Determination of machines working elements speeds optimal correlation when watermelons and cabbages harvesting

In this article, the authors discuss the results of experiments to determine the working bodies moving elements speeds ratio when harvesting watermelons or cabbage heads, having a shape close to a spherical body. It was revealed that the conveyor harvester for watermelons harvesting, equipped with an active roll-in machine, can jam the fruit between the conveyor belt and the roll-in belt, this leads to the fruit damage. To find the minimum allowable damage level (up to 5% according to the agrotechnical requirements), it is necessary that the roll-in tape is made of rubber cloth with a friction coefficient of fт = 0.48, with a ratio of speeds, the limits of change are from 1.0 to 1.3, fruit size is dmin= 15 cm, dmax = 30 cm.

Uses of ultrasonic cleaners in paleontological laboratories

Ultrasonic cleaning is a fast and usually safe method for cleaning many hard objects that are not glued together, and it is thus useful in paleontological laboratories. It is relatively ineffective for cleaning soft materials such as rubber, cloth, and fibers. Ultrasonic cleaning machines use sound waves, or mechanical vibrations, that are above the human hearing range, and operate at frequences up to 55,000 cycles per second. The sound waves are generated by a transducer (Figure 1), which changes high frequency electrical energy to mechanical energy. This mechanical energy, or vibration, is then coupled into the liquid in the cleaning tank. The vibrations cause alternating high and low pressure waves in the liquid. This action forms millions of microscopic bubbles, which expand during low pressure waves and form small cavities. During the high pressure waves, these cavities collapse, or implode, creating a mechanical scrubbinglike action, which loosens dirt on all surfaces in contact with the cleaning solution. This action can take place up to 55,000 times a second, making it seem as though the dirt is being blasted from the surface and cavities of the object being cleaned. Ultrasonic cleaning is effective wherever capillary action will take the solution. Complete cleaning usually requires from 30 seconds to two minutes (Anonymous, 1983).