SAN FRANCISCO Cheap Nike Air Max 2018 Clearance , July 19 (Xinhua) -- Two researchers at Oregon State University have built a framework for autonomous underwater vehicles, or AUVs, to plan energy-efficient trajectories through disturbances that are strong and uncertain, like ocean currents and wind fields.
AUVs such as underwater gliders are valuable research tools limited primarily by their energy budget, meaning every bit of battery power wasted via inefficient trajectories cuts into the time they can spend working. And greater energy efficiency means the AUVs can gather data longer and better.
"Historically Cheap Nike Air Max Clearance , a lot of oceanography data sets and sampling came from using ships, which are expensive and can only really be out for a few days at a time," noted Dylan Jones, a Ph.D. student in OSU's robotics program and lead author on the study published in IEEE Robotics and Automation Letters. "With autonomous underwater vehicles, you can get months-long monitoring. And a way to extend those vehicles' missions is through smarter planning for how they get from one point of interest to another."
Built by Jones and Ph.D. advisor Geoff Hollinger Cheap Air Max 1 Clearance , assistant professor of mechanical engineering in OSU's College of Engineering, the framework involves an algorithm that samples alternate paths, and comparison metrics that let a vehicle decide when it makes sense to switch paths based on new information collected about environmental disturbances.
They tested the framework in a simulated environment, namely a data set of currents from the Regional Ocean Modeling System, and also on a windy lake with an autonomous boat. The results show that the algorithm can plan vehicle paths that are more energy efficient than ones planned by existing methods Cheap Air Max 2017 Clearance , that it is robust enough to deal with environments for which not much data is available, and that three of the framework's five path comparison metrics can be used to plan more efficient routes compared to planning based solely on the ocean current forecast.
"These are under-actuated vehicles - they don't go fast in relation to the strong ocean currents, so one way to get them to travel more efficiently is to go with the flow, to coast and not use energy," Jones said Cheap Air Max 2018 Clearance , noting that overcoming strong disturbances is a critical component of putting any kind of robot in a real-life environment, and past planning algorithms haven't always considered the dynamics of the vehicle they were planning for.
"We're building more intelligence into these vehicles so they can more reliably accomplish their missions," he was quoted as saying in a news release from OSU in the U.S. Pacific Northwest on Wednesday.
Future research will also deal with "informative path planning," namely gathering information about the environment and disturbances that the algorithm can use later to plan energy-efficient routes. "How do we combine these two ideas - planning a path for energy efficiency while also trying to gather information that will inform efficient path planning?" Jones said. "There will be tradeoffs and it might come down to, do I pay five hours now to save six hours later on?"
SEOUL Cheap Air Max Clearance , Dec. 30 (Xinhua) -- Two sailors were confirmed dead, with four missing, in a South Korean fishing boat fire accident that occurred on Tuesday morning, local media reported.
The Munseong 103 caught fire in waters about five nautical miles northeast of South Korea's easternmost islets of Dokdo, called Takeshima in Japan Cheap Nike Air Max 1 Shoes , at about 5:13 a.m. local time (2013 GMT) , Yonhap News Agency reported citing the Ministry of Public Safety and Security.
Aboard the 29-ton vessel were eight South Koreans and two Vietnamese.
Six were rescued from the ship, but two of them died later. Two South Koreans and two Vietnamese went missing.
Search operations are still under way. A rescue ship was sent to the site, and six naval vessels and four airplanes were dispatched to help search the fishermen.
The Munseong 103, which departed from the country's southern resort island of Jeju on Nov. 16 Cheap Nike Air Max 2017 Shoes , was en route to Hupo, the country's southeastern city while catching blowfish.
The blaze is estimated to have started from the engine room, but the exact cause is still under investigation.
WASHINGTON, Feb. 21 (Xinhua) -- A pair of U.S. astronauts successfully completed the first of three spacewalks on Saturday, installing over 100 meters of cable outside the International Space Station as part of a preparation for future arrivals of American commercial crew spacecraft.
NASA astronauts Barry Wilmore and Terry Virts "completed all the scheduled tasks for today and one get ahead task Cheap Nike Air Max 2018 Shoes ," the U.S. space agency said in a statement. "They rigged a series of power and data cables at the forward end of the Harmony module and Pressurized Mating Adapter-2 and routed 340 of 360 feet (110 meters) of cable."
The cable routing work is part of a reconfiguration of station systems and modules for the installation of two international docking adapters to be delivered by a pair of SpaceX Dragon cargo spacecraft later this year.
The new docking ports will welcome U.S. commercial spacecraft launching from Florida beginning in 2017, permitting the standard station crew size to grow from six to seven and potentially double the amount of crew time devoted to research from 40 hours to 80 hours per week, NASA said.
The two astronauts ventured out of the station at 7:45 a.m. EDT (1245 GMT) and reentered the orbiting outpost at 2:26 p.m. EST ( 1926 GMT).
The spacewalk was the first for Virts, and the second for Wilmore, who has conducted one spacewalk last October.
The duo will perform two more spacewalks on Wednesday and March 1.
Because the spacewalks focused on laying and attaching cables Cheap Nike Air Max Shoes , NASA's space station blog called the two astronauts "cable guys."
NASA has relied on Russia's Soyuz capsules to deliver astronauts to the station sinc.
