The 2nd Monitor

nhgrif

22:01

New post: So, what's this blog all about? http://importblogkit.com/2015/03/so-whats-this-blog-all-about/

Tweeted by importBlogKit on March 19, 2015 at 9:59 PM

Phrancis

@nhgrif I really like the colors you chose for the links!

nhgrif

It's all based on Xcode's Midnight theme. ;)

Phrancis

Hah nice!

TTQW FINALLY.

Simon André Forsberg

22:16

@Mat'sMug let's just say "enough" Simon's ;)

@Phrancis try { work(); } finally { ttqw(); }

Duga

"Follow your heart though ;)" at least until the programming lead tells you to start doing it in code review. — the Tin Man 16 secs ago

Captain Obvious

0

Q: Simple Batch Templating Utility in Python

I would like to present for review my (much) revised batch templating utility which had it's humble beginnings here in a previous post. As I mentioned there, this program is my entry into python programming. I am trying to grow the simple script from my previous post into a more robust utility....

nhgrif

How come beginner still isn't dead?

RubberDuck

Because it helps me not be a complete ass...

nhgrif

Really?

RubberDuck

22:26

Yeah. Really. It makes it much easier for me to tolerate awful code.

2

nhgrif

Isn't awful, working code exactly what we're looking for here?

Stack Exchange

0

Q: Create structs tag? Or burn classes tag?

Are we okay with classes? If so, how come there's not a structs? Would it be appropriate? Should I create structs, or would it be better to burn classes?

discussion tags

nhgrif

Isn't that the pinnacle of being on-topic on Code Review?

Captain Obvious

0

Q: Comapring cvblobslib matlab

I'm trying to implement this code from matlab: % Calculate each separated object area cDist=regionprops(bwImg, 'Area'); cDist=[cDist.Area]; % Label each object [bwImgLabeled, ~]=bwlabel(bwImg); % Calculate min and max object size based on assumptions on the color % checker size maxLabelSize = ...

matlab opencv

Mehrad

22:42

Morning champs

rolfl

Hey @Mehrad

Mehrad

@rolfl you were the topic on yesterday's R&D meeting :)

rolfl

I stayed up way late looking in to alternatives too...

Mehrad

my mates recommended this however, I doubt that it'll be in your price range :D

rolfl

did you all solve it for me?

Mehrad

22:46

campbellsci.com/cs450

apparently we already did and made this little sensor.

the cable you see is an evacuated cable which carries comms and also the evac pipe

The output is for SDI-12 so you could read it with any device capable of reading the protocol

nhgrif

Oh, hey... I moved into top 10% for swift on Stack Overflow. Also... I'm top 10% java...

Mehrad

and what I always find interesting is that, our company was one of 2 or 3 companies involved creating the SDI-12 protocol :)

rolfl

@Mehrad Yeah, it's expensive.... if I have to request a quote ;-)

I have one of these: meas-spec.com/downloads/85C.pdf

it's a compensated part, should not need complicated calibration from me.

Mehrad

You're in US right?

rolfl

canada

Mehrad

22:57

We have a Canadian branch as well

rolfl

My one plan is to submerge just a "bladder" to the bottom of the well, and it should carry the pressure in a tube to the surface.

Mehrad

sure I can arrange a quote for you. (I mean it won't hurt to know the price, right) if it works for you all you need is to dunk in and forget it for the next 50 years :)

rolfl

You know what? Sure. Yes please. a quote ... ;-)

Mehrad

@rolfl we discussed 3 different methods yesterday. Gauge, absolute and ultrasonic but honestly your approach is the most common and cost effect one which lead to developing CS450 as well

rolfl

Did you consider capacitative?

Mehrad

22:59

This sensor does all you really planning to do so you're right on track

piezoresistive is the way to go. They perfectly fit in this plan

rolfl

or, how about me considering a float on a pulley over a rotary encoder?

I thought long and hard about that one .... ;-)

Mehrad

again you could go for an absolute measurement however the second sensor you would need on the master device for the bP measurement

sure you did your homework cuz the moment I spit out the question all I heard was your solution or Ultrasonic which the sensor we have for that one cost 20 grand :)

Captain Obvious

0

Q: simple binary heap in C#

I've written a simple binary heap in C# and I want to know if it has any problems or I can make it better. public enum HeapType { MinHeap, MaxHeap } public class Heap<T> where T : IComparable<T> { List<T> items; public HeapType MinOrMax { get; private set; } public T Root ...

c# heap

0

Q: Knuth's Word Wrap Algorithm in Haskell

I put together a Haskell function for Knuth's word wrap algorithm. I've already been told that there are certain aspects of my style that are not very agreeable (e.g. lack of comments and type declarations). However, I'd like to get some opinions on where I might be able to improve the performa...

performance haskell

rolfl

Yeah. What stumped me is that the cost of the pressure transducers is so high.... and then the encasements is so high too. At this point, though, a fait-acompli is actually a good option.

Mehrad

if the surface is freezing the float is out of the scope :) and also the cheap ultrasonic which mounts on the top and measures the depth. Submersibles which measure from the bottom are super expensive.

rolfl

23:04

@Mehrad - just FYI, submerging the transducer is my plan B (for cost/reliability of a hobby solution).

I would have thought that the submerged pressure-bladder is the best option.

Mehrad

Whats the A

rolfl

consider a cylinder with, say, a 1 liter bladder inside it.

it is 'inflated' but not pressured at the surface.

the bladder is attached to a tube, which is connected to the transsducer which lives in a 'box' above water level.

as the bladder gets deeper, the pressure of the water will automatically be applied to the transducer (minus whatever atmospheric differences there are in the height).

your limit is the relative volume of the bladder vs the volume inside the tube.

Mehrad

and lots of calibration :)

rolfl

Now, that's the point, what callibration is needed?

what's the difference in atmospheric pressure between altitude X and altitude X+10m in air?

almost nothing.

but in water, it's 14.6psi

Mehrad

You gotta map the pressure you read to the depth of water which is effected by the pressure + temp

rolfl

23:08

no, it's not... at least, not significantly (like, less than 0.001% I would guess).

the only difference between the location of the transducer (whether it's at the top, or the bottom), is whether the atmospheric pressure of the vent tube (if it's at the bottom) is added to the guage pressure, or subtracted from, if it's at the top.

Mehrad

PV = nRT and since your sensor isn't in the same place which your bladder is then lots of uncertainty would happen. at least on the papaer

emm not really. Your sensor measures whatever you connected to it and the pipe radius when it comes to proportions cancels out those parasitics

nhgrif

This is a really strange conversation.

rolfl

that's my thinking.... unless the water pressure at depthX changes when I put a bladder there... just so long as the bladder does not leak, the air pressure will be 'constant' in all parts of the bladder/tube.

Mehrad

The biggest problem is this whole thins isn't really the pressure reading but dealing with the evacuated pipe. factors such as condensation forming and sealing the unit. If the sealing is good and the unit is dessicated properly you'll be laughing

rolfl

since the water pressure completely overwhelms the atmospheric pressure over water-depth 10meters, the atmospheric differences can be ignored.

Jeroen Vannevel

23:13

Now this I don't like. If you return BadRequest(ModelState) it doesn't create a BadRequestResult or a BadRequestErrorMessageResult but rather a InvalidModelStateResult.. As if that is something special

Mehrad

@nhgrif :D

nhgrif

What are you talking about @JeroenVannevel

Jeroen Vannevel

@nhgrif asp.net web api 2

Mehrad

@rolfl easily. all you need to do is some initial calibration

rolfl

the dessication is secondary, with, say, a 'camel-bak' water bladder on some regular house plumbing pipe, there is very little possibility of the condensation causing a problem.

leak is the only problem.

Jeroen Vannevel

23:15

More specifically this line of code: github.com/Vannevelj/Moviepicker/blob/master/MoviePicker/WebApi/…

rolfl

bizarrely, freezing is never a problem, even in -50-so temps.

Mehrad

I assume you know the depth and the height of water when you're dunking the sensor you should get pretty good results in the range of (total estimate) +-5 cm

and that doesn't matter cuz you want to be in the safe side and not burn the pump so you can cut it way earlier

rolfl

I can tolerate an absolute error of about 30-cm .... but relative errors are more significant.

I need an absolute warning of "the well is almost dry", and that level can be "close".

nhgrif

The only thing worse than TODO: is a TODO: that's a question.

rolfl

the more significant one is I need the precision to be able to tell whether the well has lost or gained a cm....

So, I can be a bit vague on the absolute depth, but need accuracy on the delta's

Mehrad

23:20

that's right. knowing the parameter of the physical size and depth can fix that problem for you. Calibration is the sophisticated way of saying trial and error when you have references :) of course you can't drain the well dry to have your reference on the other side but you can come close :)

rolfl

Well, it's easy, I just wait for the bladder to submerge say, 6 inches, then measure the pressure there, and save that away as "warning level". Then I submerge it the rest of the way to the bottom,.

That way I have nothing electrical submerged.....

I "think" it will work, all I need to do is build it.

Mehrad

The environmental organization we deal with want to pick up on numbers which can prove or disprove global warming or seasonal change and that's what makes the job hard. You are in the sweet spot of measurement in that term.

@rolfl Yep. mapping is the way to go :)

rolfl

A brick, bladder, and 50' of hose, a pressure transducer, no leaks, and you can measure anything reasonable.

Need more than... 30 meters of water, and you will need something better, or a bigger bladder.

If the water is not "flowing", then you can have relatively simple systems.

nhgrif

I don't even know what kind of bomb you guys are building.

rolfl

@nhgrif - I just want to keep my father-in-law warm in winter, basically, because that makes my wife happy ;-)

and, I get to play with a soldering iron, and a raspberry pi.

And.... a wheatstone bridge.

Mehrad

23:26

happy wife happy life :)

what's the depth for each ?

nhgrif

They don't sell space heaters in Canada? That's weird.

Mehrad

that's really odd for a cold place like Canada :)

here that we have lowest 26 and highest 40 degree C over the year a little bit more reasonable :D

rolfl

@Mehrad the "dug" well has 11 "tiles" of 30-inches each.

330 inches in total....

but I have never seen the water closer than 3-tiles from the top.

Mehrad

let me give you some brands for sealing up your canister

rolfl

hammond does an IP66 for $8

Mehrad

23:29

Oh... now you're not talking metric :)

rolfl

I like doing a beagle.

Jeroen Vannevel

You're canadian.. Can't he just go outside and wrestle a moose for a few minutes?

Mehrad

IP66 is splash proof :D

rolfl

which is fine if it's at the top of the well, right?

Mehrad

Oh, right

rolfl

23:31

digikey.ca/product-detail/en/1550Q/HM1204-ND/2211554

That box, has a gasket available which makes it IP68... but not really.....

digikey.ca/product-detail/en/1550QSGASKET/1550QSGASKET-ND/…

Mehrad

but your system should be hermetically sealed in this arrangement or you keep losing pressure until your bladder is flat

rolfl

True.... that's true.

Mehrad

so you would go with sealing the whole box and using a hermetically sealed glands and connectors or making a little reference in the box sealed

nhgrif

I was about to coin the term "magic strings", but I see it's already in use, with a different meaning...

rolfl

I was thinking of attaching transducer on the inside of the box, with the sensor sticking outside, and the tube from the bladder attached to that, on the outside... thus, keeping only the electrics inside ;-)

So.... complicated.

Mehrad

23:35

emmm... not the best design but why not. You don't have customers using it. you can put it where ever you want to and be super delicate with it

rolfl

Well, I will not UPS it to him, that's for sure ;-)

the logistics of getting clean power to the well, and of getting the signal back, and doing the measurements close to the transducer, those are going to be my real problems.

A cat-5 cable with a couple of conductors for power, and a couple for some serial protocol, and a trigger, say, every second, will charge a 'local' super-cap, then regulate that to a constant current source of 1.5ma, and a clean supply for a 12/14 bit ADC.... then a way to transmit the reading back....

nhgrif

0

A: Store CMTimeRange into Core Data

Objective-C doesn't have namespaces. As such, we need to be much more careful with our class names. The common way for dealing with this problem in Objective-C is to come up with a 2 or 3 letter prefix to put in front of all of your classes. Apple does this with their classes. NS for NeXTSTE...

rolfl

Well, Mehrad, it's been nice rubberducking this with you....

and great to have my "plan" ratified/approved ;-)

thanks

Mehrad

:) sure do. I will ask for some sensor prices for you from our Canadian branch as well

guess you told me the depth somewhere if I can find

rolfl

It's nicely just less than 33feet, or 10 meters.

1 atmosphere.

Mehrad

23:41

great.

rolfl

14.5psi ...

Mehrad

let me know who it goes on the process and I might be able to give you a hand (or at least brainstorm of some sort)

@rolfl this diagram will remind me what you wanna do :)

rolfl

That's it.

That's a crap, early version, but it will help you rememver too ;-)

It does a lot of things wrong......

but you can have a giggle.

and an early version of the "submersible" option....

nhgrif

Magic (programming)

In the context of computer programming, magic is an informal term for abstraction - it is used to describe code that handles complex tasks while hiding that complexity to present a simple interface. The term is somewhat tongue-in-cheek and carries bad connotations, implying that the true behavior of the code is not immediately apparent. For example, Perl's polymorphic typing and closure mechanisms are often called "magic". The term implies that the hidden complexity is at least in principle understandable, in contrast to black magic and deep magic, which describe arcane techniques that are ...

> The term cargo cult, as an idiom, originally referred to aboriginal religions that grew up in the South Pacific after World War II. The practices of these groups centered on building elaborate mock-ups of airplanes and military landing strips in the hope of summoning the god-like airplanes that had brought marvelous cargo during the war.

Hosch250

23:56

@nhgrif Those are peculiar, aren't they?

Duga

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