黄土高原多沙粗沙区高含沙水流发生频率的时间变化

高含沙水流的频繁发生是黄土高原多沙粗沙区产生高强度侵蚀的重要原因。本文基于1967—1989年的系列泥沙资料和面雨量资料，分析了黄土高原多沙粗沙区8个流域高含沙水流发生频率随时间的变化过程。根据其不同的变化趋势，将研究区所有流域分成了两类。第一种类型高含沙水流发生频率随时间逐渐减小；第二种类型高含沙水流随时间呈先减小后增大的变化趋势。从汛期降雨量（6—9月）及人类活动（包括人为的减沙活动和人为增沙活动）两个方面对高含沙水流随时间变化趋势的产生原因进行了分析。结果表明，第一种类型主要受到同期汛期降雨量的减少以及各种水利水保措施减沙量从上世纪60一80年代逐渐增大的影响；第二种类型的流域在上世纪60年代末到80年代初高含沙水流发生频率的减小主要是因为上世纪60、70年代大量修建的淤地坝在70年代发挥了显著的拦减泥沙的作用；但到了80年代以后，新建淤地坝很少。原有淤地坝已大部失效，另外人为的增沙活动，如修路、开矿、建窑等活动在80年代以后显著增加，上述因素促使高含沙水流发生频率在80年代初期以后呈随时间增加的趋势。     

Influence of residual milk-clotting enzyme and proteolysis on melting properties of soft cheese

In this work, we assessed the influence of coagulant residual activity and primary proteolysis on Cremoso Argentino cheese melting properties. For that purpose, we made Cremoso soft cheeses using different amounts of coagulant, and also obtained samples in which milk-clotting enzyme was inactivated. Primary proteolysis correlated with residual activity of coagulant in early stages of cheese ripening; however, it was similar in all cheeses after 30 days. The hydrolysis of caseins did not significantly affect the melting ability of the cheeses, expressed as the area increase after heating samples under standardized conditions. Samples with similar proximate composition showed some changes in meltability; those seemed related to pH evolution during ripening.     

长期在地下工作后的塑料排水板的性能研究

塑料排水板在软基工程施工后期及竣工后的工作性状对于工后沉降的控制起着重要作用,目前国内对塑料排水板长期工作后的性能研究几乎是空白。本文通过现场开挖采取在地下工作2年后的塑料排水板试样进行室内检测,并与施工前性能进行对比分析。结果表明:工作2年后,塑料排水板基本无磨损,芯板齿槽保持较好;而排水板复合体干态抗拉强度及滤膜干态抗拉强度明显降低,折减系数分别为81%~88%5、9%~90%;通水量减小,弯折的排水板通水量减小的可能性更大,部分数据达不到设计要求,对工程后期排水固结将产生不利影响。     

针梁台车在大花水水电站引水隧洞混凝土衬砌施工中的改进

大花水水电站引水隧洞由于前期开挖工期略有滞后，为加快施工进度，结合全圆断面的施工特点，大部分引水隧洞采用了全圆针梁穿行式钢模台车进行混凝土衬砌。通过各参建单位对针梁台车的运用和改进，有效地提高了引水隧洞混凝土的衬砌速度，并确保了工程质量。     

川中丘陵区一种新型小流域径流输沙模型的建立与应用

径流输沙模型对定量评价水沙的输出响应具有重要的意义。本研究在已有研究成果的基础上，通过对四川盐亭县林山西沟小流域的径流、泥沙进行现场观测与分析，提出含沙量单位线的定义及其确定方法，建立了适应该小流域的径流输沙模型。并应用实测资料进行比较，表明模型的模拟结果可靠，模拟过程确定性系数达0．8以上，为川中丘陵区小流域径流输沙过程的预测预报提供了一个新方法。     

川中地区上三叠统天然气地球化学特征及成藏过程探讨

川中地区上三叠统是一套自生自储的天然气成藏系统，天然气中甲烷含量为88%～96％，重烃（C2＋）含量一般在6％～9％之间，二氧化碳和硫化氢等非烃气体含量普遍较低；天然气干燥系数（C1／C2＋）为5～15，并且随深度增加而呈现升高的趋势；天然气和凝析油轻烃中的甲基环己烷、庚烷和异庚烷值变化表明天然气主要来源于腐殖型母质；天然气甲烷和乙烷碳同位素分别为-39．00‰～-41．00‰和-25．00‰～-27．00‰，具有典型煤成气特征。川中地区上三叠统烃源岩在燕山期持续沉降埋藏过程中，达到高成熟早期阶段；在喜山期，该地区大约2500m地层的剥蚀，使地层温度和压力大幅度降低，故储层中早期低成熟残余天然气的卸压膨胀作用和水溶气的脱溶作用为晚期天然气聚集成藏提供了重要的气源，同时也使气藏中甲烷碳同位素变轻。     

Evaporation and Evolution of Suspended Solution Droplets at Atmospheric and Reduced Pressures

Thermal history and solute precipitation behavior of suspended solution droplets of sodium chloride (NaCl), magnesium sulphate (MgSO₄), and zirconium hydroxychloride (ZrO(OH)Cl) evaporating at atmospheric and reduced pressures are studied. Experimental measurements on the variation of droplet diameter, solution concentration, and temperature during the evaporation period are presented and discussed. The results of solute precipitation behavior in solution droplets observed under an optical microscope are displayed and discussed. Results indicate that reducing the pressure (∼ 33 kPa) results in a change in the solution droplet evaporation rate, but the thermal histories of a particular solution droplet are similar at the atmospheric and reduced pressures. At atmospheric and reduced pressures used in this study, the d² law for solution droplets is valid at early stages of the evaporation and before the solute precipitation initiates. Drying of MgSO₄ and ZrO(OH)Cl solution droplets results in the formation of spherical particles, whereas drying of spherical NaCl solution droplets results in the formation of cubic particles.     

降温集油技术在朝阳沟油田的应用

精确界定油井温度界限值,对回油温度进行自动控制是降低气耗、能耗的有效措施。首先推导了单井温度界限数值模型,然后针对朝阳沟油田的实际情况对油井进行了分类,并选择了有代表性的单(环)井进行了试验。通过现场实测值与利用模型计算的预测值比对,符合率达到了70%以上。在此基础上利用温度界限分析仪进行了进一步的验证试验,结果符合预期。在单(环)井上加装了掺水量自动控制装置,实现了回油温度的自动控制。     

An investigation of water-gas transport processes in the gas-diffusion-layer of a PEM fuel cell by a multiphase multiple-relaxation-time lattice Boltzmann model

In order to study water-gas transport processes in the gas-diffusion-layer (GDL) of a proton exchange membrane (PEM) fuel cell system, a multiphase, multiple-relaxation-time lattice Boltzmann model is presented in this work. The model is based on the mean-field diffuse interface theory and can handle the multiphase flows with large density ratios and various viscosities. By using the standard bounce back boundary condition and an approximate average scheme for the non-slip and wetting boundary walls, respectively, detailed liquid-gas transportation in the GDL, in which exact boundary condition is difficult to be implemented, can be simulated. Unlike most of lattice Boltzmann methods based on the Bhatnagar–Gross–Krook collision operator, the present model shows a viscosity-independent velocity field, which is very important in simulating multiphase flows where various viscosities coexist. We validate our model by simulating a static droplet on a wetting wall and compare with theoretical predictions. Then, we simulate a water-gas flow in the GDL of a PEM fuel cell and investigate the saturation-dependent transport properties under different conditions. The results are shown to be qualitatively consistent with the previous numerical and theoretical works.     

水下高围压磨料射流装置及冲蚀性能的研究

提出了水下高围压磨料射流切割模拟试验装置并对其进行了试验，得到了冲蚀深度与靶距，模拟水深，射流管长度及冲蚀时间的关系。同时对空气中磨料射流与纯水射流的冲蚀性能也进行了比较，本文较全面地揭示了水下磨料射流的冲蚀性能，为实际应用提供了必要的依据。