NH_4SCN解吸剂对负载Re的D296树脂的解吸影响

为了实现离子交换树脂中吸附离子的高效解离,研究了NH_4SCN解吸剂对负载Re的D296树脂的解吸影响,并探讨了其最优解吸工艺.通过静态实验探讨了解吸时间、解吸温度,以及解吸溶液的浓度和p H值对D296树脂的解吸影响,并测定了相应的解吸曲线.结果表明,NH_4SCN解吸剂对D296树脂的最佳解吸温度为323 K,最佳pH值为10,最佳解吸溶液浓度为100 g·L~(-1).在最佳解吸工艺条件下,反应20 min后,D296树脂中Re的解吸率可达98%以上,且解吸反应为吸热反应.当NH_4SCN解吸剂的流速为2 m L·min~(-1)时,淋洗效果较好.     

考虑环境温度的电动汽车充电负荷预测

为了保证电动汽车充电负荷预测更加准确、合理,分析环境温度导致电池特性、空调能耗和道路状况的变化对电动汽车充电需求的影响。考虑环境温度因素,引入能耗因子计算单位里程耗电量,利用蒙特卡洛法计算单辆车的充电负荷需求,再累加到总的充电负荷曲线上。以2020年上海市电动汽车为例仿真计算,验证了在不同温度影响下,电动汽车充电负荷会发生明显的变化。     

太阳能喷射-压缩复合制冷系统的实验及仿真

建立了太阳能喷射-压缩复合制冷系统的实验研究平台,基于EES软件程序进行系统稳态仿真,实验验证了仿真模拟程序的正确性,分析了不同发生温度、中间温度对系统性能的影响。研究表明,在中间温度和冷凝温度不变的情况下,随着发生温度的升高,总功率先降低后升高,系统EER先升高后降低;同时,系统COP呈先逐渐升高而后降低的趋势。在研究范围内,最优发生温度工作区域为78~80℃,此时,系统的总耗功量最小;最优中间温度工作区域为7~10℃,此时,系统制冷量达2 245 W,EER最高为3.39。     

中亚瓦赫什河上游源区气候水文要素演变特征

为研究全球变化背景下中亚河流源区气候水文变化,基于中亚跨境河流瓦赫什河上游源区1955—2017年气象水文数据,分析了流域内气候水文要素演变特征及流量变化主要控制因子。结果表明:瓦赫什河上游源区近1955—2017年气候呈现暖湿化趋势;瓦赫什河上游源区气温在1994年发生突变现象,降水在2007年与2012年发生突变现象,流量则在2003年发生突变现象;小波分析显示瓦赫什河上游流域气温、降水、流量的第一主周期分别为28 a、20 a、28 a,周期性振荡明显;瓦赫什河上游源区在气候水文要素关联上,气温与流量变化相较于降水紧密,但受全球升温停滞影响,温度对于流量作用并没有持续增强。     

Recent warming of Tonle Sap Lake,Cambodia: Implications for one of the world’s most productive inland fisheries

Tonle Sap Lake in Cambodia is arguably the world's most productive freshwater ecosystems, as well as the dominant source of animal protein for the country. The rapid rise of hydropower schemes, deforestation, land development and climate change impacts in the Mekong River Basin, however, now represent serious concerns in regard to Tonle Sap Lake's ecological health and its role in future food security. To this end, the present study identifies significant recent warming of lake temperature and discusses how each of these anthropogenic perturbations in Tonle Sap's floodplain and the Mekong River Basin may be influencing this trend. The lake's dry season monthly average temperature increased by 0.03°C/year between 1988 and 2018, being largely in synchrony with warming trends of the local air temperature and upstream rivers. The impacts of deforestation and agriculture development in the lake's floodplain also exhibited a high correlation with an increased number of warm days observed in the lake, particularly in its southeast region (agriculture R² = .61; deforestation R² = .39). A total of 79 dams, resulting in 72 km³ of volumetric water capacity, were constructed between 2003 and 2018 in the Mekong River Basin. This dam development coincided with a decreasing trend in the number of dry season warm days per year in the lower Mekong River, while Tonle Sap Lake's number of dry season warm days continued to increase during this same period. The present study revealed that Tonle Sap Lake's temperature trends are highly influenced by temperature trends in the local climate, agriculture development and deforestation of the lake's watershed. Although there were no noticeable impacts observed from upstream dam development in the Mekong River Basin, local‐to‐regional agricultural and land management of the lake's watershed appear to be effective strategies for maintaining a stable thermal regime in the lake in order to facilitate maximum ecosystem health.     

国家自然科学基金项目（51769017、51969018）

针对现有碾压混凝土坝温度场预警多是基于单个测点进行分析这一不足,提出了利用多测点综合信息预警的模式和方法。采用概率原理对温度监测值的有序度和无序度进行了定义,基于投影追踪法,确定了各测点的权重分布;根据温度场有序到无序的演变规律,结合有序度和测点权重分布,构建了能描述碾压混凝土坝温度场有序性的权重熵;借助典型小概率原理,提出了碾压混凝土坝温度场预警准则。实例分析表明：权重熵的变化规律与温度实测值变化规律相吻合,从而验证了该方法的可行性和有效性。     

高温气候下沥青混凝土心墙连续碾压施工结合面温控试验研究

在夏季高温气候沥青混凝土心墙连续多层施工时,为减少等待结合面温度降至规范要求上限值90℃的时间,通过室内试验模拟结合面温度提高后心墙连续两层铺筑的情况,分别研究了结合面温度在90℃、100℃、110℃情况下沥青混凝土的压实性和变形情况,并进行了现场试验论证。室内试验结果表明:心墙沥青混凝土结合面温度降至100℃时,上层沥青混凝土的孔隙率为2.88%,下层沥青混凝土的最大侧向应变值为2.78%;结合面温度为110℃时,上层沥青混凝土的孔隙率为3.85%,下层沥青混凝土的最大侧向应变值为4.00%。现场试验结果表明:结合面温度为100℃时的上层沥青混凝土孔隙率和渗透系数均满足规范要求。因此,沥青混凝土心墙连续多层碾压时,结合面温度提高至100℃的施工质量可以得到保证。     

Intergranular oxidation of silicon in 20Cr-25Ni niobium-stabilized stainless steel at 1140–1230 K

The kinetics of intergranular oxidation of silicon in a 20Cr-25Ni Nb-stabilized stainless steel are reported, at temperatures in the range 1140–1230 K, in CO₂ at 40 bar pressure. The depth of attack increased parabolically with respect to time, with an activation energy of 335±30 kJ/mol. The mechanism of growth is discussed in terms of classical internal-oxidation theories, and an alternative explanation based on an available-space theory is developed. The internal oxidation rates in a number of different alloys are compared with diffusivities of metals in the base alloy. It is proposed that intergranular oxidation in the 20–25 Nb steel is controlled by the rate of outward diffusion of iron or chromium in the alloy.     

Physical and mechanical properties of sandstone containing a single fissure after exposure to high temperatures

In order to investigate the physical and mechanical properties of sandstone containing fissures after exposure to high temperatures,fissures with different angles α were prefabricated in the plate sandstone samples,and the processed samples were then heated at 5 different temperatures.Indoor uniaxial compression was conducted to analyze the change rules of physical properties of sandstone after exposure to high temperature,and the deformation,strength and failure characteristics of sandstone containing fissures.The results show that,with increasing temperature,the volume of sandstone increases gradually while the quality and density decrease gradually,and the color of sandstone remains basically unchanged while the brightness increases markedly when the temperature is higher than 585 ℃;the peak strength of sandstone containing fissures first decreases then increases when the temperature is between 25℃and 400℃.The peak strain of sandstone containing fissures increases gradually while the average modulus decreases gradually with increasing temperature,and the mechanical properties of sandstone show obvious deterioration after 400 ℃.The peak strain of sandstone containing fissures increases gradually while the average modulus decreases gradually with increasing temperature;with increasing angle αof the fissure,the evolution characteristics of the macro-mechanical parameters of sandstone are closely related to the their own mechanical properties.When the temperature is 800 ℃,the correlation between the peak strength and average modulus of sandstone and the angle α of the fissure is obviously weakened.The failure modes of sandstone containing fissures after high temperature exposure are of three different kinds including:tensile crack failure,tensile and shear cracks mixed failure,and shear crack failure.Tensile and shear crack mixed failure occur mainly at low temperatures and small angles;tensile crack failure occurs at high temperatures and large angles.     

钢曲杆在高温（火灾）下的力学特征数值分析

高温(火灾)环境下钢曲杆的受力和变形将会产生较大变化,对结构的力学特征影响较大。本文根据结构稳定理论和热力学原理,应用有限元分析方法,结合三种不同工况,分别探讨了高温(火灾)环境下不同支座形式、杆截面形式等因素对钢曲杆力学特征的影响,并对三种工况下钢曲杆力学特征进行了数值分析与对比,得出了H型钢截面无铰钢曲杆更加符合建筑安全要求的结论,研究成果可为钢曲杆抗火研究提供参考。