1,227 research outputs found
Stability and dissipativity analysis of static neural networks with time delay
This paper is concerned with the problems of stability and dissipativity analysis for static neural networks (NNs) with time delay. Some improved delay-dependent stability criteria are established for static NNs with time-varying or time-invariant delay using the delay partitioning technique. Based on these criteria, several delay-dependent sufficient conditions are given to guarantee the dissipativity of static NNs with time delay. All the given results in this paper are not only dependent upon the time delay but also upon the number of delay partitions. Some examples are given to illustrate the effectiveness and reduced conservatism of the proposed results.published_or_final_versio
Static anti-windup compensator design for locally Lipschitz systems under input and output delays
This paper proposes a static anti-windup compensator (AWC) design methodology for the locally Lipschitz nonlinear systems, containing time-varying interval delays in input and output of the system in the presence of actuator saturation. Static AWC design is proposed for the systems by considering a delay-range-dependent methodology to consider less conservative delay bounds. The approach has been developed by utilizing an improved Lyapunov-Krasovskii functional, locally Lipschitz nonlinearity property, delay-interval, delay derivative upper bound, local sector condition, L2 gain reduction from exogenous input to exogenous output, improved Wirtinger inequality, additive time-varying delays, and convex optimization algorithms to obtain convex conditions for AWC gain calculations. In contrast to the existing results, the present work considers both input and output delays for the AWC design (along with their combined additive effect) and deals with a more generic locally Lipschitz class of nonlinear systems. The effectiveness of the proposed methodology is demonstrated via simulations for a nonlinear DC servo motor system, possessing multiple time-delays, dynamic nonlinearity and actuator constraints
Robust Controller for Delays and Packet Dropout Avoidance in Solar-Power Wireless Network
Solar Wireless Networked Control Systems (SWNCS) are a style of distributed control systems where sensors, actuators, and controllers are interconnected via a wireless communication network. This system setup has the benefit of low cost, flexibility, low weight, no wiring and simplicity of system diagnoses and maintenance. However, it also unavoidably calls some wireless network time delays and packet dropout into the design procedure. Solar lighting system offers a clean environment, therefore able to continue for a long period. SWNCS also offers multi Service infrastructure solution for both developed and undeveloped countries. The system provides wireless controller lighting, wireless communications network (WI-FI/WIMAX), CCTV surveillance, and wireless sensor for weather measurement which are all powered by solar energy
Robust Control
The need to be tolerant to changes in the control systems or in the operational environment of systems subject to unknown disturbances has generated new control methods that are able to deal with the non-parametrized disturbances of systems, without adapting itself to the system uncertainty but rather providing stability in the presence of errors bound in a model. With this approach in mind and with the intention to exemplify robust control applications, this book includes selected chapters that describe models of H-infinity loop, robust stability and uncertainty, among others. Each robust control method and model discussed in this book is illustrated by a relevant example that serves as an overview of the theoretical and practical method in robust control
Dynamics analysis and integrated design of real-time control systems
Real-time control systems are widely deployed in many applications. Theory and practice for the design and deployment of real-time control systems have evolved significantly. From the design perspective, control strategy development has been the focus of the research in the control community. In order to develop good control strategies, process modelling and analysis have been investigated for decades, and stability analysis and model-based control have been heavily studied in the literature. From the implementation perspective, real-time control systems require timeliness and predictable timing behaviour in addition to logical correctness, and a real-time control system may behave very differently with different software implementations of the control strategies on a digital controller, which typically has limited computing resources. Most current research activities on software implementations concentrate on various scheduling methodologies to ensure the schedulability of multiple control tasks in constrained environments. Recently, more and more real-time control systems are implemented over data networks, leading to increasing interest worldwide in the design and implementation of networked control systems (NCS). Major research activities in NCS include control-oriented and scheduling-oriented investigations. In spite of significant progress in the research and development of real-time control systems, major difficulties exist in the state of the art. A key issue is the lack of integrated design for control development and its software implementation. For control design, the model-based control technique, the current focus of control research, does not work when a good process model is not available or is too complicated for control design. For control implementation on digital controllers running multiple tasks, the system schedulability is essential but is not enough; the ultimate objective of satisfactory quality-of-control (QoC) performance has not been addressed directly. For networked control, the majority of the control-oriented investigations are based on two unrealistic assumptions about the network induced delay. The scheduling-oriented research focuses on schedulability and does not directly link to the overall QoC of the system. General solutions with direct QoC consideration from the network perspective to the challenging problems of network delay and packet dropout in NCS have not been found in the literature. This thesis addresses the design and implementation of real-time control systems with regard to dynamics analysis and integrated design. Three related areas have been investigated, namely control development for controllers, control implementation and scheduling on controllers, and real-time control in networked environments. Seven research problems are identified from these areas for investigation in this thesis, and accordingly seven major contributions have been claimed. Timing behaviour, quality of control, and integrated design for real-time control systems are highlighted throughout this thesis. In control design, a model-free control technique, pattern predictive control, is developed for complex reactive distillation processes. Alleviating the requirement of accurate process models, the developed control technique integrates pattern recognition, fuzzy logic, non-linear transformation, and predictive control into a unified framework to solve complex problems. Characterising the QoC indirectly with control latency and jitter, scheduling strategies for multiple control tasks are proposed to minimise the latency and/or jitter. Also, a hierarchical, QoC driven, and event-triggering feedback scheduling architecture is developed with plug-ins of either the earliest-deadline-first or fixed priority scheduling. Linking to the QoC directly, the architecture minimises the use of computing resources without sacrifice of the system QoC. It considers the control requirements, but does not rely on the control design. For real-time NCS, the dynamics of the network delay are analysed first, and the nonuniform distribution and multi-fractal nature of the delay are revealed. These results do not support two fundamental assumptions used in existing NCS literature. Then, considering the control requirements, solutions are provided to the challenging NCS problems from the network perspective. To compensate for the network delay, a real-time queuing protocol is developed to smooth out the time-varying delay and thus to achieve more predictable behaviour of packet transmissions. For control packet dropout, simple yet effective compensators are proposed. Finally, combining the queuing protocol, the packet loss compensation, the configuration of the worst-case communication delay, and the control design, an integrated design framework is developed for real-time NCS. With this framework, the network delay is limited to within a single control period, leading to simplified system analysis and improved QoC
An Empirical Analysis of the Forecast of Corporate Financial Distress in the European Energy Sector
openExploring the causes of corporate financial distress has been a topic of extensive discussion and research in the field of finance. Over the years, scholars and experts have dedicated their efforts to unraveling the intricacies behind financial struggles faced by businesses. The enduring interest in this subject can be attributed to the profound consequences that corporate financial distress can bring.
When a company finds itself in a state of financial distress, it often marks a critical turning point that could lead to insolvency or even bankruptcy. This represents the ultimate failure of the company and has wide-ranging impacts that go beyond its immediate boundaries. Employees are affected by potential job losses, stakeholders face financial losses, connected companies may experience disruptions in their operations, and the overall economy can suffer.
The costs associated with corporate financial distress are substantial and can take different forms. Direct costs include expenses related to legal proceedings, asset liquidation, and settling outstanding debts. Indirect costs can arise from the erosion of the company's reputation, diminished investor confidence, restricted access to credit, and the ripple effect felt throughout the supply chain.
Given the prevalence and far-reaching consequences of corporate financial distress, researchers and experts have delved into the topic with great fervor. Their aim is to develop models, methodologies, and strategies that can help identify early warning signs of financial distress and enable proactive measures to be taken. By doing so, they seek to protect companies from the brink of failure and promote stability and growth in the broader economy.
The study of corporate financial distress has yielded valuable insights into the various factors that contribute to these challenges. Researchers have examined aspects such as poor financial management practices, ineffective governance structures, unfavorable economic conditions, industry-specific challenges, and vulnerabilities unique to individual companies.
Ultimately, the research conducted in this field not only sheds light on the causes and consequences of corporate financial distress but also strives to provide guidance for companies, investors, and policymakers. By understanding the dynamics of financial distress, stakeholders can make informed decisions, implement preventive measures, and contribute to the resilience and success of businesses in the face of adversity.Exploring the causes of corporate financial distress has been a topic of extensive discussion and research in the field of finance. Over the years, scholars and experts have dedicated their efforts to unraveling the intricacies behind financial struggles faced by businesses. The enduring interest in this subject can be attributed to the profound consequences that corporate financial distress can bring.
When a company finds itself in a state of financial distress, it often marks a critical turning point that could lead to insolvency or even bankruptcy. This represents the ultimate failure of the company and has wide-ranging impacts that go beyond its immediate boundaries. Employees are affected by potential job losses, stakeholders face financial losses, connected companies may experience disruptions in their operations, and the overall economy can suffer.
The costs associated with corporate financial distress are substantial and can take different forms. Direct costs include expenses related to legal proceedings, asset liquidation, and settling outstanding debts. Indirect costs can arise from the erosion of the company's reputation, diminished investor confidence, restricted access to credit, and the ripple effect felt throughout the supply chain.
Given the prevalence and far-reaching consequences of corporate financial distress, researchers and experts have delved into the topic with great fervor. Their aim is to develop models, methodologies, and strategies that can help identify early warning signs of financial distress and enable proactive measures to be taken. By doing so, they seek to protect companies from the brink of failure and promote stability and growth in the broader economy.
The study of corporate financial distress has yielded valuable insights into the various factors that contribute to these challenges. Researchers have examined aspects such as poor financial management practices, ineffective governance structures, unfavorable economic conditions, industry-specific challenges, and vulnerabilities unique to individual companies.
Ultimately, the research conducted in this field not only sheds light on the causes and consequences of corporate financial distress but also strives to provide guidance for companies, investors, and policymakers. By understanding the dynamics of financial distress, stakeholders can make informed decisions, implement preventive measures, and contribute to the resilience and success of businesses in the face of adversity
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