Recognition of Vehicles Entering Expressway Service Areas and Estimation of Dwell Time Using ETC Data

To scientifically and effectively evaluate the service capacity of expressway service areas (ESAs) and improve the management level of ESAs, we propose a method for the recognition of vehicles entering ESAs (VeESAs) and estimation of vehicle dwell times using electronic toll collection (ETC) data. First, the ETC data and their advantages are described in detail, and then the cleaning rules are designed according to the characteristics of the ETC data. Second, we established feature engineering according to the characteristics of VeESA and proposed the XGBoost-based VeESA recognition (VR-XGBoost) model. Studied the driving rules in depth, we constructed a kinematics-based vehicle dwell time estimation (K-VDTE) model. The field validation in Part A/B of Yangli ESA using real ETC transaction data demonstrates that the effectiveness of our proposal outperforms the current state-of-the-art. Specifically, in Part A and Part B, the recognition accuracies of VR-XGBoost are 95.9% and 97.4%, respectively, the mean absolute errors (MAEs) of dwell time are 52 and 14 s, respectively, and the root mean square errors (RMSEs) are 69 and 22 s, respectively. In addition, the confidence level of controlling the MAE of dwell time within 2 min is more than 97%. This work can effectively recognize the VeESA and accurately estimate the dwell time, which can provide a reference idea and theoretical basis for the service capacity evaluation and layout optimization of the ESA.     

Experimental and Theoretical Studies of the Optical Properties of the Schiff Bases and Their Materials Obtained from o-Phenylenediamine

Two macrocyclic Schiff bases derived from o-phenylenediamine and 2-hydroxy-5-methylisophthalaldehyde L1 or 2-hydroxy-5-tert-butyl-1,3-benzenedicarboxaldehyde L2, respectively, were obtained and characterized by X-ray crystallography and spectroscopy (UV-vis, fluorescence and IR). X-ray crystal structure determination and DFT calculations for compounds confirmed their geometry in solution and in the solid phase. Moreover, intermolecular interactions in the crystal structure of L1 and L2 were analyzed using 3D Hirshfeld surfaces and the related 2D fingerprint plots. The 3D Hirschfeld analyses show that the most numerous interactions were found between hydrogen atoms. A considerable number of such interactions are justified by the presence of bulk tert-butyl groups in L2. The luminescence of L1 and L2 in various solvents and in the solid state was studied. In general, the quantum efficiency between 0.14 and 0.70 was noted. The increase in the quantum efficiency with the solvent polarity in the case of L1 was observed (λ_ex = 350 nm). For L2, this trend is similar, except for the chloroform. In the solid state, emission was registered at 552 nm and 561 nm (λ_ex = 350 nm) for L1 and L2, respectively. Thin layers of the studied compounds were deposited on Si(111) by the spin coating method or by thermal vapor deposition and studied by scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), spectroscopic ellipsometry and fluorescence spectroscopy. The ellipsometric analysis of thin materials obtained by thermal vapor deposition showed that the band-gap energy was 3.45 ± 0.02 eV (359 ± 2 nm) and 3.29 ± 0.02 eV (377 ± 2 nm) for L1/Si and L2/Si samples, respectively. Furthermore, the materials of the L1/Si and L2/Si exhibited broad emission. This feature can allow for using these compounds in LED diodes.     

Scattering of Tollmien-Schlichting waves by localized roughness in transonic boundary layers

The laminar-turbulent transition in boundary-layer flows is often affected by wall imperfections, because the latter may interact with either the freestream perturbations or the oncoming boundary-layer instability modes, leading to a modification of the accumulation of the normal modes. The present paper particularly focuses on the latter mechanism in a transonic boundary layer, namely, the effect of a two-dimensional(2 D) roughness element on the oncoming Tollmien-Schlichting(T-S) modes when th...     

Falkner-Skan方程的近似解析解

研究了粘性流体绕流楔型物体的Falkner-Skan边界层方程求解问题.利用Adomian拆分方法,通过引入Crocco变量变换将无穷区间的边界值问题转为初值问题并利用Padé逼近技巧确定初值,给出了一种有效的解析分解方法.进一步,本文设计了一种数值解法,将本文得到的近似解析解及数值结果与早期研究者Hartree等人的结果进行了比较,证明了本文提出的解法的有效性和可靠性.     

新型掺碳二氧化硅-薄膜体声波谐振器结构及其仿真验证

一定厚度的低声阻抗支撑层可以在薄膜体声波谐振器(FBAR)与衬底之间形成声学隔离层,防止声波泄漏到衬底当中。掺碳二氧化硅(CDO)是一种低声阻抗材料,对FBAR具有较好的温度补偿效果,可以作为FBAR与衬底之间的声学隔离层,从而构成一种新型的CDO-FBAR。为了分析CDO-FBAR与通孔型FBAR相比性能是否退化,以及CDO声学隔离层所需厚度,采用多物理场耦合仿真软件分析了CDO-FBAR和通孔型FBAR的谐振频率、Q值、有效机电耦合系数和S参数,并提取了CDO-FBAR纵向振动位移。分析结果表明：CDO-FBAR的谐振频率整体向下漂移;CDO声学隔离层导致S参数的寄生干扰;由于声学损耗增加,Q值略有降低,其中并联谐振点处的Q值降幅更大;有效机电耦合系数略有降低;声波传播到声学隔离层中9 m处就完全衰减,即只需要9 m厚的CDO声学隔离层就能在FBAR与衬底之间形成有效的声学隔离。由此,仿真验证了这种新颖的CDO-FBAR结构的可行性。     

Alternative Ecosorbent for the Determination of Trihalomethanes in Aqueous Samples in SPME Mode

A new sorbent material based on modified clay with ionic liquid immobilized into an agarose film was developed as part of this study. It was applied to determine organochlorine pollutants, like disinfection byproducts, through headspace solid-phase microextraction-gas chromatography-electron capture detection (HS-SPME-GC-ECD). The disinfection byproducts determined in this study were used as model molecules because they were volatile compounds, with proven severe effects on human health. Their presence in aquatic environments is in trace concentrations (from pg L⁻¹ to mg L⁻¹). They are classified as emergent pollutants and their determination is a challenge for analytical chemists. The parameters which affected the extraction efficiency, i.e., number and distance between SPME discs, salt concentration, the temperature of extraction, extraction time, and desorption time, were optimized. A wide linear dynamic range of 10–1000 ng mL⁻¹ and coefficients of determination better than 0.997 were achieved. The limits of detection and the limits of quantitation were found in the ranges of (1.7–3.7) ng mL⁻¹ and (5.6–9.9) ng mL⁻¹, respectively. The precision, expressed as relative standard deviation (RSD), was better than 8%. The developed sorbent exhibits good adsorption affinity. The applicability of the proposed methodology for the analysis of trihalomethanes in environmental and water samples showed recoveries in the range of 86–95%. Finally, the newly created method fully complied with the principles of green chemistry. Due to the fact that the sorbent holder was made of agarose, which is a wholly biodegradable material, sorbent clay is a widespread material in nature. Moreover, the reagents intercalated into the montmorillonite are new green solvents, and during the whole procedure, low amounts of organic solvents were used.     

大气光学湍流估算模式及其相似性函数

地表热通量和水汽通量对全球气候变化和大气环流有着重要而广泛的影响,而Monin-Obukhov(M-O)相似性函数在计算近地层热通量和水汽通量的过程中扮演着重要的角色;同时M-O相似性函数是大气光学湍流估算模式中不可或缺的因子。通过对合肥西郊35 m铁塔上气象数据的分析,利用非线性最小二乘法拟合得到了一套全新的M-O相似性函数。将之与前人提出的相似性函数作对比,展现出了较好的一致性。同时,该函数大气光学湍流的估算模式中,估算值与实测值具有较好的吻合度。分析结果表明：在稳定条件和非常不稳定条件下,可以认为温度相似性函数等于湿度相似性函数,在弱不稳定条件下两者不再满足这种相似性。     

固液界面双电荷层结构的一个界面势模型

当液体受限在纳米尺度下时,会呈现出跟宏观尺度下完全不同的输运性质。这些新的性质可以被应用于很多领域,譬如对生物体中体液输运的研究,液体抽运,药物的混合和分离,以及离子和胶体颗粒的选择等领域。为了充分利用这些新性质,需要对纳米液体中最基本的双电荷层结构有深刻认识。文章回顾了传统的泊松—玻尔兹曼方程对双电荷层结构中液体离子分布的计算,指出了其中的不足,并提出一种基于液体电荷保持中性的固液表面势模型。     

熔石英再沉积层结构的纳米级表征和杂质分析

利用原子力显微镜观察熔石英不同蚀刻时间的表面形貌,结合二次离子质谱分析,研究了熔石英的再沉积层结构和杂质分布。结果表明,熔石英表面深度10 nm的再沉积层内存在大量微裂纹和杂质,经蚀刻展开形成nm级划痕和坑点,其分布随着深度增加呈指数衰减。根据nm级划痕密度、宽深比随蚀刻深度变化的规律,估算出再沉积层厚度,估算结果与二次离子质谱测得的杂质嵌入深度基本一致。杂质元素嵌入深度与抛光微裂纹分布特征的关联性表明,杂质很有可能藏匿在抛光微裂纹中。     

薄层色谱-紫外可见分光光度法测定食品中的苏丹红Ⅰ号

建立了测定食品中苏丹红Ⅰ号新方法:薄层色谱-紫外可见分光光度法.方法的线性回归方程为:A=0.00583 0.15105ρ,在0.50～10.0 μg/mL之间苏丹红Ⅰ号的浓度与吸光度之间呈线性关系,相关系数R=0.9992,检出限为0.05 μg/mL.测定结果与国家标准HPLC法对照,令人满意.可用于食品中苏丹红Ⅰ号的测定.