Development of the design of a new working section cooled by a dispersed coolant flow for a stand with induction heating

The paper presents a description of the design of a new working section cooled by a dispersed coolant flow for a stand with induction heating. The choice of the material of the working area and the method of spraying has been substantiated. The first commissioning experiments were carried out in a stationary cooling mode, with the parameters of the coolant p = 1.7 · 105 Pa, G = 3.8 · 10-3 kg/s.

Slotting mechanization for intensive garden planting

The paper presents a structure diagram of a slot trencher when planting a garden, consisting of a frame on which working sections, a bevel gear reducer and support wheel stands are fixed. On the working section there is a shaft with a working body - a disk slot cutter. It is made in the form of a disc with teeth, one cutting edge of each tooth is straight and the other edge is parabolic. On the parabolic edge the working elements are fixed in the form of knives with a cutting edge consisting of two parts. A straight one is along the periphery; the other is in the form of a guide along the entire length of the curved edge of the tooth and equal to the width of the cutting edge of the knife. The theoretical substantiation of the main structure parameters is carried out as a result of which the length of the inclined knife is determined, which allows satisfying the operating conditions of the device.

The low acoustic noise and turbulence wind tunnel of the University of Sao Paulo

This paper introduces the Low Acoustic Noise and Turbulence (LANT) wind tunnel of the Sao Carlos School of Engineering, University of Sao Paulo (USP-EESC), Brazil. The closed-loop wind tunnel features several devices to improve flow uniformity, reduce swirl, and lower the background acoustic noise and turbulence, enabling stability and aeroacoustic experiments. The design criteria was based on the best practices reported, in particular for low turbulence wind tunnels. Yet, these criteria are conflicting and we discuss the decisions that had to be made and present flow quality results that were achieved. The 16-bladed axial fan with 13-blade stators is driven by a variable-speed electric motor. At the corners, 100 mm dense acoustic foam is installed on the vertical walls, floor and ceiling, and the turning vanes are filled with acoustic-absorbing material. The long settling chamber contains a 3.175 mm mesh hexagonal honeycomb and five fine mesh nylon screens, ending in a 7:1 area ratio short contraction. The 3-m long closed-working section has a $1\times 1\ {\rm m}^2$ cross-section area. At 15 m/s the working section wall boundary layer is less than 100 mm thick, providing an area of at least $800\times 800\ \mathrm{mm}^2$ where the streamwise flow uniformity was within 1%. In the 10–30 m/s flow speed range, the turbulence intensity ranged from 0.05% to 0.071% and the background acoustic noise level, obtained with an inflow microphone, ranged from 90 and 110 dB. A benchmark experiment on a flat plate boundary layer produced an almost perfect two-dimensional Blasius profile up to $Re_x \approx 2.5 \times 10^6$ . A beamforming benchmark experiment on aeroacoustics accurately identified the sound emitted by a cylinder immersed in the flow.

Grounding of Design and Technology Parameters of Combined Coulter Furrow Opener of Precision Seed Drill

A formation of a seedbed is an important step during seed sowing process. A quality of seedbed formation influences on seeds distribution along both a row and a depth and is triggering the opportunity to obtain early and even sprouts. The design of the furrow opener is the main element that has a direct impact on the qualitative formation of seedbed and technological parameters of coulter operation. During the research, there has been analyzed the modern construction of precision seed drills coulters and specified advantages and disadvantages of their operation. It has been established that the most advanced are coulters having a working section with a combined angle (sharp and obtuse) of entry into the soil. The attained results afforded to develop an improved design of the coulter furrow opener of the precision seed drill. There was brought forward a combined wedge furrow opener, the upper part of which has a working section with a sharp angle of entry into the soil, lower - and compactor, located in the rear part of the furrow opener, which forms seedbed has a working surface with an obtuse angle of entry into the soil. There were obtained analytical dependences targeted to determine the main structural and technological parameters of the operating elements of a combined coulter furrow opener which is used to seed cultivated crops: the angles of entry into the soil of the upper and lower part of the furrow opener, compactor in the rolling plane and the angle of tip of the furrow opener in the horizontal plane.

The Concept of the Constructional Solution of the Working Section of a Robot for Harvesting Strawberries

Strawberry fruits are products of high commercial and consumption value, and, at the same time, they are difficult to harvest due to their very low mechanical strength and difficulties in identifying them within the bush. Therefore, robots collecting strawberries should be equipped with four subsystems: a video object detection system, a collecting arm, a unit for the reception and possible packaging of the fruit, and a traction system unit. This paper presents a concept for the design and operation of the working section of a harvester for strawberry fruit crops grown in rows or beds, in open fields, and/or under cover. In principle, the working section of the combine should meet parameters comparable with those of manually harvested strawberries (efficiency, quality of harvested fruit) and minimise contamination in the harvested product. In order to meet these requirements, in the presented design concept, it was assumed that these activities would be performed during harvesting with the natural distribution of fruits within the strawberry bush, and the operation of the working head arm maneuvering in the vicinity of the picked fruit, the fruit receiving unit, and other obstacles was developed on the basis of image analysis, initially general, and in detail in the final phase. The paper also discusses the idea of a vision system in which the algorithm used has been positively tested to identify the shapes of objects, and due to the similarity of space, it can be successfully used for the correct location of strawberry fruit.

DETERMINATION OF SCALE COEFFICIENTS FOR SAMPLES OF AUTOCLAVE HEAT-INSULATING AERATED CONCRETE

The results of determining the scale coefficients for autoclave heat-insulating aerat ed concrete of the D450 grade are presented. The scale coefficients with respect to the base sample size 150x150x150 mm with the area of the working section of 225 cm2 are: for samples with the area of the working section of 25 cm2 - 1.29, for samples with the area of the working section of 50 cm2 -1.21, and for samples with the area of the working section of 100 cm2 - 0.82.

Impact of the Weir Slit Location, the Flow Intensity and the Bed Sand on the Scouring Area and Depth at the Dam Upstream

A total of 48 experiments were conducted to investigate the impact of slit weir dimensions and locations on the maximum scour depth and scour area created upstream. The slit weir model was a 110 mm slit opening, and it was installed at the end of the working section in a laboratory flume. The flume was 10.0 m long, 30 cm wide, 30 cm deep, and almost middle. It includes a 2 m working section with a mobile bed with 110 mm in thickness. In the mobile bed, two types of nonuniform sand (with a geometric standard deviation of 1.58 and 1.6) were tested separately. The weir dimensions and location were changed with flow rates. Then dimensions of the slit weir were changed from 60 x 110 mm to 60 x 70 mm (width x height), while the location of the slit weir was changed from the center of the flume to its side. Finally, the flow rates were changed from 2.6 to 8 l/s. The maximum value of scour depth and scour area was recorded 72 mm and 32357 mm2 when the slit height, the flow rate, D50 of the movable bed were 110 mm, 8 l/s, 0.3 mm, respectively.

Investigation of X-band backscattering from wave breaking in a laboratory experiment

<p>The work is concerned with the study of the breaking surface wave effect on the intensity and spectral characteristics of a scattered radar signal in laboratory conditions.</p><p><span>The experiments were carried out on the reconstructed TSWiWaT wind wave flume of the IAP RAS. The channel is 12 m long, the channel cross-section varies from 0.7 x 0.7 m at the entrance to 0.7 x 0.9 m in the working section at a distance of 9 m. The airflow speed on the axis is 3-35 m/s, which corresponds to the values of the wind speed U</span><sub>10</sub><span> of 11-50 m/s.</span></p><p>The wave characteristics in the flume were measured by an array of three wave gauges positioned in the corners of an equal-side triangle with 2.5 cm side, the data sampling rate was 200 Hz. Such a system gives the opportunity to retrieve 3D frequency-wave number spectra of surface waves.</p><p>The airflow parameters were measured using the profiling method. The velocity profiles were measured in the working section using an S-shaped Pitot tube. Microwave measurements were carried out using an X-band coherent Doppler scatterometer with a wavelength of 3.2 cm with sequential reception of linear polarizations.  The absolute value of the radar cross-section (RCS) on the wavy water surface was determined by comparing the scattered signal with the signal reflected from the calibrator with a known value of the RCS - a metal ball with a diameter of 6 cm. The dimensions of the observation cross-section were 40 cm x 40 cm, the incidence angles were 30°, 40°, 50° for the upwind direction, the distance to the target was 3.15 m.</p><p>Two series of experiments were carried out. In the first case, wind waves on the surface of pure deep water, developing under the action of a fan generated wind, were studied. In the second case, a train of three waves was generated at the beginning of the channel, with the fan turned on, in order to simulate shallow water an inclined plate was placed under water in front of the measurement area. As a result, the breaking waves occurred at a fixed point and at weaker winds compared to the first case.</p><p>As a result, an increase in the scattered signal intensity during artificial wave breaking in the case of weak winds was noted. For strong winds, the effect turned out to be insignificant, despite the increased amplitude of the waves under study. The Doppler spectra analysis is also presented.</p><p>This work was supported by the RFBR projects No. 19-05-00249, 19-05-00366.  </p>