The Sustainable Development of Space: Astro-environmental and dynamical considerations

NASA Astrophysics Data System (ADS)

Boley, Aaron; Byers, Michael; Russell, Sara

2018-04-01

The sustainable development of space is a global (and exo-global) challenge that is not limited by borders or research disciplines. Sustainable development is "development that meets the needs of the present without compromising the ability of future generations to meet their own needs". While the development of space brings new economic and scientific possibilities, it also carries significant political, legal, and technical uncertainties. For example, the rapidly increasing accessibility of space is motivating states to unilaterally adopt legislation for the new era of space use, which may have significant unintended consequences, such as increased risks to space assets, disputes among state as well as non-state actors, and changes to unique astro-environments. Any policy or legal position must be informed by the dynamical and astrophysical realities of space use, creating complex and interwoven challenges. Here, we explore several of these potential challenges related to astro-environmentalism, space minining operations, and the associated dynamics.

Questioning the Fidelity of the "Next Generation Science Standards" for Astronomy and Space Sciences Education

ERIC Educational Resources Information Center

Slater, Stephanie J.; Slater, Timothy F.

2015-01-01

Although the Next Generation Science Standards (NGSS) are not federally mandated national standards or performance expectations for K-12 schools in the United States, they stand poised to become a de facto national science and education policy, as state governments, publishers of curriculum materials, and assessment providers across the country…

System theory on group manifolds and coset spaces.

NASA Technical Reports Server (NTRS)

Brockett, R. W.

1972-01-01

The purpose of this paper is to study questions regarding controllability, observability, and realization theory for a particular class of systems for which the state space is a differentiable manifold which is simultaneously a group or, more generally, a coset space. We show that it is possible to give rather explicit expressions for the reachable set and the set of indistinguishable states in the case of autonomous systems. We also establish a type of state space isomorphism theorem. Our objective is to reduce all questions about the system to questions about Lie algebras generated from the coefficient matrices entering in the description of the system and in that way arrive at conditions which are easily visualized and tested.

Dynamics Sampling in Transition Pathway Space.

PubMed

Zhou, Hongyu; Tao, Peng

2018-01-09

The minimum energy pathway contains important information describing the transition between two states on a potential energy surface (PES). Chain-of-states methods were developed to efficiently calculate minimum energy pathways connecting two stable states. In the chain-of-states framework, a series of structures are generated and optimized to represent the minimum energy pathway connecting two states. However, multiple pathways may exist connecting two existing states and should be identified to obtain a full view of the transitions. Therefore, we developed an enhanced sampling method, named as the direct pathway dynamics sampling (DPDS) method, to facilitate exploration of a PES for multiple pathways connecting two stable states as well as addition minima and their associated transition pathways. In the DPDS method, molecular dynamics simulations are carried out on the targeting PES within a chain-of-states framework to directly sample the transition pathway space. The simulations of DPDS could be regulated by two parameters controlling distance among states along the pathway and smoothness of the pathway. One advantage of the chain-of-states framework is that no specific reaction coordinates are necessary to generate the reaction pathway, because such information is implicitly represented by the structures along the pathway. The chain-of-states setup in a DPDS method greatly enhances the sufficient sampling in high-energy space between two end states, such as transition states. By removing the constraint on the end states of the pathway, DPDS will also sample pathways connecting minima on a PES in addition to the end points of the starting pathway. This feature makes DPDS an ideal method to directly explore transition pathway space. Three examples demonstrate the efficiency of DPDS methods in sampling the high-energy area important for reactions on the PES.

A bulk localized state and new holographic renormalization group flow in 3D spin-3 gravity

NASA Astrophysics Data System (ADS)

Nakayama, Ryuichi; Suzuki, Tomotaka

2018-04-01

We construct a localized state of a scalar field in 3D spin-3 gravity. 3D spin-3 gravity is thought to be holographically dual to W3-extended CFT on a boundary at infinity. It is known that while W3 algebra is a nonlinear algebra, in the limit of large central charge c a linear finite-dimensional subalgebra generated by Wn (n = 0,±1,±2) and Ln (n = 0,±1) is singled out. The localized state is constructed in terms of these generators. To write down an equation of motion for a scalar field which is satisfied by this localized state, it is necessary to introduce new variables for an internal space α±, β±, γ, in addition to ordinary coordinates x± and y. The higher-dimensional space, which combines the bulk space-time with the “internal space,” which is an analog of superspace in supersymmetric theory, is introduced. The “physical bulk space-time” is a 3D hypersurface with constant α±, β± and γ embedded in this space. We will work in Poincaré coordinates of AdS space and consider W-quasi-primary operators Φh(x+) with a conformal weight h in the boundary and study two and three point functions of W-quasi-primary operators transformed as eix+L‑1heβ+W‑1hΦh(0)e‑β+W‑1he‑ix+L‑1h. Here, Lnh and Wnh are sl(3,R) generators in the hyperbolic basis for Poincaré coordinates. It is shown that in the β+ →∞ limit, the conformal weight changes to a new value h‧ = h/2. This may be regarded as a Renormalization Group (RG) flow. It is argued that this RG flow will be triggered by terms ΔS ∝ β+W ‑1h + β‑W¯ ‑1h added to the action.

Stochastic state-space temperature regulation of biochar production. Part I: Theoretical development.

PubMed

Cantrell, Keri B; Martin, Jerry H

2012-02-01

The concept of a designer biochar that targets the improvement of a specific soil property imposes the need for production processes to generate biochars with both high consistency and quality. These important production parameters can be affected by variations in process temperature that must be taken into account when controlling the pyrolysis of agricultural residues such as manures and other feedstocks. A novel stochastic state-space temperature regulator was developed to accurately match biochar batch production to a defined temperature input schedule. This was accomplished by describing the system's state-space with five temperature variables--four directly measured and one change in temperature. Relationships were derived between the observed state and the desired, controlled state. When testing the unit at two different temperatures, the actual pyrolytic temperature was within 3 °C of the control with no overshoot. This state-space regulator simultaneously controlled the indirect heat source and sample temperature by employing difficult-to-measure variables such as temperature stability in the description of the pyrolysis system's state-space. These attributes make a state-space controller an optimum control scheme for the production of a predictable, repeatable designer biochar. Published 2011 by John Wiley & Sons, Ltd.

Nuclear Power in Space

DOE R&D Accomplishments Database

1994-01-01

In the early years of the United States space program, lightweight batteries, fuel cells, and solar modules provided electric power for space missions. As missions became more ambitious and complex, power needs increased and scientists investigated various options to meet these challenging power requirements. One of the options was nuclear energy. By the mid-1950s, research had begun in earnest on ways to use nuclear power in space. These efforts resulted in the first radioisotope thermoelectric generators (RTGs), which are nuclear power generators build specifically for space and special terrestrial uses. These RTGs convert the heat generated from the natural decay of their radioactive fuel into electricity. RTGs have powered many spacecraft used for exploring the outer planets of the solar system and orbiting the sun and Earth. They have also landed on Mars and the moon. They provide the power that enables us to see and learn about even the farthermost objects in our solar system.

Spacecraft Power Systems Engineering: Solutions for NASA's Manned Space Program

NASA Technical Reports Server (NTRS)

Scott, John H.

2007-01-01

An overview of spacecraft power systems is presented, with a focus on applications in the manned space program. The topics include: 1) History; 2) State-of-the-art; 3) Development directions; 4) Focus on applications in the manned space program led from JSC; 5) Power Systems Engineering Trade Space; 6) Power Generation and Energy Storage; 7) Power Distribution and Control; and 8) Actuation

Crossing the dividing surface of transition state theory. III. Once and only once. Selecting reactive trajectories

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

Lorquet, J. C., E-mail: jc.lorquet@ulg.ac.be

2015-09-14

The purpose of the present work is to determine initial conditions that generate reacting, recrossing-free trajectories that cross the conventional dividing surface of transition state theory (i.e., the plane in configuration space passing through a saddle point of the potential energy surface and perpendicular to the reaction coordinate) without ever returning to it. Local analytical equations of motion valid in the neighborhood of this planar surface have been derived as an expansion in Poisson brackets. We show that the mere presence of a saddle point implies that reactivity criteria can be quite simply formulated in terms of elements of thismore » series, irrespective of the shape of the potential energy function. Some of these elements are demonstrated to be equal to a sum of squares and thus to be necessarily positive, which has a profound impact on the dynamics. The method is then applied to a three-dimensional model describing an atom-diatom interaction. A particular relation between initial conditions is shown to generate a bundle of reactive trajectories that form reactive cylinders (or conduits) in phase space. This relation considerably reduces the phase space volume of initial conditions that generate recrossing-free trajectories. Loci in phase space of reactive initial conditions are presented. Reactivity is influenced by symmetry, as shown by a comparative study of collinear and bent transition states. Finally, it is argued that the rules that have been derived to generate reactive trajectories in classical mechanics are also useful to build up a reactive wave packet.« less

The Next Generation Science Standards: A potential revolution for geoscience education

NASA Astrophysics Data System (ADS)

Wysession, Michael E.

2014-05-01

The first and only set of U.S.-nationally distributed K-12 science education standards have been adopted by many states across America, with the potential to be adopted by many more. Earth and space science plays a prominent role in the new standards, with particular emphasis on critical Earth issues such as climate change, sustainability, and human impacts on Earth systems. In the states that choose to adopt the Next Generation Science Standards (NGSS), American youth will have a rigorous practice-based formal education in these important areas. Much work needs to be done to insure the adoption and adequate implementation of the NGSS by a majority of American states, however, and there are many things that Earth and space scientists can do to help facilitate the process.

Molecular Dynamics of Flexible Polar Cations in a Variable Confined Space: Toward Exceptional Two-Step Nonlinear Optical Switches.

PubMed

Xu, Wei-Jian; He, Chun-Ting; Ji, Cheng-Min; Chen, Shao-Li; Huang, Rui-Kang; Lin, Rui-Biao; Xue, Wei; Luo, Jun-Hua; Zhang, Wei-Xiong; Chen, Xiao-Ming

2016-07-01

The changeable molecular dynamics of flexible polar cations in the variable confined space between inorganic chains brings about a new type of two-step nonlinear optical (NLO) switch with genuine "off-on-off" second harmonic generation (SHG) conversion between one NLO-active state and two NLO-inactive states. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lidar-based estimates of aboveground biomass in the continental US and Mexico using ground, airborne, and satellite observations

Treesearch

Ross Nelson; Hank Margolis; Paul Montesano; Guoqing Sun; Bruce Cook; Larry Corp; Hans-Erik Andersen; Ben deJong; Fernando Paz Pellat; Thaddeus Fickel; Jobriath Kauffman; Stephen Prisley

2017-01-01

Existing national forest inventory plots, an airborne lidar scanning (ALS) system, and a space profiling lidar system (ICESat-GLAS) are used to generate circa 2005 estimates of total aboveground dry biomass (AGB) in forest strata, by state, in the continental United States (CONUS) and Mexico. The airborne lidar is used to link ground observations of AGB to space lidar...

Space Biology in the 21st century

NASA Technical Reports Server (NTRS)

Halstead, Thora W.; Krauss, Robert W.

1990-01-01

Space Biology is poised to make significant contributions to science in the next century. A carefully crafted, but largely ground-based, program in the United States has evolved major questions that require answers through experiments in space. Science, scientists, and the new long-term spacecrafts designed by NASA will be available for the first time to mount a serious Space Biology effort. The scientific challenge is of such importance that success will provide countless benefits to biologically dependent areas such as medicine, food, and commerce in the decades ahead. The international community is rapidly expanding its role in this field. The United States should generate the resources that will allow progress in Space Biology to match the recognized progress made in aeronautics and the other space sciences.

Alternative strategies for space station financing

NASA Technical Reports Server (NTRS)

Walklet, D. C.; Heenan, A. T.

1983-01-01

The attributes of the proposed space station program are oriented toward research activities and technologies which generate long term benefits for mankind. Unless such technologies are deemed of national interest and thus are government funded, they must stand on their own in the market place. Therefore, the objectives of a United States space station should be based on commercial criteria; otherwise, such a project attracts no long term funding. There is encouraging evidence that some potential space station activities should generate revenues from shuttle related projects within the decade. Materials processing concepts as well as remote sensing indicate substantial potential. Futhermore, the economics and thus the commercial feasibility of such projects will be improved by the operating efficiencies available with an ongoing space station program.

On the importance of an accurate representation of the initial state of the system in classical dynamics simulations

NASA Astrophysics Data System (ADS)

García-Vela, A.

2000-05-01

A definition of a quantum-type phase-space distribution is proposed in order to represent the initial state of the system in a classical dynamics simulation. The central idea is to define an initial quantum phase-space state of the system as the direct product of the coordinate and momentum representations of the quantum initial state. The phase-space distribution is then obtained as the square modulus of this phase-space state. The resulting phase-space distribution closely resembles the quantum nature of the system initial state. The initial conditions are sampled with the distribution, using a grid technique in phase space. With this type of sampling the distribution of initial conditions reproduces more faithfully the shape of the original phase-space distribution. The method is applied to generate initial conditions describing the three-dimensional state of the Ar-HCl cluster prepared by ultraviolet excitation. The photodissociation dynamics is simulated by classical trajectories, and the results are compared with those of a wave packet calculation. The classical and quantum descriptions are found in good agreement for those dynamical events less subject to quantum effects. The classical result fails to reproduce the quantum mechanical one for the more strongly quantum features of the dynamics. The properties and applicability of the phase-space distribution and the sampling technique proposed are discussed.

Legal Consequences of the Pollution of Outer Space with Space Debris

NASA Astrophysics Data System (ADS)

Stubbe, Peter

2017-07-01

Space debris has grown to be a significant problem for outer space activities. The remnants of human activities in space are very diverse; they can be tiny paint flakes, all sorts of fragments, or entirely intact—but otherwise nonfunctional spacecraft and rocket bodies. The amount of debris is increasing at a growing pace, thus raising the risk of collision with operational satellites. Due to the relative high velocities involved in on-orbit collisions, their consequences are severe; collisions lead to significant damage or the complete destruction of the affected spacecraft. Protective measures and collision avoidance have thus become a major concern for spacecraft operators. The pollution of space with debris must, however, not only be seen as an unfavorable circumstance that accompanies space activities and increases the costs and complexity of outer space activities. Beyond this rather technical perspective, the presence of man-made, nonfunctional objects in space represents a global environmental concern. Similar to the patterns of other environmental problems on Earth, debris generation appears to have surpassed the absorption capacity of the space environment. Studies indicate that the evolution of the space object environment has crossed the tipping point to a runaway situation in which an increasing number of collisions―mostly among debris―leads to an uncontrolled population growth. It is thus in the interest of all mankind to address the debris problem in order to preserve the space environment for future generations. International space law protects the space environment. Article IX of the Outer Space Treaty obligates States to avoid the harmful contamination of outer space. The provision corresponds to the obligation to protect the environment in areas beyond national jurisdiction under the customary "no harm" rule of general environmental law. These norms are applicable to space debris and establish the duty not to pollute outer space by limiting the generation of debris. They become all the more effective when the principles of sustainable development are taken into account, which infuse considerations of intra- as well as inter-generational justice into international law. In view of the growing debris pollution and its related detrimental effects, it is obvious that questions of liability and responsibility will become increasingly relevant. The Liability Convention offers a remedy for victims having suffered damage caused by space debris. The launching State liability that it establishes is even absolute for damage occurring on the surface of the Earth. The secondary rules of international responsibility law go beyond mere compensation: States can also be held accountable for the environmental pollution event itself, entailing a number of consequential obligations, among them―under certain circumstances―a duty to active debris removal. While international law is, therefore, generally effective in addressing the debris problem, growing use and growing risks necessitate the establishment of a comprehensive traffic management regime for outer space. It would strengthen the rule of law in outer space and ensure the sustainability of space utilization.

Investigation of a catalytic gas generator for the Space Shuttle APU. [hydrazine Auxiliary Propulsion Unit

NASA Technical Reports Server (NTRS)

Emmons, D. L.; Huxtable, D. D.; Blevins, D. R.

1974-01-01

An investigation was conducted to establish the capability of a monopropellant hydrazine catalytic gas generator to meet the requirements specified for the Space Shuttle APU. Detailed analytical and experimental studies were conducted on potential problem areas including long-term nitriding effects on materials, design variables affecting catalyst life, vehicle vibration effects, and catalyst oxidation/contamination. A full-scale gas generator, designed to operate at a chamber pressure of 750 psia and a flow rate of 0.36 lbm/sec, was fabricated and subjected to three separate life test series. The objective of the first test series was to demonstrate the capability of the gas generator to successfully complete 20 simulated Space Shuttle missions in steady-state operation. The gas generator was then refurbished and subjected to a second series of tests to demonstrate the pulse-mode capability of the gas generator during 20 simulated missions. The third series of tests was conducted with a refurbished reactor to further demonstrate pulse-mode capability with a modified catalyst bed.

Planning Assembly Of Large Truss Structures In Outer Space

NASA Technical Reports Server (NTRS)

De Mello, Luiz S. Homem; Desai, Rajiv S.

1992-01-01

Report dicusses developmental algorithm used in systematic planning of sequences of operations in which large truss structures assembled in outer space. Assembly sequence represented by directed graph called "assembly graph", in which each arc represents joining of two parts or subassemblies. Algorithm generates assembly graph, working backward from state of complete assembly to initial state, in which all parts disassembled. Working backward more efficient than working forward because it avoids intermediate dead ends.

Study of auxiliary propulsion requirements for large space systems, volume 2

NASA Technical Reports Server (NTRS)

Smith, W. W.; Machles, G. W.

1983-01-01

A range of single shuttle launched large space systems were identified and characterized including a NASTRAN and loading dynamics analysis. The disturbance environment, characterization of thrust level and APS mass requirements, and a study of APS/LSS interactions were analyzed. State-of-the-art capabilities for chemical and ion propulsion were compared with the generated propulsion requirements to assess the state-of-the-art limitations and benefits of enhancing current technology.

Entanglement Holographic Mapping of Many-Body Localized System by Spectrum Bifurcation Renormalization Group

NASA Astrophysics Data System (ADS)

You, Yi-Zhuang; Qi, Xiao-Liang; Xu, Cenke

We introduce the spectrum bifurcation renormalization group (SBRG) as a generalization of the real-space renormalization group for the many-body localized (MBL) system without truncating the Hilbert space. Starting from a disordered many-body Hamiltonian in the full MBL phase, the SBRG flows to the MBL fixed-point Hamiltonian, and generates the local conserved quantities and the matrix product state representations for all eigenstates. The method is applicable to both spin and fermion models with arbitrary interaction strength on any lattice in all dimensions, as long as the models are in the MBL phase. In particular, we focus on the 1 d interacting Majorana chain with strong disorder, and map out its phase diagram using the entanglement entropy. The SBRG flow also generates an entanglement holographic mapping, which duals the MBL state to a fragmented holographic space decorated with small blackholes.

Optimized decoy state QKD for underwater free space communication

NASA Astrophysics Data System (ADS)

Lopes, Minal; Sarwade, Nisha

Quantum cryptography (QC) is envisioned as a solution for global key distribution through fiber optic, free space and underwater optical communication due to its unconditional security. In view of this, this paper investigates underwater free space quantum key distribution (QKD) model for enhanced transmission distance, secret key rates and security. It is reported that secure underwater free space QKD is feasible in the clearest ocean water with the sifted key rates up to 207kbps. This paper extends this work by testing performance of optimized decoy state QKD protocol with underwater free space communication model. The attenuation of photons, quantum bit error rate and the sifted key generation rate of underwater quantum communication is obtained with vector radiative transfer theory and Monte Carlo method. It is observed from the simulations that optimized decoy state QKD evidently enhances the underwater secret key transmission distance as well as secret key rates.

NASA Propulsion Engineering Research Center, volume 2

NASA Technical Reports Server (NTRS)

1993-01-01

On 8-9 Sep. 1993, the Propulsion Engineering Research Center (PERC) at The Pennsylvania State University held its Fifth Annual Symposium. PERC was initiated in 1988 by a grant from the NASA Office of Aeronautics and Space Technology as a part of the University Space Engineering Research Center (USERC) program; the purpose of the USERC program is to replenish and enhance the capabilities of our Nation's engineering community to meet its future space technology needs. The Centers are designed to advance the state-of-the-art in key space-related engineering disciplines and to promote and support engineering education for the next generation of engineers for the national space program and related commercial space endeavors. Research on the following areas was initiated: liquid, solid, and hybrid chemical propulsion, nuclear propulsion, electrical propulsion, and advanced propulsion concepts.

Reduced order modeling of head related transfer functions for virtual acoustic displays

NASA Astrophysics Data System (ADS)

Willhite, Joel A.; Frampton, Kenneth D.; Grantham, D. Wesley

2003-04-01

The purpose of this work is to improve the computational efficiency in acoustic virtual applications by creating and testing reduced order models of the head related transfer functions used in localizing sound sources. State space models of varying order were generated from zero-elevation Head Related Impulse Responses (HRIRs) using Kungs Single Value Decomposition (SVD) technique. The inputs to the models are the desired azimuths of the virtual sound sources (from minus 90 deg to plus 90 deg, in 10 deg increments) and the outputs are the left and right ear impulse responses. Trials were conducted in an anechoic chamber in which subjects were exposed to real sounds that were emitted by individual speakers across a numbered speaker array, phantom sources generated from the original HRIRs, and phantom sound sources generated with the different reduced order state space models. The error in the perceived direction of the phantom sources generated from the reduced order models was compared to errors in localization using the original HRIRs.

Phase-space representations of symmetric informationally complete positive-operator-valued-measure fiducial states

NASA Astrophysics Data System (ADS)

Saraceno, Marcos; Ermann, Leonardo; Cormick, Cecilia

2017-03-01

The problem of finding symmetric informationally complete positive-operator-valued-measures (SIC-POVMs) has been solved numerically for all dimensions d up to 67 [A. J. Scott and M. Grassl, J. Math. Phys. 51, 042203 (2010), 10.1063/1.3374022], but a general proof of existence is still lacking. For each dimension, it was shown that it is possible to find a SIC-POVM that is generated from a fiducial state upon application of the operators of the Heisenberg-Weyl group. We draw on the numerically determined fiducial states to study their phase-space features, as displayed by the characteristic function and the Wigner, Bargmann, and Husimi representations, adapted to a Hilbert space of finite dimension. We analyze the phase-space localization of fiducial states, and observe that the SIC-POVM condition is equivalent to a maximal delocalization property. Finally, we explore the consequences in phase space of the conjectured Zauner symmetry. In particular, we construct a Hermitian operator commuting with this symmetry that leads to a representation of fiducial states in terms of eigenfunctions with definite semiclassical features.

A Quantitative Reliability, Maintainability and Supportability Approach for NASA's Second Generation Reusable Launch Vehicle

NASA Technical Reports Server (NTRS)

Safie, Fayssal M.; Daniel, Charles; Kalia, Prince; Smith, Charles A. (Technical Monitor)

2002-01-01

The United States National Aeronautics and Space Administration (NASA) is in the midst of a 10-year Second Generation Reusable Launch Vehicle (RLV) program to improve its space transportation capabilities for both cargo and crewed missions. The objectives of the program are to: significantly increase safety and reliability, reduce the cost of accessing low-earth orbit, attempt to leverage commercial launch capabilities, and provide a growth path for manned space exploration. The safety, reliability and life cycle cost of the next generation vehicles are major concerns, and NASA aims to achieve orders of magnitude improvement in these areas. To get these significant improvements, requires a rigorous process that addresses Reliability, Maintainability and Supportability (RMS) and safety through all the phases of the life cycle of the program. This paper discusses the RMS process being implemented for the Second Generation RLV program.

Scheme for the generation of freely traveling optical trio coherent states

NASA Astrophysics Data System (ADS)

Duc, Truong Minh; Dat, Tran Quang; An, Nguyen Ba; Kim, Jaewan

2013-08-01

Trio coherent states (TCSs) are non-Gaussian three-mode entangled states which can serve as a useful resource for continuous-variable quantum tasks, so their generation is of primary importance. Schemes exist to generate stable TCSs in terms of vibrational motion of a trapped ion inside a crystal. However, to perform quantum communication and distributed quantum computation the states should be shared beforehand among distant parties. That is, their modes should be able to be directed to different desired locations in space. In this work, we propose an experimental setup to generate such free-traveling TCSs in terms of optical fields. Our scheme uses standard physical resources, such as coherent states, balanced beam splitters, phase shifters, nonideal on-off photodetectors, and realistic weak cross-Kerr nonlinearities, without the need of single photons or homodyne or heterodyne measurements. We study the dependences of the fidelity of the state generated by our scheme with respect to the target TCS and the corresponding generation probability for the parameters involved. In theory, the fidelity could be nearly perfect for whatever weak nonlinearities τ and low photodetector efficiency η, provided that the amplitude |α| of an input coherent state is large enough, namely, |α|≥5/(ητ).

Universal quantum computation with temporal-mode bilayer square lattices

NASA Astrophysics Data System (ADS)

Alexander, Rafael N.; Yokoyama, Shota; Furusawa, Akira; Menicucci, Nicolas C.

2018-03-01

We propose an experimental design for universal continuous-variable quantum computation that incorporates recent innovations in linear-optics-based continuous-variable cluster state generation and cubic-phase gate teleportation. The first ingredient is a protocol for generating the bilayer-square-lattice cluster state (a universal resource state) with temporal modes of light. With this state, measurement-based implementation of Gaussian unitary gates requires only homodyne detection. Second, we describe a measurement device that implements an adaptive cubic-phase gate, up to a random phase-space displacement. It requires a two-step sequence of homodyne measurements and consumes a (non-Gaussian) cubic-phase state.

Power Generation from Nuclear Reactors in Aerospace Applications

NASA Technical Reports Server (NTRS)

English, Robert E.

1982-01-01

Power generation in nuclear powerplants in space is addressed. In particular, the states of technology of the principal competitive concepts for power generation are assessed. The possible impact of power conditioning on power generation is also discussed. For aircraft nuclear propulsion, the suitability of various technologies is cursorily assessed for flight in the Earth's atmosphere; a program path is suggested to ease the conditions of first use of aircraft nuclear propulsion.

High average power diode pumped solid state laser

NASA Astrophysics Data System (ADS)

Gao, Yue; Wang, Yanjie; Chan, Amy; Dawson, Murray; Greene, Ben

2017-03-01

A new generation of high average power pulsed multi-joule solid state laser system has been developed at EOS Space Systems for various space related tracking applications. It is a completely diode pumped, fully automated multi-stage system consisting of a pulsed single longitudinal mode oscillator, three stages of pre-amplifiers, two stages of power amplifiers, completely sealed phase conjugate mirror or stimulated Brillouin scattering (SBS) cell and imaging relay optics with spatial filters in vacuum cells. It is capable of generating pulse energy up to 4.7 J, a beam quality M 2 ~ 3, pulse width between 10-20 ns, and a pulse repetition rate between 100-200 Hz. The system has been in service for more than two years with excellent performance and reliability.

The Youth Space Vision for the Decade to Come: The Next Generation Network Looks Back to Look Forward

NASA Astrophysics Data System (ADS)

Cornell, Ariane

2010-05-01

The Space Generation Advisory Council in support of the United Nations Programme on Space Applications (SGAC) is a non-governmental organization of 4,000 members in 90+ countries which aims to represent university students and young space professionals to the United Nations, States, and other space agencies and organizations. In 2009, SGAC celebrated its ten year anniversary, and it was this milestone that inspired its 10 Year Anniversary Conference in June 2009, which was attended by members of the SGAC community from six continents and 21 States. The conference aimed to lead the attendees in a review of the past ten years of the politics of space as well as the "spacescape" (i.e., the overview of the organizations conducting space activities such as launching vehicles, owning satellites, or purchasing space-based services). The point of this review was to help analyze how SGAC and the youth it represents should position themselves for the next ten years. What resulted is a decadal vision from the youth (approximately 18-35 year olds) of the direction of global development and challenges, the role of the space sector in this development, and how SGAC and the youth it represents could best contribute to the development. The international community stands at a crossroads in the progress of humans in space. This paper represents a first step the youth are making in taking advantage of this watershed moment to develop an updated, pertinent role for the next ten years.

NASA's Next Generation Space Geodesy Network

NASA Technical Reports Server (NTRS)

Desai, S. D.; Gross, R. S.; Hilliard, L.; Lemoine, F. G.; Long, J. L.; Ma, C.; McGarry, J. F.; Merkowitz, S. M.; Murphy, D.; Noll, C. E.;

Towards the Next Generation of Space Environment Prediction Capabilities.

NASA Astrophysics Data System (ADS)

Kuznetsova, M. M.

2015-12-01

Since its establishment more than 15 years ago, the Community Coordinated Modeling Center (CCMC, http://ccmc.gsfc.nasa.gov) is serving as an assess point to expanding collection of state-of-the-art space environment models and frameworks as well as a hub for collaborative development of next generation space weather forecasting systems. In partnership with model developers and international research and operational communities the CCMC integrates new data streams and models from diverse sources into end-to-end space weather impacts predictive systems, identifies week links in data-model & model-model coupling and leads community efforts to fill those gaps. The presentation will highlight latest developments, progress in CCMC-led community-wide projects on testing, prototyping, and validation of models, forecasting techniques and procedures and outline ideas on accelerating implementation of new capabilities in space weather operations.

Advanced Solid State Lighting for AES Deep Space Hab Project

NASA Technical Reports Server (NTRS)

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.

Realistic facial animation generation based on facial expression mapping

NASA Astrophysics Data System (ADS)

Yu, Hui; Garrod, Oliver; Jack, Rachael; Schyns, Philippe

2014-01-01

Facial expressions reflect internal emotional states of a character or in response to social communications. Though much effort has been taken to generate realistic facial expressions, it still remains a challenging topic due to human being's sensitivity to subtle facial movements. In this paper, we present a method for facial animation generation, which reflects true facial muscle movements with high fidelity. An intermediate model space is introduced to transfer captured static AU peak frames based on FACS to the conformed target face. And then dynamic parameters derived using a psychophysics method is integrated to generate facial animation, which is assumed to represent natural correlation of multiple AUs. Finally, the animation sequence in the intermediate model space is mapped to the target face to produce final animation.

Future Photovoltaic Power Generation for Space-Based Power Utilities

NASA Technical Reports Server (NTRS)

Bailey, Sheila; Landis, Geoffrey; Hepp, Aloysius; Raffaelle, Ryne

2002-01-01

This paper discusses requirements for large earth orbiting power stations that can serve as central utilities for other orbiting spacecraft, or for beaming power to the earth itself. The current state of the art of space solar cells, and a variety of both evolving thin film cells as well as new technologies that may impact the future choice of space solar cells for high power mission applications are addressed.

Analysing generator matrices G of similar state but varying minimum determinants

NASA Astrophysics Data System (ADS)

Harun, H.; Razali, M. F.; Rahman, N. A. Abdul

2016-10-01

Since Tarokh discovered Space-Time Trellis Code (STTC) in 1998, a considerable effort has been done to improve the performance of the original STTC. One way of achieving enhancement is by focusing on the generator matrix G, which represents the encoder structure for STTC. Until now, researchers have only concentrated on STTCs of different states in analyzing the performance of generator matrix G. No effort has been made on different generator matrices G of similar state. The reason being, it is difficult to produce a wide variety of generator matrices G with diverse minimum determinants. In this paper a number of generator matrices G with minimum determinant of four (4), eight (8) and sixteen (16) of the same state (i.e., 4-PSK) have been successfully produced. The performance of different generator matrices G in term of their bit error rate and signal-to-noise ratio for a Rayleigh fading environment are compared and evaluated. It is found from the MATLAB simulation that at low SNR (<8), the BER of generator matrices G with smaller minimum determinant is comparatively lower than those of higher minimum determinant. However, at high SNR (>14) there is no significant difference between the BER of these generator matrices G.

Airframe Technology Development for Next Generation Launch Vehicles

NASA Technical Reports Server (NTRS)

Glass, David E.

2004-01-01

The Airframe subproject within NASA's Next Generation Launch Technology (NGLT) program has the responsibility to develop airframe technology for both rocket and airbreathing vehicles for access to space. The Airframe sub-project pushes the state-of-the-art in airframe technology for low-cost, reliable, and safe space transportation. Both low and medium technology readiness level (TRL) activities are being pursued. The key technical areas being addressed include design and integration, hot and integrated structures, cryogenic tanks, and thermal protection systems. Each of the technologies in these areas are discussed in this paper.

Spike-Threshold Variability Originated from Separatrix-Crossing in Neuronal Dynamics

PubMed Central

Wang, Longfei; Wang, Hengtong; Yu, Lianchun; Chen, Yong

2016-01-01

The threshold voltage for action potential generation is a key regulator of neuronal signal processing, yet the mechanism of its dynamic variation is still not well described. In this paper, we propose that threshold phenomena can be classified as parameter thresholds and state thresholds. Voltage thresholds which belong to the state threshold are determined by the ‘general separatrix’ in state space. We demonstrate that the separatrix generally exists in the state space of neuron models. The general form of separatrix was assumed as the function of both states and stimuli and the previously assumed threshold evolving equation versus time is naturally deduced from the separatrix. In terms of neuronal dynamics, the threshold voltage variation, which is affected by different stimuli, is determined by crossing the separatrix at different points in state space. We suggest that the separatrix-crossing mechanism in state space is the intrinsic dynamic mechanism for threshold voltages and post-stimulus threshold phenomena. These proposals are also systematically verified in example models, three of which have analytic separatrices and one is the classic Hodgkin-Huxley model. The separatrix-crossing framework provides an overview of the neuronal threshold and will facilitate understanding of the nature of threshold variability. PMID:27546614

Spike-Threshold Variability Originated from Separatrix-Crossing in Neuronal Dynamics.

PubMed

Wang, Longfei; Wang, Hengtong; Yu, Lianchun; Chen, Yong

2016-08-22

The threshold voltage for action potential generation is a key regulator of neuronal signal processing, yet the mechanism of its dynamic variation is still not well described. In this paper, we propose that threshold phenomena can be classified as parameter thresholds and state thresholds. Voltage thresholds which belong to the state threshold are determined by the 'general separatrix' in state space. We demonstrate that the separatrix generally exists in the state space of neuron models. The general form of separatrix was assumed as the function of both states and stimuli and the previously assumed threshold evolving equation versus time is naturally deduced from the separatrix. In terms of neuronal dynamics, the threshold voltage variation, which is affected by different stimuli, is determined by crossing the separatrix at different points in state space. We suggest that the separatrix-crossing mechanism in state space is the intrinsic dynamic mechanism for threshold voltages and post-stimulus threshold phenomena. These proposals are also systematically verified in example models, three of which have analytic separatrices and one is the classic Hodgkin-Huxley model. The separatrix-crossing framework provides an overview of the neuronal threshold and will facilitate understanding of the nature of threshold variability.

Space Technology Game Changing Development- Next Generation Life Support: Spacecraft Oxygen Recovery (SCOR)

NASA Technical Reports Server (NTRS)

Abney, Morgan; Barta, Daniel

2015-01-01

The Next Generation Life Support Spacecraft Oxygen Recovery (SCOR) project element is dedicated to developing technology that enables oxygen recovery from metabolically produced carbon dioxide in space habitats. The state-of-the-art system on the International Space Station uses Sabatier technology to recover (is) approximately 50% oxygen from carbon dioxide. The remaining oxygen required for crew respiration is supplied from Earth. For long duration manned missions beyond low-Earth orbit, resupply of oxygen becomes economically and logistically prohibitive. To mitigate these challenges, the SCOR project element is targeting development of technology to increase the recovery of oxygen to 75% or more, thereby reducing the total oxygen resupply required for future missions.

Challenges in building intelligent systems for space mission operations

NASA Technical Reports Server (NTRS)

Hartman, Wayne

1991-01-01

The purpose here is to provide a top-level look at the stewardship functions performed in space operations, and to identify the major issues and challenges that must be addressed to build intelligent systems that can realistically support operations functions. The focus is on decision support activities involving monitoring, state assessment, goal generation, plan generation, and plan execution. The bottom line is that problem solving in the space operations domain is a very complex process. A variety of knowledge constructs, representations, and reasoning processes are necessary to support effective human problem solving. Emulating these kinds of capabilities in intelligent systems offers major technical challenges that the artificial intelligence community is only beginning to address.

A Parallel Saturation Algorithm on Shared Memory Architectures

NASA Technical Reports Server (NTRS)

Ezekiel, Jonathan; Siminiceanu

2007-01-01

Symbolic state-space generators are notoriously hard to parallelize. However, the Saturation algorithm implemented in the SMART verification tool differs from other sequential symbolic state-space generators in that it exploits the locality of ring events in asynchronous system models. This paper explores whether event locality can be utilized to efficiently parallelize Saturation on shared-memory architectures. Conceptually, we propose to parallelize the ring of events within a decision diagram node, which is technically realized via a thread pool. We discuss the challenges involved in our parallel design and conduct experimental studies on its prototypical implementation. On a dual-processor dual core PC, our studies show speed-ups for several example models, e.g., of up to 50% for a Kanban model, when compared to running our algorithm only on a single core.

PMMA interlayer-modulated memory effects by space charge polarization in resistive switching based on CuSCN-nanopyramids/ZnO-nanorods p-n heterojunction

PubMed Central

Cheng, Baochang; Zhao, Jie; Xiao, Li; Cai, Qiangsheng; Guo, Rui; Xiao, Yanhe; Lei, Shuijin

2015-01-01

Resistive switching (RS) devices are commonly believed as a promising candidate for next generation nonvolatile resistance random access memory. Here, polymethylmethacrylate (PMMA) interlayer was introduced at the heterointerface of p-CuSCN hollow nanopyramid arrays and n-ZnO nanorod arrays, resulting in a typical bipolar RS behavior. We propose the mechanism of nanostructure trap-induced space charge polarization modulated by PMMA interlayer. At low reverse bias, PMMA insulator can block charges through the heterointerface, and and trapped states are respectively created on both sides of PMMA, resulting in a high resistance state (HRS) due to wider depletion region. At high reverse bias, however, electrons and holes can cross PMMA interlayer by Fowler-Nordeim tunneling due to a massive tilt of energy band, and then inject into the traps of ZnO and CuSCN, respectively. and trapped states are created, resulting in the formation of degenerate semiconductors on both sides of PMMA. Therefore, quantum tunneling and space charge polarization lead to a low resistance state (LRS). At relatively high forward bias, subsequently, the trapped states of and are recreated due to the opposite injection of charges, resulting in a recovery of HRS. The introduction of insulating interlayer at heterointerface, point a way to develop next-generation nonvolatile memories. PMID:26648249

Coherence-generating power of quantum dephasing processes

NASA Astrophysics Data System (ADS)

Styliaris, Georgios; Campos Venuti, Lorenzo; Zanardi, Paolo

2018-03-01

We provide a quantification of the capability of various quantum dephasing processes to generate coherence out of incoherent states. The measures defined, admitting computable expressions for any finite Hilbert-space dimension, are based on probabilistic averages and arise naturally from the viewpoint of coherence as a resource. We investigate how the capability of a dephasing process (e.g., a nonselective orthogonal measurement) to generate coherence depends on the relevant bases of the Hilbert space over which coherence is quantified and the dephasing process occurs, respectively. We extend our analysis to include those Lindblad time evolutions which, in the infinite-time limit, dephase the system under consideration and calculate their coherence-generating power as a function of time. We further identify specific families of such time evolutions that, although dephasing, have optimal (over all quantum processes) coherence-generating power for some intermediate time. Finally, we investigate the coherence-generating capability of random dephasing channels.

Hidden supersymmetry and quadratic deformations of the space-time conformal superalgebra

NASA Astrophysics Data System (ADS)

Yates, L. A.; Jarvis, P. D.

2018-04-01

We analyze the structure of the family of quadratic superalgebras, introduced in Jarvis et al (2011 J. Phys. A: Math. Theor. 44 235205), for the quadratic deformations of N  =  1 space-time conformal supersymmetry. We characterize in particular the ‘zero-step’ modules for this case. In such modules, the odd generators vanish identically, and the quadratic superalgebra is realized on a single irreducible representation of the even subalgebra (which is a Lie algebra). In the case under study, the quadratic deformations of N  =  1 space-time conformal supersymmetry, it is shown that each massless positive energy unitary irreducible representation (in the standard classification of Mack), forms such a zero-step module, for an appropriate parameter choice amongst the quadratic family (with vanishing central charge). For these massless particle multiplets therefore, quadratic supersymmetry is unbroken, in that the supersymmetry generators annihilate all physical states (including the vacuum state), while at the same time, superpartners do not exist.

The promise of the state space approach to time series analysis for nursing research.

PubMed

Levy, Janet A; Elser, Heather E; Knobel, Robin B

2012-01-01

Nursing research, particularly related to physiological development, often depends on the collection of time series data. The state space approach to time series analysis has great potential to answer exploratory questions relevant to physiological development but has not been used extensively in nursing. The aim of the study was to introduce the state space approach to time series analysis and demonstrate potential applicability to neonatal monitoring and physiology. We present a set of univariate state space models; each one describing a process that generates a variable of interest over time. Each model is presented algebraically and a realization of the process is presented graphically from simulated data. This is followed by a discussion of how the model has been or may be used in two nursing projects on neonatal physiological development. The defining feature of the state space approach is the decomposition of the series into components that are functions of time; specifically, slowly varying level, faster varying periodic, and irregular components. State space models potentially simulate developmental processes where a phenomenon emerges and disappears before stabilizing, where the periodic component may become more regular with time, or where the developmental trajectory of a phenomenon is irregular. The ultimate contribution of this approach to nursing science will require close collaboration and cross-disciplinary education between nurses and statisticians.

Legal and Regulatroy Obstacles to Nuclear Fission Technology in Space

NASA Astrophysics Data System (ADS)

Force, Melissa K.

2013-09-01

In forecasting the prospective use of small nuclear reactors for spacecraft and space-based power stations, the U.S. Air Force describes space as "the ultimate high ground," providing access to every part of the globe. But is it? A report titled "Energy Horizons: United States Air Force Energy Science &Technology Vision 2011-2026," focuses on core Air Force missions in space energy generation, operations and propulsion and recognizes that investments into small modular nuclear fission reactors can be leveraged for space-based systems. However, the report mentions, as an aside, that "potential catastrophic outcomes" are an element to be weighed and provides no insight into the monumental political and legal will required to overcome the mere stigma of nuclear energy, even when referring only to the most benign nuclear power generation systems - RTGs. On the heels of that report, a joint Department of Energy and NASA team published positive results from the demonstration of a uranium- powered fission reactor. The experiment was perhaps most notable for exemplifying just how effective the powerful anti-nuclear lobby has been in the United States: It was the first such demonstration of its kind in nearly fifty years. Space visionaries must anticipate a difficult war, consisting of multiple battles that must be waged in order to obtain a license to fly any but the feeblest of nuclear power sources in space. This paper aims to guide the reader through the obstacles to be overcome before nuclear fission technology can be put to use in space.

Realistic Covariance Prediction for the Earth Science Constellation

NASA Technical Reports Server (NTRS)

Duncan, Matthew; Long, Anne

2006-01-01

Routine satellite operations for the Earth Science Constellation (ESC) include collision risk assessment between members of the constellation and other orbiting space objects. One component of the risk assessment process is computing the collision probability between two space objects. The collision probability is computed using Monte Carlo techniques as well as by numerically integrating relative state probability density functions. Each algorithm takes as inputs state vector and state vector uncertainty information for both objects. The state vector uncertainty information is expressed in terms of a covariance matrix. The collision probability computation is only as good as the inputs. Therefore, to obtain a collision calculation that is a useful decision-making metric, realistic covariance matrices must be used as inputs to the calculation. This paper describes the process used by the NASA/Goddard Space Flight Center's Earth Science Mission Operations Project to generate realistic covariance predictions for three of the Earth Science Constellation satellites: Aqua, Aura and Terra.

Method of Enhancing On-Board State Estimation Using Communication Signals

NASA Technical Reports Server (NTRS)

Anzalone, Evan J. (Inventor); Chuang, Jason C. H. (Inventor)

2015-01-01

A method of enhancing on-board state estimation for a spacecraft utilizes a network of assets to include planetary-based assets and space-based assets. Communication signals transmitted from each of the assets into space are defined by a common protocol. Data is embedded in each communication signal transmitted by the assets. The data includes a time-of-transmission for a corresponding one of the communication signals and a position of a corresponding one of the assets at the time-of-transmission. A spacecraft is equipped to receive the communication signals, has a clock synchronized to the space-wide time reference frame, and has a processor programmed to generate state estimates of the spacecraft. Using its processor, the spacecraft determines a one-dimensional range from itself to at least one of the assets and then updates its state estimates using each one-dimensional range.

Fast generation of spin-squeezed states in bosonic Josephson junctions

NASA Astrophysics Data System (ADS)

Juliá-Díaz, B.; Torrontegui, E.; Martorell, J.; Muga, J. G.; Polls, A.

2012-12-01

We describe methods for the fast production of highly coherent-spin-squeezed many-body states in bosonic Josephson junctions. We start from the known mapping of the two-site Bose-Hubbard (BH) Hamiltonian to that of a single effective particle evolving according to a Schrödinger-like equation in Fock space. Since, for repulsive interactions, the effective potential in Fock space is nearly parabolic, we extend recently derived protocols for shortcuts to adiabatic evolution in harmonic potentials to the many-body BH Hamiltonian. A comparison with current experiments shows that our methods allow for an important reduction in the preparation times of highly squeezed spin states.

Advanced Solid State Lighting for Human Evaluation Project

NASA Technical Reports Server (NTRS)

Zeitlin, Nancy; Holbert, Eirik

2015-01-01

Lighting intensity and color have a significant impact on human circadian rhythms. Advanced solid state lighting was developed for the Advanced Exploration System (AES) Deep Space Habitat(DSH) concept demonstrator. The latest generation of assemblies using the latest commercially available LED lights were designed for use in the Bigelow Aerospace Environmental Control and Life Support System (ECLSS) simulator and the University of Hawaii's Hawaii Space Exploration Analog and Simulation (Hi-SEAS) habitat. Agreements with both these organizations will allow the government to receive feedback on the lights and lighting algorithms from long term human interaction.

KSC-2012-1859

NASA Image and Video Library

2012-02-17

Space Shuttle Orbiters: From its establishment in 1958, NASA studied aspects of reusable launch vehicles and spacecraft that could return to earth. On January 5, 1972, President Richard Nixon announced that the United States would develop the space shuttle, a delta-winged orbiter about the size of a DC-9 aircraft. Between the first launch on April 12, 1981, and the final landing on July 21, 2011, NASA's space shuttle fleet -- Columbia, Challenger, Discovery, Atlantis and Endeavour – launched on 135 missions, helped construct the International Space Station and inspired generations. Poster designed by Kennedy Space Center Graphics Department/Greg Lee. Credit: NASA

Space Shuttle Project

NASA Image and Video Library

1995-10-20

A Great Blue Heron seems oblivious to the tremendous spectacle of light and sound generated by a Shuttle liftoff, as the Space Shuttle Columbia (STS-73) soars skyward from Launch Pad 39B. Columbia's seven member crew's mission included continuing experimentation in the Marshall managed payloads including the United States Microgravity Laboratory 2 (USML-2) and the keel-mounted accelerometer that characterizes the very low frequency acceleration environment of the orbiter payload bay during space flight, known as the Orbital Acceleration Research Experiment (OARE).

Automatic State Space Aggregation Using a Density Based Technique

DTIC Science & Technology

2012-05-01

learner: the position of the cart X , the velocity of the cart X ′, the angle each beam makes with the cart, θ1 and θ2, and the angular velocities of the...ulation of 100 neural networks per generation, with a maximum of 200 generations of learning. Neuroevolution is provided by Another NEAT Java Implementation

Next Generation NASA Initiative for Space Geodesy

NASA Technical Reports Server (NTRS)

Merkowitz, S. M.; Desai, S.; Gross, R. S.; Hilliard, L.; Lemoine, F. G.; Long, J. L.; Ma, C.; McGarry J. F.; Murphy, D.; Noll, C. E.;

The Third International Symposium on Space Terahertz Technology: Symposium proceedings

NASA Technical Reports Server (NTRS)

1992-01-01

Papers from the symposium are presented that are relevant to the generation, detection, and use of the terahertz spectral region for space astronomy and remote sensing of the Earth's upper atmosphere. The program included thirteen sessions covering a wide variety of topics including solid-state oscillators, power-combining techniques, mixers, harmonic multipliers, antennas and antenna arrays, submillimeter receivers, and measurement techniques.

Fault tolerant testbed evaluation, phase 1

NASA Technical Reports Server (NTRS)

Caluori, V., Jr.; Newberry, T.

1993-01-01

In recent years, avionics systems development costs have become the driving factor in the development of space systems, military aircraft, and commercial aircraft. A method of reducing avionics development costs is to utilize state-of-the-art software application generator (autocode) tools and methods. The recent maturity of application generator technology has the potential to dramatically reduce development costs by eliminating software development steps that have historically introduced errors and the need for re-work. Application generator tools have been demonstrated to be an effective method for autocoding non-redundant, relatively low-rate input/output (I/O) applications on the Space Station Freedom (SSF) program; however, they have not been demonstrated for fault tolerant, high-rate I/O, flight critical environments. This contract will evaluate the use of application generators in these harsh environments. Using Boeing's quad-redundant avionics system controller as the target system, Space Shuttle Guidance, Navigation, and Control (GN&C) software will be autocoded, tested, and evaluated in the Johnson (Space Center) Avionics Engineering Laboratory (JAEL). The response of the autocoded system will be shown to match the response of the existing Shuttle General Purpose Computers (GPC's), thereby demonstrating the viability of using autocode techniques in the development of future avionics systems.

Distributed Saturation

NASA Technical Reports Server (NTRS)

Chung, Ming-Ying; Ciardo, Gianfranco; Siminiceanu, Radu I.

2007-01-01

The Saturation algorithm for symbolic state-space generation, has been a recent break-through in the exhaustive veri cation of complex systems, in particular globally-asyn- chronous/locally-synchronous systems. The algorithm uses a very compact Multiway Decision Diagram (MDD) encoding for states and the fastest symbolic exploration algo- rithm to date. The distributed version of Saturation uses the overall memory available on a network of workstations (NOW) to efficiently spread the memory load during the highly irregular exploration. A crucial factor in limiting the memory consumption during the symbolic state-space generation is the ability to perform garbage collection to free up the memory occupied by dead nodes. However, garbage collection over a NOW requires a nontrivial communication overhead. In addition, operation cache policies become critical while analyzing large-scale systems using the symbolic approach. In this technical report, we develop a garbage collection scheme and several operation cache policies to help on solving extremely complex systems. Experiments show that our schemes improve the performance of the original distributed implementation, SmArTNow, in terms of time and memory efficiency.

Nonclassicality of Photon-Added Displaced Thermal State via Quantum Phase-Space Distributions

NASA Astrophysics Data System (ADS)

Zhang, Ran; Meng, Xiang-Guo; Du, Chuan-Xun; Wang, Ji-Suo

2018-02-01

We introduce a new kind of nonclassical mixed state generated by adding arbitrary photons to a displaced thermal state, i.e., the photon-added displaced thermal state (PADTS), and obtain the normalization factor, which is simply related to two-variable Hermite polynomials. We also discuss the nonclassicality of the PADTS by considering quantum phase-space distributions. The results indicate that the value of the photon count statistics is maximum when the number of detected photons is equal to the number of added photons, and that the photon-added operation has a similar modulation effect with increasing displacement. Moreover, the negative volume of the Wigner function for the PADTS takes a maximal value for a specific photon-added number.

Formal methods for test case generation

NASA Technical Reports Server (NTRS)

Rushby, John (Inventor); De Moura, Leonardo Mendonga (Inventor); Hamon, Gregoire (Inventor)

2011-01-01

The invention relates to the use of model checkers to generate efficient test sets for hardware and software systems. The method provides for extending existing tests to reach new coverage targets; searching *to* some or all of the uncovered targets in parallel; searching in parallel *from* some or all of the states reached in previous tests; and slicing the model relative to the current set of coverage targets. The invention provides efficient test case generation and test set formation. Deep regions of the state space can be reached within allotted time and memory. The approach has been applied to use of the model checkers of SRI's SAL system and to model-based designs developed in Stateflow. Stateflow models achieving complete state and transition coverage in a single test case are reported.

Charting epilepsy by searching for intelligence in network space with the help of evolving autonomous agents.

PubMed

Ohayon, Elan L; Kalitzin, Stiliyan; Suffczynski, Piotr; Jin, Frank Y; Tsang, Paul W; Borrett, Donald S; Burnham, W McIntyre; Kwan, Hon C

2004-01-01

The problem of demarcating neural network space is formidable. A simple fully connected recurrent network of five units (binary activations, synaptic weight resolution of 10) has 3.2 *10(26) possible initial states. The problem increases drastically with scaling. Here we consider three complementary approaches to help direct the exploration to distinguish epileptic from healthy networks. [1] First, we perform a gross mapping of the space of five-unit continuous recurrent networks using randomized weights and initial activations. The majority of weight patterns (>70%) were found to result in neural assemblies exhibiting periodic limit-cycle oscillatory behavior. [2] Next we examine the activation space of non-periodic networks demonstrating that the emergence of paroxysmal activity does not require changes in connectivity. [3] The next challenge is to focus the search of network space to identify networks with more complex dynamics. Here we rely on a major available indicator critical to clinical assessment but largely ignored by epilepsy modelers, namely: behavioral states. To this end, we connected the above network layout to an external robot in which interactive states were evolved. The first random generation showed a distribution in line with approach [1]. That is, the predominate phenotypes were fixed-point or oscillatory with seizure-like motor output. As evolution progressed the profile changed markedly. Within 20 generations the entire population was able to navigate a simple environment with all individuals exhibiting multiply-stable behaviors with no cases of default locked limit-cycle oscillatory motor behavior. The resultant population may thus afford us a view of the architectural principles demarcating healthy biological networks from the pathological. The approach has an advantage over other epilepsy modeling techniques in providing a way to clarify whether observed dynamics or suggested therapies are pointing to computational viability or dead space.

Universality of emergent states in diverse physical systems

NASA Astrophysics Data System (ADS)

Guidry, Mike

2017-12-01

Our physics textbooks are dominated by examples of simple weakly-interacting microscopic states, but most of the real world around us is most effectively described in terms of emergent states that have no clear connection to simple textbook states. Emergent states are strongly-correlated and dominated by properties that emerge as a consequence of interactions and are not part of the description of the corresponding weakly-interacting system. This paper proposes a connection of weakly-interacting textbook states and realistic emergent states through fermion dynamical symmetries having fully-microscopic generators of the emergent states. These imply unique truncation of the Hilbert space for the weakly-interacting system to a collective subspace where the emergent states live. Universality arises because the possible symmetries under commutation of generators, which transcend the microscopic structure of the generators, are highly restricted in character and determine the basic structure of the emergent state, with the microscopic structure of the generators influencing emergent state only parametrically. In support of this idea we show explicit evidence that high-temperature superconductors, collective states in heavy atomic nuclei, and graphene quantum Hall states in strong magnetic fields exhibit a near-universal emergent behavior in their microscopically-computed total energy surfaces, even though these systems share essentially nothing in common at the microscopic level and their emergent states are characterized by fundamentally different order parameters.

The role of space related non-governmental organizations (NGOs) in capacity building

NASA Astrophysics Data System (ADS)

Lukaszczyk, A.; Williamson, R.

2010-02-01

Non-governmental organizations (NGOs) play a unique role in international affairs, providing access to resources, expertise, and assistance to supplement State resources. Sometimes the diplomatic skills and unofficial access of NGOs to policymakers through Track Two diplomacy can move a previously stalled critical issue forward and assist policymakers from different countries to find common ground outside official channels. Because they work outside of official channels, they are not bound by State policy that may inhibit negotiations between States. Some also have a convening power that sometimes makes it possible for State representatives to meet discipline experts and each other for informal discussions on issues of mutual interest. Finally, NGOs can draw attention to issues that may be overlooked or avoided by State organizations. This paper examines the ways in which NGOs can assist in building scientific, technical, educational, and legal and policy expertise related to space and Earth science, technology and governance of space activities. In particular, it will explore and analyze the ways in which organizations such as the Space Generation Advisory Council, EURISY, the Planetary Society and Secure World Foundation contribute to building capacity in developing countries.

Separability and Entanglement in the Hilbert Space Reference Frames Related Through the Generic Unitary Transform for Four Level System

NASA Astrophysics Data System (ADS)

Man'ko, V. I.; Markovich, L. A.

2018-02-01

Quantum correlations in the state of four-level atom are investigated by using generic unitary transforms of the classical (diagonal) density matrix. Partial cases of pure state, X-state, Werner state are studied in details. The geometrical meaning of unitary Hilbert reference-frame rotations generating entanglement in the initially separable state is discussed. Characteristics of the entanglement in terms of concurrence, entropy and negativity are obtained as functions of the unitary matrix rotating the reference frame.

State-space decoding of primary afferent neuron firing rates

NASA Astrophysics Data System (ADS)

Wagenaar, J. B.; Ventura, V.; Weber, D. J.

2011-02-01

Kinematic state feedback is important for neuroprostheses to generate stable and adaptive movements of an extremity. State information, represented in the firing rates of populations of primary afferent (PA) neurons, can be recorded at the level of the dorsal root ganglia (DRG). Previous work in cats showed the feasibility of using DRG recordings to predict the kinematic state of the hind limb using reverse regression. Although accurate decoding results were attained, reverse regression does not make efficient use of the information embedded in the firing rates of the neural population. In this paper, we present decoding results based on state-space modeling, and show that it is a more principled and more efficient method for decoding the firing rates in an ensemble of PA neurons. In particular, we show that we can extract confounded information from neurons that respond to multiple kinematic parameters, and that including velocity components in the firing rate models significantly increases the accuracy of the decoded trajectory. We show that, on average, state-space decoding is twice as efficient as reverse regression for decoding joint and endpoint kinematics.

A Locally Optimal Algorithm for Estimating a Generating Partition from an Observed Time Series and Its Application to Anomaly Detection.

PubMed

Ghalyan, Najah F; Miller, David J; Ray, Asok

2018-06-12

Estimation of a generating partition is critical for symbolization of measurements from discrete-time dynamical systems, where a sequence of symbols from a (finite-cardinality) alphabet may uniquely specify the underlying time series. Such symbolization is useful for computing measures (e.g., Kolmogorov-Sinai entropy) to identify or characterize the (possibly unknown) dynamical system. It is also useful for time series classification and anomaly detection. The seminal work of Hirata, Judd, and Kilminster (2004) derives a novel objective function, akin to a clustering objective, that measures the discrepancy between a set of reconstruction values and the points from the time series. They cast estimation of a generating partition via the minimization of their objective function. Unfortunately, their proposed algorithm is nonconvergent, with no guarantee of finding even locally optimal solutions with respect to their objective. The difficulty is a heuristic-nearest neighbor symbol assignment step. Alternatively, we develop a novel, locally optimal algorithm for their objective. We apply iterative nearest-neighbor symbol assignments with guaranteed discrepancy descent, by which joint, locally optimal symbolization of the entire time series is achieved. While most previous approaches frame generating partition estimation as a state-space partitioning problem, we recognize that minimizing the Hirata et al. (2004) objective function does not induce an explicit partitioning of the state space, but rather the space consisting of the entire time series (effectively, clustering in a (countably) infinite-dimensional space). Our approach also amounts to a novel type of sliding block lossy source coding. Improvement, with respect to several measures, is demonstrated over popular methods for symbolizing chaotic maps. We also apply our approach to time-series anomaly detection, considering both chaotic maps and failure application in a polycrystalline alloy material.

Nucleon Axial and Electromagnetic Form Factors

NASA Astrophysics Data System (ADS)

Jang, Yong-Chull; Bhattacharya, Tanmoy; Gupta, Rajan; Lin, Huey-Wen; Yoon, Boram

2018-03-01

We present results for the isovector axial, induced pseudoscalar, electric, and magnetic form factors of the nucleon. The calculations were done using 2 + 1 + 1-flavor HISQ ensembles generated by the MILC collaboration with lattice spacings a ≈ 0.12, 0.09, 0.06 fm and pion masses Mπ ≈ 310, 220, 130 MeV. Excited-states contamination is controlled by using four-state fits to two-point correlators and by comparing two-versus three-states in three-point correlators. The Q2 behavior is analyzed using the model independent z-expansion and the dipole ansatz. Final results for the charge radii and magnetic moment are obtained using a simultaneous fit in Mπ, lattice spacing a and finite volume.

Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

The design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator is presented. The intended applications of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37 to 43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37-43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37 to 43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

Natural vacuum electronics

NASA Technical Reports Server (NTRS)

Leggett, Nickolaus

1990-01-01

The ambient natural vacuum of space is proposed as a basis for electron valves. Each valve is an electron controlling structure similiar to a vacuum tube that is operated without a vacuum sustaining envelope. The natural vacuum electron valves discussed offer a viable substitute for solid state devices. The natural vacuum valve is highly resistant to ionizing radiation, system generated electromagnetic pulse, current transients, and direct exposure to space conditions.

International Space Station (ISS)

NASA Image and Video Library

1998-11-08

Designed by the STS-88 crew members, this patch commemorates the first assembly flight to carry United States-built hardware for constructing the International Space Station (ISS). This flight's primary task was to assemble the cornerstone of the Space Station: the Node with the Functional Cargo Block (FGB). The rising sun symbolizes the dawning of a new era of international cooperation in space and the beginning of a new program: the International Space Station. The Earth scene outlines the countries of the Station Partners: the United States, Russia, those of the European Space Agency (ESA), Japan, and Canada. Along with the Pressurized Mating Adapters (PMA) and the Functional Cargo Block, the Node is shown in the final mated configuration while berthed to the Space Shuttle during the STS-88/2A mission. The Big Dipper Constellation points the way to the North Star, a guiding light for pioneers and explorers for generations. In the words of the crew, These stars symbolize the efforts of everyone, including all the countries involved in the design and construction of the International Space Station, guiding us into the future.

Integrated generation of complex optical quantum states and their coherent control

NASA Astrophysics Data System (ADS)

Roztocki, Piotr; Kues, Michael; Reimer, Christian; Romero Cortés, Luis; Sciara, Stefania; Wetzel, Benjamin; Zhang, Yanbing; Cino, Alfonso; Chu, Sai T.; Little, Brent E.; Moss, David J.; Caspani, Lucia; Azaña, José; Morandotti, Roberto

2018-01-01

Complex optical quantum states based on entangled photons are essential for investigations of fundamental physics and are the heart of applications in quantum information science. Recently, integrated photonics has become a leading platform for the compact, cost-efficient, and stable generation and processing of optical quantum states. However, onchip sources are currently limited to basic two-dimensional (qubit) two-photon states, whereas scaling the state complexity requires access to states composed of several (<2) photons and/or exhibiting high photon dimensionality. Here we show that the use of integrated frequency combs (on-chip light sources with a broad spectrum of evenly-spaced frequency modes) based on high-Q nonlinear microring resonators can provide solutions for such scalable complex quantum state sources. In particular, by using spontaneous four-wave mixing within the resonators, we demonstrate the generation of bi- and multi-photon entangled qubit states over a broad comb of channels spanning the S, C, and L telecommunications bands, and control these states coherently to perform quantum interference measurements and state tomography. Furthermore, we demonstrate the on-chip generation of entangled high-dimensional (quDit) states, where the photons are created in a coherent superposition of multiple pure frequency modes. Specifically, we confirm the realization of a quantum system with at least one hundred dimensions. Moreover, using off-the-shelf telecommunications components, we introduce a platform for the coherent manipulation and control of frequencyentangled quDit states. Our results suggest that microcavity-based entangled photon state generation and the coherent control of states using accessible telecommunications infrastructure introduce a powerful and scalable platform for quantum information science.

Fact Sheet: National Space Policy. Appendix F-2

NASA Technical Reports Server (NTRS)

1996-01-01

For over three decades, the United States has led the world in the exploration and use of outer space. Our achievements in space have inspired a generation of Americans and people throughout the world. We will maintain this leadership role by supporting a strong, stable, and balanced national space program that serves our goals in national security, foreign policy, economic growth, environmental stewardship, and scientific and technical excellence. Access to and use of space are central for preserving peace and protecting US national security as well as civil and commercial interests. The United States will pursue greater levels of partnership and cooperation in national and international space activities and work with other nations to ensure the continued exploration and use of outer space for peaceful purposes. The goals of the US space program are to: (a) Enhance knowledge of the Earth, the solar system, and the universe through human and robotic exploration; (b) Strengthen and maintain the national security of the United States; (c) Enhance the economic competitiveness and scientific and technical capabilities of the United States; (d) Encourage State, local, and private sector investment in, and use of, space technologies; (e) Promote international cooperation to further US domestic, national security, and foreign policies. The United States is committed to the exploration and use of outer space by all nations for peaceful purposes and for the benefit of all humanity. "Peaceful purposes" allow defense and intelligence-related activities in pursuit of national security and other goals. The United States rejects any claims to sovereignty by any nation over outer space or celestial bodies, or any portion thereof, and rejects any limitations on the fundamental right of sovereign nations to acquire data from space. The United States considers the space systems of any nation to be national property with the right of passage through and operations in space without interference. Purposeful interference with space systems shall be viewed as an infringement on sovereign rights. The US Government will maintain and coordinate separate national security and civil space systems where differing needs dictate. All actions undertaken by agencies and departments in implementing the national space policy shall be consistent with US law, regulations, national security requirements, foreign policy, international obligations, and nonproliferation policy. The National Science and Technology Council (NSTC) is the principal forum for resolving issues related to national space policy. As appropriate, the NSTC and NSC will co-chair policy process. This policy will be implemented within the overall resource and policy guidance provided by the President.

Superconducting magnet cooling system

DOEpatents

Vander Arend, Peter C.; Fowler, William B.

1977-01-01

A device is provided for cooling a conductor to the superconducting state. The conductor is positioned within an inner conduit through which is flowing a supercooled liquid coolant in physical contact with the conductor. The inner conduit is positioned within an outer conduit so that an annular open space is formed therebetween. Through the annular space is flowing coolant in the boiling liquid state. Heat generated by the conductor is transferred by convection within the supercooled liquid coolant to the inner wall of the inner conduit and then is removed by the boiling liquid coolant, making the heat removal from the conductor relatively independent of conductor length.

Generation of squeezing in a driven many-body system

NASA Astrophysics Data System (ADS)

Hebbe Madhusudhana, Bharath; Boguslawski, Matthew; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael

2016-05-01

In a spin-1 Bose-Einstein condensate, the non-linear spin-dependent collisional interactions can create entanglement and squeezing. Typically, the condensate is initialized at an unstable fixed point of the phase space, and subsequent free evolution under a time-independent Hamiltonian creates the squeezed state. Alternatively, it is possible to generate squeezing by driving the system localized at a stable fixed point. Here, we demonstrate that periodic modulation of the Hamiltonian can generate highly squeezed states. Our measurements show -5 dB of squeezing, limited by the detection, but calculations indicate that a theoretical potential of -20 dB of squeezing. We discuss the advantages of this method compared with the typical techniques.

Human transient into-the-loop simulation for NGATS

DOT National Transportation Integrated Search

2006-08-21

Serious planning is underway for the United States Next Generation Air Transportation System. While design decisions are far from complete, there is consideration of having aircraft-trajectory control in space and time be determined by some combinati...

International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

NASA Technical Reports Server (NTRS)

Erickson, Robert J.; Howe, John, Jr.; Kulp, Galen W.; VanKeuren, Steven P.

2008-01-01

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Space Transportation Propulsion Technology Symposium. Volume 3: Panel Session Summaries and Presentations

NASA Technical Reports Server (NTRS)

1991-01-01

The Space Transportation Propulsion Technology Symposium was held at the Pennsylvania State University on June 25 to 29, 1990. Emphasis was placed on propulsion requirements and initiatives to support current, next generation, and future space transportation systems, with the primary objectives of discerning whether proposed designs truly meet future transportation needs and identifying possible technology gaps, overlaps and other programmatic deficiencies. Key space transportation propulsion issues are addressed through four panels with government, industry, and academia membership. The panel focused on systems engineering and integration; development, manufacturing, and certification; operational efficiency; program development; and cultural issues.

Realization of non-linear coherent states by photonic lattices

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

Dehdashti, Shahram, E-mail: shdehdashti@zju.edu.cn; Li, Rujiang; Chen, Hongsheng, E-mail: hansomchen@zju.edu.cn

2015-06-15

In this paper, first, by introducing Holstein-Primakoff representation of α-deformed algebra, we achieve the associated non-linear coherent states, including su(2) and su(1, 1) coherent states. Second, by using waveguide lattices with specific coupling coefficients between neighbouring channels, we generate these non-linear coherent states. In the case of positive values of α, we indicate that the Hilbert size space is finite; therefore, we construct this coherent state with finite channels of waveguide lattices. Finally, we study the field distribution behaviours of these coherent states, by using Mandel Q parameter.

Heat operated cryogenic electrical generator

NASA Technical Reports Server (NTRS)

Wang, T. G.; Saffren, M. M.; Elleman, D. D. (Inventor)

1975-01-01

An electrical generator useful for providing electrical power in deep space, is disclosed. The electrical generator utilizes the unusual hydrodynamic property exhibited by liquid helium as it is converted to and from a superfluid state to cause opposite directions of rotary motion for a rotor cell thereof. The physical motion of the rotor cell was employed to move a magnetic field provided by a charged superconductive coil mounted on the exterior of the cell. An electrical conductor was placed in surrounding proximity to the cell to interact with the moving magnetic field provided by the superconductive coil and thereby generate electrical energy. A heat control arrangement was provided for the purpose of causing the liquid helium to be partially converted to and from a superfluid state by being cooled and heated, respectively.

Dual Vector Spaces and Physical Singularities

NASA Astrophysics Data System (ADS)

Rowlands, Peter

Though we often refer to 3-D vector space as constructed from points, there is no mechanism from within its definition for doing this. In particular, space, on its own, cannot accommodate the singularities that we call fundamental particles. This requires a commutative combination of space as we know it with another 3-D vector space, which is dual to the first (in a physical sense). The combination of the two spaces generates a nilpotent quantum mechanics/quantum field theory, which incorporates exact supersymmetry and ultimately removes the anomalies due to self-interaction. Among the many natural consequences of the dual space formalism are half-integral spin for fermions, zitterbewegung, Berry phase and a zero norm Berwald-Moor metric for fermionic states.

Self-starting harmonic frequency comb generation in a quantum cascade laser

NASA Astrophysics Data System (ADS)

Kazakov, Dmitry; Piccardo, Marco; Wang, Yongrui; Chevalier, Paul; Mansuripur, Tobias S.; Xie, Feng; Zah, Chung-en; Lascola, Kevin; Belyanin, Alexey; Capasso, Federico

2017-12-01

Optical frequency combs1,2 establish a rigid phase-coherent link between microwave and optical domains and are emerging as high-precision tools in an increasing number of applications3. Frequency combs with large intermodal spacing are employed in the field of microwave photonics for radiofrequency arbitrary waveform synthesis4,5 and for the generation of terahertz tones of high spectral purity in future wireless communication networks6,7. Here, we demonstrate self-starting harmonic frequency comb generation with a terahertz repetition rate in a quantum cascade laser. The large intermodal spacing caused by the suppression of tens of adjacent cavity modes originates from a parametric contribution to the gain due to temporal modulations of population inversion in the laser8,9. Using multiheterodyne self-detection, the mode spacing of the harmonic comb is shown to be uniform to within 5 × 10-12 parts of the central frequency. This new harmonic comb state extends the range of applications of quantum cascade laser frequency combs10-13.

Qualia: The Geometry of Integrated Information

PubMed Central

Balduzzi, David; Tononi, Giulio

2009-01-01

According to the integrated information theory, the quantity of consciousness is the amount of integrated information generated by a complex of elements, and the quality of experience is specified by the informational relationships it generates. This paper outlines a framework for characterizing the informational relationships generated by such systems. Qualia space (Q) is a space having an axis for each possible state (activity pattern) of a complex. Within Q, each submechanism specifies a point corresponding to a repertoire of system states. Arrows between repertoires in Q define informational relationships. Together, these arrows specify a quale—a shape that completely and univocally characterizes the quality of a conscious experience. Φ— the height of this shape—is the quantity of consciousness associated with the experience. Entanglement measures how irreducible informational relationships are to their component relationships, specifying concepts and modes. Several corollaries follow from these premises. The quale is determined by both the mechanism and state of the system. Thus, two different systems having identical activity patterns may generate different qualia. Conversely, the same quale may be generated by two systems that differ in both activity and connectivity. Both active and inactive elements specify a quale, but elements that are inactivated do not. Also, the activation of an element affects experience by changing the shape of the quale. The subdivision of experience into modalities and submodalities corresponds to subshapes in Q. In principle, different aspects of experience may be classified as different shapes in Q, and the similarity between experiences reduces to similarities between shapes. Finally, specific qualities, such as the “redness” of red, while generated by a local mechanism, cannot be reduced to it, but require considering the entire quale. Ultimately, the present framework may offer a principled way for translating qualitative properties of experience into mathematics. PMID:19680424

Large Aperture Systems: 2000-2004

NASA Technical Reports Server (NTRS)

2004-01-01

This custom bibliography from the NASA Scientific and Technical Information Program lists a sampling of records found in the NASA Aeronautics and Space Database. The scope of this topic includes technologies for next generation astronomical telescopes and detectors. This area of focus is one of the enabling technologies as defined by NASA s Report of the President s Commission on Implementation of United States Space Exploration Policy, published in June 2004.

2006 Program of Study: Ice

DTIC Science & Technology

2007-03-01

Balmforth University of British Columbia Andrew Belmonte Penn State University Robert Bindschadler NASA Goddard Space Flight Center Goran Bjork Goteborg...Friday, July 7 10:30 AM Charles Doering, University of Michigan Twist and shout ! Maximal enstrophy generation in the 3-D Navier-Stokes equation July 10...shear flows Thursday, July 27 10:30 AM Robert Bindschadler, NASA Goddard Space Flight Center The new view of ice sheet dynamics 2:30 PM Petri Fast

STS-88 Mission Insignia

NASA Technical Reports Server (NTRS)

1998-01-01

Designed by the STS-88 crew members, this patch commemorates the first assembly flight to carry United States-built hardware for constructing the International Space Station (ISS). This flight's primary task was to assemble the cornerstone of the Space Station: the Node with the Functional Cargo Block (FGB). The rising sun symbolizes the dawning of a new era of international cooperation in space and the beginning of a new program: the International Space Station. The Earth scene outlines the countries of the Station Partners: the United States, Russia, those of the European Space Agency (ESA), Japan, and Canada. Along with the Pressurized Mating Adapters (PMA) and the Functional Cargo Block, the Node is shown in the final mated configuration while berthed to the Space Shuttle during the STS-88/2A mission. The Big Dipper Constellation points the way to the North Star, a guiding light for pioneers and explorers for generations. In the words of the crew, These stars symbolize the efforts of everyone, including all the countries involved in the design and construction of the International Space Station, guiding us into the future.

Solid-State Power Generating Microdevices for Distributed Space System Architectures

NASA Technical Reports Server (NTRS)

Fleurial, J.-P.; Patel, J.; Snyder, G. J.; Huang, C.-K.; Averback, R.; Hill, C.; Chen, G.

2001-01-01

Deep space missions have a strong need for compact, high power density, reliable and long life electrical power generation and storage under extreme temperature conditions. Conventional power generating devices become inefficient at very low temperatures (temperatures lower than 200 K encountered during Mars missions for example) and rechargeable energy storage devices cannot be operated thereby limiting mission duration. At elevated temperatures (for example for planned solar probe or Venus lander missions), thin film interdiffusion destroys electronic devices used for generating and storing power. Solar power generation strongly depends upon the light intensity, which falls rapidly in deep interplanetary missions (beyond 5 AU), and in planetary missions in the sun shadow or in dusty environments (Mars, for example). Radioisotope thermoelectric generators (RTGs) have been successfully used for a number of deep space missions RTGs. However, their energy conversion efficiency and specific power characteristics are quite low, and this technology has been limited to relatively large systems (more than 100 W). The National Aeronautics and Space Administration (NASA) and the Jet Propulsion Laboratory (JPL) have been planning the use of much smaller spacecrafts that will incorporate a variety of microdevices and miniature vehicles such as microdetectors, microsensors, and microrovers. Except for electrochemical batteries and solar cells, there are currently no available miniaturized power sources. Novel technologies that will function reliably over a long duration mission (ten years and over), in harsh environments (temperature, pressure, and atmosphere) must be developed to enable the success of future space missions. It is also expected that such micropower sources could have a wide range of terrestrial applications, in particular when the limited lifetime and environmental limitations of batteries are key factors. Additional information is contained in the original extended abstract.

Bayesian state space models for dynamic genetic network construction across multiple tissues.

PubMed

Liang, Yulan; Kelemen, Arpad

2016-08-01

Construction of gene-gene interaction networks and potential pathways is a challenging and important problem in genomic research for complex diseases while estimating the dynamic changes of the temporal correlations and non-stationarity are the keys in this process. In this paper, we develop dynamic state space models with hierarchical Bayesian settings to tackle this challenge for inferring the dynamic profiles and genetic networks associated with disease treatments. We treat both the stochastic transition matrix and the observation matrix time-variant and include temporal correlation structures in the covariance matrix estimations in the multivariate Bayesian state space models. The unevenly spaced short time courses with unseen time points are treated as hidden state variables. Hierarchical Bayesian approaches with various prior and hyper-prior models with Monte Carlo Markov Chain and Gibbs sampling algorithms are used to estimate the model parameters and the hidden state variables. We apply the proposed Hierarchical Bayesian state space models to multiple tissues (liver, skeletal muscle, and kidney) Affymetrix time course data sets following corticosteroid (CS) drug administration. Both simulation and real data analysis results show that the genomic changes over time and gene-gene interaction in response to CS treatment can be well captured by the proposed models. The proposed dynamic Hierarchical Bayesian state space modeling approaches could be expanded and applied to other large scale genomic data, such as next generation sequence (NGS) combined with real time and time varying electronic health record (EHR) for more comprehensive and robust systematic and network based analysis in order to transform big biomedical data into predictions and diagnostics for precision medicine and personalized healthcare with better decision making and patient outcomes.

Structured decomposition design of partial Mueller matrix polarimeters.

PubMed

Alenin, Andrey S; Scott Tyo, J

2015-07-01

Partial Mueller matrix polarimeters (pMMPs) are active sensing instruments that probe a scattering process with a set of polarization states and analyze the scattered light with a second set of polarization states. Unlike conventional Mueller matrix polarimeters, pMMPs do not attempt to reconstruct the entire Mueller matrix. With proper choice of generator and analyzer states, a subset of the Mueller matrix space can be reconstructed with fewer measurements than that of the full Mueller matrix polarimeter. In this paper we consider the structure of the Mueller matrix and our ability to probe it using a reduced number of measurements. We develop analysis tools that allow us to relate the particular choice of generator and analyzer polarization states to the portion of Mueller matrix space that the instrument measures, as well as develop an optimization method that is based on balancing the signal-to-noise ratio of the resulting instrument with the ability of that instrument to accurately measure a particular set of desired polarization components with as few measurements as possible. In the process, we identify 10 classes of pMMP systems, for which the space coverage is immediately known. We demonstrate the theory with a numerical example that designs partial polarimeters for the task of monitoring the damage state of a material as presented earlier by Hoover and Tyo [Appl. Opt.46, 8364 (2007)10.1364/AO.46.008364APOPAI1559-128X]. We show that we can reduce the polarimeter to making eight measurements while still covering the Mueller matrix subspace spanned by the objects.

Space Weather Products at the Community Coordinated Modeling Center

NASA Technical Reports Server (NTRS)

Hesse, Michael; Kuznetsova, M.; Pulkkinen, A.; Maddox, M.; Rastaetter, L.; Berrios, D.; MacNeice, P.

2010-01-01

The Community Coordinated Modeling Center (CCMC) is a US inter-agency activity aiming at research in support of the generation of advanced space weather models. As one of its main functions, the CCMC provides to researchers the use of space science models, even if they are not model owners themselves. The second CCMC activity is to support Space Weather forecasting at national Space Weather Forecasting Centers. This second activity involves model evaluations, model transitions to operations, and the development of space weather forecasting tools. Owing to the pace of development in the science community, new model capabilities emerge frequently. Consequently, space weather products and tools involve not only increased validity, but often entirely new capabilities. This presentation will review the present state of space weather tools as well as point out emerging future capabilities.

A mesh gradient technique for numerical optimization

NASA Technical Reports Server (NTRS)

Willis, E. A., Jr.

1973-01-01

A class of successive-improvement optimization methods in which directions of descent are defined in the state space along each trial trajectory are considered. The given problem is first decomposed into two discrete levels by imposing mesh points. Level 1 consists of running optimal subarcs between each successive pair of mesh points. For normal systems, these optimal two-point boundary value problems can be solved by following a routine prescription if the mesh spacing is sufficiently close. A spacing criterion is given. Under appropriate conditions, the criterion value depends only on the coordinates of the mesh points, and its gradient with respect to those coordinates may be defined by interpreting the adjoint variables as partial derivatives of the criterion value function. In level 2, the gradient data is used to generate improvement steps or search directions in the state space which satisfy the boundary values and constraints of the given problem.

Human Activity Behavior and Gesture Generation in Virtual Worlds for Long- Duration Space Missions. Chapter 8

NASA Technical Reports Server (NTRS)

Sierhuis, Maarten; Clancey, William J.; Damer, Bruce; Brodsky, Boris; vanHoff, Ron

2007-01-01

A virtual worlds presentation technique with embodied, intelligent agents is being developed as an instructional medium suitable to present in situ training on long term space flight. The system combines a behavioral element based on finite state automata, a behavior based reactive architecture also described as subsumption architecture, and a belief-desire-intention agent structure. These three features are being integrated to describe a Brahms virtual environment model of extravehicular crew activity which could become a basis for procedure training during extended space flight.

Reducing a Knowledge-Base Search Space When Data Are Missing

NASA Technical Reports Server (NTRS)

James, Mark

2007-01-01

This software addresses the problem of how to efficiently execute a knowledge base in the presence of missing data. Computationally, this is an exponentially expensive operation that without heuristics generates a search space of 1 + 2n possible scenarios, where n is the number of rules in the knowledge base. Even for a knowledge base of the most modest size, say 16 rules, it would produce 65,537 possible scenarios. The purpose of this software is to reduce the complexity of this operation to a more manageable size. The problem that this system solves is to develop an automated approach that can reason in the presence of missing data. This is a meta-reasoning capability that repeatedly calls a diagnostic engine/model to provide prognoses and prognosis tracking. In the big picture, the scenario generator takes as its input the current state of a system, including probabilistic information from Data Forecasting. Using model-based reasoning techniques, it returns an ordered list of fault scenarios that could be generated from the current state, i.e., the plausible future failure modes of the system as it presently stands. The scenario generator models a Potential Fault Scenario (PFS) as a black box, the input of which is a set of states tagged with priorities and the output of which is one or more potential fault scenarios tagged by a confidence factor. The results from the system are used by a model-based diagnostician to predict the future health of the monitored system.

Back to the Future: Consistency-Based Trajectory Tracking

NASA Technical Reports Server (NTRS)

Kurien, James; Nayak, P. Pandurand; Norvig, Peter (Technical Monitor)

2000-01-01

Given a model of a physical process and a sequence of commands and observations received over time, the task of an autonomous controller is to determine the likely states of the process and the actions required to move the process to a desired configuration. We introduce a representation and algorithms for incrementally generating approximate belief states for a restricted but relevant class of partially observable Markov decision processes with very large state spaces. The algorithm presented incrementally generates, rather than revises, an approximate belief state at any point by abstracting and summarizing segments of the likely trajectories of the process. This enables applications to efficiently maintain a partial belief state when it remains consistent with observations and revisit past assumptions about the process' evolution when the belief state is ruled out. The system presented has been implemented and results on examples from the domain of spacecraft control are presented.

Development of Extravehicular Visor Assembly (EVVA)

NASA Technical Reports Server (NTRS)

Davis, Kristine

2017-01-01

For the next generation of NASA's space suits, being able to enable an architecture for microgravity and planetary capabilities is required. To support these future missions, we will need exemplary support hardware to be designed, such as a new extravehicular visor assembly (EVVA). This EVVA will carry out its heritage mission of protecting the astronauts' eyes from harmful radiation, giving needed shade, and providing thermal protection, while also incorporating new designs that maximize overhead visibility and incorporate new technology. It will be designed to adapt with xEMU lite, a next-generation suit architecture Completed market research and literature reviews center dotSet up a NASA@Workchallenge "Incorporating Active TintableElectronic Coatings into Next Generation Space Suit Visor." center dotContacted Boeing and AlphaMicron to understand COTS solutions on the market and how they could be applied to the space suit design. oFound that there are many advantages to an active coating because of reduced mechanisms, an inherent dust tolerant design, and auto-sense capabilities. However, the COTS designs are not currently compatible with the xEMU lite form factor, the space environment, and the xEMU lite power requirement. COTS designs can also fail in the off/transparent state. center dotPursuing low TRL funding sources for future development for exploration EVA space suit Boeing 787

Private space exploration: A new way for starting a spacefaring society?

NASA Astrophysics Data System (ADS)

Genta, Giancarlo

2014-11-01

Since the beginning space was an exclusive domain of public organizations, the role of privates is becoming more and more important, and not only in commercial activities. However, the main international treaties dealing with this subject are still based on the assumption that space activities are mostly reserved to states. In the last decade the idea that the role of privates could include the management of space infrastructures and launch vehicles gained support and now private launch services are a reality. An even wider role of privates is now advocated and private exploration and exploitation missions are discussed. This requires that space activity in general can generate an attractive return and those business models are identified.

Light scalars on cosmological backgrounds

NASA Astrophysics Data System (ADS)

Markkanen, Tommi

2018-01-01

We study the behaviour of a light quartically self-interacting scalar field ϕ on curved backgrounds that may be described with the cosmological equation state parameter w. At leading order in the non-perturbative 2PI expansion we find a general formula for the variance < {\\widehat{φ}}^2> and show for several previously unexplored cases, including matter domination and kination, that the curvature of space can induce a significant excitation of the field. We discuss how the generation of a non-zero variance for w ≠ -1 can be understood as a process of self-regulation of the infrared divergences very similarly to what is known to occur in de Sitter space. To conclude, the appearance of an effective mass due to self-interaction is generic for a light scalar in curved space and can have important implications for reheating, vacuum stability and dark matter generation.

The origin of non-classical effects in a one-dimensional superposition of coherent states

NASA Technical Reports Server (NTRS)

Buzek, V.; Knight, P. L.; Barranco, A. Vidiella

1992-01-01

We investigate the nature of the quantum fluctuations in a light field created by the superposition of coherent fields. We give a physical explanation (in terms of Wigner functions and phase-space interference) why the 1-D superposition of coherent states in the direction of the x-quadrature leads to the squeezing of fluctuations in the y-direction, and show that such a superposition can generate the squeezed vacuum and squeezed coherent states.

Chemical suicides in automobiles--six states, 2006-2010.

PubMed

2011-09-09

During a 3-month period in 2008 in Japan, 208 persons committed suicide by mixing household chemicals and, while in a confined space, breathing in the resultant poisonous gas. The large number of similar suicides is believed to have resulted from the posting of directions for generating poisonous gas on the Internet. In addition to claiming the suicide victim, lethal gas generated by intentionally mixing household chemicals can leak from confined spaces, triggering evacuations, and exposing bystanders and first responders to injury. Chemical suicides similar to those in Japan in 2008 have been reported increasingly in the United States, with the majority occurring inside automobiles. To characterize such incidents in the United States, the Agency for Toxic Substances and Disease Registry (ATSDR) analyzed reports of chemical suicides and attempted suicides that occurred in automobiles, using 2006--2009 data from states participating in the Hazardous Substances Emergency Events Surveillance (HSEES) system and 2010 data from states participating in the new National Toxic Substance Incidents Program (NTSIP). This report summarizes the results of that analysis, which found that, during 2006--2010, a total of 10 chemical suicide incidents were reported from six states, resulting in the deaths of nine suicide victims and injuries to four law enforcement officers. When responding to suspected chemical suicide incidents, emergency responders must take precautions to ensure both their safety and the safety of any bystanders in the immediate vicinity.

Research pressure instrumentation for NASA Space Shuttle main engine, modification no. 5

NASA Technical Reports Server (NTRS)

Anderson, P. J.; Nussbaum, P.; Gustafson, G.

1984-01-01

The objective of the research project described is to define and demonstrate methods to advance the state of the art of pressure sensors for the space shuttle main engine (SSME). Silicon piezoresistive technology was utilized in completing tasks: generation and testing of three transducer design concepts for solid state applications; silicon resistor characterization at cryogenic temperatures; experimental chip mounting characterization; frequency response optimization and prototype design and fabrication. Excellent silicon sensor performance was demonstrated at liquid nitrogen temperature. A silicon resistor ion implant dose was customized for SSME temperature requirements. A basic acoustic modeling software program was developed as a design tool to evaluate frequency response characteristics.

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

NASA Technical Reports Server (NTRS)

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.

The use of the principle of superposition in measuring and predicting the thermal characteristics of an electronic equipment operated in a space environment

NASA Technical Reports Server (NTRS)

Gale, E. H.

1980-01-01

The advantages and possible pitfalls of using a generalized method of measuring and, based on these measurements, predicting the transient or steady-state thermal response characteristics of an electronic equipment designed to operate in a space environment are reviewed. The method requires generation of a set of thermal influence coefficients by test measurement in vacuo. A implified thermal mockup isused in this test. Once this data set is measured, temperatures resulting from arbitrary steady-state or time varying power profiles can be economically calculated with the aid of a digital computer.

NASA's mobile satellite communications program; ground and space segment technologies

NASA Technical Reports Server (NTRS)

Naderi, F.; Weber, W. J.; Knouse, G. H.

1984-01-01

This paper describes the Mobile Satellite Communications Program of the United States National Aeronautics and Space Administration (NASA). The program's objectives are to facilitate the deployment of the first generation commercial mobile satellite by the private sector, and to technologically enable future generations by developing advanced and high risk ground and space segment technologies. These technologies are aimed at mitigating severe shortages of spectrum, orbital slot, and spacecraft EIRP which are expected to plague the high capacity mobile satellite systems of the future. After a brief introduction of the concept of mobile satellite systems and their expected evolution, this paper outlines the critical ground and space segment technologies. Next, the Mobile Satellite Experiment (MSAT-X) is described. MSAT-X is the framework through which NASA will develop advanced ground segment technologies. An approach is outlined for the development of conformal vehicle antennas, spectrum and power-efficient speech codecs, and modulation techniques for use in the non-linear faded channels and efficient multiple access schemes. Finally, the paper concludes with a description of the current and planned NASA activities aimed at developing complex large multibeam spacecraft antennas needed for future generation mobile satellite systems.

Intracavity Rydberg-atom electromagnetically induced transparency using a high-finesse optical cavity

NASA Astrophysics Data System (ADS)

Sheng, Jiteng; Chao, Yuanxi; Kumar, Santosh; Fan, Haoquan; Sedlacek, Jonathon; Shaffer, James P.

2017-09-01

We present an experimental study of cavity-assisted Rydberg-atom electromagnetically induced transparency (EIT) using a high-finesse optical cavity (F ˜28 000 ). Rydberg atoms are excited via a two-photon transition in a ladder-type EIT configuration. A three-peak structure of the cavity transmission spectrum is observed when Rydberg EIT is generated inside the cavity. The two symmetrically spaced side peaks are caused by bright-state polaritons, while the central peak corresponds to a dark-state polariton. Anticrossing phenomena and the effects of mirror adsorbate electric fields are studied under different experimental conditions. We determine a lower bound on the coherence time for the system of 7.26 ±0.06 μ s , most likely limited by laser dephasing. The cavity-Rydberg EIT system can be useful for single-photon generation using the Rydberg blockade effect, studying many-body physics, and generating novel quantum states among many other applications.

Optimal mode transformations for linear-optical cluster-state generation

DOE PAGES

Uskov, Dmitry B.; Lougovski, Pavel; Alsing, Paul M.; ...

2015-06-15

In this paper, we analyze the generation of linear-optical cluster states (LOCSs) via sequential addition of one and two qubits. Existing approaches employ the stochastic linear-optical two-qubit controlled-Z (CZ) gate with success rate of 1/9 per operation. The question of optimality of the CZ gate with respect to LOCS generation has remained open. We report that there are alternative schemes to the CZ gate that are exponentially more efficient and show that sequential LOCS growth is indeed globally optimal. We find that the optimal cluster growth operation is a state transformation on a subspace of the full Hilbert space. Finally,more » we show that the maximal success rate of postselected entangling n photonic qubits or m Bell pairs into a cluster is (1/2) n-1 and (1/4) m-1, respectively, with no ancilla photons, and we give an explicit optical description of the optimal mode transformations.« less

Parallel Polarization State Generation

NASA Astrophysics Data System (ADS)

She, Alan; Capasso, Federico

2016-05-01

The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

Nano Goes Magnetic to Attract Big Business

NASA Technical Reports Server (NTRS)

2006-01-01

Glenn Research Center has combined state-of-the-art electrical designs with complex, computer-aided analyses to develop some of today s most advanced power systems, in space and on Earth. The center s Power and On-Board Propulsion Technology Division is the brain behind many of these power systems. For space, this division builds technologies that help power the International Space Station, the Hubble Space Telescope, and Earth-orbiting satellites. For Earth, it has woven advanced aerospace power concepts into commercial energy applications that include solar and nuclear power generation, battery and fuel cell energy storage, communications and telecommunications satellites, cryocoolers, hybrid and electric vehicles, and heating and air-conditioning systems.

Wigner functions for evanescent waves.

PubMed

Petruccelli, Jonathan C; Tian, Lei; Oh, Se Baek; Barbastathis, George

2012-09-01

We propose phase space distributions, based on an extension of the Wigner distribution function, to describe fields of any state of coherence that contain evanescent components emitted into a half-space. The evanescent components of the field are described in an optical phase space of spatial position and complex-valued angle. Behavior of these distributions upon propagation is also considered, where the rapid decay of the evanescent components is associated with the exponential decay of the associated phase space distributions. To demonstrate the structure and behavior of these distributions, we consider the fields generated from total internal reflection of a Gaussian Schell-model beam at a planar interface.

Next generation of space based sensor for application in the SSA space weather domain.

NASA Astrophysics Data System (ADS)

Jansen, Frank; Kudela, Karel; Behrens, Joerg

Next generation of space based sensor for application in the SSA space weather domain. F. Jansen1, K. Kudela2, J. Behrens1 and NESTEC consortium3 1DLR, Bremen, Germany 2IEP SAS Kosice, Slovakia 3NESTEC consortium members (DLR Bremen, DESY Hamburg, MPS Katlenburg-Lindau, CTU Prague, University of Twente, IEP-SAS Kosice, UCL/MSSL, University of Manchester, University of Surrey, Hermanus Magnetic Observatory, North-West University Potchefsroom, University of Montreal) High energy solar and galactic cosmic rays have twofold importance for the SSA space weather domain. Cosmic rays have dangerous effects for space, air and ground based assets, but on the other side cosmic rays are direct measure tools for real time space weather warning. A review of space weather related SSA results from operating global cosmic ray networks (especially those by neutron monitors and by muon directional telescopes), its limitations and main questions to be solved, is presented. Especially those recent results, received in real time and with high temporal resolution, are reviewed and discussed. In addition the relevance of these monitors and telescopes in forecasting geomagnetic disturbances are checked. Based on this study result, a next generation of highly miniaturized hybrid silicon pixel device (Medipix sensor) will be described for the following, beyond state-of-the-art application: a SSA satellite for high energy solar and galactic cosmic ray spectrum measurement, with a space plasma environment data package and CME real time imaging by means of cosmic rays. All data management and processing will be carried out on the satellite in real time. Insofar a high reduction of data and transmission to ground station of finalized space weather relevant data and images are foreseen.

Uninformative Prior Multiple Target Tracking Using Evidential Particle Filters

NASA Astrophysics Data System (ADS)

Worthy, J. L., III; Holzinger, M. J.

Space situational awareness requires the ability to initialize state estimation from short measurements and the reliable association of observations to support the characterization of the space environment. The electro-optical systems used to observe space objects cannot fully characterize the state of an object given a short, unobservable sequence of measurements. Further, it is difficult to associate these short-arc measurements if many such measurements are generated through the observation of a cluster of satellites, debris from a satellite break-up, or from spurious detections of an object. An optimization based, probabilistic short-arc observation association approach coupled with a Dempster-Shafer based evidential particle filter in a multiple target tracking framework is developed and proposed to address these problems. The optimization based approach is shown in literature to be computationally efficient and can produce probabilities of association, state estimates, and covariances while accounting for systemic errors. Rigorous application of Dempster-Shafer theory is shown to be effective at enabling ignorance to be properly accounted for in estimation by augmenting probability with belief and plausibility. The proposed multiple hypothesis framework will use a non-exclusive hypothesis formulation of Dempster-Shafer theory to assign belief mass to candidate association pairs and generate tracks based on the belief to plausibility ratio. The proposed algorithm is demonstrated using simulated observations of a GEO satellite breakup scenario.

Nuclear Thermal Propulsion for Advanced Space Exploration

NASA Technical Reports Server (NTRS)

Houts, M. G.; Borowski, S. K.; George, J. A.; Kim, T.; Emrich, W. J.; Hickman, R. R.; Broadway, J. W.; Gerrish, H. P.; Adams, R. B.

2012-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on NTP could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of the NCPS in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progress made under the NCPS project could help enable both advanced NTP and advanced Nuclear Electric Propulsion (NEP).

Individual-based models for adaptive diversification in high-dimensional phenotype spaces.

PubMed

Ispolatov, Iaroslav; Madhok, Vaibhav; Doebeli, Michael

2016-02-07

Most theories of evolutionary diversification are based on equilibrium assumptions: they are either based on optimality arguments involving static fitness landscapes, or they assume that populations first evolve to an equilibrium state before diversification occurs, as exemplified by the concept of evolutionary branching points in adaptive dynamics theory. Recent results indicate that adaptive dynamics may often not converge to equilibrium points and instead generate complicated trajectories if evolution takes place in high-dimensional phenotype spaces. Even though some analytical results on diversification in complex phenotype spaces are available, to study this problem in general we need to reconstruct individual-based models from the adaptive dynamics generating the non-equilibrium dynamics. Here we first provide a method to construct individual-based models such that they faithfully reproduce the given adaptive dynamics attractor without diversification. We then show that a propensity to diversify can be introduced by adding Gaussian competition terms that generate frequency dependence while still preserving the same adaptive dynamics. For sufficiently strong competition, the disruptive selection generated by frequency-dependence overcomes the directional evolution along the selection gradient and leads to diversification in phenotypic directions that are orthogonal to the selection gradient. Copyright © 2015 Elsevier Ltd. All rights reserved.

Human Spaceflight Safety for the Next Generation on Orbital Space Systems

NASA Technical Reports Server (NTRS)

Mango, Edward J.

2011-01-01

The National Aeronautics and Space Administration (NASA) Commercial Crew Program (CCP) has been chartered to facilitate the development of a United States (U.S.) commercial crew space transportation capability with the goal of achieving safe, reliable, and cost effective access to and from low Earth orbit (LEO) and the International Space Station (ISS) as soon as possible. Once the capability is matured and is available to the Government and other customers, NASA expects to purchase commercial services to meet its ISS crew rotation and emergency return objectives. The primary role of the CCP is to enable and ensure safe human spaceflight and processes for the next generation of earth orbital space systems. The architecture of the Program delineates the process for investment performance in safe orbital systems, Crew Transportation System (CTS) certification, and CTS Flight Readiness. A series of six technical documents build up the architecture to address the top-level CTS requirements and standards. They include Design Reference Missions, with the near term focus on ISS crew services, Certification and Service Requirements, Technical Management Processes, and Technical and Operations Standards Evaluation Processes.

Non-Gaussian quantum states generation and robust quantum non-Gaussianity via squeezing field

NASA Astrophysics Data System (ADS)

Tang, Xu-Bing; Gao, Fang; Wang, Yao-Xiong; Kuang, Sen; Shuang, Feng

2015-03-01

Recent studies show that quantum non-Gaussian states or using non-Gaussian operations can improve entanglement distillation, quantum swapping, teleportation, and cloning. In this work, employing a strategy of non-Gaussian operations (namely subtracting and adding a single photon), we propose a scheme to generate non-Gaussian quantum states named single-photon-added and -subtracted coherent (SPASC) superposition states by implementing Bell measurements, and then investigate the corresponding nonclassical features. By squeezed the input field, we demonstrate that robustness of non-Gaussianity can be improved. Controllable phase space distribution offers the possibility to approximately generate a displaced coherent superposition states (DCSS). The fidelity can reach up to F ≥ 0.98 and F ≥ 0.90 for size of amplitude z = 1.53 and 2.36, respectively. Project supported by the National Natural Science Foundation of China (Grant Nos. 61203061 and 61074052), the Outstanding Young Talent Foundation of Anhui Province, China (Grant No. 2012SQRL040), and the Natural Science Foundation of Anhui Province, China (Grant No. KJ2012Z035).

Engineering multiphoton states for linear optics computation

NASA Astrophysics Data System (ADS)

Aniello, P.; Lupo, C.; Napolitano, M.; Paris, M. G. A.

2007-03-01

Transformations achievable by linear optical components allow to generate the whole unitary group only when restricted to the one-photon subspace of a multimode Fock space. In this paper, we address the more general problem of encoding quantum information by multiphoton states, and elaborating it via ancillary extensions, linear optical passive devices and photodetection. Our scheme stems in a natural way from the mathematical structures underlying the physics of linear optical passive devices. In particular, we analyze an economical procedure for mapping a fiducial 2-photon 2-mode state into an arbitrary 2-photon 2-mode state using ancillary resources and linear optical passive N-ports assisted by post-selection. We found that adding a single ancilla mode is enough to generate any desired target state. The effect of imperfect photodetection in post-selection is considered and a simple trade-off between success probability and fidelity is derived.

Many-body instabilities and mass generation in slow Dirac materials

NASA Astrophysics Data System (ADS)

Triola, Christopher; Zhu, Jian-Xin; Migliori, Albert; Balatsky, Alexander V.

2015-07-01

Some Kondo insulators are expected to possess topologically protected surface states with linear Dirac spectrum: the topological Kondo insulators. Because the bulk states of these systems typically have heavy effective electron masses, the surface states may exhibit extraordinarily small Fermi velocities that could force the effective fine structure constant of the surface states into the strong coupling regime. Using a tight-binding model, we study the many-body instabilities of these systems and identify regions of parameter space in which the system exhibits spin density wave and charge density wave order.

DYGABCD: A program for calculating linear A, B, C, and D matrices from a nonlinear dynamic engine simulation

NASA Technical Reports Server (NTRS)

Geyser, L. C.

1978-01-01

A digital computer program, DYGABCD, was developed that generates linearized, dynamic models of simulated turbofan and turbojet engines. DYGABCD is based on an earlier computer program, DYNGEN, that is capable of calculating simulated nonlinear steady-state and transient performance of one- and two-spool turbojet engines or two- and three-spool turbofan engines. Most control design techniques require linear system descriptions. For multiple-input/multiple-output systems such as turbine engines, state space matrix descriptions of the system are often desirable. DYGABCD computes the state space matrices commonly referred to as the A, B, C, and D matrices required for a linear system description. The report discusses the analytical approach and provides a users manual, FORTRAN listings, and a sample case.

Discrete Wigner formalism for qubits and noncontextuality of Clifford gates on qubit stabilizer states

NASA Astrophysics Data System (ADS)

Kocia, Lucas; Love, Peter

2017-12-01

We show that qubit stabilizer states can be represented by non-negative quasiprobability distributions associated with a Wigner-Weyl-Moyal formalism where Clifford gates are positive state-independent maps. This is accomplished by generalizing the Wigner-Weyl-Moyal formalism to three generators instead of two—producing an exterior, or Grassmann, algebra—which results in Clifford group gates for qubits that act as a permutation on the finite Weyl phase space points naturally associated with stabilizer states. As a result, a non-negative probability distribution can be associated with each stabilizer state's three-generator Wigner function, and these distributions evolve deterministically to one another under Clifford gates. This corresponds to a hidden variable theory that is noncontextual and local for qubit Clifford gates while Clifford (Pauli) measurements have a context-dependent representation. Equivalently, we show that qubit Clifford gates can be expressed as propagators within the three-generator Wigner-Weyl-Moyal formalism whose semiclassical expansion is truncated at order ℏ0 with a finite number of terms. The T gate, which extends the Clifford gate set to one capable of universal quantum computation, requires a semiclassical expansion of the propagator to order ℏ1. We compare this approach to previous quasiprobability descriptions of qubits that relied on the two-generator Wigner-Weyl-Moyal formalism and find that the two-generator Weyl symbols of stabilizer states result in a description of evolution under Clifford gates that is state-dependent, in contrast to the three-generator formalism. We have thus extended Wigner non-negative quasiprobability distributions from the odd d -dimensional case to d =2 qubits, which describe the noncontextuality of Clifford gates and contextuality of Pauli measurements on qubit stabilizer states.

A new state space model for the NASA/JPL 70-meter antenna servo controls

NASA Technical Reports Server (NTRS)

Hill, R. E.

1987-01-01

A control axis referenced model of the NASA/JPL 70-m antenna structure is combined with the dynamic equations of servo components to produce a comprehansive state variable (matrix) model of the coupled system. An interactive Fortran program for generating the linear system model and computing its salient parameters is described. Results are produced in a state variable, block diagram, and in factored transfer function forms to facilitate design and analysis by classical as well as modern control methods.

Task-specific stability in muscle activation space during unintentional movements.

PubMed

Falaki, Ali; Towhidkhah, Farzad; Zhou, Tao; Latash, Mark L

2014-11-01

We used robot-generated perturbations applied during position-holding tasks to explore stability of induced unintentional movements in a multidimensional space of muscle activations. Healthy subjects held the handle of a robot against a constant bias force and were instructed not to interfere with hand movements produced by changes in the external force. Transient force changes were applied leading to handle displacement away from the initial position and then back toward the initial position. Intertrial variance in the space of muscle modes (eigenvectors in the muscle activations space) was quantified within two subspaces, corresponding to unchanged handle coordinate and to changes in the handle coordinate. Most variance was confined to the former subspace in each of the three phases of movement, the initial steady state, the intermediate position, and the final steady state. The same result was found when the changes in muscle activation were analyzed between the initial and final steady states. Changes in the dwell time between the perturbation force application and removal led to different final hand locations undershooting the initial position. The magnitude of the undershot scaled with the dwell time, while the structure of variance in the muscle activation space did not depend on the dwell time. We conclude that stability of the hand coordinate is ensured during both intentional and unintentional actions via similar mechanisms. Relative equifinality in the external space after transient perturbations may be associated with varying states in the redundant space of muscle activations. The results fit a hierarchical scheme for the control of voluntary movements with referent configurations and redundant mapping between the levels of the hierarchy.

A clustering-based graph Laplacian framework for value function approximation in reinforcement learning.

PubMed

Xu, Xin; Huang, Zhenhua; Graves, Daniel; Pedrycz, Witold

2014-12-01

In order to deal with the sequential decision problems with large or continuous state spaces, feature representation and function approximation have been a major research topic in reinforcement learning (RL). In this paper, a clustering-based graph Laplacian framework is presented for feature representation and value function approximation (VFA) in RL. By making use of clustering-based techniques, that is, K-means clustering or fuzzy C-means clustering, a graph Laplacian is constructed by subsampling in Markov decision processes (MDPs) with continuous state spaces. The basis functions for VFA can be automatically generated from spectral analysis of the graph Laplacian. The clustering-based graph Laplacian is integrated with a class of approximation policy iteration algorithms called representation policy iteration (RPI) for RL in MDPs with continuous state spaces. Simulation and experimental results show that, compared with previous RPI methods, the proposed approach needs fewer sample points to compute an efficient set of basis functions and the learning control performance can be improved for a variety of parameter settings.

Analytical Tools for Space Suit Design

NASA Technical Reports Server (NTRS)

Aitchison, Lindsay

2011-01-01

As indicated by the implementation of multiple small project teams within the agency, NASA is adopting a lean approach to hardware development that emphasizes quick product realization and rapid response to shifting program and agency goals. Over the past two decades, space suit design has been evolutionary in approach with emphasis on building prototypes then testing with the largest practical range of subjects possible. The results of these efforts show continuous improvement but make scaled design and performance predictions almost impossible with limited budgets and little time. Thus, in an effort to start changing the way NASA approaches space suit design and analysis, the Advanced Space Suit group has initiated the development of an integrated design and analysis tool. It is a multi-year-if not decadal-development effort that, when fully implemented, is envisioned to generate analysis of any given space suit architecture or, conversely, predictions of ideal space suit architectures given specific mission parameters. The master tool will exchange information to and from a set of five sub-tool groups in order to generate the desired output. The basic functions of each sub-tool group, the initial relationships between the sub-tools, and a comparison to state of the art software and tools are discussed.

Photonics

NASA Technical Reports Server (NTRS)

1991-01-01

Optoelectronic materials and devices are examined. Optoelectronic devices, which generate, detect, modulate, or switch electromagnetic radiation are being developed for a variety of space applications. The program includes spatial light modulators, solid state lasers, optoelectronic integrated circuits, nonlinear optical materials and devices, fiber optics, and optical networking photovoltaic technology and optical processing.

Dynamical generation of noiseless quantum subsystems

PubMed

Viola; Knill; Lloyd

2000-10-16

We combine dynamical decoupling and universal control methods for open quantum systems with coding procedures. By exploiting a general algebraic approach, we show how appropriate encodings of quantum states result in obtaining universal control over dynamically generated noise-protected subsystems with limited control resources. In particular, we provide a constructive scheme based on two-body Hamiltonians for performing universal quantum computation over large noiseless spaces which can be engineered in the presence of arbitrary linear quantum noise.

Efficient Transition Probability Computation for Continuous-Time Branching Processes via Compressed Sensing.

PubMed

Xu, Jason; Minin, Vladimir N

2015-07-01

Branching processes are a class of continuous-time Markov chains (CTMCs) with ubiquitous applications. A general difficulty in statistical inference under partially observed CTMC models arises in computing transition probabilities when the discrete state space is large or uncountable. Classical methods such as matrix exponentiation are infeasible for large or countably infinite state spaces, and sampling-based alternatives are computationally intensive, requiring integration over all possible hidden events. Recent work has successfully applied generating function techniques to computing transition probabilities for linear multi-type branching processes. While these techniques often require significantly fewer computations than matrix exponentiation, they also become prohibitive in applications with large populations. We propose a compressed sensing framework that significantly accelerates the generating function method, decreasing computational cost up to a logarithmic factor by only assuming the probability mass of transitions is sparse. We demonstrate accurate and efficient transition probability computations in branching process models for blood cell formation and evolution of self-replicating transposable elements in bacterial genomes.

NASA funding opportunities for optical fabrication and testing technology development

NASA Astrophysics Data System (ADS)

Stahl, H. Philip

2013-09-01

NASA requires technologies to fabricate and test optical components to accomplish its highest priority science missions. The NRC ASTRO2010 Decadal Survey states that an advanced large-aperture UVOIR telescope is required to enable the next generation of compelling astrophysics and exo-planet science; and, that present technology is not mature enough to affordably build and launch any potential UVOIR mission concept. The NRC 2012 NASA Space Technology Roadmaps and Priorities Report states that the highest priority technology in which NASA should invest to `Expand our understanding of Earth and the universe' is next generation X-ray and UVOIR telescopes. Each of the Astrophysics division Program Office Annual Technology Reports (PATR) identifies specific technology needs. NASA has a variety of programs to fund enabling technology development: SBIR (Small Business Innovative Research); the ROSES APRA and SAT programs (Research Opportunities in Space and Earth Science; Astrophysics Research and Analysis program; Strategic Astrophysics Technology program); and several Office of the Chief Technologist (OCT) programs.

NASA Funding Opportunities for Optical Fabrication and Testing Technology Development

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2013-01-01

NASA requires technologies to fabricate and test optical components to accomplish its highest priority science missions. The NRC ASTRO2010 Decadal Survey states that an advanced large-aperture UVOIR telescope is required to enable the next generation of compelling astrophysics and exo-planet science; and, that present technology is not mature enough to affordably build and launch any potential UVOIR mission concept. The NRC 2012 NASA Space Technology Roadmaps and Priorities Report states that the highest priority technology in which NASA should invest to 'Expand our understanding of Earth and the universe' is next generation X-ray and UVOIR telescopes. Each of the Astrophysics division Program Office Annual Technology Reports (PATR) identifies specific technology needs. NASA has a variety of programs to fund enabling technology development: SBIR (Small Business Innovative Research); the ROSES APRA and SAT programs (Research Opportunities in Space and Earth Science; Astrophysics Research and Analysis program; Strategic Astrophysics Technology program); and several Office of the Chief Technologist (OCT) programs

Efficient Transition Probability Computation for Continuous-Time Branching Processes via Compressed Sensing

PubMed Central

Xu, Jason; Minin, Vladimir N.

2016-01-01

Branching processes are a class of continuous-time Markov chains (CTMCs) with ubiquitous applications. A general difficulty in statistical inference under partially observed CTMC models arises in computing transition probabilities when the discrete state space is large or uncountable. Classical methods such as matrix exponentiation are infeasible for large or countably infinite state spaces, and sampling-based alternatives are computationally intensive, requiring integration over all possible hidden events. Recent work has successfully applied generating function techniques to computing transition probabilities for linear multi-type branching processes. While these techniques often require significantly fewer computations than matrix exponentiation, they also become prohibitive in applications with large populations. We propose a compressed sensing framework that significantly accelerates the generating function method, decreasing computational cost up to a logarithmic factor by only assuming the probability mass of transitions is sparse. We demonstrate accurate and efficient transition probability computations in branching process models for blood cell formation and evolution of self-replicating transposable elements in bacterial genomes. PMID:26949377

NASA Funding Opportunities for Optical Fabrication and Testing Technology Development

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2013-01-01

Technologies to fabricate and test optical components are required for NASA to accomplish its highest priority science missions. For example, the NRC ASTRO2010 Decadal Survey states that an advanced large-aperture UVOIR telescope is required to enable the next generation of compelling astrophysics and exo-planet science; and that present technology is not mature enough to affordably build and launch any potential UVOIR mission concept. The NRC 2012 NASA Space Technology Roadmaps and Priorities report states that the highest priority technology in which NASA should invest to 'Expand our understanding of Earth and the universe' is a new generation of astronomical telescopes. And, each of the Astrophysics division Program Office Annual Technology Reports (PATR), identifies specific technology needs. NASA has a variety of programs to fund enabling technology development: SBIR (Small Business Innovative Research); the ROSES APRA and SAT programs (Research Opportunities in Space and Earth Science; Astrophysics Research and Analysis program; Strategic Astrophysics Technology program); and several Office of the Chief Technologist (OCT) technology development programs.

Total-dose radiation effects data for semiconductor devices. 1985 Supplement. Volume 2, part B

NASA Technical Reports Server (NTRS)

Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

1986-01-01

Steady-state, total-dose radiation test data are provided in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. The document is in two volumes: Volume 1 provides data on diodes, bipolar transistors, field effect transistors, and miscellaneous semiconductor types, and Volume 2 (Parts A and B) provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done steady-state 2.5-MeV electron beam. However, some radiation exposures were made with a Cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose. All data were generated in support of NASA space programs by the JPL Radiation Effects and Testing Group (514).

Hybrid Power Management Program Continued

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.

2002-01-01

Hybrid Power Management (HPM) is the innovative integration of diverse, state-of-the-art power devices in an optimal configuration for space and terrestrial applications. The appropriate application and control of the various power devices significantly improves overall system performance and efficiency. The advanced power devices include ultracapacitors and photovoltaics. HPM has extremely wide potential with applications including power-generation, transportation, biotechnology, and space power systems. It may significantly alleviate global energy concerns, improve the environment, and stimulate the economy.

International Conference on Optical Computing Held in Edinburgh, Scotland on August 22-25, 1994. Technical Digest

DTIC Science & Technology

1994-08-24

Kusuda, T. Kishimoto and Y. Mitsuhashi, Nippon Sheet Glass Co. Ltd., lbaraki, Japan. A vertical and horizontal integration technique of free-space...transparent electrode on a piece of cover glass drives the liquid crystal into the desired state. Data are transferred to the SLM over 32 parallel...shows that the shift registers and clock generation circuits function as designed. A cover- glass was fixed over the pixel array, spaced with polyimide

Baryon spectrum from superconformal quantum mechanics and its light-front holographic embedding

DOE PAGES

de Teramond, Guy F.; Dosch, Hans Gunter; Brodsky, Stanley J.

2015-02-27

We describe the observed light-baryon spectrum by extending superconformal quantum mechanics to the light front and its embedding in AdS space. This procedure uniquely determines the confinement potential for arbitrary half-integer spin. To this end, we show that fermionic wave equations in AdS space are dual to light-front supersymmetric quantum-mechanical bound-state equations in physical space-time. The specific breaking of conformal invariance explains hadronic properties common to light mesons and baryons, such as the observed mass pattern in the radial and orbital excitations, from the spectrum generating algebra. Lastly, the holographic embedding in AdS also explains distinctive and systematic features, suchmore » as the spin-J degeneracy for states with the same orbital angular momentum, observed in the light-baryon spectrum.« less

COI Structural Analysis Presentation

NASA Technical Reports Server (NTRS)

Cline, Todd; Stahl, H. Philip (Technical Monitor)

2001-01-01

This report discusses the structural analysis of the Next Generation Space Telescope Mirror System Demonstrator (NMSD) developed by Composite Optics Incorporated (COI) in support of the Next Generation Space Telescope (NGST) project. The mirror was submitted to Marshall Space Flight Center (MSFC) for cryogenic testing and evaluation. Once at MSFC, the mirror was lowered to approximately 40 K and the optical surface distortions were measured. Alongside this experiment, an analytical model was developed and used to compare to the test results. A NASTRAN finite element model was provided by COI and a thermal model was developed from it. Using the thermal model, steady state nodal temperatures were calculated based on the predicted environment of the large cryogenic test chamber at MSFC. This temperature distribution was applied in the structural analysis to solve for the deflections of the optical surface. Finally, these deflections were submitted for optical analysis and comparison to the interferometer test data.

Iterative tailoring of optical quantum states with homodyne measurements.

PubMed

Etesse, Jean; Kanseri, Bhaskar; Tualle-Brouri, Rosa

2014-12-01

As they can travel long distances, free space optical quantum states are good candidates for carrying information in quantum information technology protocols. These states, however, are often complex to produce and require protocols whose success probability drops quickly with an increase of the mean photon number. Here we propose a new protocol for the generation and growth of arbitrary states, based on one by one coherent adjunctions of the simple state superposition α|0〉 + β|1〉. Due to the nature of the protocol, which allows for the use of quantum memories, it can lead to high performances.

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

NASA Technical Reports Server (NTRS)

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.

Controlling quantum interference in phase space with amplitude.

PubMed

Xue, Yinghong; Li, Tingyu; Kasai, Katsuyuki; Okada-Shudo, Yoshiko; Watanabe, Masayoshi; Zhang, Yun

2017-05-23

We experimentally show a quantum interference in phase space by interrogating photon number probabilities (n = 2, 3, and 4) of a displaced squeezed state, which is generated by an optical parametric amplifier and whose displacement is controlled by amplitude of injected coherent light. It is found that the probabilities exhibit oscillations of interference effect depending upon the amplitude of the controlling light field. This phenomenon is attributed to quantum interference in phase space and indicates the capability of controlling quantum interference using amplitude. This remarkably contrasts with the oscillations of interference effects being usually controlled by relative phase in classical optics.

What is the Value of Space Exploration? A Prairie Perspective

NASA Technical Reports Server (NTRS)

1995-01-01

Within the span of a single generation the purpose, form and mission of the United States civil space program has changed radically. Demonstrating technological superiority through a lunar landing has given way to an, as yet unclear agenda. Although hazy, the rough features of a 21st century program are discernable: it must be cost effective; economically, as well as, politically driven; and, international. Less clear are the missions. Will they include human habitation of cislunar space and the solar system? Earth observations? Planetary discovery? A Mars settlement? Perhaps, some of each? And if so, in what balance?

Langley aeronautics and space test highlights, 1984

NASA Technical Reports Server (NTRS)

1984-01-01

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Some of the significant tests which were performed during calendar year 1984 in Langley test facilities are highlighted. The broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research are illustrated.

Nebula: reconstruction and visualization of scattering data in reciprocal space.

PubMed

Reiten, Andreas; Chernyshov, Dmitry; Mathiesen, Ragnvald H

2015-04-01

Two-dimensional solid-state X-ray detectors can now operate at considerable data throughput rates that allow full three-dimensional sampling of scattering data from extended volumes of reciprocal space within second to minute time-scales. For such experiments, simultaneous analysis and visualization allows for remeasurements and a more dynamic measurement strategy. A new software, Nebula , is presented. It efficiently reconstructs X-ray scattering data, generates three-dimensional reciprocal space data sets that can be visualized interactively, and aims to enable real-time processing in high-throughput measurements by employing parallel computing on commodity hardware.

Nebula: reconstruction and visualization of scattering data in reciprocal space

PubMed Central

Reiten, Andreas; Chernyshov, Dmitry; Mathiesen, Ragnvald H.

2015-01-01

Two-dimensional solid-state X-ray detectors can now operate at considerable data throughput rates that allow full three-dimensional sampling of scattering data from extended volumes of reciprocal space within second to minute time­scales. For such experiments, simultaneous analysis and visualization allows for remeasurements and a more dynamic measurement strategy. A new software, Nebula, is presented. It efficiently reconstructs X-ray scattering data, generates three-dimensional reciprocal space data sets that can be visualized interactively, and aims to enable real-time processing in high-throughput measurements by employing parallel computing on commodity hardware. PMID:25844083

Elementary Kaluza-Klein towers revisited

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

Grard, Fernand; Nuyts, Jean

2006-12-15

Considering that the momentum squared in the extra dimensions is the physically relevant quantity for the generation of the Kaluza-Klein mass states, we have reanalyzed mathematically the procedure for five dimensional scalar fields within the Arkhani-Ahmed, Dimopoulos and Dvali scenario. We find new sets of physically allowed boundary conditions. Beside the usual results, they lead to new towers with non regular mass spacing, to lonely mass states and to tachyons.

Compensated Crystal Assemblies for Type-II Entangled Photon Generation in Quantum Cluster States

DTIC Science & Technology

2010-03-01

in quantum computational architectures that operate by principles entirely distinct from any based on classical physics. In contrast with other...of the SPDC spectral function, to enable applications in regions that have not been accessible with other methods. Quantum Information and Computation ...Eliminating frequency and space-time correlations in multi-photon states, PRA 64, 063815, 2001 [2]A. Zeilinger et.al. Experimental One-way computing

Final Report from The University of Texas at Austin for DEGAS: Dynamic Global Address Space programming environments

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

Erez, Mattan; Yelick, Katherine; Sarkar, Vivek

The Dynamic, Exascale Global Address Space programming environment (DEGAS) project will develop the next generation of programming models and runtime systems to meet the challenges of Exascale computing. Our approach is to provide an efficient and scalable programming model that can be adapted to application needs through the use of dynamic runtime features and domain-specific languages for computational kernels. We address the following technical challenges: Programmability: Rich set of programming constructs based on a Hierarchical Partitioned Global Address Space (HPGAS) model, demonstrated in UPC++. Scalability: Hierarchical locality control, lightweight communication (extended GASNet), and ef- ficient synchronization mechanisms (Phasers). Performance Portability:more » Just-in-time specialization (SEJITS) for generating hardware-specific code and scheduling libraries for domain-specific adaptive runtimes (Habanero). Energy Efficiency: Communication-optimal code generation to optimize energy efficiency by re- ducing data movement. Resilience: Containment Domains for flexible, domain-specific resilience, using state capture mechanisms and lightweight, asynchronous recovery mechanisms. Interoperability: Runtime and language interoperability with MPI and OpenMP to encourage broad adoption.« less

Four-body trajectory optimization

NASA Technical Reports Server (NTRS)

Pu, C. L.; Edelbaum, T. N.

1974-01-01

A comprehensive optimization program has been developed for computing fuel-optimal trajectories between the earth and a point in the sun-earth-moon system. It presents methods for generating fuel optimal two-impulse trajectories which may originate at the earth or a point in space and fuel optimal three-impulse trajectories between two points in space. The extrapolation of the state vector and the computation of the state transition matrix are accomplished by the Stumpff-Weiss method. The cost and constraint gradients are computed analytically in terms of the terminal state and the state transition matrix. The 4-body Lambert problem is solved by using the Newton-Raphson method. An accelerated gradient projection method is used to optimize a 2-impulse trajectory with terminal constraint. The Davidon's Variance Method is used both in the accelerated gradient projection method and the outer loop of a 3-impulse trajectory optimization problem.

A Machine-Checked Proof of A State-Space Construction Algorithm

NASA Technical Reports Server (NTRS)

Catano, Nestor; Siminiceanu, Radu I.

2010-01-01

This paper presents the correctness proof of Saturation, an algorithm for generating state spaces of concurrent systems, implemented in the SMART tool. Unlike the Breadth First Search exploration algorithm, which is easy to understand and formalise, Saturation is a complex algorithm, employing a mutually-recursive pair of procedures that compute a series of non-trivial, nested local fixed points, corresponding to a chaotic fixed point strategy. A pencil-and-paper proof of Saturation exists, but a machine checked proof had never been attempted. The key element of the proof is the characterisation theorem of saturated nodes in decision diagrams, stating that a saturated node represents a set of states encoding a local fixed-point with respect to firing all events affecting only the node s level and levels below. For our purpose, we have employed the Prototype Verification System (PVS) for formalising the Saturation algorithm, its data structures, and for conducting the proofs.

Computing the modal mass from the state space model in combined experimental-operational modal analysis

NASA Astrophysics Data System (ADS)

Cara, Javier

2016-05-01

Modal parameters comprise natural frequencies, damping ratios, modal vectors and modal masses. In a theoretic framework, these parameters are the basis for the solution of vibration problems using the theory of modal superposition. In practice, they can be computed from input-output vibration data: the usual procedure is to estimate a mathematical model from the data and then to compute the modal parameters from the estimated model. The most popular models for input-output data are based on the frequency response function, but in recent years the state space model in the time domain has become popular among researchers and practitioners of modal analysis with experimental data. In this work, the equations to compute the modal parameters from the state space model when input and output data are available (like in combined experimental-operational modal analysis) are derived in detail using invariants of the state space model: the equations needed to compute natural frequencies, damping ratios and modal vectors are well known in the operational modal analysis framework, but the equation needed to compute the modal masses has not generated much interest in technical literature. These equations are applied to both a numerical simulation and an experimental study in the last part of the work.

Protein folding: complex potential for the driving force in a two-dimensional space of collective variables.

PubMed

Chekmarev, Sergei F

2013-10-14

Using the Helmholtz decomposition of the vector field of folding fluxes in a two-dimensional space of collective variables, a potential of the driving force for protein folding is introduced. The potential has two components. One component is responsible for the source and sink of the folding flows, which represent respectively, the unfolded states and the native state of the protein, and the other, which accounts for the flow vorticity inherently generated at the periphery of the flow field, is responsible for the canalization of the flow between the source and sink. The theoretical consideration is illustrated by calculations for a model β-hairpin protein.

A Game-Theoretic Approach to Branching Time Abstract-Check-Refine Process

NASA Technical Reports Server (NTRS)

Wang, Yi; Tamai, Tetsuo

2009-01-01

Since the complexity of software systems continues to grow, most engineers face two serious problems: the state space explosion problem and the problem of how to debug systems. In this paper, we propose a game-theoretic approach to full branching time model checking on three-valued semantics. The three-valued models and logics provide successful abstraction that overcomes the state space explosion problem. The game style model checking that generates counter-examples can guide refinement or identify validated formulas, which solves the system debugging problem. Furthermore, output of our game style method will give significant information to engineers in detecting where errors have occurred and what the causes of the errors are.

Using Models to Enhance Exposure Characterization for Air Pollution Health Studies

EPA Science Inventory

The United States and the United Kingdom are faced with increasing challenges in determining the human health impact of air pollutants emitted locally. Often, these pollutants can be toxic at relatively low doses, are highly reactive, or generate large gradients across space beca...

Spinoff 1986.

ERIC Educational Resources Information Center

Haggerty, James J.

The National Aeronautics and Space Administration (NASA) seeks to broaden and accelerate use of their technical knowledge. This publication is intended to heighten public awareness of the technology available for use and its potential for economic and social benefit to the United States. Section 1 outlines NASA's mainline efforts that generate new…

Use of Crystal Structure Informatics for Defining the Conformational Space Needed for Predicting Crystal Structures of Pharmaceutical Molecules.

PubMed

Iuzzolino, Luca; Reilly, Anthony M; McCabe, Patrick; Price, Sarah L

2017-10-10

Determining the range of conformations that a flexible pharmaceutical-like molecule could plausibly adopt in a crystal structure is a key to successful crystal structure prediction (CSP) studies. We aim to use conformational information from the crystal structures in the Cambridge Structural Database (CSD) to facilitate this task. The conformations produced by the CSD Conformer Generator are reduced in number by considering the underlying rotamer distributions, an analysis of changes in molecular shape, and a minimal number of molecular ab initio calculations. This method is tested for five pharmaceutical-like molecules where an extensive CSP study has already been performed. The CSD informatics-derived set of crystal structure searches generates almost all the low-energy crystal structures previously found, including all experimental structures. The workflow effectively combines information on individual torsion angles and then eliminates the combinations that are too high in energy to be found in the solid state, reducing the resources needed to cover the solid-state conformational space of a molecule. This provides insights into how the low-energy solid-state and isolated-molecule conformations are related to the properties of the individual flexible torsion angles.

Efficiency arcjet thruster with controlled arc startup and steady state attachment

NASA Technical Reports Server (NTRS)

Smith, William W. (Inventor); Knowles, Steven C. (Inventor)

1989-01-01

An improved efficiency arcjet thruster has a constrictor and electrically-conductive nozzle anode defining an arc chamber, and an electrically-conductive rod having a tip spaced upstream from the constrictor and defining a cathode spaced from the anode by a gap generally coextensive with the arc chamber. An electrical potential is applied to the anode and cathode to generate an electrical arc in the arc chamber from the cathode to anode. Catalytically decomposed hydrazine is supplied to the arc chamber with generation of the arc so as to produce thermal heating and expansion thereof through the nozzle. The constrictor can have a electrically insulative portion disposed between the cathode tip and the nozzle anode, and an electrically-conductive anode extension disposed along the insulative portion so as to define an auxiliary gap with the cathode tip substantially smaller than the gap defined between the cathode and nozzle anode for facilitating startup of arc generation. The constrictor can also include an electrically-conductive electrode with a variable electrical potential to vary the shape of the arc generated in the arc chamber. Also, the cathode is mounted for axial movement such that the gap between its tip and the nozzle anode can be varied to facilitate a generally nonerosive generation of the electrical arc at startup and reliable steady state operation. Further, the arc chamber can have a nonparallel subsonic-to-supersonic transition configuration, or alternatively solely a nonparallel supersonic configuration, for improved arc attachment.

State of the Data Union, 1992

NASA Technical Reports Server (NTRS)

1992-01-01

This is the first report on the State of the Data Union (SDU) for the NASA Office of Space Science and Applications (OSSA). OSSA responsibilities include the collection, analysis, and permanent archival of data critical to space science research. The nature of how this is done by OSSA is evolving to keep pace with changes in space research. Current and planned missions have evolved to be more complex and multidisciplinary, and are generating much more data and lasting longer than earlier missions. New technologies enable global access to data, transfer of huge volumes of data, and increasingly complex analysis. The SDU provides a snapshot of this dynamic environment, identifying trends in capabilities and requirements. The current space science data environment is described and parameters which capture the pulse of key functions within that environment are presented. Continuous efforts of OSSA to improve the availability and quality of data provided to the scientific community are reported, highlighting efforts such as the Data Management Initiative.

Scalable approximate policies for Markov decision process models of hospital elective admissions.

PubMed

Zhu, George; Lizotte, Dan; Hoey, Jesse

2014-05-01

To demonstrate the feasibility of using stochastic simulation methods for the solution of a large-scale Markov decision process model of on-line patient admissions scheduling. The problem of admissions scheduling is modeled as a Markov decision process in which the states represent numbers of patients using each of a number of resources. We investigate current state-of-the-art real time planning methods to compute solutions to this Markov decision process. Due to the complexity of the model, traditional model-based planners are limited in scalability since they require an explicit enumeration of the model dynamics. To overcome this challenge, we apply sample-based planners along with efficient simulation techniques that given an initial start state, generate an action on-demand while avoiding portions of the model that are irrelevant to the start state. We also propose a novel variant of a popular sample-based planner that is particularly well suited to the elective admissions problem. Results show that the stochastic simulation methods allow for the problem size to be scaled by a factor of almost 10 in the action space, and exponentially in the state space. We have demonstrated our approach on a problem with 81 actions, four specialities and four treatment patterns, and shown that we can generate solutions that are near-optimal in about 100s. Sample-based planners are a viable alternative to state-based planners for large Markov decision process models of elective admissions scheduling. Copyright © 2014 Elsevier B.V. All rights reserved.

Space shuttle electrical power generation and reactant supply system

NASA Technical Reports Server (NTRS)

Simon, W. E.

1985-01-01

The design philosophy and development experience of fuel cell power generation and cryogenic reactant supply systems are reviewed, beginning with the state of technology at the conclusion of the Apollo Program. Technology advancements span a period of 10 years from initial definition phase to the most recent space transportation system (STS) flights. The development program encompassed prototype, verification, and qualification hardware, as well as post-STS-1 design improvements. Focus is on the problems encountered, the scientific and engineering approaches employed to meet the technological challenges, and the results obtained. Major technology barriers are discussed, and the evolving technology development paths are traced from their conceptual beginnings to the fully man-rated systems which are now an integral part of the shuttle vehicle.

Space Station-Baseline Configuration

NASA Technical Reports Server (NTRS)

1989-01-01

In response to President Reagan's directive to NASA to develop a permanent marned Space Station within a decade, part of the State of the Union message to Congress on January 25, 1984, NASA and the Administration adopted a phased approach to Station development. This approach provided an initial capability at reduced costs, to be followed by an enhanced Space Station capability in the future. This illustration depicts the baseline configuration, which features a 110-meter-long horizontal boom with four pressurized modules attached in the middle. Located at each end are four photovoltaic arrays generating a total of 75-kW of power. Two attachment points for external payloads are provided along this boom. The four pressurized modules include the following: A laboratory and habitation module provided by the United States; two additional laboratories, one each provided by the European Space Agency (ESA) and Japan; and an ESA-provided Man-Tended Free Flyer, a pressurized module capable of operations both attached to and separate from the Space Station core. Canada was expected to provide the first increment of a Mobile Serving System.

Space Station-Baseline Configuration With Callouts

NASA Technical Reports Server (NTRS)

1989-01-01

In response to President Reagan's directive to NASA to develop a permanent marned Space Station within a decade, part of the State of the Union message to Congress on January 25, 1984, NASA and the Administration adopted a phased approach to Station development. This approach provided an initial capability at reduced costs, to be followed by an enhanced Space Station capability in the future. This illustration depicts the baseline configuration, which features a 110-meter-long horizontal boom with four pressurized modules attached in the middle. Located at each end are four photovoltaic arrays generating a total of 75-kW of power. Two attachment points for external payloads are provided along this boom. The four pressurized modules include the following: A laboratory and habitation module provided by the United States; two additional laboratories, one each provided by the European Space Agency (ESA) and Japan; and an ESA-provided Man-Tended Free Flyer, a pressurized module capable of operations both attached to and separate from the Space Station core. Canada was expected to provide the first increment of a Mobile Serving System.

Space Station

NASA Image and Video Library

1989-08-01

In response to President Reagan's directive to NASA to develop a permanent marned Space Station within a decade, part of the State of the Union message to Congress on January 25, 1984, NASA and the Administration adopted a phased approach to Station development. This approach provided an initial capability at reduced costs, to be followed by an enhanced Space Station capability in the future. This illustration depicts the baseline configuration, which features a 110-meter-long horizontal boom with four pressurized modules attached in the middle. Located at each end are four photovoltaic arrays generating a total of 75-kW of power. Two attachment points for external payloads are provided along this boom. The four pressurized modules include the following: A laboratory and habitation module provided by the United States; two additional laboratories, one each provided by the European Space Agency (ESA) and Japan; and an ESA-provided Man-Tended Free Flyer, a pressurized module capable of operations both attached to and separate from the Space Station core. Canada was expected to provide the first increment of a Mobile Serving System.

Multilevel perspective on high-order harmonic generation in solids

NASA Astrophysics Data System (ADS)

Wu, Mengxi; Browne, Dana A.; Schafer, Kenneth J.; Gaarde, Mette B.

2016-12-01

We investigate high-order harmonic generation in a solid, modeled as a multilevel system dressed by a strong infrared laser field. We show that the cutoff energies and the relative strengths of the multiple plateaus that emerge in the harmonic spectrum can be understood both qualitatively and quantitatively by considering a combination of adiabatic and diabatic processes driven by the strong field. Such a model was recently used to interpret the multiple plateaus exhibited in harmonic spectra generated by solid argon and krypton [G. Ndabashimiye et al., Nature 534, 520 (2016), 10.1038/nature17660]. We also show that when the multilevel system originates from the Bloch state at the Γ point of the band structure, the laser-dressed states are equivalent to the Houston states [J. B. Krieger and G. J. Iafrate, Phys. Rev. B 33, 5494 (1986), 10.1103/PhysRevB.33.5494] and will therefore map out the band structure away from the Γ point as the laser field increases. This leads to a semiclassical three-step picture in momentum space that describes the high-order harmonic generation process in a solid.

On the mixing time in the Wang-Landau algorithm

NASA Astrophysics Data System (ADS)

Fadeeva, Marina; Shchur, Lev

2018-01-01

We present preliminary results of the investigation of the properties of the Markov random walk in the energy space generated by the Wang-Landau probability. We build transition matrix in the energy space (TMES) using the exact density of states for one-dimensional and two-dimensional Ising models. The spectral gap of TMES is inversely proportional to the mixing time of the Markov chain. We estimate numerically the dependence of the mixing time on the lattice size, and extract the mixing exponent.

Stomach-brain synchrony reveals a novel, delayed-connectivity resting-state network in humans

PubMed Central

Devauchelle, Anne-Dominique; Béranger, Benoît; Tallon-Baudry, Catherine

2018-01-01

Resting-state networks offer a unique window into the brain’s functional architecture, but their characterization remains limited to instantaneous connectivity thus far. Here, we describe a novel resting-state network based on the delayed connectivity between the brain and the slow electrical rhythm (0.05 Hz) generated in the stomach. The gastric network cuts across classical resting-state networks with partial overlap with autonomic regulation areas. This network is composed of regions with convergent functional properties involved in mapping bodily space through touch, action or vision, as well as mapping external space in bodily coordinates. The network is characterized by a precise temporal sequence of activations within a gastric cycle, beginning with somato-motor cortices and ending with the extrastriate body area and dorsal precuneus. Our results demonstrate that canonical resting-state networks based on instantaneous connectivity represent only one of the possible partitions of the brain into coherent networks based on temporal dynamics. PMID:29561263

Planning with Continuous Resources in Stochastic Domains

NASA Technical Reports Server (NTRS)

Mausam, Mausau; Benazera, Emmanuel; Brafman, Roneu; Hansen, Eric

2005-01-01

We consider the problem of optimal planning in stochastic domains with metric resource constraints. Our goal is to generate a policy whose expected sum of rewards is maximized for a given initial state. We consider a general formulation motivated by our application domain--planetary exploration--in which the choice of an action at each step may depend on the current resource levels. We adapt the forward search algorithm AO* to handle our continuous state space efficiently.

Isovector and flavor-diagonal charges of the nucleon

NASA Astrophysics Data System (ADS)

Gupta, Rajan; Bhattacharya, Tanmoy; Jang, Yong-Chull; Lin, Huey-Wen; Yoon, Boram

2018-03-01

We present an update on the status of the calculations of isovector and flavor-diagonal charges of the nucleon. The calculations of the isovector charges are being done using ten 2+1+1-flavor HISQ ensembles generated by the MILC collaboration covering the range of lattice spacings a ≈ 0.12, 0.09, 0.06 fm and pion masses Mπ ≈ 310, 220, 130 MeV. Excited-states contamination is controlled by using four-state fits to two-point correlators and three-states fits to the three-point correlators. The calculations of the disconnected diagrams needed to estimate flavor-diagonal charges are being done on a subset of six ensembles using the stocastic method. Final results are obtained using a simultaneous fit in M2π, the lattice spacing a and the finite volume parameter MπL keeping only the leading order corrections.

The role of nuclear reactors in space exploration and development

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

Lipinski, R.J.

2000-07-01

The United States has launched more than 20 radioisotopic thermoelectric generators (RTGs) into space over the past 30 yr but has launched only one nuclear reactor, and that was in 1965. Russia has launched more than 30 reactors. The RTGs use the heat of alpha decay of {sup 238}Pu for power and typically generate <1 kW of electricity. Apollo, Pioneer, Voyager, Viking, Galileo, Ulysses, and Cassini all used RTGs. Space reactors use the fission energy of {sup 235}U; typical designs are for 100 to 1000 kW of electricity. The only US space reactor launch (SNAP-10A) was a demonstration mission. Onemore » reason for the lack of space reactor use by the United States was the lack of space missions that required high power. But, another was the assumed negative publicity that would accompany a reactor launch. The net result is that all space reactor programs after 1970 were terminated before an operating space reactor could be developed, and they are now many years from recovering the ability to build them. Two major near-term needs for space reactors are the human exploration of Mars and advanced missions to and beyond the orbit of Jupiter. To help obtain public acceptance of space reactors, one must correct some of the misconceptions concerning space reactors and convey the following facts to the public and to decision makers: Space reactors are 1000 times smaller in power and size than a commercial power reactor. A space reactor at launch is only as radioactive as a pile of dirt 60 m (200 ft) across. A space reactor contains no plutonium at launch. It does not become significantly radioactive until it is turned on, and it will be engineered so that no launch accident can turn it on, even if that means fueling it after launch. The reactor will not be turned on until it is in a high stable orbit or even on an earth-escape trajectory for some missions. The benefits of space reactors are that they give humanity a stairway to the planets and perhaps the stars. They open a new frontier for their children and their grandchildren. They pave the way for all life on earth to move out into the solar system. At one time, humans built and flew space reactors; it is time to do so again.« less

Device-independent characterizations of a shared quantum state independent of any Bell inequalities

NASA Astrophysics Data System (ADS)

Wei, Zhaohui; Sikora, Jamie

2017-03-01

In a Bell experiment two parties share a quantum state and perform local measurements on their subsystems separately, and the statistics of the measurement outcomes are recorded as a Bell correlation. For any Bell correlation, it turns out that a quantum state with minimal size that is able to produce this correlation can always be pure. In this work, we first exhibit two device-independent characterizations for the pure state that Alice and Bob share using only the correlation data. Specifically, we give two conditions that the Schmidt coefficients must satisfy, which can be tight, and have various applications in quantum tasks. First, one of the characterizations allows us to bound the entanglement between Alice and Bob using Renyi entropies and also to bound the underlying Hilbert space dimension. Second, when the Hilbert space dimension bound is tight, the shared pure quantum state has to be maximally entangled. Third, the second characterization gives a sufficient condition that a Bell correlation cannot be generated by particular quantum states. We also show that our results can be generalized to the case of shared mixed states.

The harmonic state of quantum cascade lasers: origin, control, and prospective applications [Invited].

PubMed

Piccardo, Marco; Chevalier, Paul; Mansuripur, Tobias S; Kazakov, Dmitry; Wang, Yongrui; Rubin, Noah A; Meadowcroft, Lauren; Belyanin, Alexey; Capasso, Federico

2018-04-16

The recently discovered ability of the quantum cascade laser to produce a harmonic frequency comb has attracted new interest in these devices for both applications and fundamental laser physics. In this review we present an extensive experimental phenomenology of the harmonic state, including its appearance in mid-infrared and terahertz quantum cascade lasers, studies of its destabilization induced by delayed optical feedback, and the assessment of its frequency comb nature. A theoretical model explaining its origin as due to the mutual interaction of population gratings and population pulsations inside the laser cavity will be described. We explore different approaches to control the spacing of the harmonic state, such as optical injection seeding and variation of the device temperature. Prospective applications of the harmonic state include microwave and terahertz generation, picosecond pulse generation in the mid-infrared, and broadband spectroscopy.

Mir Cooperative Solar Array

NASA Technical Reports Server (NTRS)

Skor, Mike; Hoffman, Dave J.

1997-01-01

The Mir Cooperative Solar Array (MCSA), produced jointly by the United States and Russia, was deployed on the Mir Russian space station on May 25, 1996. The MCSA is a photovoltaic electrical power system that can generate up to 6 kW. The power from the MCSA is needed to extend Mir's lifetime and to support experiments conducted there by visiting U.S. astronauts. The MCSA was brought to Mir via the Space Shuttle Atlantis on the STS-74 mission, launched November 12, 1995. This cooperative venture combined the best technology of both countries: the United States provided high-efficiency, lightweight photovoltaic panel modules, whereas Russia provided the array structure and deployment mechanism. Technology developed in the Space Station Freedom Program, and now being used in the International Space Station, was used to develop MCSA's photovoltaic panel. Performance data obtained from MCSA operation on Mir will help engineers better understand the performance of the photovoltaic panel modules in orbit. This information will be used to more accurately predict the performance of the International Space Station solar arrays. Managed by the NASA Lewis Research Center for NASA's International Space Station Program Office in Houston, Texas, the MCSA Project was completed on time and under budget despite a very aggressive schedule.

Prediction and generation of binary Markov processes: Can a finite-state fox catch a Markov mouse?

NASA Astrophysics Data System (ADS)

Ruebeck, Joshua B.; James, Ryan G.; Mahoney, John R.; Crutchfield, James P.

2018-01-01

Understanding the generative mechanism of a natural system is a vital component of the scientific method. Here, we investigate one of the fundamental steps toward this goal by presenting the minimal generator of an arbitrary binary Markov process. This is a class of processes whose predictive model is well known. Surprisingly, the generative model requires three distinct topologies for different regions of parameter space. We show that a previously proposed generator for a particular set of binary Markov processes is, in fact, not minimal. Our results shed the first quantitative light on the relative (minimal) costs of prediction and generation. We find, for instance, that the difference between prediction and generation is maximized when the process is approximately independently, identically distributed.

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

NASA Technical Reports Server (NTRS)

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.

Lamb Shift in the Near Field of Hyperbolic Metamaterial Half Space

NASA Astrophysics Data System (ADS)

Deng, Nai Jing; Yu, Kin Wah

2013-03-01

Hyperbolic metamaterials give a large magnification of the density of states in a specific frequency ranges, and has motivated various applications in emission lifetime reduction, strong absorption, and extraordinary black body radiation, etc. The boost of vacuum energy, which is proportional to the density of states, is expected in hyperbolic metamaterial. We have studied the Lamb shift in vacuum-hyperbolic-metamterial half spaces and shown the non-trivial role of vacuum energy. In our calculation, the easy-fabricated multilayer structure is employed to generate a hyperbolic dispersion relation. The spectrum of hydrogen atoms is calculated with a perturbation method after quantizing the half spaces with a complete mode expansion. It appears that the shift of spectrum is mainly contributed by the terahertz response of materials, which has been well described and predicted in both theories and experiments. Work supported by the General Research Fund of the Hong Kong SAR Government

Many-body instabilities and mass generation in slow Dirac materials

NASA Astrophysics Data System (ADS)

Triola, Christopher; Zhu, Jianxin; Migliori, Albert; Balatsky, Alexander

2015-03-01

Some Kondo insulators are expected to possess topologically protected surface states with linear Dirac spectrum, the topological Kondo insulators. Because the bulk states of these systems typically have heavy effective electron masses, the surface states may exhibit extraordinarily small Fermi velocities that could force the effective fine structure constant of the surface states into the strong coupling regime. Using a tight-binding model we study the many-body instabilities of these systems and identify regions of parameter space for which antiferromagnetic, ferromagnetic and charge density wave instabilities occur. Work Supported by USDOE BES E304.

Maturing Technologies for Stirling Space Power Generation

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Nowlin, Brentley C.; Dobbs, Michael W.; Schmitz, Paul C.; Huth, James

2016-01-01

Stirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint of the current state of the art. The RPS Program Office, working in collaboration with the U.S. Department of Energy (DOE), manages projects to develop thermoelectric and dynamic power systems, including Stirling Radioisotope Generators (SRGs). The Stirling Cycle Technology Development (SCTD) Project, located at Glenn Research Center (GRC), is developing Stirling-based subsystems, including convertors and controllers. The SCTD Project also performs research that focuses on a wide variety of objectives, including increasing convertor temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Research activity includes maturing subsystems, assemblies, and components to prepare them for infusion into future convertor and generator designs. The status of several technology development efforts are described here. As part of the maturation process, technologies are assessed for readiness in higher-level subsystems. To assess the readiness level of the Dual Convertor Controller (DCC), a Technology Readiness Assessment (TRA) was performed and the process and results are shown. Stirling technology research is being performed by the SCTD Project for NASA's RPS Program Office, where tasks focus on maturation of Stirling-based systems and subsystems for future space science missions.

Development of a new integrated local trajectory planning and tracking control framework for autonomous ground vehicles

NASA Astrophysics Data System (ADS)

Li, Xiaohui; Sun, Zhenping; Cao, Dongpu; Liu, Daxue; He, Hangen

2017-03-01

This study proposes a novel integrated local trajectory planning and tracking control (ILTPTC) framework for autonomous vehicles driving along a reference path with obstacles avoidance. For this ILTPTC framework, an efficient state-space sampling-based trajectory planning scheme is employed to smoothly follow the reference path. A model-based predictive path generation algorithm is applied to produce a set of smooth and kinematically-feasible paths connecting the initial state with the sampling terminal states. A velocity control law is then designed to assign a speed value at each of the points along the generated paths. An objective function considering both safety and comfort performance is carefully formulated for assessing the generated trajectories and selecting the optimal one. For accurately tracking the optimal trajectory while overcoming external disturbances and model uncertainties, a combined feedforward and feedback controller is developed. Both simulation analyses and vehicle testing are performed to verify the effectiveness of the proposed ILTPTC framework, and future research is also briefly discussed.

Cycle Trades for Nuclear Thermal Rocket Propulsion Systems

NASA Technical Reports Server (NTRS)

White, C.; Guidos, M.; Greene, W.

2003-01-01

Nuclear fission has been used as a reliable source for utility power in the United States for decades. Even in the 1940's, long before the United States had a viable space program, the theoretical benefits of nuclear power as applied to space travel were being explored. These benefits include long-life operation and high performance, particularly in the form of vehicle power density, enabling longer-lasting space missions. The configurations for nuclear rocket systems and chemical rocket systems are similar except that a nuclear rocket utilizes a fission reactor as its heat source. This thermal energy can be utilized directly to heat propellants that are then accelerated through a nozzle to generate thrust or it can be used as part of an electricity generation system. The former approach is Nuclear Thermal Propulsion (NTP) and the latter is Nuclear Electric Propulsion (NEP), which is then used to power thruster technologies such as ion thrusters. This paper will explore a number of indirect-NTP engine cycle configurations using assumed performance constraints and requirements, discuss the advantages and disadvantages of each cycle configuration, and present preliminary performance and size results. This paper is intended to lay the groundwork for future efforts in the development of a practical NTP system or a combined NTP/NEP hybrid system.

Case Studies of Extreme Space Weather Effects on the New York State (NYS) Electric Power System

NASA Astrophysics Data System (ADS)

Chantale Damas, M.; Mohamed, Ahmed; Ngwira, Chigomyezo

2017-04-01

New York State (NYS) is home to one of the largest urban cities in the world, New York City (NYC). Understanding and mitigating the effects of extreme space weather events are important to reduce the vulnerabilities of the NYS present bulk power system, which includes NYC. Extreme space weather events perturb Earth's magnetic field and generate geo-electric fields that result in the flow of Geomagnetically Induced Currents (GICs) through transmission lines, followed by transformers and ground. GICs find paths to ground through transformer grounding wires causing half-cycle saturation to their magnetic cores. This causes transformers to overheat, inject harmonics to the grid and draw more reactive power than normal. Overheating, if sustained for a long duration, may lead to transformer failure or lifetime reduction. Presented work uses results from simulations performed by the Global SWMF-generated ground geomagnetic field perturbations. Results from computed values of simulated induced geo-electric fields at specific ground-based active INTERMAGNET magnetometer sites, combined with NYS electricity transmission network real data are used to examine the vulnerabilities of the NYS power grid. As an urban city with a large population, NYC is especially vulnerable and the results from this research can be used to model power systems for other urban cities.

Development of NASA's Next Generation L-Band Digital Beamforming Synthetic Aperture Radar (DBSAR-2)

NASA Technical Reports Server (NTRS)

Rincon, Rafael; Fatoyinbo, Temilola; Osmanoglu, Batuhan; Lee, Seung-Kuk; Ranson, K. Jon; Marrero, Victor; Yeary, Mark

2014-01-01

NASA's Next generation Digital Beamforming SAR (DBSAR-2) is a state-of-the-art airborne L-band radar developed at the NASA Goddard Space Flight Center (GSFC). The instrument builds upon the advanced architectures in NASA's DBSAR-1 and EcoSAR instruments. The new instrument employs a 16-channel radar architecture characterized by multi-mode operation, software defined waveform generation, digital beamforming, and configurable radar parameters. The instrument has been design to support several disciplines in Earth and Planetary sciences. The instrument was recently completed, and tested and calibrated in a anechoic chamber.

The NASA Advanced Exploration Systems Nuclear Thermal Propulsion Project

NASA Technical Reports Server (NTRS)

Houts, Michael G.; Mitchell, Doyce P.; Kim, Tony; Emrich, William J.; Hickman, Robert R.; Gerrish, Harold P.; Doughty, Glen; Belvin, Anthony; Clement, Steven; Borowski, Stanley K.;

Locations Where Space Weather Energy Impacts the Atmosphere

NASA Astrophysics Data System (ADS)

Sojka, Jan J.

2017-11-01

In this review we consider aspects of space weather that can have a severe impact on the terrestrial atmosphere. We begin by identifying the pre-conditioning role of the Sun on the temperature and density of the upper atmosphere. This effect we define as "space climatology". Space weather effects are then defined as severe departures from this state of the atmospheric energy and density. Three specific forms of space weather are reviewed and we show that each generates severe space weather impacts. The three forms of space weather being considered are the solar photon flux (flares), particle precipitation (aurora), and electromagnetic Joule heating (magnetosphere-ionospheric (M-I) coupling). We provide an overview of the physical processes associated with each of these space weather forms. In each case a very specific altitude range exists over which the processes can most effectively impact the atmosphere. Our argument is that a severe change in the local atmosphere's state leads to atmospheric heating and other dynamic changes at locations beyond the input heat source region. All three space weather forms have their greatest atmospheric impact between 100 and 130 km. This altitude region comprises the transition between the atmosphere's mesosphere and thermosphere and is the ionosphere's E-region. This region is commonly referred to as the Space Atmosphere Interaction Region (SAIR). The SAIR also acts to insulate the lower atmosphere from the space weather impact of energy deposition. A similar space weather zone would be present in atmospheres of other planets and exoplanets.

Geometric Defects in Quantum Hall States

NASA Astrophysics Data System (ADS)

Gromov, Andrey

I will describe a geometric analogue of Laughlin quasiholes in fractional quantum Hall (FQH) states. These ``quasiholes'' are generated by an insertion of quantized fluxes of curvature - which can be modeled by branch points of a certain Riemann surface - and, consequently, are related to genons. Unlike quasiholes, the genons are not excitations, but extrinsic defects. Fusion of genons describes the response of an FQH state to a process that changes (effective) topology of the physical space. These defects are abelian for IQH states and non-abelian for FQH states. I will explain how to calculate an electric charge, geometric spin and adiabatic mutual statistics of the these defects. Leo Kadanoff Fellowship.

CO2 Removal and Atmosphere Revitalization Systems for Next Generation Space Flight

NASA Technical Reports Server (NTRS)

Luna, Bernadette; Mulloth, Lila M.; Varghese, Mini M.; Hogan, John Andrew

2010-01-01

Removal of metabolic CO2 from breathing air is a vital process for life support in all crewed space missions. A CO2 removal processor called the Low Power CO2 Removal (LPCOR) system is being developed in the Bioengineering Branch at NASA Ames Research Center. LPCOR utilizes advanced adsorption and membrane gas separation processes to achieve substantial power and mass reduction when compared to the state-of-the-art carbon dioxide removal assembly (CORA) of the US segment of the International Space Station (ISS). LPCOR is an attractive alternative for use in commercial spacecraft for short-duration missions and can easily be adapted for closed-loop life support applications. NASA envisions a next-generation closed-loop atmosphere revitalization system that integrates advanced CO2 removal, O2 recovery, and trace contaminant control processes to improve overall system efficiency. LPCOR will serve as the front end to such a system. LPCOR is a reliable air revitalization technology that can serve both the near-term and long-term human space flight needs of NASA and its commercial partners.

Innovative Ideas for Coordinating International Space Activities: International Center for Space Medicine, International Space Authority, and other Global Youth Space Initiatives

NASA Astrophysics Data System (ADS)

Marshall, W.

2002-01-01

The Space Generation Forum SGF, at UNISPACE-III, as one of its ten formal recommendations to the United Nations in 1999, put forward the suggestion that the an international space authority should be created. Other recommendations were the establishment of an International Center for Space Medicine, creation of a global space exploration and development program, establishment of a global space (Nobel) prize, and a global space library. These projects are being further developed at the Space Generation Summit (SGS), an event at World Space Congress (WSC) which shall unite international students and young professionals to develop a youth vision and strategy for the peaceful uses of space. SGS, endorsed by the United Nations, will take place from October 11- 13th, during which the 200 delegates will discuss ongoing youth space activities, particularly those stemming from the UNISPACE-III/SGF and taken forward by the Space Generation Advisory Council. Delegates will address a variety of topics with the goal of devising new recommendations according to the theme, 'Accelerating Our Pace in Space'. The material presented here and in other technical sessions throughout WSC includes the findings of these discussions. In this paper, we present the International Space Authority idea together with recommendations on how that might be taken forward. The purpose of such an organization would be to allow: 1. Oversight and enforcement for the balanced regulation of multiple interests in space 2. Access for all peoples to the material benefits and knowledge and understanding enabled by the exploration and 3. Pooling of national and industry resources for the creation of space infrastructure, missions and enterprises for Operating principles: 1. The ISA regulatory regime would encourage commercialization and the harnessing of competitive market 2. Consistent with its charter to ensure access to all peoples, all UN member states and appropriate NGOs would 3. Close coordination with appropriate industry-based bodies, e.g. the SGF-recommended International Space The Association for the Development of Aerospace Medicine was established in 1999 as a first step towards creating an International Center for Space Medicine. In this paper, we present this and other work of the SGS delegates relating to new international coordination concepts, such as the Global Education Curriculum and the global space prize.

Cryogenic optics for space application

NASA Astrophysics Data System (ADS)

Fappani, Denis; Robert, Patrick

2017-11-01

For space born Astronomy as well as Earth Observation from space, more and more focal plane instruments are operating in the near or mid infrared and require therefore optics operating at cryogenic temperature (down to liquid nitrogen temperature or less). Through several examples of typical past or on-going realizations for different projects requiring such cryogenics optics (e.g. MTG=Meteosat Third Generation program for ESA), the presentation will point out the main technical issues and corresponding solutions for design, manufacturing and testing of necessary lens assemblies, mirrors and relevant optical coatings. A brief review of the corresponding existing "state of the art" for these technologies in Thales Seso will conclude the presentation.

Photo-induced changes of the surface band bending in GaN: Influence of growth technique, doping and polarity

NASA Astrophysics Data System (ADS)

Winnerl, Andrea; Pereira, Rui N.; Stutzmann, Martin

2017-05-01

In this work, we use conductance and contact potential difference photo-transient data to study the influence of the growth technique, doping, and crystal polarity on the kinetics of photo-generated charges in GaN. We found that the processes, and corresponding time scales, involved in the decay of charge carriers generated at and close to the GaN surface via photo-excitation are notably independent of the growth technique, doping (n- and p-types), and also crystal polarity. Hence, the transfer of photo-generated charges from band states back to surface states proceeds always by hopping via shallow defect states in the space-charge region (SCR) close to the surface. Concerning the charge carrier photo-generation kinetics, we observe considerable differences between samples grown with different techniques. While for GaN grown by metal-organic chemical vapor deposition, the accumulation of photo-conduction electrons results mainly from a combined trapping-hopping process (slow), where photo-generated electrons hop via shallow defect states to the conduction band (CB), in hydride vapor phase epitaxy and molecular beam epitaxy materials, a faster direct process involving electron transfer via CB states is also present. The time scales of both processes are quite insensitive to the doping level and crystal polarity. However, these processes become irrelevant for very high doping levels (both n- and p-types), where the width of the SCR is much smaller than the photon penetration depth, and therefore, most charge carriers are generated outside the SCR.

International Space Station United States Oxygen Generator Development Testing

NASA Technical Reports Server (NTRS)

Erickson, Robert J.; Mason, Richard K.

2000-01-01

A life test of a liquid anode feed oxygen generator assembly (OGA) using SPE(R) (United Technologies Corporation, Hamilton Sundstrand Division) membrane technology was terminated in June of 1999. In the total 15,658 hours of operation at MSFC since delivery in 1995, the OGA has produced 2,103 kilograms (kg) (4,632 pounds mass (lbm)) of oxygen, and 263 kg (579 lbm) of hydrogen. Evaluation of cell stack characteristics and oxygen and hydrogen hydrophilic/hydrophobic membrane separators will be discussed.

Mechanical and electrochemical response of a LiCoO 2 cathode using reconstructed microstructures

DOE PAGES

Mendoza, Hector; Roberts, Scott Alan; Brunini, Victor; ...

2016-01-01

As LiCoO 2 cathodes are charged, delithiation of the LiCoO 2 active material leads to an increase in the lattice spacing, causing swelling of the particles. When these particles are packed into a bicontinuous, percolated network, as is the case in a battery electrode, this swelling leads to the generation of significant mechanical stress. In this study we performed coupled electrochemical-mechanical simulations of the charging of a LiCoO 2 cathode in order to elucidate the mechanisms of stress generation and the effect of charge rate and microstructure on these stresses. Energy dispersive spectroscopy combined with scanning electron microscopy imaging wasmore » used to create 3D reconstructions of a LiCoO 2 cathode, and the Conformal Decomposition Finite Element Method is used to automatically generate computational meshes on this reconstructed microstructure. Replacement of the ideal solution Fickian diffusion model, typically used in battery simulations, with a more general non-ideal solution model shows substantially smaller gradients of lithium within particles than is typically observed in the literature. Using this more general model, lithium gradients only appear at states of charge where the open-circuit voltage is relatively constant. While lithium gradients do affect the mechanical stress state in the particles, the maximum stresses are always found in the fully-charged state and are strongly affected by the local details of the microstructure and particle-to-particle contacts. These coupled electrochemical-mechanical simulations begin to yield insight into the partitioning of volume change between reducing pore space and macroscopically swelling the electrode. Lastly, preliminary studies that include the presence of the polymeric binder suggest that it can greatly impact stress generation and that it is an important area for future research.« less

Techniques for modeling the reliability of fault-tolerant systems with the Markov state-space approach

NASA Technical Reports Server (NTRS)

Butler, Ricky W.; Johnson, Sally C.

1995-01-01

This paper presents a step-by-step tutorial of the methods and the tools that were used for the reliability analysis of fault-tolerant systems. The approach used in this paper is the Markov (or semi-Markov) state-space method. The paper is intended for design engineers with a basic understanding of computer architecture and fault tolerance, but little knowledge of reliability modeling. The representation of architectural features in mathematical models is emphasized. This paper does not present details of the mathematical solution of complex reliability models. Instead, it describes the use of several recently developed computer programs SURE, ASSIST, STEM, and PAWS that automate the generation and the solution of these models.

LETTER TO THE EDITOR: Landau levels on the hyperbolic plane

NASA Astrophysics Data System (ADS)

Fakhri, H.; Shariati, M.

2004-11-01

The quantum states of a spinless charged particle on a hyperbolic plane in the presence of a uniform magnetic field with a generalized quantization condition are proved to be the bases of the irreducible Hilbert representation spaces of the Lie algebra u(1, 1). The dynamical symmetry group U(1, 1) with the explicit form of the Lie algebra generators is extracted. It is also shown that the energy has an infinite-fold degeneracy in each of the representation spaces which are allocated to the different values of the magnetic field strength. Based on the simultaneous shift of two parameters, it is also noted that the quantum states realize the representations of Lie algebra u(2) by shifting the magnetic field strength.

Building long-term constituencies for space exploration: The challenge of raising public awareness and engagement in the United States and in Europe

NASA Astrophysics Data System (ADS)

Ehrenfreund, P.; Peter, N.; Billings, L.

2010-08-01

Space exploration is a multifaceted endeavor and will be a "grand challenge" of the 21st century. It has already become an element of the political agenda of a growing number of countries worldwide. However, the public is largely unaware of space exploration activities and in particular does not perceive any personal benefit. In order to achieve highly ambitious space exploration goals to explore robotically and with humans the inner solar system, space agencies must improve and expand their efforts to inform and raise the awareness of the public about what they are doing, and why. Therefore adopting new techniques aiming at informing and engaging the public using participatory ways, new communication techniques to reach, in particular, the younger generation will be a prerequisite for a sustainable long-term exploration program: as they will enable it and carry most of the associated financial burden. This paper presents an environmental analysis of space exploration in the United States and Europe and investigates the current branding stature of the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). We discuss how improved market research and new branding methods can increase public space awareness and improve the image of NASA and ESA. We propose a new participatory approach to engage the public as major stakeholder (along governments, the industrial space sector and the science community) that may provide sufficient resources for and sustainability of a long-term space exploration program.

Symbolic Analysis of Concurrent Programs with Polymorphism

NASA Technical Reports Server (NTRS)

Rungta, Neha Shyam

2010-01-01

The current trend of multi-core and multi-processor computing is causing a paradigm shift from inherently sequential to highly concurrent and parallel applications. Certain thread interleavings, data input values, or combinations of both often cause errors in the system. Systematic verification techniques such as explicit state model checking and symbolic execution are extensively used to detect errors in such systems [7, 9]. Explicit state model checking enumerates possible thread schedules and input data values of a program in order to check for errors [3, 9]. To partially mitigate the state space explosion from data input values, symbolic execution techniques substitute data input values with symbolic values [5, 7, 6]. Explicit state model checking and symbolic execution techniques used in conjunction with exhaustive search techniques such as depth-first search are unable to detect errors in medium to large-sized concurrent programs because the number of behaviors caused by data and thread non-determinism is extremely large. We present an overview of abstraction-guided symbolic execution for concurrent programs that detects errors manifested by a combination of thread schedules and data values [8]. The technique generates a set of key program locations relevant in testing the reachability of the target locations. The symbolic execution is then guided along these locations in an attempt to generate a feasible execution path to the error state. This allows the execution to focus in parts of the behavior space more likely to contain an error.

SIMULATION FROM ENDPOINT-CONDITIONED, CONTINUOUS-TIME MARKOV CHAINS ON A FINITE STATE SPACE, WITH APPLICATIONS TO MOLECULAR EVOLUTION.

PubMed

Hobolth, Asger; Stone, Eric A

2009-09-01

Analyses of serially-sampled data often begin with the assumption that the observations represent discrete samples from a latent continuous-time stochastic process. The continuous-time Markov chain (CTMC) is one such generative model whose popularity extends to a variety of disciplines ranging from computational finance to human genetics and genomics. A common theme among these diverse applications is the need to simulate sample paths of a CTMC conditional on realized data that is discretely observed. Here we present a general solution to this sampling problem when the CTMC is defined on a discrete and finite state space. Specifically, we consider the generation of sample paths, including intermediate states and times of transition, from a CTMC whose beginning and ending states are known across a time interval of length T. We first unify the literature through a discussion of the three predominant approaches: (1) modified rejection sampling, (2) direct sampling, and (3) uniformization. We then give analytical results for the complexity and efficiency of each method in terms of the instantaneous transition rate matrix Q of the CTMC, its beginning and ending states, and the length of sampling time T. In doing so, we show that no method dominates the others across all model specifications, and we give explicit proof of which method prevails for any given Q, T, and endpoints. Finally, we introduce and compare three applications of CTMCs to demonstrate the pitfalls of choosing an inefficient sampler.

The reusable launch vehicle technology program

NASA Astrophysics Data System (ADS)

Cook, S.

Today's launch systems have major shortcomings that will increase in significance in the future, and thus are principal drivers for seeking major improvements in space transportation. They are too costly; insufficiently reliable, safe, and operable; and increasingly losing market share to international competition. For the United States to continue its leadership in the human exploration and wide ranging utilization of space, the first order of business must be to achieve low cost, reliable transportatin to Earth orbit. NASA's Access to Space Study, in 1993, recommended the development of a fully reusable single-stage-to-orbit (SSTO) rocket vehicle as an Agency goal. The goal of the Reusable Launch Vehicle (RLV) technology program is to mature the technologies essential for a next-generation reusable launch system capable of reliably serving National space transportation needs at substantially reduced costs. The primary objectives of the RLV technology program are to (1) mature the technologies required for the next-generation system, (2) demonstrate the capability to achieve low development and operational cost, and rapid launch turnaround times and (3) reduce business and technical risks to encourage significant private investment in the commercial development and operation of the next-generation system. Developing and demonstrating the technologies required for a Single Stage to Orbit (SSTO) rocket is a focus of the program becuase past studies indicate that it has the best potential for achieving the lowest space access cost while acting as an RLV technology driver (since it also encompasses the technology requirements of reusable rocket vehicles in general).

The reusable launch vehicle technology program

NASA Technical Reports Server (NTRS)

Cook, S.

1995-01-01

Today's launch systems have major shortcomings that will increase in significance in the future, and thus are principal drivers for seeking major improvements in space transportation. They are too costly; insufficiently reliable, safe, and operable; and increasingly losing market share to international competition. For the United States to continue its leadership in the human exploration and wide ranging utilization of space, the first order of business must be to achieve low cost, reliable transportatin to Earth orbit. NASA's Access to Space Study, in 1993, recommended the development of a fully reusable single-stage-to-orbit (SSTO) rocket vehicle as an Agency goal. The goal of the Reusable Launch Vehicle (RLV) technology program is to mature the technologies essential for a next-generation reusable launch system capable of reliably serving National space transportation needs at substantially reduced costs. The primary objectives of the RLV technology program are to (1) mature the technologies required for the next-generation system, (2) demonstrate the capability to achieve low development and operational cost, and rapid launch turnaround times and (3) reduce business and technical risks to encourage significant private investment in the commercial development and operation of the next-generation system. Developing and demonstrating the technologies required for a Single Stage to Orbit (SSTO) rocket is a focus of the program becuase past studies indicate that it has the best potential for achieving the lowest space access cost while acting as an RLV technology driver (since it also encompasses the technology requirements of reusable rocket vehicles in general).

Defense Acquisition Workforce: The Air Force Needs to Evaluate Changes in Funding for Civilians Engaged in Space Acquisition

DTIC Science & Technology

2013-07-01

1) revitalize the acquisition workforce; (2) improve the requirements generation process; (3) instill budget and financial DOD Acquisition...with our four recommended actions (see app . I). In concurring with our recommendations, DOD stated that the Air Force will evaluate the pilot program

78 FR 24323 - National Park Week, 2013

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-24

... National Park Week, 2013 By the President of the United States of America A Proclamation For generations... something to be used up, but as a treasure to be passed on. During National Park Week, we celebrate the... spaces embody the best of the American spirit, and they summon us to experience it firsthand. This week...

Mixed analytical-stochastic simulation method for the recovery of a Brownian gradient source from probability fluxes to small windows.

PubMed

Dobramysl, U; Holcman, D

2018-02-15

Is it possible to recover the position of a source from the steady-state fluxes of Brownian particles to small absorbing windows located on the boundary of a domain? To address this question, we develop a numerical procedure to avoid tracking Brownian trajectories in the entire infinite space. Instead, we generate particles near the absorbing windows, computed from the analytical expression of the exit probability. When the Brownian particles are generated by a steady-state gradient at a single point, we compute asymptotically the fluxes to small absorbing holes distributed on the boundary of half-space and on a disk in two dimensions, which agree with stochastic simulations. We also derive an expression for the splitting probability between small windows using the matched asymptotic method. Finally, when there are more than two small absorbing windows, we show how to reconstruct the position of the source from the diffusion fluxes. The present approach provides a computational first principle for the mechanism of sensing a gradient of diffusing particles, a ubiquitous problem in cell biology.

Quantum Theory of Conditional Phonon States in a Dual-Pumped Raman Optical Frequency Comb

NASA Astrophysics Data System (ADS)

Mondloch, Erin

In this work, we theoretically and numerically investigate nonclassical phonon states created in the collective vibration of a Raman medium by the generation of a dual-pumped Raman optical frequency comb in an optical cavity. This frequency comb is generated by cascaded Raman scattering driven by two phase-locked pump lasers that are separated in frequency by three times the Raman phonon frequency. We characterize the variety of conditioned phonon states that are created when the number of photons in all optical frequency modes except the pump modes are measured. Almost all of these conditioned phonon states are extremely well approximated as three-phonon-squeezed states or Schrodinger-cat states, depending on the outcomes of the photon number measurements. We show how the combinations of first-, second-, and third-order Raman scattering that correspond to each set of measured photon numbers determine the fidelity of the conditioned phonon state with model three-phonon-squeezed states and Schrodinger-cat states. All of the conditioned phonon states demonstrate preferential growth of the phonon mode along three directions in phase space. That is, there are three preferred phase values that the phonon state takes on as a result of Raman scattering. We show that the combination of Raman processes that produces a given set of measured photon numbers always produces phonons in multiples of three. In the quantum number-state representation, these multiples of three are responsible for the threefold phase-space symmetry seen in the conditioned phonon states. With a semiclassical model, we show how this three-phase preference can also be understood in light of phase correlations that are known to spontaneously arise in single-pumped Raman frequency combs. Additionally, our semiclassical model predicts that the optical modes also grow preferentially along three phases, suggesting that the dual-pumped Raman optical frequency comb is partially phase-stabilized.

The quantum holonomy-diffeomorphism algebra and quantum gravity

NASA Astrophysics Data System (ADS)

Aastrup, Johannes; Grimstrup, Jesper Møller

2016-03-01

We introduce the quantum holonomy-diffeomorphism ∗-algebra, which is generated by holonomy-diffeomorphisms on a three-dimensional manifold and translations on a space of SU(2)-connections. We show that this algebra encodes the canonical commutation relations of canonical quantum gravity formulated in terms of Ashtekar variables. Furthermore, we show that semiclassical states exist on the holonomy-diffeomorphism part of the algebra but that these states cannot be extended to the full algebra. Via a Dirac-type operator we derive a certain class of unbounded operators that act in the GNS construction of the semiclassical states. These unbounded operators are the type of operators, which we have previously shown to entail the spatial three-dimensional Dirac operator and Dirac-Hamiltonian in a semiclassical limit. Finally, we show that the structure of the Hamilton constraint emerges from a Yang-Mills-type operator over the space of SU(2)-connections.

Preprocessing for Eddy Dissipation Rate and TKE Profile Generation

NASA Technical Reports Server (NTRS)

Zak, J. Allen; Rodgers, William G., Jr.; McKissick, Burnell T. (Technical Monitor)

2001-01-01

The Aircraft Vortex Spacing System (AVOSS), a set of algorithms to determine aircraft spacing according to wake vortex behavior prediction, requires turbulence profiles to appropriately determine arrival and departure aircraft spacing. The ambient atmospheric turbulence profile must always be produced, even if the result is an arbitrary (canned) profile. The original turbulence profile code was generated By North Carolina State University and used in a non-real-time environment in the past. All the input parameters could be carefully selected and screened prior to input. Since this code must run in real-time using actual measurements in the field as input, it became imperative to begin a data checking and screening process as part of the real-time implementation. The process described herein is a step towards ensuring that the best possible turbulence profile is always provided to AVOSS. Data fill-ins, constant profiles and arbitrary profiles are used only as a last resort, but are essential to ensure uninterrupted application of AVOSS.

System Mass Variation and Entropy Generation in 100k We Closed-Brayton-Cycle Space Power Systems

NASA Technical Reports Server (NTRS)

Barrett, Michael J.; Reid, Bryan M.

2004-01-01

State-of-the-art closed-Brayton-cycle (CBC) space power systems were modeled to study performance trends in a trade space characteristic of interplanetary orbiters. For working-fluid molar masses of 48.6, 39.9, and 11.9 kg/kmol, peak system pressures of 1.38 and 3.0 MPa and compressor pressure ratios ranging from 1.6 to 2.4, total system masses were estimated. System mass increased as peak operating pressure increased for all compressor pressure ratios and molar mass values examined. Minimum mass point comparison between 72 percent He at 1.38 MPa peak and 94 percent He at 3.0 MPa peak showed an increase in system mass of 14 percent. Converter flow loop entropy generation rates were calculated for 1.38 and 3.0 MPa peak pressure cases. Physical system behavior was approximated using a pedigreed NASA Glenn modeling code, Closed Cycle Engine Program (CCEP), which included realistic performance prediction for heat exchangers, radiators and turbomachinery.

System Mass Variation and Entropy Generation in 100-kWe Closed-Brayton-Cycle Space Power Systems

NASA Technical Reports Server (NTRS)

Barrett, Michael J.; Reid, Bryan M.

2004-01-01

State-of-the-art closed-Brayton-cycle (CBC) space power systems were modeled to study performance trends in a trade space characteristic of interplanetary orbiters. For working-fluid molar masses of 48.6, 39.9, and 11.9 kg/kmol, peak system pressures of 1.38 and 3.0 MPa and compressor pressure ratios ranging from 1.6 to 2.4, total system masses were estimated. System mass increased as peak operating pressure increased for all compressor pressure ratios and molar mass values examined. Minimum mass point comparison between 72 percent He at 1.38 MPa peak and 94 percent He at 3.0 MPa peak showed an increase in system mass of 14 percent. Converter flow loop entropy generation rates were calculated for 1.38 and 3.0 MPa peak pressure cases. Physical system behavior was approximated using a pedigreed NASA Glenn modeling code, Closed Cycle Engine Program (CCEP), which included realistic performance prediction for heat exchangers, radiators and turbomachinery.

A Multi-Wavelength IR Laser for Space Applications

NASA Technical Reports Server (NTRS)

Li, Steven X.; Yu, Anthony W.; Sun, Xiaoli; Fahey, Molly E.; Numata, Kenji; Krainak, Michael A.

2017-01-01

We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to mid-infrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 microns, 2.7 microns and 3.4 microns. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated.

A multi-wavelength IR laser for space applications

NASA Astrophysics Data System (ADS)

Li, Steven X.; Yu, Anthony W.; Sun, Xiaoli; Fahey, Molly E.; Numata, Kenji; Krainak, Michael A.

2017-05-01

We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to midinfrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 µm, 2.7 μm and 3.4 μm. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated

Practical Quantum Cryptography for Secure Free-Space Communications

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

Buttler, W.T.; Hughes, R.J.; Kwiat, P.G.

1999-02-01

Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics and information-theoretically secure post-processing methods. An adversary can neither successfully tap the quantum transmissions, nor evade detection, owing to Heisenberg's uncertainty principle. In this paper we describe the theory of quantum cryptography, and the most recent results from our experimental free-space system with which we have demonstrated for the first time the feasibility of quantum key generation overmore » a point-to-point outdoor atmospheric path in daylight. We achieved a transmission distance of 0.5 km, which was limited only by the length of the test range. Our results provide strong evidence that cryptographic key material could be generated on demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on orbit. We present a feasibility analysis of surface-to-satellite quantum key generation.« less

FREE-SPACE QUANTUM CRYPTOGRAPHY IN DAYLIGHT

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

Hughes, R.J.; Buttler, W.T.

2000-01-01

Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics and information-theoretically secure post-processing methods. An adversary can neither successfully tap the quantum transmissions, nor evade detection, owing to Heisenberg's uncertainty principle. In this paper we describe the theory of quantum cryptography, and the most recent results from our experimental free-space system with which we have demonstrated for the first time the feasibility of quantum key generation overmore » a point-to-point outdoor atmospheric path in daylight. We achieved a transmission distance of 0.5 km, which was limited only by the length of the test range. Our results provide strong evidence that cryptographic key material could be generated on demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on orbit. We present a feasibility analysis of surface-to-satellite quantum key generation.« less

CCMC: Serving research and space weather communities with unique space weather services, innovative tools and resources

NASA Astrophysics Data System (ADS)

Zheng, Yihua; Kuznetsova, Maria M.; Pulkkinen, Antti; Maddox, Marlo

2015-04-01

With the addition of Space Weather Research Center (a sub-team within CCMC) in 2010 to address NASA’s own space weather needs, CCMC has become a unique entity that not only facilitates research through providing access to the state-of-the-art space science and space weather models, but also plays a critical role in providing unique space weather services to NASA robotic missions, developing innovative tools and transitioning research to operations via user feedback. With scientists, forecasters and software developers working together within one team, through close and direct connection with space weather customers and trusted relationship with model developers, CCMC is flexible, nimble and effective to meet customer needs. In this presentation, we highlight a few unique aspects of CCMC/SWRC’s space weather services, such as addressing space weather throughout the solar system, pushing the frontier of space weather forecasting via the ensemble approach, providing direct personnel and tool support for spacecraft anomaly resolution, prompting development of multi-purpose tools and knowledge bases, and educating and engaging the next generation of space weather scientists.

VDAC electronics: 3. VDAC-Creatine kinase-dependent generation of the outer membrane potential in respiring mitochondria.

PubMed

Lemeshko, Victor V

2016-07-01

Mitochondrial energy in cardiac cells has been reported to be channeled into the cytosol through the intermembrane contact sites formed by the adenine nucleotide translocator, creatine kinase and VDAC. Computational analysis performed in this study showed a high probability of the outer membrane potential (OMP) generation coupled to such a mechanism of energy channeling in respiring mitochondria. OMPs, positive inside, calculated at elevated concentrations of creatine are high enough to restrict ATP release from mitochondria, to significantly decrease the apparent K(m,ADP) for state 3 respiration and to maintain low concentrations of Ca(2+) in the mitochondrial intermembrane space. An inhibition by creatine of Ca(2+)-induced swelling of isolated mitochondria and other protective effects of creatine reported in the literature might be explained by generated positive OMP. We suggest that VDAC-creatine kinase-dependent generation of OMP represents a novel physiological factor controlling metabolic state of mitochondria, cell energy channeling and resistance to death. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental study on trace chemical contaminant generation rates of human metabolism in spacecraft crew module

NASA Astrophysics Data System (ADS)

Lihua, Guo; Xinxing, He; Guoxin, Xu; Xin, Qi

2012-12-01

Trace chemical contaminants generated by human metabolism is a major source of contamination in spacecraft crew module. In this research, types and generation rates of pollutants from human metabolism were determined in the Chinese diets. Expired air, skin gas, and sweat of 20 subjects were analyzed at different exercise states in a simulated module. The exercise states were designed according to the basic activities in the orbit of astronauts. Qualitative and quantitative analyses of contaminants generated by human metabolic were performed with gas chromatography/mass spectrometry, gas chromatography and UV spectrophotometer. Sixteen chemical compounds from metabolic sources were found. With the increase in physical load, the concentrations of chemical compounds from human skin and expired air correspondingly increased. The species and the offgassing rates of pollutants from human metabolism are different among the Chinese, Americans and the Russians due to differences in ethnicity and dietary customs. This research provides data to aid in the design, development and operation of China's long duration space mission.

Inverse problem for multispecies ferromagneticlike mean-field models in phase space with many states

NASA Astrophysics Data System (ADS)

Fedele, Micaela; Vernia, Cecilia

2017-10-01

In this paper we solve the inverse problem for the Curie-Weiss model and its multispecies version when multiple thermodynamic states are present as in the low temperature phase where the phase space is clustered. The inverse problem consists of reconstructing the model parameters starting from configuration data generated according to the distribution of the model. We demonstrate that, without taking into account the presence of many states, the application of the inversion procedure produces very poor inference results. To overcome this problem, we use the clustering algorithm. When the system has two symmetric states of positive and negative magnetizations, the parameter reconstruction can also be obtained with smaller computational effort simply by flipping the sign of the magnetizations from positive to negative (or vice versa). The parameter reconstruction fails when the system undergoes a phase transition: In that case we give the correct inversion formulas for the Curie-Weiss model and we show that they can be used to measure how close the system gets to being critical.

Flight State Identification of a Self-Sensing Wing via an Improved Feature Selection Method and Machine Learning Approaches.

PubMed

Chen, Xi; Kopsaftopoulos, Fotis; Wu, Qi; Ren, He; Chang, Fu-Kuo

2018-04-29

In this work, a data-driven approach for identifying the flight state of a self-sensing wing structure with an embedded multi-functional sensing network is proposed. The flight state is characterized by the structural vibration signals recorded from a series of wind tunnel experiments under varying angles of attack and airspeeds. A large feature pool is created by extracting potential features from the signals covering the time domain, the frequency domain as well as the information domain. Special emphasis is given to feature selection in which a novel filter method is developed based on the combination of a modified distance evaluation algorithm and a variance inflation factor. Machine learning algorithms are then employed to establish the mapping relationship from the feature space to the practical state space. Results from two case studies demonstrate the high identification accuracy and the effectiveness of the model complexity reduction via the proposed method, thus providing new perspectives of self-awareness towards the next generation of intelligent air vehicles.

Hardware-efficient Bell state preparation using Quantum Zeno Dynamics in superconducting circuits

NASA Astrophysics Data System (ADS)

Flurin, Emmanuel; Blok, Machiel; Hacohen-Gourgy, Shay; Martin, Leigh S.; Livingston, William P.; Dove, Allison; Siddiqi, Irfan

By preforming a continuous joint measurement on a two qubit system, we restrict the qubit evolution to a chosen subspace of the total Hilbert space. This extension of the quantum Zeno effect, called Quantum Zeno Dynamics, has already been explored in various physical systems such as superconducting cavities, single rydberg atoms, atomic ensembles and Bose Einstein condensates. In this experiment, two superconducting qubits are strongly dispersively coupled to a high-Q cavity (χ >> κ) allowing for the doubly excited state | 11 〉 to be selectively monitored. The Quantum Zeno Dynamics in the complementary subspace enables us to coherently prepare a Bell state. As opposed to dissipation engineering schemes, we emphasize that our protocol is deterministic, does not rely direct coupling between qubits and functions only using single qubit controls and cavity readout. Such Quantum Zeno Dynamics can be generalized to larger Hilbert space enabling deterministic generation of many-body entangled states, and thus realizes a decoherence-free subspace allowing alternative noise-protection schemes.

KSC-2014-3927

NASA Image and Video Library

2014-09-16

CAPE CANAVERAL, Fla. – Former astronaut Bob Cabana, director of NASA's Kennedy Space Center in Florida, speaks at the start of the announcement ceremony to name the providers of the next generation of crewed American spacecraft. Speaking from Kennedy’s Press Site, Cabana detailed the importance of the development effort by the agency's Commercial Crew Program for United States space exploration ambitions and the economic potential of creating new markets in human space transportation. Boeing and SpaceX were awarded contracts to complete the design of the CST-100 and Crew Dragon spacecraft, respectively, and begin manufacturing for flight tests with a goal of achieving certification to take astronauts to the International Space Station by 2017. The Commercial Crew Transportation Capability CCtCap contract also covers the beginning of operational missions for these new spacecraft and their systems. Photo credit: NASA/Jim Grossmann

Biologically-Inspired Spike-Based Automatic Speech Recognition of Isolated Digits Over a Reproducing Kernel Hilbert Space

PubMed Central

Li, Kan; Príncipe, José C.

2018-01-01

This paper presents a novel real-time dynamic framework for quantifying time-series structure in spoken words using spikes. Audio signals are converted into multi-channel spike trains using a biologically-inspired leaky integrate-and-fire (LIF) spike generator. These spike trains are mapped into a function space of infinite dimension, i.e., a Reproducing Kernel Hilbert Space (RKHS) using point-process kernels, where a state-space model learns the dynamics of the multidimensional spike input using gradient descent learning. This kernelized recurrent system is very parsimonious and achieves the necessary memory depth via feedback of its internal states when trained discriminatively, utilizing the full context of the phoneme sequence. A main advantage of modeling nonlinear dynamics using state-space trajectories in the RKHS is that it imposes no restriction on the relationship between the exogenous input and its internal state. We are free to choose the input representation with an appropriate kernel, and changing the kernel does not impact the system nor the learning algorithm. Moreover, we show that this novel framework can outperform both traditional hidden Markov model (HMM) speech processing as well as neuromorphic implementations based on spiking neural network (SNN), yielding accurate and ultra-low power word spotters. As a proof of concept, we demonstrate its capabilities using the benchmark TI-46 digit corpus for isolated-word automatic speech recognition (ASR) or keyword spotting. Compared to HMM using Mel-frequency cepstral coefficient (MFCC) front-end without time-derivatives, our MFCC-KAARMA offered improved performance. For spike-train front-end, spike-KAARMA also outperformed state-of-the-art SNN solutions. Furthermore, compared to MFCCs, spike trains provided enhanced noise robustness in certain low signal-to-noise ratio (SNR) regime. PMID:29666568

Biologically-Inspired Spike-Based Automatic Speech Recognition of Isolated Digits Over a Reproducing Kernel Hilbert Space.

PubMed

Li, Kan; Príncipe, José C

2018-01-01

This paper presents a novel real-time dynamic framework for quantifying time-series structure in spoken words using spikes. Audio signals are converted into multi-channel spike trains using a biologically-inspired leaky integrate-and-fire (LIF) spike generator. These spike trains are mapped into a function space of infinite dimension, i.e., a Reproducing Kernel Hilbert Space (RKHS) using point-process kernels, where a state-space model learns the dynamics of the multidimensional spike input using gradient descent learning. This kernelized recurrent system is very parsimonious and achieves the necessary memory depth via feedback of its internal states when trained discriminatively, utilizing the full context of the phoneme sequence. A main advantage of modeling nonlinear dynamics using state-space trajectories in the RKHS is that it imposes no restriction on the relationship between the exogenous input and its internal state. We are free to choose the input representation with an appropriate kernel, and changing the kernel does not impact the system nor the learning algorithm. Moreover, we show that this novel framework can outperform both traditional hidden Markov model (HMM) speech processing as well as neuromorphic implementations based on spiking neural network (SNN), yielding accurate and ultra-low power word spotters. As a proof of concept, we demonstrate its capabilities using the benchmark TI-46 digit corpus for isolated-word automatic speech recognition (ASR) or keyword spotting. Compared to HMM using Mel-frequency cepstral coefficient (MFCC) front-end without time-derivatives, our MFCC-KAARMA offered improved performance. For spike-train front-end, spike-KAARMA also outperformed state-of-the-art SNN solutions. Furthermore, compared to MFCCs, spike trains provided enhanced noise robustness in certain low signal-to-noise ratio (SNR) regime.

Common benefit from a perspective of "Non-traditional Partners": A proposed agenda to address the status quo in Global Space Governance

NASA Astrophysics Data System (ADS)

Aganaba-Jeanty, Timiebi

2015-12-01

It is presupposed that there is a dominant position in interpreting the freedom of Outer Space which has not given much real significance to the idea of common benefit. The reason that this causes difficulty is that there is an ambiguity to common benefit. This dominant position however sees the issue of benefit sharing in the context of the perceived tension between established space faring nations and emerging and aspirant States and the idea that freedom could take on a different meaning depending on where one is on the scale of development. It fails to recognize that solutions to contemporary and historical governance challenges have been much less oriented towards the interests of less developed States or new entrants, making the accrual and sharing of benefits dependent on the free will of those States able to carry out a variety of space activities independently. As a result of this, the debate around common benefit is exploited to seek individual benefit derived for a State as opposed to what our effort to use space collectively can generate. In recent times, the issue has not received much attention. This is because it is believed to be partly resolved through normative frameworks such as Article 1 of the Outer Space Treaty and the Space Benefits Declaration. While an attempt to re-address historical contentious issues, asserted to be resolved, may appear illusory or futile; such analysis can be useful depending on the account that the reader believes should be given to the normative character of human nature. To this end, the writings of legal, political and social theorists and methodologies from Critical Legal Schools may prove insightful for a deeper contextualization of the historical debate, the current understanding of the freedoms of Outer Space as well as unearth future perspectives to aid in addressing the current pressing space related issue of our time: Sustainability of Space Activities. This article proposes three main issue areas to investigate to find solutions to some of the perceived tensions prevalent in space governance:

NASA Missions Enabled by Space Nuclear Systems

NASA Technical Reports Server (NTRS)

Scott, John H.; Schmidt, George R.

2009-01-01

This viewgraph presentation reviews NASA Space Missions that are enabled by Space Nuclear Systems. The topics include: 1) Space Nuclear System Applications; 2) Trade Space for Electric Power Systems; 3) Power Generation Specific Energy Trade Space; 4) Radioisotope Power Generation; 5) Radioisotope Missions; 6) Fission Power Generation; 7) Solar Powered Lunar Outpost; 8) Fission Powered Lunar Outpost; 9) Fission Electric Power Generation; and 10) Fission Nuclear Thermal Propulsion.

Discrete Dynamics Lab

NASA Astrophysics Data System (ADS)

Wuensche, Andrew

DDLab is interactive graphics software for creating, visualizing, and analyzing many aspects of Cellular Automata, Random Boolean Networks, and Discrete Dynamical Networks in general and studying their behavior, both from the time-series perspective — space-time patterns, and from the state-space perspective — attractor basins. DDLab is relevant to research, applications, and education in the fields of complexity, self-organization, emergent phenomena, chaos, collision-based computing, neural networks, content addressable memory, genetic regulatory networks, dynamical encryption, generative art and music, and the study of the abstract mathematical/physical/dynamical phenomena in their own right.

Applying CASE Tools for On-Board Software Development

NASA Astrophysics Data System (ADS)

Brammer, U.; Hönle, A.

For many space projects the software development is facing great pressure with respect to quality, costs and schedule. One way to cope with these challenges is the application of CASE tools for automatic generation of code and documentation. This paper describes two CASE tools: Rhapsody (I-Logix) featuring UML and ISG (BSSE) that provides modeling of finite state machines. Both tools have been used at Kayser-Threde in different space projects for the development of on-board software. The tools are discussed with regard to the full software development cycle.

Hybrid Power Management (HPM) Program Resulted in Several New Applications

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.

2003-01-01

Hybrid Power Management (HPM) is the innovative integration of diverse, state-of-the-art power devices in an optimal configuration for space and terrestrial applications. The appropriate application and control of the various power devices significantly improves overall system performance and efficiency. The advanced power devices include ultracapacitors, fuel cells, and photovoltaics. HPM has extremely wide potential with applications from nanowatts to megawatts. Applications include power generation, transportation systems, biotechnology systems, and space power systems. HPM has the potential to significantly alleviate global energy concerns, improve the environment, and stimulate the economy.

ACOSS Three (Active Control of Space Structures). Phase I.

DTIC Science & Technology

1980-05-01

their assorted pitfalls, programs such as NASTRAN, SPAR, ASTRO , etc., are never-the-less the primary tools for generating dynamical models of...proofs and additional details, see Ref [*] Consider the system described in state-space form by: Dynamics: X = FX + Gu Sensors: y = HX = (F +GCH)X (1...input u and output y = Fx + Gu (6) y = Hx+Du (7) The input-output transfer function is given by y = (H(sI- F)-1G +D)u (8) or y(s) _ 1 N u(s) A(s) E

Metastable state en route to traveling-wave synchronization state

NASA Astrophysics Data System (ADS)

Park, Jinha; Kahng, B.

2018-02-01

The Kuramoto model with mixed signs of couplings is known to produce a traveling-wave synchronized state. Here, we consider an abrupt synchronization transition from the incoherent state to the traveling-wave state through a long-lasting metastable state with large fluctuations. Our explanation of the metastability is that the dynamic flow remains within a limited region of phase space and circulates through a few active states bounded by saddle and stable fixed points. This complex flow generates a long-lasting critical behavior, a signature of a hybrid phase transition. We show that the long-lasting period can be controlled by varying the density of inhibitory/excitatory interactions. We discuss a potential application of this transition behavior to the recovery process of human consciousness.

Robotics technology developments in the United States space telerobotics program

NASA Technical Reports Server (NTRS)

Lavery, David

1994-01-01

In the same way that the launch of Yuri Gagarin in April 1961 announced the beginning of human space flight, last year's flight of the German ROTEX robot flight experiment is heralding the start of a new era of space robotics. After a gap of twelve years since the introduction of a new capability in space remote manipulation, ROTEX is the first of at least ten new robotic systems and experiments which will fly before the year 2000. As a result of redefining the development approach for space robotic systems, and capitalizing on opportunities associated with the assembly and maintenance of the space station, the space robotics community is preparing a whole new generation of operational robotic capabilities. Expanding on the capabilities of earlier manipulation systems such as the Viking and Surveyor soil scoops, the Russian Lunakhods, and the Shuttle Remote Manipulator System (RMS), these new space robots will augment astronaut on-orbit capabilities and extend virtual human presence to lunar and planetary surfaces.

Chiral Modes at Exceptional Points in Exciton-Polariton Quantum Fluids

NASA Astrophysics Data System (ADS)

Gao, T.; Li, G.; Estrecho, E.; Liew, T. C. H.; Comber-Todd, D.; Nalitov, A.; Steger, M.; West, K.; Pfeiffer, L.; Snoke, D. W.; Kavokin, A. V.; Truscott, A. G.; Ostrovskaya, E. A.

2018-02-01

We demonstrate the generation of chiral modes-vortex flows with fixed handedness in exciton-polariton quantum fluids. The chiral modes arise in the vicinity of exceptional points (non-Hermitian spectral degeneracies) in an optically induced resonator for exciton polaritons. In particular, a vortex is generated by driving two dipole modes of the non-Hermitian ring resonator into degeneracy. Transition through the exceptional point in the space of the system's parameters is enabled by precise manipulation of real and imaginary parts of the closed-wall potential forming the resonator. As the system is driven to the vicinity of the exceptional point, we observe the formation of a vortex state with a fixed orbital angular momentum (topological charge). This method can be extended to generate higher-order orbital angular momentum states through coalescence of multiple non-Hermitian spectral degeneracies. Our Letter demonstrates the possibility of exploiting nontrivial and counterintuitive properties of waves near exceptional points in macroscopic quantum systems.

Quasi-lattices of qubits for generating inequivalent multipartite entanglements

NASA Astrophysics Data System (ADS)

Ian, Hou

2016-06-01

The mesoscopic scale of superconducting qubits makes their inter-spacings comparable to the scale of wavelength of a circuit cavity field to which they commonly couple. This comparability results in inhomogeneous coupling strengths for each qubit and hence asynchronous Rabi excitation cycles among the qubits that form a quasi-lattice. We find that such inhomogeneous coupling benefits the formation of multi-photon resonances between the single-mode cavity field and the quasi-lattice. The multi-photon resonances lead, in turn, to the simultaneous generation of inequivalent |\\text{GHZ}> and |W> types of multipartite entanglement states, which are not transformable to each other through local operations with classical communications. Applying the model on the 3-qubit quasi-lattice and using the entanglement measures of both concurrence and 3-tangle, we verify that the inhomogeneous coupling specifically promotes the generation of the totally inseparable |\\text{GHZ}> state.

Generation of elliptical and circular vector hollow beams with different polarizations by a Mach-Zehnder-type optical path

NASA Astrophysics Data System (ADS)

Wang, Zhizhang; Pei, Chunying; Xia, Meng; Yin, Yaling; Xia, Yong; Yin, Jianping

2018-01-01

We present an experimental approach to convert linearly polarized Gaussian beams into elliptical and circular vector hollow beams (VHBs) with different polarization states. The scheme employed is based on a Mach-Zehnder-type optical path combined with a reflective spatial light modulator (SLM) in each path. The resulting VHBs have radial, azimuthal, and other polarization states. Our studies also show that the size of the generated VHBs remains constant during the propagation in free space over a certain distance, and can be controlled by the axial ratio of the SLM’s binary phase plate. These studies deliver great optical parameters and hold promising applications in the fields of optical trapping and manipulation of particles.

Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space.

PubMed

Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J

2013-01-01

Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies.

Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space

PubMed Central

Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J.

2013-01-01

Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies. PMID:24156059

Fault diagnosis based on continuous simulation models

NASA Technical Reports Server (NTRS)

Feyock, Stefan

1987-01-01

The results are described of an investigation of techniques for using continuous simulation models as basis for reasoning about physical systems, with emphasis on the diagnosis of system faults. It is assumed that a continuous simulation model of the properly operating system is available. Malfunctions are diagnosed by posing the question: how can we make the model behave like that. The adjustments that must be made to the model to produce the observed behavior usually provide definitive clues to the nature of the malfunction. A novel application of Dijkstra's weakest precondition predicate transformer is used to derive the preconditions for producing the required model behavior. To minimize the size of the search space, an envisionment generator based on interval mathematics was developed. In addition to its intended application, the ability to generate qualitative state spaces automatically from quantitative simulations proved to be a fruitful avenue of investigation in its own right. Implementations of the Dijkstra transform and the envisionment generator are reproduced in the Appendix.

Equations of motion for a spectrum-generating algebra: Lipkin Meshkov Glick model

NASA Astrophysics Data System (ADS)

Rosensteel, G.; Rowe, D. J.; Ho, S. Y.

2008-01-01

For a spectrum-generating Lie algebra, a generalized equations-of-motion scheme determines numerical values of excitation energies and algebra matrix elements. In the approach to the infinite particle number limit or, more generally, whenever the dimension of the quantum state space is very large, the equations-of-motion method may achieve results that are impractical to obtain by diagonalization of the Hamiltonian matrix. To test the method's effectiveness, we apply it to the well-known Lipkin-Meshkov-Glick (LMG) model to find its low-energy spectrum and associated generator matrix elements in the eigenenergy basis. When the dimension of the LMG representation space is 106, computation time on a notebook computer is a few minutes. For a large particle number in the LMG model, the low-energy spectrum makes a quantum phase transition from a nondegenerate harmonic vibrator to a twofold degenerate harmonic oscillator. The equations-of-motion method computes critical exponents at the transition point.

NASA's Nuclear Thermal Propulsion Project

NASA Technical Reports Server (NTRS)

Houts, Michael G.; Mitchell, Doyce P.; Kim, Tony; Emrich, William J.; Hickman, Robert R.; Gerrish, Harold P.; Doughty, Glen; Belvin, Anthony; Clement, Steven; Borowski, Stanley K.;

The environmental heat flux routine, version 4 (EHFR-4) and Multiple Reflections Routine (MRR), volume 1

NASA Technical Reports Server (NTRS)

Dietz, J. B.

1973-01-01

The environmental heat flux routine version 4, (EHFR-4) is a generalized computer program which calculates the steady state and/or transient thermal environments experienced by a space system during lunar surface, deep space, or thermal vacuum chamber operation. The specific environments possible for EHFR analysis include: lunar plain, lunar crater, combined lunar plain and crater, lunar plain in the region of spacecraft surfaces, intervehicular, deep space in the region of spacecraft surfaces, and thermal vacuum chamber generation. The EHFR was used for Extra Vehicular Mobility Unit environment analysis of the Apollo 11-17 missions, EMU manned and unmanned thermal vacuum qualification testing, and EMU-LRV interface environmental analyses.

Langley aeronautics and space test highlights, 1983

NASA Technical Reports Server (NTRS)

1984-01-01

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Some of the significant tests which were performed during calendar year 1983 in Langley test facilities, a number of which are unique in the world are highlighted. Both the broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research are illustrated.

An approach to solving large reliability models

NASA Technical Reports Server (NTRS)

Boyd, Mark A.; Veeraraghavan, Malathi; Dugan, Joanne Bechta; Trivedi, Kishor S.

1988-01-01

This paper describes a unified approach to the problem of solving large realistic reliability models. The methodology integrates behavioral decomposition, state trunction, and efficient sparse matrix-based numerical methods. The use of fault trees, together with ancillary information regarding dependencies to automatically generate the underlying Markov model state space is proposed. The effectiveness of this approach is illustrated by modeling a state-of-the-art flight control system and a multiprocessor system. Nonexponential distributions for times to failure of components are assumed in the latter example. The modeling tool used for most of this analysis is HARP (the Hybrid Automated Reliability Predictor).

Visualizing protein partnerships in living cells and organisms.

PubMed

Lowder, Melissa A; Appelbaum, Jacob S; Hobert, Elissa M; Schepartz, Alanna

2011-12-01

In recent years, scientists have expanded their focus from cataloging genes to characterizing the multiple states of their translated products. One anticipated result is a dynamic map of the protein association networks and activities that occur within the cellular environment. While in vitro-derived network maps can illustrate which of a multitude of possible protein-protein associations could exist, they supply a falsely static picture lacking the subtleties of subcellular location (where) or cellular state (when). Generating protein association network maps that are informed by both subcellular location and cell state requires novel approaches that accurately characterize the state of protein associations in living cells and provide precise spatiotemporal resolution. In this review, we highlight recent advances in visualizing protein associations and networks under increasingly native conditions. These advances include second generation protein complementation assays (PCAs), chemical and photo-crosslinking techniques, and proximity-induced ligation approaches. The advances described focus on background reduction, signal optimization, rapid and reversible reporter assembly, decreased cytotoxicity, and minimal functional perturbation. Key breakthroughs have addressed many challenges and should expand the repertoire of tools useful for generating maps of protein interactions resolved in both time and space. Copyright © 2011 Elsevier Ltd. All rights reserved.

Deep Generative Models of Galaxy Images for the Calibration of the Next Generation of Weak Lensing Surveys

NASA Astrophysics Data System (ADS)

Lanusse, Francois; Ravanbakhsh, Siamak; Mandelbaum, Rachel; Schneider, Jeff; Poczos, Barnabas

2017-01-01

Weak gravitational lensing has long been identified as one of the most powerful probes to investigate the nature of dark energy. As such, weak lensing is at the heart of the next generation of cosmological surveys such as LSST, Euclid or WFIRST.One particularly crititcal source of systematic errors in these surveys comes from the shape measurement algorithms tasked with estimating galaxy shapes. GREAT3, the last community challenge to assess the quality of state-of-the-art shape measurement algorithms has in particular demonstrated that all current methods are biased to various degrees and, more importantly, that these biases depend on the details of the galaxy morphologies. These biases can be measured and calibrated by generating mock observations where a known lensing signal has been introduced and comparing the resulting measurements to the ground-truth. Producing these mock observations however requires input galaxy images of higher resolution and S/N than the simulated survey, which typically implies acquiring extremely expensive space-based observations.The goal of this work is to train a deep generative model on already available Hubble Space Telescope data which can then be used to sample new galaxy images conditioned on parameters such as magnitude, size or redshift and exhibiting complex morphologies. Such model can allow us to inexpensively produce large set of realistic realistic images for calibration purposes.We implement a conditional generative model based on state-of-the-art deep learning methods and fit it to deep galaxy images from the COSMOS survey. The quality of the model is assessed by computing an extensive set of galaxy morphology statistics on the generated images. Beyond simple second moment statistics such as size and ellipticity, we apply more complex statistics specifically designed to be sensitive to disturbed galaxy morphologies. We find excellent agreement between the morphologies of real and model generated galaxies.Our results suggest that such deep generative models represent a reliable alternative to the acquisition of expensive high quality observations for generating the calibration data needed by the next generation of weak lensing surveys.

Space shuttle post-entry and landing analysis. Volume 2: Appendices

NASA Technical Reports Server (NTRS)

Crawford, B. S.; Duiven, E. M.

1973-01-01

Four candidate navigation systems for the space shuttle orbiter approach and landing phase are evaluated in detail. These include three conventional navaid systems and a single-station one-way Doppler system. In each case, a Kalman filter is assumed to be mechanized in the onboard computer, blending the navaid data with IMU and altimeter data. Filter state dimensions ranging from 6 to 24 are involved in the candidate systems. Comprehensive truth models with state dimensions ranging from 63 to 82 are formulated and used to generate detailed error budgets and sensitivity curves illustrating the effect of variations in the size of individual error sources on touchdown accuracy. The projected overall performance of each system is shown in the form of time histories of position and velocity error components.

Communication: Extended multi-state complete active space second-order perturbation theory: Energy and nuclear gradients

NASA Astrophysics Data System (ADS)

Shiozaki, Toru; Győrffy, Werner; Celani, Paolo; Werner, Hans-Joachim

2011-08-01

The extended multireference quasi-degenerate perturbation theory, proposed by Granovsky [J. Chem. Phys. 134, 214113 (2011)], is combined with internally contracted multi-state complete active space second-order perturbation theory (XMS-CASPT2). The first-order wavefunction is expanded in terms of the union of internally contracted basis functions generated from all the reference functions, which guarantees invariance of the theory with respect to unitary rotations of the reference functions. The method yields improved potentials in the vicinity of avoided crossings and conical intersections. The theory for computing nuclear energy gradients for MS-CASPT2 and XMS-CASPT2 is also presented and the first implementation of these gradient methods is reported. A number of illustrative applications of the new methods are presented.

Optimal control for wind turbine system via state-space method

NASA Astrophysics Data System (ADS)

Shanoob, Mudhafar L.

Renewable energy is becoming a fascinating research interest in future energy production because it is green and does not pollute nature. Wind energy is an excellent example of renewable resources that are evolving. Throughout the history of humanity, wind energy has been used. In ancient time, it was used to grind seeds, sailing etc. Nowadays, wind energy has been used to generate electrical power. Researchers have done a lot of research about using a wind source to generate electricity. As wind flow is not reliable, there is a challenge to get stable electricity out of this varying wind. This problem leads to the use of different control methods and the optimization of these methods to get a stable and reliable electrical energy. In this research, a wind turbine system is considered to study the transient and the steady-state stability; consisting of the aerodynamic system, drive train and generator. The Doubly Feed Induction Generator (DFIG) type generator is used in this thesis. The wind turbine system is connected to power system network. The grid is an infinite bus bar connected to a short transmission line and transformer. The generator is attached to the grid from the stator side. State-space method is used to model the wind turbine parts. The system is modeled and controlled using MATLAB/Simulation software. First, the current-mode control method (PVdq) with (PI) regulator is operated as a reference to find how the system reacts to an unexpected disturbance on the grid side or turbine side. The controller is operated with three scenarios of disruption: Disturbance-mechanical torque input, Step disturbance in the electrical torque reference and Fault Ride-through. In the simulation results, the time response and the transient stability of the system is a product of the disturbances that take a long time to settle. So, for this reason, Linear Quadratic Regulation (LQR) optimal control is utilized to solve this problem. The LQR method is designed based on using type 1 servo system that depends on the full state feedback variables and tracking error. The LQR improves the transient stability and time response of the wind turbine system in all three-disturbance scenarios. The results of both methods are deeply explained in the simulation section.

Space Shuttle: The Renewed Promise

NASA Technical Reports Server (NTRS)

McAleer, Neil

1989-01-01

NASA celebrated its 30th anniversary in 1988, two days after the Space Shuttle soared into space once more. When Congress approved the creation of the National Aeronautics and Space Administration in 1958, the United States had successfully launched only four small satellites and no American astronaut had yet flown in space. In the three decades since, four generations of manned spacecraft have been built and flown, twelve men have walked on the Moon, more than 100 Americans have flown and worked in space, and communications satellites and other Space-Age technologies have transformed life on planet Earth. When NASA's Golden Anniversary is celebrated in 2008, it is likely that men and women will be permanently living and working in space. There may be a base on the Moon, and a manned mission to Mars may only be years away. If a brief history of the first half-century of the Space Age is written for that event, it will show clearly how the exploration of space has altered the course of human history and allowed us to take a better hold of our destiny on and off planet Earth.

Efficient assessments of urban tree planting potential around the southern Piedmont region of the United States

Treesearch

Krista Merry; Jacek Siry; Pete Bettinger; Michael Bowker

2013-01-01

Urban forest carbon offset projects have the potential todraw substantial amounts ofcarbon dioxide (CO2) from the atmosphere ,increase green space,and possibly generate revenue for landowne rsincities capable of trading credits associated with these projects.The area of15cities inornear the Piedmont region of the southern...

Effects of Video Streaming Technology on Public Speaking Students' Communication Apprehension and Competence

ERIC Educational Resources Information Center

Dupagne, Michel; Stacks, Don W.; Giroux, Valerie Manno

2007-01-01

This study examines whether video streaming can reduce trait and state communication apprehension, as well as improve communication competence, in public speaking classes. Video streaming technology has been touted as the next generation of video feedback for public speaking students because it is not limited by time or space and allows Internet…

Learning across Space Instead of over Time: Redesigning a School-Based STEM Curriculum for OST

ERIC Educational Resources Information Center

Newbill, Phyllis Leary; Drape, Tiffany A.; Schnittka, Christine; Baum, Liesl; Evans, Michael A.

2015-01-01

Both employer expectations and education standards, including the Common Core State Standards and Next Generation Science Standards, are shifting the focus of learning from knowledge and discrete skills to the ability to think critically and creatively. This paper describes the process of translating an existing teacher-led STEM curriculum to fit…

When Schooling Becomes a Tactic of Security: Educating to Counter "Extremism"

ERIC Educational Resources Information Center

Shirazi, Roozbeh

2017-01-01

The intent of this series is to generate a space for critical reflection and inquiry on a burgeoning form of sociopolitical labor of schooling, that of educating against "extremism." In the United States' ongoing "War on Terror" being waged across the Middle East, North and East Africa, and South Asia, formal and informal…

Generating a Multiphase Equation of State with Swarm Intelligence

NASA Astrophysics Data System (ADS)

Cox, Geoffrey

2017-06-01

Hydrocode calculations require knowledge of the variation of pressure of a material with density and temperature, which is given by the equation of state. An accurate model needs to account for discontinuities in energy, density and properties of a material across a phase boundary. When generating a multiphase equation of state the modeller attempts to balance the agreement between the available data for compression, expansion and phase boundary location. However, this can prove difficult because minor adjustments in the equation of state for a single phase can have a large impact on the overall phase diagram. Recently, Cox and Christie described a method for combining statistical-mechanics-based condensed matter physics models with a stochastic analysis technique called particle swarm optimisation. The models produced show good agreement with experiment over a wide range of pressure-temperature space. This talk details the general implementation of this technique, shows example results, and describes the types of analysis that can be performed with this method.

Collective and non-collective structures in nuclei of mass region A ≈ 125

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

Singh, A. K.; Collaboration: INGA Collaboration; Gammasphere Collaboration

Generation of angular momentum in nuclei is a key question in nuclear structure studies. In single particle model, it is due to alignment of spin of individual nucleon available in the valence space, whereas coherent motion of nucleons are assumed in the collective model. The nuclei near the closed shell at Z = 50 with mass number A ≈ 120-125 represent ideal cases to explore the interplay between these competing mechanisms and the transition from non-collective to collective behavior or vice versa. Recent spectroscopic studies of nuclei in this region reveal several non-collective maximally aligned states representing the first kindmore » of excitation mechanism, where 8-12 particles above the {sup 114}Sn align their spins to generate these states. Deformed rotational bands feeding the non-collective states in the spin range I=20-25 and excitation energies around 10 MeV have also been observed. Structure of the collective and non-collective states are discussed in the framework of Cranked-Nilsson-Strutinsky model.« less

Analytical design of a parasitic-loading digital speed controller for a 400-hertz turbine driven alternator

NASA Technical Reports Server (NTRS)

Ingle, B. D.; Ryan, J. P.

1972-01-01

A design for a solid-state parasitic speed controller using digital logic was analyzed. Parasitic speed controllers are used in space power electrical generating systems to control the speed of turbine-driven alternators within specified limits. The analysis included the performance characteristics of the speed controller and the generation of timing functions. The speed controller using digital logic applies step loads to the alternator. The step loads conduct for a full half wave starting at either zero or 180 electrical degrees.

Control Scheme for Quickly Starting X-ray Tube

NASA Astrophysics Data System (ADS)

Nakahama, Masayuki; Nakanishi, Toshiki; Ishitobi, Manabu; Ito, Tuyoshi; Hosoda, Kenichi

A control scheme for quickly starting a portable X-ray generator used in the livestock industry is proposed in this paper. A portable X-ray generator used to take X-ray images of animals such as horses, sheep and dogs should be capable of starting quickly because it is difficult for veterinarians to take X-ray images of animals at their timing. In order to develop a scheme for starting the X-ray tube quickly, it is necessary to analysis the X-ray tube. However, such an analysis has not been discussed until now. First, the states of an X-ray tube are classified into the temperature-limited state and the space-charge-limited state. Furthermore, existence of “mixed state” that comprises both is newly proposed in this paper. From these analyses, a novel scheme for quickly starting an X-ray generator is proposed; this scheme is considered with the characteristics of the X-ray tube. The proposed X-ray system that is capable of starting quickly is evaluated on the basis of experimental results.

Free-space measurement-device-independent quantum-key-distribution protocol using decoy states with orbital angular momentum

NASA Astrophysics Data System (ADS)

Wang, Le; Zhao, Sheng-Mei; Gong, Long-Yan; Cheng, Wei-Wen

2015-12-01

In this paper, we propose a measurement-device-independent quantum-key-distribution (MDI-QKD) protocol using orbital angular momentum (OAM) in free space links, named the OAM-MDI-QKD protocol. In the proposed protocol, the OAM states of photons, instead of polarization states, are used as the information carriers to avoid the reference frame alignment, the decoy-state is adopted to overcome the security loophole caused by the weak coherent pulse source, and the high efficient OAM-sorter is adopted as the measurement tool for Charlie to obtain the output OAM state. Here, Charlie may be an untrusted third party. The results show that the authorized users, Alice and Bob, could distill a secret key with Charlie’s successful measurements, and the key generation performance is slightly better than that of the polarization-based MDI-QKD protocol in the two-dimensional OAM cases. Simultaneously, Alice and Bob can reduce the number of flipping the bits in the secure key distillation. It is indicated that a higher key generation rate performance could be obtained by a high dimensional OAM-MDI-QKD protocol because of the unlimited degree of freedom on OAM states. Moreover, the results show that the key generation rate and the transmission distance will decrease as the growth of the strength of atmospheric turbulence (AT) and the link attenuation. In addition, the decoy states used in the proposed protocol can get a considerable good performance without the need for an ideal source. Project supported by the National Natural Science Foundation of China (Grant Nos. 61271238 and 61475075), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20123223110003), the Natural Science Research Foundation for Universities of Jiangsu Province of China (Grant No. 11KJA510002), the Open Research Fund of Key Laboratory of Broadband Wireless Communication and Sensor Network Technology, Ministry of Education, China (Grant No. NYKL2015011), and the Innovation Program of Graduate Education of Jiangsu Province, China (Grant No. KYLX0810). Gong Long-Yan is partially supported by Qinglan Project of Jiangsu Province, China.

Cloud Physics Test in the Space Power Chamber

NASA Image and Video Library

1975-09-21

A researcher sets up equipment in the Space Power Chamber at National Aeronautics and Space Administration’s (NASA) Plum Brook Station to study the effects of contaminants on clouds. Drs. Rosa and Jorge Pena of Pennsylvania State University's Department of Meteorology initiated the program in an effort to develop methods of creating stable, long-lasting clouds in a test chamber in order to study their composition and formation. The researchers then wanted to use the artificially-created clouds to determine how they were affected by pollution. The 100-foot diameter and 122-foot high Space Power Chamber is the largest vacuum chamber in the world. The researchers covered the circular walls with muslin. A recirculating water system saturated the cloth. The facility engineers then reduced the chamber’s pressure which released the water from the muslin and generated a cloud. The researchers produced five different clouds in this first portion of this study. They discovered that they could not create stable clouds because of the heat generated by the water-pumping equipment. Nonetheless, they felt confident enough to commence planning the second phase of the program using a heat exchanger to cool the equipment.

Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

NASA Technical Reports Server (NTRS)

Vilnrotter, Victor A.

2012-01-01

The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

Results of the Simulation and Assimilation of Doppler Wind Lidar Observations in Preparation for European Space Agency's Aeolus Mission

NASA Technical Reports Server (NTRS)

McCarty, Will

2011-01-01

With the launch of the European Space Agency's Aeolus Mission in 2013, direct spaceborne measurements of vertical wind profiles are imminent via Doppler wind lidar technology. Part of the preparedness for such missions is the development of the proper data assimilation methodology for handling such observations. Since no heritage measurements exist in space, the Joint Observing System Simulation Experiment (Joint OSSE) framework has been utilized to generate a realistic proxy dataset as a precursor to flight. These data are being used for the development of the Gridpoint Statistical Interpolation (GSI) data assimilation system utilized at a number of centers through the United States including the Global Modeling and Assimilation Office (GMAO) at NASA/Goddard Space Flight Center and at the National Centers for Environmental Prediction (NOAA/NWS/NCEP) as an activity through the Joint Center for Satellite Data Assimilation. An update of this ongoing effort will be presented, including the methodology of proxy data generation, the limitations of the proxy data, the handling of line-of-sight wind measurements within the GSI, and the impact on both analyses and forecasts with the addition of the new data type.

Study of flywheel energy storage for space stations

NASA Technical Reports Server (NTRS)

Gross, S.

1984-01-01

The potential of flywheel systems for space stations using the Space Operations Center (SOC) as a point of reference is discussed. Comparisons with batteries and regenerative fuel cells are made. In the flywheel energy storage concept, energy is stored in the form of rotational kinetic energy using a spinning wheel. Energy is extracted from the flywheel using an attached electrical generator; energy is provided to spin the flywheel by a motor, which operates during sunlight using solar array power. The motor and the generator may or may not be the same device. Flywheel energy storage systems have a very good potential for use in space stations. This system can be superior to alkaline secondary batteries and regenerable fuel cells in most of the areas that are important in spacecraft applications. Of special impotance relative to batteries, are high energy density (lighter weight), longer cycle and operating life, and high efficiency which minimizes the amount of orbital makeup fuel required. In addition, flywheel systems have a long shelf life, give a precise state of charge indication, have modest thermal control needs, are capable of multiple discharges per orbit, have simple ground handling needs, and have the potential for very high discharge rate. Major disadvantages are noted.

Modeling of a solar-pumped iodine laser

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Lee, J. H.

1980-01-01

The direct conversion in space of solar radiation into laser radiation for power transmission to earth, satellites, or deep space probes shows promise as a reasonably simple technology and may have cost advantage in deployment and greater reliability compared to other methods of space power generation and transmission. The main candidates for solar pumping are the gas dynamic, photochemical, and direct photoexcited lasers. Here consideration is given to the photochemical reaction of alkyliodides which predominantly excite the I(2P1/2) state which then lases at 1.315 microns. The iodine ground state is eventually lost to reconstituting the gas or in the formation of molecular iodine. The rates at which the gas is required to be recycled through the laser system are modest. The side exposure at 100-fold solar concentration of a 100-m long tube with a 1 sq m cross section is estimated to provide 20 kW of continuous laser output. Scaling laws and optimum operating conditions of this system are discussed.

SAGE-III Ready for Ozone Checkup

NASA Image and Video Library

2017-02-15

A third-generation investigation into the state of the ozone layer of Earth’s atmosphere is scheduled for launch to the International Space Station on the SpaceX-10 cargo ship. Marilee Roell of NASA’s Langley Research Center explains how the third iteration of the Stratospheric Aerosol and Gas Experiment will measure ozone, aerosols and other components of the atmosphere for scientists who hope to see an improvement in the atmosphere’s ability to protect the planet—and everyone and everything on it—from harmful ultraviolet radiation. For more on ISS science, visit us online: https://www.nasa.gov/mission_pages/station/research/index.html www.twitter.com/iss_research HD download link: https://archive.org/details/TheSpaceProgram _______________________________________ FOLLOW THE SPACE STATION! Twitter: https://twitter.com/Space_Station Facebook: https://www.facebook.com/ISS Instagram: https://instagram.com/iss/ YouTube: https://youtu.be/HQdMZ5OAU3U

Practical system for the generation of pulsed quantum frequency combs.

PubMed

Roztocki, Piotr; Kues, Michael; Reimer, Christian; Wetzel, Benjamin; Sciara, Stefania; Zhang, Yanbing; Cino, Alfonso; Little, Brent E; Chu, Sai T; Moss, David J; Morandotti, Roberto

2017-08-07

The on-chip generation of large and complex optical quantum states will enable low-cost and accessible advances for quantum technologies, such as secure communications and quantum computation. Integrated frequency combs are on-chip light sources with a broad spectrum of evenly-spaced frequency modes, commonly generated by four-wave mixing in optically-excited nonlinear micro-cavities, whose recent use for quantum state generation has provided a solution for scalable and multi-mode quantum light sources. Pulsed quantum frequency combs are of particular interest, since they allow the generation of single-frequency-mode photons, required for scaling state complexity towards, e.g., multi-photon states, and for quantum information applications. However, generation schemes for such pulsed combs have, to date, relied on micro-cavity excitation via lasers external to the sources, being neither versatile nor power-efficient, and impractical for scalable realizations of quantum technologies. Here, we introduce an actively-modulated, nested-cavity configuration that exploits the resonance pass-band characteristic of the micro-cavity to enable a mode-locked and energy-efficient excitation. We demonstrate that the scheme allows the generation of high-purity photons at large coincidence-to-accidental ratios (CAR). Furthermore, by increasing the repetition rate of the excitation field via harmonic mode-locking (i.e. driving the cavity modulation at harmonics of the fundamental repetition rate), we managed to increase the pair production rates (i.e. source efficiency), while maintaining a high CAR and photon purity. Our approach represents a significant step towards the realization of fully on-chip, stable, and versatile sources of pulsed quantum frequency combs, crucial for the development of accessible quantum technologies.

De Sitter Space Without Dynamical Quantum Fluctuations

NASA Astrophysics Data System (ADS)

Boddy, Kimberly K.; Carroll, Sean M.; Pollack, Jason

2016-06-01

We argue that, under certain plausible assumptions, de Sitter space settles into a quiescent vacuum in which there are no dynamical quantum fluctuations. Such fluctuations require either an evolving microstate, or time-dependent histories of out-of-equilibrium recording devices, which we argue are absent in stationary states. For a massive scalar field in a fixed de Sitter background, the cosmic no-hair theorem implies that the state of the patch approaches the vacuum, where there are no fluctuations. We argue that an analogous conclusion holds whenever a patch of de Sitter is embedded in a larger theory with an infinite-dimensional Hilbert space, including semiclassical quantum gravity with false vacua or complementarity in theories with at least one Minkowski vacuum. This reasoning provides an escape from the Boltzmann brain problem in such theories. It also implies that vacuum states do not uptunnel to higher-energy vacua and that perturbations do not decohere while slow-roll inflation occurs, suggesting that eternal inflation is much less common than often supposed. On the other hand, if a de Sitter patch is a closed system with a finite-dimensional Hilbert space, there will be Poincaré recurrences and dynamical Boltzmann fluctuations into lower-entropy states. Our analysis does not alter the conventional understanding of the origin of density fluctuations from primordial inflation, since reheating naturally generates a high-entropy environment and leads to decoherence, nor does it affect the existence of non-dynamical vacuum fluctuations such as those that give rise to the Casimir effect.

NASA Performance Report

NASA Technical Reports Server (NTRS)

2000-01-01

Introduction NASA's mission is to advance and communicate scientific knowledge and understanding of Earth, the solar system, and the universe; to advance human exploration, use, and development of space; and to research, develop, verify, and transfer advanced aeronautics, space, and related technologies. In support of this mission, NASA has a strategic architecture that consists of four Enterprises supported by four Crosscutting Processes. The Strategic Enterprises are NASA's primary mission areas to include Earth Science, Space Science, Human Exploration and Development of Space, and Aerospace Technology. NASA's Crosscutting Processes are Manage Strategically, Provide Aerospace Products and Capabilities, Generate Knowledge and Communicate Knowledge. The implementation of NASA programs, science, and technology research occurs primarily at our Centers. NASA consists of a Headquarters, nine Centers, and the Jet Propulsion Laboratory, as well as several ancillary installations and offices in the United States and abroad. The nine Centers are as follows: (1) Ames Research Center, (2) Dryden Flight Research Center (DFRC), (3) Glenn Research Center (GRC), (4) Goddard Space Flight Center (GSFC), (5) Johnson Space Center, (6) Kennedy Space Center (KSC), (7) Langley Research Center (LaRC), (8) Marshall Space Flight Center (MSFC), and (9) Stennis Space Center (SSC).

Simple procedure for phase-space measurement and entanglement validation

NASA Astrophysics Data System (ADS)

Rundle, R. P.; Mills, P. W.; Tilma, Todd; Samson, J. H.; Everitt, M. J.

2017-08-01

It has recently been shown that it is possible to represent the complete quantum state of any system as a phase-space quasiprobability distribution (Wigner function) [Phys. Rev. Lett. 117, 180401 (2016), 10.1103/PhysRevLett.117.180401]. Such functions take the form of expectation values of an observable that has a direct analogy to displaced parity operators. In this work we give a procedure for the measurement of the Wigner function that should be applicable to any quantum system. We have applied our procedure to IBM's Quantum Experience five-qubit quantum processor to demonstrate that we can measure and generate the Wigner functions of two different Bell states as well as the five-qubit Greenberger-Horne-Zeilinger state. Because Wigner functions for spin systems are not unique, we define, compare, and contrast two distinct examples. We show how the use of these Wigner functions leads to an optimal method for quantum state analysis especially in the situation where specific characteristic features are of particular interest (such as for spin Schrödinger cat states). Furthermore we show that this analysis leads to straightforward, and potentially very efficient, entanglement test and state characterization methods.

Real-Space Mapping of Surface Trap States in CIGSe Nanocrystals Using 4D Electron Microscopy.

PubMed

Bose, Riya; Bera, Ashok; Parida, Manas R; Adhikari, Aniruddha; Shaheen, Basamat S; Alarousu, Erkki; Sun, Jingya; Wu, Tom; Bakr, Osman M; Mohammed, Omar F

2016-07-13

Surface trap states in copper indium gallium selenide semiconductor nanocrystals (NCs), which serve as undesirable channels for nonradiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with subpicosecond temporal and nanometer spatial resolutions. Here, we precisely map the collective surface charge carrier dynamics of copper indium gallium selenide NCs as a function of the surface trap states before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, the removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

Genetic Algorithm-Based Model Order Reduction of Aeroservoelastic Systems with Consistant States

NASA Technical Reports Server (NTRS)

Zhu, Jin; Wang, Yi; Pant, Kapil; Suh, Peter M.; Brenner, Martin J.

2017-01-01

This paper presents a model order reduction framework to construct linear parameter-varying reduced-order models of flexible aircraft for aeroservoelasticity analysis and control synthesis in broad two-dimensional flight parameter space. Genetic algorithms are used to automatically determine physical states for reduction and to generate reduced-order models at grid points within parameter space while minimizing the trial-and-error process. In addition, balanced truncation for unstable systems is used in conjunction with the congruence transformation technique to achieve locally optimal realization and weak fulfillment of state consistency across the entire parameter space. Therefore, aeroservoelasticity reduced-order models at any flight condition can be obtained simply through model interpolation. The methodology is applied to the pitch-plant model of the X-56A Multi-Use Technology Testbed currently being tested at NASA Armstrong Flight Research Center for flutter suppression and gust load alleviation. The present studies indicate that the reduced-order model with more than 12× reduction in the number of states relative to the original model is able to accurately predict system response among all input-output channels. The genetic-algorithm-guided approach exceeds manual and empirical state selection in terms of efficiency and accuracy. The interpolated aeroservoelasticity reduced order models exhibit smooth pole transition and continuously varying gains along a set of prescribed flight conditions, which verifies consistent state representation obtained by congruence transformation. The present model order reduction framework can be used by control engineers for robust aeroservoelasticity controller synthesis and novel vehicle design.

sts088-s-001

NASA Image and Video Library

1998-09-01

STS088-S-001 (September 1998) --- Designed by the crew members, this STS-88 patch commemorates the first assembly flight to carry United States-built hardware for constructing the International Space Station (ISS). This flight's primary task is to assemble the cornerstone of the space station: the Node with the Functional Cargo Block (FGB). The rising sun symbolizes the dawning of a new era of international cooperation in space and the beginning of a new program: the International Space Station. The Earth scene outlines the countries of the Station Partners: the United States, Russia, those of the European Space Agency (ESA), Japan, and Canada. Along with the Pressurized Mating Adapters (PMA) and the Functional Cargo Block, the Node is shown in the final mated configuration while berthed to the space shuttle during the STS-88/2A mission. The Big Dipper Constellation points the way to the North Star, a guiding light for pioneers and explorers for generations. In the words of the crew, "These stars symbolize the efforts of everyone, including all the countries involved in the design and construction of the International Space Station, guiding us into the future." The NASA insignia design for space shuttle flights is reserved for use by the astronauts and for other official use as the NASA Administrator may authorize. Public availability has been approved only in the forms of illustrations by the various news media. When and if there is any change in this policy, which is not anticipated, the change will be publicly announced. Photo credit: NASA

Theoretical study of singlet oxygen molecule generation via an exciplex with valence-excited thiophene.

PubMed

Sumita, Masato; Morihashi, Kenji

2015-02-05

Singlet-oxygen [O2((1)Δg)] generation by valence-excited thiophene (TPH) has been investigated using multireference Møller-Plesset second-order perturbation (MRMP2) theory of geometries optimized at the complete active space self-consistent field (CASSCF) theory level. Our results indicate that triplet TPH(1(3)B2) is produced via photoinduced singlet TPH(2(1)A1) because 2(1)A1 TPH shows a large spin-orbit coupling constant with the first triplet excited state (1(3)B2). The relaxed TPH in the 1(3)B2 state can form an exciplex with O2((3)Σg(-)) because this exciplex is energetically more stable than the relaxed TPH. The formation of the TPH(1(3)B2) exciplex with O2((3)Σg(-)) whose total spin multiplicity is triplet (T1 state) increases the likelihood of transition from the T1 state to the singlet ground or first excited singlet state. After the transition, O2((1)Δg) is emitted easily although the favorable product is that from a 2 + 4 cycloaddition reaction.

Abstract Interpreters for Free

NASA Astrophysics Data System (ADS)

Might, Matthew

In small-step abstract interpretations, the concrete and abstract semantics bear an uncanny resemblance. In this work, we present an analysis-design methodology that both explains and exploits that resemblance. Specifically, we present a two-step method to convert a small-step concrete semantics into a family of sound, computable abstract interpretations. The first step re-factors the concrete state-space to eliminate recursive structure; this refactoring of the state-space simultaneously determines a store-passing-style transformation on the underlying concrete semantics. The second step uses inference rules to generate an abstract state-space and a Galois connection simultaneously. The Galois connection allows the calculation of the "optimal" abstract interpretation. The two-step process is unambiguous, but nondeterministic: at each step, analysis designers face choices. Some of these choices ultimately influence properties such as flow-, field- and context-sensitivity. Thus, under the method, we can give the emergence of these properties a graph-theoretic characterization. To illustrate the method, we systematically abstract the continuation-passing style lambda calculus to arrive at two distinct families of analyses. The first is the well-known k-CFA family of analyses. The second consists of novel "environment-centric" abstract interpretations, none of which appear in the literature on static analysis of higher-order programs.

Sensitivity of Attitude Determination on the Model Assumed for ISAR Radar Mappings

NASA Astrophysics Data System (ADS)

Lemmens, S.; Krag, H.

2013-09-01

Inverse synthetic aperture radars (ISAR) are valuable instrumentations for assessing the state of a large object in low Earth orbit. The images generated by these radars can reach a sufficient quality to be used during launch support or contingency operations, e.g. for confirming the deployment of structures, determining the structural integrity, or analysing the dynamic behaviour of an object. However, the direct interpretation of ISAR images can be a demanding task due to the nature of the range-Doppler space in which these images are produced. Recently, a tool has been developed by the European Space Agency's Space Debris Office to generate radar mappings of a target in orbit. Such mappings are a 3D-model based simulation of how an ideal ISAR image would be generated by a ground based radar under given processing conditions. These radar mappings can be used to support a data interpretation process. E.g. by processing predefined attitude scenarios during an observation sequence and comparing them with actual observations, one can detect non-nominal behaviour. Vice versa, one can also estimate the attitude states of the target by fitting the radar mappings to the observations. It has been demonstrated for the latter use case that a coarse approximation of the target through an 3D-model is already sufficient to derive the attitude information from the generated mappings. The level of detail required for the 3D-model is determined by the process of generating ISAR images, which is based on the theory of scattering bodies. Therefore, a complex surface can return an intrinsically noisy ISAR image. E.g. when many instruments on a satellite are visible to the observer, the ISAR image can suffer from multipath reflections. In this paper, we will further analyse the sensitivity of the attitude fitting algorithms to variations in the dimensions and the level of detail of the underlying 3D model. Moreover, we investigate the ability to estimate the orientations of different spacecraft components with respect to each other from the fitting procedure.

Three-dimensional vectorial multifocal arrays created by pseudo-period encoding

NASA Astrophysics Data System (ADS)

Zeng, Tingting; Chang, Chenliang; Chen, Zhaozhong; Wang, Hui-Tian; Ding, Jianping

2018-06-01

Multifocal arrays have been attracting considerable attention recently owing to their potential applications in parallel optical tweezers, parallel single-molecule orientation determination, parallel recording and multifocal multiphoton microscopy. However, the generation of vectorial multifocal arrays with a tailorable structure and polarization state remains a great challenge, and reports on multifocal arrays have hitherto been restricted either to scalar focal spots without polarization versatility or to regular arrays with fixed spacing. In this work, we propose a specific pseudo-period encoding technique to create three-dimensional (3D) vectorial multifocal arrays with the ability to manipulate the position, polarization state and intensity of each focal spot. We experimentally validated the flexibility of our approach in the generation of 3D vectorial multiple spots with polarization multiplicity and position tunability.

Enabling Future Science and Human Exploration with NASA's Next Generation Near Earth and Deep Space Communications and Navigation Architecture

NASA Technical Reports Server (NTRS)

Reinhart, Richard; Schier, James; Israel, David; Tai, Wallace; Liebrecht, Philip; Townes, Stephen

2017-01-01

The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities to meet unique space environment requirements and to provide capabilities that are beyond the commercial marketplace. The progress of the communications industry, including the emerging global space internet segment and its planned constellations of 100's of satellites offer additional opportunities for new capability and mission concepts. The opportunities and challenges of a future space architecture require an optimal solution encompassing a global perspective. The concepts and technologies intentionally define an architecture that applies not only to NASA, but to other U.S. government agencies, international space and government agencies, and domestic and international industries to advance the openness, interoperability, and affordability of space communications. Cooperation among the worlds space agencies, their capabilities, standards, operations, and interoperability are key to advancing humankinds understand of the universe and extending human presence into the solar system.

Enabling Future Science and Human Exploration with NASA's Next Generation near Earth and Deep Space Communications and Navigation Architecture

NASA Technical Reports Server (NTRS)

Reinhart, Richard C.; Schier, James S.; Israel, David J.; Tai, Wallace; Liebrecht, Philip E.; Townes, Stephen A.

2017-01-01

The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities to meet unique space environment requirements and to provide capabilities that are beyond the commercial marketplace. The progress of the communications industry, including the emerging global space internet segment and its planned constellations of 100's of satellites offer additional opportunities for new capability and mission concepts. The opportunities and challenges of a future space architecture require an optimal solution encompassing a global perspective. The concepts and technologies intentionally define an architecture that applies not only to NASA, but to other U.S. government agencies, international space and government agencies, and domestic and international industries to advance the openness, interoperability, and affordability of space communications. Cooperation among the worlds space agencies, their capabilities, standards, operations, and interoperability are key to advancing humankind's understand of the universe and extending human presence into the solar system.

Materials technology programs in support of a mercury Rankine space power system

NASA Technical Reports Server (NTRS)

Stone, P. L.

1973-01-01

A large portion of the materials technology is summarized that was generated in support of the development of a mercury-rankine space power system (SNAP-8). The primary areas of investigation are: (1) the compatibility of various construction materials with the liquid metals mercury and NaK, (2) the mechanical properties of unalloyed tantalum, and (3) the development of refractory metal/austenitic stainless steel tubing and transition joints. The primary results, conclusions, and state of technology at the completion of this effort for each of these areas are summarized. Results of possible significance to other applications are highlighted.

Trajectory Design Strategies for the NGST L2 Libration Point Mission

NASA Technical Reports Server (NTRS)

Folta, David; Cooley, Steven; Howell, Kathleen; Bauer, Frank H.

2001-01-01

The Origins' Next Generation Space Telescope (NGST) trajectory design is addressed in light of improved methods for attaining constrained orbit parameters and their control at the exterior collinear libration point, L2. The use of a dynamical systems approach, state-space equations for initial libration orbit control, and optimization to achieve constrained orbit parameters are emphasized. The NGST trajectory design encompasses a direct transfer and orbit maintenance under a constant acceleration. A dynamical systems approach can be used to provide a biased orbit and stationkeeping maintenance method that incorporates the constraint of a single axis correction scheme.

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

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

The next 25 years: Industrialization of space: Rationale for planning

NASA Technical Reports Server (NTRS)

Vonputtkamer, J.

1976-01-01

The goals of NASA's space industralization program include contributing to increased productivity on earth without taxing the environment, generating new values through extraterrestrial productivity, and providing new growth options for the future which include the permanent settlement of space and long-range colonization and exploration projects. In planning the long-range space program based on essentially utilitarian aspects, without losing sight of the more humanistically significant long term, and to forecast associated technology requirements, a realistic approach is obtained by combining extrapolative and normative planning modes so that common stepping stones can be identified. In the extrapolative view, alternative futures are projected on the basis of past and current trends and tendencies. In the normative view, some ideal state in the far future is envisioned or postulated, and policies and decisions are directed toward its attainment.

Space Monitoring Data Center at Moscow State University

NASA Astrophysics Data System (ADS)

Kalegaev, Vladimir; Bobrovnikov, Sergey; Barinova, Vera; Myagkova, Irina; Shugay, Yulia; Barinov, Oleg; Dolenko, Sergey; Mukhametdinova, Ludmila; Shiroky, Vladimir

Space monitoring data center of Moscow State University provides operational information on radiation state of the near-Earth space. Internet portal http://swx.sinp.msu.ru/ gives access to the actual data characterizing the level of solar activity, geomagnetic and radiation conditions in the magnetosphere and heliosphere in the real time mode. Operational data coming from space missions (ACE, GOES, ELECTRO-L1, Meteor-M1) at L1, LEO and GEO and from the Earth’s surface are used to represent geomagnetic and radiation state of near-Earth environment. On-line database of measurements is also maintained to allow quick comparison between current conditions and conditions experienced in the past. The models of space environment working in autonomous mode are used to generalize the information obtained from observations on the whole magnetosphere. Interactive applications and operational forecasting services are created on the base of these models. They automatically generate alerts on particle fluxes enhancements above the threshold values, both for SEP and relativistic electrons using data from LEO orbits. Special forecasting services give short-term forecast of SEP penetration to the Earth magnetosphere at low altitudes, as well as relativistic electron fluxes at GEO. Velocities of recurrent high speed solar wind streams on the Earth orbit are predicted with advance time of 3-4 days on the basis of automatic estimation of the coronal hole areas detected on the images of the Sun received from the SDO satellite. By means of neural network approach, Dst and Kp indices online forecasting 0.5-1.5 hours ahead, depending on solar wind and the interplanetary magnetic field, measured by ACE satellite, is carried out. Visualization system allows representing experimental and modeling data in 2D and 3D.

Extended Kinship in the United States: Competing Models and the Case of La Familia Chicana.

ERIC Educational Resources Information Center

Sena-Rivera, Jaime

1979-01-01

Extended kinship among Chicanos is explored through intensive open-ended interviews with four cases of three generations of Mexican-descent families. "La familia chicana" is posited as a modified extended or kin-integrated family extending over time and space from Mexico at the turn of the century to present day industrial America. (Author)

Degrees of Consciousness in the Communication of Actions and Events on the Visual Cliff. No. 58.

ERIC Educational Resources Information Center

Bierschenk, Bernhard

The consciousness of dizygotic twins in their communication of actions and events as seen in the visual cliff pictures published by E. J. Gibson and R. D. Walk (1960) was studied in Sweden. In the process of communication, many different state spaces are generated. The methodology demonstrates that ecological and biophysical properties of language…

Next Generation Advanced Video Guidance Sensor

NASA Technical Reports Server (NTRS)

Lee, Jimmy; Spencer, Susan; Bryan, Tom; Johnson, Jimmie; Robertson, Bryan

2008-01-01

The first autonomous rendezvous and docking in the history of the U.S. Space Program was successfully accomplished by Orbital Express, using the Advanced Video Guidance Sensor (AVGS) as the primary docking sensor. The United States now has a mature and flight proven sensor technology for supporting Crew Exploration Vehicles (CEV) and Commercial Orbital Transport. Systems (COTS) Automated Rendezvous and Docking (AR&D). AVGS has a proven pedigree, based on extensive ground testing and flight demonstrations. The AVGS on the Demonstration of Autonomous Rendezvous Technology (DART)mission operated successfully in "spot mode" out to 2 km. The first generation rendezvous and docking sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on Space Shuttle flights in 1997 and 1998. Parts obsolescence issues prevent the construction of more AVGS. units, and the next generation sensor must be updated to support the CEV and COTS programs. The flight proven AR&D sensor is being redesigned to update parts and add additional. capabilities for CEV and COTS with the development of the Next, Generation AVGS (NGAVGS) at the Marshall Space Flight Center. The obsolete imager and processor are being replaced with new radiation tolerant parts. In addition, new capabilities might include greater sensor range, auto ranging, and real-time video output. This paper presents an approach to sensor hardware trades, use of highly integrated laser components, and addresses the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS) and other Constellation vehicles. It will also discuss approaches for upgrading AVGS to address parts obsolescence, and concepts for minimizing the sensor footprint, weight, and power requirements. In addition, parts selection and test plans for the NGAVGS will be addressed to provide a highly reliable flight qualified sensor. Expanded capabilities through innovative use of existing capabilities will also be discussed.

Theoretical investigation of the generation and injection of electromagnetic waves in space plasma by means of a long-orbiting tether

NASA Technical Reports Server (NTRS)

Dobrowolny, M.

1981-01-01

Analysis of the various mechanisms of electromagnetic wave generation by the shuttle-borne orbiting tether of the T.S.S. Facility shows that significant electrodynamic power levels are available even when overestimating the loss mechanisms expected to intervene. This electrodynamic power is in part dissipated by Joule losses in the tether, in part goes to accelerate electrons through the sheath surrounding the balloon (when in a downward deployment), and in part goes into e.m. wave generation. A preliminary estimate shows that a 100 km tether in orbit would produce ULF/ELF signals that are detectable on the ground with state-of-the-art magnetometric instrumentation.

Automated event generation for loop-induced processes

DOE PAGES

Hirschi, Valentin; Mattelaer, Olivier

2015-10-22

We present the first fully automated implementation of cross-section computation and event generation for loop-induced processes. This work is integrated in the MadGraph5_aMC@NLO framework. We describe the optimisations implemented at the level of the matrix element evaluation, phase space integration and event generation allowing for the simulation of large multiplicity loop-induced processes. Along with some selected differential observables, we illustrate our results with a table showing inclusive cross-sections for all loop-induced hadronic scattering processes with up to three final states in the SM as well as for some relevant 2 → 4 processes. Furthermore, many of these are computed heremore » for the first time.« less

Brainstorming Design for Health: Helping Patients Utilize Patient-Generated Information on the Web

PubMed Central

Huh, Jina; Hartzler, Andrea; Munson, Sean; Anderson, Nick; Edwards, Kelly; Gore, John L.; McDonald, David; O’Leary, Jim; Parker, Andrea; Streat, Derek; Yetisgen-Yildiz, Meliha; Pratt, Wanda; Ackerman, Mark S.

2013-01-01

Researchers and practitioners show increasing sinterest in utilizing patient-generated information on the Web. Although the HCI and CSCW communities have provided many exciting opportunities for exploring new ideas and building broad agenda in health, few venues offer a platform for interdisciplinary and collaborative brainstorming about design challenges and opportunities in this space. The goal of this workshop is to provide participants with opportunities to interact with stakeholders from diverse backgrounds and practices—researchers, practitioners, designers, programmers, and ethnographers—and together generate tangible design outcomes that utilize patient-generated information on the Web. Through small multidisciplinary group work, we will provide participants with new collaboration opportunities, understanding of the state of the art, inspiration for future work, and ideally avenues for continuing to develop research and design ideas generated at the workshop. PMID:24499843

A methodology for the generation of the 2-D map from unknown navigation environment by traveling a short distance

NASA Technical Reports Server (NTRS)

Bourbakis, N.; Sarkar, D.

1994-01-01

A technique for generation of a 2-D space map by traveling a short distance is described. The space to be mapped can be classified as: (1) space without obstacles, (2) space with stationary obstacles, and (3) space with moving obstacles. This paper presents the methodology used to generate a 2-D map of an unknown navigation space. The ability to minimize the redundancy during traveling and maximize the confidence function for generation of the map are advantages of this technique.

Perspectives of The Interagency Nuclear Safety Review Panel (INSRP) on future nuclear powered space missions

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

Gray, L.B.; Pyatt, D.W.; Sholtis, J.A.

1993-01-10

The Interagency Nuclear Safety Review Panel (INSRP) has provided reviews of all nuclear powered spacecraft launched by the United States. The two most recent launches were Ulysses in 1990 and Galileo in 1989. One reactor was launched in 1965 (SNAP-10A). All other U.S. space missions have utilized radioisotopic thermoelectric generators (RTGs). There are several missions in the next few years that are to be nuclear powered, including one that would utilize the Topaz II reactor purchased from Russia. INSRP must realign itself to perform parallel safety assessments of a reactor powered space mission, which has not been done in aboutmore » thirty years, and RTG powered missions.« less

Population trapping in the excited states using vacuum-induced coherence and adiabatic process

NASA Astrophysics Data System (ADS)

Lal Kumawat, Babu; Kumar, Pardeep; Dasgupta, Shubhrangshu

2018-02-01

We theoretically investigate how population can be trapped in the closely spaced excited levels in presence of vacuum-induced coherence (VIC). We employ delayed pulses to transfer population from a meta-stable state to the excited states. Subsequently, spontaneous emission from these excited states builds coherence between them. This coherence can be probed by using chirping, which leads to the decoupling of the excited states from the ground state thereby ensuring population transfer via delayed pulses. Our results indicate that the existence of VIC leads to the generation of a mixed state in the excited state manifold, where trapping of the population occurs even in the presence of large decay. This trapping may be realized in molecular systems and can be interpreted as a sensitive probe of VIC. We present suitable numerical analysis to support our results.

Observation of Polarization Vortices in Momentum Space

NASA Astrophysics Data System (ADS)

Zhang, Yiwen; Chen, Ang; Liu, Wenzhe; Hsu, Chia Wei; Wang, Bo; Guan, Fang; Liu, Xiaohan; Shi, Lei; Lu, Ling; Zi, Jian

2018-05-01

The vortex, a fundamental topological excitation featuring the in-plane winding of a vector field, is important in various areas such as fluid dynamics, liquid crystals, and superconductors. Although commonly existing in nature, vortices were observed exclusively in real space. Here, we experimentally observed momentum-space vortices as the winding of far-field polarization vectors in the first Brillouin zone of periodic plasmonic structures. Using homemade polarization-resolved momentum-space imaging spectroscopy, we mapped out the dispersion, lifetime, and polarization of all radiative states at the visible wavelengths. The momentum-space vortices were experimentally identified by their winding patterns in the polarization-resolved isofrequency contours and their diverging radiative quality factors. Such polarization vortices can exist robustly on any periodic systems of vectorial fields, while they are not captured by the existing topological band theory developed for scalar fields. Our work provides a new way for designing high-Q plasmonic resonances, generating vector beams, and studying topological photonics in the momentum space.

Observation of Polarization Vortices in Momentum Space.

PubMed

Zhang, Yiwen; Chen, Ang; Liu, Wenzhe; Hsu, Chia Wei; Wang, Bo; Guan, Fang; Liu, Xiaohan; Shi, Lei; Lu, Ling; Zi, Jian

2018-05-04

The vortex, a fundamental topological excitation featuring the in-plane winding of a vector field, is important in various areas such as fluid dynamics, liquid crystals, and superconductors. Although commonly existing in nature, vortices were observed exclusively in real space. Here, we experimentally observed momentum-space vortices as the winding of far-field polarization vectors in the first Brillouin zone of periodic plasmonic structures. Using homemade polarization-resolved momentum-space imaging spectroscopy, we mapped out the dispersion, lifetime, and polarization of all radiative states at the visible wavelengths. The momentum-space vortices were experimentally identified by their winding patterns in the polarization-resolved isofrequency contours and their diverging radiative quality factors. Such polarization vortices can exist robustly on any periodic systems of vectorial fields, while they are not captured by the existing topological band theory developed for scalar fields. Our work provides a new way for designing high-Q plasmonic resonances, generating vector beams, and studying topological photonics in the momentum space.

KSC-2014-3922

NASA Image and Video Library

2014-09-16

KSC-2014-3922 - CAPE CANAVERAL, Fla. – Former astronaut Bob Cabana, center, director of NASA's Kennedy Space Center in Florida, speaks at the start of the announcement ceremony to name the providers of the next generation of crewed American spacecraft. Speaking from Kennedy’s Press Site, Cabana detailed the importance of the development effort by the agency's Commercial Crew Program for United States space exploration ambitions and the economic potential of creating new markets in human space transportation. Boeing and SpaceX were awarded contracts to complete the design of the CST-100 and Crew Dragon spacecraft, respectively, and begin manufacturing for flight tests with a goal of achieving certification to take astronauts to the International Space Station by 2017. The Commercial Crew Transportation Capability CCtCap contract also covers the beginning of operational missions for these new spacecraft and their systems. NASA spokeswoman Stephanie Schierholz, from left, Charles Bolden, NASA administrator, Kathy Lueders, manager of the agency's Commercial Crew Program, and former International Space Station Commander Mike Fincke also took part in the announcement. Photo credit: NASA/Jim Grossmann

Multi-Disciplinary Knowledge Synthesis for Human Health Assessment on Earth and in Space

NASA Astrophysics Data System (ADS)

Christakos, G.

We discuss methodological developments in multi-disciplinary knowledge synthesis (KS) of human health assessment. A theoretical KS framework can provide the rational means for the assimilation of various information bases (general, site-specific etc.) that are relevant to the life system of interest. KS-based techniques produce a realistic representation of the system, provide a rigorous assessment of the uncertainty sources, and generate informative health state predictions across space-time. The underlying epistemic cognition methodology is based on teleologic criteria and stochastic logic principles. The mathematics of KS involves a powerful and versatile spatiotemporal random field model that accounts rigorously for the uncertainty features of the life system and imposes no restriction on the shape of the probability distributions or the form of the predictors. KS theory is instrumental in understanding natural heterogeneities, assessing crucial human exposure correlations and laws of physical change, and explaining toxicokinetic mechanisms and dependencies in a spatiotemporal life system domain. It is hoped that a better understanding of KS fundamentals would generate multi-disciplinary models that are useful for the maintenance of human health on Earth and in Space.

Transient and Steady-state Tests of the Space Power Research Engine with Resistive and Motor Loads

NASA Technical Reports Server (NTRS)

Rauch, Jeffrey S.; Kankam, M. David

1995-01-01

The NASA Lewis Research Center (LeRC) has been testing free-piston Stirling engine/linear alternators (FPSE/LA) to develop advanced power convertors for space-based electrical power generation. Tests reported herein were performed to evaluate the interaction and transient behavior of FPSE/LA-based power systems with typical user loads. Both resistive and small induction motor loads were tested with the space power research engine (SPRE) power system. Tests showed that the control system could maintain constant long term voltage and stable periodic operation over a large range of engine operating parameters and loads. Modest resistive load changes were shown to cause relatively large voltage and, therefore, piston and displacer amplitude excursions. Starting a typical small induction motor was shown to cause large and, in some cases, deleterious voltage transients. The tests identified the need for more effective controls, if FPSE/LAs are to be used for stand-alone power systems. The tests also generated a large body of transient dynamic data useful for analysis code validation.

Transient and steady-state tests of the space power research engine with resistive and motor loads

NASA Astrophysics Data System (ADS)

Rauch, Jeffrey S.; Kankam, M. David

1995-01-01

The NASA Lewis Research Center (LeRC) has been testing free-piston Stirling engine/linear alternators (FPSE/LA) to develop advanced power convertors for space-based electrical power generation. Tests reported herein were performed to evaluate the interaction and transient behavior of FPSE/LA-based power systems with typical user loads. Both resistive and small induction motor loads were tested with the space power research engine (SPRE) power system. Tests showed that the control system could maintain constant long term voltage and stable periodic operation over a large range of engine operating parameters and loads. Modest resistive load changes were shown to cause relatively large voltage and, therefore, piston and displacer amplitude excursions. Starting a typical small induction motor was shown to cause large and, in some cases, deleterious voltage transients. The tests identified the need for more effective controls, if FPSE/LAs are to be used for stand-alone power systems. The tests also generated a large body of transient dynamic data useful for analysis code validation.

Implications of the Next Generation Science Standards for Earth and Space Sciences

NASA Astrophysics Data System (ADS)

Wysession, M. E.; Colson, M.; Duschl, R. A.; Huff, K.; Lopez, R. E.; Messina, P.; Speranza, P.; Matthews, T.; Childress, J.

2012-12-01

The Next Generation Science Standards (NGSS), due to be released in 2013, set a new direction for K-12 science education in America. These standards will put forth significant changes for Earth and space sciences. The NGSS are based upon the recommendations of the National Research Council's 2011 report "A Framework for K-12 Science Education: Practices, Cross-Cutting Concepts, and Core Ideas." The standards are being written by a large group of authors who represent many different constituencies, including 26 participating states, in a process led by Achieve, Inc. The standards encourage innovative ways to teach science at the K-12 level, including enhanced integration between the content, practices, and crosscutting ideas of science and greater assimilation among the sciences and engineering, and among the sciences, mathematics, and English language arts. The NGSS presents a greater emphasis on Earth and space sciences than in previous standards, recommending a year at both the middle and high school levels. The new standards also present a greater emphasis on areas of direct impact between humans and the Earth system, including climate change, natural hazards, resource management, and sustainability.

Cyber Security for the Spaceport Command and Control System: Vulnerability Management and Compliance Analysis

NASA Technical Reports Server (NTRS)

Gunawan, Ryan A.

2016-01-01

With the rapid development of the Internet, the number of malicious threats to organizations is continually increasing. In June of 2015, the United States Office of Personnel Management (OPM) had a data breach resulting in the compromise of millions of government employee records. The National Aeronautics and Space Administration (NASA) is not exempt from these attacks. Cyber security is becoming a critical facet to the discussion of moving forward with projects. The Spaceport Command and Control System (SCCS) project at the Kennedy Space Center (KSC) aims to develop the launch control system for the next generation launch vehicle in the coming decades. There are many ways to increase the security of the network it uses, from vulnerability management to ensuring operating system images are compliant with securely configured baselines recommended by the United States Government.

Parameter reduction in nonlinear state-space identification of hysteresis

NASA Astrophysics Data System (ADS)

Fakhrizadeh Esfahani, Alireza; Dreesen, Philippe; Tiels, Koen; Noël, Jean-Philippe; Schoukens, Johan

2018-05-01

Recent work on black-box polynomial nonlinear state-space modeling for hysteresis identification has provided promising results, but struggles with a large number of parameters due to the use of multivariate polynomials. This drawback is tackled in the current paper by applying a decoupling approach that results in a more parsimonious representation involving univariate polynomials. This work is carried out numerically on input-output data generated by a Bouc-Wen hysteretic model and follows up on earlier work of the authors. The current article discusses the polynomial decoupling approach and explores the selection of the number of univariate polynomials with the polynomial degree. We have found that the presented decoupling approach is able to reduce the number of parameters of the full nonlinear model up to about 50%, while maintaining a comparable output error level.

Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.

2008-01-01

In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of <2. The single frequency UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.

Cascading Failures as Continuous Phase-Space Transitions

DOE PAGES

Yang, Yang; Motter, Adilson E.

2017-12-14

In network systems, a local perturbation can amplify as it propagates, potentially leading to a large-scale cascading failure. We derive a continuous model to advance our understanding of cascading failures in power-grid networks. The model accounts for both the failure of transmission lines and the desynchronization of power generators and incorporates the transient dynamics between successive steps of the cascade. In this framework, we show that a cascade event is a phase-space transition from an equilibrium state with high energy to an equilibrium state with lower energy, which can be suitably described in a closed form using a global Hamiltonian-likemore » function. From this function, we show that a perturbed system cannot always reach the equilibrium state predicted by quasi-steady-state cascade models, which would correspond to a reduced number of failures, and may instead undergo a larger cascade. We also show that, in the presence of two or more perturbations, the outcome depends strongly on the order and timing of the individual perturbations. These results offer new insights into the current understanding of cascading dynamics, with potential implications for control interventions.« less

Cascading Failures as Continuous Phase-Space Transitions

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

Yang, Yang; Motter, Adilson E.

In network systems, a local perturbation can amplify as it propagates, potentially leading to a large-scale cascading failure. We derive a continuous model to advance our understanding of cascading failures in power-grid networks. The model accounts for both the failure of transmission lines and the desynchronization of power generators and incorporates the transient dynamics between successive steps of the cascade. In this framework, we show that a cascade event is a phase-space transition from an equilibrium state with high energy to an equilibrium state with lower energy, which can be suitably described in a closed form using a global Hamiltonian-likemore » function. From this function, we show that a perturbed system cannot always reach the equilibrium state predicted by quasi-steady-state cascade models, which would correspond to a reduced number of failures, and may instead undergo a larger cascade. We also show that, in the presence of two or more perturbations, the outcome depends strongly on the order and timing of the individual perturbations. These results offer new insights into the current understanding of cascading dynamics, with potential implications for control interventions.« less

Flight State Identification of a Self-Sensing Wing via an Improved Feature Selection Method and Machine Learning Approaches

PubMed Central

Chen, Xi; Wu, Qi; Ren, He; Chang, Fu-Kuo

2018-01-01

In this work, a data-driven approach for identifying the flight state of a self-sensing wing structure with an embedded multi-functional sensing network is proposed. The flight state is characterized by the structural vibration signals recorded from a series of wind tunnel experiments under varying angles of attack and airspeeds. A large feature pool is created by extracting potential features from the signals covering the time domain, the frequency domain as well as the information domain. Special emphasis is given to feature selection in which a novel filter method is developed based on the combination of a modified distance evaluation algorithm and a variance inflation factor. Machine learning algorithms are then employed to establish the mapping relationship from the feature space to the practical state space. Results from two case studies demonstrate the high identification accuracy and the effectiveness of the model complexity reduction via the proposed method, thus providing new perspectives of self-awareness towards the next generation of intelligent air vehicles. PMID:29710832

Space-time least-squares Petrov-Galerkin projection in nonlinear model reduction.

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

Choi, Youngsoo; Carlberg, Kevin Thomas

Our work proposes a space-time least-squares Petrov-Galerkin (ST-LSPG) projection method for model reduction of nonlinear dynamical systems. In contrast to typical nonlinear model-reduction methods that first apply Petrov-Galerkin projection in the spatial dimension and subsequently apply time integration to numerically resolve the resulting low-dimensional dynamical system, the proposed method applies projection in space and time simultaneously. To accomplish this, the method first introduces a low-dimensional space-time trial subspace, which can be obtained by computing tensor decompositions of state-snapshot data. The method then computes discrete-optimal approximations in this space-time trial subspace by minimizing the residual arising after time discretization over allmore » space and time in a weighted ℓ 2-norm. This norm can be de ned to enable complexity reduction (i.e., hyper-reduction) in time, which leads to space-time collocation and space-time GNAT variants of the ST-LSPG method. Advantages of the approach relative to typical spatial-projection-based nonlinear model reduction methods such as Galerkin projection and least-squares Petrov-Galerkin projection include: (1) a reduction of both the spatial and temporal dimensions of the dynamical system, (2) the removal of spurious temporal modes (e.g., unstable growth) from the state space, and (3) error bounds that exhibit slower growth in time. Numerical examples performed on model problems in fluid dynamics demonstrate the ability of the method to generate orders-of-magnitude computational savings relative to spatial-projection-based reduced-order models without sacrificing accuracy.« less

Wigner Function Reconstruction in Levitated Optomechanics

NASA Astrophysics Data System (ADS)

Rashid, Muddassar; Toroš, Marko; Ulbricht, Hendrik

2017-10-01

We demonstrate the reconstruction of theWigner function from marginal distributions of the motion of a single trapped particle using homodyne detection. We show that it is possible to generate quantum states of levitated optomechanical systems even under the efect of continuous measurement by the trapping laser light. We describe the opto-mechanical coupling for the case of the particle trapped by a free-space focused laser beam, explicitly for the case without an optical cavity. We use the scheme to reconstruct the Wigner function of experimental data in perfect agreement with the expected Gaussian distribution of a thermal state of motion. This opens a route for quantum state preparation in levitated optomechanics.

The International Space Station: Operations and Assembly - Learning From Experiences - Past, Present, and Future

NASA Technical Reports Server (NTRS)

Fuller, Sean; Dillon, William F.

2006-01-01

As the Space Shuttle continues flight, construction and assembly of the International Space Station (ISS) carries on as the United States and our International Partners resume the building, and continue to carry on the daily operations, of this impressive and historical Earth-orbiting research facility. In his January 14, 2004, speech announcing a new vision for America s space program, President Bush ratified the United States commitment to completing construction of the ISS by 2010. Since the launch and joining of the first two elements in 1998, the ISS and the partnership have experienced and overcome many challenges to assembly and operations, along with accomplishing many impressive achievements and historical firsts. These experiences and achievements over time have shaped our strategy, planning, and expectations. The continual operation and assembly of ISS leads to new knowledge about the design, development and operation of systems and hardware that will be utilized in the development of new deep-space vehicles needed to fulfill the Vision for Exploration and to generate the data and information that will enable our programs to return to the Moon and continue on to Mars. This paper will provide an overview of the complexity of the ISS Program, including a historical review of the major assembly events and operational milestones of the program, along with the upcoming assembly plans and scheduled missions of the space shuttle flights and ISS Assembly sequence.

A squeezed light source operated under high vacuum

PubMed Central

Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.

2015-01-01

Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments. PMID:26657616

Advanced space solar dynamic receivers

NASA Technical Reports Server (NTRS)

Strumpf, Hal J.; Coombs, Murray G.; Lacy, Dovie E.

1988-01-01

A study has been conducted to generate and evaluate advanced solar heat receiver concepts suitable for orbital application with Brayton and Stirling engine cycles in the 7-kW size range. The generated receiver designs have thermal storage capability (to enable power production during the substantial eclipse period which accompanies typical orbits) and are lighter and smaller than state-of-the-art systems, such as the Brayton solar receiver being designed and developed by AiResearch for the NASA Space Station. Two receiver concepts have been developed in detail: a packed bed receiver and a heat pipe receiver. The packed bed receiver is appropriate for a Brayton engine; the heat pipe receiver is applicable for either a Brayton or Stirling engine. The thermal storage for both concepts is provided by the melting and freezing of a salt. Both receiver concepts offer substantial improvements in size and weight compared to baseline receivers.

Detached Eddy Simulation Results for a Space Launch System Configuration at Liftoff Conditions and Comparison with Experiment

NASA Technical Reports Server (NTRS)

Krist, Steven E.; Ghaffari, Farhad

2015-01-01

Computational simulations for a Space Launch System configuration at liftoff conditions for incidence angles from 0 to 90 degrees were conducted in order to generate integrated force and moment data and longitudinal lineloads. While the integrated force and moment coefficients can be obtained from wind tunnel testing, computational analyses are indispensable in obtaining the extensive amount of surface information required to generate proper lineloads. However, beyond an incidence angle of about 15 degrees, the effects of massive flow separation on the leeward pressure field is not well captured with state of the art Reynolds Averaged Navier-Stokes methods, necessitating the employment of a Detached Eddy Simulation method. Results from these simulations are compared to the liftoff force and moment database and surface pressure data derived from a test in the NASA Langley 14- by 22-Foot Subsonic Wind Tunnel.

A squeezed light source operated under high vacuum

NASA Astrophysics Data System (ADS)

Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.

2015-12-01

Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments.

Bringing Solid-State Magnetocaloric Cooling to the Market: A Commercialization Plan

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

Abu-Heiba, Ahmad; Sikes, Karen; Blackburn, Julia

Air conditioning has become a staple in American life, bringing improved health, productivity, and comfort to 93% of single-family homes as of 2015, compared to only 76% in 1990. This rise in demand has contributed to the 2.51 quads (12.5%) of total annual energy consumption in residential buildings attributable to space cooling (U.S. Energy Information Administration 2017). Accompanying this upward trend in space cooling has been increased refrigerant use, which has historically contributed to ozone depletion, global warming, or both. The Oak Ridge National Laboratory – along with German-based partner Vacuumschmelze GmbH & Co. KG – is working to reducemore » energy consumption and refrigerant use through the development of a next-generation, solid-state magnetocaloric cooling system. The purpose of this study is to investigate market potential of these systems in the United States, including information on the industry landscape, market share and unit shipment projections, optimal price points, and barriers to market entry.« less

Flat electronic bands in fractal-kagomé network and the effect of perturbation

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

Nandy, Atanu, E-mail: atanunandy1989@gmail.com; Chakrabarti, Arunava, E-mail: arunava-chakrabarti@yahoo.co.in

2016-05-06

We demonstrate an analytical prescription of demonstrating the flat band [FB] states in a fractal incorporated kagomé type network that can give rise to a countable infinity of flat non-dispersive eigenstates with a multitude of localization area. The onset of localization can, in principle, be delayed in space by an appropriate choice of energy regime. The length scale, at which the onset of localization for each mode occurs, can be tuned at will following the formalism developed within the framework of real space renormalization group. This scheme leads to an exact determination of energy eigenvalue for which one can havemore » dispersionless flat electronic bands. Furthermore, we have shown the effect ofuniform magnetic field for the same non-translationally invariant network model that has ultimately led to an‘apparent invisibility’ of such staggered localized states and to generate absolutely continuous sub-bands in the energy spectrum and again an interesting re-entrant behavior of those FB states.« less

Catalogue Creation for Space Situational Awareness with Optical Sensors

NASA Astrophysics Data System (ADS)

Hobson, T.; Clarkson, I.; Bessell, T.; Rutten, M.; Gordon, N.; Moretti, N.; Morreale, B.

2016-09-01

In order to safeguard the continued use of space-based technologies, effective monitoring and tracking of man-made resident space objects (RSOs) is paramount. The diverse characteristics, behaviours and trajectories of RSOs make space surveillance a challenging application of the discipline that is tracking and surveillance. When surveillance systems are faced with non-canonical scenarios, it is common for human operators to intervene while researchers adapt and extend traditional tracking techniques in search of a solution. A complementary strategy for improving the robustness of space surveillance systems is to place greater emphasis on the anticipation of uncertainty. Namely, give the system the intelligence necessary to autonomously react to unforeseen events and to intelligently and appropriately act on tenuous information rather than discard it. In this paper we build from our 2015 campaign and describe the progression of a low-cost intelligent space surveillance system capable of autonomously cataloguing and maintaining track of RSOs. It currently exploits robotic electro-optical sensors, high-fidelity state-estimation and propagation as well as constrained initial orbit determination (IOD) to intelligently and adaptively manage its sensors in order to maintain an accurate catalogue of RSOs. In a step towards fully autonomous cataloguing, the system has been tasked with maintaining surveillance of a portion of the geosynchronous (GEO) belt. Using a combination of survey and track-refinement modes, the system is capable of maintaining a track of known RSOs and initiating tracks on previously unknown objects. Uniquely, due to the use of high-fidelity representations of a target's state uncertainty, as few as two images of previously unknown RSOs may be used to subsequently initiate autonomous search and reacquisition. To achieve this capability, particularly within the congested environment of the GEO-belt, we use a constrained admissible region (CAR) to generate a plausible estimate of the unknown RSO's state probability density function and disambiguate measurements using a particle-based joint probability data association (JPDA) method. Additionally, the use of alternative CAR generation methods, incorporating catalogue-based priors, is explored and tested. We also present the findings of two field trials of an experimental system that incorporates these techniques. The results demonstrate that such a system is capable of autonomously searching for an RSO that was briefly observed days prior in a GEO-survey and discriminating it from the measurements of other previously catalogued RSOs.

A Comparison of Forecast Error Generators for Modeling Wind and Load Uncertainty

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

Lu, Ning; Diao, Ruisheng; Hafen, Ryan P.

2013-12-18

This paper presents four algorithms to generate random forecast error time series, including a truncated-normal distribution model, a state-space based Markov model, a seasonal autoregressive moving average (ARMA) model, and a stochastic-optimization based model. The error time series are used to create real-time (RT), hour-ahead (HA), and day-ahead (DA) wind and load forecast time series that statistically match historically observed forecasting data sets, used for variable generation integration studies. A comparison is made using historical DA load forecast and actual load values to generate new sets of DA forecasts with similar stoical forecast error characteristics. This paper discusses and comparesmore » the capabilities of each algorithm to preserve the characteristics of the historical forecast data sets.« less

Four generations of sodium guide star lasers for adaptive optics in astronomy and space situational awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, Céline; Fetzer, Gregory J.

2016-07-01

This paper recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analyzing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980s and 1990s. These experimental systems were turned into the first laser guide star facilities to equip mediumto- large diameter adaptive optics telescopes, opening a new era of Laser Guide Star Adaptive Optics (LGS AO)-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000s that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8 to 10m-class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers are being or will soon be deployed at three astronomical telescopes and two space surveillance stations. These highly promising systems are still relatively large to install on telescopes and they remain significantly expensive to procure and maintain. We are thus proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide a definitive solution to the problem of sodium LGS AO laser sources for all astronomy and space situational awareness applications.

From Dye Laser Factory to Portable Semiconductor Laser: Four Generations of Sodium Guide Star Lasers for Adaptive Optics in Astronomy and Space Situational Awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, C.; Fetzer, G.

This presentation recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analysing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980's and 1990's. These experimental systems were turned into the first laser guide star facilities to equip medium-to-large diameter adaptive optics telescopes, opening a new era of LGS AO-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000's that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8-10m class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers will be deployed at two astronomical telescopes and at least one space debris tracking station this year. Although highly promising, these systems remain significantly expensive and they have yet to demonstrate high performance in the field. We are proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide the final solution to the problem of sodium laser guide star adaptive optics for all astronomy and space situational awareness applications.

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

Strauss, Y.; Horwitz, L. P.; Eisenberg, E.

We discuss the quantum Lax-Phillips theory of scattering and unstable systems. In this framework, the decay of an unstable system is described by a semigroup. The spectrum of the generator of the semigroup corresponds to the singularities of the Lax-Phillips S-matrix. In the case of discrete (complex) spectrum of the generator of the semigroup, associated with resonances, the decay law is exactly exponential. The states corresponding to these resonances (eigenfunctions of the generator of the semigroup) lie in the Lax-Phillips Hilbert space, and therefore all physical properties of the resonant states can be computed. We show that the Lax-Phillips S-matrixmore » is unitarily related to the S-matrix of standard scattering theory by a unitary transformation parametrized by the spectral variable σ of the Lax-Phillips theory. Analytic continuation in σ has some of the properties of a method developed some time ago for application to dilation analytic potentials. We work out an illustrative example using a Lee-Friedrichs model for the underlying dynamical system.« less

Medium generated gap in gravity and a 3D gauge theory

NASA Astrophysics Data System (ADS)

Gabadadze, Gregory; Older, Daniel

2018-05-01

It is well known that a physical medium that sets a Lorentz frame generates a Lorentz-breaking gap for a graviton. We examine such generated "mass" terms in the presence of a fluid medium whose ground state spontaneously breaks spatial translation invariance in d =D +1 spacetime dimensions, and for a solid in D =2 spatial dimensions. By requiring energy positivity and subluminal propagation, certain constraints are placed on the equation of state of the medium. In the case of D =2 spatial dimensions, classical gravity can be recast as a Chern-Simons gauge theory, and motivated by this we recast the massive theory of gravity in AdS3 as a massive Chern-Simons gauge theory with an unusual mass term. We find that in the flat space limit the Chern-Simons theory has a novel gauge invariance that mixes the kinetic and mass terms, and enables the massive theory with a noncompact internal group to be free of ghosts and tachyons.

Cabin Air Quality On Board Mir and the International Space Station: A Comparison

NASA Technical Reports Server (NTRS)

Macatangay, Ariel; Perry, Jay L.

2007-01-01

The maintenance of the cabin atmosphere aboard spacecraft is critical not only to its habitability but also to its function. Ideally, air quality can be maintained by striking a proper balance between the generation and removal of contaminants. Both very dynamic processes, the balance between generation and removal can be difficult to maintain and control because the state of the cabin atmosphere is in constant evolution responding to different perturbations. Typically, maintaining a clean cabin environment on board crewed spacecraft and space habitats is the central function of the environmental control and life support (ECLS) system. While active air quality control equipment is deployed on board every vehicle to remove carbon dioxide, water vapor, and trace chemical components from the cabin atmosphere, perturbations associated with logistics, vehicle construction and maintenance, and ECLS system configuration influence the resulting cabin atmospheric quality. The air-quality data obtained from the International Space Station (ISS) and NASA-Mir programs provides a wealth of information regarding the maintenance of the cabin atmosphere aboard long-lived space habitats. A comparison of the composition of the trace chemical contaminant load is presented. Correlations between ground-based and in-flight operations that influence cabin atmospheric quality are identified and discussed, and observations on cabin atmospheric quality during the NASA-Mir expeditions and the International Space Station are explored.

Close Approach Prediction Analysis of the Earth Science Constellation with the Fengyun-1C Debris

NASA Technical Reports Server (NTRS)

Duncan, Matthew; Rand, David K.

2008-01-01

Routine satellite operations for the Earth Science Constellation (ESC) include collision risk assessment between members of the constellation and other orbiting space objects. Each day, close approach predictions are generated by a U.S. Department of Defense Joint Space Operations Center Orbital Safety Analyst using the high accuracy Space Object Catalog maintained by the Air Force's 1" Space Control Squadron. Prediction results and other ancillary data such as state vector information are sent to NASAJGoddard Space Flight Center's (GSFC's) Collision Risk Assessment analysis team for review. Collision analysis is performed and the GSFC team works with the ESC member missions to develop risk reduction strategies as necessary. This paper presents various close approach statistics for the ESC. The ESC missions have been affected by debris from the recent anti-satellite test which destroyed the Chinese Fengyun- 1 C satellite. The paper also presents the percentage of close approach events induced by the Fengyun-1C debris, and presents analysis results which predict the future effects on the ESC caused by this event. Specifically, the Fengyun-1C debris is propagated for twenty years using high-performance computing technology and close approach predictions are generated for the ESC. The percent increase in the total number of conjunction events is considered to be an estimate of the collision risk due to the Fengyun-1C break- UP.

Commercialization and internationalization of the next-generation launch system

NASA Astrophysics Data System (ADS)

Bille, Matthew A.; Richie, George E.; Bille, Deborah A.

1996-03-01

The United States, ESA, Russia, and Japan are all pursuing the goal of a next-generation launch system. However, economic constraints may ground these programs, as they did hypersonic spaceplane efforts. In today's constrained fiscal environment, engineering is secondary unless the most practical economic and political approach is also found. While international efforts face national concerns over jobs and competitiveness, low-cost access to orbit will open up space to whole new industries. In the long run, all involved nations will gain economically if a next-generation launcher is built, and all will lose if individual efforts fail. An international consortium is most likely to amass the resources needed. The consortium would not be dedicated to any single technical concept, but would select from industry proposals to design and build the technology demonstrator. The goal is to get one working system built: after that, it is not critical whether we have one cooperative operational system or a dozen competing ones. What is critical is not to miss another chance to launch the era of space commercialization.

Dynamic wave field synthesis: enabling the generation of field distributions with a large space-bandwidth product.

PubMed

Kamau, Edwin N; Heine, Julian; Falldorf, Claas; Bergmann, Ralf B

2015-11-02

We present a novel approach for the design and fabrication of multiplexed computer generated volume holograms (CGVH) which allow for a dynamic synthesis of arbitrary wave field distributions. To achieve this goal, we developed a hybrid system that consists of a CGVH as a static element and an electronically addressed spatial light modulator as the dynamic element. We thereby derived a new model for describing the scattering process within the inhomogeneous dielectric material of the hologram. This model is based on the linearization of the scattering process within the Rytov approximation and incorporates physical constraints that account for voxel based laser-lithography using micro-fabrication of the holograms in a nonlinear optical material. In this article we demonstrate that this system basically facilitates a high angular Bragg selectivity on the order of 1°. Additionally, it allows for a qualitatively low cross-talk dynamic synthesis of predefined wave fields with a much larger space-bandwidth product (SBWP ≥ 8.7 × 10(6)) as compared to the current state of the art in computer generated holography.

X-Ray Emission from the Terrestrial Magnetosheath

NASA Astrophysics Data System (ADS)

Robertson, I. P.; Collier, M. R.; Cravens, T. E.; Fok, M.

2004-12-01

X-rays are generated throughout the terrestrial magnetosheath as a consequence of charge transfer collisions between heavy solar wind ions and geocoronal neutrals. The solar wind ions resulting from these collisions are left in highly excited states and emit extreme ultraviolet or soft X-ray photons. A model has been created to simulate this X-ray radiation. Previously simulated images were created as seen from an observation point outside the geocorona. The locations of the bow shock and magnetopause were evident in these images. The cusps, however, were not taken into account in the model. We have now used dynamic three-dimensional simulations of the solar wind, magnetosheath and magnetosphere that were performed by the CCMC at Goddard Space Flight Center for the March 31st , 2001 geomagnetic storm. We have generated a sky map of the expected X-Ray emissions as would have been seen by an observer at the IMAGE space craft location at that time. We have also generated images as seen from an observation point well outside the geocorona. In both cases the presence of the cusps can clearly be observed.

Bridging the Worlds of Entertainment and Space - One Element of the Space Generation Foundation

NASA Astrophysics Data System (ADS)

Hildago, L.

2002-01-01

Programme on Space Applications, SGSabstracts@unsgac.org/fax +1(281)244-7478 The Space Generation Foundation, founder of ISU, is the current home for Space Rocks!, Yuri's Night, and other space projects focused on education, outreach, and sustainable development worldwide. One particular area of success in 2001/2002 has been the involvement of the entertainment community in space events. Yuri's Night brought together musicians, DJs, artists, and the public to celebrate space. Space Rocks will do the same on a much larger scale, employing film, theatre, poetry, music, art, advertising firms, and other unconventional media to communicate space to the public. We will present about the aims and future plans of the Foundation. The Space Generation Advisory Council in support of the United Nations Programme on Space Applications has as its main focus Space education and outreach. Since the Space Generation Forum in 1999, successful global education and outreach projects have been implemented by young people around the world. These and new ideas are being further developed at the Space Generation Summit (SGS), an event at World Space Congress (WSC) that will unite international students and young professionals to develop a youth vision and strategy for the peaceful uses of space. SGS, endorsed by the United Nations, will take place from October 11-13th, during which the 200 delegates will discuss ongoing youth space activities, particularly those stemming from the UNISPACE- III/SGF and taken forward by the Space Generation Advisory Council. Delegates will address a variety of topics with the goal of devising new recommendations according to the theme, 'Accelerating Our Pace in Space'. The material presented here and in other technical sessions throughout WSC includes the results of these discussions.

Experimental Evaluation of Optically Polished Aluminum Panels on the Deep Space Network's 34 Meter Antenna

NASA Technical Reports Server (NTRS)

Vilnrotter, V.

2011-01-01

The potential development of large aperture ground?based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation is to polish the aluminum reflector panels of 34?meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by state of?the?art polished aluminum panels. Theoretical analyses of receiving antenna pointing, temporal synchronization and data detection have been addressed in previous papers. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. Two polished aluminum panels (a standard DSN panel polished to high reflectance, and a custom designed aluminum panel with much better surface quality) have been mounted on the 34 meter research antenna at Deep?Space Station 13 (DSS?13), and a remotely controlled CCD camera with a large CCD sensor in a weather?proof container has been installed next to the subreflector, pointed directly at the custom polished panel. The point?spread function (PSF) generated by the Vertex polished panel has been determined to be smaller than the sensor of the CCD camera, hence a detailed picture of the PSF can be obtained every few seconds, and the sensor array data processed to determine the center of the intensity distribution. In addition to estimating the center coordinates, expected communications performance can also been evaluated with the recorded data. The results of preliminary pointing experiments with the Vertex polished panel receiver using the planet Jupiter to simulate the PSF generated by a deep?space optical transmitter are presented and discussed in this paper.

Space Radiation Monitoring Center at SINP MSU

NASA Astrophysics Data System (ADS)

Kalegaev, Vladimir; Barinova, Wera; Barinov, Oleg; Bobrovnikov, Sergey; Dolenko, Sergey; Mukhametdinova, Ludmila; Myagkova, Irina; Nguen, Minh; Panasyuk, Mikhail; Shiroky, Vladimir; Shugay, Julia

2015-04-01

Data on energetic particle fluxes from Russian satellites have been collected in Space monitoring data center at Moscow State University in the near real-time mode. Web-portal http://smdc.sinp.msu.ru/ provides operational information on radiation state of the near-Earth space. Operational data are coming from space missions ELECTRO-L1, Meteor-M2. High-resolution data on energetic electron fluxes from MSU's satellite VERNOV with RELEC instrumentation on board are also available. Specific tools allow the visual representation of the satellite orbit in 3D space simultaneously with particle fluxes variations. Concurrent operational data coming from other spacecraft (ACE, GOES, SDO) and from the Earth's surface (geomagnetic indices) are used to represent geomagnetic and radiation state of near-Earth environment. Internet portal http://swx.sinp.msu.ru provides access to the actual data characterizing the level of solar activity, geomagnetic and radiation conditions in heliosphere and the Earth's magnetosphere in the real-time mode. Operational forecasting services automatically generate alerts on particle fluxes enhancements above the threshold values, both for SEP and relativistic electrons, using data from LEO and GEO orbits. The models of space environment working in autonomous mode are used to generalize the information obtained from different missions for the whole magnetosphere. On-line applications created on the base of these models provide short-term forecasting for SEP particles and relativistic electron fluxes at GEO and LEO, Dst and Kp indices online forecasting up to 1.5 hours ahead. Velocities of high-speed streams in solar wind on the Earth orbit are estimated with advance time of 3-4 days. Visualization system provides representation of experimental and modeling data in 2D and 3D.

Data for giant constrictors - Biological management profiles and an establishment risk assessment for nine large species of pythons, anacondas, and the boa constrictor

USGS Publications Warehouse

Jarnevich, C.S.; Rodda, G.H.; Reed, R.N.

2011-01-01

Giant Constrictors' Climate Space The giant constrictors' climate space data set represents the information needed to recreate the climate space and climate matching analyses in Reed and Rodda (2009). A detailed methodology and results are included in that report. The data include locations for nine species of large constrictors including Python molurus, Broghammerus reticulatus, P. sebae, P. natalensis, Boa constrictor, Eunectes notaeus, E. deschauenseei, E. beniensis, and E. murinus. The locations are from published sources. Climate data are included for monthly precipitation and average monthly temperature along with the species locations. The individual spreadsheets of location data match the figures in the Reed and Rodda (2009) report, illustrating areas of the mainland United States that match the climate envelope of the native range. The precipitation and temperature data at each location were used to determine the climate space for each species. Graphs of climate space formed the basis for the algorithms in the data set, and more details can be found in Reed and Rodda (2009). These algorithms were used in ArcGIS to generate maps of areas in the United States that matched the climate space of locations of the snakes in their native range. We discovered a rounding error in ArcGIS in the implementation of the algorithms, which has been corrected here. Therefore the shapefiles are slightly different than those appearing in the risk assessment figures illustrating areas of the United States that match the climate envelope of the species in their native ranges. However, the suitable localities are not different at the scale of intended use for these maps, although there are more noticeable differences between areas classified as 'too cold' and 'too hot'.

NASA Alternate Access to Station Service Concept

NASA Technical Reports Server (NTRS)

Bailey, Michelle D.; Crumbly, Chris

2001-01-01

The evolving nature of the NASA space enterprise compels the agency to develop new and innovative space systems concepts. NASA, working with increasingly strained budgets and a declining manpower base, is attempting to transform from operational activities to procurement of commercial services. NASA's current generation reusable launch vehicle, the Shuttle, is in transition from a government owned and operated entity to a commercial venture to reduce the civil servant necessities for that program. NASA foresees its second generation launch vehicles being designed and operated by industry for commercial and government services. The "service" concept is a pioneering effort by NASA. The purpose the "service" is not only to reduce the civil servant overhead but will free up government resources for further research - and enable industry to develop a space business case so that industry can sustain itself beyond government programs. In addition, NASA desires a decreased responsibility thereby decreasing liability. The Second Generation Reusable Launch Vehicle (RLV) program is implementing NASA's Space Launch Initiative (SLI) to enable industry to develop the launch vehicles of the future. The Alternate Access to Station (AAS) project office within this program is chartered with enabling industry to demonstrate an alternate access capability for the International Space Station (ISS). The project will not accomplish this by traditional government procurement methods, not by integrating the space system within the project office, or by providing the only source of business for the new capability. The project funds will ultimately be used to purchase a service to take re-supply cargo to the ISS, much the same as any business might purchase a service from FedEx to deliver a package to its customer. In the near term, the project will fund risk mitigation efforts for enabling technologies. AAS is in some ways a precursor to the 2nd Generation RLV. By accomplishing ISS resupply with existing technologies, not only will a new category of autonomous vehicles deliver cargo, but a commercial business base will be incubated that will improve the likelihood of commercial convergence with the next generation of RLVs. Traditional paradigms in government management and acquisition philosophy are being challenged in order to bring about the objective of the AAS project. The phased procurement approach is proving to be the most questionable aspect to date. This work addresses the fresh approach AAS is adopting in management and procurement through a study of the AAS history, current solutions, key technologies, procurement complications, and an incremental forward plan leading to the purchase of a service to deliver goods to ISS. Included in this work is a discussion of the Commercial Space Act of 1998 and how it affects government purchase of space launch and space vehicle services. Industry should find these topics pertinent to their current state of business.

NASA Alternate Access to Station Service Concept

NASA Astrophysics Data System (ADS)

Bailey, M. D.; Crumbly, C.

2002-01-01

The evolving nature of the NASA space enterprise compels the agency to develop new and innovative space systems concepts. NASA, working with increasingly strained budgets and a declining manpower base, is attempting to transform from operational activities to procurement of commercial services. NASA's current generation reusable launch vehicle, the Shuttle, is in transition from a government owned and operated entity to a commercial venture to reduce the civil servant necessities for that program. NASA foresees its second generation launch vehicles being designed and operated by industry for commercial and government services. The "service" concept is a pioneering effort by NASA. The purpose the "service" is not only to reduce the civil servant overhead but will free up government resources for further research and enable industry to develop a space business case so that industry can sustain itself beyond government programs. In addition, NASA desires a decreased responsibility thereby decreasing liability. The Second Generation Reusable Launch Vehicle (RLV) program is implementing NASA's Space Launch Initiative (SLI) to enable industry to develop the launch vehicles of the future. The Alternate Access to Station (AAS) project office within this program is chartered with enabling industry to demonstrate an alternate access capability for the International Space Station (ISS). The project will not accomplish this by traditional government procurement methods, not by integrating the space system within the project office, or by providing the only source of business for the new capability. The project funds will ultimately be used to purchase a service to take re-supply cargo to the ISS, much the same as any business might purchase a service from FedEx to deliver a package to its customer. In the near term, the project will fund risk mitigation efforts for enabling technologies. AAS is in some ways a precursor to the 2nd Generation RLV. By accomplishing ISS resupply with existing technologies, not only will a new category of autonomous vehicles deliver cargo, but a commercial business base will be incubated that will improve the likelihood of commercial convergence with the next generation of RLVs. Traditional paradigms in government management and acquisition philosophy are being challenged in order to bring about the objective of the AAS project. The phased procurement approach is proving to be the most questionable aspect to date. This work addresses the fresh approach AAS is adopting in management and procurement through a study of the AAS history, current solutions, key technologies, procurement complications, and an incremental forward plan leading to the purchase of a service to deliver goods to ISS. Included in this work is a discussion of the Commercial Space Act of 1998 and how it affects government purchase of space launch and space vehicle services. Industry should find these topics pertinent to their current state of business.

Estimation Filter for Alignment of the Spitzer Space Telescope

NASA Technical Reports Server (NTRS)

Bayard, David

2007-01-01

A document presents a summary of an onboard estimation algorithm now being used to calibrate the alignment of the Spitzer Space Telescope (formerly known as the Space Infrared Telescope Facility). The algorithm, denoted the S2P calibration filter, recursively generates estimates of the alignment angles between a telescope reference frame and a star-tracker reference frame. At several discrete times during the day, the filter accepts, as input, attitude estimates from the star tracker and observations taken by the Pointing Control Reference Sensor (a sensor in the field of view of the telescope). The output of the filter is a calibrated quaternion that represents the best current mean-square estimate of the alignment angles between the telescope and the star tracker. The S2P calibration filter incorporates a Kalman filter that tracks six states - two for each of three orthogonal coordinate axes. Although, in principle, one state per axis is sufficient, the use of two states per axis makes it possible to model both short- and long-term behaviors. Specifically, the filter properly models transient learning, characteristic times and bounds of thermomechanical drift, and long-term steady-state statistics, whether calibration measurements are taken frequently or infrequently. These properties ensure that the S2P filter performance is optimal over a broad range of flight conditions, and can be confidently run autonomously over several years of in-flight operation without human intervention.

Systematic Expansion of Active Spaces beyond the CASSCF Limit: A GASSCF/SplitGAS Benchmark Study.

PubMed

Vogiatzis, Konstantinos D; Li Manni, Giovanni; Stoneburner, Samuel J; Ma, Dongxia; Gagliardi, Laura

2015-07-14

The applicability and accuracy of the generalized active space self-consistent field, (GASSCF), and (SplitGAS) methods are presented. The GASSCF method enables the exploration of larger active spaces than with the conventional complete active space SCF, (CASSCF), by fragmentation of a large space into subspaces and by controlling the interspace excitations. In the SplitGAS method, the GAS configuration interaction, CI, expansion is further partitioned in two parts: the principal, which includes the most important configuration state functions, and an extended, containing less relevant but not negligible ones. An effective Hamiltonian is then generated, with the extended part acting as a perturbation to the principal space. Excitation energies of ozone, furan, pyrrole, nickel dioxide, and copper tetrachloride dianion are reported. Various partitioning schemes of the GASSCF and SplitGAS CI expansions are considered and compared with the complete active space followed by second-order perturbation theory, (CASPT2), and multireference CI method, (MRCI), or available experimental data. General guidelines for the optimum applicability of these methods are discussed together with their current limitations.

Refusing Curriculum as a Space of Death for Black Female Subjects: A Black Feminist Reparative Reading of Jamaica Kincaid's "Girl"

ERIC Educational Resources Information Center

Ohito, Esther Oganda

2016-01-01

The currents of elitism surging through curriculum studies in the United States have long been of chief concern to critical scholars in the field. Elements of this elitism running along racialized, gendered, classed and other such lines elide to marginalize knowledge generated by and about the "other." For this racialized, gendered,…

Aeroelastic modeling of the active flexible wing wind-tunnel model

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Heeg, Jennifer; Bennett, Robert M.

1991-01-01

The primary issues involved in the generation of linear, state-space equations of motion of a flexible wind tunnel model, the Active Flexible Wing (AFW), are discussed. The codes that were used and their inherent assumptions and limitations are also briefly discussed. The application of the CAP-TSD code to the AFW for determination of the model's transonic flutter boundary is included as well.

Preparing the Next Generation of Earth Scientists: An Examination of Federal Education and Training Programs

ERIC Educational Resources Information Center

National Academies Press, 2013

2013-01-01

Earth science, which in this context does not include oceanic, atmospheric, and space sciences, is vital to the wellbeing of the United States and many of its issues, such as water resources, are expected to grow in importance. An earth science workforce will be needed to deal with this issues and it's important that this workforce draw on the…

Role of surface crossings in the photochemistry of nitromethane

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

Arenas, Juan F.; Otero, Juan C.; Pelaez, Daniel

2005-02-22

The photodissociation dynamics of nitromethane (CH{sub 3}NO{sub 2}) starting at the S{sub 3} excited state has been studied at the complete active space self-consistent field level of theory in conjunction with atomic natural orbital type basis sets. In addition, the energies of all the critical points and the energy profiles connecting them have been recomputed with the multiconfigurational second-order perturbation method. It is found that the key step in the reaction mechanism is a radiationless decay through an S{sub 3}/S{sub 2} conical intersection. The branching space spanned by the gradient difference and nonadiabatic coupling vectors of this crossing point comprisesmore » dissociation into excited nitromethane plus singlet atomic oxygen [CH{sub 3}NO(1A{sup ''})+O({sup 1}D)] and S{sub 3}{yields}S{sub 2} deactivation, respectively. Furthermore, deactivated nitromethane S{sub n(nlt3)} can decompose in subsequent steps into CH{sub 3}+NO{sub 2}, where NO{sub 2} is generated at least in two different electronic states (1 {sup 2}B{sub 2} and 1 {sup 2}A{sub 1}). It is shown that formation of excited nitric oxide NO(A {sup 2}{sigma}) arises from CH{sub 3}NO(1A{sup ''}) generated in the previous step. In addition, four crossings between singlet and triplet states are localized; however, no evidence is found for a relevant role of such crossings in the photochemistry of CH{sub 3}NO{sub 2} initiated at S{sub 3} state in the gas phase.« less

Correlations in state space can cause sub-optimal adaptation of optimal feedback control models.

PubMed

Aprasoff, Jonathan; Donchin, Opher

2012-04-01

Control of our movements is apparently facilitated by an adaptive internal model in the cerebellum. It was long thought that this internal model implemented an adaptive inverse model and generated motor commands, but recently many reject that idea in favor of a forward model hypothesis. In theory, the forward model predicts upcoming state during reaching movements so the motor cortex can generate appropriate motor commands. Recent computational models of this process rely on the optimal feedback control (OFC) framework of control theory. OFC is a powerful tool for describing motor control, it does not describe adaptation. Some assume that adaptation of the forward model alone could explain motor adaptation, but this is widely understood to be overly simplistic. However, an adaptive optimal controller is difficult to implement. A reasonable alternative is to allow forward model adaptation to 're-tune' the controller. Our simulations show that, as expected, forward model adaptation alone does not produce optimal trajectories during reaching movements perturbed by force fields. However, they also show that re-optimizing the controller from the forward model can be sub-optimal. This is because, in a system with state correlations or redundancies, accurate prediction requires different information than optimal control. We find that adding noise to the movements that matches noise found in human data is enough to overcome this problem. However, since the state space for control of real movements is far more complex than in our simple simulations, the effects of correlations on re-adaptation of the controller from the forward model cannot be overlooked.

Spintronics device made of topological materials

NASA Astrophysics Data System (ADS)

Wu, Jiansheng; Shi, Zhangsheng; Wang, Maoji

Topological Materials is a new state of matter of which the bulk states are gapped insulator or superconductor while the surface states are gapless metallic states. Such surface states are robust against local disorder and impurities due to its nontrivial topology. It induces unusual transport properties and shows nontrivial topological spin texture in real space. We have made use of these two exotic properties to make application in spintronics. For example, we propose to make spin-filter transistor using of 1D or 2D quantum anomalous Hall insulator or 2D topological Weyl semimetal, we also propose a device to measure the spin-polarization of current, a device to generate entangled entangled electron pairs. Startup funds of SUSTC, Shenzhen Peacock Plan, Shenzhen Free Exploration Plan with Grant Number JCYJ20150630145302225.

Modified Einstein and Navier-Stokes Equations

NASA Astrophysics Data System (ADS)

Bulyzhenkov, I. É.

2018-05-01

The appearance of inertial rest mass-energy is associated with the kinematic slowing-down of time and with the vortex state of the elementary massive space with zero integral of its kinetic and potential energies. An analog of the Einstein equation is found for moving densities of a non-empty metric space in the concept of the Einstein-Infeld material field. The vector consequences of this tensor equation for a metric medium of overlapping elementary carriers of continuous mass-energies allow us to modify the Navier-Stokes equation under inertial motion of the matter of the nonlocal field in the nonrelativistic limit. The nonlocality of massenergy generates kinematic accelerations of feedback to Newtonian acceleration, which impedes asymptotic divergence of energy fluxes. Stabilization of inertial media by dynamic Bernoulli pressure corresponds to nonlocal self-organization of Einstein-Infeld non-empty space and invalidates Newtonian localization of masses in empty space.

Deriving Tools from Real-Time Runs: A New CCMC Support for SEC and AFWA

NASA Technical Reports Server (NTRS)

Hesse, Michael; Rastatter, Lutz; MacNeice, Peter; Kuznetsova, Masha

2007-01-01

The Community Coordinated Modeling Center (CCMC) is a US inter-agency activity aiming at research in support of the generation of advanced space weather models. As one of its main functions, the CCMC provides to researchers the use of space science models, even if they are not model owners themselves. In particular, the CCMC provides to the research community the execution of "runs-on-request" for specific events of interest to space science researchers. Through this activity and the concurrent development of advanced visualization tools, CCMC provides, to the general science community, unprecedented access to a large number of state-of-the-art research models. CCMC houses models that cover the entire domain from the Sun to the Earth. In this presentation, we will provide an overview of CCMC modeling services that are available to support activities at the Space Environment Center, or at the Air Force Weather Agency.

The Next Generation of Space Cells for Diverse Environments

NASA Technical Reports Server (NTRS)

Bailey, Sheila; Landis, Geoffrey; Raffaelle, Ryne

2002-01-01

Future science, military and commercial space missions are incredibly diverse. Military and commercial missions range from large arrays of hundreds of kilowatt to small arrays of ten watts in various Earth orbits. While science missions also have small to very large power needs there are additional unique requirements to provide power for near-sun missions and planetary exploration including orbiters, landers and rovers both to the inner planets and the outer planets with a major emphasis in the near term on Mars. These mission requirements demand cells for low intensity, low temperature applications, high intensity, high temperature applications, dusty environments and often high radiation environments. This paper discusses mission requirements, the current state of the art of space solar cells, and a variety of both evolving thin-film cells as well as new technologies that may impact the future choice of space solar cells for a specific mission application.

Modified Einstein and Navier–Stokes Equations

NASA Astrophysics Data System (ADS)

Bulyzhenkov, I. É.

2018-05-01

The appearance of inertial rest mass-energy is associated with the kinematic slowing-down of time and with the vortex state of the elementary massive space with zero integral of its kinetic and potential energies. An analog of the Einstein equation is found for moving densities of a non-empty metric space in the concept of the Einstein-Infeld material field. The vector consequences of this tensor equation for a metric medium of overlapping elementary carriers of continuous mass-energies allow us to modify the Navier-Stokes equation under inertial motion of the matter of the nonlocal field in the nonrelativistic limit. The nonlocality of massenergy generates kinematic accelerations of feedback to Newtonian acceleration, which impedes asymptotic divergence of energy fluxes. Stabilization of inertial media by dynamic Bernoulli pressure corresponds to nonlocal self-organization of Einstein-Infeld non-empty space and invalidates Newtonian localization of masses in empty space.

Cooperative scattering and radiation pressure force in dense atomic clouds

NASA Astrophysics Data System (ADS)

Bachelard, R.; Piovella, N.; Courteille, Ph. W.

2011-07-01

Atomic clouds prepared in “timed Dicke” states, i.e. states where the phase of the oscillating atomic dipole moments linearly varies along one direction of space, are efficient sources of superradiant light emission [Scully , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.96.010501 96, 010501 (2006)]. Here, we show that, in contrast to previous assertions, timed Dicke states are not the states automatically generated by incident laser light. In reality, the atoms act back on the driving field because of the finite refraction of the cloud. This leads to nonuniform phase shifts, which, at higher optical densities, dramatically alter the cooperative scattering properties, as we show by explicit calculation of macroscopic observables, such as the radiation pressure force.

A Josephson radiation comb generator.

PubMed

Solinas, P; Gasparinetti, S; Golubev, D; Giazotto, F

2015-07-20

We propose the implementation of a Josephson Radiation Comb Generator (JRCG) based on a dc superconducting quantum interference device (SQUID) driven by an external magnetic field. When the magnetic flux crosses a diffraction node of the critical current interference pattern, the superconducting phase undergoes a jump of π and a voltage pulse is generated at the extremes of the SQUID. Under periodic drive this allows one to generate a sequence of sharp, evenly spaced voltage pulses. In the frequency domain, this corresponds to a comb-like structure similar to the one exploited in optics and metrology. With this device it is possible to generate up to several hundreds of harmonics of the driving frequency. For example, a chain of 50 identical high-critical-temperature SQUIDs driven at 1 GHz can deliver up to a 0.5 nW at 200 GHz. The availability of a fully solid-state radiation comb generator such as the JRCG, easily integrable on chip, may pave the way to a number of technological applications, from metrology to sub-millimeter wave generation.

Dark State Optical Lattice with a Subwavelength Spatial Structure

NASA Astrophysics Data System (ADS)

Wang, Y.; Subhankar, S.; Bienias, P.; ŁÄ cki, M.; Tsui, T.-C.; Baranov, M. A.; Gorshkov, A. V.; Zoller, P.; Porto, J. V.; Rolston, S. L.

2018-02-01

We report on the experimental realization of a conservative optical lattice for cold atoms with a subwavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a one-dimensional array of ultranarrow barriers with widths less than 10 nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice and find good agreement with theoretical predictions. Even on resonance, the observed lifetimes of atoms trapped in the lattice are as long as 44 ms, nearly 1 05 times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimensions and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with subwavelength spacings.

Computer image generation: Reconfigurability as a strategy in high fidelity space applications

NASA Technical Reports Server (NTRS)

Bartholomew, Michael J.

1989-01-01

The demand for realistic, high fidelity, computer image generation systems to support space simulation is well established. However, as the number and diversity of space applications increase, the complexity and cost of computer image generation systems also increase. One strategy used to harmonize cost with varied requirements is establishment of a reconfigurable image generation system that can be adapted rapidly and easily to meet new and changing requirements. The reconfigurability strategy through the life cycle of system conception, specification, design, implementation, operation, and support for high fidelity computer image generation systems are discussed. The discussion is limited to those issues directly associated with reconfigurability and adaptability of a specialized scene generation system in a multi-faceted space applications environment. Examples and insights gained through the recent development and installation of the Improved Multi-function Scene Generation System at Johnson Space Center, Systems Engineering Simulator are reviewed and compared with current simulator industry practices. The results are clear; the strategy of reconfigurability applied to space simulation requirements provides a viable path to supporting diverse applications with an adaptable computer image generation system.

Duality constructions from quantum state manifolds

NASA Astrophysics Data System (ADS)

Kriel, J. N.; van Zyl, H. J. R.; Scholtz, F. G.

2015-11-01

The formalism of quantum state space geometry on manifolds of generalised coherent states is proposed as a natural setting for the construction of geometric dual descriptions of non-relativistic quantum systems. These state manifolds are equipped with natural Riemannian and symplectic structures derived from the Hilbert space inner product. This approach allows for the systematic construction of geometries which reflect the dynamical symmetries of the quantum system under consideration. We analyse here in detail the two dimensional case and demonstrate how existing results in the AdS 2 /CF T 1 context can be understood within this framework. We show how the radial/bulk coordinate emerges as an energy scale associated with a regularisation procedure and find that, under quite general conditions, these state manifolds are asymptotically anti-de Sitter solutions of a class of classical dilaton gravity models. For the model of conformal quantum mechanics proposed by de Alfaro et al. [1] the corresponding state manifold is seen to be exactly AdS 2 with a scalar curvature determined by the representation of the symmetry algebra. It is also shown that the dilaton field itself is given by the quantum mechanical expectation values of the dynamical symmetry generators and as a result exhibits dynamics equivalent to that of a conformal mechanical system.

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

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

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

1986 Annual Conference on Nuclear and Space Radiation Effects, 23rd, Providence, RI, July 21-23, 1986, Proceedings

NASA Technical Reports Server (NTRS)

Ellis, Thomas D. (Editor)

1986-01-01

The present conference on the effects of nuclear and space radiation on electronic hardware gives attention to topics in the basic mechanisms of radiation effects, dosimetry and energy-dependent effects, electronic device radiation hardness assurance, SOI/SOS radiation effects, spacecraft charging and space radiation, IC radiation effects and hardening, single-event upset (SEU) phenomena and hardening, and EMP/SGEMP/IEMP phenomena. Specific treatments encompass the generation of interface states by ionizing radiation in very thin MOS oxides, the microdosimetry of meson energy deposited on 1-micron sites in Si, total dose radiation and engineering studies, plasma interactions with biased concentrator solar cells, the transient imprint memory effect in MOS memories, mechanisms leading to SEU, and the vaporization and breakdown of thin columns of water.

Modular Hamiltonians for deformed half-spaces and the averaged null energy condition

DOE PAGES

Faulkner, Thomas; Leigh, Robert G.; Parrikar, Onkar; ...

2016-09-08

We study modular Hamiltonians corresponding to the vacuum state for deformed half-spaces in relativistic quantum field theories on R 1,d-1. We show that in addition to the usual boost generator, there is a contribution to the modular Hamiltonian at first order in the shape deformation, proportional to the integral of the null components of the stress tensor along the Rindler horizon. We use this fact along with monotonicity of relative entropy to prove the averaged null energy condition in Minkowski space-time. This subsequently gives a new proof of the Hofman-Maldacena bounds on the parameters appearing in CFT three-point functions. Ourmore » main technical advance involves adapting newly developed perturbative methods for calculating entanglement entropy to the problem at hand. Our methods were recently used to prove certain results on the shape dependence of entanglement in CFTs and here we generalize these results to excited states and real time dynamics. Finally, we discuss the AdS/CFT counterpart of this result, making connection with the recently proposed gravitational dual for modular Hamiltonians in holographic theories.« less

Modular Hamiltonians for deformed half-spaces and the averaged null energy condition

NASA Astrophysics Data System (ADS)

Faulkner, Thomas; Leigh, Robert G.; Parrikar, Onkar; Wang, Huajia

2016-09-01

We study modular Hamiltonians corresponding to the vacuum state for deformed half-spaces in relativistic quantum field theories on {{R}}^{1,d-1} . We show that in addition to the usual boost generator, there is a contribution to the modular Hamiltonian at first order in the shape deformation, proportional to the integral of the null components of the stress tensor along the Rindler horizon. We use this fact along with monotonicity of relative entropy to prove the averaged null energy condition in Minkowski space-time. This subsequently gives a new proof of the Hofman-Maldacena bounds on the parameters appearing in CFT three-point functions. Our main technical advance involves adapting newly developed perturbative methods for calculating entanglement entropy to the problem at hand. These methods were recently used to prove certain results on the shape dependence of entanglement in CFTs and here we generalize these results to excited states and real time dynamics. We also discuss the AdS/CFT counterpart of this result, making connection with the recently proposed gravitational dual for modular Hamiltonians in holographic theories.

Recipe for generating Weyl semimetals with extended topologically protected features

NASA Astrophysics Data System (ADS)

Wang, R.; Zhao, J. Z.; Jin, Y. J.; Xu, W. P.; Gan, L.-Y.; Wu, X. Z.; Xu, H.; Tong, S. Y.

2017-09-01

We present a recipe that leads to Weyl semimetals with extended topologically protected features. We show that compounds in a family that possess time-reversal symmetry and share a noncentrosymmetric cubic structure with the space group F -43 m (no. 216) host robust Weyl fermions with extended and easily measurable protected features. The candidates in this family are compounds with different chemical formulas, A B2 , ABC, AB C2 , and ABCD, and their Fermi levels are predominantly populated by nontrivial Weyl fermions. Symmetry of the system requires that the Weyl nodes with opposite chirality are well separated in momentum space. Adjacent Weyl points have the same chirality; thus these Weyl nodes would not annihilate each other with respect to lattice perturbations. As Fermi arcs and surface states connect Weyl nodes with opposite chirality, the large separation of the latter in momentum space guarantees the appearance of very long arcs and surface states. This work demonstrates that the use of system symmetry by first-principles calculations is a powerful approach for discovering new Weyl semimetals with attractive features whose protected fermions may be candidates of many applications.

Modular Hamiltonians for deformed half-spaces and the averaged null energy condition

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

Faulkner, Thomas; Leigh, Robert G.; Parrikar, Onkar

We study modular Hamiltonians corresponding to the vacuum state for deformed half-spaces in relativistic quantum field theories on R 1,d-1. We show that in addition to the usual boost generator, there is a contribution to the modular Hamiltonian at first order in the shape deformation, proportional to the integral of the null components of the stress tensor along the Rindler horizon. We use this fact along with monotonicity of relative entropy to prove the averaged null energy condition in Minkowski space-time. This subsequently gives a new proof of the Hofman-Maldacena bounds on the parameters appearing in CFT three-point functions. Ourmore » main technical advance involves adapting newly developed perturbative methods for calculating entanglement entropy to the problem at hand. Our methods were recently used to prove certain results on the shape dependence of entanglement in CFTs and here we generalize these results to excited states and real time dynamics. Finally, we discuss the AdS/CFT counterpart of this result, making connection with the recently proposed gravitational dual for modular Hamiltonians in holographic theories.« less

Theater of Memory against a Background of Stars: A Generation Starship Concept between Fiction and Reality

NASA Astrophysics Data System (ADS)

Caroti, Simone

2009-03-01

The concept of the generation starship constitutes a feasible response to the serious travel-time restrictions that the light-speed limit imposes upon human exploration of deep space-``feasible'' in the sense that it could be realized within a reasonably short time span, given our present state of technological advancement. It was Tsiolkovsky, the Russian pioneer of space flight, who first conceptualized the generation starship. In his 1928 paper, The Future of Earth and Mankind, Tsiolkovsky imagines the creation of a fleet of ``Noah's Arks,'' self-sufficient, man-made worldlets that would travel to a distant star system over a period of hundreds or thousands of years, while the crew onboard simply live out their lives maintaining and piloting the ships, and have children whom they teach the necessary skills to do the same once they are gone. Their distant descendants, tens or hundreds of generations in the future, will complete the voyage when the ships finally arrive at their appointed destination. Since Tsiolkovsky's time, science and science fiction have leapfrogged each other in an attempt to imagine what the conditions and consequences of such a venture could be. For example: how could one maintain a stable society throughout such a long period of time-and what sort of governing body should operate during the voyage? How would the composition and number of the crew influence the danger of genetic drift or decay? How might the ship-born generations retain their commitment to the goals of the culture(s) that first built and then equipped the ship back on Earth, when Earth itself has become less than a memory to them? How will space change them, both biologically and psychologically? Is it possible to imaginatively explore the impact of imponderable, unexpected factors-a shipboard emergency, a previously unobserved physical phenomenon, a paradigm-changing discovery? This paper explores the evolution of the generation starship concept between 1940 and 1970, and the lessons that future planners of long-term space missions might glean from these imaginative efforts.

Turing instability in reaction-diffusion models on complex networks

NASA Astrophysics Data System (ADS)

Ide, Yusuke; Izuhara, Hirofumi; Machida, Takuya

2016-09-01

In this paper, the Turing instability in reaction-diffusion models defined on complex networks is studied. Here, we focus on three types of models which generate complex networks, i.e. the Erdős-Rényi, the Watts-Strogatz, and the threshold network models. From analysis of the Laplacian matrices of graphs generated by these models, we numerically reveal that stable and unstable regions of a homogeneous steady state on the parameter space of two diffusion coefficients completely differ, depending on the network architecture. In addition, we theoretically discuss the stable and unstable regions in the cases of regular enhanced ring lattices which include regular circles, and networks generated by the threshold network model when the number of vertices is large enough.

Improved resource use decisions and actions through remote sensing

NASA Technical Reports Server (NTRS)

Hill-Rowley, R.; Boylan, M.; Enslin, W.; Vlasin, R. D.

1975-01-01

Operational uses of remote sensing for improving management decisions and actions concerning resource uses are considered in terms of first generation, or direct-action; and second generation or indirect, delayed-action applications. From among applications completed during 1974-75, seven case studies are offered in illustration of the many contrasts which can be drawn between first and second generation application studies. These include: (1) multi-agency river basin planning; (2) corridor assessment and route location for highway location together with improvement of county-level planning decisions; (3) improving timber management practices; (4) enforcement of new state statutes; (5) county-wide open space preservation; (6) land value reappraisal relative to property tax equalization; and (7) optimizing agri-business processing plant locations.

Guidance, Navigation, and Control Considerations for Nuclear Thermal Propulsion

NASA Technical Reports Server (NTRS)

Houts, Michael G.; Mitchell, Doyce P.; Kim, Tony

2015-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation NTP system could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of a first generation NTP in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progress made under the NTP project could also help enable high performance fission power systems and Nuclear Electric Propulsion (NEP). Guidance, navigation, and control of NTP may have some unique but manageable characteristics.

Space Shuttle booster thrust imbalance analysis

NASA Technical Reports Server (NTRS)

Bailey, W. R.; Blackwell, D. L.

1985-01-01

An analysis of the Shuttle SRM thrust imbalance during the steady-state and tailoff portions of the boost phase of flight are presented. Results from flights STS-1 through STS-13 are included. A statistical analysis of the observed thrust imbalance data is presented. A 3 sigma thrust imbalance history versus time was generated from the observed data and is compared to the vehicle design requirements. The effect on Shuttle thrust imbalance from the use of replacement SRM segments is predicted. Comparisons of observed thrust imbalances with respect to predicted imbalances are presented for the two space shuttle flights which used replacement aft segments (STS-9 and STS-13).

ProSEDS Telemetry System Utilization of GPS Position Data for Transmitter Cycling

NASA Technical Reports Server (NTRS)

Kennedy, Paul; Sims, Herb

2000-01-01

NASA Marshall Space Flight Center will launch the Propulsive Small Expendable Deployer System (ProSEDS) space experiment in late 2000. ProSEDS will demonstrate the use of an electrodynamic tether propulsion system and will utilize a conducting wire tether to generate limited spacecraft power. This paper will provide an overview of the ProSEDS mission and will discuss the design, development and test of the spacecraft telemetry system which utilizes a custom designed GPS subsystem to determine spacecraft position relative to ground station location and to control transmitter on/off cycling based on spacecraft state vector and ground station visibility.

Terahertz plasmonic Bessel beamformer

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

Monnai, Yasuaki; Shinoda, Hiroyuki; Jahn, David

We experimentally demonstrate terahertz Bessel beamforming based on the concept of plasmonics. The proposed planar structure is made of concentric metallic grooves with a subwavelength spacing that couple to a point source to create tightly confined surface waves or spoof surface plasmon polaritons. Concentric scatterers periodically incorporated at a wavelength scale allow for launching the surface waves into free space to define a Bessel beam. The Bessel beam defined at 0.29 THz has been characterized through terahertz time-domain spectroscopy. This approach is capable of generating Bessel beams with planar structures as opposed to bulky axicon lenses and can be readily integratedmore » with solid-state terahertz sources.« less

Langley aerospace test highlights, 1988

NASA Technical Reports Server (NTRS)

1989-01-01

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Some of the significant tests which were performed during calendar year 1988 in Langley test facilities, a number of which are unique in the world are highlighted. Both the broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research are illustrated.

Extending existing structural identifiability analysis methods to mixed-effects models.

PubMed

Janzén, David L I; Jirstrand, Mats; Chappell, Michael J; Evans, Neil D

2018-01-01

The concept of structural identifiability for state-space models is expanded to cover mixed-effects state-space models. Two methods applicable for the analytical study of the structural identifiability of mixed-effects models are presented. The two methods are based on previously established techniques for non-mixed-effects models; namely the Taylor series expansion and the input-output form approach. By generating an exhaustive summary, and by assuming an infinite number of subjects, functions of random variables can be derived which in turn determine the distribution of the system's observation function(s). By considering the uniqueness of the analytical statistical moments of the derived functions of the random variables, the structural identifiability of the corresponding mixed-effects model can be determined. The two methods are applied to a set of examples of mixed-effects models to illustrate how they work in practice. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of helicopter flight dynamics through modeling and simulation of primary flight control actuation system

NASA Astrophysics Data System (ADS)

Nelson, Hunter Barton

A simplified second-order transfer function actuator model used in most flight dynamics applications cannot easily capture the effects of different actuator parameters. The present work integrates a nonlinear actuator model into a nonlinear state space rotorcraft model to determine the effect of actuator parameters on key flight dynamics. The completed actuator model was integrated with a swashplate kinematics where step responses were generated over a range of key hydraulic parameters. The actuator-swashplate system was then introduced into a nonlinear state space rotorcraft simulation where flight dynamics quantities such as bandwidth and phase delay analyzed. Frequency sweeps were simulated for unique actuator configurations using the coupled nonlinear actuator-rotorcraft system. The software package CIFER was used for system identification and compared directly to the linearized models. As the actuator became rate saturated, the effects on bandwidth and phase delay were apparent on the predicted handling qualities specifications.

A Numerical Approximation Framework for the Stochastic Linear Quadratic Regulator on Hilbert Spaces

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

Levajković, Tijana, E-mail: tijana.levajkovic@uibk.ac.at, E-mail: t.levajkovic@sf.bg.ac.rs; Mena, Hermann, E-mail: hermann.mena@uibk.ac.at; Tuffaha, Amjad, E-mail: atufaha@aus.edu

We present an approximation framework for computing the solution of the stochastic linear quadratic control problem on Hilbert spaces. We focus on the finite horizon case and the related differential Riccati equations (DREs). Our approximation framework is concerned with the so-called “singular estimate control systems” (Lasiecka in Optimal control problems and Riccati equations for systems with unbounded controls and partially analytic generators: applications to boundary and point control problems, 2004) which model certain coupled systems of parabolic/hyperbolic mixed partial differential equations with boundary or point control. We prove that the solutions of the approximate finite-dimensional DREs converge to the solutionmore » of the infinite-dimensional DRE. In addition, we prove that the optimal state and control of the approximate finite-dimensional problem converge to the optimal state and control of the corresponding infinite-dimensional problem.« less

Multivariable control of the Space Shuttle Remote Manipulator System using linearization by state feedback

NASA Technical Reports Server (NTRS)

Gettman, Chang-Ching L.; Adams, Neil; Bedrossian, Nazareth; Valavani, Lena

1993-01-01

This paper demonstrates an approach to nonlinear control system design that uses linearization by state feedback to allow faster maneuvering of payloads by the Shuttle Remote Manipulator System (SRMS). A nonlinear feedback law is defined to cancel the nonlinear plant dynamics so that a linear controller can be designed for the SRMS. First a nonlinear design model was generated via SIMULINK. This design model included nonlinear arm dynamics derived from the Lagrangian approach, linearized servo model, and linearized gearbox model. The current SRMS position hold controller was implemented on this system. Next, a trajectory was defined using a rigid body kinematics SRMS tool, KRMS. The maneuver was simulated. Finally, higher bandwidth controllers were developed. Results of the new controllers were compared with the existing SRMS automatic control modes for the Space Station Freedom Mission Build 4 Payload extended on the SRMS.

Human and Robotic Space Mission Use Cases for High-Performance Spaceflight Computing

NASA Technical Reports Server (NTRS)

Some, Raphael; Doyle, Richard; Bergman, Larry; Whitaker, William; Powell, Wesley; Johnson, Michael; Goforth, Montgomery; Lowry, Michael

2013-01-01

Spaceflight computing is a key resource in NASA space missions and a core determining factor of spacecraft capability, with ripple effects throughout the spacecraft, end-to-end system, and mission. Onboard computing can be aptly viewed as a "technology multiplier" in that advances provide direct dramatic improvements in flight functions and capabilities across the NASA mission classes, and enable new flight capabilities and mission scenarios, increasing science and exploration return. Space-qualified computing technology, however, has not advanced significantly in well over ten years and the current state of the practice fails to meet the near- to mid-term needs of NASA missions. Recognizing this gap, the NASA Game Changing Development Program (GCDP), under the auspices of the NASA Space Technology Mission Directorate, commissioned a study on space-based computing needs, looking out 15-20 years. The study resulted in a recommendation to pursue high-performance spaceflight computing (HPSC) for next-generation missions, and a decision to partner with the Air Force Research Lab (AFRL) in this development.

Alternative Approach to Vehicle Element Processing

NASA Technical Reports Server (NTRS)

Huether, Jacob E.; Otto, Albert E.

1995-01-01

The National Space Transportation Policy (NSTP), describes the challenge facing today's aerospace industry. 'Assuring reliable and affordable access to space through U.S. space transportation capabilities is a fundamental goal of the U.S. space program'. Experience from the Space Shuttle Program (SSP) tells us that launch and mission operations are responsible for approximately 45 % of the cost of each shuttle mission. Reducing these costs is critical to NSTP goals in the next generation launch vehicle. Based on this, an innovative alternative approach to vehicle element processing was developed with an emphasis on reduced launch costs. State-of-the-art upgrades to the launch processing system (LPS) will enhance vehicle ground operations. To carry this one step further, these upgrade could be implemented at various vehicle element manufacturing sites to ensure system compatibility between the manufacturing facility and the launch site. Design center vehicle stand alone testing will ensure system integrity resulting in minimized checkout and testing at the launch site. This paper will addresses vehicle test requirements, timelines and ground checkout procedures which enable concept implementation.

Electrochemical Disinfection Feasibility Assessment Materials Evaluation for the International Space Station

NASA Technical Reports Server (NTRS)

Rodriquez, Branelle; Shindo, David; Montgomery, Eliza

2013-01-01

The International Space Station (ISS) Program recognizes the risk of microbial contamination in their potable and non-potable water sources. The end of the Space Shuttle Program limited the ability to send up shock kits of biocides in the event of an outbreak. Currently, the United States Orbital Segment water system relies primarily on iodine to mitigate contamination concerns, which has been successful in remediating the small cases of contamination documented. However, a secondary method of disinfection is a necessary investment for future space flight. Over the past year, NASA Johnson Space Center has investigated the development of electrochemically generated systems for use on the ISS. These systems include: hydrogen peroxide, ozone, sodium hypochlorite, and peracetic acid. To use these biocides on deployed water systems, NASA must understand of the effect these biocides have on current ISS materials prior to proceeding forward with possible on-orbit applications. This paper will discuss the material testing that was conducted to assess the effects of the biocides on current ISS materials.

UrtheCast Second-Generation Earth Observation Sensors

NASA Astrophysics Data System (ADS)

Beckett, K.

2015-04-01

UrtheCast's Second-Generation state-of-the-art Earth Observation (EO) remote sensing platform will be hosted on the NASA segment of International Space Station (ISS). This platform comprises a high-resolution dual-mode (pushbroom and video) optical camera and a dual-band (X and L) Synthetic Aperture RADAR (SAR) instrument. These new sensors will complement the firstgeneration medium-resolution pushbroom and high-definition video cameras that were mounted on the Russian segment of the ISS in early 2014. The new cameras are expected to be launched to the ISS in late 2017 via the Space Exploration Technologies Corporation Dragon spacecraft. The Canadarm will then be used to install the remote sensing platform onto a CBM (Common Berthing Mechanism) hatch on Node 3, allowing the sensor electronics to be accessible from the inside of the station, thus limiting their exposure to the space environment and allowing for future capability upgrades. The UrtheCast second-generation system will be able to take full advantage of the strengths that each of the individual sensors offers, such that the data exploitation capabilities of the combined sensors is significantly greater than from either sensor alone. This represents a truly novel platform that will lead to significant advances in many other Earth Observation applications such as environmental monitoring, energy and natural resources management, and humanitarian response, with data availability anticipated to begin after commissioning is completed in early 2018.

NASA's Integrated Space Transportation Plan — 3 rd generation reusable launch vehicle technology update

NASA Astrophysics Data System (ADS)

Cook, Stephen; Hueter, Uwe

2003-08-01

NASA's Integrated Space Transportation Plan (ISTP) calls for investments in Space Shuttle safety upgrades, second generation Reusable Launch Vehicle (RLV) advanced development and third generation RLV and in-space research and technology. NASA's third generation launch systems are to be fully reusable and operation by 2025. The goals for third generation launch systems are to reduce cost by a factor of 100 and improve safety by a factor of 10,000 over current systems. The Advanced Space Transportation Program Office (ASTP) at NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop third generation space transportation technologies. The Hypersonics Investment Area, part of ASTP, is developing the third generation launch vehicle technologies in two main areas, propulsion and airframes. The program's major investment is in hypersonic airbreathing propulsion since it offers the greatest potential for meeting the third generation launch vehicles. The program will mature the technologies in three key propulsion areas, scramjets, rocket-based combined cycle and turbine-based combination cycle. Ground and flight propulsion tests are being planned for the propulsion technologies. Airframe technologies will be matured primarily through ground testing. This paper describes NASA's activities in hypersonics. Current programs, accomplishments, future plans and technologies that are being pursued by the Hypersonics Investment Area under the Advanced Space Transportation Program Office will be discussed.

Determination of Thermal State of Charge in Solar Heat Receivers

NASA Technical Reports Server (NTRS)

Glakpe, E. K.; Cannon, J. N.; Hall, C. A., III; Grimmett, I. W.

1996-01-01

The research project at Howard University seeks to develop analytical and numerical capabilities to study heat transfer and fluid flow characteristics, and the prediction of the performance of solar heat receivers for space applications. Specifically, the study seeks to elucidate the effects of internal and external thermal radiation, geometrical and applicable dimensionless parameters on the overall heat transfer in space solar heat receivers. Over the last year, a procedure for the characterization of the state-of-charge (SOC) in solar heat receivers for space applications has been developed. By identifying the various factors that affect the SOC, a dimensional analysis is performed resulting in a number of dimensionless groups of parameters. Although not accomplished during the first phase of the research, data generated from a thermal simulation program can be used to determine values of the dimensionless parameters and the state-of-charge and thereby obtain a correlation for the SOC. The simulation program selected for the purpose is HOTTube, a thermal numerical computer code based on a transient time-explicit, axisymmetric model of the total solar heat receiver. Simulation results obtained with the computer program are presented the minimum and maximum insolation orbits. In the absence of any validation of the code with experimental data, results from HOTTube appear reasonable qualitatively in representing the physical situations modeled.

Model reduction and frequency residuals for a robust estimation of nonlinearities in subspace identification

NASA Astrophysics Data System (ADS)

De Filippis, G.; Noël, J. P.; Kerschen, G.; Soria, L.; Stephan, C.

2017-09-01

The introduction of the frequency-domain nonlinear subspace identification (FNSI) method in 2013 constitutes one in a series of recent attempts toward developing a realistic, first-generation framework applicable to complex structures. If this method showed promising capabilities when applied to academic structures, it is still confronted with a number of limitations which needs to be addressed. In particular, the removal of nonphysical poles in the identified nonlinear models is a distinct challenge. In the present paper, it is proposed as a first contribution to operate directly on the identified state-space matrices to carry out spurious pole removal. A modal-space decomposition of the state and output matrices is examined to discriminate genuine from numerical poles, prior to estimating the extended input and feedthrough matrices. The final state-space model thus contains physical information only and naturally leads to nonlinear coefficients free of spurious variations. Besides spurious variations due to nonphysical poles, vibration modes lying outside the frequency band of interest may also produce drifts of the nonlinear coefficients. The second contribution of the paper is to include residual terms, accounting for the existence of these modes. The proposed improved FNSI methodology is validated numerically and experimentally using a full-scale structure, the Morane-Saulnier Paris aircraft.

State-space model with deep learning for functional dynamics estimation in resting-state fMRI.

PubMed

Suk, Heung-Il; Wee, Chong-Yaw; Lee, Seong-Whan; Shen, Dinggang

2016-04-01

Studies on resting-state functional Magnetic Resonance Imaging (rs-fMRI) have shown that different brain regions still actively interact with each other while a subject is at rest, and such functional interaction is not stationary but changes over time. In terms of a large-scale brain network, in this paper, we focus on time-varying patterns of functional networks, i.e., functional dynamics, inherent in rs-fMRI, which is one of the emerging issues along with the network modelling. Specifically, we propose a novel methodological architecture that combines deep learning and state-space modelling, and apply it to rs-fMRI based Mild Cognitive Impairment (MCI) diagnosis. We first devise a Deep Auto-Encoder (DAE) to discover hierarchical non-linear functional relations among regions, by which we transform the regional features into an embedding space, whose bases are complex functional networks. Given the embedded functional features, we then use a Hidden Markov Model (HMM) to estimate dynamic characteristics of functional networks inherent in rs-fMRI via internal states, which are unobservable but can be inferred from observations statistically. By building a generative model with an HMM, we estimate the likelihood of the input features of rs-fMRI as belonging to the corresponding status, i.e., MCI or normal healthy control, based on which we identify the clinical label of a testing subject. In order to validate the effectiveness of the proposed method, we performed experiments on two different datasets and compared with state-of-the-art methods in the literature. We also analyzed the functional networks learned by DAE, estimated the functional connectivities by decoding hidden states in HMM, and investigated the estimated functional connectivities by means of a graph-theoretic approach. Copyright © 2016 Elsevier Inc. All rights reserved.

State-space model with deep learning for functional dynamics estimation in resting-state fMRI

PubMed Central

Suk, Heung-Il; Wee, Chong-Yaw; Lee, Seong-Whan; Shen, Dinggang

2017-01-01

Studies on resting-state functional Magnetic Resonance Imaging (rs-fMRI) have shown that different brain regions still actively interact with each other while a subject is at rest, and such functional interaction is not stationary but changes over time. In terms of a large-scale brain network, in this paper, we focus on time-varying patterns of functional networks, i.e., functional dynamics, inherent in rs-fMRI, which is one of the emerging issues along with the network modelling. Specifically, we propose a novel methodological architecture that combines deep learning and state-space modelling, and apply it to rs-fMRI based Mild Cognitive Impairment (MCI) diagnosis. We first devise a Deep Auto-Encoder (DAE) to discover hierarchical non-linear functional relations among regions, by which we transform the regional features into an embedding space, whose bases are complex functional networks. Given the embedded functional features, we then use a Hidden Markov Model (HMM) to estimate dynamic characteristics of functional networks inherent in rs-fMRI via internal states, which are unobservable but can be inferred from observations statistically. By building a generative model with an HMM, we estimate the likelihood of the input features of rs-fMRI as belonging to the corresponding status, i.e., MCI or normal healthy control, based on which we identify the clinical label of a testing subject. In order to validate the effectiveness of the proposed method, we performed experiments on two different datasets and compared with state-of-the-art methods in the literature. We also analyzed the functional networks learned by DAE, estimated the functional connectivities by decoding hidden states in HMM, and investigated the estimated functional connectivities by means of a graph-theoretic approach. PMID:26774612

Gaussian entanglement distribution via satellite

NASA Astrophysics Data System (ADS)

Hosseinidehaj, Nedasadat; Malaney, Robert

2015-02-01

In this work we analyze three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme, the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the tradeoff between space-based engineering complexity and the rate of ground-station entanglement generation.

Dynamically tunable interface states in 1D graphene-embedded photonic crystal heterostructure

NASA Astrophysics Data System (ADS)

Huang, Zhao; Li, Shuaifeng; Liu, Xin; Zhao, Degang; Ye, Lei; Zhu, Xuefeng; Zang, Jianfeng

2018-03-01

Optical interface states exhibit promising applications in nonlinear photonics, low-threshold lasing, and surface-wave assisted sensing. However, the further application of interface states in configurable optics is hindered by their limited tunability. Here, we demonstrate a new approach to generate dynamically tunable and angle-resolved interface states using graphene-embedded photonic crystal (GPC) heterostructure device. By combining the GPC structure design with in situ electric doping of graphene, a continuously tunable interface state can be obtained and its tuning range is as wide as the full bandgap. Moreover, the exhibited tunable interface states offer a possibility to study the correspondence between space and time characteristics of light, which is beyond normal incident conditions. Our strategy provides a new way to design configurable devices with tunable optical states for various advanced optical applications such as beam splitter and dynamically tunable laser.

A solid state tunable laser for resonance measurements of atmospheric sodium

NASA Technical Reports Server (NTRS)

Philbrick, C. R.; Bufton, J. L.; Gardner, C. S.

1985-01-01

The measurement of wave dynamics in the upper mesosphere using a solid-state laser to excite the resonance fluorescence line of sodium is examined. Two Nd:YAG lasers are employed to produce the sodium resonance line. The method involves mixing the 1064 nm radiation with that from a second Nd:YAG operating at 1319 nm in a nonlinear infrared crystal to directly produce 589 nm radiation by sum frequency generation. The use of the transmitter to measure the sodium layer from the Space Shuttle Platform is proposed. A diagram of the laser transmitter is presented.

Complex Ordered Patterns in Mechanical Instability Induced Geometrically Frustrated Triangular Cellular Structures

NASA Astrophysics Data System (ADS)

Kang, Sung Hoon; Shan, Sicong; Košmrlj, Andrej; Noorduin, Wim L.; Shian, Samuel; Weaver, James C.; Clarke, David R.; Bertoldi, Katia

2014-03-01

Geometrical frustration arises when a local order cannot propagate throughout the space because of geometrical constraints. This phenomenon plays a major role in many systems leading to disordered ground-state configurations. Here, we report a theoretical and experimental study on the behavior of buckling-induced geometrically frustrated triangular cellular structures. To our surprise, we find that buckling induces complex ordered patterns which can be tuned by controlling the porosity of the structures. Our analysis reveals that the connected geometry of the cellular structure plays a crucial role in the generation of ordered states in this frustrated system.

Base norms and discrimination of generalized quantum channels

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

Jenčová, A.

2014-02-15

We introduce and study norms in the space of hermitian matrices, obtained from base norms in positively generated subspaces. These norms are closely related to discrimination of so-called generalized quantum channels, including quantum states, channels, and networks. We further introduce generalized quantum decision problems and show that the maximal average payoffs of decision procedures are again given by these norms. We also study optimality of decision procedures, in particular, we obtain a necessary and sufficient condition under which an optimal 1-tester for discrimination of quantum channels exists, such that the input state is maximally entangled.

Method of generating a surface mesh

DOEpatents

Shepherd, Jason F [Albuquerque, NM; Benzley, Steven [Provo, UT; Grover, Benjamin T [Tracy, CA

2008-03-04

A method and machine-readable medium provide a technique to generate and modify a quadrilateral finite element surface mesh using dual creation and modification. After generating a dual of a surface (mesh), a predetermined algorithm may be followed to generate and modify a surface mesh of quadrilateral elements. The predetermined algorithm may include the steps of generating two-dimensional cell regions in dual space, determining existing nodes in primal space, generating new nodes in the dual space, and connecting nodes to form the quadrilateral elements (faces) for the generated and modifiable surface mesh.

High-Pressure Synthesis: A New Frontier in the Search for Next-Generation Intermetallic Compounds.

PubMed

Walsh, James P S; Freedman, Danna E

2018-06-19

The application of high pressure adds an additional dimension to chemical phase space, opening up an unexplored expanse bearing tremendous potential for discovery. Our continuing mission is to explore this new frontier, to seek out new intermetallic compounds and new solid-state bonding. Simple binary elemental systems, in particular those composed of pairs of elements that do not form compounds under ambient pressures, can yield novel crystalline phases under compression. Thus, high-pressure synthesis can provide access to solid-state compounds that cannot be formed with traditional thermodynamic methods. An emerging approach for the rapid exploration of composition-pressure-temperature phase space is the use of hand-held high-pressure devices known as diamond anvil cells (DACs). These devices were originally developed by geologists as a way to study minerals under conditions relevant to the earth's interior, but they possess a host of capabilities that make them ideal for high-pressure solid-state synthesis. Of particular importance, they offer the capability for in situ spectroscopic and diffraction measurements, thereby enabling continuous reaction monitoring-a powerful capability for solid-state synthesis. In this Account, we provide an overview of this approach in the context of research we have performed in the pursuit of new intermetallic compounds. We start with a discussion of pressure as a fundamental experimental variable that enables the formation of intermetallic compounds that cannot be isolated under ambient conditions. We then introduce the DAC apparatus and explain how it can be repurposed for use as a synthetic vessel with which to explore this phase space, going to extremes of pressure where no chemist has gone before. The remainder of the Account is devoted to discussions of recent experiments we have performed with this approach that have led to the discovery of novel intermetallic compounds in the Fe-Bi, Cu-Bi, and Ni-Bi systems, with a focus on the cutting-edge methods that made these experiments possible. We review the use of in situ laser heating at high pressure, which led to the discovery of FeBi 2 , the first binary intermetallic compound in the Fe-Bi system. Our work in the Cu-Bi system is described in the context of in situ experiments carried out in the DAC to map its high-pressure phase space, which revealed two intermetallic phases (Cu 11 Bi 7 and CuBi). Finally, we review the discovery of β-NiBi, a novel high-pressure phase in the Ni-Bi system. We hope that this Account will inspire the next generation of solid-state chemists to boldly explore high-pressure phase space.

Space Weather Model Testing And Validation At The Community Coordinated Modeling Center

NASA Astrophysics Data System (ADS)

Hesse, M.; Kuznetsova, M.; Rastaetter, L.; Falasca, A.; Keller, K.; Reitan, P.

The Community Coordinated Modeling Center (CCMC) is a multi-agency partner- ship aimed at the creation of next generation space weather models. The goal of the CCMC is to undertake the research and developmental work necessary to substantially increase the present-day modeling capability for space weather purposes, and to pro- vide models for transition to the rapid prototyping centers at the space weather forecast centers. This goal requires close collaborations with and substantial involvement of the research community. The physical regions to be addressed by CCMC-related activities range from the solar atmosphere to the Earth's upper atmosphere. The CCMC is an integral part of NASA's Living With aStar initiative, of the National Space Weather Program Implementation Plan, and of the Department of Defense Space Weather Tran- sition Plan. CCMC includes a facility at NASA Goddard Space Flight Center, as well as distributed computing facilities provided by the Air Force. CCMC also provides, to the research community, access to state-of-the-art space research models. In this paper we will provide updates on CCMC status, on current plans, research and devel- opment accomplishments and goals, and on the model testing and validation process undertaken as part of the CCMC mandate.

Hybrid Reduced Order Modeling Algorithms for Reactor Physics Calculations

NASA Astrophysics Data System (ADS)

Bang, Youngsuk

Reduced order modeling (ROM) has been recognized as an indispensable approach when the engineering analysis requires many executions of high fidelity simulation codes. Examples of such engineering analyses in nuclear reactor core calculations, representing the focus of this dissertation, include the functionalization of the homogenized few-group cross-sections in terms of the various core conditions, e.g. burn-up, fuel enrichment, temperature, etc. This is done via assembly calculations which are executed many times to generate the required functionalization for use in the downstream core calculations. Other examples are sensitivity analysis used to determine important core attribute variations due to input parameter variations, and uncertainty quantification employed to estimate core attribute uncertainties originating from input parameter uncertainties. ROM constructs a surrogate model with quantifiable accuracy which can replace the original code for subsequent engineering analysis calculations. This is achieved by reducing the effective dimensionality of the input parameter, the state variable, or the output response spaces, by projection onto the so-called active subspaces. Confining the variations to the active subspace allows one to construct an ROM model of reduced complexity which can be solved more efficiently. This dissertation introduces a new algorithm to render reduction with the reduction errors bounded based on a user-defined error tolerance which represents the main challenge of existing ROM techniques. Bounding the error is the key to ensuring that the constructed ROM models are robust for all possible applications. Providing such error bounds represents one of the algorithmic contributions of this dissertation to the ROM state-of-the-art. Recognizing that ROM techniques have been developed to render reduction at different levels, e.g. the input parameter space, the state space, and the response space, this dissertation offers a set of novel hybrid ROM algorithms which can be readily integrated into existing methods and offer higher computational efficiency and defendable accuracy of the reduced models. For example, the snapshots ROM algorithm is hybridized with the range finding algorithm to render reduction in the state space, e.g. the flux in reactor calculations. In another implementation, the perturbation theory used to calculate first order derivatives of responses with respect to parameters is hybridized with a forward sensitivity analysis approach to render reduction in the parameter space. Reduction at the state and parameter spaces can be combined to render further reduction at the interface between different physics codes in a multi-physics model with the accuracy quantified in a similar manner to the single physics case. Although the proposed algorithms are generic in nature, we focus here on radiation transport models used in support of the design and analysis of nuclear reactor cores. In particular, we focus on replacing the traditional assembly calculations by ROM models to facilitate the generation of homogenized cross-sections for downstream core calculations. The implication is that assembly calculations could be done instantaneously therefore precluding the need for the expensive evaluation of the few-group cross-sections for all possible core conditions. Given the generic natures of the algorithms, we make an effort to introduce the material in a general form to allow non-nuclear engineers to benefit from this work.

GPS & Galileo. Friendly Foes?

DTIC Science & Technology

2007-04-01

some of their data, others employ different techniques. United States defense contractor Lockheed Martin developed an anti-jam GPS receiver in 2000 for...Europe in a New Generation of Satellite Navigation Services,” European Commission (9 Feb 1999): 16. 25. Ibid. 26. Anne Jolis , “Problems Run Rampant...European Outer Space,” Euro Topics (19 March 2007), found at http://www.eurotopics.net/en/presseschau/archiv/archiv_dossier/DOSSIER15435. 40. Jolis

TMS installation at A-1 Test Stand

NASA Image and Video Library

2010-03-03

A new thrust measurement system is lifted onto the A-1 Test Stand deck at NASA's John C. Stennis Space Center in preparation for its installation. The new system is a state-of-the-art upgrade for the testing structure, which is being prepared for testing of next-generation rocket engines. The system was fabricated by Thrust Measurement Systems in Illinois at a cost of about $3.5 million.

Physics-Based Robot Motion Planning in Dynamic Multi-Body Environments

DTIC Science & Technology

2010-05-10

be actuated by external influences and interactions, such as being carried or pushed. Foreign-controlled bodies are actively actuated, but by external...from the action space A. How this action is generated can strongly influence the overall behavior and performance of our planner and will be discussed in...evolving game-state and unpredictable player -input), an animator cannot manually adjust these controls in advance. The planning approaches introduced in

Field quantization and squeezed states generation in resonators with time-dependent parameters

NASA Technical Reports Server (NTRS)

Dodonov, V. V.; Klimov, A. B.; Nikonov, D. E.

1992-01-01

The problem of electromagnetic field quantization is usually considered in textbooks under the assumption that the field occupies some empty box. The case when a nonuniform time-dependent dielectric medium is confined in some space region with time-dependent boundaries is studied. The basis of the subsequent consideration is the system of Maxwell's equations in linear passive time-dependent dielectric and magnetic medium without sources.

Exactly solvable quantum cosmologies from two killing field reductions of general relativity

NASA Astrophysics Data System (ADS)

Husain, Viqar; Smolin, Lee

1989-11-01

An exact and, possibly, general solution to the quantum constraints is given for the sector of general relativity containing cosmological solutions with two space-like, commuting, Killing fields. The dynamics of these model space-times, which are known as Gowdy space-times, is formulated in terms of Ashtekar's new variables. The quantization is done by using the recently introduced self-dual and loop representations. On the classical phase space we find four explicit physical observables, or constants of motion, which generate a GL(2) symmetry group on the space of solutions. In the loop representations we find that a complete description of the physical state space, consisting of the simultaneous solutions to all of the constraints, is given in terms of the equivalence classes, under Diff(S1), of a pair of densities on the circle. These play the same role that the link classes play in the loop representation solution to the full 3+1 theory. An infinite dimensional algebra of physical observables is found on the physical state space, which is a GL(2) loop algebra. In addition, by freezing the local degrees of freedom of the model, we find a finite dimensional quantum system which describes a set of degenerate quantum cosmologies on T3 in which the length of one of the S1's has gone to zero, while the area of the remaining S1×S1 is quantized in units of the Planck area. The quantum kinematics of this sector of the model is identical to that of a one-plaquette SU(2) lattice gauge theory.

ClustENM: ENM-Based Sampling of Essential Conformational Space at Full Atomic Resolution

PubMed Central

Kurkcuoglu, Zeynep; Bahar, Ivet; Doruker, Pemra

2016-01-01

Accurate sampling of conformational space and, in particular, the transitions between functional substates has been a challenge in molecular dynamic (MD) simulations of large biomolecular systems. We developed an Elastic Network Model (ENM)-based computational method, ClustENM, for sampling large conformational changes of biomolecules with various sizes and oligomerization states. ClustENM is an iterative method that combines ENM with energy minimization and clustering steps. It is an unbiased technique, which requires only an initial structure as input, and no information about the target conformation. To test the performance of ClustENM, we applied it to six biomolecular systems: adenylate kinase (AK), calmodulin, p38 MAP kinase, HIV-1 reverse transcriptase (RT), triosephosphate isomerase (TIM), and the 70S ribosomal complex. The generated ensembles of conformers determined at atomic resolution show good agreement with experimental data (979 structures resolved by X-ray and/or NMR) and encompass the subspaces covered in independent MD simulations for TIM, p38, and RT. ClustENM emerges as a computationally efficient tool for characterizing the conformational space of large systems at atomic detail, in addition to generating a representative ensemble of conformers that can be advantageously used in simulating substrate/ligand-binding events. PMID:27494296

General Purpose Data-Driven Online System Health Monitoring with Applications to Space Operations

NASA Technical Reports Server (NTRS)

Iverson, David L.; Spirkovska, Lilly; Schwabacher, Mark

2010-01-01

Modern space transportation and ground support system designs are becoming increasingly sophisticated and complex. Determining the health state of these systems using traditional parameter limit checking, or model-based or rule-based methods is becoming more difficult as the number of sensors and component interactions grows. Data-driven monitoring techniques have been developed to address these issues by analyzing system operations data to automatically characterize normal system behavior. System health can be monitored by comparing real-time operating data with these nominal characterizations, providing detection of anomalous data signatures indicative of system faults, failures, or precursors of significant failures. The Inductive Monitoring System (IMS) is a general purpose, data-driven system health monitoring software tool that has been successfully applied to several aerospace applications and is under evaluation for anomaly detection in vehicle and ground equipment for next generation launch systems. After an introduction to IMS application development, we discuss these NASA online monitoring applications, including the integration of IMS with complementary model-based and rule-based methods. Although the examples presented in this paper are from space operations applications, IMS is a general-purpose health-monitoring tool that is also applicable to power generation and transmission system monitoring.

Creating Next Generation Teacher Preparation Programs to Support Implementation of the Next Generation Science Standards and Common Core State Standards in K-12 Schools: An Opportunity for the Earth and Space Sciences

NASA Astrophysics Data System (ADS)

Geary, E. E.; Egger, A. E.; Julin, S.; Ronca, R.; Vokos, S.; Ebert, E.; Clark-Blickenstaff, J.; Nollmeyer, G.

2015-12-01

A consortium of two and four year Washington State Colleges and Universities in partnership with Washington's Office of the Superintendent of Public Instruction (OSPI), the Teachers of Teachers of Science, and Teachers of Teachers of Mathematics, and other key stakeholders, is currently working to improve science and mathematics learning for all Washington State students by creating a new vision for STEM teacher preparation in Washington State aligned with the Next Generation Science Standards (NGSS) and the Common Core State Standards (CCSS) in Mathematics and Language Arts. Specific objectives include: (1) strengthening elementary and secondary STEM Teacher Preparation courses and curricula, (2) alignment of STEM teacher preparation programs across Washington State with the NGSS and CCSS, (3) development of action plans to support implementation of STEM Teacher Preparation program improvement at Higher Education Institutions (HEIs) across the state, (4) stronger collaborations between HEIs, K-12 schools, government agencies, Non-Governmental Organizations, and STEM businesses, involved in the preparation of preservice STEM teachers, (5) new teacher endorsements in Computer Science and Engineering, and (6) development of a proto-type model for rapid, adaptable, and continuous improvement of STEM teacher preparation programs. A 2015 NGSS gap analysis of teacher preparation programs across Washington State indicates relatively good alignment of courses and curricula with NGSS Disciplinary Core Ideas and Scientific practices, but minimal alignment with NGSS Engineering practices and Cross Cutting Concepts. Likewise, Computer Science and Sustainability ideas and practices are not well represented in current courses and curricula. During the coming year teams of STEM faculty, education faculty and administrators will work collaboratively to develop unique action plans for aligning and improving STEM teacher preparation courses and curricula at their institutions.

Approximate symmetries in atomic nuclei from a large-scale shell-model perspective

NASA Astrophysics Data System (ADS)

Launey, K. D.; Draayer, J. P.; Dytrych, T.; Sun, G.-H.; Dong, S.-H.

2015-05-01

In this paper, we review recent developments that aim to achieve further understanding of the structure of atomic nuclei, by capitalizing on exact symmetries as well as approximate symmetries found to dominate low-lying nuclear states. The findings confirm the essential role played by the Sp(3, ℝ) symplectic symmetry to inform the interaction and the relevant model spaces in nuclear modeling. The significance of the Sp(3, ℝ) symmetry for a description of a quantum system of strongly interacting particles naturally emerges from the physical relevance of its generators, which directly relate to particle momentum and position coordinates, and represent important observables, such as, the many-particle kinetic energy, the monopole operator, the quadrupole moment and the angular momentum. We show that it is imperative that shell-model spaces be expanded well beyond the current limits to accommodate particle excitations that appear critical to enhanced collectivity in heavier systems and to highly-deformed spatial structures, exemplified by the second 0+ state in 12C (the challenging Hoyle state) and 8Be. While such states are presently inaccessible by large-scale no-core shell models, symmetry-based considerations are found to be essential.

Nuclear Cryogenic Propulsion Stage

NASA Technical Reports Server (NTRS)

Houts, Michael G.; Borowski, S. K.; George, J. A.; Kim, T.; Emrich, W. J.; Hickman, R. R.; Broadway, J. W.; Gerrish, H. P.; Adams, R. B.

2012-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on NTP could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of the NCPS in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progress made under the NCPS project could help enable both advanced NTP and advanced NEP.

Quantization of spinor fields. III. Fermions on coherent (Bose) domains

NASA Astrophysics Data System (ADS)

Garbaczewski, Piotr

1983-02-01

A formulation of the c-number classics-quanta correspondence rule for spinor systems requires all elements of the quantum field algebra to be expanded into power series with respect to the generators of the canonical commutation relation (CCR) algebra. On the other hand, the asymptotic completeness demand would result in the (Haag) expansions with respect to the canonical anticommutation relation (CAR) generators. We establish the conditions under which the above correspondence rule can be reconciled with the existence of Haag expansions in terms of asymptotic free Fermi fields. Then, the CAR become represented on the state space of the Bose (CCR) system.

Lightweight Integrated Solar Array and Transceiver. [Improving Electrical Power and Communication Capabilities in Small Spacecraft

NASA Technical Reports Server (NTRS)

Carr, John; Martinez, Andres; Petro, Andrew

2015-01-01

The Lightweight Integrated Solar Array and Transceiver (LISA-T) project will leverage several existing and on-going efforts at Marshall Space Flight Center (MSFC) for the design, development, fabrication, and test of a launch stowed, orbit deployed structure on which thin-film photovoltaics for power generation and antenna elements for communication, are embedded. Photovoltaics is a method for converting solar energy into electricity using semiconductor materials. The system will provide higher power generation with a lower mass, smaller stowage volume, and lower cost than the state of the art solar arrays, while simultaneously enabling deployable antenna concepts.

A generative, probabilistic model of local protein structure.

PubMed

Boomsma, Wouter; Mardia, Kanti V; Taylor, Charles C; Ferkinghoff-Borg, Jesper; Krogh, Anders; Hamelryck, Thomas

2008-07-01

Despite significant progress in recent years, protein structure prediction maintains its status as one of the prime unsolved problems in computational biology. One of the key remaining challenges is an efficient probabilistic exploration of the structural space that correctly reflects the relative conformational stabilities. Here, we present a fully probabilistic, continuous model of local protein structure in atomic detail. The generative model makes efficient conformational sampling possible and provides a framework for the rigorous analysis of local sequence-structure correlations in the native state. Our method represents a significant theoretical and practical improvement over the widely used fragment assembly technique by avoiding the drawbacks associated with a discrete and nonprobabilistic approach.

The Deep Space Network. An instrument for radio navigation of deep space probes

NASA Technical Reports Server (NTRS)

Renzetti, N. A.; Jordan, J. F.; Berman, A. L.; Wackley, J. A.; Yunck, T. P.

1982-01-01

The Deep Space Network (DSN) network configurations used to generate the navigation observables and the basic process of deep space spacecraft navigation, from data generation through flight path determination and correction are described. Special emphasis is placed on the DSN Systems which generate the navigation data: the DSN Tracking and VLBI Systems. In addition, auxiliary navigational support functions are described.

Test tools and test data for the future EUMETSAT EPS-SG platform

NASA Astrophysics Data System (ADS)

Khlystova, Iryna; Sunda, Michela

2017-04-01

The EUMETSAT Polar System - Second Generation (EPS-SG) represents Europe's contribution to the future Joint Polar System (JPS), which is planned to be established together with the National Oceanic and Atmospheric Administration (NOAA) of the United States, following on from the Initial Joint Polar System (IJPS). Due to its global coverage and the variety of passive and active sensors on the EPS-SG platform, a significant positive impact on Numerical Weather Prediction (NWP) can be expected for all forecasts based on NWP in the 2020-2040 time frame. It will increase direct socio-economic benefits to Member States and leverage additional benefits through its integration into the JPS and cooperation in the context of CGMS and WMO. For the EUMETSAT will develop the EPS-SG overall system of satellites and the Overall Ground Segment (OGS) and be responsible for the Payload Data Acquisition and Processing (PDAP) system. This will include all the functionality dedicated to the L0, L1 and L2 Operational Processor, for generation of the near-real time L1 and L2 mission central products. Also the European Space Agency will develop the EPS-SG satellites and a number of instruments, with CNES and DLR playing a key role. The general processing chain should be in place and be extensively tested before the first data set is sent from the space platform to the ground. For this, numerous test tools, such as satellite data simulators (IDS) and processors prototypes (GPPs and IPPs) need to be developed and operated before the launch of the satellites. EUMETSAT cooperated with several European agencies in order to provide all the testing items in time. Here, we present the insight into the EPS-SG the logic of the test tools for the generation of the test data and provide insights into the modern space-based mission planning and preparation activities.

Full-potential multiple scattering theory with space-filling cells for bound and continuum states.

PubMed

Hatada, Keisuke; Hayakawa, Kuniko; Benfatto, Maurizio; Natoli, Calogero R

2010-05-12

We present a rigorous derivation of a real-space full-potential multiple scattering theory (FP-MST) that is free from the drawbacks that up to now have impaired its development (in particular the need to expand cell shape functions in spherical harmonics and rectangular matrices), valid both for continuum and bound states, under conditions for space partitioning that are not excessively restrictive and easily implemented. In this connection we give a new scheme to generate local basis functions for the truncated potential cells that is simple, fast, efficient, valid for any shape of the cell and reduces to the minimum the number of spherical harmonics in the expansion of the scattering wavefunction. The method also avoids the need for saturating 'internal sums' due to the re-expansion of the spherical Hankel functions around another point in space (usually another cell center). Thus this approach provides a straightforward extension of MST in the muffin-tin (MT) approximation, with only one truncation parameter given by the classical relation l(max) = kR(b), where k is the electron wavevector (either in the excited or ground state of the system under consideration) and R(b) is the radius of the bounding sphere of the scattering cell. Moreover, the scattering path operator of the theory can be found in terms of an absolutely convergent procedure in the l(max) --> ∞ limit. Consequently, this feature provides a firm ground for the use of FP-MST as a viable method for electronic structure calculations and makes possible the computation of x-ray spectroscopies, notably photo-electron diffraction, absorption and anomalous scattering among others, with the ease and versatility of the corresponding MT theory. Some numerical applications of the theory are presented, both for continuum and bound states.

Spanwise Spacing Effects on the Initial Structure and Decay of Axial Vortices

NASA Technical Reports Server (NTRS)

Wendt, B. J.; Reichert, B. A.

1996-01-01

The initial structure and axial decay of an array of streamwise vortices embedded in a turbulent pipe boundary layer is experimentally investigated. The vortices are shed in counter-rotating fashion from an array of equally-spaced symmetric airfoil vortex generators. Vortex structure is quantified in terms of crossplane circulation and peak streamwise vorticity. Flow conditions are subsonic and incompressible. The focus of this study is on the effect of the initial spacing between the parent vortex generators. Arrays with vortex generators spaced at 15 and 30 degrees apart are considered. When the spacing between vortex generators is decreased the circulation and peak vorticity of the shed vortices increases. Analysis indicates this strengthening results from regions of fluid acceleration in the vicinity of the vortex generator array. Decreased spacing between the constituent vortices also produces increased rates of circulation and peak vorticity decay.

Failing States as Epidemiologic Risk Zones: Implications for Global Health Security.

PubMed

Hirschfeld, Katherine

Failed states commonly experience health and mortality crises that include outbreaks of infectious disease, violent conflict, reductions in life expectancy, and increased infant and maternal mortality. This article draws from recent research in political science, security studies, and international relations to explore how the process of state failure generates health declines and outbreaks of infectious disease. The key innovation of this model is a revised definition of "the state" as a geographically dynamic rather than static political space. This makes it easier to understand how phases of territorial contraction, collapse, and regeneration interrupt public health programs, destabilize the natural environment, reduce human security, and increase risks of epidemic infectious disease and other humanitarian crises. Better understanding of these dynamics will help international health agencies predict and prepare for future health and mortality crises created by failing states.

Trapping effect of metal nanoparticle mono- and multilayer in the organic field-effect transistor

NASA Astrophysics Data System (ADS)

Lee, Keanchuan; Weis, Martin; Lin, Jack; Taguchi, Dai; Majková, Eva; Manaka, Takaaki; Iwamoto, Mitsumasa

2011-03-01

The effect of silver nanoparticles self-assembled monolayer (Ag NPs SAM) on charge transport in pentacene organic field-effect transistors (OFET) was investigated by both steady-state and transient-state methods, which are current-voltage measurements in steady-state and time-resolved microscopic (TRM) second harmonic generation (SHG) in transient-state, respectively. The analysis of electronic properties revealed that OFET with SAM exhibited significant charge trapping effect due to the space-charge field formed by immobile charges. Lower transient-state mobility was verified by the direct probing of carrier motion by TRM-SHG technique. It was shown that the trapping effect rises together with increase of SAM layers suggesting the presence of traps in the bulk of NP films. The model based on the electrostatic charge barrier is suggested to explain the phenomenon.

The Argos-CLS Kalman Filter: Error Structures and State-Space Modelling Relative to Fastloc GPS Data.

PubMed

Lowther, Andrew D; Lydersen, Christian; Fedak, Mike A; Lovell, Phil; Kovacs, Kit M

2015-01-01

Understanding how an animal utilises its surroundings requires its movements through space to be described accurately. Satellite telemetry is the only means of acquiring movement data for many species however data are prone to varying amounts of spatial error; the recent application of state-space models (SSMs) to the location estimation problem have provided a means to incorporate spatial errors when characterising animal movements. The predominant platform for collecting satellite telemetry data on free-ranging animals, Service Argos, recently provided an alternative Doppler location estimation algorithm that is purported to be more accurate and generate a greater number of locations that its predecessor. We provide a comprehensive assessment of this new estimation process performance on data from free-ranging animals relative to concurrently collected Fastloc GPS data. Additionally, we test the efficacy of three readily-available SSM in predicting the movement of two focal animals. Raw Argos location estimates generated by the new algorithm were greatly improved compared to the old system. Approximately twice as many Argos locations were derived compared to GPS on the devices used. Root Mean Square Errors (RMSE) for each optimal SSM were less than 4.25 km with some producing RMSE of less than 2.50 km. Differences in the biological plausibility of the tracks between the two focal animals used to investigate the utility of SSM highlights the importance of considering animal behaviour in movement studies. The ability to reprocess Argos data collected since 2008 with the new algorithm should permit questions of animal movement to be revisited at a finer resolution.

Summary of 2006 to 2010 FPMU Measurements of International Space Station Frame Potential Variations

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Wright, Kenneth H., Jr.; Chandler, Michael O.; Coffey, Victoria N.; Craven, Paul D.; Schneider, Todd A.; Parker, Linda N.; Ferguson, Dale C.; Koontz, Steve L.; Alred, John W.

2010-01-01

Electric potential variations on the International Space Station (ISS) structure in low Earth orbit are dominated by contributions from interactions of the United States (US) 160 volt solar arrays with the relatively high density, low temperature plasma environment and inductive potentials generated by motion of the large vehicle across the Earth?s magnetic field. The Floating Potential Measurement Unit (FPMU) instrument suite comprising two Langmuir probes, a plasma impedance probe, and a floating potential probe was deployed in August 2006 for use in characterizing variations in ISS potential, the state of the ionosphere along the ISS orbit and its effect on ISS charging, evaluating effects of payloads and visiting vehicles, and for supporting ISS plasma hazard assessments. This presentation summarizes observations of ISS frame potential variations obtained from the FPMU from deployment in 2006 through the current time. We first describe ISS potential variations due to current collection by solar arrays in the day time sector of the orbit including eclipse exit and entry charging events, potential variations due to plasma environment variations in the equatorial anomaly, and visiting vehicles docked to the ISS structure. Next, we discuss potential variations due to inductive electric fields generated by motion of the vehicle across the geomagnetic field and the effects of external electric fields in the ionosphere. Examples of night time potential variations at high latitudes and their possible relationship to auroral charging are described and, finally, we demonstrate effects on the ISS potential due to European Space Agency and US plasma contactor devices.

Effects of Surfactant Contamination on the Next Generation Gas Trap for the ISS Internal Thermal Control System

NASA Technical Reports Server (NTRS)

Leimkuehler, Thomas O.; Lukens, Clark; Reeves, Daniel R.; Holt, James M.

2004-01-01

The current dual-membrane gas trap is designed to remove non-condensed gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Previous testing has shown that a hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal in clean deionized water. This paper presents results of testing to evaluate the effects of surfactant contamination on the steady-state performance of the hydrophobic-only design.

An alternative pluripotent state confers interspecies chimaeric competency

PubMed Central

Wu, Jun; Okamura, Daiji; Li, Mo; Suzuki, Keiichiro; Luo, Chongyuan; Ma, Li; He, Yupeng; Li, Zhongwei; Benner, Chris; Tamura, Isao; Krause, Marie N.; Nery, Joseph R.; Du, Tingting; Zhang, Zhuzhu; Hishida, Tomoaki; Takahashi, Yuta; Aizawa, Emi; Kim, Na Young; Lajara, Jeronimo; Guillen, Pedro; Campistol, Josep M.; Esteban, Concepcion Rodriguez; Ross, Pablo J.; Saghatelian, Alan; Ren, Bing; Ecker, Joseph R.; Belmonte, Juan Carlos Izpisua

2017-01-01

Pluripotency, the ability to generate any cell type of the body, is an evanescent attribute of embryonic cells. Transitory pluripotent cells can be captured at different time points during embryogenesis and maintained as embryonic stem cells or epiblast stem cells in culture. Since ontogenesis is a dynamic process in both space and time, it seems counterintuitive that these two temporal states represent the full spectrum of organismal pluripotency. Here we show that by modulating culture parameters, a stem-cell type with unique spatial characteristics and distinct molecular and functional features, designated as region-selective pluripotent stem cells (rsPSCs), can be efficiently obtained from mouse embryos and primate pluripotent stem cells, including humans. The ease of culturing and editing the genome of human rsPSCs offers advantages for regenerative medicine applications. The unique ability of human rsPSCs to generate post-implantation interspecies chimaeric embryos may facilitate our understanding of early human development and evolution. PMID:25945737

Advanced Space Fission Propulsion Systems

NASA Technical Reports Server (NTRS)

Houts, Michael G.; Borowski, Stanley K.

2010-01-01

Fission has been considered for in-space propulsion since the 1940s. Nuclear Thermal Propulsion (NTP) systems underwent extensive development from 1955-1973, completing 20 full power ground tests and achieving specific impulses nearly twice that of the best chemical propulsion systems. Space fission power systems (which may eventually enable Nuclear Electric Propulsion) have been flown in space by both the United States and the Former Soviet Union. Fission is the most developed and understood of the nuclear propulsion options (e.g. fission, fusion, antimatter, etc.), and fission has enjoyed tremendous terrestrial success for nearly 7 decades. Current space nuclear research and technology efforts are focused on devising and developing first generation systems that are safe, reliable and affordable. For propulsion, the focus is on nuclear thermal rockets that build on technologies and systems developed and tested under the Rover/NERVA and related programs from the Apollo era. NTP Affordability is achieved through use of previously developed fuels and materials, modern analytical techniques and test strategies, and development of a small engine for ground and flight technology demonstration. Initial NTP systems will be capable of achieving an Isp of 900 s at a relatively high thrust-to-weight ratio. The development and use of first generation space fission power and propulsion systems will provide new, game changing capabilities for NASA. In addition, development and use of these systems will provide the foundation for developing extremely advanced power and propulsion systems capable of routinely and affordably accessing any point in the solar system. The energy density of fissile fuel (8 x 10(exp 13) Joules/kg) is more than adequate for enabling extensive exploration and utilization of the solar system. For space fission propulsion systems, the key is converting the virtually unlimited energy of fission into thrust at the desired specific impulse and thrust-to-weight ratio. This presentation will discuss potential space fission propulsion options ranging from first generation systems to highly advanced systems. Ongoing research that shows promise for enabling second generation NTP systems with Isp greater than 1000 s will be discussed, as will the potential for liquid, gas, or plasma core systems. Space fission propulsion systems could also be used in conjunction with simple (water-based) propellant depots to enable routine, affordable missions to various destinations (e.g. moon, Mars, asteroids) once in-space infrastructure is sufficiently developed. As fuel and material technologies advance, very high performance Nuclear Electric Propulsion (NEP) systems may also become viable. These systems could enable sophisticated science missions, highly efficient cargo delivery, and human missions to numerous destinations. Commonalities between NTP, fission power systems, and NEP will be discussed.

Algorithms for Performance, Dependability, and Performability Evaluation using Stochastic Activity Networks

NASA Technical Reports Server (NTRS)

Deavours, Daniel D.; Qureshi, M. Akber; Sanders, William H.

1997-01-01

Modeling tools and technologies are important for aerospace development. At the University of Illinois, we have worked on advancing the state of the art in modeling by Markov reward models in two important areas: reducing the memory necessary to numerically solve systems represented as stochastic activity networks and other stochastic Petri net extensions while still obtaining solutions in a reasonable amount of time, and finding numerically stable and memory-efficient methods to solve for the reward accumulated during a finite mission time. A long standing problem when modeling with high level formalisms such as stochastic activity networks is the so-called state space explosion, where the number of states increases exponentially with size of the high level model. Thus, the corresponding Markov model becomes prohibitively large and solution is constrained by the the size of primary memory. To reduce the memory necessary to numerically solve complex systems, we propose new methods that can tolerate such large state spaces that do not require any special structure in the model (as many other techniques do). First, we develop methods that generate row and columns of the state transition-rate-matrix on-the-fly, eliminating the need to explicitly store the matrix at all. Next, we introduce a new iterative solution method, called modified adaptive Gauss-Seidel, that exhibits locality in its use of data from the state transition-rate-matrix, permitting us to cache portions of the matrix and hence reduce the solution time. Finally, we develop a new memory and computationally efficient technique for Gauss-Seidel based solvers that avoids the need for generating rows of A in order to solve Ax = b. This is a significant performance improvement for on-the-fly methods as well as other recent solution techniques based on Kronecker operators. Taken together, these new results show that one can solve very large models without any special structure.

Representations of the language recognition problem for a theorem prover

NASA Technical Reports Server (NTRS)

Minker, J.; Vanderbrug, G. J.

1972-01-01

Two representations of the language recognition problem for a theorem prover in first order logic are presented and contrasted. One of the representations is based on the familiar method of generating sentential forms of the language, and the other is based on the Cocke parsing algorithm. An augmented theorem prover is described which permits recognition of recursive languages. The state-transformation method developed by Cordell Green to construct problem solutions in resolution-based systems can be used to obtain the parse tree. In particular, the end-order traversal of the parse tree is derived in one of the representations. An inference system, termed the cycle inference system, is defined which makes it possible for the theorem prover to model the method on which the representation is based. The general applicability of the cycle inference system to state space problems is discussed. Given an unsatisfiable set S, where each clause has at most one positive literal, it is shown that there exists an input proof. The clauses for the two representations satisfy these conditions, as do many state space problems.

Continuous-variable entanglement distillation of non-Gaussian mixed states

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

Dong Ruifang; Lassen, Mikael; Department of Physics, Technical University of Denmark, Building 309, DK-2800 Lyngby

2010-07-15

Many different quantum-information communication protocols such as teleportation, dense coding, and entanglement-based quantum key distribution are based on the faithful transmission of entanglement between distant location in an optical network. The distribution of entanglement in such a network is, however, hampered by loss and noise that is inherent in all practical quantum channels. Thus, to enable faithful transmission one must resort to the protocol of entanglement distillation. In this paper we present a detailed theoretical analysis and an experimental realization of continuous variable entanglement distillation in a channel that is inflicted by different kinds of non-Gaussian noise. The continuous variablemore » entangled states are generated by exploiting the third order nonlinearity in optical fibers, and the states are sent through a free-space laboratory channel in which the losses are altered to simulate a free-space atmospheric channel with varying losses. We use linear optical components, homodyne measurements, and classical communication to distill the entanglement, and we find that by using this method the entanglement can be probabilistically increased for some specific non-Gaussian noise channels.« less

Dynamics of sleep/wake determination--Normal and abnormal

NASA Astrophysics Data System (ADS)

Mahowald, Mark W.; Schenck, Carlos H.; O'Connor, Kevin A.

1991-10-01

Virtually all members of the animal kingdom experience a relentless and powerful cycling of states of being: wakefulness, rapid eye movement sleep, and nonrapid eye movement sleep. Each of these states is composed of a number of physiologic variables generated in a variety of neural structures. The predictable oscillations of these states are driven by presumed neural pacemakers which are entrained to the 24 h geophysical environment by the light/dark cycle. Experiments in nature have indicated that wake/sleep rhythm perturbations may occur either involving desynchronization of the basic 24 h wake/sleep cycle within the geophysical 24 h cycle (circadian rhythm disturbances) or involving the rapid oscillation or incomplete declaration of state (such as narcolepsy). The use of phase spaces to describe states of being may be of interest in the description of state determination in both illness and health. Some fascinating clinical and experimental phenomena may represent bifurcations in the sleep/wake control system.

Genetic Algorithm-Guided, Adaptive Model Order Reduction of Flexible Aircrafts

NASA Technical Reports Server (NTRS)

Zhu, Jin; Wang, Yi; Pant, Kapil; Suh, Peter; Brenner, Martin J.

2017-01-01

This paper presents a methodology for automated model order reduction (MOR) of flexible aircrafts to construct linear parameter-varying (LPV) reduced order models (ROM) for aeroservoelasticity (ASE) analysis and control synthesis in broad flight parameter space. The novelty includes utilization of genetic algorithms (GAs) to automatically determine the states for reduction while minimizing the trial-and-error process and heuristics requirement to perform MOR; balanced truncation for unstable systems to achieve locally optimal realization of the full model; congruence transformation for "weak" fulfillment of state consistency across the entire flight parameter space; and ROM interpolation based on adaptive grid refinement to generate a globally functional LPV ASE ROM. The methodology is applied to the X-56A MUTT model currently being tested at NASA/AFRC for flutter suppression and gust load alleviation. Our studies indicate that X-56A ROM with less than one-seventh the number of states relative to the original model is able to accurately predict system response among all input-output channels for pitch, roll, and ASE control at various flight conditions. The GA-guided approach exceeds manual and empirical state selection in terms of efficiency and accuracy. The adaptive refinement allows selective addition of the grid points in the parameter space where flight dynamics varies dramatically to enhance interpolation accuracy without over-burdening controller synthesis and onboard memory efforts downstream. The present MOR framework can be used by control engineers for robust ASE controller synthesis and novel vehicle design.

Supersymmetric symplectic quantum mechanics

NASA Astrophysics Data System (ADS)

de Menezes, Miralvo B.; Fernandes, M. C. B.; Martins, Maria das Graças R.; Santana, A. E.; Vianna, J. D. M.

2018-02-01

Symplectic Quantum Mechanics SQM considers a non-commutative algebra of functions on a phase space Γ and an associated Hilbert space HΓ to construct a unitary representation for the Galilei group. From this unitary representation the Schrödinger equation is rewritten in phase space variables and the Wigner function can be derived without the use of the Liouville-von Neumann equation. In this article we extend the methods of supersymmetric quantum mechanics SUSYQM to SQM. With the purpose of applications in quantum systems, the factorization method of the quantum mechanical formalism is then set within supersymmetric SQM. A hierarchy of simpler hamiltonians is generated leading to new computation tools for solving the eigenvalue problem in SQM. We illustrate the results by computing the states and spectra of the problem of a charged particle in a homogeneous magnetic field as well as the corresponding Wigner function.

The Nosé–Hoover looped chain thermostat for low temperature thawed Gaussian wave-packet dynamics

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

Coughtrie, David J.; Tew, David P.

2014-05-21

We have used a generalised coherent state resolution of the identity to map the quantum canonical statistical average for a general system onto a phase-space average over the centre and width parameters of a thawed Gaussian wave packet. We also propose an artificial phase-space density that has the same behaviour as the canonical phase-space density in the low-temperature limit, and have constructed a novel Nosé–Hoover looped chain thermostat that generates this density in conjunction with variational thawed Gaussian wave-packet dynamics. This forms a new platform for evaluating statistical properties of quantum condensed-phase systems that has an explicit connection to themore » time-dependent Schrödinger equation, whilst retaining many of the appealing features of path-integral molecular dynamics.« less

Advanced heat receiver conceptual design study

NASA Technical Reports Server (NTRS)

Kesseli, James; Saunders, Roger; Batchelder, Gary

1988-01-01

Solar Dynamic space power systems are candidate electrical power generating systems for future NASA missions. One of the key components of the solar dynamic power system is the solar receiver/thermal energy storage (TES) subsystem. Receiver development was conducted by NASA in the late 1960's and since then a very limited amount of work has been done in this area. Consequently the state of the art (SOA) receivers designed for the IOC space station are large and massive. The objective of the Advanced Heat Receiver Conceptual Design Study is to conceive and analyze advanced high temperature solar dynamic Brayton and Stirling receivers. The goal is to generate innovative receiver concepts that are half of the mass, smaller, and more efficient than the SOA. It is also necessary that these innovative receivers offer ease of manufacturing, less structural complexity and fewer thermal stress problems. Advanced Brayton and Stirling receiver storage units are proposed and analyzed in this study which can potentially meet these goals.

Motif-Based Text Mining of Microbial Metagenome Redundancy Profiling Data for Disease Classification.

PubMed

Wang, Yin; Li, Rudong; Zhou, Yuhua; Ling, Zongxin; Guo, Xiaokui; Xie, Lu; Liu, Lei

2016-01-01

Text data of 16S rRNA are informative for classifications of microbiota-associated diseases. However, the raw text data need to be systematically processed so that features for classification can be defined/extracted; moreover, the high-dimension feature spaces generated by the text data also pose an additional difficulty. Here we present a Phylogenetic Tree-Based Motif Finding algorithm (PMF) to analyze 16S rRNA text data. By integrating phylogenetic rules and other statistical indexes for classification, we can effectively reduce the dimension of the large feature spaces generated by the text datasets. Using the retrieved motifs in combination with common classification methods, we can discriminate different samples of both pneumonia and dental caries better than other existing methods. We extend the phylogenetic approaches to perform supervised learning on microbiota text data to discriminate the pathological states for pneumonia and dental caries. The results have shown that PMF may enhance the efficiency and reliability in analyzing high-dimension text data.

A common-aperture X- and S-band four-function feedcone. [hornfeed design for antennas of Deep Space Network

NASA Technical Reports Server (NTRS)

Withington, J. R.; Williams, W. F.

1982-01-01

Williams and Withington (1979) have considered a prototype X-S-band feedhorn which enabled simultaneous X- and S-band reception from a Cassegrain antenna. This feedhorn has quite successfully demonstrated an alternate method to the standard Deep Space Network (DSN) system of multiple subreflectors and dichroic plate for dual-band reception. In connection with a Network Consolidation Program, involving centralized control of existing antennas and construction of new reflector antennas, a second-generation feedhorn/combiner was conceived to show that this common-aperture feedhorn system was capable of performing all necessary functions the DSN would be called upon to perform with existing and future X-S-band spacecraft. Attention is given to the feedhorn concept, the combiner concept, the first and the second generation of the horn, Sand X-band tuning, and planned capabilities. The feedhorn greatly extends the state of the art in DSN performance and will enhance DSN capabilities in the future.

Hybrid Power Management Program Evaluated Ultracapacitors for the Next Generation Launch Transportation Project

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.

2005-01-01

The NASA Glenn Research Center initiated baseline testing of ultracapacitors to obtain empirical data in determining the feasibility of using ultracapacitors for the Next Generation Launch Transportation (NGLT) Project. There are large transient loads associated with NGLT that require a very large primary energy source or an energy storage system. The primary power source used for this test was a proton-exchange-membrane (PEM) fuel cell. The energy storage system can consist of batteries, flywheels, or ultracapacitors. Ultracapacitors were used for these tests. NASA Glenn has a wealth of experience in ultracapacitor technology through the Hybrid Power Management (HPM) Program, which the Avionics, Power and Communications Branch of Glenn s Engineering Development Division initiated for the Technology Transfer and Partnership Office. HPM is the innovative integration of diverse, state-ofthe- art power devices in optimal configurations for space and terrestrial applications. The appropriate application and control of the various advanced power devices (such as ultracapacitors and fuel cells) significantly improves overall system performance and efficiency. HPM has extremely wide potential. Applications include power generation, transportation systems, biotechnology systems, and space power systems. HPM has the potential to significantly alleviate global energy concerns, improve the environment, and stimulate the economy.

Lightweight Innovative Solar Array (LISA): Providing Higher Power to Small Spacecraft

NASA Technical Reports Server (NTRS)

Johnson, Les; Carr, John; Fabisinski, Leo; Russell,Tiffany; Smith, Leigh

2015-01-01

Affordable and convenient access to electrical power is essential for all spacecraft and is a critical design driver for the next generation of smallsats, including cubesats, which are currently extremely power limited. The Lightweight Innovative Solar Array (LISA), a concept designed, prototyped, and tested at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama provides an affordable, lightweight, scalable, and easily manufactured approach for power generation in space. This flexible technology has many wide-ranging applications from serving small satellites to providing abundant power to large spacecraft in GEO and beyond. By using very thin, ultra-flexible solar arrays adhered to an inflatable structure, a large area (and thus large amount of power) can be folded and packaged into a relatively small volume. The LISA array comprises a launch-stowed, orbit-deployed structure on which lightweight photovoltaic devices and, potentially, transceiver elements are embedded. The system will provide a 2.5 to 5 fold increase in specific power generation (Watts/kilogram) coupled with a >2x enhancement of stowed volume (Watts/cubic-meter) and a decrease in cost (dollars/Watt) when compared to state-of-the-art solar arrays.

Equilibrium Molecular Thermodynamics from Kirkwood Sampling

PubMed Central

2015-01-01

We present two methods for barrierless equilibrium sampling of molecular systems based on the recently proposed Kirkwood method (J. Chem. Phys.2009, 130, 134102). Kirkwood sampling employs low-order correlations among internal coordinates of a molecule for random (or non-Markovian) sampling of the high dimensional conformational space. This is a geometrical sampling method independent of the potential energy surface. The first method is a variant of biased Monte Carlo, where Kirkwood sampling is used for generating trial Monte Carlo moves. Using this method, equilibrium distributions corresponding to different temperatures and potential energy functions can be generated from a given set of low-order correlations. Since Kirkwood samples are generated independently, this method is ideally suited for massively parallel distributed computing. The second approach is a variant of reservoir replica exchange, where Kirkwood sampling is used to construct a reservoir of conformations, which exchanges conformations with the replicas performing equilibrium sampling corresponding to different thermodynamic states. Coupling with the Kirkwood reservoir enhances sampling by facilitating global jumps in the conformational space. The efficiency of both methods depends on the overlap of the Kirkwood distribution with the target equilibrium distribution. We present proof-of-concept results for a model nine-atom linear molecule and alanine dipeptide. PMID:25915525

The birth of a quasiparticle in silicon observed in time-frequency space.

PubMed

Hase, Muneaki; Kitajima, Masahiro; Constantinescu, Anca Monia; Petek, Hrvoje

2003-11-06

The concept of quasiparticles in solid-state physics is an extremely powerful tool for describing complex many-body phenomena in terms of single-particle excitations. Introducing a simple particle, such as an electron, hole or phonon, deforms a many-body system through its interactions with other particles. In this way, the added particle is 'dressed' or 'renormalized' by a self-energy cloud that describes the response of the many-body system, so forming a new entity--the quasiparticle. Using ultrafast laser techniques, it is possible to impulsively generate bare particles and observe their subsequent dressing by the many-body interactions (that is, quasiparticle formation) on the time and energy scales governed by the Heisenberg uncertainty principle. Here we describe the coherent response of silicon to excitation with a 10-femtosecond (10(-14) s) laser pulse. The optical pulse interacts with the sample by way of the complex second-order nonlinear susceptibility to generate a force on the lattice driving coherent phonon excitation. Transforming the transient reflectivity signal into frequency-time space reveals interference effects leading to the coherent phonon generation and subsequent dressing of the phonon by electron-hole pair excitations.

Proximity Operations and Docking Sensor Development

NASA Technical Reports Server (NTRS)

Howard, Richard T.; Bryan, Thomas C.; Brewster, Linda L.; Lee, James E.

2009-01-01

The Next Generation Advanced Video Guidance Sensor (NGAVGS) has been under development for the last three years as a long-range proximity operations and docking sensor for use in an Automated Rendezvous and Docking (AR&D) system. The first autonomous rendezvous and docking in the history of the U.S. Space Program was successfully accomplished by Orbital Express, using the Advanced Video Guidance Sensor (AVGS) as the primary docking sensor. That flight proved that the United States now has a mature and flight proven sensor technology for supporting Crew Exploration Vehicles (CEV) and Commercial Orbital Transport Systems (COTS) Automated Rendezvous and Docking (AR&D). NASA video sensors have worked well in the past: the AVGS used on the Demonstration of Autonomous Rendezvous Technology (DART) mission operated successfully in spot mode out to 2 km, and the first generation rendezvous and docking sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on Space Shuttle flights in 1997 and 1998. 12 Parts obsolescence issues prevent the construction of more AVGS units, and the next generation sensor was updated to allow it to support the CEV and COTS programs. The flight proven AR&D sensor has been redesigned to update parts and add additional capabilities for CEV and COTS with the development of the Next Generation AVGS at the Marshall Space Flight Center. The obsolete imager and processor are being replaced with new radiation tolerant parts. In addition, new capabilities include greater sensor range, auto ranging capability, and real-time video output. This paper presents some sensor hardware trades, use of highly integrated laser components, and addresses the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS) and other Constellation vehicles. It also discusses approaches for upgrading AVGS to address parts obsolescence, and concepts for minimizing the sensor footprint, weight, and power requirements. In addition, the testing of the brassboard and proto-type NGAVGS units will be discussed along with the use of the NGAVGS as a proximity operations and docking sensor.

Thermophotovoltaic power conversion systems: Current performance and future potential

DOE PAGES

Celanovic, Ivan; Bermel, Peter; Soljacic, Marin

2011-01-01

Thermophotovoltaic (TPV) systems offer a unique, solid-state approach to converting heat into electricity based on thermal radiation. TPV is particularly suitable for certain classes of power generation applications that are not well served by standard engines, such as long, remote missions where repairs are difficult, and portable generation where space and weight are at a premium. While standard thermophotovoltaics are limited in their conversion efficiency, photonic crystals can improve performance by an order of magnitude for a number of systems. While there are many potential applications, two exemplary systems are discussed: TPV μreactors for portable power generation in a mm-scalemore » form factor, and solar TPV for long-term off-grid power generation from sunlight. In both cases, photonic crystals can enable potential performance exceeding that of many other well-known technologies, such as single-junction photovoltaics.« less

Accelerated computer generated holography using sparse bases in the STFT domain.

PubMed

Blinder, David; Schelkens, Peter

2018-01-22

Computer-generated holography at high resolutions is a computationally intensive task. Efficient algorithms are needed to generate holograms at acceptable speeds, especially for real-time and interactive applications such as holographic displays. We propose a novel technique to generate holograms using a sparse basis representation in the short-time Fourier space combined with a wavefront-recording plane placed in the middle of the 3D object. By computing the point spread functions in the transform domain, we update only a small subset of the precomputed largest-magnitude coefficients to significantly accelerate the algorithm over conventional look-up table methods. We implement the algorithm on a GPU, and report a speedup factor of over 30. We show that this transform is superior over wavelet-based approaches, and show quantitative and qualitative improvements over the state-of-the-art WASABI method; we report accuracy gains of 2dB PSNR, as well improved view preservation.

Annual-ring-type quasi-phase-matching crystal for generation of narrowband high-dimensional entanglement

NASA Astrophysics Data System (ADS)

Hua, Yi-Lin; Zhou, Zong-Quan; Liu, Xiao; Yang, Tian-Shu; Li, Zong-Feng; Li, Pei-Yun; Chen, Geng; Xu, Xiao-Ye; Tang, Jian-Shun; Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can

2018-01-01

A photon pair can be entangled in many degrees of freedom such as polarization, time bins, and orbital angular momentum (OAM). Among them, the OAM of photons can be entangled in an infinite-dimensional Hilbert space which enhances the channel capacity of sharing information in a network. Twisted photons generated by spontaneous parametric down-conversion offer an opportunity to create this high-dimensional entanglement, but a photon pair generated by this process is typically wideband, which makes it difficult to interface with the quantum memories in a network. Here we propose an annual-ring-type quasi-phase-matching (QPM) crystal for generation of the narrowband high-dimensional entanglement. The structure of the QPM crystal is designed by tracking the geometric divergences of the OAM modes that comprise the entangled state. The dimensionality and the quality of the entanglement can be greatly enhanced with the annual-ring-type QPM crystal.

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

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

Krishnan, Venkat; Das, Trishna

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

Use of CCSDS Packets Over SpaceWire to Control Hardware

NASA Technical Reports Server (NTRS)

Haddad, Omar; Blau, Michael; Haghani, Noosha; Yuknis, William; Albaijes, Dennis

2012-01-01

For the Lunar Reconnaissance Orbiter, the Command and Data Handling subsystem consisted of several electronic hardware assemblies that were connected with SpaceWire serial links. Electronic hardware would be commanded/controlled and telemetry data was obtained using the SpaceWire links. Prior art focused on parallel data buses and other types of serial buses, which were not compatible with the SpaceWire and the core flight executive (CFE) software bus. This innovation applies to anything that utilizes both SpaceWire networks and the CFE software. The CCSDS (Consultative Committee for Space Data Systems) packet contains predetermined values in its payload fields that electronic hardware attached at the terminus of the SpaceWire node would decode, interpret, and execute. The hardware s interpretation of the packet data would enable the hardware to change its state/configuration (command) or generate status (telemetry). The primary purpose is to provide an interface that is compatible with the hardware and the CFE software bus. By specifying the format of the CCSDS packet, it is possible to specify how the resulting hardware is to be built (in terms of digital logic) that results in a hardware design that can be controlled by the CFE software bus in the final application

Overview study of Space Power Technologies for the advanced energetics program. [spacecraft

NASA Technical Reports Server (NTRS)

Taussig, R.; Gross, S.; Millner, A.; Neugebauer, M.; Phillips, W.; Powell, J.; Schmidt, E.; Wolf, M.; Woodcock, G.

1981-01-01

Space power technologies are reviewed to determine the state-of-the-art and to identify advanced or novel concepts which promise large increases in performance. The potential for incresed performance is judged relative to benchmarks based on technologies which have been flight tested. Space power technology concepts selected for their potentially high performance are prioritized in a list of R & D topical recommendations for the NASA program on Advanced Energetics. The technology categories studied are solar collection, nuclear power sources, energy conversion, energy storage, power transmission, and power processing. The emphasis is on electric power generation in space for satellite on board electric power, for electric propulsion, or for beamed power to spacecraft. Generic mission categories such as low Earth orbit missions and geosynchronous orbit missions are used to distinguish general requirements placed on the performance of power conversion technology. Each space power technology is judged on its own merits without reference to specific missions or power systems. Recommendations include 31 space power concepts which span the entire collection of technology categories studied and represent the critical technologies needed for higher power, lighter weight, more efficient power conversion in space.

TMS delivered for A-3 Test Stand

NASA Image and Video Library

2010-03-17

A state-of-the-art thrust measurement system for the A-3 Test Stand under construction at NASA's John C. Stennis Space Center was delivered March 17. Once completed, the A-3 stand (seen in background) will allow simulated high-altitude testing on the next generation of rocket engines for America's space program. Work on the stand began in 2007, with activation scheduled for 2012. The stand is the first major test structure to be built at Stennis since the 1960s. The recently delivered TMS was fabricated by Thrust Measurement Systems in Illinois. It is an advanced calibration system capable of measuring vertical and horizontal thrust loads with an accuracy within 0.15 percent at 225,000 pounds.

Langley aerospace test highlights - 1986

NASA Technical Reports Server (NTRS)

1987-01-01

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. This report highlights some of the significant tests which were performed during calendar year 1986 in Langley test facilities, a number of which are unique in the world. The report illustrates both the broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research.

OAST Space Theme Workshop. Volume 3: Working Group Summary. 5: Propulsion (P-1). A. Summary Statement. B. Technology Needs (Form 1). C. Priority Assessments (Form 2)

NASA Technical Reports Server (NTRS)

1976-01-01

All themes require some form of advanced propulsion capabilities to achieve their stated objectives. Requirements cover a broad spectrum ranging from a new generation of heavy lift launch vehicles to low thrust, long lift system for on-orbit operations. The commonality extant between propulsive technologies was established and group technologies were grouped into vehicle classes by functional capability. The five classes of launch vehicles identified by the space transportation theme were augmented with a sixth class, encompassing planetary and on-orbit operations. Propulsion technologies in each class were then ranked, and assigned priority numbers. Prioritized technologies were matched to theme requirements.

Digital Beamforming Synthetic Aperture Radar Developments at NASA Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Rincon, Rafael; Fatoyinbo, Temilola; Osmanoglu, Batuhan; Lee, Seung Kuk; Du Toit, Cornelis F.; Perrine, Martin; Ranson, K. Jon; Sun, Guoqing; Deshpande, Manohar; Beck, Jaclyn;

Universal linear and nonlinear electrodynamics of a Dirac fluid

NASA Astrophysics Data System (ADS)

Sun, Zhiyuan; Basov, Dmitry N.; Fogler, Michael M.

2018-03-01

A general relation is derived between the linear and second-order nonlinear ac conductivities of an electron system in the hydrodynamic regime of frequencies below the interparticle scattering rate. The magnitude and tensorial structure of the hydrodynamic nonlinear conductivity are shown to differ from their counterparts in the more familiar kinetic regime of higher frequencies. Due to universality of the hydrodynamic equations, the obtained formulas are valid for systems with an arbitrary Dirac-like dispersion, ranging from solid-state electron gases to free-space plasmas, either massive or massless, at any temperature, chemical potential, or space dimension. Predictions for photon drag and second-harmonic generation in graphene are presented as one application of this theory.

Revealing nonclassicality beyond Gaussian states via a single marginal distribution

PubMed Central

Park, Jiyong; Lu, Yao; Lee, Jaehak; Shen, Yangchao; Zhang, Kuan; Zhang, Shuaining; Zubairy, Muhammad Suhail; Kim, Kihwan; Nha, Hyunchul

2017-01-01

A standard method to obtain information on a quantum state is to measure marginal distributions along many different axes in phase space, which forms a basis of quantum-state tomography. We theoretically propose and experimentally demonstrate a general framework to manifest nonclassicality by observing a single marginal distribution only, which provides a unique insight into nonclassicality and a practical applicability to various quantum systems. Our approach maps the 1D marginal distribution into a factorized 2D distribution by multiplying the measured distribution or the vacuum-state distribution along an orthogonal axis. The resulting fictitious Wigner function becomes unphysical only for a nonclassical state; thus the negativity of the corresponding density operator provides evidence of nonclassicality. Furthermore, the negativity measured this way yields a lower bound for entanglement potential—a measure of entanglement generated using a nonclassical state with a beam-splitter setting that is a prototypical model to produce continuous-variable (CV) entangled states. Our approach detects both Gaussian and non-Gaussian nonclassical states in a reliable and efficient manner. Remarkably, it works regardless of measurement axis for all non-Gaussian states in finite-dimensional Fock space of any size, also extending to infinite-dimensional states of experimental relevance for CV quantum informatics. We experimentally illustrate the power of our criterion for motional states of a trapped ion, confirming their nonclassicality in a measurement-axis–independent manner. We also address an extension of our approach combined with phase-shift operations, which leads to a stronger test of nonclassicality, that is, detection of genuine non-Gaussianity under a CV measurement. PMID:28077456

Revealing nonclassicality beyond Gaussian states via a single marginal distribution.

PubMed

Park, Jiyong; Lu, Yao; Lee, Jaehak; Shen, Yangchao; Zhang, Kuan; Zhang, Shuaining; Zubairy, Muhammad Suhail; Kim, Kihwan; Nha, Hyunchul

2017-01-31

A standard method to obtain information on a quantum state is to measure marginal distributions along many different axes in phase space, which forms a basis of quantum-state tomography. We theoretically propose and experimentally demonstrate a general framework to manifest nonclassicality by observing a single marginal distribution only, which provides a unique insight into nonclassicality and a practical applicability to various quantum systems. Our approach maps the 1D marginal distribution into a factorized 2D distribution by multiplying the measured distribution or the vacuum-state distribution along an orthogonal axis. The resulting fictitious Wigner function becomes unphysical only for a nonclassical state; thus the negativity of the corresponding density operator provides evidence of nonclassicality. Furthermore, the negativity measured this way yields a lower bound for entanglement potential-a measure of entanglement generated using a nonclassical state with a beam-splitter setting that is a prototypical model to produce continuous-variable (CV) entangled states. Our approach detects both Gaussian and non-Gaussian nonclassical states in a reliable and efficient manner. Remarkably, it works regardless of measurement axis for all non-Gaussian states in finite-dimensional Fock space of any size, also extending to infinite-dimensional states of experimental relevance for CV quantum informatics. We experimentally illustrate the power of our criterion for motional states of a trapped ion, confirming their nonclassicality in a measurement-axis-independent manner. We also address an extension of our approach combined with phase-shift operations, which leads to a stronger test of nonclassicality, that is, detection of genuine non-Gaussianity under a CV measurement.

Analysis of the Impacts of the Clean Power Plan

EIA Publications

2015-01-01

This report responds to an August 2014 request to the U.S. Energy Information Administration (EIA) from Representative Lamar Smith, Chairman of the U.S. House of Representatives Committee on Science, Space, and Technology, for an analysis of the Environmental Protection Agency's (EPA) proposed Clean Power Plan under which states would be required to develop plans to reduce carbon dioxide (CO2) emissions rates from existing fossil-fired electricity generating units.

Modeling and Analysis of Power Processing Systems (MAPPS). Volume 2: Appendices

NASA Technical Reports Server (NTRS)

Lee, F. C.; Radman, S.; Carter, R. A.; Wu, C. H.; Yu, Y.; Chang, R.

1980-01-01

The computer programs and derivations generated in support of the modeling and design optimization program are presented. Programs for the buck regulator, boost regulator, and buck-boost regulator are described. The computer program for the design optimization calculations is presented. Constraints for the boost and buck-boost converter were derived. Derivations of state-space equations and transfer functions are presented. Computer lists for the converters are presented, and the input parameters justified.

Future Market Share of Space Solar Electric Power Under Open Competition

NASA Astrophysics Data System (ADS)

Smith, S. J.; Mahasenan, N.; Clarke, J. F.; Edmonds, J. A.

2002-01-01

This paper assesses the value of Space Solar Power deployed under market competition with a full suite of alternative energy technologies over the 21st century. Our approach is to analyze the future energy system under a number of different scenarios that span a wide range of possible future demographic, socio-economic, and technological developments. Scenarios both with, and without, carbon dioxide concentration stabilization policies are considered. We use the comprehensive set of scenarios created for the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (Nakicenovic and Swart 2000). The focus of our analysis will be the cost of electric generation. Cost is particularly important when considering electric generation since the type of generation is, from a practical point of view, largely irrelevant to the end-user. This means that different electricity generation technologies must compete on the basis of price. It is important to note, however, that even a technology that is more expensive than average can contribute to the overall generation mix due to geographical and economic heterogeneity (Clarke and Edmonds 1993). This type of competition is a central assumption of the modeling approach used here. Our analysis suggests that, under conditions of full competition of all available technologies, Space Solar Power at 7 cents per kW-hr could comprise 5-10% of global electric generation by the end of the century, with a global total generation of 10,000 TW-hr. The generation share of Space Solar Power is limited due to competition with lower-cost nuclear, biomass, and terrestrial solar PV and wind. The imposition of a carbon constraint does not significantly increase the total amount of power generated by Space Solar Power in cases where a full range of advanced electric generation technologies are also available. Potential constraints on the availability of these other electric generation options can increase the amount of electricity generated by Space Solar Power. In agreement with previous work on this subject, we note that launch costs are a significant impediment for the widespread implementation of Space Solar Power. KEY WORDS: space satellite power, advanced electric generation, electricity price, climate change

Overview of the Environmental Control and Life Support System (ECLSS) Testing At MSFC

NASA Technical Reports Server (NTRS)

Traweek, Mary S.; Tatara, James D.

1998-01-01

Previously, almost all water used by the crew during space flight has been transported from earth or generated in-flight as a by-product of fuel cells. Additionally, this water has been stored and used for relatively short periods. To achieve the United States' commitment to a permanent manned presence in space, more innovative techniques are demanded. Over 20,000 pounds of water and large quantities of air would have to be transported to the International Space Station (ISS) every 90 days with a corresponding amount of waste returned to earth, for an 8-person crew. This approach results in prohibitive logistics costs, and necessitates near complete recovery and recycling of water. The potential hazards associated with long-term reuse of reclaimed water and revitalized air resulted in the recognition that additional characterization of closed-loop systems and products is essential. Integrated physical/chemical systems have been designed, assembled, and operated to provide air and potable water meeting ISS quality specifications. The purpose of the Environmental Control and Life Support System (ECLSS) test program at NASA's Marshall Space Flight Center is to conduct research related to the performance of the ISS and its Environmental Control components. The ECLSS Test Program encompasses the Water Recovery Test (WRT), the Integrated Air Revitalization Test (IART), and Life Testing, which permits ECLSS design evaluation. These subsystems revitalize air and reclaim waste waters representative of those to be generated on-orbit. This paper provides an overview of MSFC's 1997 ECLSS testing. Specific tests include: the Stage 10 Water Recovery Test; the Contaminant Injection Test; the Performance Enhancement Test and Life Testing of the Four Bed Molecular Sieve; the Oxygen Generator Assembly Life Test; and the ISS Water Distribution Biofilm Life Test.

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

Chen, Li-Jen

The project has accomplished the following achievements including the goals outlined in the original proposal. Generation and measurements of Debye-scale electron holes in laboratory: We have generated by beam injections electron solitary waves in the LAPD experiments. The measurements were made possible by the fabrication of the state-of-the-art microprobes at UCLA to measure Debye-scale electric fields [Chiang et al., 2011]. We obtained a result that challenged the state of knowledge about electron hole generation. We found that the electron holes were not due to two-stream instability, but generated by a current-driven instability that also generated whistler-mode waves [Lefebvre et al.,more » 2011, 2010b]. Most of the grant supported a young research scientist Bertrand Lefebvre who led the dissemination of the laboratory experimental results. In addition to two publications, our work relevant to the laboratory experiments on electron holes has resulted in 7 invited talks [Chen, 2007, 2009; Pickett et al., 2009a; Lefebvre et al., 2010a; Pickett et al., 2010; Chen et al., 2011c, b] (including those given by the co-I Jolene Pickett) and 2 contributed talks [Lefebvre et al., 2009b, a]. Discovery of elecctron phase-space-hole structure in the reconnection electron layer: Our theoretical analyses and simulations under this project led to the discovery of an inversion electric field layer whose phase-space signature is an electron hole within the electron diffusion layer in 2D anti-parallel reconnection [Chen et al., 2011a]. We carried out particle tracing studies to understand the electron orbits that result in the phase-space hole structure. Most importantly, we showed that the current density in the electron layer is limited in collisionless reconnection with negligible guide field by the cyclotron turning of meandering electrons. Comparison of electrostatic solitary waves in current layers observed by Cluster and in LAPD: We compared the ESWs observed in a supersubstorm by the Cluster spacecraft and those measured in LAPD. One of the similarities in the characteristics of ESWs observed in space and in LAPD is that the time duration tends to be approximately the inverse of the electron plasma frequency [Pickett et al., 2009b]. Discovery of suprathermal electron bursts inside a series of magnetic islands: Our effort in examining the roles of ESWs in reconnection current layers resulted in the serendipitous discovery that was published in Nature Physics. In earth’s magnetosphere, we observed through the measurements from the four Cluster spacecraft, a series of magnetic islands and suprathermal electron bursts within the islands. The islands were identified to be effectively acceleration sites for electrons [Chen et al., 2008, 2009].« less

Tokamak with in situ magnetohydrodynamic generation of toroidal magnetic field

DOEpatents

Schaffer, Michael J.

1986-01-01

A tokamak apparatus includes an electrically conductive metal pressure vessel for defining a chamber and confining liquid therein. A liner disposed within said chamber defines a toroidal space within the liner and confines gas therein. The metal vessel provides an electrically conductive path linking the toroidal space. Liquid metal is forced outwardly through the chamber outside of the toroidal space to generate electric current in the conductive path and thereby generate a toroidal magnetic field within the toroidal space. Toroidal plasma is developed within the toroidal space about the major axis thereof.

Coherent Frequency Reference System for the NASA Deep Space Network

NASA Technical Reports Server (NTRS)

Tucker, Blake C.; Lauf, John E.; Hamell, Robert L.; Gonzaler, Jorge, Jr.; Diener, William A.; Tjoelker, Robert L.

2010-01-01

The NASA Deep Space Network (DSN) requires state-of-the-art frequency references that are derived and distributed from very stable atomic frequency standards. A new Frequency Reference System (FRS) and Frequency Reference Distribution System (FRD) have been developed, which together replace the previous Coherent Reference Generator System (CRG). The FRS and FRD each provide new capabilities that significantly improve operability and reliability. The FRS allows for selection and switching between frequency standards, a flywheel capability (to avoid interruptions when switching frequency standards), and a frequency synthesis system (to generate standardized 5-, 10-, and 100-MHz reference signals). The FRS is powered by redundant, specially filtered, and sustainable power systems and includes a monitor and control capability for station operations to interact and control the frequency-standard selection process. The FRD receives the standardized 5-, 10-, and 100-MHz reference signals and distributes signals to distribution amplifiers in a fan out fashion to dozens of DSN users that require the highly stable reference signals. The FRD is also powered by redundant, specially filtered, and sustainable power systems. The new DSN Frequency Distribution System, which consists of the FRS and FRD systems described here, is central to all operational activities of the NASA DSN. The frequency generation and distribution system provides ultra-stable, coherent, and very low phase-noise references at 5, l0, and 100 MHz to between 60 and 100 separate users at each Deep Space Communications Complex.

The Formation of Solid Particles from their Gas-Phase Molecular Precursors in Cosmic Environments with NASA Ames' COSmIC Facility

NASA Technical Reports Server (NTRS)

Salama, Farid

2014-01-01

We present and discuss the unique characteristics and capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory. COSmIC stands for Cosmic Simulation Chamber and is dedicated to the study of molecules and ions under the low temperature and high vacuum conditions that are required to simulate interstellar, circumstellar and planetary physical environments in space. COSmIC integrates a variety of state-of-the-art instruments that allow forming, processing and monitoring simulated space conditions for planetary, circumstellar and interstellar materials in the laboratory. COSmIC is composed of a Pulsed Discharge Nozzle (PDN) expansion that generates a free jet supersonic expansion coupled to two ultrahigh-sensitivity, complementary in situ diagnostics: a Cavity Ring Down Spectroscopy (CRDS) system for photonic detection and a Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent, unique, laboratory astrophysics results that were obtained using the capabilities of COSmIC will be discussed, in particular the progress that have been achieved in monitoring in the laboratory the formation of solid gains from their gas-phase molecular precursors in environments as varied as stellar/circumstellar outflow and planetary atmospheres. Plans for future, next generation, laboratory experiments on cosmic molecules and grains in the growing field of laboratory astrophysics will also be addressed as well as the implications of these studies for current and upcoming space missions.

In situ experimental study of carbon monoxide generation by gasoline-powered electric generator in an enclosed space.

PubMed

Wang, Liangzhu; Emmerich, Steven J; Persily, Andrew K

2010-12-01

On the basis of currently available data, approximately 97% of generator-related carbon monoxide (CO) fatalities are caused by operating currently marketed, carbureted spark-ignited gasoline-powered generators (not equipped with emission controls) in enclosed spaces. To better understand and to reduce the occurrence of these fatalities, research is needed to quantify CO generation rates, develop and test CO emission control devices, and evaluate CO transport and exposure when operating a generator in an enclosed space. As a first step in these efforts, this paper presents measured CO generation rates from a generator without any emission control devices operating in an enclosed space under real weather conditions. This study expands on previously published information from the U.S. Consumer Product Safety Commission. Thirteen separate tests were conducted under different weather conditions at half and full generator load settings. It was found that the CO level in the shed reached a maximum value of 29,300 +/- 580 mg/m3, whereas the oxygen (O2) was depleted to a minimum level of 16.2 +/- 0.02% by volume. For the test conditions of real weather and generator operation, the CO generation and the O2 consumption could be expressed as time-averaged generation/consumption rates. It was also found that the CO generation and O2 consumption rates can be correlated to the O2 levels in the space and the actual load output from the generator. These correlations are shown to agree well with the measurements.

An Experimental Investigation of Forced Mixing of a Turbulent Boundary Layer in an Annular Diffuser. Ph.D. Thesis - Ohio State Univ.; [for boundary layer control

NASA Technical Reports Server (NTRS)

Shaw, R. J.

1979-01-01

The forced mixing process of a turbulent boundary layer in an axisymmetric annular diffuser using conventional wing-like vortex generators was studied. Flow field measurements were made at four axial locations downstream of the vortex generators. At each axial location, a total of 25 equally spaced profiles were measured behind three consecutive vortex generators which formed two pairs of vortex generators. Hot film anemometry probes measured the boundary layer turbulence structure at the same locations where pressure measurements were made. Both single and cross film probes were used. The diffuser turbulence data was teken only for a nominal inlet Mach number of 0.3. Three vortex generator configurations were tested. The differences between configurations involved changes in size and relative vortex generator positions. All three vortex generator configurations tested provided increases in diffuser performance. Distinct differences in the boundary layer integral properties and skin friction levels were noted between configurations. The axial turbulence intensity and Reynolds stress profiles measured displayed similarities in trends but differences in levels for the three configurations.

The French Space Operation Act: Technical Regulations

NASA Astrophysics Data System (ADS)

Trinchero, J. P.; Lazare, B.

2010-09-01

The French Space Operation Act(FSOA) stipulates that a prime objective of the National technical regulations is to protect people, property, public health and the environment. Compliance with these technical regulations is mandatory as of 10 December 2010 for space operations by French space operators and for space operations from French territory. The space safety requirements and regulations governing procedures are based on national and international best practices and experience. A critical design review of the space system and procedures shall be carried out by the applicant, in order to verify compliance with the Technical Regulations. An independent technical assessment of the operation is delegated to CNES. The principles applied when drafting technical regulations are as follows: requirements must as far as possible establish the rules according to the objective to be obtained, rather than how it is to be achieved; requirements must give preference to international standards recognised as being the state of the art; requirements must take previous experience into account. Technical regulations are divided into three sections covering common requirements for the launch, control and return of a space object. A dedicated section will cover specific rules to be applied at the Guiana Space Centre. The main topics addressed by the technical regulations are: operator safety management system; study of risks to people, property, public health and the Earth’s environment; impact study on the outer space environment: space debris generated by the operation; planetary protection.

Advanced Space Transportation Program (ASTP)

NASA Image and Video Library

2002-10-01

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Space Launch Initiative (SLI), NASA's priority developmental program focused on empowering America's leadership in space. SLI includes commercial, higher education, and Defense partnerships and contracts to offer widespread participation in both the risk and success of developing our nation's next-generation reusable launch vehicle. This photo depicts an artist's concept of a future second-generation launch vehicle enroute to the International Space Station. For the SLI, architecture definition includes all components of the next-generation reusable launch system: Earth-to-orbit vehicles (the Space Shuttle is the first generation earth-to-orbit vehicle), crew transfer vehicles, transfer stages, ground processing systems, flight operations systems, and development of business case strategies. Three contractor teams have each been funded to develop potential second-generation reusable launch system architectures: The Boeing Company of Seal Beach, California; Lockheed Martin Corporation of Denver, Colorado along with a team including Northrop Grumman of El Segundo, California; and Orbital Sciences Corporation of Dulles, Virginia.

SLI Artist's Concept-Vehicle Enroute to Space Station

NASA Technical Reports Server (NTRS)

2002-01-01

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Space Launch Initiative (SLI), NASA's priority developmental program focused on empowering America's leadership in space. SLI includes commercial, higher education, and Defense partnerships and contracts to offer widespread participation in both the risk and success of developing our nation's next-generation reusable launch vehicle. This photo depicts an artist's concept of a future second-generation launch vehicle enroute to the International Space Station. For the SLI, architecture definition includes all components of the next-generation reusable launch system: Earth-to-orbit vehicles (the Space Shuttle is the first generation earth-to-orbit vehicle), crew transfer vehicles, transfer stages, ground processing systems, flight operations systems, and development of business case strategies. Three contractor teams have each been funded to develop potential second-generation reusable launch system architectures: The Boeing Company of Seal Beach, California; Lockheed Martin Corporation of Denver, Colorado along with a team including Northrop Grumman of El Segundo, California; and Orbital Sciences Corporation of Dulles, Virginia.

Flight and Integrated Testing: Blazing the Trail for the Ares Launch Vehicles

NASA Technical Reports Server (NTRS)

Taylor, James L.; Cockrell, Charlie; Robinson, Kimberly; Tuma, Margaret L.; Flynn, Kevin C.; Briscoe, Jeri M.

2007-01-01

It has been 30 years since the United States last designed and built a human-rated launch vehicle. The National Aeronautics and Space Administration (NASA) has marshaled unique resources from the government and private sectors that will carry the next generation of astronauts into space safer and more efficiently than ever and send them to the Moon to develop a permanent outpost. NASA's Flight and Integrated Test Office (FITO) located at Marshall Space Flight Center and the Ares I-X Mission Management Office have primary responsibility for developing and conducting critical ground and flight tests for the Ares I and Ares V launch vehicles. These tests will draw upon Saturn and the Space Shuttle experiences, which taught the value of using sound systems engineering practices, while also applying aerospace best practices such as "test as you fly" and other lessons learned. FITO will use a variety of methods to reduce the technical, schedule, and cost risks of flying humans safely aboard a launch vehicle.

Green Application for Space Power

NASA Technical Reports Server (NTRS)

Robinson, Joel

2015-01-01

Most space vehicle auxiliary power units (APUs) use hydrazine propellant for generating power. Hydrazine is a toxic, hazardous fuel that requires special safety equipment and processes for handling and loading. In recent years, there has been development of two green propellants (less toxic) that could enable their use in APUs. The Swedish government, in concert with the Swedish Space Corporation, has developed a propellant based on ammonium dinitramide (LMP-103S) that was flown on the Prisma spacecraft in 2010. The United States Air Force (USAF) has been developing a propellant based on hydroxylammonium nitrate (AFM315E) that is scheduled to fly on the Green Propellant Infusion Mission in the spring of 2016 to demonstrate apogee and reaction control thrusters. However, no one else in the Agency is currently pursuing use of green propellants for application to the APUs. Per the TA-01 Launch Propulsion Roadmap, the Space Technology Mission Directorate had identified the need to have a green propellant APU by 2015. This is our motivation for continuing activities.

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

Geiger, K.; Longacre, R.; Srivastava, D.K.

VNI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. It uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme, as well as the development of hadron cascades after hadronization. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time-development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position-space, momentum-space and color-space. The parton-evolution is described in terms of a space-time generalization of the familiar momentum-space description of multiple (semi)hard interactions inmore » QCD, involving 2 {r_arrow} 2 parton collisions, 2 {r_arrow} 1 parton fusion processes, and 1 {r_arrow} 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. Finally, the cascading of produced prehadronic clusters and of hadrons includes a multitude of 2 {r_arrow} n processes, and is modeled in parallel to the parton cascade description. This paper gives a brief review of the physics underlying VNI, as well as a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including simple examples), annotates input and control parameters, and discusses output data provided by it.« less

Focused conformational sampling in proteins

NASA Astrophysics Data System (ADS)

Bacci, Marco; Langini, Cassiano; Vymětal, Jiří; Caflisch, Amedeo; Vitalis, Andreas

2017-11-01

A detailed understanding of the conformational dynamics of biological molecules is difficult to obtain by experimental techniques due to resolution limitations in both time and space. Computer simulations avoid these in theory but are often too short to sample rare events reliably. Here we show that the progress index-guided sampling (PIGS) protocol can be used to enhance the sampling of rare events in selected parts of biomolecules without perturbing the remainder of the system. The method is very easy to use as it only requires as essential input a set of several features representing the parts of interest sufficiently. In this feature space, new states are discovered by spontaneous fluctuations alone and in unsupervised fashion. Because there are no energetic biases acting on phase space variables or projections thereof, the trajectories PIGS generates can be analyzed directly in the framework of transition networks. We demonstrate the possibility and usefulness of such focused explorations of biomolecules with two loops that are part of the binding sites of bromodomains, a family of epigenetic "reader" modules. This real-life application uncovers states that are structurally and kinetically far away from the initial crystallographic structures and are also metastable. Representative conformations are intended to be used in future high-throughput virtual screening campaigns.

Determination of space use by laying hens using kinematic analysis.

PubMed

Mench, Joy A; Blatchford, Richard A

2014-04-01

Two states in the United States now have legislation requiring that laying hens be provided with sufficient space to perform particular behaviors. To provide a framework for translating these performance standards into a space requirement, kinematic analysis was used to measure the amount of space needed for White Leghorn hens to stand, turn around 180°, lie down, and wing flap. Hyline W-36 hens (n = 9) were marked on the tops of their heads and the tips of both wings and 3 toes with black livestock marker. Each hen was then placed in a floor pen (91.4 × 91.4 cm) and filmed using 2 high-speed cameras. The resulting images were processed using a software program that generated 3-dimensional space use for each behavior. Because none of the hens lay down in the test pen, the 2-dimensional space required for lying was determined by superimposing a grid over videos of the hens lying down in their home cages. On average, hens required a mean area of 563 (± 8) cm(2) to stand, 1,316 (± 23) cm(2) to turn around, 318 (± 6) cm(2) to lie down, and 1,693 (± 136) cm(2) to wing flap. The mean heights used were 34.8 (± 1.3) cm for standing, 38.6 (± 2.3) cm for turning, and 49.5 (± 1.8) cm for wing flapping. However, space requirements for hens housed in multiple-hen groups in cage or noncage systems cannot be based simply on information about the space required for local movement by a single hen. It must also incorporate consideration of the tendency of hens in a flock to synchronize their behaviors. In addition, it must include not just local movement space but also the space that hens may need to use for longer-distance movements to access resources such as food, water, perches, and nest boxes.

Spectroscopic studies of non-thermal plasma jet at atmospheric pressure formed in low-current nonsteady-state plasmatron for biomedical applications

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

Demkin, V. P.; Melnichuk, S. V.; Demkin, O. V.

The optical and electrophysical characteristics of the nonequilibrium low-temperature plasma formed by a low-current nonsteady-state plasmatron are experimentally investigated in the present work. It is demonstrated that experimental data on the optical diagnostics of the plasma jet can provide a basis for the construction of a self-consistent physical and mathematical plasma model and for the creation of plasma sources with controllable electrophysical parameters intended for the generation of the required concentration of active particles. Results of spectroscopic diagnostics of plasma of the low-current nonsteady-state plasmatron confirm that the given source is efficient for the generation of charged particles and short-wavelengthmore » radiation—important plasma components for biomedical problems of an increase in the efficiency of treatment of biological tissues by charged particles. Measurement of the spatial distribution of the plasma jet potential by the probe method has demonstrated that a negative space charge is formed in the plasma jet possibly due to the formation of electronegative oxygen ions.« less

Oxygen Generation Assembly Technology Development

NASA Technical Reports Server (NTRS)

Bagdigian, Robert; Cloud, Dale

1999-01-01

Hamilton Standard Space Systems International (HSSI) is under contract to NASA Marshall Space Flight Center (MSFC) to develop an Oxygen Generation Assembly (OGA) for the International Space Station (ISS). The International Space Station Oxygen Generation Assembly (OGA) electrolyzes potable water from the Water Recovery System (WRS) to provide gaseous oxygen to the Space Station module atmosphere. The OGA produces oxygen for metabolic consumption by crew and biological specimens. The OGA also replenishes oxygen lost by experiment ingestion, airlock depressurization, CO2 venting, and leakage. As a byproduct, gaseous hydrogen is generated. The hydrogen will be supplied at a specified pressure range above ambient to support future utilization. Initially, the hydrogen will be vented overboard to space vacuum. This paper describes the OGA integration into the ISS Node 3. It details the development history supporting the design and describes the OGA System characteristics and its physical layout.

Requirements for Simulating Space Radiation With Particle Accelerators

NASA Technical Reports Server (NTRS)

Schimmerling, W.; Wilson, J. W.; Cucinotta, F.; Kim, M-H Y.

2004-01-01

Interplanetary space radiation consists of fully ionized nuclei of atomic elements with high energy for which only the few lowest energy ions can be stopped in shielding materials. The health risk from exposure to these ions and their secondary radiations generated in the materials of spacecraft and planetary surface enclosures is a major limiting factor in the management of space radiation risk. Accurate risk prediction depends on a knowledge of basic radiobiological mechanisms and how they are modified in the living tissues of a whole organism. To a large extent, this knowledge is not currently available. It is best developed at ground-based laboratories, using particle accelerator beams to simulate the components of space radiation. Different particles, in different energy regions, are required to study different biological effects, including beams of argon and iron nuclei in the energy range 600 to several thousand MeV/nucleon and carbon beams in the energy range of approximately 100 MeV/nucleon to approximately 1000 MeV/nucleon. Three facilities, one each in the United States, in Germany and in Japan, currently have the partial capability to satisfy these constraints. A facility has been proposed using the Brookhaven National Laboratory Booster Synchrotron in the United States; in conjunction with other on-site accelerators, it will be able to provide the full range of heavy ion beams and energies required. International cooperation in the use of these facilities is essential to the development of a safe international space program.

Learning Without Boundaries: A NASA - National Guard Bureau Distance Learning Partnership

NASA Technical Reports Server (NTRS)

Anderson, Susan H.; Chilelli, Christopher J.; Picard, Stephan

2003-01-01

With a variety of high-quality live interactive educational programs originating at the Johnson Space Center in Houston, Texas and other space and research centers, the US space agency NASA (National Aeronautics and Space Administration) has a proud track record of connecting with students throughout the world and stimulating their creativity and collaborative skills by teaching them underlying scientific and technological underpinnings of space exploration. However, NASA desires to expand its outreach capability for this type of interactive instruction. In early 2002, NASA and the National Guard Bureau -- using the Guard's nationwide system of state-ofthe-art classrooms and high bandwidth network -- began a collaboration to extend the reach of NASA content and educational programs to more of America's young people. Already, hundreds of elementary, middle, and high school students have visited Guard e-Learning facilities and participated in interactive NASA learning events. Topics have included experimental flight, satellite imagery-interpretation, and Mars exploration. Through this partnership, NASA and the National Guard are enabling local school systems throughout the United States (and, increasingly, the world) to use the excitement of space flight to encourage their students to become passionate about the possibility of one day serving as scientists, mathematicians, technologists, and engineers. At the 54th International Astronautical Conference MAJ Stephan Picard, the guiding visionary behind the Guard's partnership with NASA, and Chris Chilelli, an educator and senior instructional designer at NASA, will share with attendees background on NASA's educational products and the National Guard's distributed learning network; will discuss the unique opportunity this partnership already has provided students and teachers throughout the United States; will offer insights into the formation by government entities of e-Learning partnerships with one another; and will suggest a possible future for the NASA - National Guard Bureau partnership, one potentially to include live multi-party interaction of hundreds of students in several countries with astronauts, scientists, engineers and designers. To inspire the next generation of explorers as only NASA can!

Multi-Spacecraft Autonomous Positioning System

NASA Technical Reports Server (NTRS)

Anzalone, Evan

2015-01-01

As the number of spacecraft in simultaneous operation continues to grow, there is an increased dependency on ground-based navigation support. The current baseline system for deep space navigation utilizes Earth-based radiometric tracking, requiring long-duration observations to perform orbit determination and generate a state update. The age, complexity, and high utilization of the ground assets pose a risk to spacecraft navigation performance. In order to perform complex operations at large distances from Earth, such as extraterrestrial landing and proximity operations, autonomous systems are required. With increasingly complex mission operations, the need for frequent and Earth-independent navigation capabilities is further reinforced. The Multi-spacecraft Autonomous Positioning System (MAPS) takes advantage of the growing interspacecraft communication network and infrastructure to allow for Earth-autonomous state measurements to enable network-based space navigation. A notional concept of operations is given in figure 1. This network is already being implemented and routinely used in Martian communications through the use of the Mars Reconnaissance Orbiter and Mars Odyssey spacecraft as relays for surface assets. The growth of this communications architecture is continued through MAVEN, and future potential commercial Mars telecom orbiters. This growing network provides an initial Marslocal capability for inter-spacecraft communication and navigation. These navigation updates are enabled by cross-communication between assets in the network, coupled with onboard navigation estimation routines to integrate packet travel time to generate ranging measurements. Inter-spacecraft communication allows for frequent state broadcasts and time updates from trusted references. The architecture is a software-based solution, enabling its implementation on a wide variety of current assets, with the operational constraints and measurement accuracy determined by onboard systems.

Advanced technologies in the ASI MLRO towards a new generation laser ranging system

NASA Technical Reports Server (NTRS)

Varghese, Thomas; Bianco, Giuseppe

1994-01-01

Matera Laser Ranging Observatory (MLRO) is a high performance, highly automated optical and astronomical observatory currently under design and development by AlliedSignal for the Italian Space Agency (ASI). It is projected to become operational at the Centro Geodesia Spaziale in Matera, Italy, in 1997. MLRO, based on a 1.5-meter astronomical quality telescope, will perform ranging to spacecraft in earthbound orbits, lunar reflectors, and specially equipped deep space missions. The primary emphasis during design is to incorporate state-of-the-art technologies to produce an intelligent, automated, high accuracy ranging system that will mimic the characteristic features of a fifth generation laser ranging system. The telescope has multiple ports and foci to support future experiments in the areas of laser communications, lidar, astrometry, etc. The key features providing state-of-the-art ranging performance include: a diode-pumped picosecond (50 ps) laser, high speed (3-5 GHz) optoelectronic detection and signal processing, and a high accuracy (6 ps) high resolution (less than 2 ps) time measurement capability. The above combination of technologies is expected to yield millimeter laser ranging precision and accuracy on targets up to 300,000 km, surpassing the best operational instrument performance to date by a factor of five or more. Distributed processing and control using a state-of-the-art computing environment provides the framework for efficient operation, system optimization, and diagnostics. A computationally intelligent environment permits optimal planning, scheduling, tracking, and data processing. It also supports remote access, monitor, and control for joint experiments with other observatories.

Operational Considerations and Comparisons of the Saturn, Space Shuttle and Ares Launch Vehicles

NASA Technical Reports Server (NTRS)

Cruzen, Craig; Chavers, Greg; Wittenstein, Jerry

2009-01-01

The United States (U.S.) space exploration policy has directed the National Aeronautics and Space Administration (NASA) to retire the Space Shuttle and to replace it with a new generation of space transportation systems for crew and cargo travel to the International Space Station, the Moon, Mars, and beyond. As part of the Constellation Program, engineers at NASA's Marshall Space Flight Center in Huntsville, Alabama are working to design and build the Ares I, the first of two large launch vehicles to return humans to the Moon. A deliberate effort is being made to ensure a high level of operability in order to significantly increase safety and availability as well as reduce recurring costs of this new launch vehicle. It is the Ares Project's goal to instill operability as part of the requirements development, design and operations of the vehicle. This paper will identify important factors in launch vehicle design that affect the operability and availability of the system. Similarities and differences in operational constraints will also be compared between the Saturn V, Space Shuttle and current Ares I design. Finally, potential improvements in operations and operability for large launch vehicles will be addressed. From the examples presented, the paper will discuss potential improvements for operability for future launch vehicles.

Space Weather Modeling Services at the Community Coordinated Modeling Center

NASA Technical Reports Server (NTRS)

Hesse, Michael

2006-01-01

The Community Coordinated Modeling Center (CCMC) is a multi-agency partnership, which aims at the creation of next generation space weather models. The goal of the CCMC is to support the research and developmental work necessary to substantially increase the present-day modeling capability for space weather purposes, and to provide models for transition to the Rapid Prototyping Centers at the space weather forecast centers. This goal requires close collaborations with and substantial involvement of the research community. The physical regions to be addressed by CCMC-related activities range from the solar atmosphere to the Earth's upper atmosphere. The CCMC is an integral part of the National Space Weather Program Implementation Plan, of NASA's Living With a Star (LWS) initiative, and of the Department of Defense Space Weather Transition Plan. CCMC includes a facility at NASA Goddard Space Flight Center. CCMC also provides, to the research community, access to state-of-the-art space research models. In this paper we will provide a description of the current CCMC status, discuss current plans, research and development accomplishments and goals, and describe the model testing and validation process undertaken as part of the CCMC mandate. Special emphasis will be on solar and heliospheric models currently residing at CCMC, and on plans for validation and verification.

Space Weather Modeling at the Community Coordinated Modeling Center

NASA Technical Reports Server (NTRS)

Hesse M.

2005-01-01

The Community Coordinated Modeling Center (CCMC) is a multi-agency partnership, which aims at the creation of next generation space weather models. The goal of the CCMC is to support the research and developmental work necessary to substantially increase the present-day modeling capability for space weather purposes, and to provide models for transition to the rapid prototyping centers at the space weather forecast centers. This goal requires dose collaborations with and substantial involvement of the research community. The physical regions to be addressed by CCMC-related activities range from the solar atmosphere to the Earth's upper atmosphere. The CCMC is an integral part of the National Space Weather Program Implementation Plan, of NASA's Living With a Star (LWS) initiative, and of the Department of Defense Space Weather Transition Plan. CCMC includes a facility at NASA Goddard Space Flight Center, as well as distributed computing facilities provided by the US Air Force. CCMC also provides, to the research community, access to state-of-the-art space research models. In this paper we will provide updates on CCMC status, on current plans, research and development accomplishments and goals, and on the model testing and validation process undertaken as part of the CCMC mandate. Special emphasis will be on solar and heliospheric models currently residing at CCMC, and on plans for validation and verification.

Advanced Space Transportation Program (ASTP)

NASA Image and Video Library

2002-10-01

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Space Launch Initiative (SLI), NASA's priority developmental program focused on empowering America's leadership in space. SLI includes commercial, higher education, and defense partnerships and contracts to offer widespread participation in both the risk and success of developing our nation's next-generation reusable launch vehicle. This photo depicts an artist's concept of a future second-generation launch vehicle. For the SLI, architecture definition includes all components of the next-generation reusable launch system: Earth-to-orbit vehicles (the Space Shuttle is the first generation earth-to-orbit vehicle), crew transfer vehicles, transfer stages, ground processing systems, flight operations systems, and development of business case strategies. Three contractor teams have each been funded to develop potential second- generation reusable launch system architectures: The Boeing Company of Seal Beach, California; Lockheed Martin Corporation of Denver, Colorado along with a team including Northrop Grumman of El Segundo, California; and Orbital Sciences Corporation of Dulles, Virginia.

Advanced Space Transportation Program (ASTP)

NASA Image and Video Library

2002-10-01

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Space Launch Initiative (SLI), NASA's priority developmental program focused on empowering America's leadership in space. SLI includes commercial, higher education and defense partnerships and contracts to offer widespread participation in both the risk and success of developing our nation's next-generation reusable launch vehicle. This photo depicts an artist's concept of a future second-generation launch vehicle during separation of stages. For SLI, architecture definition includes all components of the next-generation reusable launch system: Earth-to-orbit vehicles (the Space Shuttle is the first-generation earth-to-orbit vehicle), crew transfer vehicles, transfer stages, ground processing systems, flight operations systems, and development of business case strategies. Three contractor teams have each been funded to develop potential second generation reusable launch system architectures: The Boeing Company of Seal Beach, California; Lockheed Martin Corporation of Denver, Colorado; a team including Northrop Grumman of El Segundo, California; and Orbital Sciences Corporation of Dulles, Virginia.

A Novel Controller Design for the Next Generation Space Electrostatic Accelerometer Based on Disturbance Observation and Rejection.

PubMed

Li, Hongyin; Bai, Yanzheng; Hu, Ming; Luo, Yingxin; Zhou, Zebing

2016-12-23

The state-of-the-art accelerometer technology has been widely applied in space missions. The performance of the next generation accelerometer in future geodesic satellites is pushed to 8 × 10 - 13 m / s 2 / H z 1 / 2 , which is close to the hardware fundamental limit. According to the instrument noise budget, the geodesic test mass must be kept in the center of the accelerometer within the bounds of 56 pm / Hz 1 / 2 by the feedback controller. The unprecedented control requirements and necessity for the integration of calibration functions calls for a new type of control scheme with more flexibility and robustness. A novel digital controller design for the next generation electrostatic accelerometers based on disturbance observation and rejection with the well-studied Embedded Model Control (EMC) methodology is presented. The parameters are optimized automatically using a non-smooth optimization toolbox and setting a weighted H-infinity norm as the target. The precise frequency performance requirement of the accelerometer is well met during the batch auto-tuning, and a series of controllers for multiple working modes is generated. Simulation results show that the novel controller could obtain not only better disturbance rejection performance than the traditional Proportional Integral Derivative (PID) controllers, but also new instrument functions, including: easier tuning procedure, separation of measurement and control bandwidth and smooth control parameter switching.

A Novel Controller Design for the Next Generation Space Electrostatic Accelerometer Based on Disturbance Observation and Rejection

PubMed Central

Li, Hongyin; Bai, Yanzheng; Hu, Ming; Luo, Yingxin; Zhou, Zebing

2016-01-01

The state-of-the-art accelerometer technology has been widely applied in space missions. The performance of the next generation accelerometer in future geodesic satellites is pushed to 8×10−13m/s2/Hz1/2, which is close to the hardware fundamental limit. According to the instrument noise budget, the geodesic test mass must be kept in the center of the accelerometer within the bounds of 56 pm/Hz1/2 by the feedback controller. The unprecedented control requirements and necessity for the integration of calibration functions calls for a new type of control scheme with more flexibility and robustness. A novel digital controller design for the next generation electrostatic accelerometers based on disturbance observation and rejection with the well-studied Embedded Model Control (EMC) methodology is presented. The parameters are optimized automatically using a non-smooth optimization toolbox and setting a weighted H-infinity norm as the target. The precise frequency performance requirement of the accelerometer is well met during the batch auto-tuning, and a series of controllers for multiple working modes is generated. Simulation results show that the novel controller could obtain not only better disturbance rejection performance than the traditional Proportional Integral Derivative (PID) controllers, but also new instrument functions, including: easier tuning procedure, separation of measurement and control bandwidth and smooth control parameter switching. PMID:28025534

Source-reconstruction of the sensorimotor network from resting-state macaque electrocorticography.

PubMed

Hindriks, R; Micheli, C; Bosman, C A; Oostenveld, R; Lewis, C; Mantini, D; Fries, P; Deco, G

2018-06-07

The discovery of hemodynamic (BOLD-fMRI) resting-state networks (RSNs) has brought about a fundamental shift in our thinking about the role of intrinsic brain activity. The electrophysiological underpinnings of RSNs remain largely elusive and it has been shown only recently that electric cortical rhythms are organized into the same RSNs as hemodynamic signals. Most electrophysiological studies into RSNs use magnetoencephalography (MEG) or scalp electroencephalography (EEG), which limits the spatial resolution with which electrophysiological RSNs can be observed. Due to their close proximity to the cortical surface, electrocorticographic (ECoG) recordings can potentially provide a more detailed picture of the functional organization of resting-state cortical rhythms, albeit at the expense of spatial coverage. In this study we propose using source-space spatial independent component analysis (spatial ICA) for identifying generators of resting-state cortical rhythms as recorded with ECoG and for reconstructing their functional connectivity. Network structure is assessed by two kinds of connectivity measures: instantaneous correlations between band-limited amplitude envelopes and oscillatory phase-locking. By simulating rhythmic cortical generators, we find that the reconstruction of oscillatory phase-locking is more challenging than that of amplitude correlations, particularly for low signal-to-noise levels. Specifically, phase-lags can both be over- and underestimated, which troubles the interpretation of lag-based connectivity measures. We illustrate the methodology on somatosensory beta rhythms recorded from a macaque monkey using ECoG. The methodology decomposes the resting-state sensorimotor network into three cortical generators, distributed across primary somatosensory and primary and higher-order motor areas. The generators display significant and reproducible amplitude correlations and phase-locking values with non-zero lags. Our findings illustrate the level of spatial detail attainable with source-projected ECoG and motivates wider use of the methodology for studying resting-state as well as event-related cortical dynamics in macaque and human. Copyright © 2018. Published by Elsevier Inc.

Area law from loop quantum gravity

NASA Astrophysics Data System (ADS)

Hamma, Alioscia; Hung, Ling-Yan; Marcianò, Antonino; Zhang, Mingyi

2018-03-01

We explore the constraints following from requiring the area law in the entanglement entropy in the context of loop quantum gravity. We find a unique solution to the single-link wave function in the large j limit, believed to be appropriate in the semiclassical limit. We then generalize our considerations to multilink coherent states, and find that the area law is preserved very generically using our single-link wave function as a building block. Finally, we develop the framework that generates families of multilink states that preserve the area law while avoiding macroscopic entanglement, the space-time analogue of "Schrödinger's cat." We note that these states, defined on a given set of graphs, are the ground states of some local Hamiltonian that can be constructed explicitly. This can potentially shed light on the construction of the appropriate Hamiltonian constraints in the LQG framework.

Oregon Magnetic and Gravity Maps and Data: A Web Site for Distribution of Data

USGS Publications Warehouse

Roberts, Carter W.; Kucks, Robert P.; Hill, Patricia L.

2008-01-01

This web site gives the results of a USGS project to acquire the best available, public-domain, aeromagnetic and gravity data in the United States and merge these data into uniform, composite grids for each State. The results for the State of Oregon are presented here on this site. Files of aeromagnetic and gravity grids and images are available for these States for downloading. In Oregon, 49 magnetic surveys have been knit together to form a single digital grid and map. Also, a complete Bouguer gravity anomaly grid and map was generated from 40,665 gravity station measurements in and adjacent to Oregon. In addition, a map shows the location of the aeromagnetic surveys, color-coded to the survey flight-line spacing. This project was supported by the Mineral Resource Program of the USGS.

Total-dose radiation effects data for semiconductor devices: 1985 supplement, volume 1

NASA Technical Reports Server (NTRS)

Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

1985-01-01

Steady-state, total-dose radiation test data are provided, in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. The document is in two volumes: Volume 1 provides data on diodes, bipolar transistors, field effect transistors, and miscellaneous semiconductor types, and Volume 2 provides total-dose radiation test data on integrated circuits. Volume 1 of this 1985 Supplement contains new total-dose radiation test data generated since the August 1, 1981 release date of the original Volume 1. Publication of Volume 2 of the 1985 Supplement will follow that of Volume 1 by approximately three months.

The Analysis of Fluorescence Decay by a Method of Moments

PubMed Central

Isenberg, Irvin; Dyson, Robert D.

1969-01-01

The fluorescence decay of the excited state of most biopolymers, and biopolymer conjugates and complexes, is not, in general, a simple exponential. The method of moments is used to establish a means of analyzing such multi-exponential decays. The method is tested by the use of computer simulated data, assuming that the limiting error is determined by noise generated by a pseudorandom number generator. Multi-exponential systems with relatively closely spaced decay constants may be successfully analyzed. The analyses show the requirements, in terms of precision, that data must meet. The results may be used both as an aid in the design of equipment and in the analysis of data subsequently obtained. PMID:5353139

Thermal and Structural Analysis of Micro-Fabricated Involute Regenerators

NASA Astrophysics Data System (ADS)

Qiu, Songgang; Augenblick, Jack E.

2005-02-01

Long-life, high-efficiency power generators based on free-piston Stirling engines are an energy conversion solution for future space power generation and commercial applications. As part of the efforts to further improve Stirling engine efficiency and reliability, a micro-fabricated, involute regenerator structure is proposed by a Cleveland State University-led regenerator research team. This paper reports on thermal and structural analyses of the involute regenerator to demonstrate the feasibility of the proposed regenerator. The results indicate that the involute regenerator has extremely high axial stiffness to sustain reasonable axial compression forces with negligible lateral deformation. The relatively low radial stiffness may impose some challenges to the appropriate installation of the in-volute regenerators.

Safe, Affordable, Nuclear Thermal Propulsion Systems

NASA Technical Reports Server (NTRS)

Houts, M. G.; Kim, T.; Emrich, W. J.; Hickman, R. R.; Broadway, J. W.; Gerrish, H. P.; Doughty, G. E.

2014-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on NTP could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of the NCPS in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progress made under the NCPS project could help enable both advanced NTP and advanced Nuclear Electric Propulsion (NEP).

The Nuclear Cryogenic Propulsion Stage

NASA Technical Reports Server (NTRS)

Houts, Michael G.; Kim, Tony; Emrich, William J.; Hickman, Robert R.; Broadway, Jeramie W.; Gerrish, Harold P.; Doughty, Glen; Belvin, Anthony; Borowski, Stanley K.; Scott, John

2014-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on NTP could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of the NCPS in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progres made under the NCPS project could help enable both advanced NTP and advanced Nuclear Electric Propulsion (NEP).

Nuclear Cryogenic Propulsion Stage for Mars Exploration

NASA Technical Reports Server (NTRS)

Houts, M. G.; Borowski, S. K.; George, J. A.; Kim, T.; Emrich, W. J.; Hickman, R. R.; Broadway, J. W.; Gerrish, H. P.; Adams, R. B.

2012-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on NTP could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of the NCPS in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progress made under the NCPS project could help enable both advanced NTP and advanced Nuclear Electric Propulsion (NEP).

Enabling the 2nd Generation in Space: Building Blocks for Large Scale Space Endeavours

NASA Astrophysics Data System (ADS)

Barnhardt, D.; Garretson, P.; Will, P.

Today the world operates within a "first generation" space industrial enterprise, i.e. all industry is on Earth, all value from space is from bits (data essentially), and the focus is Earth-centric, with very limited parts of our population and industry participating in space. We are limited in access, manoeuvring, on-orbit servicing, in-space power, in-space manufacturing and assembly. The transition to a "Starship culture" requires the Earth to progress to a "second generation" space industrial base, which implies the need to expand the economic sphere of activity of mankind outside of an Earth-centric zone and into CIS-lunar space and beyond, with an equal ability to tap the indigenous resources in space (energy, location, materials) that will contribute to an expanding space economy. Right now, there is no comfortable place for space applications that are not discovery science, exploration, military, or established earth bound services. For the most part, space applications leave out -- or at least leave nebulous, unconsolidated, and without a critical mass -- programs and development efforts for infrastructure, industrialization, space resources (survey and process maturation), non-traditional and persistent security situational awareness, and global utilities -- all of which, to a far greater extent than a discovery and exploration program, may help determine the elements of a 2nd generation space capability. We propose a focus to seed the pre-competitive research that will enable global industry to develop the necessary competencies that we currently lack to build large scale space structures on-orbit, that in turn would lay the foundation for long duration spacecraft travel (i.e. key technologies in access, manoeuvrability, etc.). This paper will posit a vision-to-reality for a step wise approach to the types of activities the US and global space providers could embark upon to lay the foundation for the 2nd generation of Earth in space.

A Generalized Quantum Theory

NASA Astrophysics Data System (ADS)

Niestegge, Gerd

2014-09-01

In quantum mechanics, the selfadjoint Hilbert space operators play a triple role as observables, generators of the dynamical groups and statistical operators defining the mixed states. One might expect that this is typical of Hilbert space quantum mechanics, but it is not. The same triple role occurs for the elements of a certain ordered Banach space in a much more general theory based upon quantum logics and a conditional probability calculus (which is a quantum logical model of the Lueders-von Neumann measurement process). It is shown how positive groups, automorphism groups, Lie algebras and statistical operators emerge from one major postulate - the non-existence of third-order interference (third-order interference and its impossibility in quantum mechanics were discovered by R. Sorkin in 1994). This again underlines the power of the combination of the conditional probability calculus with the postulate that there is no third-order interference. In two earlier papers, its impact on contextuality and nonlocality had already been revealed.

AIRSAR South American deployment: Operation plan, version 3.0

NASA Technical Reports Server (NTRS)

Kobrick, M.

1993-01-01

The United States National Aeronautics and Space Administration (NASA) and the Brazilian Commission for Space Activities (COBAE) are undertaking a joint experiment involving NASA's DC-8 research aircraft and the Airborne Synthetic Aperture Radar (AIRSAR) system during late May and June 1993. The research areas motivating these activities are: (1) fundamental research in the role of soils, vegetation, and hydrology in the global carbon cycle; and (2) in cooperation with South American scientists, airborne remote sensing research for the upcoming NASA Spaceborne Imaging Radar (SIR)-C/X-SAR flights on the Space Shuttle. A flight schedule and plans for the deployment that were developed are included. Maps of the site locations and schematic indications of flight routes and dates, plots showing swath locations derived from the flight requests and generated by flight planning software, and, most importantly, a calendar showing which sites will be imaged each day are included.

Educating and Inspiring Young People for the Next Generation of Exploration

NASA Technical Reports Server (NTRS)

Armstrong, Robert C., Jr.

2007-01-01

With the graying of the nation's scientific workforce and the decline in students pursuing science, technological, engineering, and math related-studies, real challenges lie ahead if America is to continue to sustain the Vision for Space Exploration in the foreseeable future. Likewise, challenges exist in the economic arena as the United States seeks to maintain its preeminence among the technological leaders of the world. Currently, less than 6 percent of high school seniors are pursuing engineering degrees, down from 36 percent a decade ago. Today, China produces six times as many engineers as does the United States and Japan, at half our population, develops twice as many engineers. Despite spending more per capita on public education than any other nation, except Switzerland, U.S. students of high school age are failing to compete with many foreign countries. These trends do not bode well for America's future competitiveness in space and other technically driven areas, such as defense.

1985 Annual Conference on Nuclear and Space Radiation Effects, 22nd, Monterey, CA, July 22-24, 1985, Proceedings

NASA Technical Reports Server (NTRS)

Jones, C. W. (Editor)

1985-01-01

Basic mechanisms of radiation effects in structures and materials are discussed, taking into account the time dependence of interface state production, process dependent build-up of interface states in irradiated N-channel MOSFETs, bias annealing of radiation and bias induced positive charges in n- and p-type MOS capacitors, hole removal in thin-gate MOSFETs by tunneling, and activation energies of oxide charge recovery in SOS or SOI structures after an ionizing pulse. Other topics investigated are related to radiation effects in devices, radiation effects in integrated circuits, spacecraft charging and space radiation effects, single-event phenomena, hardness assurance and radiation sources, SGEMP/IEMP phenomena, EMP phenomena, and dosimetry and energy-dependent effects. Attention is given to a model of the plasma wake generated by a large object, gate charge collection and induced drain current in GaAs FETs, simulation of charge collection in a multilayer device, and time dependent dose enhancement effects on integrated circuit transient response mechanisms.

Space-time least-squares finite element method for convection-reaction system with transformed variables

PubMed Central

Nam, Jaewook

2011-01-01

We present a method to solve a convection-reaction system based on a least-squares finite element method (LSFEM). For steady-state computations, issues related to recirculation flow are stated and demonstrated with a simple example. The method can compute concentration profiles in open flow even when the generation term is small. This is the case for estimating hemolysis in blood. Time-dependent flows are computed with the space-time LSFEM discretization. We observe that the computed hemoglobin concentration can become negative in certain regions of the flow; it is a physically unacceptable result. To prevent this, we propose a quadratic transformation of variables. The transformed governing equation can be solved in a straightforward way by LSFEM with no sign of unphysical behavior. The effect of localized high shear on blood damage is shown in a circular Couette-flow-with-blade configuration, and a physiological condition is tested in an arterial graft flow. PMID:21709752

Singularity and steering logic for control moment gyros on flexible space structures

NASA Astrophysics Data System (ADS)

Hu, Quan; Guo, Chuandong; Zhang, Jun

2017-08-01

Control moment gyros (CMGs) are a widely used device for generating control torques for spacecraft attitude control without expending propellant. Because of its effectiveness and cleanness, it has been considered to be mounted on a space structure for active vibration suppression. The resultant system is the so-called gyroelastic body. Since CMGs could exert both torque and modal force to the structure, it can also be used to simultaneously achieve attitude maneuver and vibration reduction of a flexible spacecraft. In this paper, we consider the singularity problem in such application of CMGs. The dynamics of an unconstrained gyroelastic body is established, from which the output equations of the CMGs are extracted. Then, torque singular state and modal force singular state are defined and visualized to demonstrate the singularity. Numerical examples of several typical CMGs configurations on a gyroelastic body are given. Finally, a steering law allowing output error is designed and applied to the vibration suppression of a plate with distributed CMGs.

Parallelized reliability estimation of reconfigurable computer networks

NASA Technical Reports Server (NTRS)

Nicol, David M.; Das, Subhendu; Palumbo, Dan

1990-01-01

A parallelized system, ASSURE, for computing the reliability of embedded avionics flight control systems which are able to reconfigure themselves in the event of failure is described. ASSURE accepts a grammar that describes a reliability semi-Markov state-space. From this it creates a parallel program that simultaneously generates and analyzes the state-space, placing upper and lower bounds on the probability of system failure. ASSURE is implemented on a 32-node Intel iPSC/860, and has achieved high processor efficiencies on real problems. Through a combination of improved algorithms, exploitation of parallelism, and use of an advanced microprocessor architecture, ASSURE has reduced the execution time on substantial problems by a factor of one thousand over previous workstation implementations. Furthermore, ASSURE's parallel execution rate on the iPSC/860 is an order of magnitude faster than its serial execution rate on a Cray-2 supercomputer. While dynamic load balancing is necessary for ASSURE's good performance, it is needed only infrequently; the particular method of load balancing used does not substantially affect performance.

Electrical characterizations of MIS structures based on variable-gap n(p)-HgCdTe grown by MBE on Si(0 1 3) substrates

NASA Astrophysics Data System (ADS)

Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.; Varavin, V. S.; Dvoretskii, S. A.; Mikhailov, N. N.; Yakushev, M. V.; Sidorov, G. Yu.

2017-12-01

Metal-insulator-semiconductor (MIS) structures based on n(p)-Hg1-xCdxTe (x = 0.22-0.40) with near-surface variable-gap layers were grown by the molecular-beam epitaxy (MBE) technique on the Si (0 1 3) substrates. Electrical properties of MIS structures were investigated experimentally at various temperatures (9-77 K) and directions of voltage sweep. The ;narrow swing; technique was used to determine the spectra of fast surface states with the exception of hysteresis effects. It is established that the density of fast surface states at the MCT/Al2O3 interface at a minimum does not exceed 3 × 1010 eV-1 × cm-2. For MIS structures based on n-MCT/Si(0 1 3), the differential resistance of the space-charge region in strong inversion mode in the temperature range 50-90 K is limited by the Shockley-Read-Hall generation in the space-charge region.

1985 Annual Conference on Nuclear and Space Radiation Effects, 22nd, Monterey, CA, July 22-24, 1985, Proceedings

NASA Astrophysics Data System (ADS)

Jones, C. W.

1985-12-01

Basic mechanisms of radiation effects in structures and materials are discussed, taking into account the time dependence of interface state production, process dependent build-up of interface states in irradiated N-channel MOSFETs, bias annealing of radiation and bias induced positive charges in n- and p-type MOS capacitors, hole removal in thin-gate MOSFETs by tunneling, and activation energies of oxide charge recovery in SOS or SOI structures after an ionizing pulse. Other topics investigated are related to radiation effects in devices, radiation effects in integrated circuits, spacecraft charging and space radiation effects, single-event phenomena, hardness assurance and radiation sources, SGEMP/IEMP phenomena, EMP phenomena, and dosimetry and energy-dependent effects. Attention is given to a model of the plasma wake generated by a large object, gate charge collection and induced drain current in GaAs FETs, simulation of charge collection in a multilayer device, and time dependent dose enhancement effects on integrated circuit transient response mechanisms.

Evaluation of Computer Aided Vortex Forecast System

NASA Technical Reports Server (NTRS)

Rossow, Vernon J.; Olson, Lawrence E. (Technical Monitor)

1995-01-01

Several countries, including the United States. Canada, Germany, England and Russia, are in the process of trying to develop some sort of computer-aided system that will guide controllers at airports on the hazard posed by lift-generated vortices that trail behind subsonic transport aircraft. The emphasis on this particular subject has come about because the hazard posed by wake vortices is currently the only reason why aircraft are spaced at 3 to 6 miles apart during landing and takeoff rather than something like 2 miles. It is well known that under certain weather conditions, aircraft spacings can be safely reduced to as little as the desired 2 miles. In an effort to perhaps capitalize on such a possibility, a combined FAA and NASA program is currently underway in the United States to develop such a system. Needless to say, the problems associated with anticipating the required separation distances when weather conditions are involved is very difficult. Similarly, Canada has a corresponding program to develop a vortex forecast system of their own.

Raetrad model extensions for radon entry into multi-level buildings with basements or crawl spaces.

PubMed

Nielson, K K; Rogers, V C; Rogers, V; Holt, R B

1997-10-01

The RAETRAD model was generalized to characterize radon generation and movement from soils and building materials into multi-level buildings with basements or crawl spaces. With the generalization, the model retains its original simplicity and ease of use. The model calculates radon entry rates that are consistent with measurements published for basement test structures at Colorado State University, confirming approximately equal contributions from diffusion and pressure-driven air flow at indoor-outdoor air pressure differences of deltaP(i-o) = -3.5 Pa. About one-fourth of the diffusive radon entry comes from concrete slabs and three-fourths comes from the surrounding soils. Calculated radon entry rates with and without a barrier over floor-wall shrinkage cracks generally agree with Colorado State University measurements when a sustained pressure of deltaP(i-o) = -2 Pa is used to represent calm wind (<1 m s(-1)) conditions. Calculated radon distributions in a 2-level house also are consistent with published measurements and equations.

Continuing Development for Free-Piston Stirling Space Power Systems

NASA Astrophysics Data System (ADS)

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

2004-02-01

Long-life radioisotope power generators based on free-piston Stirling engines are an energy-conversion solution for future space applications. The high efficiency of Stirling machines makes them more attractive than the thermoelectric generators currently used in space. Stirling Technology Company (STC) has been developing free-piston Stirling machines for over 30 years, and its family of Stirling generators is ideally suited for reliable, maintenance-free operation. This paper describes recent progress and status of the STC RemoteGen™ 55 W-class Stirling generator (RG-55), presents an overview of recent testing, and discusses how the technology demonstration design has evolved toward space-qualified hardware.

Understanding Epileptiform After-Discharges as Rhythmic Oscillatory Transients.

PubMed

Baier, Gerold; Taylor, Peter N; Wang, Yujiang

2017-01-01

Electro-cortical activity in patients with epilepsy may show abnormal rhythmic transients in response to stimulation. Even when using the same stimulation parameters in the same patient, wide variability in the duration of transient response has been reported. These transients have long been considered important for the mapping of the excitability levels in the epileptic brain but their dynamic mechanism is still not well understood. To investigate the occurrence of abnormal transients dynamically, we use a thalamo-cortical neural population model of epileptic spike-wave activity and study the interaction between slow and fast subsystems. In a reduced version of the thalamo-cortical model, slow wave oscillations arise from a fold of cycles (FoC) bifurcation. This marks the onset of a region of bistability between a high amplitude oscillatory rhythm and the background state. In vicinity of the bistability in parameter space, the model has excitable dynamics, showing prolonged rhythmic transients in response to suprathreshold pulse stimulation. We analyse the state space geometry of the bistable and excitable states, and find that the rhythmic transient arises when the impending FoC bifurcation deforms the state space and creates an area of locally reduced attraction to the fixed point. This area essentially allows trajectories to dwell there before escaping to the stable steady state, thus creating rhythmic transients. In the full thalamo-cortical model, we find a similar FoC bifurcation structure. Based on the analysis, we propose an explanation of why stimulation induced epileptiform activity may vary between trials, and predict how the variability could be related to ongoing oscillatory background activity. We compare our dynamic mechanism with other mechanisms (such as a slow parameter change) to generate excitable transients, and we discuss the proposed excitability mechanism in the context of stimulation responses in the epileptic cortex.