A procedure for automatically estimating model parameters in optical motion capture

Model-based optical motion capture systems require knowledge of the position of the markers relative to the underlying skeleton, the lengths of the skeleton's limbs, and which limb each marker is attached to. These model parameters are typically assumed and entered into the system manually, although techniques exist for calculating some of them, such as the position of the markers relative to the skeleton's joints. We present a fully automatic procedure for determining these model parameters. It tracks the 2D positions of the markers on the cameras' image planes and determines which markers lie on each limb before calculating the position of the underlying skeleton. The only assumption is that the skeleton consists of rigid limbs connected with ball joints. The proposed system is demonstrated on a number of real data examples and is shown to calculate good estimates of the model parameters in each. © 2004 Elsevier B.V. All rights reserved.

重金属在菲律宾蛤仔体内的富集及其毒理效应

本文研究了重金属在菲律宾蛤仔体内的富集及其毒理效应，包括镉（Cd）对菲律宾蛤仔的毒性、Cd在蛤仔体内不同组织的富集规律、锌（Zn），铅（Pb）单一胁迫及联合胁迫下，蛤仔消化腺和鳃Zn、Pb的富集及其金属硫蛋白的含量变化。 利用水生生物毒性试验方法，分6个浓度梯度进行Cd对蛤仔的急性毒性实验，得出48h、96h半数致死量，分别为4.790mg/L、0.878mg/L，计算出Cd对菲律宾蛤仔的安全质量浓度为0.00878mg/L。根据急性毒性实验结果设定实验用海水中Cd的浓度分别为10μg/L、50μg/L、100μg/L、200μg/L及一个对照组共5组，研究了Cd在蛤仔不同组织内的积累规律。结果表明菲律宾蛤仔鳃和消化腺对Cd的富集能力较强，远高于外套膜和肌肉。实验同时显示，随着时间的延长，Cd的浓度增加，Cd富集量也增加。

National report of the frame survey 2006 in the Ugandan part of Lake Victoria

Fisheries Frame surveys have been carried out on Lake Victoria biannually since 2000 to determine· the number of fishers, fish landing sites, facilities at the landing sites. Information on the composition fishing crafts, their mode of propulsion, fishing gears and the fish species they target is also collected. This information is used to guide development and management of the lake's fisheries. The results of the four surveys carried out since 2000 show that the number of landing sites has decreased by 24% from 597 in 2000 to 481 in 2006, mainly as result of reorganisation of landing sites into Beach Management Units (BMUs). The fish landing sites continue to have inadequate facilities to service the fisheries industry e.g. in the 2006 survey only 11.2% of landing sites had fish shades; <0.6% had cold rooms; 3.5% had electricity; and only 35.5% had toilet facilities. Similarly, only 11.4% of landing sites had portable water; 2.5% had jetties, 3.7% had 'fish stores; and 36% were accessible by all weather roads. There is need to improve facilities servicing fisheries at landing sites, with major emphasis on sanitary facilities, especially toilets and portable water. The BMUs should be sensitised to prioritise the construction and utilisation of public toilet facilities at their respective landing sites. The ultimate aim should be to have public toilets at all fish landing sites. The trend of the various indicators of fishing effort has continued upwards: The total number of fishers increased by 43.5% from 37,721 in 2004 to 54,148 in 2006 and the number of fishing crafts increased (43.9%) from 16,775 in 2004 to 24,148 in 2006 over the same period. The total number of gillnets increased by 28.6% from 458,597 in 2004 to 589,777 in 2006 and the number of long line hooks increased by 136% from 968,848 to 2,285,609. The number of fishing crafts using outboard engines also increased from 3,173 in 2004 to 5,047 in 2006 suggesting that more fishers were going far in search of fish. There is still a large number of illegal gears especially beach seines, which increased by 58.8% from 954 in 2004 to 1420 in 2006. Efforts to remove these very destructive gears should be stepped up. There was also larger increase in number of illegal gillnets <5 inch mesh size. These increased by 63% from 56,246 in 2004 to 91,740 in 2006 compared with 23.8% increase of gillnets ~5 inch mesh size. There were also large increases in the numbers of gillnets of 5 and 5% inch mesh size, which increased by 48% and 130% from 2004 to 2006 implying a trend towards use of smaller gillnet mesh sizes. The number of traps which are used in shallow vegetated areas, flood plains and river mouths to target tilapiines and riverine species decreased drastically from 5,361 traps in 2004 to only 499 traps in 2006, a decrease of 974%, a phenomenon attributed to the receding water levels which have left the shallow vegetated areas dry. A total of 17,475 fishing crafts, 72% of all fishing crafts, in the Ugandan part of the lake are still using paddles and the. number of parachute crafts is also still very high, (Le. 5,064) comprising a high proportion (21 %) of the total number of fishing. There is need to promote the use of large fishing crafts with sails or a combination of sail and outboard motor. The Mukene fishery in the Ugandan waters of Lake Victoria has remained underdeveloped with only 9% of all fishing crafts operating in this fishery. Also less than 2% of fishing crafts with sails or motor operate in this fishery which implies that it is limited to near shore waters. Effort should be made to develop this fishery as it appears to have high potential, especially in deep offshore waters which are hardly fished.

大功率四象限直流脉冲开关电源

本实用新型涉及一种新型控制原理的大功率四象限直流脉冲开关电源，可以以直流、脉冲两种方式运行。以电流为横坐标轴，电压为纵坐标轴，电源可以在四个象限运行。该开关电源包括低压变压器、高压变压器、低压整流桥、高压整流桥、斩波电路及负载；其中斩波电路由ＩＧＢＴ模块组成。本实用新型基于脉宽调制工作方式，继承了开关电源输出电压纹波小，反应速度快调节灵敏度高的优点，同时有其自身的优点：主回路结构清晰、控制方式简单、输出功率大、电流输出稳定度高、工作可靠性高、电磁兼容性好。