多线左旋螺纹的数控车削方法

文章以沈阳数控机床HT1625 FANUC 0I-TC系统为例,通过选用设置合理的切削参数和工艺,探讨多线左旋螺纹的数控车削加工。     

基于动态规划的电动拖拉机动力电源能量控制策略研究

针对纯电动拖拉机能量利用率低、续航里程不足的问题，提出了基于超级电容和蓄电池复合的纯电动拖拉机动力电源系统。通过分析纯电动拖拉机的作业工况特点以及功率需求，对动力电源系统进行了拓扑结构选型和参数匹配，并以动力电源能耗最低为优化目标，应用动态规划对纯电动拖拉机的动力电源系统进行能量控制策略优化，对动态规划结果以及工况特点进行分析，总结出基于规则的动力电源能量控制策略，利用Matlab/Simulink建模对控制策略进行仿真。结果表明基于动态规划的控制策略能量消耗比基于规则的控制策略能量消耗减少了18%，证明了基于动态规划的能量控制策略在节能降耗方面的有效性。     

Prematurity and Dysmaturity Are Associated With Reduced Height and Shorter Distal Limb Length in Horses

The long-term effects of gestational immaturity in the premature (defined as < 320 days gestation) and dysmature (normal term but showing some signs of prematurity) foal have not been thoroughly investigated. Studies have reported that a high percentage of gestationally immature foals with related orthopedic issues such as incomplete ossification may fail to fulfill their intended athletic purpose, particularly in Thoroughbred racing. In humans, premature birth is associated with shorter stature at maturity and variations in anatomical ratios, linked to alterations in metabolism and timing of physeal closure in the long bones. We hypothesized that gestational immaturity in horses might similarly be associated with reduced height and different anatomical ratios at maturity. In this preliminary study, the skeletal ratios of horses with a history of gestational immaturity, identified through veterinary and breeder records, were compared with those of unaffected, closely related horses (i.e., sire, dam, sibling). External measurements were taken from conformation photographs of cases (n = 19) and related horses (n = 28), and these were then combined into indices to evaluate and compare metric properties of conformation. A principal component analysis showed that the first two principal components account for 43.8% of the total conformational variation of the horses’ external features, separating horses with a rectangular conformation (body length > height at the withers), from those that are more square (body length = height at the withers). Varimax rotation of PC1 and analysis of different gestational groups showed a significant effect of gestational immaturity (P = .001), with the premature group being more affected than the dysmature group (P = .009, P = .012). Mean values for the four dominant indices showed that these groups have significantly lower distal limb to body length relationships than controls. The observed differences suggest that gestational immaturity may affect anatomical ratios at maturity, which, in combination with orthopedic issues arising from incomplete ossification, may have a further impact on long-term athletic potential.     

Reducing crude protein variability and maximizing savings when formulating corn-soybean meal-based feeds

Crude protein in corn and soybean meal have been documented to vary, and such inherent variability can result in under- or over-feeding of CP when feeds are formulated, leading to reduced bird growth, added input costs, and increased environmental pollution. The purpose of this study was to compare 2 grain-handling techniques and 2 feed formulation methods (linear vs. stochastic programming) to reduce CP variability in finished feeds and determine resulting costs or savings. The 2 grain-handling techniques were placing all the random batches of each delivered ingredient in to (1) a single bin (1-bin method) or (2) segregating above- and below-average samples into 2 bins (2-bin method). A fast way of estimating the composition of the ingredients is now available (near-infrared reflectance spectroscopy). Microsoft Excel workbooks were constructed to solve broiler starter feed formulation problems. Formulating feeds by linear and stochastic models based on the 2-bin method reduced CP variability by at least 50% compared with the 1-bin method. Formula cost was reduced by ˜20 cents per ton (averages of August 2012 United States ingredient prices) when the 2-bin method was used with the linear model. Formulating feed with a margin of safety increased formula cost by $3.40 per ton. Stochastic feed formulation increased formula cost to meet the specified CP level in feed at any probability of success, and formula cost was reduced substantially with the 2-bin method (up to $6.47 per ton). The magnitude of savings and reduced feed variability suggested that, regardless of the costs associated with building extra bins, the 2-bin method can be economically efficient in the long run. Therefore, it could be possible to split the batches of feed ingredients at a feed mill into above- or below-average bins before feed formulation to reduce CP variability and to maximize savings.     

联合收割机割刀驱动行星轮系多目标优化设计

针对联合收割机割刀机构的工作特点,采用2K-H型行星齿轮机构,分析了割刀机构工作原理。通过建立2K-H型行星轮系的优化设计模型,应用NSGA-2算法对2K-H型行星齿轮机构进行多目标优化设计。以最小体积和最大承载力为优化设计目标,通过编制MATLAB程序得到Pareto前沿,进而得到最优解,与以往多目标优化设计比较,设计得到了很好的改善。     

基于BTO多目标遗传算法的播种机性能优化设计

受播种地形和地域的影响,大部分播种机的播种质量、播种效率和能耗不能发挥到最佳状态,为了提高播种机的作业性能,深入挖掘了按顾客订单生产(Build-to-Order,BTO)模式的一般性意义,并将该模式引入到了播种机的优化设计中,提出了一种基于BTO模式的多目标速度控制遗传算法优化模型。根据播种质量、效率和能耗的要求,首先确定了BTO模式下播种机性能优化的初始参数,利用多目标函数确定了播种机的速度控制模型,并利用遗传算法进行了优化设计。最后,通过试验样机对播种机的播种性能进行了测试,结果表明:使用多目标遗传算法对播种机的性能进行优化后,播种机的播种质量、播种效率和播种能耗有了明显的改善,为新型播种机的研发提供了较有价值的参考。     

Composition of Application Based on Business Rule

In order to support flexibility and reusability of application composition based on Internet,with business rule and Aspect-Oriented Programming(AOP) which divides a business process into a control business process and a core business process,the authorsgive composition mechanism.A technique of implementation is analyzed.At last,the primary application of the above work in Chongqing of China is introduced,as well as some effects acquired.     

Descending Dimension Algorithm of Nolinear Programming Problem with Linear Inequality Constraints

The general nonlinear programming with linear constraints was investigated. In the algorithm, the method of contributing set was used. Comparing with the general contributing set method, the descending dimension method was used to solve the sub-problem with equality constraints in iterative procedure and the problem with inequality constraints. The algorithm is effective by the numerical test. Finally, it was proved that the iteration points are descending, when the objective functions are convex.     

灌溉渠系流量最优调配的0-1规划模型

本文根据灌溉配水渠系的运行特点,提出在一定轮期和来水流量限制条件下实现下级配水渠最优组合及其配水时间最优排序的一种0-1规划模型,实例运算表明,这种方法可有效减少无效弃水和闸门调节次数,同时对渠道横断面的设计有参考意义。