基于多目标混料设计的重介质旋流器混料成分配比

为了准确掌握重介质旋流器各混料成分之间的配比关系,明确不同配比对旋流器产出质量和产量的影响,实现分选效果的最优化.分析了现有旋流器优化和混料配比研究的不足,探讨了采用混料设计方法解决上述问题的可行性和局限性。通过设计混料试验,运行试验得到试验结果,建立混料成分与各响应变量的数学模型,分析模型的有效性,以各响应变量的同时最佳为综合约束条件进行响应优化,通过求解苛求函数复合合意度最高时的各参数值,确定各混料成分的最优配比,并通过T假设检验验证试验结果用于生产的有效性。结合某选煤厂旋流器生产运行情况,明确旋流器中块煤、悬浮液和煤泥各混料的水平要求,采用极端顶点法设计混料试验并运行试验,建立三因子与精煤灰分和产率两个响应变量之间的回归模型,分析两响应变量同时最佳条件下最优的混料配比,得到三混料成分配比依次为15.5%、59.8%、24.7%,依据上述配比进行试生产,并采用T检验验证试验结果是有效的,从而为选煤厂高效生产和精确控制提供有效的支撑,也为后期实现自动化控制提供了可能。     

扰流防舞器与气动力阻尼片的防舞效果

利用计算流体动力学方法,分别计算了安装有扰流防舞器、悬挂式阻尼片和固接式阻尼片的覆冰输电导线的气动力系数,计算结果表明:安装有扰流防舞器的导线,其不同截面的气动力可以互相抵消,扰流防舞器能够有效抑制导线的舞动;安装有悬挂式阻尼片的导线,其邓哈托系数恒大于0,其尼戈尔系数大幅度增大,悬挂式阻尼片也是有效的防舞装置;安装有固接式阻尼片的导线,其邓哈托系数和尼戈尔系数未发生改变,固接式阻尼片不是有效的防舞措施。     

Improve on/off ratio of organic heterojunction transistors by adopting single-sandwich configuration

Organic heterojunction transistors (OHJTs) based on 5,5′″-bis(naphtha-2-yl)-2,2′:5″,2′″-quaterthiophene (NaT₄)/copper-hexadecafluoro-phthalocyanine (F₁₆CuPc) heterojunction were fabricated in single-sandwich and sandwich configurations, respectively. All the devices operated in depletion-accumulation (normally-on) mode. High field-effect mobility of 0.35 cm²/Vs was obtained for all devices, which was higher than that, 0.20 cm²/Vs of the devices with NaT₄ as active layer. The on/off ratio of 1 × 10⁵ was obtained for OHJTs with single-sandwich configuration, which is three orders of magnitude higher than that of OHJTs with sandwich configuration. Compared with OHJTs with sandwich configuration, the higher on/off ratio was mainly determined by the lower off state current in OHJTs with single-sandwich configuration. In OHJTs with single-sandwich configuration, the well-type shield effect of the source and drain electrodes caused a very narrow empty region in F₁₆CuPc film, which is responsible for the lower off state current.     

Development of High Deformability Pipeline Steel

Based on strain-based design, high deformability X70 high strength pipeline steel with dual-phase microstructure has been developed, which can be laid in the seismic, the cold or the deepwater region. The results illustrated that the developed X70 steel has the stress-strain curve like round house and it shows good anti-transformation characteristic, high uniform deformation(≥10%), enhanced n-value(≥0.10), and the low yield-tensile ratio Y/T(≤0.85). The dual-phase microstructure of ferrite and bainite conta...     

油气减震支柱磨合试验台的机械原理设计

以油气减震支柱磨合试验的任务要求为输入,介绍了用减速机驱动平面四杆机构同时实现对两件产品进行磨合试验的设备的机械设计原理,该原理对其它相似产品试验台的机械设计有一定的借鉴和参考价值。     

Two‐dimensional guidelines for measurement system indices

In this paper, we review two common measurement system indices and a common process capability index. With some simple plots, it will be shown that the traditional guidelines for these measurement system indices can often misdirect improvement efforts. By taking advantage of the relationship between the measurement system indices and the process capability index, two‐dimensional guidelines that can be used as an alternative to the traditional guidelines are developed. These two‐dimensional guidelines are intended to help address adequacy of the measurement system and better direct improvement efforts to where there will be the most benefit. Copyright © 2010 John Wiley & Sons, Ltd.     

A/D变换器性能的分析与测量

讨论了A／D变换器的性能参数;深入分析了A／D变换器的噪声组成及其影响因素;介绍了信噪比、谐波失真度、有效位数的测量与实现。     

DFIG风电机组协同SVG抑制电网低频振荡方法

随着风电渗透率的日益增加,电力系统阻尼不足时易发生低频振荡,双馈风电机组（DFIG）可解耦控制有无功和无功输出,有利于增强系统阻尼。提出一种DFIG协同静止无功发生器（SVG）并网的方法,采用附加阻尼的控制策略,接入控制系统的功率控制节点,改变参考装置的有功和无功参考电流,实现装置动态输出功率,抵消功率增量,对系统中产生的功率振荡进行抑制。搭建DFIG协同SVG并网的4机2区域系统的控制系统模型,添加附加阻尼控制信号,控制DFIG输出的有功功率和SVG输出的无功功率,改变系统的特征根,并基于Prony方法分析振荡信号各模态。结果表明：该方法能够有效提供正阻尼,抑制系统低频振荡,加速振荡波形平息,提高电力系统的小干扰稳定性。     

一种用于卫星定位系统的宽波束圆极化天线

在卫星通信、定位设备中,为了迅速完成定位和通信功能,一般要求天线具有较大的波瓣宽度和较好的低仰角增益.研究设计了一种具有良好低仰角增益的宽波束圆极化四臂螺旋天线,该天线在上半空间的增益分布十分均匀,10°仰角的增益相对峰值增益下降不超过3 dB.为了改善天线的轴比性能,文章提出了一种四臂等幅馈电、相位依次相差90°的天线方案,仿真结果表明,这种天线的增益特性和轴比特性都得到了较大的改善.     

冰箱和冷柜能量指标的分析

本文通过对冰箱和冷柜压缩机的工况分析,得出能量指标与压缩机的匹配及开停温差的关系,并提出求最佳匹配与合理开停温差的方法.