Enhancement of optical emission generated from femtosecond double-pulse laser-induced glass plasma at different sample temperatures in air

In double-pulse laser-induced breakdown spectroscopy(DP-LIBS), the collinear femtosecond double-pulse laser configuration is experimentally investigated with different initial sample temperatures using a Ti:sapphire laser. The glass sample is ablated to produce the plasma spectroscopy. During the experiment, the detected spectral lines include two Na(I) lines(589.0 nm and 589.6 nm) and one Ca(I) line at the wavelength of 585.7 nm. The emission lines are measured at room temperature(22 ℃) and three higher initial sample temperatures(T_s?=?100 ℃, 200 ℃, and 250 ℃). The inter-pulse delay time ranges from-250 ps to 250 ps.The inter-pulse delay time and the sample temperature strongly influence the spectral intensity,and the spectral intensity can be significantly enhanced by increasing the sample temperature and selecting the optimized inter-pulse time. For the same inter-pulse time of 0 ps(single-pulse LIBS), the enhancement ratio is approximately 2.5 at T_s?=?200 ℃ compared with that obtained at T_s?=?22 ℃. For the same inter-pulse time of 150 ps, the enhancement ratio can be up to 4 at T_s?=?200 ℃ compared with that obtained at T_s?=?22 ℃. The combined enhancement effects of the different initial sample temperatures and the double-pulse configuration in femtosecond LIBS are much stronger than that of the different initial sample temperatures or the double-pulse configuration only.     

地质矿产勘查风险成因及防范措施

矿物地质勘查过程不光滑。它可能出现在市场价格预测失败,财产损失和自然因素或人为因素造成的人为因素的勘探和预测过程中,以及矿床地质条件的变化。以及所产生的预期返回,无法完成经济风险。     

Effect of distances between lens and sample surface on laser-induced breakdown spectroscopy with spatial confinement

Spatial confinement can significantly enhance the spectral intensity of laser-induced plasma in air.It is attributed to the compression of plasma plume by the reflected shockwave.In addition,optical emission spectroscopy of laser-induced plasma can also be affected by the distance between lens and sample surface.In order to obtain the optimized spectral intensity,the distance must be considered.In this work,spatially confined laser-induced silicon plasma by using a Nd:YAG nanosecond laser at different distances between lens and sample surface was investigated.The laser energies were 12 mJ,16 mJ,20 mJ,and 24 mJ.All experiments were carried out in an atmospheric environment.The results indicated that the intensity of Si (I) 390.55 nm line firstly rose and then dropped with the increase of lens-to-sample distance.Moreover,the spectral peak intensity with spatial confinement was higher than that without spatial confinement.The enhancement ratio was approximately 2 when laser energy was 24 mJ.     

流体输送的经济管径和经济保温厚度

以流体输送的年操作费用与管线投资的年折旧费用之和最小作为目标函数,关联出无保温的低温流体和保温的热流体求解经济管径的数学模型及相应的PC-1500计算机计算程序.     

高应力红页岩巷道失稳机理与控制技术研究

为解决高应力红页岩巷道的维护难题,以平安磷矿二矿为工程背景,采用理论分析、数值模拟、室内测试及工业性试验等方法,研究了红页岩的微观结构特征及巷道失稳机理。研究表明:红页岩内部孔隙孔径主要集中在0~50nm与10~200μm的范围内。自然状态下孔径在10~200μm的微孔隙占总孔隙体积的37.45%,吸水后占比增加至45.82%,吸水后引发的岩石强度弱化是红页岩巷道失稳破坏的重要原因。提出了高强锚注+格栅拱架+小孔径锚索的高应力红页岩巷道支护对策,该支护结构能够适应红页岩巷道初期的变形要求,有效限制巷道出现过大的变形,并充分调动深部围岩的承载能力。现场监测表明红页岩巷道两帮最大变形量在100mm以内,顶板下沉量控制在40mm以内,锚索受力在100～120kN并趋于稳定,表明新方案控制效果良好。     

能量回收系统的热力学分析

石油化工装置使用的能量由能量转换和能量回收两部分构成。能量回收系统起着减少供入能，降低能耗的重要作用。经分析提出了换热设备和换热网络损失计算方法，分析了传热温差对能量回收的影响，指出减少传热温差是减少过程损、提高能量回收率的重要途径；讨论了能量回收系统能量回收的限度及存在的热力学和经济两个限制点，经济限制点是技术经济优化的结果，是合成换热网络遵照的依据；最后，讨论了分析和夹点技术在节能中的作用及其关系。     

催化裂化再生烟气CO器外燃烧技术及其应用

对催化裂化再生烟气CO的燃烧和利用进行了研究.通过实验室燃烧研究,测定出再生烟气CO燃烧的启燃温度和爆燃温度,根据试验数据关联出CO启燃过程的经验动力学方程.测试了高温(爆燃温度以上)CO燃烧数据,探索了高温燃烧速度.该技术已在金陵石化公司南京炼油厂和巴陵石化公司长岭炼化总厂等工业装置上应用.在工业装置的标定中考察了CO燃烧炉补燃量和配风量对再生烟气CO燃烧的影响.该技术燃烧稳定,操作灵活,不仅回收了燃烧热能,节约燃料,取得了很大经济效益,而且燃尽了CO,保护了环境.     

炼厂散热的实用计算和经济分析

为适应炼厂对节能的测算、分析以及减少散热损失的需要,本文提出:(1)快速、准确地计算表面散热损失的算图和小型计算机程序;(2)确定(火用)-经济分析的管线经济保温厚度的方法和计算机程序;(3)裸露金属表面散热状况及保温措施的技术效果;(4)进行环境温度、装置负荷率、装置规模对散热单耗影响的定量分析。