CaO——Al_2O_3——SiO_2系统中复合晶核剂(CaF_2+Cr_2O_3)的作用研究

本文采用DTA、STEM、ESR、XRD、IR等测试方法,研究了复合晶核剂(CaF_2+Cr_2O_3)对CaO——Al_2O_3——SiO_2系统玻璃的分相析晶行为和显微结构形貌的影响。结果表明,当CaF_2含量不大于5％时或Cr_2O_3含量小于3％时,二者单独引入基玻璃只能产生表面析晶;Cr_2O_3和CaF_2组成复合晶核剂共同引入玻璃时却能获得整体析晶,析晶的显微结构为放射状球晶,主晶相为β—硅灰石,通过控制该组成玻璃的析晶热处理制度。作者研制出了新型建筑饰面和艺术品材料——晶花玻璃[C·P·G]。     

可切削生物活性微晶玻璃在模拟细胞外液中的界面行为

实验通过模拟细胞外液(PECF)浸泡、扫描电镜/能谱微区分析、薄膜XRD、红外反射光谱分析及原子吸收光谱分析等方法,研究了以氟金云母和氮磷灰石为主晶相的微晶玻璃在生理环境中表面生物活性反应过程和机理,认为微晶玻璃中残余玻璃相的Ca~(2+)、PO_4~(-3)溶出及溶液中Ca~(2+)、PO_4~(3-)及OH~-相对于羟基磷灰石的过饱和状态对于材料表面磷灰石层的形成具有重要意义。表面磷灰石层是由最初的无定形含水CaO—P_2O_5薄层晶化转变而成。     

On singular nonlinearH ∞ control: A state-space approach

A simple state-space approach for the four-block singular nonlinearH control problem is proposed in this paper. This approach combines a (J, J)-lossless and a class of conjugate (J, J)-expansive systems to yield a family of nonlinearH output feedback controllers. The singular nonlinearH control problem is thus transformed into a simple lossless network problem that is easy to deal with in a network-theory context.This work was supported by the National Science Council, Republic of China, under contract NSC 87-2218-E009-026.     

GLLS for optimally sampled continuous dynamic system modeling: theory and algorithm

The original generalized linear least squares (GLLS) algorithm was developed for non-uniformly sampled biomedical system parameter estimation using finely sampled instantaneous measurements (D. Feng, S.C. Huang, Z. Wang, D. Ho, An unbiased parametric imaging algorithm for non-uniformly sampled biomedical system parameter estimation, IEEE Trans. Med. Imag. 15 (1996) 512-518). This algorithm is particularly useful for image-wide generation of parametric images with positron emission tomography (PET), as it is computationally efficient and statistically reliable (D. Feng, D. Ho, Chen, K., L.C. Wu, J.K. Wang, R.S. Liu, S.H. Yeh, An evaluation of the algorithms for determining local cerebral metabolic rates of glucose using positron emission tomography dynamic data, IEEE Trans. Med. Imag. 14 (1995) 697-710). However, when dynamic PET image data are sampled according to the optimal image sampling schedule (OISS) to reduce memory and storage space (X. Li, D. Feng, K. Chen, Optimal image sampling schedule: A new effective way to reduce dynamic image storage space and functional image processing time, IEEE Trans. Med. Imag. 15 (1996) 710-718), only a few temporal image frames are recorded (e.g. only four images are recorded for the four parameter fluoro-deoxy-glucose (FDG) model). These image frames are recorded in terms of accumulated radio-activity counts and as a result, the direct application of GLLS is not reliable as instantaneous measurement samples can no longer be approximated by averaging of accumulated measurements over the sampling intervals. In this paper, we extend GLLS to OISS-GLLS which deals with the fewer accumulated measurement samples obtained from OISS dynamic systems. The theory and algorithm of this new technique are formulated and studied extensively. To investigate statistical reliability and computational efficiency of OISS-GLLS, a simulation study using dynamic PET data was performed. OISS-GLLS using 4-measurement samples was compared to the non-linear least squares (NLS) method using 22-measurement samples, GLLS using 22-measurement samples and OISS-NLS using 4-measurement samples. Results demonstrated that OISS-GLLS was able to achieve parameter estimates of equivalent accuracy and reliability in comparison to NLS or GLLS using finely sampled measurements (22-measurement samples), or OISS-NLS using optimally sampled measurements (4-measurement samples). Further more, as fewer measurement samples are used in OISS-GLLS, this algorithm is computationally faster than NLS or GLLS. Therefore, OISS-GLLS is well-suited for image-wide parameter estimation when PET image data are recorded according to the optimal image sampling schedule.     

电力企业选购CAD系统原则的探讨

针对许多企业在CAD系统选购中存在片面的、错误的观念和做法,分析了导致CAN系统选购工作失败的原因,提出了“立足实用,兼顾先进,不盲目追求‘新、全’、高档次和高水平”的软、硬件购买原则,强调了软件选购要考虑软件公司和销售商的背景、软件的性能和功能及软件的易学易用等几个方面的问题．还详细论述了为什么要选国产名牌的微型机作为主机和要选主流的CPU芯片的问题．本文还就盗版软件的禁用和工程图纸扫描录入系统以及如何建立CAD网络系统提出了建议．     

Synthesis and characterization of photocrosslinkable poly(organophosphazene)-bearing cinnamyloxide side groups

Two different poly(organophosphazene)s-bearing single-substituents (two cinnamyloxide side groups per repeating unit) and phenoxide-co-substituents (one phenoxide and one cinnamyloxide group per repeating unit) were prepared to study their photochemical reaction behavior. Structural formulas confirmed by the NMRs (¹H, ³¹P) and IR were ? [NP(OCH₂CH = CH ? C₆H₅)₂]_n ? ( I ) and ? [NP(OCH₂CH = CH ? C₆H₅)_0.8 (O ? C₆H₅)_1.2]_n ? ( II ). Molecular characterization yielded $ \overline {M_w {\rm s}} $ of the order of 10³ kg/mol for both the polymers. The onset temperature of decomposition found by TGA was about 250°C. DSC measurements gave T_gs as 1°C for I and 3°C for II . Their photolytic crosslinking behaviors were monitored by UV spectroscopy. The single-substituents polymer I showed a faster rate of photo reaction than the polymer II . The potential use for practical photosensitive application is considered to be greater for the polymer I .     

PIC16C711在粮食温度水分快速测定中的应用

介绍了一种以ＰＩＣ１６Ｃ７１１微控制器为数据处理核心的粮食温度,水分快速 的构成,叙述了数据处理系统的工作机理,硬件构成和软件流程。     

面向中文移动通讯产品的点阵汉字压缩新技术及其压缩字形数据结构设计

本文介绍了一种新型点阵汉字压缩技术──“构件嵌套组合”技术的研究,该技术建立在统计学和汉字框架结构的基础上,可实现对汉字高效压缩,能够很好地满足中文移动通讯产品的需要。文中讨论了这种新型汉字压缩技术的主要设计思想及其压缩字形数据结构设计等。     

The Forgotten “Old-Darwinian” Synthesis: The Evolutionary Theory of Ludwig H. Plate (1862–1937)

The German zoologist and geneticist Ludwig Plate was a pupil and successor of the “German Darwin” Ernst Haeckel as the director of the Institute of Zoology at Jena University. Plate campaigned for a revival of the original Darwinism. His research program, which he labelled “old-Darwinism”, proclaimed the synthesis of selectionism with “moderate Lamarckism” and orthogenesis.This article reconstructs and analyses Plate’s “old-Darwinian” synthesis and sheds light on Plate’s controversial biography, especially his conflict with Haeckel. Our research was supported by the Deutsche Forschungsgemeinschaft (HO 2143/5–2).     

High impedance fault detection utilizing incremental variance ofnormalized even order harmonic power

A novel method for the detection of high-impedance faults is proposed which uses the incremental variance of a normalized even order ratio measure. Staged fault tests were extensively carried out in Korean electric power systems. From the analysis of the staged fault test data, it was found that there exists an intermittent arcing phenomenon in most high-impedance faults and that the waveforms of this arcing fault current have an asymmetrical shape in each cycle. Based on these facts, three criteria, (even-order power, even-order ratio, and even-order incremental variance) for fault detection are presented, all of which are based on the changes of normalized even-order harmonic power in fault currents. These criteria are compared through the analysis of staged fault data and normal switching event data. It is shown that the even-order incremental variance criterion is superior to the other two criteria and that, with this criterion, high-impedance faults can be distinguished from normal switching events, including special loads such as electric furnaces and subways. Microprocessor-based protective relays, which can detect high-impedance faults by using the proposed methods, have been constructed, installed in Korea Electric Power Corporation substations, and tested during the last two years. Details of these field tests are given