Dynamic stall experiments on the NACA 0012 airfoil

The flow over a NACA 0012 airfoil undergoing large oscillations in pitch was experimentally studied at a Reynolds number of and over a range of frequencies and amplitudes. Hot-wire probes and surface-pressure transducers were used to clarify the role of the laminar separation bubble, to delineate the growth and shedding of the stall vortex, and to quantify the resultant aerodynamic loads. In addition to the pressure distributions and normal force and pitching moment data that have often been obtained in previous investigations, estimates of the unsteady drag force during dynamic stall have been derived from the surface pressure measurements. Special characteristics of the pressure response, which are symptomatic of the occurrence and relative severity of moment stall, have also been examined

Analysis of the development of dynamic stall based on oscillating airfoil experiments

The effects of dynamic stall on airfoils oscillating in pitch were investigated by experimentally determining the viscous and inviscid characteristics of the airflow on the NACA 0012 airfoil and on several leading-edge modifications. The test parameters included a wide range of frequencies, Reynolds numbers, and amplitudes-of-oscillation. Three distinct types of separation development were observed within the boundary layer, each leading to classical dynamic stall. The NACA 0012 airfoil is shown to stall by the mechanism of abrupt turbulent leading-edge separation. A detailed step-by-step analysis of the events leading to dynamic stall, and of the results of the stall process, is presented for each of these three types of stall. Techniques for flow analysis in the dynamic stall environment are discussed. A method is presented that reduces most of the oscillating airfoil normal force and pitching-moment data to a single curve, independent of frequency or Reynolds number

Fluorine gas as a cleaning agent for Apollo bulk-sample containers

A technique has been developed for cleaning Apollo bulk sample containers using fluorine gas as the cleaning agent

Prevalence, incidence, primary care burden and medical treatment of angina in Scotland: age, sex and socioeconomic disparities: a population-based study

Objective: To examine the epidemiology, primary care burden and treatment of angina in Scotland. Design: Cross-sectional data from primary care practices participating in the Scottish continuous morbidity recording scheme between 1 April 2001 and 31 March 2002. Setting: 55 primary care practices (362 155 patients). Participants: 9508 patients with angina. Results: The prevalence of angina in Scotland was 28/1000 in men and 25/1000 in women (p < 0.05) and increased with age. The prevalence of angina also increased with increasing socioeconomic deprivation from 18/1000 in the least deprived category to 31/1000 in the most deprived group (p < 0.001 for trend). The incidence of angina was higher in men (1.8/1000) than in women (1.4/1000) (p = 0.004) and increased with increasing age and socioeconomic deprivation. Socioeconomically deprived patients (0.48 contacts/patient among the most deprived) were less likely than affluent patients (0.58 contacts/patient among the least deprived) to see their general practitioner on an ongoing basis p = 0.006 for trend). Among men, 52% were prescribed ß blockers, 44% calcium channel blockers, 72% aspirin, 54% statins and 36% angiotensin converting enzyme inhibitors or angiotensin receptor blockers. The corresponding prescription rates for women were 46% (p < 0.001), 41% (p = 0.02), 69% (p < 0.001), 45% (p < 0.001) and 30% (p < 0.001). Among patients < 75 years old 52% were prescribed a β blocker and 58% a statin. The corresponding figures for patients ≥ 75 years were 42% (p < 0.001) and 31% (p < 0.001). Conclusions: Angina is a common condition, more so in men than in women. Socioeconomically deprived patients are more likely to have angina but are less likely to consult their general practitioner. Guideline-recommended treatments for angina are underused in women and older patients. These suboptimal practice patterns, which are worst in older women, are of particular concern, as in Scotland more women (and particularly older women) than men have angina

Study of the Epistle of Paul to the Romans 7:1-8:4 with special reference to the form, structure, and meaning of 7:7-25

Romans 7 is a famous orux interpretum. Its interpretation forms a Chapter of its own in the history of Pauline Studies. The purpose of this Thesis is to survey the field, identify the issues involved, indicate conclusions reached on these, and then suggest an approach to the problem which, we claim, meets many of the requirements of the case.Chapter 1 summarises the results of our investigations into the questions whioh belong to the sphere of "Introduction". We desoribe the Epistle as essentially a "creative synthesis". In assessing the Epistle a balance must be established between the background which is personal to Paul, the historical Church situation and the destination of the Letter. The purpose and structure of the Epistle are considered.Chapter 2 affirms the basic antithetical nature of Paul's thou$it and traces the development of the concept of law which belongs to this fundamental antithesis, until it becomes the major interest in Chapter 7.Chapter 3 explores the immediate context of the passage within which 7:7-25 is a digression.Chapter 4 extends the viewpoint to the Epistle a3 a whole. Our passage is related in particular to three other sections in the Epistle, namely, 1:18-3:20; 5:12-21; 9:1-11:36. The connecting link is the salvation history mode of thought.Chapter 5 oonoentrates attention on the understanding of the ??? in 7:7ff. A sketch is offered of the main interpretations which have been advanced, in order to give some appreciation of the history of the problem.Then note is taken of certain important attempts in recent times to clarify the problems in which positive contributions are made, in particular by ft.G. Kummel and R. Eultmana, An examination is made of other passages in Paul's writings from which light may be thrown on 7:7ff and the search for antecedents and parallels to the "I"-form is extended to the wider literary field. Attention is given to a possible relationship with Qumran. The conclusion is that the Old Testament and Judaism provide the relevant sources. Two major issues for the understanding of the are investigated - its relation to the Christian and then to Paul himself. A controlling esohatological tension is identified in each case, in the light of which negative answers are reached. Two lesser issues are dealt with - the primary theme of the passage is recognised as the function of the law in God's plan and the standpoint of the passage is defined as Christian.Chapter 6 proposes that 7:7-25 should be identified a3 an explicit dramatisation and arguments are advanced in support. The controverted issue of a Genesis allusion in vv7ff is dealt with exegetically with a positive conclusion. Factors in the preceding verses which predispose toward a dramatic portrayal are indicated. Hints are collected from the extensive literature and these supply tentative pointers in the direction w8 have travelled. Appeal is made to three essays of special interest, by P. Benoit, B. Ramm and H. Jonas. It is readily granted that a dramatic presentation is hardly what one would expect from the Hebrew background of Paul, but again predisposing factors can be adduced in Paul's frequent use of metaphor and apocalyptic imagery, in his use of the theological concept of "corporate personality", and in his personal adaptability. Arguments are led against too narrow an interpretation of ????? in the passage. A multiple use is in happy accord with our insistence on a dramatic portrayal.Chapter 7 seeks to analyse the passage in accordance with the view of its literary form which has been proposed. In this analysis exegesis is of first importanoe. Four scenes in the drama are identified, comprising vv7-11; 12-13; 14-24, 25a, to which there is appended a summarising conclusion or epilogue, v25b. The purpose of each scene and of the summarising conclusion is described and the content is dissected. In Scene 3, vv14-24, the proposal is made that a soliloquy is before us within the over-all dramatic portrayal. We claim that this insight helps to clarify some of the hitherto intractable problems. The essential continuity between vvl4ff and vv7ff is affirmed. The famous conflict or split is carefully analysed and is shown to consist of a conflict within a conflict, the one objective and the other subjective. Consideration is given to disputed issues - whether Paul is a systematic theologian, how his anthropological terms are to be understood, the extent to which he was influenced by Hebrew and by Greek culture.Chapter 8 presents the conclusions of our study. The search for a "key" to unlock all the problems is dismissed. The importance of an appreciation of the dramatic form and of attention to the eschatological factor is emphasised. The argument is summed up and five important questions are answered in the light of our investigation. The thesis ends with a summary of the main advantages resulting from the recognition of the dramatic form of 7:7-25

Non-noble catalysts and catalyst supports for phosphoric acid fuel cells

Tungsten carbide, which is known to be active for hydrogen oxidation and CO tolerant has a hexagonal structure. Titanium carbide is inactive and has a cubic structure. Four different samples of the cubic alloys Wx-1TixC were prepared and found to be active and CO tolerant. These alloys are of interest as possible phosphoric acid fuel cell catalysts. They also are of interest as opportunities to study the activity of W in a different crystalline environment and to correlate the activities of the surface sites with surface composition

Effect of artificially induced stress conditions on the growth of the medicinal plant Hypoxis hemerocallidea

H. hemerocallidea corms are a rich source of hypoxoside which is used medically. Certain aspects of cultivation of this plant have been investigated in this study. Herbicide treatments were undertaken as weeds pose a problem in cultivated lands, It was found that 2,4-D amine and glyphosate killed the H. hemerocallidea plants. Paraquat at low concentrations allowed good growth and yielded a good hypoxoside content. The control plants, however, grew the best and produced the most hypoxoside. H. hemerocallidea apparently prefers poor soils with little nutrients. High levels of nitrogen, phosphorus and potassium are needed initially to produce a good biomass. Once the plants have been established the fertilizer treatment can be discontinued. Best hypoxoside production was achieved when nitrogen levels were low. This finding is in line with the fact that these plants naturally grow well in poor soils. The plants survived and grew best in a clay/shale soil rather than on either a sandy or a grey prismic columnar soil. The hypoxoside content of plants grown on the clay/shale soil was the highest

An experimental study of dynamic stall on advanced airfoil section. Volume 2: Pressure and force data

Experimentally derived force and moment data are presented for eight airfoil sections that were tested at fixed and varying incidence in a subsonic two dimensional stream. Airfoil incidence was varied through sinusoidal oscillations in pitch over a wide range of amplitude and frequency. The surface pressure distribution, as well as the lift, drag, and pitching moment derived therefrom, are displayed in a uniform fashion to delineate the static and dynamic characteristics of each airfoil both in and out of stall