End fixity to spiral strands undergoing cyclic bending

Based on a semi-empirical approach and guided by the previously reported experimental observations and theoretical work by the first author, it is suggested that for spiral strands with mean axial strains εc > 0.0025 and outside diameters d ≤ 40 mm, plane-section bending may reasonably be assumed in the course of theoretically determining the deflected shape, of the strands in the immediate vicinity of fixed end(s) with the proviso that, at the assumed ideal fixed end(s) to the spiral strands, p/d > 630, where p is the estimated minimum radius of curvature at the fixed end. It is also shown that, in practice, the effective fixed end to the spiral strands undergoing such cyclic bending is located not at the face of the zinc-socketed termination, but well within the socket itself; for an axially preloaded spiral strand of 39mm outside diameter, the effective point of end fixity is shown to be located inside the conical housing, about 60mm (or, say, 1.5 diameters) away from the face of the socket. The practical implications of the present findings as regards the traditional approach(es) for determining the minimum radii of curvature at the theoretically assumed (ideal) fixed end, the exact location of which in practice has invariably not (in the previous literature) been properly defined, are critically discussed with such estimated magnitudes of minimum radii of curvature often used as an input into various available models for design against spiral strand restrained bending fatigue. It is, perhaps, worth mentioning that, in the present terminology, the term 'spiral strand restrained bending fatigue' refers to those cases whereby strand fatigue failures near partially (or fully) restrained terminations of various types occur as a result of cyclic bending of the strand at the termination due to, for example, hydrodynamic or aerodynamic loading

Determination of the bending stiffness for a spiral strand

Owing to their peculiar construction, axially preloaded spiral strands undergo plane-section bending only for sufficiently small maximum lateral deflection/span ratios. Beyond a certain limit of this ratio, plane sections do not remain plane and, depending on the level of axial tension and imposed radius of curvature, interlayer slippage takes place, starting from the outer layer and spreading towards the centre of the strand. On the theoretical side, apart from one publication in the mid-1980s and some fairly recent publications by the first author and his associates, all other theoreticians have previously assumed either plane-section bending or, in many cases, have totally ignored the ever-present interwire friction, assuming that the individual helical wires act as simple helical springs. Previously reported experimental techniques, aimed at measuring the effective bending stiffness of helically wound cables, also largely suffer from major shortcomings. In the present paper, a novel experimental method is reported for obtaining reliable measurements of the effective bending stiffness of axially loaded spiral strands. It is very simple and relatively inexpensive to use in practice, for even very large (greater than, say, 100mm outside diameter) spiral strands. Effective bending stiffness measurements, based on this approach, are reported here for a 164mm outside diameter spiral strand (with axial loads of up to 3 MN), with these supported by a detailed theoretical analysis, which reinforces the generally sound nature of the proposed method

Simple determination of the axial stiffness for largediameter independent wire rope core or fibre core wire ropes

Raoof and Kraincanic recently developed two somewhat different theoretical models for analysing large-diameter wire ropes with either an independent wire rope core (IWRC) or a fibre core. Most importantly, unlike all of the previously available theories (with their often very lengthy mathematical formulations), very encouraging correlations have been found between Raoof and Kraincanic's theoretical predictions of wire rope axial stiffnesses and a fairly large body of experimental data from other sources, hence providing ample support for the reliability of both theoretical models. Raoof and Kraincanic's original models were, however, computer based and involved certain iterative procedures. This potential drawback for practical applications (in an area where, by tradition, the rule of thumb reigns supreme) is overcome in the present paper, which reports details of some simplified (but still accurate) procedures for predicting the no-slip and/or full-slip axial stiffnesses of wire ropes with either an independent wire rope core or a fibre core, with the proposed formulations being amenable to simple hand calculations using a pocket calculator, which is of value to busy practising engineers

Possible shortcomings of the calibration methods for certain non-destructive monitoring devices for helically wound steel cables

Coupled extensional–torsional behaviour of axially pre-loaded helically wound steel cables (wire ropes and/or spiral strands) under specific forms (i.e. unit-step, triangular, and half-sine) of impact loading are considered in some detail. The final closed-form formulations can handle both the no-slip and/or the traditionally used full-slip coupled extensional/torsional constitutive equations for helically wound cables, and describe the various characteristics of the resulting pairs of axial or torsional waves at any location along the cable with one end fixed against movement and the other end subjected to impact loading. By using extensive numerical results, which cover the full range of current manufacturing limits for the lay angle (with this being the sole controlling geometrical parameter as far as the axial/torsional stiffnesses are concerned), it is shown that significant differences exist between a number of axial/torsional wave characteristics, depending on whether the no-slip or the full-slip version of the constitutive relations is used in the analysis. It is demonstrated that modest increases in the magnitudes of the lay angles can lead to significant increases in the differences between the no-slip and the full-slip wave propagation characteristics. The present findings may have significant practical implications in relation to the currently adopted techniques used by industry for calibrating the electronic boxes, which are subsequently used as permanently installed devices, for the in situ detection of individual wire fractures under, say, fatigue loading associated with cable-supported structures

Major trauma from suspected child abuse: A profile of the patient pathway

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. Background Networked organised systems of care for patients with major trauma now exist in many countries, designed around the needs of the majority of patients (90% adults). Non-accidental injury is a significant cause of paediatric major trauma and has a different injury and age profile from accidental injury (AI). This paper compares the prehospital and inhospital phases of the patient pathway for children with suspected abuse, with those accidentally injured. Methods The paediatric database of the national trauma registry of England and Wales, Trauma Audit and Research Network, was interrogated from April 2012 (the launch of the major trauma networks) to June 2015, comparing the patient pathway for cases of suspected child abuse (SCA) with AI. Results In the study population of 7825 children, 7344 (94%) were classified as AI and 481 (6%) as SCA. SCA cases were younger (median 0.4 years vs 7 years for AI), had a higher Injury Severity Score (median 16vs9 for AI), and had nearly three times higher mortality (5.7%vs2.2% for AI). Other differences included presentation to hospital evenly throughout the day and year, arrival by non-ambulance means to hospital (74%) and delayed presentation to hospital from the time of injury (median 8 hours vs 1.8 hours for AI). Despite more severe injuries, these infants were less likely to receive key interventions in a timely manner. Only 20% arrived to a designated paediatric-capable major trauma centre. Secondary transfer to specialist care, if needed, took a median of 21.6 hours from injury(vs 13.8 hours for AI). Conclusion These data show that children with major trauma that is inflicted rather than accidental follow a different pathway through the trauma system. The current model of major trauma care is not a good fit for the way in which child victims of suspected abuse present to healthcare. To achieve better care, awareness of this patient profile needs to increase, and trauma networks should adjust their conventional responses

Revisiting the 26.5°C Sea Surface Temperature Threshold for Tropical Cyclone Development

Abstract A high sea surface temperature is generally accepted to be one of the necessary ingredients for tropical cyclone development, indicative of the potential for surface heat and moisture fluxes capable of fueling a self-sustaining circulation. Although the minimum 26.5°C threshold for tropical cyclogenesis has become a mainstay in research and education, the fact that a nonnegligible fraction of storm formation events (about 5%) occur over cooler waters casts some doubt on the robustness of this estimate. Tropical cyclogenesis over subthreshold sea surface temperatures is associated with low tropopause heights, indicative of the presence of a cold trough aloft. To focus on this type of development environment, the applicability of the 26.5°C threshold is investigated for tropical transitions from baroclinic precursor disturbances in all basins between 1989 and 2013. Although the threshold performs well in the majority of cases without appreciable environmental baroclinicity, the potential for development is underestimated by up to 27% for systems undergoing tropical transition. An alternative criterion of a maximum 22.5°C difference between the tropopause-level and 850-hPa equivalent potential temperatures (defined as the coupling index) is proposed for this class of development. When combined with the standard 26.5°C sea surface temperature threshold for precursor-free environments, error rates are reduced to 3%–6% for all development types. The addition of this physically relevant representation of the deep-tropospheric state to the ingredients-based conceptual model for tropical cyclogenesis improves the representation of the important tropical transition-based subset of development events.</jats:p

Nitric oxide modulates expression of extracellular matrix genes linked to fibrosis in kidney mesangial cells

Mesangial cells are thought to be important mediators of glomerular inflammation and fibrosis. Studies have established a direct role for nitric oxide (NO) in the regulation of gene expression in mesangial cells. Representational difference analysis was used to investigate changes in gene expression elicited by the treatment of S-nitroso-L-glutathione in rat mesangial cells. Seven upregulated and 11 downregulated genes were identified. Four out of 11 downregulated genes (connective tissue growth factor, thrombospondin-1, collagen type I all and collagen type I alpha 2) are known to be linked to inflammation and fibrosis. Results were verified across species in mesangial cells treated with a series of NO donors using Northern blot analysis, quantitative real-time PCR and protein analysis methods. Induction of endogenous NO production by cytokine stimulation also triggered regulation of the genes. One example gene, connective tissue growth factor, was studied at the promoter level. Promoter-reporter gene studies in mesangial cells demonstrated that NO acts at the transcriptional level to suppress gene expression. Our results reveal a complex role of NO in regulating gene expression in mesangial cells and suggest an antifibrotic potential for NO

Understanding the relationship between ignition delay and burn duration in a constant volume vessel at diesel engine conditions

Experiments were performed in a constant volume vessel, with fuel sprays injected into the vessel at various different pressure and temperature conditions chosen to represent diesel engine operation at various loads. A range of diesel primary reference fuels (i.e. mixtures of cetane and heptamethylnonane) of varying cetane number (CN) were tested, and as expected lower CN fuels have longer ignition delays. Burn period was plotted against ignition delay and two distinct trends can be seen: “mainly diffusion” diesel combustion in which burn period decreases with ignition delay and “mainly pre-mixed” diesel combustion in which burn period increases with ignition delay. There is typically a minimum in plots of burn period versus ignition delay which represents the transition between the two types of combustion mode. Higher CN, higher engine load and higher boost pressure would seem to favour “mainly diffusion” combustion whilst lower CN, lower loads and non boosted conditions favour “mainly pre-mixed” combustion

Hereditary complement factor I deficiency

Summary We describe four cases (from three families) of hereditary factor I deficiency, bringing the total number of cases now reported to 23. In one family there are two affected siblings: one has suffered recurrent pyogenic infections; the other is asymptomatic. In the second family, the patient had recurrent pyogenic infections and a self-limiting vasculitic illness; in the third family, the patient suffered recurrent pyogenic and neisserial infections. All four patients had markedly reduced concentrations of C3 in the serum (family 1 propositus: 28%; family 1 asymptomatic sibling: 15%; family 2: 31%; and family 3: 31 % normal human serum) which was in the form of C3b. Low lgG2 levels may occur in primary C3 deficiency, and reduction in lgG2 concentration to 1.14 g/l (normal: 1.30-5.90 g/l) was found in the patient from family 2. Using radioligand binding assays, we demonstrated increased binding of C3b to erythrocytes in a patient with factor I deficiency. This C3b could not be cleaved by autologous serum but could be cleaved by normal serum or purified factor I. We review and compare the published cases of C3, factor H and factor I deficienc