scholarly journals Modelling the Ejection of Meteoroids from Comets

1996 ◽  
Vol 150 ◽  
pp. 137-140
Author(s):  
J. Jones ◽  
P. Brown
Keyword(s):  
Active Area ◽  
Adiabatic Expansion ◽  
Process Change ◽  
Meteor Stream ◽  
Spherical Cap ◽  
Ejection Process

AbstractWe have reworked Whipple's (1951) theory of the ejection of meteoroids from comets to include the effects of cooling by the sublimation of the cometary ice and the adiabatic expansion of the escaping gases. We consider only those particles moving significantly slower than the gas speed and find that the inclusion of these effects does not yield results much different from Whipple's theory. We have extended the theory to include the case of an active area in the form of a spherical cap and have shown how the characteristics of the ejection process change when the cap is in the form of a pit or a depression. We present a empirical formulae which should be useful to modellers of meteor stream evolution.

scholarly journals Dynamic and Probabilistic Relation between Meteoroids and their Parent Bodies

1996 ◽  
Vol 150 ◽  
pp. 133-136
Author(s):  
Lars G. Adolfsson ◽  
Bo Å. S. Gustafson
Keyword(s):  
Solar Wind ◽  
Radiation Pressure ◽  
Parent Body ◽  
The Sun ◽  
Ejection Velocity ◽  
Meteor Stream ◽  
Level Of Activity ◽  
Ejection Process ◽  
Probabilistic Relation ◽  
Cometary Activity

AbstractWe estimate the probability that specific meteoroids were produced by a specific parent body and obtain the ejection velocity and several other conditions of the ejection as a by-product. The duration of cometary activity leading to a meteor stream, or the epoch of a collision can be estimated from the ejection times of meteoroids in the same stream. The level of activity of a comet or probability of asteroid collisions can be estimated from the part of the orbit where ejection took place. We show that Phaethon ejected Geminid meteoroids over at least 3000 years lasting to as recently as ≈ AD 1600. Ejections are predominantly in the direction of the sun, i.e., from Phaethon's day side, and give insights into the ejection process which is suggestive of cometary activity. Our calculations account for the uncertainty in the observational data and include the effects of planetary perturbations, radiation pressure, Poynting-Robertson light drag and solar wind corpuscular drag.

Reduction of Triangular Defects on 100mm 4° off-axis 4H-SiC using a Chloride Based CVD process

2012 ◽  
Vol 1433 ◽  
Author(s):  
Hrishikesh Das ◽  
Swapna Sunkari ◽  
Timothy Oldham ◽  
Josh Rodgers ◽  
Janna Casady
Keyword(s):  
Surface Roughness ◽  
Core Structure ◽  
Active Area ◽  
Process Change ◽  
Homoepitaxial Layers

ABSTRACTHomoepitaxial layers were grown with very low surface roughness on 4", 4˚ off-axis substrates, but a new kind of large obtuse angled triangular defect that spanned 1000-2000 μm was observed. Process changes resulted in reduction of the size and concentration of these triangular defects from 3.5cm-2 to 0.13cm-2. Both large and small triangular defects were found to have a similar core structure. No degradation in the epitaxial morphology or quality was seen due to the process change. JBS diodes fabricated on wafers with large triangular defects had much higher leakage when the triangular defects were present in the active area of the diodes.

A Fully Differential Variable Gain Amplifier for Portable Impedance Sensing Applications

2019 ◽  
Vol 7 ◽  
Author(s):  
Jorge Pérez Bailón ◽  
Jaime Ramírez-Angulo ◽  
Belén Calvo ◽  
Nicolás Medrano
Keyword(s):  
Power Consumption ◽  
Active Area ◽  
Variable Gain Amplifier ◽  
Cmos Process ◽  
Current Steering ◽  
Impedance Sensing ◽  
Variable Gain ◽  
Fully Differential ◽  
Sensing Applications ◽  
Constant Bandwidth

This paper presents a Variable Gain Amplifier (VGA) designed in a 0.18 μm CMOS process to operate in an impedance sensing interface. Based on a transconductance-transimpedance (TC-TI) approach with intermediate analog-controlled current steering, it exhibits a gain ranging from 5 dB to 38 dB with a constant bandwidth around 318 kHz, a power consumption of 15.5 μW at a 1.8 V supply and an active area of 0.021 mm2.

Design and development of all printable perovskite solar modules with 198 cm2 active area

2018 ◽  
Author(s):  
Trystan Watson ◽  
Francesca De Rossi ◽  
Jenny Baker ◽  
David Beynon ◽  
Katherine Hooper ◽  
...  
Keyword(s):  
Active Area ◽  
Design And Development

Micro-Raman Spectroscopy Evaluation of the Local Mechanical Stress in Shallow Trench Isolation CMOS Structures: Correlation with Defect Generation and Diode Leakage

1998 ◽  
Author(s):  
I. De Wolf ◽  
G. Groeseneken ◽  
H.E. Maes ◽  
M. Bolt ◽  
K. Barla ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Mechanical Stress ◽  
Defect Formation ◽  
Active Area ◽  
Wet Oxidation ◽  
Leakage Currents ◽  
Shallow Trench Isolation ◽  
Micro Raman Spectroscopy ◽  
Silicon Devices ◽  
Trench Isolation

Abstract It is shown, using micro-Raman spectroscopy, that Shallow Trench Isolation introduces high stresses in the active area of silicon devices when wet oxidation steps are used. These stresses result in defect formation in the active area, leading to high diode leakage currents. The stress levels are highest near the outer edges of line structures and at square structures. They also increase with decreasing active area dimensions.

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