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Battery energy management and optimization are of significant importance to self-sustained wireless sensor networks (WSNs) that use solar energy harvesting instead of fixed power supply as the charging source. In this paper, an optimal control strategy for WSNs with solar energy supply is proposed. A modified Kinetic Battery Model (KBM) considering charging input is introduced to account for the dynamic...
One of the primary energy consumers in buildings are the Heating, Ventilation, and Air-Conditioning (HVAC) systems, which usually operate on a fixed schedule, i.e., running from early morning until late evening during the weekdays. This fixed operation schedule does not take the dynamics of occupancy level in the building into consideration, therefore may lead to waste of energy. An estimate of the...
Measurement of human physical activity (PA) is important for assessing the health state. A wireless multi-senor integrated measurement system (WIMS) has been designed for measurement of the activity types and intensities of human subjects under free-living conditions. To address challenges posted by the limited battery life and asynchronous data among multiple sensors in the WIMS system, a ZigBee-based...
This paper presents an energy-efficient method for data transmission through improved data compression. This is achieved by a new signal source coding method based on the Walsh transform. This research is motivated by the need for extended service life of wireless sensor networks, where individual sensor nodes are energy constrained. Theoretical background is introduced, and its effectiveness is established...
Physical activity (PA) is important for assessing human exposure to the environment. This paper presents a ZigBee-based Wireless wearable multi-sensor Integrated Measurement System (WIMS) for in-situ PA measurement. Two accelerometers, a piezoelectric displacement sensor, and an ultraviolet (UV) sensor have been used for the physical activity assessment. Detailed analysis was performed for the hardware...
On-line monitoring of polymer melt state is critical to ensuring part quality in injection molding. This paper presents the design of a dual-parameter acoustic wireless sensor for simultaneous measurement of pressure and temperature variations within the mold cavity. The sensor consists of three major functional components: a piezoceramic energy harvester, a modulator circuit, and an electric-acoustic...
This paper presents an energy-efficient method for data transmission through improved data compression, based on the Walsh transform. The research is motivated by the need for optimal service life of wireless sensor networks, where individual sensor nodes are constrained by limited energy resources. A method of dynamically scaling sensor signals utilizing Walsh functions for data compression is presented...
This paper presents the design and evaluation of a novel adaptive sampling algorithm for reducing energy consumption in data acquisition and communication subsystems of a wireless sensor node. The algorithm uses isochronous measurements of the frequency content of the signal as the basis for adaptively varying the sampling rate. This allows signal acquisition at the minimum rate without sacrificing...
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