Хімічна метрологія, стандартизація та сертифікація: методичні рекомендації до лабораторних робіт

Методичні рекомендації містять пояснювальну записку, навчальну програму курсу, лабораторні роботи, задачі, довідкові дані, список цитованої літератури. Рекомендовано студентам хімічного факультету.Методичні рекомендації до лабораторних робіт для студентів хімічного факультету за напрямом підготовки 6.0501301 “хімічна технологія

Хімія поверхнево-активних речовин в харчовій та косметичній промисловості: методичні рекомендації до лабораторних робіт для студентів хімічного факультету

Методичні рекомендації містять пояснювальну записку, навчальну програму курсу, лабораторні роботи, контрольні запитання, список використаної та рекомендованої літератури. Рекомендовано студентам хімічного факультету за напрямом підготовки 6.051301 “хімічна технологія”. Призначення методичних вказівок полягає в тому, щоб не лише дати уявлення студентам про будову, класифікацію, властивості поверхнево-активних речовин (ПАР), використання ПАР в різних галузях промисловості, але й ознайомити з експериментальними методами їх дослідження

Токсикологічна хімія харчових добавок та косметичних засобів

Методичні рекомендації містять пояснювальну записку, навчальну програму курсу, лабораторні роботи, питання для підготовки до модульного контролю, список використаної та рекомендованої літератури. Рекомендовано студентам хімічного факультету за напрямом підготовки “хімічна технологія

Основи матеріалознавства:

Методичні рекомендації містять пояснювальну записку, навчальну програму курсу, лабораторні роботи, контрольні запитання для перевірки знань. Рекомендовано студентам хімічного факультету спеціальностей 161 «Хімічні технології та інженерія» та 102 “Хімія”

Construction of an Algorithm for the Selection of Rigid Stops in Steel­concrete Beams Under the Action of A Distributed Load

An algorithm has been developed to select rigid stops in steel-concrete beams under the action of distributed load. Concrete is connected rigidly to a steel sheet in order to perform the joint operation of the concrete and steel sheet. Such a connection in the beam is provided by rigid stops that prevent shifting efforts in the concrete and steel contact area. The efforts are determined through the turning angles between the two adjacent sections of the beam. A graph-analytical method for determining movements is used to determine the turning angles. In determining the deformations of a steel-concrete beam, the calculation is based on the reduced rigidities of cross-sections.The purpose of this study is to optimize the structure of a steel-concrete beam by selecting the rational number and arrangement of rigid stops. This optimization would allow a more rational utilization of the structure's material ‒ concrete and steel. That would reduce the cost of operations and the quantity of materials required in the production, installation, and operation of the considered structures.An earlier proposed algorithm for the selection of rigid stops in steel-concrete beams under the action of a concentrated force has been expanded for the case of an evenly distributed load. When selecting the number of rigid stops, it is assumed that the magnitude of the distributed load acting on a beam, the mechanical characteristics of materials (steel and concrete), as well as the span of the beam and the size of its cross-section, are kNown. In contrast to the beams with a concentrated force in the middle, where the forces abide by a linear law, in the beams with an evenly distributed load the efforts in a steel strip change in line with a square parabola. Therefore, while the same step has been obtained for stops, it is not possible to achieve a situation at which efforts in all stops have the same valu

Revealing Changes in the Technical Parameters of the Teat Cup Liners of Milking Machines During Testing and Production Conditions

To implement effective cow milking, it is necessary to take into account the peculiarities of the milk flow process, the milking machine's adaptability to perform the given technological functions. The aim of research is to establish changes in the design and technological parameters and physical and mechanical properties of teat cup liner of milking machines during its testing and in production conditions. The results obtained will make it possible to make a rational choice of rubber, ensure an efficient milking process during its service life. It is found that the tensile strength of silicone teat cup liner at the beginning of operation was 1.6 times higher than that of a rubber compound, and after 6 months. operation – 1.7 times. With respect to the relative elongation, this difference was 1.4 times, and after operating time – 1.3 times. Studies have proven that rubber during operation changes its physical and mechanical properties: the length of the active part increased by 3.1 mm; wall thickness – 0.2 mm. It is found that the most intensively elastic properties of teat cup liner changed during the first 10–20 days. After 10 days, the closing vacuum increased by 16.6 % compared to the initial one, and after 20 days by 23.3 %, which amounted to 8.57 and 9.06 kPa, respectively. Up to 420 hours of operation, the clamping vacuum reached 11.3 kPa, which is 5.8 % lower than the requirements for toughening teat cup liner for rejection. In general, over the period of experiments, the average value of the vacuum of closing the opposite walls of teat cup liner increased from 7.35 to 12.43 kPa, which is 3.6 % higher than the norm (12 kPa). As a result of experimental studies, the regularity of the rubber tension force depending on the operating time in the form of a fourth degree polynomial is obtained. It is found that after 150 hours of operation, the tensile force of teat cup liner decreased by 21 

Improving the Algorithm of Choosing Spacing and Number of Stiff Supports Against A Concentrated Force in Steel-concrete Beams

A steel-concrete beam was taken as the study object. The algorithm of selecting the number of stiff supports for the steel-concrete beam loaded with a concentrated lateral force in the middle of the span has been refined. Stiff supports served to join the steel strip with concrete to ensure their joint performance. The algorithm was refined based on the condition of equality of the longitudinal force in the steel strip from the action of the calculated load and the maximum longitudinal force obtained after setting the supports. In this case, the longitudinal forces in all stiff supports, as well as the spacing of the stiff supports should be the same. A disadvantage of the known algorithm consists in the complexity of determining the coefficient φb2 taking into account the effect of long-term concrete creep on the element deformation without cracks. This coefficient fluctuates widely and depends on many factors. Besides, it is also insufficiently studied. Calculations for determining the number and spacing of stiff supports in a steel-concrete beam were conducted according to the proposed algorithm and in the Lira software package. The forces acting on the supports and spacing of the supports were the same. The force acting in the support was 8941.5 N. When selecting characteristics of the steel-concrete beam, maximum longitudinal force in the steel strip was obtained. The longitudinal force amounted to 35726 N. The same longitudinal force was obtained from the diagram of longitudinal forces obtained after setting the supports. This study was aimed at improving the design of steel-concrete beams. A rational number and placement of stiff supports ensure savings: the required amount of building materials is reduced and their cost is reduced due to cutting labor costs for their manufacture and operatio