Collaborative Workspaces within Distributed Virtual Environments

In warfare, be it a training simulation or actual combat, a commander\u27s time is one of the most valuable and fleeting resources of a military unit. Thus, it is natural for a unit to have a plethora of personnel to analyze and filter information to the decision-maker. This dynamic exchange of ideas between analyst and commander is currently not available within the distributed interactive simulation (DIS) community. This lack of exchange limits the usefulness of the DIS experience to the commander and his troops. This thesis addresses the commander\u27s isolation problem through the integration of a collaborative workspace within AFIT\u27s Synthetic BattleBridge (SBB) as a technique to improve situational awareness. The SBB\u27s Collaborative Workspace enhances battlespace awareness through CSCW (computer supported cooperative work) enabling communication technologies. The SBB\u27s Collaborative Workspace allows the user to interact with other SBB users through the transmission and reception of public bulletins, private email, real-time chat sessions, shared viewpoints, shared video, and shared annotations to the virtual environment. Collaborative communication between SBB occurs through the use of standard and experimental DIS-compliant protocol data units. The SBB\u27s Collaborative Workspace gives the battlespace commander the widest range of communication options available within a DIS virtual environment today

Location and mapping of 2.4 GHz RF transmitters

This paper describes the use of a MetaGeek WiSpy dongle in conjunction with custom developed client-server software for the accurate identication of Wireless nodes within an organisation. The MetaGeek WiSpy dongle together with the custom developed software allow for the determination of the positions of Wi-Fi transceivers to within a few meters, which can be helpful in reducing the area for physical searches in the event of rogue units. This paper describes the tool and methodology for a site survey as a component that can be used in organisations wishing to audit their environments for wireless networks. The tool produced from this project, the WiSpy Signal Source Mapping Tool, is a three part application based on a client-server architecture. One part interfaces with a low cost 2.4 GHz spectrum analyser, another stores the data collected from all the spectrum analysers and the last part interprets the data to provide a graphical overview of the Wi-Fi network being analysed. The location of the spectrum analysers are entered as GPS points, and the tool can interface with a GPS device to automatically update its geographical location. The graphical representation of the 2.4 GHz spectrum populated with Wi-Fi devices (Wi-Fi network) provided a fairly accurate method in locating and tracking 2.4 GHz devices. Accuracy of the WiSpy Signal Source Mapping Tool is hindered by obstructions or interferences within the area or non line of sight

Sediment Management for Southern California Mountians, Coastal Plains and Shoreline. Part D: Special Inland Studies

In southern California the natural environmental system involves the continual relocation of sedimentary materials. Particles are eroded from inland areas where there is sufficient relief and, precipitation. Then, with reductions in hydraulic gradient along the stream course and at the shoreline, the velocity of surface runoff is reduced and there is deposition. Generally, coarse sand, gravel and larger particles are deposited near the base of the eroding surfaces (mountains and hills) and the finer sediments are deposited on floodplains, in bays or lagoons, and at the shoreline as delta deposits. Very fine silt and clay particles, which make up a significant part of the eroded material, are carried offshore where they eventually deposit in deeper areas. Sand deposited at the shoreline is gradually moved along the coast by waves and currents, and provides nourishment for local beaches. However, eventually much of this littoral material is also lost to offshore areas. Human developments in the coastal region have substantially altered the natural sedimentary processes, through changes in land use, the harvesting of natural resources (logging, grazing, and sand and gravel mining); the construction and operation of water conservation facilities and flood control structures; and coastal developments. In almost all cases these developments have grown out of recognized needs and have well served their primary purpose. At the time possible deleterious effects on the local or regional sediment balance were generally unforeseen or were felt to be of secondary importance. In 1975 a large-scale study of inland and coastal sedimentation processes in southern California was initiated by the Environmental Quality Laboratory at the California Institute of Technology and the Center for Coastal Studies at Scripps Institution of Oceanography. This volume is one of a series of reports from this study. Using existing data bases, this series attempts to define quantitatively inland and coastal sedimentation processes and identify the effects man has had on these processes. To resolve some issues related to long-term sediment management, additional research and data will be needed. In the series there are four Caltech reports that provide supporting studies for the summary report (EQL Report No. 17). These reports include: EQL Report 17-A Regional Geological History EQL Report 17-B Inland Sediment Movements by Natural Processes EQL Report 17-C Coastal Sediment Delivery by Major Rivers in Southern California EQL Report 17-D -- Special Inland Studies Additional supporting reports on coastal studies (shoreline sedimentation processes, control structures, dredging, etc.) are being published by the Center for Coastal Studies at Scripps Institution of Oceanography, La Jolla, California

Mapping the location of 2.4 GHz transmitters to achieve optimal usage of an IEEE 802.11 network

This paper describes the use of a low cost 2.4 GHz spectrum analyser, the MetaGeek WiSpy device, in conjunction with custom developed client-server software for the accurate identification of 2.4 GHz transmitters within a given area. The WiSpy dongle together with the custom developed software allow for determination of the positions of Wi-Fi transmitters to within a few meters, which can be helpful in reducing the work load for physical searches in the process of surveying the Wi-Fi network and geographical area. This paper describes the tool and methodology for a site survey as a component that can be used in organisations wishing to audit their environments for Wi-Fi networks. The tool produced from this project, the WiSpy Signal Source Mapping Tool, is a three part application based on a client-server architecture. One part interfaces with a low cost 2.4 GHz spectrum analyser, another stores the data collected from all the spectrum analysers and the third part interprets the data to provide a graphical overview of the Wi-Fi network being analysed. The location of the spectrum analysers are entered as GPS points, and the tool can interface with a GPS device to automatically update its geographical location. The graphical representation of the 2.4 GHz spectrum populated with Wi-Fi devices (Wi-Fi network) provided a fairly accurate method in locating and tracking 2.4 GHz devices. Accuracy of the WiSpy Signal Source Mapping Tool is hindered by obstructions, interferences within the area or non line of sight

An Estimate of the Soil Fertility Status of Graves and Todd Counties in Kentucky

Some concern has developed during recent years that fertilizer is being used by farmers on fields with residual levels of P and K high enough that such use is not justified as a means of increasing crop yields. This has been due to increased average soil test values for samples routinely submitted to college soil test laboratories. For this reason, studies were conducted in Graves and Todd Counties in Kentucky during the period September, 1978 to September, 1980, to determine if soil samples routinely submitted to college test laboratories do or do not accurately reflect the average soil fertility status of a county

Growth, Yield, and Efficiency of Potassium Fertilizer Use in Burley Tobacco Production

For many crops, band placement of fertilizer offers agronomic, economic, and environmental advantages over commonly used preplant broadcast applications. Drill banding most of the nitrogen (N) fertilizer 12 inches to both sides of the row for tobacco shortly after transplanting greatly aIleviates manganese toxicity and other nutrient imbalances, improves early growth and yield, and offers increased efficiency of N use. Nitrogen fertilizers applied after transplanting are less likely to be leached during excess rainfall events that commonly occur in April and early May in Kentucky

Ecological integrity and western water management: a Colorado perspective

Sept. 1995.Includes bibliographical references

External Enrichment of Minihalos by the First Supernovae

Recent high-resolution simulations of early structure formation have shown that externally enriched halos may form some of the first metal enriched stars. This study utilizes a 1 comoving Mpc$^3$ high-resolution simulation to study the enrichment process of metal-enriched halos down to $z=9.3$. Our simulation uniquely tracks the metals ejected from Population III stars, and we use this information to identify the origin of metals within metal-enriched halos. These halos show a wide range of metallicities, but we find that the source of metals for $\gtrsim$ 50\% of metal-enriched halos is supernova explosions of Population III stars occuring outside their virial radii. The results presented here indicate that external enrichment by metal-free stars dominates the enrichment process of halos with virial mass below $10^{6}\,M_\odot$ down to $z=9.3$. Despite the prevalence of external enrichment in low mass halos, Pop II stars forming due to external enrichment are rare because of the small contribution of low-mass halos to the global star formation rate combined with low metallicities towards the center of these halos resulting from metal ejecta from external sources mixing from the outside-in. The enriched stars that do form through this process have absolute metallicities below $10^{-3}\,Z_\odot$. We also find that the fraction of externally enriched halos increases with time, $\sim 90\%$ of halos that are externally enriched have $M_\mathrm{vir} < 10^6\,M_\odot$, and that pair-instability supernovae contribute the most to the enrichment of the IGM as a whole and are thus are the predominant supernova type contributing to the external enrichment of halos.Comment: 15 pages, 12 figures, Accepted for publication in Ap

Optical assessment of pathology in surgically resected tissues

Multi-spectral spatially modulated light is used to guide localized spectroscopy of surgically resected tissues for cancer involvement. Modulated imaging rapidly quantifies near-infrared optical parameters with sub-millimeter resolution over the entire field for identification of residual disease in resected tissues. Suspicious lesions are further evaluated using a spectroscopy platform designed to image thick tissue samples at a spatial resolution sensitive to the diagnostic gold standard, pathology. MI employs a spatial frequency domain sampling and model-based analysis of the spatial modulation transfer function to interpret a tissue's absorption and scattering parameters at depth. The spectroscopy platform employs a scanning-beam, telecentric dark-field illumination and confocal detection to image fields up to 1cm2 with a broadband source (480:750nm). The sampling spot size (100μm lateral resolution) confines the volume of tissue probed to within a few transport pathlengths so that multiple-scattering effects are minimized and simple empirical models may be used to analyze spectra. Localized spectroscopy of Intralipid and hemoglobin phantoms demonstrate insensitivity of recovered scattering parameters to changes in absorption, but a non-linear dependence of scattering power on Intralipid concentration is observed due to the phase sensitivity of the measurement system. Both systems were validated independently in phantom and murine studies. Ongoing work focuses on assessing the combined utility of these systems to identify cancer involvement in vitro, particularly in the margins of resected breast tumors