A Dynamic Timing Error Avoidance Technique Using Prediction Logic in High-Performance Designs

2019 ◽  
Vol 27 (3) ◽  
pp. 734-737
Author(s):  
Mehrnaz Ahmadi ◽  
Sahand Salamat ◽  
Bijan Alizadeh
Keyword(s):  
High Performance ◽  
Timing Error ◽  
Prediction Logic ◽  
Error Avoidance

scholarly journals Neural Flip-Flops II: Short-Term Memory and Electroencephalography

2020 ◽  
Author(s):  
Lane Yoder
Keyword(s):  
Short Term Memory ◽  
Building Blocks ◽  
Short Term ◽  
Timing Error ◽  
Term Memory ◽  
Frequency Bands ◽  
Brain Functions ◽  
Delay Times ◽  
The Mean ◽  
Error Avoidance

AbstractFor certain brain functions, the theoretical networks presented here almost certainly show how neurons are actually connected. Stripped of details such as redundancies and other error-correcting mechanisms, the basic organization of synaptic connections within some of the brain’s building blocks is likely to be less complex than it appears. For some brain functions, the network architectures can even be quite simple.Flip-flops are the basic building blocks of sequential logic systems. Certain flip-flops can be configured to function as oscillators. The flip-flops and oscillators proposed here are composed of two to six neurons, and their operation depends only on minimal neuron capabilities of excitation and inhibition. These networks suggest a resolution to the longstanding controversy of whether short-term memory depends on neurons firing persistently or in brief, coordinated bursts. Oscillators can also generate major phenomena of electroencephalography.For example, cascaded oscillators can produce the periodic activity commonly known as brainwaves by enabling the state changes of many neural structures simultaneously. (The function of such oscillator-induced synchronization in information processing systems is timing error avoidance.) Then the boundary separating the alpha and beta frequency bands is where μd and σd are the mean and standard deviation (in milliseconds) of delay times of neurons that make up the initial oscillators in the cascades. With 4 and 1.5 ms being the best estimates for μd and σd, respectively, this predicted boundary value is 14.9 Hz, which is within the range of commonly cited estimates obtained empirically from electroencephalograms (EEGs). The delay parameters μd = 4 and σd = 1.5 also make predictions of the peaks and other boundaries of the five major EEG frequency bands that agree well with empirically estimated values.The hypothesis that cascaded oscillators produce EEG frequencies implies two EEG characteristics with no apparent function: The EEG gamma band has the same distribution of frequencies as three-neuron ring oscillators, and the ratios of peaks and boundaries of the major EEG bands are powers of two. These anomalous properties make it implausible that EEG phenomena are produced by a mechanism that is fundamentally different from cascaded oscillators.The cascaded oscillators hypothesis is supported by the available data for neuron delay times and EEG frequencies; the micro-level explanations of macro-level phenomena; the number, diversity, and precision of predictions of EEG phenomena; the simplicity of the oscillators and minimal required neuron capabilities; the selective advantage of timing error avoidance that cascaded oscillators can provide; and the implausibility of a fundamentally different mechanism producing the phenomena.The available data are too imprecise for a rigorous statistical test of the cascaded oscillators hypothesis. A simple, rigorous test of the hypothesis is suggested. The neuron delay parameters μd and σd, as well as the mean and variance of the periods of one or more EEG bands, can be estimated from random samples. With standard tests for equal means and variances, the EEG sample statistics can be compared to the EEG parameters predicted by the delay time statistics.

A High Performance Energy Analyzer for Use in Electron Scanning Microscopy

1969 ◽  
Vol 27 ◽  
pp. 14-15
Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
High Performance ◽  
Vertical Plane ◽  
Median Plane ◽  
Electron Gun ◽  
Uniform Field ◽  
Loss Mechanism ◽  
Electron Scanning Microscopy ◽  
Sector Type ◽  
Double Focusing ◽  
Electron Energy Loss

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

Current State of Biological High-Resolution Scanning Electron Microscopy

1988 ◽  
Vol 46 ◽  
pp. 180-181 ◽  
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Performance ◽  
Low Voltage ◽  
Backscattered Electrons ◽  
Lens Position ◽  
Low Voltage Operation ◽  
Signal Collection ◽  
Probe Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).

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