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1

Dynamics of Variable Mass Systems  

NASA Technical Reports Server (NTRS)

This report presents the results of an investigation of the effects of mass loss on the attitude behavior of spinning bodies in flight. The principal goal is to determine whether there are circumstances under which the motion of variable mass systems can become unstable in the sense that their transverse angular velocities become unbounded. Obviously, results from a study of this kind would find immediate application in the aerospace field. The first part of this study features a complete and mathematically rigorous derivation of a set of equations that govern both the translational and rotational motions of general variable mass systems. The remainder of the study is then devoted to the application of the equations obtained to a systematic investigation of the effect of various mass loss scenarios on the dynamics of increasingly complex models of variable mass systems. It is found that mass loss can have a major impact on the dynamics of mechanical systems, including a possible change in the systems stability picture. Factors such as nozzle geometry, combustion chamber geometry, propellant's initial shape, size and relative mass, and propellant location can all have important influences on the system's dynamic behavior. The relative importance of these parameters on-system motion are quantified in a way that is useful for design purposes.

Eke, Fidelis O.

1998-01-01

2

Dynamics of variable mass systems with application to the star 48 solid rocket motor  

NASA Technical Reports Server (NTRS)

Existing methods for the derivation of equations of motion of variable mass systems are reviewed and compared, the end product being a system of general dynamical equations for variable mass systems. These equations are used to study the lateral stability problem associated with the Star 48 solid rocket engine. It is shown that the shape of the combustion chamber could have a significant effect on the lateral stability of the rocket; specifically, a short and wide combustion chamber is destabilizing, while a long and narrow chamber is stabilizing.

Eke, F. O.

1984-01-01

3

Atwood's Machine as a Tool to Introduce Variable Mass Systems  

ERIC Educational Resources Information Center

This article discusses an instructional strategy which explores eventual similarities and/or analogies between familiar problems and more sophisticated systems. In this context, the Atwood's machine problem is used to introduce students to more complex problems involving ropes and chains. The methodology proposed helps students to develop the…

de Sousa, Celia A.

2012-01-01

4

Falling Chains as Variable-Mass Systems: Theoretical Model and Experimental Analysis  

ERIC Educational Resources Information Center

In this paper, we revisit, theoretically and experimentally, the fall of a folded U-chain and of a pile-chain. The model calculation implies the division of the whole system into two subsystems of variable mass, allowing us to explore the role of tensional contact forces at the boundary of the subsystems. This justifies, for instance, that the…

de Sousa, Celia A.; Gordo, Paulo M.; Costa, Pedro

2012-01-01

5

Deconstructed Transverse Mass Variables  

E-print Network

Traditional searches for R-parity conserving natural supersymmetry (SUSY) require large transverse mass and missing energy cuts to separate the signal from large backgrounds. SUSY models with compressed spectra inherently produce signal events with small amounts of missing energy that are hard to explore. We use this difficulty to motivate the construction of "deconstructed" transverse mass variables which are designed preserve information on both the norm and direction of the missing momentum. We demonstrate the effectiveness of these variables in searches for the pair production of supersymmetric top-quark partners which subsequently decay into a final state with an isolated lepton, jets and missing energy. We show that the use of deconstructed transverse mass variables extends the accessible compressed spectra parameter space beyond the region probed by traditional methods. The parameter space can further be expanded to neutralino masses that are larger than the difference between the stop and top masses. In addition, we also discuss how these variables allow for novel searches of single stop production, in order to directly probe unconstrained stealth stops in the small stop- and neutralino-mass regime. We also demonstrate the utility of these variables for generic gluino and stop searches in all-hadronic final states. Overall, we demonstrate that deconstructed transverse variables are essential to any search wanting to maximize signal separation from the background when the signal has undetected particles in the final state.

Ahmed Ismail; Reinhard Schwienhorst; Joseph S. Virzi; Devin G. E. Walker

2014-09-09

6

The dynamical mass of a classical Cepheid variable star in an eclipsing binary system.  

PubMed

Stellar pulsation theory provides a means of determining the masses of pulsating classical Cepheid supergiants-it is the pulsation that causes their luminosity to vary. Such pulsational masses are found to be smaller than the masses derived from stellar evolution theory: this is the Cepheid mass discrepancy problem, for which a solution is missing. An independent, accurate dynamical mass determination for a classical Cepheid variable star (as opposed to type-II Cepheids, low-mass stars with a very different evolutionary history) in a binary system is needed in order to determine which is correct. The accuracy of previous efforts to establish a dynamical Cepheid mass from Galactic single-lined non-eclipsing binaries was typically about 15-30% (refs 6, 7), which is not good enough to resolve the mass discrepancy problem. In spite of many observational efforts, no firm detection of a classical Cepheid in an eclipsing double-lined binary has hitherto been reported. Here we report the discovery of a classical Cepheid in a well detached, double-lined eclipsing binary in the Large Magellanic Cloud. We determine the mass to a precision of 1% and show that it agrees with its pulsation mass, providing strong evidence that pulsation theory correctly and precisely predicts the masses of classical Cepheids. PMID:21107425

Pietrzy?ski, G; Thompson, I B; Gieren, W; Graczyk, D; Bono, G; Udalski, A; Soszy?ski, I; Minniti, D; Pilecki, B

2010-11-25

7

Cataclysmic variables below the period gap: mass determinations of 14 eclipsing systems  

Microsoft Academic Search

We present high-speed, three-colour photometry of the eclipsing cataclysmic variables CTCV J1300-3052, CTCV J2354-4700 and SDSS J115207.00+404947.8. These systems have orbital periods of 128.07, 94.39 and 97.52 min, respectively, placing all three systems below the observed 'period gap' for cataclysmic variables. For each system we determine the system parameters by fitting a parametrized model to the observed eclipse light curve

C. D. J. Savoury; S. P. Littlefair; V. S. Dhillon; T. R. Marsh; B. T. Gänsicke; C. M. Copperwheat; P. Kerry; R. D. G. Hickman; S. G. Parsons

2011-01-01

8

Newton's law of motion for variable mass systems applied to capillarity  

Microsoft Academic Search

The standard Newton's equation of motion for variable masses is set up and solved to describe the time-dependent rise of a liquid in a capillary tube. The findings in the nonviscous case are also supported by quantitative estimates of the potential energy changes suffered by the interfacial films. The theoretical oscillations in the viscous case are confirmed experimentally for tubes

V. J. Menon; D. C. Agrawal

1987-01-01

9

Accumulation variability and mass budgets of the Lambert GlacierAmery Ice Shelf system, East Antarctica, at high elevations  

E-print Network

Accumulation variability and mass budgets of the Lambert Glacier­Amery Ice Shelf system, East, China E-mail: jhwen@sh163a.sta.net.cn 2 Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210-1002, USA 3 Polar Research Institute of China, Shanghai 200129, China 4

Huybrechts, Philippe

10

Rapid X-Ray Variability of Neutron Stars in Low-Mass Binary Systems  

E-print Network

The dramatic discovery with the Rossi X-Ray Timing Explorer satellite of remarkably coherent $\\sim$300--1200 Hz oscillations in the X-ray brightness of some sixteen neutron stars in low-mass binary systems has spurred theoretical modeling of these oscillations and investigation of their implications for the neutron stars and accretion flows in these systems. High-frequency oscillations are observed both during thermonuclear X-ray bursts and during intervals of accretion-powered emission and appear to be a characteristic feature of disk-accreting neutron stars with weak magnetic fields. In this review we focus on the high-frequency quasi-periodic oscillations (QPOs) seen in the accretion-powered emission. We first summarize the key properties of these kilohertz QPOs and then describe briefly the models that have been proposed to explain them. The existing evidence strongly favors beat-frequency models. We mention several of the difficulties encountered in applying the magnetospheric beat-frequency model to the kilohertz QPOs. The most fully developed and successful model is the sonic-point beat-frequency model. We describe the work on this model in some detail. We then discuss observations that could help to distinguish between models. We conclude by noting some of the ways in which study of the kilohertz QPOs may advance our understanding of dense matter and strong gravitational fields.

Frederick K. Lamb; M. Coleman Miller; Dimitrios Psaltis

1998-02-07

11

DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XIII. DZ PISCIUM WITH INTRINSIC LIGHT VARIABILITY  

SciTech Connect

New multi-color photometry for the eclipsing binary DZ Psc was performed in 2011 and 2012 using the 85 cm telescope at the Xinglong Station of the National Astronomical Observatories of China. Using the updated Wilson-Devinney (W-D) code, we deduced two sets of photometric solutions. The overcontact degree is f = 89.7({+-} 1.0)%, identifying DZ Psc as a deep, low mass ratio overcontact binary. The asymmetric light curves (i.e., LC{sub 2} in 2012) were modeled by a hot spot on the primary star. Based on all of the available light minimum times, we discovered that the orbital period of DZ Psc may be undergoing a secular period increase with a cyclic variation. The modulated period and semi-amplitude of this oscillation are P{sub mod} = 11.89({+-} 0.19) yr and A = 0.0064({+-} 0.0006) days, which may be possibly attributed to either cyclic magnetic activity or light-time effect due to the third body. The long-term period increases at a rate of dP/dt=+7.43({+-}0.17) Multiplication-Sign 10{sup -7} days yr{sup -1}, which may be interpreted as conserved mass transfer from the less massive component to the more massive one. With mass transferring, DZ Psc will finally merge into a rapid-rotation single star when J{sub spin}/J{sub orb} > 1/3.

Yang, Y.-G.; Dai, H.-F. [School of Physics and Electronic Information, Huaibei Normal University, 235000 Huaibei, Anhui Province (China); Qian, S.-B. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming (China); Zhang, L.-Y. [Department of Physics, College of Science, Guizhou University, 550025 Guiyang (China); Soonthornthum, B., E-mail: yygcn@163.com, E-mail: qsb@ynao.ac.cn [National Astronomical Research Institute of Thailand/Ministry of Science and Technology, Bangkok (Thailand)

2013-08-01

12

Evolution of rotationally and tidally distorted low-mass, close binary systems - Implications for the minimum orbital period of cataclysmic variables  

Microsoft Academic Search

A (1 + 0.4) solar mass close binary system consisting of a compact primary and a red dwarf secondary has been evolved numerically. Such a binary system should effectively model cataclysmic variables for which a minimum orbital period cutoff of about 81 minutes has been observed. The influence of gravitational radiation losses which drive Roche lobe overflow has been studied,

L. A. Nelson; W. Y. Chau; A. Rosenblum

1985-01-01

13

Evolution of rotationally and tidally distorted low-mass, close binary systems - implications for the minimum orbital period of cataclysmic variables  

Microsoft Academic Search

A (1 + 0.4) solar mass close binary system consisting of a compact primary and a red dwarf secondary has been evolved numerically. Such a binary system should effectively model cataclysmic variables for which a minimum orbital period cutoff of about 81 minutes has been observed. The influence of gravitational radiation losses which drive Roche lobe overflow has been studied,

L. A. Nelson; W. Y. Chau; A. Rosenblum

1985-01-01

14

Pulsational Mass Loss in Luminous Blue Variables  

NASA Astrophysics Data System (ADS)

Luminous Blue Variables are evolved stars which experience periods of enhanced mass loss and outbursts. During these outbursts, the star stays at constant luminosity, but appears to become cooler. The S Doradus type variability, unlike the more extreme eruptions seen in ? Car, occur on timescales of years to decades. The origin of the variability is still not understood, nor is the connection to extreme objects such as ? Car. In this work, we examine hydrodynamic models of radial pulsation including time-dependent convection in massive stars, looking for the conditions necessary to trigger S Doradus type variability.

Lovekin, C. C.; Guzik, J. A.

2012-12-01

15

Black hole mass and variability in quasars  

E-print Network

We report on a study that finds a positive correlation between black hole mass and variability amplitude in quasars. Roughly 100 quasars at zBlack hole masses were estimated with the virial method using the broad Hbeta line, and variability was characterized from the QUEST1 light curves. The correlation between black hole mass and variability amplitude is significant at the 99% level or better and does not appear to be caused by obvious selection effects inherent to flux-limited samples. It is most evident for rest frame time lags of the order a few months up to the QUEST1 maximum temporal resolution of about 2 years. The correlation between black hole mass and variability amplitude means that the more massive black holes have larger percentage flux variations. Over 2-3 orders of magnitude in black hole mass, the amplitude increases by approximately 0.2 mag. A likely explanation for the correlation is that the more massive black holes are starving and produce larger flux variations because they do not have a steady inflow of gaseous fuel. Assuming that the variability arises from changes in the accretion rate Li & Cao [8] show that flux variations similar to those observed are expected as a consequence of the more massive black holes having cooler accretion disks.

M. Wold; M. S. Brotherton; Z. Shang

2008-07-24

16

Evolution of rotationally and tidally distorted low-mass, close binary systems - Implications for the minimum orbital period of cataclysmic variables  

NASA Technical Reports Server (NTRS)

A (1 + 0.4) solar mass close binary system consisting of a compact primary and a red dwarf secondary has been evolved numerically. Such a binary system should effectively model cataclysmic variables for which a minimum orbital period cutoff of about 81 minutes has been observed. The influence of gravitational radiation losses which drive Roche lobe overflow has been studied, and the effects of rotational and tidal distortion have also been incorporated in the calculation. The evolution of the He-3 abundance, which has been suggested as a possible explanation for the upper limit of the apparent orbital period gap exhibited by cataclysmic variables, is also considered. It is found that both the distortional effects and the He-3 chemical profile can play an important role in determining the subsequent evolution of these systems. Specifically, when distortion is included, the theoretical minimum orbital period is increased by about 10 percent, yielding better agreement with observations.

Nelson, L. A.; Chau, W. Y.; Rosenblum, A.

1985-01-01

17

Variable contour securing system  

NASA Technical Reports Server (NTRS)

A variable contour securing system has a retaining structure for a member whose surface contains a variable contour. The retaining mechanism includes a spaced array of adjustable spindles mounted on a housing. Each spindle has a base member support cup at one end. A vacuum source is applied to the cups for seating the member adjacent to the cups. A locking mechanism sets the spindles in a predetermined position once the member has been secured to the spindle support cups.

Zebus, P. P.; Packer, P. N.; Haynie, C. C. (inventors)

1978-01-01

18

Comprehensive theory of the Deans' switch as a variable flow splitter: fluid mechanics, mass balance, and system behavior.  

PubMed

The Deans' switch is an effluent switching device based on controlling flows of carrier gas instead of mechanical valves in the analytical flow path. This technique offers high inertness and a wear-free operation. Recently new monolithic microfluidic devices have become available. In these devices the whole flow system is integrated into a small metal device with low thermal mass and leak-tight connections. In contrast to a mechanical valve-based system, a flow-controlled system is more difficult to calculate. Usually the Deans' switch is used to switch one inlet to one of two outlets, by means of two auxiliary flows. However, the Deans' switch can also be used to deliver the GC effluent with a specific split ratio to both outlets. The calculation of the split ratio of the inlet flow to the two outlets is challenging because of the asymmetries of the flow resistances. This is especially the case, if one of the outlets is a vacuum device, such as a mass spectrometer, and the other an atmospheric detector, e.g. a flame ionization detector (FID) or an olfactory (sniffing) port. The capillary flows in gas chromatography are calculated with the Hagen-Poiseuille equation of the laminar, isothermal and compressible flow in circular tubes. The flow resistances in the new microfluidic devices have to be calculated with the corresponding equation for rectangular cross-section microchannels. The Hagen-Poiseuille equation underestimates the flow to a vacuum outlet. A corrected equation originating from the theory of rarefied flows is presented. The calculation of pressures and flows of a Deans' switch based chromatographic system is done by the solution of mass balances. A specific challenge is the consideration of the antidiffusion resistor between the two auxiliary gas lines of the Deans' switch. A full solution for the calculation of the Deans' switch including this restrictor is presented. Results from validation measurements are in good accordance with the developed theories. A spreadsheet-based flow calculator is part of the Supporting Information. PMID:23980824

Boeker, Peter; Leppert, Jan; Mysliwietz, Bodo; Lammers, Peter Schulze

2013-10-01

19

Jets impactants masse volumique variable J. DUBOISa,  

E-print Network

'hélium impactant est ainsi analysé par la méthode BOS (Background Oriented Schlieren) qui permet de mesurer le (Background Oriented Schlieren) when the jet is impacting a sphere placed in the nearfield. M o t s clefs: Jet impactant, masse volumique variable, BOS (Background Oriented Schlieren), limites d'inflammabilité 1

Boyer, Edmond

20

THE ORIGIN OF VARIABILITY OF THE INTERMEDIATE-MASS BLACK-HOLE ULX SYSTEM HLX-1 IN ESO 243-49  

SciTech Connect

The ultra-luminous (L{sub X} {approx}< 10{sup 42} erg s{sup -1}) intermediate-mass black-hole (IMBH) system HLX-1 in the ESO 243-49 galaxy exhibits variability with a possible recurrence time of a few hundred days. Finding the origin of this variability would constrain the still largely unknown properties of this extraordinary object. Since it exhibits a hardness-intensity behavior characteristic of black-hole X-ray transients, we have analyzed the variability of HLX-1 in the framework of the disk instability model that explains outbursts of such systems. We find that the long-term variability of HLX-1 is unlikely to be explained by a model in which outbursts are triggered by thermal-viscous instabilities in an accretion disk. Possible alternatives include the instability in a radiation-pressure-dominated disk but we argue that a more likely explanation is a modulated mass transfer due to tidal stripping of a star in an eccentric orbit around the IMBH. We consider an evolutionary scenario leading to the creation of such a system and estimate the probability of its observation. We conclude, using a simplified dynamical model of the post-collapse cluster, that no more than 1/100 to 1/10 of M{sub .} {approx}< 10{sup 4} M{sub sun} IMBHs-formed by runaway stellar mergers in the dense collapsed cores of young clusters-could have a few x1 M{sub sun} main-sequence star evolve to an asymptotic giant branch on an orbit eccentric enough for mass transfer at periapse, while avoiding collisional destruction or being scattered into the IMBH by two-body encounters. The finite but low probability of this configuration is consistent with the uniqueness of HLX-1. We note, however, that the actual response of a standard accretion disk to bursts of mass transfer may be too slow to explain the observations unless the orbit is close to parabolic (and hence even rarer). Also, increased heating, presumably linked to the highly time-dependent gravitational potential, could shorten the relevant timescales.

Lasota, J.-P. [Institut d'Astrophysique de Paris, UMR 7095 CNRS, UPMC Univ Paris 06, 98bis Boulevard Arago, 75014 Paris (France); Alexander, T. [Department of Particle Physics and Astrophysics, Faculty of Physics, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100 (Israel); Dubus, G. [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041 (France); Barret, D.; Godet, O.; Webb, N. A. [Universite de Toulouse, Universite Paul Sabatier, Observatoire Midi-Pyrenees, Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse (France); Farrell, S. A. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Gehrels, N., E-mail: lasota@iap.fr [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2011-07-10

21

Climate warming increases Greenland Ice Sheet surface mass balance variability  

NASA Astrophysics Data System (ADS)

We analyze Greenland Ice Sheet (GIS) surface mass balance (SMB) trends generated by the Community Earth System Model for the time period 1850-2100. In addition to the expected decrease in the mean SMB, our analysis reveals a significant secular increase in temporal, integrated SMB variability. The largest variability increase occurs during the 21st century, and arises primarily from growth of the GIS ablation zone (i.e., a decrease in the accumulation area ratio, AAR) in conjunction with a high ratio of ablation-zone to accumulation-zone specific SMB variability. A secondary cause of the overall variability increase is a rise in specific SMB variability itself in both the accumulation and ablation zones, due to increased accumulation variability and lengthened melt seasons. Simple sensitivity experiments indicate that neither mechanism (decrease in the AAR, and increased specific SMB variability) in isolation is capable of causing the overall increase in integrated SMB variability. However, by exposing more of the ice sheet to high-variability ablation, the decrease in the AAR is about twice as effective as increased specific SMB variability in causing the overall variability increase. Ablation-zone SMB variability is driven largely by variability in summertime melting which is in turn regulated by variability in summertime surface energy fluxes. Broader climate processes that regulate these fluxes will therefore exert increasing control on GIS SMB variability in the future. This future increase in SMB variability can be expected to impact GIS-sourced freshwater fluxes and GIS ice dynamic variability, and may also make it more difficult to diagnose future secular trends in GIS volume.

Fyke, J. G.; Vizcaino, M.; Lipscomb, W. H.; Sacks, W.

2013-12-01

22

Ultra High Mass Range Mass Spectrometer System  

DOEpatents

Applicant's present invention comprises mass spectrometer systems that operate in a mass range from 1 to 10.sup.16 DA. The mass spectrometer system comprising an inlet system comprising an aerodynamic lens system, a reverse jet being a gas flux generated in an annulus moving in a reverse direction and a multipole ion guide; a digital ion trap; and a thermal vaporization/ionization detector system. Applicant's present invention further comprises a quadrupole mass spectrometer system comprising an inlet system having a quadrupole mass filter and a thermal vaporization/ionization detector system. Applicant's present invention further comprises an inlet system for use with a mass spectrometer system, a method for slowing energetic particles using an inlet system. Applicant's present invention also comprises a detector device and a method for detecting high mass charged particles.

Reilly, Peter T. A. [Knoxville, TN

2005-12-06

23

Mode Selection Techniques in Variable Mass Flexible Body Modeling  

NASA Technical Reports Server (NTRS)

In developing a flexible body spacecraft simulation for the Launch Abort System of the Orion vehicle, when a rapid mass depletion takes place, the dynamics problem with time varying eigenmodes had to be addressed. Three different techniques were implemented, with different trade-offs made between performance and fidelity. A number of technical issues had to be solved in the process. This paper covers the background of the variable mass flexibility problem, the three approaches to simulating it, and the technical issues that were solved in formulating and implementing them.

Quiocho, Leslie J.; Ghosh, Tushar K.; Frenkel, David; Huynh, An

2010-01-01

24

Variable Flow Chilled Water Systems  

E-print Network

Today, substantial savings can be achieved by converting constant flow-rate chilled water systems to variable flow-rate systems. This conversion is best suited for large, central plant chilled water systems where two or more chillers are utilized...

Baldwin, D. A.

25

Modeling and Simulation of Variable Mass, Flexible Structures  

NASA Technical Reports Server (NTRS)

The advent of the new Ares I launch vehicle has highlighted the need for advanced dynamic analysis tools for variable mass, flexible structures. This system is composed of interconnected flexible stages or components undergoing rapid mass depletion through the consumption of solid or liquid propellant. In addition to large rigid body configuration changes, the system simultaneously experiences elastic deformations. In most applications, the elastic deformations are compatible with linear strain-displacement relationships and are typically modeled using the assumed modes technique. The deformation of the system is approximated through the linear combination of the products of spatial shape functions and generalized time coordinates. Spatial shape functions are traditionally composed of normal mode shapes of the system or even constraint modes and static deformations derived from finite element models of the system. Equations of motion for systems undergoing coupled large rigid body motion and elastic deformation have previously been derived through a number of techniques [1]. However, in these derivations, the mode shapes or spatial shape functions of the system components were considered constant. But with the Ares I vehicle, the structural characteristics of the system are changing with the mass of the system. Previous approaches to solving this problem involve periodic updates to the spatial shape functions or interpolation between shape functions based on system mass or elapsed mission time. These solutions often introduce misleading or even unstable numerical transients into the system. Plus, interpolation on a shape function is not intuitive. This paper presents an approach in which the shape functions are held constant and operate on the changing mass and stiffness matrices of the vehicle components. Each vehicle stage or component finite element model is broken into dry structure and propellant models. A library of propellant models is used to describe the distribution of mass in the fuel tank or Solid Rocket Booster (SRB) case for various propellant levels. Based on the mass consumed by the liquid engine or SRB, the appropriate propellant model is coupled with the dry structure model for the stage. Then using vehicle configuration data, the integrated vehicle model is assembled and operated on by the constant system shape functions. The system mode shapes and frequencies can then be computed from the resulting generalized mass and stiffness matrices for that mass configuration. The rigid body mass properties of the vehicle are derived from the integrated vehicle model. The coupling terms between the vehicle rigid body motion and elastic deformation are also updated from the constant system shape functions and the integrated vehicle model. This approach was first used to analyze variable mass spinning beams and then prototyped into a generic dynamics simulation engine. The resulting code was tested against Crew Launch Vehicle (CLV-)class problems worked in the TREETOPS simulation package and by Wilson [2]. The Ares I System Integration Laboratory (SIL) is currently being developed at the Marshall Space Flight Center (MSFC) to test vehicle avionics hardware and software in a hardware-in-the-loop (HWIL) environment and certify that the integrated system is prepared for flight. The Ares I SIL utilizes the Ares Real-Time Environment for Modeling, Integration, and Simulation (ARTEMIS) tool to simulate the launch vehicle and stimulate avionics hardware. Due to the presence of vehicle control system filters and the thrust oscillation suppression system, which are tuned to the structural characteristics of the vehicle, ARTEMIS must incorporate accurate structural models of the Ares I launch vehicle. The ARTEMIS core dynamics simulation models the highly coupled nature of the vehicle flexible body dynamics, propellant slosh, and vehicle nozzle inertia effects combined with mass and flexible body properties that vary significant with time during the flight. All forces that act on the vehicle during flight must be simulated,

Tobbe, Patrick A.; Matras, Alex L.; Wilson, Heath E.

2009-01-01

26

Variability in properties of Salado Mass Concrete  

SciTech Connect

Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft{sup 3} to 5.0 yd{sup 3}, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties.

Wakeley, L.D.; Harrington, P.T. [US Army Engineer Waterways Experiment Station, Vicksburg, MS (United States); Hansen, F.D. [Sandia National Labs., Albuquerque, NM (United States)

1995-08-01

27

Variable buoyancy system metric  

E-print Network

Over the past 20 years, underwater vehicle technology has undergone drastic improvements, and vehicles are quickly gaining popularity as a tool for numerous oceanographic tasks. Systems used on the vehicle to alter buoyancy, ...

Jensen, Harold Franklin

2009-01-01

28

Variable mass unites Newtonian and GR gravity  

NASA Astrophysics Data System (ADS)

Newton's law of universal gravitation assumes constant mass. We have since learned that mass changes with speed (by SR) and also in the presence of a gravitational potential. This study examines the consequences of introducing these changes of mass into Newton's law. With 1/? ? (1+GM/rc^2), it follows that a rest mass, m0 in gravity-free space, increases to m^*=? m_0/? =m_0/?^2 under free fall. This increase of mass results in a real contraction of the metric of length and time intervals: l^*=?^2 l and t^*=?^2 t. This scalar modification of Newtonian gravity easily and correctly accounts for the classical tests of GR, including starlight deflection, time delay for light transiting a gravitational region, and the precession rate of the perihelion of Mercury. It confirms the GR concept of non-Euclidean geometry in gravitational space, but the concept of black holes is not supported. Newtonian gravity is found to agree with experiment, requiring only that mass be correctly portrayed.

Collins, Russell

2000-03-01

29

Characterization and modeling of a novel electro-hydraulic variable two-terminal mass device  

NASA Astrophysics Data System (ADS)

Much effort has been devoted to developing variable stiffness and variable damping devices for semi-active structural vibration control. However, little research has been done for variable inertial mass mainly caused by the mechanical terminal limit of the mass component. Based on the two-terminal mass scheme, we propose an electro-hydraulic approach to realizing a novel device with variable two-terminal mass. In this study, the flywheel that is traditionally handled by one physical terminal is manipulated by two terminals of a hydraulic cylinder-control-motor system. The transmission ratio of the system is adjusted using an electro-hydraulic proportional valve. Through modeling the ideal dynamic behavior, it is confirmed that the equivalent inertial mass between two terminals of the component can be made variable. To further understand its mechanical characteristics, a prototype device is developed and tested on a test rig. Triangular and sinusoidal excitation signals are employed respectively to identify the model parameters. The results show that the proposed model can describe the dynamic characteristics of the variable two-terminal mass device well. The proposed design and modeling schemes pave the way towards the semi-active variable inertial mass control of vibration systems.

Li, C.; Liang, M.

2012-02-01

30

A variable acceleration calibration system  

NASA Astrophysics Data System (ADS)

A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of uncertainty analysis. Three types of uncertainty are indentified for the systems and are attributed to prediction error, calibration error and pure error. Angular velocity uncertainty is shown to be the largest indentified source of prediction error. The calibration uncertainties using a production variable acceleration based system are shown to be potentially equivalent to current methods. The production quality system can be realized using lighter materials and a more precise instrumentation. Further research is needed to account for balance deflection, forcing effects due to vibration, and large tare loads. A gyroscope measurement technique is shown to be capable of resolving the balance deflection angle calculation. Long term research objectives include a demonstration of a six degree of freedom calibration, and a large capacity balance calibration.

Johnson, Thomas H.

2011-12-01

31

The Ages, Masses, Evolution and Kinematics of Mira variable  

E-print Network

Evidence on the ages and masses of Mira variables is reviewed. Period increases with increasing initial mass. Miras of logP about 3.0 have initial masses of near 4 solar masses. It is suggestd that the apparent gap in the LMC PL relation at about this period may be due to the onset of hot bottom burning and that this adds about 15 to 20 percent to the stellar energy production. Shorter period HBB stars are probably overtone pulsators. T Lep may be an example of cool bottom processing.

Michael Feast

2008-12-01

32

Theories of Variable Mass Particles and Low Energy Nuclear Phenomena  

NASA Astrophysics Data System (ADS)

Variable particle masses have sometimes been invoked to explain observed anomalies in low energy nuclear reactions (LENR). Such behavior has never been observed directly, and is not considered possible in theoretical nuclear physics. Nevertheless, there are covariant off-mass-shell theories of relativistic particle dynamics, based on works by Fock, Stueckelberg, Feynman, Greenberger, Horwitz, and others. We review some of these and we also consider virtual particles that arise in conventional Feynman diagrams in relativistic field theories. Effective Lagrangian models incorporating variable mass particle theories might be useful in describing anomalous nuclear reactions by combining mass shifts together with resonant tunneling and other effects. A detailed model for resonant fusion in a deuterium molecule with off-shell deuterons and electrons is presented as an example. Experimental means of observing such off-shell behavior directly, if it exists, is proposed and described. Brief explanations for elemental transmutation and formation of micro-craters are also given, and an alternative mechanism for the mass shift in the Widom-Larsen theory is presented. If variable mass theories were to find experimental support from LENR, then they would undoubtedly have important implications for the foundations of quantum mechanics, and practical applications may arise.

Davidson, Mark

2014-02-01

33

Modes, masses, metallicities, and magnitudes of RR Lyrae variables  

SciTech Connect

The author reviews past and recent developments in the study of RR Lyrae variables. He provides supporting evidence for a large helium content but remains uncertain as to their masses and luminosities. Time dependent convection is offered as a probable explanation for the double mode pulsations of these stars. 25 refs., 8 figs., 3 tabs.

Cox, A.N.

1987-07-01

34

Variable frequency microwave furnace system  

DOEpatents

A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN)

1994-01-01

35

Near-infrared Variability in the 2MASS Calibration Fields: A Search for Planetary Transit Candidates  

NASA Technical Reports Server (NTRS)

The Two Micron All Sky Survey (2MASS) photometric calibration observations cover approximately 6 square degrees on the sky in 35 'calibration fields,' each sampled in nominal photometric conditions between 562 and 3692 times during the 4 years of the 2MASS mission. We compile a catalog of variables from the calibration observations to search for M dwarfs transited by extrasolar planets. We present our methods for measuring periodic and nonperiodic flux variability. From 7554 sources with apparent K(sub s) magnitudes between 5.6 and 16.1, we identify 247 variables, including extragalactic variables and 23 periodic variables. We have discovered three M dwarf eclipsing systems, including two candidates for transiting extrasolar planets.

Plavchan, Peter; Jura, M.; Kirkpatrick, J. Davy; Cutri, Roc M.; Gallagher, S. C.

2008-01-01

36

Spacecraft telecommunications system mass estimates  

NASA Technical Reports Server (NTRS)

Mass is the most important limiting parameter for present-day planetary spacecraft design, In fact, the entire design can be characterized by mass. The more efficient the design of the spacecraft, the less mass will be required. The communications system is an essential and integral part of planetary spacecraft. A study is presented of the mass attributable to the communications system for spacecraft designs used in recent missions in an attempt to help guide future design considerations and research and development efforts. The basic approach is to examine the spacecraft by subsystem and allocate a portion of each subsystem to telecommunications. Conceptually, this is to divide the spacecraft into two parts, telecommunications and nontelecommunications. In this way, it is clear what the mass attributable to the communications system is. The percentage of mass is calculated using the actual masses of the spacecraft parts, except in the case of CRAF. In that case, estimated masses are used since the spacecraft was not yet built. The results show that the portion of the spacecraft attributable to telecommunications is substantial. The mass fraction for Voyager, Galileo, and CRAF (Mariner Mark 2) is 34, 19, and 18 percent, respectively. The large reduction of telecommunications mass from Voyager to Galileo is mainly due to the use of a deployable antenna instead of the solid antenna on Voyager.

Yuen, J. H.; Sakamoto, L. L.

1988-01-01

37

Photometric variability of a young, low-mass brown dwarf  

E-print Network

We report differential I-band and J-band photometry of S Ori 45, a cool (M8.5), young (1-8 Myr) brown dwarf of the sigma Orionis cluster with a likely mass estimated at around 20 times the mass of Jupiter. We detect variability (amplitudes ranging from 34 to 81 mmag) and observe a modulation at a period of 2.5-3.6 h in both optical and near-infrared light curves. The most recent optical data set, however, presents a modulation at the very short period of 46.4+/-1.5 min, which remains a mystery. The origin of the 2.5-3.6 h modulation is analized in terms of various scenarios: inhomogeneous features (dust clouds or magnetically induced dark spots) co-rotating with the object's surface, and presence of an unseen very low-mass companion that is steadily transferring mass to the primary. Because of the very young age of the object and its persistent strong Halpha emission, the possible presence of an accreting disk is also discussed. If the period of a few hours is related to rotation, our results suggest that sigma Orionis low-mass brown dwarfs are rotating faster than more massive cluster brown dwarfs at a rate consistent with their theoretically inferred masses and radii, implying that all of these objects have undergone similar angular momentum evolution.

M. R. Zapatero Osorio; J. A. Caballero; V. J. S. Bejar; R. Rebolo

2003-06-19

38

Variable structure systems with sliding modes  

Microsoft Academic Search

Variable structure systems consist of a set of continuous subsystems together with suitable switching logic. Advantageous properties result from changing structures according to this switching logic. Design and analysis for this class of systems are surveyed in this paper.

VADIM I. UTKIN

1977-01-01

39

Validation of GRACE time variable gravity against atmospheric mass variations  

NASA Astrophysics Data System (ADS)

The GRACE gravity satellite mission is designed to deliver maps of the static and time variable Earth's gravity field with an unprecedented accuracy. GRACE will resolve temporal variations in gravity at length scales of a few hundred km and larger, and produce a complete global map once every 30 days. In order to Calibrate/Validate (Cal/Val) GRACE data, we must select an area of greater than 2× 10^5 km^2 where the integral of all surface mass changes can be constrained with an accuracy better than 1 cm of water thickness equivalent. As it would be difficult to constrain the hydrology and precipitation signals in a typical region with sufficient accuracy, we Cal/Val GRACE in relatively water-free areas where the atmospheric pressure can be well constrained. We present results of the Cal/Val of GRACE satellite data in the desert of southwestern Egypt. This extremely dry region has several barometers and rain gauges within or nearby. The gravity variation measured by GRACE in the selected area will be the sum of contributions from the GRACE measurement error, the error in removing the atmospheric mass variation using geopotential heights from an ECMWF global circulation model, the fluctuation of water mass in the Nile river and Lake Nasser, aquifer depletion, and sea surface variations in surrounding seas. In general, only the atmospheric mass variation will be significant at the 1 cm level of water thickness equivalent within the Cal/Val area. Simulations indicate that other signals besides the atmosphere should contribute negligibly to the time variable gravity measured by GRACE. To approximate the error in removing atmospheric mass distribution from GRACE data, we calculate the difference between surface pressure from barometer measurements and modeled surface pressure from ECMWF, averaged over periods of GRACE monthly estimates of geoid. We will compare residual differences with the signal measured by GRACE. Further, we will examine errors in the ECMWF numerical model outputs, particularly in the polar regions and over the southern hemisphere where the GCM assimilates very sparse in situ measurements. Atmospheric refractivity structure derived from GPS occultations is very sensitive to geopotential height, and unlike most available atmospheric pressure measurements, occultation data are not assimilated into ECMWF and so are completely independent of the model outputs. We will show preliminary results comparing geopotential heights from SAC-C and CHAMP occultation data with geopotential heights from GCMs.

Velicogna, I.; Wahr, J.; Hajj, G.

2003-04-01

40

Validation of GRACE Time Variable Gravity Against Atmospheric Mass Variations  

NASA Astrophysics Data System (ADS)

GRACE will resolve temporal variations in gravity at length scales of a few hundred km and larger, and produce a complete global map once every 30 days. The data delivered by GRACE will need to be calibrated and validated in order to ensure their quality and reliability. The Calibration/Validation (Cal/Val) phase will validate the data collected during the on-orbit checkout phase and verify the quality of the data for the entire life span of the mission. In order to Cal/Val GRACE data, we must select an area of greater than 2x 105 km^2$ where the integral of all surface mass changes can be constrained with an accuracy better than 1 cm of water thickness equivalent. As it would be difficult to constrain the hydrology and precipitation signals in a typical region with sufficient accuracy, we Cal/Val GRACE in relatively water-free areas where the atmospheric pressure can be well constrained. We present the results of the Cal/Val of GRACE satellite data in the desert of southwestern Egypt. This extremely dry region has several barometers and rain gauges within or nearby. The gravity variation measured by GRACE in the selected area will be the sum of contributions from the GRACE measurement error, the error in removing the atmospheric mass variation using geopotential heights from an ECMWF global circulation model, the fluctuation of water mass in the Nile river and Lake Nasser, aquifer depletion, and sea surface variations in surrounding seas. In general, only the atmospheric mass variation will be significant at the 1 cm level of water thickness equivalent within the Cal/Val area. Simulations indicate that the other signals besides the atmosphere should contribute negligibly to the time variable gravity measured by GRACE.To approximate the error in removing atmospheric mass distribution from GRACE data, we calculate the difference between surface pressure from barometer measurements and modeled surface pressure from ECMWF, averaged over periods of GRACE monthly estimates of geoid. We will compare residual differences with the signal measured by GRACE. If the two signals are significantly different we will investigate if the fluctuation of water mass in the area can be responsible for the observed discrepancy.

Velicogna, I.; Wahr, J.

2002-12-01

41

Inseparability criterion for continuous variable systems  

E-print Network

An inseparability criterion based on the total variance of a pair of Einstein-Podolsky-Rosen type operators is proposed for continuous variable systems. The criterion provides a sufficient condition for entanglement of any two-party continuous variable states. Furthermore, for all the Gaussian states, this criterion turns out to be a necessary and sufficient condition for inseparability.

Lu-Ming Duan; G. Giedke; J. I. Cirac; P. Zoller

2000-03-24

42

System and Variability in Interlanguage Syntax.  

ERIC Educational Resources Information Center

Reviews the notions of system and variability as applied to interlanguages, especially with respect to variability in the syntax of second language learners. Summarizes the findings of Huebner with respect to referentiality and then examines some new data collected 20 months after the end of the initial study. (SED)

Huebner, Thom

1985-01-01

43

Model atmospheres with periodic shocks. [pulsations and mass loss in variable stars  

NASA Technical Reports Server (NTRS)

The pulsation of a long-period variable star generates shock waves which dramatically affect the structure of the star's atmosphere and produce conditions that lead to rapid mass loss. Numerical modeling of atmospheres with periodic shocks is being pursued to study the processes involved and the evolutionary consequences for the stars. It is characteristic of these complex dynamical systems that most effects result from the interaction of various time-dependent processes.

Bowen, G. H.

1989-01-01

44

Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study  

SciTech Connect

This scoping study focuses on the policy issues inherent in the claims made by some Smart Grid proponents that the demand response potential of mass market customers which is enabled by widespread implementation of Advanced Metering Infrastructure (AMI) through the Smart Grid could be the “silver bullet” for mitigating variable generation integration issues. In terms of approach, we will: identify key issues associated with integrating large amounts of variable generation into the bulk power system; identify demand response opportunities made more readily available to mass market customers through widespread deployment of AMI systems and how they can affect the bulk power system; assess the extent to which these mass market Demand Response (DR) opportunities can mitigate Variable Generation (VG) integration issues in the near-term and what electricity market structures and regulatory practices could be changed to further expand the ability for DR to mitigate VG integration issues over the long term; and provide a qualitative comparison of DR and other approaches to mitigate VG integration issues.

Cappers, Peter; Mills, Andrew; Goldman, Charles; Wiser, Ryan; Eto, Joseph H.

2011-09-10

45

Optical Mass Memory System Specification  

NASA Technical Reports Server (NTRS)

Specifications given for computer controlled optical mass memory system that stores and retrieves data from silver halide fiches 148-mmsquare and 7 mils (0.18mm) thick at user bit density of 30 Mbit/in. 2 (4.7 Mbit/cm2) with uncorrectable bit-error rate of 10 to negative 9th power or less. Allows for expansion to 10 the 15th power bit capacity.

1985-01-01

46

Causes of temporal variability of lead in domestic plumbing systems.  

PubMed

Sources of lead in drinking water are primarily lead pipe, lead/tin solder, and brass fixture materials.Lead levels in the water depend upon many solubility factors, such as pH, concentrations of substances such as inorganic carbonate, orthophosphate, chlorine, and silicate, the temperature, the nature of the pipe surface, etc. Physical factors, time, and chemical mass transfer are significant in governing lead levels in nonequilibrium systems. The diameter and length of lead pipe is extremely important, as well as the age and chemical history of the solder and brass fixtures. Analytical variability is not particularly significant relative to between-site and within-site variability. Knowledge of temporal variability at each site is necessary to define a statistically valid monitoring program. An analysis of published data covering repetitive measurements at a given site show that the variability of lead concentration at each site tends to be characterized by the frequent occurrence of 'spikes'. Variability expressed as approximate relative standard deviations tends to be of about 50 to 75% in untreated water, regardless of the mean lead concentration. The distributions are frequently nonnormal for small numbers of samples. Monitoring programs must incorporate controls for the causes of the within-site and between-site variability into their sampling design. The determination of necessary sampling frequency, sample number, and sample volume must be made with consideration of the system variability, or the results will be unrepresentative and irreproducible. PMID:24243429

Schock, M R

1990-07-01

47

Fast Simulation of Mass-Spring Systems Tiantian Liu  

E-print Network

.g., games) and slows production work flows in off-line settings (e.g., film and visual effects spring directions as auxiliary unknown variables. The system is globally linear in the node positions: Time integration, implicit Euler method, mass-spring systems. Links: DL PDF VIDEO WEB 1 Introduction

Plotkin, Joshua B.

48

Interesting examples of supervised continuous variable systems  

NASA Technical Reports Server (NTRS)

The authors analyze two simple deterministic flow models for multiple buffer servers which are examples of the supervision of continuous variable systems by a discrete controller. These systems exhibit what may be regarded as the two extremes of complexity of the closed loop behavior: one is eventually periodic, the other is chaotic. The first example exhibits chaotic behavior that could be characterized statistically. The dual system, the switched server system, exhibits very predictable behavior, which is modeled by a finite state automaton. This research has application to multimodal discrete time systems where the controller can choose from a set of transition maps to implement.

Chase, Christopher; Serrano, Joe; Ramadge, Peter

1990-01-01

49

A Variable Length Tentacle Manipulator Control System  

Microsoft Academic Search

The control problem of a class of tentacle arm, with variable length, that can achieve any position and orientation in 3D space and can increase the length in order to get a better control in the constraint operator space is presented. First, the dynamic model of the system is inferred. In order to avoid the difficulties generated by the complexity

Mircea Ivanescu; Nirvana Popescu; Decebal Popescu

2005-01-01

50

Quantifying decoherence in continuous variable systems  

Microsoft Academic Search

We present a detailed report on the decoherence of quantum states of continuous variable systems under the action of a quantum optical master equation resulting from the interaction with general Gaussian uncorrelated environments. The rate of decoherence is quantified by relating it to the decay rates of various, complementary measures of the quantum nature of a state, such as the

A Serafini; M G A Paris; F. Illuminati; S. De Siena

2005-01-01

51

Designing and commissioning variable flow hydronic systems  

Microsoft Academic Search

Direct return variable flow hydronic systems (VFHS) must (in this author's opinion) be designed to be self-balancing. However, in practice, many design engineers will use customary pipe sizing routines, piping detail drawings and specifications that apply to more familiar constant flow systems. Substituting a two-way valve in place of a three-way valve and bypass pipe, while retaining the balancing valve

1993-01-01

52

Variable stars in the VVV globular clusters. I. 2MASS-GC02 and Terzan10  

E-print Network

The VISTA Variables in the Via Lactea (VVV) ESO Public Survey is opening a new window to study the inner Galactic globular clusters using their variable stars. These globular clusters have been neglected in the past due to the difficulties caused by the presence of an elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RRLyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the interrogations brought by the intriguing Oosterhoff dichotomy in the Galactic globular cluster system. In a series of papers we plan to explore the variable stars in the globular clusters falling inside the field of the VVV survey. In this first paper we search and study the variables present in two highly-reddened, moderately metal-poor, faint, inner Galactic globular clusters: 2MASS-GC02 and Terzan10. We report the discovery of sizable populations of RR ...

Alonso-García, Javier; Catelan, Márcio; Ramos, Rodrigo Contreras; Gran, Felipe; Amigo, Pía; Leyton, Paul; Minniti, Dante

2014-01-01

53

Estimates of AGN Black Hole Mass and Minimum Variability Timescale  

Microsoft Academic Search

Black hole mass is one of the fundamental physical parameters of active galactic nuclei (AGNs), for which many methods of estimation have been proposed. One set of methods assumes that the broad-line region (BLR) is gravitationally bound by the central black hole potential, so the black hole mass can be estimated from the orbital radius and the Doppler velocity. Another

Guang-Zhong Xie; Luo-En Chen; Huai-Zhen Li; Li-Sheng Mao; Hong Dai; Zhao-Hua Xie; Li Ma; Shu-Bai Zhou

2005-01-01

54

Artificial or variable gravity attained by tether systems  

NASA Technical Reports Server (NTRS)

The simplest orbiting tethered system demands for stability that the mass centers of two end bodies be displaced above and below the position of zero acceleration. Therefore, the contents of the end bodies are subjected necessarily to acceleration fields or artificial gravity whose magnitudes depend on the dimensions and masses of the system. If the length of the tether changes, so do the fields. Even for a fixed tether length, the acceleration field at a location in the system may be somewhat variable unless special means are employed to maintain a constant value. These fundamental properties of a tethered system can be used to advantage if small or variable acceleration fields are desired for experimental or operational reasons. This potential use involves a few expressions from a formulation of tether system dynamics. Some of these formulae were collected for convenient use. Two and three body tethered equilibrium equations are explained. A special application of acceleration field control using a tether system is attainment of near-zero gravity. In this applicaition, even small variations about zero become a critical matter.

Lundquist, C. A.

1986-01-01

55

Preliminary experimental results on studying possibility of variable mass liner (VML) formation  

SciTech Connect

The main objective of the present experiment was to study the formation process and initial stage of acceleration of a variable-mass plasma liner (VML). The method is based on magnetic acceleration of a liner with the mass reduced during such acceleration. The experiment was carried out on February 16 at VNIIEF. This report describes the results of measurements obtained in the experiment and preliminary analysis of the results characterizing operation of the test facility main units: helical EMG; 5-module disk EMG 400 mm in diameter (DEMG); ponderomotive unit (PU) with a cylindric condensed liner and a special tooth-cutoff. The first part of the report presents measurement results obtained on the VNIIEF`s diagnostic equipment that are compared with those obtained by American specialists on their diagnostic equipment. Information submitted by American specialists is included in part 2 of this report. The second part of the report presents preliminary computational-theoretic analysis of the main measured results describing operation of DEMG TL system in the experiment; experimental data are compared with theoretical ones obtained before and after the experiment. But more emphasis is placed on the data preliminary analysis indicating that in the experiment a variable mass liner is formed (VML or plasma bubble).

NONE

1995-12-31

56

Mass loss, long-period variables, and the formation of circumnebular shells  

Microsoft Academic Search

We have found that the rate of mass loss M increases with an increase in the period of pulsation for Mira-type variables. This result suggests that the rate of mass loss is accelerated with time until a maximum value is reached before the ejection of the outer envelope. The matter from the continuous mass loss during the evolution of the

M. Kafatos; A. G. Michalitsanos; M. S. Vardya

1977-01-01

57

Temporal variability of mass transport across Canary Islands Channels  

NASA Astrophysics Data System (ADS)

The equatorward flowing Canary Current (CC) is the main feature of the circulation in the Canary Islands region. The CC flow perturbation by the Canary Islands originate the Canary Eddy Corridor which is the major pathway for long lived eddies in the subtropical North Atlantic (Sangrà et al., 2009, DSR). Therefore the variability of the CC passing through the Canary Archipelago will have both local and regional importance. Past studies on the CC variability trough the Canary Islands point out a clearly seasonal variability (Fraile-Nuez et al, 2010 (JGR); Hernández-Guerra et al, 2002 (DSR)). However those studies where focused on the eastern islands channels missing the variability through the western island channels which are the main source of long lived eddies. In order to fill this gap from November 2012 until September 2013 we conducted trimonthly surveys crossing the whole islands channels using opportunity ships (Naviera Armas Ferries). XBT and XCTD where launched along the cross channels transects. Additionally a closed box circling the Archipelago was performed on October 2013 as part of the cruise RAPROCAN-2013 (IEO) using also XBT and XCTD. Dynamical variables where derived inferring salinity from S(T,p) analytical relationships for the region updated with new XCTD data. High resolution, vertical sections of temperature, potential density, geostrophic velocity and transport where obtained. Our preliminary results suggest that the CC suffer a noticeable acceleration in those islands channels where eddy shedding is more frequent. They also indicate a clearly seasonal variability of the flows passing the islands channels. With this regard we observed significant differences on the obtained seasonal variability with respect the cited past studies on the eastern islands channel (Lanzarote / Fuerteventura - Africa coast). This work was co-funded by Canary Government (TRAMIC project: PROID20100092) and the European Union (FEDER).

Marrero-Díaz, Ángeles; Rodríguez-Santana, Ángel; José Machín, Francisco; García-Weil, Luis; Sangrà, Pablo; Vélez-Belchí, Pedro; Fraile-Nuez, Eugenio

2014-05-01

58

Disentanglement in bipartite continuous-variable systems  

SciTech Connect

Entanglement in bipartite continuous-variable systems is investigated in the presence of partial losses such as those introduced by a realistic quantum communication channel, e.g., by propagation in an optical fiber. We find that entanglement can vanish completely for partial losses, in a situation reminiscent of so-called entanglement sudden death. Even states with extreme squeezing may become separable after propagation in lossy channels. Having in mind the potential applications of such entangled light beams to optical communications, we investigate the conditions under which entanglement can survive for all partial losses. Different loss scenarios are examined, and we derive criteria to test the robustness of entangled states. These criteria are necessary and sufficient for Gaussian states. Our study provides a framework to investigate the robustness of continuous-variable entanglement in more complex multipartite systems.

Barbosa, F. A. S.; Coelho, A. S.; Nussenzveig, P.; Martinelli, M. [Instituto de Fisica, Universidade de Sao Paulo, P.O. Box 66318, 05315-970 Sao Paulo (Brazil); Faria, A. J. de [Instituto de Cie circumflex ncia e Tecnologia, Universidade Federal de Alfenas, 37715-400 Pocos de Caldas, MG (Brazil); Cassemiro, K. N. [Instituto de Fisica, Universidade de Sao Paulo, P.O. Box 66318, 05315-970 Sao Paulo (Brazil); Max Planck Institute for the Science of Light, DE-91058 Erlangen (Germany); Villar, A. S. [Instituto de Fisica, Universidade de Sao Paulo, P.O. Box 66318, 05315-970 Sao Paulo (Brazil); Max Planck Institute for the Science of Light, DE-91058 Erlangen (Germany); Lehrstuhl fuer Optik, Universitaet Erlangen-Nuernberg, DE-91058 Erlangen (Germany)

2011-11-15

59

Dynamically variable spot size laser system  

NASA Technical Reports Server (NTRS)

A Dynamically Variable Spot Size (DVSS) laser system for bonding metal components includes an elongated housing containing a light entry aperture coupled to a laser beam transmission cable and a light exit aperture. A plurality of lenses contained within the housing focus a laser beam from the light entry aperture through the light exit aperture. The lenses may be dynamically adjusted to vary the spot size of the laser. A plurality of interoperable safety devices, including a manually depressible interlock switch, an internal proximity sensor, a remotely operated potentiometer, a remotely activated toggle and a power supply interlock, prevent activation of the laser and DVSS laser system if each safety device does not provide a closed circuit. The remotely operated potentiometer also provides continuous variability in laser energy output.

Gradl, Paul R. (Inventor); Hurst, John F. (Inventor); Middleton, James R. (Inventor)

2012-01-01

60

Mobile Variable Depth Sampling System Design Study  

SciTech Connect

A design study is presented for a mobile, variable depth sampling system (MVDSS) that will support the treatment and immobilization of Hanford LAW and HLW. The sampler can be deployed in a 4-inch tank riser and has a design that is based on requirements identified in the Level 2 Specification (latest revision). The waste feed sequence for the MVDSS is based on Phase 1, Case 3S6 waste feed sequence. Technical information is also presented that supports the design study.

BOGER, R.M.

2000-08-25

61

Finite difference analysis of radiative free convection flow past an impulsively started vertical plate with variable heat and mass flux  

Microsoft Academic Search

A numerical solution of the unsteady radiative free convection flow of an incompressible viscous fluid past an impulsively started vertical plate with variable heat and mass flux is presented here. This type of problem finds application in many technological and engineering fields such as rocket propulsion systems, spacecraft re- entry aerothermodynamics, cosmical flight aerodynamics, plasma physics, glass production and furnace

V. R. Prasad; N. Bhaskar Reddy; R. Muthucumaraswamy; B. Vasu

62

Long-term variability of high-mass X-ray binaries. I. Photometry  

NASA Astrophysics Data System (ADS)

We present photometric observations of the field around the optical counterparts of high-mass X-ray binaries. Our aim is to study the long-term photometric variability in correlation with their X-ray activity and derive a set of secondary standard stars that can be used for time series analysis. We find that the donors in Be/X-ray binaries exhibit larger amplitude changes in the magnitudes and colours than those hosting a supergiant companion. The amplitude of variability increases with wavelength in Be/X-ray binaries and remains fairly constant in supergiant systems. When time scales of years are considered, a good correlation between the X-ray and optical variability is observed. The X-rays cease when optical brightness decreases. These results reflect the fact that the circumstellar disk in Be/X-ray binaries is the main source of both optical and X-ray variability. We also derive the colour excess, E(B - V), selecting data at times when the contribution of the circumstellar disk was supposed to be at minimum, and we revisit the distance estimates. Finding charts with the identification of the secondary standard stars are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/A33

Reig, P.; Fabregat, J.

2015-02-01

63

Thermal radiation effects on magnetohydrodynamic free convection heat and mass transfer from a sphere in a variable porosity regime  

Microsoft Academic Search

Optically-dense, electrically-conducting fluid. Variable porosity. Permeable isothermal sphere embedded in a variable-porosity medium. Thermal radiation. Magnetohydrodynamic free convection heat and mass transfer.

V. Ramachandra Prasad; B. Vasu; O. Anwar Bég; Rana D. Parshad

2012-01-01

64

A Semi-empirical Mass-loss Rate in Short-period Cataclysmic Variables  

NASA Astrophysics Data System (ADS)

The mass-loss rate of donor stars in cataclysmic variables (CVs) is of paramount importance in the evolution of short-period CVs. Observed donors are oversized in comparison with those of isolated single stars of the same mass, which is thought to be a consequence of the mass loss. Using the empirical mass-radius relation of CVs and the homologous approximation for changes in effective temperature T 2, orbital period P, and luminosity of the donor with the stellar radius, we find the semi-empirical mass-loss rate {\\dot{M}_2} of CVs as a function of P. The derived {\\dot{M}_2} is at ~10-9.5-10-10 M sun yr-1 and weakly depends on P when P>90 minutes, while it declines very rapidly toward the minimum period when P < 90 minutes, emulating the P-T 2 relation. Due to strong deviation from thermal equilibrium caused by the mass loss, the semi-empirical {\\dot{M}_2} is significantly different from and has a less-pronounced turnaround behavior with P than suggested by previous numerical models. The semi-empirical P-{\\dot{M}_2} relation is consistent with the angular momentum loss due to gravitational wave emission and strongly suggests that CV secondaries with 0.075 M sun < M 2 < 0.2 M sun are less than 2 Gyr old. When applied to selected eclipsing CVs, our semi-empirical mass-loss rates are in good agreement with the accretion rates derived from the effective temperatures T 1 of white dwarfs, suggesting that {\\dot{M}_2} can be used to reliably infer T 2 from T 1. Based on the semi-empirical {\\dot{M}_2}, SDSS 1501 and 1433 systems that were previously identified as post-bounce CVs have yet to reach the minimal period.

Sirotkin, Fedir V.; Kim, Woong-Tae

2010-10-01

65

Variable/Multispeed Rotorcraft Drive System Concepts  

NASA Technical Reports Server (NTRS)

Several recent studies for advanced rotorcraft have identified the need for variable, or multispeed-capable rotors. A speed change of up to 50 percent has been proposed for future rotorcraft to improve vehicle performance. Varying rotor speed during flight not only requires a rotor capable of performing effectively over the extended operation speed and load range, but also requires an advanced propulsion system to provide the required speed changes. A study has been completed, which investigated possible drive system arrangements to accommodate up to the 50 percent speed change. These concepts are presented. The most promising configurations are identified and will be developed for future validation testing.

Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

2009-01-01

66

Variable phaseplates for focus invariant optical systems  

NASA Astrophysics Data System (ADS)

Depth of focus can be enhanced with cubic phaseplates located at the exit pupil of an optical system without significant loss of resolution. The enhancement factor is proportional to the strength of the phaseplate. The digital image is inversely filtered. The stronger the phaseplate is the stronger the inverse filter function must be. This causes increasing noise for high spatial frequencies in the restored image. Therefore, an optimum strength of the cubic phaseplate has to be chosen for the respective situation. A variable phaseplate system has been realized and tested. The performance of the setup has been experimentally studied. Applications and practical aspects are discussed in particular regarding barcode readers.

Hellmuth, T.; Bich, A.; Börret, R.; Holschbach, A.; Kelm, A.

2005-09-01

67

Water mass transformations and throughflow variability in the Indonesian seas  

Microsoft Academic Search

The main objective of this study is to examine factors that control the Indonesian throughflow and its variability. The study consists of three parts, an inverse analysis of tracer data along the throughflow pathways, analysis of the flow structure in the Makassar Strait, and dynamical study of the western Pacific. The inverse model analysis reveals aspects of the mixing process

Jorina Masarang Waworuntu

1999-01-01

68

THE ENIGMATIC YOUNG, LOW-MASS VARIABLE TWA 30  

E-print Network

TWA 30 is a remarkable young (7 ± 3 Myr), low-mass (0.12 ± 0.04 M [subscript ?]), late-type star (M5 ± 1) residing 42 ± 2 pc away from the Sun in the TW Hydrae Association (TWA). It shows strong outflow spectral signatures ...

Looper, Dagny L.

69

Probing the spatial and temporal variability of Enceladus mass-loading from ion cyclotron waves  

NASA Astrophysics Data System (ADS)

Enceladus plays a critical role in the Saturnian system by loading a significant amount of neutrals, ions and dust into the inner magnetosphere. Enceladus is also considered as the ultimate source for the dusty E-ring and the extended neutral cloud from 3.5 to 6.5 Saturn radii. When the freshly-added neutrals are ionized and accelerated by the electric and magnetic fields, left-handed electromagnetic waves, called ion cyclotron waves (ICW), grow from the free energy of the highly anisotropic distribution of these ions. The ICWs have been widely used to probe the rate of mass loading in different plasma environments in the solar system, because the wave power is proportional to the density and energy of the pickup ions. At Enceladus, ICWs are detected by Cassini not only near the moon but throughout the extended neutral cloud in all local times. However, the wave power is largely enhanced near the moon's longitude rather than far away from it. This indicates that on top of the relatively azimuthally-symmetric mass-loading source of the neutral cloud, there is a much denser cloud of neutrals centered on the moon and rotating with it. The latter source is the instantaneous mass-loading from plume of Enceladus, and it leads to asymmetry and dynamics in the magnetosphere. We investigate all available Cassini Enceladus flyby data to obtain a 3D spatial profile of the ICW power near the moon. By comparing with waves at longitudes far away from the moon, we investigate how significant is the plume mass-loading with respect to the neutral cloud mass-loading. We also compare the waves along several groups of identical trajectories to examine the temporal variability of the plume.

Wei, H.; Russell, C. T.; Powell, R. L.; Cowee, M.; Leisner, J. S.; Jia, Y.; Dougherty, M. K.

2013-12-01

70

A Method to Estimate the Masses of Asymptotic Giant Branch Variable Stars  

NASA Astrophysics Data System (ADS)

AGB variable stars are at the transient phase between low and high mass-loss rates; estimating the masses of these stars is necessary to study the evolutionary processes and mass-loss processes during the AGB stage. We applied the pulsation constant theoretically derived by Xiong and Deng (2007 MNRAS, 378, 1270) to 15 galactic AGB stars in order to estimate their masses. We found that using the pulsation constant is effective to estimate the mass of a star pulsating with two different pulsation modes, such as S Crt and RX Boo, which provides mass estimates comparable to theoretical results of AGB star evolution. We also extended the use of the pulsation constant to single-mode variables, and analyzed the properties of AGB stars related to their masses.

Takeuti, Mine; Nakagawa, Akiharu; Kurayama, Tomoharu; Honma, Mareki

2013-06-01

71

Variable Stars in the VVV Globular Clusters. I. 2MASS-GC 02 and Terzan 10  

NASA Astrophysics Data System (ADS)

The VISTA Variables in the Vía Láctea (VVV) ESO Public Survey is opening a new window to study inner Galactic globular clusters (GCs) using their variable stars. These GCs have been neglected in the past due to the difficulties caused by the presence of elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RR Lyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the questions raised by the intriguing Oosterhoff dichotomy in the Galactic GC system. In a series of papers we plan to explore variable stars in the GCs falling inside the field of the VVV survey. In this first paper, we search for and study the variables present in two highly reddened, moderately metal-poor, faint, inner Galactic GCs: 2MASS-GC 02 and Terzan 10. We report the discovery of sizable populations of RR Lyrae stars in both GCs. We use near-infrared period–luminosity relations to determine the color excess of each RR Lyrae star, from which we obtain both accurate distances to the GCs and the ratios of the selective-to-total extinction in their directions. We find the extinction toward both clusters to be elevated, non-standard, and highly differential. We also find both clusters to be closer to the Galactic center than previously thought, with Terzan 10 being on the far side of the Galactic bulge. Finally, we discuss their Oosterhoff properties, and conclude that both clusters stand out from the dichotomy followed by most Galactic GCs.

Alonso-García, Javier; Dékány, István; Catelan, Márcio; Contreras Ramos, Rodrigo; Gran, Felipe; Amigo, Pía; Leyton, Paul; Minniti, Dante

2015-03-01

72

Dual output variable pitch turbofan actuation system  

NASA Technical Reports Server (NTRS)

An improved actuating mechanism was provided for a gas turbine engine incorporating fan blades of the variable pitch variety, the actuator adapted to rotate the individual fan blades within apertures in an associated fan disc. The actuator included means such as a pair of synchronizing ring gears, one on each side of the blade shanks, and adapted to engage pinions disposed thereon. Means were provided to impart rotation to the ring gears in opposite directions to effect rotation of the blade shanks in response to a predetermined input signal. In the event of system failure, a run-away actuator was prevented by an improved braking device which arrests the mechanism.

Griswold, R. H., Jr.; Broman, C. L. (inventors)

1976-01-01

73

NEREUS Nemertes : embedded mass spectrometer control system  

E-print Network

In this thesis, I present Nemertes System, a software suite to control an embedded autonomous mass spectrometer. I first evaluate previous control systems for the hard- ware and evaluate a set of software design goals. The ...

Champy, Adam Samuel

2005-01-01

74

Moving mass trim control system design  

SciTech Connect

This paper describes the design of a moving mass trim control system for maneuvering axisymmetric reentry vehicles. The moving mass trim controller is composed of three equal masses that are independently positioned in order to deliver a desired center of mass position. For a slowly spinning reentry vehicle, the mass offset creates a trim angle-of-attack to generate modest flight path corrections. The control system must maintain the desired position of each mass in the face of large disturbances. A novel algorithm for determining the desired mass positions is developed in conjunction with a preliminary controller design. The controller design is based on classical frequency domain techniques where a bound on the disturbance magnitude is used to formulate the disturbance rejection problem. Simulation results for the controller are presented for a typical reentry vehicle.

Byrne, R.H.; Robinett, R.D.; Sturgis, B.R.

1996-03-01

75

Variable Speed Drive Volumetric Tracking (VSDVT) for Airflow Control in Variable Air Volume (VAV) Systems  

E-print Network

An airflow control method has been developed for variable air volume (VAV) systems. This airflow control method is named VSD volumetric tracking (VSDVT) since both the supply and return airflows are determined using signals of the variable speed...

Liu, M.

2002-01-01

76

The water mass variability on the Romanian Black Sea shelf  

NASA Astrophysics Data System (ADS)

The long-term trends in the water mass thermohaline structure and the effect of Danube River freshwater discharge into the western Black Sea during the last four decades (1971 - 2010) are analyzed using the data collected on the Romanian shelf (NIMRD data base). The variations of the temperature and salinity over the studied period are relatively small. The temperature data reveal a slightly warming trend for the upper mixed layer (UML) while for the shelf cold water (SCW) - identified by the 8?C upper isotherm depth - thermohaline structure remains practically constant. At the same time the salinity exhibits a decreasing trend in the entire water column.

Buga, Luminita; Mihailov, Maria-Emanuela; Malciu, Viorel; Stefan, Sabina

2013-04-01

77

Variable temperature seat climate control system  

DOEpatents

A temperature climate control system comprises a variable temperature seat, at least one heat pump, at least one heat pump temperature sensor, and a controller. Each heat pump comprises a number of Peltier thermoelectric modules for temperature conditioning the air in a main heat exchanger and a main exchanger fan for passing the conditioned air from the main exchanger to the variable temperature seat. The Peltier modules and each main fan may be manually adjusted via a control switch or a control signal. Additionally, the temperature climate control system may comprise a number of additional temperature sensors to monitor the temperature of the ambient air surrounding the occupant as well as the temperature of the conditioned air directed to the occupant. The controller is configured to automatically regulate the operation of the Peltier modules and/or each main fan according to a temperature climate control logic designed both to maximize occupant comfort during normal operation, and minimize possible equipment damage, occupant discomfort, or occupant injury in the event of a heat pump malfunction.

Karunasiri, Tissa R. (Van Nuys, CA); Gallup, David F. (Pasadena, CA); Noles, David R. (Glendale, CA); Gregory, Christian T. (Alhambra, CA)

1997-05-06

78

Variable acuity remote viewing system flight demonstration  

NASA Technical Reports Server (NTRS)

The Variable Acuity Remote Viewing System (VARVS), originally developed under contract to the Navy (ONR) as a laboratory brassboard, was modified for flight demonstration. The VARVS system was originally conceived as a technique which could circumvent the acuity/field of view/bandwidth tradeoffs that exists in remote viewing to provide a nearly eye limited display in both field of view (160 deg) and resolution (2 min arc) while utilizing conventional TV sensing, transmission, and display equipment. The modifications for flight demonstration consisted of modifying the sensor so it could be installed and flow in a Piper PA20 aircraft, equipped for remote control and modifying the display equipment so it could be integrated with the NASA Research RPB (RPRV) remote control cockpit.

Fisher, R. W.

1983-01-01

79

Assessment of the structure and variability of Weddell Sea water masses in distinct ocean reanalysis products  

NASA Astrophysics Data System (ADS)

We assessed and evaluated the performance of five ocean reanalysis products in reproducing essential hydrographic properties and their associated temporal variability for the Weddell Sea, Antarctica. The products used in this assessment were ECMWF ORAS4 (European Centre for Medium-Range Weather Forecasts Ocean Reanalysis System 4), CFSR (Climate Forecast System Reanalysis), MyOcean UR025.4 (University of Reading), ECCO2 (Estimating the Circulation and Climate of the Ocean, Phase II) and SODA (Simple Ocean Data Assimilation). The present study focuses on the Weddell Sea deep layer, which is composed of the following three main water masses: Warm Deep Water (WDW), Weddell Sea Deep Water (WSDW) and Weddell Sea Bottom Water (WSBW). The MyOcean UR025.4 product provided the most accurate representation of the structure and thermohaline properties of the Weddell Sea water masses when compared with observations. All the ocean reanalysis products analyzed exhibited limited capabilities in representing the surface water masses in the Weddell Sea. The CFSR and ECCO2 products were not able to represent deep water masses with a neutral density ? 28.40 kg m-3, which was considered the WSBW's upper limit throughout the simulation period. The expected WDW warming was only reproduced by the SODA product, whereas the ECCO2 product was able to represent the trends in the WSDW's hydrographic properties. All the assessed ocean reanalyses were able to represent the decrease in the WSBW's density, except the SODA product in the inner Weddell Sea. Improvements in parameterization may have as much impact on the reanalyses assessed as improvements in horizontal resolution primarily because the Southern Ocean lacks in situ data, and the data that are currently available are summer-biased. The choice of the reanalysis product should be made carefully, taking into account the performance, the parameters of interest, and the type of physical processes to be evaluated.

Dotto, T. S.; Kerr, R.; Mata, M. M.; Azaneu, M.; Wainer, I.; Fahrbach, E.; Rohardt, G.

2014-06-01

80

X-ray spectral and variability properties of low-mass active galactic nuclei  

NASA Astrophysics Data System (ADS)

We study the X-ray properties of a sample of 14 optically selected low-mass active galactic nuclei (AGN) whose masses lie within the range 105-2 × 106 M? with XMM-Newton. Only six of these low-mass AGN have previously been studied with sufficient quality X-ray data, thus, we have more than double the number of low-mass AGN observed by XMM-Newton with the addition of our sample. We analyse their X-ray spectral properties and variability and compare the results to their more massive counterparts. The presence of a soft X-ray excess is detectable in all five objects which were not background dominated at 2-3 keV. Combined with previous studies, this gives a total of eight low-mass AGN with a soft excess. The low-mass AGN exhibit rapid, short-term variability (hundreds to thousands of seconds) and long-term variability (months to years). There is a well-known anticorrelation between black hole mass and variability amplitude (normalized excess variance). Comparing our sample of low-mass AGN with this relation we find that all of our sample lie below an extrapolation of the linear relation. Such a flattening of the relation at low masses (below ˜106 M?) is expected if the variability in all AGN follows the same shape power spectrum with a break frequency that is dependent on mass. Finally, we also found two objects that show significant absorption in their X-ray spectrum, indicative of type 2 objects, although they are classified as type 1 AGN based on optical spectra.

Ludlam, R. M.; Cackett, E. M.; Gültekin, K.; Fabian, A. C.; Gallo, L.; Miniutti, G.

2015-03-01

81

Equations of motion for the variable mass flow-variable exhaust velocity rocket  

NASA Technical Reports Server (NTRS)

An equation of motion for a one dimensional rocket is derived as a function of the mass flow rate into the acceleration chamber and the velocity distribution along the chamber, thereby including the transient flow changes in the chamber. The derivation of the mass density requires the introduction of the special time coordinate. The equation of motion is derived from both classical force and momentum approaches and is shown to be consistent with the standard equation expressed in terms of flow parameters at the exit to the acceleration chamber.

Tempelman, W. H.

1972-01-01

82

Air Pressure Controlled Mass Measurement System  

NASA Astrophysics Data System (ADS)

Mass measurement is influenced by air pressure, temperature, humidity and other facts. In order to reduce the influence, mass laboratory of National Institute of Metrology, China has developed an air pressure controlled mass measurement system. In this system, an automatic mass comparator is installed in an airtight chamber. The Chamber is equipped with a pressure controller and associate valves, thus the air pressure can be changed and stabilized to the pre-set value, the preferred pressure range is from 200 hPa to 1100 hPa. In order to keep the environment inside the chamber stable, the display and control part of the mass comparator are moved outside the chamber, and connected to the mass comparator by feed-throughs. Also a lifting device is designed for this system which can easily lift up the upper part of the chamber, thus weights can be easily put inside the mass comparator. The whole system is put on a marble platform, and the temperature and humidity of the laboratory is very stable. The temperature, humidity, and carbon dioxide content inside the chamber are measured in real time and can be used to get air density. Mass measurement cycle from 1100 hPa to 200 hPa and back to 1100 hPa shows the effective of the system.

Zhong, Ruilin; Wang, Jian; Cai, Changqing; Yao, Hong; Ding, Jin'an; Zhang, Yue; Wang, Xiaolei

83

Gas sampling system for a mass spectrometer  

DOEpatents

The present invention relates generally to a gas sampling system, and specifically to a gas sampling system for transporting a hazardous process gas to a remotely located mass spectrometer. The gas sampling system includes a capillary tube having a predetermined capillary length and capillary diameter in communication with the supply of process gas and the mass spectrometer, a flexible tube surrounding and coaxial with the capillary tube intermediate the supply of process gas and the mass spectrometer, a heat transfer tube surrounding and coaxial with the capillary tube, and a heating device in communication the heat transfer tube for substantially preventing condensation of the process gas within the capillary tube.

2003-12-30

84

INFRARED VARIABILITY OF THE GLIESE 569B SYSTEM  

SciTech Connect

Gliese 569B is a multiple brown dwarf system whose exact nature has been the subject of several investigations over the past few years. Interpretation has partially relied on infrared photometry and spectroscopy of the resolved components of the system. We present seeing-limited K{sub s} photometry over four nights, searching for variability in this young low-mass substellar system. Our photometry is consistent with other reported photometry, and we report the tentative detection of several periodic signals consistent with rotational modulation due to spots on their surfaces. The five significant periods range from 2.90 hr to 12.8 hr, with peak-to-peak variabilities from 28 mmag to 62 mmag in the K{sub s} band. If both components are rotating with the shortest periods, then their rotation axes are not parallel with each other, and the rotation axis of the Bb component is not perpendicular to the Ba-Bb orbital plane. If Bb has one of the longer rotational periods, then the Bb rotation axis is consistent with being parallel to the orbital axis of the Ba-Bb system.

Kenworthy, Matthew A. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Scuderi, Louis J., E-mail: kenworthy@strw.leidenuniv.nl [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822-1839 (United States)

2012-06-20

85

Mass Storage Performance Information System  

NASA Technical Reports Server (NTRS)

The purpose of this task is to develop a data warehouse to enable system administrators and their managers to gather information by querying the data logs of the MDSDS. Currently detailed logs capture the activity of the MDSDS internal to the different systems. The elements to be included in the data warehouse are requirements analysis, data cleansing, database design, database population, hardware/software acquisition, data transformation, query and report generation, and data mining.

Scheuermann, Peter

2000-01-01

86

An Analysis of Space Power System Masses  

Microsoft Academic Search

This paper analyzes various space electrical power system masses with particular emphasis on the power management and distribution (PMAD) portion. The electrical power system (EPS) is divided into functional blocks: source, interconnection, storage, transmission, distribution, system control and load. The PMAD subsystem is defined as all the blocks between the source, storage and load, plus the power conditioning equipment required

Barbara H. Kenny; Ronald C. Cull; M. David Kankam

1990-01-01

87

Asymmetric EPR entanglement in continuous variable systems  

E-print Network

Continuous variable entanglement can be produced in nonlinear systems or via interference of squeezed states. In many of optical systems, such as parametric down conversion or interference of optical squeezed states, production of two perfectly symmetric subsystems is usually used for demonstrating the existence of entanglement. This symmetry simplifies the description of the concept of entanglement. However, asymmetry in entanglement may arise naturally in a real experiment, or be intentionally introduced in a given quantum information protocol. These asymmetries can emerge from having the output beams experience different losses and environmental contamination, or from the availability of non-identical input quantum states in quantum communication protocols. In this paper, we present a visualisation of entanglement using quadrature amplitude plots of the twin beams. We quantitatively discuss the strength of asymmetric entanglement using EPR and inseparability criteria and theoretically show that the optimal beamsplitter ratio for entanglement is dependent on the asymmetries and may not be 50/50. To support this theory, we present experimental results showing one particular asymmetric entanglement where a 0.78/0.22 beamsplitter is optimal for observing entanglement.

Katherine Wagner; Jiri Janousek; Seiji Armstrong; Jean-Francois Morizur; Ping Koy Lam; Hans-Albert Bachor

2012-03-09

88

Asymmetric EPR entanglement in continuous variable systems  

NASA Astrophysics Data System (ADS)

Continuous variable entanglement can be produced in nonlinear systems or via the interference of squeezed states. In many optical systems such as parametric down conversion, the production of two perfectly symmetric subsystems is usually assumed when demonstrating the existence of entanglement. This symmetry simplifies the description of entanglement. However, asymmetry in entanglement may arise naturally in a real experiment, or be intentionally introduced in a given quantum information protocol. These asymmetries can emerge from having the output beams experience different losses and environmental contamination, or from the availability of non-identical input quantum states in quantum communication protocols. In this paper, we present a visualization of entanglement using quadrature amplitude plots of the twin beams. We quantitatively discuss the strength of asymmetric entanglement using EPR and inseparability criteria and theoretically show that the optimal beamsplitter ratio for entanglement is dependent on the asymmetries and may not be 50 : 50. To support this theory, we present experimental results showing one particular asymmetric entanglement where a 78 : 22 beamsplitter is optimal for observing entanglement.

Wagner, Katherine; Janousek, Jiri; Armstrong, Seiji; Morizur, Jean-François; Lam, Ping Koy; Bachor, Hans-Albert

2014-11-01

89

THE MASS-RICHNESS RELATION OF MaxBCG CLUSTERS FROM QUASAR LENSING MAGNIFICATION USING VARIABILITY  

SciTech Connect

Accurate measurement of galaxy cluster masses is an essential component not only in studies of cluster physics but also for probes of cosmology. However, different mass measurement techniques frequently yield discrepant results. The Sloan Digital Sky Survey MaxBCG catalog's mass-richness relation has previously been constrained using weak lensing shear, Sunyaev-Zeldovich (SZ), and X-ray measurements. The mass normalization of the clusters as measured by weak lensing shear is {approx}>25% higher than that measured using SZ and X-ray methods, a difference much larger than the stated measurement errors in the analyses. We constrain the mass-richness relation of the MaxBCG galaxy cluster catalog by measuring the gravitational lensing magnification of type I quasars in the background of the clusters. The magnification is determined using the quasars' variability and the correlation between quasars' variability amplitude and intrinsic luminosity. The mass-richness relation determined through magnification is in agreement with that measured using shear, confirming that the lensing strength of the clusters implies a high mass normalization and that the discrepancy with other methods is not due to a shear-related systematic measurement error. We study the dependence of the measured mass normalization on the cluster halo orientation. As expected, line-of-sight clusters yield a higher normalization; however, this minority of haloes does not significantly bias the average mass-richness relation of the catalog.

Bauer, Anne H. [Institut de Ciencies de l'Espai, CSIC/IEEC, F. de Ciencies, Torre C5 par-2, Barcelona 08193 (Spain); Baltay, Charles; Ellman, Nancy; Jerke, Jonathan; Rabinowitz, David; Scalzo, Richard, E-mail: bauer@ieec.uab.es [Yale University, Department of Physics, P.O. Box 208120, New Haven, CT 06520-8120 (United States)

2012-04-10

90

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling convertor. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G.

2009-01-01

91

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140° C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G.

2009-03-01

92

Online mass storage system detailed requirements document  

NASA Technical Reports Server (NTRS)

The requirements for an online high density magnetic tape data storage system that can be implemented in a multipurpose, multihost environment is set forth. The objective of the mass storage system is to provide a facility for the compact storage of large quantities of data and to make this data accessible to computer systems with minimum operator handling. The results of a market survey and analysis of candidate vendor who presently market high density tape data storage systems are included.

1976-01-01

93

Superintegrable systems with position dependent mass  

E-print Network

First order integrals of motion for Schr\\"odinger equations with position dependent masses are classified. Seventeen classes of such equations with non-equivalent symmetries are specified. They include integrable, superintegrable and maximally superintegrable systems. Among them is a system invariant with respect to the Lie algebra of Lorentz group and a system whose integrals of motion form algebra so(4). Three of the obtained systems are solved exactly.

A. G. Nikitin; T. M. Zasadko

2014-06-08

94

Superintegrable systems with position dependent mass  

E-print Network

First order integrals of motion for Schr\\"odinger equations with position dependent masses are classified. Seventeen classes of such equations with non-equivalent symmetries are specified. They include integrable, superintegrable and maximally superintegrable systems. Among them is a system invariant with respect to the Lie algebra of Lorentz group and a system whose integrals of motion form algebra so(4). Three of the obtained systems are solved exactly.

A. G. Nikitin; T. M. Zasadko

2015-03-27

95

An analysis of space power system masses  

NASA Technical Reports Server (NTRS)

Various space electrical power system masses are analyzed with particular emphasis on the power management and distribution (PMAD) portion. The electrical power system (EPS) is divided into functional blocks: source, interconnection, storage, transmission, distribution, system control and load. The PMAD subsystem is defined as all the blocks between the source, storage and load, plus the power conditioning equipment required for the source, storage and load. The EPS mass of a wide range of spacecraft is then classified as source, storage or PMAD and tabulated in a database. The intent of the database is to serve as a reference source for PMAD masses of existing and in-design spacecraft. The PMAD masses in the database range from 40 kg/kW to 183 kg/kW across the spacecraft systems studied. Factors influencing the power system mass are identified. These include the total spacecraft power requirements, total amount of load capacity and physical size of the spacecraft. It is found that a new utility class of power systems, represented by Space Station Freedom, is evolving.

Kenny, Barbara H.; Cull, Ronald C.; Kankam, M. David

1990-01-01

96

Assessment of the structure and variability of Weddell Sea water masses in distinct ocean reanalysis products  

NASA Astrophysics Data System (ADS)

We assessed and evaluated the performance of five ocean reanalysis in reproducing essential hydrographic properties and their associated temporal variability for the Weddell Sea, Antarctica. The products used in this assessment were ECMWF ORAS4, CFSR, MyOcean UR025.4, ECCO2 and SODA. The present study focuses on the Weddell Sea deep layer, which is composed of the following three main water masses: Warm Deep Water (WDW), Weddell Sea Deep Water (WSDW) and Weddell Sea Bottom Water (WSBW). Moreover, all the ocean reanalysis products analyzed showed limited capabilities in representing the surface water masses in the Weddell Sea. The MyOcean UR025.4 product provided the most accurate representation of the structure of the Weddell Sea water masses when compared to observations. The CFSR and ECCO2 products were not able to represent the WSBW throughout the simulation period. The expected WDW warming was only reproduced by the SODA product, while the ECCO2 product was able to represent the WSDW's hydrographic properties trends. All of these ocean reanalysis systems were able to represent the decrease in the WSBW's density. Our results also showed that a simple increase in horizontal resolution does not necessarily imply better representation of the deep layers. Rather, it is needed to observe the physics involved in each model and their parameterizations because the Southern Ocean suffers from the lack of in situ data, and it is biased by summer observations. The choice of the reanalysis product should be made carefully, taking into account the performance, the parameters of interest, and the type of physical processes to be evaluated.

Dotto, T. S.; Kerr, R.; Mata, M. M.; Azaneu, M.; Wainer, I.

2014-02-01

97

System-Level Integration of Mass Memory  

NASA Technical Reports Server (NTRS)

A report discusses integrating multiple memory modules on the high-speed serial interconnect (IEEE 1393) that is used by a spacecraft?s inter-module communications in order to ease data congestion and provide for a scalable, strong, flexible system that can meet new system-level mass memory requirements.

Cox, Brian; Mellstrom, Jeffrey; Wysocky, Terry

2008-01-01

98

Dark-Spot Activity on the Secondary as the Origin of Variable Mass Accretion in Cataclysmic Variables  

NASA Astrophysics Data System (ADS)

In magnetic CVs (polars), the magnetic fields of the white dwarfs are strong enough to prevent materials from the main-sequence companions for forming an accretion disc. Therefore, polars especially eclipsing polars provide a good chance to study mass accretion directly. In the past 4 years, we have monitored several eclipsing polars (e.g., DP Leo and HU Aqr) by using the 2.4-m and 1.0-m telescopes in China and the 2.15-m telescope in Argentina. Nearly 100 eclipse profiles were obtained. In this talk, apart from the detection of a few giant planets orbiting polars, I will summarize some other progresses of our research group at Yunnan Observatories. Our results are as following: (1) the correlation between the out-of-eclipse brightness variation and the change of the eclipse profile suggests that both the accretion hot spot and the accretion stream brighten and become faint instantaneously. This is the direct evidence of variable mass transfer in a CV that is also supported by the relation between the out-of-eclipse brightness and the depth of eclipse. (2) We find the brightness state change is correlated with the dark-spot activity near the L1 point. The low state usually corresponds to the presence of a large spot at L1 point, while the dark spot disappear at a high state indicating that it is the dark-spot activity caused the mass transfer in CVs. (3) Magnetic activity cycles of the cool secondary did not correlate with the brightness state change revealing the variable mass accretion was not caused by magnetic activity cycles.

Qian, S.-B.; Zhu, L.-Y.; Fernández-Lajús, E.; He, J.-J.; Liao, W.-P.; Zhao, E.-G.; Liu, L.; Yang, Y.-G.

2014-08-01

99

SLIDING MODE VARIABLE STRUCTURE CONTROL FOR UNCERTAIN STOCHASTIC SYSTEMS  

Microsoft Academic Search

Abstract. In this paper, the sliding mode variable structure control for a class of uncer- tain stochastic systems is investigated . Firstly, the sliding surface is established and the variable structure control law of the system is designed. Then it is proved that the sliding mode,is subordinated reachable and a sufficient condition for mean-square asymptotical stability of the sliding mode

Xiaozhu Zhong; Hailong Xing; Kuniaki Fujimoto

100

On observers in multi-variable control systems  

Microsoft Academic Search

Many feedback control system designs require the availability of the state of the controlled plant. Since the plant state variables are not generally available for direct measurement in practice a means for estimating these variables is required. Attention is restricted to plants which are linear, time-invariant, finite-dimensional, dynamic systems in this paper. In this case, necessary and sufficient conditions are

J. J. BONGIORNO JR; D. C. YOULA

1968-01-01

101

Variable neural networks for adaptive control of nonlinear systems  

Microsoft Academic Search

This paper is concerned with the adaptive control of continuous-time nonlinear dynamical systems using neural networks. A novel neural network architecture, referred to as a variable neural network, is proposed and shown to be useful in approximating the unknown nonlinearities of dynamical systems. In the variable neural networks, the number of basis functions can be either increased or decreased with

Guoping P. Liu; Visakan Kadirkamanathan; Stephen A. Billings

1999-01-01

102

Climate variability and deep water mass characteristics in the Aegean Sea  

NASA Astrophysics Data System (ADS)

The main objective of this study is to investigate the variability of the thermohaline characteristics of the deep-water masses in the Aegean Sea and the possible impact of the regional atmospheric forcing variability by analyzing the available oceanographic and atmospheric datasets for the period of 1960-2012. During this period the variability of the deep water characteristics of the Aegean sub-basins is found to be very large as well as the diversity of the deep water characteristics among the sub-basins. The Central Aegean seems to play the key role in the Aegean deep water formation processes. Due to its small size, the Aegean Sea surface responds rapidly to the meteorological changes and/or the variability of the lateral fluxes and this variability propagates in the thermohaline characteristics of the deep water masses of the basin through deep water formation processes. There are many episodes characterized by a tight coupling of the atmosphere and the ocean during the examined period, with the Eastern Mediterranean Transient (EMT) being the most prominent case. We suggest that deep water formation is triggered mostly by the combination of preconditioning during early winter and/or previous winters together with the number of subsequent extreme events during present winter and not only by the total amount of the extreme heat loss winter days.

Georgiou, S.; Mantziafou, A.; Sofianos, S.; Gertman, I.; Özsoy, E.; Somot, S.; Vervatis, V.

2015-01-01

103

Toward Scalable Benchmarks for Mass Storage Systems  

NASA Technical Reports Server (NTRS)

This paper presents guidelines for the design of a mass storage system benchmark suite, along with preliminary suggestions for programs to be included. The benchmarks will measure both peak and sustained performance of the system as well as predicting both short- and long-term behavior. These benchmarks should be both portable and scalable so they may be used on storage systems from tens of gigabytes to petabytes or more. By developing a standard set of benchmarks that reflect real user workload, we hope to encourage system designers and users to publish performance figures that can be compared with those of other systems. This will allow users to choose the system that best meets their needs and give designers a tool with which they can measure the performance effects of improvements to their systems.

Miller, Ethan L.

1996-01-01

104

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

SciTech Connect

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 deg. C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G. [Advanced Cooling Technologies, Inc. 1046 New Holland Ave. Lancaster, PA 17601 (United States)

2009-03-16

105

Studies of Long Period Variability in Neutron Star HMXB Systems  

NASA Technical Reports Server (NTRS)

The purpose of this effort was to investigate the long term, quasi-periodic variability of the X-ray emission from the accreting X-ray pulsars LMC X-4 and SMC X-1. These high mass X-ray binary (HMXB) sources are known to vary in a nearly periodic fashion with cycle lengths of about 30 and 60 days respectively. The prevailing model for such behavior is that it is due to the precession of a tilted accretion disk around the neutron star which is the source of the X-ray emission. As the disk precesses, it periodically obscures the emitting region, resulting in reduced flux as observed at the Earth. The obscuration is not strictly periodic, as the disk precession period changes as the total mass and size of the disk change through variable accretion processes. This model is well established for the long-period variability in the X-ray pulsar Her X-1. With this work, my collaborators and I sought to test whether this model works for LMC X-4 and SMC X-1. Observations with the pointed instruments on the Rossi X-ray Timing Explorer (RXTE) were carried out in order to observe changes in the X-ray spectrum and total flux which were correlated with the long period cycles in these objects. One of the main predictions of the precessing disk model is that the periods of low emission are caused not by changes in the central source, but by increased absorption of that flux as seen at the Earth. Such behavior would be observed in the X-ray spectrum as a relative lack of low energy X-rays (which are more easily absorbed) as compared to high energy X-rays. This is what was observed for SMC X-1, landing strong support to the precessing disk model for this system. For LMC X-1, however, the absorption was consistent with zero at the time of minimum flux. The entire spectrum appeared to be equally reduced. This is not supporting evidence for the model. However, it also does not rule out a precessing disk. If at the time of minimum flux, the intervening disk is so thick that no flux, even high energy X-rays, can penetrate, and if there is material above the disk which can scatter X-rays, then a small scattered spectrum will be seen which is indistinguishable from the unobscured source flux. This is quite possibly the case in LMC X-1.

Heindl, William A.

1998-01-01

106

The Secondary Star in Cataclysmic Variables and Low Mass X-ray Binaries  

E-print Network

We critically re-examine the available data on the spectral types, masses and radii of the secondary stars in cataclysmic variables (CVs) and low-mass X-ray binaries (LMXBs), using the new catalogue of Ritter & Kolb (1998) as a starting point. We find there are 55 reliable spectral type determinations and only 14 reliable mass determinations of CV secondary stars (10 and 5, respectively, in the case of LMXBs). We derive new spectral type-period, mass-radius, mass-period and radius-period relations, and compare them with theoretical predictions. We find that CV secondary stars with orbital periods shorter than 7-8 hours are, as a group, indistinguishable from main sequence stars in detached binaries. We find it is not valid, however, to estimate the mass from the spectral type of the secondary star in CVs or LMXBs. We find that LMXB secondary stars show some evidence for evolution, with secondary stars which are slightly too large for their mass. We show how the masses and radii of the secondary stars in CVs can be used to test the validity of the disrupted magnetic braking model of CV evolution, but we find that the currently available data are not sufficiently accurate or numerous to allow such an analysis. As well as considering secondary star masses, we also discuss the masses of the white dwarfs in CVs, and find mean values of M_1 = 0.69+/-0.13 M_sun below the period gap, and M_1 = 0.80+/-0.22 M_sun above the period gap.

D. A. Smith; V. S. Dhillon

1998-08-20

107

Relativistic Electromagnetic Mass Models With Cosmological Variable$?$ in Spherically Symmetric Anisotropic Source  

E-print Network

A class of exact solutions for the Einstein-Maxwell field equations are obtained by assuming the erstwhile cosmological constant $ \\Lambda $ to be a space-variable scalar, viz., $ \\Lambda =\\Lambda(r) $. The source considered here is static, spherically symmetric and anisotropic charged fluid. The solutions obtained are matched continuously to the exterior Reissner-Nordstr\\"{o}m solution and each of the four solutions represents an electromagnetic mass model.

R. N. Tiwari; Saibal Ray; Sumana Bhadra

2011-03-03

108

Variable-speed capacity control in refrigeration systems  

Microsoft Academic Search

This paper presents a review of the application of variable-speed capacity control to refrigeration systems. The aim is to put together diversified information in a single source and to appraise recent advances in variable-speed technology. The review reveals that although variable-speed drives based on inverters have been applied successfully to control the capacity of rotodynamic machines, such as pumps and

T. Q. Qureshi; S. A. Tassou

1996-01-01

109

Neutral particle mass spectrometry with nanomechanical systems  

NASA Astrophysics Data System (ADS)

Current approaches to mass spectrometry (MS) require ionization of the analytes of interest. For high-mass species, the resulting charge state distribution can be complex and difficult to interpret correctly. Here, using a setup comprising both conventional time-of-flight MS (TOF-MS) and nano-electromechanical systems-based MS (NEMS-MS) in situ, we show directly that NEMS-MS analysis is insensitive to charge state: the spectrum consists of a single peak whatever the species’ charge state, making it significantly clearer than existing MS analysis. In subsequent tests, all the charged particles are electrostatically removed from the beam, and unlike TOF-MS, NEMS-MS can still measure masses. This demonstrates the possibility to measure mass spectra for neutral particles. Thus, it is possible to envisage MS-based studies of analytes that are incompatible with current ionization techniques and the way is now open for the development of cutting-edge system architectures with unique analytical capability.

Sage, Eric; Brenac, Ariel; Alava, Thomas; Morel, Robert; Dupré, Cécilia; Hanay, Mehmet Selim; Roukes, Michael L.; Duraffourg, Laurent; Masselon, Christophe; Hentz, Sébastien

2015-03-01

110

Neutral particle mass spectrometry with nanomechanical systems  

PubMed Central

Current approaches to mass spectrometry (MS) require ionization of the analytes of interest. For high-mass species, the resulting charge state distribution can be complex and difficult to interpret correctly. Here, using a setup comprising both conventional time-of-flight MS (TOF-MS) and nano-electromechanical systems-based MS (NEMS-MS) in situ, we show directly that NEMS-MS analysis is insensitive to charge state: the spectrum consists of a single peak whatever the species’ charge state, making it significantly clearer than existing MS analysis. In subsequent tests, all the charged particles are electrostatically removed from the beam, and unlike TOF-MS, NEMS-MS can still measure masses. This demonstrates the possibility to measure mass spectra for neutral particles. Thus, it is possible to envisage MS-based studies of analytes that are incompatible with current ionization techniques and the way is now open for the development of cutting-edge system architectures with unique analytical capability. PMID:25753929

Sage, Eric; Brenac, Ariel; Alava, Thomas; Morel, Robert; Dupré, Cécilia; Hanay, Mehmet Selim; Roukes, Michael L.; Duraffourg, Laurent; Masselon, Christophe; Hentz, Sébastien

2015-01-01

111

Neutral particle mass spectrometry with nanomechanical systems.  

PubMed

Current approaches to mass spectrometry (MS) require ionization of the analytes of interest. For high-mass species, the resulting charge state distribution can be complex and difficult to interpret correctly. Here, using a setup comprising both conventional time-of-flight MS (TOF-MS) and nano-electromechanical systems-based MS (NEMS-MS) in situ, we show directly that NEMS-MS analysis is insensitive to charge state: the spectrum consists of a single peak whatever the species' charge state, making it significantly clearer than existing MS analysis. In subsequent tests, all the charged particles are electrostatically removed from the beam, and unlike TOF-MS, NEMS-MS can still measure masses. This demonstrates the possibility to measure mass spectra for neutral particles. Thus, it is possible to envisage MS-based studies of analytes that are incompatible with current ionization techniques and the way is now open for the development of cutting-edge system architectures with unique analytical capability. PMID:25753929

Sage, Eric; Brenac, Ariel; Alava, Thomas; Morel, Robert; Dupré, Cécilia; Hanay, Mehmet Selim; Roukes, Michael L; Duraffourg, Laurent; Masselon, Christophe; Hentz, Sébastien

2015-01-01

112

Using System Mass (SM), Equivalent Mass (EM), Equivalent System Mass (ESM) or Life Cycle Mass (LCM) in Advanced Life Support (ALS) Reporting  

NASA Technical Reports Server (NTRS)

The Advanced Life Support (ALS) has used a single number, Equivalent System Mass (ESM), for both reporting progress and technology selection. ESM is the launch mass required to provide a space system. ESM indicates launch cost. ESM alone is inadequate for technology selection, which should include other metrics such as Technology Readiness Level (TRL) and Life Cycle Cost (LCC) and also consider perfom.arxe 2nd risk. ESM has proven difficult to implement as a reporting metric, partly because it includes non-mass technology selection factors. Since it will not be used exclusively for technology selection, a new reporting metric can be made easier to compute and explain. Systems design trades-off performance, cost, and risk, but a risk weighted cost/benefit metric would be too complex to report. Since life support has fixed requirements, different systems usually have roughly equal performance. Risk is important since failure can harm the crew, but it is difficult to treat simply. Cost is not easy to estimate, but preliminary space system cost estimates are usually based on mass, which is better estimated than cost. Amass-based cost estimate, similar to ESM, would be a good single reporting metric. The paper defines and compares four mass-based cost estimates, Equivalent Mass (EM), Equivalent System Mass (ESM), Life Cycle Mass (LCM), and System Mass (SM). EM is traditional in life support and includes mass, volume, power, cooling and logistics. ESM is the specifically defined ALS metric, which adds crew time and possibly other cost factors to EM. LCM is a new metric, a mass-based estimate of LCC measured in mass units. SM includes only the factors of EM that are originally measured in mass, the hardware and logistics mass. All four mass-based metrics usually give similar comparisons. SM is by far the simplest to compute and easiest to explain.

Jones, Harry

2003-01-01

113

Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP turns on with a delta T of 30 C, which is high enough to not risk standard ASRG operation but low enough to save most heater head life. This VCHP has a low mass, and low thermal losses for normal operation. In addition to the design, a proof-of-concept NaK VCHP was fabricated and tested. While NaK is normally not used in heat pipes, it has an advantage in that it is liquid at the reservoir operating temperature, while Na or K alone would freeze. The VCHP had two condensers, one simulating the heater head, and the other simulating the radiator. The experiments successfully demonstrated operation with the simulated heater head condenser off and on, while allowing the reservoir temperature to vary over 40 to 120 C, the maximum range expected. In agreement with previous NaK heat pipe tests, the evaporator delta T was roughly 70 C, due to distillation of the NaK in the evaporator.

Anderson, William G.; Tarau, Calin

2008-01-01

114

Error response test system and method using test mask variable  

NASA Technical Reports Server (NTRS)

An error response test system and method with increased functionality and improved performance is provided. The error response test system provides the ability to inject errors into the application under test to test the error response of the application under test in an automated and efficient manner. The error response system injects errors into the application through a test mask variable. The test mask variable is added to the application under test. During normal operation, the test mask variable is set to allow the application under test to operate normally. During testing, the error response test system can change the test mask variable to introduce an error into the application under test. The error response system can then monitor the application under test to determine whether the application has the correct response to the error.

Gender, Thomas K. (Inventor)

2006-01-01

115

Variable structure methods in hydraulic servo systems control  

Microsoft Academic Search

In the general framework of hydraulic servo systems, this paper addresses the problem of position control in the presence of important friction nonlinearities. The accent falls on the variable structure methodology, as we try to use its intrinsic robustness properties. Several friction observers, including the one based on a variable structure approach, were incorporated and tested in an acceleration feedback

Adrian Bonchis; Peter I. Corke; David C. Rye; Quang P. Ha

2001-01-01

116

Expert overseer for mass spectrometer system  

DOEpatents

An expert overseer for the operation and real-time management of a mass spectrometer and associated laboratory equipment. The overseer is a computer-based expert diagnostic system implemented on a computer separate from the dedicated computer used to control the mass spectrometer and produce the analysis results. An interface links the overseer to components of the mass spectrometer, components of the laboratory support system, and the dedicated control computer. Periodically, the overseer polls these devices and as well as itself. These data are fed into an expert portion of the system for real-time evaluation. A knowledge base used for the evaluation includes both heuristic rules and precise operation parameters. The overseer also compares current readings to a long-term database to detect any developing trends using a combination of statistical and heuristic rules to evaluate the results. The overseer has the capability to alert lab personnel whenever questionable readings or trends are observed and provide a background review of the problem and suggest root causes and potential solutions, or appropriate additional tests that could be performed. The overseer can change the sequence or frequency of the polling to respond to an observation in the current data.

Filby, Evan E. (Idaho Falls, ID); Rankin, Richard A. (Ammon, ID)

1991-01-01

117

MASS ACTION IN THE NERVOUS SYSTEM WALTER J. FREEMAN  

E-print Network

MASS ACTION IN THE NERVOUS SYSTEM in the nervous system. Bibliography: p. Includes indexes. Neurophysiologyâ??Mathematical models. Adaptation IN THE UNITED STATES OF AMERICA #12; MASS ACTION IN THE NERVOUS SYSTEM Contents PREFACE

Freeman, Walter J.

118

A NEW SAMPLE OF CANDIDATE INTERMEDIATE-MASS BLACK HOLES SELECTED BY X-RAY VARIABILITY  

SciTech Connect

We present the results of X-ray variability and spectral analysis of a sample of 15 new candidates for active galactic nuclei with relatively low-mass black holes (BHs). They are selected from the Second XMM-Newton Serendipitous Source Catalogue based on strong variability quantified by normalized excess variances. Their BH masses are estimated to be (1.1-6.6) Multiplication-Sign 10{sup 6} M{sub Sun} by using a correlation between excess variance and BH mass. Seven sources have estimated BH masses smaller than 2 Multiplication-Sign 10{sup 6} M{sub Sun }, which are in the range for intermediate-mass black holes. Eddington ratios of sources with known redshifts range from 0.07 to 0.46 and the mean Eddington ratio is 0.24. These results imply that some of our sources are growing supermassive black holes, which are expected to have relatively low masses with high Eddington ratios. X-ray photon indices of the 15 sources are in the range of Almost-Equal-To 0.57-2.57 and 5 among them have steep (>2) photon indices, which are the range for narrow-line Seyfert 1s. Soft X-ray excess is seen in 12 sources and is expressed by a blackbody model with kT Almost-Equal-To 83-294 eV. We derive a correlation between X-ray photon indices and Eddington ratios, and find that the X-ray photon indices of about a half of our sources are flatter than the positive correlation suggested previously.

Kamizasa, Naoya; Terashima, Yuichi; Awaki, Hisamitsu [Department of Physics, Ehime University, Matsuyama, Ehime 790-8577 (Japan)

2012-05-20

119

Development of Variable Camber Continuous Trailing Edge Flap System  

NASA Technical Reports Server (NTRS)

This presentation describes the current status of the joint NASA/Boeing collaboration on the development of a variable camber continuous trailing edge flap system for use in wing shaping control for cruise drag reduction.

Urnes, Jim, Sr.; Nguyen, Nhan T.; Dykman, John

2012-01-01

120

Solving Systems of Linear Equations in Two Variables  

NSDL National Science Digital Library

This tutorial on solving systems of linear equations in two variables walks students through each step of solving, and provides a handy video lesson at the end in which an instructor guides the viewer through the solution.

2012-08-13

121

Mass spectrometer vacuum housing and pumping system  

DOEpatents

A vacuum housing and pumping system is described for a portable gas chromatograph/mass spectrometer (GC/MS). The vacuum housing section of the system has minimum weight for portability while designed and constructed to utilize metal gasket sealed stainless steel to be compatible with high vacuum operation. The vacuum pumping section of the system consists of a sorption (getter) pump to remove atmospheric leakage and outgassing contaminants as well as the gas chromatograph carrier gas (hydrogen) and an ion pump to remove the argon from atmospheric leaks. The overall GC/MS system has broad application to contaminants, hazardous materials, illegal drugs, pollution monitoring, etc., as well as for use by chemical weapon treaty verification teams, due to the light weight and portability thereof. 7 figs.

Coutts, G.W.; Bushman, J.F.; Alger, T.W.

1996-07-23

122

Mass spectrometer vacuum housing and pumping system  

DOEpatents

A vacuum housing and pumping system for a portable gas chromatograph/mass spectrometer (GC/MS). The vacuum housing section of the system has minimum weight for portability while designed and constructed to utilize metal gasket sealed stainless steel to be compatible with high vacuum operation. The vacuum pumping section of the system consists of a sorption (getter) pump to remove atmospheric leakage and outgassing contaminants as well as the gas chromatograph carrier gas (hydrogen) and an ion pump to remove the argon from atmospheric leaks. The overall GC/MS system has broad application to contaminants, hazardous materials, illegal drugs, pollution monitoring, etc., as well as for use by chemical weapon treaty verification teams, due to the light weight and portability thereof.

Coutts, Gerald W. (Livermore, CA); Bushman, John F. (Oakley, CA); Alger, Terry W. (Tracy, CA)

1996-01-01

123

Variable emissivity laser thermal control system  

DOEpatents

A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.

Milner, Joseph R. (Livermore, CA)

1994-01-01

124

Dimensions of variability in embedded operating systems  

Microsoft Academic Search

Design, implementation, and re-engineering of operating systems are still an ambitious undertaking.\\u000a Despite, or even because, of the long history of theory and practice in this field, adapting existing systems\\u000a to environments of different conditions and requirements as originally specified or assumed, in terms of\\u000a functional and\\/or non-functional respects, is anything but simple. Especially this is true for the embedded

Wolfgang Schröder-preikschat; Daniel Lohmann; Fabian Scheler; Olaf Spinczyk

2007-01-01

125

A variable-collimation display system  

NASA Astrophysics Data System (ADS)

Two important human depth cues are accommodation and vergence. Normally, the eyes accommodate and converge or diverge in tandem; changes in viewing distance cause the eyes to simultaneously adjust both focus and orientation. However, ambiguity between accommodation and vergence cues is a well-known limitation in many stereoscopic display technologies. This limitation also arises in state-of-the-art full-flight simulator displays. In current full-flight simulators, the out-the-window (OTW) display (i.e., the front cockpit window display) employs a fixed collimated display technology which allows the pilot and copilot to perceive the OTW training scene without angular errors or distortions; however, accommodation and vergence cues are limited to fixed ranges (e.g., ~ 20 m). While this approach works well for long-range, the ambiguity of depth cues at shorter range hinders the pilot's ability to gauge distances in critical maneuvers such as vertical take-off and landing (VTOL). This is the first in a series of papers on a novel, variable-collimation display (VCD) technology that is being developed under NAVY SBIR Topic N121-041 funding. The proposed VCD will integrate with rotary-wing and vertical take-off and landing simulators and provide accurate accommodation and vergence cues for distances ranging from approximately 3 m outside the chin window to ~ 20 m. A display that offers dynamic accommodation and vergence could improve pilot safety and training, and impact other applications presently limited by lack of these depth cues.

Batchko, Robert; Robinson, Sam; Schmidt, Jack; Graniela, Benito

2014-03-01

126

Mass Properties for Space Systems Standards Development  

NASA Technical Reports Server (NTRS)

Current Verbiage in S-120 Applies to Dry Mass. Mass Margin is difference between Required Mass and Predicted Mass. Performance Margin is difference between Predicted Performance and Required Performance. Performance estimates and corresponding margin should be based on Predicted Mass (and other inputs). Contractor Mass Margin reserved from Performance Margin. Remaining performance margin allocated according to mass partials. Compliance can be evaluated effectively by comparison of three areas (preferably on a single sheet). Basic and Predicted Mass (including historical trend). Aggregate potential changes (threats and opportunities) which gives Mass Forecast. Mass Maturity by category (Estimated/Calculated/Actual).

Beech, Geoffrey

2013-01-01

127

Assessing the effect of Ross Sea source water mass variability on bottom waters offshore  

NASA Astrophysics Data System (ADS)

The Southern Ocean interacts with the polar atmosphere and cryosphere year-round. The active exchange of heat and freshwater among ocean, atmosphere, and cryosphere over the continental margins facilitates the rapid propagation of ongoing changes in the Antarctic environment. Oceanic boundary currents carry these signals to the abyssal layers of ocean basins farther to the north. The lack of adequate direct long-term time series of measurements at key locations along the current paths has made it difficult for oceanographers to assess fully the magnitude of change in ocean climate. To mitigate this shortcoming, we take advantage of a new volumetric ?-S census of Ross Sea waters to perform sensitivity studies of the variability in dense deep and bottom water production rates and export estimates. Inspection of historical oceanographic data combined with recent hydrographic stations in the Eastern Ross Sea already reveal long-term variability in source water mass properties that affect dense water formation. We estimate plausible temporal variabilities of inflowing water mass properties and their likely roles in changes of bottom water characteristics found further offshore along 150°W and 103°W.

Wiederwohl, C. L.; Orsi, A. H.; Johnson, G. C.; Purkey, S. G.

2009-12-01

128

Variable emissivity laser thermal control system  

DOEpatents

A laser thermal control system for a metal vapor laser maintains the wall temperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser. 8 figs.

Milner, J.R.

1994-10-25

129

Solar Forecasting System and Irradiance Variability Characterization  

E-print Network

.1 Photovoltaic Systems: Report 3 Development of data base allowing managed access to statewide PV and insolation. It also presents details of HNEI-developed statistical techniques for characterizing irradiance September 2014 HAWAI`I NATURAL ENERGY INSTITUTE School of Ocean & Earth Science & Technology ­ University

130

FTO genotype is associated with phenotypic variability of body mass index  

PubMed Central

There is evidence across several species for genetic control of phenotypic variation of complex traits1–4, such that the variance among phenotypes is genotype dependent. Understanding genetic control of variability is important in evolutionary biology, agricultural selection programmes and human medicine, yet for complex traits, no individual genetic variants associated with variance, as opposed to the mean, have been identified. Here we perform a meta-analysis of genome-wide association studies of phenotypic variation using 170,000 samples on height and body mass index (BMI) in human populations. We report evidence that the single nucleotide polymorphism (SNP) rs7202116 at the FTO gene locus, which is known to be associated with obesity (as measured by mean BMI for each rs7202116 genotype)5–7, is also associated with phenotypic variability. We show that the results are not due to scale effects or other artefacts, and find no other experiment-wise significant evidence for effects on variability, either at loci other than FTO for BMI or at any locus for height. The difference in variance for BMI among individuals with opposite homozygous genotypes at the FTO locus is approximately 7%, corresponding to a difference of 0.5 kilograms in the standard deviation of weight. Our results indicate that genetic variants can be discovered that are associated with variability, and that between-person variability in obesity can partly be explained by the genotype at the FTO locus. The results are consistent with reported FTO by environment interactions for BMI8, possibly mediated by DNA methylation9,10. Our BMI results for other SNPs and our height results for all SNPs suggest that most genetic variants, including those that influence mean height or mean BMI, are not associated with phenotypic variance, or that their effects on variability are too small to detect even with samples sizes greater than 100,000. PMID:22982992

Yang, Jian; Loos, Ruth J. F.; Powell, Joseph E.; Medland, Sarah E.; Speliotes, Elizabeth K.; Chasman, Daniel I.; Rose, Lynda M.; Thorleifsson, Gudmar; Steinthorsdottir, Valgerdur; Mägi, Reedik; Waite, Lindsay; Smith, Albert Vernon; Yerges-Armstrong, Laura M.; Monda, Keri L.; Hadley, David; Mahajan, Anubha; Li, Guo; Kapur, Karen; Vitart, Veronique; Huffman, Jennifer E.; Wang, Sophie R.; Palmer, Cameron; Esko, Tõnu; Fischer, Krista; Zhao, Jing Hua; Demirkan, Ay?e; Isaacs, Aaron; Feitosa, Mary F.; Luan, Jian’an; Heard-Costa, Nancy L.; White, Charles; Jackson, Anne U.; Preuss, Michael; Ziegler, Andreas; Eriksson, Joel; Kutalik, Zoltán; Frau, Francesca; Nolte, Ilja M.; Van Vliet-Ostaptchouk, Jana V.; Hottenga, Jouke-Jan; Jacobs, Kevin B.; Verweij, Niek; Goel, Anuj; Medina-Gomez, Carolina; Estrada, Karol; Bragg-Gresham, Jennifer Lynn; Sanna, Serena; Sidore, Carlo; Tyrer, Jonathan; Teumer, Alexander; Prokopenko, Inga; Mangino, Massimo; Lindgren, Cecilia M.; Assimes, Themistocles L.; Shuldiner, Alan R.; Hui, Jennie; Beilby, John P.; McArdle, Wendy L.; Hall, Per; Haritunians, Talin; Zgaga, Lina; Kolcic, Ivana; Polasek, Ozren; Zemunik, Tatijana; Oostra, Ben A.; Junttila, M. Juhani; Grönberg, Henrik; Schreiber, Stefan; Peters, Annette; Hicks, Andrew A.; Stephens, Jonathan; Foad, Nicola S.; Laitinen, Jaana; Pouta, Anneli; Kaakinen, Marika; Willemsen, Gonneke; Vink, Jacqueline M.; Wild, Sarah H.; Navis, Gerjan; Asselbergs, Folkert W.; Homuth, Georg; John, Ulrich; Iribarren, Carlos; Harris, Tamara; Launer, Lenore; Gudnason, Vilmundur; O’Connell, Jeffrey R.; Boerwinkle, Eric; Cadby, Gemma; Palmer, Lyle J.; James, Alan L.; Musk, Arthur W.; Ingelsson, Erik; Psaty, Bruce M.; Beckmann, Jacques S.; Waeber, Gerard; Vollenweider, Peter; Hayward, Caroline; Wright, Alan F.; Rudan, Igor; Groop, Leif C.; Metspalu, Andres; Khaw, Kay Tee; van Duijn, Cornelia M.; Borecki, Ingrid B.; Province, Michael A.; Wareham, Nicholas J.; Tardif, Jean-Claude; Huikuri, Heikki V.; Cupples, L. Adrienne; Atwood, Larry D.; Fox, Caroline S.; Boehnke, Michael; Collins, Francis S.; Mohlke, Karen L.; Erdmann, Jeanette; Schunkert, Heribert; Hengstenberg, Christian; Stark, Klaus; Lorentzon, Mattias; Ohlsson, Claes; Cusi, Daniele; Staessen, Jan A.; Van der Klauw, Melanie M.; Pramstaller, Peter P.; Kathiresan, Sekar; Jolley, Jennifer D.; Ripatti, Samuli; Jarvelin, Marjo-Riitta; de Geus, Eco J. C.; Boomsma, Dorret I.; Penninx, Brenda; Wilson, James F.; Campbell, Harry; Chanock, Stephen J.; van der Harst, Pim; Hamsten, Anders; Watkins, Hugh; Hofman, Albert; Witteman, Jacqueline C.; Zillikens, M. Carola; Uitterlinden, André G.; Rivadeneira, Fernando; Zillikens, M. Carola; Kiemeney, Lambertus A.; Vermeulen, Sita H.; Abecasis, Goncalo R.; Schlessinger, David; Schipf, Sabine; Stumvoll, Michael; Tönjes, Anke; Spector, Tim D.; North, Kari E.; Lettre, Guillaume; McCarthy, Mark I.; Berndt, Sonja I.; Heath, Andrew C.; Madden, Pamela A. F.; Nyholt, Dale R.; Montgomery, Grant W.; Martin, Nicholas G.; McKnight, Barbara; Strachan, David P.; Hill, William G.; Snieder, Harold; Ridker, Paul M.; Thorsteinsdottir, Unnur; Stefansson, Kari; Frayling, Timothy M.; Hirschhorn, Joel N.; Goddard, Michael E.; Visscher, Peter M.

2013-01-01

131

New RR Lyrae variables in binary systems  

NASA Astrophysics Data System (ADS)

Despite their importance, very few RR Lyrae (RRL) stars have been known to reside in binary systems. We report on a search for binary RRL in the OGLE-III Galactic bulge data. Our approach consists in the search for evidence of the light-travel time effect in so-called observed minus calculated (O-C) diagrams. Analysis of 1952 well-observed fundamental-mode RRL in the OGLE-III data revealed an initial sample of 29 candidates. We used the recently released OGLE-IV data to extend the baselines up to 17 yr, leading to a final sample of 12 firm binary candidates. We provide O-C diagrams and binary parameters for this final sample, and also discuss the properties of eight additional candidate binaries whose parameters cannot be firmly determined at present. We also estimate that ? 4 per cent of the RRL reside in binary systems.

Hajdu, G.; Catelan, M.; Jurcsik, J.; Dékány, I.; Drake, A. J.; Marquette, J.-B.

2015-04-01

132

Improving the sensitivity of stop searches with on-shell constrained invariant mass variables  

E-print Network

The search for light stops is of paramount importance, both in general as a promising path to the discovery of beyond the standard model physics and more specifically as a way of evaluating the success of the naturalness paradigm. While the LHC experiments have ruled out much of the relevant parameter space, there are "stop gaps", i.e., values of sparticle masses for which existing LHC analyses have relatively little sensitivity to light stops. We point out that techniques involving on-shell constrained M_2 variables can do much to enhance sensitivity in this region and hence help close the stop gaps. We demonstrate the use of these variables for several benchmark points and describe the effect of realistic complications, such as detector effects and combinatorial backgrounds, in order to provide a useful toolkit for light stop searches in particular, and new physics searches at the LHC in general.

Won Sang Cho; James S. Gainer; Doojin Kim; Konstantin T. Matchev; Filip Moortgat; Luc Pape; Myeonghun Park

2014-11-03

133

Variability of local PM10 mass concentrations in connection with blocking air circulation  

NASA Astrophysics Data System (ADS)

The aim of this paper is to analyze the temporal variability of Particulate Matter mass concentrations in connection with air circulation, for eight rural sites situated in the Central and Eastern parts of Europe. The stations from Poland, Hungary and Romania are rural stations without sources of pollutants. The analysis covers four winters, between December 2004 and February 2008. The pollution episodes were selected to explain air circulation influence. The results show that the causes of pollution were local, due to high mean sea level pressure and the blocking, as air circulation on large scale, was dominant in the cases of enhanced pollution in the selected area.

?tefan, Sabina; Roman, Iuliana

2015-01-01

134

A new line element derived from the variable rest mass in gravitational field  

E-print Network

This paper presents a new line element based on the assumption of the variable rest mass in gravitational field, and explores some its implications. This line element is not a vacuum solution of Einstein's equations, yet it is sufficiently close to Schwarzschild's line element to be compatible with all of the experimental and observational measurements made so far to confirm the three Einstein's predictions. The theory allows radiation and fast particles to escape from all massive bodies, even from those that in Einstein's general relativity framework will be black holes. The striking feature of this line element is the non-existence of black holes.

N. Ben-Amots

2008-08-19

135

Fractal variability: An emergent property of complex dissipative systems  

NASA Astrophysics Data System (ADS)

The patterns of variation of physiologic parameters, such as heart and respiratory rate, and their alteration with age and illness have long been under investigation; however, the origin and significance of scale-invariant fractal temporal structures that characterize healthy biologic variability remain unknown. Quite independently, atmospheric and planetary scientists have led breakthroughs in the science of non-equilibrium thermodynamics. In this paper, we aim to provide two novel hypotheses regarding the origin and etiology of both the degree of variability and its fractal properties. In a complex dissipative system, we hypothesize that the degree of variability reflects the adaptability of the system and is proportional to maximum work output possible divided by resting work output. Reductions in maximal work output (and oxygen consumption) or elevation in resting work output (or oxygen consumption) will thus reduce overall degree of variability. Second, we hypothesize that the fractal nature of variability is a self-organizing emergent property of complex dissipative systems, precisely because it enables the system's ability to optimally dissipate energy gradients and maximize entropy production. In physiologic terms, fractal patterns in space (e.g., fractal vasculature) or time (e.g., cardiopulmonary variability) optimize the ability to deliver oxygen and clear carbon dioxide and waste. Examples of falsifiability are discussed, along with the need to further define necessary boundary conditions. Last, as our focus is bedside utility, potential clinical applications of this understanding are briefly discussed. The hypotheses are clinically relevant and have potential widespread scientific relevance.

Seely, Andrew J. E.; Macklem, Peter

2012-03-01

136

Evaluation of Small Mass Spectrometer Systems  

NASA Technical Reports Server (NTRS)

This work is aimed at understanding the aspects of designing a miniature mass spectrometer (MS) system. A multitude of commercial and government sectors, such as the military, environmental agencies and industrial manufacturers of semiconductors, refrigerants, and petroleum products, would find a small, portable, rugged and reliable MS system beneficial. Several types of small MS systems are evaluated and discussed, including linear quadrupole, quadrupole ion trap, time of flight and sector. The performance of each system in terms of accuracy, precision, limits of detection, response time, recovery time, scan rate, volume and weight is assessed. A performance scale is setup to rank each systems and an overall performance score is given to each system. All experiments involved the analysis of hydrogen, helium, oxygen and argon in a nitrogen background with the concentrations of the components of interest ranging from 0-5000 part-per-million (ppm). The relative accuracies of the systems vary from < 1% to approx. 40% with an average below 10%. Relative precisions varied from 1% to 20%, with an average below 5%. The detection limits had a large distribution, ranging from 0.2 to 170 ppm. The systems had a diverse response time ranging from 4 s to 210 s as did the recovery time with a 6 s to 210 s distribution. Most instruments had scan times near, 1 s, however one instrument exceeded 13 s. System weights varied from 9 to 52 kg and sizes from 15 x 10(exp 3)cu cm to 110 x 10(exp 3) cu cm.

Arkin, C. Richard; Griffin, Timothy P.; Ottens, Andrew K.; Diaz, Jorge A.; Follistein, Duke W.; Adams, Fredrick W.; Helms, William R.; Voska, N. (Technical Monitor)

2002-01-01

137

Variable structure approach power compensation system design of an automatic carrier landing system  

Microsoft Academic Search

The design problem of approach power compensation system via variable structure control theory is considered. The function of approach power compensation system in automatic carrier landing system is introduced, and its working principle is analyzed. The approach power compensation system is designed via variable structure control theory and the ability of this system that reduces the influence of air disturbance

Zhu Qi-dan; Wang Tong; Zhang Wen; Zhou Fang

2009-01-01

138

Applications of internal translating mass technologies to smart weapons systems  

NASA Astrophysics Data System (ADS)

The field of guided projectile research has continually grown over the past several decades. Guided projectiles, typically encompassing bullets, mortars, and artillery shells, incorporate some sort of guidance and control mechanism to generate trajectory alterations. This serves to increase accuracy and decrease collateral damage. Control mechanisms for smart weapons must be able to withstand extreme acceleration loads at launch while remaining simple to reduce cost and enhance reliability. Controllable internal moving masses can be incorporated into the design of smart weapons as a mechanism to directly apply control force, to actively alter static stability in flight, and to protect sensitive components within sensor packages. This dissertation examined techniques for using internal translating masses (ITM's) for smart weapon flight control. It was first shown that oscillating a mass orthogonal to the projectile axis of symmetry generates reasonable control force in statically-stable rounds. Trade studies examined the impact of mass size, mass offset from the center of gravity, and reductions in static stability on control authority. A more detailed analysis followed in which a physical internal translating mass control mechanism was designed that minimizes force and power required using a vibrating beam as the internal moving mass. Results showed that this relatively simple mechanism provides adequate control authority while requiring low on-board power. Trade studies revealed the affect of varying beam lengths, stiffness, and damping properties. Then, the topic of static margin control through mass center modification was explored. This is accomplished by translating a mass in flight along the projectile axis of symmetry. Results showed that this system allows for greater control authority and reduced throw-off error at launch. Finally, a nonlinear sliding mode controller was designed for a projectile equipped with an internal moving mass as well as for a projectile equipped with both an ITM and canard control mechanisms. Monte Carlo simulations that incorporated realistic uncertainty demonstrated the robust nature of the control system. These dispersion simulations examined the effect of ITM size and incorporation of a variable stability mechanism. It is shown that use of an ITM as a direct control mechanism can reduce circular error probable by nearly half, while coupling ITM control with canard control can reduce required canard area by approximately half as well. Overall, it was determined that direct ITM control generates modest control authority for practical systems. Therefore, it can be used to reduce dispersion error but not eliminate it to levels commensurate with sensor noise. Likewise, the ITM variable stability mechanism provides a limited control authority enhancement to guided projectiles controlled by other means. Thus, while the mechanism may not be useful for guided munitions that exhibit ample control authority, it provides a useful supplement to projectiles requiring slight control authority improvement.

Rogers, Jonathan

139

Spatial variability of hailfalls in France: an analysis of air mass retro-trajectories  

NASA Astrophysics Data System (ADS)

Hail is the main meteorological risk in south-west France, with the strongest hailfalls being concentrated in just a few days. Specifically, this phenomenon occurs most often and with the greatest severity in the Midi-Pyrénées area. Previous studies have revealed the high spatial variability of hailfall in this part of France, even leading to different characteristics being recorded on hailpads that were relatively close together. For this reason, an analysis of the air mass trajectories was carried out at ground level and at altitude, which subsequently led to the formation of the hail recorded by these hailpads. It is already known that in the study zone, the trajectories of the storms usually stretch for long distances and are oriented towards the east, leading to hailstones with diameters in excess of 3 cm, and without any change in direction above 3 km. We analysed different days with hail precipitation where there was at least one stone with a diameter of 3 cm or larger. Using the simulations from these days, an analysis of the backward trajectories of the air masses was carried out. We used the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) to determine the origin of the air masses, and tracked them toward each of the hailpads that were hit during the day studied. The height of the final points was the height of the impacted hailpads. Similarly, the backward trajectories for different heights were also established. Finally, the results show how storms that affect neighbouring hailpads come from very different air masses; and provide a deeper understanding of the high variability that affects the characteristics of hailfalls. Acknowledgements The authors would like to thank the Regional Government of Castile-León for its financial support through the project LE220A11-2. This study was supported by the following grants: GRANIMETRO (CGL2010-15930); MICROMETEO (IPT-310000-2010-22).

Hermida, Lucía; Merino, Andrés; Sánchez, José Luis; Berthet, Claude; Dessens, Jean; López, Laura; Fernández-González, Sergio; Gascón, Estíbaliz; García-Ortega, Eduardo

2014-05-01

140

Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP was designed for the Advanced Stirling Radioisotope Generator, with a 850 °C heater head temperature. The VCHP turns on with a ?T of 30 °C, which is high enough to not risk standard ASRG operation but low enough to save most heater head life. This VCHP has a low mass, and low thermal losses for normal operation. In addition to the design, a proof-of-concept NaK VCHP was fabricated and tested. While NaK is normally not used in heat pipes, it has an advantage in that it is liquid at the reservoir operating temperature, while Na or K alone would freeze. The VCHP had two condensers, one simulating the heater head, and the other simulating the radiator. The experiments successfully demonstrated operation with the simulated heater head condenser off and on, while allowing the reservoir temperature to vary over 40 to 120 °C, the maximum range expected. In agreement with previous NaK heat pipe tests, the evaporator ?T was roughly 70 °C, due to distillation of the NaK in the evaporator.

Anderson, William G.; Tarau, Calin

2008-01-01

141

Low-Cost Automated Variable Star Detection System  

NASA Astrophysics Data System (ADS)

We propose a method of variable star detection that utilizes automated data collection with affordable equipment and analysis using open source software. Our DSLR-based camera is currently opperating at Whitman College in Walla Walla, WA. At present, it collects a wide-field image roughly every 10 minutes throughout the day and night. The system observes stars near DEC=+44 and has a magnitude limit better than 8. This system has the possibility of characterizing bright long-period variables, important since the variability of many bright stars is unknown. We present this as a proof of concept and offer guidance for the large scale cataloguing of stars, enabling undergraduate students, amateur astronomers, etc. to make a meaninful contribution to the study of variable stars.

Meades, Marin Nicole; Paust, Nathaniel

2015-01-01

142

Unstable dimension variability and synchronization of chaotic systems  

PubMed

The nonhyperbolic structure of synchronization dynamics is investigated in this work. We argue analytically and confirm numerically that the chaotic dynamics on the synchronization manifold exhibits an unstable dimension variability, which is an extreme form of nonhyperbolicity. We analyze the dynamics in the synchronization manifold and in its transversal direction, where a tonguelike structure is formed, through a system of two coupled chaotic maps. The unstable dimension variability is revealed in the statistical distribution of the finite-time transversal Lyapunov exponent, having both negative and positive values. We also point out that unstable dimension variability is a cause of severe modeling difficulty. PMID:11088481

Viana; Grebogi

2000-07-01

143

A VARIABLE FLOW CONTROL SYSTEM FOR SUBSURFACE DRIP IRRIGATION*  

Technology Transfer Automated Retrieval System (TEKTRAN)

It is important for an irrigation system to have a stable constant pressure to obtain efficient water management for crops. A simple mechanical flow control system with a pressure regulating valve was investigated for subsurface drip irrigation to maintain constant pressure under variable flow condi...

144

Modeling the Motion of an Increasing Mass System  

ERIC Educational Resources Information Center

Problems on the dynamics of changing mass systems often call for the more general form of Newton's second law Fnet = dp/dt. These problems usually involve situations where the mass of the system decreases, such as in rocket propulsion. In contrast, this experiment examines a system where the mass "increases" at a constant rate and the net force…

Kunkel, William; Harrington, Randal

2010-01-01

145

Continuous variable tangle, monogamy inequality, and entanglement sharing in Gaussian states of continuous variable systems  

E-print Network

For continuous-variable systems, we introduce a measure of entanglement, the continuous variable tangle ({\\em contangle}), with the purpose of quantifying the distributed (shared) entanglement in multimode, multipartite Gaussian states. This is achieved by a proper convex roof extension of the squared logarithmic negativity. We prove that the contangle satisfies the Coffman-Kundu-Wootters monogamy inequality in all three--mode Gaussian states, and in all fully symmetric $N$--mode Gaussian states, for arbitrary $N$. For three--mode pure states we prove that the residual entanglement is a genuine tripartite entanglement monotone under Gaussian local operations and classical communication. We show that pure, symmetric three--mode Gaussian states allow a promiscuous entanglement sharing, having both maximum tripartite residual entanglement and maximum couplewise entanglement between any pair of modes. These states are thus simultaneous continuous-variable analogs of both the GHZ and the $W$ states of three qubits: in continuous-variable systems monogamy does not prevent promiscuity, and the inequivalence between different classes of maximally entangled states, holding for systems of three or more qubits, is removed.

Gerardo Adesso; Fabrizio Illuminati

2006-02-02

146

Luminous Blue Variables are Antisocial: Their Isolation Implies they are Kicked Mass Gainers in Binary Evolution  

NASA Astrophysics Data System (ADS)

Based on their relatively isolated environments, we argue that luminous blue variables (LBVs) must be primarily the product of binary evolution, challenging the traditional single-star view wherein LBVs mark a brief transition between massive O-type stars and Wolf-Rayet (WR) stars. If the latter were true, then LBVs should be concentrated in young massive clusters like early O-type stars. This is decidedly not the case. Examining locations of LBVs in our Galaxy and the Magellanic Clouds reveals that, with few exceptions, LBVs systematically avoid clusters of O-type stars. In the Large Magellanic Cloud, LBVs are statistically much more isolated than O-type stars, and (perhaps most surprisingly) even more isolated than WR stars. This makes it impossible for LBVs to be single 'massive stars in transition' to WR stars. Instead, we propose that massive stars and supernova (SN) subtypes are dominated by bifurcated evolutionary paths in interacting binaries, wherein most WR stars and SNe Ibc correspond to the mass donors, while LBVs (and their lower-mass analogs like B[e] supergiants, which are even more isolated) are the mass gainers. In this view, LBVs are evolved massive blue stragglers. Through binary mass transfer, rejuvinated mass gainers get enriched, spun up, and sometimes kicked far from their clustered birthsites by their companion's SN. This scenario agrees better with LBVs exploding as Type IIn SNe in isolation, and it predicts that many massive runaway stars may be rapid rotators. Mergers or Thorne-Zykow objects might also give rise to LBVs, but these scenarios may have a harder time explaining why LBVs avoid clusters.

Tombleson, Ryan; Smith, Nathan

2015-01-01

147

The Barents Sea polar front and water masses variability (1980-2011)  

NASA Astrophysics Data System (ADS)

The polar front separates the warm and saline Atlantic Waters encountered in the western part of the Barents Sea from the cold and fresh Arctic Waters situated in the northern part. These water masses can mix together, mainly in the eastern part of the Barents Sea, generating dense waters in winter which can cascade into the Arctic Ocean to form the Artic Intermediate Waters. To study the interannual variability and evolution of these water masses and the fronts, we have merged data from the International Council for the Exploration of the Sea and the Arctic and Antarctic Research Institute and have built a new database which covers the period 1980-2011. The summer data is interpolated on a regular grid and a "Probability Density Function" method is used to show that the polar front splits into two branches east of 32° E where the topographic constraint weakens. Two fronts can then be defined: the "Northern Polar Front" is associated with strong salinity gradients and the "Southern Polar Front" with temperature gradients. They enclose the dense Barents Sea Water. The interannual variability of the water masses is apparent in the observed data and is linked to that of the ice cover. In contrast, the link with the Arctic Oscillation is not clear. However, results from a general circulation model suggest that such a link could be found if winter data were taken into account. A strong trend, which amplifies during the last decade, is also found: the Atlantic Water occupies a larger volume of the Barents Sea. This "Atlantification" could be accompanied by a northwards displacement of the southern polar front in the eastern part of the Barents Sea (which is suggested by a model based study) and a decrease of the volume occupied by the Arctic Waters.

Oziel, L.; Sirven, J.; Gascard, J.-C.

2015-03-01

148

Power optimization of variable voltage core-based systems  

Microsoft Academic Search

The growing class of portable systems, such as personal computing and communication devices, has resulted in a new set of system design requirements, mainly characterized by dominant importance of power minimization and design reuse. We develop the design methodology for the low power core-based real-time system-on-chip based on dynamically variable voltage hardware. The key challenge is to develop effective scheduling

Inki Hong; Darko Kirovski; Gang Qu; Miodrag Potkonjak; Mani B. Srivastava

1998-01-01

149

Electro-optic systems research using the variable parameter FLIR  

Microsoft Academic Search

An efficient and cost-effective approach to electrooptic systems research is to investigate system concepts and sensor components on a generic testbed that can be readily modified for a variety of applications. The variable-parameter FLIT is a research and development testbed for evaluating systems concepts, testing sensor components, and providing benchmark data for model and figure-of-merit validations. The authors describe the

Edward A. Watson; Fred P. Blommel; Robert A. Muse

1992-01-01

150

Solving Systems of Linear Equations in Two Variables  

NSDL National Science Digital Library

This tutorial shows students how to solve systems of linear equations in two variables using three methods: graphing, substitution, and elimination. Each method is clearly demonstrated with graphics when applicable and step-by-step instructions so students can follow along easily. In addition, links to previously-covered algebra material are embedded in the page in case students need to review prerequisite knowledge such as solving linear equations in one variable and graphing equations. The lesson is followed by three practice problems for students to tackle using each of the three methods of solving systems of linear equations.

2010-08-03

151

Interannual variability of water mass properties in the Tunisia-Sicily Channel  

NASA Astrophysics Data System (ADS)

We analysed in situ CTD data collected on 36 joint Tunisian-Italian oceanographic cruises in the Tunisia-Sicily Channel (Cap Bon-Mazara del Vallo section) from 1995 to 2009 in order to identify the water masses in the region and to estimate the interannual variability of their hydrological characteristics. Besides the well-known AW (Atlantic Water) and LIW (Levantine Intermediate Water), other water masses have been identified though their presence is neither as steady nor as stable as the aforementioned ones. The WIW (Western Intermediate Water) flows beneath the AW towards the eastern basin while the IW (Ionian Water), with a highly intermittent character, flows within the subsurface layer towards the western basin. The flow of subsurface water (WIW and IW) is affected by intense mixing which modifies the water masses, tending to make them disappear. Moreover, the same hydrological time series produced interesting results concerning the increase in both temperature and salinity in the Tunisia-Sicily Channel. This trend especially concerns the deeper layers (LIW and tEMDW, i.e. transitional Eastern Mediterranean Deep Water) and we hypothesise that this is a direct response to climatic change occurring in the eastern basin.

Ben Ismail, Sana; Schroeder, Katrin; Sammari, Chérif; Gasparini, Gian Pietro; Borghini, Mireno; Aleya, Lotfi

2014-07-01

152

Modeling the spatial variability of dispersivity to deal with anomalous mass transport in the subsurface  

NASA Astrophysics Data System (ADS)

The limitations of the classical Advection-Dispersion Equation (ADE) approach to model mass transport remain a subject of research. The term anomalous transport is usually applied when the ADE fails to reproduce real field or lab experiments tracer tests data. Some authors address this limitation using high-resolution heterogeneous hydraulic conductivity (K) fields. Besides, the non-Fickian behavior of transport is another issue addressed. However, the effects of the spatial variability of dispersivity, and the influence of the model support scale on this property, have been rarely studied. The lack of experimental knowledge on the dispersivity behavior leads to model this basic parameter as an averaged calibrated parameter highly dependent on the model discretization size. In order to study the local behavior of the dispersivity a porous medium tank was designed and built at the Technical University of Valencia (Spain). This paper presents new results and conclusions obtained from the experiments conducted in this lab prototype. The steady flow through the porous medium tank lab is quasi-2D, and the K field imitates the patterns of spatial variability found in a real and highly heterogeneous formation (MADE2 site). The tracer tests are run using a conservative dye tracer and the tank is monitored by a grid of pressure transducers and taking digital images that are processed to map the evolution of solute concentrations in the tank. The set of exhaustive head and concentration data is used to compute detail local information of the effective dispersivity field at different time steps, and at different support scales. The analysis of results shows that the dispersivity field displays patterns of spatial variability related with the physical nature of the local material and also with the local evolution of concentrations at every grid block. We have found that the anomalous transport behavior observed in the lab tank can be accurately modeled using the classical ADE if the dispersivity field identified from the lab measurements is used. However, we have also obtained high-resolution K fields by inverse stochastic modeling, and have been able to reproduce experimental data using these K fields with average dispersivity data. This result apparently shows there are to alternative approaches based on the spatial variability of K field or dispersivity field. It happens that mathematically the latter parameter might be derived from the variability of K. However, we show the convenience of modeling both dispersivity and K variability.

Capilla, J. E.; Sanchez Fuster, I.; Sanchez Barrero, L.

2012-12-01

153

Numerical simulation of a variable speed refrigeration system  

Microsoft Academic Search

This work presents two numerical models to simulate the transient and steady state behavior of a vapor compression refrigeration system. The condenser and the evaporator were divided into a number of control volumes. Time dependent partial differential equations system was obtained from the mass, energy and momentum balances for each control volume. As the expansion valve and the compressor both

R. N. N. Koury; L. Machado; K. A. R. Ismail

2001-01-01

154

Parsing with logical variables (logic-based programming systems)  

SciTech Connect

Logic based programming systems have enjoyed an increasing popularity in applied AI work in the last few years. One of the contributions to computational linguistics made by the logic programming paradigm has been the definite clause grammar. In comparing DCGS with previous parsing mechanisms such as ATNS, certain clear advantages are seen. The authors feel that the most important of these advantages are due to the use of logical variables with unification as the fundamental operation on them. To illustrate the power of the logical variable, they have implemented an experimental atn system which treats atn registers as logical variables and provides a unification operation over them. They aim to simultaneously encourage the use of the powerful mechanisms available in DCGS and demonstrate that some of these techniques can be captured without reference to a resolution theorem prover. 14 references.

Finin, T.W.; Stone Palmer, M.

1983-01-01

155

Mass Uncertainty and Application For Space Systems  

NASA Technical Reports Server (NTRS)

Expected development maturity under contract (spec) should correlate with Project/Program Approved MGA Depletion Schedule in Mass Properties Control Plan. If specification NTE, MGA is inclusive of Actual MGA (A5 & A6). If specification is not an NTE Actual MGA (e.g. nominal), then MGA values are reduced by A5 values and A5 is representative of remaining uncertainty. Basic Mass = Engineering Estimate based on design and construction principles with NO embedded margin MGA Mass = Basic Mass * assessed % from approved MGA schedule. Predicted Mass = Basic + MGA. Aggregate MGA % = (Aggregate Predicted - Aggregate Basic) /Aggregate Basic.

Beech, Geoffrey

2013-01-01

156

Field Assessment of A Variable-rate Aerial Application System  

Technology Transfer Automated Retrieval System (TEKTRAN)

Several experiments were conducted to evaluate the system response of a variable-rate aerial application controller to changing flow rates. The research is collaboration between the USDA, ARS, APTRU and Houma Avionics, USA, manufacturer of a widely used flow controller designed for agricultural airc...

157

Performance evaluation of a center pivot variable rate irrigation system  

Technology Transfer Automated Retrieval System (TEKTRAN)

Variable Rate Irrigation (VRI) for center pivots offers potential to match specific application rates to non-uniform soil conditions along the length of the lateral. The benefit of such systems is influenced by the areal extent of these variations and the smallest scale to which the irrigation syste...

158

Extremal entanglement and mixedness in continuous variable systems  

Microsoft Academic Search

We investigate the relationship between mixedness and entanglement for Gaussian states of continuous variable systems. We introduce generalized entropies based on Schatten p norms to quantify the mixedness of a state and derive their explicit expressions in terms of symplectic spectra. We compare the hierarchies of mixedness provided by such measures with the one provided by the purity (defined as

Gerardo Adesso; Alessio Serafini; Fabrizio Illuminati

2004-01-01

159

Quantification and Scaling of Multipartite Entanglement in Continuous Variable Systems  

Microsoft Academic Search

We present a theoretical method to determine the multipartite entanglement between different partitions of multimode, fully or partially symmetric Gaussian states of continuous variable systems. For such states, we determine the exact expression of the logarithmic negativity and show that it coincides with that of equivalent two-mode Gaussian states. Exploiting this reduction, we demonstrate the scaling of the multipartite entanglement

Gerardo Adesso; Alessio Serafini; Fabrizio Illuminati

2004-01-01

160

Regulator valve for hydraulic control system including variable displacement pump  

Microsoft Academic Search

A hydraulic control system is described for an automotive automatic transmission comprising: an automatic transmission actuated by hydraulic fluid; a variable capacity pump for supplying hydraulic fluid under pressure for actuating the automatic transmission. The pump has a control arrangement including a control chamber which varies the capacity of the pump in response to the pressure prevailing therein. A pressure

T. Shibayama; K. Sugano

1986-01-01

161

Interannual salinity variability of the Northern Yellow Sea Cold Water Mass  

NASA Astrophysics Data System (ADS)

This paper discusses the interannual variability of the Northern Yellow Sea Cold Water Mass (NYSCWM) and the factors that influence it, based on survey data from the 1976-2006 national standard section and the Korea Oceanographic Data Center, monthly E-P flux data from the European Centre for Medium-Range Weather Forecasts, and meridional wind speed data from the International Comprehensive Ocean-Atmosphere Data Set. The results show that: 1) the mean salinity of the NYSCWM center has a slightly decreasing trend, which is not consistent with the high salinity center; 2) both the southern salinity front and the halocline of the NYSCWM display a weakening trend, which indicates that the difference between the NYSCWM and coastal water decreases; 3) the Yellow Sea Warm Current intrusion, the E-P flux of the northern Yellow Sea, and the strength of the winter monsoon will affect the NYSCWM salinity during the following summer.

Li, Ang; Yu, Fei; Diao, Xinyuan

2015-01-01

162

Variable-reluctance generators in wind-energy systems  

Microsoft Academic Search

Two methods of incorporating the variable-reluctance generator (VRG) into advanced wind conversion systems at or above the 50-kW power level are presented. Operating through a power electronic interface to the electric utility, this generator offers simplifications of the utility\\/generator interface over adjustable-speed wind conversion systems based on the induction generator. In addition, analyses performed using experimentally based data show that

David A. Torrey

1993-01-01

163

ADRC for variable valve timing system of gasoline engine  

Microsoft Academic Search

The response and disturbance rejection ability of the electro-hydraulic variable valve timing(VVT)system make great influence on the performance of gasoline engine. It is a challenge for the classical linear controller because of the nonlinear behavior of the system including the mechanical wear, oil pressure, oil temperature and engine speed. The feedforward controller and liner ADRC are proposed in this paper

Yu He; Ying Yan; Hui Xie; Zhiqiang Gao

2011-01-01

164

Mass spectrometric investigation of molecular variability of grass pollen group 1 allergens.  

PubMed

Natural grass pollen allergens exhibit a wide variety of isoforms. Precise characterization of such microheterogeneity is essential to improve diagnosis and design appropriate immunotherapies. Moreover, standardization of allergen vaccine production is a prerequisite for product safety and efficiency. Both qualitative and quantitative analytical methods are thus required to monitor and control the huge natural variability of pollens, as well as final product quality. A proteomic approach has been set up to investigate in depth the structural variability of five group 1 allergens originating from distinct grass species (Ant o 1, Dac g 1, Lol p 1, Phl p 1, and Poa p 1). Whereas group 1 is the most conserved grass pollen allergen, great variations were shown between the various isoforms found in these five species using mass spectrometry, with many amino acid exchanges, as well as variations in proline hydroxylation level and in main N-glycan motifs. The presence of O-linked pentose residues was also demonstrated, with up to three consecutive units on the first hydroxyproline of Ant o 1. In addition, species-specific peptides were identified that might be used for product authentication or individual allergen quantification. Lastly, natural or process-induced modifications (deamidation, oxidation, glycation) were evidenced, which might constitute useful indicators of product degradation. PMID:19572759

Fenaille, François; Nony, Emmanuel; Chabre, Henri; Lautrette, Aurélie; Couret, Marie-Noëlle; Batard, Thierry; Moingeon, Philippe; Ezan, Eric

2009-08-01

165

Mass Distribution and Mass Transport in the Earth System: Recent Scientific Progress Due to Interdisciplinary Research  

NASA Astrophysics Data System (ADS)

This Special Issue on "Mass Distribution and Mass Transport in the Earth System: Recent Scientific Progress due to Interdisciplinary Research" reports a number of findings resulting from a collaborative effort run from 2006 until 2013, in the framework of the DFG Priority Program 1257 "Mass Distribution and Mass Transport in the Earth System". Contributions have been arranged along five lines, i.e. (1) improvements in geodesy: satellite mass monitoring through gravimetry and altimetry, (2) applications in large-scale hydrology, (3) applications in solid Earth research, (4) applications in cryospheric research, (5) applications in ocean sciences.

Kusche, Jürgen; Klemann, Volker; Sneeuw, Nico

2014-11-01

166

Synchronization between variable time delayed systems and cryptography  

E-print Network

In this letter we consider a prototype model which is described as an autonomous continuous time delayed differential equation with just one variable. The chaos has been investigated with variable delay time and the synchronization phenomenon is examined both numerically and analytically using the Krasovskii-Lyapunov functions. We have applied adaptive coupling law for synchronization,where the coupling equation also contains delay with modulated time. We also studied the effect of cryptography for this coupled system and the message extraction procedure is illustrated with the help of simulated results.

Dibakar Ghosh; Santo Banerjee; A. Roy Chowdhury

2008-02-06

167

Hydraulic control system for continuously variable V-belt transmission  

SciTech Connect

A hydraulic control system is described for a continuously variable V-belt transmission which includes a continuously variable transmission mechanism having a drive pulley, a driven pulley and a V-belt interconnecting the drive and driven pulleys and a change-direction gearing disposed between an engine and the drive pulley to establish a forward drive path or a reverse drive path from the engine to the drive pulley, the change-direction gearing including a forward clutch and a reverse clutch.

Abo, K.; Kumura, H.; Tanaka, Y.; Hirano, H.; Yamamuro, S.

1986-04-29

168

Direct measurement of sub-surface mass change using the variable-baseline gravity gradient method  

USGS Publications Warehouse

Time-lapse gravity data provide a direct, non-destructive method to monitor mass changes at scales from cm to km. But, the effectively infinite spatial sensitivity of gravity measurements can make it difficult to isolate the signal of interest. The variable-baseline gravity gradient method, based on the difference of measurements between two gravimeters, is an alternative to the conventional approach of individually modeling all sources of mass and elevation change. This approach can improve the signal-to-noise ratio for many applications by removing the contributions of Earth tides, loading, and other signals that have the same effect on both gravimeters. At the same time, this approach can focus the support volume within a relatively small user-defined region of the subsurface. The method is demonstrated using paired superconducting gravimeters to make for the first time a large-scale, non-invasive measurement of infiltration wetting front velocity and change in water content above the wetting front.

Kennedy, Jeffrey; Ferré, Ty P. A.; Güntner, Andreas; Abe, Maiko; Creutzfeldt, Benjamin

2014-01-01

169

Nutrient characteristics of the water masses and their seasonal variability in the eastern equatorial Indian Ocean.  

PubMed

Nutrient characteristics of four water masses in the light of their thermohaline properties are examined in the eastern Equatorial Indian Ocean during winter, spring and summer monsoon. The presence of low salinity water mass with "Surface enrichments" of inorganic nutrients was observed relative to 20 m in the mixed layer. Lowest oxygen levels of 19 microM at 3 degrees N in the euphotic zone indicate mixing of low oxygen high salinity Arabian Sea waters with the equatorial Indian Ocean. The seasonal variability of nutrients was regulated by seasonally varying physical processes like thermocline elevation, meridional and zonal transport, the equatorial undercurrent and biological processes of uptake and remineralization. Circulation of Arabian Sea high salinity waters with nitrate deficit could also be seen from low N/P ratio with a minimum of 8.9 in spring and a maximum of 13.6 in winter. This large deviation from Redfield N/P ratio indicates the presence of denitrified high salinity waters with a seasonal nitrate deficit ranging from -4.85 to 1.52 in the Eastern Equatorial Indian Ocean. PMID:20547419

Sardessai, S; Shetye, Suhas; Maya, M V; Mangala, K R; Prasanna Kumar, S

2010-01-01

170

Constraining aerosol optical models using ground-based, collocated particle size and mass measurements in variable air mass regimes during the 7-SEAS/Dongsha experiment  

NASA Astrophysics Data System (ADS)

During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment (? = 550 nm) for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulfate, nitrate, and elemental carbon. Achieving full optical closure is hampered by limitations in accounting for the role of water vapor in the system, uncertainties in the instruments and the need for further knowledge in the source apportionment of the model's major chemical components. Nonetheless, our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulfate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote sensing and climate research studies in dynamic aerosol-rich environments like Dongsha.

Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Hsu, N. Christina; Lin, Neng-Huei; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

2013-10-01

171

Complex systems and the technology of variability analysis  

PubMed Central

Characteristic patterns of variation over time, namely rhythms, represent a defining feature of complex systems, one that is synonymous with life. Despite the intrinsic dynamic, interdependent and nonlinear relationships of their parts, complex biological systems exhibit robust systemic stability. Applied to critical care, it is the systemic properties of the host response to a physiological insult that manifest as health or illness and determine outcome in our patients. Variability analysis provides a novel technology with which to evaluate the overall properties of a complex system. This review highlights the means by which we scientifically measure variation, including analyses of overall variation (time domain analysis, frequency distribution, spectral power), frequency contribution (spectral analysis), scale invariant (fractal) behaviour (detrended fluctuation and power law analysis) and regularity (approximate and multiscale entropy). Each technique is presented with a definition, interpretation, clinical application, advantages, limitations and summary of its calculation. The ubiquitous association between altered variability and illness is highlighted, followed by an analysis of how variability analysis may significantly improve prognostication of severity of illness and guide therapeutic intervention in critically ill patients. PMID:15566580

Seely, Andrew JE; Macklem, Peter T

2004-01-01

172

THE MESON MASS SYSTEM PAOLO PALAZZI  

E-print Network

it in perspective it is interesting to compare the discovery timelines of atomic and particle physics. Dalton. Masses and the particle physics timeline paradox The particle mass spectrum is a mystery, and to put established the atomic nature of chemistry (1808), Mendeleyev charted the taxonomy with the periodic table

173

Mass flow considerations for solar air heating systems  

Microsoft Academic Search

This paper presents the results from a computer simulation study of the mass flow rate effect in solar air collector\\/rock bin storage systems. The results show that there can be a fairly wide range of mass flow rates in a solar air heating system over which the system's performance does not vary significantly. Two aspects of a solar air heating

T. A. Newell; S. R. Swanson; R. F. Boehm

1979-01-01

174

Movement Systems as Dynamical Systems: The Functional Role of Variability and its Implications for Sports Medicine  

Microsoft Academic Search

successfully applied to the study of movement systems, contradicting traditional views of variability as noise or error. From this perspective, it is apparent that variability in movement systems is omnipresent and unavoidable due to the distinct constraints that shape each individual's behaviour. In this position paper, it is argued that trial-to-trial movement variations within individuals and perform- ance differences observed

Keith Davids; Paul Glazier; Roger Bartlett

2003-01-01

175

Analysis of X-ray spectral variability and black hole mass determination of the NLS1 galaxy Mrk 766  

NASA Astrophysics Data System (ADS)

We present an XMM-Newton time-resolved spectral analysis of the narrow-line Seyfert 1 galaxy Mrk 766. We analysed eight available observations taken between May 2000 and June 2005 with the EPIC-pn camera in order to investigate the X-ray spectral variability produced by changes in the mass accretion rate. The 0.2 - 10 keV spectra are extracted in time bins longer than 3 ks to have at least 3 × 104 net counts in each bin and then accurately trace the variations of the best-fit parameters of our adopted Comptonization spectral model. We tested a bulk-motion Comptonization (BMC) model which is in general applicable to any physical system powered by accretion onto a compact object, and assumes that soft seed photons are efficiently up-scattered via inverse Compton scattering in a hot and dense electron corona. The Comptonized spectrum has a characteristic power law shape, whose slope was found to increase for large values of the normalization of the seed component, which is proportional to the mass accretion rate ? (in Eddington units). Our baseline spectral model also includes a warm absorber lying on the line of sight and radiation reprocessing from the accretion disc or from outflowing matter in proximity to the central compact object. Our study reveals that the normalization-slope correlation, observed in Galactic black hole sources (GBHs), also holds for Mrk 766: variations of the photon index in the range ? ~ 1.9-2.4 are indeed likely to be related to the variations of ?, as observed in X-ray binary systems. We finally applied a scaling technique based on the observed correlation to estimate the BH mass in Mrk 766. This technique is commonly and successfully applied to measure masses of GBHs, and this is the first time it has been applied in detail to estimate the BH mass in an AGN. We obtained a value of MBH = 1.26-0.77+1.00×106 M?, which is in very good agreement with that estimated by the reverberation mapping. Appendix A is available in electronic form at http://www.aanda.org

Giacchè, S.; Gilli, R.; Titarchuk, L.

2014-02-01

176

Sociotechnical systems in an age of mass customization  

Microsoft Academic Search

Sociotechnical systems theory (STS) emerged as a design tool for democratizing work in an age of mass production. How should STS be re-thought for the age of mass customization? Linking mass customization to the task of building a learning organization, this article examines the case of redesign of a chemical pilot plant whose purpose was to test new equipment and

Larry Hirschhorn; Phillip Noble; Thomas Rankin

2001-01-01

177

PRECISION PHOTOMETRIC MONITORING OF VERY LOW MASS {sigma} ORIONIS CLUSTER MEMBERS: VARIABILITY AND ROTATION AT A FEW Myr  

SciTech Connect

We present high-precision photometry on 107 variable low-mass stars and brown dwarfs in the {approx}3 Myr {sigma} Orionis open cluster. We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate members of the low-mass cluster population, from 0.02 to 0.5 M {sub sun}. We are sensitive to brightness changes on timescales from 10 minutes to two weeks with amplitudes as low as 0.004 mag, and find variability on these timescales in nearly 70% of cluster members. We identify both periodic and aperiodic modes of variability, as well as semi-periodic rapid fading events that are not accounted for by the standard explanations of rotational modulation of surface features or accretion. We have incorporated both optical and infrared color data to uncover trends in variability with mass and circumstellar disks. While the data confirm that the lowest-mass objects (M < 0.2 M {sub sun}) rotate more rapidly than the 0.2-0.5 M {sub sun} members, they do not support a direct connection between rotation rate and the presence of a disk. Finally, we speculate on the origin of irregular variability in cluster members with no evidence for disks or accretion.

Cody, Ann Marie [Cerro Tololo Inter-American Observatory (Chile); Hillenbrand, Lynne A., E-mail: amc@astro.caltech.ed [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States)

2010-12-15

178

Effect of variable body mass on plantar foot pressure and off-loading device efficacy.  

PubMed

An increasing body of evidence has implicated obesity as having a negative effect on the development, treatment, and outcome of lower extremity pathologic entities, including diabetic foot disease. The objective of the present study was to increase the body of knowledge with respect to the effects of obesity on foot function. Specifically, we attempted to (1) describe the relationship between an increasing body mass index (BMI) on plantar foot pressures during gait, and (2) evaluate the efficacy of commonly prescribed off-loading devices with an increasing BMI. A repeated measures design was used to compare the peak plantar foot pressures under multiple test conditions, with the volunteers acting as their own controls. The primary outcome measure was the mean peak plantar pressure in the heel, midfoot, forefoot, and first metatarsal, and the 2 variables were modification of patient weight (from "normal" BMI to "overweight," "obese," and "morbidly obese") and footwear (from an athletic sneaker to a surgical shoe, controlled ankle motion walker, and total contact cast). Statistically significant increases in the peak plantar pressures were observed with increasing volunteer BMI weight class, regardless of the off-loading device used. The present investigation has provided unique and specific data with respect to the changes that occur in the peak plantar pressures with variable BMIs across different anatomic levels and with commonly used off-loading devices. From our results, we have concluded that although the plantar pressures increase with increasing weight, it appears that at least some reduction in pressure can be achieved with an off-loading device, most effectively with the total contact cast, regardless of the patient's BMI. PMID:24735742

Pirozzi, Kelly; McGuire, James; Meyr, Andrew J

2014-01-01

179

Variable geometry ejectors and their applications in ejector refrigeration systems  

Microsoft Academic Search

Refrigeration and air-conditioning units powered by low-grade thermal energy have economic advantages. However, the current market is dominated by mechanical vapour-compression systems powered by electrical energy. Ejector-refrigeration cycles offer a low-cost and reliable option for harnessing low-grade thermal energy. Recent studies have shown that variable-geometry ejectors play an important role in achieving optimal performance. Unfortunately, detailed design information on these

Da-Wen Sun

1996-01-01

180

Quantification and scaling of multipartite entanglement in continuous variable systems  

E-print Network

We present a theoretical method to determine the multipartite entanglement between different partitions of multimode, fully or partially symmetric Gaussian states of continuous variable systems. For such states, we determine the exact expression of the logarithmic negativity and show that it coincides with that of equivalent two--mode Gaussian states. Exploiting this reduction, we demonstrate the scaling of the multipartite entanglement with the number of modes and its reliable experimental estimate by direct measurements of the global and local purities.

Gerardo Adesso; Alessio Serafini; Fabrizio Illuminati

2004-10-15

181

Quantification and scaling of multipartite entanglement in continuous variable systems.  

PubMed

We present a theoretical method to determine the multipartite entanglement between different partitions of multimode, fully or partially symmetric Gaussian states of continuous variable systems. For such states, we determine the exact expression of the logarithmic negativity and show that it coincides with that of equivalent two-mode Gaussian states. Exploiting this reduction, we demonstrate the scaling of the multipartite entanglement with the number of modes and its reliable experimental estimate by direct measurements of the global and local purities. PMID:15601075

Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio

2004-11-26

182

Analysis of Gravity Recovery and Climate Experiment time-variable mass redistribution signals over North America by means of principal component analysis  

NASA Astrophysics Data System (ADS)

Four years of data provided by the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE) satellite mission are analyzed over North America using principal component analysis (PCA). Three hydrology models [Global Land Data Assimilation System (GLDAS), Climate Prediction Center (CPC), and Land Dynamics (LaD)] are used to analyze the water mass changes over the same area and time period. The GRACE-observed and the hydrology models mass changes are compared spatially and temporally, and good agreement is observed. Two signal modes are found to represent more than 65% of the GRACE-observed mass variability. The first mode represents mainly mass changes related to the snow accumulation and melting and has maximum amplitude in the western Cordillera and Québec-Labrador regions. The second mode comprises long-term positive mass changes in central and eastern Canada and negative mass changes in Alaska. In addition, two more spatiotemporal patterns that explain 14% of the GRACE-observed mass variability are extracted and studied, but no definite relation to hydrology is established. While the GLDAS model agrees very well with the GRACE observations, it is found that the CPC model also provides useful information for validating the GRACE-observed mass changes in North America. On the basis of the results of this study, we can state that principal component analysis is a useful technique for extracting and validating regional hydrology signals from GRACE gravity field data. The main advantage of PCA is the capability to extract interannual and nonperiodic mass changes in addition to long-term and periodic variations.

Rangelova, E.; van der Wal, W.; Braun, A.; Sideris, M. G.; Wu, P.

2007-09-01

183

Effect of environmental variables on body size evolution of crinoids between periods of mass extinctions  

NASA Astrophysics Data System (ADS)

Body size plays a major role in determining whether or not an organism can sustain in its local environment. The ecosystem of an animal has a major effect on the fitness of organisms, and it would be interesting to note the degree to which various environmental factors alter body size. In my project, I identify three environmental factors that seem to affect body size of crinoids, marine invertebrates from phylum Echinodermata, and explore how these variables play out in the intervals between the five mass extinctions. The particular factors I study include atmospheric CO2 concentration (proxy for temperature), O2 concentration, and sea level. Although the r and p values for all of these factors were statistically insignificant to definitively make any correlation, there was a visual correlation. For O2, I noted a generally positive correlation with body size over time. CO2 trends suggested a negative correlation until the K-T boundary, but a positive correlation afterwards. Correlation with sea level was a little more complicated: correlation was positive from the start of the Phanerozoic to the Permian extinction; it turned negative until the Cretaceous-Tertiary boundary; afterwards, it again became positive. However, for all three variables, statistical values are too low to say definitively mark any correlation. Out of all three factors, CO2 levels had the highest correlation and lowest p-values in the most time intervals: from the start of the Phanerozoic to Ordovician-Silurian Extinction, from the Late Devonian to the Permian Extinction, and from the Cretaceous-Tertiary boundary to the present. When considering first differences, CO2 levels also had the highest correlation from the Permian Extinction to Triassic-Jurassic Extinction and from the Triassic-Jurassic Extinction to Cretaceous-Tertiary Extinction. Using PaleoTS, I found that body size evolution patterns either seemed to follow either an unbiased random walk (URW) or stasis in the intervals between mass extinctions. Put together, these results suggest that environmental factors may have an effect of body size, but it may be the consequence of several environmental factors in conjunction. That is a correlation between body size and an individual environmental factor is hard to determine, but several biotic and abiotic factors may work interdependently to alter body size of crinoids.

Jani, T.; Heim, N. A.; Payne, J.

2013-12-01

184

Adaptive variable structure guidance system design of a longitudinal automatic carrier landing system  

Microsoft Academic Search

The design problem of guidance system of a longitudinal automatic carrier landing system is considered. The mathematic model of the landing guidance problem is created based on the analysis of the main architecture of a longitudinal automatic carrier landing system. The landing guidance system is designed via adaptive variable structure sliding mode control theory and the stability of guidance system

Zhu Qi-dan; Wang Tong; Zhong Xun-yu; Zhou Fang

2009-01-01

185

Variability of the proton-to-electron mass ratio on cosmological scales  

E-print Network

So far the only seemingly significant indication of a cosmological variation exists for the proton-to-electron mass ratio as stated by Reinhold et al. (2006). The measured indication of variation is based on the combined analysis of H2 absorption systems in the spectra of Q0405-443 and Q0347-383 at z=2.595 and z=3.025, respectively. The high resolution data of the latter is reanalyzed in this work to examine the influence of different fitting procedures and further potential nonconformities. This analysis cannot reproduce the significance achieved by the previous detection.

Martin Wendt; Dieter Reimers

2008-03-03

186

An extended Liouville equation for variable particle number systems  

E-print Network

It is well-known that the Liouville equation of statistical mechanics is restricted to systems where the total number of particles (N) is fixed. In this paper, we show how the Liouville equation can be extended to systems where the number of particles can vary, such as in open systems or in systems where particles can be annihilated or created. A general conservation equation for an arbitrary dynamical variable is derived from the extended Liouville equation following Irving and Kirkwood's2 technique. From the general conservation equation, the particle number conservation equation is obtained that includes general terms for the annihilation or creation of particles. It is also shown that the grand canonical ensemble distribution function is a particular stationary solution of the extended Liouville equation, as required. In general, the extended Liouville equation can be used to study nonequilibrium systems where the total number of particles can vary.

Peters, M H

1998-01-01

187

Wearable depression monitoring system with heart-rate variability.  

PubMed

A wearable depression monitoring system is proposed with an application-specific system-on-chip (SoC) solution. The SoC is designed to accelerate the filtering and feature extraction of heart-rate variability (HRV) from the electrocardiogram (ECG). Thanks to the SoC solution and planar-fashionable circuit board (P-FCB), the monitoring system becomes a low-power wearable system. Its dimension is 14cm × 7cm with 5mm thickness covering the chest band for convenient usage. In addition, with 3.7V 500mAh battery, its lifetime is at least 10 hours. For user's convenience, the system is interfacing to smart phones through Bluetooth communication. With the features of the HRV and Beck depression inventory (BDI), the smart phone application trains and classifies the user's depression scale with 71% of accuracy. PMID:25570021

Roh, Taehwan; Sunjoo Hong; Hoi-Jun Yoo

2014-08-01

188

Modeling Mass in the Solar System and a Galaxy  

NSDL National Science Digital Library

In this activity, students will discover how mass is distributed in the solar system and a galaxy by using kitty litter. Students compare the distribution of mass in a solar system to the distribution of mass in a galaxy. This is Activity 6a in the "Hiddne Lives of Galaxies" information and activity booklet. It is designed for use with "The Hidden Lives of Galaxies" poster. The activity includes a student worksheet and background information for the teacher.

2012-08-03

189

Seasonal and interannual variability of glacier mass loss in southern Alaska  

NASA Astrophysics Data System (ADS)

Alaska's climate is changing and one of the most significant indications of this change has been the late 19th to early 21st century behavior of Alaskan glaciers. Over the last decade, Gravity Recovery and Climate Experiment (GRACE) gravity measurements have enabled estimates of regional ice loss trends in glaciated southern Alaska. However, higher-resolution in situ, aircraft, GPS and other satellite data are being used to study the basin-scale processes responsible for the observed broad-scale seasonal and inter-annual variability of GRACE-derived mass change. Specifically we report on the use Moderate-resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) and Fractional Snow Cover (FSC) products, at a spatial scale of 1 km or less, to document the temporal and spatial evolution of seasonal processes over a time period that includes the GRACE observations (2002 to present). We use observations of cryospheric change over the last decade as input to 3-D viscoelastic Earth models of southern Alaska. In addition to glacial changes on a variety of temporal and spatial scales, southern Alaska is tectonically active with frequent large earthquakes. The gravimetric response, as well as the rate and orientation of crustal deformation, due to relaxation processes associated with inter-annual snow/ice changes, glacier wastage on time scales of years to decades, and large earthquakes (1964 Prince William Sound, M=9.2, 2002 Denali, Mw=7.9) will be discussed.

Sauber, J. M.; Hall, D. K.; Han, S.; Luthcke, S. B.

2013-12-01

190

Electrical transmission system with variable frequency through long length cable  

SciTech Connect

In the face of its oil reserves characteristics, deep and ultra-deep exploitation have become a vital issue for Brazil. In those cases where the oil field does not have enough pressure to ensure natural oil flow from the bottom of the sea to the platform, the process will require the use of variable speed inverter-fed subsea electrical motors placed far away from the electrical energy source. This implies a new operational condition for the electric system, which is electrical energy transmission with variable frequency, through long length cable, in the subsea environment. The behavior of such systems has not yet been extensively studied, and in the face of the costs involved, careful analysis is mandatory. The paper presents a powerful simulation tool developed for the analysis of such electrical systems. The analysis is carried out in time domain. Harmonics components of voltages and currents and their effects on the system operation are analyzed. Comparison of simulated and measured results for an actual working installation is shown. Simulation results for a long length cable transmission system are discussed.

Oliveira, J.C.; Andrade, D.A.; Araujo, S.C.N. [Univ. Federal de Uberlandia (Brazil); Paulsen, R.J.; Amaral, M.A. [Petrobras A/S, Rio de Janeiro (Brazil)

1996-12-31

191

Mass balance and exergy analysis of a fast pyrolysis system  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mass balance closure and exergetic efficiency is evaluated for a bench scale fast pyrolysis system. The USDA Agricultural Research Service (ARS) has developed this system for processing energy crops and agricultural residues for bio-oil (pyrolysis oil or pyrolysis liquids) production. Mass balance c...

192

Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES)  

NASA Astrophysics Data System (ADS)

We present the first results from a legacy project of the SMA: Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES). The MASSES project surveys a complete sample of all 73 known protostars in the Perseus molecular cloud complex, with both dust continuum and molecular line observations in a variety of dense gas and outflow tracers. The goal of the project is to understand how stars gain their mass through core and disk fragmentation, the formation and evolution of protostellar disks, and outflow-regulated mass accretion. The survey is complementary to a VLA protostar survey with dust continuum (Tobin et al, in prep), which shows a high fraction of multiple protostars. With this larger, unbiased sample and better sensitivity, MASSES will build on results from previous protostar surveys to discern evolutionary trends and to provide a better understanding of the stellar mass assembly process.

Lee, Katherine I.; Dunham, Michael; Myers, Philip C.; Kristensen, Lars; Goodman, Alyssa A.; Bourke, Tyler L.; Tobin, John J.; Pineda, Jaime E.; Jorgensen, Jes; Arce, Hector G.; Offner, Stella; Vorobyov, Eduard

2015-01-01

193

Extremal entanglement and mixedness in continuous variable systems  

E-print Network

We investigate the relationship between mixedness and entanglement for Gaussian states of continuous variable systems. We introduce generalized entropies based on Schatten $p$-norms to quantify the mixedness of a state, and derive their explicit expressions in terms of symplectic spectra. We compare the hierarchies of mixedness provided by such measures with the one provided by the purity (defined as ${\\rm tr} \\varrho^2$ for the state $\\varrho$) for generic $n$-mode states. We then review the analysis proving the existence of both maximally and minimally entangled states at given global and marginal purities, with the entanglement quantified by the logarithmic negativity. Based on these results, we extend such an analysis to generalized entropies, introducing and fully characterizing maximally and minimally entangled states for given global and local generalized entropies. We compare the different roles played by the purity and by the generalized $p$-entropies in quantifying the entanglement and the mixedness of continuous variable systems. We introduce the concept of average logarithmic negativity, showing that it allows a reliable quantitative estimate of continuous variable entanglement by direct measurements of global and marginal generalized $p$-entropies.

Gerardo Adesso; Alessio Serafini; Fabrizio Illuminati

2004-06-09

194

Extremal entanglement and mixedness in continuous variable systems  

SciTech Connect

We investigate the relationship between mixedness and entanglement for Gaussian states of continuous variable systems. We introduce generalized entropies based on Schatten p norms to quantify the mixedness of a state and derive their explicit expressions in terms of symplectic spectra. We compare the hierarchies of mixedness provided by such measures with the one provided by the purity (defined as tr {rho}{sup 2} for the state {rho}) for generic n-mode states. We then review the analysis proving the existence of both maximally and minimally entangled states at given global and marginal purities, with the entanglement quantified by the logarithmic negativity. Based on these results, we extend such an analysis to generalized entropies, introducing and fully characterizing maximally and minimally entangled states for given global and local generalized entropies. We compare the different roles played by the purity and by the generalized p entropies in quantifying the entanglement and the mixedness of continuous variable systems. We introduce the concept of average logarithmic negativity, showing that it allows a reliable quantitative estimate of continuous variable entanglement by direct measurements of global and marginal generalized p entropies.

Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio [Dipartimento di Fisica 'E. R. Caianiello', Universita di Salerno, INFM UdR di Salerno, INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, 84081 Baronissi, SA (Italy)

2004-08-01

195

Two-Stage Variable Sample-Rate Conversion System  

NASA Technical Reports Server (NTRS)

A two-stage variable sample-rate conversion (SRC) system has been pro posed as part of a digital signal-processing system in a digital com munication radio receiver that utilizes a variety of data rates. The proposed system would be used as an interface between (1) an analog- todigital converter used in the front end of the receiver to sample an intermediatefrequency signal at a fixed input rate and (2) digita lly implemented tracking loops in subsequent stages that operate at v arious sample rates that are generally lower than the input sample r ate. This Two-Stage System would be capable of converting from an input sample rate to a desired lower output sample rate that could be var iable and not necessarily a rational fraction of the input rate.

Tkacenko, Andre

2009-01-01

196

Time-variable aliasing effects of ocean tides, atmosphere, and continental water mass on monthly mean GRACE gravity field  

Microsoft Academic Search

The Gravity Recovery and Climate Experiment (GRACE) satellite mission will provide new measurements of Earth's static and time-variable gravity fields with monthly resolution. The temporal effects due to ocean tides and atmospheric mass redistribution are assumed known and could be removed using current models. In this study we quantify the aliasing effects on monthly mean GRACE gravity estimates due to

Shin-Chan Han; Christopher Jekeli; C. K. Shum

2004-01-01

197

Study of hydromagnetic heat and mass transfer flow over an inclined heated surface with variable viscosity and electric conductivity  

Microsoft Academic Search

The effects of variable electric conductivity and temperature dependent viscosity on hydromagnetic heat and mass transfer flow along a radiate isothermal inclined permeable surface in a stationary fluid in the presence of internal heat generation (or absorption) are analyzed numerically presenting local similarity solutions for various values of the physical parameters. The research shows that the difference in the results

Mohammad M. Rahman; K. M. Salahuddin

2010-01-01

198

Realtime Multichannel System for Beat to Beat QT Interval Variability  

NASA Technical Reports Server (NTRS)

The measurement of beat-to-beat QT interval variability (QTV) shows clinical promise for identifying several types of cardiac pathology. However, until now, there has been no device capable of displaying, in real time on a beattobeat basis, changes in QTV in all 12 conventional leads in a continuously monitored patient. While several software programs have been designed to analyze QTV, heretofore, such programs have all involved only a few channels (at most) and/or have required laborious user interaction or offline calculations and postprocessing, limiting their clinical utility. This paper describes a PC-based ECG software program that in real time, acquires, analyzes and displays QTV and also PQ interval variability (PQV) in each of the eight independent channels that constitute the 12lead conventional ECG. The system also processes certain related signals that are derived from singular value decomposition and that help to reduce the overall effects of noise on the realtime QTV and PQV results.

Starc, Vito; Schlegel, Todd T.

2006-01-01

199

Variability of Carbon-IV Emission and Multi-Epoch Virial Mass Estimation in High-Redshift Quasars  

NASA Astrophysics Data System (ADS)

The CIV emission line in quasar spectra is well-known to show systematic blue-shifts often attributed to accretion disk winds. We investigate the variability of the CIV line properties in a large sample of multi-epoch quasar observations from the SDSS DR11 BOSS survey, focusing on potential correlations of the blueshift variability with line and continuum properties. Preliminary findings show very weak to no variability in the blue-shifting of the region of interest and weak correlation between line blue-shift and change in continuum flux between epochs, indicating near constant outflow speeds. We will also continue to investigate the use of multiple epoch luminosities of the CIV line as a probe of virial mass of the host SMBH. By recalibrating estimates built on the use of single epoch data and correcting for any changes in outflow speed, it is hoped to more finely tune BH mass estimates.

Sharma, Ramon; Ruan, John J.

2015-01-01

200

Variable flow -- the quest for system energy efficiency  

SciTech Connect

Varying condenser water flow has long been used as a method of controlling head pressure in water-cooled refrigeration systems. This method of head pressure control has been applied successfully on systems with scroll, reciprocating, heli-rotor, and centrifugal compressors. Condenser water flow is altered either by bypassing the condenser via a three-way valve or by throttling flow with a two-way valve. Today, the affordability and potential energy savings of adjustable speed drives makes this the preferred method of varying flow. In the quest for greater energy savings, many designers propose to vary the flow of water through the evaporators of chillers also. This feat is not as easily accomplished as the first. There are system designs that allow variable flow of chilled water at the system level while maintaining constant flow through the chiller evaporator. Yet in spite of the risk and the presence of other variable options, some still wish to vary the flow of chilled water through the evaporator by large proportions. Can it be done? Of course! However, there are a few engineering problems that must be tackled to accomplish this feat. This paper delineates those problems.

Eppelheimer, D.M. [Trane Co., LaCrosse, WI (United States)

1996-12-31

201

High Performance Variable Speed Drive System and Generating System with Doubly Fed Machines  

Microsoft Academic Search

Doubly fed machines are another alternative for variable speed drive systems. The doubly fed machines, including doubly fed induction machine, self-cascaded induction machine and doubly excited brushless reluctance machine, have several attractive advantages for variable speed drive applications, the most important one being the significant cost reduction with a reduced power converter rating. With a better understanding, improved machine design,

Yifan Tang

1994-01-01

202

MEASURING THE MASS OF SOLAR SYSTEM PLANETS USING PULSAR TIMING  

SciTech Connect

High-precision pulsar timing relies on a solar system ephemeris in order to convert times of arrival (TOAs) of pulses measured at an observatory to the solar system barycenter. Any error in the conversion to the barycentric TOAs leads to a systematic variation in the observed timing residuals; specifically, an incorrect planetary mass leads to a predominantly sinusoidal variation having a period and phase associated with the planet's orbital motion about the Sun. By using an array of pulsars (PSRs J0437-4715, J1744-1134, J1857+0943, J1909-3744), the masses of the planetary systems from Mercury to Saturn have been determined. These masses are consistent with the best-known masses determined by spacecraft observations, with the mass of the Jovian system, 9.547921(2) x10{sup -4} M {sub sun}, being significantly more accurate than the mass determined from the Pioneer and Voyager spacecraft, and consistent with but less accurate than the value from the Galileo spacecraft. While spacecraft are likely to produce the most accurate measurements for individual solar system bodies, the pulsar technique is sensitive to planetary system masses and has the potential to provide the most accurate values of these masses for some planets.

Champion, D. J.; Hobbs, G. B.; Manchester, R. N.; Edwards, R. T.; Burke-Spolaor, S.; Sarkissian, J. M. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Backer, D. C. [Department of Astronomy and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720 (United States); Bailes, M.; Bhat, N. D. R.; Van Straten, W. [Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia); Coles, W. [Electrical and Computer Engineering, University of California at San Diego, La Jolla, CA (United States); Demorest, P. B. [National Radio Astronomy Observatory, Charlottesville, VA 22901 (United States); Ferdman, R. D.; Purver, M. B. [Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL (United Kingdom); Folkner, W. M. [Jet Propulsion Laboratory, 4800 Oak Grove Dr, Pasadena, CA 91109-8099 (United States); Hotan, A. W. [Curtin Institute of Radio Astronomy, Curtin University, Bentley, WA 6102 (Australia); Kramer, M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Lommen, A. N. [Franklin and Marshall College, 415 Harrisburg Pike, Lancaster, PA 17604 (United States); Nice, D. J. [Physics Department, Lafayette College, Easton, PA 18042 (United States); Stairs, I. H., E-mail: champion@pulsarastronomy.ne [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)

2010-09-10

203

Design of a variable-focal-length optical system  

NASA Technical Reports Server (NTRS)

Requirements to place an entire optical system with a variable focal length ranging from 20 to 200 cm within a overall length somewhat less than 100 cm placed severe restrictions on the design of a zoom lens suitable for use on a comet explorer. The requirements of a wavelength range of 0.4 to 1.0 microns produced even greater limitations on the possibilities for a design that included a catadioptric (using mirrors and glass) front and followed by a zooming refractive portion. Capabilities available commercial zoom lenses as well as patents of optical systems are reviewed. Preliminary designs of the refractive optics zoom lens and the catadioptric system are presented and evaluated. Of the two, the latter probably has the best chance of success, so long as the shortest focal lengths are not really needed.

Ricks, D.; Shannon, R. R.

1984-01-01

204

VX Her: Eclipsing Binary System or Single Variable Star  

NASA Astrophysics Data System (ADS)

VX Her is a pulsating variable star with a period of .4556504 days. It is believed to be part of an eclipsing binary system (Fitch et al. 1966). This hypothesis originated from Fitch seeing VX Her's minimum point on its light curve reaching a 0.7 magnitude fainter than normal and remaining that way for nearly two hours. If VX Her were indeed a binary system, I would expect to see similar results with a fainter minimum and a broader, more horizontal dip. Having reduced and analyzed images from the Southeastern Association for Research in Astronomy Observatory in Chile and Kitt Peak, as well as images from a 0.15m reflector at East Tennessee State University, I found that VX Her has the standard light curve of the prototype variable star, RR Lyrae. Using photometry, I found no differing features in its light curve to suggest that it is indeed a binary system. However, more observations are needed in case VX Her is a wide binary.

Perry, Kathleen; Castelaz, Michael; Henson, Gary; Boghozian, Andrew

2015-01-01

205

Time-Variable Gravity Signal due to Extratropic Pacific Water Mass Redistribution  

NASA Technical Reports Server (NTRS)

Using the satellite-laser-ranging (SLR) data, Cox and Chao [2002] reported the detection of a large post-1998 anomaly (in the form of a positive jump) in the time series of Earth s lowest-degree gravity harmonic 52, or the dynamic oblateness. Among several groups now examining the mass redistribution in the global geophysical fluids in search of the cause(s), we report here a temporally coinciding anomalies found in the extratropic north + south Pacific basins. Clearly seen in the leading EOFPC mode for extratropic Pacific, these anomalies occurred in sea-surface height, sea-surface temperature, and temperature- and salinity-depth profiles. We based our analysis on two different data sources: TOPEX/Poseidon altimetry, and the ECCO ocean general circulation model output assimilating T/P data. The magnitude of these changes, when converted to equivalent J2 change, appears to be a few times too small to explain the observed J2 directly. These findings, and the fact that the anomalies occurred following the strong 1997-98 El Nino, suggest strong geophysical connection of the interannual-to-decadal variation of 52 with the Pacific Decadal Oscillation (PDO) and the ultimate global-change processes that cause PDO. More work is underway, and additional independent data sources are examined, paying close attention to the fact that the J2 anomaly has been reversing back to normal since 2001. These include: (1) cryospheric contributions (melting of glaciers and ice sheets); (2) land hydrological contributions; (3) polar sea influences ( e g , via deep flow); (4) fluid flow in Earth's core; (5) time-variable gravity signals from SLR in higher harmonic degree/order, including J3,J4, (2,1), and (2,2) coefficients, considering their lower signal-to-noise ratios; (6) Earth rotation data in terms of length-of-day and polar motion.

Chao, B. F.; Boy, J. -P.; Cox, C. M.; Au, A. Y.

2003-01-01

206

Glacier Area and Mass Variability in the Wind River Range (Wyoming, USA): 2006 to 2012  

NASA Astrophysics Data System (ADS)

The Wind River Range (WRR) is a continuous mountain range approximately 160 km in length in west-central Wyoming, USA. The Wind River Range is host to roughly 680 snow and ice bodies with 63 of these considered glaciers including seven of the ten largest glaciers in the American Rocky Mountains. The presence of glaciers results in meltwater contributions to streamflow during the late summer (July, August, and September - JAS) when snowmelt is decreasing, temperatures are high, precipitation is low, and irrigation demand peaks. Most studies indicate that the glaciers in the Wind River Range have been retreating since the 1850's, the approximate end of the Little Ice Age. Thus, the quantification of glacier meltwater (e.g., volume, mass) contributions to late-summer/early-fall streamflow is important given this resource is dwindling due to glacier recession. In this study, we selected glaciers in the WRR and obtained satellite products of study region. The ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Level 1B imageries which are at 15 m spatial resolution between 2006~2012 were classified using supervised method and the glacier boundaries were extracted for tracking their changes. By combining ASTER L1B imageries of different years with two remote sensing derived DEM (Digital Elevation Model) datasets: ASTER GDEM (ASTER Global Digital Elevation), which is at 30 m spatial resolution and acquired prior to 2006 and Global Multi-resolution Terrain Elevation Data (GMTED 2010) which is at 250 m, 500 m and 1 km, and acquired in 2010, the 3D-view glacier volumetric loss extent could also be mapped and quantified. Assessing glacier area and volume variability is very important for evaluating and predicting glacier change in response to a changing environment.

Maloof, A.; Fang, B.; Tootle, G. A.; Lakshmi, V.; Kerr, G.

2013-12-01

207

Screening of Different Media and Substrates for Cultural Variability and Mass Culture of Arthrobotrys dactyloides Drechsler  

PubMed Central

Variability in growth and sporulation of five isolates of Arthrobotrys dactyloides was studied on five agar, 6 bran and 5 grain media. Potato dextrose agar (PDA) supported maximum growth of isolate A, C and E, while growth of isolate B and D was significantly lower on this medium. On Czapek's agar and yeast glucose agar media the differentiation in the isolates in relation to growth was poor than PDA. The other two media showed much poorer differentiation. On Czapek's agar medium, sporulation was recorded in isolate B only, whereas other isolates showed rare sporulation. Among the bran media, pea bran agar medium supported maximum growth of all the isolates except isolate B. Gram and rice bran agar media were next best. However, the growth of isolate B on the gram bran agar medium was more or less equal as other isolates. On pigeon pea bran agar medium, isolate E failed to grow while other isolates recorded poor growth. On lentil bran agar medium, only isolate B and D recorded little growth, whereas other isolates failed to grow. All the isolates recorded good sporulation on bran agar media except pigeon pea and lentil bran agar media. The grain agar media supported moderate to very good growth of all the isolates. In general isolate B remained slow growing on these media except gram grain and sorghum grain agar media on which growth of this isolate was comparable to other isolates. Sporulation in general, was good on all the grain agar media. Among different substrates screened, barley grain and pea bran were found superior to others for mass culture of isolate A of A. dactyloides. PMID:24049504

Kumar, D.; Jaiswal, R. K.

2005-01-01

208

Year-to-year variability in haemoglobin mass response to two altitude training camps  

PubMed Central

Aim To quantify the year-to-year variability of altitude-induced changes in haemoglobin mass (Hbmass) in elite team-sport athletes. Methods 12 Australian-Footballers completed a 19-day (ALT1) and 18-day (ALT2) moderate altitude (?2100?m), training camp separated by 12?months. An additional 20 participants completed only one of the two training camps (ALT1 additional n=9, ALT2 additional n=11). Total Hbmass was assessed using carbon monoxide rebreathing before (PRE), after (POST1) and 4?weeks after each camp. The typical error of Hbmass for the pooled data of all 32 participants was 2.6%. A contemporary statistics analysis was used with the smallest worthwhile change set to 2% for Hbmass. Results POST1 Hbmass was very likely increased in ALT1 (3.6±1.6%, n=19; mean±?90 CL) as well as ALT2 (4.4±1.3%, n=23) with an individual responsiveness of 1.3% and 2.2%, respectively. There was a small correlation between ALT1 and ALT2 (R=0.21, p=0.59) for a change in Hbmass, but a moderately inverse relationship between the change in Hbmass and initial relative Hbmass (g/kg (R=?0.51, p=0.04)). Conclusions Two preseason moderate altitude camps 1?year apart yielded a similar (4%) mean increase in Hbmass of elite footballers, with an individual responsiveness of approximately half the group mean effect, indicating that most players gained benefit. Nevertheless, the same individuals generally did not change their Hbmass consistently from year to year. Thus, a ‘responder’ or ‘non-responder’ to altitude for Hbmass does not appear to be a fixed trait. PMID:24282208

McLean, Blake D; Buttifant, David; Gore, Christopher J; White, Kevin; Kemp, Justin

2013-01-01

209

Digital simulation by partitioning and uncoupling the system model. [state variable representation of spacecraft control systems  

NASA Technical Reports Server (NTRS)

The present work reviews state variable simulation and then proposes a technique for simulation of nonlinear time varying systems by partitioning the system state variable model and uncoupling the resulting subsystem models so that the linear time-invariant ones can be simulated by state variable solution. Computational requirements and computer time are shown to be reduced. The method does, however, introduce an integration error due to the treatment of the intercoupling terms between the subsystems as inputs which are assumed constant over a computation interval. A fictitious sampler is thereby introduced, which is then derived in the form of a state variable error model. The application of this method in a simulation error analysis for a Saturn V attitude control system model and the simulation of a detailed nonlinear, single-axis model of the LST fine pointing control system is described.

Henson, T. F.; Womack, B. F.

1974-01-01

210

An extrasolar planetary system with three Neptune-mass planets  

Microsoft Academic Search

Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called `hot Neptunes' or `super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15days. Here we report a system of three Neptune-mass planets with periods of 8.67,

Christophe Lovis; Michel Mayor; Francesco Pepe; Yann Alibert; Willy Benz; François Bouchy; Alexandre C. M. Correia; Jacques Laskar; Christoph Mordasini; Didier Queloz; Nuno C. Santos; Stéphane Udry; Jean-Loup Bertaux; Jean-Pierre Sivan

2006-01-01

211

Low-Mass Inflation Systems for Inflatable Structures  

NASA Technical Reports Server (NTRS)

The use of inflatable space structures has often been proposed for aerospace and planetary applications. Communication, power generation, and very-long-baseline interferometry are just three potential applications of inflatable technology. The success of inflatable structures depends on the development of an applications of inflatable technology. This paper describes two design studies performed to develop a low mass inflation system. The first study takes advantage of existing onboard propulsion gases to reduce the overall system mass. The second study assumes that there is no onboard propulsion system. Both studies employ advanced components developed for the Pluto fast flyby spacecraft to further reduce mass. The study examined four different types of systems: hydrazine, nitrogen and water, nitrogen, and xenon. This study shows that all of these systems can be built for a small space structure with masses lower than 0.5 kilograms.

Thunnissen, Daniel P.; Webster, Mark S.; Engelbrecht, Carl S.

1995-01-01

212

Balloon borne optical disk mass storage system  

NASA Technical Reports Server (NTRS)

An on-board data recording system for balloon-borne interferometer using a vacuum operable, ruggedized WORM optical drive is presented. This system, as presently under development, provides 320 Mbytes of data storage (or approximately 11 hrs at the 64 kbits/sec telemetry rate of the experiment). It has the capability of recording the unmodified telemetry bit system as transmitted or doing some preprocessing of the data onboard. The system is compact and requires less than 28 watts of battery power to operate.

Vanek, M. D.; Jennings, D. A.

1991-01-01

213

Compressive mass analysis on quadrupole ion trap systems.  

PubMed

Conventionally, quadrupole ion trap mass spectrometers eject ions of different mass-to-charge ratio (m/z) in a sequential fashion by performing a scan of the rf trapping voltage amplitude. Due to the inherent sparsity of most mass spectra, the detector measures no signal for much of the scan time. By exploiting this sparsity property, we propose a new compressive and multiplexed mass analysis approach--multi Resonant Frequency Excitation (mRFE) ejection. This new approach divides the mass spectrum into several mass subranges and detects all the subrange spectra in parallel for increased mass analysis speed. Mathematical estimation of standard mass spectrum is demonstrated while statistical classification on the parallel measurements remains viable because of the sparse nature of the mass spectra. This method can reduce mass analysis time by a factor of 3-6 and increase system duty cycle by 2×. The combination of reduced analysis time and accurate compound classification is demonstrated in a commercial quadrupole ion trap (QIT) system. PMID:24806048

Chen, Evan Xuguang; Gehm, Michael; Danell, Ryan; Wells, Mitch; Glass, Jeffrey T; Brady, David

2014-07-01

214

Using GRACE measurements of time variable gravity, elevation changes from ICESat, OIB and ENVISAT and surface mass balance outputs from RACMO to improve ice mass balance estimates  

NASA Astrophysics Data System (ADS)

The glacial isostatic adjustment (GIA) correction represents a source of uncertainty for ice sheet mass balance estimates from the Gravity Recovery and Climate Experiment (GRACE) time variable gravity measurements. We evaluate Greenland and Antarctic GIA corrections by comparing the spatial patterns of GRACE-derived ice mass trends corrected for glacial isostatic adjustment with volume changes from ICESat (Ice, Cloud, and Land Elevation Satellite), OIB (Operation IceBridge) and ENVISAT altimetry missions, and surface mass balance (SMB) products from the Regional Atmospheric Climate Model (RACMO). We show that using the spatial and temporal characteristics of the different contributions to the ice mass balance estimates that it is possible to evaluate different GIA corrections. In Greenland, the GRACE ice mass changes obtained using the Simpson et al. (2009) and Geruo et al. (2013) GIA corrections show good agreement in the spatial patterns and amplitude. The GRACE estimate corrected using the Wu et al. (2010) GIA shows similar spatial patterns to the other two, but produces an average ice mass loss for the entire ice sheet that is 50% smaller. In Antarctica, the total magnitude and spatial structure of the GRACE-estimated ice mass change is highly dependent on the GIA correction. In key basins of East Antarctica, the interpretation of regional ice mass changes can reflect the GIA model selection as the ice mass to GIA signal ratio is smaller. We apply the same methodology used for the Greenland ice sheet in Antarctica to evaluate the different GIA corrections and check for consistency between the different techniques at a regional scale.

Sutterley, T. C.; Velicogna, I.; Csatho, B. M.; van den Broeke, M. R.; Wahr, J. M.; Flament, T.; Rezvan-Behbahani, S.; Babonis, G. S.; A, G.

2013-12-01

215

Satellite-based global-ocean mass balance estimates of interannual variability and emerging trends in continental freshwater discharge.  

PubMed

Freshwater discharge from the continents is a key component of Earth's water cycle that sustains human life and ecosystem health. Surprisingly, owing to a number of socioeconomic and political obstacles, a comprehensive global river discharge observing system does not yet exist. Here we use 13 years (1994-2006) of satellite precipitation, evaporation, and sea level data in an ocean mass balance to estimate freshwater discharge into the global ocean. Results indicate that global freshwater discharge averaged 36,055 km(3)/y for the study period while exhibiting significant interannual variability driven primarily by El Niño Southern Oscillation cycles. The method described here can ultimately be used to estimate long-term global discharge trends as the records of sea level rise and ocean temperature lengthen. For the relatively short 13-year period studied here, global discharge increased by 540 km(3)/y(2), which was largely attributed to an increase of global-ocean evaporation (768 km(3)/y(2)). Sustained growth of these flux rates into long-term trends would provide evidence for increasing intensity of the hydrologic cycle. PMID:20921364

Syed, Tajdarul H; Famiglietti, James S; Chambers, Don P; Willis, Josh K; Hilburn, Kyle

2010-10-19

216

Satellite-based global-ocean mass balance estimates of interannual variability and emerging trends in continental freshwater discharge  

PubMed Central

Freshwater discharge from the continents is a key component of Earth’s water cycle that sustains human life and ecosystem health. Surprisingly, owing to a number of socioeconomic and political obstacles, a comprehensive global river discharge observing system does not yet exist. Here we use 13 years (1994–2006) of satellite precipitation, evaporation, and sea level data in an ocean mass balance to estimate freshwater discharge into the global ocean. Results indicate that global freshwater discharge averaged 36,055 km3/y for the study period while exhibiting significant interannual variability driven primarily by El Niño Southern Oscillation cycles. The method described here can ultimately be used to estimate long-term global discharge trends as the records of sea level rise and ocean temperature lengthen. For the relatively short 13-year period studied here, global discharge increased by 540 km3/y2, which was largely attributed to an increase of global-ocean evaporation (768 km3/y2). Sustained growth of these flux rates into long-term trends would provide evidence for increasing intensity of the hydrologic cycle. PMID:20921364

Syed, Tajdarul H.; Famiglietti, James S.; Chambers, Don P.; Willis, Josh K.; Hilburn, Kyle

2010-01-01

217

Evaluation of probabilistic prediction systems for a scalar variable  

NASA Astrophysics Data System (ADS)

A systematic study is performed of a number of scores that can be used for objective validation of probabilistic prediction of scalar variables: Rank Histograms, Discrete and Continuous Ranked Probability Scores (DRPS and CRPS, respectively). The reliability-resolution-uncertainty decomposition, defined by Murphy for the DRPS, and extended here to the CRPS, is studied in detail. The decomposition is applied to the results of the Ensemble Prediction Systems of the European Centre for Medium-range Weather Forecasts and the National Centers for Environmental Prediction. Comparison is made with the decomposition of the CRPS defined by Hersbach. The possibility of determining an accurate reliability-resolution decomposition of the RPSs is severely limited by the unavoidably (relatively) small number of available realizations of the prediction system. The Hersbach decomposition may be an appropriate compromise between the competing needs for accuracy and practical computability.

Candille, G.; Talagrand, O.

2005-07-01

218

Concepts for Variable/Multi-Speed Rotorcraft Drive System  

NASA Technical Reports Server (NTRS)

In several recent studies and on-going developments for advanced rotorcraft, the need for variable or multi-speed capable rotors has been raised. A speed change of up to 50 percent has been proposed for future rotorcraft to improve overall vehicle performance. Accomplishing rotor speed changes during operation requires both a rotor that can perform effectively over the operation speed/load range, and a propulsion system that can enable these speed changes. A study has been completed to investigate possible drive system arrangements that can accommodate up to the 50 percent speed change. Several concepts will be presented and evaluated. The most promising configurations will be identified and developed for future testing in a sub-scaled test facility to validate operational capability.

Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

2008-01-01

219

Multiple reaction mass and isolation system  

NASA Technical Reports Server (NTRS)

System allows measurement of damping and stiffness with the desired uncoupling of measurement fixture and permits testing of large structures without need for costly foundation or base. System is designed to permit horizontal loading to be conveniently superimposed on vibratory loads.

Jacobson, N. F.

1972-01-01

220

Key Metrics System for Variety Steering in Mass Customization  

Microsoft Academic Search

The main goal of this paper is to provide a key metrics system for variety steering in mass customization. We distinguish between objective and subjective customer needs. The subjective needs are the individually realized and articulated requirements, whereas the objective needs are the real ones perceived by a fictive neutral perspective. We show that variety in mass customization has to

Thorsten Blecker; Nizar Abdelkafi; Bernd Kaluza; Gerhard Friedrich

2003-01-01

221

GROUNDWATER MASS TRANSPORT AND EQUILIBRIUM CHEMISTRY MODEL FOR MULTICOMPONENT SYSTEMS  

EPA Science Inventory

A mass transport model, TRANQL, for a multicomponent solution system has been developed. The equilibrium interaction chemistry is posed independently of the mass transport equations which leads to a set of algebraic equations for the chemistry coupled to a set of differential equ...

222

NASA Langley Research Center's distributed mass storage system  

NASA Technical Reports Server (NTRS)

There is a trend in institutions with high performance computing and data management requirements to explore mass storage systems with peripherals directly attached to a high speed network. The Distributed Mass Storage System (DMSS) Project at NASA LaRC is building such a system and expects to put it into production use by the end of 1993. This paper presents the design of the DMSS, some experiences in its development and use, and a performance analysis of its capabilities. The special features of this system are: (1) workstation class file servers running UniTree software; (2) third party I/O; (3) HIPPI network; (4) HIPPI/IPI3 disk array systems; (5) Storage Technology Corporation (STK) ACS 4400 automatic cartridge system; (6) CRAY Research Incorporated (CRI) CRAY Y-MP and CRAY-2 clients; (7) file server redundancy provision; and (8) a transition mechanism from the existent mass storage system to the DMSS.

Pao, Juliet Z.; Humes, D. Creig

1993-01-01

223

Canonical form observer design for non-linear time-variable systems  

Microsoft Academic Search

An observer of canonical (phase-variable) form for non-linear time-variable systems is introduced. The development of this non-linear time-variable form requires regularity of the non-linear time-variable- observability matrix of the system. From the relationships derived during the development, it follows that a non-linear time-variable observer can be dimensioned by an eigenvalue assignment with respect to the canonical state coordinates if a

D. BESTLE; M. ZEITZ

1983-01-01

224

Implications of Uncertainty and Variability in the Life Cycle Assessment of Pig Farming Systems  

Microsoft Academic Search

In a case study of pig production systems we propose a simple quantification of the uncertainty of LCA results (intra-system variability) and we ex plored inter-system variability in order to produce more robust LCA outcomes. Our quantification of the uncertainty took into account the variability of techni cal performance (crop yield, feed efficiency) and of em ission factors (for NH

C. Basset-Mens; P. Durand

225

A New Source Model of Non-Tidal Mass Variability in Atmosphere, Oceans, Terrestrial Hydrosphere, and the Solid Earth for Simulation Studies of Future Satellite Gravity Missions  

NASA Astrophysics Data System (ADS)

The ability of any satellite gravity mission concept to monitor mass transport processes in the Earth system is typically tested well ahead of its implementation by means of various simulation studies. Those studies often extend from the simulation of realistic orbits and instrumental data all the way down to the retrieval of global gravity field solution time-series. Basic requirement for all these simulations are realistic representations of the spatio-temporal mass variability in the different sub-systems of the Earth, as a source model for the orbit computations and assess the performance of the gravity field retrieval. For such simulations, a suitable source model is required to represent (i) high-frequency (~ daily) redistribution, for example, in the atmosphere and oceans, in order to realistically include the effects of temporal aliasing due to non-tidal high-frequency mass variability into the retrieved gravity fields. In parallel, (ii) low-frequency (weekly to monthly) variability needs to be modelled with realistic amplitudes, particularly at small spatial scales, in order to assess to what extent a new mission concept might provide further insight into physical processes currently not observable. The new source model presented in this study attempts to fulfil both requirements: Based on ECMWF's recent atmospheric reanalysis ERA Interim and corresponding simulations from numerical models of the other Earth system components, it offers spherical harmonic (SH) coefficients of the mass variability in atmosphere, oceans, the terrestrial hydrosphere including the ice-sheets and glaciers,as well as the solid Earth. Simulated features range from high temporal (6 hours) to long-term (inter-annual) with a spatial resolution of SH degree and order 180, encompassing a a period of 12 years. Associated with the source model, a de-aliasing model for atmospheric and oceanic high-frequency variability is available with augmented errors for a more realistic description of the process of the gravity field retrieval. Several features of this new dataset will be highlighted in this presentation in order to provide guidance for its application in upcoming future mission simulation studies.

Dobslaw, Henryk; Bergmann-Wolf, Inga; Dill, Robert; Klemann, Volker; Kusche, Jürgen; Sasgen, Ingo; Thomas, Maik

2014-05-01

226

Optimization of numerical parameters and solution procedures for a mass wall glazing system  

SciTech Connect

A study of various solution algorithms of a south facing vertical mass wall glazing system is presented. The optimization is completed in two parts. The variables chosen for the first part of the optimization include solution procedures, time steps, and grid spacings, used to model the mass wall. The four solution procedures used include an implicit scheme, an Euler scheme, an improved Euler scheme, and a Runge-Kutta solution scheme. This section was completed on a simulation of an unvented mass wall system and defines an optimal solution algorithm based on computer time and a one percent error limit on accuracy. This optimal solution algorithm is then applied to the vented mass wall system (Trombe wall). A further reduction in computer time could be achieved by utilizing equivalent conductances in the mass wall thermal network, provided there is no effect in the solution accuracy. The second part of the optimization examines the use of equivalent conductances in both the vented and unvented mass wall system.

White, M.D.; Burns, P.J.; Winn, C.B.

1980-01-01

227

Model-Based Systems Engineering Approach to Managing Mass Margin  

NASA Technical Reports Server (NTRS)

When designing a flight system from concept through implementation, one of the fundamental systems engineering tasks ismanaging the mass margin and a mass equipment list (MEL) of the flight system. While generating a MEL and computing a mass margin is conceptually a trivial task, maintaining consistent and correct MELs and mass margins can be challenging due to the current practices of maintaining duplicate information in various forms, such as diagrams and tables, and in various media, such as files and emails. We have overcome this challenge through a model-based systems engineering (MBSE) approach within which we allow only a single-source-of-truth. In this paper we describe the modeling patternsused to capture the single-source-of-truth and the views that have been developed for the Europa Habitability Mission (EHM) project, a mission concept study, at the Jet Propulsion Laboratory (JPL).

Chung, Seung H.; Bayer, Todd J.; Cole, Bjorn; Cooke, Brian; Dekens, Frank; Delp, Christopher; Lam, Doris

2012-01-01

228

Mesoscale and severe storms (Mass) data management and analysis system  

NASA Technical Reports Server (NTRS)

Progress on the Mesoscale and Severe Storms (MASS) data management and analysis system is described. An interactive atmospheric data base management software package to convert four types of data (Sounding, Single Level, Grid, Image) into standard random access formats is implemented and integrated with the MASS AVE80 Series general purpose plotting and graphics display data analysis software package. An interactive analysis and display graphics software package (AVE80) to analyze large volumes of conventional and satellite derived meteorological data is enhanced to provide imaging/color graphics display utilizing color video hardware integrated into the MASS computer system. Local and remote smart-terminal capability is provided by installing APPLE III computer systems within individual scientist offices and integrated with the MASS system, thus providing color video display, graphics, and characters display of the four data types.

Hickey, J. S.; Karitani, S.; Dickerson, M.

1984-01-01

229

Mass storage system reference model, Version 4  

NASA Technical Reports Server (NTRS)

The high-level abstractions that underlie modern storage systems are identified. The information to generate the model was collected from major practitioners who have built and operated large storage facilities, and represents a distillation of the wisdom they have acquired over the years. The model provides a common terminology and set of concepts to allow existing systems to be examined and new systems to be discussed and built. It is intended that the model and the interfaces identified from it will allow and encourage vendors to develop mutually-compatible storage components that can be combined to form integrated storage systems and services. The reference model presents an abstract view of the concepts and organization of storage systems. From this abstraction will come the identification of the interfaces and modules that will be used in IEEE storage system standards. The model is not yet suitable as a standard; it does not contain implementation decisions, such as how abstract objects should be broken up into software modules or how software modules should be mapped to hosts; it does not give policy specifications, such as when files should be migrated; does not describe how the abstract objects should be used or connected; and does not refer to specific hardware components. In particular, it does not fully specify the interfaces.

Coleman, Sam (editor); Miller, Steve (editor)

1993-01-01

230

A Conversational Mass Spectral Search System. IV. The Evolution of a System for the Retrieval of Mass Spectral Information  

ERIC Educational Resources Information Center

A prototype of an interactive, conversational mass spectral search system, developed at the National Institutes of Health, has been tested since September 1971 and is now being used by more than 200 scientists in the U.S. and Canada, and will soon be used by the international mass spectrometry community. (17 references) (SJ)

Heller, Stephen R.; And Others

1973-01-01

231

High-frequency X-ray variability as a mass estimator of stellar and supermassive black holes  

Microsoft Academic Search

There is increasing evidence that supermassive black holes in active galactic nuclei (AGN) are scaled-up versions of Galactic black holes. We show that the amplitude of high- frequency X-ray variability in the hard spectral state is in versely proportional to the black hole mass over eight orders of magnitude. We have analyzed all available hard-state data from RXTE of seven

Marek Gierli ´; Marek Nikoajuk

232

High-frequency X-ray variability as a mass estimator of stellar and supermassive black holes  

Microsoft Academic Search

There is increasing evidence that supermassive black holes in active galactic nuclei (AGN) are scaled-up versions of Galactic black holes. We show that the amplitude of high-frequency X-ray variability in the hard spectral state is inversely proportional to the black hole mass over eight orders of magnitude. We have analysed all available hard-state data from RXTE of seven Galactic black

Marek Gierlinski; Marek Nikolajuk; Bozena Czerny

2008-01-01

233

Small system for tritium accelerator mass spectrometry  

DOEpatents

Apparatus for ionizing and accelerating a sample containing isotopes of hydrogen and detecting the ratios of hydrogen isotopes contained in the sample is disclosed. An ion source generates a substantially linear ion beam including ions of tritium from the sample. A radio-frequency quadrupole accelerator is directly coupled to and axially aligned with the source at an angle of substantially zero degrees. The accelerator accelerates species of the sample having different mass to different energy levels along the same axis as the ion beam. A spectrometer is used to detect the concentration of tritium ions in the sample. In one form of the invention, an energy loss spectrometer is used which includes a foil to block the passage of hydrogen, deuterium and .sup.3 He ions, and a surface barrier or scintillation detector to detect the concentration of tritium ions. In another form of the invention, a combined momentum/energy loss spectrometer is used which includes a magnet to separate the ion beams, with Faraday cups to measure the hydrogen and deuterium and a surface barrier or scintillation detector for the tritium ions.

Roberts, Mark L. (Livermore, CA); Davis, Jay C. (Livermore, CA)

1993-01-01

234

Small system for tritium accelerator mass spectrometry  

DOEpatents

Apparatus for ionizing and accelerating a sample containing isotopes of hydrogen and detecting the ratios of hydrogen isotopes contained in the sample is disclosed. An ion source generates a substantially linear ion beam including ions of tritium from the sample. A radio-frequency quadrupole accelerator is directly coupled to and axially aligned with the source at an angle of substantially zero degrees. The accelerator accelerates species of the sample having different mass to different energy levels along the same axis as the ion beam. A spectrometer is used to detect the concentration of tritium ions in the sample. In one form of the invention, an energy loss spectrometer is used which includes a foil to block the passage of hydrogen, deuterium and [sup 3]He ions, and a surface barrier or scintillation detector to detect the concentration of tritium ions. In another form of the invention, a combined momentum/energy loss spectrometer is used which includes a magnet to separate the ion beams, with Faraday cups to measure the hydrogen and deuterium and a surface barrier or scintillation detector for the tritium ions.

Roberts, M.L.; Davis, J.C.

1993-02-23

235

Galactic model parameters of cataclysmic variables: Results from a new absolute magnitude calibration with 2MASS and WISE  

NASA Astrophysics Data System (ADS)

In order to determine the spatial distribution, Galactic model parameters and luminosity function of cataclysmic variables (CVs), a J-band magnitude limited sample of 263 CVs has been established using a newly constructed period-luminosity-colours (PLCs) relation which includes J,Ks and W1-band magnitudes in 2MASS and WISE photometries, and the orbital periods of the systems. This CV sample is assumed to be homogeneous regarding to distances as the new PLCs relation is calibrated with new or re-measured trigonometric parallaxes. Our analysis shows that the scaleheight of CVs is increasing towards shorter periods, although selection effects for the periods shorter than 2.25 h dramatically decrease the scaleheight: the scaleheight of the systems increases from 192 pc to 326 pc as the orbital period decreases from 12 to 2.25 h. The z-distribution of all CVs in the sample is well fitted by an exponential function with a scaleheight of 213-10+11 pc. However, we suggest that the scaleheight of CVs in the Solar vicinity should be ?300 pc and that the scaleheights derived using the sech2 function should be also considered in the population synthesis models. The space density of CVs in the Solar vicinity is found 5.58(1.35)×10-6 pc-3 which is in the range of previously derived space densities and not in agreement with the predictions of the population models. The analysis based on the comparisons of the luminosity function of white dwarfs with the luminosity function of CVs in this study show that the best fits are obtained by dividing the luminosity functions of white dwarfs by a factor of 350-450.

Özdönmez, A.; Ak, T.; Bilir, S.

2015-01-01

236

Variable Doppler shifts of the thermal wind absorption lines in low-mass X-ray binaries  

NASA Astrophysics Data System (ADS)

In this paper, we address the general applicability of the method pioneered by Zhang, Liao & Yao in which the motion of the compact object can be tracked using wind X-ray absorption lines. We present the velocity measurements of the thermal wind lines observed in the X-ray spectrum of a few low-mass X-ray binaries: GX 13+1, H 1743-322, GRO J1655-40 and GRS 1915+105. We find that the variability in the velocity of the wind lines in about all of the sources is larger than conceivable radial velocity variations of the compact object. GX 13+1 provides a potential exception, although it would require the red giant star to be massive with a mass of ?5-6 M?. We conclude that the variability of the source luminosity occurring on a time-scale of days/months can affect the outflow properties making it difficult to track the orbital motion of the compact object using current observations. Given the intrinsic variability of the outflows we suggest that low-mass X-ray binaries showing stable coronae instead of an outflow (e.g. 4U 1254-69, MXB 1659-29, 4U 1624-49) could be more suitable targets for tracking the orbital motion of the compact object.

Madej, O. K.; Jonker, P. G.; Díaz Trigo, M.; Miškovi?ová, I.

2014-02-01

237

Aerosol mass spectrometry systems and methods  

DOEpatents

A system according to one embodiment includes a particle accelerator that directs a succession of polydisperse aerosol particles along a predetermined particle path; multiple tracking lasers for generating beams of light across the particle path; an optical detector positioned adjacent the particle path for detecting impingement of the beams of light on individual particles; a desorption laser for generating a beam of desorbing light across the particle path about coaxial with a beam of light produced by one of the tracking lasers; and a controller, responsive to detection of a signal produced by the optical detector, that controls the desorption laser to generate the beam of desorbing light. Additional systems and methods are also disclosed.

Fergenson, David P.; Gard, Eric E.

2013-08-20

238

Accurate stellar masses in the multiple system T Tau  

E-print Network

The goal of this study is to obtain accurate estimates for the individual masses of the components of the tight binary system T Tau S in order to settle the ongoing debate on the nature of T Tau Sa, a so-called infrared companion. We take advantage of the fact that T Tau S belongs to a triple system composed of two hierarchical orbits to simultaneously analyze the motion of T Tau Sb in the rest frames of T Tau Sa and T Tau N. With this method, it is possible to pinpoint the location of the center of mass of T Tau S and, thereby, to determine individual masses for T Tau Sa and T Tau Sb with no prior assumption about the mass/flux ratio of the system. This improvement over previous studies of the system results in much better constraints on orbital parameters. We find individual masses of 2.73+/-0.31 Msun for T Tau Sa and of 0.61+/-0.17 Msun for T Tau Sb (in agreement with its early-M spectral type), including the uncertainty on the distance to the system. These are among the most precise estimates of the mass of any Pre-Main Sequence star, a remarkable result since this is the first system in which individual masses of T Tauri stars can be determined from astrometry only. This model-independent analysis confirms that T Tau Sa is an intermediate-mass star, presumably a very young Herbig Ae star, that may possess an almost edge-on disk.

G. Duchene; H. Beust; F. Adjali; Q. M. Konopacky; A. M. Ghez

2006-08-01

239

Electromagnetic variable degrees of freedom actuator systems and methods  

DOEpatents

The present invention provides a variable reluctance actuator system and method that can be adapted for simultaneous rotation and translation of a moving element by applying a normal-direction magnetic flux on the moving element. In a beneficial example arrangement, the moving element includes a swing arm that carries a cutting tool at a set radius from an axis of rotation so as to produce a rotary fast tool servo that provides a tool motion in a direction substantially parallel to the surface-normal of a workpiece at the point of contact between the cutting tool and workpiece. An actuator rotates a swing arm such that a cutting tool moves toward and away from a mounted rotating workpiece in a controlled manner in order to machine the workpiece. Position sensors provide rotation and displacement information for a swing arm to a control system. A control system commands and coordinates motion of the fast tool servo with the motion of a spindle, rotating table, cross-feed slide, and in feed slide of a precision lathe.

Montesanti, Richard C. (Pleasanton, CA); Trumper, David L. (Plaistow, NH); Kirtley, Jr., James L. (Brookline, MA)

2009-02-17

240

IMPACT OF PROCESS VARIABILITY ON LEAN MANUFACTURING SYSTEMS  

Microsoft Academic Search

This paper presents the impact of process variability on production and station\\/operator utilization in a manufacturing plant. Process variability is evaluated in terms of cycle time variance, Kanban capacities between manufacturing stations and mean cycle times. A simulation model was written in ProcessModel of the manufacturing line that was used to analyze process variability.

Mel Adams; Bernard J. Schroer; Larry R. Gunter; Bradley J. Schroer

241

Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources  

SciTech Connect

A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator – on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapor leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.

Hays, Lance G

2014-07-07

242

NCDC mass storage systems and technologies  

NASA Technical Reports Server (NTRS)

National Climatic Data Center (NCDC) data management issues are discussed, such as nature of holdings, history of the site, popularity of data sets, media/technology used for storage, volume distributed per month, mode of distribution, most frequently encountered problems, type of media requested/used, and evolution of media. Current holdings at NCDC are 107.8 terabytes of digital data and about 0.3 terabytes of manuscript data. The nexrad radar system is expected to generate approximately 88 terabytes per year by 1996.

Davis, Dick

1993-01-01

243

Comparison of Equivalent System Mass of Yeast and Flat Bread Systems  

Microsoft Academic Search

The Equivalent System Mass (ESM) metric developed by NASA describes and compares individual system impact on a closed system in terms of a single parameter, mass. The food system of a Mars mission may encompass a large percentage of total mission ESM, and decreasing this ESM would be beneficial. Yeast breads were made using three methods (hand & oven, bread

Ilan Weiss; Banu F. Ozen; Michele H. Perchonok; Kirby D. Hayes; Lisa J. Mauer

2003-01-01

244

Building and managing high performance, scalable, commodity mass storage systems  

NASA Technical Reports Server (NTRS)

The NAS Systems Division has recently embarked on a significant new way of handling the mass storage problem. One of the basic goals of this new development are to build systems at very large capacity and high performance, yet have the advantages of commodity products. The central design philosophy is to build storage systems the way the Internet was built. Competitive, survivable, expandable, and wide open. The thrust of this paper is to describe the motivation for this effort, what we mean by commodity mass storage, what the implications are for a facility that performs such an action, and where we think it will lead.

Lekashman, John

1998-01-01

245

Classes of bidimensional isospectral position-dependent mass systems  

E-print Network

In this work we construct a general class of exactly solvable non-relativistic bi-dimensional quantum systems with position-dependent masses (PDM). These systems are isospectral to a given system with constant mass. The case of a charged particle with a PDM interacting with an external magnetic field is included in the present investigation. We apply the approach in order to construct the SU(2) coherent states in some examples which are isospectral to the two-dimensional anisotropic harmonic oscillator, and discuss the impact of the introduction of special non-homogeneous external magnetic fields.

A. de Souza Dutra; J. A. de Oliveira

2010-02-24

246

Goddard Conference on Mass Storage Systems and Technologies, volume 2  

NASA Technical Reports Server (NTRS)

Papers and viewgraphs from the conference are presented. Discussion topics include the IEEE Mass Storage System Reference Model, data archiving standards, high-performance storage devices, magnetic and magneto-optic storage systems, magnetic and optical recording technologies, high-performance helical scan recording systems, and low end helical scan tape drives. Additional discussion topics addressed the evolution of the identifiable unit for processing (file, granule, data set, or some similar object) as data ingestion rates increase dramatically, and the present state of the art in mass storage technology.

Kobler, Ben (editor); Hariharan, P. C. (editor)

1993-01-01

247

Goddard Conference on Mass Storage Systems and Technologies, Volume 1  

NASA Technical Reports Server (NTRS)

Copies of nearly all of the technical papers and viewgraphs presented at the Goddard Conference on Mass Storage Systems and Technologies held in Sep. 1992 are included. The conference served as an informational exchange forum for topics primarily relating to the ingestion and management of massive amounts of data and the attendant problems (data ingestion rates now approach the order of terabytes per day). Discussion topics include the IEEE Mass Storage System Reference Model, data archiving standards, high-performance storage devices, magnetic and magneto-optic storage systems, magnetic and optical recording technologies, high-performance helical scan recording systems, and low end helical scan tape drives. Additional topics addressed the evolution of the identifiable unit for processing purposes as data ingestion rates increase dramatically, and the present state of the art in mass storage technology.

Kobler, Ben (editor); Hariharan, P. C. (editor)

1993-01-01

248

Design and Manufacturing of Extremely Low Mass Flight Systems  

NASA Technical Reports Server (NTRS)

Extremely small flight systems pose some unusual design and manufacturing challenges. The small size of the components that make up the system generally must be built with extremely tight tolerances to maintain the functionality of the assembled item. Additionally, the total mass of the system is extremely sensitive to what would be considered small perturbations in a larger flight system. The MUSES C mission, designed, built, and operated by Japan, has a small rover provided by NASA that falls into this small flight system category. This NASA-provided rover is used as a case study of an extremely small flight system design. The issues that were encountered with the rover portion of the MUSES C program are discussed and conclusions about the recommended mass margins at different stages of a small flight system project are presented.

Johnson, Michael R.

2002-01-01

249

Generalized framework for robust design of tuned mass damper systems  

Microsoft Academic Search

The primary purpose of this contribution is to develop a novel framework for generalized robust design of tuned mass damper (TMD) systems as passive vibration controllers for uncertain structures. This versatile strategy is intended to be free of any restriction on the structure–TMD system configuration, the performance criterion, and the number of uncertain parameters. The main idea pursued is to

Arash Mohtat; Ehsan Dehghan-Niri

2011-01-01

250

Specialized Gas Chromatography--Mass Spectrometry Systems for Clinical Chemistry.  

ERIC Educational Resources Information Center

A discussion of the basic design and characteristics of gas chromatography-mass spectrometry systems used in clinical chemistry. A comparison of three specific systems: the Vitek Olfax IIA, Hewlett-Packard HP5992, and Du Pont DP-102 are included. (BB)

Gochman, Nathan; And Others

1979-01-01

251

EVALUATION OF A SULFUR DIOXIDE MASS EMISSION RATE MONITORING SYSTEM  

EPA Science Inventory

An evaluation was conducted to determine the capabilities and limitations of a commercially available monitoring system that provides sulfur dioxide mass emission rate data as a direct output. The monitoring system was operated continuously for extended periods at a coal-fired po...

252

Sodium Variable Conductance Heat Pipe for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

In a Stirling radioisotope system, heat must continually be removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the converter stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, and also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) has been designed to allow multiple stops and restarts of the Stirling convertor in an Advanced Stirling Radioisotope Generator (ASRG). When the Stirling convertor is turned off, the VCHP will activate when the temperatures rises 30 C above the setpoint temperature. A prototype VCHP with sodium as the working fluid was fabricated and tested in both gravity aided and against gravity conditions for a nominal heater head temperature of 790 C. The results show very good agreement with the predictions and validate the model. The gas front was located at the exit of the reservoir when heater head temperature was 790 C while cooling was ON, simulating an operating Advanced Stirling Converter (ASC). When cooling stopped, the temperature increased by 30 C, allowing the gas front to move past the radiator, which transferred the heat to the case. After resuming the cooling flow, the front returned at the initial location turning OFF the VCHP. The against gravity working conditions showed a colder reservoir and faster transients.

Tarau, Calin; Anderson, William G.; Walker, Kara

2009-01-01

253

Entanglement, Purity, and Information Entropies in Continuous Variable Systems  

E-print Network

Quantum entanglement of pure states of a bipartite system is defined as the amount of local or marginal ({\\em i.e.}referring to the subsystems) entropy. For mixed states this identification vanishes, since the global loss of information about the state makes it impossible to distinguish between quantum and classical correlations. Here we show how the joint knowledge of the global and marginal degrees of information of a quantum state, quantified by the purities or in general by information entropies, provides an accurate characterization of its entanglement. In particular, for Gaussian states of continuous variable systems, we classify the entanglement of two--mode states according to their degree of total and partial mixedness, comparing the different roles played by the purity and the generalized $p-$entropies in quantifying the mixedness and bounding the entanglement. We prove the existence of strict upper and lower bounds on the entanglement and the existence of extremally (maximally and minimally) entangled states at fixed global and marginal degrees of information. This results allow for a powerful, operative method to measure mixed-state entanglement without the full tomographic reconstruction of the state. Finally, we briefly discuss the ongoing extension of our analysis to the quantification of multipartite entanglement in highly symmetric Gaussian states of arbitrary $1 \\times N$-mode partitions.

Gerardo Adesso; Alessio Serafini; Fabrizio Illuminati

2005-06-06

254

Variable-Tension-Cord Suspension/Vibration-Isolation System  

NASA Technical Reports Server (NTRS)

A system for mechanical suspension and vibration isolation of a machine or instrument is based on the use of Kevlar (or equivalent aromatic polyamide) cord held in variable tension between the machine or instrument and a surrounding frame. The basic concept of such a tensioned-cord suspension system (including one in which the cords are made of aromatic polyamide fibers) is not new by itself; what is new here is the additional provision for adjusting the tension during operation to optimize vibration- isolation properties. In the original application for which this system was conceived, the objective is to suspend a reciprocating cryocooler aboard a space shuttle and to prevent both (1) transmission of launch vibrations to the cryocooler and (2) transmission of vibrations from the cryocooler to samples in a chamber cooled by the cryocooler. The basic mechanical principle of this system can also be expected to be applicable to a variety of other systems in which there are requirements for cord suspension and vibration isolation. The reciprocating cryocooler of the original application is a generally axisymmetric object, and the surrounding frame is a generally axisymmetric object with windows (see figure). Two cords are threaded into a spoke-like pattern between attachment rings on the cryocooler, holes in the cage, and cord-tension- adjusting assemblies. Initially, the cord tensions are adjusted to at least the level necessary to suspend the cryocooler against gravitation. Accelerometers for measuring vibrations are mounted (1) on the cold tip of the cryocooler and (2) adjacent to the cage, on a structure that supports the cage. During operation, a technician observes the accelerometer outputs on an oscilloscope while manually adjusting the cord tensions in an effort to minimize the amount of vibration transmitted to and/or from the cryocooler. A contemplated future version of the system would include a microprocessor-based control subsystem that would include cord-tension actuators. This control subsystem would continually adjust the cord tension in response to accelerometer feedback to optimize vibration-isolation properties as required for various operating conditions. The control system could also adjust cord tensions (including setting the two cords to different tensions) to suppress resonances. Other future enhancements could include optimizing the cord material, thickness, and braid; optimizing the spoke patterns; and adding longitudinal cords for applications in which longitudinal stiffness and vibration suppression are required.

Villemarette, Mark L.; Boston, Joshua; RInks, Judith; Felice, Pat; Stein, Tim; Payne, Patrick

2006-01-01

255

Design of test-control system based on MCU for variable speed hydraulic system  

Microsoft Academic Search

Aiming at variable speed hydraulic compositive test stand, this paper designed the test-control system based on Microcontroller Unit (MCU), determined hardware composition of the test-control system and connection circuit of every part. The test-control system can acomplish multi-channel signal acquisition, keyboard input and realtime display of measured parameter. With the D\\/A output channel, it can realize open or closed loop

Tianhao Peng; Xiaosong Hao; Jiadong Liu; Meisheng Yang

2011-01-01

256

Satellite masses in the Uranus and Neptune systems  

SciTech Connect

Satellite masses are derivation with emphasis on implications for bulk densities and albedos is reviewed. In the Uranian system the inner satellites have lower densities and/or higher albedos than the outer ones. However, uncertainties are great enough that all five satellites may have nearly equal densities. In such a case the albedo would decrease with semimajor axis. A more severe constraint is placed on Miranda's mass, and hence on its density and albedo. The recent radiometric value for Triton's diameter, combined with mass determinations, yields a density greater than 4 gm/cm3.

Greenberg, R.

1984-10-01

257

Performance evaluation of mass storage systems for scientific databases  

SciTech Connect

Mass storage systems for computers are the solution to economic storage of vast volumes of data. These systems evolved from the traditional tape libraries manned by operating personnel and the automation of the storage and retrieval function has led to significant improvement in performance. But in contrast to traditional computer systems, little work has been done to characterize performance in terms of the design parameters. The design and performance analysis of mass storage systems is complicated due to several reasons. A major reason for the complexity is the time lags that may occur in retrieving parts of the information meant for the same query. The usual queuing models used for analyzing disk performance are not directly applicable, because there is greater scope for working in parallel in mass storage systems such as robotic libraries, which help mitigate these shortcomings. In this note, robotic libraries are modeled as queueing systems and explicit results related to performance are obtained. The physical model corresponds to a mass storage system, where the information is stored in cassettes, which are retrieved by robots to be read using one or two read heads. The results pertain to the effect of file splitting on cassettes, and optimal configuration and control of robots that perform the retrieval and storage functions.

Segev, A. [Univ. of California, Berkeley, CA (United States). Haas School of Business]|[Lawrence Berkeley Lab., CA (United States). Information and Computing Sciences Div.; Seshadri, S. [Univ. of California, Berkeley, CA (United States). Haas School of Business; Rotem, D. [Lawrence Berkeley Lab., CA (United States). Information and Computing Sciences Div.

1994-09-01

258

The FAST-AIMS Clinical Mass Spectrometry Analysis System  

PubMed Central

Within clinical proteomics, mass spectrometry analysis of biological samples is emerging as an important high-throughput technology, capable of producing powerful diagnostic and prognostic models and identifying important disease biomarkers. As interest in this area grows, and the number of such proteomics datasets continues to increase, the need has developed for efficient, comprehensive, reproducible methods of mass spectrometry data analysis by both experts and nonexperts. We have designed and implemented a stand-alone software system, FAST-AIMS, which seeks to meet this need through automation of data preprocessing, feature selection, classification model generation, and performance estimation. FAST-AIMS is an efficient and user-friendly stand-alone software for predictive analysis of mass spectrometry data. The present resource review paper will describe the features and use of the FAST-AIMS system. The system is freely available for download for noncommercial use. PMID:19956420

Fananapazir, Nafeh; Statnikov, Alexander; Aliferis, Constantin F.

2009-01-01

259

Targeted Multiplex Imaging Mass Spectrometry with Single Chain Fragment Variable (scfv) Recombinant Antibodies  

NASA Astrophysics Data System (ADS)

Recombinant scfv antibodies specific for CYP1A1 and CYP1B1 P450 enzymes were combined with targeted imaging mass spectrometry to simultaneously detect the P450 enzymes present in archived, paraffin-embedded, human breast cancer tissue sections. By using CYP1A1 and CYP1B1 specific scfv, each coupled to a unique reporter molecule (i.e., a mass tag) it was possible to simultaneously detect multiple antigens within a single tissue sample with high sensitivity and specificity using mass spectrometry. The capability of imaging multiple antigens at the same time is a significant advance that overcomes technical barriers encountered when using present day approaches to develop assays that can simultaneously detect more than a single antigen in the same tissue sample.

Thiery, Gwendoline; Mernaugh, Ray L.; Yan, Heping; Spraggins, Jeffrey M.; Yang, Junhai; Parl, Fritz F.; Caprioli, Richard M.

2012-10-01

260

39INTERPLAY OF MASS-TRANSPORT AND TURBIDITE-SYSTEM DEPOSITS Mass-Transport Deposits in Deepwater Settings  

E-print Network

39INTERPLAY OF MASS-TRANSPORT AND TURBIDITE-SYSTEM DEPOSITS Mass-Transport Deposits in Deepwater-1-56576-287-9, p. 39­66. INTERPLAY OF MASS-TRANSPORT AND TURBIDITE-SYSTEM DEPOSITS IN DIFFERENT ACTIVE TECTONIC AND PASSIVE CONTINENTAL MARGIN SETTINGS: EXTERNAL AND LOCAL CONTROLLING FACTORS C. HANS NELSON Instituto

Goldfinger, Chris

261

Entanglement in continuous variable systems: Recent advances and current perspectives  

E-print Network

We review the theory of continuous-variable entanglement with special emphasis on foundational aspects, conceptual structures, and mathematical methods. Much attention is devoted to the discussion of separability criteria and entanglement properties of Gaussian states, for their great practical relevance in applications to quantum optics and quantum information, as well as for the very clean framework that they allow for the study of the structure of nonlocal correlations. We give a self-contained introduction to phase-space and symplectic methods in the study of Gaussian states of infinite-dimensional bosonic systems. We review the most important results on the separability and distillability of Gaussian states and discuss the main properties of bipartite entanglement. These include the extremal entanglement, minimal and maximal, of two-mode mixed Gaussian states, the ordering of two-mode Gaussian states according to different measures of entanglement, the unitary (reversible) localization, and the scaling of bipartite entanglement in multimode Gaussian states. We then discuss recent advances in the understanding of entanglement sharing in multimode Gaussian states, including the proof of the monogamy inequality of distributed entanglement for all Gaussian states, and its consequences for the characterization of multipartite entanglement. We finally review recent advances and discuss possible perspectives on the qualification and quantification of entanglement in non Gaussian states, a field of research that is to a large extent yet to be explored.

Gerardo Adesso; Fabrizio Illuminati

2007-06-27

262

Fermilab's multi-petabyte scalable mass storage system  

SciTech Connect

Fermilab provides a multi-Petabyte scale mass storage system for High Energy Physics (HEP) Experiments and other scientific endeavors. We describe the scalability aspects of the hardware and software architecture that were designed into the Mass Storage System to permit us to scale to multiple petabytes of storage capacity, manage tens of terabytes per day in data transfers, support hundreds of users, and maintain data integrity. We discuss in detail how we scale the system over time to meet the ever-increasing needs of the scientific community, and relate our experiences with many of the technical and economic issues related to scaling the system. Since the 2003 MSST conference, the experiments at Fermilab have generated more than 1.9 PB of additional data. We present results on how this system has scaled and performed for the Fermilab CDF and D0 Run II experiments as well as other HEP experiments and scientific endeavors.

Oleynik, Gene; Alcorn, Bonnie; Baisley, Wayne; Bakken, Jon; Berg, David; Berman, Eileen; Huang, Chih-Hao; Jones, Terry; Kennedy, Robert D.; Kulyavtsev, Alexander; Moibenko, Alexander; Perelmutov, Timur; Petravick, Don; Podstavkov, Vladimir; Szmuksta, George; Zalokar, Michael; /Fermilab

2005-01-01

263

Ultrasensitive nanomechanical mass sensor using hybrid opto-electromechanical systems.  

PubMed

Nanomechanical resonators provide an unparalleled mass sensitivity sufficient to detect single biomolecules, viruses and nanoparticles. In this work we propose a scheme for mass sensing based on the hybrid opto-electromechanical system, where a mechanical resonator is coupled to an optical cavity and a microwave cavity simultaneously. When the two cavities are driven by two pump fields with proper frequencies and powers, a weak probe field is used to scan across the optical cavity resonance frequency. The mass of a single baculovirus landing onto the surface of the mechanical resonator can be measured by tracking the resonance frequency shift in the probe transmission spectrum before and after the deposition. We also propose a nonlinear mass sensor based on the measurement of the four-wave mixing (FWM) spectrum, which can be used to weigh a single 20-nm-diameter gold nanoparticle with sub-femtogram resolution. PMID:24921569

Jiang, Cheng; Cui, Yuanshun; Zhu, Ka-Di

2014-06-01

264

Dust composition and mass-loss return from the luminous blue variable R71 in the LMC  

NASA Astrophysics Data System (ADS)

Context. We present an analysis of mid- and far-infrared (IR) spectrum and spectral energy distribution (SED) of the luminous blue variable (LBV) R71 in the Large Magellanic Cloud (LMC). Aims: This work aims to understand the overall contribution of high-mass LBVs to the total dust-mass budget of the interstellar medium (ISM) of the LMC and compare this with the contribution from low-mass asymptotic giant branch (AGB) stars. As a case study, we analyze the SED of R71. Methods: We compiled all the available photometric and spectroscopic observational fluxes from various telescopes for a wide wavelength range (0.36-250 ?m). We determined the dust composition from the spectroscopic data, and derived the ejected dust mass, dust mass-loss rate, and other dust shell properties by modeling the SED of R71. We noted nine spectral features in the dust shell of R71 by analyzing Spitzer Space Telescope spectroscopic data. Among these, we identified three new crystalline silicate features. We computed our model spectrum by using 3D radiative transfer code MCMax. Results: Our model calculation shows that dust is dominated by amorphous silicates, with some crystalline silicates, metallic iron, and a very tiny amount of polycyclic aromatic hydrocarbon (PAH) molecules. The presence of both silicates and PAHs indicates that the dust has a mixed chemistry. We derived a dust mass of 0.01 M?, from which we arrive at a total ejected mass of ?5 M?. This implies a time-averaged dust mass-loss rate of 2.5 × 10-6 M? yr-1 with an explosion about 4000 years ago. We assume that the other five confirmed dusty LBVs in the LMC loose mass at a similar rate, and estimate the total contribution to the mass budget of the LMC to be ?10-5 M? yr-1, which is comparable to the contribution by all the AGB stars in the LMC. Conclusions: Based on our analysis on R71, we speculate that LBVs as a class may be an important dust source in the ISM of the LMC.

Guha Niyogi, S.; Min, M.; Meixner, M.; Waters, L. B. F. M.; Seale, J.; Tielens, A. G. G. M.

2014-09-01

265

Geomorphological characteristics and variability of Holocene mass-transport complexes, St. Lawrence River Estuary, Canada  

NASA Astrophysics Data System (ADS)

Recently acquired multibeam bathymetry data are used to investigate seafloor instability features along a 310 km-long segment of the St. Lawrence River Estuary. The analysis of this dataset indicates that submarine slides occur over a much larger area than previously recognized and that Holocene sediments are reworked by mass-transport along significant portions of both the northwest and southeast margins of the Laurentian Channel. In the surveyed area, 96 individual mass-transport complexes (MTCs) were identified representing 13% of the seabed. MTCs vary in area from less than 1 km2 to more than 40 km2 and exhibit various geomorphological signatures. Qualitative observation reveals an apparent disparity between MTCs that remain coherent and those that disintegrate during downslope transport evolving into a blocky morphological signature. For all MTCs, morphological parameters have been measured (area, length, and height) or calculated (slope and roughness). This quantitative analysis provides a unique opportunity to study these parameters in a statistically significant and homogeneous dataset located in a relatively small area that experienced a similar Quaternary history. In many cases, mass transport events appear to initiate in the vicinity of steep bedrock walls located along some segments of the estuary. The timing of mass-transport events was not constrained during this study. However, the fact that the region hosts the Charlevoix seismic zone, the most tectonically active area in eastern Canada, strongly suggests that earthquakes acted as a trigger for submarine landsliding.

Pinet, Nicolas; Brake, Virginia; Campbell, Calvin; Duchesne, Mathieu J.

2015-01-01

266

VARIABLE BOUND-SITE CHARGING CONTRIBUTIONS TO SURFACE COMPLEXATION MASS ACTION EXPRESSIONS  

EPA Science Inventory

One and two pK models of surface complexation reactions between reactive surface sites (>SOH) and the proton (H+) use mass action expressions of the form: Ka={[>SOHn-1z-1]g>SOH(0-1)aH+EXP(-xeY/kT)}/{[>SOHnz]g>SOH(n)} where Ka=the acidity constant, [ ]=reactive species concentrati...

267

CORONAL MASS EJECTIONS AS A MECHANISM FOR PRODUCING IR VARIABILITY IN DEBRIS DISKS  

SciTech Connect

Motivated by recent observations of short-timescale variations in the infrared emission of circumstellar disks, we propose that coronal mass ejections can remove dust grains on timescales as short as a few days. Continuous monitoring of stellar activity, coupled with infrared observations, can place meaningful constraints on the proposed mechanism.

Osten, Rachel; Livio, Mario; Lubow, Steve; Pringle, J. E.; Soderblom, David; Valenti, Jeff [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

2013-03-10

268

Design and research on a variable ballast system for deep-sea manned submersibles  

NASA Astrophysics Data System (ADS)

Variable ballast systems are necessary for manned submersibles to adjust their buoyancy. In this paper, the design of a variable ballast system for a manned submersible is described. The variable ballast system uses a super high pressure hydraulic seawater system. A super high pressure seawater pump and a deep-sea brushless DC motor are used to pump seawater into or from the variable ballast tank, increasing or decreasing the weight of the manned submersible. A magnetostrictive linear displacement transducer can detect the seawater level in the variable ballast tank. Some seawater valves are used to control pumping direction and control on-off states. The design and testing procedure for the valves is described. Finally, the future development of variable ballast systems and seawater hydraulic systems is projected.

Qiu, Zhong-Liang

2008-12-01

269

The pulsation modes and masses of carbon-rich long period variables  

Microsoft Academic Search

Following our study of the carbon-rich giants in the HR diagram and of their luminosity function (Paper III), we investigate the pulsation data of the long period variables (LPVs) included in our sample. Pulsation modes (fundamental, overtone(s)) for carbon LPVs are identified in the period-radius diagram, making use of observed bi-periodicity in a small subsample of those stars, and of

J. Bergeat; A. Knapik; B. Rutily

2002-01-01

270

Variability of the thermohaline structure in the northern Veracruz Coral Reef System, Mexico  

NASA Astrophysics Data System (ADS)

The variability of the thermohaline fields is studied at different time scales in the Veracruz Coral Reef System (VCRS) with hydrographic data from eleven CTD campaigns carried out from 2006 to 2010 and time series of temperature obtained from a mooring array (22 months) and from a current profiler (21 months). Results show that, from October to March, the vertical structure of temperature was quasi-homogeneous, with temperature differences between surface and bottom waters of less than 0.5 °C, and temperature inversions were frequently observed. By contrast, strong stratification was observed in late spring and summer when the surface—bottom temperature difference can be larger than 8 °C. In some years, the lower bottom temperatures were observed during summer. The lower temperatures of the 2007-2010 period were observed during winter 2010, being 2 °C to 4 °C lower than those observed in the previous years. It was also the year showing more temperature variability during the summer months due to several atmospheric tropical systems that affected the region, like tropical cyclone Alex. The dominant water mass at the VCRS observed during the study period was the Gulf Common Water, with salinities lower than 36.5 psu and temperatures between 21.2 °C and 30.0 °C. In addition, during summer, high temperature and low salinity water from local rivers was observed in the upper 6 m. During autumn-winter, low temperature and salinity waters coming from the northwestern shelves of the gulf were observed.

Mateos-Jasso, Adriana; Zavala-Hidalgo, Jorge; Romero-Centeno, Rosario; Allende-Arandía, María E.

2012-12-01

271

The Longterm Variability of 4u 1705-44---A Chaotic System?  

NASA Astrophysics Data System (ADS)

The bright low-mass X-ray binary 4U 1705-44, a bursting Atoll source, exhibits longterm aperiodic variability with a timescale of several hundred days. The All-Sky Monitor (ASM) aboard the Rossi X-ray Timing Explorer (RXTE) observed 4U 1705-44 continuously from December 1995 through January 2012. MAXI, the Japanese X-ray All-Sky Monitor aboard the International Space Station observed the source from August 2009 through the present. Combining the ASM and MAXI data sets yeilds a continuous, uninterrupted, evenly spaced time series containing over fifty cycles at the timescale of interest. We use traditional and novel time series analysis techniques to analyze the longterm variability. A phase space embedding of the flux versus its first derivative shows a strong resemblence to the canonical double-welled nonlinear Duffing osciallator. We find a range of parameters and initial conditions for which the Duffing oscillator closely follows the time evolution of 4U 1705-44. We find evidence for unstable periodic orbits embedded in the aperiodc variabiity of 4U 1705-44, and argue that the period-1 orbit has a period of ~120 days. Clear signatures of period-1, period-2 and period-3 orbits are found in the light curve. We extract these orbits from both the 4U 1705-44 and Duffing oscillator time series and compare their topological information in phase space. It appears that the X-ray long term time variability of 4U 1705-44 can be described by a Duffing oscillator. We discuss the implications of this discovery on the allowable models to describe the longterm variability of 4U 1705-44 and, by extention, to the allowable models describing the class of X-ray binaries which show high amplitude, longterm variabilty at timescales many times the orbital periods of the systems.

Boyd, Patricia T.; Nichols, Rebecca; Smale, Alan

2015-01-01

272

DETECTION OF LOW-MASS-RATIO STELLAR BINARY SYSTEMS  

SciTech Connect

O- and B-type stars are often found in binary systems, but the low binary mass-ratio regime is relatively unexplored due to observational difficulties. Binary systems with low mass ratios may have formed through fragmentation of the circumstellar disk rather than molecular cloud core fragmentation. We describe a new technique sensitive to G- and K-type companions to early B stars, a mass ratio of roughly 0.1, using high-resolution, high signal-to-noise spectra. We apply this technique to a sample of archived VLT/CRIRES observations of nearby B stars in the CO bandhead near 2300 nm. While there are no unambiguous binary detections in our sample, we identify HIP 92855 and HIP 26713 as binary candidates warranting follow-up observations. We use our non-detections to determine upper limits to the frequency of FGK stars orbiting early B-type primaries.

Gullikson, Kevin; Dodson-Robinson, Sarah [Astronomy Department, University of Texas, 1 University Station C1400, Austin, TX 78712 (United States)

2013-01-01

273

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems  

E-print Network

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems B. Beltran, T. Ahmed power generation in variable speed wind energy conversion systems (VS-WECS). These systems have two (National Renewable Energy Laboratory) wind turbine simulator FAST (Fatigue, Aerodynamics, Structures

Boyer, Edmond

274

Modeling and Managing the Variability of Web Service-based Systems  

E-print Network

Modeling and Managing the Variability of Web Service-based Systems Chang-ai Sun a,, Rowan Rossing b and manage variability would greatly facilitate the creation and customization of Web service-based systems systems that need to communicate and interoperate over the Internet or corporate intranets. Supermarkets

Aiello, Marco

275

Characteristics, processes, and causes of the spatio-temporal variabilities of the East Asian monsoon system  

NASA Astrophysics Data System (ADS)

Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon (EAM) system are reviewed in this paper. The understanding of the EAM system has improved in many aspects: the basic characteristics of horizontal and vertical structures, the annual cycle of the East Asian summer monsoon (EASM) system and the East Asian winter monsoon (EAWM) system, the characteristics of the spatio-temporal variabilities of the EASM system and the EAWM system, and especially the multiple modes of the EAM system and their spatio-temporal variabilities. Some new results have also been achieved in understanding the atmosphere-ocean interaction and atmosphere-land interaction processes that affect the variability of the EAM system. Based on recent studies, the EAM system can be seen as more than a circulation system, it can be viewed as an atmosphere-ocean-land coupled system, namely, the EAM climate system. In addition, further progress has been made in diagnosing the internal physical mechanisms of EAM climate system variability, especially regarding the characteristics and properties of the East Asia-Pacific (EAP) teleconnection over East Asia and the North Pacific, the "Silk Road" teleconnection along the westerly jet stream in the upper troposphere over the Asian continent, and the dynamical effects of quasi-stationary planetary wave activity on EAM system variability. At the end of the paper, some scientific problems regarding understanding the EAM system variability are proposed for further study.

Huang, Ronghui; Chen, Jilong; Wang, Lin; Lin, Zhongda

2012-09-01

276

A system of three-dimensional complex variables  

NASA Technical Reports Server (NTRS)

Some results of a new theory of multidimensional complex variables are reported, including analytic functions of a three-dimensional (3-D) complex variable. Three-dimensional complex numbers are defined, including vector properties and rules of multiplication. The necessary conditions for a function of a 3-D variable to be analytic are given and shown to be analogous to the 2-D Cauchy-Riemann equations. A simple example also demonstrates the analogy between the newly defined 3-D complex velocity and 3-D complex potential and the corresponding ordinary complex velocity and complex potential in two dimensions.

Martin, E. Dale

1986-01-01

277

Optical Monitoring and Period Analysis of High Mass X-Ray Binary System BD+53 2262  

NASA Astrophysics Data System (ADS)

High mass X-ray binary systems (HMXB) are usually composed of a B spectral type star and a neutron star. These systems have been primarily observed in the X-ray regime and as such their optical properties have not been thoroughly studied. We hypothesize that variability/periodicity in the optical brightness should be present and correlate with variability at other wavelengths. For the last five summers, optical observations of HMXB system BD+53 2262 have been gathered on the David Derrick 16’’ telescope located at Brigham Young University. To probe for long-term and short term variability, observations were taken in quick succession in one filter over the course of a night and also shorter observations through multiple filters spaced over many nights. The observations are primarily in the Johnson V filter, with B and I added in 2010, and R in 2011. We present optical light curves for five years of observations of the system BD+53 2262. There is a definite decrease in magnitude in the past five years and small monthly variations in three of the four years. These indicate a long term periodicity on the range of years and some shorter term periodicity in the range of months, consistent with what was expected. Period analysis has been done on the data and preliminary results will be presented. We will keep observing this system to see if there is further evidence of long term periodicity and to see if the monthly variations continue.

Zurita, Nathaly; Hintz, E. G.

2012-05-01

278

Dual Source Mass Spectrometer and Sample Handling System  

NASA Technical Reports Server (NTRS)

We present details of a miniature integrated time-of-flight mass spectrometer and sample handling system under development to address some of the needs for in situ sample analysis on landed missions. Additional information is contained in the original extended abstract.

Brinckerhoff, W. B.; Mahaffy, P. R.; Cornish, T. J.; Cheng, A. F.; Niemann, H. B.; Harpold, D. N.; Gorevan, S. P.; Rafeek, S.; Yucht, D.

2002-01-01

279

Advanced Life Support Equivalent System Mass Guidelines Document  

NASA Technical Reports Server (NTRS)

This document is a viewgraph presentation which provides guidelines for performing an Equivalent System Mass (ESM) evaluation for trade study purposes. The document: 1) Defines ESM; 2) Explains how to calculate ESM; 3) Discusses interpretation of ESM results. The document is designed to provide detailed instructive material for researchers who are performing ESM evaluations for the first time.

Levri, Julie; Fisher, John W.; Jones, Harry W.; Drysdale, Alan E.; Ewert, Michael K.; Hanford, Anthony J.; Hogan, John A.; Joshi, Jitendri, A.; Vaccari, David A.

2003-01-01

280

Mass memory decisions (for tomorrow's advanced aeronautical weapon systems)  

Microsoft Academic Search

It is pointed out that selecting a mass memory technology for tomorrow's aeronautical weapon systems depends on the environment, capacity, throughput, and cost. The author briefly overviews a 21st-century battlefield scenario, discusses the capacity, throughput (in terms of access speeds), and environmental requirements necessary to meet this scenario, explains how some technologies have evolved to meet these requirements, and briefly

Jeffrey F. Brown; Wright-Patterson AFB

1991-01-01

281

A common mass scaling for satellite systems of gaseous planets.  

PubMed

The Solar System's outer planets that contain hydrogen gas all host systems of multiple moons, which notably each contain a similar fraction of their respective planet's mass (approximately 10(-4)). This mass fraction is two to three orders of magnitude smaller than that of the largest satellites of the solid planets (such as the Earth's Moon), and its common value for gas planets has been puzzling. Here we model satellite growth and loss as a forming giant planet accumulates gas and rock-ice solids from solar orbit. We find that the mass fraction of its satellite system is regulated to approximately 10(-4) by a balance of two competing processes: the supply of inflowing material to the satellites, and satellite loss through orbital decay driven by the gas. We show that the overall properties of the satellite systems of Jupiter, Saturn and Uranus arise naturally, and suggest that similar processes could limit the largest moons of extrasolar Jupiter-mass planets to Moon-to-Mars size. PMID:16778883

Canup, Robin M; Ward, William R

2006-06-15

282

Estimation of convective mass transfer in solar distillation systems  

Microsoft Academic Search

In this article a thermal model has been developed to determine the convective mass transfer for different Grashof Number range in solar distillatiOn process. The model is based on simple regression analysis. Based on the experimental data obtained from the rigorous outdoor experimentation on passive and active distillation systems for summer climatic conditions, the values of C and n have

Sanjay Kumar; G. N. Tiwari

1996-01-01

283

An independent limit on the axion mass from the variable white dwarf star R548  

SciTech Connect

Pulsating white dwarfs with hydrogen-rich atmospheres, also known as DAV stars, can be used as astrophysical laboratories to constrain the properties of fundamental particles like axions. Comparing the measured cooling rates of these stars with the expected values from theoretical models allows us to search for sources of additional cooling due to the emission of weakly interacting particles. In this paper, we present an independent inference of the mass of the axion using the recent determination of the evolutionary cooling rate of R548, the DAV class prototype. We employ a state-of-the-art code which allows us to perform a detailed asteroseismological fit based on fully evolutionary sequences. Stellar cooling is the solely responsible of the rates of change of period with time (.?)) for the DAV class. Thus, the inclusion of axion emission in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DAV stars. This allows us to compare the theoretical .?) values to the corresponding empirical rate of change of period with time of R548 to discern the presence of axion cooling. We found that if the dominant period at 213.13 s in R548 is associated with a pulsation mode trapped in the hydrogen envelope, our models indicate the existence of additional cooling in this pulsating white dwarf, consistent with axions of mass m{sub a}cos {sup 2}? ? 17.1 meV at a 2? confidence level. This determination is in agreement with the value inferred from another well-studied DAV, G117-B15A. We now have two independent and consistent estimates of the mass of the axion obtained from DAVs, although additional studies of other pulsating white dwarfs are needed to confirm this value of the axion mass.

Córsico, A.H.; Althaus, L.G. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, (1900) La Plata (Argentina); Romero, A.D.; Kepler, S.O. [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre 91501-970, RS (Brazil); Mukadam, A.S. [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); García-Berro, E. [Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, 08860 Castelldefels (Spain); Isern, J. [Institut de Ciències de l'Espai (CSIC), Campus UAB, 08193 Bellaterra (Spain); Corti, M.A., E-mail: acorsico@fcaglp.unlp.edu.ar, E-mail: althaus@fcaglp.unlp.edu.ar, E-mail: aromero@fcaglp.unlp.edu.ar, E-mail: anjum@astro.washington.edu, E-mail: enrique.garcia-berro@upc.edu, E-mail: isern@ice.cat, E-mail: kepler@if.ufrgs.br, E-mail: mariela@fcaglp.fcaglp.unlp.edu.ar [Instituto Argentino de Radioastronomía (CCT-La Plata, CONICET), C.C. No. 5, 1894 Villa Elisa (Argentina)

2012-12-01

284

Simulating variably-saturated reactive transport of selenium and nitrogen in agricultural groundwater systems.  

PubMed

Selenium (Se) contamination in environmental systems has become a major issue in many regions world-wide during the previous decades, with both elevated and deficient Se concentrations in groundwater, surface water, soils and associated cultivated crops reported. To provide a tool that can assess baseline conditions and explore remediation strategies, this paper presents a numerical model capable of simulating the reactive transport of Se species in large-scale variably-saturated groundwater systems influenced by agricultural practices. Developed by incorporating a Se reaction module into the multi-species, variably-saturated reactive transport model UZF-RT3D, model features include near-surface Se cycling due to agricultural practices, oxidation-reduction reactions, and the inclusion of a nitrogen (N) cycle and reaction module due to the dependence of Se transformation and speciation on the presence of nitrate (NO?). Although the primary motivation is applying the model to large-scale systems, this paper presents applications to agricultural soil profile systems to corroborate the near-surface module processes that are vital in estimating mass loadings to the saturated zone in large-scale fate and transport studies. The first application jointly tests the Se and N modules for corn test plots receiving varying loadings of fertilizer, whereas the second application tests the N module for fertilized and unfertilized test plots. Results indicate that the model is successful in reproducing observed measurements of Se and NO? concentrations, particularly in lower soil layers and hence in regards to leaching. For the first application, the Ensemble Kalman Filter (EnKF) is used to condition model parameters, demonstrating the usefulness of the EnKF in real-world reactive transport systems. PMID:23584456

Bailey, Ryan T; Gates, Timothy K; Halvorson, Ardell D

2013-06-01

285

[The biorhythmology of primary and superinvasive opisthorchiasis. The seasonal variability in the relative mass of the parenchymatous and lymphoid organs in golden hamsters].  

PubMed

600 Golden Hamsters were divided into 3 groups: 1--free from opisthorchis invasion, 2--once infected, 3--repeatedly infected. Seasonal variability of liver, portal and mesentery lymph node and adrenal gland relative mass was investigated in winter, spring and autumn. Diurnal stereotype variability of parenchymatous and lymphoid organ relative mass is associated with a season and invasion number, and in a considerable degree is reflected in the meaning of average diurnal index. PMID:8984431

Shkliar, L G; Ginovker, A G

1995-01-01

286

Nevada Monitoring System to Assess Climate Variability and Change  

NASA Astrophysics Data System (ADS)

The Nevada System of Higher Education (University of Nevada Las Vegas, University of Nevada Reno and the Desert Research Institute) was awarded a multiyear NSF EPSCoR grant to support infrastructure associated with regional climate change research. The overall project is comprised of 5 components: education, cyberinfrastructure, policy, climate modeling and water/ecology. The water and ecology components are using their infrastructure funding for the assessment of climate variability and change on ecosystem function and hydrologic services. A series of 10 m tall towers are under construction and are being equipped with a wide array of sensors to monitor atmospheric, soil and plant parameters over time. The towers are located within the Mojave and Great Basin Deserts in two transects; the Mojave Desert transect is located in the southern Nevada Sheep Mountain Range and the Great Basin transect is located in the east central Nevada Snake Mountain Range. The towers are centrally positioned in well-defined vegetation zones. In southern Nevada these zones are represented by the following plant species: Creosote/Bursage (Creosotebush scrub zone); Blackbrush/Joshua Tree (Blackbrush zone); Pinyon/ Juniper (pygmy conifer zone), Ponderosa Pine (montane zone) and Bristlecone Pine (subalpine zone). The Snake Mountain transect incorporates the eastern and western valleys on both sides of the mountain range. The vegetation zones are represented by: Greasewood and mixed shrub (salt desert zone); Big Sage (sagebrush zone); Pinyon/Juniper (pygmy conifer zone); White/Douglas Fir, Ponderosa Pine and Aspen (montane zone); and Bristlecone/Limber Pine and Engelmann Spruce (subalpine zone). We are currently in the third year of funding with a goal of having the majority of towers fully operational by winter 2010. In close collaboration with our cyberinfrastructure component team, all data acquired from the transect monitoring stations will be made available to other researchers and the public in Nevada and elsewhere, cooperating agencies and organizations, and State of Nevada land managers.

Devitt, D. A.; Arnone, J.; Biondi, F.; Fenstermaker, L. F.; Saito, L.; Young, M.; Riddle, B.; Strachan, S. D.; Bird, B.; McCurdy, G.; Lyles, B. F.

2010-12-01

287

Mass  

SciTech Connect

In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

Quigg, Chris (Fermilab) [Fermilab

2007-12-05

288

23 CFR 810.308 - Approval of urban system nonhighway public mass transit projects.  

Code of Federal Regulations, 2014 CFR

...system nonhighway public mass transit projects. 810.308 Section 810.308 ...MASS TRANSIT AND SPECIAL USE HIGHWAY PROJECTS Federal-Aid Urban System Nonhighway Public Mass Transit Projects § 810.308 Approval of urban...

2014-04-01

289

23 CFR 810.308 - Approval of urban system nonhighway public mass transit projects.  

Code of Federal Regulations, 2010 CFR

...system nonhighway public mass transit projects. 810.308 Section 810.308 ...MASS TRANSIT AND SPECIAL USE HIGHWAY PROJECTS Federal-Aid Urban System Nonhighway Public Mass Transit Projects § 810.308 Approval of urban...

2010-04-01

290

23 CFR 810.308 - Approval of urban system nonhighway public mass transit projects.  

Code of Federal Regulations, 2011 CFR

...system nonhighway public mass transit projects. 810.308 Section 810.308 ...MASS TRANSIT AND SPECIAL USE HIGHWAY PROJECTS Federal-Aid Urban System Nonhighway Public Mass Transit Projects § 810.308 Approval of urban...

2011-04-01

291

23 CFR 810.308 - Approval of urban system nonhighway public mass transit projects.  

Code of Federal Regulations, 2012 CFR

...system nonhighway public mass transit projects. 810.308 Section 810.308 ...MASS TRANSIT AND SPECIAL USE HIGHWAY PROJECTS Federal-Aid Urban System Nonhighway Public Mass Transit Projects § 810.308 Approval of urban...

2012-04-01

292

23 CFR 810.308 - Approval of urban system nonhighway public mass transit projects.  

Code of Federal Regulations, 2013 CFR

...system nonhighway public mass transit projects. 810.308 Section 810.308 ...MASS TRANSIT AND SPECIAL USE HIGHWAY PROJECTS Federal-Aid Urban System Nonhighway Public Mass Transit Projects § 810.308 Approval of urban...

2013-04-01

293

A new real-time isokinetic dust mass monitoring system  

NASA Astrophysics Data System (ADS)

A new real-time dust mass monitor has been developed by combining an automatic isokinetic sampling probe with a tapered element oscillating microbalance (TEOM). Fly ash from a room temperature wind tunnel is sampled through the isokinetic sampler and collected on an astroquartz mat filter in the TEOM detector. The filter is first excited and oscillated at low frequency (about 200 Hz). As the particles deposit on the filter, the mass increase of the filter is reflected in a frequency reduction which yields the collected particle mass directly in real time. The TEOM detector normally has a high mass resolution (1 nanogram) and wide dynamic range (100,000 to 1,000,000). It is desensitized for high particle loading applications. Good agreement has been obtained between the mass collected through the isokinetic sampling system and the weight loss of the dust feeder, in real time. The body of information presented in this paper is directed to those concerned with particle emission and control in fossil fuel combustion systems.

Wang, J. C. F.; Patashnick, H.; Rupprecht, G.

1980-09-01

294

Mechanism studies of seasonal variability of dissolved oxygen in Mass Bay: A multi-scale FVCOM/UG-RCA application  

NASA Astrophysics Data System (ADS)

Long-term (1992-2010) water quality monitoring records reveal that the dissolved oxygen (DO) concentration in Mass Bay exhibits a well-defined seasonal cycle, highest in March-April and lowest in October. This pattern persists in all years with insignificant interannual variability. A multi-domain-nested coupled physical-biogeochemical model was developed and applied to simulate the DO field over the 16-year period 1995-2010. The model-computed DO and nitrogen concentrations were in good agreement with observations. An EOF analysis of the modeled DO field indicates that DO in Mass Bay features both well-defined seasonal and spatial modes. The magnitude and phase of the DO seasonal cycle vary more significantly in the southern bay than in the northern bay. Horizontal advection, which is connected to the western Gulf of Maine coastal currents, plays a dominant role in the DO variability in the northern bay. The southern bay features a well-defined local retention mechanism with a longer residence time. In this region, the DO variation is controlled predominantly by local biogeochemical processes. Since the photosynthetic minus respiration production of DO is always balanced to a large degree by the oxidation of organic matters, reaeration becomes a major driver for the seasonal cycle of DO.

Xue, Pengfei; Chen, Changsheng; Qi, Jianhua; Beardsley, Robert C.; Tian, Rucheng; Zhao, Liuzhi; Lin, Huichan

2014-03-01

295

Millihertz to hectohertz variability in low mass X-ray binaries as seen by XMM-Newton  

NASA Astrophysics Data System (ADS)

In the last two decades a detailed phenomenological picture of short-term variability in low-mass X-ray binaries has emerged mainly based on RXTE observations that cover energies above 3 keV. We are accomplishing a comprehensive study of archival XMM-Newton observations in timing or burst mode of more than ten black hole and more than thirty neutron star low-mass X-ray binaries to investigate the variability properties of these sources at softer energies. Here we present some results of this study, which will comprise a summary of the power density spectra and related time lags for different black hole X-ray binaries; a discussion of the energy dependence of the power spectral state that we found in the "plateau" state of GRS 1915+105 and the implications of this finding for the picture of the accretion geometry in black hole X-ray binaries; a presentation of the results of our waveform analysis and phase resolved spectral investigations of the millihertz quasi-periodic oscillations in 4U 1636-536 and a discussion on the implication of the potential thermonuclear burning mode based on its phase-resolved energy spectra.

Stiele, H.; Yu, W.

2014-07-01

296

Mass transfer effects on the unsteady mhd radiative- convective flow of a micropolar fluid past a vertical porous plate with variable heat and mass fluxes  

NASA Astrophysics Data System (ADS)

The problem of unsteady two-dimensional laminar flow of a viscous incompressible micropolar fluid past a vertical porous plate in the presence of a transverse magnetic field and thermal radiation with variable heat and mass fluxes is considered. The free stream velocity is subjected to exponentially increasing or decreasing small perturbations. A uniform magnetic field acts perpendicularly to a porous surface where a micropolar fluid is absorbed with a suction velocity varying with time. The Rosseland approximation is used to describe radiative heat transfer in the limit of optically thick fluids. The effects of the flow parameters and thermophysical properties on the velocity and temperature fields across the boundary layer are investigated. The effects of various parameters on the velocity, microrotation velocity, temperature, and concentration profiles are given graphically, and the values of the skin friction and couple stress coefficients are presented.

Reddy, M. Gnaneswara

2013-03-01

297

High-performance mass storage system for workstations  

NASA Technical Reports Server (NTRS)

Reduced Instruction Set Computer (RISC) workstations and Personnel Computers (PC) are very popular tools for office automation, command and control, scientific analysis, database management, and many other applications. However, when using Input/Output (I/O) intensive applications, the RISC workstations and PC's are often overburdened with the tasks of collecting, staging, storing, and distributing data. Also, by using standard high-performance peripherals and storage devices, the I/O function can still be a common bottleneck process. Therefore, the high-performance mass storage system, developed by Loral AeroSys' Independent Research and Development (IR&D) engineers, can offload a RISC workstation of I/O related functions and provide high-performance I/O functions and external interfaces. The high-performance mass storage system has the capabilities to ingest high-speed real-time data, perform signal or image processing, and stage, archive, and distribute the data. This mass storage system uses a hierarchical storage structure, thus reducing the total data storage cost, while maintaining high-I/O performance. The high-performance mass storage system is a network of low-cost parallel processors and storage devices. The nodes in the network have special I/O functions such as: SCSI controller, Ethernet controller, gateway controller, RS232 controller, IEEE488 controller, and digital/analog converter. The nodes are interconnected through high-speed direct memory access links to form a network. The topology of the network is easily reconfigurable to maximize system throughput for various applications. This high-performance mass storage system takes advantage of a 'busless' architecture for maximum expandability. The mass storage system consists of magnetic disks, a WORM optical disk jukebox, and an 8mm helical scan tape to form a hierarchical storage structure. Commonly used files are kept in the magnetic disk for fast retrieval. The optical disks are used as archive media, and the tapes are used as backup media. The storage system is managed by the IEEE mass storage reference model-based UniTree software package. UniTree software will keep track of all files in the system, will automatically migrate the lesser used files to archive media, and will stage the files when needed by the system. The user can access the files without knowledge of their physical location. The high-performance mass storage system developed by Loral AeroSys will significantly boost the system I/O performance and reduce the overall data storage cost. This storage system provides a highly flexible and cost-effective architecture for a variety of applications (e.g., realtime data acquisition with a signal and image processing requirement, long-term data archiving and distribution, and image analysis and enhancement).

Chiang, T.; Tang, Y.; Gupta, L.; Cooperman, S.

1993-01-01

298

Stability of orbits near large mass ratio binary systems  

NASA Astrophysics Data System (ADS)

With improved observational capabilities and techniques, an increasing number of exoplanets have been discovered to orbit in the vicinity of binary star systems. In this investigation, periodic motions near a large mass ratio binary are explored within the context of the circular restricted three-body problem. Specifically, stability analysis is used to explore the effect of the mass ratio on the structure of families of periodic orbits. Such analysis is useful in a variety of applications, including the determination of potentially stable exoplanet motions near a binary star.

Bosanac, Natasha; Howell, Kathleen C.; Fischbach, Ephraim

2015-02-01

299

Luminous blue variables are antisocial: their isolation implies that they are kicked mass gainers in binary evolution  

NASA Astrophysics Data System (ADS)

Based on their relatively isolated environments, we argue that luminous blue variables (LBVs) must be primarily the product of binary evolution, challenging the traditional single-star view wherein LBVs mark a brief transition between massive O-type stars and Wolf-Rayet (WR) stars. If the latter were true, then LBVs should be concentrated in young massive clusters like early O-type stars. This is decidedly not the case. Examining locations of LBVs in our Galaxy and the Magellanic Clouds reveals that, with only a few exceptions, LBVs systematically avoid clusters of O-type stars. In the Large Magellanic Cloud, LBVs are statistically much more isolated than O-type stars, and (perhaps most surprisingly) even more isolated than WR stars. This makes it impossible for LBVs to be single `massive stars in transition' to WR stars. Instead, we propose that massive stars and supernova (SN) subtypes are dominated by bifurcated evolutionary paths in interacting binaries, wherein most WR stars and Type Ibc supernovae (SNe Ibc) correspond to the mass donors, while LBVs (and their lower mass analogues like B[e] supergiants, which are even more isolated) are the mass gainers. In this view, LBVs are evolved massive blue stragglers. Through binary mass transfer, rejuvinated mass gainers get enriched, spun up, and sometimes kicked far from their clustered birth sites by their companion's SN. This scenario agrees better with LBVs exploding as SNe IIn in isolation, and it predicts that many massive runaway stars may be rapid rotators. Mergers or blue Thorne-Zytkow-like objects might also give rise to LBVs, but these scenarios may have a harder time explaining why LBVs avoid clusters.

Smith, Nathan; Tombleson, Ryan

2015-02-01

300

Multiple-Point Mass Flux Measurement System Using Rayleigh Scattering  

NASA Technical Reports Server (NTRS)

A multiple-point Rayleigh scattering diagnostic is being developed to provide mass flux measurements in gas flows. Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous density, temperature, and velocity measurements. Rayleigh scattered light from a focused 18 Watt continuous-wave laser beam is directly imaged through a solid Fabry-Perot etalon onto a CCD detector which permits spectral analysis of the light. The spatial resolution of the measurements is governed by the locations of interference fringes, which can be changed by altering the etalon characteristics. A prototype system has been used to acquire data in a Mach 0.56 flow to demonstrate feasibility of using this system to provide mass flux measurements. Estimates of measurement uncertainty and recommendations for system improvements are presented

Mielke, Amy F.; Elam, Kristie A.; Clem, Michelle M.

2009-01-01

301

The HD 5980 Multiple System: Masses and Evolutionary Status  

NASA Astrophysics Data System (ADS)

New spectroscopic observations of the LBV/WR multiple system HD 5980 in the Small Magellanic Cloud are used to address the question of the masses and evolutionary status of the two very luminous stars in the 19.3 day eclipsing binary system. Two distinct components of the N V 4944 Å line are detected in emission and their radial velocity variations are used to derive masses of 61 and 66 M ?, under the assumption that binary interaction effects on this atomic transition are negligible. We propose that this binary system is the product of quasi-chemically homogeneous evolution with little or no mass transfer. Thus, both of these binary stars may be candidates for gamma-ray burst progenitors or even pair instability supernovae. Analysis of the photospheric absorption lines belonging to the third-light object in the system confirm that it consists of an O-type star in a 96.56 day eccentric orbit (e = 0.82) around an unseen companion. The 5:1 period ratio and high eccentricities of the two binaries suggest that they may constitute a hierarchical quadruple system.

Koenigsberger, Gloria; Morrell, Nidia; Hillier, D. John; Gamen, Roberto; Schneider, Fabian R. N.; González-Jiménez, Nicolás; Langer, Norbert; Barbá, Rodolfo

2014-10-01

302

Petroleomics by electrospray ionization FT-ICR mass spectrometry coupled to partial least squares with variable selection methods: prediction of the total acid number of crude oils.  

PubMed

Negative-ion mode electrospray ionization, ESI(-), with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was coupled to a Partial Least Squares (PLS) regression and variable selection methods to estimate the total acid number (TAN) of Brazilian crude oil samples. Generally, ESI(-)-FT-ICR mass spectra present a power of resolution of ca. 500,000 and a mass accuracy less than 1 ppm, producing a data matrix containing over 5700 variables per sample. These variables correspond to heteroatom-containing species detected as deprotonated molecules, [M - H](-) ions, which are identified primarily as naphthenic acids, phenols and carbazole analog species. The TAN values for all samples ranged from 0.06 to 3.61 mg of KOH g(-1). To facilitate the spectral interpretation, three methods of variable selection were studied: variable importance in the projection (VIP), interval partial least squares (iPLS) and elimination of uninformative variables (UVE). The UVE method seems to be more appropriate for selecting important variables, reducing the dimension of the variables to 183 and producing a root mean square error of prediction of 0.32 mg of KOH g(-1). By reducing the size of the data, it was possible to relate the selected variables with their corresponding molecular formulas, thus identifying the main chemical species responsible for the TAN values. PMID:25068148

Terra, Luciana A; Filgueiras, Paulo R; Tose, Lílian V; Romão, Wanderson; de Souza, Douglas D; de Castro, Eustáquio V R; de Oliveira, Mirela S L; Dias, Júlio C M; Poppi, Ronei J

2014-10-01

303

Large variability of trace element mass fractions determined by ICP-SFMS in ice core samples from worldwide high altitude glaciers  

E-print Network

Large variability of trace element mass fractions determined by ICP-SFMS in ice core samples from and mass fractions of trace elements in melted acidified ice core samples measured by Inductively Coupled. Twenty trace elements (Ag, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Rb, Sb, Sn, Ti, Tl, U, V and Zn

Howat, Ian M.

304

Mass independent kinetic energy reducing inlet system for vacuum environment  

DOEpatents

A particle inlet system comprises a first chamber having a limiting orifice for an incoming gas stream and a micrometer controlled expansion slit. Lateral components of the momentum of the particles are substantially cancelled due to symmetry of the configuration once the laminar flow converges at the expansion slit. The particles and flow into a second chamber, which is maintained at a lower pressure than the first chamber, and then moves into a third chamber including multipole guides for electromagnetically confining the particle. The vertical momentum of the particles descending through the center of the third chamber is minimized as an upward stream of gases reduces the downward momentum of the particles. The translational kinetic energy of the particles is near-zero irrespective of the mass of the particles at an exit opening of the third chamber, which may be advantageously employed to provide enhanced mass resolution in mass spectrometry.

Reilly, Peter T. A. [Knoxville, TN

2010-12-14

305

Mass independent kinetic energy reducing inlet system for vacuum environment  

DOEpatents

A particle inlet system comprises a first chamber having a limiting orifice for an incoming gas stream and a micrometer controlled expansion slit. Lateral components of the momentum of the particles are substantially cancelled due to symmetry of the configuration once the laminar flow converges at the expansion slit. The particles and flow into a second chamber, which is maintained at a lower pressure than the first chamber, and then moves into a third chamber including multipole guides for electromagnetically confining the particle. The vertical momentum of the particles descending through the center of the third chamber is minimized as an upward stream of gases reduces the downward momentum of the particles. The translational kinetic energy of the particles is near-zero irrespective of the mass of the particles at an exit opening of the third chamber, which may be advantageously employed to provide enhanced mass resolution in mass spectrometry.

Reilly, Peter T.A.

2013-12-03

306

Mass independent kinetic energy reducing inlet system for vacuum environment  

DOEpatents

A particle inlet system comprises a first chamber having a limiting orifice for an incoming gas stream and a micrometer controlled expansion slit. Lateral components of the momentum of the particles are substantially cancelled due to symmetry of the configuration once the laminar flow converges at the expansion slit. The particles and flow into a second chamber, which is maintained at a lower pressure than the first chamber, and then moves into a third chamber including multipole guides for electromagnetically confining the particle. The vertical momentum of the particles descending through the center of the third chamber is minimized as an upward stream of gases reduces the downward momentum of the particles. The translational kinetic energy of the particles is near-zero irrespective of the mass of the particles at an exit opening of the third chamber, which may be advantageously employed to provide enhanced mass resolution in mass spectrometry.

Reilly, Peter T.A.

2014-05-13

307

Design challenges of variable magnification/variable object distance (VMODO) systems  

NASA Astrophysics Data System (ADS)

There are many applications for zoom systems which operate through a range of working distances while at the same time allowing multiple zoom levels or a smoothly varying magnification range. The problems involved in creating a system to support such applications are greater than either a fixed focal length system or a zoom system operating with an image at infinity. In this paper we will explore some of the optical and mechanical issues involved in such efforts, the tradeoffs between high optical performance and simple mechanical designs, and provide some of the solutions we've developed to address these issues.

Vogel, Steven H.; Alexay, Christopher C.; Palmer, Troy A.; Pollica, Naomi J.

2014-06-01

308

Variability in atmospheric particulates and meteorological effects on their mass concentrations over Delhi, India  

NASA Astrophysics Data System (ADS)

Simultaneous and continuous measurements of PM2.5 and PM10 along with other co-existent pollutants viz., black carbon (BC), CO, NO and NOx were carried out over Delhi with high resolution (5 min) datasets from 1st Sept. 2010 to 23rd Aug. 2012. Arithmetic mean mass concentrations of PM2.5 and PM10 were about 130 ± 103 and 222 ± 142 ?g m- 3 respectively during the entire measurement period, which are considerably higher than the annual averages of PM2.5 and PM10, stipulated by the National and International standards. It was noticed that the fine mode particles (PM2.5) were higher than the coarse mode particles (PM10-2.5) during post-monsoon (~ 89%), winter (~ 69%) and monsoon (~ 64%) periods; however, PM10-2.5 was higher (~ 22%) than PM2.5 during summer. Arithmetic mean mass concentrations of BC, CO, NO and NOx were about 7 ± 5 ?g m- 3, 2 ± 1 ppm, 17 ± 17 ppb and 30 ± 24 ppb, respectively. In the present study, highest fraction of BC (~ 6%) in PM2.5 mass was in winter, whereas the lowest fraction (~ 4%) was in summer. Relationships among PMs (particulate matters) and other pollutants indicated that the fine mode particles are highly correlated with BC (0.74) and CO (0.51). The effects of meteorological parameters on aerosols have been studied and a significant negative relationship (- 0.45) between mixing height (MH) and PM2.5 has been noticed. Higher correlation was during winter (- 0.55), however lower was in summer (- 0.16). Relation between visibility (VIS) and PM2.5 was higher during post-monsoon (- 0.85) and winter (- 0.78) when the visibility was around 2 km; however, it was relatively less correlated when VIS was greater than 2 km during summer and monsoon. Relationship between PM2.5 and relative humidity (RH) showed a significant negative correlation (- 0.56) for the entire study period. A positive correlation (0.32) was observed during the winter period with fine mode particles whereas negative correlation was seen with coarse mode particles during monsoon (- 0.70) and summer (- 0.51).

Tiwari, S.; Bisht, D. S.; Srivastava, A. K.; Pipal, A. S.; Taneja, A.; Srivastava, M. K.; Attri, S. D.

2014-08-01

309

Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment  

NASA Technical Reports Server (NTRS)

During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote sensing and climate research studies in dynamic aerosol-rich environments like Dongsha.

Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

2012-01-01

310

Variable gearing during locomotion in the human musculoskeletal system.  

PubMed

Human feet and toes provide a mechanism for changing the gear ratio of the ankle extensor muscles during a running step. A variable gear ratio could enhance muscle performance during constant-speed running by applying a more effective prestretch during landing, while maintaining the muscles near the high-efficiency or high-power portion of the force-velocity curve during takeoff. Furthermore, during acceleration, variable gearing may allow muscle contractile properties to remain optimized despite rapid changes in running speed. Forceplate and kinematic analyses of running steps show low gear ratios at touchdown that increase throughout the contact phase. PMID:8036513

Carrier, D R; Heglund, N C; Earls, K D

1994-07-29

311

Noise Levels Associated With New York City's Mass Transit Systems  

PubMed Central

Objectives. We measured noise levels associated with various forms of mass transit and compared them to exposure guidelines designed to protect against noise-induced hearing loss. Methods. We used noise dosimetry to measure time-integrated noise levels in a representative sample of New York City mass transit systems (subways, buses, ferries, tramway, and commuter railways) aboard transit vehicles and at vehicle boarding platforms or terminals during June and July 2007. Results. Of the transit types evaluated, subway cars and platforms had the highest associated equivalent continuous average (Leq) and maximum noise levels. All transit types had Leq levels appreciably above 70 A-weighted decibels, the threshold at which noise-induced hearing loss is considered possible. Conclusions. Mass transit noise exposure has the potential to exceed limits recommended by the World Health Organization and the US Environmental Protection Agency and thus cause noise-induced hearing loss among riders of all forms of mass transit given sufficient exposure durations. Environmental noise–control efforts in mass transit and, in cases in which controls are infeasible, the use of personal hearing protection would benefit the ridership's hearing health. PMID:19542046

Gershon, Robyn R. M.; Zeltser, Marina; Canton, Allison; Akram, Muhammad

2009-01-01

312

Mass-Independent Fractionation of Mercury in Hydrothermal Systems  

NASA Astrophysics Data System (ADS)

Experimental results indicate that mass-independent fractionation (MIF) of mercury occurs during both photochemical reduction of Hg2+ and photochemical demethylation of methyl-mercury. In aqueous systems, the photochemical reduction of Hg2+aq to Hg0aq and subsequent evasion of Hg0g preferentially retains the odd mass isotopes of Hg in the aqueous phase and releases the even mass isotopes of Hg in Hg0g. MIF of Hg has been observed recently in marine and freshwater fish, soils, peat, mosses and sediments. We investigated Hg in modern volcanic-hydrothermal systems to evaluate whether major earth reservoirs carry a MIF signature. Hydrothermal systems driven by mantle-derived volcanism are a major natural source of Hg to the atmosphere and may represent the isotopic composition of deep geological reservoirs. We analyzed fluid and siliceous sinter samples from hot springs in the Yellowstone Plateau volcanic field and vent chimney precipitates from the Guaymas Basin sea-floor rift. In all of the analyzed fluid and sinter samples from Ojo Caliente hot spring in Yellowstone, we observed a small but significant positive MIF (?199Hg = 0.13‰ ± 0.06‰, 2SD). No significant MIF was measured in any of the sea-floor rift samples from Guaymas Basin. In Ojo Caliente, Hg is both lost from the fluids and fractionated mass-dependently along a flow path from the hot spring vent to the outflow channel. We suggest that Hg loss and mass-dependent fractionation occur in this system due to volatilization of Hg0aq to Hg0g. In contrast, because all of the samples measured from Ojo Caliente exhibited approximately the same degree of MIF, it is not likely that measurable photochemical reduction of Hg is occurring in this system on the short timescale (i.e., minutes) of fluid discharge. Instead, we suggest that either (1) some portion of the Hg in the system was photochemically reduced at the earth's surface in the past and transported back to the subsurface (perhaps by groundwater infiltration) or (2) Hg is leached into the hydrothermal system from sediments containing an MIF signature. The lack of MIF in vent chimney samples from Guaymas Basin suggests that because Hg in that sea-floor rift hydrothermal system is isolated from light, it has not been affected by the photochemical reactions that cause MIF of Hg.

Sherman, L. S.; Blum, J. D.; Nordstrom, D. K.; McCleskey, R. B.; Barkay, T.; Vetriani, C.

2008-12-01

313

Energy efficient fixed-priority scheduling for real-time systems on variable voltage processors  

Microsoft Academic Search

Energy consumption has become an increasingly important consideration in designing many real-time embedded systems. Variable voltage processors, if used properly, can dramatically reduce such system energy consumption. In this paper, we present a technique to determine voltage settings for a variable voltage processor that utilizes a fixed priority assignment to schedule jobs. Our approach also produces the minimum constant voltage

Gang Quan; Xiaobo Hu

2001-01-01

314

Optimal unit sizing of cogeneration systems in consideration of uncertain energy demands as continuous random variables  

Microsoft Academic Search

An optimal unit sizing method for cogeneration systems is proposed using energy demands as continuous random variables. In this method, design variables such as equipment capacities and maximum contract utility demands are determined together with the systems' operational strategies so as to minimize an expected value of the annual total cost subject to the satisfaction of all the possible energy

Satoshi Gamou; Ryohei Yokoyama; Koichi Ito

2002-01-01

315

Bridging the gap between product lines and systems engineering. An experience in variability management for  

E-print Network

Bridging the gap between product lines and systems engineering. An experience in variability.dauron@renault.com ABSTRACT We present in this paper an experience in modeling a family of parking brake systems, with shared the adoption of a product line approach and of variability mod- eling techniques, outside of a pure

Paris-Sud XI, Université de

316

Tidally-Forced Flow Variability Within Mid-Ocean Ridge Hydrothermal Systems: Models and Measurement Techniques  

E-print Network

black smoker hydrothermal vents. The first technique I develop is based on passive acoustic measurementsTidally-Forced Flow Variability Within Mid-Ocean Ridge Hydrothermal Systems: Models and Measurement of Washington Abstract Tidally-Forced Flow Variability Within Mid-Ocean Ridge Hydrothermal Systems: Models

Crone, Timothy J.

317

Variable speed integrated generator VSIG as a modern controlled and decoupled generation system of electrical power  

Microsoft Academic Search

The paper presents variable speed generation system producing standardised 400 V\\/230 V\\/50 Hz voltage. An internal combustion engine (diesel engine) is driving a permanent magnet axial flux generator. An AC\\/AC power electronic system converts variable frequency and amplitude the permanent magnet generator AC voltage to the standardised AC voltage. The axial flux generator is very short, light, shaftless and bearingless.

Wlodzimierz Koczara; N. Al Khayat

2005-01-01

318

Steps Toward Accommodating Variable Position Tracking Accuracy in a Mobile Augmented Reality System  

E-print Network

Steps Toward Accommodating Variable Position Tracking Accuracy in a Mobile Augmented Reality System. This is es- pecially problematic for mobile augmented reality systems, which ideally require extremely level of accuracy. While it is possible to ignore variable positional accuracy in an augmented reality

Hollerer, Tobias

319

Control of variable pitch, variable speed wind turbine in weak grid systems  

Microsoft Academic Search

In the case of operating in a weak grid system, when wind power becomes a significant portion of the power system or even the sole energy source, the wind power generator and its converter are expected to help maintain the grid voltage amplitude and frequency, operating like the conventional large synchronous generator (SG). The grid-side converter needs to work as

Xibo Yuan; Jianyun Chai; Yongdong Li

2010-01-01

320

Factors influencing variability in the infiltration of PM2.5 mass and its components  

NASA Astrophysics Data System (ADS)

The infiltration of particles into homes can vary seasonally, between homes in a community and between communities. However, few studies have examined the day to day variability across multiple homes. We used continuous data collected from a 2-year (2005-2006) personal exposure study conducted in Windsor, ON to estimate daily infiltration factors (Finf) for fine particulate matter (PM2.5), Black Carbon (BC), and ultrafine particles (UFP) as well as the ambient personal exposure factor (Fpex) for PM2.5. In addition, the daily ambient and non-ambient generated components of indoor and personal concentrations were estimated. Median daily Finf estimates ranged from 0.26 to 0.36 across seasons for PM2.5; from 0.28 to 0.59 for BC; and from 0.15 to 0.26 for UFP. Median daily Fpex estimates ranged from 0.24 to 0.31 across seasons. Daily PM2.5 and UFP Finf and Fpex estimates were higher in summer than winter, although BC showed the opposite trend. Predictors of daily infiltration were typically related to window-opening behaviours, air conditioning, meteorological variables, and home age. In addition, use of electrostatic precipitators and stand alone air cleaners was associated with significantly reduced infiltration factors, indicating that these devices may provide a cost effective mechanism of reducing human exposures to particles of ambient origin. The majority of indoor PM2.5 (median 57-73%) and indoor BC (median 90-100%) was of ambient origin across seasons, while both personal PM2.5 and indoor UFPs had significant non-ambient contributions (median 60-65%). Factors that were found to increase non-ambient particle concentrations were typically related to cooking, candle use, supplemental heating, cleaning, and number of people in the home. Factors that were found to decrease non-ambient particle concentrations were open windows, and air cleaner use. This work has several implications to both epidemiologic studies and risk management. A better understanding of the factors influencing Finf and Fpex can improve exposure assessment and contribute to reduced exposure misclassification in epidemiologic studies. Furthermore, by increasing our knowledge of non-ambient and ambient exposures, risk associated with PM exposure can be managed more effectively.

MacNeill, M.; Wallace, L.; Kearney, J.; Allen, R. W.; Van Ryswyk, K.; Judek, S.; Xu, X.; Wheeler, A.

2012-12-01

321

Miniature mass spectrometer systems based on a microengineered quadrupole filter.  

PubMed

Two miniature mass spectrometer systems based on a microengineered quadrupole mass filter have been developed. One of the instruments has a footprint of 27 cm x 20 cm and is intended for laboratory use when space is at a premium. The other is portable and intended for use in the field. It is battery powered, weighs 14.9 kg, and is housed in a rugged case. This is the first example of a portable mass spectrometer incorporating an analyzer fabricated using microelectromechanical systems (MEMS) techniques. The starting material for construction of the filters is a bonded silicon on insulator substrate, which is selectively etched using batch processing techniques to form coupling optics and springs that accurately hold 0.5 mm diameter stainless steel rods in the required geometry. Assembled filters measure 35 mm x 6 mm x 1.5 mm and are mounted, together with an ion source and channeltron detector, in small, interchangeable cartridges, which plug into a 220 cm(3) vacuum chamber. Recovery from accidental contamination or when servicing is required can be achieved within 5-10 min, as the cartridge is easily exchanged with a spare. A potential application to environmental monitoring has been investigated. The headspace above water spiked with dibutyl mercaptan was sampled with a solid phase microextraction (SPME) fiber, which was then injected directly into the vacuum chamber of the mass spectrometer. Using this method, the limit of detection was found to be approximately 5 ppm for a 15 s sampling period. PMID:20108919

Malcolm, Andrew; Wright, Steven; Syms, Richard R A; Dash, Neil; Schwab, Marc-André; Finlay, Alan

2010-03-01

322

Saponification reaction system: a detailed mass transfer coefficient determination.  

PubMed

The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach. PMID:25830982

Pe?ar, Darja; Goršek, Andreja

2015-01-01

323

Experimental investigation of a variable speed constant frequency electric generating system from a utility perspective  

NASA Technical Reports Server (NTRS)

As efforts are accelerated to improve the overall capability and performance of wind electric systems, increased attention to variable speed configurations has developed. A number of potentially viable configurations have emerged. Various attributes of variable speed systems need to be carefully tested to evaluate their performance from the utility points of view. With this purpose, the NASA experimental variable speed constant frequency (VSCF) system has been tested. In order to determine the usefulness of these systems in utility applications, tests are required to resolve issues fundamental to electric utility systems. Legitimate questions exist regarding how variable speed generators will influence the performance of electric utility systems; therefore, tests from a utility perspective, have been performed on the VSCF system and an induction generator at an operating power level of 30 kW on a system rated at 200 kVA and 0.8 power factor.

Herrera, J. I.; Reddoch, T. W.; Lawler, J. S.

1985-01-01

324

The Effect of Pressure Difference Control on Hydraulic Stability in a Variable Flow Air Conditioning System  

E-print Network

This paper analyzes the effects of different pressure difference control methods on hydraulic stability in a variable flow air conditioning system when it is applied to different air conditioning water systems. According to control method and water...

Zhang, Z.; Fu, Y.; Chen, Y.

2006-01-01

325

Experimental investigation of a variable speed constant frequency electric generating system from a utility perspective  

NASA Astrophysics Data System (ADS)

As efforts are accelerated to improve the overall capability and performance of wind electric systems, increased attention to variable speed configurations has developed. A number of potentially viable configurations have emerged. Various attributes of variable speed systems need to be carefully tested to evaluate their performance from the utility points of view. With this purpose, the NASA experimental variable speed constant frequency (VSCF) system has been tested. In order to determine the usefulness of these systems in utility applications, tests are required to resolve issues fundamental to electric utility systems. Legitimate questions exist regarding how variable speed generators will influence the performance of electric utility systems; therefore, tests from a utility perspective, have been performed on the VSCF system and an induction generator at an operating power level of 30 kW on a system rated at 200 kVA and 0.8 power factor.

Herrera, J. I.; Reddoch, T. W.; Lawler, J. S.

1985-05-01

326

Variable Temperature (1.6–300 K) X-Band EPR System with a Variable Cavity Coupler  

Microsoft Academic Search

A variable temperature (1.6–300 K) electron paramagnetic resonance (EPR) X-band spectrometer is described. The spectrometer is a Varian V-4502 EPR spectrometer using a V-4500–42 X-band microwave bridge and a V-K3525 superheterodyne accessory. The Dewar system is an Andonian Associates Cryostat with a 4.43 cm i.d. sample area. The sample cavity resonates in the TE102 rectangular mode. The coupling of the

J. A. MacKinnon

1972-01-01

327

On the Inversion for Mass (Re)Distribution from Global (Time-Variable) Gravity Field  

NASA Technical Reports Server (NTRS)

The well-known non-uniqueness of the gravitational inverse problem states the following: The external gravity field, even if completely and exactly known, cannot Uniquely determine the density distribution of the body that produces the gravity field. This is an intrinsic property of a field that obeys the Laplace equation, as already treated in mathematical as well as geophysical literature. In this paper we provide conceptual insight by examining the problem in terms of spherical harmonic expansion of the global gravity field. By comparing the multipoles and the moments of the density function, we show that in 3-S the degree of knowledge deficiency in trying to inversely recover the density distribution from external gravity field is (n+l)(n+2)/2 - (2n+l) = n(n-1)/2 for each harmonic degree n. On the other hand, on a 2-D spherical shell we show via a simple relationship that the inverse solution of the surface density distribution is unique. The latter applies quite readily in the inversion of time-variable gravity signals (such as those observed by the GRACE space mission) where the sources over a wide range of the scales largely come from the Earth's Surface.

Chao, Benjamin F.

2004-01-01

328

Compliant motion control using variable structure PID control system  

Microsoft Academic Search

This paper describes the design of a variable structure PID controller using genetic algorithms for compliant motion control. This VSPID has a structure similar to that of a simple PID controller where the PD mode is used to speed up response, whereas the PI mode is applied to eliminate the steady state offset. Flexible changes of the controller modes and

Ossama Ismail; Wassim Bedwani

2001-01-01

329

Adaptive variable structure control system with free chattering  

Microsoft Academic Search

High frequency chattering is undesirable in many cases. The reluctance of using variable structure control (VSC) is mainly due to the concern of excess chatter. This paper presents two methods for solving the existing control chattering problem. The plant augmentation method introduces the strategy for solving the existing problem by augmenting the plant with a pure integrator. The adaptive VSC

Tarek M. M. Nasab

1999-01-01

330

The sympathetic nervous system's role in regulating blood pressure variability  

Microsoft Academic Search

This article focuses on how sympathetic nerve activity (SNA) contributes to the variability seen in blood pressure. Specifically, it examines the following questions: why do oscillations occur at certain frequencies, why do only certain frequencies of oscillations in SNA induce oscillations in the vasculature, and what may be the functional purpose of these oscillations.

Simon C. Malpas; Bridget L. Leonard; Sarah-Jane Guild; John V. Ringwood; Michael Navakatikyan; Paul C. Austin; Geoffrey A. Head; Don E. Burgess

2001-01-01

331

Enhancing adoption of site-specific variable rate sprinkler systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

More than twenty years of private and public research on site-specific variable-rate sprinkler irrigation (SS-VRI) has resulted in very limited commercial adoption of the technology. Documented and proven water conservation strategies using site-specific irrigation are quite limited, and its cost-ef...

332

Adoption of site-specific variable rate sprinkler irrigation systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

More than twenty years of private and public research on site-specific variable-rate sprinkler irrigation (SS-VRI) technology has resulted in limited commercial adoption of the technology. Competing patents, liability and proprietary software have affected industry’s willingness to move into a new t...

333

Improvement of Diesel Engine Performance by Variable Valve Train System  

Microsoft Academic Search

The effects of variable valve timing and lift are studied in order to improve the thermal efficiency of a diesel engine, while maintaining low emission levels. At high load conditions, early closing of one of the intake valves or early intake valve opening realizes an enhancement of swirl intensity without increased pumping losses, and retarded intake valve closing reduces the

T Tomoda; T Ogawa; H Ohki; T Kogo; K Nakatani; E Hashimoto

2010-01-01

334

Fourth NASA Goddard Conference on Mass Storage Systems and Technologies  

NASA Technical Reports Server (NTRS)

This report contains copies of all those technical papers received in time for publication just prior to the Fourth Goddard Conference on Mass Storage and Technologies, held March 28-30, 1995, at the University of Maryland, University College Conference Center, in College Park, Maryland. This series of conferences continues to serve as a unique medium for the exchange of information on topics relating to the ingestion and management of substantial amounts of data and the attendant problems involved. This year's discussion topics include new storage technology, stability of recorded media, performance studies, storage system solutions, the National Information infrastructure (Infobahn), the future for storage technology, and lessons learned from various projects. There also will be an update on the IEEE Mass Storage System Reference Model Version 5, on which the final vote was taken in July 1994.

Kobler, Benjamin (editor); Hariharan, P. C. (editor)

1994-01-01

335

Mass spectrometer. [On Space Transportation System 2 Flight  

NASA Technical Reports Server (NTRS)

The quadrupole Mass Spectrometer of the Induced Environment Contamination Monitor (IECM) operates in the range from 2 to 150 amu. It is pointed out that the Mass Spectrometer on STS-2 performed very well. It was found that the column density of H2O effluent from the Shuttle reached a maximum of 1 x 10 to the 13th per sq cm at 7 hr, 30 min and decreased by a factor of 7.5 during the subsequent 40 hrs. The count rate response of H2O could be correlated with mission-related events, taking into account the dumping of supply water, the operation of the Flash Evaporator System, and the firing of a primary reaction control system engine.

Miller, E. R.; Carignan, G. R.

1983-01-01

336

The automation of an inlet mass flow control system  

NASA Technical Reports Server (NTRS)

The automation of a closed-loop computer controlled system for the inlet mass flow system (IMFS) developed for a wind tunnel facility at Langley Research Center is presented. This new PC based control system is intended to replace the manual control system presently in use in order to fully automate the plug positioning of the IMFS during wind tunnel testing. Provision is also made for communication between the PC and a host-computer in order to allow total animation of the plug positioning and data acquisition during the complete sequence of predetermined plug locations. As extensive running time is programmed for the IMFS, this new automated system will save both manpower and tunnel running time.

Supplee, Frank; Tcheng, Ping; Weisenborn, Michael

1989-01-01

337

Grand challenges in mass storage: A system integrator's perspective  

NASA Technical Reports Server (NTRS)

The grand challenges are the following: to develop more innovation in approach; to expand the I/O barrier; to achieve increased volumetric efficiency and incremental cost improvements; to reinforce the 'weakest link' software; to implement improved architectures; and to minimize the impact of self-destructing technologies. Mass storage is defined as any type of storage system exceeding 100 GBytes in total size, under the control of a centralized file management scheme. The topics covered are presented in viewgraph form.

Mintz, Dan; Lee, Richard

1993-01-01

338

Control system and method for a power delivery system having a continuously variable ratio transmission  

DOEpatents

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for minimum fuel consumption. CVT ratio is controlled as a function of commanded power or torque and measured load, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristic for any load placed on the engine.

Frank, Andrew A. (1034 Hillside Ave., Madison, WI 53705)

1984-01-01

339

Control system and method for a power delivery system having a continuously variable ratio transmission  

DOEpatents

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for minimum fuel consumption. CVT ratio is controlled as a function of commanded power or torque and measured load, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristic for any load placed on the engine. 4 figs.

Frank, A.A.

1984-07-10

340

X-RAY DETERMINATION OF THE VARIABLE RATE OF MASS ACCRETION ONTO TW HYDRAE  

SciTech Connect

Diagnostics of electron temperature (T{sub e} ), electron density (n{sub e} ), and hydrogen column density (N{sub H}) from the Chandra High Energy Transmission Grating spectrum of He-like Ne IX in TW Hydrae (TW Hya), in conjunction with a classical accretion model, allow us to infer the accretion rate onto the star directly from measurements of the accreting material. The new method introduces the use of the absorption of Ne IX lines as a measure of the column density of the intervening, accreting material. On average, the derived mass accretion rate for TW Hya is 1.5 Multiplication-Sign 10{sup -9} M{sub Sun} yr{sup -1}, for a stellar magnetic field strength of 600 G and a filling factor of 3.5%. Three individual Chandra exposures show statistically significant differences in the Ne IX line ratios, indicating changes in N{sub H}, T{sub e} , and n{sub e} by factors of 0.28, 1.6, and 1.3, respectively. In exposures separated by 2.7 days, the observations reported here suggest a five-fold reduction in the accretion rate. This powerful new technique promises to substantially improve our understanding of the accretion process in young stars.

Brickhouse, N. S.; Cranmer, S. R.; Dupree, A. K.; Guenther, H. M.; Wolk, S. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Luna, G. J. M. [Current address: Instituto de Astronomia y Fisica del Espacio (IAFE), Buenos Aires (Argentina)

2012-12-01

341

General hidden-variable model for a two-qubit system  

NASA Astrophysics Data System (ADS)

We generalize Bell's hidden-variable model describing the singlet state of a two-qubit system by extending it to arbitrary states and observables. As in the original work, we assume a uniform, state-independent probability distribution for the hidden variables which are identified with the unit vectors of a three-dimensional real space. By slightly modifying our model, we provide also a minimal hidden variable description of the two-qubit system, relying on a single hidden variable. We discuss the main features and the implications of the model.

Ghirardi, GianCarlo; Romano, Raffaele

2012-04-01

342

Eighth Goddard Conference on Mass Storage Systems and Technologies in Cooperation with the Seventeenth IEEE Symposium on Mass Storage Systems  

NASA Technical Reports Server (NTRS)

This document contains copies of those technical papers received in time for publication prior to the Eighth Goddard Conference on Mass Storage Systems and Technologies which is being held in cooperation with the Seventeenth IEEE Symposium on Mass Storage Systems at the University of Maryland University College Inn and Conference Center March 27-30, 2000. As one of an ongoing series, this Conference continues to provide a forum for discussion of issues relevant to the management of large volumes of data. The Conference encourages all interested organizations to discuss long term mass storage requirements and experiences in fielding solutions. Emphasis is on current and future practical solutions addressing issues in data management, storage systems and media, data acquisition, long term retention of data, and data distribution. This year's discussion topics include architecture, future of current technology, new technology with a special emphasis on holographic storage, performance, standards, site reports, vendor solutions. Tutorials will be available on stability of optical media, disk subsystem performance evaluation, I/O and storage tuning, functionality and performance evaluation of file systems for storage area networks.

Kobler, Benjamin (Editor); Hariharan, P. C. (Editor)

2000-01-01

343

The Stability of the Orbits of Earth-mass Planets in and near the Habitable Zones of Known Exoplanetary Systems  

E-print Network

We have shown that Earth-mass planets could survive in variously restricted regions of the habitable zones (HZs) of most of a sample of nine of the 93 main-sequence exoplanetary systems confirmed by May 2003. In a preliminary extrapolation of our results to the other systems, we estimate that roughly a third of the 93 systems might be able to have Earth-mass planets in stable, confined orbits somewhere in their HZs. Clearly, these systems should be high on the target list for exploration for terrestrial planets. We have reached this conclusion by launching putative Earth-mass planets in various orbits and following their fate with a mixed-variable symplectic integrator.

Barrie W Jones; David R Underwood; P Nick Sleep

2003-05-27

344

A mass storage system for supercomputers based on Unix  

NASA Technical Reports Server (NTRS)

The authors present the design, implementation, and utilization of a large mass storage subsystem (MSS) for the numerical aerodynamics simulation. The MSS supports a large networked, multivendor Unix-based supercomputing facility. The MSS at Ames Research Center provides all processors on the numerical aerodynamics system processing network, from workstations to supercomputers, the ability to store large amounts of data in a highly accessible, long-term repository. The MSS uses Unix System V and is capable of storing hundreds of thousands of files ranging from a few bytes to 2 Gb in size.

Richards, J.; Kummell, T.; Zarlengo, D. G.

1988-01-01

345

Complex systems and the technology of variability analysis  

Microsoft Academic Search

Characteristic patterns of variation over time, namely rhythms, represent a defining feature of complex systems, one that is synonymous with life. Despite the intrinsic dynamic, interdependent and nonlinear relationships of their parts, complex biological systems exhibit robust systemic stability. Applied to critical care, it is the systemic properties of the host response to a physiological insult that manifest as health

Andrew JE Seely; Peter T Macklem

2004-01-01

346

Interannual to decadal oxygen variability in the mid-depth water masses of the eastern North Atlantic  

NASA Astrophysics Data System (ADS)

The detection of multi-decadal trends in the oceanic oxygen content and its possible attribution to global warming is protracted by the presence of a substantial amount of interannual to decadal variability, which hitherto is poorly known and characterized. Here we address this gap by studying interannual to decadal changes of the oxygen concentration in the Subpolar Mode Water (SPMW), the Intermediate Water (IW) and the Mediterranean Outflow Water (MOW) in the eastern North Atlantic. We use data from a hydrographic section located in the eastern North Atlantic at about 48°N repeated 12 times over a period of 19 years from 1993 through 2011, with a nearly annual resolution up to 2005. Despite a substantial amount of year-to-year variability, we observe a long-term decrease in the oxygen concentration of all three water masses, with the largest changes occurring from 1993 to 2002. During that time period, the trends were mainly caused by a contraction of the subpolar gyre associated with a northwestward shift of the Subpolar Front (SPF) in the eastern North Atlantic. This caused SPMW to be ventilated at lighter densities and its original density range being invaded by subtropical waters with substantially lower oxygen concentrations. The contraction of the subpolar gyre reduced also the penetration of IW of subpolar origin into the region in favor of an increased northward transport of IW of subtropical origin, which is also lower in oxygen. The long-term oxygen changes in the MOW were mainly affected by the interplay between circulation and solubility changes. Besides the long-term signals, mesoscale variability leaves a substantial imprint as well, affecting the water column over at least the upper 1000 m and laterally by more than 400 km. Mesoscale eddies induced changes in the oxygen concentration of a magnitude that can substantially alias analyses of long-term changes based on repeat hydrographic data that are being collected at intervals of typically 10 years.

Stendardo, Ilaria; Kieke, Dagmar; Rhein, Monika; Gruber, Nicolas; Steinfeldt, Reiner

2015-01-01

347

A {approx} 40 YEAR VARIABILITY CYCLE IN THE LUMINOUS BLUE VARIABLE/WOLF-RAYET BINARY SYSTEM HD 5980?  

SciTech Connect

The massive Wolf-Rayet stellar system HD 5980 in the Small Magellanic Cloud entered a sudden and brief {approx} 1-3 mag eruptive state in the mid-1990s. The cause of the instability is not yet understood, but mechanisms similar to those in luminous blue variables are suspected. Using a previously unreported set of spectroscopic data obtained in 1955-1967 and recently acquired optical and HST/STIS spectra, we find that (1) the brief eruptions of 1993 and 1994 occurred at the beginning of an extended ({approx} decades) high state of activity characterized by large emission-line intensities; (2) the level of activity is currently subsiding; and (3) another strong emission-line episode appears to have occurred between 1960 and 1965, suggesting the possibility that the long-term cyclical variability may be recurrent on a {approx} 40 year timescale. These characteristics suggest the possible classification of HD 5980 as an S Doradus-type variable. The effects due to binary interactions in the system are discussed, and we tentatively suggest that the short duration and relatively hot spectral type (WN11/B1.5I) observed during maximum in the visual light curve may be attributed to these interactions.

Koenigsberger, Gloria [Instituto de Ciencias FIsicas, Universidad Nacional Autonoma de Mexico, Av. Universidad s/n, Cuernavaca, Mor. 62210 (Mexico); Georgiev, Leonid [Instituto de AstronomIa, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-264, Mexico D.F. 04510 (Mexico); Hillier, D. John [Department of Astronomy, 3941 O'Hara Street, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Morrell, Nidia [Las Campanas Observatory, The Carnegie Observatories, Colina El Pino s/n, Casillas 601, La Serena (Chile); Barba, Rodolfo [Departamento de Fisica, Universidad de la Serena, Benavente 980, La Serena (Chile); Gamen, Roberto, E-mail: gloria@astro.unam.m, E-mail: georgiev@astro.unam.m, E-mail: djh@rosella.phyast.pitt.ed, E-mail: nmorrell@lco.c, E-mail: rbarba@dfuls.c, E-mail: rgamen@gmail.co [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, and Instituto de Astrofisica de La Plata (CCT La Plata-CONICET), Paseo del Bosque S/N, B1900FWA, La Plata (Argentina)

2010-06-15

348

System Modeling of Lunar Oxygen Production: Mass and Power Requirements  

NASA Technical Reports Server (NTRS)

A systems analysis tool for estimating the mass and power requirements for a lunar oxygen production facility is introduced. The individual modeling components involve the chemical processing and cryogenic storage subsystems needed to process a beneficiated regolith stream into liquid oxygen via ilmenite reduction. The power can be supplied from one of six different fission reactor-converter systems. A baseline system analysis, capable of producing 15 metric tons of oxygen per annum, is presented. The influence of reactor-converter choice was seen to have a small but measurable impact on the system configuration and performance. Finally, the mission concept of operations can have a substantial impact upon individual component size and power requirements.

Steffen, Christopher J.; Freeh, Joshua E.; Linne, Diane L.; Faykus, Eric W.; Gallo, Christopher A.; Green, Robert D.

2007-01-01

349

The NEEDS Data Base Management and Archival Mass Memory System  

NASA Technical Reports Server (NTRS)

A Data Base Management System and an Archival Mass Memory System are being developed that will have a 10 to the 12th bit on-line and a 10 to the 13th off-line storage capacity. The integrated system will accept packetized data from the data staging area at 50 Mbps, create a comprehensive directory, provide for file management, record the data, perform error detection and correction, accept user requests, retrieve the requested data files and provide the data to multiple users at a combined rate of 50 Mbps. Stored and replicated data files will have a bit error rate of less than 10 to the -9th even after ten years of storage. The integrated system will be demonstrated to prove the technology late in 1981.

Bailey, G. A.; Bryant, S. B.; Thomas, D. T.; Wagnon, F. W.

1980-01-01

350

Numerical Investigation of Multiple-, Interacting-Scale Variable-Density Ground Water Flow Systems  

NASA Astrophysics Data System (ADS)

The goal of our study is to elucidate the nonlinear processes that are important for multiple-, interacting-scale flow and solute transport in subsurface environments. In particular, we are focusing on the influence of small-scale instability development on variable-density ground water flow behavior in large-scale systems. Convective mixing caused by these instabilities may mix the fluids to a greater extent than would be the case with classical, Fickian dispersion. Most current numerical schemes for interpreting field-scale variable-density flow systems do not explicitly account for the complexities caused by small-scale instabilities and treat such processes as "lumped" Fickian dispersive mixing. Such approaches may greatly underestimate the mixing behavior and misrepresent the overall large-scale flow field dynamics. The specific objectives of our study are: (i) to develop an adaptive (spatial and temporal scales) three-dimensional numerical model that is fully capable of simulating field-scale variable-density flow systems with fine resolution (~1 cm); and (ii) to evaluate the importance of scale-dependent process interactions by performing a series of simulations on different problem scales ranging from laboratory experiments to field settings, including an aquifer storage and freshwater recovery (ASR) system similar to those planned for the Florida Everglades and in-situ contaminant remediation systems. We are examining (1) methods to create instabilities in field-scale systems, (2) porous media heterogeneity effects, and (3) the relation between heterogeneity characteristics (e.g., permeability variance and correlation length scales) and the mixing scales that develop for varying degrees of unstable stratification. Applications of our work include the design of new water supply and conservation measures (e.g., ASR systems), assessment of saltwater intrusion problems in coastal aquifers, and the design of in-situ remediation systems for aquifer restoration. We present preliminary model results for high-resolution simulation of variable-density flow and transport in homogeneous and heterogeneous porous media. We explicitly solve the three-dimensional advection equation using mass-conservative, flux-integral techniques and finite-volume formulations that provide unrestricted time-step capabilities similar to those associated with semi-Lagrangian methods. Our implementation of B. P. Leonard's MACHO (Multidimensional Advective-Conservative Hybrid Operator) and COSMIC (Conservative Operator Splitting for Multidimensions with Inherent Constancy) methods is an Nth-order (e.g., 7th-order or higher) advection scheme that significantly reduces numerical dispersion and can be adapted spatially and temporally as the simulation progresses. The ability of these higher-order methods to yield accurate, nonoscillatory concentration profiles is illustrated and compared to traditional implicit solution methods such as central and upwind differencing, and van Leer flux limiters. We also show preliminary results from our implementation of adaptive mesh refinement (AMR) techniques and discuss the interrelationship between AMR and the Nth-order advection schemes.

Cosler, D.; Ibaraki, M.

2004-12-01

351

The Mass of Systems at 2.5 < z < 5  

NASA Astrophysics Data System (ADS)

We present early results from the One-Degree Deep (ODD) survey to measure the mass of 2.5 < z < 5 Lyman break galaxies (LBGs) and damped Lyman alpha systems (DLAs) from their spatial correlation functions. The ODD survey utilizes the Subaru Suprime-Cam wide-field imager and the Keck DEIMOS spectrograph and aims to increase the z > 3.5 LBG spectroscopic sample by an order of magnitude. These spectra will provide the much needed insight into the nature of high redshift protogalaxies and their mass evolution. The ODD survey builds upon the results of our narrow-field survey at z ˜ 3 for LBGs associated with DLAs. In that work, we made an independent measurement of the spatial LBG auto-correlation and the first measurement of the spatial DLA-LBG cross-correlation. The ODD survey will greatly improve the statistics of both results and make the first measurements of the spatial correlation functions at z ˜ 4. In addition, we will estimate the average mass of R < 25.5 high redshift QSOs using this technique and study the large scale behavior of 2.5 < z < 5 systems.

Cooke, J.; Wolfe, A. M.; Gawiser, E.; Prochaska, J. X.

2005-12-01

352

An extrasolar planetary system with three Neptune-mass planets.  

PubMed

Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 au (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star. PMID:16710412

Lovis, Christophe; Mayor, Michel; Pepe, Francesco; Alibert, Yann; Benz, Willy; Bouchy, François; Correia, Alexandre C M; Laskar, Jacques; Mordasini, Christoph; Queloz, Didier; Santos, Nuno C; Udry, Stéphane; Bertaux, Jean-Loup; Sivan, Jean-Pierre

2006-05-18

353

An extrasolar planetary system with three Neptune-mass planets  

E-print Network

Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 AU (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star.

C. Lovis; M. Mayor; F. Pepe; Y. Alibert; W. Benz; F. Bouchy; A. C. M. Correia; J. Laskar; C. Mordasini; D. Queloz; N. C. Santos; S. Udry; J. -L. Bertaux; J. -P. Sivan

2007-03-01

354

Tenth Goddard Conference on Mass Storage Systems and Technologies in Cooperation with the Nineteenth IEEE Symposium on Mass Storage Systems  

NASA Technical Reports Server (NTRS)

This document contains copies of those technical papers received in time for publication prior to the Tenth Goddard Conference on Mass Storage Systems and Technologies which is being held in cooperation with the Nineteenth IEEE Symposium on Mass Storage Systems at the University of Maryland University College Inn and Conference Center April 15-18, 2002. As one of an ongoing series, this Conference continues to provide a forum for discussion of issues relevant to the ingest, storage, and management of large volumes of data. The Conference encourages all interested organizations to discuss long-term mass storage requirements and experiences in fielding solutions. Emphasis is on current and future practical solutions addressing issues in data management, storage systems and media, data acquisition, long-term retention of data, and data distribution. This year's discussion topics include architecture, future of current technology, storage networking with emphasis on IP storage, performance, standards, site reports, and vendor solutions. Tutorials will be available on perpendicular magnetic recording, object based storage, storage virtualization and IP storage.

Kobler, Benjamin (Editor); Hariharan, P. C. (Editor)

2002-01-01

355

Cataclysmic Variables  

E-print Network

Cataclysmic variables are binary stars in which a relatively normal star is transferring mass to its compact companion. This interaction gives rise to a rich range of behaviour, of which the most noticeable are the outbursts that give the class its name. Novae belong to the class, as do the less well known dwarf novae and magnetic systems. Novae draw their energy from nuclear reactions, while dwarf novae rely on gravity to power their smaller eruptions. All the different classes of cataclysmic variable can be accommodated within a single framework and this article will describe the framework, review the properties of the main types of system and discuss models of the outbursts and of the long-term evolution.

Robert Connon Smith

2007-01-23

356

Indoor air quality and the variable-air-volume\\/bypass filtration system: Chamber experiment  

Microsoft Academic Search

Two series of experiments were performed in an all aluminum chamber under controlled conditions to investigate whether the variable-air-volume\\/bypass filtration system (VAV\\/BPFS) reduces indoor air pollutant concentrations relative to a conventional variable-air-volume (VAV) system. Twelve short-term experiments (100 min) were performed for each ventilation system using indoor sources and one energy load. Also, twelve long-term experiments (240 min) were performed

M. M. Meckler

1996-01-01

357

Study of Neural Network PID Control in Variable-frequency Air-conditioning System  

Microsoft Academic Search

This paper aims at the control of variable-frequency air-conditioning system that has characteristic as large inertia and pure lag. The neural network PID control in the variable-frequency air-conditioning system is introduced and simulated. In the learning algorithm of neural network PID controller, the output of system is needed to tune the weights of neural network while it is difficult to

Jiangjiang Wang; Chunfa Zhang; Youyin Jing; Dawei An

2007-01-01

358

Conditions on systems of interacting qubits for classical behavior of their macroscopic variables  

SciTech Connect

It is shown that the conditions for classical behavior, in the sense of zero dispersion of all macroscopic variables, for systems of qubits with different dynamics, depend on whether the interaction is local or global. In the case of local interaction, macroscopic coarse-graining is enough. On the other hand, coarse-grained macroscopic variables of globally interacting large systems of qubits have negligible dispersion only if the system is exposed to some form of the environmental decoherence.

Buric, Nikola [Institute of Physics, University of Belgrade, P.O. Box 68, 11000 Belgrade (Serbia)

2009-07-15

359

Power optimization of variable-voltage core-based systems  

Microsoft Academic Search

The growing class of portable systems, such as personal computing and communication devices, has resulted in a new set of system design requirements, mainly characterized by dominant importance of power minimization and design reuse. The energy efficiency of systems-on-a-chip (SOC) could be much improved if one were to vary the supply voltage dynamically at run time. We develop the design

Inki Hong; Darko Kirovski; Gang Qu; Miodrag Potkonjak; Mani B. Srivastava

1999-01-01

360

Design of a ram accelerator mass launch system  

NASA Technical Reports Server (NTRS)

The ram accelerator mass launch system has been proposed to greatly reduce the costs of placing acceleration-insensitive payloads into low earth orbit. The ram accelerator is a chemically propelled, impulsive mass launch system capable of efficiently accelerating relatively large masses from velocities of 0.7 km/sec to 10 km/sec. The principles of propulsion are based on those of a conventional supersonic air-breathing ramjet; however the device operates in a somewhat different manner. The payload carrying vehicle resembles the center-body of the ramjet and accelerates through a stationary tube which acts as the outer cowling. The tube is filled with premixed gaseous fuel and oxidizer mixtures that burn in the vicinity of the vehicle's base, producing a thrust which accelerates the vehicle through the tube. This study examines the requirement for placing a 2000 kg vehicle into a 500 km circular orbit with a minimum amount of on-board rocket propellant for orbital maneuvers. The goal is to achieve a 50 pct payload mass fraction. The proposed design requirements have several self-imposed constraints that define the vehicle and tube configurations. Structural considerations on the vehicle and tube wall dictate an upper acceleration limit of 1000 g's and a tube inside diameter of 1.0 m. In-tube propulsive requirements and vehicle structural constraints result in a vehicle diameter of 0.76 m, a total length of 7.5 m and a nose-cone half angle of 7 degrees. An ablating nose-cone constructed from carbon-carbon composite serves as the thermal protection mechanism for atmospheric transit.

Aarnio, Michael; Armerding, Calvin; Berschauer, Andrew; Christofferson, Erik; Clement, Paul; Gohd, Robin; Neely, Bret; Reed, David; Rodriguez, Carlos; Swanstrom, Fredrick

1988-01-01

361

Fuzzy logic based intelligent control of a variable speed cage machine wind generation system  

Microsoft Academic Search

The paper describes a variable speed wind generation system where fuzzy logic principles are used for efficiency optimization and performance enhancement control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which pumps power to a utility grid or can supply to an autonomous system. The generation system has fuzzy logic control with

M. G. Simoes; B. K. Bose; R. J. Spiegel

1997-01-01

362

Fault Tolerant Control for Takagi-Sugeno systems with unmeasurable premise variables by trajectory tracking  

E-print Network

Fault Tolerant Control for Takagi-Sugeno systems with unmeasurable premise variables by trajectory for fault tolerant control of nonlinear systems described by Takagi- Sugeno fuzzy systems with unmeasurable the knowledge of the system states and of the occurring faults. These signals are estimated from a Proportional

Paris-Sud XI, Université de

363

Design and application of fuzzy control system of engine variable valve timing  

Microsoft Academic Search

In this paper, a design method of fuzzy control system of engine variable valve timing (VVT) is proposed. In this system, the fuzzy controller is used. The VVT system adopted fuzzy controller eliminates shortcomings in traditional control method such as low accuracy and unsteadiness etc. It has been proved by vehicle road test that the system is effective to meet

Chang Wenxiu; Li Liguang; Tao Jianwu; Xiao Min; Zeng Zhaoyang

1999-01-01

364

Errors-in-Variables identification in bilaterally coupled systems with application  

E-print Network

to sensor noise a closed-loop errors-in-variables problem results, for which an attractive non be described in the form of two-port systems or bilaterally coupled systems. Exchange of energy between e.g. also port-Hamiltonian systems. Bilat- eral coupling of systems is also a general tool

Van den Hof, Paul

365

Mass spectrometric identification, sequence evolution, and intraspecific variability of dimeric peptides encoded by cockroach akh genes.  

PubMed

Neuropeptides are structurally the most diverse group of messenger molecules of the nervous system. Regarding neuropeptide identification, distribution, function, and evolution, insects are among the best studied invertebrates. Indeed, more than 100 neuropeptides are known from single species. Most of these peptides can easily be identified by direct tissue or cell profiling using MALDI-TOF MS. In these experiments, protein hormones with extensive post-translational modifications such as inter- and intramolecular disulfides are usually missed. It is evident that an exclusion of these bioactive molecules hinders the utilization of direct profiling methods in comprehensive peptidomic analyses. In the current study, we focus on the detection and structural elucidation of homo- and heterodimeric adipokinetic hormone precursor-related peptides (APRPs) of cockroaches. The physiological relevance of these molecules with highly conserved sequences in insects is still uncertain. Sequence similarities with vertebrate growth hormone-releasing factors have been reported, but remarkably, few data regarding APRP processing exist and these data are restricted to locusts. Here, we elucidated sequences of carbamidomethylated APRP monomers of different cockroaches by means of MALDI-TOF MS(2), and we were able to identify a surprisingly large number of APRP sequences, resulting either from intraspecific amino acid substitutions within the APRP sequences or C-terminal truncated APRPs. PMID:25524231

Sturm, Sebastian; Predel, Reinhard

2015-02-01

366

Sliding mode variable structure control for parameter uncertain stochastic systems with time-varying delay  

Microsoft Academic Search

In this paper, the variable structure control problem for a class uncertain of stochastic system with time-varying delay is investigated. Firstly, a new concept of the subordinated reachability of the sliding motion is introduced to approach approximately the specified sliding surface. The variable structure control law is then proposed to ensure that the sliding motion is subordinated reachable. Furthermore, a

Hailong Xing; C. C. Gao; Donghai Li

2009-01-01

367

Assessment of spatial and temporal soil moisture variability using Geographic Information System techniques  

Microsoft Academic Search

The objectives of this study were (1) to evaluate soil moisture variability under different land cover conditions and (2) to explore the effectiveness of geographic information system (GIS) technology in assessing the spatial and temporal soil moisture variability. The research was conducted on four 60 by 50 meter plots located on bare smooth soil, bare rough soil, mixed vegetation, and

Ahmed Fahsi; Teferi D. Tsegaye; Tommy L. Coleman; A. Manu; Z. Senwo

1997-01-01

368

Language as a complex system: the case of phonetic variability Philippe Blache & Christine Meunier  

E-print Network

Language as a complex system: the case of phonetic variability Philippe Blache & Christine Meunier. In this perspective, each linguistic domain, such as phonetics, phonology, syntax, pragmatics, etc., is described a unique domain. We illustrate this problem with the case of phonetic variability and show how different

Paris-Sud XI, Université de

369

Continuously variable transmission hydraulic control system having two pressure regulating valves  

Microsoft Academic Search

A hydraulic control system is described for a continuously variable transmission having first and second variable-diameter pulleys provided on a first and a second shafts, a transmission belt connecting the first and second pulleys to transmit power from one of the first and second pulleys to the other, and a pair of hydraulic cylinders for changing an effective diameter of

D. Sawada; M. Sugaya; Y. Soga; R. Imai

1987-01-01

370

A high pressure modulated molecular beam mass spectrometric sampling system  

NASA Technical Reports Server (NTRS)

The current state of understanding of free-jet high pressure sampling is critically reviewed and modifications of certain theoretical and empirical considerations are presented. A high pressure, free-jet expansion, modulated molecular beam, mass spectrometric sampling apparatus was constructed and this apparatus is described in detail. Experimental studies have demonstrated that the apparatus can be used to sample high temperature systems at pressures up to one atmosphere. Condensible high temperature gaseous species have been routinely sampled and the mass spectrometric detector has provided direct identification of sampled species. System sensitivity is better than one tenth of a part per million. Experimental results obtained with argon and nitrogen beams are presented and compared to theoretical predictions. These results and the respective comparison are taken to indicate acceptable performance of the sampling apparatus. Results are also given for two groups of experiments related to hot corrosion studies. The formation of gaseous sodium sulfate in doped methane-oxygen flames was characterized and the oxidative vaporization of metals was studied in an atmospheric pressure flowing gas system to which gaseous salt partial pressures were added.

Stearns, C. A.; Kohl, F. J.; Fryburg, G. C.; Miller, R. A.

1977-01-01

371

Grand challenges in mass storage: A systems integrators perspective  

NASA Technical Reports Server (NTRS)

Within today's much ballyhooed supercomputing environment, with its CFLOPS of CPU power, and Gigabit networks, there exists a major roadblock to computing success; that of Mass Storage. The solution to this mass storage problem is considered to be one of the 'Grand Challenges' facing the computer industry today, as well as long into the future. It has become obvious to us, as well as many others in the industry, that there is no clear single solution in sight. The Systems Integrator today is faced with a myriad of quandaries in approaching this challenge. He must first be innovative in approach, second choose hardware solutions that are volumetric efficient; high in signal bandwidth; available from multiple sources; competitively priced, and have forward growth extendibility. In addition he must also comply with a variety of mandated, and often conflicting software standards (GOSIP, POSIX, IEEE, MSRM 4.0, and others), and finally he must deliver a systems solution with the 'most bang for the buck' in terms of cost vs. performance factors. These quandaries challenge the Systems Integrator to 'push the envelope' in terms of his or her ingenuity and innovation on an almost daily basis. This dynamic is explored further, and an attempt to acquaint the audience with rational approaches to this 'Grand Challenge' is made.

Lee, Richard R.; Mintz, Daniel G.

1993-01-01

372

Structure of variability of Alboran Sea frontal system  

SciTech Connect

Physical characteristics of the Alboran Sea in the western Mediterranean were examined in October 1977 during a survey by ship and aircraft. The main features observed were a distinct oceanic front coinciding with the jet of incoming North Atlantic water and an associated anticyclonic gyre in the western half of the basin. The front was confined to the upper 200 m and was a continuous feature extending from the Strait of Gibraltar 500 km eastward to the prime meridian. Of particular interest was the observed variability of the anticyclonic gyre. In 10 days between two surveys the center of the gyre shifted 50 km westward. This shift may correspond to changes in strength of the North Atlantic inflow as inferred by local wind and the average atmospheric pressure over the western Mediterranean.

Cheney, R.E.; Doblar, R.A.

1982-01-20

373

Control System Upgrade for a Mass Property Measurement Facility  

NASA Technical Reports Server (NTRS)

The Mass Property Measurement Facility (MPMF) at the Goddard Space Flight Center has undergone modifications to ensure the safety of Flight Payloads and the measurement facility. The MPMF has been technically updated to improve reliability and increase the accuracy of the measurements. Modifications include the replacement of outdated electronics with a computer based software control system, the addition of a secondary gas supply in case of a catastrophic failure to the gas supply and a motor controlled emergency stopping feature instead of a hard stop.

Chambers, William; Hinkle, R. Kenneth (Technical Monitor)

2002-01-01

374

Binary System with Components of Different Masses in the Linear Regime of the Characteristic Formulation of General Relativity  

E-print Network

A study of binary systems composed of two point particles with different masses in the linear regime of the characteristic formulation of general relativity is provided. The boundary conditions at the world tubes generated by the particle's orbits are explored, when the metric variables are decomposed in spin-weighted spherical harmonics. The power lost by the emission of gravitational waves is computed using the News Bondi's functions, and the contribution to the gravitational radiation of several multipole terms is shown.

M., C E Cedeño

2015-01-01

375

Dynamics of a Hard Disk Drive Spindle System Due to Its Structural Design Variables and the Design Variables of Fluid Dynamic Bearings  

Microsoft Academic Search

This research investigates the effect of the groove depth, a design variable of fluid dynamic bearings (FDBs), and the shaft diameter, a structural design variable of a hard disk drive (HDD) on the dynamics of a HDD spindle system. The flying height of the HDD spindle system is determined by using the static analysis of the FDBs. The stiffness and

K. Y. Park; G. H. Jang

2009-01-01

376

Active variable buoyancy control system for MBARI's ROV  

Microsoft Academic Search

The Monterey Bay Aquarium Research Institute (MBARI), with QUEST Integrated Inc., has designed and developed an active buoyancy control system for assisting in the operational control of MBARI's new remotely operated vehicle (ROV) Tiburon. This system is intended to assist in payload, ascent\\/descent and station keeping applications during scientific operations down to a maximum depth of 4000 meters

W. J. Kirkwood; D. E. Steele

1994-01-01

377

Temporal Yield Variability under Conventional and Alternative Management Systems  

Microsoft Academic Search

Year to year variation in yield is an inherent risk associated with crop production and many growers rely on intensive mechanical or chemical inputs to preserve crop yield in the face of fluctuating envi- ronmental conditions. However, as interest grows in alternative crop management systems which depend less on external inputs, determin- ing the degree to which management systems can

Richard G. Smith; Fabian D. Menalled; G. P. Robertson

2007-01-01

378

Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers  

Technology Transfer Automated Retrieval System (TEKTRAN)

Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small...

379

Impact of the Variable Refrigerant Volume Air Conditioning System on Building Energy Efficiency  

E-print Network

The application of the variable refrigerant volume multi-zone air conditioning systems has met with mixed results since the publication of the Design Standard for Energy Efficiency of Public Buildings. This paper analyzes the characteristics...

Zhu, H.

2006-01-01

380

Improving Control of a Dual-Duct Single-Fan Variable Air Volume Systems  

E-print Network

This paper discusses improved control strategies for dual-duct single-fan variable air volume (VAV) systems. Common control strategy for supply air volume modulation is evaluated, and an improved air volume control strategy that maintains separate...

Wei, G.; Martinez, J.; Minihan, T.; Brundidge, T.; Claridge, D. E.; Turner, W. D.

2003-01-01

381

Energy-Saving Design for Pressure Difference Control in Variable Flow Air Conditioning Systems  

E-print Network

This paper analyzes energy-saving design for pressure-difference control in a variable flow air conditioning system, including the application of a pressure-difference control valve and the installation position of a pressure-difference transducer...

Chen, Y.; Zhang, Z.

2006-01-01

382

Method and system to estimate variables in an integrated gasification combined cycle (IGCC) plant  

SciTech Connect

System and method to estimate variables in an integrated gasification combined cycle (IGCC) plant are provided. The system includes a sensor suite to measure respective plant input and output variables. An extended Kalman filter (EKF) receives sensed plant input variables and includes a dynamic model to generate a plurality of plant state estimates and a covariance matrix for the state estimates. A preemptive-constraining processor is configured to preemptively constrain the state estimates and covariance matrix to be free of constraint violations. A measurement-correction processor may be configured to correct constrained state estimates and a constrained covariance matrix based on processing of sensed plant output variables. The measurement-correction processor is coupled to update the dynamic model with corrected state estimates and a corrected covariance matrix. The updated dynamic model may be configured to estimate values for at least one plant variable not originally sensed by the sensor suite.

Kumar, Aditya; Shi, Ruijie; Dokucu, Mustafa

2013-09-17

383

Long-Term Quadrature Light Variability in Early Type Interacting Binary Systems  

NASA Astrophysics Data System (ADS)

Four years of Kepler observations have revealed a phenomenon in the light curves of short-period Algol-type eclipsing binaries that has never been reported from ground-based photometry. These systems display unequal brightness at their quadrature phases that numerically reverses over a time scale of about 100-400 days. We call these systems L/T (leading hemisphere/ trailing hemisphere) variables. Twenty-one such systems have so far been identified in the Kepler database and at least three classes of L/T behavior have been identified. The prototype is WX Draconis (A8V + K0IV, P=1.80 d) which shows L/ T light variations of 2-3%. The primary is a delta Scuti star with a dominant pulsation period of 41 m. The Kepler light curves are being analyzed with the 2013 version of the Wilson-Devinney (WD) program that includes major improvements in modeling star spots (i.e. spot motions due to drift and stellar rotation and spot growth and decay). Preliminary analysis of the WX Dra data suggests that the L/T variability can be fit with either an accretion hot spot on the primary (T = 2.3 T_phot) that jumps in longitude or a magnetic cool spotted region on the secondary. If the latter model is correct the dark region must occupy at least 20% of the surface of the facing hemisphere of the secondary if it is completely black, or a larger area if not completely black. In both hot and cool spot scenarios magnetic fields must play a role in the activity. Echelle spectra were recently secured with the KPNO 4-m telescope to determine the mass ratios of the L/T systems and their spectral types. This information will allow us to assess whether the hot or cool spot model explains the L/T activity. Progress toward this goal will be presented. Support from NASA grants NNX11AC78G and NNX12AE44G and USC’s Women in Science and Engineering (WiSE) program is greatly appreciated.

Peters, Geraldine J.; Wilson, R. E.; Vaccaro, T. R.

2014-01-01

384

Static and Dynamic Variable Voltage Scheduling Algorithms for Real-Time Heterogeneous Distributed Embedded Systems  

Microsoft Academic Search

This paper addresses the problem of static and dynamic variable voltage scheduling of multi-rate periodic task graphs (i.e., tasks with precedence relationships) and aperiodic tasks in heterogeneous distributed real-time embedded systems. Such an embedded system may contain general-purpose processors, field-programmable gate arrays (FPGAs) and application-specific integrated circuits (ASICs). Variable voltage scheduling is performed only on general-purpose processors. The static scheduling

Jiong Luo; Niraj K. Jha

2002-01-01

385

Design of a Ram Accelerator mass launch system  

NASA Technical Reports Server (NTRS)

The Ram Accelerator, a chemically propelled, impulsive mass launch system, is presented as a viable concept for directly launching acceleration-insensitive payloads into low Earth orbit. The principles of propulsion are based on those of an airbreathing supersonic ramjet. The payload vehicle acts as the ramjet centerbody and travels through a fixed launch tube that acts as the ramjet outer cowling. The launch tube is filled with premixed gaseous fuel and oxidizer mixtures that combust at the base of the vehicle and produce thrust. Two modes of in-tube propulsion involving ramjet cycles are used in sequence to accelerate the vehicle from 0.7 km/sec to 9 km/sec. Requirements for placing a 2000 kg vehicle into a 500-km circular orbit, with a minimum amount of onboard rocket propellant for orbital maneuvers, are examined. It is shown that in-tube propulsion requirements dictate a launch tube length of 5.1 km to achieve an exit velocity of 9 km/sec, with peak accelerations not to exceed 1000 g's. Aerodynamic heating due to atmospheric transit requires minimal ablative protection and the vehicle retains a large percentage of its exit velocity. An indirect orbital insertion maneuver with aerobraking and two apogee burns is examined to minimize the required onboard propellant mass. An appropriate onboard propulsion system design to perform the required orbital maneuvers with minimum mass requirements is also determined. The structural designs of both the launch tube and the payload vehicle are examined using simple structural and finite element analysis for various materials.

1988-01-01

386

Seasonal variability of water mass distribution in the southeastern Beaufort Sea determined by total alkalinity and ?18O  

NASA Astrophysics Data System (ADS)

We examined the seasonal variability of water mass distributions in the southeastern Beaufort Sea from data collected between September 2003 and August 2004. Salinity, total alkalinity (TA) and isotopic composition (?18O) of seawater were used together as tracers of freshwater input, i.e., meteoric water and sea ice meltwater. We used an optimum multiparameter analysis to identify the different water masses, including the Mackenzie River, sea ice melt (SIM), winter polar mixed layer (PML), upper halocline water (UHW) with core salinity of 33.1 psu (Pacific origin) and Atlantic Water. Computed values of CO2 fugacity in seawater (fCO2-sw) show that the surface mixed layer (SML) remains mostly undersaturated (328 ± 55?atm, n = 552) with respect to the average atmospheric CO2 concentration (380 ± 5 ?atm) over the study period. The influence of the Mackenzie River (fCO2-SW > 500 ?atm) was relatively small in the southeastern Beaufort Sea, and significant fractions were only observed on the inner Mackenzie Shelf. The contribution of sea ice melt (fCO2-SW < 300 ?atm) to the SML could reach 30% beyond the shelf break and close to the ice pack in autumn. The density of the PML increased through the winter due to cooling and brine rejection. The winter PML reached a maximum depth of 70 m in late April. The UHW (fCO2-SW > 600 ?atm) was usually located between 120 and 180 m depth, but could contribute to the SML during wind-driven upwelling events, in summer and autumn, and during brine-driven eddies, in winter.

Lansard, Bruno; Mucci, Alfonso; Miller, Lisa A.; MacDonald, Robie W.; Gratton, Yves

2012-03-01

387

Experience with the UniTree mass storage system  

SciTech Connect

Lawrence Berkeley Laboratory (LBL) is a beta test site for the UniTree mass storage system. Our initial configuration is based on a Sun workstation and includes 10 gigabytes (GB) of magnetic disk cache, 700 GB of Exabyte 8 mm tape storage, with two tape robots. We support a user community of 15 to 20 active users, about 250,000 files, and 33 GB of user data. The largest file stored is 1.5 GB. As of May 1992, we consider the system to be adequately stable and reliable for production use. As a beta site, we have worked on the Sun port, on the tape drivers for SunOS, and on integrating our tape robots into the UniTree software. File retrieval from tape usually takes less than five minutes. Continuing concerns are tape longevity and reliability, and improving performance to support 100 Mb FDDI.

Holmes, H.H.; Loken, S.

1992-09-01

388

The mass flux of micrometeoroids into the Saturnian system  

NASA Astrophysics Data System (ADS)

There is an ongoing debate about the age of Saturn's rings being: a) rather young, or b) formed contemporaneously with the planet and its satellites. The waterice rings contain about 5% of rocky material, originating from the continuous bombardment of the rings by interplanetary micrometeoroids. Knowledge of the incoming mass flux would allow to estimate the ring's exposure time. Model calculations suggest exposure times of 108 years, implying a late ring formation. This scenario is problematic because, for example, the tidal disruption of a Mimas-sized moon or of a comet within the planet's Roche zone would lead to a much larger rock content than observed today. Here we report on the first direct measurement of the meteoroid flux into the Saturnian system by Cassini's Cosmic Dust Analyzer (CDA).We measured the impact velocity vectors of about 140 extrinsic micrometeoroids with radii ? 2?m, and determined their orbital elements. On the basis of these measurements we determined the mass flux into the Saturnian system. Our findings suggest a ring exposure time of 4.5 billion years and is in support of an early ring formation scenario.

Kempf, S.; Altobelli, N.; Horanyi, M.; Srama, R.

2014-04-01

389

Systems for 42 V mass-market automobiles  

NASA Astrophysics Data System (ADS)

With the introduction of the Toyota Crown Royal Saloon in August, 2001, 42 V automotive electrical systems made the transition from a technology for the future to present-day production. Nevertheless, there is widespread malaise in the 42 V technical community, stemming from a slower than expected introduction to the marketplace. This paper discusses some of the reasons for the slow adoption of this technology, and indicates a possible way forward. This paper looks beyond the initial uses of 42 V in limited-volume, high-end cars and light trucks, and discusses the prospects for 42 V in mass-market vehicles, given what is presently known about the technology. It is concluded that a case can be made for 42 V, even at some increment in cost. The motivation is improved fuel economy. The cost targets necessary for this benefit to be achieved are discussed, and new components being widely discussed as part of future electrical systems are evaluated for mass-market applications. New developments with higher potential are suggested.

Keim, Thomas A.

390

Orbit Approach to Separation of Variables in (3)-Related Integrable Systems  

NASA Astrophysics Data System (ADS)

Using the orbit method we reveal geometric and algebraic meaning of separation of variables for integrable systems on coadjoint orbits of an (3) loop algebra. We consider two types of generic orbits, embedded into a common manifold endowed with two nonsingular Lie-Poisson brackets. We prove that separation of variables on orbits of both types is realized by the same variables of separation. We also construct integrable systems on the orbits: a coupled 3-component nonlinear Schrödinger equation and an isotropic SU(3) Landau-Lifshitz equation.

Bernatska, Julia; Holod, Petro

2015-01-01

391

Orbit Approach to Separation of Variables in sl(3)-Related Integrable Systems  

E-print Network

Using the orbit method we attempt to reveal geometric and algebraic meaning of separation of variables for the integrable systems on coadjoint orbits in an $\\mathfrak{sl}(3)$ loop algebra. We consider two types of generic orbits embedded into a common manifold, endowed with two nonsingular Lie-Poisson brackets. We prove that separation of variables on orbits of both types is realized by the same variables of separation. We also construct the integrable systems on these orbits: a coupled 3-component nonlinear Schr\\"{o}dinger equation and an isotropic SU(3) Landau-Lifshitz equation.

Julia Bernatska; Petro Holod

2014-08-16

392

Orbit Approach to Separation of Variables in sl(4)-Related Integrable Systems  

E-print Network

Separation of variables by means of the orbit method is implemented to integrable systems on coadjoint orbits in an $\\mathfrak{sl}(4)$ loop algebra. This is a development and a kind of explanation for Sklyanin's procedure of separation of variables. It is shown that points on a spectral curve serve as variables of separation for two integrable systems living on two generic orbits embedded into a common manifold. These orbits are endowed with different nonsingular Lie-Poisson brackets. Explicit expressions for the case of $\\mathfrak{sl}(4)$ loop algebra are given.

Julia Bernatska

2014-08-16

393

Variability of African Farming Systems from Phenological Analysis of NDVI Time Series  

NASA Technical Reports Server (NTRS)

Food security exists when people have access to sufficient, safe and nutritious food at all times to meet their dietary needs. The natural resource base is one of the many factors affecting food security. Its variability and decline creates problems for local food production. In this study we characterize for sub-Saharan Africa vegetation phenology and assess variability and trends of phenological indicators based on NDVI time series from 1982 to 2006. We focus on cumulated NDVI over the season (cumNDVI) which is a proxy for net primary productivity. Results are aggregated at the level of major farming systems, while determining also spatial variability within farming systems. High temporal variability of cumNDVI occurs in semiarid and subhumid regions. The results show a large area of positive cumNDVI trends between Senegal and South Sudan. These correspond to positive CRU rainfall trends found and relate to recovery after the 1980's droughts. We find significant negative cumNDVI trends near the south-coast of West Africa (Guinea coast) and in Tanzania. For each farming system, causes of change and variability are discussed based on available literature (Appendix A). Although food security comprises more than the local natural resource base, our results can perform an input for food security analysis by identifying zones of high variability or downward trends. Farming systems are found to be a useful level of analysis. Diversity and trends found within farming system boundaries underline that farming systems are dynamic.

Vrieling, Anton; deBeurs, K. M.; Brown, Molly E.

2011-01-01

394

On Power Quality of Variable-Speed Constant-Frequency Aircraft Electric Power Systems  

Microsoft Academic Search

In this paper, a comprehensive model of the variable-speed constant-frequency aircraft electric power system is developed to study the performance characteristics of the system and, in particular, the system power quality over a frequency range of operation of 400 Hz to 800 Hz. A fully controlled active power filter is designed to regulate the load terminal voltage, eliminate harmonics, correct

Ahmad Eid; Hassan El-Kishky; Mazen Abdel-Salam; Mohamed T. El-Mohandes

2010-01-01

395

Automatic Optimisation of Parallel Linear Algebra Routines in Systems with Variable Load*  

E-print Network

Automatic Optimisation of Parallel Linear Algebra Routines in Systems with Variable Load* Javier. In this work an architecture of an automatically tuned linear algebra li- brary proposed in previous works the installation process in a system, the linear algebra routines will be tuned automatically to the system condi

Dongarra, Jack

396

Dynamic Modeling of Hydraulic Power Steering System with Variable Ratio Rack and Pinion Gear  

Microsoft Academic Search

A comprehensive mathematical model of a typical hydraulic power steering system equipped with variable ratio rack and pinion gear is developed. The steering system's dynamic characteristics are investigated and its forced vibrations are compared with those obtained from a counterpart system with a constant ratio rack and pinion gear. The modeling details of the mechanism subsystem, hydraulic supply lines subsystem

Nong Zhang; Miao Wang

2005-01-01

397

Controlling Chaos of Hybrid Systems by Variable Threshold Values  

NASA Astrophysics Data System (ADS)

We try to stabilize unstable periodic orbits embedded in a given chaotic hybrid dynamical system by a perturbation of a threshold value. In conventional chaos control methods, a control input is designed by state-feedback, which is proportional to the difference between the target orbit and the current state, and it is applied to a specific system parameter or the state as a small perturbation. During a transition state, the control system consumes a certain control energy given by the integration of such perturbations. In our method, we change the threshold value dynamically to control the chaotic orbit. Unlike the OGY method and the delayed feedback control, no actual control input is added into the system. The state-feedback is utilized only to determine the dynamic threshold value, thus the orbit starting from the current threshold value reaches the next controlled threshold value without any control energy. We obtain the variation of the threshold value from the composite Poincaré map, and the controller is designed by the linear feedback theory with this variation. We demonstrate this method in simple hybrid chaotic systems and show its control performances by evaluating basins of attraction.

Ito, Daisuke; Ueta, Tetsushi; Kousaka, Takuji; Imura, Jun'ichi; Aihara, Kazuyuki

398

Design of variable frequency endoscope ultrasonic digital imaging system  

NASA Astrophysics Data System (ADS)

This paper presented a real-time endoscope ultrasonic digital imaging system, which was based on FPGA and applied for gastrointestinal examination. Four modules, scan-line data processing module, coordinate transformation and interpolation algorithm module, cache reading and writing control module and transmitting and receiving control module were included in this FPGA based system. Through adopting different frequency ultrasound probes in a single insertion of endoscope, the system showed a high speed data processing mechanism capable of achieving images with various display effects. A high-precision modified coordinate calibration CORDIC (HMCC-CORDIC) algorithm was employed to realize coordinate transformation and interpolation simultaneously, while the precision and reliability of the algorithm could be greatly improved through utilizing the pipeline structure based on temporal logic. Also, system real-time control by computer could be achieved through operating under the condition of USB2.0 interface. The corresponding experimental validations proved the feasibility and the correctness of the proper data processing mechanism, the HMCC-CORDIC algorithm and the USB real-time control. Finally, the specific experimental sample, a tissue mimicking phantom, was imaged in real-time (25 frames per second) by an endoscope ultrasonic imaging system with image size 1024×1024. The requirements for clinical examination could be well satisfied with the imaging parameters discussed above.

Li, Ya-nan; Bai, Bao-ping; Chen, Xiao-dong; Zhao, Qiang; Deng, Hao-ran; Wang, Yi; Yu, Dao-yin

2013-12-01

399

Time Evolution of the Dynamical Variables of a Stochastic System.  

ERIC Educational Resources Information Center

By using the method of moments, it is shown that several important and apparently unrelated theorems describing average properties of stochastic systems are in fact particular cases of a general law; this method is applied to generalize the virial theorem and the fluctuation-dissipation theorem to the time-dependent case. (Author/SK)

de la Pena, L.

1980-01-01

400

2D and 3D Mass Transfer Simulations in ? Lyrae System  

NASA Astrophysics Data System (ADS)

2D and 3D mass transfer simulations of the mass transfer in ? Lyrae binary system. We have received that from a point L3 40 per cent of mass transfer from L1-point is lost.The structure of a gas envelope, around system is calculated.3-D mass transfer simulations has shown presence the spiral shock in the disk around primary star's and a jet-like structures (a mass flow in vertical direction) over a stream.

Nazarenko, V. V.; Glazunova, L. V.; Karetnikov, V. G.

2001-12-01

401

A computational method to extract macroscopic variables and their dynamics in multiscale systems  

E-print Network

This paper introduces coordinate-independent methods for analysing multiscale dynamical systems using numerical techniques based on the transfer operator and its adjoint. In particular, we present a method for testing whether an arbitrary dynamical system exhibits multiscale behaviour and for estimating the time-scale separation. For systems with such behaviour, we establish techniques for analysing the fast dynamics in isolation, extracting slow variables for the system, and accurately simulating these slow variables at a large time step. We illustrate our method with numerical examples and show how the reduced slow dynamics faithfully represents statistical features of the full dynamics which are not coordinate dependent.

Gary Froyland; Georg A. Gottwald; Andy Hammerlindl

2014-09-29

402

Volcanic Gas Emissions Mapping Using a Mass Spectrometer System  

NASA Technical Reports Server (NTRS)

The visualization of hazardous gaseous emissions at volcanoes using in-situ mass spectrometry (MS) is a key step towards a better comprehension of the geophysical phenomena surrounding eruptive activity. In-Situ gas data consisting of helium, carbon dioxide, sulfur dioxide, and other gas species, were acquired with an MS system. MS and global position system (GPS) data were plotted on ground imagery, topography, and remote sensing data collected by a host of instruments during the second Costa Rica Airborne Research and Technology Applications (CARTA) mission This combination of gas and imaging data allowed 3-dimensional (3-D) visualization of the volcanic plume end the mapping of gas concentration at several volcanic structures and urban areas This combined set of data has demonstrated a better tool to assess hazardous conditions by visualizing and modeling of possible scenarios of volcanic activity. The MS system is used for in-situ measurement of three-dimensional gas concentrations at different volcanic locations with three different transportation platforms, aircraft, auto, and hand carried. The demonstration for urban contamination mapping is also presented as another possible use for the MS system.

Griffin, Timothy P.; Diaz, J. Andres

2008-01-01

403

Internal combustion engine air intake system with variable effective length  

SciTech Connect

An air intake system for feeding intake air to combustion chambers of a multicylinder internal combustion engine having two groups of longitudinally spaced engine cylinders is described comprising: a. a longitudinally extending surge tank positioned adjacent the engine cylinders; b. flow control valve means for opening and closing the aperture, the flow control valve means including a butterfly valve pivotally mounted in the aperture of the wall extension of the extension portion; and c. actuator means responsive to engine operating conditions for controlling opening and closing of the butterfly valve to vary the extent of flow communication between the volumetric chambers through the aperture, thereby varying the effective length of the intake system with engine operating conditions.

Wada, H.; Horio, K.; Abe, K.

1988-04-19

404

Self-Calibrating, Variable-Flow Pumping System  

NASA Technical Reports Server (NTRS)

Pumping system provides accurate, controlled flows of two chemical liquids mixed in spray head and react to form rigid or flexible polyurethane or polyisocyanurate foam. Compatible with currently used polyurethane-based coating materials and gas-bubble-forming agents (called "blowing agents" in industry) and expected to be compatible with materials that used in near future. Handles environmentally acceptable substitutes for chlorofluorocarbon foaming agents.

Walls, Joe T.

1994-01-01

405

Transient Magnetohydrodynamic Free Convective Heat and Mass Transfer Flow with Thermophoresis past a Radiate Inclined Permeable Plate in the Presence of Variable Chemical Reaction and Temperature Dependent Viscosity  

Microsoft Academic Search

In the present study, an analysis is carried out to investiga te the effects of variable chemical reaction, thermophoresis, temperature-dependent viscosity and thermal radiation on an unsteady MHD free convective heat and mass transfer flow of a viscous, incompressible, electrically conducting fluid past an impu lsively started infinite inclined porous plate. The governing nonlinear partial differentia l equations are transformed

M. S. Alam; M. M. Rahman; M. A. Sattar

406

THE INFLUENCE OF VARIABLE ELIMINATION RATE AND BODY FAT MASS IN A PBPK MODEL FOR TCDD IN PREDICTING THE SERUM TCDD CONCENTRATIONS FROM VETERANS OF OPERATION RANCH HAND  

EPA Science Inventory

The Influence of Variable Elimination Rate and Body Fat Mass in a PBPK Model for TCDD in Predicting the Serum TCDD Concentrations from Veterans of Operation Ranch Hand. C Emond1,2, LS Birnbaum2, JE Michalek3, MJ DeVito2 1 National Research Council, National Academy of Scien...

407

Peripheral variability and central constancy in mammalian visual system evolution  

PubMed Central

Neural systems are necessarily the adaptive products of natural selection, but a neural system, dedicated to any particular function in a complex brain, may be composed of components that covary with functionally unrelated systems, owing to constraints beyond immediate functional requirements. Some studies support a modular or mosaic organization of the brain, whereas others emphasize coordination and covariation. To contrast these views, we have analysed the retina, striate cortex (V1) and extrastriate cortex (V2, V3, MT, etc.) in 30 mammals, examining the area of the neocortex and individual neocortical areas and the relative numbers of rods and cones. Controlling for brain size and species relatedness, the sizes of visual cortical areas (striate, extrastriate) within the brains of nocturnal and diurnal mammals are not statistically different from one another. The relative sizes of all cortical areas, visual, somatosensory and auditory, are best predicted by the total size of the neocortex. In the sensory periphery, the retina is clearly specialized for niche. New data on rod and cone numbers in various New World primates confirm that rod and cone complements of the retina vary substantially between nocturnal and diurnal species. Although peripheral specializations or receptor surfaces may be highly susceptible to niche-specific selection pressures, the areal divisions of the cerebral cortex are considerably more conservative. PMID:15875575

Kaskan, Peter M.; Franco, Edna Cristina S.; Yamada, Elizabeth S.; de Lima Silveira, Luiz Carlos; Darlington, Richard B.; Finlay, Barbara L.

2005-01-01

408

Optical mass memory system (AMM-13). AMM-13 system segment specification  

NASA Technical Reports Server (NTRS)

The performance, design, development, and test requirements for an optical mass data storage and retrieval system prototype (AMM-13) are established. This system interfaces to other system segments of the NASA End-to-End Data System via the Data Base Management System segment and is designed to have a storage capacity of 10 to the 13th power bits (10 to the 12th power bits on line). The major functions of the system include control, input and output, recording of ingested data, fiche processing/replication and storage and retrieval.

Bailey, G. A.

1980-01-01

409

Zero and root loci of disturbed spring–mass systems  

PubMed Central

Models consisting of chains of particles that are coupled to their neighbours appear in many applications in physics or engineering, such as in the study of dynamics of mono-atomic and multi-atomic lattices, the resonances of crystals with impurities and the response of damaged bladed discs. Analytical properties of the dynamic responses of such disturbed chains of identical springs and masses are presented, including when damping is present. Several remarkable properties in the location of the resonances (poles) and anti-resonances (zeros) of the displacements in the frequency domain are presented and proved. In particular, it is shown that there exists an elliptical region in the frequency–disturbance magnitude plane from which zeros are excluded and the discrete values of the frequency and disturbance at which double poles occur are identified. A particular focus is on a local disturbance, such as when a spring or damper is modified at or between the first and last masses. It is demonstrated how, notably through normalization, the techniques and results of the paper apply to a broad category of more complex systems in physics, chemistry and engineering. PMID:24711724

Lecomte, Christophe

2014-01-01

410

Super Efimov effect for mass-imbalanced systems  

NASA Astrophysics Data System (ADS)

We study two species of particles in two dimensions interacting by isotropic short-range potentials with the interspecies potential fine-tuned to a p -wave resonance. Their universal low-energy physics can be extracted by analyzing a properly constructed low-energy effective field theory with the renormalization group method. Consequently, a three-body system consisting of two particles of one species and one of the other is shown to exhibit the super Efimov effect, the emergence of an infinite tower of three-body bound states with orbital angular momentum ? =±1 whose binding energies obey a doubly exponential scaling, when the two particles are heavier than the other by a mass ratio greater than 4.034 04 for identical bosons and 2.414 21 for identical fermions. With increasing the mass ratio, the super Efimov spectrum becomes denser which would make its experimental observation easier. We also point out that the Born-Oppenheimer approximation is incapable of reproducing the super Efimov effect, the universal low-energy asymptotic scaling of the spectrum.

Moroz, Sergej; Nishida, Yusuke

2014-12-01

411

Super Efimov effect for mass-imbalanced systems  

E-print Network

We study two species of particles in two dimensions interacting by isotropic short-range potentials with the interspecies potential fine-tuned to a p-wave resonance. Their universal low-energy physics can be extracted by analyzing a properly constructed low-energy effective field theory with the renormalization group method. Consequently, a three-body system consisting of two particles of one species and one of the other is shown to exhibit the super Efimov effect, the emergence of an infinite tower of three-body bound states with orbital angular momentum $l=\\pm1$ whose binding energies obey a doubly exponential scaling, when the two particles are heavier than the other by a mass ratio greater than 4.03404 for identical bosons and 2.41421 for identical fermions. With increasing the mass ratio, the super Efimov spectrum becomes denser which would make its experimental observation easier. We also point out that the Born-Oppenheimer approximation is incapable of reproducing the super Efimov effect, the universal low-energy asymptotic scaling of the spectrum.

Sergej Moroz; Yusuke Nishida

2014-12-24

412

Large-scale variability of wind erosion mass flux rates at Owens Lake 1. Vertical profiles of horizontal mass fluxes of wind-eroded particles with diameter greater than 50 ??m  

USGS Publications Warehouse

A field experiment at Owens (dry) Lake, California, tested whether and how the relative profiles of airborne horizontal mass fluxes for >50-??m wind-eroded particles changed with friction velocity. The horizontal mass flux at almost all measured heights increased proportionally to the cube of friction velocity above an apparent threshold friction velocity for all sediment tested and increased with height except at one coarsesand site where the relative horizontal mass flux profile did not change with friction velocity. Size distributions for long-time-averaged horizontal mass flux samples showed a saltation layer from the surface to a height between 30 and 50 cm, above which suspended particles dominate. Measurements from a large dust source area on a line parallel to the wind showed that even though the saltation flux reached equilibrium ???650 m downwind of the starting point of erosion, weakly suspended particles were still input into the atmosphere 1567 m downwind of the starting point; thus the saltating fraction of the total mass flux decreased after 650 m. The scale length difference and ratio of 70/30 suspended mass flux to saltation mass flux at the farthest downwind sampling site confirm that suspended particles are very important for mass budgets in large source areas and that saltation mass flux can be a variable fraction of total horizontal mass flux for soils with a substantial fraction of <100-??m particles.

Gillette, D.A.; Fryrear, D.W.; Xiao, J.B.; Stockton, P.; Ono, D.; Helm, P.J.; Gill, T.E.; Ley, T.

1997-01-01

413

Time-Variable Phenomena in the Jovian System  

NASA Technical Reports Server (NTRS)

The current state of knowledge of dynamic processes in the Jovian system is assessed and summaries are provided of both theoretical and observational foundations upon which future research might be based. There are three sections: satellite phenomena and rings; magnetospheric phenomena, Io's torus, and aurorae; and atmospheric phenomena. Each chapter discusses time dependent theoretical framework for understanding and interpreting what is observed; others describe the evidence and nature of observed changes or their absence. A few chapters provide historical perspective and attempt to present a comprehensive synthesis of the current state of knowledge.

Belton, Michael J. S. (editor); West, Robert A. (editor); Rahe, Jurgen (editor); Pereyda, Margarita

1989-01-01

414

High temperature VSCF (Variable Speed Constant Frequency) generator system  

NASA Astrophysics Data System (ADS)

The high temperature VSCF generator program was designed to develop a generating system capable of withstanding constantly high oil-in temperatures of 200 C in an ambient environment of 200 C. This is a requirement due to anticipated new fighter aircraft designs that will not be capable of cooling the oil to 100 C as in today's designs due to size restrictions of the heat exchanger and/or extended operation of the aircraft at supersonic speeds. The generator uses composite material to withstand the constant use of 200 C inlet oil.

Maphet, Thomas Allen; McCabria, Jack Lee; Kouba, Carroll Charles; Mitchell, James Thomas; Kwiecinski, James Robert

1989-04-01

415

Angular momentum and disk evolution in very low mass systems  

NASA Astrophysics Data System (ADS)

This review summarises recent observational results regarding the evolution of angular momentum and disks in brown dwarfs. The observations clearly show that brown dwarfs beyond ages of 10 Myr are exclusively fast rotators and do not spin down with age. This suggests that rotational braking by magnetic winds becomes very inefficient or ceases to work in the substellar regime. There is, however, some evidence for braking by disks during the first few Myrs in the evolution, similar to stars. Brown dwarf disks turn out to be scaled down versions of circumstellar disks, with dust settling, grain growth, and in some cases cleared out inner regions. The global disk properties roughly scale with central object mass. The evolutionary timescales in substellar disks are entirely consistent with what is found for stars, which may be challenging to understand. Given these findings, it is likely that brown dwarfs are able to form miniature planetary systems.

Scholz, A.

416

Physics design of fissile mass-flow monitoring system  

SciTech Connect

The system measures the flow rate and uranium-235 content in liquid or gas streams; it does not penetrate the process piping. A moderated fission neutron source is used to periodicially introduce a burst of thermal neutrons into the fluid stream to induce fission; delayed gamma emissions from the resulting fission fragments are detected by high-efficiency scintillators downstream of the neutron source. The fluid flow rate is measure from the time between initiation of the thermal neutron burst and detection of the fission product gamma emissions, and the U-235 content is inferred from the intensity of the gamma burst detected. Design of the fissile mass flow monitor requires satisfaction of several competing constraints. Efficient operation of the monitor requires that source-induced fission rate and detection efficiency be maximized while the source-induced background rate is simultaneoulsy minimized. Near optical nuclear design of the system was achieved using numerous Monte Carlo calculations and measurements. This paper addresses calculational aspects of the physics design for the system applied to UF{sub 6} gas.

Mattingly, J.K.; March-Leuba, J.; Valentine, T.E.; Mihalczo, J.T.; Uckan, T.

1997-09-01

417

Millisecond X-Ray Variability from an Accreting Neutron Star System  

Microsoft Academic Search

We report the detection with the Proportional Counter Array (PCA) on board the Rossi X-Ray Timing Explorer (RXTE) of millisecond variability in the X-ray emission from the low-mass X-ray binary 4U 1728-34. Pulsations at 363 Hz with amplitudes (rms) of 2.5%--10% are present in six of the eight bursts analyzed to date. The strongest were seen in two successive bursts

Tod E. Strohmayer; William Zhang; Jean H. Swank; Alan Smale; Lev Titarchuk; Charles Day; Umin Lee

1996-01-01

418

System for throttling and compensation for variable feedstock properties  

DOEpatents

Apparatus is shown for adjusting the feed rate of pulverized feed material into a pressurized container. The apparatus also has utility for compensating for variations in the permeability of the feed material. A rotor that includes sprues with provision for controlling the pressure distribution along the sprues is located within the pressurized container. The rotor hub is connected to a drive means and a material supply means which extend through the wall of the container. A line for controlling pressure along the sprues by gas injection is connected to a chamber between sections of the sprue for controlling gas pressure at that point. The gas pressure control line is connected to a pressurized gas source and a control system external to the rotor. 10 figs.

Meyer, J. W.

1981-05-05

419

Geochemical and Energetic Variability across Geothermal Systems in Yellowstone National Park (YNP)  

NASA Astrophysics Data System (ADS)

The physical and chemical characteristics of geothermal outflow channels have been evaluated and correlated with microbial community structure within a variety of geothermal springs in Yellowstone National Park (YNP). Several high-temperature (75-90 C), low to near-neutral pH hot springs in YNP were characterized over a two-year period for a comprehensive understanding of the possible geochemical controls on resident chemolithotrophic microbial populations. Our goal was to analyze and compare YNP geothermal systems in terms of the free energy (Grxn) available from various exergonic oxidation/reduction (redox) reactions. Important electron donors in YNP geothermal systems were measured and include H2, H2S , S0, Fe2+, CH4, and NH4+; terminal electron acceptors of noted importance include O2, NO3-, Fe3+, , S0, SO42- and CO2. Thermodynamic modeling of aqueous chemical species was used to calculate the non-standard state free energy values for a variety of oxidation-reduction reactions potentially important for chemolithotrophic metabolism. Energetic profiles as a function of distance from spring source and temperature were calculated for a series of redox reactions in several YNP springs. Variable temperatures and reactant concentrations across several geothermal springs (pH ranges 2.5-6.8) generally did not significantly change the favorability of many of the reactions considered. These findings imply that observable changes in the distribution of microbial populations are likely linked to physical (e.g. mass transfer, temperature) and biological factors. There are, however, important comparisons to be made among exergonic reactions and presumed metabolisms of resident microbial populations. Both energetic and kinetic considerations will be necessary for understanding which oxidation-reduction reactions provide a competitive metabolic advantage to primary producers in geothermal springs.

Ackerman, G. G.; Macur, R. E.; Taylor, W. P.; Kozubal, M. A.; Korf, S.; Inskeep, W. P.

2005-12-01

420

Minimum fuel control of a vehicle with a continuously variable transmission. [control system simulation  

NASA Technical Reports Server (NTRS)

The design and evaluation of a control system for a sedan with a heat engine and a continuously variable transmission, is considered in a effort to minimize fuel consumption and achieve satisfactory dynamic response of vehicle variables as the vehicle is driven over a standard driving cycle. Even though the vehicle system was highly nonlinear, attention was restricted to linear control algorithms which could be easily understood and implemented demonstrated by simulation. Simulation results also revealed that the vehicle could exhibit unexpected dynamic behavior which must be taken into account in any control system design.

Burghart, J. H.; Donoghue, J. F.

1980-01-01

421

Variable cycle stirling engine and gas leakage control system therefor  

SciTech Connect

An improved thermal engine of the type having a displacer body movable between the hot end and the cold end of a chamber for subjecting a fluid within that chamber to a thermodynamic cycle and having a work piston driven by the fluid for deriving a useful work output. The work piston pumps a hydraulic fluid and a hydraulic control valve is connected in line with the hydraulic output conduit such that the flow of hydraulic fluid may be restricted to any desired degree or stopped altogether. The work piston can therefore be controlled by means of a controller device independently from the movement of the displacer such that a variety of engine cycles can be obtained for optimum engine efficiency under varying load conditions. While a Stirling engine cycle is particularly contemplated, other engine cycles may be obtained by controlling the movement of the displacer and work pistons. Also disclosed are a working gas recovery system for controlling leakage of working gas from the displacer chamber, and a compound work piston arrangement for preventing leakage of hydraulic fluid around the work piston into the displacer chamber.

Otters, J.

1984-12-25

422

Characterizing Vertical Mass Flux Profiles in Aeolian Saltation Systems  

E-print Network

This dissertation investigates characteristics of the vertical distributions of mass flux observed in field and laboratory experiments. Thirty vertical mass flux profiles were measured during a field experiment in Jericoacoara, Brazil from October...

Farrell, Eugene

2012-07-16

423

Evaluation of Application Accuracy and Performance of a Hydraulically Operated Variable-Rate Aerial Application System  

Technology Transfer Automated Retrieval System (TEKTRAN)

An aerial variable-rate application system consisting of a DGPS-based guidance system, automatic flow controller, and hydraulically controlled pump/valve was evaluated for response time to rapidly changing flow requirements and accuracy of application. Spray deposition position error was evaluated ...

424

A variable speed wind energy conversion scheme for connection to weak AC systems  

Microsoft Academic Search

A three level control system for a variable speed wind energy conversion scheme (VSWECS) supplying a weak AC power system is presented. The objective of the control strategy is to maximize energy capture and simultaneously to support the voltage of the bus where the VSWECS is connected. Using an insulated gate bipolar transistor (IGBT) inverter, both control of active and

A. S. Neris; N. A. Vovos; G. B. Giannakopoulos

1999-01-01

425

State variable integration in SOA Energy Management System for building air-conditioners  

Microsoft Academic Search

Advancement of Energy Management Systems (EMSs) for building facilities is becoming more important for sustainable development. The Service Oriented Architecture (SOA) will be a powerful approach for these systems. Distributed type building air-conditioners, which are dominant in Japan, have many distributed raw state variables required by an EMS. This makes it difficult to apply the SOA to those EMSs. We

Chuzo Ninagawa; Tomotaka Sato

2010-01-01

426

Designing Reliable Systems from Unreliable Components: The Challenges of Transistor Variability and Degradation  

Microsoft Academic Search

As technology scales, variability in transistor performance continues to increase, making transistors less and less reliable. This creates several challenges in building reliable systems, from the unpredictability of delay to increasing leakage current. Finding solutions to these challenges require a concerted effort on the part of all the players in a system design. This article discusses these effects and proposes

Shekhar Y. Borkar

2005-01-01

427

DFIG-Based Power Generation System With UPS Function for Variable-Speed Applications  

Microsoft Academic Search

The power generation system with a doubly fed induction generator (DFIG), which can be used as an autonomous power system after the loss of mains in a distributed generation network, is described. After the mains outage, a fixed frequency and an amplitude of the output voltage are obtained, despite the variable rotor speed. For this reason, it can be successfully

Grzegorz Iwanski; Wlodzimierz Koczara

2008-01-01

428

A flexible active and reactive power control strategy for a variable speed constant frequency generating system  

Microsoft Academic Search

Variable speed constant frequency generating systems are used in wind power, hydro power, aerospace, and naval power generation to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising a doubly excited induction machine or a doubly excited brushless reluctance machine and PWM inverters with a DC link. A flexible active and

Yifan Tang; Longya Xu

1993-01-01

429

Adaptive fuzzy control of a variable speed power generating system with doubly excited reluctance machine  

Microsoft Academic Search

Fuzzy control methods are developed for a highly efficient variable speed constant frequency power generating system, with wind power generation as an example. In slip power recovery configuration, the system is composed of a doubly excited brushless reluctance-machine and a reduced rating power electronic converter unit linking the stator secondary circuit with the power line. The doubly excited brushless reluctance

Yifan Tang; Longya Xu

1994-01-01

430

A flexible active and reactive power control strategy for a variable speed constant frequency generating system  

Microsoft Academic Search

Variable-speed constant-frequency generating systems are used in wind power, hydroelectric power, aerospace, and naval power generation applications to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising a doubly excited induction machine or doubly excited brushless reluctance machine and PWM power converters with a DC link. In this paper, a flexible

Yifan Tang; Longya Xu

1995-01-01

431

Finite Bisimulation of Reactive Untimed Infinite State Systems Modeled as Automata with Variables  

E-print Network

1 Finite Bisimulation of Reactive Untimed Infinite State Systems Modeled as Automata with Variables for reactive untimed infinite state systems called input- output extended finite automaton (I/O-EFA), which analysis) is guaranteed when the software possesses a finite-state equiv- alent model. A contribution

Kumar, Ratnesh

432

Output Disturbance Decoupling Control of SISO Nonlinear Systems with Time Delay in State Variable  

Microsoft Academic Search

In this paper, the output disturbance decoupling problem (ODDP) for a single input single output (SISO) nonlinear systems with time delay in state variable is studied. The time delay operator is addressed and used to describe the nonlinear time delay systems. Then, the necessary and sufficient conditions for ODDP are achieved by applying extension Lie derivative and extension Lie bracket,

Bin Yang; Chen Ken; Chen Nana

2007-01-01

433

Description and test results of a variable speed, constant frequency generating system  

NASA Technical Reports Server (NTRS)

The variable-speed, constant frequency generating system developed for the Mod-0 wind turbine is presented. This report describes the system as it existed at the conclusion of the project. The cycloconverter control circuit is described including the addition of field-oriented control. The laboratory test and actual wind turbine test results are included.

Brady, F. J.

1985-01-01

434

The control of high-speed variable-reluctance generators in electric power systems  

Microsoft Academic Search

This work studies the control of a direct-current (DC) electric power system that is sourced by a variable-reluctance generator. The power system includes the generator and its switching inverter, a filtering capacitor, a distribution network and an electrical load. The network comprises a series resistor and inductor, while the load comprises a parallel resistor, capacitor and power sink. The voltage

D. E. Cameron; J. H. Lang

1993-01-01

435

The control of high-speed variable-reluctance generators in electric power systems  

Microsoft Academic Search

The control of a direct-current electric power system that is sourced by a variable-reluctance generator (VRG) is studied. The power system includes the generator and its switching inverter, a filtering capacitor, a distribution network, and an electrical load. The network comprises a series resistor and inductor, while the load comprises a parallel resistor, capacitor, and power sink. The voltage at

D. E. Cameron; J. H. Lang

1992-01-01

436

FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM  

EPA Science Inventory

The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

437

An intelligent maximum power extraction algorithm for inverter-based variable speed wind turbine systems  

Microsoft Academic Search

This paper focuses on the development of maximum wind power extraction algorithms for inverter-based variable speed wind power generation systems. A review of existing maximum wind power extraction algorithms is presented in this paper, based on which an intelligent maximum power extraction algorithm is developed by the authors to improve the system performance and to facilitate the control implementation. As

Quincy Wang; Liuchen Chang

2004-01-01

438

Design and Practical Implementation of a Novel Variable-Speed Generation System  

Microsoft Academic Search

This paper investigates a novel variable-speed gener- ation system. A new integrated power circuit with voltage clamp protection and self-excitation function is presented. Convention- ally, due to the large internal impedance of a generator, oscillations are produced by the resonances of the filter in armature currents which may cause unstable behavior of the generation system. In this paper, an active

Mingming Shi; Bo Zhou; Jiadan Wei; Zhuoran Zhang; Yiran Mao; Chu Han

2011-01-01

439

Exergy analysis of variable air volume systems for an office building  

Microsoft Academic Search

This paper presents the exergy analysis of variable air volume (VAV) systems used in office buildings for air-conditioning. The mathematical models are developed using the engineering equations solver (EES) environment. The following indicators are presented: energy efficiency, exergy efficiency, and equivalent-CO2 emissions due to the generation of electricity used by the VAV system.

Zhentao Wei; Radu Zmeureanu

2009-01-01

440

Modeling and experimental evaluation of an automotive air conditioning system with a variable capacity compressor  

Microsoft Academic Search

A steady state computer simulation model has been developed for refrigeration circuits of automobile air conditioning systems. The simulation model includes a variable capacity compressor and a thermostatic expansion valve in addition to the evaporator and micro channel parallel flow condenser. An experimental bench made up of original components from the air conditioning system of a compact passenger vehicle has

J. M. Saiz Jabardo; W. Gonzales Mamani; M. R. Ianella

2002-01-01

441

The Effect of Mass Transit Systems on Price of Condominium in Bangkok  

E-print Network

The Effect of Mass Transit Systems on Price of Condominium in Bangkok Undergraduate Honor Thesis condominiums near the mass transit route significantly as consumers are willing to pay more for the convenience. A hedonic price model is used to analyze the effect of mass transit systems on the price of condominiums

Sadoulet, Elisabeth

442

The distribution of mass and angular momentum in the solar system  

SciTech Connect

This book describes the contribution of the comets in the Oort cloud to the angular momentum of the solar system. Topics covered include: Nuclear mass of the new comets observed, Mass of the Oort cloud, Mass distribution in the solar system, Zone of comet formation, Angular momentum of the Oort cloud, and Angular momentum of the Hills cloud.

Marochnik, L.S.; Mukhin, L.M.; Sagdeev, R.Z. (Institute for Space Research, USSR Academy of Sciences, Moscow (SU))

1989-01-01

443

Dynamical Stability of Terrestrial Mass Planets in and around the Habitable Zones of Single Planet Systems  

Microsoft Academic Search

We discuss the dynamical stability of hypothetical terrestrial mass planets (1 -10 Earth masses) in the habitable zone (HZ) of systems which have an additional massive planet. We consider arbitrary masses and orbits, which cover the range of observed planetary system architectures. We determine stability through N-body simulations which we compare to the analytic \\

Ravi Kumar Kopparapu; R. Barnes

2010-01-01