不同含水量尾砂的光谱特征与遥感模型

我国尾矿库数量众多，分布广泛，在低含水量条件下，风力作用引起的尾砂扬尘会对周边环境造成污染。而尾矿库表面积大，含水量变化快，传统的含水量监测方法效率低、安全性差、成本高，难以实现尾矿库含水量的大面积、实时、快速的监测。目前，基于光谱特征的遥感模型虽可以较为准确地预测土壤含水量，但矿区尾砂与常规土壤在成分上存在差异性，使得土壤含水量的光谱预测遥感模型可能无法适用于尾矿库含水量的预测。为此，选择辽宁省风水沟尾矿库作为研究区，采集尾砂配置成不同含水量的样品，测试其可见光-近红外光谱，分析不同含水量样品的光谱特征以及含水量与光谱特征之间的关系，建立针对尾砂的含水量遥感预测模型，并应用于辽宁省风水沟尾矿库表面含水量的预测。结果表明：（1）含水量对尾砂的光谱特征有显著影响，二者存在高度的相关性，光谱反射率随含水量增加而下降，且波长越长，含水量对光谱的影响越显著；（2）构建了基于尾砂光谱特征的含水量遥感预测模型，选择Landsat8-OLI传感器的B6和B7波段，定义了比值指数（RTI）、归一化差异指数（NDTI）和差值指数（DTI）3种尾砂光谱指数，并将这3种指数作为输入自变量，使用随机森林方法进行训练以及含水量的建模预测，并与B7波段建立的对数反射率预测模型进行比较。结果表明，光谱指数+随机森林的预测模型效果优于基于B7波段建立的对数反射率模型。（3）使用光谱指数+随机森林的预测模型，通过Landsat8-OLI数据对实地尾矿库提取了含水量的空间分布图，结果表明模型预测的含水量与实测结果之间的决定系数R2达0.798，均方根误差RMSE为0.077，相对分析误差RPD为1.970，平均相对精度ARE为20.1%，在现有技术条件下，达到了较好的预测效果。该研究为变质型铁矿尾矿库含水量的预测提供一种大面积、实时、快速的实用方法。     

基于吸力量测确定膨胀土活动带和裂隙深度

采用M itchell公式和裂隙扩展深度方程两种吸力法确定安康地区膨胀土大气影响深度和裂隙开展深度。其一通过对安康地区两处天然边坡开挖观测井,利用张力计进行不同深度处吸力值的现场量测,根据M itchell提出公式计算大气影响深度;其二根据非饱和土抗拉强度公式,建立膨胀土裂隙扩展深度方程,利用基质吸力量测结果求其理论解。结果表明,安康地区膨胀土吸力变化曲线随深度增加变幅减小,呈“波浪式”推移。M itchell公式确定安康地区膨胀土的大气影响深度为3.35m以内,裂隙深度方程确定裂隙开展深度为3.06³.14m。利用M itchell公式计算大气影响深度与膨胀土断裂理论公式确定的裂隙开展深度结果接近。     

Dehydration kinetics of salmon and trout fillets using ultrasonic vacuum drying as a novel technique

In this study, a novel ultrasonic vacuum (USV) drying technique was used to shorten the drying time of fish fillets. For this purpose, ultrasonic treatment and vacuum-drying were simultaneously performed to dehydrate salmon and trout fillets at 55 °C, 65 °C, and 75 °C. In addition, the USV technique was compared with vacuum-drying and oven-drying techniques. The dehydration kinetics of the fillets was successfully described by seven thin-layer drying models with R² range between 0.944 and 1.000. Depending on drying temperatures and fish species, the drying times could be shortened using the USV technique between 7.4% and 27.4% compared with vacuum-drying. The highest effective moisture diffusivity was determined in the fillets dried with the USV technique and they increased with increasing drying temperatures. Ultrasonic treatment accelerated the vacuum drying process for the fillets; therefore, this technique could be used to improve the efficiency of vacuum-drying for the fillets.     

One-step measurements of powder resistivity as a function of relative humidity and its effect on charging

A new one-step technique to measure the effect of ambient humidity on powder resistivity has been previously presented. In this article, we provide more experimental data obtained with five different powders. One-step measurements and traditional multi-step measurements were performed. Also, additional measurements were performed using standard resistivity cell. Results were compared and it could be concluded that the new technique provided meaningful results although significant hysteresis was observed during humidification and drying cycles. Finally, charging of the powder was also measured and it was noticed that it decreases with decreasing resistivity and increasing humidity.     

偶氮苯基型离子液体溶液对空气中湿度的变色响应

Room temperature ionic liquids (ILs) that can exhibit a colorimetric response to moisture in the air are rarely reported in the literature. In this study, an azophenolic IL solution exhibited a spontaneous a colorimetric response, driven by the formation of hydrogen bonding between the [PhN＝NPhO] anion and moisture in the air. This phenomenon was clearly understood using ultraviolet-visible (UV-Vis) absorption spectroscopy, nuclear magnetic resonance (NMR) spectra, experimental data, and theoretical calculations. Specifically, in the UV-Vis absorption spectra, absorption around 455 nm decreased, while the band around 343 nm increased in the IL CHCl₃ solution as time progressed; this was accompanied by a color change from orange to faint yellow. This spontaneous, self-responsive process was further observed using ¹H NMR data. When the IL solution was placed with sufficient time, all the ¹H NMR peaks of the azophenolic anion shifted downfield, but no new signals appeared in the upfield region. The reason for this was easily identified as the stimuli in the air, such as CO₂ and moisture. When pure CO₂ was bubbled through the IL CHCl₃ solution, the solution color changed from its original orange to light orange, but could not change further to faint yellow, which ruled out CO₂ gas as a stimulus. When a small amount of water was gradually added to the IL solution (MeCN solvent), the absorption band around 474 nm decreased, coupled with an increase in the absorption band around 347 nm. This was accompanied by a color change from orange to faint yellow, which was almost identical to the self-responsive process in CHCl₃ and CCl₄. Moreover, two cuvettes of IL CHCl₃ solution were placed under relative humidities of 28% and 100%, respectively; the IL CHCl₃ solution required a much longer time to exhibit a complete color change from orange to faint yellow under a lower relative humidity, demonstrating that moisture is the most likely stimulus triggering the self-responsive color change of the IL solution. As revealed by the Gaussian 09 program at the B3LYP/6-31++G(p, d) level, the distance between the oxygen atom on the azophenolic anion and the hydrogen atom on the H₂O molecule was 0.174 nm, and the corresponding angle was 171.12°. Furthermore, the atomic dipole moment corrected Hirshfeld (ADCH) charge of the oxygen atom on the azophenolic anion was −0.52, and it increased to −0.62 after the azophenolic anion interacted with the H₂O. Reduced density gradient analysis revealed that the spike corresponding to O∙∙∙H―O for the IL-H₂O complex was located at around −0.04 a.u.. All the above data indicate that the presence of hydrogen bonding rendered the IL solution responsive to the moisture stimulus, and this response was accompanied by a color change that was visible to the naked eye. To the best of our knowledge, this is the first demonstration of a colorimetric change in an IL solution in response to moisture. We hope this work can help us to gain insight into some seemingly abnormal phenomena that occur during the research process.     

太赫兹光谱技术用于干旱胁迫下大豆冠层含水量检测研究

近年来水资源短缺问题日益严重，部分地区由于农业灌溉用水不足导致庄稼减产农民利益受损。大豆是一种需水量较大的农作物，一旦水分亏缺将直接影响大豆植株的形态和生长发育，从而造成大豆品质降低和产量减少。大豆叶片的水分状况可真实地反映植株水分受土壤水分亏缺的影响程度，因此，大豆冠层叶片水分含量的快速获取成为一种需要。太赫兹辐射在水中的强烈衰减使其成为一种非常灵敏的非接触式探针，可以快速、无损地检测叶片含水量。因此基于太赫兹光谱这一新技术进行大豆冠层叶片含水量的检测研究，用于实时监测田间大豆的健康状况。实验选用中黄13号大豆进行栽培，为尽可能模拟田间不同程度的干旱胁迫状况，将开花期大豆进行5个不同梯度：正常供水、轻度干旱胁迫、中度干旱胁迫、重度干旱胁迫、严重干旱胁迫(分别占田间最大持水量的80%，65%，50%，35%，20%)的水分灌溉，每个梯度设置3个重复。利用人工称重法与便携式土壤水分速测仪结合将土壤含水量调控到各水分梯度要求。然后，将实验大豆植株运回实验室并利用透射式太赫兹时域光谱仪进行样本扫描，每个梯度采集18片冠层叶片，共90个样本，以2∶1的比例分为校正集和预测集。在获取各样本时域光谱数据后，根据Dorney和Duvillaret提出的模型进行了光学参数的提取，得到各样本的吸收系数谱以及折射率谱。定性分析了太赫兹时域光谱、吸收系数、折射率随水分胁迫程度不同的变化情况。实验发现：随着水分胁迫程度的降低，时域光谱的峰值呈不断衰减趋势，且均低于空白参考峰值，同时有明显的时间延迟。吸收系数值随干旱胁迫程度的加剧逐渐降低；折射率值同样随干旱胁迫程度的加剧逐渐降低。并利用偏最小二乘(PLS)和多元线性回归(MLR)方法定量研究了时域光谱、吸收系数、折射率光谱数据与叶片含水率的相关关系。结果表明，太赫兹波对大豆叶片水分差异十分敏感，基于时域光谱最大值和最小值的MLR预测精度最高，预测集相关性(r_p)达-0.939 3，均方根误差(RMSEP)为0.049 5。研究表明太赫兹光谱技术应用于大豆冠层叶片含水量观测具有良好的可行性，为开展大豆冠层含水量信息快速获取，实现科学节水管理与灌溉决策提供了新的检测手段和实验依据。     

基于高光谱技术的土壤水分无损检测

利用高光谱成像仪(光谱范围400～1 000 nm)对土壤含水率进行了无损检测。比较了208个土样不同天数下土壤含水率与光谱变化、不同质量含水量光谱的差异；对比分析了不同光谱预处理方法、不同方法提取特征波长、采用多元线性回归(multiple linear regression，MLR)、主成分回归(principal component regression，PCR)与偏最小二乘回归(partial least squares regression，PLSR)建模，优选出最佳模型。结果表明：光谱曲线的反射率随着土壤含水率的增加而减小。当超过田间持水率时，光谱曲线的反射率会随着土壤含水率的增加而增大。对比分析了不同预处理方法，近红外波段优选出单位向量归一化预处理方法。采用无信息变量消除法(UVE)、竞争自适应加权采样(CARS)、β系数法、连续投影算法(SPA)方法提取特征波长为49，30，5和7。为了减少数据冗余，对UVE与CARS提取的特征波长进一步采用SPA方法进行特征提取，UVE+SPA，CARS+SPA提取特征波长数分别为5和8个。在此基础上，利用MLR，PCR和PLSR方法对400～1 000 nm范围的特征波长建立模型，对比分析不同建模效果，优选出β系数提取的特征波长的MLR模型。最优的特征波长为411，440，622，713和790 nm，最优模型的预测相关系数R_p=0.979，预测均方根误差RMSEP为0.763。因此，今后可采用不同波段对土壤含水率进行定量分析。     

Preparation of safe water–lipid mixed electrolytes for application in ion capacitor

Aqueous electrolytes are safe, economic, and environmentally friendly. However, they have a narrow potential window. On the other hand, organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive. In this study, we prepared water–PEG–lipid ternary electrolytes(TEs). To combine the advantages of water, polyethylene glycol(PEG) and propylene carbonate(PC). The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC. Using these TEs, a lithium manganate–active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg, based on the total active electrode material(current density of 3.3 m A/cm~2). This value was significantly higher than that achieved using an aqueous electrolyte, thereby rationalizing the higher energy density.     

绿肥对华北潮土土壤可溶性有机物的影响

在华北潮土上种植不同绿肥,于绿肥翻压前原位采集其地上部及土壤样品,进行56d的绿肥翻压模拟试验。设毛叶苕子(Vicia villosa Roth.)、二月兰(Orychophragmus Violaceus L.)、黑麦(Secale cereale L.)三个绿肥处理和无绿肥对照处理,分析培养过程中土壤可溶性有机物(DOM)组分及其紫外-可见光谱参数的变化,以探究绿肥对土壤DOM的影响。种植和翻压绿肥增加土壤可溶性有机碳(DOC)、总有机酸碳(TOAs)和总碳水化合物碳(TCs)含量,三者的变化趋势一致,各处理均在培养第1d上升至峰值后迅速下降。毛叶苕子提高DOC和TOAs的效果最好,最高比对照增加114.01%(培养第1d)和109.10%(培养第14d)。黑麦提高TCs的效果最好,最高比对照增加323.18%(培养第42d)。种植和翻压绿肥增加土壤可溶性有机氮(DON)含量,与DOC变化趋势不同,各处理在培养第1d上升后迅速下降一段时间后又迅速上升。毛叶苕子提高DON的效果最好,最高比对照增加305.83%(培养第42d)。绿肥增加了SUVA_(254),SUVA_(260),SUVA_(272),SUVA_(280),SAUC_(240-400),降低了A_(250)/A_(365)和A_(240)/A_(420)。紫外-可见光谱参数的主成分分析显示SUVA_(254),SUVA_(260),SUVA_(272),SUVA_(280)间有很高正相关性,A_(250)/A_(365)和A_(240)/A_(420)间亦有很高正相关性,SAUC_(240-400)是这些参数中表征DOM性质的关键因子。综上结果表明,种植翻压绿肥增加了土壤DOM含量,提高了土壤DOM的芳香性、疏水性、腐殖化程度、平均分子量,增加了土壤DOM的稳定性。     

太赫兹时域光谱技术的变压器油低水含量检测

变压器的维护至关重要。变压器油中水含量的检测是变压器维护中很重要的一部分。水在太赫兹频段独特的分子键振动模式使其对太赫兹波具有强烈的吸收性。利用太赫兹时域光谱技术对变压器油进行水含量检测，获得了不同水含量变压器油的吸收系数和折射率，结合相关理论模型对获得的参数进行了分析验证。试验结果表明，变压器油的吸收系数和折射率与水含量呈线性关系。