Acoustic Wind Tunnel Measurements of a Quadcopter in Hover and Forward Flight Conditions

An experimental testing campaign was conducted in the NASA Langley Low Speed Aeroacoustic Wind Tunnel (LSAWT) in order to better understand the acoustic characteristics of a representative quadcopter system in both hover and forward flight conditions. Aerodynamic performance measurements were acquired using a multi-axis load cell to trim the vehicle to desired thrust/lift conditions. Hover acoustic measurements provide evidence of prominent rotor-airframe interaction noise that manifests in the form of high-amplitude harmonics of the fundamental rotor blade passage frequency. Forward flight acoustic measurements of simultaneous rotor operations indicate the presence of strong forward-aft rotor wake interactions that yield increased broadband noise levels relative to cases of individual rotor operation. These results indicate the potential need for modeling complex noise generation mechanisms associated with multirotor and rotor-airframe interactions for vehicles of this class

Art in the Library

The building project currently underway at Old Dominion University Library unexpectedly afforded the library a chance to sponsor a public artwork

Physiological Consequences of Compensatory Growth: A Look at Snake Species Exhibiting Differential Sexual Size Dimorphism

Although many life-history traits are inflexible, extrinsic factors are likely responsible for variation in attributes such as growth rates and ultimately adult body size. Nutritional stress during natal periods, in particular, has significant long-term consequences for adult characteristics. It is thought that poor natal nutrition leads to either the diversion of subsequent energy intake into compensatory growth or delayed maturation. Diversion of energy, to achieve compensation, however does not come without consequence; immune defense is a resource-demanding activity, which can trade- off with traits such as growth. Relatively little is known about the intra- or interspecific variation in immunological capabilities, especially in the context of the effects of stress on immune function. Stress induced levels of glucocorticoids (corticosterone) cause a shift in physiological parameters such that self-maintenance and survival processes are prioritized; by redirecting resources, corticosterone and thus stress especially at chronic levels is generally considered immunosuppressive. I looked at the effects of poor natal nutrition and the potential for compensation on types of immune defense and corticosterone levels in checkered garter and corn snakes, species with different sexual dimorphisms. The effects of accelerated growth rates, following a period of suppressed growth, on immunological function and stress were negligible. This suggests that either snakes are robust animals that can maintain health at low levels of food intake, or that immune function parameters are not downgraded when excess energy is allocated towards compensation (partial or complete). Immune function is thus suggested to be evolutionarily adapted to be maintained during periods of stress

The power, duties and procedures of town finance committees in Massachusetts

Thesis (M.A.)--Boston University, 1948. This item was digitized by the Internet Archive

An Analysis of the Efficacy of the Logistics Composite Model in Estimating Maintenance Manpower Productive Capacity

The Logistics Composite Model (LCOM) is the tool of choice for many MAJCOM\u27s (ACC, USAFE, AFMC) in determining maintenance manpower requirements. The LCOM is a simulation program capable of modeling the manpower, equipment, supplies, and facilities required to conduct aircraft maintenance activities, Manpower studies conducted with the LCOM result in manpower estimates that end up in Unit Manning Documents (UMD) as LCOM earned, authorized positions. This research effort focuses on whether the LCOM can also be used to determine maintenance manpower\u27s current capacity. Three different flying units at Cannon AFB, NM were modeled to determine if the LCOM, when programmed with historical data, would imitate the actual sortie production of those units that were realized during the previous annual flying period (FY2002). Based on the analysis and results presented, the researcher concludes that the LCOM can be a viable tool for this purpose but recommends that a standard set of best practices be developed and implemented by LCOM analysts to standardize the methodology and improve the reliability of results

On the Use of Acoustic Wind Tunnel Data for the Simulation of sUAS Flyover Noise

Acoustic measurements of a small, unmanned aerial system were recently acquired during a ground test campaign. The purposes of the ground test, conducted in the NASA Langley Low Speed Aeroacoustic Wind Tunnel, were to characterize the source noise in terms of its tonal and broadband content, and to identify conditions under which multirotor and rotor-airframe interactions are present. The focus of this work is to assess the effectiveness of using those data for the simulation of flyover noise at a ground observer. The assessment is made at two levels of fidelity using different sets of tools. In the first, 1/3 octave band spectra at a ground receiver will be simulated in a frequency domain approach using the NASA Aircraft NOise Prediction Program. In the second, the pressure time history at a ground receiver is simulated in a time domain approach using the NASA Auralization Framework. Various objective measures are used to verify the simulation process. Acoustic wind tunnel and flight test data are used to gain insight into perceptually important effects

Distance Education Library Services at Old Dominion University

Library resources and services are an essential part of a strong academic distance education program. Students at remote sites must have consistent access to library informational and research materials in order to develop and broaden their understanding of the ideas and research in their disciplines, to bring new ideas to their off-site classrooms, and to acquire and develop their skills in research. These resources are as essential to the remote student as to those on campus. However, students at remote sites may have no facilities comparable to those easily accessed by on campus students. Additionally, many remote site students face obstacles unique to circumstance or location to obtaining research materials. Telecommunication facilities, equipment, site conditions, area libraries, educational background and previous library experience will all be factors in the accessibility of library services and materials to the offsite student. Further, because the remote site student is geographically isolated, he or she must frequently cope with these obstacles individually

An Examination Of Trust In Contemporary American Society

It is hard to imagine a society functioning in the absence of trust. From the smallest incident—crossing the street when the light is green—to the most consequential events—a government fulfilling its pledge to pay Social Security—individuals must be able to rely on individuals and institutions to behave in a reliable and trustworthy manner. When trust is absent, chaos ensues. Of course, trust should not be given blindly; authentic trust needs to be earned and renewed (Fukuyama, 1995; Putnam, 2000)

An Exploration of the Performance and Acoustic Characteristics of UAV-Scale Stacked Rotor Configurations

As interest grows in rotor- and propeller-driven electric vertical takeoff and landing (eVTOL) aircraft for the Urban Air Mobility market, there is a potential for previously studied concepts to reemerge due to the opportunities afforded by novel technologies and operating modes. One such concept is the stacked rotor, which consists of multiple co-rotating rotors positioned co-axially with a small axial offset. The goal of the work presented in this paper is to determine whether stacked rotors offer a compelling advantage for eVTOL aircraft in terms of both performance and acoustic characteristics. Results are presented for new experimental tests and computational modeling of multiple stacked rotor configurations, and comparisons are made with conventional rotor configurations. Testing of thirteen separate configurations each using the same blade shaperevealed a configuration that resulted in an increase in the rotor power loading efficiency by more than 7% and reduced noise by more than 3 dBA when compared with a conventional rotor with all blades located in the same rotational plane

Enhanced Auditory Neuron Survival Following Cell-Based BDNF Treatment in the Deaf Guinea Pig

Exogenous neurotrophin delivery to the deaf cochlea can prevent deafness-induced auditory neuron degeneration, however, we have previously reported that these survival effects are rapidly lost if the treatment stops. In addition, there are concerns that current experimental techniques are not safe enough to be used clinically. Therefore, for such treatments to be clinically transferable, methods of neurotrophin treatment that are safe, biocompatible and can support long-term auditory neuron survival are necessary. Cell transplantation and gene transfer, combined with encapsulation technologies, have the potential to address these issues. This study investigated the survival-promoting effects of encapsulated BDNF over-expressing Schwann cells on auditory neurons in the deaf guinea pig. In comparison to control (empty) capsules, there was significantly greater auditory neuron survival following the cell-based BDNF treatment. Concurrent use of a cochlear implant is expected to result in even greater auditory neuron survival, and provide a clinically relevant method to support auditory neuron survival that may lead to improved speech perception and language outcomes for cochlear implant patients