Mechanical property characterization of a 9 mol% Ce-TZP ceramic material — I. Flexural response

Investigations were carried out on four tetragonal zirconia polycrystalline (TZP) ceramics of differing grain size containing 9 mol% CeO₂. Precision flexural tests on these materials were conducted to determine the elastic modulus, the non-linear deflection and the associated acoustic emission during such testing. The deformation was characterized in terms of the number and size of the transformation bands that developed during the non-linear response. The finest grained material initially exhibited permanent set without the presence of such bands, whereas all the coarser grained materials showed a linear relationship between the summation of the band widths and the residual deflection. The acoustic emission and plastic strain behaviour are discussed in terms of the number and size of the stress induced phase transformation bands.     

An adaptive linear combiner for on-line tracking of power systemharmonics

The paper presents a new approach for the estimation of harmonic components of a power system using a linear adaptive neuron called Adaline. The learning parameters in the proposed neural estimation algorithm are adjusted to force the error between the actual and desired outputs to satisfy a stable difference error equation. The estimator tracks the Fourier coefficients of the signal data corrupted with noise and decaying DC components very accurately. Adaptive tracking of harmonic components of a power system can easily be done using this algorithm. Several numerical tests have been conducted for the adaptive estimation of harmonic components of power system signals mixed with noise and decaying DC components     

Metastability of the Martensitic Transformation in a 12 mol% Ceria-Zirconia Alloy: II, Grinding Studies

Observations of the grinding-induced transformation in singlephase Ce-TZP materials, referred to in an earlier paper, are presented. Two techniques were used to grind the surface: by hand in a slurry of abrasive particles and with a high-speed diamond-impregnated wheel. Significant differences in X-ray diffraction profiles between the two grinding methods was observed. Limited monoclinic ZrO₂ was detected on the machineground surface, along with the reversal of the tetragonal ZrO₂ (200) peak intensities. On the hand-ground surface, considerable monoclinic phase was observed. The disappearance of the monoclinic phase with heating was followed by X-ray diffraction, and the A _f was found to exceed 700°C, while the reversal in tetragonal (200) peak symmetry and intensity remained unaltered up to at least 1000°C. Transmission electron microscope studies at various depths below the ground surface were undertaken to identify the differences between these surfaces and fractured surfaces. A simple explanation is proposed for the reversal of the tetragonal peak intensities. This reversal has previously led to the notion of a ferroelastic toughening mechanism in similar TZP materials.     

Delamination of Mg-Al Layered Double Hydroxide on Starch: Change in Structural and Thermal Properties

Mg-Al layered double hydroxide decorated starch bionanocomposites (starch/layered double hydroxide) are prepared by solution intercalation method. The bionanocomposites are systematically characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy techniques. The thermal stability of starch is enhanced due to dispersion of layered double hydroxide within the starch matrix. The chemical resistance property of starch is improved substantially with slight sacrifice in biodegradation behavior by the delamination of layered double hydroxide in starch matrix. Herein, layered double hydroxide acts as potential laminated filler for change in structural, thermal, and chemical resistance properties of starch with little sacrifice in biodegradable behavior.     

Image Steganography Using Remainder Replacement,Adaptive QVD and QVC

Wireless Personal Communications - This research article reports a steganography method based on adaptive quotient value differencing (AQVD), quotient value correlation (QVC), and remainder...     

Metasurface cavity antenna for broadband high‐gain circularly polarized radiation

The article presents a microstrip patch (MSA) fed high gain circularly polarized metasurface cavity (CP‐MSC) antenna using a planar progressively‐phased‐reflector and a transmissive linear to circular polarization conversion metascreen. The bottom metasurface reflector consists of a remodeled Jerusalem cross to obtain 2π reflection phase variation. Linear to circular polarization conversion is achieved by a hexagonal ring based meta‐element with high transmission and bellow 3 dB axial ratio from 9.5 to 10.5 GHz. Simulated and measured results of assembled CP‐MSC antenna with MSA are in good agreement. The gain of the proposed cavity antenna with 10 and 10.5 GHz MSA are 14.9 and 16.3 dBi, respectively. Below 3 dB AR throughout the operating band denotes significant circular polarization performance of the proposed antenna.     

Superior Overcurrent Protection with Motor Short-Circuit Protectors

A never ending stream of magazine articles, IEEE papers, National Electrical Code proposals and revisions attest to the need for better protection of motors, controllers, and branch circuits. Superior branch circuit overcurrent protection can be obtained by a combination of specially designed motor short-circuit protectors and especially approved motor controllers. This paper explains the protection provided and mentions test results for a range of fault currents up to a very high level.     

K R -Curve Behavior of Duplex Ceramics

The fracture toughness behavior during crack growth ( K ^R -curve behavior) of duplex ceramics is investigated. Different types of K ^R -curves can be distinguished depending on the microstructural designs of these materials which are characterized by the volume fraction and size of the dispersed pressure zones, and by their effective volume expansion. According to their K ^R -curve behavior, duplex ceramics can be subdivided into two groups consisting of "short-range" and "long-range" toughened materials. The experimental results are discussed regarding the appearance of different toughening mechanisms which are documented by crack path micrographs. An unusual toughening effect, a "crackbranching chain reaction," is documented by in situ observations. The critical stress to nucleate the observed process zone development is calculated and compared with the internal stress intensity factor K _i which has been previously proposed for these materials and with the material strength.     

Prioritizing test scenarios from UML communication and activity diagrams

Due to the large size and complexity of software, exhaustive testing becomes impossible. Hence, testing must be done in an optimized way keeping in mind factors, such as requirements of the customer, cost and time. For this, there is a need to generate test cases and exercise them to gain maximum throughput by uncovering defects. Test case/scenario prioritization is a well known and efficient technique to ensure the software quality. Prioritization of test scenarios helps in early detection of bugs. In this paper, we present an integrated approach and a prioritization technique to generate cluster-level test scenarios from UML communication and activity diagrams. In our approach, we first construct a tree representation of communication diagrams, and then a tree representation of activity diagrams. We convert them into an intermediate tree named as COMMACT tree. We, then carry out a post-order traversal of the constructed tree for selecting conditional predicates from the intermediate tree. Then, we propose an algorithm to generate test scenarios from the constructed tree. Next, the necessary information, such as method-activity sequence, associated objects, and constraint conditions is extracted from test scenario. The test sequences are a set of theoretical paths starting from initialization to end, while taking conditions (pre- and post-condition) into consideration. Each generated test sequence corresponds to a particular scenario of the considered use case. The third phase is to generate test scenarios from the tree satisfying the message–activity path test adequacy criteria. Preliminary results obtained on a case-study indicate that the technique is effective in extracting the critical scenarios from the communication and activity diagrams. Our approach generates redundant test scenarios and still achieves adequate test coverage.     

Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)

In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. [1]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H₂-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pre-growth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding.