scholarly journals Mutation operators in lens system optimization to jump out of local minima

2010 ◽  
Vol 18 (20) ◽  
pp. 20876 ◽  
Author(s):  
Lei Li ◽  
Qiong-Hua Wang ◽  
Xiao-Qing Xu ◽  
Da-Hai Li
Keyword(s):  
System Optimization ◽  
Local Minima ◽  
Lens System ◽  
Mutation Operators

Mutated and converged damping factors in lens system optimization to find new local minima

Optik ◽  
2013 ◽  
Vol 124 (20) ◽  
pp. 4150-4154 ◽  
Author(s):  
Lei Li ◽  
Xiao-Qing Xu ◽  
Qiong-Hua Wang
Keyword(s):  
System Optimization ◽  
Local Minima ◽  
Lens System

Finding new local minima by switching merit functions in optical system optimization

2005 ◽  
Vol 44 (10) ◽  
pp. 100501 ◽  
Author(s):  
Alexander Serebriakov ◽  
Florian Bociort ◽  
Joseph Braat
Keyword(s):  
Optical System ◽  
System Optimization ◽  
Local Minima ◽  
Merit Functions

Finding improved local minima of power system optimization problems by interior-point methods

2003 ◽  
Vol 18 (1) ◽  
pp. 238-244 ◽  
Author(s):  
J. Riquelme Santos ◽  
A. Troncoso Lora ◽  
A. Gomez Expisito ◽  
J.L. Martinez Ramos
Keyword(s):  
Power System ◽  
Interior Point ◽  
Interior Point Methods ◽  
Optimization Problems ◽  
System Optimization ◽  
Local Minima ◽  
Power System Optimization

Networks of local minima in optical system optimization

2004 ◽  
Vol 29 (2) ◽  
pp. 189 ◽  
Author(s):  
Florian Bociort ◽  
Eco van Driel ◽  
Alexander Serebriakov
Keyword(s):  
Optical System ◽  
System Optimization ◽  
Local Minima

A modified genetic algorithm for system optimization

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alexander Zemliak
Keyword(s):  
Genetic Algorithm ◽  
Fitness Function ◽  
System Optimization ◽  
High Accuracy ◽  
Optimization Process ◽  
Processing Unit ◽  
Local Minima ◽  
Control Vector ◽  
Content Type ◽  
Cpu Time

Purpose In this paper, the previously developed idea of generalized optimization of circuits for deterministic methods has been extended to genetic algorithm (GA) to demonstrate new possibilities for solving an optimization problem that enhance accuracy and significantly reduce computing time. Design/methodology/approach The disadvantages of GAs are premature convergence to local minima and an increase in the computer operation time when setting a sufficiently high accuracy for obtaining the minimum. The idea of generalized optimization of circuits, previously developed for the methods of deterministic optimization, is built into the GA and allows one to implement various optimization strategies based on GA. The shape of the fitness function, as well as the length and structure of the chromosomes, is determined by a control vector artificially introduced within the framework of generalized optimization. This study found that changing the control vector that determines the method for calculating the fitness function makes it possible to bypass local minima and find the global minimum with high accuracy and a significant reduction in central processing unit (CPU) time. Findings The structure of the control vector is found, which makes it possible to reduce the CPU time by several orders of magnitude and increase the accuracy of the optimization process compared with the traditional approach for GAs. Originality/value It was demonstrated that incorporating the idea of generalized optimization into the body of a stochastic optimization method leads to qualitatively new properties of the optimization process, increasing the accuracy and minimizing the CPU time.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Slow-Scan CCD Observation of Backscattering Patterns in SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1308-1309
Author(s):  
F. Ouyang ◽  
D. A. Ray ◽  
O. L. Krivanek
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Lens System ◽  
Wide Dynamic Range ◽  
Peltier Cooler ◽  
Diffraction Patterns ◽  
Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

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