Refinement of the method for selecting the width of the conductor of printed circuit boards on a metal base, working in the absence of convection

The article proposes a refined method for calculating the width of the conductors of printed circuit boards on a metal base for the onboard devices of spacecraft, depending on the current flowing. The constructed refined mathematical model of the process of conductive heat exchange between the conductors and the metal base is described. The results of calculations of various, most common, locations of layers of printed circuit boards are presented. An analysis was carried out and a refined methodology was developed based on the results obtained. It allows you to easily (without complicate calculations) calculate the necessary values of the width of conductors. This technique is based on graphical methods, but allows you to perform technical calculations with sufficient accuracy. Accuracy is achieved by using special formulas that simplify the determination of the value of a physical quantity on a logarithmic scale. The disadvantages of the proposed method are indicated.

Refined method for determining the current agricultural machinery tire wearing surface area

It has been established that the predictive assessment of the level of impact on the soil of tractors and agricultural machines is based on the calculation of the specific pressure equal to the ratio of the vertical load to the propeller contact surface area. A mathematical model is proposed that has been developed based on the results of field tests of a large number of samples of agricultural tires. The adequacy of the model was assessed using the Nash-Sutcliffe efficiency coefficient.

Indentation mapping of stretched adhesive membranes

Unilateral adhesive contact between a rigid indenter and a uniformly stretched membrane of arbitrary shape is considered. The generalized Johnson–Kendall–Roberts (JKR)-type and Derjaguin– Muller–Toporov (DMT)-type models of non-axisymmetric adhesive contact are presented for short- and long-range adhesion, respectively, and the JKR–DMT transition is established in the framework of the generalized Maugis–Dugdale model. A refined method of matched asymptotic expansions is applied to construct the leading-order asymptotic model for indentation mapping of freestanding two-dimensional materials with an axisymmetric probe, using the approximate analytical solution obtained in explicit form for an infinite membrane in the limit of short-range adhesive contact with an indenter in the form of an elliptic paraboloid. The cases of a spherical indenter and a rectangular membrane are studied in detail.

An ultrasound-guided injection method for a syngeneic orthotopic murine model of breast cancer

Breast cancer is the most common cancer among women worldwide. For high-risk women, contrast enhanced (CE)-magnetic resonance imaging (MRI) is recommended as supplemental screening together with mammography. The development of new MRI contrast agents is an active field of research, which requires efficacy tests on appropriate preclinical pathological models. In this work, a refined method to orthotopically induce breast cancer in BALB/c mice was developed using ultrasound (US) as a guide for the precise localisation of the tumour induction site and to improve animal welfare. The method was coupled with CE-MRI to characterise the evolution of the tumoural lesion.

Experimental and Theoretical Study of Heat Losses in Drying Cylinders

The research purpose is to develop methods for determination of heat losses in drying cylinders. Experimental study of temperature of drying cylinders performed in the drying section of a paper machine during its steady-state operation. Medium, maximum and permissible statistical characteristics of drying cylinder temperatures were defined. The drying cylinders with increased condensation concentration were determined by the minimally permissible temperature levels and the repair of the condensation drainage system to reduce heat losses (steam consumption) was justified. The cause of uneven dryness of the paper web across the width has been determined. The condensate ring on the inner wall at the edges of the drying cylinders gets thickened due to moisture coming from the end caps from the action of centrifugal forces. The condensation is removed from the drying cylinders with a siphon on the drive side. Therefore, on the front side of the drying cylinders condensate film has a greater thickness, and the paper web dries worse. The single-sided condensate disposal and the physical effect of centrifugal condensate runoff from the end caps to the side inner surface of the drying cylinders cause a lower dryness from the front side of the paper web. The use of thermal insulation of end caps will contribute to uniform dryness across the width of the paper web. The results of experimental studies were processed by methods of mathematical statistics in order to describe the thermal losses during contact drying of the paper web on drying cylinders with and without thermal insulation of the end caps to the ambient air. The calculation of heat losses is carried out according to the refined method of researching thermal processes in contact drying of paper web. It is found, that the use of thermal insulation of the end caps of the drying cylinders provides a reduction in steam consumption for contact drying of the paper web without affecting the technological process. The research results can be used to reduce heat losses in the drying section of paper machines on cylinders that do not have thermal insulation of the end caps. For instance, for a paper machine consisting of 56 cylinders with a diameter of 1500 mm and a capacity of 7000 kg/h of absolutely dry paper, insulating their end caps saves up to 223 kg/h of steam for drying the paper web. Methods of detection of drying cylinders with increased content of condensation on permissible levels of temperature is developed and approved. A refined method for determining thermal losses during contact drying of the paper web on drying cylinders has been developed.