scholarly journals X-ray emission processes in extragalactic jets, lobes and hot spots

2003 ◽  
Vol 47 (6-7) ◽  
pp. 417-421 ◽  
Author(s):  
Andrew S. Wilson
Keyword(s):  
X Ray ◽  
Author(s):  
Xia ◽  
Hu ◽  
Shao ◽  
Xu ◽  
Zhou ◽  
...  

To verify the feasibility of portable X-ray fluorescence (PXRF) for rapidly analyzing, assessing and improving soil heavy metals mapping, 351 samples were collected from Fuyang District, Hangzhou City, in eastern China. Ordinary kriging (OK) and co-ordinary kriging (COK) combined with PXRF measurements were used to explore spatial patterns of heavy metals content in the soil. The Getis-Ord index was calculated to discern hot spots of heavy metals. Finally, multi-variable indicator kriging was conducted to obtain a map of multi-heavy metals pollution. The results indicated Cd is the primary pollution element in Fuyang, followed by As and Pb. Application of PXRF measurements as covariates in COK improved model accuracy, especially for Pb and Cd. Heavy metals pollution hot spots were mainly detected in northern Fuyang and plains along the Fuchun River in southern Fuyang because of mining, industrial and traffic activities, and irrigation with polluted water. Area with high risk of multi-heavy metals pollution mainly distributed in plain along the Fuchun River and the eastern Fuyang. These findings certified the feasibility of using PXRF as an efficient and reliable method for soil heavy metals pollution assessment and mapping, which could contribute to reduce the cost of surveys and pollution remediation.


2018 ◽  
Vol 27 (10) ◽  
pp. 1844011 ◽  
Author(s):  
José M. Martí ◽  
Manel Perucho ◽  
José L. Gómez ◽  
Antonio Fuentes

Recollimation shocks (RS) appear associated with relativistic flows propagating through pressure mismatched atmospheres. Astrophysical scenarios invoking the presence of such shocks include jets from AGNs and X-ray binaries and GRBs. We shall start reviewing the theoretical background behind the structure of RS in overpressured jets. Next, basing on numerical simulations, we will focus on the properties of RS in relativistic steady jets threaded by helical magnetic fields depending on the dominant type of energy. Synthetic radio maps from the simulation of the synchrotron emission for a selection of models in the context of parsec-scale extragalactic jets will also be discussed.


2021 ◽  
Vol 1020 ◽  
pp. 8-12
Author(s):  
Wu Hu ◽  
Ke Zhu ◽  
Meng Wang ◽  
Wei Dong Huang ◽  
Jian Min Zeng

Linear segregation of high strength aluminum alloy ZL205A castings were studied by X-ray Nondestructive testing, scanning electron microscope and energy dispersive spectrometer. It is found that the linear segregation occurs at the large wall thickness of the casting and/or at the place where the wall thickness is in transition. Segregation element is mainly Cu, which exists as compound θ (Al2Cu) phase. The formation of linear segregation is related to the flow of Cu-rich melt in the late solidification period, while the occurrence of thermal cracks promotes the formation of linear segregation. The formation of linear segregation of the casting can be effectively prevented by eliminating hot spots of the casting, refining crystal grains and increasing solidification speed of the casting.


1989 ◽  
Author(s):  
A. Krejc̆í ◽  
E. Kruouský ◽  
O. Renner
Keyword(s):  

2019 ◽  
Vol 883 (1) ◽  
pp. L2 ◽  
Author(s):  
Eileen T. Meyer ◽  
Adurshsiva R. Iyer ◽  
Karthik Reddy ◽  
Markos Georganopoulos ◽  
Peter Breiding ◽  
...  
Keyword(s):  
X Ray ◽  

2004 ◽  
Vol 612 (2) ◽  
pp. 729-748 ◽  
Author(s):  
M. J. Hardcastle ◽  
D. E. Harris ◽  
D. M. Worrall ◽  
M. Birkinshaw
Keyword(s):  

1995 ◽  
Vol 449 ◽  
pp. 86 ◽  
Author(s):  
Amir Levinson ◽  
Roger Blandford
Keyword(s):  
X Ray ◽  

2000 ◽  
Vol 530 (2) ◽  
pp. L81-L84 ◽  
Author(s):  
D. E. Harris ◽  
P. E. J. Nulsen ◽  
T. J. Ponman ◽  
M. Bautz ◽  
R. A. Cameron ◽  
...  
Keyword(s):  

1960 ◽  
Vol 10 ◽  
pp. 706-708 ◽  
Author(s):  
Herbert Friedman

The X-ray spectrum of a quiet Sun can be approximated by a 500,000° K Planckian distribution. In the absence of coronal excitation, as evidenced by the intensity of the Fe xiv green line, the X-ray spectrum has a short wave-length limit near 20 A. Coronal activity is accompanied by weak emissions down to wave-lengths as short as 6 A, which appear to be associated with coronal hot spots at temperatures of 2 x 106° K or higher.


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