About

James Guest is a professor and the Hackerman Family Department Head of Civil and Systems Engineering at Johns Hopkins University. He holds a secondary appointment in the Department of Materials Science and Engineering and serves as the associate director of the Johns Hopkins Center for Additive Manufacturing and Architected Materials (JAM 2) and the Center for Integrated Structure-Materials Modeling and Simulation (CISMMS). Guest is an internationally recognized leader in the field of topology optimization, focusing on automating and enabling discovery in computational design processes. His research group develops algorithms for designing structures, devices, and architected materials applicable to infrastructure, energy, biomedical, and aerospace sectors. He has made fundamental advancements in design for manufacturability, design under uncertainty, and design for multifunctionality.

Research topics

• Computer Science
• Mathematics
• Algorithm
• Mathematical analysis
• Mathematical optimization
• Structural engineering
• Engineering
• Mechanical engineering
• Applied mathematics
• Electronic engineering
• Materials science

Selected publications

• To Quantize or Not to Quantize: Effects on Generative Models for Topology Optimization Problems

  Journal of Mechanical Design · 2026-03-19

  articleOpen access

  Abstract In topology optimization (TO) and related engineering applications, physics-constrained simulations are often used to optimize candidate designs given some set of design conditions. Such models can be computationally expensive and do not guarantee convergence to a desired result, given the frequent nonconvexity of design optimization problems. Creating data-driven approaches to warm-start these models—or even replace them entirely—has thus been an active area for engineering design researchers. In this article, we propose an augmented vector-quantized GAN (VQGAN) that allows for effective compression of TO designs within a discrete latent space, known as a codebook, while preserving high reconstruction quality. Further, we present a new dataset of two-dimensional heat sink designs optimized via multiphysics topology optimization (MTO) to train and evaluate this model. To concretely assess the benefits of the VQGAN quantization process, we conduct a latent analysis of its codebook as compared to the continuous latent space of a deep autoencoder (AE). We find that VQGAN can more effectively learn topological connections despite a high rate of data compression. Finally, we leverage the VQGAN codebook to train a small GPT-2 model that is capable of rapid generation of thermally performant heat sink designs. We show that the transformer-based approach is more effective than using a Wasserstein GAN with gradient penalty (WGAN-GP) due to its superior preservation of topological connections in MTO and similar applications.

  PublisherDOI

• To Quantize or Not to Quantize: Effects on Generative Models for Topology Optimization Problems

  Repository for Publications and Research Data (ETH Zurich) · 2026-04-29

  otherOpen access

  In topology optimization (TO) and related engineering applications, physics-constrained simulations are often used to optimize candidate designs given some set of design conditions. Such models can be computationally expensive and do not guarantee convergence to a desired result, given the frequent nonconvexity of design optimization problems. Creating data-driven approaches to warm-start these models-or even replace them entirely-has thus been an active area for engineering design researchers. In this article, we propose an augmented vector-quantized GAN (VQGAN) that allows for effective compression of TO designs within a discrete latent space, known as a codebook, while preserving high reconstruction quality. Further, we present a new dataset of two-dimensional heat sink designs optimized via multiphysics topology optimization (MTO) to train and evaluate this model. To concretely assess the benefits of the VQGAN quantization process, we conduct a latent analysis of its codebook as compared to the continuous latent space of a deep autoencoder (AE). We find that VQGAN can more effectively learn topological connections despite a high rate of data compression. Finally, we leverage the VQGAN codebook to train a small GPT-2 model that is capable of rapid generation of thermally performant heat sink designs. We show that the transformer-based approach is more effective than using a Wasserstein GAN with gradient penalty (WGAN-GP) due to its superior preservation of topological connections in MTO and similar applications.

  PublisherDOI

• A FUNDAMENTAL STUDY ON THE INFLUENCE OF PLASMA TREATMENT PARAMETERS ON THE ADHESIVE BONDING OF POLYETHERKETONEKETONE THERMOPLASTIC SUBSTRATES

  2025-09-09

  article

  The adoption of thermoplastic composites in aerospace applications is rapidly increasing, primarily due to their rapid processability, lightweight and recyclability. However, the effective bonding and joining of thermoplastic substrates is critical for the long-term sustainability of such materials within the aviation industry. Bonding thermoplastics using structural adhesives is challenging as they exhibit poor adhesion due to their low surface energy. Plasma treatment techniques have proven to be effective to permit the bonding of thermoplastics, however, repeatable bonding performance remains a concern, and a solution is needed. This paper provides a summary of work undertaken to investigate the influence of atmospheric plasma treatment variables and impact on the bonding of a carbon fiber supported polyetherketoneketone (PEKK) matrix using adhesives.

  PublisherDOI

• Computational Optimization of Director Patterns in Liquid Crystal Elastomers

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

• A Systematic Approach for Converting CAD Models to Voxel Representations for Efficient Topology Optimization

  2025-01-03

  articleSenior author

  Topology optimization is a design tool that is garnering significant attention in industry. This implementation paper seeks to inform the practicing engineering community on how topology optimization can be integrated in real-world design development processes. Specifically, we present a systematic computational geometry method, based on Boolean operations on convex solids, for converting arbitrary CAD solids and traction boundary conditions to structured and regular finite element meshes and load vectors. This enables us to use efficient geometrical multi-grid solvers and leads to memory and CPU-time savings. A collaborative workflow is presented where topology optimization is used to design the support structure within the skin of a UAV, adopting a topology optimization formulation of mass minimization with a compliance constraint. The methods in this paper are particularly useful in cases where some parts of the design domain are defined and precluded from changing, such as the skin geometry in the case of wing or turbine blade structural design.

  PublisherDOI

• Lessons Learned and Recommendations from a SCOPE Spinal Cord Injury Neurorestorative Clinical Trials Update

  Neurotrauma Reports · 2025-01-01 · 2 citations

  reviewOpen access

  considerations, prioritizing novelty and a focus on neurorestorative approaches. The sessions featured 13 speakers, covering 4 in-preparation, 4 in-progress, and 4 recently completed trials. In addition to in-person attendance, individuals worldwide viewed a live stream of the presentations. Approximately 1600 participants, comprising clinicians, researchers, industry stakeholders, foundations, and individuals with lived experiences, engaged in the CTU through both in-person and virtual channels. Presentations represented a variety of approaches, including drug, biological, and device-based therapeutics. This summary provides high-level summaries of the trials presented and the resulting discussions including lessons learned. Rather than recapitulating published data, the presentations and discussions emphasized the novelty and strengths of each trial, practical aspects of translation, and lessons learned. Throughout the day, several discussion themes surfaced. These included reflections on the suitability of outcome measures and the distinction between statistically or clinically meaningful effects and meaningful changes in quality of life. Additional topics included novel trial designs, selection of inclusion criteria, recognizing the indispensable role of rehabilitation, tailoring approaches to individual needs, the importance of integrating lived experience, and emphasizing the importance of establishing robust pre-clinical data packages before venturing into clinical translation. Importantly, strategic directives are summarized to address these challenges, focusing resources and efforts to steer forthcoming trials effectively.

  PublisherDOI

• Computational Optimization of Director Patterns in Liquid Crystal Elastomers

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Correlation Between Cardiovascular Remodeling and Cardiovascular Deficits Following Chronic Spinal Cord Injury

  Physiology · 2025-05-01

  article

  After spinal cord injury (SCI), cardiovascular remodeling occurs at multiple levels. Despite the high prevalence of cardiovascular disease following SCI, there are few studies that attempt to illustrate the interplay between cardiac structure and function following injury. This study aims to assess cardiovascular remodeling and its relationship to cardiovascular dysfunction following chronic cervical (C8) midline spinal contusion. Nineteen Sprague-Dawley rats either received C8 midline contusion (cSCI, n = 10; Infinite Horizon Impact Device; 250 kilodynes; 0 s dwell time) or laminectomy (LAM, n = 9) as sham control. Fifteen weeks post-surgery, echocardiography was performed to assess cardiac function and morphology. At week 16, rats were anesthetized by urethane and a blood pressure catheter was placed into the aortic arch via the left common carotid artery. Orthostatic stress testing was introduced to evaluate the cardiovascular responses during 3-minute 90 degrees head-up tilting, followed by pharmacological stress testing via norepinephrine (NE) infusion (i.v.) at low (1 µg/kg/min) and high (4 µg/kg/min) doses. After tissue collection, collagen content (Masson trichrome stain), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation (IC 100 stain), and sympathetic innervation (tyrosine hydroxylase stain) were next investigated in the cardiovascular tissues. Correlation analyses were also performed between cardiovascular structural and functional measures. Results demonstrated that cSCI rats became hypotensive at rest and 70% of cSCI rats experienced significant orthostatic hypotension with an inability to maintain heart rate (HR) during head-up tilting. HR and mean arterial pressure reactivity in response to high-dose NE infusion were also significantly decreased in cSCI rats ( p <0.05) compared to LAM rats. Echocardiographic results showed reduced left ventricular (LV) diameter and volume ( p <0.01). Additionally, histological results revealed increased LV collagen content ( p <0.001), number of ASC specks (p<0.05), and increased sympathetic nerve density and quantity, especially within the LV posterior wall ( p <0.01 and p <0.05, respectively). Moreover, a strong linear relationship between histopathological and cardiovascular functional measures was observed. Overall, this study demonstrates that cardiovascular dysfunction is strongly correlated with cardiac atrophy, myocardial fibrosis, cardiac inflammation that is in part mediated by the inflammasome in the form of ASC specks, and enhanced cardiac sympathetic activity following chronic C8 midline contusion. This study was supported by: NIH (R01 NS131493) and Florida Department of Health (COPBC). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

  PublisherDOI

• AO Spine Clinical Practice Recommendations for the Surgical Management of Acute Traumatic Spinal Cord Injury: Contemporary Concepts

  Global Spine Journal · 2025-06-08 · 6 citations

  reviewOpen access

  Study DesignReview of the literature with critical appraisal and clinical recommendations.ObjectiveTo highlight contemporary concepts relating to surgical care for acute traumatic spinal cord injury (SCI) based on recent evidence that may be integrated into clinical practice.MethodsThree recent articles relating to the surgical management of acute traumatic SCI were selected and critically appraised. Clinical practice recommendations were developed and graded as strong or conditional.ResultsArticle 1: Early vs late surgical decompression for central cord syndrome. Strong recommendation to consider early surgery (<24 hours) as an option in patients with ASIA Impairment Scale (AIS) grade C central cord syndrome. Article 2: Extent of decompression in motor complete SCI. Conditional recommendation to consider laminectomy, with or without anterior surgery, to achieve circumferential decompression of the spinal cord. Article 3: Use of intra-operative ultrasound. Conditional recommendation to use ultrasound intra-operatively to confirm the adequacy of surgical decompression.ConclusionsTimely and adequate decompression of the spinal cord are critical priorities in the management of acute traumatic SCI. The importance of timeliness extends to central cord syndrome. Careful consideration and use of operative techniques (e.g., addition of laminectomy) and adjuncts (e.g., intra-operative ultrasound) help achieve safe and adequate decompression of the spinal cord.

  PublisherDOI

• Morphogenetic Metals through Topology‐Driven Stiffness Changes and Electrochemical Activation

  Small · 2025-10-31

  articleOpen access

  Morphogenesis enables the adaptive capabilities of living organisms and has been realized in soft materials that heal, change stiffness, and grow. Metals, despite their importance, do not have the tools to enable morphogenesis near ambient temperatures because metal atoms require intense temperatures and energy to move. This paper reports a method for reversibly controlling the physical properties of metal lattices with minimal energy, power, and material input through electrochemically activated topology changes. Switching between two topological states in individual cells enables programmable material moduli between 1.1 MPa and 2.6 GPa. The room temperature electrochemical morphogenesis is reversible and provides in situ phase control of a vibrating mass. A topology optimization technique that solves for two extreme topologies with minimal change in part volume realizes metamaterials that switch between negative and positive Poisson's ratios. The presented approaches for changing mechanical properties through topology provide a new path for endowing metals with the adaptive characteristics of organisms.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Optimal Design of Flaw-tolerant Structures and Material Microarchitectures via Stochastic Topology Optimization

  NSF · $148k · 2014–2017

• Optimal Topology Design under Fabrication and Demand Uncertainties

  NSF · $360k · 2009–2013

• Design of 3D Woven Lattices with Optimized Damping Properties

  NSF · $650k · 2015–2019

• GOALI/Collaborative Research: Topology Optimization for Additively Manufactured Metal Castings

  NSF · $235k · 2015–2018

Frequent coauthors

• Seung‐Hyun Ha

  16 shared

• Cristopher D. Moen

  14 shared

• Timothy P. Weihs

  Johns Hopkins University

  13 shared

• Josephine V. Carstensen

  13 shared

• Payam Bahrami

  Optim Design (United States)

  11 shared

• Fodil Fadli

  Qatar University

  11 shared

• Sung Hoon Kang

  Johns Hopkins University

  10 shared

• May Thu Nwe Nwe

  Johns Hopkins University

  10 shared

Awards & honors

• Engineering Mechanics Institute Leonardo da Vinci award
• American Society of Civil Engineers Walter L. Huber Research…
• Inaugural Fellow of the International Society for Structural…
• Fellow of the American Society of Civil Engineers' Engineeri…