30 research outputs found
Quadratic backward propagation of variance for nonlinear statistical circuit modeling
Accurate statistical modeling and simulation are keys to ensure that integrated circuits (ICs) meet specifications over the stochastic variations inherent in IC manufacturing technologies. Backward propagation of variance (BPV) is a general technique for statistical modeling of semiconductor devices. However, the BPV approach assumes that statistical fluctuations are not large, so that variations in device electrical performances can be modeled as linear functions of process parameters. With technology scaling, device performance variability over manufacturing variations becomes nonlinear. In this paper we extend the BPV technique to take into account these nonlinearities. We present the theory behind the technique, and apply it to specific examples. We also investigate the effectiveness of several possible solution algorithms
Design, Analysis and Test of Logic Circuits under Uncertainty.
Integrated circuits are increasingly susceptible to uncertainty caused by soft
errors, inherently probabilistic devices, and manufacturing variability. As device technologies
scale, these effects become detrimental to circuit reliability. In order to address
this, we develop methods for analyzing, designing, and testing circuits subject to probabilistic
effects. Our main contributions are: 1) a fast, soft-error rate (SER) analyzer
that uses functional-simulation signatures to capture error effects, 2) novel design techniques
that improve reliability using little area and performance overhead, 3) a matrix-based
reliability-analysis framework that captures many types of probabilistic faults, and
4) test-generation/compaction methods aimed at probabilistic faults in logic circuits.
SER analysis must account for the main error-masking mechanisms in ICs: logic,
timing, and electrical masking. We relate logic masking to node testability of the circuit
and utilize functional-simulation signatures, i.e., partial truth tables, to efficiently compute
estability (signal probability and observability). To account for timing masking, we compute
error-latching windows (ELWs) from timing analysis information. Electrical masking
is incorporated into our estimates through derating factors for gate error probabilities. The
SER of a circuit is computed by combining the effects of all three masking mechanisms
within our SER analyzer called AnSER.
Using AnSER, we develop several low-overhead techniques that increase reliability,
including: 1) an SER-aware design method that uses redundancy already present within
the circuit, 2) a technique that resynthesizes small logic windows to improve area and
reliability, and 3) a post-placement gate-relocation technique that increases timing masking by decreasing ELWs.
We develop the probabilistic transfer matrix (PTM) modeling framework to analyze
effects beyond soft errors. PTMs are compressed into algebraic decision diagrams (ADDs)
to improve computational efficiency. Several ADD algorithms are developed to extract
reliability and error susceptibility information from PTMs representing circuits.
We propose new algorithms for circuit testing under probabilistic faults, which require
a reformulation of existing test techniques. For instance, a test vector may need to be
repeated many times to detect a fault. Also, different vectors detect the same fault with
different probabilities. We develop test generation methods that account for these differences, and integer linear programming (ILP) formulations to optimize test sets.Ph.D.Computer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/61584/1/smita_1.pd
Bioinformatics
This book is divided into different research areas relevant in Bioinformatics such as biological networks, next generation sequencing, high performance computing, molecular modeling, structural bioinformatics, molecular modeling and intelligent data analysis. Each book section introduces the basic concepts and then explains its application to problems of great relevance, so both novice and expert readers can benefit from the information and research works presented here
BNAIC 2008:Proceedings of BNAIC 2008, the twentieth Belgian-Dutch Artificial Intelligence Conference
National freight transport planning: towards a Strategic Planning Extranet Decision Support System (SPEDSS)
This thesis provides a `proof-of-concept' prototype and a design architecture for a
Object Oriented (00) database towards the development of a Decision Support
System (DSS) for the national freight transport planning problem. Both governments
and industry require a Strategic Planning Extranet Decision Support System
(SPEDSS) for their effective management of the national Freight Transport Networks
(FTN).
This thesis addresses the three key problems for the development of a SPEDSS to
facilitate national strategic freight planning: 1) scope and scale of data available and
required; 2) scope and scale of existing models; and 3) construction of the software.
The research approach taken embodies systems thinking and includes the use of:
Object Oriented Analysis and Design (OOA/D) for problem encapsulation and
database design; artificial neural network (and proposed rule extraction) for
knowledge acquisition of the United States FTN data set; and an iterative Object
Oriented (00) software design for the development of a `proof-of-concept'
prototype. The research findings demonstrate that an 00 approach along with the use
of 00 methodologies and technologies coupled with artificial neural networks
(ANNs) offers a robust and flexible methodology for the analysis of the FTN problem
domain and the design architecture of an Extranet based SPEDSS.
The objectives of this research were to: 1) identify and analyse current problems and
proposed solutions facing industry and governments in strategic transportation
planning; 2) determine the functional requirements of an FTN SPEDSS; 3) perform a
feasibility analysis for building a FTN SPEDSS `proof-of-concept' prototype and
(00) database design; 4) develop a methodology for a national `internet-enabled'
SPEDSS model and database; 5) construct a `proof-of-concept' prototype for a
SPEDSS encapsulating identified user requirements; 6) develop a methodology to
resolve the issue of the scale of data and data knowledge acquisition which would act
as the `intelligence' within a SPDSS; 7) implement the data methodology using
Artificial Neural Networks (ANNs) towards the validation of it; and 8) make recommendations for national freight transportation strategic planning and further
research required to fulfil the needs of governments and industry.
This thesis includes: an 00 database design for encapsulation of the FTN; an
`internet-enabled' Dynamic Modelling Methodology (DMM) for the virtual
modelling of the FTNs; a Unified Modelling Language (UML) `proof-of-concept'
prototype; and conclusions and recommendations for further collaborative research
are identified