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51.
Comparison of the Bright Band Characteristics Measured by Micro Rain Radar (MRR) at a Mountain and a Coastal Site in South Korea 总被引:1,自引:0,他引:1
Data from a long term measurement of Micro Rain Radar (MRR) at a mountain site (Daegwallyeong,DG, one year period of 2005) and a coastal site (Haenam, HN, three years 2004–2006) in South Korea were analyzed to compare the MRR measured bright band characteristics of stratiform precipitation at the two sites. On average, the bright band was somewhat thicker and the sharpness (average gradient of reflectivity above and below the reflectivity peak) was slightly weaker at DG, compared to those values at HN. The ... 相似文献
52.
53.
Kangseok Hwang Eun-A Yoon Sukyung Kang Hyungkee Cha Kyounghoon Lee 《Ocean Science Journal》2017,52(4):563-571
The present study focuses on the influence of target strength (TS) changes in the swimming angle of the hairtail (Trichiurus lepturus). We measured in-situ TS at 38 and 120 kHz with luring lamps at a fishing ground for jigging boats near the coastal waters of Jeju-do in Korea. Swimming angle and size of hairtails were measured using an acoustic camera. Results showed that mean preanal length was estimated to be 13.5 cm (SD = 2.7 cm) and mean swimming tilt angle was estimated to be 43.9° (SD = 17.6°). The mean TS values were ?35.7 and ?41.2 dB at 38 and 120 kHz, respectively. The results will assist in understanding the influence of swimming angle on the TS of hairtails and, thus, improve the accuracy of biomass estimates. 相似文献
54.
Satellite observations of sea level anomalies(SLA) from January 1993 to December 2012 are used to investigate the interannual to decadal changes of the boreal spring high SLA in the western South China Sea(SCS) using the Empirical Orthogonal Function(EOF) method. We find that the SLA variability has two dominant modes. The Sea Level Changing Mode(SLCM) occurs mainly during La Ni?a years, with high SLA extension from west of Luzon to the eastern coast of Vietnam along the central basin of the SCS, and is likely induced by the increment of the ocean heat content. The Anticyclonic Eddy Mode(AEM) occurs mainly during El Ni?o years and appears to be triggered by the negative wind curl anomalies within the central SCS. In addition, the spring high SLA in the western SCS experienced a quasi-decadal change during 1993–2012; in other words, the AEM predominated during 1993–1998 and 2002–2005, while the La Ni?a-related SLCM prevailed during 1999–2001 and 2006–2012. Moreover, we suggest that the accelerated sea level rise in the SCS during 2005–2012 makes the SLCM the leading mode over the past two decades. 相似文献
55.
We observed the spectrum of 44i Boo in 1981 March and in 1983 March. We found that the equivalent widths of the CaII K and CaI 4227 A lines showed periodic variations with different phases, and that the profile of the Hα line also varied in step. A preliminary analysis is made based on our observations and the recent IUE data and a simple model atmosphere with stellar activity of 44i Boo (B) is proposed. 相似文献
56.
M. Chaâbane M. Masmoudi K. Medhioub F. Elleuch 《Meteorology and Atmospheric Physics》2006,92(1-2):103-114
Summary Spectral aerosol optical thickness have been measured at Thala site (central West of Tunisia) from March to October 2001.
The measurement site is located in a continental and non industrialized region, approximately 150 km from the North coast
of the Mediterranean Sea and nearby the Algerian border. Thala site could be then influenced by the dust content of the continental
air masses carried by western and southern winds. A second pollution source is constituted by industrial and/or maritime particles
carried by northern and eastern winds. AOT measurements acquired through the ground-based AERONET are analyzed. The diurnal
cycle over Thala and two other areas within the network showed various trends and a prevailing pattern of the optical thickness
increase by 10–40% during the day. Daily AOT and monthly averaged aerosol optical thickness, ?ngstr?m coefficient and precipitable
water vapor are computed and compared with those of other sites. Measured meteorological parameters represent a valuable supplement
to the data sets with the sunphotometer measurements. The analysis of the results shows that there is a high correlation between
aerosol optical properties (AOT and ?ngstr?m coefficient) and the local weather conditions, essentially wind speed and direction
and air specific humidity. 相似文献
57.
Sung-Soo Cha Jin-Yong Lee Dae-Hyuck Lee Eric Amantini Kang-Kun Lee 《Engineering Geology》2006,84(3-4):229-243
Feasibility of storing LNG in a lined rock cavern was evaluated using a pilot cryogenic rock cavern constructed in Daejeon, Korea. The pilot program included hydrogeological and engineering characterization of the rock mass around the cavern, design and construction of a drainage system, and pilot operation of the cryogenic cavern. An appropriate drainage system is most important to protect the containment system of LNG from thermal shocks due to ice lenses and hydrostatic pressure of groundwater. As a part of the pilot program, this study focused on the evaluation of hydraulic and engineering properties of the rock mass around the cavern. For this purpose, engineering logging of the rock cores, single and cross-hole hydraulic tests, and recharge/drainage tests were performed using seven drilled holes with different trends and plunges. Three main joint sets were found from the logging of the rock cores, acoustic borehole televiewer, and window mapping. The orientations of the three major joint sets were 60/209, 40/171, and 29/331, which can provide the main groundwater flow paths. Mean RQD values ranged from 56 to 88, which were classified as fair and good, although varying with depth along single boreholes. Hydraulic conductivity from the single and cross-hole hydraulic tests estimated in the order of 10−6 or 10−7 m/s and corresponding transmissivity ranged between 10−5 and 10−6 m2/s. Permeable intervals identified from the hydraulic tests were mostly located above the cavern roof. Below the roof, the permeable zone was difficult to observe. According to the hydraulic communication tests performed for some designated intervals, hydraulic connection between boreholes was highly varied with depth or location, which indicated a very different distribution of water conducting joint sets along the boreholes. When water was injected at R1 with constant or varying flow rates, monotonous and stable seepage was observed at observation boreholes. From this, some stable drainage was expected even in relatively heavy rainfalls. When designing the drainage system of the cavern, the drainage holes should be orientated to maximize frequency of encountering the major joint sets and the permeable intervals identified from this study. 相似文献
58.
Liu Xue-fu Peng Song-chuan Cha Guang-wei LI Xiao-yu 《Chinese Astronomy and Astrophysics》1985,9(4):296-299
We give results of photoelectric photometry and spectral observations of Aur during its 1982–1984 ingress and total eclipse. Narrow-band light curves and variations in radial velocity within a night resulting from autoregression analysis all indicate short time scale variations in the F supergiant primary on the order of hours or fractions thereof. Fluctuations with an amplitude of ±25 Km/s and a period of 400 d appear to be present in the measured radial velocity of the primary during ingress and totality. Obvious changes in the H profile were also observed: around the second contact of the total eclipse, there was emission in the blue wing; while around the third contact of the atmosphere eclipse, there was emission in the red wing. 相似文献
59.
Myung Hoon Kim Yunseok Choi Young Ho Cha Changsoo Shin 《Pure and Applied Geophysics》2009,166(12):1967-1985
In order to correctly interpret marine exploration data, which contain many elastic signals such as S waves, surface waves and converted waves, we have developed both a frequency-domain modeling algorithm for acoustic-elastic coupled media with an irregular interface, and the corresponding waveform inversion algorithm. By applying the continuity condition between acoustic (fluid) and elastic (solid) media, wave propagation can be properly simulated throughout the coupled domain. The arbitrary interface is represented by tessellating square and triangular finite elements. Although the resulting complex impedance matrix generated by finite element methods for the acoustic-elastic coupled wave equation is asymmetric, we can exploit the usual back-propagation algorithm used in the frequency domain through modern sparse matrix technology. By running numerical experiments on a synthetic model, we demonstrate that our inversion algorithm can successfully recover P- and S-wave velocity and density models from marine exploration data (pressure data only). 相似文献
60.
Seismic retrofit of MRF buildings using decentralized semi‐active control for multi‐target performances
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Numerous structures have been designed and built without taking earthquake ground motions or outdated seismic design codes into account. In order to improve the seismic performance of existing structures, many retrofit approaches based on performance‐based design have been developed. However, some of these approaches are inapplicable due to structural limitations or because they were developed with the assumption of single‐degree‐of‐freedom, which does not take higher modes into account. To overcome the limitations of these traditional methods, a multi‐performance‐based control design (MPBCD) methodology has been proposed by integrating a decentralized semi‐active control algorithm, magnetorheological dampers, and an advanced multi‐objective optimization method to provide various sets of retrofit control designs to satisfy multiple target performances under multiple seismic intensities without changing structural cross‐section sizes or material properties. This MPBCD method provides engineers with numerous sets of control designs (i.e., control device layouts with control design parameters) to help them select proper control designs to retrofit existing building structures and improve seismic performance. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献