加强实验教学过程管理促进实验教学目标达成

实验教学目标的达成依赖于严格的实验过程的科学管理。本文介绍了大连理工大学基础化学实验中心通过《化学实验指导手册》的编制和严格执行,培养学生的实验安全环保意识,加强对实验过程的指导。将实验各环节纳入考核范畴,目的在于着力培养学生良好的实验习惯,规范实验报告撰写和提高学生的创新思维能力,从而有效地监控和保证了实验教学质量。     

Liquid crystals alignment with PbS nanosculptured thin films

Lead sulphide (PbS) nano-sculptured thin films (nSTFs) are prepared for the first time using glancing angle deposition technique by physical vapour deposition process. An anisotropic morphology is obtained, which provides an orientational effect. Due to this anisotropic nature of PbS nSTF an attempt has been made to check its effect on the alignment of nematic liquid crystals (LCs). Two different LC devices were fabricated, that is, anti-parallel aligned or electrically-controlled birefringence and hybrid twisted nematic. It is noticed that in both types of devices, good alignment is obtained with high extinction and contrast. A significant effect of these alignments on the electro-optic properties of the LC is reported such as the threshold voltage, response time and contrast ratio.     

基于互动反馈教学系统的无机化学课堂教学改革

针对基础无机化学教学存在的普遍问题,在课堂教学中引入互动反馈教学系统。重点从课堂设计、课堂互动模式、课后测试、课程分析总结等4个方面介绍了课堂互动反馈教学系统的具体应用;互动教学模式对无机化学教学的促进作用显著,整个学期平均到课出勤率达到99%,95%以上的学生认为这种互动教学方式能活跃课堂气氛,激发学习兴趣,愿意接受基于课堂投票表决器构建的互动教学模式。     

Investigation and optimization of the recovery of coal fines using oil agglomeration process: Use of waste oils from different sectors

The high cost of the bridging liquid subdues the implementation and commercialization of oil agglomeration process. To overcome this problem, waste oils from different sectors were used in this present study. The performance of the process was assessed based on the responses like ash rejection and organic matter recovery. The aim of the present study was to investigate the usage of waste oils from different sectors and to optimize and analyze the behavioral pattern showcased by different variables (pulp density, oil dosage, agglomeration time and oil type) using response surface methodology (Box-Behnken design). Experimental investigation shows that the optimum pulp density, oil dosage, agglomeration time and oil type condition obtained as 3%, 15%, 15?min and waste engine oil, respectively. At optimum condition, the % ash rejection and % organic matter recovery obtained as 63.94% and 81.8%, respectively.     

Enhanced visible light photocatalysis of TiO2 by Co-modification with Eu and Au nanoparticles

TiO₂ photocatalysis has been studied widely in environment protection and energy generation applications. But, the intrinsic absence of visible light response and the high recombination rate of photo-generated charge carriers significantly limited the efficiency of photocatalysis with TiO₂ materials. Herein, a facile approach was constructed to develop visible-light-induced TiO₂ photocatalysis by co-modification with Eu and Au nanoparticles. The synthesized Au/Eu-TiO₂ material was characterized by XRD, SEM, TEM, DRS, XPS, and N₂ adsorption measurements. Visible light catalytic performance of the Au/Eu-TiO₂ catalyst was evaluated by using the photodegradation of RhB as a model reaction. It was shown that this Au/Eu-TiO₂ exhibited a better photocatalytic activity than the single Au modified TiO₂ (Au/TiO₂) or the single Eu modified TiO₂ catalyst (Eu/TiO₂), and also exhibited a good reusability for the targeted reaction. This remarkably improved performance of Au/Eu-TiO₂ could be attributed to the synergetic effect of Eu and Au co-decoration, which not only enhanced visible light absorption but also promoted charge carriers transfers as evidenced by DRS, XPS and transient photocurrent spectra. Moreover, a possible reaction mechanism for the Au/Eu-TiO₂ photocatalysis was proposed.     

Chaotic transients in surface-stabilized smectic C* cells induced by magnetic field

Recent theoretical developments regarding the understanding of weakly chaotic transients in ferroelectric liquid crystals (FLCs), induced by electric field, are studied in terms of the interaction with magnetic field. Our research is related with the nonlinear dynamical system represented by a thin film of surface-stabilized FLC in smectic C* phase, and subjected by the swinging magnetic field. The computation of the Lyapunov exponents from the dynamic equation for the director field reveals that the director dynamics exhibits limit cycle, hyperchaotic attractor and strange attractor behavior in the dissipative nonlinear media. The transients between director’s phase space trajectories can be handled by the magnetic field parameters. The fundamental understanding of the director dynamics may have a valuable contribution to the applications of thin liquid crystal films.     

冲击响应谱分析的实现方法

现从冲击响应谱的概念着手,在分析了单自由度振动系统的特性之后,通过方案比较,从理论上导出了利用TMS320C25的快速运算特性并通过FFT细化实现冲击响应谱分析的算法,为编制冲击响应谱分析软件及进一步开发先进的冲击响应谱分析仪提供了一种可靠的方法。     

轧机主传动机电耦合系统瞬态响应计算机仿真

针对轧机主传动机电耦合系统扭振的瞬态响应求解提出了一种计算机仿真方法。首先建立轧机机电耦合系统的物理模型,在此模型的基础上建立数学模型;然后将此数学模型用状态方程表达,确定系统各种模型参数广义质量矩阵［Ｍ］,广义刚度矩阵［Ｋ］,广义阻尼矩阵［Ｃ］和初始条件;最后应用四阶龙格－库塔法,计算出瞬态响应的仿真结果,将各种仿真曲线显示在屏幕上或打印出来。使用Ｔｒｕｅ－Ｂａｓｉｃ语言编制实现四阶龙格－库塔法的计算机仿真软件,并对此方法的步长的确定进行了详细的讨论,得出确定合理步长的计算公式。通过对１１５０初轧机主传动系统上轴系机电耦合系统瞬态响应的仿真计算,证实了计算机程序的正确性。     

一种控制高层结构随机地震反应的新策略

以某高层剪切型钢框架结构为工程背景,提出TMD与LRB联合作用的T-L控制策略,利用非线性随机振动理论分别对无控制、TMD控制和T-L控制3种控制结构的非线性运动方程进行等效线性化处理,利用复模态理论给出以第一振型表示的3种控制结构随机地震反应解析解的计算方法。研究结果表明:新提出的T-L控制策略比TMD控制更能显著降低结构位移、速度和加速度反应方差;新算法同样可用于求解LRB层间隔震高层结构随机地震反应。算例在T-L控制下的最大位移、速度和加速度反应方差比TMD控制下的分别降低了29.3%、27.8%和31.6%。