Про крихке руйнування тіла з частково залікованою зірчастою тріщиною

In this article, the express methodology for assessing the strength of a brittle material with a partially healed crack is used to model the renovation of a body with a star-shaped defect of a cyclically symmetrical structure. The rheology of the joint layer is not taken into account, but the specific surface energy in the healed area is generally different than in the solid body. Therefore, we have the problem of crack mechanics in a body that is homogeneous in terms of elastic properties and heterogeneous in terms of crack resistance. The degree of crack healing was described by two parameters: the ratio of the crack resistance of the joint and body materials and the ratio of the length of the healed area to the length of the initial crack. The subject of the analytical study was the efficiency of healing - the ratio of ultimate loads of brittle failure for a healed and primary crack. Two treatment options are considered in detail: near the peaks and near the center of the star defect. Pages of the article in the issue: 100 - 103 Language of the article: UkrainianЕкспрес-методика оцінки міцності тіла з частково залікованою тріщиною використовується для моделювання реновації тіла із зіркоподібним дефектом циклічно-симетричної структури. За розв’язками задачі механіки тріщин у однорідному за пружними властивостями та неоднорідному за тріщиностійкістю тілі дослідили залежності ефективності заліковування від ступеня заповнення тріщини та від якості з’єднувального шару. Детально розглянуто два варіанти заліковування: поблизу вершин та поблизу центра зірчастого дефекту

Classification of bad pixels of the Hawaii-2RG detector of the ASTROnomical NearInfraRed CAMera

ASTRONIRCAM is an infrared camera-spectrograph installed at the 2.5-meter telescope of the CMO SAI. The instrument is equipped with the HAWAII-2RG array. A bad pixels classification of the ASTRONIRCAM detector is proposed. The classification is based on histograms of the difference of consecutive non-destructive readouts of a flat field. Bad pixels are classified into 5 groups: hot (saturated on the first readout), warm (the signal accumulation rate is above the mean value by more than 5 standard deviations), cold (the rate is under the mean value by more than 5 standard deviations), dead (no signal accumulation), and inverse (having a negative signal accumulation in the first readouts). Normal pixels of the ASTRONIRCAM detector account for 99.6% of the total. We investigated the dependence between the amount of bad pixels and the number of cooldown cycles of the instrument. While hot pixels remain the same, the bad pixels of other types may migrate between groups. The number of pixels in each group stays roughly constant. We found that the mean and variance of the bad pixels amount in each group and the transitions between groups do not differ noticeably between normal or slow cooldowns.Comment: 11 pages, 7 Figures, 3 table

On dissipation in junction of pin with cone under cyclic loading

Проведено порівняльний якісний аналіз роботи двокомпонентного та трикомпонентного з’єднань “шарошка-зубець” з урахуванням мікропроковзування під циклічним навантаженням. Розглянуто реологічні моделі з’єднань як систем із зосередженими параметрами. Пропонований підхід допускає аналітичне описання фізичних співвідношень за будь-якої програми немонотонного навантаження. Описано розсіювання енергії у фрикційному контакті та побудовано петлі конструкційного гістерезису. Встановлено залежність величини розсіяної енергії від порогового значення сили зрушування. Виявлено зменшення дисипації енергії у фрикційних контактах трикомпонентного з’єднання з оптимально підібраними натягами відносно двокомпонентного з’єднання з оптимальним натягом. Наведено приклади розрахунку. Проведений аналіз підтвердив сприятливий вплив раціонально спроектованої додаткової втулки на підвищення довговічності озброєння бурових шарошкових доліт.The problem of rational design of cone bits carbide-tipped armament for oil and gas industry needs is being considered. Previously the authors had found a significant increase of load capacity of pressure coupling with intermediate elastic sleeve under the impact of monotonous static load. In the presenedt article a comparative qualitative analysis of two-component and three-component junctions "pin-cone" under the impact of cyclic loading has been carried out taking into account the microslip in frictional contacts. Rheological models of compounds are considered as systems with lumped parameters, which are built using the Hooke’s and Saint-Venant’s elements. The proposed approach allows analytical description of the physical relationship for any program of nonmonotonic loading.The equations of curves of unloading and then repeated loading have been obtained basing on the Masing’s principle from the formulas for the active load. For zero-to-compression stress cycle the energy dissipation in frictional contact have been described and loops of construction hysteresis have been built. For both variants of the considered structures the dissipated energy values dependence on the force threshold values, when moving starts, has been found. The decrease of energy dissipation in frictional contact three-component compounds with optimally selected tightness relative to two-component compounds with optimal tension is shown. The examples of calculation are given for pressure coupling in the case, when both sleeve and toothed wheel are made of the same materials. The results of the calculation testify that, in the case when the load capacity for the optimal design of three-component compound under one-act load is 30% higher than the same for the two-component compounds, the threshold value of microslip moving start effort for design with a bushing is only in 20% higher than the same value for construction without a bushing. Smaller effect is explained by the fact that three-component optimal design,t constructions is optimized for strength balance by equivalent stresses, but not for the tangential stresses in contacts. The analysis testified the favorable effect of the rationally designed bushing on the reduce of the rate of contact wear and, consequently, on the improvement of armament of roller cone drill bits durability. To improve the analytic estimations obtained the numerical analysis for the optimization by most durability criteria for the contacting objects should be used taking into consideration the model with distributed parameters by elastic-plastic deformation

Assessment of News Items Objectivity in Mass Media of Countries with Intelligence Systems: the Brexit Case

The role of mass media in society keeps the problem of manipulative influence distinction and the contiguous phenomena, chief among which is objectivity and authenticity of news items, current. The research provides a detailed study of the information broadcasting mechanisms in the media area, defines the problems, impeding an impersonal reproduction and disclosure of information, clarifies the verification methods, and gives their topology. In this research, we examined how the mass media of different countries presented the same event to the public. The publications of four mass media, concerning such an event as the withdrawal of the United Kingdom from the European Union (Brexit), have been determined as an object of the analysis. The chosen mass media refer to the countries, which are not the direct participants of that process: Russia, the USA, and Ukraine. D. Brewer’s criteria were used to define the objectivity of the news items. A relative sentiment of the news, which became the objective analysis basis, has been identified using linguistic rate with Eureka Engine intelligence system. The obtained results predominantly confirmed the hypothesis, that the mass media of different countries would represent the process of the UK withdrawal from the EU according to the country’s policy and interpret the facts in their favor. All the four mass media demonstrate the partiality when broadcasting the current situation in the matter of Brexit. The concepts being the semantic kernel elements of mass media publications have emotional coloring. The sentiment analysis of the publications resulted in the conclusion that only one of the four mass media gave a neutral assessment of the Brexit situation. The other three held to the political stance of their edition or government. The research results indicate that the problem of mass media objectivity remains relevant. The correctional impact on public opinion through mass media is extremely high. Therefore, forming the personal attitude toward the situation or event should occur with using several verifications methods and mass media sources at once

Оценка рисков медицинского облучения при рентгенографических исследованиях детей

The use of the effective dose (the concept of which was developed for radiation protection of workers and public) and the nominal risk coefficients, averaged by sex and age, to assess the radiation risks of medical exposure has some significant limitations. Age and sex distribution of the staff and the entire population may be quite different from the sex and age distribution of patients undergoing medical exposure. Moreover, the structure of the age and sex of patients may be different for various medical examinations. There are simplified methods for evaluating individual risk for patients undergoing medical exposure. The methods are based on the effective dose evaluation and those take in to account age and gender. A more accurate assessment of lifetime risk of delayed stochastic effects for health of the patient is achieved by using the organ doses and the age and gender risk factors. The aim of this work was evaluation of the lifetime risk of long-term stochastic health effects for different gender and age groups of children undergoing various radiographic investigations by using organ doses and the age and gender risk factors, and subsequent classification in accordance with generally accepted international risk scale. Data from surveys of33 X-ray units in 29 specialized pediatric health care organizations in Russia were used in the work. Organ doses and patient’s effective doses were calculated on the basis of the defined for each x-ray machine typical modes for the 12 radiographic procedures (X-ray exam of the skull, chest, cervical spine, thoracic spine, lumbar spine–all in two projections – of the abdomen and pelvis – both in one projection)using a computer program PCXMC., Radiation risks for selected studies were estimated using the obtained organ doses and the age and gender risk factors calculated for the Russian population. The radiation risks were classified according to the international scale of the risks. It was found that the risk dependence on the sex and age is significant. For a number of examinations ,the gender dependence prevail; higher risks are intrinsic to female. For others examinations, a strong dependence on the age was revealed, such as an increase of the risk for the middle age group of children (10-14 years) compared to the younger and older groups.Использование эффективной дозы (концепция которой разработана для системы радиационной защиты работников и населения) и номинальных коэффициентов риска, усредненных по полу и возрасту, для оценки рисков медицинского облучения имеет ряд существенных ограничений. В частности, половозрастные распределения персонала и всего населения существенно отличаются от половозрастного распределения пациентов, подвергающихся медицинскому облучению. К тому же половозрастной состав пациентов может быть различным для различных медицинских исследований. Существуют упрощенные способы оценки индивидуального риска у пациента, подвергающегося медицинскому облучению, с учетом пола и возраста и использования эффективной дозы. Для более корректной оценки пожизненного риска отдаленных стохастических последствий для здоровья пациента необходимо использовать значения органных доз и половозрастные коэффициенты риска. Целью настоящей работы являлась оценка пожизненного риска отдаленных стохастических последствий для здоровья различных по полу и возрасту групп детей, подвергающихся рентгено-графическим исследованиям, на основе значений органных доз и половозрастных коэффициентов риска, с последующей его классификацией в соответствии с международной шкалой риска. В работе использовались результаты обследований 33 рентгеновских аппаратов в 29 специализированных детских медицинских организациях России. На основании определенных для каждого аппарата типичных режимов проведения 12 hентгенографических процедур (рентгенография черепа, органов грудной клетки, шейного отдела позвоночника, грудного отдела позвоночника, поясничного отдела позвоночника – все в двух проекциях; органов брюшной полости и таза – обе в одной проекции) были рассчитаны поглощенные дозы в органах и эффективные дозы пациентов с помощью компьютерной программы PCXMC. Используя полученные органные дозы и половозрастные коэффициенты риска, рассчитанные для российской популяции, оценивали радиационные риски для выбранных исследований, а затем классифицировали согласно международной шкале рисков. Установлено, что зависимость риска от пола и возраста весьма значительна. Для ряда исследований явно выражена гендерная зависимость: для женского пола характерны более высокие риски. Для других исследований выявлена сильная зависимость риска от возраста, с максимумом в средних возрастных группах детей (10–14 лет)

About bending of plate on inhomogeneous vinkler foundation

Розглядається задача згину пластинки на неоднорідній вглиб вінклерівській основі. Досліджено вплив армування основи на несучу здатність оксидного покриття під локальним навантаженнямThe problem of the local bending of a plate on inhomogeneous deep into foundation is considered. The Influence of the substrate sheathing on a carrying capacity of a covering in the local loading has been investigated