Effects of expanded vermiculite on the properties of fired bricks from water treatment sludge

In the present study, the suitability of using water treatment sludge (WTS) as the main raw material and expanded vermiculite (EV) as aggregate in the production of fired bricks was investigated. Mixtures containing between 75%–100% WTS by weight (wt.) and 5%–25% EV by wt. were prepared at various proportions. The mixtures were compressed under 40 MPa pressure and fired at 1000°C. It was found the incorporation of EV in fired bricks resulted in a decrease in thermal conductivity, compressive strength, and bulk density and an increase in apparent porosity and water absorption. For the addition of 5%–25% EV by wt., bulk density ranged between 2.01 and 1.69 kg/m³, compressive strength 19.3 and 8.3 MPa, water absorption 21.1% and 10.1%, and thermal conductivity 0.678 and 0.374 W/m-K, respectively. Based on the promising physical and mechanical properties, fired bricks incorporating WTS and EV can potentially offer an alternative to the traditional production of clay bricks while adhering to the principle of a circular economy.     

High robustness of an SR motor angle estimation algorithm usingfuzzy predictive filters and heuristic knowledge-based rules

In this paper, the operation of a fuzzy predictive filter used to provide high robustness against feedback signal noise in a fuzzy logic (FL)-based angle estimation algorithm for the switched reluctance motor is described. The fuzzy predictive filtering method combines both FL-based time-series prediction, as well as a heuristic knowledge-based algorithm to detect and discard feedback signal error. As it is predictive in nature, the scheme does not introduce any delay or phase shift in the feedback signals, In addition, the fuzzy predictive filter does not require any mathematical modeling of the noise and, therefore, can be used effectively to control nonGaussian impulsive-type noise. An analysis of the noise and error commonly found in practical motor drives is given, and how this can effect position estimation. It is shown using experimental results that the FL-based scheme can cope well with erroneous and noisy feedback signals     

High robustness and reliability of fuzzy logic based positionestimation for sensorless switched reluctance motor drives

In many applications where motor drives are used, concern. Thus, a major consideration is the reliability of position estimation schemes when sensor less SR motor drive control is employed. Hence, in this paper, the robust of a fuzzy logic based angle estimation algorithm for the switched reluctance motor (SR) motor is described. It is shown using theoretical analysis and experimental results, that by using logic, the angle estimation scheme gains a high level of robustness and reliability. A theoretical and quantitative analysis of the noise and error commonly found in practical motor drives is given, and how this can affect SR motor position estimation. An analysis is also given on the concepts of robustness and reliability. It is shown that the fuzzy logic based scheme is robust to erroneous and noisy signals commonly found in motor drives     

Synthesis and characterization of conducting copolymer of Trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene with EDOT

Ferrocene‐substituted conducting polymer namely poly(trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene‐co‐3,4‐ethylenedioxythiophene) [P(MTFE‐co‐EDOT)] was synthesized and its electrochromic properties were studied. Monomer, MTFE, was obtained using 2‐(ferrocenyl)ethene and 3‐methyl‐4‐bromothiophene. The structure of monomer was determined via Fourier transform infrared spectroscopy (FTIR), ¹H‐NMR, and ¹³C‐NMR techniques. The copolymer was synthesized using this monomer and EDOT. The resulting copolymer P(MTFE‐co‐EDOT) was characterized by cyclic voltammetry, FTIR, scanning electron microscopy, atomic force microscopy, and UV–vis spectroscopy. The conductivity measurements of copolymer and PEDOT were accomplished by the four‐probe technique. Although poly(trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene) [P(MTFE)] reveals no electrochromic activity, its copolymer with EDOT has two different colors (violet and gray). Band gap (E_g) and λ_max of P(MTFE‐co‐EDOT) were determined. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Graphene-enabled silver nanoantenna sensors

Silver is the ideal material for plasmonics because of its low loss at optical frequencies but is often replaced by a more lossy metal, gold. This is because of silver's tendency to tarnish and roughen, forming Ag(2)S on its surface, dramatically diminishing optical properties and rendering it unreliable for applications. By passivating the surface of silver nanostructures with monolayer graphene, atmospheric sulfur containing compounds are unable to penetrate the graphene to degrade the surface of the silver. Preventing this sulfidation eliminates the increased material damping and scattering losses originating from the unintentional Ag(2)S layer. Because it is atomically thin, graphene does not interfere with the ability of localized surface plasmons to interact with the environment in sensing applications. Furthermore, after 30 days graphene-passivated silver (Ag-Gr) nanoantennas exhibit a 2600% higher sensitivity over that of bare Ag nanoantennas and 2 orders of magnitude improvement in peak width endurance. By employing graphene in this manner, the excellent optical properties and large spectral range of silver can be functionally utilized in a variety of nanoscale plasmonic devices and applications.     

Variational Basis of Nonlinear Flexibility Methods for Structural Analysis of Frames

There have been a number of contributions to the literature on a class of structural analysis methods referred to as nonlinear flexibility methods. These methods appear to perform very well compared to classical stiffness approaches for problems with constitutive nonlinearities. Although most of these methods appeal to variational principles, the exact variational basis of these methods has not been entirely clear. Some of them even seem not to be variationally consistent. We show in this paper that, because the equations of equilibrium and kinematics are directly integrable, a nonlinear flexibility method (in the spirit of those presented in the literature) can be derived without appeal to variational principles. The method does not involve interpolation of the displacement field and the accuracy of the method is limited only by the numerical scheme used to perform element integrals. There is no need for h refinement to improve accuracy. Further, we show that this nonlinear flexibility method is essentially identical, with some subtle algorithmic differences, to a two-field (Hellinger-Reissner) variational principle when the stress interpolation is exact (which is possible for this class of problems). We demonstrate the utility of the nonlinear flexibility method by applying it to a problem involving cyclic inelastic loading wherein the strain fields evolve into functions that are difficult to capture through interpolation.     

Investigation of inverterless control of interior permanent-magnet alternators

This paper investigates the performance and control of a low-cost 6-kW concept demonstrator of an "inverterless" automotive alternator. This is based on a switched-mode rectifier (SMR) combined with a high-flux interior permanent-magnet (PM) machine. Duty cycle control of the SMR is described and the theoretical predictions are compared with open-loop experimental results. The efficiency of the concept demonstrator is examined as a function of speed and load. Control issues regarding automotive operation are discussed.     

Modeling of MOSFET parasitic capacitances, and their impact on circuit performance

We study layout dependent, parasitic capacitance contributions of MOSFETs with 3D simulations, and show that these contributions are for narrow and short devices comparable to intrinsic contributions. The performance of 65-nm technology is strongly affected by these components, and should therefore be modeled accurately in circuit simulations. We propose a methodology how to accurately and consistently model them in a design flow. The methodology is validated with ring oscillator measurements.     

Permittivity determination of liquid materials using waveguide measurements for industrial applications

There is a need for a simple and relatively inexpensive microwave method for complex permittivity, ?, determination of liquid materials in industrial applications. Measurement cables that connect the measurement cell to the measuring instrument (usually a vector network analyser) may be either subject to severe phase instability particularly if they are long or metrology-grade cables are not available, or subject to thermal variation. In these instances, calibration techniques based on complex scattering parameter measurements may drastically suffer from extension of the reference plane to the boundaries of the measurement cell or sample end surfaces. In such situations, amplitude-only methods based on simplified calibration techniques such as response calibration are appropriate and very feasible. These methods have applications in industry such as thickness measurement and disbonding and delamination detection. The motivation of this study is to investigate a suitable method for ? determination of liquid materials using amplitude-only waveguide measurements. The analysis is restricted to lossy dielectric materials, which possess large enough attenuation such that the multiple reflections between their two end surfaces can be neglected. We derived an equation in terms of the loss tangent of these materials for selecting a suitable material thickness. We presented two approximations (frequency-independent and power-series representation) for ? determination of these materials. For validation of the method, we measured the ? of methanol and commercially available antifreeze solution by our method using a simple (frequency response) calibration and by another waveguide method using the thru-reflect-line calibration.