倾斜摄影测量中影响模型精度的因素分析

目前,倾斜摄影测量作为一种新技术,经过不断的探索、应用和发展,已开始在测绘行业中大显身手,并取得了不小的成绩。通过三维模型进行的矢量数据采集,其矢量精度完全依赖于三维模型精度。论文以实践经验为基础,定性地分析了在航空摄影、像控测量、模型生产三阶段中,影响模型精度的因素,希望对三维模型的生产起到一定的指导作用。     

供应链管理环境下我国中小型第三方物流企业运营解决方案

通过对目前我国中小型第三方物流企业市场现状的分析，从供应链一体化的角度，阐明了提高企业营运竞争力的重要性，并试探性地提出了有关我国中小型第三方物流企业如何在营运层面上提高竞争力的建议与解决方案：     

Less Government—More Wealth? On the Macroeconomics of a Smaller Public Sector in Europe

In this paper, we analyze the reactions of European economies to a fiscal policy strategy aiming at diminishing the public sector. Within the framework of the MSG3 model, a macroeconomic model of the world economy, we perform several simulation experiments to explore the effects of reducing government expenditures permanently in different phases of the business cycle. For this purpose, we combine the fiscal contraction with negative and positive, Euro Area-wide and global, supply and demand shocks. It turns out that adverse Keynesian effects on output and employment tend to be mostly weak and short-lived, whereas long-run effects on output and employment are favorable. Due to these long-run effects, the fiscal contraction policy raises welfare as measured by an asymmetric quadratic objective function. The size of these welfare effects depends on the initial situation in a non-trivial manner.     

How many voters are needed for paradoxes?

Summary. This paper presents a general procedure for finding profiles with the minimum number of voters required for many important paradoxes. Borda's and Condorcet's classic examples are revisited as well as generalizations. Using Saari's procedure line, we obtain an upper bound for the minimum number of voters needed for a profile for which the Condorcet winner is not strictly top ranked for all weighted positional procedures. Also we give a simple upper bound on the minimum number of voters needed for a set of prescribed voting outcomes. In contrast to situations wherein small numbers of voters are needed, we consider paradoxes requiring arbitrarily large numbers of voters as well as large numbers of alternatives. Finally we indicate connections with statistical rank based tests. Received: April 18, 2001; revised version: May 25, 2001     

Institutions,quality competition and public service provision: The case of public education

This paper contributes to the literature on integovernmental competition in two ways. First, the institutional setting within which public services are delivered is analyzed with respect to the impact on the quality of services provided. Previous studies have measured competition only in terms of governmental structure, ignoring the issue of service quality and the potential for differentiating local governmental jurisdictions along quality dimensions. Second, the outcome of competition is defined in terms of service quality. Previous studies generally have measured the outcome of competition by examining the fiscal effects of fragmentation and accountability through service costs or tax revenue impacts. School districts were used to empirically test quality competition. Student academic performance was modeled as a function of control variables and the degree of competition from neighboring school districts. Academic performance in public schools was positively associated with the performance of neighboring districts, although the effect was small. These findings, however, suggest that strategies to strengthen interjurisdictional competition may be useful in enhancing public service quality.     

Wage inequality, technology, and trade

The recent widening of wage inequality has been attributed by some to skill-biased-technical-change and by others to trade liberalization. This paper examines the two explanations within a unified model and also presents a new modeling of skill-biased-technical-change, where skilled workers replace unskilled ones. As a result technology adoption is endogenous and does not occur in all countries. Hence, wages for both types of workers, trade patterns and also factor productivities in all countries are endogenously determined. The model sheds light on the relationship between technology and trade, on the reasons for global productivity differences and on the causes for the recent rise in wage inequality.     

Education, Work and Wages in the UK

Abstract. This paper is concerned with the relationship between education, wages and working behaviour. The work is partly motivated by the sharp distinction in the literature between the returns to education and the effect of wages on labour supply. Education is the investment that cumulates in the form of human capital while labour supply is the utilization rate of that stock. Yet, variation in education is usually the basis for identifying labour supply models – education is assumed to determine wages but not affect labour supply. Moreover, it is commonly assumed that the private rate of return to education can be found from the schooling coefficient in a log-wage equation. Yet, the costs of education are largely independent of its subsequent utilization but the benefits will be higher the greater the utilization rate. Thus the returns will depend on how intensively that capital is utilized and we would expect that those who intend to work least to also invest least in human capital. Indeed, the net (of tax liabilities and welfare entitlements) return to education will be a complex function of labour supply and budget constraint considerations.
Here we attempt to model the relationship between wages, work, education and the tax/welfare system allowing for the endogeneity of education as well for the correlations between the unobservable components of wages and working behaviour. We use the estimates to simulate the effect of a new UK policy designed to increase education for children from low-income households.     

Experiencing change and the evolution of adaptive skills: Implications for economic growth

We distinguish learning in a static environment from that in a dynamic environment to show the existence of an important interaction between the development of new technologies and human capital accumulation. Because technological progress creates a more dynamic environment, it complements education in the production of human capital by enhancing adaptive skills. Higher levels of adaptability and human capital in turn determine the profitability of new inventions and the incentive to invest in new R&D. Differences in the history of technological progress produce different levels of adaptability and our results suggest why countries that have comparable levels of education and per capita incomes may differ significantly in their growth performance.     

Education, segregation and marital sorting: theory and an application to the UK

This paper presents a model of the intergenerational transmission of education and marital sorting. Parents matter both because of their household income and because their human capital determines the distribution of a child's disutility from making an effort to become skilled. We show that an increase in segregation has potentially ambiguous effects on the proportion of individuals that become skilled in the steady state, and hence on marital sorting, the personal and household income distribution, and welfare. We calibrate the steady state of our model to UK statistics. We find that an increase in the correlation of spouses in their years of education will bring about a small increase in the proportion of skilled individuals when the relative supply of skilled individuals is variable at the family level and a decrease when this supply is fixed. Ex-ante utility (of an unborn individual) increases in the first case and decreases in the second. The welfare effect of increased sorting is negative for unskilled individuals and positive for skilled individuals. Increased segregation always leads to an increase in welfare inequality between skilled and unskilled individuals.