A review of in-situ loading conditions for mathematical modelling of asymmetric wind turbine blades

This paper reviews generalized solutions to the classical beam moment equation for solving the deflexion and strain fields of composite wind turbine blades. A generalized moment functional is presented to effectively model the moment at any point on a blade/beam utilizing in-situ load cases. Models assume that the components are constructed from inplane quasi-isotropic composite materials of an overall elastic modulus of 42 GPa. Exact solutions for the displacement and strains for an adjusted aerofoil to that presented in the literature and compared with another defined by the Joukowski transform. Models without stiffening ribs resulted in deflexions of the blades which exceeded the generally acceptable design code criteria. Each of the models developed were rigorously validated via numerical (Runge-Kutta) solutions of an identical differential equation used to derive the analytical models presented. The results obtained from the robust design codes, written in the open source Computer Aided Software (CAS) Maxima, are shown to be congruent with simulations using the ANSYS commercial finite element (FE) codes as well as experimental data. One major implication of the theoretical treatment is that these solutions can now be used in design codes to maximize the strength of analogues components, used in aerospace and most notably renewable energy sectors, while significantly reducing their weight and hence cost. The most realistic in-situ loading conditions for a dynamic blade and stationary blade are presented which are shown to be unique to the blade optimal tip speed ratio, blade dimensions and wind speed

Computational modelling of structural integrity following mass loss in polymeric charred cellular solids

A novel computational technique is presented for embedding mass-loss due to burning into the ANSYS finite element modelling code. The approaches employ a range of computational modelling methods in order to provide more complete theoretical treatment of thermoelasticity absent from the literature for over six decades. Techniques are employed to evaluate structural integrity (namely, elastic moduli, Poisson’s ratios, and compressive brittle strength) of honeycomb systems known to approximate three-dimensional cellular chars. That is, reducing the mass of diagonal ribs and both diagonal-plus-vertical ribs simultaneously show rapid decreases in the structural integrity of both conventional and re-entrant (auxetic, i.e., possessing a negative Poisson’s ratio) honeycombs. On the other hand, reducing only the vertical ribs shows initially modest reductions in such properties, followed by catastrophic failure of the material system. Calculations of thermal stress distributions indicate that in all cases the total stress is reduced in re-entrant (auxetic) cellular solids. This indicates that conventional cellular solids are expected to fail before their auxetic counterparts. Furthermore, both analytical and FE modelling predictions of the brittle crush strength of both auxetic and conventional cellular solids show a relationship with structural stiffness

Computational actuator disc models for wind and tidal applications

This paper details a computational fluid dynamic (CFD) study of a constantly loaded actuator disc model featuring different boundary conditions; these boundary conditions were defined to represent a channel and a duct flow. The simulations were carried out using the commercially available CFD software ANSYS-CFX. The data produced were compared to the one-dimensional (1D) momentum equation as well as previous numerical and experimental studies featuring porous discs in a channel flow. The actuator disc was modelled as a momentum loss using a resistance coefficient related to the thrust coefficient

On the Deflexion of Anisotropic Structural Composite Aerodynamic Components

This paper presents closed form solutions to the classical beam elasticity differential equation in order to effectively model the displacement of standard aerodynamic geometries used throughout a number of industries. The models assume that the components are constructed from in-plane generally anisotropic (though shown to be quasi-isotropic) composite materials. Exact solutions for the displacement and strains for elliptical and FX66-S-196 and NACA 63-621 aerofoil approximations thin wall composite material shell structures, with and without a stiffening rib (shear-web), are presented for the first time. Each of the models developed is rigorously validated via numerical (Runge-Kutta) solutions of an identical differential equation used to derive the analytical models presented. The resulting calculated displacement and material strain fields are shown to be in excellent agreement with simulations using the ANSYS and CATIA commercial finite element (FE) codes as well as experimental data evident in the literature. One major implication of the theoretical treatment is that these solutions can now be used in design codes to limit the required displacement and strains in similar components used in the aerospace and most notably renewable energy sector

THE_PM_BOK_CODE

This paper puts forward the argument that PM is spreading because it is a well adapted collection of memes, and that the Project Management Institute (PMI®) Guide to the Project Management Body of Knowledge (PMBOK® Guide) version of project management (the PM_BOK Code) has more to do with the appearance of a capability for productivity than it does with actual productivity. It suggests that project management is evolving in a toxic manner, and that corporations will reap more benefit from it than people. The paper concludes with a call for a reformation of the PMBOK®

A randomised trial of an eight-week, once weekly primaquine regimen to prevent relapse of plasmodium vivax in Northwest Frontier Province, Pakistan.

BACKGROUND: Vivax malaria remains a major cause of morbidity in the subtropics. To undermine the stability of the disease, drugs are required that prevent relapse and provide reservoir reduction. A 14-day course of primaquine (PQ) is effective but cannot safely be used in routine practice because of its interaction with glucose-6-phosphate dehydrogenase (G6PD) deficiency for which testing is seldom available. Safe and effective use of PQ without the need for G6PD testing would be ideal. The efficacy and safety of an 8-week, once weekly PQ regimen was compared with current standard treatment (chloroquine alone) and a 14-day PQ regimen. METHODS AND PRINCIPAL FINDINGS: 200 microscopically confirmed Plasmodium vivax patients were randomly assigned to either once weekly 8-week PQ (0.75 mg/kg/week), once weekly 8-week placebo, or 14-day PQ (0.5mg/kg/day) in North West Frontier Province, Pakistan. All patients were treated with a standard chloroquine dose and tested for G6PD deficiency. Deficient patients were assigned to the 8-week PQ group. Failure was defined as any subsequent episode of vivax malaria over 11 months of observation. There were 22/71 (31.0%) failures in the placebo group and 1/55 (1.8%) and 4/75 (5.1%) failures in the 14-day and 8-week PQ groups, respectively. Adjusted odds ratios were: for 8-week PQ vs. placebo-0.05 (95%CI: 0.01-0.2, p<0.001) and for 14-day PQ vs. placebo-0.01 (95%CI: 0.002-0.1, p<0.001). Restricted analysis allowing for a post-treatment prophylactic effect confirmed that the 8-week regimen was superior to current treatment. Only one G6PD deficient patient presented. There were no serious adverse events. CONCLUSIONS: A practical radical treatment for vivax malaria is essential for control and elimination of the disease. The 8-week PQ course is more effective at preventing relapse than current treatment with chloroquine alone. Widespread use of the 8-week regimen could make an important contribution to reservoir reduction or regional elimination where G6PD testing is not available. TRIAL REGISTRATION: ClinicalTrials.gov NCT00158587

Cost-effectiveness of malaria diagnosis using rapid diagnostic tests compared to microscopy or clinical symptoms alone in Afghanistan

Background Improving access to parasitological diagnosis of malaria is a central strategy for control and elimination of the disease. Malaria rapid diagnostic tests (RDTs) are relatively easy to perform and could be used in primary level clinics to increase coverage of diagnostics and improve treatment of malaria.&lt;p&gt;&lt;/p&gt; Methods A cost-effectiveness analysis was undertaken of RDT-based diagnosis in public health sector facilities in Afghanistan comparing the societal and health sector costs of RDTs versus microscopy and RDTs versus clinical diagnosis in low and moderate transmission areas. The effect measure was ‘appropriate treatment for malaria’ defined using a reference diagnosis. Effects were obtained from a recent trial of RDTs in 22 public health centres with cost data collected directly from health centres and from patients enrolled in the trial. Decision models were used to compare the cost of RDT diagnosis versus the current diagnostic method in use at the clinic per appropriately treated case (incremental cost-effectiveness ratio, ICER).&lt;p&gt;&lt;/p&gt; Results RDT diagnosis of Plasmodium vivax and Plasmodium falciparum malaria in patients with uncomplicated febrile illness had higher effectiveness and lower cost compared to microscopy and was cost-effective across the moderate and low transmission settings. RDTs remained cost-effective when microscopy was used for other clinical purposes. In the low transmission setting, RDTs were much more effective than clinical diagnosis (65.2% (212/325) vs 12.5% (40/321)) but at an additional cost (ICER) of US$4.5 per appropriately treated patient including a health sector cost (ICER) of US$2.5 and household cost of US$2.0. Sensitivity analysis, which varied drug costs, indicated that RDTs would remain cost-effective if artemisinin combination therapy was used for treating both P. vivax and P. falciparum. Cost-effectiveness of microscopy relative to RDT is further reduced if the former is used exclusively for malaria diagnosis. In the health service setting of Afghanistan, RDTs are a cost-effective intervention compared to microscopy.&lt;p&gt;&lt;/p&gt; Conclusions RDTs remain cost-effective across a range of drug costs and if microscopy is used for a range of diagnostic services. RDTs have significant advantages over clinical diagnosis with minor increases in the cost of service provision.&lt;p&gt;&lt;/p&gt

Cost-effectiveness of malaria diagnosis using rapid diagnostic tests compared to microscopy or clinical symptoms alone in Afghanistan.

BACKGROUND: Improving access to parasitological diagnosis of malaria is a central strategy for control and elimination of the disease. Malaria rapid diagnostic tests (RDTs) are relatively easy to perform and could be used in primary level clinics to increase coverage of diagnostics and improve treatment of malaria. METHODS: A cost-effectiveness analysis was undertaken of RDT-based diagnosis in public health sector facilities in Afghanistan comparing the societal and health sector costs of RDTs versus microscopy and RDTs versus clinical diagnosis in low and moderate transmission areas. The effect measure was 'appropriate treatment for malaria' defined using a reference diagnosis. Effects were obtained from a recent trial of RDTs in 22 public health centres with cost data collected directly from health centres and from patients enrolled in the trial. Decision models were used to compare the cost of RDT diagnosis versus the current diagnostic method in use at the clinic per appropriately treated case (incremental cost-effectiveness ratio, ICER). RESULTS: RDT diagnosis of Plasmodium vivax and Plasmodium falciparum malaria in patients with uncomplicated febrile illness had higher effectiveness and lower cost compared to microscopy and was cost-effective across the moderate and low transmission settings. RDTs remained cost-effective when microscopy was used for other clinical purposes. In the low transmission setting, RDTs were much more effective than clinical diagnosis (65.2% (212/325) vs 12.5% (40/321)) but at an additional cost (ICER) of US$4.5 per appropriately treated patient including a health sector cost (ICER) of US$2.5 and household cost of US$2.0. Sensitivity analysis, which varied drug costs, indicated that RDTs would remain cost-effective if artemisinin combination therapy was used for treating both P. vivax and P. falciparum. Cost-effectiveness of microscopy relative to RDT is further reduced if the former is used exclusively for malaria diagnosis. In the health service setting of Afghanistan, RDTs are a cost-effective intervention compared to microscopy. CONCLUSIONS: RDTs remain cost-effective across a range of drug costs and if microscopy is used for a range of diagnostic services. RDTs have significant advantages over clinical diagnosis with minor increases in the cost of service provision. TRIAL REGISTRATION: The trial was registered at ClinicalTrials.gov under identifier NCT00935688