Process Of Steering Research Articles

Liquid crystal spatial light modulator based non-mechanical beam steering system fractional-order model.

The liquid crystal spatial light modulator (LCSLM) is an optical device that can realise non-mechanical beam scanning. However, the traditional integer-order model cannot adequately characterise the dynamic performance of LCSLM beam steering because of the viscoelasticity of liquid crystals. This paper uses the memory characteristics of fractional calculus to construct a fractional constitutive equation for liquid crystals. Combining this equation with the LCSLM beam steering principle, a fractional-order model of the beam steering system is established, and the Legendre wavelet integration operational matrix method is used to estimate the model parameters. In addition, we established a test platform for the dynamic characteristics of LCSLM beam steering system and verified the effectiveness of the established model through experiments. The fitting effects of the integer-order and fractional-order models are compared, and the influence of different model orders on the dynamic performance of beam steering is analysed. Experimental results show that the fractional-order model can accurately describe the dynamic process of beam steering, and this model can be applied to the study of LCSLM-based two-dimensional non-mechanical beam steering control strategies to achieve fast, accurate, and stable beam scanning.

Implementation of optimal automatic steering of atomic clock timescale

The problem of physical implementation of atomic timescales maximally adjusted to the national timescale UTC(SU) for working and secondary standards is considered. Results of analysis of stationary process of hydrogen maser timescale automatic steering to UTC(SU) using common view technique based on the signals of global navigational systems are presented. Calculation of Kalman filter and linear quadratic regulator parameters is described. Theoretical and experimental estimations of automatic steering quality characteristics are compared and discussed. The results obtained can be used to improve the accuracy of timescales on working and secondary standards.

Software tool development for estimating forces acting on a formula student racing vehicle using simple vehicle dynamics models

This work focuses on developing a software tool that could predict forces acting on a racing vehicle used for formula student competition with reasonable accuracy to aid the design process of suspension, steering and braking systems in the initial stages of design with a user-friendly interface and utilizing free body diagram based approach and three-dimensional vectors to estimate forces on suspension linkages.

Maatwerk in contact: vragen om verschillen bij complexe opgaven

Governance is a human activity and is therefore unquestionably about relationships. Relationships between public and private parties. Relationships in existing steering-oriented structures (the political administrator as guardian, magistrate) and also relationships in new forms of cooperation that are often focused on good relationships (government participation). Public-private partnerships are inevitably accompanied by conflicting interests that place different demands on interactions. One-size-fits-all does not fit there, but customization is required, with constant alignment with what is – and what is not (yet). And so the ability to make contact requires much more attention, and from there to explore and grasp perspectives. How do you work on the tensions that you find on your way? It is there that the method of communication influences how the process of cooperation and steering proceeds. This is not a matter of whether-or, but and-and. Both perspectives are characterized by a different relationship with those involved and a different way of contact and interaction. This article focuses on contact from a collaborative perspective. The classical administrative side already has a rich history, while the cooperation side is often still an unknown and unexplored territory. The central question is: how can you, as a director and public professional, deliver tailor-made solutions and therefore adapt to complex tasks? The authors look at complex situations from a communicative perspective and they introduce ‘appreciative communication’ as the art of aligning with what really moves people, as a frame of view of the inconvenience caused by the differences present. They highlight a number of generic tensions that can arise in cooperation situations. A case study into the approach to regional innovation in the field of mobility serves as an illustration.

Annual Review of R&D Steering Committee Activities in Power and Energy Society

The R&D Steering Committee is working in planning and Steering of the Research and development of Power and Energy Society. In this article, activities of the committee of the last term are reported, and recent trend and future problems are also discussed. The process of planning and steering of the research and development, and the challenges to activation of Power and Energy Society are shown.

A proposed method for linear accelerator photon beam steering using EPID.

Beam steering is the process of calibrating the angle and translational position with which a linear accelerator's (linac's) electron beam strikes the x‐ray target with respect to the collimator rotation axis. The shape of the dose profile is highly dependent on accurate beam steering and is essential for ensuring correct delivery of the radiotherapy treatment plan. Traditional methods of beam steering utilize a scanning water tank phantom that makes the process user‐dependent. This study is the first to provide a methodology for both beam angle steering and beam translational position steering based on EPID imaging of the beam and does not require a phantom. Both the EPID‐based beam angle steering and beam translational steering methods described have been validated against IC Profiler measurement. Wide field symmetry agreement was found between the EPID and IC Profiler to within 0.06 ± 0.14% (1 SD) and 0.32 ± 0.11% (1 SD) for flattened and flattening‐filter‐free (FFF) beams, respectively. For a 1.1% change in symmetry measured by IC Profiler the EPID method agreed to within 0.23%. For beam translational position steering, the EPID method agreed with IC Profiler method to within 0.03 ± 0.05 mm (1 SD) at isocenter. The EPID‐based methods presented are quick to perform, simple, accurate and could easily be integrated with the linac, potentially via the MPC application. The methods have the potential to remove user variability and to standardize the process of beam steering throughout the radiotherapy community.

System Identification and Steering Control Characteristic of Rice Combine Harvester Model

This study is a preliminary research of rice combine harvester trajectory. A vehicle model of rice combine used crawler with differential steering. Turning process of differential steering used speed difference of right and left tracks This study aims to learn of rice combine harvester steering control. In real condition, the hydraulic break on each track produced the speed difference. The model used two DC motors with maximum speed 100 rpm for each tracks. A rotary encoder with resolution 600 pulse/rotation was connected to each DC motors shaft to monitor the speed of tracks and connected to the input shaft of a gearbox with ratio 1:46. The motor speed control for each track used pulse width modulation to produce the speed difference. A gyroscope sensor with resolution 0.01° was used to determine the model orientation angle. Like the real rice combine, the tracks can not rotate to the opposite direction at the same time so it makes the model can not perform the pivot turn. The turn radius of the model was 28 cm and the forward maximum speed was 17.8 cm/s. The model trajectory control used PID odometry controller. Parameters input were the speed of each track and the orientation of the vehicle. The straight line test showed the controller can control the rice combine model trajectory with the average error 0.67 cm.

Theoretical analysis on power stability and switch time of the non-mechanical beam steering using liquid crystal optical phased array

ABSTRACTFocusing on the coherent optics of phased array, a dynamic theoretical model is built to analyse the process of laser beam steering using the device of liquid crystal optical phased array. Based on the dynamics of electrical field induced liquid crystal molecule rotation and the mechanism of phased control non-mechanical steering, switching time is redefined according to two curves representing receiving power on the current direction and targeting direction. Meanwhile, including the far field distribution, power stability and pointing direction, two cases with large steering step and tiny steering step are evaluated. The steering time between two angles is minished to be less than the switch-off decay time. In addition, the instability on the process of beam steering is obvious although the steering step is only half of beam width. To overcome this instability, tinier steering step is suggested although it is also limited by the driving algorithm and driving circuits.

An integrated mechanical/control design approach to optimisation of an electric power steering system under objective evaluation of vehicle handling and stability

In the R&D process of electric power steering (EPS) system in the automobile industry, parameters matching between the control software and hardware parts have a remarkable influence on the vehicle handling. Nevertheless, this typical mechatronics subsystem is conventionally being addressed in a decoupled approach rather than an integrated method that leads to a comprehensive optimised system much closer to the Pareto optimal line. A new design approach of EPS is investigated by the simultaneous optimisation of integrated mechanical parameters and control parameters, compared with the individual optimisation control parameters and mechanical parameters. Objective evaluation of vehicle handling and stability is carried out in time domain and the frequency domain for evaluating the effect of optimisations. The investigation suggests that integrated optimisation of mechanical parameters and control parameters has significant positive impacts on vehicle handling and stability.

Analysis of Vehicle Steering and Driving Bifurcation Characteristics

The typical method of vehicle steering bifurcation analysis is based on the nonlinear autonomous vehicle model deriving from the classic two degrees of freedom (2DOF) linear vehicle model. This method usually neglects the driving effect on steering bifurcation characteristics. However, in the steering and driving combined conditions, the tyre under different driving conditions can provide different lateral force. The steering bifurcation mechanism without the driving effect is not able to fully reveal the vehicle steering and driving bifurcation characteristics. Aiming at the aforementioned problem, this paper analyzed the vehicle steering and driving bifurcation characteristics with the consideration of driving effect. Based on the 5DOF vehicle system dynamics model with the consideration of driving effect, the 7DOF autonomous system model was established. The vehicle steering and driving bifurcation dynamic characteristics were analyzed with different driving mode and driving torque. Taking the front-wheel-drive system as an example, the dynamic evolution process of steering and driving bifurcation was analyzed by phase space, system state variables, power spectral density, and Lyapunov index. The numerical recognition results of chaos were also provided. The research results show that the driving mode and driving torque have the obvious effect on steering and driving bifurcation characteristics.

Research on the Affection of Vehicle Lateral Stability Related to the Improved ABS

When automobile is braking in a turn, the left and right wheel load changes, often leads to excessive loss of vehicle steering stability. The process of steering is often accompanied with braking, we can improve the control strategy of anti-lock braking system which widely used in vehicles to maintain the steering-braking lateral stability.

The Governance of Quality Management in Dutch Health Care

This article gives a brief sketch of quality management in Dutch health care. Our focus is upon the governance of guideline development and quality measurement. Governance is conceptualized as the structure and process of steering of quality management. The governance structure of guideline development in the Netherlands can be conceptualized as a network without central coordination. Much depends upon the self-initiative of stakeholders. A similar picture can be found in quality measurement. Special attention is given to the development of care standards for chronic disease. Care standards have a broader scope than guidelines and take an explicit patient perspective. They not only contain evidence-based and up-to-date guidelines for the care pathway but also contain standards for self-management. Furthermore, they comprise a set of indicators for measuring the quality of care of the entire pathway covered by the standard. The final part of the article discusses the mission, tasks and strategic challenges of the newly established National Health Care Institute (Zorginstituut Nederland), which is scheduled to be operative in 2013.

Virtual test rig to improve the design and optimisation process of the vehicle steering and suspension systems

A virtual test rig is presented using a three-dimensional model of the elasto-kinematic behaviour of a vehicle. A general approach is put forward to determine the three-dimensional position of the body and the main parameters which influence the handling of the vehicle. For the design process, the variable input data are the longitudinal and lateral acceleration and the curve radius, which are defined by the user as a design goal. For the optimisation process, once the vehicle has been built, the variable input data are the travel of the four struts and the steering wheel angle, which is obtained through monitoring the vehicle. The virtual test rig has been applied to a standard vehicle and the validity of the results has been proven.

Feminist ‘Selves’ and Feminism's ‘Others’: Feminist Representations of Jamaat-E-Islami Women in Pakistan

In Pakistan, as in many other societies, politico-religious movements or so-called Islamist fundamentalist movements are becoming an important site for women's activism as well as the harnessing of such activism to promote agendas that seem to undermine women's autonomy. This has become a concern for a growing feminist literature which from a variety of political and theoretical positions seeks to understand and explain the subject-position of Muslim women as politico-religious activists. This paper attempts a deconstructive reading of texts by leading Pakistani feminist scholars as they attempt the difficult process of steering between fundamentalism and Orientalism in their accounts of ‘fundamentalist’ women in the political ideological space of Pakistan.

Digital mock-up design of the remote steerable ITER ECRH launching system

A 3D model is of vital interest to the entire development process of the remote steering (RS) electron cyclotron resonance heating (ECRH) top launcher. The aim is to have a digital model that continuously incorporates the latest developments of the overall design. This paper will present the results of the effort put in creating this 3D model and will discuss details about parameterized computer aided design (CAD), which enables the designer to integrate newly acquired insights on a much shorter timescale. Also, the detailed design of the steerable mirror mechanism will be presented.

Evaluation of the kinetics of electrostatically steered protein dimerization using Weighted-Ensemble Brownian dynamics

A number of recent studies have examined the roles of charged amino acid residues in guiding protein association. Motivating these studies is the hypothesis that patterns of charged amino acid residues cooperate electrostatically to assist in orienting the interacting proteins, increasing the rate of association. This ‘electrostatic steering’ effect is enhanced by decreasing the ionic strength in the surrounding solvent, and has been shown experimentally to raise the association rate coefficient several-fold. The present study employs a recent advance in the computational methodology of Brownian dynamics simulation to dissect the process of electrostatic steering in two model systems. A dimeric hemoglobin, whose constituent monomer is predicted to dimerize rapidly, and the adenosine diphosphate (ADP)-ribosylation factor ARF-1 from rat, shown to dimerize only at high concentrations, were approximated as spheres and the effects of their respective patterns of surface charges on dimerization kinetics were compared. The hemoglobin charge pattern yielded higher association rate coefficients consistently than did that of ARF-1 and the difference was especially pronounced when the charge patterns of each protein were applied to spheres the size of the other protein. In future work planned for this system, the detailed dissection of the roles of individual charges within the patterns on the surfaces of these proteins will indicate how the respective charge patterns dictate the observed association rates.

A Differential Game Model of Ship Control Process

In the paper the use of a differential game for describing the process of safe ship steering in the vicinity of a great number of ships is presented. It has been shown that a positional non-cooperative differential game of “j” participants is an adequate model of this process. The state equations of the process, the constraints for state variables and for control variables, initial and final conditions, and the form of pay-off have been formulated. Particular care was taken in considering different possible forms of the state equations. Different forms of state equations result from the possibility of identifying their coefficients, from the practical possibility of implementing control algorithms and from the scope of observability of process state when utilizing the information from the navigation system. As the optimum criterion for the differential game the minimum of loss of way caused by safety avoiding oncoming objects was adopted, as was at the same time the minimization of the risk of collision. The optimum strategies for the objects are calculated from the max min condition of the integral pay-off.

The Second Century Papers: Looking Ahead in Aeronautics—19

Navigation has been defined as “the business of conducting a craft as it moves about its ways“. This broad definition of navigation encompasses the whole process of handling, steering, control, guidance and operation of the craft in a safe and economic manner. Navigation has a much longer history than aeronautics. As man first began to explore the world and to develop trade, the need for safe and predictable operation of the craft was a spur to the application of the most advanced science and technology of the day.