Search Results (230)

Cryogenic high-manganese austenitic steel is used in liquefied natural gas (LNG) storage tanks and has a lower thermal expansion coefficient than other cryogenic steels. Because it is joined to stainless steel in the loading system, dissimilar welding is required. Three-dimensional thermal elastic–plastic finite element analysis and sectioning measurements were performed on 15-mm-thick high-manganese steel/STS304 dissimilar butt welds, and the residual stress was analysed separately in the longitudinal and transverse components. The analysis predicted a steep gradient at the weld metal–STS304 interface 8.5 mm from the weld centre, where the transverse stress falls to about −230 MPa. The longitudinal peak differed from the homogeneous joint by only 77 MPa (−11.7%), within the analysis–measurement deviation (RMSE 103–127 MPa). Of the four properties substituted individually, the expansion coefficient gave the highest reproduction ratio (57.9% on average) and alone reproduced the interfacial compression; substituting all four reproduced the effect almost completely (102.4%). The transverse stress range increased linearly with the expansion mismatch (R² = 0.978), whereas the longitudinal range did not (R² = 0.002). Assessment by peak residual stress alone therefore misses the interfacial gradient and the compressive zone specific to dissimilar joints. Full article

Palm oil mill effluent (POME), the primary liquid residue from crude palm oil (CPO) extraction, has shifted from industrial wastewater to a valuable feedstock for renewable energy and resource recovery. This review synthesizes recent developments in sustainable POME management in Malaysia through a narrative review of peer-reviewed literature (Scopus, Web of Science, Google Scholar; 2013 onwards) and institutional reports, across four dimensions: anaerobic digestion technologies, environmental performance, techno-economic viability, and policy drivers. Characterized by a high organic load (COD 15,000–100,000 mg L⁻¹; BOD 10,250–43,750 mg L⁻¹), POME yields roughly 28–34 m³ of biogas per m³ of effluent with a 54–65% methane content, while its digestate offers nutrient recovery potential to replace synthetic fertilizers. Covered lagoons and continuous stirred-tank reactors (CSTRs) show the highest deployment potential, whereas upflow anaerobic sludge blanket (UASB) systems and anaerobic membrane bioreactors (AnMBRs) remain technically and economically constrained. Capital intensity, infrastructure gaps, and operational demands limit wider adoption. At the same time, digital process control and regulatory drivers such as the Malaysian Sustainable Palm Oil (MSPO) certification and the European Union Deforestation Regulation (EUDR) are critical enablers. Re-envisioning POME management as an integrated resource-recovery platform can lower greenhouse gas emissions, close nutrient loops, and accelerate Malaysia’s circular bioeconomy. Full article

Rainwater Collection System (RWCS) is a sustainable water management technology suitable for the collection and storage of rainwater from roofs and surfaces for reuse to promote sustainable water resource management. This study investigated four RWCSs to be used in public schools across the Philippines. These RWCSs are: (1) Aboveground Steel Tank (A-S), (2) Aboveground Polyethylene Tank (A-P), (3) Underground Reinforced Concrete Tank (U-C), and (4) Underground Polyethylene Tank (U-P). Life Cycle Assessment was utilized to consider the environmental performance of four RWCSs with the use of SimaPro (10.5.0.1). A cradle-to-site system boundary was adopted encompassing two life cycle stages: manufacturing and installation. The results showed that the Underground Concrete Tank system (U-C) consistently exhibited the lowest environmental impact across all impact categories, and the Aboveground Steel Tank system (A-S) demonstrated the highest impacts, primarily due to the significant use of reinforcing and structural steel for its base and foundation. In particular, the global warming potential (GWP) and human carcinogenic toxicity (HCT) of U-C are lower than those of the other RWCSs from 47.3% to 59.4% and 44.1% to 93.3%, respectively. In addition, the construction cost of U-C is 20.4% to 35.1% lower than that of the other RWCSs. Future research is recommended to expand the system boundary to include use and end-of-life stages, which may influence the comparative outcomes. Full article

The building heat demand and the energy system capacity are usually designed independently in solar heating systems for rural houses in cold regions. This leads to oversized system capacity and a lack of collaborative design between the building side and the energy system side. To address these issues, a building–PVT collaborative passive–active design framework was proposed for a typical rural house in Lanzhou, Gansu Province, China. First, a dynamic building thermal model was developed in EnergyPlus. Four typical building configurations, including a baseline house, an insulated house, a sunspace house, and a sunspace house with an intelligent thermal curtain, were established. The hourly heating demand over 8760 h was obtained for each configuration. Then, the hourly building heating demand was used as the unified boundary condition to develop a dynamic PVT heating system model in MATLAB. The responses of the PVT collector area, thermal storage tank volume, and auxiliary heater capacity to building heat demand were analyzed. A CSR was further proposed to establish a quantitative relationship between building heating load reduction and PVT system capacity reduction. Finally, a collaborative multi-objective optimization was carried out using the NSGA-II with the objectives of maximizing the SF and minimizing the LCC. The TOPSIS was adopted to determine the optimal compromise solution. The results show that the integrated passive design combining a sunspace with an intelligent thermal curtain reduces the annual heating energy consumption by 44.0% compared with the baseline house. The reduction in building heat demand simultaneously decreases the required PVT system capacity. The PVT collector area, thermal storage tank volume, and auxiliary heater capacity decrease by 44.14%, 27.55%, and 25.78%, respectively. This indicates that passive building energy-saving measures significantly change the design boundary of the energy system. The proposed CSR effectively quantifies the capacity substitution effect of building-side energy saving on the PVT heating system, and the integrated passive design achieves the highest overall CSR. The multi-objective optimization generates a uniformly distributed Pareto front. The optimal compromise solution achieves an SF of 86.41% with an LCC of 8.34 × 10⁴ CNY. The recommended configuration includes a 50 mm insulation layer, a 40 m² sunspace, a 12.62 m² PVT collector area, and a 1.23 m³ thermal storage tank. Compared with the initial design, the optimized configuration significantly improves solar energy utilization while maintaining a low LCC and further reducing the required auxiliary heater capacity. This study establishes a collaborative analysis framework between building heat demand and PVT system capacity. A quantitative mapping method between building heating load and system capacity is proposed. The framework enables integrated optimization of building thermal design and energy system capacity configuration. The proposed method provides a new theoretical approach and practical guidance for the design of solar heating systems for rural houses in cold regions. Full article

This study investigates how non-ideal electromechanical actuation influences the emergence and modulation of complex dynamics in dissipative nonlinear systems. A hybrid four-dimensional model is formulated by coupling a continuous stirred tank reactor (CSTR) with Haldane substrate-inhibition kinetics to a non-ideal electromechanical power source, explicitly accounting for the bidirectional interaction between the mechanical driver and the biochemical process. Numerical simulations and Lyapunov spectrum analysis are employed to characterize the resulting nonlinear dynamics and synchronization properties. The results show that the mechanical subsystem can evolve toward a high-energy chaotic regime with non-ideal rotational velocity pulsations, while the reactor subsystem retains a negative conditional Lyapunov exponent over a broad parameter range despite the presence of global chaos. This dynamical configuration characterizes generalized synchronization, in which the dissipative reactor response becomes functionally constrained by the chaotic mechanical attractor. In addition, the parametric analysis demonstrates that variations in coupling strength can either transmit complex oscillatory behavior or suppress chaos, depending on the operating regime. These findings indicate that aperiodic oscillations in process variables may originate from deterministic electromechanical coupling rather than intrinsic chemical instabilities and highlight the dual role of non-ideal actuation as both a source of nonlinear complexity and a potential mechanism for stabilization and control in hybrid engineering systems. Full article

Variations and unstable characteristics of two-phase flow in oil and gas pipelines readily induce severe equipment vibration and internal liquid sloshing, which seriously endanger the safety of pipeline systems. Existing investigations on conventional T-junctions have been restricted to single working conditions, without systematic optimization of structural parameters across multiple flow regimes or full evaluation of integrated separation and slug suppression performance. To address this research gap, this work proposed an optimized four-branch T-junction. The geometric configuration of the T-junction was optimized, and a test prototype was fabricated for gas–liquid two-phase flow experiments. Combined with experimental measurements and computational fluid dynamics (CFD) simulations, the overall performance of the optimized T-junction was comprehensively analyzed under diverse flow patterns and operating conditions. The test results indicated that the gas separation efficiency exceeded 90% under stratified flow, whereas slug flow brought strongly time-dependent separation performance. The gas separation efficiency was maintained above 40% for all test cases. The optimized structure reduced liquid slug velocity and length and significantly suppressed liquid level fluctuations in the downstream separation tank. The numerical predictions agreed well with experimental data, which validated the reliability of the present numerical framework. This study provides technical references for the design of inline pipe separators that realize both gas–liquid separation and slug mitigation. Full article

The proposed wave rotor enhanced nuclear propulsion (WREN) system is a potential technology candidate for timely and efficient manned missions to Mars. Using Hydrogen (H₂), conventional nuclear thermal propulsion (NTP) can attain an ${\mathrm{I}}_{sp}$ of 800–1000 s as it reaches the thermal limits of its solid core reactor material. A four-port wave rotor turbomachine coupled to a closed Brayton cycle can go beyond this limitation, further heating the H₂ to attain an ${\mathrm{I}}_{sp}$ of 1400–1500 s. Despite this improvement, liquid H₂ currently poses significant storage problems that limit transit performance. This work explores the use of denser propellants that use the full launch mass of a rocket compared to liquid H₂. This includes ammonia (NH₃), water (H₂O), and methane (CH₄). Using NERVA-class NTP technology, the ${\mathrm{I}}_{sp}$ of these alternatives is comparable to chemical rockets. The WREN fluid and subsystem cycle was modeled using an object-oriented hardware sizing program equipped with NASA CEA thermochemistry and coupled to an optimization framework. Given a specific set of constraints, a 25-klb_f (111.2 kN) class WREN engine produced $I_{sp}$ values of 663.6 s for NH₃, 469.6 s for H₂O, and 360.1 s for CH₄. NH₃ and H₂O achieved density-impulse values comparable to vacuum-rated hydrolox engines, making them competitive with in-space chemical rockets on a volumetric basis. NH₃ provided the strongest overall balance of $I_{sp}$, storage density, and $\mathrm{\Delta }V$ favorability compared with H₂ NTP, whereas H₂O produced a small radiator that enabled a higher thrust-to-weight regime. At a representative $\mathrm{\Delta }V$ of 12 km/s, the propellant savings of NH₃ WREN reduced the combined propellant-tank and radiator launch elements from 27 launches for conventional NH₃ NTP to 13 launches, of which only nine were propellant-tank launches. Full article

Liquid-hydrogen fuel-cell propulsion is a promising option for reducing the climate impact of short-range aviation, but its aircraft-level feasibility depends on the concurrent integration of cryogenic storage, megawatt-class propulsion systems, and thermal management. This paper presents an integrated conceptual design and technology-sensitivity assessment of a 101-passenger liquid-hydrogen fuel-cell aircraft, targeting a 1000 nmi design range and a 2040 entry into service, framed within the European Union FAME project. A JPAD-based aircraft sizing framework is coupled with a surrogate model for cryogenic tank sizing to investigate how selected hydrogen-subsystem characteristics propagate, through mission-fuel and tank-sizing convergence loops, to configuration-level performance and compliance with top-level aircraft requirements. The storage-system trade study identifies 2.0 bar as the most favourable sampled tank venting pressure; relative to the other investigated pressure levels, this solution reduces MTOM and design-mission block fuel by up to 8.1% and 9.2%, respectively. The propulsion-architecture study selects a four-engine layout as the best compromise between one-engine-inoperative performance, spanwise structural relief, nacelle drag, and mission fuel consumption, yielding a 2.6–2.7% lower MTOM and a 3.5–3.7% lower design-mission block fuel than the two- and six-engine alternatives. A technology-sensitivity matrix spanning 51–55% fuel-cell efficiency and 60–100% cooling-line speed recovery reveals a non-linear increase in installed power, aircraft mass, and hydrogen consumption as either parameter deteriorates. For the fixed-geometry FAME baseline, the onset of multiple TLAR violations occurs as speed recovery falls through approximately the 70–80% region, depending on fuel-cell efficiency. Within the assumptions of the present model, maintaining fuel-cell efficiency at or above approximately 53% and cooling-line speed recovery above this transition region therefore represents an approximate feasibility condition. Full article

To address the need for low-power, real-time underwater acoustic signal processing and autonomous target detection on deep-sea unmanned mobile platforms, such as profiling acoustic buoys and underwater gliders, this study developed an embedded Linux-based signal processing system for buoy platforms. Conventional digital signal processing hardware platforms are often constrained by large size, high power consumption, and limited data communication capability. The proposed system adopts a compact, low-power architecture and a multithreaded processing framework based on the AM6254 heterogeneous multicore processor. It acquires four-channel vector-hydrophone signals together with attitude data from an inertial navigation module and performs band-pass filtering, fast Fourier transform (FFT), direction-of-arrival (DOA) estimation, and constant false alarm rate (CFAR) detection for autonomous target detection. The measured typical power consumption was approximately 2.3 W. Anechoic-tank and sea-trial results showed the lowest tested spectral level at which autonomous detection was achieved was 54 dB at 1 kHz, corresponding to an average in-band level of 46 dB. Under sea state 3, the system maintained continuous bearing tracking after target acquisition for a surface target traveling at 7 kn, up to a range of approximately 7 km, and provided unambiguous bearing estimation. These results demonstrate the target-detection capability and practical applicability of the system under representative operating conditions and indicate its potential for marine environmental monitoring and unmanned-platform observation and detection. Full article

The global energy transition and rapid electrification are driving increased demand for copper. However, conventional pyrometallurgical and hydrometallurgical extraction routes are increasingly challenged by declining ore grades and stricter environmental regulations. Bioleaching involves the microbial catalysis of sulfide mineral dissolution and provides a sustainable method for copper recovery from low-grade ores, tailings and secondary resources. This review provides a critical and integrated analysis of copper sulfide bioleaching, covering microbial diversity, molecular mechanisms, mineralogical controls, operational parameters, and industrial applications. This review also examines the functional roles of prominent acidophiles, including the functional roles of prominent acidophiles, including Acidithiobacillus spp., Leptospirillum spp. and thermophilic archaea, in the oxidation of iron and sulfur, mitigation of passivation, and metal solubilization. The molecular underpinnings of these processes are explored by investigating iron and sulfur oxidation gene networks (the rus operon and sox cluster), copper resistance systems (CopA, CusCBA) and biofilm formation pathways. The mineralogical controls on the behavior of chalcopyrite (refractory/passivating), chalcocite (highly reactive) and bornite (intermediate) are critically assessed. The synergistic effects of key operational parameters (temperature, pH, redox potential, aeration and particle size) on leaching kinetics and microbial community dynamics are investigated. The scalability, efficiency and environmental footprint of industrial applications such as heap, dump, stirred-tank and in situ bioleaching are discussed. Despite more than four decades of commercial development, several challenges remain, such as slow chalcopyrite dissolution, passivation, metal toxicity, and scale-up limitations. Emerging solutions such as synthetic microbial consortia, multi-omics technologies, artificial intelligence-assisted optimization, and digital twins are identified as transformative approaches for next-generation biomining. In this review, microbiology, mineralogy, electrochemistry, and process engineering are integrated to demonstrate that biotechnological leaching is among the most promising technologies for the sustainable production of copper and to identify future directions for its industrial application. Full article

Renewable-powered agricultural water systems are often assessed as solar-pumping devices, but their sustainability depends on a service chain linking crop-water demand, hydraulic duty point, power electronics, storage, water quality, governance, operation and end-of-life management. This structured integrative review synthesizes peer-reviewed and practice-oriented evidence on photovoltaic pumping, hybrid renewable irrigation, grid-interactive pumps, micro-hydro assistance and renewable-powered brackish-water reverse osmosis (PV-RO). Evidence was screened across four source families and coded by service function, energy architecture, hydraulic duty and dominant sustainability pathway; recurring combinations were consolidated using explicit separation and merge rules. It develops an archetype-based screening framework for ex ante appraisal of irrigation, desalination and circularity risks. Seven technology-service archetypes are identified: direct PV pumping, PV-to-tank pumping, PV with electrical buffering, grid-interactive PV pumping, PV–wind hybrid irrigation, micro-hydro-assisted irrigation and PV-RO water making. The framework links each archetype to its operating envelope, evidence maturity, enabling subsystems, sustainability pathways, minimum indicators and ordinal triggers for deeper due diligence. Hydraulic storage is usually the lowest-regret reliability buffer for open-field irrigation, whereas batteries are justified mainly when pressure stability, fertigation timing or night-time operation has high agronomic value. PV-RO is a distinct water-making archetype and is environmentally defensible only where feed-water characterization, energy recovery, pretreatment, product-water agronomy, membrane management and permitted concentrate disposal are embedded in design. Two synthetic applications demonstrate archetype selection and due-diligence escalation. Responsible deployment requires service-oriented screening that integrates hydraulic design, groundwater governance, procurement quality assurance, circularity obligations and social inclusion before field implementation. Full article

Refined oil depots are critical nodes in energy supply chains. Tank truck queuing increases costs and idling carbon emissions while reducing customer satisfaction. This research proposes a modified finite capacity Markovian queuing system (M/M/c/N) with random service interruptions and establishes a multi-objective model covering expected cost, carbon emissions and customer satisfaction. We derive core metrics and formulate corresponding unit time objective functions. The Bayesian optimization-based NSGA-II (BO-NSGA-II) hybrid algorithm is adopted to solve the proposed model. Comparisons against four algorithms are conducted using four multi-objective evaluation metrics: hypervolume (HV), Inverted Generational Distance (IGD), generational distance (GD) and spacing, which confirm that BO-NSGA-II achieves a balanced overall performance. Its HV reaches 0.657, while IGD (0.0066), GD (0.0009) and spacing (0.0069) remain low, demonstrating broad Pareto front coverage, high convergence accuracy and uniform solution distribution. Trade-off analysis indicates that the algorithm entails a marginal expected cost increase of merely 1.15% compared with the minimum expected cost solution obtained by MOEA/D. Meanwhile, carbon emissions drop to 11.25 kgCO₂/h and customer satisfaction rises to 0.9769, achieving coordinated economic, environmental and service benefits. Sensitivity analysis further identifies the optimal loading bay configuration range of 2 to 4. Insufficient allocation leads to congestion, while excessive allocation causes equipment idling and higher emissions. Blind expansion also raises the expected cost. This study provides methodological references for the collaborative optimization of oil depot resource allocation, low-carbon scheduling and service performance. Full article

This paper presents a decentralized adaptive generalized-minimum-variance (GMV) control framework for large-scale stochastic nonlinear systems composed of interconnected multi-input multi-output (MIMO) Hammerstein subsystems with unknown time-varying parameters. Each subsystem consists of a coupled multivariable static nonlinearity represented on a known invertible basis, followed by a matrix-polynomial dynamic block affected by colored noise and delayed input–output interconnections. The proposed scheme estimates only identifiable composite Hammerstein parameters through a decentralized recursive extended least-squares algorithm with forgetting, thereby avoiding the non-unique separation of nonlinear and linear gains. A constructive matrix Diophantine identity is established to derive an optimal multi-step predictor, leading to a GMV control law expressed as a multivariable polynomial equation in the current input. Sufficient conditions for real solvability, mean-square boundedness, and near-optimal adaptive tracking are provided using Hadamard–Lévy global-diffeomorphism, minimum-phase, small-gain, persistent-excitation, strict-positive-realness, and convex-projection arguments, and the implemented controller—inexact Newton solver with fallback and persistent dither—is itself covered by the analysis. The analysis further shows that delayed interconnections become measurable and can be exactly compensated, while robustness to basis under-modeling is explicitly quantified. Simulation results on an interconnected two-subsystem MIMO Hammerstein process with coupled cubic nonlinearities, colored noise, delayed interactions, and time-varying parameters—run in the forgetting-factor regime required by the theory, with measured persistent excitation and complete solver diagnostics—demonstrate operational-noise-floor tracking and a $2.3$-fold mean-RMSE reduction relative to the strongest linear-MIMO surrogate, while a channel-wise SISO Hammerstein design fails structurally and a feedback-linearization controller with exactly known nonlinearity offers no advantage. The study further demonstrates scalability on a chain of four subsystems with size-independent per-subsystem computational cost, validates a physically motivated interconnected coupled-tank network with progressive-valve nonlinearities, and confirms agreement between the observed stability limits and the predicted small-gain boundary. Full article

Rooftop rainwater harvesting (RWH) offers a practical adaptation option for Mediterranean cities where water scarcity is amplified by seasonal rainfall and climate variability. This study reports early findings from a simplified monthly water balance screening model for a typical residential building, driven by ERA5-Land monthly precipitation for Antalya and İzmir (Türkiye). Scenarios cover roof areas of 250–3000 m² and practical tank capacities of 2–100 m³ under a fixed non-potable demand of 0.20 m³/day. The model tracks monthly storage dynamics and supply demand in order to compute demand coverage and monthly reliability (i.e., fraction of months in which full demand is met). Reliability-based storage thresholds (≥0.80) are derived for four evaluation windows (1996–2010, 2011–2025, 1996–2025, 1950–2025) to explore climate sensitivity. In parallel, a guideline-style sizing which is consistent with the Turkish rainwater harvesting guideline is implemented using a three-day storage rule based on the wettest month potential. To enable a like-for-like comparison, the collection losses are harmonized by setting loss to 0.10 in the simulation and efficiency to 0.90 in the guideline method. The results show stable thresholds for Antalya but stronger period sensitivity in İzmir. They also quantify cases where guideline sizing does not achieve the target reliability under dry season constraints. This approach supports the rapid, climate-aware pre-design of small- to medium-scale urban RWH systems. Full article

Liquid storage tanks are widely used in sectors such as water treatment, oil and gas, food processing, and chemical manufacturing. Knowing the exact amount of liquid in a tank is essential for ensuring safety, preventing spills, and optimizing process control; therefore, the liquid level in a tank must be maintained at a precise reference point. This is where liquid level control for tanks becomes crucial and constitutes a fundamental problem in the industrial sector due to nonlinearities, multivariable coupling, and stochastic disturbances. Given the drawbacks of available control methods, such as classical Model Predictive Control (MPC), which are highly dependent on model accuracy and struggle to reject complex stochastic noise, predicting random disturbances represents a major technological challenge. A new approach is proposed to specifically address the problem and challenge of the four-tank system, where water levels in two lower tanks must be controlled by two pumps, often with varying delays and significant parameter disturbances. To establish a relationship between expected performance and MPC parameters, this approach uses a novel hybrid nonlinear MPC, Extended State Observer, and Physics-Informed Neural State Estimation (NMPC-ESO-PINSE) architecture. A Physics-Informed Neural State Estimation (PINSE) layer, chosen for its learning capacity, is designed to filter sensor noise by applying Bernoulli’s physical laws, while an Extended State Observer (ESO) is integrated to capture and compensate for unmodeled uncertainties in the process. Finally, a proposed hybrid (NMPC-ESO-PINSE) strategy leverages these clean, physically consistent state estimations to solve a non-convex optimization problem via Sequential Quadratic Programming (SQP), computing optimal pump voltages. Extensive numerical simulations demonstrate the superior resilience of this decoupled framework against parametric drifts and continuous noise sequences, yielding a $+27.36\%$ reduction in global Root Mean Square Error (RMSE) compared to standard NMPC, accelerating the closed-loop settling time to $15.2 \mathrm{s}$, and restricting transient overshoot to just $0.18\%$. Full article