沿海软粘土取土质量的对比分析

本文在简要介绍固定活塞式薄壁取土器取土技术基础上，详尽分析了在连云港、赤湾港和广深路所进行的软粘土取土技术对比试验结果。试验结果表明，土样扰动对于室内所测定的力学性指标影响极大，但对物理性指标影响不大。研究结果还有力地证明，只要操作正确，采用薄壁取土器能取得高质量土样，而采用敞口式厚壁取土器取出的土样扰动较大。     

一种获得材料各层面红外光谱的有效工具——OMNI采样器

本文介绍了一种获得材料各层面红外光谱的有效工具－－OMNI采样器，并以麦秸、光导纤维为例，研究了它们各层面的化学成分的分布，探讨了使用OMNI采样器应注意的一些问题。     

A new method for accelerating the rate of convergence of the simple-like algorithm

A pressure correction formula is proposed for the SIMPLE-like algorithm in order to improve the rate of the convergence when solving laminar Navier–Stokes equations when there is rapidly varying pressure. Based on global mass conservation, a line average pressure correction is derived by integration of the momentum equation for approximate one-dimensional flow. The use of this formula with the SIMPLE-like algorithm can rapidly build up the pressure distribution in the region where the pressure undergoes a very large change, which normally causes the rate of convergence of the SIMPLE or the SIMPLEC schemes to be slow. In order to illustrate the technique, the performances of SIMPLE and of SIMPLEC with the average pressur correction are investigated for axisymmetric flow past and through a sampler. A comparison of these two techniques shows that the average pressure correction proposed in this paper significantly accelerates the rate of convergence.     

易挥发液体样品采样器(Ⅱ型)的研制及性能

研究了一种易挥发液体样品采样器（Ⅱ型），它具有采样准确、使用方便、容易清洗和携带等优点，配合气相色谱仪，可满足轻质油品等易挥发液体样品的采样分析要求。     

数字化温湿度采集仪的研制

在日常生产活动中,很多场合需要进行温度、湿度测量。为了达到对温湿度的精确测量,设计并实现了一种数字化温湿度采集仪。该采集仪以89S52单片机为核心,具有温湿度采集范围广、精度高、抗干扰能力强、接口丰富、使用灵活等优点。采集仪既可以作为单机仪器,也可以通过RS485组成网络化测试系统。作为单机仪器时,有大屏幕的LCD(128*64)显示实时的温、湿度和露点温度。通过对现场试验测试并对结果进行分析,表明该采集仪完全满足测量要求,有较高的使用价值。     

A numerical method for accelerating the rate of convergence of the SIMPLE-like algorithm for flow through a thin filter

The control volume, finite difference method and the k-? tubulence model are employed in a numerical simulation of the turbulent fluid flow both outside and inside a blunt cylindrical sampler which houses a paper filter in its chamber. The presence of a paper filter, which has a very large resistance, results in a large pressure drop across the filter and this causes difficulties in making the SIMPLE or the SIMPLEC scheme converge. In order to improve the rate of convergence of the SIMPLE-like algorithm when the resistance of the filter is very large, an average pressure correction formula is proposed. Based on global mass conservation, a line average pressure correction for the paper filter is derived using a modified Darcy law for a porous medium. A combination of this formula and the SIMPLE-like algorithm can rapidly build up the pressure drop across the filter and hence dramatically improve the rate of convergence of the iterative scheme. Comparisons of the convergence histories and the numerical results for the fluid flow when using SIMPLE and SIMPLEC with the average pressure correction method show that the average pressure correction method for dealing with the paper filter significantly accelerates the rate of convergence of the iterative scheme.     

Combination of a Mid-infrared Hollow Waveguide Gas Sensor with a Supported Capillary Membrane Sampler for the Detection of Organic Compounds in Water

A Fourier transform infrared (FT-IR) spectroscopy based gas sensor for continuous analysis of liquid phase samples has been developed, coupling a short hollow waveguide (HWG) gas cell with a supported capillary membrane sampler (SCMS) probe. Passing an inert carrier gas through the thin-walled tubular silicon membrane enables the permeation of volatile organic compounds (VOCs) present in aqueous solution and facilitates their continuous and quantitative detection in the infrared hollow fiber by multiple internal reflection spectroscopy. The sensitivity of the sensor system has been determined at the ppb (μg/L) concentration level and the response time ranges from few minutes to 30 min, depending on the analyte and the permeation properties of the sampling membrane.

The experimental set-up consists of Bruker Vector 22 FT-IR spectrometer with an externally aligned 50 cm long silica HWG coupled to the SCMS, which is immersed into a glass flask filled with analyte solution and kept under constant stirring.

Aqueous solutions of benzene, toluene, xylene isomers and chloroform were qualitatively and quantitatively analyzed confirming the feasibility of this sensor approach for environmental analysis.     

The effects of sampling materials selection in the collection of reduced sulfur compounds in air

In this study, the analytical bias in the measurements of reduced sulfur compounds (RSC) was investigated in terms of sorptive loss caused by the materials selected for the sample introduction. For the purpose of this study, three vacuum samplers made in the combination of different vacuuming efficiencies (e.g., rapid versus slow sampling) and different materials (i.e., Teflon versus stainless steel (SS)) were tested to evaluate the sampling recovery rate (RR) for five RSCs: H₂S, CH₃SH, DMS, CS₂ and DMDS. To make a parallel comparison of RR, the RSC standard samples contained in one bag were transferred to another bag using each sampling system. Their relative contents between, before, and after the transfer were then evaluated between different samplers to assess the sampling bias caused by the interaction between RSC and the sampling material. In the case of the most reactive compound, H₂S, the sampling loss from the SS inlet line amounted to as high as 45%, while that for the Teflon counterpart was almost insignificant. When the sampling time was arbitrarily elongated (i.e., use of a slow sampler), the sampling loss rate of the SS inlet sampler became more significant with the RR values dropping down from 55 to 70%, across different RSCs. The overall results of our comparative study indicate that the sampling system for the reactive gaseous compounds should be checked for the material feasibility to guarantee sufficient analytical reliability.     

First Hitting Time Analysis of the Independence Metropolis Sampler

In this paper, we study a special case of the Metropolis algorithm, the Independence Metropolis Sampler (IMS), in the finite state space case. The IMS is often used in designing components of more complex Markov Chain Monte Carlo algorithms. We present new results related to the first hitting time of individual states for the IMS. These results are expressed mostly in terms of the eigenvalues of the transition kernel. We derive a simple form formula for the mean first hitting time and we show tight lower and upper bounds on the mean first hitting time with the upper bound being the product of two factors: a “local” factor corresponding to the target state and a “global” factor, common to all the states, which is expressed in terms of the total variation distance between the target and the proposal probabilities. We also briefly discuss properties of the distribution of the first hitting time for the IMS and analyze its variance. We conclude by showing how some non-independence Metropolis–Hastings algorithms can perform better than the IMS and deriving general lower and upper bounds for the mean first hitting times of a Metropolis–Hastings algorithm.     

超声波空气污染物颗粒采样器的新结构及其特性研究*

超声波空气污染物颗粒采样器具有可采集低浓度颗粒污染物、采样速度快、重复性好、结构简单、易分析被采集物以及不破坏污染物成分等优点。为了进一步提高其采样效率,该文提出了一种超声波空气污染物颗粒采样器的新结构。该采样器由超声换能器、被粘接在换能器声辐射面上的圆形声辐射板以及与声辐射板平行的采样板组成。该采样器利用声辐射力和声学流场驱动空气中的污染物颗粒快速聚集到采样板上。样机测试表明,该结构在空气污染物颗粒初始浓度为4 mg/L以及辐射板中心位置的振动速度为0.29 m/s时,对烟雾中PM2.5和PM2.5-10颗粒的采样效率为16.3 mg/m~2·min·W。与不采用高阶弯曲振动圆形声辐射板的结构相比,其采样效率增加了110%。