Analysis Of Dynamical Systems Research Articles

Dynamical behavior-based approach for the evaluation of treatment efficacy: The case of immuno-oncology.

Sophistication of mathematical models in the pharmacological context reflects the progress being made in understanding physiological, pharmacological, and disease relationships. This progress has illustrated once more the need for advanced quantitative tools able to efficiently extract information from these models. While dynamical systems theory has a long history in the analysis of systems biology models, as emphasized under the dynamical disease concept by Mackey and Glass [Science 197, 287-289 (1977)], its adoption in pharmacometrics is only at the beginning [Chae, Transl. Clin. Pharmacol. 28, 109 (2020)]. Using a quantitative systems pharmacology model of tumor immune dynamics as a case study [Kosinsky et al., J. Immunother. Cancer 6, 17 (2018)], we here adopt a dynamical systems analysis to describe, in an exhaustive way, six different statuses that refer to the response of the system to therapy, in the presence or absence of a tumor-free attractor. To evaluate the therapy success, we introduce the concept of TBA, related to the Time to enter the tumor-free Basin of Attraction, and corresponding to the earliest time at which the therapy can be stopped without jeopardizing its efficacy. TBA can determine the optimal time to stop drug administration and consequently quantify the reduction in drug exposure.

A dynamic system analysis study on the design of high-performance pervious concrete ratios

Abstract As permeable concrete contains more pores and larger pore size when improving its water permeability, it will affect its mechanical properties and durability, so it is of great significance to study the mixing ratio of porous concrete. Studying the mixing ratio of porous concrete is of great significance. The subject is studied in depth from the aspects of mechanical properties and water permeability, in order to prepare high-performance permeable concrete with high compressive strength and meet the requirements of infiltration. Firstly. Optimization of the performance of raw materials and mixing ratios of porous concrete, according to the aggregate gradation, aggregate particle size, and other factors on the mechanical properties of porous concrete, to determine its optimal aggregate mixing ratio. Three groups of high-performance pervious concrete specimens with different aggregate particle sizes and pore structures were examined for their real fine structure. Finally, after the preparation of high-performance pervious concrete was completed, the porosity, fractal dimension, equivalent diameter, contour coefficient, and roundness of the specimens were tested to investigate the effects of several factors mentioned above on the permeability coefficient and compressive strength properties of pervious concrete. The results show that the two-dimensional pore diameter is normally distributed, the diameter size is centrally distributed in the range of 0~10mm, and the number of pores in this range accounts for more than 70%. Gradually increasing aggregate particle size leads to an increase in the proportion of large pores inside the specimen. After the compressive strength test and porosity test, it was found that the water permeability coefficient of the porous concrete was the best for the single-grain limestone aggregate with the equivalent diameter range of 5~8mm. The results of this study have theoretical value in enriching and developing high-performance permeable concrete.

Dynamic system employed for predicting noise emission at new constructed mineral ore processing plant

Abstract The impact of noise can arise from the operation of a mineral ore processing plant in the mining industry, such as PT Freeport Indonesia. The use of advanced technology in modern industry, like SAG#3, has increased production productivity but can also lead to noise emission issues that may endanger workers’ health. This research aims to project the impact of noise in the workplace at a new mineral ore processing plant using dynamic system analysis. Noise sampling was conducted using a sound level meter instrument following SNI 7231:2009. After data collection, dynamic system analysis was performed using Vensim Pro software, involving steps such as causal loop design, stock flow diagram formation, and model verification testing. The analysis results indicate that the noise level exceeds the permissible exposure limit, measuring at 85 dBA. Therefore, the implementation of a Hearing Conservation Program (HCP), personal protective equipment (PPE) policies, and periodic noise control policy evaluation are crucial steps in reducing the impact of noise on employees. This study highlights the need for concrete actions by the company, such as improving the effectiveness of the HCP, enforcing stricter PPE policies, and conducting regular evaluations. Consequently, the company can create a safer work environment and reduce the health risks associated with noise exposure in the workplace.

Designing for Dynamics in Dynamic Narrative Inquiry

This article addresses the question “How is dynamic narrative inquiry dynamic?” To do that, I present principles of dynamic narrative inquiry, with a focus on the active authoring of meaning in research interactions as in everyday life. Drawing on prior examples of activity-meaning system research designs and dynamic narrative analyses, I illustrate how this authoring process involves creative use of language and literary forms to express and transform interactive meaning with diverse others and one’s self. A goal of the article is to increase researchers’ sensitivity to the fact that paying attention to how everyone communicates offers major and otherwise overlooked insights into what everyone is saying about the issue of interest.

Absolutely Continuous Invariant Measures for Piecewise Expanding Chaotic Transformations in R^n with Summable Oscillations of Derivative

This paper presents a detailed investigation of absolutely continuous invariant measures (ACIMs) for piecewise expanding chaotic transformations in , with particular attention paid to the case where the derivative has summable oscillations. ACIMs are important objects in the study of dynamical systems, as they provide a way to understand the long-term behavior of trajectories and the statistical properties of the system. The paper covers a range of important topics related to ACIMs, including the boundedness condition, distortion condition, localization condition, and Schmitt's condition. It also discusses the Perron-Frobenius operator, which plays a critical role in the existence and properties of ACIMs. The main result of the paper is the proof that the Perron-Frobenius operator is constrictive, which implies the existence of a finite number of ergodic ACIMs that satisfy Schmitt's condition and a condition dependent on the defining partition. This finding has significant implications for the understanding of complex systems and the advancement of research in this field. The paper also discusses the relationship between ACIMs and dynamical systems, highlighting the role of ACIMs in ergodic theory. Overall, this paper provides a valuable reference for researchers interested in the study of ACIMs and their significance in the analysis of dynamical systems and ergodic theory.

Dynamic responses analysis of crane-blade coupling system for the single blade installation of offshore wind turbine considering the wind effect

The single blade installation method for large-scale offshore wind turbine has the advantage of reduced deck and crane requirements on the installation vessel. Accurately simulating the coupled dynamic responses of the system throughout the entire hoisting process is crucial to avoid spatial interference with surrounding structures. Additionally, the aerodynamic loads, particularly the turbulent wind with spatiotemporal non-uniformity, further aggravate the uncertainty of the dynamic responses. Therefore, a numerical model capable of comprehensive analysis of mechanical-hydrodynamic-aerodynamic-control is urgently needed. However, it is challenging for the commercial software to achieve the coupling analysis. In this paper, the hoisting process is investigated by jack-up installation vessel, so the influence of wave loads on the structure is not considered. The aerodynamic loads are firstly calculated by the blade element theory, and then the numerical model is established by the Lagrangian method, finally the analysis program is developed in MATLAB. The accuracy of the program is verified by code-to-code, and the interaction between the ship-mounted crane and aerodynamic loads during the hoisting process are analyzed. The results show that the aerodynamic loads should be considered during the hoisting of the blade, and the established program could determine the trajectory of the blade inputting the sea state, which can avoid the possible collisions with the surrounding structures.

Enhancing Color Image Security: Encryption with Dynamic Chaotic Three-Dimensional System and Robust Security Analysis

The rapid tech growth and widespread internet usage caused a surge in sharing multimedia (text, images, videos, audio) across public networks. Protecting this data is vital, demanding encryption to prevent unauthorized access. Image encryption distorts images for security. This paper highlights encryption's vital role in safeguarding multimedia, especially amid rising internet use and media exchange. It introduces a novel solution: a chaotic three-dimensional system for color image encryption. The study scrutinizes system traits using math software. It employs a new chaotic system to generate a crucial key sequence for pixel scrambling. Utilizing stream cipher encryption enhances security. Extensive security analysis tests its resilience against attacks like histogram and correlation techniques. Results are promising: a fairly uniform histogram, minimal correlation among pixels nearing zero, and entropy close to the ideal. Metrics like NPCR and UACI almost match ideal values, ensuring high security. Experiments confirm its effectiveness in encrypting diverse color images. The approach guarantees a uniform histogram, minimal pixel correlation nearing zero, entropy near the ideal value (8), and NPCR/UACI values close to ideals (99.61191% and 33.41068% respectively).

Physical modeling and dynamic characteristics of pumped thermal energy storage system

Pumped thermal energy storage (PTES) technology offers numerous advantages as a novel form of physical energy storage. However, there needs to be a more dynamic analysis of PTES systems. This paper proposes a dynamic simulation model of the PTES system using a multi-physics domain modeling method to investigate the dynamic response of key system parameters during the system's start-up and variable operating conditions. Additionally, the impact of equipment parameters on system characteristics was analyzed. Furthermore, a comparative analysis was conducted to assess the variation in system characteristics when considering the different working medium properties. The results show that the system cavity volume should be selected as 5 m3, and the initial pressure of the system during the charge/discharge period should be selected as 2.1 MPa and 3.8 MPa, respectively. The system runs to the design operating conditions during the start-up process in about 1400 s. In the process of variable operation conditions, the power load in the charge/discharge period can be increased or reduced from the rated value by gas filling or venting, and the system characteristics change accordingly. The simulation model and research findings will offer theoretical insights for optimizing the design of the PTES system.

Modernization of ventilation systems for industrial premises

The article provides a theoretical justification for the possibility of modernizing the ventilation system of a production facility. The relevance of the study is dictated by the need to increase the efficiency of the ventilation system of a production facility through resource conservation and reduction of energy costs. Based on the analysis of the functioning ventilation system, the authors developed an engineering solution consisting of installing functional elements and changing the structure of the system. Modeling of the technical system and its verification were carried out using methods of analysis of linear dynamic systems in the SimInTech software environment. Determining the main parameters for optimizing a technical system and applying stochastic methods to analyze a database of daily temperature values made it possible to form an area of optimal functioning. All studies were carried out on the basis of the Institute of Risk Management and Integrated Safety of the Orenburg State Agrarian University, and the production base for the experimental studies was the research and production enterprise "PnevMax", which is developing a project for modernizing the ventilation system for the production premises of Stroilandiya LLC (Orenburg). Production tests of the modernized ventilation system for the operating premises showed an increase in the efficiency of use of production resources and a significant reduction in energy costs.

Viability of sustainable logistics practices enabling circular economy: A system dynamics approach

AbstractTransitioning toward a circular economy (CE) offers a promising avenue for achieving sustainable logistics systems. Nevertheless, the assessment of sustainable logistics practices (SLPs) in the CE context presents challenges due to the inherent dynamism and complexity of logistics systems. This study aims to assess SLPs toward a CE by employing a system dynamics analysis. Specifically, we focus on four sustainability practices: green purchasing (GP), eco‐design (ED), reverse logistics (RL), and green transportation (GT). These practices are assessed in terms of economic, environmental, and social dimensions of sustainability performance using a hypothetical case study centered on pallet manufacturing and distribution system. The results revealed that the RL practice yields improved economic and social performance, while GT enhances environmental performance more significantly when compared to the other three practices. Our analysis shows RL as a promising practice that enhances overall sustainability performance. This model serves as a valuable tool for decision‐makers aiding them in the prioritization of sustainability practices based on their performance within various CE strategies.

Modeling of forced-vibration systems using continuous-time state-space neural network

Dynamic analysis of forced-vibration systems in civil engineering could be computationally inefficient or even hard to converge if the systems are stiff or highly complicated. Rapid advances in machine learning make it possible to formulate surrogate models for forced-vibration systems using neural networks. The widely used neural networks such as the convolutional neural network (CNN), recurrent neural network (RNN), etc., usually require a constant sampling rate and data length, thus they are difficult to be implemented for real-time calculation of the dynamic system with varying sampling rates. Recently, the continuous-time state-space neural network (CSNN) has shown the capability to lift these restrictions and has been drawing growing attention from the community. In this paper, we propose a generalized CSNN model for various forced-vibration systems (linear and nonlinear). The CSNN model comprises two sets of independent neural networks aiming to compute the state derivative and system response, respectively. Both neural networks adopt linear and nonlinear layers in parallel, instead of only fully connected nonlinear layers as adopted in the literature. This configuration is aimed to enhance the CSNN model with its capability to recognize the linear and nonlinear behaviors of systems. Additionally, the bias options in the CSNN model are all turned off to improve the stability of the model in the long-term time-series forecast, premised on the assumption that the forced-vibration systems are dissipative systems without drift, which is the most common case in civil engineering. Integration on the state derivative at the current time step is executed to obtain the state at the next time step using the explicit 4th-order Runge–Kutta method. Both numerical and experimental illustrative examples are provided, demonstrating that the CSNN model can achieve high performance and training efficiency with a few hyper-parameters, and thus is highly promising for engineering applications.

Extended component mode synthesis method for dynamic analysis of mechanical systems with local nonlinearities

Engineering structures are generally designed based on linear elasticity assumptions. However, it is difficult to describe the connected structures using a simple linear system, due to factors such as sliding and friction at interfaces, and variations in contact areas during vibration processes. Therefore, it is necessary to develop an approach to tackle such systems with interface nonlinearities. In this paper, we proposed an extended free-interface component mode synthesis method. According to the proposed method, the substructures are separated at the nonlinear interfaces. Then the component mode synthesis procedure is carried out. By reasonably neglecting the contributions of higher order modes to the damping and inertia terms, it is demonstrated that the nonlinear interface forces and their time derivatives can be expressed as functions of themselves, as well as modal displacements and velocities. This characteristic facilitates the synthesis of the reduced order models for substructures in the state space. Also owing to this operation, the original properties of nonlinear interface forces can be preserved as much as possible, without any linearization. This method is suitable for non-proportionally damped structures with local nonlinearities such as mechanical structures with nonlinear spring and dashpot connections, rotor-bearing systems and so on. It also may be an alternative for the dynamic analysis of jointed structures with contact nonlinearities. Two numerical examples are presented to demonstrate the capability of the proposed method: (1) an eighteen degrees of freedom spring-dashpot-mass system with cubic spring and cubic dashpot interface connections is studied and (2) a more complex mechanical structure: a dual-rotor system with deep-groove ball bearing inter-shaft support. The numerical simulation results indicate that the dynamic responses of the reduced order model match very well with that of the full model, revealing the high accuracy of the proposed method with low computational costs.

Implementation and Analysis of a Digital Twin for Propylene Glycol Production: Dynamic Simulation and Process Statistical Control

Purpose: Development of a dynamic simulation and analysis system for Propylene Glycol production through the hydrolysis of Propylene Oxide, utilizing market-available tools including a Digital Twin developed in the Unisim/Honeywell Simulation integrated to the PI System AVEVA/OSIsoft. This system aims to provide a realistic industrial environment for subsequent analysis and statical quality control. Theoretical framework: The manufacturing of Propylene Glycol involves complex reactive systems that require precise control and optimization. The integration of advanced simulation tools and statistical control charts, such as Shewhart Control Charts, is pivotal in monitoring and enhancing the quality of the process. This approach addresses the need for efficient process management in the chemical industry. Method/design/approach: The project employs a decoupled simulation structure, where the reactive system and the statistical control system operate simultaneously, exchanging information through the PI System supervisory software (AVEVA/OSIsoft) and a Python programming environment. The implementation of Shewhart Control Charts within the simulation provides real-time process quality monitoring. Results and conclusion: The outcomes demonstrate the feasibility of using a combination of software tools for daily industrial event simulation, as well as for training and acclimatizing engineers and operators. The analysis of statistical control charts allows for the detection of special cause variations, offering valuable insights for efficient process intervention, thereby enhancing the quality of both the process and the final product. Research implications: This study contributes to a deeper understanding of reactive systems in chemical engineering and the effective integration of simulation and statistical process control techniques. Originality/value: The development of a simulation framework that combines Digital Twin technology with statistical process control for the efficient and reliable production of Propylene Glycol.

Cosmological models in [formula omitted] gravity and the dynamical system analysis

The study addresses matter-coupled modified gravity, particularly f(T,T) gravity, unveiling distinct formalism. The research further discusses stability analysis, and the dynamical system approach, exploring the dynamics of critical points to understand these models’ viability better. The dynamical system analysis of the cosmological models in f(T,T) gravity, where T and T respectively represent the torsion scalar and trace of the energy–momentum tensor has been investigated. It demonstrates how first-order autonomous systems can be treated as cosmological equations and analyzed using standard dynamical system theory techniques. Two forms of the function f(T,T) are considered (i) one with the product of trace and higher order torsion scalar and the other (ii) linear combination of linear trace and squared torsion. By employing this methodology, the research aims to uncover the actual behavior of the Universe. The findings emphasize the graphical representation of these insights, enriching our understanding of cosmological scenarios.

Dynamic analysis of a plate system coupled through several nonlinear spring-mass couplers

Nowadays, plates have been widely used in various engineering fields, where nonlinear additional equipment is designed to control the vibration of plates. However, the current studies mainly concentrate on the single-plate system with nonlinear additional equipment. Seldom studies use nonlinear couplers to connect the plate system, making the working mechanism of nonlinear couplers on the vibration responses of the plate system unclear, limiting the application of nonlinear couplers on vibration control of the plate system. To explore the potential application of nonlinear couplers, this work introduces nonlinear spring-mass couplers to connect the plate system, where the transverse vibration analysis model of the plate system coupled through nonlinear couplers is established. The Galerkin truncation method (GTM) is used to predict vibration responses of the plate system coupled through nonlinear couplers. After ensuring the validation of numerical results, forced vibration responses of the plate system coupled by nonlinear couplers are investigated. According to numerical results, responses in the vibration of the plate system are influenced by nonlinear couplers greatly. Choosing suitable parameters for nonlinear couplers plays an important role in the vibration control of the plate system. Under a certain parameter range of nonlinear couplers, responses in vibration present complex characters. Under complex responses, the target energy transfer is present in the vibration responses of the plate system.

Dynamic characteristics analysis of a rotor system with loose support considering internal friction in couplings

Along with the rotating machinery advances toward high speeds, the significance of the excitation force of the seal fluid in the rotor system is growing, which can cause serious accidents. Most of the previous research on rotors in rotating machinery has predominantly focused on the effects of misalignment in couplings. In this article, a novel model is proposed, introducing an analytical approach that combines both internal friction in couplings and loosening support faults. Additionally, an analysis and discussion of the vibration characteristics of the rotating system under the influence of internal friction are presented. This method allows for a more comprehensive assessment of the performance of rotors in engineering applications. Assuming that the left support of the rotor is loose, this model focused on how various factors such as rotor speeds, eccentricity, seal disc mass, and left-end support mass affect the labyrinth seal rotor system's dynamic characteristics. Based on the findings, The emergence of internal friction forces advances the chaos of the rotor. It seems that as the rotating speed increases, there will be a small frequency range, resulting in fluid oscillation, and the system stability will be reduced at this time. The improvement in the seal disc's quality has minimal impact on the stability of the left journal, but it will reduce the stability of the seal disc. The increase in the mass of the left end support will increase the stability of the movement at the left journal and reduce the stability of the movement at the seal disc.

Stroboscopic control and tracking of periodic states

Numerical continuation tools are nowadays standard methods for the bifurcation analysis of dynamical systems. Unfortunately, the full power of these methods is still unavailable in experiments, in particular, if no underlying mathematical model is at hand. We here aim to narrow this gap by providing control based continuation of periodic states which can be ultimately implemented in real-world experimental set-ups. Taking inspiration from atomic force microscopy, we develop experimentally relevant control and tracking tools for time periodic solutions in driven nonlinear oscillator systems based on stroboscopic maps.

Electricity Energy Demand in Banjarnegara District for the Year 2021-2030 Using Linear Regression Method and Leap Software

Electricity demand is expected to increase from year to year. Central Java's electricity demand in 2013 reached 18.205 GWh with a total of 8.092.964 customers. This energy demand has increased in 2018 to 22.945 GWh with a total of 10.011.388 customers. Continuous use of electricity, both directly and indirectly, will also affect economic needs and people's welfare. It is estimated that electricity sales will continue to increase in line with the growth of customers who will also continue to increase. In predicting the need for electrical energy, various forecasting methods are commonly used to predict the need for electrical energy, such as the Regression Method, Time Series Method, Causal Method, Neural Network Method, and Dynamic System Analysis Method. In predicting the need for electrical energy there are advantages and disadvantages of the forecasting method. Based on the availability of data, this research analyzes forecasting the demand for electrical energy in Banjarnegara district using the regression and time series method which is applied using LEAP software. The results show that the total demand for electrical energy using the regression method in 2030 will reach 50.616 GWh while the LEAP software in 2030 will be 59.677 GWh.

A semi-analytical multi-harmonic balance method on full-3D contact model for dynamic analysis of dry friction systems

Dry friction damping structures are widely-used in aero-engines to mitigate vibration. The nonlinear nature of friction and the two-dimensional in-plane motion on the contact interface bring challenges to accurately and efficiently predict the forced response of frictionally damped structures. The state-of-the-art Multi-Harmonic Balance Method (MHBM) on quasi-3D contact model in engineering cannot precisely capture the kinematics on the friction interface although the efficiency is high. The full-3D contact model can describe the constitutive relationship of the interface in a more accurate manner; however, the efficiency and convergence are not guaranteed for large-scale models. In this paper, a semi-analytical MHBM on full-3D contact model is proposed. The original Trajectory Tracking Method (TTM) for evaluating the contact force is reformulated to make the calculation more concise and the derivation of the Analytical Jacobian Matrix (AJM) feasible. Based on the chain rule of derivation, the AJM which is the core to upgrade the performance is deduced. Through a shrouded blade finite element model, the accuracy and efficiency of the proposed method are compared with both the MHBM on full-3D contact model with numerical Jacobian matrix and the MHBM on quasi-3D contact model with AJM. The results show that the AJM improves significantly the efficiency of the MHBM on full-3D contact model. The time cost of the proposed method is in the same order of magnitude as that of the MHBM on quasi-3D contact model. We also confirm that the full-3D contact model is necessary for the dynamic analyses of shrouded blades. If one uses the quasi-3D model, the estimation relative error of damping can even reach 31.8% in some cases. In addition, the AJM also brings benefits for stability analysis. It is highly recommended that engineers use the MHBM on full-3D contact model for the dynamic analysis and design of shrouded blades.

Improved explicit quartic B-spline time integration scheme for dynamic response analysis of viscoelastic systems

A quartic B-spline based explicit scheme is extended for dynamic analysis of viscoelastic systems. In the calculation formulation, different integration approximation schemes for exponential damping models and other damping models are presented. The mathematical derivation of the convolution solving strategy is formulated for viscoelastic systems. For the damping models composed of exponential function, this scheme only requires once convolution calculation in each time step, even though the dynamic equations are used twice. This significantly reduces the calculation time for the damping models composed of exponential function. Numerical examples show that the proposed quartic B-spline based explicit scheme achieves higher accuracy and efficiency compared to other competitive explicit schemes, not only for damping models composed of exponential functions, but also for other viscoelastic damping models.