Analysis of nonequilibrium air streams in the Ames 1-foot shock tunnel

Aerodynamic and thermodynamic calibration of nonequilibrium air flow in Ames 1-foot shock tunne

Performance of a Combustion Driven Shock Tunnel with Application to the Tailored- Interface Operating Conditions

Performance characteristics of driven tube portion of combustion driven wind tunnel designed for quasi-steady reservoir condition

Academic freedom in Europe: time for a Magna Charta?

This paper is a preliminary attempt to establish a working definition of academic freedom for the European Union states. The paper details why such a definition is required for the European Union and then examines some of the difficulties of defining academic freedom. By drawing upon experience of the legal difficulties beset by the concept in the USA and building on previous analyses of constitutional and legislative protection for academic freedom, and of legal regulations concerning institutional governance and academic tenure, a working definition of academic freedom is then derived. The resultant definition which, it is suggested, could form the basis for a European Magna Charta Libertatis Academicae, goes beyond traditional discussions of academic freedom by specifying not only the rights inherent in the concept but also its accompanying duties, necessary limitations and safeguards. The paper concludes with proposals for how the definition might be tested and carried forward

Integrating plant physiology into simulation of fire behavior and effects

Wildfires are a global crisis, but current fire models fail to capture vegetation response to changing climate. With drought and elevated temperature increasing the importance of vegetation dynamics to fire behavior, and the advent of next generation models capable of capturing increasingly complex physical processes, we provide a renewed focus on representation of woody vegetation in fire models. Currently, the most advanced representations of fire behavior and biophysical fire effects are found in distinct classes of fine-scale models and do not capture variation in live fuel (i.e. living plant) properties. We demonstrate that plant water and carbon dynamics, which influence combustion and heat transfer into the plant and often dictate plant survival, provide the mechanistic linkage between fire behavior and effects. Our conceptual framework linking remotely sensed estimates of plant water and carbon to fine-scale models of fire behavior and effects could be a critical first step toward improving the fidelity of the coarse scale models that are now relied upon for global fire forecasting. This process-based approach will be essential to capturing the influence of physiological responses to drought and warming on live fuel conditions, strengthening the science needed to guide fire managers in an uncertain future

Experimental Verification of the Aerodynamics of Stream Thrust Probes

Determining the local stream thrust (a vector quantity) from a measured pitot pressure (a scalar quantity) requires either knowledge of the flow direction or a probe shape that compensates for flow direction. This compensation ideally would make the measured pressure directly proportional to the component of momentum along the probe axis. The flow angle sensitivity required to resolve this component of momentum was previously determined theoretically. A proposed probe nose shape was analyzed using computational fluid dynamics (CFD) and was found to produce a flow angle sensitivity close to the required sensitivity. In the current work, the proposed nose shape was tested in a wind tunnel at Mach numbers 1.67, 2.45, and 3.48 at angles of attack from 0 to 15 deg. The test results indicate that the flow angle sensitivity of the proposed nose shape agrees with the required sensitivity to within 1 percent up to a flow angle of 15 deg

Diurnal Pine Bark Structure Dynamics Affect Properties Relevant to Firebrand Generation

Firebrands are an important agent of wildfire spread and structure fire ignitions at the wildland urban interface. Bark flake morphology has been highlighted as an important yet poorly characterized factor in firebrand generation, transport, deposition, and ignition of unburned material. Using pine species where bark flakes are the documented source of embers, we conducted experiments to investigate how bark structure changes in response to diurnal drying. Over a three-day period in a longleaf pine (Pinus palustris Mill.) stand in Florida, we recorded changes in temperature, moisture content, and structure of bark across different facing aspects of mature pine trees to examine the effects of varying solar exposure on bark moisture. We further compared results to bark drying in a pitch pine (Pinus rigida Mill.) plantation in New Jersey. Under all conditions, bark peeled and lifted away from the tree trunk over the study periods. Tree bole aspect and the time of day interacted to significantly affect bark peeling. General temperature increases and moisture content decreases were significantly different between east and west aspects in pitch pine, and with time of day and aspect in longleaf pine. These results illustrate that bark moisture and flakiness is highly dynamic on short time scales, driven largely by solar exposure. These diurnal changes likely influence the probability of firebrand production during fire events via controls on moisture (ignition) and peeling (lofting)