Postings tagged with 'Links', listed in descending order by creation date. Last Postings shown.

Heat Pump System and Renewable Energy

(elkement. Last changed: 2015-11-07. Created: 2015-02-04. Tags: Postings, Blogging, Resources, Links, Engineering, Heat Pump. German Version.)

I blog about anything heat-pump-related, in particular about our system. In addition, I am interested in thermodynamics, heat pumps and heating systems in general - and their integration with the smart grid and related security concerns. These are my postings about our 'ice-storage-/solar-' powered system specifically and postings on closely related subjects like the power grid, renewable energy and sustainable living.

Hydraulic schema of our system

My Articles on IT Security, Monitoring, PKI.

(elkement. Last changed: 2015-11-07. Created: 2014-06-01. Tags: Postings, Blogging, Resources, Links, IT, Monitoring, PKI, Security, X.509, Cryptography. German Version.)

My lecture slides on PKI and security are a bit dated already, I add them for completeness though.

Articles on my blog are targeted to a broader audience - perhaps they are too 'philosophical' for security experts. See the complete list of postings below, after the image.

X.509 Certificate

Last link changed: Migration of classical CSP to CNG / KSP, and old but good MS overview on certificates for network authentication of devices.

PKI: Links and Resources

(elkement. Last changed: 2015-12-07. Created: 2014-03-04. Tags: Resources, Links, IT, PKI, Public Key Infrastructure, Security, X.509, Cryptography. German Version.)

This is my list of Links to white papers and the like that I have found useful (restarted 2014). It is not an attempt to create a balanced or educational list. I am adding what I need right now!

Comprehensive reviews of PKI issues

Analysis by Peter Gutmann who likes to throw rocks at PKI according to his bio:

Certificate validation

Request for Comments:

In Windows systems:

Cross-certification and hierachies

Certificate enrollment

Links for Microsoft's autoenrollment are provided in more MS-related sections

Weird, hacked, forged certificates

PKI planning

Somewhat Microsoft-centric:

Windows PKI: Features and management

After I started compiling my own list, I found this - I will keep picking some of the links and publish them to this page though:

Some of the features required to run a Microsoft PKI in a larger, corporate environment:

Windows PKI 2008 R2 versus 2012 R2 and upgrade of hash algorithms

New features in 2012! Note I started added some the detailed articles about specific features - NDES, templates - also to other sections. This section is for overviews covering many new features or cryptograpy / algorithms in particular.

New ways to leverage a TPM chip - key attestation by validation of an endorsement key. You could have used a TPM chip as a custom key store for the machine / SYSTEM in earlier versions of Windows (basically like a 'smartcard for machines) in case the vendor of the TPM chip or a vendor of crypto software provided a suitable CSP / CNG provider. Starting with Windows 8.1 as the end-entity's OS the CA (2012 R2) is able to check if the private key had really been stored to a TPM chip.

New algorithms:

  • Changing public key algorithm of a CA certificate - only the hash algorithm can be changed (for CNG providers), not the provider itself.
  • Upgrade Certification Authority to SHA256 - after the change of a registry key the CA signs anything with the new algorithm, including CRLs and its own CA certificate when renewed (Step-by-step-instructions).
    Attention - according to my experiences with 2008 R2 the registry value for hash values is case-sensitive. Good: The change of the hash algorithm can be reverted easily. Bad: This is a per-CA settings, so once the algorithm has been changed all certificates and CRLs issued by that CA are signed using the new algorithm.

Certificate and key stores

Windows client-side stores:


Using certificates for authentication

Native Active Directory logon:

Webserver-based mapping (no directory)

Apple iDevices, SAP, and other non-MS clients

  • In contrast to Windows'/AD's native logon via UPN string mapping SAP uses a 1:1 mapping of binary certificates to users:
    Single Sign-on mit SAP (part of a German book, assignment of the certificate is explained on pp.33)
  • Apple iPhones, 802.1x authentication against Active Directory using Windows RADIUS server (NPS)
    (promoted to blog post, summary kept here for traceability).
    • Properties of the certificate
      Subject CN: host/
      Subject Alternative Name
      Certificate Template (Windows Enterprise PKI): Copy the default template Workstation Authentication, Subject Name: Name as submitted with the Request.
    • Create the key, request and certificate on a dedicated enrollment machine and export key and certificates as PKCS#12 (PFX) file.
    • Create a shadow account in Active Directory
      ervicePrincipalNames: HOST/
    • According to my tests, the creation of an additional name mapping (as recommended here) is not required - SAN-DNS gets mapped onto dnsHostName in AD.

Network authentication of devices

  • Overview: Certificates for different services / protocols, like 802.1x or IPsec

PKI Applications

Started in 2014-10. Usual suspects as SMIME, EFS, 802.1x to be added as needed over time. See also the list of Technet Postings and the PKI FAQ.

Useful commands (in the Windows world)

Configuration parameters:

Emergency processes, for Windows.

  • Delete cached CRLs:
    certutil -setreg chain\ChainCacheResyncFiletime @now
    (Weitere Optionen siehe diesen MS-PKI-Team-Blogeintrag)
  • Start a CA even if the revocation check on its own certificate has failed - set this flag:
    certutil –setreg ca\CRLFlags +CRLF_REVCHECK_IGNORE_OFFLINE
  • Key Recovery:
    • Search for the archived keys of a specific user and create a batach script (CA admin permissions required)
      certutil –getkey domain\username >recovery-username.bat
      This script also contains the password of the p12 key file that will be created.
    • Run this batch file. This creates a single p12 file including all keys for this user. Pre-requisites: The user executing the script needs to have one Key Recovery Agent's certificates associated with each of the keys to be recovered in his/her store. In addition CA Admin permissions are required and this needs to be an admin cmd session.
    • The batch file does the following for every key found:
      certutil -getkey [SerialNumber] [encrypted blob]
      certutil -recoverykey [encrypted blob]
      A temporary p12 file is created from every blob; then all p12 files are merged using
      certutil -mergepfx and all temporary files are deleted.

PKI and smart metering

Requirements for a smart meter PKI in Germany:
Sicherheitsinfrastruktur für „smarte“ Versorgungsnetze

An example: Smart Meter mit PKI Sicherheit

X.509 Certificate

Physics Links

(elkement. Last changed: 2015-02-14. Created: 2012-03-10. Tags: Physics, Links, Resources)

Here I maintain a list of physics books, documents, blogs, and lectures I read / watch or that I have put on the (virtual) bedside table.

The collection is not some carefully crafted, balanced list - I am not searching for resources to add them here but I add what is interesting to me as a professional or a dilettante science blogger. I apologize for the mixture of German and English resources, and the structure is always work in progress.

This list had been formerly curated on my blog, on a page called Physics Books on the Bedside Table. I decided to migrate these links over here as in 2014 I had started to curate all my tech / science links on

Popular Science Books 'enthusiastic'

Popular Science Books 'critical' (Note: This is not 'Alternative science')

History of Science and Biographies of Physicists

Quantum Physics, Quantum (Field) Theory

  • Oersted Medal Lecture 2002: Reforming the Mathematical Language of Physics, as recommended here. Actually, this is about all of physics and how more powerful, concise, and elegant Geometrical Algebra would do away with concepts that just appear tacked on – as there is an underlying hidden structure. It is useful in classical physics but especially to understand the seemingly weird world of the complex wave function.
  • Lectures on Quantum Field Theory by David Tong. Videos of his lectures delivered at Perimeter Institute can be found here (different formats available). These lectures were my starting point for (re-)learning QFT having been exposed to mainly condensed-matter-related and non-relativistic quantum statistics and 'second quantization' 20 years ago.
  • Quantum Field Theory in a Nutshell, a concise textbook by Anthony Zee. David Tong highly recommends this book, saying tongue-in-cheek: He lies to you all the time, but in a good way. It is not an easy read because the presentation of the material is quite condensed. You have to fill a lot of intermediate steps in derivations. On the other hand this makes it a great book for serious self-study. It shows that Zee is a gifted writer of popular science books as well as his conceptual overviews are spot-on and very helpful for tackling the hard stuff.
  • I trust Graham Farmelo on this and put Stephen Weinberg's book on my To-read-list.
  • Student Friendly Quantum Fielf Theory by Robert D. Klauber. Klauber describes and writes out details in derivations, avoids all references to so-called trivial, obvious and easy steps, and he refers to his own learning QFT often. The book seems to have been written from the learner's perspective – he often anticipates those typical baffled student's questions and answers them before you dared to ask it. More praise in this post of mine.
  • A lecture on Quantum Field Theory in German, by Gerhard Soff. I like these lecture notes because topics are reviewed from different angles (such as: canonical quantization versus path integrals) and the derivations are done in detail for all the different options.
  • The Fun is Real. Blog author Warren Huelsnitz definitely meets his goal: to sort through the myths and misconceptions, and the excessive and misleading hype, associated with quantum physics.
  • An Island In Theoryspace – an awesome blog by Jaques Pienaar on physics (mainly of the quantum variety) and sometimes also on its interface with philosophy.

Quantum Computing and Quantum Cryptography

The first field that rekindled by excitement for physics in about 2003, having worked in IT already for some years.

  • A blog written by a physicist and IT consultant who tries to separate fact  from VC fiction and to predict what impact quantum computing will have on corporate IT.


Thermodynamics and statistical mechanics

Fascinating water, water vapor, and ice


Classics: Basics and fundamentals – books and blogs that cover all of physics

It is very interesting to compare Feynman's and Macke's books – they have been published at about the same time and might serve as good examples for both excellent, but different ways  to describe physics from scratch – 'American' versus 'German'.

  • A very detailed blog – – Physics Tutorials with lots of examples, introductions and the author's solutions to text book problems.
  • Scientific Finger Food: Sebastian Templ achieves his goal – quote from his About page: “I give my best to break it down into simple language. In doing so, I hope that I can serve you some pieces of physics, which I like to think of as being clear to me, in 'delicious and manageable bites' “.
  • Six volumes on physics, written by a physicist who works as an innovation manager. Probably the most professional hobby / moonlighting physics project I have come across.

Classical Physics

Classical (point particle) mechanics

Fluid dynamics

Infinite Loop: Theory and Practice Revisited. (2018-06-10 11:56:55)
I’ve unlocked a new achievement as a blogger, or a new milestone as a life-form. As a dinosaur telling the same old stories over and over again. I started drafting a blog post, as I always do since a while: …

Can the Efficiency Be Greater Than One? (2018-04-09 11:40:59)
This is one of the perennial top search terms for this blog. Anticlimactic answer: Yes, because input and output are determined also by economics, not only by physics. Often readers search for the efficiency of a refrigerator. Its efficiency, the …

Consequences of the Second Law of Thermodynamics (2018-03-03 11:43:25)
Why a Carnot process using a Van der Waals gas – or other fluid with uncommon equation of state – also runs at Carnot’s efficiency. Textbooks often refer to an ideal gas when introducing Carnot’s cycle – it’s easy to calculate heat …

The Heat Source Paradox (2018-01-19 10:23:13)
It is not a paradox – it is a straight-forward relation between a heat pump system’s key data: The lower a heat pump’s performance factor is, the smaller the source can be built. I would not write this post, hadn’t …

Things You Find in Your Hydraulic Schematic (2018-01-12 10:35:58)
Building an ice storage powered heat pump system is a DIY adventure – for a Leonardo da Vinci of plumbing, electrical engineering, carpentry, masonry, and computer technology. But that holistic approach is already demonstrated clearly in our hydraulic schematics. Actually, …

Cooling Potential (2017-12-13 12:43:38)
I had an interesting discussion about the cooling potential of our heat pump system – in a climate warmer than ours. Recently I’ve shown data for the past heating season, including also passive cooling performance: After the heating season, tank …

Simulating Life-Forms (2): Cooling Energy (2017-11-28 16:09:55)
I found this comprehensive research report: Energy Use in the Australian Residential Sector 1986–2020 (June 2008) (several PDFs for download, click the link Energy Use… to display them) There are many interesting results – and the level of detail is …

The Collector Size Paradox (2017-11-01 15:11:56)
Recently I presented the usual update of our system’s and measurement data documentation.The PDF document contains consolidated numbers for each year and month of operations: It is finally time to tackle the fundamental questions: What is the impact of the …

Data for the Heat Pump System: Heating Season 2016-2017 (2017-10-12 09:58:29)
I update the documentation of measurement data [PDF] about twice a year. This post is to provide a quick overview for the past season. The PDF also contains the technical configuration and sizing data. Based on typical questions from an …

Tinkering, Science, and (Not) Sharing It (2017-09-17 11:06:44)
I stumbled upon this research paper called PVC polyhedra: We describe how to construct a dodecahedron, tetrahedron, cube, and octahedron out of pvc pipes using standard fittings. … In particular, if we take a connector that takes three pipes each …

Simulations: Levels of Consciousness (2017-08-17 10:41:54)
In a recent post I showed these results of simulations for our heat pump system: I focused on the technical details – this post will be more philosophical. What is a ‘simulation’ – opposed to simplified calculations of monthly or …

Heat Transport: What I Wrote So Far. (2017-07-14 09:15:49)
Don’t worry, The Subversive Elkement will publish the usual silly summer posting soon! Now am just tying up loose ends. In the next months I will keep writing about heat transport: Detailed simulations versus maverick’s rules of thumb, numerical solutions …

Simulating Peak Ice (2017-05-02 08:43:17)
This year ice in the tank was finally melted between March 5 to March 10 – as ‘visual inspection’ showed. Level sensor Mr. Bubble was confused during the melting phase; thus it was an interesting exercise to compare simulations to …

Mr. Bubble Was Confused. A Cliffhanger. (2017-04-08 11:06:20)
This year we experienced a record-breaking January in Austria – the coldest since 30 years. Our heat pump system produced 14m3 of ice in the underground tank. The volume of ice is measured by Mr. Bubble, the winner of The …

Where to Find What? (2017-03-18 15:20:13)
I have confessed on this blog that I have Mr. Monk DVDs for a reason. We like to categorize, tag, painstakingly re-organize, and re-use. This is reflected in our Innovations in Agriculture … … as well as in my periodical …

Ice Storage Hierarchy of Needs (2017-02-22 17:30:10)
Data Kraken – the tentacled tangled pieces of software for data analysis – has a secret theoretical sibling, an older one: Before we built our heat source from a cellar, I developed numerical simulations of the future heat pump system. …

Earth, Air, Water, and Ice. (2017-02-05 11:48:33)
In my attempts at Ice Storage Heat Source popularization I have been facing one big challenge: How can you – succinctly, using pictures – answer questions like: How much energy does the collector harvest? or What’s the contribution of ground? …

Frozen Herbs and Latent Energy Storage (2017-01-20 13:48:10)
… having studied one subject, we immediately have a great deal of direct and precise knowledge … of another. —Richard Feynman Feynman referred to different phenomena that can be described by equations of the same appearance: Learning how to calculate …

My Data Kraken – a Shapeshifter (2016-12-22 10:53:56)
I wonder if Data Kraken is only used by German speakers who translate our hackneyed Datenkrake – is it a word like eigenvector? Anyway, I need this animal metaphor, despite this post is not about facebook or Google. It’s about …

And Now for Something Completely Different: Rotation Heat Pump! (2016-11-03 09:55:35)
Heat pumps for space heating are all very similar: Refrigerant evaporates, pressure is increased by a scroll compressor, refrigerant condenses, pressure is reduced in an expansion value. *yawn* The question is: Can a compression heat pump be built in a …

Same Procedure as Every Autumn: New Data for the Heat Pump System (2016-10-21 09:49:11)
October – time for updating documentation of the heat pump system again! Consolidated data are available in this PDF document. In the last season there were no special experiments – like last year’s Ice Storage Challenge or using the wood …

Re-Visiting Carnot’s Theorem (2016-09-18 10:09:51)
The proof by contradiction used in physics textbooks is one of those arguments that appear surprising, then self-evident, then deceptive in its simplicity. You – or maybe only: I – cannot resist turning it over and over in your head …

Hacking My Heat Pump – Part 2: Logging Energy Values (2016-08-24 09:52:12)
In the last post, I showed how to use Raspberry Pi as CAN bus logger – using a test bus connected to control unit UVR1611. Now I have connected it to my heat pump’s bus. Credits for software and instructions: …

Hacking My Heat Pump – Part 1: CAN Bus Testing with UVR1611 (2016-08-03 10:04:39)
In the old times, measuring data manually sometimes meant braving the elements: Now, nearly all measurements are automated: In order to calculate the seasonal performance factor of the heat pump system we have still used the ‘official’ energy reading provided …

Photovoltaic Generator and Heat Pump: Daily Power Generation and Consumption (2016-06-01 12:21:02)
You can generate electrical power at home but you cannot manufacture your own natural gas, oil, or wood. (I exempt the minority of people owning forestry). This is often an argument for the combination of heat pump and photovoltaic generator. …

Everything as a Service (2016-05-19 13:57:08)
Three years ago I found a research paper that proposed a combination of distributed computing and heating as a service: A cloud provider company like Google or Amazon would install computers in users’ homes – as black-boxes providing heat to …

Alien Energy (2016-04-15 17:03:12)
I am sure it protects us not only from lightning but also from alien attacks and EMP guns … So I wrote about our lightning protection, installed together with our photovoltaic generator. Now our PV generator is operational for 11 …

No, You Cannot ‘Power Your Home’ by One Hour of Cycling Daily (2016-02-07 15:45:30)
In the past days different versions of an article had popped up in my social media streams again and again – claiming that you could power your home for 24 hours by cycling for one hour. Regular readers know that …

Temperature Waves and Geothermal Energy (2016-01-22 11:04:48)
Nearly all of renewable energy exploited today is, in a sense, solar energy. Photovoltaic cells convert solar radiation into electricity, solar thermal collectors heat hot water. Plants need solar power for photosynthesis, for ‘creating biomass’. The motion of water and …

How Does It Work? (The Heat Pump System, That Is) (2016-01-07 11:13:05)
Over the holidays I stayed away from social media, read quantum physics textbooks instead, and The Chief Engineer and I mulled over the fundamental questions of life, the universe and everything. Such as: How to explain our heat pump system? …

Personal website of Elke Stangl, Zagersdorf, Austria, c/o punktwissen.
elkement [at] subversiv [dot] at.