一次近似下的非线性减振器的分岔分析

通过对一类内共振条件下的非线性减振器的数学模型进行分析,得到了一次近似下动力学的响应方程。发现系统存在有两类平衡解,平衡解的进一步失稳导致分岔现象的产生。揭示了阻尼、固有频率、激励频率等系统参数对其动力学行为的影响规律,给出了减振效果相对较好的参数条件,进而提出改善减振器效果的措施。     

高职院校英语应用型人才培养模式之于听力教学

高职院校英语应用型人才培养问题一直是比较受关注的问题,应用型特征愈加明显。该文着重从目前高职院校顺应应用型人才培养模式下英语听力教学中存在的问题,提出听力教学方法改革的途径,旨在从英语听力教学改革的角度,加强对英语应用型人才的培养。将英语专业课程分为英语专业技能、英语专业知识和相关专业知识是高职院校对英语专业英语教学的要求,英语教学既要注重培养英语的基本功底,同时又要注重开拓学生的人文学科知识和科技知识,注重培养学生获取知识、独立思考以及创新的能力。     

Removal of Microcystin-LR in Water by Chlorine Dioxide

Microcystins(MCs)are well known as hepatotoxins produced by blooms of toxic cyanobacteria(blue-green algae) abundant in surface water used as drinking water resource and have drawn attention of environmentalists world over by leading to adverse health effects.A study on efficiency and reaction kinetics of microcystin-LR(MC-LR)degradation by ClO2 was performed. Experimental results indicated that MC-LR was removed by ClO2 effectively and the residual concentration of MC-LR could meet the national guideline(GB5749-2006)(1.0 μg·L-1 ),the efficiency of removal was in positive correlation to ClO2 dosage and reaction time and in negative correlation to initial concentration of MC-LR and pH value, whereas it was affected by temperature slightly.ClO2 dosage was the most important reaction factor on base of the orthogonal test results.The reaction was second order overall and first order with respect to both ClO2 and MC-LR,and had an activation energy of 78.81 kJ · mol-1.The reaction rate constant was 4.74×102 L/(mol·min) at 10 ℃.Therefore, oxidation of ClO2 could be taken as an effective technology for removing MC-LR from drinking water resources in traditional drinking water supplies.     

非零平衡强非线性van der Pol系统的奇异性分析及分岔

探讨一类非零平衡强非线性van der Pol系统奇异和分岔特性．首先将系统转化为平面向量场,分析了各种不同平衡点存在的参数条件,得到了参数空间中的转迁集,进而将参数空间划分为不同的区域,揭示了其各种不同的分岔模式．     

环境中多环芳烃(PAHs)去除方法的研究

多环芳烃是一类广泛分布于环境中的有毒有害污染物,由于其较强的致癌性及在环境中的稳定性而一直受到研究者的关注.介绍了近年来多环芳烃污染物去除方法的研究现状,包括自然降解法、生物修复法、UV光解法、吸附法、高级氧化法及超声分解法等.并对未来多环芳烃去除技术的发展方向进行了展望.     

“地球客”拜访神秘土星

经过长达6年零8个月、35.2亿千米的漫长太空旅程,土星探测器“卡西尼”于7月1日上午终于到达目的地——土星。