Morphological variability of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) cones in the context of seed extraction

In the paper generating curves given by fourth-degree polynomials were used to model the shape of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) cones from the Polish Forest Districts of Kołaczyce (one batch) and Opole (two batches), and to calculate the surface area and volume of individual cones. However, it was not possible to construct generalized equations for the surface area and volume of Douglas fir cones due to the high variability of empirical coefficients. The surface area and volume of the cones were also calculated from their length and diameter based on formulas for a cylinder and a barrel corrected by constants k1 and k2. The mean surface area of closed Douglas fir cones determined for the first, second, and third batch using the generating function was 4,348.4 mm2, 3,857.0 mm2, and 2,844.7 mm2, and the volume was 27,212.4 mm3, 21,012.9 mm3, and 12,844.4 mm3, respectively. The corresponding values calculated from the geometric formulas for solids were 4,332.0 mm2, 3,838.0 mm2, and 2,862.9 mm2 for the surface area and 27,366.0 mm3, 20,648.9 mm3, and 13,375.3 mm3 for the volume. The evaporation area of open cones was found to be five times greater than that of closed cones, with the difference being statistically significant. The outer and inner surfaces of scales taken from the middle segment of Douglas fir cones were photographed using a Quanta 200 scanning microscope (FEIC). The characteristic elements of scale morphology were evaluated by means of MultiScan Base software package. The outer and inner surfaces of Douglas fir scales were found to differ in some important ways, similarly as it has been reported in the literature for the Scots pine, silver fir, European larch, and black alder. The outer surface of scales is formed by thick-walled cells with marked protrusions, while the inner surface reveals cells with thin, frayed walls in the region adjacent to the seeds and wings. Knowledge of the geometry of Douglas fir cones and the morphology of their scales may be helpful in optimizing seed extraction parameters for those cones. Key words: seed extraction, model, shape curve, surface area, volume, scanning electron microscope

Direct Sampling for Recovering Sound Soft Scatterers from Point Source Measurements

In this paper, we consider the inverse problem of recovering a sound soft scatterer from the measured scattered field. The scattered field is assumed to be induced by a point source on a curve/surface that is known. Here, we propose and analyze new direct sampling methods for this problem. The first method we consider uses a far-field transformation of the near-field data, which allows us to derive explicit bounds in the resolution analysis for the direct sampling method’s imaging functional. Two direct sampling methods are studied, using the far-field transformation. For these imaging functionals, we use the Funk–Hecke identities to study the resolution analysis. We also study a direct sampling method for the case of the given Cauchy data. Numerical examples are given to show the applicability of the new imaging functionals for recovering a sound soft scatterer with full and partial aperture data.

A Depth Map Generation Method for Path Planning of Mobile Robot

Recently, the unmanned mobile robots have received broad applications, such as industrial and security inspection, disinfection and epidemic prevention, warehousing logistics, agricultural picking, etc. In order to drive autonomously from departure to destination, an unmanned mobile robot mounts different sensors to collect information around it and further understand its surrounding environment based on the perceptions. Here we proposed a method to generate high-resolution depth map for given sparse LiDAR point cloud. Our method fits the point cloud into a 3D curve and projects LiDAR data onto the curve surface, and then we make appropriate interpolations of the curve and finally implement the Delaunay triangulation algorithm to all the data points on the 3D curve. The experimental results show that our approach can effectively improve the resolution of depth maps from sparse LiDAR measurements.

Effect of device structure on signal measurement of zinc oxide nanocolumn-based resonant cavity hydrophones

Hydrophones with three different resonant cavities (microscope slide, cavity with 9.8 mm diameter and 5.7 mm[Formula: see text] curve surface, and cavity with 14 mm diameter and 6.5 mm[Formula: see text] curve surface) and with two different electrode structures (interdigital electrode, without the interdigital electrode but with top–bottom structure) were designed and fabricated. Zinc oxide (ZnO) film was deposited on indium–tin oxide/glass as seed layer and ZnO nanocolumns were grown as the piezoelectric material. Grown ZnO nanocolumns were used in all samples as the sound receiver of all designed hydrophones to enhance the sensing effect and efficiency of fabricated hydrophones. The electrode mask was then adhered on the surfaces of ZnO nanocolumns to complete the electrodes of designed resonant cavity. While measuring the hydrophones without interdigitated electrode, the measurement probes were contacted directly on the substrate and on the top layer of the material. Finally, the resonant cavities in all designed hydrophones were encapsulated using epoxy resin to finish the package of the fabricated hydrophones, and then the sound receiving performance of the hydrophones was evaluated in the water and the results were well compared in this study.

Testing MOdified Gravity (MOG) theory and dark matter model in Milky Way using the local observables

ABSTRACT In this paper, we have investigated one of the alternative theories to dark matter named MOdified Gravity (MOG) by testing its ability to describe the local dynamics of the Milky Way (MW) in vertical and transverse directions with the baryonic matter. MOG is designed to interpret the dynamics of galaxies and cluster of galaxies without the need for dark matter. We use local observational data such as the vertical dispersion, rotation curve, surface density, and number density of stars in the Milky Way to obtain the parameters of MOG and the baryonic component of MW by implementing a Bayesian approach to the parameter estimation based on a Markov Chain Monte Carlo method. We compare our results with the dark matter model of MW. The two models of MOG and cold dark matter are able to describe equally well the rotation curve and the vertical dynamics of stars in the local MW. The best values for the free parameters of MOG in this analysis are obtained as α = 8.99 ± 0.02 and μ = 0.054 ± 0.005 kpc−1. Also, we obtain the parameters of the generalized gNFW model in the dark matter model. Our best value of bulge mass from MOG is $(1.06 \pm 0.26)\times 10^{10}\, \rm M_{\odot }$, which is consistent with the estimations form the microlensing observations.

Preparation of complex surface coatings based on electrospark computer integrated deposition system

Purpose Electrospark deposition (ESD) attracts special attention from scientists and engineers because of its unique advantages. However, the ESD process has been carried out by hand up to the present. This prevents ESD from preparing complex curve/surface coatings owing to manual operation characteristics. To meet the coating precise preparation requirements for a lot of parts with complex surface from various industrial fields, this paper aims to obtain a new automatic ESD equipment, process and preparation methodology for complex surface coatings. Design/methodology/approach By designing a special deposition holder and re-programming programmable machine controller, an ESD power supply and a computer numerical control milling machine are integrated to obtain an electrospark-computer integrated deposition system (ES-CIDS). Then, based on the ES-CIDS, a new ESD process, named electrospark-computer numerical control deposition (ES-CNCD) is developed. Furthermore, complex surface coatings are depicted using non-uniform rational B-spline mathematical model and modeled in a special software developed via MATLAB. Finally, deposition programs for a complex coating are generated using golden section interpolation method, and transferred to and executed by the ES-CIDS to accomplish the preparation of the complex surface coating. Findings This paper demonstrates that it is possible and feasible to prepare complex surface coatings via an automatic ESD process (namely, ES-CNCD) precisely. Research limitations/implications This paper can make automatic ESD process get more attention from scientific researchers and engineers, and promote the research of the ES-CNCD process/equipment. Practical implications The ES-CNCD process can be used in the manufacturing of complex surface coatings, and in the remanufacturing of complex shape parts. Social implications The ES-CIDS/ES-CNCD can promote the development of related equipment and technology, and bring opportunities and employment to ESD industry. Originality/value This work prepares complex surface coatings precisely for the first time using a new automatic ESD process (ES-CNCD), which has wide application prospects in various industries.

Slowness curve surface acoustic wave transducers for optimized acoustic streaming

Adjusting focused IDT curvature according to the substrate slowness curve permits better focusing for enhanced acoustofluidic microparticle capture.

EXPERIMENTAL STUDY ON STEADY DYNAMIC FRICTION OF MWCNTs MIXED LUBRICANTS

This paper investigates the steady sliding behavior of multiwalled carbon nanotubes (MWCNTs) mixed lubricants at the metal–metal interface in direct shear tests. Slide-free-slide (SFS) experiments were performed to understand dynamic frictional stress of the sliding surfaces above the critical velocity. The experimental observations show that the dynamic stress decreases with increase in sliding velocity, but the same increases with normal stress. Further, in the case of change in concentration of the MWCNTs in the lubricant, the dynamic stress increases initially and then decreases to a minimum value and then further increases with addition of more nanoparticles in the lubricant. Dynamic stress and corresponding critical velocity are found to be minimum about 1.6% (wt./vol.) of MWCNTs concentration. Magnitude of cohesion as well as the coefficient of friction were also determined experimentally with the Coulomb friction law. The friction results are discussed in terms of the scaling laws in three regimes, namely viscous, rolling and sliding. These laws are justified on the basis of the mixed lubrication regime of Stribeck curve. Surface morphology of the test specimens before and after the experiment was also examined using SEM and EDS tests. No evidence of surface damage owing to motion of the nanoparticles was observed.

Protein adlayer thickness on colloidal nanoparticle determined by Rayleigh-Gans-Debye approximation

ABSTRACTReference materials (RM)-assisted Rayleigh-Gans-Debye approximation (rm-RGDA) has been developed and used to in situ determine the size and thickness of the adlayer on the particles in solution. The particle size determined by rm-RGDA is quite close to that measured by electron microscopy but significantly smaller than that measured by DLS. The BSA adlayer absorbed on PS50, PS100 and SiO2 NPs is 3.3, 0.9 and 1.2 nm, respectively, and close to those observed by SEM, which is 4.6, 1.3 and 3.8 nm, respectively. The FTIR analysis results show that the BSA absorbed on larger particles or hydroxyl-abundant surface, e.g. PS100 and SiO2 NPs can lose its secondary structure, e.g. α-helix, to a great extent and that absorbed on a more curve surface, e.g. smaller PS50 particles can largely preserve its secondary structure as its free state. The measurement results show the curvature of the NPs is closely related to the structure change of the adsorbed protein. This method provide a facile and new approach to measure the size and its adlayer change of the hybrid and core-shell structured nanoparticles in a wide range of wavelength.SIGNIFICANCEQuantitative study on the adsorption of the protein on colloidal nanoparticles is an important approach to understand the biophysical effect, compared with other ex situ methods such as TEM and SEM, where the specimen are undergone pre-processing and no longer the original state in measurement. It is, therefore, a big challenge. In order to cope with this challenge, UV-vis based RGDA has been developed and applied to in situ measure the size of the dispersed colloidal nanoparticles and their protein adlayer thickness, where the protein adlayer thickness on the colloidal nanoparticles can be easily determined. We believe this method provide a facile and sensitive way to in situ measure the dimension change of hybrid colloidal nanoparticles.