Stability and control of the nonlinear system for tractor with N trailer in the presence of slip

In many engineering systems, it is not enough to merge the system paths to zero at infinite time, but the speed of moving these paths to zero is very important. Estimating this speed can be done using exponential functions. This concept is used in exponential stability definition. The purpose of this paper is to design a controller for problem inputs and implement a system of a car with N to a trailer connected to it. This approach is based on the analysis of the Lyapunov stability method. In the given problem, the purpose of conducting and converging the system considering the slip phenomenon as a primitive uncertainty in the system is toward the desired point. Since the trailer tractor system has limitation constraints in the modeling structure, it is difficult to guarantee the stability of a non-holonomic system. Because no controller designed by the control feedback method can continuously and stable ensure the convergence of the system. If this possibility almost dynamic errors, even adaptive controls do not versatile with the operation of the Lyapunov function, especially in the presence of uncertainties, which is a very important factor in system instability, which requires the development of controllers designed to deal with these disturbances. In the simulated results, this paper not only examines the convergence properties, but also shows the ability to control the system by designing a controller in the presence of a slip phenomenon to strengthen the system in the stability debate.

The Pharmacokinetics of Buserelin after Intramuscular Administration in Pigs and Cows

Background: Buserelin is a LHRH agonist used for the treatment of hormone-dependent diseases in males and females. However, the pharmacokinetics of buserelin in pigs and cows are not clearly understood. This study was designed to develop a sensitive method to determine the concentration of buserelin and to investigate the pharmacokinetic parameters after intramuscular (i.m.) administration in pigs and cows. Results: A sensitive and rapid stability method based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed. The pharmacokinetic parameters of buserelin after i.m. administration were studies in five pigs and five cows at a single dose of 1 mg per pig and 3 mg per cow. The plasma kinetics were analyzed by WinNonlin 8.1.0 software using a non-compartmental model. The mean concentration area under the curve (AUC0-t) was 25.02 ± 6.93 h·ng/mL for pigs and 5.63 ±1.86 h·ng/mL for cows. The maximum plasma concentration (Cmax) and time to reach the maximum concentration (tmax) were 10.99 ± 2.04 ng/mL and 0.57 ± 0.18 h for pigs and 2.68 ± 0.36 ng/mL and 1.05 ±0.27 h for cows, respectively. The apparent volume of distribution (Vz) in pigs and cows was 80.49 ± 43.88 L and 839.88 ± 174.77 L, respectively. The elimination half-time (t1/2λz), and clearance (CL) were 1.29 ± 0.40 h and 41.15 ± 11.18 L/h for pigs and 1.13 ± 0.3 h and 545.04 ± 166.40 L/h for cows, respectively. No adverse effects were observed in any of the animals. Conclusion: This study extends previous studies describing the pharmacokinetics of buserelin following i.m. administration in pigs and cows. Further studies investigating other factors were needed to establish therapeutic protocol in pigs and cows and to extrapolate these parameters to others economic animals.

Dynamic Analysis and Hopf Bifurcation of a Lengyel–Epstein System with Two Delays

In this paper, a Lengyel–Epstein model with two delays is proposed and considered. By choosing the different delay as a parameter, the stability and Hopf bifurcation of the system under different situations are investigated in detail by using the linear stability method. Furthermore, the sufficient conditions for the stability of the equilibrium and the Hopf conditions are obtained. In addition, the explicit formula determining the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are obtained with the normal form theory and the center manifold theorem to delay differential equations. Some numerical examples and simulation results are also conducted at the end of this paper to validate the developed theories.

Event-triggered Neural Network-Based Adaptive Control for a Class of Uncertain Nonlinear Systems

In the paper, an event triggering adaptive control method based on neural network (NN) is proposed for a class of uncertain nonlinear systems with external disturbances. In order to reduce the network resource utilization, a novel event-triggered condition by the Lyapunov approach is proposed. In addition, the NN controller and adaptive parameters determined by the Lyapunov stability method are updated only at triggered instants to reduce the amount of calculation. Only one NN is used as the controller in the entire system. The stability analysis results of the closed-loop system are obtained by the Lyapunov approach, which shows that all the signals in the systems with bounded disturbance are semi-globally bounded. Zeno behavior is avoided. Finally, the analytical design is confirmed by the simulation results on a two-link robotic manipulator.

Transfer Learning based Impedance Identification of Voltage Source Converters

The black-box impedance of the voltage source converters (VSCs) can be directly identified at the converter terminal without access to its internal control details, which greatly facilitates the converter-grid interactions. However, since the limited impedance data amount in practical industrial applications, the existing impedance identification methods cannot accurately capture characteristics of the impedance model at various operating scenarios, which is the indicators of the VSCs system stability at the changing profiles of renewables and loads. In this paper, a transfer learning based impedance identification is proposed to fill this research gap. This method can significantly reduce the required data amount used in impedance identification so that the black-box impedance-based stability method could be applied for the practical industrial application. The comparison results confirm the accuracy of the impedance model obtained by this transfer learning based impedance identification method.

Evolution and effectiveness of HPLC Technique for rapid estimation of an Antiallergenic agent Bilastine

A new, simple, accurate, and specific RP-HPLC stability method for determining bilastine was developed and validated. The proposed method was administered using C18 BDS Hypersil thermo column (4.6 × 250mm i.d), 5 µm particle size with a combination of potassium dihydrogen phosphate buffer pH 6.0: acetonitrile: methanol (50:25:25) as the mobile phase at a wavelength of 220nm. The retention time was 3.9 min for bilastine. The calibration plot was linear over the concentration range of 14.4–33.6µg/ml bilastine with LOD and LOQ of 0.04 and 0.11µg/ml, respectively. The technique was validated for linearity, sensitivity, accuracy, precision, and robustness. Percent recoveries were observed to be nearly 100%. The validated method was used for determining bilastine in Pharmabilast(R) tablets. The technique could be appropriate for routine evaluation at laboratories.

Transfer Learning based Impedance Identification of Voltage Source Converters

The black-box impedance of the voltage source converters (VSCs) can be directly identified at the converter terminal without access to its internal control details, which greatly facilitates the converter-grid interactions. However, since the limited impedance data amount in practical industrial applications, the existing impedance identification methods cannot accurately capture characteristics of the impedance model at various operating scenarios, which is the indicators of the VSCs system stability at the changing profiles of renewables and loads. In this paper, a transfer learning based impedance identification is proposed to fill this research gap. This method can significantly reduce the required data amount used in impedance identification so that the black-box impedance-based stability method could be applied for the practical industrial application. The comparison results confirm the accuracy of the impedance model obtained by this transfer learning based impedance identification method.

Fixed-time formation tracking for multiple nonholonomic wheeled mobile robots based on distributed observer

This paper studies the distributed fixed-time formation tracking problem of multiple nonholonomic wheeled mobile robots system over directed fixed and switching topologies. Through a classical nonlinear transformation, the formation control problem is transformed into a consensus problem. New control protocols based on a distributed observer are proposed. The communication topology between multiple nonholonomic wheeled mobile robots is directed, which can reduce the energy loss of communication. Some sufficient conditions of multiple robots achieving the expected formation pattern are given. All follower robots can track the leader's trajectory, form the desired formation shape within a fixed settling time, and make the leader in the geometric center of the formation. By adopting graph theory, Lyapunov stability method and fixed time theory, one can obtain an upper bound of the settling time, and the settling time is independent of the system's initial states. Finally, two examples are presented to illustrate the potential correctness of the main results.

Oil-Based Drilling Fluid Plugging Method for Strengthening Wellbore Stability of Shale Gas

Finding out the reasons for wellbore instability in the Longmaxi Formation and Wufeng Formation and putting forward drilling fluid technical countermeasures to strengthen and stabilize the wellbore are very crucial to horizontal drilling. Based on X-ray diffraction, electron microscope scanning, linear swelling experiment, and hot-rolling dispersion experiment, the physicochemical mechanism of wellbore instability in complex strata was revealed, and thus, the coordinated wellbore stability method can be put forward, which is “strengthening plugging of micropores, inhibiting filtrate invasion, and retarding pressure transmission.” Using a sand bed filtration tester, high-temperature and high-pressure plugging simulation experimental device, and microporous membrane and other experimental devices, the oil-based drilling fluid treatment agent was researched and selected, and a set of an enhanced plugging drilling fluid system suitable for shale gas horizontal well was constructed. Its temperature resistance is 135°C and it has preferable contamination resistibility (10% NaCl, 1% CaCl2, and 8% poor clay). The bearing capacity of a 400 μm fracture is 5 MPa, and the filtration loss of 0.22 μm and 0.45 μm microporous membranes is zero. Compared with previous field drilling fluids, the constructed oil-based drilling fluid system has a greatly improved plugging ability and excellent performance in other aspects.