Landscape Pattern Evolution Processes of Alpine Wetlands and Their Driving Factors in the Zoige Plateau of China

Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau.The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dynamic changes in landscape modification and conversion and their dynamic rates of alpine wetlands over the past four decades.The results showed that the landscape conversion between wetlands and non-wetlands mainly occurred during the period from 1966 to 1986.The marsh wetland area converted from lake and river wetlands was larger because of swamping compared to other wetland landscapes.Meanwhile,the larger area of marsh wetlands was also converted to lake wetlands more than other types of wetlands.The modification processes mainly occurred among natural wetland landscapes in the first three periods.Obvious conversions were observed between wetland and nonwetland landscapes(i.e.,forestland,grassland,and other landscapes) in the Zoige Plateau.These natural wetland landscapes such as river,lake and marsh wetlands showed a net loss over the past four decades,whereas artificial wetland landscapes(i.e.,paddy field and reservoir and pond wetlands) showed a net decrease.The annual dynamic rate of the whole wetland landscape was 0.72%,in which the annual dynamic rate of river wetlands was the highest,followed by lake wetlands,while marsh wetlands had the lowest dynamic rate.The integrated landscape dynamic rate showed a decreasing trend in the first three periods.The changes in wetland landscape patterns were comprehensively controlled by natural factors and human activities,especially human activities play an important role in changing wetland landscape patterns.

The spatial relationship between salt marsh vegetation patterns,soil elevation and tidal channels using remote sensing at Chongming Dongtan Nature Reserve, China

The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt marsh.Since the exotic species Spartina alterniflora（S. alterniflora） was introduced in 1995, a rapid expansion has occurred at Chongming Dongtan Nature Reserve（CDNR） in the Changjiang（Yangtze） River Estuary, China.Several important vegetation-environment factors including soil elevation, tidal channels density（TCD）,vegetation classification and fractional vegetation cover（FVC） were extracted by remote sensing method combined with field measurement. To ignore the details in interaction between biological and physical process,the relationship between them was discussed at a large scale of the whole saltmarsh. The results showed that Scirpus mariqueter（S. mariqueter） can endure the greatest elevation variance with 0.33 m throughout the marsh in CDNR. But it is dominant in the area less than 2.5 m with the occurrence frequency reaching 98%. S. alterniflora has usually been found on the most elevated soils higher than 3.5 m but has a narrow spatial distribution. The rapid decrease of S. mariqueter can be explained by stronger competitive capacity of S. alterniflora on the high tidal flat. FVC increases with elevation which shows significant correlation with elevation（r=0.30, p〈0.001）. But the frequency distribution of FVC indicates that vegetation is not well developed on both elevated banks near tidal channels from the whole scale mainly due to tidal channel lateral swing and human activities. The significant negative correlation（r=–0.20, p〈0.001） was found between FVC and TCD, which shows vegetation is restricted to grow in higher TCD area corresponding to lower elevation mainly occupied by S. mariqueter communities. The maximum occurrence frequency of this species reaches to 97% at the salt marsh with TCD more than 8 m/m2.

Crack patterns corresponding to the residual strength plateau of ceramics subjected to thermal shock

The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm×50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of ther- mal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.

Changes in family structure in China:the impact of residence patterns and demographic factors

Based on census data from China,this paper uses SOCSIM microscopic simulation method to decompose the key factors of family transition into demographic and residence pattern factors.The former are further broken down into demographic inertia,fertility,mortality and marriage rate.The results indicate that the current demographic changes are relatively small and,thus,the small fluctuations caused by demographic changes contribute much less than residence pattern to the family transition.Among the demographic factors,demographic inertia and fertility have a greater effect on family transition and the impacts caused by fertility and marriage rate are consistent with the direction of the overall influence of demographic factors:increasing the proportion of single-person households,one-generation households,and two-generation households,and decreasing the proportion of three-generation or more households.In contrast,the effect of mortality rate was opposite to that of fertility rate,which increased the proportion of populations living in single-person,one-generation,and two-generation households,but the decreased the proportion of the population living in three-generation or more households.

Criterion of aerodynamic performance of large-scale offshore horizontal axis wind turbines

With the background of offshore wind energy projects, this paper studies aerodynamic performance and geometric characteristics of large capacity wind turbine rotors （1 to 10 MW）, and the main characteristic parameters such as the rated wind speed, blade tip speed, and rotor solidity. We show that the essential criterion of a high- performance wind turbine is a highest possible annual usable energy pattern factor and a smallest possible dimension, capturing the maximum wind energy and producing the maximum annual power. The influence of the above-mentioned three parameters on the pattern factor and rotor geometry of wind turbine operated in China＇s offshore meteoro- logical environment is investigated. The variation patterns of aerodynamic and geometric parameters are obtained, analyzed, and compared with each other. The present method for aerodynamic analysis and its results can form a basis for evaluating aerodynamic performance of large-scale offshore wind turbine rotors.

Sensitivity Analysis of Pollutants and Pattern Factor in a Gas Turbine Model Combustor due to Changes in Stabilizing Jets Characteristics

In the present paper,a sensitivity analysis of pollutants and pattern factor in a model combustor due to changes in the geometrical characteristics of stabilizing jets has been carried out.The exhaust pollutants including NO_(x),CO and soot have been chosen due to their harmful effect on the environment.The pattern factor has been also considered owing to its impact on turbine blades.The geometrical characteristics comprise diameter,angle and position of stabilizing jets.Eulerian-Lagrangian approach has been employed to model liquid fuel injection and distribution,breakup and evaporation of droplets.For the analysis of reactive-spray flow characteristics,RANS approach,realizable k-εturbulence model,discrete ordinates radiative heat transfer model and steady flamelet combustion model together with the chemical reaction mechanism of diesel fuel(C_(10)H_(22))have been applied.NO_(x) modeling has been performed via post-processing.Sensitivity analysis is such that by making variations in the problem inputs(diameter,angle and position of jets)in an organized manner,the effects on the outputs(NO_(x),CO,soot and pattern factor)are predicted.The number and order of simulations are predicted by design of experiments and full factorial model.Results have been analyzed using analysis of variance.It has been observed that if interactions among the characteristics of jets are considered,it is possible to analyze the exhaust pollutants more accurately.In fact,by using the interactions,it is likely to find a point where all output parameters are improved.Results show that by considering interactions of stabilizing jet characteristics,the maximum values of NO_(x),CO,soot and pattern factor change from 13.927 ppm,11.198%mole fraction,2.877 ppm and 0.043 to 26.233 ppm,14.693%mole fraction,142.357 ppm and 0.060,respectively.Furthermore,the minimum values change from 5.819 ppm,7.568%mole fraction,0.013 ppm and 0.029 to 6.098 ppm,5.987%mole fraction,0.002 ppm and 0.027,respectively.