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Abstract-Wireless sensor networks (WSN) based on the IEEE 802.15.4 Personal Area Network standard are finding increasing use in the home automation and emerging smart energy markets. The network and application layers, based on the ZigBee 2007 PRO Standard, provide a convenient framework for component-based software that supports customer solutions from multiple vendors. This technology is supported by System-on-a-Chip solutions, resulting in extremely small and low-power nodes. The Wireless Connections in Space Project addresses the aerospace flight domain for both flight-critical and non-critical avionics. WSNs provide the inherent fault tolerance required for aerospace applications utilizing such technology. The team from Ames Research Center has developed techniques for assessing the fault tolerance of ZigBee WSNs challenged by radio frequency (RF) interference or WSN node failure. 1The ZigBee Network layer forms a mesh network capable of routing data around failed nodes. A two-tier ZigBee network is tested in the lab and various failures induced in sensor and router nodes, simulating realistic fault conditions. A ZigBee network analyzer is used to view the packet traffic and measure the response to these induced faults at the Network layer. Certain faults are induced using Radio Frequency (RF) interference or disruption of the Physical layer, so RF signal levels are monitored during the experiments. The speed at which an orphaned sensor node is detected and an alternative route formed is an important characteristic for fault-tolerant sensor networks. Our working definitions of metrics describing WSN fault tolerance are presented along with a summary of on-going test results from our development lab.A brief overview of ZigBee technology is presented along with RF measurement techniques designed to gauge susceptibility to interference caused by other transmitters such as wireless networks. Since 802.11 and 802.15.4 technology share the 2.4 GHz ISM band, spectrum management is used to ensure every network has a reasonably clear channel for communications. Quantitative RF characterization of the WSN is performed under varying duty cycle conditions to understand the effect of wireless networks and other interference sources on its performance. Furthermore, multipath interference caused by delayed reflections of RF signals is a significant issue, given that the WSN must run in confined metallic spaces, which produce 1 U.S. Government work not protected by U.S. copyright. IEEEAC Paper #1480, Version I, Updated December 9, 2010 high levels of reflected multipath RF energy. The results of RF characterization and interference testing of our prototype WSN in the lab are presented and summarized. The architecture and technical feasibility of creating a single fault-tolerant WSN for aerospace applications is introduced, based on our experimental findings.

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The abstract provides an overview of lymphedema, a chronic and progressive lymphatic disorder that affects millions of people globally. This condition is associated with high costs and comorbidity, with limited treatment options available. Phlebolymphedema, a common form of secondary lymphedema, is linked to the combined effects of lymphatic and chronic venous insufficiencies. Early intervention is crucial to managing the condition; however, early detection remains challenging due to the lack of reliable diagnostic tools. This case study evaluates the clinical utility of a portable tissue analytical tool in a subject with bilateral lower extremity lymphedema undergoing a 60-day self-management program. The study includes details of the subject's profile, the intervention, and the measurements taken with the novel tool.

Space Plug-and-Play Architecture (SPA), defined by the Air Force Research Laboratory, is a new standard for spacecraft component interconnections (AIAA-S-133-x-2013) providing new capability for managing intelligent components. Wireless Sensor Networks (WSN) based on the IEEE 802.15.4 Personal Area Network standard are finding increasing use in the home automation and emerging smart energy markets. The network protocol and application layers can be based on the ZigBee standard as defined by the ZigBee Alliance, providing a framework for component-based software that supports solutions from multiple vendors. SPA and ZigBee create selfconfiguring ad-hoc networks, but differ in their approach. SPA focuses on self-configuring components using wired interconnects while ZigBee forms self-configuring wireless networks. The optimal combination of SPA with ZigBee technology can bring the advantages of both methods to nextgeneration spacecraft by using self-configuring wireless networks for data and intelligent components with universal SPA-compliant interfaces. Mesh-enabled WSNs provide inherent fault tolerance and SPA provides dynamic fault management leading to low-power, low-cost ancillary sensing solutions for spacecraft. 1 Self-configuring architectures are the key for supporting a large number of sensors in dynamic configurations, allowing intelligent response for fault tolerant networks. Plug-and-Play for sensor networks could be defined as the capability for application software to query any sensor module connected to the ad-hoc dynamic network using module resident information defining the sensors characteristics. The embedding of sensor information into each Wireless Sensor Module (WSM) allows identifying each sensor unambiguously and accurately in terms of function and status, without the use of any configuration database. The IEEE 1451 Smart Transducer Interface Standard defines Transducer Electronic Datasheets (TEDS) containing key information regarding sensor characteristics such as name, description, serial number and calibration information. SPA defines an extensible format called xTEDS using XML embedded meta-information for sensor management enabling software to identify the sensor and interpret the sensor data stream without reference to any external information. The application software is able to read the status of each sensor module, responding in real-time to changes of WSN configuration and provide the appropriate response for maintaining overall sensor system function, even when sensor modules fail or the network is reconfigured. Temporal integrity of sensor data delivery is ensured by the use of a global network clock and embedding timestamps into each measurement result accurate to one millisecond. SPA provides high-level mechanisms for self-configuration and integration with other spacecraft components and can U.S. Government work not protected by U.S. copyright. significantly improve interoperability. The architecture and technical feasibility for creating wireless fault-tolerant sensor networ...