单电容有源带阻滤波器

这种新型的有源滤波器,只用一个电容器、一个运算放大器和两个电阻器。该电路能实现带阻和低通滤波特性,其极点品质因数可以独立调整而不影响其它参数。文中给出了实验结果,证明了理论分析的正确性,分析了在中心频率处阻带衰减为有限值的原因,认为这是运放附加相移的影响。     

A role—Based Fuzzy Assignment Model

It's very important to dynamically assign the tasks to corresponding actors in workflow management system, especially in complex applications. This improves the flexibility of workflow systems. In this paper, a role-based workflow model with fuzzy optimized intelligent assignment is proposed and applied in the investment management system. A groupware-based software model is also proposed.     

colitis.In the drug sensitivity tests of Proteus,t

c bacteria causing summer diarrhea,and is also one of the pathogenic factors leading to ulcerative colitis.proteus;;diarrhea;;sensitivity0检验医学与临床Laboratory Medicine and Clinic48-49R516;R446.5E060     

Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean

Submarine hydrothermal venting along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such vents has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of vent-endemic organisms. Previous studies have predicted that the incidence of hydrothermal venting would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates <2 cm x yr(-1)-which make up 25 per cent of the global ridge length), and that such vent systems would be hosted in ultramafic in addition to volcanic rocks. Here we present evidence for active hydrothermal venting on the Gakkel ridge, which is the slowest spreading (0.6-1.3 cm x yr(-1)) and least explored mid-ocean ridge. On the basis of water column profiles of light scattering, temperature and manganese concentration along 1,100 km of the rift valley, we identify hydrothermal plumes dispersing from at least nine to twelve discrete vent sites. Our discovery of such abundant venting, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control hydrothermal circulation on ultraslow-spreading ridges.     

Stability Analysis of Ranking Alternatives Based on Subjective and Objective Weight

1　 IntroductionWeights of criteria are used to assess the relative importance of the different criteria inmulticriteria analysis,which can influence ranking result more or less depending on themulticriteria decision-making( MCDM) method used.Determining the weights ofcriteria isusually a difficult task due to the decision-maker( DM) is not always clear about how toweightfor each criterion and is noteasy to understand thatthe change of weightinfluencesthe ranking results from qualitative mea…     

An improved digital watermarking scheme combining with PKC 

Digital watermarking is the enabling technology to prove ownership on such copyrighted product as software, documents, music, and video, monitor the usage of them, and even trace them back to the user with embedding of unique buyer identification(ID) as a part of watermark into them. This thread of detection will deter users from releasing unauthorized copies. A problem arises when the seller is dishonesty, he has a chance to use the digital watermarking with the buyer ID maliciously and make the buyer receive falseaccusation. In this paper, an improved digital watermarking scheme is introduced to prevent falseaccusation to an honest buyer, which is combined with the advantage of PKC(public key certificate) so that it fits the online transaction and helps to realize secure ecommerce. In addition, the extended application of this scheme is discussed.      

高频连续时间的高阶0TA-C滤波器的直接实现

本文提出了一种具有跨导运算放大器和电容的高阶OTA-C 滤波器的实现方法,此类滤波器的灵敏度低,且截止频率高,调整方便,适于全集成,文中用实验证明了它的可行性。     

A Convergent Algorithm for Continuously Optimal Location Problem

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Magmatic and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge,Arctic Ocean

A high-resolution mapping and sampling study of the Gakkel ridge was accomplished during an international ice-breaker expedition to the high Arctic and North Pole in summer 2001. For this slowest-spreading endmember of the global mid-ocean-ridge system, predictions were that magmatism should progressively diminish as the spreading rate decreases along the ridge, and that hydrothermal activity should be rare. Instead, it was found that magmatic variations are irregular, and that hydrothermal activity is abundant. A 300-kilometre-long central amagmatic zone, where mantle peridotites are emplaced directly in the ridge axis, lies between abundant, continuous volcanism in the west, and large, widely spaced volcanic centres in the east. These observations demonstrate that the extent of mantle melting is not a simple function of spreading rate: mantle temperatures at depth or mantle chemistry (or both) must vary significantly along-axis. Highly punctuated volcanism in the absence of ridge offsets suggests that first-order ridge segmentation is controlled by mantle processes of melting and melt segregation. The strong focusing of magmatic activity coupled with faulting may account for the unexpectedly high levels of hydrothermal activity observed.