69 research outputs found
Life Cycle Characteristics of Warm-Season Severe Thunderstorms in Central United States from 2010 to 2014
Weather monitoring systems, such as Doppler radars, collect a high volume of measurements with fine spatial and temporal resolutions that provide opportunities to study many convective weather events. This study examines the spatial and temporal characteristics of severe thunderstorm life cycles in central United States mainly covering Kansas, Oklahoma, and northern Texas during the warm seasons from 2010 to 2014. Thunderstorms are identified using radar reflectivity and cloud-to-ground lightning data and are tracked using a directed graph model that can represent the whole life cycle of a thunderstorm. Thunderstorms were stored in a GIS database with a number of additional thunderstorm attributes. Spatial and temporal characteristics of the thunderstorms were analyzed, including the yearly total number of thunderstorms, their monthly distribution, durations, initiation time, termination time, movement speed and direction, and the spatial distributions of thunderstorm tracks, initiations, and terminations. Results revealed that thunderstorms were most frequent across the eastern part of the study area, especially at the borders between Kansas, Missouri, Oklahoma, and Arkansas. Finally, thunderstorm occurrence is linked to land cover, including a comparison of thunderstorms between urban and surrounding rural areas. Results demonstrated that thunderstorms would favor forests and urban areas. This study demonstrates that advanced GIS representations and analyses for spatiotemporal events provide effective research tools to meteorological studies
How do Internet applications affect process innovation in Chinese manufacturing companies?
This study distinguishes between two dimensions of firm process
innovation, namely, quantity and quality, and uses data from the
World Bank’s China Manufacturing Firm Survey to analyse the differential
impact of Internet applications on the quantity and quality
of process innovation and their mechanisms of action. Internet
applications have a significant facilitating effect on the quantity
and quality of process innovation. However, from the perspective
of the average marginal effect, the facilitating effect of Internet
applications on the quantity of process innovation is greater than
that on the quality of process innovation. Further analysing firm
size, industry, ownership, and regional heterogeneity shows that in
terms of the quantity of process innovation, Internet applications
have a greater impact on small- and medium-sized firms, labourintensive
firms, non-state-owned firms, and eastern firms. As for the
quality of process innovation, Internet applications have a stronger
promoting effect on large firms, technology-intensive firms, and
state-owned firms. The mechanism test reveals that open innovation
and informatisation capability play a mediating role in the
influence of a firm’s Internet applications on process innovation.
This study provides micro-empirical evidence for firms’ Internet
applications to promote process innovation and policy insights into
China’s manufacturing transformation and upgrading
Influence of pretreatment on properties of bamboo portland cement particle board
Bamboo contains water-soluble saccharides and carboxylic acid which have an anticoagulation effect on Portland cement, and the anticoagulation ingredients can directly influence the hydration reaction extent. Hydration product varieties and hydration product-bamboo shaving binding interfaces of the Portland cement, and finally the mechanical properties of bamboo cement particle boards. In this paper, bamboo shavings are pretreated by carbonizing treatment, hydro-thermal treatment and alkali treatment; highperformance liquid chromatography is adopted to analyze the influences of three different pretreatment methods on contents of water-soluble saccharides and carboxylic acid in the bamboo shavings; a Fourier infrared spectrometer and an X-ray diffractometer are respectively utilized to analyze the characteristic peak changes and crystallization property changes of chemical ingredients of the bamboo shavings before and after the three types of pretreatment.This paper discusses effects of three types of pretreatment methods in eliminating water-soluble saccharides and carboxylic acid in the bamboo shavings. Bamboo Portland cement particle boards was prepared using bamboo shavings, which are pretreated in three ways, and influences and mechanisms of different pretreatment methods on properties of the bamboo Portland cement particle boards were studied. Research indicates that the mechanical properties of the Portland cement particle board prepared from bamboo shavings pretreated with 3 % NaOH solution are superior to requirements of qualified products and superior products specified in the Standard GBT24312 (GB 2009)
Morphing of Building Footprints Using a Turning Angle Function
We study the problem of morphing two polygons of building footprints at two different scales. This problem frequently occurs during the continuous zooming of interactive maps. The ground plan of a building footprint on a map has orthogonal characteristics, but traditional morphing methods cannot preserve these geographic characteristics at intermediate scales. We attempt to address this issue by presenting a turning angle function-based morphing model (TAFBM) that can generate polygons at an intermediate scale with an identical turning angle for each side. Thus, the orthogonal characteristics can be preserved during the entire interpolation. A case study demonstrates that the model yields good results when applied to data from a building map at various scales. During the continuous generalization, the orthogonal characteristics and their relationships with the spatial direction and topology are well preserve
Impact of Sensor Zenith Angle on MOD10A1 Data Reliability and Modification of Snow Cover Data for the Tarim River Basin
Snow in the mountainous watersheds of the Tarim River Basin is the primary source of water for western China. The Snow Cover Daily L3 Global 500-m Grid (MOD10A1) remote sensing dataset has proven extremely valuable for monitoring the changing snow cover patterns over large spatial areas; however, inherent uncertainty associated with large sensor zenith angles (SZAs) has called its reliability into question. Comparative analysis that utilized a paired-date difference method for parameters such as snow cover frequency, snow cover percentage, and normalized difference snow index (NDSI) has shown that overestimation of snow cover in the Tarim River Basin correlates with high values of SZA. Hence, such overestimation was associated with an increase in the NDSI, attributable to the change in reflectance between Band 4 and Band 6 imagery. A maximum threshold value of SZA of 22.37° was used alongside a multiday refilling method to modify the MOD10A1 dataset to produce a new daily snow cover map of the Tarim River Basin, spanning a 10-year period. A comparison of benchmark results of snow cover classification produced by the HJ-1A/B satellite revealed an increase in the overall accuracy of up to 4%, confirming the usefulness of our modified MOD10A1 data
Characteristics of warm season precipitating storms in the Arkansas–Red River basin
This is the publisher's version, also available electronically from http://onlinelibrary.wiley.com/doi/10.1029/2008JD011093/abstract.[1] Analysis of a multisensor precipitation product enables us to extract the precipitation from individual storms in the Arkansas–Red River drainage basin over a period of 11 years. We examine the year-to-year and intraseasonal variations of storm numbers, duration, sizes, and precipitation in the data set. Intraseasonal variations in numbers of storms exceed their year-to-year variations. More mountainous regions had greater numbers of storms than flatter regions. Most storms are small, last less than 2 h, and produce modest amounts of precipitation. The maximum size of storms and the number of storms are negatively correlated on a yearly basis. Midsummer months had a greater percentage of smaller storms but the storms were of longer average duration. We can roughly divide the storms into three different types, single ordinary cell storms, multiple storms (includes supercells), and mesoscale convective systems, and look at their year to year and intraseasonal variability in the data set. The most storms occur around 1700 local time but the most precipitation falls around 0100 local time. Storm duration was the most important factor determining how much precipitation storms generate per cell. We do not find that drought years or years with abundant precipitation had any particular characteristics but occur as a result of simultaneous occurrence of several features
Graph-based representation and analysis for storm events
This presentation was given as part of the GIS Day@KU symposium on November 18, 2015. For more information about GIS Day@KU activities, please see http://www.gis.ku.edu/gisday/2015/.Platinum Sponsors: KU Department of Geography and Atmospheric Science; KU School of Business.
Gold Sponsors: Bartlett & West; Kansas Biological Survey; KU Environmental Studies Program; KU Institute for Policy & Social Research; KU Libraries.
Silver Sponsors: State of Kansas Data Access and Support Center (DASC).
Bronze Sponsors: KU Center for Remote Sensing of Ice Sheets (CReSIS); TREKK Design Group, LLC; Wilson & Company, Engineers and Architects
Evolution of Ecological Security in the Tableland Region of the Chinese Loess Plateau Using a Remote-Sensing-Based Index
Maintaining optimal ecological security is a serious issue in the Chinese Loess Plateau (CLP). Remote sensing ecological indexes (RSEI) of three main tableland regions of the CLP were calculated based on spectral information provided by remote sensing imaging satellites between 2000 and 2018. We were able to use RSEI values to systematically evaluate the temporal and spatial variation in the regional ecological environment and determine the influential factors that mainly associated with these changes. The results showed that between 2000 and 2018, the ecological environment improved, remained stable, and deteriorated, respectively, in the Gansu, Shaanxi, and Shanxi tablelands. Regions with poor or fair RSEIs were concentrated around the main river basins, while regions with moderate RSEIs were associated with poor ecological conditions and poor areas. The significant spatiotemporal variation in RSEI indicates that the ecological system in this region is relatively fragile. We also observed that natural factors such as the temperature, potential evapotranspiration, and precipitation had the greatest influence on the overall ecological quality. The rapid increase in the regional population and human activity played an important role in the variation in the regional RSEI. This research will provide important information on controlling regional soil erosion and ecological restoration in the CLP
Recent advances in the climate change biology literature: describing the whole elephant
This is the publisher's version, also available electronically from http://onlinelibrary.wiley.com/doi/10.1002/wcc.59/abstract.Climate change biology is seeing a wave of new contributions, which are reviewed herein. Contributions treat shifts in phenology and distribution, and both document past and forecast future effects. However, many of the current wave of contributions are observational and correlational, and few are experimental in nature, and too often a conceptual framework in which to contextualize the results is lacking. An additional gap is the lack of effective cross-linking among areas of research, for example, connection of sea-level rise and climate change implications for distributions of species, or evolutionary adaptation studies with distributional shift studies. Although numerous important contributions have emerged in recent years, synthesis of this phenomenon and its consequences has not yet been achieved. Copyright © 2010 John Wiley & Sons, Ltd
Lake volume variation in the endorheic basin of the Tibetan Plateau from 1989 to 2019
Lake storage change serves as a unique indicator of natural climate change on the Tibetan Plateau (TP). However, comprehensive lake storage data, especially for lakes smaller than 10 km2, are still lacking in the region. In this dataset, we completed a census of annual relative lake volume (RLV) for 976 lakes, which are larger than 1 km2, on the endorheic basin of the Tibetan Plateau (EBTP) during 1989–2019 using Landsat imagery and digital terrain models. Our method first identifies individual lakes, determines their analysis extents and calculates annual lake area from Landsat imagery. It then derives lake area-elevation relationship, estimates lake surface elevation, and calculates RLV. Validation and comparison with several existing datasets indicate our data are more reliable and comprehensive. Our study complements existing lake datasets by providing a complete and long-term lake water volume change data for the region
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