Degree Of Energy Balance Research Articles

Perspective: Is the Response of Human Energy Expenditure to Increased Physical Activity Additive or Constrained?

The idea that increasing physical activity directly adds to TEE in humans (additive model) has been challenged by the energy constrained hypothesis (constrained model). This model proposes that increased physical activity decreases other components of metabolism to constrain TEE. There is a logical evolutionary argument for trade-offs in metabolism, but, to date, evidence supporting constraint is subject to several limitations, including cross-sectional and correlational studies with potential methodological issues from extreme differences in body size/composition and lifestyle, potential statistical issues such as regression dilution and spurious correlations, and conclusions drawn from deductive inference rather than direct observation of compensation. Addressing these limitations in future studies, ideally, randomized controlled trials should improve the accuracy of models of human energy expenditure. The available evidence indicates that in many scenarios, the effect of increasing physical activity on TEE will be mostly additive although some energy appears to "go missing" and is currently unaccounted for. The degree of energy balance could moderate this effect even further.

SRA: A Sensing Radius Adaptation Mechanism for Maximizing Network Lifetime in WSNs

Coverage is an important issue that has been widely discussed in wireless sensor networks (WSNs). However, it is still a big challenge to achieve both purposes of full coverage and energy balance. This paper considers the area coverage problem for a WSN in which each sensor has a variable sensing radius. To prolong the network lifetime, a weighted Voronoi diagram (WVD) is proposed as a tool for determining the responsible sensing region of each sensor according to the remaining energy in a distributed manner. The proposed mechanism, which is called sensing radius adaptation (SRA), mainly consists of three phases. In the first phase, each sensor and its neighboring nodes cooperatively construct the WVD to identify the responsible monitoring area. In the second phase, each sensor adjusts its sensing radius to reduce the overlapping sensing region such that the purpose of energy conservation can be achieved. In the last phase, the sensor with the least remaining energy further adjusts its sensing radius with its neighbor for to maximize the network lifetime. Performance evaluation and analysis reveal that the proposed SRA mechanism outperforms the existing studies in terms of the network lifetime and the degree of energy balance.