1,489 research outputs found
Design of a quick-release mechanism for a C-130 aircraft sensor platform
The development of a standardized sensor pallet system for a C-130 aircraft was conceived by the Center for Industrial Research Applications at West Virginia University to assist in counterdrug reconnaissance activities within the United States. The system has been completed and is now being optimized for various uses in addition to counterdrug reconnaissance. It is sought to have the sensor carriers/housings easily interchangeable so that they may be switched in the field by operators rather than in the hangar by technicians. The design parameters were established by the National Guard mission requirements and by the limitations of the C-130 aircraft. These limitations include using Commercial off the Shelf (COTS) and Government off the Shelf (GOTS) components when developing the system that must be universal on all C-130 aircrafts variants B thru H. The following work describes the design process and engineering analysis of this quick-release mechanism design
Eigen-analysis of Inviscid Fluid Structure Interaction (FSI) Systems with Complex Boundary Conditions
A method for extracting the eigenvalues and eigenmodes from complex coupled fluid-structure interaction (FSI) systems is presented. The FSI system under consideration in this case is a one-sided, inviscid flow over a finite-length compliant surface with complex boundary conditions, although the method could be applied to any FSI system. The flow is solved for the inviscid case using a boundary-element method solution of Laplace’s equation, while the finite compliant surface is solved through a finite-difference solution of the one-dimensional beam equation. The crux of the method lies in reducing the coupled fluid and structural equations down to a set of coupled linear differential equations. Standard Krylov subspace projection methods may then be used to determine the eigenvalues of the large system of linear equations. This method is applied to the analysis of hydroelastic FSI systems with complex boundary conditions that would be difficult or otherwise impossible to analyse using standard Galerkin methods. Specifically, the complex cases of inhomogeneous and discontinuous compliant wall properties and arbitrary hinge-joint conditions along the compliant surface are considered
Eigen-analysis of a Fully Viscous Boundary-Layer flow Interacting with a Finite Compliant Surface
A method and preliminary results are presented for the determination of eigenvalues and eigenmodes from fully viscous boundary layer flow interacting with a finite length one-sided compliant wall. This is an extension to the analysis of inviscid flow-structure systems which has been established in previous work. A combination of spectral and finite-difference methods are applied to a linear perturbation form of the full Navier-Stokes equations and one-dimensional beam equation. This yields a system of coupled linear equations that accurately define the spatio-temporal development of linear perturbations to a boundary layer flow over a finite-length compliant surface. Standard Krylov subspace projection methods are used to extract the eigenvalues from this complex system of equations. To date, the analysis of the development of Tollmien-Schlichting (TS) instabilities over a finite compliant surface have relied upon DNS-type results across a narrow (or even singular) spectrum of TS waves. The results from this method have the potential to describe conclusively the role that a finite length compliant surface has in the development of two-dimensional TS instabilities and other FSI instabilities across a broad spectrum
A Cepheid Distance to NGC 4603 in Centaurus
In an attempt to use Cepheid variables to determine the distance to the
Centaurus cluster, we have obtained images of NGC 4603 with the Hubble Space
Telescope on 9 epochs using WFPC2 and the F555W and F814W filters. This galaxy
has been suggested to lie within the ``Cen30'' portion of the cluster and is
the most distant object for which this method has been attempted. Previous
distance estimates for Cen30 have varied significantly and some have presented
disagreements with the peculiar velocity predicted from redshift surveys,
motivating this investigation. Using our observations, we have found 61
candidate Cepheid variable stars; however, a significant fraction of these
candidates are likely to be nonvariable stars whose magnitude measurement
errors happen to fit a Cepheid light curve of significant amplitude for some
choice of period and phase. Through a maximum likelihood technique, we
determine that we have observed 43 +/- 7 real Cepheids and that NGC 4603 has a
distance modulus of 32.61 +0.11/-0.10 (random, 1 sigma) +0.24/-0.25
(systematic, adding in quadrature), corresponding to a distance of 33.3 Mpc.
This is consistent with a number of recent estimates of the distance to NGC
4603 or Cen30 and implies a small peculiar velocity consistent with predictions
from the IRAS 1.2 Jy redshift survey if the galaxy lies in the foreground of
the cluster.Comment: Accepted for publication in the Astrophysical Journal. 17 pages with
17 embedded figures and 3 tables using emulateapj.sty. Additional figures and
images may be obtained from http://astro.berkeley.edu/~marc/n4603
Molecular diagnostics: the changing culture of medical microbiology
Diagnostic molecular biology is arguably the fastest growing area in current laboratory-based medicine. Growth of the so called ‘omics’ technologies has, over the last decade, led to a gradual migration away from the ‘one test, one pathogen’ paradigm, toward multiplex approaches to infectious disease diagnosis, which have led to significant improvements in clinical diagnostics and ultimately improved patient care
Flow-Structure Interaction in the Upper Airway: Motions of a Cantilevered Flexible Plate in Channel Flow with Flexible Walls
The present work seeks to elucidate the flow-structure dynamics of the upper airway so that improved clinical strategies for the alleviation of snoring and sleep apnoea can be developed and applied on an evidence basis. Analogue computational modelling, appropriately related to the anatomically correct system, is used. Hitherto, such modelling has been confined to flow in a rigidchannel to study flutter of the soft palate. Clinical evidence suggests that apneic events can involve combined motions and interactions of the soft palate and flexible walls of the pharynx. We model a flexible cantilevered plate (the soft-palate) mounted in a channel of square cross-section (the pharynx), the downstream side walls of which are flexible to capture deformation in airway collapse. Upstream of the flexible plate is a rigid plate (the hard palate) that spans the channel to permit airflow to be drawn from two inlets (oral and nasal). The commercial FSI software ADINA is used to construct the model and undertake the three-dimensional investigation. Results show that motions of the soft-palate have little effect on the deformation of the side walls. However, the amplitude and frequency of soft-palate vibrations are found to be strongly dependent upon side-wall stiffness and, hence, dynamics
Impact of Online Preparation Modules on Students' Engagement and Interactions in Face-to-Face Fluid Mechanics Laboratories
The transformation of laboratory activities to better embed the development of essential personal attributes and the attainment of specific learning outcomes in the engineering curriculum has been supported by the integration of online preparation modules. Beyond the widely demonstrated effectiveness of multimedia pre-laboratory activities in strengthening students’ engagement and preparedness for the execution of experimental tasks, this study also focuses on the effect of these online modules on student-student and student-instructor interactions in face-to-face fluid mechanics laboratories. Survey data show that students with a mid-level of academic performance were more likely to adopt the new resources but that most students perceived them as a valuable complement to, or replacement for, the traditional instruction sheet. While students’ self-assurance in conducting the laboratory tasks and appreciation of the instructor’s support appear unaffected by the completion of the modules, observations suggest these modules can strengthen students’ autonomy and engagement within their group during the conduct of the laboratory activities. Indeed, the introduction of the modules appears to facilitate a transition of the instructor’s role from directing the laboratory to guiding students in peer-learning
Changing Diagnostic Methods and Increased Detection of Verotoxigenic Escherichia coli, Ireland
The recent paradigm shift in infectious disease diagnosis from culture-based to molecular-based approaches is exemplified in the findings of a national study assessing the detection of verotoxigenic Escherichia coli infections in Ireland. The methodologic changes have been accompanied by a dramatic increase in detections of non-O157 verotoxigenic E. coli serotypes
Plant extract enhances the viability of Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus in probiotic nonfat yogurt
Citation: Michael, M., Phebus, R. K., & Schmidt, K. A. (2015). Plant extract enhances the viability of Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus in probiotic nonfat yogurt. Food Science & Nutrition, 3(1), 48-55. doi:10.1002/fsn3.189A commercial plant extract (prepared from olive, garlic, onion and citrus extracts with sodium acetate (SA) as a carrier) was evaluated to extend the viability of yogurt starter and probiotic bacteria as a means to enhance the shelf life of live and active culture, probiotic nonfat yogurt. Yogurts prepared from three different formulas (0.5% plant extract, 0.25% SA, or no supplement) and cultures (yogurt starter plus Bifidobacterium animalis, Lactobacillus acidophilus, or both probiotics) were assessed weekly during 29 days of storage at 5 degrees C. Supplemented yogurt mixes had greater buffering capacities than non-supplemented yogurt mixes. At the end of storage, Lactobacillus bulgaricus and L. acidophilus counts in supplemented yogurts were greater compared with non-supplemented yogurts. Supplementation did not affect Streptococcus thermophilus and B. animalis counts. Hence the greater buffering capacity of yogurt containing plant extract could enhance the longevity of the probiotics, L. bulgaricus and L. acidophilus, during storage
Remote sensing and geologic studies of the orientale basin region
Both visual and near-infrared spectral observations are combined with multispectral imaging to study the Orientale interior and exterior, the Cruger region, Grimaldi Region, the Schiller-Schickard Region, and the Humorum Region of the Moon. It was concluded that anorthosites occur in the Inner Rook Mountains of Orientale, the inner ring of Grimaldi, and the main ring of Humorum. Imaging spectroscopy shows that the entire eastern Inner Rook Mountains are composed of anorthosites. Orientale ejecta are strikingly like the surface materials in the region where Apollo 16 landed. This similarity indicates similar mineralogy, i.e., noritic anorthosite. Thus, Orientile ejecta is more mafic than the Inner Rook Mountains. This situation is also true for the Nectaris, Humorum, and Gramaldi basins. Isolated areas of the Orientale region show the presence of gabbroic rocks, but, in general, Orientale ejecta are noritic anorthosites, which contain much more low-Ca pyroxene than high-Ca pyroxene. Ancient (pre-Orientale) mare volcanism apparently occurred in several areas of the western limb
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