Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was...Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52%to 12.51%of the energy is utilized for rock breaking,while a significant 57.26%to 78.10%is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.展开更多
出版物的结构化处理是语义出版发展的基础。图书交换标签集(Book Interchange Tag Suite,BITS)是一套面向科技类图书的结构化表示模型。本文通过分析BITS模型的元素和结构,比较BITS与期刊标签集JATS以及电子书标准Docbook和DITA的异同,...出版物的结构化处理是语义出版发展的基础。图书交换标签集(Book Interchange Tag Suite,BITS)是一套面向科技类图书的结构化表示模型。本文通过分析BITS模型的元素和结构,比较BITS与期刊标签集JATS以及电子书标准Docbook和DITA的异同,并结合中文科技类图书的特点,以探讨BITS对中文图书的适用性和改进方向。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
本文提出一种多协议,可变位宽发射机系统,最高数据位宽40 bits,最高数据速率10.312 5 Gbps.整个系统由归一化数据位宽(Normalization of Data Width,NMDW)变换电路,40:1合路器(MUX),时钟分布电路及3抽头前馈均衡器(Feed-Forward-Equaliz...本文提出一种多协议,可变位宽发射机系统,最高数据位宽40 bits,最高数据速率10.312 5 Gbps.整个系统由归一化数据位宽(Normalization of Data Width,NMDW)变换电路,40:1合路器(MUX),时钟分布电路及3抽头前馈均衡器(Feed-Forward-Equalizer,FFE)组成,文章中提出了改进的40:1 MUX电路结构.本文采用SMIC 40 nm CMOS工艺,电源电压1.1 V.发射机(Transmitter,TX)整体功耗34mW@10.3125 Gbps,信道前差分输出眼图最大幅度大于800 mV.同时,本发射机支持4种不同协议,7种不同数据速率,9种工作状态,工作温度范围-45℃~125℃.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
随着计算机软硬件技术及超大规模集成电路技术的发展,电子设计自动化(EDA)逐渐取代了传统的电子设计方法,而成为现代电子设计的基本手段。仿真是EDA技术的典型特征,从一个既定的设计任务(16bits比较器)开始,从设计构思、在EDA仿真软件(M...随着计算机软硬件技术及超大规模集成电路技术的发展,电子设计自动化(EDA)逐渐取代了传统的电子设计方法,而成为现代电子设计的基本手段。仿真是EDA技术的典型特征,从一个既定的设计任务(16bits比较器)开始,从设计构思、在EDA仿真软件(Modelsim SE 5．6)平台上编写VHDL仿真软件、进行仿真测试等方面全面地介绍了进行系统计算机仿真的全过程。展开更多
基金Supported by Major Instrument Project of National Natural Science Foundation of China(52327803)Major Project of National Natural Science Foundation of China(52192622).
文摘Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52%to 12.51%of the energy is utilized for rock breaking,while a significant 57.26%to 78.10%is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.
文摘出版物的结构化处理是语义出版发展的基础。图书交换标签集(Book Interchange Tag Suite,BITS)是一套面向科技类图书的结构化表示模型。本文通过分析BITS模型的元素和结构,比较BITS与期刊标签集JATS以及电子书标准Docbook和DITA的异同,并结合中文科技类图书的特点,以探讨BITS对中文图书的适用性和改进方向。
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.
文摘随着计算机软硬件技术及超大规模集成电路技术的发展,电子设计自动化(EDA)逐渐取代了传统的电子设计方法,而成为现代电子设计的基本手段。仿真是EDA技术的典型特征,从一个既定的设计任务(16bits比较器)开始,从设计构思、在EDA仿真软件(Modelsim SE 5．6)平台上编写VHDL仿真软件、进行仿真测试等方面全面地介绍了进行系统计算机仿真的全过程。
