Analysis and prediction of copper surface roughness obtained by selective laser melting

The paper presents the results of experimental studies of the effect of mechanoactivation of the powder, argon shielding gas and the effect of technological modes of melting: the speed of the laser beam, the power of laser radiation, the scanning step, the preliminary temperature of heating the powder material on the surface roughness of the copper powder material obtained by selective laser melting. Experiments on the melting of copper powder are implemented on the installation of layer-by-layer laser melting of the original design, which allows to adjust all technological modes of melting. The surface roughness is determined on the non-contact digital microscope Olympus LEXT OLS4100. The mathematical dependence of the surface layer roughness of copper powder on the technological modes of melting is obtained on the basis of the theory of experiment planning and static processing of the results. The significant parameters of the regime-the power of laser radiation, the speed of the laser beam, the scanning step affecting the roughness of the layer. The positive effect of mechanical activation of powder material and protective atmosphere on the quality of the surface layer is shown

Iron-free electron synchrotron with weak focusing

A synchrotron construction the magnetic field of which is without steel core is suggested. Acceleration chamber is combined with magnetizing winding. The described version of accelerator is favorably different in small weight, simplified production and assembling technique

The simulation of three-dimensional bar systems by the finite element method Моделирование пространственных стержневых систем методом конечных элементов

The article considers the representation of framed building as a three-dimensional bar system and simulation of obtained bar system by the finite element method. Underway the bar state equations and the equations system solution in the Cauchy form were obtained. Also article deals with obtaining of stiffness matrix linking nodal forces and nodal displacements. The obtained results are applicable for both the statically determinate systems and the statically indeterminate ones.<br>Рассмотрено представление конструкции каркасного здания пространственной стержневой системой и моделирование полученной стержневой системы методом конечных элементов. Составлены уравнения состояния стержня и получено решение системы уравнений в форме Коши. Получена матрица жесткости, связывающая узловые силы и узловые перемещения. Полученные результаты применимы как для статически определимых, так и для статически неопределимых систем

Russians in Dairen

How Russian emigrants preserved the Russo-Japanese war monuments in Dairen. The history of the Russian community in Dairen is described

Artificial olfactory system for multi-component analysis of gas mixtures.

Gas analysis is an important part of our world and gas sensing technology is becoming more essential for various aspects of our life. A novel approach for gas mixture analysis by using portable gas chromatography in combination with an array of highly integrated and selective metal oxide (MOX) sensors has been studied. We developed a system with small size (7 x 13 x 16 inches), low power consumption (~10 W) and absence of special carrier gases designed for portable field analysis (assuming apriori calibration). Low ppb and even sub-ppb level of detection for some VOCs was achieved during the analysis of 50 ml of gas samples. A detailed description of our innovative design of multi-sensory platforms based on MOX sensors for multidimensional portable gas chromatography is provided in detail in this work. As a part of this effort, we successfully synthesized nanocomposite gas sensors based on SnO2 for selective detection of hydrogen sulfide, mercaptans, alcohols, ketones and heavy hydrocarbons. The morphology of the prepared sensors was closely studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), transition electron microscopy (TEM) and X-Ray diffraction (XRD). Optical and electrical properties of polycrystalline SnO2 were investigated by using UV-Vis spectroscopy, transmission line measurement (TLM) and four probe resistance measurement techniques. Furthermore, more advanced gas sensing performance for detection of benzene, toluene, ethylbenzene, and O-xylene (BTEX) of polycrystalline SnO2 film (30 nm) coated with bimetal Au:Pd (9:1 molar ratio) nanoclusters was measured. Finally, besides the experimental result, the theoretical validation of the detector’s performance was provided based on high catalytic activity of nanocomposite materials and its superior electronic structure for gas detection compared to the polycrystalline SnO2. The theoretical background of gas chemisorption process at the surface of polycrystalline SnO2 was reviewed in this work. Furthermore, one dimensional Poisson equation relates surface energy states ( and ) and the bulk electronic structure ( and ) of polycrystalline SnO2. The main theory of electronic processes on the surface of semiconductors during the gas chemisorption was further applied in a case of nanocomposite materials

Visit to India

https://stars.library.ucf.edu/prism/1053/thumbnail.jp

Interim Results of Studies of the Royal Remains from the Necropolis of the Ascension Cathedral of the Moscow Kremlin

The purpose of this article is to comprehend the results of the study of the remains from the burials of the female necropolis of the Ascension Cathedral by the historical necropolis research group 1994-2010 formed on the basis of the Moscow Kremlin Museum-Reserve This article reflects the main milestones of anthropological study of the remains of historical figures in the Soviet period of Russian history and in modern times A special place is given to the history of the origin and evolution of the method of reconstructing a person s appearance on a craniological basis Gerasimov s method This technique was the result of the development of biological historical archaeological and social disciplines that consider a person in all its complex diversity history anatomy anthropology paleoanthropology and archeolog