On Internal Fracture of Solids

Initiation and propagation of internal fracture in solid

Fault tolerant motor drive system with redundancy for critical applications

Some of the recent research activities in the area of electric motor drives for critical applications (such as aerospace and nuclear power plants) are focused on looking at various motor and drive topologies. This paper presents a motor drive system, which provides an inverter topology for three-phase motors, and also proposes an increased redundancy. The paper develops a simulation model for the complete drive system including synthetic faults. In addition, the hardware details including the implementation of DSP based motor controller, inverter module, and brushless PM motor system are provided and some experimental results are presented.N. Ertugrul, W. Soong, G. Dostal and D. Saxo

Analysis and design of energy storage for current-source 1-ph Grid-connected PV inverters

Copyright © 2008 IEEEThis paper examines the analysis and design of a DC link inductor for a current source 1-ph grid-connected photovoltaic (PV) inverter. Firstly the effect of voltage or current ripple on the PV array average output power is examined using a normalized PV output characteristic. Secondly the design of the inductor and in particular the trade-off between the PV array output power loss and the inductor copper loss are discussed. An inductor was built and a comparison of the calculated and measured loss breakdown is presented.G. Ertasgin, D.M. Whaley, N. Ertugrul and W.L. Soon

Analysis and performance evaluation of an axial-field brushless PM machine utilising soft magnetic composites

Copyright © 2007 IEEEOne of the major research activities in electric machines involves the use of alternative magnetic materials. Soft magnetic composites (SMC) offer the advantages of 3D magnetic flux paths and low-cost manufacturing. This paper examines the analysis and modelling of a prototype axial-field permanent magnet machine which uses SMC. Measured parameters and performance with an inverter is compared to 3D finite-element simulations. © 2007 IEEE

Validating a methodology to measure frailty syndromes at hospital level utilising administrative data.

BACKGROUND: Identifying older people with clinical frailty, reliably and at scale, is a research priority. We measured frailty in older people using a novel methodology coding frailty syndromes on routinely collected administrative data, developed on a national English secondary care population, and explored its performance of predicting inpatient mortality and long length of stay at a single acute hospital. METHODOLOGY: We included patient spells from Secondary User Service (SUS) data for those ≥65 years with attendance to the emergency department or admission to West Middlesex University Hospital between 01 July 2016 to 01 July 2017. We created eight groups of frailty syndromes using diagnostic coding groups. We used descriptive statistics and logistic regression to explore performance of diagnostic coding groups for the above outcomes. RESULTS: We included 17,199 patient episodes in the analysis. There was at least one frailty syndrome present in 7,004 (40.7%) patient episodes. The resultant model had moderate discrimination for inpatient mortality (area under the receiver operating characteristic curve (AUC) 0.74; 95% confidence interval (CI) 0.72-0.76) and upper quartile length of stay (AUC 0.731; 95% CI 0.722-0.741). There was good negative predictive value for inpatient mortality (98.1%). CONCLUSIONS: Coded frailty syndromes significantly predict outcomes. Model diagnostics suggest the model could be used for screening of elderly patients to optimise their care

Bacterial neuraminidase facilitates mucosal infection by participating in biofilm production

Many respiratory pathogens, including Hemophilus influenzae, Streptococcus pneumoniae, and Pseudomonas aeruginosa, express neuraminidases that can cleave α2,3-linked sialic acids from glycoconjugates. As mucosal surfaces are heavily sialylated, neuraminidases have been thought to modify epithelial cells by exposing potential bacterial receptors. However, in contrast to neuraminidase produced by the influenza virus, a role for bacterial neuraminidase in pathogenesis has not yet been clearly established. We constructed a mutant of P. aeruginosa PAO1 by deleting the PA2794 neuraminidase locus (Δ2794) and tested its virulence and immunostimulatory capabilities in a mouse model of infection. Although fully virulent when introduced i.p., the Δ2794 mutant was unable to establish respiratory infection by i.n. inoculation. The inability to colonize the respiratory tract correlated with diminished production of biofilm, as assessed by scanning electron microscopy and in vitro assays. The importance of neuraminidase in biofilm production was further demonstrated by showing that viral neuraminidase inhibitors in clinical use blocked P. aeruginosa biofilm production in vitro as well. The P. aeruginosa neuraminidase has a key role in the initial stages of pulmonary infection by targeting bacterial glycoconjugates and contributing to the formation of biofilm. Inhibiting bacterial neuraminidases could provide a novel mechanism to prevent bacterial pneumonia

Novel high-speed induction motor for a commercial centrifugal compressor

Copyright © 2000 IEEEThis paper describes the electrical, mechanical, and metallurgical design, construction, and testing of a novel low-cost high-speed high-efficiency induction motor to drive a new type of small centrifugal compressor in industrial cooling applications. The 28-shaft-hp 50-kr/min motor features a unique laminated rotor with a multifunction high-strength copper-alloy cage brazed with a novel process. Relatively thin high-silicon steel laminations were used to achieve low losses and high mechanical strength at low cost. Different heat treatments for the stator and rotor laminations were used to optimize the mechanical and magnetic properties. The preprototype motors achieved about 94% (electromagnetic) efficiency at the rated point, including inverter harmonics, while meeting cost (less than one-tenth of aerospace practice) and produceability goals.Wen L. Soong, Gerald B. Kliman, Roger N. Johnson, Raymond A. White, and Joseph E. Mille

Estimation of PM Machine Efficiency Maps from Limited Data

This article investigates the accuracy of the estimation of efficiency maps for permanent magnet (PM) machines using the stator resistance, d- and q-axis flux-linkages versus the corresponding axis current and the iron loss versus the speed characteristic. The ultimate goal is to apply this approach to the experimental measurements, but this article performs initial investigation using only the finite-element (FE) data. Detailed FE data for 50-kW surface PM (SPM) and interior PM (IPM) machines are used to determine the 'actual' or exact efficiency map and, hence, the accuracy of using approximations. This article examines the effect on the torque-speed capability curve when ignoring cross-saturation effects. It also examines the modeling of the variation of iron losses as a function of load in the constant torque and power regions. A novel approach based on scaling the no-load (NL) losses as a function of load is proposed and shown to give promising results. FE results from two other machines are also provided, which show good correspondence

Bank Erosion Survey of the Illinois River, Volume 2: Appendices

"December 2000."This report summarizes the research and surveying that were conducted in 1995 to determine the amount and severity of bank erosion that existed on the entire length of the Illinois River. The study reach extended from Grafton, River Mile (RM) 0 to Joliet, RM 286