Vulcan: Multidisciplinary Research and Applications

• Vulcan is a multidisciplinary term representing diverse scientific concepts—from a disputed intra-Mercurial planet to exoplanet formation and advanced computational frameworks.
• It encompasses observational strategies in astronomy, rigorous dynamical tests for perihelion precession, and innovative models for inside-out planet formation.
• VULCAN also denotes robust open-source frameworks in atmospheric chemistry, high-energy experimental platforms, and advanced electrochemical catalyst supports.

Vulcan is a polysemous research term with distinct meanings across astronomy, planetary science, atmospheric chemistry, instrumentation, electrochemistry, and computer science. Historically, it denoted the hypothetical intra-Mercurial planet proposed to explain Mercury’s anomalous perihelion advance before General Relativity; in exoplanet formation, “Vulcan planets” are the innermost planets predicted by inside-out planet formation; in atmospheric science, VULCAN is an open-source kinetics code and later a 2D photochemical-transport framework; in observational and high-energy-density contexts, it names both the NASA Ames pre-Kepler Vulcan Project photometer and the Vulcan Petawatt laser; in electrochemistry, Vulcan XC-72 is a widely employed carbon-black support in gas diffusion electrodes; and in computing, VULCAN names several algorithmic systems for planning, optimization, and embodied manipulation (Lund, 2024, Chatterjee et al., 2014, Tsai et al., 2016, Socia et al., 2018, Krygier et al., 2015, Moura et al., 20 May 2025, Kuang et al., 26 Dec 2025).

1. The astronomical Vulcan hypothesis

In nineteenth-century celestial mechanics, Vulcan was the putative intra-Mercurial planet invoked by Urbain Le Verrier in 1859 after anomalous residuals in Mercury’s orbital elements were taken to imply an additional source of Newtonian perturbation. Lescarbault’s 1859 report of a dark body transiting the Sun, together with Radau’s circular-orbit fit with $a \simeq 0.1427$ AU, $P \simeq 19.7$ d, and maximum elongation $\pm 8^\circ$, gave the hypothesis an observational form, and subsequent decades saw sporadic claimed visual and eclipse-time sightings (Lund, 2024).

The hypothesis was progressively undermined by the maturation of photographic eclipse searches. By 1900–1908, expeditions targeted narrow, Sun-equatorial strips and captured no intramercurial body. Einstein’s General Relativity then supplied the extra perihelion advance of Mercury’s orbit without requiring any additional planet, eliminating the original dynamical motivation for Vulcan (Lund, 2024).

A modern historical reappraisal has asked whether an actual body could have escaped those early searches by occupying a different orbit from the one assumed by early twentieth-century observers. Two mechanisms are proposed in that context: a close-encounter scattering scenario involving the Great Comet of September 1882, and a von Zeipel–Lidov–Kozai mechanism under Mercury’s perturbations. In that treatment, the Kozai timescale is written as

$$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$

and with $P_{\rm Vulcan}\approx 19.7$ d, $P_{\rm Mercury}\approx 88.0$ d, and $e_{\rm Mercury}=0.206$, the resulting $T_{Kozai}\approx 368$ d is short enough that, over decades, a formerly equatorial orbit could have been tilted by many tens of degrees (Lund, 2024).

That reinterpretation also motivated eclipse-based search strategies broader than the historical $\pm 1^\circ$ equatorial strip. For the April 8, 2024 eclipse, the proposed observational configuration included paired high-dynamic-range, high-frame-rate imaging stations, a small solar coronagraph module, a fast CMOS camera behind a broad-band $500\text{–}600$ nm or narrow-band $P \simeq 19.7$0 nm Fe xiv filter, a sequence of exposure times from $P \simeq 19.7$1 ms to $P \simeq 19.7$2 s, and solar tracking with tip/tilt correction stabilized to $P \simeq 19.7$3 (Lund, 2024).

2. Modern dynamical tests, General Relativity, and primordial-black-hole variants

In modern orbital dynamics, Vulcan survives primarily as a falsifiable alternative to relativistic perihelion precession. One recent analysis compares two extraction methods for perihelion advance: rotation of the Laplace–Runge–Lenz vector and evolution of the perihelion longitude $P \simeq 19.7$4. For Mercury, Earth, and Mars the two methods agree to $P \simeq 19.7$5, whereas for asteroid Icarus the longitude-based method is corrupted by nodal “jitters,” while the Laplace–Runge–Lenz method remains consistent with Einstein’s formula

$P \simeq 19.7$6

This makes Icarus a particularly strong discriminator between relativistic and Vulcan-like explanations (Pogossian, 2 Jul 2025).

Within that framework, an optimized Newtonian Vulcan is placed at $P \simeq 19.7$7 AU with mass $P \simeq 19.7$8 kg. The resulting Newtonian+Vulcan perihelion advances are $P \simeq 19.7$9 for Mercury, $\pm 8^\circ$0 for Earth, $\pm 8^\circ$1 for Mars, and $\pm 8^\circ$2 for Icarus, compared with $\pm 8^\circ$3, $\pm 8^\circ$4, $\pm 8^\circ$5, and $\pm 8^\circ$6 in the GR model. The purely Vulcan contribution to Icarus is $\pm 8^\circ$7, whereas the purely relativistic contribution is $\pm 8^\circ$8, so Icarus experiences a $\pm 8^\circ$9 larger effect from this Vulcan than from GR (Pogossian, 2 Jul 2025).

The same work emphasizes parameter sensitivity. Small shifts $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$0 AU alter Mercury’s Newtonian advance by $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$1, a $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$2 mass shift changes Mercury’s precession by $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$3, and Icarus is even more sensitive, with $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$4 AU producing $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$5. Historically, Icarus’s anomalous precession carried uncertainties of $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$6, whereas current radar plus optical campaigns reach $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$7, and the projected precisions from Gaia-era astrometry and dedicated radar ranging are $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$8 and $$T_{Kozai} =\frac{P_{\rm Mercury}^{2}}{P_{\rm Vulcan}} (1-e_{\rm Mercury}^{2})^{3/2},$$9, respectively (Pogossian, 2 Jul 2025).

A more radical variant recasts Vulcan as a primordial black hole of planetary mass. In that formulation, the proposed object has $P_{\rm Vulcan}\approx 19.7$0 and Schwarzschild radius $P_{\rm Vulcan}\approx 19.7$1 mm, making it optically invisible while still producing Newtonian perturbations. However, although such a PBH Vulcan can be tuned to give Mercury $P_{\rm Vulcan}\approx 19.7$2, its contributions to Venus, Earth, and Mars are too small: for the Le Verrier set, $P_{\rm Vulcan}\approx 19.7$3, $P_{\rm Vulcan}\approx 19.7$4, and $P_{\rm Vulcan}\approx 19.7$5, compared with relativistic values $P_{\rm Vulcan}\approx 19.7$6, $P_{\rm Vulcan}\approx 19.7$7, and $P_{\rm Vulcan}\approx 19.7$8 (Pogossian, 23 Jan 2025).

The dynamical conclusion is therefore asymmetrical. A suitably chosen Vulcan can be made to reproduce Mercury’s excess precession in isolation, but a single Vulcan consistent with Mercury generally overpredicts or underpredicts other inner-solar-system observables, and the Icarus test is especially constraining. This suggests that Vulcan now functions less as a candidate planet than as a benchmark countermodel against which relativistic orbital dynamics can be stress-tested (Pogossian, 2 Jul 2025, Pogossian, 23 Jan 2025).

3. Vulcan planets in inside-out planet formation

In exoplanet science, “Vulcan planets” denote the innermost planets in compact systems under the inside-out planet formation (IOPF) scenario. In this model, centimeter-sized pebbles drift inward and accumulate at the pressure trap associated with the dead-zone inner boundary (DZIB), where the disk midplane temperature falls below $P_{\rm Vulcan}\approx 19.7$9 K and the MRI shuts off. A planet forms at this trap, opens a gap, shifts the DZIB outward, and thereby enables sequential planet formation from the inside outward (Chatterjee et al., 2014).

The characteristic mass scale is set by gap opening. After eliminating the disk accretion-rate dependence through the DZIB condition, the first-planet scaling becomes

$P_{\rm Mercury}\approx 88.0$0

with only weak dependence on $P_{\rm Mercury}\approx 88.0$1, $P_{\rm Mercury}\approx 88.0$2, $P_{\rm Mercury}\approx 88.0$3, and $P_{\rm Mercury}\approx 88.0$4, and independence from $P_{\rm Mercury}\approx 88.0$5, $P_{\rm Mercury}\approx 88.0$6, and $P_{\rm Mercury}\approx 88.0$7. This linear $P_{\rm Mercury}\approx 88.0$8-versus-$P_{\rm Mercury}\approx 88.0$9 law is the central IOPF prediction for Vulcan planets (Chatterjee et al., 2014).

Because observations usually provide radii rather than masses, the theory was compared with data through Monte Carlo sampling of intrinsic density dispersion and Kepler detection biases. Using 629 Kepler multi-transit systems, the calculation drew $e_{\rm Mercury}=0.206$0 from log-normal fits in four mass bins, converted $e_{\rm Mercury}=0.206$1 to $e_{\rm Mercury}=0.206$2, and applied an SNR $e_{\rm Mercury}=0.206$3 detection cut based on the estimated CDPP and transit depth. The bias-filtered synthetic populations yielded $e_{\rm Mercury}=0.206$4, consistent with the observed $e_{\rm Mercury}=0.206$5 for the innermost Kepler planets identified as Vulcans (Chatterjee et al., 2014).

The normalization of the relation constrains disk microphysics. Matching the observed normalization favors relatively low viscosities in the inner dead zone, with $e_{\rm Mercury}=0.206$6. In this usage, Vulcan is therefore not a hypothetical missing planet near the Sun, but a category of innermost super-Earths whose masses and orbital radii encode the gap-opening and DZIB physics of protoplanetary disks (Chatterjee et al., 2014).

4. VULCAN in atmospheric chemistry and global transport

VULCAN is also an open-source, validated chemical-kinetics code for exoplanetary atmospheres. The original 1D implementation was constructed for gaseous chemistry from $e_{\rm Mercury}=0.206$7 to $e_{\rm Mercury}=0.206$8 K using a reduced C–H–O network with about $e_{\rm Mercury}=0.206$9 reactions, eddy diffusion to mimic atmospheric dynamics, and no photochemistry. Its governing continuity equation is

$T_{Kozai}\approx 368$0

and a typical 100-layer atmosphere requires several minutes to reach steady state (Tsai et al., 2016).

The code was validated against thermochemical equilibrium, against ARGO and other disequilibrium calculations, and against the hot-Jupiter models of HD 189733b and HD 209458b. Even with $T_{Kozai}\approx 368$1 reactions rather than the $T_{Kozai}\approx 368$2 used in the Moses et al. models, it reproduced the major disequilibrium trends, and its sensitivity analysis was used to revisit the quenching approximation, which remained accurate for methane but failed for acetylene because the disequilibrium abundance of $T_{Kozai}\approx 368$3 is indirectly controlled by the disequilibrium abundance of $T_{Kozai}\approx 368$4 (Tsai et al., 2016).

A later update extended VULCAN to C–H–N–O–S networks and photochemistry, and added advection transport, condensation, various boundary conditions, and temperature-dependent UV cross-sections. In that formulation, the photolysis rates are

$T_{Kozai}\approx 368$5

with a two-stream radiative-transfer treatment for the actinic flux. The updated model was validated for HD 189733b, Jupiter, and Earth, and then applied to WASP-33b, HD 189733b, GJ 436b, and 51 Eridani b, with particular emphasis on sulfur chemistry, quenching, and photochemical haze precursors (Tsai et al., 2021).

The framework was later generalized to VULCAN 2D, which solves the continuity equations on isobars with both vertical and horizontal transport: $T_{Kozai}\approx 368$6 The standard grid uses 64 longitude columns and a log-pressure domain from 200 bar to $T_{Kozai}\approx 368$7 bar, and each vertical column is advanced with a Rosenbrock stiff solver using asynchronous column-by-column updates (Tsai et al., 2023).

This 2D transport model was validated analytically and against pseudo-2D and GCM-based benchmarks, and it identified a transition near $T_{Kozai}\approx 368$8 mbar between regimes dominated by horizontal transport and vertical mixing. In applications to HD 189733 b and HD 209458 b, the model showed that global transport can erase some pseudo-1D limb asymmetries while enhancing others; in the carbon-rich HD 209458 b case with $T_{Kozai}\approx 368$9, $\pm 1^\circ$0 exhibits a pronounced morning-limb peak and generates $\pm 1^\circ$1 absorption only on the morning limb (Tsai et al., 2023).

5. Vulcan as an observational and high-intensity experimental platform

The NASA Ames pre-Kepler Vulcan Project used the Vulcan photometer, a 10 cm refractor at Lick Observatory with a $\pm 1^\circ$2 CCD field overlapping the eventual Kepler field. During $\pm 1^\circ$3 continuous days in summer 2003, it monitored $\pm 1^\circ$4 stars brighter than $\pm 1^\circ$5 mag with typical cadence $\pm 1^\circ$6 and photometric precision sufficient to time 11 hr-period eclipsing binaries to $\pm 1^\circ$7 s (Socia et al., 2018).

That archival baseline proved decisive for the contact binary KIC 9832227. The Vulcan primary eclipse time,

$\pm 1^\circ$8

differed from the previously proposed exponential-decay merger model by $\pm 1^\circ$9 days, corresponding to $500\text{–}600$0 minutes, a $500\text{–}600$1 discrepancy. Together with reinterpreted NSVS data, the Vulcan measurement forced rejection of the predicted early-2022 red nova merger (Socia et al., 2018).

In high-intensity laser–matter interaction, the Vulcan PW laser at the Central Laser Facility was operated with $500\text{–}600$2 J on target, $500\text{–}600$3 fs pulse duration, wavelength $500\text{–}600$4 nm, an $500\text{–}600$5 off-axis parabola, a $500\text{–}600$6 FWHM focal spot, and peak intensity $500\text{–}600$7. In a selective deuterium-ion target-normal sheath acceleration experiment, a cryogenic $500\text{–}600$8 layer was deposited on the rear of 10 $500\text{–}600$9 Au foils immediately before the shot (Krygier et al., 2015).

That configuration produced a beam with $P \simeq 19.7$00 deuterium ions in the observable spectral window, peak energy $P \simeq 19.7$01 MeV/nucleon, laser-to-deuterium-ion conversion efficiency $P \simeq 19.7$02 above $P \simeq 19.7$03 MeV/nucleon within $P \simeq 19.7$04, and a conservative estimate of total conversion efficiency $P \simeq 19.7$05. The result demonstrated species-selective TNSA on a multi-hundred-joule, sub-picosecond facility and established a practical route toward high-purity deuterium sources for neutron generation and related applications (Krygier et al., 2015).

6. Vulcan XC-72 in electrochemical advanced oxidation

In electrochemistry, Vulcan usually refers to Vulcan XC-72 carbon, one of the most widely employed carbon-black supports in gas diffusion electrodes for electrochemical advanced oxidation processes. In its as-received form it is an amorphous carbon with high electrical conductivity, a hierarchical network of primary particles of $P \simeq 19.7$06 nm diameter that aggregate into micrometer-sized agglomerates, micro- and mesopores, and a specific surface area typically in the range $P \simeq 19.7$07. In a GDE, it provides a conductive backbone, supports $P \simeq 19.7$08 diffusion to the triple-phase boundary, and, with commonly $P \simeq 19.7$09 wt % PTFE, forms a water-repellent gas diffusion layer that resists flooding (Moura et al., 9 Jun 2026).

A prominent modification is flower-like $P \simeq 19.7$10 on Vulcan XC-72. In one implementation, a $P \simeq 19.7$11 wt % $P \simeq 19.7$12 electrocatalyst was prepared by solvothermal synthesis of monoclinic $P \simeq 19.7$13 nanoflowers followed by wet impregnation onto Vulcan XC-72, and then hot-pressed with $P \simeq 19.7$14 wt % PTFE over a carbon cloth current collector. In $P \simeq 19.7$15 M $P \simeq 19.7$16 at pH 3 under $P \simeq 19.7$17 bar $P \simeq 19.7$18, the GDE accumulated $P \simeq 19.7$19, $P \simeq 19.7$20, and $P \simeq 19.7$21 $P \simeq 19.7$22 at $P \simeq 19.7$23, $P \simeq 19.7$24, and $P \simeq 19.7$25, respectively, with current efficiency stabilized at $P \simeq 19.7$26, representing 3.4×, 2.2×, and 1.4× improvements over bare Vulcan XC-72 and reducing specific energy consumption by ca. $P \simeq 19.7$27 (Moura et al., 9 Jun 2026).

The same electrode was applied to electro-Fenton and photoelectro-Fenton degradation of ciprofloxacin. With $P \simeq 19.7$28 mM $P \simeq 19.7$29, ciprofloxacin at $P \simeq 19.7$30 was $P \simeq 19.7$31 degraded within $P \simeq 19.7$32 min under EF, with $P \simeq 19.7$33, but slowed thereafter because of limited $P \simeq 19.7$34 regeneration. Under UV at $P \simeq 19.7$35 nm, PEF achieved complete removal in $P \simeq 19.7$36 min with $P \simeq 19.7$37 and $P \simeq 19.7$38, while TOC mineralization reached $P \simeq 19.7$39 with a Pt anode and up to $P \simeq 19.7$40 with a boron-doped diamond anode. LC-MS/MS and DFT Fukui indices located hydroxyl-radical attack on the piperazine and quinolone moieties, and ECOSAR indicated lower toxicity for dominant byproducts such as DP$P \simeq 19.7$41, DP$P \simeq 19.7$42, and DP$P \simeq 19.7$43 than for the parent antibiotic (Moura et al., 9 Jun 2026).

A related WO$P \simeq 19.7$44/Vulcan study examined acidic and alkaline ORR more generally. The composites showed monoclinic WO$P \simeq 19.7$45 nanoflowers anchored on Vulcan aggregates, a $P \simeq 19.7$46 increase in surface $P \simeq 19.7$47 and $P \simeq 19.7$48 groups relative to pristine Vulcan, and systematically lower contact angles with increasing WO$P \simeq 19.7$49 loading. Under RRDE in 1 M NaOH, $P \simeq 19.7$50 WO$P \simeq 19.7$51/Vulcan gave $P \simeq 19.7$52 over $P \simeq 19.7$53 V with $P \simeq 19.7$54; in acidic GDE operation at pH 3 and $P \simeq 19.7$55, $P \simeq 19.7$56 WO$P \simeq 19.7$57/Vulcan produced $P \simeq 19.7$58 $P \simeq 19.7$59 after $P \simeq 19.7$60 min with $P \simeq 19.7$61 and energy consumption $P \simeq 19.7$62 (Moura et al., 20 May 2025).

Vulcan XC-72 has also been used as the conductive backbone in a NaNbO$P \simeq 19.7$63@CeO$P \simeq 19.7$64-modified GDE for electro-Fenton degradation of paracetamol. In that system, the carbon scaffold provides high surface area, $P \simeq 19.7$65 network conductivity, and three-phase mass transport, while EPR spin-trapping at X-band $P \simeq 19.7$66 GHz quantified radical generation directly. At $P \simeq 19.7$67 V vs. Ag$P \simeq 19.7$68AgCl, the GDE produced $P \simeq 19.7$69 at $P \simeq 19.7$70; first-order degradation constants were $P \simeq 19.7$71 and $P \simeq 19.7$72, with TOC removal after $P \simeq 19.7$73 min of $P \simeq 19.7$74 for Pt and $P \simeq 19.7$75 for BDD (Fernandes et al., 8 Jun 2026).

7. VULCAN as a family of computational systems

In computer science and robotics, VULCAN is repeatedly used as the name of systems that couple structured interfaces, search, or learned models to difficult sequential decision problems. The referents are distinct, but they share an emphasis on decomposing intractable global objectives into tractable subproblems.

System	Domain	Representative result
VULCAN	Chance-constrained MDPs	Solved a CCMDP with over $P \simeq 19.7$76 states in 3 minutes (Ayton et al., 2018)
Vulcan	Steiner Tree Problem	Average ratio $P \simeq 19.7$77 vs. Classic $P \simeq 19.7$78 on 15 SteinLib instances (Du et al., 2021)
Multi-Agent Vulcan	Information-driven adaptive sampling	Located $P \simeq 19.7$79 more phenomena in tested scenarios (Olkin et al., 2024)
VULCAN	Iterative 3D object arrangement	$P \simeq 19.7$80 collision rate and $P \simeq 19.7$81 floating rate on 25 tasks (Kuang et al., 26 Dec 2025)
Vulcan	LLM-driven systems heuristics	Up to $P \simeq 19.7$82 cache and $P \simeq 19.7$83 tiering improvement (Dwivedula et al., 31 Dec 2025)

For chance-constrained planning, Vulcan is a Monte Carlo Tree Search algorithm for CCMDPs with concave, nondecreasing risk-bounding functions $P \simeq 19.7$84. Its key technical step is a per-history decoupling constraint based on sequence execution risk, which converts a globally coupled chance constraint into a sufficient local condition. The resulting solver runs tens to hundreds of times faster than linear-programming methods and over ten times faster than heuristic-based methods while maintaining mean suboptimality on the order of a few percent (Ayton et al., 2018).

For graph optimization, Vulcan is a learning-based system for the Steiner Tree Problem that combines a compact graph embedding with a double deep Q network. On synthetic RR, ER, and WS graphs up to 100 vertices it typically achieved approximation ratios $P \simeq 19.7$85, maintained ratio below $P \simeq 19.7$86 when trained on 30-vertex graphs and tested up to 150 vertices, and on 15 SteinLib instances reached average ratio $P \simeq 19.7$87 compared with $P \simeq 19.7$88 for the Classic baseline (Du et al., 2021).

For distributed information gathering, Multi-Agent Vulcan formulates adaptive sampling as a finite-horizon POMDP with mutual-information reward, introduces an admissible additive relaxation of the true multi-agent mutual information, and clusters agents into communication “bubbles” for joint A*-style search. Across standard MAPF maps and real-world bathymetric scenarios, it found $P \simeq 19.7$89 more unique phenomena than single-agent baselines and enabled each agent to locate its first unique phenomenon up to $P \simeq 19.7$90 faster (Olkin et al., 2024).

For embodied 3D manipulation, VULCAN is a tool-augmented, multi-agent object-arrangement system built on an MCP-based API, specialized visual tools, and planner–executor–evaluator role decomposition. On 25 complex object-arrangement tasks comprising 111 unit steps, it achieved collision rate $P \simeq 19.7$91, floating rate $P \simeq 19.7$92, plausibility $P \simeq 19.7$93, and consistency $P \simeq 19.7$94, outperforming Blender-MCP, BlenderAlchemy, and FirePlace on the reported metrics (Kuang et al., 26 Dec 2025).

For systems policy synthesis, Vulcan separates policy from mechanism through minimal Value-type and Rank-type interfaces and performs evolutionary search over LLM-generated code. On CloudPhysics cache clusters it matched or exceeded a suite of hand-designed baselines with a peak $P \simeq 19.7$95 improvement in miss-rate-reduction over FIFO relative to the best baseline on cluster $P \simeq 19.7$96, and in memory tiering it improved over ARMS by $P \simeq 19.7$97 on GUPS, $P \simeq 19.7$98 on GapBS-BC, and $P \simeq 19.7$99 on Silo-TPCC (Dwivedula et al., 31 Dec 2025).

A further robotics usage appears in indoor fire-disaster response, where VULCAN denotes a multi-agent cooperative navigation framework built around RGB-D, thermal, and mmWave sensing, VLM-based frontier assignment, and hazard-aware Fast Marching planning. That work extends Habitat-Matterport3D with smoke diffusion, thermal hazards, and sensor degradation, and shows that representative multi-agent baselines degrade substantially under fire conditions, with the reported CHE rising from $\pm 8^\circ$00 under normal conditions to values such as $\pm 8^\circ$01 for Greedy and $\pm 8^\circ$02 for Co-NavGPT in fire scenarios (Liu et al., 14 Apr 2026).

Across these usages, the name no longer refers to a single object or theory. It designates a set of historically and technically separate constructs: a discarded planet hypothesis, a planetary-formation category, an atmospheric-chemistry codebase, an instrument and a laser facility, a conductive carbon substrate, and multiple algorithmic systems. The commonality is therefore nominal rather than ontological; the significance of “Vulcan” depends entirely on disciplinary context.