The IEEE 1584-2002 Arc Modeling Debate and Simple Incident Energy Equations for Low-Voltage Systems

2006 ◽  
Author(s):  
T. Gammon ◽  
J. Matthews
Keyword(s):  
Incident Energy ◽  
Low Voltage ◽  
Energy Equations

Physical Considerations in Low Energy Biological Analysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 302-303 ◽  
Author(s):  
David C Joy
Keyword(s):  
Periodic Table ◽  
Incident Energy ◽  
Low Voltage ◽  
Energy Dispersive Spectrometer ◽  
Incident Beam ◽  
X Ray ◽  
Upper Limit ◽  
Physical Effects ◽  
Fundamental Physical ◽  
Critical Excitation

Biological scanning electron microscopy is increasingly performed at low beam energies in order to improve image contrast, reduce charging artifacts, and minimize beam induced damage to the sample. It is natural then to wish to also use these same low accelerating voltage for X-ray microanalysis using an energy dispersive spectrometer (EDS) but a variety of fundamental physical effects affect the performance that can be achieved. An X-ray photon can only be emitted when the incident beam Eo energy exceeds the critical excitation energy Ecrit for that line. As the beam energy is reduced the number of elements that can be excited falls and it is becomes necessary to use L- and M-lines rather than the K-lines accessible at higher energies. At 5keV, the upper limit of ‘low voltage’ microscopy, K-lines can be excited from elements up to calcium, L-lines can be detected up to cesium, and the rest of the periodic table is available using M-lines. The entire periodic table is therefore, in principle, available at an overvoltage U>2, where U = E0/Ecrit But at lower energies the number of accessible excitations falls and some elements cannot, with current technology, then be analyzed and for general purposes an incident energy lower than about 3keV is probably too limiting to be useful.

scholarly journals Changeability of arc flash parameters and its impact on hazard mitigation in low voltage power systems

2021 ◽  
Author(s):  
Abdeslem Kadri
Keyword(s):  
Power Systems ◽  
Incident Energy ◽  
Low Voltage ◽  
Hazard Mitigation ◽  
Research Work ◽  
Work Place ◽  
Mathematical Basis ◽  
System Parameters ◽  
Arc Flash ◽  
The Impact

Arc flashes in power system result in a huge amount of incident energy that can injure human workers. Strict safety measures have to be applied in the work place for safety of technical personnel. Computation of the incident energy is imperative to determine the corresponding safety requirements. Arcing current, and hence incident energy, is a function of some system parameters which may vary due to different reasons. This research work considers the problem of parameter variability in arc flash calculations and its effect on hazard mitigation. A mathematical basis is set forth for the impact of the variation in gap between electrodes and system voltage on the incident energy value. Findings of this work emphasize that small variations in system parameters can yield inaccurate values of incident energy and misleading hazard categories. Therefore, parameter variation has to be carefully accommodated in the arc flash calculations to result in the proper hazard mitigation precautions.

scholarly journals Changeability of arc flash parameters and its impact on hazard mitigation in low voltage power systems

2021 ◽  
Author(s):  
Abdeslem Kadri
Keyword(s):  
Power Systems ◽  
Incident Energy ◽  
Low Voltage ◽  
Hazard Mitigation ◽  
Research Work ◽  
Work Place ◽  
Mathematical Basis ◽  
System Parameters ◽  
Arc Flash ◽  
The Impact

Arc flashes in power system result in a huge amount of incident energy that can injure human workers. Strict safety measures have to be applied in the work place for safety of technical personnel. Computation of the incident energy is imperative to determine the corresponding safety requirements. Arcing current, and hence incident energy, is a function of some system parameters which may vary due to different reasons. This research work considers the problem of parameter variability in arc flash calculations and its effect on hazard mitigation. A mathematical basis is set forth for the impact of the variation in gap between electrodes and system voltage on the incident energy value. Findings of this work emphasize that small variations in system parameters can yield inaccurate values of incident energy and misleading hazard categories. Therefore, parameter variation has to be carefully accommodated in the arc flash calculations to result in the proper hazard mitigation precautions.

Processing of human melanoma cells for correlative TEM, LVSEM, and LM

1991 ◽  
Vol 49 ◽  
pp. 106-107
Author(s):  
Marek Malecki ◽  
J. Victor Small ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Fluorescent Microscopy ◽  
Blood Stream ◽  
Surface Topology ◽  
Integrin Receptors ◽  
Transmission Electron ◽  
Develop Technology ◽  
Voltage Scanning ◽  
Mechanisms Of Adhesion

The relative roles of adhesion and locomotion in malignancy have yet to be clearly established. In a tumor, subpopulations of cells may be recognized according to their capacity to invade neighbouring tissue,or to enter the blood stream and metastasize. The mechanisms of adhesion and locomotion are themselves tightly linked to the cytoskeletal apparatus and cell surface topology, including expression of integrin receptors. In our studies on melanomas with Fluorescent Microscopy (FM) and Cell Sorter(FACS), we noticed that cells in cultures derived from metastases had more numerous actin bundles, then cells from primary foci. Following this track, we attempted to develop technology allowing to compare ultrastructure of these cells using correlative Transmission Electron Microscopy(TEM) and Low Voltage Scanning Electron Microscopy(LVSEM).

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Sign in / Sign up

Export Citation Format

Share Document