2003 Estimated Machinery Costs for South Carolina Farms

Farm Management,

An Investigation in Implementing a C++ Voxel Game Engine with Destructible Terrain

In video games today, world geometry is often represented as a polygon mesh. While this representation is able to represent terrain, it must be done so using an elevation grid. For each X and Z location, an elevation grid stores the height of the terrain at that location. This has a major drawback: it is unable to allow terrain with overhangs and caves, and is unable to allow for destructible terrain. In this project, an alternative technique using voxels is explored to overcome these limitations for a game engine. A voxel is the 3D equivalent of a pixel and allows for 3D model manipulation by adding and removing discrete units. Because voxel objects require O(n^3) memory to represent, a number of challenges must be overcome to allow efficient manipulation, including effective use of cache memory, minimization of polygon count, efficient communication between the CPU and GPU, efficient collision detection when brute force methods require O(n^6) collision checks, and deletion of triangles from fixed-size Vertex Buffer Objects. The purpose of this project is to investigate and create solutions for these problems and successfully implement a simple game engine in C++ that allows for destructible terrain and terrain generation from mathematical formulas

2000 Estimated Machinery Costs for South Carolina Farms

Farm Management,

Convective Fingering of an Autocatalytic Reaction Front

We report experimental observations of the convection-driven fingering instability of an iodate-arsenous acid chemical reaction front. The front propagated upward in a vertical slab; the thickness of the slab was varied to control the degree of instability. We observed the onset and subsequent nonlinear evolution of the fingers, which were made visible by a {\it p}H indicator. We measured the spacing of the fingers during their initial stages and compared this to the wavelength of the fastest growing linear mode predicted by the stability analysis of Huang {\it et. al.} [{\it Phys. Rev. E}, {\bf 48}, 4378 (1993), and unpublished]. We find agreement with the thickness dependence predicted by the theory.Comment: 11 pages, RevTex with 3 eps figures. To be published in Phys Rev E, [email protected], [email protected], [email protected]

An Assessment of Disinfection-Related Water Chemistry at Public Pools and Spas in Louisville, Kentucky

The growth in the number of pools to more than 7.4 million in the U.S. has been accompanied by a rise in recreational water illnesses (RWIs). Effective pool management, though, can mitigate RWI risks. Inadequate management presumably occurs more frequently where training is less formalized and/or pool operation is a minor aspect of the job of the responsible pool manager(s). During summer 2018, weekly evaluations were performed at public venues in Louisville, Kentucky. Disinfectant levels and other items were monitored and compared with venue-specific (pool or spa) criteria. Among 1,312 venue surveys, 1,173 (89.4%) met criteria and 139 (10.6%) did not meet criteria. Overall, multivariable logistic regression showed a significant association between the likelihood of a venue meeting criteria and setting type. Specifically, hotels had 120% increased odds of not meeting criteria (adjusted odds ratio = 2.2; 95% confidence interval [1.3, 3.8]) compared with other settings. Despite spas having an 80% elevated odds of not meeting criteria compared with pools in a univariate analysis, upon adjusting for setting, spas were not associated with an increased risk of not meeting criteria. Research identifying reasons for these differences in meeting criteria between settings would be beneficial for informing public health interventions for aquatic environments

What is the appropriate diagnostic evaluation of fibroids?

Although transvaginal sonography (TVS) has inconsistent sensitivity (0.21-1.00) and specificity (0.53-1.00), its cost-efficiency and noninvasiveness make it the best initial test for ruling in fibroid disease (strength of recommendation [SOR]: B, based on expert opinion, a systematic review, and prospective studies). Sonohysterography (SHG) and hysteroscopy have superior sensitivity, specificity, and more discriminating positive and negative likelihood ratios for diagnosing fibroids than does TVS (SOR: B, systematic review). SHG is less painful, less invasive, and more cost-effective than hysteroscopy (SOR: B; single, prospective comparative study and cost comparison). Magnetic resonance imaging (MRI) had comparable precision to TVS in a single study, but it is too expensive to be a good initial test for fibroids (SOR: C, expert opinion and an uncontrolled prospective study). One study reported a strong correlation between ultrasound and bimanual examination (SOR: C, retrospective case review)

Afterbody Heat Flux Measurements in the NASA Ames HFFAF Ballistic Range

In order to measure afterbody heat fluxes over a model in the ballistic range, the required modifications to a proven technique for measuring forebody heat fluxes are described. This involves the use of an extended helium gas plume to remove the glowing wake and the use of special high conductivity, high temperature capable graphite-filled plastic for the afterbody. The models and test conditions are described. Data in the form of plots of the surface temperature of the models are presented. Finally, experimental and computational fluid dynamic (CFD) heat flux data for forebody and afterbody heat fluxes are presented and compared. Data are presented for a 45 degree sphere-cone (with a projecting rear stud) at 2.70 km/s and for a sphere at 4.76 km/s. Both models were launched into 76 Torr of CO2 gas. The experimental forebody heat fluxes were within 1.5% of the CFD values. The experimental afterbody heat fluxes were within 1% of the CFD values for the sphere, but only 51% of the CFD values for the sphere-cone

Techniques for Surface-Temperature Measurements and Transition Detection on Projectiles at Hypersonic Velocities--Status Report No. 2

The latest developments in a research effort to advance techniques for measuring surface temperatures and heat fluxes and determining transition locations on projectiles in hypersonic free flight in a ballistic range are described. Spherical and hemispherical titanium projectiles were launched at muzzle velocities of 4.6-5.8 km/sec into air and nitrogen at pressures of 95-380 Torr. Hemisphere models with diameters of 2.22 cm had maximum pitch and yaw angles of 5.5-8 degrees and 4.7-7 degrees, depending on whether they were launched using an evacuated launch tube or not. Hemisphere models with diameters of 2.86 cm had maximum pitch and yaw angles of 2.0-2.5 degrees. Three intensified-charge-coupled-device (ICCD) cameras with wavelength sensitivity ranges of 480-870 nm (as well as one infrared camera with a wavelength sensitivity range of 3 to 5 microns), were used to obtain images of the projectiles in flight. Helium plumes were used to remove the radiating gas cap around the projectiles at the locations where ICCD camera images were taken. ICCD and infrared (IR) camera images of titanium hemisphere projectiles at velocities of 4.0-4.4 km/sec are presented as well as preliminary temperature data for these projectiles. Comparisons were made of normalized temperature data for shots at approx.190 Torr in air and nitrogen and with and without the launch tube evacuated. Shots into nitrogen had temperatures ~6% lower than those into air. Evacuation of the launch tube was also found to lower the projectile temperatures by approx.6%