Doubling Route Research Articles

DT-DDQNR: A digital twin assisted direct-to-cell satellite network intelligent routing algorithm

This paper presents a novel routing algorithm designed for direct-to-cell satellite constellations in satellite networks. The algorithm aims to ensure stable Quality of Service (QoS) for users despite the highly dynamic nature of satellite links and network conditions. It comprises two key components: a terrestrial-satellite link selection model and an inter-satellite multi-hop routing decision model. To enhance decision-making, the algorithm incorporates a mechanism that interacts with large-scale digital twin constellations, offering agents with high-precision state data inputs and feedback for training and application support. The terrestrial-satellite link selection process is modeled as a constraint satisfaction problem, maximizing the Link Quality Indicator (LQI). Meanwhile, inter-satellite data forwarding decisions are determined utilizing an enhanced dynamic reward mechanism and a re-designed neural network in the DDQN model. Simulation results demonstrate the superiority of the Digital Twin-Assisted Double Deep Q-Network Routing (DT-DDQNR) algorithm over traditional routing algorithms in terms of overall network QoS performance, offering a promising solution for optimizing data transmission in integrated terrestrial-satellite networks.

Compatibility of Chrysoperla carnea (Neuroptera: Chrysopidae) with nanoformulations of natural active substances.

Nanoformulations of essential oils (EOs) improve stability of the active ingredient, and thereby its biological activity and persistence. Because compatibility of EOs with natural enemies is not explored sufficiently, we evaluated the impact of nanoformulations of EOs (aniseed, lemon) or pure products (farnesol) on different activities of the generalist predator Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). In dual choice bioassay, chrysopid larvae were significantly attracted to aniseed-treated pepper disks and deterred by farnesol. Larval activities (resting, walking, and preying) on treated leaves infested with Myzus persicae (Sulzer) (Hemiptera: Aphididae) were compared. There were no differences among nanoemulsions, nor aphid consumption varied. We studied the toxicity of nanoformulations to larvae and evaluated their development after contact with treated leaf disks, ingestion of treated artificial diet, and both routes of exposure (application of biopesticides on aphid-infested plants). This is the first evidence of the compatibility of EO nanoformulations with C. carnea by single route of exposure. Whether any effect appeared, it was sublethal. Compounds significantly reduced aphid consumption after 6 h on double route exposure, but this negative short-term effect disappeared as time progressed. Our results showed the optimal biopesticide to apply depends on which biological feature of the natural enemy we targeted. The key element to introduce these nanoemulsions is to match their persistence period on the crop with the release of the appropriate biological stage of C. carnea. This reinforces the fact that the main activities of C. carnea can be substantially maintained in joint application with nanoemulsions of EOs.

Benefit of LDH-Derived Mixed Oxides for the Co-Oxidation of Toluene and CO Exhausted from Biomass Combustion

The proposed study is devoted to highlighting the importance of mixed oxides preparation through the layered double hydroxide route for undesirable gas pollutants abatement. Different series of Cu/Al/Ce mixed oxides with similar or different stoichiometrics were prepared and compared for toluene and/or CO oxidation. Catalyst synthesis methods influence material properties and activity for oxidation reactions. The high activity for the oxidation reactions of mixed oxides derived from LDH is explained by the Cu/Ce synergy. The presence of CO in the CO/toluene mixture does not affect the total toluene oxidation, and the toluene does not affect the total oxidation of CO conversion at low temperatures. The most effective catalytic material (Cu6Al1.2Ce0.8) presents a long lifetime stability for total toluene oxidation and resistance to CO poisoning in mixtures.

Design for all-round PHE/HER/OER sandwich nanostructure catalyst: Ultrathin nanosheet ZnIn2S4-encapsulated rich-Mo edge active site Mo2C-N Schottky junction

The development of efficient multifunctional catalyst remains a huge challenge due to their unsatisfactory oxygen/hydrogen intermediate species adsorption, ineffective kinetics rate, lack of active reaction sites. Herein, rich-Mo edge active sites in the molybdenum carbide (Mo2C) were created through nitrogen doping, which was used as cocatalyst to enhance the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and photocatalytic hydrogen evolution (PHE) of ZnIn2S4 (ZIS). Mo2C-N/ZIS affords a remarkable HER activity with a low overpotential of 74 mV as well as excellent OER activity with a reduced overpotential of 250 mV at 10 mA·cm−2. The formed Schottky junction between Mo2C-N/ZIS are responsible for the enhanced PHE/HER/OER activity, which owns double transfer route beneficial to enhancing separation of photogenerated carriers and reducing bulk/surface recombination of ZIS. Specially, the density functional theory (DFT) calculations demonstrate that Mo2C-N/ZIS Schottky junction with optimal absorption energy for the hydrogen and oxygen intermediates.

Examining the influence of prey dynamics on predator–prey interactions

ABSTRACT We develop variations of a discrete-time predator–prey model to examine how intrinsic properties of the prey population may impact overall system dynamics. We focus on two properties of the prey species, namely developmental stage structure and undercompensatory (contest competition) versus overcompensatory (scramble competition) density dependence. Through analysis of these models, we examine how these different prey features affect system stability. Our results show that when prey growth is overcompensatory, the predator may have a stabilizing effect on the system dynamics with increasing predator density reversing the period doubling route to chaos observed with Ricker-type nonlinearities. Moreover, we find that stage structure in the prey does not have a destabilizing effect on the system dynamics unless the prey projection matrix is imprimitive or close to imprimitive, as may occur for semelparous species. In this case, a sufficiently large predator density may stabilize cycles that are otherwise unstable.

Chaotic mixotroph dynamics arise with nutrient loading: Implications for mixotrophy as a harmful bloom forming mechanism

Mixotrophic nutrition, in which organisms combine aspects of heterotrophic and autotrophic nutrition, is a common characteristic amongst the phytoplankton, and especially amongst harmful algae bloom (HAB) species. To explore how the addition of a mixotrophic population influences a theoretical plankton system under different enrichment levels, we employ a previously published numerical plankton model that reproduces seasonal succession dynamics. Through this work we found potential for chaos to occur as the system was enriched. Focusing on occurrence of chaos in the mixotroph population, a novel finding, we conducted a bifurcation analysis which demonstrated a period doubling route to chaos. Further, we demonstrate that the occurrence of chaotic dynamics in the model system is not an artifact of the mixotroph life-history trait values used in our initial simulations, rather chaos was found to occur under a wide range of mixotroph trait value combinations. Through our trait analysis, we also found that regardless of whether or not the system was chaotic for a specific combination of values, variation in the mixotroph population peak population density could be high between consecutive years. These findings have implications that are important for the management of nutrients in aquatic systems and HABs. Results shed light on why it may be difficult to predict the occurrence of mixotrophic HABs based solely on environmental variables, when the year-to-year peak density of the mixotroph is chaotic or highly variable with enrichment. These results also demonstrate how initiation of a mixotrophic HAB might occur with enrichment, due to erratic population spikes, when broadcast allelopathic or toxic chemicals are at low concentrations, a novel bloom initiation mechanism.

Production of adeno-associated virus in insect cells using multiple gene deleted baculovirus

Adeno-associated virus (AAV) is one of the most frequently used viral vectors in the field of gene therapy. However, the industrial production of AAV is facing key bottlenecks such as low yield and high-cost. The aim of this study was to establish a technology system for production of AAV in the double virus infected insects by using multiple-gene deleted baculovirus. First, a multiple gene deleted baculovirus for AAV production was constructed, and the baculovirus titer and its effect on infected cells was examined. Subsequently, the insect cells were co-infected with the double baculovirus and the infection conditions were optimized. At the final stage, we performed AAV production based on optimized conditions, and evaluated relevant parameters including production titer and quality. The results showed that the titer of AAV produced in the multiple gene deleted baculovirus was not different from that of the wild type, but the rate of cell death was significantly slower upon infection. Using the double virus route for optimized production of AAV, the genome titers were 1.63×1011 VG/mL for Bac4.0-1 and 1.02×1011 VG/mL for Bac5.0-2, which were elevated 240% and 110%, respectively, compared with that of the wild-type. Electron microscopy observations revealed that all three groups exhibited normal AAV viral morphology and they showed similar transduction activity. Taken together, we developed an AAV production system based on the infection of insect cells using multiple-gene deleted baculovirus, which significantly improved the virus yield and showed application potential.

Modeling, analysis and control of parametrically coupled electromechanical oscillators

This work investigates a parametrically coupled electromechanical system of van der Pol and Duffing oscillators. Such a model finds applications in the development of sensors and transducers for the purpose of measurements and actuation. First, the model was developed from the basic components of electrical and mechanical systems, and the governing equations were derived from an energy-based principle. The system was solved analytically by multiple scales method to validate the numerical solutions. Its stability was examined by Floquet theory, and further analysis reveals the presence of Hopf and Neimark–Sacker bifurcations. Other phenomena, such as period doubling and quasiperiodic routes to chaos, were discovered. Additionally, the system exhibits multistability due to the presence of coexisting attractors and synchronization at parametric resonances. Finally, the chaotic system was stabilized by designing a nonlinear feedback controller with time-varying coefficients, bringing its trajectories to the desired equilibrium at the origin for vibration suppression and the desired limit cycle for periodic solutions, respectively. The controlled outputs show a stable invariant closed curve with its Floquet multipliers falling within a unit circle.

Influence of Heat Loss on the Chaotic Dynamics of Reaction Waves in the Model with Chain-Branching Reaction

In this paper, the complex dynamics of the pulsating regime of combustion waves propagation is numerically investigated within the Zel’dovich–Barenblatt–Dold model with two-step chain-branching reaction mechanism. It is shown that there exists a remarkable similarity in the dynamics of oscillations in this system and one-dimensional discrete-time maps such as the logistic map. In particular, both systems exhibit the period doubling route to chaos and the appearance of windows of stability as the bifurcation parameter is increased. For the first time for a model of combustion wave propagation the sequence of windows of stability is demonstrated and classified. Nevertheless, as the activation energy, which is taken as a bifurcation parameter, reaches a critical value corresponding to the dynamical quenching scenario the dynamics of the flame oscillations becomes multidimensional and therefore it cannot be described by a one-dimensional map anymore. The effect of the heat losses is also studied and it is demonstrated that the number of windows of stability decreases, the order of their appearance changes and the dynamical quenching appears for smaller values of the activation energy as the heat losses are increased.

Design and construction of a double Z-scheme CdS@g-C3N4/Bi2MoO6 ternary nanocomposite: Photocatalytic degradation in visible light, adsorption and electrochemical applications

Improved photocatalytic performances can be achieved by synthesizing double heterojunction nanocomposites with suitable conduction band (CB) and valence band (VB) edge potentials. In the current study, a hydrothermal approach was used to successfully synthesize a Z-scheme CdS@g-C3N4/Bi2MoO6 (CdS@GB) ternary nanocomposite with varied CdS contents. The photocatalytic efficiency of the as-synthesized materials was determined by studying the degradation of Rhodamine B (RhB) and Acetaminophen (ACM) pollutants. The experimental results revealed that 15 wt% CdS@GB (15CdS@GB) ternary composite showed the highest photocatalytic performance indicating 98.8 and 83% degradation of RhB and ACM in 35 and 140 min of irradiation, respectively. The stability of the ternary composite was also relatively high even after four consecutive cycles of photodegradation. The main reactive species involved in photodegradation processes was O2•- as revealed by the quenching experiments. The nitro blue tetrazolium (NBT) experiment further confirmed it, which showed the high production of O2•- in the reaction mixture. The synthesized ternary composites were used to study the dark adsorption of RhB, and the results confirmed the applicability of the Langmuir isotherm model. The electrochemical properties of the synthesized materials were investigated using electrochemical impedance spectroscopy (EIS) and cyclovoltammetry (CV). The results showed that 15CdS@GB has the lowest charge-transfer resistance and highest specific capacitance. Based on the findings, a double Z-scheme mechanism route was designed and presented to explain the photodegradation of the target pollutants.

Walking Droplets as a Damped-Driven System

We consider the dynamics of a droplet on a vibrating fluid bath. This hydrodynamic quantum analogue system is shown to elicit the canonical behavior of damped-driven systems, including a period doubling route to chaos. By approximating the system as a compositional map between the gain and loss dynamics, the underlying nonlinear dynamics can be shown to be driven by energy balances in the systems. The gain-loss iterative mapping is similar to a normal form encoding for the pattern forming instabilities generated in such spatially extended systems. Similar to mode-locked lasers and rotating detonation engines, the underlying bifurcations persist for general forms of the loss and gain, both of which admit explicit representations in our approximation. Moreover, the resulting geometrical description of the particle-wave interaction completely characterizes the instabilities observed in experiments.

Double grazing bifurcation route in a quasiperiodically driven piecewise linear oscillator.

Considering a piecewise linear oscillator with quasiperiodic excitation, we uncover the route of double grazing bifurcation of quasiperiodic torus to strange nonchaotic attractors (i.e., SNAs). The maximum displacement for double grazing bifurcation of the quasiperiodic torus can be obtained analytically. After double grazing of quasiperiodic orbits, the smooth quasiperiodic torus wrinkles increasingly with the continuous change of the parameter. Subsequently, the whole quasiperiodic torus loses the smoothness by becoming everywhere non-differentiable, which indicates the birth of SNAs. The Lyapunov exponent is adopted to verify the nonchaotic property of the SNA. The strange property of SNAs can be characterized by the phase sensitivity, the power spectrum, the singular continuous spectrum, and the fractal structure. Our detailed analysis shows that the SNAs induced by double grazing may exist in a short parameter interval between 1 T quasiperiodic orbit and 2 T quasiperiodic orbit or between 1 T quasiperiodic orbit and 4 T quasiperiodic orbit or between 1 T quasiperiodic orbit and chaotic motion. Noteworthy, SNAs may also exist in a large parameter interval after double grazing, which does not lead to any quasiperiodic or chaotic orbits.

INFLUENCE OF DOUBLE CALCINATION-MILLING ROUTE ON THE STRUCTURAL AND MICROSTRUCTURAL PROPERTIES OF LEAD-FREE K0.5NA0.5NBO3 (KNN) CERAMICS

Potassium sodium niobate (KNN) has always been one of the most potential candidates to replace lead-based piezoelectric ceramics due to its strong piezoelectric properties and environmentally friendly composition. A strong piezoelectric property is constantly influenced by the sample's densification as well as its microstructural characteristics. One of the current main issues with this KNN lead-free piezoelectric material is the difficulty in creating high-density samples by conventional preparation and sintering. Thus, KNN lead-free ceramics were synthesised using an improved solid-state method by introducing the double calcination-milling route to this process. The outcome demonstrates that, despite the presence of additional KNN secondary phases, the double calcination-milling approach contributed to the early creation of the KNN phase. When sintered pellets are subjected to a double calcination milling process, the XRD pattern revealed that the main peaks of the sample are indexed to orthorhombic K0.5Na0.5NbO3. The double calcination KNN pellet have a relative density of 90% densification which is slightly higher than that of single calcination KNN pellet which shows 88% densification.

Forward-backward and period doubling bifurcations in a discrete epidemic model with vaccination and limited medical resources.

A discrete epidemic model with vaccination and limited medical resources is proposed to understand its underlying dynamics. The model induces a nonsmooth two dimensional map that exhibits a surprising array of dynamical behavior including the phenomena of the forward-backward bifurcation and period doubling route to chaos with feasible parameters in an invariant region. We demonstrate, among other things, that the model generates the above described phenomena as the transmission rate or the basic reproduction number of the disease gradually increases provided that the immunization rate is low, the vaccine failure rate is high and the medical resources are limited. Finally, the numerical simulations are provided to illustrate our main results.

Generation mechanisms of strange nonchaotic attractors and multistable dynamics in a class of nonlinear economic systems

In this paper, we study strange nonchaotic attractors (SNAs) and multistable dynamics in a class of nonlinear economic systems. For quasiperiodically forced case, the generation and evolution mechanisms of SNAs are discussed. The fractal, Heagy–Hammel, torus doubling, and intermittency routes to SNAs are identified. The Lyapunov exponent, phase-sensitive function and power spectrum are used to characterize the dynamical and geometrical properties of SNAs. Moreover, when multistable phenomenon occur in the system, the boundaries of the basin of attraction may become intertwined, which leads to the economic unpredictability in the long run.

Route to Chaos and Chimera States in a Network of Memristive Hindmarsh-Rose Neurons Model with External Excitation

In this paper we have introduced and investigated the collective behavior of a network of memristive Hindmarsh-Rose (HR) neurons. The proposed model was built considering the memristive autapse of the traditional 2D HR neuron. Using the one-parameter bifurcation diagram and its corresponding maximal Lyapunov exponent graph, we showed that the proposed model was able to exhibit a reverse period doubling route to chaos, phenomenon of interior and exterior crises. Three different configurations of the ring-star network of the memristive HR neuron model, including ring-star, ring, and star, have been considered. The study of those network configurations revealed incoherent, coherent , chimera and cluster state behaviors. Coherent behavior is characterized by synchronization of the neurons of the network, while incoherent behaviors are characterized by the absence of synchronization. Chimera states refer to a differet state where there is a coexistence of synchroniaed and asynchronized nodes of the network. One of the interesting result of the paper is the prevalence of double-well chimera states in both ring and ring-star network and has been first mentioned in the case of memrisitve HR neuron model.

Microcontroller Implementation, Controls, and Synchronization of Three-Dimensional Autonomous System with a Parabolic Equilibrium Point

The microcontroller implementation, controls, and synchronization of a three-dimensional (3D) autonomous system with a parabolic equilibrium point are investigated in this paper. The system in question displays a reverse period doubling route hidden chaotic attractors with two different shapes. Then, the partial and total amplitude controls of the system are achieved by inserting two parameters. A microcontroller implementation is performed in order to confirm the results obtained from the numerical simulations. It is found that the results from the numerical simulations and microcontroller implementation qualitatively agree with each other. The sliding mode controllers are designed to control chaos in the system under study. With the sliding mode control method, the numerical simulations confirm that chaos can be controlled in the 3D autonomous system with a parabolic equilibrium point. In addition, two chaotic 3D autonomous systems with a parabolic equilibrium point and the same parameters are synchronized by the use of a unidirectional linear error feedback coupling scheme. Finally, an active control technique is applied to bring about chaos synchronization between two chaotic 3D autonomous systems with a parabolic equilibrium and different parameters.

Torus doubling route to chaos and chaos eradication in delayed discrete‐time predator–prey models

This paper analyses a class of discrete‐time delayed predator–prey models where time delay is incorporated into the prey's density‐dependent growth term. We explore how time delay, carrying capacity, and harvesting can generate or suppress chaotic motion. Analytical conditions for local stability of the fixed point are derived by using the Routh–Hurwitz criterion. Increasing the time delay has the great potential to change the coexisting stable fixed point to unstable via a Neimark–Sacker bifurcation. Thus, the systems may experience quasi‐periodic and chaotic motion when the coexisting fixed point is unstable. The existence of a quasi‐periodic loop, which generates a 2‐quasi‐periodic loop, and then 4, 8, and 16 quasi‐periodic loops are successively detected as the carrying capacity increases. Further increase of carrying capacity induces chaos. Thus, a torus doubling route to chaos is explored in our article, which has been relatively less reported in the existing literature. Nevertheless, we show that harvesting either prey or predator is more likely to suppress chaos and stabilize the coexisting steady state. We draw all the bifurcation diagrams when delay, carrying capacity, and harvesting strength are varied. The qualitative nature of the phase portraits is determined by computing all the Lyapunov exponents. The analysis of these delayed models in a discrete‐time framework might attract a wide range of researchers to work in this direction. In the conclusion section, we also disclose some remaining questions and future perspectives.

Defect‐Decorated NiFe Bimetallic Nanocatalysts for the Enhanced Hydrodeoxygenation of Guaiacol

AbstractSeries of Ni‐based nanocatalysts were fabricated for the HDO of lignin‐derived guaiacol to cyclohexane via a single‐source Ni−Fe−Al layered double hydroxide precursor route and characterized by XRD, BET, TEM, XAS, XPS, H2‐TPR, H2‐TPD, NH3‐TPD, and pyridine absorbed in situ FT‐IR. As‐fabricated bimetallic NiFe nanocatalyst bearing a Fe/Ni molar ratio of 0.5 : 3 attained a higher cyclohexane yield of 70.5 % under mild reaction conditions (i. e., 230 °C and 1.0 MPa of initial hydrogen pressure), compared to monometallic Ni and other NiFe bimetallic nanocatalysts, as well as monometallic Ni and bimetallic NiFe catalysts prepared by the impregnation method. Combination of experimental results and density functional theory calculations manifested that interfacial FeOx species profoundly facilitated the demethoxylation processes of guaiacol and 2‐methoxycyclohexanol intermediate, while both bimetallic NiFe sites and interfacial FeOx species greatly promoted the dehydroxylation of cyclohexanol intermediate.

DCGCR: Dynamic Clustering Green Communication Routing for Intelligent Transportation Systems

For the effective green communications amongst the vehicles, the energy-efficient routing protocol for intelligent transportation system (ITS) is essential. Due to the high speed and recurring topological variations of Vehicular sensor Networks, identifying a connected route with a sufficient latency is a difficult task with many constraints and obstacles. Therefore, to overcome this, we developed the statistical approach to theoretically determine the load congestion and consumption of energy during the lifetime of the sensor network for ITS. Hence, dynamic clustering green communication routing (DCGCR) protocol is proposed for vehicular communication. To manage energy consumption and enhance the lifetime of the network deployed on the roadside units (RSU), we analyze the evolution of energy holes and apply our analytical conclusions for ITS with WSN routing. The proposed routing protocol considers various metrics: i) energy consumption of vehicular sensor nodes,ii) network stability iii) reliability and iv) amount of data exchange among vehicles. The efficiency of the proposed computational model in calculating the lifetime of the vehicular network and energy hole evolution process is demonstrated through extensive computation results. DCGCR approach is compared with the various energy-aware routing algorithms namely, Dynamic Energy Balanced Routing (DEBR), Geographic Greedy Routing (GGR), double cost function-based routing (DCFR) and found that proposed approach achieves more accuracy with 7% less failure rate.