Figures of Pluto and Charon and their relative motion

The comparative effect of two factors on the translatory motion of the centres of mass of the Pluto-Charon system is investigated. The first important factor is the non-sphericity of the shape and gravitational field of the bodies in the system. The second is the gravitation of the Sun. As a measure of the influence of both factors we use the ratio of the corresponding perturbing acceleration to the main one. The main acceleration is caused by the mutual Newtonian attraction of Pluto and Charon. It has been established that for the first factor this measure is of the order of 10^−6, while for the second factor it is two orders of magnitude smaller. This explains why the Lidov-Kozai effect (despite a large mutual slope of 96 between the planes of the satellite’s orbit around the planet, and the barycentre of the system around the Sun) does not appear. The situation is similar to the case with the satellites of Uranus. As a result, the Pluto-Charon system remains stable at least on a timescale of millions of years. The tidal effect of the Sun on the surface shape of the bodies under study is also estimated. The ratio of the tidal potential of the Sun at a point on the surface of the body to the gravitational potential of the body itself at this point is taken as a measure of impact. It turned out to be of the order of 3 · 10^−12, which is more than six orders less than the influence of rotation and mutual attraction of Pluto and Charon. In fact, the Sun does not affect the figures of the bodies of the system.

Device for Checking Acuteness of Injection Needle Point and Test Methodology

The paper presents a designed device for checking acuteness of injection needle point and development of methodology for conducting corresponding tests. Basic information on disposable injection needles including their purpose, structural elements and requirements for the state of their points. The paper describes a standard method for checking acuteness of injection needle point which is based on measuring maximum force for piercing a high-pressure polyethylene film of a certain thickness by an injection needle during its translatory motion at a given speed. A description is given of the design and operating principle of the developed device that implements this method for checking acuteness of injection needle points. Main provisions of the developed methodology for conducting these tests including sequence and content of actions during their execution have been set out in the paper. Results of the experiments on verification of acuteness in injection needle points of four-diameter confirm practical use validity of the developed device and methodology for conducting corresponding injection needle tests. The obtained oscillograms on changes in the force acting on a needle in the process of polyethylene film piercing are highly informative and that makes it possible to investigate in detail specific features at all stages of the process being studied, including both the stage of film piercing by a test needle and the subsequent stage of removing it from the contact with the film.

OPPORTUNITIES FOR VISUAL EXPERIENCE WHICH MIGHT ALLOW IMPRINTING IN CHICKS RAISED BY BROODY HENS

Chicks raised by a broody hen can see social fellows (mother, sibs) to whom they might attach, only during emergence from under the mother. Chicks raised by a hen showed longest emergences when in broods of 1-2, shortest in broods of 3-4 and longer again in broods > 4. As a result, the first visual experience of any length was on day 2 for broods > 4 and on day 3 for broods of 3-4. Mean duration/chick was 45-50 min in both cases, comparable to times found to give attachment to models. The mother's moving (and often calling) head must be a dominant visual feature for chicks: they most commonly emerge from under the breast and are at once confronted by it. When they emerge from under the wings, the mother turns the head to them, and they then accompany it back to the breast, where they nearly always re-enter. The first experience of the mother in translatory motion on day 5 is so different from this that it probably leads to further learning. Chicks reared in groups without a mother learn to discriminate sibs from strangers. If this occurs in normal broods, it could begin in the group emergences, which are usual on day 3.

Numerical Investigation of Airfoil Dynamic Stall in Simultaneous Harmonic Oscillatory and Translatory Motion

Wind turbine blades are subject to complex flow conditions. For operation in yaw and turbulent inflow, the blade sections appear to execute a motion more complex than a harmonic blade oscillation, which causes dynamic stall. Predictions of dynamic stall caused by simple harmonic oscillation are crucial to efforts in understanding and improving wind turbine performance. Investigation of dynamic stall development caused by a combined oscillatory and translatory motion contributes to better understand blade loading under complex flow conditions. In this paper, numerical predictions of light and deep stall caused by simple oscillatory motion are obtained first. The ability of the numerical solution to predict dynamic stall loads caused by a combined motion is further investigated. The numerical solution is obtained with a factorized, upwind-biased numerical scheme. The turbulent flow region is computed with a one-equation turbulence model. A transition model is used to simulate the transitional flow effects, which play an important role to the overall unsteady flowfield development. The computed results are compared with available experimental data.