Effect of cooling-hole geometry on aerodynamic performance of a film-cooled turbine vane tested with cold air in a two-dimensional cascade

The effect of the orientation and cooling-hole size on turbine-vane aerodynamic losses was evaluated. The contribution of individual vane regions to the overall effect was also investigated. Test configurations were based upon a representative configuration having 45 spanwise rows of holes spaced about the entire vane profile. Nominal hole diameters of 0.0254 and 0.0356 cm and nominal hole orientations of 35 deg, 45 deg, and 55 deg from the local vane surface and 0 deg, 45 deg, and 90 deg from the main-stream flow direction were investigated. Flow conditions and aerodynamic losses were determined by vane-exit surveys of total pressure, static pressure, and flow angle

Human Rights and Economic Democracy: Reinvigorating the Human Rights Movement

A 2018 report from the Intergovernmental Panel on Climate Change (IPCC) concluded that in order to avoid a seemingly inevitable ecological collapse that would bring intense suffering especially on the most marginalized and excluded sectors; the world needs to develop “rapid, far-reaching and unprecedented changes in all aspects of society”. There are many local experiences which demonstrate the possibilities of achieving these needed changes. There are a number of community organizations and associations, social movements, and municipal efforts, among others, with creative visions on this front. In Jackson, Mississippi, for example, Cooperation Jackson strives to be a means to help push for sustainable community development, economic democracy and community ownership. This is done through developing a network of cooperatives based on interconnected worker cooperatives, a cooperative training center, cooperative banks and more. Additionally, Cooperation Jackson is an active member organizing for Jackson Human Rights City, looking to further entrench into the city’s policies, practices and culture a resolution passed in 2014 which established a Human Rights Charter and a Human Rights Commission in the city of Jackson, Mississippi. The dire situation presented in the IPCC report alongside the inspiring local visions of movements for economic democracy, ecologically regenerative production, and community ownership over local resources, lead to a number of important questions. Can human rights catalyze the languages, practices and spaces needed for the excluded and marginalized to develop visions and mobilize examples of the “far-reaching” changes needed to avoid ecological collapse? How do human rights languages and practices enter into conversations over the democratic control over the means of production? How can these local experiences foment more conversations over economic and environmental democracy at the international level

Incidence loss for fan turbine rotor blade in two-dimensional cascade

The effect of incidence angle on the aerodynamic performance of a fan turbine rotor blade was investigated experimentally in a two dimensional cascade. The test covered a range of incidence angles from -15 deg to 10 deg and exit ideal critical velocity ratios from 0.75 to 0.95. The principal measurements were blade-surface static pressures and cross-channel survey of exit total pressure, static pressure, and flow angle. Flow adjacent to surfaces was examined using a visualization technique. The results of the investigation include blade-surface velocity distribution and overall kinetic energy loss coefficients for the incidence angles and exit velocity ratios tested. The measured losses are compared with those from a reference core turbine rotor blade and also with two common analytical methods of predicting incidence loss

Experiments in free shear flows: Status and needs for the future

Experiments in free turbulent flows are recommended with the primary concern placed on classical flows in order to augment understanding and for model building. Five classes of experiments dealing with classical free turbulent flows are outlined and proposed as being of particular significance for the near future. These classes include the following: (1) Experiments clarifying the effect of density variation owing to use of different gases, with and without the additional effect of density variation due to high Mach number or other effects; (2) experiments clarifying the role and importance of various parameters which determine the behavior of the near field as well as the condictions under which any of these parameters can be neglected; (3) experiments determining the cumulative effect of initial conditions in terms of distance to fully established flow; (4) experiments for cases where two layers of distinctly different initial turbulence structure flow side by side at the same mean speed; and (5) experiment using contemporary experimental techniques to study structure in free turbulent shear flows in order to compliment and support contemporary work on boundary layers

The geometry of manifolds and the perception of space

This essay discusses the development of key geometric ideas in the 19th century which led to the formulation of the concept of an abstract manifold (which was not necessarily tied to an ambient Euclidean space) by Hermann Weyl in 1913. This notion of manifold and the geometric ideas which could be formulated and utilized in such a setting (measuring a distance between points, curvature and other geometric concepts) was an essential ingredient in Einstein's gravitational theory of space-time from 1916 and has played important roles in numerous other theories of nature ever since.Comment: arXiv admin note: substantial text overlap with arXiv:1301.064

High Rate Of Right Ventricular Dysfunction After Negative Computed Tomographic Pulmonary Angiography

Background: Prior work found that 20% of patients with persistent dyspnea have right ventricular (RV) dysfunction. Many patients with suspected pulmonary embolism (PE) who have a negative CTPA have persistent yet unexplained dyspnea. We hypothesized that a substantial proportion of these patients have unrecognized RV dysfunction. We sought to estimate this proportion and develop criteria to predict RV dysfunction on echocardiography after CTPA negative for PE. Methods: This was a four-center, prospective study of patients with ≥one symptom or sign and ≥one risk factor for PE, and CTPA scan performed. To assess potential predictors of RV dysfunction, we recorded 82 clinical predictors in real time. These included clinical findings, 12-lead electrocardiography (ECG), exhaled volumetric CO2/O2, plasma D-dimer and fibrinogen measurements. Patients underwent echocardiography within one week. Isolated RV dysfunction was defined as normal LV function with either moderate-severe RV hypokinesis, or estimated RV systolic pressure >35 mmHg. To assess if RV dysfunction led to symptoms that prompted reevaluation, we compared the frequency of repeat CTPA within 90 days. CTPA scans were interpreted by two independent radiologists. Predictors of RV dysfunction were assessed using a univariate (P<0.1)-multivariate (P<0.05) statistical approach. Results: 647 patients were enrolled; 120 with CPTA positive for PE were excluded, and 97 were excluded because of lack of persistent dyspnea. Of the 430 remaining patients, 184 underwent echocardiography, which demonstrated isolated RV dysfunction in 34% (95% CI: 30-41%). 27% of patients with isolated RV dysfunction had repeat CTPA within 90 days, a significantly higher rate than in patients without echocardiography (4%, P=0.03, Chi Square) or a normal echocardiogram (5%, P=0.02). No repeat CTPA scan showed PE. Of 82 candidate predictors of examined, univariate analysis found only 6 significant: active malignancy, normal CTPA, right bundle branch block on ECG, T-wave inversion in V1-V2 on ECG, history of COPD, and fibrinogen concentration. Of these six, multivariate logistic regression analysis found only normal CTPA as a significant predictor of isolated RV dysfunction. Conclusion: Patients with persistent dyspnea who have a normal CTPA performed for suspected PE have a high rate of unexplained isolated RV dysfunction on echocardiography. These patients are more likely to have persistent symptoms leading to unnecessary repeat CTPA in the short term. These findings form the starting point for a screening protocol to select patients with negative CTPA scanning for formal echocardiography and specialist referral to evaluate for pulmonary hypertension or other treatable causes of RV dysfunction

Estimating stand-level economic impacts of black bear damage to intensively managed forests

Black bears (Ursus americanus Pallas, 1780) peel conifers in early spring to forage on energy-rich vascular tissues, resulting in damage to timber stands. The objective of our study was to develop and demonstrate a conceptual framework and methods for estimating stand-level volume and economic losses from black bear damage. We created tree lists from surveys of healthy and bear-damaged trees in timber stands of western Washington and Oregon. The forest growth model Forest Vegetation Simulator (FVS) was used to project stand volume under two damage scenarios and an undamaged scenario. One damage scenario (salvage) accounted for mortality and volume losses of fully and partially girdled trees; a second scenario (total loss) assumed complete loss of all trees peeled by black bears, regardless of peeling severity. The Fuel Reduction Cost Simulator (FRCS) was applied to estimate the value of logs delivered to the mill after accounting for logging and hauling costs associated with harvest. Present value of stands was calculated to translate volume losses into economic losses associated with bear damage. Economic losses ranged from 4% to 16% (salvage) and from 17% to 46% (total loss) of net present value. Our approach can be adapted for other forest settings and for forest management plans that assess wildlife damage. L’ours noir (Ursus americanus Pallas, 1780) arrache l’écorce des conifères tôt au printemps pour se nourrir des tissus vasculaires riches en énergie et cause des dommages aux peuplements forestiers. L’objectif de notre étude consistait à élaborer et présenter un cadre conceptuel et des méthodes pour estimer à l’échelle du peuplement les pertes de volume ainsi que financières dues aux dommages causés par l’ours noir. Nous avons créé des listes d’arbres sains et d’arbres endommagés par les ours à partir des inventaires de peuplements forestiers de l’ouest des États de Washington et de l’Oregon. Un modèle de croissance de la forêt, le simulateur de végétation forestière, a été utilisé pour prévoir le volume d’un peuplement selon deux scénarios comportant des dommages et un troisième qui n’en comporte pas. Un scénario comportant des dommages (récupération) tenait compte de la mortalité et des pertes de volume des arbres partiellement et complètement annelés; un second scénario (perte totale) assumait la perte complète de tous les arbres endommagés par les ours noirs, peu importe la sévérité des dommages. Le simulateur du coût de réduction des combustibles a été appliqué pour estimer la valeur des billes livrées à l’usine après avoir pris en compte les coûts de la coupe et du débardage associés à la récolte. La valeur actualisée des peuplements a été calculée pour traduire les pertes de volume en pertes financières associées aux dommages causés par les ours. Les pertes financières variaient de 4–16 % (récupération) et de 17–46 % (perte totale) de la valeur actualisée nette. Notre approche peut être adaptée à d’autres situations ainsi qu’aux plans d’aménagement forestier qui évaluent les dommages causés par la faune