Engineering

Article
Engineering
Safety, Risk, Reliability and Quality

Nina Weinmann

,

Richard Kuracina

,

Zuzana Szabová

,

Maroš Soldán

,

Dominika Demeterová

Abstract: The explosive behaviour of combustible dust is strongly influenced by their physical and chemical properties. In the food-processing industry, flour dust represents one of the most common combustible materials capable of generating hazardous dust explosions. The objective of this study was to investigate the influence of flour type on explosion parameters and sensitivity to ignite. Three commercially available wheat flours with different compositions were examined: wheat flour 00 (T430), bread flour T650, and wholemeal flour T1800. Explosion characteristics, including maximum explosion pressure (pmax), maximum rate of pressure rise (dp/dt)max, and time parameters, were measured in a standardized 20 L sphere in accordance with EN 14034 Standard. The minimum ignition energy (MIE) was determined using a Hartmann tube apparatus according to EN 13821 Standard. All tested flour samples exhibited similar MIE intervals. The measured maximum explosion pressures ranged from 7.29 to 7.71 bar(g). However, differences were observed in the maximum rate of pressure rise. Significant differences were also identified in the time required to reach characteristic explosion parameters. The results demonstrate that flour type can significantly affect explosion parameters. These findings indicate that the selection of a representative flour sample is important for accurate hazard assessment and the design of effective explosion prevention and protection measures in the food-processing industry.

Article
Engineering
Bioengineering

Alfredo Bayu Satriya

,

Myles Joshua Toledo Tan

,

Yong-Kyu Yoon

,

Gloria Kim

Abstract: Radio-frequency (RF) reflection measurements provide a non-ionizing approach for estimating biological tissue thickness; however, accurately resolving deeper tissues is difficult because their reflections are attenuated and superimposed with those from overlying layers. This study presents a physics-guided stacked-regression framework for estimating subcutaneous adipose tissue (SAT), muscle tissue (MT), and visceral adipose tissue (VAT) thicknesses from simulated scattering parameters. A planar multilayer abdominal model containing 120 combinations of SAT, MT, and VAT thicknesses was evaluated. The input features consisted of the magnitude of S11 at ten frequencies from 300 MHz to 2 GHz, including four intermediate frequencies at 600, 700, 800, and 900 MHz that were absent from the previous model. Target-specific frequency subsets were selected and evaluated using polynomial regression and five-fold cross-validation. Multilayer reflection theory was used to explain the nonlinear relationship between tissue thickness and the measured RF response. The extended-frequency models achieved errors of 1.96%, 7.60%, and 19.86% for SAT, MT, and VAT, respectively, compared with 2.56%, 11.42%, and 39.10% in the previous model. A selective stacked architecture was subsequently evaluated by using an estimated overlying tissue thickness as an additional input for a deeper-tissue estimator. Adding predicted SAT thickness degraded MT estimation, whereas adding predicted MT thickness improved VAT estimation. The final stacked VAT model achieved an RMSE of 0.14±0.11 mm, an R2 of 0.97±0.02, and an error of 12.49%, corresponding to a 68.06% error reduction relative to the previous VAT model. These findings demonstrate that denser frequency sampling and selectively applied anatomical guidance can improve RF-based estimation of deeper tissue layers.

Article
Engineering
Energy and Fuel Technology

Volodymyr Derii

,

Artur Zaporozhets

,

Tetiana Nechaieva

,

Yaroslav Havrylenko

Abstract: Efforts to mitigate climate change have driven the decarbonization of the global economy, particularly the energy sector, accelerating the integration of renewable energy sources into power systems. However, the variability and limited predictability of wind and solar power generation increase flexibility requirements and may lead to renewable energy curtailment due to generation surpluses, grid constraints, and operational or market-related factors. Key mitigation measures include energy storage systems, hybrid energy complexes, interregional interconnections, demand-side management, and optimization of the generation mix. Unlike existing approaches that focus on optimizing individual system components according to economic or reliability criteria, this study investigates how the ratio of installed wind and solar capacities affects the power and energy capacity requirements of an energy storage system (ESS). The proposed approach normalizes actual hourly generation profiles to identify the capacity ratio that minimizes ESS requirements. A hybrid energy complex comprising wind and solar power plants and an ESS operating in parallel with the grid in baseload mode is analyzed using statistical and factor analysis, mathematical modeling, and computational methods. The results indicate that the optimal solar-to-wind installed capacity ratio ranges from 0.75 to 1.25. At a ratio of 1.0, the required ESS energy capacity decreases by 39-41%, while the required storage power decreases by 30–45%, compared with a standalone wind power plant. These findings demonstrate the potential to reduce energy storage system construction or leasing costs through optimal wind–solar capacity allocation.

Article
Engineering
Civil Engineering

Valentin Fogang

Abstract: The aim of this paper is the analysis of arbitrarily loaded isotropic rectangular Kirchhoff plates supported at all corner points, whereby the edges are arbitrarily supported (simply supported, clamped, or free). Analytical methods commonly used include the single trigonometric series of Lévy, the double trigonometric series of Navier, the power series expansions, etc. In this paper the deflection surface was approximated with the sum of a particular solution to the governing differential equation (GDE) and two single series. The terms of the single series were the product of an unknown function of an independent variable and a trigonometric function of the other independent variable, whereby the trigonometric functions were chosen to vanish at the corner points. On the one hand the terms of the series were required to satisfy the homogeneous GDE, leading to two uncoupled differential equations, one for each unknown function, and so the approximate solution satisfied exactly the GDE. On the other hand the boundary conditions were satisfied only at selected collocation points along the boundary, the number of collocation points in each direction corresponding to the number of terms of the associated series. Results for several plates supported at all corner points with arbitrary edge support conditions were presented and showed good agreement with the exact results, the accuracy increasing the more terms of series were considered.

Article
Engineering
Civil Engineering

Nopanom Kaewhanam

,

Bin Wang

,

Chaicharn Chotetanorm

,

Apichit Kampala

,

Sitthiphat Eua-Apiwatch

,

Sivarit Sultornsanee

,

Krit Chaimoon

Abstract: Finite element models of ultra-high-performance concrete (UHPC) deep beams are usually judged by peak load, yet a correct capacity can come with a wrong mechanism. Our earlier shell-element study of these beams reported 104–107% of the measured capacity for normal- and high-strength concrete (NSC, HSC) and 63% for UHPC, ratios that would be 0.32–0.54 if its predictions are applied loads, with flexural failure where the tests failed in shear and a code-derived UHPC tensile strength 38% below the measured value. A 2 × 2 design—layered shell versus solid elements, each with a code-derived and a measured tensile strength—separates the two causes in four beams. The shell model failed in flexure and over-predicted capacity 1.25–2.86 times; its element effect (with elastic transverse shear), −0.61 to −2.06, far exceeded the tension effect, −0.05 to +0.09. The measured tensile strength raised the solid UHPC predictions by 11–25%, yet left them at 0.72–0.73, consistent with missing fibre bridging but not separable from the mesh dependence of the solid model. The solid model came within 5–21% of the capacity of the beams without fibres, yet failed by diagonal cracking where the tests failed in diagonal compression. Peak-load agreement does not validate a deep-beam model.

Review
Engineering
Architecture, Building and Construction

Abdallah Almajdoub

Abstract: Saudi Arabia is trying to deliver housing and giga-project accommodation at a pace that conventional wet construction struggles to sustain. The Ministry of Municipalities and Housing has set a target of 40% of new houses built with modern methods of construction (MMC) by 2030, and its Modern Building Initiative supports six MMC technologies and has financed more than 22 factories. Yet the peer-reviewed evidence on how offsite, modular and prefabricated construction performs in Saudi conditions is thin and scattered. This review brings together Saudi and Gulf empirical studies (surveys, case studies, economic modelling and risk analyses) with the main international reviews on modular integrated construction (MiC), prefabrication and design for manufacture and assembly (DfMA). A scoping search in OpenAlex on 6 November 2026 returned 38 records for Saudi-specific offsite terms, of which only eight dealt with building offsite construction on title screening; targeted searches and citation tracking raised the final base to 37 peer-reviewed sources, supported by 13 official and industry sources for policy facts. The evidence shows that speed, labour dependence and quality drive interest, while cost, late design freeze, supply-chain gaps, transport limits, regulatory routes, skills and a strong preference for traditional methods hold adoption back. The Saudi studies repeat the international pattern, but with two local features: very high reliance on expatriate site labour and a policy push that is ahead of design practice. The paper proposes the Saudi Offsite Readiness Model (SORM), with seven dimensions, five maturity levels, 28 measurable indicators, a weakest-link scoring rule and a stage-by-stage checklist written for architects. A research agenda closes the paper.

Article
Engineering
Transportation Science and Technology

Petr Nachtigall

,

Michaela Krbálková

,

Jaromír Široký

,

Ivana Matoušová

,

Petr Příhoda

Abstract: Electrifying urban bus routes requires an integrated assessment of energy demand, vehicle scheduling and charging infrastructure availability. This study evaluates the operational and energy feasibility of deploying battery-electric buses on Route 6 of the urban public transport network in Pardubice, Czechia, using a combination of overnight depot charging and opportunity charging at a terminal. The methodology integrates operational data and route timetables with an energy balance model and a time-based simulation of battery state of charge (SoC). The winter scenario assumes an energy consumption of 2.7 kWh·km⁻¹, a nominal battery capacity of 346 kWh and a single terminal charging point rated at 350 kW. In all simulated vehicle duties, the minimum SoC remained above the operational threshold of 30% established by the authors. Standard weekday schedule E, with 20-minute charging sessions, recorded both a minimum and final SoC of 69.6% over a distance of 162.5 km. Weekend schedule G reached a minimum SoC of 58.0% and a final SoC of 70.5% over 221.7 km. The limiting weekday scenario C, with 15-minute charging sessions outside peak periods, reached a minimum SoC of 34.9% and ended at 49.0% over 211.2 km. The findings indicate that the proposed concept is energetically feasible under the specified conditions, but do not establish its operational robustness. Critical factors include the availability of scheduled charging windows, competing charging demands from multiple vehicles and the reliability of the single charging point. The model does not account for charging conflicts, equipment failures, battery degradation or interactions with other routes. Further assessment therefore requires probabilistic analysis and validation using year-round operational data.

Review
Engineering
Civil Engineering

Zofia Szweda

,

Magdalena Kocha

,

Jan Będkowski

,

Oskar Wręczycki

,

Damian Kwaśny

,

Wojciech Tomala

,

Artur Skórkowski

,

Michał Dronszczyk

,

Kacper Pawlucy

,

Marie Horňáková

Abstract: The durability and safety of cathodic protection (CP) in reinforced and prestressed concrete depend on interactions among electrode materials, electrochemical conditions, and structural response. This critical review examines how anode composition, microstructure, conductive layers, concrete resistivity, and current distribution affect protection performance and material degradation. Laboratory studies, numerical simulations, and field evidence are compared for titanium/mixed-metal-oxide anodes, zinc-based galvanic systems, graphite and carbon-modified cementitious materials, polymeric coatings, and contact mortars. Particular attention is paid to interfacial processes, distinguishing initial conductivity and current delivery from electrochemical stability, anode consumption, and demonstrated service life. Accelerated aging and field exposure are treated as complementary, but non-equivalent, evidence of durability. For prestressing steel, the effects of cathodic polarization, strength, stress state, and exposure on hydrogen-assisted damage are examined; meeting protection criteria alone does not establish hydrogen safety. Instant-off potentials, depolarization measurements, and electrochemical impedance spectroscopy are assessed alongside material and structural diagnostics, including their limitations. A three-dimensional P–T–B framework distinguishes local protection performance (P), technological durability (T), and material and structural safety (B). Standardized characterization and long-term validation remain necessary before laboratory findings can inform prestressed-concrete applications under realistic operating and environmental exposure conditions.

Article
Engineering
Mechanical Engineering

Lijie Liu

,

Yicheng Lu

,

Yilin Guo

,

Zefeng Yu

,

Yu Zhang

,

Shan Tang

,

Xu Guo

Abstract: Learning reusable local operators can accelerate thermoelastic topology optimization, yet accurate stiffness prediction alone does not ensure accurate thermal-force transfer between fields. A hybrid Problem-Independent Machine Learning (PIML) framework combines reference-anchored thermal shape-function learning with mechanical residual-enriched static condensation. A fixed-trace error analysis exposes the mechanism: stiffness errors are quadratic about interior equilibrium, whereas thermal-load projection can retain first-order errors. This distinction motivates a field-specific strategy that learns the compact thermal response and corrects the larger mechanical response from current-material equilibrium. Shared Ritz factors supply stiffness, coupling and local state/adjoint products without mechanical training or explicitly forming the full mechanical basis. Across eight three-dimensional optimization benchmarks exceeding one million fine elements each, thermal designs have compliance gaps below 0.3% relative to full finite element method (FEM) reference designs; coupled designs have mixed-objective gaps below 0.027% relative to exact linear-boundary substructure references. Complete coupled optimizations are 4.75–5.05× faster than exact Q1 substructuring in total online time. In separate warmed benchmarks covering states, sensitivities and update proposals, the coupled hybrid gives a 186× speedup over matched Full FEM and reduces peak working-set memory by 94.4%. On a 32 GB laptop, a coupled plate with 30.752 million analysis cells is optimized in 60.54 min using 14.17 GiB peak resident memory. The framework extends reusable local learning from separate-field stiffness approximation to accurate, memory-efficient coupled design.

Article
Engineering
Chemical Engineering

Benjamin Ray

,

Ali Reza Mirgolbabaei

,

Hessam Mirgolbabaei

Abstract: Accurate reconstruction of hydrocarbon species beyond those used to construct a low-dimensional manifold is important for data-driven combustion modeling. This Short Communication investigates principal-component-analysis/artificial-neural-network (PCA–ANN) reconstruction of four light hydrocarbons in a two-dimensional ethanol pool-fire simulation using the 2016 San Diego Mechanism. Ten principal components, capturing 99.939% of the variance, were derived from temperature and a modified Millán-Merino 17-species reference set. Acetylene (C₂H₂) and ethylene (C₂H₄) were included in manifold construction, whereas methane (CH₄) and ethane (C₂H₆) were excluded. All four species exhibited strong reconstruction agreement, with squared Pearson correlation coefficients ranging from 0.9746 to 0.9959. Notably, the excluded species CH₄ and C₂H₆ achieved R² values of 0.9959 and 0.99174, respectively. Instantaneous spatial analysis at t = 1 s revealed species-dependent error localization, with more than 92% of the squared reconstruction errors for C₂H₂ and C₂H₄ concentrated within approximately 1–1.5% of the computational domain. These findings demonstrate that reduced thermochemical coordinates can preserve sufficient information to reconstruct hydrocarbons excluded from PCA construction, while emphasizing the importance of spatially resolved accuracy assessment.

Article
Engineering
Electrical and Electronic Engineering

Rose Pagano

,

Cole Milanovic

,

Erik Cunha

,

Klajdi Moglica

,

Daniel Gangapersaud

,

Rupinder Kaur

,

Arghavan Asad

Abstract: Low-cost camera-based doorbells can provide visitor information through embedded image capture and remote inference, but recognition quality and user-visible delay must be evaluated together. This paper presents an ESP32-CAM prototype that captures an image when a visitor presses a button and transfers it to a cloud backend. RetinaFace detects and aligns faces, and ArcFace produces 512-dimensional embeddings through the DeepFace framework. Stored profiles in Firebase Firestore support known/unknown classification, while a mobile application presents an initial image notification followed by a recognition update. Evaluation uses 50 classification events and 14 timing pairs. The results give 91.7% precision, 100% recall, 95.7% F1-score, and 94.0% accuracy. Three of 17 unknown events were incorrectly classified as known, corresponding to a 17.6% unknown-event false-positive rate. Mean initial-notification and recognition-endpoint times were 4.70 and 8.05 s, respectively. The listed hardware components total CAD 29.98, excluding deployment and recurring service costs. These findings demonstrate feasibility of the integrated sensing and notification pipeline while identifying false acceptance, incomplete experimental documentation, and cloud-dependent delay as limitations requiring further validation before residential deployment.

Article
Engineering
Energy and Fuel Technology

Raffaello Possidente

,

Andrea Frattolillo

,

Roberto Baccoli

,

Costantino Carlo Mastino

,

Manuela Piga

Abstract: Renewable Energy Communities (RECs) represent a promising pathway to acceler-ate the integration of distributed renewable energy sources while enhancing local en-ergy self-consumption and citizen participation in the energy transition. This study investigates the energy and economic performance of a REC configuration developed for the municipality of Pattada, a rural community in Sardinia, Italy, with particular attention to the role of a municipally owned Battery Energy Storage System (BESS). The analysis is based on the assessment of photovoltaic generation, electricity demand profiles, and mechanisms governing Virtually Shared Energy (VSE) within the community. Two scenarios were evaluated and compared: a reference configuration without storage and an alternative configuration including a 750 kWh BESS connected to municipal photovoltaic systems. The results indicate that the REC reaches its most effective balance with approxi-mately 700 residential users in the absence of storage and 500 users when the BESS is introduced. While the storage system significantly increases municipal self-consumption, reaching 229.35 MWh/year and 45% of local photovoltaic production, it reduces the amount of energy available for virtual sharing among community members. Economic indicators reveal superior profitability for the storage-free configuration, which achieves a payback period of approximately 5.5 years, an internal rate of return of 12.7%, and positive net present values under all investigated scenarios. The findings provide practical insights into the optimal design of RECs in rural and island contexts, highlighting the trade-offs between individual self-consumption enhancement and community-wide energy sharing.

Article
Engineering
Electrical and Electronic Engineering

Victor Chukwuma Iheanacho

,

Sergejs Tjukovs

,

Darja Cirjulina

,

Ruslans Babajans

,

Sandis Migla

,

Dmitrijs Pikulins

Abstract: Chaotic electronic oscillators generate broadband, noise-like signals for applications such as chaos-based communications. Their practical use requires chaos that persists despite component tolerances and changing conditions. Conventional numerical scans may overlook narrow periodic windows and thus overestimate the robustness of chaos. This paper presents DynamicsKit.jl, an open-source Julia framework integrating numerical continuation, bifurcation analysis, Lyapunov exponents, operating maps, and basin analysis for discrete maps and, through Poincaré return maps, continuous-time systems. Operational robustness is assessed by combining Lyapunov exponent tests, searches for stable periodic orbits, and basin analysis at progressively finer resolutions. The methodology is demonstrated on four representative electronic circuits. For the Vilnius oscillator and a memristive diode-bridge circuit, refined searches reveal periodic windows covering about 13% and 2% of bands that passed an initial low-resolution assessment. Component-tolerance simulations predict periodic behaviour in 29–43% of oscillator realisations at the published set point, 0.3–1.5% at alternative set points with the gain trimmed, and about 3% of memristive-circuit realisations with a lossless inductor. The framework also identifies an unphysical always-on fixed point in a buck-converter map and detects no stable periodic window in the examined boost-converter band. The results assess operational robustness systematically under realistic parameter variations, without claiming mathematical proof.

Concept Paper
Engineering
Telecommunications

Van Le

,

Leila Walden

,

Tan Le

Abstract: While Low Earth Orbit (LEO) satellite constellations face increasing vulnerabilities in contested radio frequency environments, tropospheric scatter (troposcatter) communications provide a resilient, space-independent Beyond-Line-of-Sight (BLOS) alternative for tactical networks. However, escalating climate volatility increasingly induces non-stationary atmospheric ducting layers—such as marine evaporation ducts and thermal inversions—that severely alter the vertical modified refractivity profile, causing catastrophic multipath trapping, deep fading, and link outages. Classical numerical wave solvers suffer from prohibitive computational complexity that prevents real-time deployment on tactical edge modems, whereas pure data-driven deep learning models lack physical inductive biases and fail during out-of-distribution weather anomalies. To address these fundamental limitations, we propose a hybrid Quantum Physics-Informed Neural Network (QPINN) integrated within a hierarchical Space-Ground Environmental Digital Twin (SG-EDT) architecture for real-time troposcatter link adaptation. The QPINN encodes classical atmospheric telemetry into a variational quantum circuit with entangling gates, leveraging Hilbert-space representation learning to evaluate concurrent multi-variable cross-correlations. Crucially, the model embeds exact 2D narrow-angle Parabolic Wave Equation constraints alongside a Huberized thermodynamic gradient penalty bounded by physical atmospheric trapping boundaries directly into the autograd optimization loop. Evaluated on tactical edge hardware, our framework eliminates loss penalty explosions, achieves high-fidelity refractivity profile reconstruction, and executes low-latency forward inference, enabling preemptive Adaptive Transmit Power Control (ATPC) and spatial nulling before multipath link degradation occurs.

Article
Engineering
Transportation Science and Technology

Osman Bağcı

,

Satılmış Ürgün

,

Sinan Fidan

,

Mustafa Özgür Bora

Abstract: Integrity of the Ground-Based Augmentation System (GBAS) relies on protection levels based on broadcast error models and on ground monitors comparing several reference receivers. Both were examined at an Istanbul reference station with real, independently labelled GPS code jumps. On 60,269 smoothed test epochs of a 23.8 km station pair, the ICAO Annex 10 fault-free vertical protection level bounded the error at every epoch when the error model was calibrated to the data tails; with standard models it was exceeded at 20 epochs for weighted least squares, but the error never exceeded the 10 m alert limit. With two to four simulated reference receivers, B-value monitoring detected almost all 20 m single-receiver jumps, so user-side exclusion and robust estimation mattered mainly for single-receiver stations and unmonitored faults. Adding Galileo reduced the median VDOP at Istanbul Airport from 1.48 to 1.10 and raised correct exclusion of two simultaneous faults injected into real smoothed code from 59% to 95%. Rare Galileo E1 code deviations of about one chip occurred at the reference station during signal acquisition; exclusion kept their vertical effect below 4 m, versus about 100 m without it. All findings held on 18 independent October days with frozen error models.

Article
Engineering
Electrical and Electronic Engineering

Berthold Klaus Paul Horn

Abstract: When it comes to indoor localization, is spatial diversity better than frequency diversity? Ranging with respect toWi-Fi access points is useful for indoor localization, but has been thought to be limited to 1–2 m accuracy when using the IEEE 802.11mc protocol. It has been shown that line-of-sight measurements of the distance between a phone and aWi-Fi access point can be more accurate when measurements taken at different frequencies are combined. Here, we show that this frequency-diversity advantage also applies to the determination of location—even when the signals are subject to multipath, diffraction and refractive retardation. The newer IEEE 802.11az protocol, not yet widely implemented, provides sub-meter accuracy more directly, in part because of spatial diversity. We compare 1these two approaches. In previous work, the Bayesian grid update method has been shown to be effective in determining locations from range measurements. This method uses an observation model—the conditional probability distribution of the measured distance versus the actual distance. Good results can be obtained with a simple generic observation model, but the accuracy can be increased by adjusting the observation model. The best model parameters can be found using the maximum-likelihood method. We demonstrate that in a typical cluttered indoor environment 1/2 m accuracy in localization can be achieved using either (i) IEEE 802.11mc with frequency diversity or (ii) IEEE 802.11az with spatial diversity. Even higher accuracy is possible if spatial diversity and frequency diversity are combined—albeit at the cost of slower update rates.

Article
Engineering
Electrical and Electronic Engineering

Mohsen Karimi

Abstract: This paper presents a criterion-based framework for the design and evaluation of a parallel-plate electrostatic balance mass comparator (PEBM). The framework establishes sufficient conditions for strict monotonicity of the transfer characteristic, a necessary condition for unique code generation on the weighting network, and conditions guaranteeing monotonicity preservation, absence of missing codes, and a maximum inter-code deviation of one bit. The weighting network is defined over 2N − 1 discrete steps for N weights, and a comparator dead-band condition is incorporated into the design criteria. A systematic design procedure is formulated that links the geometric and electrical parameters of the balance to measurable code-level properties. The theoretical criteria are validated through numerical simulations of the transfer characteristic and code sequence. An experimental protocol based on cross-validation against a reference balance is defined for the quantitative characterisation of the prototype. The contribution of this work is a set of explicit design criteria, bounds, and verification procedures that make the code behaviour of an electrostatic mass comparator predictable and testable.

Article
Engineering
Mechanical Engineering

Peng Yang

,

Bingchu Li

,

Kuanhao Gu

,

Bei Lu

Abstract: Friction monitoring is essential for the precision control and fault diagnosis of electromechanical actuators (EMAs). This paper presents a friction estimator that reconstructs friction under various loads and velocities solely from motor current signals. The estimator consists of a preprocessing stage and an extrapolation training stage using a physics-informed neural network (PINN). In the preprocessing stage, basic Stribeck parameters are estimated from no-load constant-speed measurements. In the extrapolation training stage, a load-augmented Stribeck law is embedded as a soft constraint within the PINN, and friction is distinguished from reflected load torque by its velocity-structured baseline. Because the load dependence is encoded in the physical law, the estimator extrapolates to loads absent from training, reconstructing the friction map from limited samples; a theoretical analysis derives the conditions for well-posed extrapolation. In dynamic simulations, the preprocessing stage estimates the base Stribeck parameters with a mean relative error of 0.87%. On graded load-extrapolation experiments, the constrained PINN keeps the mean relative error close to 1% at loads far beyond the maximum training load, about 90% lower than data-driven methods, and predicts friction in untrained dynamic processes with a mean relative error below 4.8%. Few quasi-static points thus suffice to reconstruct the full velocity–load friction map without force or torque sensors, and periodic re-estimation can track friction over the service life.

Article
Engineering
Architecture, Building and Construction

Mady Ahmed Mohamed

,

Rabab S. Qataya

,

Hussien AlShanwany

,

Shimaa Sabour

Abstract: Standardized school prototypes are replicated across Egypt regardless of local wind, yet the effect of courtyard orientation on classroom ventilation and summer comfort remains poorly quantified. This study assessed a five-story prototype in hot-arid Cairo using validated non-isothermal computational fluid dynamics (CFD) for four courtyard orientations (0°, 15°, 30° and 45° relative to the prevailing August wind), combined with adaptive and heat-balance comfort indices. The realizable k–ε model reproduced measured classroom temperatures with a root-mean-square error of 0.31 K, and discretization uncertainty was below 1.5%. The wind-aligned layout gave the highest mean classroom air speed (0.44 m/s) and the lowest air temperature (31.1 °C); rotations of 15–45° reduced air speed by 19–29% and raised air temperature by 1.5–4.0 K, well above the model uncertainty. No orientation met the 80% acceptability limit of the ASHRAE 55 adaptive model (30.4 °C). The aligned classroom would comply only with ceiling fans providing at least 0.6 m/s, whereas rotated layouts would also need substantial heat-gain reductions; Coupled Model Intercomparison Project Phase 6 projections indicate that this margin is exhausted at about 2 K of regional warming. Courtyard alignment is necessary but insufficient and must be combined with elevated air movement and heat-gain control.

Article
Engineering
Control and Systems Engineering

Praskovya L. Pavlova

,

Yuri N. Bezborodov

,

Petr M. Kondrashov

,

Ilya I. Karnaukhov

,

Alexander S. Lunev

,

Elena N. Fedorova

,

Elena V. Tsygankova

Abstract: Thermal interaction between oil and gas wells and permafrost rocks leads to their thawing which can cause infrastructure deformation, greenhouse gas emissions, and landscape degradation. This paper presents a simplified engineering method for estimating the thaw radius around a cylindrical well with a constant wall temperature. Based on the Stefan condition and a quasi-steady-state temperature distribution in the thawed zone, an analytical formula (Equation 9) is derived. This formula explicitly relates the thaw radius to the well radius, thermal conductivity of the thawed soil, ice content, and latent heat of fusion, wall temperature, and time. The method accounts for the heterogeneity of the geological profile by identifying intervals with average thermophysical properties. Calculations for typical permafrost conditions (loam, ice content of 0.3, initial temperature - 2 °C, wall temperature - 5 °C) show that the thaw radius reaches 4.3 m after three years and exceeds 14 m after ten years at a wall temperature of 6 °C. Ice content slows down thawing, while high thermal conductivity accelerates it. The proposed formula has been verified by comparison with a finite-difference numerical model and the Kutasov–Eppelbaum method; the discrepancy does not exceed 15 %, which is acceptable for conservative engineering estimates. The method is suitable for rapid calculations to account for depth-dependent variations in permafrost properties. The results contribute to sustainable infrastructure design in permafrost regions by enabling quantitative assessment of safe well spacing, selection of operational regimes, and well thermal protection methods.

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