3,697 research outputs found
Satisfiability Modulo Theory based Methodology for Floorplanning in VLSI Circuits
This paper proposes a Satisfiability Modulo Theory based formulation for
floorplanning in VLSI circuits. The proposed approach allows a number of fixed
blocks to be placed within a layout region without overlapping and at the same
time minimizing the area of the layout region. The proposed approach is
extended to allow a number of fixed blocks with ability to rotate and flexible
blocks (with variable width and height) to be placed within a layout without
overlap. Our target in all cases is reduction in area occupied on a chip which
is of vital importance in obtaining a good circuit design. Satisfiability
Modulo Theory combines the problem of Boolean satisfiability with domains such
as convex optimization. Satisfiability Modulo Theory provides a richer modeling
language than is possible with pure Boolean SAT formulas. We have conducted our
experiments on MCNC and GSRC benchmark circuits to calculate the total area
occupied, amount of deadspace and the total CPU time consumed while placing the
blocks without overlapping. The results obtained shows clearly that the amount
of dead space or wasted space is reduced if rotation is applied to the blocks.Comment: 8 pages,5 figure
A Regularized Graph Layout Framework for Dynamic Network Visualization
Many real-world networks, including social and information networks, are
dynamic structures that evolve over time. Such dynamic networks are typically
visualized using a sequence of static graph layouts. In addition to providing a
visual representation of the network structure at each time step, the sequence
should preserve the mental map between layouts of consecutive time steps to
allow a human to interpret the temporal evolution of the network. In this
paper, we propose a framework for dynamic network visualization in the on-line
setting where only present and past graph snapshots are available to create the
present layout. The proposed framework creates regularized graph layouts by
augmenting the cost function of a static graph layout algorithm with a grouping
penalty, which discourages nodes from deviating too far from other nodes
belonging to the same group, and a temporal penalty, which discourages large
node movements between consecutive time steps. The penalties increase the
stability of the layout sequence, thus preserving the mental map. We introduce
two dynamic layout algorithms within the proposed framework, namely dynamic
multidimensional scaling (DMDS) and dynamic graph Laplacian layout (DGLL). We
apply these algorithms on several data sets to illustrate the importance of
both grouping and temporal regularization for producing interpretable
visualizations of dynamic networks.Comment: To appear in Data Mining and Knowledge Discovery, supporting material
(animations and MATLAB toolbox) available at
http://tbayes.eecs.umich.edu/xukevin/visualization_dmkd_201
Rapid mapping of digital integrated circuit logic gates via multi-spectral backside imaging
Modern semiconductor integrated circuits are increasingly fabricated at
untrusted third party foundries. There now exist myriad security threats of
malicious tampering at the hardware level and hence a clear and pressing need
for new tools that enable rapid, robust and low-cost validation of circuit
layouts. Optical backside imaging offers an attractive platform, but its
limited resolution and throughput cannot cope with the nanoscale sizes of
modern circuitry and the need to image over a large area. We propose and
demonstrate a multi-spectral imaging approach to overcome these obstacles by
identifying key circuit elements on the basis of their spectral response. This
obviates the need to directly image the nanoscale components that define them,
thereby relaxing resolution and spatial sampling requirements by 1 and 2 - 4
orders of magnitude respectively. Our results directly address critical
security needs in the integrated circuit supply chain and highlight the
potential of spectroscopic techniques to address fundamental resolution
obstacles caused by the need to image ever shrinking feature sizes in
semiconductor integrated circuits
- …