同步接口电路时序检测实用方法

根据我国航天测控通信网中设备现状,针对同步数据传输中存在的因接口设计不规范、不匹配而引发的异常现象,从实际需要出发,通过国内外多个相关标准的综合分析研究,确定了与标准相适应的时序关系判断依据,结合以往工程经验,提出了简便实用的检测方法和时序关系异常判定原则,制定了切实可行的解决措施。应用方法解决了多个数据传输异常问题,并在后续设备联试和接口排查中得到推广应用和检验,取得良好效果。     

Using mixture experimental design to study the effect of multifunctional acrylate monomers on UV cured epoxy acrylate resins

An epoxy acrylate resin was synthesized and the resin was used along with different multifunctional acrylate monomers, i.e. trimethylol propane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanedioldiacrylate (HDDA). The effect of the chemical structure of the monomers on some of the physical–mechanical properties of the resins and their cured films, such as viscosity, T_g, hardness and scratch resistance was studied. To minimize the number of experiments, mixture method was used as an appropriate tool for experimental design.     

Polyimides derived from 1,4‐bis [3‐oxy‐(N‐aminophthalimide)] benzene

A novel diamine, 1,4‐bis [3‐oxy‐(N‐aminophthalimide)] benzene (BOAPIB), was synthesized from 1,4‐bis [3‐oxy‐(N‐phenylphthalimide)] benzene and hydrazine. Its structure was determined via IR, ¹H NMR, and elemental analysis. A series of five‐member ring, hydrazine‐based polyimides were prepared from this diamine and various aromatic dianhydrides via one‐step polycondensation in p‐chlorophenol. The inherent viscosities of these polyimides were in the range of 0.17–0.61 dL/g. These polymers were soluble in polar aprotic solvents and phenols at room temperature. Thermogravimetric analysis (TGA) showed that the 5% weight‐loss temperatures of the polyimides were near 450°C in air and 500°C in nitrogen. Dynamic mechanical thermal analysis (DMTA) indicated that the glass‐transition temperatures (T_gs) of these polymers were in the range of 265–360°C. The wide‐angle X‐ray diffraction showed that all the polyimides were amorphous. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

松香中海松酸型树脂酸在酸作用下的组成变化规律

详细研究了在溶液状态下酸催化作用引起松香中海松酸型树脂酸组成变化的特征及规律,以甲苯、醋酸等作为溶剂,醋酸、盐酸、硫酸等作为催化剂,反应温度为保持良好回流,反应时间1～8h。研究结果表明,松香中的海松酸型树脂酸在醋酸作用下比较稳定,其组成没有发生明显的变化。在盐酸、硫酸作用下,松香中原有的海松酸、异海松酸、山达海松酸明显减少,初始质量分数越高、酸作用时间越长,减少越明显,与此同时产生了原料中没有的8,15-异海松酸、8,15-海松酸和7,15-海松酸,且随酸作用时间延长而增多。在质量分数为51.4%的硫酸催化作用下于甲苯中回流8h后,湿地松松香中的海松酸型树脂酸质量分数变化为:异海松酸由13.77%降至10.53%,山达海松酸由1.78%升至1.98%,8,15-异海松酸则从0升至5.05%;马尾松松香中的海松酸型树脂酸质量分数变化为:海松酸由7.45%降至3.02%,7,15-海松酸由0升至0.67%,8,15-海松酸则从0升至3.99%。海松酸型树脂酸主要发生以环内双键位置变化为主的异构反应,很少发生分解反应,而环外乙烯基则没有参与反应,松香中各海松酸型树脂酸总质量分数基本不变。对海松酸型树脂酸各成分的立体结构分析及异构体之间的相关性分析结果表明,8,15-异海松酸应来源于异海松酸和山达海松酸的异构化,而8,15-海松酸和7,15-海松酸应来源于海松酸的异构化反应。     

分子电性距离矢量预测金线莲挥发油成分结构表征及色谱保留值

采用分子电性距离矢量(molecular electro-negativity distance vector,MEDV)对金线莲挥发油中分离的72种化合物进行了结构表征,并采用SPSS统计处理软件对变量进行了逐步回归(SMR)分析,建立了4变量的定量结构-色谱保留(quantitative structure retention relationship,QSRR)相关模型,同时采用内部及外部双重验证的办法对所建模型稳定性进行了分析和验证,建模计算值、留一法(leave-one-out,LOO)交互检验预测值和外部样本预测值的复相关系数R、RLOO、Qext分别为0.959,0.947,0.913。结果表明,MEDV能较好地表征非同类化合物的分子结构信息,所建模型具有良好的稳定性和预测能力,将其用于中药化学成分分离、分析、结构表征及其药用价值的有效开发,具有重要的理论指导意义。     

Genetic evaluation of dairy cattle using a simple heritable genetic ground

The evaluation of an animal is based on production records, adjusted for environmental effects, which gives a reliable estimation of its breeding value. Highly reliable daughter yield deviations are used as inputs for genetic marker evaluation. Genetic variability is explained by particular loci and background polygenes, both of which are described by the genomic breeding value selection index. Automated genotyping enables the determination of many single‐nucleotide polymorphisms (SNPs) and can increase the reliability of evaluation of young animals (from 0.30 if only the pedigree value is used to 0.60 when the genomic breeding value is applied). However, the introduction of SNPs requires a mixed model with a large number of regressors, in turn requiring new algorithms for the best linear unbiased prediction and BayesB. Here, we discuss a method that uses a genomic relationship matrix to estimate the genomic breeding value of animals directly, without regressors. A one‐step procedure evaluates both genotyped and ungenotyped animals at the same time, and produces one common ranking of all animals in a whole population. An augmented pedigree–genomic relationship matrix and the removal of prerequisites produce more accurate evaluations of all connected animals. Copyright © 2010 Society of Chemical Industry     

Towards High‐Performance Bioinspired Composites

Biological composites have evolved elaborate hierarchical structures to achieve outstanding mechanical properties using weak but readily available building blocks. Combining the underlying design principles of such biological materials with the rich chemistry accessible in synthetic systems may enable the creation of artificial composites with unprecedented properties and functionalities. This bioinspired approach requires identification, understanding, and quantification of natural design principles and their replication in synthetic materials, taking into account the intrinsic properties of the stronger artificial building blocks and the boundary conditions of engineering applications. In this progress report, the scientific and technological questions that have to be addressed to achieve this goal are highlighted, and examples of recent research efforts to tackle them are presented. These include the local characterization of the heterogeneous architecture of biological materials, the investigation of structure–function relationships to help unveil natural design principles, and the development of synthetic processing routes that can potentially be used to implement some of these principles in synthetic materials. The importance of replicating the design principles of biological materials rather than their structure per se is highlighted, and possible directions for further progress in this fascinating, interdisciplinary field are discussed.     

Studies on FRP-concrete interface with hardening and softening bond-slip law

This latest experimental study proposes a theory that the bond-slip law for a FRP-concrete interface contains linear hardening and exponential softening. On the basis of this law, the paper studies the mechanic behavior and debonding process of a FRP-concrete interface. Firstly, through nonlinear fracture mechanics, the analytical solutions of the interface shear stress, the axial normal stress of FRP and the load–displacement relationship at the loaded end with the single shear test model of FRP-concrete are acquired. The shear stress propagation as well as the debonding process of the whole interface for different bond lengths could be predicted. Secondly, a simplified interface bond-slip law is used by changing the exponential softening law into a linear softening law. In addition, the analytical solutions for the simplified interface bond-slip law could also be obtained. Finally, based on the analytical solutions of the two bond-slip laws, the influences of the FRP bond length and stiffness on load–displacement curve and the ultimate load, as well as stiffness on effective bond length were discussed, with the similarities and differences between the two bond-slip laws also being studied.     

Grain boundary transformation character in Fe-N austenite

The morphology and crystallography of the isothermal transformation of Fe-N austenite at 225 °C were characterized by transmission electron microscopy and scanning electronic microscope. Fe-N austenite was produced by through-nitriding thin pure iron sheets at 640 °C. Lath-shaped and periodically distributed (γ-austenite + γ′-Fe₄N + α-Fe) microstructures formed at the prior austenite grain boundaries, this kind of microstructure was shown to be bainite in nature and kept a Greninge-Troiano orientation relationship between the γ-austenite (γ´-Fe₄N) and α-ferrite. The formation mechanism of the grain boundary microstructure was shown to be the preferential precipitation of the proeutectoid γ′-Fe₄N at the grain boundary, followed by the transformation of the N-depleted austenite into α-ferrite and γ′-Fe₄N, thus forming a periodic γ-γ′-α-γ′-γ-γ′-α-γ′-γ-γ′ arrangement.     

工程机械出口行业客户关系管理数据仓库建模研究

以工程机械行业的客户关系管理系统建设为背景,围绕客户价值分析主题构建数据仓库维度模型．对客户关系管理数据仓库维度建模过程中的需求分析、高级维度模型设计、详细维度模型开发、维度模型评审和确认4个阶段进行了相应的规定描述,形成可供ETL、数据挖掘、联机在线分析等使用的数据仓库维度模型构建方案．