Pendahuluan Pertemuan 9

1. PendahuluanPertemuan 9 Matakuliah : H0062/Teori Sistem Tahun : 2006

2. Contoh Modeling Watershed Modeling(http://water.usgs.gov/osw/techniques/watershed.html)

3. Overview The interdisciplinary nature and increasing complexity of environmental and water-resource problems require the use of modeling approaches that can incorporate knowledge from a broad range of scientific disciplines. Selection of a model to address these problems is difficult given the large number of available models and the potentially wide range of applications, data constraints, and spatial and temporal scales of application. Coupled with these issues are the problems of study area characterization and parameterization after a model is selected. Guidelines for parameter estimation are sparse, and the user commonly has to make decisions based on an incomplete understanding of the relation between parameter values and physical measures of watershed characteristics. The U.S. Geological Survey is currently addressing these issues by developing a watershed modeling framework that promotes models that are problem- and-scale specific and that provides a capability to evaluate alternative modeling and parameter estimation approaches.

4. Conceptually, the framework is an integrated system of computer software designed to provide the modeling tools needed to support a broad range of model applications and model user skills. The framework supports the (1) application and analysis of existing models, (2) modification and enhancement of existing models for problem-specific applications, and (3) research, devleopment, testing, and application of new models. The framework uses a module library that contains modules for simulating a variety of physical processes. A model is created by selectively coupling appropriate modules from the library to create a suitable model for a desired application. When existing modules do not provide appropriate process algorithms, new modules can be developed.

5. A wide range of pre-processing and post-processing capabilities and model optimization and sensitivity analysis tools are also major components of a watershed modeling framework. Pre-processing capabilities include a range of data management and analysis tools and geographic information system (GIS) tools to provide watershed delineation, characterization, and parameterization capabilities. Post- processing tools include graphical and statistical analysis tools for use in analyzing and interpreting results.

6. Continued advances in the physical and biological sciences, GIS technology, computer technology, and data resources will increase the need for a set of dynamic tools capable of providing a simple interface between research and operational applications. A watershed modeling framework provides a flexible mechanism for integrating scientific and technological capabilities with resource planning and management requirements.

7. Modeling Parameter Heterogeneity in Cross Country Growth Regression Models (http://ideas.repec.org/p/ucy/cypeua/0212.html)

8. Given the failure of the conventional linear Solow growth model to establish reliable results in the analysis cross-country growth performance, this paper proposes a new framework using the concept of hierarchy of time-scales. By hierarchy of time scales, I mean that slower moving variables such as culture, play a major role in determining medium moving variables such as institutions, and which in turn play a major role in determining faster moving variables such as the conventional determinants of economics growth. This approach provides a systematic way of thinking about the heterogeneity in the cross-country growth performance. In the context of the Solow growth model the hierarchical approach suggests a local generalization of the Solow growth model in the form of a semiparametric varying parameter model along the lines of Hastie and Tibshirani (1992). Using the varying coefficient model, this paper studies two examples. In the first example the parameters of the model vary according to initial human capital while in the second they vary according to a measure of ethnic diversity. The results suggest that there exists substantial parameter heterogeneity in the cross-country growth process.