A Simplified Blade Model for Reliable Seismic Assessments of Wind Turbines

Wind turbines are dynamically complex structures. They entail slender towers, flexible foundations, and heavy rotor-nacelle-assembly (RNA). In the context of earthquake analysis, the RNA is often simplified as a rigid point mass which can suppress the modal contribution of blades from the global system dynamics and may further affect the reliability of seismic response of wind turbines. Other high-fidelity finite element (FE) blade models are difficult to implement due to the complex layup of composite materials and reduced computational efficiency. Thus, there is a need for an intermediate solution that allows the realistic and accurate consideration of blades in the seismic assessment of wind turbines. This study presents a meta-heuristic, problem-independent optimisation method, known as the genetic algorithm (GA), to identify simplified material and cross-sectional properties of a typical wind turbine blade. The properties are used to construct a simplified FE blade model that can be implemented in global wind turbine models. The optimised design solutions are examined with regards to the mechanical and dynamic response of a reference 5MW wind turbine having 61.5 m long blades. The accuracy of the modal behaviour validates the presented optimisation and simplified blade modelling approach and signifies the potential of its application in seismic assessments of wind turbines

Experimental Results of the Tribology of Aluminum in the Presence of Polytron Additive

Friction is an ever-present obstacle that causes energy loss in mechanical parts. To alleviate this nuisance, we carried out experimental studies on a brand new additive called Polytron to assess its role in the minimization of friction and wear. The wear, the volume wear rate, the wear coefficient, and the coefficient of friction of the aluminum surface were measured at room temperature with pin-on-disk tribometer without and with 10% Polytron in Helix oil. In the base oil Helix, their values were found to be 70 μm, 1.28×10−3mm3/min, 1.27×10−10m2/N, and 0.012, respectively, which with the incorporation of Polytron additive in the Helix oil correspondingly reduced to 20μm, 6.08×10−5mm3/min, 4.22×10−11m2N, and 0.004. The experimental verdict points to an ionic character of the additive in that it impregnates the crystal structure of the metal, thereby prompting a hard surface layer which subsequently curtails wear and friction

Unsteady Boundary-Layer Flow over Jerked Plate Moving in a Free Stream of Viscoelastic Fluid

This study aims to investigate the unsteady boundary-layer flow of a viscoelastic non-Newtonian fluid over a flat surface. The plate is suddenly jerked to move with uniform velocity in a uniform stream of non-Newtonian fluid. Purely analytic solution to governing nonlinear equation is obtained. The solution is highly accurate and valid for all values of the dimensionless time 0≤τ<∞. Flow properties of the viscoelastic fluid are discussed through graphs

Efficiency of Spectral Acceleration for Seismic Assessment of Offshore Wind Turbines

An efficient choice of intensity measure (IM) is vital for reliable estimation of structural performance. Offshore wind turbine (OWT) installations are continually planned and executed in active seismic regions, however, present understanding on their seismic vulnerability to various earthquake types and potentially suitable IMs to quantify the seismic response is yet incomprehensive. This study evaluates the efficiency of spectral acceleration Sa to describe seismic performance of OWTs for serviceability, ultimate and emergency shutdown conditions through a probabilistic regression model. In addition, sensitivity of structural reliability to pulse and non-pulse records is examined. Results emphasize the efficiency of Sa(T1) and AvgSa at serviceability, ultimate limit state and emergency shutdown, respectively, with reasonable dispersion. Regardless of pulse and non-pulse classification, 5MW is found vulnerable to crustal records with strong vertical acceleration and PGV content

Curcumin has Curative Effect on Isoniazid-Rifampicin Induced Hepatotoxicity

Background: Anti-tuberculosis drugs-induced hepatotoxicity is associated with oxidative stress. Curcumin is a powerful antioxidant and has been found to protect the liver from the damaging effects of oxidative stress. The study aimed to assess the curative and protective effects of Curcumin against hepatotoxicity induced by anti TB- drugs (Isoniazid-Rifampicin) by using an experimental model of Albino rabbits. Methods: Albino rabbits(n=24) were divided into four groups. Group A was the control group, Group B administered Isoniazid (INH) (50 mg/kg/d) and Rifampicin (RMP) (100 mg/kg) alone, Group C received both INH+RMP and Curcumin (60 mg/kg) before and during induction. Group D received INH (50 mg/kg/d) and RMP (100 mg/kg/d) for 7 days, followed by 7 days of Curcumin (60 mg/kg/d). Biochemical testing and liver morphological histopathology was done for all groups. All values were recorded in mean ± standard deviation. Results: Anti-Tuberculosis drugs increased Alanine Transaminase (ALT), Aspartate Transaminase level (AST), Alkaline Phosphatase level (ALP), Total Bilirubin, and Albumin 62.0±2.5, 172.5±1.0, 128±1.5, 0.80±0.05, 5.00±0.5 respectively and decreased Total protein levels (2.05±1.0). Whereas, Curcumin lowered liver enzymes 37.0±2.8, 126.12±1.5, 90.5±1.0, 0.40±0.01, 3.50±0.5 respectively, and increased levels of total protein (5.00±0.5). Group A exhibited normal liver morphology, whereas, Group B had ballooning degeneration, focal cell necrosis, and liver inflammation. Group C had moderate fatty liver but no centrilobular degeneration or focal cell necrosis and Group D exhibited minor liver inflammation and normal liver morphology. Conclusion: Curcumin was found preventative and therapeutic remedy which can be used for the treatment of hepatotoxicity. Keywords: Curcumin; Hepatotoxicity; Hepatoprotective; Isoniazid; Rifampicin

Psychiatric rating scales in Urdu: a systematic review

<p>Abstract</p> <p>Background</p> <p>Researchers setting out to conduct research employing questionnaires in non-English speaking populations need instruments that have been validated in the indigenous languages. In this study we have tried to review the literature on the status of cross-cultural and/or criterion validity of all the questionnaires measuring psychiatric symptoms available in Urdu language.</p> <p>Methods</p> <p>A search of Medline, Embase, PsycINFO and <url>http://www.pakmedinet.com</url> was conducted using the search terms; Urdu psychiatric rating scale, and Urdu and Psychiatry. References of retrieved articles were searched. Only studies describing either cross-cultural or criterion validation of a questionnaire in Urdu measuring psychiatric symptoms were included.</p> <p>Results</p> <p>Thirty two studies describing validation of 19 questionnaires were identified. Six of these questionnaires were developed indigenously in Urdu while thirteen had been translated from English. Of the six indigenous questionnaires five had had their criterion validity examined. Of the thirteen translated questionnaires only four had had both their cross-cultural and criterion validity assessed.</p> <p>Conclusion</p> <p>There is a paucity of validated questionnaires assessing psychiatric symptoms in Urdu. The BSI, SRQ and AKUADS are the questionnaires that have been most thoroughly evaluated in Urdu.</p

Specific Responses of Salmonella enterica to Tomato Varieties and Fruit Ripeness Identified by In Vivo Expression Technology

Recent outbreaks of vegetable-associated gastroenteritis suggest that enteric pathogens colonize, multiply and persist in plants for extended periods of time, eventually infecting people. Genetic and physiological pathways, by which enterics colonize plants, are still poorly understood.To better understand interactions between Salmonella enterica sv. Typhimurium and tomatoes, a gfp-tagged Salmonella promoter library was screened inside red ripe fruits. Fifty-one unique constructs that were potentially differentially regulated in tomato relative to in vitro growth were identified. The expression of a subset of these promoters was tested in planta using recombinase-based in vivo expression technology (RIVET) and fitness of the corresponding mutants was tested. Gene expression in Salmonella was affected by fruit maturity and tomato cultivar. A putative fadH promoter was upregulated most strongly in immature tomatoes. Expression of the fadH construct depended on the presence of linoleic acid, which is consistent with the reduced accumulation of this compound in mature tomato fruits. The cysB construct was activated in the fruit of cv. Hawaii 7997 (resistant to a race of Ralstonia solanacearum) more strongly than in the universally susceptible tomato cv. Bonny Best. Known Salmonella motility and animal virulence genes (hilA, flhDC, fliF and those encoded on the pSLT virulence plasmid) did not contribute significantly to fitness of the bacteria inside tomatoes, even though deletions of sirA and motA modestly increased fitness of Salmonella inside tomatoes.This study reveals the genetic basis of the interactions of Salmonella with plant hosts. Salmonella relies on a distinct set of metabolic and regulatory genes, which are differentially regulated in planta in response to host genotype and fruit maturity. This enteric pathogen colonizes tissues of tomatoes differently than plant pathogens, and relies little on its animal virulence genes for persistence within the fruit