Radar signature characterization from wind turbine scattering

textThe growth in the number of wind farms has raised significant concerns in the radar community due to their potential interference on radar systems. The motion of the turbine blades creates unwanted Doppler clutter that can interfere in the tracking of moving targets. Large turbine structures can also produce electromagnetic shadows that may make observing objects behind a wind farm difficult. Detailed characterization of the clutter is the first step towards effective mitigation techniques. The goal of this dissertation research is to gain a better understanding of the dynamic radar signatures resulting from scattering by wind turbines. First, the scattering characteristics of turbines in the presence of ground surface are studied. Image theory in conjunction with a shooting-and-bouncing ray code, Ahilo, is used to carry out the dynamic signature simulation. The observed features in the simulation are corroborated with laboratory model measurements. Second, the effects of higher order motions of a turbine undergoing rotation on the radar signatures are investigated and characterized. Mathematical models for the motions are proposed and used to simulate the joint time-frequency and inverse synthetic aperture radar characteristics of the turbine undergoing these motions. The motions are studied for an isolated turbine as well as for a turbine rotating above a ground. Selected motions are corroborated by laboratory model measurements. Next, a method to remove the dynamic clutter produced by wind turbines is presented. A physics-based basis is constructed to model the radar backscattering from a wind turbine. This basis is used in conjunction with the matching pursuit algorithm to iteratively remove the Doppler clutter due to wind turbines. The algorithm is tested using radar return generated using Ahilo. Finally, radar features of wind turbines are simulated and studied in the HF (high frequency) band. The features are presented in the range-Doppler plane for single as well as arrays of turbines. Doppler aliasing due to the limited pulse repetition frequency of HF radars is examined. Shadowing characteristics of arrays of turbines are simulated and analyzed. Electromagnetic modeling details including effects of thin-wire modeling, non-conducting turbine components, and the presence of a conducting ground surface are discussed.Electrical and Computer Engineerin

Investigation of doppler features resulting from wind turbine scattering

textThe rapid growth in the number of large wind farms has raised serious concerns about their effects on existing radar systems. The large size and rotational movement of the turbine blades can give rise to significant Doppler clutters, which interfere with the detection of moving targets such as aircraft and storms. A previous Air Force study has collected and analyzed the time-varying radar cross section resulting from the blade rotation of a single 1.5 MW turbine. However, multiple interactions taking place in a turbine were not studied in detail. Multiple interactions could play an important role in the propagation of radar signals through wind farms. This thesis sets out to more closely examine the various Doppler features resulting from the scattering due to a single turbine. Backscattered and forward scattered data are measured at Ku-band from various wind turbine models using a motorized turntable in the laboratory. The tested models include a 1:160 scale model turbine, a 3-arm wire model turbine, and a small wind turbine from Bergey Windpower with 2’ blades. The data are processed based on the short-time Fourier transform in order to relate the resulting time-varying Doppler features to various scattering mechanisms. The experimental findings are corroborated by simulations performed using the Numerical Electromagnetics Code (NEC). Furthermore, we propose a post-processing general method to reduce the intensity of the turbine scattered data. This method is applied to filter out simulated Doppler clutter from two different simulation techniques. First, the method is applied to remove the simulated Doppler clutter from the point scatterer model. Next, the algorithm is applied to simulated backscattered data generated using a high-frequency ray tracing code, Ahilo.Electrical and Computer Engineerin

Development and testing of an assessment tool for integrated learning

Objective: Development of integrated questions for undergraduate medical students and assessing students’ capability to retain and apply basic concepts in an integrated way. Method: Multiple choice questions, attempting to probe understanding and application of different concepts, affiliated with different subjects and topics, were developed. As a pilot these were administered to the students of third year and final year at the end of their certifying examinations as a mock test. The following year these questions were introduced in the continuous assessments and subsequently the certifying examinations (in third year) as 33% of the whole examination. Difficult indices, item analysis and internal consistency (alpha) were calculated for all the questions. Results: The difficulty indices of integrated questions indicated that students found the integrated questions difficult. Conclusion: There was a significant change of distribution in terms of scoring for the integrated questions. Students’ power to integrate showed reliable improvement when tested in the certifying examinations (JPMA 51:384,2001)

Satl model lesson in chemical kinetics

Studies in order to pursue kinetics and mechanism of chemical reactions are a vital component of chemical literature. SATL literature is still not available for promoting this vital aspect of chemistry teaching. A lesson pertaining to this important issue has been developed and various parameters of kinetic studies are explained therein.[AJCE, 3(1), January 2013

STR-884: EFFECT OF SPACING OF TRANSVERSE REINFORCEMENT ON THE LAPPED SPLICED GFRP‐RC COLUMNS SUBJECTED TO CYCLIC‐REVERSED LOADS

Recently, the non-corrodible fibre-reinforced polymer (FRP) materials have been used successfully as reinforcement for concrete structures. However, the behaviour of glass (G) FRP-reinforced concrete (RC) columns under seismic loading has not been explored yet. This paper presents the results of an experimental program that investigates the contribution of GFRP transverse reinforcement to the confinement of concrete core in lap-spliced GFRP-RC columns. Three full-scale column specimens were constructed and tested to failure under quasi-static cyclic‐reversed loads. All specimens were reinforced with GFRP longitudinal bars and transverse stirrups. The columns had 350-mm square cross section and 1850-mm cantilever length. Each column was cast on heavily steel-RC footing measuring 1400×1400× 600 mm3, which was constructed to simulate rotational fixity of the column and to force the failure to occur in the column. The splice length for each column was equal to sixty times the diameter of the longitudinal column reinforcement. The test variable was the spacing between the transverse GFRP reinforcement (75, 100 and 150 mm). Test results are presented in terms of mode of failure, load-drift diagrams, energy dissipation, ultimate capacity and code comparison, if applicable. The results showed that, decreasing the spacing of spiral reinforcement improved both the strength and the deformability of the columns. Moreover, the requirement of the Canadian standard for FRP-RC buildings related to the amount of confinement provided by GFRP transverse reinforcement is adequate to ensure stability of the longitudinal bars

Systemic adverse effects from inhaled corticosteroid use in asthma: a systematic review.

BACKGROUND: Oral corticosteroid use increases the risk of systemic adverse effects including osteoporosis, bone fractures, diabetes, ocular disorders and respiratory infections. We sought to understand if inhaled corticosteroid (ICS) use in asthma is also associated with increased risk of systemic effects. METHODS: MEDLINE and Embase databases were searched to identify studies that were designed to investigate ICS-related systemic adverse effects in people with asthma. Studies were grouped by outcome: bone mineral density (BMD), respiratory infection (pneumonia or mycobacterial infection), diabetes and ocular disorder (glaucoma or cataracts). Study information was extracted using the PICO checklist. Risk of bias was assessed using the Cochrane Risk of Bias tool (randomised controlled trials) and Risk of Bias In Non-randomised Studies of Interventions-I tool (observational studies). A narrative synthesis was carried out due to the low number of studies reporting each outcome. RESULTS: Thirteen studies met the inclusion criteria, 2 trials and 11 observational studies. Study numbers by outcome were: six BMD, six respiratory infections (four pneumonia, one tuberculosis (TB), one non-TB mycobacteria), one ocular disorder (cataracts) and no diabetes. BMD studies found conflicting results (three found loss of BMD and three found no loss), but were limited by study size, short follow-up and lack of generalisability. Studies addressing infection risk generally found positive associations but suffered from a lack of power, misclassification and selection bias. The one study which assessed ocular disorders found an increased risk of cataracts. Most studies were not able to fully adjust for known confounders, including oral corticosteroids. CONCLUSION: There is a paucity of studies assessing systemic adverse effects associated with ICS use in asthma. Those studies that have been carried out present conflicting findings and are limited by multiple biases and residual confounding. Further appropriately designed studies are needed to quantify the magnitude of the risk for ICS-related systemic effects in people with asthma

MicroRNA profiling of tomato leaf curl new delhi virus (tolcndv) infected tomato leaves indicates that deregulation of mir159/319 and mir172 might be linked with leaf curl disease

Background: Tomato leaf curl virus (ToLCV), a constituent of the genus Begomovirus, infects tomato and other plants with a hallmark disease symptom of upward leaf curling. Since microRNAs (miRs) are known to control plants developmental processes, we evaluated the roles of miRNAs in Tomato leaf curl New Delhi virus (ToLCNDV) induced leaf curling. Results: Microarray analyses of miRNAs, isolated from the leaves of both healthy and ToLCNDV agroinfected tomato cv Pusa Ruby, revealed that ToLCNDV infection significantly deregulated various miRNAs representing ~13 different conserved families (e.g., miR319, miR172, etc.). The precursors of these miRNAs showed similar deregulated patterns, indicating that the transcription regulation of respective miRNA genes was perhaps the cause of deregulation. The expression levels of the miRNA-targeted genes were antagonistic with respect to the amount of corresponding miRNA. Such deregulation was tissue-specific in nature as no analogous misexpression was found in flowers. The accumulation of miR159/319 and miR172 was observed to increase with the days post inoculation (dpi) of ToLCNDV agroinfection in tomato cv Pusa Ruby. Similarly, these miRs were also induced in ToLCNDV agroinfected tomato cv JK Asha and chilli plants, both exhibiting leaf curl symptoms. Our results indicate that miR159/319 and miR172 might be associated with leaf curl symptoms. This report raises the possibility of using miRNA(s) as potential signature molecules for ToLCNDV infection. Conclusions: The expression of several host miRNAs is affected in response to viral infection. The levels of the corresponding pre-miRs and the predicted targets were also deregulated. This change in miRNA expression levels was specific to leaf tissues and observed to be associated with disease progression. Thus, certain host miRs are likely indicator of viral infection and could be potentially employed to develop viral resistance strategies

Respiratory arrest in a child after flushing of pancuronium from the dead space of intravenous cannula

It is common practice for patients admitted to Intensive Care Units to have indwelling intravenous cannulae. Sometimes these cannulae are used only for the administration of drugs and are closed otherwise. Residual drugs in the deadspace of these intravenous cannulae as well as connected stoppers or 3-way stopcocks can later be flushed unknowingly. We would like to report a case in which inadvertent flushing of residual pancuronium caused complete muscle paralysis and respiratory arrest in a young child

Validated High Performance Liquid Chromatography Method for Analysis of Cefadroxil Monohydrate in Human Plasma

Purpose: To develop a simple, rapid and sensitive high performance liquid chromatography (HPLC) method for the determination of cefadroxil monohydrate in human plasma.Methods: Schimadzu HPLC with LC solution software was used with Waters Spherisorb, C18 (5 μm, 150mm × 4.5mm) column. The mobile phase was sodium dihydrogen phosphate buffer pH 4.0 and methanol in a ratio of 96:4. Flow rate was 1.5 ml/min and injection volume was 100 μl. Peak response was detected at 260 nm.Results: System suitability results revealed that the coefficient of variation (CV) for retention time, peak response, tailing factor and resolution of six replicate injections was < 3 %. The method was selective to determine cefadroxil in plasma because there was no peak interference of plasma with cefadroxil at its retention time (7.792 min). Linearity was in the range of 0.5 - 30 μg/ml with slope and intercept of 41694.53 and 22614.87, respectively (R2 = 0.9953). Limit of detection (LOD) and lower limit of quantification (LLOQ) of the method were 0.03 and 0.06 μg/ml, respectively. Absolute recovery of cefadroxil from plasma was in the range 71 - 90.4 %, while inter-day and intra-day analysis showed satisfactory precision and accuracy; thus, the method was reproducible with the range of CV, i.e., 0.35 - 4.01 and 1.88 - 7.9 % for interday and intraday precision, respectively.Conclusion: The developed method being simple, rapid, reproducible can be suitably employed in pharmacokinetic and bioequivalence studies of cefadroxil monohydrate.Keywords: Validation, Cefadroxil monohydrate, Human plasma, Pharmacokinetics Bioequivalenc