Pin Wheel Research Articles

Pinwheel

Pinwheel

Stress Analysis of the Pin Wheel in K-H-V Planetary Gears

It is necessary to obtain the stress distribution on the pin wheel in K-H-V planetary gears in order to achieve an optima profile. FEM is effective for the stress analysis, although it is necessary but difficult to give the boundary conditions of the pin wheel for practical use, because there are many loaded points at the same time. In this paper, the boundary conditions are obtained not from simple external forces but from an applied torque. First the displacement distribution in the normal direction of pins is assumed, then the reactions at each contact point are calculated. Then the summation of the products of the reaction forces and arm lengths is made to coincide with the applied torque. Analytical results agree with experimental results qualitatively. Therefore, quantitative agreement will be obtained after careful consideration of boundary conditions. These FEM models of the pin wheel are generated by using some parameters, such as length, radius and angle, instead of numerical dimensions.

Stress analysis of the pin wheel in K-H-V planetary gears.

Stress analysis of the pin wheel in K-H-V planetary gears.

The Scalp “Pinwheel” Flap

The Scalp “Pinwheel” Flap

Techniques for Reconstructing Circular Skin Defects in Dogs

The development of dog‐ears of redundant skin or removal of large areas of additional skin are problems often encountered when closing circular skin defects. Defects 3 cm in diameter were created along the backs of dogs. Eight techniques of reconstruction were evaluated by measuring the area of additional skin removed and length of final suture line and by counting the number of dog‐ears produced. The eight techniques were linear, fusiform, double S, three point, four point, pin wheel, bow tie, and combined V closures. Based on the results of this study, the linear, combined V, and bow tie techniques provide the best closure. In general, the linear technique should be used when skin edges can be apposed without the formation of dog‐ears (e.g., smaller defects). When skin edge apposition results in dog‐ear formation and when there is limited skin for reconstruction surrounding the defect, the combined V technique should be used. When larger dog‐ears form as the skin edges are apposed and when there is an abundance of skin surrounding the defect, the bow tie technique could be considered for closure. One‐half of the bow tie technique can be used to approximate wound edges where one edge is long and curved.

Electron Microscopy and X-Ray Microanalysis of Metal Spheres Formed in a Low Gravity Environment: A Prelude to Skylab

Skylab is America's first manned space station. It offers a unique opportunity to conduct experiments in astronomy, geoscience, the life sciences and engineering. Included in the latter category is the M512 facility for materials processing in space. In addition to other experiments this unit is equipped with a chamber which can be vented to space vacuum and an electron beam heating source capable of melting small metal pendants attached to a rotating pin wheel which may be successively placed at the electron gun focal point. Mechanical fixtures are provided to release the molten body from its support post, if desired, allowing it to solidify under high-vacuum zerogravity conditions.

Microscopia electrônica de inclusões citoplas máticas e alterações celulares associadas ao vírus do mosaico da cenoura

Exames electrono-microscópicos de secções ultrafinas de tecidos foliares de cenoura (Daucus carota L.) e coentro (Coriandrum sativumL.) infetados pelo vírus do mosaico da cenoura (VMC) revelaram a ocorrência de inclusões em forma de bandas densas no citoplasma. Exames mais detalhados dessas bandas revelaram serem elas constituídas pela justaposição de lamelas delgadas (10-15m¼ de espessura), as quais parecem eventualmente desprender-se e formar outros tipos de inclusão, como as de perfil circular e em forma de catavento, comumente associadas à infecção provocada por vírus do grupo Y da batata. Ocasionalmente, partículas do VMC foram observadas nas proximidades dessas inclusões. As dimensões das bandas densas atingiram até 0,l-0,2¼ x 3-4¼, visíveis mesmo em exames ao microscópio convencional. Além da ocorrência dessas inclusões, pôde também ser observada a presença de grande número de vesículas no citoplasma, aparentemente associadas a uma atividade do complexo de Golgi.

Pinwheels in the Heavens

Pinwheels in the Heavens

Impulse Determinations of Rockets by Means of Rotating Systems

Two simple rotating systems have been designed for the determination of the specific impulse of rocket propellants. The pin wheel consists of a bicycle wheel mounted horizontally in a steel frame. A small rocket motor containing the propellant which is to be tested is mounted on the wheel so that the thrust delivered by the rocket accelerates the speed of rotation of the wheel. A photographic record of the rotational speed is then used to calculate the impulse delivered as a function of the time. The rotating bar is operated in a manner similar to that of the pin wheel. The rotating systems have been used for the determination of relative effective gas velocities of a number of double-base rocket powders. Impulse measurements of miniature rockets of the order of 1 pound-second were made. An investigation of the effect of expansion ratio of rocket nozzles on the reduced specific impulse showed good agreement with theoretical calculations.

Gigantic Pinwheel Star Shines with Many Colors

Gigantic Pinwheel Star Shines with Many Colors

On the Evolution of a Rotationally Unstable Star

The fission theory of binary star systems is reexamined and important objections to it are removed. The presence of a magnetic field in the atmosphere of a rotationally unstable star prevents loss of momentum through the loss of atmosphere at the star's equator. By interaction with the atmospheric electric and magnetic fields, the ions are constrained to move systematically in the direction of rotation and add angular momentum to the star proper. Eventually the star divides, and whereas the parent star was radially symmetrical the resulting components are highly asymmetrical and one-half of the star is at a much higher mean temperature than the other half. Tidal couples orient the components just after fission so that the newly exposed faces are oriented inward but are displaced through a small angle. The comparatively high temperatures of the hot faces cause the star to lose mass asymmetrically by radiation or by loss of atmosphere.The lost mass carries off momentum and the reacting forces add both angular momentum and kinetic energy to the massive components; the mechanism being analogous to that of a skyrocket or a pin wheel. When the excess mass lost from the hot face of the components amounts to roughly one five thousandth of the total mass, the added kinetic energy is sufficient to account for the evolution of any type of binary system and for the remarkable differences noted by Sears in his study of the kinetic energies of various types of stars. The relation of such a mechanism to Novae and Cepheid variables is considered. The introduction of reacting forces due to the asymmetrical loss of momentum removes the serious objections that heretofore faces the fission theory and it now seems probable that almost all stars have become rotationally unstable and divided sometime during their life. The magnitude of the radiation reaction forces makes it seem probable that many companion stars have been separated to infinity and that our sun is one star of such a pair. This conclusion has led to a new and more satisfactory theory of the origin of the solar system.

圓弧歯形

In this paper, the form of the tooth profile and the path of contact are determined mathematically by giving the circular arc for the profile of the toothed wheel gearing, and the pin wheel and Matsumura's tooth profiles are derived as the special cases of the gearing. The specific sliding for the profile is studied and is compared with the other tooth profilees, for instance, cycloidal teeth, involute teeth or Matsumura's teeth by some examples.

On the Formation of the Teeth of the Drivers of Pin Wheels

On the Formation of the Teeth of the Drivers of Pin Wheels