Experimental investigation of outdoor propagation of finite-amplitude noise

The outdoor propagation of finite amplitude acoustic waves was investigated using a conventional electroacoustic transmitter which was mounted on the ground and pointed upward in order to avoid ground reflection effects. The propagation path was parallel to a radio tower 85 m tall, whose elevator carried the receiving microphone. The observations and conclusions are as follows: (1) At the higher source levels nonlinear propagation distortion caused a strong generation of high frequency noise over the propagation path. For example, at 70 m for a frequency 2-3 octaves above the source noise band, the measured noise was up to 30 dB higher than the linear theory prediction. (2) The generation occurred in both the nearfield and the farfield of the transmitter. (3) At no measurement point was small-signal behavior established for the high requency noise. Calculations support the contention that the nonlinearity generated high frequency noise never becomes small-signal in its behavior, regardless of distance. (4) When measured spectra are scaled in frequency and level to make them comparable with spectra of actual jet noise, they are found to be well within the jet noise range. It is therefore entirely possible that nonlinear distortion affects jet noise

Sociology, Science and Sustainability: Developing Relationships in Scotland

This paper considers the application of the sociological imagination during the analysis of data collected during an ethnographic study of an environmental regulator, the Scottish Environment Protection Agency (SEPA). SEPA is tasked with implementing the European Water Framework Directive (WFD) in Scotland, which will radically alter the regulation of water use. Applying a sociological imagination allowed the researcher to advocate for a more interdisciplinary and equitable understanding of sustainable water use when feeding back initial research results at the end of the data collection period. The researchers introduced socialised definitions of the environment, which linked social justice and ecological concerns. These insights provided a challenge to the traditional bio-physical science focus of the organisational participants, for whom sustainability is a relatively new addition to their duties. The paper concludes by discussing the importance of developing these interdisciplinary relationships in the future.Sociological Imagination, Water Framework Directive, Sustainability Science, Consumer-Citizens

An Audible Demonstration Of The Speed Of Sound In Bubbly Liquids

The speed of sound in a bubbly liquid is strongly dependent upon the volume fraction of the gas phase, the bubble size distribution, and the frequency of the acoustic excitation. At sufficiently low frequencies, the speed of sound depends primarily on the gas volume fraction. This effect can be audibly demonstrated using a one-dimensional acoustic waveguide, in which the flow rate of air bubbles injected into a water-filled tube is varied by the user. The normal modes of the waveguide are excited by the sound of the bubbles being injected into the tube. As the flow rate is varied, the speed of sound varies as well, and hence, the resonance frequencies shift. This can be clearly heard through the use of an amplified hydrophone and the user can create aesthetically pleasing and even musical sounds. In addition, the apparatus can be used to verify a simple mathematical model known as Wood's equation that relates the speed of sound of a bubbly liquid to its void fraction. (c) 2008 American Association of Physics Teachers.Mechanical Engineerin

Some Simple Solutions to the Problem of Predicting Boundary-Layer Self-Induced Pressures

Simplified theoretical approaches are shown, based on hypersonic similarity boundary-layer theory, which allow reasonably accurate estimates to be made of the surface pressures on plates on which viscous effects are important. The consideration of viscous effects includes the cases where curved surfaces, stream pressure gradients, and leadingedge bluntness are important factors

Hypersonic performance, stability and control characteristics of a .0075 scale model Rockwell International 089B-139B orbiter configuration

An investigation was made in the Langley Continuous Flow Hypersonic Tunnel at a Mach number of 10.3 to study the hypersonic aerodynamic characteristics of a Rockwell International shuttle orbiter configuration. Tests were made at a Reynolds number of 790,000 x 106 based on body length with an angle-of-attack range of 10 to 35 deg and sideslip variations of +1 to -9 deg. The effects of elevon and body flap deflection were investigated

A molecular salt of tricyanomethanide anion and a N,N9- dianisylphenazinium dication: cooperative affects of methoxy…methoxy and CMN…N+ intermolecular contacts

A molecular salt of tricyanomethanide anion and a N,N9- dianisylphenazinium dication forms extended supramolecular assemblies that consist of unusual methoxy…methoxy and CMN…N+ intermolecular contacts

Mechanisms to improve integrative research at the science-policy interface for sustainable catchment management

Greater integration between researchers and policy makers is required to provide an evidence base that is transparent, integrated, and adaptive to support the complexities of sustainable catchment management. Opening-up and closing-down mechanisms are equally important in creating and establishing such an evidence base. We provide examples of both types based on our recent research and knowledge-transfer activities at the science-policy interface. Through our coordination role for the United Kingdom government we provide opening up physical and virtual forums for researchers and government science and policy staff to learn about and assess the gaps and uncertainties of the evidence base. Closing-down mechanisms are vital to policy cycles, in that they distil what is known and what is unknown. The Diffuse Pollution User Manual provides a valuable tool for policy and catchment management staff to assess the potential effectiveness of different combinations of remedial diffuse-pollution mitigation methods. It is vital that that opening-up and closing-down mechanisms are iteratively linked given the complexity and uncertainty of the science and policy cycles. Advances in integrative research at the science-policy interface are vital if there is to be a move to more deliberative policy making

The role of metrics in the governance of the water-energy-food nexus within the European Commission

Abstract Recent years have witnessed a growing interest in the water-energy-food (WEF) nexus in both academia and policy. This concept draws attention to the link between different environmental and societal domains, and potentially entails substantive shifts in governance processes. As a consequence, policy-makers and scientists have started to develop metrics to make these interactions and ‘trade-offs’ visible. However, it is unknown if current framings of the nexus and relevant quantified metrics either reinforce or challenge existing governance structures. This paper explores relationships between framings of the nexus, metrics and models of governance based on discussions with staff within the European Commission. Although narratives around the need for new metrics are situated in a conventional script about the use of evidence to change policy, our data indicate processes of co-production, by which the use (or non-use) of any new metrics is dependent on existing institutional practices; and will reflect dominant political orderings. In doing so we provide a critical analysis of the role of metrics in environmental governance, and direct attention to the discursive, institutional and political arrangements in which they are embedded and with which they are co-constitutive. Focusing on the cultural and institutional settings in which they are established and used, our study suggests that the question of metrics in the water-energy-food nexus needs to be explored as a problem of establishing a legitimate policy objective in the European Commission and EU policy-making more broadly.publishedVersio