金属钼阴极发射特性的实验研究

在 1.2× 10 - 6 Pa的真空下 ,对多晶钼尖端阴极的热发射特性进行了实验研究 ,在工作温度 1.8～ 2 .2×10 3K ,亮度可达 10 4 A/cm2 ·sr .实验表明 ,用多晶钼代替单晶钼 ,同样可保证热发射特性的要求     

Fe、Ir掺杂单层MoS2的构型及电子结构的第一性原理研究

采用密度泛函理论方法对MoS2完整表面、吸附式掺杂和替换掺杂缺陷MoS2表面(Fe-MoS2、Ir-MoS2)的构型、电子结构进行了研究.结果表明:通过比较Fe、Ir原子吸附的吸附能,发现Ir比Fe在表面的吸附性更强,且在Mo原子的上方吸附最强,电子态密度分析说明了在Z方向上,Mo原子的4dyz、4dz2、4dxz轨道...     

溶液除湿辅助的蒸发过冷式流态冰制取方法

针对目前过冷水制取流态冰的方法常会碰到冰堵并且极度依赖电能的问题,提出了一种新的流态冰制取方法.新方法主要包括2个部分：蒸发式过冷过程和溶液除湿过程.对蒸发式过冷过程进行了理论研究,通过影响因子的引入改进了经典的扩散-控制模型;同时,对蒸发式过冷过程进行了实验研究,用粒子分析仪测量水滴的粒径与速度,用红外热像仪测量蒸发过冷过程的温度场.研究结果表明：改进的理论模型所得出的结果与实验结果吻合得很好.另外,通过与传统过冷水制取流态冰方法的比较发现,新方法可以回收利用自身排出的废热,降低了对电能的依赖,提高了制流态冰的效率,从而使系统的整体性能得到改善.     

焊接接头局部腐蚀行为表征的综合实验设计

依托现有的教师科研项目,设计了研究焊接接头多尺度腐蚀行为的综合性实验。该实验针对焊接接头这一非均匀结构的局部腐蚀问题,以微电极阵列为纽带,联用三种电化学测试方法,从三个不同尺度获取电化学信息,并进而对局部腐蚀过程进行准确解析。经典电化学测试结果表明,X80钢焊接接头的各组成部分若孤立存在,在CO₂饱和的3%NaCl溶液环境中的腐蚀电流密度为WM相似文献   

4Cr14Ni14W2Mo的相图计算及曲线分析

在分析典型的4Cr14Ni14W2Mo耐热钢的成分基础上,通过采用Thermo-Calc软件作为热力学计算工具,对奥氏体热强钢4Cr14Ni14W2Mo的伪二元平衡相图的转变过程进行了理论计算,对该实验钢种的相组成与温度之间的关系进行了定量分析,为实际的生产起到了一定理论的指导作用。     

高钨含量钽合金氩弧焊接工艺研究

采用质量百分比为12%的Ta-12W合金板材进行对接自熔氩弧焊和加钛焊料氩弧焊实验,观察了焊缝区的金相组织,分析了焊缝区的成分,并测试了焊接强度.实验结果表明：Ta-12W合金板材采用氩弧焊焊缝强度不高,拉伸断裂均发生在热影响区;加钛焊料氩弧焊接Ta-12W合金板材并未焊合,且焊缝处的成分扩散很不均匀;Ta-12W合金板材采用对接自熔氩弧焊方式优于加钛焊料氩弧焊方式.     

单原子催化剂Ir1/MoS2表面上NH3吸附理论研究

采用密度泛函理论与周期性平板模型相结合的方法,对单原子催化剂Ir在MoS2表面的fcc、hcp两个吸附位和NH3在单原子催化剂Ir1/MoS2上的四个吸附位的6种吸附模型进行了构型优化和能量计算,得到了Ir原子最稳定的吸附位以及NH3的优势吸附位;并对最佳吸附位进行了电荷密度差和态密度分析.结果表明:Ir1/MoS2体...     

磁控法测定热发射电子速率分布实验的完善与优化

该文通过求解极坐标系下电子在径向电场和轴向磁场中的运动方程,建立了引入阳极电压条件下热电子初速度与磁控管中电磁场强度之间的关系,并提出一种以归一化阳极电流与励磁电流之间的关系验证热发射电子速率满足麦克斯韦分布的方法.实验结果定性证明了上述方法的可行性,同时表明阳极电压的引入可以有效抑制空间电荷.为了得到更精确的热发射电...     

基于PF-LBM背景速度场对单晶核凝固生长的影响（英文）

在自然环境和工业系统中为了促进/抑制冰的形成,采用相场-粒子玻尔兹曼方法模拟了冰单晶核的生长演化过程,并分析背景流场条件对单晶核晶枝生长的影响.结果表明：背景流场使枝晶生长呈现不对称形状,即迎流侧的单晶核晶枝远比背流侧晶枝发达;迎流侧晶枝顶端生长速率远大于背流侧的枝晶生长速率,上游侧的晶枝尖端半径大于背流侧的晶枝尖端半径;在有背景流场条件下,单晶核的固相比大于无背景流场.背景流场的流速越高,迎流侧枝晶越发达,枝晶生长速度越快,枝晶尖端生长速度也越快.背流侧的流场流速较低,过冷度低于迎流侧,抑制了凝固过程,生长速度较慢,枝晶生长受到抑制.     

氧化锡纳米线在场致发射显示器中的应用研究

采用改进的热蒸发法制备了大量的一维氧化锡纳米线,利用丝网印刷工艺将制备的氧化锡纳米线印刷在玻璃基板银电极上作为场发射阴极材料,研究了阴极的场致发射特性,实现了原型显示器件的均匀点亮,实验结果表明,该方法制备的氧化锡纳米线作为阴极材料具有低的阈值电场(6.67 V/μm)、高的发射电流密度(205μA/cm2)和好的场发射稳定性(发射电流涨落幅度在10%以内).     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.