Yi Long

On the impact of granularity of time to linear topological relations between geographical events and their formalization

The time scale is an important element of spatial-temporal data model thatdetermines the level of detail to characterize and describe the geographic information. In spatial-temporal databases, time granularity has a decisive impact on the topological spatial-temporal relationship of geographical objects. In this paper, at first a formal definition of basic elements of time has been put forward. Then based on set theory, the number axes can be divided into three parts according to the number of time of geographical event. Based on the intersection of the sets of two-time elements a formal description of the 9 intersection model of the linear time topological relationships between geographical events has been established. On this basis, the impacts of time granularity to topological relationships of linear time between geographic events also has been discussed with a case study.

Extended fractal analysis method and its application for linear rivers

Extended fractal analysis method can analyze the fractal character (i.e. self-similarity) objectively, especially the difference and change of the shape and the structure in different observation scale intervals. As one of the common fractal objects, river on the map can be surveyed its length and quantified the complexity of its shape and structure as well as its partial details with Extended Fractal Dimension Analysis method (abbreviated as EFDA). Compared to the traditional method, EFDA has unparalleled advantages. Considering the extended fractal character with scaling variance, and based on its simulating function adopting the Inverse Logistic Model, the paper gained the extended fractal function for quantifying the length of the river depending on the different observing scales. Furthermore, based on the mathematical derivation of its simulating function and fractal analysis, the paper obtained the relevant parameter for establishing Meta Fractal Dimension (abbreviated as MFD) Model to quantify the local complexity of the river on the map. Several experiments based on the Chinas seven major rivers done indicate that this method is easy to operate and has a relatively high calculation precision and a logical result of spatial analysis.

Research on a Chinese word segmentation method based on spatial information query of GIS

Spatial information query is one of the most fundamental applications in GIS. Spatial information query based on Chinese means making a query in forms of Chinese language. Word segmentation is the first step in the process of query understanding. With the help of related searching method to extract the characteristic words from the input sentence, we can segment it into several parts for further analyzing, and then map them to a subset of spatial information database and feed back the result to the user. This thesis tries to improve the study of Chinese spatial information query and proposes a word segmentation method based on a set of characteristic words. The method rearranges the query sentence according to the given patterns and abandons the irrelevant words. Moreover, when meeting the wrong object names or unknown ones, it will amend or insert them into the dynamic library automatically. Such word segmentation method not only takes away the identification of irrelevant words but improves its efficiency of spatial information query and makes for the following mapping to the spatial database.

The construction of CNL rules in mobile GIS

Natural language has been considered as one of the most habitual and effective ways of human-computer interaction (HCI). This paper proposes the constrained principles in the perspective of mobile GIS nature language, and it also restricts understanding of natural language in the domain of the specific application in mobile GIS. For implementing the interaction between mobile GIS and users with nature language, we should establish the grammar rules and the understanding method of these rules in the view of system control and spatial information inquiry. We use speech technology and mobile GIS to carry human-computer interaction out in order to achieve a friendlier, more intelligent, and easier operated way for the visit of user and the expression of information. It can promote mobile GIS to a state which is more intelligent and socialized and also improve its degree of practicality.

An automatic method to determine the size of sliding window for metafractal dimension curve and its application

The Meta Fractal Dimension (abbreviated as MFD) Model is a method which extends the fractal research of map objects. During the establishment of MFD, the size of sliding window determines the neighborhood range which restricts the segment from the map object and the degree of adjacent overlapped, thus it is one of the most important parameters for MFD. In present research, however, it is chosen artificially, that causes random and unsatisfied operating efficiency. Considering the extended fractal character with scaling variance, and based on its simulating function adopting the Inverse Logistic Model, the paper proposed a method to determine the size of sliding window automatically for constructing MFD of map curve, viz. MFD curve. Several experiments done indicate that this method is easy to operate and has a relatively high calculation precision and a logical result of spatial analysis.

The research of object selection method based on rough set in map generalization

Object selection is an important technical problem in the process of map generalization. Considering creative-thinking characteristic of map generalization process, the paper bring the Rough Set theory from spatial data mine field to map generalization field, put forward a new thought for map generalization based on classification idea of Rough Set. The method of Rough Set which has the benefit on enormous data with the imperfection and non-precision character has become a new tool to make research on spatial data mining. The paper analyzes the imperfection characters of geo-spatial data processing based on Rough Set and the selection problem in the processing of map generalization with classification thought; presents the thought that map generalization is a kind of classification for map objects. The method mentioned in this paper use different spatial and attribute information as different point of view to observe the map objects. The result of the classification is ordered by the weightiness of all kinds of factors. In the end, a river objects selection test validates the rough set map generalization method mentioned in this paper.

The application of speech technology in mobile GIS

How to apply natural language and speech technology is one of the important contents that increase the intelligent degree of mobile GIS and improve its serving system. From system structure and application demand of mobile GIS, this paper basically explained the application objective and key techniques of speech and natural language in mobile GIS, discussed the multi application modes of speech and natural language that includes the centralized mode and the distributed mode, the perfect natural language mode, the human-computer conversation mode and the mixed mode among them, the speaker-dependent mode and the speaker- independent mode. Finally some primary application methods, about how to adopt these speech application modes in mobile GIS, were synoptically analyzed.