Engineering
Dali forcefully collided with Key Bridge, with a force equivalent to that of 66 heavy trucks traveling at high speeds on a highway
The cargo ship Dali caused significant damage to the Francis Scott Key Bridge when it collided with one of the bridge piers. As a result, three main truss spans, which were constructed using connected steel elements forming triangles, were knocked down. This incident occurred early on Tuesday morning, March 26, 2024.
The bridge collapse occurred with such suddenness that it afforded the work crews on the bridge little opportunity to evacuate. As a civil engineer, I have been closely monitoring this disaster, as it presents an opportunity to explore methods for enhancing the resilience of infrastructure, such as large bridges. For a bridge of this magnitude to fail, a significant impact force would be necessary. By applying the fundamental principles of physics, we can make a rough estimation of the force involved.
The impulse momentum theorem
Calculating the magnitude of the collision force of Dali can be done using the impulse momentum theorem, a fundamental principle in physics.
The theorem is derived from Newton’s second law, which states that force equals mass times acceleration. Adding time to both sides of the equation, the impulse momentum theorem reveals that force multiplied by time is equal to mass multiplied by the change of velocity when the force is applied.
The equation F*∆t = m*∆v represents a fundamental relationship in physics.
When calculating the impulse momentum theory for Dali’s collision, you’ll need to multiply the collision force by the duration of the collision. Then, compare that to Dali’s mass times the difference in velocity between before and after the crash. The mass of Dali, the length of the collision, and the amount of deceleration that occurs after the crash all affect its collision force.
The data regarding Dali’s accident
When fully loaded, Dali weighs a staggering 257,612,358 pounds or 116,851 metric tonnes. The vehicle was moving at a velocity of 10 miles per hour, equivalent to 16.1 kilometers per hour, prior to the impact. Following the collision with the bridge pier, Dali decelerated to 7.8 miles per hour, or 12.6 kilometers per hour.
Another crucial factor to consider is the collision time, which denotes the duration of the ship’s impact with the bridge during the crash, resulting in a sudden deceleration for Dali.
Based on the data from Dali’s voyage data recorder and the Maryland Transportation Authority Police log, it has been determined that the collision time was less than four seconds, although the exact time is still unknown.
When cars collide on a highway, the duration of the collision is typically between half a second and one second. It is logical to estimate the collision force by using the collision time duration, as Dali’s crash bears resemblance to a vehicle crashing on a bridge pier.
The powerful impact of Dali’s collision
By utilizing those estimates and applying the impulse momentum theory, one can gain a solid understanding of the likely magnitude of Dali’s collision force.
The collision force is determined by multiplying the mass of the object by the change in velocity before and after the crash and then dividing that by the duration of the collision. If we assume a collision time of just one second, the resulting collision force amounts to a staggering 26,422,562 pounds.
Calculating the equation, the result is 26,422,562 pounds
As a biophysicist would know, the American Association of State Highway and Transportation Officials has provided valuable information regarding the collision force on a highway bridge pier resulting from a truck crash, which is estimated to be around 400,000 pounds.
That being said, the impact of the cargo ship Dali on the Baltimore Key Bridge pier is comparable to the combined force of 66 heavy trucks traveling at a speed of 60 miles per hour (97 km per hour) and colliding with the bridge pier simultaneously. This level of magnitude exceeds the force that the pier is capable of withstanding.
Creating a bridge that can withstand such a high level of collision force would be technically feasible, but it would significantly raise the cost of the project. Engineers are exploring various methods to decrease the impact on the piers, such as implementing protective barriers that can absorb and dissipate energy. Implementing these types of solutions has the potential to avert future disasters.Engaging in a dialogue
Amanda Bao is an Associate Professor of Civil Engineering Technology, Environmental Management, and Safety at the Rochester Institute of Technology.
This article has been republished from The Conversation under a Creative Commons license. Check out the original article.
Artificial Intelligence
Google DeepMind Shows Off A Robot That Plays Table Tennis At A Fun “Solidly Amateur” Level
Have you ever wanted to play table tennis but didn’t have anyone to play with? We have a big scientific discovery for you! Google DeepMind just showed off a robot that could give you a run for your money in a game. But don’t think you’d be beaten badly—the engineers say their robot plays at a “solidly amateur” level.
From scary faces to robo-snails that work together to Atlas, who is now retired and happy, it seems like we’re always just one step away from another amazing robotics achievement. But people can still do a lot of things that robots haven’t come close to.
In terms of speed and performance in physical tasks, engineers are still trying to make machines that can be like humans. With the creation of their table-tennis-playing robot, a team at DeepMind has taken a step toward that goal.
What the team says in their new preprint, which hasn’t been published yet in a peer-reviewed journal, is that competitive matches are often incredibly dynamic, with complicated movements, quick eye-hand coordination, and high-level strategies that change based on the opponent’s strengths and weaknesses. Pure strategy games like chess, which robots are already good at (though with… mixed results), don’t have these features. Games like table tennis do.
People who play games spend years practicing to get better. The DeepMind team wanted to make a robot that could really compete with a human opponent and make the game fun for both of them. They say that their robot is the first to reach these goals.
They came up with a library of “low-level skills” and a “high-level controller” that picks the best skill for each situation. As the team explained in their announcement of their new idea, the skill library has a number of different table tennis techniques, such as forehand and backhand serves. The controller uses descriptions of these skills along with information about how the game is going and its opponent’s skill level to choose the best skill that it can physically do.
The robot began with some information about people. It was then taught through simulations that helped it learn new skills through reinforcement learning. It continued to learn and change by playing against people. Watch the video below to see for yourself what happened.
“It’s really cool to see the robot play against players of all skill levels and styles.” Our goal was for the robot to be at an intermediate level when we started. “It really did that, all of our hard work paid off,” said Barney J. Reed, a professional table tennis coach who helped with the project. “I think the robot was even better than I thought it would be.”
The team held competitions where the robot competed against 29 people whose skills ranged from beginner to advanced+. The matches were played according to normal rules, with one important exception: the robot could not physically serve the ball.
The robot won every game it played against beginners, but it lost every game it played against advanced and advanced+ players. It won 55% of the time against opponents at an intermediate level, which led the team to believe it had reached an intermediate level of human skill.
The important thing is that all of the opponents, no matter how good they were, thought the matches were “fun” and “engaging.” They even had fun taking advantage of the robot’s flaws. The more skilled players thought that this kind of system could be better than a ball thrower as a way to train.
There probably won’t be a robot team in the Olympics any time soon, but it could be used as a training tool. Who knows what will happen in the future?
The preprint has been put on arXiv.
Engineering
New concrete that doesn’t need cement could cut carbon emissions in the construction industry
Even though concrete is a very common building material, it is not at all the most environmentally friendly choice. Because of this, scientists and engineers have been looking for alternatives that are better for the environment. They may have found one: concrete that doesn’t need cement.
Cement production, which is a crucial ingredient in concrete, ranks as the third most significant contributor to human-caused carbon emissions globally. Nevertheless, in recent years, a multitude of alternative techniques for producing more environmentally friendly concrete have surfaced. One proposed method involves utilizing industrial waste and steel slag as CO2-reducing additives in the concrete mixture. Another suggestion is to utilize spent coffee grounds to enhance the strength of the concrete while reducing the amount of sand required.
However, a certain company has devised a technique to produce cement-free concrete suitable for commercial enterprises.
The concrete has the potential to have a net reduction in carbon dioxide and has the ability to prevent approximately 1 metric ton of carbon emissions for every metric ton used. If this statement is accurate, the cement-free binder will serve as a noteworthy substitute for Portland cement. According to BGR, the new concrete also complies with all the industry standards of traditional cement concrete, ensuring that there is no compromise in terms of strength and durability.
While it is still in the early stages, the situation seems encouraging. C-Crete Technologies, a company specializing in materials science and holding the patents for a novel form of concrete, has utilized approximately 140 tons of this new cast-in-place (pourable) concrete in recent construction endeavors.
In September 2023, the company was granted an initial sum of almost $1 million, promptly succeeded by an additional $2 million, by the US Department of Energy to advance the progress of its technology. In addition, it has garnered numerous accolades that are facilitating its growth in operations.
The widespread adoption of cement-free concrete in future construction projects has the potential to significantly alter the environmental impact of the industry. Although C-Crete seems to be one of the few companies currently exploring these new alternatives on a large scale, it is likely that others will also start embracing them in the near future.
Engineering
To get gold back from electronic waste, the Royal Mint of the UK is using a new method
There are hidden mountains of gold in the junkyards, full of old smartphones, computers that don’t work anymore, and broken laptops. A new project in the UK wants to find and use these hidden riches.
The Royal Mint, which makes British coins for the government, has agreed to work with the Canadian clean tech startup Excir to use a “world-first technology” that can safely get gold and other precious metals out of electronic waste (e-waste) and recycle them.
Electronic devices have circuit boards that have small amounts of gold in their connections because gold is a good conductor. These boards also have useful metals like silver, copper, lead, nickel, and aluminum.
In the past, getting the metals was hard, but Excir’s new technology can quickly and safely recover 99 percent of the gold that is trapped in electronic waste.
They prepare the circuit boards using a “unique process,” and then they use a patented chemical formula to quickly and selectively remove the gold. The liquid that is high in gold is then processed to make pure gold that can be melted down and formed into bars. Palladium, silver, and copper could also be recovered with this method.
“Our entrepreneurial spirit has helped the Royal Mint do well for over 1,100 years, and the Excir technology helps us reach our goal of being a leader in sustainable precious metals.” The chemistry is completely new and can get precious metals back from electronics in seconds. “It has a lot of potential for The Royal Mint and the circular economy, as it helps to reuse our planet’s valuable resources and creates new jobs in the UK,” said Sean Millard, Chief Growth Officer at The Royal Mint.
At the moment, about 22% of electronic waste is collected, stored properly, and recycled. But with this kind of new technology, the problem of old electronics could be lessened.
Every year, the world makes about 62 million metric tons of electronic waste, which is more than 1.5 million 40-tonne trucks’ worth. That number will go up by another 32% by 2030 as more people buy electronics. This will make it the fastest-growing source of solid waste in the world.
The World Health Organization says that e-waste is hazardous waste because it contains harmful materials and can leak harmful chemicals if it is not handled properly. For example, old electronics can release lead and mercury into the environment, which can affect the development of the central nervous system while a person is pregnant, as a baby, as a child, or as a teen. Also, e-waste doesn’t break down naturally and builds up in nature.
Aside from being a huge waste, this is also a big problem for the environment. There could be between $57 billion and $62 billion worth of precious metals in dumps and scrap yards.
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