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991.
A multidimensional gas chromatography method for the analysis of hydrogen sulfide in crude oil and crude oil headspace
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Darcy B. Hager 《Journal of separation science》2014,37(24):3649-3655
Two‐dimensional heart‐cutting gas chromatography is used to analyze dissolved hydrogen sulfide in crude samples. Liquid samples are separated first on an HP‐PONA column, and the light sulfur gases are heart‐cut to a GasPro column, where hydrogen sulfide is separated from other light sulfur gases and detected with a sulfur chemiluminescence detector. Heart‐cutting is accomplished with the use of a Deans switch. Backflushing the columns after hydrogen sulfide detection eliminates any problems caused by high‐boiling hydrocarbons in the samples. Dissolved hydrogen sulfide is quantified in 14 crude oil samples, and the results are shown in this work. The method is also applicable to the analysis of headspace hydrogen sulfide over crude oil samples. Gas hydrogen sulfide measurements are compared to liquid hydrogen sulfide measurements for the same sample set. The chromatographic system design is discussed, and chromatograms of representative gas and liquid measurements are shown. 相似文献
992.
993.
994.
A robust 2 × 2 photonic switch based on multimode interference (MMI) effects is proposed. We demonstrate that the device is
very tolerant to material modifications and typical fabrication errors. This is a result of the MMI design and the high symmetry
of the switch. The key parameter for the operation of the device is that the input light forms a pair of well defined self-images
exactly in the middle of the switch. The index modulated regions precisely overlap the positions where these two self-images
are formed. By creating identical contact features at these locations, any refractive index change induced in the material
as a result of electrical isolation will be replicated in both self-images, and therefore the off-state output will not be
altered. In the same way, offset and dimension errors are reflected symmetrically on both self-images and do not seriously
affect the imaging. The characteristics of the switch under different scenarios are investigated using the finite difference
beam propagation method. By employing this configuration, crosstalk levels better than −20 dB are achievable over a wavelength
range of 100 nm while maintaining polarization independence. 相似文献
995.
神龙一号电子束束参数测量系统猝发式的精确触发方式研究 总被引:1,自引:0,他引:1
为了准确了解电子束随时间变化的性能, 在神龙一号直线感应加速器上进行电子束束参数测量时要求测量系统精确地同步于电子束的产生和输运. 其功率系统开关放电波形后沿幅度高达250kV, 下降时间约20ns, 并且从该下降沿到电子束打靶的时间有145ns, 抖动1—2ns, 非常稳定; 如果以陡峭的后沿作为测量时间基准, 则可以获得与其抖动相同量级的同步精度. 因此通过对其波形的下降沿进行微分来获取测量系统的触发信号, 选择合适的微分参数可以得到对应于下降沿
约ns级精度的测量时间基准, 通过采用光纤驱动电路完全消除了高压开关对低压测量系统的干扰, 保证测量系统正常工作. 该方法消除了传统触发方式因延时长、精度低、抖动大等对确定测量时间基准的不利影响, 满足了使用高速测量设备准确获取电子束不同时刻的束参数波形的精确触发要求. 相似文献
997.
The focal switch of cosine-Gaussian (CsG) beams passing through a system with the aperture and lens separated is studied analytically
and numerically. It is shown that the focal switch of CsG beams can appear not only for the apertured case, but also for the
unapertured case. The necessary condition for the focal switch is that truncation parameter α > αc and the beam parameter β > βc, αc, βc being the corresponding critical values. There exists a maximum of the relative transition height Δz
sw as α varies, and Δz
sw increases with increasing β and decreasing N
w. The normalized axial intensity minimum I
min / I
max decreases with an increase of α and β, and I
min / I
max remains unchanged as N
w varies. 相似文献
998.
应用CMOS电路开关级设计技术对超前进位全加器进行了设计,并用PSPICE模拟进行了功能验证.与传统门级设计电路相比,本文设计的超前进位电路使用了较少的MOS管,并能保持原有的传输延迟. 相似文献
999.
In this paper, the evolution of the gradient force pattern, focal shift, and focal switch induced by a three-portion pure phase-shifting apodizer is numerically investigated in detail. The results show that the proposed apodizer may induce tunable gradient force on the particles in the focal region, focal shift, and focal switch. By adjusting the geometrical parameters of the phase-shifting apodizer, multiple traps may occur with changeable distance between them, and the shape of the optical trap also evolves evidently. More interestingly, for certain geometrical parameters of the proposed apodizer, by changing the phase shift of inner annular portion, the considerable focal shift may occur with focal switch accompanying, which is discussed to show that this kind of apodizer may be a very promising method of transporting trapped particles. 相似文献
1000.
增强吸收型光双稳的耦合动力学方程及动态分析 总被引:1,自引:1,他引:0
本文从唯象的角度首次提出了增强吸收到光双稳的耦合动力学方程,利用计算机模拟,描述了增强吸收型光双稳的静态和动态特性。 相似文献