VehicleSec '26 Call for Papers
Sponsored by USENIX, the Advanced Computing Systems Association.
The 4th USENIX Symposium on Vehicle Security and Privacy (VehicleSec
'26) will be held on August 10–11, 2026, in conjunction with the 35th
USENIX Security Symposium in Baltimore, MD, USA.
Important Dates
Paper submissions due: Tuesday, February 24, 2026, 23:59 AoE
(Anywhere on Earth) time
Notification of paper acceptance: Tuesday, April 7, 2026
Final papers due: Wednesday, June 10, 2026
Demo/Poster/Tutorial/Lightning Talk submissions due: Tuesday,
May 5, 2026 Tuesday, May 12, 2026
Notification of Demo/Poster/Tutorial/Lightning Talk acceptance:
Tuesday, May 26, 2026
Demo/Poster/Tutorial final abstracts due: Wednesday, June 3, 2026
Download Call for Papers PDF
Overview
A vehicle is a machine that transports people and/or goods in one or
more physical domains, such as on the ground (e.g., cars, bicycles,
motorcycles, trucks, buses, scooters, trains), in the air (e.g.,
drones, airplanes, helicopters), in the water (e.g., ships,
submarine), and in space (e.g., spacecraft). Due to their safety and
mission-critical nature, the security and privacy of vehicles can pose
direct threats to passengers, owners, operators, and the
infrastructure. Recent improvements in vehicle autonomy and
connectivity (e.g., autonomous driving, uncrewed aerial vehicles
(UAVs), vehicle-to-everything (V2X) communication, intelligent
transportation systems, and swarm robotics) have also served to
exacerbate security and privacy challenges and thus require urgent
attention from academia, industry, and policy-makers. To meet this
critical need, VehicleSec aims to bring together an audience of
university researchers, scientists, industry professionals, and
government representatives to contribute new theories, technologies,
and systems on any security/privacy issues related to vehicles (e.g.,
ground, aerial, in/on water, space), their sub-systems (e.g.,
in-vehicle networks, autonomy, connectivity, human-machine
interfaces), supporting infrastructures (e.g., transportation
infrastructure, charging station, ground control station), and related
fundamental technologies (e.g., sensing, control, AI/ML/DNN/LLM,
wireless communication, real-time computing, edge computing, location
service, simulation, digital twin, multi-agent protocol/system design,
and human-machine interaction).
Demo/Poster Session
VehicleSec will feature a demo/poster session to allow academic,
governmental, and industry participants to share demonstrations and/or
present posters of their latest practical attacks, defenses, and
security/privacy tools or systems related to vehicles.
Tutorial Session
The symposium will also feature a tutorial session with an in-depth
learning experience on one or more state-of-the-art topics in vehicle
privacy and security presented by researchers or practitioners within
the field. A tutorial should focus on its topic in detail and include
references to the "must-read" papers or materials within its
domain. Tutorials in which participants actively engage in exercises
or hands-on work are particularly welcome. We encourage tutorials to
include hands-on elements, live demonstrations, or interactive
discussions. Each tutorial will be allocated a one-hour
slot. Proposals should clearly indicate the format of the tutorial,
prerequisites for participating in the tutorial (e.g., background
knowledge, program languages), required materials (e.g., hardware,
datasets, virtual machine images, wifi access), including (if any)
material provide d by the applicant (e.g., hardware, documentation).
Lightning Talks Session
The symposium will feature a Lightning Talks session with short and
engaging 5-minute in-person presentations on any topics that can be
worth a timely shout-out to the VehicleSec community, which include
but are not limited to emerging hot topics, preliminary research
results, practical problems encountered, lessons learned, the
introduction of tutorials and education materials, tips and tricks,
simulators/simulations, data and visualizations (e.g., autonomous
driving datasets), or other (interdisciplinary) topics related to
vehicles.
Awards
Accepted papers and demos/posters will be considered for Best Paper
Award and Best Demo Award. Accepted artifacts will be considered for
the Distinguished Artifact Award.
Areas of Interest
Topics of interest include, but are not limited to:
Embedded/sensor/analog/actuator security, privacy, and forensics
in vehicle settings
Vehicle-related malware/firmware analysis
Secure/resilient/trustworthy/privacy-preserving perception,
localization, planning, and control in autonomous/automated
vehicles
Security/safety/robustness verification related to vehicles
Intra- and inter-vehicle network (e.g., CAN bus, V2X, remote
operator channel) security
Multi-vehicle coordination/cooperation (e.g., V2X, drone swarm) security
Compliance with policies (e.g., legal, security, privacy, safety,
and environmental policies)
Secure integration of hardware and software systems for vehicles
(e.g., ground, aerial)
Secure software/hardware updates in vehicle settings (e.g., cars,
drones, airplanes, spacecraft)
Privacy challenges in vehicle settings, (e.g., driver/passenger
privacy, drone/car/robot spying, intellectual property stealing,
etc.)
Privacy-preserving data sharing and analysis in vehicle settings
Security/privacy in electric, medium- and heavy-duty vehicle systems
Security/privacy in Intelligent Transportation Systems (ITS),
(e.g., intelligent traffic signals)
Security/privacy for vehicle-related supporting infrastructure
(e.g., charging)
Secure vehicle-related software/hardware development process
(e.g., debugging tools, simulators, testbed) and their own
security/privacy
Security/privacy of any vehicle-related fundamental technologies
(e.g., sensing, control, AI, location service, IoT, etc.)
Human factors, trust, humans in the loop, and usable security
related to vehicles
Security/privacy/resilience-related metrics and risk assessment for vehicles
GenAI-enabled attacks on vehicles and corresponding defensive approaches
GenAI tools and frameworks for the security of vehicles
Ethical Considerations
We expect authors to carefully consider and address the potential
harms associated with carrying out their research, as well as the
potential negative consequences that could stem from publishing their
work. Failure to do so may result in the rejection of a submission
regardless of its quality and scientific value. Where relevant, papers
should include a clear statement about why the benefit of the research
outweighs the harms and how the authors have taken measures and
followed best practices to ensure safety and minimize the potential
harms caused by their research. This includes but is not limited to,
considering the impact of your research on deployed systems,
understanding the costs your research imposes on others, safely and
appropriately collecting data, and following responsible
disclosure. Authors may wish to consult the USENIX Security '26 Ethics
Guidelines. Human Subjects Research
If your submitted document relates to human subjects, analyzes data
derived from human subjects, may put humans at risk, or might have
other ethical implications or introduce legal issues of potential
concern to the VehicleSec community, authors should disclose if an
ethics review (e.g., IRB approval) was conducted, and discuss in the
paper how ethical and legal concerns were addressed.
Vulnerability Disclosure
If your submitted document reports a potentially high-impact
vulnerability, the authors should discuss in detail the steps they
have already taken or plan to take to address these vulnerabilities
(e.g., by disclosing vulnerabilities to the vendors). The chairs will
contact the authors in case of concerns. The Program Committee
reserves the right to reject a submission if insufficient evidence was
presented that ethical or relevant legal concerns were appropriately
addressed.
Conflicts of Interest
Authors and Program Committee members are required to indicate any
conflict of interest and its nature. Advisors and those that they are
advising, as well as authors and PC members with an institutional
relationship, are considered to share a conflict of
interest. Professional collaborations (irrespective of whether they
resulted in publication or funding) that occurred in the past two
years and close personal relationships equally constitute a conflict
of interest. PC members, including chairs, who have a conflict of
interest with a paper will be entirely excluded from the evaluation of
that paper.
A Special Note on "Fake Conflicts": Declaring conflicts of interest to
avoid certain (otherwise non-conflicting) PC members is not allowed
and can constitute grounds for rejection. The PC Chairs reserve the
right to request additional explanation for any declared conflict. If
authors have concerns about the fair treatment of their submissions,
they should instead contact the chairs and provide convincing
arguments for any special consideration that they are requesting.
Acknowledgment
Final versions of accepted submissions should include all sources of
funding in an acknowledgments section. Authors should also disclose
any affiliations, interests, or other facts that might be relevant to
readers seeking to interpret the work and its implications. Authors
may wish to consider the 2026 IEEE S&P Financial Conflicts Policy for
examples.
AI Policy
What constitutes the use of AI is constantly evolving in the research
field. When using AI, and in their overall scientific process, authors
are expected to engage with respect and integrity when submitting to
VehicleSec: works submitted should constitute self-respecting work
that upholds the author's scientific values and personal dignity, that
respects the time and energy of reviewers, and respects the importance
of scientific inquiry and integrity.
Authors must carefully consider their decision to use generative AI
tools in their submission and appropriately disclose their use in a
separate and well-marked section in the body of the paper (the section
will count towards the page limit). Please consult the VehicleSec
Policy on the Use of Generative AI for the details.
Submission Guidelines for Papers
We accept (1) regular papers up to 13 pages and (2) short position
papers or work-in-progress (WIP) papers up to 6 pages, excluding
references and appendices. Short papers are suitable for position
papers or original works whose descriptions fit within 6 pages. WIP
papers are suitable for original yet incomplete work that is looking
for middle-stage feedback from the community. We also accept
Systemization of Knowledge (SoK) papers; the length of SoK papers
should be similar to regular papers. Note that reviewers are not
required to read the appendices or any supplementary material. Once
accepted, the camera-ready version of regular and SoK papers should be
at most 18 pages, and short position papers or work-in-progress (WIP)
papers should be at most 10 pages, including the bibliography and any
appendices. Authors should not change the font or the margins of the
USENIX format. For regular papers, shorter papers won't be penalized;
thus, authors are encouraged to submit papers of appropriate length
based on the research contribution.
Submissions should be typeset in two-column format using 10-point type
on 12-point (single-spaced) leading in a text block 7" wide x 9" deep,
with .33" inter-column space, formatted for 8.5" x 11" paper. Authors
must use the USENIX templates and style files when preparing their
paper for submission. Failure to adhere to the page limit and
formatting requirements can be grounds for rejection. Submissions must
be in Portable Document Format (PDF). Authors should pay special
attention to unusual fonts, images, and figures that might create
problems for reviewers. Documents should render correctly in Adobe
Reader when printed in black and white.
Submissions should be anonymized for review; no author names or
affiliations may appear on the title page, and papers should avoid
revealing authors' identities in the text. When referring to their
previous work, authors are required to cite their papers in the third
person without identifying themselves. Acceptance of final papers may
be subject to shepherd approval.
Short, WIP, and SoK papers must have their respective prefix
"Short:"/"WIP:"/"SoK:" in their titles and be submitted via the paper
submission form. Double and Concurrent Submissions
Technical papers must not substantially overlap with papers that have
been published or that are simultaneously submitted to a journal or a
conference/workshop with proceedings. Double-submission will result in
immediate rejection. The Program Committee may share information with
other conference chairs and journal editors so as to detect such
cases.
Submission and Publication Process
The program committee and external reviewers are required to treat all
submissions as confidential. However, the program co-chairs or
designated committee members may share submissions outside the program
committee to allow chairs of other conferences to identify dual
submissions. Papers that do not comply with the submission
requirements, including length and anonymity, or that do not have a
clear application to vehicle security and privacy may be rejected
without review. Papers accompanied by nondisclosure agreement forms
will not be considered.
Accepted submissions will be treated as confidential prior to
publication on the VehicleSec '26 website; rejected submissions will
be permanently treated as confidential.
As part of USENIX's open-access policy, all papers will be available
online before the conference. If your accepted paper should not be
published prior to the event, please notify production@usenix.org
after you submit your final accepted paper. USENIX also allows authors
to retain ownership of the copyright in their works, requesting only
that USENIX be granted the right to be the first publisher of that
work. See our sample consent form for the complete terms of
publication.
By submitting a paper, you agree that, if the paper is accepted, at
least one of the authors will register to attend the conference at
full price (i.e., not the student rate) and to present the paper;
USENIX members at the Sustainer level and higher may apply their
membership discounts to their registrations. If an author plans to
present more than one paper, one full-price registration will still be
required for each paper. If the conference registration fee will pose
a hardship for the presenter of an accepted paper, please contact
conference@usenix.org.
Alternative arrangements can be made if there are justifiable
difficulties in travel and will be allowed only on a case-by-case
basis with permission from the Program Co-chairs. The proceedings will
be published and archived by USENIX.
If you have any other questions related to the submission process,
please email the program co-chairs at
vehiclesec26chairs@usenix.org. Please reach out as soon as possible,
as it may not be possible to answer late questions prior to the
submission deadline.
Artifact Evaluation
A scientific paper consists of a constellation of artifacts that
extend beyond the document itself: software, hardware, evaluation data
and documentation, raw survey results, mechanized proofs, models, test
suites, benchmarks, and so on. In some cases, the quality of these
artifacts is as important as that of the paper itself. To emphasize
the importance of such artifacts, the benefits to the authors and the
community as a whole, and to promote the availability and
reproducibility of experimental results, VehicleSec '26 runs an
Artifact Evaluation. Authors of accepted papers are encouraged to
submit their artifacts for availability, functionality, and
reproducibility assessments. The Artifact Evaluation Committee (AEC)
will review each submitted artifact and also grant the Distinguished
Artifact Award to outstanding artifacts accepted to VehicleSec '26.
The Call for Artifacts will be available soon.
Submission Guidelines for Demos and Posters
We accept demos and posters of up to 2 pages, including references and
appendices. Submissions should be typeset in two-column format using
10-point type on 12-point (single-spaced) leading in a text block 7"
wide x 9" deep, with .33" inter-column space, formatted for 8.5" x 11"
paper. Authors must use the USENIX templates and style files when
preparing their demo and poster for submission. Submissions must be in
Portable Document Format (PDF). Authors should pay special attention
to unusual fonts, images, and figures that might create problems for
reviewers. Documents should render correctly in Adobe Reader when
printed in black and white.
Submissions can be anonymized for review, but it is not
mandatory. Demo and Poster papers must have the prefix "Demo:" or
"Poster:" in their titles and be submitted via the demos and posters
submission form.
To allow attendees to better learn and experience practical
vehicle-related attacks, defenses, and tools, VehicleSec will
structurally encourage authors to submit Demos. Specifically, all
accepted demos will be provided a demo table and a poster easel (so a
superset of the setup for an accepted Poster, which will be provided
only a poster easel). At the presentation time, each demo should have
(1) exhibitions, slides, videos, and/or interactive/live demos to
showcase on the table and (2) a poster presentation of the demo to be
put on the easel. All the accepted demos will be considered for the
Best Demo Award. Note that although at the presentation time, the
setup of a Demo includes a Poster, authors only need to submit a Demo
paper. For additional information regarding demos and posters, please
do not hesitate to contact the Demo/Poster Chair at
vehiclesec26-demos-posters@usenix.org. Submission Guidelines for
Tutorials
We invite tutorial proposals to be a part of the tutorial sessions
taking place during the symposium on August 10 and/or August 11,
2026. Tutorials aim to offer participants an in-depth and practical
understanding of emerging topics in vehicle security and privacy,
spanning research advancements, industry practices, and critical
policy issues. We welcome proposals from researchers, practitioners,
and educators in academia, industry, and government.
We encourage tutorials to include hands-on elements, live
demonstrations, or interactive discussions. Each tutorial will be
allocated in a one-hour slot. Proposals should clearly indicate the
format of the tutorial and required materials.
We accept tutorial submissions of up to 2 pages, including references
and appendices. Submissions should be typeset in two-column format
following the Demo/Poster layout (please see Submission Guidelines for
Demos and Posters above). Submissions can be anonymized for review,
but it is not mandatory. Tutorial submissions must have the prefix
"Tutorial:" in their titles and be submitted via the tutorial
submission form.
Tutorial proposals must include:
Title: A concise and descriptive title.
Abstract: A brief summary (up to 500 words) outlining the
tutorial's scope, objectives, and intended audience.
Presenter(s): Names, affiliations, and a short bio (a maximum of
250 words each) highlighting relevant expertise and experience.
Target Audience: Specify the expected audience, required prior
knowledge, and estimated number of attendees.
Content Outline: Detailed breakdown of topics to be covered and
expected learning outcomes.
Format and Duration: Proposed session length (one hour) and
preferred mode of delivery (e.g., lecture, hands-on, hybrid).
Special Requirements: Any technical or logistical needs (e.g.,
software, hardware, internet connectivity). Note that requirements
will be reviewed along with the submission, and if accepted,
submitters will be notified of what needs can and cannot be
fulfilled.
Supporting Material (optional): Any existing slides, reference
materials, or prerequisites that will be provided by the tutorial
presenters.
Tutorial proposals will be evaluated based on:
Relevance to the symposium themes.
Clarity and comprehensiveness of the proposal.
Practicality and accessibility of the tutorial content.
Presenter expertise and experience.
We encourage diversity in topics and presenters to provide
participants with a broad range of learning opportunities. For
additional information regarding tutorials, do not hesitate to contact
the Tutorial Chair at vehiclesec26-talks-tutorials@usenix.org.
Submission Guidelines for Lightning Talks
We solicit short and engaging 5-minute in-person lightning talk
presentations on any topics that can be worth a timely shout-out to
the VehicleSec community. These include but are not limited to:
emerging hot topics, work-in-progress research ideas and preliminary
results, practical problems encountered, lessons learned, tips and
tricks, simulators/simulations, data and visualizations (e.g.,
autonomous driving datasets), or other (interdisciplinary) topics
related to vehicles.
Note that the lightning talks are not intended for self-promotion or
commercial advertisement. Specifically, lightning talks share
concepts, methodologies, or findings that can be broadly applied or
spark meaningful discussions. Focus on the work itself rather than
promoting your product, service, or organization. Avoid sales pitches,
advertisements, or excessive emphasis on personal or corporate
achievements.
Please submit your Lightning Talk title and abstract (200 words or
less) for full consideration via the Lightning Talk submission
form. Lightning Talk abstracts will be published on the symposium
website.
All lightning talk submissions must include the presenter's name,
affiliation, and contact information. Please note that the presenter
must make all submissions. Submissions from PR firms will be rejected
without review. A time limit for lightning talks will be strictly
enforced. For additional information regarding Lightning Talks, do not
hesitate to contact the Lightning Talk Chair at
vehiclesec26-talks-tutorials@usenix.org.
Symposium Organizers
General Chairs
Hyungsub Kim, Indiana University
Aiping Xiong, The Pennsylvania State University
Program Co-Chairs
Sara Rampazzi, University of Florida
Ning Zhang, Washington University in St. Louis
Program Committee
Daniele Antonioli, EURECOM
MD Armanuzzaman, The University of Texas at El Paso
Luca Arnaboldi, University of Birmingham
Antonio Bianchi, Purdue University
Gedare Bloom, University of Colorado Colorado Springs
Divanilson R. Campelo, Universidade Federal de Pernambuco
Yulong Cao, NVIDIA
Stephen Checkoway, Oberlin College
Hanlin Chen, Oak Ridge National Laboratory
Yimin Chen, University of Massachusetts Lowell
Wonsuk Choi, Korea University
Andrew Clark, Washington University in St. Louis
Mauro Conti, University of Padova
Jiarun Dai, Fudan University
Jeremy Daily, Colorado State University
Pritam Dash, The University of British Columbia
Marco De Vincenzi, Institute of Informatics and Telematics (IIT), CNR
Bruce DeBruhl, California Polytechnic State University
Denis Donadel, University of Verona
Alessandro Erba, Karlsruhe Institute of Technology
Yiheng Feng, Purdue University
Thomas Forest, General Motors
Clement Fung, Carnegie Mellon University
Xing Gao, University of Delaware
Ryan Gerdes, Virginia Tech
Mohammad Hamad, Technical University of Munich
Hans-Joachim Hof, Technische Hochschule Ingolstadt
Bardh Hoxha, Toyota Research Institute of North America (TRINA)
Hongxin Hu, University at Buffalo
Shengtuo Hu, Palo Alto Networks
Murtuza Jadliwala, The University of Texas at San Antonio
Shalabh Jain, Center of Data for Public Good and University of Bangalore
Xiaoyu Ji, Zhejiang University
Justin Kappos, New York University
Ameer Kashani, DENSO International America, Inc.
Chung Hwan Kim, The University of Texas at Dallas
Huy Kang Kim, Korea University
Seulbae Kim, Pohang University of Science and Technology (POSTECH)
Taegyu Kim, The Pennsylvania State University
Yongdae Kim, Korea Advanced Institute of Science and Technology (KAIST)
Sebastian Köhler, The University of Manchester
Vireshwar Kumar, Indian Institute of Technology Delhi
Xiaojing Liao, University of Illinois Urbana–Champaign
Zhiqiang Lin, The Ohio State University
Peng Liu, The Pennsylvania State University
Stefano Longari, Politecnico di Milano
Li Lu, Zhejiang University
Tatsuya Mori, Waseda University
Ivan De Oliveira Nunes, University of Zurich
Habeeb Olufowobi, The University of Texas at Arlington
Muslum Ozgur Ozmen, Arizona State University
Christos Papadopoulos, The University of Memphis
Jonathan Petit, Qualcomm
Hanif Rahbari, Rochester Institute of Technology
Indrakshi Ray, Colorado State University
Amir Salarpour, Clemson University
Takami Sato, University of California, Irvine
Neetesh Saxena, Cardiff University
Shanghao Shi, Washington University in St. Louis
Yasser Shoukry, University of California, Irvine
David Starobinski, Boston University
Takeshi Sugawara, The University of Electro-Communications
Xi Tan, University of Colorado Colorado Springs
Nils Ole Tippenhauer, CISPA Helmholtz Center for Information Security
Yazhou Tu, Auburn University
Hrushikesh Varma, University of Florida
Jinwen Wang, The University of Texas at Dallas
Lan Wang, The University of Memphis
Ningfei Wang, Meta
André Weimerskirch, Block Harbor Cybersecurity
Yang Xiao, University of Kentucky
Luyi Xing, Indiana University
Kun Yang, Zhejiang University
Min Yang, Fudan University
Kentaro Yoshioka, Keio University
Ce Zhou, Missouri University of Science and Technology
Xugui Zhou, Louisiana State University
Yi Zhu, Wayne State University
Shuguo Zhuo, Zhejiang University
Saman Zonouz, Georgia Institute of Technology
Tutorial Co-Chairs
Ming Li, University of Arizona
Karthik Pattabiraman, University of British Columbia
Poster/Demo Program Co-Chairs
Habiba Farrukh, University of California, Irvine
Jinwen Wang, University of Texas Dallas
Poster/Demo Program Committee
Jiahao Cao, Tsinghua University
Noah T. Curran, University of Michigan
Mengyu Liu, Washington State University
Zeyan Liu, University of Louisville
Pedram MohajerAnsari, Clemson University
Marion Sudvarg, Washington University in St. Louis
Chenyi Wang, University of Arizona
Guangjing Wang, University of South Florida
Xinda Wang, The University of Texas at Dallas
Xiaoli Zhang, University of Science and Technology Beijing
Zhuangzhai Zhu, George Mason University
Publications Chair
Xiali Hei, University of Louisiana at Lafayette
Lightning Talks Co-Chairs
Marcio Juliato, Waymo
Mulong Luo, Florida State University
Publicity Co-Chairs
Nidhi Rastogi, Rochester Institute of Technology
Zhiyuan Yu, Texas A&M University
Sponsorship Co-Chairs
Mert Pesé, Clemson University
Qiben Yan, Michigan State University
Artifact Evaluation Committee Co-Chairs
Taegyu Kim, The Pennsylvania State University
Dario Stabili, University of Modena and Reggio Emilia
Artifact Evaluation Committee
Zain Ul Abideen, University of Idaho
Hassan El Alami, Howard University
Rohan Dilip Bhosle, Microsoft
Zheyun Feng, University of New Hampshire
Dimitri Galli, University of Modena and Reggio Emilia
Kamel Ghali, KAGE Corporation, Car Hacking Village
Avirek Ghatia, Salesforce
Ishaan Gupta, Google
Fan Huang, Indiana University Bloomington
Joseph Khoury, Louisiana State University
Nahyun Lee, Penn State University
Rao Li, Pennsylvania State University
Gianmarco Lusvardi, University of Modena and Reggio Emilia
Xingyu Lyu, University of Massachusetts Lowell
Naga Nithin Manne, Argonne National Laboratory
Jainta Paul, University of Utah
Ravi Chandra Sadineni, Google
Partho Sarthi, NVIDIA
Filip Valgimigli, University of Modena and Reggio Emilia
Connor Weyers, Indiana University Bloomington
Doguhan Yeke, Purdue University
Syed Mohammad Abbas Zaidi, NED University of Engineering and Technology
Ruixuan Zhang, New York University
Giovanni Gambigliani Zoccoli, University of Modena and Reggio Emilia
Steering Committee
Gail-Joon Ahn, Arizona State University
David Balenson, USC Information Sciences Institute
Chunming Qiao, University at Buffalo
Kang Shin, University of Michigan
Mani Srivastava, University of California, Los Angeles
Gene Tsudik, University of California, Irvine
Dongyan Xu, Purdue University