127 research outputs found
Analysis of Power-aware Buffering Schemes in Wireless Sensor Networks
We study the power-aware buffering problem in battery-powered sensor
networks, focusing on the fixed-size and fixed-interval buffering schemes. The
main motivation is to address the yet poorly understood size variation-induced
effect on power-aware buffering schemes. Our theoretical analysis elucidates
the fundamental differences between the fixed-size and fixed-interval buffering
schemes in the presence of data size variation. It shows that data size
variation has detrimental effects on the power expenditure of the fixed-size
buffering in general, and reveals that the size variation induced effects can
be either mitigated by a positive skewness or promoted by a negative skewness
in size distribution. By contrast, the fixed-interval buffering scheme has an
obvious advantage of being eminently immune to the data-size variation. Hence
the fixed-interval buffering scheme is a risk-averse strategy for its
robustness in a variety of operational environments. In addition, based on the
fixed-interval buffering scheme, we establish the power consumption
relationship between child nodes and parent node in a static data collection
tree, and give an in-depth analysis of the impact of child bandwidth
distribution on parent's power consumption.
This study is of practical significance: it sheds new light on the
relationship among power consumption of buffering schemes, power parameters of
radio module and memory bank, data arrival rate and data size variation,
thereby providing well-informed guidance in determining an optimal buffer size
(interval) to maximize the operational lifespan of sensor networks
Automatic Performance Setting for Dynamic Voltage Scaling
The emphasis on processors that are both low power and high performance has resulted in the incorporation of dynamic voltage scaling into processor designs. This feature allows one to make fine granularity tradeoffs between power use and performance, provided there is a mechanism in the OS to control that tradeoff. In this paper, we describe a novel software approach to automatically controlling dynamic voltage scaling in order to optimize energy use. Our mechanism is implemented in the Linux kernel and requires no modification of user programs. Unlike previous automated approaches, our method works equally well with irregular and multiprogrammed workloads. Moreover, it has the ability to ensure that the quality of interactive performance is within user specified parameters. Our experiments show that as a result of our algorithm, processor energy savings of as much as 75% can be achieved with only a minimal impact on the user experience.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41391/1/11276_2004_Article_5091297.pd
Pancreaticogastrostomy: a pancreas-transfixing method with duct-to-mucosa anastomosis (with video)
Pancreatic fistula still remains a persistent problem after pancreaticoduodenectomy. We have devised a pancreas-transfixing suture method of pancreaticogastrostomy with duct-to-mucosa anastomosis. This technique is simple and reduces the risk of pancreatic leakage by decreasing the risk of suture injury of the pancreas and by embedding the transected stump into the wall of the stomach. This novel technique of pancreaticogastrostomy is an effective reconstructive procedure following pancreaticoduodenectomy, especially for patients with a soft and fragile pancreas
Automatic Performance-Setting for Dynamic Voltage Scaling
The emphasis on processors that are both low-power and high-performance has resulted in the incorporation of dynamic voltage scaling into processor designs. This feature allows one to make fine granularity trade-offs between power use and performance, provided there is a mechanism in the OS to control that trade-off. In this paper, we describe a novel software approach to automatically controlling dynamic voltage scaling to optimize energy use. Our mechanism is implemented in the Linux kernel and requires no modification of user programs. Unlike previous automated approaches, our method works equally well with irregular and multiprogrammed workloads. Moreover, it has the ability to ensure that the quality of interactive performance is within user specified parameters. Our experiments show that as a result of our algorithm, processor energy savings of as much as 75 % can be achieved with only a minimal impact on the user experience
Automatic Monitoring for Interactive Performance and Power Reduction
this paper is called PAST. In this policy the utilization for the most recent interval is computed and if it is above a cer- 1
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