Kun Liu

This book highlights the fundamental theories and prediction methods of radiowave propagation for the design, building, and operation of contemporary satellite systems. The primary objective of this book is to inquire into whether and how it is possible in a democracy to effectively decrease short-sighted policies. Although the commonplace expression “responsibility to future generations” has become firmly established in public and political vocabulary, its operational meaning and practice are not as well understood and have not yet been systematically evaluated. It still has not been successfully translated into viable ethical and theoretical concepts that can guide public policies and action. How can modes of governance and established priorities compatible with the well-being of future generations be created? This book identifies the conditions, and the obstacles, for such future-oriented governance. To meet the needs of diverse satellite applications, the book covers the main factors that affect radiowave propagation, including the clear-air effects, the hydrometeor effects, the ionospheric effects, the earth's surface reflection, and the local environmental effects. To enhance the prediction of radiowave propagation, the book elaborates on the characteristics of radio meteorological and ionospheric environments. It also summarizes research progress on the prediction methods of radio noise and interference coordination for satellite systems. The fade mitigation techniques and the propagation analysis of satellite system design are discussed. Providing a comprehensive summary of common practices and latest advances, the book is intended for researchers and engineers engaged in the study and practice of satellite systems, radio propagation, and its applications.

This book presents a time-delay approach to the analysis and synthesis of networked control systems (NCSs) under communication constraints. Differently from other approaches, the time-delay approach to NCSs allows communication delays to be larger than the sampling intervals in the presence of scheduling protocols. The book starts from a comprehensive introduction to three main approaches to sampled-data and networked control. It then focuses on time-delay approach, and the modelling of the closed-loop systems in the form of time-delay system. It presents discontinuous (in time) Lyapunov functional constructions that are efficient for NCSs in the presence of communications delays. Further, it highlights time-delay approaches developed to model and analyze NCSs under communication constraints, with a particular focus on dynamic quantization, round-robin, try-once-discard and stochastic protocols. The results are first presented for the continuous-time NCSs and then extended to discrete-time NCSs. Discussing recent developments in Lyapunov-based analysis of NCSs under communication constraints, the book is a valuable resource for researchers interested in sampled-data and networked control, and time-delay systems, as well as for graduate students in automatic control and systems theory.

This book presents a time-delay approach to the analysis and synthesis of networked control systems (NCSs) under communication constraints. Differently from other approaches, the time-delay approach to NCSs allows communication delays to be larger than the sampling intervals in the presence of scheduling protocols. The book starts from a comprehensive introduction to three main approaches to sampled-data and networked control. It then focuses on time-delay approach, and the modelling of the closed-loop systems in the form of time-delay system. It presents discontinuous (in time) Lyapunov functional constructions that are efficient for NCSs in the presence of communications delays. Further, it highlights time-delay approaches developed to model and analyze NCSs under communication constraints, with a particular focus on dynamic quantization, round-robin, try-once-discard and stochastic protocols. The results are first presented for the continuous-time NCSs and then extended to discrete-time NCSs. Discussing recent developments in Lyapunov-based analysis of NCSs under communication constraints, the book is a valuable resource for researchers interested in sampled-data and networked control, and time-delay systems, as well as for graduate students in automatic control and systems theory.