基于曲线拟合的信噪比估计方法研究

在无线通信系统中,信噪比作为衡量信道质量的重要参数,为许多自适应技术提供信道质量信息。由于周期平稳信号与高斯白噪声自相关函数的特性不同,用曲线拟合的方法,分离出自相关函数中的周期平稳信号和噪声的能量,从而计算出信噪比。最后仿真表明,该方法相对于其他方法具有较高的估计精度,并且计算复杂度较低。     

锅炉引风机振动原因分析及建议

引风机是锅炉的主要辅机．也是关键设备之一。引风机运行情况的好坏．直接关系到锅炉的长周期运行．而引风机的振动则是影响其运行的主要因素，克服和解决引风机的振动问题，将有助于锅炉的稳定运行。兰州石化化肥厂动力车间煤锅炉肩负着给大化肥装置提供动力蒸汽的重任．加上冬季蒸汽紧张．一旦锅炉出现故障，将严重制约生产任务的完成。     

4H-SiC埋沟MOSFET的研制

研制了4H-SiC热氧化生长氧化层埋沟nMOSFET.用室温下N离子注入的方法形成埋沟区和源漏区,然后在1600℃进行激活退火.离子注入所得到的埋沟区深度大约为0.2μm.从转移特性提取出来的峰值场效应迁移率约为18.1cm2/(V·s).造成低场效应迁移率的主要因素可能是粗糙的器件表面(器件表面布满密密麻麻的小坑).3μm和5μm器件的阈值电压分别为1.73V和1.72V.3μm器件饱和跨导约为102μS( V G=20V, V D=10V).     

HEMT的静态和小信号解析模型

本文在提出一个新的二段非线性２ＤＥＧ模型的基础上，建立了ＨＥＭＴ的静态和高频解析模型．对交流波动方程采用Ｂｅｓｓｅｌ函数法得到精确解．由直流特性和表征高频特性的参数和实验数据的比较表明，本模型与实验符合得相当好．     

750kV格构式变电构架节点板厚度优化试验研究及仿真分析

对采用不同厚度节点板的750kV格构式变电构架格构柱KT形节点进行了足尺试验及有限元仿真分析,考察了其在设计荷载和1.5倍设计荷载作用下的受力及变形情况。结果表明,节点板厚度减小后,设计荷载作用下其仍处于弹性工作状态,1.5倍设计荷载作用下其仍然安全,可为节点板设计提供参考依据。     

Fabrication and characteristics of a 4H-SiC junction barrier Schottky diode

4H-SiC junction barrier Schottky(JBS)diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently,and the other is processed by depositing a Schottky metal multi-layer on the whole anode.The reverse performances are compared to find the influences of these factors.The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage,and with independent P-type ohmic contact manufacturing,the reverse performance of 4H-SiC JBS diodes can be improved effectively. Furthermore,the P-type ohmic contact is studied in this work.     

用安全文化的力量提升安全生产管理水平的探索

本文就以安全文化建设提升企业安全管理水平做了一些初步探索。     

不同氧化退火工艺下SiO2/SiC界面特性研究

The effect of the different re-oxidation annealing （ROA） processes on the SiO2/SiC interface charac- teristics has been investigated. With different annealing processes, the flat band voltage, effective dielectric charge density and interface trap density are obtained from the capacitance-voltage curves. It is found that the lowest interface trap density is obtained by the wet-oxidation annealing process at 1050 ℃ for 30 min, while a large num- ber of effective dielectric charges are generated. The components at the SiO2/SiC interface are analyzed by X-ray photoelectron spectroscopy （XPS） testing. It is found that the effective dielectric charges are generated due to the existence of the C and H atoms in the wet-oxidation annealing process.