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Quorten Blog 1

First blog for all Quorten's blog-like writings

Raspberry Pi peripheral classifications

quorten

2018-10-19

Categories: home-network   3d-scanner   3d-scanning   raspberry-pi   important  
Tags: home-network   3d-scanner   3d-scanning   raspberry-pi   important  

Let’s discuss the Raspberry Pi hardware that makes general measurement of a house not only possible, but accurate. It’s clear that what it comes down to for this use is using JST connectors to (1) make things easy to plug and remove in different combinations and (2) allow using arbitrary wire ends that are easy to solder together.

Okay, so new definitions for my Raspberry Pi sensor array. Okay, fine, I’ll list this in order, and try to group various sensors into practical applications, sorted by some order of their technical complexity and cost.

Tiny core sensor pod:

  1. JST connectors for GPIO push buttons
  2. PWM buzzer
  3. Weight sensor, force sensor, motor resistance sensor
  4. Microphone
  5. Environment temperature sensor (Raspberry Pi GPU temperature)
  6. Environment humidity sensor
  7. Temperature probe sensor

Barcode reader:

  1. Laser line illuminator
  2. Optical line sensor, 1D image sensor… where to get these?

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Does consuming alcohol really help you recover from a cold?

quorten

2018-10-18

Categories: misc  
Tags: misc  

Some of my coworkers were talking about drinking a mix of alcohol and water when you are sick is a cure to any illness.

35% Hot Water + 60% Alcohol + 5% Honey will gain victory over cold virus. Note: It is for medicinal purpose, ‘Minnesotan Fight Against Cold’, not recommended for habitual action

Is this really true? At face value, we know that alchohol can kill germs when it is used outside of the human body. But what exactly is the internal effect? As it turns out, internally alcohol weakens the immune system and is also causes dehydration. Not to mention it also has the typical observed mental effect of making people a little bit “tipsy” or “drunk.”

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How far away is the sewage treatment plant on average?

quorten

2018-10-15

Categories: world-building  
Tags: world-building  

Interesting. So, you’re wondering. How far is it between a typical city and the sewage treatment plant (Publicly Owned Treatment Works (POTW))? Well, this article does cover some metrics for one city, Raleigh, North Carolina. Basically, a typical sewage treatment plant is huge. It may be in the middle of a giant farming district, serving the combined output of many cities.

20181014/DuckDuckGo distance between city and sewage treatment plant
20181014/https://www.scientificamerican.com/article/treating-sewage/

Convert a VMDK disk image to an ESXi disk image

quorten

2018-10-13

Categories: unix   centos   vmware  
Tags: unix   centos   vmware  

Suppose you have a VMDK disk image, and you want to import that directly into an ESX host. How do you do that?

As it turns out, ESX hosts do not run off of VMDK disk images. You have to convert it to an ESX compatible format in order to be able to run it. ESX compatible format disk images are composed of two files: one *.vmdk file and another *-flat.vmdk file. The first file is the header, the second file is the disk image data itself.

So, here’s how I was able to successfully do it.

  1. Download and unzip -vdiskmanager-windows-7.0.1.exe2.zip for Windows from the linked VMware KB article. I couldn’t easily get the Linux one working because it was only 32-bit and I didn’t have a multiarch machine on hand, otherwise I’d prefer to use that one.

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Fastest measurement techniques for indoor surveys

quorten

2018-10-13

Categories: home-network   raspberry-pi  
Tags: home-network   raspberry-pi  

So, now it’s obvious. If you want to create a 3D model of a house as quickly as possible, you use a laser range finder as a replacement for a measuring tape. Then you want to input that data into your modeling software as quickly as possible. That means it’s easiest to have your modeling software running on a mobile Raspberry Pi and your laser range finder connected directly to your Raspberry Pi. So, how do we do this?

How do laser measuring tapes work? How do you know you are getting the right thing? First of all, there are two main types of laser measuring tape. One is the phase shift type, that sends out a pulsing pattern with a multitude of wave frequencies and checks the return signal for interference levels against the original signal. The distance is solved using the phase shift of the various frequencies. The other method is the time-of-flight method. This uses clever techniques such as a lock-in amplifier and super-resolution to get a higher timer resolution, so reasonably precise measurements can be made. Finally, some really cheap devices are not a laser measuring tape at all, but actually just a sonar range finder that use a laser beam to help you aim. Also, some devices are simply just infrared near proximity sensors. Don’t go with those if you are trying to replicate an aluminum measuring tape. Also, of course, laser tape measures have a distance limit, and very long tape measures compromise on precision.

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Error measurements and classification in house logs

quorten

2018-10-12

Categories: home-network   personal-finance  
Tags: home-network   personal-finance  

So, after working with “house logs for dummies” for a little while, what became apparent is that I need to have a more advanced understanding of data and sensors. So, first of all, let’s review some of the very early sensor theory that was based off of early military radar system reporting. It’s a chart with only four cells.

+----------+----------+
|  False   |  True    |
| positive | positive |
+----------+----------+
|  False   |  True    |
| negative | negative |
+----------+----------+

As slick as this may seem, and as applicable as it is to radar reporting, it is an over-simplified sensor model for house logs for dummies. First of all, let’s describe some sensor phenomenon as observed in the house logs for dummies system:

  • Under-reporting is the norm. If you’re wondering why something apparently hasn’t happened, it’s probably due to under-reporting in the underlying system.

  • Sometimes there will be a report, but the specific data details of the report are entered incorrectly by mistake. In this case, the person who entered the incorrect data retains memory of what the correct action should be, and it is possible to prompt them at a later date for the correct data, provided that the date isn’t too late.

  • There is never a “false positive,” i.e. a report of an event when nothing actually happened. Indeed, this is perhaps the most significant difference from the radar system reporting.

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How to use oVirt for virtualization like VMware ESXi/vSphere

quorten

2018-10-10

Categories: random-software  
Tags: random-software  

Nowadays, Red Hat is further advancing its virtualization solutions to be more competitive with some offerings that have been coming from VMware such as ESXi and vCenter Server Appliance (VCSA). The general architecture of such VMware offerings is as follows:

  • Each host machine runs ESXi, which is basically a virtualization hypervisor operating system.

  • A vCenter Server Appliance is connected to multiple ESXi host machines. The VCSA can then be used to manage all of ESXi host machines the as a cluster. The vCenter Server Appliance also provides a web user interface to the management features and exposes a network API that can be controlled by other programs.

  • There are tons of wrapper libraries in different programming languages designed to expose a programmer-friendly interface to the network API exposed by the vCenter Server Appliance.

In abstract, you could argue that this high-level architecture is sound. However, there are very, very, many specific implemenation details that I don’t like about the real-world instantiation of the VMware ESXi and VCSA architecture. Nevertheless, Red Hat’s new virtualization solutions are designed to mimick in as many ways as possible, mainly as a means to look more appealing to existing users that have existing software code bases programmed up against the VMware APIs.

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Sinking garage foundation treatment, insulated slab, and more links from Mr. Money website

quorten

2018-10-09

Categories: home-network   important   personal-finance  
Tags: home-network   important   personal-finance  

Is it possible to improve a sinking garage foundation without rebuilding the entire garage? Yes, it is possible. Still, the answer is the same as it was before. Typical house garage foundations are considered small structures, so “jacking” (sand jacking, mud-jacking, slab-jacking) is the preferred method for treatment. The alternative that you were thinking of, piering, is typically only used on larger commercial buildings, schools, etc. There is also a list of things to look for that are major foundation warning signs, such as diagonal cracks.

Important! Another note on garage and basement floors. Do you want a heated garage? If so, you should design your garage floor to be an insulated concrete slab, otherwise without a thermal break separating the ground from the soil, that will just be a place to suck heat out to the frigid exterior.

20181009/DuckDuckGo improve garage foundation without rebuilding
20181009/https://www.concretenetwork.com/concrete/foundation_repair/
20181009/http://starcraftcustombuilders.com/garage.htm

This is another interesting article about someone building their own garage. Especially useful is the mention of their thermal treatment of the floor.

20181009/https://www.mrmoneymustache.com/2017/01/24/diy-studio-building/

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Mr. Money website about personal finance

quorten

2018-10-09

Categories: personal-finance  
Tags: personal-finance  

Oh, really interesting article here.

20181008/https://www.mrmoneymustache.com/2018/10/05/the-fire-movement/
20181008/https://www.mrmoneymustache.com/about/

Okay, okay, let’s back up. What is “FIRE” thing that is being talked about? It is an acronym: Financial Independence, Retire Early. “Financial Independence” implies this: you have enough assets and investments to fund your living expenses, therefore you do not need to be employed and working for someone else to keep paying for your living expenses. The “retire early” part? Well, that is a choice made by one of the proponents of the movement, i.e. the author of the aforementioned website, but it is not required, also as explained on the website.

So, how did the author of the site get this rich? Well, the equation was surprisingly simple, in their words. They were just employed in typical American middle class tech jobs, in from engineering and computer science degrees. However, they only spent what they needed to meet their living expenses, and was overall quite frugal in their spending compared to their peers. Also, they had some investments (in stock market index funds) and two rental homes. Then one day, to their surprise, they looked at their available earnings, and realized they didn’t need to keep working as they were to pay for their future life expenses. So that’s how they got started, simply put.

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