28 research outputs found
Concept and development of an autonomous wearable micro-fluidic platform for real time pH sweat analysis
No full textIn this work the development of an autonomous, robust and wearable micro-fluidic platform capable of performing on-line analysis of pH in sweat is discussed. Through the means of an optical detection system based on a surface mount light emitting diode (SMD LED) and a light photo sensor as a detector, a wearable system was achieved in which real-time monitoring of sweat pH was performed during 55 minutes of cycling activity. We have shown how through systems engineering, integrating miniaturised electrical components, and by improving the micro-fluidic chip characteristics, the wearability, reliability and performance of the micro-fluidic platform was significantly improved
Sharp estimates for the polynomial approximation in weighted Sobolev spaces
No full text© 2015, Pleiades Publishing, Ltd. We obtain sharp estimates for the accuracy of the best approximation of functions by algebraic polynomials on an interval, the half-line, and the entire line in weighted Sobolev spaces with Jacobi, Laguerre, and Hermite weights, respectively. We show that the orthogonal polynomials associated with these weights form orthogonal bases in the respective weighted Sobolev spaces. We obtain sharp estimates of Markov–Bernstein type
Sharp estimates for the polynomial approximation in weighted Sobolev spaces
No full text© 2015, Pleiades Publishing, Ltd. We obtain sharp estimates for the accuracy of the best approximation of functions by algebraic polynomials on an interval, the half-line, and the entire line in weighted Sobolev spaces with Jacobi, Laguerre, and Hermite weights, respectively. We show that the orthogonal polynomials associated with these weights form orthogonal bases in the respective weighted Sobolev spaces. We obtain sharp estimates of Markov–Bernstein type
Schemes of the finite element method with separation of singularity for a two-point boundary-value problem of the 4th order with degenerate coefficients
No full textIn this paper we construct a high accuracy variant of the finite element method for an ordinary differential equation of the fourth order whose coefficients are degenerate on the boundary. The proposed technique is based on the multiplicative and additive-multiplicative separation of singularity. We prove that the convergence rate of the proposed technique is optimal in a given class of smoothness of right-hand sides. © Allerton Press, Inc., 2011
Intensification of the students' self-development process when performing design and settlement works on the "machine parts" course
No full text© by The Author(s). The article addresses issues related to the methodology of intensifying self-development process when performing t design and settlement works on the "Machine Parts" course for the students studying in such areas of training as "Technology" and "Vocational Education" with the use of computer technologies. At the same time, there are formulated the required pedagogical conditions that must be provided to all participants of the educational process, and accordingly, there are disclosed methodological aspects of the design and settlement work performance by means of specialized computer software. This in turn makes it possible to intensify the students' self-development process during the study of the "Machine parts" course. To succeed in the intensification of the students' self-development process when performing design and settlement works on the "Machine Parts" course, there should be develop appropriate pedagogical conditions. The most effective implementation of this methodology may be performed through the usage of specialized computer software. There is provided a technology of designing two-stage parallel-shaft reduction gear unit based on specialized computer software Compass 3D. Implementation of specialized computer software when performing a course project on "Machine Parts" allows intensifying the self-development quality of students within the educational process
Intensification of the students' self-development process when performing design and settlement works on the "machine parts" course
No full text© by The Author(s). The article addresses issues related to the methodology of intensifying self-development process when performing t design and settlement works on the "Machine Parts" course for the students studying in such areas of training as "Technology" and "Vocational Education" with the use of computer technologies. At the same time, there are formulated the required pedagogical conditions that must be provided to all participants of the educational process, and accordingly, there are disclosed methodological aspects of the design and settlement work performance by means of specialized computer software. This in turn makes it possible to intensify the students' self-development process during the study of the "Machine parts" course. To succeed in the intensification of the students' self-development process when performing design and settlement works on the "Machine Parts" course, there should be develop appropriate pedagogical conditions. The most effective implementation of this methodology may be performed through the usage of specialized computer software. There is provided a technology of designing two-stage parallel-shaft reduction gear unit based on specialized computer software Compass 3D. Implementation of specialized computer software when performing a course project on "Machine Parts" allows intensifying the self-development quality of students within the educational process
Simulation of the effectiveness of longitudinal rectangular fins on the efficiency of the double pipe heat exchanger
No full textIn this article, a mathematical simulation of a double pipe heat exchanger is carried out, having the longitudinal rectangular fins with the dimension of (2*3*1000) mm, mounted on the outer surface of the inner tube of the heat exchanger. In this paper, the advantage of using of that type of fins and its effect on the effectiveness of the heat exchanger are studied with the help of the computer program. The carried out research allowsmaking the calculation to find the optimum design parameters of heat exchangers. The outer tube diameter is (34.1mm) while the inner tube diameter is (16.05mm). The tubes wall thickness is (1.5mm) and the model length was (1 m). The hot water is flowing through the inner tube in parallel with the cold water that passing the outer tube. The hot and cold water temperature at the inlet is (75°C & 30°C) respectively. The mass flow rate inside the central pipe is (0.1 kg/s) while the annular pipe carrying (0.3 kg/s). In the present work, the program ANSYS Workbench 15.0 was used to find out the results of heat transfer as well as the behavior of liquids inside the heat exchangers
Convectiv drying of disperesd materials before the thermochemical processing
No full textDrying of wood materials is one of the most important processes not only of wood processing, but also of many other industries. Drying processes involve the removal of moisture as a result of a phase transition from a liquid or solid to a gaseous state. This is due to the high energy intensity and duration of the process, especially for colloidal materials. The latter is due to the fact that with intensive drying the quality of the finished product often decreases, for example, when drying lumber cracks and warps occur, which is unacceptable in the manufacture of thermally modified products. In cases of thermochemical processing of dispersed materials, the quality of raw materials is determined only by the final moisture content of dispersed materials.Questions of heat and mass transfer during the drying of materials were carried out by Girsh M., Lykov A.V., Lurye M.V., Sazhin B.S., Dolinsky A.A., Golubev L.G., Rudobashta S.P., Shubin G.S., Romankov PG, Ginzburg A.S., Mikhailov N.V., Mushtayev VI. and etc. The paper deals with convective technology of dispersive materials. The zone of convective drying of dispersed materials is presented. Experimental and mathematical modeling of the drying process of wet dispersed materials before thermochemical processing was carried out. The results of theoretical and experimental studies of changes in temperature and humidity in the drying bin are presented. The nature of changes in temperature and humidity of dispersed particles in a drying bin was determined. The effective height of the layer in the counter-current dryer is determined by calculation, depending on the moisture content of the fuel and the temperature of the exhaust flue gases
Chemiluminescence during interaction of 1,2,4-trioxolanes and 1,2,4,5-tetraoxanes with iron compounds
No full textInhospital changes of left ventricular diastolic function in patients undergoing coronary bypass surgery
No full textAim. To evaluate changes of left ventricular (LV) diastolic function in patients with multivessel coronary artery disease before coronary artery bypass grafting (CABG) and in the early postoperative period (7-10 days), as well as to assess the relation- ship between diastolic LV dysfunction and postoperative atrial fibrillation (POAF).Material and methods. This original prospective study of included 50 patients undergoing CABG at the Cardiac Surgery Unit № 1 of the N. V. Sklifosovsky Research Institute for Emergency Medicine from December 2020 to December 2021. All patients underwent standard echocardiography before and after surgery. Diastolic function was assessed using the following parameters: septal mitral annulus velocity (e’septal), lateral mitral annulus velocity (e’lateral), the ratio of the peak early transmitral velocity to peak early diastolic velocity of the mitral annulus movement (E/e’), left atrial volume index (ml/m2), peak tricuspid regurgitation velocity (m/s), the ratio of the peak early to late filling velocity (E/A).Results. After CABG, 35 patients maintained sinus rhythm in the early postoperative period (group 1), while 15 patients had POAF (group 2). According to echocardiography, type 1 diastolic dysfunction prevailed in both groups; types 2 and 3 LV diastolic dysfunction were not identified. Among the parameters characterizing myocardial relaxation, in group 1 after CABG, a significant increase in the peak E (p=0,001) was noted, and due to this, the normalization of the E/A ratio was recorded (p<0,0001). An increase in e’lateral (p=0,05) was also revealed, in connection with which an increase in the E/e’ (p=0,02) was noted. In the group of patients with POAF, such changes were not detected. Left atrial volume index (ml/ m2) was significantly higher in the POAF group (p=0,02).Conclusion. Surgical myocardial revascularization has a positive effect on LV diastolic function. Improvement in LV diastolic function after CABG may be a sign of the restoration of hibernating myocardium function, while the absence of LV diastolic function improvement, together with left atrial dilatation, may be predictors of early POAF
