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Published: Tuesday, 17 October 2023 00:41

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Human Anatomy

Here we'll learn about all major parts of human body, and how they work in tandem.There are different sections dedicated to different parts of human body as digestion, respiration,brain, muscles, etc.

There's this book on human anatomy that's very good book to get started. => https://www.amazon.com/Complete-Human-Body-Alice-Roberts/dp/0744073677

It's on sale and can be had for a dollar or two. Few deals:

• 10/11/2023: Electronic version is on sale for $1 (cheapest ever): https://slickdeals.net/f/16974181-human-anatomy-atlas-2023-complete-3d-human-body-ios-or-android-app-0-99-via-apple-app-google-play-store?src=frontpage
• 01/01/2023: It's on sale for $2 (for electronic version): https://slickdeals.net/f/16352716-the-complete-human-body-the-definitive-visual-guide-1-99-kindle-edition-1-99?src=frontpage

You can also find it for free here: https://archive.org/details/AliceRobertsTheCompleteHumanBodyDKPublishing2016/page/n62/mode/2up

You can download each page individually as jpeg image, so no need to pay anyone anything. Enjoy free education !! (It has since been taken down, so need to move to other free resources)

Bunch of Free Resources on Human Body:

• Khan Academy Medicine => https://www.youtube.com/@khanacademymedicine
• Dr John Campbell Videos (lots of hand drawn diagrams) => https://www.youtube.com/@Campbellteaching
• Sam Webster => https://www.youtube.com/@SamWebster

 Good vid on Lungs, Trachea and Heart (with a human body model) => https://www.youtube.com/watch?v=XzmvG3pgRVo

 In following sub sections, you will find devoted material on body parts as:

• Brain
• Heart
• Lungs
• Kidneys
• Liver
• Human cells
• Blood
• Hormones
• Bones/Muscles

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Published: Saturday, 07 October 2023 18:12

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Success Recipe to be Maaldaar:

This is a sample recipe to be Successful in life. Success may mean "to be rich" or "to be knowledgeable" or just "to be happy". Info below has been collected from multiple sources.

• Prioritize your health: This is the number one advise given by Warren Buffett. Health is the most important asset you have, so devote time to it. Make sure that you do things that keep you healthy.
• Be a lifelong Learner: This is one skill that separates winners from losers. Successful always keep learning. Just a few mins a day learning new words, new language, new game, new topic, etc can do wonders to your brain. On "CNBC Make It", it was reported that 71% of self made millionaires often read "self help" books, i.e instead of hiring someone to do something, learn it yourself so that you'll be more knowledgeable in it.
• Listen more, talk less: This is another skill that's very hard to gain. Why? Because we all like talking. Self Made milliorares have 5:1 rule => For every minute they talk, they listen for 5 minutes. You should constantly seek feedback from people around you in order to improve yourself.
• Build a team: Focus on your strength and outsource your weakness. Basically, always surround yourself with people smarter than you.
• Hard Work and Luck go together: A lot of people work hard, but aren't as successful. Luck is a needed ingredient for you to be successful. Realize that and keep working.
• Jealousy and Grudge: These are 2 skills you don't want to have, because they fail the homo sapiens species. "Never hold a grudge against somebody, because it poisons you and the other person won’t even remember,” says Katalin Karikó, a biochemist and researcher, who won the Nobel Prize in Physiology and Medicine in 2023.

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Published: Tuesday, 26 September 2023 01:51

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Garage Door (GD):

Most of the new homes come with a garage and a garage door. If yours doesn't have a garage door, it's NOT something that can be done DIY. It requires a lot of muscles to move 100+ lbs doors, and a lot of precision to make it work. You are better off paying someone to do it, or live without a garage door. Once garage door is installed, there are 2 options: One to lift it up and then close it manually everytime you leave the house, or the other option is to have a "wireless or wired" garage door opener, that will open or close the door on click of a button. Installing these garage door openers may be a DIY if you have those steel brackets already hanging from the roof, where you can install your big box of "GD opener". Most Builders already have these "wireless or wired" GD openers installed, so you don't have to worry about. However, installing anything from scratch isn't a DIY when working on a GD. However, if something breaks or malfunctions, then it's definitely DIY to fix it.

GD basics:

GD are heavy (150 lbs or more). You will see 2 rails on 2 sides. There will be wheels rolling on these rails. The whole GD rolls on these wheels. There are 2 drums (big wheels) on 2 sides on the top, which have a cable attached to them which help in lifting or dropping the big GD. However, even with these pulleys, the heavy door can't be lifted vertically, as lifting 150 lbs weight to 5 feet height is not easy. To help with that, there is a spring (called as Torsion Spring) that is attached to the rod on top of the door. It is initially winded in a direction opposite to the direction the door is going to lift up. It's like you wind a spring 10 times, then it will unwind as soon as you let it go. If a weight is attached to the spring with a string, then unwinding spring will lift the weight. If the weight just counter balances the torque in the spring, then the weight will just stay where ever it is, i.e there will be no force needed to raise or lower the weight. This is exactly how garage door torsion spring works.

2 good video explaining this:

Part 1: https://www.youtube.com/watch?v=2yFhsl3s_4A

Part 2: https://www.youtube.com/watch?v=FzczI8Aq3AQ

Maintenance:

There are few DIY maintenance work that can contribute to longevity of your GD. Garage door tuneup Companies advertise these and charge you $100's of dollars to do this yearly. These can be done yourself for $10 or so. 

GD lubricant => Online consensus is to use Lithium based grease. The second best is Simicone based grease. Regular oil or any other lubricants shouldn't be used, as they may attract dirt and cause more problems down the line. Also, very few parts need to be lubricated, so don't go over the board. One such lubricant with good reviews is at both HomeDepot and Lowes. 

GD lubricant (HD) => https://www.homedepot.com/p/3-IN-ONE-11-oz-Garage-Door-Lube-with-Smart-Straw-Spray-2-Pack-611857/321712761

GD routine tuneup => https://www.youtube.com/watch?v=BTqjoWyH1Js

Repairs:

There are many DIY repairs that can be done. Hiring someone to do GD repair is expensive. Parts are very cheap, and can easily be bought for < $100 for most of them. Labot will cost around $200/hr.So, do yourself by watching same youtube videos again and again, and also all different videos on that topic.

Broken Torsion spring (TS) replacement:

One of the most common things to break in a GD is torsion spring. It has a life of 10 years, but they may break in as little as 5 years depending on usage. Hiring someone to replace the torsion spring costs about $400, while torsion spring itself costs only $50 (pair costs $100). You can buy from Home Depot, Lowes, etc. Look at your current TS and get the specs.

Larger 2 car GD TS specs => 0.2437 in x 2 in x 27.5 in. This is what my GD had. It only had 1 spring, which was a left wound one. So, that's what I got.

Smaller 1 car GD TS specs => 0.207 in x 2 in x 23 in. This is what my GD had

Torsion Spring (Left wound) for larger 2 car GD (HD): https://www.homedepot.com/p/Clopay-0-2437-x-2-in-x-27-5-in-Left-Wound-1-Green-Garage-Door-Torsion-Spring-4156574/331908053

Torsion Spring (Right wound) for smaller 1 car GD (HD): https://www.homedepot.com/p/Clopay-0-207-x-2-in-x-21-5-in-Right-Wound-2-Yellow-Garage-Door-Torsion-Spring-4156537/331908052

Winding Bars (HD): https://www.homedepot.com/p/Clopay-Commercial-spring-winding-bars-5686901/312648359

Smaller doors have only 1 spring, while larger doors have 2 springs. The Spring needs to make 7-8 complete turns. winding bars are used to make those turns. With each turn, the spring stores energy, and can be very dangerous if it suddenly loses that energy. So, be extremely careful.  Few tips:

• There is a straight white line on the Torsion spring. With each turn, the straight line will show a twist. So, 1 turn will show 1 circle of that white line. With 8 turns, it will show 8 circles of that white line. This is to help us figure out the number of turns we have given to the spring. For a 7 ft GD, I had to give 28 turns (7*4) + 3 turns = 31 turns. It worked perfectly. +/- 1 turn isn't going to make or break it. As long as the door is able to hold, it's good. When turning with the winding bars, it's not too difficult. I'm a thin person, but was able to do it with no issues.
• There are left and right torsion spring. Get the correct one, if you have only 1 spring. If you have 2 springs, then get both left and right, as you should replace both of them. Make sure you wind them in correct direction (i.e clockwise or anticlockwise). Both the springs turn the same way when looked at from the same side, as they both try to turn the rod in the same direction. But they reverse direction when you look at them from the end you are winding it from.

Video 1: https://www.youtube.com/watch?v=5k9qrgZ9rPs

Garage Door Open/close issues:

This is one of the most common issues, where garage door will open fine, but will not close. It will try to go down an inch or 2, and then lights starting flashing, or it will go half way down, and then open back up, or it will go almost almost all the way down (or even touch the ground), and then open all the way up. Most of the times it's an issue with the sensor, or an issue with an adjustment knob on the controller system. Both of them pretty easy to fix.

First, make sure that by bypassing the sensor, you are able to close the door. Bypassing the sensor can be done by pressing the "garage opening button" mounted on the wall (one to open/close the garage door), and keeping it pressed, until the garage door closes. If it does, then it's one of the 2 issues:

1. Sensor issues: These are the 2 sensors (Sensor pair) mounted on the bottom of the 2 rails on the 2 sides of the garage door. One of them is the one sending the IR light, while the other one is receiving the light. If there's anything in between the 2 sensors (such as a person or car ), then the receiving sensor doesn't get the IR light, and garage door won't close. The light on the controller will blink 10 times to indicate an obstruction. Sometimes, sensors get misaligned, and not seeing seeing each other. You need to loosen them and then get them to see each other. One of the sensors which is transmitting IR light will be lit orange, while the receiver will lit solid green. If it's blinking, then it's not in line of sight. Adjust it until it's solid green. Then tighten it to keep it in place and check if garage door will close. Many times, sensors will have dirt or something on the lens which will need to be cleaned with a cloth. If it still doesn't work, then tr replacing the sensors, as old sensors may show solid green light, but may still malfunction. Replacing the sensor is easy 5 minute job, and quick way to find out if sensors are the issue. You may return the sensors if you figure out that replacing sensors did nothing.
   1. Video on replacing sensors =>
2. Adjustment via controller: If even after fixing the sensor, the GD still doesn't close all the way or remain open halfway, then it's most likely adjustment issue. There's an adjustment knob on all controllers, that allow you to adjust how much door you want to open or how much you want to close. The door will stop at that point. Each system has it's own method to adjust the knob. You have to take a ladder and get to the control system to adjust it. No parts needed, as it's usually a simple push button or a screw to turn around (use a screwdriver to turn it).
   • Adjustment for Chamberlain => https://www.youtube.com/watch?v=M6d9IMjyze4. Direct from Chamberlain => https://www.youtube.com/watch?v=P7HTQQ11sPE . Four Steps for this procedure. Close the GD. Now open the cover and locate the center push button (aka adjustment button) and up/down arrow buttons.
     1. Push button in center for a second. Light for top arrow will start blinking. Push the top arrow button and keep it pushed, until it's to a point where you want your GD to remain when opened. Now push button in center. There will be a beep and Lights will blink. This will set the desired setting for open position of GD.
     2. Now the down arrow will be blinking. Push the down arrow button and keep it pushed, until it's to a point where you want your GD to remain when closed. This is generally the point where the GD touches the floor. Now push button in center. There will be a beep and Lights will blink. This will set the desired setting for closed position of GD.
     3. Now the up arrow will blink again. You push it, and it should allow the door to open until it gets to the open position that you set. You should NOT press the central rectangular button in this step or the next, as setting is already done. Step 3 and step 4 are just to cycle thru.
     4. Now the down arrow will blink again. You push it, and it should allow the door to close until it gets to the closed position that you set. Light will stop blinking, implying the whole setup is complete. Now you close the cover, and try opening/closing GD from GD opener on the wall. If you messed up something, start from step 1 again. To test that GD will open if it comes in contact with anything while it's in between these 2 positions, place a wooden piece (~1 inch or so) on the floor. Now close the GD, GD should reverse and open on coming in contact with this wooden piece. Lights will blink indicating an obstruction. The test is complete at this point.
   • Adjustment for LiftMaster => This is also owned by Chamberlain, but has a different style of knob for adjusting. Video her: https://www.youtube.com/watch?v=uSyI-zbpxEc&list=TLPQMTAxMDIwMjMANt1Sc1eWEg&index=2

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Published: Sunday, 10 September 2023 19:58

Hits: 1274

Linux Audio

Audio and wifi are the 2 things you need to be working for any system to be usable. Audio is something that's giving me problems with Linux distro CentOS 7 (as of Sept 2023), so I thought to add this section

Background:

Basic info: https://linuxhint.com/guide_linux_audio/

Below I show the general Liux Audio Architecture. Though the contents are taken from QNX link below, it applies to all architectures.

Link for QNX (NOT alsa): https://www.qnx.com/developers/docs/6.4.1/neutrino/audio/architecture.html

In order for an application to produce sound, the system must have these 3 components:

• Hardware: This is in the form of a sound card or sound chip. The basic piece of hardware needed to produce or capture (i.e. record) sound is an audio chip or sound card, referred to simply as a card. Linux Arch can support more than one card at a time, and can even mount and unmount cards “on the fly”. All the sound devices are attached to a card, so in order to reach a device, you must first know what card it's attached to. Each sound card has multiple devices. /dev/snd/ shows all the devices. 3 most common sound devices present in each sound card are:
  
  1. Control device: There's one control device for each sound card in the system. This device is special because it doesn't directly control any real hardware. It's a concentration point for information about its card and the other devices attached to its card. The primary information kept by the control device includes the type and number of additional devices attached to the card.
  2. Mixer devices: These are responsible for combining or mixing the various analog signals on the sound card. A mixer may also provide a series of controls for selecting which signals are mixed and how they're mixed together, adjusting the gain or attenuation of signals, and/or the muting of signals.
  3. PCM (Pulse Code Modulation) devices: These are responsible for converting digital sound sequences to analog waveforms, or analog waveforms to digital sound sequences. Each device operates only in one mode or the other. If it converts digital to analog, it's a playback channel device; if it converts analog to digital, it's a capture channel device.
• Device driver: for the hardware
• API (Application Programming Interface): a well-defined way for the application to talk to the driver, in the form of an API.

 Centos-7: ls /dev/snd/ => controlC0 (Control device) hwC0D0  pcmC0D3p  seq  timer

ALSA: Advanced Linux Sound Architecture

ALSA is a software framework included with Linux Kernel which provides an API for sound card device drivers. So, basically we don't have to call device driver functions,but instead call ALSA API. ALSA was introduced with Kernel 2.6 onwards (year 2002) and replaced the older OSS (open sound system), though it does provide support for OSS too.

Linux Audio Architecture: https://www.thewelltemperedcomputer.com/Linux/AudioArchitecture.htm

Official site: https://www.alsa-project.org/

ALSA provides fully modularized Sound drivers. It also provides User space library (alsa-lib) to simplify application programming and provide higher level functionality. ALSA native applications communicate with ALSA library (outside of kernel) via ALSA lib API, which then communicates with ALSA kernel API (inside of Kernel) which in turn talk to ALSA kernel drivers, which finally communicate with real sound hardware.

PulseAudio:

Our applications never interact with ALSA directly, but instead we use another application called PulseAudio that is the user facing interface in most linux distro. PulseAudio sound server provides further tools to better control our sound system. This is done with modules to define volume levels, audio card profiles, output sinks, or input sources, and more for easy access from most Ubuntu applications. Like ALSA, PulseAudio is also designed to run with as few user interactions as possible. Whenever we need to change volume, balance, or input/output devices, it is a PulseAudio module or application we or our application call. PulseAudio is the interface engine between applications and ALSA. However, its use is not mandatory and audio can still be played and mixed together without PulseAudio.

A professional alternative to PulseAudio is the JACK audio server, with more options to interact with our sound hardware and a better low latency support. Only few music production applications expect to have JACK running, which can be done in parallel to PulseAudio.

To see modules loaded by ALSA, we can use lsmod cmd:

lsmod | grep snd => this shows about a dozen snd alsa modules. Imp modules are: snd_hda_intel, snd_seq, snd_pcm, snd_timer,

snd_hda_codec_hdmi     52340  1
snd_hda_intel          40390  2
snd_hda_codec         136355  2 snd_hda_codec_hdmi,snd_hda_intel
snd_hda_core           91007  3 snd_hda_codec_hdmi,snd_hda_codec,snd_hda_intel
snd_hwdep              13608  1 snd_hda_codec
snd_seq                62774  0
snd_seq_device         14356  1 snd_seq
snd_pcm               101339  4 snd_hda_codec_hdmi,snd_hda_codec,snd_hda_intel,snd_hda_core
snd_timer              30014  2 snd_pcm,snd_seq
snd                    83987  12 snd_hwdep,snd_timer,snd_hda_codec_hdmi,snd_pcm,snd_seq,snd_hda_codec,snd_hda_intel,snd_seq_device
soundcore              15047  1 snd