Aerodynamic investigations of ventilated brake discs.

The heat dissipation and performance of a ventilated brake disc strongly depends on the aerodynamic characteristics of the flow through the rotor passages. The aim of this investigation was to provide an improved understanding of ventilated brake rotor flow phenomena, with a view to improving heat dissipation, as well as providing a measurement data set for validation of computational fluid dynamics methods. The flow fields at the exit of four different brake rotor geometries, rotated in free air, were measured using a five-hole pressure probe and a hot-wire anemometry system. The principal measurements were taken using two-component hot-wire techniques and were used to determine mean and unsteady flow characteristics at the exit of the brake rotors. Using phase-locked data processing, it was possible to reveal the spatial and temporal flow variation within individual rotor passages. The effects of disc geometry and rotational speed on the mean flow, passage turbulence intensity, and mass flow were determined. The rotor exit jet and wake flow were clearly observed as characterized by the passage geometry as well as definite regions of high and low turbulence. The aerodynamic flow characteristics were found to be reasonably independent of rotational speed but highly dependent upon rotor geometry

Numerical simulations of drainage flows on Mars

Data collected by Viking Landers have shown that the meteorology of the near surface Martian environment is analogous to desertlike terrestrial conditions. Geological evidence such as dunes and frost streaks indicate that the surface wind is a potentially important factor in scouring of the martian landscape. In particular, the north polar basin shows erosional features that suggest katabatic wind convergence into broad valleys near the margin of the polar cap. The pattern of katabatic wind drainage off the north polar cap is similar to that observed on Earth over Antarctica or Greenland. The sensitivity is explored of Martian drainage flows to variations in terrain slope and diurnal heating using a numerical modeling approach. The model used is a 2-D sigma coordinate primitive equation system that has been used for simulations of Antarctic drainage flows. Prognostic equations include the flux forms of the horizontal scalar momentum equations, temperature, and continuity. Parameterization of both longwave (terrestrial) and shortwave (solar) radiation is included. Turbulent transfer of heat and momentum in the Martian atmosphere remains uncertain since relevant measurements are essentially nonexistent

Depositional and deformational structures in three \u27esker-like\u27 ridges, southwestern Ontario

The Dundalk Till Plain in southwestern Ontario is crossed by five “esker-like” ridges, believed to have been formed simultaneously during the early stage of the mid-Port Burce Stadial. The three middle ridges are the focus of this research, with each ridge having a different topographic form, but the length of, and distance between, ridges are similar. Occurrences of differing depositional structures and the presence of deformational structures over short lateral and vertical distances reveal the complexity of processes involved. The dominant primary sedimentary structures are large-scale tabular cross-beds. Many individual cross-beds are composed of poorly sorted, matrix-supported gravels. High variability in the type and characteristics of depositional structures over a short lateral distance is common within sections. The majority of deformational structures consist of high angle reverse faults and normal faults, associated with ice-contact support. Other deformational structures include a lateral series of “V-shaped” wedges which are exposed in two of the “esker ridges”. Thin “till-like” units were observed in several sections as well as continuous units of the Tavistock Till and Elma Till, the latter being a new easternmost, known location of this till. Small-scale deformation is seen in sediments immediately above and below several of these tills and “till-like” units. From the location of the tills and the nature of the structures, revisions to the local stratigraphic record were suggested which place the formation of the eastern two eskers during the early phase of the mid-Port Bruce Stadial. The western ridge was formed later, by ice associated with the Tavistock Till. The summation of field observations of depositional and deformational structures, paleocurrents and laboratory results, indicate that the deposits are eskers and not interlobate moraine. The interpretation of these results and observations indicate that the western ridge was formed separately, the other two ridges having been created early by similar processes

Lesser Yellowlegs Tringa flavipes in Sumatra: new to S.E. Asia.

No abstract availabl

Physical measurement of a slow drag of a drag embedment anchor during sea trials

Anchor drag during operation of offshore structures could significantly alter the initial load design characteristics of a mooring system. Hence an estimation of anchor positions during operation is essential to identify whether slow or abrupt anchor motion occurs and might require the redeployment of an anchor. During storm conditions, monitoring of mooring tensions and structure motions at the South West Mooring Test Facility (SWMTF) revealed the slow drift motion of one anchor. This facility is a surface buoy with a three-legged, compliant mooring system designed to investigate mooring system behaviour for Marine Renewable Energy (MRE) devices. This paper presents i) some methods to identify the deployment anchor positions: numerical model, acoustics diver survey, and towed sonar ii) the analyses procedure, and estimations of slow drift anchor motion. The findings indicate that one drag embedment anchor moved slowly during a moderate but prolonged and isolated storm, before embedding again. The work demonstrates that anchor position can be accurately monitored and that anchor motion is not necessarily due to excessive peak loads

Use of an Internet-Based Hay Directory in Beef Cattle Extension Programming

Commodity directories are often considered services but can also be used to collect current information for use in Extension programming efforts. An Internet-based hay directory was established in response to beef cattle producer requests. Mississippi Hay Directory listing criteria and submission methods were chosen by Extension personnel to collect statewide hay production demographics and producer communication method use information. Analysis of directory listings over a 2-year period provided Extension personnel with valuable information for future producer education efforts. Directory evaluation results indicate that it was successful in achieving its objectives. Directory use by producers exceeded expectations and continues to expand

Carolina Rolling Stone

https://digitalcommons.library.umaine.edu/mmb-vp/2849/thumbnail.jp

A Data Fusion Technique to Detect Wireless Network Virtual Jamming Attacks

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Wireless communications are potentially exposed to jamming due to the openness of the medium and, in particular, to virtual jamming, which allows more energy-efficient attacks. In this paper we tackle the problem of virtual jamming attacks on IEEE 802.11 networks and present a data fusion solution for the detection of a type of virtual jamming attack (namely, NAV attacks), based on the real-time monitoring of a set of metrics. The detection performance is evaluated in a number of real scenarios

Sound propagation over uneven ground and irregular topography

The development of theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere is discussed. Irregular topography here is understood to imply a ground surface that (1) is not idealizable as being perfectly flat or (2) that is not idealizable as having a constant specific acoustic impedance. The study focuses on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence