461 research outputs found

    THE NEXT GENERATION OF WILDLAND FIREFIGHTING TOOLS: USING UAV SWARMS FOR FIRE ATTACK

    Get PDF
    Wildland fires pose a direct threat to homeland security because of the severe personal, economic, and social stress they cause to those affected. As unmanned aerial vehicle (UAV) swarms become more ubiquitous in use, they will likely find a place as a frontline firefighting aerial asset, increasing the operational pace of aerial suppression flights and consequently increasing the safety of firefighters. This thesis explored the concept of using UAV swarms as a method for fire attack by comparing theoretical swarms to a conventional aerial asset within a realistic fire scenario and then using a systems engineering approach to define pressure points for implementing UAV swarms in the wildland space. The findings of this research support continued development of UAV swarms and clearly define areas that must be addressed before implementing large-scale UAV swarm flights. The firefighting UAV swarm system shows great promise due to its relative portability and ability to provide an aerial firefighting option to areas without ready access to conventional firefighting aircraft. It will be critical, however, to address logistical and communications constraints of UAV swarm systems before implementation to ensure positive outcomes.Civilian, Portland Fire and RescueApproved for public release. Distribution is unlimited

    College Students’ Online Speech: Searching for the Appropriate Standards Within First Amendment Case Principles

    Get PDF
    College student free speech cases, particularly as applied to student online speech challenges, suffer from conflicting legal principles. This paper highlights empirically noted problems in resolving disputes between a college student’s free speech rights and a public college’s authority to maintain order and campus safety. In Part I of this paper, the authors present the established legal principles from two foundational cases addressing issues of student speech in the educational context. In Part II, the authors demonstrate how courts have used PK12 education cases and public employment cases as sources that address legal principles for college student speech cases—particularly to resolve college students’ speech challenges with an online dimension. In Part III, the authors conclude that existing legal principles, ones largely derived from the PK12 education context, are insufficient to analyze some types of student collegiate speech cases. This thesis is supported when examining several cases involving college students, especially cases dealing with college students’ online speech or expression. In resolving the legal framework problem, the authors suggest a modification of existing legal principles that accounts sufficiently for characteristics specific to the collegiate learning space

    Implanted miniaturized antenna for brain computer interface applications: Analysis and design

    Get PDF
    Implantable Brain Computer Interfaces (BCIs) are designed to provide real-time control signals for prosthetic devices, study brain function, and/or restore sensory information lost as a result of injury or disease. Using Radio Frequency (RF) to wirelessly power a BCI could widely extend the number of applications and increase chronic in-vivo viability. However, due to the limited size and the electromagnetic loss of human brain tissues, implanted miniaturized antennas suffer low radiation efficiency. This work presents simulations, analysis and designs of implanted antennas for a wireless implantable RF-powered brain computer interface application. The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance. The proper selection of the dielectric properties of the biocompatible insulating layers and the implantation position inside human brain tissues can facilitate efficient RF power reception by the implanted antenna. While the results show that the effects of the human head shape on implanted antenna performance is somewhat negligible, the constitutive properties of the brain tissues surrounding the implanted antenna can significantly impact the electrical characteristics (input impedance, and operational frequency) of the implanted antenna. Three miniaturized antenna designs are simulated and demonstrate that maximum RF power of up to 1.8 milli-Watts can be received at 2 GHz when the antenna implanted around the dura, without violating the Specific Absorption Rate (SAR) limits. © 2014 Zhao et al

    Life Testing of the Vapor Compression Distillation/Urine Processing Assembly (VCD/UPA) at the Marshall Space Flight Center (1993 to 1997)

    Get PDF
    Wastewater and urine generated on the International Space Station will be processed to recover pure water using vapor compression distillation (VCD). To verify the long-term reliability and performance of the VCD Urine Processor Assembly (UPA), life testing was performed at the Marshall Space Flight Center (MSFC) from January 1993 to April 1996. Two UPA'S, the VCD-5 and VCD-5A, were tested for 204 days and 665 days, respectively. The compressor gears and the distillation centrifuge drive belt were found to have operating lives of approximately 4,800 hours, equivalent to 3.9 years of operation on ISS for a crew of three at an average processing rate of 1.76 kg/h (3.97 lb/h). Precise alignment of the flex-splines of the fluids and purge pump motor drives is essential to avoid premature failure after about 400 hours of operation. Results indicate that, with some design and procedural modifications and suitable quality control, the required performance and operational life can be met with the VCD/UPA

    Axoneme-specific β-tubulin specialization a conserved C-terminal motif specifies the central pair

    Get PDF
    AbstractAxonemes are ancient organelles that mediate motility of cilia and flagella in animals, plants, and protists. The long evolutionary conservation of axoneme architecture, a cylinder of nine doublet microtubules surrounding a central pair of singlet microtubules, suggests all motile axonemes may share common assembly mechanisms. Consistent with this, α- and β-tubulins utilized in motile axonemes fall among the most conserved tubulin sequences [1, 2], and the β-tubulins contain a sequence motif at the same position in the carboxyl terminus [3]. Axoneme doublet microtubules are initiated from the corresponding triplet microtubules of the basal body [4], but the large macromolecular “central apparatus” that includes the central pair microtubules and associated structures [5] is a specialization unique to motile axonemes. In Drosophila spermatogenesis, basal bodies and axonemes utilize the same α-tubulin but different β-tubulins [6–13]. β1 is utilized for the centriole/basal body, and β2 is utilized for the motile sperm tail axoneme. β2 contains the motile axoneme-specific sequence motif, but β1 does not [3]. Here, we show that the “axoneme motif” specifies the central pair. β1 can provide partial function for axoneme assembly but cannot make the central microtubules [14]. Introducing the axoneme motif into the β1 carboxyl terminus, a two amino acid change, conferred upon β1 the ability to assemble 9 + 2 axonemes. This finding explains the conservation of the axoneme-specific sequence motif through 1.5 billion years of evolution

    Implementation of environmentally compliant cleaning and insulation bonding for MNASA

    Get PDF
    Historically, many subscale and full-scale rocket motors have employed environmentally and physiologically harmful chemicals during the manufacturing process. This program examines the synergy and interdependency between environmentally acceptable materials for solid rocket motor insulation applications, bonding, corrosion inhibiting, painting, priming, and cleaning, and then implements new materials and processes in subscale motors. Tests have been conducted to eliminate or minimize hazardous chemicals used in the manufacture of modified-NASA materials test motor (MNASA) components and identify alternate materials and/or processes following NASA Operational Environmental Team (NOET) priorities. This presentation describes implementation of high pressure water refurbishment cleaning, aqueous precision cleaning using both Brulin 815 GD and Jettacin, and insulation case bonding using ozone depleting chemical (ODC) compliant primers and adhesives

    Technical assessment of Mir-1 life support hardware for the international space station

    Get PDF
    NASA has been progressively learning the design and performance of the Russian life support systems utilized in their Mir space station. In 1992, a plan was implemented to assess the benefits of the Mir-1 life support systems to the Freedom program. Three primary tasks focused on: evaluating the operational Mir-1 support technologies and understanding if specific Russian systems could be directly utilized on the American space station and if Russian technology design information could prove useful in improving the current design of the planned American life support equipment; evaluating the ongoing Russian life support technology development activities to determine areas of potential long-term application to the U.S. space station; and utilizing the expertise of their space station life support systems to evaluate the benefits to the current U.S. space station program which included the integration of the Russian Mir-1 designs with the U.S. designs to support a crew of six
    • …
    corecore