These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Newton's second law for systems with variable mass  

Microsoft Academic Search

Rockets and other systems with variable mass require a modification of the usual form of Newton's second law. When a rocket is the prototype system, the derivation involves a confusing mixture of positive and negative terms. An alternative prototype system is proposed that simplifies the derivation by making all terms positive.

David Chandler

2000-01-01

2

Supernovae in cataclysmic variable systems and the formation of low-mass x-ray binaries  

Microsoft Academic Search

The impact effects of supernova explosion on a low-mass (M< or =1 M\\/sub sun\\/) companion in a cataclysmic variable system are investigated with respect to variations in the companion mass and the density and velocity of the supernova shell. For the cases considered here, the incident kinetic energies of the shell were typically greater than the binding energy of the

R. E. Taam; B. A. Fryxell

1984-01-01

3

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. ...

Ismail, Ahmed; Virzi, Joseph S; Walker, Devin G E

2014-01-01

4

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

5

Body mass index is related to autonomic nervous system activity as measured by heart rate variability  

Microsoft Academic Search

Autonomic nervous system activity is involved in body weight regulation. We assessed whether the body mass index (BMI) is related to the autonomic nervous system activity as assessed by heart rate variability (HRV). Twenty-five adult normotensive, euglycemic healthy males (M) and females (F) were studied (M\\/F=13\\/12). BMI was assessed in each individual. HRV was assessed and the domains of low

A Molfino; A Fiorentini; L Tubani; M Martuscelli; F Rossi Fanelli; A Laviano

2009-01-01

6

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS: Conservation Laws for Partially Conservative Variable Mass Systems via d'Alembert's Principle  

Microsoft Academic Search

Conservation laws for partially conservative variable mass dynamical systems under symmetric infinitesimal transformations are determined. A generalization of Lagrange-d'Alembert's principle for a variable mass system in terms of asynchronous virtual variation is presented. The generalized Killing equations are obtained such that their solution yields the transformations and the associated conservation laws. An example illustrative of the theory is furnished at

Ahmed Aftab; Ahmed Naseer; Khan Qudrat

2008-01-01

7

Dynamics of a variable mass system applied to spacecraft rocket attitude theory  

NASA Astrophysics Data System (ADS)

This research project is a study of the dynamics of a variable mass system. The scope of this research project is to gain understanding as to how a variable mass system will behave. The intent is to bring the level of understanding of variable mass dynamics higher and closer to the level of constant mass dynamics in the area of spacecrafts in particular. A main contribution is the finding of a set of criteria to minimize or eliminate the deviation of the nutation angle (or cone angle or angle of attack) of spacecraft rockets passively, i.e. without active control. The motivation for this research project is the Star 48 anomaly. The Star 48 is a solid rocket motor which has propelled (boosted) communication satellites from lower earth orbit to a higher one during the 1980's. The anomaly is that when the spacecraft rocket is being propelled, the nutation angle may deviate excessively which is considered undesirable. In the first part of this research project, a variable mass system is described and defined and the governing equations are derived. The type of governing equations derived are those that are most useful for analyzing the motion of a spacecraft rocket. The method of derivation makes use of Leibnitz Theorem, Divergence Theorem and Newton's Second Law of Motion. Next, the governing equations are specialized with several assumptions which are generally accepted assumptions applied in the analysis of spacecraft rockets. With these assumptions, the form governing equations is discussed and then the equations are solved analytically for the system's angular velocity. Having solved for the angular velocity of the system, the attitude of the system is obtained using a unique method which circumvents the nonlinearities that exist using Euler Angles and their kinematical equations. The attitude is approximately found analytically and a set of criteria is discussed which will minimize or eliminate the deviation of the nutation angle of a spacecraft rocket. Finally, an interesting scalar equation and vector equation is presented which sheds some light on the motion of a spacecraft rocket. The vector equation allows a geometric interpretation to be obtained which gives physical intuition to aid in designing a spacecraft rocket which will minimize or eliminate the deviation of the nutation angle.

Mudge, Jason Dominic

8

Earth? Mass Variability  

E-print Network

The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

Ramy Mawad

2014-02-12

9

Supernovae in cataclysmic variable systems and the formation of low-mass x-ray binaries  

SciTech Connect

The impact effects of supernova explosion on a low-mass (M< or =1 M/sub sun/) companion in a cataclysmic variable system are investigated with respect to variations in the companion mass and the density and velocity of the supernova shell. For the cases considered here, the incident kinetic energies of the shell were typically greater than the binding energy of the companion. Specific attention is focused on calculating the amount of momentum transferred to the companion star by the blast wave and by the nonplanar mass ablation that results. In no case was the binary system or companion disrupted. It is found that the efficiency of momentum transfer is greater for less massive companions. However, if the reduction in the companion's cross sectional area due to mass stripping is included in the definition of the incident shell momentum, the efficiency for our most realistic sequences is found to be greater for the more massive companions. An expression for this effective efficiency is presented whicch agrees with the computational results to within 10%. The variations in the orbital parmeters are small if a high-mass (M> or =1.2M/sub sun/) neutron star remnant is left after the explosion. Angular momentum loss by gravitational radition gives a duration for the postexplosion detached binary phase (after which the system becomes an X-ray binary) of greater than 10/sup 8/ years. The center-of-mass velocity imparted to the postexplosion binary is small (< or =18 km s/sup -1/) and is consistent with the spatial distribution of the strong X-ray sources observed in highly condensed globular clusters and in the galactic disk.

Taam, R.E.; Fryxell, B.A.

1984-04-01

10

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

11

Earth\\'s Mass Variability  

E-print Network

The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

Mawad, Ramy

2014-01-01

12

Insights into the Earth System mass variability from CSR-RL05 GRACE gravity fields  

NASA Astrophysics Data System (ADS)

The next-generation Release-05 GRACE gravity field data products are the result of extensive effort applied to the improvements to the GRACE Level-1 (tracking) data products, and to improvements in the background gravity models and processing methodology. As a result, the squared-error upper-bound in RL05 fields is half or less than the squared-error upper-bound in RL04 fields. The CSR-RL05 field release consists of unconstrained gravity fields as well as a regularized gravity field time-series that can be used for several applications without any post-processing error reduction. This paper will describe the background and the nature of these improvements in the data products, and provide an error characterization. We will describe the insights these new series offer in measuring the mass flux due to diverse Hydrologic, Oceanographic and Cryospheric processes.

Bettadpur, S.

2012-04-01

13

Variability of Coronal Mass Ejections  

NASA Astrophysics Data System (ADS)

Coronal mass ejections (CME) from the solar corona are the most spectacular phenomena of solar activity. Solar physicists are tried to relate CME with other forms of solar activities. CMEs are the result of a large scale rearrangement of solar magnetic field and they are often observed as an eruption of twisted magnetic fields from the solar atmosphere. SOHO/LASCO detected (http://cdaw.gsfc.nasa.gov/CME_list) more than 7500 CMEs during 1996-2003 June. The catalog contains all the CMEs with primary characteristics e.g. linear speed, central position angle, and the angular width. We will use these characteristics to study the variations of CME within these periods. The period starts from the sunspot minimum to entire sunspot maximum range where the solar activity is high. Solar proton events ( E>10MeV) were collected from NOAA website (http:/www.lep.gsfc.nasa.gov/waves) of the associated CMEs with halo CMEs. We find from CMEs data that the occurrence of average CME rate is 121.51 per month during June 1999 to June 2003 (sunspot maximum range) whereas the occurrence of average CME rate is 41.24 per month during January 1996 to May 1999 (sunspot minimum range), although during the year 1996 (when the average sunspot number is 8.6 per month) occurrence of average CME rate is 18.16 per month. The CME occurrence rate is also correlated with the sunspot numbers with high statistically significant level. The CME number is highest in 2002 but CME is higher in 2000 than in 2001. There is an overall similarity between sunspot number and CME rates but there are differences particularly from June 1999 which is the beginning of the sunspot maximum range. The CME rate peaks in September 2001 to October 2002, which is about 1.25 year after the sunspot maximum. Similarly the average speed of CME at the time of sunspot maximum range and sunspot minimum range are 575 km/sec. and 266 km/sec. respectively. This means that the average speed of CME increases from 1996 to June 2003. The CME speed is also correlated with the sunspot numbers with less significant level than the average rate of CME occurrence. The maximum monthly average speed is about 677.3 km/sec. at the time of April 2001, which is about 5 months earlier than the second sunspot maximum. From the preliminary list of halo CME events from SOHO/LASCO during January 1996 to June 2003 we find that the occurrence rate of average halo CME events during January 1996 to May 1999 is about 1.10 per month whereas during June 1999 to June 2003 is about 4.00 per month, during the year 1996 only two halo CMEs is occurred. We also find that the average speed of halo CME events during sunspot minimum range is 838 km/sec, whereas average speed of the halo CME events during sunspot maximum range is 1000 km/sec. Although during the year 1996 the average speed of halo CME events is 451 km/sec. From the characteristics of halo CMEs in years we find that the number of halo CME increases from 1996 to 2001 and the number of halo CME is maximum in the year 2001, after that number of halo CME decreases. In the 23rd solar cycle maximum solar activity occurred during June to September 2001 we call the time as 2nd sunspot maximum time. We also find that number of high speed ( >1000 km/sec.) halo CME is highest during 2nd sunspot maximum range (i.e., during 2001-2002). We find from the halo CME data that average halo CME speed increases from 1996 to 1998 and then decreases from 1998 to 2000 and again increases from 2000 to 2003 and we expect that the average speed of halo CME will decrease after 2003. We find 78 solar proton events (E >10MeV) from CME and about 43 of them are from halo CME during 1996 to 2003. We noticed that the maximum solar proton events occurred at the second sunspot maximum, which is occurred after 1/12 sunspot maximum in the 23rd solar cycle. We find there exist 5 phases of solar proton events (E >10MeV) data in the 23rd solar cycle. The first phase is at the sunspot minimum, 2nd phase is after two years from the sunspot minimum, 3rd phase is at the time of sunspot maximu

Raychaudhuri, Probhas

14

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

15

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

16

Jets impactants masse volumique variable J. DUBOISa,  

E-print Network

Jets impactants à masse volumique variable J. DUBOISa, b, M. AMIELHA , F. ANSELMETA , O (Background Oriented Schlieren) when the jet is impacting a sphere placed in the nearfield. M o t s clefs: Jet dans la région de développement du jet de fuite. Le mélange avec l'air ambiant d'un jet d

Boyer, Edmond

17

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

E-print Network

of possible future sea- level rise (Church and others, 2001; ISMASS Committee, 2004; Wigley, 2005). Recently (Church and others, 2001). Subsequent estimates by the mass-budget method indicate the 20th-century Antarctic mass imbalance seems near to zero or slightly negative (Rignot and Thomas, 2002; ISMASS Committee

Huybrechts, Philippe

18

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

19

Mass Functions Density Functions Random Variables and Distribution Functions  

E-print Network

Mass Functions Density Functions Topic 7 Random Variables and Distribution Functions Mass Functions and Density Functions 1 / 9 #12;Mass Functions Density Functions Outline Mass Functions Density Functions 2 / 9 #12;Mass Functions Density Functions Mass Functions The (probability) mass function of a discrete

Watkins, Joseph C.

20

Investigation of the three-body-points problem with variable masses using the analytical calculation system ``Mathematica": Theory  

NASA Astrophysics Data System (ADS)

The equations of motion of the investigated problem are obtained in the osculating elements of an aperiodic motion at the quasiconic section. Secular parts of the perturbing functions are calculated in terms of the osculating canonical elements with the use of the system ``Mathematica". Full first-order secular perturbations are obtained by the method of Picard.

Minglibayev, M. Zh.; Mayemerova, G. M.

2013-08-01

21

The period gap and masses of cataclysmic variables  

NASA Astrophysics Data System (ADS)

Consequences of the currently-favored view that the cataclysmic variable period gap results from a sharp decrease in orbital braking once the secondary becomes fully convective are examined. It is shown that the period distribution of systems near the edge of the gap imposes, for a given stellar model, tight constraints on the parameters of the Mestel-Spruit magnetic braking law. The white dwarf mass M1 in systems such as TU Men or YZ Cnc must be high, unless these systems are assumed coincidentally to have been born close to the upper edge of the gap. With the present adopted parameters, M1 of not less than 1 solar mass is predicted for both systems. Observational mass determination for these systems and those which should be discovered by Rosat thus offer a stringent test of current theories of the period gap. It is shown that, depending on the secondary mass and age when it first comes into contact, evolution can be driven by angular momentum losses either through magnetic braking or gravitational radiation, and that for periods greater than 2.5-2.6 h, high mass transfer rates are possible, as observed in V795 Her.

Hameury, J. M.; King, A. R.; Lasota, J. P.

1991-08-01

22

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

23

Rotation and variability of young very low mass objects  

E-print Network

Variability studies are an important tool to investigate key properties of stars and brown dwarfs. From photometric monitoring we are able to obtain information about rotation and magnetic activity, which are expected to change in the mass range below 0.3 solar masses, since these fully convective objects cannot host a solar-type dynamo. On the other hand, spectroscopic variability information can be used to obtain a detailed view on the accretion process in very young objects. In this paper, we report about our observational efforts to analyse the variability and rotational evolution of young brown dwarfs and very low mass stars.

Alexander Scholz; Ray Jayawardhana; Jochen Eisloeffel; Dirk Froebrich

2005-08-23

24

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

25

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

26

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

27

Guide to transverse projections and mass-constraining variables  

E-print Network

This paper seeks to demonstrate that many of the existing mass-measurement variables proposed for hadron colliders (mT, mEff, mT2, missing pT, hT, rootsHatMin, etc.) are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass bound specialized for a variety of purposes. A consequence of this is that one may understand better the strengths and weaknesses of each variable, and the circumstances in which each can be used to best effect. In order to achieve this, we find it necessary first to revisit the seemingly empty and infertile wilderness populated by the subscript "T" (as in pT) in order to remind ourselves what this process of transversification actually means. We note that, far from being simple, transversification can mean quite different things to different people. Those readers who manage to battle through the barrage of transverse notation distinguishing mass-preserving projections from velocity preserving projections, and `early projection' from `late projection', will find their efforts rewarded towards the end of the paper with (i) a better understanding of how collider mass variables fit together, (ii) an appreciation of how these variables could be generalized to search for things more complicated than supersymmetry, (iii) will depart with an aversion to thoughtless or naive use of the so-called `transverse' methods of any of the popular computer Lorentz-vector libraries, and (iv) will take care in their subsequent papers to be explicit about which of the 61 identified variants of the `transverse mass' they are employing.

A. J. Barr; T. J. Khoo; P. Konar; K. Kong; C. G. Lester; K. T. Matchev; M. Park

2011-05-15

28

Variability and Rotation in Low Mass Stars and Brown Dwarfs  

Microsoft Academic Search

The evolution of angular momentum in stars is not really understood today. In particular, very little is known about rotation\\u000a of substellar objects. Therefore, we started a systematic search for periodic variability in very low mass (VLM) stars and\\u000a Brown Dwarfs. From a deep multi-filter survey of the young open cluster IC4665, accompanied by follow-up spectroscopy with\\u000a FORS at the

Jochen Eislffel; Alexander Scholz

2002-01-01

29

Guide to transverse projections and mass-constraining variables  

NASA Astrophysics Data System (ADS)

This paper seeks to demonstrate that many of the existing mass-measurement variables proposed for hadron colliders (mT, meff, mT2, missing p?T, hT, s^min?, etc.) are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass-bound specialized for a variety of purposes. A consequence of this is that one may understand better the strengths and weaknesses of each variable, and the circumstances in which each can be used to best effect. In order to achieve this, we find it necessary first to revisit the seemingly empty and infertile wilderness populated by the subscript T (as in p?T) in order to remind ourselves what this process of transversification actually means. We note that, far from being simple, transversification can mean quite different things to different people. Those readers who manage to battle through the barrage of transverse notation distinguishing ? from ? or from ?, and early projection from late projection, will find their efforts rewarded towards the end of the paper with (i) a better understanding of how collider mass variables fit together, (ii) an appreciation of how these variables could be generalized to search for things more complicated than supersymmetry, (iii) will depart with an aversion to thoughtless or nave use of the so-called transverse methods of any of the popular computer Lorentz-vector libraries, and (iv) will take care in their subsequent papers to be explicit about which of the 61 identified variants of the transverse mass they are employing.

Barr, A. J.; Khoo, T. J.; Konar, P.; Kong, K.; Lester, C. G.; Matchev, K. T.; Park, M.

2011-11-01

30

Guide to transverse projections and mass-constraining variables  

SciTech Connect

This paper seeks to demonstrate that many of the existing mass-measurement variables proposed for hadron colliders (m{sub T}, m{sub eff}, m{sub T2}, missing p-vector{sub T}, h{sub T}, {radical}(s-circumflex){sub min}, etc.) are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass-bound specialized for a variety of purposes. A consequence of this is that one may understand better the strengths and weaknesses of each variable, and the circumstances in which each can be used to best effect. In order to achieve this, we find it necessary first to revisit the seemingly empty and infertile wilderness populated by the subscript 'T' (as in 'pe{sub T}') in order to remind ourselves what this process of transversification actually means. We note that, far from being simple, transversification can mean quite different things to different people. Those readers who manage to battle through the barrage of transverse notation distinguishing 'T' from 'v' or or from 'o', and 'early projection' from 'late projection', will find their efforts rewarded towards the end of the paper with (i) a better understanding of how collider mass variables fit together, (ii) an appreciation of how these variables could be generalized to search for things more complicated than supersymmetry, (iii) will depart with an aversion to thoughtless or naieve use of the so-called 'transverse methods' of any of the popular computer Lorentz-vector libraries, and (iv) will take care in their subsequent papers to be explicit about which of the 61 identified variants of the 'transverse mass' they are employing.

Barr, A. J. [Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Khoo, T. J.; Lester, C. G. [Department of Physics, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE (United Kingdom); Konar, P. [Theoretical Physics Group, Physical Research Laboratory, Ahmedabad, Gujarat - 380 009 (India); Kong, K. [Department of Physics and Astronomy, University of Kansas, Lawrence, KA 66045 (United States); Matchev, K. T.; Park, M. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)

2011-11-01

31

Inter- and intra-observer variability in radiologists' assessment of mass similarity on mammograms  

NASA Astrophysics Data System (ADS)

The purpose of this study was to compare the performances of two recently-developed image retrieval methods for mammographic masses, and to investigate the inter- and intra-observer variability in radiologists' assessment of mass similarity. Method 1 retrieved masses that are similar to a query mass from a reference library based on radiologists' margin and shape descriptions and the mass size. Method 2 used computer-extracted features. Two MQSA radiologists participated in an observer study in which they rated the similarity between 100 query masses and the retrieved lesions based on margins, shape, and size. For each query mass, three masses retrieved using Method 1 and three masses retrieved using Method 2 were displayed in random order using a graphical user interface. A nine-point similarity rating scale was used, with a rating of 1 indicating lowest similarity. Each radiologist repeated the readings twice, separated by more than three months, so that intra-observer variability could be studied. Averaged over the two radiologists, two readings, and all masses, the mean similarity ratings were 5.59 and 5.57 for Methods 1 and 2, respectively. The difference between the two methods did not reach significance (p>0.20) for either radiologist. The intra-observer variability was significantly lower than the inter-observer variability, which may indicate that each radiologist may have their image similarity criteria, and the criteria may vary from radiologist to radiologist. The understanding of the trends in radiologists' assessment of mass similarity may guide the development of decision support systems that make use of mass similarity to aid radiologists in mammographic interpretation.

Sahiner, Berkman; Hadjiiski, Lubomir M.; Chan, Heang-Ping; Cui, Jing; Paramagul, Chintana; Nees, Alexis; Helvie, Mark

2009-02-01

32

Variable friction pendulum system for seismic isolation of liquid storage tanks  

Microsoft Academic Search

Earthquake response of liquid storage steel tanks isolated with variable friction pendulum system (VFPS) is investigated under normal component of six recorded near-fault ground motions. The continuous liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The corresponding stiffness constants associated with these lumped masses are worked out depending upon

V. R. Panchal; R. S. Jangid

2008-01-01

33

Optimally Invariant Variable Combinations for Nonlinear Systems  

E-print Network

Optimally Invariant Variable Combinations for Nonlinear Systems Johannes E. P. J¨aschke, Sigurd constraints, it is shown that there exist some optimally invariant variable combination for each region. If the unknown variables can be eliminated by measurements and system equations, the invariant combinations can

Skogestad, Sigurd

34

Long-term variability of low-mass X-ray binaries  

NASA Astrophysics Data System (ADS)

We consider modulations of mass captured by the compact object from the companion star's stellar wind in Low Mass X-ray Binaries with late type giants. Based on 3D simulations with two different hydrodynamic codes used Lagrangian and Eulerian approaches - the SPH code GADGET and the Eulerian code PLUTO, we conclude that a hydrodynamical interaction of the wind matter within a binary system even without eccentricity results in variability of the mass accretion rate with characteristic time-scales close to the orbital period. Observational appearances of this wind might be similar to that of an accretion disc corona/wind.

Filippova, E.; Revnivtsev, M.; Parkin, E. R.

2014-01-01

35

System Response Improvement by State Variable Feedback  

Microsoft Academic Search

The technique of applying state variable feedback methods to an existing control system is presented. The system response is improved through a redesign of the feedback elements of the original system having predetermined the desired closed-loop response. This improvement in response results from a reformulation of the system description in a state variable format leading to the feedback gains necessary

Willie Mc Daniel; Perry Davis

1969-01-01

36

Propagating variability from technology to system level  

Microsoft Academic Search

As CMOS technology feature sizes decrease, variability more and more jeopardizes system level parametric and functional yield. This paper proposes a framework that can capture variability at all levels in the design flow. It offers a correlated view on yield, timing, dynamic and static energy. Preservation on rare events in variability distributions is obtained by the Weighted Monte Carlo technique.

Bart Dierickx; Miguel Miranda; Petr Dobrovolny; Florian Kutscherauer; Antonis Papanikolaou; P. Marchal

2007-01-01

37

Future climate warming increases Greenland ice sheet surface mass balance variability  

NASA Astrophysics Data System (ADS)

The integrated surface mass balance (SMB) of the Greenland ice sheet (GrIS) has large interannual variability. Long-term future changes to this variability will affect GrIS dynamics, freshwater fluxes, regional oceanography, and detection of changes in ice volume trends. Here we analyze a simulated 1850-2100 GrIS SMB time series from the Community Earth System Model, currently the only global climate model that realistically simulates GrIS SMB. We find a significant increase in interannual integrated SMB variability over time, which we attribute primarily to a shift to a high-variability melt-dominated SMB regime due to GrIS ablation area growth. We find temporal increases to characteristic ablation and accumulation area-specific SMB variabilities to be of secondary importance. Since ablation area SMB variability is driven largely by variability in summer surface melt, variability in the climate processes regulating the energy fluxes that control melting will likely increasingly determine future GrIS SMB variability.

Fyke, Jeremy G.; Vizcano, Miren; Lipscomb, William; Price, Stephen

2014-01-01

38

Spinor Slow-Light and Dirac Particles with Variable Mass  

SciTech Connect

We consider the interaction of two weak probe fields of light with an atomic ensemble coherently driven by two pairs of standing wave laser fields in a tripod-type linkage scheme. The system is shown to exhibit a Dirac-like spectrum for light-matter quasiparticles with multiple dark states, termed spinor slow-light polaritons. They posses an 'effective speed of light' given by the group velocity of slow light, and can be made massive by inducing a small two-photon detuning. Control of the two-photon detuning can be used to locally vary the mass including a sign flip. Particularly, this allows the implementation of the random-mass Dirac model for which localized zero-energy (midgap) states exist with unusual long-range correlations.

Unanyan, R. G.; Otterbach, J.; Fleischhauer, M.; Ruseckas, J.; Kudriasov, V.; Juzeliunas, G. [Department of Physics and Research Center OPTIMAS, Technische Universitaet Kaiserslautern, 67663 Kaiserslautern (Germany); Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania)

2010-10-22

39

Short time-scale AGN X-ray variability with EXOSAT: black hole mass and normalized variability amplitude  

NASA Astrophysics Data System (ADS)

The old EXOSAT medium energy measurements of high-frequency (HF) active galactic nuclei (AGN) power spectral normalization are re-examined in the light of accurate black hole mass determinations which were not available when these data were first published by Green et al. It is found that the normalized variability amplitude (NVA), measured directly from the power spectrum, is proportional to M?, where ? -0.54 0.08. As NVA is the square root of the power, these observations show that the normalization of the HF power spectrum for this sample of AGN varies very close to inversely with black hole mass. Almost the same value of ? is obtained whether the quasar 3C 273 is included in the sample or not, suggesting that the same process that drives X-ray variability in Seyfert galaxies applies also to 3C 273. These observations support the work of Gierli?ski et al. who show that an almost exactly linear anticorrelation is required if the normalizations of the HF power spectra of AGN and X-ray binary systems are to scale similarly. These observations are also consistent with a number of studies showing that the short time-scale variance of AGN X-ray light curves varies approximately inversely with mass.

McHardy, I. M.

2013-03-01

40

Water mass and throughflow transport variability in the Taiwan Strait  

NASA Astrophysics Data System (ADS)

Variability of water mass and throughflow transport in the Taiwan Strait are analyzed using strait-wide conductivity-temperature-depth (1985-2003) and sectional acoustic Doppler current profiler (1999-2001) data. Results from a cluster analysis, temperature-salinity diagrams, and direct transport calculations indicate that the strong northeast monsoon drives the brackish Mixed China Coastal Water into the northern strait and hinders the northward intruded saline Kuroshio Branch Water (KBW) in the southeastern strait from December to January. The mean throughflow transport across the central strait is about 0.1 Sv southward during this period, thus supporting previous observations that there is no persistent northward flowing current throughout the strait in winter. The weakening of the northeast monsoon in February-March, however, emancipates the KBW to intrude northward into the East China Sea (ECS). In June, the increase in this northward transport accompanied by the decrease in the westward intrusion of Kuroshio through the Luzon Strait leads to the replacement of the KBW by the less saline South China Sea Water (SCSW). The northward transports ranging from 1.16 to 2.34 Sv between March and August yield 0.131-0.238 1015 W and 53.33-81.74 106 kg/s of temperature and salt transports, respectively, toward the ECS. The inception of the northeast monsoon in October marks both the change of water mass from fall to winter patterns and the decrease of the northward throughflow transport. Our results also reveal that the subsurface KBW and SCSW remain consistent throughout the observation periods between 100 and 200 m and below 200 m depths, respectively, in the southeastern strait.

Jan, Sen; Sheu, David D.; Kuo, Huei-Ming

2006-12-01

41

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

42

Infrared Properties of Cataclysmic Variables from 2MASS: Results from the 2nd Incremental Data Release  

E-print Network

Because accretion-generated luminosity dominates the radiated energy of most cataclysmic variables, they have been ``traditionally'' observed primarily at short wavelengths. Infrared observations of cataclysmic variables contribute to the understanding of key system components that are expected to radiate at these wavelengths, such as the cool outer disk, accretion stream, and secondary star. We have compiled the J, H, and Ks photometry of all cataclysmic variables located in the sky coverage of the 2 Micron All Sky Survey (2MASS) 2nd Incremental Data Release. This data comprises 251 systems with reliably identified near-IR counterparts and S/N > 10 photometry in one or more of the three near-IR bands.

D. W. Hoard; S. Wachter; L. Lee Clark; Timothy P. Bowers

2001-09-21

43

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

1999-08-17

44

Variable low-mass filtering using an electrodynamic ion funnel.  

PubMed

An adjustable low-mass filter has been developed for an electrospray ionization (ESI) source to block ions associated with unwanted background species from entering the mass spectrometer. The low-mass filter is made by using an adjustable potential energy barrier from the conductance-limiting plate of an electrodynamic ion funnel, which prohibits species with higher ion mobilities from exiting the ESI source. We show that this arrangement provides a linear voltage adjustment for low-mass filtering from m/z 0 to 500. Mass filtering above m/z 500 is also performed; however, higher-mass species are attenuated. The mass filter was tested with a liquid chromatography/mass spectrometry (LC/MS) analysis of a bovine serum albumin (BSA) tryptic digest and resulted in the ability to block low-mass, background species, which accounted for 40-70% of the total ion current immediately behind the ESI source during peak elution and detection. PMID:16127660

Page, Jason S; Tolmachev, Aleksey V; Tang, Keqi; Smith, Richard D

2005-09-01

45

Random Fuzzy Variable Modeling on Repairable System  

Microsoft Academic Search

Repairable system analysis is in nature an evaluation of repair effects. Recent tendency in reliability engineering literature was imposing repair regimes and estimate system repair effects or linking repair to certain covariate to extract repair impacts. Hinted by engineering tune up exercises, we propose a repair model in terms of random variable distribution with a fuzzy parameter because fuzziness reflects

R. Guo; R. Q. Zhao; D. Guo; T. Dunne

46

Mass Transfer in Binary Star Systems  

NSDL National Science Digital Library

An overview of the process of mass loss of a Star is explained, specifically if the Star is in a Binary System. The website goes through the mass transfer process, its mechanisms, and its consequences.

Seligman, Courtney

2007-06-05

47

Variable low-mass filtering using an electrodynamic ion funnel  

SciTech Connect

An adjustable, low mass-to-charge (m/z) filter has been developed and demonstrated using electrospray ionization to block ions associated with unwanted low m/z species from entering the mass spectrometer and contributing their space charge to down-stream ion accumulation steps. The low-mass filter is made by using an adjustable potential energy barrier from the conductance limiting terminal electrode of an electrodynamic ion funnel, which prohibits species with higher ion mobilities from being transmitted. We show that this arrangement provides a linear voltage adjustment of low-mass filtering from m/z 50 to 500. Mass filtering above m/z 500 can also be performed; however, higher m/z species are attenuated. The mass filter was evaluated with a liquid chromatography-mass spectrometry analysis of an albumin tryptic digest and resulted in the ability to block low-mass, ''background'' ions which account for 40-70% of the total ion current from the ESI source during peak elution.

Page, Jason S.; Tolmachev, Aleksey V.; Tang, Keqi; Smith, Richard D.

2005-08-26

48

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-Garca, Javier; Catelan, Mrcio; Ramos, Rodrigo Contreras; Gran, Felipe; Amigo, Pa; Leyton, Paul; Minniti, Dante

2014-01-01

49

The winds of Luminous Blue Variables and the Mass of AG Car  

E-print Network

We present radiation-driven wind models for Luminous Blue Variables (LBVs) and predict their mass-loss rates. A comparison between our predictions and the observations of AG Car shows that the variable mass loss behaviour of LBVs is due the recombination/ionisation of Fe IV/III and Fe III/II. We also derive a present-day mass of 35 Msun for AG Car.

Jorick S. Vink; Alex de Koter

2002-07-15

50

The turbulent mean-flow, Reynolds-stress, and heat flux equations in mass-averaged dependent variables  

NASA Technical Reports Server (NTRS)

The time-dependent, turbulent mean-flow, Reynolds stress, and heat flux equations in mass-averaged dependent variables are presented. These equations are given in conservative form for both generalized orthogonal and axisymmetric coordinates. For the case of small viscosity and thermal conductivity fluctuations, these equations are considerably simpler than the general Reynolds system of dependent variables for a compressible fluid and permit a more direct extension of low speed turbulence modeling to computer codes describing high speed turbulence fields.

Rubesin, M. W.; Rose, W. C.

1973-01-01

51

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

52

Optimally Invariant Variable Combinations for Nonlinear Systems  

E-print Network

Optimally Invariant Variable Combinations for Nonlinear Systems Johannes E. P. J¨aschke Sigurd for achieving optimal operation, by performing all calculations off-line and by determining optimally invariant steps. First, regions of constant active constraints are defined. Second, optimally invariant nonlinear

Skogestad, Sigurd

53

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

54

Regulation of a system with variable structure  

NASA Astrophysics Data System (ADS)

The linearized process dynamics of the boiler in a solar-powered central receiver change abruptly when clouds pass over the heliostats which direct the sun's rays toward it. The steam temperature regulator used to control exit steam conditions must control a system with variable structure and discontinuous state trajectories. This paper investigates the quadratic-optimal control of such a system and gives the design equations for the optimal regulator.

Sworder, D. D.

55

Mass-losing Semiregular Variable Stars in Baade's Windows  

Microsoft Academic Search

By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 mum) and MACHO V and R light curves are assembled for approximately 300 stars in the Baade's windows of low extinction toward the Galactic bulge. These stars are mainly giants of

C. Alard; J. A. D. L. Blommaert; C. Cesarsky; N. Epchtein; M. Felli; P. Fouque; S. Ganesh; R. Genzel; G. Gilmore; I. S. Glass; H. Habing; A. Omont; M. Perault; S. Price; A. Robin; M. Schultheis; G. Simon; J. Th. van Loon; C. Alcock; R. A. Allsman; D. R. Alves; T. S. Axelrod; A. C. Becker; D. P. Bennett; K. H. Cook; A. J. Drake; K. C. Freeman; M. Geha; K. Griest; M. J. Lehner; D. Minniti; C. Nelson; B. A. Peterson; P. Popowski; M. R. Pratt; P. J. Quinn; W. Sutherland; A. B. Tomaney; T. Vandehei; D. L. Welch

2001-01-01

56

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

57

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

58

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

59

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

60

[Variability of the deep femoral venous system].  

PubMed

Deep venous system is known for its extreme variability but in anatomy it receives only marginal interest. Although a few previous anatomical studies have already pointed out the fact of a significant discrepancy between the autopsy findings and the literary description, it has not had any particular output so far. Our findings confirmed the deep femoral vein to be an alternative collateral vein connecting the popliteal with the femoral vein. PMID:21751509

Eberlov, Lada; Tolar, Jakub; Mikuls, Jan; Valenta, Jir; Kocov, Jitka; Hirmerov, Jana; Fiala, Pavel

2011-01-01

61

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

62

A study of variable thrust, variable specific impulse trajectories for solar system exploration  

NASA Astrophysics Data System (ADS)

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines; but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.

Sakai, Tadashi

63

Greenland Ice Sheet Surface Mass Balance Variability (19882004) from Calibrated Polar MM5 Output*  

E-print Network

of Greenland ice sheet surface mass balance (SMB) change over a 17-yr period characterized by warming (1988 SMB trend. However, a 30% increase in meltwater runoff over this period suggests that the overall ice. SMB temporal variability of the whole ice sheet is best represented by ablation zone variability

Howat, Ian M.

64

MASS: An automated accountability system  

SciTech Connect

All Department of Energy contractors who manage accountable quantities of nuclear materials are required to implement an accountability system that tracks, and records the activities associated with those materials. At Los Alamos, the automated accountability system allows data entry on computer terminals and data base updating as soon as the entry is made. It is also able to generate all required reports in a timely Fashion. Over the last several years, the hardware and software have been upgraded to provide the users with all the capability needed to manage a large variety of operations with a wide variety of nuclear materials. Enhancements to the system are implemented as the needs of the users are identified. The system has grown with the expanded needs of the user; and has survived several years of changing operations and activity. The user community served by this system includes processing, materials control and accountability, and nuclear material management personnel. In addition to serving the local users, the accountability system supports the national data base (NMMSS). This paper contains a discussion of several details of the system design and operation. After several years of successful operation, this system provides an operating example of how computer systems can be used to manage a very dynamic data management problem.

Erkkila, B.H.; Kelso, F.

1994-08-01

65

On the use and abuse of Newton's second law for variable mass problems  

Microsoft Academic Search

We clarify some misunderstandings currently found in the literature that arise from improper application of Newton's second law to variable mass problems. In the particular case of isotropic mass loss, for example, several authors introduce a force that actually does not exist.

Angel R. Plastino; Juan C. Muzzio

1992-01-01

66

A mass-selective variable-temperature drift tube ion mobility-mass spectrometer for temperature dependent ion mobility studies.  

PubMed

A hybrid ion mobility-mass spectrometer (IM-MS) incorporating a variable-temperature (80-400K) drift tube is presented. The instrument utilizes an electron ionization (EI) source for fundamental small molecule studies. Ions are transferred to the IM-MS analyzer stages through a quadrupole, which can operate in either broad transmission or mass-selective mode. Ion beam modulation for the ion mobility experiment is accomplished by an electronic shutter gate. The variable-temperature ion mobility spectrometer consists of a 30.2cm uniform field drift tube enclosed within a thermal envelope. Subambient temperatures down to 80K are achievable through cryogenic cooling with liquid nitrogen, while elevated temperatures can be accessed through resistive heating of the envelope. Mobility separated ions are mass analyzed by an orthogonal time-of-flight (TOF) mass spectrometer. This report describes the technological considerations for operating the instrument at variable temperature, and preliminary results are presented for IM-MS analysis of several small mass ions. Specifically, mobility separations of benzene fragment ions generated by EI are used to illustrate significantly improved (greater than 50%) ion mobility resolution at low temperatures resulting from decreased diffusional broadening. Preliminary results on the separation of long-lived electronic states of Ti(+) formed by EI of TiCl(4) and hydration reactions of Ti(+) with residual water are presented. PMID:21953095

May, Jody C; Russell, David H

2011-07-01

67

Modelling of Sigma Scorpii, a high-mass binary with a Beta Cep variable primary component  

E-print Network

High-mass binary stars are known to show an unexplained discrepancy between the dynamical masses of the individual components and those predicted by models. In this work, we study Sigma Scorpii, a double-lined spectroscopic binary system consisting of two B-type stars residing in an eccentric orbit. The more massive primary component is a Beta Cep-type pulsating variable star. Our analysis is based on a time-series of some 1000 high-resolution spectra collected with the CORALIE spectrograph in 2006, 2007, and 2008. We use two different approaches to determine the orbital parameters of the star; the spectral disentangling technique is used to separate the spectral contributions of the individual components in the composite spectra. The non-LTE based spectrum analysis of the disentangled spectra reveals two stars of similar spectral type and atmospheric chemical composition. Combined with the orbital inclination angle estimate found in the literature, our orbital elements allow a mass estimate of 14.7 +/- 4.5 a...

Tkachenko, A; Pavlovski, K; Degroote, P; Papics, P I; Moravveji, E; Lehmann, H; Kolbas, V; Clemer, K

2014-01-01

68

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

69

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

70

A comparison of two total contact cast constructs with variable body mass.  

PubMed

Objective: There is a growing body of evidence implicating obesity as having a negative effect on the development and treatment of diabetic foot disease. The aim of this study was to increase the body of knowledge on the effects of obesity on foot function, specifically as it relates to peak plantar pressures in the total contact cast (TCC). Our investigational objectives were to compare the effect of two different TCC designs on mean peak plantar pressures, and to evaluate the efficacy of two TCC constructs with increasing body mass. Method: The primary outcome measure was mean peak plantar pressure in the heel, midfoot, forefoot and first metatarsal as measured with an in-shoe pressure measurement system. The variables were patient weight (from 'normal' body mass index (BMI) to 'overweight', 'obese' and 'morbidly obese') and the TCC construct (with both a standard and alternate cast design). The standard TCC is considered the gold standard for off-loading of the diabetic foot. The alternate TCC was designed to use the essential offloading component of the traditional TCC, namely the total contact leg section, with use of an open cell polyurethane foam to transfer load from the foot to the lower leg, thereby offloading the foot by suspending it within a padded fiberglass walking cast. Results: We did not observe statistically significant differences in mean peak plantar pressures in any plantar foot anatomic area or with any body mass between the two TCC designs. Conclusion: Based on the results, we concluded that the alternate TCC design provides another viable TCC construct option for practitioners working with the neuropathic foot. This investigation also provides specific data on changes that occur in peak plantar pressures with use of the total contact cast and variable BMIs. Declaration of interest: none. PMID:25041431

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

2014-07-01

71

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

72

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

73

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

74

Investigating mass transfer in symbiotic systems with hydrodynamic simulations  

NASA Astrophysics Data System (ADS)

We investigate gravitationally focused wind accretion in binary systems consisting of an evolved star with a gaseous envelope and a compact accreting companion. We study the mass accretion and formation of an accretion disk around the secondary caused by the strong wind from the primary late-type component using global 2D and 3D hydrodynamic numerical simulations. In particular, the dependence on the mass accretion rate on the mass loss rate, wind temperature and orbital parameters of the system is considered. For a typical slow and massive wind from an evolved star the mass transfer through a focused wind results in rapid infall onto the secondary. A stream flow is created between the stars with accretion rates of a 2-10% percent of the mass loss from the primary. This mechanism could be an important method for explaining periodic modulations in the accretion rates for a broad range of interacting binary systems and fueling of a large population of X-ray binary systems. We test the plausibility of these accretion flows indicated by the simulations by comparing with observations of the symbiotic CH Cyg variable system.

de Val-Borro, Miguel; Karovska, Margarita; Sasselov, Dimitar D.

2014-06-01

75

Mass flow fuel injection control system  

Microsoft Academic Search

A mass flow fuel injection control system is described for an internal combustion engine having air intake means supplying combustion air to the engine, and fuel injector means supplying fuel to the engine. The control system consists of: air flow velocity sensing means comprising venturi means in the air intake means producing a pressure drop, and means measuring the differential

Staerzl

1988-01-01

76

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

77

Evaluating Surface Mass Balance spatiotemporal variability in a regional climate model over Greenland using an ice sheet model and GRACE  

NASA Astrophysics Data System (ADS)

The Surface Mass Balance (SMB) of the Greenland Ice Sheet (GIS) is an important contributor to changes in sea level, now, and in the future. Both modeling and observational studies have revealed accelerating loss of mass over Greenland, of which approximately 50% has been attributed to changes in SMB, with the other 50% coming from increases in glacial discharge. Regional Climate Model (RCM) estimates of SMB change are currently among the best means of obtaining estimates of SMB timeseries. Measurements of SMB over the GIS are sparse, limiting the ability to validate SMB estimates. Several studies have compared ice-sheet wide changes in mass measured by the Gravity Recovery and Climate Experiment (GRACE), satellite-derived ice discharge measurements, and RCM results, to reveal a general agreement in ice-sheet wide mass changes over the past decade, but no detailed analysis of the spatiotemporal variability of simulated SMB estimates has been conducted using these datasets. Here we make use of a high resolution gridded 50 km GRACE Mascon solution at a monthly temporal resolution, satellite-derived discharge estimates, and sub-annual estimates of mass change from the Ice Sheet System Model (ISSM), to evaluate spatiotemporal variability in SMB simulated by the Modle Atmosphrique Rgionale (MAR), a regional climate model applied over the GIS. We reveal spatial biases in MAR SMB, but find a general agreement for GIS-wide SMB fluctuations. A lag in the seasonal cycle of mass loss potentially reveals a water storage cycle in ablation zone areas.

Alexander, P. M.; Tedesco, M.; Luthcke, S. B.; Schlegel, N.; Larour, E. Y.; Fettweis, X.

2013-12-01

78

Cataclysmic variables from a ROSAT/2MASS selection I: Four new intermediate polars  

E-print Network

We report the first results from a new search for cataclysmic variables (CVs) using a combined X-ray (ROSAT) / infrared (2MASS) target selection that discriminates against background AGN. Identification spectra were obtained at the Isaac Newton Telescope for a total of 174 targets, leading to the discovery of 12 new CVs. Initially devised to find short-period low-mass-transfer CVs, this selection scheme has been very successful in identifying new intermediate polars. Photometric and spectroscopic follow-up observations identify four of the new CVs as intermediate polars: 1RXSJ063631.9+353537 (Porb~201min, Pspin=1008.3408s or 930.5829), 1RXSJ070407.9+262501 (Porb~250min, Pspin=480.708s), 1RXSJ173021.5-055933 (Porb=925.27min, Pspin=128.0s), and 1RXSJ180340.0+401214 (Porb=160.21min, Pspin=1520.51s). RXJ1730, also a moderately bright hard X-ray source in the INTEGRAL/IBIS Galactic plane survey, resembles the enigmatic AE Aqr. It is likely that its white dwarf is not rotating at the spin equilibrium period, and the system may represent a short-lived phase in CV evolution.

B. T. Gaensicke; T. R. Marsh; A. Edge; P. Rodriguez-Gil; D. Steeghs; S. Araujo-Betancor; E. Harlaftis; O. Giannakis; S. Pyrzas; L. Morales-Rueda; A. Aungwerojwit

2005-04-21

79

High-resolution infrared spectra of FU Orionis variables - Keplerian rotation and mass loss  

SciTech Connect

High-spectral-resolution 2-micron spectroscopy of two FU Ori variables, V1057 Cyg and FU Ori, confirms that the ratio of IR-to-optical v sin i in these objects is significantly smaller than unity. The observed ratio is slightly larger than predictions of simple accretion-disk models but is consistent with strict Keplerian rotation given the uncertainties in the models. Blueshifted CO absorption is observed in FU Ori and in V1057 Cyg, suggesting mass loss at rates less than about 10 to the -7th solar mass/yr from the outer disk regions. The data suggest mass ejection in FU Ori is dominated by flows from inner disk regions. The mass-loss rate in FU Ori appears to be variable. 25 refs.

Kenyon, S.J.; Hartmann, L. (Harvard Smithsonian Center for Astrophysics, Cambridge, MA (USA))

1989-07-01

80

Mid-infrared Variability and Mass Accretion Toward NGC 2264 Protostars  

NASA Astrophysics Data System (ADS)

Variable mass accretion has been suggested to be an important aspect of protostar formation. Mid-infrared wavelength observations trace variations in accretion luminosity and thus can probe mass accretion on sub-AU scales. We present results from the Spitzer YSOVAR campaign towards class I protostars in NGC 2264. The precise (0.02 mag) several hour cadence light curves at 3.6 and 4.5 microns show that young star variability is ubiquitous, with a variety of morphologies and time scales. A structure function analysis shows the light curves, on average, have a power-law behavior up to 30 days. Moreover, the average structure function is the same for protostars in NGC 2264 and Orion. The power-law behavior suggests a stochastic process such as turbulent mass accretion. We discuss theoretical models and the prospects for determining mass accretion rates from synoptic studies.

Terebey, Susan; Cody, Ann Marie

2014-07-01

81

Quantifying decoherence in continuous variable systems  

E-print Network

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 purity, some nonclassicality indicators in phase space and, for two-mode states, entanglement measures and total correlations between the modes. Different sets of physically relevant initial configurations are considered, including one- and two-mode Gaussian states, number states, and coherent superpositions. Our analysis shows that, generally, the use of initially squeezed configurations does not help to preserve the coherence of Gaussian states, whereas it can be effective in protecting coherent superpositions of both number states and Gaussian wave packets.

Serafini, A; Illuminati, F; De Siena, S

2005-01-01

82

Quantifying decoherence in continuous variable systems  

E-print Network

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 purity, some nonclassicality indicators in phase space and, for two-mode states, entanglement measures and total correlations between the modes. Different sets of physically relevant initial configurations are considered, including one- and two-mode Gaussian states, number states, and coherent superpositions. Our analysis shows that, generally, the use of initially squeezed configurations does not help to preserve the coherence of Gaussian states, whereas it can be effective in protecting coherent superpositions of both number states and Gaussian wave packets.

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

2005-01-28

83

Twelfth IEEE Symposiumon Mass Storage Systems Optimizing Mass Storage Organizationand Access  

E-print Network

Twelfth IEEE Symposiumon Mass Storage Systems Optimizing Mass Storage Organizationand Access,Berkeley Berkeley, California Hanan Samet, Pedja Bogdanovich University of Maryland College Park, Maryland Abstract, in the context of a hierarchical mass storage system. Introduction Present day supercomputer simulations

Samet, Hanan

84

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.; Lajs, E. F.; He, J.-J.; Liao, W.-P.; Zhao, E.-G.; Liu, L.; Yang, Y.-G.

2014-08-01

85

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

86

Apparent mass of the human body in the vertical direction: Inter-subject variability  

NASA Astrophysics Data System (ADS)

The biodynamic responses of the seated human body to whole-body vibration vary considerably between people, but the reasons for the variability are not well understood. This study was designed to determine how the physical characteristics of people affect their apparent mass and whether inter-subject variability is influenced by the magnitude of vibration and the support of a seat backrest. The vertical apparent masses of 80 seated adults (41 males and 39 females aged 18-65) were measured at frequencies between 0.6 and 20 Hz with four backrest conditions (no backrest, upright rigid backrest, reclined rigid backrest, reclined foam backrest) and with three magnitudes of random vibration (0.5, 1.0 and 1.5 m s -2 rms). Relationships between subject physical characteristics (age, gender, weight, and anthropometry) and subject apparent mass were investigated with multiple regression models. The strongest predictor of the modulus of the vertical apparent mass at 0.6 Hz, at resonance, and at 12 Hz was body weight, with other factors having only a marginal effect. After correction for other variables, the principal resonance frequency was most consistently associated with age and body mass index. As age increased from 18 to 65 years, the resonance frequency increased by up to 1.7 Hz, and when the body mass index was increased from 18 to 34 kg m -2 the resonance frequency decreased by up to 1.7 Hz. These changes were greater than the 0.9-Hz increase in resonance frequency between sitting without a backrest and sitting with a reclined rigid backrest, and greater than the 1.0-Hz reduction in resonance frequency when the magnitude of vibration increased from 0.5 to 1.5 m s -2 rms. It is concluded that the effects of age, body mass index, posture, vibration magnitude, and weight should be taken into account when defining the vertical apparent mass of the seated human body.

Toward, Martin G. R.; Griffin, Michael J.

2011-02-01

87

The influence of mass-transfer variability on the growth of white dwarfs, and the implications for Type Ia supernova rates  

NASA Astrophysics Data System (ADS)

White dwarfs (WDs) can increase their mass by accretion from companion stars, provided the mass-accretion rate is high enough to avoid nova eruptions. The accretion regimes that allow growth of the WDs are usually calculated assuming constant mass-transfer rates. However, it is possible that these systems are influenced by effects that cause the rate to fluctuate on various time-scales. We investigate how long-term mass-transfer variability affects accreting WDs systems. We show that, if such variability is present, it expands the parameter space of binaries where the WD can effectively increase its mass. Furthermore, we find that the Type Ia supernova (SNIa) rate is enhanced by a factor 2-2.5 to a rate that is comparable with the lower limit of the observed rates. The changes in the delay-time distribution allow for more SNIae in stellar populations with ages of a few Gyr. Thus, mass-transfer variability gives rise to a new formation channel of SNIa events that can significantly contribute to the SNIa rate. Mass-transfer variability is also likely to affect other binary populations through enhanced WD growth. For example, it may explain why WDs in cataclysmic variables are observed to be more massive than single WDs, on average.

Toonen, S.; Voss, R.; Knigge, C.

2014-06-01

88

Neutral particle Mass Spectrometry with Nanomechanical Systems  

E-print Network

Current approaches to Mass Spectrometry (MS) necessarily rely on the ionization of the analytes of interest and subsequent spectrum interpretation is based on the mass-to-charge ratios of the ions. The resulting charge state distribution can be very complex for high-mass species which may hinder correct interpretation. A new form of MS analysis based on Nano-Electro-Mechanical Systems (NEMS) was recently demonstrated with high-mass ions. Thanks to a dedicated setup comprising both conventional time-of-flight MS (TOF-MS) and NEMS-MS in-situ, we show here for the first time that NEMS-MS analysis is insensitive to charge state: it provides one single peak regardless of the species charge state, highlighting effective clarification over existing MS analysis. All charged particles were thereafter removed from the beam electrostatically, and unlike TOF-MS, NEMS-MS retained its ability to perform mass measurements. This constitutes the first unequivocal measurement of mass spectra of neutral particles. This ability ...

Sage, Eric; Alava, Thomas; Morel, Robert; Dupr, Ccilia; Hanay, Mehmet Selim; Duraffourg, Laurent; Masselon, Christophe; Hentz, Sbastien

2014-01-01

89

Modeling systems with variability using the PROTEUS configuration language  

Microsoft Academic Search

Abstract. To respond to environmentalchanges,and customer specific requirements, industrial software systems must often incorporate many sources of variability. Developers use a diverse range of representatio ns and techniques to achieve this, including structural variability, component version selection, conditional inclusion, and varying derivation processes. This paper advocates specifying allpotential variability within a system using a single formalism. PCL, the configuration language

E. Tryggeseth; B. Gulla; R. Conradi

1985-01-01

90

Quality control technique to reduce the variability of longitudinal measurement of hemoglobin mass.  

PubMed

The sensitivity of the athlete blood passport to detect blood doping may be improved by the inclusion of total hemoglobin mass (Hb(mass)), but the comparability of Hb(mass) from different laboratories is unknown. To optimize detection sensitivity, the analytical variability associated with Hb(mass) measurement must be minimized. The aim of this study was to investigate the efficacy of using quality controls to minimize the variation in Hb(mass) between laboratories. Three simulated laboratories were set up in one location. Nine participants completed three carbon monoxide (CO) re-breathing tests in each laboratory. One participant completed two CO re-breathing tests in each laboratory. Simultaneously, quality controls containing Low (1-3%) and High (8-11%) concentrations of percent carboxyhemoglobin (%HbCO) were measured to compare hemoximeters in each laboratory. Linear mixed modeling was used to estimate the within-subject variation in Hb(mass), expressed as the coefficient of variation, and to estimate the effect of different laboratories. The analytic variation of Hb(mass) was 2.4% when tests were conducted in different laboratories, which reduced to 1.6% when the model accounted for between-laboratory differences. Adjustment of Hb(mass) values using quality controls achieved a comparable analytic variation of 1.7%. The majority of between-laboratory variation in Hb(mass) originated from the difference between hemoximeters, which could be eliminated using appropriate quality controls. PMID:21535184

Gough, C E; Sharpe, K; Ashenden, M J; Anson, J M; Saunders, P U; Garvican, L A; Bonetti, D L; Gore, C J; Prommer, N

2011-12-01

91

Mass Transit Living Lab: Improve the System  

NSDL National Science Digital Library

Students go through the process of identifying possible solutions to the design problems that the existing west corridor transit system faces. Students combine what they have learned from the three previous activities to come up with possible solutions to the design problems faced by the system. This activity requires the use of the Mass Transit Living Laba web portal to interactive train (transit) traffic data for a major metropolitan city.

Civil And Environmental Engineering Department

92

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

93

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

94

MASS ACTION IN THE NERVOUS SYSTEM WALTER J. FREEMAN  

E-print Network

MASS ACTION IN THE NERVOUS SYSTEM NW1 Library of Congress Cataloging in Publication Data Freeman, Walter J. Mass action IN THE UNITED STATES OF AMERICA #12; MASS ACTION IN THE NERVOUS SYSTEM Contents PREFACE

Freeman, Walter J.

95

Heart rate variability in systemic hypertension  

Microsoft Academic Search

Low heart rate (HR) variability is a risk factor for cardiac mortality in various patient populations, but it has not been well established whether patients with long-standing hypertension have abnormalities in the autonomic modulation of HR. Time and frequency domain measures of HR variability were compared in randomly selected, age-matched populations of 188 normotensive and 168 hypertensive males (mean age

Heikki V. Huikuri; Antti Ylitalo; Sirkku M. Pikkujms; Markku J. Ikheimo; K. E. Juhani Airaksinen; Asko O. Rantala; Mauno Lilja; Y. Antero Kesniemi

1996-01-01

96

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

97

Rotation and variability of very low mass stars and brown dwarfs near Epsilon Ori  

E-print Network

We explore the rotation and activity of very low mass (VLM) objects by means of a photometric variability study. Our targets in the vicinity of Epsilon Ori belong to the OriOB1b population in the Orion star-forming complex. In this region we selected 143 VLM stars and brown dwarfs (BDs), whose photometry in RIJHK is consistent with membership of the young population. The variability of these objects was investigated using a densely sampled I-band time series covering four consecutive nights with altogether 129 data points per object. Our targets show three types of variability: Thirty objects, including nine BDs, show significant photometric periods, ranging from 4h up to 100h, which we interpret as the rotation periods. Five objects, including two BDs, exhibit variability with high amplitudes up to 1 mag which is at least partly irregular. This behaviour is most likely caused by ongoing accretion and confirms that VLM objects undergo a T Tauri phase similar to solar-mass stars. Finally, one VLM star shows a strong flare event of 0.3 mag amplitude. The rotation periods show dependence on mass, i.e. the average period decreases with decreasing object mass, consistent with previously found mass-period relationships in younger and older clusters. The period distribution of BDs extends down to the breakup period, where centrifugal and gravitational forces are balanced. Combining our BD periods with literature data, we found that the lower period limit for substellar objects lies between 2h and 4h, more or less independent of age. Contrary to stars, these fast rotating BDs seem to evolve at constant rotation period from ages of 3 Myr to 1 Gyr, in spite of the contraction process. Thus, they should experience strong rotational braking.

Alexander Scholz; Jochen Eisloeffel

2004-10-05

98

Evolution of the orbital-plane orientations in the two-protoplanet three-body problem with variable masses  

NASA Astrophysics Data System (ADS)

The three body problem with variable masses with two of the bodies being protoplanets is analyzed. The protoplanetary masses are assumed to be much less than the protosolar mass: m 1( t) ? m 0( t), m 2( t) ? m 0( t). The variations of the body masses over time are assumed to be known. The masses vary isotropically with different rates: ? 0/ m 0? ? 1/ m 1, ? 0/ m 0? ? 2/ m 2, ? 1/ m 1? ? 2/ m 2. The bodies are treated like material points. The problem is described by analogy to the second system of Poincar elements, based on the equations of motion in a Jacobian coordinate system. Individual aperiodic motions in a quasi-conical cross section are used as the initial, unperturbed, intermediate motions. The expression for the perturbing function does not include terms proportional to third and higher powers of the small masses m 1 and m 2. A new analytical expression for the perturbing function analogous to the second system of the Poincar variables is obtained in the formulation considered using a classical scheme. The analogs of the eccentricities e 1 and e 2 and the orbital inclinations i 1 and i 2 are considered to be small. The perturbing function accurate to within terms of second order in the small quantities e 1, e 2, i 1, and i 2 is calculated in a symbolic form using Mathematica package. The equations for the secular perturbations in this protoplanetary three-body problem, with the bodies treated as points with masses varying isotropically with different rates, are obtained. General rigorous analytical solutions to these equations for the secular perturbations describing the evolution of the orbital planes are derived for oblique elements, for arbitrary mass-variation laws. An analog of the Laplace theorem is proved for the orbital inclinations. Analytical formulas are obtained for the temporal variation of the longitudes of the ascending nodes and the inclinations for arbitrary mass variations with different rates. It is shown that the Jacobian node theorem, which is valid in the classical three-body problem with constantmasses, is violated in this problem, unless special initial conditions apply.

Minglibayev, M. Zh.; Mayemerova, G. M.

2014-09-01

99

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

100

Planetary mass function and planetary systems  

NASA Astrophysics Data System (ADS)

With planets orbiting stars, a planetary mass function should not be seen as a low-mass extension of the stellar mass function, but a proper formalism needs to take care of the fact that the statistical properties of planet populations are linked to the properties of their respective host stars. This can be accounted for by describing planet populations by means of a differential planetary mass-radius-orbit function, which together with the fraction of stars with given properties that are orbited by planets and the stellar mass function allows the derivation of all statistics for any considered sample. These fundamental functions provide a framework for comparing statistics that result from different observing techniques and campaigns which all have their very specific selection procedures and detection efficiencies. Moreover, recent results both from gravitational microlensing campaigns and radial-velocity surveys of stars indicate that planets tend to cluster in systems rather than being the lonely child of their respective parent star. While planetary multiplicity in an observed system becomes obvious with the detection of several planets, its quantitative assessment however comes with the challenge to exclude the presence of further planets. Current exoplanet samples begin to give us first hints at the population statistics, whereas pictures of planet parameter space in its full complexity call for samples that are 2-4 orders of magnitude larger. In order to derive meaningful statistics, however, planet detection campaigns need to be designed in such a way that well-defined fully deterministic target selection, monitoring and detection criteria are applied. The probabilistic nature of gravitational microlensing makes this technique an illustrative example of all the encountered challenges and uncertainties.

Dominik, M.

2011-02-01

101

Large Scale Variability Survey of Orion II: mapping the young, low-mass stellar populations  

Microsoft Academic Search

We present further results of our ongoing large scale variability survey of the Orion OB1 Association, carried out with the 8k x 8k CCD Mosaic Camera on the 1m Schmidt telescope at the Venezuela National Observatory. In an area of over 60 square degrees we have unveiled new populations of low-mass young stars over a range of environments, from the

C. Briceo; N. Calvet; L. W. Hartmann; A. K. Vivas

2000-01-01

102

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

103

A mass conservative scheme for simulating shallow flows over variable topographies using unstructured grid  

NASA Astrophysics Data System (ADS)

Most available numerical methods face problems, in the presence of variable topographies, due to the imbalance between the source and flux terms. Treatments for this problem generally work well for structured grids, but most of them are not directly applicable for unstructured grids. On the other hand, despite of their good performance for discontinuous flows, most available numerical schemes (such as HLL flux and ENO schemes) induce a high level of numerical diffusion in simulating recirculating flows. A numerical method for simulating shallow recirculating flows over a variable topography on unstructured grids is presented. This mass conservative approach can simulate different flow conditions including recirculating, transcritical and discontinuous flows over variable topographies without upwinding of source terms and with a low level of numerical diffusion. Different numerical tests cases are presented to show the performance of the scheme for some challenging problems.

Mohamadian, A.; Le Roux, D. Y.; Tajrishi, M.; Mazaheri, K.

2005-05-01

104

VARIABLE RESOLUTION VISION SYSTEM IN MOBILE ROBOTICS  

Microsoft Academic Search

Onboard cameras are the main sensor in many mobile robots applications. High quality cameras require significant computing power to deal with large images. Real Time constraints further emphasize the need for fast and predictable image processing. Taking advantage of some known camera orientation parameters it is possible to reduce the number of interesting pixels by using variable resolution over the

Armando Sous; Antnio Moreira

2002-01-01

105

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

106

Modelling Systems with Variability using the PROTEUS Configuration Language  

Microsoft Academic Search

To respond to environmental changes and customer specific require- ments, industrial software systems must often incorporate many sources of vari- ability. Developers use a diverse range of representatio ns and techniques to achieve this, including structural variability, component version selection, condi- tional inclusion, and varying derivation processes. This paper advocates specifying all potential variability within a system using a single

Eirik Tryggeseth; Bjrn Gulla; Reidar Conradi

1995-01-01

107

Wind energy conversion system simulator using variable speed induction motor  

Microsoft Academic Search

The conventional synchronous generator in wind energy conversion system are now getting replaced by variable speed induction generator to extract maximum power with wide range of wind speed limit. The design and performance of such system are required a simplified digital simulator, especially for development of optimal control solutions. The proposed work is to make a prototype of an variable

S. W. Mohod; M. V. Aware

2010-01-01

108

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

E-print Network

Mechanism studies of seasonal variability of dissolved oxygen in Mass Bay: A multi-scale FVCOM Accepted 7 December 2013 Available online 14 December 2013 Keywords: Coastal Modeling Dissolved oxygen Mass that the dissolved oxygen (DO) concentration in Mass Bay exhibits a well-defined seasonal cycle, highest in March

Chen, Changsheng

109

Variability of water mass properties in the Strait of Sicily in summer period of 1998-2013  

NASA Astrophysics Data System (ADS)

The Strait of Sicily plays a crucial role in determining the water mass exchanges and related properties between western and eastern Mediterranean. The presence of sills to the east and west of the Strait of Sicily and the complex seabed topography modulate the thermohaline circulation of the Mediterranean basin. An anti-estuarine circulation is mainly characterized, from a dynamic point of view, by a two-layer system: a surface layer composed of Atlantic Water (AW) flowing eastward, essentially dominated by mesoscale processes, and a subsurface layer composed of Levantine Intermediate Water (LIW) flowing in the opposite direction; the topography appears to play an important role. Furthermore, there are transition water masses with variable hydrological characteristics. The dataset here studied is a time series 16 years long (1998-2013), which highlights the high horizontal and vertical interannual variability affecting the study area. Strong temperature-salinity correlations, in the intermediate layer, for specific time intervals, could be linked to the reversal of sub-surface circulation in the Central Ionian Sea. Moreover, a long-term monitoring of the hydrographic properties of water masses across this strait allow the modelers to assess the performance of hydrological models of this area.

Bonanno, A.; Placenti, F.; Basilone, G.; Mifsud, R.; Genovese, S.; Patti, B.; Di Bitetto, M.; Aronica, S.; Barra, M.; Giacalone, G.; Ferreri, R.; Fontana, I.; Buscaino, G.; Tranchida, G.; Quinci, E. M.; Mazzola, S.

2014-03-01

110

Measuring mixed cellulose ester (MCE) filter mass under variable humidity conditions.  

PubMed

Mixed cellulose ester (MCE) filters, used routinely to collect dust samples from air for fiber analysis, are the only filter type that can be prepared for both phased contrast microscopy and transmission electron microscopy analyses. However, whenever fiber counts require collecting dust masses <100 ?g on a single filter under variable relative humidity (RH) conditions, historically noted effects of humidity on MCE filter mass can hinder accurate estimates of dust mass, measured as loaded minus unloaded filter mass (M). In this study, a baseline set of hundreds of paired measures of change in RH versus M over different time intervals were obtained over a 5-day period for replicate series of 40 unloaded 37-mm MCE filters under varying RH conditions at a nearly constant temperature. Similar baseline data were obtained for 25-mm MCE filters. Linear regressions fit to these data allow improved estimates of dust mass loaded onto MCE filters from measures of M and RH made before and after loading occurs. Using established theory, these relationships were generalized to address temperature variation as well, and examples of numerical applications are provided. PMID:21430134

Bogen, Kenneth T; Brorby, Greg; Berman, D Wayne; Sheehan, Pat; Floyd, Mark

2011-06-01

111

Mass air flow engine control system with mass air event integrator  

Microsoft Academic Search

This patent describes a mass air flow metering system of the type responsive to the mass of air flowing into an internal combustion engine. It comprises: a mass air flow sensor providing an output signal V{sub {ital out}} responsive to mass air flow; an analog to digital converter connected to receive the output signal V{sub {ital out}} which produces a

H. E. Weissler; B. G. Shirley

1991-01-01

112

Surface Time-Variable Gravity Signals and Possible Sources Including Core Mass Flow  

NASA Technical Reports Server (NTRS)

Over two decades of geodetic satellite-laser-ranging (SLR) data show that the variation of the Earth's oblateness parameter J2 has a clear seasonal signal of amplitude of about 3e-10 and a secular decrease of about -2.8e-11/year, superimposed on some interesting interannual fluctuations. Physically, any change in mass distribution or/inside the Earth will be reflected in the time-variable gravity signal obtained outside the Earth, according to Newton s gravitational law. Therefore, such signal contains contributions from all geophysical sources that redistribute mass, on all temporal and spatial scales, including those from the core. Besides Earth rotation and geomagnetic field variations, the time-variable gravity also contains information linking Earth surface observations with internal core dynamical processes. The time scales of the gravity signal are critical in helping differentiate different contributions. The atmosphere and hydrosphere are responsible for the seasonal and much of the interannual and intraseasoanl fluctuations, while the secular trend is due mainly to the post-glacial rebound but possibly core mass flow. To estimate the latter effect, we use our MoSST (Modular, Scalable, Self-consistent, Three-dimensional) core dynamics model to forward simulate the core flow, and density variation due to the core convection. Our results suggest that, when upward continued to the surface, the J2 component of the core mass redistribution can reach an overall amplitude of e-11/year, approaching the SLR detectability and significant in geophysical terms. We also find a general westward drift of the mass flow, with a speed comparable to that of the geomagnetic westward drift.

Chao, Benjamin F.; Kuang, Weijia

2003-01-01

113

Re-interpreting the Oxbridge stransverse mass variable M T2 in general cases  

NASA Astrophysics Data System (ADS)

We extend the range of possible applications of M T2 type analyses to decay chains with multiple invisible particles, as well as to asymmetric event topologies with different parent and/or different children particles. We advocate two possible approaches. In the first, we introduce suitably defined 3 + 1-dimensional analogues of the M T2 variable, which take into account all relevant on-shell kinematic constraints in a given event topology. The second approach utilizes the conventional M T2 variable, but its kinematic endpoint is suitably reinterpreted on a case by case basis, depending on the specific event topology at hand. We provide the general prescription for this reinterpretation, including the formulas relating the measured M T2 endpoint (as a function of the test masses of all the invisible particles) to the underlying physical mass spectrum. We also provide analytical formulas for the shape of the differential distribution of the doubly projected {M_{{T{2_{bot }}}}} variable for the ten possible event topologies with one visible particle and up to two invisible particles per decay chain. We illustrate our results with the example of leptonic chargino decays {{widetilde{?}}+}to {ell+}? {{widetilde{?}}^0} in supersymmetry.

Mahbubani, Rakhi; Matchev, Konstantin T.; Park, Myeonghun

2013-03-01

114

On-shell constrained M 2 variables with applications to mass measurements and topology disambiguation  

NASA Astrophysics Data System (ADS)

We consider a class of on-shell constrained mass variables that are 3+1 dimensional generalizations of the Cambridge M T2 variable and that automatically incorporate various assumptions about the underlying event topology. The presence of additional on-shell constraints causes their kinematic distributions to exhibit sharper endpoints than the usual M T2 distribution. We study the mathematical properties of these new variables, e.g., the uniqueness of the solution selected by the minimization over the invisible particle 4-momenta. We then use this solution to reconstruct the masses of various particles along the decay chain. We propose several tests for validating the assumed event topology in missing energy events from new physics. The tests are able to determine: 1) whether the decays in the event are two-body or three-body, 2) if the decay is two-body, whether the intermediate resonances in the two decay chains are the same, and 3) the exact sequence in which the visible particles are emitted from each decay chain.

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

2014-08-01

115

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

116

Sudden loss of mass from a binary gravitating system  

NASA Astrophysics Data System (ADS)

Mitalas's (1980) study is generalized to treat sudden mass loss from a binary syste in an originally elliptical orbit. The orbits are characterized by angular momentum and energy, and it is shown that none of the changes in the relative orbit depends on which object it is that loses part of its mass. It is pointed out that, in principle, each could lose a different fraction. Time averages are introduced so that the orbital changes, which depend on where in orbit the mass loss takes place, can be suitably averaged over a statistical ensemble of initial systems. Even though many results that appear to be new are presented, it is noted that the main thrust is to choose and manipulate variables yielding the greatest economy of description and the greatest power of computation. Graphs are included showing the fraction of systems that on the average will be disrupted, the mean orbital changes for the survivors, and the extreme limits for the change in eccentricity.

Noerdlinger, P. D.

1982-08-01

117

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.

Cho, Won Sang; Kim, Doojin; Matchev, Konstantin T; Moortgat, Filip; Pape, Luc; Park, Myeonghun

2014-01-01

118

Bubble mass center and fluid feedback force fluctuations activated by constant lateral impulse with variable thrust  

NASA Technical Reports Server (NTRS)

Sloshing dynamics within a partially filled rotating dewar of superfluid helium 2 are investigated in response to constant lateral impulse with variable thrust. The study, including how the rotating bubble of superfluid helium 2 reacts to the constant impulse with variable time period of thrust action in microgravity, how amplitudes of bubble mass center fluctuates with growth and decay of disturbances, and how fluid feedback forces fluctuates in activating on the rotating dewar through the dynamics of sloshing waves are investigated. The numerical computation of sloshing dynamics is based on the non-inertial frame spacecraft bound coordinate with lateral impulses actuating on the rotating dewar in both inertial and non-inertial frames of thrust. Results of the simulations are illustrated.

Hung, R. J.; Long, Y. T.

1995-01-01

119

Variables Affecting Two Electron Transport System Assays  

PubMed Central

Several methodological variables were critical in two commonly used electron transport activity assays. The dehydrogenase assay based on triphenyl formazan production exhibited a nonlinear relationship between formazan production (dehydrogenase activity) and sediment dilution, and linear formazan production occurred for 1 h in sediment slurries. Activity decreased with increased time of sediment storage at 4C. Extraction efficiencies of formazan from sediment varied with alcohol type; methanol was unsatisfactory. Phosphate buffer (0.06 M) produced higher activity than did either U.S. Environmental Protection Agency reconstituted hard water or Tris buffer sediment diluents. Intracellular formazan crystals were dissolved within minutes when in contact with immersion oil. Greater crystal production (respiration) detected by a tetrazolium salt assay occurred at increased substrate concentrations. Test diluents containing macrophyte exudates produced greater activity than did phosphate buffer, U.S. Environmental Protection Agency water, or ultrapure water diluents. Both assays showed decreases in sediment or bacterial activity through time. PMID:16347067

Burton, G. Allen; Lanza, Guy R.

1986-01-01

120

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

121

Southern Hemisphere water mass conversion linked with North Atlantic climate variability.  

PubMed

Intermediate water variability at multicentennial scales is documented by 340,000-year-long isotope time series from bottom-dwelling foraminifers at a mid-depth core site in the southwest Pacific. Periods of sudden increases in intermediate water production are linked with transient Southern Hemisphere warm episodes, which implies direct control of climate warming on intermediate water conversion at high southern latitudes. Coincidence with episodes of climate cooling and minimum or halted deepwater convection in the North Atlantic provides striking evidence for interdependence of water mass conversion in both hemispheres, with implications for interhemispheric forcing of ocean thermohaline circulation and climate instability. PMID:15774752

Pahnke, Katharina; Zahn, Rainer

2005-03-18

122

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-Pyrnes 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-Len 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, Luca; Merino, Andrs; Snchez, Jos Luis; Berthet, Claude; Dessens, Jean; Lpez, Laura; Fernndez-Gonzlez, Sergio; Gascn, Estbaliz; Garca-Ortega, Eduardo

2014-05-01

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

Variability in Second Language Development from a Dynamic Systems Perspective  

ERIC Educational Resources Information Center

This article illustrates that studying intra-individual variability in Second Language Development can provide insight into the developmental dynamics of second language (L2) learners. Adopting a Dynamic Systems Theory framework (Thelen & Smith, 1994; van Geert, 1994) and using insights from microgenetic variability studies in developmental

Verspoor, Marjolijn; Lowie, Wander; Van Dijk, Marijn

2008-01-01

125

Energy efficient ECS powered by a variable voltage\\/variable frequency power system  

Microsoft Academic Search

The invention is an ECS system designed to utilize an induction motor and a cabin compressor for providing pressurized air that serves as a source of energy for heating, cooling, pressurizing and other air needs of modern aircraft. An aircraft engine driven generator, preferably a permanent-magnet generator (of the samarium-cobalt, SmCo, type), furnishes variable-voltage\\/variable frequency, VV\\/VF, power to the motor.

Cronin

1984-01-01

126

Energy efficient ECS powered by a variable voltage\\/variable frequency power system  

Microsoft Academic Search

The invention is an ECS system designed to utilize an induction motor and a cabin compressor for providing pressurized air that serves as a source of energy for heating, cooling, pressurizing and other air needs of modern aircraft. An aircraft engine driven generator, preferably a permanent-magnet generator (of the samarium-cobalt, SmCo, type), furnishes variable-voltage\\/variable frequency, VV\\/VF, power to the motor.

Cronin

1985-01-01

127

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

128

Optical variability of the low-mass, X-ray binary 1556-605  

NASA Astrophysics Data System (ADS)

BVRI photometry of the low-mass, X-ray binary 1556-605, obtained during five nights in June 1988, failed to identify an underlying orbital period. Nightly variations of 0.3 magnitude in V were present, but the colors of the system remained constant.

Schmidtke, Paul C.

1990-02-01

129

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.

130

Intelligent design systems for apparel mass customization  

Microsoft Academic Search

To deal with the challenges of shortened product life cycle while considering various trends and consumers demands, several companies have begun to explore mass customization. In this paper, we study the economic factors leading to mass customization, review the advanced technologies and develop a new process of computer?aided design (CAD) for effective mass customization. To define the purchasing patterns of

Dnyanada Satam; Yan Liu; Hoon Joo Lee

2011-01-01

131

Practical robust control of robot arm using variable structure system  

Microsoft Academic Search

The high-gain effect of sliding mode control based on VSS (Variable Structure System) suppresses the uncertainties due to parametric variations, external disturbances and variable payloads. The resulting system is completely robust whereas the obtained control law is simple and easy to be applied to on-line computer control. In this paper, the sliding mode controller for MIMO (Multi-Input Multi-Output) robot arm

F. Harashima; H. Hashimoto; K. Maruyama

1986-01-01

132

Variability in the 2MASS calibration fields: a search for transient obscuration events  

NASA Astrophysics Data System (ADS)

We searched the light curves of over 40 000 stars in the Two Micron All Sky Survey (2MASS) calibration data base, spanning approximately 4 yr, for objects that have significant day-long dimming events. We also searched the multi-colour light curves for red-dimming events that could be due to transient extinction. In the colour-independent sigma-limited search, we found 46 previously unrecognized eclipsing binaries, 6 previously unrecognized periodic variable stars likely to be intrinsic pulsators and 21 young stellar objects in the ? Ophiuchus star formation region previously studied by Parks et al. An additional 11 objects exhibited dimming events, and most of these are unclassified. The search for red-dimming events primarily reveals a population of low-luminosity active galaxies that become bluer when they are brighter, and variable young stellar objects exhibiting high cross-correlation coefficients between colour and brightness. The young stellar objects primarily exhibit brightness and colour variations in the direction of interstellar extinction whereas the active galaxies can have a bowed distribution in colour and magnitude with reduced variation in colour when the object is brightest. Among the objects that are usually quiescent (not strongly variable), we failed to find any dimming events deeper than 0.2 mag and lasting longer than a day. Two of the young stellar objects, however, dimmed by 0.2 mag for longer than a day without strong colour variation.

Quillen, Alice C.; Ciocca, Marco; Carlin, Jeffrey L.; Bell, Cameron P. M.; Meng, Zeyang

2014-07-01

133

Variable-Speed Wind System Design : Final Report.  

SciTech Connect

Almost from the onset of the development of wind energy conversion systems (WECS), it was known that variable-speed operation of the turbine would maximize energy capture. This study was commissioned to assess the cost, efficiency gain, reduction of the cost of energy (COE), and other operating implications of converting the existing hardware of a modern fixed-speed wind energy conversion system to variable-speed operation. The purpose of this study was to develop a preliminary design for the hardware required to allow variable-speed operation using a doubly-fed generator with an existing fixed-speed wind turbine design. The turbine selected for this study is the AWT-26 designed and built by Advanced Wind Turbines Inc. of Redmond, Washington. The lowest projected COE using this variable-speed generation system is projected to be $0.0499/kWh, compared to the lowest possible COE with fixed-speed generation which is projected to be $0.0546/kWh. This translates into a 8.6% reduction of the COE using this variable-speed generation option. The preliminary system design has advanced to where the printed circuit boards can be physically laid out based on the schematics and the system software can be written based on the control flow-charts. The core of hardware and software has been proven to be successful in earlier versions of VSG systems. The body of this report presents the results of the VSWG system development. Operation under normal and fault conditions is described in detail, the system performance for variable-speed operation is estimated and compared to the original fixed-speed system performance, and specifications for all system components (generator, power electronic converter, and system controller) are given. Costs for all components are estimated, and incremental system cost is compared to incremental energy production. Finally, operational features of the VSWG which are not available in the existing FSWG system are outlined.

Lauw, Hinan K.; Weigand, Claus H.; Marckx, Dallas A.; Electronic Power Conditioning, Inc.

1993-10-01

134

Features of the mass transfer in magnetic cataclysmic variables with fast-rotating white dwarfs  

NASA Astrophysics Data System (ADS)

The flow structure in magnetic cataclysmic variables was investigated taking into account the effects of strong magnetic field and fast rotation of the white dwarf. We modeled the AE Aqr system as a unique object that has the rotation period of the white dwarf is about 1000 times shorter than the orbital period of the binary system. Observations show that in spite of fast rotation of the white dwarf some part of the stream from the inner Lagrange point comes into the Roche lobe region. We analyzed possible mechanisms preventing material to outflow from the system.

Isakova, Polina; Zhilkin, Andrey; Bisikalo, Dmitry

2014-01-01

135

Secular Dynamics in Hierarchical Three-body Systems with Mass Loss and Mass Transfer  

NASA Astrophysics Data System (ADS)

Recent studies have shown that secular evolution of triple systems can play a major role in the evolution and interaction of their inner binaries. Very few studies explored the stellar evolution of triple systems, and in particular the mass-loss phase of the evolving stellar components. Here we study the dynamical secular evolution of hierarchical triple systems undergoing mass loss. We use the secular evolution equations and include the effects of mass loss and mass transfer, as well as general relativistic effects. We present various evolutionary channels taking place in such evolving triples, and discuss both the effects of mass loss and mass transfer in the inner binary system, as well as the effects of mass loss/transfer from an outer third companion. We discuss several distinct types/regimes of triple secular evolution, where the specific behavior of a triple system can sensitively depend on its hierarchy and the relative importance of classical and general relativistic effects. We show that the orbital changes due to mass-loss and/or mass-transfer processes can effectively transfer a triple system from one dynamical regime to another. In particular, mass loss/transfer can both induce and quench high-amplitude (Lidov-Kozai) variations in the eccentricity and inclination of the inner binaries of evolving triples. They can also change the system dynamics from an orderly periodic behavior to a chaotic one, and vice versa.

Michaely, Erez; Perets, Hagai B.

2014-10-01

136

Global Variability of Mesoscale Convective System  

NASA Technical Reports Server (NTRS)

Mesoscale convective systems (MCSs) in the tropics produce extensive anvil clouds, which significantly affect the transfer of radiation. This study develops an objective method to identify MCSs and their anvils by combining data from three A-train satellite instruments: Moderate Resolution Imaging Spectroradiometer (MODIS) for cloud-top size and coldness, Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) for rain area size and intensity, and CloudSat for horizontal and vertical dimensions of anvils. The authors distinguish three types of MCSs: small and large separated MCSs and connected MCSs. The latter are MCSs sharing a contiguous rain area. Mapping of the objectively identified MCSs shows patterns of MCSs that are consistent with previous studies of tropical convection, with separated MCSs dominant over Africa and the Amazon regions and connected MCSs favored over the warm pool of the Indian and west Pacific Oceans. By separating the anvil from the raining regions of MCSs, this study leads to quantitative global maps of anvil coverage. These maps are consistent with the MCS analysis, and they lay the foundation for estimating the global radiative effects of anvil clouds. CloudSat radar data show that the modal thickness of MCS anvils is about 4--5 km. Anvils are mostly confined to within 1.5--2 times the equivalent radii of the primary rain areas of the MCSs. Over the warm pool, they may extend out to about 5 times the rain area radii. The warm ocean MCSs tend to have thicker non-raining and lightly raining anvils near the edges of their actively raining regions, indicating that anvils are generated in and spread out from the primary raining regions of the MCSs. Thicker anvils are nearly absent over continental regions.

Yuan, J.; Houze, R. A., Jr.

2010-01-01

137

Seasonal variability of water masses and transport on the Antarctic continental shelf and slope in the southeastern Weddell Sea  

E-print Network

Seasonal variability of water masses and transport on the Antarctic continental shelf and slope of water masses and transport on the Antarctic continental shelf and slope in the southeastern Weddell Sea transport of cold, fresh surface waters onto the continental shelf. Offshore, the warmer, saltier Warm Deep

138

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

139

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, Jrgen; Klemann, Volker; Sneeuw, Nico

2014-11-01

140

Variability of Mass Dependence of Auroral Acceleration Processes with Solar Activity  

NASA Technical Reports Server (NTRS)

The objectives of this investigation are to improve understanding of the mass dependent variability of the auroral acceleration processes and so to clarify apparent discrepancies regarding the altitude and local time variations with solar cycle by investigating: (1) the global morphological relationships between auroral electric field structures and the related particle signatures under varying conditions of solar activity, and (2) the relationships between the electric field structures and particle signatures in selected events that are representative of the different conditions occurring during a solar cycle. The investigation is based in part on the Lockheed UFI data base of UpFlowing Ion (UFI) events in the 5OO eV to 16keV energy range and associated electrons in the energy range 7O eV to 24 keV. This data base was constructed from data acquired by the ion mass spectrometer on the S3-3 satellite in the altitude range of I to 1.3 Re. The launch of the POLAR spacecraft in early 1996 and successful operation of its TIMAS ion mass spectrometer has provided us with data from within the auroral acceleration regions during the current solar minimum. The perigee of POLAR is at about 1 Re, comparable to that of S3-3. The higher sensitivity and time resolution of TIMAS compared to the ion mass spectrometer on S3-3 together with its wider energy range, 15 eV to 33 keV, facilitate more detailed studies of upflowing ions.

Ghielmetti, Arthur G.

1997-01-01

141

Mesoscale variability of water masses in the Arabian Sea as revealed by ARGO floats  

NASA Astrophysics Data System (ADS)

By analysing ARGO float data over the last four years, some aspects of the mesoscale variability of water masses in the Arabian Sea are described. The Red Sea Water outflow is strong in the Southwestern Gulf of Aden, in particular when a cyclonic gyre predominates in this region. Salinities of 36.5 and temperatures of 16 C are found there between 600 and 1000 m depths. The Red Sea Water is more dilute in the eastern part of the Gulf, and fragments of this water mass can be advected offshore across the gulf or towards its northern coast by the regional gyres. The Red Sea Water outflow is also detected along the northeastern coast of Socotra, and fragments of RSW are found between one and three degrees of latitude north of this island. In the whole Gulf of Aden, the correlation between the deep motions of the floats and the SSH measured by altimetry is strong, at regional scale. The finer scale details of the float trajectories are more often related to the anomalous water masses that they encounter. The Persian Gulf Water (PGW) is found in the float profiles near Ras ash Sharbatat (near 57 E, 18 N), again with 36.5 in salinity and about 18-19 C in temperature. These observations were achieved in winter when the southwestward monsoon currents can advect PGW along the South Arabian coast. Fragments of PGW are found in the Arabian Sea between 18 and 20 N and 63 and 65 E, showing that this water mass can escape the Gulf of Oman southeastward, in particular during summer.

Carton, X.; L'Hegaret, P.

2011-06-01

142

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

143

Signs of Lorentz violation in electrodynamics: variable speed of light and the photon mass  

E-print Network

Recent studies of spacetime anisotropy in the context of local Lorentz invariance (LLI) based on classical Michelson-Morley experiments, as well Kennedy-Thorndyke tests, pointed out the existence of terms first order in v/c and of angular signatures independent of v. This contribution replaces the Lorentz symmetry by a velocity gauge transformation following an argument centred on observability. Results show even and odd order terms and indicate that motion is always underestimated in the spatiotemporal platform. Though LLI is not recovered in exact special relativistic terms, the alternative looks compatible with the relational aspects of general relativity (GR) with variable speed of light models as well a nonzero photon mass. This raises the hypothesis that Einstein equivalence principle, and consequently LLI, is a cornerstone of GR, but not necessarily a fundamental one of SR

R. Assumpcao

2003-05-09

144

Assesssing Variability of Dusty Galactic and Magellanic WRs and Seeking MIR Mass-Loss Nebulae  

NASA Astrophysics Data System (ADS)

Wolf-Rayet (WR) stars are rare high-mass stars with potent winds which disturb and chemically enrich their surroundings, often creating optical nebulae as their ejecta sweep up the local interstellar medium. The intriguing dusty late-type carbon WRs) have generated thick circumstellar shells. Many WCs often have variable dust production, some periodic, others random. Only by studying all these highly energetic stars in depth will we decipher the nature of the dust condensation process and the pathway to grains in these hydrogen-poor atmospheres. This promises an accurate assessment of the quantitative contribution of WRs to the cosmic carbon budget. Such stars are few in number, but play a key role in generating the chemical elements and recycling stellar material. In 2001 we knew 227 Galactic WRs and 99% of the WC9s were dusty. Today we list close to 400 WR including the the WN and WO types. But only 56% of the WC9s are known to be dusty, dominated by those with persistent dust. Those for which we have determined both the existence of dust variability and know its temporal character is still of order 10. Much work remains to characterize the nature and variability of IR emission for many newly discovered WCs which have only optical classifications. Every new IR survey of the Galactic plane has the potential to offer crucial data on dusty WR stars, by finding new examples or providing another epoch of photometry for previously known WCs, to compare with earlier IR data to study the individual mass loss history for each. This is the method by which these variable stars were found to undergo episodes of dust making and it maximizes the value of old data sets, particularly when the effort is made to maintain a consistent absolute calibration for new missions. It is not enough merely to uncover new WCs, nor even to assign spectral classes to them. It is also essential to archive their spectral energy distributions (SEDs) as fiducial references for the future. Spitzer offers a wealth of new measurements of known WRs and it has already contributed substantially to the increase in the current census of Galactic WRs. WRs are often associated with optical so-called "ring nebulae" which are essentially fossil records of stellar mass loss. Spitzer has observed, and is currently still observing, large areas of the Galactic plane. It is timely to undertake an unbiased survey of WRs looking for new, small, faint 5-20 micron counterparts, particularly for the WC and WO stars which,combined, are a factor of two less frequently allied with ring nebulae than are WN stars. My specific objectives are to: (i) develop IR SEDs for as many as possible of the known WR stars in the Galaxy and in the Magellanic Clouds; (ii) quantify any IR excess over the combination of photosphere, wind, and free-free emission; (iii) determine whether each excess is due to free-free or thermal emission of warm dust grains and, for dust, measure the temperature; (iv) decide from all available IR photometry of a WC star at different epochs whether this dust emission is variable or constant; (v) create a repository of reference SEDs of all dusty WC stars, in particular, so that future observations may be compared with these benchmarks; (vi) seek new dusty WRs in those regions of the Galactic plane that are still being surveyed by Spitzer; (vii) examine Spitzer images of all known Galactic and Magellanic WRs seeking unknown, potentially associated, MIR nebulae; (viii) measure spatially integrated nebular SEDs; (ix) test whether these nebulae are thermal radio emitters and, if so, determine their IRAC/MIPS color indices, false colors and MIR/radio flux ratios as potential discriminants for WR nebulae among the many kinds of bubble in the ISM.

Cohen, Martin

145

On the relationship between the water mass pathways and eddy variability in the Western Mediterranean Sea  

NASA Astrophysics Data System (ADS)

The role of eddies on the formation and spreading of water masses in the Western Mediterranean Sea is studied with an ocean general circulation model. The model is forced with interannually variable surface forcing for the years from 1979 to 1999. It is found that the model reproduces the major features of the observed mesoscale variability in the Gulf of Lions and the large eddies evolution in the Algerian Basin. The seasonal evolution of circulation in the Gulf of Lions and processes of spreading of newly formed intermediate deep waters in the postconvection period is studied for years 1987 and 1992. The model results are compared with data from observations. It is shown that the instability of the transition zone between old and newly formed deep waters, which takes place after the violent mixing stages of the deep convection, leads to collapse of the mixed patch and formation of mesoscale eddies. Some of these eddies propagate out of the Gulf of Lions transporting deep waters into the Algerian Basin. The rest of the mesoscale eddies filled with newly formed deep waters remain in the Gulf of Lions and tend to merge and enlarge. After the cyclonic eddies reach the Algerian Basin they interact with the intense mesoscale field existing there. The energy analysis shows that the winter and spring are seasons of intensified baroclinic instability of the mean flow in the two regions of interest, the Gulf of Lions and Algerian Basin. The kinetic energy is released by baroclinic instability in spring and summer. The spring spectra in the two regions have maximums at horizontal scales of about 80-100 km which is the typical scale of the eddies in the model. These eddies propagate a cyclonic circuit. The resulting eddy-induced mass transport in deep and intermediate layers is directed out of the Gulf of Lions and toward the Gibraltar Strait. Equivalently, we can argue the intermediate and deep waters conveyor belt of the Western Mediterranean Sea is eddy-driven.

Demirov, E. K.; Pinardi, N.

2007-02-01

146

Factorial Experimental Designs Elucidate Significant Variables Affecting Data Acquisition on a Quadrupole Orbitrap Mass Spectrometer  

NASA Astrophysics Data System (ADS)

Instrument parameter values for a quadrupole Orbitrap mass spectrometer were optimized for performing global proteomic analyses. Fourteen factors were evaluated for their influence on data-dependent acquisition with an emphasis on both the rate of sequencing and spectral quality by maximizing two individually tested response variables (unique peptides and protein groups). Of the 14 factors, 12 factors were assigned significant contrast values ( P < 0.05) for both response variables. Fundamentally, when optimizing parameters, a balance between spectral quality and duty cycle needs to be reached in order to maximize proteome coverage. This is especially true when using a data-dependent approach for sequencing complex proteomes. For example, maximum ion injection time, automatic gain control settings, and minimum threshold settings for triggering MS/MS isolation and activation all heavily influence ion signal, the number of spectra collected, and spectral quality. To better assess the effect these parameters have on data acquisition, all MS/MS data were parsed according to ion abundance by calculating the percent of the AGC target reached for each MS/MS event and then compared with successful peptide-spectrum matches. This proved to be an effective approach for understanding the effect of ion abundance on successful peptide-spectrum matches and establishing minimum ion abundance thresholds for triggering MS/MS isolation and activation.

Randall, Shan M.; Cardasis, Helene L.; Muddiman, David C.

2013-10-01

147

Vital role of daily temperature variability in surface mass balance parameterizations of the Greenland Ice Sheet  

NASA Astrophysics Data System (ADS)

This study aims to demonstrate that the spatial and seasonal effects of daily temperature variability in positive degree-day (PDD) models play a decisive role in shaping the modeled surface mass balance (SMB) of continental-scale ice masses. Here we derive monthly fields of daily temperature standard deviation (SD) across Greenland from the ERA-40 (European Centre for Medium-Range Weather Forecasts 40 yr Reanalysis) reanalysis spanning from 1958 to 2001 and apply these fields to model recent surface responses of the Greenland Ice Sheet (GIS). Neither the climate data set analyzed nor in situ measurements taken in Greenland support the range of commonly used spatially and temporally uniform SD values (~ 5 C). In this region, the SD distribution is highly inhomogeneous and characterized by low values during summer months (~ 1 to 2.5 C) in areas where most surface melting occurs. As a result, existing SMB parameterizations using uniform, high SD values fail to capture both the spatial pattern and amplitude of the observed surface responses of the GIS. Using realistic SD values enables significant improvements in the modeled regional and total SMB with respect to existing estimates from recent satellite observations and the results of a high-resolution regional model. In addition, this resolves large uncertainties associated with other major parameters of a PDD model, namely degree-day factors. The model appears to be nearly insensitive to the choice of degree-day factors after adopting the realistic SD distribution.

Rogozhina, I.; Rau, D.

2014-04-01

148

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

149

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

NASA Technical Reports Server (NTRS)

Cox and Chao [2002] reported the detection of a large anomaly in the form of a positive "jump" in the time series of Earth's lowest-degree gravity harmonic J2, or the dynamic oblateness, during 1998. This prompted us to examine the mass redistribution in the global oceans. We report here a seesaw of the sea-surface height (SSH) in the extratropic north + south Pacific basins -- the leading (nonseasonal) EOF/PC mode in SSH derived from the 10-year TOPEX/Poseidon altimetry data in the extratropic Pacific region. The mode underwent a step-like jump with time evolution that match remarkably well with the observed J2 anomaly. However, the magnitude is several times too small to explain the observed J2, even if assuming the SSH jump was all mass-induced (as opposed to any steric effect which causes no time-variable gravity signal). If one accepts the notion that this extratropic Pacific seesaw is part of the geophysical process that produced the observed 1998 J2 anomaly, then this finding suggests strong geophysical connection of the interannual-to-decadal variation of J2 with the Pacific Decadal Oscillation (PDO), as the time series of the above EOF/PC mode is actually a formally defined PDO Index series.

Chao, Benjamin F.; Au, A. Y.; Cox, C. M.

2002-01-01

150

Mesoscale variability of water masses in the Arabian Sea as revealed by ARGO floats  

NASA Astrophysics Data System (ADS)

By analysing ARGO float data over the last four years, a few aspects of the mesoscale variability of water masses in the Arabian Sea are described. The Red Sea Outflow Water (RSOW) is concentrated in the Southwestern Gulf of Aden, in particular when a cyclonic gyre predominates in this region. Salinities of 36.5 and temperatures of 16 C are found in this area at depths between 600 and 1000 m. RSOW is more dilute in the eastern part of the Gulf, where intense and relatively barotropic gyres mix it with Indian ocean Central Water. RSOW is also detected along the northeastern coast of Socotra, and fragments of RSOW are found between one and three degrees of latitude north of this island. In the whole Gulf of Aden, the correlation between the deep motions of the floats and the sea-level anomaly measured by altimetry is strong, at regional scale. The finer scale details of the float trajectories are not sampled by altimetry and are often related to the anomalous water masses that the floats encounter. The Persian Gulf Water (PGW) is found in the float profiles near Ras ash Sharbatat (near 57 E, 18 N), again with 36.5 in salinity and about 18-19 C in temperature. These observations were achieved in winter when the southwestward monsoon currents can advect PGW along the South Arabian coast. Fragments of PGW were also observed in the Arabian Sea between 18 and 20 N and 63 and 65 E in summer, showing that this water mass can escape the Gulf of Oman southeastward, during that season. Kinetic energy distributions of floats with respect to distance or angle share common features between the two regions (Gulf of Aden and Arabian Sea), in particular peaks at 30, 50 and 150 km scales and along the axis of monsoon currents. Hydrological measurements by floats are also influenced by the seasonal variations of PGW and RSOW in these regions.

Carton, X.; L'Hegaret, P.; Baraille, R.

2012-03-01

151

Local entanglement of multidimensional continuous-variable systems  

E-print Network

We study the `local entanglement' remaining after filtering operations corresponding to imperfect measurements performed by one or both parties, such that the parties can only determine whether or not the system is located in some region of space. The local entanglement in pure states of general bipartite multidimensional continuous-variable systems can be completely determined through simple expressions. We apply our approach to semiclassical WKB systems, multi-dimensional harmonic oscillators, and a hydrogen atom as three examples.

H. -C. Lin; A. J. Fisher

2007-11-23

152

2MASS J01542930+0053266 : A New Eclipsing M-dwarf Binary System  

E-print Network

We report on 2MASS J01542930+0053266, a faint eclipsing system composed of two M dwarfs. The variability of this system was originally discovered during a pilot study of the 2MASS Calibration Point Source Working Database. Additional photometry from the Sloan Digital Sky Survey yields an 8-passband lightcurve, from which we derive an orbital period of 2.6390157 +/- 0.0000016 days. Spectroscopic followup confirms our photometric classification of the system, which is likely composed of M0 and M1 dwarfs. Radial velocity measurements allow us to derive the masses (M_1 = 0.66 +/- 0.03 M_sun; M_2 = 0.62 +/- 0.03 M_sun) and radii (R_1 = 0.64 +/- 0.08 R_sun; R_2 = 0.61 +/- 0.09 R_sun) of the components, which are consistent with empirical mass-radius relationships for low-mass stars in binary systems. We perform Monte Carlo simulations of the lightcurves which allow us to uncover complicated degeneracies between the system parameters. Both stars show evidence of H-alpha emission, something not common in early-type M dwarfs. This suggests that binarity may influence the magnetic activity properties of low-mass stars; activity in the binary may persist long after the dynamos in their isolated counterparts have decayed, yielding a new potential foreground of flaring activity for next generation variability surveys.

A. C. Becker; E. Agol; N. M. Silvestri; J. J. Bochanski; C. Laws; A. A. West; G. Basri; V. Belokurov; D. M. Bramich; J. M. Carpenter; P. Challis; K. R. Covey; R. M. Cutri; N. W. Evans; M. Fellhauer; A. Garg; G. Gilmore; P. Hewett; P. Plavchan; D. P. Schneider; C. L. Slesnick; S. Vidrih; L. M. Walkowicz; D. B. Zucker

2008-01-29

153

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.

Seward, Kim; Puckett, Jennifer

2008-01-01

154

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+1.00106 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

Giacch, S.; Gilli, R.; Titarchuk, L.

2014-02-01

155

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

156

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

2008-02-08

157

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.

158

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

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

A coarsegrained model of evolution with variable system size  

E-print Network

with the analysis of the fossil record performed by Raup. For his model he found an exponent of the power­law close to 2, which is in good agreement with the fossil record. Thus Newman came to the conclusionA coarse­grained model of evolution with variable system size C. Wilke und T. Martinetz Institut f

161

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

162

Evaluation of a variable dose acquisition technique for microcalcification and mass detection in digital breast tomosynthesis  

SciTech Connect

In this article the authors evaluate a recently proposed variable dose (VD)-digital breast tomosynthesis (DBT) acquisition technique in terms of the detection accuracy for breast masses and microcalcification (MC) clusters. With this technique, approximately half of the total dose is used for one center projection and the remaining dose is split among the other tomosynthesis projection views. This acquisition method would yield both a projection view and a reconstruction view. One of the aims of this study was to evaluate whether the center projection alone of the VD acquisition can provide equal or superior MC detection in comparison to the 3D images from uniform dose (UD)-DBT. Another aim was to compare the mass-detection capabilities of 3D reconstructions from VD-DBT and UD-DBT. In a localization receiver operating characteristic (LROC) observer study of MC detection, the authors compared the center projection of a VD acquisition scheme (at 2 mGy dose) with detector pixel size of 100 {mu}m with the UD-DBT reconstruction (at 4 mGy dose) obtained with a voxel size of 100 {mu}m. MCs with sizes of 150 and 180 {mu}m were used in the study, with each cluster consisting of seven MCs distributed randomly within a small volume. Reconstructed images in UD-DBT were obtained from a projection set that had a total of 4 mGy dose. The current study shows that for MC detection, using the center projection alone of VD acquisition scheme performs worse with area under the LROC curve (A{sub L}) of 0.76 than when using the 3D reconstructed image using the UD acquisition scheme (A{sub L}=0.84). A 2D ANOVA found a statistically significant difference (p=0.038) at a significance level of 0.05. In the current study, although a reconstructed image was also available using the VD acquisition scheme, it was not used to assist the MC detection task which was done using the center projection alone. In the case of evaluation of detection accuracy of masses, the reconstruction with VD-DBT (A{sub L}=0.71) was compared to that obtained from the UD-DBT (A{sub L}=0.78). The authors found no statistically significant difference between the two (p-value=0.22), although all the observers performed better for UD-DBT.

Das, Mini; Gifford, Howard C.; O'Connor, J. Michael; Glick, Stephen J. [Department of Radiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, Massachusetts 01655 (United States)

2009-06-15

163

Variable structure control of discretized continuous-time systems  

Microsoft Academic Search

A discrete-time variable structure control technique is presented for uncertain continuous-time systems. The design algorithm makes use of the concept of time-delay control in order to estimate the effects of the system perturbations inside the switching region. The controller performances have been evaluated by simulation using a benchmark problem proposed in literature. A satisfactory behavior is obtained also in the

M. Letizia Corradini; Giuseppe Orlando

1998-01-01

164

Generalized variable projective synchronization of time delayed systems.  

PubMed

We study generalized variable projective synchronization between two unified time delayed systems with constant and modulated time delays. A novel Krasovskii-Lyapunov functional is constructed and a generalized sufficient condition for synchronization is derived analytically using the Lyapunov stability theory and adaptive techniques. The proposed scheme is valid for a system of n-numbers of first order delay differential equations. Finally, a new neural oscillator is considered as a numerical example to show the effectiveness of the proposed scheme. PMID:23556955

Banerjee, Santo; Theesar, S Jeeva Sathya; Kurths, J

2013-03-01

165

Performance of Thermal Mass Flow Meters in a Variable Gravitational Environment  

NASA Technical Reports Server (NTRS)

The performance of five thermal mass flow meters, MKS Instruments 179A and 258C, Unit Instruments UFM-8100, Sierra Instruments 830L, and Hastings Instruments HFM-200, were tested on the KC-135 Reduced Gravity Aircraft in orthogonal, coparallel, and counterparallel orientations relative to gravity. Data was taken throughout the parabolic trajectory where the g-level varied from 0.01 to 1.8 times normal gravity. Each meter was calibrated in normal gravity in the orthogonal position prior to flight followed by ground testing at seven different flow conditions to establish a baseline operation. During the tests, the actual flow rate was measured independently using choked-flow orifices. Gravitational acceleration and attitude had a unique effect on the performance of each meter. All meters operated within acceptable limits at all gravity levels in the calibrated orthogonal position. However, when operated in other orientations, the deviations from the reference flow became substantial for several of the flow meters. Data analysis indicated that the greatest source of error was the effect of orientation, followed by the gravity level. This work emphasized that when operating thermal flow meters in a variable gravity environment, it is critical to orient the meter in the same direction relative to gravity in which it was calibrated. Unfortunately, there was no test in normal gravity that could predict the performance of a meter in reduced gravity. When operating in reduced gravity, all meters indicated within 5 percent of the full scale reading at all flow conditions and orientations.

Brooker, John E.; Ruff, Gary A.

2004-01-01

166

Large Scale Variability Survey of Orion II: mapping the young, low-mass stellar populations  

NASA Astrophysics Data System (ADS)

We present further results of our ongoing large scale variability survey of the Orion OB1 Association, carried out with the 8k x 8k CCD Mosaic Camera on the 1m Schmidt telescope at the Venezuela National Observatory. In an area of over 60 square degrees we have unveiled new populations of low-mass young stars over a range of environments, from the dense molecular clouds of the Orion belt region, Ori OB 1b, to areas devoid of gas in Orion OB 1a. These new young stars span ages from 1-2 Myr in Ori OB 1b to roughly 10 Myr in Ori OB 1a, a likely scenario of sequential star formation triggered by the first generation of massive stars. Proxy indicators like H? emission and near-IR excesses show that accretion from circumstellar disks in the 10 Myr stars of Ori OB 1a has mostly stopped. This population is a numerous analog of groups like TW Hya, making it an excellent laboratory to look for debris disks and study the epoch of planet formation in sparse, non-clustered environments. Research reported herein funded by NSF grant No. 9987367, and by CONICIT and Ministerio de Ciencia y Tecnologa, Venezuela.

Briceo, C.; Calvet, N.; Hartmann, L. W.; Vivas, A. K.

2000-12-01

167

Secular dynamics in hierarchical three-body systems with mass loss and mass transfer  

E-print Network

Recent studies have shown that secular evolution of triple systems can play a major role in the evolution and interaction of their inner binaries. Very few studies explored the stellar evolution of triple systems, and in particular the mass loss phase of the evolving stellar components. Here we study the dynamical secular evolution of hierarchical triple systems undergoing mass loss. We use the secular evolution equations and include the effects of mass-loss and mass-transfer, as well as general relativistic effects. We present various evolutionary channels taking place in such evolving triples, and discuss both the effects of mass-loss and mass-transfer in the inner binary system, as well as the effects of mass-loss/transfer from an outer third companion. We discuss several distinct types/regimes of triple secular evolution, where the specific behavior of a triple system can sensitively depend on its hierarchy and the relative importance of classical and general relativistic effects. We show that the orbital...

Michaely, Erez

2014-01-01

168

Equilibrium points and stability in the restricted three-body problem with oblateness and variable masses  

NASA Astrophysics Data System (ADS)

The existence and stability of a test particle around the equilibrium points in the restricted three-body problem is generalized to include the effect of variations in oblateness of the first primary, small perturbations ? and ?' given in the Coriolis and centrifugal forces ? and ? respectively, and radiation pressure of the second primary; in the case when the primaries vary their masses with time in accordance with the combined Meshcherskii law. For the autonomized system, we use a numerical evidence to compute the positions of the collinear points L 2 ? , which exist for 0< ?mass parameter ? and small perturbation in the centrifugal force. Real out of plane equilibrium points exist only for ?>1, provided the abscissae ?mass parameter. The linear stability of these equilibrium points is examined. It is seen that the collinear points L 2 ? are stable for very small ? and the involved parameters, while the out of plane equilibrium points are unstable. The conditional stability of the triangular points depends on all the system parameters. Further, it is seen in the case of the triangular points, that the stabilizing or destabilizing behavior of the oblateness coefficient is controlled by ?, while those of the small perturbations depends on ? and whether these perturbations are positive or negative. However, the destabilizing behavior of the radiation pressure remains unaltered but grows weak or strong with increase or decrease in ?. This study reveals that oblateness coefficient can exhibit a stabilizing tendency in a certain range of ?, as against the findings of the RTBP with constant masses. Interestingly, in the region of stable motion, these parameters are void for ?=4/3. The decrease, increase or non existence in the region of stability of the triangular points depends on ?, oblateness of the first primary, small perturbations and the radiation pressure of the second body, as it is seen that the increasing region of stability becomes decreasing, while the decreasing region becomes increasing due to the inclusion of oblateness of the first primary.

Singh, Jagadish; Leke, Oni

2012-07-01

169

A mass balance model for the Mapleson D anaesthesia breathing system  

Microsoft Academic Search

A mathematical model is described which calculates the alveolar concentration of$$CO_2 (F_{ACO_2 } )$$ in a patient breathing through a Mapleson D anaesthesia system. The model is derived using a series of mass balances for\\u000a CO2 in the alveolar space, dead space, breathing system limb volume and reservoir. The variables included in the model are tidal\\u000a volume (VT), respiratory rate,

Mark A. Lovich; Brett A. Simon; Jose G. Venegas; Nathanial M. Sims; Jeffrey B. Cooper

1993-01-01

170

Asymmetric mass accretion in the magnetic cataclysmic variable RE 1149 + 28  

NASA Technical Reports Server (NTRS)

We present the first detailed extreme photometric observations of a magnetic cataclysmic variable. Our two Extreme Ultraviolet Explorer (EUVE) observations of the AM Her star RE 1149 + 28 were obtained about 1 yr apart and show light-curve variations on orbital to yearly timescales, as well as long-term mean flux level changes of a factor of 2. The photometric data show a persistent ingress EUV enhancement which lasts approximately 0.04 in phase. We attribute this to a region of approximately 10(exp 3) km in extent at the accretion impact site, on or very near the surface of the white dwarf primary. Our observations of RE 1149 are consistent with a relatively low system inclination and provide a best-fit orbital period of 90.14 +/- 0.015 minutes.

Howell, Steve B.; Sirk, Martin M.; Malina, Roger F.; Mittaz, J. P. D.; Mason, K. O.

1995-01-01

171

Analysis of a Linear System for Variable-Thrust Control in the Terminal Phase of Rendezvous  

NASA Technical Reports Server (NTRS)

A linear system for applying thrust to a ferry vehicle in the 3 terminal phase of rendezvous with a satellite is analyzed. This system requires that the ferry thrust vector per unit mass be variable and equal to a suitable linear combination of the measured position and velocity vectors of the ferry relative to the satellite. The variations of the ferry position, speed, acceleration, and mass ratio are examined for several combinations of the initial conditions and two basic control parameters analogous to the undamped natural frequency and the fraction of critical damping. Upon making a desirable selection of one control parameter and requiring minimum fuel expenditure for given terminal-phase initial conditions, a simplified analysis in one dimension practically fixes the choice of the remaining control parameter. The system can be implemented by an automatic controller or by a pilot.

Hord, Richard A.; Durling, Barbara J.

1961-01-01

172

Earth System Science Education Centered on Natural Climate Variability  

NASA Astrophysics Data System (ADS)

Several new courses and many educational activities related to climate change are available to teachers and students of all grade levels. However, not all new discoveries in climate research have reached the science education community. In particular, effective learning tools explaining natural climate change are scarce. For example, the Pacific Decadal Oscillation (PDO) is a main cause of natural climate variability spanning decades. While most educators are familiar with the shorter-temporal events impacting climate, El Nio and La Nia, very little has trickled into the climate change curriculum on the PDO. We have developed two online educational modules, using an Earth system science approach, on the PDO and its role in climate change and variability. The first concentrates on the discovery of the PDO through records of salmon catch in the Pacific Northwest and Alaska. We present the connection between salmon abundance in the North Pacific to changing sea surface temperature patterns associated with the PDO. The connection between sea surface temperatures and salmon abundance led to the discovery of the PDO. Our activity also lets students explore the role of salmon in the economy and culture of the Pacific Northwest and Alaska and the environmental requirements for salmon survival. The second module is based on the climate of southern California and how changes in the Pacific Ocean , such as the PDO and ENSO (El Nio-Southern Oscillation), influence regional climate variability. PDO and ENSO signals are evident in the long-term temperature and precipitation record of southern California. Students are guided in the module to discover the relationships between Pacific Ocean conditions and southern California climate variability. The module also provides information establishing the relationship between climate change and variability and the state's water, energy, agriculture, wildfires and forestry, air quality and health issues. Both modules will be reviewed for inclusion on the ESSEA (Earth Systems Science Education Alliance) course module list. ESSEA is a NSF-funded organization dedicated to K-12 online Earth system science education.

Ramirez, P. C.; Ladochy, S.; Patzert, W. C.; Willis, J. K.

2009-12-01

173

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

174

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

175

Compressive Mass Analysis on Quadrupole Ion Trap Systems  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

176

CALIBRATING THE CORRELATION BETWEEN BLACK HOLE MASS AND X-RAY VARIABILITY AMPLITUDE: X-RAY ONLY BLACK HOLE MASS ESTIMATES FOR ACTIVE GALACTIC NUCLEI AND ULTRA-LUMINOUS X-RAY SOURCES  

SciTech Connect

A calibration is made for the correlation between the X-ray Variability Amplitude (XVA) and black hole (BH) mass. The correlation for 21 reverberation-mapped Active Galactic Nuclei (AGNs) appears very tight, with an intrinsic dispersion of 0.20 dex. The intrinsic dispersion of 0.27 dex can be obtained if BH masses are estimated from the stellar velocity dispersions. We further test the uncertainties of mass estimates from XVAs for objects that have been observed multiple times with good enough data quality. The results show that the XVAs derived from multiple observations change by a factor of 3. This means that BH mass uncertainty from a single observation is slightly worse than either reverberation-mapping or stellar velocity dispersion measurements; however, BH mass estimates with X-ray data only can be more accurate if the mean XVA value from more observations is used. With this calibrated relation, the BH mass and accretion rate may be determined for a large sample of AGNs with the planned International X-ray Observatory mission. Proper interpretation of the first AGN X-ray quasi-periodic oscillation (QPO), seen in the Seyfert galaxy RE J1034+396, depends on its BH mass, which is not currently known very well. Applying this relation, the BH mass of RE J1034+396 is found to be 4{sup +3}{sub -2} x 10{sup 6} M{sub sun}. The high end of the mass range follows the relationship between the 2f{sub 0} frequencies of high-frequency QPO and the BH masses derived from the Galactic X-ray binaries. We also calculate the high-frequency constant C = 2.37 M{sub sun} Hz{sup -1} from 21 reverberation-mapped AGNs. As suggested by Gierlinski et al., M{sub BH} = C/C{sub M}, where C{sub M} is the high-frequency variability derived from XVA. Given the similar shape of power-law dominated X-ray spectra in ultra-luminous X-ray sources (ULXs) and AGNs, this can be applied to BH mass estimates of ULXs. We discuss the observed QPO frequencies and BH mass estimates in the ULXs M82 X-1 and NGC 5408 X-1 and favor ULXs as intermediate mass BH systems.

Zhou Xinlin [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Zhang Shuangnan [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang Dingxiong [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhu Ling, E-mail: zhouxl@nao.cas.c [Department of Physics and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084 (China)

2010-02-10

177

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

178

Extremal entanglement and mixedness in continuous variable systems  

E-print Network

We investigate extremal entanglement for Gaussian states of continuous variable systems. We introduce generalized entropies based on p-norms to quantify mixedness, and give their explicit expression in terms of symplectic spectra. We compare the hierarchies of mixedness provided by such measures with the one provided by the purity for n-mode states. We then review the argument proving the existence of both maximally and minimally entangled two--mode states at given global and marginal purities (with the entanglement quantified by the logarithmic negativity). Exploiting these results, we extend such an analysis to generalized entropies, fully characterizing maximally and minimally entangled states for given global and local generalized entropies. The privileged role of the purity in quantifying the mixedness of continuous variable systems is stressed and a proposal to estimate entanglement by purity measurements is finally reviewed.

Adesso, G; Illuminati, F

2004-01-01

179

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

180

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...

181

Performance of emotional group robotic system using mass psychology  

Microsoft Academic Search

We propose a new concept of the group robotic system which decides their motion based on the mass psychology. Mass psychology is a subject of behaviour of a crowd of organisms, especially focusing the effect of emotion on the behaviour of a group of organisms. In a group of organisms, the emotion has an effect on their motion and telecommunication

Hidenori ISHIHARA; Toshio FUKUDA

1997-01-01

182

South Atlantic Multidecadal Variability in the Climate System Model  

Microsoft Academic Search

Strong multidecadal variability is detected in a 300-yr integration of the NCAR Climate System Model in the South Atlantic region, through the application of two signal recognition techniques: the multitaper method and singular spectrum analysis. Significant oscillations of a 25-30-yr period are found in the sea surface temperature, sea level pressure, and barotropic transport fields. A similar-scale signal is also

Ilana Wainer; Silvia A. Venegas

2002-01-01

183

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

184

On the use and abuse of Newton's second law for variable mass problems  

Microsoft Academic Search

Solution techniques for celestial mechanics problems involving bodies of varying mass are considered analytically, emphasizing the fact that Newton's second law is valid only for fixed-mass bodies. In the restricted three-body problem, for example, it is pointed out that the motion of a body losing mass isotropically is unaffected by this loss. Expressions to be substituted in the cases of

Angel R. Plastino; Juan C. Muzzio

1992-01-01

185

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

186

Dramatic variability of the carbonate system of the coastal ocean is regulated by physical and biogeochemical processes on multiple timescales  

NASA Astrophysics Data System (ADS)

Increased atmospheric carbon dioxide (CO2) from anthropogenic sources is acidifying marine environments with potentially dramatic implications for the physical, chemical and biological functioning of these ecosystems. If current trends continue, mean ocean pH is expected to decrease by ~0.2 units over the next ~50 years. Yet, at the same time there is substantial spatial and temporal variability in pH and other carbon system parameters in the ocean resulting in regions that already exceed long term projected pH changes, suggesting that short-term variability is an important layer of complexity on top of long term acidification. Thus, in order to develop predictions of future climate change impacts including ocean acidification, there is a critical need to characterize the natural range and variability of the marine CO2 system and the mechanisms responsible for this variability. Here we examine pH and dissolved inorganic carbon (DIC) variability at time intervals spanning 1 hour to >1 year in a dynamic coastal marine system to quantify variability of the carbon system at multiple time scales. Daily and seasonal variability of the carbon system is largely driven by temperature, alkalinity and the balance between primary production and respiration, but high frequency variability (hours to days) is further influenced by water mass movement (e.g. tides) and stochastic events (e.g. storms). Both annual variability (~0.3 units) and diurnal variability (~0.1 units) in coastal ocean acidity are similar in magnitude to long term projections associated with increasing atmospheric CO2 and their drivers highlight the importance of characterizing the complete carbonate system (and not just pH). Short term variability of ocean carbon parameters may already exert significant pressure on some coastal marine ecosystems with implications for ecology, biogeochemistry and evolution and this shorter term variability layers additive effects and complexity, including extreme values, on top of long term trends in ocean acidification.

Johnson, Z. I.; Hunt, D.

2013-12-01

187

Small system for tritium accelerator mass spectrometry  

SciTech Connect

This invention is comprised of an apparatus for ionizing and accelerating a sample containing isotopes of hydrogen and detecting the ratios of hydrogen isotopes contained in the sample. An ion source generates a substantially linear ion beam including ions of tritium from the sample. A radiofrequency 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.

1991-12-31

188

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

189

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

190

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

191

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

192

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

2004-02-18

193

Extremal entanglement and mixedness in continuous variable systems  

NASA Astrophysics Data System (ADS)

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?2 for the state ? ) 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

2004-08-01

194

Variable structure control of nonlinear systems through simplified uncertain models  

NASA Technical Reports Server (NTRS)

A variable structure control approach is presented for the robust stabilization of feedback equivalent nonlinear systems whose proposed model lies in the same structural orbit of a linear system in Brunovsky's canonical form. An attempt to linearize exactly the nonlinear plant on the basis of the feedback control law derived for the available model results in a nonlinearly perturbed canonical system for the expanded class of possible equivalent control functions. Conservatism tends to grow as modeling errors become larger. In order to preserve the internal controllability structure of the plant, it is proposed that model simplification be carried out on the open-loop-transformed system. As an example, a controller is developed for a single link manipulator with an elastic joint.

Sira-Ramirez, Hebertt

1986-01-01

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

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 Earths 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 13years (19942006) 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 36,055km3/y for the study period while exhibiting significant interannual variability driven primarily by El Nio 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 540km3/y2, which was largely attributed to an increase of global-ocean evaporation (768km3/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

197

Determination of intratest variability of trace elements in foraminifera by laser ablation inductively coupled plasma-mass spectrometry  

NASA Astrophysics Data System (ADS)

We have developed a technique to determine the variability of trace elements (including Li, B, Na, Mg, Mn, Cu, Zn, Sr and Ba) within foraminifera tests using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This technique has a high spatial resolution (width 40-80 ?m, depth >0.5 ?m), is reproducible (<8% external reproducibility) and has low detection limits (generally <0.05 ?g g-1). We demonstrate that normalization of data to a calcite standard usually gives results that are more consistent with solution ICP-MS data than normalization to NIST 612. Rastering into the wall of the final chamber of Globigerinoides sacculifer shows that the outermost 1.5 ?m of the test is enriched in trace elements, including Mn, relative to the interior, indicating the presence of a contaminant surface phase. Pustule calcite close to the aperture of Globorotalia tumida has different Sr/Ca and Ba/Ca compared to other parts of the test. Sr/Ca and Ba/Ca partition coefficients suggest that the pustule calcite is diagenetic and/or formed in a more open system. Multiple analyses of Orbulina universa tests recovered from a latitudinal transect in the North Atlantic give a relationship between Mg/Ca and sea surface temperature similar to that reported elsewhere in the literature. These initial data demonstrate the validity of this technique, and show that it is potentially an extremely powerful microanalytical tool for palaeoceanographic and palaeontological studies.

Hathorne, E. C.; Alard, O.; James, R. H.; Rogers, N. W.

2003-12-01

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

Mass Measurement System Using Relay Feedback with Hysteresis  

NASA Astrophysics Data System (ADS)

Mass measurement using a relay feedback system was studied experimentally. The measurement system has an on-off relay with hysteresis and switches force acting on the object in relation to its velocity. Such nonlinear control induces a limit cycle in the feedback system. The mass of the object is determined from the period of this limit cycle. The apparatus manufactured for experimental study uses two voice coil motors (VCM's), one of which is for driving the object and the other is for generating prescribed disturbances. The effects of system parameters and disturbances on measurement accuracy were examined experimentally.

Mizuno, Takeshi; Adachi, Takahiro; Takasaki, Masaya; Ishino, Yuji

200

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

201

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

202

Decentralization of Coordination Variables in Multi-vehicle Systems Wei Ren, Member, IEEE  

E-print Network

Decentralization of Coordination Variables in Multi-vehicle Systems Wei Ren, Member, IEEE Abstract level information formalized as "coordination variables" on each vehicle. We then develop consensus strategies to guarantee that each coordination variable instantiation converges to a sufficiently common

Ren, Wei

203

Cataclysmic variables  

Microsoft Academic Search

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

Robert Connon Smith

2006-01-01

204

The mass, energy, space and time systemic theory-MEST  

NASA Astrophysics Data System (ADS)

The solar system is mass-energy center, and the wave (space-time) and planet are around. Sun absorb the matter (mass-energy) and radiate the light (space-time). The dark hole system is the space-time center, and the dark matter-energy and dark planet (dark comet-asteroid) are around. Dark hole absorb the light (space-time), and radiate the dark mass-energy (mass-energy). So the dark mass-energy main make up of the negative proton and the negative neutron who can take negative density and negative pressure. The cosmological model is like ``Taiji'' model which is from Ancient China. The black hole (invisible stuff) has not a big mass and energy. The light can not leave off it, because it absorb the light. So it can cause the ``red-shift.'' Sun has a companion dark hole. When it recurrent visit solar system, it can take ``red-shift speeded up,'' and can take many dark comet-asteroids to impact near our earth. When the dark mass-energy go into the solar corona, The electron neutrinos can bombard the negative neutron and the negative proton, and take the a reaction with them. It's equation: n^-+ve -> p+?, p^-+ve -> n+?. Among it, n^-: the negative neutron, p^-: the negative proton, ve: the electron neutrino, p: the proton, n: the neutron, ?: the muon. We will use them to change the orbit of earth and dark comet for avoiding its impaction.

Cao, Dayong

2010-11-01

205

Dynamical Equations, Invariants and Spectrum Generating Algebras of Mechanical Systems with Position-Dependent Mass  

E-print Network

We analyze the dynamical equations obeyed by a classical system with position-dependent mass. It is shown that there is a non-conservative force quadratic in the velocity associated to the variable mass. We construct the Lagrangian and the Hamiltonian for this system and find the modifications required in the Euler-Lagrange and Hamilton's equations to reproduce the appropriate Newton's dynamical law. Since the Hamiltonian is not time invariant, we get a constant of motion suited to write the dynamical equations in the form of the Hamilton's ones. The time-dependent first integrals of motion are then obtained from the factorization of such a constant. A canonical transformation is found to map the variable mass equations to those of a constant mass. As particular cases, we recover some recent results for which the dependence of the mass on the position was already unnoticed, and find new solvable potentials of the P\\"oschl-Teller form which seem to be new. The latter are associated to either the su(1,1) or the su(2) Lie algebras depending on the sign of the Hamiltonian.

Sara Cruz y Cruz; Oscar Rosas-Ortiz

2012-08-11

206

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

207

AN EVALUATION OF THE VARIABILITY OF AIR MASS CHARACTER BETWEEN URBAN AND RURAL AREAS  

E-print Network

, Delaware ABSTRACT While numerous studies have examined the magnitude of the urban heat island, no large masses show considerably larger urban heat island disparities than the three "moist" air masses locations, the summer urban heat island appears to be strengthening, whereas in winter little to no change

Sheridan, Scott

208

Variable Stars and The Asymptotic Giant Branch: Stellar Pulsations, Dust Production, and Mass Loss  

NASA Astrophysics Data System (ADS)

Low- and intermediate-mass stars (18 M?; LIMS) are very important contributors of material to the interstellar medium (ISM), and yet the mechanisms by which this matter is expelled remain a mystery. In this paper we discuss how interferometry plays a role in studying the interplay between pulsation, mass loss, dust formation, and evolution of these LIMS.

Speck, A. K.

2014-09-01

209

Variable Stars and the Asymptotic Giant Branch: Stellar Pulsations, Dust Production, and Mass Loss  

NASA Astrophysics Data System (ADS)

Low- and intermediate-mass stars (1-8 M?; LIMS) are very important contributors of material to the interstellar medium (ISM), and yet the mechanisms by which this matter is expelled remain a mystery. In this paper we discuss how interferometry plays a role in studying the interplay between pulsation, mass loss, dust formation and evolution of these LIMS.

Speck, A. K.

2012-06-01

210

Masses of Early-type contact binary systems  

NASA Astrophysics Data System (ADS)

In general, the mass ratio derived from photometric analyses, q(pe), agrees quite well with the value derived from double-line spectroscopic binary, q(sp), for wide pairs as well as for the close pairs. Therefore one wishes that masses could be determined for single-line systems with the help of photometric mass ratio. It is believed that the large masses determined for early type contact systems may be not reliable or quite wrong due to misleading photometric solution, mass ratios. Of course this includes some of my old published papers as well. The appearance of continuous light variation of their light curves resembles a system with contact configuration. In general, the temperature difference between the components is relatively well determined from the differential depths of the eclipses. Most of these systems have large temperature differences. In mode 3 (most popular) contact configuration of W-D method would automatically ends up with a very large temperature discontinuity at the interface. Even though some of our (with D. Q. Zhou of Peking University) model calculations on circulation in contact atmosphere did arrive at stable flow. (The mathematics just becomes too difficult to handle.) One can easily argue that such temperature discontinuity in a system can not be stable. If one utilizes the mode 1 configuration of the W-D method, there would not be a temperature discontinuity at the interface but than the temperature difference derived would not agree with the differential depths of eclipses. The key problem comes from the fact that there is only very slight difference in the shape of the light curves between a contact system and a very close semidetached system. Essentially there is no inflection point in the contact light curve while there is a slight inflection point for the latter. Since we are dealing with O and early B stars there are serious stellar winds and wind-wind interaction to be considered. These could well smooth out the slight the infection point of a semidetacted light curve so as to mimic a contact light curve. It is suspect that this misleading configuration led to the wrong mass ratio and in turn resulted in very large masses. Therefore one should not trust the automatically arrived contact solution for these systems. Then one should limit the solution to semidetacted configure (mode 3 or 4 of the W-D method) for those systems. Therefore it is recommended that the observations of these systems should be re-analyzed. Since most of these system are single-line binaries one might be able to obtain more reasonable masses with reliable photometric mass ratios.

Leung, K. C.

2007-08-01

211

Intake of sweet foods and counts of cariogenic microorganisms in relation to body mass index and psychometric variables in women  

Microsoft Academic Search

OBJECTIVE: As a part of the SPAWN (Stockholm Pregnancy and Women's Nutrition) study, the intake of sweet foods (habitual and pre-menstrual intakes) and the number of cariogenic microorganisms in saliva was analysed in relation to body mass index (BMI) and psychometric variables.DESIGN: A cross-sectional study.SUBJECTS: Three hundred and sixty-two women with a median BMI of 24.2 kg\\/m2 (range 17.547.8) and

B Barkeling; Y Linn; AK Lindroos; D Birkhed; P Rooth; S Rssner

2002-01-01

212

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, Jrgen; Sasgen, Ingo; Thomas, Maik

2014-05-01

213

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.; Daz Trigo, M.; Mikovi?ov, I.

2014-02-01

214

Influence of system mass on the emission of intermediate mass fragments  

E-print Network

In the present study, we have simulated the central reactions of nearly symmetric and asymmetric systems over the entire periodic table for different values of energies using QMD model as event generator. These reactions are simulated for the different equations of state, nn cross-sections and different widths of Gaussians. We have observed that the multiplicity of IMFs shows a rise and fall with increase in beam energy in the center-of-mass frame as already predicted experimentally/theoretically. We have also studied the mass dependence of peak Ec.m. and peak . It has been observed that peak Ec.m. increases linearly with system mass whereas a power law dependence has been observed for peak IMFs with tau \\approx 1.0. Our calculations using hard EoS along with cugnon cross-section and MSTB method are in good agreement with experimental data. Similar power law dependence is also observed for various fragments.

Sukhjit Kaur; Supriya Goyal; Rajeev K. Puri

2011-02-19

215

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

216

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

217

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

218

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

219

Multi-agent System for Mass Spectrometry Analysis  

Microsoft Academic Search

\\u000a This paper presents a framework for rapid distributed application development in mass spectrometry data analysis. The proposed\\u000a system includes an extensible and flexible workflow that covers the whole data analysis process. This workflow was designed\\u000a to be easily distributed and parallelized by implementing the underlying framework as a multi-agent system.

Miguel Reboiro-Jato; Daniel Glez-Pea; Hugo M. Santos; Mrio S. Diniz; Carlos Lodeiro; Jos L. Capelo; Florentino Fdez-Riverola

2010-01-01

220

Building an ensemble system for diagnosing masses in mammograms  

Microsoft Academic Search

PurposeClassification of a suspicious mass (region of interest, ROI) in a mammogram as malignant or benign may be achieved using\\u000a mass shape features. An ensemble system was built for this purpose and tested.\\u000a \\u000a \\u000a \\u000a \\u000a MethodsMultiple contours were generated from a single ROI using various parameter settings of the image enhancement functions for\\u000a the segmentation. For each segmented contour, the mass shape

Yu Zhang; Noriko Tomuro; Jacob Furst; Daniela Stan Raicu

221

Satellite Masses in the Uranus and Neptune Systems  

NASA Technical Reports Server (NTRS)

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/cu cm.

Greenberg, R.

1984-01-01

222

Solutions to the restricted three-body problem with variable mass  

E-print Network

We look for particular solutions to the restricted three-body problem where the bodies are allowed to either lose or gain mass to or from a static atmosphere. In the case that all the masses are proportional to the same function of time,we find analogous solution to the five stationary solutions of the usual restricted problem of constant masses: the three collinear and the two triangular solutions, but now the relative distance of the bodies changes with time at the same rate. Under some restrictions, there are also coplanar, infinitely remote and ring solutions.

Tiago Amancio da Silva; P. S. Letelier

2011-03-16

223

External mass transfer in high performance liquid chromatography systems  

Microsoft Academic Search

External mass transfer in a HPLC system operated in the reversed-phase mode was studied by pulse response experiments, using a column packed with non-porous C18-silica gel spherical particles, 18?m in diameter. The first and second moments of the elution peaks, measured under different flow velocities and temperatures, were analyzed by the moment method to determine the external mass transfer coefficient

Kanji Miyabe; Motoki Ando; Nobuho Ando; Georges Guiochon

2008-01-01

224

Dyslexia Marker Variables: Reviving a System for Reporting Sample Characteristics in Learning Disabilities Research.  

ERIC Educational Resources Information Center

Discusses the definition of dyslexia, reintroduces the concept of marker variables, proposes a strategy for developing an updated marker variable system, presents a preliminary working set of dyslexia marker variables, and calls for eventual adoption of this or similar marker variable systems to facilitate future research efforts. (Author/CR)

Spagna, Michael E.

1998-01-01

225

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

226

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

227

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

228

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) entang...

Adesso, G; Illuminati, F; Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio

2005-01-01

229

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

230

Modeling of Vertical Ground Loop Heat Exchangers with Variable Convective Resistance and Thermal Mass of the Fluid  

E-print Network

source heat pump (GSHP) systems. Thermal load profiles vary significantly from building to building of the system, as the COP of the heat pump varies with entering fluid temperature. Therefore, it is desirableModeling of Vertical Ground Loop Heat Exchangers with Variable Convective Resistance and Thermal

231

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

Microsoft Academic Search

With the current movement toward net zero energy buildings, many technologies are promoted with emphasis on their superior energy efficiency. The variable refrigerant flow (VRF) and ground source heat pump (GSHP) systems are probably the most competitive technologies among these. However, there are few studies reporting the energy efficiency of VRF systems compared with GSHP systems. In this article, a

Tainzhen Hong; Xaiobing Liu

2009-01-01

232

Comparison of energy efficiency between variable refrigerant flow systems and ground source heat pump systems  

Microsoft Academic Search

With the current movement towards net zero energy buildings, many technologies are promoted with emphasis on their superior energy efficiency. The variable refrigerant flow (VRF) and ground source heat pump (GSHP) systems are probably the most competitive technologies among these. However, there are few studies reporting the energy efficiency of VRF systems compared with GSHP systems. In this article, a

Xiaobing Liu; Tianzhen Hong

2010-01-01

233

Assessing the precision on the determination of the Martian CO2 seasonal mass budget from time-variable gravity observations  

NASA Astrophysics Data System (ADS)

A relative large amount of the CO2 of the atmosphere of Mars is seasonally exchanged with the surface through the condensation/sublimation process at the polar caps. The associated mass redistribution at planetary scale generates a fine seasonal variation of the gravity field of Mars, allowing for the estimation of the mass budget of the CO2 seasonal cycle at the polar caps. However, to derive this mass budget, the knowledge of the extent and of the CO2 deposit density of the caps is needed in addition to the determination of the time variable gravity field. In this study, the time variable gravity solution is obtained from the Precise Orbit Determination (POD) of Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) spacecraft. All tracking data from the beginning of the nominal mission up to the most recent available extended phases for each spacecraft have been taken into account, thus covering about 5 Martian years. From this dataset, the seasonal variations of the lumped zonal harmonics of degree two and three have been obtained, using the GINS software developed by the CNES and further adapted by Royal Observatory of Belgium for planetary geodesy applications. The extent of the polar caps has been modeled on the basis of the MGS/TES dataset. In addition, the effect of compaction on the volume density of the polar CO2 deposits has been taken into account. Both the time variable gravity solution (i.e. lumped zonal harmonics) and the polar caps model have been compared with outputs of Global Circulation Model (GCM), and with the estimation derived from the HEND data onboard Mars Odyssey, in order to assess the precision on the current estimation of the polar cap CO2 mass budget.

Rosenblatt, P.; Marty, J.; Le Maistre, S.; Dehant, V. M.; Karatekin, O.

2009-12-01

234

Orbits and masses in the young triple system TWA 5  

NASA Astrophysics Data System (ADS)

Aims: We aim to improve the orbital elements and determine the individual masses of the components in the triple system TWA 5. Methods: Five new relative astrometric positions in the H band were recorded with the adaptive optics system at the Very Large Telescope (VLT). We combine them with data from the literature and a measurement in the Ks band. We derive an improved fit for the orbit of TWA 5Aa-b around each other. Furthermore, we use the third component, TWA 5B, as an astrometric reference to determine the motion of Aa and Ab around their center of mass and compute their mass ratio. Results: We find an orbital period of 6.03 0.01 years and a semi-major axis of 63.7 0.2 mas (3.2 0.1 AU). With the trigonometric distance of 50.1 1.8 pc, this yields a system mass of 0.9 0.1 M?, where the error is dominated by the error of the distance. The dynamical mass agrees with the system mass predicted by a number of theoretical models if we assume that TWA5 is at the young end of the age range of the TW Hydrae association. We find a mass ratio of MAb/MAa = 1.3-0.4+0.6 , where the less luminous component Ab is more massive. This result is likely to be a consequence of the large uncertainties due to the limited orbital coverage of the observations. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 079.C-0103, 081.C-0393, 386.C-0205, 087.C-0209, 088.C-0046, 089.C-0167, and 090.C-0184.

Khler, R.; Ratzka, T.; Petr-Gotzens, M. G.; Correia, S.

2013-10-01

235

Heat and mass transfer considerations in advanced heat pump systems  

SciTech Connect

Advanced heat-pump cycles are being investigated for various applications. However, the working media and associated thermal design aspects require new concepts for maintaining high thermal effectiveness and phase equilibrium for achieving maximum possible thermodynamic advantages. In the present study, the heat- and mass-transfer processes in two heat-pump systems -- those based on absorption processes, and those using refrigerant mixtures -- are analyzed. The major technical barriers for achieving the ideal performance predicted by thermodynamic analysis are identified. The analysis provides general guidelines for the development of heat- and mass-transfer equipment for advanced heat-pump systems.

Panchal, C.B.; Bell, K.J.

1992-01-01

236

Heat and mass transfer considerations in advanced heat pump systems  

SciTech Connect

Advanced heat-pump cycles are being investigated for various applications. However, the working media and associated thermal design aspects require new concepts for maintaining high thermal effectiveness and phase equilibrium for achieving maximum possible thermodynamic advantages. In the present study, the heat- and mass-transfer processes in two heat-pump systems -- those based on absorption processes, and those using refrigerant mixtures -- are analyzed. The major technical barriers for achieving the ideal performance predicted by thermodynamic analysis are identified. The analysis provides general guidelines for the development of heat- and mass-transfer equipment for advanced heat-pump systems.

Panchal, C.B.; Bell, K.J.

1992-08-01

237

Spectral analysis for semi-infinite mass-spring systems  

E-print Network

We study how the spectrum of a Jacobi operator changes when this operator is modified by a certain finite rank perturbation. The operator corresponds to an infinite mass-spring system and the perturbation is obtained by modifying one interior mass and one spring of this system. In particular, there are detailed results of what happens in the spectral gaps and which eigenvalues do not move under the modifications considered. These results were obtained by a new tecnique of comparative spectral analysis and they generalize and include previous results for finite and infinite Jacobi matrices.

Rafael del Rio; Luis O. Silva

2013-12-25

238

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

239

The anterior jugular venous system: variability and clinical impact.  

PubMed

The anterior jugular venous system, with its interconnections to the subclavian and deep jugular veins, provides a collateral venous network across the midline of the neck area, which is especially important in unilateral occlusion of an innominate vein. We illustrate the variability of this system and its clinical impact on catheterization by three cases of landmark-guided central venous cannulation. Case 1: Cannulation of the left internal jugular vein with a central venous catheter and of the left innominate vein (LIV) with a pulmonary artery catheter resulted in correctly positioned catheter tips. However, these catheters were actually not placed in the innominate vein but coursed through the jugular venous arch. Case 2: Cannulation of the left subclavian vein was complicated by resistance of guidewire advancement at 13 cm. Occlusion of the LIV and enlargement of the jugular venous arch were present. Case 3: Insertion of a pulmonary artery catheter and a central venous catheter through the LIV. The pulmonary artery catheter was correctly placed. The tip of the central venous catheter was mistakenly positioned in the left anterior jugular vein. We describe the normal anatomy of the anterior jugular venous system and its role as a major collateral. Correct placement of central venous catheters may be possible via the anterior jugular venous system. Conversely, central venous catheters malpositioned in the anterior jugular vein can increase the risk for complications and should be removed. PMID:15562044

Schummer, Wolfram; Schummer, Claudia; Bredle, Don; Frber, Rosemarie

2004-12-01

240

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

241

Maternal provisioning, sibling rivalry and seed mass variability in the dioecious shrub Rhamnus alpinus  

Microsoft Academic Search

In this paper, we study the sources of variability in seed provisioning in Rhamnus alpinus, a dioecious shrub producing three-seeded fleshy fruits (range 14). Discarding position effects in access to resources as a source of variation, since pyrenes are radially oriented inside the fruit, we conducted a pollination experiment, in which different pollen donors were used to make single and

M. J. Bauelos; J. R. Obeso

2003-01-01

242

Validation of a Body Condition Scoring System in Rhesus Macaques (Macaca mulatta): Inter- and Intrarater Variability  

PubMed Central

Body condition scoring (BCS) is a subjective semiquantitative method of assessing body fat and muscle. Scoring systems use a scale in which the midrange represents optimal body condition, lower values represent lean to emaciated conditions, and higher values indicate excessive body fat. A valid BCS system is clearly described, relevant to the species, shows agreement within and between raters, and is consistent with objective measures. The goal of the current study was to assess intra- and interrater variability of a BCS system that uses a 1-to-5 scale and entails the palpation of key anatomic sites (hips, spine, pelvis, thorax, and abdomen) to assess prominence of bony structures, muscle mass, and subcutaneous fat. To assess interrater variability, 4 raters independently assessed BCS in 616 rhesus macaques (Macaca mulatta) in 4 age groups: infant, younger than 1 y; juvenile, 1 to 4 y; subadult, 4 to 7 y; and adult, 7 to 17 y. To assess intrarater variability, each rater independently reevaluated a subset of adult macaques (n = 15) within 2 wk of initial evaluation. A weighted ? score was used to analyze intra- and interrater variability. Agreement between raters was highest for subadult and adult macaques, intermediate for juveniles, and least for infants. Intrarater agreement was high for all raters except one, for which it was moderate. Our results suggest that raters applied the BCS system most consistently to adult and subadult macaques and less so to juvenile and infant animals. However, the percentage agreement between raters to within one half of a score unit increased markedly when raters scored infants in the context of as is rather than ideal for age. PMID:22330865

Clingerman, Karen J; Summers, Laura

2012-01-01

243

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

244

Mass transfer in eccentric binary systems using the binary evolution code BINSTAR  

NASA Astrophysics Data System (ADS)

Context. Studies of interacting binary systems typically assume that tidal forces have circularized the orbit by the time Roche lobe overflow (RLOF) commences. However, recent observations of ellipsoidal variables have challenged this assumption. Aims: We present the first calculations of mass transfer via RLOF for a binary system with a significant eccentricity using our new binary stellar evolution code. The study focuses on a 1.50+1.40 M? main sequence binary with an eccentricity of 0.25, and an orbital period of Porb ? 0.7 d. The reaction of the stellar components due to mass transfer is analysed, and the evolution of mass transfer during the periastron passage is compared to recent smooth particle hydrodynamics (SPH) simulations. The impact of asynchronism and non-zero eccentricity on the Roche lobe radius, and the effects of tidal and rotational deformation on the stars' structures, are also investigated. Methods: Calculations were performed using the state-of-the-art binary evolution code BINSTAR, which calculates simultaneously the structure of the two stars and the evolution of the orbital parameters. Results: The evolution of the mass transfer rate during an orbit has a Gaussian-like shape, with a maximum at periastron, in qualitative agreement with SPH simulations. The Roche lobe radius is modified by the donor star's spin and the orbital eccentricity. This has a significant impact on both the duration and the rate of mass transfer. We find that below some critical rotation rate, mass transfer never occurs, while above some threshold, mass is transferred over the entire orbit. Tidal and rotational deformation of the donor star causes it to become over-sized, enhancing the mass transfer rate further by up to about a factor of ten, leading to non-conservative mass transfer. The modulation of the mass transfer rate with orbital phase produces short-term variability in the surface luminosity and radius of each star. The longer-term behaviour shows, in accordance with studies of circular systems with radiative stars, that the donor becomes ever small and under-luminous, while the converse is the case for the accretor.

Davis, P. J.; Siess, L.; Deschamps, R.

2013-08-01

245

Motion Planning for Dynamic Variable Inertia Mechanical Systems with Non-holonomic  

E-print Network

Motion Planning for Dynamic Variable Inertia Mechanical Systems with Non-holonomic Constraints Elie problem for underactuated variable inertia mechanical systems. Additionally, we analyze a rather general mechanical system, the variable inertia snakeboard, which is a generalization of the original snakeboard

Choset, Howie

246

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

247

Resonance Ionization Mass Spectrometry System for Measurement of Environmental Samples  

NASA Astrophysics Data System (ADS)

A resonance ionization mass spectrometry (RIMS) system has been developed at the National Institute of Standards and Technology (NIST) for sensitive and selective determination of radio-cesium in the environment. The overall efficiency was determined to be 410-7 with a combined (laser and mass spectrometer) selectivity of 108 for both 135Cs and 137Cs with respect to 133Cs. RIMS isotopic ratio measurements of 135Cs/ 137Cs were performed on a nuclear fuel burn-up sample and compared to measurements on a similar system at Pacific Northwest National Laboratory (PNNL) and to conventional thermal ionization mass spectrometry (TIMS). Results of preliminary RIMS investigations on a freshwater lake sediment sample are also discussed.

Pibida, L.; McMahon, C. A.; Nrtershuser, W.; Bushaw, B. A.

2002-10-01

248

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

NASA Astrophysics Data System (ADS)

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, flexible power converters and innovated controllers, the doubly fed machines could favorably compete for many applications, which may also include variable speed power generations. The goal of this research is to enhance the attractiveness of the doubly fed machines for both variable speed drive and variable speed generator applications. Recognizing that wind power is one of the favorable clean, renewable energy sources that can contribute to the solution to the energy and environment dilemma, a novel variable-speed constant-frequency wind power generating system is proposed. By variable speed operation, energy capturing capability of the wind turbine is improved. The improvement can be further enhanced by effectively utilizing the doubly excited brushless reluctance machine in slip power recovery configuration. For the doubly fed machines, a stator flux two -axis dynamic model is established, based on which a flexible active and reactive power control strategy can be developed. High performance operation of the drive and generating systems is obtained through advanced control methods, including stator field orientation control, fuzzy logic control and adaptive fuzzy control. System studies are pursued through unified modeling, computer simulation, stability analysis and power flow analysis of the complete drive system or generating system with the machine, the converter and the control. Laboratory implementations and tested results with a digital signal processor system are also presented.

Tang, Yifan

249

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

250

EJB-MVC oriented supplier selection system for mass customization  

Microsoft Academic Search

Purpose The purpose of this research is to develop a distributed system with an innovative supplier selection approach within a mass customization (MC) environment. The aim is to help manufacturers to identify appropriate suppliers for the components, materials and services required within the procedure of product design and manufacture. Design\\/methodology\\/approach To identify the barriers for the supplier selection

Jiachen Hou; Daizhong Su

2007-01-01

251

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

252

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

253

Training of fuzzy inference systems by combining variable structure systems technique and Levenberg-Marquardt algorithm  

Microsoft Academic Search

This paper presents a novel training algorithm for fuzzy inference systems. The algorithm combines the Levenberg-Marquardt algorithm with variable structure systems approach. The combination is performed by expressing the parameter update rule in continuous time and application of sliding control method to the gradient based training procedure. In this paper, a fuzzy inference mechanism that can be trained such that

M. Onder Efe; Okyay Kaynak; Bogdan M. Wilamowski

1999-01-01

254

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

NASA Astrophysics Data System (ADS)

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 (\\dot\\Pi}) 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 \\dot\\Pi} 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 macos 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.

Crsico, A. H.; Althaus, L. G.; Romero, A. D.; Mukadam, A. S.; Garca-Berro, E.; Isern, J.; Kepler, S. O.; Corti, M. A.

2012-12-01

255

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

256

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

257

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

258

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

259

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 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.; Gonzlez-Jimnez, Nicols; Langer, Norbert; Barb, Rodolfo

2014-10-01

260

Probing the geometric nature of particles mass in graphene systems  

E-print Network

According to undulatory mechanics, the Compton periodicity, which is the intrinsic proper-time recurrence of a wave function, determines the mass of the corresponding elementary particles. This provides a geometric description of the rest mass which can be consistently applied to derive the effective mass spectrum and electronic properties of the elementary charge carriers in carbon nanotubes and other condensed matter systems. The Compton periodicity is determined by the boundary conditions associated to the curled-up dimension of carbon nanotubes or analogous constraints of the charge carrier wave function. This approach shows an interesting interplay between particle physics and relativistic space-time, as well as analogies with the Kaluza-Klein theory and Holography.

Donatello Dolce; Andrea Perali

2014-03-13

261

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

262

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 noisecontrol 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

263

Angular Momentum and Galaxy Formation Revisited: Effects of Variable Mass-to-light Ratios  

NASA Astrophysics Data System (ADS)

We rederive the relation between the specific angular momentum j sstarf and the mass M sstarf of the stellar matter in galaxies of different morphological types. This is a revision of the j sstarf-M sstarf diagram presented in our recent comprehensive study of galactic angular momentum. In that work, we estimated j sstarf from kinematic and photometric data that extended to large radii and M sstarf from near-infrared luminosities LK with an assumed universal mass-to-light ratio M sstarf/LK . However, recent stellar population models show large variations in M sstarf/LK correlated with B - V color. In the present work, we use this correlation to estimate M sstarf/LK and hence M sstarf from the measured B - V and LK . Our revised j sstarf-M sstarf diagram is similar to our previous one; both disk-dominated and elliptical galaxies follow nearly parallel sequences with j_\\star \\propto M_{\\star }^{\\alpha } and ? = 0.6 0.1. However, the offset between the sequences is now a factor of about 5, some 30% larger than before (and close to the offset found by Fall in 1983). Thus, our new results place even tighter constraints on the loss of specific angular momentum by galactic disks over their lifetimes.

Fall, S. Michael; Romanowsky, Aaron J.

2013-06-01

264

Battery energy storage system for variable speed driven PMSG for wind energy conversion system  

Microsoft Academic Search

There are many loads such as remote villages, islands, etc. that are located far away from the main grid. These loads require stand-alone generating system, which can provide constant voltage and frequency for local electrification. Locally available wind power can be used in such off-grid systems. As the wind speed is variable, an AC-DC-AC conversion system is required to convert

Rajveer Mittal; K. S. Sandhu; D. K. Jain

2010-01-01

265

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

266

Annual variation of coastal uplift in Greenland as an indicator of variable and accelerating ice mass loss  

NASA Astrophysics Data System (ADS)

Seasonal melting of the coastal part of the Greenland ice sheet is investigated using GPS vertical displacement data from coastal stations, combined with data on atmospheric and ocean temperatures. Using a high pass filter and cubic spline models, we estimate five variables describing seasonal uplift, a proxy for proximal mass loss, including duration of the melt season and the amount of summer uplift. Our analysis shows both temporal and spatial variations of uplift. Southern coastal Greenland experienced anomalously large uplift in summer 2010, implying significant melting that year. However, the northwest coast did not experience significant change in uplift at that time. Our data suggest that a combination of warm summer air temperature and warm sub-surface ocean water temperature drove the large mass losses in 2010. Using the uplift pattern of 2008-2010, and comparing to atmospheric data and ocean water temperature data, we show that warm Irminger Water (IW) exerted significant influence on coastal melting in southeastern, southern and southwestern Greenland, reaching about 69N in 2010. North of this, IW did not exert significant influence, in effect defining the northward limit of the sub-polar gyre for that year. Thus, short-term variability in the coastal GPS uplift signal can be used to infer an oceanographic parameter that has a critical influence on Greenland ice sheet health.

Yang, Qian; Wdowinski, Shimon; Dixon, Timothy H.

2013-05-01

267

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

268

Student understanding of control of variables: Deciding whether or not a variable influences the behavior of a system  

NASA Astrophysics Data System (ADS)

The ability of adult students to reason on the basis of the control of variables was the subject of an extended investigation. This paper describes the part of the study that focused on the reasoning required to decide whether or not a given variable influences the behavior of a system. The participants were undergraduates taking introductory Physics and K-8 teachers studying physics and physical science in inservice institutes and workshops. Although most of the students recognized the need to control variables, many had significant difficulty with the underlying reasoning. The results indicate serious shortcomings in the preparation of future scientists and in the education of a scientifically literate citizenry. There are also strong implications for the professional development of teachers, many of whom are expected to teach control of variables to young students.

Boudreaux, Andrew; Shaffer, Peter S.; Heron, Paula R. L.; McDermott, Lillian C.

2008-02-01

269

Phytoplankton scales of variability in the California Current System: 2. Latitudinal variability  

E-print Network

), suggesting that the same processes determine the distribution of both. Farther offshore of physical variability are reflected in the distribution of biological parameters is poorly known. To investigate the latitudinal distribution of chlorophyll variance, a wavelet analysis is applied to nearly 9

Thomas, Andrew

270

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

271

Clumped stellar winds in supergiant high-mass X-ray binaries: X-ray variability and photoionization  

NASA Astrophysics Data System (ADS)

The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. The purpose of this paper is to bridge the gap between detailed models of inhomogeneous stellar winds in single stars and the phenomenological description of donor winds in supergiant high-mass X-ray binaries (HMXBs). We use the results from time-dependent hydrodynamical models of the instability in the line-driven wind of a massive supergiant star to derive the time-dependent accretion rate on to a compact object in the Bondi-Hoyle-Lyttleton approximation. The strong density and velocity fluctuations in the wind result in strong variability of the synthetic X-ray light curves. The model predicts a large-scale X-ray variability, up to eight orders of magnitude, on relatively short time-scales. The apparent lack of evidence for such strong variability in the observed HMXBs indicates that the details of the accretion process act to reduce the variability resulting from the stellar wind velocity and density jumps. We study the absorption of X-rays in the clumped stellar wind by means of a two-dimensional stochastic wind model. The monochromatic absorption in the cool stellar wind, depending on the orbital phase, is computed for realistic stellar wind opacity. We find that the absorption of X-rays changes strongly at different orbital phases. The degree of the variability resulting from the absorption in the wind depends on the shape of the wind clumps, and this is stronger for oblate clumps. We address the photoionization in the clumped wind, and we show that the degree of ionization is affected by the wind clumping. We derive a correction factor for the photoionization parameter, and we show that the photoionization parameter is reduced by a factor ? compared to the smooth wind models with the same mass-loss rate, where ? is the wind inhomogeneity parameter. We conclude that wind clumping must also be taken into account when comparing the observed and model spectra of the photoionized stellar wind.

Oskinova, L. M.; Feldmeier, A.; Kretschmar, P.

2012-04-01

272

Characterizing the quiescent X-ray variability of the black hole low mass x-ray binary V404 Cyg  

E-print Network

We conducted the first long-term (75 days) X-ray monitoring of the black hole low mass X-ray binary V404 Cyg, with the goal of understanding and characterizing its variability during quiescence. The X-ray light curve of V404 shows several flares on timescales of hours with a count rate change of a factor of about 5-8. The root mean square variability is Fvar = 57.0(3.2) percent. The first order structure function is consistent with both a power spectrum of index -1 (flicker noise), or with a power spectrum of index 0 (white noise), implying that the light curve is variable on timescales from days to months. The X-ray spectrum is well fitted by a power law with spectral index {\\Gamma} = 2.10 - 2.35, and we found that the spectral shape remains roughly constant as the flux changes. A constant spectral shape with respect to a change in the X-ray flux may favour a scenario in which the X-ray emission is dominated by synchrotron radiation produced in a jet.

Bernardini, Federico

2014-01-01

273

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

274

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

275

Variable speed, condensing steam turbine and power system  

Microsoft Academic Search

The variable speed condensing steam turbine is a simplified and effective steam expander which is built mainly of simple, lowcost sheet metal parts and is designed to provide a variable speed\\/torque output range. The turbine concept is based on the past tesla turbine principle of equally spaced rotor discs to provide a long helical path for steam expansion with high

1980-01-01

276

Inferring the mass of spherical stellar systems from velocity moments  

Microsoft Academic Search

The usefulness of line-of-sight velocity distributions for constraining the potential and kinematics of a nonrotating spherical system when nothing is known a priori about its radial mass distribution is discussed. A formalism, based on velocity moments, is developed in order to make use of the additional information contained within the distribution of line-of-sight velocities at every projected radius. It is

Herwig Dejonghe; David Merritt

1992-01-01

277

Automatic digital recording system for mass-spectrum extremes  

SciTech Connect

This paper describes a system for digital recording of mass-spectrum peaks with an amplitude of 0.03-100 V. The system can be used for automatic digital recording of extremal values of any dependence of voltage or current that can be measured with an electronic recorder that is located in the extremal region (plateau) for not under 0.2 sec. The circuit for selection of extremal points is connected to the controller of the reversible electric motor of the electronic recorder. A typical mass spectrum is shown obtained in analysis of the isotope composition of argon with a Ar 38 tracer and oscillograms of signals from the unbalanced amplifier and the output of the printer driver. Use of the system has shown that recording time of the argon spectrum (36-40 amu) with the GD-150 mass spectrometer is reduced by a factor of 3-4, the relative random error of determining the ratio Ar 40/Ar 36 is reduced from 2.5-4.0% to 1.5-2.0%, and the effect of recorder hysteresis on the analysis results is eliminated.

Grechishnikov, A.V.

1986-08-01

278

On inversion for mass distribution from global (time-variable) gravity field  

NASA Astrophysics Data System (ADS)

The well-known non-uniqueness of the gravitational inverse problem states that the external gravity field, even if completely and exactly known, cannot uniquely determine the density distribution of the body that produces the gravity field. 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-D the degree of knowledge deficiency in trying to inversely recover the density distribution from an external gravity field solution is ( n + 1)( n + 2)/2 - (2 n + 1) = 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 largely come from the Earth's surface over a wide range of timescales.

Chao, Benjamin F.

2005-04-01

279

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

NASA Astrophysics Data System (ADS)

The well-known non-uniqueness of the gravitational inverse problem states that the external gravity field, even if completely and exactly known, cannot uniquely determine the density distribution of the body that produces the gravity field. 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-D the degree of knowledge deficiency in trying to inversely recover the density distribution from external gravity field is (n+1)(n+2)/2 - (2n+1) = 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 largely come from the Earth's surface over a wide range of timescales.

Chao, B. F.

2004-12-01

280

A Body Shape Index and Heart Rate Variability in Healthy Indians with Low Body Mass Index  

PubMed Central

Background. One third of Indian population is said to be suffering from chronic energy deficiency (CED), with increased risk of developing chronic diseases. A new anthropometric measure called A Body Shape Index (ABSI) is said to be a better index in predicting risks for premature mortality. ABSI is also in part said to be a surrogate of visceral fat. Objective. The present study aimed to explore the association between indices of HRV (heart rate variability), BMI, WC, and ABSI in healthy Indian males with low BMI (BMI < 18.5?kg/m2) and to compare with normal BMI group (BMI 18.5 to 24.9?kg/m2). Methodology. ABSI and BMI were derived from anthropometric parameters, namely, height, weight, and waist circumference in 178 males aged 18 to 78 years. Subjects were categorized into two groups based on their BMI. Results and Conclusions. Power spectral analysis of HRV demonstrated a significant negative correlation between Log HF (high frequency) and ABSI in both low BMI [?24.2 (9.4), P < 0.05] and normal BMI group [?23.41 (10.1), P < 0.05] even after controlling for age. Thus even with slight increase in BMI among low BMI individuals, there could be a greater risk of cardiovascular morbidity and mortality. PMID:25371818

Thomas, Tinku; Bharathi, Ankalmadagu Venkatsubbareddy; Sucharita, Sambashivaiah

2014-01-01

281

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.

282

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

283

X-Ray Determination of the Variable Rate of Mass Accretion onto TW Hydrae  

NASA Astrophysics Data System (ADS)

Diagnostics of electron temperature (Te ), electron density (ne ), and hydrogen column density (N 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 10-9 M ? yr-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 H, Te , and ne 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.; Gnther, H. M.; Luna, G. J. M.; Wolk, S. J.

2012-12-01

284

X-Ray Determination of the Variable Rate of Mass Accretion onto TW Hydrae  

E-print Network

Diagnostics of electron temperature (T_e), electron density (n_e), and hydrogen column density (N_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 x 10^{-9} M_{\\odot} yr^{-1}, for a stellar magnetic field strength of 600 Gauss 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_H, T_e, and n_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 subs...

Brickhouse, N S; Dupree, A K; Gnther, H M; Luna, G J M; Wolk, S J

2012-01-01

285

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

286

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

287

The effect of including molecular opacities of variable composition on the evolution of intermediate-mass AGB stars  

NASA Astrophysics Data System (ADS)

Calculations from stellar evolutionary models of low- and intermediate-mass asymptotic giant branch (AGB) stars provide predictions of elemental abundances and yields for comparison to observations. However, there are many uncertainties that reduce the accuracy of these predictions. One such uncertainty involves the treatment of low-temperature molecular opacities that account for the surface abundance variations of C, N and O. A number of prior calculations of intermediate-mass AGB stellar models that incorporate both efficient third dredge-up and hot bottom burning include a molecular opacity treatment which does not consider the depletion of C and O due to hot bottom burning. Here we update the molecular opacity treatment and investigate the effect of this improvement on calculations of intermediate-mass AGB stellar models. We perform tests on two masses, 5 and 6 M?, and two metallicities, Z = 0.001 and 0.02, to quantify the variations between two opacity treatments. We find that several evolutionary properties (e.g. radius, Teff and Tbce) are dependent on the opacity treatment. Larger structural differences occur for the Z = 0.001 models compared to the Z = 0.02 models indicating that the opacity treatment has a more significant effect at lower metallicity. As a consequence of the structural changes, the predictions of isotopic yields are slightly affected with most isotopes experiencing changes up to 60 per cent for the Z = 0.001 models and 20 per cent for the Z = 0.02 models. Despite this moderate effect, we conclude that it is more fitting to use variable molecular opacities for models undergoing hot bottom burning.

Fishlock, C. K.; Karakas, A. I.; Stancliffe, R. J.

2014-02-01

288

VARIABILITY OF "GEOSTROPHIC MASS" IN THE PRESENCE OF A LONG BOUNDARY AND RELATED KELVIN WAVE  

E-print Network

equations on the semi-infinite f- plane from full rotating shallow water (RSW) system which is often used-dimensional RSW equations take the form x P V y U V x U U T U -=- + + , (1.1a) y P U y V V x V U T V

289

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

290

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

291

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, Franois; Correia, Alexandre C M; Laskar, Jacques; Mordasini, Christoph; Queloz, Didier; Santos, Nuno C; Udry, Stphane; Bertaux, Jean-Loup; Sivan, Jean-Pierre

2006-05-18

292

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

293

High Frequency Effects of Variable Frequency Drives (VFD) on Electrical Submersible Pump (ESP) Systems  

E-print Network

Variable frequency drives (VFD) and subsea (umbilical) cables are frequently used in electrical submersible pump (ESP) systems for offshore platforms. There are two basic system configurations for ESP systems; VFD can be installed on the platform...

Ozkentli, Esra

2012-10-19

294

Variability in the Heritability of Body Mass Index: A Systematic Review and Meta-Regression  

PubMed Central

Evidence for a major role of genetic factors in the determination of body mass index (BMI) comes from studies of related individuals. Despite consistent evidence for a heritable component of BMI, estimates of BMI heritability vary widely between studies and the reasons for this remain unclear. While some variation is natural due to differences between populations and settings, study design factors may also explain some of the heterogeneity. We performed a systematic review that identified 88 independent estimates of BMI heritability from twin studies (total 140,525 twins) and 27 estimates from family studies (42,968 family members). BMI heritability estimates from twin studies ranged from 0.47 to 0.90 (5th/50th/95th centiles: 0.58/0.75/0.87) and were generally higher than those from family studies (range: 0.240.81; 5th/50th/95th centiles: 0.25/0.46/0.68). Meta-regression of the results from twin studies showed that BMI heritability estimates were 0.07 (P?=?0.001) higher in children than in adults; estimates increased with mean age among childhood studies (+0.012/year, P?=?0.002), but decreased with mean age in adult studies (?0.002/year, P?=?0.002). Heritability estimates derived from AE twin models (which assume no contribution of shared environment) were 0.12 higher than those from ACE models (P?

Elks, Cathy E.; den Hoed, Marcel; Zhao, Jing Hua; Sharp, Stephen J.; Wareham, Nicholas J.; Loos, Ruth J. F.; Ong, Ken K.

2012-01-01

295

Flow of variably fluidized granular masses across three-dimensional terrain I. Coulomb mixture theory  

USGS Publications Warehouse

Rock avalanches, debris flows, and related phenomena consist of grain-fluid mixtures that move across three-dimensional terrain. In all these phenomena the same basic forces, govern motion, but differing mixture compositions, initial conditions, and boundary conditions yield varied dynamics and deposits. To predict motion of diverse grain-fluid masses from initiation to deposition, we develop a depth-averaged, threedimensional mathematical model that accounts explicitly for solid- and fluid-phase forces and interactions. Model input consists of initial conditions, path topography, basal and internal friction angles of solid grains, viscosity of pore fluid, mixture density, and a mixture diffusivity that controls pore pressure dissipation. Because these properties are constrained by independent measurements, the model requires little or no calibration and yields readily testable predictions. In the limit of vanishing Coulomb friction due to persistent high fluid pressure the model equations describe motion of viscous floods, and in the limit of vanishing fluid stress they describe one-phase granular avalanches. Analysis of intermediate phenomena such as debris flows and pyroclastic flows requires use of the full mixture equations, which can simulate interaction of high-friction surge fronts with more-fluid debris that follows. Special numerical methods (described in the companion paper) are necessary to solve the full equations, but exact analytical solutions of simplified equations provide critical insight. An analytical solution for translational motion of a Coulomb mixture accelerating from rest and descending a uniform slope demonstrates that steady flow can occur only asymptotically. A solution for the asymptotic limit of steady flow in a rectangular channel explains why shear may be concentrated in narrow marginal bands that border a plug of translating debris. Solutions for static equilibrium of source areas describe conditions of incipient slope instability, and other static solutions show that nonuniform distributions of pore fluid pressure produce bluntly tapered vertical profiles at the margins of deposits. Simplified equations and solutions may apply in additional situations identified by a scaling analysis. Assessment of dimensionless scaling parameters also reveals that miniature laboratory experiments poorly simulate the dynamics of full-scale flows in which fluid effects are significant. Therefore large geophysical flows can exhibit dynamics not evident at laboratory scales.

Iverson, R. M.; Denlinger, R. P.

2001-01-01

296

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

NASA Astrophysics Data System (ADS)

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 (NO3). 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 NO3 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.

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

2013-06-01

297

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

298

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

299

Methodological Problems in the Formulation and Validation of System Dynamics Models Incorporating Soft Variables  

Microsoft Academic Search

While formulating and then analyzing a system dynamics model that incorporates soft, qualitative variables, problems are encountered. First most of the variables of this kind are measured using a qua si-quantitative framework. The question of reliability and validity of such measurement needs to be addressed. Second, the causal relationships among the variables would have to be ascertained in a way

Santanu Roy

300

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

301

Research and design of high speed mass image storage system  

NASA Astrophysics Data System (ADS)

The design of the high mass image storage system is introduced using DSP, FPGA and Flash structure. Texas Instruments Corporation DSP chip (TMS320VC5509APEG) is used as the main controller, Samsung's Flash chips (K9F2G08U0M) used as the main storage medium, and the Xilinx Corporation FPGA chip (XCV600E) used as logic control modules. In this system, Storage module consists of 32 Flash memory chips, which are divided into 8 groups that correspond to 8-level pipeline. The 4-Flash memory chip forms a basic 32-bit memory module. The entire system storage space is 64 G bit. Through simulation and verification, the storage speed is up to 352Mbps and readout speed is up to 290Mbps, it can meet the demand to the high-speed access, and which has strong environmental adaptability.

Li, Yu-feng; Xue, Rong-kun; Liang, Fei

2009-07-01

302

Variability of water mass properties in the Strait of Sicily in summer period of 1998-2013  

NASA Astrophysics Data System (ADS)

The Strait of Sicily plays a crucial role in determining the water-mass exchanges and related properties between the western and eastern Mediterranean. Hydrographic measurements carried out from 1998 to 2013 allowed the identification of the main water masses present in the Strait of Sicily: a surface layer composed of Atlantic water (AW) flowing eastward, intermediate and deep layers mainly composed of Levantine intermediate water (LIW), and transitional eastern Mediterranean deep water (tEMDW) flowing in the opposite direction. Furthermore, for the first time, the signature of intermittent presence of western intermediate water (WIW) is also highlighted in the northwestern part of the study area (12.235 E, 37.705 N). The excellent area coverage allowed to highlight the high horizontal and vertical inter-annual variability affecting the study area and also to recognize the permanent character of the main mesoscale phenomena present in the surface water layer. Moreover, strong temperature-salinity correlations in the intermediate layer, for specific time intervals, seem to be linked to the reversal of surface circulation in the central Ionian Sea. The analysis of CTD data in deeper water layer indicates the presence of a large volume of tEMDW in the Strait of Sicily during the summers of 2006 and 2009.

Bonanno, A.; Placenti, F.; Basilone, G.; Mifsud, R.; Genovese, S.; Patti, B.; Di Bitetto, M.; Aronica, S.; Barra, M.; Giacalone, G.; Ferreri, R.; Fontana, I.; Buscaino, G.; Tranchida, G.; Quinci, E.; Mazzola, S.

2014-10-01

303

Decadal variability in coupled sea-ice-thermohaline circulation systems  

SciTech Connect

An interdecadal oscillation in a coupled ocean-ice system was identified in a previous study. This paper extends that study to further examine the stability of the oscillation and the sensitivity of its frequency to various parameters and forcing fields. Three models are used: (i) an analytical box model; (ii) a two-dimensional model for the ocean thermohaline circulation (THC) coupled to a thermodynamic ice model, as in the authors` previous study; and (iii) a three-dimensional ocean general circulation model (OGCM) coupled to a similar ice model. The box model is used to elucidate the essential feedbacks that give rise to this oscillation and to identify the most important parameters and processes that determine the period. The counted model becomes more stable toward low coupling, greater diffusion, and weaker THC feedback. Nonlinear effects in the sea-ice model become important in the higher ocean-ice coupling regime where the effective sea-ice damping associated with this nonlinearity stabilizes the model. The 3D OGCM is used to test this coupled ocean-ice mechanism in a more realistic model setting. This model generates an interdecadal oscillation whose characteristics and phase relations among the model variables are similar to the oscillation obtained in the 2D models. The major difference is that the oscillation frequency is considerably lower. The difference can be explained in terms of the analytical box model solution in which the period of oscillation depends on the rate of anomalous density production by melting/cooling of sea ice per SST anomaly, times the rate of warming/cooling by anomalous THC heat advection per change in density anomaly. The 3D model has a smaller THC response to high-latitude density perturbations than the 2D model, and anomalous velocities in the 3D case tend to follow the mean isotherms so anomalous heat advection is reduced. This slows the ocean-ice feedback process, leading to the longer oscillation period. 36 refs., 27 figs.

Yang, J. [Woods Hole Oceanographic Institution, Woods Hole, MA (United States)] [Woods Hole Oceanographic Institution, Woods Hole, MA (United States); Neelin, J.D. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States)

1997-12-01

304

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

305

Observational dynamics of low-mass stellar systems  

E-print Network

The last fifteen years have seen the discovery of new types of low-mass stellar systems that bridge the gap between the once well-separated regimes of galaxies and of star clusters. Whether such objects are considered galaxies depends also on the definition of the term "galaxy", and several possible criteria are based on their internal dynamics (e.g. the common concept that galaxies contain dark matter). Moreover, studying the internal dynamics of low-mass stellar systems may also help understand their origin and evolutionary history. The focus of this paper is on two classes of stellar systems at the interface between star clusters and dwarf galaxies: ultra-compact dwarf galaxies (UCDs) and diffuse Galactic globular clusters (GCs). A review of our current knowledge on the properties of UCDs is provided and dynamical considerations applying to diffuse GCs are introduced. In the following, recent observational results on the internal dynamics of individual UCDs and diffuse Galactic globular clusters are presen...

Frank, Matthias J

2014-01-01

306

THE EVOLUTION OF PLANETARY SYSTEMS WITH TIME-DEPENDENT STELLAR MASS LOSS RATES  

E-print Network

THE EVOLUTION OF PLANETARY SYSTEMS WITH TIME-DEPENDENT STELLAR MASS LOSS RATES Kassandra R systems, this paper generalizes previous studies of orbital evolution in planetary systems with stellar rates, we consider single planet systems where the stellar mass loss rate is time depen- dent; the mass

Bloch, Anthony

307

Systems/Circuits Strong Correlations between Sensitivity and Variability Give  

E-print Network

afferent populations to provide our sense of linear motion and provide unexpected insight into the influence of variability on sensory encoding. Introduction As we navigate through the world, our brain other senses. To do so, we recorded single otolith afferent activity in macaque monkeys during linear

Chacron, Maurice

308

Variable Angle Locking Intercarpal Fusion System for Four-Corner Arthrodesis: Indications and Surgical Technique  

PubMed Central

Four-corner fusion (4CF) is an accepted and regularly performed procedure when managing posttraumatic degenerative disorders in the wrist. This procedure consists of excision of the entire scaphoid in association with midcarpal fusion of the remaining four ulnar carpal bones (hamate, capitate, lunate, and triquetrum). In the majority of cases, the long-term outcome is a functional painless wrist. However, the exact procedure to best achieve a rapid solid bone union of the fusion mass without hardware complications remains controversial. The authors have developed a precise system to ensure precise positioning, firm fixation, and fusion at the midcarpal joint together with an early postoperative recovery, avoiding some of the issues reported with other implants used for 4CF. The described implant is a circular plate accommodating variable angle locking screws as well as compression screws that can firmly fix the plate to the carpal bones. The locking technology produces a very solid construct. A special reaming-distraction-compression guide has also been developed to both countersink the plate on the underlying carpal bone mass and allow distraction of the midcarpal joint for debridement and cancellous bone graft interposition. The features of the implant, its surgical technique, and a relevant case are described. PMID:23904983

Gonzlez del Pino, Juan; Campbell, Douglas; Fischer, Thomas; Vzquez, Fiesky Nez; Jupiter, Jesse B.; Nagy, Ladislav

2012-01-01

309

Mass, Energy, Space And Time Systemic Theory---MEST  

NASA Astrophysics Data System (ADS)

Things have their physical system of the mass, energy, space and time of themselves-MEST. The matter have the physical systemic moel like that the mass-energy is center and the space-time is around. The time is from the frequency of wave, the space is from the amplitude of wave. What is the physical effection of the wave. The gravity and inertial force is from the wave. Not only the planets have the mass and the kinetic energy, but also it have the wave and the wave energy. According to the equivalence principle of the general relativity, there is the equation: ma=mg and mv^2 /2= ?mc^2. The energy equation of the planets: E=mv^2=mgr (v is velocity) be bring put forward. In quantum mechanics, according to the quantum light theory and the de Broglie's theory , there are the equation of the wave: E=h?, p=h/? (h is Planck constant, p is momentum, ? is the wavelengh), and there is the equation of the wave: E=mc^2. So the energy equation of the planets: E=mv^2 = mv^2 /2 + ?mc^2 (mv^2 /2= ?mc^2 ) be bring put forward. The equation: ?mc^2 show that the planets have the wave of itself, and the wave give the planets the energy. So it do not fall from the heaven. When the matter go into the heaven, it need get the wave energy (like the potential energy). So we can make a new light-flight with the light-driving force.

Cao, Dayong

2010-03-01

310

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

311

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.

312

Computer-Aided Diagnostic System For Mass Survey Chest Images  

NASA Astrophysics Data System (ADS)

In order to support screening of chest radiographs on mass survey, a computer-aided diagnostic system that automatically detects abnormality of candidate images using a digital image analysis technique has been developed. Extracting boundary lines of lung fields and examining their shapes allowed various kind of abnormalities to be detected. Correction and expansion were facilitated by describing the system control, image analysis control and judgement of abnormality in the rule type programing language. In the experiments using typical samples of student's radiograms, good results were obtained for the detection of abnormal shape of lung field, cardiac hypertrophy and scoliosis. As for the detection of diaphragmatic abnormality, relatively good results were obtained but further improvements will be necessary.

Yasuda, Yoshizumi; Kinoshita, Yasuhiro; Emori, Yasufumi; Yoshimura, Hitoshi

1988-06-01

313

Variable Rate Variable Power MIMO System for Integrated Voice and Data Services  

Microsoft Academic Search

We propose an adaptive rate and power allocation algorithm for integrated voice and data services in a multiple input multiple output (MIMO) system. Given the available power at the MIMO transmitter is limited, the voice service is given the highest priority and appropriate power is allocated to satisfy the bit error rate (BER) requirement for voice transmission. Based on the

Lay Teen Ong; Sangarapillai Lambotharan

2006-01-01

314

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

315

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

E-print Network

Tidally-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 of numerical models to explore the effects of tidal loading on aqueous fluid flow within mid-ocean ridge

Crone, Timothy J.

316

Energy Efficient Control of a Boosting System with Multiple Variable-Speed Pumps in Parallel  

E-print Network

to this structural process optimization problem in [12]. Due to the concerned problem is not convex [2], therebyEnergy Efficient Control of a Boosting System with Multiple Variable-Speed Pumps in Parallel Zhenyu with multiple variable-speed pumps in parallel is to minimize the pump system energy consumption by control

Yang, Zhenyu

317

System parameters and measurement instrument parameters are not separately observable: Relational mass is observable while absolute mass is not  

E-print Network

A brief summary of the objections to the relational nature of inertial mass, gravitational mass and electric charge is presented. The objections are refuted by showing that the measurement process of comparing an instrument reference clock and a reference rod both obeying the laws of physics to a system obeying the same laws of physics results in relational quantities: inertial mass, gravitational mass and electric charge appear only as ratios. This means that scaling of the absolute inertial mass of every object in the universe by the same factor is unobservable (likewise for gravitational mass and electric charge). It is shown that the measurement process does not separate the instrument parameters from the system parameters. Instead a measurement produces functions of fundamental, dimensionless parameters such as the fine structure constant, electron-proton mass ratio and the proton gyro-magnetic factor. It is shown that the measurement of Planck's constant also results in such a function of these dimensionless parameters. Application of this analysis to the "absolute" Planck units shows that they too are functions only of relational quantities. Analysis focuses initially on non-relativistic systems for the sake of clarity and simplicity. The results are then extended to relativistic systems described by the Dirac equation and the Einstein field equations of general relativity. The results support the assertion that instrument parameters cannot be separated from system parameters even in classical mechanics.

Craig R. Holt

2014-06-19

318

Oscillations and variability in the p53 system  

Microsoft Academic Search

Understanding the dynamics and variability of protein circuitry requires accurate measurements in living cells as well as theoretical models. To address this, we employed one of the best-studied protein circuits in human cells, the negative feedback loop between the tumor suppressor p53 and the oncogene Mdm2. We measured the dynamics of fluorescently tagged p53 and Mdm2 over several days in

Naama Geva-Zatorsky; Nitzan Rosenfeld; Shalev Itzkovitz; Ron Milo; Alex Sigal; Erez Dekel; Talia Yarnitzky; Yuvalal Liron; Paz Polak; Galit Lahav; Uri Alon

2006-01-01

319

Vibration control of two degrees of freedom system using variable inertia vibration absorbers: Modeling and simulation  

NASA Astrophysics Data System (ADS)

Variable inertia vibration absorbers (VIVA) are previously used for the vibration control of single degree of freedom (dof) primary systems. The performance of such absorbers is studied in many investigations. This paper presents the dynamic modeling and simulation of a proposed modified design of such VIVA's for the vibration control of two dof primary systems. Lagrange formulation is used to obtain its dynamic model in an analytical form. This model, which is highly nonlinear, is used to develop a computational algorithm to study the absorber performance characteristics. This algorithm is programmed and simulated in Matlab. The obtained results are numerically verified using SAMS2000 software. The effect of mass and stiffness of the proposed VIVA on its performance and tuning is discussed. An optimization algorithm is developed to select the best absorber parameters for vibration suppression of a specific primary system. The obtained results show a good agreement with those obtained using similar techniques. In addition, a linearized model of VIVA dynamics is developed, tested and simulated for the same data used in its nonlinear model. The relative deviation between results of the linear and nonlinear models is less than 1%, which confirms the realistic use of this linearized model. The experimental testing and verification of the simulation results of the proposed VIVA is the subject of another paper.

Megahed, S. M.; Abd El-Razik, A. Kh.

2010-11-01

320

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

321

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

322

Variable Speed Drive (VSD) Applications in Dual-Duct Constant Volume Systems  

E-print Network

Models have been developed for static pressure and potential supply fan energy savings by using variable speed drive (VSD) in dual-duct constant volume systems. Experiments have been performed using a full size dual-duct constant volume system...

Joo, I.; Liu, M.; Conger, K.; Wang, G.

2002-01-01

323

A precise HST parallax of the cataclysmic variable EX Hydrae, its system parameters, and accretion rate  

E-print Network

Using the HST Fine Guidance Sensor, we have measured a high precision astrometric parallax of the cataclysmic variable EX Hydrae, pi=15.50+-0.29mas. From the wavelength-integrated accretion-induced energy flux, we derive a quiescent accretion luminosity for EX Hya of Lacc = (2.6+-0.6)x10e32 erg. The quiescent accretion rate then is Mdot=(6.2\\+-1.5)x10e-11 (M1/0.5Msun)^(-1.61})Msun/yr. The time-averaged accretion rate, which includes a small correction for the rare outbursts, is 6% higher. We discuss the system parameters of EX Hya and deduce M1=0.4-0.7Msun, M2=0.07-0.10Msun, and i=76.0deg-77.6deg, using recent radial velocity measurements of both components and restrictions imposed by other observational and theoretical constraints. We conclude that the secondary is undermassive, overluminous, and expanded over a ZAMS star of the same mass. Near the upper limit to M1, the accretion rate of the white dwarf coincides with that due to near-equilibrium angular momentum loss by gravitational radiation and angular momentum transfer from the orbit into the spin-up of the white dwarf. Near the lower mass limit, the correspondingly higher accretion rate requires that either an additional angular momentum loss process is acting besides gravitational radiation or that accretion occurs on a near-adiabatic time scale. The latter possibility would imply that EX Hya is in a transient phase of high mass transfer and the associated spin-up of the white dwarf.

K. Beuermann; Th. E. Harrison; B. E. McArthur; G. F. Benedict; B. T. Gaensicke

2003-09-19

324

Chemical reaction and variable viscosity effects on flow andmass transfer of a non-Newtonian visco-elastic fluid past astretching surface embedded in a porous medium  

Microsoft Academic Search

This work deals with the study of the boundary layer flow and mass transfer of a visco-elastic fluid immersed in a porous\\u000a medium over a stretching surface in the presence of surface slip, chemical reaction and variable viscosity. The partial differential\\u000a equations governing the flow have been transformed by similarity transformation into a system of coupled nonlinear ordinary\\u000a differential equations

Mostafa A. A. Mahmoud

2010-01-01

325

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

326

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

327

Analysis of two-element zoom systems based on variable power lenses.  

PubMed

Traditional optical systems with variable optical characteristics are composed of several optical elements that can be shifted with respect to each other mechanically. A motorized change of position of individual elements (or group of elements) then makes possible to achieve desired optical properties of such zoom lens systems. A disadvantage of such systems is the fact that individual elements of these optical systems have to move very precisely, which results in high requirements on mechanical construction of such optical systems. Our work is focused on a paraxial and third order aberration analysis of possible optical designs of two-element zoom lens systems based on variable power lenses with a variable focal length. First order chromatic aberrations of the variable power lenses are also described. Computer simulation examples are presented to show that such zoom lens systems without motorized movements of lenses appear to be promising for the next-generation of zoom lens design. PMID:20389699

Miks, Antonin; Novak, Jiri

2010-03-29

328

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 frequencydisturbance 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

329

Orbits and masses in the multiple system LHS 1070  

NASA Astrophysics Data System (ADS)

Aims: We present a study of the orbits of the triple system LHS 1070, with the aim to determine individual masses of its components. Methods: Sixteen new relative astrometric positions of the three components in the K band were obtained with NACO at the VLT, Omega CASS at the 3.5 m telescope on Calar Alto, and other high-spatial-resolution instruments. We combined them with data from the literature and fit orbit models to the dataset. We derived an improved fit for the orbit of LHS 1070 B and C around each other, and an estimate for the orbit of B and C around A. Results: The orbits are nearly coplanar, with a misalignment angle of less than 10. The masses of the three components are MA = 0.13...0.16 M?, MB = 0.077 0.005 M?, and MC = 0.071 0.004 M?. Therefore, LHS 1070 C is certainly, and LHS 1070 B probably a brown dwarf. Comparison with theoretical isochrones shows that LHS 1070 A is either fainter or more massive than expected. One possible explanation would be that it is a binary. However, the close companion reported previously could not be confirmed. Based on observations collected at the European Southern Observatory, Chile, proposals number 60.A-9026, 66.C-0219, 67.C-0354, 68.C-0539, 70.C-0476, 072.C-0022, 074.C-0637, 078.C-0386, 380.C-0179, 382.C-0324, and 382.C-0329.

Khler, R.; Ratzka, T.; Leinert, Ch.

2012-05-01

330

Intermolecular Interactions in Biomolecular Systems Examined by Mass Spectrometry  

NASA Astrophysics Data System (ADS)

With the development of electrospray and matrix-assisted laser desorption ionization, mass spectrometry (MS) evolved into a powerful tool in the field of biochemistry. Whereas MS is primarily analytical in nature, an increasing number of MS research groups employ the method to address fundamental biochemical questions. Probing the interaction of noncovalently bound molecules in the mass spectrometer is one of the most interesting MS-based experiments possible today, with the potential of making a significant contribution to the basic understanding of the structure and function of biochemical complexes. Here we review a number of current research efforts employing primarily MS techniques to investigate intermolecular interactions in biochemical systems. Examples chosen include the interaction of biomolecules with solvent molecules; interactions between nucleic-acid molecules, in particular, interactions in duplex and quadruplex structures; and interactions between proteins involved in neurodegenerative diseases. Finally we conclude by presenting a few examples of very large biomolecular assemblies in the mega-Dalton range analyzed by MS.

Wyttenbach, Thomas; Bowers, Michael T.

2007-05-01

331

Early Pleistocene short-term intermediate water mass variability influences Carbonate Mound development in the NE Atlantic (IODP Site 1317)  

NASA Astrophysics Data System (ADS)

The Integrated Ocean Drilling Program (IODP) Exp. 307 drilled the 155 m high Challenger Mound in the Porcupine Seabight (SW off Ireland) in order to investigate for the first time sediments from the base of a giant carbonate mound. In this study we focus on sediments from the base of Challenger Mound (Porcupine Seabight, SW off Ireland) IODP Site 1317 in high resolution. The mound initiation and start-up phase coincides with the intensification of the Northern Hemisphere Glaciation (INHG) at around 2.6 Ma. Further carbonate mound development seems to be strongly dependent on rapid changes in paleoceanographic and climatic conditions at the Pliocene-Pleistocene boundary, especially characterized and caused by the interaction of intermediate water masses, the Mediterranean Outflow Water (MOW), the Eastern North Atlantic Water (ENAW) and the influence of Southern Component Water (SCW). This study is based on well-established proxies such as ?18O and ?13C of planktonic (Globigerina bulloides) and benthic foraminifera (Fontbotia wuellerstorfi, Discanomalina coronata, Lobatula lobatula, Lobatula antarctica, and Planulina ariminensis) as well as grain size parameters to identify the paleoenvironmental and paleoecological setting favourable for the initial coral colonization on the mound. Stable oxygen and carbon isotope records of benthic foraminiferal species indicate that L. lobatula provides a reliable isotopic signature for paleoenvironmental reconstructions. In particular, ?18O values of L. lobatula indicate initial mound growth started in a glacial mode with moderate excursions in ?18O values. Bottom water temperatures, calculated using standard equations based on ?18O of foraminiferal tests, range between 7 and 11C, consistent with the known temperature range conducive for cold-water coral growth and development. Bottom currents transporting intermediate water masses of southern origin (Mediterranean, Bay of Biscay) enhanced at 2.6 Ma supporting first coral settlements with the INHG. The benthic ?13C and the sortable silt records indicate that the early Pleistocene hydrodynamic regime was characterized by weaker current intensities associated with vertical movements of MOW or its replacement by SCW at intermediate depth. After these sluggish phases enhanced MOW flow dominated again and led to stronger current intensities and most probably sediment erosion on Challenger Mound. Erosion in combination with early diagenetic (oxidation) processes overprinted the sediment layers as indicated by dissolved coral skeletons, the increase in Ca-content and sediment density, minimum ?13Cplanktonic values, as well as the occurrence of gypsum and pyrite, implying a careful evaluation of original and overprinted geochemical signals. We conclude that the Challenger Mound development was already influenced by short-term variability of water masses from southern origin and possible erosional events comparable to the late Pleistocene setting.

Raddatz, J.; Rggeberg, A.; Margreth, S.; Liebetrau, V.; Dullo, W.; Eisenhauer, A.; Iodp Expedition 307 Scientific Party

2010-12-01

332

A Variable Ultraluminous Supersoft X-ray Source in "The Antennae": Stellar-Mass Black Hole or White Dwarf?  

E-print Network

The chandra monitoring observations of The Antennae (NGC 4038/39) have led to the discovery of a variable, luminous, supersoft source (SSS). This source is only detected at energies below 2 keV and, in 2002 May, reached count rates comparable to those of the nine ultraluminous X-ray sources (ULXs) detected in these galaxies. Spectral fits of the SSS data give acceptable results only for a $\\sim$100--90 eV blackbody spectrum with an intrinsic absorption column of $N_{\\rm H} \\sim 2-3 \\times 10^{21} \\rm cm^{-2}$. For a distance of 19 Mpc, the best-fit observed luminosity increases from 1.7$\\times 10^{38}$\\ergs in 1999 December to 8.0$\\times 10^{38}$\\ergs in 2002 May. The intrinsic, absorption-corrected best-fit luminosity reaches 1.4$\\times 10^{40}$ \\ergs in 2002 May. The assumption of unbeamed emission would suggest a black hole of $\\ga$100\\msun. However, if the emission is blackbody at all times, as suggested by the steep soft spectrum, the radiating area would have to vary by a factor of $\\sim10^3$, inconsistent with gravitational energy release from within a few Schwarzschild radii of a black hole. Viable explanations for the observed properties of the SSS are provided by anisotropic emission from either an accreting nuclear-burning white dwarf or an accreting stellar-mass black hole.

G. Fabbiano; A. R. King; A. Zezas; T. J. Ponman; A. Rots; Francois Schweizer

2003-04-30

333

Vibrating systems with singular mass-inertia matrices  

SciTech Connect

Vibrating systems with singular mass-inertia matrices arise in recent continuum models of Smart Structures (beams with PZT strips) in assessing the damping attainable with rate feedback. While they do not quite yield {open_quotes}distributed{close_quotes} controls, we show that they can provide a fixed nonzero lower bound for the damping coefficient at all mode frequencies. The mathematical machinery for modelling the motion involves the theory of Semigroups of Operators. We consider a Timoshenko model for torsion only - a {open_quote}smart string,{close_quotes} where the damping coefficient turns out to be a constant at all frequencies. We also observe that the damping increases initially with the feedback gain but decreases to zero eventually as the gain increases without limit, above a critical value. At the critical value the energy decreases to zero in finite time - the semigroup is superstable, and there are no modes.

Balakrishnan, A.V.

1994-12-31

334

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

335

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

336

Development and characterization of a variable turbulence generation system  

Microsoft Academic Search

Experimental turbulent combustion studies require systems that can simulate the turbulence intensities [u?\\/U\\u000a 0~2030% (Koutmos and McGuirk in Exp Fluids 7(5):344354, 1989)] and operating conditions of real systems. Furthermore, it is important to have systems where turbulence intensity can be\\u000a varied independently of mean flow velocity, as quantities such as turbulent flame speed and turbulent flame brush thickness\\u000a exhibit complex

A. Marshall; P. Venkateswaran; D. Noble; J. Seitzman; T. Lieuwen

2011-01-01

337

A very high performance stabilization system for large mass bolometerexperiments  

NASA Astrophysics Data System (ADS)

CUORE is a large mass bolometric experiment, composed of 988 crystals, under construction in Hall A of the Gran Sasso Underground Laboratories (LNGS). Its main aim is the study of neutrinoless double beta decay of 130Te. Each bolometer is a 760 g crystal of Tellurium dioxide on which a Nuclear Transmutation Doped Ge thermistor, Ge NTD, is glued with proper thermal contact. The stability of the system is mandatory over many years of data taking. To accomplish this requirement a heating resistor is glued on each detector across which a voltage pulse can be injected at will, to develop a known calibrated heating power. We present the design solution for a pulse generator system to be used for the injection of such a small and short voltage pulse across the heaters. This system is composed by different custom PCB boards each of them having multi-channel independent outputs completely remotely programmable from the acquisition system, in pulse width and amplitude, through an on-board ARM7 microcontroller. Pulse amplitudes must be selectable, in order to handle each detector on its full dynamic range. The resolution of the output voltage is 12 bits over 10 V range. An additional 4 steps programmable voltage attenuator is added at every output. The width of any pulse can range from 100 ?s to 25.5 ms. The main features of the final system are: stability and precision in pulses generation (at the level of less than a ppm/C), low cost (thanks to the use of commercial components) and compact implementation.

Arnaboldi, C.; Giachero, A.; Gotti, C.; Pessina, G.

2011-10-01

338

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

339

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

340

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  

NASA Astrophysics Data System (ADS)

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 coarse-sand 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 down wind 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, Dale A.; Fryrear, D. W.; Xiao, Jing Bing; Stockton, Paul; Ono, Duane; Helm, Paula J.; Gill, Thomas E.; Ley, Trevor

1997-11-01

341

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

342

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

343

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

344

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

345

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...

346

General treatment of optical forces and potentials in mechanically variable photonic systems.  

PubMed

We present an analytical formalism for the treatment of the forces and potentials induced by light in mechanically variable photonic systems (or optomechanically variable systems) consisting of linear media. Through energy and photon-number conservation, we show that knowledge of the phase and the amplitude response of an optomechanically variable system, and its dependence on the mechanical coordinate of interest, is sufficient to compute the forces produced by light. This formalism not only offers a simple analytical alternative to computationally intensive Maxwell stress-tensor methods, but also greatly simplifies the analysis of mechanically variable photonic systems driven by multiple external laser sources. Furthermore, we show, through this formalism, that a scalar optical potential can be derived in terms of the phase and amplitude response of an arbitrary optomechanically variable one-port system and in generalized optomechanically variable multi-port systems, provided that their optical response is variable through a single mechanical degree of freedom. With these simplifications, well-established theories of optical filter synthesis could be extended to allow for the synthesis of complex optical force and potential profiles, independent of the construction of the underlying device or its field distribution. PMID:19907602

Rakich, Peter T; Popovi?, Milos A; Wang, Zheng

2009-09-28

347

Identifying Faults in the Variable Geometry System of a Gas Turbine Compressor  

Microsoft Academic Search

The influence of faults in the variable geometry (variable stator vanes) system of a multistage axial compressor, on the performance of an industrial gas turbine is investigated. An experimental investigation has been conducted, by implanting such faults into an operating gas turbine. The faults examined are individual stator vane mistuning of different magnitude, and located at different stages.

A. Tsalavoutas; K. Mathioudakis; A. Stamatis; M. Smith

2001-01-01

348

Overview of the Use of Natural Variability Concepts in Managing Ecological Systems  

Microsoft Academic Search

Natural resource managers have used natural variability concepts since the early 1960s and are increasingly relying on these concepts to maintain biological diversity, to restore ecosystems that have been severely altered, and as benchmarks for assessing anthropogenic change. Management use of natural variability relies on two concepts: that past conditions and processes provide context and guidance for managing ecological systems

Peter B. Landres; Penelope Morgan; Frederick J. Swanson

1999-01-01

349

A Method to Study the Effect of Renewable Resource Variability on Power System Dynamics  

E-print Network

1 A Method to Study the Effect of Renewable Resource Variability on Power System Dynamics Yu reliance on renewable resources, such as wind or solar. It is well known that the integration proposes a set-theoretic method to assess the effect of variability associated with renewable-based elec

Liberzon, Daniel

350

Mixed Variable Optimization of the Number and Composition of Heat Intercepts in a Thermal Insulation System  

Microsoft Academic Search

In the literature, thermal insulation systems with a fixed number of heat intercepts have been optimized with respect to intercept locations and temperatures. The number of intercepts and the types of insulators that surround them were chosen by parametric studies. This was because the optimization methods used could not treat such categorical variables. Discrete optimization variables are categorical if the

Michael Kokkolaras; Charles Audet; J. E. Dennis

2001-01-01

351

Chaotic linear system solvers in a variable-grain data-driven multiprocessor system  

SciTech Connect

Linear systems are important problems in many scientific applications. While asynchronous methods are effective solutions to linear systems, they are difficult to realize due to the chaotic behavior of the algorithms. In this paper, we investigate the implementation as well as the performance of an asynchronous method, namely chaotic relaxation, in our Variable-grain TaggedToken Data-flow (VTD) System. We compare asynchronous methods with synchronous methods executed on both the fine-grain and the coarse-grain execution models. New high-level dataflow language constructs axe introduced in order to express asynchronous operations. A new firing rule that deviates from the single assignment rule of functional languages is proposed to support the implementation of asynchronous computations in the VTD system. In addition to the conventional speedup measure, we then define new performance measurements, called Growth Factor, Scalability Factor, and Robustness to characterize the system performance from the machine and application viewpoints. Simulation results indicate that asynchronous methods axe more efficient than synchronous methods and that the coarse-grain execution mode is more efficient that the fine-grain execution mode in our VTD system.

Gaudiot, J.L.; Lin, Chih-Ming

1991-12-31

352

Extending the Interdisciplinary Interfaces of Geomorphology by Changing the Units of Key Variables: From Volumes to Masses to Areas  

NASA Astrophysics Data System (ADS)

When deciphering the history and future of landscape morphology, we focus on the evolution of ground surface elevation. A convenient unit to study this particular problem is the volume per area per time, which is often the unit that is used to present physical and total denudation rates. This unit, however, needs to be combined with the bulk density of rocks, sediments, and soils when the question is directed to the processes affecting the compositions of these materials that are involved in morphologic evolution of landscapes. Most notably, chemical weathering belongs to this group of processes. Though often ignored, the unit conversion from the elevation to mass changes also reveals the volumetric changes associated with chemical weathering (e.g., collapse or dilation). This is because significant differences in the bulk densities of soils, sediments, saprolites, and bedrocks can occur in association with chemical weathering and physical disturbance. Therefore, connecting the ground surface elevation changes to the volumetric changes of weathering profiles may help us better understand the production of porosities and fractures in weathering profiles, which are in turn critical controls over water pathways and residence time. Furthermore, the morphologic evolution of landscapes could be appreciated from the perspective of the soils mineral surface reactivity, when we follow the evolution of minerals specific surface area as the minerals transit from their bedrock sources, becoming part of an upland soil, moving downslope into depositional lands, and eventually entering a fluvial networks that link the lands with ocean. In other words, minerals reactivity to the surrounding geochemical environments and the minerals capacity to complex organic matter on their surface may significantly depend on their transport processes and pathways (ie., geomorphic processes). Therefore, some of the challenges in integrating geomorphology with its sister disciplines such as (bio)geochemistry, environmental chemistry, hydrology, and carbon cycle could be well characterized in the efforts to convert the units of key variables from volumes to masses to surface areas. To illustrate this proposal, we present data from the actively eroding hillslopes in the Feather River, Sierra Nevada, CA, Piedmont soils from PA, and forest soils in northern Minnesota.

Yoo, K.; Aufdenkampe, A. K.; Weinman, B. A.; Mudd, S. M.; Chen, C.

2010-12-01

353

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 10241024. 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

354

The mass, energy, space and time system of Wave, Particle and universe -MEST  

Microsoft Academic Search

Things have their own system of mass, energy, space and time of themself. (The MEST for short thereinafter). Mass is density, energy is force, time is frequency, spac is amplitude square. New mass-energy wave equation, space-time particle equation are being put forward. Mass, Energy, Space (Radius), Time (Period) of nine planes compose a MEST of plane; Mass(Density of sun), Energy

Dayong Cao

2008-01-01

355

Probing orientation of immobilized humanized anti-lysozyme variable fragment by time-of-flight secondary-ion mass spectrometry  

PubMed Central

As methods to orient proteins are conceived, techniques must also be developed that provide an accurate characterization of immobilized protein orientation. In this study, x-ray photoelectron spectroscopy (XPS), surface plasmon resonance, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to probe the orientation of a surface immobilized variant of the humanized anti-lysozyme variable fragment (HuLys Fv, 26kDa). This protein contained both a his-tag and a cysteine residue, introduced at opposite ends of the HuLys Fv, for immobilization onto nitrilotriacetic acid (NTA) and maleimide oligo(ethylene glycol) (MEG) terminated substrates, respectively. The thiol group on the cysteine residue selectively binds to the MEG groups, while the his-tag selectively binds to the Ni loaded NTA groups. XPS was used to monitor protein coverage on both surfaces by following the change in the nitrogen atomic %. SPR results showed a 10-fold difference in lysozyme binding between the two different HuLys Fv orientations. The ToF-SIMS data provided a clear differentiation between the two samples due to the intensity differences of secondary ions originating from asymmetrically located amino acids in HuLys Fv (Histidine: 81, 82, and 110 m/z; Phenylalanine: 120 and 131 m/z). An intensity ratio of the secondary-ion peaks from the histidine and phenylalanine residues at either end of the protein was then calculated directly from the ToF-SIMS data. The 45% change in this ratio, observed between the NTA and MEG substrates with similar HuLys Fv surface coverages, indicates the HuLys Fv fragment has opposite orientations on the two different surfaces. PMID:21308984

Baio, J. E.; Cheng, Fang; Ratner, Daniel M.; Stayton, Patrick S.; Castner, David G.

2011-01-01

356

Generalized framework for robust design of tuned mass damper systems  

NASA Astrophysics Data System (ADS)

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 adopt methods and concepts from the robust control literature, including: (1) the linear fractional transformation (LFT) formulation pertaining to the structured singular value ( ?) framework; (2) the concept of weighted multi-input multi-output (MIMO) norms for characterizing performance; and (3) a worst-case performance assessment method to avoid the unacceptable computation burden involved with exhaustive search or Monte Carlo methods in the presence of multiple uncertainties. Based on these, the robust design framework is organized into four steps: (1) modeling and casting the overall dynamics into the proposed LFT framework that isolates the TMD system as the controller, and the uncertainties as a structured perturbation to the nominal dynamics; (2) setting up the optimization problem based on generalized indices of nominal performance, robustness, and worst-case performance; (3) implementing a genetic algorithm (GA) for solution of the optimization problem; and (4) post-processing the results for systematic visualization, validation, and selection of preferred designs. This strategy has been implemented on several illustrative design examples involving a seismically excited multi-story building with different combinations of assumptions on the uncertainty, TMD configuration, excitation scenarios, and performance criteria. The resulting solution sets have been studied through various post-processing methods, including visualization of Pareto fronts, uncertain frequency response plots, time-domain simulations, and random vibration analysis.

Mohtat, Arash; Dehghan-Niri, Ehsan

2011-02-01

357

Burner Designs and Controls for Variable Air Preheat Systems  

E-print Network

savings relating to the use of recuperation and various types of fuel/air ratio systems will also be discus sed. Fuel costs have risen up to 750/0 over the last 12 to efficiency and reduced fuel consumption. 18 months. These accelerating fuel costs... savings relating to the use of recuperation and various types of fuel/air ratio systems will also be discus sed. Fuel costs have risen up to 750/0 over the last 12 to efficiency and reduced fuel consumption. 18 months. These accelerating fuel costs...

Lied, C. R.

1981-01-01

358

The MUSCLES Treasury Survey: Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems  

NASA Astrophysics Data System (ADS)

It has recently been discovered that 10 - 50% of M dwarfs host Earth-size planets in their habitable zones. Furthermore, the nearest potentially habitable super-Earths orbit M dwarfs, meaning that these systems likely represent our best chance to discover habitable worlds in the coming decade. The ultraviolet (UV) spectrum incident upon Earth-like planets drives the dissociation of water and CO2, the production of O2 and ozone, and may determine their ultimate habitability. At present, we lack the observational and theoretical basis to predict the energetic radiation spectrum (X-ray through UV) of an M dwarf. UV variability of low-mass exoplanet host stars, in particular the possibly sterilizing effect of flare activity, is almost completely unexplored observationally. This proposal aims to acquire the critical UV observations of low-mass host stars now, providing a treasury database for studies of exemplary nearby exoplanetary systems and potentially habitable worlds not yet discovered. Building on our successful pilot program of spectrally and temporally resolved UV radiation fields, we propose the MUSCLES Treasury Survey: a UV survey of nearby low-mass exoplanetary host stars. Using HST-COS and STIS, we will observe the 1150 - 5700A fluxes, reconstruct the important Ly-alpha emission lines, and use these data to estimate the extreme-UV (200 - 912A) irradiances incident upon exoplanetary atmospheres. The UV data will be complemented with contemporaneous X-ray and ground-based observations as well as new M dwarf atmosphere models to constrain atmospheric heating rates and provide a baseline for long-term ground-based studies of these systems.

France, Kevin

2014-10-01

359

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 USCs Women in Science and Engineering (WiSE) program is greatly appreciated.

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

2014-01-01

360

Automatic variable ventilation control systems based on air quality detection  

Microsoft Academic Search

Mechanical ventilation systems usually provide a fixed quantity of fresh air to a building space based upon the maximum number of people expected to occupy that particular space. When the use of a building space is below its design maximum, the amount of outside air brought into that space can be reduced, thus generally also reducing energy consumption through lower

I. Turiel; C. D. Hollowell; B. E. Thurston

1979-01-01

361

On estimation of unknown state variables in wastewater systems  

Microsoft Academic Search

This paper focuses on the estimation of the non-measurable physical states of wastewater systems when nonlinear models with uncertainties describe the processes. The activated sludge process (ASP), as the most commonly applied biological wastewater purification technique, attracts a great deal of attention from the research community. We developed for this class of processes a state dependent differential Riccati filter (SDDRF)

A. Iratni; R. Katebi; R. Vilanova; M. Mostefai

2009-01-01

362

Entanglement, Purity, and Information Entropies in Continuous Variable Systems  

Microsoft Academic Search

Quantum entanglement of pure states of a bipartite system is defined as the amount of local or marginal (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

Gerardo Adesso; Alessio Serafini; Fabrizio Illuminati

2005-01-01

363

Quantifying the Variable Effects of Systems with Demand Response Resources  

E-print Network

implementation of demand- side activities and created a new class of consumers, called de- mand response to the test system. I. INTRODUCTION The push towards sustainability, increasing electricity prices par- ticipation of the consumers in the North American electricity markets [1]. Such efforts have lead

Gross, George

364

Analysis and Simulation of Mechanical Trains Driven by Variable Frequency Drive Systems  

E-print Network

Induction motors and Variable Frequency Drives (VFDs) are widely used in industry to drive machinery trains. However, some mechanical trains driven by VFD-motor systems have encountered torsional vibration problems. This vibration can induce large...

Han, Xu

2012-02-14

365

International Workshop on Time-Variable Phenomena in the Jovian System. (Abstract Only),  

National Technical Information Service (NTIS)

Many of the scientifically interesting phenomena that occur in the Jovian system are strongly time variable. Some are episodic (e.g., Io volcanism); some are periodic (wave transport in Jupiter's atmosphere); and some are exceedingly complex (magnetospher...

M. J. S. Belton, R. A. West

1988-01-01

366

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

367

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

368

Generalized treatment of optically-induced forces and potentials in optomechanically variable photonic systems.  

SciTech Connect

The authors establish a fundamental relationship between the phase and amplitude responses of an optomechanically variable photonic circuit and the forces and potentials produced by light. These results are illustrated through resonant and nonresonant multi-port systems.

Rakich, Peter T.; Wang, Zheng (Massachusetts Institute of Technology, Cambridge, MA); Popovic, Milos A. (Massachusetts Institute of Technology, Cambridge, MA)

2009-01-01

369

Interacting Compact Binaries: Modeling Mass Transfer in Eccentric Systems  

NASA Astrophysics Data System (ADS)

We discuss mass transfer in eccentric binaries containing a white dwarf and a neutron star (WD-NS binaries). We show that such binaries are produced from field binaries following a series of mass transfer episodes that allow the white dwarf to form before the neutron star. We predict the orbital properties of binaries similar to the observed WD-NS binary J1141+6545, and show that they will undergo episodic mass transfer from the white dwarf to the neutron star. Furthermore, we describe oil-on-water, a two-phase SPH formalism that we have developed in order to model mass transfer in such binaries.

Church, R. P.; Davies, M. B.; Bobrick, A.; Tout, C. A.

2012-07-01

370

The mass, energy, space and time system theory of universe -MEST  

Microsoft Academic Search

Things have their own system of mass, energy, space and time of themself. (The MEST for short thereinafter). Mass is density, energy is force, time is frequency, spac is amplitude square. In MEST of White hole, Mass-energy particle condense to center, Space-time wave radiate to Around. Solar system is a MEST of White hole. Sun is mainly mass-energy; light wave

Dayong Cao

2008-01-01

371

Assessment of variable-cycle propulsion systems for ASTOVL  

Microsoft Academic Search

The requirements imposed upon advanced short take-off and vertical landing (ASTOVL) aircraft give rise to challenging demands on their propulsion systems. One possible approach is to have a high-performance turbofan of traditional design and an additional, but separate, fan to provide a major part of the lift during the take-off and landing manoeuvres. For such a design, there are several

J. Yin; P. Pilidis; K. W. Ramsden; S. D. Probert

2000-01-01

372

An LED-based photovoltaic measurement system with variable spectrum and flash speed  

Microsoft Academic Search

Outdoor environmental variability generates the need for indoor systems for PV module characterisation. To combine the advantages of the most commonly used simulators (steady-state and pulsed) and eliminate their disadvantages, an LED-based solar simulator prototype has been developed. The system can produce light at variable flash speeds and pulse shapes or can operate as a continuous light source for long-term

M. Bliss; T. R. Betts; R. Gottschalg

2009-01-01

373

Automatically Finding the Control Variables for Complex System Behavior  

NASA Technical Reports Server (NTRS)

Testing large-scale systems is expensive in terms of both time and money. Running simulations early in the process is a proven method of finding the design faults likely to lead to critical system failures, but determining the exact cause of those errors is still time-consuming and requires access to a limited number of domain experts. It is desirable to find an automated method that explores the large number of combinations and is able to isolate likely fault points. Treatment learning is a subset of minimal contrast-set learning that, rather than classifying data into distinct categories, focuses on finding the unique factors that lead to a particular classification. That is, they find the smallest change to the data that causes the largest change in the class distribution. These treatments, when imposed, are able to identify the factors most likely to cause a mission-critical failure. The goal of this research is to comparatively assess treatment learning against state-of-the-art numerical optimization techniques. To achieve this, this paper benchmarks the TAR3 and TAR4.1 treatment learners against optimization techniques across three complex systems, including two projects from the Robust Software Engineering (RSE) group within the National Aeronautics and Space Administration (NASA) Ames Research Center. The results clearly show that treatment learning is both faster and more accurate than traditional optimization methods.

Gay, Gregory; Menzies, Tim; Davies, Misty; Gundy-Burlet, Karen

2010-01-01

374

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

375

Dynamical evolution of rotating stellar systems - I. Pre-collapse, equal-mass system  

Microsoft Academic Search

The influence of rotation on the dynamical evolution of collisional stellar systems is investigated by solving the orbit-averaged Fokker-Planck equation in (E,Jz) space. We find that large amounts of initial rotation drive the system into a phase of strong mass loss while it is moderately contracting. The core is rotating even faster than before, although angular momentum is transported outwards.

Christian Einsel; Rainer Spurzem

1999-01-01

376

Design and control of a variable-speed generator system for a WECS (wind energy conversion system)  

Microsoft Academic Search

Sandia National Laboratories has been funded by the Wind\\/Ocean Technologies Division of the DOE to design and build a 34-meter diameter VAWT research Test Bed incorporating a constant frequency, variable speed generator system (VSGS). The turbine will be utilized to evaluate aerodynamic and structural dynamic technological advances and to develop and test variable speed control algorithms. These algorithms are intended

Ralph

1987-01-01

377

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

378

Application of two-stage fuzzy PID control in variable refrigerant volume air conditioning systems  

Microsoft Academic Search

The variable refrigerant volume (VRV) air conditioning systems have been employed in small and medium sized buildings recently for its advantages of comfort, energy conservation and easy maintenance. However, the optimal control of VRV air conditioning systems is very difficult due to cross-coupling system parameters and time-variant operating conditions. In this paper, the indoor temperatures are taken as the controlled

Xu Jinqiang; Feng Zi-ping

2009-01-01

379

Nonlinear state space modeling of a variable speed wind power generation system  

Microsoft Academic Search

New problems emerging from the increased production of power from renewable resources are becoming a good challenge. To face the new challenges, accurate modeling of such systems is required. For example, to be able to apply advanced control strategies, usually a linearized state space representation of the system is needed. Taking a variable speed cage machine wind generation system as

S. H. Edjtahed; M. Karrari; W. Rosehart; O. P. Malik

2006-01-01

380

Subjective Effects of Variable Delay and Speech Clipping in Dynamically Managed Voice Systems  

Microsoft Academic Search

The purpose of this paper is to examine speech impairments likely to arise in dynamically managed voice (DMV) systems. DMV systems utilize speech activity detection to exploit speech idle time and variable bit rate coding to exploit nonstationary speech statistics. The emphasis here is on systems using speech detection. This processing introduces two impairments not commonly found in traditional communication

JOHN G. GRUBER; LEO STRAWCZYNSKI

1985-01-01

381

Variable-Assist SBW 2WS Conversion Mechatronic Control Systems  

Microsoft Academic Search

\\u000a An automotive M-F-M FPS, E-M-F-M EFPS or E-M EPS SBW 2WS conversion enhances steering performance and betters the feel of\\u000a the steering and powersaving efficiency. It does so with conversion mechatronic control mechanisms that decrease the steering\\u000a effort. An automotive FPS, EFPS or EPS SBW 2WS conversion mechatronic control system is joined to the M-F-M, E-M-F-M or E-M\\u000a booster actuator,

B. T. Fijalkowski

382

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

383

Statistical measures of complexity for quantum systems with continuous variables  

NASA Astrophysics Data System (ADS)

The Fisher-Shannon statistical measure of complexity is analyzed for a continuous manifold of quantum observables. It is shown that evaluating this measure only in the configuration or in the momentum spaces does not provide an adequate characterization of the complexity of some quantum systems. In order to obtain a more complete description of complexity two new measures, respectively based on the minimization and the integration of the usual Fisher-Shannon measure over all the parameter space, are proposed and compared. Finally, these measures are applied to the concrete case of a free particle in a box.

Manzano, D.

2012-12-01

384

Drive system for the retraction/extension of variable diameter rotor systems  

NASA Technical Reports Server (NTRS)

A drive system for a variable diameter rotor (VDR) system includes a plurality of rotor blade assemblies with inner and outer rotor blade segments. The outer blade segment being telescopically mounted to the inner blade segment. The VDR retraction/extension system includes a drive housing mounted at the root of each blade. The housing supports a spool assembly, a harmonic gear set and an electric motor. The spool assembly includes a pair of counter rotating spools each of which drive a respective cable which extends through the interior of the inboard rotor blade section and around a pulley mounted to the outboard rotor blade section. In operation, the electric motor drives the harmonic gear set which rotates the counter rotating spools. Rotation of the spools causes the cables to be wound onto or off their respective spool consequently effecting retraction/extension of the pulley and the attached outboard rotor blade section relative the inboard rotor blade section. As each blade drive system is independently driven by a separate electrical motor, each independent VDR blade assembly is independently positionable.

Gmirya, Yuriy (Inventor)

2003-01-01

385

Orbits and Masses in the young triple system TWA 5  

NASA Astrophysics Data System (ADS)

TWA5 is one of the 5 original members of the TW Hydrae association. It is composed of three components: a pair of low-mass stars, TWA 5Aa-b, and a brown dwarf companion, TWA 5B. TWA 5Aa-b had a separation of 55mas when it was discovered in 2000, while TWA 5B is located about 2arcsec away. We obtained new relative astrometric measurements of all three components with NACO at the VLT. We use these observations and data from the literature to derive an improved fit for the orbit of TWA 5Aa/Ab around each other. Furthermore, we use TWA 5B as astrometric reference to solve for the individual orbits of Aa and Ab. This allows us to estimate the mass ratio of Aa and Ab, and hence individual masses of the two components. We compare the resulting masses to masses predicted by theoretical evolutionary tracks.

Khler, Rainer; Ratzka, Thorsten; Petr-Gotzens, Monika

2013-07-01

386

Periodic variability and binary black hole systems in blazars  

E-print Network

We consider the periodic modulation of emission from jets in blazar-type sources. A differential Doppler boosting origin, associated with the helical motion of a radiating component, is analyzed for different periodic driving sources including orbital motion and jet precession in a binary black hole system (BBHS). We emphasize that for non-ballistic helical motion classical travel time effects can lead to strong shortening effects, such that the observed period may be a factor $\\gamma_b^2$ smaller than the underlying driving period, where $\\gamma_b$ denotes the bulk Lorentz factor of the jet flow. The relevance of the above noted scenarios is discussed for the BL Lac object AO 0235+16.

Frank M. Rieger

2005-06-29

387

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

388

An expert system/ion trap mass spectrometry approach for life support systems monitoring  

NASA Technical Reports Server (NTRS)

Efforts to develop sensor and control system technology to monitor air quality for life support have resulted in the development and preliminary testing of a concept based on expert systems and ion trap mass spectrometry (ITMS). An ITMS instrument provides the capability to identify and quantitate a large number of suspected contaminants at trace levels through the use of a variety of multidimensional experiments. An expert system provides specialized knowledge for control, analysis, and decision making. The system is intended for real-time, on-line, autonomous monitoring of air quality. The key characteristics of the system, performance data and analytical capabilities of the ITMS instrument, the design and operation of the expert system, and results from preliminary testing of the system for trace contaminant monitoring are described.

Palmer, Peter T.; Wong, Carla M.; Yost, Richard A.; Johnson, Jodie V.; Yates, Nathan A.; Story, Michael

1992-01-01

389

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

2013-10-30

390

Determination of Intra-Test Variability of Trace Elements in Foraminifera by Laser Ablation Inductively Coupled Plasma Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Analysis of trace elements in fossil foraminiferal tests is widely used by palaeoceanographers to reconstruct past environmental conditions in the oceans. However, there remain a number of problems associated with the interpretation of these trace element data. Firstly, there is a lack of understanding as to the controls on the uptake of trace elements into foraminiferal tests. Secondly, fossil test chemistry may be influenced by post-depositional diagenesis, and thirdly, the impact of chemical cleaning techniques, used to remove contaminant detrital and authigenic mineral phases from the test surface, on test chemistry is uncertain. In order to address these problems, information is required as to the variability of trace elements within individual foram tests. To this end, we have developed a technique for the analysis of trace elements in foraminiferal calcite by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). This technique is reproducible (<6 % for most elements), and has low detection limits. The accuracy of the technique is difficult to assess, but Mg/Ca, Sr/Ca and Li/Ca ratios for foraminiferal calcite are within the range reported elsewhere in the literature when normalised to a CaCO3 standard. Analysis of different types of calcite within a foram test shows that Sr/Ca and Li/Ca of calcite pustules surrounding the aperture of Gr. tumida are distinctly different from the chamber and keel calcite. Successive analyses of the same Orbulina universa test throughout a chemical cleaning procedure show that the Mg/Ca ratio of the test falls significantly after removal of ferromanganese oxide phases, but is unchanged after oxidative cleaning. Rastering of relatively flat parts of G. sacculifer has enabled us to investigate changes in chemistry through the test wall. High Li/Ca on the outermost part of the test can be attributed to contaminant phases, but Li/Ca is relatively constant at >5 ?m depth. The depth of this `contaminant' layer is significantly shallower if the foram is glassy, rather than opaque.

Hathorne, E. C.; James, R. H.; Alard, O.; Rogers, N. W.

2002-12-01

391

A completely automated CAD system for mass detection in a large mammographic database  

Microsoft Academic Search

Mass localization plays a crucial role in computer-aided detection (CAD) systems for the classification of suspicious regions in mammograms. In this article we present a completely automated classification system for the detection of masses in digitized mammographic images. The tool system we discuss consists in three processing levels: (a) Image segmentation for the localization of regions of interest (ROIs). This

R. Bellotti; F. De Carlo; S. Tangaro; G. Gargano; G. Maggipinto; M. Castellano; R. Massafra; D. Cascio; F. Fauci; R. Magro; G. Raso; A. Lauria; G. Forni; S. Bagnasco; P. Cerello; E. Zanon; S. C. Cheran; E. Lopez Torres; U. Bottigli; G. L. Masala; P. Oliva; A. Retico; M. E. Fantacci; R. Cataldo; I. De Mitri; G. De Nunzio

2006-01-01

392

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

393

The Coordinated Control of a Central Air Conditioning System Based on Variable Chilled Water Temperature and Variable Chilled Water Flow  

E-print Network

of coordinative optimization control for variable chilled water temperature and variable chilled water flow to obtain better power savings is put forward. According to typical meteorological year data, hourly air conditioning load of whole year for every typical...

Liu, J.; Mai, Y.; Liu, X.

2006-01-01

394

Accumulation Rate Variability and Winter Mass Balance Estimates using High Frequency Ground-Penetrating Radar and Snow Pit Stratigraphy on the Juneau Icefield, Alaska  

NASA Astrophysics Data System (ADS)

In July 2012, 200 km of 400 MHz ground-penetrating radar (GPR) profiles were collected across the Juneau Icefield, Alaska. The goal was to determine if spatial accumulation rate variability and winter mass balance estimates could be improved by linking stratigraphic features between yearly-excavated snow pits through GPR. Profiles were collected along the centerline and cross sections of the main branch, northwest, and Southwest branch of the Taku Glacier as well as the Mathes, Llewellyn, and Demorest Glaciers. Over 650 km^2 of area and 1000 m of elevation range were covered during this pilot project linking sixteen snow pits with GPR data across the icefield. The field work was conducted as part of the Juneau Icefield Research Program (JIRP) with hopes of continuing this method in future years if first year results show promise. As an annually operated field research and education program, JIRP creates a unique opportunity to provide significant future contributions to Alaska mass balance records if the program is continued. Signal penetration reached ? 25 m with maximum depths reached at higher elevations of the icefield. Conversely, minimal penetration occurred in wetter regions at lower elevations, likely caused by volume scattering from free water within the firn and ice. Ice lenses and the annual layer located in mass balance snow pits correlated well with continuous stratigraphy imaged in GPR profiles suggesting that the lenses are relatively uninterrupted across the icefield and that GPR may be an appropriate tool for extrapolating point mass balance pit depths in this part of Alaska. The Northwest and Southwest Branches of the Taku Glacier show a strong stratigraphic thinning gradient, west to east; the main trunk of the Taku Glacier which originates from the Mathes-Llewellyn ice divide showed a similar thinning from the divide to the ELA. The thinning displayed by all three glacier systems matches a typical gradient from accumulation zone to ELA. However, it is also likely that a local influx of accumulation at the higher elevations of the Southwest and Northwest Branches result from their close proximity of the ocean. Beyond mass balance estimates, radar profiles also revealed ablation horizons underlying the annual layer near the ELA. Monitoring the location of this ablation horizon relative to the annual balance reflector may be helpful in quantifying changes in the ELA at the end of each previous melt season. Perched water tables were also imaged in several locations which may be suitable for future hydrological studies focused on delineation of sub-glacial drainage systems and their impact on local glacier dynamics. This is a particularly interesting finding considering the unprecedented recent jokulhlaup of the Mendenhall Glacier and re-routing of the primary water drainage at the Llewellyn Glacier terminus in 2011.

Braddock, S. S.; Boucher, A. L.; Sandler, H. C.; McNeil, C.; Campbell, S. W.; Kreutz, K. J.

2012-12-01

395

Portable, Automated, Inexpensive Mass and Balance Calibration System.  

National Technical Information Service (NTIS)

Reliable mass measurements are essential for a nuclear production facility or process control laboratory. DOE Order 5630.2 requires that traceable standards be used to calibrate and monitor equipment used for nuclear material measurements. To ensure the r...

S. L. Maxwell, J. P. Clark

1987-01-01

396

Electronic drive and acquisition system for mass spectrometry  

NASA Technical Reports Server (NTRS)

The present invention discloses a mixed signal RF drive electronics board that offers small, low power, reliable, and customizable method for driving and generating mass spectra from a mass spectrometer, and for control of other functions such as electron ionizer, ion focusing, single-ion detection, multi-channel data accumulation and, if desired, front-end interfaces such as pumps, valves, heaters, and columns.

Schaefer, Rembrandt Thomas (Inventor); Mojarradi, Mohammad (Inventor); Chutjian, Ara (Inventor); Darrach, Murray R. (Inventor); MacAskill, John (Inventor); Tran, Tuan (Inventor); Burke, Gary R. (Inventor); Madzunkov, Stojan M. (Inventor); Blaes, Brent R. (Inventor); Thomas, John L. (Inventor)

2010-01-01

397

Simulation of Variable Speed Wind Generation System Using Boost Converter of Permanent Magnet Synchronous Generator  

NASA Astrophysics Data System (ADS)

This paper proposes variable-speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of wind turbine. The hybrid of three control modes extends the variable-speed range. The proposed system simplifies the maintenance and improves the reliability and reduces the cost in compare with the variable-speed wind generation system using PWM converter. This paper describes the control strategy and modeling for simulation using Matlab Simulink of the proposed system. Also this paper describes the control strategy and modeling of variable-speed wind generation system using PWM converter. The steady state and transient responses for wind velocity changes are simulated using the Matlab Simulink. This paper verifies the fundamental performance of the system using boost converter by discussing the simulation results of the both systems.

Ohyama, Kazuhiro; Sakamoto, Tsuyoshi; Arinaga, Shinji; Yamashita, Yukio

398

IDENTIFICATION OF A WIDE, LOW-MASS MULTIPLE SYSTEM CONTAINING THE BROWN DWARF 2MASS J0850359+105716  

SciTech Connect

We report our discovery of NLTT 20346 as an M5+M6 companion system to the tight binary (or triple) L dwarf 2MASS J0850359+105716. This nearby ({approx}31 pc), widely separated ({approx}7700 AU) quadruple system was identified through a cross-match of proper motion catalogs. Follow-up imaging and spectroscopy of NLTT 20346 revealed it to be a magnetically active M5+M6 binary with components separated by {approx}2'' (50-80 AU). Optical spectroscopy of the components shows only moderate H{alpha} emission corresponding to a statistical age of {approx}5-7 Gyr for both M dwarfs. However, NLTT 20346 is associated with the XMM-Newton source J085018.9+105644, and based on X-ray activity the age of NLTT 20346 is between 250 and 450 Myr. Strong Li absorption in the optical spectrum of 2MASS J0850+1057 indicates an upper age limit of 0.8-1.5 Gyr, favoring the younger age for the primary. Using evolutionary models in combination with an adopted system age of 0.25-1.5 Gyr indicates a total mass for 2MASS J0850+1057 of 0.07 {+-} 0.02 M{sub sun}, if it is a binary. NLTT 20346/2MASS J0850+1057 joins a growing list of hierarchical systems containing brown dwarf binaries and is among the lowest binding energy associations found in the field. Formation simulations via gravitational fragmentation of massive extended disks have successfully produced a specific analog to this system.

Faherty, Jacqueline K. [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10034 (United States); Burgasser, Adam J. [Center of Astrophysics and Space Sciences, Department of Physics, University of California, San Diego, CA 92093 (United States); Bochanski, John J. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Looper, Dagny L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Avenue Boston, MA 02215 (United States); Van der Bliek, Nicole S., E-mail: jfaherty@amnh.org [CTIO/National Optical Astronomy Observatory, Casilla 603, La Serena (Chile)

2011-03-15

399

PREPROCESSING, VARIABLE SELECTION AND CLASSIFICATION RULES IN THE APPLICATION OF SIMCA PATTERN RECOGNITION TO MASS SPECTRAL DATA  

EPA Science Inventory

In a recent report a strategy was proposed for the classification and identification of toxic organic compounds observed in ambient air from mass spectra using computational pattern recognition based on SlMCA principal components modeling of the autocorrelation transformed mass s...

400

Design and fabrication of a basic mass analyzer and vacuum system  

NASA Technical Reports Server (NTRS)

A two-inch hyperbolic rod quadrupole mass analyzer with a mass range of 400 to 200 amu and a sensitivity exceeding 100 packs per billion has been developed and tested. This analyzer is the basic hardware portion of a microprocessor-controlled quadrupole mass spectrometer for a Gas Analysis and Detection System (GADS). The development and testing of the hyperbolic-rod quadrupole mass spectrometer and associated hardware are described in detail.

Judson, C. M.; Josias, C.; Lawrence, J. L., Jr.

1977-01-01

401

The CIDA Variability Survey of Orion OB1. I. The Low-Mass Population of Ori OB1a and 1b  

Microsoft Academic Search

We present results of a large-scale, multiepoch optical survey of the Orion OB1 association, carried out with the QUEST camera at the Venezuela National Astronomical Observatory. We identify for the first time the widely spread low-mass, young population in the Ori OB1a and OB1b subassociations. Candidate members were picked up by their variability in the V band and position in

Cesar Briceo; Nuria Calvet; J. Hernndez; A. K. Vivas; Lee Hartmann; J. J. Downes; Perry Berlind

2005-01-01

402

Solutions with separated variables and breather structures in the (1+1)-dimensional nonlinear systems  

NASA Astrophysics Data System (ADS)

In this Letter, the multilinear variable separation approach is extended to (1+1)-dimensional nonlinear systems, and the independent variables of these systems are totally separated. A common formula with some arbitrary functions is derived to describe suitable physical quantities for some (1+1)-dimensional models such as the negative KdV hierarchy, the long-wave short-wave resonant interaction equation, the Ito system, the shallow water wave equations and the coupled integrable dispersionless equations. Based on the formula and by selecting appropriate functions, rich breather structures, such as soliton-type, peakon-type, compacton-type, foldon-type breathers, can be investigated.

Zhang, Jie-Fang; Dai, Chao-Qing; Xu, Chang-Zhi; Meng, Jian-Ping; Lai, Xian-Jing

2006-04-01

403

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...

404

Accumulation-based concurrent fault detection for linear digital state variable systems  

Microsoft Academic Search

An algorithmic fault detection scheme for linear digital state variable systems is proposed. The proposed scheme eliminates the necessity of observing the internal states of the system for concurrent fault detection by utilizing an accumulation-based approach. Observation merely of the inputs and the outputs results in significantly reduced area overhead and no performance penalty. Experimental re- sults verify that 100%

Ismet Bayraktaroglu; Alex Orailoglu

2000-01-01

405

A new cardiac nervous system model for heart rate variability analysis  

Microsoft Academic Search

Heart rate variability (HRV) provides a noninvasive means of quantifying cardiac autonomic activity. Imbalances in autonomic activity between the sympathetic and parasympathetic systems accompany a number of cardiac disorders. This paper provides new results in mathematically modeling the cardiac nervous system responsible for fluctuations in heart rate. These results clearly demonstrate the differing varieties of heart rate fluctuations over a

M. Brennan; M. Palaniswami; P. W. Kamen

1998-01-01

406

Design of a Variable Speed Compressor Drive System for Air-Conditioner without Electrolytic Capacitor  

Microsoft Academic Search

This paper presents an electrolytic capacitor-less variable speed drive system for the compressor of an air-conditioner to enhance cost and size competitiveness and reliability. The electrolytic capacitor in the DC link of the inverter is replaced by a small film capacitor, whose capacitance is around a couple thousandth of the conventional drive system. Due to the small capacitance, not only

Hyunjae Yoo; Seung-Ki Sul; Hoyong Jang; Youngho Hong

2007-01-01

407

Modelling and Reconstruction of the North Atlantic Climate System Variability (MONALISA III)  

E-print Network

-ocean system shows low-frequency regime behavior (e.g., the Atlantic Multidecadal Oscillation; AMO; Dijkstra et12 P 1.1 Modelling and Reconstruction of the North Atlantic Climate System Variability (MONALISA to changes in external forcing functions in the North Atlantic during key periods of the past 1000 years

Richner, Heinz

408

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

409

Robustness of Social-Ecological Systems to Spatial and Temporal Variability  

Microsoft Academic Search

Some social-ecological systems (SESs) have persisted for hundreds of years, remaining in particular configurations that have withstood a variety of natural and social disturbances. Many of these long-lived SESs have adapted their institutions to the particular pattern of variability they have experienced over time as well as to the broader economic, political, and social system in which they are located.

Marco A. Janssen; John M. Anderies; Elinor Ostrom

2007-01-01

410

Zernike representation and Strehl ratio of optical systems with variable numerical aperture  

Microsoft Academic Search

We consider optical systems with variable numerical aperture (NA) on the level of the Zernike coefficients of the correspondingly scalable pupil function. We thus present formulas for the Zernike coefficients and their first two derivatives as a function of the scaling factor ? ? 1, and we apply this to the Strehl ratio and its derivatives of NA-reduced optical systems.

A. J. E. M. Janssen; S. van Haver; P. Dirksen; J. J. M. Braat

2008-01-01

411

Sixth Goddard Conference on Mass Storage Systems and Technologies Held in Cooperation with the Fifteenth 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 Sixth Goddard Conference on Mass Storage Systems and Technologies which is being held in cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems at the University of Maryland-University College Inn and Conference Center March 23-26, 1998. 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, tape optimization, new technology, performance, standards, site reports, vendor solutions. Tutorials will be available on shared file systems, file system backups, data mining, and the dynamics of obsolescence.

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

1998-01-01

412

Low Mass Density Wide Field Far-IR/Submillimeter Telescope Systems  

E-print Network

Fundamentally new technology is described for constructing low areal mass density (1kg/m^2), high precision (< 10micron RMS) reflectors scalable to large apertures (10 to 20 meters) for use as the primary element of a telescope system. A large reduction in mass is achieved by minimizing the mass of the reflective surface using a high reflectivity metallic membrane. A wide field diffraction limited telescope system can be constructed using the primary reflector in conjunction with secondary and tertiary optics.

Mark Dragovan

2000-01-13

413

Effect of mass loss on the dynamical evolution of a stellar system: Analytic approximations  

Microsoft Academic Search

If half or more of the mass of a virialized system is lost in less than one dynamical crossing time, the system dissocites. If the mass loss occurs in a collapsing protosystem with uniform density, no angular momentum, and relatively little radiation of energy, the minimum fractional mass loss required for dissociation is reduced to ..delta..M\\/M=R\\/sub c\\/\\/(2R). Here R\\/sub c\\/

J. G. Hills

1980-01-01

414

Seasonal variability of water mass distribution in the southeastern Beaufort Sea determined by total alkalinity and d18  

E-print Network

masses, including the Mackenzie River, sea ice melt (SIM), winter polar mixed layer (PML), upper) over the study period. The influence of the Mackenzie River ( fCO2-SW > 500 matm) was relatively small

Paris-Sud XI, Université de

415

Development of a variable-temperature ion mobility/ time-of-flight mass spectrometer for separation of electronic isomers  

E-print Network

The construction of a liquid nitrogen-cooled ion mobility spectrometer coupled with time-of-flight mass spectrometry was implemented to demonstrate the ability to discriminate between electronic isomers. Ion mobility allows for the separation...

Verbeck, Guido Fridolin

2005-08-29

416

Model-Driven Development of Decision Support Systems: Tackling the Variability Problem  

NASA Astrophysics Data System (ADS)

In this chapter, we present software variability management using conceptual models for diagnostic decision support information systems (DSS) development. We use a software product line (SPL) approach. In the construction of the SPL, two orthogonal variabilities are used to capture domain (i.e., diagnosis) and application domain (i.e., medical diagnosis) particularities. In this context, we describe how variability is managed by using our BOM (baseline-oriented modeling) approach. BOM is a framework that automatically generates applications as PRISMA software architectural models using model transformations and SPL techniques. We use model-driven architecture (MDA) to build domain models (i.e., computational-independent models, CIMs), which are automatically transformed into platform-independent models, PIMs, and then compiled to a executable application (i.e., platform-specific model, PSM). In order to illustrate BOM, we focus on a type of information system, the decision support system, specifically in the diagnostic domain.

Cabello, Mara Eugenia; Ramos, Isidro

417

Optimal control of singularly perturbed nonlinear systems with state-variable inequality constraints  

NASA Technical Reports Server (NTRS)

The established necessary conditions for optimality in nonlinear control problems that involve state-variable inequality constraints are applied to a class of singularly perturbed systems. The distinguishing feature of this class of two-time-scale systems is a transformation of the state-variable inequality constraint, present in the full order problem, to a constraint involving states and controls in the reduced problem. It is shown that, when a state constraint is active in the reduced problem, the boundary layer problem can be of finite time in the stretched time variable. Thus, the usual requirement for asymptotic stability of the boundary layer system is not applicable, and cannot be used to construct approximate boundary layer solutions. Several alternative solution methods are explored and illustrated with simple examples.

Calise, A. J.; Corban, J. E.

1990-01-01

418

Power-law mass distribution of aggregation systems with injection  

Microsoft Academic Search

We introduce a new family of aggregation models with constant interjection. In our models, the asymptotic distribution of particle mass, s, always follows a power law, P(>=s)~s-alpha, where (1\\/3<=alpha<= 1) \\/ 2 . It is clarified that this power law is realized by a balance of two effects, injection and aggregation.

Hideki Takayasu; Ikuko Nishikawa; Hal Tasaki

1988-01-01

419

Plant tests of an on-line multiple-pipe pulverised coal mass flow measuring system  

Microsoft Academic Search

The CSIRO Division of Minerals has developed and successfully plant-tested a commercial prototype pulverised fuel (PF) mass flow measurement system on all four boiler feed lines from a single pulverising mill at Bayswater power station, in the Hunter Valley, NSW, Australia. The CSIRO PF mass flow measurement system utilises measurements of the attenuation and velocity of pulsed beams of 60

M. J Millen; B. D Sowerby; P. J Coghill; J. R Tickner; R Kingsley; C Grima

2000-01-01

420

Time resolved mass flow measurements for a fast gas delivery system  

Microsoft Academic Search

A technique is demonstrated whereby the delivered mass and flow rate versus time of a short rise-time gas delivery system may be accurately determined. The gas mass M that flows past a point in a gas delivery system by an arbitrary time t=tp may be accurately measured if that point is sealed off with a fast closing valve within a

E. L. Ruden; J. H. Degnan; T. W. Hussey; M. C. Scott; J. D. Graham; S. K. Coffey

1993-01-01