ADCP measurements from the ICESHELF 94 experiment

The ICESHELF 94 Experiment was conducted during April of 1994 from an ice camp in the Lincoln Sea at approximately 84 degrees N, 63 degrees W. An Acoustic Doppler Current Profiler (ADCP) was operated at the camp from 8 to 24 April. This report describes the ADCP configuration and presents the raw data recorded by the ADCP. Processing steps involved in computing horizontal velocities in geographic coordinates from the raw data are described, and time series and spectra of the resulting data are presented. Horizontal velocities with precision of about 1 cm/s were obtained between 27.7 m and 137.0 m depth with 7.8 m resolution. Data were obtained at five minute intervals, but averaged to 1 hr during processing to suppress instrument noise. Spectra show the velocity field to be dominated by variance at semi-siurnal frequency, with a maximum in energy between 50 and 110m depth. Maximum amplitudes of 8 to 10 cm/s were seen near 80 m depth. Velocities from an InterOcean S4 current meter deployed at the same site were compared to those from the ADCP. The largest differences were associated with peaks in the semi-diurnal oscilations, with the S4 underspeeding relative to the ADCP.Funding was provided by the Office of Naval Research through Contract No. N00014-90-J-1359

An Economic Study of the Effect of Android Platform Fragmentation on Security Updates

Vendors in the Android ecosystem typically customize their devices by modifying Android Open Source Project (AOSP) code, adding in-house developed proprietary software, and pre-installing third-party applications. However, research has documented how various security problems are associated with this customization process. We develop a model of the Android ecosystem utilizing the concepts of game theory and product differentiation to capture the competition involving two vendors customizing the AOSP platform. We show how the vendors are incentivized to differentiate their products from AOSP and from each other, and how prices are shaped through this differentiation process. We also consider two types of consumers: security-conscious consumers who understand and care about security, and na\"ive consumers who lack the ability to correctly evaluate security properties of vendor-supplied Android products or simply ignore security. It is evident that vendors shirk on security investments in the latter case. Regulators such as the U.S. Federal Trade Commission have sanctioned Android vendors for underinvestment in security, but the exact effects of these sanctions are difficult to disentangle with empirical data. Here, we model the impact of a regulator-imposed fine that incentivizes vendors to match a minimum security standard. Interestingly, we show how product prices will decrease for the same cost of customization in the presence of a fine, or a higher level of regulator-imposed minimum security.Comment: 22nd International Conference on Financial Cryptography and Data Security (FC 2018

The Horn, Polkemmet: Experimental Assessment of the Aerodynamic Response Characteristics. G.U. Aero Report 9609

A qualitative assessment of the aerodynamic response characteristics of the Horn, planned for Polkemmet Country Park, West Lothian, is presented. The assessment is based on scale model experiments conducted in the smoke flow visualisation wind tunnel in the Department of Aerospace Engineering, University of Glasgow for a range of flow conditions compatible with the expected wind environment. A number of adverse unsteady aerodynamic phenomena are identified which are highly dependent on wind direction. These include a dominant transient vortex system emanating from the mouth of the Horn, periodic vortex shedding from the neck and support mast, conical vortices generated on the Horn surface, and a general bluff body wake in the lee of the Horn. It is anticipated that the aerodynamic behaviour identified in the model tests persists, at least qualitatively, under full scale conditions. As a result, the potential exists for both aerodynamically induced transient and periodic structural excitation of the Horn. Means of alleviating the adverse aerodynamic characteristics are available. However, any assessment of the effectiveness of such measures requires further experimental investigation

On the morphological deviation in additive manufacturing of porous Ti6Al4V scaffold: a design consideration

Additively manufactured Ti scaffolds have been used for bone replacement and orthopaedic applications. In these applications, both morphological and mechanical properties are important for their in vivo performance. Additively manufactured Ti6Al4V triply periodic minimal surface (TPMS) scaffolds with diamond and gyroid structures are known to have high stiffness and high osseointegration properties, respectively. However, morphological deviations between the as-designed and as-built types of these scaffolds have not been studied before. In this study, the morphological and mechanical properties of diamond and gyroid scaffolds at macro and microscales were examined. The results demonstrated that the mean printed strut thickness was greater than the designed target value. For diamond scaffolds, the deviation increased from 7.5 μm (2.5% excess) for vertical struts to 105.4 μm (35.1% excess) for horizontal struts. For the gyroid design, the corresponding deviations were larger, ranging from 12.6 μm (4.2% excess) to 198.6 μm (66.2% excess). The mean printed pore size was less than the designed target value. For diamonds, the deviation of the mean pore size from the designed value increased from 33.1 μm (-3.0% excess) for vertical struts to 92.8 μm (-8.4% excess) for horizontal struts. The corresponding deviation for gyroids was larger, ranging from 23.8 μm (-3.0% excess) to 168.7 μm (-21.1% excess). Compressive Young's modulus of the bulk sample, gyroid and diamond scaffolds was calculated to be 35.8 GPa, 6.81 GPa and 7.59 GPa, respectively, via the global compression method. The corresponding yield strength of the samples was measured to be 1012, 108 and 134 MPa. Average microhardness and Young's modulus from α and β phases of Ti6Al4V from scaffold struts were calculated to be 4.1 GPa and 131 GPa, respectively. The extracted morphology and mechanical properties in this study could help understand the deviation between the as-design and as-built matrices, which could help develop a design compensation strategy before the fabrication of the scaffolds

Pasture Land Management System Decision Support Software

Controlled or rotational grazing provides benefits to producers and society through profitable and sound management of grazing land and livestock. Pasture land management system (PLMS) is a decision support system developed to help university, government, and professionals provide technical pasture management assistance to beef and dairy producers. The PLMS focuses on the balance between seasonal forage supply and nutrient demand in a dairy or beef cattle operation. It allows users to explore and compare alternatives (dividing fields into multiple paddocks, changing stocking rates, and forage species) through a visual display and embedded simulation. Users enter a description of the farm by drawing a map. Maps can be drawn freehand, traced over a scanned image, or GIS data may be incorporated. Once map and field data are entered the grazing options are specified via input screens. Grazing systems can be easily compared without economic risk and with almost immediate feedback on how these alternative systems affect variables like milk production and pounds of beef sold. PLMS serves as both an educational tool and a strategic planning tool for evaluating alternative grazing operations and management related investments (website: http://clic.cses.vt.edu/PLMS/)

Analysis of model rotor blade pressures during parallel interaction with twin vortices

This paper presents and provides analysis of unsteady surface pressures measured on a model rotor blade as the blade experienced near parallel blade vortex interaction with a twin vortex system. To provide a basis for analysis, the vortex system was characterized by hot-wire measurements made in the interaction plane but in the absence of the rotor. The unsteady pressure response resulting from a single vortex interaction is then presented to provide a frame of reference for the twin vortex results. A series of twin vortex interaction cases are then presented and analyzed. It is shown that the unsteady blade pressures and forces are very sensitive to the inclination angle and separation distance of the vortex pair. When the vortex cores lie almost parallel to the blade chord, the interaction is characterized by a two-stage response associated with the sequential passage of the two cores. Conversely, when the cores lie on a plane that is almost perpendicular to the blade chord, the response is similar to that of a single vortex interaction. In all cases, the normal force response is consistent with the distribution of vertical velocity in the flow field of the vortex system. The pitching moment response, on the other hand, depends on the localized suction associated with the vortex cores as they traverse the blade chord

The Northwest Tropical Atlantic Station (NTAS) : NTAS-3 mooring turnaround cruise report

The Northwest Tropical Atlantic Station (NTAS) was established to address the need for accurate air-sea flux estimates and upper ocean measurements in a region with strong sea surface temperature anomalies and the likelihood of significant local air–sea interaction on interannual to decadal timescales. The approach is to maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 15°N, 51°W by successive mooring turnarounds. These observations will be used to investigate air–sea interaction processes related to climate variability. Deployment of the first (NTAS-1) and second (NTAS-2) moorings were documented in previous reports (Plueddemann et al., 2001, 2002). This report documents recovery of the NTAS-2 mooring and deployment of the NTAS-3 mooring at the same site. Both moorings used 3-meter discus buoys as the surface element. These buoys were outfitted with two Air–Sea Interaction Meteorology (ASIMET) systems. Each system measures, records, and transmits via Argos satellite the surface meteorological variables necessary to compute air–sea fluxes of heat, moisture and momentum. The upper 150 m of the mooring line were outfitted with oceanographic sensors for the measurement of temperature and velocity. The mooring turnaround was done on the WHOI R/V Oceanus, Cruise OC-385-5, by the Upper Ocean Processes Group of the Woods Hole Oceanographic Institution. The cruise took place between 12 and 23 February 2003. Deployment of the NTAS-3 mooring was on 15 February at approximately 14°49.5¢ N, 51°01.3¢ W in 4977 m of water. A 24- hour intercomparison period followed, after which the NTAS-2 mooring was recovered. This report describes these operations, as well as some of the pre-cruise buoy preparations.Funding was provided by the National Oceanic and Atmospheric Administration under Grant Number NA17RJ1223

Coastal mixing and optics experiment moored array data report

To investigate vertical mixing processes influencing the evolution of the stratification over continental shelves a moored array was deployed on the New England shelf from August 1996 to June 1997 as part of the Office of Naval Research's Coastal Mixing and Optics program. The array consisted of four mid-shelf sites instrumented to measure oceanic (currents, temperature, salinity, pressure, and surface gravity wave spectra) and meteorological (winds, surface heat flux, precipitation) variables. This report presents a description of the moored array, a summary of the data processing, and statistics and time-series plots summarizing the data. A report on the mooring recovery cruise and a summary of shipboard CTD surveys taken during the mooring deployment are also included.Funding was provided by the Office of Naval Research under Contract No. N00014-95-1-0339

The Northwest Tropical Atlantic Station (NTAS) : NTAS-4 mooring turnaround cruise report

The Northwest Tropical Atlantic Station (NTAS) was established to address the need for accurate air-sea flux estimates and upper ocean measurements in a region with strong sea surface temperature anomalies and the likelihood of significant local air–sea interaction on interannual to decadal timescales. The approach is to maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 15°N, 51°W by successive mooring turnarounds. These observations will be used to investigate air–sea interaction processes related to climate variability. Deployment of the first (NTAS-1), second (NTAS-2) and third (NTAS-3) moorings were documented in previous reports (Plueddemann et al., 2001; 2002; 2003). This report documents recovery of the NTAS-3 mooring and deployment of the NTAS-4 mooring at the same site. Both moorings used 3-meter discus buoys as the surface element. These buoys were outfitted with two Air–Sea Interaction Meteorology (ASIMET) systems. Each system measures, records, and transmits via Argos satellite the surface meteorological variables necessary to compute air–sea fluxes of heat, moisture and momentum. The upper 150 m of the mooring line were outfitted with oceanographic sensors for the measurement of temperature and velocity. The mooring turnaround was done on the NOAA ship Ronald H. Brown, Cruise RB-04-01, by the Upper Ocean Processes Group of the Woods Hole Oceanographic Institution. The cruise took place between 12 and 25 February 2004. The NTAS-3 buoy was found adrift and recovered on 19 February at 14°53.7’N, 51°22.8’W. Deployment of the NTAS-4 mooring was on 21 February at approximately 14°44.4’N, 50°56.0’W in 5038 m of water. A 30-hour intercomparison period followed, after which dragging operations to recover the lower portion of the NTAS-3 mooring commenced. This report describes these operations, as well as other work done on the cruise and some of the pre-cruise buoy preparations.Funding was provided by the National Oceanic and Atmospheric Administration under Grant No. NA17RJ1223 and the Cooperative Institute for Climate and Ocean Research (CICOR)