介绍一本流体力学教科书——《物理流体力学》

《物理流体力学》(Modormack P.D.& Crane L., 《Physical Fluid Dyna(?)mics》,Academic,1973)一书对现代流体力学作了简明扼要的介绍,是作者们在爱尔兰和美国执教多年的基础上写成的,主要内容是牛顿粘性流体。书中强调流体力学问题的物理方面,因而书名冠以“物理”二字,以与通常的流体力学的数学理论相区别。      

儿茶酚胺类神经递质在锇配位聚合物和Nafion双层膜修饰碳基电极上的电催化氧化及其痕量测定

多巴胺（ＤＡ）、肾上腺素（ＥＰ）和去甲肾上腺素（ＮＥ）等儿茶酚胺类神经递质是生物分子电化学研究的重要对象之一［１,２］．它们在固体电极上的电子传递速率非常缓慢,且其本身或反应产物易在电极表面吸附,导致电极表面的钝化［３］．利用具有特定功能的化学修饰电...     

氡—居室中的隐蔽杀手

放射性稀有元素氡，是严重的公害之一。它随时能被人吸入体内并继续发生放射性衰变，从而诱发肺癌。预防居室氡对健康的伤害必须引起重视。     

注重统计思想的现代工科概率统计教学方法

指出了工科概率统计教学中长期存在而又被忽视的一个问题,即学生的统计计算能力有余而对于统计思想、统计方法的理解与使用不足.并尝试着提出了注重统计思想的现代统计教学方法.     

不动点理论与里卡提方程两个正周期解的存在性

利用压缩映射原理,得到里卡提方程一个正周期解的存在性;利用变量变换方法,将里卡提方程转化为伯努利方程.根据伯努利方程的周期解和变量变换,得到里卡提方程的另一个周期解.并讨论了两个正周期解的稳定性,一个周期解在某个区间上是吸引的,另一个周期解在R上是不稳定的.     

如何在小组合作中进行纠错的探究

小组合作又称为合作学习,指在课堂教学过程中依学生的认知水平、个性特征、能力倾向或性别等差异组合成3~6人的学习小组,通过小组合作实现每个成员的预期学习目标.这种方式绕开了传统课堂教学中存在的一些弊端,由教师单向的授课转变为师生、生生间更多的合作与交流,既体现了以学生为主体的数学课堂教学,又提高了学生的学习效率,实现了小组成员的共同进步与成长.俗话说:"金无足赤,人无完人."错误是每个学习者难免会碰到的,如何在初中数学课堂教学中通过小组合作学习帮助他人纠正各种错误,是每个师生都值得探究的问题.     

例谈反比例函数的综合应用

聪明、细心的同学会发现,在日常生活中存在着许多两个量之间具有反比例关系的例子,学习数学的目的是“学以致用”,现从反比例函数与一次函数、不等式、简单的几何知识、相关物理知识的综合应用这些方面举例分析,供同学们参考.     

Metamorphic InGaAs p-i-n Photodetectors with 1.75 μm Cut-Off Wavelength Grown on GaAs

Top-illuminated metamorphic InGaAs p-i-n photodetectors （PDs） with 50% cut-off wavelength of 1.75 μm at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy system. The large lattice mismatch strain is accommodated by growth of a linearly graded buffer layer to create a high quality virtual InP substrate indium content in the metamorphic buffer layer linearly changes from 2% to 60%. The dark current densities are typically 5 × 10^-6 A/cm^2 at 0 V bias and 2.24 × 10^-4 A/cm^2 at a reverse bias of 5 V. At a wavelength of 1.55 μm, the PDs have an optical responsivity of 0.48 A/W, a linear photoresponse up to 5 mW optical power at -4 V bias. The measured -3 dB bandwidth of a 32 μm diameter device is 7 GHz. This work proves that InGaAs buffer layers grown by solid source MBE are promising candidates for GaAs-based long wavelength devices.     

Characteristics of a Novel Water Plasma Torch

Relying on heat generated by plasma arc heating liquid water into steam as a swirl gas, a water plasma torch has the distinctive steam generation structure, which has various applications such as in the treatment of organic waste and hydrogen production for fuel cells in future vehicles. The operational features of the water plasma torch and water phase change process in the discharge chamber are investigated based on the temporal evolution of the voltage and current. The optical emission spectrum measurement shows that the water molecule in the plasma is decomposed into 14, OH and O radicals. As the electrodes do not require water-cooling, the thermal efficiency of the torch is very high, which is confirmed by analytical calculation and experimental measurement.