A CMAC-PD compound torque controller with fast learning capacity and improved output smoothness for electric load simulator

The compound architecture of CMAC (Cerebellar Model Articulation Controller) and PD (Proportional-Derivative) can effectively reduce the loading error and restrain the surplus torque of electric load simulators. But due to its generalization ability, the CMAC controller has an unsmooth output, which leads to the motor vibration even the divergence of control system. The unsmooth problem of CMAC is analyzed in this paper and a novel scalar cost function of CMAC is proposed, which consists of an error item and a weight smoothing item to guarantee fast learning capacity and improved output smoothness of CMAC. With the novel scalar cost function, a compound torque controller of PD and smooth CMAC is derived by using the gradient descent algorithm. Both the simulation and experimental results demonstrate that the novel CMAC-PD compound controller can effectively improve the output smoothness of the electric load simulator, eliminate the surplus torque and assure the stability of system as well.     

Fault-tolerant shortest connection topology design for formation control

This paper studies the fault tolerant formation keeping problem of multi-agent systems with consideration of shortest connection topology. This is motivated by the requirement of low communication cost which largely depends on the communication length. Given a formation shape, a connection topology design method and its reconfiguration strategy are proposed in the sense that the whole connection path is shortest despite of communication faults. A control framework that combines the individual formation controller of each agent and connection topology is further presented. The stability of the whole system process is analyzed by switched system theories. Simulation results of unmanned aerial vehicles (UAVs) show the effectiveness of the proposed strategy.     

Reliability analysis of structures with complex limit state functions using probability density evolution method

In reliability-based structural analysis and design optimization, there exist some limit state functions exhibiting disjoint failure domains, multiple design points and discontinuous responses. This study addresses this type of challenging problem of reliability assessment of structures with complex limit state functions based on the probability density evolution method (PDEM). Probability density function (PDF) of stochastic structures under static and dynamic loads can be acquired, which is independent of the specific form of limit state functions. Numerical results of several typical examples illustrate that, the time-invariant and instantaneous PDF curves and failure probabilities of stochastic structures with disjoint failure domains, multiple design points and discontinuous responses are calculated effectively and accurately. Moreover, the PDEM is validated to be more efficient than the Monte Carlo simulation and the subset simulation, and is a feasible and general approach to tackle the reliability analysis of complicated problems. In addition, the influence of random design parameters of structures on uncertainty propagation is also scrutinized.     

Research on the comprehensive traffic state evaluation model linked with drivers’ perception under the vehicle networking

Unified judgment standards and methods are often adopted to identify traffic state in certain road network based on traffic flow parameters. However, drivers often have different perceptions about the traffic state on different road sections, since their expectations on traffic state vary more or less from each other on different road sections. In particular, under the vehicle networking, out of considerations for safety and other relevant factors, requirements for the correlation and coordination of running vehicles have also raised significantly. Therefore, it is necessary to take driver’s perception about the driving conditions of certain road sections into consideration to adjust the release of traffic state. This paper has provided a comprehensive traffic state evaluation model linked with driver’s perception under the vehicle networking. The authors first establish an ANFIS model based on the T–S model and then conduct statistical analysis on drivers’ perceptions about certain traffic state. At last, the authors use the results of statistical analysis as regulatory factors to amend the parameters input through ANFIS. Through simulation, this paper has demonstrated that the model established has a high rate of convergence, a high identification precision and the generalization ability to conduct researches on the identification of traffic state.     

环氧化天然橡胶内胎气密性和实用性的研究

采用与ＩＲ内胎、ＮＲ内胎平行对比的方法研究了静态及装车使用条件下环氧化天然橡胶（ＥＮＲ）内胎的保压性，测试了三种橡胶内胎及胶料试样对空气的透过率。数据表明，ＥＮＲ内胎的气密性与ＩＲ内胎的气密性相近，远优于ＮＲ内胎的气密性。ＥＮＲ内胎使用性能良好，冬季在北纬４６°森林山区使用未发现不耐低温问题。３年５个月库存后外观完好，物理机械性能无明显变化     

微波烧结Al2O3-TiC复合材料的研究

以纳米级TiC、Al2 O3 为原料 ,用微波烧结制备Al2 O3 -TiC复合材料 ,并与常规烧结比较。分析了两种烧结方法对制备试样的力学性能的影响 ,并探讨了添加剂对Al2 O3 -TiC复合材料烧结性能的影响     

The effects of Ni and Li doping on the performance of lithium manganese oxide material for lithium secondary batteries

Layered Li_0.7[M_1/6Mn_5/6]O₂ (M=Li, Ni) was synthesized using a sol-gel method. P2-Na_0.7[M_1/6Mn_5/6]O₂ precursor was first synthesized by a sol-gel method, and then O2-Li_0.7[M_1/6Mn_5/6]O₂ was prepared by an ion exchange of Li for Na in P2-Na_0.7[M_1/6Mn_5/6]O₂ precursor. From charge/discharge curves, it was seen that Li_0.7[Li_1/6Mn_5/6]O₂ has two plateaus similar to those observed from a spinel structure, but Li_0.7[Ni_1/6Mn_5/6]O₂ holds a single plateau as observed from a typical layered structure. It was considered that Li_0.7[Li_1/6Mn_5/6]O₂ undergoes a phase transformation from layered to spinel structure during the charge/discharge cycle, but Li_0.7[Ni_1/6Mn_5/6]O₂ maintains O2-layered structure after the cycles. Li_0.7[Ni_1/6Mn_5/6]O₂ was higher in discharge capacity and retention rate than Li_0.7[Li_1/6Mn_5/6]O₂.     

Pt/TiO_2光催化制氢的初步研究

对无氧条件下Pt/TiO_2光催化重整甲醇制氢的基本步骤进行简化,在同一体系中进行了光催化剂的合成和光催化制氢的两步反应。基于正交设计法对该复杂体系进行了分析,得到Pt载量、甲醇/水体积、灯距、前反应时间这4种影响因素的3个不同水平对放氢速率的影响。确定了最佳实验条件为Pt载量0.5％(mol)、甲醇/水体积比5:1、灯距12 cm、前反应时间3h。分析结果表明,Pt载量对放氢速率的影响最大。实验获得的最高放氢速率为5.84 ml·h~(-1)·g~(-1)。     

透明成核剂对聚丙烯的非等温结晶行为的影响

采用热分析方法研究了透明成核剂TM-3对聚丙烯(PP)非等温结晶行为的影响,并与纯PP样品作了比较.结果表明,TM-3能够提高聚丙烯的结晶温度12℃左右;分别采用了Avrami和莫志深方法对非等温结晶过程作了分析处理;对含有成核剂的PP样品的非等温结晶行为分析显示,成核剂的加入改变了聚丙烯的结晶行为,使其成核与结晶生长过程复杂化.