排序方式: 共有84条查询结果,搜索用时 17 毫秒
1.
简要介绍了Schneider公司的Modbus和Modbus Plus总线,并提出了基于Modbus和Modbus Plus的交流传动控制网络.重点讨论了此控制网络的系统配置和梯形图设计,这种控制网络控制方便,传输精度高. 相似文献
2.
对手工制图、二维CAD制图和三维CAD制图3种方式进行了比较,指出三维CAD软件有取代二维CAD软件的趋势。成功应用SolidWorks 2001Plus三维CAD软件进行锅炉设计,可极大提高企业的产品开发效率。 相似文献
3.
Aspen wood substrates with varying degrees of deacetylation, xylan, and lignin removal have been prepared and submitted to
enzymatic hydrolysis with a cellulase/hemicellulase preparation for an extended constant period of hydrolysis. Controlled
deacetylation has been achieved by treating wood with various alkali metal hydroxide solutions, at various alkali/wood ratios.
It has been found that samples with the same extent of deacetylation produce the same sugar yields upon enzymatic hydrolysis.
Increased degree of deacetylation increases the yield of sugars obtained from enzymatic hydrolysis, all other compositional
parameters held constant. The acetyl group removal is proportional to the stoichiometric relation between added base and wood
acetyl content, i.e., the same number of milliequivalents of base/weight of wood remove the same extent of acetyl groups,
regardless of the concentration of the base solution. No cation effects are found among Li, Na, and K alkali hydroxide solutions,
suggesting that swelling is not as important a parameter as is the removal of the acetyl groups from the xylan backbone in
determining the extent of hydrolyzability of the resulting sample. 相似文献
4.
时青 《福建师范大学学报(自然科学版)》2004,20(3):101-105
在高职教育中,受教育成本和资金的限制,实验室并不具备相关的设计环境.就EDA设计理念和工具在普通数字电路教学中的应用做简要探讨,以期得到融传统教学方式和现代化设计理念为一体的教学效果. 相似文献
5.
Nucleus Plus操作系统是Accelerated Technology公司推出的操作系统软件,它为程序开发者提供一个实时、抢占、多任务的操作系统环境。它采用了微内核的设计模式,为整个系统提供了良好的性能。主要介绍Nucleus Plus微内核的一种基本功能模块——定时器模块的工作原理,并通过对定时器作原理的深入分析,增加了定时器重新启动、修改定时长度的功能。完善了Nucleus Plus对定时器的控制能力。 相似文献
6.
生物质经快速热解制备的生物油是一种清洁的可再生能源产品.为此,利用气相色谱质谱联用仪分析了生物油的组分性质,采用填料式精馏塔对生物油进行实沸点(true boiling point,TBP)蒸馏实验,实验分别在常压环境(0.1,MPa)及减压环境(0.01,MPa)下进行,得到了生物油的3个宽馏分.结果表明:在常压环境下,汽油馏分的收率为19.2%,柴油馏分的收率为26.4%;在减压环境下,汽油馏分收率为30.5%,柴油馏分收率为23.3%.在实验的基础上,本文利用Aspen Plus软件建立了生物油实沸点蒸馏的模拟流程,并计算得到了生物油的恩氏蒸馏曲线. 相似文献
7.
In this paper, we will prove that the plus cupping degrees generate a definable ideal on c.e. degrees different from other
ones known so far, thus answering a question asked by Li and Yang (Proceedings of the 7th and the 8th Asian Logic Conferences.
World Scientific Press, Singapore, 2003). 相似文献
8.
Determination of halogenated flame retardants by liquid chromatography coupled to mass spectrometry 总被引:1,自引:0,他引:1
We present an overview of current analytical methods for selected halogenated flame retardants (HFRs), focusing on instrumental determination using liquid chromatography coupled to mass spectrometry. We based the strategy for literature search on recent articles published in peer-reviewed scientific journals or conference proceedings. We report on selected HFRs and some metabolites and transformation products, and on the analytical performances of different ionization modes, with emphasis on selectivity and sensitivity. Moreover, we compare these parameters with those obtained by gas chromatography. 相似文献
9.
The hydrocarbon plus fractions that comprise a significant portion of naturally occurring hydrocarbon fluids create major problems when determining the thermodynamic properties and the volumetric behavior of these fluids by equations of state. These problems arise due to the difficulty of properly characterizing the plus fractions (heavy ends). Proper characterization of the heavier components is important when cubic equations of state and/or solid formation thermodynamic models are used to describe complex phase behavior of reservoir fluids. The effect of heavy fractions characterization on thermodynamic modeling of wax precipitation has been investigated using different models including Won, Pan and proposed models. In order to characterize the plus fraction (heavier part) as a series of pseudocomponents, a probability model that expresses the mole fraction as a continuous function of the molecular weight has been used. The study has been conducted using several mixtures. Two different SCN (single carbon number), C7+ and C10+ were chosen. The Chosen SCN were distributed to multi-components of five, six, and/or ten using continuous function and Gaussian quadrature method. The results showed that the fractioning is required to be able to predict wax precipitation. Distribution of C10+ using a proper distribution function has shown improvement in predictions of WAT and the amount of wax deposited in comparison with the characterization of C7+ using semi-continuous approach. In predicting of WAT and the amount of wax build up the developed model showed superiority over the others. 相似文献
10.
Kaitang Hu Tianjin University of Science Technology Tianjin ChinaYonghao Ni Limerick Pulp Paper Centre UNBP.O. Box Fredericton NB CanadaXuejun Zou Paprican St. John''''s Blvd.Pointe Claire QC CanadaYajun Zhou Tembec Inc. P.O. Box Temiscaming QC Canada 《天津科技大学学报》2004,19(Z1)
INTRODUCTIONBleached CTMP (BCTMP) is popular in many commercial paper grades, such as packaging, tissue, uncoated wood-free fine papers. There is a strong economic incentive to substitute BCTMP for kraft pulp in producing wood-free light weight coated paper (LWC). Wood free LWC is used mostly for high-speed heatset web offset (HWSO) color printing. With a low basis weight and also low coat weight, the strength, surface and structural properties of the LWC wood-free paper are al… 相似文献