Modelling systemic change in coupled socio-environmental systems

Abrupt systemic changes in ecological and socio-economic systems are a regular occurrence. While there has been much attention to studying systemic changes primarily in ecology as well as in economics, the attempts to do so for coupled socio-environmental systems are rarer. This paper bridges the gap by reviewing how models can be instrumental in exploring significant, fundamental changes in such systems. The history of modelling systemic change in various disciplines contains a range of definitions and approaches. Even so, most of these efforts share some common challenges within the modelling context. We propose a framework drawing these challenges together, and use it to discuss the articles in this thematic issue on modelling systemic change in coupled social and environmental systems. The differing approaches used highlight that modelling systemic change is an area of endeavour that would benefit from greater synergies between the various disciplines concerned with systemic change.     

Practical stabilization of a class of uncertain time-varying nonlinear delay systems

In this paper we deal with a class of uncertain time-varying nonlinear systems with a state delay. Under some assumptions, we construct some stabilizing continuous feedback, i.e. linear and nonlinear in the state, which can guarantee global uniform exponential stability and global uniform practical convergence of the considered system. The quadratic Lyapunov function for the nominal stable system is used as a Lyapunov candidate function for the global system. The results developed in this note are applicable to a class of dynamical systems with uncertain time-delay. Our result is illustrated by a numerical example.     

KS780划片机x轴伺服系统工作原理与维修

通过对KS780划片机x轴伺服系统基本工作原理的分析,明确反馈信号在伺服系统认识和维修中的核心地位。同时,维修实例中提及的一些器件检测方法,如运算放大器的检测等也具有一定的广泛性和实用性。内容全部源于实践,因此相信对以后类似系统的认识和维修也具有一定的实际使用价值。     

评估COA放大性能的方法

本文提出直接评估电流反馈运算放大器放大性能的方法。