scholarly journals The Determination of Affinity Distributions: A Numerical Algorithm and its Application for Estimating the Energetic Heterogeneity of Complexing Silicas and Humic Substances

2000 ◽  
Vol 18 (3) ◽  
pp. 267-294 ◽  
Author(s):  
Yu. Kholin ◽  
S. Myerniy ◽  
G. Varshal
Keyword(s):  
Electrostatic Interactions ◽  
Distribution Functions ◽  
Differential Distribution ◽  
Chemically Modified ◽  
Energetic Heterogeneity ◽  
Ill Posed ◽  
Integral Distribution ◽  
Methodological Difficulties

The characterization of energetic heterogeneity has been discussed in the investigation of ion-binding and chemisorption processes. Both the calculation and the interpretation of the distribution of affinity constants are ambiguous. Methodological difficulties arise connected to the fact that electrostatic effects are difficult to separate from energetic heterogeneity because of the chemical biography of a given material. Only a close similarity between the distribution functions calculated for different ionic strengths allows the electrostatic interactions to be neglected. The numerical estimation of the distribution functions is complicated by the ill-posed nature of the problem. Some computational methods are briefly compared and methods for providing robust and unbiased estimations outlined. In contrast to differential distribution functions, the computation of integral ones may be transformed into the conventionally correct problem. On this basis, a fast and robust method for calculating integral distribution functions is proposed. In addition, this ensures numerically stable estimations of differential distribution functions. The method has been applied to a study of the energetic heterogeneity of 20 silicas chemically modified with aliphatic amines. When H+ ions are chemisorbed, the energetic heterogeneity observed is dependent on the surface topography and its hydration state. In addition, the binding properties of ashless fulvic and humic acids relative to H+, Hg2+ and Pb2+ ions have been examined. The existence of functional groups with different acidities and complexing abilities has been established.

Differential Anomalous X-Ray Scattering Techniques for Determination of Liquid and Amorphous Structures

1985 ◽  
Vol 57 ◽  
Author(s):  
W. K. Warburton ◽  
K. F. Ludwig ◽  
L. Wilson ◽  
A. Bienenstock
Keyword(s):  
Structural Models ◽  
Distribution Functions ◽  
Anomalous Scattering ◽  
Differential Distribution ◽  
X Ray ◽  
Amorphous Systems ◽  
X Ray Scattering ◽  
Scattering Technique ◽  
Amorphous Structures

AbstractThe differential anomalous scattering technique is outlined and compared to other techniques for studying short-range order in amorphous systems, such as EXAFS. The differential distribution functions obtained for liquid GeBr4 were found to support a model for the liquid state based on the structure of the h.c.p. crystal. Application of the technique to aqueous ZnBr2 also allowed discr imination between structural models.

Determination of Structure, Shape and Sizes of Clusters Using Radial Distribution Functions (RDF) Method

1992 ◽  
Vol 272 ◽  
Author(s):  
Pavel E. Kolosov ◽  
A. V. Bubnov
Keyword(s):  
Distribution Functions ◽  
Structure Characterization ◽  
Radial Distribution Functions ◽  
Experimental Conditions ◽  
Interatomic Distances ◽  
X Ray ◽  
Molybdenum Sulfides ◽  
X Ray Scattering

ABSTRACTThe theoretical reduced intensity of X-ray scattering i(S) may be calculated for a cluster of any structure using Debye's formula. The comparison of both experimental determination and model calculation of the RDF or i(S) allows, to make a conclusions about structure of materials in a wide region of interatomic distances. This is a very important for direct structure characterization of giant clusters, dispersed molybdenum sulfides etc.. The simple formula for the upper limit of interatomic distances when the data are collected at equidistant step on S – scatterinrg vector, may be used for the optimal experimental conditions selection.

scholarly journals IDENTIFICATION OF THE DISTRIBUTION FUNCTION AND CHARACTERIZATION OF THE NANO– AND MICROPOWDERS SIZES

2021 ◽  
pp. 231-239
Author(s):  
И.С. Бондарчук ◽  
С.С. Титов ◽  
С.С. Бондарчук
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Inverse Problems ◽  
Efficient Algorithms ◽  
Distribution Functions ◽  
Differential Distribution ◽  
Program Code ◽  
Lognormal Distributions ◽  
Short Program

В работе предлагаются два новых эффективных алгоритма, реализованных коротким программным кодом в MS Excel, предназначенных для идентификации и характеризации размеров нано– и микропорошков частиц в виде обобщенного гамма или логнормального распределений по данным опытных гистограмм. Предлагаемый метод представляет собой новый и достаточно общий подход к решению обратных задач идентификации параметров дифференциальных функций распределения по экспериментальным данным на основе на минимизации функционала, представляющего собой коэффициент детерминации.Алгоритм реализован формулами (менее 10) наиболее распространенного инструментария (электронных таблиц MS Excel без использования макросов), позволяющего исследователям, не обладающими навыками профессиональных программистов, простоту проверки и воспроизведения представленного материала, а также возможность модификации кода для решения более широкого круга задач. Текст статьи и комментарии на рабочих листах скриншотов представляют собой готовые инструкции по решению задач идентификация функций распределения и характеризации размеров нано– и микропорошков. The paper proposes two new efficient algorithms, implemented by a short program code in MS Excel, designed to identify and characterize the sizes of nano- and micropowders of particles in the form of generalized gamma or lognormal distributions according to experimental histograms. The proposed method is a new general approach to solving inverse problems of identifying the parameters of differential distribution functions from experimental data based on minimizing the functional that is the coefficient of determination.The algorithm is implemented with formulas (less than 10) of the most common tools (MS Excel spreadsheets without the use of macros), which allow researchers without the skills of professional programmers to easily check and reproduce the presented material, as well as the ability to modify the code to solve a wider range of problems. The text of the article and comments on the worksheets of screenshots represent ready-made instructions for solving problems of identification of distribution functions and characterization of the sizes of nano- and micropowders.

Structural determination of amorphous Ti-Ni alloys

1984 ◽  
Vol 42 ◽  
pp. 508-509
Author(s):  
A. R. Pelton ◽  
P. Moine ◽  
R. Sinclair
Keyword(s):  
Amorphous Alloys ◽  
Structural Investigation ◽  
Distribution Functions ◽  
Atomic Processes ◽  
Statistical Characterization ◽  
X Ray ◽  
Ni Alloys ◽  
Amorphous Structures

Amorphous Ti-Ni alloys may be prepared by a variety of techniques, including: liquid quenching, ion implantation, electron irradiation, and vapor synthesis. Each of these techniques involves fundamentally different atomic processes with concomitant different effective quench rates. Since quench rates affect the degree of structural order, it is conceivable that a variety of metastable configurational states may thus result. Radial distribution functions (RDF’s) from diffraction experiments are a generally accessible probe for statistical characterization of amorphous alloys, and hence, a useful tool to compare amorphous structures. However, not all of the amorphization methods are capable of producing sufficient quantities of material required for x-ray or neutron scattering. Therefore, the purpose of this paper is to report the preliminary results from a comparative structural investigation of Ti-Ni alloys by x-ray and electron diffraction.

Information and estimation in image processing

1987 ◽  
Vol 45 ◽  
pp. 14-17
Author(s):  
B. Roy Frieden
Keyword(s):  
Image Processing ◽  
Optical System ◽  
Large Amplitude ◽  
Communication Theory ◽  
Image Data ◽  
Direct Approach ◽  
Ill Posed

Despite the skill and determination of electro-optical system designers, the images acquired using their best designs often suffer from blur and noise. The aim of an “image enhancer” such as myself is to improve these poor images, usually by digital means, such that they better resemble the true, “optical object,” input to the system. This problem is notoriously “ill-posed,” i.e. any direct approach at inversion of the image data suffers strongly from the presence of even a small amount of noise in the data. In fact, the fluctuations engendered in neighboring output values tend to be strongly negative-correlated, so that the output spatially oscillates up and down, with large amplitude, about the true object. What can be done about this situation? As we shall see, various concepts taken from statistical communication theory have proven to be of real use in attacking this problem. We offer below a brief summary of these concepts.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

SEM/EDS Characterization of Uncommon Metal Whiskers and Determination of Underlying Growth Mechanisms

2018 ◽  
Author(s):  
D. Basak ◽  
L. H. Ponce
Keyword(s):  
Reliability Analysis ◽  
Case Studies ◽  
Whisker Growth ◽  
Innovation Systems ◽  
Growth Mechanisms ◽  
Crystal Oscillator ◽  
Analysis Laboratory ◽  
Investigative Techniques

Abstract Two case-studies on uncommon metals whiskers, performed at the Reliability Analysis Laboratory (RAL) of Northrop Grumman Innovation Systems, are presented. The components analyzed are an Oven Controlled Crystal Oscillator (OCXO) and an Electromechanical Relay. Investigative techniques were used to determine the chemical and physical makeup of the metal whiskers and develop an understanding of the underlying effects and mechanisms that caused the conditions conducive to whisker growth.

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