DOAS: A Drought Online Analysis System with Constraint Databases
نویسندگان
چکیده
The Standardized Precipitation Index (SPI) [5] is a common and simple measure of the intensity and duration of drought at certain measured point locations. We interpolate this original point-based SPI data using a shape function-based interpolation [3], which is the most accurate among a number of alternatives [2], and represent the result in a constraint database [1, 6]. A drought event occurs any time the SPI is continuously negative and reaches an intensity of −1 or less, and it ends when the SPI becomes positive [5]. This recursive definition is difficult for most database systems to implement and visualize. The Drought Online Analysis System (DOAS) uses a constraint database to represent the spatio-temporal data and allows both SQL and recursive, namely Datalog, queries which are high-level and easy to maintain. DOAS is a server-based and three-tier spatio-temporal system and supports animation of spatio-temporal results.
منابع مشابه
Emission Flux Measurement Error with a Mobile DOAS System and Application to NOx Flux Observations
Mobile differential optical absorption spectroscopy (mobile DOAS) is an optical remote sensing method that can rapidly measure trace gas emission flux from air pollution sources (such as power plants, industrial areas, and cities) in real time. Generally, mobile DOAS is influenced by wind, drive velocity, and other factors, especially in the usage of wind field when the emission flux in a mobil...
متن کاملDOASIS: a framework design for DOAS
The Differential Optical Absorption Spectroscopy (DOAS) is a simple, sensitive and robust method to measure trace gas concentrations by analyzing the spectrum of light that has passed through the atmosphere. Due to these advantages, DOAS gains more and more popularity for environmental monitoring in both cities and on a global scale. To use DOAS, an efficient software basis is necessary. The ex...
متن کاملAn Investigation of Information Seeking Behavior of Graduate Students of Kharazmi University in Writeing Dissertation
Background and Aim: These days, Internet and online databases play a significant role in peoples’ information-seeking behavior, especially for postgraduate students. The kind of behavior seen on the part of those students who get help from online databases to write their theses might be completely different from those who search library sources to get the needed information. This study invest...
متن کاملDeveloping optimal operating reservoir rule-curves in drought periods
In this study a simulation-optimization model is developed for deriving operation rule-curves in drought periods. To each reservoir, two rule-curves with adjustable monthly levels are introduced dividing the reservoir capacity into three zones between the normal water level and minimum operation level. To each zone of a reservoir and for each month of the year a hedging coefficient is introd...
متن کاملWhole-transcriptome sequence analysis of differentially expressed genes in Phormium tenax under drought stress
Phormium tenax is a kind of drought resistant garden plant with its rich and colorful leaves. To clarify the molecular mechanism of drought resistance in Phormium tenax, transcriptome was sequenced by the Illumina sequencing technology under normal and drought stress, respectively. A large number of contigs, transcripts and unigenes were obtained. Among them, only 30,814 unigenes were annotated...
متن کامل