Introduction

The postwar French state struggled to find the right balance between quantity and quality in the agricultural sector. European integration and the general drive to modernize the French economy drove French planners to push for greater productivity, while simultaneously drawing on the French reputation for quality artisanal production in order to market food stuffs to foreign consumers. The end result was a food system split between the big-box food store and the open-air market. This push for higher productivity launched a wave of Schumpeterian creative destruction that put many farmers out of business. One of the most important tools available to the proponents of agricultural industrialization was land use policy. Through the consolidation of holdings, farms achieved greater efficiency while farmers were pushed off their lands.

An Energy Efficient Hydraulic Winch Drive Concept Based on a Speed-Variable Switched Differential Pump

The application of valve driven hydraulic winch drives is related to substantial power losses, primarily due to throttle generated valve flows. More energy efficient solutions are also commonly applied in terms of conventional hydrostatic closed circuit drives as well as so-called secondary controls. Such solutions are typically constituted by many and rather expensive components, and are furthermore often suffering from low frequency dynamics. In this paper an alternative solution is proposed for winch drive operation, which is based on the so-called speed-variable switched differential pump, originally designed for direct drive of hydraulic differential cylinders. This concept utilizes three pumps, driven by a single electric servo drive. The concept is redesigned for usage in winch drives, driven by flow symmetric hydraulic motors and single directional loads as commonly seen in e.g. active heave compensation applications. A general drive configuration approach is presented, along with a proper control strategy and design. The resulting concept is evaluated when applied for active heave compensation. Results demonstrate control performance on level with conventional valve solutions in terms of motion tracking, however with improved efficiency, especially in the event that the electrical servo drive can realize four quadrant operation.

Complex Projective Synchronization in Drive-Response Stochastic Complex Networks by Impulsive Pinning Control

The complex projective synchronization in drive-response stochastic coupled networks with complex-variable systems is considered. The impulsive pinning control scheme is adopted to achieve complex projective synchronization and several simple and practical sufficient conditions are obtained in a general drive-response network. In addition, the adaptive feedback algorithms are proposed to adjust the control strength. Several numerical simulations are provided to show the effectiveness and feasibility of the proposed methods.

Adaptive Synchronization of One-Dimensional Discrete Chaotic Systems on Complex Networks

A method of adaptive synchronization of one-dimensional discrete chaotic systems on complex networks is proposed. The nodes of complex networks are constructed by one-dimensional discrete chaotic systems, we consider a general drive-response synchronization model of one-dimensional discrete chaotic systems on complex dynamical networks. Based on the adaptive control technique, the parameter adaptive laws and property conversion laws are given to achieve synchronization and parameters identification simultaneously. Simulation results show that the arithmetic average and geometric mean of all the nodes states are equal, furthermore, the unknown node parameters can be successfully identified, all nodes are transformed to drive nodes. This indicates that chaos synchronization is reached in the whole networks.

Lexical contrast maintenance and the organization of sublexical contrast systems

Variationist/evolutionary models of phonology assume a causal chain that links biases at the utterance level to the development and consolidation of abstract phonological patterns over time. Some of the properties of linguistic cognition that have been proposed to underlie this chain are (i) storage of experienced detail at multiple levels of description, (ii) feedback between perception and production, (iii) a similarity bias in the production and perception of variation, and (iv) enhancement of cues to potentially ambiguous lexical items in usage. I review evidence for these properties and argue that they interact to provide a pathway for individual usage events to influence the evolution of contrastive sublexcal category systems, i.e phoneme inventories. Specifically, the proposed Network-Feedback model predicts that the organization of sublexical category systems is shaped by a conflict between a general drive toward greater similarity among sublexical categories on the one hand, and a bias toward maintaining contrast between tokens of competing lexical categories on the other. The model provides testable hypotheses about the conditions favoring phoneme merger, chain-shifts, and phonemic splits, and more generally about the influence of lexical contrast on the packing of sublexical categories along gestural/perceptual dimensions. Finally, this pathway of change is consistent with proposals that sublexical categories such as features and segments are not primitives of language, but emerge through more general properties of performance, perception, categorization and learning.

Hopf Bifurcation and Feedback Control of Self-Excited Torsion Vibration in the Drive System

According to the general drive system consisting of motor, gear reducer and working-load, a torsion dynamics model with three-degree-of-freedom is established, in which the nonlinear resistance torque is considered. Based on the Hurwitz algorithm criterion, the Hopf bifurcation and critical points are analyzed and the stable parameter domains are obtained. Furthermore introducing the feedback controller into the initial system, the stability of self-excited vibration originating from the way of Hopf bifurcation is investigated. The critical parameters can be shifted by adjusting the linear gain for the purpose of enlarging the stable parameter domains. Applying the central manifold theorem, the amplitude of periodic motion and the unstable divergent vibration can be suppressed through selecting appropriate nonlinear control parameter. In addition, all these theoretical results are verified by numerical simulation.

The Global Trend towards Devolution and its Implications

Globalisation has been accompanied by an equally global tendency towards devolution of authority and resources from nation-states to regions and localities that takes on various forms, depending upon which actors are driving the decentralisation efforts. The existence of a general trend towards devolution also has significant implications for efficiency, equity, and administration. The authors outline first the general drive towards devolution and then proceed to examine which countries are experiencing which forms of decentralisation. A theoretical argument emphasising the role of governmental legitimacy across various tiers of government is used to explain the diversity of devolution initiatives, drawing on examples that include Brazil, Mexico, India, China, the USA, and some European countries. Having supported their model of decentralisation, the authors then examine the implications of the widespread downward transfer of power towards regions. Some of the less widely discussed pitfalls of decentralisation are presented; caution in promoting devolutionary efforts is the prescription of this paper.

High-Cycle Fatigue of Shafts due to Starting Transients in Drive Systems

This paper investigates some of the effects that structural characteristics and main non-linearities of a drive system have on systems response and its shaft fatigue. In the suggested approach a general drive system, including a motor, load and speed reducers, is modelled as a multi-degree-of-freedom torsional vibrations non-linear system. The differential equations of the system are formed automatically. The user of the developed program must input just the constants of the components. An algorithm to compute the loss of life of the shafts due to fatigue is also incorporated into the program. As an example, a drive system, including a motor, a speed reducer and load is modelled and tested under starting conditions. The effects of changing spring constants of the shafts and the backlash of the speed reducer are investigated.

A Method for Inverse Robot Calibration

A method is described for the inverse calibration of a manipulator or robot. Inverse calibration is defined to be finding the joint angles necessary to drive a robot to a desired endpoint location. The joint angles recommended by the robot controller’s internal model will not, in general, drive the robot to the desired location because of inaccuracies in this model. Inverse calibration seeks to reduce the error. Unlike previous work in calibration, the method reported here does not require modeling any specific phenomena that may cause the error; hence it is not limited in accuracy by inability to identify all the error sources. The method consists of finding approximation functions by which corrections are made to the encoder readings recommended by the robot’s internal model. These functions are found by measuring the error at discrete locations throughout a region of the robot’s workspace and then least-squares fitting third order trivariate polynomials to the error samples. A forward calibration (one which reports actual tool location from given encoder readings) based on the above method is also described. The inverse calibration is tested on a six DOF PUMA simulation. Results show that the endpoint location error can be reduced from an average of about 1.2 mm down to an average of about 0.12 mm.