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基于颗粒流GBM模型的花岗岩声发射相对平静期特征研究 被引量:6
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作者 赵奎 刘永光 +2 位作者 曾鹏 伍文凯 王金鉴 《金属矿山》 CAS 北大核心 2021年第9期27-36,共10页
为了研究不同晶体粒径大小对花岗岩声发射相对平静期的影响,基于颗粒流软件PFC2D构建花岗岩等效晶体模型GBM(Grain-based model,GBM)数值计算模型,通过室内试验结果对细观参数进行标定,模拟花岗岩试件单轴压缩声发射试验。分析了不同晶... 为了研究不同晶体粒径大小对花岗岩声发射相对平静期的影响,基于颗粒流软件PFC2D构建花岗岩等效晶体模型GBM(Grain-based model,GBM)数值计算模型,通过室内试验结果对细观参数进行标定,模拟花岗岩试件单轴压缩声发射试验。分析了不同晶体粒径大小对试件应力—应变、峰值强度的影响规律,着重分析了试件破坏过程中裂纹、声发射时空演化特征及相对平静期的产生机理。同时,研究了试件声发射相对平静期前后能量变化特征及其与晶体粒径大小的关系。研究结果表明:(1)随着晶体粒径增大,试件的单轴抗压强度增大。试件破坏形式主要呈"X"型剪切和"V"型柱状劈裂。同时不同晶体粒径大小试件的微裂纹均以张拉破坏为主,且首先产生沿晶微裂纹,在声发射相对平静期起始点开始产生穿晶微裂纹。(2)试件在单轴压缩过程中,声发射在应力峰值前均出现不同程度的相对平静期,且在相对平静期前声发射产生的位置为沿晶体边界;在相对平静期起始点之后,将同时产生位于晶体内部和晶体边界的声发射。(3)声发射相对平静期内滑移能和阻尼能的变化量随着晶体粒径的增大逐渐减小。其中,由于在声发射相对平静期内声发射明显减少,岩石内部活动处于相对平静状态,因此释放的动能减少。 展开更多
关键词 声发射 等效晶体 颗粒流 相对平静期 花岗岩
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Non-Destructive Parameters Extraction for a Novel IGBT SPICE Model and Verified with Measurements 被引量:4
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作者 袁寿财 朱长纯 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2003年第7期702-706,共5页
An IGBT subcircuit model is proposed and optimized,which is fully SPICE compatible.Based on analytical equations describing the semiconductor device physics,the model parameters are extracted accurately from the measu... An IGBT subcircuit model is proposed and optimized,which is fully SPICE compatible.Based on analytical equations describing the semiconductor device physics,the model parameters are extracted accurately from the measured data without device destruction.The IGBT n - layer conductivity modulated resistor is effectively modeled as a voltage controlled resistor.The proposed model can be used to accurately predict the IGBT output I-V characteristics and low current gain etc.The simulation results are verified by the comparison with measurements and found to be in good agreement with them.The error in average is within 8%,which is better than the results of semi-mathematical models reported previously. 展开更多
关键词 IGBT subcircuit simulation SPICE-model parameter-extraction
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阻容耦合放大器低频特性的研究 被引量:1
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作者 麻幼学 《肇庆学院学报》 2003年第5期7-11,共5页
运用节点法和晶体管参数等效电路,对单级阻容耦合晶体管共射极放大器的低频特性进行了分析,说明教材中提供的分析方法不能用于讨论放大器的低频特性.
关键词 阻容耦合放大器 低频特性 节点法 晶体管参数等效电路 下限截止频率
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Is quantum capacitance in graphene a potential hurdle for device scaling?
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作者 Jaeho Lee Hyun-Jong Chung +6 位作者 David H. Seo Jaehong Lee Hyungcheol Shin Sunae Seo Seongjun Park Sungwoo Hwang Kinam Kim 《Nano Research》 SCIE EI CAS CSCD 2014年第4期453-461,共9页
Transistor size is constantly being reduced to improve performance as well as power consumption. For the channel length to be reduced, the corresponding gate dielectric thickness should also be reduced. Unfortunately,... Transistor size is constantly being reduced to improve performance as well as power consumption. For the channel length to be reduced, the corresponding gate dielectric thickness should also be reduced. Unfortunately, graphene devices are more complicated due to an extra capacitance called quantum capacitance (CQ) which limits the effective gate dielectric reduction. In this work, we analyzed the effect of CQ on device-scaling issues by extracting it from scaling of the channel length of devices. In contrast to previous reports for metal-insulator- metal structures, a practical device structure was used in conjunction with direct radio-frequency field-effect transistor measurements to describe the graphene channels. In order to precisely extract device parameters, we reassessed the equivalent circuit, and concluded that the on-state model should in fact be used. By careful consideration of the underlap region, our device modeling was shown to be in good agreement with the experimental data. CQ contributions to equivalent oxide thickness were analyzed in detail for varying impurity concentrations in graphene. Finally, we were able to demonstrate that despite contributions from CQ, graphene's high mobility and low-voltage operation allows for ~raphene channels suitable for next generation transistors. 展开更多
关键词 GRAPHENE equivalent circuit quantum capacitance intrinsic delay
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