Low cost and miniaturized rotary encoders are important in automatic and precise production. Presented here is a code called Single Track Cyclic Gray Code (STCGC) that is an image etched on a single circular track of ...Low cost and miniaturized rotary encoders are important in automatic and precise production. Presented here is a code called Single Track Cyclic Gray Code (STCGC) that is an image etched on a single circular track of a rotary encoder disk read by a group of even spread reading heads to provide a unique codeword for every angular position and features such that every two adjacent words differ in exactly one component, thus avoiding coarse error. The existing construction or combination methods are helpful but not sufficient in determining the period of the STCGC of large word length and the theoretical approach needs further development to extend the word length. Three principles, such as the seed combination, short code removal and ergodicity examination were put forward that suffice determination of the optimal period for such absolute rotary encoders using STCGC with even spread heads. The optimal periods of STCGC in 3 through 29 bit length were determined and listed.展开更多
深部煤层处于高温高压环境,甲烷呈超临界态,实验获得过剩吸附量与实际的绝对吸附量存在较大偏差,二者之间的校正显得尤为重要。但目前校正系数中的吸附相密度大多采用了饱和液相密度或van der Waals密度这一定值,与甲烷吸附相密度随压...深部煤层处于高温高压环境,甲烷呈超临界态,实验获得过剩吸附量与实际的绝对吸附量存在较大偏差,二者之间的校正显得尤为重要。但目前校正系数中的吸附相密度大多采用了饱和液相密度或van der Waals密度这一定值,与甲烷吸附相密度随压力和温度变化的事实不符。本研究首先基于前人实验数据和理论分析建立了深部煤层中甲烷吸附相密度随温度和压力变化的数学模型;然后提出了吸附模型参数确定方法,优选出了考虑变吸附相密度的深部煤层气吸附解吸模型;最后进行了实例应用。研究表明,甲烷吸附相与游离相的密度差随压力先快速上升后缓慢上升并逐渐趋于一定值,随温度呈指数型渐进下降趋势;考虑变吸附相密度的深部煤层气吸附解吸模型,借助8个误差函数优选而来,可以准确表征深部煤层气吸附解吸特征;对于目标深部煤层气藏,Langmuir-Freundlich模型为最优的吸附解吸模型。研究成果可为深部煤层气藏类型划分、不同气体含量占比评价及排采制度优化确定提供理论基础。展开更多
基金Project(JX2004J0170) supported by the Foundation of Beijing Jiaotong University, China
文摘Low cost and miniaturized rotary encoders are important in automatic and precise production. Presented here is a code called Single Track Cyclic Gray Code (STCGC) that is an image etched on a single circular track of a rotary encoder disk read by a group of even spread reading heads to provide a unique codeword for every angular position and features such that every two adjacent words differ in exactly one component, thus avoiding coarse error. The existing construction or combination methods are helpful but not sufficient in determining the period of the STCGC of large word length and the theoretical approach needs further development to extend the word length. Three principles, such as the seed combination, short code removal and ergodicity examination were put forward that suffice determination of the optimal period for such absolute rotary encoders using STCGC with even spread heads. The optimal periods of STCGC in 3 through 29 bit length were determined and listed.
基金Supported by National High Technology Research and Development Program of China（863 Program）（2009AA04Z139） National Natural Science Foundation of China（60904011）+1 种基金 Natural Science Foundation of Zhejiang Province（Y1090834） Science Foundation of Zhejiang Sci-Tech University（ZSTU0803817-Y）
基金Supported by National Natural Science Foundation of China （60721062） and National High Technology Research and Development Program of China （863 Program） （2006AA04Z182）
文摘深部煤层处于高温高压环境,甲烷呈超临界态,实验获得过剩吸附量与实际的绝对吸附量存在较大偏差,二者之间的校正显得尤为重要。但目前校正系数中的吸附相密度大多采用了饱和液相密度或van der Waals密度这一定值,与甲烷吸附相密度随压力和温度变化的事实不符。本研究首先基于前人实验数据和理论分析建立了深部煤层中甲烷吸附相密度随温度和压力变化的数学模型;然后提出了吸附模型参数确定方法,优选出了考虑变吸附相密度的深部煤层气吸附解吸模型;最后进行了实例应用。研究表明,甲烷吸附相与游离相的密度差随压力先快速上升后缓慢上升并逐渐趋于一定值,随温度呈指数型渐进下降趋势;考虑变吸附相密度的深部煤层气吸附解吸模型,借助8个误差函数优选而来,可以准确表征深部煤层气吸附解吸特征;对于目标深部煤层气藏,Langmuir-Freundlich模型为最优的吸附解吸模型。研究成果可为深部煤层气藏类型划分、不同气体含量占比评价及排采制度优化确定提供理论基础。
