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排序方式: 共有1500条查询结果,搜索用时 437 毫秒
551.
552.
柴油机SCR催化器载体结构参数优化 总被引:2,自引:1,他引:1
提出一种柴油机选择催化还原(SCR)催化器载体结构参数优化的设计方法,根据车用柴油机排量,将SCR催化器载体分为4类,选取载体体积、长度、目数、壁厚和涂层厚5个结构参数为设计变量,以高NO。转化率及低压力损失为优化目标,利用拉丁超立方实验设计选择样本点进行数值模拟,在构建的Kriging近似模型基础上,对载体结构参数采用改进的非支配排序遗传算法NSGA—II(non—dominatedsortinggeneticalgorithm—II)进行优化设计。结果表明:Kriging近似模型的拟合精度较高,结合NSGA—II算法对SCR催化器载体结构参数进行优化是可行的、有效的,不同排量下的优化结果均能够较好地满足设计要求。 相似文献
553.
Li Ning 《中国人口.资源与环境(英文版)》2012,(2):51-59
China's circular economy is still at the initial stage, whose development has many difficulties and problems requiring immediate resolution theoretically and practically. Due to the differences of regions on the scale of land, endowment of resources, economic basis and cultural background, the developmental levels and capabilities of circular economy are inevitably different. Based on establishing the indicator system for assessing the developmental level of regional circular economy, spatial variation of China's circular economy is measured by the quantitative measurement using principal component analysis, and the existing problems are also analyzed and discussed. On one hand, the differences of the development capability of the circular economy of different provinces (cities) are profound in China; ①Difference between the first category (strong) and the second category (relatively strong) is 1.1264 points. Difference between the second category and the third category (relatively weak) is 0.3867 points. Difference between the third category and the fourth category (weak) is 1.0238 points. Difference between the first category and the fourth category reaches up to 2.0869 points. Average difference between the area where the developmental level of circular economy is relatively strong and the area where the developmental level of circular economy is relatively weak is 1.3617 points. ②The differences of the distribution of the areas, with different development capability of circular economy, which are located in the three economic regions of China, are also profound. The regions with a relatively strong development capability of circular economy are mainly located in the eastern economic area, which account for 22.58% of the whole regions, while only account for 12.90% in the middle and western economic areas. On the contrary, the regions with a relatively weak development capability of circular economy account for 48.39% in the middle and western area, while account for 16.13% in the eastern area. On the other hand, among regions with different development capability of circular economy, the regions with a relatively weak development capability of circular economy are in a dominant position, which accountfor 64.52% of all the provinces (cities), which indicates that the development of the China's circular economy still has a long way to go. Though certain achievements have been made in the development of China's circular economy, in general, there are still some obstacles to be tacked in the development of China's circular economy which require the economic, legal and administrative methods. 相似文献
554.
将大涡模拟法与Lighthill-Curle声学比拟理论相结合,计算了高速列车纵向对称面的气动噪声,探明了纵向对称面气动噪声的频谱特性及其变化规律,得出了车辆连接处的优化外形。结果表明,低频时,气动噪声幅值较大,随着频率升高,幅值下降。当列车运行速度一定时,距离气动噪声源越远,声压的衰减幅度越少。随着列车运行速度增加,距离气动噪声源越远,声压的增幅越小。脉动压力是气动噪声的源,在车辆连接处采用平滑的Nurbs曲线过渡,以减少列车运行过程中产生的脉动压力,能有效降低气动噪声。 相似文献
555.
在含油污泥进行资源化处理过程中,针对处理目标受多个因素影响的实际,为了解决工艺之间的耦合问题,采用正交实验的方法来解决,并把主要参数作为优化对象,把含油污泥的脱水率作为评价目标,通过采用GA-BP算法对含油污泥耦合工艺正交实验参数进行了线性与非线性分析.在采用遗传算法优化神经网络的权值和阈值的基础上,用优化后的权值和阈值对测试样本和训练样本进行了预测.预测结果表明,预测误差都有明显减小,分别由0.34211减少到0.031549和0.15476减少到0.040682,可见耦合参数趋向于非线性优化. 相似文献
556.
To improve the competiveness in the energy market, it is necessary that the wind power plants provide guaranteed power generation, although, it is not possible to forecast power availability from wind power plant accurately. This paper presents a stochastic model and solution technique for the combined operation of wind and pumped storage power plants to improve the power availability and increasing the profit considering uncertainties of wind power generation. In this model, uncertainties in wind data have been forecasted for grid connected day-ahead market using Weibull distribution model. The imbalances in the forecasted wind data and the market demand have been reduced by operating the pumped storage power plant. In this stochastic mixed integer problem, pumped storage plant can take the supply either from the grid or from the wind power plant for the pumping operation to store the energy in order to utilize this energy during peak hours for increasing the overall revenue. The reliability of the pumped storage is improved by replacing the conventional unit with the adjustable speed type pumped storage unit. In order to prove the optimality of the solution, two case studies were considered. In case study–I, scheduling is provided by operating the conventional pumped storage unit, whereas in case study–II, adjustable speed pumped storage unit has been used. It has been found that the adjustable speed pumped storage unit has further reduced the imbalance between generated power and demand. The complete approach has been formulated and implemented using AMPL software. 相似文献
557.
558.
从地表水突发污染应急处置实际需求的角度,考虑纤维材料的现场实用性,研究了均苯四甲酸二酐改性黄麻的制备过程及对重金属铜离子的吸附性能,吸附等温线、吸附动力学和吸附热力学。通过正交实验对改性条件进行了优化,结果表明,反应物(黄麻与酸酐)配比和反应温度对改性黄麻的吸附量有十分显著的影响;在室温,p H为5~7的条件下,改性黄麻对铜离子的吸附容量为43.56 mg/g,比原态黄麻提高了7倍多;改性黄麻对铜离子的吸附符合Langmuir模型,为单分子层吸附;吸附过程是符合假二级动力模型的自发吸热反应。 相似文献
559.
在CFD软件Fluent中,选择k-ε湍流模型,多孔介质模型和SIMPLE算法,对新型脱硫脱硝脱汞反应塔内的三维流场进行数值模拟,结果发现,反应塔入口处烟气流场存在大漩涡。为消除漩涡,使穿过活性焦层的烟气均匀化,以充分利用活性焦层的空间来提高脱除效率,提出在入口处加装弯曲导流板,并通过相对标准偏差确定最优导流板长度。同时模拟了在最优喷氨位置处加装涡旋混合器时氨气和烟气的混合情况。结果表明,最优导流板长度(3.6 m)明显改善了烟气的均匀性,促使入口处的压降下降100 Pa左右。涡旋混合器形成的小漩涡,增强了烟气和氨气的混合。最后对照不同流量下实验值和模拟值的压降变化,验证了多孔介质模型的可行性。模拟结果对设备的优化设计和实际运行具有指导作用。 相似文献
560.
降水中与pH值有关的离子优选和pH值的PPR预测 总被引:3,自引:0,他引:3
应用投影寻踪回归(PPR)分析技术的SMART算法得到因子的权重序列,可实现对降水中与酸性pH值有关的离子的优选。实例分析结果表明,用优选出的离子作为特征因子,建立pH值的投影寻踪回归预测模型,具有较高的预测精度和较好的稳定性 相似文献