Slip Problem Research Articles

Research on intelligent optimal allocation control strategy for stability and braking of heavy tyre blowout vehicle

The traditional control strategy mainly compensates and corrects the driving state of heavy vehicles with a tyre blowout, and rarely considers the need for emergency braking. It is also difficult to effectively coordinate the problems of lateral yaw, slip and tailspin, and longitudinal braking performance degradation. For this, an intelligent optimization allocation control strategy combining stability control and braking control is innovatively designed in this article. The joint simulation model for heavy tyre blowout vehicles is built based on the Dugoff tyre blowout model and the TruckSim vehicle model. A linear quadratic form regulator stable control based on the particle swarm optimization algorithm optimization is used to dynamic equilibrium of the additional yaw moment generated by the vehicle tyre blowout. A logic threshold braking control based on adaptive adjustment is adopted to achieve an ideal braking effect for the vehicle. In order to simultaneously consider the stability and braking performance of vehicles with blowout tyre, a braking force distribution strategy and a fuzzy optimization allocation algorithm are proposed to achieve coordination of lateral and longitudinal control strategies. The results indicate that intelligent optimized allocation control can effectively correct the deviation trajectory of a heavy tyre blowout vehicle, enabling it to achieve rapid braking while maintaining stability.

Enhanced Carrier Phase Recovery Using Dual Pilot Tones in Faster-than-Nyquist Optical Transmission Systems

Compared with high spectrum efficiency faster-than-Nyquist (FTN) backbone network, an enhanced carrier phase recovery based on dual pilot tones is more sensitive to capital cost in FTN metropolitan areas as well as inter-datacenter optical networks. The use of distributed feedback (DFB) lasers is a way to effectively reduce the cost. However, under high symbol rate FTN systems, equalization-enhanced phase noise (EEPN) induced by a DFB laser with large linewidth will significantly deteriorate the system performance. What is worse, in FTN systems, tight filtering introduces inter-symbol interference so severe that the carrier phase estimation (CPE) algorithm of the FTN systems is more sensitive to EEPN, thus it will lead to a more serious cycle slip problem. In this paper, an enhanced carrier phase recovery based on dual pilot tones is proposed to mitigate EEPN and suppress cycle slip, in which the chromatic dispersion (CD)-aware Tx and LO laser phase noise is estimated, respectively. Offline experiments results under 40 Gbaud polarization multiplexing (PM) 16-quadrature amplitude modulation (QAM) FTN wavelength division multiplexing (FTN-WDM) systems at 0.9 acceleration factor, 5 MHz laser linewidth, and 500 km transmission demonstrate that the proposed algorithm could bring about 0.65 dB improvement of the required SNR for the normalized generalized mutual information of 0.9 compared with the training sequence-based cycle slip suppression carrier phase estimation (TS-CSS) algorithm.

Longitudinal Shear of a Composite Material in Which the Binder and Inclusions are Weakened by Cohesive Cracks

Background: An elastic medium is considered that is weakened by a doubly periodic system of round holes filled with washers made of a homogeneous elastic material and has cohesive cracks, the surface of which is uniformly covered with a cylindrical non-metallic film. The binder (medium) is weakened by two doubly periodic systems of rectilinear cohesive cracks, directed parallel to the abscissa and ordinate axes, and the length of the crack and their dimensions are not the same (different). General concepts are constructed that describe a class of problems with doubly periodic stress distribution outside circular holes and cohesive cracks under longitudinal shear. The analysis of the limit equilibrium of cracks within the framework of the end zone model is performed on the basis of a nonlocal failure criterion with a force condition for the advancement of the crack tip and a deformation condition for determining the advance of the edge of the end zone of the crack. In solving the problem, the main resolving equations are obtained in the form of infinite algebraic systems and three nonlinear singular integro-differential equations. The equations obtained in each approximation were solved by the Gaussian method with the choice of the main element for different order values depending on the radius of the holes. Calculations were carried out to determine the forces in the connections of the end zones and the ultimate loads causing crack growth. Objective: In the considered problem, the problem of longitudinal slip weakened by cracks parallel to the x axis in the filling medium with two pairs of two periodic cracks weakened by 2 periodic circular holes is considered. In the problem, the boundary problem along the contour of the circular holes is determined, and at the same time, the surface problem is established for the cracks parallel to the x and y axes. The solution of the problem is sought analytically, and taking into account the boundary condition, a system of linear algebraic equations for circular holes and 3 singular integral equations for cracks is obtained. Theoretical Framework: The problem is solved analytically, as the system of linear algebraic equations obtained for circular holes and the system of linear integral equations are jointly solved, and the stress intensity factor at the end of the cracks is determined. Method: The problem was solved using "Kolosova Muskhalashvili" functions and "Collondia's method of solving singular integral equations". Results and Discussion: The main essence of the considered issue is that the stress intensity factor at the end of the cracks is determined according to Fig. 1. Research Implications: For the first time, the stress intensity factor was calculated in composite materials with two pairs of biperiodic cracks of different lengths weakened by biperiodic round holes. Originality/Value: For the first time, the stress intensity coefficient was determined in composite materials with two periodic two pairs of cohesive cracks.

Investigation and Analysis of Influential Parameters in Bottomhole Stick–Slip Calculation during Vertical Drilling Operations

The critical factors that affect bottomhole stick–slip vibrations during vertical drilling operations are thoroughly investigated and analyzed in this research. Influential factors, such as rotation speed, weight on bit (WOB), bottom hole assembly (BHA) configuration, and formation properties, were studied in order to understand their part in the stick–slip phenomena. The analysis is based on a thorough review of previous research conducted on stick–slip drilling vibrations. A mathematical model was created that not only explains axial vibrations but also includes the torsional vibrations present in stick–slip occurrences, which helps with understanding the stick–slip phenomena better. This model can be used as an analytical tool to predict and evaluate the behavior of drilling systems under various operational circumstances. Furthermore, two drilling tests using a WellScan simulator were performed to validate the research findings and assess mitigation techniques’ viability. These test scenarios reflect the stick–slip vibration-producing situations, allowing us to test mitigation strategies. The finding of this study shows the effectiveness of two tactics for reducing stick–slip vibrations. First was the reduction of WOB, which successfully lowered the occurrence of stick–slip vibrations. The second was the increase in the rotation speed, which helped to control the stick–slip problem and increased the drilling speed. This study explains the complex dynamics of stick–slip vibrations during vertical drilling and offers practical, tried-and-true methods for reducing their adverse effects on drilling operations.

Optimization and experimental validation of reinforcing fibers winding pattern for carbon/carbon composite crucible preform

In order to address the problem of transition slip between the cylindrical segment and the ellipsoidal head segment of the carbon/carbon composite crucible preform with asymmetrical structure during the winding process, a winding pattern combining geodesic and non-geodesic is presented innovatively. Firstly, the formulae for the winding angle and the winding central rotation angle of the crucible cylindrical segment and the ellipsoidal head segment are established, and the fourth-order Runge-Kutta numerical method is employed for parametrical design. The two-tangent point winding path is determined by analyzing the effect of the cylindrical segment’s winding pitch, different ellipsoidal head segment heights, and slip coefficient on the winding angle. Secondly, the needle disk winding method is proposed to address the slight winding angle at the open end of the cylinder, making it easier to hang the yarn. Finally, the experiment on dry yarn winding of 3k carbon fiber (linear density: 198 g/km) is carried out. The results indicate that the relative error rate between the actual winding angle and the theoretical design angle differs by no more than 1.66%, demonstrating that carbon fibers can be stably and uniformly wound onto the surface of the carbon/carbon composite crucible preform. Compared to the traditional manual winding method, the winding pattern enhances winding efficiency, ensures carbon fibers’ uniformity and structural stability, and provides a new technological approach to producing high-performance composite materials.

Updated Lagrangian nonlocal general particle dynamics for large deformation problems

The traditional general particle dynamics (GPD) has been successfully applied in modeling fracture propagation, frictional contact and stick–slip problems in rocks. In this study, the updated Lagrangian nonlocal general particle dynamics (UL-NGPD) method is proposed to solve large deformation problems. In the UL-NGPD, the continuity equation and momentum equation are reformulated in the integro-differential formulation by introducing nonlocal theories in the updated Lagrangian framework. The artificial viscosity and artificial force state are utilized to enhance the numerical stability and accuracy in modeling large deformation. The nonlocal velocity gradient in the deformed configuration is used to update the Cauchy stress rate from the Drucker-Prager elasto-plastic constitutive model with strain-softening behaviour for solids. The UL-NGPD paradigm is numerically implemented through an explicit Predictor-Corrector scheme for high-performance computing. The stability and accuracy of the UL-NGPD are verified by numerical tests on compression test, slope stability analysis and aluminum bar collapse experiment. Thereafter, simulations of granular soil collapse and retrogressive landslide in sensitive clays are presented to demonstrate its efficacy and robustness in modeling challenging geotechnical problems involving large deformation. The numerical results show that the proposed UL-NGPD is powerful and suitable for analyzing large deformation problems in geotechnical engineering.

Partially decoupled polarization demultiplexing and phase noise equalizer for Alamouti code-based simplified coherent systems.

Alamouti space-time block code (STBC) combined with a simple heterodyne coherent receiver can realize polarization-insensitive phase-diversity detection to reduce the cost. In the receiver, a joint equalizer has been used for STBC's polarization demultiplexing and phase tracking. However, the joint equalizer requires two different step size parameters to update the tap weight coefficients for polarization demultiplexing and the phase noise estimation. This leads to the search process being complex so requiring more iterations for convergence. In this paper, we propose a partially decoupled equalizer that consists of a polarization and phase decoupled equalizer (PPDE) and a pilot-aided blind phase search (P-BPS) algorithm to accelerate the convergence and improve the phase noise tolerance. By theoretically calculating the phase noise, the PPDE can achieve polarization demultiplexing with only one single step size parameter, thus suppressing the searching space and greatly reducing the iterations required for convergence. In the carrier phase recovery stage, the P-BPS algorithm can effectively improve the phase noise tolerance and solve the cyclic slip problem of BPS. We conduct numerical simulations and an experiment to transmit a quadrature phase-shift keying (QPSK) signal. The results demonstrate that the number of iterations required for PPDE convergence is only half of that of the joint equalizer while maintaining polarization-insensitive characteristics in large phase noise. Meanwhile, the achievable linewidth tolerance of P-BPS is increased by three times compared with DD-LMS.

Advanced winding tension method for preventing axial slip of the center-wound roll

Center winding is one of the most suitable and universal schemes in the winding mechanism. In general, the quality of wound rolls is significantly degraded by axial slip. In this paper, an advanced winding tension method is proposed to overcome axial slip. Firstly, the axial slip mechanism is analyzed by means of the mutual mechanical relationship between the layers of the center-wound roll. Secondly, a mathematical model for overcoming axial slip was developed based on the correlation between axial slip and winding tension. Then, based on the mathematical model, a special neural network structure with back propagation training is developed so that the winding tension is dynamically updated with the winding radius. Finally, a roll-to-roll slitting system for lithium-ion battery pole pieces is proposed and used to verify the performance of the proposed method. The experiments show that there is no quality problem of axial slip in the center-wound rolls wound by the winding tension control method proposed in this paper. It shows that the winding tension control method proposed in this paper is effective in preventing axial slip.

Velocity Slip in a Deep-sea Slurry Pump and Its Effect on Particle Transportation

The slurry pump, which forms the core equipment of the deep-sea mining (DSM) system, provides lifting power for the ore from the seabed to the sea level, which is crucial for the safety of coarse ore particle transportation. Velocity slip plays a significant role in revealing the migration of the pump particles. Therefore, this study analyzes the velocity slip in a slurry pump using the computational fluid dynamics–discrete element method (CFD-DEM) for the first time. The relationship between the pump head and velocity slip was proposed and verified in this study based on the velocity triangle and Euler equation of the solid-liquid two-phase flow in the impeller. The effects of different particle sizes on the velocity slip are compared in detail. According to the computational results, the head depends on the larger velocity slip of the impeller outlet and lower velocity slip at the inlet. The peak value of the velocity slip was significantly reduced, and the peak position of the velocity slip and zero-point position moved backward for particle sizes ranging between 5-15 mm. This study provides a reference for the problems of particle migration and velocity slip in slurry pumps.

Research on weighted carrier phase three difference precision velocity measurement method based on BDS / GPS integrated system

Aiming at the problem of velocity measurement accuracy in single system carrier phase differential velocity measurement and the possible cycle slip in the process, a carrier phase three difference method is proposed to further improve the velocity measurement accuracy. The use of carrier phase triple difference positioning has been very mature, but there is not much research in velocity measurement. Therefore, this paper uses carrier phase triple difference for velocity measurement. At the same time, in order to improve the cycle slip problem in the process, an integral Doppler double difference combined with carrier phase triple difference is proposed, and then a method to improve the cycle slip based on weight is obtained. Both static and dynamic tests show that the carrier phase triple difference method can improve the speed measurement accuracy, and the weighted carrier phase triple difference method can improve the cycle slip.

Induction motors with copper rotor: a new opportunity for increasing motor efficiency

<p>The copper rotor induction motor (CURIM) was recently introduced because it has lower rotor fusion losses than the aluminum rotor (ALRIM). Furthermore, with CURIM, it is easier to reach IE4 and IE5 efficiency levels. The CURIM is advantageous for compact motors, escalators, and electric vehicle applications. However, CURIMs present slip, power factor, temperature increase, and torque decrease problems that must be analyzed. This study compared the economic feasibility of using CURIM with ALRIM by applying discount techniques. A case study was carried out in a sugar company with a cyclical operation, where 5.5 kW motors will be installed in the intermediate conductors of the mill's feeders. The facility works three shifts between 3 and 6 months. The cost increase (DCI) of CURIM over ALRIM was between 1.1 and 1.5 times. With 3,600 h/year and 4,000 h/year of operation, the DCI greater than 10%, it was found that the payback is more than four years, and the net present value (NPV) grows linearly.</p>

Dynamische Modellierung von Schlupf bei Windturbinen Pendelrollen-Hauptlager

This paper considers the problem of the dynamic modelling of macro slip in spherical roller bearings. By revisiting the fundamental physics which drive these systems, potential issues in existing models have been identified. Furthermore, in pure rolling conditions it was found that governing differential equations become “stiff”, requiring the use of implicit methods of time integration. The problem of individual roller macro slip in a wind turbine main bearing is then investigated using a simplified representation of system dynamics. Model results indicate clear links between slip/friction and the operational strategy of the wind turbine, as well as significantly higher frictional effects in the downwind main bearing row. Due to modelling simplifications, these results should not yet be considered conclusive, with further work required.

When is the Porous, Laminar Flow Problem with Slip Condition Well Posed? And Where Does the Solution Lie?

The aim of this article is to advance the current state of knowledge for steady, isothermal, incompressible, laminar flow within a channel featuring a non-zero tangential (or slip) velocity at the permeable walls. There has been significant interest in understanding the solutions to these problems. However, a firm mathematical understanding of the solutions to the slip problem and their properties is yet to be fully developed. For example, we still do not know: if the slip problem is well-posed; where the precise solution lies; if and how approximations converge to the solution; and what the estimates on approximation errors are. Herein we formulate a new mathematical foundation that includes existence; uniqueness; location; approximation; convergence and error estimates. Our strategy involves developing insight via new and interesting connections between the boundary value problem arising from modelling the laminar flow with slip velocity, and the theory of fixed points of operators.

Linking boundary conditions for kinetic and hydrodynamic description of fermion gas

An approximate analytical solution of the boundary slip problem in magnetic field is obtained by using the general form of boundary conditions for the distribution function of fermions with the isotropic energy spectrum. Exact numerical calculations of the slip length for different models of angle-dependent specularity parameter and application of the results to the description of the Poiseuille flow demonstrate the reliability of the approximate solution for establishing a direct link between the hydrodynamic and the kinetic approaches to transport in bounded fermion systems.

Flexural behavior of hybrid FRP-concrete-steel double-skin tubular beams with PBL shear connectors

Hybrid fiber-reinforced polymer (FRP)-concrete-steel double-skin tubular beams (DSTBs) have a very ductile load–deflection response but may experience a relatively large slip between the concrete and the inner steel tube. Perfobond (PBL) shear connectors, which have a perforated steel plate with transverse reinforcing bars passing through the perforations, are widely used to enhance the bond performance between the concrete and the steel section for composite beams. In this study, for the first time, PBLs are employed in hybrid DSTBs to tackle the excessive slip problem. Four-point bending tests are performed on eight hybrid DSTBs with two cross-sectional shapes of inner steel tubes, two types of PBL plates, and four different PBL arrangements. Results identify that a typical load–deflection curve consists of three segments: an initial linear segment up to the yielding of steel tube bottom surface, a hardening segment, and an almost flat load plateau segment. The slips between concrete and steel tubes increase in a faster rate when yielding occurs at steel tube bottom surface. Overall, specimens with PBLs placed along the full span have the smallest slips (around 0.2 mm), whereas maximum slips occur for specimens with foams inserted at the spacings between PBLs (i.e., 2.33 and 0.59 mm for specimens with a circular and a square steel inner tube respectively). PBL shear connectors have efficiently reduced the slip, when comparing with the results of some hybrid DSTBs in previous studies.

A Study on the Detecting Cycle Slips and a Repair Algorithm for B1/B3

For the current problem of cycle slips in the observation data of the BDS-2 and BDS-3 (Bei Dou Navigation Satellite System), in this paper, BDS B1I and B3I signals are used as research objects to study the detection of cycle slips, and their repair algorithm. The Geometry-free (GF) and Melbourne–Wübeena (MW) combination algorithm are used for the detection of cycle slips. A new method of arc partition is proposed in this work to detect cycle slips as the boundary to delimit two different observation arcs. In this way, the different values of cycle slips can be divided and marked. Moreover, the gross errors can be removed. Finally, the detection of cycle slips and the analysis of all epochs can be completed and repaired. This work also analyzes the dual-frequency data effect of cycle slips on code multipath observation. The results showed that this method greatly improved the speed of detection of cycle slips.

The influence of 2D periodic surface texture on the partial slip problem for elastic bodies

We consider contact interaction of elastic bodies, one of which has a 2D texture, described by a sinusoidal function of 2n power, in partial slip conditions within two material models. The first approach based on the Cattaneo-Mindlin theory for linear elastic half-plane, the second is an elastic foundation model (EFM) which takes into account normal and tangential compliances. Analytical expressions for determining the size of the contact zone and the stick and slip zones for both models are obtained, as well as the expressions for the normal and tangential tractions. It is shown that for relatively small profile heights, both models give close results for the stick and slip zones sizes when the parameters of the EFM are selected from the developed half-plane solution. We analyze the influence of the geometric parameters (shape, profile height, and distance between the grooves) of the texture profile on the stick zone size while the tangential force increases. The EFM model allows capturing the dependence of the stick zone width on the profile height.

Dynamic Characteristics and Anti-slip Grasping of Two-Finger Translational Manipulator.

Aiming at the problem of deformation and slip of disc-shaped rubber gasket in the process of grasping, a two-finger translational manipulator based on ABB1410 robot is designed. The kinematics model of the two-finger translational manipulator is established, and the geometric relationship between the motor angle and grasp position is obtained. Based on the two-dimensional force sensor, the dynamic characteristics of the two-finger translational manipulator were studied, and the relationship between the grasping force and the deformation and slip of the disc-shaped rubber gasket was obtained. A prototype of two-finger translational manipulator is developed. The experimental results show that when the grasping force is 5 N, small deformation and stable grasping can be achieved. The grasping and handling process of disk-shaped rubber gasket is designed based on Robot Studio software, and the verification experiments were carried out. The experimental results show that the system can achieve the small deformation and stable grasping of flexible objects, which is consistent with the simulation results. The research can provide theoretical and experimental basis for the design of automation system structure and process control.

Slip Estimation and Compensation Control of Omnidirectional Wheeled Automated Guided Vehicle

To achieve Industry 4.0 solutions for the networking of mechatronic components in production plants, the use of Internet of Things (IoT) technology is the optimal way for goods transportation in the cyber-physical system (CPS). As a result, automated guided vehicles (AGVs) are networked to all other participants in the production system to accept and execute transport jobs. Accurately tracking the planned paths of AGVs is therefore essential. The omnidirectional mobile vehicle has shown its excellent characteristics in crowded environments and narrow aisle spaces. However, the slip problem of the omnidirectional mobile vehicle is more serious than that of the general wheeled mobile vehicle. This paper proposes a slip estimation and compensation control method for an omnidirectional Mecanum-wheeled automated guided vehicle (OMWAGV) and implements a control system. Based on the slip estimation and compensation control of the general wheeled mobile platform, a Microchip dsPIC30F6010A microcontroller-based system uses an MPU-9250 multi-axis accelerometer sensor to derive the longitudinal speed, transverse speed, and steering angle of the omnidirectional wheel platform. These data are then compared with those from the motor encoders. A linear regression with a recursive least squares (RLS) method is utilized to estimate real-time slip ratio variations of four driving wheels and conduct the corresponding compensation and control. As a result, the driving speeds of the four omnidirectional wheels are dynamically adjusted so that the OMWAGV can accurately follow the predetermined motion trajectory. The experimental results of diagonally moving and cross-walking motions without and with slip estimation and compensation control showed that, without calculating the errors occurred during travel, the distances between the original starting position to the stopping position are dramatically reduced from 1.52 m to 0.03 m and from 1.56 m to 0.03 m, respectively. The higher tracking accuracy of the proposed method verifies its effectiveness and validness.

Review of Vehicle Active Safety Systems and Their Coordinated Control

Background:It is obvious that the safety concern associated with a vehicle is greatly valued by all, whether it is now or in the future, the automobile safety issue is the hotspot and the focus of the research by experts and scholars. The continuous increase in car ownership brings convenience to people's life and also poses a threat to people's life and property. Vehicles’ active safety system is the hotspot of current research and development, which plays an important role in automobile safety. Firstly, the vehicle’s active safety technology and its development are introduced. Then, a review is carried out examining the Anti-Lock Brake System (ABS), the Electronic Brake force Distribution (EBD/CBC), the Brake Assist System (BAS/EBA/BA), the Traction Control System (TCS/ASR), the Vehicle Stability Control (VSC/ESP/DSC), etc. At present, there are many patents on the control of each subsystem, but few patents on the integrated control for the active safety of vehicles.Objective:The main contents of this paper are as follows: the control strategies and methods of different active safety systems, the strategies to improve the stability of a vehicle control system and ensure the effectiveness of active safety system control. It provides a reference for the development of active safety control technology and patent.Methods:Through the analysis of different control algorithms and control strategies of Anti-lock and braking force distribution systems, it is pointed out that the switching of EBD/ABS coordinated control strategy according to slip rate can make full use of slip rate and road adhesion coefficient to improve the safety of the system. For the BAS, the slip problem is solved through the combination of the Mechanical Assistant Braking System (MABS) and Electronic Braking Assistant (EBA) system by measuring the distance and the speed of the vehicle ahead. The optimal slip rate control is realized by different control algorithms and control strategies of the traction control system. It is pointed out that the adaptive fuzzy neural controller should be used to control the yaw angular velocity and centroid side angle of the Electronic Stability Program (ESP), which has a good effect on maintaining vehicle stability. A sliding mode variable structure controller combined with constant speed control and law control is used to control the yaw moment.Results:Through the coordinated control strategy of EBD/ABS, the slip rate and road adhesion coefficient were fully utilized by switching according to the slip rate. The problem of the sliding slope was solved by MABS with EBA system. The ESP should use an adaptive fuzzy neural controller to control the yaw angular velocity and centroid side angle, and adopt the joint sliding mode variable structure controller which combines the ABS control and the yaw moment control. Through the optimal control theory, the coordinated control of each subsystem can significantly improve driving stability, riding comfort, fuel economy and so on.Conclusion:This study adopts different control strategies and control algorithms for different active safety control systems and makes full use of the tire-road friction coefficient and slip ratio optimal slip ratio. These focus on accurate control of control variables such as yawing angular velocity, centroid side-slip angle, yawing moment and finally ensure the vehicle braking stability, robustness of the controller and the lateral stability of the vehicle.