• Independent cooling performance and system economy of A-CAES systems were studied.

• Three A-CAES systems were proposed for chilled water, cold air, and hybrid supply.

• Improved cooling capacity can reach 20.33, 40.05, and 45.05GJ in cooling season.

• A-CAES hybrid system was the optimum system for cooling supply.

Yuchen Jin @Yuchenj_UW

judging an engineer by age is BS

• Linus Torvalds wrote Linux at 21
• Steve Wozniak built Apple I at 25
• Palmer Luckey created Oculus VR at 20
• Vitalik Buterin designed Ethereum at 19
• Mark Zuckerberg coded Facebook at 19

Looking back, I realize that 18-25 is the peak time.

"The young do not know enough to be prudent, and therefore they attempt the impossible – and achieve it, generation after generation."

I spent many years conducting root cause analyses and teaching major corporate employees, mostly engineers, how to do root cause analysis. One of the tools for root cause analysis is what some call "5 Whys," but I always called a "Why-Why Analysis," as sometimes it may take two "Whys" and others, ten. In this case, there are too few houses. But they don't ask or answer the next question: Why? //

When asked, "How do you know when you've arrived at a root cause," my stock reply was, "When you arrive at the point where some person or group of people made a decision, that's likely to be your root cause." //

Percyisacat
4 hours ago
Where did they find 1100 sq feet for $2500 a month in Campbell?????? My son lived in Santa Clara, and paid over $3,000 a month for rent.

This calculator determines the absolute pressure at the pump impeller. NPSHA must exceed the NPSHR (net positive suction head requirement specified by the pump manufacturer or caviation and/or loss of prime will occur.

The first form calculates the pressure or friction loss along a given length of pipeline with a specified inside diameter. The second form calculates the minimum pipe size to limit pressure loss to a specified value.

Additional friction pressure losses occur due to fittings. These losses in-effect add extra additional length to the total pipeline. Use this calculator to estimate how much additional length needs to be added to the overall pipe length below in order to estimate these additional losses. Learn more about the units used on this page.

Here's the math behind making a star-encompassing megastructure.

In 1960, visionary physicist Freeman Dyson proposed that an advanced alien civilization would someday quit fooling around with kindergarten-level stuff like wind turbines and nuclear reactors and finally go big, completely enclosing their home star to capture as much solar energy as they possibly could. They would then go on to use that enormous amount of energy to mine bitcoin, make funny videos on social media, delve into the deepest mysteries of the Universe, and enjoy the bounties of their energy-rich civilization.

But what if the alien civilization was… us? What if we decided to build a Dyson sphere around our sun? Could we do it? How much energy would it cost us to rearrange our solar system, and how long would it take to get our investment back? Before we put too much thought into whether humanity is capable of this amazing feat, even theoretically, we should decide if it’s worth the effort. Can we actually achieve a net gain in energy by building a Dyson sphere? //

Even if we were to coat the entire surface of the Earth in solar panels, we would still only capture less than a tenth of a billionth of all the energy our sun produces. Most of it just radiates uselessly into empty space. We’ll need to keep that energy from radiating away if we want to achieve Great Galactic Civilization status, so we need to do some slight remodeling. We don’t want just the surface of the Earth to capture solar energy; we want to spread the Earth out to capture more energy. //

For slimmer, meter-thick panels operating at 90 percent efficiency, the game totally changes. At 0.1 AU, the Earth would smear out a third of the sun, and we would get a return on our energy investment in around a year. As for Jupiter, we wouldn’t even have to go to 0.1 AU. At a distance about 30 percent further out than that, we could achieve the unimaginable: completely enclosing our sun. We would recoup our energy cost in only a few hundred years, and we could then possess the entirety of the sun’s output from then on. //

MichalH Smack-Fu Master, in training
4y
62

euknemarchon said:
I don't get it. Why wouldn't you use asteroid material?
The mass of all asteroids amounts to only 3% of the earth's moon. Not worth chasing them down, I'd guess. //

DCStone Ars Tribunus Militum
14y
2,313
"But [Jupiter]’s mostly gas; it only has about five Earth’s worth of rocky material (theoretically—we’re not sure) buried under thousands of kilometers of mostly useless gas. We'd have to unbind the whole dang thing, and then we don’t even get to use most of the mass of the planet."

Hmm. If we can imagine being able to unbind rocky planets, we can also imagine fusing the gas atmosphere of Jupiter to make usable material (think giant colliders). Jupiter has a mass of about 1.9 x 10^27 kg, of which ~5% is rocky core. We'd need to make some assumptions about the energy required to fuse the atmosphere into something usable (silicon and oxygen to make silicates?) and the efficiency of that process. Does it do enough to change the overall calculation though? //

Dark Jaguar Ars Tribunus Angusticlavius
9y
11,066
The bigger issue is the sphere wouldn't be gravitationally locked in place because the sun is cancelling it's own pull in every direction. Heck even Ringworld had to deal with this flaw in the sequel. That's why these days the futurists talking about enclosing the sun recommend "Dyson swarming" instead.

Edit: A little additional note. You can't really get the centrifugal force needed to generate artificial gravity across an entire sphere like you can with a ring. A swarm doesn't negate this. If you orbit fast enough to generate that artificial gravity, you're now leaving the sun behind. Enjoy drifting endlessly! No, rather each of these swarm objects are just going to have to rotate themselves decently fast.

A few months ago, our AM radio hot dog experiment went mildly viral. That was a result of me asking my Dad 'what would happen if you ground a hot dog to one of your AM radio towers?' He didn't know, so one night on the way to my son's volleyball practice, we tested it. And it was awesome.

There's a video and some pictures in my hot dog radio blog post from back in March.

Fast forward a few months and one Open Sauce later, and Jay from Plasma Channel visited us in St. Charles, MO, for round two—where my Dad and I were prepared to measure (almost) everything: SWR, RF forward power, SDR on site, AM field intensity 25km (16mi) away, meat thermals, and—courtesy of Jay—some taste testing!

Industrial networking is vital to today’s manufacturing landscape. From different types of networks to key components and best practices, this guide will help you navigate the intricacies of industrial Ethernet networking. See video.

“We just had a midair,” the pilot of the Hawker is heard saying in an audio recording posted on LiveATC.net, which shares live and archived recordings of air traffic control radio transmissions.

Someone in the control tower responds by saying, “Say what?”

“You guys cleared somebody to take off or land, and we hit them on a departure,” the Hawker pilot says.

The recent accident in Houston is just the latest noteworthy instance in what a major New York Times investigation this summer determined to be “an alarming pattern of safety lapses and near misses in the skies and on the runways in the USA.” According to internal records of the Federal Aviation Agency, the Times reported that these safety lapses and near misses occurred as a “result of human error.” The Times report further revealed that “runway incursions” of the sort described above have nearly doubled, from 987 to 1732, despite the widespread proliferation of advanced technologies. //

While the disturbing decline in aviation safety is complex and multifaceted, we identified two major contributing factors that have received scant media attention. The first such factor is the likely contribution of disastrous COVID-era policies to the staffing shortage of many air traffic control rooms. The second factor is that aggressive affirmative action policies implemented during the Obama administration have resulted in a catastrophic collapse in the quality of controllers. In short, COVID policies have gutted the quantity of air traffic controllers, and diversity policies have gutted the quality of air traffic controllers, creating unprecedented danger for the aviation industry. //

The implications of these findings reach far beyond the scope of aviation, as important as this industry is. Rather, the collapse of the aviation industry must be understood in the context of a broader collapse in our ability to maintain the infrastructure of a First World society. This is a major and significant trend that we highlighted years ago in our coverage of the repeated failures of Texas’ electric power grid.

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Bridge collapses put transportation agencies’ emergency plans to the test
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Agencies need to build or find excess vehicle capacity before a bridge fails.

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Ars Legatus Legionis
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11,941
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Yesterday at 3:52 PM
#161
rabidk said:
As a practicing long-span bridge engineer, this is absolutely correct. It is not feasible to economically design a bridge to directly resist vessel impact.

It comes down to energy transfer and dissipation. Based on fundamental physics, the force of the impact is a function of mass times acceleration, or rate of change of distance over time (F = MA = ML*t^2) . The longer the vessel is deaccelerated, the smaller the force.

The Notre Dame cathedral in Paris has been undergoing extensive renovation in the wake of a devastating 2019 fire. Previously hidden portions of its structure have revealed the use of iron reinforcements in the earliest phases of the cathedral's construction, making it the earliest known building of its type to do so. //

“Compared to other cathedrals, such as Reims, the structure of Notre Dame in Paris is light and elegant,” Jennifer Feltman of the University of Alabama, who was not involved in the research, told New Scientist. “This study confirms that use of iron made this lighter structure at Paris possible and thus the use of this material was crucial to the design of the first Gothic architect of Notre Dame.”