排序方式： 共有41条查询结果，搜索用时 15 毫秒
1.
The thermodynamic structure on top of a numerically simulated severe storm is examined to explain the satellite observed plume formation above thunderstorm anvils. The same mechanism also explains the formation of jumping cirrus observed by Fujita on board of a research aircraft. A three-dimensional, non-hydrostatic cloud model is used to perform numerical simulation of a supercell that occurred in Montana in 1981. Analysis of the model results shows that both the plume and the jumping cirrus phenomena are produced by the high instability and breaking of the gravity waves excited by the strong convection inside the storm. These mechanisms dramatically enhance the turbulent diffusion process and cause some moisture to detach from the storm cloud and jump into the stratosphere. The thermodynamic structure in terms of the potential temperature isotherms above the simulated thunderstorm is examined to reveal the instability and wave breaking structure. The plumes and jumping cirrus phenomena represent an irreversible transport mechanism of materials from the troposphere to the stratosphere that may have global climatic implications. 相似文献
2.
This work develops a top‐down modelling approach for storm‐event rainfall–runoff model calibration at unmeasured sites in Taiwan. Twenty‐six storm events occurring in seven sub‐catchments in the Kao‐Ping River provided the analytical data set. Regional formulas for three important features of a streamflow hydrograph, i.e. time to peak, peak flow, and total runoff volume, were developed via the characteristics of storm event and catchment using multivariate regression analysis. Validation of the regional formulas demonstrates that they reasonably predict the three features of a streamflow hydrograph at ungauged sites. All of the sub‐catchments in the study area were then adopted as ungauged areas, and the three streamflow hydrograph features were calculated by the regional formulas and substituted into the fuzzy multi‐objective function for rainfall–runoff model calibration. Calibration results show that the proposed approach can effectively simulate the streamflow hydrographs at the ungauged sites. The simulated hydrographs more closely resemble observed hydrographs than hydrographs synthesized using the Soil Conservation Service (SCS) dimensionless unit hydrograph method, a conventional method for hydrograph estimation at ungauged sites in Taiwan. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
This study investigates the impact of climate change on rainfall, evapotranspiration, and discharge in northern Taiwan. The upstream catchment of the Shihmen reservoir in northern Taiwan was chosen as the study area. Both observed discharge and soil moisture were simultaneously adopted to optimize the HBV‐based hydrological model, clearly improving the simulation of the soil moisture. The delta change of monthly temperature and precipitation from the grid cell of GCMs (General Circulation Models) that is closest to the study area were utilized to generate the daily rainfall and temperature series based on a weather generating model. The daily rainfall and temperature series were further inputted into the calibrated hydrological model to project the hydrological variables. The studies show that rainfall and discharge will be increased during the wet season (May to October) and decreased during the dry season (November to April of the following year). Evapotranspiration will be increased in the whole year except in November and December. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
4.
Three methods, Shuffled Complex Evolution (SCE), Simple Genetic Algorithm (SGA) and Micro‐Genetic Algorithm (µGA), are applied in parameter calibration of a grid‐based distributed rainfall–runoff model (GBDM) and compared by their performances. Ten and four historical storm events in the Yan‐Shui Creek catchment, Taiwan, provide the database for model calibration and verification, respectively. The study reveals that the SCE, SGA and µGA have close calibration results, and none of them are superior with respect to all the performance measures, i.e. the errors of time to peak, peak discharge and the total runoff volume, etc. The performances of the GBDM for the verification events are slightly worse than those in the calibration events, but still quite satisfactory. Among the three methods, the SCE seems to be more robust than the other two approaches because of the smallest influence of different initial random number seeds on calibrated model parameters, and has the best performance of verification with a relatively small number of calibration events. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
5.
A thin‐profile buckling‐restrained brace (thin‐BRB) consists of a rectangular steel casing and a flat steel core that is parallel to a gusset plate. A thin configuration reduces the width of the restraining member and thus saves usable space in buildings. However, deformable debonding layers, which cover the steel core plate in order to mitigate the difference between the peak tensile and compressive axial forces, provide a space for the steel core to form high mode buckling waves when the thin‐BRB is under compression. The wave crests squeeze the debonding layers and produce outward forces on the inner surface of the restraining member. If the restraining member is too weak in sustaining the outward forces, local bulging failure occurs and the thin‐BRB loses its compression capacity immediately. In order to investigate local bulging behavior, a total of 22 thin‐BRB specimens with a ratio of steel core plate to restraining steel tube depth ranging from 0.3 to 0.7 and axial yield force capacities ranging from 421 kN to 3036 kN were tested by applying either cyclically increasing, decreasing, or constant axial strains. The restraining steel tube widths of all the specimens were smaller than 200 mm and were infilled with mortar with a compressive strength of 97 MPa or 55 MPa. Thirteen of the 22 thin‐BRB specimens' restraining members bulged out when the compressive core strains exceeded 0.03. A seismic design method of the thin‐BRB in preventing local bulging failure is proposed in this study. Test and finite element model (FEM) analysis results suggest that the outward forces can be estimated according to the BRB compressive strength, steel core high mode buckling wavelength, and the debonding layer thickness. In addition, the capacity of the restraining member in resisting the outward forces can be estimated by using the upper bound theory in plastic analysis. Both the FEM analysis and test results indicate that the proposed method is effective in predicting the possibility of local bulging failure. Test results indicate that the proposed design method is conservative for thin‐BRB specimens with a large steel core plate to restraining steel tube depth ratio. This paper concludes with design recommendations for thin‐BRBs for severe seismic services. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Abstract This study investigates the characteristics of hydrograph components from a watershed in Taiwan. Hydrograph components were modelled by using a model of three serial reservoirs with one parallel reservoir. Mean rainfall was calculated by using the block kriging method. The model parameters for 38 events were calibrated by using the shuffled complex evolution optimization algorithm. The model verification was made using 18 events. Based on the study results, the following findings were obtained: (1) for single-peak events, times to peak of hydrograph components are an increasing power function of the peak time of rainfall; (2) peak discharges of hydrograph components are linearly proportional to that of total runoff, and the ratios of quick and slow runoff are approximately 83% and 17% of total runoff, respectively; and (3) the total volume of quick runoff component is 52% of total runoff and that of slow runoff is 27%. Editor D. Koutsoyiannis Citation Li, Y.-J., Cheng, S.-J. Pao, T.-L. and Bi, Y.-J., 2012. Relating hydrograph components to rainfall and streamflow: a case study from northern Taiwan. Hydrological Sciences Journal, 57 (5), 861–877. 相似文献
7.
Mucins are important components of mucus,which form a natural,physical,biochemical and semipermeable mucosal layer on the epidermis of fish gills,skin,and the gastrointestinal tract. As the first step towards characterizing the function of Muc2,we cloned a partial Megalobrama amblycephala Muc2 cDNA of 2 175 bp,and analyzed its tissue-specific expression pattern by quantitative real-time PCR(qPCR). The obtained sequence comprised 41 bp 5′-untranslated region(5′-UTR),2 134 bp open reading frame encoding a protein of 711 amino acids. BLAST searching and phylogenetic analysis showed that the predicted protein contained several common secreted mucin-module domains(VWD-C8-TIL-VWD-C8) and had high homology with mucins from other vertebrates. Among four candidate reference genes(β- Actin,RPI13α,RPII,18S) for the qPCR,R PII was chosen as an appropriate reference gene because of its lowest variation in different tissues. M. amblycephala Muc2 was mainly expressed in the intestine,in the order(highest to lowest) middle-intestine fore-intestine hind-intestine. Muc2 was expressed relatively poorly in other organs(brain,liver,kidney,spleen,skin and gill). Furthermore,after 20-days of starvation,M. amblycephala Muc2 expressions after refeeding for 0h,3 h,16 h,3 d,and 10 d were significantly decreased in the three intestinal segments(P 0.05) at 16 h,and were then upregulated to near the initial level at 10 d. 相似文献
8.
大气校正对SPOT卫星遥测水质的影响 总被引：1，自引：0，他引：1
藉由卫星遥测进行河川水质监测，目前尚没有较明确可行之方法，如何利用较为简单且适当的SPOT卫星遥测大气校正方法，正确辨识水体水质，是本研究的主要目的。利用SPOT卫星作两阶段非监督式及监督式自动分类，确认卫星影像中水质测站对应之水体样本，并将所有样本依季节分群，俾让卫星监测水体水质样本较为均质。模拟方式采用多变量回归、类神经网络及判别分析3种模式，并比较4种不同之大气校正程序。结果发现。以水质及其指标整体预测来看，类神经网络预测结果较优于多变量回归及判别分析的结果，大气校正方法以直接采用灰度值并消除最暗像元灰度值之校正方法，即可达到不错之预测结果。综合而言，以SPOT或分辨率更高之卫星光谱遥测水质是简单可行，但仍需更多数据以验证其精确度。 相似文献
9.
10.
A comparative modelling of two catchments of similar sizes in Taiwan and England is described. In the study, despite its success in many Taiwanese catchments, including the Yan‐Shui Creek catchment in this study, the distributed model GBDM was initially found unsuitable when applied to the Brue catchment in South West England. However, the simulations are much better after revising the infiltration capacity. Further exploration reveals several interesting findings. (1) The infiltration computation based on soil characteristics and classifications is unreliable in the model. Other factors, such as climate, farming practice and vegetation cover, could have a much more significant impact. (2) The application of the GBDM far away from its ‘home country’ unveils a possible weakness of such a model for being ‘underfitting’. The fact that an ‘adjustment factor’ added in the model could improve both its calibration and validation may indicate that there is a room to improve the GBDM structure for catchments outside Taiwan. (3) The study illustrates the difficulty in creating a universal distributed model that could suit all possible hydrological environments, under the constraint of model parameter parsimony to minimize the ‘equifinality’ problem. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献