Effect of ice floe on the strength, stability and fatigue of hybrid flexible risers in Artic sea. [Dataset]

The harsh and extreme conditions in the Arctic region pose new challenges for the technologies and standards established for traditional open water fields, as they may not be suitable for developments in ice-covered waters. Due to the unique challenges posed by the harsh and extreme environment of the Arctic regions, standardisation organisations such as ISO have developed guidelines for the design and construction of offshore structures in ice-covered waters. However, there are currently no specific guidelines for the design and construction of hybrid flexible riser systems containing a carbon fibre-reinforced polymer layer in ice-prone waters. This is considered a necessary development as more major operators are exploring deeper Arctic fields. In deep-water arctic seas, the use of a lightweight hybrid riser is important to alleviate the problem of high effective tension at the hang-off point. A flexible riser with a Carbon Fibre Reinforced Polymer (CFRP) pressure armour layer is designed to reduce the weight of the riser per metre of length. The materials and dimensions of each layer used in such a hybrid flexible riser have not been widely published due to the limited availability of operational data. The hybrid riser system, incorporating the CFRP composite layer serving as a pressure armour, is instrumental in the conveyance of fluids from the subsea manifold to the vessel located in a deep-water setup

Effect of chronic administration of Boerhaavia diffusa Linn. leaf extract on experimental diabetes in rats

Purpose: The root and aerial parts of Boerhaavia diffusa Linn. (Nyctaginaceae) were used in Ayurveda for the treatment of diabetes. The present study is aimed at evaluating the antidiabetic activity of chloroform extract of Boerhaavia diffusa leaves on chronic administration in streptozotocin-induced non-insulin-dependent diabetes mellitus (NIDDM) model diabetic rats. Methods: The blood glucose lowering activity of the leaf extract was studied in streptozotocin-induced (65 mg/kg, i.v.) NIDDM model diabetic rats after oral administration of the extract at daily doses of 50, 100 and 200 mg/kg body weight for four weeks and compared with glibenclamide. Blood samples were collected from the tail vein before and also at weekly intervals for four weeks from the first dose of drug administration and blood glucose was analyzed by glucose-oxidase method using a visible spectrophotometer. Results: The leaf extract of B. diffusa produced dose-dependent reduction in blood glucose in streptozotocin-induced NIDDM rats comparable to that of glibenclamide. The results indicate that the reduction in blood glucose produced by the extract is probably through rejuvenation of pancreatic b-cells or through extrapancreatic action. Conclusion: The chloroform extract of Boerhaavia diffusa has significant antidiabetic activity and this supports the traditional usage of the plant by Ayurvedic physicians for the control of diabetes. Keywords: Blood glucose, Boerhaavia diffusa, Diabetes mellitus Streptozotocin, Rats> Tropical Journal of Pharmaceutical Research Vol. 3 (1) 2004: pp. 305-30

The effect of ice floe on the strength, stability, and fatigue of hybrid flexible risers in the Arctic sea.

Flexible risers have proven to be a popular choice for deepwater exploration due to their ability to withstand functional and environmental stress while maintaining system integrity. In the challenging arctic conditions, lightweight hybrid composite flexible risers are likely to be employed to mitigate the increase in effective tension. This study investigates the strength and stability performance of production hybrid composite flexible risers with composite pressure armour in the harsh environmental conditions of the Arctic seas. At a water depth of 340 m, the flexible riser was analysed in various global configurations to evaluate the static, dynamic, and lamina-scale performance of its carbon fibre-reinforced thermoplastic polymer composite layer. The drifting ice in the region generated additional load on the riser system, and the effects of this ice on the riser design and its dynamic and lamina-level performances were also analysed. The results indicate that the current riser design incorporating the composite layer is insufficient to ensure system integrity without mitigating the effects of ice loading. The carbon fibre direction in each lamina must be optimised for excess axial stress emanating from the combined action of hoop, axial, and bending stresses. Finally, recommendations on how to improve the life of the lightweight hybrid composite riser in arctic conditions are provided

Effect of cell-size on the energy absorption features of closed-cell aluminium foams

The effect of cell-size on the compressive response and energy absorption features of closed-cell aluminium (Al) foam were investigated by finite element method. Micromechanical models were constructed with a repeating unit-cell (RUC) which was sectioned from tetrakaidecahedra structure. Using this RUC, three Al foam models with different cell-sizes (large, medium and small) and all of same density, were built. These three different cell-size pieces of foam occupy the same volume and their domains contained 8, 27 and 64 RUCs respectively. However, the smaller cell-size foam has larger surface area to volume ratio compared to other two. Mechanical behaviour was modelled under uniaxial loading. All three aggregates (3D arrays of RUCs) of different cell-sizes showed an elastic region at the initial stage, then followed by a plateau, and finally, a densification region. The smaller cell size foam exhibited a higher peak-stress and a greater densification strain comparing other two cell-sizes investigated. It was demonstrated that energy absorption capabilities of smaller cell-size foams was higher compared to the larger cell-sizes examined

Spreadsheet tools to estimate the thermal transmittance and thermal conductivities of gas spaces of an Insulated Glazing Unit

An Insulated Glazing unit (IGU) is constructed with two or more layers of glass panes sealed together by gas spaces in-between. IGUs are prevalent in windows, doors and rooflights, primarily due to their improved thermal resistance. Today, most IGUs are either two or three layered. Adding further layers of glass improves thermal insulation but with the penalty of increased cost and weight. Low emissivity (Low-e) film coatings, when deposited on the glass panes, reduce long-wavelength radiative heat losses. Furthermore, filling the gas spaces with the inert gases (e.g. Argon, Krypton, Xenon and SF6), further reduce conduction and natural convection across the gap. In summary, higher thermal insulation performance of an IGU can be achieved with gas fillings and Low-e coatings on glass. This report discusses spreadsheets that have been developed, capable of estimating the thermal transmittance values of IGU, as per BS EN 673. The spreadsheet tools also have the ability to estimate the thermal conductivity of the gas spaces between the panes of IGU

Verification of calculation code THERM in accordance with BS EN ISO 10077-2

Calculation codes are useful in predicting the heat transfer features in the fenestration industry. THERM is a finite element analysis based code, which can be used to compute thermal transmittance of windows, doors and shutters. It is important to verify results of THERM as per BS EN ISO 10077-2 to meet the compliance requirements. In this report, two-dimensional thermal conductance parameters were computed. Three versions of THERM, 5.2, 6.3 and 7.1, were used at two successive finite element mesh densities to assess their comparability. The results were all compliant with the aforementioned British Standard

Curcumin Reduces Tumour Necrosis Factor-Enhanced Annexin V-Positive Microparticle Release in Human Vascular Endothelial Cells

PURPOSE: Circulating microparticles have been highlighted as biomarkers of cardiovascular disease state and progression. The aim of this study was to evaluate the effects of curcumin on microparticle release from endothelial cells undergoing TNF-induced cell activation and apoptosis. METHODS: This study evaluated the effects of curcumin on microparticle release, cytotoxicity, apoptosis, cell adhesion molecule expression and monocyte adhesion in EAhy926 human endothelial cells RESULTS: The results showed that the numbers of microparticles were increased by tumour necrosis factor (TNF) or the combination of TNF and cycloheximide (CHX). Curcumin attenuated microparticle release caused by TNF or TNF plus CHX treatments. The pretreatment by curcumin not only negated the accelerated cell death and apoptosis caused by TNF and CHX, but also diminished TNF-induced cell activation, as assessed by reduced surface expression of intercellular adhesion molecule 1, and adhesion of monocytes to endothelial monolayers CONCLUSION: Curcumin reduced microparticle release from endothelial cells undergoing cell activation and apoptosis, which supports its protective role in TNF-associated endothelial dysfunction, and highlights its potential use as a nutraceutical agent for vascular inflammatory diseases

Numerical analysis of thermal stresses around fasteners in composite metal foils

The process of composite metal foil manufacturing (CMFM) has reduced a number of limitations associated with commercial additive manufacturing (AM) methods. The existing metal AM machines are restricted by their build envelope and there is a growing market for the manufacture of large parts using AM. These parts are subsequently manufactured in fragments and are fastened together. This paper analyses the thermal stresses around cylindrical fasteners for three layered metal composite parts consisting of aluminium foil, brazing paste and copper foil layers. The investigation aims to examine the mechanical integrity of the metallurgically bonded aluminium/copper foils of 100 micron thickness manufactured in a disc shape. A cylindrical fastener set at an elevated temperature of 100 °C is fitted in the middle of the disc which results in a steady-state thermal distribution. Radial and shear stresses are computed using finite element method which shows that non-zero shear stresses developed by the copper layer inhibit the axial slippage of the fastener and thereby establishing the suitability of rivet joints for CMFM parts

Spreadsheet tools to estimate the thermal transmittance and thermal conductivities of gas spaces of an Insulated Glazing Unit

An Insulated Glazing unit (IGU) is constructed with two or more layers of glass panes sealed together by gas spaces in-between. IGUs are prevalent in windows, doors and rooflights, primarily due to their improved thermal resistance. Today, most IGUs are either two or three layered. Adding further layers of glass improves thermal insulation but with the penalty of increased cost and weight. Low emissivity (Low-e) film coatings, when deposited on the glass panes, reduce long-wavelength radiative heat losses. Furthermore, filling the gas spaces with the inert gases (e.g. Argon, Krypton, Xenon and SF6), further reduce conduction and natural convection across the gap. In summary, higher thermal insulation performance of an IGU can be achieved with gas fillings and Low-e coatings on glass. This report discusses spreadsheets that have been developed, capable of estimating the thermal transmittance values of IGU, as per BS EN 673. The spreadsheet tools also have the ability to estimate the thermal conductivity of the gas spaces between the panes of IGU

Verification of finite element analysis code CalculiX CrunchiX (ccx) in accordance with ISO 10211:2007

The design standard ISO 10211 provides four thermal problems; a square column, a composite structure, a multi-environment building envelope and an iron bar penetrating an insulation layer. Each test case is described in a standard summary, which includes benchmark target solutions. A numerical code is considered as compliant with the aforementioned standard, providing the solutions for the test cases are within the tolerances for set physical point temperatures and total heat flow. Analyses were conducted using CalculiX suite, an open source code that can build, solve and post-process finite element (FE) models. All FE models were discretized with both first and second order elements and their results compliant with the reference solutions