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Differential voltage analysis as a tool for analyzing inhomogeneous aging: A case study for LiFePO4|Graphite cylindrical cells

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Publication date: 15 November 2017
Source:Journal of Power Sources, Volume 368
Author(s): Meinert Lewerenz, Andrea Marongiu, Alexander Warnecke, Dirk Uwe Sauer
In this work the differential voltage analysis (DVA) is evaluated for LiFePO4|Graphite cylindrical cells aged in calendaric and cyclic tests. The homogeneity of the active lithium distribution and the loss of anode active material (LAAM) are measured by the characteristic shape and peaks of the DVA. The results from this analysis exhibit an increasing homogeneity of the lithium-ion distribution during aging for all cells subjected to calendaric aging. At 60 °C, LAAM is found additionally and can be associated with the deposition of dissolved Fe from the cathode on the anode, where it finally leads to the clogging of pores. For cells aged under cyclic conditions, several phenomena are correlated to degradation, such as loss of active lithium and local LAAM for 100% DOD. Moreover, the deactivation of certain parts of anode and cathode due to a lithium-impermeable covering layer on top of the anode is observed for some cells. While the 100% DOD cycling is featured by a continuous LAAM, the LAAM due to deactivation by a covering layer of both electrodes starts suddenly. The homogeneity of the active lithium distribution within the cycled cells is successively reduced with deposited passivation layers and with LAAM that is lost locally at positions with lower external pressure on the electrode.

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steingart
18 days ago
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Princeton, NJ
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Refresh Is Sacred

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There are two kinds of client applications: The first kind has a “refresh” or “reload” button to make sure your app’s in sync with its server’s view of the world. The second kind is broken.

Refresh

Of late, I have to deal regularly with several apps, notably including an emailer and a car-sharing service, that lack such a button. I can imagine why — a customer-focused product manager said “Steve Jobs taught us that fewer controls are better and we should just take care of making sure we’re in sync with the cloud. So lose the button.”

Except for, it doesn’t work. Apparently nobody in the world is smart enough to arrange for flawlessly reliable hands-off client/cloud synchronization. There are times when you just know that what you’re seeing on the screen is wrong and if the stupid app would just assume its world-view is stale and ask for a brain transplant from its server, things would be OK.

The car-share app is particularly aggravating, showing me a map dotted with nearby vehicles when I know for sure that this time of day I’ll be lucky if there’s even one within walkable distance. Since it totally refuses to sync, I have to switch to the Android “recents” screen and kill it. When I re-open the app, it’s OK.

Why might this happen? Well, maybe switching from WiFi to cell data (or vice versa) left some layer confused about network truth. Possibly, because your app was written in a programming language with multiple threads and shared mutable state (silly, silly programmer), the cache is malfunctioning. Maybe that same thing happened on the server. Or in the CDN. Or maybe there’s an obscure hiccup in a distant node_modules dependency that you’re tickling.

Dear product managers: Show some humility. When a customer really thinks your app is wrong and they know how to fix it, don’t get in their way.

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steingart
19 days ago
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just pull down?
Princeton, NJ
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Trump is terrorizing America and should be removed from office

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Poet and English professor Seth Abramson recently published a Twitter thread about his current understanding of Donald Trump: his deliberate terrorization of the American public, lack of policy positions, corruption, and keen understanding of America as “a chaos machine” that “spits out attention, headlines, sometimes money” when you feed it. I think Abramson is right about Trump in many respects and I’ve included a few excerpts below…it was difficult to pick out what to highlight.

We need to never again discuss this man with respect to policy — it’s become more than clear in 9 months that he holds no policy positions.

So if you support Donald Trump because of any view you claim he holds, I don’t ever want to hear from you again. The man holds no views.

There is no position Donald Trump has ever taken that he has not, at some point in the past or present, taken the opposite position to.

But the most important thing is this: this is the first U.S. president to systematically and willfully terrorize his own populace daily.

His changeability is intended to keep us anxious and on guard. In fact, he’s admitted publicly, many times, that this is a tactic of his.

His corruption is equally studied: his business model has always been “get away with what you can,” and that’s exactly how he’s governed.

It’s *more* than that he’ll go down in our history as the worst president we’ll ever have — he’ll go down as one of our greatest villains.

Benedict Arnold tried to betray America for a prior sovereign — Trump is trying to *torture* a nation that was good to him his whole life.

Have you noticed a change in your mood since January? I mean a change you can’t seem to escape? Anxiety, anger, fear, confusion, doubt?

The most ubiquitous man in your nation is trying to poison you daily — because it gives him power — and no one’s stopping him from doing it.

I’m not using hyperbole: you’re under attack. A deliberate, unprovoked, systematic, and — yes — evil attack. And it’s working. We’re losing.

Because the last thing — of the three I mentioned — humans look for in a crisis is hope, and he’s systematically taking *that* away as well.

We don’t have hope future elections will be fair. We don’t have hope our government is working in our interests. We don’t have hope we can trust and love our neighbors and they’ll trust and love us back. And we don’t have hope things will start to make sense again.

Abramson finishes by saying that we need to focus on “legally, peacefully and transparently” removing Trump from power. I’m probably going to get some email about this post,1 so I might as well go all in here with a ludicrous-sounding hunch2 I’ve had about Trump since before the election: not only will he not resign or be impeached (for Russia ties or otherwise), he will refuse to leave office under any circumstances. He will attempt, with a non-zero chance of success, to stay in power even if he’s not re-elected in 2020.

Obviously, this is ridiculous and will not happen. What about laws and precedence and democracy and social mores, you’ll say! And you’d be correct. But Trump’s got more than 3 years to lay the groundwork to make it seem normal for him to do this…and Fox News and the Republicans will let him and aid him if they can. (I mean, if you’re America’s increasingly authoritarian & extremist minority party struggling to stay in power, making the sitting Republican President not subject to an election is far more effective than suppressing the votes of likely Democratic voters through gerrymandering and voter ID laws.) Sure, we’ll be outraged about it, but we’re outraged about him anyway and that hasn’t seemed to matter in a significant way yet.

Ok, that’s nuts, right? Could never happen in America, yes? But watching Trump as President over the past few months, is it really that difficult to imagine him going full OJ here when confronted with losing his powerful position? Instead of Simpson being driven around LA in the white Bronco by Al Cowlings followed by a phalanx of police cruisers, on January 20, 2021, it’ll be Trump locked in the White House with Senator Kid Rock, taunting the military via Twitter to come in and get him.3 That sounds more plausible than Trump genteelly hosting the incoming Democratic President for tea in what USA Today calls “the 220-year-old ritual that has become a hallmark of American democracy: The orderly transition of power that comes at the appointed hour when one president takes the oath of office and his predecessor recedes into history”. Aside from “power”, not a single other word in that sentence even remotely describes anything Trump has ever cared about.

  1. I always get email about my Trump posts. Political posts on kottke.org are pretty unpopular and lose me readers every single time. Stay in your lane, Kottke!

  2. Or perhaps “speculative fiction” is a better descriptor? I’m way too level-headed to actually believe this. Aren’t I?!

  3. Seriously though, what is the enforcement mechanism surrounding the transfer of power here? The 20th Amendment covers the beginnings and ends of terms and what happens when there’s no president-elect. But what about if a sitting President refuses to leave office? A lot of this stuff is ritual, presumably because of course (of course!!!!) the President is supposed to be a decent person who will honor tradition and democracy. Does Congress decide what to do? Does the Secret Service? The Supreme Court? The military? Can you imagine the cries of “coup” from Trump and his supporters if a bunch of Marines storm the White House? OMG, he’d love it.

Tags: Donald Trump   legal   politics   Seth Abramson
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steingart
20 days ago
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accurate
Princeton, NJ
satadru
18 days ago
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New York, NY
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2 public comments
JimB
17 days ago
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But the most important thing is this: this is the first U.S. president to systematically and willfully terrorize his own populace daily.
deezil
20 days ago
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Kottke went with some darkest timeline type shit here.

I'm both terrified of it actually happening, and amused he thinks of the things he does.
Louisville, Kentucky

Taking a knee

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Late last week, Donald Trump called any NFL player who kneels during the national anthem protesting police brutality a “son of a bitch” (recall that this is the President of the United States we’re talking about here) and said they should be fired (Ha! He said his catchphrase! From that TV show!). Naturally, NFL players took exception to this and over the weekend, many many more players kneeled, sat, or no-showed during the anthem. And there were many takes, from political commentators and sports journalists alike. One of the best was from Dallas sports anchor Dale Hansen, who deftly cut to the core of the matter in a short monologue:

Donald Trump has said he supports a peaceful protest because it’s an American’s right… But not this protest, and there’s the problem: The opinion that any protest you don’t agree with is a protest that should be stopped.

Martin Luther King should have marched across a different bridge. Young, black Americans should have gone to a different college and found a different lunch counter. And college kids in the 60’s had no right to protest an immoral war.

I served in the military during the Vietnam War… and my foot hurt, too. But I served anyway.

My best friend in high school was killed in Vietnam. Carroll Meir will be 18 years old forever. And he did not die so that you can decide who is a patriot and who loves America more.

The young, black athletes are not disrespecting America or the military by taking a knee during the anthem. They are respecting the best thing about America. It’s a dog whistle to the racists among us to say otherwise.

They, and all of us, should protest how black Americans are treated in this country. And if you don’t think white privilege is a fact, you don’t understand America.

Here’s a text transcript…it’s worth reading or watching. See also Bob Costas’ interview on CNN and Shannon Sharpe’s comments.

Tags: Bob Costas   Dale Hansen   Donald Trump   NFL   politics   racism   Shannon Sharpe   sports   video
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steingart
21 days ago
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Princeton, NJ
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2 public comments
wmorrell
21 days ago
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This guy. He does good. https://www.youtube.com/watch?v=Pjc6QlIdGg4
deezil
21 days ago
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I shared this on Twitter last night and I still love it so much. This is a veteran (who we're supposedly offending) in Texas (red-bleeding state if there ever was such) who is on the correct side of the debate. The dog whistle comment is the whole reason this argument and "offense" exists. Because a person of color decided to speak out, it's time to rouse some rabble.
Louisville, Kentucky

List: Everything You Know About Me, the Female Character You’re Falling in Love With in a Romantic Film/TV Show Written by a Man

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1. I’m incredibly beautiful but it’s an accident, I swear!

2. I love Jane Austen if this is a comedy or the Brontë sisters if this is a drama.

3. I eat a lot lol.

4. I love listening to music almost as much as I love listening to you talk about music.

5. I’m smart but not as smart as you.

6. I’m extremely knowledgeable about exactly one subject.

7. I have a great sense of humor, by which I mean ha-ha you’re so funny.

8. I’m not funny, but I am hilariously adorable when I get stressed out.

9. I have only one friend. Now she is funny.

10. I seem mysterious, but that’s just because I have almost no personality whatsoever.

11. My ex-boyfriend is a jerk or maybe just boring.

12. I’m so nice.

13. When I’m sad, I drink wine alone.

14. I live well beyond my means in a beautiful apartment, but it’s somehow not an issue.

15. I lose my ability to walk in high heels when I get angry.

16. I really like you even though I shouldn’t do to some extenuating circumstance.

17. My parents are complicated and/or dead.

18. I have a vaguely creative job that I seem to be good at but that’s not the point.

19. I believe in you!

20. I’d love to travel but haven’t had a chance to for some reason, probably because this is a metaphor for my lack of life experience, so instead I constantly talk about all the places I want to visit, probably because that’s a metaphor for my desire to break out of my shell and finally start Living.

21. I’m not perfect, which you know not because of my actions, but because I very dramatically told you so once.

22. If I’m half as wonderful as I seem, I’ll get sick of your shit and dump you very soon.

23. This is the most I’ve ever talked about myself! Normally I’m just listening to you or talking about that one subject I’m an expert in.

24. I will save you but don’t worry, you’ll still be the hero of this story.

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steingart
22 days ago
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too real
Princeton, NJ
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Are we living in a simulation?

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In the 1990s, futurist and AI researcher Hans Moravec suggested that our Universe might be a simulation.

Assuming the artificial intelligences now have truly overwhelming processing power, they should be able to reconstruct human society in every detail by tracing atomic events backward in time. “It will cost them very little to preserve us this way,” he points out. “They will, in fact, be able to re-create a model of our entire civilization, with everything and everyone in it, down to the atomic level, simulating our atoms with machinery that’s vastly subatomic. Also,” he says with amusement, “they’ll be able to use data compression to remove the redundant stuff that isn’t important.”

But by this logic, our current “reality” could be nothing more than a simulation produced by information entities.

“Of course.” Moravec shrugs and waves his hand as if the idea is too obvious. “In fact, the robots will re-create us any number of times, whereas the original version of our world exists, at most, only once. Therefore, statistically speaking, it’s much more likely we’re living in a vast simulation than in the original version. To me, the whole concept of reality is rather absurd. But while you’re inside the scenario, you can’t help but play by the rules. So we might as well pretend this is real - even though the chance things are as they seem is essentially negligible.”

And so, according to Hans Moravec, the human race is almost certainly extinct, while the world around us is just an advanced version of SimCity.

In 2003, philosopher Nick Bostrom examined the matter more closely:

This paper argues that at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation.

In the above (as well as in this follow-up video by Vsauce 3), Kurzgesagt explores these ideas and their implications. Here’s the one that always gets me: If simulations are possible, there are probably a lot of them, which means the chances that we’re inside one of them is high. Like, if there’s one real Universe and 17 quadrillion simulated universes, you’re almost certainly in one of the simulations. <neo>Whoa.</neo>

Tags: Hans Moravec   Nick Bostrom   science   video
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steingart
26 days ago
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JFC kotkot, the only thing that makes we're living in a simulation is that one asks "are we living in a simulation" like it's the first time its ever been asked
Princeton, NJ
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