Natural flyers use soft wings to seamlessly enable a wide range of flight behaviours, including agile manoeuvres, squeezing through narrow passageways, and withstanding collisions. In contrast, conventional quadrotor designs rely on rigid frames that support agile flight but inherently limit collision resilience and squeezability, thereby constraining flight capabilities in cluttered environments. Inspired by the anisotropic stiffness and distributed mass-energy structures observed in biological organisms, we introduce FlexiQuad, a soft-frame quadrotor design approach that limits this trade-off. We demonstrate a 405-gram FlexiQuad prototype, three orders of magnitude more compliant than conventional quadrotors, yet capable of acrobatic manoeuvres with peak speeds above 80 km/h and linear and angular accelerations exceeding 3 g and 300 rad/s$^2$, respectively. Analysis demonstrates it can replicate accelerations of rigid counterparts up to a thrust-to-weight ratio of 8. Simultaneously, FlexiQuad exhibits fourfold higher collision resilience, surviving frontal impacts at 5 m/s without damage and reducing destabilising forces in glancing collisions by a factor of 39. Its frame can fully compress, enabling flight through gaps as narrow as 70% of its nominal width. Our analysis identifies an optimal structural softness range, from 0.006 to 0.77 N/mm, comparable to that of natural flyers' wings, whereby agility, squeezability, and collision resilience are jointly achieved for FlexiQuad models from 20 to 3000 grams. FlexiQuad expands hovering drone capabilities in complex environments, enabling robust physical interactions without compromising flight performance.

The emergence of truck-drone collaborative systems in last-mile logistics has positioned the Traveling Salesman Problem with Drones (TSP-D) as a pivotal extension of classical routing optimization, where synchronized vehicle coordination promises substantial operational efficiency and reduced environmental impact, yet introduces NP-hard combinatorial complexity beyond the reach of conventional optimization paradigms. Deep reinforcement learning offers a theoretically grounded framework to address TSP-D's inherent challenges through self-supervised policy learning and adaptive decision-making. This study proposes a hierarchical Actor-Critic deep reinforcement learning framework for solving the TSP-D problem. The architecture consists of two primary components: a Transformer-inspired encoder and an efficient Minimal Gated Unit decoder. The encoder incorporates a novel, optimized k-nearest neighbors sparse attention mechanism specifically for focusing on relevant spatial relationships, further enhanced by the integration of global node features. The Minimal Gated Unit decoder processes these encoded representations to efficiently generate solution sequences. The entire framework operates within an asynchronous advantage actor-critic paradigm. Experimental results show that, on benchmark TSP-D instances of various scales (N=10 to 100), the proposed model can obtain competitive or even superior solutions in shorter average computation times compared to high-performance heuristic algorithms and existing reinforcement learning methods. Moreover, compared to advanced reinforcement learning algorithm benchmarks, the proposed framework significantly reduces the total training time required while achieving superior final performance, highlighting its notable advantage in training efficiency.

Is Trump losing patience with Putin? Will sanctions against Russian oil giants hurt Putin? Ukraine has hit back at Russia's attempts to disable its energy infrastructure with air strikes that succeeded in disrupting power and heating in two cities across the border. Alexander Gusev, regional governor of Voronezh, said several drones were electronically jammed over the city - home to more than one million people - and sparked a fire at a local utility facility that was quickly extinguished. A Russian Defence Ministry statement made no mention of either the Voronezh or Belgorod areas, reporting 44 Ukrainian drones were destroyed or intercepted by Russian forces during the night.

Is Trump losing patience with Putin? Will sanctions against Russian oil giants hurt Putin? The United Kingdom is sending military equipment and personnel to Belgium after a spate of disruptive drone sightings forced the temporary closures of two major airports. Air Chief Marshal Richard Knighton told the BBC network on Sunday that the military had agreed to "deploy our people, our equipment to Belgium to help them" after a request from Belgian authorities. In the past week, both Belgium's main international airport at Brussels and one of Europe's biggest cargo airports at Liege were forced to close temporarily because of drone incursions.

UK military personnel and equipment are being sent to Belgium to help it bolster its defences after drone incursions on its airspace, suspected of being carried out by Russia. The new head of the UK military, Sir Richard Knighton, told the BBC's Sunday with Laura Kuenssberg that his Belgian counterpart asked for assistance earlier this week and that kit and personnel were on the way. Belgium's main airport Zavantem was forced to close temporarily on Thursday night after drones were spotted nearby . They were also spotted in other locations, including a military base. Sir Richard said it was not known if the incursions were by Russia, but added it was plausible they had been ordered by Moscow.

At least six people have died after Russia launched hundreds of missile and drone attacks on energy infrastructure and residential targets in Ukraine overnight. A strike on an apartment building in the city of Dnipro killed two people and wounded 12, while three died in Zaporizhzhia. In all, 25 locations across Ukraine, including the capital city Kyiv, were hit, leaving many areas without electricity and heating. Prime Minister Yulia Svyrydenko said on Telegram that major energy facilities were damaged in the Poltava, Kharkiv and Kyiv regions, and work was under way to restore power. In Russia, the defence ministry said its forces had shot down 79 Ukrainian drones overnight. The Ukrainian air force said Russia had launched more than 450 exploding bomber drones and 45 missiles.

Is Trump losing patience with Putin? Will sanctions against Russian oil giants hurt Putin? At least 10 people have been killed, and more parts of Ukraine have been plunged into darkness, after another night of intense Russian attacks across the country, local authorities said, as diplomatic momentum to end the nearly four-year war falters. Ukraine's military announced on Saturday morning that hundreds of Russian drones, as well as missiles launched from the air, ground and sea, targeted critical infrastructure, a frequent Kremlin target as another harsh winter of war looms. Most of the missiles went through defences, with only nine successfully shot down, but 406 of the drones were intercepted.

The Belgian government has told the BBC it is urgently trying to acquire drone defences after a sighting forced its main airport near Brussels to close temporarily. Flights were paused at Zaventem airport on Thursday night, after drones were spotted nearby. They were also seen in other locations, including a military base. At first, drones flying over our military bases were seen as our problem, Defence Minister Theo Francken said. Now it has become a serious threat affecting civilian infrastructure across multiple European countries.

Loud explosions have been heard in Sudan's army-held capital Khartoum, shortly after the paramilitary Rapid Support Forces (RSF) said it was ready for a truce after fighting the government-aligned Sudanese Armed Forces (SAF) for more than two years of brutal civil war. The attacks took place early Friday, targeting Omdruman, part of the greater Khartoum area, and army-held Atbara to the north of the capital, and were intercepted by the army's air defence systems, according to Al Jazeera's Hiba Morgan. SAF has yet to give an official response to the proposal, which would see a three-month humanitarian pause followed by a permanent ceasefire that would ostensibly pave the way for an eventual political transition to civilian rule. A Sudanese military official told the news agency The Associated Press on Thursday that the army welcomed the proposal, but would only agree to a truce when the RSF completely withdraws from civilian areas and gives up weapons. Reporting from Khartoum, Al Jazeera's Morgan said that it seemed the army would continue fighting until the RSF met its conditions.

Explosions have been heard near the Sudanese capital of Khartoum, a day after the paramilitary Rapid Support Forces (RSF) said it would agree to a humanitarian ceasefire. Residents in Khartoum, which is controlled by the army, told the AFP news agency that they were woken overnight by the sound of drones and explosions. The blasts appeared to take place near a military base and a power station in the early hours of Friday morning, the residents said. The RSF has not addressed these accounts, but Sudan's military-led government said it would be wary of agreeing to a truce as the group did not respect ceasefires. The two sides have been embroiled in a civil war that has killed at least 150,000 people and forced 12 million others from their homes since it erupted in April 2023.