SURFACE LAYER THICKNESS AND ANISOTROPY OF THE SURFACE ENERGY OF CUBIC RUTHENIUM CRYSTALS

В работе рассмотрены вопросы анизотропии поверхностного слоя и анизотропии поверхностной энергии кубических кристаллов рутения. В основе этого рассмотрения лежит эмпирическая модель атомарно-гладких кристаллов, толщина поверхностного слоя которых зависит от одного фундаментального параметра -атомного объема элемента. Расчеты кристаллов рутения показали, что толщина поверхностного слоя кристаллов рутения во всех направлениях не превышает d (I) < 10 нм и они представляют собой наноструктуру. Кристаллы рутенийалюминий, рутенийгафний, рутенийтитан, рутенийцирконий имеют ơ > 3 Дж/м в направлении (100) . Нами рассмотрена задача о диффузии газа в нанометровой пластине рутения. В отличие от классической задачи в полученном уравнении появляется логарифмический член. Это приводит к расходимости в начале координат. Поэтому граничные условия нужно задавать не при x = 0, а при x = d (0) - длине де Бройлевской волны электронов. Только в этом случае имеют смысл классические уравнения диффузии. Существенно также, что, согласно полученному уравнению, диффузии нанопластины зависит как от материала пластины через коэффициент диффузии массивного образца, так и от размерного фактора. В классическом случае такой зависимости нет. Для описания фазовых переходов в наноструктурах предложены различные модели, среди которых можно отметить метод среднего поля Ландау, в котором используется параметр порядка. Мы воспользуемся теорией Ландау, заменяя температуру T на координату h . The paper deals with the anisotropy of the surface layer and the anisotropy of the free surface energy of cubic ruthenium crystals. This consideration is based on an empirical model of atomically smooth crystals, the thickness of the surface layer of which depends on single fundamental parameter - the atomic volume of an element. Calculations of ruthenium crystals showed that the thickness of the surface layer of ruthenium crystals in all directions does not exceed d(I)< 10 nm and they represent a nanostructure. Crystals of ruthenium aluminum, ruthenium hafnium, ruthenium titanium, ruthenium zirconium have ơ > 3 J/m in the (100) direction. We have considered the problem of gas diffusion in a nanometer ruthenium plate. In contrast to the classical problem, a logarithmic term appears in the resulting equation. This leads to divergence at the origin. Therefore, the boundary conditions must be specified not at x = 0, but at x = d (0) - the de Broglie wavelength of electrons. Only in this case the classical diffusion equations are meaningful. It is also important that, according to the obtained equation, the diffusion of the nanoplate depends both on the material of the plate through the diffusion coefficient of the bulk sample and on the size factor. In the classical case, there is no such dependence. Various models have been proposed to describe phase transitions in nanostructures, among which we can mention the Landau mean field method, in which the order parameter is used. We will use Landau's theory, replacing the temperature T with the coordinate h.

Assessment of the effect of the steels structure dispersion on its magnetic and mechanical properties

Introduction: The control of the mechanical properties of structural steels is one of the main processes that regulate the service life of equipment. In most technical processes (pressure treatment, welding, rolling, thermal exposure), structure changes both in local areas and in the entire volume. Changes in the steel structure entail changes in its properties and as a result in local areas, at various stages of operation, the likelihood of the occurrence and development of critical defects increases. Its presence significantly affects the performance of the equipment, and leads to premature aging of the material and its failure. Precisely because the control of the mechanical properties of steel remains one of the urgent problems, new control methods are being developed. It is known that all properties of steel depend on the structure of the substance, however, studies on the effect of the dispersion of the structure under consideration on the mechanical properties are presented in an insignificant amount. Purpose: to analyze from a mathematical point of view the influence of the factor of different grain size, as a parameter reflecting the dispersity of the system, on the mechanical properties of structural steel. The paper studies a heat-treated planar samples of steels 15KhSND, 09G2S and St3. Methods of research: scanning electron and optical microscopes are used to study the grain structure and grain boundaries; SIAMS 700 software package is used for finding the boundaries and average data of the grain structure; portable X-ray fluorescence analyzer of metals and alloys X-MET 7000 is used to determine the chemical composition of the test samples in percentage; tensile testing machine IR-50 is used for measuring the tensile strength of samples; Vickers hardness tester is used to determine the hardness of samples. Results and discussion: it is found that there is a satisfactory correlation for the mechanical properties of structural steels (hardness and ultimate strength) and the grain size factor, which can be used to predict the hazardous states of structures and the operating time. The analysis of variance and regression of the detected dependencies is carried out. It is noted that the dropout of some values from the general regression dependence can most likely be associated with a decrease in the value of internal stresses as a result of a decrease in the distortions of the crystal lattice of steel occurring during heat treatment. It should be noted that the processes occurring and the degree of its influence on the properties of the structural steels under consideration can be different due to the presence of different amounts of alloying elements in the composition of the studied steels.

Thermodynamic properties of alloys binary In—Pr (Nd) and ternary In—Pr (Nd)—Ni systems

The thermochemical properties of In—Pr system melts in the range of compositions 0 < xIn < 0,4 and In—Nd in the whole concentration range at 1573 ± 1 K were investigated by isoperibolic calorimetry. The obtained data for the In—Pr system melts were extrapolated to the unexplored concentration interval, taking into account that at xPr = 1 the integral and partial mixing for Pr enthalpy are equal to zero. It was found that the first partial for Pr and the minimum enthalpy of mixing are equal to –139 ± 11 and –40,3 ± 0,2 kJ / mol, respectively. For the In—Nd system the first partial for In and Nd, the minimum enthalpy of mixing is equal to −131,7 ± 11, −140,6 ± 12 і –43,3  0,2 kJ / mol, respectively. Comparison of ΔHmin, melts of the five previously studied In—Ln systems from the ordinal number Ln (zLn) together with the data obtained in this work showed that they are described by a single trend line. For ΔHmin of melts of In—Eu (Yb) systems there are very insignificant deviations from the trend line. But for the size factor, these deviations from the trend line are more significant. The enthalpies of formation of some intermetallics of In—Ln systems are known, and most of them belong to the compound LnIn3. But there is no complete agreement between these data. The results of the most modern work show less dependence on the serial number of lanthanide and are more exothermic for heavy lanthanides, compared with other data. Keywords: thermochemical properties, compounds, melts, In, Pr, Nd.

Mutual Fund Performance Persistence and Competition: Pakistan’s Open Ended Mutual Fund Performance Analysis

Mutual Funds through its professional managers enable small investors to enjoy benefits of capital market with small amount. This study with special focus on Pakistani Mutual Fund industry, tests the suitability of traditional measures and multifactor, asset pricing models on the Mutual Fund performance. Owing to rareness of the applicability of the multifactor models in comparison to traditional measures, in evaluating Mutual Fund performance in modern day Pakistani research, the study uses CAPM, Fama French, Carhart models in the performance evaluation of Pakistan Mutual Fund. The data of 100 open-end Mutual Funds, for the period 2005 to 2017 was collected from Mutual Fund Association of Pakistan; while the risk free rates data was collected from State Bank of Pakistan and Stock data from Pakistan Stock Exchange for predicting the results, Ratio analysis, CAPM, Fama French-3 Factor and Carhart-4 factor model were used to understand its suitability. The results demonstrated that application of CAPM, affect market factors of majority of the portfolios.Where as in other two models (Fama French, Carhart) the majority of the portfolios are insignificantly affected by the size factor, value factor and Momentum factor. The Gibbon Rose Shanken unveils the suitability of the best model and justify CAPM as the better model among the three competing models in evaluate on theMutual Fund performance in Pakistan. The study has certain implications for the managers of assets management companies as well as useful for the investors in knowing which funds perform better and which kind of funds are ideal for investment.

Collision Avoidance Controller for Unmanned Surface Vehicle Based on Improved Cuckoo Search Algorithm

For the dynamic collision avoidance problem of an unmanned surface vehicle (USV), a dynamic collision avoidance control method based on an improved cuckoo search algorithm is proposed. The collision avoidance model for a USV and obstacles is established on the basis of the principle of the velocity obstacle method. Simultaneously, the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS) is incorporated in the collision avoidance process. For the improvement of the cuckoo algorithm, the adaptive variable step-size factor is designed to realize the adaptive adjustment of flight step-size, and a mutation and crossover strategy is introduced to enhance the population diversity and improve the global optimization ability. The improved cuckoo search algorithm is applied to the collision avoidance model to obtain an optimal collision avoidance strategy. According to the collision avoidance strategy, the desired evasion trajectory is obtained, and the tracking controller based on PID is used for the Lanxin USV. The experimental results show the feasibility and effectiveness of the proposed collision avoidance method, which provides a solution for the autonomous dynamic collision avoidance of USVs.

Effect of Cutting Size on the Performance of Exogenous Auxin IBA in Vegetative Propagation of Rubus erythroclados Mart. ex Hook. f.

Aim: The climbing shrub Rubus erythroclados Mart. ex Hook. f. (amora-verde) has great food (fruits) and medicinal (leaves) potential. However, this species remains understudied. The objective of this study was to evaluate the interaction between cutting size and IBA concentration in the vegetative propagation of R. erythroclados by stem cuttings. Study Design: The experimental design used was completely randomized in a 3x5 factorial combination. The cutting size factor was represented by three levels (10, 15 and 20 cm) and IBA concentration factor by five levels (0, 1,000, 2,000, 3,000 and 4,000 mg L-1). Results: There was an interaction between the factors in 13 of the 19 variables analyzed, being: live cuttings at 30 and 60 days, live cuttings with callus formation, sprouted cuttings at 30, 60 and 90 days, rooted cuttings, shoot number, shoot diameter, root number, root length, length of the largest root and root diameter. Size increase of the R. erythroclados cuttings caused a decrease in the phytotoxic effect of IBA in the development of the aerial part. The effect of IBA in response to rooting induction, in the larger size of R. erythroclados cuttings, required an increase in IBA concentration compared to the cuttings of shorter size. Conclusion: Cuttings of 10 and 15 cm treated with 1,000 mg L-1 of IBA showed greater rooting (20.0%) compared to the other treatments, being, therefore, indicated for the vegetative propagation of R. erythroclados by stem cuttings.

Does Five-Factor Model Perform Better Than Three Factor Model? Evidence from Developed Countries of The Asia Pacific Region

This study evaluates whether the “Fama-French five-factor model” can explain the variations in expected returns better than the “three-factor model.” Using the stock returns and accounting variable data from DataStream for 1,300 plus listed firms across six developed countries of the Asia Pacific region, including; Australia, Hong Kong, Japan, Israel, New Zealand, and Singapore for the period of Jun-2006 to February-2020. The paper is the first to examine the “five-factor model” performance across the developed countries of the Asia Pacific region. The empirical findings reveal that the Asia Pacific region for the sample period earns an equity premium. In addition, results report the redundancy of size factor (SMB) and value factor (HML), while the profitability (RMW) and investment premium (CMA) are positive and significant. Moreover, the study used Gibbons, Ross, and Shanken (GRS) test to the asset pricing model. The GRS test results on the “five-factor model” compared with the “three-factor model” demonstrate that profitability and investment factors add significant explanatory power to the analysis in the Asia Pacific region.

Expectations and Stock Market in Nepal

This study examines the presence of both rational and adaptive expectations hypotheses in the Nepalese stock market by employing panel data analysis under the Fama–French three-factor model. Under the adaptive expectation hypothesis, the book to market equity is an essential determinant in the Nepalese stock market, and only the past 2-year information can explain investment decisions. Likewise, under the rational expectation hypothesis, the value factor, size factor and excess market return are important determinants during the investment decision. The past 3 years of information and the next 3 years of future information are necessary to estimate stock market return under rational expectation. Thus, this study reveals that the investment decision in the Nepalese stock market depends on the investor’s choice and preference upon the factors that are incorporated in the Fama–French three-factor model and the types of expectations in which the investors mostly believe.

An Improved Cuckoo Search Algorithm for Multithreshold Image Segmentation

Image segmentation is an important part of image processing. For the disadvantages of image segmentation under multiple thresholds such as long time and poor quality, an improved cuckoo search (ICS) is proposed for multithreshold image segmentation strategy. Firstly, the image segmentation model based on the maximum entropy threshold is described, and secondly, the cuckoo algorithm is improved by using chaotic initialization population to improve the diversity of solutions, optimizing the step size factor to improve the possibility of obtaining the optimal solution, and using probability to reduce the complexity of the algorithm; finally, the maximum entropy threshold function in image segmentation is used as the individual fitness function of the cuckoo search algorithm for solving. The simulation experiments show that the algorithm has a good segmentation effect under four different thresholding conditions.