An amphibious supercar design that would allow its mega rich owners to look stylish and beat city traffic by travelling through water at high speed has been unveiled. According to its creators, the electric powered Amphi-X would reach speeds of more than 260 mph (418 km/h) on land and an average speed of over 90 mph (145 km/h) in water, the same as a modern speed boat. The car has been designed for the world's super rich to avoid congested roads of big cities, but comes with a hefty £2.5 million price tag. An amphibious supercar design that would allow its mega rich owners to look stylish and beat city traffic by travelling through water at high speed has been unveiled. The car has been designed for the world's super rich to avoid congested roads of big cities, but comes with a hefty £2.5 million price tag.

Vava has unveiled a new pet camera that will let you follow your dog or cat around the house when you're not home. The device, said to be the first mobile pet cam in the world, made its debut at CES in Las Vegas this week. Vava's Pet Cam is equipped with two-way audio so you can hear and speak to your pet remotely, and collision detection will let it roam the house without bumping into anything or falling down the stairs. Vava has unveiled a new pet camera that will let you follow your dog or cat around the house when you're not home. The Vava Pet Cam connects with an app that lets you interact with your pets from afar.

LAS VEGAS--Get ready to peek at a new Ring. For homes and apartments that don't have doorbells, the folks behind the Ring video doorbell have a new offering, the Ring Door View Cam. The company describes it as "a wire-free video doorbell that transforms a door viewer into a smart security device." Jamie Siminoff, the founder of Ring, says the peep hole cam has been one of the top requests from customers. "There's a small subset of people who don't have room for a door bell," he says.

The reduced-price replacements last until the end of the year, at which point the cost will dramatically increase. For the moment, a new battery costs only £25 – but once the new year arrives, that will rocket up to as much as £65. Old batteries can cause significant problems for their owners as iPhones age. With use, the power begins to drop – something that can lead to phones lasting for much less time, and to Apple having to slow down phones to ensure that they don't crash because they're not getting enough power. It was the revelation that Apple was doing that – throttling performance on older phones, in line with more spectacular rumours that swirled before it was admitted – that led to the cheap repairs in the first place.

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 commissions. Read Wirecutter's continuously updated list of Black Friday deals here. This drops the Series 3 38mm, and the 42mm ($230) to the best prices we've seen to date, almost $60 below recent sales. The Apple Watch Series 3 is the budget pick in our guide to Apple Watches. Nick Guy and Dan Frakes write, "It was introduced in 2017, but it offers most of the features and experience of the Series 4 at a significantly lower price. The Series 3 models have smaller screens--the biggest obvious difference--aren't as speedy, don't do automatic workout detection, and won't support the Series 4's ECG feature or fall detection. Even so, the Series 3 is still fast, designed with the same GPS features and swim-friendly waterproofing, and equipped with a bright screen that's easy to see outside."

In this paper, we introduce proximal gradient temporal difference learning, which provides a principled way of designing and analyzing true stochastic gradient temporal difference learning algorithms. We show how gradient TD (GTD) reinforcement learning methods can be formally derived, not by starting from their original objective functions, as previously attempted, but rather from a primal-dual saddle-point objective function. We also conduct a saddle-point error analysis to obtain finite-sample bounds on their performance. Previous analyses of this class of algorithms use stochastic approximation techniques to prove asymptotic convergence, and do not provide any finite-sample analysis. We also propose an accelerated algorithm, called GTD2-MP, that uses proximal "mirror maps" to yield an improved convergence rate. The results of our theoretical analysis imply that the GTD family of algorithms are comparable and may indeed be preferred over existing least squares TD methods for off-policy learning, due to their linear complexity. We provide experimental results showing the improved performance of our accelerated gradient TD methods.

Scientists have found a way to boost the battery life of your smartphone or tablet by several hours. They claim that shifting reams of data from your favourite apps to cloud storage services could cut the power they burn through by up to 60 per cent. Tools would identify the most power-hungry parts of a mobile app and then move them to the cloud using a technique called code-offloading. For an average smartphone with an average battery capacity, applying the technology to every app could extend the battery life by up to six hours in a'best-case scenario', researchers said. The technology could be used to build the next generation of disaster relief or search and rescue robots, where battery life is critical.

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. Although flying a drone might sound like the biggest risk in operating one, dealing with the batteries is potentially more explosive. At the 100 hospital emergency rooms that report electronics-related injury cases to the US Consumer Product Safety Commission, more than 200 incidents (PDF) involving drone batteries, stemming from fire, smoke, and explosions, were recorded between 2012 and 2017. Not every drone-battery incident results in an injury, but each pilot and expert I interviewed had a story about an exploding or fiery lithium battery going off especially after it had repeatedly crashed to the ground inside a drone.

"Ladies and gentlemen, I'll be very glad to tell my story. I am a smart fellow as I have a very fine brain of 48 electrical relays." This is how Elektro the robot introduced itself to crowds at the 1939 New York World's Fair. Standing 2.1 meters tall and weighing 118 kilograms, Elektro performed 26 different tricks, including walking, talking, counting, and singing. It had a vocabulary of approximately 700 words, although its responses were all prerecorded and played back from 33⅓-rpm records.

Ambient backscatter has been introduced with a wide range of applications for low power wireless communications. In this article, we propose an optimal and low-complexity dynamic spectrum access framework for RFpowered ambient backscatter system. Under the dynamics of the ambient signals, we first adopt the Markov decision process (MDP) framework to obtain the optimal policy for the secondary transmitter, aiming to maximize the system throughput. However, the MDP-based optimization requires complete knowledge of environment parameters, e.g., the probability of a channel to be idle and the probability of a successful packet transmission, that may not be practical to obtain. To cope with such incomplete knowledge of the environment, we develop a low-complexity online reinforcement learning algorithm that allows the secondary transmitter to "learn" from its decisions and then attain the optimal policy. Simulation results show that the proposed learning algorithm not only efficiently deals with the dynamics of the environment, but also improves the average throughput up to 50% and reduces the blocking probability and delay up to 80% compared with conventional methods. Dynamic spectrum access (DSA) has been considered as a promising solution to improve the utilization of radio spectrum [2]. As DSA standard frameworks, the Federal Communications Commission and the European Telecommunications Standardization Institute have recently proposed Spectrum Access Systems (SAS) and Licensed Shared Access (LSA) respectively [3]. In both SAS and LSA, spectrum users are prioritized at different levels/tiers (e.g., there are three types of users with a decreasing order of priority: Incumbent Users (IUs), Priority Access Licensees (PALs), and General Authorized Access (GAAs)). Without loss of generality, in this work, we refer users with higher priority as IUs and users with lower priority as secondary users (SUs). DSA harvests under-utilized spectrum chunks by allowing an SU to dynamically access (temporarily) idle spectrum bands/whitespaces to transmit data.