同步顶升法在化工装置改造中的应用

大庆石化公司炼油厂二重催MIP改造空冷器平台整体提升施工难度较大,经过分析、计算、方案对比,提出采用千斤顶同步顶升方法替代传统的吊装工艺,顺利的完成了260 t重的空冷器平台整体提升任务,不仅节约施工成本,同时还探索出一条化工装置有限空间施工的新途径。     

现代大客车技术分析

通过对国内外大客车三大总成的最新技术进行分析，探讨我国大客技术的发展方向。     

新型永磁式开关磁阻电动机电磁场的二维有限元分析

采用二维有了元模型对新型永磁式开关磁阻电动机的电磁场了分析。     

Numerical electromagnetic analysis of impulse voltage measuringsystems

The unit step response (USR) of lightning impulse voltage measuring systems is numerically calculated with the help of the Numerical Electromagnetic Code (NEC-2), which calculates the three-dimensional electromagnetic field around conducting wires. The accuracy of this analysis is proved satisfactory through comparison of the results of measurement with calculation. The advantage of this method is that the influence of the geometry of the circuit can automatically be calculated without evaluating stray capacitance in the system. Therefore, this method of analysis can be applied to the development of an impulse voltage divider, or in analyzing the influence of elements of a USR measuring circuit. The influence of the shield ring attached to a resistance divider, and of the vertical metal sheet in the IEC-recommended USR measuring circuit on the USR waveform is analyzed as an example     

Influences of Bentonite on conductivity of composite solid alkaline polymer electrolyte PVA-Bentonite-KOH-H2O

The influence of the dopant Bentonite, on the ionic conductivity of the PVA-KOH-H₂O alkaline solid polymer electrolyte (ASPE) is studied. The results show that the addition of Bentonite has both positive and negative effects on the ionic conductivity of ASPE. At lower KOH and H₂O contents, the addition of Bentonite can break the continuous ion conducting phase of the ASPE, and therefore decrease the ASPE conductivity. However, the addition of Bentonite can also increase the KOH content in PVA matrix. This greatly increases the conductivity of the ASPE especially at higher water content. A highest ionic conductivity of 0.11 S cm⁻¹ is reached at room temperature. A maximum ionic conductivity value is observed at relative lower water content for different amount of Bentonite-doped ASPE. The temperature dependence of the ionic conductivity is of the Arrhenius type. The ion transfer activation energy Ea, in the order of 4-6 kJ mol⁻¹, heavily depends on the Bentonite content. XRD and SEM tests show that PVA in the Bentonite-doped ASPE is of amorphous structure, and there are lots of interspaces in the composite ASPE inner structure. The composite electrolyte has good electrochemical stability window and good charged-discharge property in secondary Zn-Ni cells at low charge-discharge rate.     

超声辅助醇沉法制备淀粉纳米颗粒同步包埋叶黄素

为制备叶黄素淀粉纳米颗粒(SNPs-叶黄素)，以木薯淀粉为原料，叶黄素醇溶液为非溶剂相，通过超声辅助醇沉法制备淀粉纳米颗粒，同步实现对叶黄素的包埋负载。合理平衡叶黄素包埋量及包埋率两个目标参数，在质量分数为3%淀粉乳、叶黄素溶液质量浓度1 mg/mL、淀粉乳与叶黄素醇溶液体积比3∶10条件下，对叶黄素的包埋量达(57.62±0.36)mg/g，包埋率(40.33±0.56)%。场地发射扫描电镜显示同步包埋叶黄素未对淀粉纳米颗粒形貌产生显著影响，均为表面光滑的球状或椭圆状颗粒。激光纳米粒度仪显示SNPs-叶黄素尺寸分布在200～600 nm范围。傅里叶红外光谱显示SNPs-叶黄素在2 856 cm-1处出现叶黄素的C-H特征峰，在1 645 cm-1处H-O-H的振动发生蓝移。X射线衍射显示，与SNPs的大包峰相比，SNPs-叶黄素在7.8，13.1和20.9出现V型淀粉特征衍射峰。贮藏稳定性试验表明，在30 d内，室温(25 ℃)和升温条件下(50 ℃)，SNPs-叶黄素中叶黄素的保留率高于叶黄素原料药。     

贮氢负极的电化学交流阻抗特性研究

通过试验测得金属氢化物电极的电化学交流阻抗谱（ＥＩＳ），经过分析得到该电极的等效电路图。为了分析电极在不同状态下的阻抗及不同种类电极的阻抗，ＥＩＳ被用于其分析：（１）不同带电态的电极；（２）不同集流体电极；（３）不同化成态的电极。试验结果表明：（１）随放电深度的增加，电荷传递阻抗Ｒ７有先减小后增大的趋势，温伯格阻抗对应电导逐渐减小；对此进行了理论分析；（２）泡沫镍在电极中起到的集流作用不一定明显优于冲孔镍带，但可能由于镍的电催化作用，能减小电极反应的电子转移步骤阻抗；（３）以充放电方式的电化学化成主要是减小电荷转移阻抗，而对温伯格阻抗无明显影响。     

An edge preserved image compression technique

An image compression technique that can preserve edges of objects is proposed here. This technique is developed by looking at small local regions of the image and classifying these regions as uniform, point, line or edge patterns from statistical likelihood ratio tests. The compression ratio depends on the size of the local region considered and the quality of the image will degrade as the size of the local region increases. Experimental results show good quality preservation when the sizes of the local region are 3 × 3, 4 × 4, 5 × 5 with the corresponding compression ratios less than or equal to 7/24, 1/5, 13/100 respectively. A comparison with discrete cosine transform is given here and shows that the new technique produces better quality in most cases.