Quantitative surface damage studies by H.R.E.M.

1989 ◽  
Vol 47 ◽  
pp. 632-633
Author(s):  
S. R. Singh ◽  
H. J. Fan ◽  
L. D. Marks
Keyword(s):  
Solar Wind ◽  
Quantitative Analysis ◽  
Surface Science ◽  
Surface Damage ◽  
Space Environment ◽  
Oxygen Desorption ◽  
The Past ◽  
Diffusion Controlled ◽  
Original Observation ◽  
Substantial Interest

Since the original observation that the surfaces of materials undergo radiation damage in the electron microscope similar to that observed by more conventional surface science techniques there has been substantial interest in understanding these phenomena in more detail; for a review see. For instance, surface damage in a microscope mimics damage in the space environment due to the solar wind and electron beam lithographic operations.However, purely qualitative experiments that have been done in the past are inadequate. In addition, many experiments performed in conventional microscopes may be inaccurate. What is needed is careful quantitative analysis including comparisons of the behavior in UHV versus that in a conventional microscope. In this paper we will present results of quantitative analysis which clearly demonstrate that the phenomena of importance are diffusion controlled; more detailed presentations of the data have been published elsewhere.As an illustration of the results, Figure 1 shows a plot of the shrinkage of a single, roughly spherical particle of WO3 versus time (dose) driven by oxygen desorption from the surface.

Bence-albee after 25 years: A new superior α-factor correction procedure for the quantitative analysis of oxides and silicates

1992 ◽  
Vol 50 (2) ◽  
pp. 1744-1745
Author(s):  
John T. Armstrong
Keyword(s):  
Quantitative Analysis ◽  
Electron Microprobe ◽  
Binary Systems ◽  
Correction Procedure ◽  
Geological Samples ◽  
The Past ◽  
Large Matrix ◽  
Computational Speed ◽  
Microprobe Data ◽  
Geological Sciences

One of the most cited papers in the geological sciences has been that of Albee and Bence on the use of empirical " α -factors" to correct quantitative electron microprobe data. During the past 25 years this method has remained the most commonly used correction for geological samples, despite the facts that few investigators have actually determined empirical α-factors, but instead employ tables of calculated α-factors using one of the conventional "ZAF" correction programs; a number of investigators have shown that the assumption that an α-factor is constant in binary systems where there are large matrix corrections is incorrect (e.g, 2-3); and the procedure’s desirability in terms of program size and computational speed is much less important today because of developments in computing capabilities. The question thus exists whether it is time to honorably retire the Bence-Albee procedure and turn to more modern, robust correction methods. This paper proposes that, although it is perhaps time to retire the original Bence-Albee procedure, it should be replaced by a similar method based on compositiondependent polynomial α-factor expressions.

scholarly journals Magnetometer in-flight offset accuracy for the BepiColombo spacecraft

2020 ◽  
Vol 38 (4) ◽  
pp. 823-832 ◽  
Author(s):  
Daniel Schmid ◽  
Ferdinand Plaschke ◽  
Yasuhito Narita ◽  
Daniel Heyner ◽  
Johannes Z. D. Mieth ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Observation Time ◽  
Space Environment ◽  
Method Performance ◽  
Mode Method ◽  
Magnetometer Data ◽  
Mirror Mode ◽  
Fluctuation Method

Abstract. Recently the two-spacecraft mission BepiColombo launched to explore the plasma and magnetic field environment of Mercury. Both spacecraft, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO, also referred to as Mio), are equipped with fluxgate magnetometers, which have proven to be well-suited to measure the magnetic field in space with high precision. Nevertheless, accurate magnetic field measurements require proper in-flight calibration. In particular the magnetometer offset, which relates relative fluxgate readings into an absolute value, needs to be determined with high accuracy. Usually, the offsets are evaluated from observations of Alfvénic fluctuations in the pristine solar wind, if those are available. An alternative offset determination method, which is based on the observation of highly compressional fluctuations instead of incompressible Alfvénic fluctuations, is the so-called mirror mode technique. To evaluate the method performance in the Hermean environment, we analyze four years of MESSENGER (MErcury Surface, Space ENvironment, GEophysics and Ranging) magnetometer data, which are calibrated by the Alfvénic fluctuation method, and compare it with the accuracy and error of the offsets determined by the mirror mode method in different plasma environments around Mercury. We show that the mirror mode method yields the same offset estimates and thereby confirms its applicability. Furthermore, we evaluate the spacecraft observation time within different regions necessary to obtain reliable offset estimates. Although the lowest percentage of strong compressional fluctuations are observed in the solar wind, this region is most suitable for an accurate offset determination with the mirror mode method. 132 h of solar wind data are sufficient to determine the offset to within 0.5 nT, while thousands of hours are necessary to reach this accuracy in the magnetosheath or within the magnetosphere. We conclude that in the solar wind the mirror mode method might be a good complementary approach to the Alfvénic fluctuation method to determine the (spin-axis) offset of the Mio magnetometer.

scholarly journals An operational solar wind prediction system transitioning fundamental science to operations

2018 ◽  
Vol 8 ◽  
pp. A39 ◽  
Author(s):  
Jingjing Wang ◽  
Xianzhi Ao ◽  
Yuming Wang ◽  
Chuanbing Wang ◽  
Yanxia Cai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Arrival Time ◽  
Space Environment ◽  
Maximum Speed ◽  
Source Surface ◽  
Prediction System ◽  
Fundamental Science ◽  
Cone Model ◽  
The Mean

We present in this paper an operational solar wind prediction system. The system is an outcome of the collaborative efforts between scientists in research communities and forecasters at Space Environment Prediction Center (SEPC) in China. This system is mainly composed of three modules: (1) a photospheric magnetic field extrapolation module, along with the Wang-Sheeley-Arge (WSA) empirical method, to obtain the background solar wind speed and the magnetic field strength on the source surface; (2) a modified Hakamada-Akasofu-Fry (HAF) kinematic module for simulating the propagation of solar wind structures in the interplanetary space; and (3) a coronal mass ejection (CME) detection module, which derives CME parameters using the ice-cream cone model based on coronagraph images. By bridging the gap between fundamental science and operational requirements, our system is finally capable of predicting solar wind conditions near Earth, especially the arrival times of the co-rotating interaction regions (CIRs) and CMEs. Our test against historical solar wind data from 2007 to 2016 shows that the hit rate (HR) of the high-speed enhancements (HSEs) is 0.60 and the false alarm rate (FAR) is 0.30. The mean error (ME) and the mean absolute error (MAE) of the maximum speed for the same period are −73.9 km s−1 and 101.2 km s−1, respectively. Meanwhile, the ME and MAE of the arrival time of the maximum speed are 0.15 days and 1.27 days, respectively. There are 25 CMEs simulated and the MAE of the arrival time is 18.0 h.

scholarly journals A magnetodisc model service for planetary space weather studies

2019 ◽  
Vol 9 ◽  
pp. A24
Author(s):  
Nicholas Achilleos ◽  
Patrick Guio ◽  
Nicolas André ◽  
Arianna M. Sorba
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Theoretical Models ◽  
Plasma Pressure ◽  
Space Environment ◽  
Solar Wind Flow ◽  
Physical Response ◽  
Global Magnetic Field ◽  
Upstream Solar Wind ◽  
Azimuthal Current

Theoretical models play an important role in the Planetary Space Weather Services (PSWS) of the European Planetary Network (“Europlanet”), due to their ability to predict the physical response of magnetospheric environments to compressions or rarefactions in the upstream solar wind flow. We illustrate this aspect by presenting examples of some calculations done with the UCL Magnetodisc Model in both “Jupiter” and “Saturn” mode. Similar model outputs can now be provided via the PSWS MAGNETODISC service. For each planet’s space environment, we present example model outputs showing the effect of compressions and rarefactions on the global magnetic field, plasma pressure and azimuthal current density. As a simple illustration of the physics underlying these reference models, we quantify solar wind effects by comparing the “compressed” and “expanded” outputs to a nominal “average-state” model, reflecting more typical solar wind dynamic pressures. We also describe the implementation of the corresponding PSWS MAGNETODISC Service, through which similar outputs may be obtained by potential users.

The Draft Fining Guidelines and the future of antitrust fines in China

2020 ◽  
Author(s):  
Su Sun ◽  
Chenying Zhang
Keyword(s):  
Quantitative Analysis ◽  
Major Part ◽  
Natural Question ◽  
Current Version ◽  
The Past ◽  
The Future ◽  
Antimonopoly Law ◽  
Case Decisions

Abstract Fines are a major part of the punishment and deterrence in China’s enforcement of its Antimonopoly Law. China has been drafting antitrust fining guidelines in the past several years and the current version is believed to be close to final. One natural question is: will the antitrust fining guidelines lead to harsher antitrust fines in China’s future enforcement? We attempt to answer this question by assessing whether fine recipients in China’s historical antitrust investigations would have received higher fines according to the Draft Fining Guidelines. Based on a large number of historical non-merger case decisions issued by China’s antitrust agencies through September 2019, our quantitative analysis shows that higher future fines should be expected in the future. We also explore several factors that might explain why historical fines were below the level predicted by the Draft Fining Guidelines.

A Review of the Relative Merits of Low Powered WDXRF and EDXRF Spectrometers for Routine Quantitative Analysis

1990 ◽  
Vol 34 ◽  
pp. 193-199
Author(s):  
B. J. Price ◽  
J. Padur ◽  
N. S. Robson
Keyword(s):  
Quantitative Analysis ◽  
Energy Resolution ◽  
Spectral Resolution ◽  
X Ray ◽  
The Past

Historically, the development of XRF spectrometers has followed 2 main paths which are characterized by the means of spectral resolution they use. Those employing diffraction crystals and Braggs law to disperse the X-ray wavelengths are known as wavelength dispersive (WDX), whilst those usinq only the energy resolution of the detector, as enerqy dispersive (EDX). In the past these two have not normally been directly compared, because the WDX systems have always been the more expensive.

DC Polarography of Cephradine and Its Application to Capsules

1979 ◽  
Vol 62 (3) ◽  
pp. 556-559
Author(s):  
Luis J Nuñez-Vergara ◽  
Juan A Squella ◽  
Ernesto M Gonzalez
Keyword(s):  
Quantitative Analysis ◽  
Spectral Data ◽  
Linear Relation ◽  
Dosage Forms ◽  
Polarographic Method ◽  
Acidic Hydrolysis ◽  
Diffusion Controlled ◽  
Dc Polarography ◽  
Coloring Matter

Abstract A polarographic method has been developed for the quantitative analysis of cephradine and its dosage forms. Direct determinations on capsules are carried out; excipients and coloring matter do not interfere in the determination. The electroactive product is formed by acidic hydrolysis with 5.0N HCl and heating at 80°C for 60 min. Two polarographic waves are obtained: I = - 0.46 v and II = - 0.78 v vs. SCE. Both reduction waves are diffusion controlled. Wave I is preferred for analytical purposes. The precise chemical identity of the electroactive product has not been determined, but UV spectral data and the TLC Rf value are reported. A linear relation is established for levels of cephradine between 10-2 and 10-5M in 5.0N HCl.

Fifty years with baskets

2020 ◽  
pp. 019769312096344
Author(s):  
James M Adovasio
Keyword(s):  
Comparative Study ◽  
50Th Anniversary ◽  
Technical Process ◽  
Multiple Points ◽  
Half Century ◽  
The Past ◽  
Artifact Analysis ◽  
Mechanical Factors ◽  
Points Of View ◽  
Original Observation

The year 2020 marks the 50th anniversary of my first publication on prehistoric basketry. Over the past five decades, the field of perishable artifact analysis has evolved dramatically. Though this evolution has not resulted in a geometric increase in the number of practitioners of this still arcane specialty, it has witnessed numerous transformations and enhancements of focus. After a half century and literally hundreds of publications, papers, and other perishable platitudes, my fundamental “message” continues to follow Weltfish’s original observation that basketry is valuable as a medium for comparative study from multiple points of view because as noted by Weltfish decades ago “the mechanical factors involved in the technical process objectify themselves in the product and are not lost in the process of making.” This contribution summarizes some of the major developments in the arena of basketry studies and, more broadly, in the field of perishable artifact analysis at large.

Modeling the X-ray emissions from the geo-space environment

2020 ◽  
Author(s):  
Tianran Sun
Keyword(s):  
Solar Wind ◽  
Excited State ◽  
Ground State ◽  
Heavy Ion ◽  
High Charge State ◽  
Space Environment ◽  
Neutral Component ◽  
X Ray ◽  
Working Groups ◽  
Solar Wind Charge Exchange

<p>The Earth's magnetosheath is luminous in the soft X-ray band, due to the solar wind charge exchange (SWCX) process. SWCX occurs when a heavy solar wind ion with a high charge state encounters with a neutral component. The heavy ion obtains an electron and gets into an excited state. It then decays to the ground state and emits a photon in the soft X-ray band. Considering that the X-ray emission from the magnetosheath is higher compared to that from the magnetosphere, information about the boundary positions can be derived from an X-ray image of the magnetosheath.</p><p> </p><p>The solar wind - magnetosphere - ionosphere link explorer (SMILE) is a mission jointly supported by ESA and CAS, which aims at exploring the dynamics in the whole system. Soft X-ray Imager (SXI) is expected to provide X-ray images of the magnetosphere. The Modeling Working Group (MWG) is one of the four working groups of SMILE. Studies about the modeling of X-ray emissions as well as the method to derive the boundary positions are two main topics of the MWG. The main progress of MWG will be summarized here. </p>

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