Strawberry Maturity Recognition Algorithm Combining Dark Channel Enhancement and YOLOv5

Aiming at the problems of low accuracy of strawberry fruit picking and large rate of mispicking or missed picking, YOLOv5 combined with dark channel enhancement is proposed. In “Fengxiang” strawberry, the criterion of “bad fruit” is added to the conventional three criteria of ripeness, near-ripeness, and immaturity, because some of the bad fruits are close to the color of ripe fruits, but the fruits are small and dry. The training accuracy of the four kinds of strawberries with different ripeness is above 85%, and the testing accuracy is above 90%. Then, to meet the demand of all-day picking and address the problem of low illumination of images collected at night, an enhancement algorithm is proposed to enhance the images, which are recognized. We compare the actual detection results of the five enhancement algorithms, i.e., histogram equalization, Laplace transform, gamma transform, logarithmic variation, and dark channel enhancement processing under the different numbers of fruits, periods, and video tests. The results show that combined with dark channel enhancement, YOLOv5 has the highest recognition rate. Finally, the experimental results demonstrate that YOLOv5 is better than SSD, DSSD, and EfficientDet in terms of recognition accuracy, and the correct rate can reach more than 90%. Meanwhile, the method has good robustness in complex environments such as partial occlusion and multiple fruits.

Analytical fundamentals of migration in reflection seismics

We consider migration in reflection seismics from a completely analytical perspective. We review the basic geometrical ray-path approach to understanding the subject of migration, and discuss the limitations of this method. We stress the importance of the linear differential wave equation in migration. We also review briefly how a wavefield, travelling with a constant velocity, is extrapolated from the differential wave equation, with the aid of Fourier transforms. Then we present a non-numerical treatment by which we derive an asymptotic solution for both the amplitude and the phase of a planar subsurface wavefield that has a vertical velocity variation. This treatment entails the application of the Wentzel-Kramers-Brillouin approximation, whose self-consistency can be established due to a very slow logarithmic variation of the velocity in the vertical direction, a feature that holds more firmly at increasingly greater subsurface depths. For a planar subsurface wavefield, we also demonstrate an equivalence between two apparently different migration algorithms, namely, the constant-velocity Stolt Migration algorithm and the stationary-phase approximation method.

Analysis of a pilot valve and taper groove-based compound damping device

This paper describes the lumped mass parameter model of a pilot valve and taper rod-type compounded damping device used for high-speed and high-loading applications such as heavy artillery guns. The modelling of pilot valve and fluid interaction has been described by Euler equations and Laplace equations of potential flow in cylindrical polar coordinates for the axisymmetric situation. The viscosity effects in the model have been accounted through the inclusion of the damping term in the equation of motion of the pilot valve. The model presented has been experimentally validated using a test rig which is capable of simulating the firing impulse in the case of an artillery gun. The pilot valve results in a logarithmic variation in the orifice area of the damper leading to mechanical implementation of fault tolerance in the damper.

ON THE ORIGIN OF THE COSMIC MAGNETIC FIELD

It is shown how a cosmic magnetic field Bc can arise in the dimensionally reduced, heterotic superstring theory, via the logarithmic variation with temperature of the string gauge coupling parameter, assuming the ansatz where the asantaz ḡ≡0(α1α2α3)1/6, where the αi are the fine-structure constants of the electroweak and strong interactions. If [Formula: see text], where H0=100h km s −1 Mpc −1 is the Hubble parameter and s≫1 is a constant, then [Formula: see text]. Thus, for example, if s=3×103, then B c ≈3×10−6 G .

Effect of Polarization Rate in Potentiokinetic Anodic Polarization of iron in 1N H2SO4

Potentiokinetic data are reported for single crystal and polycrystalline specimens of high purity (56 ppm total impurities) and sulfurized (150 ppm sulfur) iron in 1N H2SO4. Eight polarization rates, ranging from 20 to 1100 mV/min, were investigated. The shape and position of potentiokinetic anodic polarization curves were found to vary appreciably and reproducibly with polarization rate. The observed logarithmic variation of three characteristic passive and transpassive current densities (ix) with polarization rate (η̇) can be expressed by a relation of the form where k and r are constants. The exponent r is given the name “polarization-rate-sensitivity.” At faster polarization rates, current densities tended to be higher and secondary passivity more pronounced. Secondary passivity merged with ordinary passivity at a material-dependent “critical” polarization rate, at which passive current densities were nearly independent of potential. Passive current densities increased with increasing potential at faster polarization rates, corresponding to Langmuir adsorption conditions, and decreased with increasing potential at slower polarization rates, corresponding to Temkin adsorption conditions. The presence and absence of sulfur and of grain boundaries had a negligible quantitative effect on the appearance of the potentiokinetic anodic polarization curve of iron in dilute sulfuric acid solution. However, a small effect of these chemical and physical variables could be expressed by different relations between currents and polarization rate.