Chaos control of a multi-dimensional chaotic mapping system by modified stability transformation method

For the multi-dimensional chaotic mapping system with various forms of bifurcations, it is found that the spectral radius around the static bifurcation point is approximately equal to one and the convergence speed for traditional stability transformation method (STM) which is used to stabilize the unstable fixed points is fairly slow. In this paper, a modified STM is proposed to efficiently stabilize a 3D chaotic mapping system to stable fixed points. Firstly, according to the information of the fixed point, the stability matrix C is derived, demonstrating that it is unnecessarily an involutory matrix for STM that can also stabilize chaotic system to the fixed point. Then, the critical parameter qcrit that satisfies convergence condition and the optimal parameter qopt corresponding to best performance for STM are determined respectively. Moreover, STM is combined with Newton method (NT) to overcome the disadvantage of slow convergence around the static bifurcation point without requiring a priori information of fixed point. It is indicated that the number of iterations, the absolute and relative errors between the convergent value and analytical fixed point for combined STM-NT decrease enormously comparing with that of traditional STM. Finally, numerical analysis verifies the high efficiency of modified STM proposed in this paper

Chaos control of a multi-dimensional chaotic mapping system by modified stability transformation method

For the multi-dimensional chaotic mapping system with various forms of bifurcations, it is found that the spectral radius around the static bifurcation point is approximately equal to one and the convergence speed for traditional stability transformation method (STM) which is used to stabilize the unstable fixed points is fairly slow. In this paper, a modified STM is proposed to efficiently stabilize a 3D chaotic mapping system to stable fixed points. Firstly, according to the information of the fixed point, the stability matrix C is derived, demonstrating that it is unnecessarily an involutory matrix for STM that can also stabilize chaotic system to the fixed point. Then, the critical parameter qcrit that satisfies convergence condition and the optimal parameter qopt corresponding to best performance for STM are determined respectively. Moreover, STM is combined with Newton method (NT) to overcome the disadvantage of slow convergence around the static bifurcation point without requiring a priori information of fixed point. It is indicated that the number of iterations, the absolute and relative errors between the convergent value and analytical fixed point for combined STM-NT decrease enormously comparing with that of traditional STM. Finally, numerical analysis verifies the high efficiency of modified STM proposed in this paper

Vomiting and wasting disease associated with hemagglutinating encephalomyelitis viruses infection in piglets in jilin, china

One coronavirus strain was isolated from brain tissues of ten piglets with evident clinical manifestations of vomiting, diarrhea and dyskinesia in Jilin province in China. Antigenic and genomic characterizations of the virus (isolate PHEV-JLsp09) were based on multiplex PCR and negative staining electron microscopy and sequence analysis of the Hemagglutinin-esterase (HE) gene. These piglets were diagnosed with Porcine hemagglutinating encephalomyelitis virus (PHEV)

Control and Stability Analysis of Double Time-Delay Active Suspension Based on Particle Swarm Optimization

With the application of an active control unit in the suspension system, the phenomenon of time delay has become an important factor in the control system. Aiming at the application of time-delay feedback control in vehicle active suspension systems, this paper has researched the dynamic behavior of semivehicle four-degree-of-freedom structure including an active suspension with double time-delay feedback control, focusing on analyzing the vibration response and stability of the main vibration system of the structure. The optimal objective function is established according to the amplitude-frequency characteristics of the system, and the optimal time-delay control parameters are obtained by using the particle swarm optimization algorithm. The stability for active suspension with double time-delay feedback control by frequency-domain scanning method is analyzed, and the simulation model of active suspension with double time delay based on feedback control is finally established. The simulation results show that the active suspension with double time-delay feedback control could reduce the body’s vertical vibration acceleration, pitch acceleration, and other indicators significantly, whether under harmonic excitation or random excitation. So, it is indicating that the active suspension with double time-delay feedback control has a better control effect in improving the ride comfort of the car, and it has important reference value for further research on suspension performance optimization

Time-Delay Vibration Reduction Control of 3-DOF Vehicle Model with Vehicle Seat

Vehicles driving on the road continuously suffer low-frequency and high-intensity road excitation, which can cause the occupant feelings of tension and dizziness. To solve this problem, a three-degree-of-freedom vehicle suspension system model including vehicle seat is established and a linear function equivalent excitation method is proposed. The optimization of the random excitation is transformed into the optimization of constant force in a discrete time interval, which introduces the adaptive weighted particle swarm optimization algorithm to optimize the delay and feedback gain parameters in the feedback control of time delay. In this paper, the stability switching theory is used for the first time to analyze the stability interval of 3-DOF time-delay controlled active suspension, which ensures the stability of the control system. The numerical simulation results show that the algorithm can reduce vertical passenger acceleration and vehicle acceleration, respectively, by 13.63% and 28.38% on average, and 29.99% and 47.23% on random excitation, compared with active suspension and passive suspension based on inverse control. The effectiveness of the method to suppress road random interference is verified, which provides a theoretical reference for further study of suspension performance optimization with time-delay control

The Study on Vibration Reduction of Nonlinear Time-Delay Dynamic Absorber under External Excitation

The nonlinear time-delay dynamic absorber has a good control effect on the main system under harmonic excitation, but the control effect on the main system under complicated excitation is not obvious. In the previous study, they do not have an effective method to obtain the time-delay control parameters under different external excitations. Because of the above problems, this paper proposed an innovative method to obtain the control parameters of time-delay dynamic absorbers. For the vibration system including the nonlinear time-delay dynamic absorber, the transient time-integration method was used to solve the nonlinear delay dynamic differential equation of the system under the specific excitation. Then, the quantitative relationship was established between the time-domain responses of the vibration system, the external excitation, and time-delay control parameters. The time-delay control parameters would be obtained when the time-domain response of the main system is minimized under specific excitation using an algorithm that continuously compares the objective function that is related to the time-domain response of the main system. This paper took the two-degree-of-freedom vibration system with a nonlinear time-delay dynamic absorber as the target system to simulate the time-domain response of the main system. The simulation results show that the time-delay control parameters calculated by the new method can obtain significant vibration reduction effects for both harmonic excitation and multiharmonic excitation. The suppression performance of the nonlinear time-delay dynamic absorber is significantly improved

Study on the Multi-Mode Optimal Control of Four-Wheel Steering Vehicle

To improve the overall performance of four-wheel steering vehicles under different working conditions and solve the problem of the unbalanced comprehensive control effect of a single controller, a multi-mode optimal decision control system is proposed based on the linear 2-DOF dynamic model of the vehicle, which can make the vehicle have better performance under different working conditions. The system is composed of multiple controllers, in which the self-tuning dual yaw rate feedback controller can create timely feedback and make adjustments according to the driving state of the vehicle, which is optimal under the condition of a small rotation angle at medium and high speeds. The system can match the corresponding controller according to the optimal performance of different control strategies at different speeds and angles. The simulation results show that the multi-mode optimal selection system can make the vehicle perform optimally under different working conditions, and that comprehensive performance is more prominent than that of a single controller

Time- and dose-dependent detoxification and reproductive endocrine disruption induced by tetrabromobisphenol A (TBBPA) in mussel Mytilus galloprovincialis

As a typical brominated flame retardant (BFR), tetrabromobisphenol A (TBBPA) has been frequently detected in both biotic and abiotic matrices in marine environment. Our previous study found that genes related to metabolism phase I/II/III as well as steroid metabolism in Mytilus galloprovincialis were significantly altered by TBBPA treatment. However, the time- and dose-dependent response profiles of these genes to TBBPA exposure were rarely reported. In this study, the time- and dose-dependent effects of TBBPA on detoxification and reproductive endocrine disruption in M. galloprovincialis were explored by evaluating the responses of related gene expressions, enzymatic activities and gametogenesis to different concentrations of TBBPA (0.6, 3, 15, 75 and 375 mu g/L) for different durations (14, 21 and 28 days). The results showed that the TBBPA accumulation increased linearly with the increases of exposure time and dose. Cytochrome P450 family 3 (CYP3A1-like) cooperated with CYP4Y1 for phase I biotransformation of TBBPA in mussels. The dose-response curves of phase II/III genes (glutathione-Stransferase (GST), P-glycoprotein (ABCB), and multidrug resistance protein (ABCC)) showed similar response profiles to TBBPA exposure. The common induction of phase I/II/III (CYPs, GST, ABCB and ABCC) suggested TBBPA detoxification regulation in mussels probably occurred in a step-wise manner. Concurrently, direct sulfation mediated by sulfotransferases (SULTs) on TBBPA was also the vital metabolic mechanism for TBBPA detoxification, which was supported by the coincidence between up-regulation of SULT1B1 and TBBPA accumulation. The significant promotion of steroid sulfatase (STS) might result from TBBPA-sulfate catalyzed by SULT1B1 due to its chemical similarity to estrone-sulfate. Furthermore, the promotion of gametogenesis was consistent with the induction of STS, suggesting that STS might interrupt steroids hydrolysis process and was responsible for reproductive endocrine disruption in M. galloprovincialis. This study provides a better understanding of the detoxification and endocrine-disrupting mechanisms of TBBPA

A review of potential factors promoting fish movement in inter-basin water transfers, with emergent patterns from a trait-based risk analysis for a large-scale project in china

Inter-basin water transfers create new pathways between previously disjunct systems and communities. If fish movement occurs, it can lead to invasion or altered regional connectivity patterns, which could induce biotic/genetic homogenisation or synchronisation. Understanding ecological factors promoting movement is critical for predicting potential impacts during project planning, to assess ongoing effects, and to develop mediation strategies. Potential characteristics influencing movement rates were reviewed, including intrinsic traits that increase passive entrainment or active dispersal rates, extrinsic traits of the connected environments and their interactions. In order to examine patterns among these potentially influencing characteristics, a trait-based screening method for movement and invasion risk was developed to analyse linked communities in a database from a large-scale inter-basin water diversion in China. Groups of fishes that scored high in the risk assessment were compared with worldwide examples of entrainment in inter-basin water transfer systems or smaller-scale diversions to examine emergent patterns of shared ecological characteristics. Specific traits that were most often shared in these groups, indicating a higher likelihood of movement in water diversions, include the following: a smaller body size, high adult or larval abundance, migratory behaviour, generalist and pelagic habitat preferences, and a high reproductive output. The synthesis of factors identified in this research can be used to guide future empirical studies to fill knowledge gaps regarding ecological impacts of inter-basin water transfers or other smaller-scale diversions on local communities and ecosystems

UPLC-MS/MS Method for Simultaneous Determination of Three Major Metabolites of Mequindox in Holothurian

This study developed an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of three major metabolites of mequindox, including 3-methyl-quinoxaline-2-carboxylic acid, 1-desoxymequindox, and 1,4-bisdesoxymequindox (MQCA, 1-DMEQ, and BDMEQ), in holothurian. Target analytes were simplified with ultrasound-assisted acidolysis extracted without complicated enzymolysis steps. After that, each sample was centrifuged and purified by an Oasis MAX cartridge. Then, the processed samples were separated and monitored by UPLC-MS/MS. This developed method has been validated according to FDA criteria. At fortified levels of 2, 10, and 20 μg/kg, recoveries ranged from 82.5% to 93.5% with the intraday RSD less than 7.27% and interday RSD less than 11.8%. The limit of detection (LOD) of all the three metabolites ranged from 0.21 to 0.48 μg/kg, while the limit of quantification (LOQ) ranged from 0.79 to 1.59 μg/kg. On application to commercial samples, 14 of 20 samples were detected positive for the three target analytes, with positive rate at 70 percentage. The result indicated that this method was specific, sensitive, and suitable for the quantification and conformation of the three major metabolites of MEQ in holothurian