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.

Some examples of the application of the Beecham-Titchener-Simpson (BTS) method to autonomous systems

Abstract: It is noted that the averaging technique of Beecham and Titchener, for obtaining approximate solutions to nonlinear, ordinary, differential equations, is not widely known or used. In its extended form, as given by Simpson and Ross it appears to offer a unified and useful approach to the solution of many dynamical and other problems. The present paper sets out to describe and discuss, through the medium of a collection of examples, the Beecham-Titchener-Simpson (BTS) method in an effort to encourage its more widespread use.

Progress and problems in gas-turbine combustion

Abstract: In recent years the accumulation of reliable experimental data confirming the previously derived relationships between combustion-chamber dimensions; specific pressure loss; and the operating conditions of pressure, temperature, and velocity, has led to the formulation of design rules and to a much clearer appreciation of the most promising lines of research. At the present time, it is difficult to envisage areas in which fundamental research can make an effective contribution to combustion-chamber development, at least in the foreseeable future, but there is ample scope for applied research on ignition, fuel-injection methods, fluid-dynamic and heat-transfer processes, and modeling technics. Although research on these topics is unlikely to produce significant reductions in chamber size and pressure loss, it should lead to worthwhile improvements in terms of reduced size and weight of ignition equipment, elimination of exhaust smoke, longer flametube life, and to an outlet-temperature profile that is less sensitive to variations in engine operating conditions.

GARCH based degradation modeling of solder joint under vibration loading

Abstract: The degradation behavior of the solder joint under constant vibration loading is discussed, the voltage value at both sides of the solder joint is taken as the degradation characteristic. Considering the heteroskedasticity of characteristic signal under the vibration loading, the general time series model cannot describe heteroskedasticity, a Generalized Autoregressive Conditional Heteroskedastic model (GARCH) is proposed. Firstly, the upper and lower quantiles of the voltage signal are extracted. The failure time is determined by using the upper quantile and the degradation process is analyzed by the lower quantile. Secondly, the Auto-Regressive(AR) is built as the regressive basic model. Thirdly, a GARCH(1,1) model is proposed, which is tested by the Autoregressive Conditional Heteroskedastic (ARCH) method, the parameters of the model is estimated by the Maximum Likelihood algorithm. Finally, the performance of the presented GARCH based degradation model is examined by real data from experiment, which is compared with the classical AR model according to Akaike Information Criterion(AIC). The results suggest that GARCH(1,1) is superior to AR model, presented a theoretical foundation for further study about the degradation modeling of solder joint under vibration loading.

Compressions of magnetorheological fluids under instantaneous magnetic field and constant area.

Abstract: Compressions of magnetorheological (MR) fluids have been carried out under instantaneous magnetic fields. The yield strength of the MR fluid in compressive mode has been derived by assuming that it was a transformed shear flow in Bi-visous model. The compressive stresses have experimentally studied under different magnetic fields, different initial gap distances and different compressive velocities. The nominal yield shear stresses of the compressed MR fluid under different influential factors have been calculated. The compressive stress increased in a power law as the applied magnetic field increased, while it decreased as the initial gap distance and the compressive velocity increased. With the increase of magnetic field, the difference between the nominal yield shear stress curves increased, and the exponents of the power law increased with the increase of the magnetic field strengths. A larger initial gap distance and a lower compressive velocity resulted in a higher nominal yield shear stress under the same instantaneous magnetic field. The achieved results of the nominal yield shear stress with magnetic field seemed to deviate from the prediction of dipole model, and the chain structure aggregation effect, the sealing effect and the friction effect by compression should be considered.