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Volume 65 (2003)
- Issue 6 Pages 511-
- Issue 5 Pages 441-
- Issue 4 Pages 365-
- Issue 3 Pages 189-
- Issue 2 Pages 117-
- Issue 1 Pages 3-
Volume 65, Issue 6
Displaying 1-4 of 4 articles from this issue
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Iwao TAKEI2003 Volume 65 Issue 6 Pages 511-522
Published: November 15, 2003
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSDielectric properties of snow samples, which were made from stored snow or hoar frost, were studied in the frequency range from 50 Hz to 5 MHz and temperature range from -15°C to -0.3°C. In the sintering process at -1°C, the dielectric dispersion strength and the low-frequency conductivity of snow samples increased with time. The sintering effects can be mainly related to the growth of bonds between ice particles. The dielectric-relaxation time of snow samples at -10°C was less than 1/10 the value for ice. A typical plot of the complex dielectric constant (Cole-Cole plot) showed a locus with a depressed shape on the high-frequency side, which reveals the distribution of relaxation times. The results of the dielectric dispersion suggest an easier reorientation of water molecules near the surface of ice particles. The low-frequency conduction, which reflects the d.c. conduction in snow samples, consists largely of surface conduction on the ice particles, and shows the influence of the quasi-liquid layer on the ice particles above -6°C. The temperature dependence of the low-frequency conductivity(e.g. at 100 Hz)of snow samples shows a peak around -2deg:C.View full abstractDownload PDF (16522K) -
Hirotada NANJO, Masumi KASAI2003 Volume 65 Issue 6 Pages 523-531
Published: November 15, 2003
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSWe have developed a snow-melting system using a reservoir and geothermal heat-exchanging well. It is not easy to melt a huge amount of snow using only geothermal energy, simply because the energy due to geothermal heat conduction is quite small. In order to overcome the shortcomings, we constructed an underground reservoir. The snow we put into the reservoir is melted gradually in the reservoir water, with the thermal energy supply from the geothermal heat-exchanging well. From the experimental data, we have obtained the following results. First, we have quantitatively clarified that the amount of the geothermal heat conduction from the underside of the reservoir is about 13 W/m2, and that only geothermal energy due to the heat conduction is not enough for the snow melting system. Second, we have estimated that the geothermal energy output is about 2.5 kW from a heat-exchanging well 100 mm in diameter and 30 m in depth, in the quasi-stationary state. Finally, we have shown that our system using a reservoir and a geothermal heat-exchanging well melt snow with high efficiency.View full abstractDownload PDF (8545K) -
compared with damage in a pure sugi-forestHideki OOHARA2003 Volume 65 Issue 6 Pages 533-541
Published: November 15, 2003
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSSnow accretion damage in a mixed forest with sugi and broad-leaved trees was compared with damage in a pure sugi-forest. The mixed forest suffered snow damage more severely than the nearby sugi-forest. Damaged trees in the mixed forest did not show the contagious distribution which was often observed in pure sugi-forests. Damage to sugi and broad-leaved trees increased as the individual height-diameter ratio increased in all stands. In each height-diameter ratio class, sugi trees in the mixed forest were more damaged than those in a pure sugi-forest. Sizes of damaged trees were biased to be smaller than those of non-damaged trees in the mixed forest. This characteristic was common to damage in coniferous forests after thinning or with gaps. Thus, a mixed forest is suggested to be in danger of snow accretion damage. The crown structure of the mixed forest containing deciduous trees, which permeates snow better than an evergreen crown, is similar to that of pure sugi-forests with gaps after thinning.View full abstractDownload PDF (5511K) -
Recent snow storm damage on the Pacific coast in the North Tohoku districtTakeharu BOKURA, Sinji HAYASI2003 Volume 65 Issue 6 Pages 543-550
Published: November 15, 2003
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESS
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