乙基紫共振瑞利散射法测定碘酸钾

在磷酸介质中,碘酸钾与碘化钾反应生成I-^3配阴离子,它可进一步与乙基紫形成离子缔合物,此时不仅能引起吸收光谱的变化,而且能导致共振瑞利散射（RRS）的显著增强并产生新的RRS光谱,其最大散射波长位于319nm．在一定条件下,其散射强度△I与碘酸钾浓度成正比,其线性范围在2．33×10^-3～3．00μg·mL^-1之间,方法具有极高的灵敏度,对碘酸钾的检出限为0．70ng·mL^-1,也具有良好的选择性,可用于食盐中碘酸钾的直接测定。     

共轭传热室内自然对流数值模拟研究

研究建筑围护结构传热与流体流动综合作用下室内自然对流数值模拟，建立了一套同时在固体一流体区域整体求解连续性方程、动量方程和能量方程的数值模拟方法。具体分析了瑞利数变化范围为10^4到10^6时建筑围护结构传热对室内自然对流的影响。数值预测结果表明：该方法能够真实反映室内自然对流问题。为室内自然对流问题数值模拟提供了一种实用有效的方法。     

发动机进气管中压力波动和气体运动的研究

在发火运转和不同转速，负荷下，测量了单缸柴油机进气管气流参数，并分析研究了这些参数的变化规律。此外，还得在进气马赫数Z不是转速的单值函数；在定转速而负荷不同时，它不是常数。     

延边半细毛羊心电图正常值的测定

本实验通过４９例健康延边半细毛羊心电图的描记，初步测定出其正常值。测定的结果表明；心电图为窦性心律，平均心率为１０２次／分；Ｐ波振幅平均为０．０５８ｍＶ，眼限平均为０．０３７秒；Ｐ—Ｒ间期平均为０．１１６秒；ＱＲＳ波群里多种波型，其中以ｑＲ、Ｑｒ、ｑＲｓ和ｒＳ型为最多，时限平均为０．０３９秒；Ｓ—Ｔ段平稳，时限平均为０．１９６秒；Ｔ波振幅平均为０．０８２ｍＶ，时限平均为０．０６５秒；Ｑ—Ｔ间期平均为０．２９５秒。此测定，为心电图应用于诊断延边半细毛羊心脏疾病提供了一定的科学依据。     

电磁波吸收功能木基胶合板的制备与性能北大核心

以纳米炭黑为电磁损耗材料对木质基板进行表面电磁改性,以此为基础设计并制备连续渐变阻抗结构吸波胶合板,研究了电磁改性对木质基板微观形貌以及阻抗的影响,测试了胶合板吸波性能及其他理化性能。结果表明:纳米炭黑在木质基板表面形成均匀、连续、光滑的电磁改性涂层;胶合板对1.8~5GHz电磁波反射率小于-7dB,胶合板层数增加,反射吸收峰向低频方向移动,增加吸收层层数可拓宽吸波频段;胶合板厚度一定时,减少吸收层层数或增加匹配层层数,反射吸收峰强度减弱;胶合强度、静曲强度等其他理化性能均满足标准要求。开发的吸波胶合板在电磁辐射防护领域具有广阔应用前景。     

潜浮式船型桁架结构深海养殖网箱避浪性能研究

深海网箱作为现代海洋渔业拓展外海养殖空间的重要养殖装备，其布设环境一般较近海更为复杂恶劣，对于保障其安全性和稳定性提出了更高的要求。本研究针对一种单点系泊潜浮式船型桁架网箱开展了模型比尺为1︰40的波浪流水池试验，重点围绕该网箱在不同吃水深度受波浪作用的系泊受力、升沉、纵摇和横摇等水动力学特性进行了比较分析。试验结果显示，波高为7.5~12.5 cm时(原型3~5 m)，网箱漂浮状态即可以满足养殖需求，其系泊力及运动响应均较小，具备较高的安全性和稳定性；恶劣海况时，即本试验中波高为15.0和17.5 cm (原型6 m和7 m)，通过整体下潜的方式网箱具有良好的避浪性能，其中，系泊力减幅达70%以上，升沉、纵摇和横摇等运动分量减幅也达20%~60%；波流试验中，海流对网箱避浪性能存在一定的影响，但总体上仍然具有较好的避浪效果。研究结果可为单点系泊潜浮式深海网箱的安全运行与日常管理提供理论依据和数据参考。     

Evaluating the soil evaporation loss rate in a gravel-sand mulching environment based on stable isotopes data

In order to cope with drought and water shortages, the working people in the arid areas of Northwest China have developed a drought-resistant planting method, namely, gravel-sand mulching, after long-term agricultural practices. To understand the effects of gravel-sand mulching on soil water evaporation, we selected Baifeng peach (Amygdalus persica L.) orchards in Northwest China as the experimental field in 2021. Based on continuously collected soil water stable isotopes data, we evaluated the soil evaporation loss rate in a gravel-sand mulching environment using the line-conditioned excess (lc-excess) coupled Rayleigh fractionation model and Craig-Gordon model. The results show that the average soil water content in the plots with gravel-sand mulching is 1.86% higher than that without gravel-sand mulching. The monthly variation of the soil water content is smaller in the plots with gravel-sand mulching than that without gravel-sand mulching. Moreover, the average lc-excess value in the plots without gravel-sand mulching is smaller. In addition, the soil evaporation loss rate in the plots with gravel-sand mulching is lower than that in the plots without gravel-sand mulching. The lc-excess value was negative for both the plots with and without gravel-sand mulching, and it has good correlation with relative humidity, average temperature, input water content, and soil water content. The effect of gravel-sand mulching on soil evaporation is most prominent in August. Compared with the evaporation data of similar environments in the literature, the lc-excess coupled Rayleigh fractionation model is better. Stable isotopes evidence shows that gravel-sand mulching can effectively reduce soil water evaporation, which provides a theoretical basis for agricultural water management and optimization of water-saving methods in arid areas.