - maybe more than for any other natural hazard. An extreme solar storm today could conceivably impact hundreds of the more than 1400 operating Earth satellites. Such an extreme storm could cause collapse of the electrical grid on continental scales. The effects on navigation, communication, and remote sensing of our home planet could be devastating to our social functioning. Thus, it is imperative that the scientific community address the question of just how severe events might become. At least as importantly, it is crucial that policy makers and public safety officials be informed by the facts on what might happen during extreme conditions. This requires essentially real-time alerts, warnings, and also forecasts of severe space weather events, which in turn demands measurements, models, and associated data products to be available via the most effective data discovery and access methods possible. Similarly, advancement in the fundamental scientific understanding of space weather processes is also vital, requiring that researchers have convenient and effective access to a wide variety of data sets and models from multiple sources. The space weather research community, as with many scientific communities, must access data from dispersed and often uncoordinated data repositories to acquire the data necessary for the analysis and modeling efforts that advance our understanding of solar influences and space physics on the Earth's environment. The Laboratory for Atmospheric and Space Physics (LASP), as a leading institution in both producing data products and advancing the state of scientific understanding of space weather processes, is well positioned to address many of these issues. In this presentation, we will outline the motivating factors for effective space weather data access, summarize the various data

Distress detection, location, and communications using advanced space technology

Science.gov (United States)

Sivertson, W. E., Jr.

1977-01-01

This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

Advances and Challenges in Space-time Modelling of Natural Events

CERN Document Server

Porcu, Emilio; Schlather, Martin

2012-01-01

This book arises as the natural continuation of the International Spring School "Advances and Challenges in Space-Time modelling of Natural Events," which took place in Toledo (Spain) in March 2010. This Spring School above all focused on young researchers (Master students, PhD students and post-doctoral researchers) in academics, extra-university research and the industry who are interested in learning about recent developments, new methods and applications in spatial statistics and related areas, and in exchanging ideas and findings with colleagues.

Advanced Exploration Technologies: Micro and Nano Technologies Enabling Space Missions in the 21st Century

Science.gov (United States)

Krabach, Timothy

1998-01-01

Some of the many new and advanced exploration technologies which will enable space missions in the 21st century and specifically the Manned Mars Mission are explored in this presentation. Some of these are the system on a chip, the Computed-Tomography imaging Spectrometer, the digital camera on a chip, and other Micro Electro Mechanical Systems (MEMS) technology for space. Some of these MEMS are the silicon micromachined microgyroscope, a subliming solid micro-thruster, a micro-ion thruster, a silicon seismometer, a dewpoint microhygrometer, a micro laser doppler anemometer, and tunable diode laser (TDL) sensors. The advanced technology insertion is critical for NASA to decrease mass, volume, power and mission costs, and increase functionality, science potential and robustness.

Affective and physiological correlates of the perception of unimodal and bimodal emotional stimuli.

Science.gov (United States)

Rosa, Pedro J; Oliveira, Jorge; Alghazzawi, Daniyal; Fardoun, Habib; Gamito, Pedro

2017-08-01

Despite the multisensory nature of perception, previous research on emotions has been focused on unimodal emotional cues with visual stimuli. To the best of our knowledge, there is no evidence on the extent to which incongruent emotional cues from visual and auditory sensory channels affect pupil size. To investigate the effects of audiovisual emotional information perception on the physiological and affective response, but also to determine the impact of mismatched cues in emotional perception on these physiological indexes. Pupil size, electrodermal activity and affective subjective responses were recorded while 30 participants were exposed to visual and auditory stimuli with varied emotional content in three different experimental conditions: pictures and sounds presented alone (unimodal), emotionally matched audio-visual stimuli (bimodal congruent) and emotionally mismatched audio-visual stimuli (bimodal incongruent). The data revealed no effect of emotional incongruence on physiological and affective responses. On the other hand, pupil size covaried with skin conductance response (SCR), but the subjective experience was partially dissociated from autonomic responses. Emotional stimuli are able to trigger physiological responses regardless of valence, sensory modality or level of emotional congruence.

Human fatigue expression recognition through image-based dynamic multi-information and bimodal deep learning

Science.gov (United States)

Zhao, Lei; Wang, Zengcai; Wang, Xiaojin; Qi, Yazhou; Liu, Qing; Zhang, Guoxin

2016-09-01

Human fatigue is an important cause of traffic accidents. To improve the safety of transportation, we propose, in this paper, a framework for fatigue expression recognition using image-based facial dynamic multi-information and a bimodal deep neural network. First, the landmark of face region and the texture of eye region, which complement each other in fatigue expression recognition, are extracted from facial image sequences captured by a single camera. Then, two stacked autoencoder neural networks are trained for landmark and texture, respectively. Finally, the two trained neural networks are combined by learning a joint layer on top of them to construct a bimodal deep neural network. The model can be used to extract a unified representation that fuses landmark and texture modalities together and classify fatigue expressions accurately. The proposed system is tested on a human fatigue dataset obtained from an actual driving environment. The experimental results demonstrate that the proposed method performs stably and robustly, and that the average accuracy achieves 96.2%.

Advanced extravehicular protective systems for shuttle, space station, lunar base and Mars missions.

Science.gov (United States)

Heimlich, P. F.; Sutton, J. G.; Tepper, E. H.

1972-01-01

Advances in extravehicular life support system technology will directly influence future space mission reliability and maintainability considerations. To identify required new technology areas, an appraisal of advanced portable life support system and subsystem concepts was conducted. Emphasis was placed on thermal control and combined CO2 control/O2 supply subsystems for both primary and emergency systems. A description of study methodology, concept evaluation techniques, specification requirements, and selected subsystems and systems are presented. New technology recommendations encompassing thermal control, CO2 control and O2 supply subsystems are also contained herein.

Research on bimodal particle extinction coefficient during Brownian coagulation and condensation for the entire particle size regime

International Nuclear Information System (INIS)

Tang Hong; Lin Jianzhong

2011-01-01

The extinction coefficient of atmospheric aerosol particles influences the earth’s radiation balance directly or indirectly, and it can be determined by the scattering and absorption characteristics of aerosol particles. The problem of estimating the change of extinction coefficient due to time evolution of bimodal particle size distribution is studied, and two improved methods for calculating the Brownian coagulation coefficient and the condensation growth rate are proposed, respectively. Through the improved method based on Otto kernel, the Brownian coagulation coefficient can be expressed simply in powers of particle volume for the entire particle size regime based on the fitted polynomials of the mean enhancement function. Meanwhile, the improved method based on Fuchs–Sutugin kernel is developed to obtain the condensation growth rate for the entire particle size regime. And then, the change of the overall extinction coefficient of bimodal distributions undergoing Brownian coagulation and condensation can be estimated comprehensively for the entire particle size regime. Simulation experiments indicate that the extinction coefficients obtained with the improved methods coincide fairly well with the true values, which provide a simple, reliable, and general method to estimate the change of extinction coefficient for the entire particle size regime during the bimodal particle dynamic processes.

Evaluation of Advanced Models for PAFS Condensation Heat Transfer in SPACE Code

Energy Technology Data Exchange (ETDEWEB)

Bae, Byoung-Uhn; Kim, Seok; Park, Yu-Sun; Kang, Kyung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ahn, Tae-Hwan; Yun, Byong-Jo [Pusan National University, Busan (Korea, Republic of)

2015-10-15

The PAFS (Passive Auxiliary Feedwater System) is operated by the natural circulation to remove the core decay heat through the PCHX (Passive Condensation Heat Exchanger) which is composed of the nearly horizontal tubes. For validation of the cooling and operational performance of the PAFS, PASCAL (PAFS Condensing Heat Removal Assessment Loop) facility was constructed and the condensation heat transfer and natural convection phenomena in the PAFS was experimentally investigated at KAERI (Korea Atomic Energy Research Institute). From the PASCAL experimental result, it was found that conventional system analysis code underestimated the condensation heat transfer. In this study, advanced condensation heat transfer models which can treat the heat transfer mechanisms with the different flow regimes in the nearly horizontal heat exchanger tube were analyzed. The models were implemented in a thermal hydraulic safety analysis code, SPACE (Safety and Performance Analysis Code for Nuclear Power Plant), and it was evaluated with the PASCAL experimental data. With an aim of enhancing the prediction capability for the condensation phenomenon inside the PCHX tube of the PAFS, advanced models for the condensation heat transfer were implemented into the wall condensation model of the SPACE code, so that the PASCAL experimental result was utilized to validate the condensation models. Calculation results showed that the improved model for the condensation heat transfer coefficient enhanced the prediction capability of the SPACE code. This result confirms that the mechanistic modeling for the film condensation in the steam phase and the convection in the condensate liquid contributed to enhance the prediction capability of the wall condensation model of the SPACE code and reduce conservatism in prediction of condensation heat transfer.

Improvement of and Parameter Identification for the Bimodal Time-Varying Modified Kanai-Tajimi Power Spectral Model

Directory of Open Access Journals (Sweden)

Huiguo Chen

2017-01-01

Full Text Available Based on the Kanai-Tajimi power spectrum filtering method proposed by Du Xiuli et al., a genetic algorithm and a quadratic optimization identification technique are employed to improve the bimodal time-varying modified Kanai-Tajimi power spectral model and the parameter identification method proposed by Vlachos et al. Additionally, a method for modeling time-varying power spectrum parameters for ground motion is proposed. The 8244 Orion and Chi-Chi earthquake accelerograms are selected as examples for time-varying power spectral model parameter identification and ground motion simulations to verify the feasibility and effectiveness of the improved bimodal time-varying modified Kanai-Tajimi power spectral model. The results of this study provide important references for designing ground motion inputs for seismic analyses of major engineering structures.

A Novel Method of Extraction of Blend Component Structure from SANS Measurements of Homopolymer Bimodal Blends.

Science.gov (United States)

Smerdova, Olga; Graham, Richard S; Gasser, Urs; Hutchings, Lian R; De Focatiis, Davide S A

2014-05-01

A new method is presented for the extraction of single-chain form factors and interchain interference functions from a range of small-angle neutron scattering (SANS) experiments on bimodal homopolymer blends. The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels. The method is validated through an experimental study on polystyrene homopolymer bimodal blends with [Formula: see text]. By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography. The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths. [Formula: see text].

Taking Poseidon's Measure from Space: Advances in our Understanding of the Ocean

Science.gov (United States)

Avery, S. K.

2017-12-01

In many ways the ocean defines our planet and makes it livable. It provides marine resources and ecosystem services that are critical to a sustainable society. Today we understand that there is a growing need to predict, manage, and adapt to changes on our planet - changes that occur not only in the atmosphere but also in the ocean. Over the last 40 years remarkable advances in measuring key ocean quantities have been made - through the development of new satellite technologies and successful missions as well as through in-situ observing systems enabled by advances in robotics, communications, navigation, and sensors. Ocean science (and atmospheric science) is a science of numbers, imaging, and numerical models. Predictability of the ocean is tied to the scale of variability in space and time. Satellite observations have spectacularly showed us the incredible structure and variability of the ocean. It has been the combination of satellites and in-situ sensors that have allowed us to advance understanding and prediction. This presentation will highlight some of the key scientific advances that have been enabled by satellites.

Human mammary epithelial cells exhibit a bimodal correlated random walk pattern.

Science.gov (United States)

Potdar, Alka A; Jeon, Junhwan; Weaver, Alissa M; Quaranta, Vito; Cummings, Peter T

2010-03-10

Organisms, at scales ranging from unicellular to mammals, have been known to exhibit foraging behavior described by random walks whose segments confirm to Lévy or exponential distributions. For the first time, we present evidence that single cells (mammary epithelial cells) that exist in multi-cellular organisms (humans) follow a bimodal correlated random walk (BCRW). Cellular tracks of MCF-10A pBabe, neuN and neuT random migration on 2-D plastic substrates, analyzed using bimodal analysis, were found to reveal the BCRW pattern. We find two types of exponentially distributed correlated flights (corresponding to what we refer to as the directional and re-orientation phases) each having its own correlation between move step-lengths within flights. The exponential distribution of flight lengths was confirmed using different analysis methods (logarithmic binning with normalization, survival frequency plots and maximum likelihood estimation). Because of the presence of non-uniform turn angle distribution of move step-lengths within a flight and two different types of flights, we propose that the epithelial random walk is a BCRW comprising of two alternating modes with varying degree of correlations, rather than a simple persistent random walk. A BCRW model rather than a simple persistent random walk correctly matches the super-diffusivity in the cell migration paths as indicated by simulations based on the BCRW model.

Human mammary epithelial cells exhibit a bimodal correlated random walk pattern.

Directory of Open Access Journals (Sweden)

Alka A Potdar

2010-03-01

Full Text Available Organisms, at scales ranging from unicellular to mammals, have been known to exhibit foraging behavior described by random walks whose segments confirm to Lévy or exponential distributions. For the first time, we present evidence that single cells (mammary epithelial cells that exist in multi-cellular organisms (humans follow a bimodal correlated random walk (BCRW.Cellular tracks of MCF-10A pBabe, neuN and neuT random migration on 2-D plastic substrates, analyzed using bimodal analysis, were found to reveal the BCRW pattern. We find two types of exponentially distributed correlated flights (corresponding to what we refer to as the directional and re-orientation phases each having its own correlation between move step-lengths within flights. The exponential distribution of flight lengths was confirmed using different analysis methods (logarithmic binning with normalization, survival frequency plots and maximum likelihood estimation.Because of the presence of non-uniform turn angle distribution of move step-lengths within a flight and two different types of flights, we propose that the epithelial random walk is a BCRW comprising of two alternating modes with varying degree of correlations, rather than a simple persistent random walk. A BCRW model rather than a simple persistent random walk correctly matches the super-diffusivity in the cell migration paths as indicated by simulations based on the BCRW model.

Automation and robotics for the Space Station - The influence of the Advanced Technology Advisory Committee

Science.gov (United States)

Nunamaker, Robert R.; Willshire, Kelli F.

1988-01-01

The reports of a committee established by Congress to identify specific systems of the Space Station which would advance automation and robotics technologies are reviewed. The history of the committee, its relation to NASA, and the reports which it has released are discussed. The committee's reports recommend the widespread use of automation and robotics for the Space Station, a program for technology development and transfer between industries and research and development communities, and the planned use of robots to service and repair satellites and their payloads which are accessible from the Space Station.

SpaceWire- Based Control System Architecture for the Lightweight Advanced Robotic Arm Demonstrator [LARAD

Science.gov (United States)

Rucinski, Marek; Coates, Adam; Montano, Giuseppe; Allouis, Elie; Jameux, David

2015-09-01

The Lightweight Advanced Robotic Arm Demonstrator (LARAD) is a state-of-the-art, two-meter long robotic arm for planetary surface exploration currently being developed by a UK consortium led by Airbus Defence and Space Ltd under contract to the UK Space Agency (CREST-2 programme). LARAD has a modular design, which allows for experimentation with different electronics and control software. The control system architecture includes the on-board computer, control software and firmware, and the communication infrastructure (e.g. data links, switches) connecting on-board computer(s), sensors, actuators and the end-effector. The purpose of the control system is to operate the arm according to pre-defined performance requirements, monitoring its behaviour in real-time and performing safing/recovery actions in case of faults. This paper reports on the results of a recent study about the feasibility of the development and integration of a novel control system architecture for LARAD fully based on the SpaceWire protocol. The current control system architecture is based on the combination of two communication protocols, Ethernet and CAN. The new SpaceWire-based control system will allow for improved monitoring and telecommanding performance thanks to higher communication data rate, allowing for the adoption of advanced control schemes, potentially based on multiple vision sensors, and for the handling of sophisticated end-effectors that require fine control, such as science payloads or robotic hands.

Recent results from advanced research on space solar cells at NASA

Science.gov (United States)

Flood, Dennis J.

1990-01-01

The NASA program in space photovoltaic research and development encompasses a wide range of emerging options for future space power systems, and includes both cell and array technology development. The long range goals are to develop technology capable of achieving 300 W/kg for planar arrays, and 300 W/sq m for concentrator arrays. InP and GaAs planar and concentrator cell technologies are under investigation for their potential high efficiency and good radiation resistance. The Advanced Photovoltaic Solar Array (APSA) program is a near term effort aimed at demonstrating 130 W/kg beginning of life specific power using thin (62 pm) silicon cells. It is intended to be technology transparent to future high efficiency cells and provides the baseline for development of the 300 W/kg array.

NASA advanced space photovoltaic technology-status, potential and future mission applications

Science.gov (United States)

Flood, Dennis J.; Piszczor, Michael, Jr.; Stella, Paul M.; Bennett, Gary L.

1989-01-01

The NASA program in space photovoltaic research and development encompasses a wide range of emerging options for future space power systems, and includes both cell and array technology development. The long range goals are to develop technology capable of achieving 300 W/kg for planar arrays, and 300 W/sq m for concentrator arrays. InP and GaAs planar and concentrator cell technologies are under investigation for their potential high efficiency and good radiation resistance. The Advanced Photovoltaic Solar Array (APSA) program is a near term effort aimed at demonstrating 130 W/kg beginning of life specific power using thin (62 micrometer) silicon cells. It is intended to be technology transparent to future high efficiency cells and provides the baseline for development of the 300 W/kg array.

Uterosacral space involvement in locally advanced carcinoma of the uterine cervix

International Nuclear Information System (INIS)

Chao, K. S. Clifford; Williamson, Jeffrey F.; Grigsby, Perry W.; Perez, Carlos A.

1998-01-01

Purpose: Radiation therapy is the standard management for locally advanced cervical cancer, but it has not yielded fully satisfactory results; a relatively high incidence of local failure remains. Standard radiation therapy techniques combine external beam radiation and brachytherapy generating a homogeneously composite dose distribution covering the lateral parametria but may not be adequate in the uterosacral and perirectal areas due to the spatial arrangement of intracavitary system and the constraints of rectal tolerance. We hypothesize that these dosimetric characteristics might lead to a higher incidence of central/marginal failures when the uterosacral space is involved by locally advanced carcinoma of uterine cervix. Methods and Materials: Between January 1970 and December 1989, 343 patients with clinical Stage IIIB cervical cancer were treated at the Mallinckrodt Institute of Radiology with radiation therapy alone. We identified 83 patients with clinical evidence of tumor in the uterosacral region; the remaining 260 patients either did not have uterosacral involvement or were unspecified. The dose of external beam irradiation ranged from 18.02 to 33.20 Gy to the central pelvis and 48.22 to 59.40 Gy to the lateral parametrium. The average total dose, including brachytherapy contribution, to point A and the lateral pelvis was 80.30 to 86.46 Gy and 60.50 to 73.40 Gy, respectively. External beam dose to the lateral parametria was, on average, 10 Gy higher in patients with uterosacral involvement. Results: We categorized the patterns of pelvic failure into central/marginal (including medial parametrium) and lateral parametria. The cumulative incidence of central/marginal failure at 5 years was significantly higher in the group of patients with uterosacral involvement (36% compared with 21% for patients without uterosacral involvement or unspecified) (p = 0.002). Lateral parametrial failure was similar for patients with and without uterosacral involvement (39

Biological effects of space radiation on human cells. History, advances and outcomes

International Nuclear Information System (INIS)

Maalouf, M.; Foray, N.; Durante, M.

2011-01-01

Exposure to radiation is one of the main concerns for space exploration by humans. By focusing deliberately on the works performed on human cells, we endeavored to review, decade by decade, the technological developments and conceptual advances of space radiation biology. Despite considerable efforts, the cancer and the toxicity risks remain to be quantified: the nature and the frequency of secondary heavy ions need to be better characterized in order to estimate their contribution to the dose and to the final biological response; the diversity of radiation history of each astronaut and the impact of individual susceptibility make very difficult any epidemiological analysis for estimating hazards specifically due to space radiation exposure. Cytogenetic data undoubtedly revealed that space radiation exposure produce significant damage in cells. However, our knowledge of the basic mechanisms specific to low-dose, to repeated doses and to adaptive response is still poor. The application of new radiobiological techniques, like immunofluorescence, and the use of human tissue models different from blood, like skin fibroblasts, may help in clarifying all the above items. (author)

System modeling for the advanced thermionic initiative single cell thermionic space nuclear reactor

International Nuclear Information System (INIS)

Lee, H.H.; Lewis, B.R.; Klein, A.C.; Pawlowski, R.A.

1993-01-01

Incore thermionic space reactor design concepts which operate in a nominal power output range of 20 to 40 kWe are described. Details of the neutronics, thermionic, shielding, and heat rejection performance are presented. Two different designs, ATI-Driven and ATI-Driverless, are considered. Comparison of the core overall performance of these two configurations are described. The comparison of these two cores includes the overall conversion efficiency, reactor mass, shield mass, and heat rejection mass. An overall system design has been developed to model the advanced incore thermionic energy conversion based nuclear reactor systems for space applications in this power range

A Status of the Advanced Space Transportation Program from Planning to Action

Science.gov (United States)

Lyles, Garry; Griner, Carolyn

1998-01-01

A Technology Plan for Enabling Commercial Space Business was presented at the 48th International Astronautical Congress in Turin, Italy. This paper presents a status of the program's accomplishments. Technology demonstrations have progressed in each of the four elements of the program; (1) Low Cost Technology, (2) Advanced Reusable Technology, (3) Space Transfer Technology and (4) Space Transportation Research. The Low Cost Technology program element is primarily focused at reducing development and acquisition costs of aerospace hardware using a "design to cost" philosophy with robust margins, adapting commercial manufacturing processes and commercial off-the-shelf hardware. The attributes of this philosophy for small payload launch are being demonstrated at the component, sub-system, and system level. The X-34 "Fastrac" engine has progressed through major component and subsystem demonstrations. A propulsion system test bed has been implemented for system-level demonstration of component and subsystem technologies; including propellant tankage and feedlines, controls, pressurization, and engine systems. Low cost turbopump designs, commercial valves and a controller are demonstrating the potential for a ten-fold reduction in engine and propulsion system costs. The Advanced Reusable Technology program element is focused on increasing life through high strength-to-weight structures and propulsion components, highly integrated propellant tanks, automated checkout and health management and increased propulsion system performance. The validation of rocket based combined cycle (RBCC) propulsion is pro,-,ressing through component and subsystem testing. RBCC propulsion has the potential to provide performance margin over an all rocket system that could result in lower gross liftoff weight, a lower propellant mass fraction or a higher payload mass fraction. The Space Transfer Technology element of the program is pursuing technology that can improve performance and

Saturated hydraulic conductivity model computed from bimodal water retention curves for a range of New Zealand soils

Directory of Open Access Journals (Sweden)

J. A. P. Pollacco

2017-06-01

Full Text Available Descriptions of soil hydraulic properties, such as the soil moisture retention curve, θ(h, and saturated hydraulic conductivities, Ks, are a prerequisite for hydrological models. Since the measurement of Ks is expensive, it is frequently derived from statistical pedotransfer functions (PTFs. Because it is usually more difficult to describe Ks than θ(h from pedotransfer functions, Pollacco et al. (2013 developed a physical unimodal model to compute Ks solely from hydraulic parameters derived from the Kosugi θ(h. This unimodal Ks model, which is based on a unimodal Kosugi soil pore-size distribution, was developed by combining the approach of Hagen–Poiseuille with Darcy's law and by introducing three tortuosity parameters. We report here on (1 the suitability of the Pollacco unimodal Ks model to predict Ks for a range of New Zealand soils from the New Zealand soil database (S-map and (2 further adaptations to this model to adapt it to dual-porosity structured soils by computing the soil water flux through a continuous function of an improved bimodal pore-size distribution. The improved bimodal Ks model was tested with a New Zealand data set derived from historical measurements of Ks and θ(h for a range of soils derived from sandstone and siltstone. The Ks data were collected using a small core size of 10 cm diameter, causing large uncertainty in replicate measurements. Predictions of Ks were further improved by distinguishing topsoils from subsoil. Nevertheless, as expected, stratifying the data with soil texture only slightly improved the predictions of the physical Ks models because the Ks model is based on pore-size distribution and the calibrated parameters were obtained within the physically feasible range. The improvements made to the unimodal Ks model by using the new bimodal Ks model are modest when compared to the unimodal model, which is explained by the poor accuracy of measured total porosity. Nevertheless, the new bimodal

Saturated hydraulic conductivity model computed from bimodal water retention curves for a range of New Zealand soils

Science.gov (United States)

Pollacco, Joseph Alexander Paul; Webb, Trevor; McNeill, Stephen; Hu, Wei; Carrick, Sam; Hewitt, Allan; Lilburne, Linda

2017-06-01

Descriptions of soil hydraulic properties, such as the soil moisture retention curve, θ(h), and saturated hydraulic conductivities, Ks, are a prerequisite for hydrological models. Since the measurement of Ks is expensive, it is frequently derived from statistical pedotransfer functions (PTFs). Because it is usually more difficult to describe Ks than θ(h) from pedotransfer functions, Pollacco et al. (2013) developed a physical unimodal model to compute Ks solely from hydraulic parameters derived from the Kosugi θ(h). This unimodal Ks model, which is based on a unimodal Kosugi soil pore-size distribution, was developed by combining the approach of Hagen-Poiseuille with Darcy's law and by introducing three tortuosity parameters. We report here on (1) the suitability of the Pollacco unimodal Ks model to predict Ks for a range of New Zealand soils from the New Zealand soil database (S-map) and (2) further adaptations to this model to adapt it to dual-porosity structured soils by computing the soil water flux through a continuous function of an improved bimodal pore-size distribution. The improved bimodal Ks model was tested with a New Zealand data set derived from historical measurements of Ks and θ(h) for a range of soils derived from sandstone and siltstone. The Ks data were collected using a small core size of 10 cm diameter, causing large uncertainty in replicate measurements. Predictions of Ks were further improved by distinguishing topsoils from subsoil. Nevertheless, as expected, stratifying the data with soil texture only slightly improved the predictions of the physical Ks models because the Ks model is based on pore-size distribution and the calibrated parameters were obtained within the physically feasible range. The improvements made to the unimodal Ks model by using the new bimodal Ks model are modest when compared to the unimodal model, which is explained by the poor accuracy of measured total porosity. Nevertheless, the new bimodal model provides an

Investigation of heterogeneous asymmetric dihydroxylation over OsO{sub 4}-(QN){sub 2}PHAL catalysts of functionalized bimodal mesoporous silica with ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Qiu, Shenjie [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Sun, Jihong, E-mail: jhsun@bjut.edu.cn [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Li, Yuzhen; Gao, Lin [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China)

2011-08-15

Highlights: {yields} Functionalized bimodal mesoporous silica with MTMSPIm{sup +}Cl{sup -}. {yields} Mesoporous catalyst immobilized with OsO{sub 4}-(QN){sub 2}PHAL. {yields} Catalysts for asymmetric dihydroxylation reaction with high yield and enatioselectivity. {yields} Recyclable catalysts. -- Abstract: A novel synthesis of the functionalized bimodal mesoporous silica with ionic liquid (FBMMs) was performed. After grafting 1-methyl-3-(trimethoxysilyl)propylimidazolium chloride onto the surface of bimodal mesoporous silicas, 1,4-bis(9-O-quininyl)phthalazine ((QN){sub 2}-PHAL) and K{sub 2}Os(OH){sub 4}.2H{sub 2}O were immobilized onto the modified FBMMs by adsorption or ionic exchange methods, and then, the asymmetric dihydroxylation reaction was carried out by using solid catalysts. Techniques such as X-ray diffraction, Fourier Transform Infrared spectroscopy, N{sub 2} adsorption and desorption were employed to characterize their structure and properties. The results showed that the mesoporous ordering degree of bimodal mesoporous silica decreased after functionalization and immobilization of OsO{sub 4}-(QN){sub 2}PHAL. Being very effective in asymmetric dihydroxylation with high yield and enantioselectivity, the prepared heterogeneous solid catalyst could be recycled for five times with little loss of enantioselectivity, with comparison of those results obtained in homophase system. Moreover, the effect of Osmium catalyst on asymmetric dihydroxylation was investigated.

Recent developments of advanced structures for space optics at Astrium, Germany

Science.gov (United States)

Stute, Thomas; Wulz, Georg; Scheulen, Dietmar

2003-12-01

The mechanical division of EADS Astrium GmbH, Friedrichshafen Germany, the former Dornier Satellitensystem GmbH is currently engaged with the development, manufacturing and testing of three different advanced dimensionally stable composite and ceramic material structures for satellite borne optics: -CFRP Camera Structure -Planck Telescope Reflectors -NIRSpec Optical Bench Breadboard for James Web Space Telescope The paper gives an overview over the requirements and the main structural features how these requirements are met. Special production aspects and available test results are reported.

A Mobile Communications Space Link Between the Space Shuttle Orbiter and the Advanced Communications Technology Satellite

Science.gov (United States)

Fink, Patrick; Arndt, G. D.; Bondyopadhyay, P.; Shaw, Roland

1994-01-01

A communications experiment is described as a link between the Space Shuttle Orbiter (SSO) and the Advanced Communications Technology Satellite (ACTS). Breadboarding for this experiment has led to two items with potential for commercial application: a 1-Watt Ka-band amplifier and a Ka-band, circularly polarized microstrip antenna. Results of the hybrid Ka-band amplifier show gain at 30 dB and a saturated output power of 28.5 dBm. A second version comprised of MMIC amplifiers is discussed. Test results of the microstrip antenna subarray show a gain of approximately 13 dB and excellent circular polarization.

Surviving the space environment - An overview of advanced materials and structures development at the CWRU CCDS

Science.gov (United States)

Wallace, John F.; Zdankiewicz, Edward M.; Schmidt, Robert N.

1991-01-01

The development of advanced materials and structures for long-term use in space is described with specific reference given to applications to the Space Station Freedom and the lunar base. A flight-testing program is described which incorporates experiments regarding the passive effects of space travel such as material degradation with active materials experiments such as the Materials Exposure Flight Experiment. Also described is a research and development program for materials such as organic coatings and polymeric composites, and a simulation laboratory is described which permits the analysis of materials in the laboratory. The methods of investigation indicate that the NASA Center for the Commercial Development of Space facilitates the understanding of material degradation in space.

Advanced controls for stability assessment of solar dynamics space power generation

Science.gov (United States)

Momoh, James A.; Anwah, Nnamdi A.

1995-01-01

In support of the power requirements for the Space Station Alpha (SSA), a joint program by the U.S. and Russia for a permanently manned space station to be launched into orbit by 1998, a robust control scheme is needed to assure the stability of the rotating machines that will be integrated into the power subsystem. A framework design and systems studies for modeling and analysis is presented. It employs classical d-q axes machine model with voltage/frequency dependent loads. To guarantee that design requirements and necessary trade studies are done, a functional analysis tool CORE is used for the study. This provides us with different control options for stability assessment. Initial studies and recommendations using advanced simulation tools are also presented. The benefits of the stability/control scheme for evaluating future designs and power management are discussed.

Conventional and Bimodal Nuclear Thermal Rocket (NTR) Artificial Gravity Mars Transfer Vehicle Concepts

Science.gov (United States)

Borowski, Stanley K.; McCurdy, David R.; Packard, Thomas W.

2016-01-01

A variety of countermeasures have been developed to address the debilitating physiological effects of zero-gravity (0-g) experienced by cosmonauts and astronauts during their approximately 0.5 to 1.2 year long stays in low Earth orbit (LEO). Longer interplanetary flights, combined with possible prolonged stays in Mars orbit, could subject crewmembers to up to approximately 2.5 years of weightlessness. In view of known and recently diagnosed problems associated with 0-g, an artificial gravity (AG) spacecraft offers many advantages and may indeed be an enabling technology for human flights to Mars. A number of important human factors must be taken into account in selecting the rotation radius, rotation rate, and orientation of the habitation module or modules. These factors include the gravity gradient effect, radial and tangential Coriolis forces, along with cross-coupled acceleration effects. Artificial gravity Mars transfer vehicle (MTV) concepts are presented that utilize both conventional NTR, as well as, enhanced bimodal nuclear thermal rocket (BNTR) propulsion. The NTR is a proven technology that generates high thrust and has a specific impulse (Isp) capability of approximately 900 s-twice that of today's best chemical rockets. The AG/MTV concepts using conventional Nuclear Thermal Propulsion (NTP) carry twin cylindrical International Space Station (ISS)- type habitation modules with their long axes oriented either perpendicular or parallel to the longitudinal spin axis of the MTV and utilize photovoltaic arrays (PVAs) for spacecraft power. The twin habitat modules are connected to a central operations hub located at the front of the MTV via two pressurized tunnels that provide the rotation radius for the habitat modules. For the BNTR AG/MTV option, each engine has its own closed secondary helium(He)-xenon (Xe) gas loop and Brayton Rotating Unit (BRU) that can generate 10s of kilowatts (kWe) of spacecraft electrical power during the mission coast phase

Impact of Bimodal Traffic on Latency in Optical Burst Switching Networks

Directory of Open Access Journals (Sweden)

Yuhua Chen

2008-01-01

Full Text Available This paper analyzes the impact of bimodal traffic composition on latency in optical burst switching networks. In particular, it studies the performance degradation to short-length packets caused by longer packets, both of which are part of a heterogeneous traffic model. The paper defines a customer satisfaction index for each of the classes of traffic, and a composite satisfaction index. The impact of higher overall utilization of the network as well as that of the ratio of the traffic mix on each of the customer satisfaction indices is specifically addressed.

A two stage launch vehicle for use as an advanced space transportation system for logistics support of the space station

Science.gov (United States)

1987-01-01

This report describes the preliminary design specifications for an Advanced Space Transportation System consisting of a fully reusable flyback booster, an intermediate-orbit cargo vehicle, and a shuttle-type orbiter with an enlarged cargo bay. It provides a comprehensive overview of mission profile, aerodynamics, structural design, and cost analyses. These areas are related to the overall feasibility and usefullness of the proposed system.

Advancing automation and robotics technology for the space station and for the US economy: Submitted to the United States Congress May 15, 1987

Science.gov (United States)

1987-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on the space station. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the Law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the fourth in a series of progress updates and covers the period October 1, 1986 to May 15, 1987. NASA has accepted the basic recommendations of ATAC for its space station efforts. ATAC and NASA agree that the will of Congress is to build an advanced automation and robotics technology base that will support an evolutionary space station program and serve as a highly visible stimulator affecting the long-term U.S. economy. The progress report identifies the work of NASA and the space station study contractors, research in progress, and issues connected with the advancement of automation and robotics technology on the space station.

Advancing automation and robotics technology for the space station and for the US economy: Submitted to the United States Congress October 1, 1986

Science.gov (United States)

1986-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committer (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on the space station. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the Law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the third in a series of progress updates and covers the period between April 1, 1986 and September 30, 1986. NASA has accepted the basic recommendations of ATAC for its space station efforts. ATAC and NASA agree that the will of Congress is to build an advanced automation and robotics technology base that will support an evolutionary space station program and serve as a highly visible stimulater affecting the long-term U.S. economy. The progress report identifies the work of NASA and the space station study contractors, research in progress, and issues connected with the advancement of automation and robotics technology on the space station.

The Evolution of Technology in the Deep Space Network: A History of the Advanced Systems Program

Science.gov (United States)

Layland, J. W.; Rauch, L. L.

1994-01-01

The Deep Space Network (DSN) of 1995 might be described as the evolutionary result of 45 years of deep space communication and navigation, together with the synergistic activities of radio science and radar and radio astronomy. But the evolution of the DSN did not just happen - it was carefully planned and created. The evolution of the DSN has been an ongoing engineering activity, and engineering is a process of problem solving under constraints, one of which is technology. In turn, technology is the knowledge base providing the capability and experience for practical application of various areas of science, when needed. The best engineering solutions result from optimization under the fewest constraints, and if technology needs are well anticipated (ready when needed), then the most effective engineering solution is possible. Throughout the history of the DSN it has been the goal and function of DSN advanced technology development (designated the DSN Advanced Systems Program from 1963 through 1994) to supply the technology needs of the DSN when needed, and thus to minimize this constraint on DSN engineering. Technology often takes considerable time to develop, and when that happens, it is important to have anticipated engineering needs; at times, this anticipation has been by as much as 15 years. Also, on a number of occasions, mission malfunctions or emergencies have resulted in unplanned needs for technology that has, in fact, been available from the reservoir of advanced technology provided by the DSN Advanced Systems Program. Sometimes, even DSN engineering personnel fail to realize that the organization of JPL permits an overlap of DSN advanced technology activities with subsequent engineering activities. This can result in the flow of advanced technology into DSN engineering in a natural and sometimes almost unnoticed way. In the following pages, we will explore some of the many contributions of the DSN Advanced Systems Program that were provided to DSN

Advancing automation and robotics technology for the Space Station Freedom and for the US economy: Submitted to the United States Congress

Science.gov (United States)

1990-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on the Space Station Freedom. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the ninth in a series of progress updates and covers the period between February 24, 1989, and July 12, 1989. NASA has accepted the basic recommendation of ATAC for its Space Station Freedom efforts. ATAC and NASA agree that the thrust of Congress is to build an advanced automation and robotics technology base that will support an evolutionary Space Station program and serve as a highly visible stimulator, affecting the U.S. long-term economy. The work of NASA and the Freedom contractors, e.g., Work Packages, as well as the Flight Telerobotic Servicer is identified. Research in progress is also described and assessments of the advancement of automation and robotics technology on the Space Station Freedom are given.

Spatial attention triggered by unimodal, crossmodal, and bimodal exogenous cues: a comparison of reflexive orienting mechanisms

NARCIS (Netherlands)

Santangelo, Valerio; van der Lubbe, Robert Henricus Johannes; Belardinelli, Marta Olivetti; Postma, Albert

The aim of this study was to establish whether spatial attention triggered by bimodal exogenous cues acts differently as compared to unimodal and crossmodal exogenous cues due to crossmodal integration. In order to investigate this issue, we examined cuing effects in discrimination tasks and

The role of martensitic transformation on bimodal grain structure in ultrafine grained AISI 304L stainless steel

International Nuclear Information System (INIS)

Sabooni, S.; Karimzadeh, F.; Enayati, M.H.; Ngan, A.H.W.

2015-01-01

In the present study, metastable AISI 304L austenitic stainless steel samples were subjected to different cold rolling reductions from 70% to 93%, followed by annealing at 700 °C for 300 min to form ultrafine grained (UFG) austenite with different grain structures. Transmission electron microscopy (TEM) and nanoindentation were used to characterize the martensitic transformation, in order to relate it to the bimodal distribution of the austenite grain size after subsequent annealing. The results showed that the martensite morphology changed from lath type in the 60% rolled sample to a mixture of lath and dislocation-cell types in the higher rolling reductions. Calculation of the Gibbs free energy change during the reversion treatment showed that the reversion mechanism is shear controlled at the annealing temperature and so the morphology of the reverted austenite is completely dependent on the morphology of the deformation induced martensite. It was found that the austenite had a bimodal grain size distribution in the 80% rolled and annealed state and this is related to the existence of different types of martensite. Increasing the rolling reduction to 93% followed by annealing caused changing of the grain structure to a monomodal like structure, which was mostly covered with small grains of around 300 nm. The existence of bimodal austenite grain size in the 80% rolled and annealed 304L stainless steel led to the improvement of ductility while maintaining a high tensile strength in comparison with the 93% rolled and annealed sample

The effect of oxide particles on the strength and ductility of bulk iron with a bimodal grain size distribution

Energy Technology Data Exchange (ETDEWEB)

Casas, C.; Tejedor, R. [Department of Materials Science and Metallurgical Engineering, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Rodríguez-baracaldo, R. [Department of Mechanical Engineering, Universidad Nacional de Colombia, Bogotá. Colombia (Colombia); Benito, J.A., E-mail: Josep.a.benito@upc.edu [Department of Materials Science and Metallurgical Engineering, EUETIB, Universitat Politècnica de Catalunya, Comte d' Urgell 187, 08036 Barcelona (Spain); Fundació CTM Centre Tecnològic de Manresa, Plaça de la Ciencia, 2, 08243 Manresa (Spain); Cabrera, J.M. [Department of Materials Science and Metallurgical Engineering, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundació CTM Centre Tecnològic de Manresa, Plaça de la Ciencia, 2, 08243 Manresa (Spain)

2015-03-11

The strength and ductility of bulk nanostructured and ultrafine-grained iron containing 0.39% oxygen by weight was determined by tensile tests. Samples were obtained by consolidation of milled iron powder at 500 °C. Heat treatments were designed to cover a wide range of grain sizes spanning from 100 to 2000 nm with different percentages of coarse and nanostructured grain areas, which was defined as a bimodal grain size distribution. Transmission electron microscopy was used to determine the diameter, volume fraction and location of oxides in the microstructure. The strength was analysed following two approaches. The first one was based on the strong effect of oxides and involved the use of a mixed particle-grain boundary strengthening model, and the second one was based on simple grain boundary strengthening. The mixed model underestimated the strength of nanostructured samples, whereas the simple grain boundary model worked better. However, for specimens with a bimodal grain size, the fitting of the mixed model was better. In this case, the more effective particle strengthening was related to the dispersion of oxides inside the large ferrite grains. In addition, the bimodal samples showed an acceptable combination of strength and ductility. Again, the ferrite grains containing oxides promoted strain hardening due to the increase in dislocation activity.

Rotational multispectral fluorescence lifetime imaging and intravascular ultrasound: bimodal system for intravascular applications

Science.gov (United States)

Ma, Dinglong; Bec, Julien; Yankelevich, Diego R.; Gorpas, Dimitris; Fatakdawala, Hussain; Marcu, Laura

2014-01-01

Abstract. We report the development and validation of a hybrid intravascular diagnostic system combining multispectral fluorescence lifetime imaging (FLIm) and intravascular ultrasound (IVUS) for cardiovascular imaging applications. A prototype FLIm system based on fluorescence pulse sampling technique providing information on artery biochemical composition was integrated with a commercial IVUS system providing information on artery morphology. A customized 3-Fr bimodal catheter combining a rotational side-view fiberoptic and a 40-MHz IVUS transducer was constructed for sequential helical scanning (rotation and pullback) of tubular structures. Validation of this bimodal approach was conducted in pig heart coronary arteries. Spatial resolution, fluorescence detection efficiency, pulse broadening effect, and lifetime measurement variability of the FLIm system were systematically evaluated. Current results show that this system is capable of temporarily resolving the fluorescence emission simultaneously in multiple spectral channels in a single pullback sequence. Accurate measurements of fluorescence decay characteristics from arterial segments can be obtained rapidly (e.g., 20 mm in 5 s), and accurate co-registration of fluorescence and ultrasound features can be achieved. The current finding demonstrates the compatibility of FLIm instrumentation with in vivo clinical investigations and its potential to complement conventional IVUS during catheterization procedures. PMID:24898604

Bimodality in binary Au + Au collisions from 60 to 100 MeV/u

International Nuclear Information System (INIS)

Pichon, M.; Tamain, B.; Bougault, R.

2003-03-01

The deexcitation of quasi-projectiles (QP) released in binary Au on Au collisions as been studied from 60 to 100 MeV/u. Bimodality between two different decay patterns has been observed for intermediate violence collisions. The main experimental result is that the system jumps from one mode to the other on a narrow range of energy deposit and/or impact parameter. The sorting of the events (according to the violence of the collision) has been provided by the perpendicular energy of the light charged particles emitted on the quasi-target side. Such a sorting prevents spurious autocorrelation effects between the sorting variable and the observed mechanism. The two modes of the QP decay correspond on the one side to residue or fission fragments production, and on the other side to the multifragmentation channel. A detailed study has been performed in order to try to establish the origin of the observed bimodality in disentangling dynamical or geometrical effects from bulk matter properties linked with a liquid-gas type phase transition. The whole set of data is coherent with a dominant role of the deposited excitation energy as it is expected from theoretical arguments.(lattice gas model) in the framework of a liquid-gas phase transition picture. (authors)

Inversion of multiwavelength Raman lidar data for retrieval of bimodal aerosol size distribution

Science.gov (United States)

Veselovskii, Igor; Kolgotin, Alexei; Griaznov, Vadim; Müller, Detlef; Franke, Kathleen; Whiteman, David N.

2004-02-01

We report on the feasibility of deriving microphysical parameters of bimodal particle size distributions from Mie-Raman lidar based on a triple Nd:YAG laser. Such an instrument provides backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm. The inversion method employed is Tikhonov's inversion with regularization. Special attention has been paid to extend the particle size range for which this inversion scheme works to ~10 μm, which makes this algorithm applicable to large particles, e.g., investigations concerning the hygroscopic growth of aerosols. Simulations showed that surface area, volume concentration, and effective radius are derived to an accuracy of ~50% for a variety of bimodal particle size distributions. For particle size distributions with an effective radius of rims along which anthropogenic pollution mixes with marine aerosols. Measurement cases obtained from the Institute for Tropospheric Research six-wavelength aerosol lidar observations during the Indian Ocean Experiment were used to test the capabilities of the algorithm for experimental data sets. A benchmark test was attempted for the case representing anthropogenic aerosols between a broken cloud deck. A strong contribution of particle volume in the coarse mode of the particle size distribution was found.

Preparation of bimodal grain size 7075 aviation aluminum alloys and their corrosion properties

Directory of Open Access Journals (Sweden)

Wenming TIAN

2017-10-01

Full Text Available The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bimodal grain size 7075 aviation aluminum alloys containing different ratios of coarse (100 μm in diameter and fine (10 μm in diameter grains were prepared by spark plasma sintering (SPS. The effects of grain size as well as the mixture degree of coarse and fine grains on general corrosion were estimated by immersion tests, electrochemical measurements and complementary techniques such as scanning electron microscope (SEM and transmission electron microscope-energy disperse spectroscopy (TEM-EDS. The results show that, compared to fine grains, the coarse grains have a faster dissolution rate in acidic NaCl solution due to the bigger size, higher alloying elements content and larger area fraction of second phases in them. In coarse grains, the hydrogen ions have a faster reduction rate on cathodic second phases, therefore promoting the corrosion propagation. The mixture of coarse and fine grains also increases the electrochemical heterogeneity of alloys in micro-scale, and thus the increased mixture degree of these grains in metal matrix accelerates the corrosion rate of alloys in acidic NaCl solution.

Advanced Health Management System for the Space Shuttle Main Engine

Science.gov (United States)

Davidson, Matt; Stephens, John; Rodela, Chris

2006-01-01

Pratt & Whitney Rocketdyne, Inc., in cooperation with NASA-Marshall Space Flight Center (MSFC), has developed a new Advanced Health Management System (AHMS) controller for the Space Shuttle Main Engine (SSME) that will increase the probability of successfully placing the shuttle into the intended orbit and increase the safety of the Space Transportation System (STS) launches. The AHMS is an upgrade o the current Block II engine controller whose primary component is an improved vibration monitoring system called the Real-Time Vibration Monitoring System (RTVMS) that can effectively and reliably monitor the state of the high pressure turbomachinery and provide engine protection through a new synchronous vibration redline which enables engine shutdown if the vibration exceeds predetermined thresholds. The introduction of this system required improvements and modification to the Block II controller such as redesigning the Digital Computer Unit (DCU) memory and the Flight Accelerometer Safety Cut-Off System (FASCOS) circuitry, eliminating the existing memory retention batteries, installation of the Digital Signal Processor (DSP) technology, and installation of a High Speed Serial Interface (HSSI) with accompanying outside world connectors. Test stand hot-fire testing along with lab testing have verified successful implementation and is expected to reduce the probability of catastrophic engine failures during the shuttle ascent phase and improve safely by about 23% according to the Quantitative Risk Assessment System (QRAS), leading to a safer and more reliable SSME.

Advanced Space Suit Portable Life Support Subsystem Packaging Design

Science.gov (United States)

Howe, Robert; Diep, Chuong; Barnett, Bob; Thomas, Gretchen; Rouen, Michael; Kobus, Jack

2006-01-01

This paper discusses the Portable Life Support Subsystem (PLSS) packaging design work done by the NASA and Hamilton Sundstrand in support of the 3 future space missions; Lunar, Mars and zero-g. The goal is to seek ways to reduce the weight of PLSS packaging, and at the same time, develop a packaging scheme that would make PLSS technology changes less costly than the current packaging methods. This study builds on the results of NASA s in-house 1998 study, which resulted in the "Flex PLSS" concept. For this study the present EMU schematic (low earth orbit) was used so that the work team could concentrate on the packaging. The Flex PLSS packaging is required to: protect, connect, and hold the PLSS and its components together internally and externally while providing access to PLSS components internally for maintenance and for technology change without extensive redesign impact. The goal of this study was two fold: 1. Bring the advanced space suit integrated Flex PLSS concept from its current state of development to a preliminary design level and build a proof of concept mockup of the proposed design, and; 2. "Design" a Design Process, which accommodates both the initial Flex PLSS design and the package modifications, required to accommodate new technology.

Specialized data analysis for the Space Shuttle Main Engine and diagnostic evaluation of advanced propulsion system components

Science.gov (United States)

1993-01-01

The Marshall Space Flight Center is responsible for the development and management of advanced launch vehicle propulsion systems, including the Space Shuttle Main Engine (SSME), which is presently operational, and the Space Transportation Main Engine (STME) under development. The SSME's provide high performance within stringent constraints on size, weight, and reliability. Based on operational experience, continuous design improvement is in progress to enhance system durability and reliability. Specialized data analysis and interpretation is required in support of SSME and advanced propulsion system diagnostic evaluations. Comprehensive evaluation of the dynamic measurements obtained from test and flight operations is necessary to provide timely assessment of the vibrational characteristics indicating the operational status of turbomachinery and other critical engine components. Efficient performance of this effort is critical due to the significant impact of dynamic evaluation results on ground test and launch schedules, and requires direct familiarity with SSME and derivative systems, test data acquisition, and diagnostic software. Detailed analysis and evaluation of dynamic measurements obtained during SSME and advanced system ground test and flight operations was performed including analytical/statistical assessment of component dynamic behavior, and the development and implementation of analytical/statistical models to efficiently define nominal component dynamic characteristics, detect anomalous behavior, and assess machinery operational condition. In addition, the SSME and J-2 data will be applied to develop vibroacoustic environments for advanced propulsion system components, as required. This study will provide timely assessment of engine component operational status, identify probable causes of malfunction, and indicate feasible engineering solutions. This contract will be performed through accomplishment of negotiated task orders.

Elaboration of austenitic stainless steel samples with bimodal grain size distributions and investigation of their mechanical behavior

Science.gov (United States)

Flipon, B.; de la Cruz, L. Garcia; Hug, E.; Keller, C.; Barbe, F.

2017-10-01

Samples of 316L austenitic stainless steel with bimodal grain size distributions are elaborated using two distinct routes. The first one is based on powder metallurgy using spark plasma sintering of two powders with different particle sizes. The second route applies the reverse-annealing method: it consists in inducing martensitic phase transformation by plastic strain and further annealing in order to obtain two austenitic grain populations with different sizes. Microstructural analy ses reveal that both methods are suitable to generate significative grain size contrast and to control this contrast according to the elaboration conditions. Mechanical properties under tension are then characterized for different grain size distributions. Crystal plasticity finite element modelling is further applied in a configuration of bimodal distribution to analyse the role played by coarse grains within a matrix of fine grains, considering not only their volume fraction but also their spatial arrangement.

Status of the Space-Rated Lithium-Ion Battery Advanced Development Project in Support of the Exploration Vision

Science.gov (United States)

Miller, Thomas

2007-01-01

The NASA Glenn Research Center (GRC), along with the Goddard Space Flight Center (GSFC), Jet Propulsion Laboratory (JPL), Johnson Space Center (JSC), Marshall Space Flight Center (MSFC), and industry partners, is leading a space-rated lithium-ion advanced development battery effort to support the vision for Exploration. This effort addresses the lithium-ion battery portion of the Energy Storage Project under the Exploration Technology Development Program. Key discussions focus on the lithium-ion cell component development activities, a common lithium-ion battery module, test and demonstration of charge/discharge cycle life performance and safety characterization. A review of the space-rated lithium-ion battery project will be presented highlighting the technical accomplishments during the past year.

A bio-inspired, microchanneled hydrogel with controlled spacing of cell adhesion ligands regulates 3D spatial organization of cells and tissue.

Science.gov (United States)

Lee, Min Kyung; Rich, Max H; Lee, Jonghwi; Kong, Hyunjoon

2015-07-01

Bioactive hydrogels have been extensively studied as a platform for 3D cell culture and tissue regeneration. One of the key desired design parameters is the ability to control spatial organization of biomolecules and cells and subsequent tissue in a 3D matrix. To this end, this study presents a simple but advanced method to spatially organize microchanneled, cell adherent gel blocks and non-adherent ones in a single construct. This hydrogel system was prepared by first fabricating a bimodal hydrogel in which the microscale, alginate gel blocks modified with cell adhesion peptides containing Arg-Gly-Asp sequence (RGD peptides), and those free of RGD peptides, were alternatingly presented. Then, anisotropically aligned microchannels were introduced by uniaxial freeze-drying of the bimodal hydrogel. The resulting gel system could drive bone marrow stromal cells to adhere to and differentiate into neuron and glial cells exclusively in microchannels of the alginate gel blocks modified with RGD peptides. Separately, the bimodal gel loaded with microparticles releasing vascular endothelial growth factor stimulated vascular growth solely into microchannels of the RGD-alginate gel blocks in vivo. These results were not attained by the bimodal hydrogel fabricated to present randomly oriented micropores. Overall, the bimodal gel system could regulate spatial organization of nerve-like tissue or blood vessels at sub-micrometer length scale. We believe that the hydrogel assembly demonstrated in this study will be highly useful in developing a better understanding of diverse cellular behaviors in 3D tissue and further improve quality of a wide array of engineered tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

Knowledge Engineering Aspects of Affective Bi-Modal Educational Applications

Science.gov (United States)

Alepis, Efthymios; Virvou, Maria; Kabassi, Katerina

This paper analyses the knowledge and software engineering aspects of educational applications that provide affective bi-modal human-computer interaction. For this purpose, a system that provides affective interaction based on evidence from two different modes has been developed. More specifically, the system's inferences about students' emotions are based on user input evidence from the keyboard and the microphone. Evidence from these two modes is combined by a user modelling component that incorporates user stereotypes as well as a multi criteria decision making theory. The mechanism that integrates the inferences from the two modes has been based on the results of two empirical studies that were conducted in the context of knowledge engineering of the system. The evaluation of the developed system showed significant improvements in the recognition of the emotional states of users.

Advanced free space optics (FSO) a systems approach

CERN Document Server

Majumdar, Arun K

2015-01-01

This book provides a comprehensive, unified tutorial covering the most recent advances in the technology of free-space optics (FSO). It is an all-inclusive source of information on the fundamentals of FSO as well as up-to-date information on the state-of-the-art in technologies available today. This text is intended for graduate students, and will also be useful for research scientists and engineers with an interest in the field. FSO communication is a practical solution for creating a three dimensional global broadband communications grid, offering bandwidths far beyond what is possible in the Radio Frequency (RF) range. However, the attributes of atmospheric turbulence and scattering impose perennial limitations on availability and reliability of FSO links. From a systems point-of-view, this groundbreaking book provides a thorough understanding of channel behavior, which can be used to design and evaluate optimum transmission techniques that operate under realistic atmospheric conditions. Topics addressed...

Nanophotonic lab-on-a-chip platforms including novel bimodal interferometers, microfluidics and grating couplers.

Science.gov (United States)

Duval, Daphné; González-Guerrero, Ana Belén; Dante, Stefania; Osmond, Johann; Monge, Rosa; Fernández, Luis J; Zinoviev, Kirill E; Domínguez, Carlos; Lechuga, Laura M

2012-05-08

One of the main limitations for achieving truly lab-on-a-chip (LOC) devices for point-of-care diagnosis is the incorporation of the "on-chip" detection. Indeed, most of the state-of-the-art LOC devices usually require complex read-out instrumentation, losing the main advantages of portability and simplicity. In this context, we present our last advances towards the achievement of a portable and label-free LOC platform with highly sensitive "on-chip" detection by using nanophotonic biosensors. Bimodal waveguide interferometers fabricated by standard silicon processes have been integrated with sub-micronic grating couplers for efficient light in-coupling, showing a phase resolution of 6.6 × 10(-4)× 2π rad and a limit of detection of 3.3 × 10(-7) refractive index unit (RIU) in bulk. A 3D network of SU-8 polymer microfluidics monolithically assembled at the wafer-level was included, ensuring perfect sealing and compact packaging. To overcome some of the drawbacks inherent to interferometric read-outs, a novel all-optical wavelength modulation system has been implemented, providing a linear response and a direct read-out of the phase variation. Sensitivity, specificity and reproducibility of the wavelength modulated BiMW sensor has been demonstrated through the label-free immunodetection of the human hormone hTSH at picomolar level using a reliable biofunctionalization process.

Space Station technology testbed: 2010 deep space transport

Science.gov (United States)

Holt, Alan C.

1993-01-01

A space station in a crew-tended or permanently crewed configuration will provide major R&D opportunities for innovative, technology and materials development and advanced space systems testing. A space station should be designed with the basic infrastructure elements required to grow into a major systems technology testbed. This space-based technology testbed can and should be used to support the development of technologies required to expand our utilization of near-Earth space, the Moon and the Earth-to-Jupiter region of the Solar System. Space station support of advanced technology and materials development will result in new techniques for high priority scientific research and the knowledge and R&D base needed for the development of major, new commercial product thrusts. To illustrate the technology testbed potential of a space station and to point the way to a bold, innovative approach to advanced space systems' development, a hypothetical deep space transport development and test plan is described. Key deep space transport R&D activities are described would lead to the readiness certification of an advanced, reusable interplanetary transport capable of supporting eight crewmembers or more. With the support of a focused and highly motivated, multi-agency ground R&D program, a deep space transport of this type could be assembled and tested by 2010. Key R&D activities on a space station would include: (1) experimental research investigating the microgravity assisted, restructuring of micro-engineered, materials (to develop and verify the in-space and in-situ 'tuning' of materials for use in debris and radiation shielding and other protective systems), (2) exposure of microengineered materials to the space environment for passive and operational performance tests (to develop in-situ maintenance and repair techniques and to support the development, enhancement, and implementation of protective systems, data and bio-processing systems, and virtual reality and

Experimental study of the Fermi–Pasta–Ulam recurrence in a bi-modal electrical transmission line

International Nuclear Information System (INIS)

Farota, Abdou K; Faye, Mansour M

2013-01-01

We report on the experimental observation of the Fermi–Pasta–Ulam (FPU) recurrence in an experimental bi-modal nonlinear transmission line. The FPU recurrence is observed in the two transmission modes known as the low frequency mode and the high frequency mode. In each case, a spectrum analysis is performed in order to study the waves along the line. (paper)

Fast, High Resolution, and Wide Modulus Range Nanomechanical Mapping with Bimodal Tapping Mode.

Science.gov (United States)

Kocun, Marta; Labuda, Aleksander; Meinhold, Waiman; Revenko, Irène; Proksch, Roger

2017-10-24

Tapping mode atomic force microscopy (AFM), also known as amplitude modulated (AM) or AC mode, is a proven, reliable, and gentle imaging mode with widespread applications. Over the several decades that tapping mode has been in use, quantification of tip-sample mechanical properties such as stiffness has remained elusive. Bimodal tapping mode keeps the advantages of single-frequency tapping mode while extending the technique by driving and measuring an additional resonant mode of the cantilever. The simultaneously measured observables of this additional resonance provide the additional information necessary to extract quantitative nanomechanical information about the tip-sample mechanics. Specifically, driving the higher cantilever resonance in a frequency modulated (FM) mode allows direct measurement of the tip-sample interaction stiffness and, with appropriate modeling, the set point-independent local elastic modulus. Here we discuss the advantages of bimodal tapping, coined AM-FM imaging, for modulus mapping. Results are presented for samples over a wide modulus range, from a compliant gel (∼100 MPa) to stiff materials (∼100 GPa), with the same type of cantilever. We also show high-resolution (subnanometer) stiffness mapping of individual molecules in semicrystalline polymers and of DNA in fluid. Combined with the ability to remain quantitative even at line scan rates of nearly 40 Hz, the results demonstrate the versatility of AM-FM imaging for nanomechanical characterization in a wide range of applications.

Utterance independent bimodal emotion recognition in spontaneous communication

Science.gov (United States)

Tao, Jianhua; Pan, Shifeng; Yang, Minghao; Li, Ya; Mu, Kaihui; Che, Jianfeng

2011-12-01

Emotion expressions sometimes are mixed with the utterance expression in spontaneous face-to-face communication, which makes difficulties for emotion recognition. This article introduces the methods of reducing the utterance influences in visual parameters for the audio-visual-based emotion recognition. The audio and visual channels are first combined under a Multistream Hidden Markov Model (MHMM). Then, the utterance reduction is finished by finding the residual between the real visual parameters and the outputs of the utterance related visual parameters. This article introduces the Fused Hidden Markov Model Inversion method which is trained in the neutral expressed audio-visual corpus to solve the problem. To reduce the computing complexity the inversion model is further simplified to a Gaussian Mixture Model (GMM) mapping. Compared with traditional bimodal emotion recognition methods (e.g., SVM, CART, Boosting), the utterance reduction method can give better results of emotion recognition. The experiments also show the effectiveness of our emotion recognition system when it was used in a live environment.

NASA University Research Centers Technical Advances in Education, Aeronautics, Space, Autonomy, Earth and Environment

Science.gov (United States)

Jamshidi, M. (Editor); Lumia, R. (Editor); Tunstel, E., Jr. (Editor); White, B. (Editor); Malone, J. (Editor); Sakimoto, P. (Editor)

1997-01-01

This first volume of the Autonomous Control Engineering (ACE) Center Press Series on NASA University Research Center's (URC's) Advanced Technologies on Space Exploration and National Service constitute a report on the research papers and presentations delivered by NASA Installations and industry and Report of the NASA's fourteen URC's held at the First National Conference in Albuquerque, New Mexico from February 16-19, 1997.

Low Energy Reaction cell for advanced space power applications

International Nuclear Information System (INIS)

Miley, George H.; Rice, Eric

2001-01-01

Power units using Low Energy Reactions (LENRs) are under study as a radical new approach to power units that could potentially replace nuclear and chemical power sources for a number of space applications. These cells employ thin metallic films (order of 500 deg., using variously Ni, Pd and Ti) as cathodes with various electrolytes such as 0.5-1 molar lithium sulfate in light water. Power densities exceeding 10 W/cm3 in the thin-films have been achieved. An ultimate goal is to incorporate this thin-film technology into a 'tightly packed' cell design where the film material occupies ∼20% of the total cell volume. If this is achieved, overall power densities of ∼20 W/cm3 appear feasible, opening the way to a number of potential applications ranging from distributed power units in spacecraft to advanced propulsion

Non-Gaussian theory of rubberlike elasticity based on rotational isomeric state simulations of network chain configurations. II. Bimodal poly(dimethylsiloxane) networks

International Nuclear Information System (INIS)

Curro, J.G.; Mark, J.E.

1984-01-01

Bimodal, poly(dimethylsiloxane) (PDMS) networks containing a large mole fraction of very short chains have been shown to be unusually tough elastomers. The purpose of this investigation is to understand the rubber elasticity behavior of these bimodal networks. As a first approach, we have assumed that the average chain deformation is affine. This deformation, however, is partitioned nonaffinely between the long and short chains so that the free energy is minimized. Gaussian statistics are used for the long chains. The distribution function for the short chains is found from Monte Carlo calculations. This model predicts an upturn in the stress-strain curve, the steepness depending on the network composition, as is observed experimentally

Fabrication and imaging study of ultrasound/fluorescence bi-modal contrast agent based on polymeric microbubbles

International Nuclear Information System (INIS)

Xing Zhanwen; Ke Hengte; Wang Jinrui; Zhao Bo; Qu Enze; Yue Xiuli; Dai Zhifei

2013-01-01

Objective: To fabricate an ultrasound/fluorescence bi-modal contrast agent by encapsulating fluorescent quantum dots into polymeric ultrasound contrast agent microbubbles. Methods: Polylactic acid (PLA, 500 mg), (1R)-(+)-camphor (50 mg) and CdSe/ZnS quantum dots (0.5 ml, 2.3 μmol/L)were dissolved or dispersed in dichloromethane (10 ml) to form in an organic phase. Ammonium carbonate solution and poly (vinyl alcohol) solution were employed as the internal and external water phase, respectively. The fluorescent microbubbles were generated using double emulsion solvent evaporation and lyophilization methods. The morphology and illumination were characterized by scanning electron microscopy (SEM) and fluorescence spectrophotometry. Synchronized contrast-enhanced ultrasound and fluorescence imaging was acquired by injecting fluorescent microbubbles into the silicone tube coupled to a self-made ultrasound/fluorescence imaging device. Ultrasound/fluorescence bi-modal in vivo imaging was acquired on the kidney of New Zealand rabbits and suckling mice. Results: The fluorescent microbubbles were hollow spheres with an averaged diameter of (1.62 ± 1.47) μm. More than 99% of these microbubbles were less than 8 μm in diameter, which met the size criteria for ultrasound contrast agents. The fluorescence emission peak of the microbubbles appeared at 632 nm, indicating that good luminescence properties of quantum dots were maintained. In vitro ultrasound/fluorescence imaging showed no echoic signal when the silicone tube was filled with saline, but there was a strong echo when filled with fluorescent microbubbles. The liquid column with fluorescent microbubbles emitted red luminescence under ultraviolet irradiation. The kidney of the rabbit was remarkably enhanced after the administration of fluorescent microbubbles. Bright fluorescence could be observed at the injection site of the suckling mice via subcutaneous injection. Conclusions: A bi-modal but single contrast agent

A bimodal temom model for particle Brownian coagulation in the continuum-slip regime

Directory of Open Access Journals (Sweden)

He Qing

2016-01-01

Full Text Available In this paper, a bimodal Taylor-series expansion moment of method is proposed to deal with Brownian coagulation in the continuum-slip regime, where the non-linear terms in the Cunningham correction factor is approximated by Taylor-series expansion technology. The results show that both the number concentration and volume fraction decrease with time in the smaller mode due to the intra and inter coagulation, and the asymptotic behavior of the larger mode is as same as that in the continuum regime.

Advanced UVOIR Mirror Technology Development (AMTD) for Very Large Space Telescopes

Science.gov (United States)

Stahl, H. Philip; Smith, W. Scott; Mosier, Gary; Abplanalp, Laura; Arnold, William

2014-01-01

ASTRO2010 Decadal stated that an advanced large-aperture ultraviolet, optical, near-infrared (UVOIR) telescope is required to enable the next generation of compelling astrophysics and exoplanet science; and, that present technology is not mature enough to affordably build and launch any potential UVOIR mission concept. AMTD builds on the state of art (SOA) defined by over 30 years of monolithic & segmented ground & space-telescope mirror technology to mature six key technologies. AMTD is deliberately pursuing multiple design paths to provide the science community with op-tions to enable either large aperture monolithic or segmented mirrors with clear engineering metrics traceable to science requirements.

Concept design and cluster control of advanced space connectable intelligent microsatellite

Science.gov (United States)

Wang, Xiaohui; Li, Shuang; She, Yuchen

2017-12-01

In this note, a new type of advanced space connectable intelligent microsatellite is presented to extend the range of potential application of microsatellite and improve the efficiency of cooperation. First, the overall concept of the micro satellite cluster is described, which is characterized by autonomously connecting with each other and being able to realize relative rotation through the external interfaces. Second, the multi-satellite autonomous assembly algorithm and control algorithm of the cluster motion are developed to make the cluster system combine into a variety of configurations in order to achieve different types of functionality. Finally, the design of the satellite cluster system is proposed, and the possible applications are discussed.

Advancing automation and robotics technology for the Space Station Freedom and for the U.S. economy. Submitted to the Congress of the U.S. May 1991

Science.gov (United States)

Lum, Henry, Jr.

1991-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on Space Station Freedom. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the law was that ATAC follow NASA's progress in this area and report to Congress semiannually. The report describes the progress made by Levels 1, 2 and 3 of the Office Space Station in developing and applying advanced automation and robotics technology. Emphasis has been placed upon the Space Station Freedom Program responses to specific recommendations made in ATAC Progress Report 11, the status of the Flight Telerobotic Servicer, and the status of the Advanced Development Program. In addition, an assessment is provided of the automation and robotics status of the Canadian Space Station Program.

Advanced automation for in-space vehicle processing

Science.gov (United States)

Sklar, Michael; Wegerif, D.

1990-01-01

The primary objective of this 3-year planned study is to assure that the fully evolved Space Station Freedom (SSF) can support automated processing of exploratory mission vehicles. Current study assessments show that required extravehicular activity (EVA) and to some extent intravehicular activity (IVA) manpower requirements for required processing tasks far exceeds the available manpower. Furthermore, many processing tasks are either hazardous operations or they exceed EVA capability. Thus, automation is essential for SSF transportation node functionality. Here, advanced automation represents the replacement of human performed tasks beyond the planned baseline automated tasks. Both physical tasks such as manipulation, assembly and actuation, and cognitive tasks such as visual inspection, monitoring and diagnosis, and task planning are considered. During this first year of activity both the Phobos/Gateway Mars Expedition and Lunar Evolution missions proposed by the Office of Exploration have been evaluated. A methodology for choosing optimal tasks to be automated has been developed. Processing tasks for both missions have been ranked on the basis of automation potential. The underlying concept in evaluating and describing processing tasks has been the use of a common set of 'Primitive' task descriptions. Primitive or standard tasks have been developed both for manual or crew processing and automated machine processing.

Polymers for bimodal immunoradiotherapy - are they able to promote immune system?

International Nuclear Information System (INIS)

Loukotova, L.; Kucka, J.; Rabyk, M.; Hoecherl, A.; Venclikova, K.; Janouskova, O.; Konefal, R.; Stepanek, P.; Hruby, M.; Kolarova, V.; Sefc, L.

2017-01-01

The conceptually new bimodal treatment is demonstrated with radiolabeled thermoresponsive β-glucan-graft-poly(2- isopropyl-2-oxazoline-co-2-butyl-2-oxazoline). The thermoresponsive polymer behavior in aqueous solutions has been studied showing appropriate cloud point temperature. The in vitro studies have been performed, the polymer has been found to be non-toxic and actively uptaken by cancer cells and macrophages. Moreover, oxidative burst assay has shown the immunostimulatory properties of prepared polymer. The polymer has been radiolabeled with 90 Y 3+ and used in antitumor efficiency in vivo experiment on mice bearing EL4 lymphoma. The in vivo experiment demonstrates the synergic effect of immunoradiotherapy compared to only immunotherapy and radiotherapy. (authors)

Integration of advanced teleoperation technologies for control of space robots

Science.gov (United States)

Stagnaro, Michael J.

1993-01-01

Teleoperated robots require one or more humans to control actuators, mechanisms, and other robot equipment given feedback from onboard sensors. To accomplish this task, the human or humans require some form of control station. Desirable features of such a control station include operation by a single human, comfort, and natural human interfaces (visual, audio, motion, tactile, etc.). These interfaces should work to maximize performance of the human/robot system by streamlining the link between human brain and robot equipment. This paper describes development of a control station testbed with the characteristics described above. Initially, this testbed will be used to control two teleoperated robots. Features of the robots include anthropomorphic mechanisms, slaving to the testbed, and delivery of sensory feedback to the testbed. The testbed will make use of technologies such as helmet mounted displays, voice recognition, and exoskeleton masters. It will allow tor integration and testing of emerging telepresence technologies along with techniques for coping with control link time delays. Systems developed from this testbed could be applied to ground control of space based robots. During man-tended operations, the Space Station Freedom may benefit from ground control of IVA or EVA robots with science or maintenance tasks. Planetary exploration may also find advanced teleoperation systems to be very useful.

Space Technology Mission Directorate Game Changing Development Program FY2015 Annual Program Review: Advanced Manufacturing Technology

Science.gov (United States)

Vickers, John; Fikes, John

2015-01-01

The Advance Manufacturing Technology (AMT) Project supports multiple activities within the Administration's National Manufacturing Initiative. A key component of the Initiative is the Advanced Manufacturing National Program Office (AMNPO), which includes participation from all federal agencies involved in U.S. manufacturing. In support of the AMNPO the AMT Project supports building and Growing the National Network for Manufacturing Innovation through a public-private partnership designed to help the industrial community accelerate manufacturing innovation. Integration with other projects/programs and partnerships: STMD (Space Technology Mission Directorate), HEOMD, other Centers; Industry, Academia; OGA's (e.g., DOD, DOE, DOC, USDA, NASA, NSF); Office of Science and Technology Policy, NIST Advanced Manufacturing Program Office; Generate insight within NASA and cross-agency for technology development priorities and investments. Technology Infusion Plan: PC; Potential customer infusion (TDM, HEOMD, SMD, OGA, Industry); Leverage; Collaborate with other Agencies, Industry and Academia; NASA roadmap. Initiatives include: Advanced Near Net Shape Technology Integrally Stiffened Cylinder Process Development (launch vehicles, sounding rockets); Materials Genome; Low Cost Upper Stage-Class Propulsion; Additive Construction with Mobile Emplacement (ACME); National Center for Advanced Manufacturing.

Overview of NASA's Space Solar Power Technology Advanced Research and Development Program

Science.gov (United States)

Howell, Joe; Mankins, John C.; Davis, N. Jan (Technical Monitor)

2001-01-01

Large solar power satellite (SPS) systems that might provide base load power into terrestrial markets were examined extensively in the 1970s by the US Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA). Following a hiatus of about 15 years, the subject of space solar power (SSP) was reexamined by NASA from 1995-1997 in the 'fresh look' study, and during 1998 in an SSP 'concept definition study', and during 1999-2000 in the SSP Exploratory Research and Technology (SERT) program. As a result of these efforts, during 2001, NASA has initiated the SSP Technology Advanced Research and Development (STAR-Dev) program based on informed decisions. The goal of the STAR-Dev program is to conduct preliminary strategic technology research and development to enable large, multi-megawatt to gigawatt-class space solar power (SSP) systems and wireless power transmission (WPT) for government missions and commercial markets (in-space and terrestrial). Specific objectives include: (1) Release a NASA Research Announcement (NRA) for SSP Projects; (2) Conduct systems studies; (3) Develop Component Technologies; (4) Develop Ground and Flight demonstration systems; and (5) Assess and/or Initiate Partnerships. Accomplishing these objectives will allow informed future decisions regarding further SSP and related research and development investments by both NASA management and prospective external partners. In particular, accomplishing these objectives will also guide further definition of SSP and related technology roadmaps including performance objectives, resources and schedules; including 'multi-purpose' applications (commercial, science, and other government).

Effects of tensile test parameters on the mechanical properties of a bimodal Al–Mg alloy

International Nuclear Information System (INIS)

Magee, Andrew; Ladani, Leila; Topping, Troy D.; Lavernia, Enrique J.

2012-01-01

The properties of aluminum alloy (AA) 5083 are shown to be significantly improved by grain size reduction through cryomilling and the incorporation of unmilled Al particles into the material, creating a bimodal grain size distribution consisting of coarse grains in a nanocrystalline matrix. To provide insight into the mechanical behavior and ultimately facilitate engineering applications, the present study reports on the effects of coarse grain ratio, anisotropy, strain rate and specimen size on the elastic–plastic behavior of bimodal AA 5083 evaluated in uniaxial tension tests using a full-factorial experiment design. To determine the governing failure mechanisms under different testing conditions, the specimens’ failure surfaces were analyzed using optical and electron microscopy. The results of the tests were found to conform to Joshi’s plasticity model. Significant anisotropy effects were observed, in a drastic reduction in strength and ductility, when tension was applied perpendicular (transverse) to the direction of extrusion. These specimens also exhibited a smooth, flat fracture surface morphology with a significantly different surface texture than specimens tested in the axial direction. It was found that decreasing specimen thickness and strain rate served to increase both the strength and ductility of the material. The failure surface morphology was found to differ between specimens of different thicknesses.

Space Sciences Focus Area

Energy Technology Data Exchange (ETDEWEB)

Reeves, Geoffrey D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-08-10

To advance our understanding of the space environment (from the Sun to the Earth and beyond) and to advance our ability to operate systems in space that protect life and society. Space Science is distinct from other field, such as astrophysics or cosmology, in that Space Science utilizes in-situ measurements from high altitude rockets, balloons and spacecraft or ground-based measurements of objects and conditions in space.

Biodiesel production from transesterification of palm oil with methanol over CaO supported on bimodal meso-macroporous silica catalyst.

Science.gov (United States)

Witoon, Thongthai; Bumrungsalee, Sittisut; Vathavanichkul, Peerawut; Palitsakun, Supaphorn; Saisriyoot, Maythee; Faungnawakij, Kajornsak

2014-03-01

Calcium oxide-loaded porous materials have shown promise as catalysts in transesterification. However, the slow diffusion of bulky triglycerides through the pores limited the activity of calcium oxide (CaO). In this work, bimodal meso-macroporous silica was used as a support to enhance the accessibility of the CaO dispersed inside the pores. Unimodal porous silica having the identical mesopore diameter was employed for the purpose of comparison. Effects of CaO content and catalyst pellet size on the yield of fatty acid methyl esters (FAME) were investigated. The basic strength was found to increase with increasing the CaO content. The CaO-loaded bimodal porous silica catalyst with the pellet size of 325μm achieved a high %FAME of 94.15 in the first cycle, and retained an excellent %FAME of 88.87 after five consecutive cycles. Copyright © 2014 Elsevier Ltd. All rights reserved.

Topology Optimization and Robotic Fabrication of Advanced Timber Space-frame Structures

DEFF Research Database (Denmark)

Søndergaard, Asbjørn; Amir, Oded; Eversmann, Phillip

2016-01-01

This paper presents a novel method for integrated topology optimization and fabrication of advanced timber space-frame structures. The method, developed in research collaboration between ETH Zürich, Aarhus School of Architecture and Israel Institute of Technology, entails the coupling of truss...... processes solving timber joint intersections, robotically controlling member prefabrication, and spatial robotic assembly of the optimized timber structures. The implication of this concept is studied through pilot fabrication and load-testing of a full scale prototype structure.......-based topology optimization with digital procedures for rationalization and robotic assembly of bespoke timber members, through a procedural, cross-application workflow. Through this, a direct chaining of optimization and robotic fabrication is established, in which optimization data is driving subsequent...

Space Commercialization

Science.gov (United States)

Martin, Gary L.

2011-01-01

A robust and competitive commercial space sector is vital to continued progress in space. The United States is committed to encouraging and facilitating the growth of a U.S. commercial space sector that supports U.S. needs, is globally competitive, and advances U.S. leadership in the generation of new markets and innovation-driven entrepreneurship. Energize competitive domestic industries to participate in global markets and advance the development of: satellite manufacturing; satellite-based services; space launch; terrestrial applications; and increased entrepreneurship. Purchase and use commercial space capabilities and services to the maximum practical extent Actively explore the use of inventive, nontraditional arrangements for acquiring commercial space goods and services to meet United States Government requirements, including measures such as public-private partnerships, . Refrain from conducting United States Government space activities that preclude, discourage, or compete with U.S. commercial space activities. Pursue potential opportunities for transferring routine, operational space functions to the commercial space sector where beneficial and cost-effective.

Advancing automation and robotics technology for the space station and for the US economy: Submitted to the United States Congress October 1, 1987

Science.gov (United States)

1987-01-01

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on the space station. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the Law was that ATAC follow NASA's progress in this area and report to Congress semiannually. This report is the fifth in a series of progress updates and covers the period between 16 May 1987 and 30 September 1987. NASA has accepted the basic recommendations of ATAC for its space station efforts. ATAC and NASA agree that the mandate of Congress is that an advanced automation and robotics technology be built to support an evolutionary space station program and serve as a highly visible stimulator affecting the long-term U.S. economy.

Bimodal gate-dielectric deposition for improved performance of AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors

International Nuclear Information System (INIS)

Pang Liang; Kim, Kyekyoon

2012-01-01

A bimodal deposition scheme combining radiofrequency magnetron sputtering and plasma enhanced chemical vapour deposition (PECVD) is proposed as a means for improving the performance of GaN-based metal-oxide-semiconductor high-electron-mobility transistors (MOSHEMTs). High-density sputtered-SiO 2 is utilized to reduce the gate leakage current and enhance the breakdown voltage while low-density PECVD-SiO 2 is employed to buffer the sputtering damage and further increase the drain current by engineering the stress-induced-polarization. Thus-fabricated MOSHEMT exhibited a low leakage current of 4.21 × 10 -9 A mm -1 and high breakdown voltage of 634 V for a gate-drain distance of 6 µm, demonstrating the promise of bimodal-SiO 2 deposition scheme for the development of GaN-based MOSHEMTs for high-power application. (paper)

Bimodal nature in low-energy fission of light actinides

International Nuclear Information System (INIS)

Nagame, Yuichiro; Nishinaka, Ichiro; Tsukada, Kazuaki; Ikezoe, Hiroshi; Otsuki, Tsutomu; Sueki, Keisuke; Nakahara, Hiromichi; Kudo, Hisaaki.

1995-01-01

To solve various problems in the mass division process of light actinoids, some experiments on the basis of bimodal fission were carried. Mass and kinetic energy distribution of Th-232 and U-238 were determined. Pa-225 (N= 134) and Pa-227 (N=136), fission nuclei, were produced by Bi-209 + 0-16 and Bi-209 + 0-18 heavy ion nucleus reactions, and the mass yield distribution were determined by the time-of-flight method and the radiochemical procedure. From the results, two independent deforming processes were proved in the fission process of light actinoid nuclei. On the deforming process through the low fission barrier, nucleus fissioned after small deformation under the influence of stabilization of the shell structure of fission product. In the case of process through the high barrier, however, the nucleus fissioned after large deformation. The unsymmetrical mass division was derived from the former and the symmetrical one from the latter. (S.Y.)

Intelligent agents: adaptation of autonomous bimodal microsystems

Science.gov (United States)

Smith, Patrice; Terry, Theodore B.

2014-03-01

Autonomous bimodal microsystems exhibiting survivability behaviors and characteristics are able to adapt dynamically in any given environment. Equipped with a background blending exoskeleton it will have the capability to stealthily detect and observe a self-chosen viewing area while exercising some measurable form of selfpreservation by either flying or crawling away from a potential adversary. The robotic agent in this capacity activates a walk-fly algorithm, which uses a built in multi-sensor processing and navigation subsystem or algorithm for visual guidance and best walk-fly path trajectory to evade capture or annihilation. The research detailed in this paper describes the theoretical walk-fly algorithm, which broadens the scope of spatial and temporal learning, locomotion, and navigational performances based on optical flow signals necessary for flight dynamics and walking stabilities. By observing a fly's travel and avoidance behaviors; and, understanding the reverse bioengineering research efforts of others, we were able to conceptualize an algorithm, which works in conjunction with decisionmaking functions, sensory processing, and sensorimotor integration. Our findings suggest that this highly complex decentralized algorithm promotes inflight or terrain travel mobile stability which is highly suitable for nonaggressive micro platforms supporting search and rescue (SAR), and chemical and explosive detection (CED) purposes; a necessity in turbulent, non-violent structured or unstructured environments.

X-ray diffraction microstructural analysis of bimodal size distribution MgO nano powder

International Nuclear Information System (INIS)

Suminar Pratapa; Budi Hartono

2009-01-01

Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500 degree Celsius and 1200 degree Celsius for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then blended in air to give the presumably bimodal-size- distribution MgO nano powder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (R) of 20(1) nm and 160(1) nm for the 500 degree Celsius and 1200 degree Celsius data respectively with the nano metric powder displays narrower crystallite size distribution character, indicated by lognormal dispersion parameter of 0.21 as compared to 0.01 for the sub-nano metric powder. The mixture exhibits relatively more asymmetric peak broadening. Analysing the x-ray diffraction data for the latter specimen using single phase approach give unrealistic results. Introducing two phase models for the double-phase mixture to accommodate the bimodal-size-distribution characteristics give R = 100(6) and σ = 0.62 for the nano metric phase and R = 170(5) and σ= 0.12 for the σ sub-nano metric phase. (author)

First results from the IllustrisTNG simulations: the galaxy colour bimodality

Science.gov (United States)

Nelson, Dylan; Pillepich, Annalisa; Springel, Volker; Weinberger, Rainer; Hernquist, Lars; Pakmor, Rüdiger; Genel, Shy; Torrey, Paul; Vogelsberger, Mark; Kauffmann, Guinevere; Marinacci, Federico; Naiman, Jill

2018-03-01

We introduce the first two simulations of the IllustrisTNG project, a next generation of cosmological magnetohydrodynamical simulations, focusing on the optical colours of galaxies. We explore TNG100, a rerun of the original Illustris box, and TNG300, which includes 2 × 25003 resolution elements in a volume 20 times larger. Here, we present first results on the galaxy colour bimodality at low redshift. Accounting for the attenuation of stellar light by dust, we compare the simulated (g - r) colours of 109 1011 M⊙ which redden at z z = 0 mass post-reddening; at the same time, ˜18 per cent of such massive galaxies acquire half or more of their final stellar mass while on the red sequence.

Bimodal height distribution of self-assembled germanium islands grown on Si0.84Ge0.16 pseudo-substrates

DEFF Research Database (Denmark)

Pedersen, Erik Vesterlund; Jensen, Flemming; Shiryaev, Sergey Y.

1998-01-01

We have investigated the size distribution of germanium islands deposited onto a Si0.84Ge0.16 buffer layer, by atomic force microscopy. The size distribution was found to be bimodal at 630-740 degrees C and consisted of one group of smaller 'pyramidal' islands with a broad distribution of diameters...

THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z {approx}< 1

Energy Technology Data Exchange (ETDEWEB)

Lehner, N.; Howk, J. C. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Tripp, T. M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Tumlinson, J.; Thom, C.; Fox, A. J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Prochaska, J. X.; Werk, J. K. [UCO/Lick Observatory, University of California, Santa Cruz, CA (United States); O' Meara, J. M. [Department of Physics, Saint Michael' s College, Vermont, One Winooski Park, Colchester, VT 05439 (United States); Ribaudo, J. [Department of Physics, Utica College, 1600 Burrstone Road, Utica, New York 13502 (United States)

2013-06-20

We assess the metal content of the cool ({approx}10{sup 4} K) circumgalactic medium (CGM) about galaxies at z {approx}< 1 using an H I-selected sample of 28 Lyman limit systems (LLS; defined here as absorbers with 16.2 {approx}< log N{sub H{sub I}} {approx}< 18.5) observed in absorption against background QSOs by the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The N{sub H{sub I}} selection avoids metallicity biases inherent in many previous studies of the low-redshift CGM. We compare the column densities of weakly ionized metal species (e.g., O II, Si II, Mg II) to N{sub H{sub I}} in the strongest H I component of each absorber. We find that the metallicity distribution of the LLS (and hence the cool CGM) is bimodal with metal-poor and metal-rich branches peaking at [X/H] {approx_equal} -1.6 and -0.3 (or about 2.5% and 50% solar metallicities). The cool CGM probed by these LLS is predominantly ionized. The metal-rich branch of the population likely traces winds, recycled outflows, and tidally stripped gas; the metal-poor branch has properties consistent with cold accretion streams thought to be a major source of fresh gas for star forming galaxies. Both branches have a nearly equal number of absorbers. Our results thus demonstrate there is a significant mass of previously undiscovered cold metal-poor gas and confirm the presence of metal enriched gas in the CGM of z {approx}< 1 galaxies.

The Impact of Bimodal Bilingual Parental Input on the Communication and Language Development of a Young Deaf Child

Science.gov (United States)

Levesque, Elizabeth; Brown, P. Margaret; Wigglesworth, Gillian

2014-01-01

This study explores the impact of bimodal bilingual parental input on the communication and language development of a young deaf child. The participants in this case study were a severe-to-profoundly deaf boy and his hearing parents, who were enrolled in a bilingual (English and Australian Sign Language) homebased early intervention programme. The…

Modality-specific effects on crosstalk in task switching: evidence from modality compatibility using bimodal stimulation.

Science.gov (United States)

Stephan, Denise Nadine; Koch, Iring

2016-11-01

The present study was aimed at examining modality-specific influences in task switching. To this end, participants switched either between modality compatible tasks (auditory-vocal and visual-manual) or incompatible spatial discrimination tasks (auditory-manual and visual-vocal). In addition, auditory and visual stimuli were presented simultaneously (i.e., bimodally) in each trial, so that selective attention was required to process the task-relevant stimulus. The inclusion of bimodal stimuli enabled us to assess congruence effects as a converging measure of increased between-task interference. The tasks followed a pre-instructed sequence of double alternations (AABB), so that no explicit task cues were required. The results show that switching between two modality incompatible tasks increases both switch costs and congruence effects compared to switching between two modality compatible tasks. The finding of increased congruence effects in modality incompatible tasks supports our explanation in terms of ideomotor "backward" linkages between anticipated response effects and the stimuli that called for this response in the first place. According to this generalized ideomotor idea, the modality match between response effects and stimuli would prime selection of a response in the compatible modality. This priming would cause increased difficulties to ignore the competing stimulus and hence increases the congruence effect. Moreover, performance would be hindered when switching between modality incompatible tasks and facilitated when switching between modality compatible tasks.

Weight and cost forecasting for advanced manned space vehicles

Science.gov (United States)

Williams, Raymond

1989-01-01

A mass and cost estimating computerized methology for predicting advanced manned space vehicle weights and costs was developed. The user friendly methology designated MERCER (Mass Estimating Relationship/Cost Estimating Relationship) organizes the predictive process according to major vehicle subsystem levels. Design, development, test, evaluation, and flight hardware cost forecasting is treated by the study. This methodology consists of a complete set of mass estimating relationships (MERs) which serve as the control components for the model and cost estimating relationships (CERs) which use MER output as input. To develop this model, numerous MER and CER studies were surveyed and modified where required. Additionally, relationships were regressed from raw data to accommodate the methology. The models and formulations which estimated the cost of historical vehicles to within 20 percent of the actual cost were selected. The result of the research, along with components of the MERCER Program, are reported. On the basis of the analysis, the following conclusions were established: (1) The cost of a spacecraft is best estimated by summing the cost of individual subsystems; (2) No one cost equation can be used for forecasting the cost of all spacecraft; (3) Spacecraft cost is highly correlated with its mass; (4) No study surveyed contained sufficient formulations to autonomously forecast the cost and weight of the entire advanced manned vehicle spacecraft program; (5) No user friendly program was found that linked MERs with CERs to produce spacecraft cost; and (6) The group accumulation weight estimation method (summing the estimated weights of the various subsystems) proved to be a useful method for finding total weight and cost of a spacecraft.

Thermohydraulic Design Analysis Modeling for Korea Advanced NUclear Thermal Engine Rocket for Space Application

Energy Technology Data Exchange (ETDEWEB)

Nam, Seung Hyun; Choi, Jae Young; Venneria, Paolo F.; Jeong, Yong Hoon; Chang, Soon Heung [KAIST, Daejeon (Korea, Republic of)

2015-05-15

NTR engines have continued as a main stream based on the mature technology. The typical core design of the NERVA derived engines uses hexagonal shaped fuel elements with circular cooling channels and structural tie-tube elements for supporting the fuel elements, housing moderator and regeneratively cooling the moderator. The state-of-the-art NTR designs mostly use a fast or epithermal neutron spectrum core utilizing a HEU fuel to make a high power reactor with small and simple core geometry. Nuclear propulsion is the most promising and viable option to achieve challenging deep space missions. Particularly, the attractions of a NTR include excellent thrust and propellant efficiency, bimodal capability, proven technology, and safe and reliable performance. The KANUTER-HEU and -LEU are the innovative and futuristic NTR engines to reduce the reactor size and to implement a LEU fuel in the reactor by using thermal neutron spectrum. The KANUTERs have some features in the reactor design such as the integrated fuel element and the regeneratively cooling channels to increase room for moderator and heat transfer in the core, and ensuing rocket performance. To study feasible design points in terms of thermo-hydraulics and to estimate rocket performance of the KANUTERs, the NSES is under development. The model of the NSES currently focuses on thermo-hydraulic analysis of the peculiar and complex EHTGR design during the propulsion mode in steady-state. The results indicate comparable performance for future applications, even though it uses the heavier LEU fuel. In future, the NSES will be modified to obtain temperature distribution of the entire reactor components and then more extensive design analysis of neutronics, thermohydraulics and their coupling will be conducted to validate design feasibility and to optimize the reactor design enhancing the rocket performance.

8 Meter Advanced Technology Large-Aperture Space Telescope (ATLAST-8m)

Science.gov (United States)

Stahl, H. Philip

2010-01-01

ATLAST-8m (Advanced Technology Large Aperture Space Telescope) is a proposed 8-meter monolithic UV/optical/NIR space observatory (wavelength range 110 to 2500 nm) to be placed in orbit at Sun-Earth L2 by NASA's planned Ares V heavy lift vehicle. Given its very high angular resolution (15 mas @ 500 nm), sensitivity and performance stability, ATLAST-8m is capable of achieving breakthroughs in a broad range of astrophysics including: Is there life elsewhere in the Galaxy? An 8-meter UVOIR observatory has the performance required to detect habitability (H2O, atmospheric column density) and biosignatures (O2, O3, CH4) in terrestrial exoplanet atmospheres, to reveal the underlying physics that drives star formation, and to trace the complex interactions between dark matter, galaxies, and intergalactic medium. The ATLAST Astrophysics Strategic Mission Concept Study developed a detailed point design for an 8-m monolithic observatory including optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; mass and power budgets; and system cost. The results of which were submitted by invitation to NRC's 2010 Astronomy & Astrophysics Decadal Survey.

Value of bimodal (18)F-choline-PET/MRI and trimodal (18)F-choline-PET/MRI/TRUS for the assessment of prostate cancer recurrence after radiation therapy and radical prostatectomy.

Science.gov (United States)

Paparo, Francesco; Piccardo, Arnoldo; Bacigalupo, Lorenzo; Romagnoli, Andrea; Piccazzo, Riccardo; Monticone, Michela; Cevasco, Luca; Campodonico, Fabio; Conzi, Giuseppe Maria; Carmignani, Giorgio; Rollandi, Gian Andrea

2015-08-01

Between 27% and 53% of all patients who undergo radical prostatectomy (RP) or radiation therapy (RT) as the first-line treatment of prostate cancer (PCa) develop a biochemical recurrence. Imaging plays a pivotal role in restaging by helping to distinguish between local relapse and metastatic disease (i.e., lymph-node and skeletal metastases). At present, the most promising tools for assessing PCa patients with biochemical recurrence are multiparametric magnetic resonance imaging (mpMRI) and positron emission tomography (PET)/computed tomography (CT) with radio-labeled choline derivatives. The main advantage of mpMRI is its high diagnostic accuracy in detecting local recurrence, while choline-PET/CT is able to identify lymph-node metastases when they are not suspicious on morphological imaging. The most recent advances in the field of fusion imaging have shown that multimodal co-registration, synchronized navigation, and combined interpretation are more valuable than the individual; separate assessment offered by different diagnostic techniques. The objective of the present essay was to describe the value of bimodal choline-PET/mpMRI fusion imaging and trimodal choline-PET/mpMRI/transrectal ultrasound (TRUS) in the assessment of PCa recurrence after RP and RT. Bimodal choline-PET/mpMRI fusion imaging allows morphological, functional, and metabolic information to be combined, thereby overcoming the limitations of each separate imaging modality. In addition, trimodal real-time choline-PET/mpMRI/TRUS fusion imaging may be useful for the planning and real-time guidance of biopsy procedures in order to obtain histological confirmation of the local recurrence.

Convenient synthesis of (68)Ga-labeled gadolinium(III) complexes:towards bimodal responsive probes for functional imaging with PET/MRI

OpenAIRE

Notni, Johannes; Hermann, Petr; Dregely, Isabel; Wester, Hans-Jürgen

2013-01-01

A killer application? Recently, fully integrated full-body positron-emission tomography (PET) and magnetic-resonance imaging (MRI) scanners were brought to market, allowing simultaneous recording of complementary 3D data sets. By using bimodal PET/MRI probes (see figure), in vivo 3D mapping of various parameters with medical relevance could become feasible.

The Space Nuclear Thermal Propulsion Program: Propulsion for the twenty first century

International Nuclear Information System (INIS)

Bleeker, G.; Moody, J.; Kesaree, M.

1993-01-01

As mission requirements approach the limits of the chemical propulsion systems, new engines must be investigated that can meet the advanced mission requirements of higher payload fractions, higher velocities, and consequently higher specific Impulses (Isp). The propulsion system that can meet these high demands is a nuclear thermal rocket engine. This engine generates the thrust by expanding/existing the hydrogen, heated from the energy derived from the fission process in a reactor, through a nozzle. The Department of Defense (DoD), however, initiated a new nuclear rocket development program in 1987 for ballistic missile defense application. The Space Nuclear Thermal Propulsion (SNTP) Program that seeks to improve on the technology of ROVER/NERVA grew out of this beginning and has been managed by the Air Force, with the involvement of DoE and NASA. The goal of the SNTP Program is to develop an engine to meet potential Air Force requirements for upper stage engine, bimodal propulsion/power applications, and orbital transfer vehicles, as well as the NASA requirements for possible missions to the Moon and Mars. During the entire life of the program, the DoD has considered safety to be of paramount importance, and is following all national environmental policies

Nonlinear Color–Metallicity Relations of Globular Clusters. VII. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of NGC 5128 Globular Clusters

Energy Technology Data Exchange (ETDEWEB)

Kim, Sooyoung; Yoon, Suk-Jin, E-mail: sjyoon0691@yonsei.ac.kr [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

2017-07-01

Spectroscopy on the globular cluster (GC) system of NGC 5128 revealed bimodality in absorption-line index distributions of its old GCs. GC division is a widely observed and studied phenomenon whose interpretation has depicted host galaxy formation and evolution such that it harbors two distinct metallicity groups. Such a conventional view of GC bimodality has mainly been based on photometry. The recent GC photometric data, however, presented an alternative perspective in which the nonlinear metallicity-to-color transformation is responsible for color bimodality of GC systems. Here we apply the same line of analysis to the spectral indices and examine the absorption-line index versus metallicity relations for the NGC 5128 GC system. NGC 5128 GCs display nonlinearity in the metallicity-index planes, most prominently for the Balmer lines and by a non-negligible degree for the metallicity-sensitive magnesium line. We demonstrate that the observed spectroscopic division of NGC 5128 GCs can be caused by the nonlinear nature of the metallicity-to-index conversions and thus one does not need to resort to two separate GC subgroups. Our analysis incorporating this nonlinearity provides a new perspective on the structure of NGC 5128's GC system, and a further piece to the global picture of the formation of GC systems and their host galaxies.

Vehicle and Mission Design Options for the Human Exploration of Mars/Phobos Using "Bimodal" NTR and LANTR Propulsion

Science.gov (United States)

Borowski, Stanley K.; Dudzinski, Leonard A.; McGuire, Melissa L.

2002-12-01

The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars because of its high specific impulse (1sp is approximately 850-1000 s) capability and its attractive engine thrust-to-weight ratio (approximately 3-10). To stay within the available mass and payload volume limits of a "Magnum" heavy lift vehicle, a high performance propulsion system is required for trans-Mars injection (TMI). An expendable TMI stage, powered by three 15 thousand pounds force (klbf) NTR engines is currently under consideration by NASA for its Design Reference Mission (DRM). However, because of the miniscule burnup of enriched uranium-235 during the Earth departure phase (approximately 10 grams out of 33 kilograms in each NTR core), disposal of the TMI stage and its engines after a single use is a costly and inefficient use of this high performance stage. By reconfiguring the engines for both propulsive thrust and modest power generation (referred to as "bimodal" operation), a robust, multiple burn, "power-rich" stage with propulsive Mars capture and reuse capability is possible. A family of modular bimodal NTR (BNTR) vehicles are described which utilize a common "core" stage powered by three 15 klbf BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration / reliquification system for long term, zero-boiloff liquid hydrogen (LH2) storage, and high data rate communications. An innovative, spine-like "saddle truss" design connects the core stage and payload element and is open underneath to allow supplemental "in-line" propellant tanks and contingency crew consumables to be easily jettisoned to improve vehicle performance. A "modified" DRM using BNTR transfer vehicles requires fewer transportation system elements, reduces IMLEO and mission risk, and simplifies space operations. By taking the next logical step--use of the BNTR for propulsive capture of all payload elements into Mars orbit--the power

Bimodal distribution of damage morphology generated by ion implantation

International Nuclear Information System (INIS)

Mok, K.R.C.; Jaraiz, M.; Martin-Bragado, I.; Rubio, J.E.; Castrillo, P.; Pinacho, R.; Srinivasan, M.P.; Benistant, F.

2005-01-01

A nucleation and evolution model of damage based on amorphous pockets (APs) has recently been developed and implemented in an atomistic kinetic Monte Carlo simulator. In the model, APs are disordered structures (I n V m ), which are agglomerates of interstitials (I) and vacancies (V). This model has been used to study the composition and size distribution of APs during different ion implantations. Depending strongly on the dose rate, ion mass and implant temperature, the APs can evolve to a defect population where the agglomerates have a similar number of I and V (n ∼ m), or to a defect population with pure I (m ∼ 0) and pure V (n ∼ 0) clusters, or a mixture of APs and clusters. This behaviour corresponds to a bimodal (APs/clusters) distribution of damage. As the AP have different thermal stability compared to the I and V clusters, the same damage concentration obtained through different implant conditions has a different damage morphology and, consequently, exhibit a different resistance to subsequent thermal treatments

Advances in single- and multi-stage Stirling-type pulse tube cryocoolers for space applications in NLIP/SITP/CAS

Science.gov (United States)

Dang, Haizheng; Tan, Jun; Zha, Rui; Li, Jiaqi; Zhang, Lei; Zhao, Yibo; Gao, Zhiqian; Bao, Dingli; Li, Ning; Zhang, Tao; Zhao, Yongjiang; Zhao, Bangjian

2017-12-01

This paper presents a review of recent advances in single- and multi-stage Stirling-type pulse tube cryocoolers (SPTCs) for space applications developed at the National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (NLIP/SITP/CAS). A variety of single-stage SPTCs operating at 25-150 K have been developed, including several mid-sized ones operating at 80-110 K. Significant progress has been achieved in coolers operating at 30-40 K which use common stainless steel meshes as regenerator matrices. Another important advance is the micro SPTCs with an overall mass of 300-800 g operating at high frequencies varying from 100 Hz to 400 Hz. The main purpose of developing two-stage SPTCs is to simultaneously acquire cooling capacities at both stages, obviating the need for auxiliary precooling in various applications. The three-stage SPTCs are developed mainly for applications at around 10 K, which are also used for precooling the J-T coolers to achieve further lower temperatures. The four-stage SPTCs are developed to directly achieve the liquid helium temperature for cooling space low-Tc superconducting devices and for the deep space exploration as well. Several typical development programs are described and an overview of the cooler performances is presented.

Modeling the Hydrological Cycle in the Atmosphere of Mars: Influence of a Bimodal Size Distribution of Aerosol Nucleation Particles

Science.gov (United States)

Shaposhnikov, Dmitry S.; Rodin, Alexander V.; Medvedev, Alexander S.; Fedorova, Anna A.; Kuroda, Takeshi; Hartogh, Paul

2018-02-01

We present a new implementation of the hydrological cycle scheme into a general circulation model of the Martian atmosphere. The model includes a semi-Lagrangian transport scheme for water vapor and ice and accounts for microphysics of phase transitions between them. The hydrological scheme includes processes of saturation, nucleation, particle growth, sublimation, and sedimentation under the assumption of a variable size distribution. The scheme has been implemented into the Max Planck Institute Martian general circulation model and tested assuming monomodal and bimodal lognormal distributions of ice condensation nuclei. We present a comparison of the simulated annual variations, horizontal and vertical distributions of water vapor, and ice clouds with the available observations from instruments on board Mars orbiters. The accounting for bimodality of aerosol particle distribution improves the simulations of the annual hydrological cycle, including predicted ice clouds mass, opacity, number density, and particle radii. The increased number density and lower nucleation rates bring the simulated cloud opacities closer to observations. Simulations show a weak effect of the excess of small aerosol particles on the simulated water vapor distributions.

A new insight into high-strength Ti62Nb12.2Fe13.6Co6.4Al5.8 alloys with bimodal microstructure fabricated by semi-solid sintering.

Science.gov (United States)

Liu, L H; Yang, C; Kang, L M; Qu, S G; Li, X Q; Zhang, W W; Chen, W P; Li, Y Y; Li, P J; Zhang, L C

2016-03-31

It is well known that semi-solid forming could only obtain coarse-grained microstructure in a few alloy systems with a low melting point, such as aluminum and magnesium alloys. This work presents that semi-solid forming could also produce novel bimodal microstructure composed of nanostructured matrix and micro-sized (CoFe)Ti2 twins in a titanium alloy, Ti62Nb12.2Fe13.6Co6.4Al5.8. The semi-solid sintering induced by eutectic transformation to form a bimodal microstructure in Ti62Nb12.2Fe13.6Co6.4Al5.8 alloy is a fundamentally different approach from other known methods. The fabricated alloy exhibits high yield strength of 1790 MPa and plastic strain of 15.5%. The novel idea provides a new insight into obtaining nano-grain or bimodal microstructure in alloy systems with high melting point by semi-solid forming and into fabricating high-performance metallic alloys in structural applications.

An advanced regulator for the helium pressurization systems of the Space Shuttle OMS and RCS

Science.gov (United States)

Wichmann, H.

1973-01-01

The Space Shuttle Orbit Maneuvering System and Reaction Control System are pressure-fed rocket propulsion systems utilizing earth storable hypergolic propellants and featuring engines of 6000 lbs and 900 lbs thrust, respectively. The helium pressurization system requirements for these propulsion systems are defined and the current baseline pressurization systems are described. An advanced helium pressure regulator capable of meeting both OMS and RCS helium pressurization system requirements is presented and its operating characteristics and predicted performance characteristics are discussed.

Bimodal atomic force microscopy driving the higher eigenmode in frequency-modulation mode: Implementation, advantages, disadvantages and comparison to the open-loop case.

Science.gov (United States)

Ebeling, Daniel; Solares, Santiago D

2013-01-01

We present an overview of the bimodal amplitude-frequency-modulation (AM-FM) imaging mode of atomic force microscopy (AFM), whereby the fundamental eigenmode is driven by using the amplitude-modulation technique (AM-AFM) while a higher eigenmode is driven by using either the constant-excitation or the constant-amplitude variant of the frequency-modulation (FM-AFM) technique. We also offer a comparison to the original bimodal AFM method, in which the higher eigenmode is driven with constant frequency and constant excitation amplitude. General as well as particular characteristics of the different driving schemes are highlighted from theoretical and experimental points of view, revealing the advantages and disadvantages of each. This study provides information and guidelines that can be useful in selecting the most appropriate operation mode to characterize different samples in the most efficient and reliable way.

Development of Iron Doped Silicon Nanoparticles as Bimodal Imaging Agents

Science.gov (United States)

Singh, Mani P.; Atkins, Tonya M.; Muthuswamy, Elayaraja; Kamali, Saeed; Tu, Chuqiao; Louie, Angelique Y.; Kauzlarich, Susan M.

2012-01-01

We demonstrate the synthesis of water-soluble allylamine terminated Fe doped Si (SixFe) nanoparticles as bimodal agents for optical and magnetic imaging. The preparation involves the synthesis of a single source iron containing precursor, Na4Si4 with x% Fe (x = 1, 5, 10), and its subsequent reaction with NH4Br to produce hydrogen terminated SixFe nanoparticles. The hydrogen-capped nanoparticles are further terminated with allylamine via thermal hydrosilylation. Transmission electron microscopy (TEM) indicates that the average particle diameter is ~3.0±1.0 nm. The Si5Fe nanoparticles show strong photoluminescence quantum yield in water (~ 10 %) with significant T2 contrast (r2/r1value of 4.31). Electron paramagnetic resonance (EPR) and Mössbauer spectroscopies indicate that iron in the nanoparticles is in the +3 oxidation state. Analysis of cytotoxicity using the resazurin assay on HepG2 liver cells indicates that the particles have minimal toxicity. PMID:22616623

Bilingualism alters brain functional connectivity between "control" regions and "language" regions: Evidence from bimodal bilinguals.

Science.gov (United States)

Li, Le; Abutalebi, Jubin; Zou, Lijuan; Yan, Xin; Liu, Lanfang; Feng, Xiaoxia; Wang, Ruiming; Guo, Taomei; Ding, Guosheng

2015-05-01

Previous neuroimaging studies have revealed that bilingualism induces both structural and functional neuroplasticity in the dorsal anterior cingulate cortex (dACC) and the left caudate nucleus (LCN), both of which are associated with cognitive control. Since these "control" regions should work together with other language regions during language processing, we hypothesized that bilingualism may also alter the functional interaction between the dACC/LCN and language regions. Here we tested this hypothesis by exploring the functional connectivity (FC) in bimodal bilinguals and monolinguals using functional MRI when they either performed a picture naming task with spoken language or were in resting state. We found that for bimodal bilinguals who use spoken and sign languages, the FC of the dACC with regions involved in spoken language (e.g. the left superior temporal gyrus) was stronger in performing the task, but weaker in the resting state as compared to monolinguals. For the LCN, its intrinsic FC with sign language regions including the left inferior temporo-occipital part and right inferior and superior parietal lobules was increased in the bilinguals. These results demonstrate that bilingual experience may alter the brain functional interaction between "control" regions and "language" regions. For different control regions, the FC alters in different ways. The findings also deepen our understanding of the functional roles of the dACC and LCN in language processing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Space Elevators: Building a Permanent Bridge for Space Exploration and Economic Development

Science.gov (United States)

Smitherman, David V., Jr.; Howell, Joe T. (Technical Monitor)

2000-01-01

A space elevator is a physical connection from the surface of the Earth to a geo-stationary orbit above the Earth approximately 35,786 km in altitude. Its center of mass is at the geo-stationary point such that it has a 24-hour orbit, and stays over the same point above the equator as the Earth rotates on its axis. The structure is utilized as a transportation and utility system for moving payloads, power, and gases between the surface of the Earth and space. It makes the physical connection from Earth to space in the same way a bridge connects two cities across a body of' water. The space elevator may be an important concept for the future development of space in the latter part of the 21th century. It has the potential to provide mass-transportation to space in the same way highways, railroads, power lines, and pipelines provide mass-transportation across the Earth's surface. The low energy requirements for moving payloads up and down the elevator make it one of only a few concepts that has the potential of lowering the cost to orbit to less than $10 per kilogram. This paper will summarize the findings from a 1999 NASA workshop on Space Elevators held at the NASA Marshall Space Flight Center (MSFC). The workshop was sponsored by the Advanced Projects Office in the Flight Projects Directorate at MSFC, and was organized in cooperation with the Advanced Space Transportation Program at MSFC and the Advanced Concepts Office in the Office of Space Flight at NASA Headquarters. New concepts will be examined for space elevator construction and a number of issues will be discussed that has helped to bring the space elevator concept out of the realm of science fiction and into the realm of possibility. In conclusion, it appears that the space elevator concept may well he possible in the latter part of the 21st century if proper planning and technology development is emphasized to resolve key issues in the development of this advanced space infrastructure concept.

Advanced Mirror Technology Development for Very Large Space Telescopes

Science.gov (United States)

Stahl, H. P.

2014-01-01

Advanced Mirror Technology Development (AMTD) is a NASA Strategic Astrophysics Technology project to mature to TRL-6 the critical technologies needed to produce 4-m or larger flight-qualified UVOIR mirrors by 2018 so that a viable mission can be considered by the 2020 Decadal Review. The developed mirror technology must enable missions capable of both general astrophysics & ultra-high contrast observations of exoplanets. Just as JWST’s architecture was driven by launch vehicle, a future UVOIR mission’s architectures (monolithic, segmented or interferometric) will depend on capacities of future launch vehicles (and budget). Since we cannot predict the future, we must prepare for all potential futures. Therefore, to provide the science community with options, we are pursuing multiple technology paths. AMTD uses a science-driven systems engineering approach. We derived engineering specifications for potential future monolithic or segmented space telescopes based on science needs and implement constraints. And we are maturing six inter-linked critical technologies to enable potential future large aperture UVOIR space telescope: 1) Large-Aperture, Low Areal Density, High Stiffness Mirrors, 2) Support Systems, 3) Mid/High Spatial Frequency Figure Error, 4) Segment Edges, 5) Segment-to-Segment Gap Phasing, and 6) Integrated Model Validation Science Advisory Team and a Systems Engineering Team. We are maturing all six technologies simultaneously because all are required to make a primary mirror assembly (PMA); and, it is the PMA’s on-orbit performance which determines science return. PMA stiffness depends on substrate and support stiffness. Ability to cost-effectively eliminate mid/high spatial figure errors and polishing edges depends on substrate stiffness. On-orbit thermal and mechanical performance depends on substrate stiffness, the coefficient of thermal expansion (CTE) and thermal mass. And, segment-to-segment phasing depends on substrate & structure stiffness

A Bi-Modal Routing Problem with Cyclical and One-Way Trips: Formulation and Heuristic Solution

Directory of Open Access Journals (Sweden)

Grinde Roger B.

2017-12-01

Full Text Available A bi-modal routing problem is solved using a heuristic approach. Motivated by a recreational hiking application, the problem is similar to routing problems in business with two transport modes. The problem decomposes into a set covering problem (SCP and an asymmetric traveling salesperson problem (ATSP, corresponding to a hiking time objective and a driving distance objective. The solution algorithm considers hiking time first, but finds all alternate optimal solutions, as inputs to the driving distance problem. Results show the trade-offs between the two objectives.

Space Station galley design

Science.gov (United States)

Trabanino, Rudy; Murphy, George L.; Yakut, M. M.

1986-01-01

An Advanced Food Hardware System galley for the initial operating capability (IOC) Space Station is discussed. Space Station will employ food hardware items that have never been flown in space, such as a dishwasher, microwave oven, blender/mixer, bulk food and beverage dispensers, automated food inventory management, a trash compactor, and an advanced technology refrigerator/freezer. These new technologies and designs are described and the trades, design, development, and testing associated with each are summarized.

Go big or die out: Bifurcation and bimodality in submarine sediment flow behaviour

Science.gov (United States)

Talling, P.; Paull, C. K.; Lintern, G.; Gwiazda, R.; Cartigny, M.; Hughes Clarke, J. E.; Xu, J.; Clare, M. A.; Parsons, D. R.; Simmons, S.; Maier, K. L.; Gales, J. A.; Hage, S.; McGann, M.; Pope, E.; Rosenberger, K. J.; Stacey, C.; Barry, J.; Lundsten, E. M.; Anderson, K.; O'Reilly, T. C.; Chapplow, N.; Vendettuoli, D.

2017-12-01

Submarine flows of sediment (turbidity currents) flush globally significant volumes of sediment and organic carbon into deep-sea basins. These flows create the largest sediment accumulations on Earth, which hold valuable oil and gas reserves. These flows affect global carbon burial, how deep-sea ecosystems function, and pose a hazard to offshore infrastructure. Only river systems transport such large amounts of sediment across such long distances. However, there are remarkably few direct measurements from active submarine flows, which is a stark contrast to >1 million direct observations from rivers. Here we present unusually detailed information on frequency, power and runout distance of multiple submarine flows at two contrasting locations. The first data set comes from Monterey Canyon, offshore California, which is fed by littoral cells. The second site is a river-fed delta in Bute Inlet, British Columbia. In both cases, the timing and runout distance of submarine flows was documented using instruments on multiple moorings placed along the 50-km long flow pathway. A striking observation is that flow behaviour and runout is strongly bimodal in both locations. Flows tend to either dissipate rapidly, or runout through the entire mooring arrays. We thus test whether i) the character of short or long runout flows can be distinguished at the first mooring and ii) whether long and short runout flows have different triggers. It has been proposed that submarine flows have two modes of behaviour; either eroding and accelerating, or depositing and dissipating. These field data support such a view of bifurcation and bimodality in flow behaviour. However, some short runout flows resemble their longer runout cousins at the first mooring, and there is no clear relationship between flow trigger and runout. Thus, some flows reach a point where their character is no longer dependent on their initial trigger or initial structure, but on factors acting along the flow pathway.

Bimodality and the formation of Saturn's ring particles

International Nuclear Information System (INIS)

Gehrels, T.

1980-01-01

The F ring appears to have an outer and an inner rim, with only the latter observed by the imaging photopolarimeter (IPP) on the Pioneer Saturn spacecraft. The inside of the G ring, near 2.49 R/sub S/, may also be seen in the optical data. 1979S1 is red as well as dark. The light scattered through the B ring is noticeably red. The A ring has a dense outer rim. The Cassini Division and the French Division (Dollfus Division) have a dark gap near their centers. The C ring becomes weaker toward the center such that outer, middle, and inner C rings can be recognized. The Pioneer and earth-based observations are explained with a model for the B and A rings to some extent of a bimodal size distributions of particles; the larger ones may be original accretions, while small debris diffuses inward through the Cassini Division and the C ring. During the formation of the ring system, differential gravitation allowed only silicaceous grains of higher density (rho> or approx. =3 g cm -3 ) to coagulate. These serve as interstitial cores for snowy carbonaceous grains, between the times of accretion from interplanetary cometary grains and liberation by collision followed by diffusion inward to Saturn and final evaporation

Bimodal activated carbons derived from resorcinol-formaldehyde cryogels

Science.gov (United States)

Szczurek, Andrzej; Amaral-Labat, Gisele; Fierro, Vanessa; Pizzi, Antonio; Celzard, Alain

2011-01-01

Resorcinol-formaldehyde cryogels prepared at different dilution ratios have been activated with phosphoric acid at 450 °C and compared with their carbonaceous counterparts obtained by pyrolysis at 900 °C. Whereas the latter were, as expected, highly mesoporous carbons, the former cryogels had very different pore textures. Highly diluted cryogels allowed preparation of microporous materials with high surface areas, but activation of initially dense cryogels led to almost non-porous carbons, with much lower surface areas than those obtained by pyrolysis. The optimal acid concentration for activation, corresponding to stoichiometry between molecules of acid and hydroxyl groups, was 2 M l−1, and the acid–cryogel contact time also had an optimal value. Such optimization allowed us to achieve surface areas and micropore volumes among the highest ever obtained by activation with H3PO4, close to 2200 m2 g−1 and 0.7 cm3 g−1, respectively. Activation of diluted cryogels with a lower acid concentration of 1.2 M l−1 led to authentic bimodal activated carbons, having a surface area as high as 1780 m2 g−1 and 0.6 cm3 g−1 of microporous volume easily accessible through a widely developed macroporosity. PMID:27877405

Bimodal activated carbons derived from resorcinol-formaldehyde cryogels

Energy Technology Data Exchange (ETDEWEB)

Szczurek, Andrzej; Amaral-Labat, Gisele; Fierro, Vanessa; Celzard, Alain [Institut Jean Lamour-UMR CNRS 7198, CNRS-Nancy-Universite-UPV-Metz, Departement Chimie et Physique des Solides et des Surfaces. ENSTIB, 27 rue Philippe Seguin, BP 1041, 88051 Epinal cedex 9 (France); Pizzi, Antonio, E-mail: Alain.Celzard@enstib.uhp-nancy.fr [ENSTIB-LERMAB, Nancy-Universite, 27 rue Philippe Seguin, BP1041, 88051 Epinal cedex 9 (France)

2011-06-15

Resorcinol-formaldehyde cryogels prepared at different dilution ratios have been activated with phosphoric acid at 450 deg. C and compared with their carbonaceous counterparts obtained by pyrolysis at 900 deg. C. Whereas the latter were, as expected, highly mesoporous carbons, the former cryogels had very different pore textures. Highly diluted cryogels allowed preparation of microporous materials with high surface areas, but activation of initially dense cryogels led to almost non-porous carbons, with much lower surface areas than those obtained by pyrolysis. The optimal acid concentration for activation, corresponding to stoichiometry between molecules of acid and hydroxyl groups, was 2 M l{sup -1}, and the acid-cryogel contact time also had an optimal value. Such optimization allowed us to achieve surface areas and micropore volumes among the highest ever obtained by activation with H{sub 3}PO{sub 4}, close to 2200 m{sup 2} g{sup -1} and 0.7 cm{sup 3} g{sup -1}, respectively. Activation of diluted cryogels with a lower acid concentration of 1.2 M l{sup -1} led to authentic bimodal activated carbons, having a surface area as high as 1780 m{sup 2} g{sup -1} and 0.6 cm{sup 3} g{sup -1} of microporous volume easily accessible through a widely developed macroporosity.

Effect of carbon content on formation of bimodal microstructure and mechanical properties of low-carbon steels subjected to heavy-reduction single-pass hot/warm deformation

Energy Technology Data Exchange (ETDEWEB)

Park, Hyung-Won, E-mail: wonipark@iis.u-tokyo.ac.jp [Graduate School of Engineering, The University of Tokyo, Komaba 4-6-1, Meguro-ku 153-8505, Tokyo (Japan); Yanagimoto, Jun [Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, Meguro-ku 153-8505, Tokyo (Japan)

2014-06-01

A compression test simulating heavy-reduction single-pass rolling was conducted to investigate the microstructural evolution based on the formation of a bimodal structure and the mechanical properties of 0.01% and 0.1% carbon steels and niobium steel. When thermomechanical processing was conducted near and above the critical transformation temperature (A{sub c3}), microstructures of all steels were significantly refined and consisted of equiaxed grains without elongated grains. Nevertheless, these microstructures showed weak or no formation of the bimodal structure or coarse grains with decreasing carbon content, while they showed bimodal structure formation when 0.2% carbon steel was used in our previous research. The average grain size of Nb steel was about 2 μm and its microstructure was uniformly refined. These may be attributed to a decrease in the number of nucleation sites with decreasing carbon content in low-carbon steels and the occurrence of nucleation at grain boundaries as well as in grain interiors in Nb steel during processing. Mechanical properties of all steels deformed above the critical transformation temperature exhibited high performance characteristics with superior strength and marked elongation. Their fractographs indicated ductile fracture, which was revealed by SEM observation after a tensile test.

Advanced Biotelemetry Systems for Space Life Sciences: PH Telemetry

Science.gov (United States)

Hines, John W.; Somps, Chris; Ricks, Robert; Kim, Lynn; Connolly, John P. (Technical Monitor)

1995-01-01

The SENSORS 2000! (S2K!) program at NASA's Ames Research Center is currently developing a biotelemetry system for monitoring pH and temperature in unrestrained subjects. This activity is part of a broader scope effort to provide an Advanced Biotelemetry System (ABTS) for use in future space life sciences research. Many anticipated research endeavors will require biomedical and biochemical sensors and related instrumentation to make continuous inflight measurements in a variable-gravity environment. Since crew time is limited, automated data acquisition, data processing, data storage, and subject health monitoring are required. An automated biochemical and physiological data acquisition system based on non invasive or implantable biotelemetry technology will meet these requirements. The ABTS will ultimately acquire a variety of physiological measurands including temperature, biopotentials (e.g. ECG, EEG, EMG, EOG), blood pressure, flow and dimensions, as well as chemical and biological parameters including pH. Development activities are planned in evolutionary, leveraged steps. Near-term activities include 1) development of a dual channel pH/temperature telemetry system, and 2) development of a low bandwidth, 4-channel telemetry system, that measures temperature, heart rate, pressure, and pH. This abstract describes the pH/temperature telemeter.

Elimination of Bimodal Size in InAs/GaAs Quantum Dots for Preparation of 1.3-μm Quantum Dot Lasers.

Science.gov (United States)

Su, Xiang-Bin; Ding, Ying; Ma, Ben; Zhang, Ke-Lu; Chen, Ze-Sheng; Li, Jing-Lun; Cui, Xiao-Ran; Xu, Ying-Qiang; Ni, Hai-Qiao; Niu, Zhi-Chuan

2018-02-21

The device characteristics of semiconductor quantum dot lasers have been improved with progress in active layer structures. Self-assembly formed InAs quantum dots grown on GaAs had been intensively promoted in order to achieve quantum dot lasers with superior device performances. In the process of growing high-density InAs/GaAs quantum dots, bimodal size occurs due to large mismatch and other factors. The bimodal size in the InAs/GaAs quantum dot system is eliminated by the method of high-temperature annealing and optimized the in situ annealing temperature. The annealing temperature is taken as the key optimization parameters, and the optimal annealing temperature of 680 °C was obtained. In this process, quantum dot growth temperature, InAs deposition, and arsenic (As) pressure are optimized to improve quantum dot quality and emission wavelength. A 1.3-μm high-performance F-P quantum dot laser with a threshold current density of 110 A/cm 2 was demonstrated.

An art report to analyze research status for the establishment of the space food development and future food system using the advanced food technology

International Nuclear Information System (INIS)

Lee, Ju Woon; Byun, Myung Woo; Kim, Jae Hun

2006-12-01

The quality of food for the astronaut accomplishing the mission in the space is one of the most important matters, and it is time to study and develop Korean space food for the Korean astronaut in the space. Therefore, in the beginning of the space exploration era, it is necessary to establish a national long-term plan and study and develop Korean space food in order to provide food with better quality for the astronaut accomplishing the space mission. Using current food processing, preservation, and packaging technology, it is necessary to develop the Korean space food, provide Korean astronaut studying at the international space station, and study the future space food systems used for the long-term space voyage and planet habitat base in the era of space exploration. Space food is analyzed through nutritional analysis, sensory evaluation, storage studies, packaging evaluations, and many other methods before its final shipment on the space shuttle. Each technology developed for the advanced food system must provide the required attribute to the food system, including safety, nutrition, and acceptability. It is anticipated that the duration of the exploration class missions can be at least 2, 3 years, and one of the biggest challenges for these missions will be to provide acceptable food with a shelf-life of 3-5 years. The development of space food process/preservation technology and its ripple effect will make a contribution to the improvement of nation's international phase, and the developed space food will potentially be used for combat ration and emergency/special food like the U. S. A. In the 21th century of space exploration era, the development of the advanced food system and life support system in the Mars space base as well as the space shuttle will strengthen the capability to precede the future space exploration era

An art report to analyze research status for the establishment of the space food development and future food system using the advanced food technology

Energy Technology Data Exchange (ETDEWEB)

Lee, Ju Woon; Byun, Myung Woo; Kim, Jae Hun [KAERI, Daejeon (Korea, Republic of)

2006-12-15

The quality of food for the astronaut accomplishing the mission in the space is one of the most important matters, and it is time to study and develop Korean space food for the Korean astronaut in the space. Therefore, in the beginning of the space exploration era, it is necessary to establish a national long-term plan and study and develop Korean space food in order to provide food with better quality for the astronaut accomplishing the space mission. Using current food processing, preservation, and packaging technology, it is necessary to develop the Korean space food, provide Korean astronaut studying at the international space station, and study the future space food systems used for the long-term space voyage and planet habitat base in the era of space exploration. Space food is analyzed through nutritional analysis, sensory evaluation, storage studies, packaging evaluations, and many other methods before its final shipment on the space shuttle. Each technology developed for the advanced food system must provide the required attribute to the food system, including safety, nutrition, and acceptability. It is anticipated that the duration of the exploration class missions can be at least 2, 3 years, and one of the biggest challenges for these missions will be to provide acceptable food with a shelf-life of 3-5 years. The development of space food process/preservation technology and its ripple effect will make a contribution to the improvement of nation's international phase, and the developed space food will potentially be used for combat ration and emergency/special food like the U. S. A. In the 21th century of space exploration era, the development of the advanced food system and life support system in the Mars space base as well as the space shuttle will strengthen the capability to precede the future space exploration era

Advanced Chemical Propulsion Study

Science.gov (United States)

Woodcock, Gordon; Byers, Dave; Alexander, Leslie A.; Krebsbach, Al

2004-01-01

A study was performed of advanced chemical propulsion technology application to space science (Code S) missions. The purpose was to begin the process of selecting chemical propulsion technology advancement activities that would provide greatest benefits to Code S missions. Several missions were selected from Code S planning data, and a range of advanced chemical propulsion options was analyzed to assess capabilities and benefits re these missions. Selected beneficial applications were found for higher-performing bipropellants, gelled propellants, and cryogenic propellants. Technology advancement recommendations included cryocoolers and small turbopump engines for cryogenic propellants; space storable propellants such as LOX-hydrazine; and advanced monopropellants. It was noted that fluorine-bearing oxidizers offer performance gains over more benign oxidizers. Potential benefits were observed for gelled propellants that could be allowed to freeze, then thawed for use.

New insights into the origin of the bimodal volcanism in the middle Okinawa Trough: not a basalt-rhyolite differentiation process

Science.gov (United States)

Zhang, Yuxiang; Zeng, Zhigang; Chen, Shuai; Wang, Xiaoyuan; Yin, Xuebo

2018-06-01

In the middle Okinawa Trough (MOT), rhyolites have been typically considered as products of crystallization differentiation of basaltic magma as a feature of bimodal volcanism. However, the evidence is insufficient. This paper compared chemical trends of volcanic rocks from the MOT with fractional crystallization simulation models and experimental results and utilized trace element modeling combined with Rayleigh fractionation calculations to re-examine fractional crystallization processes in generating rhyolites. Both qualitative and quantitative studies indicate that andesites, rather than rhyolites, originate by fractional crystallization from basalts in the MOT. Furthermore, we established two batch-melting models for the MOT rhyolites and proposed that type 1 rhyolites are produced by remelting of andesites with amphiboles in the residue, while type 2 rhyolites are derived from remelting of andesites without residual amphiboles. It is difficult to produce melts with a SiO2 content ranging from 62% to 68% either by magmatic differentiation from basalts or by remelting of andesites, and this difficulty might help account for the compositional gap (Daly gap) for bimodal volcanism in the Okinawa Trough.

Distress detection, location, and communications using advanced space technology. [satellite-borne synthetic aperture radar

Science.gov (United States)

Sivertson, W. E., Jr.

1977-01-01

This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

Advanced Solar Cell and Array Technology for NASA Deep Space Missions

Science.gov (United States)

Piszczor, Michael; Benson, Scott; Scheiman, David; Finacannon, Homer; Oleson, Steve; Landis, Geoffrey

2008-01-01

A recent study by the NASA Glenn Research Center assessed the feasibility of using photovoltaics (PV) to power spacecraft for outer planetary, deep space missions. While the majority of spacecraft have relied on photovoltaics for primary power, the drastic reduction in solar intensity as the spacecraft moves farther from the sun has either limited the power available (severely curtailing scientific operations) or necessitated the use of nuclear systems. A desire by NASA and the scientific community to explore various bodies in the outer solar system and conduct "long-term" operations using using smaller, "lower-cost" spacecraft has renewed interest in exploring the feasibility of using photovoltaics for to Jupiter, Saturn and beyond. With recent advances in solar cell performance and continuing development in lightweight, high power solar array technology, the study determined that photovoltaics is indeed a viable option for many of these missions.

Thermal induced carrier's transfer in bimodal size distribution InAs/GaAs quantum dots

Science.gov (United States)

Ilahi, B.; Alshehri, K.; Madhar, N. A.; Sfaxi, L.; Maaref, H.

2018-06-01

This work reports on the investigation of the thermal induced carriers' transfer mechanism in vertically stacked bimodal size distribution InAs/GaAs quantum dots (QD). A model treating the QD as a localized states ensemble (LSE) has been employed to fit the atypical temperature dependence of the photoluminescence (PL) emission energies and linewidth. The results suggest that thermally activated carriers transfer within the large size QD family occurs through the neighboring smaller size QD as an intermediate channel before direct carriers redistribution. The obtained activation energy suggests also the possible contribution of the wetting layer (WL) continuum states as a second mediator channel for carriers transfer.

International Space Station (ISS) Advanced Recycle Filter Tank Assembly (ARFTA)

Science.gov (United States)

Nasrullah, Mohammed K.

2013-01-01

The International Space Station (ISS) Recycle Filter Tank Assembly (RFTA) provides the following three primary functions for the Urine Processor Assembly (UPA): volume for concentrating/filtering pretreated urine, filtration of product distillate, and filtration of the Pressure Control and Pump Assembly (PCPA) effluent. The RFTAs, under nominal operations, are to be replaced every 30 days. This poses a significant logistical resupply problem, as well as cost in upmass and new tanks purchase. In addition, it requires significant amount of crew time. To address and resolve these challenges, NASA required Boeing to develop a design which eliminated the logistics and upmass issues and minimize recurring costs. Boeing developed the Advanced Recycle Filter Tank Assembly (ARFTA) that allowed the tanks to be emptied on-orbit into disposable tanks that eliminated the need for bringing the fully loaded tanks to earth for refurbishment and relaunch, thereby eliminating several hundred pounds of upmass and its associated costs. The ARFTA will replace the RFTA by providing the same functionality, but with reduced resupply requirements

Advanced cryocooler electronics for space

Energy Technology Data Exchange (ETDEWEB)

Harvey, D.; Danial, A.; Godden, J.; Jackson, M.; McCuskey, J.; Valenzuela, P. [Northrop Grumman Space Technology, Redondo Beach, CA (United States); Davis, T. [Air Force Research Lab., Albuquerque, NM (United States)

2004-08-01

Space pulse-tube cryocoolers require electronics to control the cooling temperature and self-induced vibration. Other functions include engineering diagnostics, telemetry and safety protection of the unit against extreme environments and operational anomalies. The electronics must survive the harsh conditions of launch and orbit, and in some cases severe radiation environments for periods exceeding 10 years. A number of our current generation high reliability radiation hardened electronics units have been launched and others are in various stages of assembly or integration on a number of space flight programs. This paper describes the design features and performance of our next generation flight electronics designed for the STSS payloads. The electronics provides temperature control with better than +/-50 mK short-term stability. Self-induced vibration is controlled to low levels on all harmonics up to the 16th. A unique active power filter limits peak-to-peak reflected ripple current on the primary power bus to less than 3% of the average DC current. The 3 kg unit is capable of delivering 180 W continuous to NGST's high-efficiency cryocooler (HEC). (author)

Hypoxia tolerance and partitioning of bimodal respiration in the striped catfish (Pangasianodon hypophthalmus)

DEFF Research Database (Denmark)

Lefevre, Sjannie; Huong, Do Thi Thanh; Wang, Tobias

2011-01-01

Air-breathing fish are common in the tropics, and their importance in Asian aquaculture is increasing, but the respiratory physiology of some of the key species such as the striped catfish, Pangasianodon hypophthalmus Sauvage 1878 is unstudied. P. hypophthalmus is an interesting species...... to air-breathe. The possibility of reducing air-breathing frequency may be energetically beneficial for the fish, leaving more of the aerobic scope for growth and other activities, due to the proposed energetic costs of surfacing behavior....... as it appears to possess both well-developed gills and a modified swim bladder that functions as an air-breathing organ indicating a high capacity for both aquatic and aerial respiration. Using newly developed bimodal intermittent-closed respirometry, the partitioning of oxygen consumption in normoxia...

THE BIMODAL STRUCTURE OF THE SOLAR CYCLE

Energy Technology Data Exchange (ETDEWEB)

Du, Z. L., E-mail: zldu@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2015-05-01

Some properties of the 11 yr solar cycle can be explained by the current solar dynamo models. However, some other features remain not well understood such as the asymmetry of the cycle, the double-peaked structure, and the “Waldmeier effect” that a stronger cycle tends to have less rise time and a shorter cycle length. We speculate that the solar cycle is governed by a bi-dynamo model forming two stochastic processes depicted by a bimodal Gaussian function with a time gap of about 2 yr, from which the above features can be reasonably explained. The first one describes the main properties of the cycle dominated by the current solar dynamo models, and the second one occurs either in the rising phase as a short weak explosive perturbation or in the declining phase as a long stochastic perturbation. The above function is the best one selected from several in terms of the Akaike information criterion. Through analyzing different distributions, one might speculate about the dominant physical process inside the convection zone. The secondary (main) process is found to be closely associated with complicated (simple) active ranges. In effect, the bi-dynamo model is a reduced form of a multi-dynamo model, which could occur from the base of the convection zone through its envelope and from low to high heliographic latitude, reflecting the active belts in the convection zone. These results are insensitive to the hemispheric asymmetry, smoothing filters, and distribution functions selected and are expected to be helpful in understanding the formation of solar and stellar cycles.

Advancing Space Sciences through Undergraduate Research Experiences at UC Berkeley's Space Sciences Laboratory - a novel approach to undergraduate internships for first generation community college students

Science.gov (United States)

Raftery, C. L.; Davis, H. B.; Peticolas, L. M.; Paglierani, R.

2015-12-01

The Space Sciences Laboratory at UC Berkeley launched an NSF-funded Research Experience for Undergraduates (REU) program in the summer of 2015. The "Advancing Space Sciences through Undergraduate Research Experiences" (ASSURE) program recruited heavily from local community colleges and universities, and provided a multi-tiered mentorship program for students in the fields of space science and engineering. The program was focussed on providing a supportive environment for 2nd and 3rd year undergraduates, many of whom were first generation and underrepresented students. This model provides three levels of mentorship support for the participating interns: 1) the primary research advisor provides academic and professional support. 2) The program coordinator, who meets with the interns multiple times per week, provides personal support and helps the interns to assimilate into the highly competitive environment of the research laboratory. 3) Returning undergraduate interns provided peer support and guidance to the new cohort of students. The impacts of this program on the first generation students and the research mentors, as well as the lessons learned will be discussed.

Selection of high temperature thermal energy storage materials for advanced solar dynamic space power systems

Science.gov (United States)

Lacy, Dovie E.; Coles-Hamilton, Carolyn; Juhasz, Albert

1987-01-01

Under the direction of NASA's Office of Aeronautics and Technology (OAST), the NASA Lewis Research Center has initiated an in-house thermal energy storage program to identify combinations of phase change thermal energy storage media for use with a Brayton and Stirling Advanced Solar Dynamic (ASD) space power system operating between 1070 and 1400 K. A study has been initiated to determine suitable combinations of thermal energy storage (TES) phase change materials (PCM) that result in the smallest and lightest weight ASD power system possible. To date the heats of fusion of several fluoride salt mixtures with melting points greater than 1025 K have been verified experimentally. The study has indicated that these salt systems produce large ASD systems because of their inherent low thermal conductivity and low density. It is desirable to have PCMs with high densities and high thermal conductivities. Therefore, alternate phase change materials based on metallic alloy systems are also being considered as possible TES candidates for future ASD space power systems.

The Model Analysis of a Complex Tuning Fork Probe and Its Application in Bimodal Atomic Force Microscopy

Directory of Open Access Journals (Sweden)

Zhichao Wu

2017-01-01

Full Text Available A new electromechanical coupling model was built to quantitatively analyze the tuning fork probes, especially the complex ones. A special feature of a novel, soft tuning fork probe, that the second eigenfrequency of the probe was insensitive to the effective force gradient, was found and used in a homemade bimodal atomic force microscopy to measure power dissipation quantitatively. By transforming the mechanical parameters to the electrical parameters, a monotonous and concise method without using phase to calculate the power dissipation was proposed.

Deep Space Telecommunications

Science.gov (United States)

Kuiper, T. B. H.; Resch, G. M.

2000-01-01

The increasing load on NASA's deep Space Network, the new capabilities for deep space missions inherent in a next-generation radio telescope, and the potential of new telescope technology for reducing construction and operation costs suggest a natural marriage between radio astronomy and deep space telecommunications in developing advanced radio telescope concepts.

Advanced Fire Detector for Space Applications, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — New sensor technology is required to face the challenging tasks associated with future space exploration involving missions to the Moon and Mars. The safety and...

In-space research, technology and engineering experiments and Space Station

Science.gov (United States)

Tyson, Richard; Gartrell, Charles F.

1988-01-01

The NASA Space Station will serve as a technology research laboratory, a payload-servicing facility, and a large structure fabrication and assembly facility. Space structures research will encompass advanced structural concepts and their dynamics, advanced control concepts, sensors, and actuators. Experiments dealing with fluid management will gather data on such fundamentals as multiphase flow phenomena. As requirements for power systems and thermal management grow, experiments quantifying the performance of energy systems and thermal management concepts will be undertaken, together with expanded efforts in the fields of information systems, automation, and robotics.

Logistics Reduction: Advanced Clothing System (ACS)

Data.gov (United States)

National Aeronautics and Space Administration — The goal of the Advanced Exploration System (AES) Logistics Reduction (LR) project's Advanced Clothing System (ACS) is to use advanced commercial off-the-shelf...

Plastic bimodal xylogenesis in conifers from continental Mediterranean climates.

Science.gov (United States)

Camarero, Jesús Julio; Olano, José Miguel; Parras, Alfonso

2010-01-01

*Seasonal radial-increment and xylogenesis data can help to elucidate how climate modulates wood formation in conifers. Few xylogenesis studies have assessed how plastic xylogenesis is in sympatric conifer species from continental Mediterranean areas, where low winter temperatures and summer drought constrain growth. *Here, we analysed intra-annual patterns of secondary growth in sympatric conifer species (Juniperus thurifera, Pinus halepensis and Pinus sylvestris). Two field sites (xeric and mesic) were evaluated using dendrometers, microcores and climatic data. *A bimodal pattern of xylogenesis characterized by spring and autumn precipitation and subsequent cambial reactivation was detected in J. thurifera at both study sites and in P. halepensis at the xeric site, but was absent in P. sylvestris where growth was largely controlled by day length. In the xeric site J. thurifera exhibited an increased response to water availability in autumn relative to P. halepensis and summer cambial suppression was more marked in J. thurifera than in P. halepensis. *Juniperus thurifera exhibited increased plasticity in its xylogenesis pattern compared with sympatric pines, enabling this species to occupy sites with more variable climatic conditions. The plastic xylogenesis patterns of junipers in drought-stressed areas may also provide them with a competitive advantage against co-occurring pines.

Further Evidence for Geochemical Diversity, and Possible Bimodality, Among Cumulate Eucrites

Science.gov (United States)

Warren, P. H.; Kallemeyn, G. W.

1992-07-01

We have used INAA, RNAA, and fused-bead analysis to determine the bulk compositions of numerous Antarctic eucrites (and also the LEW88516 SNC meteorite). Only a few of the most unusual eucrites can be discussed in the limited space here. Takeda et al. (1988) noted that Y791195 is a slowly cooled eucrite, with an equant, medium-grained texture, and pyroxene exsolution lamellae up to 10 micrometers across. In Y791195,81-3, we find lamellae up to 14 micrometers across. In this respect, Y791195 resembles RKPA80224, in which exsolution lamellae up to 12 micrometers across. We have previously discussed the evidence that RKPA80224 is a mildly accumulative rock that formed from an unusually low-mg parent melt. Our second analysis of RKPA80224 only partly confirms the unusually low incompatible trace element (ITE) content, but the Ce anomaly is consistently small (Ce/La = 0.90-1.02 x CI), and based on a weighted mean composition the implied parent melt is still unlike any noncumulate eucrite (see Fig. 1, which shows results from mass balance calculations modeling the sample as a mixture of cumulus px and plag, plus trapped melt). A parent melt similar to an extreme low-mg, variant of the "Nuevo Laredo Trend" would plausibly account for RKPA80224. The spectrum of possible parents for Y791195 is similar, even though its "true" Sm content is slightly obscured by weathering (Ce/La = 1.4 x CI). The [Sm] used in the figure is scaled to the highest CI-normalized REE concentration. Data of Mittlefehldt and Lindstrom (1991) indicate that except for exterior samples "showing extreme rustiness," Sm even in weathered eucrites is generally not altered beyond a few tens of pct. relative (sample size seems to account for more of the variation in [Sm] among interior, non-rusty samples). Even assuming a Sm content twice that assumed in the figure, the parent melt still must be well to the low-MgO/FeO, low-Sm side of all known eucrites. The LEW87002 eucrite is brecciated, but probably

System modeling and reactor design studies of the Advanced Thermionic Initiative space nuclear reactor

International Nuclear Information System (INIS)

Lee, H.H.; Abdul-Hamid, S.; Klein, A.C.

1996-01-01

In-core thermionic space reactor design concepts that operate at a nominal power output range of 20 to 50 kW(electric) are described. Details of the neutronic, thermionic, thermal hydraulics, and shielding performance are presented. Because of the strong absorption of thermal neutrons by natural tungsten and the large amount of natural tungsten within the reactor core, two designs are considered. An overall system design code has been developed at Oregon State University to model advanced in-core thermionic energy conversion-based nuclear reactor systems for space applications. The results show that the driverless single-cell Advanced Thermionic Initiative (ATI) configuration, which does not have driver fuel rods, proved to be more efficient than the driven core, which has driver rods. The results also show that the inclusion of the true axial and radial power distribution decrease the overall conversion efficiency. The flattening of the radial power distribution by three different methods would lead to a higher efficiency. The results show that only one TFE works at the optimum emitter temperature; all other TFEs are off the optimum performance and result in a 40% decrease of the efficiency of the overall system. The true axial profile is significantly different as there is a considerable amount of neutron leakage out of the top and bottom of the reactor. The analysis reveals that the axial power profile actually has a chopped cosine shape. For this axial profile, the reactor core overall efficiency for the driverless ATI reactor version is found to be 5.84% with a total electrical power of 21.92 kW(electric). By considering the true axial power profile instead of the uniform power profile, each TFE loses ∼80 W(electric)

A Crewed Mission to Apophis Using a Hybrid Bimodal Nuclear Thermal Electric Propulsion (BNTEP) System

Science.gov (United States)

Mccurdy, David R.; Borowski, Stanley K.; Burke, Laura M.; Packard, Thomas W.

2014-01-01

A BNTEP system is a dual propellant, hybrid propulsion concept that utilizes Bimodal Nuclear Thermal Rocket (BNTR) propulsion during high thrust operations, providing 10's of kilo-Newtons of thrust per engine at a high specific impulse (Isp) of 900 s, and an Electric Propulsion (EP) system during low thrust operations at even higher Isp of around 3000 s. Electrical power for the EP system is provided by the BNTR engines in combination with a Brayton Power Conversion (BPC) closed loop system, which can provide electrical power on the order of 100's of kWe. High thrust BNTR operation uses liquid hydrogen (LH2) as reactor coolant propellant expelled out a nozzle, while low thrust EP uses high pressure xenon expelled by an electric grid. By utilizing an optimized combination of low and high thrust propulsion, significant mass savings over a conventional NTR vehicle can be realized. Low thrust mission events, such as midcourse corrections (MCC), tank settling burns, some reaction control system (RCS) burns, and even a small portion at the end of the departure burn can be performed with EP. Crewed and robotic deep space missions to a near Earth asteroid (NEA) are best suited for this hybrid propulsion approach. For these mission scenarios, the Earth return V is typically small enough that EP alone is sufficient. A crewed mission to the NEA Apophis in the year 2028 with an expendable BNTEP transfer vehicle is presented. Assembly operations, launch element masses, and other key characteristics of the vehicle are described. A comparison with a conventional NTR vehicle performing the same mission is also provided. Finally, reusability of the BNTEP transfer vehicle is explored.

New advanced TLD system for space dosimetry

International Nuclear Information System (INIS)

Feher, I.; Szabo, B.; Vagvoelgyi, J.; Deme, S.; Szabo, P.P.; Csoeke, A.

1983-10-01

A new version of the TLD reader type PILLE has been developed for space applications. The earlier compact and portable device could also be used for measurements during space flights but its range was limited. A new bulb detector with easier handling has also been developed with an upper limit of linear dose response of 10 Gy. The range of this new and more versatile reader, NA206S, (1μGy-10 Gy) is 3 orders of magnitude higher than that of the earlier system; it also has increased sensitivity and decreased mass. It can be used not only in space applications but also for environmental monitoring or even in accident dosimetry. The measured dose value is displayed on a four-digit display with automatic range switch. Another new version, the NA206E, has been developed for environmental dosimetry; it can be operated from a battery or from the mains. (author)

New advanced netted ground based and topside radio diagnostics for Space Weather Program

Science.gov (United States)

Rothkaehl, Hanna; Krankowski, Andrzej; Morawski, Marek; Atamaniuk, Barbara; Zakharenkova, Irina; Cherniak, Iurii

2014-05-01

data retrieved from FORMOSAT-3/COSMIC radio occultation measurements. The main purpose of this presentation is to describe new advanced diagnostic techniques of the near-Earth space plasma and point out the scientific challenges of the radio frequency analyser located on board of low orbiting satellites and LOFAR facilities. This research is partly supported by grant O N517 418440

Application of advanced technology to space automation

Science.gov (United States)

Schappell, R. T.; Polhemus, J. T.; Lowrie, J. W.; Hughes, C. A.; Stephens, J. R.; Chang, C. Y.

1979-01-01

Automated operations in space provide the key to optimized mission design and data acquisition at minimum cost for the future. The results of this study strongly accentuate this statement and should provide further incentive for immediate development of specific automtion technology as defined herein. Essential automation technology requirements were identified for future programs. The study was undertaken to address the future role of automation in the space program, the potential benefits to be derived, and the technology efforts that should be directed toward obtaining these benefits.

Advances in Planetary Protection at the Deep Space Gateway

Science.gov (United States)

Spry, J. A.; Siegel, B.; Race, M.; Rummel, J. D.; Pugel, D. E.; Groen, F. J.; Kminek, G.; Conley, C. A.; Carosso, N. J.

2018-02-01

Planetary protection knowledge gaps that can be addressed by science performed at the Deep Space Gateway in the areas of human health and performance, space biology, and planetary sciences that enable future exploration in deep space, at Mars, and other targets.

ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED PARTICLES FOR DIFFERENT DOSE METRICS: COMPARISON OF NUMBER, SURFACE AREA AND MASS DOSE OF TYPICAL AMBIENT BI-MODAL AEROSOLS

Science.gov (United States)

ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED PARTICLES FOR DIFFERENT DOSE METRICS: COMPARISON OF NUMBER, SURFACE AREA AND MASS DOSE OF TYPICAL AMBIENT BI-MODAL AEROSOLS.Chong S. Kim, SC. Hu*, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, ...

Far-from-Equilibrium Route to Superthermal Light in Bimodal Nanolasers

Directory of Open Access Journals (Sweden)

Mathias Marconi

2018-01-01

Full Text Available Microscale and nanoscale lasers inherently exhibit rich photon statistics due to complex light-matter interaction in a strong spontaneous emission noise background. It is well known that they may display superthermal fluctuations—photon superbunching—in specific situations due to either gain competition, leading to mode-switching instabilities, or carrier-carrier coupling in superradiant microcavities. Here we show a generic route to superbunching in bimodal nanolasers by preparing the system far from equilibrium through a parameter quench. We demonstrate, both theoretically and experimentally, that transient dynamics after a short-pump-pulse-induced quench leads to heavy-tailed superthermal statistics when projected onto the weak mode. We implement a simple experimental technique to access the probability density functions that further enables quantifying the distance from thermal equilibrium via the thermodynamic entropy. The universality of this mechanism relies on the far-from-equilibrium dynamical scenario, which can be mapped to a fast cooling process of a suspension of Brownian particles in a liquid. Our results open up new avenues to mold photon statistics in multimode optical systems and may constitute a test bed to investigate out-of-equilibrium thermodynamics using micro or nanocavity arrays.

Label-Free Biosensors Based on Bimodal Waveguide (BiMW) Interferometers.

Science.gov (United States)

Herranz, Sonia; Gavela, Adrián Fernández; Lechuga, Laura M

2017-01-01

The bimodal waveguide (BiMW) sensor is a novel common path interferometric transducer based on the evanescent field detection principle, which in combination with a bio-recognition element allows the direct detection of biomolecular interactions in a label-free scheme. Due to its inherent high sensitivity it has great potential to become a powerful analytical tool for monitoring substances of interest in areas such as environmental control, medical diagnostics and food safety, among others. The BiMW sensor is fabricated using standard silicon-based technology allowing cost-effective production, and meeting the requirements of portability and disposability necessary for implementation in a point-of-care (POC) setting.In this chapter we describe the design and fabrication of the BiMW transducer, as well as its application for bio-sensing purposes. We show as an example the biosensor capabilities two different applications: (1) the immunodetection of Irgarol 1051 biocide useful in the environmental field, and (2) the detection of human growth hormone as used in clinical diagnostics. The detection is performed in real time by monitoring changes in the intensity pattern of light exiting the BiMW transducer resulting from antigen-antibody interactions on the surface of the sensor.

Far-from-Equilibrium Route to Superthermal Light in Bimodal Nanolasers

Science.gov (United States)

Marconi, Mathias; Javaloyes, Julien; Hamel, Philippe; Raineri, Fabrice; Levenson, Ariel; Yacomotti, Alejandro M.

2018-02-01

Microscale and nanoscale lasers inherently exhibit rich photon statistics due to complex light-matter interaction in a strong spontaneous emission noise background. It is well known that they may display superthermal fluctuations—photon superbunching—in specific situations due to either gain competition, leading to mode-switching instabilities, or carrier-carrier coupling in superradiant microcavities. Here we show a generic route to superbunching in bimodal nanolasers by preparing the system far from equilibrium through a parameter quench. We demonstrate, both theoretically and experimentally, that transient dynamics after a short-pump-pulse-induced quench leads to heavy-tailed superthermal statistics when projected onto the weak mode. We implement a simple experimental technique to access the probability density functions that further enables quantifying the distance from thermal equilibrium via the thermodynamic entropy. The universality of this mechanism relies on the far-from-equilibrium dynamical scenario, which can be mapped to a fast cooling process of a suspension of Brownian particles in a liquid. Our results open up new avenues to mold photon statistics in multimode optical systems and may constitute a test bed to investigate out-of-equilibrium thermodynamics using micro or nanocavity arrays.

Advanced Manufacturing Technologies (AMT): Advanced Near Net Shape Technology

Data.gov (United States)

National Aeronautics and Space Administration — The objective of the Advanced Near Net Shape Technology (ANNST) project is to radically improve near net shape manufacturing methods from the current...

Off-design temperature effects on nuclear fuel pins for an advanced space-power-reactor concept

Science.gov (United States)

Bowles, K. J.

1974-01-01

An exploratory out-of-reactor investigation was made of the effects of short-time temperature excursions above the nominal operating temperature of 990 C on the compatibility of advanced nuclear space-power reactor fuel pin materials. This information is required for formulating a reliable reactor safety analysis and designing an emergency core cooling system. Simulated uranium mononitride (UN) fuel pins, clad with tungsten-lined T-111 (Ta-8W-2Hf) showed no compatibility problems after heating for 8 hours at 2400 C. At 2520 C and above, reactions occurred in 1 hour or less. Under these conditions free uranium formed, redistributed, and attacked the cladding.

FUSION DECISION FOR A BIMODAL BIOMETRIC VERIFICATION SYSTEM USING SUPPORT VECTOR MACHINE AND ITS VARIATIONS

Directory of Open Access Journals (Sweden)

A. Teoh

2017-12-01

Full Text Available This paw presents fusion detection technique comparisons based on support vector machine and its variations for a bimodal biometric verification system that makes use of face images and speech utterances. The system is essentially constructed by a face expert, a speech expert and a fusion decision module. Each individual expert has been optimized to operate in automatic mode and designed for security access application. Fusion decision schemes considered are linear, weighted Support Vector Machine (SVM and linear SVM with quadratic transformation. The conditions tested include the balanced and unbalanced conditions between the two experts in order to obtain the optimum fusion module from  these techniques best suited to the target application.

Generation of an N-qubit Greenberger-Horne-Zeilinger state with distant atoms in bimodal cavities

Energy Technology Data Exchange (ETDEWEB)

Zheng Anshou [School of Physics and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu Jibing, E-mail: zaszas1_1@126.com [Hubei Key Laboratory of Pollutant Analysis and Reuse Technology and Department of Physics, Hubei Normal University, Huangshi, 435002 (China)

2011-08-28

A selective photon scheme is proposed to realize an N-qubit Greenberger-Horne-Zeilinger (GHZ) state with distant atoms trapped in spatially separated bimodal cavities coupled by optical fibres. The influence of deviations of some experimental parameters on our scheme is studied exactly and we prove that a highly reliable GHZ state is achievable. Moreover, we analyse the independence of fidelity on decoherence processes, such as atomic spontaneous emission, cavity decay and fibre losses. The results show that atomic spontaneous emission and fibre losses can be ignored in some special cases. With regards to the cavity decay, it indicates that a GHZ state with high fidelity may be realized in the current experiment.

Generation of an N-qubit Greenberger-Horne-Zeilinger state with distant atoms in bimodal cavities

International Nuclear Information System (INIS)

Zheng Anshou; Liu Jibing

2011-01-01

A selective photon scheme is proposed to realize an N-qubit Greenberger-Horne-Zeilinger (GHZ) state with distant atoms trapped in spatially separated bimodal cavities coupled by optical fibres. The influence of deviations of some experimental parameters on our scheme is studied exactly and we prove that a highly reliable GHZ state is achievable. Moreover, we analyse the independence of fidelity on decoherence processes, such as atomic spontaneous emission, cavity decay and fibre losses. The results show that atomic spontaneous emission and fibre losses can be ignored in some special cases. With regards to the cavity decay, it indicates that a GHZ state with high fidelity may be realized in the current experiment.

Spaces an introduction to real analysis

CERN Document Server

Lindstrøm, Tom L

2017-01-01

Spaces is a modern introduction to real analysis at the advanced undergraduate level. It is forward-looking in the sense that it first and foremost aims to provide students with the concepts and techniques they need in order to follow more advanced courses in mathematical analysis and neighboring fields. The only prerequisites are a solid understanding of calculus and linear algebra. Two introductory chapters will help students with the transition from computation-based calculus to theory-based analysis. The main topics covered are metric spaces, spaces of continuous functions, normed spaces, differentiation in normed spaces, measure and integration theory, and Fourier series. Although some of the topics are more advanced than what is usually found in books of this level, care is taken to present the material in a way that is suitable for the intended audience: concepts are carefully introduced and motivated, and proofs are presented in full detail. Applications to differential equations and Fourier analysis ...

Space and energy. [space systems for energy generation, distribution and control

Science.gov (United States)

Bekey, I.

1976-01-01

Potential contributions of space to energy-related activities are discussed. Advanced concepts presented include worldwide energy distribution to substation-sized users using low-altitude space reflectors; powering large numbers of large aircraft worldwide using laser beams reflected from space mirror complexes; providing night illumination via sunlight-reflecting space mirrors; fine-scale power programming and monitoring in transmission networks by monitoring millions of network points from space; prevention of undetected hijacking of nuclear reactor fuels by space tracking of signals from tagging transmitters on all such materials; and disposal of nuclear power plant radioactive wastes in space.

Developing a Free-Piston Stirling Convertor for advanced radioisotope space power systems

Science.gov (United States)

Qiu, Songgang; Augenblick, John E.; White, Maurice A.; Peterson, Allen A.; Redinger, Darin L.; Petersen, Stephen L.

2002-01-01

The Department of Energy (DOE) has selected Free-Piston Stirling Convertors as a technology for future advanced radioisotope space power systems. In August 2000, DOE awarded competitive Phase I, Stirling Radioisotope Generator (SRG) power system integration contracts to three major aerospace contractors, resulting in SRG conceptual designs in February 2001. All three contractors based their designs on the Technology Demonstration Convertor (TDC) developed by Stirling Technology Company (STC) for DOE. The contract award to a single system integration contractor for Phases II and III of the SRG program is anticipated in late 2001. The first potential SRG mission is targeted for a Mars rover. This paper provides a description of the Flight Prototype (FP) Stirling convertor design as compared to the previous TDC design. The initial flight prototype units are already undergoing performance tuning at STC. The new design will be hermetically scaled and will provide a weight reduction from approximately 4.8 kg to approximately 3.9 kg. .

Advanced Topics in Space Situational Awareness

Science.gov (United States)

2007-11-07

identification, adaptive optics 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF ABSTRACT OF PAGES Sudhakar Prasad... Optical Sciences Center, University of Arizona (co-PI) " Dr. Stuart M. Jefferies, Professor, IfA, University of Hawaii (Co-PI) " Dr. Robert J. Plemmons...available at AMOS for conducting imaging and nonimaging research and data analysis; " transition advanced mathematical concepts and software resulting

Bi-Modal Micro-Cathode Arc Thruster for Cube Satellites

Science.gov (United States)

Chiu, Dereck

A new concept design, named the Bi-Modal Micro-Cathode Arc Thruster (BM-muCAT), has been introduced utilizing features from previous generations of muCATs and incorporating a multi-propellant functionality. This arc thruster is a micro-Newton level thruster based off of vacuum arc technology utilizing an enhanced magnetic field. Adjusting the magnetic field allows the thrusters performance to be varied. The goal of this thesis is to present a new generation of micro-cathode arc thrusters utilizing a bi-propellant, nickel and titanium, system. Three experimental procedures were run to test the new designs capabilities. Arc rotation experiment was used as a base experiment to ensure erosion was occurring uniformly along each electrode. Ion utilization efficiency was found, using an ion collector, to be up to 2% with the nickel material and 2.5% with the titanium material. Ion velocities were also studied using a time-of-flight method with an enhanced ion detection system. This system utilizes double electrostatic probes to measure plasma propagation. Ion velocities were measured to be 10km/s and 20km/s for nickel and titanium without a magnetic field. With an applied magnetic field of 0.2T, nickel ion velocities almost doubled to about 17km/s, while titanium ion velocities also increased to about 30km/s.

Advanced Microelectronics Technologies for Future Small Satellite Systems

Science.gov (United States)

Alkalai, Leon

1999-01-01

Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Whereas these technological advances are being fueled by the commercial (non-space) industries, more recently there has been an exciting new synergism evolving between the two otherwise disjointed markets. In other words, both the commercial and space industries are enabled by advances in low-power, highly integrated, miniaturized (low-volume), lightweight, and reliable real-time embedded systems. Recent announcements by commercial semiconductor manufacturers to introduce Silicon On Insulator (SOI) technology into their commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications. In this paper, we describe the advanced microelectronics and avionics technologies under development by NASA's Deep Space Systems Technology Program (also known as X2000). These technologies are of significant benefit to both the commercial satellite as well as the deep-space and Earth orbiting science missions. Such a synergistic technology roadmap may truly enable quick turn-around, low-cost, and highly capable small satellite systems for both Earth observation as well as deep-space missions.

Bimodal distribution of the magnetic dipole moment in nanoparticles with a monomodal distribution of the physical size

International Nuclear Information System (INIS)

Rijssel, Jos van; Kuipers, Bonny W.M.; Erné, Ben H.

2015-01-01

High-frequency applications of magnetic nanoparticles, such as therapeutic hyperthermia and magnetic particle imaging, are sensitive to nanoparticle size and dipole moment. Usually, it is assumed that magnetic nanoparticles with a log-normal distribution of the physical size also have a log-normal distribution of the magnetic dipole moment. Here, we test this assumption for different types of superparamagnetic iron oxide nanoparticles in the 5–20 nm range, by multimodal fitting of magnetization curves using the MINORIM inversion method. The particles are studied while in dilute colloidal dispersion in a liquid, thereby preventing hysteresis and diminishing the effects of magnetic anisotropy on the interpretation of the magnetization curves. For two different types of well crystallized particles, the magnetic distribution is indeed log-normal, as expected from the physical size distribution. However, two other types of particles, with twinning defects or inhomogeneous oxide phases, are found to have a bimodal magnetic distribution. Our qualitative explanation is that relatively low fields are sufficient to begin aligning the particles in the liquid on the basis of their net dipole moment, whereas higher fields are required to align the smaller domains or less magnetic phases inside the particles. - Highlights: • Multimodal fits of dilute ferrofluids reveal when the particles are multidomain. • No a priori shape of the distribution is assumed by the MINORIM inversion method. • Well crystallized particles have log-normal TEM and magnetic size distributions. • Defective particles can combine a monomodal size and a bimodal dipole moment

Advanced stellar compass deep space navigation, ground testing results

DEFF Research Database (Denmark)

Betto, Maurizio; Jørgensen, John Leif; Jørgensen, Peter Siegbjørn

2006-01-01

Deep space exploration is in the agenda of the major space agencies worldwide and at least the European Space Agency (SMART & Aurora Programs) and the American NASA (New Millennium Program) have set up programs to allow the development and the demonstration of technologies that can reduce the risks...... and the costs of the deep space missions. Navigation is the Achilles' heel of deep space. Being performed on ground, it imposes considerable constraints on the system and the operations, it is very expensive to execute, especially when the mission lasts several years and, above all, it is not failure tolerant...... to determine the orbit of a spacecraft autonomously, on-board and without any a priori knowledge of any kind. The solution is robust, elegant and fast. This paper presents the preliminary performances obtained during the ground tests. The results are very positive and encouraging....

Evaluation of prototype Advanced Life Support (ALS) pack for use by the Health Maintenance Facility (HMF) on Space Station Freedom (SSF)

Science.gov (United States)

Krupa, Debra T.; Gosbee, John; Murphy, Linda; Kizzee, Victor D.

1991-01-01

The purpose is to evaluate the prototype Advanced Life Support (ALS) Pack which was developed for the Health Maintenance Facility (HMF). This pack will enable the Crew Medical Officer (CMO) to have ready access to advanced life support supplies and equipment for time critical responses to any situation within the Space Station Freedom. The objectives are: (1) to evaluate the design of the pack; and (2) to collect comments for revision to the design of the pack. The in-flight test procedures and other aspects of the KC-135 parabolic test flight to simulate weightlessness are presented.

Advanced Electronics

Science.gov (United States)

2017-07-21

AFRL-RV-PS- AFRL-RV-PS- TR-2017-0114 TR-2017-0114 ADVANCED ELECTRONICS Ashwani Sharma 21 Jul 2017 Interim Report APPROVED FOR PUBLIC RELEASE...NUMBER Advanced Electronics 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6. AUTHOR(S) 5d. PROJECT NUMBER 4846 Ashwani Sharma 5e. TASK NUMBER...Approved for public release; distribution is unlimited. (RDMX-17-14919 dtd 20 Mar 2018) 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Space Electronics

Space station propulsion requirements study

Science.gov (United States)

Wilkinson, C. L.; Brennan, S. M.

1985-01-01

Propulsion system requirements to support Low Earth Orbit (LEO) manned space station development and evolution over a wide range of potential capabilities and for a variety of STS servicing and space station operating strategies are described. The term space station and the overall space station configuration refers, for the purpose of this report, to a group of potential LEO spacecraft that support the overall space station mission. The group consisted of the central space station at 28.5 deg or 90 deg inclinations, unmanned free-flying spacecraft that are both tethered and untethered, a short-range servicing vehicle, and a longer range servicing vehicle capable of GEO payload transfer. The time phasing for preferred propulsion technology approaches is also investigated, as well as the high-leverage, state-of-the-art advancements needed, and the qualitative and quantitative benefits of these advancements on STS/space station operations. The time frame of propulsion technologies applicable to this study is the early 1990's to approximately the year 2000.

DMAP-BODIPY alkynes: a convenient tool for labeling biomolecules for bimodal PET-optical imaging.

Science.gov (United States)

Brizet, Bertrand; Goncalves, Victor; Bernhard, Claire; Harvey, Pierre D; Denat, Franck; Goze, Christine

2014-09-26

Several new boron dipyrromethene/N,N-dimethylaminopyridine (BODIPY-DMAP) assemblies were synthesized as precursors for bimodal imaging probes (optical imaging, OI/positron emission tomography, PET). The photophysical properties of the new compounds were also studied. The first proof-of-concept was obtained with the preparation of several new BODIPY-labeled bombesins and evaluation of the affinity for bombesin receptors by using a competition binding assay. Fluorination reactions were investigated on DMAP-BODIPY precursors as well as on DMAP-BODIPY-labeled bombesins. Chemical modifications on the BODIPY core were also performed to obtain luminescent dyes emitting in the therapeutic window (650-900 nm), suitable for in vivo imaging, making these compounds promising precursors for PET/optical dual-modality imaging agents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Particle filtering with path sampling and an application to a bimodal ocean current model

International Nuclear Information System (INIS)

Weare, Jonathan

2009-01-01

This paper introduces a recursive particle filtering algorithm designed to filter high dimensional systems with complicated non-linear and non-Gaussian effects. The method incorporates a parallel marginalization (PMMC) step in conjunction with the hybrid Monte Carlo (HMC) scheme to improve samples generated by standard particle filters. Parallel marginalization is an efficient Markov chain Monte Carlo (MCMC) strategy that uses lower dimensional approximate marginal distributions of the target distribution to accelerate equilibration. As a validation the algorithm is tested on a 2516 dimensional, bimodal, stochastic model motivated by the Kuroshio current that runs along the Japanese coast. The results of this test indicate that the method is an attractive alternative for problems that require the generality of a particle filter but have been inaccessible due to the limitations of standard particle filtering strategies.

Advanced Situation Awareness Technologies, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Advanced Situation Awareness Technologies (ASAT) will facilitate exploration of the moon surface, and other planetary bodies. ASAT will create an Advanced Situation...

Space Biology Model Organism Research on the Deep Space Gateway to Pioneer Discovery and Advance Human Space Exploration

Science.gov (United States)

Sato, K. Y.; Tomko, D. L.; Levine, H. G.; Quincy, C. D.; Rayl, N. A.; Sowa, M. B.; Taylor, E. M.; Sun, S. C.; Kundrot, C. E.

2018-02-01

Model organisms are foundational for conducting physiological and systems biology research to define how life responds to the deep space environment. The organisms, areas of research, and Deep Space Gateway capabilities needed will be presented.

Concurrent Multidisciplinary Preliminary Assessment of Space Systems (COMPASS) Final Report: Advanced Long-Life Lander Investigating the Venus Environment (ALIVE)

Science.gov (United States)

Oleson, Steven R.

2018-01-01

The COncurrent Multidisciplinary Preliminary Assessment of Space Systems (COMPASS) Team partnered with the Applied Research Laboratory to perform a NASA Innovative Advanced Concepts (NIAC) Program study to evaluate chemical based power systems for keeping a Venus lander alive (power and cooling) and functional for a period of days. The mission class targeted was either a Discovery ($500M) or New Frontiers ($750M to $780M) class mission.

Preliminary test results from a free-piston Stirling engine technology demonstration program to support advanced radioisotope space power applications

International Nuclear Information System (INIS)

White, Maurice A.; Qiu Songgang; Augenblick, Jack E.

2000-01-01

Free-piston Stirling engines offer a relatively mature, proven, long-life technology that is well-suited for advanced, high-efficiency radioisotope space power systems. Contracts from DOE and NASA are being conducted by Stirling Technology Company (STC) for the purpose of demonstrating the Stirling technology in a configuration and power level that is representative of an eventual space power system. The long-term objective is to develop a power system with an efficiency exceeding 20% that can function with a high degree of reliability for up to 15 years on deep space missions. The current technology demonstration convertors (TDC's) are completing shakedown testing and have recently demonstrated performance levels that are virtually identical to projections made during the preliminary design phase. This paper describes preliminary test results for power output, efficiency, and vibration levels. These early results demonstrate the ability of the free-piston Stirling technology to exceed objectives by approximately quadrupling the efficiency of conventional radioisotope thermoelectric generators (RTG's)

Preliminary test results from a free-piston Stirling engine technology demonstration program to support advanced radioisotope space power applications

Science.gov (United States)

White, Maurice A.; Qiu, Songgang; Augenblick, Jack E.

2000-01-01

Free-piston Stirling engines offer a relatively mature, proven, long-life technology that is well-suited for advanced, high-efficiency radioisotope space power systems. Contracts from DOE and NASA are being conducted by Stirling Technology Company (STC) for the purpose of demonstrating the Stirling technology in a configuration and power level that is representative of an eventual space power system. The long-term objective is to develop a power system with an efficiency exceeding 20% that can function with a high degree of reliability for up to 15 years on deep space missions. The current technology demonstration convertors (TDC's) are completing shakedown testing and have recently demonstrated performance levels that are virtually identical to projections made during the preliminary design phase. This paper describes preliminary test results for power output, efficiency, and vibration levels. These early results demonstrate the ability of the free-piston Stirling technology to exceed objectives by approximately quadrupling the efficiency of conventional radioisotope thermoelectric generators (RTG's). .

Observing photons in space a guide to experimental space astronomy

CERN Document Server

Pauluhn, Anuschka; Culhane, J; Timothy, J; Wilhelm, Klaus; Zehnder, Alex

2013-01-01

An ideal resource for lecturers, this book provides a comprehensive review of experimental space astronomy. The number of astronomers whose knowledge and interest is concentrated on interpreting observations has grown substantially in the past decades; yet, the number of scientists who are familiar with and capable of dealing with instrumentation has dwindled.  All of the authors of this work are leading and experienced experts and practitioners who have designed, built, tested, calibrated, launched and operated advanced observing equipment for space astronomy. This book also contains concise information on the history of the field, supported by appropriate references. Moreover, scientists working in other fields will be able to get a quick overview of the salient issues of observing photons in any one of the various energy, wavelength and frequency ranges accessible in space. This book was written with the intention to make it accessible to advanced undergraduate and graduate students.

Advances in space biology and medicine. Vol. 1

Science.gov (United States)

Bonting, Sjoerd L. (Editor)

1991-01-01

Topics discussed include the effects of prolonged spaceflights on the human body; skeletal responses to spaceflight; gravity effects on reproduction, development, and aging; neurovestibular physiology in fish; and gravity perception and circumnutation in plants. Attention is also given to the development of higher plants under altered gravitational conditions; the techniques, findings, and theory concerning gravity effects on single cells; protein crystal growth in space; and facilities for animal research in space.

USSR Space Life Sciences Digest

Science.gov (United States)

Lewis, C. S. (Editor); Donnelly, K. L. (Editor)

1980-01-01

Research in exobiology, life sciences technology, space biology, and space medicine and physiology, primarily using data gathered on the Salyut 6 orbital space station, is reported. Methods for predicting, diagnosing, and preventing the effects of weightlessness are discussed. Psychological factors are discussed. The effects of space flight on plants and animals are reported. Bioinstrumentation advances are noted.

Advanced Space Power Systems (ASPS): Regenerative Fuel Cells (RFC)

Data.gov (United States)

National Aeronautics and Space Administration — The objective of the regenerative fuel cell project element is to develop power and energy storage technologies that enable new capabilities for future human space...

Dedicated Space | Poster

Science.gov (United States)

The three-story, 330,000-square-foot Advanced Technology Research Facility has nearly 40,000 square feet designated as partnership space (shown in blue) for co-location of collaborators from industry, academia, nonprofit sectors, and other government agencies. The partnership space, combined with multiple conference rooms and meeting areas, encourages both internal and

Artificial intelligence - NASA. [robotics for Space Station

Science.gov (United States)

Erickson, J. D.

1985-01-01

Artificial Intelligence (AI) represents a vital common space support element needed to enable the civil space program and commercial space program to perform their missions successfully. It is pointed out that advances in AI stimulated by the Space Station Program could benefit the U.S. in many ways. A fundamental challenge for the civil space program is to meet the needs of the customers and users of space with facilities enabling maximum productivity and having low start-up costs, and low annual operating costs. An effective way to meet this challenge may involve a man-machine system in which artificial intelligence, robotics, and advanced automation are integrated into high reliability organizations. Attention is given to the benefits, NASA strategy for AI, candidate space station systems, the Space Station as a stepping stone, and the commercialization of space.

An investigation of bimodal jet trajectory in flow through scaled models of the human vocal tract

Energy Technology Data Exchange (ETDEWEB)

Erath, Byron D.; Plesniak, Michael W. [Purdue University, School of Mechanical Engineering, Indiana (United States)

2006-05-15

Pulsatile two-dimensional flow through static divergent models of the human vocal folds is investigated. Although the motivation for this study is speech production, the results are generally applicable to a variety of engineering flows involving pulsatile flow through diffusers. Model glottal divergence angles of 10, 20, and 40 represent various geometries encountered in one phonation cycle. Frequency and amplitude of the flow oscillations are scaled with physiological Reynolds and Strouhal numbers typical of human phonation. Glottal velocity trajectories are measured along the anterior-posterior midline by using phase-averaged particle image velocimetry to acquire 1,000 realizations at ten discrete instances in the phonation cycle. The angular deflection of the glottal jet from the streamwise direction (symmetric configuration) is quantified for each realization. A bimodal flow configuration is observed for divergence angles of 10 and 20 , with the flow eventually skewing and attaching to the vocal fold walls. The deflection of the flow toward the vocal fold walls occurs when the forcing function reaches maximum velocity and zero acceleration. For a divergence angle of 40 , the flow never attaches to the vocal fold walls; however, there is increased variability in the glottal jet after the forcing function reaches maximum velocity and zero acceleration. The variation in the jet trajectory as a function of divergence angle is explained by performance maps of diffuser flow regimes. The smaller angle cases are in the unstable transitory stall regime while the 40 divergent case is in the fully developed two-dimensional stall regime. Very small geometric variations in model size and surface finish significantly affect the flow behavior. The bimodal, or flip-flopping, glottal jet behavior is expected to influence the dipole contribution to sound production. (orig.)

Equipment concept design and development plans for microgravity science and applications research on space station: Combustion tunnel, laser diagnostic system, advanced modular furnace, integrated electronics laboratory

Science.gov (United States)

Uhran, M. L.; Youngblood, W. W.; Georgekutty, T.; Fiske, M. R.; Wear, W. O.

1986-01-01

Taking advantage of the microgravity environment of space NASA has initiated the preliminary design of a permanently manned space station that will support technological advances in process science and stimulate the development of new and improved materials having applications across the commercial spectrum. Previous studies have been performed to define from the researcher's perspective, the requirements for laboratory equipment to accommodate microgravity experiments on the space station. Functional requirements for the identified experimental apparatus and support equipment were determined. From these hardware requirements, several items were selected for concept designs and subsequent formulation of development plans. This report documents the concept designs and development plans for two items of experiment apparatus - the Combustion Tunnel and the Advanced Modular Furnace, and two items of support equipment the Laser Diagnostic System and the Integrated Electronics Laboratory. For each concept design, key technology developments were identified that are required to enable or enhance the development of the respective hardware.

Advanced Technologies for Robotic Exploration Leading to Human Exploration: Results from the SpaceOps 2015 Workshop

Science.gov (United States)

Lupisella, Mark L.; Mueller, Thomas

2016-01-01

This paper will provide a summary and analysis of the SpaceOps 2015 Workshop all-day session on "Advanced Technologies for Robotic Exploration, Leading to Human Exploration", held at Fucino Space Center, Italy on June 12th, 2015. The session was primarily intended to explore how robotic missions and robotics technologies more generally can help lead to human exploration missions. The session included a wide range of presentations that were roughly grouped into (1) broader background, conceptual, and high-level operations concepts presentations such as the International Space Exploration Coordination Group Roadmap, followed by (2) more detailed narrower presentations such as rover autonomy and communications. The broader presentations helped to provide context and specific technical hooks, and helped lay a foundation for the narrower presentations on more specific challenges and technologies, as well as for the discussion that followed. The discussion that followed the presentations touched on key questions, themes, actions and potential international collaboration opportunities. Some of the themes that were touched on were (1) multi-agent systems, (2) decentralized command and control, (3) autonomy, (4) low-latency teleoperations, (5) science operations, (6) communications, (7) technology pull vs. technology push, and (8) the roles and challenges of operations in early human architecture and mission concept formulation. A number of potential action items resulted from the workshop session, including: (1) using CCSDS as a further collaboration mechanism for human mission operations, (2) making further contact with subject matter experts, (3) initiating informal collaborative efforts to allow for rapid and efficient implementation, and (4) exploring how SpaceOps can support collaboration and information exchange with human exploration efforts. This paper will summarize the session and provide an overview of the above subjects as they emerged from the SpaceOps 2015

White space communication advances, developments and engineering challenges

CERN Document Server

Johnson, David

2015-01-01

This monograph presents a collection of major developments leading toward the implementation of white space technology - an emerging wireless standard for using wireless spectrum in locations where it is unused by licensed users. Some of the key research areas in the field are covered. These include emerging standards, technical insights from early pilots and simulations, software defined radio platforms, geo-location spectrum databases and current white space spectrum usage in India and South Africa.

Space Bugz!

DEFF Research Database (Denmark)

Birke, Alexander; Schoenau-Fog, Henrik; Reng, Lars

2012-01-01

This paper presents Space Bugz! - a novel crowd game for large venues or cinemas that utilises the audience's smartphones as controllers for the game. This paper explains what crowd gaming is and describes how the approach used in Space Bugz! enables more advanced gameplay concepts and individual...... player control than current technologies allow. The gameplay of Space Bugz! is then explained along with the technical architecture of the game. After this, the iterative design process used to create the game is described together with future perspectives. The article concludes with links to a video...

Human Exploration System Test-Bed for Integration and Advancement (HESTIA) Support of Future NASA Deep-Space Missions

Science.gov (United States)

Marmolejo, Jose; Ewert, Michael

2016-01-01

The Engineering Directorate at the NASA - Johnson Space Center is outfitting a 20-Foot diameter hypobaric chamber in Building 7 to support future deep-space Environmental Control & Life Support System (ECLSS) research as part of the Human Exploration System Test-bed for Integration and Advancement (HESTIA) Project. This human-rated chamber is the only NASA facility that has the unique experience, chamber geometry, infrastructure, and support systems capable of conducting this research. The chamber was used to support Gemini, Apollo, and SkyLab Missions. More recently, it was used to conduct 30-, 60-, and 90-day human ECLSS closed-loop testing in the 1990s to support the International Space Station and life support technology development. NASA studies show that both planetary surface and deep-space transit crew habitats will be 3-4 story cylindrical structures driven by human occupancy volumetric needs and launch vehicle constraints. The HESTIA facility offers a 3-story, 20-foot diameter habitat consistent with the studies' recommendations. HESTIA operations follow stringent processes by a certified test team that including human testing. Project management, analysis, design, acquisition, fabrication, assembly and certification of facility build-ups are available to support this research. HESTIA offers close proximity to key stakeholders including astronauts, Human Research Program (who direct space human research for the agency), Mission Operations, Safety & Mission Assurance, and Engineering Directorate. The HESTIA chamber can operate at reduced pressure and elevated oxygen environments including those proposed for deep-space exploration. Data acquisition, power, fluids and other facility resources are available to support a wide range of research. Recently completed HESTIA research consisted of unmanned testing of ECLSS technologies. Eventually, the HESTIA research will include humans for extended durations at reduced pressure and elevated oxygen to demonstrate

Spatio-Temporal Variability of Summer Precipitation in Mexico under the Influence of the MJO, with Emphasis on the Bimodal Pattern

Science.gov (United States)

Perdigón, J.; Romero-Centeno, R.; Barrett, B.; Ordoñez-Perez, P.

2017-12-01

In many regions of Mexico, precipitation occurs in a very well defined annual cycle with peaks in May-June and September-October and a relative minimum in the middle of the rainy season known as the midsummer drought (MSD). The MJO is the most important mode of intraseasonal variability in the tropics, and, although some studies have shown its evident influence on summer precipitation in Mexico, its role in modulating the bimodal pattern of the summer precipitation cycle is still an open question. The spatio-temporal variability of summer precipitation in Mexico is analyzed through composite analysis according to the phases of the MJO, using the very high resolution CHIRPS precipitation data base and gridded data from the CFSR reanalysis to analyzing the MJO influence on the atmospheric circulation over Mexico and its adjacent basins. In general, during MJO phases 8-2 (4-6) rainfall is above-normal (below-normal), although, in some cases, the summer rainfall patterns during the same phase present considerable differences. The atmospheric circulation shows low (high) troposphere southwesterly (northeasterly) wind anomalies in southern Mexico under wetter conditions compared with climatological patterns, while the inverse pattern is observed under drier conditions. Composite anomalies of several variables also agreed well with those rainfall anomalies. Finally, a MJO complete cycle that reinforces (weakens) the bimodal pattern of summer rainfall in Mexico was found.

Advanced Space Power Systems (ASPS): Advanced Microelectromechanical (MEMs) Photovoltaic Systems (AMPS) Project

Data.gov (United States)

National Aeronautics and Space Administration — Develop new cell and blanket technologies and manufacturing processes that reduce overall array costs•Cells: develop new cell technology comparable to SOA with...

Advances in Rodent Research Missions on the International Space Station

Science.gov (United States)

Choi, S. Y.; Ronca, A.; Leveson-Gower, D.; Gong, C.; Stube, K.; Pletcher, D.; Wigley, C.; Beegle, J.; Globus, R. K.

2016-01-01

A research platform for rodent experiment on the ISS is a valuable tool for advancing biomedical research in space. Capabilities offered by the Rodent Research project developed at NASA Ames Research Center can support experiments of much longer duration on the ISS than previous experiments performed on the Space Shuttle. NASAs Rodent Research (RR)-1 mission was completed successfully and achieved a number of objectives, including validation of flight hardware, on-orbit operations, and science capabilities as well as support of a CASIS-sponsored experiment (Novartis) on muscle atrophy. Twenty C57BL6J adult female mice were launched on the Space-X (SpX) 4 Dragon vehicle, and thrived for up to 37 days in microgravity. Daily health checks of the mice were performed during the mission via downlinked video; all flight animals were healthy and displayed normal behavior, and higher levels of physical activity compared to ground controls. Behavioral analysis demonstrated that Flight and Ground Control mice exhibited the same range of behaviors, including eating, drinking, exploratory behavior, self- and allo-grooming, and social interactions indicative of healthy animals. The animals were euthanized on-orbit and select tissues were collected from some of the mice on orbit to assess the long-term sample storage capabilities of the ISS. In general, the data obtained from the flight mice were comparable to those from the three groups of control mice (baseline, vivarium and ground controls, which were housed in flight hardware), showing that the ISS has adequate capability to support long-duration rodent experiments. The team recovered 35 tissues from 40 RR-1 frozen carcasses, yielding 3300 aliquots of tissues to distribute to the scientific community in the U.S., including NASAs GeneLab project and scientists via Space Biology's Biospecimen Sharing Program Ames Life Science Data Archive. Tissues also were distributed to Russian research colleagues at the Institute for

Space engineering modeling and optimization with case studies

CERN Document Server

Pintér, János

2016-01-01

This book presents a selection of advanced case studies that cover a substantial range of issues and real-world challenges and applications in space engineering. Vital mathematical modeling, optimization methodologies and numerical solution aspects of each application case study are presented in detail, with discussions of a range of advanced model development and solution techniques and tools. Space engineering challenges are discussed in the following contexts: •Advanced Space Vehicle Design •Computation of Optimal Low Thrust Transfers •Indirect Optimization of Spacecraft Trajectories •Resource-Constrained Scheduling, •Packing Problems in Space •Design of Complex Interplanetary Trajectories •Satellite Constellation Image Acquisition •Re-entry Test Vehicle Configuration Selection •Collision Risk Assessment on Perturbed Orbits •Optimal Robust Design of Hybrid Rocket Engines •Nonlinear Regression Analysis in Space Engineering< •Regression-Based Sensitivity Analysis and Robust Design ...

Space-Ready Advanced Imaging System, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — In this Phase II effort Toyon will increase the state-of-the-art for video/image systems. This will include digital image compression algorithms as well as system...

Securing Data for Space Communications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA's vision of data exchange between space and ground nodes would involve the space network accessing public infrastructure such as the internet. Hence, advanced...

Colorimetric and Fluorescent Bimodal Ratiometric Probes for pH Sensing of Living Cells.

Science.gov (United States)

Liu, Yuan-Yuan; Wu, Ming; Zhu, Li-Na; Feng, Xi-Zeng; Kong, De-Ming

2015-06-01

pH measurement is widely used in many fields. Ratiometric pH sensing is an important way to improve the detection accuracy. Herein, five water-soluble cationic porphyrin derivatives were synthesized and their optical property changes with pH value were investigated. Their pH-dependent assembly/disassembly behaviors caused significant changes in both absorption and fluorescence spectra, thus making them promising bimodal ratiometric probes for both colorimetric and fluorescent pH sensing. Different substituent identity and position confer these probes with different sensitive pH-sensing ranges, and the substituent position gives a larger effect. By selecting different porphyrins, different signal intensity ratios and different fluorescence excitation wavelengths, sensitive pH sensing can be achieved in the range of 2.1-8.0. Having demonstrated the excellent reversibility, good accuracy and low cytotoxicity of the probes, they were successfully applied in pH sensing inside living cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Invited Review Article: Advanced light microscopy for biological space research

NARCIS (Netherlands)

De Vos, W.H.; Beghuin, D.; Schwarz, C.J.; Jones, D.B.; van Loon, J.J.W.A.; Bereiter-Hahn, J.; Stelzer, E.H.K.

2014-01-01

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as

Invited review article: advanced light microscopy for biological space research

NARCIS (Netherlands)

De Vos, W.H.; Beghuin, D.; Schwarz, C.J.; Jones, D.B.; van Loon, J.J.W.A.; Bereiter-Hahn, J.; Stelzer, E.H.K.

2014-01-01

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as

Advanced Welding Applications

Science.gov (United States)

Ding, Robert J.

2010-01-01

Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

Role of block copolymer adsorption versus bimodal grafting on nanoparticle self-assembly in polymer nanocomposites.

Science.gov (United States)

Zhao, Dan; Di Nicola, Matteo; Khani, Mohammad M; Jestin, Jacques; Benicewicz, Brian C; Kumar, Sanat K

2016-09-14

We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities. We postulate that this difference arises because of two factors inherent in the synthesis of the NPs: In the case of the BCP NPs the adsorption process is analogous to the chains being "grafted to" the NP surface, while the BM case corresponds to "grafting from" the surface. We have shown that the "grafted from" protocol yields patchy NPs even if the graft points are uniformly placed on each particle. This phenomenon, which is caused by chain conformation fluctuations, is exacerbated by the distribution function associated with the (small) number of grafts per particle. In contrast, in the case of BCP adsorption, each NP is more uniformly coated by a P2VP monolayer driven by the strongly favorable P2VP-silica interactions. Since each P2VP block is connected to a PS chain we conjecture that these adsorbed systems are closer to the limit of spatially uniform sparse brush coverage than the chemically grafted case. We finally show that the better NP dispersion resulting from BCP adsorption leads to larger mechanical reinforcement than those achieved with BM particles. These results emphasize that physical adsorption of BCPs is a simple, effective and practically promising strategy to direct NP dispersion in a chemically unfavorable polymer matrix.

A Technology Plan for Enabling Commercial Space Business

Science.gov (United States)

Lyles, Garry M.

1997-01-01

The National Aeronautics and Space Administration's (NASA) Advanced Space Transportation Program is a customer driven, focused technology program that supports the NASA Strategic Plan and considers future commercial space business projections. The initial cycle of the Advanced Space Transportation Program implementation planning was conducted from December 1995 through February 1996 and represented increased NASA emphasis on broad base technology development with the goal of dramatic reductions in the cost of space transportation. The second planning cycle, conducted in January and February 1997, updated the program implementation plan based on changes in the external environment, increased maturity of advanced concept studies, and current technology assessments. The program has taken a business-like approach to technology development with a balanced portfolio of near, medium, and long-term strategic targets. Strategic targets are influenced by Earth science, space science, and exploration objectives as well as commercial space markets. Commercial space markets include those that would be enhanced by lower cost transportation as well as potential markets resulting in major increases in space business induced by reductions in transportation cost. The program plan addresses earth-to-orbit space launch, earth orbit operations and deep space systems. It also addresses all critical transportation system elements; including structures, thermal protection systems, propulsion, avionics, and operations. As these technologies are matured, integrated technology flight experiments such as the X-33 and X-34 flight demonstrator programs support near-term (one to five years) development or operational decisions. The Advanced Space Transportation Program and the flight demonstrator programs combine business planning, ground-based technology demonstrations and flight demonstrations that will permit industry and NASA to commit to revolutionary new space transportation systems

Nuclear space power and propulsion requirements and issues

International Nuclear Information System (INIS)

Swerdling, M.; Isenberg, L.

1995-01-01

The use of nuclear power in space is going through a low point. The kinds of missions that would use nuclear power are expensive and there are few new expensive missions. Both NASA and DoD are in a mode of cheaper, faster, better, which means using what is available as much as possible and only incorporating new technology to reduce mission cost. NASA is performing Mission to Planet Earth and detailed exploration missions of Mars. These NASA missions can be done with solar-battery power subsystems and there is no need for nuclear power. The NASA mission to Pluto does require nuclear radioisotope power. Ways to reduce the power subsystem cost and the power level are being investigated. NASA is studying ways to explore beyond Mars with solar-battery power because of the cost and uncertainty in the availability and launchability of nuclear space power systems. The DoD missions are all in earth orbit and can be done with solar-battery systems. The major DoD requirement at present is to reduce costs of all their space missions. One way to do this is to develop highly efficient upper stage boosters that can be integrated with lower cost Earth to low orbit stages and still place their payloads in to higher orbits. One attractive upper stage is a nuclear bimodal (propulsion and power) engine to accomplished lower booster cost to place space assets in GEO. However this is not being pursued because of DOE's new policy not to fund nuclear space power research and development as well as the difficulty in obtaining launch approval for nuclear propulsion and power systems

Advanced calculus

CERN Document Server

Nickerson, HK; Steenrod, NE

2011-01-01

""This book is a radical departure from all previous concepts of advanced calculus,"" declared the Bulletin of the American Mathematics Society, ""and the nature of this departure merits serious study of the book by everyone interested in undergraduate education in mathematics."" Classroom-tested in a Princeton University honors course, it offers students a unified introduction to advanced calculus. Starting with an abstract treatment of vector spaces and linear transforms, the authors introduce a single basic derivative in an invariant form. All other derivatives - gradient, divergent, curl,

Overview and Recent Accomplishments of the Advanced Mirror Technology Development (AMTD) for Large Aperture UVOIR Space Telescopes Project

Science.gov (United States)

Stahl, H. Philip

2013-01-01

Per Astro2010, a new, larger UVO telescope is needed to answer fundamental scientific questions, such as: is there life on Earth-like exoplanets; how galaxies assemble stellar populations; how baryonic matter interacts with intergalactic medium; and how solar systems form and evolve. And, present technology is not mature enough to affordably build and launch any potential UVO concept. Advanced Mirror Technology Development (AMTD) is a funded SAT project. Our objective is to mature to TRL-6 the critical technologies needed to produce 4-m or larger flight-qualified UVOIR mirrors by 2018 so that a viable mission can be considered by the 2020 Decadal Review. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND result in a high-performance low-cost low-risk system. To provide the science community with options, we are pursuing multiple technology paths. We have assembled an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes. One of our key accomplishments is that we have derived engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicle and its inherent mass and volume constraints. We defined and initiated a program to mature 6 key technologies required to fabricate monolithic and segmented space mirrors.

The advanced thermionics initiative...program update

International Nuclear Information System (INIS)

Lamp, T.R.; Donovan, B.D.

1993-01-01

The United States Air Force has had a long standing interest in thermionic space power dating back to the early 1960s when a heat pipe cooled thermionic converter was demonstrated through work at the predecessor to Wright Laboratory (WL). With the exception of the short hiatus in the mid-70s, Air Force thermionics work at Wright Laboratory has continued to the present time with thermionic technology programs including the burst power thermionic phase change concepts, heat pipe cooled planar diodes, and advanced in-core concept developments such as composite materials, insulators and oxygenation. The Advanced Thermionics Initiative (ATI) program was organized to integrate thermionic technology advances into a converter suitable for in-core reactor applications in the 10 to 40 kWe power range. As an advanced thermionics technology program, the charter and philosophy of the ATI program is to provide the needed advanced converter concepts in support of national thermionic space power programs

Evaluating research for disruptive innovation in the space sector

Science.gov (United States)

Summerer, L.

2012-12-01

Many governmental space activities need to be planned with a time horizon that extends beyond the comfort zone of reliable technology development assessments and predictions. In an environment of accelerating technological change, a methodological approach to addressing non-core technology trends and potentially disruptive, game-changing developments not yet linked to the space sector is increasingly important to complement efforts in core technology R&D planning. Various models and organisational setups aimed at fulfilling this purpose are in existence. These include, with varying levels of relevance to space, the National Aeronautics and Space Administration (NASA) Institute for Advanced Concepts (NIAC, operational form 1998 to 2007 and recently re-established), the Defence Advanced Research Projects Agency of the US Department of Defence, the Massachusetts Institute of Technology (MIT) Medialab, the early versions of Starlab, the Lockheed Skunk Works and the European Space Agency's Advanced Concepts Team. Some of these organisations have been reviewed and assessed individually, though systematic comparison of their methods, approaches and results have not been published. This may be due in part to the relatively sparse scientific literature on organisational parameters for enabling disruptive innovation as well as to the lack of commonly agreed indicators for the evaluation of their performance. Furthermore, innovation support systems in the space sector are organised differently than in traditional, open competitive markets, which serve as the basis for most scholarly literature on the organisation of innovation. The present paper is intended to advance and stimulate discussion on the organisation of disruptive innovation mechanisms specifically for the space sector. It uses the examples of the NASA Institute for Advanced Concepts and the ESA Advanced Concepts Team, analyses their respective approaches and compares their results, leading to the proposal of

Assessing Space Exploration Technology Requirements as a First Step Towards Ensuring Technology Readiness for International Cooperation in Space Exploration

Science.gov (United States)

Laurini, Kathleen C.; Hufenbach, Bernhard; Satoh, Maoki; Piedboeuf, Jean-Claude; Neumann, Benjamin

2010-01-01

Advancing critical and enhancing technologies is considered essential to enabling sustainable and affordable human space exploration. Critical technologies are those that enable a certain class of mission, such as technologies necessary for safe landing on the Martian surface, advanced propulsion, and closed loop life support. Others enhance the mission by leading to a greater satisfaction of mission objectives or increased probability of mission success. Advanced technologies are needed to reduce mass and cost. Many space agencies have studied exploration mission architectures and scenarios with the resulting lists of critical and enhancing technologies being very similar. With this in mind, and with the recognition that human space exploration will only be enabled by agencies working together to address these challenges, interested agencies participating in the International Space Exploration Coordination Group (ISECG) have agreed to perform a technology assessment as an important step in exploring cooperation opportunities for future exploration mission scenarios. "The Global Exploration Strategy: The Framework for Coordination" was developed by fourteen space agencies and released in May 2007. Since the fall of 2008, several International Space Exploration Coordination Group (ISECG) participating space agencies have been studying concepts for human exploration of the moon. They have identified technologies considered critical and enhancing of sustainable space exploration. Technologies such as in-situ resource utilization, advanced power generation/energy storage systems, reliable dust resistant mobility systems, and closed loop life support systems are important examples. Similarly, agencies such as NASA, ESA, and Russia have studied Mars exploration missions and identified critical technologies. They recognize that human and robotic precursor missions to destinations such as LEO, moon, and near earth objects provide opportunities to demonstrate the

Design and development of the MITEE-B bi-modal nuclear propulsion engine

International Nuclear Information System (INIS)

Paniagua, John C.; Powell, James R.; Maise, George

2003-01-01

Previous studies of compact, ultra-lightweight high performance nuclear thermal propulsion engines have concentrated on systems that only deliver high thrust. However, many potential missions also require substantial amounts of electric power. Studies of a new, very compact and lightweight bi-modal nuclear engine that provides both high propulsive thrust and high electric power for planetary science missions are described. The design is a modification of the MITEE nuclear thermal engine concept that provided only high propulsive thrust. In the new design, MITEE-B, separate closed cooling circuits are incorporated into the reactor, which transfers useful amounts of thermal energy to a small power conversion system that generates continuous electric power over the full life of the mission, even when the engine is not delivering propulsive thrust. Two versions of the MITEE-B design are described and analyzed. Version 1 generates 1 kW(e) of continuous power for control of the spacecraft, sensors, data transmission, etc. This power level eliminates the need for RTG's on missions to the outer planets, and allowing considerably greater operational capability for the spacecraft. This, plus its high thrust and high specific impulse propulsive capabilities, makes MITEE-B very attractive for such missions. In Version 2, of MITEE-B, a total of 20 kW(e) is generated, enabling the use of electric propulsion. The combination of high open cycle propulsion thrust (20,000 Newtons) with a specific impulse of ∼1000 seconds for short impulse burns, and long term (months to years), electric propulsion greatly increases MITEE's ΔV capability. Version 2 of MITEE-B also enables the production and replenishment of H2 propellant using in-situ resources, such as electrolysis of water from the ice sheet on Europa and other Jovian moons. This capability would greatly increase the ΔV available for certain planetary science missions. The modifications to the MITEE multiple pressure tube

Advanced Solid State Lighting for Human Evaluation

Data.gov (United States)

National Aeronautics and Space Administration — Lighting intensity and color have a significant impact on human circadian rhythms.  Advanced solid state lighting was developed for the Advanced Exploration System...

Advanced Beamline Design for Fermilab's Advanced Superconducting Test Accelerator

Energy Technology Data Exchange (ETDEWEB)

Prokop, Christopher [Northern Illinois Univ., DeKalb, IL (United States)

2014-01-01

The Advanced Superconducting Test Accelerator (ASTA) at Fermilab is a new electron accelerator currently in the commissioning stage. In addition to testing superconducting accelerating cavities for future accelerators, it is foreseen to support a variety of Advanced Accelerator R&D (AARD) experiments. Producing the required electron bunches with the expected flexibility is challenging. The goal of this dissertation is to explore via numerical simulations new accelerator beamlines that can enable the advanced manipulation of electron bunches. The work especially includes the design of a low-energy bunch compressor and a study of transverse-to-longitudinal phase space exchangers.

Datation U_Pb : âge de mise en place du magmatisme bimodal des Jebilet centrales (chaîne Varisque, Maroc). Implications géodynamiquesU_Pb dating: emplacement age of the bimodal magmatism of central Jebilet (Variscan Belt, Morocco). Geodynamic implications

Science.gov (United States)

Essaifi, Abderrahim; Potrel, Alain; Capdevila, Ramon; Lagarde, Jean-Louis

2003-01-01

The bimodal magmatism of central Jebilet is dated to 330.5 +0.68-0.83 Ma by UPb dating on zircons. This age, similar to that of the syntectonic Jebilet cordierite-bearing granitoids, corresponds to the age of the local major tectonometamorphic event. The syntectonic plutonism of the Jebilet massif, composed of tholeiitic, alkaline, and peraluminous calc-alkaline series, is variegated. Magmas emplacement was favoured by the local extension induced by the motion along the western boundary of the Carboniferous basins of the Moroccan Meseta. The Jebilet massif exemplifies the activation of various magmas sources during an episode of continental convergence and crustal wrenching.

Advanced Electric Propulsion NextSTEP BAA Activity

Data.gov (United States)

National Aeronautics and Space Administration — The goal of the AES Advanced Electric Propulsion Next Space Technologies for Exploration Partnerships (NextSTEP) Broad Agency Announcement (BAA) activity is to...

Space tug applications. Final report

International Nuclear Information System (INIS)

1996-01-01

This article is the final report of the conceptual design efforts for a 'space tug'. It includes preliminary efforts, mission analysis, configuration analysis, impact analysis, and conclusions. Of the several concepts evaluated, the nuclear bimodal tug was one of the top candidates, with the two options being the NEBA-1 and NEBA-3 systems. Several potential tug benefits were identified during the mission analysis. The tug enables delivery of large (>3,500 kg) payloads to the outer planets and it increases the GSO delivery capability by 20% relative to current systems. By providing end of life disposal, the tug can be used to extend the life of existing space assets. It can also be used to reboost satellites which were not delivered to their final orbit by the launch system. A specific mission model is the key to validating the tug concept. Once a mission model can be established, mission analysis can be used to determine more precise propellant quantities and burn times. In addition, the specific payloads can be evaluated for mass and volume capability with the launch systems. Results of the economic analysis will be dependent on the total years of operations and the number of missions in the mission model. The mission applications evaluated during this phase drove the need for large propellant quantities and thus did not allow the payloads to step down to smaller and less expensive launch systems

Recent advances in nuclear powered electric propulsion for space exploration

International Nuclear Information System (INIS)

Cassady, R. Joseph; Frisbee, Robert H.; Gilland, James H.; Houts, Michael G.; LaPointe, Michael R.; Maresse-Reading, Colleen M.; Oleson, Steven R.; Polk, James E.; Russell, Derrek; Sengupta, Anita

2008-01-01

Nuclear and radioisotope powered electric thrusters are being developed as primary in space propulsion systems for potential future robotic and piloted space missions. Possible applications for high-power nuclear electric propulsion include orbit raising and maneuvering of large space platforms, lunar and Mars cargo transport, asteroid rendezvous and sample return, and robotic and piloted planetary missions, while lower power radioisotope electric propulsion could significantly enhance or enable some future robotic deep space science missions. This paper provides an overview of recent US high-power electric thruster research programs, describing the operating principles, challenges, and status of each technology. Mission analysis is presented that compares the benefits and performance of each thruster type for high priority NASA missions. The status of space nuclear power systems for high-power electric propulsion is presented. The paper concludes with a discussion of power and thruster development strategies for future radioisotope electric propulsion systems

Recent advances in nuclear powered electric propulsion for space exploration

Energy Technology Data Exchange (ETDEWEB)

Cassady, R. Joseph [Aerojet Corp., Redmond, CA (United States); Frisbee, Robert H. [Jet Propulsion Laboratory, Pasadena, CA (United States); Gilland, James H. [Ohio Aerospace Institute, Cleveland, OH (United States); Houts, Michael G. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); LaPointe, Michael R. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)], E-mail: michael.r.lapointe@nasa.gov; Maresse-Reading, Colleen M. [Jet Propulsion Laboratory, Pasadena, CA (United States); Oleson, Steven R. [NASA Glenn Research Center, Cleveland, OH (United States); Polk, James E. [Jet Propulsion Laboratory, Pasadena, CA (United States); Russell, Derrek [Northrop Grumman Space Technology, Redondo Beach, CA (United States); Sengupta, Anita [Jet Propulsion Laboratory, Pasadena, CA (United States)

2008-03-15

Nuclear and radioisotope powered electric thrusters are being developed as primary in space propulsion systems for potential future robotic and piloted space missions. Possible applications for high-power nuclear electric propulsion include orbit raising and maneuvering of large space platforms, lunar and Mars cargo transport, asteroid rendezvous and sample return, and robotic and piloted planetary missions, while lower power radioisotope electric propulsion could significantly enhance or enable some future robotic deep space science missions. This paper provides an overview of recent US high-power electric thruster research programs, describing the operating principles, challenges, and status of each technology. Mission analysis is presented that compares the benefits and performance of each thruster type for high priority NASA missions. The status of space nuclear power systems for high-power electric propulsion is presented. The paper concludes with a discussion of power and thruster development strategies for future radioisotope electric propulsion systems.

Achievable space elevators for space transportation and starship acceleration

Science.gov (United States)

Pearson, Jerome

1990-04-01

Space elevator concepts for low-cost space launches are reviewed. Previous concepts suffered from requirements for ultra-high-strength materials, dynamically unstable systems, or from danger of collision with space debris. The use of magnetic grain streams solves these problems. Magnetic grain streams can support short space elevators for lifting payloads cheaply into Earth orbit, overcoming the material strength problem in building space elevators. Alternatively, the stream could support an international spaceport circling the Earth daily tens of miles above the equator, accessible to advanced aircraft. Mars could be equipped with a similar grain stream, using material from its moons Phobos and Deimos. Grain-stream arcs about the sun could be used for fast launches to the outer planets and for accelerating starships to near lightspeed for interstellar reconnaisance. Grain streams are essentially impervious to collisions, and could reduce the cost of space transportation by an order of magnitude.

Space Life Sciences Research: The Importance of Long-Term Space Experiments

Science.gov (United States)

1993-01-01

This report focuses on the scientific importance of long-term space experiments for the advancement of biological science and the benefit of humankind. It includes a collection of papers that explore the scientific potential provided by the capability to manipulate organisms by removing a force that has been instrumental in the evolution and development of all organisms. Further, it provides the scientific justification for why the long-term space exposure that can be provided by a space station is essential to conduct significant research.

Advanced Stirling Convertor (ASC-E2) Characterization Testing

Science.gov (United States)

Williams, Zachary D.; Oriti, Salvatore M.

2012-01-01

Testing has been conducted on Advanced Stirling Convertors (ASCs)-E2 at NASA Glenn Research Center in support of the Advanced Stirling Radioisotope Generator (ASRG) project. This testing has been conducted to understand sensitivities of convertor parameters due to environmental and operational changes during operation of the ASRG in missions to space. This paper summarizes test results and explains the operation of the ASRG during space missions

Advanced Life Support Project: Crop Experiments at Kennedy Space Center

Science.gov (United States)

Sager, John C.; Stutte, Gary W.; Wheeler, Raymond M.; Yorio, Neil

2004-01-01

Crop production systems provide bioregenerative technologies to complement human crew life support requirements on long duration space missions. Kennedy Space Center has lead NASA's research on crop production systems that produce high value fresh foods, provide atmospheric regeneration, and perform water processing. As the emphasis on early missions to Mars has developed, our research focused on modular, scalable systems for transit missions, which can be developed into larger autonomous, bioregenerative systems for subsequent surface missions. Components of these scalable systems will include development of efficient light generating or collecting technologies, low mass plant growth chambers, and capability to operate in the high energy background radiation and reduced atmospheric pressures of space. These systems will be integrated with air, water, and thermal subsystems in an operational system. Extensive crop testing has been done for both staple and salad crops, but limited data is available on specific cultivar selection and breadboard testing to meet nominal Mars mission profiles of a 500-600 day surface mission. The recent research emphasis at Kennedy Space Center has shifted from staple crops, such as wheat, soybean and rice, toward short cycle salad crops such as lettuce, onion, radish, tomato, pepper, and strawberry. This paper will review the results of crop experiments to support the Exploration Initiative and the ongoing development of supporting technologies, and give an overview of capabilities of the newly opened Space Life Science (SLS) Lab at Kennedy Space Center. The 9662 square m (104,000 square ft) SLS Lab was built by the State of Florida and supports all NASA research that had been performed in Hanger-L. In addition to NASA research, the SLS Lab houses the Florida Space Research Institute (FSRI), responsible for co-managing the facility, and the University of Florida (UF) has established the Space Agriculture and Biotechnology Research and

High Performance Thrusters for Advanced Green Monopropellants, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The development of an advanced green monopropellant propulsion system could have significant benefits to a wide range of NASA space missions, from deep space...

NASA Space Environments Technical Discipline Team Space Weather Activities

Science.gov (United States)

Minow, J. I.; Nicholas, A. C.; Parker, L. N.; Xapsos, M.; Walker, P. W.; Stauffer, C.

2017-12-01

The Space Environment Technical Discipline Team (TDT) is a technical organization led by NASA's Technical Fellow for Space Environments that supports NASA's Office of the Chief Engineer through the NASA Engineering and Safety Center. The Space Environments TDT conducts independent technical assessments related to the space environment and space weather impacts on spacecraft for NASA programs and provides technical expertise to NASA management and programs where required. This presentation will highlight the status of applied space weather activities within the Space Environment TDT that support development of operational space weather applications and a better understanding of the impacts of space weather on space systems. We will first discuss a tool that has been developed for evaluating space weather launch constraints that are used to protect launch vehicles from hazardous space weather. We then describe an effort to better characterize three-dimensional radiation transport for CubeSat spacecraft and processing of micro-dosimeter data from the International Space Station which the team plans to make available to the space science community. Finally, we will conclude with a quick description of an effort to maintain access to the real-time solar wind data provided by the Advanced Composition Explorer satellite at the Sun-Earth L1 point.

Space Weather and Real-Time Monitoring

Directory of Open Access Journals (Sweden)

S Watari

2009-04-01

Full Text Available Recent advance of information and communications technology enables to collect a large amount of ground-based and space-based observation data in real-time. The real-time data realize nowcast of space weather. This paper reports a history of space weather by the International Space Environment Service (ISES in association with the International Geophysical Year (IGY and importance of real-time monitoring in space weather.

Bi-modal stimulation in the treatment of tinnitus: a study protocol for an exploratory trial to optimise stimulation parameters and patient subtyping.

Science.gov (United States)

D'Arcy, Shona; Hamilton, Caroline; Hughes, Stephen; Hall, Deborah A; Vanneste, Sven; Langguth, Berthold; Conlon, Brendan

2017-10-25

Tinnitus is the perception of sound in the absence of a corresponding external acoustic stimulus. Bimodal neuromodulation is emerging as a promising treatment for this condition. The main objectives of this study are to investigate the relevance of interstimulus timing and the choices of acoustic and tongue stimuli for a proprietary bimodal (auditory and somatosensory) neuromodulation device, as well as to explore whether specific subtypes of patients are differentially responsive to this novel intervention for reducing the symptoms of chronic tinnitus. This is a two-site, randomised, triple-blind, exploratory study of a proprietary neuromodulation device with a pre-post and 12-month follow-up design. Three different bimodal stimulation parameter sets will be examined. The study will enrol 342 patients, split 80:20 between two sites (Dublin, Ireland and Regensburg, Germany), to complete 12 weeks of treatment with the device. Patients will be allocated to one of three arms using a stepwise stratification according to four binary categories: tinnitus tonality, sound level tolerance (using loudness discomfort level of Tinnitus Handicap Inventory and the Tinnitus Functional Index, after 12 weeks of intervention. Clinical efficacy will be further explored in a series of patient subtypes, split by the stratification variables and by presence of a somatic tinnitus. Evidence for sustained effects on the psychological and functional impact of tinnitus will be followed up for 12 months. Safety data will be collected and reported. A number of feasibility measures to inform future trial design include: reasons for exclusion, completeness of data collection, attrition rates, patient's adherence to the device usage as per manufacturer's instructions and evaluation of alternative methods for estimating tinnitus impact and tinnitus loudness. This study protocol is approved by the Tallaght Hospital/St. James's Hospital Joint Research Ethics Committee in Dublin, Ireland, and by the

Advance of Wetting Front in Silt Loam Soil

Directory of Open Access Journals (Sweden)

Mohamed Mahmood

2013-04-01

Full Text Available Under drip irrigation , the plant's root is concentrated inside the wetted bulb (region. Thus, the development of these roots and the plant production are greatly affected by the wetting pattern. Therefore, the wetting pattern of soil under drip irrigation must be taken into consideration in the design of drip irrigation system for both single dripping source or multi-overlapping wetting patterns of dripping water sources.2The aim of this study is to evaluate the effect of initial water content of the soil and spacing between two adjacent dripping sources with different flow rate on the movement of the wetting front.This study included 16 tests for monitoring the advancement of the wetting front with time during and after the water application phase. The water advance and water distribution measurement are carried out for two cases of the soil profile: for the first case with initial volumetric water content of 4.08% and for the second case with initial volumetric water content of 12.24%. Two spacing between the emitter were tested 25cm and 50 cm using application flow rates of 0.606, 1.212, 1.818, and 2.424 cm3 /min/cm to show the combined effect of spacing and flow rate on the performance of two adjacent emitter.The study proposed a method for determining the spacing between the two emitting sources , the water application rate and watering time. The proposed method depends on a wetted zone whose depth is equal to the root zone depth with a values equals to the maximum vertical advance of the wetting front underneath the drip line at time when this depth is equal to the depth of wetting at mid­point between the drip line. the study revealed that both the vertical water advance in soil underneath the emitter and the horizontal advance of the wetting front is larger than those in the case of single emitter.Furthermore, the vertical water advance increases with the decrease spacing between the two drip lines. Also, the horizontal advance of the

Proceedings of the 2006 international congress on advances in nuclear power plants - ICAPP'06

International Nuclear Information System (INIS)

2006-01-01

reliability improvements, outage optimization, human factors, plant staffing, outage reduction features, major component reliability, repair and replacement, in-service inspection, and codes and standards. - 5. Plant Safety Assessment and Regulatory Issues Transient and accident performance including LOCA and non-LOCA, severe accident analysis, impact of risk informed changes, accident management, assessment and management of aging, degradation and damage, life extension lessons from plant operations, probabilistic safety assessment, plant safety analysis, reliability engineering, operating and future plants. - 6. Thermal Hydraulic Analysis and Testing Phenomena identification and ranking, computer code scaling applicability and uncertainty, containment thermal hydraulics, component and integral system tests, improved code development and qualification, single and two phase flow; advanced computational thermal hydraulic methods. - 7. Core and Fuel Cycle Concepts and Experiments Core physics, advances in computational reactor analysis, in-core fuel management, mixed-oxide fuel, thorium fuel cycle, low moderation cores, high conversion reactor designs, particle and pebble bed fuel design, testing and reliability; fuel cycle waste minimization, recycle, storage and disposal. - 8. Materials and Structural Issues Fuel, core, RPV and internals structures, advanced materials issues and fracture mechanics, concrete and steel containments, space structures, analysis, design and monitoring for seismic, dynamic and extreme accidents; irradiation issues and materials for new plants. - 9. Nuclear Energy and Sustainability including Hydrogen, Desalination and Other Applications Environmental impact of nuclear and alternative systems, spent fuel dispositions and transmutation systems, fully integrated fuel cycle and symbiotic nuclear power systems, application of advanced designs to non-power applications such as the production of hydrogen, sea water desalination, heating and other co

Affordable Bimodal Optical Sensors to Spread the Use of Automated Insect Monitoring

Directory of Open Access Journals (Sweden)

Ilyas Potamitis

2018-01-01

Full Text Available We present a novel bimodal optoelectronic sensor based on Fresnel lenses and the associated stereo-recording device that records the wingbeat event of an insect in flight as backscattered and extinction light. We investigate the complementary information of these two sources of biometric evidence and we finally embed part of this technology in an electronic e-trap for fruit flies. The e-trap examines the spectral content of the wingbeat of the insect flying in and reports wirelessly counts and species identity. We design our devices so that they are optimized in terms of detection accuracy and power consumption, but above all, we ensure that they are affordable. Our aim is to make more widespread the use of electronic insect traps that report in virtually real time the level of the pest population from the field straight to a human controlled agency. We have the vision to establish remote automated monitoring for all insects of economic and hygienic importance at large spatial scales, using their wingbeat as biometric evidence. To this end, we provide open access to the implementation details, recordings, and classification code we developed.

Single-crystal 40Ar/39Ar incremental heating reveals bimodal sanidine ages in the Bishop Tuff

Science.gov (United States)

Andersen, N. L.; Jicha, B. R.; Singer, B. S.

2015-12-01

The 650 km3 Bishop Tuff (BT) is among the most studied volcanic deposits because it is an extensive marker bed deposited just after the Matuyama-Brunhes boundary. Reconstructions of the vast BT magma reservoir from which high-silica rhyolite erupted have long influenced thinking about how large silicic magma systems are assembled, crystallized, and mixed. Yet, the longevity of the high silica rhyolitic melt and exact timing of the eruption remain controversial due to recent conflicting 40Ar/39Ar sanidine vs. SIMS and ID-TIMS U-Pb zircon dates. We have undertaken 21 40Ar/39Ar incremental heating ages on 2 mm BT sanidine crystals from pumice in 3 widely separated outcrops of early-erupted fall and flow units. Plateau ages yield a bimodal distribution: a younger group has a mean of 766 ka and an older group gives a range between 772 and 782 ka. The younger population is concordant with the youngest ID-TIMS and SIMS U-Pb zircon ages recently published, as well as the astronomical age of BT in marine sediment. Of 21 crystals, 17 yield older, non-plateau, steps likely affected by excess Ar that would bias traditional 40Ar/39Ar total crystal fusion ages. The small spread in older sanidine ages, together with 25+ kyr of pre-eruptive zircon growth, suggest that the older sanidines are not partially outgassed xenocrysts. A bimodal 40Ar/39Ar age distribution implies that some fraction of rhyolitic melt cooled below the Ar closure temperature at least 10 ky prior to eruption. We propose that rapid "thawing" of a crystalline mush layer released older crystals into rhyolitic melt from which sanidine also nucleated and grew immediately prior to the eruption. High precision 40Ar/39Ar dating can thus provide essential information on thermo-physical processes at the millenial time scale that are critical to interpreting U-Pb zircon age distributions that are complicated by large uncertainties associated with zircon-melt U-Th systematics.

Human Research Program: Space Human Factors and Habitability Element

Science.gov (United States)

Russo, Dane M.

2007-01-01

The three project areas of the Space Human Factors and Habitability Element work together to achieve a working and living environment that will keep crews healthy, safe, and productive throughout all missions -- from Earth orbit to Mars expeditions. The Advanced Environmental Health (AEH) Project develops and evaluates advanced habitability systems and establishes requirements and health standards for exploration missions. The Space Human Factors Engineering (SHFE) Project s goal is to ensure a safe and productive environment for humans in space. With missions using new technologies at an ever-increasing rate, it is imperative that these advances enhance crew performance without increasing stress or risk. The ultimate goal of Advanced Food Technology (AFT) Project is to develop and deliver technologies for human centered spacecraft that will support crews on missions to the moon, Mars, and beyond.

Biocompatible branched copolymer nanoparticles prepared by RAFT polymerization as MRI/PET bimodal tracers

Energy Technology Data Exchange (ETDEWEB)

Yang, Chang-Tong [Lee Kong Chian School of Medicine, Nanyang Technological University (Singapore); Tao, He; Jackson, Alexander W [Institute of Chemical and Engineering Sciences, Agency for Science Technology and Research (Singapore); Chandrasekharan, Prashant [Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Agency for Science Technology and Research (Singapore); Padmanabhan, Parasuraman [Lee Kong Chian School of Medicine, Nanyang Technological University (Singapore); Gulyás, Balázs; Halldin, Christer [Lee Kong Chian School of Medicine, Nanyang Technological University (Singapore); Karolinska Institutet, Department of Clinical Neuroscience, Stockholm (Sweden)

2015-05-18

Stable branched copolymer nanoparticles of varying size (Dh = 20 – 35 nm) have been developed and employed as MRI nano-sized contrast agents. RAFT polymerization has been employed to prepare these novel nanoparticles possessing DO3A macrocycles within their cores and succinimidyl ester benzoate functionalities within their coronas. It has been demonstrated that these nanoparticles can chelate gadolinium and in vitro cytotoxicity studies using HK-2 cells established their negligible toxicity profile. In vivo MRI experiments showed that these nanoparticles have a high relaxivity and a long blood retention time. Xenograft experiments further illustrated the ability of these nanoparticles to perfuse and passively accumulate in tumor cells, presumably through the enhanced EPR effect. The presence of the succinimidyl ester benzoate functionalities within the nanoparticle coronas will permit future surface modification with fluorophores or targeting moieties to generate nanoparticles to study opportunities for bimodal imaging nano-probes or active cell targeting contrast agents. The chelation with PET radioisotopes (68Ga(III) or 64Cu(II)) can afford various PET tracers.

Elementary excitations and the phase transition in the bimodal Ising spin glass model

International Nuclear Information System (INIS)

Jinuntuya, N; Poulter, J

2012-01-01

We show how the nature of the phase transition in the two-dimensional bimodal Ising spin glass model can be understood in terms of elementary excitations. Although the energy gap with the ground state is expected to be 4J in the ferromagnetic phase, a gap 2J is in fact found if the finite lattice is wound around a cylinder of odd circumference L. This 2J gap is really a finite size effect that should not occur in the thermodynamic limit of the ferromagnet. The spatial influence of the frustration must be limited and not wrap around the system if L is large enough. In essence, the absence of 2J excitations defines the ferromagnetic phase without recourse to calculating the magnetization or investigating the system response to domain wall defects. This study directly investigates the response to temperature. We also estimate the defect concentration where the phase transition to the spin glass state occurs. The value p c = 0.1045(11) is in reasonable agreement with the literature

Biocompatible branched copolymer nanoparticles prepared by RAFT polymerization as MRI/PET bimodal tracers

International Nuclear Information System (INIS)

Yang, Chang-Tong; Tao, He; Jackson, Alexander W; Chandrasekharan, Prashant; Padmanabhan, Parasuraman; Gulyás, Balázs; Halldin, Christer

2015-01-01

Stable branched copolymer nanoparticles of varying size (Dh = 20 – 35 nm) have been developed and employed as MRI nano-sized contrast agents. RAFT polymerization has been employed to prepare these novel nanoparticles possessing DO3A macrocycles within their cores and succinimidyl ester benzoate functionalities within their coronas. It has been demonstrated that these nanoparticles can chelate gadolinium and in vitro cytotoxicity studies using HK-2 cells established their negligible toxicity profile. In vivo MRI experiments showed that these nanoparticles have a high relaxivity and a long blood retention time. Xenograft experiments further illustrated the ability of these nanoparticles to perfuse and passively accumulate in tumor cells, presumably through the enhanced EPR effect. The presence of the succinimidyl ester benzoate functionalities within the nanoparticle coronas will permit future surface modification with fluorophores or targeting moieties to generate nanoparticles to study opportunities for bimodal imaging nano-probes or active cell targeting contrast agents. The chelation with PET radioisotopes (68Ga(III) or 64Cu(II)) can afford various PET tracers.

The quantum transverse spin-2 Ising model with a bimodal random-field in the pair approximation

International Nuclear Information System (INIS)

Canko, O.; Albayrak, E.; Keskin, M.

2005-01-01

In this paper, we have investigated the bimodal random-field spin-2 Ising system in a transverse field by combining the pair approximation with the discretized path-integral representation. The exact equations for the second-order phase transition lines and tricritical points are obtained in terms of the random field H, the transverse field G and the coordination number z. It is found that there are some critical values for H and G where the tricritical points disappear for given z. We have also observed that the system presents reentrant behavior which may be caused by the quantum effects and randomness. The phase diagram with respect to the random field and the second-order phase transition temperature are studied extensively for given values of the transverse field and the coordination number

Modern methods in topological vector spaces

CERN Document Server

Wilansky, Albert

2013-01-01

Designed for a one-year course in topological vector spaces, this text is geared toward advanced undergraduates and beginning graduate students of mathematics. The subjects involve properties employed by researchers in classical analysis, differential and integral equations, distributions, summability, and classical Banach and Frechét spaces. Optional problems with hints and references introduce non-locally convex spaces, Köthe-Toeplitz spaces, Banach algebra, sequentially barrelled spaces, and norming subspaces.Extensive introductory chapters cover metric ideas, Banach space, topological vect

IASM: Individualized activity space modeler

Science.gov (United States)

Hasanzadeh, Kamyar

2018-01-01

Researchers from various disciplines have long been interested in analyzing and describing human mobility patterns. Activity space (AS), defined as an area encapsulating daily human mobility and activities, has been at the center of this interest. However, given the applied nature of research in this field and the complexity that advanced geographical modeling can pose to its users, the proposed models remain simplistic and inaccurate in many cases. Individualized Activity Space Modeler (IASM) is a geographic information system (GIS) toolbox, written in Python programming language using ESRI's Arcpy module, comprising four tools aiming to facilitate the use of advanced activity space models in empirical research. IASM provides individual-based and context-sensitive tools to estimate home range distances, delineate activity spaces, and model place exposures using individualized geographical data. In this paper, we describe the design and functionality of IASM, and provide an example of how it performs on a spatial dataset collected through an online map-based survey.

Space power systems--''Spacecraft 2000''

International Nuclear Information System (INIS)

Faymon, K.A.

1985-01-01

The National Space programs of the 21st century will require abundant and relatively low cost power and energy produced by high reliability-low mass systems. Advancement of current power system related technologies will enable the U.S. to realize increased scientific payload for government missions or increased revenue producing payload for commercial space endeavors. Autonomous, unattended operation will be a highly desirable characteristic of these advanced power systems. Those space power-energy related technologies, which will comprise the space craft of the late 1990's and the early 2000's, will evolve from today's state-of-the-art systems and those long term technology development programs presently in place. However, to foster accelerated development of the more critical technologies which have the potential for high-payoffs, additional programs will be proposed and put in place between now and the end of the century. Such a program is ''Spacecraft 2000'', which is described in this paper

Radiation hardening of optical fibers and fiber sensors for space applications: recent advances

Science.gov (United States)

Girard, S.; Ouerdane, Y.; Pinsard, E.; Laurent, A.; Ladaci, A.; Robin, T.; Cadier, B.; Mescia, L.; Boukenter, A.

2017-11-01

In these ICSO proceedings, we review recent advances from our group concerning the radiation hardening of optical fiber and fiber-based sensors for space applications and compare their benefits to state-of-the-art results. We focus on the various approaches we developed to enhance the radiation tolerance of two classes of optical fibers doped with rare-earths: the erbium (Er)-doped ones and the ytterbium/erbium (Er/Yb)-doped ones. As a first approach, we work at the component level, optimizing the fiber structure and composition to reduce their intrinsically high radiation sensitivities. For the Erbium-doped fibers, this has been achieved using a new structure for the fiber that is called Hole-Assisted Carbon Coated (HACC) optical fibers whereas for the Er/Ybdoped optical fibers, their hardening was successfully achieved adding to the fiber, the Cerium element, that prevents the formation of the radiation-induced point defects responsible for the radiation induced attenuation in the infrared part of the spectrum. These fibers are used as part of more complex systems like amplifiers (Erbium-doped Fiber Amplifier, EDFA or Yb-EDFA) or source (Erbium-doped Fiber Source, EDFS or Yb- EDFS), we discuss the impact of using radiation-hardened fibers on the system radiation vulnerability and demonstrate the resistance of these systems to radiation constraints associated with today and future space missions. Finally, we will discuss another radiation hardening approach build in our group and based on a hardening-by-system strategy in which the amplifier is optimized during its elaboration for its future mission considering the radiation effects and not in-lab.

Nuclear Space Power Systems Materials Requirements

International Nuclear Information System (INIS)

Buckman, R.W. Jr.

2004-01-01

High specific energy is required for space nuclear power systems. This generally means high operating temperatures and the only alloy class of materials available for construction of such systems are the refractory metals niobium, tantalum, molybdenum and tungsten. The refractory metals in the past have been the construction materials selected for nuclear space power systems. The objective of this paper will be to review the past history and requirements for space nuclear power systems from the early 1960's through the SP-100 program. Also presented will be the past and present status of refractory metal alloy technology and what will be needed to support the next advanced nuclear space power system. The next generation of advanced nuclear space power systems can benefit from the review of this past experience. Because of a decline in the refractory metal industry in the United States, ready availability of specific refractory metal alloys is limited

Advanced Fire Detector for Space Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Reliable and efficient fire detection is a precondition for safe spaceflight. The threat of onboard fire is constant and requires early, fast and unfailing...

The Vulcan Advanced Hybrid Manufacturing System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Made In Space is developing the The Vulcan Advanced Hybrid Manufacturing System (VULCAN) to address NASA's requirement to produce high-strength, high-precision...

Advanced TCCS for Spacesuit Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A recent trade study showed that active removal of ammonia (NH3) and formaldehyde (CH2O) is crticial to meeting the 24-hr SMAC limits in the advanced space suit...

Overview of Phase Space Manipulations of Relativistic Electron Beams

Energy Technology Data Exchange (ETDEWEB)

Xiang, Dao; /SLAC

2012-08-31

Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R&D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.

Overview of Phase Space Manipulations of Relativistic Electron Beams

International Nuclear Information System (INIS)

Xiang, Dao

2012-01-01

Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R and D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.

The Advanced Technology Operations System: ATOS

Science.gov (United States)

Kaufeler, J.-F.; Laue, H. A.; Poulter, K.; Smith, H.

1993-01-01

Mission control systems supporting new space missions face ever-increasing requirements in terms of functionality, performance, reliability and efficiency. Modern data processing technology is providing the means to meet these requirements in new systems under development. During the past few years the European Space Operations Centre (ESOC) of the European Space Agency (ESA) has carried out a number of projects to demonstrate the feasibility of using advanced software technology, in particular, knowledge based systems, to support mission operations. A number of advances must be achieved before these techniques can be moved towards operational use in future missions, namely, integration of the applications into a single system framework and generalization of the applications so that they are mission independent. In order to achieve this goal, ESA initiated the Advanced Technology Operations System (ATOS) program, which will develop the infrastructure to support advanced software technology in mission operations, and provide applications modules to initially support: Mission Preparation, Mission Planning, Computer Assisted Operations, and Advanced Training. The first phase of the ATOS program is tasked with the goal of designing and prototyping the necessary system infrastructure to support the rest of the program. The major components of the ATOS architecture is presented. This architecture relies on the concept of a Mission Information Base (MIB) as the repository for all information and knowledge which will be used by the advanced application modules in future mission control systems. The MIB is being designed to exploit the latest in database and knowledge representation technology in an open and distributed system. In conclusion the technological and implementation challenges expected to be encountered, as well as the future plans and time scale of the project, are presented.

Space Synthetic Biology (SSB)

Data.gov (United States)

National Aeronautics and Space Administration — This project focused on employing advanced biological engineering and bioelectrochemical reactor systems to increase life support loop closure and in situ resource...

Advancing Translational Space Research Through Biospecimen Sharing: Amplified Impact of Studies Utilizing Analogue Space Platforms

Science.gov (United States)

Staten, B.; Moyer, E.; Vizir, V.; Gompf, H.; Hoban-Higgins, T.; Lewis, L.; Ronca, A.; Fuller, C. A.

2016-01-01

Biospecimen Sharing Programs (BSPs) have been organized by NASA Ames Research Center since the 1960s with the goal of maximizing utilization and scientific return from rare, complex and costly spaceflight experiments. BSPs involve acquiring otherwise unused biological specimens from primary space research experiments for distribution to secondary experiments. Here we describe a collaboration leveraging Ames expertise in biospecimen sharing to magnify the scientific impact of research informing astronaut health funded by the NASA Human Research Program (HRP) Human Health Countermeasures (HHC) Element. The concept expands biospecimen sharing to one-off ground-based studies utilizing analogue space platforms (e.g., Hindlimb Unloading (HLU), Artificial Gravity) for rodent experiments, thereby significantly broadening the range of research opportunities with translational relevance for protecting human health in space and on Earth.

NASA Space Technology Roadmaps and Priorities: Restoring NASA's Technological Edge and Paving the Way for a New Era in Space

Science.gov (United States)

2012-01-01

Success in executing future NASA space missions will depend on advanced technology developments that should already be underway. It has been years since NASA has had a vigorous, broad-based program in advanced space technology development, and NASA's technology base is largely depleted. As noted in a recent National Research Council report on the U.S. civil space program: Future U.S. leadership in space requires a foundation of sustained technology advances that can enable the development of more capable, reliable, and lower-cost spacecraft and launch vehicles to achieve space program goals. A strong advanced technology development foundation is needed also to enhance technology readiness of new missions, mitigate their technological risks, improve the quality of cost estimates, and thereby contribute to better overall mission cost management. Yet financial support for this technology base has eroded over the years. The United States is now living on the innovation funded in the past and has an obligation to replenish this foundational element. NASA has developed a draft set of technology roadmaps to guide the development of space technologies under the leadership of the NASA Office of the Chief Technologist. The NRC appointed the Steering Committee for NASA Technology Roadmaps and six panels to evaluate the draft roadmaps, recommend improvements, and prioritize the technologies within each and among all of the technology areas as NASA finalizes the roadmaps. The steering committee is encouraged by the initiative NASA has taken through the Office of the Chief Technologist (OCT) to develop technology roadmaps and to seek input from the aerospace technical community with this study.

KSC ADVANCED GROUND BASED FIELD MILL V1

Data.gov (United States)

National Aeronautics and Space Administration — The Advanced Ground Based Field Mill (AGBFM) network consists of 34 (31 operational) field mills located at Kennedy Space Center (KSC), Florida. The field mills...

A novel Generalized State-Space Averaging (GSSA) model for advanced aircraft electric power systems

International Nuclear Information System (INIS)

Ebrahimi, Hadi; El-Kishky, Hassan

2015-01-01

Highlights: • A study model is developed for aircraft electric power systems. • A novel GSSA model is developed for the interconnected power grid. • The system’s dynamics are characterized under various conditions. • The averaged results are compared and verified with the actual model. • The obtained measured values are validated with available aircraft standards. - Abstract: The growing complexity of Advanced Aircraft Electric Power Systems (AAEPS) has made conventional state-space averaging models inadequate for systems analysis and characterization. This paper presents a novel Generalized State-Space Averaging (GSSA) model for the system analysis, control and characterization of AAEPS. The primary objective of this paper is to introduce a mathematically elegant and computationally simple model to copy the AAEPS behavior at the critical nodes of the electric grid. Also, to reduce some or all of the drawbacks (complexity, cost, simulation time…, etc) associated with sensor-based monitoring and computer aided design software simulations popularly used for AAEPS characterization. It is shown in this paper that the GSSA approach overcomes the limitations of the conventional state-space averaging method, which fails to predict the behavior of AC signals in a circuit analysis. Unlike conventional averaging method, the GSSA model presented in this paper includes both DC and AC components. This would capture the key dynamic and steady-state characteristics of the aircraft electric systems. The developed model is then examined for the aircraft system’s visualization and accuracy of computation under different loading scenarios. Through several case studies, the applicability and effectiveness of the GSSA method is verified by comparing to the actual real-time simulation model obtained from Powersim 9 (PSIM9) software environment. The simulations results represent voltage, current and load power at the major nodes of the AAEPS. It has been demonstrated that

Advanced Small Free-Piston Stirling Convertors for Space Power Applications

Science.gov (United States)

Wood, J. Gary; Lane, Neill

2004-02-01

This paper reports on the current status of an advanced 35 We free-piston Stirling convertor currently being developed under NASA SBIR Phase II funding. Also described is a further advanced and higher performance ~80 watt free-piston convertor being developed by Sunpower and Boeing/Rocketdyne for NASA under NRA funding. Exceptional overall convertor (engine plus linear alternator) thermodynamic performance (greater than 50% of Carnot) with specific powers around 100 We /kg appear reasonable at these low power levels.

In-Space Propulsion Technologies for Robotic Exploration of the Solar System

Science.gov (United States)

Johnson, Les; Meyer, Rae Ann; Frame, Kyle

2006-01-01

Supporting NASA's Science Mission Directorate, the In-Space Propulsion Technology Program is developing the next generation of space propulsion technologies for robotic, deep-space exploration. Recent technological advancements and demonstrations of key, high-payoff propulsion technologies have been achieved and will be described. Technologies under development and test include aerocapture, solar electric propulsion, solar sail propulsion, and advanced chemical propulsion.

An Adaptive Regulator for Space Teleoperation System in Task Space

Directory of Open Access Journals (Sweden)

Chao Ge

2014-01-01

Full Text Available The problem of the gravity information which can not be obtained in advance for bilateral teleoperation is studied. In outer space exploration, the gravity term changes with the position changing of the slave manipulator. So it is necessary to design an adaptive regulator controller to compensate for the unknown gravity signal. Moreover, to get a more accurate position tracking performance, the controller is designed in the task space instead of the joint space. Additionally, the time delay considered in this paper is not only time varying but also unsymmetrical. Finally, simulations are presented to show the effectiveness of the proposed approach.

Advanced 3D Object Identification System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Optra will build an Advanced 3D Object Identification System utilizing three or more high resolution imagers spaced around a launch platform. Data from each imager...

Innovative concept for an ultra-small nuclear thermal rocket utilizing a new moderated reactor

Energy Technology Data Exchange (ETDEWEB)

Nam, Seung Hyun; Venneri, Paolo; Kim, Yong Hee; Lee, Jeong Ik; Chang, Soon Heung; Jeong, Yong Hoon [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2015-10-15

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MW{sub th} and an electricity generation mode of 100 kW{sub th}, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and

Innovative concept for an ultra-small nuclear thermal rocket utilizing a new moderated reactor

International Nuclear Information System (INIS)

Nam, Seung Hyun; Venneri, Paolo; Kim, Yong Hee; Lee, Jeong Ik; Chang, Soon Heung; Jeong, Yong Hoon

2015-01-01

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MW th and an electricity generation mode of 100 kW th , equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics

Innovative concept for an ultra-small nuclear thermal rocket utilizing a new moderated reactor

Directory of Open Access Journals (Sweden)

Seung Hyun Nam

2015-10-01

Full Text Available Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER, for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MWth and an electricity generation mode of 100 kWth, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and

Deformation behavior of multilayered NiFe with bimodal grain size distribution at room and elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Fiebig, Jochen, E-mail: jmfiebig@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States); Jian, Jie [Department of Electrical and Computer Engineering, Texas A& M University, College Station, TX 77843-3128 (United States); Kurmanaeva, Lilia [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States); McCrea, Jon [Integran Technologies Inc., Toronto (Canada); Wang, Haiyan [Department of Electrical and Computer Engineering, Texas A& M University, College Station, TX 77843-3128 (United States); Lavernia, Enrique [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697 (United States); Mukherjee, Amiya [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States)

2016-02-22

We describe a study of the temperature dependent deformation behavior of a multilayered NiFe-60 wt%Fe alloy with a layer thickness of 5 μm fabricated by electrodeposition. The structure of adjacent layers alternates between a nanocrystalline and a coarse grained. Uniaxial tensile tests at temperature between 20 °C and 400 °C and strain rate of 10{sup −4}–10{sup −2} were used to determine the mechanical behavior. Microstructure observations via transmission electron microscopy and fractography were performed to provide insight into the underlying deformation mechanism. The mechanical behavior is discussed in the context of the bimodal microstructure of multilayered samples and the contribution of each sub-layer to strength and ductility. The results reveal that even at higher temperatures the nanocrystalline layer determines the mechanical performance of multilayered materials.

Data Mining of Chemogenomics Data Using Bi-Modal PLS Methods and Chemical Interpretation for Molecular Design.

Science.gov (United States)

Hasegawa, Kiyoshi; Funatsu, Kimito

2014-12-01

Chemogenomics is a new strategy in drug discovery for interrogating all molecules capable of interacting with all biological targets. Because of the almost infinite number of drug-like organic molecules, bench-based experimental chemogenomics methods are not generally feasible. Several in silico chemogenomics models have therefore been developed for high-throughput screening of large numbers of drug candidate compounds and target proteins. In previous studies, we described two novel bi-modal PLS approaches. These methods provide a significant advantage in that they enable direct connections to be made between biological activities and ligand and protein descriptors. In this special issue, we review these two PLS-based approaches using two different chemogenomics datasets for illustration. We then compare the predictive and interpretive performance of the two methods using the same congeneric data set. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced Athermal Telescopes, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This proposed innovative athermal telescope design uses advanced lightweight and high-stiffness material of Beryllium-Aluminum (Be-38Al). Peregrine's expertise with...

Advanced Control Engineering

DEFF Research Database (Denmark)

Zhou, Jianjun

1999-01-01

This book is developed as a textbook for the course Advanced Control Engineering. The book is intended for students in mechanical engineering and its aim is to provide an understanding of modern control theory as well as methodologies and applications for state space modeling and design...

Advanced fenestration and daylighting systems

Energy Technology Data Exchange (ETDEWEB)

McCluney, R. [Florida Solar Energy Centere, Cocoa, FL (United States)

1998-09-01

Advanced fenestration systems are new high-performance glazing and reflecting systems for otherwise conventional windows which offer specialized spectral and /or angular selectivity to provide improved illumination quantity and quality under optimal human comfort and energy conservation conditions. Advanced daylighting systems include systems manufactured by the solar lighting industry to introduce daylight into the core spaces of multi-storey buildings, spaces distant from the building envelope, or other locations where more conventional daylighting apertures cannot be placed. Details of operating, energy and illumination performance characteristics of both these systems were provided. It was concluded that solar lighting systems can effectively provide daylight illumination to interior spaces of a building that are not amenable to more conventional systems. Nevertheless, techniques need to be developed to predict the performance of such systems prior to their being built, so as to provide designers better means for justifying their use and economic viability, and to develop codes and performance standards to protect the consumer in the marketplace. 20 refs., 12 figs.

An advanced complex analysis problem book topological vector spaces, functional analysis, and Hilbert spaces of analytic functions

CERN Document Server

Alpay, Daniel

2015-01-01

This is an exercises book at the beginning graduate level, whose aim is to illustrate some of the connections between functional analysis and the theory of functions of one variable. A key role is played by the notions of positive definite kernel and of reproducing kernel Hilbert space. A number of facts from functional analysis and topological vector spaces are surveyed. Then, various Hilbert spaces of analytic functions are studied.

Space exploration and colonization - Towards a space faring society

Science.gov (United States)

Hammond, Walter E.

1990-01-01

Development trends of space exploration and colonization since 1957 are reviewed, and a five-phase evolutionary program planned for the long-term future is described. The International Geosphere-Biosphere program which is intended to provide the database on enviromental changes of the earth as a global system is considered. Evolution encompasses the anticipated advantages of such NASA observation projects as the Hubble Space Telescope, the Gamma Ray Observatory, the Advanced X-Ray Astrophysics Facility, and the Cosmic Background Explorer. Attention is given to requirements for space colonization, including development of artificial gravity and countermeasures to mitigate zero gravity problems; robotics and systems aimed to minimize human exposure to the space environment; the use of nuclear propulsion; and international collaboration on lunar-Mars projects. It is recommended that nuclear energy sources be developed for both propulsion and as extraterrestrial power plants.

Programmable Ultra Lightweight System Adaptable Radio (PULSAR) Low Cost Telemetry - Access from Space Advanced Technologies or Down the Middle

Science.gov (United States)

Sims. Herb; Varnavas, Kosta; Eberly, Eric

2013-01-01

Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 1990's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast, presently qualified satellite transponder applications were developed during the early 1960's space program. Programmable Ultra Lightweight System Adaptable Radio (PULSAR, NASA-MSFC SDR) technology revolutionizes satellite transponder technology by increasing data through-put capability by, at least, an order of magnitude. PULSAR leverages existing Marshall Space Flight Center SDR designs and commercially enhanced capabilities to provide a path to a radiation tolerant SDR transponder. These innovations will (1) reduce the cost of NASA Low Earth Orbit (LEO) and Deep Space transponders, (2) decrease power requirements, and (3) a commensurate volume reduction. Also, PULSAR increases flexibility to implement multiple transponder types by utilizing the same hardware with altered logic - no analog hardware change is required - all of which can be accomplished in orbit. This provides high capability, low cost, transponders to programs of all sizes. The final project outcome would be the introduction of a Technology Readiness Level (TRL) 7 low-cost CubeSat to SmallSat telemetry system into the NASA Portfolio.

Bimodal pollination system of the bromeliad Aechmea nudicaulis involving hummingbirds and bees.

Science.gov (United States)

Schmid, S; Schmid, V S; Zillikens, A; Harter-Marques, B; Steiner, J

2011-01-01

In order to compare the effectiveness of birds and insects as pollinators, we studied the floral biology of the bromeliad Aechmea nudicaulis (L.) Grisebach in the biome of the Atlantic rain forest, southern Brazil. On Santa Catarina Island, flowering extends from mid-September to the end of December, with diurnal anthesis. The reproductive system is obligatory xenogamy, thus pollinator-dependent. Flowers secrete 31.84 μl of nectar per day, with a mean sugar concentration of 23.2%. Highest nectar volume and sugar concentration occur at the beginning of anthesis. Most floral traits are characteristic for ornithophily, and nectar production appears to be adapted to the energy demand of hummingbirds. Continued secretion of the sucrose-dominated nectar attracts and binds visitors to inflorescences, strengthening trapline foraging behaviour. Experiments assessing seed set after single flower visits were performed with the most frequent visitors, revealing the hummingbird Thalurania glaucopis as the most effective pollen vector. In addition, bees are also functional pollinators, as substantiated by their high visitation frequency. We conclude that this pollination system is bimodal. Thus, there is redundancy in the pollination service provided by birds and bees, granting a high probability of successful reproduction in Ae. nudicaulis. © 2010 German Botanical Society and The Royal Botanical Society of the Netherlands.

Tsirelson's space

CERN Document Server

Casazza, Peter G

1989-01-01

This monograph provides a structure theory for the increasingly important Banach space discovered by B.S. Tsirelson. The basic construction should be accessible to graduate students of functional analysis with a knowledge of the theory of Schauder bases, while topics of a more advanced nature are presented for the specialist. Bounded linear operators are studied through the use of finite-dimensional decompositions, and complemented subspaces are studied at length. A myriad of variant constructions are presented and explored, while open questions are broached in almost every chapter. Two appendices are attached: one dealing with a computer program which computes norms of finitely-supported vectors, while the other surveys recent work on weak Hilbert spaces (where a Tsirelson-type space provides an example).

Bimodal bilingualism as multisensory training?: Evidence for improved audiovisual speech perception after sign language exposure.

Science.gov (United States)

Williams, Joshua T; Darcy, Isabelle; Newman, Sharlene D

2016-02-15

The aim of the present study was to characterize effects of learning a sign language on the processing of a spoken language. Specifically, audiovisual phoneme comprehension was assessed before and after 13 weeks of sign language exposure. L2 ASL learners performed this task in the fMRI scanner. Results indicated that L2 American Sign Language (ASL) learners' behavioral classification of the speech sounds improved with time compared to hearing nonsigners. Results indicated increased activation in the supramarginal gyrus (SMG) after sign language exposure, which suggests concomitant increased phonological processing of speech. A multiple regression analysis indicated that learner's rating on co-sign speech use and lipreading ability was correlated with SMG activation. This pattern of results indicates that the increased use of mouthing and possibly lipreading during sign language acquisition may concurrently improve audiovisual speech processing in budding hearing bimodal bilinguals. Copyright © 2015 Elsevier B.V. All rights reserved.

Intracellular bimodal nanoparticles based on quantum dots for high-field MRI at 21.1 T.

Science.gov (United States)

Rosenberg, Jens T; Kogot, Joshua M; Lovingood, Derek D; Strouse, Geoffrey F; Grant, Samuel C

2010-09-01

Multimodal, biocompatible contrast agents for high magnetic field applications represent a new class of nanomaterials with significant potential for tracking of fluorescence and MR in vitro and vivo. Optimized for high-field MR applications-including biomedical imaging at 21.1 T, the highest magnetic field available for MRI-these nanoparticles capitalize on the improved performance of chelated Dy(3+) with increasing magnetic field coupled to a noncytotoxic Indium Phosphide/Zinc Sulfide (InP/ZnS) quantum dot that provides fluorescence detection, MR responsiveness, and payload delivery. By surface modifying the quantum dot with a cell-penetrating peptide sequence coupled to an MR contrast agent, the bimodal nanomaterial functions as a self-transfecting high-field MR/optical contrast agent for nonspecific intracellular labeling. Fluorescent images confirm sequestration in perinuclear vesicles of labeled cells, with no apparent cytotoxicity. These techniques can be extended to impart cell selectivity or act as a delivery vehicle for genetic or pharmaceutical interventions. 2010 Wiley-Liss, Inc.

Mesoporous ethanesilica materials with bimodal and trimodal pore-size distributions synthesised in the presence of cobalt ions

Directory of Open Access Journals (Sweden)

Alufelwi M. Tshavhungwe

2010-07-01

Full Text Available Mesoporous organosilica materials containing ethane groups in their framework were formed with two and three pore sizes (i.e. bimodal and trimodal pores when synthesised by the sol-gel method in the presence of cobalt ions. The compounds 1,2-bistrimethoxysilylethane and tetraethylorthosilicate were used as silicon sources and the reactions were done in the presence of a surfactant, which served as a template. Diffuse reflectance infrared Fourier transform spectroscopy revealed that organic functional groups were incorporated into the ethanesilica. Powder X-ray diffraction and nitrogen adsorption data indicated that the mesophase and textural properties (surface area, pore volume, pore diameter of the materials were dependent on the ageing temperature, the amount/ratio of silica precursors and cobalt ion incorporation. Secondary mesopores were drastically reduced by changing the ratio of silicon precursors.

The Future of Astrometry in Space

Directory of Open Access Journals (Sweden)

Antonella Vallenari

2018-04-01

Full Text Available This contribution focuses on the importance of astrometry and on its future developments. Over the centuries astrometry has greatly contributed to the advance of the knowledge of the Universe. Nowadays a major breakthrough is on the way due to astrometric sky surveys from space. ESA space missions Hipparcos first and then Gaia point out the outstanding contribution that space astrometry can provide to our knowledge in many fields of astrophysics, going from the Milky Way formation and evolution, to stellar astrophysics, extra-galactic astrophysics, and fundamental physics. We briefly outline the properties of Gaia first and second data release, and the accuracies expected end-of-mission. The next big advance in space astrometry would be either to improve the astrometric accuracy of one order of magnitude, or to move to a different wavelength domain. While both options have the potential to bring us in a new era of discovery, they have to face enormous issues. We summarize the future directions in space astrometry that are proposed or under investigation by the scientific community, their main challenges and the expected outcome.

Strong bimodality in the host halo mass of central galaxies from galaxy-galaxy lensing

Science.gov (United States)

Mandelbaum, Rachel; Wang, Wenting; Zu, Ying; White, Simon; Henriques, Bruno; More, Surhud

2016-04-01

We use galaxy-galaxy lensing to study the dark matter haloes surrounding a sample of locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey. We measure mean halo mass as a function of the stellar mass and colour of the central galaxy. Mock catalogues constructed from semi-analytic galaxy formation simulations demonstrate that most LBGs are the central objects of their haloes, greatly reducing interpretation uncertainties due to satellite contributions to the lensing signal. Over the full stellar mass range, 10.3 10.7. Tests using the mock catalogues and on the data themselves clarify the effects of LBG selection and show that it cannot artificially induce a systematic dependence of halo mass on LBG colour. The bimodality in halo mass at fixed stellar mass is reproduced by the astrophysical model underlying our mock catalogue, but the sign of the effect is inconsistent with recent, nearly parameter-free age-matching models. The sign and magnitude of the effect can, however, be reproduced by halo occupation distribution models with a simple (few-parameter) prescription for type dependence.

Harmonic analysis on reductive symmetric spaces

NARCIS (Netherlands)

Ban, E.P. van den; Schlichtkrull, H.

2000-01-01

We give a relatively non-technical survey of some recent advances in the Fourier theory for semisimple symmetric spaces. There are three major results: An inversion formula for the Fourier transform, a Palley-Wiener theorem, which describes the Fourier image of the space of completely supported

Superconducting magnets advanced in particle physics

International Nuclear Information System (INIS)

Yamamoto, Akira

2000-01-01

Superconducting magnet technology for particle detectors has been advanced to provide large-scale magnetic fields in particle physics experiments. The technology has been progressed to meet physics goals and the detector requirement of having maximum magnetic field with minimum material and space. This paper includes an overview of the advances of particle detector magnets and discusses key technologies

Solar wind structure suggested by bimodal correlations of solar wind speed and density between the spacecraft SOHO and Wind

Science.gov (United States)

Ogilvie, K. W.; Coplan, M. A.; Roberts, D. A.; Ipavich, F.

2007-08-01

We calculate the cross-spacecraft maximum lagged-cross-correlation coefficients for 2-hour intervals of solar wind speed and density measurements made by the plasma instruments on the Solar and Heliospheric Observatory (SOHO) and Wind spacecraft over the period from 1996, the minimum of solar cycle 23, through the end of 2005. During this period, SOHO was located at L1, about 200 R E upstream from the Earth, while Wind spent most of the time in the interplanetary medium at distances of more than 100 R E from the Earth. Yearly histograms of the maximum, time-lagged correlation coefficients for both the speed and density are bimodal in shape, suggesting the existence of two distinct solar wind regimes. The larger correlation coefficients we suggest are due to structured solar wind, including discontinuities and shocks, while the smaller are likely due to Alfvénic turbulence. While further work will be required to firmly establish the physical nature of the two populations, the results of the analysis are consistent with a solar wind that consists of turbulence from quiet regions of the Sun interspersed with highly filamentary structures largely convected from regions in the inner solar corona. The bimodal appearance of the distributions is less evident in the solar wind speed than in the density correlations, consistent with the observation that the filamentary structures are convected with nearly constant speed by the time they reach 1 AU. We also find that at solar minimum the fits for the density correlations have smaller high-correlation components than at solar maximum. We interpret this as due to the presence of more relatively uniform Alfvénic regions at solar minimum than at solar maximum.

Low-photon-number optical switch and AND/OR logic gates based on quantum dot-bimodal cavity coupling system.

Science.gov (United States)

Ma, Shen; Ye, Han; Yu, Zhong-Yuan; Zhang, Wen; Peng, Yi-Wei; Cheng, Xiang; Liu, Yu-Min

2016-01-11

We propose a new scheme based on quantum dot-bimodal cavity coupling system to realize all-optical switch and logic gates in low-photon-number regime. Suppression of mode transmission due to the destructive interference effect is theoretically demonstrated by driving the cavity with two orthogonally polarized pulsed lasers at certain pulse delay. The transmitted mode can be selected by designing laser pulse sequence. The optical switch with high on-off ratio emerges when considering one driving laser as the control. Moreover, the AND/OR logic gates based on photon polarization are achieved by cascading the coupling system. Both proposed optical switch and logic gates work well in ultra-low energy magnitude. Our work may enable various applications of all-optical computing and quantum information processing.

Carbon composites in space vehicle structures

Science.gov (United States)

Mayer, N. J.

1974-01-01

Recent developments in the technology of carbon or graphite filaments now provide the designer with greatly improved materials offering high specific strength and modulus. Besides these advantages are properties which are distinctly useful for space applications and which provide feasibility for missions not obtainable by other means. Current applications include major and secondary structures of communications satellites. A number of R & D projects are exploring carbon-fiber application to rocket engine motor cases, advanced antenna systems, and space shuttle components. Future system studies are being made, based on the successful application of carbon fibers for orbiting space telescope assemblies, orbital transfer vehicles, and very large deployable energy generation systems. Continued technology development is needed in analysis, material standards, and advanced structural concepts to exploit the full potential of carbon filaments in composite materials.

SpacePy - a Python-based library of tools for the space sciences

International Nuclear Information System (INIS)

Morley, Steven K.; Welling, Daniel T.; Koller, Josef; Larsen, Brian A.; Henderson, Michael G.

2010-01-01

Space science deals with the bodies within the solar system and the interplanetary medium; the primary focus is on atmospheres and above - at Earth the short timescale variation in the the geomagnetic field, the Van Allen radiation belts and the deposition of energy into the upper atmosphere are key areas of investigation. SpacePy is a package for Python, targeted at the space sciences, that aims to make basic data analysis, modeling and visualization easier. It builds on the capabilities of the well-known NumPy and MatPlotLib packages. Publication quality output direct from analyses is emphasized. The SpacePy project seeks to promote accurate and open research standards by providing an open environment for code development. In the space physics community there has long been a significant reliance on proprietary languages that restrict free transfer of data and reproducibility of results. By providing a comprehensive, open-source library of widely used analysis and visualization tools in a free, modern and intuitive language, we hope that this reliance will be diminished. SpacePy includes implementations of widely used empirical models, statistical techniques used frequently in space science (e.g. superposed epoch analysis), and interfaces to advanced tools such as electron drift shell calculations for radiation belt studies. SpacePy also provides analysis and visualization tools for components of the Space Weather Modeling Framework - currently this only includes the BATS-R-US 3-D magnetohydrodynamic model and the RAM ring current model - including streamline tracing in vector fields. Further development is currently underway. External libraries, which include well-known magnetic field models, high-precision time conversions and coordinate transformations are wrapped for access from Python using SWIG and f2py. The rest of the tools have been implemented directly in Python. The provision of open-source tools to perform common tasks will provide openness in the

Advances in satellite communications

CERN Document Server

Minoli, Daniel

2015-01-01

Discussing advances in modulation techniques and HTS spotbeam technologiesSurveying emerging high speed aeronautical mobility services and maritime and other terrestrial mobility servicesAssessing M2M (machine-to-machine) applications, emerging Ultra HD video technologies and new space technology

Diverse Kir expression contributes to distinct bimodal distribution of resting potentials and vasotone responses of arterioles.

Directory of Open Access Journals (Sweden)

Yuqin Yang

Full Text Available The resting membrane potential (RP of vascular smooth muscle cells (VSMCs is a major determinant of cytosolic calcium concentration and vascular tone. The heterogeneity of RPs and its underlying mechanism among different vascular beds remain poorly understood. We compared the RPs and vasomotion properties between the guinea pig spiral modiolar artery (SMA, brain arterioles (BA and mesenteric arteries (MA. We found: 1 RPs showed a robust bimodal distribution peaked at -76 and -40 mV evenly in the SMA, unevenly at -77 and -51 mV in the BA and ~-71 and -52 mV in the MA. Ba(2+ 0.1 mM eliminated their high RP peaks ~-75 mV. 2 Cells with low RP (~-45 mV hyperpolarized in response to 10 mM extracellular K(+, while cells with a high RP depolarized, and cells with intermediate RP (~-58 mV displayed an initial hyperpolarization followed by prolonged depolarization. Moderate high K(+ typically induced dilation, constriction and a dilation followed by constriction in the SMA, MA and BA, respectively. 3 Boltzmann-fit analysis of the Ba(2+-sensitive inward rectifier K(+ (Kir whole-cell current showed that the maximum Kir conductance density significantly differed among the vessels, and the half-activation voltage was significantly more negative in the MA. 4 Corresponding to the whole-cell data, computational modeling simulated the three RP distribution patterns and the dynamics of RP changes obtained experimentally, including the regenerative swift shifts between the two RP levels after reaching a threshold. 5 Molecular works revealed strong Kir2.1 and Kir2.2 transcripts and Kir2.1 immunolabeling in all 3 vessels, while Kir2.3 and Kir2.4 transcript levels varied. We conclude that a dense expression of functional Kir2.X channels underlies the more negative RPs in endothelial cells and a subset of VSMC in these arterioles, and the heterogeneous Kir function is primarily responsible for the distinct bimodal RPs among these arterioles. The fast Kir

Update on Risk Reduction Activities for a Liquid Advanced Booster for NASA's Space Launch System

Science.gov (United States)

Crocker, Andrew M.; Greene, William D.

2017-01-01

The stated goals of NASA's Research Announcement for the Space Launch System (SLS) Advanced Booster Engineering Demonstration and/or Risk Reduction (ABEDRR) are to reduce risks leading to an affordable Advanced Booster that meets the evolved capabilities of SLS and enable competition by mitigating targeted Advanced Booster risks to enhance SLS affordability. Dynetics, Inc. and Aerojet Rocketdyne (AR) formed a team to offer a wide-ranging set of risk reduction activities and full-scale, system-level demonstrations that support NASA's ABEDRR goals. During the ABEDRR effort, the Dynetics Team has modified flight-proven Apollo-Saturn F-1 engine components and subsystems to improve affordability and reliability (e.g., reduce parts counts, touch labor, or use lower cost manufacturing processes and materials). The team has built hardware to validate production costs and completed tests to demonstrate it can meet performance requirements. State-of-the-art manufacturing and processing techniques have been applied to the heritage F-1, resulting in a low recurring cost engine while retaining the benefits of Apollo-era experience. NASA test facilities have been used to perform low-cost risk-reduction engine testing. In early 2014, NASA and the Dynetics Team agreed to move additional large liquid oxygen/kerosene engine work under Dynetics' ABEDRR contract. Also led by AR, the objectives of this work are to demonstrate combustion stability and measure performance of a 500,000 lbf class Oxidizer-Rich Staged Combustion (ORSC) cycle main injector. A trade study was completed to investigate the feasibility, cost effectiveness, and technical maturity of a domestically-produced engine that could potentially both replace the RD-180 on Atlas V and satisfy NASA SLS payload-to-orbit requirements via an advanced booster application. Engine physical dimensions and performance parameters resulting from this study provide the system level requirements for the ORSC risk reduction test article

Production of potato minitubers using advanced environmental control technologies developed for growing plants in space

Science.gov (United States)

Britt, Robert G.

1998-01-01

Development of plant growth systems for use in outer space have been modified for use on earth as the backbone of a new system for rapid growth of potato minitubers. The automation of this new biotechnology provides for a fully controllable method of producing pathogen-free nuclear stock potato minitubers from tissue cultured clones of varieties of potato in a biomanufacturing facility. These minitubers are the beginning stage of seed potato production. Because the new system provides for pathogen-free minitubers by the tens-of-millions, rather than by the thousands which are currently produced in advanced seed potato systems, a new-dimension in seed potato development, breeding and multiplication has been achieved. The net advantage to earth-borne agricultural farming systems will be the elimination of several years of seed multiplication from the current system, higher quality potato production, and access to new potato varieties resistant to diseases and insects which will eliminate the need for chemical controls.