煤矿井下交流电量信号的采样及算法

分析了交流采样、直流采样方法的优缺点,针对交流电量的采样,采用了交流采样方式,通过比较交流采样中傅立叶算法和均方根算法的特点,确定了交流采样中采用傅立叶算法处理交流信号,提高了保护系统的总体性能。     

烹饪时间对鱼肉中脂肪酸的影响

目的 考察不同烹饪时间对鱼肉中脂肪酸营养价值的影响, 并对不同鱼类的适宜烹调时间进行评价。方法 采用清蒸的方式对秋刀鱼、石斑鱼、鲫鱼和罗非鱼进行烹调, 利用氯仿-甲醇提取法提取鱼肉脂肪酸, 通过气相色谱技术(gas chromatography, GC)对鱼肉中脂肪酸进行定性定量, 讨论烹饪时间对不同鱼肉中脂肪酸含量变化的影响。结果 随着烹饪时间的增加, 4种不同种类的鱼肉中不饱和脂肪酸的含量都呈现下降趋势, 当烹饪时间为0.5~1.0 h时, 不饱和脂肪酸二十碳五烯酸(eicosapentaenoic acid, EPA)、二十二碳六烯酸(docosahexaenoic acid, DHA)、油酸、亚油酸、亚麻酸含量下降速率最快并且产生有害脂肪酸(反式脂肪酸), ω-6/ω-3脂肪酸比值也呈现出上升趋势, 鱼肉脂肪酸营养价值降低。结论 在对鱼肉进行烹饪时, 应严格控制鱼肉烹饪时间在0.5 h左右, 才能有效的保证鱼肉中脂肪酸的营养价值。     

HW-01系列防蜡降粘剂在不加热集油中的应用

为解决大庆油田环状集油流程“三不”(油井采出液不掺水、不加热 ,油井不用热水洗井 )集油试验中集油管道压降上升过快、抽油机不能正常生产的困难 ,在油井油套环形空间连续点滴和批加HW 0 1系列油井及集油管道防蜡降粘剂 ,取得了油井防蜡和降低集油管道压降双重功效 ,既实现了试验集油环秋季、冬季和春季 2 2 1天“三不”集油 ,又节省了大量的油井清防蜡剂 ,取得了良好的节能降耗效果。本文对该试验作了简要的介绍 ,指出了试验过程中出现的一些问题并提出了改进意见。     

用转轮流动模拟器测定气液混输管道中原油析蜡温度

本文介绍了转轮流动模拟器在气液混输管道中原油析蜡温度测定中的应用,测定了甲烷与原油混相体系的压力对原油析蜡温度的影响。证实了甲烷与原油两相共存情况下,体系压力升高可使原油析蜡温度降低。     

鱼油中多氯联苯检测方法的研究

目的建立毛细管气相色谱法测定鱼油中多氯联苯的方法。方法用氢氟酸和浓硫酸的混合溶液消解样品,以正己烷提取、浓硫酸净化后,用毛细管气相色谱法测定。结果方法的回收率为92.6%~105.2%,相对标准偏差(RSD)为2.98%~4.71%,最低检出限为0.25~0.48μg/kg。结论该方法简便、快捷,其灵敏度、准确度和精密度均能满足鱼油中多氯联苯分析的要求。     

柴油降凝剂与柴油组成的感受性研究

通过红外光谱法确定降凝剂的主要成分为聚乙烯-醋酸乙烯酯。对来自黑龙江、大连、吉林的0号柴油(依次编号为1~3)进行降凝剂感受性实验。结果表明,聚乙烯-醋酸乙烯酯降凝剂对柴油的感受性较好,可使1~3号柴油的凝点分别降低31、9、26℃,冷滤点分别降低18、12、21℃。2号柴油总正构烷烃含量（17.74%）高于1号（14.29%）和3号（13.03%）柴油,其C10~C19含量占总含量的87.2%。2号柴油的正构烷烃含量较高,因此其降凝效果较1、3号差。采用了偏光显微镜、差示扫描量热法（DSC）以及X射线衍射法（XRD）研究了降凝剂对蜡晶形貌和热力学的影响。加入降凝剂后,蜡晶颗粒由不规则的细长棒状变成细小的类球状。DSC分析结果表明,加剂后1、2号柴油析蜡高峰值温度由-1.46、-2.38升至0.46、2.41℃,结晶峰斜率均变小,在相变过程的固-液相变能（ΔH）绝对值由3278、5.283降至3.459、1.737 J/g。降凝剂通过改变固-液相变能来改变柴油的低温流动性。XRD测试结果表明,降凝剂与柴油发生了共晶作用,蜡晶聚集方式改变,单一晶型生长速率降低。综合偏光显微镜与DSC以及XRD结果说明,降凝剂的降凝机理是成核理论与共晶理论的共同作用。     

一种局部化的线性流形自组织映射

提出一种局部化的线性流形自组织映射方法, 可自主学习高维向量空间中的一组有序的低维线性流形. 与现有的基于Kohonen的自适应子空间自组织映射网络(Adaptive-subspace self-organizing map, ASSOM)方法相比较, 本文方法有效地克服了流形表达中出现的数据混淆现象, 网络中各神经元渐近学习各自区域内样本数据的平均向量和主元子空间, 数据表达更加清晰可辨. 实验中, 新方法对数据簇的分类准确率明显优于参与对比的其他三种方法, 其对手写体数字识别的准确率在MNIST训练集和测试集上分别达到了98.26\%和97.46\%.     

Investigation of Characteristics of Al2O3/n-In x Ga1−x As (x = 0.53, 0.7, and 1) Metal–Oxide–Semiconductor Structures

The electrical properties of Al₂O₃/n-InGaAs metal–oxide–semiconductor capacitors (MOSCAPs) with In content of 0.53, 0.7, and 1 (InAs) have been investigated. Results show small capacitance–voltage (C–V) frequency dispersion in accumulation (1.70% to 1.85% per decade) for these MOSCAPs, mostly being assigned to border traps in Al₂O₃. With higher In content, shorter minority-carrier response time and smaller C–V hysteresis are observed. The reduction of C–V hysteresis might be related to the reduction of Ga-bearing oxides in Al₂O₃/InGaAs interfaces as indicated by x-ray photoelectron spectroscopy.     

Rough Fuzzy Inference Model and its Application in Multi-factor Medium and Long-term Hydrological Forecast

This paper targets efforts to integrate rough set theory and the fuzzy inference technique into the multi-element medium and long-term hydrological forecast. Rough set theory is used to predigest the data and deal with the redundant inconsistent initial information table. Accordingly, the factors are reduced with the attribute significance concept. The minimal solution which is as fuzzy inference forecast pattern rule set in the model is achieved according to the principle of maximal attribute significance and combination significance as well as rules frequency. The model is applied to forecast annual runoff of Dahuofang Reservoir in China. The results indicate that the forecast precision is improved with rough set and the model can effectively reflect the non-linear relations between the runoff and factors and provide an effective and adaptable method to solve forecast problems related to complex factors selection and minimal inference rule set generation.     

A Forecast Model of Hydrologic Single Element Medium and Long-Period Based on Rough Set Theory

On the basis of rough set theory, this paper presents the single element medium- and long-term classification forecast model that uses historical data of a hydrologic series as forecast factors. The minimal rule set, i.e., forecast pattern set, is achieved according to the principle of maximal attribute significance and rules frequency. Maximal support strength is put forward and applied to predict by using the model. The model is applied to forecast annual runoff of Dahuofang reservoir. The result indicates that the forecast model based on rough set can describe the relationship between forecast factors and forecast object efficiently and accurately. This model, which is composed of simple solution rules, can be easily understood and applied.