Search results for "Wake"

MAC Protocols for Wake-up Radio: Principles, Modeling and Performance Analysis

2018

[EN] In wake-up radio (WuR) enabled wireless sensor networks (WSNs), a node triggers a data communication at any time instant by sending a wake-up call (WuC) in an on-demand manner. Such wake-up operations eliminate idle listening and overhearing burden for energy consumption in duty-cycled WSNs. Although WuR exhibits its superiority for light traffic, it is inefficient to handle high traffic load in a network. This paper makes an effort towards improving the performance of WuR under diverse load conditions with a twofold contribution. We first propose three protocols that support variable traffic loads by enabling respectively clear channel assessment (CCA), backoff plus CCA, and adaptive …

Does Wake-Up Radio Always Consume Lower Energy Than Duty-Cycled Protocols?

2017

Many recent studies anticipate that wake-up radio (WuR) will replace traditional duty-cycled (DC) protocols given its overwhelming performance superiority on energy consumption. Meanwhile, the question on whether WuR performs always better than DC protocols has not been answered explicitly. In this paper, we investigate in-depth the energy consumption performance of WuR by considering various levels of traffic load in a wireless sensor network. By comparing SCM-WuR with both synchronous MAC (S-MAC) and asynchronous MAC (X-MAC), we ascertain that SCM-WuR does consume orders of magnitude lowerenergythanDCprotocolswhentrafficloadislow.Howe ver, our numerical results reveal at the same time that …

A degraded state of consciousness in healthy awake humans?

2021

Brain and Breathing

2014

Breathing is an essential feature of living organisms, and control of breathing is a very complex topic in human physiology. Breathing is differently modulated under conditions of wakefulness and sleep, and ventilation decreases during sleep in normal subjects. In patients with respiratory diseases, sleep represents a very vulnerable condition, since gas exchange usually worsens, especially in REM sleep. Several types of respiratory events can occur during sleep, and knowledge of control of breathing is essential to understand their pathophysiology. This chapter summarizes the main characteristics of ventilation during both wakefulness and sleep, the differences found between genders, and t…

Long-lived contrails and convective cirrus above the tropical tropopause

2017

Abstract. This study has two objectives: (1) it characterizes contrails at very low temperatures and (2) it discusses convective cirrus in which the contrails occurred. (1) Long-lived contrails and cirrus from overshooting convection are investigated above the tropical tropopause at low temperatures down to −88 °C from measurements with the Russian high-altitude research aircraft M-55 Geophysica, as well as related observations during the SCOUT-O3 field experiment near Darwin, Australia, in 2005. A contrail was observed to persist below ice saturation at low temperatures and low turbulence in the stratosphere for nearly 1 h. The contrail occurred downwind of the decaying convective system H…

Morning and evening type: The cortisol awakening response in a sleep laboratory.

2019

Abstract Background Earlier evidence indicated an association between chronotype and the cortisol awakening response (CAR). However, these earlier data were collected without objective control for participant compliance being available, which, following recent guidelines, is considered critical for ensuring data validity. Here, we are seeking to replicate these earlier findings within a well-controlled sleep laboratory set up. Methods The sample consisted of 103 young males, including 12 participants defined as ‘evening’ (MEQ   59) types. All participants slept for one night in a sleep laboratory and were wakened at 6:30 AM the next morning. Saliva samples for the assessment of the CAR were…

Achieving Ultra Energy-efficient and Collision-free Data Collection in Wake-up Radio Enabled mIoT

2020

Forces and flow structures evolution on a car body in a sudden crosswind

2014

A vehicle driver is commonly exposed to strong side air flows, for example when passing through a wind gust. The aerodynamic efforts generated in these situations may induce undesired lateral deviations, which can lead to dramatic effects, if the driver is surprised. In order to simulate a sudden yaw angle change on a moving vehicle, a double wind tunnel facility, adapted from the one of Ryan, Dominy, 2000. Wake Surveys Behind a Passenger Car Subjected to a Transient Cross-wind Gust. SAE Technical Paper No. 2000-01-0874 is developed. Two Windsor car body models, differing from their rear geometry, are analysed. The transient evolution of the side force and yaw moment aerodynamic coefficient…

Turbulences of the supersonic gas flow during cold spraying and their negative effects: A DNS CFD analysis coupled with experimental observation and …

2020

Abstract This paper investigates the phenomenological flow during cold spraying through DNS CFD analysis and experimental observations. The transient DNS computation shows that the gas flow begins to be instable inside the nozzle and generates self-sustained intermittent swirls across the nozzle exit due the shearing behavior of the flow. There is alternate swirling within the separated sheared layers on top and then on bottom of the jet, at sporadic time intervals. The swirls are not strictly periodic in nature, but they recur with an irregular frequency. The temperature field exhibits analogous variation and the thermal turbulence produces a heating confinement within the end zone of the …

Dynamic mode decomposition of magnetohydrodynamic bubble chain flow in a rectangular vessel

2021

We demonstrate the first application of dynamic mode decomposition (DMD) to bubble flow with resolved dynamic liquid/gas boundaries. Specifically, we have applied DMD to the output of numerical simulations for a system where chains of bubbles ascend through a rectangular liquid metal vessel. Flow patterns have been investigated in the vessel and bubble reference frames. We show how gas flow rate and applied magnetic affect bubble wake flow and larger-scale flow structures within the liquid metal vessel by examining the velocity field mode statistics over trajectory time and total flow time as well as the computed mode velocity fields. The results of this proof-of-concept study indicate that…