Is full computer automation of H.R.E.M. feasible?

1983 ◽  
Vol 41 ◽  
pp. 404-405
Author(s):  
O.L. Krivanek ◽  
P. Stadelmann ◽  
A. Higgs ◽  
C. Chen ◽  
M.M. Disko
Keyword(s):  
Computer Control ◽  
Computer Control System ◽  
Fibre Optics ◽  
Control Interface ◽  
Analog Control ◽  
Resolution Electron ◽  
Microscope Imaging ◽  
On Line ◽  
High Resolution Electron Microscope ◽  
Computer Automation

Recently it has become clear that a high resolution electron microscope (H.R.E.M.) can be controlled by a computer which "sees" the image via a TV camera connected to a digital framestore, and which "adjusts" the microscope imaging parameters via a D/A (Digital/Analog) control interface so as to optimize the image. The question therefore arises whether it will some day be possible to replace human microscope operators with inexpensive minicomputers capable of performing all the traditionally human tasks, but with much greater precision, repeatability, and speed.Fig. 1 shows a schematic of the computer control system for a JEM 200CX HREM under development at ASU. The TV camera is coupled via a 2:1 reducing fibre- optics bundle to a P22 phosphor screen as described previously. The DeAnza framestore has enough memory for up to four 512x512x8 bit images, and can perform various simple operations such as adding or subtracting two images at TV rates (on-line).

scholarly journals On-Line Computer Control System for Greenhouses under High Radiation and Temperature Zones

1985 ◽  
Author(s):  
James W. Jones ◽  
Ehude Dayan ◽  
Pierce H. Jones ◽  
Zvi Enoch ◽  
Leon Hartwell Allen, Jr. ◽  
...  
Keyword(s):  
Control System ◽  
Computer Control ◽  
Computer Control System ◽  
High Radiation ◽  
On Line

A Computer Control System for the Hydraulic Stand MZPK 100 for Biaxial Fatigue Testing

2006 ◽  
Vol 113 ◽  
pp. 13-18 ◽  
Author(s):  
L.M. Kasprzyczak ◽  
J.R. Słowik ◽  
Ewald Macha
Keyword(s):  
Control System ◽  
Digital Control ◽  
Fatigue Testing ◽  
Biaxial Tension ◽  
Computer Control ◽  
Fatigue Tests ◽  
Digital Control System ◽  
Computer Control System ◽  
Biaxial Fatigue ◽  
Analog Control

This paper presents a two-channel digital control system for the hydraulic stand MZPK 100 designed for fatigue tests of cruciform specimens under biaxial tension-compression. In the past, the fatigue test stand MZPK 100 was provided with unreliable analog control power cubicles. Application of the computer with an analog and digital input-output signal path board, Matlab/Simulink software and a new control box equipped with the necessary electronic subassemblies (responsible for proper switching of the hydraulic supplier, command electrovalves, conditioning of signals from sensors and so on) enables replacement of the old analog system by a new two-channel digital control system. Nowadays, it is easy to modify the control system to different requirements of material tests because the hardware (electronic) solutions have been simplified, and the software has a friendly Simulink interface. Such an approach allows for the implementation of different control algorithms, e.g. PID, adaptive, and fuzzy logic etc. Moreover, this paper presents a description of how to keep the center of the specimen static under a controlled force that is being applied by four independent actuators.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 486-487
Author(s):  
Mihir Parikh
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Cross Sections ◽  
Resolving Power ◽  
Peak Intensity ◽  
Molecular Film ◽  
Resolution Electron ◽  
Dissociation Cross Section ◽  
High Resolution Electron Microscope ◽  
The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

Atomic-level imaging of the surface structure of Ag2O

1984 ◽  
Vol 42 ◽  
pp. 656-657
Author(s):  
William Krakow
Keyword(s):  
High Vacuum ◽  
Atomic Level ◽  
Ultra High Vacuum ◽  
Research Groups ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Order Of Magnitude ◽  
High Resolution Electron Microscope ◽  
Saturated Structure ◽  
Transmission And Reflection

In recent years electron microscopy has been used to image surfaces in both the transmission and reflection modes by many research groups. Some of this work has been performed under ultra high vacuum conditions (UHV) and apparent surface reconstructions observed. The level of resolution generally has been at least an order of magnitude worse than is necessary to visualize atoms directly and therefore the detailed atomic rearrangements of the surface are not known. The present author has achieved atomic level resolution under normal vacuum conditions of various Au surfaces. Unfortunately these samples were exposed to atmosphere and could not be cleaned in a standard high resolution electron microscope. The result obtained surfaces which were impurity stabilized and reveal the bulk lattice (1x1) type surface structures also encountered by other surface physics techniques under impure or overlayer contaminant conditions. It was therefore decided to study a system where exposure to air was unimportant by using a oxygen saturated structure, Ag2O, and seeking to find surface reconstructions, which will now be described.

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

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