The high mountains of Hindu-Kush Karakoram and Himalaya(HKKH) contain a large volume of snow and ice, which are the primary sources of water for the entire mountainous population of HKKH. Thus, knowledge of these avai...The high mountains of Hindu-Kush Karakoram and Himalaya(HKKH) contain a large volume of snow and ice, which are the primary sources of water for the entire mountainous population of HKKH. Thus, knowledge of these available resources is very important in relation to their sustainable use. A Modified Positive Degree Day Model was used to simulate daily discharge with the contribution of snow and ice melt from the Shigar River Basin, Central Karakoram, Pakistan. The basin covers an area of 6,921 km2 with an elevation range of 2,204 to 8,611 m a.s.l.. Forty percent of the total area is glaciated among which 20% is covered by debris and remaining 80% by clean ice and permanent snow. To simulate daily discharge, the entire basin was divided into 26 altitude belts. Remotely sensed land cover types are derived by classifying Landsat images of 2009. Daily temperature and precipitation from Skardu meteorological station is used to calibrate the glacio-hydrological model as an input variable after correlating data with the Shigar station data(r=0.88). Local temperature lapse rate of 0.0075 °C/m is used. 2 °C critical temperature is used to separate rain and snow from precipitation. The model is calibrated for 1988~1991 and validated for 1992~1997. The model shows a good Nash-Sutcliffe efficiency and volume difference in calibration(0.86% and 0.90%) and validation(0.78% and 6.85%). Contribution of snow and ice melt in discharge is 32.37% in calibration period and 33.01% is validation period. The model is also used to predict future hydrological regime up to 2099 by using CORDEX South Asia RCM considering RCP4.5 and RCP8.5 climate scenarios.Predicted future snow and ice melt contributions in both RCP4.5 and RCP8.5 are 36% and 37%, respectively. Temperature seems to be more sensitive as compared to other input variables, which is why the contribution of snow and ice in discharge varies significantly throughout the whole century.展开更多
A standard skill assessment （SA） tool was developed and implemented to evaluate the performance of op- erational forecast models in the Korea operational oceanographic system. The SA tool provided a robust way to as...A standard skill assessment （SA） tool was developed and implemented to evaluate the performance of op- erational forecast models in the Korea operational oceanographic system. The SA tool provided a robust way to assess model skill in the system by comparing predictions and observations, and involved the com- putation of multiple skill metrics including correlation and error skills. User- and system-based acceptance criteria of skill metrics were applied to determine whether predictions were acceptable for the system. To achieve this, the tool produced a time series comparison plot, a skill score table, and an advanced sum- marized diagram to effectively demonstrate the multiple skill scores. Moreover, the SA was conducted to evaluate both atmospheric and hydrodynamic forecast variables. For the atmospheric variables, acceptable error criteria were preferable to acceptable correlation criteria over short timescales, since the mean square error overwhelmed the observation variance. Conversely, for the hydrodynamic variables, acceptable root mean square percentage error （e.g., perms） criteria were preferable to acceptable error （e.g., erms） criteria owing to the spatially variable tidal intensity around the Korean Peninsula. Furthermore, the SA indicated that predetermined acceptance error criteria were appropriate to satisfy a target central frequency （fc） for which errors fell within the specified limits （i.e., the .fc equals 70%）.展开更多
Record-breaking high waves occurred during the passage of the typhoon Bolaven（1215）（TYB） in the East China Sea（ECS） and Yellow Sea（YS） although its intensity did not reach the level of a super typhoon.Winds an...Record-breaking high waves occurred during the passage of the typhoon Bolaven（1215）（TYB） in the East China Sea（ECS） and Yellow Sea（YS） although its intensity did not reach the level of a super typhoon.Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys.In order to understand how such high waves with long duration occurred,analyses have been made through measurement and numerical simulations.TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements.And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model.Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area.Thus the accuracy of simulations is considerably enhanced,and the computed results are also in better agreement with measured data than before.It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track.As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days,the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.展开更多
The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is det...The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons.Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon(2013), winter(2013), and pre-monsoon(2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors(DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of-20.81 °C/m, 4.05 °C/m, and-7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.展开更多
Whether groundwater resources can be sustainably utilized is largely determined and characterized by hydrogeological parameters.Estimating the groundwater recharge is one of the essential parameters for managing water...Whether groundwater resources can be sustainably utilized is largely determined and characterized by hydrogeological parameters.Estimating the groundwater recharge is one of the essential parameters for managing water resources and protecting water resources from contamination.This study researched the spatial and temporal variation of groundwater recharge in the Thepkasattri sub-district through integrating chloride mass balance(CMB)and water table fluctuation(WTF)methods.The chloride content of representative rainfall and groundwater samples was analyzed.Besides,WTF method was adopted from groundwater level data from 2012 to 2015.According to the CMB method,the mean recharge was estimated to be 1172 mm per year,accounting for 47%of the annual rainfall.Moreover,the estimated recharge from the WTF method took 26%of annual rainfall in 2015.The recharge was underestimated according to the WTF method,because of the uncertainty in specific yield estimates and the number of representative wells in the study area.Moreover,the correlation between rainfall and water table fluctuation data indicated the positive linear relationship between two parameters.The spatial recharge prediction indicated that recharge was higher(1200-1400 mm/yr)in the eastern and western catchment,while that in the central floodplains was between 800 mm/yr and 1100 mm/yr.In addition,low recharge value between 450 mm/yr and 800 mm/yr was observed in the south-west part of Thepkasattri.The spatial variation of recharge partly reflects the influences of land use and land cover of the study area.展开更多
The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing com...The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing components of the river discharge.This study examined and compared the hydrological responses in the glacier-dominated Shigar River basin(SRB)under various climatic scenarios using a semi-distributed Modified Positive Degree Day Model(MPDDM)and a distributed Glacio-hydrological Degree-day Model(GDM).Both glacio-hydrological models were calibrated and validated against the observed hydro-meteorological data from 1988–1992 and 1993–1997.Temperature and precipitation data from Shigar and Skardu meteorological stations were used along with field estimated degree-day factor,temperature,and precipitation gradients.The results from both models indicate that the snow and ice melt are vital contributors to sustain river flow in the catchment.However,MPDDM estimated 68%of rain and baseflow contribution to annual river runoff despite low precipitation during the summer monsoon,while GDM estimated 14%rain and baseflow contribution.Likewise,MPDDM calculated 32%,and GDM generated 86%of the annual river runoff from snow and ice melt.MPDDM simulated river discharge with 0.86 and 0.78 NSE for calibration and validation,respectively.Similarly,GDM simulated river discharge with improved accuracy of 0.87 for calibration and 0.84 NSE for the validation period.The snow and ice melt is significant in sustaining river flow in the SRB,and substantial changes in melt characteristics of snow and ice are expected to have severe consequences on seasonal water availability.Based on the sensitivity analysis,both models’outputs are highly sensitive to the variation in temperature.Furthermore,compared to MPDDM,GDM simulated considerable variation in the river discharge in climate scenarios,RCP4.5 and 8.5,mainly due to the higher sensitivity of GDM model outputs to temperature change.The integration of an updated melt module and two reservoir baseflow module in GDM is anticipated to advance the representation of hydrological components,unlike one reservoir baseflow module used separately in MPDDM.The restructured melt and baseflow modules in GDM have fundamentally enriched our perception of glacio-hydrological dynamics in the catchment.展开更多
Supraglacial debris is widely present on glaciers in alpine environments and its distribution greatly affects glacier melt.The present study aims to determine the effect of debris on glacier ice melt on Ponkar Glacier...Supraglacial debris is widely present on glaciers in alpine environments and its distribution greatly affects glacier melt.The present study aims to determine the effect of debris on glacier ice melt on Ponkar Glacier,Manang District,Nepal.We estimated ice melt under various debris thickness using Energy Balance(EB)model and conductive heat flux methods,which are compared with in-situ observations.Four stakes are installed on the glacier at different debris thickness of 11−40 cm.Meteorological data from March 2016 to May 2018 are obtained from the Automatic Weather Station(AWS)installed on the glacier surface at an elevation of 3,881 m a.s.l.for the energy balance calculation.Debris surface temperature and different debris depths are also measured on the glacier.The calculated ablation rates from the conductive heat flux method are 0.9,1.62 and 0.41 cm/d on pre-monsoon,monsoon and post-monsoon,respectively,with mean debris thermal conductivity 1.04 W/(m∙K).The net radiation shows little variation between the seasons,while turbulent heat flux varies in the season.Sensible heat flux was found to be highest in post-monsoon season due to a larger temperature gradient between surface and air.展开更多
Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the r...Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the region has very high tidal ranges over very gentle tidal flats, which is a very vulnerable region. Although the various remote sensing platforms can be used to map shoreline changes, the spatial and temporal resolutions are not enough to obtain it for a short time. Accordingly, in this study we introduce the newly developed low altitude Helikite remote sensing platform to achieve much better resolutions of shorelines and a bathymetry. The Helikite stands for Helium balloon and Kite, which is a kind of aerial platform that uses the advantages of both a Helium balloon and a kite. Field experiments were conducted in the Jaebu Island, off the coast of the west Korean Peninsula in January 29, 2011. In order to extract shorelines from the consecutive images taken by the low altitude Helikite remote sensing platform, active contours without edges （ACWE） is used. Edges or boundaries exist primarily on places between one type of objective and the other. Since the hydrodynamic pressure has an effect everywhere, the locations of the waterlines can be the isobath lines. We could map several waterlines, which would enable us to complete a local bathymetry map ranges from 35 to 60 cm depth. The error resulting from applying ACWE algorithm to the imagery to determine the waterline is approximately less than 1 m. Therefore, it is very unique way to obtain such high resolutions of bathymetry with high accuracy for the regions of extremely high tidal ranges for a short time.展开更多
The resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te has been measured by the superconducting quantum interference device magnetometer in the temperature range from 5 to 200 K under the appl...The resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te has been measured by the superconducting quantum interference device magnetometer in the temperature range from 5 to 200 K under the applied magnetic field of 1, 2, 4 and 6.5 Tesla, respectively, compared with that of no-magnetic field. The results show that the resistivity increases with increase applied magnetic field at higher temperature from 80 to 200 K, but decreases at lower temperature from 5 to 25 K. There exists a transitive range from 25 to 80 K, where the variation of the resistivity shows different tendencies depending on the strength of magnetic field. Maximum difference of resistivity under 6.5 Tesla from that without magnetic field in the temperature range from 30 to 200 K is only about 5 Ω·cm, but it increases up to 3 orders of magnitude at 5 K. The analysis shows that the variation of resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te under the magnetic field is the algebraic sum of the transverse direction magnetoresistance effect and the sp-d exchange interaction effect. TDRME plays major role in the high temperature range. However, with the decrease of temperature, the effect of sp-d EI on the resistivity gradually exceeds that of the transverse direction magnetoresistance effect through the transitive range, and becomes the dominant effect in the temperature range from 5 to 25 K, which leads to the dramatic decrease of resistivity.展开更多
A three-dimensional numerical tsunami model is developed to analyze the nonlinear behavior of flow around obstacles with the Marker and Cell （MAC） method based on the Navier-Stokes equations. Tnrough a comparison wi...A three-dimensional numerical tsunami model is developed to analyze the nonlinear behavior of flow around obstacles with the Marker and Cell （MAC） method based on the Navier-Stokes equations. Tnrough a comparison with experimental data for the cases of dam break and solitary wave propagation, verification of the three-dimensional numerical model is given. Numerical experiment is performed for the analysis of the nonlinear behavior of flow around obstacles and compared with experimental data. The velocity and pressure around obstacles are presented with sufficient accuracy for tstmami propagation passing through an obstacle.展开更多
This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling...This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling day using the Depth Integration Technique (DIT) on daily basis in the monsoon season, weekly in the pre- and post-monsoon seasons and bi-monthly in the winter season. Suspended sediment concentration (SSC) is calculated from the water samples using filtration followed by oven-drying, and a rating curve is used to calculate daily discharge of the Langtang River. The annual sediment yield is 109,276.75 tons and 37.69, 11.52 and 5.54 tons of sediment is transported per day in the pre-monsoon, post-monsoon and winter seasons, respectively. There is a very high value of 872.86 tons per day in the monsoon season, which contributes the highest sediment load among all of the seasons comprising 83% of the total sediment transport. Diurnal cycle of sediment discharge is clearly seen with higher sediment discharge during the evening than the morning and reaching maximum values of 41.1 kg·s<sup>-1</sup> and 61.5 kg·s<sup>-1</sup>, respectively. A clock-wise hysteresis loop has been obtained for discharge and sediment discharge where sediment flux is higher in the early monsoon than in the late monsoon for a corresponding discharge.展开更多
This study was conducted to clarify the food compositions of Corbicula bivalves (C. japonica and leana) in tidal rivers with varied landscapes. In order to grasp their trophic structures, we measured the carbon and ni...This study was conducted to clarify the food compositions of Corbicula bivalves (C. japonica and leana) in tidal rivers with varied landscapes. In order to grasp their trophic structures, we measured the carbon and nitrogen stable isotope ratios of the collected samples such as the bivalves with varied growth stages and the suspended particulate organic matters (SPOMs) with varied landscapes as their food sources, and then analyzed their relationships with IsoSource mixing model software. The stable isotope ratio measurements clarified that there was a large difference in the ranges of C. japonica and leana in spite of the same sampling locations, and the IsoSource analysis could quantitatively describe their food compositions. According to the results, it could be clarified that the variations in food compositions were dependent not only on the species difference but also on their growth stages. Furthermore, it might suggest that their diet preferences affected the spatial distributions of these Corbicula bivalves in this location.展开更多
During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment（TSS） can be used...During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment（TSS） can be used as an excellent tracer for Changjiang Diluted Water（CDW）. To analyze the spatial and temporal variations of the CDW distribution, the monthly mean TSS from Moderate Resolution Imaging Spectroradiometer（MODIS） ocean color data are constructed and are converted to salinity using the relationship between salinity observed from AQUARIUS and TSS. The process produces the detailed horizontal distribution of salinity with very high resolution（1 km）. From monthly mean salinity map from 2002 to 2012 in July and August, the expansion patterns of CDW are analyzed. The southerly wind in July and southeasterly wind in August transport the CDW eastward and northeastward, respectively. It is found that the yearly variation of the expansion of CDW toward the southern sea area of Korea is mostly due to the variation of southerly wind and the fluctuations of fresh water discharge into the Changjiang estuary show relatively little impact on the eastward extend of CDW. When 11-year mean（from2002 to 2012） salinity map in August is compared with World Ocean Atlas 2013, it is revealed that wind in August strengthened six times from 1994 and it causes the expansion of CDW extended 150 km further eastward.展开更多
The magnetization of Hg0.89Mn0.11 Te single crystal grown by vertical Bridgman method was studied by using superconducting quantum interference device magnetometer（SQUID Magnetometer）. First, magnetization measureme...The magnetization of Hg0.89Mn0.11 Te single crystal grown by vertical Bridgman method was studied by using superconducting quantum interference device magnetometer（SQUID Magnetometer）. First, magnetization measurements were done under various magnetic fi eld strengths from-20 kOe to 20 kOe at 5 K, 15 K, and 77 K, respectively. Then, the magnetizations were measured with continuous changes of temperature in the range from 5 K to 300 K under the magnetic field of 0.1 kOe and 10 kOe, respectively. The modifi ed Brillouin function was well fitted with the data of magnetization vs. magnetic field strength. The analysis indicated that there was an antiferromagnetic exchange coupling among Mn^2＋ ions. The results of reciprocal susceptibility vs. temperature fi t Curie-Weiss law very well at the temperatures above 40 K, but deviate from the law from 5 Kto 40 K, which shows that the antiferromagnetic exchange coupling among Mn^2＋ ions increases in the lower temperature range below 40 K. The experimental result was explained by extending higher-order terms in the calculation of susceptibility and fitted by a power law function. The measurements reveal that Hg0.89Mn0.11 Te possesses paramagnetic properties at temperatures from 5 K to 300 K.展开更多
Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of...Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide（a.k.a algal bloom） model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%–50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly required.As opposed to the bioassay data, it is necessary because the bioassay data have limitations in terms of the in-situ coastal conditions.展开更多
Rock slope kinematic analysis and rock mass classifications has been conducted at the 17^(th) km to 26^(th) km of USAID(United States Agency for International Development)highway in Indonesia.This research aimed to ex...Rock slope kinematic analysis and rock mass classifications has been conducted at the 17^(th) km to 26^(th) km of USAID(United States Agency for International Development)highway in Indonesia.This research aimed to examine the type of rock slope failures and the quality of rock mass as well.The scan-line method was performed in six slopes by using a geological compass to determine rock mass structure on the rock slope,and the condition of joints such as persistence,aperture,roughness,infilling material,weathering and groundwater conditions.Slope kinematic analysis was performed employing a stereographic projection.The rock slope quality and stability were investigated based on RMR(rock mass rating)and SMR(slope mass rating)parameters.The rock slope kinematic analysis revealed that planar failure was likely to occur in Slope 1,3,and 4,the wedge failure in Slope 1 and 6,and toppling failure in Slope 2,5,and 6.The RMR rating is ranging from 57 to 64 and can be categorized as Fair to Good rock.The SMR rating revealed that the failure probability of Slope 3 was 90%,while it was from 40%to 60%for others.Despite the uniform RMR for all slopes,the SMR was significantly different.The detailed quantitative consideration of orientation of joint sets and geometry of the slope contributed to such differences in outcomes.展开更多
To increase the payload,reduce energy consumption,improve work efficiency and therefore must accordingly reduce the total hull weight of the submersible.This paper introduces a design optimization process for the pres...To increase the payload,reduce energy consumption,improve work efficiency and therefore must accordingly reduce the total hull weight of the submersible.This paper introduces a design optimization process for the pressurehull of submarines under uniform external hydrostatic pressure using bothfinite element analysis(FEA)and optimization tools.A comprehensive study about the optimum design of the pressure hull,to minimize the weight and increase the volume,to reach minimum buoyancy factor and maximum operating depth minimizing the buoyancy factor(B.F)is taken as an objective function with constraints of plate and frame yielding,general instability and deflection.The optimization process contains many design variables such as pressure-hull plate thickness,unsupported spacing,dimensions of long and ring beams andfinally the elliptical submersible pressure-hull diameters.The optimization process was conducted using ANSYS parametric design language(APDL)and ISIGHT.The Multi-Island Genetic Algorithm(G.A)is considered to conduct the optimization process.Additionally,parametric analysis is done on the pressure hull to examine the effect of different design variables on the pressure-hull design.As a result,the B.F of the proposed optimal model is reduced by an average of 31.78%compared with Reference Model(RM).Maximum von Mises stress is reduced by 27%as well.These results can be helpful for submarine pressure-hull designers.展开更多
The middle and lower reaches of the Yangtze River are key rice-producing regions in China.Conducting vulnerability assessments on rice production is beneficial for reducing agricultural disaster losses and improving C...The middle and lower reaches of the Yangtze River are key rice-producing regions in China.Conducting vulnerability assessments on rice production is beneficial for reducing agricultural disaster losses and improving China's disaster prevention and control capabilities.This study used a crop growth model to fit hazard-loss rate curves(HLC)representing crop sensitivity to drought,employed an integrated index method to assess the adaptability and coping capacity,and developed a comprehensive vulnerability assessment framework from both physical and social vulnerability dimensions.The results suggest that,high adaptability is concentrated in Jiangsu and northern Zhejiang Provinces,while low adaptability is observed in western Hubei,Hunan,and Anhui Provinces.Approximately 25%of the areas exhibit relatively low coping capacity.Sensitivity levels exceeding 0.4 are primarily found in high-altitude regions,with a general trend of lower sensitivity in the north and higher sensitivity in the south.Comprehensive vulnerability is significantly greater south of the Yangtze River compared to the north,with a positive correlation between altitude and comprehensive vulnerability.Implementing targeted countermeasures based on vulnerability assessments can reduce rice losses in the region and ensure food security.展开更多
Sedimentation is one of the most critical environmental issues facing harbors’authorities that results in significant maintenance and dredging costs.Thus,it is essential to plan and manage the harbors in harmony with...Sedimentation is one of the most critical environmental issues facing harbors’authorities that results in significant maintenance and dredging costs.Thus,it is essential to plan and manage the harbors in harmony with both the environmental and economic aspects to support Integrated Coastal Structures Management(ICSM).Harbors’layout and the permeability of protection structures like breakwaters affect the sediment transport within harbors’basins.Using a multi-step relational research framework,this study aims to design a novel prediction model for estimating the sedimentation quantities in harbors through a comparative approach based on artificial intelligence(AI)algorithms.First,one hundred simulations for different harbor layouts and various breakwater characteristics were numerically performed using a coastal modeling system(CMS)for generating the dataset to train and validate the proposed AIbased models.Second,three AI approaches namely:Support Vector Regression(SVR),Gaussian Process Regression(GPR),and Artificial Neural Networks(ANN)were developed to predict sedimentation quantities.Third,a comparison between the developed models was conducted using quality assessment criteria to evaluate their performance and choose the best one.Fourth,a sensitivity analysis was performed to provide insights into the factors affecting sedimentation.Lastly,a decision support tool was developed to predict harbors’sedimentation quantities.Results showed that the ANN model outperforms other models with mean absolute percentage error(MAPE)equals 4%.Furthermore,sensitivity analysis demonstrated that the main breakwater inclination angle,porosity,and harbor basin width affect significantly sediment transport.This research makes a significant contribution to the management of coastal structures by developing an AI data-driven framework that is beneficial for harbors’authorities.Ultimately,the developed decision-support AI tool could be used to predict harbors’sedimentation quantities in an easy,cheap,accurate,and practical manner compared to physical modeling which is time-consuming and costly.展开更多
While government mandates and programs continue to expand to meet the increasing challenges of disaster management, there is growing recognition that government cannot do it all alone. This has led to a quest to bette...While government mandates and programs continue to expand to meet the increasing challenges of disaster management, there is growing recognition that government cannot do it all alone. This has led to a quest to better understand local capacities, through partnerships with the private sector and volunteer organizations but also in relation to individual citizens. The Federal Emergency Management Agency’s(FEMA) recent Whole Community initiative constitutes a policy shift towards more local engagement and responsibility. However, before devising strategies to better engage and support various actors, the nature of their disaster management resources needs to be more clearly understood. What disaster management resources do communities supply? This case study examined the assets of one community group, the farm community in Sussex County, Delaware. The conceptual framework was based on a community asset approach, which currently recognizes eight types of community capital and is comprised of active, inactive, positive, and negative resources. The study found a striking discrepancy between actually used and perceived community resources. Farm community resources were primarily used for implementation activities during disaster preparedness. The types of resources used fell into three broad categories: equipment/supplies;experience/lessons learned;and access to other community and professional networks. The findings highlighte d the use of four community capitals—human, social, physical, financial—and the existence of active, inactive, negative, and positive resources. Tools currently employed to register community resources, such as the National Incident Management System(NIMS) resource inventory management for rural communities, are designed for professional emergency services but do not recognize the full range of potentially relevant community assets.展开更多
文摘The high mountains of Hindu-Kush Karakoram and Himalaya(HKKH) contain a large volume of snow and ice, which are the primary sources of water for the entire mountainous population of HKKH. Thus, knowledge of these available resources is very important in relation to their sustainable use. A Modified Positive Degree Day Model was used to simulate daily discharge with the contribution of snow and ice melt from the Shigar River Basin, Central Karakoram, Pakistan. The basin covers an area of 6,921 km2 with an elevation range of 2,204 to 8,611 m a.s.l.. Forty percent of the total area is glaciated among which 20% is covered by debris and remaining 80% by clean ice and permanent snow. To simulate daily discharge, the entire basin was divided into 26 altitude belts. Remotely sensed land cover types are derived by classifying Landsat images of 2009. Daily temperature and precipitation from Skardu meteorological station is used to calibrate the glacio-hydrological model as an input variable after correlating data with the Shigar station data(r=0.88). Local temperature lapse rate of 0.0075 °C/m is used. 2 °C critical temperature is used to separate rain and snow from precipitation. The model is calibrated for 1988~1991 and validated for 1992~1997. The model shows a good Nash-Sutcliffe efficiency and volume difference in calibration(0.86% and 0.90%) and validation(0.78% and 6.85%). Contribution of snow and ice melt in discharge is 32.37% in calibration period and 33.01% is validation period. The model is also used to predict future hydrological regime up to 2099 by using CORDEX South Asia RCM considering RCP4.5 and RCP8.5 climate scenarios.Predicted future snow and ice melt contributions in both RCP4.5 and RCP8.5 are 36% and 37%, respectively. Temperature seems to be more sensitive as compared to other input variables, which is why the contribution of snow and ice in discharge varies significantly throughout the whole century.
基金The Project"Development of Korea Operational Oceanographic System(PM57041)"funded by the Ministry of Land,Transport and Maritime Affairs of the Korean Governmentthe Project"Cooperation on the Development of Basic Technologies for the Yellow Sea and East China Sea Operational Oceanographic System(YOOS)"funded by the China-Korea Joint Ocean Research Center(CKJORC)
文摘A standard skill assessment （SA） tool was developed and implemented to evaluate the performance of op- erational forecast models in the Korea operational oceanographic system. The SA tool provided a robust way to assess model skill in the system by comparing predictions and observations, and involved the com- putation of multiple skill metrics including correlation and error skills. User- and system-based acceptance criteria of skill metrics were applied to determine whether predictions were acceptable for the system. To achieve this, the tool produced a time series comparison plot, a skill score table, and an advanced sum- marized diagram to effectively demonstrate the multiple skill scores. Moreover, the SA was conducted to evaluate both atmospheric and hydrodynamic forecast variables. For the atmospheric variables, acceptable error criteria were preferable to acceptable correlation criteria over short timescales, since the mean square error overwhelmed the observation variance. Conversely, for the hydrodynamic variables, acceptable root mean square percentage error （e.g., perms） criteria were preferable to acceptable error （e.g., erms） criteria owing to the spatially variable tidal intensity around the Korean Peninsula. Furthermore, the SA indicated that predetermined acceptance error criteria were appropriate to satisfy a target central frequency （fc） for which errors fell within the specified limits （i.e., the .fc equals 70%）.
基金The Ministry of Oceans and Fisheries of Korea-"The Research and Development on Coastal Hydraulic Investigation of Busan New Port"and"Cooperative Project on Korea-China Bilateral Committee on Ocean Science"the Korea Institute of Ocean Science and Technology(KIOST)Project under contract No.PE99325+1 种基金the China-Korea Joint Ocean Research Center(CKJORC)-"Cooperation on the Development of Basic Technologies for the Yellow Sea and East China Sea Operational Oceanographic System(YOOS)"the Nuclear Safety Project of CKJORC and Major Project of KIOST under contract No.PE99304
文摘Record-breaking high waves occurred during the passage of the typhoon Bolaven（1215）（TYB） in the East China Sea（ECS） and Yellow Sea（YS） although its intensity did not reach the level of a super typhoon.Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys.In order to understand how such high waves with long duration occurred,analyses have been made through measurement and numerical simulations.TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements.And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model.Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area.Thus the accuracy of simulations is considerably enhanced,and the computed results are also in better agreement with measured data than before.It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track.As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days,the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.
基金the HKH Cryosphere Monitoring Project implemented by the International Centre for Integrated Mountain Development (ICIMOD)supported by the Norwegian Ministry of Foreign Affairs
文摘The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons.Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon(2013), winter(2013), and pre-monsoon(2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors(DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of-20.81 °C/m, 4.05 °C/m, and-7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.
基金financially supported by the Thailand International Cooperation Agency(TICA)
文摘Whether groundwater resources can be sustainably utilized is largely determined and characterized by hydrogeological parameters.Estimating the groundwater recharge is one of the essential parameters for managing water resources and protecting water resources from contamination.This study researched the spatial and temporal variation of groundwater recharge in the Thepkasattri sub-district through integrating chloride mass balance(CMB)and water table fluctuation(WTF)methods.The chloride content of representative rainfall and groundwater samples was analyzed.Besides,WTF method was adopted from groundwater level data from 2012 to 2015.According to the CMB method,the mean recharge was estimated to be 1172 mm per year,accounting for 47%of the annual rainfall.Moreover,the estimated recharge from the WTF method took 26%of annual rainfall in 2015.The recharge was underestimated according to the WTF method,because of the uncertainty in specific yield estimates and the number of representative wells in the study area.Moreover,the correlation between rainfall and water table fluctuation data indicated the positive linear relationship between two parameters.The spatial recharge prediction indicated that recharge was higher(1200-1400 mm/yr)in the eastern and western catchment,while that in the central floodplains was between 800 mm/yr and 1100 mm/yr.In addition,low recharge value between 450 mm/yr and 800 mm/yr was observed in the south-west part of Thepkasattri.The spatial variation of recharge partly reflects the influences of land use and land cover of the study area.
基金the Himalayan Cryosphere, Climate and Disaster Research Center (HiCCDRC), Kathmandu University for constant support throughout the researchfunded by The Second Tibetan Plateau Scientific Expedition and Research Program (STEP)(Grant No. 2019QZKK0904)+3 种基金supported by the Comprehensive Investigation and Assessment of Natural Hazards in China-Pakistan Economic Corridor (Grant No. 2018FY100500)Ministry of Science and Technology Basic Resources Survey Project (2018FY100506)International Science andTechnology Cooperation Program of China (No. 2018YFE0100100)the National Natural Science Foundation of China (41925030 and 41661144028)
文摘The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing components of the river discharge.This study examined and compared the hydrological responses in the glacier-dominated Shigar River basin(SRB)under various climatic scenarios using a semi-distributed Modified Positive Degree Day Model(MPDDM)and a distributed Glacio-hydrological Degree-day Model(GDM).Both glacio-hydrological models were calibrated and validated against the observed hydro-meteorological data from 1988–1992 and 1993–1997.Temperature and precipitation data from Shigar and Skardu meteorological stations were used along with field estimated degree-day factor,temperature,and precipitation gradients.The results from both models indicate that the snow and ice melt are vital contributors to sustain river flow in the catchment.However,MPDDM estimated 68%of rain and baseflow contribution to annual river runoff despite low precipitation during the summer monsoon,while GDM estimated 14%rain and baseflow contribution.Likewise,MPDDM calculated 32%,and GDM generated 86%of the annual river runoff from snow and ice melt.MPDDM simulated river discharge with 0.86 and 0.78 NSE for calibration and validation,respectively.Similarly,GDM simulated river discharge with improved accuracy of 0.87 for calibration and 0.84 NSE for the validation period.The snow and ice melt is significant in sustaining river flow in the SRB,and substantial changes in melt characteristics of snow and ice are expected to have severe consequences on seasonal water availability.Based on the sensitivity analysis,both models’outputs are highly sensitive to the variation in temperature.Furthermore,compared to MPDDM,GDM simulated considerable variation in the river discharge in climate scenarios,RCP4.5 and 8.5,mainly due to the higher sensitivity of GDM model outputs to temperature change.The integration of an updated melt module and two reservoir baseflow module in GDM is anticipated to advance the representation of hydrological components,unlike one reservoir baseflow module used separately in MPDDM.The restructured melt and baseflow modules in GDM have fundamentally enriched our perception of glacio-hydrological dynamics in the catchment.
基金the International Centre for Integrated Mountain Development(ICIMOD)and supported by the Norwegian Ministry of Foreign Affairs and Contribution to High Asia Runoff from Ice and Snow(CHARIS)funded by United States Agency for International Development(USAID)through the University of Colorado at Boulder,CO,USA。
文摘Supraglacial debris is widely present on glaciers in alpine environments and its distribution greatly affects glacier melt.The present study aims to determine the effect of debris on glacier ice melt on Ponkar Glacier,Manang District,Nepal.We estimated ice melt under various debris thickness using Energy Balance(EB)model and conductive heat flux methods,which are compared with in-situ observations.Four stakes are installed on the glacier at different debris thickness of 11−40 cm.Meteorological data from March 2016 to May 2018 are obtained from the Automatic Weather Station(AWS)installed on the glacier surface at an elevation of 3,881 m a.s.l.for the energy balance calculation.Debris surface temperature and different debris depths are also measured on the glacier.The calculated ablation rates from the conductive heat flux method are 0.9,1.62 and 0.41 cm/d on pre-monsoon,monsoon and post-monsoon,respectively,with mean debris thermal conductivity 1.04 W/(m∙K).The net radiation shows little variation between the seasons,while turbulent heat flux varies in the season.Sensible heat flux was found to be highest in post-monsoon season due to a larger temperature gradient between surface and air.
基金A 2-Year Research Grant of Pusan National University
文摘Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the region has very high tidal ranges over very gentle tidal flats, which is a very vulnerable region. Although the various remote sensing platforms can be used to map shoreline changes, the spatial and temporal resolutions are not enough to obtain it for a short time. Accordingly, in this study we introduce the newly developed low altitude Helikite remote sensing platform to achieve much better resolutions of shorelines and a bathymetry. The Helikite stands for Helium balloon and Kite, which is a kind of aerial platform that uses the advantages of both a Helium balloon and a kite. Field experiments were conducted in the Jaebu Island, off the coast of the west Korean Peninsula in January 29, 2011. In order to extract shorelines from the consecutive images taken by the low altitude Helikite remote sensing platform, active contours without edges （ACWE） is used. Edges or boundaries exist primarily on places between one type of objective and the other. Since the hydrodynamic pressure has an effect everywhere, the locations of the waterlines can be the isobath lines. We could map several waterlines, which would enable us to complete a local bathymetry map ranges from 35 to 60 cm depth. The error resulting from applying ACWE algorithm to the imagery to determine the waterline is approximately less than 1 m. Therefore, it is very unique way to obtain such high resolutions of bathymetry with high accuracy for the regions of extremely high tidal ranges for a short time.
基金Supported by the National Natural Science Foundation of China(No.50336040)
文摘The resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te has been measured by the superconducting quantum interference device magnetometer in the temperature range from 5 to 200 K under the applied magnetic field of 1, 2, 4 and 6.5 Tesla, respectively, compared with that of no-magnetic field. The results show that the resistivity increases with increase applied magnetic field at higher temperature from 80 to 200 K, but decreases at lower temperature from 5 to 25 K. There exists a transitive range from 25 to 80 K, where the variation of the resistivity shows different tendencies depending on the strength of magnetic field. Maximum difference of resistivity under 6.5 Tesla from that without magnetic field in the temperature range from 30 to 200 K is only about 5 Ω·cm, but it increases up to 3 orders of magnitude at 5 K. The analysis shows that the variation of resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te under the magnetic field is the algebraic sum of the transverse direction magnetoresistance effect and the sp-d exchange interaction effect. TDRME plays major role in the high temperature range. However, with the decrease of temperature, the effect of sp-d EI on the resistivity gradually exceeds that of the transverse direction magnetoresistance effect through the transitive range, and becomes the dominant effect in the temperature range from 5 to 25 K, which leads to the dramatic decrease of resistivity.
文摘A three-dimensional numerical tsunami model is developed to analyze the nonlinear behavior of flow around obstacles with the Marker and Cell （MAC） method based on the Navier-Stokes equations. Tnrough a comparison with experimental data for the cases of dam break and solitary wave propagation, verification of the three-dimensional numerical model is given. Numerical experiment is performed for the analysis of the nonlinear behavior of flow around obstacles and compared with experimental data. The velocity and pressure around obstacles are presented with sufficient accuracy for tstmami propagation passing through an obstacle.
文摘This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling day using the Depth Integration Technique (DIT) on daily basis in the monsoon season, weekly in the pre- and post-monsoon seasons and bi-monthly in the winter season. Suspended sediment concentration (SSC) is calculated from the water samples using filtration followed by oven-drying, and a rating curve is used to calculate daily discharge of the Langtang River. The annual sediment yield is 109,276.75 tons and 37.69, 11.52 and 5.54 tons of sediment is transported per day in the pre-monsoon, post-monsoon and winter seasons, respectively. There is a very high value of 872.86 tons per day in the monsoon season, which contributes the highest sediment load among all of the seasons comprising 83% of the total sediment transport. Diurnal cycle of sediment discharge is clearly seen with higher sediment discharge during the evening than the morning and reaching maximum values of 41.1 kg·s<sup>-1</sup> and 61.5 kg·s<sup>-1</sup>, respectively. A clock-wise hysteresis loop has been obtained for discharge and sediment discharge where sediment flux is higher in the early monsoon than in the late monsoon for a corresponding discharge.
文摘This study was conducted to clarify the food compositions of Corbicula bivalves (C. japonica and leana) in tidal rivers with varied landscapes. In order to grasp their trophic structures, we measured the carbon and nitrogen stable isotope ratios of the collected samples such as the bivalves with varied growth stages and the suspended particulate organic matters (SPOMs) with varied landscapes as their food sources, and then analyzed their relationships with IsoSource mixing model software. The stable isotope ratio measurements clarified that there was a large difference in the ranges of C. japonica and leana in spite of the same sampling locations, and the IsoSource analysis could quantitatively describe their food compositions. According to the results, it could be clarified that the variations in food compositions were dependent not only on the species difference but also on their growth stages. Furthermore, it might suggest that their diet preferences affected the spatial distributions of these Corbicula bivalves in this location.
基金The Research Fund Program of Research Institute for Basic Sciences,Pusan National University,Korea,2012the Project entitled"Cooperative Project on Korea-China Bilateral Committee on Ocean Science"by the Ministry of Oceans and Fisheries,Korea and China-Korea Joint Ocean Research Center
文摘During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment（TSS） can be used as an excellent tracer for Changjiang Diluted Water（CDW）. To analyze the spatial and temporal variations of the CDW distribution, the monthly mean TSS from Moderate Resolution Imaging Spectroradiometer（MODIS） ocean color data are constructed and are converted to salinity using the relationship between salinity observed from AQUARIUS and TSS. The process produces the detailed horizontal distribution of salinity with very high resolution（1 km）. From monthly mean salinity map from 2002 to 2012 in July and August, the expansion patterns of CDW are analyzed. The southerly wind in July and southeasterly wind in August transport the CDW eastward and northeastward, respectively. It is found that the yearly variation of the expansion of CDW toward the southern sea area of Korea is mostly due to the variation of southerly wind and the fluctuations of fresh water discharge into the Changjiang estuary show relatively little impact on the eastward extend of CDW. When 11-year mean（from2002 to 2012） salinity map in August is compared with World Ocean Atlas 2013, it is revealed that wind in August strengthened six times from 1994 and it causes the expansion of CDW extended 150 km further eastward.
基金Funded by the National Natural Science Foundation of China(50336040)
文摘The magnetization of Hg0.89Mn0.11 Te single crystal grown by vertical Bridgman method was studied by using superconducting quantum interference device magnetometer（SQUID Magnetometer）. First, magnetization measurements were done under various magnetic fi eld strengths from-20 kOe to 20 kOe at 5 K, 15 K, and 77 K, respectively. Then, the magnetizations were measured with continuous changes of temperature in the range from 5 K to 300 K under the magnetic field of 0.1 kOe and 10 kOe, respectively. The modifi ed Brillouin function was well fitted with the data of magnetization vs. magnetic field strength. The analysis indicated that there was an antiferromagnetic exchange coupling among Mn^2＋ ions. The results of reciprocal susceptibility vs. temperature fi t Curie-Weiss law very well at the temperatures above 40 K, but deviate from the law from 5 Kto 40 K, which shows that the antiferromagnetic exchange coupling among Mn^2＋ ions increases in the lower temperature range below 40 K. The experimental result was explained by extending higher-order terms in the calculation of susceptibility and fitted by a power law function. The measurements reveal that Hg0.89Mn0.11 Te possesses paramagnetic properties at temperatures from 5 K to 300 K.
基金The part of the project "Development of Korea Operational Oceanographic System(KOOS),Phase 2",funded by the Ministry of Oceans and Fisheries,Koreathe part of the project entitled "Cooperative Project on Korea-China Bilateral Committee on Ocean Science",funded by the Ministry of Oceans and Fisheries,Korea and China-Korea Joint Research Ocean Research Center
文摘Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide（a.k.a algal bloom） model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%–50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly required.As opposed to the bioassay data, it is necessary because the bioassay data have limitations in terms of the in-situ coastal conditions.
文摘Rock slope kinematic analysis and rock mass classifications has been conducted at the 17^(th) km to 26^(th) km of USAID(United States Agency for International Development)highway in Indonesia.This research aimed to examine the type of rock slope failures and the quality of rock mass as well.The scan-line method was performed in six slopes by using a geological compass to determine rock mass structure on the rock slope,and the condition of joints such as persistence,aperture,roughness,infilling material,weathering and groundwater conditions.Slope kinematic analysis was performed employing a stereographic projection.The rock slope quality and stability were investigated based on RMR(rock mass rating)and SMR(slope mass rating)parameters.The rock slope kinematic analysis revealed that planar failure was likely to occur in Slope 1,3,and 4,the wedge failure in Slope 1 and 6,and toppling failure in Slope 2,5,and 6.The RMR rating is ranging from 57 to 64 and can be categorized as Fair to Good rock.The SMR rating revealed that the failure probability of Slope 3 was 90%,while it was from 40%to 60%for others.Despite the uniform RMR for all slopes,the SMR was significantly different.The detailed quantitative consideration of orientation of joint sets and geometry of the slope contributed to such differences in outcomes.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(No.NRF-2021R1A2B5B02002599)。
文摘To increase the payload,reduce energy consumption,improve work efficiency and therefore must accordingly reduce the total hull weight of the submersible.This paper introduces a design optimization process for the pressurehull of submarines under uniform external hydrostatic pressure using bothfinite element analysis(FEA)and optimization tools.A comprehensive study about the optimum design of the pressure hull,to minimize the weight and increase the volume,to reach minimum buoyancy factor and maximum operating depth minimizing the buoyancy factor(B.F)is taken as an objective function with constraints of plate and frame yielding,general instability and deflection.The optimization process contains many design variables such as pressure-hull plate thickness,unsupported spacing,dimensions of long and ring beams andfinally the elliptical submersible pressure-hull diameters.The optimization process was conducted using ANSYS parametric design language(APDL)and ISIGHT.The Multi-Island Genetic Algorithm(G.A)is considered to conduct the optimization process.Additionally,parametric analysis is done on the pressure hull to examine the effect of different design variables on the pressure-hull design.As a result,the B.F of the proposed optimal model is reduced by an average of 31.78%compared with Reference Model(RM).Maximum von Mises stress is reduced by 27%as well.These results can be helpful for submarine pressure-hull designers.
基金supported by the National Natural Science Foundation of China(Grant No.42201087)the National Key Research and Development Program of China(Grant No.2024YFE0214000)the Natural Science Foundation of Zhejiang Provincial(Grant No.LQ21D010009)。
文摘The middle and lower reaches of the Yangtze River are key rice-producing regions in China.Conducting vulnerability assessments on rice production is beneficial for reducing agricultural disaster losses and improving China's disaster prevention and control capabilities.This study used a crop growth model to fit hazard-loss rate curves(HLC)representing crop sensitivity to drought,employed an integrated index method to assess the adaptability and coping capacity,and developed a comprehensive vulnerability assessment framework from both physical and social vulnerability dimensions.The results suggest that,high adaptability is concentrated in Jiangsu and northern Zhejiang Provinces,while low adaptability is observed in western Hubei,Hunan,and Anhui Provinces.Approximately 25%of the areas exhibit relatively low coping capacity.Sensitivity levels exceeding 0.4 are primarily found in high-altitude regions,with a general trend of lower sensitivity in the north and higher sensitivity in the south.Comprehensive vulnerability is significantly greater south of the Yangtze River compared to the north,with a positive correlation between altitude and comprehensive vulnerability.Implementing targeted countermeasures based on vulnerability assessments can reduce rice losses in the region and ensure food security.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(NRF-2021R1A2B5B02002599).
文摘Sedimentation is one of the most critical environmental issues facing harbors’authorities that results in significant maintenance and dredging costs.Thus,it is essential to plan and manage the harbors in harmony with both the environmental and economic aspects to support Integrated Coastal Structures Management(ICSM).Harbors’layout and the permeability of protection structures like breakwaters affect the sediment transport within harbors’basins.Using a multi-step relational research framework,this study aims to design a novel prediction model for estimating the sedimentation quantities in harbors through a comparative approach based on artificial intelligence(AI)algorithms.First,one hundred simulations for different harbor layouts and various breakwater characteristics were numerically performed using a coastal modeling system(CMS)for generating the dataset to train and validate the proposed AIbased models.Second,three AI approaches namely:Support Vector Regression(SVR),Gaussian Process Regression(GPR),and Artificial Neural Networks(ANN)were developed to predict sedimentation quantities.Third,a comparison between the developed models was conducted using quality assessment criteria to evaluate their performance and choose the best one.Fourth,a sensitivity analysis was performed to provide insights into the factors affecting sedimentation.Lastly,a decision support tool was developed to predict harbors’sedimentation quantities.Results showed that the ANN model outperforms other models with mean absolute percentage error(MAPE)equals 4%.Furthermore,sensitivity analysis demonstrated that the main breakwater inclination angle,porosity,and harbor basin width affect significantly sediment transport.This research makes a significant contribution to the management of coastal structures by developing an AI data-driven framework that is beneficial for harbors’authorities.Ultimately,the developed decision-support AI tool could be used to predict harbors’sedimentation quantities in an easy,cheap,accurate,and practical manner compared to physical modeling which is time-consuming and costly.
文摘While government mandates and programs continue to expand to meet the increasing challenges of disaster management, there is growing recognition that government cannot do it all alone. This has led to a quest to better understand local capacities, through partnerships with the private sector and volunteer organizations but also in relation to individual citizens. The Federal Emergency Management Agency’s(FEMA) recent Whole Community initiative constitutes a policy shift towards more local engagement and responsibility. However, before devising strategies to better engage and support various actors, the nature of their disaster management resources needs to be more clearly understood. What disaster management resources do communities supply? This case study examined the assets of one community group, the farm community in Sussex County, Delaware. The conceptual framework was based on a community asset approach, which currently recognizes eight types of community capital and is comprised of active, inactive, positive, and negative resources. The study found a striking discrepancy between actually used and perceived community resources. Farm community resources were primarily used for implementation activities during disaster preparedness. The types of resources used fell into three broad categories: equipment/supplies;experience/lessons learned;and access to other community and professional networks. The findings highlighte d the use of four community capitals—human, social, physical, financial—and the existence of active, inactive, negative, and positive resources. Tools currently employed to register community resources, such as the National Incident Management System(NIMS) resource inventory management for rural communities, are designed for professional emergency services but do not recognize the full range of potentially relevant community assets.
