Vibration characteristics of FGM circular cylindrical shells using wave propagation approach

In this paper, the wave propagation approach is employed to study the vibration characteristics of functionally graded material circular cylindrical shells. Axial modal dependence is approximated by exponential functions. This is a very simple and easily applicable technique. This avoids a large amount of algebraic manipulations. A theoretical analysis of shell natural frequencies are conducted for various boundary conditions. Validity and accuracy of the present method are confirmed by comparing the present results with those available in the literature. A good agreement is observed between the two sets of the results.     

Prediction of in-service microstructural degradation of A106 steel using eddy current technique

In-service microstructural degradation of ASTM A106 steel occurs by the spheroidising and coarsening of pearlite. The specimens of the A106 have been exposed at 710 °C for different durations to simulate service conditions. The resultant pearlite coarsening was evaluated by measuring eddy current inductive reactance and resistance; phase angles were measured using these values and compared with results of optical microscopy, image analysis and resistivity measurements. It was observed that the eddy current phase angle has a linear relation with pearlite variations. It can further be used for in-situ eddy current evaluation of microstructural degradation of pipes or steel vessels. A mathematical model has been proposed to assist such field investigations.     

Immobilization of Trichoderma viride for enhanced methylene blue biosorption: Batch and column studies

An efficient dye biosorbent was developed by entrapping a fungus mold, Trichoderma viride, within loofa sponge (LS) matirx. Immobilization enhanced the sorption of dye by 30% at equilibrium as compared with T. viride free biomass (TVFB). The maximum dye biosorption capacity of T. viride immobilized onto loofa sponge (TVILS) and TVFB was found to be 201.52 and 155.06 mg g⁻¹ biomass, respectively. The kinetics of dye removal by TVILS was rapid, with 84.3% sorption within the first 30 min and equilibrium after 90 min, whereas sorption by TVFB was slower as 61.4% dye was removed in first 30 min and equilibrium was achieved in 120 min. Biosorption kinetics and equilibria followed the pseudo-second-order and Langmuir adsorption models. FTIR spectroscopy of T. viride biomass showed that amine, hydroxyl, carbonyl and amide bonds were involved in the sorption of dye. Dye desorption from dye-laden TVILS with 0.1 M HCl was 99%. Regenerated TVILS was reusable without any appreciable decrease in its biosorption capacity during five repeated cycles. The dye removing capacity of TVILS in a continuous-flow column bioreactor was better than in batch-scale procedures. The study shows that TVILS has the potential of application as an efficient biosorbent for the removal of methylene blue from aqueous solutions.     

Intermediate state of hexagonal close-packed structure to face-centered cubic structure transformation:Direct evidence for basal-type face-centered cubic phase via partial dislocation in zirconium

1.Introduction Zirconium(Zr)and its alloys show great applications in nu-clear and chemical industry thanks to their appropriate me-chanical properties,low ther...     

Comment on 'Active simulation of grounded inductors with CCII+ s and grounded passive elements'

This comment shows that circuits for active simulation of grounded inductors with plus-type second-generation current-conveyors (CCII + s) and grounded passive elements can be systematically derived from Sedra-Smith gyrator realization. In addition to the available realizations, new circuit topologies are presented. Some of the new topologies can yield inductance forms which are not realizable using the available topologies. Also, a new topology for realizing pure inductance without recourse to element matching conditions is presented.     

Large signal analysis of the SiGe HBT translinear harmonic mixer

Analytical expressions are obtained for the amplitudes of the desired output components of a SiGe translinear harmonic mixer excited by large-amplitude local oscillator and radio-frequency signals. Comparison with previously published calculated and simulated results is included.     

Comparison of alteplase (tissue plasminogen activator) high‐dose vs. low‐dose protocol in restoring hemodialysis catheter function: The ALTE‐DOSE study

Hemodialysis catheter (HDC) dysfunction due to thrombosis is common, and dysfunction incidence can reach up to 50% within 1 year of use. Although administration of intraluminal alteplase (tissue plasminogen activator [tPA]) is the standard of practice to pharmacologically restore HDC function, there are no evidence‐based guidelines concerning the optimal tPA dose. The purpose of this study was to compare the efficacy of 1.0‐mg vs. 2.0‐mg tPA dwell protocols in restoring the HDC function in thrombotic dysfunctional catheters. A retrospective, single‐center study was conducted on two independent cohorts of patients; the first (n = 129) received 2.0 mg tPA/catheter lumen, while the second (n = 108) received 1.0 mg tPA/catheter lumen. Kaplan–Meier and Cox regression analyses were performed to compare the catheter survival time between patients who received 1.0 mg tPA and those who received 2.0 mg tPA. Catheter removal occurred in 25 (19.4%) of those catheters treated with 1.0 mg tPA compared with 11 (10.2%) of catheters treated with 2.0 mg tPA (P = 0.05). The hazard ratio (HR) for catheter removal was 2.75 (95% confidence interval [^95%CI] = 1.25–6.04) for the 1.0‐mg tPA cohort compared with the 2.0‐mg tPA cohort. Correction added on 3 December 2012, after first online publication: The tPA cohort values were changed. Female gender (HR = 2.51; ^95%CI = 1.20–5.27) and age (HR = 0.96; ^95%CI = 0.94–0.98) were also associated with catheter survival. Our findings suggest that treatment of dysfunctional HDC with 2.0‐mg tPA dwells is superior to 1.0‐mg tPA dwells.     

Beyond network simulators: Fostering novel distributed applications and protocols through extendible design

Simulation has been of paramount importance to the development of novel Internet protocols. Such an approach typically focuses on one of three domains: wireless and other link-layer technologies, routing protocols, and transport-layer mechanisms and protocols. Existing techniques can tackle well simulation at layers 2, 3 and 4 of the TCP/IP architecture, but are not flexible enough to appropriately deal with application-layer protocols. These require simulators that support the modeling of networks and components with different levels of abstraction. Simmcast is an object-oriented framework that focuses on the necessary flexibility for application-layer protocol research. A simulation can be developed by the simple extension of building blocks that closely resemble components of a real network such as hosts, links and routers. The internal complexity of these components, however, is hidden from the user, so he/she can focus on the implementation of the desired protocol characteristics. This paper describes the flexible simulation architecture proposed and instantiated through Simmcast, and draws lessons from our experience in designing, implementing and deploying it. We also present framework instances used to evaluate application-layer protocols, exemplifying how different kinds of simulations can be developed with Simmcast.     

Formalizing a hierarchical file system

An abstract file system is defined here as a partial function from (absolute) paths to data. Such a file system determines the set of valid paths. It allows the file system to be read and written at a valid path, and it allows the system to be modified by the Unix operations for creation, removal, and moving of files and directories. We present abstract definitions (axioms) for these operations. This specification is refined towards a pointer implementation. The challenge is to have a natural abstraction function from the implementation to the specification, to define operations on the concrete store that behave exactly in the same way as the corresponding functions on the abstract store, and to prove these facts. To mitigate the problems attached to partial functions, we do this in two steps: first a refinement towards a pointer implementation with total functions, followed by one that allows partial functions. These two refinements are proved correct by means of a number of invariants. Indeed, the insights gained consist, on the one hand, of the invariants of the pointer implementation that are needed for the refinement functions, and on the other hand of the precise enabling conditions of the operations on the different levels of abstraction. Each of the three specification levels is enriched with a permission system for reading, writing, or executing, and the refinement relations between these permission systems are explored. Files and directories are distinguished from the outset, but this rarely affects our part of the specifications. All results have been verified with the proof assistant PVS, in particular, that the invariants are preserved by the operations, and that, where the invariants hold, the operations commute with the refinement functions.