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In order to meet the requirements of 6σ management and to overcome the deficiencies of the theory for using the pre-control chart to evaluate and monitor quality stability, the purpose of this paper is to probe into the quality stability evaluation and monitoring guidelines of small batch production process based on the pre-control chart under the conditions of the distribution center and specifications center non-coincidence (0<ɛ≤1.5σ), the process capability index C _p ≥2 and the virtual alarm probability α=0.27 percent.

First, the range of the quality stability evaluation sampling number in initial production process is determined by using probability and statistics methods, the sample size for the quality stability evaluation is adjusted and determined in initial production process according to the error judgment probability theory, and the guideline for quality stability evaluation has been proposed in initial production process based on the theory of small probability events. Second, the alternative guidelines for quality stability monitoring and control in formal production process are proposed by using combination theory, the alternative guidelines are initially selected based on the theory of small probability events, a comparative analysis of the guidelines is made according to the average run lengths values, and the monitoring and control guidelines for quality stability are determined in formal production process.

The results obtained from research indicate that when the virtual alarm probability α=0.27 percent, the shifts ɛ in the range 0<ɛ≤1.5σ and the process capability index C _p ≥2, the quality stability evaluation sample size of the initial production process is 11, whose scondition is that the number of the samples falling into the yellow zone is 1 at maximum. The quality stability evaluation sample size of the formal production process is 5, and when the number of the samples falling into the yellow zone is ≤1, the process is stable, while when two of the five samples falling into the yellow, then one more sample needs to be added, and only if this sample falls into the green zone, the process is stable.

Research results can overcome the unsatisfactory 6σ management assumptions and requirements and the oversize virtual alarm probability α of the past pre-control charts, as well as the shortage only adaptable to the pre-control chart when the shifts ɛ=0. And at the same time, the difficult problem hard to adopt the conventional control charts to carry out process control because of a fewer sample sizes is solved.

This booklet, available free of charge from Inspection Equipment, 19 Broad Court, Drury Lane, London, W.C.2, is a condensed report of the proceedings of the Second Conference on Aircraft Radiography held in Copenhagen from October 9–12, 1956.

THE present paper gives, in abbreviated form, the theory of blade motion and of static and dynamic stability of single‐rotor helicopters. Limitations of space do not permit of full discussion and the article should be taken as only an introduction to the somewhat complex problems of helicopter stability and control.

The purpose of this study is to propose a torque vectoring control system for improving the handling stability of distributed drive electric buses under complicated driving conditions. Energy crisis and environment pollution are two key pressing issues faced by mankind. Pure electric buses are recognized as the effective method to solve the problems. Distributed drive electric buses (DDEBs) as an emerging mode of pure electric buses are attracting intense research interests around the world. Compared with the central driven electric buses, DDEB is able to control the driving and braking torque of each wheel individually and accurately to significantly enhance the handling stability. Therefore, the torque vectoring control (TVC) system is proposed to allocate the driving torque among four wheels reasonably to improve the handling stability of DDEBs.

The proposed TVC system is designed based on hierarchical control. The upper layer is direct yaw moment controller based on feedforward and feedback control. The feedforward control algorithm is designed to calculate the desired steady-state yaw moment based on the steering wheel angle and the longitudinal velocity. The feedback control is anti-windup sliding mode control algorithm, which takes the errors between actual and reference yaw rate as the control variables. The lower layer is torque allocation controller, including economical torque allocation control algorithm and optimal torque allocation control algorithm.

The steady static circular test has been carried out to demonstrate the effectiveness and control effort of the proposed TVC system. Compared with the field experiment results of tested bus with TVC system and without TVC system, the slip angle of tested bus with TVC system is much less than without TVC. And the actual yaw rate of tested bus with TVC system is able to track the reference yaw rate completely. The experiment results demonstrate that the TVC system has a remarkable performance in the real practice and improve the handling stability effectively.

In view of the large load transfer, the strong coupling characteristics of tire , the suspension and the steering system during coach corning, the vehicle reference steering characteristics is defined considering vehicle nonlinear characteristics and the feedforward term of torque vectoring control at different steering angles and speeds is designed. Meanwhile, in order to improve the robustness of controller, an anti-integral saturation sliding mode variable structure control algorithm is proposed as the feedback term of torque vectoring control.

THE complexity of the problems which are associated with the lateral stability and directional control of tailless aeroplanes was not realized until rather late.

The purpose of this paper is to draw attention to a void in the literature on enterprise flexibility: The Management Control Systems’ (MCS) role in the enterprise flexibility and stability discussion. MCS can be instrumental in securing an organization’s strategic performance objectives, far beyond the mere managerial control and accounting perspectives of traditional MCS’ roles.

This study is qualitative in nature, and presents a theoretical approach with a conceptual model to address enterprise flexibility and stability jointly; arguing that both should be part of the MCS’ design and implementation with a distinct strategic outlook. Several theoretical and practical arguments are presented which reinforce this thesis.

To operate optimally, enterprises must be able to manage their limited resources in efficient and effective manner. This is especially so when dealing with uncertainty and contingencies on an ongoing basis, while following a defined strategic choice. Such choices are expected to mirror enterprise flexibility types and measures without neglecting enterprise stability requirements, linking both to strategic performance measurement indicators.

Further work is needed to explore not only how different types of enterprise flexibility and stability measures can bring additional benefits to the firm but also how best to apply such types in accordance with business and operations strategies, organizational stability requirements and management control strategies.

MCS can and should take part of an organization’s strategic performance measures but these are to be understood from a systemic design perspective of the enterprise system’s metacontrollability, addressing flexibility and stability jointly.

There is a need to reevaluate the role of MCS and their strategic potential. The approach presented can have valuable potential ramifications and insights for management and information sciences as well as for the enterprise management practitioners as a whole.

This paper provides original research on enterprise flexibility and stability analysis, covering all aspects of MC and its role on the enterprise’s metacontrollability. Design and coordination of the seven basic elements which comprise MCS are analyzed, as well as how they influence one another. The paper includes two tables to illustrate the approach being proposed. Table I presents a classification of the literature reviewed in the paper while Table AI presents the choice of the theoretical lens on enterprise flexibility from other authors which contrasts with the model proposed. The role of MCS in the enterprise is also included.

In this article M. Isacco concludes his exposition of what he believes to be the underlying principles of flight by direct‐lift machines. He here surveys the types that have been built up to the present from the point of view of their stability characteristics. This involves a critical description of practically every helicopter built during the last thirty years. His paper therefore constitutes a history of all that has been done in this field of aeronautics in modern times

This paper aims to present a theoretical method for analyzing the stability and control of a hingeless helicopter in the presence of windshear.

In this paper, the stability and control of a hingeless helicopter in the presence of windshear are investigated. First, the rotary wing dynamic model considered is the one of flap‐pitch (including the elastic deformation of the control system)‐torsion coupling. The induced velocity nonuniform distribution derived from vortex theory is taken into account. Then, as for atmospheric turbulence, the linear windshear model is used for modeling the variation of wind field. Finally, according to the calculated results of the stability characteristic roots and the control response of the helicopter, the helicopter performance in wind shear field is analyzed, and some conclusions are obtained.

Some useful conclusions are obtained through sample analysis.

Although the analyses for stability and control of a hingeless helicopter in the presence of windshear could be obtained using the current method, the model of complex wind field will still be expected in future studies.

A very useful method for analyzing helicopter stability and control.

The proposed method is valid and available for the analysis of helicopter flight dynamics.

Studies of the hingeless rotor helicopter dynamic stability and control laws are conducted. A new method is given for the calculation of stability and controllability of a helicopter in flight condition with lateral velocity. First, the rotary wing dynamic model considered is the one of flap‐pitch (including the elastic deformation of control system) – torsion coupling. The induced velocity non‐uniform distribution derived from vortex theory is taken into account. Then, according to the established motion model of the helicopter, the effects of induced velocity distribution, flap‐pitch‐torsion coupling and lateral velocity on the stability and controllability of the helicopter are analyzed. Based on the analyses of dynamic stability of the helicopter, the unstable mode and the necessity of installation of stability augmentation system (SAS) are recognized. Finally, the control laws of SAS for helicopter pitching, rolling and yawing motions are presented. After establishing helicopter flight control state equations, the performance analyses and step response simulation for helicopter SAS are carried out.