The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star forma...

We re-examine past suggestions of a close link between terrestrial climate change and the Sun’s transit of spiral arms in its path through the Milky Way galaxy. These links produced concrete fits, deriving the unknown spiral pattern speed from terrestrial climate correlations. We test these fits against new data on spiral structure based on CO data that does not make simplifying assumptions abo...

Grain selection is an important process in single crystal turbine blades manufacturing. Selector structure is a control factor of grain selection, as well as directional solidification (DS). In this study, the grain selection and structure design of the spiral selector were investigated through experimentation and simulation. A heat transfer model and a 3D microstructure growth model were estab...

Solutions of the 3D nonlinear induction equation for dynamos in spiral galaxies are presented in this paper. Our model includes differential rotation, ambipolar diffusion and, based on small-scale turbulence, eddy diffusivity and the tensorial α–effect underlying magnetic feedback. The nonaxisymmetric radial-azimuthal spiral pattern and the vertical stratification of the galaxy are represented ...

Polishing can be more uniform if the polishing path provides uniform coverage of the surface. It is known that Peano paths can provide uniform coverage of planar surfaces. Peano paths also contain short path segments and turns: (1) all path segments have the same length, (2) path segments are mutually orthogonal at the turns, and (3) path segments and turns are uniformity distributed over the d...

A critical problem in planning sampling paths for autonomous underwater vehicles is correctly balancing two issues. First, obtaining an accurate scalar field estimation and second, efficiently utilizing the stored energy capacity of the sampling vehicle. Adaptive sampling approaches can only provide solutions when real-time and a priori environmental data is available. In this paper we present ...

Gas-liquid separator is an important surface equipment in oilfield development. Improving the separation efficiency of great significance to overall economic benefit oilfield. Spiral a high device that has been widely used, but at present, there are not enough studies on number spiral turns and pitches. In view this problem, paper analyzed gas–liquid separators with different pitches via fluent...

Raptors - falcons, hawks and eagles in this study - such as peregrine falcons (Falco peregrinus) that attack distant prey from high-speed dives face a paradox. Anatomical and behavioral measurements show that raptors of many species must turn their heads approximately 40 degrees to one side to see the prey straight ahead with maximum visual acuity, yet turning the head would presumably slow the...