排序方式: 共有47条查询结果,搜索用时 15 毫秒
1.
针对农机的电液伺服转向系统,为了克服转向力对系统的影响,提高在各种路况下的跟踪精度,设计了一种基于负载力观测器的前馈和最优状态反馈控制复合控制策略。先采用Luenberger观测器对负载力进行在线估计,然后用线性二次型调节器(LQR)得到系统线性最优反馈控制律,最后把观测到的负载力前馈到系统输入来消除负载力的影响,提高伺服系统精度。仿真和试验结果表明,所设计的负载力观测器能迅速地跟踪实际值,基于观测器的前馈和最优状态反馈复合控制策略具有较高的跟踪精度和抗负载干扰能力。 相似文献
2.
3.
4.
5.
为了研究Fe-Mn-Al-C低密度钢脱氧合金化夹杂物的生成及机理,采用Si、Mn、Al进行脱氧合金化,通过场发射扫描电子显微镜结合夹杂物自动分析系统对Fe-Mn-Al-C低密度钢样品中的夹杂物进行观察。结果显示,Fe-Mn-Al-C低密度钢中夹杂物主要分为6类,即单颗粒Al2O3夹杂物、单颗粒MnS夹杂物、单颗粒AlN夹杂物、Al2O3-MnS复合夹杂物、AlN-MnS复合夹杂物、Al2O3-AlN-MnS复合夹杂物。单颗粒的Al2O3、MnS、AlN夹杂物的数量相对较多,夹杂物尺寸以小于5μm为主。热力学计算发现Al2O3在脱氧合金化时生成,AlN在固相分数为0.844时开始析出,而MnS在完全凝固后的固相钢中开始析出。不同夹杂物间的二维晶格错配度计算结果显示,MnS(110)/Al2O3(001)、AlN(001)/Al<... 相似文献
6.
7.
9.
The combined effects of pre-deformation and pre-aging on the mechanical properties of AlCu-Mg alloy with Sc and Zr addition were investigated. It is revealed that the introduction of pre-deformation can enhance the peak-aging strength, as well as tensile and yield strength, effectively due to the formation of finer and more dispersive precipitation. Pre-aging process before pre-deformation can increase the elongation while maintaining higher strength with a discontinuous distribution of precipitates at grain boundary. The precipitates of bean-like Al3(Sc, Zr) particles further strengthen the alloy via pinning the dislocations which are formed during pre-deformation process and hindering the dislocation motion. Furthermore, pre-deformation and pre-aging accelerate the kinetics of precipitation due to preferential sites provided by the dislocation and the increase of GPB zones' size and distribution. The synergism of pre-deformation and pre-aging achieves a combination of better mechanical properties and shorter peak-aging time. 相似文献
10.
为研究调质处理对R4s (22MnCrNiMo)级系泊链钢闪光焊焊缝区力学性能的影响,通过改变循环淬火温度(880~960 ℃),确定最优淬火温度;然后通过改变回火温度(560~640℃)和回火后保温时间(2040 min),研究回火温度和回火后保温时间对钢力学性能的影响。结果表明,经调质处理后,焊缝区断口虽仍呈现韧性断裂,但拥有较高的强度和较好的塑性,特别是在920 ℃ 30 min+920 ℃ 30 min淬火+600℃30 min处理后,焊缝区拥有较高的强度和最佳的塑性,强度达到1 071 MPa,延伸率高达17%,综合性能最优。 相似文献