Failure Analysis of a Composite Rudder Stock Using 3D X-ray Microcomputed Tomography

Journal of Failure Analysis and Prevention - A failure analysis investigation was performed on the remnants of a carbon fiber rudder stock that fractured during operation on a vessel in an offshore...     

Inability to start hemodialysis after a smooth temporary hemodialysis catheter insertion procedure

Cannulation of the central vein for placement of the temporary dual-lumen catheter for hemodialysis can usually be safely and reliably performed under ultrasonographic guidance. Here, we report a case of aberrant catheter entry into the internal thoracic vein during an apparently smooth procedure. The value of sonographic guidance, together with fluoroscopy with or without venography, will be discussed.     

BIST/Digital-Compatible Testing of RF Devices Using Distortion Model Fitting

Testing of Radio Frequency (RF) circuits for nonlinearity specifications generally requires the use of multiple test measurements thereby contributing to increased test cost. Prior RF test methods have suffered from significant test calibration effort (training for supervised learners) when using compact tests or from increased test time due to direct specification measurement. On the other hand, due to aggressive technology scaling, there are plenty of digital transistors available that can be used to simplify testing of Analog/Mixed-Signal (AMS) and RF devices. In this paper, an RF test methodology is developed that: (a) allows RF devices to be tested for several distortion specifications using distortion model fitting algorithms in test time comparable to what can be achieved using supervised learning techniques while retaining the accuracy of direct specification measurement, (b) allows multiple RF specifications to be determined concurrently from a single data acquisition and (c) allows digital-compatible testing/BIST to be performed using digital testers or on-chip built in self-test (BIST) circuitry. With regard to (a), a key benefit is that no training of supervised learning algorithm is necessary. The proposed method based on distortion model fitting is shown to give excellent results across common RF performance metrics while providing ~10× improvements in test time compared to previous methods.     

An improved version of modified Liu–Michel's criterion for global asymptotic stability of fixed-point state-space digital filters using saturation arithmetic

A greatly relaxed version of modified Liu–Michel's criterion (due to Singh) for the global asymptotic stability of fixed-point state-space digital filters with saturation arithmetic is presented.     

Modification of non‐Newtonian flow behavior of aqueous solution of poly(vinyl alcohol) by conducting polypyrrole prepared by in situ polymerization of pyrrole

The rheological behavior of an aqueous solution of poly(vinyl alcohol) (PVA) and polypyrrole (PPY) dispersions prepared by ferric chloride (FeCl₃)‐catalyzed polymerization of pyrrole was investigated at 12°C using a coaxial rotational viscometer. The results show that the addition of a low dose of FeCl₃ to the PVA solution greatly influences its rheology. The prominent shear‐thickening (dilatant) nature of PVA turns significantly pseudoplastic (shear thinning) in the presence of FeCl₃. Polypyrrole‐loaded PVA was obtained in a stable, optically clear dispersion by in situ polymerization of pyrrole in an aqueous PVA solution (5%) using FeCl₃ as the oxidative catalyst at 12°C. The PPY dispersions in aqueous PVA systems having a low loading of PPY and low Fe⁺³ content retain the dilatant character of an aqueous PVA solution; however, for an aqueous PVA system having a relatively high PPY loading and also a high Fe⁺³ content, prominent pseudoplastic (shear thinning) behavior is exhibited. The odd novel rheological patterns exhibited by a PVA solution in the absence and presence of FeCl₃ and the PVA–PPY dispersions containing FeCl₃ under different sets of conditions are explained on the basis of the complexation of PVA by Fe⁺³ and related ions and also as a consequence of some degree of H‐bonding and chemical grafting between the support polymer PVA and the PPY formed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3737–3741, 2004     

Study of polyaniline polyacrylamide composites by positron annihilation technique

Polyaniline doped with nonoxidizing Bronsted acids is recognized as a conducting material, as its electrical conductivity changes with percentage of doping. In the present work, different percentages of doped polyaniline were blended with polyacrylamide and their electrical conductivities as well as the positron annihilation lifetimes were measured. Analysis of data yielded three lifetime components. It was observed that the value of the short lifetime component remained constant for doping concentration, whereas that of the intermediate component τ₂ decreased. The relative intensity pertaining to τ₂, however, increased with the increase in doped PANI concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 930–933, 2003     

Conducting blends of poly(o‐toluidine) and ethylene–propylene–diene terpolymer

Poly(o‐toluidine) (POT) is an electroactive polymer with poor mechanical and thermal characteristics. We examined the scope for improving such properties by making blends of POT with ethylene–propylene–diene rubber (EPDM). We prepared POT–EPDM blends containing different weight fractions of POT by intimately mixing known volumes of separate solutions of the two polymers (POT in THF and EPDM in toluene). Films of EPDM and POT–EPDM blends in solution were obtained by spreading, solvent evaporation, and film casting techniques. POT, EPDM, and their blends were characterized in solution by ultraviolet‐visible spectroscopy, and the respective dried samples were analyzed by Fourier transform infrared spectroscopy and thermogravimetry. The polymer samples were further analyzed morphologically by scanning electron microscopy, and their tensile strengths were also evaluated. Spectroscopic and thermal studies of the blends indicated some sort of interaction between the two constituent polymers. The direct current electrical conductivity of the blends in increasing order of POT loading (12.5–100%) was in the range 9.9 × 10^?5 to 11.6 × 10^?2 S cm^?1. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2550–2555, 2003     

Studies of extraction of methylene blue from synthetic waste water using liquid emulsion membrane technology

A comprehensive study pertaining to liquid emulsion membrane (LEM) extraction process of methylene blue from wastewater is presented. The liquid membrane is made of an emulsifying agent (Monumal 80) with various organic diluents. Surfactant (5 wt%) (Monumal 80) and kerosene gave good extraction. Important variables affecting LEM permeation process include stability of membrane, contact time of extraction, strip phase concentration, treat ratio (strip phase: organic phase), stirring speed, feed phase concentration were systematically studied for percentage of extraction by LEM. Kerosene as diluent gave 99.57% extraction with NaOH as strip phase. © 2012 Canadian Society for Chemical Engineering