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101.
Tai Ho Choo Soo Kwon Chae Hyeon Cheol Yoon Yeon Moon Choo 《Environmental Earth Sciences》2014,71(2):675-683
Discharge is an important factor in river design for water utilization, water control and hydraulic structures; therefore, an accurate estimation of the discharge is required. At present, a rating curve depicting the relationship between a stage and discharge is used to calculate the discharge from river systems. Although the rating curve has an advantage in that it can predict and use the discharge during the flood season in which the measurement is difficult, there is room for improvement as it does not reflect the hydraulic characteristics of rivers. Therefore, in this study, discharge was predicted using the convenient calculation method with empirical mediating variables of the Manning and Chezy equations which were proposed by the author’s previous research as a new methodology for estimating discharge in an open channel. This was proven, based on the data measured in a meandering open channel system in a lab at the Mississippi River in the US and at the Columbia Del Dique Canal, and an accuracy level at a coefficient of 0.8 was demonstrated. Thus, this method, which reflects the hydraulic characteristics and predicts the discharge in a simple manner, is expected to be convenient in practice. 相似文献
102.
Byung Sun Lee Sung-Ho Song Jin Sung Kim Jae Yeon Um Kyoungphile Nam 《Environmental Earth Sciences》2014,71(4):1521-1532
This study was conducted to identify the availability of coastal groundwater discharge (CGD), subsurface fluids flowing from inland through the coastal area to sea, as an alternative water resource for a large-scale reclaimed land. The behaviors of stable isotopes indicated that groundwater originated from inland precipitation and traveled as CGD along the coast line. Most of the groundwater samples collected from domestic wells installed along the old coast line were considered to be relatively fresh from the correlation analysis among chemical constituents. The average electrical conductivity (EC) values of the samples were identified as averaging 1,125–1,297 μS cm?1, corresponding to appropriate crop growth. A weathered-rock layer in a small catchment within the reclaimed land was proved to be a main CGD pathway, with electrical resistivity anomalies ranging from 7 to 14 Ω m. Five monitoring wells were placed in this catchment to delineate the occurrence of CGD. Long-term vertical EC profiling results for the monitoring wells indicated that CGD occurs within a depth of 30 m below the ground surface. Annual monitoring data for groundwater level and EC demonstrated that the water quality of CGD was improved by introducing fresh terrestrial groundwater. A remarkable improvement in water quality (EC decrease of 900–1,600 μS cm?1) of CGD was observed during the saline water pumping test that explains how CGD could be an alternative water resource for the reclaimed land. 相似文献
103.
A low-complexity time-domain approach for global navigation satellite systems is proposed to detect and identify single-tone, multi-tone, swept continuous wave interference (CWI) and band-limited white Gaussian noise (BLWN). An adaptive notch filter and adaptive cascading filter structure are employed to identify the type of interference signals. The number of the cascading stages is selected by comparing the total power in receiver bandpass, and after, passing the adaptive notch filter. For this reason, the proposed filter structure is more efficient in identifying and mitigating interference signals than the conventional filter structure. In addition, the automatic gain control gain is used to detect the existence of continuous wave interference. The performance of the interference detection and identification method is evaluated for the cases of GPS signal in the presence of single-tone, multi-tone, swept CWI and BLWN. 相似文献
104.
Raymond F. Smith K. Thomas Lorenz Darwin Ho Bruce A. Remington Alex Hamza John Rogers Stephen Pollaine Seokwoo Jeon Yun-Suk Nam J. Kilkenny 《Astrophysics and Space Science》2007,307(1-3):269-272
In recently developed laser-driven shockless compression experiments an ablatively driven shock in a primary target is transformed
into a ramp compression wave in a secondary target via unloading followed by stagnation across an intermediate vacuum gap.
Current limitations on the achievable peak longitudinal stresses are limited by the ability of shaping the temporal profile
of the ramp compression pulse. We report on new techniques using graded density reservoirs for shaping the loading profile
and extending these techniques to high peak pressures. 相似文献
105.
M. Favre J. Moreno H. Chuaqui E. Wyndham M. Zambra P. Choi C. Dumitrescu-Zoita 《Astrophysics and Space Science》1997,256(1-2):337-342
Discharge formation in the A–K space of transient hollow cathode discharge (THCD) is causally linked with the emission of high energy electron beams originating in the hollow cathode region (HCR). Ionization in the A–K gap proceeds through the formation of a moving virtual anode, whose time evolution is strongly correlated with different periods in the electron beam activity. Here, we report on time and space resolved observations of different ionization events inside the HCR, which are time correlated with ionization processes inside the A–K gap. The experiments have been performed in Hydrogen, at pressures between 50 and 400 mTorr. A statistical study of the characteristic times associated with the different ionization events, based on von Laue plots, shows that the time distribution of events is well described by a single Gaussian distribution. 相似文献
106.
Yu-Li Wang Liang-Cheng Chang Fei Liu Yen-Te Ho Tzu Bin Wang Tian-Chyi Jim Yeh Jui-Pin Tsai 《Ground water》2022,60(4):518-529
Groundwater responses measured from multiple wells at different depths are essential for delineating the aquifer heterogeneity using hydraulic tomography (HT). In general, conducting HT requires many wells because traditional well monitoring is usually partially open at a specific depth interval or is fully penetrating. Accordingly, conducting an HT survey is typically costly and time-consuming. To tackle these issues, a new multi-level monitoring system (MLMS) for the HT survey was developed using the fiber Bragg grating (FBG) technique. This FBG MLMS could collect the depth-discrete groundwater observations from a fully penetrated 2-inch well. Three field campaigns were conducted to validate the capability of the FBG MLMS for HT surveys. The results show that the accuracy and stability of this MLMS are reliable and that FBG MLMS is beneficial for conducting an HT survey. Specifically, compared to the traditional monitoring well in an injection event, this FBG MLMS can concurrently cause an increase in the number of cross-hole tests several times and collect many more head observations than the standard methods, resulting in the observed flow fields efficiently reaching ergodic conditions and effectively improving the accuracy of the estimated hydraulic heterogeneity. Therefore, the FBG MLMS could be an alternative MLMS for efficiently and economically conducting an HT survey. 相似文献
107.
Wang Lingping Song Dongri Zhou Gordon G. D. Chen Xiao Qing Xu Min Choi Clarence E. Peng Peng 《Landslides》2022,19(8):1881-1896
Landslides - The multiple-barrier mitigation strategy in the debris-flow source area is an effective approach to inhibit debris-flow entrainment and scale amplification along the flow path.... 相似文献
108.
Acta Geotechnica - Granular impact—the dynamic intrusion of solid objects into granular media—is widespread across scientific and engineering applications including geotechnics.... 相似文献
109.
On a novel approach to forecast sparse rare events: applications to Parkfield earthquake prediction 总被引:1,自引:1,他引:0
Natural Hazards - Rare events are plentiful in nature and most of them have devastating consequences on human lives and property. Modeling such events is intrinsically challenging due to their very... 相似文献