Formation of the Transition Zone "Matrix Alloy - Reinforcing Granules" in the Process of Solid-Liquid Synthesis of Composite Material

Casted composite materials have found certain application in mechanical engineering. Their advantages are lower cost due to the use of casting technology (solid-liquid synthesis), absence of any restriction on the shape and weight of parts. It is known that the transition zone between the matrix alloy and reinforcing phase plays an important role on the level of mechanical properties of cast composites. So, the aim of the study is investigations of transition zone formation during the infiltration of matrix alloy into the frame formed by the reinforcing phase. Copper based alloy was used as a matrix alloy and cast-iron granules were used as a reinforcing phase. Cast composite materials have been exposed for different time during the synthesis. Specimens were studied using electron microscopy. Results on the concentration distribution of main elements (Si, Fe, Cu) in a transition zone are presented. It is shown that the formation of transition zone starts during the infiltration process with further its growth during the exposition at the synthesis temperature. It is established that the formation of the transition zone takes place not only due to elements diffusion but as well due to the dissolution of granules of reinforcing phase. Experiments carried out allow establishing some peculiarities of the transition zone formation. To achieve required level of mechanical properties it is necessary to control the melt temperature and duration of the synthesis of cast composite materials

Influence of heat and laser treatment on the structure and properties of R6M5 high-speed steel

The influence of laser treatment on the structure, microhardness and residual stresses in the surface layers of high-speed tool steel R6M5 is investigated. It is shown that laser treatment, carried out as a finishing operation of thermal hardening, can significantly change the structure and properties of steel R6M5. The modes of hardening treatment, which provide an improved combination of properties, due to the uniform distribution of residual austenite and martensite, are determined. This helps to increase the endurance of steel R6M5 when exposed to its surface pulsating contact stresses

Identification of Nedd4 E3 Ubiquitin Ligase as a Binding Partner and Regulator of MAK-V Protein Kinase

MAK-V/Hunk is a scantily characterized AMPK-like protein kinase. Recent findings identified MAK-V as a pro-survival and anti-apoptotic protein and revealed its role in embryonic development as well as in tumorigenesis and metastasis. However molecular mechanisms of MAK-V action and regulation of its activity remain largely unknown. We identified Nedd4 as an interaction partner for MAK-V protein kinase. However, this HECT-type E3 ubiquitin ligase is not involved in the control of MAK-V degradation by the ubiquitin-proteasome system that regulates MAK-V abundance in cells. However, Nedd4 in an ubiquitin ligase-independent manner rescued developmental defects in Xenopus embryos induced by MAK-V overexpression, suggesting physiological relevance of interaction between MAK-V and Nedd4. This identifies Nedd4 as the first known regulator of MAK-V function

Аналіз математичних моделей зміни курсу судна при повороті

Mathematical models of changing the course of a vessel when turning without taking into account the duration of putting the rudder blade over are presented. All in all, three models of different degree of adequacy to the actual turning process were explored, and the correspondence of mathematical models to the experimental field observations of specific vessels was revealed. Analytical expressions for calculating the duration of both phases of a turn by the method of simple iterations were obtained.An analysis of mathematical models under consideration was conducted for the purpose of identifying the model, most adequate to the actual process of the vessel’s turn. As a result of the imitation simulation of the vessel’s turn to 90°, whose inertial characteristics of turning ability were obtained from the field observations, it was established that when using mathematical model of the first type for the prediction of the curvilinear section, the trajectory error was 150¸200 m, for the second type of the model this value was 35¸40 m, and for the third type – 25¸30 m. The mathematical model of the vessel’s turning ability of the third type proved to be the most acceptable, since along with sufficient simplicity it possesses the required accuracy (maximum divergence of experimental and model trajectories is 25¸30 m.Results of the study can be used in navigation information systems for developing the function of calculation of parameters of the vessel’s turn for the assigned initial data.Приведены математические модели изменения курса судна при повороте без учета времени перекладки пера руля. Всего рассмотрено три модели разной степени адекватности реальному процессу поворота и выявлено соответствие математических моделей экспериментальным натурным наблюдениям конкретных судов. Получены аналитические выражения для расчета продолжительности обоих фаз поворота способом простых итерацийНаведено математичні моделі зміни курсу судна при повороті без урахування часу перекладання пера керма. Всього розглянуто три моделі різного ступеня адекватності реальному процесу повороту і виявлено відповідність математичних моделей експериментальним натурним спостереженням конкретних суден. Отримано аналітичні вирази для розрахунку тривалості обох фаз повороту способом простих ітераці

Analysis of Mathematical Models of Changing the Vessel's Course When Turning

Mathematical models of changing the course of a vessel when turning without taking into account the duration of putting the rudder blade over are presented. All in all, three models of different degree of adequacy to the actual turning process were explored, and the correspondence of mathematical models to the experimental field observations of specific vessels was revealed. Analytical expressions for calculating the duration of both phases of a turn by the method of simple iterations were obtained.An analysis of mathematical models under consideration was conducted for the purpose of identifying the model, most adequate to the actual process of the vessel's turn. As a result of the imitation simulation of the vessel's turn to 90°, whose inertial characteristics of turning ability were obtained from the field observations, it was established that when using mathematical model of the first type for the prediction of the curvilinear section, the trajectory error was 150¸200 m, for the second type of the model this value was 35¸40 m, and for the third type – 25¸30 m. The mathematical model of the vessel's turning ability of the third type proved to be the most acceptable, since along with sufficient simplicity it possesses the required accuracy (maximum divergence of experimental and model trajectories is 25¸30 m.Results of the study can be used in navigation information systems for developing the function of calculation of parameters of the vessel's turn for the assigned initial data