A Survey of Applications of Wireless Sensors and Wireless Sensor Networks <s> A. Military applications <s> Networks of small, densely distributed wireless sensor nodes are being envisioned and developed for a variety of applications involving monitoring and the physical world in a tetherless fashion. Typically, each individual node can sense in multiple modalities but has limited communication and computation capabilities. Many challenges must be overcome before the concept of sensor networks In particular, there are two critical problems underlying successful operation of sensor networks: (1) efficient methods for exchanging information between the nodes and (2) collaborative signal processing (CSP) between the nodes to gather useful information about the physical world. This article describes the key ideas behind the CSP algorithms for distributed sensor networks being developed at the University of Wisconsin (UW). We also describe the basic ideas on how the CSP algorithms interface with the networking/routing algorithms being developed at Wisconsin (UW-API). We motivate the framework via the problem of detecting and tracking a single maneuvering target. This example illustrates the essential ideas behind the integration between UW-API and UW-CSP algorithms and also highlights the key aspects of detection and localization algorithms. We then build on these ideas to present our approach to tracking multiple targets that necessarily requires classification techniques becomes a reality. <s> BIB001 </s> A Survey of Applications of Wireless Sensors and Wireless Sensor Networks <s> A. Military applications <s> Distributed sensor networks are a significant technology nowadays. Inexpensive, smart devices with multiple sensors provide opportunities for instrumenting, monitoring and controlling targeting systems. Such sensor nodes have capability for acquiring and embedded-processing of variety of data forms. Collaborative signal processing and fusion algorithms are needed to aggregate the distributed data from among the nodes in the network, including possibly multiple modalities of data within a sensor node, to make decisions in a reliable and efficient manner. One of the important sensor network applications is target classification in battlefields. This paper presents improved moving vehicle target classification performance using data obtained from sensor networks with collaboration both across nodes and within a node in terms of multimodal fusion. Results show that a 50% relative improvement in classification error can be obtained using collaboration both in the case of single vehicle target and those involving multi-vehicle convoys. <s> BIB002 </s> A Survey of Applications of Wireless Sensors and Wireless Sensor Networks <s> A. Military applications <s> Sensor networks are gaining a central role in the research community. This paper addresses some of the issues arising from the use of sensor networks in control applications. Classical control theory proves to be insufficient in modeling distributed control problems where issues of communication delay, jitter, and time synchronization between components are not negligible. After discussing our hardware and software platform and our target application, we review useful models of computation and then suggest a mixed model for design, analysis, and synthesis of control algorithms within sensor networks. We present a hierarchical model composed of continuous time-trigger components at the low level and discrete event-triggered components at the high level. <s> BIB003 </s> A Survey of Applications of Wireless Sensors and Wireless Sensor Networks <s> A. Military applications <s> The focus of surveillance missions is to acquire and verify information about enemy capabilities and positions of hostile targets. Such missions often involve a high element of risk for human personnel and require a high degree of stealthiness. Hence, the ability to deploy unmanned surveillance missions, by using wireless sensor networks, is of great practical importance for the military. Because of the energy constraints of sensor devices, such systems necessitate an energy-aware design to ensure the longevity of surveillance missions. Solutions proposed recently for this type of system show promising results through simulations. However, the simplified assumptions they make about the system in the simulator often do not hold well in practice and energy consumption is narrowly accounted for within a single protocol. In this paper, we describe the design and implementation of a running system for energy-efficient surveillance. The system allows a group of cooperating sensor devices to detect and track the positions of moving vehicles in an energy-efficient and stealthy manner. We can trade off energy-awareness and surveillance performance by adaptively adjusting the sensitivity of the system. We evaluate the performance on a network of 70 MICA2 motes equipped with dual-axis magnetometers. Our results show that our surveillance strategy is adaptable and achieves a significant extension of network lifetime. Finally, we share lessons learned in building such a complete running system. <s> BIB004
Military applications are very closely related to the concept of wireless sensor networks. In fact, it is very difficult to say for sure whether motes were developed because of military and air defense needs or whether they were invented independently and were subsequently applied to army services. Regarding military applications, the area of interest extents from information collection, generally, to enemy tracking, battlefield surveillance or BIB001 , BIB002 . Classification algorithms use, for instance, input data that come from seismic and acoustic signal sensing. For example, mines may be regarded as dangerous and obsolete in the future and may be replaced by thousands of dispersed motes that will detect an intrusion of hostile units. Then, the prevention of intrusion will be the response of the defence system. An application related to this scenario, developed by the University of Virginia, is presented in BIB004 . Another demonstration, described in BIB003 deals with multi-vehicle tracking in the framework of a pursuitevasion game. There are two competitive teams: the pursuers and the evaders. A third part is a sensor network which is used to help pursuers locate their opponents. The sensor network informs the pursuers about the relative positions and movements of the enemy units. So, the sensors network augments the "vision" of the pursuer team and reveals their rivals. Ohio State University has also demonstrated an application of this kind. The name of this project is "A line in the Sand" [6] and refers to the deployment of ninety nodes which are capable of detecting metallic objects. The ultimate objective was the tracking and classification of moving objects with significant metallic content and specifically the tracking of vehicles and armed soldiers. Other beings (e.g. civilians) were ignored by the system. Finally, Palo Alto Research Center also tries to spot "interesting" vehicles (that is vehicles marked by a specific way as important) using motes equipped with microphones or steerable cameras  . The objective is to coordinate a number of this kind of sensors in order to keep sensing the track of a chosen moving object minimizing any information gaps about the track that may occur. In spite of the fact that the above research refers to wartime scenarios, its results can also be used during pace time. Peacetime applications such as homeland security, property protection and surveillance, border patrol, etc. are activities that perhaps in future sensors networks will undertake. The use of motes to improve the environmental conditions inside buildings has also preoccupied the American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE). A wireless network was deployed in an office building at Pacific Northwest National Laboratory, Richland, Washington, to survey the advantages and drawbacks of wireless technology in operation of heating, ventilation and air condition (HVAC) systems  ,  .