逐次逼近寄存器模数转换器(SAR ADC)在逐次逼近的过程中,电容的切换会使参考电压上出现参考纹波噪声,该噪声会影响比较器的判定,进而输出错误的比较结果。针对该问题,基于CMOS 0.5μm工艺,设计了一种具有纹波消除技术的10 bit SAR ADC...逐次逼近寄存器模数转换器(SAR ADC)在逐次逼近的过程中,电容的切换会使参考电压上出现参考纹波噪声,该噪声会影响比较器的判定,进而输出错误的比较结果。针对该问题,基于CMOS 0.5μm工艺,设计了一种具有纹波消除技术的10 bit SAR ADC。通过增加纹波至比较器输入端的额外路径,将参考纹波满摆幅输入至比较器中;同时设计了消除数模转换器(DAC)模块,对参考纹波进行采样和输入,通过反转纹波噪声的极性,消除参考纹波对ADC输出的影响。该设计将信噪比(SNR)提高到56.75 dB,将有效位数(ENOB)提升到9.14 bit,将积分非线性(INL)从-1~5 LSB降低到-0.2~0.3 LSB,将微分非线性(DNL)从-3~4 LSB降低到-0.5~0.5 LSB。展开更多
In most effective bits evaluation of waveform recorders, the prerequisite is that there is no signal source distortion, or the distortion can be neglected. But when the distortion can be neglected or how it affects th...In most effective bits evaluation of waveform recorders, the prerequisite is that there is no signal source distortion, or the distortion can be neglected. But when the distortion can be neglected or how it affects the evaluation when it can't be neglected it is not determined yet. In this paper, the influence of signal source distortion to the evaluation of the effective bits of waveform recorders is discussed, then, the correction method of the effective bits error caused by the distortion influence is given. Finally , the error limit of the effective bits is given and how to selecte the calibrator is introduced. In the end , some simulation results of the new method in test are described.展开更多
目的:分析EB病毒相关性噬血细胞综合征(EB virus-associated hemophagocytic syndrome,EBVAHS)患儿EB病毒潜伏膜蛋白1(latent membrane protein 1,LMP1)、辅助性T细胞1(helper T cell1,Th1)细胞因子的表达水平及其与疗效的关系。方法:...目的:分析EB病毒相关性噬血细胞综合征(EB virus-associated hemophagocytic syndrome,EBVAHS)患儿EB病毒潜伏膜蛋白1(latent membrane protein 1,LMP1)、辅助性T细胞1(helper T cell1,Th1)细胞因子的表达水平及其与疗效的关系。方法:抽取郑州大学附属儿童医院儿科2014年2月至2018年1月收治的116例EB病毒感染患儿为研究对象,分为单核细胞增多症(infect iousmononucleosis,IM)组与EBV-AHS组,其中IM 66例,EBV-AHS 50例。EBV-AHS组按照国际组织细胞协会推荐的HLH-2004方案给予治疗,于治疗4周后评定近期疗效。另选取同期体检的健康儿童30例作为对照组。对照组于体检时、IM组于确诊时、EBV-AHS组于治疗前、治疗后采血,检测血清LMP1抗体表达及Th1细胞因子水平。结果:与对照组相比,IM组和EBV-AHS组患儿确诊时血清LMP1抗体、白介素(IL)-2、干扰素(IFN)-γ及肿瘤坏死因子(TNF)-α水平显著增高,差异有统计学意义(P<0.05)。IM组和EBV-AHS组患儿血清LMP1抗体,IL-2,IFN-γ,TNF-α水平差异亦有统计学意义(P<0.05)。治疗后EBV-AHS组50例患儿中,疾病缓解者17例(34.00%),有效者22例(44.00%),余下11例(22.00%)疾病活动。疾病缓解者、有效者血清LMP1抗体,IL-2,IFN-γ,TNF-α水平明显较治疗前降低(P<0.05),而疾病活动者血清LMP1抗体,IL-2,IFN-γ,TNF-α水平较治疗前无明显改善(P>0.05);且疾病缓解者、有效者、疾病活动者血清LMP1抗体,IL-2,IFN-γ,TNF-α水平均依次升高,差异有统计学意义(P<0.05)。结论:EBV-AHS患儿血清LMP1抗体表达及Th1细胞因子水平较IM患儿及正常儿童显著升高,且其与疗效密切相关。展开更多
Radial drilling technology, of which the jet bit is the key device, is a research focus in the field of oil drilling and production. This paper establishes mechanical equations for jet bits and analyzes the hydroseal ...Radial drilling technology, of which the jet bit is the key device, is a research focus in the field of oil drilling and production. This paper establishes mechanical equations for jet bits and analyzes the hydroseal of backward jets in bottom holes. Meanwhile this paper establishes a mechanical equation for a high pressure hose and analyzes the axial force distribution. Laboratory experiments indicate that the flow rate, the angle between the backward nozzle axis and the jet bit axis, and the hole diameter are the major influencing factors; the generation of the pulling force is mainly due to the inlet pressure of the jet bit; the backward jets can significantly increase not only the pulling force but also the stability of jet bits. The pulling force would reach 8,376 N under experimental conditions, which can steadily pull the high-pressure hose forward.展开更多
文摘In most effective bits evaluation of waveform recorders, the prerequisite is that there is no signal source distortion, or the distortion can be neglected. But when the distortion can be neglected or how it affects the evaluation when it can't be neglected it is not determined yet. In this paper, the influence of signal source distortion to the evaluation of the effective bits of waveform recorders is discussed, then, the correction method of the effective bits error caused by the distortion influence is given. Finally , the error limit of the effective bits is given and how to selecte the calibrator is introduced. In the end , some simulation results of the new method in test are described.
基金supported by High-tech Research and Development Program of China (No. 2007AA09Z315)Doctoral Foundation of Ministry of Education of China (No. 20070425006)
文摘Radial drilling technology, of which the jet bit is the key device, is a research focus in the field of oil drilling and production. This paper establishes mechanical equations for jet bits and analyzes the hydroseal of backward jets in bottom holes. Meanwhile this paper establishes a mechanical equation for a high pressure hose and analyzes the axial force distribution. Laboratory experiments indicate that the flow rate, the angle between the backward nozzle axis and the jet bit axis, and the hole diameter are the major influencing factors; the generation of the pulling force is mainly due to the inlet pressure of the jet bit; the backward jets can significantly increase not only the pulling force but also the stability of jet bits. The pulling force would reach 8,376 N under experimental conditions, which can steadily pull the high-pressure hose forward.
