基于CBDNet的被动源面波信号增强

在被动源面波成像中低质量的频谱图会直接导致后续频散曲线的拾取出现较大的不确定性,为了进一步提高被动面波频谱成像图的质量,同时提高频散曲线的拾取的准确性。文章提出了将在原始数据重构得到的虚拟道集上应用CBDNet进行被动源面波信号增强,降低频散成像能量谱中的噪声、增强频散曲线连续性。文中首先通过数值模拟的方式,验证了网络的有效性;然后将其用于北京市广渠门和通州两个地区的实际被动源数据处理中。结果表明,文章提出的网络和被动源面波去噪方法能够很好的解决实际工程中频谱图质量低,频散曲线错位和不连续的问题。In passive-source surface wave imaging, low-quality spectrograms directly lead to significant uncertainties in the subsequent picking of dispersion curves. To further enhance the quality of passive surface wave spectral imaging and improve the accuracy of dispersion curve picking, this study proposes applying CBDNet to virtual shot gathers reconstructed from the raw data. This approach enhances passive-source surface wave signals, reduces noise in the dispersion imaging energy spectrum, and improves the continuity of dispersion curves. First, the effectiveness of the network is validated through numerical simulations;then, it is applied to real passive-source data from two regions in Beijing, Guangqumen and Tongzhou. The results demonstrate that the proposed network and denoising method for passive-source surface waves effectively address the issues of low spectrogram quality, misaligned, and discontinuous dispersion curves in practical engineering applications.

纤维增强覆面木基墙板抗震性能试验研究

通过2片不带墙骨柱、1片带墙骨柱纤维增强覆面木基墙板的低周往复试验,研究了此类玻璃纤维与胶凝材料结合作为覆面层的木基墙板的破坏形态、滞回特性、承载力、变形能力等抗震性能。试验结果表明:墙板的破坏形态为压弯破坏,墙板两端根部出现水平裂缝和斜裂缝,边框或墙骨柱与墙板结合处出现竖向裂缝,较高轴力下墙板出现裂缝早;墙板相对底座产生较大转动,修正得到的墙板滞回曲线顶点水平位移最大值约为实测顶点水平位移最大值的1/5,峰值位移角在1/528～1/445之间;试件峰值承载力较高,达到100kN,能满足抗震设防烈度不大于8度的3层及以下低层居住建筑抗震的承载力需求。

高分子、生物高分子与金属复合物界面结构的表面增强拉曼光谱研究

用表面拉强拉曼散射(SERS)研究了高分子、生物高分子与金属复合物界面的微观结构。由于 SERS仅对金属表面第一层分子有显著的增强效应,因此它是非常有效的界面结构研究工具。

基于FScore指标的技术面因子增强——从基本面增强反转谈起

股票前期的异常表现可能是由投资者情绪过度反应造成的错杀、公司的基本面显著变化等原因造成的。由后者引发的股票理性下跌,未来可能并不会修复。因此,在计算反转因子时,需要在股票涨跌幅中排除基本面变化的因素。本文采用代理变量FScore来衡量基本面变化导致的收益率,FScore从公司的流动性、财务杠杆、运营效率等多个维度描述了公司的基本面状况,与股票价格呈现正相关的关系。采用反转和双重分组,体现了基本面因素对反转的修正。从实证结果来看,高基本面质量同时前期表现较差的“Loser+High”组合表现最好,基本面较差且前期涨幅较大的股票组合“Winner+Low”组合历史表现最差,组合之间呈现出明显的单调性特征。与原始的反转相比,基本面增强反转的历史表现明显更加优异。本研究仿造基本面增强反转的思路,构建了基本面增强波动率,结果发现相比于原始波动率,经过基本面增强的波动率因子也具有更强的选股能力。

骨巨细胞瘤诊断中增强扫描CT值的应用分析

目的对应用增强扫描CT技术对患有骨巨细胞瘤疾病的患者实施病情诊断的临床价值进行研究。方法选择我院收治的术后确诊为骨巨细胞瘤疾病和非骨巨细胞瘤疾病的患者各53例,分别定义为研究组和对照组。采用增强CT技术对两组研究对象在治疗前实施病情诊断,对比两组增强后CT值和CT值增加值两项指标。结果研究组研究对象的增强后CT值和CT值增加值水平明显高于对照组,组间数据对应比较差异显著(P<0.05)。结论罹患骨巨细胞瘤疾病的患者的增强扫面CT值升高,可作为依据。

LTE-Advanced系统小基站的增强技术研究

小基站已成为运营商为用户提供更高数据业务速率和容量的重要技术手段,但随着小基站部署密度的增大,会导致很多问题的出现,如频繁的切换失败,回程链路的非理想化等等。通过进一步研究小基站的增强技术,可以更好地改善这种多层混合组网的整体性能。为解决这些问题,文章针对不同场景进行了增益分析,并给出了潜在解决方案,最后通过分析对比,找到比较合适的小基站增强技术。

浅谈饰面砖装饰外墙外保温质量问题

直接粘贴在外墙面上的饰面砖使墙体承受两种外荷载:一是饰面砖及胶粘剂的自重,约合0.25kN/m2;二是风荷载(主要指负风压),在北京地区,离地20米高处最大负风压的计算值约2.1kN/m2,离地100米高处约3.6kN/m2(在沿海地区,此值可能达8-9kN/m2)。要靠胶粘剂与外墙面的粘结强度来承担。

Green synthesis of MIL⁃101/Au composite particles and their sensitivity to Raman detection of thiram

Metal⁃organic framework(MOF)MIL⁃101 and surface plasmon polariton(SPP)supported gold nanoparti⁃cles(Au NPs)hybrid systems were developed as a highly sensitive and reproducible surface⁃enhanced Raman scat⁃tering(SERS)detection platform,in which a green electrostatic self⁃assembly technology was adopted to construct the substrate.In an aqueous solution,the electronegativity of the particles can be used to prepare the composite sub⁃strate without any surface modifier.Due to the enrichment capacity of MIL⁃101 and the electromagnetic enhance⁃ment from Au NPs,the well⁃designed MIL⁃101/Au composites possessed ultrahigh sensitivity with the detection limit of Rhodamine 6G(R6G)as low as 10^(-10) mol·L^(-1).Meanwhile,the substrate exhibits high stability,excellent reproduc⁃ibility,and recyclability.Additionally,the novel substrate can be explored for direct capture,and sensitively detect pesticide residues such as thiram.

Surface Enhanced Raman Scattering on Self-assembled Nano Silver Film Prepared by Electrolysis Method

We demonstrate surface enhanced Raman scattering （SERS） detection of self-assembled nano silver film using a low-cost electrolysis strategy at a proper voltage and silver nitrate concentration in electrolyte. The concentration dependence of SERS from crystal violet （CV） molecules adsorbed to silver film was systematically studied. Importantly, the SERS surface enhancement factor of such nano silver film was 603, which was measured by a portable Raman spectrometer. The minimum concentration of detectable CV molecules can be as low as 10^-11 mol/L. The nano silver film prepared by this electrolysis method is an active, stable, cost-effective, and reusable SERS substrate.

Triangular Au-Ag framework nanostructures prepared by multi-stage replacement and their spectral properties

Triangular Au-Ag framework nanostructures （TFN） were synthesized via a multi-step galvanic replacement reaction （MGRR） of single-crystalline triangular silver nanoplates in a chlorauric acid （HAuCl4） solution at room temperature. The morphological, compositional, and crystal structural changes involved with reaction steps were analyzed by using transmission electron microscopy（TEM）, energy-dispersive X-ray spectrometry （EDX）, and X-ray diffraction. TEM combined with EDX and selected area electron diffraction confirmed the replacement of Ag with Au. The in-plane dipolar surface plasmon resonance （SPR） absorption band of the Ag nanoplates locating initially at around 700 nm gradually redshifted to 1 100 nm via a multi-stage replacement manner after 7 stages. The adding amount of HAuCl4 per stage influenced the average redshift value per stage, thus enabled a fine tuning of the in-plane dipolar band. A proposed formation mechanism of the original Ag nanoplates developing pores while growing Au nanoparticles covering this underlying structure at more reaction steps was confirmed by exploiting surface-enhanced Raman scattering （SERS）.

Synthesis of Cu2O/Ag Composite with Visible Light Photocatalytic Degradation Activity for in situ SERS Analysis

A multifunctional Cu2O/Ag micro-nanocomposite, which has the characteristics of high cat- alytic activities under the visible light and high surface-enhanced Raman scattering （SERS） activity, was fabricated via a facile method and employed for the in situ SERS monitoring of the photocatalytic degradation reaction of crystal violet. Through the variation of the AgNO3 concentration, Ag content on the Cu2O template can be controllably tuned, which has great influence on the SERS effect. The results indicate that Ag nanopartieles form on the Cu2O nanoframes to obtain the Cu2O/Ag nanoeomposite, which can act as an excellent bifunetional platform for in situ monitoring of photocatalytic degradation of organic pollutions by SERS.

Synthesis and optical properties research of gold nanoparticles with different morphologies

This paper presents an approach to synthesis of gold nanoparticles with different morphologies and investigation of the relationship between morphologies and their optical properties.Spherical gold nanoparticles with different sizes are synthesized via reduction method.Using seed-mediated solution growth method,gold nanoparticles with shuttle,star and stick shapes can be obtained.The sizes and morphologies of the gold nanoparticles are characterized by transmission electron microscopy （TEM）.The characterization results illustrate the growth process of the gold nanoparticles with different morphologies.Absorption spectroscopy and Raman spectroscopy measurements are performed to demonstrate the relationship between the morphologies and optical properties.The results of Raman characterization show that the gold nanoparticles with different morphologies can be used to probe molecules with different concentrations.

Adsorption Behaviors of 4-Mercaptobenzoic Acid on Silver and Gold Films

The adsorption behaviors of 4-mercaptobenzoic acid on silver and gold nanoparticles were studied by surface-enhanced Raman scattering （SERS） and density functional theory. The silver and gold films by electrodeposition have the same excellent characteristics as SERS- active substrates. At the same, the SERS spectra indicate that 4-mercaptobenzoic acid molecules are adsorbed on the surfaces of gold nanoparticles through the S atom, and that the carboxyl group is far away from surface of gold nanoparticles, and that there is a certain angle between the plane of benzene ring and gold film. However, 4-mercaptobenzoic acid molecules are adsorbed on the surfaces of silver nanoparticles through the carboxyl group, and the S atom is far away from surface of silver nanoparticles, and there is also a certain angle between the plane of benzene ring and the surface of silver nanoparticles. Here it is demonstrated the calculated Raman frequencies are in good agreement with experimental values, and the calculated Raman frequencies are also helpful to infer the adsorption behaviors of 4- mereaptobenzoic acid molecules.

Recent developments in visible-light photocatalytic degradation of antibiotics

With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such issues, various investigations on the removal of antibiotics have been undertaken. Photocatalysis has received tremendous attention owing to its great potential in removing antibiotics from aqueous solutions via a green, economic, and effective process. However, such a technology employing traditional photocatalysts suffers from major drawbacks such as light absorption being restricted to the UV spectrum only and fast charge recombination. To overcome these issues, considerable effort has been directed towards the development of advanced visible light-driven photocatalysts. This mini review summarises recent research progress in the state-of-the-art design and fabrication of photocatalysts with visible-light response for photocatalytic degradation of antibiotic wastewater. Such design strategies involve the doping of metal and non-metal into ultraviolet light-driven photocatalysts, development of new semiconductor photocatalysts, construction of heterojunction photocatalysts, and fabrication of surface plasmon resonance-enhanced photocatalytic systems. Additionally, some perspectives on the challenges and future developments in the area of photocatalytic degradation of antibiotics are provided.

Surface-enhanced Raman Scattering of Aflatoxin B1 on Silver by DFT Method

The structure, electrostatic properties, and Raman spectra of aflatoxin B1 （AFB1） and AFB1-Ag complex are studied by density functional theory with B3LYP/6- 311G（d,p）/Lan12dz basis set. The results show that the surface-enhanced Raman scattering （SERS） and pre-resonance Raman spectra of AFB1-Ag complex strongly depend on the adsorption site and the excitation wavelength found to enhance 102-103 order compared to of the incident light. The SERS factors are normal Raman spectrum of AFB1 molecule due to the larger static polarizabilities of the AFB1-Ag complex, which directly results in the stronger chemical enhancement in SERS spectra. The pre-resonance Raman spectra of AFB1-Ag complex are explored at 266, 482, 785, and 1064 nm incident light wavelength, in which the enhancement factors are about 10^2-10^4, mainly caused by the charge-transfer excitation resonance. The vibrational modes are analyzed to explain the relationship between the vibrational direction and the enhanced Raman intensities.

Ultimate flexural strength of normal section of FRP-confined RC circular columns

Numerical analysis is carried out to study the sectional properties of the fiber-reinforced polymer（FRP）-confined reinforced concrete（RC）circular columns. The axial load ratio, the FRP confinement ratio and the longitudinal reinforcement characteristic value are the three main parameters that can influence the neutral axis depth when concrete compression strain reaches an ultimate value. The formula for computing the central angle θ, corresponding to the compression zone, is established according to the data regression of the numerical analysis results. The numerical analysis results demonstrate that the concrete stress enhancement from transverse confinement and strain hardening of the longitudinal reinforcement can cause a much greater flexural strength than that defined by the design code. Based on the analytical studies and the test results of 36 large scale columns, the formula to calculate the flexural strength when columns fail under seismic loading is proposed, and the calculated results agree well with the test results. Finally, parametric studies are conducted on a typical column with different axial load ratios, longitudinal reinforcement characteristic value and FRP confinement ratios. Analysis of the results shows that the calculated flexural strength can be increased by 50% compared to that of unconfined columns defined by the code.

Controllable Electrochemical Synthesis of Silver Dendritic Nanostructures and Their SERS Properties

Ag dendritic nanostructures were synthesized on fluorine-doped tin oxide covered glass sub- strates by the electrodeposition method. Results demonstrate that the size, diameter, crys- tallinity, and branch density of the Ag dendrites can be controlled by the applied potential, the surfactants and the concentration of AgNO3. Three kinds of typical silver dendrites were applied as substrates of the surface enhanced Raman scattering （SERS） and one of them was able to clearly detect rhodamine 6G concentrations up to 0.1 nmol/L. The differences of the SERS spectra at these Ag dendrites confirmed that the shapes and interparticle spacings have great effect on Raman enhancement, especially the interparticle spacings.

Nonlinear Stark effect observed for carbon monoxide chemisorbed on gold core/palladium shell nanoparticle film electrodes, using in situ surface-enhanced Raman spectroscopy

The potential （E）-dependent vibrational behavior of a saturated CO adlayer on Au-core Pd-shell nanoparticle film electrodes was investigated over a wide potential range, in acidic, neutral, and basic solutions, using in situ surface-enhanced Raman spectroscopy （SERS）. Over the whole of the examined potential region （-1.5 to 0.55 V vs. NHE）, the peak frequencies of both the C-OM and the Pd-COM band （here, M denotes the multiply-bonded configuration） displayed three distinct linear regions： dvc oM/dE decreased from -185-207 （from -1.5 to -1.2 V） to -83-84 cm-1/V （-1.2 to -0.15 V）, and then to 43 cm-1/V （-0.2 to 0.55 V）; on the other hand, dvpd coM/dE changed from -10 to -8 cm I/V （from -1.5 to -1.2 V） to ^-31 to -30 cm-1/V （-1.2 to -0.15 V）, and then to -15 cm-1/V （-0.2 to 0.55 V）. The simultaneously recorded cyclic voltammograms revealed that at E 〈 -1.2 V, a hydro- gen evolution reaction （HER） occurred. With the help of periodic density functional theory calcula- tions using two different （2 × 2）-3CO slab models with Pd（111）, the unusually high dvc-oM/dE and the small dVPd-CoM/dE in the HER region were explained as being due to the conversion of COad from bridge to hollow sites, which was induced by the co-adsorbed hydrogen atoms formed from dissociated water at negative potentials.

Recent progress in Mg-Li matrix composites

Mg-Li matrix composites are one of the ideal structural materials in the fields of aerospace and military due to their high specific strength and stiffness, good damping and wear resistance, and small thermal expansion coefficient. The preparation technologies of Mg-Li matrix composites including powder metallurgy, pressure infiltration, stir-casting, foil metallurgy, and in-situ synthesis were introduced, and their advantages and disadvantages were compared. The common matrix alloys and reinforcements for Mg-Li matrix composites as well as the structure and performance of typical composites were mainly summarized. Then the interface chemistry between matrix and reinforcement was briefly reviewed. Finally, some problems existing at present and the possible solutions were discussed.