Archive for category My job

BIMing openings in the historical buildings: first try

Parametric opening with per instance adjustable inset depth, left and right tapers both on the inside and outside.

Recent issues with SSH

userauth_pubkey: signature algorithm ssh-rsa not in PubkeyAcceptedAlgorithms [preauth]

And it will not allow to connect using older, SSH-1 keys.

The temporary solution is to add

PubkeyAcceptedKeyTypes +ssh-rsa

to the /etc/ssh/sshd_config and restart the SSH daemon. Well, it’s advisable not to use weaker keys for a long time.

Thanks to the Archlinux forum for the info

Tags: ,

Formulas for Daylight Factor calculation

In architecture, a Daylight Factor (DF) is the ratio of the light level inside a structure to the light level outside the structure. The only problem – you must know both the illumination level on the inside, on the working plane and simultaneous outdoor illuminance on a horizontal plane from a unobstructed hemisphere of overcast sky.

A Daylight factor can be expressed as an average, using experimental formulas. Here are some of them:

Read the rest of this entry »

Removing exclamation mark for Windows drive

In some cases the yellow explamation mark can be “stuck” for a drive. There are some possibilities here:

  • low disc space;
  • Bitlocker

The most reccomended way to remove the exclamation mark is to turn Bitlocker protection on and off.

In the case you don’t want the Bitlocker, you can turn it off for a drive using command line, as described here.

Run the command prompt as adminstrator and enter the command:

manage-bde C: -off

You can check the drive status with

manage-bde -status

You will get something like this in response:

BitLocker Drive Encryption: Configuration Tool version 10.0.19041
Copyright (C) 2013 Microsoft Corporation. All rights reserved.
Disk volumes that can be protected with
BitLocker Drive Encryption:
Volume C: [Sys]
[OS Volume]
Size:                 953,24 GB
BitLocker Version:    2.0
Conversion Status:    Decryption in Progress
Percentage Encrypted: 25,1%
Encryption Method:    XTS-AES 128
Protection Status:    Protection Off
Lock Status:          Unlocked
Identification Field: Unknown
Key Protectors:
    External Key
    Numerical Password

What is the size of a letter box?

The EN 13724:2002 “Postal services – Apertures of private letter boxes and letter plates – Requirements and test methods”, European standard for letterboxes specify that:

  • an envelope of C4 (229 mm × 324 mm) size must be deliverable without bending or damage;
  • the internal volume must able to hold at least a 40 mm high bundle of envelopes;
  • the height of an aperture is 30–35 mm;
  • the width of the aperture is either 230–280 mm (for C4 width) or 325–400 mm (for C4 height);
  • the mounting height of the aperture should be between 0,7 and 1,7 m.

Hacking LSS Chronolux

The “required insolation’ sector is added to support in-model decision on the limiting volumes and conditions.

This is not a public software, so please contact the author of the LSS Arch Tools for more questions.

Tags: ,

OpenSSL certificate generation

You must hae the CA configured properly, this no not the scope of this post.

For self-signed certificate

The self-signed certficate is in the <hostname>.crt, the private key is in the <hostname>.key

openssl req -x509 -newkey rsa:4096 -keyout <hostname>.key -out <hostname>.crt -days 365

For CSR (Client Certificate Request)

The request is in the <hostname>.csr, the private key is in the <hostname>.key.

-nodes option will turn off the password request, which is a Bad Idea for personal certificates and is sometimes used for server sertificates.

openssl req -newkey rsa:4096 -sha256 -nodes -out <hostname>.csr -outform PEM

mv mv privkey.pem <hostname>.pem

To generate a DH key

Make sure to adjust the Apache configuration accordingly, and

sudo openssl dhparam -out /etc/ssl/certs/dhparam.pem 2048

To sign a CSR

The request is in the <hostname>.csr, the signed certificates is in the <hostname>.crt.

openssl ca -policy signing_policy -extensions signing_req -out <hostname>.crt -infiles <hostname>.csr

To verify a certificate or request

The request is in the <hostname>.csr, the certificates is in the <hostname>.crt.

openssl x509 -in <hostname>.crt -text -noout
openssl req -text -noout -verify -in <hostname>.csr

Tags: ,

SSL, Postfix and IMAP

When setting up authenticated SMTP service, be sure your IMAP server is accessible. The reason for this is Postfix will check the username using SASLauth daemon. And SASLauth damon uses “rimap” method for checking the username. Rimap is “remote IMAP”, and it tries to log into the configured IMAP service, which by default is defined as ‘localhost’.

Read the rest of this entry »

Tags: , ,

Video distribution in the classroom

We have a computer room in our local university, ind it’s quite bussy. The main problem it became (this is another story) too long to be usable and there was a strong demand for the screencast view right on the student’s workplace. Yes we do use beamers, but the view was too small to dead the text on the screen.

And so the project was born. There is single seat where the view originates and multiple locations where it should be visible. The system must be easily expandable and upgradeable, no vendor lock-ins. All the points in the systems should be easily adjustable and replaceable.

Read the rest of this entry »

Tags: , , ,

Small problem with CFD simulations

Just a tiny hole in the mesh may create a great mess.

The initial wind speed is 10 m/s, laminar aiflow. And the result is small F15+ class tornado int he Fujita scale.