Dynamic characterization, monitoring and control of rotating flexible beam-mass structures via piezo-embedded techniques

A variational principle and a finite element discretization technique were used to derive the dynamic equations for a high speed rotating flexible beam-mass system embedded with piezo-electric materials. The dynamic equation thus obtained allows the development of finite element models which accommodate both the original structural element and the piezoelectric element. The solutions of finite element models provide system dynamics needed to design a sensing system. The characterization of gyroscopic effect and damping capacity of smart rotating devices are addressed. Several simulation examples are presented to validate the analytical solution

Aerospace engineering educational program

The principle goal of the educational component of NASA CORE is the creation of aerospace engineering options in the mechanical engineering program at both the undergraduate and graduate levels. To accomplish this goal, a concerted effort during the past year has resulted in detailed plans for the initiation of aerospace options in both the BSME and MSME programs in the fall of 1993. All proposed new courses and the BSME aerospace option curriculum must undergo a lengthy approval process involving two cirriculum oversight committees (School of Engineering and University level) and three levels of general faculty approval. Assuming approval is obtained from all levels, the options will officially take effect in Fall '93. In anticipation of this, certain courses in the proposed curriculum are being offered during the current academic year under special topics headings so that current junior level students may graduate in May '94 under the BSME aerospace option. The proposed undergraduate aerospace option curriculum (along with the regular mechanical engineering curriculum for reference) is attached at the end of this report, and course outlines for the new courses are included in the appendix

Stock Market Interdependence and Trade Relations: A Correlation Test for the U.S. and Its Trading Partners

Based on the well-established trade relations between the U.S. and its major trading partners, this paper examines the robustness of the trade relation hypothesis which, in some recent studies, argues that difference in trade relations among countries can significantly explain difference in the stock market interdependence. The generalized VDC analysis is employed to measure the stock market interdependence, and the correlation test with bootstrap procedure is applied to test the hypothesis. The results indicate that the hypothesis is hardly as a general rule.

OPTIMAL POST-HARVEST GRAINS STORAGE BY RISK AVERSE FARMERS

Most previous research on post-harvest grain storage by farmers has assumed risk-neutral behavior and/or made restrictive assumptions about underlying price probability distributions. In this study we solve the optimal post-harvest storage problem for a risk averse farmer under more general assumptions about underlying price distributions. The resulting model is applied to Michigan corn farmers and results show that, contrary to the sell all-or-nothing risk-neutral rule, risk averse farmers will spread sales out over the storage season. The optimal pattern for sales by Michigan corn farmers is to sell approximately 50% of corn at harvest in November (a risk-reduction strategy) and approximately 40% in May (a return-enhancing strategy).Crop Production/Industries,

LPath+: A First-Order Complete Language for Linguistic Tree Query

PACLIC 19 / Taipei, taiwan / December 1-3, 200

The Study Of The Hydrodynamic Characteristics Of Vertical Upflow Gas-solids Suspension In The Dilute And Dense Phase Regimes

The present experimental work deals with the study of the hydrodynamic characteristics exhibited by a concurrent upflow gas-solids suspension under fully developed flow conditions in the dilute and the dense phase flow regimes. Pressure drop and the mean solids volumetric concentration were measured in vertical transport line of 20 mm inside diameter using sand particles with an average particle diameter of 210 {dollar}\mu{dollar}m. Mean solids concentration of more than 7 percent and solids loading ratios as high as 75 were obtained in the experiments. The mean solids concentration was measured by trapping the particles in a 4.32 m long test section with a set of pneumatic driven quick closing slide valves. The particle size distribution for the solids hold-up was also determined using sieve analysis.;By varying the solids mass flowrates while using the air velocity as the parameter, the dilute phase, \u27dense phase 1\u27, and possibly a third regime--\u27dense phase 2\u27 were observed sequentially. Moreover, unstable operations which lead to the total plugging of the transport line were also experienced at some extreme conditions. The hydrodynamic behaviour such as the mean solids concentration and its average particle diameter, average solids velocity, average slip velocity, average slip velocities of the coarse and the fine fractions, and the pressure drop exhibited in each flow regime was analyzed. Results indicated that both the dilute and the dense phase 1 flow regimes possessed their own distinct hydrodynamic characteristics. However, the difference between those noticed in the dense phase 1 and in the dense phase 2 regimes was subtle. In the course of the experiments, negative solids-wall friction losses were observed at low transport gas velocities when the conveyor was operating in the dense phase regime. The particles in the coarse fraction appeared to travel at a significantly higher speed than the fines in the dilute phase flow. However, both fractions were being carried along at about the same velocities in the dense phase regime.;A power law relationship was developed to correlate the mean solids concentration with the solids mass flowrate and the transport gas velocity for the dilute phase regime. However, the same technique could not be extended to dense phase conveying due to the different solids flow behavior. A flow regime diagram based on the transport gas velocity and the solids mass flowrate was also presented to identify the operating conditions of the observed regimes as well as the limiting solids carrying capacities for the conveying system studied. The overall results point to the conclusion that different methods are required to treat the hydrodynamic characteristics inherent to each flow regime

Controls and guidance research

The objectives of the control group are concentrated on research and education. The control problem of the hypersonic space vehicle represents an important and challenging issue in aerospace engineering. The work described in this report is part of our effort in developing advanced control strategies for such a system. In order to achieve the objectives stated in the NASA-CORE proposal, the tasks were divided among the group based upon their educational expertise. Within the educational component we are offering a Linear Systems and Control course for students in electrical and mechanical engineering. Also, we are proposing a new course in Digital Control Systems with a corresponding laboratory

The Center for Aerospace Research: A NASA Center of Excellence at North Carolina Agricultural and Technical State University

This report documents the efforts and outcomes of our research and educational programs at NASA-CORE in NCA&TSU. The goal of the center was to establish a quality aerospace research base and to develop an educational program to increase the participation of minority faculty and students in the areas of aerospace engineering. The major accomplishments of this center in the first year are summarized in terms of three different areas, namely, the center's research programs area, the center's educational programs area, and the center's management area. In the center's research programs area, we focus on developing capabilities needed to support the development of the aerospace plane and high speed civil transportation system technologies. In the educational programs area, we developed an aerospace engineering option program ready for university approval