1,722,384 research outputs found
Leading edge topography of blades - a critical review
No full textIn turbomachinery, their blade leading edges are critical to performance and therefore fuel efficiency, emission, noise, running and maintenance costs. Leading edge damage and therefore roughness is either caused by subtractive processes such as foreign object damage (bird strikes and debris ingestion) and erosion (hail, rain droplets, sand particles, dust, volcanic ash and cavitation) and additive processes such as filming (from dirt, icing, fouling, insect build-up). Therefore, this review focuses on the changes in topography induced by during service to blade leading edges and the effect of roughness and form on performance and efforts to predict and model these changes. The applications considered are focused on wind, gas and tidal turbines and turbofan engines. Repair and protection strategies for leading edges of blades are also reviewed. The review shows additive processes are typically worse than subtractive processes, as the roughness or even form change is significant with icing and biofouling. Antagonism is reported between additive and subtractive roughness processes. There are gaps in the current understanding of the additive and subtractive processes that influence roughness and their interaction. Recent work paves the way forward where modelling and machine learning is used to predict coated wind turbine blade leading edge delamination and the effects this has on aerodynamic performance and what changes in blade angle would best capture the available wind energy with such damaged blades. To do this generically there is a need for better understanding of the environment that the blades see and the variation along their length, the material or coated material response to additive and/or subtractive mechanisms and thus the roughness/form evolution over time. This is turn would allow better understanding of the effects these changes have on aerodynamic/ hydrodynamic efficiency and the population of stress raisers and distribution of residual stresses that result. These in turn influence fatigue strength and remaining useful life of the blade leading edge as well as inform maintenance/repair need
Tribological performance of surface texturing in mechanical applications - a review
No full textSurface textures have been of great interest within the tribology community with nearly 1500 paperspublished on this topic in the past two decades. With the pursuit of low emissions and environmentalsustainability, the application of surface texturing to mechanical systems to lower friction and controlwear is attracting increasing attention. There is no doubt that certain textured surfaces can have abeneficial effect on tribological performance but it is widely agreed that the optimization of texturesshould be carried out based on specific requirements of applications. The purpose of this review articleis to summarize the current state of the art in surface texturing applied to mechanical applications(cutting tools, piston-ring & cylinder liners, sealing and journal bearings)from the following aspects:application requirements, numerical/experimental testing and validation, and tribological perfor-mance of textured surfaces(wear and friction), as well as the limitations in texture designs whenapplied to certain applications. Patterns/grooves in the micron-scale are the most typical shapes beenstudied, and benefits of partial texturing are applicable for most of these mechanical applications.Friction reduction of up to 34.5% in cutting tools, 82% in piston-ring & cylinder-liners, 65% in sealsand 18% in journal bearings have been observed by experimental tests. Based on primary evidencefrom the literature, the last section provides general suggestions on current gaps in understanding andmodelling and suggestions for future research directions
A new species of the genus Mawsonascaris Sprent, 1990 (Nematoda: Ascaridida) from Glaucostegus granulatus (Cuvier) (Rajiformes: Rhinobatidae) in the Taiwan Strait, with remarks on the systematic status of Raphidascaroides myliobatum Yin & Zhang, 1983
No full textLi, Liang, Xu, Zhen, Zhang, Lu-Ping (2012): A new species of the genus Mawsonascaris Sprent, 1990 (Nematoda: Ascaridida) from Glaucostegus granulatus (Cuvier) (Rajiformes: Rhinobatidae) in the Taiwan Strait, with remarks on the systematic status of Raphidascaroides myliobatum Yin & Zhang, 1983. Journal of Natural History 46 (21-22): 1307-1319, DOI: 10.1080/00222933.2012.655341, URL: http://dx.doi.org/10.1080/00222933.2012.65534
Figure 1 in A new species of the genus Mawsonascaris Sprent, 1990 (Nematoda: Ascaridida) from Glaucostegus granulatus (Cuvier) (Rajiformes: Rhinobatidae) in the Taiwan Strait, with remarks on the systematic status of Raphidascaroides myliobatum Yin & Zhang, 1983
No full textFigure 1. Mawsonascaris zhoui sp. nov. (A) Anterior part of female body, lateral view; (B) cephalic extremity of female, dorsal view; (C) cephalic extremity of female, lateral view; (D) cephalic extremity of female, ventral view; (E) caudal region of male, lateral view;Published as part of Li, Liang, Xu, Zhen & Zhang, Lu-Ping, 2012, A new species of the genus Mawsonascaris Sprent, 1990 (Nematoda: Ascaridida) from Glaucostegus granulatus (Cuvier) (Rajiformes: Rhinobatidae) in the Taiwan Strait, with remarks on the systematic status of Raphidascaroides myliobatum Yin & Zhang, 1983, pp. 1307-1319 in Journal of Natural History 46 (21-22) on page 1309, DOI: 10.1080/00222933.2012.655341, http://zenodo.org/record/520003
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Coatings and surface modification of alloys for tribo-corrosion applications
Full text linkThis review of the tribocorrosion of coatings and surface modifications covers nearly 195 papers and reviews that have been published in the past 15 years, as compared to only 37 works published up to 2007, which were the subject of a previous review published in 2007. It shows that the research into the subject area is vibrant and growing, to cover emerging deposition, surface modification and testing techniques as well as environmental influences and modelling developments. This growth reflects the need for machines to operate in harsh environments coupled with requirements for increased service life, lower running costs and improved safety factors. Research has also reacted to the need for multifunctional coating surfaces as well as functionally graded systems with regard to depth. The review covers a range of coating types designed for a wide range of potential applications. The emerging technologies are seen to be molten-, solution-, PVD- and PEO-based coatings, with CVD coatings being a less popular solution. There is a growing research interest in duplex surface engineering and coating systems. Surface performance shows a strong playoff between wear, friction and corrosion rates, often with antagonistic relationships and complicated interactions between multiple mechanisms at different scale lengths within tribocorrosion contacts. The tribologically induced stresses are seen to drive damage propagation and accelerate corrosion either within the coating or at the coating coating–substrate interface. This places a focus on coating defect density. The environment (such as pH, DO
2, CO
2, salinity and temperature) is also shown to have a strong influence on tribocorrosion performance. Coating and surface modification solutions being developed for tribocorrosion applications include a whole range of electrodeposited coatings, hard and tough coatings and high-impedance coatings such as doped diamond-like carbon. Hybrid and multilayered coatings are also being used to control damage penetration into the coating (to increase toughness) and to manage stresses. A particular focus involves the combination of various treatment techniques. The review also shows the importance of the microstructure, the active phases that are dissolved and the critical role of surface films and their composition (oxide or passive) in tribocorrosion performance which, although discovered for bulk materials, is equally applicable to coating performance. New techniques show methods for revealing the response of surfaces to tribocorrosion (i.e., scanning electrochemical microscopy). Modelling tribocorrosion has yet to embrace the full range of coatings and the fact that some coatings/environments result in reduced wear and thus are antagonistic rather than synergistic. The actual synergistic/antagonistic mechanisms are not well understood, making them difficult to model.</p
Assessment of Regional Shallow Landslide Stability Based on Airborne Laser Scanning Data in the Yingxiu Area of Sichuan Province (China)
Full text linkVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Isolation and Characterization of a Novel Proteinase Inhibitor from the Snake Serum of Taiwan Habu (Trimeresurus mucrosquamatus)
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