Spaced Rings Research Articles

A Data-driven Search For Mid-infrared Excesses Among Five Million Main-sequence FGK Stars

Stellar infrared excesses can indicate various phenomena of interest, from protoplanetary disks to debris disks, or (more speculatively) techno-signatures along the lines of Dyson spheres. In this paper, we conduct a large search for “extreme” infrared excesses, designed as a data-driven contextual anomaly detection pipeline. We focus our search on FGK stars close to the main sequence to favor nonyoung host stars. We look for excess in the mid-infrared, unlocking a large sample to search in while favoring extreme IR excess akin to the ones produced by extreme debris disks (EDDs) and/or planetary collision events. We combine observations from ESA Gaia Data Release 3, the Two Micron All-Sky Survey, and the unWISE version of NASA’s Wide-field Infrared Survey Explorer (WISE), and create a catalog of 4,898,812 stars with G < 16 mag. We consider a star to have an excess if it is substantially brighter in the W1 and W2 bands than what is predicted from an ensemble of machine learning models trained on the data, taking optical and near-infrared information as input features. We apply a set of additional cuts (derived from the machine learning models and the objects’ astronomical features) to avoid false positives and identify a set of 53 objects, including one previously identified EDD candidate. The typical infrared-excess fractional luminosities we find are in the range 0.005–0.1, consistent with previous EDD candidates and potential planetary collision events.

Exploring the Intersection of Alien Megastructures and Multidimensional Spaces: A Comprehensive Review

The study of multidimensional alien megastructures offers an intriguing junction of sophisticated astrophysical ideas with the quest for extraterrestrial intelligence. This research examines the theoretical underpinnings, detection methods, and prospective consequences of megastructures like as Dyson spheres, Ringworlds, and stellar engines for exoplanetary habitability. We study the feasibility and observable signatures of higher-dimensional structures using notions from string theory and M-theory. Initial simulations of a 4D Dyson Sphere, 4D Ring World, and higher-dimensional stellar engines interacting with chosen exoplanets show encouraging findings for energy collection efficiency, structural stability, and habitability potential. Our findings indicate that sophisticated civilizations may use higher- dimensional technology to maximize energy management and habitat construction, opening up new pathways for identifying techno signatures and broadening our understanding of the universe. Future study should concentrate on creating more advanced models, enhancing detecting technologies, and investigating the real engineering issues that come with these ambitious constructions.

Background Contamination of the Project Hephaistos Dyson Spheres Candidates

Project Hephaistos recently identified seven M-dwarfs as possible Dyson Spheres (DS) candidates. We have cross-matched three of these candidates (A, B and G) with radio sources detected in various all-sky surveys. The radio sources are offset from the Gaia stellar positions by ∼4.9, ∼0.4 and ∼5.″0 for candidates A, B, and G respectively. We propose that Dust obscured galaxies (DOGs) lying close to the line-of-sight of these M-dwarf stars significantly contribute to the measured WISE mid-IR flux densities in the WISE W3 and W4 wave bands. These three stars have therefore been misidentified as DS candidates. We also note that with an areal sky density of 9 × 10−6 per square arcsecond, Hot DOGs can probably account for the contamination of all 7 DS candidates drawn from an original sample of 5 million stars.

Detectability of Solar Panels as a Technosignature

In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the ultraviolet-to-visible (UV-VIS) and in the near-infrared, within the wavelength range of a space-based flagship mission concept like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide the 2022 human energy needs with a land cover of ∼2.4%, and projecting the future energy demand assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope. Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the UV-VIS (0.34–0.52 μm), we find that several hundreds of hours of observation time are needed to reach a signal-to-noise ratio of 5 for an Earth-like planet around a Sun-like star at 10 pc, even with a solar panel coverage of ∼23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even with much larger populations than today, the total energy use of human civilization would be orders of magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev Type I civilization. Any extraterrestrial civilization that likewise achieves sustainable population levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization as imagined in the Fermi paradox may not exist.

Project Hephaistos – II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE

ABSTRACT The search for extraterrestrial intelligence is currently being pursued using multiple techniques and in different wavelength bands. Dyson spheres, megastructures that could be constructed by advanced civilizations to harness the radiation energy of their host stars, represent a potential technosignature, that in principle may be hiding in public data already collected as part of large astronomical surveys. In this study, we present a comprehensive search for partial Dyson spheres by analysing optical and infrared observations from Gaia, 2MASS, and WISE. We develop a pipeline that employs multiple filters to identify potential candidates and reject interlopers in a sample of five million objects, which incorporates a convolutional neural network to help identify confusion in WISE data. Finally, the pipeline identifies seven candidates deserving of further analysis. All of these objects are M-dwarfs, for which astrophysical phenomena cannot easily account for the observed infrared excess emission.

Enhancing the integrity of a buried gas pipelines: Investigating ruptures, explosions, and strengthening solutions

The present paper presents findings from a case study of a buried gas pipeline that ruptured, causing a gas cloud explosion and subsequent fire. The study aimed to identify the incident's cause and improve the pipeline's strength under specific conditions. The study measured the pipe's actual wall thickness and conducted stress analysis using analytical and finite element methods to assess its integrity under corrosion. It evaluated if the 20-inch pipeline near road crossings could withstand external forces.In conclusion, the research underscores the importance of accurately assessing the structural integrity of buried pipelines, especially under conditions of corrosion. It highlights the utility of finite element analysis in providing a more precise understanding of stress distribution and can aid in designing pipelines that are better equipped to withstand various external pressures.The investigation illustrates the importance of increasing the strength of buried natural gas pipelines, in the crossing road area and, for this purpose, it was proposed (in terms of novelty associated with the study) a solution consisting in introduction of the pipeline in protective sleeves fitted with spacer rings.

Application of the Thermodynamics of Radiation to Dyson Spheres as Work Extractors and Computational Engines and Their Observational Consequences

I apply the thermodynamics of radiation to Dyson spheres as machines that do work or computation and examine their observational consequences. I identify four properties of Dyson spheres that complicate typical analyses: globally, they may do no work in the usual sense; they use radiation as the source and sink of energy; they accept radiation from a limited range of solid angles; and they conserve energy flux globally. I consider three kinds of activities: computation at the Landauer limit; dissipative activities, in which the energy of a sphere’s activities cascades into waste heat, as for a biosphere; and “traditional” work that leaves the sphere, such as radio emission. I apply the Landsberg formalism to derive efficiency limits in all three cases and show that optical circulators provide an “existence proof” that greatly simplifies the problem and allows the Landsberg limit to be plausibly approached. I find that for computation and traditional work, there is little to no advantage to nesting shells (as in a “Matrioshka Brain”); that the optimal use of mass is generally to make very small and hot Dyson spheres; that for “complete” Dyson spheres, we expect optical depths of several; and that in all cases the Landsberg limit corresponds to a form of the Carnot limit. I explore how these conclusions might change in the face of complications, such as the sphere having practical efficiencies below the Landsberg limit (using the endoreversible limit as an example), no use of optical circulators, and swarms of materials instead of shells.

Laminated Polymer‐Encapsulated Halide Perovskite Photoconductors

AbstractHerein, a simple, solvent‐free method to fabricate polymer‐encapsulated halide perovskite photoconductors is described. Dry mechanochemical synthesis is used to prepare CsPbBr3 in the presence of poly(butyl methacrylate) (PBMA). The resulting composite powder is then heated and pressed into a free‐standing disk with a thickness controlled by a metallic spacer ring. The disk can be laminated on a glass substrate patterned with interdigitated electrodes, resulting in a planar photoconductor device. The best photoconductive performance is obtained for disks that consist of 75 wt.% CsPbBr3 in PBMA, reaching a detectivity of ≈2 × 1011 Jones. Moreover, by adjusting the thickness of the disk, narrowband detectors can be obtained due to charge collection narrowing. Depending on the thickness of the pressed disk, the position and width of the detectivity peak can be tuned. At last, the disks are tested as possible absorber materials for X‐ray detectors, where ow detection limit, and fast and linear response are measured for perovskite‐polymer disks with 50 wt.% perovskite content. This work shows a simple and versatile approach toward the fabrication of halide perovskite photodetectors, which can be carried out in air and without the use of solvents.

Evaluation of the Ethos synthetic computed tomography for bolus-covered surfaces

PurposeEthos allows online adaption of radiotherapy treatment plans. Dose is calculated on synthetic computed tomographies (sCT), CT-like images generated by deforming planning CTs (pCT) onto daily cone beam CTs (CBCT) acquired during treatment sessions. Errors in sCT density distribution may lead to dose calculation errors. sCT correctness was investigated for bolus-covered surfaces. MethodspCTs were recorded of a slab phantom covered with bolus of different thicknesses and with air gaps introduced by spacer rings of variable diameters and heights. Treatment plans were irradiated following the adaptive workflow with different bolus configurations present in the pCT and CBCT. sCT densities were compared to those of the pCT for the same air gap size. Additionally, the neck region of an anthropomorphic phantom was imaged using a plane standard bolus versus an individual bolus adapted to the phantom’s outer contour. ResultsVarying bolus thickness by 5 mm between pCT and CBCT was reproduced in the sCT within 2 mm accuracy. Different air gaps in pCT and CBCT resulted in highly variable bolus thickness in the sCT with a typical error of 5 mm or more. In extreme cases, air gaps were filled with bolus material density in the sCT or the phantom was unrealistically deformed near changed bolus geometries. Changes in bolus thickness and deformation also occurred in the anthropomorphic phantom. ConclusionsCTs must be critically examined and included in plan-specific quality assurance. The use of tight-fitting air gap-free bolus should be preferred to increase the similarity between sCT and CBCT.

Uniform temperature field in panel radiators using modified spacer rings

This article describes the development of the best possible prototype panel radiator spacer ring using mathematical modelling. It is shown for the first time in the literature that this smallest part of the radiators has a very important function of distributing water in the upper distribution chamber of the radiator. This research brings new knowledge to the field of water flow in the radiator, which is fundamentally affected by the holes located radially in the spacer ring. On the basis of the experiment, the CFD model of the most commonly used spacer ring was validated. Various structural modifications of the spacer ring were investigated in order to achieve the most uniform distribution of the surface temperature along the length of the radiator plate. It was found that a wedge-shaped design solution most closely resembles this state. This patented solution represents the best possible way to ensure the most even distribution of the water in the radiator without changing the flow cross-section of the distribution chamber.

Investigation on characteristics and performance of bearing spacer ring

Bearings are widely used in the industry due to their ability to support the movement of rotating bodies. The spacer rings are a key component of double-row roller bearings; therefore, the characteristics and properties of the spacer rings have a significant impact on the bearing functions. However, the lack of the characteristics and performance analysis of the spacer ring limits the improvement of bearing performance. To analyze the characteristics of spacer rings and establish a basis for improving their performance, a new testing method for the characteristics and performance of the spacer ring was presented and corresponding experiments were developed. The test procedure entails the evaluation of basic characteristics, surface properties, and serviceability. Basic characteristics were determined through element testing and cross-section morphological observation; surface properties were assessed through surface morphology and surface roughness detection; and serviceability was identified by cross-section hardness and frictional wear tests. The results show that the proposed test method can comprehensively characterize the performance of the spacer rings. The spacer ring composition mainly contains Fe, Al, P, Si, Ca, and S, which contribute to excellent wear resistance, hardness, strength, and corrosion resistance. The cross-sectional morphology exhibits porous characteristics, which enhance lubricity. In terms of surface property, the surface of the spacer ring is relatively flat, and the surface roughness is generally less than 0.6 μm Sa. The average friction coefficient is 0.85, and the friction and wear properties of the spacer ring are good. This study contributes to establishing the testing and evaluation criteria for the performance of spacer rings in engineering, which helps to improve the performance of bearings.

Ultra-precision time-controlled grinding for flat mechanical parts with weak stiffness

High-precision flat mechanical parts are widely used, such as in aerostatic bearing, which requires a rather high machining precision. Due to large size, low stiffness and other machining problems, traditional ultra-precision grinding machine tool cannot directly achieve the final precision, so manual grinding is necessary to meet the manufacturing requirements, resulting in low efficiency. Based on the computer-controlled optical surfacing (CCOS) method and the flexible grinding process, the time-controlled grinding method (TCG) is proposed to achieve quantitative material removal at each position on the workpiece. Combined with the material removal mechanism, the removal function with good linearity and stability is extracted by controlling corresponding parameters. By applying a novel measuring and processing method of surface data with high precision and high efficiency, the flatness error and parallelism error are accurately obtained and used as grinding reference to carry out the time-controlled grinding experiment on one spacer ring with a diameter of 190 mm. The final flatness error converges from 1.5–2 μm to 0.6–0.7 μm and parallelism error converges from ~2 μm to ~0.6 μm, while the roughness converges from 273 nm Ra to 65 nm Ra, achieving the goal of ultra-precision digital machining of submicron level. The machining precision is better than traditional ultra-precision grinding machine tool, and the potential for time-controlled grinding method of ultra-precision machining in flat mechanical parts especially with low stiffness is verified.

Interstellar Objects from Broken Dyson Spheres

Without extensive maintenance, Dyson spheres inevitably disintegrate by asteroid impacts over billions of years. The resulting fragments would appear as anomalous interstellar objects, potentially sharing the unusual shape and motion of 1I/‘Oumuamua or the unusual material strength of the first two interstellar meteors, IM1 and IM2. If the Dyson sphere's tiles are light sails, the number of fragments could exceed that of interstellar asteroids because of their reduced escape speed from the star and the increase in stellar luminosity during the red giant phase.

Semi-Analytical Approach in BiER4BP for Exploring the Stable Positioning of the Elements of a Dyson Sphere

In this study, we present a new approach with semi-analytical and numerical findings for solving equations of motion of small orbiter m, which is moving under the combined gravitational attraction of three primaries, M1, M2, and M3, in case of the bi-elliptic restricted problem of four bodies (BiER4BP), where three such primaries, M1, M2, and M3, are moving on elliptic orbits with hierarchical configuration M3 &lt;&lt; M2 &lt;&lt; M1 within one plane as follows: third primary body M3 is moving on elliptical orbit around second M2, and second primary M2 is moving on elliptical orbit around first M1. Our aim for constructing the aforementioned quasi-planar motion of planetoid m is obtaining its coordinates supporting its orbit in a regime of close motion to the plane of orbiting the main bodies M1, M2, and M3. Meanwhile, the system of equations of motion was successfully numerically explored with respect to the existence and stable positioning of approximate solution for a Dyson sphere. As a result, the concept of the Dyson sphere for possible orbiting variety of solar energy absorbers was transformed to the elongated Dyson space net with respect to their trajectories for the successful process of absorbing the energy from the Sun; this can be recognized as symmetry reduction. We obtain the following: (1) the solution for coordinates {x, y} is described by the simplified system of two nonlinear ordinary differential equations of second order, depending on true anomaly f; (2) the expression for coordinate z is given by an equation of Riccati-type where small orbiter that quasi-oscillates close to the fixed plane {x,y,0}.

Design of impulsive asteroid flybys and scheduling of time-minimal optimal control arcs for the construction of a Dyson ring (GTOC 11)

This paper describes the approach used by the team named the Eccentric Anomalies to obtain the sixth best solution to the problem of the eleventh Global Trajectory Optimization Competition, whose futuristic scenario of Dyson sphere building remained mathematically relevant for current space mission design and engineering in general. As usual for this recurring challenge, it involved large-scale combinatorics at a high level and a multitude of optimal control problems at a lower level. Furthermore it proposed additional layers of complexity by adding a strong scheduling component to the usual flyby sequencing, and by featuring both impulsive and continuous-thrust trajectories. The authors took advantage of modern theoretical techniques and open-source tools to put together a sequential process including analysis based on analytical trajectory models, tree searches using efficient data structures, global and local finite-dimensional optimization and multi-objective trade-offs. The optimal control part was both tackled with direct transcription as well as indirect shooting methods, and the mixed-integer scheduling reformulated as a bi-level optimization. From a programming point of view, the main framework was set in an interpreted language whilst using as much as possible dependencies written in compiled ones for speed.

The Influence of Bearing Ring Inclination on Precision Ball Bearing Contact and Heat Generation Performance

The assembly quality between bearing components will lead to an increase in the load imbalance of each rolling element, which becomes a factor that affects the heat generation of precision bearings. The motion and heat generation of angular contact ball bearing (ACBB) under different assembly states were studied, and the quasi-static model of ACBB with outer ring tilting was established. The contact angle, contact load and motion posture of rolling elements were obtained. Then, the relative imbalance of the outer ring was experimentally simulated based on the outer spacer ring with poor end-parallelism, and the thermal characteristics of the spindle system were monitored. Through theoretical and experimental comparison, the influence of different skew degrees of rings on bearing heat generation and spindle rotation accuracy was discussed.

Dyson sphere building: On the design of the GTOC11 problem and summary of the results

The National University of Defense Technology and the Xi’an Satellite Control Center organized the 11th edition of the Global Trajectory Optimization Competition (GTOC11) in 2021. The GTOC11 problem was created as a link between the ninth and tenth editions of the Global Trajectory Optimization Competition to bridge the gap between the planetary and galactic civilizations by introducing an intermediate stellar civilization scenario. The problem involves the construction of a Dyson sphere, a theoretical mega-structure that encircles a star with platforms orbiting in a tight formation to capture the maximum energy from it. Challenges in astrodynamics including the construction-orbit selection, combinatorial flyby of multiple asteroids, and mass distribution among stations were considered in the Dyson sphere design. A total of 94 teams registered for the competition, of which 25 teams provided solutions and passed automatic verification on the website. In this article, we describe the selection of the problem and its design process. In addition, an overview of the entire competition and an analysis of its results are presented.

GTOC 11: Results from Tsinghua University and Shanghai Institute of Satellite Engineering

In this paper, the methods and results from Tsinghua University and Shanghai Institute of Satellite Engineering for the 11th Global Trajectory Optimization Competition (GTOC11) are presented. To deal with the complicated “Dyson Sphere” building problem, a three-stage procedure is conducted. First, the pre-analysis is performed to reduce search space. It is found that two-impulse maneuvers between asteroid flybys are near-optimal, the semi-major axis of the “Dyson Ring” should be better at 1.0–1.5 AU, and the larger arrival mass asteroids tend to be selected. Second, the globally optimal trajectory design problem is further divided into two sub-problems, the mothership trajectory design and the asteroid assignment to the “Dyson Ring” power stations. For the first problem, beam search is used to obtain numerous single mothership trajectories based on a pre-constructed flyby trajectory database of 3–8 asteroids. The overall trajectories and asteroids visited are obtained by selecting 10 mothership trajectories with a genetic algorithm. For the second problem, we build a database of optimal rendezvous times for all the 83,453 asteroids at different phase angles to reach power stations of different radii and phase angles, then a greedy algorithm is proposed to obtain the asteroid arrival schedule based on all the asteroids visited by motherships. Finally, local optimization of asteroid sequence and flyby epochs is conducted. The activation time adjustment in combination with indirect continuous-thrust trajectory optimization is used based on the global optimization result. In the final submission, motherships fly by 388 asteroids, and the minimum mass of twelve power stations reaches 94% of the theoretical upper bound, which is defined using the minimum-time orbital transfers with free initial and target phases.

The fellowship of the Dyson ring: ACT&Friends’ results and methods for GTOC 11

Dyson spheres are hypothetical megastructures encircling stars in order to harvest most of their energy output. During the 11th edition of the GTOC challenge, participants were tasked with a complex trajectory planning related to the construction of a precursor Dyson structure, a heliocentric ring made of twelve stations. To this purpose, we developed several new approaches that synthesize techniques from machine learning, combinatorial optimization, planning and scheduling, and evolutionary optimization effectively integrated into a fully automated pipeline. These include a machine learned transfer time estimator, improving the established Edelbaum approximation and thus better informing a Lazy Race Tree Search to identify and collect asteroids with high arrival mass for the stations; a series of optimally-phased low-thrust transfers to all stations computed by indirect optimization techniques, exploiting the synodic periodicity of the system; and a modified Hungarian scheduling algorithm, which utilizes evolutionary techniques to arrange a mass-balanced arrival schedule out of all transfer possibilities. We describe the steps of our pipeline in detail with a special focus on how our approaches mutually benefit from each other. Lastly, we outline and analyze the final solution of our team, ACT&Friends, which ranked second at the GTOC 11 challenge.

Infrared and optical detectability of Dyson spheres at white dwarf stars

ABSTRACT It has been hypothesized that advanced technological civilizations will construct giant space colonies and supporting infrastructures to orbit about their home stars. With data from recent satellites that operate at infrared and optical wavelengths (Spitzer, Wide-field Infrared Survey Explorer, Transiting Exoplanet Survey Satellite, Kepler), in company with a few modest assumptions, it is now possible to begin to constrain observationally the frequency of such space-based civilizations in our Milky Way Galaxy.