Single-event effects in resolver-to-digital converters

Single-event effects (SEEs) in two resolver-to-digital converters (RDCs) have been studied using heavy ions and pulsed laser light. The important role of the pulsed laser in establishing single-event upset (SEU) and single-event latchup (SEL) levels prior to accelerator testing is described, as is its role in evaluating the test software and hardware and in gaining a better understanding of the origins of the SEEs. Results from pulsed-laser testing are in quantitative agreement with those from heavy-ion testing: the RDC-19220 is sensitive to both SEUs and SELs whereas the AD2S80 is less sensitive to SEUs and immune to SEL     

Optimal block boundary pre/postfiltering for wavelet-based image and video compression.

This paper presents a pre/postfiltering framework to reduce the reconstruction errors near block boundaries in wavelet-based image and video compression. Two algorithms are developed to obtain the optimal filter, based on boundary filter bank and polyphase structure, respectively. A low-complexity structure is employed to approximate the optimal solution. Performances of the proposed method in the removal of JPEG 2000 tiling artifact and the jittering artifact of three-dimensional wavelet video coding are reported. Comparisons with other methods demonstrate the advantages of our pre/postfiltering framework.     

Increased discharge capacity of a Li-air activated carbon cathode produced by preventing carbon surface passivation

A significant discharge capacity increase (larger than 3 times) for the gas-diffusion-electrode (GDE) used in Li-air cells was demonstrated through modification of the carbon surface with long-chain hydrophobic molecules. The capacity loss of the Li-air activated carbon cathode was found to be caused by the formation of undesired surface passivation. The mechanism of such passivation was identified as the formation of dense Li oxide films directly on the surface of the carbon during the oxygen reduction reaction. Such dense layers of Li oxide are here identified as the root cause of the undesired passivation, which blocks electrochemical reactions, increases the impedance and drops the discharge voltage rapidly. This investigation reveals that the capacity for the gas-diffusion-electrode can be substantially increased, if the activated carbon is modified by attaching long-chain hydrophobic molecules onto the surface. The carbon surface modification significantly delays the formation of the dense Li oxide layers. Therefore, the discharge capacity for the GDE is substantially increased.     

Sensing and gait planning of quadruped walking and climbing robot for traversing in complex environment

In this paper, a general study on improving adaptability of quadruped walking and climbing robot in complex environment is presented. First, a sensing system composed of range and gyroscope sensors in a novel arrangement is developed. By combining the sensing signals and the internal state of the robot, the surface geometry of the environment is sufficiently reconstructed in real-time. Secondly, a planning algorithm for the robot to overcome the reconstructed environment is conducted. Based on the reshaped surface, the planning algorithm not only provides the exact body trajectory and foot positions but also the adaptability of the robot in a specific environment. A method to improve the adaptability of the walking and climbing robot is also introduced. Thanks to the adherent ability of the robot, the center of gravity of the robot is allowed to move outside the support polygon to increase the reach-ability of the next swing leg. Finally, the effectiveness of the proposed approach is verified by the performances of the experiments in complex environments using a quadruped walking and climbing robot named MRWALLSPECT IV.     

Impact of the lysine-188 and aspartic acid-189 inversion on activity of trypsin

The presence of heat stress protein genes (hsp) was tested by Southern hybridization analysis in total DNA extracts from species of the genus Streptococcus (47 strains), Lactobacillus (34 strains), Lactococcus (24 strains), and Leuconostoc (5 strains). The biotinylated hsp16.4 probe prepared from an ORF2 fragment of pER341 (2.8 kb) tested positively with restricted DNA extracts of seven Streptococcus thermophilus strains and a single strain of Lactococcus lactis subsp. cremoris. In all positive S. thermophilus strains, the hsp was located on plasmids ranging from ca. 2.8 kb to 11 kb in size, while hsp was present in a 7.5-kb plasmid in Lactococcus lactis subsp. cremoris. Southern blots with a rep probe showed that all hsp16.4+ plasmids in S. thermophilus strains also shared homology with the replication function (rep) of pER341, suggesting the common origin of these plasmids.     

Zero-Phase Filtering for Lightning Impulse Evaluation: A K-factor Filter for the Revision of IEC60060-1 and -2

The next revision of the international standard for high-voltage measurement techniques, IEC 60060-1, has been planned to include a new method for evaluating the parameters associated with lightning impulse voltages. This would be a significant improvement on the loosely defined existing method which is, in part, reliant on operator judgment and would ensure that a single approach is adopted worldwide to determine peak voltage, front, and tail times, realizing standardization in measured parameters across all laboratories. Central to the proposed method is the use of a K-factor to attenuate oscillations and overshoots that can occur with practical generation of impulse voltages for testing on high-voltage equipment. It is proposed that a digital filter that matches the K-factor gain characteristic be implemented and used for this purpose. To date, causal filter designs have been implemented and assessed. This paper is concerned with the potential application of a noncausal digital filter design to emulate the K-factor. The approach has several advantages; the resulting design is only second order, it can be designed without using optimization algorithms, it is a zero-phase design and it matches the K-factor almost perfectly. Parameter estimation using waveforms from the IEC 61083-2 test data generator and experimental impulse voltages has been undertaken and obtained results show that the zero-phase filter is the ideal digital representation of the proposed K-factor. The effect of evaluating parameters by the proposed method is compared to mean-curve fitting and the challenge of effective front-time evaluation is discussed.     

Optical add-drop multiplexers with low crosstalk

We propose and demonstrate three new optical add-drop multiplexer (OADM) architectures with simple and compact configuration and excellent crosstalk performance. The OADMs use a single multiport optical circulator and either one or two narrow-band fiber Bragg gratings, depending on the crosstalk requirement     

Studies on the Catalysis by Lithium Perchlorate of Reactions of Aromatic Amines with Diethyl Azodicarboxylate and Naphtalen-2-ol with 4-phenyl-1,2,4-triazoline-3,5-dione

The ene-like reaction of naphtalen-1-ylamine and naphtalen-2-ylamine, and pyridin-2-ylamine with diethyl azodicarboxylate (DEAD) as well as that of naphthalen-2-ol with 4-phenyl-1,2,4-trizoline-3,5-dione is catalyzed by lithium perchlorate. Also conversion of ester function of (DEAD) to amide function in reaction with 2-aminopyridine and further rearrangement of ethyl N-pyridyn-2-ylcarbamoylazoformate into ethyl pyridin-2-ylcarbamate are catalyzed by LiClO₄.