# Academic

I am currently a Postdoctoral Research Associate at the University of Cambridge, working on the ASiMoV project,
working with Garth Wells and Chris Richardson. I am also a College Postdoctoral Associate at
Jesus College.

Prior to this, I was a PhD student at University College London (UCL) where I worked on boundary element methods under the supervision of Timo Betcke and Erik Burman.

### Bempp

During my PhD, I became heavily involved in developing Bempp, an open-source boundary element method library.

Bempp is primarily written in Python with a fast C++ computational core. Documentation can be found at bempp.com.

### Maxwell wave scattering

During my PhD, I did much work on boundary element methods for Maxwell wave scattering problems.
In Bempp, I implemented Buffa–Christiansen dual function spaces: these spaces are required when multiplying two operators together
which is necessary when applying Calderón preconditioning to the electric field integral equation (EFIE).

These spaces are also useful when stably discretising the magnetic (MFIE) and combined (CFIE) field integral equations.
This work is discussed in more detail in

*Software frameworks for integral equations in electromagnetic scattering based on Calderón identities*(2017).### Weak imposition of boundary conditions

During my PhD, I worked on a method of weakly imposing boundary conditions when using the boundary element method.
This method weakly imposes the boundary conditions by adding a penalty term to the full Calderón system, inspired by
Nitsche's method for finite element methods.

Due to the approximate double of the number of unknowns, this method is not competitive
for pure Dirichlet and Neumann problems, but for more complex boundary conditions—such as
Robin boundary conditions and mixed boundary conditions—it provides a much simpler formulation that is easier to implement.

We analysed this method for Laplace Dirichlet, Neumann and Robin problems in

*Boundary element methods with weakly imposed boundary conditions*(2019), and are currently working on an application of it to the Signorini problem.### FEM-BEM coupling

Early in my PhD, I worked on the coupling of the finite and boundary element methods.
For transmission problems involving wave travelling through a large or infinite medium and through a small inhomogeneous object,
the boundary element method is well suited to solving the problem outside the object while the finite element method is better suited
for solving the problem inside the object. Using the two methods for the two parts of the problem gives rise to FEM-BEM coupling.

A full list of my papers, conference talks, awards and nominations can be found below.

Research Associate, Department of Engineering, Cambridge |

PhD student, Department of Mathematics, UCL |

**2019**

#### Papers

T. Betcke, E. Burman & M. W. Scroggs. Boundary element methods with weakly imposed boundary conditions,

*SIAM Journal on Scientific Computing*41(3), A1357–A1384. [pdf, arΧiv, doi.org/10.1137/18M119625X]A. Kleanthous, T. Betcke, D. P. Hewett, M. W. Scroggs & A. J. Baran. Calderón preconditioning of PMCHWT boundary integral equations for scattering by multiple absorbing dielectric particles,

*Journal of Quantitative Spectroscopy and Radiative Transfer*224, 383–395. [pdf, arΧiv, doi.org/10.1016/j.jqsrt.2018.11.035]E. Burman, S. Frei & M. W. Scroggs. Weak imposition of Signorini boundary conditions on the boundary element method, submitted to

*SIAM Journal on Numerical Analysis*. [arΧiv]#### Awards & nominations

#### Conference talks

Weakly imposing boundary conditions on the boundary element method using a penalty method (Mafelap 2019)

#### Teaching

In 2018-19, I taught the Python part of taught MATH0011: Mathematical Methods 2. Notes for this course can be found at mscroggs.co.uk/0011.

**2018**

#### Papers

#### Conference talks

Solving integral equations for electromagnetic scattering using Bempp (poster) (PDESoft 2018)

Weak imposition of boundary conditions using a penalty method (IABEM 2018)

Weak imposition of boundary conditions using a penalty method (Söllerhaus Workshop on Fast Boundary Element Methods in Industrial Applications)

**2017**

#### Papers

M. W. Scroggs, T. Betcke, E. Burman, W. Śmigaj & E. van 't Wout. Software frameworks for integral equations in electromagnetic scattering based on Calderón identities,

*Computers & Mathematics with Applications*74(11), 2897–2914. [pdf, arΧiv, doi.org/10.1016/j.camwa.2017.07.049]#### Awards & nominations

#### Conference talks

Solving integral equations for electromagnetic scattering using BEM++ (Strathclyde 27th Biennial Numerical Analysis Conference)

Solving integral equations for electromagnetic scattering using BEM++ (Söllerhaus Workshop on Fast Boundary Element Methods in Industrial Applications)

**2016**

#### Awards & nominations

#### Conference talks

Solving Maxwell problems with BEM++ (Joint DMV and GAMM Annual Meeting)

Coupling the finite and boundary element methods with FEniCS and BEM++ (BAMC 2016)

FEM-BEM coupling, Maxwell's equations, and BEM++ (FEniCS'16)

Coupling the finite and boundary element methods with FEniCS and BEM++ (PDESoft 2016)

#### Teaching

In 2015-16 and 2016-17, I taught MATH6103: Differential and Integral Calculus at UCL. You can find my notes for this course at mscroggs.co.uk/6103.

**2015**

#### Conference talks

Solving FEM/BEM coupled problems with FEniCS and BEM++ (Strathclyde 26th Biennial Numerical Analysis Conference)