A theoretical and flight test study of pressure fluctuations under a turbulent boundary layer. Part 2: Flight test study

The study of pressure fluctuations under a turbulent boundary layer was undertaken with the objective of extending previous work to lower frequencies. Wind tunnel and flight test measurements are invalid at low frequencies because of extraneous acoustic noises and free stream turbulence. A glider was instrumented and used as a test bed to carry microphones into a smooth flow free of acoustic noise. Hodgson had previously measured the spectrum of boundary layer noise on a glider wing. These tests showed a drop off at low frequencies that could not be reproduced in any other facility. The measurements were made on the forward fuselage of a glider where the boundary layer could develop naturally and have some length in a zero pressure gradient before the measurements were made. Two different sets of measurements were made

Effects of elevated atmospheric carbon dioxide concentrations on water and acid requirements of soybeans grown in a recirculating hydroponic system

Establishing mass budgets of various crop needs, i.e. water and nutrients, in different environments is essential for the Controlled Ecological Life Support System (CELSS). The effects of CO2 (500 and 1000 umol mol (exp -1)) on water and acid use (for pH control) by soybeans in a recirculating hydroponic system were examined. Plants of cvs. McCall and Pixie were grown for 90 days using the nutrient film technique (NFT) and a nitrate based nutrient solution. System acid use for both CO2 levels peaked near 4 weeks during a phase of rapid vegetative growth, but acid use decreased more rapidly under 500 compared to 1000 umol mol (exp GR) CO2. Total system water use by 500 and 1000 umol mol (exp -1) plants was similar, leaving off at 5 weeks and declining as plants senesced (ca. 9 weeks). However, single leaf transpiration rates were consistently lower at 1000 umol mol (exp -1). The data suggest that high CO2 concentrations increase system acid (and nutrient) use because of increased vegetative growth, which in turn negates the benefit of reduced water use (lower transpiration rates) per unit leaf area

Challenges for Global Learners: A Qualitative Study of the Concerns and Difficulties of International Students

The authors in this study seek to inform academia about international students’ experiences and challenges while attending universities in Small Town USA. Despite their eagerness to study in the United States (U.S.), international students are faced with setbacks that many universities fail to recognize or realize. The researchers conducted in-depth interviews with a purposive sample of students using questions based on information from the literature and an initial survey. The themes that emerged from the data analysis were language, jobs/finances, transportation, assimilation, religious interactions, and identity. Findings emphasize the imperative to understand the challenges these students face as they continue their educational journeys in the United States

Cleaning Process Development for Metallic Additively Manufactured Parts

Additive Manufacturing of metallic components for aerospace applications offers many advantages over traditional manufacturing techniques. As a new technology, many aspects of its widespread utilization remain open to investigation. Among these are the cleaning processes that can be used for post finishing of parts and measurements to verify effectiveness of the cleaning processes. Many cleaning and drying processes and measurement methods that have been used for parts manufactured using conventional techniques are candidates that may be considered for cleaning and verification of additively manufactured parts. Among these are vapor degreasing, ultrasonic immersion and spray cleaning, followed by hot air drying, vacuum baking and solvent displacement drying. Differences in porosity, density, and surface finish of additively manufactured versus conventionally manufactured parts may introduce new considerations in the selection of cleaning and drying processes or the method used to verify their effectiveness. This presentation will review the relative strengths and weaknesses of different candidate cleaning and drying processes as they may apply to additively manufactured metal parts for aerospace applications. An ultrasonic cleaning technique for exploring the cleanability of parts will be presented along with an example using additively manufactured Inconel 718 test specimens to illustrate its use. The data analysis shows that this ultrasonic cleaning approach results in a well-behaved ultrasonic cleaning/extraction behavior. That is, it does not show signs of accelerated cavitation erosion of the base material, which was later confirmed by neutron imaging. In addition, the analysis indicated that complete cleaning would be achieved by ultrasonic immersion cleaning at approximately 5 minutes, which was verified by subsequent cleaning of additional parts

Future Fuel Scenarios and Their Potential Impact to Aviation

In recent years fuel prices have been growing at a rapid pace. Current conservative projections predict that this is only a function of the natural volatility of oil prices, similar to the oil price spikes experienced in the 1970s. However, there is growing concern among analysts that the current price increases may not only be permanent, but that prices may continue to increase into the future before settling down at a much higher level than today. At high enough fuel prices, the aircraft industry would become very sensitive to fuel price. In this paper, the likelihood of fuel price increase is considered in three different price increase scenarios: "low," "medium," and "high." The impact of these scenarios on the aviation industry and alternatives are also addressed

Complexity of Fetal Movement Detection Using a Single Doppler Ultrasound Transducer

The objective of this paper is to discuss the complexity of fetal movement detection encountered during development and implementation of an automated single Doppler ultrasonic transducer based instrument. The single transducer instrument was intended to better quantify the duration, velocity, and magnitude of fetal movements. A Corometrics Model 116 fetal heart rate monitor was modified, and a fetal movement detection algorithm (Russell Algorithm) was developed to detect fetal movements on one and two (data fusion) transducers. A Hewlett-Packard (HP) M-1350-A fetal monitor and the Russell Algorithm were used to detect and record fetal movements concurrently on sixty patients between the gestation ages of31 to 41 weeks. Using a computer-controlled SVHS PC-VCR, the instrumental detection of fetal movements was time-linked with real-time video ultrasound. This allowed the fetal movements to be scored by expert examiners on a second-per-second basis. A total of 52,478 seconds of fetal movements was scored using this system. Neither system could accurately define the entire duration, velocity, or magnitude of the fetal movements as detected by real-time ultrasound. The complexity of detecting fetal movements using only one transducer has many shortcomings, such as: the amplitude of the returning Doppler signal, the small area of the fetus monitored by a single transducer, the position of the fetus, the type and variety of fetal movements, and material size and shape

National Survey on Leadership Capacity and Scaling-up of PBIS Implementation

This study examined State Education Agency (SEA) efforts to scale up Positive Behavioral Interventions and Supports (PBIS) implementation across K-12 public schools within the United States of America. The researcher used archival data to determine percentages of school within each state currently implementing PBIS and a survey method to determine each state’s status regarding standards of PBIS implementation and variables of leadership capacity. The survey instrument was the State PBIS Implementation and Leadership Survey (SPILS). The participants were SEAs from each state and the District of Columbia, as represented by PBIS Coordinators or other designated PBIS professionals. The purpose of this study was to determine which states could be considered taking PBIS to scale as evidenced by \u3e 60% of the schools implementing PBIS and scores of 80% or higher on the standard of PBIS implementation and the variables of leadership capacity prongs of the SPILS form

An Autoethnography of Culturally Relevant Leadership as Moral Practice: Lived Experiences through a Scholar-Practitioner Lens

In this autoethnography, I am concerned with cultural relevance as an experience of a scholar-practitioner educational leader. I question my own cultural competence as a teacher and school principal. Turning a reflective gaze on my lived experiences as an educator creates a space in which I attempt to make meaning of the phenomenon of culturally relevant practices in the field of education. As an act of pedagogical and personal meaning-making, this autoethnographic work centers on the value of cultural relevance as informed by scholarly practice