以钛酸丁酯作为TiO_2的前驱体,利用硝酸镧和硫脲作为掺杂源,采用溶胶-凝胶法制备了La、N/S共掺杂TiO_2光催化剂,并采用紫外-可见分光光度计(UV-Vis)和X射线衍射仪(XRD)对所制备的光催化剂进行了分析表征,然后利用Fenton试剂氧化法预处...以钛酸丁酯作为TiO_2的前驱体,利用硝酸镧和硫脲作为掺杂源,采用溶胶-凝胶法制备了La、N/S共掺杂TiO_2光催化剂,并采用紫外-可见分光光度计(UV-Vis)和X射线衍射仪(XRD)对所制备的光催化剂进行了分析表征,然后利用Fenton试剂氧化法预处理与太阳光催化氧化法联合对造纸黑液进行了降解处理,分别考察了光照时间、光催化剂用量、处理液p H值、H_2O_2加入量等各因素对光催化降解率的影响,在单因素研究的基础上进行了L9(3~4)正交试验。结果表明,所制备的共掺杂TiO_2为锐钛矿晶型,吸收带红移有较强的可见光吸收,大大提高了对太阳光能的利用率。造纸黑液经Fenton试剂氧化预处理后,在500 W氙灯(模拟太阳光)下光催化氧化降解的最佳工艺条件为:50 m L造纸黑液,H_2O_2加入量为0.6 m L;反应液p H=5;光照时间90 min;催化剂用量0.04 g,在上述工艺条件下太阳光催化降解率可达到73%,处理效果大大优于市售进口TiO_2光催化剂和单一光催化降解过程。展开更多
The impact angle control over guidance(IACG) law against stationary targets is proposed by using feedback linearization control(FLC) and finite time control(FTC). First, this paper transforms the kinematics equation o...The impact angle control over guidance(IACG) law against stationary targets is proposed by using feedback linearization control(FLC) and finite time control(FTC). First, this paper transforms the kinematics equation of guidance systems into the feedbackable linearization model, in which the guidance law is obtained without considering the impact angle via FLC. For the purpose of the line of sight(LOS) angle and its rate converging to the desired values, the second-order LOS angle is considered as a double-integral system. Then, this paper utilizes FTC to design a controller which can guarantee the states of the double-integral system converging to the desired values. Numerical simulation illustrates the performance of the IACG, in contrast to the existing guidance law.展开更多
Hydrostatic spindles are increasingly used in precision machine tools. Thermal error is the key factor affecting the machining accuracy of the spindle, and research has focused on spindle thermal errors through examin...Hydrostatic spindles are increasingly used in precision machine tools. Thermal error is the key factor affecting the machining accuracy of the spindle, and research has focused on spindle thermal errors through examination of the influence of the temperature distribution, thermal deformation and spindle mode. However, seldom has any research investigated the thermal effects of the associated Couette flow. To study the heat transfer mechanism in spindle systems, the criterion of the heat transfer direction according to the temperature distribution of the Couette flow at different temperatures is deduced. The method is able to deal accurately with the significant phenomena occurring at every place where thermal energy flowed in such a spindle system. The variation of the motion error induced by thermal effects on a machine work-table during machining is predicated by establishing the thermo-mechanical error model of the hydrostatic spindle for a high precision machine tool. The flow state and thermal behavior of a hydrostatic spindle is analyzed with the evaluated heat power and the coefficients of the convective heat transfer over outer surface of the spindle are calculated, and the thermal influence on the oil film stiffness is evaluated. Thermal drift of the spindle nose is measured with an inductance micrometer, the thermal deformation data 1.35 μm after running for 4 h is consistent with the value predicted by the finite element analysis’s simulated result 1.28 μm, and this demonstrates that the simulation method is feasible. The thermal effects on the processing accuracy from the flow characteristics of the fluid inside the spindle are analyzed for the first time.展开更多
文摘以钛酸丁酯作为TiO_2的前驱体,利用硝酸镧和硫脲作为掺杂源,采用溶胶-凝胶法制备了La、N/S共掺杂TiO_2光催化剂,并采用紫外-可见分光光度计(UV-Vis)和X射线衍射仪(XRD)对所制备的光催化剂进行了分析表征,然后利用Fenton试剂氧化法预处理与太阳光催化氧化法联合对造纸黑液进行了降解处理,分别考察了光照时间、光催化剂用量、处理液p H值、H_2O_2加入量等各因素对光催化降解率的影响,在单因素研究的基础上进行了L9(3~4)正交试验。结果表明,所制备的共掺杂TiO_2为锐钛矿晶型,吸收带红移有较强的可见光吸收,大大提高了对太阳光能的利用率。造纸黑液经Fenton试剂氧化预处理后,在500 W氙灯(模拟太阳光)下光催化氧化降解的最佳工艺条件为:50 m L造纸黑液,H_2O_2加入量为0.6 m L;反应液p H=5;光照时间90 min;催化剂用量0.04 g,在上述工艺条件下太阳光催化降解率可达到73%,处理效果大大优于市售进口TiO_2光催化剂和单一光催化降解过程。
基金supported by the National Natural Science Foundation of China(51679201)
文摘The impact angle control over guidance(IACG) law against stationary targets is proposed by using feedback linearization control(FLC) and finite time control(FTC). First, this paper transforms the kinematics equation of guidance systems into the feedbackable linearization model, in which the guidance law is obtained without considering the impact angle via FLC. For the purpose of the line of sight(LOS) angle and its rate converging to the desired values, the second-order LOS angle is considered as a double-integral system. Then, this paper utilizes FTC to design a controller which can guarantee the states of the double-integral system converging to the desired values. Numerical simulation illustrates the performance of the IACG, in contrast to the existing guidance law.
基金supported by National Natural Science Foundation of China (Grant Nos. 51105005, 51275014)Ministry of Education of China (Grant No. 20111103120002)
文摘Hydrostatic spindles are increasingly used in precision machine tools. Thermal error is the key factor affecting the machining accuracy of the spindle, and research has focused on spindle thermal errors through examination of the influence of the temperature distribution, thermal deformation and spindle mode. However, seldom has any research investigated the thermal effects of the associated Couette flow. To study the heat transfer mechanism in spindle systems, the criterion of the heat transfer direction according to the temperature distribution of the Couette flow at different temperatures is deduced. The method is able to deal accurately with the significant phenomena occurring at every place where thermal energy flowed in such a spindle system. The variation of the motion error induced by thermal effects on a machine work-table during machining is predicated by establishing the thermo-mechanical error model of the hydrostatic spindle for a high precision machine tool. The flow state and thermal behavior of a hydrostatic spindle is analyzed with the evaluated heat power and the coefficients of the convective heat transfer over outer surface of the spindle are calculated, and the thermal influence on the oil film stiffness is evaluated. Thermal drift of the spindle nose is measured with an inductance micrometer, the thermal deformation data 1.35 μm after running for 4 h is consistent with the value predicted by the finite element analysis’s simulated result 1.28 μm, and this demonstrates that the simulation method is feasible. The thermal effects on the processing accuracy from the flow characteristics of the fluid inside the spindle are analyzed for the first time.
