THE POSITIVE SOLUTION OF CLASSICAL GELFAND MODEL WITH COEFFICIENT THAT CHANGE SIGN

The existence and iteration of positive solution for classical Gelfand models are considered, where the coefficient of nonlinear term is allowed to change sign in [0, 1]. By using the monotone iterative technique, an existence theorem of positive solution is obtained, corresponding iterative process and convergence rate are given. This iterative process starts off with zero function, hence the process is simple, feasible and effective.

Analysis and calculating for preheat temperature and average convection heat change coefficient in the continue annealing furnace

The aim of the thesis is to utilize essential theory of heat transfer,to use correlative expressions to calculate average convection heat change coefficient and heating temperature of strip in Jet Preheat Furnace (JPF),make the calculating results accordant with production data,and make the calculation to be used the process of production.The method is to collect:entry temperature and speed of strip,temperature and speed of N_2 - H_2,to analyse heat transfer according to length and thickness of strip,jet hole and mutual position of jet piping in JPF,to analyse heat transfer and built the physical model.In mathematic model, Martin correlative expressions are tried to calculate using the data from production,and are modified in part properly.At the same time,heat boundary condition is analysed with theory of impact jet and production data.The conclusion is obtained that boundary condition is rarely average numerical value of temperature of strip and N_2 - H_2 with impact jet condition,instead of a relation of function of temperature of strip, temperature and speed of N_2- H_2,array of jet holes,diameter of hole,distance between hole and strip,and acquired a calculating expression.In calculation of examples,the thesis collected and calculated 15 kinds of strips.The thickness of strips are 2=0.51~1.41 mm,material DQ - IF、DDQ,EDDQ,SEDDQ and 340DDQ.Main assess numerical value is temperature value after strip is heated with certain speed and within section of time.Maximum error in 9 groups of numerical value in the thesis is 3.36%comparing with production data.The correlative expressions can be used in production to adjust temperature of strip through changing speed and temperature of N_2 - H_2 and speed of strip.The correlative expressions are compiled computer process.The process can be applied in on line control of production by rapid calculating speed.

Incorporating shape constraints in generalized additive modelling of the height-diameter relationship for Norway spruce

Background： Measurements of tree heights and diameters are essential in forest assessment and modelling. Tree heights are used for estimating timber volume, site index and other important variables related to forest growth and yield, succession and carbon budget models. However, the diameter at breast height （dbh） can be more accurately obtained and at lower cost, than total tree height. Hence, generalized height-diameter （h-d） models that predict tree height from dbh, age and other covariates are needed. For a more flexible but biologically plausible estimation of covariate effects we use shape constrained generalized additive models as an extension of existing h-d model approaches. We use causal site parameters such as index of aridity to enhance the generality and causality of the models and to enable predictions under projected changeable climatic conditions. Methods： We develop unconstrained generalized additive models （GAM） and shape constrained generalized additive models （SCAM） for investigating the possible effects of tree-specific parameters such as tree age, relative diameter at breast height, and site-specific parameters such as index of aridity and sum of daily mean temperature during vegetation period, on the h-d relationship of forests in Lower Saxony, Germany. Results： Some of the derived effects, e.g. effects of age, index of aridity and sum of daily mean temperature have significantly non-linear pattern. The need for using SCAM results from the fact that some of the model effects show partially implausible patterns especially at the boundaries of data ranges. The derived model predicts monotonically increasing levels of tree height with increasing age and temperature sum and decreasing aridity and social rank of a tree within a stand, The definition of constraints leads only to marginal or minor decline in the model statistics like AIC An observed structured spatial trend in tree height is modelled via 2-dimensional surface fitting. Conclusions： We demonstrate that the SCAM approach allows optimal regression modelling flexibility similar to the standard GAM but with the additional possibility of defining specific constraints for the model effects. The longitudinal character of the model allows for tree height imputation for the current status of forests but also for future tree height prediction.

Multi-decadal variations in glacier flow velocity and the influencing factors of Urumqi Glacier No.1 in Tianshan Mountains, Northwest China

Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis. Results show that the glacier flow velocity decreased from 5.5 m/a in 1980/1981 to 3.3 m/a in 2010/2011. The annual variation in the direction of glacier flow velocity in the western branch and eastern branch was less than 1°–3°, and the change of glacier flow velocity in the western branch was more dramatic than that in the eastern branch. Glacier flow velocity was influenced by glacier morphology（including glacier area, glacier length, and ice thickness）, glacier mass balance and local climate conditions（air temperature and precipitation）, the glacier morphology being the leading factor. The long-term flow velocity data set of Urumqi Glacier No. 1 contributes to a better understanding of glacier dynamics within the context of climatic warming.

An Analysis of the Increase of CO2 Emissions in China： Based on an SDA technique

This paper creates an extended import-competitive economy-energy-environmental input/output model and employs a structural decomposition analysis （SDA） approach based on double-layer nested structural formulae to break down China＇s carbon dioxide emissions growth between 1992 and 2007from three perspectives： the overall economy, by-industry and by industrial sectors. Analysis results indicate that the energy intensity effect remains the biggest factor behind carbon emissions reduction. This paper also .found that between 2002 and 2007, China＇s carbon emissions growth obviously accelerated compared to the previous period, which indicates a ＂high carbon＂ tendency in the new round of industrialization. Therefore, in addition to developing a circular economy and clean production, accelerating the phasing out of backward capacities, and developing new energies, China should further encompass the positive role of energy intensity.

Study on Trends of Change in Direct Input Coefficients of China

The objective of this paper is to study the trends of change in direct input coefficients of China. We reconstructed a time series of input\|output tables of China with 18 sectors for 1981, 1987, 1990, 1992 and 1995 at constant prices and current prices, and the tables for developed region, middle developed region and underdevelopd region. On the basis of these tables we found seven important trends on change in China′s direct input coefficients.

ITERATION OF POSITIVE SOLUTION FOR A SECOND-ORDER ORDINARY DIFFERENTIAL EQUATION WITH CHANGE OF SIGN

An iterative process of positive solution for BVP w'+h(t)f(w)=0, w(0)=w(1)= 0 is established, where h(t) is allowed to changes sign on [0,1]. The process starts from a simple function.

Impact of Climate Change on Maize Potential Productivity and the Potential Productivity Gap in Southwest China

The impact of climate change on maize potential productivity and the potential productivity gap in Southwest China（SWC） are investigated in this paper.We analyze the impact of climate change on the photosynthetic,light-temperature,and climatic potential productivity of maize and their gaps in SWC,by using a crop growth dynamics statistical method.During the maize growing season from 1961 to 2010,minimum temperature increased by 0.20℃ per decade（p 〈 0.01） across SWC.The largest increases in average and minimum temperatures were observed mostly in areas of Yunnan Province.Growing season average sunshine hours decreased by 0.2 h day^（-1） per decade（p 〈 0.01） and total precipitation showed an insignificant decreasing trend across SWC.Photosynthetic potential productivity decreased by 298 kg ha^（-1）per decade（p 〈 0.05）.Both light-temperature and climatic potential productivity decreased（p 〈 0.05） in the northeast of SWC,whereas they increased（p 〈 0.05） in the southwest of SWC.The gap between lighttemperature and climatic potential productivity varied from 12 to 2729 kg ha^（-1）,with the high value areas centered in northern and southwestern SWC.Climatic productivity of these areas reached only 10%-24%of the light-temperature potential productivity,suggesting that there is great potential to increase the maize potential yield by improving water management in these areas.In particular,the gap has become larger in the most recent 10 years.Sensitivity analysis shows that the climatic potential productivity of maize is most sensitive to changes in temperature in SWC.The findings of this study are helpful for quantification of irrigation water requirements so as to achieve maximum yield potentials in SWC.