铜与常见酸反应边界浓度的探究

以铜与各种酸发生反应时所需浓度作为探究内容,通过系列实验,发现铜分别与盐酸、硫酸开始发生反应的起始浓度、铜与硝酸反应生成NO的浓度以及与硝酸反应生成NO2的浓度,并得出相应结论。对实验及结论进行了讨论。

过饱和温度和降温速率对BBO晶体浓度边界层厚度的影响

浓度边界层是晶体生长过程中分析界面输运现象的重要元素。我们从实验角度研究了扩散机制下的BaB2 O4 单晶生长中过饱和温度和降温速率对浓度边界层厚度的影响。过饱和温度和浓度边界层厚度之间为抛物线关系 ,降温速率和浓度边界层厚度变化率之间为线性关系。

全息干涉法对气液流动浓度边界层的实验观测

Laser holographic interferometer system was used to visualize the concentration profiles within the vicinity of the gas-liquid interface under the co-current flowing conditions of gas/liquid two fluids.Interferograms on different experimental conditions were obtained,and the concentration profiles as well as the thickness of the concentration boundary layer were calculated.Finally the influence of the Reynolds number of the liquid phase on the boundary layer thickness was discussed.

结合空间插值的水污染浓度边界跟踪

针对水污染扩散浓度边界跟踪的问题,通过随机采样以及比较不同的拟合参数,对浓度场进行地统计学空间插值运算,重构污染源扩散浓度场,再根据浓度场重构时参数拟合的结果,采用模型预测控制方式,对水面移动机器人移动轨迹进行寻优,控制移动机器人移动并最终实现对污染扩散边界进行跟踪。仿真结果表明,该方法能够准确预测浓度场分布,并使得移动机器人快速跟踪到既定浓度边界,验证了该方法的有效性。

边界锡浓度的计算方法

说明了浮法玻璃在钢化过程中是否出现虹彩取决于涉锡面上边界锡浓度的达到大小,介绍了边界锡浓度与单位涉锡面上总含锡量的函数关系,解决了从化验室测得的单位涉锡面上总锡量直接换算成边界锡浓度的问题,使判断抗虹彩特性的依据成为可能。

2种四环素类抗生素对厌氧消化的最低抑制浓度和联合抑制类型

厌氧消化技术被广泛用于猪场废水的处理,为探明四环素类抗生素对猪场废水对厌氧消化产生抑制作用的边界浓度值,选用了2种常用的四环素类抗生素土霉素和金霉素作为抑制剂,用重铬酸钾法测出COD,以COD去除率反映抗生素的独立抑制和联合抑制效果,结果显示:土霉素、金霉素对厌氧消化的最低抑制浓度分别是0.3、0.1 mg/L,且2种抗生素的联合抑制效果大于单独抑制效果。

VOCs浓度监测在及时发现设备腐蚀泄漏中的应用

某石化企业在追求装置本质安全的前提下,更担负着节能减排的重大社会责任。该企业环境监察大队在VOCs日常监测中利用手持式VOCs检测仪多次发现设备腐蚀泄漏问题,设备泄漏过程中物料中的有机气体轻组分集中大量地排放到设备外部,造成装置区域局部VOCs浓度偏高,通常检测泄漏数据达到μg/g级,利用仪器逆向追查,根据VOCs浓度变化判断设备泄漏部位,进而追溯到泄漏点,及时避免腐蚀泄漏的进一步发生。利用VOCs浓度检测为发现设备管线的腐蚀泄漏提供一个新的思路,在保障设备本质安全的前提下,减少VOCs排放,为企业健康长远发展助力。

AgNO_3显色法判断氯离子渗透深度的影响因素

采用不同配合比混凝土试样进行非稳态电迁移(RCM,rapid chloride migration)试验,研究AgNO3显色法对判断氯离子渗透深度的影响.结果表明:相比实际的氯离子渗透边界,采用AgNO3显色法测量的氯离子渗透深度值偏小,用RCM法计算的快速氯离子扩散系数较实际结果小;氯离子显色边界浓度对其扩散系数计算值的影响较大,试验中不同边界浓度对氯离子扩散系数的影响可达20%以上;水泥基材料物相中Ca(OH)2的含量对氯离子边界浓度有较大影响,存在一定的函数关系,Ca(OH)2的含量越高,氯离子边界浓度越大;掺入粉煤灰后,氯离子显色的边界浓度减小,用AgNO3显色法测得的渗透深度相应增大,采用RCM测得的氯离子快速扩散系数偏大.

NaClO_3晶体生长过程光学诊断与数值模拟

运用光学干涉诊断方法实时观测NaClO3晶体生长过程,得到晶体生长过程中溶液浓度,晶体尺寸等物理参量.将这些参量与数值模拟得到的结果进行比对,研究重力条件下NaClO3晶体溶液生长过程中速度场、浓度场的分布与演化,尝试提出符合实际情况的晶体生长理论模型.对比两种方法得到的浓度边界层厚度,数值模拟得到了与实验数据相一致的结论.

化工原理课程中的类比教学法

类比教学法是将未知的研究对象与学生已熟知的研究对象进行比较,找出相同点或相似点。类比教学法不仅使学生加深对已有知识的理解和记忆,而且能从中受到启发和开拓思路,使较复杂的研究对象变得易于理解和掌握,收到事半功倍的效果。 化工原理是高等学校化工、轻工、制药类专业的一门重要的技术基础课程,我校药物制剂、药物化学、化学制药、生物制药、微生物制药等专业均开设了化工原理课程。化工原理课程的核心内容为涉及动量传递、热量传递和质量传递过程的化工单元操作。动量传递过程的规律相对简单,较易掌握。

景观植物在流域水污染修复中的应用研究

当前水污染修复过程中,污染边界不明确,导致水体中污染物浓度较高,应用景观植物进行流域水污染修复。计算景观植物板块面积,获取景观植物空间负荷指数,利用水流变化规律,划定水污染边界,根据景观植物的抗毒性特征,设置流域水污染修复模式。实验结果:在流域水污染修复中应用景观植物的净化能力,水体中污染物浓度范围在3.014(mg/L)~9.103(mg/L),比应用景观植物前下降了2.4(mg/L)左右,证明种植景观植物更有利于流域水污染修复。

MHD stagnation point flow by a permeable stretching cylinder with Soret-Dufour effects

Combined effects of Soret(thermal-diffusion) and Dufour(diffusion-thermo) in MHD stagnation point flow by a permeable stretching cylinder were studied. Analysis was examined in the presence of heat generation/absorption and chemical reaction. The laws of conservation of mass, momentum, energy and concentration are found to lead to the mathematical development of the problem. Suitable transformations were used to convert the nonlinear partial differential equations into the ordinary differential equations. The series solutions of boundary layer equations through momentum, energy and concentration equations were obtained.Convergence of the developed series solutions was discussed via plots and numerical values. The behaviors of different physical parameters on the velocity components, temperature and concentration were obtained. Numerical values of Nusselt number, skin friction and Sherwood number with different parameters were computed and analyzed. It is found that Dufour and Soret numbers result in the enhancement of temperature and concentration distributions, respectively.

Research on an Algorithm of Shape from Shading

Shape from shading(SFS)is an important domain in computer vision.The paper presented an improved algorithm of shape from shading based on a single image according to an existed one.The presented algorithm enhanced the boundary constraints to eliminate the rotation distortion on the border of reconstructed object and introduced the factor of brightness error to weaken the influence irradiance equation’s nonlinearity on reconstructed errors.The reconstructed results verify the performance improvement in terms of accuracy by the input image of a synthetic image and a real image of weld.

非共沸混合工质喷射器内部流动特性

为了探究混合工质喷射器内部流体的流动特性及传热传质机理,运用气体动力学函数法建立了混合工质喷射器动力学模型。基于所设计的非共沸混合工质(R32/R245fa)喷射器结构尺寸,建立二维稳态轴对称模型,开展了混合工质喷射器特性的数值模拟研究。分析了混合工质喷射器内部流体的速度场、压力场、温度场及浓度场变化规律。研究结果表明:混合工质喷射器内速度场、压力场、温度场及浓度场具有较好的动力学特性,其喷射因数比纯工质(R245fa)喷射器提高了78.95%,为混合工质喷射器优化设计提供了理论依据。

Flow of Casson nanofluid with viscous dissipation and convective conditions: A mathematical model

The magnetohydrodynamic(MHD) boundary layer flow of Casson fluid in the presence of nanoparticles is investigated.Convective conditions of temperature and nanoparticle concentration are employed in the formulation. The flow is generated due to exponentially stretching surface. The governing boundary layer equations are reduced into the ordinary differential equations. Series solutions are presented to analyze the velocity, temperature and nanoparticle concentration fields. Temperature and nanoparticle concentration fields decrease when the values of Casson parameter enhance. It is found that the Biot numbers arising due to thermal and concentration convective conditions yield an enhancement in the temperature and concentration fields. Further, we observed that both the thermal and nanoparticle concentration boundary layer thicknesses are higher for the larger values of thermophoresis parameter. The effects of Brownian motion parameter on the temperature and nanoparticle concentration are reverse.

Numerical Solution of Some Diffusion Problems in 3-Layered 3D Domain

In this paper we consider averaging and finite difference methods for solving the 3-D boundary-value problem in a multilayered domain. We consider the metal concentration in the 3 layered peat blocks. Using experimental data the mathematical model for calculating the concentration of metal at different points in peat layers is developed. A specific feature of these problems is that it is necessary to solve the 3-D boundary-value problems for the partial differential equations （PDEs） of the elliptic type of second order with piece-wise diffusion coefficients in the three layer domain. We develop here a finite-difference method for solving a problem of the above type with the periodical boundary condition in x direction. This procedure allows reducing the 3-D problem to a system of 2-D problems by using a circulant matrix.

NO_x Release from Snow and Ice Covered Surface in Polar Regions and the Tibetan Plateau

The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosphere and may have a crucial impact on the air signals that are retrieved from ice cores. In the recent years, sunlit snow and ice have been demonstrated to be important NOx sources in the polar atmospheric boundary layer. This paper makes a thorough review on the release of NOx from snow and ice, including field observations and experimental evidences, release mechanisms and influential parameters that affect such a release process, polar NOx concentrations and fluxes, and environmental impacts of the chemical processes of NOx in the polar atmospheric boundary layer. In the Tibetan Plateau, the released NOx observed recently in the sunlit snow/ice-cover is 1-order magnitude more than that in polar regions, but further scientific research is still needed to reveal its impact on the atmospheric oxidizing capacity.

基于一般浓度入射条件的汽车扬尘数值模拟研究

数值模拟是研究汽车扬尘时空分布的重要方法,地面扬尘浓度条件则是数值模拟求解的关键。不同于已有的整体均匀入射或局部单一强度入射条件,由风沙理论推导了更合理的一般浓度边界条件,在此基础上研究了颗粒重力及车轮旋转对扬尘的影响,并得出车速与扬尘量之间近似为指数的关系。这一方法对进一步研究汽车造成的污染问题具有积极的作用。

硝酸银显色法检测混凝土中氯离子的迁移

实验室和工程现场经常用硝酸银显色法检测混凝土中氯离子的迁移。有3种硝酸银显色法,即AgNO3+K2CrO4法、AgNO3+荧光素法以及AgNO3法,其中AgNO3法使用最广泛,因为AgNO3法测试结果和其他两种方法相似却比其他两种方法容易操作。硝酸银显色法测量的变色边界氯离子浓度在很大范围内变化,很多因素诸如混凝土碱度、硝酸银浓度、取样方法以及混凝土中氯离子分析方法等均会对变色边界氯离子浓度测试结果产生影响。采用硝酸银显色法测试的自由氯离子渗透深度以及通过变色边界自由氯离子浓度计算的表观扩散系数可以简单、快速地评价混凝土抗氯离子渗透性。

硝酸银显色法测量混凝土氯离子表观扩散系数

研究了硝酸银显色法快速测量混凝土中氯离子表观扩散系数。将14组混凝土试件分别在16.5%与3.5%NaCl溶液中浸泡90d和300d,用AgNO_3显色法及NT Build 443法测量其氯离子表观扩散系数(D_A和D_N)。结果表明:用浸泡液浓度为表面氯离子浓度情况下,当表层氯离子浓度与浸泡液氯离子浓度相近时,D_A与D_N值相近;浸泡90 d时,一部分D_A与D_N值相近;浸泡300 d时,所有的D_A与D_N均十分相近。测量的表层氯离子浓度作为表面氯离子浓度时,所有D_A和D_N均十分接近。因此,合理确定表面氯离子浓度后,硝酸银显色法可以快速且较为精确地测量混凝土氯离子表观扩散系数。