Investigation on cutting mechanism in small diameter drilling for GFRP (thrust force and surface roughness at drilled hole wall)

This study describes the relation between the cutting force and the surface roughness of a drilled hole wall in small-diameter drilling of GFRP for a printed wiring board. In order to investigate the characteristics of small diameter drilling for GFRP, the surface of the drilled hole wall is observed by SEM, and the surface roughness along the feed direction is measured at various edge position angles of the drilled hole. The cutting force during drilling is measured. Moreover, the thrust force is devided into two components (the static component and the dynamic component). It is shown that the dynamic components are related with the surface roughness of the drilled hole wall. In conclusion, it is found that the major cutting edge of the drill is more influential in the quality of the drilled hole wall than the chisel edge of the drill in small diameter drilling of PWB.     

Hydrogen trapping in Ferrovac E-iron,mild steel and 4340 steel

Hydrogen diffusion rates through Ferrovac E-iron, mild steel and 4340 steel have been studied using an electrochemical permeation cell. Thermal-mechanical processing included cold rolling and annealing and, in case of 4340 steel, quench and tempering. Apparent diffusion coefficients were determined from the slope of plots of log [(P-P₀)√t] versus 1/t where P, P₀ and t are the permeation rate at time t, the initial permeation rate and the time, respectively. Apparent diffusion coefficients are dependent on processing. Cold rolling and quenching produce trap sites that are annihilated during annealing and tempering, respectively. These traps are associated with lattice imperfections. In addition, the steels have trap sites at the interface between different phases. Both types of traps behave reversibly.     

Mining of Moving Objects from Time-Series Images and its Application to Satellite Weather Imagery

The framework of mining of moving objects from image data sequence is presented. Scenes are first clustered and labeled by using two-stage SOM that is modified to recognize images including similar moving objects as the same cluster, and that well recognizes scenes including prominent objects. After extraction of images which include prominent objects based on clustering result, the position and the shape of objects are approximated by using mixture gaussian model via EM algorithm, providing the adequate or larger number of components. By adopting the average of the data points in the smaller blocks as the initial parameters, the solutions are stabilized and the identification of components among time-series images and the tracking of a specific object become easier.This framework is applied to a four-year (ranging from 1997 to 2000) dataset of cloud images taken by Japanese weather satellite GMS-5 to evaluate its performance. Modified SOM method well classifies scenes which include prominent moving object, and seasonal variation tendency is detected in the cluster ID sequence. The result of object detection via EM algorithm for summer-type images including clear cloud masses such as typhoons shows that this approach well approximate the adequate distribution of cloud masses in many cases. Objects in the very irregular shapes are also well represented as the mixtures of gaussians.The extracted object information, together with the scene clustering result, is expected to offer us a rich source for knowledge discovery of video datasets. This approach is one of the effective ways of mining video images whose characteristics are unknown in advance, and thus applicable to the various type of applications.     

Development of a three-dimensional magnetohydrodynamics code for electromagnetic pumps

Annular linear induction pumps (ALIPs) are one of the electromagnetic (EM) pumps, which drive liquid metal using EM force, for fast reactors and have been developed in many countries. An ALIP mainly consists of multiple coils, iron cores and an annular flow channel. We have calculated the developed pressure of ALIPs using a two-dimensional magnetohydrodynamics (MHD) code. There are some reports in which pressure drop and fluctuation were observed in EM pump operations near the top of the pressure and flow rate relation (P–Q) curve. For fear of this phenomenon, the EM pump design is sometimes too conservative. To simulate the pressure drop and fluctuation occurrence conditions, we have developed a new three-dimensional (3D) MHD code. Clarification of this condition and its phenomena in the sodium flow will enable design of a new structure or determination of operation conditions that preclude this pressure drop and fluctuation and, thereby, achieve high efficiency. In this paper, the model of our new 3D MHD code, the accuracy of the code, simulation results focusing on pressure drop and fluctuation by radial and circumferential vortices are reported.     

The Roles of the Ge‐Te Core Network and the Sb‐Te Pseudo Network During Rapid Nucleation‐Dominated Crystallization of Amorphous Ge2Sb2Te5

Ge₂Sb₂Te₅ (GST) has demonstrated its outstanding importance among rapid phase‐change (PC) materials, being applied for optical and electrical data storage for over three decades. The mechanism of nanosecond phase change in GST, which is vital for its application, has long been disputed: various, quite diverse scenarios have been proposed on the basis of various experimental and theoretical approaches. Nevertheless, one central question still remains unanswered: why is amorphous GST stable at room temperature for long time while it can rapidly transform to the crystalline phase at high temperature? Here it is revealed for the first time, by modelling the amorphous structure based on synchrotron radiation anomalous X‐ray scattering data, that germanium and tellurium atoms form a “core” Ge‐Te network with ring formation. It is also suggested that the Ge‐Te network can stabilize the amorphous phase at room temperature and can persist in the crystalline phase. On the other hand, antimony does not contribute to ring formation but constitutes a “pseudo” network with tellurium, in which the characteristic Sb–Te distance is somewhat longer than the covalent Sb–Te bond distance. This suggests that the Sb‐Te pseudo network may act as a precursor to forming critical nuclei during the crystallization process. The findings conclude that the Ge‐Te core network is responsible for the outstanding stability and rapid phase change of the amorphous phase while the Sb‐Te pseudo network is responsible for triggering critical nucleation.     

Comparison between Conventional and Improved Gas Engine-Driven VRF under Same Climate Conditions

This paper reports the on-site performance evaluation of conventional and improved gas engine-driven VRF （variable refrigerant flow） units and （abbreviated as GHP） units. The study aims to elucidate two actual GHP units by using the probe insertion method. There is a tendency to decrease energy efficiency compared to a high loading factor. GHP operation was almost all part load operation. This on-site evaluation indicates a clear difference between conventional and improved GHP.     

线损电价测算中线损率计算方法的探讨

阐述了统计线损率与电压累计线损率的概念及两者的差别,运用典型的电网图举例说明了各电压等级统计线损率和电压累计线损率的计算方法,介绍了通过各电压等级统计线损率及一些辅助参数计算电压累计线损率的方法,解决了线损电价测算中电压累计线损率的计算问题,并针对各电压等级不同的情况提出了修正建议;最后通过计算实例验证了这种方法的实用性.     

Surface crystallization and second-order optical non-linearity in Gd2O3–Bi2O3–B2O3 glasses

Some ternary Gd₂O₃–Bi₂O₃–B₂O₃ glasses are prepared, and crystallization behavior and second harmonic intensity are examined to develop new non-linear optical crystallized glasses. The glasses with Gd₂O₃ contents of 8–14 mol% have large densities of over 6 g/cm³ and large refractive indices of ～ 1.9. Transparent surface crystallized glasses consisting of two kinds of crystalline phases with different morphologies, i.e. plate shape and needle shape crystals, are fabricated by heat-treatment at temperatures between glass transition and crystallization temperatures. From second harmonic generation microscope observations, micro-Raman scattering spectra and XRD analyses, plate shape crystals are determined to be non-linear optical Gd_xBi_1KxBO₃ and needle shape crystals are Bi₃B₅O₁₂ having no second-order optical non-linearity. Since crystallized glasses consisting of Gd_xBi_1KxBO₃ crystals exhibit relatively strong SHGs, they have a high potential for application to light control devices.     

Electronic structure and surface morphology of [6,6]-phenyl-C71-butyric acid methyl ester films

We investigate the electronic structure of [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₀BM) films by ultraviolet photoelectron and inverse photoemission spectroscopy. We discuss the electronic structure of PC₇₀BM in comparison with C₇₀ and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₀BM). The molecular orbitals around the energy gap of PC₇₀BM are broadly distributed due to the low symmetry of the molecular structure. Consequently, the energy gap of PC₇₀BM is smaller than that of C₇₀ and PC₆₀BM. The film deposition method affects the polarization energy between the PC₇₀BM molecules, and thus affects the electronic structure of the films.     

Effects of SCF content,injection speed,and CF content on the morphology and tensile properties of microcellular injection‐molded CF/PP composites

Carbon fiber/polypropylene composite foams were prepared by microcellular injection molding using nitrogen as a foaming agent. The effects of nitrogen content, injection speed, and CF content on the morphology and tensile properties of the composite foams were investigated. A three‐layer structure was formed in the microcellular foams: the skin layer was solid, the intermediate layer contained stretched cells parallel to the flow direction, and the core layer consisted of spherical cells. The average cell diameter of the machine direction decreased from 41 to 34 μm as the nitrogen content increased from 0.5 to 1 wt%, increased from 34 to 43 μm as the injection speed increased from 50 to 150 mm/s, and decreased from 34 to 25 μm as the CF content increased from 10 to 30 wt%. Thus, the microcellular structure was improved by increasing the nitrogen and CF content and by decreasing the injection speed. Furthermore, when the CF content increased from 10 to 30 wt%, the Young's modulus of the solids and foams increased by 78% and 113%, respectively. Thus, the Young's modulus of the foams improved by 35% due to the improvement in the cellular structure. POLYM. ENG. SCI., 59:1371–1380 2019. © 2019 Society of Plastics Engineers