There are indications suggesting that the density economy of the railway transport service really exists, the decline of the average transportation cost is caused because of the high frequency using fixed assets.

City comes from goods exchange and reflects the objective demand of improved efficiency of exchange. The efficiency of exchange from density economy is a criteria to measure the reasonable size of a city, and the development of a city promotes the merchandise circulation from simple stage to advanced.

There have been a lot of ambiguities, or even mistakes, in both defining and using the concepts of economies of network, economies of scale, economies of scope, economies of traffic density, economies of size and so on in previous studies, so many confusions exit in this field.

The paper presents that economies of transport network are composed by economies of traffic density and network size, which are transformed from economies of scale and economies of scope, and which take on many other transformations in practice.

The land-use change in Longitudinal Range-Gorge Region largely occurred in that area where lower contour, slope between 15~0 ～25~0 , population density and economy density obviously change.

However the genetic gain of wood density was 6.27% and the volume was not decreased at all selected through index D with heritability 0.702.It was applicable that the aggregate evaluation and directional selection of multi-characters could be done with selection index.

For exploring competitive advantage of transport network expansion,based on three ways acquiring scale economics of transport network: economics of density,size and scope,authors proposed that economics of scope was main contribution of transport network expanding endpoints.

In recent years many works have been published concerning the problem of optimal plant-ing density of crops and much attention has been paid to the density at which maximumyield is.attained.Since this density is not always the most profitable one,what is neededin practice is the yield-density curve and not only a single point on it.In this paper at-tempts have been made to establish the quantitative expression of this curve,together witha brief discussion of several formulae proposed by other workers.The first...

In recent years many works have been published concerning the problem of optimal plant-ing density of crops and much attention has been paid to the density at which maximumyield is.attained.Since this density is not always the most profitable one,what is neededin practice is the yield-density curve and not only a single point on it.In this paper at-tempts have been made to establish the quantitative expression of this curve,together witha brief discussion of several formulae proposed by other workers.The first method of approach is to establish the relation of mean head weight (w) to thenumber of culms per unit area (y).It may conform to one of the following equations,as thecase may be:u=a'-b'y (1-2)andw=α+b(1/y)+c(1/y)~2 (1-3)where a',b',a,b,and care constants.From these equations we obtain the correspondingequations for yield-density relation,and those for optimal density,Y_(opt).Thus,from (1-2)we haveW=a'y-b'y~2 (1-4)andu_(opt)=α'/(2b') (1-5)and from (1-3) we haveW=ay+b+cy~(-1) (1-6)andY_(?)=(c/a)~(1/2) (1-7)These equations may be expressed in terms of density x by substituting the following equa-tion into them:y=α+βx (1-1)The second method of approach is to consider the effect of density on total dry weight(W_b) and on a conversion factor K_E,which is the ratio W/W_b,W being the total grain yield.W_b was found to be a logarithmic function of density,and may be expressed asW_b=W_(bo)+Klnx (2-1)where W_(bo)and K are constants.From the fact that head weight w is a linear function of tiller weightW=b((W_(b-α)) (2-3)where a and b are constants,usually both positive,the conversion factor K_E was found tobe a function of mean culm weight,W_b K_E=b-(ab)/W (2-4)The value of K_E tends to decrease as density increases and thereby W_b decreases.The relation between yield and density has been thus obtained:W=YW=bW_b+aby (2-5)Then,substituting (1-1) and (2-1),we haveW=b(W_(bo)+Klnx)-ab(α+βx) (2-7)and the optimal density is (2-8)x_(opt).=1/(βακ)All these equations are valid only in certain density range,though the range is wide enoughfor practical purposes.

Taiwan is one of the festoon islands bordering the western Pacific which is the high seismicity re-gion in China as well as in the whole globol.As to the earthquake,the important thing is at prevention,as is just the same to other natural hazards. The developing productive forces and the disaster reduction and prevention is two aspects of eco-nomic construction,they are supplement each other and not a single one can be omitted.So that,inthis paper,the problem of mitigating earthquake hazards is discussed with...

Taiwan is one of the festoon islands bordering the western Pacific which is the high seismicity re-gion in China as well as in the whole globol.As to the earthquake,the important thing is at prevention,as is just the same to other natural hazards. The developing productive forces and the disaster reduction and prevention is two aspects of eco-nomic construction,they are supplement each other and not a single one can be omitted.So that,inthis paper,the problem of mitigating earthquake hazards is discussed with consideration of the currentpopulation density and economic development of Taiwan.The author wish that the proper authoritiesof Taiwan may pay attention to this problem.

In this paper, the time and space characteristics of large earthquakes and serious hazard earthquake (dead more than 10) in the world during 1990 - 1995 are studied. We emphasize on the correlation of hazard earthquake , seismicity, humanistic geography , economic geograph original time and other factors . We conclude that the injured or dead is not only depending on the seismic activity , but also local population density , local economic developing level and original time.