Aircraft wing trailing-edge noise

The mechanism and sound pressure level of the trailing-edge noise for two-dimensional turbulent boundary layer flow was examined. Experiment is compared with current theory. A NACA 0012 airfoil of 0.61 m chord and 0.46 m span was immersed in the laminar flow of a low turbulence open jet. A 2.54 cm width roughness strip was placed at 15 percent chord from the leading edge on both sides of the airfoil as a boundary layer trip so that two separate but statistically equivalent turbulent boundary layers were formed. Tests were performed with several trailing-edge geometries with the upstream velocity U sub infinity ranging from a value of 30.9 m/s up to 73.4 m/s. Properties of the boundary layer for the airfoil and pressure fluctuations in the vicinity of the trailing-edge were examined. A scattered pressure field due to the presence of the trailing-edge was observed and is suggested as a possible sound producing mechanism for the trailing-edge noise

Effects of zinc on microalgal biofilms in intertidal and subtidal habitats

Microalgal biofilms are sensitive to environmental conditions. Impacts of contaminants on assemblages of marine biofilm are often investigated in laboratories or in mesocosms. Such experiments are rarely representative of the effects of contaminants on biofilms under natural conditions. Studies in field situations, with enough power to detect impacts, are necessary to develop a better understanding of the effects of contaminants on ecological processes. Metals are a common contaminant of marine systems and can cause disturbances to assemblages. Using a new technique to experimentally deliver contaminants to microalgal assemblages, hypotheses were tested regarding the effects of zinc on microalgal biofilms growing on settlement panels in subtidal and intertidal habitats. PAM fluorometry was used to assess the amount and physiological state of biofilms on panels. Control panels deployed for 1 month in each habitat had significantly greater amounts of biofilm than those exposed to zinc. After deployment for 3 months, the results varied with location. The observed effects on the biofilm did not, however, cause significant changes in the macro-invertebrate assemblages that developed on the panels

Towards developing an industry led educational framework using LEAN approach

The poor performance and inefficient manner in which the construction industry operates has been recognised through a variety of combined government and industry initiatives over the years. A major challenge towards improvement is recognised as lying with education and industry stakeholders actively creating closer and more effective relationships to facilitate a greater mutual understanding. The application of Information Technology (IT) systems can well enhance ‘Lean’ initiatives through improving process flow, reduction of the non-added value activities, better meet customers’ requirements and adding value which will increase the performance of the industry. This paper presents a project that is focused on developing an industry led framework for educational training programmes. The outcomes of two workshops organised with the industry that have resulted in a Continued Professional Development (CPD) training framework comprising of three distinct levels in terms of strategic, operational and technology aspects of that particular key area are discussed. The essence of this work is based on adopting the ‘Lean’ approach and adding value by identifying the IT skills gaps recognised ‘by the industry’ ‘for the industry’ and addressing them in developing training programmes

Identification of Specific Learning Disabilities: Georgia School Psychologists\u27 Perceptions

An on-line survey was conducted to investigate the assessment practices and perceptions of 366 practicing school psychologist in the state of Georgia concerning various operational components, and the use of RTI when determining SLD eligibility. Results were analyzed using ordinal logistic regression to determine if psychologists’ perceptions could be predicted based on various explanatory variables. Results revealed that a little over half of the respondents preferred assessment of cognitive processing deficits evidenced through patterns of strengths and weaknesses for establishing SLD classification; while well over two-thirds continue to also value analysis of cognitive ability (IQ) scores. Psychologists’ assessment practices were consistently predicted based on professional membership affiliation. Perceptions of the use of RTI in the operationalization of SLD, as well as, psychologists’ desire and ability to fulfill various leadership roles and responsibilities within RTI programs, were significantly impacted by the quality of the RTI program in the schools that respondents worked. This research begins to answer many questions concerning the perceptions and assessment practices of school psychologists across Georgia. Findings from this study provide important insight into school psychologists’ professional practices which is the first step to improving the accuracy, fidelity, and consistency of SLD identification methods

Damage Detection Analysis Using Lamb Waves in Restricted Geometry for Aerospace Applications

Today many USAF aircraft are approaching the end of their projected service life. However, those aircraft, such as the F-15 Eagle, are still being operated to accomplish the mission of the USAF. As the F-15 ages the required maintenance increases, as does the risk of structural failure. A goal of structural health monitoring (SHM) programs is to increase aircraft safety by monitoring areas known to have structural failures. Currently, time intensive manual inspections are used to monitor failure “hotspots” decreasing the readiness of the F-15 fleet. The lead ziconate titanate (PZT) is a commonly used piezoelectric transducer that has shown the potential to detect damage in aircraft structures without time consuming manual inspections. However, many locations where damage has occurred that have been identified by the USAF for SHM systems have restricted geometries consisting of thickness changes and boundary surfaces located near the damage. The restricted geometry presents challenges when using PZT sensors because of the interference of reflected waves coming off of boundary surfaces, and the behavior of the signals going through thickness changes. For this research, a location has failed on multiple F-15 aircraft and has been selected as a basis to evaluate some of the challenges of using PZT sensors for SHM. The goal of this research is to detect fatigue cracks in plates that represent the restricted geometry of the aircraft bulkhead so as to determine if a real damage detection system could be built for F-15 bulkheads. This research shows that detecting closed fatigue cracks can be more challenging than detecting cracks opened by a static load, but applying static loads present new challenges