The effect of a particle travelling through a laminar boundary layer on transition

This study investigates how a particle travelling through an initially laminar boundary layer can lead to its breakdown to turbulence With increasing kerosene costs and an awareness of limited available oil reserves, laminar flow technologies are again being considered to realize the necessary efficiency increases of aircraft, and more detailed information on the operational issues is required. The adverse impact of flying through cirrus clouds has been simplified to the effect of a single particle on a laminar boundary layer over a zero-pressure gradient flat plate. First results indicate that the critical values could be substantially smaller than initially assumed

A new species of Dermopristis Kearn, Whittington & Evans-Gowing, 2010 (Monogenea: Microbothriidae), with observations on associations between the gut diverticula and reproductive system and on the presence of denticles in the nasal fossae of the host Glaucostegus typus (Bennett) (Elasmobranchii: Rhinobatidae)

Dermopristis cairae n. sp. (Microbothriidae) is described from the skin and possibly from the nasal fossae of the giant shovelnosed ray Glaucostegus typus (Bennett). The new species is distinguished from D. paradoxus Kearn, Whittington & Evans-Gowing, 2010 by its larger size, body shape, lack of transverse ridges on the ventral surface and absence of a seminal receptacle. Extensive short gut branches lie dorsal to the testes and adjacent to the coiled region of the vas deferens and the oo¨type, possibly reflecting high metabolic demand in these areas. Denticles are present in the lining of the nasal fossae of G. typus, providing a firm substrate for the cement-based attachment of a microbothriid. However, confirmation that D. cairae inhabits the nasal fossae of G. typus is required

ADAMTS proteinases: a multi-domain, multi-functional family with roles in extracellular matrix turnover and arthritis

Members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family are known to influence development, angiogenesis, coagulation and progression of arthritis. As proteinases their substrates include the von Willebrand factor precursor and extracellular matrix components such as procollagen, hyalectans (hyaluronan-binding proteoglycans including aggrecan), decorin, fibromodulin and cartilage oligomeric matrix protein. ADAMTS levels and activities are regulated at multiple levels through the control of gene expression, mRNA splicing, protein processing and inhibition by TIMP (tissue inhibitor of metalloproteinases). A recent screen of human cartilage has shown that multiple members of the ADAMTS family may be important in connective tissue homeostasis and pathology

The role of proteases in pathologies of the synovial joint

Synovial (diarthrodial) joints are employed within the body to provide skeletal mobility and have a characteristic structure adapted to provide a smooth almost frictionless surface for articulation. Pathologies of the synovial joint are an important cause of patient morbidity and can affect each of the constituent tissues. A common feature of these pathologies is degenerative changes in the structure of the tissue which is mediated, at least in part, by proteolytic activity. Most tissues of the synovial joint are composed primarily of extracellular matrix and key pathological roles in the degeneration of this matrix are performed by metalloproteinases such as matrix metallproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS). However, other proteases such as cathepsin K are likely to play an important role, especially in bone turnover. In addition to the cleavage of structural proteins, proteolytic activities are employed to regulate the activity of other proteases, growth factors, cytokines and other inflammatory mediators. Proteases combine to form complex regulatory networks, the correct functioning of which is required for tissue homeostasis and the imbalance of which may be a feature of pathology. A precise understanding of the proteases involved in these networks is required for a true understanding of the associated pathology

Enhancing the performance of Xanthan gum in water-based mud systems using an environmentally friendly biopolymer

Xanthan gum is commonly used in drilling fluids to provide viscosity, solid suspension, and fluid-loss control. However, it is sensitive to high temperatures and not tolerant of field contaminants. This paper presents an experimental study on the effects of an eco-friendly biopolymer (diutan gum) on xanthan gum (XC) in a water-based bentonite mud. Laboratory experiments were carried out for different compositions of the biopolymers in water-based bentonite muds formulated without salt and in water-based bentonite muds containing sodium chloride (NaCl). The rheological properties of the water-based bentonite muds formulated with XC (2 Ibm) and those of the water-based bentonite muds prepared using XC (1Ibm) and diutan gum (1Ibm) were measured using Model 1100 viscometer after aging at 25 °C, 100 °C, and 120 °C for 16 h. The API fluid loss and filter cake of the mud formulations were measured using HTHP filter press. The properties of the water-based bentonite muds containing only XC were compared with those of the water-based bentonite muds containing XC and diutan gum. Presented results show that combining diutan gum and xanthan gum in a ratio of 1:1 in a water-based bentonite mud enhances its performance with respect to fluid properties—apparent viscosity, gel strength, yield points, YP/PV ratio, LSRV, n, and K. The fluid formulations also showed favorable mud cake building characteristics. Experimental data also indicate a 16%, 19%, and 34% reduction in API fluid loss values for the water-based benitoite muds containing XC in the presence of diutan gum after aging at 25 °C, 100 °C, and 120 °C for 16 h, respectively. Experimental results also show that the water-based benitoite mud containing XC and diutan gum would cause less formation damage and was tolerant of contamination with a monovalent cation (Na+). The synergy of xanthan gum and diutan gum can, therefore, improve the performance of water-based drilling fluids

Maximum likelihood estimation of closed queueing network demands from queue length data

We propose maximum likelihood (ML) estimators for service demands in closed queueing networks with load-independent and load-dependent stations. Our ML estimators are expressed in implicit form and require only to compute mean queue lengths and marginal queue length probabilities from an empirical dataset. Further, in the load-independent case, we provide an explicit approximate formula for the ML estimator together with confidence intervals

Corrective receding horizon EV charge scheduling using short-term solar forecasting

Forecast errors can cause sub-optimal solutions in resource planning optimization, yet they are usually modeled simplistically by statistical models, causing unrealistic impacts on the optimal solutions. In this paper, realistic forecast errors are prescribed, and a corrective approach is proposed to mitigate the negative effects of day-ahead persistence forecast error by short-term forecasts from a state-of-the-art sky imager system. These forecasts preserve the spatiotemporal dependence structure of forecast errors avoiding statistical approximations. The performance of the proposed algorithm is tested on a receding horizon quadratic program developed for valley filling the midday net load depression through electric vehicle charging. Throughout one month of simulations the ability to flatten net load is assessed under practical forecast accuracy levels achievable from persistence, sky imager and perfect forecasts. Compared to using day-ahead persistence solar forecasts, the proposed corrective approach using sky imager forecasts delivers a 25% reduction in the standard deviation of the daily net load. It is demonstrated that correcting day-ahead forecasts in real time with more accurate short-term forecasts benefits the valley filling solution