The use of a high-speed digital computer for the direct determination of crystal structures. II

1957 ◽  
Vol 243 (1233) ◽  
pp. 281-288 ◽  
Keyword(s):  
High Speed ◽  
Electronic Computer ◽  
Direct Determination ◽  
Preceding Paper ◽  
Contour Maps ◽  
Unknown Structure ◽  
New Criterion ◽  
High Degree ◽  
Selection Of

This paper discusses some possible procedures for crystal structure determination using the X criterion developed in the preceding paper of the series. In that paper it was shown that, under favourable circumstances, the signs of the largest terms in the Fourier series representa­tion of ρ , the electron density in the unit cell, can be determined directly. The magnitudes of these terms can be found by experiment. In less favourable cases the correct set of signs, to a high degree of probability, lies among several hundred possible sets which can be determined by the processes described. A new criterion is proposed for selection of a lesser number, say a dozen, ‘most probable’ sets of signs. These latter sets can be tested by inspection of the corre­sponding contour maps of ρ . The new criterion has been successfully used in determining the unknown structure of nitroguanidine. Techniques for the selection of most probable sets and also for evaluation of ρ at suitable points in space using an electronic computer, the EDSAC, are described.

The use of a high-speed digital computer for the direct determination of crystal structures. I

1955 ◽  
Vol 227 (1171) ◽  
pp. 486-500 ◽  
Keyword(s):  
Crystal Structure ◽  
Fourier Series ◽  
Crystal Structures ◽  
Digital Computer ◽  
High Speed ◽  
Electronic Computer ◽  
Direct Determination ◽  
Direct Methods ◽  
Weighting Factor

A method is described whereby an electronic computer, the EDSAC, may be used to select a set, or sets, of signs for the coefficients F (h) of a Fourier series, such that the Fourier series, satisfies a certain condition. This condition is expressed as X ≡ Ʃ h Ʃ h ' P (h,h') S (h) S (h') S (h+h')≽ X 0 , where S (h) denotes the sign of F (h) and P (h, h') is a weighting factor related to the probability that S (h) S (h') = S (h+h'). In certain circumstances the determination of a crystal structure which is beyond the range of other direct methods is possible by this procedure.

scholarly journals Determination of the optimal curvature of the turnout diverging track for HSR using dynamic analysis

2017 ◽  
Vol 2017 (10) ◽  
pp. 1-11
Author(s):  
Władysław Koc ◽  
Katarzyna Palikowska
Keyword(s):  
Dynamic Analysis ◽  
Analytical Method ◽  
High Speed ◽  
Extreme Points ◽  
Point Of View ◽  
High Speed Railway ◽  
Zero Values ◽  
Linear And Nonlinear ◽  
Selection Of

The paper presents an analytical method of identifying the curvature of the turnout diverging track consisting of sections of varying curvature. Such turnout is mainly applied on High Speed Railway. Both linear and nonlinear (polynomial) curvatures of the turnout diverging track are considered in the paper. Obtained solutions enable to assume curvature values at the beginning and end point of the geometrical layout of the turnout.The paper focus on a fundamental and unexplained so far issue connected with selection of the most favourable curvature section from the operational requirements point of view. In order to determine the optimal curvature a dynamic analysis has been carried out on the several representative cases. It has been indicated that, used in railway practice, clothoid sections with nonzero curvatures at the beginning and end points of the turnout should be verified. It has been proved that the turnout with nonlinear curvature reaching zero values at the extreme points of the geometrical layout is the most favourable.

scholarly journals RECYCLING OF CONSTRUCTION WASTE USING HIGH-SPEED MILLING PROCESS: DETERMINATION OF WASTE CONCRETE

2019 ◽  
Vol 22 ◽  
pp. 88-93
Author(s):  
Zdeněk Prošek ◽  
Pavel Tesárek ◽  
Jan Trejbal ◽  
Tereza Horová
Keyword(s):  
High Speed ◽  
Direct Determination ◽  
Microscopic Analysis ◽  
Mechanical Tests ◽  
Milling Process ◽  
High Speed Milling ◽  
X Ray ◽  
Waste Concrete ◽  
Recycled Material

This paper deals with the use of high-speed milling process for recycling old concrete and direct determination of the potential of input waste. For this purpose, three different types of waste concrete were used: prefabricated railway sleeper, structural concrete of monolithic pillar and prefabricated drainage gutter. The paper directly examines the chemical and phase composition by XRF, X-Ray Diffraction (XRD), Energy Dispersive X-ray Spectrometry (EDS) and microscopic analysis, particle size distribution and pH of the recycled material. Results of those analysis are used to select suitable recycled material. The suitability of choice is supported by mechanical tests of 28-day old cement pastes, where the compressive strength and dynamic modulus of elasticity are observed properties. Specimens measuring 40 × 40 × 160mm are composed of 70 wt.% Portland cement and rest is micronized concrete. In all cases, the results are compared with the reference material.

The Oxidation Products of Rubber

1939 ◽  
Vol 12 (2) ◽  
pp. 225-234
Author(s):  
A. van Rossem ◽  
P. Dekker
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Tensile Properties ◽  
High Speed ◽  
Accelerated Aging ◽  
Direct Determination ◽  
Oxidation Products ◽  
Vulcanized Rubber

Abstract In their summary of the aging of vulcanized rubber, Porritt and Scott state that three factors are responsible for the changes in mechanical properties of vulcanized rubber during aging, viz.: (a) oxidation of the rubber; (b) after-vulcanization; (c) some colloidal change of the rubber, sometimes termed aggregation. Of these factors, oxidation is by far the most important because it is responsible for the decrease in mechanical properties, which leads to the general deterioration of rubber from a technical standpoint. It was Marzetti who proved that the decrease of mechanical properties in accelerated aging is due to oxidation. Later, Kohman confirmed this in a more concise way and showed that even such small amounts as 0.5% of oxygen absorbed by vulcanized rubber are sufficient to decrease tensile properties to 50% of their original value. When studying aging, three ways of tackling this problem are possible, viz.: (1) Investigations of the mechanical properties, either under normal conditions, or under special conditions such as elevated temperature or high speed. (2) Determination of oxidation products, which are formed during oxidation of the rubber. (3) Direct determination of the amount of oxygen which is absorbed by the rubber. It is clear that any of these methods may be combined with accelerated aging tests.

Direct determination of astragalosides and isoflavonoids from fresh Astragalus membranaceus hairy root cultures by high speed homogenization coupled with cavitation-accelerated extraction followed by liquid chromatography-tandem mass spectrometry

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34672-34681 ◽  
Author(s):  
Jiao Jiao ◽  
Qing-Yan Gai ◽  
Meng Luo ◽  
Xiao Peng ◽  
Chun-Jian Zhao ◽  
...  
Keyword(s):  
High Speed ◽  
Direct Determination ◽  
Metabolic Profiles ◽  
Tandem Mass ◽  
Hairy Root Cultures ◽  
Root Cultures ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

HSH-CAE-LC-MS/MS opened up a new avenue for the direct determination of secondary metabolic profiles from fresh plant in vitro cultures.

scholarly journals The Use of Connected Masks for Reconstructing the Single Particle Image from X-Ray Diffraction Data. III. Maximum-Likelihood Based Strategies to Select Solution of the Phase Problem

2017 ◽  
Vol 12 (2) ◽  
pp. 521-535 ◽  
Author(s):  
Н.Л. Лунина ◽  
N.L. Lunina
Keyword(s):  
Bragg Diffraction ◽  
Biological Macromolecules ◽  
Phase Problem ◽  
X Ray Diffraction ◽  
Additional Advantage ◽  
X Ray ◽  
Experimental Limitation ◽  
New Criterion ◽  
Selection Of

The main experimental limitation of biological crystallography is associated with the need to prepare the object under study in the form of a single crystal. New powerful X-ray sources, namely free-electron X-ray lasers, makes it possible to raise the question of the determination of the structure of isolated biological macromolecules and their complexes in practice. An additional advantage of working with isolated particles is the possibility to obtain information about scattering in all directions, and not only in those limited by the Laue-Bragg diffraction conditions. This significantly facilitates the solution of the phase problem of X-ray diffraction analysis. This paper is devoted to two lines of development of the method for solving the phase problem, proposed earlier by the authors, which is based on the random scanning of the configuration space of potential solutions of the phase problem. The paper suggests a new criterion for the selection of "candidates" for solving the phase problem in the process of scanning. It involves the maximization of statistical likelihood, and its effectiveness is shown in test calculations. The second line concerns the choice of the optimal scanning strategy. It is shown that the gradual expansion of the set of experimental data used in the work allows obtaining solutions of a higher quality than those obtained with all available data included into the work simultaneously from the beginning.

Direct determination of cobalt in unpurged oceanic seawater by high speed adsorptive cathodic stripping voltammetry

1994 ◽  
Vol 299 (1) ◽  
pp. 59-67 ◽  
Author(s):  
J.A. Herrera-Melián ◽  
J. Hernández-Brito ◽  
M.D. Gelado-Caballero ◽  
J. Pérez-Peña
Keyword(s):  
High Speed ◽  
Direct Determination ◽  
Stripping Voltammetry ◽  
Cathodic Stripping Voltammetry ◽  
Cathodic Stripping

scholarly journals Tactics and Technology of Non-Verbal Investigative Actions Production in Computer Crimes Cases: Theory and Practice

Lex Russica ◽  
2021 ◽  
pp. 102-118
Author(s):  
E. R. Rossinskaya ◽  
I. A. Ryadovskiy
Keyword(s):  
High Speed ◽  
Theory And Practice ◽  
Basic Principles ◽  
Technological Support ◽  
Tactical Decision ◽  
Computer Crimes ◽  
Computer Forensic ◽  
Judicial Actions ◽  
Selection Of

The paper considers the doctrine of information and computer forensic support of investigative and judicial actions tactics, which is part of the system of the private theory of information and computer support of forensic activity. The subject of the teaching is the laws of gathering, scrutinizing and applying computer information in the production of investigative and judicial actions. The objects are the tactics and technology of investigative and judicial actions. Based on the theoretical aspects of the teaching, the authors have developed the tactics and technology of non-verbal investigative actions in cases of computer crimes. Among these are inspection of the scene of the crime, search, seizure, investigative experiment, given the choice of tactical impact and making a tactical decision depending on the specifics of investigative situations in the conditions of tactical risk associated with possible counteraction to the investigation. The tactical and technological support for the production of the above-mentioned non-verbal investigative actions is developed taking into account the features of digital traces, which are characterized by a high speed of transformation, are easily destroyed and modified, can be represented by an almost infinite number of copies, are characterized by the impossibility of perception directly by the senses, but only with the use of special devices and programs for detection, fixation and preservation, are confirmed by control numbers (hash sums) or other data indicating their integrity. The basic principles of working with digital traces in the production of non-verbal investigative actions are determined. They are the preservation of digital traces unchanged at all stages of working with them; full reflection of all manipulations in the protocols of investigative actions; the exceptional importance of preparatory measures, including the selection of a specialist and the determination of his competence, the availability of the necessary equipment and software for working with digital traces. For each of the above-mentioned investigative actions in the investigation of computer crimes, tactical techniques and technological support for the most effective obtaining of criminally significant evidentiary and investigative information have been developed.

REFERENCE MATERIALS FOR MICRO-ANALYTICAL NUCLEAR TECHNIQUES

1992 ◽  
Vol 02 (04) ◽  
pp. 651-664 ◽  
Author(s):  
V. Valkovic ◽  
R. Zeisler ◽  
G. Bernasconi ◽  
P.R. Danesi
Keyword(s):  
Trace Elements ◽  
Reference Materials ◽  
Analytical Techniques ◽  
X Ray ◽  
Ion Probe ◽  
Low Levels ◽  
Analytical Procedures ◽  
High Degree ◽  
Selection Of

Direct application of many existing reference materials in micro-analytical procedures such as energy dispersive x-ray fluorescence (EDXRF), particle induced x-ray emission spectroscopy (PIXE) and ion probe techniques for the determination of trace elements is often impossible or difficult because: 1) other constituents present in large amounts interfere with the determination; 2) trace components are not sufficiently homogeneously distributed in the sample. Therefore specific natural-matrix reference materials containing very low levels of trace elements and having high degree of homogeneity are required for many micro-analytical procedures. In this report, selection of the types of environmental and biological materials which are suitable for micro-analytical techniques will be discussed.

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