447 research outputs found

    Investigation of passive atmospheric sounding using millimeter and submillimeter wavelength channels

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    Activities within the period from July 1, 1992 through December 31, 1992 by Georgia Tech researchers in millimeter and submillimeter wavelength tropospheric remote sensing have been centered around the calibration of the Millimeter-wave Imaging Radiometer (MIR), preliminary flight data analysis, and preparation for TOGA/COARE. The MIR instrument is a joint project between NASA/GSFC and Georgia Tech. In the current configuration, the MIR has channels at 90, 150, 183(+/-1,3,7), and 220 GHz. Provisions for three additional channels at 325(+/-1,3) and 8 GHz have been made, and a 325-GHz receiver is currently being built by the ZAX Millimeter Wave Corporation for use in the MIR. Past Georgia Tech contributions to the MIR and its related scientific uses have included basic system design studies, performance analyses, and circuit and radiometric load design, in-flight software, and post-flight data display software. The combination of the above millimeter wave and submillimeter wave channels aboard a single well-calibrated instrument will provide unique radiometric data for radiative transfer and cloud and water vapor retrieval studies. A paper by the PI discussing the potential benefits of passive millimeter and submillimeter wave observations for cloud, water vapor and precipitation measurements has recently been published, and is included as an appendix

    Investigation of passive atmospheric sounding using millimeter and submillimeter wavelength channels

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    Activities within the period from January 1, 1992 through June 30, 1992 by Georgia Tech researchers in millimeter and submillimeter wavelength tropospheric remote sensing have been centered around the integration and initial data flights of the MIR on board the NASA ER-2. Georgia Tech contributions during this period include completion of the MIR flight software and implementation of a 'quick-view' graphics program for ground based calibration and analysis of the MIR imagery. In the current configuration, the MIR has channels at 90, 150, 183 +/- 1,3,7, and 220 GHz. Provisions for three additional channels at 325 +/-1,3 and 9 GHZ have been made, and a 325-GHz receiver is currently being built by the ZAX Millimeter Wave Corporation for use in the MIR. The combination of the millimeter wave and submillimeter wave channels aboard a single well-calibrated instrument will provide the necessary aircraft radiometric data for radiative transfer and cloud and water vapor retrieval studies. A paper by the PI discussing the potential benefits of passive millimeter and submillimeter wave observations for cloud, water vapor and precipitation measurements has recently been accepted for publication (Gasiewski, 1992), and is included as Appendix A. The MIR instrument is a joint project between NASA/GSFC and Georgia Tech. Other Georgia Tech contributions to the MIR and its related scientific uses have included basic system design studies, performance analyses, and circuit and radiometric load design

    Self-supervised automated wrapper generation for weblog data extraction

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    Data extraction from the web is notoriously hard. Of the types of resources available on the web, weblogs are becoming increasingly important due to the continued growth of the blogosphere, but remain poorly explored. Past approaches to data extraction from weblogs have often involved manual intervention and suffer from low scalability. This paper proposes a fully automated information extraction methodology based on the use of web feeds and processing of HTML. The approach includes a model for generating a wrapper that exploits web feeds for deriving a set of extraction rules automatically. Instead of performing a pairwise comparison between posts, the model matches the values of the web feeds against their corresponding HTML elements retrieved from multiple weblog posts. It adopts a probabilistic approach for deriving a set of rules and automating the process of wrapper generation. An evaluation of the model is conducted on a dataset of 2,393 posts and the results (92% accuracy) show that the proposed technique enables robust extraction of weblog properties and can be applied across the blogosphere for applications such as improved information retrieval and more robust web preservation initiatives

    On Building Distributed Soft Real-Time Systems

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    When building a distributed real-time system, one can either build the whole system from scratch, or from pre-existing standard components. Although the former allows better scheduling design, it may not be economical in terms of the cost and time of development. This paper studies the performance of distributed soft real-time systems that use standard components with various scheduling algorithms and suggests ways to improve them.published_or_final_versio

    Maintaining temporal consistency of discrete objects in soft real-time database systems

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    A real-time database system contains base data items which record and model a physical, real-world environment. For better decision support, base data items are summarized and correlated to derive views. These base data and views are accessed by application transactions to generate the ultimate actions taken by the system. As the environment changes, updates are applied to base data, which subsequently trigger view recomputations. There are thus three types of activities: Base data update, view recomputation, and transaction execution. In a real-time database system, two timing constraints need to be enforced. We require that transactions meet their deadlines (transaction timeliness) and read fresh data (data timeliness). In this paper, we define the concept of absolute and relative temporal consistency from the perspective of transactions for discrete data objects. We address the important issue of transaction scheduling among the three types of activities such that the two timing requirements can be met. We also discuss how a real-time database system should be designed to enforce different levels of temporal consistency.published_or_final_versio

    Mass Handling of Watermelon Microcuttings

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    Modifications were made in the configurations of the unitizing, nonselective wire cutters used by Alper et al.(1992) for mass cuttings of Stage II Citrullus lanatus cv. Charlee (watermelon) plant tissue cultures to further enhance productivity. Mounting the cutter in an inverted position over the receiving vessel eliminated time required for filling. This cut-and-dump technique became 4.8 times more productive for the total transfer process than the conventional scalpel and forceps technique when both time and yield of cut segments with visible buds were considered. A concept for growing fewer, larger tissue clusters per vessel in mini-trays with orienting cells and cutting with correspondingly sized orientedcell wire cutters yielded as much tissue fresh weight as conventional agar vessels and afforded the potential to reduce time required for the removal job function with the cut-and-dump technique

    Unitized, Nonselective Cutting of In Vitro Watermelon

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    Unitized, nonselective mass cutting of Stage II Citrullus lanatus cv. Charlee (watermelon) plant tissue cultures has been achieved with various configurations and sizes of wire cutter devices. Time studies revealed that the wire cutters increased the productivity of the cutting function over conventional scalpel and forceps by a factor of 14, Total transfer productivity, including the manual functions of removing tissue from an initial culture vessel and filling (sorting and placing cut tissue segments) new vessels, was increased by a factor of 1,8, The square grid-type cutting devices yielded from 48 to 59% as many viable bud clusters per culture vessel as hand cutting and from 65 to 95% as much tissue fresh weight. An oriented-cell configuration of wire cutter actually increased tissue fresh weight about 20% over hand cutting. The simplicity of construction and quality of material of the wire cutter render it readily autoclavable and highly flexible to function both as an aid to small operations and as an element in more sophisticated mechanical devices for larger operations

    Investigation of passive atmospheric sounding using millimeter and submillimeter wavelength channels

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    Progress by investigators at the Georgia Institute of Technology in the development of techniques for passive microwave retrieval of water vapor, cloud, and precipitation parameters using millimeter- and sub-millimeter wavelength channels is reviewed. Channels of particular interest are in the tropospheric transmission windows at 90, 166, 220, 340, and 410 GHz and centered around the water vapor lines at 183 and 325 GHz. Collectively, these channels have potential application in high-resolution mapping (e.g., from geosynchronous orbit), remote sensing of cloud and precipitation parameters, and retrieval of water vapor profiles. During the period from 1 Jan. 1993 through 30 Jun. 1993 the Millimeter-wave Imaging Radiometer (MIR) completed data flights during a two-month long deployment in conjunction with TOGA/COARE. Coincident data was collected from several other ground-based, airborne, and satellite sensors, including the NASA/MSFC AMPR, MIT MTS, DMSP SSM/T-2 satellite, collocated radiosondes, ground- and aircraft-based radiometers and cloud lidars, airborne infrared imagers, solar flux probes, and airborne cloud particle sampling probes

    Support for graphicacy: a review of textbooks available to accounting students

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    This Teaching Note reports on the support available in textbooks for graphicacy that will help students understand the complexities of graphical displays. Graphical displays play a significant role in financial reporting, and studies have found evidence of measurement distortion and selection bias. To understand the complexities of graphical displays, students need a sound understanding of graphicacy and support from the textbooks available to them to develop that understanding. The Teaching Note reports on a survey that examined the textbooks available to students attending two Scottish universities. The support of critical graphicacy skills was examined in conjunction with textbook characteristics. The survey, which was not restricted to textbooks designated as required reading, examined the textbooks for content on data measurement and graphical displays. The findings highlight a lack of support for graphicacy in the textbooks selected. The study concludes that accounting educators need to scrutinize more closely the selection of textbooks and calls for more extensive research into textbooks as a pedagogic tool
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