甲酸甲酯合成与转化的催化技术

本文评述了甲酸甲酯(MF)合成与转化的催化技术,展示了从MF出发发展C_1化学的可能途径,在MF的合成方面详细地分析了从甲醇出发的羰化法、脱氢法和氧化法催化技术,简介了我们的有关研究工作。     

BELL整体比例调节型电动执行机构的电路连接与调试方法

天津贝尔自动化仪表技术有限公司引进法国先进技术,生产的电动执行机构广泛用于自动控制系统。新一代“卓越引进系列”具有多种保护功能和多种控制方式,更适宜现代工控需求。在百种以上规格中,搞清楚最基本类型——标准整体比例调节型是其他类型的基础。文章结合厂家提供的资料,针对整体比例调节型电动执行机构的重要方面进行了深入的分析与总结：一是组成与原理框图;二是电路器件的作用与电路连接;三是调试的项目与具体方法。     

Coking kinetics of a Cr2O3/Al2O3 catalyst during 1-butene dehydrogenation: Effect of H2 partial pressure

The influence has been studied of the partial pressure of hydrogen (0–30 kPa) upon the coking rate of a Cr₂O₃/Al₂O₃ commercial catalyst during 1-butene dehydrogenation. Coke deposition has been analysed using a monolayer-multilayer reversible coke growth model (MMRC model). This model provides good fits to the experimental data, within the range of partial pressure of H₂ studied, and allows us to estimate the main kinetic parameters involved in the coking-deactivation process. The results obtained reveal a dual effect of hydrogen: competition against 1-butene for the active sites and the removal of coke precursors from the catalyst surface. Bom effects diminish the coking rate as the H₂ partial pressure is increased.     

Electrochemical performance of nanocrystalline Li3V2(PO4)3/carbon composite material synthesized by a novel sol–gel method

A novel sol–gel method based on V₂O₅·nH₂O hydro-gel was developed to synthesize nanocrystalline Li₃V₂(PO₄)₃/carbon composite material. In this route, V₂O₅·nH₂O hydro-gel, NH₄H₂PO₄, Li₂CO₃ and high-surface-area carbon were used as starting materials to prepare precursor, and the Li₃V₂(PO₄)₃/carbon was obtained by sintering precursor at 750 °C for 4 h in flowing argon. The sol–gel synthesis ensures homogeneity of the precursors and improved reactivity. The sample was characterized by XRD, SEM and TEM. X-ray diffraction results show Li₃V₂(PO₄)₃ sample is monoclinic structure with the space group of P2₁/n. The TEM image indicates that the Li₃V₂(PO₄)₃ particles modified by conductive carbon are about 70 nm in diameter. The Li₃V₂(PO₄)₃/carbon system showed that the discharge capacities in the first and 50th cycle are about 155.3 and 143.6 mAh/g, respectively, in the range of 3.0–4.8 V. The sol–gel method is fit for the preparation of Li₃V₂(PO₄)₃/carbon composite material which may offer some favorable properties for commercial application.     

普钙产品转化率的数值计算方法

对影响普钙产品转化率的各种因素进行了分析,利用MATLAB 软件包得到了转化率的计算公式,提出了确定未分解磷矿的比例和由倍半氧化物引起的有效磷退化幅度的方法,为生产系统的预测和调整提供了一种途径。     

Multi-label core vector machine with a zero label

Multi-label core vector machine (Rank-CVM) is an efficient and effective algorithm for multi-label classification. But there still exist two aspects to be improved: reducing training and testing computational costs further, and detecting relevant labels effectively. In this paper, we extend Rank-CVM via adding a zero label to construct its variant with a zero label, i.e., Rank-CVMz, which is formulated as the same quadratic programming form with a unit simplex constraint and non-negative ones as Rank-CVM, and then is solved by Frank–Wolfe method efficiently. Attractively, our Rank-CVMz has fewer variables to be solved than Rank-CVM, which speeds up training procedure dramatically. Further, the relevant labels are effectively detected by the zero label. Experimental results on 12 benchmark data sets demonstrate that our method achieves a competitive performance, compared with six existing multi-label algorithms according to six indicative instance-based measures. Moreover, on the average, our Rank-CVMz runs 83 times faster and has slightly fewer support vectors than its origin Rank-CVM.     

谈如何提高二次精制盐水质量

介绍了锦化化工(集团)有限责任公司提高二次精制盐水质量的成功经验,讨论了过滤系统中碳素烧结管间距、一次盐水的质量及其游离氯含量、人为操作失误和助体给料量等五大因素对二次精制盐水质量的影响,并采取了相应的措施,如调整合适的碳素烧结管间距、改走砂滤器、更换过滤器碳素管等。介绍了二次精制盐水精制系统树脂塔精制盐水的操作要素,诸如控制盐水流量最高为68m3/h、温度在(60±5)℃、pH值在9左右,控制树脂塔的压差、树脂填充量、树脂性能、仪表阀的检查情况等,从而生产出高质量的二次精制盐水,保证了离子膜电解槽的平稳、高效运行。     

探讨概率应用的几个典型问题

概率应用遍及自然科学和社会生活之中,科学的概率不仅应当服务于科学,更重要的是能够服务于概率应用。这里通过解决典型问题,剖析概率研究方法的特殊性,探讨概率应用的一般方法。     

浅谈C语言中循环结构的教学--回答好循环结构的“三个问题”

循环结构是C语言程序设计中的重难点,其掌握情况对于后续章节的学习效果尤为关键。本文以什么是循环、何时需要使用循环以及如何使用循环三个问题为主线,通过精心选择的教学案例和灵活有效的教学方法来进行解答,以激发学生兴趣,培养编程思想。     

探索行动导向教学法在网络架构课程教学改革中的应用

技工学校是以技术型人才培养为目的的学生能力养成和技能操作的教育基地,为确保人才培养质量,学校需要加强对市场形势的把握和教学改革的控制。行动导向教学法是目前广泛应用于技校和职校教学课堂的、有较好实际作用的教学方法,文章以行动导向教学法为重点,以配置交换机实现VLAN学习任务为案例,在教学方法和手段等几个方面讨论了行动导向教学法在网络架构课程教学改革中的研究与实践。