Small Scale Research Articles

DESIGN CONTROL SYSTEM OF MODULAR PRODUCTION SYSTEM DISTRIBUTION AND PICK AND PLACE STATION

The development of automation in the industry is accelerating rapidly. The presence of automation is a technology that is very helpful in increasing production. Automation cannot be separated from the existence of a control system to regulate or process an instruction or order. The Modular Production System is a station unit consisting of various types of stations that simulate production system designs on a small scale before being realized in real situations. The work process of the Modular Production System is controlled using a PLC. PLC needs to be programmed to manage the work process of the Modular Production System. The programming language commonly used in PLC programming is ladder diagrams. The existence of a control system on the Modular Production System using PLC will make the Modular Production System run automatically. It can communicate with other Modular Production Systems to become more efficient. Therefore this design discusses controlling the Modular Production System using a PLC with a ladder diagram. The distribution stations and pick and place stations are selected for the Modular Production System. With a control system on the Modular Production System distribution station and pick and place station, the Modular Production System can work automatically and communicate with each other between stations. The result of the design is an increase in the efficiency of the system cycle time and process accuracy.

The mediation role of innovation in the relationship between total quality management and performance of small and medium scale enterprises

PurposeThis study examined the mediation-moderation role of innovation and market dynamism in the association between total quality management (TQM) practices and the performance of small and medium-scale enterprises' (SMEs') performance with empirical evidence from sub-Saharan Africa.Design/methodology/approachUsing a questionnaire, the research model developed was tested with responses from 203 owners and managers of SMEs in Ghana. The analyses were done using Statistical Package for the Social Sciences (SPSS) and Smart Partial Least Squares Structural Equation Modeling (PLS-SEM).FindingsThe innovation initiatives partially and fully mediated the relationship between TQM practices and the performance of SMEs. Also, the indirect effect of TQM practices of SMEs on performance through innovation initiatives was negatively moderated by market dynamism.Practical implicationsThe study contributes to the TQM literature by validating the indirect and direct relationship between TQM practices and performance in the context of SMEs in a developing region.Originality/valueThis paper presents a novel understanding of the relationship between TQM and SMEs in developing regions of the world. The paper serves as a guide for SME owners and managers to improve the performance of their organizations through TQM practices.

From Powder to Pouch Cell: Setting up a Sodium‐Ion Battery Reference System Based on Na3V2(PO4)3/C and Hard Carbon

At the research level, novel active materials for batteries are synthesised on a small scale, fabricated into electrodes and electrochemically characterised using each group’s established process due to the lack of standards. Recently, eminent researchers have criticised the implementation of e.g. low active material contents/electrode loadings, the use of research‐type battery cell constructions, or the lack of statistically relevant data, resulting in overstated data and thus giving misleading predictions of the key performance indicators of new battery technologies. Here, we report on the establishment of a reference system for the development of sodium‐ion batteries. Electrodes are fabricated under relevant conditions using 9.5 mg/cm² self‐synthesised Na3V2(PO4)3/C cathode active material and 3.6 mg/cm² commercially available hard carbon anode active material. It is found that different types of battery cells are more or less suitable for half‐ and/ or full‐cell testing, resulting in ir/reproducible or underestimated active material capacities. Furthermore, the influence of electrode overhang, which is relevant for upscaling, is evaluated. The demonstrator cell (TRL 4‐5) has been further characterised providing measured data on the power/energy density and thermal behaviour during rate testing up to 15 C and projections are made for its practical limits.

Processes regulating local community assembly of plants and spiders in high latitude mountains

AbstractAimMountains are often used to study how environmental factors influence biodiversity. However, we have limited understanding of the processes causing biodiversity variation in mountains and whether such processes vary across trophic levels and spatial scales. The aim of this study was to evaluate (i) whether community assembly processes varied along elevational gradients, (ii) whether there were differences in such variation between primary producers (vascular plants) and secondary consumers (spiders) and (iii) whether there were scale dependencies in any elevational variation in community assembly.LocationFennoscandia, Northern Sweden.TaxonVascular plants, spiders.MethodsWe used phenotypic and phylogenetic dispersion to quantify how elevation influenced community assembly of vascular plants and spiders and whether there were any scale dependencies in such influences. Our original data of plant and spider communities came from our own field surveys, phenotypic dispersion was calculated based on matrices of ecological traits, and phylogenetic dispersion was calculated from phylogenetic trees for each organism group. Trait matrices were based on a combination of literature values and our own measurements. The phylogeny for vascular plants was based on a published plant super‐tree, whereas the phylogeny for spiders was created by ourselves based on the DNA sequences at the mitochondrial cytochrome c oxidase subunit 1 (COI).ResultsPlants were environmentally filtered throughout all elevations and scales, but the importance of convergent evolution increased with elevation. For spiders, the importance of environmental filtering as well as niche conservatism increased with elevation. For both groups, communities at smaller scales were more influenced by biotic regulation and niche conservatism than at larger scales.Main ConclusionsOur study highlights both taxonomic differences and scale dependencies in how elevation influences community assembly. We argue that these results can have broad ramifications for our understanding of how spatial variation in biodiversity is generated and maintained. This may have particular relevance for our ability to predict the ecological consequences of climate change. Our results further highlight that high elevation specialists may suffer increased risks of climate driven extinctions due to a combination of increased competition and increased fragmentation of suitable habitats. Particularly for spiders, which had high elevation specialists clustered along specific lineages, such extinctions could lead to significant loss of phylogenetic variation.

Digital Inclusive Finance and the Shadow Banking of Non-Financial Enterprises

In consideration of the macro background of guarding against diverting out of the real economy and the rapid development of digital inclusive finance, this study selects the A-share listed companies on the Shanghai and Shenzhen stock exchanges from 2011 to 2019 as samples to empirically investigate the impact of digital finance on the shadow banking of non-financial enterprises. The research finds that digital finance suppresses the expansion of shadow banking business scale in non-financial enterprises. Further examination reveals that the impact of digital finance development on the shadow banking of non-financial enterprises is mainly achieved through alleviating financing constraints and reducing financing costs. Heterogeneity tests indicate that the inhibitory effect of digital finance on non-financial enterprise shadow banking is more pronounced in companies with smaller scales, poorer information disclosure quality, and higher management expense ratios. Additionally, this inhibitory effect is primarily generated by the depth of digital finance development. This study provides empirical evidence and decision-making references to clarify the inhibition of shadow banking by digital finance and guide the development of digital finance.

How molecular architecture defines quantum yields

Understanding the intricate relationship between molecular architecture and function underpins most challenges at the forefront of chemical innovation. Bond-forming reactions are particularly influenced by the topology of a chemical structure, both on small molecule scale and in larger macromolecular frameworks. Herein, we elucidate the impact that molecular architecture has on the photo-induced cyclisations of a series of monodisperse macromolecules with defined spacers between photodimerisable moieties, and examine the relationship between propensity for intramolecular cyclisation and intermolecular network formation. We demonstrate a goldilocks zone of maximum reactivity between the sterically hindered and entropically limited regimes with a quantum yield of intramolecular cyclisation that is nearly an order of magnitude higher than the lowest value. As a result of the molecular design of trifunctional macromolecules, their quantum yields can be deconvoluted into the formation of two different cyclic isomers, as rationalised with molecular dynamics simulations. Critically, we visualise our solution-based studies with light-based additive manufacturing. We formulate four photoresists for microprinting, revealing that the precise positioning of functional groups is critical for resist performance, with lower intramolecular quantum yields leading to higher-quality printing in most cases.

Numerical investigation in an indirect concentrated solar thermal dryer incorporated with discrete mirrors

The objective of this study is to promote the production for small scale drying industries by reducing the drying time of agricultural products. Discrete mirrors are arranged in a parabolic fashion and used as reflectors to concentrate the incoming solar radiation. The available solar flux is doubled by using this discrete arrangement of mirrors. Optical simulations are performed using Monte Carlo Ray tracing algorithm and various effects were studied to select the best arrangement of mirrors. The concentrated type dryer has been numerically simulated and no-load testing is performed using ANSYS Fluent. Simulation is carried out for various inlet velocities from 0.1 to 1 m s−1. The concentrated setup operates between 0.4 and 1 m s−1 of velocity to obtain temperature in the range of 40–70 °C. The maximum and minimum increase in outlet temperature is 23.52% and 2.87%, and the Nusselt number enhancement is 18.94% and 4.15%, respectively.

Biological and fishery indicators for the small-scale marble crab fishery in Northern Patagonia: recommendations for improving a monitoring program and stock assessment of a data-limited fishery

Small-scale fisheries have been typically data-limited despite their economic importance for local communities. This is especially true in zones where fishing operations occur in remote areas under harsh weather conditions. Crab fishery in Chile is exclusively artisanal, and marble crab (Metacarcinus edwardsii) has the highest landing records. This species is found in most parts of the coast of Chile, but it is mainly caught in the south of the country (including Patagonia). Fishery management is data-limited, and monitoring has not established the spatial and temporal variability baseline necessary to determine its exploitation status. This fishery is currently evaluated annually under a scheme based on reporting biological and fishery information, primarily from the landing ports and secondarily from fishing grounds. In the present study, we collected data from fishing grounds on board artisanal fishing vessels around 45°S during an annual cycle to establish indicators based on catch per unit effort (above and below minimum legal size), size, sex ratio, and the relationship between weight and size. Our results showed that fishery and biological indicators respond more to seasonal patterns than to expected spatial heterogeneity related to different fishing grounds: proportional stock density (lowest in winter), sex ratio (biased toward males in winter), retained catch (highest in autumn), and released catch (highest in winter), while the average size of the largest 10% of the sample only showed differences between males and females. Additionally, released catch varied according to soak time, which indicates the effectiveness of escape rings incorporated in the traps. These results lead to recommendations related to the current monitoring program, which should include the selection of a limited number of fishing grounds standardized by season and the incorporation of information related to soak time and the presence of escape rings. Finally, this study highlights the importance of on-board scientific monitoring for any fisheries, even those of small scale.

Spatial patterns of Hyalomma marginatum-borne pathogens in the Occitanie region (France), a focus on the intriguing dynamics of Rickettsia aeschlimannii.

Hyalomma marginatum is an invasive tick species recently established in mainland southern France. This tick is known to host a diverse range of human and animal pathogens. While information about the dynamics of these pathogens is crucial to assess disease risk and develop effective monitoring strategies, few data on the spatial dynamics of these pathogens are currently available. We collected ticks in 27 sites in the Occitanie region to characterize spatial patterns of H. marginatum-borne pathogens. Several pathogens have been detected: Theileria equi (9.2%), Theileria orientalis (0.2%), Anaplasma phagocytophilum (1.6%), Anaplasma marginale (0.8%), and Rickettsia aeschlimannii (87.3%). Interestingly, we found a spatial clustered distribution for the pathogen R. aeschlimannii between two geographically isolated areas with infection rates and bacterial loads significantly lower in Hérault/Gard departments (infection rate 78.6% in average) compared to Aude/Pyrénées-Orientales departments (infection rate 92.3% in average). At a smaller scale, R. aeschlimannii infection rates varied from one site to another, ranging from 29% to 100%. Overall, such high infection rates (87.3% on average) and the effective maternal transmission of R. aeschlimannii might suggest a role as a tick symbiont in H. marginatum. Further studies are thus needed to understand both the status and the role of R. aeschlimannii in H. marginatum ticks.IMPORTANCETicks are obligatory hematophagous arthropods that transmit pathogens of medical and veterinary importance. Pathogen infections cause serious health issues in humans and considerable economic loss in domestic animals. Information about the presence of pathogens in ticks and their dynamics is crucial to assess disease risk for public and animal health. Analyzing tick-borne pathogens in ticks collected in 27 sites in the Occitanie region, our results highlight clear spatial patterns in the Hyalomma marginatum-borne pathogen distribution and strengthen the postulate that it is essential to develop effective monitoring strategies and consider the spatial scale to better characterize the circulation of tick-borne pathogens.

Efficient H2O2 Synthesis through a Two-Electron Oxygen Reduction Reaction by Electrocatalysts.

The two-electron oxygen reduction reaction (2e-ORR) for the sustainable synthesis of hydrogen peroxide (H2O2) has demonstrated considerable potential for local production of this environmentally friendly chemical oxidant on small, medium, and large scales. This method offers a promising alternative to the energy-intensive anthraquinone approach, placing a primary emphasis on the development of efficient electrocatalysts. Improving the efficiency of electrocatalysts and uncovering their catalytic mechanisms are essential steps in achieving high 2e-ORR activity, selectivity, and stability. This comprehensive review summarizes recent advancements in electrocatalysts for in-situ H2O2 production, providing a detailed overview of the field. In particular, the review delves into the design, fabrication, and investigation of catalytic active sites contributing to H2O2 selectivity. Additionally, it highlights a range of electrocatalysts including pure metals and alloys, transition metal compounds, single-atom catalysts, and carbon-based catalysts for the 2e-ORR pathway. Finally, the review addresses significant challenges and opportunities for efficient H2O2 electrosynthesis, as well as potential future research directions.

Influence of Sphagnum harvesting on arthropod fauna and vegetation with a focus on beetles (Coleoptera) and ants (Hymenoptera: Formicidae)

AbstractThe harvesting of living peat moss (Sphagnum spec.) for various industrial applications has become increasingly prevalent. The harvesting process involves manual or mechanical extraction of Sphagnum fragments with minor to significant alterations of the habitats. This study investigates the impact of Sphagnum harvesting on arthropod fauna and vegetation structure at two donor sites with small-scale Sphagnum harvest in northwestern Germany. In the first year after the harvest, comparative surveys were carried out between harvested and unharvested reference areas. Arthropods living in and on the upper Sphagnum layer were studied by manually extracting quadrat samples. Vegetation surveys focused on the vascular plant composition and Sphagnum layer thickness as key habitat parameters. Results indicate no substantial effects on the total numbers for most arthropod orders. In contrast, the frequency of ant workers and the number of ant nests were considerably lower in harvested areas compared to reference areas. Vegetation analysis revealed that the shortening of the Sphagnum hummocks led to a homogenization of the vegetation structure and alterations in species composition in favor of moisture-loving species. Although no significant effects on total beetle populations were observed, the abundance of bog generalists and specialists was significantly reduced in harvest areas. Certain species displayed preferences for harvested or reference areas. Future harvesting practices should consider preserving vulnerable arthropod species and restricting harvesting to a small scale to mitigate adverse effects on bog ecosystems.

Atlantic Meridional Overturning Circulation Decline: Tipping Small Scales under Global Warming.

The Atlantic circulation is a key component of the global ocean conveyor that transports heat and nutrients worldwide. Its likely weakening due to global warming has implications for climate and ecology. However, the expected changes remain largely uncertain as low-resolution climate models currently in use do not resolve small scales. Although the large-scale circulation tends to weaken uniformly in both the low-resolution and our high-resolution climate model version, we find that the small-scale circulation in the North Atlantic changes abruptly under global warming and exhibits pronounced spatial heterogeneity. Furthermore, the future Atlantic Ocean circulation in the high-resolution model version expands in conjunction with a sea ice retreat and strengthening toward the Arctic. Finally, the cutting-edge climate model indicates sensitive shifts in the eddies and circulation on regional scales for future warming and thus provides a benchmark for next-generation climate models that can get rid of parametrizations of unresolved scales.

Sustainable Light‐Assisted 3D Printing of Bio‐Based Microwave‐Functionalized Gallic Acid

AbstractThe development of 3D printing technologies and the requirement for more sustainable 3D printing materials is constantly growing. However, ensuring both sustainability and performance of the new materials is crucial to replace current fossil‐based polymers. Here, a bio‐based UV‐curable resin is produced in high yield from gallic acid (GA), a natural polyphenolic compound, by means of rapid and efficient microwave‐assisted methacrylation (5 min heating time and 10 min at 130 °C). The successful microwave‐assisted methacrylation with a high degree of substitution is confirmed by Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance spectroscopy. The radical UV‐photopolymerization of the methacrylated gallic acid (MGA) is further investigated by real‐time FTIR and differential scanning photo calorimetry (photo‐DSC) analyses, clearly demonstrating the high photo‐reactivity of MGA. Moreover, the %gel assessment demonstrates the formation of highly insoluble fractions after the UV‐curing, with 98% gel content. The photo‐rheology and rheology support the suitability of MGA for light‐assisted 3D printing. Indeed, a honeycomb and a hollow cube are 3D printed by means of the digital light processing 3D printing technique with high accuracy in a small scale. Finally, the cured‐MGA illustrates high Tg and thermal stability.

A decision methodology for site-level ecosystem accounting

The United Nations System of Environmental-Economic Accounting Ecosystem Accounting (SEEA EA) framework is the international standard for ecosystem accounting. To date, application of SEEA EA has been predominantly at large scales, usually at landscape and national levels. However, many environmental management decisions are taken locally, in site-specific contexts. While the use of SEEA EA continues to develop at all scales, there is currently no widely endorsed methodology for employing SEEA EA at local scales, such as the site level. We present a methodology for developing site-level ecosystem accounts, describing the important decisions at each step of the process. We also provide two case studies that demonstrate the context-dependent nature of the decision-making process of ecosystem accounting at small scales. The two major challenges for site-level accounting are stakeholder engagement and data availability. As the use of SEEA EA continues to increase in policy and decision-making processes worldwide, there is a need for local-scale case studies that adapt this methodology across a broad range of contexts. Our case studies provide some of the first published examples of the application of SEEA EA at the site level and are intended to promote consistent implementation of ecosystem accounting across scales.

High-throughput physiological phenotyping of crop evapotranspiration at the plot scale

ContextPlatforms and instrumentation for Field High-Throughput Plant Phenotyping (FHTPP) are well developed to measure important traits for crop breeding and agronomic studies. However, the research has focused on morphological and spectral traits; and approaches to estimate major physiological processes such as evapotranspiration (ET) for small experimental plots are lacking. ObjectiveIn this study, we put forward a new analytical framework to estimate plot-scale ET by integrating frequent phenotyping data (multispectral and thermal infrared images, canopy reflectance, and LiDAR point clouds) from a FHTPP system (known as NU-Spidercam), the weather data, a simplified two-source energy balance model, and reference ET and crop coefficient calculation. MethodsThe new plot-scale ET method was tested on five field experiments involving maize and soybean crops over two growing seasons, with the different treatment levels of irrigation water. Estimated plot-scale ET was accumulated across the growing reason for each plot, and its association with grain yield was investigated with regression analysis. ResultsThe result showed that plot-scale accumulated ET captured the seasonal trend of plot water use and clearly differentiated the irrigation treatments. Strong linear correlations were observed between plot-scale ET and grain yield, with R2 values ranging from 0.35 to 0.93 (average R2 = 0.71). Plot-scale ET appeared to be a more steady and stronger predictor of grain yield across the seasons than several other morphological and spectral traits including crop height, green pixel fraction, canopy temperature depression, and red-edge normalized difference vegetation index. ConclusionHigh spatial and temporal resolution of the field phenotyping data, along with the new analytical framework reported, successfully estimated ET at small plot scale, which is difficult to achieve with other systems or methods. SignificancesOur work of estimating ET at the plot-scale can be adopt to other ground-based platforms and drones, thus empowers physiologists, breeders, and agronomists for high-throughput phenotyping of water-use related traits and drought response evaluation.

Automated manufacture and experimentation of composite overwrapped pressure vessel with embedded optical sensor

In recent years, the mobility (air/land) industry has been developing fuel-cell vehicles for mass adoption as hydrogen technology matures. Compared to conventional metallic design, the composite overwrapped pressure vessel without a metal or polymer liner results in a lightweight solution for gaseous hydrogen storage which further improves fuel efficiencies. Since the capabilities of automated fiber placement for making multi-stiffened structures are distinct from other automated manufacturing techniques, this study aimed to evaluate the feasibility of implementing AFP into the manufacture of a small scale COPV with a partially composite liner. The manufacturing related challenges are identified and discussed. During the manufacturing process, Distributed fiber optic sensor was embedded between the plies, as a structural health monitoring solution, to monitor the mechanical performance of the pressurized tank. In addition, finite element study was done to predict the internal strains for different pressure levels and the measured experimental strains at the sensor's location are found to be in close agreement with the finite element results. It is shown that such sensors can be integrated into automated fiber placement manufactured tanks for internal strain monitoring.

Detecting dark matter substructures on small scales with fast radio bursts

Detecting dark matter substructures on small scales with fast radio bursts

ECOSENSE - Multi-scale quantification and modelling of spatio-temporal dynamics of ecosystem processes by smart autonomous sensor networks

Global climate change threatens ecosystem functioning worldwide. Forest ecosystems are particularly important for carbon sequestration, thereby buffering climate change and providing socio-economic services. However, recurrent stresses, such as heat waves, droughts and floods can affect forests with potential cascading effects on their carbon sink capacity, drought resilience and sustainability. Knowledge about the stress impact on the multitude of processes driving soil-plant-atmosphere interactions within these complex forest systems is widely lacking and uncertainty about future changes extremely high. Thus, forecasting forest response to climate change will require a dramatically improved process understanding of carbon and water cycling across various temporal (minutes to seasons) and spatial (leaf to ecosystem) scales covering atmosphere, biosphere, pedosphere and hydrosphere components. Many relevant processes controlling carbon and water exchange occur at small scales (e.g. rhizosphere, single leaf) with a high spatial and temporal variability, which is poorly constrained. However, interactions and feedback loops can be key players that amplify or dampen a system’s response to stress. Moreover, spatial and temporal scaling rules for these non-linear processes in structurally and functionally diverse ecosystems are unknown. Legacy effects, for example, altered response after previous stress and retarded recovery of forests after climate extremes, are not captured in state-of-the-art models. Currently, we are lacking the appropriate and interconnected measurement, data assimilation and modelling tools allowing for a comprehensive, real-time quantification of key processes at high spatio-temporal coverage in heterogeneous environments. Moreover, since climate impacts are highly unpredictable with respect to timing and location, future research will require novel mobile, easily deployable and cost-efficient approaches. ECOSENSE, therefore, assembles expertise from environmental and engineering sciences, both being excellently paired at the University of Freiburg. Our interdisciplinary research project will investigate all relevant scales in a next-generation ecosystem research assessment (ECOSENSE). Our vision is to detect and forecast critical changes in ecosystem functioning, based on the understanding of hierarchical process interaction. In the first phase, ECOSENSE will explore these process interactions by investigating pools and fluxes of water and carbon, i.e. CO2 exchange, isotope discrimination and volatile organic compounds (VOC), as well as stress indicators by remotely and in situ sensed chlorophyll fluorescence. To address these research tasks, ECOSENSE will develop, implement and test a distributed, autonomous, intelligent sensor network, based on novel microsensors tailored to the specific needs in remote and harsh forest environments. They will measure the spatio-temporal dynamics of ecosystem pools and fluxes in a naturally complex structured forest system with minimal physiological impact. Measured data will be transferred in real-time into a sophisticated database, which will be explored for process analysis, conducted by Artificial Intelligence and close to real-time process-based ecosystem models for now- and forecasting applications. Thereby, ECOSENSE will: i) break new ground for integrative ecosystem research by identifying hierarchies and interactions of abiotic and physiological processes of forest carbon and water exchange, ii) provide a profound understanding of complex ecosystem responses to environmental stressors and iii) enable the prediction of process-based alterations in ecosystem functioning and sustainability. Our novel ECOSENSE toolkit, tested and validated in controlled climate extreme experiments and our ECOSENSE Forest, will open new horizons for rapid assessment in vast and remote ecosystems. Thereby, ECOSENSE will allow for a unique avenue of data acquisition and, consequently, for unprecedented scale-crossing ecosystem understanding and modelling.

Non-symbolic estimation of big and small ratios with accurate and noisy feedback.

The ratio of two magnitudes can take one of two values depending on the order they are operated on: a 'big' ratio of the larger to smaller magnitude, or a 'small' ratio of the smaller to larger. Although big and small ratio scales have different metric properties and carry divergent predictions for perceptual comparison tasks, no psychophysical studies have directly compared them. Two experiments are reported in which subjects implicitly learned to compare pairs of brightnesses and line lengths by non-symbolic feedback based on the scaled big ratio, small ratio or difference of the magnitudes presented. Results of Experiment 1 showed all three operations were learned quickly and estimated with a high degree of accuracy that did not significantly differ across groups or between intensive and extensive modalities, though regressions on individual data suggested an overall predisposition towards differences. Experiment 2 tested whether subjects learned to estimate the operation trained or to associate stimulus pairs with correct responses. For each operation, Gaussian noise was added to the feedback that was constant for repetitions of each pair. For all subjects, coefficients for the added noise component were negative when entered in a regression model alongside the trained differences or ratios, and were statistically significant in 80% of individual cases. Thus, subjects learned to estimate the comparative operations and effectively ignored or suppressed the added noise. These results suggest the perceptual system is highly flexible in its capacity for non-symbolic computation, which may reflect a deeper connection between perceptual structure and mathematics.

Comparison of models for the warm-hot circumgalactic medium around Milky Way-like galaxies

ABSTRACT A systematic comparison of the models of the circumgalactic medium (CGM) and their observables is crucial to understanding the predictive power of the models and constraining physical processes that affect the thermodynamics of CGM. This paper compares four analytic CGM models: precipitation, isentropic, cooling flow, and baryon pasting models for the hot, volume-filling CGM phase, all assuming hydrostatic or quasi-hydrostatic equilibrium. We show that for fiducial parameters of the CGM of a Milky Way (MW)-like galaxy ($M_{\rm vir} \sim 10^{12}~{\rm M}_{\odot }$ at $z\sim 0$), the thermodynamic profiles – entropy, density, temperature, and pressure – show most significant differences between different models at small ($r\lesssim 30$ kpc) and large scales ($r\gtrsim 100$ kpc) while converging at intermediate scales. The slope of the entropy profile, which is one of the most important differentiators between models, is $\approx 0.8$ for the precipitation and cooling flow models, while it is $\approx 0.6$ and 0 for the baryon pasting and isentropic models, respectively. We make predictions for various observational quantities for an MW mass halo for the different models, including the projected Sunyaev–Zeldovich effect, soft X-ray emission (0.5–2 keV), dispersion measure, and column densities of oxygen ions (O vi, O vii, and O viii) observable in absorption. We provide Python packages to compute the thermodynamic and observable quantities for the different CGM models.