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Résumé for Jakob
Christensen
Email: info@jakobchr.com
Experience


Guest
Researcher
Informatics and Mathematical
Modeling, Lyngby, Denmark (20022004)
Objectoriented analysis,
design and implementation in C++:
Completed the TRACMIX++ code with more than
50,000 lines of highly efficient C++ code for the numerical simulation
of flow in large enclosures. Used the Portland Group Compiler suite
under Linux. Completed TRACMIX++ OO design using: Use
Cases, CRC Cards, Class and Interaction Diagrams in UML (used ArgoUML
under Linux); Utilized OO design patterns frequently;
Implemented TRACMIX++ with heavy use of STL, inheritance, templates,
namespaces; Developed library of 1D functional classes
(hierarchy) supporting a variety of mathematical operations; Developed a design for solvers of nonlinear
equations using the strategy design pattern (secant method, Pegasus
method); Invented design pattern for classes of
numerical methods with different order (=accuracy); Invented design pattern for a completely
flexible database storing physical properties of any number of
fluids; Developed flexible class for storing
frequently used physical properties for optimal computational
speed; Developed a template based general 1D
computational grid with general 1D grid elements; Developed library of classes (hierarchy)
describing flow source models; Developed class hierarchy describing
different flow paths; MATLAB output generator: Developed a design
for outputting any C++ class to a MATLAB .matfile (ideal for doing
post processing in MATLAB)
Mathematical/Numerical
Modeling:
Derived a set of coupled nonlinear PDEs
describing fluid motion in large enclosures and Derived discrete equations using a control
volume approach for obtaining numerical solutions and Derived the truncation errors associated with
the discretization. Constructed discrete mathematical models for
diffusion of heat and mass in a medium with discontinuities and Derived the error associated with this
discrete model; Derived a mathematical model describing the
pressure changes in a large enclosure and Devised an algorithm suited for computing the
pressure change; Developed strategies for management of the
large enclosure computational grid to ensure minimal computational cost
with optimal accuracy
Computer simulations:
Ran computer simulations to verify/validate
TRACMIX++. Compared simulations to experimental data



Research
Associate
ThermalHydraulics Group,
Berkeley, California, USA (19972001)
TRACMIX++: Initial design of mathematical
model, code design and implementation
Ran the MonteCarlo code MCNP for nuclear
reactor criticality studies
MATLAB code development:
Developed suite of mscripts with about 5,000
lines of MATLAB code for simulating simpler flows in a large enclosure
including scripts for postprocessing; Developed mscripts for solving the transient
1D multigroup neutron diffusion equation (a set of coupled PDEs,
neutron kinetics including delayed neutrons) and Solved the PDEs using the Method of Lines
Maple code development:
Developed Maple codes for obtaining
analytical solutions to the PDEs describing transient heat and mass
diffusion
Safety Assessment:
Reviewed deterministic design basis and
severe accident scenarios of General Electric's SBWR nuclear reactor



Graduate
Student Researcher
Institute of Mathematical
Modeling. Lyngby, Denmark (19941995)
Mathematical/Numerical
Modeling:
Developed 1D steadystate multigroup
neutron diffusion mathematical model (G coupled nonlinear ODEs) with
void and temperature reactivity feedback and Derived discrete equations using finite
differences resulting in a blocktridiagonal generalized eigenvalue
problem and Derived truncation errors associated with the
discretization and verified the order using numerical simulations;
Developed mathematical model of the primary
flow look of a nuclear reactor (BWR) for the calculation of the natural
circulation flow rate and Solved the resulting nonlinear equation
numerically using the Pegasus Method; Developed mathematical flow model (one
nonlinear ODE coupled to two nonlinear equations) for the core region
of a nuclear reactor (BWR) (1D partial equilibrium subcooled SP,
subcooled TP, bulk boiling); Developed mathematical model (one nonlinear
ODE) for heat flow (diffusion and convection) for water cooled
cylindrical nuclear fuel pins and Derived semianalytical solution;
Derived truncation errors associated with the
discretization and verified the order using numerical experiments
Computer
simulations:
Performed design study (ran computer
simulations) for a natural circulation nuclear reactor
(BWR); Calculated homogenized neutron crosssections
using the collision probability code, cccmo
C code
development:
Completed one large project with more than
20,000 lines of source code for the numerical simulation of a natural
circulation nuclear reactor (BWR); Used Borland C and GNU C compiler suites
under Windows; Developed numerical subroutines solving
generalized eigenvalue problems using the power and inverse power
method; Developed numerical subroutines for direct
solution of block tridiagonal systems of linear equations;
Implemented library of routines for solving
nonlinear equations (Pegasus method, fixed point iteration, secant
method); Developed MATLAB output generator for output
of C data structures in .matfile format; Developed routines for cubic spline
interpolation (data fitting)
MATLAB code
development:
Developed mscripts for solving generalized eigenvalue
problems using the power and inverse power method; Developed suite of mscripts for simulating
the natural circulation flow rate in a nuclear reactor (BWR)

Skills


Management skills: Mentoring; Reviewed/assessed
research; Coauthored annual progress
reports; Wrote technical proposals
including budgets etc; Gave technical presentations at
conferences, symposia and meetings



Languages: Fluent: Danish,
English; Comprehensive:
German; Beginnings: Spanish



Operating
Systems: Linux, Windows (dos, 3.11, 95, 98, NT, 2000,
XP), HPUX, Solaris



Key
software experience: MATLAB, Portland Group Compiler
Suite, GNU C/C++ Compiler Suite, Borland C/C++ Compiler Suite, Maple,
MCNP (MonteCarlo code), MS Office Suite, ArgoUML, Emacs, Xfig



OOP/C++:
Skilled in producing highly efficient C++
code; Familiar with the use of the C++ Standard and
the UML Specification



Python
code development: Developed Linux script for printing a
file identification header for PostScript files



Web
design: Designed and implemented my web site
www.jakobchr.com



Linux
system administration: Installed network print server
facilities, set up local networks, recompiled Linux kernels, installed
and upgraded software, hardware and drivers. Have 7+ years of experience



LaTeX
and Emacs: Developed extensive macro library for
scientific typesetting in LaTeX; Developed macros for extensive text and data
manipulation in Emacs

Education/ Awards


PhD, Department of Nuclear Engineering, University
of California, Berkeley (2003)
MS, Electrical Engineering, Technical University of
Denmark (1995)
Received various fellowships at UC Berkeley and
awards from private foundations (19972001)

Activities


Professional Member of SIAM, Society for
Industrial and Applied
Mathematics
Professional Member of ACM, The Association
of Computing
Machinery

Revision 2.0, Copyright © 19992004 Jakob
Christensen
http://www.JakobCHR.com
EMail: webmaster@JakobCHR.com

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