Phd Dissertation

Graph Neural Network for Integrated Circuits and Cyber-Physical Systems Security

Publication Date

January 1, 2023

Author(s)

Abstract

This Ph.D. dissertation presents a comprehensive investigation into addressing security and reliability challenges in embedded and Cyber-Physical Systems (CPS). Our research leverages advanced machine learning techniques such as Graph Neural Networks (GNN) to develop novel methodologies for cross-layer security analysis.This dissertation addresses the growing risk posed by the globalization of the Integrated Circuit (IC) supply chain, whereby the majority of the design, fabrication, and testing processes have been outsourced to untrusted third-party entities across the globe. This development has significantly increased the threat of malicious modifications, known as Hardware Trojans (HTs), being inserted into Third-Party Intellectual Property (3PIP). HTs pose a substantial risk to IC integrity, functionality, and performance. Despite numerous HT detection methods proposed in existing literature, most limitations include reliance on a golden reference circuit, lack of generalizability, limited detection scope, low localization resolution, and manual feature extraction and property definition. Furthermore, the equally important task of HT localization has been neglected. This research proposes an innovative, golden reference-free method for HT detection and localization at the pre-silicon stage of IC development, employing models based on GNN. The circuit design is converted into a graph that is an intrinsic data structure for hardware design and captures the computational structure and data dependencies. We develop a graph classification model to distinguish between HT-free and circuits infected with known or even unknown HTs. To push the boundaries further, we extract node attributes from the HDL code and devise a Graph Convolutional Network (GCN) that facilitates automatic feature extraction, enabling the classification of nodes as either Trojan or benign. This methodology offers an automated approach to HT detection and localization, relieving designers of the need for time-consuming manual code review. The developed method achieves exceptional performance in detecting HT-infected circuits and locating the HT. The approach outlined in this dissertation sets a new benchmark for HT detection and localization, offering a scalable, efficient, and highly accurate tool for securing the pre-silicon IC supply chain.This dissertation expands to encompass the challenges facing IP piracy. The productivity gap, coupled with time-to-market pressure, has led to increased interest in hardware Intellectual Property (IP) core design within the semiconductor industry, dramatically reducing design and verification costs. Recognizing these challenges, this dissertation proposes a novel IP piracy detection methodology, modeling circuits and assessing similarity between IP designs. Contrary to traditional methods that embed a signature within the circuit design, our method does not introduce additional hardware overhead, nor is it vulnerable to removal, masking, or forging attacks. This approach effectively exposes IP infringements, even when the original IP is complicated by the adversary to deceive the IP owner. To represent the circuit accurately for modeling, we translate the hardware design into a data-flow graph due to similar data types and properties and subsequently model it using state-of-the-art graph learning methods. This approach effectively complements the GNN-based techniques proposed earlier in this dissertation, presenting a robust and comprehensive suite of solutions for security and reliability challenges in the semiconductor industry. Moving to the CPS domain, the dissertation addresses security challenges in IoT systems through the development of adaptive anomaly detection methods. The first proposed approach utilizes IoT sensor data and fog computing to ensure data integrity and detect anomalous incidents. The proposed methodology incorporates our sensor association algorithm, LSTM neural networks, and Gaussian estimation for real-time anomaly detection. The dissertation further extends the research to multi-modal data fusion, where the integration of sensor and communication data using GNN enables improved anomaly detection, source identification, and recovery in IoT systems.Overall, this dissertation showcases the application of advanced techniques such as GNN and machine learning in enhancing security and reliability in hardware design and IoT systems. The proposed methodologies for anomaly detection, hardware Trojan detection, IP piracy detection, and cross-layer security analysis contribute to advancing the state-of-the-art in ensuring the integrity and security of critical systems in the digital era.

Suggested Citation
Rosin Yasaei (2023) Graph Neural Network for Integrated Circuits and Cyber-Physical Systems Security. PhD Dissertation. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/u4evf/cdi_proquest_journals_2854332836.

published journal article

Free transit for students to regain ridership: Users and boarding characteristics of LA Metro's GoPass program

Journal of Transport Geography

Publication Date

December 1, 2025

Abstract

The Los Angeles County Metropolitan Transportation Authority (LA Metro) started in October 2021 the largest free transit pass program in the U.S. to date. Known as GoPass, it serves students from kindergarten to community colleges in Los Angeles County, the most populated county in the U.S. Although many free transit pass programs have been created, few have been analyzed from the point of view of transit agencies (i.e., for the characteristics of their users and their impact on ridership). To address this gap, we first examine GoPass’ contribution to LA Metro’s bus boardings, before comparing selected characteristics of the students enrolled in GoPass in 2023 with census data. We find some opportunities for additional growth, including for female students. To understand GoPass usage, we estimated a generalized spatial regression model that explains annual GoPass boardings aggregated by census tract (detailed usage data are unavailable to protect the students’ privacy) using a broad range of socioeconomic and built environment variables. Our results confirm the presence of strong spatial effects. We find that census tracts with more young males, more transit stops, mixed land use, and more participating schools accessible within 30 min by transit have more GoPass boardings. Conversely, the number of GoPass boardings decreases with more access to private vehicles, property crimes, multifamily units, and a higher population density. A better understanding of the characteristics of GoPass users and GoPass usage is useful to improve GoPass and to inform transit agencies interested in creating similar programs.

Suggested Citation
Farzana Khatun and Jean-Daniel Saphores (2025) “Free transit for students to regain ridership: Users and boarding characteristics of LA Metro's GoPass program”, Journal of Transport Geography, 129, p. 104442. Available at: 10.1016/j.jtrangeo.2025.104442.

published journal article

The political economy of urban transport-system choice

Journal of Public Economics

Publication Date

August 1, 2006

Author(s)

Jan Brueckner, Harris Selod
Suggested Citation
Jan K. Brueckner and Harris Selod (2006) “The political economy of urban transport-system choice”, Journal of Public Economics, 90(6-7), pp. 983–1005. Available at: 10.1016/j.jpubeco.2005.06.004.

research report

A Statewide Optimal Resource Allocation Tool Using Geographic Information Systems, Spatial Analysis, and Regression Methods

Publication Date

November 1, 2008

Author(s)

Konstadinos Goulias, Thomas Golob, Sungsu (Stephen) Yoon

Final Report

UCB-ITS-PRR-2008-27

Abstract

The overall objective of this project is to develop an optimal resource allocation tool for the entire state of California using Geographic Information Systems and widely available data sources. As this tool evolves it will be used to make investment decisions in transportation infrastructure while accounting for their spatial and social distribution of impacts. Tools of this type do not exist due to lack of suitable planning support tools, lack of efforts in assembling data and information from a variety of sources, and lack of coordination in assembling the data. Suitable planning support tools can be created with analytical experimentation to identify the best methods and the first steps are taken in this project. Assembly of widely available data is also demonstrated in this project. Coordination of fragmented jurisdictions remains an elusive task that is left outside the project. When this project begun we confronted some of these issues and embarked in a path of feasibility demonstration in the form of a pilot project that gave us very encouraging results. In spite of this pilot nature aiming at demonstration of technical feasibility, substantive conclusions and findings are also extracted from each analytical step.In this project we have two parallel analytical tracks that are a statewide macroanalysis (called the zonal based approach herein) and an individual and household based microanalysis (called the person based approach herein). In the statewide macroanalysis we study efficiency and equity in resource allocation. Resources are intended as infrastructure availability and access to activity participation offered by the combined effect of transportation infrastructure and land use measured by indicators of accessibility. Stochastic frontiers are used to study efficiency and a particular type of inequality measurement called the Theil fractal inequality index is used to study equity in the macroanalysis. The outcome of this analysis are maps identifying places in California that enjoy higher levels of service when compared to the entire state and places which succeeded in allocating resources in a relatively better way than others. In the individual microanalysis we use the accessibility indicators from the macronalysis and expand them by defining a new set of indicators at a second level of spatial (dis)aggregation. Then we use them as explanatory factors of travel behavior with focus on the use of different travel models (e.g., driving alone, use of public transportation and so forth). As expected infrastructure availability and accessibility to activity opportunities has a significant and substantive effect on the use of different modes. Many resource allocation decisions, then, will impact behavior, which in turn influences the optimality and equity conditions. This implies that decisions about where and when to allocate resources in public and private transportation needs to account for changes in behavior in a dynamic fashion, using scenarios of accessibility provision and assessing their impact by studying activity and travel behavior changes.

Suggested Citation
Konstadinos G. Goulias, Thomas F. Golob and Seo Youn Yoon (2008) A Statewide Optimal Resource Allocation Tool Using Geographic Information Systems, Spatial Analysis, and Regression Methods. Final Report UCB-ITS-PRR-2008-27. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/2gt23996.

published journal article

Traffic equilibrium problem with route-specific costs: formulation and algorithms

Transportation Research Part B: Methodological

Publication Date

August 1, 2000

Author(s)

Hong Lo, Anthony Chen

Abstract

Using a new gap function recently proposed by Facchinei and Soares [Facchinei, F., Soares, J., 1995. Testing a new class of algorithms for nonlinear complementarity problems. In: Giannessi, F., Maugeri, A. (Eds.), Variational Inequalities and Network Equilibrium Problems. Plenum Press, New York], we convert the nonlinear complementarity problem (NCP) formulation for the traffic equilibrium problem to an equivalent unconstrained optimization. This equivalent formulation uses both route flows and the minimum origin–destination travel costs as the decision variables. Two unique features of this formulation are that: (i) it can model the traffic assignment problem with a general route cost structure; (ii) it is smooth, unconstrained, and that every stationary point of the minimization corresponds to a global minimum. These properties permit a number of efficient algorithms for its solution. Two solution approaches are developed to solve the proposed formulation. Numerical results using a route-specific cost structure are provided and compared with the classic traffic equilibrium problem, which assumes an additive route cost function.

Suggested Citation
Hong K. Lo and Anthony Chen (2000) “Traffic equilibrium problem with route-specific costs: formulation and algorithms”, Transportation Research Part B: Methodological, 34(6), pp. 493–513. Available at: 10.1016/S0191-2615(99)00035-1.

presentation

Analyzing the Impact of Land Use and Sociodemographics on Microtransit

Publication Date

October 10, 2025

Author(s)

Suggested Citation
Tim Wang (2025) “Analyzing the Impact of Land Use and Sociodemographics on Microtransit”. 2025 ITS-Irvine Emerging Scholars Transportation Research Showcase I, ITS-Irvine, 10 October. Available at: https://youtu.be/tizg3bjVN50?t=3412.

published journal article

How do information ambiguity and timing of contextual information affect managers' goal congruence in making investment decisions in good times vs. Bad times?

Journal of Risk and Uncertainty

Publication Date

September 1, 2005

Author(s)

Joanna L.Y. Ho, Robin Keller, Pamela Keltyka
Suggested Citation
Joanna L.Y. Ho, L. Robin Keller and Pamela Keltyka (2005) “How do information ambiguity and timing of contextual information affect managers' goal congruence in making investment decisions in good times vs. Bad times?”, Journal of Risk and Uncertainty, 31(2), pp. 163–186. Available at: 10.1007/s11166-005-3553-8.

conference paper

Extracting traffic patterns from loop detector data using multiple change point detection

Proceedings of the 93rd annual meeting of the transportation research board

Publication Date

January 1, 2014

Abstract

In this paper, we first introduce the Pruned Exact Linear Time (PELT)â??a segmentation approach for detecting multiple changepointsâ??to automatically identify the onset of congested periods of freeway operation using original, disaggregated, 30-second loop detector occupancy data. The purpose of the algorithm is to detect and map phase transitions in the occupancy data, keeping the general features of the traffic pattern while substantially reducing time in computation, retrieving, and presenting data with computation complexity that is only O(n). By using PELT, the start and end of the congestion period is identified automatically. The algorithm is tested on data from over 1000 mainline detectors in Orange County, California, USA both for a single day and for a month. The compression ratio of occupancy data is about 38.5, allowing an opportunity to analyze and monitor traffic in a more efficient way. This research provides an approach to quantify and display both the beginning of the congestion as well as total congestion duration on temporal-spatial maps that could lead to an inexpensive means to improve the quality of ramp metering settings and real time traffic monitoring.

Suggested Citation
Ming-Hsun Yang, Thuy T.B. Luong and Will Recker (2014) “Extracting traffic patterns from loop detector data using multiple change point detection”, in Proceedings of the 93rd annual meeting of the transportation research board, p. 14p.

conference paper

Dual-horizon forecasts and repositioning strategies for operating shared autonomous mobility fleets

Proceedings of the 99th annual meeting of the transportation research board

Publication Date

January 1, 2020

Author(s)

Florian Dandl, Michael Hyland, Klaus Bogenberger, Hani Mahmassani
Suggested Citation
Florian Dandl, Michael Hyland, Klaus Bogenberger and Hani Mahmassani (2020) “Dual-horizon forecasts and repositioning strategies for operating shared autonomous mobility fleets”, in Proceedings of the 99th annual meeting of the transportation research board.

published journal article

Well-being and safety among inpatient psychiatric staff: The impact of conflict, assault, and stress reactivity

Administration and policy in mental health

Publication Date

September 1, 2015

Author(s)

Erin L. Kelly, Karissa Fenwick, John S. Brekke, Raymond Novaco
Suggested Citation
Erin L. Kelly, Karissa Fenwick, John S. Brekke and Raymond W. Novaco (2015) “Well-being and safety among inpatient psychiatric staff: The impact of conflict, assault, and stress reactivity”, Administration and policy in mental health, 43(5), pp. 703–716. Available at: 10.1007/s10488-015-0683-4.