Recent studies have shown that cache-conscious indexes such as the CSB+-tree outperform conventional main memory indexes such as the T-tree. The key idea of these cache-conscious indexes is to eliminate most of child pointers from a node to increase the fanout of the tree. When the node size is chosen in the order of the cache block size, this pointer elimination effectively reduces the tree height, and thus improves the cache behavior of the index. However, the pointer elimination cannot be directly applied to multidimensional index structures such as the R-tree, where the size of a key, typically, an MBR (minimum bounding rectangle), is much larger than that of a pointer. Simple elimination of fourbyte pointers does not help much to pack more entries in a node. This paper proposes a cache-conscious version of the R-tree called the CR-tree. To pack more entries in a node, the CR-tree compresses MBR keys, which occupy almost 80% of index data in the two-dimensional case. It first represents the coordinates of an MBR key relatively to the lower left corner of its parent MBR to eliminate the leading 0's from the relative coordinate representation. Then, it quantizes the relative coordinates with a fixed number of bits to further cut off the trailing less significant bits. Consequently, the CR-tree becomes significantly wider and smaller than the ordinary R-tree. Our experimental and analytical study shows that the two-dimensional CR-tree performs search up to 2.5 times faster than the ordinary R-tree while maintaining similar update performance and consuming about 60% less memory space.

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<p><strong>Abstract.</strong> Railways were a key mode of transporting goods and people for industrial and urban development in the late modern age. Their special part in economic growth comes with their role in the development of cultural heritage along their pathways. However, because of competing urban construction, many railway heritages are in danger, such as the Yunnan-Vietnam Railway (YVR) in China, an important international narrow-gauge railway built in 1901, acknowledged as a railway heritage in 2018. As a typical linear heritage, the railway integrates both the natural and cultural landscapes, related to the large spatial extent and complex composition of single heritage elements. Geographic Information Systems (GIS) offer a great support in the investigation, assessment, and management of railway heritage. In this research, the huge cultural heritage related to the YVR was studied using a combined geo-historical and GIS approach. This paper aims to 1) give a brief review of the current status of the application of GIS on linear railway heritages studies, including heritage resources surveys, spatial analysis, thematic mapping and public service, 2) introduce the case study of the Yunnan-Vietnam Railway, and 3) present a geodatabase design for the Yunnan-Vietnam Railway heritage management.</p>

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Historical villages bear historical, cultural, architectural, aesthetic, and landscape values, but they are facing a series of dangers and problems during the process of urbanization. Digital survey for traditional villages plays a crucial role in the preservation, planning, and development of this kind of heritage. The introduction of the terrestrial laser scanning technique is essential for heritage surveying, mapping, and modeling due to its advantages of noncontact measurement, accurate sensing of complex objects, and efficient operation. In recent years, TLS and related processing software (“SCENE”) have been widely presented as effective techniques for dealing with the management and protection of historical buildings in Fenghuang village. Thus, this paper highlights the process of using laser scanning to obtain architectural data, process point clouds, and compare the characteristics of historical buildings in Fenghuang village. The cloud-to-cloud registration technique is applied to build point clouds. As a result of model construction, some architectural patterns are summarized in this village, such as the spatial sequence of ancestral halls, the dominant position of memorial halls, and the character of building decorations and roof slopes. Furthermore, a BIM model is also explained to fulfill the statistical function for architectural components. In the future, more research can be fulfilled based on the built point cloud model, which will be beneficial for the development of the whole village.

Constructed wetland parks in urban areas can offer potential for an integration of water conservation and purification. Compared with other treatments, filtering out pollutants by wetland plants is one of the methods used widely for its fast processing time and limited costs. And species allocation plays an important role in the purification process. However, some problems are still waiting for further discussions, such as the purification efficiency in winter due to plant growth rate, etc. Against this background, this paper introduced the Tianhe Wetland Park in China as the site for a comparative experiment, to propose a methodology testing the purification effect under different plant communities. Through site investigation and lab experiment with water monitoring, the process of water purification by wetland was simulated in the park. After a period of observation and measurement, seven water indexes (pH value, dissolved oxygen, total phosphorus, total nitrogen, ammonia nitrogen, chemical oxygen demand, and turbidity) were selected for the evaluation of water quality to compare the different absorption efficiency by different communities. As a result, the research showed that a configuration of plant community using arboreal, emergent, and submerged plants can carry out a good purification effect during the winter, including Callistemon viminalis, Bischofia javanica, Canna indica, Juncus effusus, Vallisneria natans, and Hydrilla verticillata var. rosburghii. The removal rate of DO, TU, COD, TP and TN by the designed community can reach to 43%, 65%, 45%, 51% and 62% in sampling sites. Finally, based on the research results, further suggestions for the development of wetlands were proposed to improve the park management in the study area.

The visual aesthetics of villages are remarkably affected by the exterior quality of traditional residences, influencing the impression and assessment of local culture. A proper scientific assessment of exterior quality can protect traditional cultures and improve the development of villages. This research was conducted in a village consisting of 115 residences (Mengjinglai village, which is on the border between China and Myanmar). The backpropagation (BP) neural network model with genetic algorithm (GA) was applied to evaluate the quality of the dwellings. All the evaluation values of the dwellings were defined by scores. Meanwhile, the score of each residence was affected by three main factors: architectural spatial elements, architectural construction elements, and historical and cultural elements. The results show that the village’s dwellings are well preserved and clearly express the traditional Dai style. Moreover, the GA–BP approach is more suitable than the traditional BP method for the assessment of the exterior quality. The quantitative machine learning model would be useful for other aspects of the assessment of similar villages in the future.

Historical photos have significance for historical and social studies. Especially, the introduction of Geographic Information System (GIS) and digitalized historical photos have brought more opportunities and possibilities for interdisciplinary studies and the convenience for normal citizens to participate in the landscape observation. To this aim, this paper first reviews the research related to historical photos and Open GIS, and points out the meaning of historical photos for the Yunnan–Vietnam Railway (YVR). Based on the collected data of original historical photos from archives and the fieldwork data that recorded the landscape along the railway from 2018 to 2019, a WebGIS of Yunnan–Vietnam Railway is designed and implemented with open GIS tools. All the data are processed in the QGIS as vector and raster layers and loaded in PostgreSQL as relational tables. Then, heatmaps are created indicating the density of historical activities of the railway company, the other historical photographers, and current touristic activities. Connected with the PostgreSQL database, the data are uploaded to GeoServer for more GIS functionalities. Finally, the whole system lives in a webpage, implemented in HTML and JavaScript with Leaflet, and the improved functionalities of the Yunnan–Vietnam Railway WebGIS include distance measuring, search engine, and historical information browsing. In the future, further research can be done focusing on the landscape changes along the railway and public participation during the landscape observation.