JEMEA（日本電磁波エネルギー応用学会）が2006年8月に発足してから14年が経過し、学会主催のシンポジウム、研究会、各種イベントが数多く開催されてきました。歴代理事長も5人目となり、今までのアカデミックからではなく、今回初めての民間企業出身（2020.3までに在籍）となります。

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技術的な点はＷＧの責任者である福島氏の記事に詳しいので、本稿ではＤＢ開発の企画から運用に至るまでに行われた議論について回想録風に紹介する。また本データベースの操作手順を表す。最後に本データベースが日本におけるマイクロ波研究にとって真の意味での knowledge base になるための要件を明らかにする。

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  The relationship among interior shrinkage, exterior shrinkage and porosity in conical castings for JIS D12S secondary alloy was investigated in comparison with virgin alloy. The gas contents in the melt were measured by the vacuum fusion extraction method. The relation between expansion and pore generation was also examined to investigate the rise of bottom interior shrinkage cavity observed in high porosity castings. In both secondary and virgin alloys, exterior shrinkage remains constant and interior shrinkage reduces for the increase in porosity. The porosity increases linearly with a gas content in the melt. However, in some secondary alloys different porosities are observed even with the same gas content. The expansion occurs at the initial stage of solidification. This expansion is observed, as well as in some Al-Si binary alloys. Many pores are observed to be uniformly distributed in the entire of the castings. Microstructure of the expansion part shows much more eutectic phases than any other parts. In the case of the solidification under pressurized atmosphere, expansion does not occur and porosity is low in spite of high gas content. These results show that such an expansion may be due to the residual melt pushed upwards by pore generation as the solidification advances.

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  The surface sink, part of the exterior shrinkage in conical castings of Al-4 % Si and Al-7 % Si alloys was studied in relation to the formation process of the interior shrinkage. The point of time of pore generation was estimated by measurement of the density of small ingots quenched from various temperatures during cooling. The porosity increases linearly with an increase in gas content in the melt. With an increase in porosity, the surface sink decreases at lower porosity levels, but it remains almost constant at higher porosity levels. The interior shrinkage terminates by the initial stage of the primary crystal solidification. The surface sink occurs at the same time of the interior shrinkage termination or just after that. Most of pores are formed by the initial stage of the primary crystal solidification. An unchanged volume of interior shrinkage with an increase in porosity at lower porosity levels may be due to little effect of pore generation on interior shrinkage formation because of the low gas content. The decreases in exterior shrinkage at lower porosity level and in the interior shrinkage at higher porosity level with an increse in porosity may be due to the apparent substitution of pore hole for solidification shrinkage.

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2016 年より始まった若手サマースクールを、2019年度は、9月17日、18日の2日間に岡山県で開催された。過去の開催例（2016年、岐阜県奥飛騨、2017年長野県軽井沢、2018年宮城県松島）にならい温泉地（岡山県湯郷温泉）での開催を行った。開催に当たり、講師を快く引き受けていただきました広島大学 深澤智典先生、岡山大学 仁科勇太先生、㈱福島英沖先生に感謝いたします。参加者は、19名と例年とほぼ同じ程度の人数が集まりました。他の関連学会と重なり、日程調整が大変になるなど多忙の中、参加者19名（うち学生4名）になり、ほとんどが遠方よりの移動にもかかわらず、参加者のみなさまには御礼申し上げます。

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  Relation between the fluidity and the pressure transferred from a pouring cup during solidification of Al-Si alloys was investigated. The fluidity length of Al-Si alloys is minimum around the portion with 6 % Si and it increases with increasing Si content. Particularly, hypereutectic alloys are excellent in fluidity. They have a good fluidity in the semi-solid state containing primary Si as well as in a liquid state. The effect of the Si content on the fluidity is remarkable for a pressurized gating system and less remarkable for an unpressurized gating system. For 6 % Si alloys, the pressure transmittance of the metal head from the pouring cup fails at the early stage of primary solidification. For alloys with more than 11 % Si, however, pressure is transferred until the middle stage of eutectic solidification. Namely, when the solidification manner changes from a mushy type to a skin-formation type with increasing Si content, liquid remains in the central part until the final stage of solidification. As a result, the duration of pressure transmittance becomes larger, extending the fluidity length.

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  A computer system for analyzing the molten metal flow in die cavity of a plate shaped die castings has been developed. The molten metal flow in the die cavity was simulated by solving reformed 2D Navier-Stokes equations considering the thickness of the flow. The apparent kinematic viscosity of the actual flow in the simulation, 2cm²/s which conformed to the actual flow was obtained. With the simulation system using this coefficient, the molten metal flow in the die cavity of the plate shaped die castings having the gas defects was analyzed, enabling the decrease of the defects.

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  Dispersed porosities in Sr-modified Al-Si Alloy castings were examined.
  Even if Sr is added to molten metal containing oxide inclusions before vacuum degassing, the hydrogen content in the molten metal does not decrease, resulting in dispersed porosities in the castings.
  On the other hand, when molten metal without oxide inclusion is degassed in a vacuum after Sr addition, no dispersed porosity is found. To produce porosity free castings, therefore, it is necessary to eliminate oxide inclusions from the molten metal before Sr addition and vacuum degassing.
  Sr has no influence on the feeding ability of Al-Si alloys.

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