- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Deciphering controls for debris-flow erosion derived from a LiDAR-recorded extreme event and a calibrated numerical model (Ro?bichelbach, Germany)
摘要： Debris flows are among the most destructive and hazardous mass movements on steep mountains. An understanding of debris-flow erosion, entrainment and resulting volumes is a key requirement for modelling debris-flow propagation and impact, as well as analysing the associated risks. As quantitative controls of erosion and entrainment are not well understood, total volume, runout and impact energies of debris flows are often significantly underestimated. Here, we present an analysis of geomorphic change induced by an erosive debris-flow event in the German Alps in June 2015. More than 50 terrestrial laser scans (TLS) of a 1.2 km long mountain torrent recorded geomorphic change in comparison to an airborne laser scan (ALS) performed in 2007. Errors were calculated using a spatial variable threshold based on the point density of ALS and TLS and the slope of the digital elevation models. Highest erosion rates approach 5.0 m3/m2 (mean 0.6 m3/m2). During the event 9,550 ± 1,550 m3 was eroded whereas only 650 ± 150 m3 was deposited in the channel. Velocity, flow pressure, momentum and shear stress were calculated using a carefully calibrated RAMMS Debris Flow model including material entrainment. Here we present a linear regression model relating debris-flow erosion rates to momentum and shear stress with an R2 up to 68 %. Channel transitions from bedrock to loose debris sections cause excessive erosion up to 1 m3/m2 due to previously unreleased random kinetic energy now available for erosion.
关键词： erosion,numerical modeling,debris flow,geomorphic change,RAMMS,LiDAR
更新于2025-09-23 15:22:29
-
Homogeneous Large-area Quasi-freestanding Monolayer and Bilayer Graphene on SiC
摘要： In this study, we first show that the argon flow during epitaxial graphene growth is an important parameter to control the quality of the buffer and the graphene layer. Atomic force microscopy (AFM) and low-energy electron diffraction (LEED) measurements reveal that the decomposition of the SiC substrate strongly depends on the Ar mass flow rate while pressure and temperature are kept constant. Our data are interpreted by a model based on the competition of the SiC decomposition rate, controlled by the Ar flow, with a uniform graphene buffer layer formation under the equilibrium process at the SiC surface. The proper choice of a set of growth parameters allows the growth of defect-free, ultra-smooth and coherent graphene-free buffer layer and bilayer-free monolayer graphene sheets which can be transformed into large-area high-quality quasi-freestanding monolayer and bilayer graphene by hydrogen intercalation. AFM, scanning tunneling microscopy, Raman spectroscopy and electronic transport measurements underline the excellent homogeneity of the resulting quasi-freestanding layers. Electronic transport measurements in four-point probe configuration reveal a homogeneous low resistance anisotropy on both μm- and mm scales.
关键词： SiC terrace steps,polymer assisted sublimation growth,Epitaxial graphene,freestanding bilayer graphene,argon gas flow,graphene buffer layer,monolayer graphene,resistance anisotropy,large-scale graphene growth,freestanding monolayer graphene
更新于2025-09-23 15:22:29
-
Study of NH3 flow duty-ratio in pulsed-flow epitaxial growth of non-polar a-plane Al0.34Ga0.66N films
摘要： The effects of the modulation in the NH3 flow duty-ratio in a three-way pulsed-flow epitaxial growth process on the structural and optical properties of non-polar a-plane Al0.34Ga0.66N epi-layers were studied intensively. It was revealed that the typical pyramidal defects originated from the anisotropy in growth rate could be evidently reduced with an optimized NH3 flow duty-ratio. In fact, the root-mean-square value determined with atomic force microscope was decreased from 12.8 to 3.1 nm when the NH3 flow duty-ratio was increased from 0 to 0.57. Moreover, the LO-phonon-assisted exciton emission observed in the photoluminescence (PL) spectrum was remarkably suppressed, and the linewidth of the near band edge PL emission peak was decreased by 47%, implying the significantly enhanced optical properties of the non-polar a-plane Al0.34Ga0.66N epi-layer.
关键词： Pulsed-flow epitaxial growth,NH3 flow duty-ratio,Non-polar a-plane AlGaN epi-layers
更新于2025-09-23 15:21:21
-
Flow cytometric analysis of Xenopus laevis and X. tropicalis blood cells using acridine orange
摘要： Automated blood cell counters can distinguish cells based on their size and the presence or absence of a nucleus. However, most vertebrates have nucleated blood cells that cannot be counted automatically. We established an alternative automatic method for counting peripheral blood cells by staining cells with the fluorescent dye acridine orange (AO) and analysing cell populations using flow cytometry (FCM). As promising new animal models, we chose Xenopus laevis and three inbred strains of X. tropicalis. We compared the haematological phenotypes, including blood cell types, cell sizes, cellular structure, and erythrocyte lifespans/turnover rate among X. laevis and the three inbred strains of X. tropicalis. Each cell type from X. laevis was sorted according to six parameters: forward- and side-scattered light emission, AO red and green fluorescence intensity, and cellular red and green fluorescence. Remarkably, the erythrocyte count was the highest in the Golden line, suggesting that genetic factors were associated with the blood cells. Furthermore, immature erythrocytes in anaemic X. laevis could be separated from normal blood cells based on red fluorescence intensity. These results show that FCM with AO staining allows for an accurate analysis of peripheral blood cells from various species.
关键词： X. tropicalis,flow cytometry,acridine orange,blood cells,Xenopus laevis
更新于2025-09-23 15:21:21
-
Speciation and Determination of Ionic and Trace-Level Colloidal Silver in Selected Personal Care Products by Thermal Lens Spectrometry
摘要： The collinear dual beam thermal lens spectrometric (TLS) detection in batch mode (BM), as well as combined with the flow injection analysis (FIA), was applied to determine the colloidal silver in personal care products available in the public pharmacies and declared by producers to contain nanosilver at the level of 5-30 μg ml-1. It was found, that the examined samples contain mainly ionic silver (99% or more), whereas the colloidal form of silver is at the level of less than 1 μg ml-1. The TLS methods were confirmed to be fast, precise, highly accurate and highly sensitive with limits of quantitation of 0.30 ng ml-1 and 1.50 ng ml-1 and relative standard deviations not higher than 1.2% and 6.0% for BM- and FIA-TLS configuration, respectively. The developed TLS methods have nearly 60 times lower LOQ values concerning the colloidal silver determination than the classical spectrophotometric method. To verify the obtained results of the real sample analysis the total amount of ionic silver was determined by the use of ICP-OES technique.
关键词： Thermal lens spectrometric determination,Personal care products,Flow injection analysis,Silver nanoparticles,Colloidal silver
更新于2025-09-23 15:21:21
-
Exploiting lateral current flow due to doped layers in semiconductor devices having crossbar electrodes
摘要： Organic electronic devices such as light-emitting diodes, solar cells or rectifying diodes normally have a sandwich layer architecture stacked between the electrodes in a crossbar layout. Often however, the side effects of operating the devices in such an arrangement are either ignored or give rise to misinterpretations regarding the device performance or layer quality. For the sake of simplicity, device currents are typically assumed to exclusively flow in the direction vertical to the substrate, even though the conductivity of doped organic layers is high and gives rise to significant lateral current flows. Here, we study the vertical and lateral charge up along the n-doped and the p-doped layers as well as the resulting capacitance increase of charging the intrinsic layer outside the active area. We observe that controlling such lateral charging by structuring the doped layers can reduce the leakage current dramatically. We employ impedance spectroscopy to investigate the lateral charging responsibility for the capacitance increase at low frequencies. Modeling of the devices by a distributed RC circuit model yields information about the thickness, the conductivity, and the corresponding activation energy of both, the n-doped and the p-doped layers, simultaneously. We demonstrate that the capacitive effects from lateral charging can easily be misinterpreted as trap states in capacitance frequency characteristics. However, correct analysis with the proposed model actually yields rich and detailed post-fabrication information which can be utilized in device failure and degradation tests. Moreover, our results will aid the design and characterization of new electronic devices where lateral charge flow is part of the device concept.
关键词： Parasitic current,Leakage current,Impedance spectroscopy,Crossbar electrodes,Lateral current flow,Organic light-emitting diode,Capacitance,Organic solar cell,Structuring
更新于2025-09-23 15:21:21
-
[ACM Press the 2018 2nd International Conference - Barcelona, Spain (2018.08.03-2018.08.05)] Proceedings of the 2018 2nd International Conference on Cloud and Big Data Computing - ICCBDC'18 - Optical Flow Based Pose Estimation
摘要： In this paper, we present a new variant of ICP (iterative closest point) algorithm based on optical flow for finding better 3D point correspondence and computing six-degrees of freedom (6-DOF) pose of the rigid objects. Our approach integrates optical flow algorithm to ICP method, and proposed method gets advantage of higher resolution of the RGB sensor and depth information of the depth sensor. Fusing color and depth sensors improves pose estimation results. We set ground truth with Vicon motion tracker system. And, our approach is tested on a rigid object and compared to ICP method. Results have shown that optical flow and ICP method computes better rigid object pose estimation and lower error against ICP based pose estimation with only depth positions.
关键词： image projection,Iterative Closest Point (ICP),optical flow,Pose estimation
更新于2025-09-23 15:21:21
-
Selected properties of laser cladding coatings shaped using Flow drill technology
摘要： The paper presents the investigations of selected chemical and mechanical properties as well as macro- and microstructure of materials formed using thermal drilling process (Flow drill). The aim of this study was to determine the microstructure of the coatings produced using laser cladding with powder technology. The coatings were produced on the low-carbon steel using 1 kW disc laser. After modification of surface, the thermal drilling process was applied. To produce all coatings, the pure copper powder was used. In this study the laser power equal of 500, 700 and 900 W were used. The microstructure, chemical composition (EDS) and microhardness were investigation. It was found that the surface modification of low carbon steel and next conducted thermal drilling process caused change the surface properties on the hole flange. It was found that surface modification of steel using laser cladding with cooper powder and next Flow drill process contributes to the change in microhardness and chemical composition on hole flange.
关键词： microhardness,microstructure,laser cladding,chemical composition,Flow drill technology
更新于2025-09-23 15:21:21
-
Ultra-sensitive method based on time-resolved fluorescence immunoassay for detection of sulfamethazine in raw milk
摘要： A novel lateral flow assay (LFA) was developed by introducing Eu (III)-doped polystyrene nanoparticles (EuNPs) for rapid and ultra-sensitive detection of sulfamethazine (SM2) in raw milk. The limit of detection and linear range of the proposed method were 0.0045 and 0.05–10 ng/mL, respectively. The recovery of LFA for the detection of SM2 in raw milk was 96.1–108.2%. The proposed LFA provides a rapid and convenient strategy for fast and ultra-sensitive screening of SM2 in raw milk. EuNP-LFA may be a remarkable method for the detection of other targets at low concentrations to ensure food safety.
关键词： Lateral flow assay,sulfamethazine,raw milk,Eu (III)-doped polystyrene nanoparticle
更新于2025-09-23 15:21:21
-
Development of low vacuum laser welding technique using an aerodynamic window; ??o????a?????????¨???????????§??°?￠?????????????????o???￥???è??é????o;
摘要： In order to realize deep laser welding, conceptual application of a supersonic jet as an aerodynamic window was investigated. Detailed characteristics of the supersonic jet as the aerodynamic window were studied experimentally. Flow field of the supersonic jet was examined based on the schlieren flow visualization technique. As compared to a free-vortex flow design applied to the aerodynamic window nozzle, in the case of supersonic jet, oblique shock waves were captured both at the nozzle exit edge and the shear layer on the aerodynamic window. The velocity field under the condition that the shock-expansion wave was formed in the aerodynamic window was measured by the PIV (Particle Image Velocimetry) system (Koncerto II, Seika Digital Image Corp.). Both the vorticity magnitude and angular momentum were analyzed. Level of the vorticity magnitude in the core region of the supersonic jet was smaller by one-order than that in the shear layer in the region corresponding to the passage of laser-light (θ = 30 to 40° and r = 23.8 to 27.1 mm). The radial and circumferential velocity product in this region was similar to that observed under the free-vortex condition. In addition to the measurement mentioned above, pressure behavior was investigated using a multi-pressure measuring system (Scanivalve Corp. ZOC33). When the reservoir pressure was set at 800 kPa and diffuser width as 30.0mm, cavity pressure was reduced to 10.0 kPa. Under this reduced pressure environment, penetration depth increased by 2.6 times compared to penetration depth under atmospheric pressure environment. The effectiveness of the supersonic free-vortex aerodynamic window system tested in the high power laser welding manufacturing has been proven by the present study.
关键词： PIV,Aerodynamic window,High power laser welding,Flow visualization,Supersonic flow,Schlieren
更新于2025-09-23 15:21:01