Viscous and Aeroelastic Effects on Wind Turbine Blades. The VISCEL project. Part I: 3D Navier–Stokes Rotor simulations

Aerodynamic modelling of HAWT rotors by means of “engineering methods” has reached a saddle point, where no further development can be expected without a breakthrough in understanding the physics of unsteady, rotating three‐dimensional flows. However, such a breakthrough becomes ever more necessary, as the size of the wind turbines increases. With the experimental work in that direction being mostly limited to observing the phenomena and interpreting the associated mechanisms, and its increased cost, alternatives are being sought. The use of CFD techniques and state‐of‐the‐art Navier–Stokes solvers is considered a very serious contender, a belief shared by the members of the present consortium, which has worked on the VISCEL JOR3‐CT98‐0208 Joule III project. This project's goal was to determine the aerodynamic characteristics as well as the aeroelastic behaviour of wind turbine blades across their broad range of operational conditions, from attached to highly separated flow regimes. The work programme included specific tasks for the validation and assessment of existing 3D solvers, for the parametric study of 3D flow around realistic blades and for the investigation of aeroelastic stability, at the blade section level. Copyright © 2003 John Wiley & Sons, Ltd.     

A conserved sequence in tRNA and rRNA promoters of Lactococcus lactis

A tRNA operon (trnA) from Lactococcus lactis consisting of seven tRNA genes and a 5S rRNA gene was cloned and sequenced. Promoter-fusion of the trnA promoter to a promoter-less beta-galactosidase gene of Leuconostoc mesenteroides resulted in high levels of beta-galactosidase activity in L. lactis. Searching for sequences with similarity to the sequence of the promoter region revealed a consensus sequence of promoters preceeding rRNA operons and tRNA operons from Lactococcus species including a not previously described conserved sequence (AGTT).     

Esmolol potentiates reduction of minimum alveolar isoflurane concentration by alfentanil

The beta subunit of human chorionic gonadotropin is potentially encoded by six genes, which can be categorized into two types based on a sequence change at codon 117: GCC for the type I and GAC for the type II genes. We previously showed that, whereas type I genes were exclusively expressed in normal breast tissues, expression of type II genes was associated with malignant transformation (Bellet, D., et al. Cancer Res., 57: 516-523, 1997). We designed a simple and robust test (the CG117 assay) that measures the percentage of type II over both types of chorionic gonadotropin beta mRNAs. Normal breast tissues consistently had a negative CG117 index, whereas cancer breast tissues showed indexes ranging from 0 to 100%. The prognostic significance of the CG117 index was investigated in a series of 99 unilateral invasive primary breast cancer patients with known long-term outcome (median follow-up, 9 years). The CG117 index was positive in 48 (48.5%) of the 99 tumor mRNA samples. The index was not significantly associated with standard prognostic parameters, including clinical and macroscopic tumor size, histopathological grade, and lymph node status or steroid receptor status. Patients with a positive CG117 index in primary tumor mRNA had significantly shorter metastasis-free survival (P = 0.014) and overall survival (P = 0.038) after surgery, compared to patients with a negative index. The prognostic significance of the CG117 index persisted in Cox multivariate regression analysis, both for metastasis-free survival (P = 0.008) and overall survival (P = 0.016), together with lymph node status (P = 0.027 and P = 0.009, respectively). These findings indicate that the CG117 index may contribute to the identification of high-risk breast cancer patients.     

Arc fusion splices with improved strength (4.8 GPa) approaching thestrength of the fibre

For the first time it has been shown that a median splice strength (4.8 GPa) closely matching that of the fibre can be achieved using a commercial fusion splicer. This is achieved by carefully controlling the stripping process and the environmental conditions     

Neurohormonal activity in heart insufficiency

The maintenance of cardiac pumping ability in the presence of a primary disturbance of myocardial contractility and/or an excessive haemodynamic strain on the heart is dependent on several compensatory mechanisms. Particular attention has formerly been paid to the importance of the Frank-Starling mechanism and cardiac hypertrophy and dilatation in maintaining a blood supply sufficient to cover the metabolic needs of various tissues in heart failure. In recent years, however, it has been found that certain neurohormonal systems (the sympathetic nervous system, the renin-angiotensin-aldosterone system, atrial natriuretic peptide and several locally acting vaso-active substances) undergo considerable changes according to the degree of heart failure. These compensatory mechanisms support the circulation wholly or partially in acute heart failure, however sustained neurohormonal activation may be harmful in chronic heart failure, where several neurohormonal factors may be activated to ill-effect. The most significant neurohormonal systems and their importance in heart failure are reviewed on the basis of the available literature.     

Knowledge about asthma among Danish primary school teachers. Results of a questionnaire study

An anonymous questionnaire inquiry performed among 324 school teachers in the Randers area with the purpose of elucidating teachers' knowledge about asthma is presented. To a series of statements about asthma, the teachers should answer yes, no or don't know. A limited knowledge about asthma in children was found. The knowledge about medicamental treatment was particularly limited. Only 57 per cent knew that wheezing after physical exertion is a strong indicator of asthma. Only five per cent had received proper instruction. This latter group had a significantly better knowledge of medical treatment (p < 0.0001-0.05). It is recommended that instruction in children's diseases, especially asthma should be reintroduced in teachers' training colleges.     

Fat systems for bakery products

Fat systems for cake, Danish pastries and bread are described in terms of physical and chemical characteristics as well as performance. Results indicate that additives, such as surfactants and dough conditioners in well formulated fat systems, can increase tolerance, improve uniformity and extend storage life of baked products. The polar and nonpolar lipids naturally present in flour are shown to affect finished bread quality, with the polar lipids showing an improving effect. The apparently divergent trends in the development and use of specialized shortenings for specific baked products vs. the development and use of multipurpose bulk systems for a variety of baked products are reviewed. One of seven papers presented in the symposium “Fats and Oils in the Food Industry,” AOCS Meeting, Atlantic City, October 1971.     

What can possibly go wrong? Anticipatory work in space operations

This paper explores how different forms of anticipatory work contribute to reliability in high-risk space operations. It is based on ethnographic field work, participant observation and interviews supplemented with video recordings from a control room responsible for operating a microgravity greenhouse at the International Space Station (ISS). Drawing on examples from different stages of a biological experiment on the ISS, we demonstrate how engineers, researchers and technicians work to anticipate and proactively mitigate possible problems. Space research is expensive and risky. The experiments are planned over the course of many years by a globally distributed network of organizations. Owing to the inaccessibility of the ISS, every trivial detail that could possibly cause a problem is subject to scrutiny. We discuss what we label anticipatory work: practices constituted of an entanglement of cognitive, social and technical elements involved in anticipating and proactively mitigating everything that might go wrong. We show how the nature of anticipatory work changes between planning and the operational phases of an experiment. In the planning phase, operators inscribe their anticipation into technology and procedures. In the operational phase, we show how troubleshooting involves the ability to look ahead in the evolving temporal trajectory of the ISS operations and to juggle pre-planned fixes along these trajectories. A key objective of this paper is to illustrate how anticipation is shared between humans and different forms of technology. Moreover, it illustrates the importance of including considerations of temporality in safety and reliability research.     

Using hash tables to manage the time-storage complexity in a point location problem: Application to explicit model predictive control

The online computational burden of linear model predictive control (MPC) can be moved offline by using multi-parametric programming, so-called explicit MPC. The solution to the explicit MPC problem is a piecewise affine (PWA) state feedback function defined over a polyhedral subdivision of the set of feasible states. The online evaluation of such a control law needs to determine the polyhedral region in which the current state lies. This procedure is called point location; its computational complexity is challenging, and determines the minimum possible sampling time of the system. A new flexible algorithm is proposed which enables the designer to trade off between time and storage complexities. Utilizing the concept of hash tables and the associated hash functions, the proposed method solves an aggregated point location problem that overcomes prohibitive complexity growth with the number of polyhedral regions, while the storage–processing trade-off can be optimized via scaling parameters. The flexibility and power of this approach is supported by several numerical examples.