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This chapter proposes a refined and updated measurement of the World's Economic Center of Gravity over the 1950–2008 period, based on historical data provided by Maddison (2010) and on the detailed grid data of the G-Econ (Nordhaus, 2006) database. The economic center of gravity is located in the vicinity of Iceland during the first three decades, and then heads strongly toward the East since 1980. Regarding geographic concentration, world production is less concentrated than population across the Earth's surface, and becomes even less so over time. A new decomposition technique is proposed, which suggests a structural break at the end of the 1970s. Measures of R&D activity, education expenditures and literacy as growth related indicators depict a spatial pattern that is consistent with the Eastern shift of the world economic center of gravity.

Most current lower extremity exoskeletons emphasize assistance for walking rather than stability. The purpose of this paper is to propose a rehabilitation gait based on the transfer of gravity center to improve the balance of exoskeleton rehabilitation training of the hemiplegic patients in the frontal plane, reducing the dependence on crutches/walking frames.

The real-time and predictable instability factors of human and exoskeleton system (HES) are analyzed. Inspired by the walking balance strategy of the blind, a rehabilitation gait based on the transfer of gravity center is proposed and studied by modeling and experimental test and is finally applied to the prototype – Zhejiang University lower extremity exoskeleton (ZJULEEX) – to verify its feasibility.

At least three real-time and predictable factors cause the instability of HES, and the factor of lateral tilt caused by gravity should be focused in the balance control of frontal plane. With the proposed gait, the hip height of stepping leg of HES does not reduce obviously even when the crutches do not work, which can improve the balance of HES.

However, the rehabilitation gait control needs to be more complete and intelligent to response to other types of perturbations to further improve the balance of HES. In addition, more clinical trials should be conducted to evaluate the effect of the proposed gait.

May bring happiness to the rehabilitation of patients with hemiplegia.

The rehabilitation gait based on the transfer of gravity center to improve the balance of HES is first proposed and applied to HES.

IN a series of articles entitled “Tailless Aircraft and Flying Wings”, concluded last month, the evolution of the tailless aeroplane and the flying wing was treated. The different trends of the development were classified, and a short discussion of the difficulties which had been experienced during experimental work given.

It is shown that location of objects (in the field of vision of “robot's eye”) with simple centre of gravity method (proposed by some authors) leads to severe errors in positioning. In the paper detailed quantitative analysis of two main types of these errors is carried out, as well as some methods of decreasing them are proposed, as applied in application programs for the computer image processing system CPO‐2.

The purpose of this paper is to analyze the characteristics of spatio-temporal dynamics and the evolution of land use change is essential for understanding and assessing the status and transition of ecosystems. Such analysis, when applied to Horqin sandy land, can also provide basic information for appropriate decision-making.

By integrating long time series Landsat imageries and geographic information system (GIS) technology, this paper explored the spatio-temporal dynamics and evolution-induced land use change of the largest sandy land in China from 1983 to 2016. Accurate and consistent land use information and land use change information was first extracted by using the maximum likelihood classifier and the post-classification change detection method, respectively. The spatio-temporal dynamics and evolution were then analyzed using three kinds of index models: the dynamic degree model to analyze the change of regional land resources, the dynamic change transfer matrix and flow direction rate to analyze the change direction, and the barycenter transfer model to analyze the spatial pattern of land use change.

The results indicated that land use in Horqin sandy land during the study period changed dramatically. Vegetation and sandy land showed fluctuating changes, cropland and construction land steadily increased, water body decreased continuously, and the spatial distribution patterns of land use were generally unbalanced. Vegetation, sandy land and cropland were transferred frequently. The amount of vegetation loss was the largest. Water body loss was 473.6 km², which accounted for 41.7 per cent of the total water body. The loss amount of construction land was only 1.0 km². Considerable differences were noted in the rate of gravity center migration among the land use types in different periods, and the overall rate of construction land migration was the smallest. Moreover, the gravity center migration rates of the water body and sandy land were relatively high and were related to the fragile ecological environment of Horqin sandy land.

The results not only confirmed the applicability and effectiveness of the combined method of remote sensing and GIS technology but also revealed notable spatio-temporal dynamics and evolution-induced land use change throughout the different time periods (1983-1990, 1990-2000, 2000-2010, 2010-2014, 2014-2016 and 1983-2016).

The purpose of this paper is to further the understanding of the link between human capital and strategy across hierarchies.

Using data on personality traits as a proxy for strategy implementation success, empirical data included 1,738 Operational Personality Questionnaire personality traits assessments in one large multinational firm. Respondents spanned from top-management to white-collar employees. Besides personality traits, measures include employment level and employment status. In addition, a total of 43 interviews were performed on the employee-level, with middle managers, with senior managers, and with executive-level managers.

After a strategic shift, successful implementation of a human resource management (HRM) strategy decreased down through the hierachies. This has implications for a firm trying to realign its resources to a new strategy. If the strategic shift is large, this will pose a great problem as human capital further down in the hierarchy will not be aligned to the new strategy, but rather be aligned to the old strategy.

The findings are discussed using the concept of the strategic centre of gravity. The authors elaborate on the concept in terms of the origin, mass, and inertia of the strategic centre of gravity.

A successful strategic shift in this sense will to a great extent depend on how successful the implementation is at lower levels of hierarchy, thus pointing to the importance to considering this when designing and pursuing strategic change.

The research contributes to the HRM literature by furthering the understanding of aligning human capital on different organizational levels to strategy and by developing the concept of the strategic centre of gravity.

The three-axis simulator relies on the air film between the air bearing and the bearing seat to achieve weightlessness and the frictionless motion condition, which is essential for simulating the micro-disturbance torque of a satellite in outer space. However, at the beginning of the experiment, the disturbance torque caused by the misalignment between the center of gravity of the simulator and the center of rotation of the bearing is the most important factor restricting the use of the space three-axis simulator. In order to solve this problem, it is necessary to set the balance adjustment system on the simulator to compensate the disturbance torque caused by the eccentricity. The paper aims to discuss these issues.

In this paper, a study of L1 adaptive automatic balancing control method for micro satellite with motor without other actuators is proposed. L1 adaptive control algorithm adds the low-pass filter to the control law, which in a certain sense to reduce the high-frequency signal and speed up the response time of the controlled system. At the same time, by estimating the adaptive parameter uncertainty in object, the output error of the state predictor and the controlled object can be stabilized under Lyapunov condition, and the robustness of the system is also improved. The automatic balancing method of PID is also studied in this paper.

Through this automatic balancing mechanism, the gravity disturbance torque can be effectively reduced down to 10⁻⁶ Nm, and the automatic balancing time can be controlled within 7 s.

This paper introduces an automatic balancing mechanism. The experimental results show that the mechanism can greatly improve the convergence speed while guaranteeing the control accuracy, and ensuring the feasibility of the large angle maneuver of spacecraft three-axis simulator.

This article deals with some of the stability, control and handling problems that have arisen as a result of drastic changes in aircraft configuration coupled with the advent of supersonic flight at high altitude. The article will be published in two parts. The present part contains a brief introduction to the subject of aircraft stability and control in addition to a description of the longitudinal characteristics of supersonic aircraft. The second part will be published in our next issue, and will deal with the lateral characteristics of supersonic aircraft. Some of the problems encountered in the design of the flying control system for this type of aircraft and an indication of the methods and techniques used for solving the various stability problems are also presented in the second part.

Displacements of a miscible magnetic layer in a capillary tube under a moving ring‐shaped magnet are studied numerically. The magnet is adjusted dynamically to maintain a constant distance from the front mixing interface on the centerline. Control parameters, such as magnetic strength, effective viscosity variation due to magnetization, diffusion and the position of the magnet, are analyzed systematically. Motion of the magnetic layer is evaluated by two quantitative measurements, i.e. movement of center of gravity and spread of layer width. In general, the moving speed of the center of gravity depends only slightly on the magnetic strength, and is found slower at a higher viscosity ratio and a closer placement to the front interface as well if the magnet is placed amid the layer. A weaker spread occurs in situations of stronger magnetic strength, lower viscosity parameters and also placements near the rear interface. A multi‐front finger results if the magnet is positioned ahead of the front interface.

IN these notes I have attempted to describe the main features of longitudinal stability and control in the simplest possible terms, omitting the mathematical apparatus which makes this subject so formidable to those who are not constantly using it. Designers are certainly justified in complaining that most analyses of this subject contain, so to speak, so much XYZ that the ABC of the matter (if indeed there is one) is successfully hidden from them. In making a drastic attempt to return to ABC it must be realised that such a statement can be neither strictly accurate nor complete. Something will be gained, however, if it helps some designers to be clearer about what they are supposed to be doing in this part of their task, and why. The XYZ of the subject is, of course, indispensable to the working out of any particular problem of design A classified list of some useful recent British reports will be found in the Appendix.