Impact of Azimuthally Controlled Fluidic Chevrons on Jet Noise

The impact of azimuthally controlled air injection on broadband shock noise and mixing noise for single and dual stream jets was investigated. The single stream experiments focused on noise reduction for low supersonic jet exhausts. Dual stream experiments included high subsonic core and fan conditions and supersonic fan conditions with transonic core conditions. For the dual stream experiments, air was injected into the core stream. Significant reductions in broadband shock noise were achieved in a single jet with an injection mass flow equal to 1.2% of the core mass flow. Injection near the pylon produced greater broadband shock noise reductions than injection at other locations around the nozzle periphery. Air injection into the core stream did not result in broadband shock noise reduction in dual stream jets. Fluidic injection resulted in some mixing noise reductions for both the single and dual stream jets. For subsonic fan and core conditions, the lowest noise levels were obtained when injecting on the side of the nozzle closest to the microphone axis

Assessment of Vessel Density on Non-Contrast Computed Tomography to Detect Basilar Artery Occlusion

Introduction: Basilar artery occlusion (BAO) may be clinically occult due to variable and non-specific symptomatology. We evaluated the qualitative and quantitative determination of a hyperdense basilar artery (HDBA) on non-contrast computed tomography (NCCT) brain for the diagnosis of BAO.Methods: We conducted a case control study of patients with confirmed acute BAO vs a control group of suspected acute stroke patients without BAO. Two EM attending physicians, one third-year EM resident, and one medical student performed qualitative and quantitative assessments for the presence of a HDBA on axial NCCT images. Our primary outcome measures were sensitivity and specificity for BAO. Our secondary outcomes were inter-rater and intra-rater reliability of the qualitative and quantitative assessments.Results: We included 60 BAO and 65 control patients in our analysis. Qualitative assessment of the hyperdense basilar artery sign was poorly sensitive (54%–72%) and specific (55%–89%). Quantitative measurement improved the specificity of hyperdense basilar artery assessment for diagnosing BAO, with a threshold of 61.0–63.8 Hounsfield units demonstrating relatively high specificity of 85%–94%. There was moderate inter-rater agreement for the qualitative assessment of HDBA (Fleiss’ kappa statistic 0.508, 95% confidence interval: 0.435–0.581). Agreement improved for quantitative assessments, but still fell in the moderate range (Shrout-Fleiss intraclass correlation coefficient: 0.635). Intra-rater reliability for the quantitative assessments of the two attending physician reviewers demonstrated substantial consistency.Conclusion: Our results highlight the importance of carefully examining basilar artery density when interpreting the NCCT of patients with altered consciousness or other signs and symptoms concerning for an acute basilar artery occlusion. If the Hounsfield unit density of the basilar artery exceeds 61 Hounsfield units, BAO should be highly suspected

ECLSS advanced automation preliminary requirements

A description of the total Environmental Control and Life Support System (ECLSS) is presented. The description of the hardware is given in a top down format, the lowest level of which is a functional description of each candidate implementation. For each candidate implementation, both its advantages and disadvantages are presented. From this knowledge, it was suggested where expert systems could be used in the diagnosis and control of specific portions of the ECLSS. A process to determine if expert systems are applicable and how to select the expert system is also presented. The consideration of possible problems or inconsistencies in the knowledge or workings in the subsystems is described

A diagnostic prototype of the potable water subsystem of the Space Station Freedom ECLSS

In analyzing the baseline Environmental Control and Life Support System (ECLSS) command and control architecture, various processes are found which would be enhanced by the use of knowledge based system methods of implementation. The most suitable process for prototyping using rule based methods are documented, while domain knowledge resources and other practical considerations are examined. Requirements for a prototype rule based software system are documented. These requirements reflect Space Station Freedom ECLSS software and hardware development efforts, and knowledge based system requirements. A quick prototype knowledge based system environment is researched and developed

The Signature of Primordial Grain Growth in the Polarized Light of the AU Mic Debris Disk

We have used the Hubble Space Telescope/ACS coronagraph to make polarization maps of the AU Mic debris disk. The fractional linear polarization rises monotonically from about 0.05 to 0.4 between 20 and 80 AU. The polarization is perpendicular to the disk, indicating that the scattered light originates from micron sized grains in an optically thin disk. Disk models, which simultaneously fit the surface brightness and polarization, show that the inner disk (< 40-50 AU) is depleted of micron-sized dust by a factor of more than 300, which means that the disk is collision dominated. The grains have high maximum linear polarization and strong forward scattering. Spherical grains composed of conventional materials cannot reproduce these optical properties. A Mie/Maxwell-Garnett analysis implicates highly porous (91-94%) particles. In the inner Solar System, porous particles form in cometary dust, where the sublimation of ices leaves a "bird's nest" of refractory organic and silicate material. In AU Mic, the grain porosity may be primordial, because the dust "birth ring" lies beyond the ice sublimation point. The observed porosities span the range of values implied by laboratory studies of particle coagulation by ballistic cluster-cluster aggregation. To avoid compactification, the upper size limit for the parent bodies is in the decimeter range, in agreement with theoretical predictions based on collisional lifetime arguments. Consequently, AU Mic may exhibit the signature of the primordial agglomeration process whereby interstellar grains first assembled to form macroscopic objects.Comment: 12 pages, 8 figures, ApJ, in pres

Migrating learning management systems: A case of a large public university

In the past 20 years, institutions of higher education have made major investments in Learning Management Systems (LMSs). As institutions have integrated the LMS into campus culture, the potential of migrating to not only an upgraded version of the LMS, but also an entirely different LMS, has become a reality. This qualitative research study examines the perspectives of five stakeholders involved with the migration of an LMS at a major research institution in the southeastern United States. Using Lewin’s (1947) Change Management Model and Enterprise Resource Planning (ERP) Model as analogies, this research seeks to understand the role and responsibilities of the various stakeholders, their decision-making, and the implications of the decisions on the migration process. Using Glaser and Strauss’s (1967) constant comparative method and Charmaz’s (2006) work related to grounded theory, four major categories emerged from our data: time as a catalyst for change, power of communication, compatibility of technologies, and faith in the system. The categories contribute to a preliminary model that may assist other institutions as they consider whether to migrate LMSs

Student Internships in Extension: Strategies for Success for the Agent and the Student

The Extension internship provides a valuable learning experience for the agent and the intern. The intern receives a lesson in real-world-learning ; for many agents, supervising an intern is an opportunity to update their knowledge and skills. Too often the intern and the agent are not a good match, leaving both parties dissatisfied and disappointed. This article offers three perspectives of the internship experience, that of the agent, the intern, and campus supervisor. We offer suggestions for strategies agents can use to enhance the internship experience for all involved and remind the reader that internships are an excellent recruiting tool

B789: A Breakeven Analysis of Two Rural Health Maintenance Organization Models

This report uses breakeven analysis to assess the financial feasibility of two health maintenance organization (HMO) models which have received considerable support from health-care professionals as potentially viable organizations in rural areas. The two models analyzed, the individual practice association and satellite clinic, represent quite different organizational and financial structures. Enrollment levels required for each HMO model to attain financial viability for specified premium rates are calculated. In addition, the effects of varying key health-care utilization rates on an HMO\u27s financial position are assessed. This information should be of interest to extension agents and others who are working with groups contemplating a variety of health initiatives.https://digitalcommons.library.umaine.edu/aes_bulletin/1067/thumbnail.jp

Microthia, Holocryphia and Ursicollum, three new genera on Eucalyptus and Coccoloba for fungi previously known as Cryphonectria

Cryphonectria havanensis is a fungus associated with Eucalyptus species in Cuba and Florida (U.S.A.). Until recently, there have been no living cultures of C. havanensis and it has thus not been possible to assess its taxonomic status. Isolates thought to represent this fungus have, however, emerged from surveys of Eucalyptus in Mexico and Hawaii (U.S.A.). Results of this study showed that these isolates represent C. havanensis but reside in a genus distinct from Cryphonectria sensu stricto, which is described here as Microthia. Isolates of an unidentified fungus occurring on Myrica faya in the Azores and Madeira also grouped in Microthia and were identical to other M. havanensis isolates. Cryphonectria coccolobae, a fungus occurring on sea grape (Coccoloba uvifera) in Bermuda and Florida, was found to be morphologically identical to Microthia and is transferred to this genus, but as a distinct species. Surveys for M. coccolobae on sea grape in Florida, yielded a second diaporthalean fungus from this host. This fungus is morphologically and phylogenetically distinct from M. coccolobae and other closely related taxa and is described as Ursicollum fallax gen. et sp. nov. Phylogenetic analyses in this study have also shown that isolates of C. eucalypti, a pathogen of Eucalyptus in South Africa and Australia, group in a clade separate from all other groups including that representing Cryphonectria sensu stricto. This difference is supported by the fact that Cryphonectria eucalypti has ascospore septation different to that of all other Cryphonectria species. A new genus, Holocryphia, is thus erected for C. eucalypti

Electric Motor Noise from Small Quadcopters

The increased interest in electric motors for propulsion systems has driven interest in quantifying the contribution of electric motor noise to the overall sound levels and possible human annoyance of the propulsion system. This work presents acoustic measurements of electric motors used for small quadcopters to quantify the sound produced by a number of outrunning motors with different types of controllers. Results are presented for loaded and unloaded motors as installed and uninstalled configurations. Motor resonance frequencies were measured and computed. Current probe measurements showed that the supply current from the controllers contained significant harmonic content for the conventional and sinewave controllers. Acoustic results showed motor noise is typically radiated at frequencies near the mode 2 vibration frequency at roughly 5000 Hz. Electric motor noise was evident in the spectra produced by many of the motor-controller combinations for motors loaded with propellers with levels often greater than those for the motor alone due to increase in the stator magnetic flux density with increased current. An installed configuration produced increases in acoustic radiation over that of the uninstalled motor in a frequency range near the mode 1 vibration frequency near 1200 Hz. A companion paper (Part I - Acoustic Measurements), focuses on source identification using a phased array and directivity characteristics for a baseline configuration