Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and...Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and shape.The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots,but crown dynamic models has seldom been constructed.Therefore,this study aimed to develop height to crown base(HCB)and crown length(CL)dynamic models using the branch mortality technique for a Korean larch plantation.The nonlinear mixed-eff ects model with random eff ects,variance functions and correlation structures,was used to build HCB and CL dynamic models.The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China.The results showed that HCB progressively increases as tree age,tree height growth(HT growth)and diameter at breast height growth(DBH growth).The CL was increased with tree age in 20 years ago,and subsequently stabilized.HT growth,DBH growth stand basal area(BAS)and crown competition factor(CCF)signifi cantly infl uenced HCB and CL.The HCB was positively correlated with BAS,HT growth and DBH growth,but negatively correlated with CCF.The CL was positively correlated with BAS and CCF,but negatively correlated with DBH growth.Model fi tting and validation confi rmed that the mixed-eff ects model considering the stand and tree level random eff ects was accurate and reliable for predicting the HCB and CL dynamics.However,the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation,and the fi tting precision of the models was reduced.Therefore,from the point of view of application,we should take care to avoid setting up over-complex models.The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.展开更多
Topography can have signifi cant eff ects on seismic ground response during an earthquake because topographic irregularities cause considerable diff erences between the seismic waves emitted by the source and the wave...Topography can have signifi cant eff ects on seismic ground response during an earthquake because topographic irregularities cause considerable diff erences between the seismic waves emitted by the source and the waves reaching the ground surface. When a seismic motion happens in a topographically irregular area, seismic waves are trapped and refl ected between the topographic features. Therefore, the interaction between topographies can amplify seismic ground response. In order to reveal how interaction between topographies infl uences seismic response, several numerical fi nite element studies have been performed by using the ABAQUS program. The results show that topographic features a greater distance between the seismic source and the site would cause greater seismic motion amplifi cation and is perceptible for the hills far away from the source and the ridges. Also, site acceleration response is impacted by surrounding topography further than site velocity and displacement response.展开更多
Mesoscale coupling between perturbations of mesoscale sea surface temperature (SST) and lowlevel winds has been extensively studied using available high-resolution satellite observations. However, the climatological i...Mesoscale coupling between perturbations of mesoscale sea surface temperature (SST) and lowlevel winds has been extensively studied using available high-resolution satellite observations. However, the climatological impacts of mesoscale SST perturbations (SST meso ) on the free atmosphere have not been fully understood. In this study, the rectified eff ect of SSTmeso on local climatological precipitation in the Kuroshio- Oyashio Extension (KOE) region is investigated using the Weather Research and Forecasting (WRF) Model;two runs are performed, one forced by low-resolution SST fields (almost no mesoscale signals) and another by additional high-resolution SSTmeso fields extracted from satellite observations. Climatological precipitation response to SST meso is characterized mainly by enhanced precipitation on the warmer flank of three oceanic SST fronts in this region. The results show that the positive correlation between the 10-m wind speed perturbations and SSTmeso is well captured by the WRF model with a reasonable spatial pattern but relatively weak strength. The addition of SSTmeso improves the climatological precipitation simulated by WRF with a better representation of fine-scale structures compared with satellite observations. A closer examination on the underlying mechanism suggests that while the pressure adjustment mechanism can explain the climatological precipitation enhancement along the fronts and the relatively high contribution of the convective precipitation, other factors such as synoptic events should also be taken into consideration to account for the seasonality of the precipitation response.展开更多
The HAMSOM(Hamburg Shelf Ocean Model),a high-resolution regional ice-ocean coupled model,was applied to investigate the seasonal evolution of Bohai Sea ice for winter 2015/2016.HAMSOM was initialized with monthly clim...The HAMSOM(Hamburg Shelf Ocean Model),a high-resolution regional ice-ocean coupled model,was applied to investigate the seasonal evolution of Bohai Sea ice for winter 2015/2016.HAMSOM was initialized with monthly climatological temperature and salinity data from WOA13 and driven by hourly meteorological data obtained from the NCEP above the sea surface and tides at the open boundary.The ice model used here is a modifi ed Hibler-type dynamic-thermodynamic sea ice model based upon viscous-plastic rheology.The ice extent,concentration,area,thickness,length of ice season as well as the distance between the top of Liaodong Bay(North China)and the outer ice edge line were simulated and compared with the observed data.Three types of modeling experiments were carried out to investigate the eff ects of wind,tide,and both wind and tide on Bohai Sea ice.The results show that wind,as both a dynamic and a thermodynamic factor,has a signifi cant impact on the ice thickness,ice area,and ice-freezing and ice breakup dates as well as the ice velocity,while tides are a dynamic factor that infl uences only the ice velocity.During the severe ice period,the wind speed intensity increased by 25%,the average ice thickness thickened by approximately 4.0 cm in Liaodong Bay,approximately 2.1 cm in Bohai Bay and approximately 2.5 cm in Laizhou Bay,and the total ice coverage area and total ice actual area increased by about 2×104 km 2 and 1.4×104 km 2,respectively.While the tidal amplitude intensity increased by 25%,the average ice velocity increased by approximately 0.1 m/s.展开更多
To highlight the importance of small earthquakes in seismic hazard, a study of the 11 May 2016, Mw 4.9, Tesistan, Mexico earthquake is presented. Due to the close proximity of the event to the city, accelerations were...To highlight the importance of small earthquakes in seismic hazard, a study of the 11 May 2016, Mw 4.9, Tesistan, Mexico earthquake is presented. Due to the close proximity of the event to the city, accelerations were considerably higher than those caused by historical severe earthquakes (6.0 < Mw < 8.2). This paper addresses two objectives related to the Tesistan event: the fi rst is to estimate the focal mechanism solution in order to place the event in the context of the tectonic environment of this area. The second is focused on a vulnerability evaluation of buildings that suff ered resonance. Several building′s typologies with variations in construction system and height are assessed in terms of resonance with the structural and soil periods. The results show that around the Zapopan station, strong damage is expected in intermediate to high-rise buildings (12-30 m) with moment resistant frame systems and in reinforced concrete shear walls. Masonry structures around this station may not present resonance. In contrast, in the surroundings of the Guadalajara station, all intermediate height buildings from 9 to 21 m may present resonance.展开更多
Inventory data were available from 96 plots of even-aged,monoculture,tall-open forests of Eucalyptus pilularis Smith,aged 2-63 years,growing in sub-tropical regions along the east coast of Australia.A model was develo...Inventory data were available from 96 plots of even-aged,monoculture,tall-open forests of Eucalyptus pilularis Smith,aged 2-63 years,growing in sub-tropical regions along the east coast of Australia.A model was developed relating the maximum possible stem basal area growth rate of individual trees to their stem basal area.For any tree size,this maximum increased as site productivity increased.However,the size at which this maximum occurred decreased as productivity increased.Much research has shown that,at any stand age,trees of a particular stem basal area are taller on more productive sites than on less productive ones.Taller trees incur greater respiratory costs to ensure maintenance of the photo synthetic capacity of their canopies;this reduces their growth rates.It was concluded that trees with larger basal areas will have the maximum possible growth rate on a less productive site,whilst trees with smaller basal areas will have the maximum possible on a more productive site.The model developed may constitute the first stage of a complete individual tree growth model system to predict wood yields from these forests.展开更多
The integration of the Czech Republic into the process of European space university education formation makes many demands on the higher education system--from creating new legislation and educational conception to ch...The integration of the Czech Republic into the process of European space university education formation makes many demands on the higher education system--from creating new legislation and educational conception to changes in the study programme structure. With regard to the study programme structure, permeability and modular construction of the programme and the actual European Credit Transfer and Accumulation System （ECTS） implementation are some of requirements coming to the fore. The aim of this work is to present an analysis of bachelor study programme Applied Mathematics Structure at the University of Ostrava within the context of the above mentioned requirements.展开更多
基金supported by the National Key Research and Development Program of China(2017YFD0600401)the Fundamental Research Funds for the Central Universities(2572019CP08)
文摘Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and shape.The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots,but crown dynamic models has seldom been constructed.Therefore,this study aimed to develop height to crown base(HCB)and crown length(CL)dynamic models using the branch mortality technique for a Korean larch plantation.The nonlinear mixed-eff ects model with random eff ects,variance functions and correlation structures,was used to build HCB and CL dynamic models.The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China.The results showed that HCB progressively increases as tree age,tree height growth(HT growth)and diameter at breast height growth(DBH growth).The CL was increased with tree age in 20 years ago,and subsequently stabilized.HT growth,DBH growth stand basal area(BAS)and crown competition factor(CCF)signifi cantly infl uenced HCB and CL.The HCB was positively correlated with BAS,HT growth and DBH growth,but negatively correlated with CCF.The CL was positively correlated with BAS and CCF,but negatively correlated with DBH growth.Model fi tting and validation confi rmed that the mixed-eff ects model considering the stand and tree level random eff ects was accurate and reliable for predicting the HCB and CL dynamics.However,the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation,and the fi tting precision of the models was reduced.Therefore,from the point of view of application,we should take care to avoid setting up over-complex models.The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.
文摘Topography can have signifi cant eff ects on seismic ground response during an earthquake because topographic irregularities cause considerable diff erences between the seismic waves emitted by the source and the waves reaching the ground surface. When a seismic motion happens in a topographically irregular area, seismic waves are trapped and refl ected between the topographic features. Therefore, the interaction between topographies can amplify seismic ground response. In order to reveal how interaction between topographies infl uences seismic response, several numerical fi nite element studies have been performed by using the ABAQUS program. The results show that topographic features a greater distance between the seismic source and the site would cause greater seismic motion amplifi cation and is perceptible for the hills far away from the source and the ridges. Also, site acceleration response is impacted by surrounding topography further than site velocity and displacement response.
基金Supported by the National Key Research and Development Program of China(Nos.2017YFC1404102,2017YFC1404100)the National Natural Science Foundation of China(Nos.41490644,41490640)+2 种基金the Chinese Academy of Sciences Strategic Priority Project,the Western Pacific Ocean System(No.XDA11010105)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406402)the Taishan Scholarship and the Recruitment Program of Global Experts
文摘Mesoscale coupling between perturbations of mesoscale sea surface temperature (SST) and lowlevel winds has been extensively studied using available high-resolution satellite observations. However, the climatological impacts of mesoscale SST perturbations (SST meso ) on the free atmosphere have not been fully understood. In this study, the rectified eff ect of SSTmeso on local climatological precipitation in the Kuroshio- Oyashio Extension (KOE) region is investigated using the Weather Research and Forecasting (WRF) Model;two runs are performed, one forced by low-resolution SST fields (almost no mesoscale signals) and another by additional high-resolution SSTmeso fields extracted from satellite observations. Climatological precipitation response to SST meso is characterized mainly by enhanced precipitation on the warmer flank of three oceanic SST fronts in this region. The results show that the positive correlation between the 10-m wind speed perturbations and SSTmeso is well captured by the WRF model with a reasonable spatial pattern but relatively weak strength. The addition of SSTmeso improves the climatological precipitation simulated by WRF with a better representation of fine-scale structures compared with satellite observations. A closer examination on the underlying mechanism suggests that while the pressure adjustment mechanism can explain the climatological precipitation enhancement along the fronts and the relatively high contribution of the convective precipitation, other factors such as synoptic events should also be taken into consideration to account for the seasonality of the precipitation response.
基金Supported by the Project“Oceanic Instruments Standardization Sea Trials(OISST)”,the National Key Research and Development Plan(No.2016YFC1401300),and the Taishan Scholars Program。
文摘The HAMSOM(Hamburg Shelf Ocean Model),a high-resolution regional ice-ocean coupled model,was applied to investigate the seasonal evolution of Bohai Sea ice for winter 2015/2016.HAMSOM was initialized with monthly climatological temperature and salinity data from WOA13 and driven by hourly meteorological data obtained from the NCEP above the sea surface and tides at the open boundary.The ice model used here is a modifi ed Hibler-type dynamic-thermodynamic sea ice model based upon viscous-plastic rheology.The ice extent,concentration,area,thickness,length of ice season as well as the distance between the top of Liaodong Bay(North China)and the outer ice edge line were simulated and compared with the observed data.Three types of modeling experiments were carried out to investigate the eff ects of wind,tide,and both wind and tide on Bohai Sea ice.The results show that wind,as both a dynamic and a thermodynamic factor,has a signifi cant impact on the ice thickness,ice area,and ice-freezing and ice breakup dates as well as the ice velocity,while tides are a dynamic factor that infl uences only the ice velocity.During the severe ice period,the wind speed intensity increased by 25%,the average ice thickness thickened by approximately 4.0 cm in Liaodong Bay,approximately 2.1 cm in Bohai Bay and approximately 2.5 cm in Laizhou Bay,and the total ice coverage area and total ice actual area increased by about 2×104 km 2 and 1.4×104 km 2,respectively.While the tidal amplitude intensity increased by 25%,the average ice velocity increased by approximately 0.1 m/s.
文摘To highlight the importance of small earthquakes in seismic hazard, a study of the 11 May 2016, Mw 4.9, Tesistan, Mexico earthquake is presented. Due to the close proximity of the event to the city, accelerations were considerably higher than those caused by historical severe earthquakes (6.0 < Mw < 8.2). This paper addresses two objectives related to the Tesistan event: the fi rst is to estimate the focal mechanism solution in order to place the event in the context of the tectonic environment of this area. The second is focused on a vulnerability evaluation of buildings that suff ered resonance. Several building′s typologies with variations in construction system and height are assessed in terms of resonance with the structural and soil periods. The results show that around the Zapopan station, strong damage is expected in intermediate to high-rise buildings (12-30 m) with moment resistant frame systems and in reinforced concrete shear walls. Masonry structures around this station may not present resonance. In contrast, in the surroundings of the Guadalajara station, all intermediate height buildings from 9 to 21 m may present resonance.
文摘Inventory data were available from 96 plots of even-aged,monoculture,tall-open forests of Eucalyptus pilularis Smith,aged 2-63 years,growing in sub-tropical regions along the east coast of Australia.A model was developed relating the maximum possible stem basal area growth rate of individual trees to their stem basal area.For any tree size,this maximum increased as site productivity increased.However,the size at which this maximum occurred decreased as productivity increased.Much research has shown that,at any stand age,trees of a particular stem basal area are taller on more productive sites than on less productive ones.Taller trees incur greater respiratory costs to ensure maintenance of the photo synthetic capacity of their canopies;this reduces their growth rates.It was concluded that trees with larger basal areas will have the maximum possible growth rate on a less productive site,whilst trees with smaller basal areas will have the maximum possible on a more productive site.The model developed may constitute the first stage of a complete individual tree growth model system to predict wood yields from these forests.
文摘The integration of the Czech Republic into the process of European space university education formation makes many demands on the higher education system--from creating new legislation and educational conception to changes in the study programme structure. With regard to the study programme structure, permeability and modular construction of the programme and the actual European Credit Transfer and Accumulation System （ECTS） implementation are some of requirements coming to the fore. The aim of this work is to present an analysis of bachelor study programme Applied Mathematics Structure at the University of Ostrava within the context of the above mentioned requirements.
