|
| ||
|
|
||
Branch Lines (branch + line)
Selected AbstractsDual-band hybrid coupler with extended bandwidthMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2010King Yin Cheung Abstract A dual-band branch-line quadrature coupler with extended bandwidth using simple three-section branch line is presented. This proposed design exhibits larger bandwidth than existing dual-band designs reported in previous literature. A dual-band branch-line coupler was designed and measured to give 34.5 and 16.4% bandwidth in the lower band and upper band, respectively, for an amplitude imbalance less than 1 dB. The achieved bandwidth is wide enough to cover wireless local area network and wideband code division multiple access applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2095,2098, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25405 [source] Fishing gears involved in entanglements of minke whales (Balaenoptera acutorostrata) in the East Sea of KoreaMARINE MAMMAL SCIENCE, Issue 2 2010Kyung-Jun Song Abstract Entanglement of marine mammals in fishing gear is a global issue. It is considered a significant threat to minke whales (Balaenoptera acutorostrata) in the East Sea of Korea. A total of 214 entanglements of minke whales in this area between 2004 and 2007 were used to investigate types and parts of fishing gears involved in entanglements. The majority of entanglements were mainly caused by three types of fishing gears: set nets, pots, and gill nets (n= 207, 96.7%). Other entanglements were associated with bottom trawls, purse seines, and trawls. A total of 65 entanglements were attributed to the main and branch lines of fishing gears. The most common body part of minke whales which attached to fishing gears was the mouth (n= 63, 30.4%). Most entanglements took place within 10 nmi from land (n= 179, 86.5%), and between 10 and 220 m of water depth. The mean length of entangled minke whales in set nets was significantly smaller than that of whales in pots and gill nets samples (P < 0.001). Also, the mean body length of minke whales that entangled in the coastal area and shallow waters was significantly shorter than that of whales in the offshore area and deep waters (P < 0.001). This information can be used as fundamental data to conserve and manage this population of minke whales in the East Sea of Korea, and also to modify fishing gear to reduce entanglements. Future studies should focus on investigating the impact of these entanglements on the population and the effectiveness of mitigation measures to reduce entanglements of minke whales in this area. [source] Investigation into microstrip dual-mode bandpass filters (BPFS) with in-line feed-line configurationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2006JiaLin Li Abstract Based on the geometry relationship of the conventional dual-mode ring resonators, this study concisely describes the operation principle of a kind of dual-mode resonator filters with in-line feed-lines. The investigated filter topology is fed by two pairs of orthogonal branch lines and can realize in-line configuration for the input and output (I/O) ports, which is useful in many practical applications. Meanwhile, the influences of feed-lines on transmission-zeros (TZs) are, for the first time, investigated to guide the design of this kind of filters. Several demonstrators are designed and examined, and good results are obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2008,2013, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21845 [source] Experimental determinations of factors affecting the sink rates of baited hooks to minimize seabird mortality in pelagic longline fisheriesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2010Graham Robertson Abstract 1.An experiment was conducted in Australia's pelagic longline fishery to establish a scientific basis for the introduction of line weighting to reduce seabird mortality. The experiment examined the effects of different bait species (blue mackerel, yellow-tail mackerel and squid), bait life status (dead or alive), weight of leaded swivels (60,g, 100,g and 160,g) and leader length (distance between leaded swivel and hooks: 2,m, 3,m and 4,m) on the sink rates of baited hooks from 0,6,m deep. 2.On average, live bait sank much more slowly than dead bait. The sink rates of individual live bait were highly variable: many were <2,m underwater 18,s after deployment, including some on the heaviest swivels, and some were <10,m deep after 120,s. 3.Within the dead bait group, all three swivel weights on 3,m and 4,m leaders sank at similar rates. Initial sink rates (e.g. 0,2,m) were 2,3 times slower than final rates (e.g. 4,6,m) for all combinations of swivel weight and leader length. The fastest initial and final sink rates were associated with heavy swivels placed close to hooks. 4.The results show that (a) compared with dead bait, live bait greatly increases the exposure of baited hooks to seabirds; (b) initial sink rates of dead bait are increased by placing leaded swivels close to hooks and final rates by increasing the weight of the swivels; (c) adding weight to long leaders makes little difference to sink rates; and (d) the small (incremental) changes to swivel weights and leader lengths typically preferred by industry will be difficult to detect at sea and unlikely to substantially reduce seabird mortality. 5.We suggest that experiments designed to reduce seabird mortality from that associated with 60,g swivels and ,3.5,m leaders (the preferred option by industry) should aim to expedite the initial sink rates as well as rates to deeper depths. This objective could be achieved by including branch lines with ,120,g swivels ,2,m in comparative assessments of the effectiveness of line weighting regimes in reducing seabird mortality. Copyright © 2010 John Wiley & Sons, Ltd. [source] Effect of line shooter and mainline tension on the sink rates of pelagic longlines and implications for seabird interactionsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2010Graham Robertson Abstract 1. The likelihood that seabirds will be hooked and drowned in longline fisheries increases when baited hooks sink slowly. Fishermen target different fishing depths by setting the mainline through a line shooter, which controls the tension (or slackness) in the line. An experiment was conducted in Australia's pelagic longline fishery to test the hypothesis of no difference in sink rates of baited hooks attached to mainline set under varying degrees of tension. 2. Mainline was set in three configurations typically used in the fishery: (a) surface set tight with no slackness astern; (b) surface set loose with 2,s of slack astern; and (c) deep set loose with 7,s of slack astern. 3. Tension on the mainline had a powerful effect on sink rates. Baited hooks on branch lines attached to tight mainlines reached 2,m depth nearly twice as fast as those on the two loose mainline tensions, averaging 5.8,s (0.35,m,s,1) compared with 9.9,s (0.20,m,s,1) and 11.0,s (0.18,m,s,1) for surface set loose and deep set loose tensions, respectively. 4. The likely reason for the difference is propeller turbulence. Tight mainline entered the water aft of the area affected by turbulence whereas the two loose mainlines and the clip ends of branch lines were set directly into it about 1,m astern of the vessel. The turbulence presumably slowed the sink rates of baited hooks at the other end of the branch lines. 5. The results suggest that mainline deployed with a line shooter (as in deep setting) into propeller turbulence at the vessel stern slows the sink rates of baited hooks, potentially increasing their availability to seabirds. Unless mainline can be set to avoid propeller turbulence the use of line shooters for deep setting should not be promoted as an effective deterrent to seabirds. Copyright © 2010 John Wiley & Sons, Ltd. [source] | ||||||||||