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1.
提出一类混合参数共轭梯度法,在步长满足Wolfe线搜索的条件下,算法产生的搜索方向是下降方向.在适当的条件下,算法是全局收敛的. 相似文献
2.
《高技术通讯(英文版)》2024,30(3):322-332
Magnetic-liquid double suspension bearing(MLDSB)is a new type of suspension bearing based on electromagnetic suspension and supplemented by hydrostatic supporting.Without affecting the electromagnetic suspension force,the hydrostatic supporting effect is increased,and the real-time coupling of magnetic and liquid supporting can be realized.However,due to the high rotation speed,the rotor part produces eddy current loss,resulting in a large temperature rise and large ther-mal deformation,which makes the oil film thickness deviate from the initial design.The support and bearing characteristics are seriously affected.Therefore,this paper intends to explore the internal effects of eddy current loss of the rotor on the temperature rise and thermal deformation of MLDSB.Firstly,the 2D magnetic flow coupling mathematical model of MLDSB is established,and the eddy current loss distribution characteristics of the rotor are numerically simulated by Maxwell software.Secondly,the internal influence of mapping relationship of structural operating parameters such as input current,coil turns and rotor speed on rotor eddy current loss is revealed,and the changing trend of rotor eddy current loss under different design parameters is explored.Thirdly,the eddy cur-rent loss is loaded into the heat transfer finite element calculation model as a heat source,and the temperature rise of the rotor and its thermal deformation are simulated and analyzed,and the influ-ence of eddy current loss on rotor temperature rise and thermal deformation is revealed.Finally,the pressure-flow curve and the distribution law of the internal flow field are tested by the particle image velocimetry(PIV)system.The results show that eddy current loss increases linearly with the in-crease of coil current,coil turns and rotor speed.The effect of rotational speed on eddy current loss is much higher than that of coil current and coil turns.The maximum temperature rise,minimum temperature rise and maximum thermal deformation of the rotor increase with the increase of eddy current loss.The test results of flow-pressure and internal trace curves are basically consistent with the theoretical simulation,which effectively verifies the correctness of the theoretical simulation.The research results can provide theoretical basis for the design and safe and stable operation of magnetic fluid double suspension bearings. 相似文献
3.
Deeksha Tripathi;Saroj K. Biswas; 《Journal of forecasting》2024,43(8):3161-3176
Agriculture is facing significant challenges in the development of crop yield forecasts, which are important aspects of decision-making at the international, regional, and local levels. The area of agriculture is attracting growing attention because of increasing the demand for food supplies. To ensure future food supplies, crop yield prediction (CYP) provides the best decision-making to assist farmers in agricultural yield forecasting efficiently. Nevertheless, CYP is a difficult endeavor because of the intricacy of the underlying mechanisms and the effect of numerous factors, including weather patterns, soil characteristics, and crop management techniques. In today's era, ensemble learning (EL) approaches have recently demonstrated significant promise for enhancing the reliability and accuracy of CYP. The success of the EL techniques depends on several facts, including how the base learner models are trained and how these are combined. This study provides important insights into the EL techniques for CYP. This paper proposes an expert system model named precise ensemble expert system for crop yield prediction (PEESCYP) to predict the best crop for agricultural land. The proposed PEESCYP model employs multiple imputation by chained equation (MICE) data imputation technique to treat the missing values of the collected dataset, the isolation forest (IF) technique for outlier detection, the ant colony optimization (ACO) technique to perform feature selection, robust scaling (RS) technique to perform data normalization, and the extra tree (ET) is used for classification to overcome the variance and overfitting problem of the single classifiers. The measurements of the proposed PEESCYP model have been collected by means of accuracy, precision, recall, and F-1 score using a prepared dataset, which is collected from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), and the proposed model is compared with different single-classifier based ML models, EL models, and various existing models available in the literature. The results of this experiment underline that the proposed PEESCYP model outperforms the others. 相似文献
4.
针对自来水生产过程的原水水质评价问题,提出了一种基于PSO-RBF神经网络模型的原水水质评价方法.首先,根据水厂生产经验和历史数据分析,制定面向自来水生产过程的原水水质评价标准.然后,采用粒子群优化(PSO)算法训练的RBF神经网络模型,对苏州市相城水厂的进厂原水水质实施在线评价.最后,将进厂原水水质在线评价结果作为前... 相似文献
5.
研究一种100V-Cr-Mo钢用做石油套管材料.采用890～910℃淬火+650℃高温回火处理,使材料屈服强度达到1 150～1 160MPa、抗拉强度1 190～1 240MPa、伸长率18％～23％、冲击功102～132 J.分析表明:100V-Cr-Mo材料的调质处理组织细小、均匀,晶粒度大于9级,为回火索氏体,... 相似文献
6.
本文设计了一种复合人工蜂群算法,将细菌觅食优化算法中的趋药性行为引入到人工蜂群算法中,使得引领蜂和观察蜂进行局部探查时像细菌觅食时那样翻转到有利的方向上进行游动;另一方面,让蜜蜂尝试在所有维度产生扰动并择优选择,这两种策略大大增强了人工蜂群算法的局部探查能力.将此算法应用于训练人工神经网络,实验表明改进后的算法性能比人... 相似文献
7.
研究感知无线电网络中分布式功率控制问题.为保证对主用户的干扰低于阈值,提出一种节点本地估计和信息交换的策略,不需要中心控制节点和辅助测量节点.优化目标是在满足数据传输延迟约束条件下最小化节点的发射功率,并证明此功率控制是凸优化问题.基于拉格朗日对偶分解原理,构造了次梯度迭代的分布式算法,并证明了分布式算法的收敛性.计算... 相似文献
8.
通过钻井和油藏解剖得到,海塔盆地中部主要断陷带油藏类型除少量基岩潜山油藏外,主要为断层油藏,纵向上以南一段自生自储式生储盖组合油最富集,平面上呈11个富集区分布,以塔南中次凹和贝中-南贝尔东次凹北洼槽油更富集。油成藏可分为自生自储式、下生上储式和上生下储式3大类成藏模式,自生自储式又可分为洼中隆、缓坡断阶带和陡坡断阶带或断鼻3种成藏模式,油成藏模式对油分布的控制作用表现在3个方面:①缓坡断阶带油成藏模式是油富集的最主要成藏模式;②成藏模式越发育的的层位,油就越富集;③成藏模式越发育的地区,油也就越富集。 相似文献
9.
为了发挥一路一线直行式公交系统的优越性,针对路口信号协调控制与首末站车辆调度,提出了一路一线直行式公交系统的信号配时与车辆调度协调控制方法.该方法根据公交线路上相邻交叉口之间的距离、公交站点的分布、公交车辆的平均行驶速度、公交车站平均上下客时间、各路口的信号周期和最小绿灯时间,通过Webster方法和改进的图解法,优化... 相似文献
10.
李洪兴 《北京师范大学学报(自然科学版)》1997,(4)
继续研究数学神经网络，这里提出一种观点：人工神经网络可以作为数学的一种可视化手段．首先用例子指出几种熟知的数学方法可以用神经网络表达，然后讨论了线性规划、多目标线性规划、模糊线性规划以及模糊关系方程的神经网络形式． 相似文献