Finite element thermo-viscoplastic analysis of aerospace structures

The time-dependent thermo-viscoplastic response of aerospace structures subjected to intense aerothermal loads is predicted using the finite-element method. The finite-element analysis uses the Bodner-Partom unified viscoplastic constitutive relations to determine rate-dependent nonlinear material behavior. The methodology is verified by comparison with experimental data and other numerical results for a uniaxially-loaded bar. The method is then used (1) to predict the structural response of a rectangular plate subjected to line heating along a centerline, and (2) to predict the thermal-structural response of a convectively-cooled engine cowl leading edge subjected to aerodynamic shock-shock interference heating. Compared to linear elastic analysis, the viscoplastic analysis results in lower peak stresses and regions of plastic deformations

All My Circuits: Using Multiple Electrodes to Understand Functioning Neural Networks

Much of the work in systems neuroscience thus far has focused on the brain's parts studied individually. The past 20 years has seen the advent, rise, and application of multiple-electrode technology. This allows the study of the activity of many neurons simultaneously, which in turn has provided insight into how different neuron populations interact and collaborate to produce thought and action

Some Day : When The War Is O\u27er

https://digitalcommons.library.umaine.edu/mmb-vp/5423/thumbnail.jp

USCID fourth international conference

Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.While rice is produced in some parts of the world in an upland, rainfed culture, almost all US-produced rice is grown with flood irrigation. In the dry-seeding system commonly used in the midsouthern US, the crop is usually flooded at approximately the V-4 (early tillering) growth stage and a continuous flood is maintained until after heading. The total amount of water used in rice production is quite large, and soil, fertilizers, and pesticides can be carried in the runoff from agricultural fields. Flood depth affects most aspects of flooded rice production, and remote monitoring of the flood depth could be quite valuable to many producers. The objective of this research is to develop and test a system for monitoring water depths in rice fields and alerting the producer so that less labor and energy is required to efficiently manage flood-irrigated rice. A prototype monitoring station was designed to measure water depth in a flooded rice field and transmit the information over a wireless link. A similar sensor and circuit performed satisfactorily in a raingage in 2006. In 2007, prototype monitoring stations will be installed in production rice fields. Concurrently with sensor durability testing, tests will be conducted to determine the limits of the wireless communication system. With daily reports of the water status in each paddy, field visits can be reduced. Over-pumping should be minimized by allowing better scheduling of field visits to stop the pump, and future systems should work with automatic pump control systems to stop the pump before runoff occurs

Status report on a natural laminar-flow nacelle flight experiment

The natural laminar flow (NLF) nacelle experiment is part of a drag reduction production program, and has the dual objectives of studying the extent of NLF on full scale nacelles in a flight environment and the effect of acoustic disturbance on the location of transition on the nacelle surface. The experiment is being conducted in two phases: (1) an NLF fairing was flown on a full scale Citation nacelle to develop the experiment technique and establish feasibility; (2) full scale, flow through, NLF nacelles located below the right wing of an experimental NASA OV-1 aircraft are evaluated. The measurements of most interest are the static pressure distribution and transition location on the nacelle surface, and the fluctuating pressure levels associated with the noise sources. Data are collected in combinations of acoustic frequencies and sound pressure levels. The results of phase 2 tests to date indicate that on shape GE2, natural laminar flow was maintained as far aft as the afterbody joint at 50 percent of the nacelle length. An aft facing step at this joint caused premature transition at this station. No change was observed in the transition pattern when the noise sources were operated

Change of Interest as a Function of Shift in Curricular Orientation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67119/2/10.1177_001316445301300213.pd

NASA-UVA Light Aerospace Alloy and Structures Technology Program: LA(2)ST

The NASA-UVA Light Aerospace Alloy and Structures Technology (LA(2)ST) Program continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, Civil Engineering and Applied Mechanics, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. We report on progress achieved between July 1 and December 31, 1992. The objective of the LA(2)ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement advances; and critically, a pool of educated graduate students for aerospace technologies

Comparative landscape dynamics of two anuran species: climate‐driven interaction of local and regional processes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117162/1/ecm2009793503.pd

NASA-UVA light aerospace alloy and structures technology program

The report on progress achieved in accomplishing of the NASA-UVA Light Aerospace Alloy and Structures Technology Program is presented. The objective is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys and associated thermal gradient structures in close collaboration with researchers. The efforts will produce basic understanding of material behavior, new monolithic and composite alloys, processing methods, solid and fluid mechanics analyses, measurement advances, and a pool of educated graduate students. The presented accomplishments include: research on corrosion fatigue of Al-Li-Cu alloy 2090; research on the strengthening effect of small In additions to Al-Li-Cu alloys; research on localized corrosion of Al-Li alloys; research on stress corrosion cracking of Al-Li-Cu alloys; research on fiber-matrix reaction studies (Ti-1100 and Ti-15-3 matrices containing SCS-6, SCS-9, and SCS-10 fibers); and research on methods for quantifying non-random particle distribution in materials that has led to generation of a set of computer programs that can detect and characterize clusters in particles