用精密锁相放大器剖析稳压二极管的噪声特性

运用精密锁相放大器对一些稳压二极管的噪声特性进行了全面测试,解释了实际使用中发现噪声与生产厂提供的噪声指标不符的事实,为用户正确使用稳压二极管提供了依据。     

ACCESS数据库和SQL_Server数据库的应用比较

随着网络应用不断发展,系统性能已越来越引起决策者的重视,数据库性能问题一直是决策者及技术人员共同关注的焦点。一般情况下,我们只接触到ACCESS数据库和SQL_Server数据库,下面对它们做个简单的介绍,以便大家对数据库的应用有个基本的了解。     

Fabrication and investigation of ferroelectric memristors with various synaptic plasticities

In the post-Moore era, neuromorphic computing has been mainly focused on breaking the von Neumann bottlenecks. Memristors have been proposed as a key part of neuromorphic computing architectures, and can be used to emulate the synaptic plasticities of the human brain. Ferroelectric memristors represent a breakthrough for memristive devices on account of their reliable nonvolatile storage, low write/read latency and tunable conductive states. However, among the reported ferroelectric memristors, the mechanisms of resistive switching are still under debate. In addition, there needs to be more research on emulation of the brain synapses using ferroelectric memristors. Herein, Cu/PbZr_0.52Ti_0.48O₃ (PZT)/Pt ferroelectric memristors have been fabricated. The devices are able to realize the transformation from threshold switching behavior to resistive switching behavior. The synaptic plasticities, including excitatory post-synaptic current, paired-pulse facilitation, paired-pulse depression and spike time-dependent plasticity, have been mimicked by the PZT devices. Furthermore, the mechanisms of PZT devices have been investigated by first-principles calculations based on the interface barrier and conductive filament models. This work may contribute to the application of ferroelectric memristors in neuromorphic computing systems.     

国家信息下策的背景研究范畴和建设策略

本文从国家信息政策的背景出发，分析了国家信息政策陆续颁布的原因及其现状，目前，国家信息政策的研究范畴极为广泛，笔者结合我国信息产业发展的具体情况，指 国信息政策应研究的重点，进而提出了我国信息政策的建设策略。     

使用SiNx原位淀积方法生长的GaN外延膜中的应力研究

采用低压MOCVD系统,在生长过程中使用SiNx原位淀积的方法产生纳米掩模,并在纳米掩模上进行选区生长和侧向外延制备了GaN外延薄膜.使用拉曼光谱和光荧光的手段对GaN外延膜中的残余应力进行了研究.研究发现,用SiNx原位淀积出纳米掩模后,GaN生长将由二维向三维转变,直到完全合并为止.利用拉曼光谱和光荧光谱分别研究了薄膜中的残余应力,两者符合得很好;这种方法生长出的GaN薄膜的应力分布较传统的侧向外延更加均匀;并且从中发现随着生长过程中SiNx原位淀积时间的增加,生长在其上的GaN外延膜中的残余应力减小.这是因为,随着SiNx原位淀积时间的增加,SiNx纳米掩模的覆盖度也增大.因此侧向外延区的比例增大,残余应力随之减小.     

紫甘薯营养成分分析及休闲食品开发

以紫甘薯粉为原料分析了紫甘薯粉的营养成分,开发了紫甘薯馅饼休闲食品,并确定了紫甘薯馅饼的配方,为75％紫甘薯粉和25％糯米粉。同时研究了加热方式和包装方式对紫甘薯速冻馅饼的影响。     

基于位移检测的机器人碰撞传感器研究与设计

为了避免机器人末端执行器在工作过程中与周围设备人员发生碰撞,造成设备损坏或者人员伤害,设计一款基于位移检测的机器人碰撞传感器。在对传感器连杆进行力学分析和建立平衡方程式的基础上,根据其碰撞过程中传感器活动部件的运动轨迹,导出了末端执行器空间碰撞力模型及相应的传感器碰撞力阈值计算公式,完成了传感器的设计、动力学仿真、制作装配和静态测试。实验结果表明,该传感器对末端执行器具有碰撞检测和缓冲保护功能,在机器人安全防护和人机协作方面具有一定的应用价值。     

Electroluminescence of an n-ZnO/p-GaN Heterojunction under Forward and Reverse Biases

Electroluminescent characteristics of n-ZnO/p-GaN heterojunctions under forward and reverse biases are studied. Emissions at 389nm and 57Ohm are observed under forward bias. An unusual emission at 390ram appears under reverse bias, and is attributed to the recombination in the p-GaN side of the heterojunction. The yellow emission peaked at 57Ohm is suppressed under reverse bias. The light intensity exponentially depends on the reverse current. The emission under reverse bias is correlated to tunnelling carrier transport in the heterostructure. Our results also support that the well-known yellow band of GaN comes from the transitions between some near-conduction-band-edge states and deep localized acceptor states.     

Passively Q-Switched Nd:YVO_4 Laser Using a Gold Nanotriangle Saturable Absorber

A passively Q-switched Nd:YVO_4 laser at 1064 nm is demonstrated based on a gold nanotriangle saturable absorber(GNT SA).Under a pump power of 3.82 W,the maximum average output power of 218mW is achieved,corresponding to a slope efficiency of 12.9%.The minimum pulse width is 165ns and the maximum pulse repetition rate is 300kHz at the pump power of 3.48 W.Our results prove that the GNT SA is a promising saturable absorber for near-infrared lasers.     

关于数据挖掘原理与算法的浅析

数据挖掘又称为KDD,广义上讲,数据挖掘是一个从大量的数据中提取人们感兴趣的模式的过程,是数据库中知识发现过程的一个基本步骤。本文主要通过论述数据挖掘的原理与相关算法进行研究与分析,已达到数据挖掘在生活中更好的实际应用的目的。