Local Surface Morphology Research Articles

Hybrid-feature based spherical quasi-conformal registration for AD-induced hippocampal surface morphological changes

Background and objectiveEstablishing accurate one-to-one morphological correspondence between different hippocampal surfaces is a solid foundation for the analysis of AD-induced hippocampal morphological changes. However, owing to the large variations between hippocampal surfaces, exiting registration work either fails to obtain the accurate matching of local and overall morphological features or does not preserve the bijectivity during parametric mapping. For this reason, this study proposes a hybrid-feature based spherical quasi-conformal registration (HSQR) method that can effectively maintain the diffeomorphic property while meeting the hybrid-feature matching constraints in the spherical parameter domain. MethodsThe HSQR algorithm is primarily achieved through hippocampal surface hybrid feature extraction and spherical quasi-conformal registration. First, hybrid features for a comprehensive morphological description of the hippocampal surface were established, which included essential anatomical features (landmarks) and mean curvature (intensity) features to ensure the accuracy of surface morphology alignment. Second, spherical parameterization was applied to genus-0 closed surfaces, such as the hippocampus, which maximized the preservation of the original local surface morphology through area-preserving properties. Third, a novel spherical quasi-conformal registration algorithm that can handle large deformations is established. It transforms a 3D spherical parameter domain into a 2D plane parameter domain using iterative local stereo projection to improve the efficiency of the registration algorithm. Subsequently, by controlling the Beltramin coefficient, the hybrid morphological features could be aligned while ensuring bijection before and after registration. ResultsUsing a cohort including 161 patients with amyloid-β (Aβ) positive Alzheimer disease (AD), 234 Aβ positive mild cognitive impairment (MCI) and 266 Aβ negative cognitively unimpaired (CU) individuals from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we set up the experiment which indicated that the HSQR-based whole bilateral hippocampal atrophy features demonstrated the stronger statistical power for group morphological differences of CU vs. MCI with q-value: 0.0453 for left hippocampus and 0.0401 for right hippocampus and group morphological differences of AD vs. MCI with q-value: 0.0282 for left hippocampus and 0.0421 for right hippocampus. ConclusionsOur registration algorithm may provide a solid foundation for the accurate quantification of hippocampal surface morphological changes for the differential diagnosis and tracking of AD.

Development of new lead free ceramic substrate for rectangular patch antenna application in X-band communication

This work introduces the use of Bi0.5Na0.5TiO3 (BNT) ceramic material as substrates for microstrip patch antennas operating within the frequency range of 8-12 GHz. The simulated antenna was constructed using a substrate composed of a synthesized ferroelectric perovskite-based material with a thickness of t=1.02 mm. This study investigated the intricate electromagnetic properties including permittivity, permeability, dielectric loss, magnetic loss, and miniaturization factor. Characterization techniques are used to investigate the crystal structure, local vibrational properties, surface morphology, and elemental composition of the synthesized sample. The reflection loss, return loss, and radiation pattern of the split ring microstrip patch antenna with a rectangular base were calculated using CST Microwave Studio version 2019. The parametric adjustment of the synthesized sample's uniqueness was achieved by modifying its thickness for t=0.7 mm, t=0.9 mm, t=1 mm, t=1.02 mm, and t=1.04 mm.

Comparative study of bubble forming sites at the laser-induced microstructure on a Ni electrode during hydrogen and oxygen evolution reactions

We study the formation of hydrogen and oxygen bubbles on the identical Ni electrode with a single laser-induced microstructure to understand the role of local surface morphology on bubble formation. All the forming sites of hydrogen bubbles are found at the microstructure, while those of oxygen bubbles are found not only at the microstructure but also on the flat area. Interestingly, not all but only a few of the sites at the microstructure produce both hydrogen and oxygen bubbles, and we find that these sites have partially confined structures. In contrast, the presence of oxygen bubble forming sites on the flat area implies that the local surface morphology is not the only decisive factor to be a bubble forming site. Through the elemental analysis of the electrode surface, we find the tendency that the sites with more nickel oxides show the less bubble forming activities.

Multiscale static and dynamic mechanical study of the Turritella terebra and Turritellinella tricarinata seashells.

Marine shells are designed by nature to ensure mechanical protection from predators and shelter for molluscs living inside them. A large amount of work has been done to study the multiscale mechanical properties of their complex microstructure and to draw inspiration for the design of impact-resistant biomimetic materials. Less is known regarding the dynamic behaviour related to their structure at multiple scales. Here, we present a combined experimental and numerical study of the shells of two different species of gastropod sea snail belonging to the Turritellidae family, featuring a peculiar helicoconic shape with hierarchical spiral elements. The proposed procedure involves the use of micro-computed tomography scans for the accurate determination of geometry, atomic force microscopy and nanoindentation to evaluate local mechanical properties, surface morphology and heterogeneity, as well as resonant ultrasound spectroscopy coupled with finite element analysis simulations to determine global modal behaviour. Results indicate that the specific features of the considered shells, in particular their helicoconic and hierarchical structure, can also be linked to their vibration attenuation behaviour. Moreover, the proposed investigation method can be extended to the study of other natural systems, to determine their structure-related dynamic properties, ultimately aiding the design of bioinspired metamaterials and of structures with advanced vibration control.

Noble-Metal Nanoparticle-Embedded Silicon Nanogratings via Single-Step Laser-Induced Periodic Surface Structuring.

Here, we show that direct femtosecond laser nanostructuring of monocrystalline Si wafers in aqueous solutions containing noble-metal precursors (such as palladium dichloride, potassium hexachloroplatinate, and silver nitrate) allows for the creation of nanogratings decorated with mono- (Pd, Pt, and Ag) and bimetallic (Pd-Pt) nanoparticles (NPs). Multi-pulse femtosecond-laser exposure was found to drive periodically modulated ablation of the Si surface, while simultaneous thermal-induced reduction of the metal-containing acids and salts causes local surface morphology decoration with functional noble metal NPs. The orientation of the formed Si nanogratings with their nano-trenches decorated with noble-metal NPs can be controlled by the polarization direction of the incident laser beam, which was justified, for both linearly polarized Gaussian and radially (azimuthally) polarized vector beams. The produced hybrid NP-decorated Si nanogratings with a radially varying nano-trench orientation demonstrated anisotropic antireflection performance, as well as photocatalytic activity, probed by SERS tracing of the paraaminothiophenol-to-dimercaptoazobenzene transformation. The developed single-step maskless procedure of liquid-phase Si surface nanostructuring that proceeds simultaneously with the localized reduction of noble-metal precursors allows for the formation of hybrid Si nanogratings with controllable amounts of mono- and bimetallic NPs, paving the way toward applications in heterogeneous catalysis, optical detection, light harvesting, and sensing.

Atomic simulation of surface damage of fused silica under laser irradiation

Fused silica optical element is the core component of the inertial confinement nuclear fusion ignition device. Due to the requirement of ignition conditions of the device for high power laser, the damage to fused silica optical element under strong laser is the key to restricting the operation of the ignition device. Therefore, the study of the surface damage of fused silica irradiated by laser is crucial to the development of the ignition device for inertial confinement nuclear fusion. In this paper, large-scale non-equilibrium molecular dynamics simulation method and micro-structure analysis technology suitable for dynamic process are proposed to study the damage process of fused silica surface under laser loading. Based on the theoretical study of high-temperature plasma fireball model, the damage of high-temperature fused silica plasma ball to surface is simulated. By tracking the local structure, temperature distribution and surface morphology, the factors affecting the surface damage of fused silica are analyzed. Our research results show that the size, distance from the surface, and temperature of high-temperature fused silica balls have important effects on the surface damage. We find that there are two different damage modes under the combined effect of the above factors. One is related to a rapid damage process, generating U-shaped voids and no further obvious damages after the surface spraying, and the other is dependent of a slow damage process: continuously expanding and resulting in a larger damage area. The surface morphologies formed by these two damage modes are consistent with the two typical damage morphologies observed in the experiments. This research can provide a guidance for understanding the complex damage process in fused silica under laser irradiation.

Flower-like ZnO Nanostructures Local Surface Morphology and Chemistry

This work presents the results of comparative studies using complementary methods, such as scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and thermal desorption spectroscopy (TDS) to investigate the local surface morphology and chemistry of flower-like ZnO nanostructures synthesized by the thermal oxidation technique on native Si/SiO2 substrates. SEM studies showed that our flower-like ZnO nanostructures contained mostly isolated and irregular morphological low-dimensional forms, seen as rolled-up floss flowers, together with local, elongated, complex stalks similar to Liatris flowers, which contained joined short flosses in the form of nanodendrites. Beyond this, XPS studies showed that these nanostructures exhibited a slight surface nonstoichiometry, mostly related to the existence of oxygen-deficient regions, combined with strong undesired C surface contamination. In addition, the TDS studies showed that these undesired surface contaminations (including mainly C species and hydroxyl groups) are only slightly removed from the surface of our flower-like ZnO nanostructures, causing an expected modification of their nonstoichiometry. All of these effects are of great importance when using our flower-like ZnO nanostructures in gas sensor devices for detecting oxidizing gases because surface contamination leads to an undesired barrier for toxic gas adsorption, and it can additionally be responsible for the uncontrolled sensor aging effect.

Effect of growth temperature on nitrogen incorporation into GaAsN during liquid-phase epitaxy

We studied the growth temperature effect on nitrogen incorporation into GaAsN layers grown by liquid-phase epitaxy (LPE). The growth of dilute nitrides at nearly equilibrium conditions during LPE presents several major challenges: low solubility of nitrogen in Ga-melt, small incorporation efficiency in the solid and high volatility of nitrogen. GaAsN layers are grown from three different initial epitaxy temperatures: 580 °C, 680 °C and 780° C using GaN powder in the melt as a source of nitrogen. The N content in GaAsN is estimated from X-ray diffraction curves applying Vegard’s law. The local microstructure and surface morphology of the grown layers are studied by Fourier-transform infrared spectroscopy and atomic force microscopy measurements, respectively. The absorption edge and the composition dependence of the effective band gap are determined by employing optical transmission and surface photovoltage spectroscopies.

InSAR assets in ground movements survey on abandoned coalfields

Rising groundwater in abandoned mines may result in ground movements at the surface overlying underground works. Feedbacks on several abandoned coalfields show that ground uplift is generally observed, reaching in some cases several centimetres or more. Although such ground movements, slow and associated with slight slopes, are not expected to generate surface damages, the survey of potential ground movements on abandoned coalfield is necessary, especially to confirm the end of mininginduced subsidence. The most common used method for this mission is levelling. A retro-analysis of ground movements, based on Interferometric Synthetic Aperture Radar (InSAR) technique, covering more than 20 years after mine activity ceasing, has been realised on the French abandoned coalfield of Nord-Pas de Calais. This analysis aimed to extend ground movements detection capabilities in areas not covered by levelling as well as compare InSAR analysis to levelling data for evaluating the robustness of satellite-based displacement measurements. InSAR analysis was able to highlight ground movements of a few millimetres per year, with the same order of precision than classical levelling methods. The observed ground displacement patterns expand well beyond the coalfield, indicating the influence of non-mining-induced phenomena, such as local geology and surface morphology. Our findings underline the operational capability of space-borne InSAR for monitoring abandoned coalfields.

The growth of nitrosobenzene adlayers on an Au(111) surface: The effect of experimental parameters

Dimerization of nitrosobenzenes also occurs at metal-solution interface which enables the design of azodioxy self-assembled bilayers. Formation of self-assembled adlayers is a dynamic process, dependent on various parameters. To gain new insights into the key experimental parameters governing a complex process of on-surface self-assembly and dimerization of nitrosobenzenes, here we studied the growth of adlayers of nitrosobenzene derivatives containing thiocyanate headgroup for adsorption on an Au(111) as a function of solution concentration and adsorption time. Ellipsometry revealed an increase in film thicknesses with increasing solution concentration and adsorption times, suggesting formation of more ordered adlayers and a greater tendency towards bilayers. This was supported by AFM and STM microscopy which showed variations in local surface morphology of adlayers in dependence on experimental parameters. It was found that higher solution concentration and longer adsorption times lead to formation of more ordered separate domains which were attributed to monolayers and bilayers.

The analysis of structural magnetic resonance imaging manifestation of hippocampus based on voxel and spherical harmonic surface morphometry in mesial temporal lobe epilepsy

Objective: To compare the hippocampal volume and local surface morphology changes in patients with mesial temporal lobe (mTLE) using the voxel-based morphometry and spherical harmonic methods respectively. Methods: A total of 66 patients (31 males and 35 females, age range from 17 to 48 (28±8) years) with mTLE and 80 age-and gender-matched controls (38 males and 42 females, age range from 19 to 46 (27±7) years) were retrospectively collected from July 2009 to February 2019 at Jinling hospital.. High resolution structural MRI of the whole brain, three-dimensional T1-weighted data(3DT1) were acquired from each subject. The changes of hippocampal volume and surface morphology were evaluated between mTLE groups and controls for observing the hippocampal atrophy pattern by using voxel-based morphometry and spherical harmonic shape descriptions point distribution model respectively. Pearson correlation analysis was conducted for observing the relationship between the morphological changes of hippocampus and disease duration. Results: Compared with the controls, hippocampal volume on the affected side in patients with mTLE was significantly reduced (Z-score:-1.55±0.57 vs 0.38±0.58, P<0.001) and negatively correlated with disease duration (r=-0.297, P=0.016). Furthermore, surface morphology analysis subtly showed that the atrophy of the affected hippocampus in patients with mTLE mainly located in the head, mesial lateral part and posterior tail of the hippocampus. Their displacement values were negatively correlated with disease duration (r=-0.336, P=0.006) and positively associated with the hippocampal grey matter volume (r=0.336, P=0.006). Conclusions: Voxel-based morphometry analysis reveals a global reduction in hippocampal volume, while the morphological measurement method based on surface shape can describe the local morphological changes of hippocampal atrophy.

Tailoring optical properties of surfaces in wide spectral ranges by multi-scale femtosecond-laser texturing: A case-study for TaB2 ceramics

The use of high power pulsed lasers is an effective tool for microstructuring material surfaces. It appears particularly useful when the material has some characteristics making difficult using other procedures (e.g. a high hardness). The present work reports on the femtosecond-laser treatment on tantalum diboride ultra-high temperature ceramics with different starting porosity fractions. The interaction with the laser beam creates a pattern with a complex multi-scale structure on the ceramic surface, whose characteristics depend on accumulated laser fluence and pristine porosity. Optical properties are significantly changed, allowing to separately optimize the interaction of the material with electromagnetic radiation spectrally located in different regions. As a case study, we apply the proposed strategy considering high-temperature solar thermal absorber applications, where the independent management of UV–Visible-Near IR radiation (sunlight) and Mid-IR (thermal radiation at the operating temperatures) are required. The correlation between the typical sizes of the realized multi-scale structures and the optical parameters (solar absorptance and thermal emittance in our example application) is discussed using an original predictive approach. The method here shown can be extended to every situation where materials are required to simultaneously interact with electromagnetic radiation in various spectral ranges. • Femtosecond laser-treatment creates a multi-scale surface pattern on ultra-hard TaB2 ceramics. • Local surface morphology and composition rely on accumulated laser fluence and pristine material porosity. • Optical properties are changed, with a remarkable increase of solar absorbance. • An original and simple method is described to correlate optical properties to the multi-scale surface characteristics. • The method is extremely useful to predictably optimize any surface interacting with light.

Surface Morphology Analysis of 1Cr11Ni2W2MoV Steel Subjected to Electrochemical Machining in NaNO3 Solution

Electrochemical machining (ECM) is a noncontacting method for machining complex contours that is independent of the hardness and strength of metals. Since the materials are removed in the form of ions via electrochemical dissolution, good surface integrity is a primary advantage of ECM. However, the selective dissolution of the metal phase and the differences in current density have significant effects on the local surface film composition and surface morphology of the machined sample. This paper focused on the morphology and the surface film composition of 1Cr11Ni2W2MoV heat-resistant steel after ECM processing. Herein, experiments were conducted with specialized fixtures. Moreover, the anodic polarization curve and current efficiency curve of 1Cr11Ni2W2MoV steel were obtained. The analysis of the experimental process and the examination of the specimens indicated that the material heterostructure and the current density seriously influenced the stability of the electrochemical dissolution process, and that carbide enrichment led to a poor-quality surface with a dense water ripple texture. Based on the experimental results, a three-layer metal dissolution model in NaNO3 solution was established. A machining current density of 30–40 A cm−2 for ECM of 1Cr11Ni2W2MoV steel was found to obtain good surface quality.

Comparison of corrosion resistance mechanism between ordinary Portland concrete and alkali-activated concrete subjected to biogenic sulfuric acid attack

The difference of corrosion resistance mechanism between alkali-activated concrete (AAC) and ordinary Portland cement concrete (OPC) under biogenic sulfuric acid corrosion was compared. By measuring the local surface morphology, mass loss, compressive strength and Ca2+ dissolution of OPC and AAC specimens, the corrosion resistance of these two kinds of concrete to biogenic sulfuric acid (BSA) was studied. The hydration products and corrosion products of OPC and AAC were studied with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and environmental scanning electron microscopy-energy dispersive spectroscopy (ESEM-EDS). The results show that under BSA corrosion, the thickness, roughness and porosity of the corrosion layer of OPC are obviously greater than those of AAC. The main corrosion products of OPC and AAC is gypsum. The amount of gypsum produced on the surface of OPC corrosion layer is larger than that of AAC. In addition, the bacterial effect on the surface of AAC corrosion layer is greater than that of OPC, which makes the corrosion path of BSA shorter than that of OPC. Therefore, the corrosion resistance of AAC to BSA is better than that of OPC.

Adhesion strength of titanium particles to alumina substrates: A combined cold spray and LIPIT study

The cold spray process and laser-induced projectile impact test (LIPIT) are used to deposit Ti powder particles on sintered polycrystalline Al2O3. Whereas LIPIT allows real-time observations of single particle impact and measurement of particle impact velocity, cold spray rapidly and simultaneously deposits particles with a wide range of deposition velocities and sizes. By use of these two techniques, the effect of particle velocity and substrate morphology on adhesion strength of single splats is investigated. The critical velocity for deposition is identified to be approximately 580 m/s for the Ti/Al2O3 system when using LIPIT and particles of 10 μm. Above the critical velocity, flattening ratio (FR) is also evaluated and observed to be linearly dependent on the particle impact velocity. Splat adhesion testing is performed on LIPIT-deposited as well as on cold spray-deposited powder particles to measure adhesion strength. This analysis shows that adhesion strength is highly affected by local substrate surface morphology, where particles bond more weakly to relatively smooth portions of the substrate. Therefore, mechanical bonding plays a significant role in adhesion. Also, adhesion strength decreases with an increase in FR and therefore velocity. This decrease can be associated with fracture of the ceramic substrate and rebound forces.

Initial Zinc Electrodeposition on Copper Studied By in-Situ AFM

Zinc deposition on copper surfaces is being studied before, mostly as a model system to understand film formation but more recently also in the context of catalysis or Zn batteries [1]. Electrochemical deposition of zinc on copper enables to obtain different ratios of Cu and Zn in the deposit alloy layers [2]. Zn electrodeposition on Cu surfaces can be monitored by in-situ Atomic Force Microscopy (AFM) and allows to follow the initial growth of Zn on different copper surfaces [3,4]. In this work, we pretreated different textured polycrystalline Cu surfaces by chemical etching and electropolishing to modify and improve the surface quality. Surfaces are then pre-characterized by AFM, Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD). The local surface morphology is changed after the different surface pretreatments. In-situ AFM measurements of Zn electrodeposition were performed on as-received as well as pretreated Cu surfaces and monitored the initiation of Zn deposition in real time (Figure 1). Deposition of Zn on Cu surfaces critically depends on the Cu surface morphology and specific surface orientations. For applications, the surface morphology of the Zn deposition may play a critical role in controlling the performance of the films.

Investigation of Al2O3 Wet-Chemical Coatings on Cathode Materials of Lithium-Ion Batteries

Coating targeted particles using a wet-chemical method is a simple, effective, and easy-to-scale-up method to coat protective oxide layers. Previous studies have shown that wet coating Al2O3 on the surface of Li-ion battery cathode materials can effectively prevent their chemical and structural degradation during charging-discharging processes, and improve the lifetime of batteries. However, there are still a limited number of systematic investigations of the wet coating process for Al2O3 coatings on cathode materials. The selection of precursors, solvents, coating loadings, annealing conditions, and even the compatibility between the Al2O3 coating and the underlying cathode material, are synthetic variables that can change the interfacial structure and electrochemical performance of the coated cathode. In this work, we used the wet-chemical method to synthesize a series of Al2O3-coated LiNixMnyCo1-x-yO2 (NMC) particles, with various precursor-solvent combinations, Al2O3 loadings, annealing conditions, and cathode compositions. Using nuclear magnetic resonance, electron microscopy and high-resolution X-ray diffraction techniques, we have shown that the structural and chemical evolutions of the surface coatings are highly dependent on annealing temperatures, cathode compositions and precursor-solvent combinations. Higher annealing temperature lead to a more homogeneous, smoother, and conformal coating on cathode materials with the formation of LiAlO2 phase. Organic solvents in place of water also lead to a more evenly and strongly bonded coatings, particularly under low-temperature treatment. We have also found that the crystallization temperature of the coating layers is precursor dependent. In addition, we have discovered that decreasing Mn content facilitates the diffusion of surface aluminum into the bulk in samples that have undergone high-temperature annealing. This facilitates a transfer of aluminum cations from the surface coating to become a bulk dopant. This is confirmed by local Al chemical environment evolution, local lattice distortion and surface morphology changes. Density functional theory calculations indicate that the incompatibility between Mn and Al could be the reason of the composition dependence of surface Al insertion. Finally, we demonstrate that the diffusion of Al into the bulk, the low temperature treatment, and the aqueous coating process lead to poor cyclability and low capacity in charging-discharging process, indicating the importance of the optimized wet coating protocols and coating-cathode compatibility to the electrochemical performance of coated cathodes. This work is important to the development of better coating methods for the next generation cathode materials in Li-ion batteries.

Surface Properties of Nanostructured, Porous ZnO Thin Films Prepared by Direct Current Reactive Magnetron Sputtering.

In this paper, the results of detailed X-ray photoelectron spectroscopy (XPS) studies combined with atomic force microscopy (AFM) investigation concerning the local surface chemistry and morphology of nanostructured ZnO thin films are presented. They have been deposited by direct current (DC) reactive magnetron sputtering under variable absolute Ar/O2 flows (in sccm): 3:0.3; 8:0.8; 10:1; 15:1.5; 20:2, and 30:3, respectively. The XPS studies allowed us to obtain the information on: (1) the relative concentrations of main elements related to their surface nonstoichiometry; (2) the existence of undesired C surface contaminations; and (3) the various forms of surface bondings. It was found that only for the nanostructured ZnO thin films, deposited under extremely different conditions, i.e., for Ar/O2 flow ratio equal to 3:0.3 and 30:3 (in sccm), respectively, an evident and the most pronounced difference had been observed. The same was for the case of AFM experiments. What is crucial, our experiments allowed us to find the correlation mainly between the lowest level of C contaminations and the local surface morphology of nanostructured ZnO thin films obtained at the highest Ar/O2 ratio (30:3), for which the densely packaged (agglomerated) nanograins were observed, yielding a smaller surface area for undesired C adsorption. The obtained information can help in understanding the reason of still rather poor gas sensor characteristics of ZnO based nanostructures including the undesired ageing effect, being of a serious barrier for their potential application in the development of novel gas sensor devices.

A dynamic monitoring approach for the surface morphology evolution measurement of plasma facing components by means of speckle interferometry.

Plasma Facing Components (PFCs) in a magnetically confined fusion plasma device will be exposed to high heat load and particle fluxes, and it would cause PFCs' surface morphology to change due to material erosion and redeposition from plasma wall interactions. The state of PFCs' surface condition will seriously affect the performance of long-pulse or steady state plasma discharge in a tokamak; it will even constitute an enormous threat to the operation and the safety of fusion plasma devices. The PFCs' surface morphology evolution measurement could provide important information about PFCs' real-time status or damage situation and it would help to a better understanding of the plasma wall interaction process and mechanism. Meanwhile through monitoring the distribution of dust deposition in a tokamak and providing an upper limit on the amount of loose dust, the PFCs' surface morphology measurement could indirectly contribute to keep fusion operational limits and fusion device safety. Aiming at in situ dynamic monitoring PFCs' surface morphology evolution, a laboratory experimental platform DUT-SIEP (Dalian University of Technology-speckle interferometry experimental platform) based on the speckle interferometry technique has been constructed at Dalian University of Technology (DUT) in China. With directional specific designing and focusing on the real detection condition of EAST (Experimental Advanced Superconducting Tokamak), the DUT-SIEP could realize a variable measurement range, widely increased from 0.1 μm to 300 μm, with high spatial resolution (<1 mm) and ultra-high time resolution (<2 s for EAST measuring conditions). Three main components of the DUT-SIEP are all integrated and synchronized by a time schedule control and data acquisition terminal and coupled with a three-dimensional phase unwrapping algorithm, the surface morphology information of target samples can be obtained and reconstructed in real-time. A local surface morphology of the real divertor tiles adopted from EAST has been measured, and the feasibility and reliability of this new experimental platform have been demonstrated.

Preliminary study of the flooding characteristics on proluvial fan under different peak discharges

The changes of flooding area and surface morphology on a proluvial fan from typical middle-small scale gully in Southwest China were studied under different peak discharges based on large scale of field solid model experiments. The results showed that: in the model fan, 1) the changes of flooding area and surface morphology before and after floods increased with the increases of peak discharges. Most flooding occurred on the concave bank around top rush point, which also made the local surface morphology changed dramatically, i.e. the increases of width-depth ratio of river channel. 2) Buildings on the upper fan less than 20m away from the river bank could be affected seriously by the extreme floods, while the distance on the lower fan was 40m. On the middle part of model fan, buildings less than 10m away from the river bank would suffer disasters under small floods, and the distances were 30m and 80m under middle and extreme floods, respectively.