Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure on silicon wafer manufacturers to develop cost-effective manufacturing process...Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure on silicon wafer manufacturers to develop cost-effective manufacturing processes. A critical issue in wafer production is the waviness induced by wire sawing. If this waviness is not removed, it will affect wafer flatness and semiconductor performance. In practice, both lapping and grinding have been used to flatten wire-sawn wafers. Although grinding is not as effective as lapping in removing waviness, it has many other advantages over lapping (such as higher throughput, fully automatic, and more benign to environment) and has great potential to reduce manufacturing cost of silicon wafers. This paper presents a finite element analysis (FEA) study on grinding and lapping of wire-sawn silicon wafers. An FEA model is first developed to simulate the waviness deformation of wire-sawn wafers in grinding and lapping processes. It is then used to explain how the waviness is removed or reduced by lapping and grinding and why the effectiveness of grinding in removing waviness is different from that of lapping. Furthermore, the model is used to study the effects of various parameters including active-grinding-zone orientation, grinding force, waviness wavelength, and waviness height on the reduction and elimination of waviness. Finally, the results of pilot experiments to verify the model are discussed.展开更多
利用LAPS(local analysis and prediction system)同化系统融合多种观测资料,对2010年8月25日发生在上海的一次强对流天气过程进行中尺度分析。结果表明,这次强对流天气主要是由中、低空中尺度辐合系统直接触发形成的。强对流形成阶段,...利用LAPS(local analysis and prediction system)同化系统融合多种观测资料,对2010年8月25日发生在上海的一次强对流天气过程进行中尺度分析。结果表明,这次强对流天气主要是由中、低空中尺度辐合系统直接触发形成的。强对流形成阶段,地面有分散辐合形成并逐渐加强,成为触发中尺度垂直环流的主要机制,垂直结构上出现低层辐合高层辐散的有利配置,风暴中心附近出现明显的上升气流区,中高层相对湿度显著增加。成熟阶段,强对流云体中心附近的对流层底层开始出现下沉气流,上升气流在其拖曳作用下明显倾斜。衰减阶段,下沉气流加强使中尺度环流动力结构和水汽供应受到破坏,垂直结构上转为底层辐散高层辐合。因此,与天气尺度分析相比,基于LAPS的中尺度分析能更深刻地揭示中小尺度系统的三维结构和时空演变特征。展开更多
本文首先基于地面自动站、探空、雷达和卫星资料,开展局地分析预报系统(Local Analysis and Prediction System,LAPS)上海本地化研究,并结合2010—2014年夏季6个局地对流天气个例对其性能进行检验评估。结果表明:雷达径向风资料对LAPS...本文首先基于地面自动站、探空、雷达和卫星资料,开展局地分析预报系统(Local Analysis and Prediction System,LAPS)上海本地化研究,并结合2010—2014年夏季6个局地对流天气个例对其性能进行检验评估。结果表明:雷达径向风资料对LAPS风速分析影响较大,使分析场风速廓线与探空廓线的均方根误差缩小约7.66%;风云卫星资料能够改善LAPS温度和相对湿度,使分析场温度、相对湿度廓线与探空廓线的均方根误差分别缩小约9.09%和14.01%;探空气球飘移对本文LAPS分析场检验影响不明显。进一步将LAPS分析场用于2011年8月13日、2014年8月4日两次局地对流个例分析表明:LAPS高时空分辨率的分析场能够反映中小尺度天气系统的时空变化,在天气尺度背景并不十分有利于对流生成的情况下,热岛、海陆风环流的形成和持续对上海夏季局地对流天气的发生和发展起到关键作用。展开更多
针对Local Analysis and Prediction System(LAPS)融合我国新一代多普勒雷达基数据时产生的资料空白问题,设计采用最大值和距离指数权重拼图方法来改进LAPS原有的最近邻居法,并且尝试通过最小二乘法来模拟静锥区的反射率值。试验结果表...针对Local Analysis and Prediction System(LAPS)融合我国新一代多普勒雷达基数据时产生的资料空白问题,设计采用最大值和距离指数权重拼图方法来改进LAPS原有的最近邻居法,并且尝试通过最小二乘法来模拟静锥区的反射率值。试验结果表明,最大值法和距离指数权重法能够充分发挥多部雷达观测反射率的效能,有效地改善高仰角之间的资料空白现象,对静锥区也有一些的填补,特别是在对流层中层。最小二乘法拟合静锥区反射率试验取得了一定的效果,能够较好地拟合静锥区周围观测资料比较多的情况。该研究改善了LAPS同化国产多普勒雷达资料的能力,提高了多部雷达观测的利用效能,将会对LAPS分析产生积极的影响。展开更多
LAPS(Local Analysis and Prediction System)采用物理初值化与三维变分约束相结合的方法,通过融合多源观测资料,发挥各种资料的优势,分析得到较为客观的三维云场,并可改善数值模式初始场。将FY-2E卫星可见光反照率和红外亮温资料引入LA...LAPS(Local Analysis and Prediction System)采用物理初值化与三维变分约束相结合的方法,通过融合多源观测资料,发挥各种资料的优势,分析得到较为客观的三维云场,并可改善数值模式初始场。将FY-2E卫星可见光反照率和红外亮温资料引入LAPS,针对2014年6月登陆我国的台风"海贝思",设计不同水平分辨率的同化试验,研究台风三维云结构和初始场的改善情况。结果表明:1)LAPS云分析中引入卫星可见光反照率资料之后,总云量有显著的调整,能够较清晰地分辨出台风眼区、云墙和螺旋云带,卫星红外亮温资料在云顶高度的调整中发挥了重要作用,而且高分辨率的云分析结果有助于更好地分析出台风结构和强对流区域。2)LAPS物理初值化技术将卫星资料中的云结构和微物理信息添加到初始场中,一定程度上调整了数值模式初始场中垂直速度、云水、云冰和水汽场等变量的分布,提高了模式初值质量,对模拟和预报台风系统将会产生一定的影响。展开更多
<正>A full automatic device to detect heavy metal Hg,Fe,Cr elements based on thin-film sensitive materials prepared on surface of light-addressable potentiometric sensors (LAPS) by means of pulsed laser depositi...<正>A full automatic device to detect heavy metal Hg,Fe,Cr elements based on thin-film sensitive materials prepared on surface of light-addressable potentiometric sensors (LAPS) by means of pulsed laser deposition PLD) technique is developed. High-purity chemical compound AgI:Ag_2S:HgI synthesized were used as target of PLD,thin film sensitive to Hg~ (2+) ion was prepared on the surface of LAPS.All-solide-state chalcogenide glass ion-selective electrodes ISE) ,Fe-ISE and Cr-ISE,were also used as targets of PLD,and thin-film sensors on different LAPS sensitive to Fe~ (3+) and Cr~ (6+) ions were prepared.The heavy metal analysis device with characteristics of collect sample in-site,real-time determination,communication and multifunction software were designed.Hardware design of the device mainly includes control and measurement aspects.The detected limits of Hg,Fe,Cr ions are 3.44×10~ (-7) mol/L,6.31×10~ (-6) mol/L and 2.09×10~ (-7) mol/L,respectively.展开更多
文摘Silicon wafers are the most widely used substrates for semiconductors. The falling price of silicon wafers has created tremendous pressure on silicon wafer manufacturers to develop cost-effective manufacturing processes. A critical issue in wafer production is the waviness induced by wire sawing. If this waviness is not removed, it will affect wafer flatness and semiconductor performance. In practice, both lapping and grinding have been used to flatten wire-sawn wafers. Although grinding is not as effective as lapping in removing waviness, it has many other advantages over lapping (such as higher throughput, fully automatic, and more benign to environment) and has great potential to reduce manufacturing cost of silicon wafers. This paper presents a finite element analysis (FEA) study on grinding and lapping of wire-sawn silicon wafers. An FEA model is first developed to simulate the waviness deformation of wire-sawn wafers in grinding and lapping processes. It is then used to explain how the waviness is removed or reduced by lapping and grinding and why the effectiveness of grinding in removing waviness is different from that of lapping. Furthermore, the model is used to study the effects of various parameters including active-grinding-zone orientation, grinding force, waviness wavelength, and waviness height on the reduction and elimination of waviness. Finally, the results of pilot experiments to verify the model are discussed.
文摘利用LAPS(local analysis and prediction system)同化系统融合多种观测资料,对2010年8月25日发生在上海的一次强对流天气过程进行中尺度分析。结果表明,这次强对流天气主要是由中、低空中尺度辐合系统直接触发形成的。强对流形成阶段,地面有分散辐合形成并逐渐加强,成为触发中尺度垂直环流的主要机制,垂直结构上出现低层辐合高层辐散的有利配置,风暴中心附近出现明显的上升气流区,中高层相对湿度显著增加。成熟阶段,强对流云体中心附近的对流层底层开始出现下沉气流,上升气流在其拖曳作用下明显倾斜。衰减阶段,下沉气流加强使中尺度环流动力结构和水汽供应受到破坏,垂直结构上转为底层辐散高层辐合。因此,与天气尺度分析相比,基于LAPS的中尺度分析能更深刻地揭示中小尺度系统的三维结构和时空演变特征。
文摘本文首先基于地面自动站、探空、雷达和卫星资料,开展局地分析预报系统(Local Analysis and Prediction System,LAPS)上海本地化研究,并结合2010—2014年夏季6个局地对流天气个例对其性能进行检验评估。结果表明:雷达径向风资料对LAPS风速分析影响较大,使分析场风速廓线与探空廓线的均方根误差缩小约7.66%;风云卫星资料能够改善LAPS温度和相对湿度,使分析场温度、相对湿度廓线与探空廓线的均方根误差分别缩小约9.09%和14.01%;探空气球飘移对本文LAPS分析场检验影响不明显。进一步将LAPS分析场用于2011年8月13日、2014年8月4日两次局地对流个例分析表明:LAPS高时空分辨率的分析场能够反映中小尺度天气系统的时空变化,在天气尺度背景并不十分有利于对流生成的情况下,热岛、海陆风环流的形成和持续对上海夏季局地对流天气的发生和发展起到关键作用。
文摘针对Local Analysis and Prediction System(LAPS)融合我国新一代多普勒雷达基数据时产生的资料空白问题,设计采用最大值和距离指数权重拼图方法来改进LAPS原有的最近邻居法,并且尝试通过最小二乘法来模拟静锥区的反射率值。试验结果表明,最大值法和距离指数权重法能够充分发挥多部雷达观测反射率的效能,有效地改善高仰角之间的资料空白现象,对静锥区也有一些的填补,特别是在对流层中层。最小二乘法拟合静锥区反射率试验取得了一定的效果,能够较好地拟合静锥区周围观测资料比较多的情况。该研究改善了LAPS同化国产多普勒雷达资料的能力,提高了多部雷达观测的利用效能,将会对LAPS分析产生积极的影响。
文摘LAPS(Local Analysis and Prediction System)采用物理初值化与三维变分约束相结合的方法,通过融合多源观测资料,发挥各种资料的优势,分析得到较为客观的三维云场,并可改善数值模式初始场。将FY-2E卫星可见光反照率和红外亮温资料引入LAPS,针对2014年6月登陆我国的台风"海贝思",设计不同水平分辨率的同化试验,研究台风三维云结构和初始场的改善情况。结果表明:1)LAPS云分析中引入卫星可见光反照率资料之后,总云量有显著的调整,能够较清晰地分辨出台风眼区、云墙和螺旋云带,卫星红外亮温资料在云顶高度的调整中发挥了重要作用,而且高分辨率的云分析结果有助于更好地分析出台风结构和强对流区域。2)LAPS物理初值化技术将卫星资料中的云结构和微物理信息添加到初始场中,一定程度上调整了数值模式初始场中垂直速度、云水、云冰和水汽场等变量的分布,提高了模式初值质量,对模拟和预报台风系统将会产生一定的影响。
文摘<正>A full automatic device to detect heavy metal Hg,Fe,Cr elements based on thin-film sensitive materials prepared on surface of light-addressable potentiometric sensors (LAPS) by means of pulsed laser deposition PLD) technique is developed. High-purity chemical compound AgI:Ag_2S:HgI synthesized were used as target of PLD,thin film sensitive to Hg~ (2+) ion was prepared on the surface of LAPS.All-solide-state chalcogenide glass ion-selective electrodes ISE) ,Fe-ISE and Cr-ISE,were also used as targets of PLD,and thin-film sensors on different LAPS sensitive to Fe~ (3+) and Cr~ (6+) ions were prepared.The heavy metal analysis device with characteristics of collect sample in-site,real-time determination,communication and multifunction software were designed.Hardware design of the device mainly includes control and measurement aspects.The detected limits of Hg,Fe,Cr ions are 3.44×10~ (-7) mol/L,6.31×10~ (-6) mol/L and 2.09×10~ (-7) mol/L,respectively.
