Elements can be classified into metals,nonmetals,or metalloids based on their chemical and physical properties.Precious metals are rare and expensive.There are ten known precious metals,three of which are of interest ...Elements can be classified into metals,nonmetals,or metalloids based on their chemical and physical properties.Precious metals are rare and expensive.There are ten known precious metals,three of which are of interest to investors,silver,gold,and platinum.The goal is to find physical methods to identify the presence of precious metals,silver,and gold in the metal components of the computer motherboard,and to confirm its presence by chemical methods for its use and its selling to the jewelry industry after it is physically separated from the computer motherboards.Physical and chemical tests were identified.Physical tests include inscription test,magnet test and specific gravity test for both silver and gold metal pieces and chemical tests include bleach test,nitric acid test,test karat solution kit,and jewelry test kits.展开更多
高速服务器主板主芯片到存储器的高速信号传输通过Double Data Rate(简称DDR)技术实现,传输高速信号的连接线简称为DDR阻抗线。因主芯片相对存储器位置能布设管脚的空间要小,从主芯片到存储器的DDR高速阻抗线呈扇出形状,主芯片位置的阻...高速服务器主板主芯片到存储器的高速信号传输通过Double Data Rate(简称DDR)技术实现,传输高速信号的连接线简称为DDR阻抗线。因主芯片相对存储器位置能布设管脚的空间要小,从主芯片到存储器的DDR高速阻抗线呈扇出形状,主芯片位置的阻抗线线宽相对存储器位置要小,存在阻抗不连续问题。对靠近主芯片位置的DDR阻抗线增加规则的凸耳状走线可提升整段DDR阻抗不匹配问题。增加规则的凸耳走线的阻抗线又称Tabbed Routiing阻抗(简称TAB阻抗)。探究布设不同形状和不同尺寸的TAB设计来提升阻抗不连续问题,根据材料等级选择一种最佳的布线设计模式,对TAB阻抗设计及生产制作控制都有较大指导意义。展开更多
Smog chambers are the effective tools for studying formation mechanisms of air pollution.Simulations by traditional smog chambers differ to a large extent from real atmospheric conditions,including light,temperature a...Smog chambers are the effective tools for studying formation mechanisms of air pollution.Simulations by traditional smog chambers differ to a large extent from real atmospheric conditions,including light,temperature and atmospheric composition.However,the existing parameters for mechanism interpretation are derived from the traditional smog chambers.To address the gap between the traditional laboratory simulations and the photochemistry in the real atmosphere,a vehicle-mounted indoor-outdoor dual-smog chamber(JNUVMDSC)was developed,which can be quickly transferred to the desired sites to simulate quasi-realistic atmosphere simultaneously in both chambers using“local air”.Multiple key parameters of the smog chamber were characterized in the study,demonstrating that JNUVMDSC meets the requirements of general atmospheric chemistry simulation studies.Additionally,the preliminary results for the photochemical simulations of quasi-realistic atmospheres in Pearl River Delta region and Nanling Mountains are consistent with literature reports on the photochemistry in this region.JNU-VMDSC provides a convenient and reliable experimental device and means to study the mechanism of atmospheric photochemical reactions to obtain near-real results,and will make a great contribution to the control of composite air pollution.展开更多
文摘Elements can be classified into metals,nonmetals,or metalloids based on their chemical and physical properties.Precious metals are rare and expensive.There are ten known precious metals,three of which are of interest to investors,silver,gold,and platinum.The goal is to find physical methods to identify the presence of precious metals,silver,and gold in the metal components of the computer motherboard,and to confirm its presence by chemical methods for its use and its selling to the jewelry industry after it is physically separated from the computer motherboards.Physical and chemical tests were identified.Physical tests include inscription test,magnet test and specific gravity test for both silver and gold metal pieces and chemical tests include bleach test,nitric acid test,test karat solution kit,and jewelry test kits.
文摘高速服务器主板主芯片到存储器的高速信号传输通过Double Data Rate(简称DDR)技术实现,传输高速信号的连接线简称为DDR阻抗线。因主芯片相对存储器位置能布设管脚的空间要小,从主芯片到存储器的DDR高速阻抗线呈扇出形状,主芯片位置的阻抗线线宽相对存储器位置要小,存在阻抗不连续问题。对靠近主芯片位置的DDR阻抗线增加规则的凸耳状走线可提升整段DDR阻抗不匹配问题。增加规则的凸耳走线的阻抗线又称Tabbed Routiing阻抗(简称TAB阻抗)。探究布设不同形状和不同尺寸的TAB设计来提升阻抗不连续问题,根据材料等级选择一种最佳的布线设计模式,对TAB阻抗设计及生产制作控制都有较大指导意义。
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.41877370 and 42077190)the China Postdoctoral Science Foundation(No.2021M691229)+2 种基金the fund of Creative Research Groups of NSFC(No.42121004)the Science and Technology Planning Project of Guangdong Province of China(No.2019B121202002)the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06N263).
文摘Smog chambers are the effective tools for studying formation mechanisms of air pollution.Simulations by traditional smog chambers differ to a large extent from real atmospheric conditions,including light,temperature and atmospheric composition.However,the existing parameters for mechanism interpretation are derived from the traditional smog chambers.To address the gap between the traditional laboratory simulations and the photochemistry in the real atmosphere,a vehicle-mounted indoor-outdoor dual-smog chamber(JNUVMDSC)was developed,which can be quickly transferred to the desired sites to simulate quasi-realistic atmosphere simultaneously in both chambers using“local air”.Multiple key parameters of the smog chamber were characterized in the study,demonstrating that JNUVMDSC meets the requirements of general atmospheric chemistry simulation studies.Additionally,the preliminary results for the photochemical simulations of quasi-realistic atmospheres in Pearl River Delta region and Nanling Mountains are consistent with literature reports on the photochemistry in this region.JNU-VMDSC provides a convenient and reliable experimental device and means to study the mechanism of atmospheric photochemical reactions to obtain near-real results,and will make a great contribution to the control of composite air pollution.
