This post was done in partnership with Wirecutter. When readers choose to buy Wirecutter's independently chosen editorial picks, Wirecutter and Engadget may earn affiliate commission. If you want to see who's on the other side of your door without having to get up and look yourself, then the Ring Video Doorbell 2 is the best choice for most everyone. It lets you screen (and record) visitors and keep an eye out for package deliveries. Motion and ring alerts to a smartphone are typically fast, audio and 1080p video are clear, and the Ring 2 can be powered by either standard doorbell wiring or a removable rechargeable battery. The Ring Video Doorbell 2 performs like a cross between a modestly aggressive guard dog and a trusty digital butler. In addition to notifying you--audibly and via smartphone--of activity, it records all motion events to the cloud, letting you view those recordings (as well as live video) on your phone or computer any time. It's also compatible with a good number of smart-home devices, platforms, and monitored security systems. Though video recording and storage require a subscription, the $30 annual fee (a mere 8¢ per day) for 60 days of unlimited video storage is downright cheap compared with the competition. We like the Ring Video Doorbell Pro for all the reasons we like the Ring 2. Additionally, it has a much slimmer and sleeker design that will fit in more doorframes and includes the option for customized motion-detection zones.

In this paper, we develop a multi-agent reinforcement learning (MARL) framework to obtain online power control policies for a large energy harvesting (EH) multiple access channel, when only the causal information about the EH process and wireless channel is available. In the proposed framework, we model the online power control problem as a discrete-time mean-field game (MFG), and leverage the deep reinforcement learning technique to learn the stationary solution of the game in a distributed fashion. We analytically show that the proposed procedure converges to the unique stationary solution of the MFG. Using the proposed framework, the power control policies are learned in a completely distributed fashion. In order to benchmark the performance of the distributed policies, we also develop a deep neural network (DNN) based centralized as well as distributed online power control schemes. Our simulation results show the efficacy of the proposed power control policies. In particular, the DNN based centralized power control policies provide a very good performance for large EH networks for which the design of optimal policies is intractable using the conventional methods such as Markov decision processes. Further, performance of both the distributed policies is close to the throughput achieved by the centralized policies. The work in this paper will appear in part at IEEE ICASSP 2019 [1] and IEEE WiOpt 2019 [2]. This research has been partly supported by the ERC-PoC 727682 CacheMire project. I. INTRODUCTION Internet-of-things (IoT) [3] networks connect a large number of low power sensors whose lifespan is typically limited by the energy that can be stored in their batteries. In this context, the advent of the energy harvesting (EH) technology [4] promises to prolong the lifespan of IoT networks by enabling the nodes to operate by harvesting energy from environmental sources, e.g., the sun, the wind, etc.

This post was done in partnership with Wirecutter. When readers choose to buy Wirecutter's independently chosen editorial picks, Wirecutter and Engadget may earn affiliate commission. Wireless TV headphones allow you to enjoy TV shows, movies, and video games without disturbing people around you. After spending dozens of hours researching the available options and testing 20 systems, we're confident that the Sennheiser RS 165 is the best one available today. It's easy to set up, sounds much better than the competition, and produces almost no latency between the audio and video (a major problem with many systems). The Sennheiser RS 165 is the best-sounding wireless TV headphone system we tested, and unlike with most of the competition, we didn't detect any noticeable delay between audio and the video we watched, making for the best experience. The lightweight headphones are comfortable to wear, easy to charge, and easy to add to most existing TVs or home theater setups. The rechargeable batteries last long enough to make it through several movies.

Robots have a tough job making their way in the world. Life throws up obstacles, and it takes a lot of computing power to avoid them. At the IEEE International Solid-State Circuits Conference last month in San Francisco, engineers presented some ideas for lightening that computational burden. That's a particularly good thing if you're a compact robot, with a small battery pack and a big job to do. Engineers at Intel are experimenting with robot-specific accelerators as part of a collaborative multirobot system.

Bassam Mohammed Abdelnabi adjusts a combustion test rig in a GE lab in Niskayuna, N.Y., on which researchers have run tests to validate simulations used to develop an AI model that they say will radically cut the time it takes to design products.Courtesy of General Electric Artificial intelligence is helping computers drive cars, recognize faces in a crowd and hold lifelike conversations. General Electric engineers now say they've used the data-intensive technology to develop tools that could cut the industrial giant's design process for jet engines and power turbines in at least half, speeding up its next generation of products. Today, it might take two days for engineers to run a computational analysis of the fluid dynamics of a single design for a turbine blade or an engine component. Scientists at General Electric's research center in Niskayuna, New York, say they've leveraged machine learning to train a surrogate model so that it can evaluate a million variations of a design in just 15 minutes. "This is, we think, a huge breakthrough," Robert Zacharias, technology director of thermosciences at GE Research, tells Forbes.

Artificial intelligence is helping computers drive cars, recognize faces in a crowd, and hold life-like conversations. General Electric engineers now say they've used the data-intensive technology to develop tools that could cut the industrial giant's design process for jet engines and power turbines in at least half, speeding up its next generation of products. Today, it might take two days for engineers to run a computational analysis of the fluid dynamics of a single design for a turbine blade or an engine component. Scientists at General Electric's research center in Niskayuna, New York, say they've leveraged machine learning to train a surrogate model so that it can evaluate a million different variations of a design in just 15 minutes. "This is, we think, a huge breakthrough," says Robert Zacharias, technology director of thermosciences at GE Research.

Apple will finally fix your iPhone, even if it has someone else's battery inside. Until now, iPhones with replacement battery that were installed by someone other than Apple employees have been excluded from being fixed. They were ineligible to be looked at by the Genius Bar, for instance, meaning that getting a battery replacement could mean passing up the chance for any other service work. That was the case even if the problem was with another component and not the battery, meaning that the entire phone would be banned from repairs just for having a third-party battery. We'll tell you what's true.

When I reviewed First Alert's Onelink Safe & Sound smoke alarm in mid-2018, I found it to be a powerful entry in the smart smoke detector market. Its inclusion of Bluetooth and an Amazon Echo-compatible smart speaker set it apart from every smoke and carbon-monoxide detector on the market. But its $199 price tag also made it far and away the most expensive device of its type on the market--and that price hasn't budged since its release. Enter the Onelink Smoke Carbon Monoxide Alarm, which lowers the cost of the original product by stripping out its most compelling features: The smart speaker and Bluetooth. Like other products in this category, the Onelink Smoke Carbon Monoxide Alarm is designed to extend the capabilities of a smoke detector by linking it with your smartphone. It still functions by firing off a (rather loud) local siren whenever smoke or CO are detected, but it also (supposedly) sends push alerts to your mobile device, a feature that is most helpful for times when you aren't at home but still want the peace of mind that it's not on fire.

This is not a story about how the polar vortex is bad--bad for the human body, bad for public transportation, bad for virtually everything in its path. This is a story about how one being among us is actually taking advantage of the historic cold snap: Cassie the bipedal robot. While humans suffer through the chill, this trunkless pair of ostrich-like legs is braving the frozen grounds of the University of Michigan, for the good of science. "When we saw the announcement for the polar vortex, we started making plans to see how long we could operate in that kind of weather," says roboticist Jessy Grizzle. "We were going to tie a scarf on her just so it looked cute, but we decided people would think that was keeping her warm and affecting the experiment, so we didn't." Scarves aside, this is vital research for a future in which robots tackle not just polar vortices but any number of other brutal environments.

Amazon is selling a robotic toilet cleaner for $499.99 (£400) that will keep the lavatory squeaky clean for you. The droid is called Giddel and is designed to scrub the rim and bowl of a toilet so customers don't have to complete the arduous chore. It weighs more than six pounds (3kg) and is powered by a rechargeable lithium-ion battery. The hefty price tag includes the robot, cleaning accessories and an elongated toilet seat to allow the robot to clip on. Amazon is selling a robotic toilet cleaner called Giddel (pictured) for $499.99 (£400) that will keep the lavatory squeaky clean The droid is designed to scrub the rim and bowl of a toilet so customers don't have to complete the arduous chore It weighs 1.5 pounds (3kg) and is powered by a rechargeable lithium-ion battery.