Lamb wave signal selective enhancement by an improved design of meander-coil electromagnetic acoustic transducer

In this paper, we investigate a method of selectively enhancing the single mode signal of a Lamb wave by using a meander-coil electromagnetic acoustic transducer （EMAT） with a new magnetic configuration. We use the Lamb antisym- metric （A0） mode and symmetric （SO） mode as an example for analysis. The analytical expression of the magnitude of the spatial Fourier transform of the Lorentz force generated by different meander coils is used to determine the optimal driving frequency for single mode generation. The numerical calculation is used to characterize the new magnetic configuration and the conventional EMAT magnet. Experimental examinations of each meander coil in combination with the conventional and new magnetic configuration show that the Lamb wave signal can be selectively enhanced by choosing the appropriate driving frequency and coil parameters through using the improved meander-coil EMAT.

Silicon-Based Grid Structure Photodiode with Selective UV Enhancement

Aiming at boosting the low ultraviolet (UV)re-sponsivity induced by thenegative impact of the surface 'dead layer' in silicon-based conventional photodiode (CPD), Siphotodiodes with five different structures, including both the novel grid structurephotodiode(GSPD)and CPD, have been manufactured using thermal diffusion process and tested. The results show thatthe UV responsivity around 365 nm of GSPD could be as high as 6 times that of CPD, while the highvisible (VIS) responsivity is sharply suppressed by the employment of grid shaped junction (GSJ) inthe GSPD, which has realized the expectation of selective UV enhancement with prospect forapplication.

Selective image enhancement method for low energy target information area

A selective subband enhancement method based on biorthogonal wavelet base is proposed. This novel image enhancement method is just for those images in which the energy of target information area is relatively lower. It includes two parts: one is enhancing the low frequency subband by wavelet decomposition and the other is building a new criterion based on entropy window to image evaluation. Experimental results show that this new scheme may result in a perfect image processing.

Enhancement of Selectivity in Capillary Zone Electrophoresis by Adding Ethanolamines or Ethylamines in the Running Buffer

Mono-, di-, tri-ethanolamines and di-, tri-ethylamines were used to prepare phosphate buffer at pH 2.5 and shown to be capable of enhancing the separation selectivity of chiral drug pinacidil and melittin in bee venom in capillary zone electrophoresis. The reason is due to the reduction of the average apparent mobilities of the analytes.

Generation of the wavelength-tunable XUV pulse using the two-color and three-color infrared pulses

We present an efficient method to generate an ultrashort wavelength-tunable XUV pulse by using the harmonic selec- tive enhancement scheme. The results show that by properly controlling the delay times of a two-color field or a three-color field, selective enhancement of the harmonics with photon energies between 80 eV and 315 eV can be obtained. Fur- ther, a wavelength-tunable and bandwidth-controllable XUV radiation can be obtained by Fourier transformation of these enhanced harmonics.

森林优化特征选择算法的增强与扩展

特征选择作为一种重要的数据预处理方法,不但能解决维数灾难问题,还能提高算法的泛化能力.各种各样的方法已被应用于解决特征选择问题,其中,基于演化计算的特征选择算法近年来获得了更多的关注并取得了一些成功.近期研究结果表明,森林优化特征选择算法具有更好的分类性能及维度缩减能力.然而,初始化阶段的随机性、全局播种阶段的人为参数设定,影响了该算法的准确率和维度缩减能力;同时,算法本身存在着高维数据处理能力不足的本质缺陷.从信息增益率的角度给出了一种初始化策略,在全局播种阶段,借用模拟退火控温函数的思想自动生成参数,并结合维度缩减率给出了适应度函数;同时,针对形成的优质森林采取贪心算法,形成一种特征选择算法EFSFOA(enhanced feature selection using forest optimization algorithm).此外,在面对高维数据的处理时,采用集成特征选择的方案形成了一个适用于EFSFOA的集成特征选择框架,使其能够有效处理高维数据特征选择问题.通过设计对比实验,验证了EFSFOA与FSFOA相比在分类准确率和维度缩减率上均有明显的提高,高维数据处理能力更是提高到了100 000维.将EFSFOA与近年来提出的比较高效的基于演化计算的特征选择方法进行对比,EFSFOA仍具有很强的竞争力.

Adsorption behavior of carbon dioxide and methane in bituminous coal:A molecular simulation study

The adsorption behavior of CO_2, CH_4 and their mixtures in bituminous coal was investigated in this study. First, a bituminous coal model was built through molecular dynamic(MD) simulations, and it was confirmed to be reasonable by comparing the simulated results with the experimental data. Grand Canonical Monte Carlo(GCMC)simulations were then carried out to investigate the single and binary component adsorption of CO_2 and CH_4with the built bituminous coal model. For the single component adsorption, the isosteric heat of CO_2 adsorption is greater than that of CH_4 adsorption. CO_2 also exhibits stronger electrostatic interactions with the heteroatom groups in the bituminous coal model compared with CH_4, which can account for the larger adsorption capacity of CO_2 in the bituminous coal model. In the case of binary adsorption of CO_2 and CH_4mixtures, CO_2 exhibits the preferential adsorption compared with CH_4 under the studied conditions. The adsorption selectivity of CO_2 exhibited obvious change with increasing pressure. At lower pressure, the adsorption selectivity of CO_2 shows a rapid decrease with increasing the temperature, whereas it becomes insensitive to temperature at higher pressure. Additionally, the adsorption selectivity of CO_2 decreases gradually with the increase of the bulk CO_2 mole fraction and the depth of CO_2 injection site.

Polyethylene imine functionalized porous carbon framework for selective nitrogen dioxide sensing with smartphone communication

Highly selective and remotely communicable nitrogen dioxide(NO_(2))sensing may contribute to future Internet of Things in environmental monitoring.However,room-temperature NO_(2)sensing materials such as carbon materials is still less than satisfactory due to their insensitive interaction with target gas.Here,polyethylene imine functionalized three-dimensional(3D)carbon framework(PEI/C framework)has been developed for enhanced selective NO_(2)sensing,via combined template synthesis and subsequent doping.Typically,the 3D PEI/C framework is observed porous shape with irregular coating.Beneficially,the response of C framework to NO_(2)increases while those of interfering gases decrease after being functionalized with PEI.Remarkably,the sensor prototypes show a 100 ppb-concentration detection limit at room temperature.Theoretically,such excellent NO_(2)sensing is attributed to the large specific surface ratio of porous 3D PEI/C framework,in which PEI serves as an active layer for target NO_(2),while a passivated one for interfering gases.Practically,such PEI/C framework sensor prototype is simulated for NO_(2)sensing device and communicated with a smartphone,showing great potential in future intelligent environmental monitoring.

Enhanced flow injection analysis for measurements of S-nitrosothiols species in biological samples using highly selective amperometric nitric oxide sensor

A highly selective nitric oxide（NO） sensor is fabricated and applied to devise an enhanced flow injection analysis（FIA） system for S-nitrosothiols（RSNOs） measurement in biological samples.The NO sensor is prepared using a polytetrafluoroethylene（PTFE） gas-permeable membrane loaded with Teflon AF？ solution,a copolymer of tetrafluoroethylene and 2,2-bis（trifluoroethylene）-4,5-difluoro -l,3-dioxole,to improve selectivity.This method is much simpler and possesses good performance over a wide range of RSNOs concentrations.Standard deviation for three parallel measurements of blood plasma is 4.0%.The use of the gas sensing configuration as the detector enhances selectivity of the FIA measurement vs.using less selective electrochemical detectors that do not use PTFE/Teflon type outer membranes.

In-situ grown CuO_(x)nanowire forest on copper foam:A 3D hierarchical and freestanding electrocatalyst with enhanced carbonaceous product selectivity in CO_(2)reduction

Electrocatalytic carbon dioxide(CO_(2))reduction is considered as an economical and environmentally friendly approach to neutralizing and recycling greenhouse gas CO_(2).However,the design of preeminent and robust electrocatalysts for CO_(2)electroreduction is still challenging.Herein,we report the in-situ growth of dense CuO_(x)nanowire forest on 3D porous Cu foam(CuO_(x)-NWF@Cu-F),which can be directly applied as a freestanding and binder-free working electrode for highly effective electrocatalytic CO_(2)reduction.By adjusting the surface morphology and chemical composition of CuO_(x)nanowires via surface reconstruction,large electrochemically active surface area and abundant Cu(+1)sites were generated,leading to remarkable activity for CO_(2)electroreduction.The as-prepared hierarchical conductive electrode exhibited an enhanced Faradaic efficiency of 15.0%for ethanol formation(FE_(C_(2)H_(5)OH))and a total Faradaic efficiency of 69.4%for all carbonaceous compounds(FE_(C-total))at a mild applied potential of–0.45 V vs.RHE in 0.1 M KHCO_(3)electrolyte.It achieved a 4-fold increase in FE_(C-total)than that of Cu nanowire forest supported on 3D porous Cu foam(Cu-NWF@Cu-F)obtained by in-situ reduction of the CuO_(x)-NWF@Cu-F via annealing at H_(2)atmosphere,and thereby effectively suppressed the hydrogen evolution side-reaction.