荧光光谱法鉴别海面溢油源的研究进展

本文以大量的研究成果介绍了荧光光谱技术在鉴别海面溢油源中的应用和进展。根据普通荧光光谱、同步扫描光谱、可变角同步扫描光谱和总荧光光谱等不同荧光光谱信息特等，论述了荧光光谱的三维特性及维特性及其在溢油鉴别中的应用。同时，结合低温荧光法、磷光光谱法、导数荧光光谱法等辅助方法和技术，介绍了国内外荧光光谱法鉴别海面溢油的新进展和新成果。     

两次金汞齐-冷原子荧光光谱法测定大气中的痕量气态总汞

建立了两次金汞齐-冷原子荧光光谱法(CVAFS)测定大气中痕量气态总汞(TGM)的方法。研究表明:本方法的绝对检出限为2 pg;当以0.2~0.4 L·min-1 采样速度,采集12~48 h时,采样效率> 99%,精密度为9.63%;样品经2次循环加热分析,热解吸效率> 99%。这种分析方法还可以运用到其他环境样品痕量汞的测定。     

A spectral power analysis of driving behavior changes during the transition from nondistraction to distraction

Objective: This article investigated and compared frequency domain and time domain characteristics of drivers' behaviors before and after the start of distracted driving.

Method: Data from an existing naturalistic driving study were used. Fast Fourier transform (FFT) was applied for the frequency domain analysis to explore drivers' behavior pattern changes between nondistracted (prestarting of visual–manual task) and distracted (poststarting of visual–manual task) driving periods. Average relative spectral power in a low frequency range (0–0.5 Hz) and the standard deviation in a 10-s time window of vehicle control variables (i.e., lane offset, yaw rate, and acceleration) were calculated and further compared. Sensitivity analyses were also applied to examine the reliability of the time and frequency domain analyses.

Results: Results of the mixed model analyses from the time and frequency domain analyses all showed significant degradation in lateral control performance after engaging in visual–manual tasks while driving. Results of the sensitivity analyses suggested that the frequency domain analysis was less sensitive to the frequency bandwidth, whereas the time domain analysis was more sensitive to the time intervals selected for variation calculations. Different time interval selections can result in significantly different standard deviation values, whereas average spectral power analysis on yaw rate in both low and high frequency bandwidths showed consistent results, that higher variation values were observed during distracted driving when compared to nondistracted driving.

Conclusions: This study suggests that driver state detection needs to consider the behavior changes during the prestarting periods, instead of only focusing on periods with physical presence of distraction, such as cell phone use. Lateral control measures can be a better indicator of distraction detection than longitudinal controls. In addition, frequency domain analyses proved to be a more robust and consistent method in assessing driving performance compared to time domain analyses.     

Clove as antioxidant additive in diesel–biodiesel fuel blends in diesel engines

Increased NOx emission from usage of biodiesel is a burning issue to be dealt with. Many techniques have been adopted to reduce NOx emissions from diesel engines. The present experimental study deals with the analysis of performance and emission characteristics of Cotton Seed oil biodiesel with the addition of natural antioxidant extract of clove. FTIR analysis characterized the antioxidant by the presence of hydroxyl groups denoted by the corresponding wave number. The oxidation stability of the test samples was determined in terms of induction period by means of Rancimat test. The induction periods of the test fuel samples B100, B20, B20+CL1000, and B20+CL2000 were found to be 2.20 h, 2.73 h, 10.19 h, and 11.12 h, respectively. Thus, the addition of Clove antioxidant increased the oxidation stability of the biodiesel. Results show that the addition of antioxidant to biodiesel blend has increased the Brake Thermal Efficiency to a maximum of 4.71% and decreased the Brake Specific Fuel Consumption to a maximum of 6.25% at full-load conditions compared to Cotton Seed biodiesel blend. The addition of Clove extract antioxidant at a concentration of 1000 ppm and 2000 ppm decreases the NOx emission by 23.03% and 26.7%, respectively, at full-load conditions. However, CO emissions increased by 1.12% and 4.49% with the addition of CL1000 and CL2000 to B20, respectively. Similarly, HC emissions increased by 4.19% and 7.35% by the addition of CL1000 and CL2000 to B20, respectively. The increases in smoke with the addition of CL1000 and CL2000 to B20 were 42.48% and 47.71%, respectively.     

二龙湖表层水体有色溶解有机物的光学特性及来源

CDOM（colored dissolved organic material,有色溶解有机物）的光学特性可反映水体中内源物质与外源物质的比例,为了解二龙湖受到上游来水所含污染物的影响,利用荧光区域一体化技术和荧光指数分析水体中CDOM的荧光特性,进而判定水体污染状况,并结合CDOM荧光组分与水质参数之间的关系,探讨了不同季节二龙湖水体中CDOM光学特性在时空分布上的差异性以及CDOM的组成与来源.结果表明:①水相中CDOM表现出明显的季节性差异.其中,光谱斜率S_g（275~295 nm）和E_{250 nm:365 nm}〔a_CDOM（250）/a_CDOM（365）〕均表现为丰水期>平水期>枯水期,SUVA_{254 nm}表现为枯水期>平水期>丰水期.②水体中的荧光组分以外源组分R3（富里酸类物质）和R5（腐殖酸类物质）为主,在枯水期、丰水期和平水期分别占总荧光强度的70.0%、60.4%和51.3%.③在丰水期、枯水期、平水期,FI_{310 nm}平均值均大于0.8,FI_{370 nm}平均值均小于1.4,表明在3个水文期,微生物活动带来的内源CDOM在二龙湖南部较为明显.④ρ（DOC）（dissolved organic carbon,溶解性有机碳）与CDOM的荧光组分R2（色氨酸类组分）、R4（可溶性微生物副产物组分）和R5（腐殖酸类组分）均具有较好的相关性,相关系数（R）分别为0.71、0.80、0.73,表明DOC主要源于微生物代谢的可溶性副产物及浮游植物的降解.研究显示:水体中CDOM主要组成为内源的色氨酸与微生物蛋白质类副产物以及外源的富里酸类与腐殖酸类有机物;同时,由于冰冻、降水、生活污水排放、农业废水和水生植物等因素,导致湖泊中的CDOM的组分与来源十分复杂.      

IWO-PSO-SVR算法在甲烷检测中的应用

提出一种入侵杂草算法改进的粒子群算法（IWO-PSO）用于支持向量机（SVR）算法来快速实时检测甲烷气体浓度系统,气体红外激光差分吸收法检测系统基于甲烷气体分子在1650nm处泛频光谱吸收带,结合可调谐二极管吸收光谱（TDLAS）与波长调制光谱（WMS）.选择半导体激光器瞬时输出光功率变化范围5.0~10.6mW,瞬时波长变化范围1650~1651nm,瞬时调谐频率范围0.0048~0.0115nm/mA;采集山东淄博某农场2019年3月份全天气体样本,随机抽取15组样本作为训练集,建立以光谱峰面积作为输入值与气体浓度作为输出值的IWO-PSO-SVR、SVR、PSO-SVR和PSO-BP定量分析模型,对测试集4种浓度的甲烷分别进行预测;结果表明,通过IWO-PSO-SVR定量分析模型效果最佳,4种甲烷浓度预测值与真实值相对偏差分别为0.115%、0.109%、0.131%、0.120%,均低于0.0014;相关系数分别为0.9987、0.9966、0.9899、0.9975均高于0.98;预测时间分别为1.35、1.54、1.35和1.33s,模型经过1000次训练对气体的检测精度为10^-5,与同类别检测系统相比,具有很强的理论研究价值和工程应用价值.     

一种基于离心机试验辨识惯导平台误差系数的方法

针对离心机试验中惯导平台误差系数辨识问题,提出了一种基于谐波分析辨识误差系数的方法。首先,根据惯性器件误差模型推导了离心机试验下陀螺和加速度计的输出方程,其输出由各阶谐波分量构成。然后通过傅里叶分析得到各项谐波的幅值。最后根据谐波幅值与各项误差系数之间的关系反解得到各项误差系数。仿真结果验证了方法的有效性。     

流动海水环境中人工破损有机涂层的劣化过程研究

目的研究流动海水环境中人工破损有机涂层的劣化过程。方法使用电化学阻抗谱(EIS)技术对比研究流动海水与静止海水环境中破损涂层的劣化行为,跟踪观察涂层宏观形貌演变。结果根据EIS响应特征,发现流动海水中的人工破损有机涂层劣化更快,且在浸泡后期流动海水中破损涂层没有形成扩散阻抗。根据涂层宏观形貌发展,发现静止海水中涂层仅围绕破损处出现了面积较小的锈点和鼓泡,而流动海水中涂层因劣化而产生的锈点和鼓泡面积更大且大量分布在整个涂层表面。结论当人工破损有机涂层在流动海水和静止海水环境的浸泡过程中,涂层劣化首先从人工破损处开始。破损处成为局部腐蚀反应主要的阳极区,破损处周围的区域和涂层内在缺陷处成为扩展腐蚀反应的阴极区。流动海水中涂层的腐蚀产物累积与脱落更加频繁,导致涂层劣化速度加快和基体金属腐蚀加剧。     

吸水性还原性材料对煤自燃影响的实验研究

为了解决吸水性盐和还原性材料仅依靠其单一特性抑制煤自燃而抑制效果并不理想的问题,提出了利用羟甲基磺酸钠的吸水性和还原性来抑制煤自燃。将原煤-20%羟甲基磺酸钠通过对比原煤、原煤-20%MgCl2和原煤-20%VC,利用程序升温实验和FTIR测试来研究其抑制煤自燃的效果。研究结果表明:3种溶液处理煤均在一定程度上抑制了煤自燃,其中,20%羟甲基磺酸钠溶液对抑制煤低温氧化的效果最好,经过其处理的煤样表观活化能最大,同时,依靠其还原性很好地保护了煤中的亚甲基和羟基不被破坏,抑制煤自燃效果明显优于20%MgCl2溶液和20%VC溶液。     

一种高效测试污泥可生物降解性的实验方法研究

污泥的可生物降解性能由其有机组分的生物可及度和组分分子的复杂度共同决定。通过采用化学分级提取方法研究污泥组分的生物可及度,使用不同强度的提取溶液分离出4种化学可及度不同的提取组分,同时结合三维荧光光谱法对各组分中有机物质的复杂度进行分析。分析结果表明:组分的化学可及度与其生物可及度之间存在正相关关系;生物可及度较高,其成分有机物分子结构简单的组分SPOM(soluble particulate organic matter,SPOM)与REOM(readily extractible organic matter,REOM)在厌氧消化过程中降解率较高,分别为59.2%与46.3%的COD;而生物可及度低,组成复杂的组分SEOM(slowly extractible organic matter,SEOM)与PEOM(poorly extractible organic matter,PEOM)的生物降解率分别只有18.4%和5.8%的COD。