Robust pole assignment for incomplete nonlinear decoupling applied to robots

A robustness analysis and synthesis for incomplete nonlinear decoupling for a class of nonlinear systems is discussed. Rigid and elastic-joint robot models belong to this class. For the elastic case, a transformation facilitates the robustness analysis under a weak assumption. Charts with H ₁- and H - norms of closed-loop disturbance transfer functions of the nonlinear-decoupled system are presented for a robust pole assignment.     

金安金沙江悬索桥隧道式锚碇变形破坏机制研究

隧道式锚碇的变形破坏机制涉及到结构与围岩的协同作用问题。以华丽高速公路金安金沙江悬索桥两岸隧道锚变形破坏机制为研究对象,利用工程类比法评价了其稳定性控制要素,设计了超载数值试验。根据塑性区的扩展过程确定了施工安全监测和需要采取预加固的重点部位,确定了隧道锚围岩的破坏模式。根据锚面监测点位移由mm到cm量级突变确定的两岸锚岩系统极限荷载均为6~8倍设计缆力,则锚岩系统的设计承载力取3倍设计缆力下变形安全是有保障的。丽江岸塑性区在10 P下贯通;华坪岸塑性区在14 P下贯通。设计缆力作用下,丽江岸锚碇最大位移1.5 mm、围岩1.2 mm、地表0.5 mm;华坪岸锚碇最大位移1.7 mm、围岩1.5 mm、地表0.7 mm,其响应顺序为后锚面监测点前锚面监测点锚碇中间岩体地表点,可作为后期结构及围岩安全监测布点和预警的参考,也证明当前设计缆力下变形和强度均是安全的。     

Dynamic response of Ti3SiC2 under shock compression up to 112 GPa

Ti₃SiC₂ is of interest due to its unique dual nature reminiscent of both brittle ceramics and ductile metals at ambient conditions. In this work, plate-impact experiments have been performed to study the dynamic behavior of Ti₃SiC₂ under shock compression up to 112 GPa by using laser velocity interferometer and electric pin techniques. Hugoniot elastic limits (HEL), spall strength, and Hugoniot equations of state have been obtained based on measured particle velocity profiles and shock wave velocities. The ratio of spall strength to HEL for Ti₃SiC₂ is larger than brittle ceramics but smaller than metals. This result indicates that the dual nature of Ti₃SiC₂ remains at least up to 10 GPa. On the other hand, the linearity of the Hugoniot equation of state, $D=6.9\text{0}1(22)+1.153(53)u_{\text{p}}$, suggests that the initial structure of Ti₃SiC₂ should be stable up to 112 GPa, in contrast to the result reported by Jordan et al. [J. Appl. Phys., 93 (2003) 9639].     

GCr15轴承钢连铸过程中热物性参数的研究

借鉴前人实验数据,采用一定的数学方法,对轴承钢的热物性参数进行了研究.结果表明：GCr15轴承钢的液相线温度为1 465.7℃,固相线温度为1 328.4℃,零强度温度为1 380℃左右,零塑性温度为1 330℃左右;在固相区、液固两相区、液相区分别采用不同的公式进行处理,可使结果更加准确,还避免了奇异性.研究结果可为轴承钢连铸工艺有限元模拟提供基础.     

螺纹桩在软弱地层中的应用

分析了螺纹桩的受力机理,探讨了螺纹桩单桩承载力的确定方法,指出螺纹桩单桩承载力高、节约材料显著、能充分利用地基土的特性,在软弱地层中的应用优势显著,并通过实际工程实例给予具体说明.     

Experimental study on temperature stress calculation and temperature control optimization of concrete based on early age parameters

Temperature control curve is the key to achieving temperature control and crack prevention of high concrete dam during construction,and its rationality depends on the accurate measurement of temperature stress.With the simulation testing machine for the temperature stress,in the present study,we carried out the deformation process tests of concrete under three temperature curves：convex,straight and concave.Besides,we not only measured the early-age elastic modulus,creep parameters and stress process,but also proposed the preferred type.The results show that at early age,higher temperature always leads to greater elastic modulus and smaller creep.However,the traditional indoor experiments have underestimated the elastic modulus and creep development at early age,which makes the calculated value of temperature stress too small,thus increasing the cracking risk.In this study,the stress values of the three curves calculated based on the strain and early-age parameters are in good agreement with the temperature stress measured by the temperature stress testing machine,which verifies the method accuracy.When the temperature changes along the concave curve,the law of stress development is in consistent with that of strength.Under this condition,the stress fluctuation is small and the crack prevention safety of the concave type is higher,so the concave type is better.The test results provide a reliable basis and support for temperature control curve design and optimization of concrete dams.     

谈谈水泥土挡墙的合理计算

阐述了水泥土挡墙在工程基坑支护中的作用,并结合工程实例,对水泥土挡墙的合理计算模型进行了探讨。     

超声电机驱动的锁紧装置锁效果的试验研究

为了评价超声电机驱动的磁悬浮飞轮锁紧装置的锁紧效果,对锁紧装置弹片开展了试验研究.将锁紧弹片简化为悬臂梁模型,通过测试其根部应力,计算出其端部的变形量大小,进而获得弹片沿径向对飞轮转子的锁紧力大小.试验表明:每个弹片沿飞轮径向产生17.06 N的锁紧力,在250 s内完成锁紧.对比超声电机驱动与电磁电机驱动的锁紧装置,锁紧力大小相似.试验证明:超声电机驱动的锁紧装置能代替电磁电机完成锁紧和解锁功能,为超声电机在磁悬浮飞轮系统中的进一步应用提供了可能.     

基于机智云平台的滚动轴承在线监测系统

设计了一种基于云平台的滚动轴承在线监测系统,信号采集模块将振动传感器输出的振动信号进行变换,再通过有源滤波模块处理后交给控制器,控制器内部进行A/D采样,随后处理器对A/D采样后的信号进行参数的运算,最后将参数通过云平台传输协议模块,在利用WiFi转发给远程机智云平台服务器.该系统为滚动轴承的监测提供了一个平台,在这个平台上工程人员可以通过远程的云服务器和APP终端对滚动轴承的状态进行了解,很大程度上减少了工程人员的工作量,提高了对滚动轴承监测的效率.