Reconfiguration Action Research Articles

Modeling and performance analysis of novel quad‐tied PV array configuration under partial shading conditions

AbstractA photovoltaic (PV) cell is the smallest unit in an array that exhibits nonlinear characteristic curves. To gather the maximum amount of energy from a PV array under partial shading conditions (PSCs), it is necessary to follow the largest peak in the power–voltage (P–V) curve. PV cells are partially or totally shaded due to atmospheric conditions, which show multiple peaks in the PV curve. To overcome the losses occurring due to PSCs, PV array reconfiguration action is advisable. The authors of this work proposed a novel quad‐tied PV array configuration and compared its performance to that of other current configurations such as series‐parallel, total‐cross tied, and others in terms of global maximum power point tracking, mismatch loss, fill factor, and efficiency. The MATLAB/Simulink 2020a platform was used to generate PV array curves under various shading conditions.

How to overcome path dependency through resource reconfiguration

Firms reconfigure their resources when responding to changes in their external or internal environment, often by incorporating new knowledge and resources in collaboration with external stakeholders. However, the reconfiguration process is challenging, costly, and often fails. The firm’s history plays an important role in the resource reconfiguration process being path dependent. Path dependency, debatably, leads to lock-in effects that prevent reconfiguration. However, we argue that this is a very limited viewpoint. In this paper, drawing empirical evidence from the digital games industry, we contend that path dependency constrains the reconfiguration action space and can potentially improve strategic planning by identifying the paths of least resistance. Depending on the extent of the reconfiguration, we identify two alternatives: direct reconfiguration (horizontal reconfiguration) or increasing the complexity by incorporating additional configurations (vertical reconfiguration).

A mission oriented reconfiguration technology for Spaceborne FPGA

Reconfigurable technology based on FPGA is increasingly used in satellites to meet the demand of the increasing missions that satellites need to complete in recent years. In this paper, a mission oriented reconfiguration technology for spaceborne FPGA is introduced to address the problem that how to meet the demand of satellite reconfiguration mission to orbit, execution time and FPGA resource requirements. Satellite reconfiguration system is divided into three parts, that is, mission management module, reconfiguration management module and reconfigurable FPGA. Firstly, a mission list is set up to record the mission’s execution time and space attributes, hardware space attributes and priority attributes. The mission is allocated to the FPGA resource area correspondingly based on the flexible region model. According to the time attribute and priority attribute of the mission, the reconfiguration management module carries out the reconfiguration action. And the reconfiguration management module mainly deals with reconfiguration library management and the entire or partial reconfiguration according to the configuration file. After the reconfigurable bit files are loaded to FPGA, the transformation and execution of the hardware resources from the mission to the hardware are completed. Finally, an evaluation of the real-time performance, reliability and security of the design is carried out. Experiments that based on a verification system composed of raspberry/PI and ZYNQ are conducted and results fully prove that the design in this paper can support mission oriented spaceborne FPGA reconfiguration.

Metrics on Energy Efficiency for Cognitive Green Equipment Based on FPGA Platform

In order to efficiently manage the power consumption of communication devices, a management architecture is necessary to sense the working state of the equipment and the ambient environment. Therefore, it is important to properly select energy-efficient metrics that reflect the working environment. Then, on the basis of the metrics obtained, an optimal decision can be made and is followed by a reconfiguration action, the aim of which is to minimize the power dissipation while not compromising the performance. In this paper, we would like to introduce some useful metrics for a cognitive management architecture when it is implemented on a field-programmable gate array platform and the methods used to get them. We also study the use case of some of the metrics, and the results are useful in providing the necessary information for decision making. There is a tradeoff between the power consumption, the performance, and the resources. A decision maker has to choose an optimal solution according to the working environment.

Two‐stage Kalman filter‐based actuator/surface fault identification and reconfigurable control applied to F‐16 fighter dynamics

SUMMARYIn this study, an active fault‐tolerant control technique with reconfiguration against actuator/surface failures is presented. A two‐stage Kalman filter is designed in order to identify the control distribution matrix elements that correspond to the faulty actuator/surface; thus, the control reconfiguration is carried out using this identified control distribution matrix. The actuator/surface fault identification problem is solved through two jointly operating Kalman filters: the first one is for the estimation of the control distribution matrix elements that correspond to the faulty actuator/surface, and the second one is for the estimation of the state variables of the aircraft model.A structure for the active fault‐tolerant aircraft flight control system with reconfiguration against actuator/surface failures is presented. A control reconfiguration action is taken in order to keep the performance of the impaired aircraft the same as that of the unimpaired aircraft.In simulations, the nonlinear flight dynamics of an AFTI/F‐16 fighter model is considered, and the performance of the proposed actuator/surface failure identification and reconfigurable control schemes are examined for this model. Copyright © 2012 John Wiley & Sons, Ltd.

Reconfiguración Dinámica de Sistemas Distribuidos en Tiempo-Real Basada en Agentes

Currently distributed systems are present in several applications in industry and research, such systems are restricted to time conditions. The presence of failures in these time critical systems requires decision making to avoid loss of deadlines, performance, instability or total suspension of the system. A strategy for achieving this is the dynamic reconfiguration of the structure of the system aimed at counteracting the effect of such failures. This article presents a proposal for dynamic and distributed reconfiguration considering each element of the distributed system as an agent with communication and cooperation capabilities to act joint with other agents to generate a reconfiguration action. These actions are the modification of sampling periods of sensors agents, decreased activity of the agents with fails and/or use of voting algorithms. For each type of system failure correspond a particular type of reconfiguration which is reached based on exchange of information between agents and the agreement they reached. The proposed dynamic reconfiguration scheme is implemented in the flight control of a prototype helicopter with two propellers through the inclusion in the closed loop control of a distributed system that uses a common communication media. The results of the reconfigured system response are obtained through numerical simulations carried out using Matlab and Simulink, as Real- Time simulation tool was used TrueTime.

Set-point reconfiguration approach for the FTC of wind turbines

AbstractIn this paper, a two-level reconfiguration action is used to design an FTC system. The objective is to adapt the corrective action accordingly to the fault severity. The first level of the procedure is triggered when the impact of the fault on the system performance is limited. At the second level a dynamic reference modification based on reference-offset governor is proposed. The idea consists of updating the controller by the new post-fault system model in first time and; in second time; modifying the set-point or reference according to the system constraints which become more strict after fault occurrence in order to avoid any actuator saturation and ensure system stability. The effectiveness of the proposed solution is illustrated by a wind turbine example subjects to actuator faults and constrained on the actuator dynamic ranges.

Smart Reconfigurable Fault-Tolerant Flight Control Against Actuator Failures

AbstractIn this study, active fault tolerant flight control technique with actuation reconfiguration is proposed. For this purpose two-stage Kalman filter (TSKF) is designed to identify the control distribution matrix elements corresponding to the faulty actuator, and a control reconfiguration action is taken to keep the performance of the impaired aircraft same as that of the unimpaired aircraft. Thus the control reconfiguration is carried out using identified control distribution matrix. In the simulations, the nonlinear flight dynamics of an AFTI/F-16 fighter model is considered, and actuator failure identification and reconfigurable control are examined.

Using Aspects for Enforcing Formal Architectural Invariants

Formal methods such as Z and Petri nets can be used to specify invariants that should hold during the execution of component-based applications such as those regarding changes in the architecture of the application and valid sequences of architecture reconfigurations. Integrating logic for checking and enforcing these invariants into the application's implementation is generally done by adding appropriate code to the functional application code. In this paper, we discuss several limitations of this approach that may ensue in a disconnection between the application implementation and its formal specification.We propose an approach for specifying and enforcing architectural constraints, which combines formal methods and Aspect-Oriented Programming. We use the Z notation for describing the architectural invariants of the application and Petri nets for modeling coordination protocols. At the implementation level, aspects intercept architecture reconfiguration events and check according to the formal specification and the coordination protocol whether a reconfiguration action can be performed.

Control Reconfiguration of Discrete Event Systems With Dynamic Control Specifications

This paper defines a reconfiguration method for the class of discrete-event systems (DES) that is subject to linear constraints as their control specifications. Some existing methods for enforcing these constraints make use of Petri-net P-invariants for controller synthesis. These methods are quite appealing because their computational complexity is much more tractable than most other methods for controller synthesis. However, a common limitation of all existing P-invariant-based control architectures for DES plants is the assumption that the linear constraints defining the control specification of the plant do not change over time. Here, we relax this assumption and allow the control specifications to change during controller runtime. Under certain assumptions on DES behavior, we automatically reconfigure the DES controller after the control specification is changed. In addition, if the current state of the controlled DES has become infeasible under the new control specification, we automatically generate a so-called plant reconfiguration procedure whose execution leads the system back to a feasible state. This reconfiguration procedure is optimal in that it seeks to minimize the cost of reconfiguration actions through an Integer Programming (IP) model. The objective function of the IP model can be used to generate reconfiguration solutions that meet some desired properties. Depending on the cost of each reconfiguration action, a minimum cost reconfiguration solution may use only actions contained in the current plant configuration (an internal response), or ask for a change in the plant configuration, for instance, by adding new resources (an external response), or a combination of both strategies. Finally, we illustrate our method by applying it to a hospital control system example. Note to Practitioners-This paper proposes a dynamic reconfiguration framework that can revise the operations of systems whose control requirements change over time. The proposed framework can be applied to systems that satisfy the following two assumptions. First, the behavior of the system under study is described in terms of a set of discrete states and events. Events will cause the system to transition between states. Second, the control requirements must be expressed by linear equalities and inequalities on the system states. Under these circumstances, the proposed framework can identify an optimal transition to a new control policy that satisfies the new control requirements. Moreover, the system under consideration will continue operating while this transition is taking place. One application of this method is in modifying hospital control strategies when a hospital experiences unexpected events. In this case, the hospital operations-such as patient handling, resource assignment, and procedure scheduling-can be represented by discrete state models (e.g., Petri nets). Constraints on these operations can be modeled by linear inequalities on hospital and patient state. Upon a change in the constraints, the proposed reconfiguration method revises the hospital control strategies. For example, a shift in the hospital service demands (e.g., an increase in the flow of patients to the hospital due to a mass casualty situation) can be translated to changes in the constraints. In this case, the hospital operations must be revised to accommodate the new constraints without disrupting the operation of the hospital. The reconfiguration method of this paper provides a framework for modeling the reconfiguration steps and for calculating the least cost reconfiguration solution.

Equipment management issues in B3G, end-to-end reconfigurable systems

The evolution of wireless communications in recent years has resulted in a clear trend toward Beyond Third Generation (B3G) systems, which support the integration and co-existence of multiple, diverse radio access technologies (RATs) in a common composite radio environment. The reconfigurability concept has been developed for the facilitation of B3G Systems. Reconfigurability supports the B3G concept by providing technologies that enable equipment (terminals and network elements) to dynamically select the most appropriate reconfiguration action. In this direction this article outlines some key issues for embedding reconfigurability functionality in equipment. A generic management system for reconfigurable equipment (MSRE) in B3G environments is presented and the functionality of its main components is described in detail.

Optimal redundancy management in reconfigurable control systems based on normalized nonspecificity

In this paper, the notion of normalized nonspecificity is introduced. The nonspecificity measures the uncertainty of the estimated parameters that reflect impairment in a controlled system. Based on this notion, a quantity called a reconfiguration coverage is calculated. It represents the likelihood of success of a control reconfiguration action. This coverage links the overall system reliability to the achievable and required control, as well as diagnostic performance. The coverage, when calculated on-line, is used for managing the redundancy in the system.