Determination of crystallographic orientation of dwell-fatigue fracture facets in Ti-6242 alloy

A technique to determine the crystallographic orientation of the fracture facets has been described. The spatial orientation of the facet plane is determined in a scanning electron microscope (SEM) using a quantitative tilt fractography technique. The crystallographic orientation of the grain, across which a particular fracture facet had been produced, is determined using the electron backscattered diffraction (EBSD) technique in an SEM. These two pieces of information were combined to obtain the crystallographic orientation of the fracture facet normal. This technique was used for the characterization of dwell-fatigue fracture facets at the crack-initiation site in Ti-6242 alloy. Our results indicate that these facets are not exactly aligned with the basal plane, but are inclined at ∼10° to it.     

Dynamic Forwarding over Tree-on-DAG for Scalable Data Aggregation in Sensor Networks

Computing and maintaining network structures for efficient data aggregation incurs high overhead for dynamic events where the set of nodes sensing an event changes with time. Moreover, structured approaches are sensitive to the waiting-time which is used by nodes to wait for packets from their children before forwarding the packet to the sink. Although structure-less approaches can address these issues, the performance does not scale well with the network size. We propose ToD, a semi-structured approach that uses Dynamic Forwarding on an implicitly constructed structure composed of multiple shortest path trees to support network scalability. The key principle behind ToD is that adjacent nodes in a graph will have low stretch in one of these trees in ToD, thus resulting in early aggregation of packets. Based on simulations on a $2000$ nodes network and real experiments on a $105$ nodes Mica2-based network, we conclude that efficient aggregation in large scale networks can be achieved by our semi-structured approach.     

Segmented Alignment: An Enhanced Model to Align Data Parallel Programs of HPF

In this paper, we propose a new automatic data alignment model called segmented alignment. The conventional data alignment model, such as that used in High-Performance Fortran (HPF), aligns arrays with the whole index domain. The principle of our proposed segmented alignment is to allow alignment relations within delimited index domains. We first provide motivating examples to illustrate how code fragments of HPF with EOSHIFT or CSHIFT operations, or produced by synthesis operations can benefit from our enhanced alignment scheme. Second, we show that this new model can be implemented in HPF-like languages by adding WHEN and IN constructs to them. In addition, we show that the new proposed schemes for WHEN and IN constructs can be emulated using standard HPF syntax. Finally, we address issues related to automatic data alignment for the new proposed model, and present an algorithm to automatically align programs using our segmented alignment scheme. Since the optimal algorithm to do this is NP-hard, a practical heuristic is also given. Our experiments were performed on a DEC Alpha Farm with HPF environments. Our experiments confirm our theory that our proposed alignment scheme can significantly enhance not only the performance of HPF code fragments with EOSHIFT or CSHIFT operations, but also that of codes produced by synthesis operations.     

Hot-electron transport in In0.53Ga0.47As

A set of physical constants for In_0.53Ga_0.47As as required for transport calculations is obtained by reviewing the literature. Velocities for fields up to 100 kV/cm, calculated by the Monte Carlo method using these constants, are presented for the temperatures of 95 and 300 K. The calculated values are found to be in good agreement with the available experimental results.     

Low-power scan design using first-level supply gating

Reduction in test power is important to improve battery lifetime in portable electronic devices employing periodic self-test, to increase reliability of testing, and to reduce test cost. In scan-based testing, a significant fraction of total test power is dissipated in the combinational block. In this paper, we present a novel circuit technique to virtually eliminate test power dissipation in combinational logic by masking signal transitions at the logic inputs during scan shifting. We implement the masking effect by inserting an extra supply gating transistor in the supply to ground path for the first-level gates at the outputs of the scan flip-flops. The supply gating transistor is turned off in the scan-in mode, essentially gating the supply. Adding an extra transistor in only one logic level renders significant advantages with respect to area, delay, and power overhead compared to existing methods, which use gating logic at the output of scan flip-flops. Moreover, the proposed gating technique allows a reduction in leakage power by input vector control during scan shifting. Simulation results on ISCAS89 benchmarks show an average improvement of 62% in area overhead, 101% in power overhead (in normal mode), and 94% in delay overhead, compared to the lowest cost existing method.     

Treatment of wastewater containing Pb and Fe using ion‐exchange techniques

Treatment of wastewater containing lead and iron was examined using two different ion‐exchange resins namely Duolite ES 467 (containing amino‐phosphonic functional groups) and a chelating ion‐exchange resin (containing hydroxamic acid functional groups). Initially different sorption parameters such as contact time, pH, concentrations of sorbent, sorbate and chloride ion were studied. The sorption kinetics was observed to be fast and equilibrium could be reached within 30 min. Lead sorption efficiency increased with increase in pH whereas the opposite trend was observed with iron. The presence of chloride ions greatly reduced the Pb sorption efficiency in the case of Duolite ES 467. Column studies were carried out to recover Pb and Fe individually using Duolite ES 467 resin. The maximum uptake of Pb at pH 2 and 3 was observed to be 11.63 and 33.96 g dm^?3 of resin respectively. Similarly, for Fe at pH 2 and 3 the uptake was observed to be 10.07 and 6.96 g dm^?3 of resin respectively. In the presence of chloride ions, column studies were carried out using Duolite ES 467 for iron and chelating ion‐exchange resin containing hydroxamic acid functional groups for lead sorption. Hydroxamic acid resin's loading capacity remains constant for at least up to 20 cycles. Copyright © 2005 Society of Chemical Industry     

Monomeric and dimeric phenolic acids released from cell walls of grasses by sequential treatment with sodium hydroxide

Cell walls of tall fescue Festuca arundinacea Schreb and coastal bermudagrass Cynodon dactylon L Pers were treated sequentially with increasing concentrations of sodium hydroxide (0·1 M to 10 M) to release monomeric and dimeric phenolic acids. (E)-p-Coumaric and (E)-ferulic acids were the major monomers released. Most of the saponifiable feruloyl groups (97% for tall fescue, 89% for coastal bermudagrass) were released with 0·1 M sodium hydroxide. Much lower proportions of saponifiable p-coumaroyl groups (67% for tall fescue, 46% for coastal bermudagrass) were released with this treatment. The major dimers from both grasses were 4,4′-dihydroxy-α-truxillic, 4,4′-dihydroxy-3-methoxy-α-truxillic, and 4,4′-dihydroxy-3,3′-dimethoxy-α-truxillic acids, and were mainly released with 0·1 M sodium hydroxide. Similar proportions of the monomers and dimers were released from the cell walls of each grass with the 0·1 M and 1 M sodium hydroxide sequential treatments. It is probable that most if not all of the monomers and dimers released by the sequential alkali treatments were originally ester linked to the cell walls. If it is assumed that the cell wall bound dimers are formed photochemically from p-coumaroyl and feruloyl groups during plant growth, it is calculated that, for the two grasses, between 12 and 17% of the monomer units were converted to dimers.     

Capacitances in double-barrier tunneling structures

Capacitances in a double-barrier tunneling structure are calculated for the specific sequential electron tunneling regime. Starting from Luryi's (1988) definition of quantum capacitance, the authors model the charge accumulation in the well during the tunneling process using the Fermi-Dirac distribution. Analytical formulas for the total capacitance and conductance are derived. A complete small-signal model is proposed that demonstrates the external capacitance and conductance of the structure and its frequency behavior. The authors show both theoretically and experimentally that the capacitance in a tunneling structure is both bias- and frequency-dependent     

Determination of system-matrices of linear continuous-time multivariable systems from discrete-time models

It is shown that the computed system matrix for a continuous-time multivariable system may have the imaginary parts of its eigenvalues shifted from their true values when the matrix is determined from a discrete-time model. The same type of eigenvalue shift also can occur if a kth root of a matrix is used in the system identification. A numerical example is given to show that either predicted eigenvalue shift can occur. A bound on the sampling interval is suggested to avoid eigenvalue shifts.<>