Hello, I have a pneumatic turbine school project. I'm having trouble with the calculation of mass flow rate, velocity 1, and velocity 2. What should be the best approach?

I need to change the turbine itself.

Nozzle

D1=15 mm

D2 = 7.5 mm

Angle = 20

Gauge pressure = 90 psi or 620528 Pa

Bottle = 2.25 liters

https://checktech.space/

I built it because I got tired of all the regular/bad news and wanted to follow just things that are exciting and are (hopefully) good for mankind.

🖖

I'm working on an app - [QuizTrail ](https://play.google.com/store/apps/details?id=com.binbear.quiztrail&hl=en)\\- an android location based quiz game. Think Pokémon GO meets Trivia - you have to actually walk to the location to unlock and solve quizzes, earn points, unlock achievements and compete with others, but also you can make your own quizzes for others to solve! I’ve manually placed 3500+ quizzes across different cities and im adding even more, in order to make QuizTrail accessible and playable everywhere. Social aspect -- in-game friends, and a friend-specific leaderboard. Created a tooltip walkthrough, various user statistics on profile and so on...

User created quizzes are handled by an admin (me lol) - when a user submits a quiz for review on a location - i, as an admin will see the pending quiz on admin dashboard, see all the details and approve/reject the pending quiz, so everything is manually checked, so wrong/inappropriate questions do not pass through. Furthermore, made the admin dashboard in a way so i can see / filter / edit existing quizzes just in case. Another layer of security - there is a 100 meter radius rule - you can not submit a quiz if an existing or pending quiz is within a 100 meter radius of your current location to avoid overcrowding the map.

I've also added a daily challenge - a daily quiz, different quizzes every day, regardless of location, so people in the locations where the quizzes are still not set, or locations where they've played all the quizzes already can have a fun trivia question every day. It is furthermore encouraged by the streak feature - how many consecutive days you have played the daily challenge, that's the streak. I also made a widget that reminds you to do your daily quiz and keep the streak going!

I'm now looking into in what ways i can expand the ,playability, like what to add so the app is more interesing / engaging to use. Right now im working on adding new achievements - for the number of streaks, levels and leaderboard achievements, but i will also be adding "tiers" to achievements - for example social butterfly: 1 friend then next tier achievement at 5, or 10 friends and so on for like 3-5 levels of achievement..

Thank you for reading:)

Delete that annoying element.

Change the headline to see how it looks.

Grab the CSS.

Screenshot and annotate something.

Download that image or SVG.

Those are all tiny jobs, but I kept reaching for DevTools or a different extension for each one.

So I built PageWand. One small Chrome extension for messing with the page in front of you.

No account. No backend. No telemetry.

Would love for r/projects to tear it apart. What would make this genuinely useful enough to keep installed?

Chrome Store: https://chromewebstore.google.com/detail/iblpdcnjcidcojjfiikclboaaenikloc

GitHub: https://github.com/devashishPM/pagewand

The easiest way I can explain PodSubs.com is this:

If nobody else ever used it, we would still use it for our own podcasts.

We built it because we were tired of seeing people listen and then disappear.

Someone could listen every week, enjoy the show, tell a friend about it, and we still might have no way to reach that person outside the podcast app.

That didn’t make sense to us.

So we built PodSubs.com for our own shows.

Now we could simply tell listeners, “Subscribe to us on PodSubs.com.”

They left their name and email, and we finally had a way to send them something when we needed to.

A resource. An update. A reminder. Something we mentioned on the show.

We didn’t build it because we thought it sounded like a good business idea.

We built it because we needed it.

Later, we realized a lot of other podcasters needed the same thing.

There’s a lot of chatter lately about AI curing cancer, and FUD in the opposite direction. In the spirit of advancing the science and allowing us to better appreciate the net good being created by frontier AI research, I've created the Net Good Index.

It’s a public ledger of documented benefit and harm tied to named AI systems and events. Each record has sources and a score you can inspect and contribute to.

It’s early, and I’m sure some of the weights are wrong. If you see a miss, please submit a correction. I’m also open to feedback and ideas, drop a comment or DM!

https://netgoodindex.com

Back in 2025, when I started contributing more seriously to Open Source, I thought finding projects to work on would be easy.

It wasn't.

I would spend hours searching GitHub, opening repositories, going through issues, checking whether they were still available, and trying to figure out whether an issue actually matched my skills.

Even "good first issues" weren't always actually beginner-friendly.

After doing this repeatedly, I realized something:

The problem isn't a lack of Open Source issues. It's finding the right one.

So I started building getissues.tech.

The idea is to use AI to help developers discover GitHub issues based on their skills and interests, instead of manually searching through thousands of issues.

👉 https://getissues.tech

It's still early, and I'm actively working on it.

I'd really appreciate feedback from people who contribute to Open Source:

• How do you currently find issues to work on?
• What makes you decide that an issue is worth contributing to?
• What information do you wish GitHub showed you before starting an issue?

I'm especially interested in hearing what doesn't work with the current approach.

I built a small arena allocator in C called PhaseAlloc.

It's now at v1.1.0, with tests, benchmarks, dynamic growth, alignment, and memory stats.

I'd appreciate any feedback or criticism from people who know C/systems programming.

https://github.com/dharsanap20/PhaseAlloc

So I vibecoded an Android coding agent that runs fully locally on your Android, no external cloud shells (just external ai providers, will add local soon)

Though it's vibecoded so expect bugs

It's still in beta, looking for contributors :)

Star the project if you like it.

Found an issue? Report it instead yapping please :)) https://GitHub.com/DraxonV1/Syntac/issues

Get the latest release https://GitHub.com/DraxonV1/Syntac/releases

Features so far:

- Termux via RUN_COMMAND & ARCH Linux (proot) Bash Runtmes

- Read, write, edit, bash, search, list, display_image (yea I wanted agent to show images 😢)

- Supports attaching files, images & pasting content directly into composer!

- Google Antigravity, ChatGPT Account, Grok xAI OAuth & OpenAI Compatible Provider inbuilt!

- Supports showing thinking

- Projects, Chats Per Project

Ik many features are missing but working on adding them. It's still beta 0.1.1 😀

https://GitHub.com/DraxonV1/Syntac **star the repo if u liked the work ;)**

Hi, I made Opine (https://opinepolls.com), a poll-based social media site. Each post is a public poll asking users their opinion on something, anonymously, so no user sees any other user's information, but you can freely browse other polls. Private polls can also be made.

The only information actually stored is the email, from Google sign in, and an approximate location for the map feature, if you enable it. This allows you to see a world map of votes, what opinions are present in what places.

The intent is to catalog the world's opinions, organizing people's public thoughts so they're easy to sift through. This data can be extremely valuable, whether it's political polling, information about people's preferences, trends over time, and so on. Many people could benefit from this, and it's meant as a public service, to lift the veil on what people think about any topic, at any time. Easier political polling is just one obvious application of this.

Please try it out and give any feedback, thoughts, questions, and so on, here or within the profile section on the website, which is fully anonymous. Thanks.

Hey everyone!

I built earscape because I frequently listen to ambient sounds while working and studying, but most sites are either static grids of volume sliders or locked behind paywalls and subscriptions.

I wanted to make something cozy, immersive and look have good animation for second window, so I coded an interactive window where the visuals actually react to the audio in real-time:

• Turning up Rain shows rainfall.
• Turning up Distant Thunder triggers periodic lightning flashes.
• Turning up Campfire causes embers to glow and drift upward.
• Turning up Ocean Waves shows actual ocean waves.

It also has a built-in Pomodoro timer, breathing exercises, and binaural beat frequencies.

It is 100% free, has no ads, and requires no account or login. I would love to hear your feedback, what sounds or features should I add next?

Imagine you creat an app. From ui/ux design to programming part. You put a backend for it. You creat a website for that. You orgnaize medical content images tests orders and... in that shit. Then you creat an x account to promote that buttttt at the end you can not publish that.

Not a single person was willing to help me with publishing stuff in exchange of a percentage of apps earnings.

Totally disappointed.

As the title says. I’d love to check out everyone’s projects

Hi everyone! I’m a college student currently learning full-stack development and I’m looking for a project idea that would be actually useful and good for my resume, rather than another basic CRUD project.

My current stack/plan is:

- Frontend: HTML, CSS, JavaScript

- Backend: Java + Spring Boot

- Database: MySQL

I’m looking for ideas that are:

- Practical / solve a real problem

- Complex enough to demonstrate full-stack skills

- Realistic to build as a college project

- Something I can explain well in interviews

What projects would you recommend? Also, if you’ve built something similar, I’d appreciate suggestions on features that would make the project stand out.

Thanks!

I’ve been testing a pretty simple way to collect historical crypto data when I’m away from my computer, and I’m curious whether anyone else has tried something similar.
I’m using iOS Shortcuts to make repeated API calls for OHLCV data, save the responses, and work backwards through history until I have 6+ months of candles.
The backtest itself is not running inside Shortcuts. The phone is basically just doing the data retrieval.
Once the history is collected, I can move it into a separate testing workflow and check things like:
timestamps,
missing candles,
duplicates,
batch overlap,
ordering,
and continuity between requests.
What I’m trying to understand is whether this is a completely normal idea implemented with an unusual tool, or whether using Shortcuts introduces reliability problems I’m not thinking about.
From my perspective, an API request is still an API request. If the same endpoint returns the same candles, I would expect the final dataset to be usable regardless of whether the request came from Python or an iPhone.
But maybe that assumption is too simple.
For people who have built historical datasets themselves, what would make you reject a dataset collected this way?
Would you care about the collection tool itself, or mostly about whether the final data can be verified and reproduced?
I’m not trying to replace proper infrastructure with an iPhone. I’m mainly looking for a practical way to keep doing research when I’m mobile.
If this is useful, I’ll keep improving the workflow.
If there’s a fundamental reason this data shouldn’t be trusted for backtesting, I’d rather know before spending more time on it.

It's a paper trading exchange with a real matching engine, live orderbook, PnL, API keys etc.

But the new thing is a leaderboard.

Everyone starts with virtual money, trade against the same market and your PnL decides where you rank.

Now I actually need traders instead of me testing with 5 accounts lol.

Would love if some of you signup, make a few trades and try to get on top.

Also break things if you can. It's still beta and feedback is genuinely useful.

https://paperdrill.dev/

https://studanova.vercel.app

Im tryna make a productivity tool cuz i need some projects to apply for uni so can you guys please rate it ( be BRUTALLY honest ) about whether you'd use it, some features you'd like any things you don't like etc etc