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.     

Comparative Analysis of Ti,Ni,and Au Electrodes on Characteristics of TiO2 Nanofibers for Humidity Sensor Application

The effect of metal（Ti,Ni,and Au） electrodes on humidity sensing properties of electrospun TiO₂ nanofibers was investigated in this work.The devices were fabricated by evaporating metal contacts on SiO₂ layer thermally grown on silicon substrate.The separation between the electrodes was 90μm for all sensors.The sensors were tested from 40%to 90%relative humidity（RH） by AC electrical characterization at room temperature. When sensors are switched between 40%and 90%RH,the corresponding response and recovery time are 3 s and 5 s for Ti-electrode sensor,4 s and 7 s for Ni-electrode sensor,and 7 s and 13 s for Au-electrode sensor.The hysteresis was 3%,5%and 15%for Ti-,Ni-,and Au-electrode sensor,respectively.The sensitivity of Ti,Ni,and Au-electrode sensors are 7.53 MΩ/%RH,5.29 MΩ/%RH and 4.01 MΩ/%RH respectively at 100 Hz.Therefore Ti-electrode sensor is found to have linear response,fast response and recovery time and higher sensitivity as compared with those of Ni- and Au-electrode sensors.Comparison of humidity sensing properties of sensors with different electrode material may propose a compelling route for designing and optimizing humidity sensors.     

Performance of viscoelastic dampers (VED) under various temperatures and application of magnetorheological dampers (MRD) for seismic control of structures

A number of studies have been carried out to investigate the performance of viscoelastic dampers (VEDs) and magnetorheological dampers (MRDs) in controlling the seismic response of buildings, but very few of them regarding the effect of temperature on the behavior of those dampers. The energy absorption properties of the VEDs are dependent on the ambient temperature, excitation frequency and strain amplitude. Several mathematical models have been investigated for reproducing the experimental behavior of single degree of freedom VEDs and MEDs. Of these, only the fractional derivative model can reflect the influence of temperature which is, however, so complex that it is difficult to apply in structural analysis. In order to verify the effect of temperature, two case studies of structural element have been conducted: once using VED and once using MRD. Kelvin–Voigt mathematical model applied, they were investigated and after analyzing the results, the force vs. displacement showed that MRD achieved a high force capacity and a better performance than VED. Furthermore, the effect of the temperature in case of VED observed via plotting the dissipated energy hysteresis at different temperatures. These results validate the effect of the temperature as the lower the temperature the more viscous the dashpot element becomes, hence improving damping, but this is up to a specific low temperature.     

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.