A nonlinear wake model of a wind turbine considering the yaw wake steering

Duo to fluctuations in atmospheric turbulence and yaw control strategies,wind turbines are often in a yaw state.To predict the far wake velocity field of wind turbines quickly and accurately,a wake velocity model was derived based on the method of momentum conservation considering the wake steering of the wind turbine under yaw conditions.To consider the shear effect of the vertical incoming wind direction,a two-dimensional Gaussian distribution function was introduced to model the velocity loss at different axial positions in the far wake region based on the assumption of nonlinear wake expansion.This work also developed a“prediction-correction”method to solve the wake velocity field,and the accuracy of the model results was verified in wake experiments on the Garrad Hassan wind turbine.Moreover,a 33-kW two-blade horizontal axis wind turbine was simulated using this method,and the results were compared with the classical wake model under the same parameters and the computational fluid dynamics(CFD)simulation results.The results show that the nonlinear wake model well reflected the influence of incoming flow shear and yaw wake steering in the wake velocity field.Finally,computation of the wake flow for the Horns Rev offshore wind farm with 80 wind turbines showed an error within 8%compared to the experimental values.The established wake model is less computationally intensive than other methods,has a faster calculation speed,and can be used for engineering calculations of the wake velocity in the far wakefield of wind turbines.

Ascertaining the influences of auxiliary qubits on the Einstein–Podolsky–Rosen steering and its directions

Einstein–Podolsky–Rosen(EPR) steering is an example of nontrivial quantum nonlocality and characteristic in the non-classical world.The directivity(or asymmetry) is a fascinating trait of EPR steering,and it is different from other quantum nonlocalities.Here,we consider the strategy in which two atoms compose a two-qubit X state,and the two atoms are owned by Alice and Bob,respectively.The atom of Alice suffers from a reservoir,and the atom of Bob couples with a bit flip channel.The influences of auxiliary qubits on EPR steering and its directions are revealed by means of the entropy uncertainty relation.The results indicate that EPR steering declines with growing time t when adding fewer auxiliary qubits.The EPR steering behaves as damped oscillation when introducing more auxiliary qubits in the strong coupling regime.In the weak coupling regime,the EPR steering monotonously decreases as t increases when coupling auxiliary qubits.The increases in auxiliary qubits are responsible for the fact that the steerability from Alice to Bob(or from Bob to Alice) can be more effectively revealed.Notably,the introductions of more auxiliary qubits can change the situation that steerability from Alice to Bob is certain to a situation in which steerability from Bob to Alice is certain.

A 1-bit electronically reconfigurable beam steerable metasurface reflectarray with multiple polarization manipulations

A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180°out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y-or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 d Bi and 17.26 d Bi within the scan range of about ±50°. With the right-handed circular polarization(RHCP) excitation, the left-handed circular polarization(LHCP) radiation with the peak gain of 16.98 d Bic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.

Enhancing quantum temporal steering via frequency modulation

Various strategies have been proposed to harness and protect space-like quantum correlations in different models under decoherence.However,little attention has been given to temporal-like correlations,such as quantum temporal steering(TS),in this context.In this work,we investigate TS in a frequency-modulated two-level system coupled to a zero-temperature reservoir in both the weak and strong coupling regimes.We analyze the impact of various frequency-modulated parameters on the behavior of TS and non-Markovian.The results demonstrate that appropriate frequency-modulated parameters can enhance the TS of the two-level system,regardless of whether the system is experiencing Markovian or non-Markovian dynamics.Furthermore,a suitable ratio between modulation strength and frequency(i.e.,all zeroes of the 0th Bessel function J_(0)(δ/?))can significantly enhance TS in the strong coupling regime.These findings indicate that efficient and effective manipulation of quantum TS can be achieved through a frequency-modulated approach.

Einstein-Podolsky-Rosen Steering and Nonlocality in Open Quantum Systems

We investigate the dynamical behavior of quantum steering (QS), Bell nonlocality, and entanglement in open quantum systems. We focus on a two-qubit system evolving within the framework of Kossakowski-type quantum dynamical semigroups. Our findings reveal that the measures of quantumness for the asymptotic states rely on the primary parameter of the quantum model. Furthermore, control over these measures can be achieved through a careful selection of these parameters. Our analysis encompasses various cases, including Bell states, Werner states, and Horodecki states, demonstrating that the asymptotic states can exhibit steering, entanglement, and Bell nonlocality. Additionally, we find that these three quantum measures of correlations can withstand the influence of the environment, maintaining their properties even over extended periods.

Analysis on steering characteristics of crawler pipeline robot

In order to improve the elbow passing performance and different diameter adaptability of pipeline robot,a supported crawler pipeline robot is designed,which adopts screw nut mechanism and hinge four-bar mechanism to adapt to the complex environment such as variable diameter pipeline and elbow.The steering characteristics passing through the elbow are studied,the kinematic of pipeline robot bending steering is established,the geometric constraint(GC)and steering constraint(SC)in the elbow are analyzed,and the steering experiment is conducted.The results show that the robot can pass through the elbow by the SC model.The SC model can reduce the motor current and energy consumption when the robot passes through the elbow.

Hierarchical CNNPID Based Active Steering Control Method for Intelligent Vehicle Facing Emergency Lane-Changing

To resolve the response delay and overshoot problems of intelligent vehicles facing emergency lane-changing due to proportional-integral-differential(PID)parameter variation,an active steering control method based on Convolutional Neural Network and PID(CNNPID)algorithm is constructed.First,a steering control model based on normal distribution probability function,steady constant radius steering,and instantaneous lane-change-based active for straight and curved roads is established.Second,based on the active steering control model,a three-dimensional constraint-based fifth-order polynomial equation lane-change path is designed to address the stability problem with supersaturation and sideslip due to emergency lane changing.In addition,a hierarchical CNNPID Controller is constructed which includes two layers to avoid collisions facing emergency lane changing,namely,the lane change path tracking PID control layer and the CNN control performance optimization layer.The scaled conjugate gradient backpropagation-based forward propagation control law is designed to optimize the PID control performance based on input parameters,and the elastic backpropagation-based module is adopted for weight correction.Finally,comparison studies and simulation/real vehicle test results are presented to demonstrate the effectiveness,significance,and advantages of the proposed controller.

Visualizing and witnessing first-order coherence,Bell nonlocality and purity by using a quantum steering ellipsoid in the non-inertial frame

A quantum steering ellipsoid(QSE)is a visual characterization for bipartite qubit systems,and it is also a novel avenue for describing and detecting quantum correlations.Herein,by using a QSE,we visualize and witness the first-order coherence(FOC),Bell nonlocality(BN)and purity under non-inertial frames.Also,the collective influences of the depolarizing channel and the non-coherence-generating channel(NCGC)on the FOC,BN and purity are investigated in the QSE formalism.The results reveal that the distance from the center of the QSE to the center of the Bloch sphere visualizes the FOC of a bipartite system,the lengths of the QSE semiaxis visualize the BN,and the QSE's shape and position dominate the purity of the system.One can capture the FOC,BN and purity via the shape and position of the QSE in the non-inertial frame.The depolarizing channel(the NCGC)gives rise to the shrinking and degradation(the periodical oscillation)of the QSE.One can use these traits to visually characterize and detect the FOC,BN and purity under the influence of external noise.Of particular note is that the condition for the QSE to achieve the center of the Bloch sphere cannot be influenced by the depolarizing channel and the NCGC.The characterization shows that the conditions for the disappearance of the FOC are invariant under the additional influences of the depolarizing channel and NCGC.

Controlling stationary one-way steering in a three-level atomic ensemble

We propose a scheme for establishing the stationary one-way quantum steering in a three-level Λ-type atomic ensemble. In our system, the cavity modes are generated from two atomic dipole-allowed transitions, which are in turn driven by two external classical fields. The atomic ensemble can act as an engineered reservoir to put two cavity modes into a squeezed state by two Bogoliubov dissipation pathways. When the damping rates of the two cavity modes are different,the steady-state one-way quantum steering of the intracavity and output fields is presented by adjusting the normalized detuning. The physical mechanism is analyzed based on a dressed state representation and Bogoliubov mode transformation.The achieved optical one-way quantum steering scheme has potential applications in quantum secret information sharing protocols.

Genuine Einstein-Podolsky-Rosen steering of generalized three-qubit states via unsharp measurements

We aim to explore all possible scenarios of(1→2)(where one wing is untrusted and the others two wings are trusted)and(2→1)(where two wings are untrusted,and one wing is trusted)genuine tripartite Einstein-Podolsky-Rosen(EPR)steering.The generalized Greenberger-Horne-Zeilinger(GHZ)state is shared between three spatially separated parties,Alice,Bob and Charlie.In both(1→2)and(2→1),we discuss the untrusted party and trusted party performing a sequence of unsharp measurements,respectively.For each scenario,we deduce an upper bound on the number of sequential observers who can demonstrate genuine EPR steering through the quantum violation of tripartite steering inequality.The results show that the maximum number of observers for the generalized GHZ states can be the same with that of the maximally GHZ state in a certain range of state parameters.Moreover,both the sharpness parameters range and the state parameters range in the scenario of(1→2)steering are larger than those in the scenario of(2→1)steering.

Improved Beam Steering Method Using OAM Waves

Orbital Angular Momentum(OAM)is an intrinsic feature of electromagnetic waves which has recently found many applications in several areas in radio and optics.In this paper,we use OAM wave characteristics to present a simple method for beam steering over both elevation and azimuth planes.The design overcomes some limitations of traditional steering methods,such as limited dynamic range of steering,the design complexity,bulky size of the steering structure,the limited bandwidth of operation,and low gain.Based on OAM wave characteristics,the proposed steering method avoids design complexities by adopting a simple method for generating the OAM-carrying waves.The waves are generated by an array of Planar Circular Dipole(PCD)elements.These elements are designed to cover a wide bandwidth range between 3 and 30 GHz.The transmitting array shows an enhanced gain value from 8.5 dBi to almost 11.5 dBi at the broadside angle.Besides the enhanced PCD-based OAM generation,the novelty of the design lies in a new method of beam steering.Beam steering is then performed by controlling the electrical feeding of the PCD elements;the beam azimuthal location is managed by turning off some of the PCD elements,while the elevation is determined by changing the gradient phase of excitation for the turned-on PCD elements.Detailed analysis of the steering method is carried out by finding the mathematical model of the system and the generated waves.The performance has been verified through numerical simulators.

Cooperative game theory-based steering law design of a CMG system

Spacecraft require a large-angle manoeuvre when performing agile manoeuvring tasks, therefore a control moment gyroscope(CMG) is employed to provide a strong moment.However, the control of the CMG system easily falls into singularity, which renders the actuator unable to output the required moment. To solve the singularity problem of CMGs, the control law design of a CMG system based on a cooperative game is proposed. First, the cooperative game model is constructed according to the quadratic programming problem, and the cooperative strategy is constructed. When the strategy falls into singularity, the weighting coefficient is introduced to carry out the strategy game to achieve the optimal strategy. In theory, it is proven that the cooperative game manipulation law of the CMG system converges, the sum of the CMG frame angular velocities is minimized, the energy consumption is small, and there is no output torque error. Then, the CMG group system is simulated.When the CMG system is near the singular point, it can quickly escape the singularity. When the CMG system falls into the singularity, it can also escape the singularity. Considering the optimization of angular momentum and energy consumption, the feasibility of the CMG system steering law based on a cooperative game is proven.

Impact of Chromium Propionate Supplementation and Days of Adaptation on Energy Status in Newly Weaned Steer Calves*

The objective of this research was to evaluate the influences that supplemental dietary chromium propionate (CrP;0 or 0.4 mg·kg-1 added to the total diet on a DM basis) has on plasma indicators of energy status in newly weaned steers upon introduction to the feedlot. For this experiment single source, Angus steers (n = 28;BW = 289 ± 12.0 kg) from a ranch in Western South Dakota were weaned and immediately shipped 579 km to the Ruminant Nutrition Center (RNC) in Brookings, SD. Steers were allotted to one of four 7.6 m × 7.6 m pens (2 pens/diet;7 steers/pen) at 4 d post-arrival to the RNC and test diets were initiated. No anabolic implant was used in this study. Subsequent BW measurements were obtained at 1400 h, to accommodate a post-prandial timing for blood sampling. This was 4 h after initial access to feed, and immediately prior to the afternoon feed delivery. Weights and blood sampling occurred on d 5, 12, 19, and 33. Whole blood samples were collected from all steers via jugular venipuncture and separated as plasma. There were no diet x day interactions (P ≥ 0.51) for plasma glucose, insulin, or urea-N. Plasma glucose, insulin, and urea-n levels were similar between diets (P ≥ 0.35). Plasma glucose and urea-n levels were not different across days (P ≥ 0.59). Insulin levels differed as a result of days of adaptation and were greatest (P = 0.01) on d 12 regardless of diet. There tended (P = 0.12) to be a diet x day interaction for NEFA levels. Plasma NEFA levels tended to be lower (P = 0.13) for calves fed CrP on d 5, and were greater (P = 0.09) on d 12 in calves fed CrP. The shift in NEFA on d 12 coincided with the spike in insulin levels. Both events occurred at the time that NEg intake was approaching the acclimated plateau and neither event impacted glucose status. In non-ruminants, elevated insulin concentrations decrease circulating NEFA levels. We detected minimal differences in regard to plasma indicators of lipid metabolism in this study due to chromium supplementation. These data indicate that ruminants may differ from non-ruminants in the regulation and maintenance of glucose status and body fat catabolism during the post-absorptive state.

Model development and parameter investigation of a column-type electric power steering system

In this paper, the performance of a column-type electric power steering （EPS） system and vehicle has been studied and a detailed mathematical model for the system has been established. Based on the mathematic model of the optimization design for steering feel, the parameters of the EPS system and vehicle on steering performance have been investigated. Moreover, the effects of the parameters on system stability have been analyzed and compared by the method of absolute sensitivity and the results are given in the end.

Research on Steering Resistance Moment of Wheel Loader

The wheel loader as the research object in present article,its steering mechanism is analyzed for the relationship between the steering cylinder displacement and the steering angle,which means,the relationship between the arm of steering resistance moment and the steering angle.In addition,the relationship between the in-situ steering resistance moment and the wheel angle is also be analyzed by integrating the interaction between the tire and the ground.The Matlab will help to build the mathematical modeling for verification.

Research on Vehicle Control Technology Using Four-Wheel Independent Steering System

The enhancement of vehicle handling stability and maneuverability through active and independent rear wheels control is presented. Firstly, the configuration of four-wheel independent steering prototype vehide is introduced briefly. Then the concrete overall design of the electronic controllers of four wheel independent steering system （4WIS） is formulated in details. Under the control strategy of zero sideslip angle at mass center, the mathematical model of 4WIS is established to deduce the equations of separated rear wheel steering angles. According to these equations, simulation analysis for 4WIS vehicle performances is finished to show that 4WIS vehicle can improve the maneuverability greatly at low speed and increase the handling stability at high speed. Finally, the road test of 4WIS vehide has performed to verify the correctness of simulation and show that compared with the conventional four wheel steering （4WS） vehicle, the 4WIS vehicle not only improves the kinematical harmony but also decreases steering resistance and lighten abrasion of tires.

Mechanical-Hydraulic Co-Simulation of Full Hydraulic Articulated Steering System

With the development and improvement of the hydraulic steering system,the articulated steering system became the research focus of numerous domestic and foreign scholars.The full hydraulic steering system with a compact structure and ease of operation,is widely used in articulated steering mode.Furthermore,its performance can directly impact the steering sensitivity and stability.This paper studies the working principle and actual structure of the priority valve and the steering control valve,which are very important.By setting up a mathematic model,the system’s load-sensing characteristics and the impact of steering control valve bypass throttle damping on steering stability can be analyzed.The Hydraulic Components Design(HCD)model was established for the hydraulic part of this system.It is proved that the model can reflect the system’s actual properties by comparing simulation and experimental results.The dynamic model is based on its actual prototype parameters by taking the tire and ground forces into account.The steering process’s dynamic characteristics are co-simulated in the 1D+3D system model by combining AMESim and Virtual.Lab Motion.The simulation results show that the system’s load-sensing characteristics ensure the sensitivity of the steering operation,and the bypass throttle damping has significantly improved the operation stability and lowered down the cylinder pressure fluctuations.This can improve the system performance by appropriate optimization.

CG STEER旋转导向在长庆页岩油H100平台的应用

随着勘探开发的进一步发展,井数越来越多的大井丛平台已经成为页岩油开发的新模式,给钻井施工及后续作业提出了较高的要求与挑战。特别是在钻井施工中,大偏移距、长裸眼段、长水平段、高摩阻高扭矩等一系列问题,是钻井施工必须面对、且需要立即解决的技术问题,尤其是平台边缘井更为突出。文章根据旋转导向工具特点及平台地质条件、地质靶体要求,优化了井身剖面,优选了配套钻具组合、钻头、钻井液及钻井参数等,并在H100平台得到了成功应用,形成了一套页岩油大井丛平台集“剖面+工艺+工具+钻井液”于一体的旋转导向工具工艺技术,成功解决大偏移距井钻井过程中长裸眼段存在的高摩阻高扭矩等问题,为后期大井丛平台式开发提供技术支撑。

Tracking Performance of Electric Power Steering System Based on the Mixed H_2/H_∞ Strategy

The tracking performance of motor current is an important factor that affects the assistance torque of electric power steering （EPS） system. Bad tracking performance will cause assistant torque delay, and make road feeling bad, and is influenced by the input steering torque and system measuring noise. However the existing methods have some shortages on system＇s robust dynamic performance and robust stability. The mixed H2/H∞ strategy for recirculating ball-type EPS system in a pure electric bus is proposed, and vehicle dynamic model of the system is established. Due to the existence of system model uncertainty, disturbance signals, sensor noises and the demand of system dynamic performance, the indexes of robust performance and road feeling for drivers are defined as the appraisal control objectives. The H∞ method is introduced to design the H∞ controller, and the H2 method is applied to optimize the H∞ controller, thus the mixed H2/H∞ controller is designed. The response of EPS system to the motor current command with amplitude of 20 A, the road disturbance with amplitude of 500 N and the sensor random noise with the amplitude of 1 A is simulated. The simulation results show that the recirculating ball-type EPS system with the mixed H2/H∞ controller can attenuate the random noises and disturbances and track the boost curve well, so the mixed H2/H∞ controller can improve the system＇s robust performance and dynamic performance. For the purpose of verifying the performance of the designed control strategy, the motor current tracking performance ground tests are conducted with step response input of the steering wheel, double-lane steering test and lemniscate steering test, respectively. The tests show that the mixed H2/H∞ controller for the recirculating ball-type EPS system of pure electric bus is feasible. The designed controller can solve the robust performance and robust stability of the system, thus improve the tracking performance of the EPS system and provide satisfied road feeling for the drivers.

Error analysis and a new steering law design for spacecraft control system using SGCMGs

Based on the singular value decomposition theory,this paper analyzed the mechanism of escaping/avoiding singularity using generalized and weighted singularity-robust steering laws for a spacecraft that uses single gimbal control moment gyros （SGCMGs） as the actuator for the attitude control system.The expression of output-torque error is given at the point of singularity,proving the incompatible relationship between the gimbal rate and the output-torque error.The method of establishing a balance between the gimbal rate and the output-torque error is discussed,and a new steering law is designed.Simulation results show that the proposed steering law can effectively drive SGCMGs to escape away from singularities.