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Determination of hydrological roughness by means of close range remote sensing
摘要： The objective of the presented work was to develop a method to acquire Manning’s n by creating very high-resolution surface models with structure-from-motion methods. As hydraulic roughness is an essential parameter for physically based erosion models, a practical measuring technique is valuable during field work. Data acquisition took place during several field experiments in the Lainbach valley, southern Germany, and on agricultural sites in Saxony, eastern Germany, and in central Brazil. Rill and interrill conditions were simulated by flow experiments. In order to validate our findings stream velocity was measured with colour tracers. Grain sizes were derived by measuring distances from a best fit line to the reconstructed soil surface. Several diameters from D50 to D90 were tested with D90 showing best correlation between tracer experiments and photogrammetrically acquired data. Several roughness parameters were tested (standard deviation, random roughness, Garbrecht’s n and D90). Best agreement in between the grain size and the hydraulic roughness was achieved with a non-linear sigmoid function and D90 rather than with the Garbrecht equation or statistical parameters.
关键词： soil erosion models,hydrological roughness,close range remote sensing,Manning’s n,structure-from-motion
更新于2025-09-10 09:29:36
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Effect of stacking faults and surface roughness on the thermal conductivity of InAs nanowires
摘要： Low thermal conductivity and high power factor are desirable for thermoelectric materials. These properties can be achieved by patterning devices into nano-structures such as nanowires (NWs). The thermal conductivity can be further reduced by altering the NW geometry through the introduction of surface roughness (SR) or stacking faults (SFs). In this paper, relaxation times for scattering of phonons at SFs and SR are developed to accurately compute the impact of both effects on the thermal conductivity of InAs NWs with different diameters. It is found that similar reductions of the thermal conductivity can be obtained with SFs instead of SR. For the shortest possible distance between SFs along a NW, the room temperature thermal conductivity can be reduced to 25% compared to an ideal NW. For a NW with rough surface, a more than 80% decrease of the thermal conductivity is possible for specific roughness profiles. All available experimental data on the lattice thermal conductivity of InAs NWs confirm the theoretical models and simulation results.
关键词： surface roughness,thermal conductivity,phonon scattering,stacking faults,InAs nanowires
更新于2025-09-10 09:29:36
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COMPARISON OF OPTICAL METHODS FOR CHARACTERIZATION OF GLASS MOSAIC WEATHERING
摘要： The work presented in this paper is a part of research project supported by Ministry of Culture and devoted to conservation of precious mosaic of "Last Judgement" on St. Vitus Cathedral in Prague. The aim of the project is to enhance external protective polymeric coating on glass tesserae of mosaic and also to develop optical method for assessment of coating’s surface conditions. The paper concentrates on comparison of various methods for surface evaluation assesses their advantages and disadvantages and also discusses their suitability for long term monitoring of coating state, namely re?ectometry, scanning probe microscopy, nanoindentation, white-light interferometry, and scanning electron microscopy. It is found that white-light interferometry and re?ectometry methods are the most suitable ones for monitoring purposes.
关键词： re?ectance,glass mosaic,surface,photometry,roughness
更新于2025-09-10 09:29:36
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A Method for Estimating the Filling Rate of the Mold Cavity in Nanoimprint Lithography
摘要： When the dimensions of a microelectronic structure decrease, high manufacturing costs are inevitable. A low cost and high throughput manufacturing technique for nanostructures is desired. Nanoimprint lithography involves patterning the resist through physical deformation by using a mold at nanoscale and has the potential to meet these expectations. Therefore, nanoimprint lithography has been extensively studied in recent years. Many real time measurements have been proposed for enhancing the yield of nanoimprint lithography. Among these measurements, the application of surface plasmon resonance has the advantage of quick, highly accurate analysis. In surface plasmon resonance application, the mold contains a gold ?lm for exciting surface plasmon resonance and an adhesion layer is applied to both sides of the gold ?lm to increase the lifespan of the mold. However, the effect of the geometric characteristics of the adhesive layer on the surface plasmon resonance spectrum and the mechanical strength of the mold has not been extensively studied. To improve the detection accuracy and reliability of the measurement, this study investigated the aforementioned effect. Analytical and experimental investigations con?rmed that the shape of the spectrum is in?uenced by the surface roughness and thickness of the titanium adhesion layer. To maintain the sharpness of the resonance dip, we suggest reducing the thickness of the titanium adhesion layer to below 6 nm and maintaining the surface roughness below 3 nm. Moreover, the proposed mold structure conforms to these requirements and is applied to estimate the ?lling rate. The measurement results demonstrate that the surface plasmon resonance spectrum is clearly affected by the mold ?lling. Speci?cally, the change in the surface plasmon resonance spectrum curve and resonance angle can indicate the quality of the imprinted pattern. This study demonstrates the effectiveness and high sensitivity of the proposed technique for estimating the ?lling rate of the mold cavity in nanoimprint lithography.
关键词： Nanoimprint Lithography (NIL),Surface Roughness,Filling Rate,Surface Plasmon Resonance (SPR),Non-Destructive Measurement
更新于2025-09-10 09:29:36
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Cathode plasma electrolytic deposition of Al2O3 coatings doped with SiC particles
摘要： Semiconductor particles doped Al2O3 coatings were prepared by cathode plasma electrolytic deposition in Al(NO3)3 electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7 μm and 40 nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5 g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5 g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings.
关键词： Cathode plasma electrolytic deposition,Surface roughness,Al2O3 coatings,SiC particles
更新于2025-09-10 09:29:36
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SCATTERING AND TRANSMISSION OF WAVES IN MULTIPLE RANDOM ROUGH SURFACES: ENERGY CONSERVATION STUDIES WITH THE SECOND ORDER SMALL PERTURBATION METHOD
摘要： Energy conservation is an important consideration in wave scattering and transmission from random rough surfaces and is particularly important in passive microwave remote sensing. In this paper, we study energy conservation in scattering from layered random rough surfaces using the second order small perturbation method (SPM2). SPM2 includes both first order incoherent scattering and a second order correction to the coherent fields. They are combined to compute the total reflected and transmitted powers, as a sum of integrations over wavenumber kx, in which each integration includes the surface power spectra of a rough interface weighted by an emission kernel function (assuming the roughness of each interface is uncorrelated). We calculate the corresponding kernel functions which are the power spectral densities for one-dimensional (1D) surfaces in 2D scattering problems and examine numerical results for the cases of 2 rough interfaces and 51 rough interfaces. Because it is known that the SPM when evaluated to second order conserves energy, and it can be applied to second order for arbitrary surface power spectra, energy conservation can be shown to be satisfied for each value of kx in the kernel functions. The numerical examples show that energy conservation is obeyed for any dielectric contrast, any layer configuration and interface, and arbitrary roughness spectra. The values of reflected or transmitted powers predicted, however, are accurate only to second order in small surface roughness.
关键词： roughness spectra,wave scattering,random rough surfaces,SPM2,transmission,passive microwave remote sensing,layered random rough surfaces,small perturbation method,power spectral densities,Energy conservation,dielectric contrast
更新于2025-09-10 09:29:36
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The investigation of the diameter dimension effect on the Si nano-tube transistors
摘要： The vertical gate-all-around (V-GAA) Si nano-tube (NT) devices with different diameter dimensions are studied in this work with the promising device performance. The V-GAA structure makes the transistor easy to be scaled down continuously to meet the complementary metal-oxide-semiconductor (CMOS) scaling requirements of the 7/10 nm technology node and beyond. The Si NT device with the hollow structure is demonstrated to have the capability to “deplete” and “screen-out” the out-of gate control carriers in the center of the NT and further result in the better device short channel control. Based on the study in this work, the V-GAA Si NT device with the optimized diameter dimension (= 20 nm) can benefit the Ion-state current and reduce the Ioff-state stand-by power simultaneously, due to the less surface roughness scattering and the better short channel control characteristics. The proposed V-GAA Si NT device is regarded as one of the most promising candidates for the future application of the sub-7/10 nm logic era.
关键词： diameter dimension effect,Si nano-tube transistors,short channel control,surface roughness scattering,vertical gate-all-around
更新于2025-09-10 09:29:36
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Optical vortex phase determination for nanoscale imaging
摘要： In this research we develop a principle of optical vortex phase analysis and its application to surface imaging with high accuracy measurements in nanoscale range. Two-coordinate scanning of the sample allow to retrieve an information about shape and roughness for optically transparent and reflecting surfaces exceeding optical diffraction limit. The interference between singular beam and reference wave, in general, carrying optical vortex with single or doubled topological charge allow to extract the data about phase delay caused by surface features or refraction. This method is also applicable for non-destructive testing of biological structures and live cells in real-time regime. Automatic processing of vortex interferograms allow to achieve a vertical and longitudinal resolution down to 1,75 nm and 7 nm respectively for visible light sources.
关键词： biological structures,nanoscale imaging,surface roughness,non-destructive testing,optical vortex phase analysis
更新于2025-09-09 09:28:46
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On-machine texturing of PCD micro-tools for dry micro-slot grinding of BK7 glass
摘要： While using diamond micro-tools for micro-grinding, tool re-clamping errors and low chip removal space from machining zone are the primary factors which cause large vibrations, higher grinding forces and poor surface quality. On-machine tool preparation and tool texturing prior to micro-grinding can reduce tool re-clamping error. It can further help to reduce the tool-workpiece contact area along with enhanced chip removal from the machining zone speci?cally essential during dry micro-grinding as usage of the cutting ?uid should be minimized or completely avoided for environmental aspects. In this study, end faces of polycrystalline diamond (PCD) micro-tools have been on-machine textured using micro electro-discharge machining (micro-EDM) process. Four types of textured tools are envisaged viz. tool with one micro-cavity at the center of the end face (T2), one micro-groove along the end face diameter (T3), two intersecting micro-grooves at the end face (T4) and four intersecting micro-grooves at the end face (T5). A new term “contact area ratio” is de?ned to explain the texture dimension on the end face of the micro-grinding tools. Performances of di?erent micro-textured tools (T2, T3, T4 and T5) with respect to a normal commercial tool (T1) in terms of grinding force, surface roughness and micro-slot quality are investigated for micro-slot grinding of BK7 glass. It is observed that micro-textured micro-grinding tool e?ciently serves the purpose of provisional chip collection in passive grinding areas of the tool whereas chip adhesion or wear on the active grinding areas signi?cantly gets reduced as compared to un-textured tools. Maximum reductions in the x and y direction forces are observed with tool type T5 compared to all other tool types. Reduction in z direction force is comparable for both tool types T2 and T3. Average surface roughness decreased from tool type T1 to type T2, T3 and up to tool type T4 whereas it again increased for tool type T5. The current study shows that textured micro-grinding tools are capable of reducing high normal forces, surface roughness and material dragging which are major concerns during micro-grinding with ?at-end poly-crystalline diamond tools.
关键词： Polycrystalline diamond tool,Micro-texture,Micro-grinding,BK7 glass,Surface roughness,Grinding force,Micro-EDM
更新于2025-09-09 09:28:46
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Effects of inclination angle on surface roughness and corrosion properties of selective laser melted 316L stainless steel
摘要： Balling effect is an inevitable defect during Selective laser melting (SLM) process, and it deteriorates the mechanical and corrosion properties of the resulting parts. In this work, the SLM process is used with various inclination angles to fabricate samples. The deep relationship between the selective laser melting process and the corrosion properties of the as-SLM fabricated parts is established to understand the effect of the inclination angle on the surface roughness, microstructure evolution, and corrosion properties of 316L stainless steel components. Results show that the Ra value of fabricated parts increased with increasing inclination angles. Inclination angles play an important role in balling and defect formation. Fabricated parts exhibit a wide passive region in salty environments. The corrosion resistance of the SLM samples after polishing is decreased comparing to that of the unpolished which attribute to porosity and balling behavior. The typical corrosion characterization of polished surface is pitting and localized corrosion, and it mainly origin of pores and balling. Meanwhile, balling behavior accelerated corrosion rates of non-polished parts.
关键词： Selective laser melting,Inclination angles,Surface roughness,Corrosion resistant
更新于2025-09-09 09:28:46