This work investigates the influence of the direct laser texturing at high fluences (DLT-HF) on surface morphology, chemistry, and wettability. We use a Nd:YAG laser (
λ
= 1064 nm) with pulse ...duration of 95 ns to process stainless steel surface. The surface morphology and chemistry after the texturing is examined by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD), while the surface wettability is evaluated by measuring the static contact angle. Immediately after the texturing, the surface is superhydrophilic in a saturated Wenzel regime. However, this state is not stable and the superhydrophilic-to-superhydrophobic transition happens if the sample is kept in atmospheric air for 30 days. After this period, the laser-textured stainless steel surface expresses lotus-leaf-like behavior. By using a high-speed camera at 10,000 fps, we measured that the water droplet completely rebound from this superhydrophobic surface after the contact time of 12 ms.
A study of velocity and pressure fluctuations in the tip clearance flow of an axial fan is presented in this paper. Two different rotor blade tip designs were investigated: the standard one with ...straight blade tips and the modified one with swept-back tip winglets. Comparison of integral sound parameters indicates a significant noise level reduction for the modified blade tip design. To study the underlying mechanisms of the energy conversion and noise generation, a novel experimental method based on simultaneous measurements of local flow velocity and pressure has also been developed and is presented here. The method is based on the phase space analysis by the use of attractors, which enable more accurate identification and determination of the local flow structures and turbulent flow properties. Specific gap flow energy derived from the pressure and velocity time series was introduced as an additional attractor parameter to assess the flow energy distribution and dissipation within the phase space, and thus determines characteristic sources of the fan acoustic emission. The attractors reveal a more efficient conversion of the pressure to kinetic flow energy in the case of the modified (tip winglet) fan blade design, and also a reduction in emitted noise levels. The findings of the attractor analysis are in a good agreement with integral fan characteristics (efficiency and noise level), while offering a much more accurate and detailed representation of gap flow phenomena.
A new method for estimating the number of apple fruits and measuring their diameter in the orchard was developed and tested. A thermal camera captured images of apple trees five times during the ...vegetation period June–September 2001. Each time 120 images of twenty apple trees were recorded late in the afternoon to achieve a temperature gradient between fruits and their background. Recorded images were processed using several image processing algorithms. Correlation coefficients
R
2 from 0.83 to 0.88 were established between the manually measured fruit number and the estimated number based on a fruit detection algorithm. According to fruit development and the established growing curve, the value of the correlation coefficient,
R
2, increased during the ripening period. For measuring the fruit's diameter values of
R
2 between 0.68 and 0.70 were established. These slightly increased according to the fruit's colour and size development during the ripening period.
We perform tunneling measurements on indium antimonide nanowire-superconductor hybrid devices fabricated for the studies of Majorana bound states. At finite magnetic field, resonances that strongly ...resemble Majorana bound states, including zero-bias pinning, become common to the point of ubiquity. Since Majorana bound states are predicted in only a limited parameter range in nanowire devices, we seek an alternative explanation for the observed zero-bias peaks. With the help of a self-consistent Poission-Schrödinger multiband model developed in parallel, we identify several families of trivial subgap states that overlap and interact, giving rise to a crowded spectrum near zero energy and zero-bias conductance peaks in experiments. These findings advance the search for Majorana bound states through improved understanding of broader phenomena found in superconductor-semiconductor systems.
•Sustainable application is a way to reduce harmful influence to the living environment.•The establishment to estimate the canopy leaf area in crop protection.•Sensing system for digital canopy ...characterization.
This paper compares LIDAR and manual measurements of leaf area in orchards. The LIDAR measurements were performed in real orchard conditions. LIDAR data were used to count the number of points and to measure the canopy volume of individual volume elements. Manual measurements included defoliation, counting and leaf area measurements. Both types of measurements were performed in 8 volume elements for 20 apple trees of three different ages and varieties (‘Golden delicious’, ‘Jonagold’ and ‘Gala’). Using regression analysis, we estimated the relation between number of points in the cloud, canopy volume (both LIDAR measurements) and the leaf area (manual measurement). The maximum value of the correlation coefficient was 0.87816, when established from the relation between the number of points in the cloud and the canopy leaf area. The maximum value of the correlation coefficient was 0.80167, when established between the volume of tree canopy volume element and the leaf area.
This paper presents the impact of guard grill on aerodynamic integral characteristic, the spectrum of sound pressure level and total sound power level at four characteristic operating points of axial ...fans with standard guard grill, with optimized guard grill and without guard grill. The study of guard grill’s impact was conducted with measurements at integral level and local outflow velocity field of the axial fan without guard grill. The measurement results of the local outflow velocity field of the axial fan without guard grill at optimal operating point were used to model the optimized guard grill contour. The guard grill of axial fan has a significant impact on aerodynamic integral characteristic at free flow and mostly used operating region. The influence of guard grill is also characteristically reflected in the spectrum of sound pressure level via vortex shedding frequency and consequently at total sound power level of compared axial fans.
The research aims to demonstrate the basic system elements of a prototype automated orchard sprayer, which can deliver pesticide spray selectively with respect to the characteristics of the targets. ...The shape of the apple tree canopy was detected by a machine vision system using an RGB camera and appropriate image analysis. Information captured by RGB camera and processed by specific software was fed in real-time to a spraying arm, with three individually controlled sections, which adapt the pesticide spray flow to the canopy shape. The system allows variation in the liquid flow rate and volume of chemicals by means of controlled electric valves, whereby the amount of spray depends on the shape of the tree crowns. The current project focuses on developing the critical elements for spraying an individual tree and evaluates them in independent field experiments with the use of water sensitive papers (WSP). The demonstrated concept of precise application of pesticide sprays supports decreasing of the amount of delivered spray, thereby reducing both costs and environmental pollution.
Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to ...form the basis of topological quantum computing. We grew semiconductor indium antimonide nanowires that were coated with shells of tin of uniform thickness. No interdiffusion was observed at the interface between Sn and InSb. Tunnel junctions were prepared by in situ shadowing. Despite the lack of lattice matching between Sn and InSb, a 15-nanometer-thick shell of tin was found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4 teslas. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.
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