Search Results (11,483)

Steel portal frames are widely used in industrial buildings due to their high strength-to-weight ratio and rapid erection capability. However, many existing structures exhibit insufficient load-carrying capacity under current design requirements. This study investigates the use of external post-tensioning (PT) cables and rigid wedge anchorages to enhance the overall performance of steel portal frames. Two stages of numerical analysis were performed: (i) two-dimensional parametric studies to identify the most efficient configuration and (ii) three-dimensional verification under combined gravity, wind, and seismic loading conditions. Results show that the proposed PT system significantly increases the load-carrying capacity of both beams and columns, reduces bending demands, and improves global stability without major geometric modification. The strengthening method is safe, reversible, and offers a practical alternative to conventional welded or plated retrofit techniques. Full article

MCSGP (Multicolumn Countercurrent Solvent Gradient Purification) with AutoPeak control is increasingly used for production of synthetic peptides and oligonucleotides at scale, requiring guidance on how to perform regulatory-compliant Process Validation. This work, for the first time, presents a Process Characterization and Process Performance Qualification approach to support regulatory filings of therapeutics produced using MCSGP, based on the relevant Process Validation guidelines. The approach was demonstrated for the purification of synthetic Bivalirudin. During Process Characterization, MCSGP process parameter criticality was investigated, and the gradient slope was classified as a critical process parameter to be controlled within tighter limits. As a further outcome of Process Characterization, a supervision strategy was developed and verified in four Process Performance Qualification MCSGP runs. The strategy was backed by AutoPeak, a UV-based Process Analytical Technology. The Process Validation/Process Performance Qualification (PPQ) runs not only confirmed the selected control and supervision strategy but also the advantages of MCSGP/AutoPeak as a continuous manufacturing technology, including the fully automatic operation and the reduction in in-process control sampling and Process Mass Intensity (PMI). In the presented case, the PMI was reduced from around 5200 to 1400 kg/kg, the number of in-process controls (IPCs) was reduced from 81 IPCs (60 cm i.D. column batch) per kg to 3.2 IPCs per kg (2 × 30 cm i.D. column MCSGP), while yield (gross-to-gross) increased from 57% to 62%, comparing MCSGP/AutoPeak to a process with extensive side-cut recycling. Full article

Concrete-filled steel tube (CFST) columns are composite structural elements preferred in various engineering structures due to their superior properties compared to those of traditional structural elements. However, fire resistance analyses are complex due to CFST columns consisting of two components with different thermal and mechanical properties. Significant challenges arise because current design codes and guidelines do not provide clear guidance for determining the time-dependent fire performance of these composite elements. This study aimed to address the existing design gap by investigating the fire behavior of circular long CFST columns under axial compressive load and developing robust, accurate, and reliable design models to predict their fire performance. To this end, an up-to-date database consisting of 62 data-points obtained from experimental studies involving variable material properties, dimensions, and load ratios was created. Analytical design models were meticulously developed using two advanced soft computing techniques: artificial neural networks (ANNs) and genetic expression programming (GEP). The model inputs were determined as six main independent parameters: steel tube diameter (D), wall thickness (t_s), concrete compressive strength (f_c), steel yield strength (f_sy), the slenderness ratio (L/D), and the load ratio (μ). The performance of the developed models was comprehensively compared with experimental data and existing design models. While existing design formulas could not predict time-based fire performance, the developed models demonstrated superior prediction accuracy. The GEP-based model performed well with an R-squared value of 0.937, while the ANN-based model achieved the highest prediction performance with an R-squared value of 0.972. Furthermore, the ANN model demonstrated its excellent prediction capability with a minimal mean absolute percentage error (MAPE = 4.41). Based on the nRMSE classification, the GEP-based model proved to be in the good performance category with an nRMSE value of 0.15, whereas the ANN model was in the excellent performance category with a value of 0.10. Fitness function (f) and performance index (PI) values were used to assess the models’ accuracy; the ANN (f = 1.13; PI = 0.05) and GEP (f = 1.19; PI = 0.08) models demonstrated statistical reliability by offering values appropriate for the expected targets (f ≈ 1; PI ≈ 0). Consequently, it was concluded that these statistically convincing and reliable design models can be used to consistently and accurately predict the time-dependent fire resistance of axially loaded, circular, long CFST columns when adequate design formulas are not available in existing codes. Full article

This study conducts a numerical investigation of the geometry of the oscillating water column (OWC) wave energy converter under realistic irregular wave conditions found off the coast of Rio Grande, southern Brazil. Two OWC models were compared: the conventional design and the L-shaped configuration (L-OWC). The OWC structure consists of a hydropneumatic chamber and an air duct, where a turbine is coupled to an electric generator. Additionally, in the L-shaped chamber configuration, a water intake duct is considered. The constructal design method was employed for the geometric evaluation of the devices. For the L-OWC, the influence of the height-to-length ratio of the water intake duct on the obtained hydropneumatic power available was analyzed. In parallel, for the conventional OWC, the free-board submergence was investigated. Subsequently, the optimal geometry for each OWC model was selected to study the height-to-length ratio of the hydropneumatic chamber. Numerical simulations were performed using ANSYS Fluent software. Thus, the performance of the converters was improved by approximately 35.76 times for the L-OWC and 3.78 times for the conventional OWC. However, it is noteworthy that the optimal configuration of the conventional OWC achieved a performance 2.62 times higher than the optimal L-OWC geometry. Full article

We present the concept of an ultracold neutron (UCN) source with a superfluid He-4 (SF ${}^4$He) converter located in the thermal column of the WWR-K research reactor at the Institute of Nuclear Physics (INP) in Almaty, Kazakhstan. The conceptual design is based on the proposal of accumulating UCNs in the source and effectively transporting them to experimental setups. We propose to improve the UCN density in the source by separating the heat and UCN transport from the production volume and decreasing the temperature of the SF ${}^4$He converter to below about 1 K. To obtain operation temperatures below 1 K, we plan to use a He-3 pumping cryogenic system and minimize the thermal load on the UCN accumulation trap walls. Additional gain in the total number of accumulated UCNs can be achieved through the use of a material with a high critical velocity for the walls of the accumulation trap. The implementation of such a design critically depends on the availability of materials with specific UCN and cryogenic properties. This paper describes the conceptual design of the source, discusses its implementation methods and material requirements, and plans for material testing studies. Full article

This study investigates the removal of copper and zinc at environmentally relevant concentrations from aqueous solutions using barista coffee waste in both standalone and blended forms (with rice husk biochar). A fixed-bed horizontal column adsorption study was conducted to determine the effects of contact time, adsorbent type, and initial metal concentration on the removal efficiency. As far as we are aware, this study is the first to focus on eliminating low concentrations in accordance with World Health Organization (WHO) guideline levels, employing a horizontal fixed-bed column setup. Adsorption equilibrium was achieved around six hours after initiation and resulted in a high percentage of metal removal (up to 96.71%). Ground coffee waste performed better for lower initial metal concentrations (2.5 ppm copper and 10 ppm zinc), although a mixture of coffee waste and biochar performed better at concentrations greater than 5 ppm for copper and 25 ppm for zinc. Experimental results were applied to the Thomas model to determine the efficiency of the adsorbents. Results indicated it was linear with a good correlation coefficient (R² = 0.94). The experimental data also fitted the pseudo-first-order reaction kinetic with a higher correlation coefficient (R² = 0.93) than the second-order reaction kinetics. The experimental and calculated values were very similar for the first-order reaction kinetic. The metal adsorption was affected by both external mass transfer and intra-particle diffusion mechanisms. This study developed an engineered solution to remove heavy metals from wastewater using widely available ground coffee waste as an effective adsorbent. Full article

The diversity of clinical presentations and outcomes of COVID-19 suggests the influence of host-intrinsic factors that modulate the infectious process. Therefore, a study was conducted with professionals from a hospital in the state of Sergipe, in the Northeast region of Brazil, aiming to identify in this population the effect of rs12329760 and rs2070788, SNPs of the TMPRSS2 enzyme that facilitates the infectious process. Recruitment of the 363 participants followed a non-probabilistic method using a QR code that led to the Informed Consent Form (ICF) and a clinical–epidemiological questionnaire based on self-reported information on the number of positive tests, the presence/absence of symptoms, and severity. Buccal epithelial cells were collected, DNA was extracted using a silica column, and SNP amplification was performed by qPCR. The data were processed using PSPP software, using chi-squared tests for associations in three statistical genetic models (additive, dominant, and recessive). The results showed that, in this population, rs12329760 did not influence any of the outcomes, while rs2070788 was significant in both the additive and recessive models. The action of the G allele is evident in the most severe cases, and it is associated with increased TMPRSS2 expression and potentially increased viral entry efficiency. Full article

In this study, a novel hybrid adsorbent polydopamine-based nano-zirconium phosphate coated resin (DPZrP) was successfully synthesized, where zirconium phosphate (ZrP) was surface-anchored onto a polystyrene ion-exchange resin (D001) via polydopamine (PDA) mediation. Characterization results indicated that PDA, acting as an interfacial bridge, not only achieved the stable loading of ZrP but also exerted a spatial confinement effect on ZrP through its polymeric cross-linked structure, thereby effectively suppressing the agglomeration of nanoparticles. Compared with pristine D001 and pure ZrP, the hybrid material DPZrP exhibited superior adsorption performance for Cs⁺. The adsorption capacity of DPZrP for Cs⁺ reached a theoretical maximum of 921.99 mg/g at 333 K. Adsorption kinetic studies indicated that adsorption equilibrium was reached within 120 min, and the reaction rate constant was 1.55 times that of DZrP. The pH effect experiment showed that DPZrP maintained Cs⁺ removal rates of 73.4% and 58.1% under strongly acidic (pH = 2) and strongly alkaline (pH = 12) conditions, respectively. When the molar ratio of Ca²⁺ to Cs⁺ was as high as 64, the Cs⁺ removal rate of DPZrP was 19.3% and 30.4% higher than those of DZrP and D001, respectively. Dynamic column experiments revealed that after treating 2000 bed volumes of simulated wastewater ([Cs⁺]₀ = 2.5 mg/L), the Cs⁺ concentration in the effluent remained below 0.5 μg/L, with breakthrough occurring at 3000 BV. After five consecutive adsorption–desorption cycles, the Cs⁺ removal rate of DPZrP remained at 88.4%. These studies confirmed the dispersion effect of PDA on ZrP, and the synthesized DPZrP possessed both rapid capture ability and high adsorption capacity for Cs⁺. Thus, it provides an efficient adsorbent for the safe purification of nuclear waste liquids. Full article

It is well known that elevated phosphate concentrations in water bodies trigger the eutrophication process, posing adverse environmental, health, and economic consequences that necessitate effective removal solutions. Phosphate removal has therefore been widely studied using various methods, including chemical precipitation, membrane filtration, and crystallisation. However, most of these methods are often expensive or inefficient for low phosphate concentrations. Therefore, in this study, an eco-friendly, sustainable and biodegradable adsorbent was manufactured by extracting calcium ions from an industrial by-product, ground granulated blast furnace slag (GGBS) and magnesium ions from magnesium dross (MgD), then immobilising them on sodium alginate to form Ca-Mg-SA beads. The new adsorbent was applied to remove phosphate from water under different flow patterns (batch and continuous flow), initial pH levels, contact times, agitation speeds and adsorbent doses. Additionally, the degradation time of the new adsorbent, recycling potential, its morphology, formation of functional groups and chemical composition were investigated. The results obtained from batch experiments demonstrated that the new adsorbent achieved 90.2% phosphate removal efficiency from a 10 mg/L initial concentration, with a maximum adsorption capacity of 1.75 mg P/g at an initial pH of 7, a contact time of 120 min, an agitation speed of 200 rpm and an adsorbent dose of 1.25 g/50 mL. The column experiments demonstrated a 0.82 mg P/g removal capacity under the same optimal conditions as the batch experiments. The findings also showed that the adsorption process fitted well to the Freundlich and Langmuir isotherm models and followed a pseudo-second-order kinetic model. Characterisation of Ca-Mg-SA beads using EDX, SEM and FTIR confirmed successful ion immobilisation and phosphate adsorption. Furthermore, the beads fully biodegraded in soil within 75 days and demonstrated potential recycling as a fertiliser. Full article

Ocean waves constitute a vast renewable resource, yet most linear generator-based wave energy converters (WECs) rely on single-degree-of-freedom (SDOF) linear oscillators that exhibit narrow resonance bandwidths and utilise sliding components prone to wear. To address these limitations, this paper presents a nonlinear three-degree-of-freedom (3DOF) magnetic spring power-take-off (PTO) system for broadband wave energy harvesting. The device comprises three axially levitated NdFeB permanent magnets, each coupled to an independent copper coil, forming a compact, friction-free generator column. A coupled electromechanical state-space model was developed and experimentally validated on a laboratory-scale test rig. The 3DOF PTO exhibited three distinct resonance modes at approximately 35, 48, and 69 rad s⁻¹, enabling multi-mode energy capture across a broad frequency range. Under identical excitation (6.5 N amplitude and 3.13 Hz excitation force), the 3DOF configuration achieved a 114.5% increase in RMS voltage compared with the SDOF design and a 44.10% improvement over the 2DOF benchmark, confirming the effectiveness of the coupled resonance mechanism. The levitated magnetic architecture eliminates mechanical contact and lubrication, reducing wear and maintenance while improving long-term reliability in marine environments. A preliminary life-cycle assessment estimated a cradle-to-gate carbon intensity of 40–80 g CO₂-eq kWh⁻¹, significantly lower than that of conventional hydraulic PTOs, owing to reduced steel use and recyclable magnet assemblies. The proposed 3DOF magnetic spring PTO thus offers a sustainable, low-maintenance, and high-efficiency solution for next-generation ocean-energy converters. Full article

Lightning strikes are a major cause of wind turbine (WT) damage, with approximately 80% of cloud-to-ground lightning strikes exhibiting a multi-stroke characteristic. Therefore, studying the transient overvoltages induced by multiple lightning strokes is essential for the effective lightning protection of offshore WTs. Firstly, a multiple-stroke lightning current model representative of Guangdong Province, China, is established based on data from the lightning location system and rocket-triggered lightning experiments. Simulations are then employed to analyze the transient overvoltage of a Guangdong offshore wind farm under multiple lightning strikes. Simulation results indicate that when a WT is subjected to a two-stroke lightning flash, with current amplitudes corresponding to a cumulative probability density of approximately 1%, the surge arrester A1 must be configured with four parallel columns to ensure the insulation safety of the equipment without sustaining damage. Additionally, adequate electrical clearance must be maintained between the power cable and the tower wall, or alternatively, a high-strength insulating material may be applied over the cable armor to prevent flashover. Moreover, it is observed that the front time of the impulse current flowing through the surge arrester is approximately 2 μs, significantly shorter than the front time specified in IEC 60099-4 for the repetitive charge transfer capability test of ZnO varistors. Hence, it is essential to consider local lightning intensity and distribution characteristics when studying the transient overvoltages in offshore wind farms, optimizing surge arrester configurations, and assessing the impulse withstand performance of ZnO varistors, in order to ensure the safe and stable operation of offshore WTs. Full article

The urgent need to address climate change has driven the exploration of sustainable energy solutions, with wave energy and green hydrogen emerging as prominent alternatives to traditional fossil fuels. This study examines the potential synergy between wave energy and hydrogen production, with a focus on the economic viability of integrating these technologies. Through a detailed analysis of the levelised cost of electricity (LCOE) and the levelised cost of hydrogen (LCOH), this paper examines how coastal regions in Portugal and across Western Europe can harness wave energy to produce green hydrogen, a crucial component in the global energy transition. The techno-economic assessment accounts for capital and operational costs, energy efficiency, and lifetime performance to determine how design and location affect economic feasibility. Preliminary analysis indicates that regions with significant wave power potential present opportunities for competitive LCOE values, with some coastal areas achieving LCOE figures as low as 0.10 €/kWh. Additionally, the LCOH analysis reveals that among various storage methods, compressed gas hydrogen at 350 bar stands out as the most cost-effective option. This research highlights the transformative potential of wave energy-driven hydrogen production as a crucial solution for decarbonising the maritime sector. Future technological advancements and cost efficiencies are poised to overcome current economic barriers and accelerate the transition to a sustainable, low-carbon energy landscape. Full article

This paper presents a knowledge-based and interpretative model for the conservation of the House of Arianna, located in the Archaeological Park of Pompeii, developed within the CHANGES project, Spoke 6—History, Conservation and Restoration of Cultural Heritage. The research focused on two critical components of the site: the free-standing peristyle columns and the mosaic and frescoed surfaces preserved in situ. This workflow yielded a high-resolution digital model, analytical condition maps, and diagnostic datasets that directly inform conservation decisions. The results show that the columns exhibit internal discontinuities and weaknesses at their joints, a condition linked to heterogeneous construction techniques which increases the risk of drum slippage under wind and seismic loading. The mosaics display a marked loss of tesserae in exposed sectors over recent years, driven by moisture ingress, biological growth and mechanical stress. These findings support the adoption of low-impact, reversible measures, embedded within a prevention-first strategy based on planned conservation. The study formalizes a replicable methodology that aligns diagnostics, monitoring and conservation planning. By linking ‘skin’ and ‘structure’ within a unified interpretative matrix, the approach enhances both structural safety and material legibility. The workflow proposed here offers transferable guidance for the sustainable preservation and inclusive interpretation of exposed archaeological ensembles in the Vesuvian context and beyond. Full article

Pesticides are chemical substances widely used to control, prevent, or eliminate pests in agriculture, gardening, and other sectors. However, their use poses risks to human health, and recent regulatory efforts have focused on minimizing exposure and monitoring residue levels. In this study, the separation of seven pesticides was investigated using supercritical fluid chromatography coupled to diode-array detection (SFC-DAD). The influence of six different stationary phases and various organic modifiers, as well as additional parameters such as temperature, pressure, and the presence of additives, was systematically evaluated to optimize the chromatographic conditions. The best separation performance was achieved using a LiChrospher^® 100 DIOL column with methanol as the organic modifier under a gradient program. Analyses were carried out at a flow rate of 3 mL/min, a column temperature of 35 °C, and a system back pressure of 150 bar, resulting in a total analysis time of approximately 4 min. The optimized method allowed for a faster separation of the selected agricultural pesticides by SFC-DAD compared to conventional chromatographic techniques. Full article

This paper describes an ultra-high-speed monolithic global shutter CMOS image sensor capable of continuous motion capture at 326,000 fps with a resolution of 640 × 480 pixels. The performance is enabled by a novel combination of pixel technology and circuit techniques. The highly sensitive BSI pixel with a 52 μm pitch employs a fully depleted substrate to facilitate rapid photocarrier transport. In-pixel voltage mode storage enables pipelined readout, while in-pixel analog CDS provides low noise with minimal impact on readout speed. The sensor achieves an equivalent row time of 6.4 ns through separate top and bottom readout together with multiple parallel ADCs per column. Independent row drivers on both the left and right sides ensure the global shutter accuracy needed for the minimum exposure time of 59 ns. The dynamic range is enhanced by on-chip reduction in FPN and by PTC-based data compression. The sensor delivers a throughput of 100 Gpix/sec, transferred off chip via 128 CML channels operating at 6.6 Gbps each. The device is fabricated using a 130 nm monolithic CIS process with BSI postprocessing and is in series production. Full article