Leading-edge flow criticality as a governing factor in leading-edge-vortex initiation in unsteady airfoil flows

A leading-edge suction parameter (LESP) that is derived from potential flow theory as a measure of suction at the airfoil leading edge is used to study initiation of leading-edge vortex (LEV) formation in this article. The LESP hypothesis is presented, which states that LEV formation in unsteady flows for specified airfoil shape and Reynolds number occurs at a critical constant value of LESP, regardless of motion kinematics. This hypothesis is tested and validated against a large set of data from CFD and experimental studies of flows with LEV formation. The hypothesis is seen to hold except in cases with slow-rate kinematics which evince significant trailing-edge separation (which refers here to separation leading to reversed flow on the aft portion of the upper surface), thereby establishing the envelope of validity. The implication is that the critical LESP value for an airfoil–Reynolds number combination may be calibrated using CFD or experiment for just one motion and then employed to predict LEV initiation for any other (fast-rate) motion. It is also shown that the LESP concept may be used in an inverse mode to generate motion kinematics that would either prevent LEV formation or trigger the same as per aerodynamic requirements

Top, Bottom Quarks and Higgs Bosons

In this talk, I will discuss possible new physics effects that modify the interaction of Higgs boson(s) with top and bottom quarks, and discuss how to detect such effects in current and future high energy colliders.Comment: LaTeX, 16 pages including 5 figure

Effect of Pavement Texture on Traffic Noise

Noise from highway vehicles emanates primarily from engine exhausts, tire-pavement interaction) gears, and rattles. Studies have shown that at high speeds tires become the dominant generators of noise. Measurements on different road surfaces have produced different noise-versus-speed relationships (1). This led to the road surface adjustment used in the noise prediction procedure developed in NCHRP Report 117 (2). This adjustment called for a 5 dBA reduction for smooth surfaces (very smooth, seal-coated asphalt pavement) and a 5 dBA increase for rough surfaces (rough asphalt pavement with voids 1/2 inch (12 mm) or larger in diameter and grooved concrete). There was no adjustment for normal surfaces (moderately rough asphalt and concrete pavements). The surface descriptions are vague, and it is left to the discretion of the user to apply adjustments where applicable. Consideration was given initially in this report to \u27\u27rough surfaces, but the term was abandoned because it seemed vague and maybe misleading. Also, various degrees of roughness gave a wide range of noise levels. In fact, it appears that the terms smooth , normal , and rough address only that portion of tire noise generated by drumming or percussion of the tire against knobs in the pavement surface. Smooth does not distinguish smooth and dense from smooth and porous . It has been argued that the -5 dBA adjustment should not be used since some truck tires become excessively noisy on very smooth surfaces and inasmuch as such surfaces are presumed to be ready for renewal because of their inherent low friction characteristics (3). Minimum noise is believed to be associated with smoothness and an optimum porosity. In this report, surfaces are identified according to Kentucky specifications. Noise data were taken on all major types of surfaces presently used in Kentucky. A reference automobile was used to determine any difference in noise. Strip-chart records were made to evaluate the effect road surface type had on the noise of the entire traffic stream

Effect of Pavement Texture on Traffic Noise

Tire noise is one of the primary sources of highway noise, particularly at high speeds. Different types of road surfaces generate different noise levels. Noise data were collected on eight different surface types found in Kentucky. Noise measurements were made using a reference car, and noise recordings were obtained from the traffic stream. A reference truck was used for one test. It was found that portland cement concrete; Class I, Type A and A(Modified) bituminous concrete; chip seals; and open-graded, plant-mix seals were more or less normal surfaces in regard to generated noise. Sand-asphalt and Kentucky rock asphalt surfaces were about 3 dBA quieter (cars) than normal surfaces. Grooved portland cement concrete surfaces were approximately 4 dBA louder (cars) than normal surfaces. The surface type did not affect the noise emitted by trucks

Characteristics of Bicycle-Related, Motor Vehicle Accidents in Kentucky

The purpose of this study was to determine the characteristics associated with bicycle-related, motor vehicle accidents. Bicycle-related, motor vehicle accidents in Kentucky were analyzed. A sample of injury-producing bicycle accidents was also analyzed. It was found that cyclists 10 to 14 years of age were involved in the largest number of motor vehicle related accidents. Males were involved in four times as many accidents as females. Most accidents occurred in urban areas, mostly on residential streets. The majority of accidents resulted from errors by the cyclists. The most common type was the right-angle accident, but the leading types varied with cyclist\u27s age. Several factors were related to age and accident severity. The accidents were summarized by type and maneuver. The highest proportion was found between 3 and 7 p.m. Bicycle-related, motor vehicle accidents represented under 10 percent of all injury-producing bicycle accidents

Propagation of Traffic Noise

The effects of various traffic, ground cover, and geometric conditions on traffic noise propagation were evaluated in this study. There were two general methods of data collection. The first method consisted of using as many as four sound-level meters and graphic-level recorders to take simultaneous recordings of the traffic stream; the second method involved a constant noise source using a random noise generator. The L1.0 noise level reduction per doubling of distance was found to increase substantially when the traffic volume was less than 1,000 vehicles per hour. Wind speed and direction were found to have a large effect on noise propagation. Ground cover was also found to have a definite effect. Data were taken on short grass, tall weeds, tali grass, average grass, pavement, gravel, smooth dirt, snow, and plowed field. The drop-off per doubling of distance was found to decrease from about 4.5 dBA for receiver heights of 10 feet (3m) or below to 3.0 dBA for heights above 10 feet (3m). At heights above 10 feet (3 m), the type of ground cover did not have a significant influence on the propagation loss. Noise attenuation per doubling of distance remained constant back to about 400 feet (122m) where the drop-offs were influenced by the ambient noise level. Individual noise readings indicated that noise propagation was influenced by vehicle type and speed. Noise drop-off was larger for smaller percentage levels, but the differences decreased as volumes increased. Source height was also found to have an effect on noise propagation