Search Results (765)

Sediment transport in urban streams is a critical environmental issue, with significant implications for water quality, ecosystem health, and infrastructure management. Accurately estimating suspended sediment concentration (SSC) is essential for effective long-term environmental management. This study investigates the relationships between streamflow, turbidity, and SSC in Dry Creek, South Australia, to understand sediment transport dynamics in urbanised catchments. We collected grab samples from the field and analysed them in the laboratory. We employed statistical modelling to develop a sediment rating curve (SRC) that provides insights into the sediment transport dynamics in the urban stream. The grab sample measurements showed variations in SSC between 3.2 and 431.8 mg/L, with a median value of 77.3 mg/L. The analysis revealed a strong linear relationship between streamflow and SSC, while turbidity exhibited a two-regime linear relationship, in which the low-turbidity regime demonstrated a stronger linear relationship compared to the high-turbidity regime. This is attributed to the urbanised nature of the catchment, which contributes to a first-flush effect in turbidity. This contributes to sediment hysteresis, resulting in non-proportional turbidity and SSC responses to streamflow changes. The findings demonstrate the effectiveness of a streamflow-based SRC for accurately predicting sediment discharge, explaining 97% of the variability in sediment discharge. The sediment discharge predicted using the SRC indicated a sediment load of 341.8 tonnes per year along the creek. The developed sediment rating curve provides a valuable tool for long-term sediment management in Dry Creek, enabling the assessment of downstream environmental risks. By addressing data limitations, this study contributes to a deeper understanding of sediment transport dynamics in urbanized environments, offering insights for informed decision-making and effective sediment management strategies. Full article

The impact of dynamic processes on equilibrium properties is a fundamental issue in condensed matter physics. This study investigates the intrinsic ferromagnetism generated by memory effects in the low-dimensional continuous symmetry Landau–Ginzburg model, demonstrating how memory effects can suppress fluctuations and stabilize long-range magnetic order. Our results provide compelling evidence that tuning dynamical processes can significantly alter the behavior of systems in equilibrium. We quantitatively evaluate how the emergence of the ferromagnetic phase depends on memory effects and confirm the presence of ferromagnetism through simulations of hysteresis loops, spontaneous magnetization, and magnetic domain structures in the 1D continuous symmetry Landau–Ginzburg model. This research offers both theoretical and numerical insights for identifying new phases of matter by dynamically modifying equilibrium properties. Full article

Energy loss in shielding soft magnetic materials at low frequencies (1–100 Hz) can cause fluctuations in the material’s magnetic field, and the resulting magnetic noise can interfere with the measurement accuracy and basic precision physics of biomagnetic signals. This places higher demands on the credibility and accuracy of loss separation predictions. The current statistical loss theory (STL) method tends to ignore the high impact of the excitation dependence of quasi-static loss in the low-frequency band on the prediction accuracy. STL simultaneously fits and predicts multiple unknown quantities, causing its results to occasionally fall into the value boundary, and the credibility is low in the low-frequency band and with less data. This paper proposes a progressive loss decomposition (PLD) method. Through multi-step progressive predictions, the hysteresis loss simulation coefficients are first determined. The experimental data of the test ring verifies the credibility of PLD’s prediction of the two hysteresis coefficients, improving the inapplicability of the STL method. In addition, we use the proposed method to obtain the prediction results of the low-frequency characteristics of the loss of a variety of typical soft magnetic materials, providing a reference for analyzing the loss characteristics of materials. Full article

Diverse domain patterns significantly influence the nonlinear electromechanical behaviors of ferroelectric nanomaterials, with polarization switching under strong electric fields being inherently a frequency-dependent phenomenon. Nevertheless, research in this area remains limited. In this study, we present a phase-field investigation of frequency-dependent electromechanical dynamics of a polycrystalline BaTiO₃ nanofilm with a core-shell structure, subjected to applied frequencies ranging from 1 to 80 kHz. Our findings elucidate the microstructural mechanisms underlying the electromechanical behaviors observed in these materials. The effect of the grain size and the strains effect are also taken into account. Hysteresis and butterfly loops exhibit a marked change in shape as the frequency changes. We discuss the underlying domain-switching dynamics as a basis for evaluating such frequency-dependent properties. In addition, we examine the scaling behaviors of the dynamic hysteresis and the influence of grain boundaries on the domain structure. We can also observe from hysteresis loops that the remnant polarization and coercive field significantly diminish when grain sizes decrease from 60 to 5 nm. A smaller grain size of the nanofilm yields a larger percentage of the dielectric grain boundary, which “dilutes” the overall ferroelectricity of the film. A vortex domain structure is more likely to form at low frequency and a small grain size. Full article

The high-performance vector control technology of permanent magnet synchronous machines (PMSMs) relies on high-precision rotor position. The Hall-effect sensor has the advantages of low cost, simple installation, and strong anti-interference ability. However, it can only provide six discrete rotor angles in an electrical cycle, which makes high-precision vector control of PMSMs difficult. Hence, to obtain the necessary rotor position of PMSMs, a rotor position fitting method combining the Hall signal and machine flux information is proposed. Firstly, the rotor position signal output by the Hall-effect sensors is used to calibrate and update the stator flux obtained under pure integration. Then, based on the corrected stator flux and its relationship with current and angle, the rotor position and speed are obtained. Experimental verification shows that the rotor position observer combining Hall signal and flux information can reduce the initial value bias and integral drift caused by traditional average speed method hysteresis and pure integration method calculation of flux and can quickly and accurately track and estimate the rotor position, achieving high-performance vector control of PMSMs. Full article

The impact of the interface phenomena on the properties of nanostructured materials is the focus of modern physics. We studied the magnetic properties of the nanostructured In–Ag alloy confined within a porous glass. The alloy composition was close to the eutectic point in the indium-rich range of the phase diagram. Temperature dependences of DC magnetization evidenced two superconducting transitions at 4.05 and 3.38 K. The magnetization isotherms demonstrated the superposition of two hysteresis loops with low and high critical fields below the second transition, a single hysteresis between the transitions and ferromagnetism with weak remanence in the normal state of the alloy. The shape of the loop seen below the second transition, which closes at a low magnetic field, corresponded to the intermediate state of the type-I superconductor. It was ascribed to strongly linked indium segregates. The loop observed below the first transition is referred to as type-II superconductivity. The secondary and tertiary magnetization branches measured at decreasing and increasing fields were shifted relative to each other, revealing the proximity of superconducting and ferromagnetic phases at the nanometer scale. This phenomenon was observed for the first time in the alloy, whose components were not magnetic in bulk. The sign of the shift shows the dominant role of the stray fields of ferromagnetic regions. Ferromagnetism was suggested to emerge at the interface between the In and AgIn₂ segregates. Full article

U-shaped seismic dampers, passive metallic devices that dissipate energy by cyclic plastic deformation, are designed to mitigate the effects of seismic loads on structures. This study focuses on the development of an advanced computational model of a U-shaped damper, chosen for its unique design of variable thickness and width, which contributes to its superior performance. The simulation uses nonlinear finite element analysis and a bilinear hardening model calibrated to the actual stress–strain curve of the low-carbon steel. To ensure accuracy, a rigorous mesh convergence analysis is performed to quantify numerical prediction errors and establish a model suitable for predicting local deformation phenomena, including strain and stress fields, throughout the displacement-based loading protocol. Mesh sensitivity analysis, performed by examining the equivalent stress and cumulative plastic strain, derives the damper hysteresis curve and confirms the convergence criteria of the mesh within the experimentally observed plastic response range of the material. The resulting computational model is a novel contribution that provides reliable predictions of local inhomogeneous deformation and energy dissipation, essential for optimizing damper design and performance through more sophisticated damage-fatigue models that guarantee the lifetime of a damper. Full article

Andean purple corn (Zea mays L.) is an ancient native Peruvian crop that is currently used in Peruvian gastronomy. Cushuro is a cyanobacteria from the Andean lakes of Peru. They have considerable amounts of bioactive compounds that can improve the physicochemical properties of foods. The objective of this research was to characterize the rheological and functional properties of food hydrogels developed with purple corn extracts, red prickly pear fruit pulp, and cushuro polysaccharide (CP). Acid-soluble polysaccharides obtained from the Nostoc sphaericum variety from Ancash, Peru, as well as Peruvian purple corn extracts, were used. Food hydrogels at concentrations ranging from 0.5% to 3.5% (w/v) were elaborated by dispersing the polysaccharides in a 4:1 extract/pulp (v/v) ratio. Likewise, control samples with Tara (Caesalpinia spinosa) gum (TG) were made. The effect of hydrocolloid concentration (0.5; 1.5; 2.5; 3.5%) on the rheological properties was evaluated using a unifactorial design. CP and TG hydrogels exhibited a shear-thinning nature, a concentration-dependent yield point (0.02–29.91 Pa; 2.01–508.39 Pa), and high antioxidant activity and phenolic content. Adding CP revealed slow structural regeneration, while TG showed thixotropy and a symmetric hysteresis loop. CP gels showed a fluid-like structure with viscoelastic properties (G″ > G′) even in the highest concentration evaluated (3.5%), contrary to TG gel that had a more solid (gel-like) structure (G′ > G″) at a low concentration (1.5%). These results showed a suitable rheological profile and desirable properties of the food hydrogels development for the functional food industry and processing. Full article

This paper addresses critical gaps in the digital implementations of fractional-order memelement emulators, particularly given the challenges associated with the development of solid-state devices using nanomaterials. Despite the potentials of these devices for industrial applications, the digital implementation of fractional-order models has received limited attention. This research contributes to bridging this knowledge gap by presenting the FPGA realization of the memelements based on a universal voltage-controlled circuit topology. The digital emulators successfully exhibit the pinched hysteresis behaviors of memristors, memcapacitors, and meminductors, showing the retention of historical states of their constitutive electronic variables. Additionally, we analyze the impact of the fractional-order parameters and excitation frequencies on the behaviors of the memelements. The design methodology involves using Xilinx System Generator for DSP blocks to lay out the architectures of the emulators, with synthesis and gate-level implementation performed on the Xilinx Artix-7 AC701 Evaluation kit, where resource utilization on hardware accounts for about $1\%$ of available hardware resources. Further hardware analysis shows successful timing validation and low power consumption across all designs, with an average on-chip power of 0.23 Watts and average worst negative slack of 0.6 ns against a 5 ns constraint. We validate these results with Matlab 2020b simulations, which aligns with the hardware models. Full article

Recently, there has been a huge increase in the different ways to manufacture polymer-based sensors. Methods like additive manufacturing, microfluidic preparation, and brush painting are just a few examples of new approaches designed to improve sensor features like self-healing, higher sensitivity, reduced drift over time, and lower hysteresis. That being said, we believe there is still a lot of potential to boost the performance of current sensors by applying modeling, classification, and machine learning techniques. With this approach, final sensor users may benefit from inexpensive computational methods instead of dealing with the already mentioned manufacturing routes. In this study, a total of 96 specimens of two commercial brands of Force Sensing Resistors (FSRs) were characterized under the error metrics of drift and hysteresis; the characterization was performed at multiple input voltages in a tailored test bench. It was found that the output voltage at null force (V_{o_null}) of a given specimen is inversely correlated with its drift error, and, consequently, it is possible to predict the sensor’s performance by performing inexpensive electrical measurements on the sensor before deploying it to the final application. Hysteresis error was also studied in regard to V_{o_null} readings; nonetheless, a relationship between V_{o_null} and hysteresis was not found. However, a classification rule base on k-means clustering method was implemented; the clustering allowed us to distinguish in advance between sensors with high and low hysteresis by relying solely on V_{o_null} readings; the method was successfully implemented on Peratech SP200 sensors, but it could be applied to Interlink FSR402 sensors. With the aim of providing a comprehensive insight of the experimental data, the theoretical foundations of FSRs are also presented and correlated with the introduced modeling/classification techniques. Full article

To understand the asymmetric flow of a slender body with low-aspect ratio fins, a wind tunnel experiment was carried out, and the asymmetric flow was observed when the pair of fins had a symmetric deflection angle of 30° at a small angle of attack and zero sideslip angle at transonic speeds. The unsteady characteristics of flow around the moving fins, especially for the evolution of the asymmetric flow, was carefully numerically investigated via the RANS method. To verify the numerical method, the experimental steady wind tunnel data of the NACA 0012 airfoil with sinusoidal pitching motion were adopted. A hysteresis loop exists as a function of the deflection angle during the upstroke and downstroke motions. The side force is periodic due to the asymmetric flow peaks at the downstroke and their peak value appeared at around δz = 25°, which was independent of the deflection frequency. As the deflection frequency increased, the asymmetric flow formed at a higher deflection angle during the upstroke motion, but decayed at a lower deflection angle during the downstroke motion, resulting in a more significant unsteady hysteresis effect. Full article

Piezoelectric actuators (PEAs) are extensively used for scanning and positioning in scanning probe microscopy (SPM) due to their high precision, simple construction, and fast response. However, there are significant challenges for instrument designers due to their nonlinear properties. Nonlinear properties make precise and accurate control difficult in cases where position feedback sensors cannot be employed. However, the performance of PEA-driven scanners can be significantly improved without position feedback sensors if an accurate mathematical model with low computational costs is applied to reduce hysteresis and other nonlinear effects. Various methods have been proposed for modeling PEAs, but most of them have limitations in terms of their accuracy and computational efficiencies. In this research, we propose a variant DenseNet-type neural network (NN) model for modeling PEAs in an AFM scanner where position feedback sensors are not available. To improve the performance of this model, the mapping of the forward and backward directions is carried out separately. The experimental results successfully demonstrate the efficacy of the proposed model by reducing the relative root-mean-square (RMS) error to less than 0.1%. Full article

This work aims to evaluate how the particle size of a waste filler in the form of eggshells changes the mechanical properties of biopoly(ethylene terephthalate) (bioPET). BioPET was modified with three different waste fractions: 1.60–3 mm—large particles; 1.60–1 mm—medium particles; 1 mm–200 μm—small particles. Waste filler was added to the biopolymer matrix in the amount of 10 wt.%. Static tensile tests, as well as bending and impact tests, were carried out to assess the strength properties of the waste-enriched materials. Dissipation energy changes and relaxation processes were observed and evaluated by means of a low-cycle dynamic test. Waste particles were shown to be an effective modifier of bioPET by increasing its stiffness (all particle sizes) and strength (the smallest ones). Studies of the wetting angle and mechanical energy dissipation in the first hysteresis loops indicate the better adhesion of small particles to the biopolymer and their greater ability to dissipate mechanical energy. Full article

To improve the out-of-plane stability of partially encased composite (PEC) beam webs and enhance the synergy between concrete and section steel, a new type of wavy web PEC beam was designed and fabricated. In this study, the flange thickness and shear–span ratio were varied as key parameters. Low-cycle reversed loading tests were conducted to investigate the effects of these variables on the load-bearing capacity, failure patterns, deformation capacity, hysteretic energy dissipation capacity, and stiffness degradation of the wavy web PEC beams. Numerical simulations were performed using ABAQUS CAE2023, a finite element analysis (FEA) software, under low-cycle reversed loading conditions. The applicability of the ABAQUS software CAE2023 for the corrugated web PEC beam model was validated by comparing test results with finite element analysis results. A detailed parametric analysis was then carried out using the finite element model to further investigate the mechanical properties of the wavy web PEC beams. The research findings are as follows: the wavy web PEC beams exhibited good ductility; a larger shear–span ratio led to a transition in the failure pattern from shear failure to flexural failure; varying the flange thickness significantly affected the failure location and characteristics; and reducing the flange thickness could limit the propagation of concrete cracks, thereby improving toughness and energy dissipation capacity. Full article

Magnesium alloys, particularly AZ31, are promising materials for the modern automotive industry, offering significant weight savings and environmental benefits. This research focuses on the challenges associated with accurate modelling of multiaxial cyclic plasticity at small strains of AZ31 under low-cycle fatigue conditions. Current modelling approaches, including crystal plasticity and phenomenological plasticity, have been extensively explored. However, the existing models reach their limits when it comes to capturing the complexity of cyclic plasticity in magnesium alloys, especially under multiaxial loading conditions. To address this gap, a cyclically stable elastoplastic model is proposed that integrates elements from existing models with an enhanced algorithm for updating stresses and hardening parameters, using the hyperbolic tangent function to describe hardening and ensure a stabilised response with closed hysteresis loops for both uniaxial and multiaxial loading. The model is based on a von Mises yield surface and includes a kinematic hardening rule that promises a stable simulation of the response of AZ31 sheets under cyclic loading. Using experimental data from previous studies on AZ31 sheets, the proposed model is optimised and validated. The model shows promising capabilities in simulating the response of AZ31 sheet metal under different loading conditions. It has significant potential to improve the accuracy of fatigue simulations, especially in the context of automotive applications. Full article