<p>This study investigates the impact of non-ideal instrumental effects on the performance of high-resolution Fourier Transform Infrared (FTIR) spectrometers, with a focus on the Bruker FTS 120M. Key non-idealities, including retroreflector misalignments, baseline drift, and spectral channeling, were systematically analyzed using advanced diagnostic tools such as ALIGN60 and LINEFIT. The nominal configuration exhibited significant anomalies, notably modulation efficiency (ME) deviations of up to <span class="inline-formula">+10.9 <i>%</i></span>, phase error (PE) variability of 2.11 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>−2</sup></span> radians, and spectral channeling frequencies such as a persistent 2.9044 cm<span class="inline-formula"><sup>−1</sup></span>, along with emerging frequencies around 0.24 cm<span class="inline-formula"><sup>−1</sup></span> attributed to retroreflector wear and CaF<span class="inline-formula"><sub>2</sub></span> beamsplitter degradation. A pronounced anomaly at 40.672 cm<span class="inline-formula"><sup>−1</sup></span>, likely induced by environmental factors such as external vibrations or mechanical instability, was also identified. Implementation of a modified configuration effectively addressed these issues, reducing PE variability to 0.042 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>−2</sup></span> radians, aligning ME within the NDACC-acceptable threshold of 1.1, and achieving substantial improvements in the instrument line shape (ILS), including sharper peaks, narrower full-width at half maximum (FWHM), and reduced sidelobe asymmetry. Analysis of HBr transmission spectra revealed improved fitting of the P(2) line, characterized by lower residuals and enhanced spectral quality. Simulated Haidinger fringes near zero path difference (ZPD) highlighted alignment degradation patterns, underscoring the necessity for precise optical adjustments. Temporal trends showed an increase in ILS peak height of <span class="inline-formula">>14 <i>%</i></span> associated with the instrument upgrade, together with significant mean absolute error (MAE) reductions achieved by the modified configuration. In addition, a targeted retrieval case study demonstrates that explicit propagation of the empirically characterized instrumental response into the forward model reduces spectral residuals and retrieval uncertainties while increasing the retrieved total column by approximately 6 %–7 % relative to the nominal configuration. Overall, this study provides a robust framework for diagnosing and correcting instrumental artifacts, ensuring the accuracy, reproducibility, and long-term stability of FTIR measurements essential for atmospheric trace gas retrievals.</p>
<p>This study systematically evaluated the quality of ionosphere-corrected bending angles from Fengyun3 (FY3) <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">D</mi><mo>/</mo><mi mathvariant="normal">E</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="8f2aa91624c9c59738e9e168ab021603"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-19-659-2026-ie00004.svg" width="23pt" height="14pt" src="amt-19-659-2026-ie00004.png"/></svg:svg></span></span> satellites (equipped with GPS and BDS receivers) using ERA5 data as references and MetOp products as comparisons. The quality of subsequent retrieved optimized bending angles, refractivity, and temperature were also analysed. Ionosphere-corrected bending angle were assessed via two approaches: outlier detection across 10–80 km and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>bias</mtext><mo>/</mo><mtext>noise</mtext></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="54pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="446f805ac264e5f3015fd50a785c7847"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-19-659-2026-ie00005.svg" width="54pt" height="14pt" src="amt-19-659-2026-ie00005.png"/></svg:svg></span></span> quantification. Overall quality evaluation showed that FY3 ionosphere-corrected bending angles were consistent with MetOp below 40 km. Above 40 km, FY3 bending angles exhibited larger errors than MetOp. In outlier detection, MetOp had less than 5 % bad profiles, followed by FY3D (<span class="inline-formula"><10 <i>%</i></span>), while FY3E (GPS/BDS) had about 20 % bad profiles. FY3E-GPS bending angles are prone to have large outliers in the height range of 35–50 km. For bias and noise quantification, the daily mean biases and noise levels of FY3 satellites were higher than those of MetOp. Specifically, FY3E-GPS showed notable large daily mean biases of about <span class="inline-formula">−0.4 µrad</span> and most of these biases are in setting RO events. FY3D and FY3E-BDS ranked second, with biases of approximately <span class="inline-formula">−0.1 µrad</span>. MetOp had the smallest biases, at around <span class="inline-formula">−0.05 µrad</span>. Regarding noises, FY3D, FY3E-GPS exhibited comparable noise levels, at roughly 2.5 <span class="inline-formula">µrad</span>; FY3E-BDS had lower noises of 1.5 <span class="inline-formula">µrad</span>. MetOp noises are smallest at about 1.0 <span class="inline-formula">µrad</span>. Due to the larger biases and noises at high altitudes, FY3's optimized bending angles were strongly corrected by background bending angles. Refractivity and temperature were also influenced by the strong correction of optimized bending angle. In summary, FY3 ionosphere-bending angles show high quality below 40 km. However, at high altitudes, further efforts are required for improving FY3 data's utility in numerical weather prediction and climate studies, especially for stratospheric applications.</p>
The metro depot, serving as the critical hub and maintenance center of urban rail transit systems. Its extensive scale, structural complexity, and fragmented information flows pose considerable challenges throughout the planning, construction, and operational management phases. This study aims to systematically develop and validate a comprehensive framework for the application of UAV-based oblique photogrammetry and 3D modeling throughout the entire lifecycle of metro depots.. The paper begins with an in-depth analysis of the complete technological pipeline of oblique photogrammetry, integrating both theoretical foundations and engineering practices, encompassing UAV selection criteria, flight planning, aerial triangulation algorithms, through to the generation of photorealistic textured 3D models using MultiView Stereo (MVS) matching and Poisson surface reconstruction. The study systematically demonstrates four key application values of this technology in metro depot environments.. First, during the planning and design phase, it enables rapid and precise topographic modeling and earthwork calculation, increasing efficiency by more than fivefold while maintaining errors within 3%. Second, during the construction phase, dynamic comparison between multi-temporal reality models with 4D BIM schedules facilitates transparent management of progress, quality, and safety. Third, for operational maintenance, it establishes a real-scene 3D-based platform for visual asset management and intelligent inspection. Fourth, it innovatively achieves deep integration of oblique photography models with BIM, GIS, 3D printing, and 720° VR, laying a solid data foundation for constructing the depot's Digital Twin. Validated through several flagship projects, this research conclusively positions UAV oblique photography as an indispensable core engine driving the digital and intelligent transformation of metro depots.
Hyoung-In Lee, Sang-Hyeon Kim, Tae-Yeon Kim
et al.
The structural vibration of industrial droplet dispensers can be modeled by telegraph-like equations to a good approximation. We reinterpret the telegraph equation from the standpoint of an electric–circuit system consisting of an inductor and a resistor, which is in interaction with an environment, say, a substrate. This interaction takes place through a capacitor and a shunt resistor. Such interactions serve as leakage. We have performed an analytical investigation of the frequency dispersion of telegraph equations over an unbounded one-dimensional domain. By varying newly identified key parameters, we have not only recovered the well-known characteristics but also discovered crossover phenomena regarding phase and group velocities. We have examined frequency responses of the electric circuit underlying telegraph equations, thereby confirming the role as low-pass filters. By identifying a set of physically meaningful reduced cases, we have laid the foundations on which we could further explore wave propagations over a finite domain with appropriate side conditions.
Atsushi Takao, Nobuyoshi Yabuki, Yoshikazu Otsuka
et al.
The productivity of the construction industry is about half that of the manufacturing industry, and the labor shortage in the construction industry is serious; therefore, improving productivity using information and communication technology (ICT) is an urgent issue. In addition, in civil engineering works, the number of projects that handle multiple types of soil and sand is increasing due to the recycling of construction waste soil; thus, traceability management is important to ensure quality. This paper presents a system that uses sensing on soil-transporting dump trucks and ICT to record which soil was piled up where with the aim of improving the efficiency of traceability management in earthwork construction. This system automatically creates traceability data by linking sensing data and data from the compaction management system via an application. This eliminates the need to record and manage the earthwork location, which was previously required manually to create traceability data, and reduces the labor and manpower required for traceability management. The created traceability data are automatically assigned attribute information such as the construction date and soil information; consequently, they can be used to check the construction history in the future.
In geotechnical engineering, it is crucial to make sure that the undrained shear strength (USS) of soft, sensitive clays is accurately assessed. The accuracy in forecasting USS is pivotal for ensuring the structural integrity and stability of foundations and earthworks. Addressing this concern, advanced data-driven NB techniques are utilized to disclose the complex interactions of USS with basic soil parameters. This paper presents a novel methodology for the USS prediction in soft clays using machine learning techniques, and particularly it highlights the attention on the following five important input variables: pre-consolidation stress (PS), vertical effective stress (VES), liquid limit (LL), plastic limit (PL), and natural water content (W). These are selected in view of their well-understood impact on the USS. This study reports an innovative effort to use SHO and AOSM for the model's hyperparameter tuning, reducing heuristic methods and computationally expensive brute-force searches. This will provide a neat methodology for improving accuracy in USS predictions and maintaining the optimality of the model performance. The results, therefore, provide geotechnical engineers and researchers with considerable benefits. They give a sound basis that is data-driven for the assessment of USS in soft sensitive clays and advance the safety and stability of civil engineering projects.
The performance of corrugated-wall steel silos for grain storage under complex geotechnical conditions depends significantly on the silo diameter and the height-to-diameter ratio. A key factor influencing foundation design is the vertical pressure exerted by the grain on the silo bottom, which increases with diameter. Based on pressure levels, all factory-made silos are divided into three groups: small (d = 11–16 m, 80–120 kPa), medium (d = 16–22 m, 120–160 kPa), and large (d = 22–28 m, 160–200 kPa). Each group demonstrates different performance characteristics under weak or collapsible soils. For the first group, natural subsoil or compacted soil cushions may be sufficient even under poor conditions. It has been established that for silos of the second group it is advisable to reinforce weak and subsiding soils or cut through them with pile foundations, especially for the bottom base, or to apply correctly substantiated calculation models of the joint operation of the components of the system “subsidence (weak) soil base – ring foundation – silo gallery – compacted base – bottom plate”. For the third group, construction on a unified foundation slab that supports the silo walls, bottom, and under-silo gallery is recommended. This solution ensures more uniform deformation and reduces the risk of operational problems. The results of surveys and numerical modeling confirm that the second group of silos is most prone to operational complications, especially if geotechnical control is not observed when compacting the backfill under the bottom. A set of recommendations is proposed that take into account the influence of the h/d ratio, the level of loads, and the type of soil base when choosing the type of foundations, which increases the reliability and durability of structures.
We propose two quantum experiments – modified Bell tests – that could detect contextual hidden variables underlying quantum mechanics. The experiments are inspired by hydrodynamic pilot-wave systems that mimic a wide range of quantum effects and exhibit a classical analog of contextuality. To justify the experiments, we show that contextual hidden variables are inevitable and ‘physics as usual’ if a unification between quantum mechanics and general relativity is possible. Accordingly, contextual theories can bypass Bell’s theorem in a way that is both local and non-conspiratorial. We end with a note on the relevance of exploratory experiments in the foundations of quantum physics.
The problem of soil swelling due to soaking is an important aspect of geotechnical analysis, especially in the design and construction of buried structures and foundations. In the conditions of Ukraine, where the creation of underground shelters is relevant, swelling soils create additional risks for the stability of structures. A separate threat is soil soaking, which can be caused by extinguishing fires during military operations. Studies of swelling clay soils have shown their orthotropy, which is manifested in a significant predominance of horizontal swelling over vertical - the difference can reach 60%. This causes not only an increase in the load on the foundation slabs, but also significant lateral pressure on buried structures. This feature of soils affects their deformation behavior, which must be taken into account when calculating the stability of buildings. Laboratory analysis of swelling confirmed the dependence of the degree of soil deformation on its initial humidity. A pattern has been observed, according to which soils with lower natural moisture content demonstrate a significantly higher swelling potential after soaking. This means that forecasting the moisture regime and preliminary analysis of hydrogeological conditions at the construction site are key factors in minimizing the risk of deformation and damage to structures. In the context of buried structures, it is necessary to consider not only vertical loads, but also possible lateral pressure on underground structures. This requires the implementation of additional structural measures aimed at strengthening the soils and increasing their stability. A thorough analysis of soil conditions, taking into account swelling factors and the use of effective methods of combating swelling will significantly reduce risks, ensure the durability of structures and their reliability of operation.
Due to the transition of modern buildings to the frame-monolithic scheme, buildings grow up and down. This increases the pressure on the foundations and leads to the need to solve nonlinear problems of soil mechanics in their design, since the main problem of technical systems is reliability. Recently, there has been a clear tendency to strengthen theoretical research in foundation engineering. Obtaining reliable modeling results in most cases is reduced to the use of nonlinear elastic-plastic models based on the theory of plastic flow, dilatancy relations of V.M. Nikolayevsky and I.P. Boyko. Domestic geotechnics is on the path of intensive development. Numerical methods based on elastic-plastic models are widely used. The destruction of discrete materials (including soil) occurs as a result of the accumulation of plastic (residual) deformations, which in the limiting state causes a break in the continuity of the massif in the form of mutual slippage of its particles. The effect of plasticity is manifested in the development of displacements and redistribution of internal forces. The strength of the bonds in dispersed soils is much lower than the strength of the particles themselves, and in the absence of adhesion forces (sand), the main factor of deformation of the soil base is the forces of contact interaction and deformation associated with repacking of particles. The main direction of development in construction is the use of new, rational and efficient pile designs that would increase their bearing capacity, manufacturability and installation. Low utilization of the material strength of square piles - low specific bearing capacity (25-60%) - hinders technical and economic progress in construction and requires the use of new efficient and rational pile designs. The introduction of piles with a complex cross-sectional shape is promising in this direction and is described in (Malyshev, 2011). Despite a considerable number of experimental studies of piles with complex cross-sectional shapes, there are few specific guidelines for their operation and calculation. The most efficient piles are cross-sectional, I-beam, and tavern piles. The least effective are round and square piles. It is also important to take into account and not to take into account the filling of the volume between the pile ribs with soil, since piles with a complex shape of the lateral surface (I-beam, I-beam, cross-shaped) have a different nature of soil compaction around their lateral surface and involve in their work some compacted soil zone that is formed between the pile ribs during their deepening, as noted in (Malyshev, 2011). Therefore, verification of the methodology for calculating the bearing capacity and deformation of the soil base by the numerical FEM of this type of piles, static vertical load, is an urgent task.
Perceptual Control Theory (PCT) and the Free Energy Principle (FEP) are two foundational, principle-based frameworks originally developed to explain brain function. However, since their initial proposals, both frameworks have been generalized to account for the behavior of living systems more broadly. Despite their conceptual overlap and practical successes, a mathematical comparison of the two frameworks has yet to be undertaken. In this article, we briefly introduce and compare the philosophical foundations underlying PCT and FEP. We then introduce and compare their experimental and mathematical foundations concretely in the context of bacterial chemotaxis. With these foundations in place, we can use tools from category theory to argue that PCT can be formally understood as a subset of the FEP framework; however, it is worth noting that the mathematical machinery unique to FEP is not required to successfully model bacterial chemotaxis. Finally, we conclude with a proposal for a mathematical synthesis where each framework plays an orthogonal yet complementary role.
The evaluation of the stress-strain state of shallow foundations, taking into account the heterogeneity and non-linearity of soil deformation and the requirements for ensuring the reliability and safety of the foundations using a probabilistic approach, allows the full use of the bearing capacity. The objective of this study is to improve the methodology for probabilistic analysis of the stress-strain state of foundations with a computational technique using random sampling, a validated non-linear method and computer programming. It is proposed to use probabilistic analysis to determine the allowable pressure in terms of both ultimate and serviceability limit states, namely ultimate bearing capacity, settlement exceedance and deformation. Calculations of square spread footings to support column loads on sandy and clay soils were carried out using both probabilistic and deterministic approaches. Probabilistic calculations yielded the following values of variation coefficients: ν(S)=0.06–0.17, ν(∆S/L)=0.74–0.79, ν(R)=0.08–0.14, ν(Pu)=0.10–0.18. In the case of heterogeneous soil mechanical properties with variation coefficients v ≥ 0.15 – 0.2, and with these variations taken into account in the probabilistic calculations, the allowable pressures on the footings did not exceed the calculated resistance as the limit of linearity. At higher pressures, the probability of soil failure also increases, and from the point at which 40-60 % of the bearing capacity is reached, it rises rapidly to values exceeding the allowable limits. According to the results of probabilistic analysis, the values of allowable pressures are 5-50 % lower than those obtained from deterministic calculations, which confirms the need to take into account the heterogeneity of soil characteristics, especially when assessing the possibility of the foundation's operation in the nonlinear stage of deformation due to their bearing capacity reserves.
M.O. Imanov, Bolotbek Temir, Kalamkas Abdrakhmanova
et al.
The problems associated with the suffusion compressibility of saline soils used in the construction of earthworks as foundations in flood conditions are considered. The author conducted studies of the effect of soaking, the amount and type of salts on the physical, deformation and filtration characteristics of soils. The results of the conducted research can be used for the design of engineering structures in flooded areas. Compressibility of saline soils of earthworks in conditions of flooding is an important aspect of geotechnical design and construction. Saline soils are characterized by increased density and reduced porosity, which can lead to significant changes in their compressibility when exposed to loads during flooding. Studies show that saline soils may be more susceptible to compressibility during prolonged soaking than conventional soils. Therefore, it is necessary to conduct special studies and calculations to assess the suffusion compressibility of saline soils in conditions of flooding and to take measures to prevent possible accidents. Thus, the study of the suffusion compressibility of saline soils of earthworks in conditions of flooding is an urgent and important task that requires special attention from geotechnical engineers and builders
Quang Tuan Nguyen, Bui Van Duc, Piotr Osiński
et al.
Slope failures due to erosion effect are a well-established cause of civil engineering structure disasters. Streams passing at the toe of a slope are a severe threat to geotechnical safety, especially in urbanized areas. To increase global safety, a retaining wall is usually proposed to limit the risk of failure. However, such works could also bring the high danger of a landslide during the construction works if not managed properly. The paper aims at investigating the collapse cause of residential buildings located at the edge of the slope at northwest part of Vietnam, where engineering works were performed to prevent failure due to soil erosion at the toe of the slope. During the retaining wall construction works, the applied excavation method caused significant vibrations and additional dynamic loads that could have affected the bearing capacity of the building foundations. Another cause of failure is associated with heavy precipitation recorded at the site just before the excavation works down the slope. The paper consists of numerical analyses allowing simulation of possible scenarios, including the effect of changing groundwater conditions using the meteorological data collected from the nearby monitoring weather station. The computations were performed using geotechnical software to reflect the in-situ conditions, and the entire process of earthworks performed at the site was carefully analyzed. The numerical analyses involved computations performed for a reinforced slope where a retaining wall was proposed to assure geotechnical safety of the remaining infrastructure after the failure.
<p>Upper-atmosphere winds from a meteor radar and a field-widened Michelson interferometer, co-located at the Polar Environment Atmospheric Research Laboratory in Eureka, Nunavut, Canada (80° N, 86° W) are compared. The two instruments implement different wind-measuring techniques at similar heights and have very different temporal and spatial observational footprints. The meteor radar provides winds averaged over a <span class="inline-formula">∼</span> 300 <span class="inline-formula">km</span> horizontal area in 3 <span class="inline-formula">km</span> vertical bins between 82 and 97 <span class="inline-formula">km</span> on a 1 <span class="inline-formula">h</span> cadence. The E-Region Wind Interferometer II (ERWIN) provides airglow-weighted winds (averaged over volumes of <span class="inline-formula">∼</span> 8 <span class="inline-formula">km</span> in height by <span class="inline-formula">∼</span> 5 <span class="inline-formula">km</span> radius) from three nightglow emissions (<span class="inline-formula">O(<sup>1</sup>S)</span>, oxygen green line, 557.7 <span class="inline-formula">nm</span>, 97 <span class="inline-formula">km</span>; an <span class="inline-formula">O<sub>2</sub></span> line, 866 <span class="inline-formula">nm</span>, 94 <span class="inline-formula">km</span>; and an <span class="inline-formula">OH</span> line, 843 <span class="inline-formula">nm</span>, 87 <span class="inline-formula">km</span>) on a <span class="inline-formula">∼</span> 5 <span class="inline-formula">min</span> cadence. ERWIN's higher precision (1–2 <span class="inline-formula">m s<sup>−1</sup></span> for the <span class="inline-formula">O(<sup>1</sup>S)</span> and <span class="inline-formula">OH</span> emissions and <span class="inline-formula">∼</span> 4 <span class="inline-formula">m s<sup>−1</sup></span> for the <span class="inline-formula">O<sub>2</sub></span> emissions) and higher cadence allows more substantive comparisons between winds measured by meteor radar and Doppler shifts in airglow emissions than previously possible for similar meteor radar/airglow Doppler shift comparisons using Fabry–Perot interferometers. The best correlation is achieved using Gaussian weighting of meteor radar winds with peak height and vertical width being optimally determined. Peak heights agree well with co-located SABER airglow observations. Offsets between the two instruments are <span class="inline-formula">∼</span> 1–2 <span class="inline-formula">m s<sup>−1</sup></span> for the <span class="inline-formula">O<sub>2</sub></span> and <span class="inline-formula">O(<sup>1</sup>S)</span> emissions and less than 0.3 <span class="inline-formula">m s<sup>−1</sup></span> for the <span class="inline-formula">OH</span> emission. Wind directions are highly correlated with a <span class="inline-formula">∼</span> <span class="inline-formula">1:1</span> correspondence. On average, meteor radar wind magnitudes are <span class="inline-formula">∼</span> 40 % larger than those from ERWIN. Gravity wave airglow brightness weighting of observations is discussed. Non-quadrature phase offsets between the airglow weighting and gravity wave associated wind and temperature perturbations will result in enhanced or reduced layer-weighted wind amplitudes.</p>
<p>Atmospheric turbulence parameters, such as turbulent kinetic energy and dissipation rate, are of great significance in weather prediction, meteorological disasters, and forecasting. Due to the lack of ideal direct detection methods, traditional structure function methods are mainly based on Kolmogorov's assumption of local isotropic turbulence and the well-known <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">5</mn><mo>/</mo><mn mathvariant="normal">3</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c010f45c8d9a823a56ed826ff72bac29"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-17-1837-2024-ie00001.svg" width="28pt" height="14pt" src="amt-17-1837-2024-ie00001.png"/></svg:svg></span></span> power law within the inertial subrange, which limits their application. Here, we propose a method for directly measuring atmospheric turbulence parameters using coherent Doppler wind lidar, which can directly obtain atmospheric turbulence parameters and vertical structural features, breaking the limitations of traditional methods. The first published spatiotemporal distribution map of the power-law exponent of the inertial subrange is provided in this study, which indicates the heterogeneity of atmospheric turbulence at different altitudes and also indicates that the power-law exponent at high altitudes does not fully comply with the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">5</mn><mo>/</mo><mn mathvariant="normal">3</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="fa0e74ec8cb07aa6650e6f2d65de63f0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-17-1837-2024-ie00002.svg" width="28pt" height="14pt" src="amt-17-1837-2024-ie00002.png"/></svg:svg></span></span> power law, proving the superiority of our method. We analyze the results under different weather conditions, indicating that the method still holds. The turbulent kinetic energy and power-law index obtained by this method are continuously compared with the results obtained with an ultrasonic anemometer for a month-long period. The results of the two have high consistency and correlation, verifying the accuracy and applicability of the proposed method. The proposed method has great significance in studying the vertical structural characteristics of atmospheric turbulence.</p>
<p>Fugitive methane (CH<span class="inline-formula"><sub>4</sub></span>) emissions occur in the whole chain of oil and gas production, including from extraction, transportation, storage, and distribution. Such emissions are usually detected and quantified by conducting surveys as close as possible to the source location. However, these surveys are labour-intensive, are costly, and fail to not provide continuous emissions monitoring. The deployment of permanent sensor networks in the vicinity of industrial CH<span class="inline-formula"><sub>4</sub></span> emitting facilities would overcome the limitations of surveys by providing accurate emission estimates, thanks to continuous sampling of emission plumes. Yet high-precision instruments are too costly to deploy in such networks. Low-cost sensors using a metal oxide semiconductor (MOS) are presented as a cheap alternative for such deployments due to their compact dimensions and to their sensitivity to CH<span class="inline-formula"><sub>4</sub></span>. In this study, we demonstrate the ability of two types of MOS sensors (TGS 2611-C00 and TGS 2611-E00) manufactured by Figaro<sup>®</sup> to reconstruct a CH<span class="inline-formula"><sub>4</sub></span> signal, as measured by a high-precision reference gas analyser, during a 7 d controlled release campaign conducted by TotalEnergies<sup>®</sup> in autumn 2019 near Pau, France. We propose a baseline voltage correction linked to atmospheric CH<span class="inline-formula"><sub>4</sub></span> background variations per instrument based on an iterative comparison of neighbouring observations, i.e. data points. Two CH<span class="inline-formula"><sub>4</sub></span> mole fraction reconstruction models were compared: multilayer perceptron (MLP) and second-degree polynomial. Emission estimates were then computed using an inversion approach based on the adjoint of a Gaussian dispersion model. Despite obtaining emission estimates comparable with those obtained using high-precision instruments (average emission rate error of 25 % and average location error of 9.5 m), the application of these emission estimates is limited to adequate environmental conditions. Emission estimates are also influenced by model errors in the inversion process.</p>