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The (Web) Home of Jakob Christensen

....to my permanent cyberhouse.

These pages reflect what I consider important in life.
This is of course a highly subjective subject; now you have been warned!

Jakob Christensen

  Jakob Christensen, 2003

Important aspects of life
  1. Health
  2. Family
  3. Work
  4. Internationalism

Other points of interest


Optimal health is a prerequisite for every other aspect of life. I believe optimal health can only be achieved by
  • Optimizing ones diet. The fundamental principle for choosing dietary items can be stated as (I believe): non-processed, with the absence of technology.
  • Being critical to exposure to chemicals of every kind. The bodies of today are exposed to a myriad of chemicals entering the body through the mouth, the lungs, the skin or through direct contact (dental fillings and other foreign materials introduced directly into the body through surgery). My advice: Be careful and try to limit voluntary exposures.
  • Stimulate the cells of the body. Both stimulation of the mind the body are important. 1-1.5 hrs of daily physical activity is ideal. A good intensity level is one where the body starts to get a good heat-up with sweating. Personally, I prefer road cycling. Ideally one should include a long duration exercise once a week (or twice if time permits). A duration of 4-5 hrs is ideal as this really stimulates a lot of cells in the body. Tip: Always KNOW your body when doing physical exercise. It tells you a lot if you care to listen.


What is life without a lifetime companion that you love?
        .................Emptier, I believe.

What is life without wonderful children? 
        ...........Non-existent. Just look at the disappointing birth rate statistics for the developed world.


Work in its most general form is important for everybody whether it is hunting the Argentinian prairie for food, designing a new high performance nuclear reactor or trying out the newest financial derivatives risk models.
Combined with #2 it gives life meaning, a purpose. Without this purpose life become rather meaningless.
Furthermore, work has the potential to stimulate your brain in a way no other activity does.
For the type of work that I am interesting in please Click Here.


Internationalism also has the potential of stimulating your brain in a way no other activity does.
People of today are very fortunate. With the advent of the Internet it is extremely easy to get to know people from other cultures on the Planet and maintain contact wherever you are.
All it really takes is openness, open-mindedness and a little effort.
And it may change your perspective and life in a profound way; if you give it a chance.

Work related interests

To sum up, my work related interests have always been centered around

Building mathematical models, applying numerical analysis and using computer programming to simulate complex non-linear dynamical systems.

I have extensive experience and knowledge solving systems of non-linear PDEs numerically, both in steady-state and unsteady cases.
Direct simulation of dynamical systems is a key interest. For this reason (and the fact that I am an Nuclear and Electrical Engineer) I am also interested in control engineering and signal processing and analysis.

Up till now my modeling and simulating efforts have been concentrated on those of importance for nuclear power reactors:

Reactor Physics (Neutronics):
The multi-group diffusion equation, both steady-state and unsteady state. These equations describe the distribution of neutronics in space, time and energy (more accurate descriptions of neutron transport based on the Boltzmann transport equation also take into account the angular neutron distribution). In steady-state this equation consists of G non-linear PDEs, where is the number of neutron energy groups. In the unsteady case these G PDEs are coupled to typically 6 PDEs describing the production of delayed neutrons.

Reactor core thermal-hydraulics:
Single- and two-phase fluid conservation equations. In the general unsteady case a set of 3 non-linear PDEs coupled to a number of algebraic equations (for void fraction, wall shear stress and sub-cooled boiling).

Large enclosure thermal-hydraulics:
1-D Fluid conservations for stratified multi-component flows consisting of I+2 coupled non-linear PDEs, where I is the number of fluid components. The equations are solved in the Lagrangian frame to accommodate the near-discontinuous flow field of the stratified fluid.

Financial Mathematics:
I am also interested in financial mathematical modeling, mostly financial derivatives pricing models.

Software development:
I have extensive knowledge, experience and interest in building large computer codes for simulation purposes.
I have built a complete coupled neutronics thermal-hydraulics model of a natural circulation BWR. To simulate reactor behavior with this model, I implemented a C code with more than 20,000 lines of well-commented and well-structured source code.
More recently I have done extensive modeling and simulation efforts addressing nuclear reactor containment responses. For this modeling effort, I have switched to C++ as my preferred programming language because of the clear advantages that object-oriented programming has to offer. The resulting C++ code has more than 50,000 lines of well-commented highly advanced C++ source code.
I spent a considerable effort applying state-of-the-art object-oriented analysis and design, including the use of Use Cases, CRC cards, and class interaction diagrams and class diagrams in UML. The resulting C++ code utilizes numerous design patterns both standard and new ones coined during the design phase of the project.

Professional affiliations

Society for Industrial and Applied Mathematics Professional Member of SIAM, Society for Industrial and Applied Mathematics. (www.siam.org)
The Association of Computing Machinery Professional Member of ACM, The Association of Computing Machinery. (www.acm.org)

Other interests

Road Cycling.

Sports medicine, physiology of training, advanced heart rate monitoring.

Pro audio Equipment (esp. Digital Recording (DAT)).

Ancient Hunter Gatherer Societies


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