由低品位Mamatwan锰矿生产高品位锰烧结矿的研究

由低品位Ｍａｍａｔｗａｎ锰矿生产高品位锰烧结矿的研究Ｐ．Ｃ．ＰｉｅｎａａｒＷ．Ｆ．Ｐ．Ｓｍｉｔｈ（Ｓａｍａｎｃｏｒ公司Ｍａｍａｔｗａｎ锰矿）南非拥有１３６亿吨Ｍｎ＞２０％的锰矿，是一个锰和铁合金的主要生产国。由于高品位锰市场不断竞争的增长需要，以及产...     

让评测文章不再是天书（五）——看懂评测之音箱篇

音箱是构成PC多媒体系统的关键配件．因此关于音箱的评测也经常出现在各种媒体上。由于音箱评测不像CPU、主板、显卡等配件那样比较容易量化．因此音箱评测中的主观因素相对其他配件要多了很多，这也就给广大读者带来了麻烦——要看懂音箱评测报告还真不容易！     

1001个最佳免费软件——从Internet上下载

使用Net的最大好处并不在于访问漂亮的图片、恐怖的声音或成千兆字节的信息,而是因为那里有无数的免费软件可以随时下载使用。当然,有些东西是不值得花很长时间去下载的。因此,PC Computing的编辑们遍历了Internet,选出了1001个最佳的软件。我们从最小的个人页面直至Ziff-Davis Interactive的Shareware LibrarV这样的巨型网点都搜索了一遍,找出了令人惊叹的应用程序、激动人心的游戏和大量的热门软件。每一个软件都已装入了我们的Web节点:www.pccomputing.com,准备供您下载,对您来说再没有比这更简便的了。     

Behavioral Changes in Workers of the Leaf-Cutting Ant Atta sexdens rubropilosa Induced by Chemical Components of Eucalyptus maculata Leaves

The response of Atta sexdens rubropilosa Forel workers to essential oils, epicuticular wax and hexane, dichloromethane, ethyl acetate, and methanol extracts of Eucalyptus maculata was evaluated. Hexane extracts of E. maculata interfered with the recognition mechanism among workers. The main active compounds identified from this plant were the sesquiterpenes elemol and beta-eudesmol. These compounds may be responsible for the resistance of this species to ant attack.     

A generalized series approach to MR spectroscopic imaging

The problem of precise spatial localization of spectral information in magnetic resonance (MR) spectroscopic imaging is addressed. A novel method, called GSLIM (generalized spectral location by imaging), is proposed to make possible the marriage of high-resolution proton imaging with spectroscopic imaging and localization. This method improves on the conventional Fourier series inversion method used in chemical shift imaging (CSI) and the compartmental modeling method used in SLIM by using a generalized series framework for optimal representation of the spectral function. In this way, a priori information extracted from proton imaging can be used, as in SLIM, and the robustness and data consistency of CSI are also retained. Simulation results show that GSLIM can significantly reduce spectral leakage in CSI and inhomogeneity errors in SLIM. It can also reveal compartmental inhomogeneities, and can easily be extended to handle other a priori constraints when necessary. This approach, with some further development, may achieve an optimal combination of sensitivity, quantitative accuracy, speed, and flexibility for in vivo spectroscopy.     

Development of the heat treatment system for the 40 T hybrid magnet superconducting outsert

The heat treatment of Nb(3)Sn coil with the glass fabric insulation is one of the key and critical processes for the outsert solenoids of the 40 T hybrid magnet, which could be wound with cable-in-conduit conductors using the insulation-wind-and-react technique. The manufacturing of the large vertical type vacuum/Ar atmosphere-protection heat treatment system has been completed and recently installed in the High Magnetic Filed Laboratory, Chinese Academy of Sciences. The heat treatment system composed mainly the furnace, the purging gas supply system, the control system, the gas impurities monitoring system, and so on. At present, the regulation and testing of the heat treatment system has been successfully finished, and all of technical parameters meet or exceed specifications.     

Photon counting with passively quenched germanium avalanche

We demonstrate photon counting in germanium avalanche photodiodes biased beyond breakdown and quenched with a simple series resistance circuit. The devices show moderate (> 7%) quantum efficiency with limited afterpulsing and dark counts and subnanosecond jitter.