Localization is a critical issue in wireless sensor networks. In most localization schemes, there are beacons being placed as references to determine the positions of objects or events appearing in the sensing field. The underlying assumption is that beacons are always static. In this work, we define a new Beacon Movement Detection (BMD) problem. Assuming that there are unnoticed changes of locations of some beacons in the system, this problem is concerned about how to automatically monitor such situations and identify these beacons. Removal of such beacons in the positioning engine may improve the localization accuracy. Two schemes are proposed to solve the BMD problem. Finally, we evaluate how these solutions can improve the accuracy of localization schemes in case that there are unnoticed movement of some beacons. Simulation results show that our solutions alleviate 53% the decrease of positioning accuracy caused by the exceptional beacon movement.
In wireless sensor networks (WSN), a binding is an association between a sensor and an actuator. The binding mechanism defined in the ZigBee specification is restricted within a personal area network (PAN). For a complex WSN application, it is desired to have an inter-PAN binding mechanism to combine sensors and actuators from different PANs, respectively. In this paper, we have proposed a gateway-based inter-PAN binding mechanism for global event detection and action invocation. By collecting device capabilities from each intra-PAN gateway, an inter-PAN gateway is used to create a binding specification. Once all events defined in the binding specification are received from related intra-PAN gateways, the inter-PAN gateway would initiate corresponding actions on all associated intra-PAN gateways. To demonstrate the practicality, an inter-PAN binding system for ZigBee sensors and actuators has been implemented based on the universal plug and play (UPnP) and representational state transfer (REST) Web services for intra-PAN gateway discovery and device capability collection. Also, a Web-based wizard has been provided to create binding specification. It is believed that the technique presented in this paper would enable the interaction between ZigBee PANs to perform wide-ranging WSN applications.
A unique feature of sensor networks is the capability of performing actions in response to events detected by sensors. Such a feature requires a mechanism to create an association between the sensor and the actuator, and the resulting association is called a binding. The ZigBee specification defines default binding mechanism called end-device binding. However, this binding mechanism allows only a restricted range of combinations between sensors and actuators. Event filters cannot be defined using this mechanism as well. This paper proposes a flexible binding mechanism for ZigBee sensors called event-action binding, where sensors and actuators can be associated without the constraints imposed by the end-device binding. An event-action binding associates a specific event generated by a sensor with a specific action provided by an actuator. The mechanism supports event filters and multiple event filters can be combined as a composite filter. The binding mechanism was implemented for ZigBee sensors conforming to the specifications of ZigBee home automation and ZigBee cluster library. The implementation is based on YAML descriptions and provides an event matching engine and a browser-based user interface.
This paper presents the NTP experimental platform for heterogeneous wireless sensor networks (WSN), which is built on the campus of National Tsing Hua University under the support of the National Science and Technology Program for Telecommunications (NTP) in Taiwan. The unique purpose of this testbed is to provide an open platform for research communities to test and to showcase their WSN systems and applications. The heterogeneous testbed is composed of three different sensor platforms: the III Zigbee Advanced Platform, the ITRI Sensor Platform and the Moteiv Tmote Platform. A middleware architecture is developed to support contextaware services (CASs) and location-based services (LBSs) across different sensor platforms. Specifically, a SENSORINFO gateway is implemented to hide the discrepancy of different sensor platforms from application developers, which allows application developers to deploy their CASs and/or LBSs while being oblivious to the underlying sensor hardware or system architecture. Moreover, to facilitate the experiments, an over-the-air (OTA) remote update function is available on the platform to enable reprogramming of sensors from a remote location. To demonstrate the unique features of this platform, we present two sample applications: the People Tracking System and the Green Building Monitoring System, which are examples of the LBS and the CAS, respectively.
Abstract Background Cathepsin S (CTSS) is a cysteine protease that played diverse roles in immunity, tumor metastasis, aging and other pathological alterations. At the cellular level, increased CTSS levels have been associated with the secretion of pro-inflammatory cytokines and disrupted the homeostasis of Ca 2+ flux. Once CTSS was suppressed, elevated levels of anti-inflammatory cytokines and changes of Ca 2+ influx were observed. These findings have inspired us to explore the potential role of CTSS on cognitive functions. Methods We conducted classic Y-maze and Barnes Maze tests to assess the spatial and working memory of Ctss −/− mice, Ctss + / + mice and Ctss + / + mice injected with the CTSS inhibitor (RJW-58). Ex vivo analyses including long-term potentiation (LTP), Golgi staining, immunofluorescence staining of sectioned whole brain tissues obtained from experimental animals were conducted. Furthermore, molecular studies were carried out using cultured HT-22 cell line and primary cortical neurons that treated with RJW-58 to comprehensively assess the gene and protein expressions. Results Our findings reported that targeting cathepsin S (CTSS) yields improvements in cognitive function, enhancing both working and spatial memory in behavior models. Ex vivo studies showed elevated levels of long-term potentiation levels and increased synaptic complexity. Microarray analysis demonstrated that brain-derived neurotrophic factor (BDNF) was upregulated when CTSS was knocked down by using siRNA. Moreover, the pharmacological blockade of the CTSS enzymatic activity promoted BDNF expression in a dose- and time-dependent manner. Notably, the inhibition of CTSS was associated with increased neurogenesis in the murine dentate gyrus. These results suggested a promising role of CTSS modulation in cognitive enhancement and neurogenesis. Conclusion Our findings suggest a critical role of CTSS in the regulation of cognitive function by modulating the Ca 2+ influx, leading to enhanced activation of the BDNF/TrkB axis. Our study may provide a novel strategy for improving cognitive function by targeting CTSS.
This paper presents the NTP experimental platform for heterogeneous wireless sensor networks (WSN), which is built on the campus of National Tsing Hua University under the support of the National Science and Technology Program for Telecommunications (NTP) in Taiwan. The unique purpose of this testbe
For outdoor localization, GPS already provides a satisfactory solution. For indoor localization, however, a globally usable solution is still missing. One promising direction that is proposed recently is the fingerprinting-based solution. It involves a training phase to collect the radio signal strength (RSS) patterns in fields where localization is needed into a database (called radio map). The radio signal could be from WiFi access points, GSM base stations, or other RF-based networks. Then, during the positioning phase, an object which is interested in its own location can collect its current RSS pattern and compare it against the radio map established in the training phase to identify its possible location. We present an interesting system based a robot and numerous cheap RFID tags deployed on the ground to automate the training process and, more importantly, to frequently update radio maps to reflect the current RSS patterns. This not only significantly reduces human labors but also improves positioning accuracy.
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