Model Calculations Research Articles

Chirality Assisted Triplet Electron Pairing.

Redox processes that involve pairs of electrons are common in nature. Some of these reactions involve oxygen molecules. The understanding of the efficiency of the oxygen reduction reaction (ORR), for example, is a challenge since the reaction is spin forbidden and requires the transfer of two pairs of electrons. Past experimental and theoretical studies demonstrated that by controlling the spin of the transferred electrons, it is possible to overcome the barrier resulting from the spin mismatch between the reactants and the products. In other works, it was suggested that the reaction is enhanced if the two electrons in each pair have phase relation, namely, they possess the property of a triplet state. Since in nature electrons are transferred through chiral systems, we probed if chirality affects the formation of paired electrons with the same spin, namely, a triplet like state. The model calculations demonstrate that chirality enhances the probability of the formation of electron pairing in the triplet states, even at room temperature. This enhancement originates from breaking the spin degeneracy, enabled by chirality and interaction of the spins with vibrations.

Flexural Response of UHPC Wet Joints Subjected to Vibration Load: Experimental and Theoretical Investigation

This study aims to investigate the flexural performance of ultra-high-performance concrete (UHPC) wet joints subjected to vibration load during the early curing period. The parameters investigated included vibration amplitude (1 mm, 3 mm, and 5 mm) and vibration stage (pouring—final setting, pouring—initial setting, and initial setting—final setting). A novel simulated vibration test set-up was developed to reproduce the actual vibration conditions of the joints. The actuator’s reaction force time-history curves for the UHPC joint indicate that the reaction force is stable during the initial setting stage, and it increases linearly with time from the initial setting to the final setting, trending toward stability after 16 h of casting. Under the vibration of 3 Hz-5 mm, cracks measuring 14 cm × 0.2 mm emerge in the UHPC joint. It occurs during the stage from the initial setting to the final setting. The flexural performance of wet joint specimens after vibration was evaluated by the four-point flexural test, focusing on failure modes, load-deflection curves, and the interface opening. The results show that all specimens with joints exhibited bending failure, with cracks predominantly concentrated at the interfaces and the sides of the NC precast segment. The interfacial bond strength was reduced by vibrations of higher amplitude and frequency. Compared with the specimens without vibration, the flexural strength of specimens subjected to the vibration at 3 Hz-3 mm and 3 Hz-5 mm were decreased by 8% and 19%, respectively. However, as the amplitude and frequency decreased, the flexural strength of the specimens showed an increasing trend, as this type of vibration enhanced the compactness of the concrete. Additionally, the calculation model for the flexural strength of UHPC joints has been established, taking into account the impact of live-load vibration. The average ratio of theoretical calculation values to experimental values is 1.01, and the standard deviation is 0.04, the theoretical calculation value is relatively precise.

Research on Two Refined Algorithms for Creep Calculation for Reinforced Concrete Components

Existing refined creep calculation methods primarily include the numerical recursive method. Previous algorithms merely provided a theoretical possibility for refined creep calculations. Their massive computational load, complex derivation processes, and limited applicability conditions made it difficult to apply them practically in engineering. Therefore, this study improves upon existing refined creep algorithms by proposing two new calculation methods: the trapezoidal method and the difference method. The study shows that when calculating creep under different conditions, the proposed methods only require adjustments to certain elements in the calculation model, without the need to re-derive the creep calculation formula; this thus provides a convenient solution for creep calculation under varying operating conditions. Compared to the traditional numerical recursive method, the proposed methods significantly reduce computational effort; compared to the midpoint integration method, the proposed methods offer broader applicability. Under different calculation conditions, both methods exhibit high computational accuracy.

Associated production of J/ψ and direct photon in the parton Reggeization approach

We study the associated J/ψ and direct photon production in the high energy factorization, as it is formulated in the parton Reggeization approach, using two different models for the hadronization of a heavy quark-antiquark pair into a heavy quarkonium, namely the non-relativistic quantum chromodynamics (NRQCD) and the improved color evaporation model (ICEM). We find essential differences in predictions for cross section and transverse momenta spectra obtained using the NRQCD and the ICEM, which can be used for the discrimination between these models. Our prediction for cross sections of the associated J/ψ and direct photon production at the LHC energies slightly overestimate the results early obtained in the next-to-leading order (NLO) calculation in the collinear parton model (CPM). We predict different two-particle correlation spectra in the associated J/ψ and direct photon production which may be interesting for an experimental study

Research on evolution of intellectual property collaborative governance strategies of multi-entities in open source community

ABSTRACT Open source community intellectual property governance is a collaborative activity among multiple entities. This paper starts from the perspective of multi-party collaborative governance, based on evolutionary game theory, using open source community foundations, community operators, and contributors as the game subjects, to construct an evolutionary game model for collaborative intellectual property governance strategy of open source community, digital technology innovation strategies as the core. The correctness of the theoretical analysis was verified through model derivation, calculation, and simulation. The simulation results indicate that digital technology innovation plays an important role in intellectual property governance, and factors such as initial willingness, reward and punishment mechanisms, contribution costs, and infringement risks have a significant impact on the evolution of strategies. Based on this, we propose specific implementation paths to improve the intellectual property governance capacity of open source communities and promote innovative development in open source communities. The research contribution of this paper lies in exploring the process of rule compliance and strategy evolution of multiple subjects in open source communities under the policies guidance and use of digital technology from the use of digital technology innovation, providing new governance tools and governance basis for intellectual property governance in open source communities.

Generalized bond polarizability model for more accurate atomistic modeling of Raman spectra.

Raman spectroscopy is an important tool for studying molecules, liquids and solids. While Raman spectra can be obtained theoretically from molecular dynamics (MD) simulations, this requires the calculation of electronic polarizability along the simulation trajectory. First-principles calculations of electronic polarizability are computationally expensive, motivating the development of atomistic models for the evaluation of the changes in the electronic polarizability with the changes in the atomic coordinates of the system. The bond polarizability model (BPM) is one of the oldest and simplest such atomistic models but cannot reproduce the effects of angular vibrations, leading to inaccurate modeling of Raman spectra. Here, we demonstrate that the generalization of BPM through the inclusion of terms for atom pairs that are traditionally considered to be not involved in bonding dramatically improves the accuracy of polarizability modeling and Raman spectra calculations. The generalized BPM (GBPM) reproduces the abinitio polarizability and Raman spectra for a range of tested molecules (SO2, H2S, H2O, NH3, CH4, CH3OH, and CH3CH2OH) with high accuracy and also shows significantly improved agreement with abinitio results for the more complex ferroelectric BaTiO3 systems. For liquid water, the anisotropic Raman spectrum derived from atomistic MD simulations using the GBPM evaluation of polarizability shows significantly improved agreement with the experimental spectrum compared to the spectrum derived using the BPM. Thus, the GBPM can be used for the modeling of Raman spectra using large-scale molecular dynamics and provides a good basis for the further development of atomistic polarizability models.

Application of multimodal large language models for safety indicator calculation and contraindication prediction in laser vision correction

This study demonstrates the potential of multimodal large language models in calculating safety indicators and predicting contraindications for laser vision correction. ChatGPT-4 effectively analyzed ocular data, calculated key indicators, generated calculator codes, and outperformed traditional machine learning models and indicators in handling unstructured data and corneal topography. Its modality-independent system enabled efficient and accurate data analysis. Despite longer processing times, ChatGPT-4’s performance highlights its potential as a decision-support tool, offering advancements in improving safety.

Transmission Line Icing Prediction Based on Physically Guided Fast-Slow Transformer

To improve the accuracy of the icing prediction model for overhead transmission lines, a physics-guided Fast-Slow Transformer icing prediction model for overhead transmission lines is proposed, which is based on the icing prediction model with meteorological input characteristics. First, the ice cover data is segmented into different time resolutions through Fourier transform; a transformer model based on Fourier transform is constructed to capture the local and global correlations of the ice cover data; then, according to the calculation model of the comprehensive load on the conductor and the conductor state equation, the variation law of ice thickness, temperature, wind speed, and tension is analyzed, and the model loss function is constructed according to the variation law to guide the training process of the model. Finally, the sample mixing enhancement algorithm is used to reduce the overfitting problem and improve the generalization performance of the prediction model. The results show that the proposed prediction model can consider the mechanical constraints in the ice growth process and accurately capture the dependence between ice cover and meteorology. Compared with traditional prediction models such as LSTM (Long Short-Term Memory) networks, its mean square error, mean absolute error, and mean absolute percentage error are reduced by 0.464–0.674, 0.41–0.53, and 8.87–11.5%, respectively, while the coefficient of determination (R2) is increased by 0.2–0.29.

Spatio-Temporal Distribution and Spatial Spillover Effects of Net Carbon Emissions: A Case Study of Shaanxi Province, China

Scientifically evaluating net carbon dioxide (CO2) emissions is the pivotal strategy for mitigating global climate change and fostering sustainable urban development. Shaanxi Province is situated in central China, and boasts robust energy resources in the north and a significant carbon-sink zone in the southern Qinling Mountains. Therefore, uncovering the spatial distributions of net CO2 emissions and identifying its influencing factors across cities in Shaanxi Province would furnish a crucial theoretical foundation for advancing low-carbon development strategies. In this research, the net CO2 emissions of cities in Shaanxi Province from 2005 to 2020 are calculated using the carbon-emission-factor calculation model, then the Geodetector is utilized to evaluate the single-factor explanatory power and two-factor interactions among the fourteen various influencing variables, and then the spatial econometric model is employed to analyze the spatial spillover effects of these key factors. The results show the following: (1) The net CO2 emissions present significant regional differences among the ten cities of Shaanxi Province, notably Xi’an City, Yulin City, and Weinan City, which have recorded remarkable contributions with the respective totals reaching 72.2593 million tons, 76.3031 million tons, and 58.1646 million tons. (2) Regarding temporal trend changes, the aggregate net CO2 emissions across whole province underwent a marked expansion from 2005 to 2019. Yulin City and Shangluo City exhibit remarkable surges, with respective average annual growth rates soaring at 7.38% and 7.39%. (3) From the perspective of influencing factors, GDP exhibits the most pronounced correlation spanning the entire province. Meanwhile, foreign investment emerges as a significant contributor specifically in Xi’an and Yulin City. Moreover, interaction detection reveals most factor combinations exhibit bi-enhancement, while a few exhibits intricate and non-linear enhancement. (4) The SDM regression and fixed-effect analysis reveal that city GDP had a positive spillover effect on neighboring cities’ net CO2 emission, while investment in scientific research and technology services, along with per capita construction land, exhibit notable negative spillovers, suggesting potential emission reduction benefits across cities.

Large-Scale FMO-MP2 Calculations of the Spike Protein Droplet Model.

The spike protein of SARS-CoV-2 is a challenging target for theoretical approaches. Here we report a benchmark calculation of the spike protein droplet model by the fragment molecular orbital (FMO) at the second-order Møller-Plesset perturbation (MP2) level on the supercomputer Fugaku. One hundred structure samples from molecular dynamics (MD) simulations were used for both the closed and open forms of this protein (PDB IDs 6XLU and 6XM0 respectively). The number of total fragments is about 20,000, and the job time per structure was about 2 h on 8 racks of Fugaku.

Evaluation of the onset voltage of water adsorption on Pt(111) surface using density functional theory/implicit model calculations

Evaluation of the onset voltage of water adsorption on Pt(111) surface using density functional theory/implicit model calculations

Characteristics of wind load on high-voltage disconnect switch system in substation

Ensuring high-voltage disconnect switch system safety is essential for the stable operation of the power system. A method for wind force tests to determine the wind load characteristics of the whole and the segments of the disconnect switch system was developed. Through this method, the distributions of aerodynamic coefficients for both the whole structure and its segments were determined, along with the skewed wind load coefficient relative to wind direction. The two-parameter model for wind load was used to predict wind load distribution along the structure's height. The study also considered the effect of different operating states of the disconnect switch system, namely, the switching-off and switching-on states, on wind force coefficients. Comparisons and analyses were performed to examine how these states influence the mean, fluctuating, and peak wind force coefficients, as well as the skewed wind load coefficient of the structure. The results indicate that the calculations of the two-parameter model are in good agreement with the measurements from the segment models. The most critical wind directions for the drag and skewed wind load coefficients for each segment of the structure were found to be 60° and 120°, respectively. Additionally, the mean wind load on the switch and insulator segments was higher than that on the steel columns. The switching-on state was identified as more detrimental to mean and fluctuating wind loads, with a pronounced effect on crosswind and torsional wind loads, especially on the torsional response of the structure.

Three-phase flow induced vibration characteristics for mining riser in deep-sea natural gas hydrate extraction

During the lifting process of deep-sea natural gas hydrate, the mining riser is susceptible to complex fatigue failure due to the combined effects of internal gas–liquid–solid three-phase flow, external ocean loads, and the large aspect ratio of itself. The gas–liquid–solid three-phase flow induced vibration (FIV) model for deep-sea hydrate extraction riser is established using finite element method and Hamiltonian principle. The simulation experimental device for nonlinear vibration of mining riser under internal and external flow excitation is developed and conducted a simulation experiment for gas–liquid–solid three-phase FIV of vertical pipes. The experimental test results are compared with the theoretical model calculation results to verify the correctness of the model. Using frequency domain and time domain analysis methods, the influences of external environmental parameters and multiphase flow parameters on the nonlinear FIV response of the riser are explored. The results showed that the vibration amplitude in the cross-flow (CF) direction of the riser is larger, and the change in internal flow parameters had a more significant impact on the CF vibration. The longitudinal vibration of the riser is composed of low-frequency high-amplitude vibration caused by gravity and platform heave, and high-frequency low-amplitude vibration induced by internal and external flow field loads. The increase in shear flow velocity will significantly increase the displacement of the riser along in-line flow direction, thereby suppressing CF vibration. The research results can be widely applied to the vibration problems caused by gas liquid solid three-phase flow in the energy collection process, which has important research significance and significant engineering value for improving the safety of operation columns.

First-principles calculations of quartz–coesite interfaces

Atomistic interface structures compatible with periodic boundary conditions for the strain-induced subsolidus martensitic transition between quartz and coesite have been investigated. We identified layers of atoms that remained unchanged in terms of neighbor interactions throughout the transformation. Our analysis revealed that the orientation relationships between quartz and coesite, namely (1011)Qz||(010)Coe and (1321)Qz||(010)Coe, are consistent with experimental observations. Using density-functional-theory-based tight-binding model calculations, we determined an interface energy of approximately 660 mJ m−2 for these interfaces and strain energies of 196 (6) and 2760 (160) J mol−1 atom−1 for the (1321)Qz||(010)Coe and (1011)Qz||(010)Coe oriented interfaces, respectively. To visualize these interface structures and facilitate their identification in experiments, we simulated high-resolution transmission electron microscopy images and electron diffraction patterns.

Testing and simulation of the hysteresis characteristics of magnetostrictive materials under harmonic excitation

As various power electronic devices are widely used in the power grid, the current flowing through the drive winding of the magnetostrictive actuator inevitably contains harmonic components. The flux density within the hysteresis material is non-sinusoidal with harmonic components, which distorts the hysteresis characteristics of the material and affects the accurate calculation of losses. This paper builds a harmonic magnetic performance testing platform for magnetostrictive materials to test and analyze the magnetic properties under different excitation conditions (magnetic density amplitude, harmonic order, and harmonic content). To complete the mathematical description of the static hysteresis model containing closed minor hysteresis loops, two pinning coefficients k1(Bn,kTHD) and k2(Bn,kTHD), which are related to the degree of harmonic distortion, are used to express the rate of change of the irreversible magnetization components. Fractional order derivative and harmonic frequency-dependent terms are used to characterize the eddy losses and excess losses mathematically. Finally, the dynamic hysteresis model under harmonic excitation is developed. Comparative analysis of model calculation results and experimental test data shows that the model can not only accurately simulate the distorted hysteresis characteristics but also predict the loss of magnetostrictive materials. This research is of significance to the optimal design and temperature rise analysis of magnetostrictive devices.

Study on the change of the oil-paper insulation’s AC conductivity characteristics based on dielectric response in frequency domain

Oil-immersed power equipment (transformers and high voltage bushings) are key components of power systems. Oil-paper insulation has endured complex and harsh operating conditions when used as a primary insulation system, so it is essential to determine the insulation state of oil-paper insulation system to ensure a stable operation for the power grid. The oil-paper insulation’s conductivity behavior can effectively characterize the degree of insulation deterioration. However, the relationship between the alternating current (AC) and direct current (DC) conductivity behavior for oil-paper insulation systems is still unclear in current research, resulting in limitations in the traditional evaluation model’s application. Therefore, this paper uses oil-paper insulation materials under different aging to carry out relevant research about the changing features of the complex AC conductivity under different test temperature environments. The influence of oil-paper insulation aging, test temperature, and excitation frequency on the complex AC conductivity is verified. Considering the correlation between low-frequency AC conductivity and DC conductivity, the frequency range of AC conductivity is extended by means of frequency temperature and conductance double translation. The temperature dependence of the AC conductivity behavior is defined over a wide frequency test range. The relaxation polarization process dominated the AC conductivity variation law is obtained. The impact of experimental temperature and insulation aging on the cumulative characteristic parameters of AC ionic mobility is clarified. This study theoretically corrects the traditional calculation model for AC conductivity of oil-paper insulation. The bias in conductivity calculations caused by only considering a single relaxation polarization process is eliminated. The conductivity model that can characterize multiple relaxation polarization processes in the dielectric is established. This model provides theoretical support for the later assessment of oil-paper insulation state depending on conductance behavior.

Modelling and optimization of trajectory deviation for compound directional drilling in coal mines

During the sliding mode of compound directional drilling process in coal mines, the inclined angle and azimuth angle need to be changed to minimize the trajectory deviation between the actual trajectory and the designed trajectory. The inclined angle and azimuth angle can be changed by adjusting the tool face angle. In this article, a modelling and optimization method is proposed to obtain optimal tool face angle for sliding mode. Firstly, the gaussian process regression method is employed to build calculation model of trajectory deviation. The optimization model of trajectory deviation consists of the established calculation model of trajectory deviation and the set constraints. Then, the optimal inclination angle and azimuth angle are obtained by solving the constitutive optimization model using an improved particle swarm optimization algorithm. Next, the calculation model of tool face angle is built to represent the relationship between inclination angle, azimuth angle and tool face angle. The optimal tool face angle is calculated based on optimal inclined angle and azimuth angle. Finally, an industrial case study based on the actual drilling data verifies that the proposed method is beneficial to track designed trajectory during drilling process. The proposed method meets the requirements of on-site construction accuracy and ensures the safety and stability of drilling.

Pull-out behavior of glulam connections with glued-in rod loaded parallel to the grain

ABSTRACT Glued-in rod (GiR) is a reliable moment resistant connection method applied in timber structures. To investigate the pull-out performance of GiR connections parallel to the grain in Douglas fir glulam, this article conducted pull-out tests on two types of rods: threaded rods and rebars. The effects of loading condition and anchorage length on the failure mode, pull-out load-carrying capacity, and strain distribution along the anchorage length were studied. The results showed that the specimens suffered four failure modes: bonding failure, yield failure of the steel rod, pull-out failure of the rebar, and splitting failure. The distribution of strain along the anchorage length of the GiR was uneven. The pull-pull specimens exhibited a higher pull-out load-carrying capacity compared to the pull-compression configuration. Additionally, the load-carrying capacity of the GiR connections increased with increasing anchorage length, whereas the average bond strength exhibited a downward trend. Based on test results and existing reference data, a calculation model of the average and standard value of pull-out load-carrying capacity of a single GiR connection parallel to the grain in glulam was proposed.

Scant Evidence for Long-Range Atmospheric Transport of Particle-Bound Benzotriazole Ultraviolet Stabilizers.

Despite benzotriazole UV stabilizers (BT-UVs) being widely used since the 1960s, few empirical data on their atmospheric presence exist. UV-328 was added to the Stockholm Convention on Persistent Organic Pollutants, based in part on model calculations indicating atmospheric long-range transport potential. We investigated the atmospheric occurrence of BT-UVs at multiple sites that differ greatly in their proximity to potential sources. UV-P, UV-328, UV-234, UV-326, UV-329, and UV-327 were quantified in active air samples collected in suburban Toronto, on Saturna Island in the Salish Sea, at Point Petre on Lake Ontario, and in Alert, Nunavut, as well as in XAD-resin based passive air samplers deployed at sites in British Columbia and Quebec. As the most volatile BT-UV, UV-P was present in the gas phase across all sampling locations, with higher concentrations in urban areas. The five less volatile BT-UVs were present only in active air samples from suburban Toronto and were not found above detection limits (0.03-1.7 pg·m-3) anywhere else. Empirical evidence thus does not support model predictions of long-range atmospheric transport of particle-bound BT-UVs. Predictions based on simple model calculations should be supported by empirical data if they are to be used as the basis for regulatory decisions.

Study of proton-induced excitation functions on natGe up to 60 MeV

Abstract The cross sections for the production of medically significant radioisotopes, including 68Ge, 69Ge, 66Ga, 67Ga, 72As and various radioimpurities produced in pure germanium crystal irradiated with 60 MeV protons, were measured. The experiment utilized germanium targets with natural isotopic composition. Irradiation of the targets was performed using a proton beam from the AIC-144 accelerator at the Institute of Nuclear Physics, Polish Academy of Sciences, Krakow. Gamma spectroscopy was conducted with high-purity germanium detectors to measure the gamma-ray emissions from the irradiated targets. This enabled the determination of reaction cross-sections of the produced radionuclides. Additionally, our results were compared with existing literature and TALYS data to validate our findings. Generally, our experimental results align with previous studies, although discrepancies were observed in certain aspects. Specifically, nuclear model calculations and some literature data indicate slightly higher values compared to our findings.