scholarly journals Long-term stability of the dead-zone in proto-planetary disks

2010 ◽  
Vol 6 (S276) ◽  
pp. 418-419
Author(s):  
Mario Flock ◽  
Neal Turner ◽  
Natalia Dzyurkevich ◽  
Hubert Klahr
Keyword(s):  
Dead Zone ◽  
Cosmic Ray ◽  
X Ray ◽  
Long Term Stability ◽  
Mhd Simulations ◽  
Magnetic Resistivity ◽  
Ideal Mhd ◽  
Self Consistent ◽  
Ionization Fraction

AbstractWe present 3D global non-ideal MHD simulations with a self consistent dynamic evolution of ionization fraction of the gas as result of reduced chemical network. We include X-ray ionization from the star as well as cosmic ray ionization. Based on local gas density and temperature in our chemical network, we determine the magnetic resistivity, which is fed back in MHD simulations. Parameters for dust size and abundance are chosen to have accreting layers and a laminar “dead” mid-plane.

scholarly journals 3D global simulations of proto-planetary disk with dynamically evolving outer edge of dead zone

2010 ◽  
Vol 6 (S276) ◽  
pp. 407-408
Author(s):  
Natalia Dzyurkevich ◽  
Neal J. Turner ◽  
Willy Kley ◽  
Hubert Klahr ◽  
Thomas Henning
Keyword(s):  
Turbulent Viscosity ◽  
Dead Zone ◽  
Cosmic Ray ◽  
Outer Edge ◽  
Smooth Transition ◽  
Dust Grains ◽  
X Ray ◽  
Hard Edge ◽  
Mhd Simulations ◽  
Pressure Bump

Abstract3D global MHD simulations of magneto-driven turbulence are performed for the disk of 100 AU with reduced amount of 10μm fluffy dust grains. We use X-ray and cosmic ray ionization, as well as simplified treatment of recombination on dust grains. The ionization of gas and charging of dust grains are dynamically evolving during the simulation, making the zone of high magnetic dissipation (’dead’ zone) variable. In our simulations, the jump in MRI-driven turbulent viscosity inside and outside of dead zone is insignificant. We find no hard edge, but rather a smooth transition between active and dead zone. Subsequently, there is no visible pressure bump at outer edge of the dead zone.

scholarly journals A survey of short-term and long-term stability of tube parameters in a mammography unit

2014 ◽  
Vol 29 (4) ◽  
pp. 321-325
Author(s):  
Jovica Praskalo ◽  
Jasna Davidovic ◽  
Biljana Kocic ◽  
Monika Zivkovic ◽  
Svetlana Pejovic
Keyword(s):  
Screening Program ◽  
Short Term ◽  
X Ray ◽  
Term Stability ◽  
Long Term Stability ◽  
Mammography Screening Program ◽  
The Republic ◽  
Set Up ◽  
The Given

In order to set up a successful mammography screening program in the Republic of Srpska, a Siemens Mammomat 1000 X-ray machine was selected for analysis as the said mammography system is widely used in clinical practice. The variations in tube parameters (specific air kerma, high-voltage accuracy and reproducibility, linearity between exposure and dose exposure time) were monitored over a five-year period, from 2008 to 2012. In addition, due to observed daily fluctuations for chosen parameters, a series of measurements were performed three times a day within a single-month period (mainly October 2012). The goal of such an experimental set up is to assess short-term and long-term stability of tube parameters in the given mammography unit and to make a comparison between them. The present paper shows how an early detection of significant parameter fluctuations can help eliminate irregularities and optimize the performance of mammography systems.

scholarly journals Physics of Relativistic Jets on Sub-Milliarcsecond Scales

1984 ◽  
Vol 110 ◽  
pp. 207-214
Author(s):  
Martin J. Rees
Keyword(s):  
Energy Production ◽  
Galactic Nuclei ◽  
Primary Energy ◽  
Relativistic Jets ◽  
Short Term ◽  
X Ray ◽  
Long Term Stability ◽  
Extended Sources ◽  
Vlbi Data

The observed superluminal components have (deprojected) lengths of ~ 1020 cm, and imply relativistic bulk motions on these scales. There are, however, persuasive reasons for attributing the primary energy production to scales 1014–1015 cm. Moreover, the initial bifurcation and collimation must also be imposed on these small scales if the long-term stability of the jet axis in extended sources is due to the gyroscopic effect of a spinning black hole (Rees 1978). The issues I shall address in this talk are: how the jet gets from ~ 1015cm to ~ 1019 cm; and what VLBI data can tell us about the properties of galactic nuclei on scales below ~ 1019 cm — scales where optical and X-ray studies provide some evidence, but where there is no short-term hope of achieving spatial resolution.

Synthesis of Trilaminar Core–Shell Au/α-Fe2O3@SnO2Nanocomposites and their Application for Nonenzymatic Dopamine Electrochemical Sensing

NANO ◽  
2019 ◽  
Vol 14 (11) ◽  
pp. 1950138 ◽  
Author(s):  
Sai Zhang ◽  
Shijun Yue ◽  
Jiajia Li ◽  
Jianbin Zheng ◽  
Guojie Gao
Keyword(s):  
Electron Microscopy ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Synthesis Process ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Term Stability ◽  
Transmission Electron

Au nanoparticles anchored on core–shell [Formula: see text]-Fe2O3@SnO2 nanospindles were successfully constructed through hydrothermal synthesis process and used for fabricating a novel nonenzymatic dopamine (DA) sensor. The structure and morphology of the Au/[Formula: see text]-Fe2O3@SnO2 trilaminar nanohybrid film were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical properties of the sensor were investigated by cyclic voltammetry and amperometry. The experimental results suggest that the composites have excellent catalytic property toward DA with a wide linear range from 0.5[Formula: see text][Formula: see text]M to 0.47[Formula: see text]mM, a low detection limit of 0.17[Formula: see text][Formula: see text]M (S/[Formula: see text]) and high sensitivity of 397.1[Formula: see text][Formula: see text]A[Formula: see text]mM[Formula: see text][Formula: see text]cm[Formula: see text]. In addition, the sensor exhibits long-term stability, good reproducibility and anti-interference.

Long‐term stability of invisible X‐ray fluorescence identification tags

2019 ◽  
Vol 49 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Barbora Benetková ◽  
Jan Krejčí ◽  
Klára Drábková ◽  
Michal Ďurovič ◽  
Michal Veselý ◽  
...  
Keyword(s):  
X Ray ◽  
Term Stability ◽  
Long Term Stability ◽  
Identification Tags

Carbon Dioxide Reforming of Methane over Ni/Mo/La2O3-SBA-15 Сatalyst

2012 ◽  
Vol 455-456 ◽  
pp. 960-965
Author(s):  
Jian Huang ◽  
T. Huang ◽  
A. Rongzhang ◽  
Wei Huang ◽  
Ren Xiong Ma
Keyword(s):  
Carbon Dioxide ◽  
Strong Interaction ◽  
Carbon Deposition ◽  
Catalytic Performance ◽  
Stability Test ◽  
X Ray Diffraction ◽  
Carbon Dioxide Reforming ◽  
X Ray ◽  
Long Term Stability

Carbon dioxide reforming of methane over Ni/Mo/ La2O3-SBA-15 was studied. The catalyst was characterized by N2 adsorption, X-ray diffraction, H2-TPR,CO2-TPD and TG-GTA analysis. The results indicated that the introduction of an appropriate amount of La2O3 exhibited a higher activity and stability. In the long term stability test, La2O3 impregnated Ni/Mo-SBA-15 gave the highest conversion and stable activity at 800°C for 250 h. The effect of La was suggested to be due to its lower tendency to carbon deposition. Characterization results showed a strong interaction between La and Mo or Ni which facilitated the improvement of catalytic performance.

Material Aspects of A-Sin:H Based 2D Direct X-Ray Sensor Array

1998 ◽  
Vol 507 ◽  
Author(s):  
I. Popov ◽  
G. Van Doorselaer ◽  
A. Van Calster ◽  
H. De Smet ◽  
E. Boesman ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Sensor Array ◽  
X Ray ◽  
Term Stability ◽  
Long Term Stability

ABSTRACTThe possibility of creating an 2D X-ray sensor array on the base of a-SiN:H thin films without switching elements and an X-ray conversion layer is presented in this report. The behavior of a-SiN:H Thin-Film Diode under X-ray irradiation, its limitations, and ways of increasing long-term stability and sensitivity of the sensor are discussed.

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