云南机场产业发展存在问题及对策

从1999年到2003年，云南机场的旅客吞吐量年平均增长率达22．8％，呈现快速发展的良好势头，另外，云南机场产业具有优越的区位优势，潜力很大，但在机场产业发展中面临许多问题，需要不断思考。运用相关的因子对比分析，较为系统地阐述了影响云南省机场产业发展的优势和劣势相关的条件因素，在此基础上，明确指出目前云南省机场产业发展中存在的问题和不足，继而提出解决问题的具体措施和建议，以便更好地促进云南机场产业的可持续发展。     

用日定时观测能见度划分沙尘暴强度存在的问题

选取宁夏24个气象站1955—2003年沙尘暴观测资料及其沙尘暴出现当日的能见度定时观测资料,分析研究了宁夏单站沙尘暴天气强度划分时存在的问题,结果表明:用沙尘暴当日定时观测最小能见度资料划分沙尘暴天气强度存在很大的片面性,有53%的沙尘暴天气无法划分其强弱、69%的沙尘暴天气发生在非定时观测时间段内,通过典型个例,对比分析了日定时观测最小能见度对沙尘暴天气强度划分的影响和存在的偏差,为历史沙尘暴强度的划分提供参考。     

Problem-Based Learning for Promoting Student Learning in High School Geography

ABSTRACT

This study determines the impact of problem-based learning on a preuniversity geography class. Learning activities include problem analysis, information collection, an examination of concepts, oral presentations, and group summaries in relation to current and perennial geographical issues of local and/or global concern. Assessment for learning and assessment of learning were done by the teacher, classmates, and students themselves. Results showed that students could analyze problem statements and present their understanding systematically but varied considerably in organization, argument, and quality of thinking. To seek improvements, teachers should become more active facilitators while encouraging students to learn as problem solvers. Teacher training and school-based support are needed for creating a collaborative inquiry-oriented atmosphere in the classroom.     

中国西部河谷型城市发展及其环境问题

分析了1949年以来中国西部河谷型城市的数目变化与空间分布、规模与职能变化。在此基础上，以西部部分河谷型城市为例，讨论了影响该类城市的环境污染和热岛效应等城市环境问题，并研究了环境问题的成因，认为工业化过程与城市化过程、地形条件、工业的空间布局、建设用地结构不合理和城市建设的间接效应等是造成目前西部河谷型城市环境问题突出的主要原因。     

A probabilistic approach to the inversion of data from a seismic array and its application to volcanic signals

Array techniques are particularly well‐suited for detecting and quantifying the complex seismic wavefields associated with volcanic activity such as volcanic tremor and long‐period events. The methods based on the analysis of the signal in the frequency domain, or spectral methods, have the main advantages of both resolving closely spaced sources and reducing the necessary computer time, but may severely fail in the analysis of monochromatic, non‐stationary signals. Conversely, the time‐domain methods, based on the maximization of a multichannel coherence estimate, can be applied even for short‐duration pulses. However, for both the time and the frequency domain approaches, an exhaustive definition of the errors associated with the slowness vector estimate is not yet available. Such a definition become crucial once the slowness vector estimates are used to infer source location and extent. In this work we develop a method based on a probabilistic formalism, which allows for a complete definition of the uncertainties associated with the estimate of frequency–slowness power spectra from measurement of the zero‐lag cross‐correlation. The method is based on the estimate of the theoretical frequency–slowness power spectrum, which is expressed as the convolution of the true signal slowness with the array response pattern. Using a Bayesian formalism, the a posteriori probability density function for signal slowness is expressed as the difference, in the least‐squares sense, between the model spectrum and that derived from application of the zero‐lag cross‐correlation technique. The method is tested using synthetic waveforms resembling the quasi‐monochromatic signals often associated with the volcanic activity. Examples of application to data from Stromboli volcano, Italy, allow for the estimate of source location and extent of the explosive activity.     

中国开展战略环境评价中存在的问题及其对策

简要介绍了战略环境评价在中国的研究进展,分析了战略环境评价在中国开展的过程中在立法、行政及方法、指标体系和公众参与等方面存在的缺陷和不足,并提出了克服困难的对策。     

Time-domain electromagnetic migration in the solution of inverse problems

Time-domain electromagnetic (TDEM) migration is based on downward extrapolation of the observed field in reverse time. In fact, the migrated EM field is the solution of the boundary-value problem for the adjoint Maxwell's equations. The important question is how this imaging technique can be related to the solution of the geoelectrical inverse problem. In this paper we introduce a new formulation of the inverse problem, based on the minimization of the residual-field energy flow through the surface or profile of observations. We demonstrate that TDEM migration can be interpreted as the first step in the solution of this specially formulated TDEM inverse problem. However, in many practical situations this first step produces a very efficient approximation to the geoelectrical model, which makes electromagnetic migration so attractive for practical applications. We demonstrate the effectiveness of this approach in inverting synthetic and practical TDEM data.     

中国开发区的发展回顾与战略思考

经过20多年的发展，开发区已经成长到了一个新的历史阶段。对开发区的建立发展和相关研究进行简单回顾后，总结出中国开发区的发展历程：摸索阶段、繁荣阶段和调整阶段；探讨了现阶段其面临的四大战略问题：认为开发区应定位为具有相对综合功能的新型城区；外向型和内向型的产业相结合；摆脱“孤岛”状态，逐步与周边地区融合、一体化的发展；同时应该慎重地对待开发区的体制变化，从而适应现阶段国内外的经济环境和实现自身的持续发展。     

A transformational approach to geophysical inverse problems

A set of coordinate transformations is used to linearize a general geophysical inverse problem. Statistical and analytic techniques are employed to estimate the parameters of such linearization transformations. In the transformed space, techniques from linear inverse theory may be utilized. Consequently, important concepts, such as model parameter covariance, model parameter resolution and averaging kernels, may be carried over to non-linear inverse problems. I apply the approach to a set of seismic cross-borehole traveltimes gathered at the Conoco Borehole Test Facility. the seismic survey was conducted within the Fort Riley formation, a limestone with thin interbedded shales. Between the boreholes, the velocity structure of the Fort Riley formation consists of a high-velocity region overlying a section of lower velocity. It is found that model parameter resolution is poorest and spatial averaging lengths are greatest in the underlying low-velocity region.