用卡尔曼滤波技术提高机械加工精度

本文首先阐述了卡尔曼滤波的基本原理,导出了卡尔曼滤波的递推表达式,然后以高精度丝杠车床为例建立了加工中误差信号的数学模型,并用PB-700型个人计算机仿真。仿真果表明,这种方法可将原机床加工的螺距精度提高到0.5μm级。仿真还揭示了应用这种方法精化机床提高加工精度的原因,为结构设计、传感器选择、建立数学模型、合理选择采样间距等提供了方向性指示。     

Histological observation of some primitive euconodonts of Late Cambrian from Liaoning

The histology of some euconodonts of Late Cambrian from Benxi and Fuxian County, Liaoning Province is studied by the oil-immersion technique. The histological characteristics of six primitive species of euconodonts - Proconodontus muelleri， Proconodontus tenuiserratus， Granatodontus ani， Rotundoconus tricarinatus， Teridontus nakamurai and Cordylodus proavus are described in detail. Tubular dentine and atubular (parallel- and wavy-lamellar) dentine are found in the basal bodies of the primitive euconodonts Proconodontus tenuiserratus and Proconodontus muelleri, respectively. The tubular dentine and spherulitic dentine are also recognized from the basal bodies of Granatodontus ani and Rotundoconus tricarinatus. Since the histological characteristics of the studied six species of euconodonts belonging to Proconodontus lineage and Teridontus lineage Sensu Miller (Univ Kansas Paleontol Contr, 1980, 99: 1?39) seems to be almost the same, euconodonts are proposed as possibly monophyletic herein.     

聚酰胺酰亚胺(PAI)的合成及改性环氧树脂/DDS体系研究(Ⅲ)TDE-85/PAI/DDS体系碳纤维复合材料的力学性能及断貌

考查了在TDE-85/DDS体系中加入不同端基,不同分子量的PAI后对其碳纤维复合材料性能的影响。结果发现,PAI的分子量在19 000～40 000范围内对复合材料的影响不大,而PAI有无活性端基和用量的影响却较大,并发现,加入20％未封端的PAI到TDE-85/DDS体系中所制得的复合材料的综合性能最好,其断裂韧性G_(IL)可提高63％左右,并且不影响其热性能,此外,还用SEM对复合材料断貌进行了分析。     

沈阳市南运河水质分析及微生物区系分布调查

本文对南运河水质和微生物分布进行了分析和测定。结果表明南运河水质已受到严重的污染、细菌数量达到１．７×１０￣６～８．０×１０￣８个／ｍｌ，ＣＯＤ＿（ｃｒ）、ＢＯＤ＿５、挥发酚、ＮＨ＿３－Ｎ、氰化物的浓度均超出地面水质标准十几倍乃至几十倍，尤其是挥发酚和氰化物的污染更为严重。     

Structure of the Sec23/24-Sar1 pre-budding complex of the COPII vesicle coat

COPII-coated vesicles form on the endoplasmic reticulum by the stepwise recruitment of three cytosolic components: Sar1-GTP to initiate coat formation, Sec23/24 heterodimer to select SNARE and cargo molecules, and Sec13/31 to induce coat polymerization and membrane deformation. Crystallographic analysis of the Saccharomyces cerevisiae Sec23/24-Sar1 complex reveals a bow-tie-shaped structure, 15 nm long, with a membrane-proximal surface that is concave and positively charged to conform to the size and acidic-phospholipid composition of the COPII vesicle. Sec23 and Sar1 form a continuous surface stabilized by a non-hydrolysable GTP analogue, and Sar1 has rearranged from the GDP conformation to expose amino-terminal residues that will probably embed in the bilayer. The GTPase-activating protein (GAP) activity of Sec23 involves an arginine side chain inserted into the Sar1 active site. These observations establish the structural basis for GTP-dependent recruitment of a vesicular coat complex, and for uncoating through coat-controlled GTP hydrolysis.     

细菌降解氰的研究

通过驯化富集培养，从煤气厂曝气池活性污泥中分离出一株能降解氰的菌株，经鉴定为芽孢杆菌属。该菌对氰有较高忍受能力，降解氰的最适条件为：充分曝气供氧；温度为３５℃，ＰＨ＝９．０；在条件下，培养液中氰的浓度为１０．８９ｍｇ／Ｌ时，摇床振荡培养３５小时，氰的降争率可达６１．９％。     

BAN逻辑与串空间的比较

研究了2种安全协议的分析方法,即BAN逻辑和串空间.利用这2种方法分别分析了Needham-Schroeder公钥协议,指出了这2种方法各自的优点和缺点.在对这2种方法进行了比较后,指出了这2种方法有2种结合方式.1种是利用串空间给出BAN逻辑的语义,另外1种结合方式是串行,即对于需要分析的协议,先利用BAN逻辑进行分析,然后再利用串空间进行分析,使分析出的结果更加可靠.     

关于矩阵范数的几个问题

矩阵算子范数和矩阵酉不变范数是两大类矩阵范数。它们既有区别又有联系。本文首先讨论了一个矩阵范数‖·‖既是算子范数又是酉不变范数的条件。另外，文[4]中在讨论正规矩阵谱变分问题时，用到单调范数和单调酉不变范数的概念。本文证明了，只有F－范数是单调的酉不变范数。另外，在所有的p－范数中，只有1－范数和∞－范数是单调范数。     

Optimal procedure for fitting the magnetic susceptibility vs J couplings

To provide efficiency in calculating the energy-levels of paramagnetic spin clusters with high nuclear -ity, a fitting program of irreducible tensor operator is developed for the calculation of / couplings. An optimal data-access process is given, which greatly enhances the computational aspects of such modeling. Upon the program's application, the coupling constants of the moderate-sized clusters are fitted automatically by the least-squares calculations in PCs.     

华南地区湖南省芙蓉统(上寒武统)的古蠕虫骨片:个体生长对表皮骨片形态的影响

报道最近发现的华南地区湖南省芙蓉统(上寒武统)三维保存的古蠕虫骨片碎片。描述两个新的形态属和两个新的形态种: Hunanoscolex campus 新属新种和Ornatoscolex hunanensis新属新种。大部分标本属于幼体阶段。Hunanoscolex campus体节宽度的巨大差异显示其处于生长发育阶段, 因此可以对个体生长对表皮骨片形态的影响进行研究。虫体生长主要依靠增加单个体节中骨片的数量。位于同一排中的大骨板排列变得疏松。新增加的小骨板和微骨板大小和纹饰基本不变, 但大骨板的纹饰可能存在变化。这些观察结果有助于更好地理解古蠕虫骨片的种内差异, 从而可能提高形态种属分类的准确性。