bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematics, computers in mathematics, and gender: public perceptions in context

Authors: Forgasz Helen J. , Leder Gilah C.
Published: December 2021

In Australia, national tests of mathematics achievement continue showing small but consistent gender differences in favor of boys. Societal views and pressures are among the factors invoked to explain such subtle but persistent differences. In this paper we focus directly on the beliefs of the general public about students’ learning of mathematics and the role played by computers, and then we compare the findings with data previously gathered from students. Although many considered it inappropriate to differentiate between boys and girls, gender based stereotyping was still evident. Matemáticas, ordenadores en matemáticas y género: percepciones públicas en contexto En Australia, los test nacionales del logro matemático continúan mostrando pequeñas pero consistentes diferencias de género en favor de los chicos. Las presiones y visiones sociales están entre los factores invocados para explicar tales diferencias sutiles pero persistentes. En este trabajo nos centramos directamente en las creencias del público en general acerca del aprendizaje matemático de los estudiantes y del papel desempeñado por los ordenadores, y después comparamos las conclusiones con datos previamente obtenidos de los estudiantes. Aunque muchos consideran inapropiado diferenciar entre niños y niñas, todavía son evidentes estereotipos basados en el género.Handle: http://hdl.handle.net/10481/16012
Conocimiento del profesor en la interpretación de errores de los alumnos en álgebra

Authors: Huitrado José L. , Climent Nuria
Published: December 2021

En este trabajo se exponen los resultados parciales de una investigación sobre el conocimiento profesional de los profesores evaluadores de olimpiadas matemáticas puesto en acción al analizar errores relativos al álgebra. A través de dos pruebas de interpretación de errores, y a partir de un análisis inspirado en la teoría emergente de los datos, obtuvimos dimensiones para la caracterización de saberes en la comprensión de los errores. En los resultados describimos los saberes de un profesor estrechamente relacionados con la práctica y con el conocimiento sobre el aprendizaje de los alumnos.Teacher’s knowledge in the interpretation of student’s errors on algebraThis paper presents the partial results of a research on the professional knowledge of mathematics olympiad evaluators teachers put into action when analyzing errors relating to algebra. By means of two tests on errors interpretation and by using analysis inspired by the grounded theory, we obtained dimensions for the characterization of knowledge in understanding about errors. In the results section, we describe a teacher's knowledge related to practice and knowledge about students’ learning.Handle: http://hdl.handle.net/10481/29577Nº de citas en WOS (2017): 1 (Citas de 2º orden, 0)Nº de citas en SCOPUS (2017): 1 (Citas de 2º orden, 0)
Different possibilities to learn from the same task

Authors: Kullberg Angelika , Runesson Ulla , Mårtensson Pernilla
Published: December 2021

In this paper we focus on variation of the design and the implementation of a specific task during three mathematics lessons in the 8th grade in a learning study (Marton & Tsui, 2004; Runesson, 2008). The theme of the lesson was division, with a denominator between 0 and 1. The teachers wanted their students to understand that when dividing with a denominator less than 1, the quotient is larger than the numerator. Four teachers collaboratively planned, analyzed and revised three lessons in a cyclic process. The study shows that the implementation of the task changed between the lessons. Although the same task was used in the lessons, the way it was enacted provided different possibilities to learn.Diferentes posibilidades para aprender con una misma tareaEn este artículo nos centramos en la variación del diseño y la implementación de una tarea específica durante tres sesiones de clase de matemáticas en octavo grado en un estudio de aprendizaje (Marton y Tsui, 2004; Runesson, 2008). El tema de las clases fue la división con un divisor entre 0 y 1. Los profesores querían que sus estudiantes entendieran que, cuando se divide por un divisor menor que 1, el cociente es mayor que el numerador. Cuatro profesores colaboraron, en un proceso cíclico, en la planificación, análisis y revisión de las tres sesiones de clase. El estudio muestra que la implementación de la tarea cambió entre las sesiones. A pesar de utilizarse la misma tarea en las sesiones, la manera en que se implementó proporcionó diferentes posibilidades para aprender.Handle: http://hdl.handle.net/10481/31597Nº de citas en WOS (2017): 4 (Citas de 2º orden, 2)Nº de citas en SCOPUS (2017): 4 (Citas de 2º orden, 2)
Análisis del aprendizaje de geometría espacial en un entorno de geometría dinámica 3-dimensional

Authors: Gutiérrez Ángel , Jaime Adela
Published: December 2021

El creciente uso de software de geometría dinámica 3-dimensional plantea nuevas cuestiones a los investigadores en Educación Matemática. Para aportar información sobre el aprendizaje de geometría espacial en esta disciplina mediante entornos de geometría dinámica 3-dimensional, y sobre posibles fortalezas y debilidades de tales entornos, presentamos resultados de una investigación experimental en la que se analiza cómo un estudiante de altas capacidades matemáticas aprende conceptos relativos a paralelismo entre rectas y/o planos en el espacio mediante la resolución de actividades en un entorno de Cabri 3D.Analysis of space geometry learning in a 3-dimensional dynamic geometry environmentThe increasing use of 3-dimensional dynamic geometry software raises new questions to researchers in mathematics education. To contribute information about the learning of space geometry in Secondary School based on 3-dimensional dynamic geometry software environments, and about possible strengths and weaknesses of such environments, we present results from a teaching experiment designed to analyze a gifted student’s learning of concepts relative to parallelism between straight lines and/or planes in the space based on solving activities in a Cabri 3D environment.Handle: http://hdl.handle.net/10481/34155WOS-ESCINº de citas en WOS (2017): 1 (Citas de 2º orden, 0)Nº de citas en SCOPUS (2017): 1 (Citas de 2º orden, 0)
Clinical and Immunological Outcomes of Extracorporeal Shock Wave Therapy in Chronic Prostatitis/Chronic Pelvic Pain Syndrome
Authors: Gorpynchenko Ihor , Nurimanov Kamil , Nedogonova Olena , Poroshina Tetiana , Savchenko Viktoriia , Sherban Mariia , Drannik Heorhii
Published: December 2021

Extracorporeal shock wave therapy (ESWT) is a non-pharmacological, non-invasive procedure   for the treatment of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS).
The objective: to evaluate the dynamics and relationship of clinical symptoms and ejaculate cytokine concentrations during the use of ESWT in the treatment of patients with CP/CPPS.
Materials and methods. The study included 37 patients aged 18–45 years with CP/CPPS who received ESWT in the projection of the prostate and seminal vesicles. Symptoms of prostatitis were assessed by the NIH-CPSI scale, and ejaculate cytokines were assessed by ELISA before and after treatment. To analyze the results of treatment, patients with a significant reduction in the activity of prostatitis symptoms (by 6 or more points on the NIH-CPSI scale) were grouped into subgroup A. Patients with insufficient efficacy were grouped into subgroup B.
Results. After treatment, 21 (57%) patients significantly reduced the intensity of prostatitis symptoms (subgroup A). Patients with insufficient efficacy were grouped into subgroup B. The content of proinflammatory cytokine – interleukin-1β ejaculate significantly (p<0.05) increased only in these patients. In subgroup A, a significant correlation was found between the assessment of prostatitis symptoms on the NIH-CPSI scale and the concentration of interleukin-1β ejaculate (Spearman’s r=0.650; p<0.001 and r=0.735; p<0.001 before and after treatment, respectively). The concentration of the anti-inflammatory cytokine ejaculate (interleukin-10) increased significantly only in subgroup A (p<0.05).
Conclusion. Extracorporeal shock wave therapy provides a significant reduction in the symptoms of prostatitis causing dosed minimal damage and inflammation of the prostate and seminal vesicles, associated with an increase in the level of interleukin-1β in the ejaculate.
Peculiarities of Sexual Health of Women of Reproductive Age Depending on the Types of Localization of Paraurethral Glands
Authors: Kosyuhno Maryna
Published: December 2021

Sexual health is a state of physical, emotional, mental and social well-being associated with sexuality. The complexity of the female sexual reaction lies in its dependence on many physiological, psychological and sociocultural factors.
The objective: a comprehensive analysis of erogenous zones in women of reproductive age, taking into account the types of localization of the paraurethral glands, assessment of their sexual function and the causes of its disorders.
Materials and methods. A comprehensive study to confirm the existence of female paraurethral glands and their functional activity, performed at the Institute of Urology of the National Academy of Medical Sciences of Ukraine (Department of Reconstructive Urology and Advanced Technologies), took 94 relatively healthy women of reproductive age, who as a result of a comprehensive examination paraurethral glands of different types of localization (anterior, posterior, diffuse). Analytical-synthetic, comparative analyzes were used. Average values with their standard error were calculated; in cases of comparison of statistical values, Student’s test was used.
Results. The relationship between the localization of the paraurethral glands in women of reproductive age and the peculiarity of the manifestation of sexual relations has been traced. Differences in the number and severity of the reaction of erogenous zones among this category were revealed. Sexual dysfunctions in 24 (25.5%) of 94 women were predominantly in the posterior type of localization of the glands (50% versus 37.5% and 12.5% in the anterior and diffuse types, respectively). Among the reasons for dissatisfaction with sexual relations, women most often indicated satisfaction (36.2%), then – reaching orgasm (22.4%) every fifth noted the absence (decrease) of sexual arousal and 13.7% – a decrease in desire; dyspareunia was observed in 8.6% of cases, was inconsistent and manifested itself with individual partners. These features were mostly manifested in cases with the posterior type of localization of the paraurethral glands of different reproductive ages.
Conclusion. The results obtained made it possible to reveal the features of the sexual life in women, depending on the type of localization of their paraurethral glands.
Phylogenetic analysis shows that New Zealand isolates of Neonectria ditissima are similar to European isolates
Authors: Everett Kerry R. , Pushparajah Irene P.S. , Scheper Reiny W.A.
Published: December 2021

Neonectria ditissima causes a debilitating apple tree canker disease. We determined the efficacy of polymerase chain reaction primers, originally designed for European strains, by sequencing New Zealand strains. The concatenated ribosomal inter-transcribed spacer and β-tubulin gene regions of 17 New Zealand isolates were compared with those of two European strains by phylogenetic analysis. New Zealand and European isolates of N. ditissima were in the same clade, suggesting that there has been little change in these gene regions following introduction to New Zealand. There was 100% homology with Bt-FW135 and Bt-RW284 primers. Based on sequencing 17 New Zealand isolates from several locations, these polymerase chain reaction primers can be relied upon to amplify New Zealand isolates of N. ditissima.
Stunting prevalence and its associated factors among children in primary school in Sidoarjo District: A secondary data analysis
Authors: Sholihah Lini Anisfatus
Published: December 2021

Stunting is one under-nutrition condition that might be caused by inadequate nutrition consumption or frequent infection. Stunting prevalence in primary school-age children (PSAC) is still high in the third world and Indonesia. This present paper aimed to study the prevalence and the associated factors such as sex, school-area, and food intakes of stunting in PSAC in Sidoarjo, 2018. This study is cross-sectional research using secondary data from baseline data of emotional demonstration projects in primary school students. Two hundred students were recruited from four schools representing urban and rural areas in Sidoarjo. Food intake was interviewed using SQ-FFQ. Children height was measured using microtoice. HAZ-score was calculated using WHO Anthro Plus software. Student t-test was done to test any differences in stunting prevalence between sex and school areas. The Chi-square test was used to check the difference in proportion for categories. Our results suggested the stunting prevalence among PSAC in Sidoarjo was 18% and was significantly greater in the rural area (p= 0,010). School location has association with stunting (OR= 2,7; 95%CI 1,25-5,8). In conclusion, we did not find any significant difference in food intakes, although stunted children were more likely to consume energy and carbohydrate. This condition must be considered to prevent obesity in stunted children
Formulasi food bar berbasis pangan lokal tinggi asam amino esensial untuk anak balita stunting
Authors: Darawati Made , Yunianto Andi Eka , Doloksaribu Tetty Herta , Chandradewi AASP.
Published: December 2021

Local food can be used as an alternative to additional food for toddlers, namely food bars. The study was conducted in June-November 2017. The design of this research was experimental using a completely randomized design (CRD). The food bar formulation was mixed with 20g and 25g tuna, while 20g and 25g mackerel fish. Organoleptic test data were analyzed using ANOVA. Proximate analysis of food bars using the AOAC method. Food bars' essential amino acid content was carried out using LCMS and total microbial analysis using the ALT method. Food bar analysis selected from the test results by semi-trained panelists and consumer panelists is f4 with 25g tuna mixing with indicators of color (p= 0,000), aroma (p= 0,003), taste (p= 0,040), and texture (p= 0,167). Food bar in 100 grams contains: energy 470,77 kcal, 15,65% protein, 24,13% fat, 47,74% carbohydrates, 2.14% ash, and 10.33% water. The results of the total microbial test on the food bar showed a value of 4,5 x 102 cfu/g and an Aw value of 0,86. Food bar formula F4 is a formula selected by panellists that contain ten high essential amino acids
WHAT DRIVES CITY BRAND ATTRACTIVENESS? AN EMPIRICAL STUDY ON SOME PROVINCES IN INDONESIA
Authors:   University of HKBP Nommensen, Faculty of Economics and Business, North Sumatera, Indonesia, SILABAN Pasaman
Published: December 2021

Current study is aiming to investigate the key determinant factors of city attractiveness. Research background was triggered by, firstly, the lack of literature focused on this phenomenon. Secondly, the concern of people to live in environmentally friendly place and the local plan to complete city management in order to increase economics performance and international competitiveness by using visibilities and economics benefit globally. This research took sampling with specific target (600 respondents) from local potential talents, such as young entrepreneurship, international business, high educated persons with age range 25 until 45 years old. A ten likert scale is used to evaluate city brand which is considered as a key factor to influence city attractiveness. A structural equation modeling is deployed to analyze the city attractiveness driven. Those driven factors such as environmental outlook, responsive social service, tourism and cultural tangible, education and job opportunity, safety and health, international level and city attractiveness performance. Statistical outputs demonstrated that all hypotheses (H1 until H5) have shown significant antecedents of city attractiveness. H6 stated that international level is insignificant as a driver for city attractiveness performance.
Новый сорт гороха посевного Триумф Сибири
Authors: Омельянюк Людмила Валентиновна , Асанов Акимбек Мырзаевич , Пахотина Ирина Владимировна , Кармазина Алена Юрьевна
Published: December 2021

Оценены 5 сортов гороха сибирской селекции усатого морфотипа с неосыпающимися семенами по урожайности и качеству зерна, адаптивности и комбинационной способности, а также 20 диаллельных гибридов F1, созданных с использованием этих сортов. Исследования проведены в 2016 – 2020 гг. в зоне южной лесостепи Западной Сибири. Новый сорт Триумф Сибири, включенный в Госреестр РФ в 2021 г. по 10 и 11 регионам, получен методом индивидуального отбора из гибридной комбинации (Эрби × Демос), разновидность — cirrosum-ecaducum. Этот сорт является ценным для селекции донором признаков технологичности гороха — усатого листа и неосыпаемости семян. Сорт Триумф Сибири можно использовать в селекционных программах для ограничения длины стебля гороха и одновременно повышения продуктивности растений. В конкурсном сортоиспытании он ежегодно, за исключением самого засушливого 2020 г. (ГТК 0,60), был достоверно урожайнее длинностебельного стандарта Омский 9. В среднем за 2016 – 2020 гг. урожайность сорта (4,19 т/га) превысила урожайность стандарта на 0,45 т/га. Максимальная урожайность получена в 2019 г. (ГТК 0,99) — 5,64 т/га (+0,57 т/га) при повышенной устойчивости к полеганию. Сорт отзывчив на улучшение условий выращивания — bi = 1,11, но отличается нестабильностью — = 0,35. Содержание белка находится на уровне стандарта — от 22,0 до 25,4 %.
Цитогенетические особенности родиолы розовой при выращивании в Нечерноземной зоне России
Authors: Саматадзе Татьяна Егоровна , Савченко Ольга Михайловна
Published: December 2021

Цитогенетический анализ показал, что мейоз родиолы розовой проходит по классическому типу. Различия качества семян и их урожайности в зависимости от условий года наблюдения могут свидетельствовать о необходимости проведения мероприятий по адаптации растений к неблагоприятным факторам среды. Крупные семена независимо от условий года сбора отличались высокой всхожестью и энергией прорастания. Выявлены особенности мейоза у этого вида (асинхронности развития в пределах 1 микроспорангия и микроспороцита). Повышенное число клеток с нарушениями в мейозе у растений, выращенных в неблагоприятных климатических условиях, особенно в период созревания семян, вероятно, обусловлены их реакцией на стрессовые условия их произрастания, что может приводить к снижению жизнеспособности пыльцы, а в дальнейшем и к снижению урожайности семян.
Мониторинг аллелофонда EAB-локуса групп крови в процессе селекции крупного рогатого скота голштинской породы в условиях Сахалинской области
Authors: Шукюрова Елена Борисовна , Марзанов Н. С.
Published: December 2021

В селекции крупного рогатого скота (КРС) большое значение имеет изучение концентрации аллелей групп крови и динамики частоты встречаемости для выявления изменений в генетической структуре, происходящих в процессе селекции, как породы в целом, так и отдельного стада. Установлены изменения генетической ситуации в стаде КРС голштинской породы в условиях Сахалинской области. Генетическую ситуацию контролировали с помощью EAB-локуса групп крови у 782 животных, рожденных в 1999 – 2018 гг. Анализ динамики аллелофонда во времени показал сокращение общего числа аллелей, участвующих в формировании генотипов EAB-локуса, с 42 (потомки 1999 – 2000 гг. рождения) до 21 – 23 (потомки 2015 – 2018 гг. рождения). Произошло изменение уровня гомозиготности в сторону его увеличения с 8,4 (потомки 1999 – 2000 гг. рождения) до 18,2 (потомки 2017 – 2018 гг. рождения), и, как следствие этого, наблюдалось уменьшение числа эффективных аллелей. Использование большого числа быков, носителей аллели G2Y2E2’Q’, привело в хозяйстве к увеличению рождения потомков (2017 – 2018 гг.), носителей данной аллели, в 1,7 раза. У потомков, рожденных с 2003 по 2010 г., элиминировали аллели Q, B2B’’, B2G2KI1O1D’O’Q’, O1Y2, I’, I2I’, O1Y2D’G’Q’, G3O1T1A2’E3’K’, I1O1Y2, QQ’, Y2Q’ и др. За весь период исследования генофонд восполнился только 25 аллелями, что привело к снижению генетического разнообразия в стаде.
Increasing wear resistance of the protective sleeve of the centrifugal pump made of gray cast iron by surface hardening
Authors: Lalazarova Nataliia , Afanasieva Оlga , Popova Olena , Dmytrenko Oleksiy
Published: December 2021

One of the weak spots that reduce the guaranteed operating time of centrifugal pumps is the assembly that includes the seal and protective sleeves. The main purpose of the bushings in the rotor kit is to protect the shaft from corrosion, erosion and wear. The sleeve operates under abrasive wear conditions by packing elements and abrasive particles that get into the liquid pumped by the pump. The protective sleeves made of gray cast iron do not meet the service life in connection with accelerated surface wear. Goal. The purpose of the work is to ensure high wear resistance of cast iron pump parts by heat treatment. Method. The chemical composition was determined on a portable laser analyzer Laser Z200 C +. The structure was studied using an optical microscope. The wear was investigated by the roller-block method on a friction machine. Surface quenching was carried out with a high-frequency lamp generator in a single-turn inductor. Results. The microstructure of gray cast iron as cast consists of pearlite, ferite, double phosphide eutectic and inclusions of lamellar graphite. Microhardness of small-lamellar pearlite is Н50 = 1550–2220 MPa, microhardness of phosphide eutectic is Н50 = 6500–8000 MPa. Surface induction quenching by high-frequency currents followed by low tempering is an effective way to increase the wear resistance of cast iron products of small cross-section and does not cause warping. Cast iron for surface quenching should have a pearlite structure, and graphite should be contained in the form of small inclusions. The optimal heating temperature for induction hardening was determined as 900 °С, which made it possible to obtain the microstructure of the hardened layer – martensite, double phosphide eutectic and graphite. Scientific novelty. The developed modes of surface quenching make it possible to preserve a double phosphide eutectic in the structure of the surface layer, which makes it possible to obtain high hardness and wear resistance of the hardened layer. Practical significance. Surface induction quenching with low tempering of cast gray iron increased its wear resistance by 2,4 times. The previous normalization had practically no effect on the durability of cast iron, since its structure contains less than 10% ferrite.
Studying phase formation of 12Х18Н10Т alloy and copper after friction welding
Authors: Sanin Anatoly , Mamchur Igor , Mamchur Stella , Nosova Tetyana
Published: December 2021

The technology of joining alloy 12X18H10T and copper has been studied. The use of friction welding is proposed.  Modern development of technology requires the use of new technologies and materials. Despite the increase in the use of composite materials, and especially on the basis of the polymer matrix, metal alloys remain indispensable. Due to their physical and mechanical properties, metal-based alloys are used in rocket and space technology, mechanical engineering, and other industries. Goal. The aim of this work is the reason for the decrease in the mechanical properties of the connection 12Х18Н10Т – М1, which were obtained under suboptimal conditions. Friction welding was developed in early 1956 in the USSR. Since the 1960s, other countries have also begun to develop friction welding. This tool is a type of pressure welding, during which the metal is heated by friction of one of the parts of the product. At the end of the process, the final connection takes place. This type of welding is used in aircraft construction, rocketry, machine building, etc. In Ukraine, research in this direction is conducted at the Eugene Paton Institute of Electric Welding. The parameters of the friction welding technological process are considered. Results. The samples of welded joints 12Kh18N10T + M1 were studied. The following methods were used: mechanical tests; metallographic and electro-microscopic studies; hardness measurements; micro-X-ray spectral study. Originality. Welding joints with low strength were investigated; they were obtained for the following parameters: relative rotation speed 0.4 m/s, pressure during heating 80 MPa, pressure during forging 80 MPa, upset value 9 * 10-3 m samples with low strength varied in the deformed layer of steel from the joint surface to the base metal from 3240 MPa to 2450 MPa; in a deformed copper layer from 1020 MPa to 690 MPa. On samples that had high strength, the microhardness varied on the steel side from 2260 MPa in the contact surface to 2160 MPa, and in copper from 590 MPa to 460 MPa. Fig. 1 shows the microstructure of the deformed zones of the welded joint 12X18H10T, obtained according to the optimal parameters. Practical value. The reason for the decrease in the mechanical properties of the 12Х18Н10Т – М1 joint was established.
Effect of structure and phase content on wear resistance of the economical alloyed metastable and secondary hardening steels of Cr-Mn-Ti system
Authors: Bagrov Valeriy
Published: December 2021

Despite a large number of studies in the field of assessing the causes of the formation of hot and cold cracks during surfacing of wear-resistant alloys, today the issues of working out the use of economically alloyed wear-resistant materials and the technique of their surfacing remain relevant. Goal: The purpose of this work is to study the effect of the structure and phase composition on the wear resistance of economically alloyed metastable and secondary hardening steels of the Cr-Mn-Ti system, as well as with additional alloying with Mo, B, V. Mechanized surfacing was carried out with flux cored wires AN-22 and AN-20 with the supply of a de-energized additive to the head of the weld pool, which reduces the content of sulfur and phosphorus, the specific consumption of electricity and increases the assimilation of alloying elements and the relative mass of the flux. Cladding by manual arc welding was carried out with coated electrodes with the addition of a depleted CaF2-coated flux-cored wire filler. When surfacing with a de-energized additive, the ratio of the filler to the main electrode, the relative mass was determined by β = m1 / m2 (m1, m2 are the mass of the filler and the electrode rod, respectively). Submerged arc surfacing was carried out in the following modes: IN = 300 ... 350 A, UD = 26 ... 30 V, q = 6 ... 10 kJ / cm, with manual surfacing - IN = 180 ... 220 A, UD = 25 ... Results: The studies carried out confirm the possibility of the formation of a “white band” both in alloys with a high concentration of austenitizing elements (Mn, C, Ni) and when alloying carbide-forming elements with a relatively low affinity for carbon (V, Mo). The indicators of resistance to cracking (КС, j-integral, δС), and, consequently, resistance to wear of secondary hardening steels are higher than those of metastable and tool steels.
Research of surface layer properties of piston rings after gas thermal spraying
Authors: Hlushkova Diana , Bagrov Valeriy
Published: December 2021

Today, one of the important problems of mechanical engineering is to increase the reliability and durability of machines. A special place in this matter is occupied by increasing the wear resistance of parts. As for diesel construction, the problem of increasing the hardness and wear resistance of piston rings is very important. Goal. The goal is study of the structure and nature of changes in the hardness of the surface layer obtained by gas-thermal combined spraying, after grinding, running-in and mileage of the diesel engine, i. e., at all stages of the production cycle. Methodology. The coating on the rings was applied by the method of two-wire metallization with independent supply of wires made of 11X18M steel and molybdenum. Metallographic analysis was used to study the structure of the obtained coating. The condition of the surface layer after coating, grinding, running-in and diesel run was studied by measuring the microhardness. Results. Metallographic analysis of the interface between steel and molybdenum coating – cast iron for many rings and different parts of one ring shows that the coating interacts closely with the substrate along the entire application profile. The structure of molybdenum particles demonstrates their fineness. This is due to the fact that the rapid crystallization under pressure contributes to the creation of a fine-grained structure. Comparison of the microhardness of molybdenum and steel wires with steel-molybdenum coating indicates a significant strengthening of molybdenum and steel particles during spraying, due to the processes of structure formation. Experimental data indicate the stability of the hardness of both molybdenum particles and steel particles, which is important for the coating in operation. Originality. Features of formation of a gas-thermal covering at a simultaneous electric arc spraying of molybdenum and 11Х18М steel on piston rings from pig-iron are established. It is shown that a layered structure is formed, which consists mainly of steel and molybdenum particles. The reasons for the wide range of properties of steel and molybdenum particles have been clarified. It is proved that the operational properties of steel-molybdenum coating are due to its antifriction properties, porosity, which provides self-lubrication of the friction surface, good adhesion to the substrate, which increases by 3–4 times compared to traditional methods. Practical value. The proposed technology of gas-thermal spraying significantly increases the service life of piston rings operating in wear conditions.
Improving the technological process of increas-ing the durability of the working tool of hydrau-lic hammers by detonation spraying
Authors: Hlushkova Diana , Bagrov Valeriy
Published: December 2021

The development of modern technology places increasing demands on the performance of the hydraulic hammer parts. In a complex of problems of increasing their reliability and durability the question of wear resistance occupies a special place. Insufficient wear resistance limits the productivity of hydraulic hammers and their service life, increases the cost of repair and purchase of spare parts. Goal. The purpose of this work is to scientifically substantiate and experimentally confirm the effectiveness of strengthening the critical parts of the hydraulic hammer by detonation spraying. Methodology. Detonation spraying with hard alloy powder VK 25 (80 %) and the binder material PT-NA-01 (Ni 91 %, Al 9%) was performed on a cleaned surface without pre-treatment. VK 25 powder is a tungsten-cobalt carbide (WC-Co) containing up to 25% cobalt, and is used for work in conditions of fretting corrosion, abrasive wear at normal and elevated (up to 650 ° C) temperatures. A granular powder of 20 – 100 μm was used, which was melted in an oxygen-acetylene flame and gas flow and was transferred to the surface of the part. The thickness of the sprayed layer was 0.1 mm. The surface roughness of the parts before spraying was Ra 0.35–2.5. As a result of spraying, the roughness of the working surfaces of the parts increased to the values of Ra 4.8–5.4. Results. The composition of the coating based on tungsten carbide was chosen to strengthen the surface of the investigated parts by detonation spraying. Detonation spraying modes were selected. The conditions for hardening treatment were determined. The nature of damage to parts after detonation spraying was established. Originality To solve the problem of improving the performance of the working tool of hydraulic hammers, the use of the detonation method of coating was proposed. Practical value. The test results of the details strengthened by detonation spraying showed that the increase of wear resistance by 1,8 times in comparison with an initial variant was reached.
Increasing the corrosion resistance of turbine
Authors: Hlushkova Diana , Bagrov Valeriy , Hrinchenko Elena , Stepaniyk Andrey , Hnatiyk Anastasiya , Kalinina Nataliya
Published: December 2021

The reliability of the vane apparatus of steam turbines largely determines the operation of the turbine as a whole. The results of scientific research indicate that the surface operation of the blades in the wet - steam flow is caused by a combination of corrosion and drip erosion. The presence of chemical elements and compounds in the working fluid intensifies the process of blade wear. The pH value of the working environment, which can fluctuate significantly during operation, has a significant effect on the wear characteristics. The influence of methods of strengthening the leading edges of steam turbine blades made of steel is analyzed 15Х11МФ on corrosion resistance. Corrosion tests of blade samples were carried out, the inlet edges of which were strengthened in three ways: high current amplification, electrospark alloying with T15K6 alloy, electrospark alloying with steel 15Х11МФ According to the results of the tests, the layer strengthened by hardening by high-frequency currents has the lowest corrosion rate, the layer strengthened by electrospark alloying with T15K6 hard alloy has the highest. The corrosion rate of the layer reinforced by electrospark alloying of steel 15H11MF is 2.1 less than that of the layer reinforced with T15K6 alloy.
Modernization of the construction of the crane traveling wheel
Authors: Fidrovska Nаtalya , Slepuzhnikov Evgen , Chernyshenko Alexsandr , Perevoznyk Igor
Published: December 2021

The article discusses the modernization of the running wheel due to the introduction of an elastic element. The structure, which consists of three layers, the outer ones of which consist of strong steel material, and the middle layer consists of low-strength lightweight aggregate, which can significantly reduce dynamic forces, vibrations and shocks, which increases the reliability of cargo transportation. Calculations have shown that the stress state of a wheel with an elastic insert is less than that of an old-design travel wheel. The decrease in force and elastic factors in the travel wheel, which has an elastic insert, is explained by the fact that the use of an elastic ring leads to an increase in the bending stiffness of the outer ring of the shell. The obtained solution to the problem of the strength of a three-layer structure makes it possible to determine the stresses in the shell depending not only on its geometric parameters, but also on the shear modulus of the filler, which improves the reliability of the design and operation of such structures. Theoretical studies of the stress state of a three-layer cylindrical structure, taking into account the shear energy of the filler, makes it possible to assess the strength of such a structure and give certain recommendations for its use. Experimental studies that were carried out on an operating overhead crane fully confirmed a very significant reduction in oscillatory processes in travel wheels. The level of vibration acceleration in the vertical direction on the modernized drive wheel is almost 3 times less than the level of vibration acceleration on the drive wheel at idle speed of a conventional design.
Features of the construction and justification of the main parameters of the walking movement mechanism technological machines
Authors: Fidrovska Nаtalya , Yarizhko Alexsandr , Krupko Igor
Published: December 2021

The peculiarities of the design and process of movement of technological machines equipped with a four-axle stepping motor with the method of determining the main parameters of such a mechanism are considered. The factors influencing the operation of the drive of such a mechanism, their impact on efficiency and the main ways to improve such a mechanism of movement are shown.
Analysis of the characteristics of axial-piston hydraulic machines for drives for maintenance of airfields and planes
Authors: Avrunin Grygoriy , Shevchenko Valery , Shevchenko Dmitriy , Shcherbak Oleg , Pimonov Igor , Moroz Irina
Published: December 2021

Is an integral part of the development of the concept of forming a standard range of transport and technological hydrophilic modular means for maintenance of airfields and aircraft. Goal. Development of scientifically sound recommendations for determining the rational parameters of the hydraulic system with automation of control and energy saving during operation of modular vehicles for maintenance of airfields and aircraft, taking into account the potential of domestic engineering and critical imports of units. Methodology. Analysis of the development of axial-piston pumps and  motors according to the manufacturers' catalogs taking into account the needs of modular vehicles for maintenance of airfields and aircraft, in particular, taking into account the creation of modern hydraulic machines by  enterprise «Hydrosila»  by increasing pressure, speed and development new  regulators. Results. It is established that the domestic nomenclature of modern pumps and  motors of axial piston type allows to create three-dimensional hydraulic drives with power to 110 kW for transmissions with machine stepless remote electrohydraulic regulation of speed of rotation of wheels of modular vehicles and to  85 kW throttle drives of technological equipment with energy saving systems by using pumps with automatic regulators of change of working volume. It has been established that in the pumps for  of transmissions the ratio of mass to power is reduced three times.Originality.  Graphic dependences of power, supply and torque of standard size series on the working volume of axial-piston pumps and hydraulic motors of the domestic enterprise "Hydrosila" for volumetric hydraulic transmissions and technological equipment of aerodrome and aircraft maintenance facilities are constructed. Practical value. The possibility of a rational selection of axial-piston domestic hydraulic machines for the development of hydraulic drives for airfields and aircraft.
Analysis of energy losses in electric transmis-sion taking into account the Sommerfeld – Kononenko effect
Authors: Podrigalo Mihael Abovich , Podrigalo Nadegda Mihaelovna , Serikov Georgy Sergeevich , Serikova Irina Alekseevna
Published: December 2021

The use of an electric drive in modern vehicles allows solving a number of problems related to the issues of environmental and energy security of the country. However, this approach imposes a number of practical limitations. Among them there is such a significant factor as the limitation on the stored energy in the traction batteries and, as a consequence, the limitation of the mileage on one charge. One of the ways to solve this problem is to reduce mechanical losses associated with the appearance of resonance phenomena in rotating transmission elements and having an unbalanced mass. Goal. The goal is to assess the influence of the Sommerfeld – Kononenko effect on energy indicators during the transfer of rotation from the electric motor to the drive wheel of an electric vehicle.

To achieve this goal, it is necessary to determine the law of motion of the rotor of an electric motor and a car wheel using the energy approach and a model of complex motion. Methodology. To solve the problem of determining the law of rotation of an electric motor rotor, a dynamic model of an eccentric vibrator is adopted. The study takes into account the fluctuations in the angular velocity of the shaft with Hooke's hinge when the shaft axis deviates from horizontal positions. It is proposed to apply an energy approach using a model of complex motion to determine the law of rotation of an electric motor rotor and a wheel. Results. The dependence of the speed of rotation of the wheel of an electric vehicle is determined in accordance with the dynamic model under the conditions of fluctuations in the angular speed of transmission elements with Hooke's hinge when the wheel axis deviates from the horizontal position. Practical value. An energy approach is proposed for finding losses in a complex motion model to determine the law of rotation of an electric motor rotor and a wheel.

An analytical dependence of additional energy losses caused by wheel unbalance on vehicle mileage and wheel unbalance is found.
A model intended to choose optimal wooden construction software according to many criteria
Authors: Fil Nataliya , Kononykhin Aleksandr
Published: December 2021

Environmental friendliness gains increasing importance for people in constructing modern residential buildings. Wood is a natural polymer with unique properties that make it an excellent choice for the construction of environmentally-friendly new housing. New building technologies have significantly improved the performance of wood as a material. Modern software allows not only to get a 3D-visualization of the project, but to make the house strong and safe, save costs on construction, and reduce the build time of wooden houses. Currently, there are a large number of various software packages for wooden construction, so it may be a problem to choose the appropriate one based on the criteria of the required functionality and cost-effectiveness. Aim. This work aims at the development of a model intended to choose optimal wooden construction software according to many criteria, which will reduce the time of the scientifically grounded decision, and in such a way, increase the efficiency of a wooden house designing process. To achieve this goal, it is necessary to analyze the existing wooden construction software, to consider the criteria for selecting designing programs, to develop a model for scientifically grounded choice of software on many functional and cost criteria in the conditions of fuzzy information; and to provide an example of using this model has been developed. Methodology. A fuzzy multicriteria analysis of variants according to the Bellman-Zade scheme is used. Results. Modern building information technologies have expanded the possibilities of spatial planning of residential, working, shopping, entertainment, sports, and other areas of design. The model for the choice of wooden construction software that allows choosing software according to many functional and cost criteria in the conditions of fuzzy input information is presented. An example of using the developed model for the choice of wooden construction software is given. Practical value. The use of the developed model for wooden construction choice in the conditions of fuzzy information based on many functional and cost criteria will make the choice scientifically grounded.
Strip on elastic foundation described by different models, loaded by evenly distributed load
Authors: Kozhushko Vitaly , Krasnov Sergei
Published: December 2021

The problem of changing the size of the reactive pressures perceived by a strip at use of various models of the soil foundation and at various indicators of flexibility of the “strip-soil” system is investigated. The aim of the work is to obtain the form of plots of reactive pressures produced by the soil foundation on a strip loaded along its entire length with a uniformly distributed load. In determining the values ​​of reactive pressures and values ​​of bending moments, the data of a previously published work of one of the authors of the article, based on V.N. Zhemochkin method, is used. Analysis of the obtained calculation results showed that the shape of the plot of reactive pressures largely depends on both the index of flexibility of the foundation and the index of flexibility of the “strip-soil” system. The novelty of the research is that the calculation results are obtained using the traditional method of calculation (i.e., without taking into account the joint work of the “strip-soil” system and using 3 models of the soil base: linearly deformable half-plane, linearly deformable layer of finite thicknesses and the Winkler model. The obtained results of calculation will allow to design ground structures on the elastic foundation.
Estimation of the potential of energy efficiency increase in SMARTGRID systems with prosum-ers based on electric vehicles
Authors: Lutsenko Ivan , Fedoriachenko Sergey , Malienko Andrey , Rukhlova Natali , Koshelenko Evgen , Tsyhan Pavel , Kholodov Anton
Published: December 2021

The modes of operation of power transformer substations 6 (20)/0.4 kV are analyzed. Scientific and technical solutions for the use of electric vehicles as prosumers of electric energy are substantiated. The potential influence of electric cars on electricity losses in "smart" electric networks is determined. Feasibility study of expediency of using electric mobiles as prosumers from the standpoint of loss reduction and efficiency of network equipment use is given. Quantitative indicators of the potential of equalization of the daily schedule of electric loads of the typical area of consumers of city electric networks are determined. The main indicator is the reduction of electricity losses in transformers by 7-10% compared with the existing ones when regulating the mode from the side of 0.4 kV with help of electric vehicles. Additionally, the possibility of increasing the capacity of electrical networks up to 45% identified.
Influence of endotoxemy on development of non-alcoholic fatty liver disease
Authors: Fadieienko G. D. , Gridnyev O. E. , Kushnir I. E. , Chernova V. M. , Solomentseva T. A. , Nikiforova Y. V. , Kurinna O. G.
Published: December 2021

Objective — to investigate endotoxin levels and to assess the relationship between endotoxemia and metabolic parameters and the degree of steatosis and fibrosis in patients with non‑alcoholic fatty liver disease (NAFLD) against the background of metabolic syndrome (MS).

Materials and methods. The study included 68 patients with NAFLD with metabolic disorders and 20 people of the control group. Women prevailed in both investigational groups, the mean age was 49.34 ± 10.8 years. All patients underwent evaluation of their anthropometric parameters, investigation of body composition with determination of the percentage of visceral adipose tissue (VAT). To reveal VAT dysfunction, visceral adiposity index (VAI) was calculated with M. C. Amato method. Steatometry was performed by determining the wave attenuation coefficient and carrying out shear wave elastography. Endotoxin levels in blood serum were determined using a set of reagents «LAL Chromogenic Endpoint Assay» manufactured by «Hycult Biotech» (Netherlands).

Results. Bacterial endotoxin levels in peripheral blood in the examined patients were almost three times higher in comparison with the control group (p < 0.05). Patients with overweight and obesity had significantly higher endotoxin levels compared with the control group (p < 0.05). The significant increase in endotoxin levels has been defined in obese NAFLD patients compared to the NAFLD patients with normal weight (p < 0.05). The direct correlation was found between endotoxin parameters and parameters of abdominal and visceral obesity. In the group of patients with high VAT activity, the maximal values of this indicator were observed, which significantly differed from the corresponding indicator in patients with low and medium VAI (p < 0.05). There was a direct correlation between moderate endotoxin and insulin resistance, a direct weak relationship between endotoxin and lipid profile parameters. In patients with grade 2 and 3 steatosis, significant differences in the level of endotoxemia were observed compared with the control group (p < 0.05) and patients with grade 1 steatosis (p < 0.05). At high grades of liver fibrosis (F3F4) there was a tendency to reduce endotoxemia compared with the low‑grade fibrosis (p < 0.05).

Conclusions. The revealed relationships between endotoxemia level and metabolic factors of NAFLD development indicate the pathogenetic role of bacterial endotoxemia in triggering a cascade of metabolic reactions with the subsequent accumulation of lipids in the liver tissue and the progression of steatosis and fibrosis.