The IEEE 802. 15. 4 standard defines a Physical (PHY) and Medium Access Control (MAC) layer protocol for low data rate wireless network with low power requirement which makes it ideal PHY/MAC for WSNs. Currently WSNs with combination of IEEE 802. 15. 4 and ZigBee are being used extensively in industrial applications such as factory automation and control, environmental monitoring etc. Such appl...

Low delay and long lifetime are a very important issue for industrial wireless sensor networks (IWSNs) in which it require long-time monitoring of industrial sites and respond quickly to events that is monitored; therefore, high delay communications can cause serious damage to property and personnel at industrial field. Due to delay, lifetime, and other performance involved to multiple layers, ...

Wireless sensor networks are used in many environmental monitoring applications (e.g., to monitor forest fires or volcanoes). In such applications, sensor nodes have a limited quantity of energy, but must operate for years without having their batteries changed. The main mechanism used to allow nodes to save energy is to sequence periods of activity and inactivity. However, the design of MAC an...

The use of time-frequency entropy to quantitatively assess the stability of alternating current square wave submerged arc welding process considering the distribution features of arc energy is reported in this paper. Time-frequency entropy is employed to calculate and analyze the current signals under different duty cycle, frequency and welding speed in the submerged arc welding process. It is ...

The clock distribution and generation circuitry forms a critical component of current synchronous digital systems. A digital system’s clocks must have not only low jitter, low skew, but also well-controlled duty cycle in order to facilitate versatile clocking techniques. In high-speed CMOS clock buffer design, the duty cycle of a clock is liable to be changed when the clock passes through a mul...

Duty cycle control is applied in IEEE 802.15.4 medium access control (MAC) protocol to reduce energy consumption. A low duty cycle improves the energy efficiency but it reduces the available transmission time, thereby increases the end-to-end delay. Thus, it is a challenge issue to achieve a good trade-off between energy efficiency and delay. In this paper, we study a duty cycle control problem...

In this communication, hexapod tripod gaits for straightline motion and crab walking are derived. Mathematical relations that express the stability margin, the stride length, and the duty factor are formulated for straight-line motion and for crab walking, respectively. The derived results provide tripod gaits of the hexapod for walking with a prescribed stability margin either over perfect ter...

Quorum-based schemes, e.g., GQS, can ensure asynchronous neighbors to discover each other within bounded time under low-duty-cycle operations. But they are tightly based on the assumption that duty cycles of devices fit some specific prefixed patterns. We tackle this problem by proposing a distributed quorum system to speed up the discovery.

Energy conservation is a major issue in the management of sensor networks. In this paper, we consider the problem of optimising the performance of energy-constrained sensor networks in the context of event detection applications, with the performance metric being a weighted average of the numbers of missed events and false alarms. We propose two adaptive event-driven techniques, both simple to ...

Time synchronization is a hot research topic for data fusion, locali‐ zation, duty cycle scheduling, and topology management. Global time synchro‐ nization is preferred to bring all sensor nodes of a wireless sensor network (WSN) on a common notion of time in the applications (surveillance and target tracking) where coordinated actuation and cooperative communication is desired for the meaningf...