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.

Numerical Investigation of Heat Transfer Enhancement in a Slot Channel Induced by a Piezoelectric Fan

Abstract: Heat transfer enhancement in an isothermal slot channel due to vortices shedding from a vibrating piezoelectric fan is numerically investigated at $\pmb{Re}=\mathbf{500}$. The numerical simulations are performed for the dimensionless frequency $\pmb{Sr}$ and dimensionless amplitude $\pmb{A}$ in the ranges of 0 ~ 1 and 0 ~ 0.25, respectively. Effects of Prandtl number $(\mathbf{0.1}\leq\pmb{Pr}\leq\mathbf{10})$ on the heat transfer enhancement for different fluids are also discussed. The results show that vibration of the piezoelectric fan can significantly enhance the heat transfer performance of the downstream walls of the fan. A critical dimensionless amplitude value of 0.1 is found for the heat transfer enhancement of the fan. Moreover, the benefits of fan vibration in enhancement of wall heat transfer are found to be very sensitive to $\pmb{Pr}$. The maximum heat transfer enhancement ratio of 41.6% is obtained when $\pmb{Pr}$ is approximately equal to 1.

Limited capacity of working memory in unihemispheric random walks implies conceivable slow dispersal.

Abstract: Phenomenologically inspired by dolphins’ unihemispheric sleep, we introduce a minimal model for random walks with physiological memory. The physiological memory consists of long-term memory which includes unconscious implicit memory and conscious explicit memory, and working memory which serves as a multi-component system for integrating, manipulating and managing short-term storage. The model assumes that the sleeping state allows retrievals of episodic objects merely from the episodic buffer where these memory objects are invoked corresponding to the ambient objects and are thus object-oriented, together with intermittent but increasing use of implicit memory in which decisions are unconsciously picked up from historical time series. The process of memory decay and forgetting is constructed in the episodic buffer. The walker’s risk attitude, as a product of physiological heuristics according to the performance of objected-oriented decisions, is imposed on implicit memory. The analytical results of unihemispheric random walks with the mixture of object-oriented and time-oriented memory, as well as the long-time behavior which tends to the use of implicit memory, are provided, indicating the common sense that a conservative risk attitude is inclinable to slow movement.

Aircraft that fly backwards? The application of forward swept wings

Abstract: It was recognised over 40 years ago that sweeping the wing of an aircraft could be used to offset the effects of compressibility. However, by no means all of the earlier swept-back wing aircraft used sweep for performance reasons. Some, such as the Horten tailless gliders built in Germany, had swept back wings to ensure necessary longitudinal stability. Likewise the Messerschmitt Me163 rocket interceptor employed a swept back wing as an essential feature of its layout but it operated at a sufficiently high Mach number for the beneficial aerodynamic effects of sweep to be of value. From the compressibility point of view, the wing may be either swept back or swept forward, and the idea of forward sweep was incorporated in the Junkers Ju287 jet propelled bomber (Fig. 1). The 18 degrees forward sweep enabled the wing-fuselage intersection to be positioned behind the deep bomb-bay and thus avoided a difficult structural cut-out problem. A more elegant solution to the same difficulty was the ‘crescent’ swept-back wing layout for the Handley-Page Victor bomber.

Chapter 8 – statistical methods

Abstract: Publisher Summary This chapter discusses the statistical methods of all measurement techniques. Probability is concerned with the measured outcomes of experiments that are individually unpredictable. The general shape of a probability density diagram indicates a feature known as the probability distribution of which there is an infinite variety. However, certain types of probability distribution arise from theoretical concepts, and many practical situations in nature can be regarded as approximating to one or other of these special distributions. A basic form is the binomial distribution that is associated with events having only a binary or go-no-go outcome. Auto-correlation analysis is seen to describe the variability of a function. However, when an experiment results in the production of an irregular waveform it is not unreasonable to try to break it down in terms of a Fourier series. If the waveform is truly random noise it is essentially aperiodic, and no fundamental frequency can be present.