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Topology Sensistivity Miloslav Capek Department of Electromagnetic Field Czech Technical University in Prague, Czech Republic miloslav.capek@fel.cvut.cz Seminar Lund, Sweden October 24, 2018 Miloslav Capek Topology Sensistivity 1 /


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SLIDE 1

Topology Sensistivity

Miloslav ˇ Capek

Department of Electromagnetic Field Czech Technical University in Prague, Czech Republic miloslav.capek@fel.cvut.cz

Seminar Lund, Sweden October 24, 2018

Miloslav ˇ Capek Topology Sensistivity 1 / 31

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SLIDE 2

Outline

1

Shape Synthesis

2

Discretization of a Model

3

Shape Synthesis Techniques

4

Topology Sensitivity: Motivation

5

Topology Sensitivity: Derivation

6

Topology Sensitivity: Examples

7

Conversion to a Graph: Greedy Algorithm

8

Concluding Remarks and Future Work

This talk concerns: ◮ electric currents in vacuum, ◮ time-harmonic quantities, i.e., A (r, t) = Re {A (r) exp (jωt)}.

Miloslav ˇ Capek Topology Sensistivity 2 / 31

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SLIDE 3

Shape Synthesis

Analysis × Synthesis

Miloslav ˇ Capek Topology Sensistivity 3 / 31

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SLIDE 4

Shape Synthesis

Analysis × Synthesis

Analysis (A) ◮ Shape Ω is given, BCs are known, determine EM quantities. g = L {J (r)} = Af f ≡

  • Ω, Ei

, g ≡ {pi}

Miloslav ˇ Capek Topology Sensistivity 3 / 31

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SLIDE 5

Shape Synthesis

Analysis × Synthesis

Analysis (A) ◮ Shape Ω is given, BCs are known, determine EM quantities. g = L {J (r)} = Af ? Synthesis (S ≡ A−1) ◮ EM behavior is specified, neither Ω nor BCs are known. f = Sg = A−1g f ≡

  • Ω, Ei

, g ≡ {pi}

Miloslav ˇ Capek Topology Sensistivity 3 / 31

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SLIDE 6

Shape Synthesis

Synthesis

How to get f = A−1g? Questions inherently related to synthesis are1 (f ≡

  • Ω, Ei

, g ≡ {pi})

  • 1. Can g be chosen arbitrary?
  • 2. If g is such that there exists a solution f, is that solution unique?
  • 3. If g is known only approximately, which is always the case, is the corresponding

solution for f close to the exact one?

  • 4. If f is not exactly realized what effect will this have on Af?
  • 1G. Deschamps and H. Cabayan, “Antenna synthesis and solution of inverse problems by regularization methods”,

IEEE Transactions on Antennas and Propagation, vol. 20, no. 3, pp. 268–274, 1972. doi: 10.1109/tap.1972.1140197. [Online]. Available: https://doi.org/10.1109/tap.1972.1140197

Miloslav ˇ Capek Topology Sensistivity 4 / 31

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SLIDE 7

Shape Synthesis

Synthesis

How to get f = A−1g? Questions inherently related to synthesis are1 (f ≡

  • Ω, Ei

, g ≡ {pi})

  • 1. Can g be chosen arbitrary? No.
  • 2. If g is such that there exists a solution f, is that solution unique? No.
  • 3. If g is known only approximately, which is always the case, is the corresponding

solution for f close to the exact one? No.

  • 4. If f is not exactly realized what effect will this have on Af? Potentially huge.

Generally, infinitely many possibilities and local minima → need for shape discretization.

  • 1G. Deschamps and H. Cabayan, “Antenna synthesis and solution of inverse problems by regularization methods”,

IEEE Transactions on Antennas and Propagation, vol. 20, no. 3, pp. 268–274, 1972. doi: 10.1109/tap.1972.1140197. [Online]. Available: https://doi.org/10.1109/tap.1972.1140197

Miloslav ˇ Capek Topology Sensistivity 4 / 31

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SLIDE 8

Discretization of a Model

Discretization

Ω σ → ∞

(PEC)

Original problem.

Miloslav ˇ Capek Topology Sensistivity 5 / 31

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SLIDE 9

Discretization of a Model

Discretization

Ω σ → ∞

(PEC)

Original problem.

Ω ǫ0, µ0

Equivalent problem.

Miloslav ˇ Capek Topology Sensistivity 5 / 31

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SLIDE 10

Discretization of a Model

Discretization

Ω σ → ∞

(PEC)

Original problem.

Ω ǫ0, µ0

Equivalent problem.

ΩT

Triangularized domain ΩT .

Structure Ω → ΩT , current density in vacuum J (r), r ∈ ΩT .

Miloslav ˇ Capek Topology Sensistivity 5 / 31

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SLIDE 11

Discretization of a Model

Operators Represented In RWG Basis Functions

Starting point in this work is a given discretization into T triangles ti, ΩT =

T

  • i=1

ti.

Miloslav ˇ Capek Topology Sensistivity 6 / 31

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SLIDE 12

Discretization of a Model

Operators Represented In RWG Basis Functions

Starting point in this work is a given discretization into T triangles ti, ΩT =

T

  • i=1

ti. RWG basis functions {ψn (r)} are applied as J (r) ≈

N

  • n=1

Inψn (r) , where N is the number of all inner edges.

P +

n

P −

n

ρ+

n

ρ−

n

A+

n

A−

n

ln T +

n

T −

n

O r y z x ψn (r) = ln 2A±

n

ρ±

n RWG basis function ψn (r).

Miloslav ˇ Capek Topology Sensistivity 6 / 31

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SLIDE 13

Discretization of a Model

Operators Represented In RWG Basis Functions

Starting point in this work is a given discretization into T triangles ti, ΩT =

T

  • i=1

ti. RWG basis functions {ψn (r)} are applied as J (r) ≈

N

  • n=1

Inψn (r) , where N is the number of all inner edges. Matrix representation of the operators used J, AJ = [I∗

mψm, AψnIn] = IHAI.

P +

n

P −

n

ρ+

n

ρ−

n

A+

n

A−

n

ln T +

n

T −

n

O r y z x ψn (r) = ln 2A±

n

ρ±

n RWG basis function ψn (r).

Miloslav ˇ Capek Topology Sensistivity 6 / 31

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SLIDE 14

Shape Synthesis Techniques

Shape Synthesis: Properties and Approaches

  • 1. Designers’ skill and knowledge.
  • 2. Parametric sweeps.
  • 3. Heuristic algorithms (global optimization).
  • 4. Topology optimization (local optimization).

Miloslav ˇ Capek Topology Sensistivity 7 / 31

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SLIDE 15

Shape Synthesis Techniques

Shape Synthesis: Properties and Approaches

  • 1. Designers’ skill and knowledge.
  • Nonintuitive/complex design?
  • 2. Parametric sweeps.
  • What parameters? How many?
  • 3. Heuristic algorithms (global optimization).
  • Convergence. No-free-lunch. “Solution.”
  • 4. Topology optimization (local optimization).
  • This talk. . . partly.

Optimal solution: ◮ Combination of all approaches.

Miloslav ˇ Capek Topology Sensistivity 7 / 31

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SLIDE 16

Shape Synthesis Techniques

Topology Optimization

minimize f =

F (ρ (r)) dV subject to

ρ dV − V0 ≤ 0 ◮ min. compliance → max. stiffness ◮ solved within FEM ◮ mesh dependence ◮ instability (chess board)

Miloslav ˇ Capek Topology Sensistivity 8 / 31

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SLIDE 17

Shape Synthesis Techniques

Topology Optimization

minimize f =

F (ρ (r)) dV subject to

ρ dV − V0 ≤ 0 ◮ min. compliance → max. stiffness ◮ solved within FEM ◮ mesh dependence ◮ instability (chess board)

1216 × 3456 × 256 ≈ 1.1 · 109 unknowns, FEM2.

  • 2N. Aage, E. Andreassen, B. S. Lazarov, et al., “Giga-voxel computational morphogenesis for structural design”,

Nature, vol. 550, pp. 84–86, 2017. doi: 10.1038/nature23911

Miloslav ˇ Capek Topology Sensistivity 8 / 31

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SLIDE 18

Shape Synthesis Techniques

Topology Optimization in EM

State-of-the-art in mechanics, serious problems in EM3 ◮ “gray” elements, rounding yields different results, ◮ numerical oscillation (chessboard), ◮ more sensitive to local minima (current paths?), ◮ threshold function for MoM. Fundamental difference between EM vector field and stiffness in mechanics?

Histogram of the best candidates found for minI Q, NSGA-II.

  • 3S. Liu, Q. Wang, and R. Gao, “A topology optimization method for design of small GPR antennas”,
  • Struct. Multidisc. Optim.,
  • vol. 50, pp. 1165–1174, 2014. doi: 10.1007/s00158-014-1106-y

Miloslav ˇ Capek Topology Sensistivity 9 / 31

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SLIDE 19

Topology Sensitivity: Motivation

Topology Sensitivity

Idea behind this work Let us accept NP-hardness of the problem, do brute force, but do it cleverly. . .

Miloslav ˇ Capek Topology Sensistivity 10 / 31

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SLIDE 20

Topology Sensitivity: Motivation

Topology Sensitivity

Idea behind this work Let us accept NP-hardness of the problem, do brute force, but do it cleverly. . . ◮ Inspired by pixeling4, but RWG functions are the unknowns (T vs. N unknowns). ◮ Fixed mesh grid ΩT : operators calculated once, results comparable with the bounds. ◮ Woodbury identity employed: get rid of repetitive matrix inversion! ◮ Feeding is specified at the beginning.

  • 4Y. Rahmat-Samii, J. M. Kovitz, and H. Rajagopalan, “Nature-inspired optimization techniques in communication antenna

design”,

  • Proc. IEEE, vol. 100, no. 7, pp. 2132–2144, 2012. doi: 10.1109/JPROC.2012.2188489

Miloslav ˇ Capek Topology Sensistivity 10 / 31

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SLIDE 21

Topology Sensitivity: Motivation

Comparison of Pixeling Techniques

Pixel removal

T1 T2 T3 T4 T5 T6 T7 T8

Z11 Z12 Z13 · · · Z1N Z21 Z22 Z23 · · · Z2N Z31 Z32 Z33 · · · Z3N . . . . . . . . . ... . . . ZN1 ZN2 ZN3 · · · ZNN                      

Classical pixeling removes metallic patches5.

(ZG + ZL) I = ZI = V

  • 5Y. Rahmat-Samii, J. M. Kovitz, and H. Rajagopalan, “Nature-inspired optimization techniques in communication antenna

design”,

  • Proc. IEEE, vol. 100, no. 7, pp. 2132–2144, 2012. doi: 10.1109/JPROC.2012.2188489

Miloslav ˇ Capek Topology Sensistivity 11 / 31

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SLIDE 22

Topology Sensitivity: Motivation

Comparison of Pixeling Techniques

Pixel removal

T1 T2 T3 T4 T5 T6 T7 T8

Z11 Z12 Z13 · · · Z1N Z21 Z22 Z23 · · · Z2N Z31 Z32 Z33 · · · Z3N . . . . . . . . . ... . . . ZN1 ZN2 ZN3 · · · ZNN                      

Classical pixeling removes metallic patches5.

(ZG + ZL) I = ZI = V

Edge removal

ψ1 ψ2 ψ3 ψ4 ψ5 ψ6 ψ7 ψ8 ψ9

· · · Y22 Y23 · · · Y2N Y32 Y33 · · · Y2N . . . . . . . . . ... . . . YN2 YN3 · · · YNN                      

Proposed pixeling removes true degrees of freedom of MoM formulation.

I = Z−1V = YV

  • 5Y. Rahmat-Samii, J. M. Kovitz, and H. Rajagopalan, “Nature-inspired optimization techniques in communication antenna

design”,

  • Proc. IEEE, vol. 100, no. 7, pp. 2132–2144, 2012. doi: 10.1109/JPROC.2012.2188489

Miloslav ˇ Capek Topology Sensistivity 11 / 31

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SLIDE 23

Topology Sensitivity: Motivation

Pixeling and Edge Removal

Comparison of the longest meander possible for classical pixeling and edge removal.

◮ “Infinitesimally” small perturbation of a structure ΩT is a removal of RWG edge.

Miloslav ˇ Capek Topology Sensistivity 12 / 31

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SLIDE 24

Topology Sensitivity: Derivation

Incorporation of Lumped Element R∞

(ZG + ZL) I = ZI = V

Miloslav ˇ Capek Topology Sensistivity 13 / 31

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SLIDE 25

Topology Sensitivity: Derivation

Incorporation of Lumped Element R∞

(ZG + ZL) I = ZI = V Lumped element with resistivity R∞ ZL,nn = R∞ ⇔ n ∈ B Example: B = {1, 3}

Miloslav ˇ Capek Topology Sensistivity 13 / 31

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SLIDE 26

Topology Sensitivity: Derivation

Incorporation of Lumped Element R∞

(ZG + ZL) I = ZI = V Lumped element with resistivity R∞ ZL,nn = R∞ ⇔ n ∈ B CB,nn = ⇔ n ∈ B 1 ⇔

  • therwise

(All columns containing only zeros are removed.) Example: B = {1, 3} CB = 1 · · · 1 · · · T

Miloslav ˇ Capek Topology Sensistivity 13 / 31

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SLIDE 27

Topology Sensitivity: Derivation

Incorporation of Lumped Element R∞

(ZG + ZL) I = ZI = V Lumped element with resistivity R∞ ZL,nn = R∞ ⇔ n ∈ B CB,nn = ⇔ n ∈ B 1 ⇔

  • therwise

(All columns containing only zeros are removed.) ZL = CBR∞CT

B,

Example: B = {1, 3} CB = 1 · · · 1 · · · T CBR∞CT

B =

       R∞ · · · · · · R∞ · · · . . . . . . . . . ... . . . · · ·       

Miloslav ˇ Capek Topology Sensistivity 13 / 31

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SLIDE 28

Topology Sensitivity: Derivation

Utilization of Woodbury Formula

Definitions Z = ZG + ZL = ZG + CBR∞CT

B,

I = Z−1V = YV.

Miloslav ˇ Capek Topology Sensistivity 14 / 31

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SLIDE 29

Topology Sensitivity: Derivation

Utilization of Woodbury Formula

Definitions Z = ZG + ZL = ZG + CBR∞CT

B,

I = Z−1V = YV. Sherman-Morrison-Woodbury formula (A + EBF)−1 = A−1 − A−1E

  • B−1 + FA−1E

−1 FA−1

Miloslav ˇ Capek Topology Sensistivity 14 / 31

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SLIDE 30

Topology Sensitivity: Derivation

Utilization of Woodbury Formula

Definitions Z = ZG + ZL = ZG + CBR∞CT

B,

I = Z−1V = YV. Sherman-Morrison-Woodbury formula (A + EBF)−1 = A−1 − A−1E

  • B−1 + FA−1E

−1 FA−1 Y = Z−1 = Z−1

G − Z−1 G CB

1 R∞ 1D + CT

BZ−1 G CB

−1 CT

BZ−1 G

Miloslav ˇ Capek Topology Sensistivity 14 / 31

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SLIDE 31

Topology Sensitivity: Derivation

Utilization of Woodbury Formula

Definitions Z = ZG + ZL = ZG + CBR∞CT

B,

I = Z−1V = YV. Sherman-Morrison-Woodbury formula (A + EBF)−1 = A−1 − A−1E

  • B−1 + FA−1E

−1 FA−1 Y = Z−1 = Z−1

G − Z−1 G CB

1 R∞ 1D + CT

BZ−1 G CB

−1 CT

BZ−1 G

For Z−1

G = YG and R∞ → ∞

Y = YG − YGCB

  • CT

BYGCB

−1 CT

BYG.

Miloslav ˇ Capek Topology Sensistivity 14 / 31

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SLIDE 32

Topology Sensitivity: Derivation

Simplification With Indexing Property of Matrix CB

Y = YG − YGCB

  • CT

BYGCB

−1CT

BYG.

Miloslav ˇ Capek Topology Sensistivity 15 / 31

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SLIDE 33

Topology Sensitivity: Derivation

Simplification With Indexing Property of Matrix CB

Y = YG − YGCB

  • CT

BYGCB

−1CT

BYG.

For one (n-th) edge removed, |B| = 1: YGCB = yG,n,

  • CT

BYGCB

−1 = 1 Ynn , CT

BYG = yT G,n.

Miloslav ˇ Capek Topology Sensistivity 15 / 31

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SLIDE 34

Topology Sensitivity: Derivation

Simplification With Indexing Property of Matrix CB

Y = YG − YGCB

  • CT

BYGCB

−1CT

BYG.

For one (n-th) edge removed, |B| = 1: YGCB = yG,n,

  • CT

BYGCB

−1 = 1 Ynn , CT

BYG = yT G,n.

Notice CB is indexing matrix (MATLAB) only. . . Y = YG − yG,nyT

G,n

Ynn .

Miloslav ˇ Capek Topology Sensistivity 15 / 31

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SLIDE 35

Topology Sensitivity: Derivation

Incorporation of Fixed and Localized Feeding

Imagine further, that only one (f-th) edge is fed Vf = V0

  • · · ·

lf · · · T .

Miloslav ˇ Capek Topology Sensistivity 16 / 31

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SLIDE 36

Topology Sensitivity: Derivation

Incorporation of Fixed and Localized Feeding

Imagine further, that only one (f-th) edge is fed Vf = V0

  • · · ·

lf · · · T . Ifn =

  • YG −

yG,nyT

G,n

Ynn

  • Vf = · · · = If −

lfln l2

n

Yfn Ynn

  • V0lnyG,n = If + ζfnIn,

with If = YGVf and ζij = −lilj l2

j

Yij Yjj = −Zin,jj Zin,ij .

Miloslav ˇ Capek Topology Sensistivity 16 / 31

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SLIDE 37

Topology Sensitivity: Derivation

Incorporation of Fixed and Localized Feeding

Imagine further, that only one (f-th) edge is fed Vf = V0

  • · · ·

lf · · · T . Ifn =

  • YG −

yG,nyT

G,n

Ynn

  • Vf = · · · = If −

lfln l2

n

Yfn Ynn

  • V0lnyG,n = If + ζfnIn,

with If = YGVf and ζij = −lilj l2

j

Yij Yjj = −Zin,jj Zin,ij . This is equivalent to a specific two-port feeding V = V0

  • . . .

lf . . . ζfnln . . . T .

Miloslav ˇ Capek Topology Sensistivity 16 / 31

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SLIDE 38

Topology Sensitivity: Derivation

Topology Sensitivity

All potential removals at once: IfB =

  • If + ζf1I1

· · · If + ζfNIN

  • .

Miloslav ˇ Capek Topology Sensistivity 17 / 31

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SLIDE 39

Topology Sensitivity: Derivation

Topology Sensitivity

All potential removals at once: IfB =

  • If + ζf1I1

· · · If + ζfNIN

  • .

An antenna observable defined as quadratic form x (I) = IHAI IHBI. is calculated with a Hadamard product (vectorization) x (IfB) = diag

  • IH

fBAIfB

  • ⊘ diag
  • IH

fBBIfB

  • .

Miloslav ˇ Capek Topology Sensistivity 17 / 31

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SLIDE 40

Topology Sensitivity: Derivation

Topology Sensitivity

All potential removals at once: IfB =

  • If + ζf1I1

· · · If + ζfNIN

  • .

An antenna observable defined as quadratic form x (I) = IHAI IHBI. is calculated with a Hadamard product (vectorization) x (IfB) = diag

  • IH

fBAIfB

  • ⊘ diag
  • IH

fBBIfB

  • .

Finally, topology sensitivity is defined here as τ fB (x, ΩT ) = x (IfB) − x (If) ≈ ∇x (If) .

Miloslav ˇ Capek Topology Sensistivity 17 / 31

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SLIDE 41

Topology Sensitivity: Examples

Example: Thin-strip Dipole – Input Reactance

−0.4 −0.2 0.2 0.4 500 1000 ξ/ℓ τfS (|Xin|, Ωdip)

kℓ = 3π/4 kℓ = π kℓ = 3π/2

Topology sensitivity τ fB (|Xin|) of a center-fed dipole Ωdip, discretized into N = 79 basis functions, of three different

Miloslav ˇ Capek Topology Sensistivity 18 / 31

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SLIDE 42

Topology Sensitivity: Examples

Example: Thin-strip Dipole – Q-factor

1 2 3 4 5 6 7 8 1 2 3 4 5 6 A B

A B

kℓ Q/Qlb

center-fed dipole

  • ptimized shape

Radiation Q-factor of center-fed dipole Ωdip, discretized into N = 79 basis functions.

Miloslav ˇ Capek Topology Sensistivity 19 / 31

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SLIDE 43

Conversion to a Graph: Greedy Algorithm

Greedy Step

A discretization establishes a graph. G (V, E) = G (P, E) → {Ti} → {ψn (r)}

Miloslav ˇ Capek Topology Sensistivity 20 / 31

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SLIDE 44

Conversion to a Graph: Greedy Algorithm

Graph Representation: Reduction to Tree

1111 1110 1101 1100 1011 1010 1001 1000 0111 0110 0101 0100 0011 0010 0001 0000

6 2

  • 6
  • 5

8

  • 9
  • 7

10 4

  • 1
  • 9

4

  • 9
  • 9
  • 8

6 6 4

  • 7

3 9 3 6

  • 1
  • 1

7

  • 8
  • 7

Synthesis problem for N = 4 as a directional binary tree.

Miloslav ˇ Capek Topology Sensistivity 21 / 31

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SLIDE 45

Conversion to a Graph: Greedy Algorithm

Graph Representation: Reduction to Tree

1111 1110 1101 1100 1011 1010 1001 1000 0111 0110 0101 0100 0011 0010 0001 0000

6 2

  • 6
  • 5

8

  • 9
  • 7

10 4

  • 1
  • 9

4

  • 9
  • 9
  • 8

6 6 4

  • 7

3 9 3 6

  • 1
  • 1

7

  • 8
  • 7

Synthesis problem for N = 4 as a directional binary tree. 28 25 29 24 28 18 28 28 24 22 28 29 23 20 24 28 Greedy algorithm as gradient search in directional graph.

Miloslav ˇ Capek Topology Sensistivity 21 / 31

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SLIDE 46

Conversion to a Graph: Greedy Algorithm

Greedy Algorithm

One gradient-based search through the entire tree (the most pessimistic run): ◮ max (N − 1) series ◮ N (N − 1) (N − 2) · · · = N! evaluations Shermann-Morrison-Woodbury: N − n speed-up at every tree level Note of solvability of the problem Problem is not convex → combination of global and local algorithms.

Miloslav ˇ Capek Topology Sensistivity 22 / 31

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SLIDE 47

Conversion to a Graph: Greedy Algorithm

Greedy Algorithm – Example: Rectangular Plate

Miloslav ˇ Capek Topology Sensistivity 23 / 31

4 4 14 1 19 5 8 9 26 1 1 13 14 37 1 1 17 18 43 1 18 17 37 1 14 13 26 1 1 9 8 14 1 1 4 4 5 19 1 9 1 30 10 −1 3 −10 −4 2 −1 −1 −5 −1 −1 −3 −1 −1 −10 −3 −1 −1 −1 2 −4 3 9 10 30 1 1 11 26 11 1 −1 −1 3 2 5 −4 9 −1 1 5 −13 −8 −1164 −854 −937 11 −8 −13 9 11 −937 −854 −4 5 −1 5 1 −1 1 2 3 −1 11 1 11 26 2 7 27 6 7 5 −1 85 22 23 5 −4 186 73 74 −478 −18 192 198 −18 −478 186 198 192 −4 5 85 74 73 −1 5 27 23 22 7 2 7 6

slide-48
SLIDE 48

Conversion to a Graph: Greedy Algorithm

Compression of the Problem

50 100 150 200 250 300 350 20 40 60 80

reduction per. t (1 : 380) p = ∞ 79.7 s p = 1 84.9 s p = 5 66.4 s p = 50 63.3 s

iteration i total comp. time, t(1 : i) [s]

Miloslav ˇ Capek Topology Sensistivity 24 / 31

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SLIDE 49

Conversion to a Graph: Greedy Algorithm

Number of Evaluated Antennas and Computational Time

plate (8 × 4) plate (14 × 7) sphere electrical size (ka) 0.5 0.5 0.5 basis functions (N) 180 567 900 number of iterations (I) 71 279 380 evaluated antennas 10332 119420 270129 realized Q/Qlb 1.57 1.45 1.51 edge removal (p = ∞) 0.30 s 23.5 s 79.7 s edge removal (p = 50) 0.28 s 19.4 63.6 s edge removal (p = 1) 0.43 s 23.3 s 84.9 s classical pixel removal 10 s 1437 s 10500 s

Miloslav ˇ Capek Topology Sensistivity 25 / 31

slide-50
SLIDE 50

Concluding Remarks and Future Work

Concluding Remarks6

◮ How to add any edge back?

  • Generalized Woodbury (slower than removal).

Ynew = Z zn zT

n

Znn −1

  • Matrix inverse pivots (big data, graph clustering).

◮ Add topology sensitivity into heuristic optimization as a local step. ◮ Utilization for “data mining”. ◮ Further study of graph representation and formal synthesis problem.

Ω Ω− Ω+

Adding and removing DOF.

  • 6M. Capek, L. Jelinek, and M. Gustafsson, “Shape synthesis based on topology sensitivity”, , 2018, submitted, arxiv:

1808.02479. [Online]. Available: https://arxiv.org/abs/1808.02479

Miloslav ˇ Capek Topology Sensistivity 26 / 31

slide-51
SLIDE 51

Concluding Remarks and Future Work

Computational Complexity

Characterization of the synthesis problem

Number of inner edges N Levels of the tree N + 1 Total number of solutions 2N Number of connections down N − n Number of connections up n Number of nodes at the n-th level N! n! (N − n)! = N n

  • Number of connections down from the n-th level

n N n

  • Miloslav ˇ

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SLIDE 52

Concluding Remarks and Future Work

All Approaches to Synthesis at Once

Do not find an approximative solution of the exact model but, instead, find an exact solution of the approximate model.

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SLIDE 53

Concluding Remarks and Future Work

Moving in the Solution Space

11 · · · 11 11 · · · 00 00 · · · 00 00 · · · 11

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SLIDE 54

Concluding Remarks and Future Work

Moving in the Solution Space

11 · · · 11 11 · · · 00 00 · · · 00 00 · · · 11

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SLIDE 55

Concluding Remarks and Future Work

Moving in the Solution Space

11 · · · 11 11 · · · 00 00 · · · 00 00 · · · 11

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SLIDE 56

Concluding Remarks and Future Work

Moving in the Solution Space

11 · · · 11 11 · · · 00 00 · · · 00 00 · · · 11

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SLIDE 57

Concluding Remarks and Future Work

Moving in the Solution Space

11 · · · 11 11 · · · 00 00 · · · 00 00 · · · 11

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SLIDE 58

Concluding Remarks and Future Work

Moving in the Solution Space

11 · · · 11 11 · · · 00 00 · · · 00 00 · · · 11

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SLIDE 59

Concluding Remarks and Future Work

Synthesis – Generalized Framework

Complete and general description of synthesis. Desired quantity: ˆ I (source current), given quantity: YΩ (source region). ˆ I =

  • 1 − YGCB
  • Z−1

L + CT BYGCB

−1 CT

B

  • YGCFvV0

ˆ I = (1 − P) YΩV YΩ initial system to be optimized V excitation (external/boundary condition) I solution to original (arbitrarily shaped) structure Ω P (any) modification of the initial (arbitrarily shaped) structure Ω

Miloslav ˇ Capek Topology Sensistivity 30 / 31

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SLIDE 60

Questions?

For a complete PDF presentation see

capek.elmag.org

Miloslav ˇ Capek miloslav.capek@fel.cvut.cz

  • 24. 10. 2018, v1.01

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