Curve Diagrams Research Articles

Linearity of natural versus laboratory-imparted remanence demagnetization diagram and reliability of relative paleointensity estimation

Information on geomagnetic field intensity in the past is essential for understanding the behavior and mechanism of the geodynamo. A fundamental unresolved problem of relative paleointensity (RPI) estimations from marine sediments is that changes in the constituents of magnetic mineral assemblages may influence RPI estimations, called lithological contamination. A negative correlation between RPI and the ratio of anhysteretic remanent magnetization (ARM) susceptibility to saturation isothermal remanent magnetization (kARM/SIRM), which is a proxy for the proportion of magnetofossils to detrital magnetic minerals, was previously reported from deep-sea sediments. This could be caused by lower RPI recording efficiency of the magnetofossil component than the detrital component. To elaborate further this issue, we have conducted a paleo- and rock magnetic study of a sediment core taken from the central north Pacific. RPI estimated from a slope in a diagram plotting a pair of natural remanent magnetization (NRM) and ARM at each alternating-field demagnetization step (NRM-ARM demagnetization diagram) has a negative correlation with kARM/SIRM. Principal component analysis of first-order reversal curve diagrams indicates a downcore increase of the magnetofossil proportion with increased kARM/SIRM. These results reinforce the lower RPI recording efficiency of magnetofossils. In this core, the magnetic coercivity ranges of the magnetofossil and detrital components overlap, which produces a linear NRM-ARM demagnetization diagram. This hinders a possibility of obtaining uncontaminated RPI from a coercivity window representing the magnetofossils or detrital magnetic components, which was tried by some previous studies. A linear NRM-ARM demagnetization diagram, which was sometimes used as a criterion of reliable RPI estimations, does not necessarily mean the absence of lithological contamination to the RPI. In sediments with changing proportion of magnetofossils, normalization with IRM may work better than ARM.Graphical

FORCINN: First‐Order Reversal Curve Inversion of Magnetite Using Neural Networks

AbstractFirst‐order reversal curve (FORC) diagrams are a standard rock magnetic tool for analyzing bulk magnetic hysteresis behaviors, which are used to estimate the magnetic mineralogies and magnetic domain states of grains within natural materials. However, the interpretation of FORC distributions is challenging due to complex domain‐state responses, which introduce well‐documented uncertainties and subjectivity. Here, we propose a neural network algorithm (FORCINN) to invert the size and aspect ratio distribution from measured FORC data. We trained and tested the FORCINN model using a data set of synthetic numerical FORCs for single magnetite grains with various grain‐sizes (45–400 nm) and aspect ratios (oblate and prolate grains). In addition to successfully testing against synthetic data sets, FORCINN was found to provide good estimates of the grain‐size distributions for basalt samples and identify sample size differences in marine sediments.

A Numerical Study of Concrete Composite Circular Columns encased with GFRP I-Section using the Finite Element Method

This paper presents ABAQUS simulations of fully encased composite columns, aiming to examine the behavior of a composite column system under different load conditions, namely concentric, eccentric with 25 mm eccentricity, and flexural loading. The numerical results are validated with the experimental results obtained for columns subjected to static loads. A new loading condition with a 50 mm eccentricity is simulated to obtain additional data points for constructing the interaction diagram of load-moment curves, in an attempt to investigate the load-moment behavior for a reference column with a steel I-section and a column with a GFRP I-section. The result comparison shows that the experimental data align closely with the simulation results regarding the ultimate strength, deformation, and failure modes, thereby validating the accuracy of the considered models. On the other hand, the numerical results of the column specimens under 50 mm eccentric load demonstrated that, in that case, the ultimate load of the columns decreased. The capacity of the reference column, a column with steel I-section, and a column with GFRP I-section decreased to 67%, 63%, and 64%, respectively compared with the columns tested under concentric load. The analytical investigation predicted the load-carrying capacity and bending moment capacity of the specimens with good accuracy. Based on the experimental curves, and the high strength found in the specimens that use the steel I- and GFRP I-sections, a good agreement between the numerical simulation and the experimental results was noticed.

Prediction of fuel consumption and shaft torque using machine learning and analysis of engine curve diagrams

Prediction of fuel consumption and shaft torque using machine learning and analysis of engine curve diagrams

Risk factor analysis and prediction of multi-organ metastasis in hepatic alveolar echinococcosis.

Patients with multiple organ metastases from hepatic alveolar echinococcosis have a high mortality rate. However, predictors of multi-organ metastasis have not been identified. We aimed to develop a nomogram that predicts multi-organ metastasis in patients with hepatic alveolar echinococcosis. We retrospectively screened patients with hepatic alveolar echinococcosis who were treated between January 2016 and December 2021 at Qinghai Provincial People's Hospital, China. The outcome of the nomogram was multi-organ metastasis of hepatic alveolar echinococcosis. We collected patients' basic characteristics, disease course, imaging, and blood laboratory results. The Least Absolute Shrinkage Selection Operator (LASSO) analysis selected the predictors preliminarily. A predictive model was constructed by multivariate logistic regression and presented as a nomogram. The performance of the nomogram was measured by the receiver operating characteristic (ROC) curve, calibration diagram, and decision curve analysis (DCA). The model was internally validated by calculating the performance of the validation cohort. A total of 353 patients were enrolled in this study. Ninety five (26.9%) patients presented with multi-organ metastases. All participants were randomized into a development cohort (n = 249) and a validation cohort (n = 104). Predictors in this nomogram were the course of the disease, the long diameter of the lesion, multiple intrahepatic lesions, and medication. The ROC curve of the training set was 0.907 (95% CI: 0.870, 0.943). A similar ROC curve was achieved at the validation set (0.927, 95% CI: 0.876, 0.979). The calibration curve demonstrated that the prediction outcome was correlated with the observed outcome. The nomogram can predict the risk of multi-organ metastasis in patients with hepatic alveolar echinococcosis, and help clinicians develop or adjust a reasonable diagnosis and treatment plan in time.

Revisiting the BE99 method for the study of outflowing gas in protostellar jets

An established method for measuring the hydrogen ionisation fraction in shock-excited gas is the BE99 method, which utilises six bright forbidden emission lines: S\,II N\,II 6583, and O\,I 6363. The main assumptions of this technique are that the gas is in a low-excitation state ($x_ e < 0.3$) and that the equilibrium of the underlying ionisation network is reached. Our aim is to extend the BE99 method by including more emission lines in the blue and near-infrared part of the spectrum ($ and by considering higher hydrogen ionisation fractions ($x_ e > 0.3$). In addition, we investigate how a non-equilibrium state of the gas and the presence of extinction influence the BE99 technique. We numerically solved a network of ionisation reactions in the time domain, which lead to the BE99 equilibrium. We applied the BE99 method on synthetic spectra also in the non-equilibrium state. We extented the BE99 technique to higher ionisation fractions by considering additional reactions, which involve higher ionisation states of oxygen, nitrogen, and sulphur. We tested our concepts on the low-excitation outflow of Par Lup 3-4 and the high-excitation 244-440 Proplyd in Orion. Many additional emission line ratios can in principle be exploited as extended curves (or stripes) in the ($x_ e T_ e $) diagram. If the BE99 equilibrium is reached and extinction is corrected for, all stripes overlap in one location in the ($x_ e T_ e $) diagram indicating the existing gas parameters. We find that the BE99 equilibrium is reached faster than the hydrogen recombination time. The application to the Par Lup 3-4 outflow shows that the classical BE99 lines together with the N\,I lines do not meet in one location in the ($x_ e T_ e $) diagram. This indicates that the gas parameters derived from the classical BE99 method are not fully consistent with other observed line ratios. A multi-line approach is necessary to determine the gas parameters. From our analysis we derive $n_e cm cm $, $T_e = 7\,600\ K K $, and $x_e 0.027-0.036$ for the Par Lup 3-4 outflow. For the 244-440 Proplyd we were able to use the line ratios of S\,II O\,I and OII 7330 in the BE99 diagram to estimate the ionisation fraction at knot E3 ($x_e = 0.58 The BE99 method can be extended by utilising more emission line ratios in the ($x_ e T_ e $) diagram and considering higher ionisation states. Exploiting new line ratios reveals more insights on the state of the gas. Our analysis indicates, however, that a multi-line approach is more robust in deriving gas parameters, especially for high-density gas.

Research on vertical vibration characteristics of rolling mill based on magnetorheological fluid damper absorber

Research on vertical vibration characteristics of rolling mill based on magnetorheological fluid damper absorber

Study of bistability and hyperchaos in a coupled class‐B laser system

AbstractA coupled class‐B laser system is presented to obtain a nonlinear emitter. Its bistability was theoretically predicted, and numerically illustrated to demonstrate by a typical bistable curve diagram. The bistable system exhibits some typical nonlinear dynamic behaviours, such as hyperchaos, quasi‐period as well as coexistent scenarios, and shows a route to a single‐period away from hyperchaos. The hyperchaotic states are diagnosed to find by Lyapunov exponent. The hyperchaotic four‐scroll strange attractor was illustrated to be characterized by ergodicity, complexity, and randomness. The result has a reference value for a bistable optical device, a hyperchaotic emitter, and their applications.

Predicting two-year return-to-sport failure after medial patellofemoral ligament reconstruction in patellar dislocation patients with bone abnormalities.

To develop a comprehensive and validated personalized scoring system based on anatomical characteristics to predict the probability of failure to return to sport after medial patellofemoral ligament reconstruction in patients with patellar dislocation. 312 patients with medial patellofemoral ligament reconstruction in our hospital from 2013 to 2023 were included. Demographic and anatomical characteristics were collected retrospectively. A backward stepwise approach was used to identify independent predictors, and a nomogram was constructed to predict the probability of recurrence. The predictive performance was evaluated by receiver operating characteristic curves, calibration diagram and decision curve analysis. Multivariate analysis showed that increased tibial tubercle-trochlear groove (TT-TG) distance, trochlear dysplasia, increased femoral anteversion angle, and patellar alta were independent risk factors for failure of return to sport after medial patellofemoral ligament reconstruction. Validation of this column graph in the training cohort and validation cohort showed strong predictive power, with areas under the curve of 0.850 and 0.844, respectively. The nomogram has good calibration and good clinical practicability. The study developed a personalized predictive nomogram with 4 predictors (increased TT-TG distance, trochlear dysplasia, increased femoral anteversion angle, and patellar alta) that allowed surgeons to stratify the risk of failure to return to sport after medial patellofemoral ligament reconstruction and recommend skeletal surgery for patients with these factors. Level III.

Simulation and experimental study of aerodynamic characteristics of a rotor adsorption wall-climbing robot

Abstract High-rise buildings are prone to gusts of wind, especially crosswinds. In order to investigate the effect of crosswinds on the aerodynamic characteristics of rotor blades at different near-wall distances, a CFD simulation model is designed for four near-wall distances and five wind speeds, and the change curves of rotor pulling force, pressure cloud diagrams and velocity cloud diagrams are obtained by using Fluent for the various conditions. The mechanism and pattern of its influence on the aerodynamic characteristics of rotor blades are studied by observing the pulling force change curve and cloud diagram. Finally, an experimental platform is built to verify the correctness of the simulation results. The simulation and experimental results have a similar law, i.e., crosswinds do not only have a negative effect on reducing the pulling force generated by the rotor blades, but can also have a gain effect on the pulling force in some cases. This law has some application value, which can be utilized to compensate the rotor speed accordingly. When the pulling force is reduced, the speed is increased appropriately to improve the reliability of the adsorption, and when the pull force is increased, the speed is reduced appropriately, which can reduce the power consumption and increase the range.

Clustering First-order reversal curve diagram using the Gaussian mixture model and the Davies–Bouldin index

Abstract In our energy-consuming society, understanding magnetization reversal in permanent magnets is crucial for improving energy conversion efficiency between electric energy and mechanical energy. First-order reversal curves (FORCs) have enabled qualitative studies of reversal mechanisms, however, further understanding based on quantitative analysis is still difficult due to the complexity of FORC diagrams. We introduce a machine-learning-based approach combining the Gaussian mixture model and the Davies–Bouldin index to separate characteristic features in FORC diagrams of Nd-Fe-B magnets. The clustering method is evaluated using several FORC diagrams obtained at different temperatures, and we also demonstrated hysteresis loop reconstruction using the clustered FORC diagrams.

Calculation of the Critical Liquid Production of Cyclic Steam Stimulation in Heavy Oil Reservoir with Edge Water

Abstract For heavy oil reservoirs with edge water, when the liquid production of cyclic steam stimulation is excessively high, there is a risk of edge-water invasion. Therefore, the liquid production of cyclic steam stimulation is of great significance to the prevention of edge-water invasion in heavy oil reservoir with edge water. Currently, many studies on the critical liquid production in oil reservoir by water flooding are conducted. However, there is few research on the critical liquid production in heavy oil reservoir by cyclic steam stimulation. To fill this gap, The formation after cyclic steam stimulation is divided into the heated zone and the unheated zone. A characterization method for the flow field parameters after cyclic steam stimulation is established. By transforming the length of the thermal swept zone, the comprehensive mobility of the heated zone is equivalently represented as the comprehensive mobility of the unheated zone. On this basis, considering the threshold pressure gradient in heavy oil, a calculation method for the critical liquid production after cyclic steam stimulation in oil reservoir is developed based on the theory of mirror reflection and the superposition of potentials. The results show: (1) Permeability being constant, the critical liquid production rate increases with the increase in cyclic steam injection quality. With a constant cyclic steam injection quality, the critical liquid production rate increases with the increase in permeability; (2) Guided by the established relationship curve diagram between critical liquid production and crude oil mobility, the development plan is designed. As a result, the comprehensive water cut in the oilfield is 8.1%, and no water invasion has occurred; (3) Guided by the established relationship curve diagram between the cumulative liquid production and cumulative heat injection corresponding to different critical liquid production rates, adjustments were made to the oilfield development plan. As a result, the critical liquid production rate for well A1 increased from 110 t/d in the first cycle to 150 t/d in the second cycle.

Formation and preservation mechanisms of magnetofossils in the surface sediments of muddy areas in the yellow and Bohai Seas, China

Formation and preservation mechanisms of magnetofossils in the surface sediments of muddy areas in the yellow and Bohai Seas, China

Carbon Dots Employed for the Detection of Ranitidine and Elaborating the Detecting Mechanism.

Carbon dots (CDs) has been widely utilized in multiple fields, especially towards kinds of drug analyses, owing to its superior optical properties and satisfactory stability. Herein, we rapidly synthesized one kind of soluble bright-blue fluorescent CDs through a facile microwave method, while disodium ethylenediaminetetraacetic acid and phosphoric acid served as the raw materials. Importantly, introducing ranitidine into these CDs resulted in its decreased fluorescence, and thus an innovative method of detecting ranitidine was successfully established, which showed the favorable selectivity and anti-interference ability. With the optimal conditions, the standard curve diagram of F0/F against concentration of ranitidine was linear in the range of 6-2000 µM with a correlation coefficient of 0.9833, and the limit of detection (LOD) was calculated to be 4.2 µM. Meanwhile, we also explored the detecting mechanism of ranitidine by CDs, and elaborated that as the internal filtration effect. Consequently, we may broaden the avenues of detecting ranitidine on the basis of CDs.

Rapid Identification of Greigite in Lacustrine Sediments Using SIRM/χ and χARM: Insights From the Cuo E Core, Tibetan Plateau, China

AbstractThe Cuo E (CE) core contains the entire Quaternary stratigraphy of the CE Lake (31°24′–31°.32′ N, 91°28′–91°33′E, Tibetan Plateau, China). Here, we study the magnetic properties of 1,748 samples from the CE core, combined with scanning electron microscopy and X‐ray energy dispersive spectrometer analysis on selected samples. The main magnetic minerals appear to be magnetite and greigite. To further quantify the presence of greigite in CE core, 84 samples were analyzed using rock magnetism in more detail including: susceptibility (χ) versus temperature, coercivity component analysis of acquisition curves of the isothermal remanent magnetization (IRM), and principal component analysis of the first‐order reversal curve (FORC) diagrams. The greigite content and saturation IRM over susceptibility (SIRM/χ) appear to be exponentially related. SIRM/χ can be used as greigite concentration indicator. We also propose a rapid way to identify greigite in the CE core: When SIRM/χ increases and anhysteretic remanent susceptibility (χARM) increases only slowly, the sample contains greigite. Samples with SIRM/χ < 15 kA/m also follow this relation. This greigite detection method has a lower limit of detection than the traditionally used SIRM/χ parameter. It is also faster than FORC analysis and thus particularly suitable for analysis of large sample collections. Twenty greigite‐bearing layers were identified in the CE core using this method. The location of the Jaramillo subchron in the CE core is controversial in the currently available magnetostratigraphy, possibly related to the presence of greigite in this core interval.

Scaling Properties of Liquid Dynamics Predicted from a Single Configuration: Pseudoisomorphs for Harmonic-Bonded Molecules.

Isomorphs are curves in the thermodynamic phase diagram of invariant excess entropy, structure, and dynamics, while pseudoisomorphs are curves of invariant structure and dynamics, but not of the excess entropy. The latter curves have been shown to exist in molecular models with flexible bonds [Olsen, A. E. J. Chem. Phys. 2016, 145, 241103]. We here present three force-based methods to trace out pseudoisomorphs based on a single configuration and test them on the asymmetric dumbbell and 10-bead Lennard-Jones chain models with bonds modeled as harmonic springs. The three methods are based on requiring that particle forces, center-of-mass forces, and torques, respectively, are invariant in reduced units. For each of the two investigated models we identify a method that works well for tracing out pseudoisomorphs, but these methods are not the same. Overall, we find that the more internal degrees of freedom there are in the molecule studied, the less they appear to affect the gross dynamical behavior. Moreover, the "internal" degrees of freedom (including rotation) do not significantly affect the scaling behavior of the dynamical/transport coefficients provided some 'quenching' is performed.

Mechanical and physical properties of epoxy/SiC composites simulated

This study aimed to predict the mechanical properties of SiC-reinforced epoxy. The cross-linked reinforced epoxy was simulated using Material Studio 7.0 (Accelrys, Inc.). Various percentages of SiC (0, 4, 6, 8, and 10) wt% were used in the simulations. A density curve and cell size diagram are obtained from MD simulations of SiC-epoxy nanocomposites. Under a 0.5 GPa pressure, Forcite dynamic simulations showed that amorphous cells have densities that are close to epoxy density (1.2 g cm−3). Simulations have shown that epoxy/SiC composites respond well to a variety of mechanical strains. Increasing the SiC weight percentage increases the stiffness matrix coefficient of epoxy composites, which is demonstrated by increased stiffness matrix coefficients. Computational studies of epoxy/SiC composites have suggested up to 10% SiC nanoparticles by weight will maintain the epoxy matrix’s density in industrial applications.

Nonlinear dynamics modeling and analysis of aviation drilling actuator feed system considering assembly error

Nonlinear dynamics modeling and analysis of aviation drilling actuator feed system considering assembly error

Enhancing multi-plane light conversion orbital angular momentum multiplexer performance via error analysis.

We present what we believe to be a novel orbital angular momentum (OAM) multiplexing apparatus capable of handling topological charges ranging from l = 0 to ±3 through multi-plane light conversion (MPLC) across four phase planes. Nevertheless, the fabricating process of MPLC devices is prone to errors that cannot be avoided. Our investigation primarily delves into the repercussions of misalignment and etching inaccuracies on the device's phase, with the assistance of a spatial light modulator. The scrutiny of fabrication errors associated with the device offers valuable insights for refining the fabricating of MPLC devices. The OAM multiplexing device converts the phase of MPLC onto a glass substrate through four etching steps, corresponding to a depth of 0-775 nm. OAM multiplexing/demultiplexing crosstalk based on MPLC is less than -20 dB and -18 dB, respectively. The insertion loss of the OAM mode generated by the OAM multiplexing device coupled to the few-mode fiber is less than 7 dB. In a communication experiment, we demonstrated multiplexed three OAM channels carrying 10 Gbit/s OOK signals over a 5 km few-mode fiber using two MPLC devices. Both the bit error rate curve and constellation diagram demonstrate the excellent performance of MPLC-based OAM multiplexing devices in communication networks.

Quantitative Evaluation of China’s Biogenetic Resources Conservation Policies Based on the Policy Modeling Consistency Index Model

Biogenetic resources are the foundation of biodiversity and are of great significance to the sustainability of human society. The effective promotion of biogenetic resource conservation depends on the scientific formulation and implementation of relevant policies, so the quantitative evaluation of biogenetic resource conservation policies can provide decision support for the next step of policy formulation. Based on text analysis, social network analysis, and the construction of the PMC index model, this study selected 132 policy samples issued by the Chinese government in the field of biogenetic resources, established an evaluation system for China’s biogenetic resources policies, which contains 10 first-level indicators and 55 s-level indicators, and drew the PMC curve diagram accordingly to quantitatively evaluate China’s biogenetic resources policies. The results show that China’s biogenetic resources policies are generally at a good level, which can meet the current practical needs of biogenetic resources conservation, but there are problems such as the lack of policy forecasts in the relevant policy texts, the lack of flexible planning in the short and medium term, the lack of co-operation among the policy issuers, and the insufficient guidance of innovation. Based on the results, this article puts forward suggestions for improving China’s biogenetic resource conservation policies.