2,552 research outputs found
Mach 5 inlet CFD and experimental results
An experimental research program was conducted in the NASA Lewis Research Center 10 x 10 ft supersonic wind tunnel. The 2-D inlet model was designed to study the Mach 3.0 to 5.0 speed range for an over-under turbojet plus ramjet propulsion system. The model was extensively instrumented to provide both analytical code validation data as well as inlet performance information. Support studies for the program include flow field predictions with both 3-D parabolized Navier-Stokes (PNS) and 3-D full Navier-Stokes (FNS) analytical codes. Analytical predictions and experimental results are compared
Remarks on the f_0(400-1200) scalar meson as the dynamically generated chiral partner of the pion
The quark-level linear sigma model is revisited, in particular concerning the
identification of the f_0(400-1200) (or \sigma(600)) scalar meson as the chiral
partner of the pion. We demonstrate the predictive power of the linear sigma
model through the pi-pi and pi-N s-wave scattering lengths, as well as several
electromagnetic, weak, and strong decays of pseudoscalar and vector mesons. The
ease with which the data for these observables are reproduced in the linear
sigma model lends credit to the necessity to include the sigma as a fundamental
q\bar{q} degree of freedom, to be contrasted with approaches like chiral
perturbation theory or the confining NJL model of Shakin and Wang.Comment: 15 pages, plain LaTeX, 3 EPS figure
D^+ \to K^- \p^+ \p^+ : the low-energy sector
An effective chiral lagrangian, which includes scalar
resonances, is used to describe the process D^+ \rar K^- \p^+ \p^+ at
low-energies. Our main result is a set of five -wave amplitudes, suited to
be used in analyses of production data.Comment: Talk given at SCADRON 70 - Workshop on Scalar Mesons and Related
Topics - Lisbon - February 200
A perspective on emerging automotive safety applications, derived from lessons learned through participation in the DARPA Grand Challenges
This paper reports on various aspects of the Intelligent Vehicle Systems (IVS) team's involvement in the recent 2007 DARPA Urban Challenge, wherein our platform, the autonomous “XAV-250,'' competed as one of the 11 finalists qualifying for the event. We provide a candid discussion of the hardware and software design process that led to our team's entry, along with lessons learned at this event and derived from participation in the two previous Grand Challenges. In addition, we give an overview of our vision-, radar-, and LIDAR-based perceptual sensing suite, its fusion with a military-grade inertial navigation package, and the map-based control and planning architectures used leading up to and during the event. The underlying theme of this article is to elucidate how the development of future automotive safety systems can potentially be accelerated by tackling the technological challenges of autonomous ground vehicle robotics. Of interest, we will discuss how a production manufacturing mindset imposes a unique set of constraints upon approaching the problem and how this worked for and against us, given the very compressed timeline of the contests. © 2008 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61244/1/20264_ftp.pd
Being Green and Social Responsibility: Basic Concepts and Multiple Case Studies in Business Excellence
Through a qualitative business case approach, three major manufacturing firms in Pittsburgh, PA were reviewed for their eco-friendly sustainability strategic initiatives and products/services. Undoubtedly, use of green best practices are value adding steps for a company may be initially difficult to justify to spend the time and resources developing such a process. This is especially true when other core business needs are present, such as driving revenue, product development and meeting governmental or consumer expectations. However, green and sustainability initiatives may not be currently dictated needs, but many companies feel strongly that charting such a course would be to their stakeholders’ mutual advantage. As resources are being consumed more rapidly, it is logical to enact steps to ensure the sustainability of such scare resources. The added benefit of lower input needs greatly improves the companies’ stance in their market while also adding to the firms’ overall profitability
Combining brain-computer interfaces and assistive technologies: state-of-the-art and challenges
In recent years, new research has brought the field of EEG-based Brain-Computer Interfacing (BCI) out of its infancy and into a phase of relative maturity through many demonstrated prototypes such as brain-controlled wheelchairs, keyboards, and computer games. With this proof-of-concept phase in the past, the time is now ripe to focus on the development of practical BCI technologies that can be brought out of the lab and into real-world applications. In particular, we focus on the prospect of improving the lives of countless disabled individuals through a combination of BCI technology with existing assistive technologies (AT). In pursuit of more practical BCIs for use outside of the lab, in this paper, we identify four application areas where disabled individuals could greatly benefit from advancements in BCI technology, namely,“Communication and Control”, “Motor Substitution”, “Entertainment”, and “Motor Recovery”. We review the current state of the art and possible future developments, while discussing the main research issues in these four areas. In particular, we expect the most progress in the development of technologies such as hybrid BCI architectures, user-machine adaptation algorithms, the exploitation of users’ mental states for BCI reliability and confidence measures, the incorporation of principles in human-computer interaction (HCI) to improve BCI usability, and the development of novel BCI technology including better EEG devices
Relativistic three-particle scattering equations
We derive a set of relativistic three-particle scattering equations in the
three-particle c.m. frame employing a relativistic three-particle propagator
suggested long ago by Ahmadzadeh and Tjon in the c.m. frame of a two-particle
subsystem. We make the coordinate transformation of this propagator from the
c.m. frame of the two-particle subsystem to the three-particle c.m. frame. We
also point out that some numerical applications of the Ahmadzadeh and Tjon
propagator to the three-nucleon problem use unnecessary nonrelativistic
approximations which do not simplify the computational task, but violate
constraints of relativistic unitarity and/or covariance.Comment: 5pages, text and one ps figure (in revtex) include
Prediction of the Atomization Energy of Molecules Using Coulomb Matrix and Atomic Composition in a Bayesian Regularized Neural Networks
Exact calculation of electronic properties of molecules is a fundamental step
for intelligent and rational compounds and materials design. The intrinsically
graph-like and non-vectorial nature of molecular data generates a unique and
challenging machine learning problem. In this paper we embrace a learning from
scratch approach where the quantum mechanical electronic properties of
molecules are predicted directly from the raw molecular geometry, similar to
some recent works. But, unlike these previous endeavors, our study suggests a
benefit from combining molecular geometry embedded in the Coulomb matrix with
the atomic composition of molecules. Using the new combined features in a
Bayesian regularized neural networks, our results improve well-known results
from the literature on the QM7 dataset from a mean absolute error of 3.51
kcal/mol down to 3.0 kcal/mol.Comment: Under review ICANN 201
Optimizing protection for rear seat occupants: assessing booster performance with realistic belt geometry using the Hybrid III 6YO ATD
A series of sled tests was conducted to examine the performance of booster seats under belt geometries representing the range found in the rear seats of current vehicles. Twelve tests were performed with the standard 6YO Hybrid III ATD and 29 tests were performed with a modified version of the 6YO ATD. The modified dummy has a pelvis with more realistic shape and flesh stiffness, a gel abdomen with biomechanically-based stiffness characteristics, and a custom neoprene jacket. Shoulder belt upper anchorage was set at the FMVSS No. 213 belt anchorage location and 64 mm inboard and outboard from this location. Lap belt anchorage locations were chosen to span the range of lap belt angles permitted under FMVSS 210, using the FMVSS No. 213 belt anchorage locations and forward belt anchorage locations that produce a much steeper lap belt angle. Four booster seats that provide a range of static belt fit were used. The ATDs were positioned using either the standard FMVSS No. 213 seating procedure or an alternate UMTRI procedure that produces postures closer to those of similar-size children.
Kinematic results for the standard and modified dummies under the same test conditions were more similar than expected. The current version of the modified 6YO is less sensitive to lap belt geometry than the prototype version of the dummy. The seating procedure had a greater affect on kinematic results. The UMTRI seating procedure produced greater knee-head excursion differences and less forward torso rotation than the FMVSS No. 213 procedure.
Shifting the shoulder belt upper anchorage 128 mm laterally produced minimal variations in kinematics for a given booster seat/lap belt condition, likely because the belt-routing features of the booster seats limited the differences in static shoulder belt score to less than 10 mm. Moving the lap belt geometry from rearward (shallow angle) to forward (steep angle) produced less desirable kinematics with all booster seats tested. The forward position of the lap belt anchorage allows greater forward translation of the booster and ATD before the belt engages the pelvis. Steeper belt angles are associated with better lap belt fit for children sitting without boosters, so designing rear seat belts for children who sit with and without boosters may involve a performance tradeoff.National Highway Traffic Safety Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/90973/1/102860.pd
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