EXPERIMENT AND PARAMETER OPTIMIZATION OF ROOT-CUTTING FOR TRIMMING POSTHARVEST CABBAGE

Trimming for postharvest cabbage is useful to increase its economic value added. For obtaining the optimal root-cutting parameters, a root-cutting test platform based on universal testing machine was designed. Then shear contrast test and orthogonal test were carried out respectively, and shear properties were explained according to root morphology obtained by scanning electron microscope (SEM). The results showed that the effect of sliding-cutting with single-edged cutter was the best. The optimal parameters of cutter thickness, shear position, shear speed and sliding-cutting angle were respectively 0.89 mm, 0.00 mm, 388.94 mm/min and 34.84°, and the shear stress was 28.02 kPa.

Parabolic Equation Modeling of Scholte Waves and Other Effects Along Sloping Fluid-Solid Interfaces

Several methods for handling sloping fluid–solid interfaces with the elastic parabolic equation are tested. A single-scattering approach that is modified for the fluid–solid case is accurate for some problems but breaks down when the contrast across the interface is sufficiently large and when there is a Scholte wave. An approximate condition for conserving energy breaks down when a Scholte wave propagates along a sloping interface but otherwise performs well for a large class of problems involving gradual slopes, a wide range of sediment parameters, and ice cover. An approach based on treating part of the fluid layer as a solid with low shear speed is developed and found to handle Scholte waves and a wide range of sediment parameters accurately, but this approach needs further development. The variable rotated parabolic equation is not effective for problems involving frequent or continuous changes in slope, but it provides a high level of accuracy for most of the test cases, which have regions of constant slope. Approaches based on a coordinate mapping and on using a film of solid material with low shear speed on the rises of the stair steps that approximate a sloping interface are also tested and found to produce accurate results for some cases.

Applicability of ARFI elastography in the evaluation of canine prostatic alterations detected by b-mode and Doppler Ultrasonography

ABSTRACT The aim of this study was to assess the applicability of ARFI elastography for the complementary diagnosis of canine prostatic alterations. Twenty-two healthy dogs and 45 with prostatic alterations were diagnosed by the association of general and specific physical exams. Complete blood count, B-mode and Doppler ultrasound were performed. For the elastography study, tissue homogeneity and deformity were verified using the elastogram, and the shear velocities of the left and right lobes of all prostates were obtained. The change in tissue homogeneity was observed in 62.2% of the animals, while the shear speed was significantly higher in dogs with prostatic alterations, with a cut-off point > 2.35m/s as an indication of change. All animals in both groups were non-deformable. It was concluded that ARFI elastography is capable of providing qualitative and quantitative results that assist in the diagnosis of canine prostatic alterations in a non-invasive way.

Rheological Characteristics of Castor oil used as Biodegradable Lubricant

In this article I have presented the rheological characteristics of castor oil used as a biodegradable lubricant. The rheograms of castor oil have quite different slopes. The highest slope is at shear speed 3.3s-1, and the smallest slope is at 120s-1. From the representation of the dependence of the dynamic viscosity on the correlation coefficients at all the temperatures at which the castor oil has been was studied, the correlation coefficients have values close to the one value. The correlation coefficients have values between 0.985-0.990.

Micro-level Clearance Punching on NGO Electrical Steel

Non-grain-oriented electrical steel lamination is a critical component for the magnetic core. Punching such steel sheet with a large shear region, a low burr and small rollover is required to ensure accuracy. Densely packed grain deformation and plastic strain near cut surface are generally accompanied which detrimentally influence magnetic properties. In this study, micro-clearance (CL: 1 and 5 µm) punching of electrical silicon steel was conducted to investigate the influences of punching speed, micro-clearance, and counterforce on dimensional accuracy and microstructural changes. Electron backscatter diffraction analysis was performed to investigate the microstructural characteristics and detailed texture of specimens produced by shear speeds of 100, 260, and 600 mm/s with and without applied counterforce. Rollover height was found to be significantly reduced at a shear speed of 260 mm/s with applied counterforce under 1 µm clearance punching. The applications of counterforce and higher speed both significantly increased grain deformation, although the dimensional accuracy was improved. Grain conditions and the quality of cut surface were compared for different punching conditions to advance the understanding on the correlations between dimensional accuracy, grain deformation, and plastic strain.

Rheological Behavior of Biodegradable Lubricants

Biodegradable lubricants are of particular interest from the point of view of environmental protection. Generally, base oils for biodegradable lubricants may be: polyglycols, synthetic ester oils and vegetable oils. The vegetable oils used in this study are: oil sunflower, soybean oil and coconut oil. The rheological study was based on graphical representation of shear velocity based on shear stress using experimental data. The rheological models found in the literature are: Bingham, Casson, Ostwald-de Waele and Herschel-Bulkley. The article proposes three other rheological models of shear speed dependence on shear speed.

Study on BEOL Failures in a Chip by Shear Tests of Copper Pillar Bumps

A chip with 40 nm technology node and beyond generally incorporates low-k/ultra-low-k (LK/ULK) dielectric materials and copper traces in the back end of line (BEOL) to improve its electrical performance. Owing to the fragile low-k/ultra-low-k materials, the BEOL becomes vulnerable to external loads. When a copper pillar bump (CPB) above the BEOL sustains a shear force due to thermal mismatch between the components, failures occur in the microstructures of BEOL, especially in low-k materials. We fabricated CPBs on the chips and investigated fractures in the BEOL by a shear test approach. The shear speed and shear height are varied to examine their effects. The tested samples were analyzed via focused ion beam (FIB) and scanning electron microscope (SEM) to reveal the microstructures degradation or breaks in the BEOL, and they are classified into three kinds of failure modes. Assisted by a finite element analysis (FEA), the failure mechanism was explained and associated with the failure modes. The studies showed that the shear speed has a little influence on the maximum shear stress, but the increase of shear height leads to more fractures in the low-k materials. It indicated that decreasing the height of CPBs is helpful for reducing destruction risk of the BEOL under the thermomechanical loads. Based on a parametric study for shearing test simulation of a single CPB, the modulus and thickness of polyimide (PI) were found a larger impact on the stresses in the low-k material layer, but the modulus of low-k materials has a smaller effect on the stress. Generally, the shear test of a CPB can help to evaluate the integrity of BEOL in a chip.

Abnormality of the longitudinal Pochhammer–Chree waves in the vicinity of C2 phase speed

The exact solutions of the linear Pochhammer–Chree equation for propagating harmonic waves in a cylindrical rod are analyzed. Spectral analysis of the matrix dispersion equation for longitudinal axially symmetric modes is performed and analytical expressions for displacement fields are obtained. The variation of wave polarization on the free surface due to the variation of Poisson’s ratio and circular frequency is analyzed. It is observed that at the phase speed coinciding with the bulk shear speed all the components of the displacement field vanish, meaning that no longitudinal axisymmetric Pochhammer–Chree waves can propagate at this phase speed.