1,690 research outputs found
The influence of bromine adsorption on copper electrodeposition on polycrystalline gold electrodes modified with self-assembled monolayers
No full textThe influence of bromine adsorption on copper electrodeposition on a polycrystalline gold electrode modified with self-assembled monolayers (SAMs) has been investigated by chronoamperometry and cyclic voltammetry. It was found that the deposition potential of copper was shifted negatively due to the SAMs. The hydrogen bond interaction between ?-carboxyl thiols decreased the defect density of the SAMs and significantly retarded the deposition of copper. The presence of bromide anions also shifted the potential more negatively through adsorption into the defects of SAMs
Template synthesis of well-aligned titanium dioxide nanotubes
No full textTiO2 nanotubes of the anatase form have been synthesized by sol-gel chemical method using anodic aluminum oxide (AAO) as a template. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction were used to investigate the structure and morphology of the TiO2 nanotubes. The results showed that TiO2 nanotubes obtained are highly ordered and uniform. The diameter and length of the obtained nanotubes were determined by the pore size and the thickness of AAO template. It was found that through control of immersion time of AAO membrane insol, both tubules and fibrils can be prepared
Electrochemical behavior of Au colloidal electrode through layer-by-layer self-assembly
No full textElectrodes formed by Au colloidal nanoparticles have been obtained by layer-by-layer self-assembly using 1,6-hexanedithiol as cross-linkers. Cyclic voltammograms show that the peak-to-peak separation decreases as the number of Au colloidal layers increases. After seven layers of Au colloidal particles have been deposited, the multilayer electrodes have the electrochemical properties of metallic Au and show ideal microelectrode behavior. An equivalent circuit for the electrochemical impedance spectroscopy was established to model the working electrode. It is evident that by increasing the layer number of Au colloidals, the interfacial electron transfer is promoted, implying the electron-transfer process changes from a kinetically limited process to a diffusionally limited process
Copolymerization of pyrrole and aniline nanofibrils and field emission property of the resulting copolymer
No full textFIGURE 6. Gastrochilus labrosus Q. Liu & X.H in New species and record of Gastrochilus (Orchidaceae, Aeridinae) from China and Laos
No full textFIGURE 6. Gastrochilus labrosus Q. Liu & X.H. Jin, sp nov. A. Habitat. B. Plant with flowers and fruits. C. Inflorescence. D & L. Abaxial and adaxial leaf. E. Flower. F. Sepals and petals. G & H. Front and lateral view of labellum. I. Back view of lip. J. Pollinarium. K. Anther cap.Published as part of Liu, Qiang, Wu, Xun-Feng, Zhou, Shi-Shun, Li, Jian-Wu & Jin, Xiao-Hua, 2023, New species and record of Gastrochilus (Orchidaceae, Aeridinae) from China and Laos, pp. 210-224 in Phytotaxa 585 (3) on page 218, DOI: 10.11646/phytotaxa.585.3.3, http://zenodo.org/record/769080
Mesozoic shoshonitic intrusives in the Yangchun Basin, western Guangdong, and their tectonic significance: II. Trace elements and Sr-Nd isotopes
No full textGenetic relationships among CIMMYT subtropical QPM and Chinese maize inbred lines based on SSRS
No full textSpace-varying FIR filter design for nonuniformly sampled seismic data
No full textSince the early days of exploration seismology seismic receiver field arrays have been employed for purposes such as suppressing high wavenumbers present in wavefield, reducing the volume of recorded data and improving its signal-to-noise ratio. These receiver field arrays rely on the receivers being placed on a predetermined geometric layout, a condition which is not always met in the field. Misplacing receivers can have a detrimental effect on the performance of the field array. Fortunately, advances in seismic acquisition now enable a) recording the output of individual receivers and b) knowing with high (but limited) accuracy the actual location of each receiver. It is possible then to form arrays digitally on a computer, a process known as group forming. Group forming can be viewed as a combination of filtering and resampling. We propose two algorithms that take advantage of the positional information available about the receivers and generate a linear space-varying (LSV) filter. The LSV filter is suitable for filtering the nonuniformly sampled data, generating the filtered output on the nominal grid. We examine the relation of our algorithms with other algorithms from the bibliography and investigate their performance on synthetic data.MSc. track TelecommunicationsElectrical EngineeringElectrical Engineering, Mathematics and Computer Scienc
Imaging and Suppressing Near-Receiver Scattered Seismic Waves
No full textCivil Engineering and Geoscience
Low-frequency SNR improvement of refracted waves by cascaded correlation and convolution
No full textSeismic interferometry is the process where new impulse responses, i.e. Green’s functions, are retrieved between two points by cross-correlation, convolution or deconvolution of wavefield responses. Seismic interferometry is also referred to as Green’s function retrieval. Newly retrieved Green’s function might contain spurious events that arise due to strict requirements for Green’s function representation for seismic interferometry that are not met in practice. Methods exist for the suppression of spurious events; however, it is shown in various studies that spurious events can be very useful. The virtual refraction is a well-known coherent spurious event that arises when refracted waves are correlated. This event can upon stacking be strongly enhanced with sources located post-critically in the stationary-phase region, which complies with typical 2D exploration source and receiver geometries. This event contains information of the velocity and depth of layers that cause waves to be guided along an interface (refraction). Source-receiver interferometry additionally to cross-correlation adds convolution to retrieve a Green’s function between a source and receiver, hereby turning a virtual refraction into a refraction with the same traveltime characteristics as the original refracted wave. This work explains how source-receiver interferometry can be applied to refracted waves. Synthetic seismic data and controlled-source field data shot in the desert in Oman are used to apply source-receiver refraction interferometry. Results show how signal-to-noise ratio for random noise as well as coherent noise refracted waves is improved in long-offset data.Applied Geophysics and PetrophysicsGeoscience & EngineeringCivil Engineering and Geoscience
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