Computation of incompressible, three-dimensional turbulent boundary layers and comparison with experiment

Incompressible three dimensional, turbulent boundary layer (3DTBL) experiments were simulated numerically by integrating the boundary layer equations together with an algebraic eddy viscosity turbulence model. For the flow treated, the downstream portion, where the crossflow was large, was not predicted with the present computational method; the flow was significantly influenced by elliptic flow field effects. Departures from the boundary layer concept are indicated. Calculations agreed reasonably well with the mean flow development up to separation. In one experiment the normal pressure gradients were found to be neligible in regions with large skewing and allowed testing turbulence models using the boundary layer equations. The simulation of this flow compared favorably with the experimental data throughout the flow field and suggested the applicability of algebraic eddy viscosity models for 3DTBLs

Ecological and economic impacts of wildfires on an Appalachian oak forest in southern West Virginia

Oaks (Quercus spp.) are considered a fire adapted species and fire disturbances throughout the lifecycle have been proposed to be necessary for maintaining oak dominated stands. Wildfire has been blamed for significant losses in sawtimber volume. A total of 164 points were sampled in stands that had experienced between zero to six wildfires over 36 years in Cabwaylingo State Forest (CSF), West Virginia. The wildfires have affected different strata and species of forest vegetation in different ways. While total overstory density decreased from 242 to 38 TPA with increasing fire frequency, oak density was highest in areas of three fires. Although overall basal area decreased from 171 to 52 ft2/ac, oak basal area remained fairly constant at around 60 ft2/ac. Oaks in smaller (\u3c 8 inches) DBH classes were most abundant in areas of two to four wildfires. Total density of sapling sized stems increased with heightened fire occurrence. Oak saplings were significantly highest in density in areas of four fires. Neither oak nor non-oak seedling densities showed significantly differences by fire occurrences. Aggregate oak seedling height, however, was highest in areas that had burned four times. A regeneration assessment method by Steiner et al. (2008) revealed that expected oak stocking 30 years after complete harvest would be 73% in areas of three burns, decreasing with lower or higher fire occurrences. Our results indicate that oak advance reproduction is most competitive over non-oak species in those areas of CSF that have experienced two to four wildfires. Sawtimber volume loss due to cull increased from 181 to 752 Bdft/ac in areas experiencing from zero to six fire occurrences. Total net volume and net dollar value declined with increasing fire frequency ranging from 10,924 to 4,906 Bdft/ac and {dollar}1,208 to 589/ac, respectively; this is equal to a value decline of nearly 54%

Porównanie maksymalnego ciśnienia zamknięcia cewki moczowej mierzone cewnikiem typu mikrotip i cewnikiem wypełnionym powietrzem – badanie randomizowane

Background: Measurements of maximum urethral closure pressure (MUCP) are a part of urodynamic investigations preceding an incontinence surgery and a part of urethral function tests. Objectives: The aim of the study was to compare maximum urethral closure pressure determined by a microtip catheter with those measured by an air-charged catheter. Material and methods: A prospective randomized study in a tertiary referral centre. 122 female patients with urodynamic stress incontinence were randomly assigned to have their urethral pressure profi les measured at rest by both microtip and air-charged catheters. Intervention and Measurements: Each patient had three measurements taken by each catheter type. Means of the measurements were compared with regard to correlation and repeatability. For statistical analysis, an approach proposed by Bland-Altman was applied to assess the agreement between the two techniques. Results: Correlation coeffi cient between MUCP by the air-charged and the microtip catheter was r=0.8507(95% CI 0.7928 – 0.8934; pCel: Pomiar maksymalnego ciśnienia zamknięcia cewki moczowej (MUCP) jest częścią badania urodynamicznego poprzedzającego operacyjne leczenie nietrzymania moczu i częścią testow czynnościowych cewki moczowej. Celem pracy było porownanie maksymalnego ciśnienia zamknięcia cewki moczowej zmierzonego przy pomocy cewnika microtip i cewnika wypełnionego powietrzem. Materiał i metoda: Przeprowadzono prospektywne, randomizowane badanie w ośrodku trzeciego stopnia referencyjności. Do badania losowo włączono 122 kobiety z nietrzymaniem moczu, u których wykonywano profi l ciśnień w cewce moczowej w spoczynku przy pomocy zarówno cewnika microtip jak i cewnika wypełnionego powietrzem. Każda pacjentka miała wykonane trzy pomiary przy pomocy obu cewników. Średnie z pomiarów porównano w odniesieniu do korelacji i powtarzalności. Do celów statystycznych użyto metody Bland-Altmana oceniającej zgodność obu technik pomiarów. Wyniki: Współczynnik korelacji pomiędzy MUCP mierzonym cewnikiem powietrznym a cewnikiem microtip wynosił r=0,8507(95% CI 0,7928–0,8934;