道路一般部周辺における等価騒音レベルL_<Aeq>を, 音源(線音源放射)からの距離減衰に, 回折補正量α_d及地表面等種々の原因による補正量α_<i, eq>を加えることにより簡便に予測する計算法を提案した。補正量α_<i, eq>は, 実測値と予測値との整合を図るためのものであり, 本研究では, 数多くの実測データに基づいて設定されたASJ Model 1975の補正量α_iから間接的に求めている。この簡易計算法による予測値と, ASJ Model 1998のB法による予測値を種々の条件下で比較検討した。その結果, 両者の予測値に大差はなく, 道路一般部に対する簡易計算法の有用性が示された。

抄録全体を表示

This paper reports results of magnetic field measurements around power distribution equipment i.e. pad-mounted transformers, pad-mounted switchgears and vertical cables. Measurements were carried out in accordance with IEC 62110 which prescribes measurement and evaluation procedures of non-uniform as well as uniform magnetic fields generated by ac power systems with regard to public exposure. The average exposure level of magnetic field, corresponding to the spatial average over entire human body of magnetic field to which the individual is exposed, was evaluated for each power distribution equipment based on the measurement results. The maximum exposure level, the highest average exposure level over the area of interest, was also obtained. It was found that both exposure levels are much lower than the reference level from the ICNIRP Guidelines published in 2010.

抄録全体を表示

Resultant low frequency magnetic field generated was measured as a function of distance from them over broadband range (40-800Hz) and harmonic range (100-800Hz) on eleven kinds and more than two hundred recent household appliances in total. The relationship between magnetic filed measured and the power consumption of household appliances was also examined. As a result, it is verified that magnetic field from appliances is drastically reduced as the distance goes. And, any clear dependence of what on the power consumption of appliances is not recognized. Furthermore, from harmonic component analysis by using FFT for current flowing in appliances, it is assumed that relatively large amount of harmonic components with odd numbers is contained in the magnetic field.

抄録全体を表示

トンネルは時として音の伝搬を助長することが知られている。本稿では, そのメカニズムを説明するため, 音線理論と坑内におけるエネルギー収支を基に, 音の強さに関する伝搬式を導出し検討を行った。トンネルの存在がもたらす受音レベルの増加(挿入利得)は, トンネルの寸法(長さ, 断面積, 周長)及び内表面の平均吸音率を基に算定できることを示した。更に, 受音側の抗口周辺において, この利得(トンネル効果)の広がりについて考察を加えた。

抄録全体を表示