Transition metal modified bulk BiFeO3 with improved magnetization and linear magneto-electric coupling

At present BiFeO₃ (BFO) is the most attractive and sole example, which possesses low magnetization value, high leakage current and low polarization in ceramic form. Single-phase room temperature multiferroics are rare in nature. This paper deals with the improved magnetic and observed linear magneto-electric coupling in Co and Sm co-doped BiFeO₃ ceramics synthesized by sol-gel process at low temperature ∼600 °C. As synthesized Bi_0.9Sm_0.10Fe_0.95Co_0.05O₃ (BSFCO) showed high impurities phases (20%) over wide range of calcination temperatures. Impurity phases reduced drastically from 20% to 5% after leaching with nitric acid. However the electrical and the magnetic properties were almost the same for both phases. Well-defined magnetic hysteresis with high magnetic moment was found at room temperature. Ferroelectric polarization studies demonstrated similar values and shape as reported in literature for the pure bulk BFO. Linear magneto-electric (ME) coupling and weak ME coefficient (α) ∼ 0.6 e−10 s m⁻¹ were observed in the co-doped BFO. The origin of the strong ferromagnetic property in our samples may be due to the presence of rare earth and transition metal ions at the lattice sites of BFO or due to impurity phase, since we have not seen any change in magnetization with reduction of impurity phase the later effect is more unlikely.     

Spontaneous hemobilia in a hemophiliac treated by factor VIII replacement and nasobiliary drainage

We report a case of spontaneous hemobilia in a hemophilia patient presenting with classical Sandblom's triad of symptoms. Endoscopic retrograde cholangiography was helpful in establishing the diagnosis. Hemobilia subsided with factor VIII replacement and endoscopic nasobiliary drainage. Endoscopic nasobiliary drainage resulted in lysis of the clots in the biliary tree and relief of obstructive jaundice.     

Thermal Compatibility and Durability of Wearing Surfaces on GFRP Bridge Decks

The paper investigates thermal compatibility between wearing surface (WS) materials and glass fiber reinforced polymer (GFRP) bridge decks, and proposes a more durable hybrid WS system for GFRP decks. Wearing surface delamination problems observed on many existing GFRP bridge decks motivated the investigation and the search for a durable WS material that could alleviate the problems. Several WS materials were bonded to GFRP panels, with and without surface preparation, and tested under various environmental conditions. In addition to the standard ASTM C884 method, the testing program included two new methods for thermal compatibility testing to reflect the in-service conditions of WSs on GFRP bridge decks. The proposed methods were developed to account for the influence of freeze–thaw–heat and submerge–freeze cycles on thermal compatibility and durability. The investigation concluded that a hybrid WS system, consisting of two-layered WS materials, has the best bond quality. Applied directly on top of a GFRP deck, the top layer of the hybrid WS system had the best tire resistance, forming a nonskid riding surface.     

Ritz-Based Static Analysis Method for Fiber Reinforced Plastic Rib Core Skew Bridge Superstructure

A Ritz-based static analysis procedure is described for fiber-reinforced plastic, skew bridge superstructure, or deck, with a parallel grid core. This is a simplified analysis method based on a transformed plate formulation and the classical Ritz method. The rib core bridge superstructure, or deck, is idealized as a homogeneous, orthotropic skew plate to which the Ritz method is applied to discretize the resultant, equivalent orthotropic skew plate. Three laminated skew plate examples are presented; the results are compared with finite-element solution to verify the validity of the simplified method. A practical demonstration of a rib core skew bridge superstructure is investigated using the simplified method. The procedure provides a useful analysis tool that can be used in the preliminary design stage without the use of finite-element analysis.     

Influence of spinel substrate and over-layer for enhanced SAW and AO properties with KNbO3 thin film

Surface acoustic wave (SAW) propagation characteristics have been studied using modeling calculations for a potassium niobate (KNbO/sub 3/) thin film-layered structure with [001] and [110] orientation on a single crystal spinel (MgAl/sub 2/O/sub 4/) substrate, and a spinel buffer layer on silicon. Variation in the electromechanical coupling and acoustic attenuation has been compared. A significantly high value of coupling factor (k/sub max//sup 2/=23%) is obtained for the [001]KNbO/sub 3//spinel structure by introducing an optimum thickness of spinel over-layer for potential wide bandwidth SAW device applications. The dispersion characteristics with the [110] KNbO/sub 3/ orientation indicate an initial peak in the coupling coefficient value (k/sub max//sup 2/=8.8%) at a relatively low KNbO/sub 3/ film thickness that appears attractive for fabricating devices with thinner films. The KNbO/sub 3/ film with [001] orientation is found attractive for efficient acousto-optic (AO) device application with the formation of a symmetric waveguide structure (spinel(0.5 /spl mu/m)/KNbO/sub 3/(1.0 /spl mu/m)/spinel). A high value of k/sup 2/=23.5% with 50% diffraction efficiency has been obtained for the spinel(0.5 /spl mu/m)/KNbO/sub 3/(1.0 /spl mu/m)/spinel structure at 1 GHz SAW frequency and 633 nm optical wavelength at a very low input drive power of 15.4 mW.     

On a weaker notion of controllability of a language K withrespect to a language L

A necessary and sufficient condition for a prefix-closed language K⊆Σ* to be controllable with respect to another prefix-closed language L⊆Σ* is that K⊆ L. A weaker notion of controllability where it is not required that K⊆L is considered here. If L is the prefix-closed language generated by a plant automaton G, then essentially there exists a supervisor Θ that is complete with respect to G such that L(Θ|G)=K ∩ L if and only if K is weakly controllable with respect to L. For an arbitrary modeling formalism it is shown that the inclusion problem is reducible to the problem of deciding the weaker notion of controllability. Therefore, removing the requirement that K ⊆ L from the original definition of controllability does not help the situation from a decidability viewpoint. This observation is then used to identify modeling formalisms that are not viable for supervisory control of the untimed behaviors of discrete-event dynamic systems     

Effects of nitrogen trifluoride on the growth and properties of plasma-enhanced chemical-vapor-deposited diamond-like carbon films

The effects of nitrogen trifluoride (NF₃) on the growth and properties of plasma-enhanced chemical-vapor-deposited diamond-like carbon (DLC) films were investigated. The addition of NF₃ increases the deposition rate of DLC film due presumably to the removal of activated hydrogen species by the fluorine radical (F⁻). Diamond-like carbon films deposited in a methane/NF₃ mixture have a higher refractive index, a lower bulk resistivity, and a lower optical bandgap compared to films deposited in pure methane due to a lower hydrogen content in the films. Moreover, the bulk resistivity of methane/NF₃ DLC films remains constant for annealing temperatures below 400°C. Thus, DLC films deposited with NF₃ are more stable than DLC films deposited without NF₃.     

Strengthening of a bridge pier capbeam using bonded FRP composite plates

Application of fiber reinforced polymer (FRP) composite plates to strengthen the capbeam of Pier 3 of East Church Street Bridge in Chemung County, New York, is discussed in this paper. Addition of a concrete wearing surface and a median barrier to the bridge superstructure increased dead load, contributing to deficiencies in moment and shear capacities of the capbeam structure. As a result, the concrete capbeam suffered flexural and shear cracking, and was considered for strengthening using bonded FRP composite plates. Service load tests were performed before and after the plates were installed, to investigate effectiveness of the strengthening system. Installation of the plates and results from the performed load tests related to flexural behavior of the beam are discussed in the paper.     

Buffer model and management in distributed multimedia presentation systems

The delivery of continuous and synchronous multimedia data from a database (or file) server to multiple destinations over a network presents new challenges in the area of buffer management. Many factors that were not considered in conventional buffer management must be examined. In this paper, we investigate the principles of buffer model and management for multimedia data presentations in distributed systems. The primary goal is to minimize the response time of multimedia presentations while ensuring that all continuity and synchronization requirements are satisfied. A framework for buffer model and management is introduced. Minimum buffering requirements at both client and server sides to guarantee the continuity and synchrony of the presentation of multimedia data are examined. A prefetching and replacement strategy which satisfies these requirements is then offered. These principles and techniques provide users with the full range of information required to develop a distributed system for multimedia presentations.     

Joint evaluation of multiple speech patterns for speech recognition and training

We are addressing the novel problem of jointly evaluating multiple speech patterns for automatic speech recognition and training. We propose solutions based on both the non-parametric dynamic time warping (DTW) algorithm, and the parametric hidden Markov model (HMM). We show that a hybrid approach is quite effective for the application of noisy speech recognition. We extend the concept to HMM training wherein some patterns may be noisy or distorted. Utilizing the concept of “virtual pattern” developed for joint evaluation, we propose selective iterative training of HMMs. Evaluating these algorithms for burst/transient noisy speech and isolated word recognition, significant improvement in recognition accuracy is obtained using the new algorithms over those which do not utilize the joint evaluation strategy.