Dynamic Analysis Research Articles

Nonlinear Seismic Analysis of Concrete Dams Using ABAQUS-Based Scaled Boundary Finite Element Method

ABSTRACT The scaled boundary finite element method (SBFEM) is implemented in ABAQUS through the user subroutine interface. The accuracy of the proposed method and computer program are verified by using two benchmark examples. With the coupled SBFEM and standard finite element method (FEM), the dynamic interaction model of concrete dam – reservoir – foundation considering the geometrical nonlinearity of transverse joints is established using the viscous-spring absorbing boundary conditions. The overlaying element technique is applied to define the contact interface of transverse joints. The dynamic characteristics and linear seismic response of the Koyna gravity dam have been analyzed using polyhedral elements. Finally, nonlinear seismic analysis of the NG5 arch dam has been conducted. The calculated results are in good agreement with those of ABAQUS built-in elements. Moreover, numerical examples demonstrate that proposed method has high computational accuracy and can be applied to the dynamic analysis of complex engineering structures.

Calcite e-twins as a tectonic indicator, paleo stress pattern and structural evolution of the Zagros hinterland, SE Iran

Through the examination of calcite twins, this research outlines the tectonic development and paleo stress patterns of the Paleozoic Routshon complex situated in the southeastern segment of the Sanandaj–Sirjan zone, a hinterland region of the Zagros orogeny in southeastern Iran. The study of orogenic phase indicates that the deformation event affecting the southern sector of the Sanandaj-Sirjan zone aligns with the Cimmerian orogenic phase of the Late Triassic period. A variety of structural features at both map and outcrop scales highlight the importance of slip partitioning in the structural evolution of this region, driven by inclined transpression. Observations suggest that the deformation related to contractional components includes steeply to moderately plunging folds, dip-slip domain deformation primarily involving thrusts, and ongoing deformation by strike-slip component motion, which results in thrust-related ductile shear zones. The analysis of calcite c-axis fabrics from mylonite samples obtained from these shear zones indicates a low-temperature monoclinic pattern of non-coaxial deformation. This deformation type underscores the impact of the strike-slip component in the development of progressive simple shear within thrust-related shear zones in this segment of the Sanandaj-Sirjan zone. Dynamic analysis of c-axis fabric data reveals a NE-SW orientation for the principal compressive axes (σ1) in this area. This direction, corroborated by additional data such as fault surface, GPS, and earthquake focal mechanism data, confirms that the orientation of the compressive axes (σ1) has remained consistent from the Late Triassic to the present.

Analytical Framework for Tension Characterization in Submerged Anchor Cables via Nonlinear In-Plane Free Vibrations

Submerged tensioned anchor cables (STACs) are pivotal components utilized extensively for anchoring and supporting offshore floating structures. Unlike tensioned cables in air, STACs exhibit distinctive nonlinear damping characteristics. Although existing studies on the free vibration response and tension identification of STACs often employ conventional Galerkin and average methods, the effect of the quadratic damping coefficient (QDC) on the vibration frequency remains unquantified. This paper re-examines the effect of bending stiffness on the static equilibrium configuration of STACs, and establishes the in-plane transverse free motion equations considering bending stiffness, sag, and hydrodynamic force. By introducing the bending stiffness influence coefficient and the Irvine parameter, the exact analytical solutions of symmetric and antisymmetric frequencies and modal shapes of STACs are derived. An improved Galerkin method is proposed to discretize the nonlinear free motion equations ensuring the accuracy and applicability of the analytical results. Additionally, this paper presents an analytical solution for the nonlinear free vibration response of the STACs using the improved averaging method, along with improved frequency formulas and tension identification methods considering the QDC. Through a case study, it is demonstrated that the improved methods introduced in this paper offer higher accuracy and wider applicability compared to the conventional approaches. These findings provide theoretical guidance and reference for the precise dynamic analysis, monitoring, and evaluation of marine anchor cable structures.

Free Vibration analysis of C/SiC blisk based on modified global mode method

The bladed disk is the core component which is under load in aero-engine, rocket engine and gas turbine. In recent years, the bladed disk has developed towards the direction of integrated bladed disk (blisk) and being applied with ceramic matrix composites. However, there is no accurate semi-analytical dynamic model to describe the dynamic characteristic of ceramic matrix composite blisk. In this paper, a new semi-analytical method, modified global mode method (MGMM) is proposed to model the 2D C/SiC laminated blisk. In proposed method, Chebyshev polynomials series are used to expand the displacements of the blades and disk, constraints between blades and disk is strictly satisfied by multi-modal transformation and integrated into governing equation, and high-order shear deformation theory is combined to establish the dynamic model of the blisk of 2D C/SiC laminated composite material. The proposed method avoids the matrix singular problem appearing in traditional global mode method when modeling of combined structure and makes the system perform dynamic analysis and mode prediction without mode extraction and reconstruction. Then, amplitude frequency response and modal experiment are carried out to verify the correctness and convergence of the proposed method. Finally, under the framework of proposed method, the effects of material parameters and geometric parameters on the modal characteristics of the blisk are analyzed. The results show that compared with the geometric parameters, the material parameters have less influence on the modal characteristics of blisk, additionally, a series of modal steering is observed. The work in this paper can provide theoretical guidance for the dynamic design of composite blisk.

Modelling of Brake Pad Disc with emphasis on dynamic analysis and deformation of structure.

Modelling of Brake Pad Disc with emphasis on dynamic analysis and deformation of structure.

Dynamic analysis and multiple solutions for a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid

Dynamic analysis and multiple solutions for a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid

Empowering young farmers' voices in climate change extension programs: An in-depth analysis of decision-making dynamics and social media engagement

Effective integration of rural communities in climate change extension programs requires a detailed examination of the key factors that shape their participation. This study examines various variables and assesses their influence on young farmers' decision making within climate change extension programs and social media engagement for climate change awareness dissemination in the Hindu Kush Himalayas (HKH), Pakistan. Data were collected from young farmers aged 18–34 years through household surveys and from various government department officials through key informant interviews (KIIs). A bivariate probit regression model and thematic analysis were used to analyze the data. The bivariate probit regression shows that perceived risk and access to climate information positively influence young farmers' decision making in climate change extension programs, while years of education have a negative association. For social media engagement, the bivariate probit regression shows that government program benefits and the number of male members positively influence farmers' participation, while household size has a negative association. The results of our KIIs revealed that positive factors influencing young farmers' engagement in climate change extension programs include geographic ties, dependence on livestock, attitudes toward climate change, and positive perceptions of agriculture. Conversely, barriers include low acreage and productivity, reluctance of elders, lack of political support, and adherence to tradition. This study recommends that to improve young farmers' decision-making in climate change extension programs, there is a need to improve access to climate information and strengthen government support to promote social media engagement.

A Delicate Balancing Act: Integrative Pluralism and the Pursuit of Unified Theories

AbstractThis paper examines the interplay between integrative explanatory pluralism and the quest for unified theories. We argue that when grounded in virtues associated with satisfactory explanations, integrative pluralism exhibits an inherent instability stemming from the conflict between the demand for unity and the commitment to preserving a patchwork of disparate partial explanations. A case study in cognitive science illuminates the challenges of maintaining both systematicity and depth in explanations within this framework. While this instability does not render integrative pluralism fundamentally flawed, it stresses the importance of a diachronic analysis of scientific dynamics and norms. The conclusion highlights the continued value of integrative pluralism in interdisciplinary research programs, while emphasizing its role as a temporary rather than permanent approach.

CPL of Mellein and Related Natural Compounds: Analysis of the ESIPT Phenomenon.

(R)-(-)-Mellein, (3R,4R)-4-hydroxymellein and (3R,4S)-4-hydroxymellein obtained from fungi, i. e. from Diplodia globulosa, were investigated as a class of natural products presenting ESIPT (excited state intramolecular proton transfer) phenomenon, through fluorescence and CPL (circularly polarized luminescence). The study was preceded by the assessment of the absolute configuration through ECD and VCD (electronic and vibrational circular dichroism) spectroscopies in addition to NMR spectra. It is found that ESIPT takes place in these systems very rapidly, and no dual fluorescence has been observed. The experimental study is backed up by TD-DFT calculations of ECD and CPL spectra, plus MD calculations to follow proton transfer in the excited state and careful analysis of the puckering dynamics of the lactone ring. Deprotonated forms of the three compounds were also investigated by the same chiroptical experimental and theoretical methods, showing how one can find in natural compounds not only biological activity but also biologically compatible sensing probes.

Research on Business Model Innovation of Media Industry in the Era of “Internet+”

In the pattern of rapid development of the media industry characterized by the emergence of the “Internet Plus” era, enterprises are facing unprecedented challenges and opportunities. This paper discusses the influence of Internet technology on the media industry, and discusses the strategy of business model innovation to improve competitiveness and adapt to the changing market demand. Through a comprehensive analysis of the changing dynamics of content production, distribution and consumer behavior, this study determines the necessity of media enterprises to innovate business models. By taking advantage of Internet technology, such as resource integration and value creation, media companies can open up new ways of growth and sustainable development. Empirical research shows that enterprises that adopt business model innovation are superior to their traditional counterparts in profitability. Finally, this study provides valuable reference for the media industry stakeholders who seek to master the complexity of the digital age and flourish in the era of “Internet Plus”.

Characterisation of aroma‐active compounds in wheat flour by molecular sensory science

SummaryFour different extraction methods were used to extract aroma compounds from flour. It was found that dynamic headspace sampling (DHS) was a better method for extracting aroma‐active compounds in flour. Hexanal, decanal, butanoic acid, 2,3‐pentanedione, 2‐acetyl‐1‐pyrrolinoline, and 3‐octen‐2‐one were found to be the important aroma‐active compounds in flour by olfaction (O) in two‐dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC‐O‐MS). Dynamic headspace dilution analysis (DHDA), odour activity value (OAV), recombination and omission experiment further verified that these compounds can roughly simulate the overall aroma profile of flour. In this study, we determined the aroma‐active compounds in flour by molecular sensory science to improve the sensory preference of flour and enhance the quality of flour aroma, which will provide analytical ideas for future research on flour aroma and improve the production process.

How to correctly fit an SIR model to data from an SEIR model?

In epidemiology, realistic disease dynamics often require Susceptible-Exposed-Infected-Recovered (SEIR)-like models because they account for incubation periods before individuals become infectious. However, for the sake of analytical tractability, simpler Susceptible-Infected-Recovered (SIR) models are commonly used, despite their lack of biological realism. Bridging these models is crucial for accurately estimating parameters and fitting models to observed data, particularly in population-level studies of infectious diseases.This paper investigates stochastic versions of the SEIR and SIR frameworks and demonstrates that the SEIR model can be effectively approximated by a SIR model with time-dependent infection and recovery rates. The validity of this approximation is supported by the derivation of a large-population Functional Law of Large Numbers (FLLN) limit and a finite-population concentration inequality.To apply this approximation in practice, the paper introduces a parameter inference methodology based on the Dynamic Survival Analysis (DSA) survival analysis framework. This method enables the fitting of the SIR model to data simulated from the more complex SEIR dynamics, as illustrated through simulated experiments.

Exploring the pharmacological potential of Lepionurus sylvestris blume: from folklore medicinal usage to modern drug development strategies using in vitro and in silico analyses

BackgroundLepionurus sylvestris Blume has a long history of folklore medicinal usage against various ailments. However, studies on these plants were neglected particularly their pharmacological potential.MethodsThe crude extract was identified using LC-MS analysis. In vitro assays were carried out to determine the properties of antioxidant, anti-microbial, and anti-cancer. Further, network pharmacology was proposed to evaluate the potential targets of the compounds against breast cancer and type II diabetes. Molecular docking and molecular dynamic simulation were used to determine the potential compounds for the drug formulation of diabetes.ResultsVarious bioactive compounds were identfied using LC-MS and Galiposin, Fujikinetin, Boeravinone B, 4-Deoxybryaquinone, and Norbaeocystin were described for the first time from the plant. Determination of antioxidant potential showed that the IC50 value of ABTS, DPPH, and phosphomolybdate was 24.33 µg/ml, 37.81 µg/ml, 60.35 µg/ml, and reducing power assays 1.185. The antibacterial activity against Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was determined, and the minimum inhibition concentration (MIC) was found to be 5.3 mg/ml, 3.47 mg/ml, 3.33 mg/ml, and 2.7 mg/ml respectively, revealing the extracts as effective antibacterial agents. The IC50 values for the plant extract were determined to be 26 µg/ml, 30.52 µg/ml, and 24.39 µg/ml for HeLa, MCF-7, and K-562 cells, respectively, and the increasing concentration of the plant extract increased LDH release. Furthermore, the in silico network pharmacology, molecular docking which had the highest docking score for GAPDH and HIF-1 target proteins of -9.3 kcal/mol, and − 11.3 kcal/mol binding affinities, and molecular dynamic simulation analysis revealed the bioactive compound Boeravinone B present in the plant was significant for the treatment of various ailments.ConclusionBased on our findings, plant extracts could be a promising option for developing new drug formulations.

A low-mass sub-Neptune planet transiting the bright active star HD 73344

Context. Planets with radii of between 2 and 4 R⊕ closely orbiting solar-type stars are of significant importance for studying the transition from rocky to giant planets, and are prime targets for atmospheric characterization by missions such as JWST and ARIEL. Unfortunately, only a handful of examples with precise mass measurements are known to orbit bright stars. Aims. Our goal is to determine the mass of a transiting planet around the very bright F6 star HD 73344 (Vmag = 6.9). This star exhibits high activity and has a rotation period that is close to the orbital period of the planet (Pb = 15.6 days). Methods. The transiting planet, initially a K2 candidate, is confirmed through TESS observations (TOI 5140.01). We refined its parameters using TESS data and rule out a false positive with Spitzer observations. We analyzed high-precision radial velocity (RV) data from the SOPHIE and HIRES spectrographs. We conducted separate and joint analyses of K2, TESS, SOPHIE, and HIRES data using the PASTIS software. Given the star’s early type and high activity, we used a novel observing strategy, targeting the star at high cadence for two consecutive nights with SOPHIE to understand the short-term stellar variability. We modeled stellar noise with two Gaussian processes: one for rotationally modulated stellar processes, and one for short-term stellar variability. Results. High-cadence RV observations provide better constraints on stellar variability and precise orbital parameters for the transiting planet: a radius of Rb = 2.88−0.07+0.08 R⊕ and a mass of Mb = 2.98−1.90+2.50 M⊕ (upper-limit at 3σ is <10.48 M⊕). The derived mean density suggests a sub-Neptune-type composition, but uncertainties in the planet’s mass prevent a detailed characterization. In addition, we find a periodic signal in the RV data that we attribute to the signature of a nontransiting exoplanet, without totally excluding the possibility of a nonplanetary origin. This planetary candidate would have a minimum mass of about Mc sin ic = 116.3 ± −13.0+12.8 M⊕ and a period of Pc = 66.45−0.25+0.10 days. Dynamical analyses confirm the stability of the two-planet system and provide constraints on the inclination of the candidate planet; these findings favor a near-coplanar system. Conclusions. While the transiting planet orbits the bright star at a short period, stellar activity prevented us from precise mass measurements despite intensive RV follow-up. Long-term RV tracking of this planet could improve this measurement, as well as our understanding of the activity of the host star. The latter will be essential if we are to characterize the atmosphere of planets around F-type stars using transmission spectroscopy.

Application of hybridized ensemble learning and equilibrium optimization in estimating damping ratios of municipal solid waste

The dynamic analysis of municipal solid waste (MSW) is essential for optimizing landfills and advancing sustainable development goals. Assessing damping ratio (D), a critical dynamic parameter, under laboratory conditions is costly and time-consuming, requiring specialized equipment and expertise. To streamline this process, this research leveraged several novel ensemble machine learning models integrated with the equilibrium optimizer algorithm (EOA) for the predictive analysis of damping characteristics. Data were gathered from 153 cyclic triaxial experiments on MSW, which examined the age, shear strain, weight, frequency, and percentage of plastic content. Analysis of a correlation heatmap indicated a significant dependence of D on shear strain within the collected MSW data. Subsequently, five advanced machine learning methods—adaptive boosting (AdaBoost), gradient boosting regression tree (GBRT), extreme gradient boosting (XGBoost), random forest (RF), and cubist regression—were employed to model D in landfill structures. Among these, the GBRT-EOA model demonstrated superior performance, with a coefficient of determination (R2) of 0.898, root mean square error of 1.659, mean absolute error of 1.194, mean absolute percentage error of 0.095, and an a20-index of 0.891 for the test data. A Shapley additive explanation analysis was conducted to validate these models further, revealing the relative contributions of each studied variable to the predicted D-MSW. This holistic approach not only enhances the understanding of MSW dynamics but also aids in the efficient design and management of landfill systems.

Repurposing Antiviral Drugs as Potential Anti-EGFR Agents in NSCLC: A Structure-Based Screening and Molecular Dynamics Analysis.

One of the problems resulting from recurrent hyperactivated or mutant epidermal growth factor receptors (EGFR) in non-small cell lung cancer (NSCLC) is therapeutic resistance. Consequently, this leads to increased expressionof oncogenicproteins and reduces the efficacy of EGFR tyrosine kinase inhibitors (TKIs). This study assessed antiviral drug efficacy as potential anti-EGFR agentsfor NSCLC. We used structure-based virtual screening to evaluate 66 antiviral drugs thoroughly. The top 6 antiviral drugs exhibiting impressive binding energies (i.e. surpassing a threshold of -8.5 kcalmol-1) were identified. Subsequent bioactivity analysis and ADMET profiling were performed to select the most promising candidates, followed by a molecular dynamic simulation. Among the selected antiviral regimens, dolutegravir demonstrated the highest docking score (-9.8 kcalmol-1), followed by rilpivirine and ensitrelvir, surpassing other candidates and our reference EGFR TKI. Further molecular dynamics simulations revealed promising dynamic interactions of dolutegravir, ensitrelvir, and rilpivirine with the EGFR target as compared with afatinib. Our findings highlight the repositioning potential of antiviral drugs for anti-EGFR drug discovery, supported by their robust docking scores, ADMET profiles, dynamic interactions, and binding free energies. The results open up new avenues for advanced NSCLC therapy. Further in vitro investigations are warranted to evaluate their efficacy and safety.

Multidisciplinary Collaborative Design Optimization of Electric Shovel Working Devices

The development of the open-pit mining industry has set higher performance standards for mining electric shovels. Addressing issues such as low efficiency, high energy consumption, and high failure rates in working mining electric shovel devices, this paper comprehensively considers bulk mechanics, structural mechanics, and dynamics to conduct a multidisciplinary, collaborative design optimization for electric shovels by introducing the BLISCO method, which is based on an approximated model, into the structural-optimization design process of working electric shovel devices, aiming to enhance the overall performance of electric shovels. Firstly, a dynamic model of an electric shovel is established to analyze the hoist force and crowd force during the excavation process, and an accurate load input for the dynamic analysis is provided through the bulk material mechanics model. Additionally, to ensure that the stiffness of the boom meets the requirements, the maximum stress at the most critical position of the optimized boom is considered. Subsequently, the design variables are screened through experimental design, and an approximate model is established. Focusing on the hoist force, crowd force, maximum stress at the critical position of the boom, and the angle between the dipper arm and the wire rope, a mathematical model is constructed and optimized using a two-level integrated system co-optimization framework based on an approximate model (BLISCO-AM), followed by a simulation. Finally, a test bench for the electric shovel working device is constructed to compare pre- and post-optimization performance. Experimental results show that through the optimized design, the hoist force and crowd force required in a single excavation process are reduced by 6% and 8.48%, respectively, and the maximum angle between the wire rope and the dipper arm is increased by 4%, significantly improving excavation efficiency while ensuring the safety and reliability of the equipment.

Can β-blockers prevent intracranial aneurysm rupture? - insights from Computational Fluid Dynamics analysis.

Hypertension is a risk factor for intracranial aneurysm rupture. We analyzed whether the intake of drugs from specific classes of anti-hypertensive medications affects hemodynamic parameters of intracranial aneurysm dome. We recorded medical history including medications and the in-hospital blood pressure values. We then obtained 3D reconstruction of each patients' aneurysm dome and the feeding artery. Using OpenFOAM software we performed Computational Fluid Dynamics analysis of blood flow through the modeled structures. Blood was modeled as Newtonian fluid, using the incompressible transient solver. As the inlet boundary condition we used the patient-specific Internal Carotid Artery blood velocity waves obtained with Doppler ultrasound. We calculated haemodynamic parameters of the aneurysm dome. All presented analyses are cross-sectional.We included 72 patients with a total of 91 unruptured intracranial aneurysms. The history of β-blocker intake significantly influenced hemodynamic parameters of aneurysm dome. The patients on β-blockers had significantly smaller aneurysm domes (5.09 ± 2.11 mm vs. 7.41 ± 5.89 mm; p = 0.03) and did not have aneurysms larger than 10 mm (0% vs 17.0%; p = 0.01). In the Computational Fluid Dynamics analysis, walls of aneurysms in patients who took β-blockers were characterized by lower Wall Shear Stress Gradient (1.67 ± 1.85 Pa vs. 4.3 ± 6.06 Pa; p = 0.03), Oscillatory Shear Index (0.03 ± 0.02 vs. 0.07 ± 0.10; p = 0.04) and Surface Vortex Fraction (16.2% ± 5.2% vs. 20.0% ± 6.8%; p<0.01). After controlling for covariates, we demonstrated difference of Surface Vortex Fraction (F[1, 48] = 4.36; p = 0.04) and Oscillatory Shear Index (F[1, 48] = 6.51; p = 0.01) between patients taking and not taking β-blockers, respectively. Intake of β-blockers might contribute to more favorable hemodynamics inside aneurysmal sac. Other antihypertensive medication classes were not associated with differences in intracranial aneurysm parameters.

Dynamical analysis of hearing loss due to mumps virus with Caputo fractional derivative

Mumps is the most common disease for children, which causes hearing loss in all auditory systems. WHO initiated compulsory vaccination for children who are at age of 12 months to 12 years, since 1967. Children must take two doses of vaccination for mumps. The dynamics of the system describing the mumps transmission is studied in this work. The main aim is to elucidate the nonlinear behavior of the system which can provide insights into the long-term effects of Mumps infection on auditory function. As the fractional-order derivative preserves the impact of system memory, we employ the Caputo fractional derivative as the dynamical system describing modeling to simulate hearing loss in children brought on by the mumps virus. The boundedness existence of the solution and stability analysis of the dynamical system are derived in the framework. The result is derived using a well-known numerical method to capture the corresponding consequences and predict the future consequence of the dynamical system associated with parameters. To testify to the importance of the generalizing classical model with a fractional operator, we plot 2D graphs. This study helps to researcher beginners to understand the essential and fundamental tools while investigating real-world problems.

Nonlinear dynamic analysis of shear- and torsion-free rods using isogeometric discretization and outlier removal

AbstractIn this paper, we present a discrete formulation of nonlinear shear- and torsion-free rods introduced by Gebhardt and Romero (Acta Mechanica 232(10):3825–3847, 2021) that uses isogeometric discretization and robust time integration. Omitting the director as an independent variable field, we reduce the number of degrees of freedom and obtain discrete solutions in multiple copies of the Euclidean space $$\left( \mathbb {R}^3\right) $$ R 3 , which is larger than the corresponding multiple copies of the manifold $$\left( \mathbb {R}^3 \varvec{\times } S^2\right) $$ R 3 × S 2 obtained with standard Hermite finite elements. For implicit time integration, we choose the same integration scheme as Gebhardt and Romero in (2021) that is a hybrid form of the midpoint and the trapezoidal rules. In addition, we apply a recently introduced approach for outlier removal by Hiemstra et al. (Comput Methods Appl Mech Eng 387:114115, 2021) that reduces high-frequency content in the response without affecting the accuracy, ensuring robustness of our nonlinear discrete formulation. We illustrate the efficiency of our nonlinear discrete formulation for static and transient rods under different loading conditions, demonstrating good accuracy in space, time and the frequency domain. Our numerical example coincides with a relevant application case, the simulation of mooring lines.