Dual band-notched ultra-wideband microstrip antenna using asymmetrical spurlines

A simple and novel ultra-wideband microstrip-fed antenna with dual band-notched characteristic is presented. By etching a pair of asymmetrical spurlines on the feedline, two notched bands of 600 MHz (3.95? 4.55 GHz) and 650 MHz (5.35?6.0 GHz) are achieved. Measured results show that this antenna operates from 2.5 to 12.0 GHz for voltage standing wave ratio less than 2, except two frequency notched bands of 3.95?4.55 GHz and 5.35?6.0 GHz. Moreover, this antenna has good omnidirectional radiation patterns in the H-plane.     

Effect of current stressing on the reliability of 63Sn37Pb solder joints

The effect of current stressing on the reliability of 63Sn37Pb solder joints with Cu pads was investigated at temperatures of −5 °C and 125 °C up to 600 h. The samples were stressed with 3 A current (6.0 × 10² A/cm² in the solder joint with diameter of 800 μm and 1.7 × 10⁴ A/cm² in the Cu trace with cross section area of 35 × 500 μm). The temperatures of the samples and interfacial reaction within the solder joints were examined. The microstructural change of the solder joints aged at 125 °C without current flow was also evaluated for comparison. It was confirmed that the current flow could cause the temperature of solder joints to rise rapidly and remarkably due to accumulation of massive Joule heat generated by the Cu trace. The solder joints stressed at 125 °C with 3 A current had an extensive growth of Cu₆Sn₅ and Cu₃Sn intermetallic compounds (IMC) at both top and bottom solder-to-pad interfaces. It was a direct result of accelerated aging rather than an electromigration or thermomigration effect in this experiment. The kinetic is believed to be bulk diffusion controlled solid-state reaction, irrespective of the electron flow direction. When stressed at −5 °C with 3 A current, no significant change in microstructure and composition of the solder joints had occurred due to a very low diffusivity of the atoms as most Joule heat was eliminated at low temperature. The IMC evolution of the solder joints aged at 125 °C exhibited a subparabolic growth behavior, which is presumed to be a combined mechanism of grain boundary diffusion and bulk diffusion. This is mainly ascribed to the retardant effect against the diffusion course by the sufficiently thick IMC layer that was initially formed during the reflow soldering.     

WARD: a transmission control protocol-friendly stateless active queue management scheme

In this article, the problem of providing a fair bandwidth allocation to the flows sharing a congested link in a router is investigated. Queue management, bandwidth share and congestion control are very important to both the robustness and fairness of the Internet. The buffer at the outgoing link is a simple FIFO, shared by packets belonging to the flows. A new transmission control protocol (TCP)-friendly router-based active queue management scheme, termed WARD, is proposed to approximate the fair queueing policy. WARD is a simple packet-dropping algorithm with a random mechanism which discriminates against flows that submit more packets per second than is allowed as their fair share. By doing this, it not only protects TCP connections from user datagram protocol flows, but also solves the problem of competing bandwidth among different TCP versions, such as TCP Vegas and TCP Reno. In addition, WARD works quite well for TCP flow isolation even with different round trip times. In other words, WARD improves the unfair bandwidth allocation properties. Furthermore, as it is stateless and easy to implement, WARD controls unresponsive or misbehaving flows with only a minimum overhead.     

Biodegradation of phenol at low temperature using two-phase partitioning bioreactors.

Two-phase partitioning bioreactors offer many advantages for the removal of toxic pollutants. In particular, such systems can be loaded with very large quantities of pollutants without risks of microbial inhibition, they are self-regulated and they prevent the risks of hazardous pollutant volatilisation during aerobic treatment. However, their potential has never been tested at low temperatures. Phenol biodegradation by a cold adapted Pseudomonas strain was therefore tested at 14 or 4 degrees C using 2-undecanone, diethyl sebacate or 2-decanone as organic phases in a two-phase partitioning bioreactor. The three solvents were biocompatible at 14 degrees C but evidence was found that diethyl sebacate was biodegraded by the bacteria and this solvent was not tested further. Although only 2-decanone was suitable at 4 degrees C, phenol biodegradation was more efficient in 2-undecanone at 14 degrees C, reaching a maximum volumetric rate (based on the volume of aqueous phase) of approximately 1.94 g/L.day after 47 h of cultivation. In 2-decanone at 14 degrees C, evidence was found that phenol degradation was limited by the release of biosurfactants, which increased the solubility and toxicity of the solvent in the aqueous phase inhibiting microbial activity. This study therefore shows that pollutant removal at low temperature is feasible but that the production of biosurfactants can have a negative impact on the process and must be taken into consideration when selecting the organic solvent. Future work should therefore focus on the selection of solvents suitable for use at temperatures below 14 degrees C.     

Health promotion for women with physical disabilities: A pilot study.

Objective: To pilot test a health promotion intervention for women with physical disabilities. Design: Pre- and postintervention questionnaires. Participants: Two groups of women with physical disabilities (n=15). Intervention: Seven-session weekly workshop intervention grounded primarily in social-cognitive theory. Setting: Disability and rehabilitation settings. Main Outcome Measures: Indicators of health status. Results: Statistically significant positive changes between pre- and postintervention scores on measures of self-efficacy for dietary behaviors, medical decision making, social interaction, physical functioning, impact of physical limitation on role activities, and vitality. Conclusion: Women with disabilities who participate in this health promotion intervention may exhibit improvements on indicators of health status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CO毒化AB5型合金分形特征研究

研究了三种贮氢合金 L a Ni5、L a Ni4 .7Al0 .3、Ml Ni4 .5Al0 .5被 10 0× 10 - 6 CO毒化后的分形特征 ,求出这三种合金在含 10 0× 10 - 6 CO的氢中循环 ,分维分别为 0 .2 5 4 7、0 .170 9、0 .0 72 5。可以较好的解释合金被毒化的宏观现象。