Vaughn College of Aeronautics and Technology

About: Vaughn College of Aeronautics and Technology is a education organization based out in New York, New York, United States. It is known for research contribution in the topics: Gravitational microlensing & Planetary system. The organization has 727 authors who have published 708 publications receiving 14082 citations. The organization is also known as: College of Aeronautics.

Creep in oriented thermoplastics

Abstract: Sheets of oriented low-density polyethylene possessing transverse symmetry were prepared by simple tensile drawing at room temperature. The degree of anisotropy was varied by varying the draw ratio. Classic elasticity theory shows that five constants are necessary to characterize the deformation behavior of an elastic material possessing such symmetry. The time-dependent equivalents of these constants have been determined from the simultaneous measurement of longitudinal and lateral strain during tensile creep of specimens cut at 0, 45, and 90 deg to the draw direction. Special creep apparatus, able to handle small, flexible specimens, was developed for this study. The shear compliance obtained from the tensile creep studies was in good agreement with the value obtained from torsional creep measurements on a 0-deg specimen, for the entire range of draw ratios. The contraction measurements have been used to provide additional evidence for deformation mechanisms suggested by the longitudinal strain...

Comparison of Two Optimal Guidance Methods for the Long-Distance Orbital Pursuit-Evasion Game

Abstract: The orbital pursuit-evasion game (OPE) is a topic of research that has been attracting increasing attention from scholars. However, most works based on the relative dynamics under a short-distance assumption is not applicable when the distance between two spacecrafts is too large. Accordingly, there should be two phases in the OPE, a long-distance OPE (LDOPE) as well as a short-distance one. This article concerns on the optimal guidance problem for the LDOPE. Two different models are introduced in this article to formulate the LDOPE, namely, the Cartesian model, and the spherical model. Then, to overcome the unacceptable solution computation time of traditional algorithms, such as the differential evolution (DE), a well-designed algorithm called “mixed global-local optimization strategy” (MGLOS), which consists of the global optimization phase, and the local optimization phase, is introduced in this article. The MGLOS is nearly two orders of magnitude more efficient than the DE. Moreover, simulations under different initial conditions demonstrate the robustness of the algorithm, and the accuracy, and efficiency of the Cartesian, and spherical models, respectively. Finally, the robustness of two models is analyzed by Monte Carlo simulation, which provides a quantified way to make a choice between two models depending on the measurement accuracy, and permitted maximum error.

The electromagnetic fields of moving dipoles

Abstract: Recent papers by J. R. Ellis and the author contain formulae for the fields of moving dipoles which are expressed in rather different forms in the two papers, and it appears that the author's results are more general than Ellis's. Here, the results are re-derived from a consideration of the Hertzian six-vector potential for a distribution of moving dipoles, and a comparison is made with the previous forms. It is found that Ellis's results are essentially as general as the author's. The expressions for the potentials and the field tensors are treated as weak functions in Temple's sense, and very few restrictions have to be imposed on the dipole moments and velocities, which may be expressed either as functions of coordinate time or as functions of proper-time.