Control and stabilization of decentralized systems

NASA Technical Reports Server (NTRS)

Byrnes, Christopher I.; Gilliam, David; Martin, Clyde F.

1989-01-01

Proceeding from the problem posed by the need to stabilize the motion of two helicopters maneuvering a single load, a methodology is developed for the stabilization of classes of decentralized systems based on a more algebraic approach, which involves the external symmetries of decentralized systems. Stabilizing local-feedback laws are derived for any class of decentralized systems having a semisimple algebra of symmetries; the helicopter twin-lift problem, as well as certain problems involving the stabilization of discretizations of distributed parameter problems, have just such algebras of symmetries.

Two controller design approaches for decentralized systems

NASA Technical Reports Server (NTRS)

Ozguner, U.; Khorrami, F.; Iftar, A.

1988-01-01

Two different philosophies for designing the controllers of decentralized systems are considered within a quadratic regulator framework which is generalized to admit decentralized frequency weighting. In the first approach, the total system model is examined, and the feedback strategy for each channel or subsystem is determined. In the second approach, separate, possibly overlapping, and uncoupled models are analyzed for each channel, and the results can be combined to study the original system. The two methods are applied to the example of a model of the NASA COFS Mast Flight System.

Decentralized stabilization for a class of continuous-time nonlinear interconnected systems using online learning optimal control approach.

PubMed

Liu, Derong; Wang, Ding; Li, Hongliang

2014-02-01

In this paper, using a neural-network-based online learning optimal control approach, a novel decentralized control strategy is developed to stabilize a class of continuous-time nonlinear interconnected large-scale systems. First, optimal controllers of the isolated subsystems are designed with cost functions reflecting the bounds of interconnections. Then, it is proven that the decentralized control strategy of the overall system can be established by adding appropriate feedback gains to the optimal control policies of the isolated subsystems. Next, an online policy iteration algorithm is presented to solve the Hamilton-Jacobi-Bellman equations related to the optimal control problem. Through constructing a set of critic neural networks, the cost functions can be obtained approximately, followed by the control policies. Furthermore, the dynamics of the estimation errors of the critic networks are verified to be uniformly and ultimately bounded. Finally, a simulation example is provided to illustrate the effectiveness of the present decentralized control scheme.

Iterative learning-based decentralized adaptive tracker for large-scale systems: a digital redesign approach.

PubMed

Tsai, Jason Sheng-Hong; Du, Yan-Yi; Huang, Pei-Hsiang; Guo, Shu-Mei; Shieh, Leang-San; Chen, Yuhua

2011-07-01

In this paper, a digital redesign methodology of the iterative learning-based decentralized adaptive tracker is proposed to improve the dynamic performance of sampled-data linear large-scale control systems consisting of N interconnected multi-input multi-output subsystems, so that the system output will follow any trajectory which may not be presented by the analytic reference model initially. To overcome the interference of each sub-system and simplify the controller design, the proposed model reference decentralized adaptive control scheme constructs a decoupled well-designed reference model first. Then, according to the well-designed model, this paper develops a digital decentralized adaptive tracker based on the optimal analog control and prediction-based digital redesign technique for the sampled-data large-scale coupling system. In order to enhance the tracking performance of the digital tracker at specified sampling instants, we apply the iterative learning control (ILC) to train the control input via continual learning. As a result, the proposed iterative learning-based decentralized adaptive tracker not only has robust closed-loop decoupled property but also possesses good tracking performance at both transient and steady state. Besides, evolutionary programming is applied to search for a good learning gain to speed up the learning process of ILC. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Decentralized control of sound radiation using iterative loop recovery.

PubMed

Schiller, Noah H; Cabell, Randolph H; Fuller, Chris R

2010-10-01

A decentralized model-based control strategy is designed to reduce low-frequency sound radiation from periodically stiffened panels. While decentralized control systems tend to be scalable, performance can be limited due to modeling error introduced by the unmodeled interaction between neighboring control units. Since bounds on modeling error are not known in advance, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by neighboring control loops, requires no communication between subsystems, and is relatively simple. The control strategy is evaluated numerically using a model of a stiffened aluminum panel that is representative of the sidewall of an aircraft. Simulations demonstrate that the iterative approach can achieve significant reductions in radiated sound power from the stiffened panel without destabilizing neighboring control units.

Decentralized Control of Sound Radiation Using Iterative Loop Recovery

NASA Technical Reports Server (NTRS)

Schiller, Noah H.; Cabell, Randolph H.; Fuller, Chris R.

2009-01-01

A decentralized model-based control strategy is designed to reduce low-frequency sound radiation from periodically stiffened panels. While decentralized control systems tend to be scalable, performance can be limited due to modeling error introduced by the unmodeled interaction between neighboring control units. Since bounds on modeling error are not known in advance, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by neighboring control loops, requires no communication between subsystems, and is relatively simple. The control strategy is evaluated numerically using a model of a stiffened aluminum panel that is representative of the sidewall of an aircraft. Simulations demonstrate that the iterative approach can achieve significant reductions in radiated sound power from the stiffened panel without destabilizing neighboring control units.

Is decentralization good for logistics systems? Evidence on essential medicine logistics in Ghana and Guatemala.

PubMed

Bossert, Thomas J; Bowser, Diana M; Amenyah, Johnnie K

2007-03-01

Efficient logistics systems move essential medicines down the supply chain to the service delivery point, and then to the end user. Experts on logistics systems tend to see the supply chain as requiring centralized control to be most effective. However, many health reforms have involved decentralization, which experts fear has disrupted the supply chain and made systems less effective. There is no consensus on an appropriate methodology for assessing the effectiveness of decentralization in general, and only a few studies have attempted to address decentralization of logistics systems. This paper sets out a framework and methodology of a pioneering exploratory study that examines the experiences of decentralization in two countries, Guatemala and Ghana, and presents suggestive results of how decentralization affected the performance of their logistics systems. The analytical approach assessed decentralization using the principal author's 'decision space' approach, which defines decentralization as the degree of choice that local officials have over different health system functions. In this case the approach focused on 15 different logistics functions and measured the relationship between the degree of choice and indicators of performance for each of the functions. The results of both studies indicate that less choice (i.e. more centralized) was associated with better performance for two key functions (inventory control and information systems), while more choice (i.e. more decentralized) over planning and budgeting was associated with better performance. With different systems of procurement in Ghana and Guatemala, we found that a system with some elements of procurement that are centralized (selection of firms and prices fixed by national tender) was positively related in Guatemala but negatively related in Ghana, where a system of 'cash and carry' cost recovery allowed more local choice. The authors conclude that logistics systems can be effectively decentralized for some functions while others should remain centralized. These preliminary findings, however, should be subject to alternative methodologies to confirm the findings.

Adaptive Decentralized Control

DTIC Science & Technology

1985-04-01

and implementation of the decentralized controllers. It raises, however, many difficult questions regarding the conditions under which such a scheme ...adaptive controller, and a general form of the model reference adaptive controller (4]. We believe that this work represents a significant advance in the...Comparing the adaptive system with the tuned system results in the development of a generic adaptive error system. Passivity theory was used to derive

Fully decentralized control of a soft-bodied robot inspired by true slime mold.

PubMed

Umedachi, Takuya; Takeda, Koichi; Nakagaki, Toshiyuki; Kobayashi, Ryo; Ishiguro, Akio

2010-03-01

Animals exhibit astoundingly adaptive and supple locomotion under real world constraints. In order to endow robots with similar capabilities, we must implement many degrees of freedom, equivalent to animals, into the robots' bodies. For taming many degrees of freedom, the concept of autonomous decentralized control plays a pivotal role. However a systematic way of designing such autonomous decentralized control system is still missing. Aiming at understanding the principles that underlie animals' locomotion, we have focused on a true slime mold, a primitive living organism, and extracted a design scheme for autonomous decentralized control system. In order to validate this design scheme, this article presents a soft-bodied amoeboid robot inspired by the true slime mold. Significant features of this robot are twofold: (1) the robot has a truly soft and deformable body stemming from real-time tunable springs and protoplasm, the former is used for an outer skin of the body and the latter is to satisfy the law of conservation of mass; and (2) fully decentralized control using coupled oscillators with completely local sensory feedback mechanism is realized by exploiting the long-distance physical interaction between the body parts stemming from the law of conservation of protoplasmic mass. Simulation results show that this robot exhibits highly supple and adaptive locomotion without relying on any hierarchical structure. The results obtained are expected to shed new light on design methodology for autonomous decentralized control system.

Taming instabilities in power grid networks by decentralized control

NASA Astrophysics Data System (ADS)

Schäfer, B.; Grabow, C.; Auer, S.; Kurths, J.; Witthaut, D.; Timme, M.

2016-05-01

Renewables will soon dominate energy production in our electric power system. And yet, how to integrate renewable energy into the grid and the market is still a subject of major debate. Decentral Smart Grid Control (DSGC) was recently proposed as a robust and decentralized approach to balance supply and demand and to guarantee a grid operation that is both economically and dynamically feasible. Here, we analyze the impact of network topology by assessing the stability of essential network motifs using both linear stability analysis and basin volume for delay systems. Our results indicate that if frequency measurements are averaged over sufficiently large time intervals, DSGC enhances the stability of extended power grid systems. We further investigate whether DSGC supports centralized and/or decentralized power production and find it to be applicable to both. However, our results on cycle-like systems suggest that DSGC favors systems with decentralized production. Here, lower line capacities and lower averaging times are required compared to those with centralized production.

Decentralized control of large flexible structures by joint decoupling

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Juang, Jer-Nan

1994-01-01

This paper presents a novel method to design decentralized controllers for large complex flexible structures by using the idea of joint decoupling. Decoupling of joint degrees of freedom from the interior degrees of freedom is achieved by setting the joint actuator commands to cancel the internal forces exerting on the joint degrees of freedom. By doing so, the interactions between substructures are eliminated. The global structure control design problem is then decomposed into several substructure control design problems. Control commands for interior actuators are set to be localized state feedback using decentralized observers for state estimation. The proposed decentralized controllers can operate successfully at the individual substructure level as well as at the global structure level. Not only control design but also control implementation is decentralized. A two-component mass-spring-damper system is used as an example to demonstrate the proposed method.

Robust control of multi-jointed arm with a decentralized autonomous control mechanism

NASA Technical Reports Server (NTRS)

Kimura, Shinichi; Miyazaki, Ken; Suzuki, Yoshiaki

1994-01-01

A decentralized autonomous control mechanism applied to the control of three dimensional manipulators and its robustness to partial damage was assessed by computer simulation. Decentralized control structures are believed to be quite robust to time delay between the operator and the target system. A 10-jointed manipulator based on our control mechanism was able to continue its positioning task in three-dimensional space without revision of the control program, even after some of its joints were damaged. These results suggest that this control mechanism can be effectively applied to space telerobots, which are associated with serious time delay between the operator and the target system, and which cannot be easily repaired after being partially damaged.

Decentralized Estimation and Control for Preserving the Strong Connectivity of Directed Graphs.

PubMed

Sabattini, Lorenzo; Secchi, Cristian; Chopra, Nikhil

2015-10-01

In order to accomplish cooperative tasks, decentralized systems are required to communicate among each other. Thus, maintaining the connectivity of the communication graph is a fundamental issue. Connectivity maintenance has been extensively studied in the last few years, but generally considering undirected communication graphs. In this paper, we introduce a decentralized control and estimation strategy to maintain the strong connectivity property of directed communication graphs. In particular, we introduce a hierarchical estimation procedure that implements power iteration in a decentralized manner, exploiting an algorithm for balancing strongly connected directed graphs. The output of the estimation system is then utilized for guaranteeing preservation of the strong connectivity property. The control strategy is validated by means of analytical proofs and simulation results.

On the decentralized control of large-scale systems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Chong, C.

1973-01-01

The decentralized control of stochastic large scale systems was considered. Particular emphasis was given to control strategies which utilize decentralized information and can be computed in a decentralized manner. The deterministic constrained optimization problem is generalized to the stochastic case when each decision variable depends on different information and the constraint is only required to be satisfied on the average. For problems with a particular structure, a hierarchical decomposition is obtained. For the stochastic control of dynamic systems with different information sets, a new kind of optimality is proposed which exploits the coupled nature of the dynamic system. The subsystems are assumed to be uncoupled and then certain constraints are required to be satisfied, either in a off-line or on-line fashion. For off-line coordination, a hierarchical approach of solving the problem is obtained. The lower level problems are all uncoupled. For on-line coordination, distinction is made between open loop feedback optimal coordination and closed loop optimal coordination.

Linear decentralized learning control

NASA Technical Reports Server (NTRS)

Lee, Soo C.; Longman, Richard W.; Phan, Minh

1992-01-01

The new field of learning control develops controllers that learn to improve their performance at executing a given task, based on experience performing this task. The simplest forms of learning control are based on the same concept as integral control, but operating in the domain of the repetitions of the task. This paper studies the use of such controllers in a decentralized system, such as a robot with the controller for each link acting independently. The basic result of the paper is to show that stability of the learning controllers for all subsystems when the coupling between subsystems is turned off, assures stability of the decentralized learning in the coupled system, provided that the sample time in the digital learning controller is sufficiently short.

Decentralized Adaptive Control of Systems with Uncertain Interconnections, Plant-Model Mismatch and Actuator Failures

NASA Technical Reports Server (NTRS)

Patre, Parag; Joshi, Suresh M.

2011-01-01

Decentralized adaptive control is considered for systems consisting of multiple interconnected subsystems. It is assumed that each subsystem s parameters are uncertain and the interconnection parameters are not known. In addition, mismatch can exist between each subsystem and its reference model. A strictly decentralized adaptive control scheme is developed, wherein each subsystem has access only to its own state but has the knowledge of all reference model states. The mismatch is estimated online for each subsystem and the mismatch estimates are used to adaptively modify the corresponding reference models. The adaptive control scheme is extended to the case with actuator failures in addition to mismatch.

Decentralized control

NASA Technical Reports Server (NTRS)

Steffen, Chris

1990-01-01

An overview of the time-delay problem and the reliability problem which arise in trying to perform robotic construction operations at a remote space location are presented. The effects of the time-delay upon the control system design will be itemized. A high level overview of a decentralized method of control which is expected to perform better than the centralized approach in solving the time-delay problem is given. The lower level, decentralized, autonomous, Troter Move-Bar algorithm is also presented (Troters are coordinated independent robots). The solution of the reliability problem is connected to adding redundancy to the system. One method of adding redundancy is given.

Decentralized stabilization of semi-active vibrating structures

NASA Astrophysics Data System (ADS)

Pisarski, Dominik

2018-02-01

A novel method of decentralized structural vibration control is presented. The control is assumed to be realized by a semi-active device. The objective is to stabilize a vibrating system with the optimal rates of decrease of the energy. The controller relies on an easily implemented decentralized switched state-feedback control law. It uses a set of communication channels to exchange the state information between the neighboring subcontrollers. The performance of the designed method is validated by means of numerical experiments performed for a double cantilever system equipped with a set of elastomers with controlled viscoelastic properties. In terms of the assumed objectives, the proposed control strategy significantly outperforms the passive damping cases and is competitive with a standard centralized control. The presented methodology can be applied to a class of bilinear control systems concerned with smart structural elements.

Minimal-Approximation-Based Decentralized Backstepping Control of Interconnected Time-Delay Systems.

PubMed

Choi, Yun Ho; Yoo, Sung Jin

2016-12-01

A decentralized adaptive backstepping control design using minimal function approximators is proposed for nonlinear large-scale systems with unknown unmatched time-varying delayed interactions and unknown backlash-like hysteresis nonlinearities. Compared with existing decentralized backstepping methods, the contribution of this paper is to design a simple local control law for each subsystem, consisting of an actual control with one adaptive function approximator, without requiring the use of multiple function approximators and regardless of the order of each subsystem. The virtual controllers for each subsystem are used as intermediate signals for designing a local actual control at the last step. For each subsystem, a lumped unknown function including the unknown nonlinear terms and the hysteresis nonlinearities is derived at the last step and is estimated by one function approximator. Thus, the proposed approach only uses one function approximator to implement each local controller, while existing decentralized backstepping control methods require the number of function approximators equal to the order of each subsystem and a calculation of virtual controllers to implement each local actual controller. The stability of the total controlled closed-loop system is analyzed using the Lyapunov stability theorem.

Reduced modeling of flexible structures for decentralized control

NASA Technical Reports Server (NTRS)

Yousuff, A.; Tan, T. M.; Bahar, L. Y.; Konstantinidis, M. F.

1986-01-01

Based upon the modified finite element-transfer matrix method, this paper presents a technique for reduced modeling of flexible structures for decentralized control. The modeling decisions are carried out at (finite-) element level, and are dictated by control objectives. A simply supported beam with two sets of actuators and sensors (linear force actuator and linear position and velocity sensors) is considered for illustration. In this case, it is conjectured that the decentrally controlled closed loop system is guaranteed to be at least marginally stable.

Modeling and stability of segmented reflector telescopes - A decentralized approach

NASA Technical Reports Server (NTRS)

Ryaciotaki-Boussalis, Helen A.; Ih, Che-Hang Charles

1990-01-01

The decentralization of a segmented reflector telescope based on a finite-element model of its structure is considered. The decentralization of the system at the panel level is considered. Each panel is originally treated as an isolated subsystem so that the controller design is performed independently at the local level, and then applied to the composite system for stability analysis. The panel-level control laws were designed by means of pole placement using local output feedback. Simulation results show a better 1000:1 vibration attenuation in panel position when compared to the open-loop system. It is shown that the overall closed-loop system is exponentially stable provided that certain conditions are met. The advantage to the decentralized approach is that the design is performed in terms of the low-dimensionality subsystems, thus drastically reducing the design computational complexities.

Neural-Network-Based Adaptive Decentralized Fault-Tolerant Control for a Class of Interconnected Nonlinear Systems.

PubMed

Li, Xiao-Jian; Yang, Guang-Hong

2018-01-01

This paper is concerned with the adaptive decentralized fault-tolerant tracking control problem for a class of uncertain interconnected nonlinear systems with unknown strong interconnections. An algebraic graph theory result is introduced to address the considered interconnections. In addition, to achieve the desirable tracking performance, a neural-network-based robust adaptive decentralized fault-tolerant control (FTC) scheme is given to compensate the actuator faults and system uncertainties. Furthermore, via the Lyapunov analysis method, it is proven that all the signals of the resulting closed-loop system are semiglobally bounded, and the tracking errors of each subsystem exponentially converge to a compact set, whose radius is adjustable by choosing different controller design parameters. Finally, the effectiveness and advantages of the proposed FTC approach are illustrated with two simulated examples.

Extended Decentralized Linear-Quadratic-Gaussian Control

NASA Technical Reports Server (NTRS)

Carpenter, J. Russell

2000-01-01

A straightforward extension of a solution to the decentralized linear-Quadratic-Gaussian problem is proposed that allows its use for commonly encountered classes of problems that are currently solved with the extended Kalman filter. This extension allows the system to be partitioned in such a way as to exclude the nonlinearities from the essential algebraic relationships that allow the estimation and control to be optimally decentralized.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2016-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking*

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:27990059

On the applicability of the decentralized control mechanism extracted from the true slime mold: a robotic case study with a serpentine robot.

PubMed

Sato, Takahide; Kano, Takeshi; Ishiguro, Akio

2011-06-01

A systematic method for an autonomous decentralized control system is still lacking, despite its appealing concept. In order to alleviate this, we focused on the amoeboid locomotion of the true slime mold, and extracted a design scheme for the decentralized control mechanism that leads to adaptive behavior for the entire system, based on the so-called discrepancy function. In this paper, we intensively investigate the universality of this design scheme by applying it to a different type of locomotion based on a 'synthetic approach'. As a first step, we implement this design scheme to the control of a real physical two-dimensional serpentine robot that exhibits slithering locomotion. The experimental results show that the robot exhibits adaptive behavior and responds to the environmental changes; it is also robust against malfunctions of the body segments due to the local sensory feedback control that is based on the discrepancy function. We expect the results to shed new light on the methodology of autonomous decentralized control systems.

A Two-Time Scale Decentralized Model Predictive Controller Based on Input and Output Model

PubMed Central

Niu, Jian; Zhao, Jun; Xu, Zuhua; Qian, Jixin

2009-01-01

A decentralized model predictive controller applicable for some systems which exhibit different dynamic characteristics in different channels was presented in this paper. These systems can be regarded as combinations of a fast model and a slow model, the response speeds of which are in two-time scale. Because most practical models used for control are obtained in the form of transfer function matrix by plant tests, a singular perturbation method was firstly used to separate the original transfer function matrix into two models in two-time scale. Then a decentralized model predictive controller was designed based on the two models derived from the original system. And the stability of the control method was proved. Simulations showed that the method was effective. PMID:19834542

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2017-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and [Formula: see text] robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and H2 robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:28959117

The Impact of Human-Automation Collaboration in Decentralized Multiple Unmanned Vehicle Control

DTIC Science & Technology

2011-01-01

based decentralized auctions for robust task allocation ,[ IEEE Trans. Robot., vol. 25, no. 4, pp...operators can aid such systems by bringing their knowledge- based reasoning and experience to bear. Given a decentralized task planner and a goal- based ...experience to bear. Given a decentralized task planner and a goal- based operator interface for a network of unmanned vehicles in a search, track,

OPTIMIZATION OF DECENTRALIZED BMP CONTROLS IN URBAN AREAS

EPA Science Inventory

This paper will present an overview of a recently completed project for the US EPA entitled, Optimization of Urban Wet-weather Flow Control Systems. The focus of this effort is on techniques that are suitable for evaluating decentralized BMP controls. The four major components ...

OPTIMIZATION OF DECENTRALIZED BMP CONTROLS IN URBAN AREAS

EPA Science Inventory

This paper will present an overview of a recently completed project for the US EPA entitled Optimization of Urban Wet-weather Flow Control Systems. The focus of this effort is on techniques that are suitable for evaluating decentralized BMP controls. The four major components o...

Concept of an innovative water management system with decentralized water reclamation and cascading material-cycle for agricultural areas.

PubMed

Fujiwara, T

2012-01-01

Unlike in urban areas where intensive water reclamation systems are available, development of decentralized technologies and systems is required for water use to be sustainable in agricultural areas. To overcome various water quality issues in those areas, a research project entitled 'Development of an innovative water management system with decentralized water reclamation and cascading material-cycle for agricultural areas under the consideration of climate change' was launched in 2009. This paper introduces the concept of this research and provides detailed information on each of its research areas: (1) development of a diffuse agricultural pollution control technology using catch crops; (2) development of a decentralized differentiable treatment system for livestock and human excreta; and (3) development of a cascading material-cycle system for water pollution control and value-added production. The author also emphasizes that the innovative water management system for agricultural areas should incorporate a strategy for the voluntary collection of bio-resources.

Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System

PubMed Central

Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

2016-01-01

This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks. PMID:27472338

Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System.

PubMed

Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

2016-07-27

This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks.

Feasibility of Decentralized Linear-Quadratic-Gaussian Control of Autonomous Distributed Spacecraft

NASA Technical Reports Server (NTRS)

Carpenter, J. Russell

1999-01-01

A distributed satellite formation, modeled as an arbitrary number of fully connected nodes in a network, could be controlled using a decentralized controller framework that distributes operations in parallel over the network. For such problems, a solution that minimizes data transmission requirements, in the context of linear-quadratic-Gaussian (LQG) control theory, was given by Speyer. This approach is advantageous because it is non-hierarchical, detected failures gracefully degrade system performance, fewer local computations are required than for a centralized controller, and it is optimal with respect to the standard LQG cost function. Disadvantages of the approach are the need for a fully connected communications network, the total operations performed over all the nodes are greater than for a centralized controller, and the approach is formulated for linear time-invariant systems. To investigate the feasibility of the decentralized approach to satellite formation flying, a simple centralized LQG design for a spacecraft orbit control problem is adapted to the decentralized framework. The simple design uses a fixed reference trajectory (an equatorial, Keplerian, circular orbit), and by appropriate choice of coordinates and measurements is formulated as a linear time-invariant system.

Power Source Status Estimation and Drive Control Method for Autonomous Decentralized Hybrid Train

NASA Astrophysics Data System (ADS)

Furuya, Takemasa; Ogawa, Kenichi; Yamamoto, Takamitsu; Hasegawa, Hitoshi

A hybrid control system has two main functions: power sharing and equipment protection. In this paper, we discuss the design, construction and testing of a drive control method for an autonomous decentralized hybrid train with 100-kW-class fuel cells (FC) and 36-kWh lithium-ion batteries (Li-Batt). The main objectives of this study are to identify the operation status of the power sources on the basis of the input voltage of the traction inverter and to estimate the maximum traction power control basis of the power-source status. The proposed control method is useful in preventing overload operation of the onboard power sources in an autonomous decentralized hybrid system that has a flexible main circuit configuration and a few control signal lines. Further, with this method, the initial cost of a hybrid system can be reduced and the retrofit design of the hybrid system can be simplified. The effectiveness of the proposed method is experimentally confirmed by using a real-scale hybrid train system.

Decentralized Control of Sound Radiation from an Aircraft-Style Panel Using Iterative Loop Recovery

NASA Technical Reports Server (NTRS)

Schiller, Noah H.; Cabell, Randolph H.; Fuller, Chris R.

2008-01-01

A decentralized LQG-based control strategy is designed to reduce low-frequency sound transmission through periodically stiffened panels. While modern control strategies have been used to reduce sound radiation from relatively simple structural acoustic systems, significant implementation issues have to be addressed before these control strategies can be extended to large systems such as the fuselage of an aircraft. For instance, centralized approaches typically require a high level of connectivity and are computationally intensive, while decentralized strategies face stability problems caused by the unmodeled interaction between neighboring control units. Since accurate uncertainty bounds are not known a priori, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by neighboring control loops, requires no communication between subsystems, and is relatively simple. The control strategy is validated using real-time control experiments performed on a built-up aluminum test structure representative of the fuselage of an aircraft. Experiments demonstrate that the iterative approach is capable of achieving 12 dB peak reductions and a 3.6 dB integrated reduction in radiated sound power from the stiffened panel.

The rise of governmentality in the Italian National Health System: physiology or pathology of a decentralized and (ongoing) federalist system?

PubMed

Lega, Federico; Sargiacomo, Massimo; Ianni, Luca

2010-11-01

In this paper, we aim to discuss the implications and lessons that can be learnt from the ongoing process of federalism affecting the Italian National Health System (INHS). Many countries are currently taking decisions concerning the decentralization or re-centralization of their health-care systems, with several key issues that are illustrated in the recent history of the INHS. The decentralization process of INHS has produced mixed results, as some regions took advantage of it to strengthen their systems, whereas others were not capable of developing an effective steering role. We argue that the mutual reinforcement of the decentralization and recentralization processes is not paradoxical, but is actually an effective way for the State to maintain control over the equity and efficiency of its health-care system while decentralizing at a regional level. In this perspective, we provide evidence backing up some of the assumptions made in previous works as well as new food-for thought - specifically on how governmentality and federalism should meet - to reshape the debate on decentralization in health care.

Towards a Decentralized Magnetic Indoor Positioning System

PubMed Central

Kasmi, Zakaria; Norrdine, Abdelmoumen; Blankenbach, Jörg

2015-01-01

Decentralized magnetic indoor localization is a sophisticated method for processing sampled magnetic data directly on a mobile station (MS), thereby decreasing or even avoiding the need for communication with the base station. In contrast to central-oriented positioning systems, which transmit raw data to a base station, decentralized indoor localization pushes application-level knowledge into the MS. A decentralized position solution has thus a strong feasibility to increase energy efficiency and to prolong the lifetime of the MS. In this article, we present a complete architecture and an implementation for a decentralized positioning system. Furthermore, we introduce a technique for the synchronization of the observed magnetic field on the MS with the artificially-generated magnetic field from the coils. Based on real-time clocks (RTCs) and a preemptive operating system, this method allows a stand-alone control of the coils and a proper assignment of the measured magnetic fields on the MS. A stand-alone control and synchronization of the coils and the MS have an exceptional potential to implement a positioning system without the need for wired or wireless communication and enable a deployment of applications for rescue scenarios, like localization of miners or firefighters. PMID:26690145

Towards a Decentralized Magnetic Indoor Positioning System.

PubMed

Kasmi, Zakaria; Norrdine, Abdelmoumen; Blankenbach, Jörg

2015-12-04

Decentralized magnetic indoor localization is a sophisticated method for processing sampled magnetic data directly on a mobile station (MS), thereby decreasing or even avoiding the need for communication with the base station. In contrast to central-oriented positioning systems, which transmit raw data to a base station, decentralized indoor localization pushes application-level knowledge into the MS. A decentralized position solution has thus a strong feasibility to increase energy efficiency and to prolong the lifetime of the MS. In this article, we present a complete architecture and an implementation for a decentralized positioning system. Furthermore, we introduce a technique for the synchronization of the observed magnetic field on the MS with the artificially-generated magnetic field from the coils. Based on real-time clocks (RTCs) and a preemptive operating system, this method allows a stand-alone control of the coils and a proper assignment of the measured magnetic fields on the MS. A stand-alone control and synchronization of the coils and the MS have an exceptional potential to implement a positioning system without the need for wired or wireless communication and enable a deployment of applications for rescue scenarios, like localization of miners or firefighters.

Interaction Metrics for Feedback Control of Sound Radiation from Stiffened Panels

NASA Technical Reports Server (NTRS)

Cabell, Randolph H.; Cox, David E.; Gibbs, Gary P.

2003-01-01

Interaction metrics developed for the process control industry are used to evaluate decentralized control of sound radiation from bays on an aircraft fuselage. The metrics are applied to experimentally measured frequency response data from a model of an aircraft fuselage. The purpose is to understand how coupling between multiple bays of the fuselage can destabilize or limit the performance of a decentralized active noise control system. The metrics quantitatively verify observations from a previous experiment, in which decentralized controllers performed worse than centralized controllers. The metrics do not appear to be useful for explaining control spillover which was observed in a previous experiment.

On Event-Triggered Adaptive Architectures for Decentralized and Distributed Control of Large-Scale Modular Systems

PubMed Central

Albattat, Ali; Gruenwald, Benjamin C.; Yucelen, Tansel

2016-01-01

The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically-interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance in the presence of system uncertainties that can result from modeling and degraded modes of operation of the modules and their interconnections between each other. In addition to the theoretical findings including rigorous system stability and the boundedness analysis of the closed-loop dynamical system, as well as the characterization of the effect of user-defined event-triggering thresholds and the design parameters of the proposed adaptive architectures on the overall system performance, an illustrative numerical example is further provided to demonstrate the efficacy of the proposed decentralized and distributed control approaches. PMID:27537894

On Event-Triggered Adaptive Architectures for Decentralized and Distributed Control of Large-Scale Modular Systems.

PubMed

Albattat, Ali; Gruenwald, Benjamin C; Yucelen, Tansel

2016-08-16

The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically-interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance in the presence of system uncertainties that can result from modeling and degraded modes of operation of the modules and their interconnections between each other. In addition to the theoretical findings including rigorous system stability and the boundedness analysis of the closed-loop dynamical system, as well as the characterization of the effect of user-defined event-triggering thresholds and the design parameters of the proposed adaptive architectures on the overall system performance, an illustrative numerical example is further provided to demonstrate the efficacy of the proposed decentralized and distributed control approaches.

Decentralized DC Microgrid Monitoring and Optimization via Primary Control Perturbations

NASA Astrophysics Data System (ADS)

Angjelichinoski, Marko; Scaglione, Anna; Popovski, Petar; Stefanovic, Cedomir

2018-06-01

We treat the emerging power systems with direct current (DC) MicroGrids, characterized with high penetration of power electronic converters. We rely on the power electronics to propose a decentralized solution for autonomous learning of and adaptation to the operating conditions of the DC Mirogrids; the goal is to eliminate the need to rely on an external communication system for such purpose. The solution works within the primary droop control loops and uses only local bus voltage measurements. Each controller is able to estimate (i) the generation capacities of power sources, (ii) the load demands, and (iii) the conductances of the distribution lines. To define a well-conditioned estimation problem, we employ decentralized strategy where the primary droop controllers temporarily switch between operating points in a coordinated manner, following amplitude-modulated training sequences. We study the use of the estimator in a decentralized solution of the Optimal Economic Dispatch problem. The evaluations confirm the usefulness of the proposed solution for autonomous MicroGrid operation.

A survey of decentralized control techniques for large space structures

NASA Technical Reports Server (NTRS)

Lindner, D. K.; Reichard, K.

1987-01-01

Preliminary results on the design of decentralized controllers for the COFS I Mast are reported. A nine mode finite element model is used along with second order model of the actuators. It is shown that without actuator dynamics, the system is stable with collocated rate feedback and has acceptable performace. However, when actuator dynamics are included, the system is unstable.

Decentralized control of the COFS-I Mast using linear dc motors

NASA Technical Reports Server (NTRS)

Lindner, Douglas K.; Celano, Tom; Ide, Eric

1989-01-01

Consideration is given to a decentralized control design for vibration suppression in the COFS-I Mast using linear dc motors for actuators. The decentralized control design is based results from power systems using root locus techniques that are not well known. The approach is effective because the loop gain is low due to low actuator authority. The frequency-dependent nonlinearities of the actuator are taken into account. Because of the tendency of the transients to saturate the the stroke length of the actuator, its effectiveness is limited.

Event-triggered decentralized adaptive fault-tolerant control of uncertain interconnected nonlinear systems with actuator failures.

PubMed

Choi, Yun Ho; Yoo, Sung Jin

2018-06-01

This paper investigates the event-triggered decentralized adaptive tracking problem of a class of uncertain interconnected nonlinear systems with unexpected actuator failures. It is assumed that local control signals are transmitted to local actuators with time-varying faults whenever predefined conditions for triggering events are satisfied. Compared with the existing control-input-based event-triggering strategy for adaptive control of uncertain nonlinear systems, the aim of this paper is to propose a tracking-error-based event-triggering strategy in the decentralized adaptive fault-tolerant tracking framework. The proposed approach can relax drastic changes in control inputs caused by actuator faults in the existing triggering strategy. The stability of the proposed event-triggering control system is analyzed in the Lyapunov sense. Finally, simulation comparisons of the proposed and existing approaches are provided to show the effectiveness of the proposed theoretical result in the presence of actuator faults. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Stability of Fiber Optic Networked Decentralized Distributed Engine Control Under Time Delays

DTIC Science & Technology

2009-08-01

Nomenclature FADEC = Full Authority Digital Engine Control D2FADEC = Decentralized Distributed Full Authority Digital Engine Control DEC...Corporation (IFOS), bm@ifos.com. I American Institute of Aeronautics and Astronautics 2 II. Distributed Engine Control Systems FADEC Based on...of Full Authority Digital Engine Control ( FADEC ) are distributed at the component level. Each sensor/actuator is to be replaced by a smart sensor

Market-oriented Programming Using Small-world Networks for Controlling Building Environments

NASA Astrophysics Data System (ADS)

Shigei, Noritaka; Miyajima, Hiromi; Osako, Tsukasa

The market model, which is one of the economic activity models, is modeled as an agent system, and applying the model to the resource allocation problem has been studied. For air conditioning control of building, which is one of the resource allocation problems, an effective method based on the agent system using auction has been proposed for traditional PID controller. On the other hand, it has been considered that this method is performed by decentralized control. However, its decentralization is not perfect, and its performace is not enough. In this paper, firstly, we propose a perfectly decentralized agent model and show its performance. Secondly, in order to improve the model, we propose the agent model based on small-world model. The effectiveness of the proposed model is shown by simulation.

Outdoor flocking of quadcopter drones with decentralized model predictive control.

PubMed

Yuan, Quan; Zhan, Jingyuan; Li, Xiang

2017-11-01

In this paper, we present a multi-drone system featured with a decentralized model predictive control (DMPC) flocking algorithm. The drones gather localized information from neighbors and update their velocities using the DMPC flocking algorithm. In the multi-drone system, data packages are transmitted through XBee ® wireless modules in broadcast mode, yielding such an anonymous and decentralized system where all the calculations and controls are completed on an onboard minicomputer of each drone. Each drone is a double-layered agent system with the coordination layer running multi-drone flocking algorithms and the flight control layer navigating the drone, and the final formation of the flock relies on both the communication range and the desired inter-drone distance. We give both numerical simulations and field tests with a flock of five drones, showing that the DMPC flocking algorithm performs well on the presented multi-drone system in both the convergence rate and the ability of tracking a desired path. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Experimental Verification of Fully Decentralized Control Inspired by Plasmodium of True Slime Mold

NASA Astrophysics Data System (ADS)

Umedachi, Takuya; Takeda, Koichi; Nakagaki, Toshiyuki; Kobayashi, Ryo; Ishiguro, Akio

This paper presents a fully decentralized control inspired by plasmodium of true slime mold and its validity using a soft-bodied amoeboid robot. The notable features of this paper are twofold: (1) the robot has truly soft and deformable body stemming from real-time tunable springs and a balloon, the former is utilized as an outer skin of the body and the latter serves as protoplasm; and (2) a fully decentralized control using coupled oscillators with completely local sensory feedback mechanism is realized by exploiting the long-distance physical interaction between the body parts induced by the law of conservation of protoplasmic mass. Experimental results show that this robot exhibits truly supple locomotion without relying on any hierarchical structure. The results obtained are expected to shed new light on design scheme for autonomous decentralized control system.

Asymptotically suboptimal control of weakly interconnected dynamical systems

NASA Astrophysics Data System (ADS)

Dmitruk, N. M.; Kalinin, A. I.

2016-10-01

Optimal control problems for a group of systems with weak dynamical interconnections between its constituent subsystems are considered. A method for decentralized control is proposed which distributes the control actions between several controllers calculating in real time control inputs only for theirs subsystems based on the solution of the local optimal control problem. The local problem is solved by asymptotic methods that employ the representation of the weak interconnection by a small parameter. Combination of decentralized control and asymptotic methods allows to significantly reduce the dimension of the problems that have to be solved in the course of the control process.

Optimal decentralized feedback control for a truss structure

NASA Technical Reports Server (NTRS)

Cagle, A.; Ozguner, U.

1989-01-01

One approach to the decentralized control of large flexible space structures involves the design of controllers for the substructures of large systems and their subsequent application to the entire coupled system. This approach is presently developed for the case of active vibration damping on an experimental large struss structure. The isolated boundary loading method is used to define component models by FEM; component controllers are designed using an interlocking control concept which minimizes the motion of the boundary nodes, thereby reducing the exchange of mechanical disturbances among components.

Integrated control strategy for autonomous decentralized conveyance systems based on distributed MEMS arrays

NASA Astrophysics Data System (ADS)

Zhou, Lingfei; Chapuis, Yves-Andre; Blonde, Jean-Philippe; Bervillier, Herve; Fukuta, Yamato; Fujita, Hiroyuki

2004-07-01

In this paper, the authors proposed to study a model and a control strategy of a two-dimensional conveyance system based on the principles of the Autonomous Decentralized Microsystems (ADM). The microconveyance system is based on distributed cooperative MEMS actuators which can produce a force field onto the surface of the device to grip and move a micro-object. The modeling approach proposed here is based on a simple model of a microconveyance system which is represented by a 5 x 5 matrix of cells. Each cell is consisted of a microactuator, a microsensor, and a microprocessor to provide actuation, autonomy and decentralized intelligence to the cell. Thus, each cell is able to identify a micro-object crossing on it and to decide by oneself the appropriate control strategy to convey the micro-object to its destination target. The control strategy could be established through five simple decision rules that the cell itself has to respect at each calculate cycle time. Simulation and FPGA implementation results are given in the end of the paper in order to validate model and control approach of the microconveyance system.

Decentralized adaptive control of interconnected nonlinear systems with unknown control directions.

PubMed

Huang, Jiangshuai; Wang, Qing-Guo

2018-03-01

In this paper, we propose a decentralized adaptive control scheme for a class of interconnected strict-feedback nonlinear systems without a priori knowledge of subsystems' control directions. To address this problem, a novel Nussbaum-type function is proposed and a key theorem is drawn which involves quantifying the interconnections of multiple Nussbaum-type functions of the subsystems with different control directions in a single inequality. Global stability of the closed-loop system and asymptotic stabilization of subsystems' output are proved and a simulation example is given to illustrate the effectiveness of the proposed control scheme. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Polya's bees: A model of decentralized decision-making.

PubMed

Golman, Russell; Hagmann, David; Miller, John H

2015-09-01

How do social systems make decisions with no single individual in control? We observe that a variety of natural systems, including colonies of ants and bees and perhaps even neurons in the human brain, make decentralized decisions using common processes involving information search with positive feedback and consensus choice through quorum sensing. We model this process with an urn scheme that runs until hitting a threshold, and we characterize an inherent tradeoff between the speed and the accuracy of a decision. The proposed common mechanism provides a robust and effective means by which a decentralized system can navigate the speed-accuracy tradeoff and make reasonably good, quick decisions in a variety of environments. Additionally, consensus choice exhibits systemic risk aversion even while individuals are idiosyncratically risk-neutral. This too is adaptive. The model illustrates how natural systems make decentralized decisions, illuminating a mechanism that engineers of social and artificial systems could imitate.

Polya’s bees: A model of decentralized decision-making

PubMed Central

Golman, Russell; Hagmann, David; Miller, John H.

2015-01-01

How do social systems make decisions with no single individual in control? We observe that a variety of natural systems, including colonies of ants and bees and perhaps even neurons in the human brain, make decentralized decisions using common processes involving information search with positive feedback and consensus choice through quorum sensing. We model this process with an urn scheme that runs until hitting a threshold, and we characterize an inherent tradeoff between the speed and the accuracy of a decision. The proposed common mechanism provides a robust and effective means by which a decentralized system can navigate the speed-accuracy tradeoff and make reasonably good, quick decisions in a variety of environments. Additionally, consensus choice exhibits systemic risk aversion even while individuals are idiosyncratically risk-neutral. This too is adaptive. The model illustrates how natural systems make decentralized decisions, illuminating a mechanism that engineers of social and artificial systems could imitate. PMID:26601255

On the interaction structure of linear multi-input feedback control systems. M.S. Thesis; [problem solving, lattices (mathematics)

NASA Technical Reports Server (NTRS)

Wong, P. K.

1975-01-01

The closely-related problems of designing reliable feedback stabilization strategy and coordinating decentralized feedbacks are considered. Two approaches are taken. A geometric characterization of the structure of control interaction (and its dual) was first attempted and a concept of structural homomorphism developed based on the idea of 'similarity' of interaction pattern. The idea of finding classes of individual feedback maps that do not 'interfere' with the stabilizing action of each other was developed by identifying the structural properties of nondestabilizing and LQ-optimal feedback maps. Some known stability properties of LQ-feedback were generalized and some partial solutions were provided to the reliable stabilization and decentralized feedback coordination problems. A concept of coordination parametrization was introduced, and a scheme for classifying different modes of decentralization (information, control law computation, on-line control implementation) in control systems was developed.

Finite-time resilient decentralized control for interconnected impulsive switched systems with neutral delay.

PubMed

Ren, Hangli; Zong, Guangdeng; Hou, Linlin; Yang, Yi

2017-03-01

This paper is concerned with the problem of finite-time control for a class of interconnected impulsive switched systems with neutral delay in which the time-varying delay appears in both the state and the state derivative. The concepts of finite-time boundedness and finite-time stability are respectively extended to interconnected impulsive switched systems with neutral delay for the first time. By applying the average dwell time method, sufficient conditions are first derived to cope with the problem of finite-time boundedness and finite-time stability for interconnected impulsive switched systems with neutral delay. In addition, the purpose of finite-time resilient decentralized control is to construct a resilient decentralized state-feedback controller such that the closed-loop system is finite-time bounded and finite-time stable. All the conditions are formulated in terms of linear matrix inequalities to ensure finite-time boundedness and finite-time stability of the given system. Finally, an example is presented to illustrate the effectiveness of the proposed approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Substructural controller synthesis

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Craig, Roy R., Jr.

1989-01-01

A decentralized design procedure which combines substructural synthesis, model reduction, decentralized controller design, subcontroller synthesis, and controller reduction is proposed for the control design of flexible structures. The structure to be controlled is decomposed into several substructures, which are modeled by component mode synthesis methods. For each substructure, a subcontroller is designed by using the linear quadratic optimal control theory. Then, a controller synthesis scheme called Substructural Controller Synthesis (SCS) is used to assemble the subcontrollers into a system controller, which is to be used to control the whole structure.

Integration of a Decentralized Linear-Quadratic-Gaussian Control into GSFC's Universal 3-D Autonomous Formation Flying Algorithm

NASA Technical Reports Server (NTRS)

Folta, David C.; Carpenter, J. Russell

1999-01-01

A decentralized control is investigated for applicability to the autonomous formation flying control algorithm developed by GSFC for the New Millenium Program Earth Observer-1 (EO-1) mission. This decentralized framework has the following characteristics: The approach is non-hierarchical, and coordination by a central supervisor is not required; Detected failures degrade the system performance gracefully; Each node in the decentralized network processes only its own measurement data, in parallel with the other nodes; Although the total computational burden over the entire network is greater than it would be for a single, centralized controller, fewer computations are required locally at each node; Requirements for data transmission between nodes are limited to only the dimension of the control vector, at the cost of maintaining a local additional data vector. The data vector compresses all past measurement history from all the nodes into a single vector of the dimension of the state; and The approach is optimal with respect to standard cost functions. The current approach is valid for linear time-invariant systems only. Similar to the GSFC formation flying algorithm, the extension to linear LQG time-varying systems requires that each node propagate its filter covariance forward (navigation) and controller Riccati matrix backward (guidance) at each time step. Extension of the GSFC algorithm to non-linear systems can also be accomplished via linearization about a reference trajectory in the standard fashion, or linearization about the current state estimate as with the extended Kalman filter. To investigate the feasibility of the decentralized integration with the GSFC algorithm, an existing centralized LQG design for a single spacecraft orbit control problem is adapted to the decentralized framework while using the GSFC algorithm's state transition matrices and framework. The existing GSFC design uses both reference trajectories of each spacecraft in formation and by appropriate choice of coordinates and simplified measurement modeling is formulated as a linear time-invariant system. Results for improvements to the GSFC algorithm and a multiple satellite formation will be addressed. The goal of this investigation is to progressively relax the assumptions that result in linear time-invariance, ultimately to the point of linearization of the non-linear dynamics about the current state estimate as in the extended Kalman filter. An assessment will then be made about the feasibility of the decentralized approach to the realistic formation flying application of the EO-1/Landsat 7 formation flying experiment.

Decentralized hierarchical partitioning of centralized integrated controllers. [for flight propulsion in STOVLs

NASA Technical Reports Server (NTRS)

Schmidt, Phillip; Garg, Sanjay

1991-01-01

A framework for a decentralized hierarchical controller partitioning structure is developed. This structure allows for the design of separate airframe and propulsion controllers which, when assembled, will meet the overall design criterion for the integrated airframe/propulsion system. An algorithm based on parameter optimization of the state-space representation for the subsystem controllers is described. The algorithm is currently being applied to an integrated flight propulsion control design example.

Decentralized adaptive neural control for high-order interconnected stochastic nonlinear time-delay systems with unknown system dynamics.

PubMed

Si, Wenjie; Dong, Xunde; Yang, Feifei

2018-03-01

This paper is concerned with the problem of decentralized adaptive backstepping state-feedback control for uncertain high-order large-scale stochastic nonlinear time-delay systems. For the control design of high-order large-scale nonlinear systems, only one adaptive parameter is constructed to overcome the over-parameterization, and neural networks are employed to cope with the difficulties raised by completely unknown system dynamics and stochastic disturbances. And then, the appropriate Lyapunov-Krasovskii functional and the property of hyperbolic tangent functions are used to deal with the unknown unmatched time-delay interactions of high-order large-scale systems for the first time. At last, on the basis of Lyapunov stability theory, the decentralized adaptive neural controller was developed, and it decreases the number of learning parameters. The actual controller can be designed so as to ensure that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB) and the tracking error converges in the small neighborhood of zero. The simulation example is used to further show the validity of the design method. Copyright © 2018 Elsevier Ltd. All rights reserved.

Intelligent Decentralized Control In Large Distributed Computer Systems

DTIC Science & Technology

1988-04-01

decentralized. The goal is to find a way for the agents to coordinate their actions to maximize some index of system performance. (Our main...shown in Figure 4.13. The controller observes the environ- ment through sensors, and then may issue a command (i.e., take action ) to affect the...the Hypothesis Generator and the Belief Manager, and finally actions are issued by the Action Generator, the Experiment Generator, or the Reflex

A discrete decentralized variable structure robotic controller

NASA Technical Reports Server (NTRS)

Tumeh, Zuheir S.

1989-01-01

A decentralized trajectory controller for robotic manipulators is designed and tested using a multiprocessor architecture and a PUMA 560 robot arm. The controller is made up of a nominal model-based component and a correction component based on a variable structure suction control approach. The second control component is designed using bounds on the difference between the used and actual values of the model parameters. Since the continuous manipulator system is digitally controlled along a trajectory, a discretized equivalent model of the manipulator is used to derive the controller. The motivation for decentralized control is that the derived algorithms can be executed in parallel using a distributed, relatively inexpensive, architecture where each joint is assigned a microprocessor. Nonlinear interaction and coupling between joints is treated as a disturbance torque that is estimated and compensated for.

Lost in Translation: Ever Changing and Competing Purposes for National Examinations in the Czech Republic

ERIC Educational Resources Information Center

Greger, D.; Kifer, E.

2012-01-01

In reaction to central control of schooling by the Soviet Union, the Czech Republic countered with what some say was the most decentralized system in Europe. While the political move to democracy was extraordinarily successful, there were numerous governments between 1989 and the present. The combination of the decentralized control of schooling…

Decentralized-feedback pole placement of linear systems

NASA Technical Reports Server (NTRS)

Wang, X.; Martin, C. F.; Gilliam, D.; Byrnes, C. I.

1992-01-01

A projectile product spaces model is used to analyze decentralized systems. The degree of the pole placement map is computed. The conditions under which the degree is odd are also given. Twin lift systems are studied. It is proved that the poles of a twin lift system can be assigned to any values by local static and local dynamic feedback laws if and only if the system is jointly controllable.

Decentralized coordinated control of elastic web winding systems without tension sensor.

PubMed

Hou, Hailiang; Nian, Xiaohong; Chen, Jie; Xiao, Dengfeng

2018-06-26

In elastic web winding systems, precise regulation of web tension in each span is critical to ensure final product quality, and to achieve low cost by reducing the occurrence of web break or fold. Generally, web winding systems use load cells or swing rolls as tension sensors, which add cost, reduce system reliability and increase the difficulty of control. In this paper, a decentralized coordinated control scheme with tension observers is designed for a three-motor web-winding system. First, two tension observers are proposed to estimate the unwinding and winding tension. The designed observers consider the essential dynamic, radius, and inertial variation effects and only require the modest computational effort. Then, using the estimated tensions as feedback signals, a robust decentralized coordinated controller is adopted to reduce the interaction between subsystems. Asymptotic stabilities of the observer error dynamics and the closed-loop winding systems are demonstrated via Lyapunov stability theory. The observer gains and the controller gains can be obtained by solving matrix inequalities. Finally, some simulations and experiments are performed on a paper winding setup to test the performance of the designed observers and the observer-base DCC method, respectively. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Decentralized automatic generation control of interconnected power systems incorporating asynchronous tie-lines.

PubMed

Ibraheem; Hasan, Naimul; Hussein, Arkan Ahmed

2014-01-01

This Paper presents the design of decentralized automatic generation controller for an interconnected power system using PID, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The designed controllers are tested on identical two-area interconnected power systems consisting of thermal power plants. The area interconnections between two areas are considered as (i) AC tie-line only (ii) Asynchronous tie-line. The dynamic response analysis is carried out for 1% load perturbation. The performance of the intelligent controllers based on GA and PSO has been compared with the conventional PID controller. The investigations of the system dynamic responses reveal that PSO has the better dynamic response result as compared with PID and GA controller for both type of area interconnection.

Decentralized Control of Sound Radiation using a High-Authority/Low-Authority Control Strategy with Anisotropic Actuators

NASA Technical Reports Server (NTRS)

Schiller, Noah H.; Cabell, Randolph H.; Fuller, Chris R.

2008-01-01

This paper describes a combined control strategy designed to reduce sound radiation from stiffened aircraft-style panels. The control architecture uses robust active damping in addition to high-authority linear quadratic Gaussian (LQG) control. Active damping is achieved using direct velocity feedback with triangularly shaped anisotropic actuators and point velocity sensors. While active damping is simple and robust, stability is guaranteed at the expense of performance. Therefore the approach is often referred to as low-authority control. In contrast, LQG control strategies can achieve substantial reductions in sound radiation. Unfortunately, the unmodeled interaction between neighboring control units can destabilize decentralized control systems. Numerical simulations show that combining active damping and decentralized LQG control can be beneficial. In particular, augmenting the in-bandwidth damping supplements the performance of the LQG control strategy and reduces the destabilizing interaction between neighboring control units.

Decentralized control of large flexible structures by joint decoupling

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Juang, Jer-Nan

1992-01-01

A decentralized control design method is presented for large complex flexible structures by using the idea of joint decoupling. The derivation is based on a coupled substructure state-space model, which is obtained from enforcing conditions of interface compatibility and equilibrium to the substructure state-space models. It is shown that by restricting the control law to be localized state feedback and by setting the joint actuator input commands to decouple joint 'degrees of freedom' (dof) from interior dof, the global structure control design problem can be decomposed into several substructure control design problems. The substructure control gains and substructure observers are designed based on modified substructure state-space models. The controllers produced by the proposed method can operate successfully at the individual substructure level as well as at the global structure level. Therefore, not only control design but also control implementation is decentralized. Stability and performance requirement of the closed-loop system can be achieved by using any existing state feedback control design method. A two-component mass-spring damper system and a three-truss structure are used as examples to demonstrate the proposed method.

A Decentralized Event-Triggered Dissipative Control Scheme for Systems With Multiple Sensors to Sample the System Outputs.

PubMed

Zhang, Xian-Ming; Han, Qing-Long

2016-12-01

This paper is concerned with decentralized event-triggered dissipative control for systems with the entries of the system outputs having different physical properties. Depending on these different physical properties, the entries of the system outputs are grouped into multiple nodes. A number of sensors are used to sample the signals from different nodes. A decentralized event-triggering scheme is introduced to select those necessary sampled-data packets to be transmitted so that communication resources can be saved significantly while preserving the prescribed closed-loop performance. First, in order to organize the decentralized data packets transmitted from the sensor nodes, a data packet processor (DPP) is used to generate a new signal to be held by the zero-order-hold once the signal stored by the DPP is updated at some time instant. Second, under the mechanism of the DPP, the resulting closed-loop system is modeled as a linear system with an interval time-varying delay. A sufficient condition is derived such that the closed-loop system is asymptotically stable and strictly (Q 0 ,S 0 ,R 0 ) -dissipative, where Q 0 ,S 0 , and R 0 are real matrices of appropriate dimensions with Q 0 and R 0 symmetric. Third, suitable output-based controllers can be designed based on solutions to a set of a linear matrix inequality. Finally, two examples are given to demonstrate the effectiveness of the proposed method.

Controllability analysis and decentralized control of a wet limestone flue gas desulfurization plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perales, A.L.V.; Ortiz, F.J.G.; Ollero, P.

2008-12-15

Presently, decentralized feedback control is the only control strategy used in wet limestone flue gas desulfurization (WLFGD) plants. Proper tuning of this control strategy is becoming an important issue in WLFGD plants because more stringent SO{sub 2} regulations have come into force recently. Controllability analysis is a highly valuable tool for proper design of control systems, but it has not been applied to WLFGD plants so far. In this paper a decentralized control strategy is designed and applied to a WLFGD pilot plant taking into account the conclusions of a controllability analysis. The results reveal that good SO{sub 2} controlmore » in WLFGD plants can be achieved mainly because the main disturbance of the process is well-aligned with the plant and interactions between control loops are beneficial to SO{sub 2} control.« less

Decentralized PID controller for TITO systems using characteristic ratio assignment with an experimental application.

PubMed

Hajare, V D; Patre, B M

2015-11-01

This paper presents a decentralized PID controller design method for two input two output (TITO) systems with time delay using characteristic ratio assignment (CRA) method. The ability of CRA method to design controller for desired transient response has been explored for TITO systems. The design methodology uses an ideal decoupler to reduce the interaction. Each decoupled subsystem is reduced to first order plus dead time (FOPDT) model to design independent diagonal controllers. Based on specified overshoot and settling time, the controller parameters are computed using CRA method. To verify performance of the proposed controller, two benchmark simulation examples are presented. To demonstrate applicability of the proposed controller, experimentation is performed on real life interacting coupled tank level system. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Neural joint control for Space Shuttle Remote Manipulator System

NASA Technical Reports Server (NTRS)

Atkins, Mark A.; Cox, Chadwick J.; Lothers, Michael D.; Pap, Robert M.; Thomas, Charles R.

1992-01-01

Neural networks are being used to control a robot arm in a telerobotic operation. The concept uses neural networks for both joint and inverse kinematics in a robotic control application. An upper level neural network is trained to learn inverse kinematic mappings. The output, a trajectory, is then fed to the Decentralized Adaptive Joint Controllers. This neural network implementation has shown that the controlled arm recovers from unexpected payload changes while following the reference trajectory. The neural network-based decentralized joint controller is faster, more robust and efficient than conventional approaches. Implementations of this architecture are discussed that would relax assumptions about dynamics, obstacles, and heavy loads. This system is being developed to use with the Space Shuttle Remote Manipulator System.

Nitrogen Control Through Decentralized Wastewater Treatment: Process Performance and Alternative Management Strategies

EPA Science Inventory

Decentralized or onsite wastewater treatment (OWT) systems have long been implicated in being a major source of N inputs to surface and ground waters and numerous regulatory bodies have promulgated strict total N (TN) effluent standards in N-sensitive areas. These standards, howe...

Decentralized control experiments on NASA's flexible grid

NASA Technical Reports Server (NTRS)

Ozguner, U.; Yurkowich, S.; Martin, J., III; Al-Abbass, F.

1986-01-01

Methods arising from the area of decentralized control are emerging for analysis and control synthesis for large flexible structures. In this paper the control strategy involves a decentralized model reference adaptive approach using a variable structure control. Local models are formulated based on desired damping and response time in a model-following scheme for various modal configurations. Variable structure controllers are then designed employing co-located angular rate and position feedback. In this scheme local control forces the system to move on a local sliding mode in some local error space. An important feature of this approach is that the local subsystem is made insensitive to dynamical interactions with other subsystems once the sliding surface is reached. Experiments based on the above have been performed for NASA's flexible grid experimental apparatus. The grid is designed to admit appreciable low-frequency structural dynamics, and allows for implementation of distributed computing components, inertial sensors, and actuation devices. A finite-element analysis of the grid provides the model for control system design and simulation; results of several simulations are reported on here, and a discussion of application experiments on the apparatus is presented.

Autonomous, Decentralized Grid Architecture: Prosumer-Based Distributed Autonomous Cyber-Physical Architecture for Ultra-Reliable Green Electricity Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2012-01-11

GENI Project: Georgia Tech is developing a decentralized, autonomous, internet-like control architecture and control software system for the electric power grid. Georgia Tech’s new architecture is based on the emerging concept of electricity prosumers—economically motivated actors that can produce, consume, or store electricity. Under Georgia Tech’s architecture, all of the actors in an energy system are empowered to offer associated energy services based on their capabilities. The actors achieve their sustainability, efficiency, reliability, and economic objectives, while contributing to system-wide reliability and efficiency goals. This is in marked contrast to the current one-way, centralized control paradigm.

Decentralized Adaptive Neural Output-Feedback DSC for Switched Large-Scale Nonlinear Systems.

PubMed

Lijun Long; Jun Zhao

2017-04-01

In this paper, for a class of switched large-scale uncertain nonlinear systems with unknown control coefficients and unmeasurable states, a switched-dynamic-surface-based decentralized adaptive neural output-feedback control approach is developed. The approach proposed extends the classical dynamic surface control (DSC) technique for nonswitched version to switched version by designing switched first-order filters, which overcomes the problem of multiple "explosion of complexity." Also, a dual common coordinates transformation of all subsystems is exploited to avoid individual coordinate transformations for subsystems that are required when applying the backstepping recursive design scheme. Nussbaum-type functions are utilized to handle the unknown control coefficients, and a switched neural network observer is constructed to estimate the unmeasurable states. Combining with the average dwell time method and backstepping and the DSC technique, decentralized adaptive neural controllers of subsystems are explicitly designed. It is proved that the approach provided can guarantee the semiglobal uniformly ultimately boundedness for all the signals in the closed-loop system under a class of switching signals with average dwell time, and the tracking errors to a small neighborhood of the origin. A two inverted pendulums system is provided to demonstrate the effectiveness of the method proposed.

Robust decentralized hybrid adaptive output feedback fuzzy control for a class of large-scale MIMO nonlinear systems and its application to AHS.

PubMed

Huang, Yi-Shao; Liu, Wel-Ping; Wu, Min; Wang, Zheng-Wu

2014-09-01

This paper presents a novel observer-based decentralized hybrid adaptive fuzzy control scheme for a class of large-scale continuous-time multiple-input multiple-output (MIMO) uncertain nonlinear systems whose state variables are unmeasurable. The scheme integrates fuzzy logic systems, state observers, and strictly positive real conditions to deal with three issues in the control of a large-scale MIMO uncertain nonlinear system: algorithm design, controller singularity, and transient response. Then, the design of the hybrid adaptive fuzzy controller is extended to address a general large-scale uncertain nonlinear system. It is shown that the resultant closed-loop large-scale system keeps asymptotically stable and the tracking error converges to zero. The better characteristics of our scheme are demonstrated by simulations. Copyright © 2014. Published by Elsevier Ltd.

Centralized and Decentralized Control for Demand Response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Shuai; Samaan, Nader A.; Diao, Ruisheng

2011-04-29

Demand response has been recognized as an essential element of the smart grid. Frequency response, regulation and contingency reserve functions performed traditionally by generation resources are now starting to involve demand side resources. Additional benefits from demand response include peak reduction and load shifting, which will defer new infrastructure investment and improve generator operation efficiency. Technical approaches designed to realize these functionalities can be categorized into centralized control and decentralized control, depending on where the response decision is made. This paper discusses these two control philosophies and compares their relative advantages and disadvantages in terms of delay time, predictability, complexity,more » and reliability. A distribution system model with detailed household loads and controls is built to demonstrate the characteristics of the two approaches. The conclusion is that the promptness and reliability of decentralized control should be combined with the predictability and simplicity of centralized control to achieve the best performance of the smart grid.« less

Application of Transfer Matrix Approach to Modeling and Decentralized Control of Lattice-Based Structures

NASA Technical Reports Server (NTRS)

Cramer, Nick; Swei, Sean Shan-Min; Cheung, Kenny; Teodorescu, Mircea

2015-01-01

This paper presents a modeling and control of aerostructure developed by lattice-based cellular materials/components. The proposed aerostructure concept leverages a building block strategy for lattice-based components which provide great adaptability to varying ight scenarios, the needs of which are essential for in- ight wing shaping control. A decentralized structural control design is proposed that utilizes discrete-time lumped mass transfer matrix method (DT-LM-TMM). The objective is to develop an e ective reduced order model through DT-LM-TMM that can be used to design a decentralized controller for the structural control of a wing. The proposed approach developed in this paper shows that, as far as the performance of overall structural system is concerned, the reduced order model can be as e ective as the full order model in designing an optimal stabilizing controller.

On decentralized design: Rationale, dynamics, and effects on decision-making

NASA Astrophysics Data System (ADS)

Chanron, Vincent

The focus of this dissertation is the design of complex systems, including engineering systems such as cars, airplanes, and satellites. Companies who design these systems are under constant pressure to design better products that meet customer expectations, and competition forces them to develop them faster. One of the responses of the industry to these conflicting challenges has been the decentralization of the design responsibilities. The current lack of understanding of the dynamics of decentralized design processes is the main motivation for this research, and places value on the descriptive base. It identifies the main reasons and the true benefits for companies to decentralize the design of their products. It also demonstrates the limitations of this approach by listing the relevant issues and problems created by the decentralization of decisions. Based on these observations, a game-theoretic approach to decentralized design is proposed to model the decisions made during the design process. The dynamics are modeled using mathematical formulations inspired from control theory. Building upon this formalism, the issue of convergence in decentralized design is analyzed: the equilibrium points of the design space are identified and convergent and divergent patterns are recognized. This rigorous investigation of the design process provides motivation and support for proposing new approaches to decentralized design problems. Two methods are developed, which aim at improving the design process in two ways: decreasing the product development time, and increasing the optimality of the final design. The frame of these methods are inspired by eigenstructure decomposition and set-based design, respectively. The value of the research detailed within this dissertation is in the proposed methods which are built upon the sound mathematical formalism developed. The contribution of this work is two fold: rigorous investigation of the design process, and practical support to decision-making in decentralized environments.

An informal paper on large-scale dynamic systems

NASA Technical Reports Server (NTRS)

Ho, Y. C.

1975-01-01

Large scale systems are defined as systems requiring more than one decision maker to control the system. Decentralized control and decomposition are discussed for large scale dynamic systems. Information and many-person decision problems are analyzed.

A Summary of Some Discrete-Event System Control Problems

NASA Astrophysics Data System (ADS)

Rudie, Karen

A summary of the area of control of discrete-event systems is given. In this research area, automata and formal language theory is used as a tool to model physical problems that arise in technological and industrial systems. The key ingredients to discrete-event control problems are a process that can be modeled by an automaton, events in that process that cannot be disabled or prevented from occurring, and a controlling agent that manipulates the events that can be disabled to guarantee that the process under control either generates all the strings in some prescribed language or as many strings as possible in some prescribed language. When multiple controlling agents act on a process, decentralized control problems arise. In decentralized discrete-event systems, it is presumed that the agents effecting control cannot each see all event occurrences. Partial observation leads to some problems that cannot be solved in polynomial time and some others that are not even decidable.

Linear decentralized systems with special structure. [for twin lift helicopters

NASA Technical Reports Server (NTRS)

Martin, C. F.

1982-01-01

Certain fundamental structures associated with linear systems having internal symmetries are outlined. It is shown that the theory of finite-dimensional algebras and their representations are closely related to such systems. It is also demonstrated that certain problems in the decentralized control of symmetric systems are equivalent to long-standing problems of linear systems theory. Even though the structure imposed arose in considering the problems of twin-lift helicopters, any large system composed of several identical intercoupled control systems can be modeled by a linear system that satisfies the constraints imposed. Internal symmetry can be exploited to yield new system-theoretic invariants and a better understanding of the way in which the underlying structure affects overall system performance.

Decentralized reinforcement-learning control and emergence of motion patterns

NASA Astrophysics Data System (ADS)

Svinin, Mikhail; Yamada, Kazuyaki; Okhura, Kazuhiro; Ueda, Kanji

1998-10-01

In this paper we propose a system for studying emergence of motion patterns in autonomous mobile robotic systems. The system implements an instance-based reinforcement learning control. Three spaces are of importance in formulation of the control scheme. They are the work space, the sensor space, and the action space. Important feature of our system is that all these spaces are assumed to be continuous. The core part of the system is a classifier system. Based on the sensory state space analysis, the control is decentralized and is specified at the lowest level of the control system. However, the local controllers are implicitly connected through the perceived environment information. Therefore, they constitute a dynamic environment with respect to each other. The proposed control scheme is tested under simulation for a mobile robot in a navigation task. It is shown that some patterns of global behavior--such as collision avoidance, wall-following, light-seeking--can emerge from the local controllers.

Decentralized authority, increased enforcement guide Mexico's environmental evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ranger, E.M.; Alonzo, A.L.

1994-01-01

Environmental regulation in Mexico is evolving into a decentralized system where local authorities assume responsibility for compliance. Articles 25, 27 and 73 of Mexico's constitution establish federal, state and municipal jurisdictions for environmental protection, and empower the federal congress to promulgate environmental legislation. An established federal and local environmental legislative and normative framework, along with increased enforcement, provide the country with a comprehensive regulatory system to prevent and control industrial pollution.

Decentralized control of human visceral leishmaniasis in endemic urban areas of Brazil: a literature review.

PubMed

Menon, Sonia S; Rossi, Rodolfo; Nshimyumukiza, Leon; Zinszer, Kate

2016-01-01

Human migration and concomitant HIV infections are likely to bring about major changes in the epidemiology of some parasitic infections in Brazil. Human visceral leishmaniasis (HVL) control is particularly fraught with intricacies. It is against a backdrop of decentralized health care that the complex HVL control initiatives are brought to bear. This comprehensive review aims to explore the obstacles facing decentralized HVL control in urban endemic areas in Brazil. A literature search was carried out in December 2015 by means of three databases: MEDLINE, Google Scholar, and Web of Science. Although there have been many strides that have been made in elucidating the eco-epidemiology of Leishmania infantum, which forms the underpinnings of the national control program, transmission risk factors for HVL are still insufficiently elucidated in urban settings. Decentralized HVL epidemiological surveillance and control for animal reservoirs and vectors may compromise sustainability. In addition, it may hamper timely human HVL case management. With the burgeoning of the HIV-HVL co-infection, the potential human transmission may be underestimated. HVL is a disease with focal transmission at a critical juncture, which warrants that the bottlenecks facing the control program within contexts of decentralized healthcare systems be taken into account. In addition, HIV-driven HVL epidemics may substantially increase the transmission potential of the human reservoir. Calculating the basic reproductive number to fine-tune interventions will have to take into consideration the specific socio-economic development context.

Peeling the Onion: Why Centralized Control / Decentralized Execution Works

DTIC Science & Technology

2014-04-01

March–April 2014 Air & Space Power Journal | 24 Feature Peeling the Onion Why Centralized Control / Decentralized Execution Works Lt Col Alan Docauer...DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Peeling the Onion : Why Centralized Control / Decentralized Execution Works 5a...Air & Space Power Journal | 25 Docauer Peeling the Onion Feature What Is Centralized Control / Decentralized Execution? Emerging in the aftermath of

Decentralized adaptive control of robot manipulators with robust stabilization design

NASA Technical Reports Server (NTRS)

Yuan, Bau-San; Book, Wayne J.

1988-01-01

Due to geometric nonlinearities and complex dynamics, a decentralized technique for adaptive control for multilink robot arms is attractive. Lyapunov-function theory for stability analysis provides an approach to robust stabilization. Each joint of the arm is treated as a component subsystem. The adaptive controller is made locally stable with servo signals including proportional and integral gains. This results in the bound on the dynamical interactions with other subsystems. A nonlinear controller which stabilizes the system with uniform boundedness is used to improve the robustness properties of the overall system. As a result, the robot tracks the reference trajectories with convergence. This strategy makes computation simple and therefore facilitates real-time implementation.

Autonomous Decentralized Voltage Profile Control of Super Distributed Energy System using Multi-agent Technology

NASA Astrophysics Data System (ADS)

Tsuji, Takao; Hara, Ryoichi; Oyama, Tsutomu; Yasuda, Keiichiro

A super distributed energy system is a future energy system in which the large part of its demand is fed by a huge number of distributed generators. At one time some nodes in the super distributed energy system behave as load, however, at other times they behave as generator - the characteristic of each node depends on the customers' decision. In such situation, it is very difficult to regulate voltage profile over the system due to the complexity of power flows. This paper proposes a novel control method of distributed generators that can achieve the autonomous decentralized voltage profile regulation by using multi-agent technology. The proposed multi-agent system employs two types of agent; a control agent and a mobile agent. Control agents generate or consume reactive power to regulate the voltage profile of neighboring nodes and mobile agents transmit the information necessary for VQ-control among the control agents. The proposed control method is tested through numerical simulations.

Decentralizing Education in Transition Societies: Case Studies from Central and Eastern Europe. WBI Learning Resources Series.

ERIC Educational Resources Information Center

Fiszbein, Ariel, Ed.

This book is about education system reform in Central and Eastern Europe, with emphasis on decentralization and management. In the past, local authorities served as implementation arms of the central ministry, while finance and decision-making were controlled by the central government, leaving local communities with little influence. New education…

Decentralized control of large-scale systems: Fixed modes, sensitivity and parametric robustness. Ph.D. Thesis - Universite Paul Sabatier, 1985

NASA Technical Reports Server (NTRS)

Tarras, A.

1987-01-01

The problem of stabilization/pole placement under structural constraints of large scale linear systems is discussed. The existence of a solution to this problem is expressed in terms of fixed modes. The aim is to provide a bibliographic survey of the available results concerning the fixed modes (characterization, elimination, control structure selection to avoid them, control design in their absence) and to present the author's contribution to this problem which can be summarized by the use of the mode sensitivity concept to detect or to avoid them, the use of vibrational control to stabilize them, and the addition of parametric robustness considerations to design an optimal decentralized robust control.

Disturbance decoupling, decentralized control and the Riccati equation

NASA Technical Reports Server (NTRS)

Garzia, M. R.; Loparo, K. A.; Martin, C. F.

1981-01-01

The disturbance decoupling and optimal decentralized control problems are looked at using identical mathematical techniques. A statement of the problems and the development of their solution approach is presented. Preliminary results are given for the optimal decentralized control problem.

A modified approach to controller partitioning

NASA Technical Reports Server (NTRS)

Garg, Sanjay; Veillette, Robert J.

1993-01-01

The idea of computing a decentralized control law for the integrated flight/propulsion control of an aircraft by partitioning a given centralized controller is investigated. An existing controller partitioning methodology is described, and a modified approach is proposed with the objective of simplifying the associated controller approximation problem. Under the existing approach, the decentralized control structure is a variable in the partitioning process; by contrast, the modified approach assumes that the structure is fixed a priori. Hence, the centralized controller design may take the decentralized control structure into account. Specifically, the centralized controller may be designed to include all the same inputs and outputs as the decentralized controller; then, the two controllers may be compared directly, simplifying the partitioning process considerably. Following the modified approach, a centralized controller is designed for an example aircraft mode. The design includes all the inputs and outputs to be used in a specified decentralized control structure. However, it is shown that the resulting centralized controller is not well suited for approximation by a decentralized controller of the given structure. The results indicate that it is not practical in general to cast the controller partitioning problem as a direct controller approximation problem.

Formation Flying With Decentralized Control in Libration Point Orbits

NASA Technical Reports Server (NTRS)

Folta, David; Carpenter, J. Russell; Wagner, Christoph

2000-01-01

A decentralized control framework is investigated for applicability of formation flying control in libration orbits. The decentralized approach, being non-hierarchical, processes only direct measurement data, in parallel with the other spacecraft. Control is accomplished via linearization about a reference libration orbit with standard control using a Linear Quadratic Regulator (LQR) or the GSFC control algorithm. Both are linearized about the current state estimate as with the extended Kalman filter. Based on this preliminary work, the decentralized approach appears to be feasible for upcoming libration missions using distributed spacecraft.

Does Decentralization Improve Health System Performance and Outcomes in Low- and Middle-Income Countries? A Systematic Review of Evidence From Quantitative Studies.

PubMed

Dwicaksono, Adenantera; Fox, Ashley M

2018-06-01

Policy Points: For more than 3 decades, international development agencies have advocated health system decentralization to improve health system performance in low- and middle-income countries. We found little rigorous evidence documenting the impact of decentralization processes on health system performance or outcomes in part due to challenges in measuring such far-reaching and multifaceted system-level changes. We propose a renewed research agenda that focuses on discrete definitions of decentralization and how institutional factors and mechanisms affect health system performance and outcomes within the general context of decentralized governance structures. Despite the widespread adoption of decentralization reforms as a means to improve public service delivery in developing countries since the 1980s, empirical evidence of the role of decentralization on health system improvement is still limited and inconclusive. This study reviewed studies published from 2000 to 2016 with adequate research designs to identify evidence on whether and how decentralization processes have impacted health systems. We conducted a systematic review of peer-reviewed journal articles from the public health and social science literature. We searched for articles within 9 databases using predefined search terms reflecting decentralization and health system constructs. Inclusion criteria were original research articles, low- and middle-income country settings, quantifiable outcome measures, and study designs that use comparisons or statistical adjustments. We excluded studies in high-income country settings and/or published in a non-English language. Sixteen studies met our prespecified inclusion and exclusion criteria and were grouped based on outcomes measured: health system inputs (n = 3), performance (n = 7), and health outcomes (n = 7). Numerous studies addressing conceptual issues related to decentralization but without any attempt at empirical estimation were excluded. Overall, we found mixed results regarding the effects of decentralization on health system indicators with seemingly beneficial effects on health system performance and health outcomes. Only 10 studies were considered to have relatively low risks of bias. This study reveals the limited empirical knowledge of the impact of decentralization on health system performance. Mixed empirical findings on the role of decentralization on health system performance and outcomes highlight the complexity of decentralization processes and their systemwide effects. Thus, we propose a renewed research agenda that focuses on discrete definitions of decentralization and how institutional factors and mechanisms affect health system performance and outcomes within the general context of decentralized governance structures. © 2018 Milbank Memorial Fund.

What supervisors want to know about decentralization.

PubMed

Boissoneau, R; Belton, P

1991-06-01

Many organizations in various industries have tended to move away from strict centralization, yet some centralization is still vital to top management. With 19 of the 22 executives interviewed favoring or implementing some form of decentralization, it is probable that traditionally centralized organizations will follow the trend and begin to decentralize their organizational structures. The incentives and advantages of decentralization are too attractive to ignore. Decentralization provides responsibility, clear objectives, accountability for results, and more efficient and effective decision making. However, one must remember that decentralization can be overextended and that centralization is still viable in certain functions. Finding the correct balance between control and autonomy is a key to decentralization. Too much control and too much autonomy are the primary reasons for decentralization failures. In today's changing, competitive environment, structures must be continuously redefined, with the goal of finding an optimal balance between centralization and decentralization. Organizations are cautioned not to seek out and install a single philosopher-king to impose unified direction, but to unify leadership goals, participation, style, and control to develop improved methods of making all responsible leaders of one mind about the organization's needs and goals.

Decentral Smart Grid Control

NASA Astrophysics Data System (ADS)

Schäfer, Benjamin; Matthiae, Moritz; Timme, Marc; Witthaut, Dirk

2015-01-01

Stable operation of complex flow and transportation networks requires balanced supply and demand. For the operation of electric power grids—due to their increasing fraction of renewable energy sources—a pressing challenge is to fit the fluctuations in decentralized supply to the distributed and temporally varying demands. To achieve this goal, common smart grid concepts suggest to collect consumer demand data, centrally evaluate them given current supply and send price information back to customers for them to decide about usage. Besides restrictions regarding cyber security, privacy protection and large required investments, it remains unclear how such central smart grid options guarantee overall stability. Here we propose a Decentral Smart Grid Control, where the price is directly linked to the local grid frequency at each customer. The grid frequency provides all necessary information about the current power balance such that it is sufficient to match supply and demand without the need for a centralized IT infrastructure. We analyze the performance and the dynamical stability of the power grid with such a control system. Our results suggest that the proposed Decentral Smart Grid Control is feasible independent of effective measurement delays, if frequencies are averaged over sufficiently large time intervals.

Adaptive Neural Networks Prescribed Performance Control Design for Switched Interconnected Uncertain Nonlinear Systems.

PubMed

Li, Yongming; Tong, Shaocheng

2017-06-28

In this paper, an adaptive neural networks (NNs)-based decentralized control scheme with the prescribed performance is proposed for uncertain switched nonstrict-feedback interconnected nonlinear systems. It is assumed that nonlinear interconnected terms and nonlinear functions of the concerned systems are unknown, and also the switching signals are unknown and arbitrary. A linear state estimator is constructed to solve the problem of unmeasured states. The NNs are employed to approximate unknown interconnected terms and nonlinear functions. A new output feedback decentralized control scheme is developed by using the adaptive backstepping design technique. The control design problem of nonlinear interconnected switched systems with unknown switching signals can be solved by the proposed scheme, and only a tuning parameter is needed for each subsystem. The proposed scheme can ensure that all variables of the control systems are semi-globally uniformly ultimately bounded and the tracking errors converge to a small residual set with the prescribed performance bound. The effectiveness of the proposed control approach is verified by some simulation results.

The snow system: A decentralized medical data processing system.

PubMed

Bellika, Johan Gustav; Henriksen, Torje Starbo; Yigzaw, Kassaye Yitbarek

2015-01-01

Systems for large-scale reuse of electronic health record data is claimed to have the potential to transform the current health care delivery system. In principle three alternative solutions for reuse exist: centralized, data warehouse, and decentralized solutions. This chapter focuses on the decentralized system alternative. Decentralized systems may be categorized into approaches that move data to enable computations or move computations to the where data is located to enable computations. We describe a system that moves computations to where the data is located. Only this kind of decentralized solution has the capabilities to become ideal systems for reuse as the decentralized alternative enables computation and reuse of electronic health record data without moving or exposing the information to outsiders. This chapter describes the Snow system, which is a decentralized medical data processing system, its components and how it has been used. It also describes the requirements this kind of systems need to support to become sustainable and successful in recruiting voluntary participation from health institutions.

Hybrid Control for Multi-Agent Systems in Complex Sensing Environments

DTIC Science & Technology

2012-02-28

controllers , the overall closed-loop system is time -varying but can potentially exhibit better stability and performance... system is time -varying and yet, once 4 feedback-interconnected with a suitable controller , it can potentially yield better stability and performance...resolution Sensing, Control and Switched Systems 13 4 Metric-Based Receding Horizon Control 14 5 Decentralized Control and Finite Wordlength Channels 15

Distributed Synchronization Control of Multiagent Systems With Unknown Nonlinearities.

PubMed

Su, Shize; Lin, Zongli; Garcia, Alfredo

2016-01-01

This paper revisits the distributed adaptive control problem for synchronization of multiagent systems where the dynamics of the agents are nonlinear, nonidentical, unknown, and subject to external disturbances. Two communication topologies, represented, respectively, by a fixed strongly-connected directed graph and by a switching connected undirected graph, are considered. Under both of these communication topologies, we use distributed neural networks to approximate the uncertain dynamics. Decentralized adaptive control protocols are then constructed to solve the cooperative tracker problem, the problem of synchronization of all follower agents to a leader agent. In particular, we show that, under the proposed decentralized control protocols, the synchronization errors are ultimately bounded, and their ultimate bounds can be reduced arbitrarily by choosing the control parameter appropriately. Simulation study verifies the effectiveness of our proposed protocols.

Decentralized adaptive control designs and microstrip antennas for smart structures

NASA Astrophysics Data System (ADS)

Khorrami, Farshad; Jain, Sandeep; Das, Nirod K.

1996-05-01

Smart structures lend themselves naturally to a decentralized control design framework, especially with adaptation mechanisms. The main reason being that it is highly undesirable to connect all the sensors and actuators in a large structure to a central processor. It is rather desirable to have local decision-making at each smart patch. Furthermore, this local controllers should be easily `expandable' to `contractible.' This corresponds to the fact that addition/deletion of several smart patches should not require a total redesign of the control system. The decentralized control strategies advocated in this paper are of expandable/contractible type. On another front, we are considering utilization of micro-strip antennas for power transfer to and from smart structures. We have made preliminary contributions in this direction and further developments are underway. These approaches are being pursued for active vibration damping and noise cancellation via piezoelectric ceramics although the methodology is general enough to be applicable to other type of active structures.

On the decentralized observer/controller strategy for disturbance rejection

NASA Astrophysics Data System (ADS)

Faria, Cassio T.; Dong, ZhongZhe; Zhang, Xueji

2017-04-01

Centralized controllers and state estimation strategies are the most common topology implemented for disturbance rejection in smart systems. Although this architecture has been proven to be feasible the advances in computation power and size of logic devices can also enable the implementation of decentralized strategies which, on a large scale, can lead to an overall reliability increase of the system. The goal of this paper is to present this concept within the field of disturbance rejection for smart systems and to explore its capabilities and bottlenecks. A simple example is carried out for a composite plate with two controller/estimator centers. Simulation is used to validate the efficacy of the topology and a design procedure is proposed to guarantee the consensus of the agents within the network.

The role of human-automation consensus in multiple unmanned vehicle scheduling.

PubMed

Cummings, M L; Clare, Andrew; Hart, Christin

2010-02-01

This study examined the impact of increasing automation replanning rates on operator performance and workload when supervising a decentralized network of heterogeneous unmanned vehicles. Futuristic unmanned vehicles systems will invert the operator-to-vehicle ratio so that one operator can control multiple dissimilar vehicles connected through a decentralized network. Significant human-automation collaboration will be needed because of automation brittleness, but such collaboration could cause high workload. Three increasing levels of replanning were tested on an existing multiple unmanned vehicle simulation environment that leverages decentralized algorithms for vehicle routing and task allocation in conjunction with human supervision. Rapid replanning can cause high operator workload, ultimately resulting in poorer overall system performance. Poor performance was associated with a lack of operator consensus for when to accept the automation's suggested prompts for new plan consideration as well as negative attitudes toward unmanned aerial vehicles in general. Participants with video game experience tended to collaborate more with the automation, which resulted in better performance. In decentralized unmanned vehicle networks, operators who ignore the automation's requests for new plan consideration and impose rapid replans both increase their own workload and reduce the ability of the vehicle network to operate at its maximum capacity. These findings have implications for personnel selection and training for futuristic systems involving human collaboration with decentralized algorithms embedded in networks of autonomous systems.

Ecology Based Decentralized Agent Management System

NASA Technical Reports Server (NTRS)

Peysakhov, Maxim D.; Cicirello, Vincent A.; Regli, William C.

2004-01-01

The problem of maintaining a desired number of mobile agents on a network is not trivial, especially if we want a completely decentralized solution. Decentralized control makes a system more r e bust and less susceptible to partial failures. The problem is exacerbated on wireless ad hoc networks where host mobility can result in significant changes in the network size and topology. In this paper we propose an ecology-inspired approach to the management of the number of agents. The approach associates agents with living organisms and tasks with food. Agents procreate or die based on the abundance of uncompleted tasks (food). We performed a series of experiments investigating properties of such systems and analyzed their stability under various conditions. We concluded that the ecology based metaphor can be successfully applied to the management of agent populations on wireless ad hoc networks.

Decentralized Formation Flying Control in a Multiple-Team Hierarchy

NASA Technical Reports Server (NTRS)

Mueller, Joseph .; Thomas, Stephanie J.

2005-01-01

This paper presents the prototype of a system that addresses these objectives-a decentralized guidance and control system that is distributed across spacecraft using a multiple-team framework. The objective is to divide large clusters into teams of manageable size, so that the communication and computational demands driven by N decentralized units are related to the number of satellites in a team rather than the entire cluster. The system is designed to provide a high-level of autonomy, to support clusters with large numbers of satellites, to enable the number of spacecraft in the cluster to change post-launch, and to provide for on-orbit software modification. The distributed guidance and control system will be implemented in an object-oriented style using MANTA (Messaging Architecture for Networking and Threaded Applications). In this architecture, tasks may be remotely added, removed or replaced post-launch to increase mission flexibility and robustness. This built-in adaptability will allow software modifications to be made on-orbit in a robust manner. The prototype system, which is implemented in MATLAB, emulates the object-oriented and message-passing features of the MANTA software. In this paper, the multiple-team organization of the cluster is described, and the modular software architecture is presented. The relative dynamics in eccentric reference orbits is reviewed, and families of periodic, relative trajectories are identified, expressed as sets of static geometric parameters. The guidance law design is presented, and an example reconfiguration scenario is used to illustrate the distributed process of assigning geometric goals to the cluster. Next, a decentralized maneuver planning approach is presented that utilizes linear-programming methods to enact reconfiguration and coarse formation keeping maneuvers. Finally, a method for performing online collision avoidance is discussed, and an example is provided to gauge its performance.

Back to basics: does decentralization improve health system performance? Evidence from Ceara in north-east Brazil.

PubMed Central

Atkinson, Sarah; Haran, Dave

2004-01-01

OBJECTIVE: To examine whether decentralization has improved health system performance in the State of Ceara, north-east Brazil. METHODS: Ceara is strongly committed to decentralization. A survey across 45 local (municipio) health systems collected data on performance and formal organization, including decentralization, informal management and local political culture. The indicators for informal management and local political culture were based on prior ethnographic research. Data were analysed using analysis of variance, Duncan's post-hoc test and multiple regression. FINDINGS: Decentralization was associated with improved performance, but only for 5 of our 22 performance indicators. Moreover, in the multiple regression, decentralization explained the variance in only one performance indicator; indicators for informal management and political culture appeared to be more important influences. However, some indicators for informal management were themselves associated with decentralization but not any of the political culture indicators. CONCLUSION: Good management practices in the study led to decentralized local health systems rather than vice versa. Any apparent association between decentralization and performance seems to be an artefact of the informal management, and the wider political culture in which a local health system is embedded strongly influences the performance of local health systems. PMID:15640917

Flexible Multi agent Algorithm for Distributed Decision Making

DTIC Science & Technology

2015-01-01

How, J. P. Consensus - Based Auction Approaches for Decentralized task Assignment. Proceedings of the AIAA Guidance, Navigation, and Control...G. ; Kim, Y. Market- based Decentralized Task Assignment for Cooperative UA V Mission Including Rendezvous. Proceedings of the AIAA Guidance...scalable and adaptable to a variety of specific mission tasks . Additionally, the algorithm could easily be adapted for use on land or sea- based systems

Formation Flying for Satellites and UAVs

NASA Technical Reports Server (NTRS)

Merrill, Garrick; Becker, Chris

2015-01-01

A formation monitoring and control system was developed utilizing mesh networking and decentralized control. Highlights of this system include low latency, seamless addition and removal of vehicles, network relay functionality, and the ability to run on a variety of hardware.

Organically Grown Architectures: Creating Decentralized, Autonomous Systems by Embryomorphic Engineering

NASA Astrophysics Data System (ADS)

Doursat, René

Exploding growth growth in computational systems forces us to gradually replace rigid design and control with decentralization and autonomy. Information technologies will progress, instead, by"meta-designing" mechanisms of system self-assembly, self-regulation and evolution. Nature offers a great variety of efficient complex systems, in which numerous small elements form large-scale, adaptive patterns. The new engineering challenge is to recreate this self-organization and let it freely generate innovative designs under guidance. This article presents an original model of artificial system growth inspired by embryogenesis. A virtual organism is a lattice of cells that proliferate, migrate and self-pattern into differentiated domains. Each cell's fate is controlled by an internal gene regulatory network network. Embryomorphic engineering emphasizes hyperdistributed architectures, and their development as a prerequisite of evolutionary design.

Minimization of transmission cost in decentralized control systems

NASA Technical Reports Server (NTRS)

Wang, S.-H.; Davison, E. J.

1978-01-01

This paper considers the problem of stabilizing a linear time-invariant multivariable system by using local feedback controllers and some limited information exchange among local stations. The problem of achieving a given degree of stability with minimum transmission cost is solved.

A distributed finite-element modeling and control approach for large flexible structures

NASA Technical Reports Server (NTRS)

Young, K. D.

1989-01-01

An unconventional framework is described for the design of decentralized controllers for large flexible structures. In contrast to conventional control system design practice which begins with a model of the open loop plant, the controlled plant is assembled from controlled components in which the modeling phase and the control design phase are integrated at the component level. The developed framework is called controlled component synthesis (CCS) to reflect that it is motivated by the well developed Component Mode Synthesis (CMS) methods which were demonstrated to be effective for solving large complex structural analysis problems for almost three decades. The design philosophy behind CCS is also closely related to that of the subsystem decomposition approach in decentralized control.

Decentralized finite-time attitude synchronization for multiple rigid spacecraft via a novel disturbance observer.

PubMed

Zong, Qun; Shao, Shikai

2016-11-01

This paper investigates decentralized finite-time attitude synchronization for a group of rigid spacecraft by using quaternion with the consideration of environmental disturbances, inertia uncertainties and actuator saturation. Nonsingular terminal sliding mode (TSM) is used for controller design. Firstly, a theorem is proven that there always exists a kind of TSM that converges faster than fast terminal sliding mode (FTSM) for quaternion-descripted attitude control system. Controller with this kind of TSM has faster convergence and reduced computation than FTSM controller. Then, combining with an adaptive parameter estimation strategy, a novel terminal sliding mode disturbance observer is proposed. The proposed disturbance observer needs no upper bound information of the lumped uncertainties or their derivatives. On the basis of undirected topology and the disturbance observer, decentralized attitude synchronization control laws are designed and all attitude errors are ensured to converge to small regions in finite time. As for actuator saturation problem, an auxiliary variable is introduced and accommodated by the disturbance observer. Finally, simulation results are given and the effectiveness of the proposed control scheme is testified. Copyright © 2016. Published by Elsevier Ltd.

Intelligent Reconfigurable System with Self-Dammage Assessmentand Control Stress Capabilities

NASA Astrophysics Data System (ADS)

Trivailo, P.; Plotnikova, L.; Kao, T. W.

2002-01-01

Modern space structures are constructed using a modular approach that facilitates their transportation and assembly in space. Modular architecture of space structures also enables reconfiguration of large structures such that they can adapt to possible changes in environment, and also allows use of the limited structural resources available in space for completion of a much larger variety of tasks. An increase in size and complexity demands development of materials with a "smart" or active structural modulus and also of effective control algorithms to control the motion of large flexible structures. This challenging task has generated a lot of interest amongst scientists and engineers during the last two decades, however, research into the development of control schemes which can adapt to structural configuration changes has received less attention. This is possibly due to the increased complexity caused by alterations in geometry, which inevitably lead to changes in the dynamic properties of the system. This paper presents results of the application of a decentralized control approach for active control of large flexible structures undergoing significant reconfigurations. The Control Component Synthesis methodology was used to build controlled components and to assemble them into a controlled flexible structure that meets required performance specifications. To illustrate the efficiency of the method, numerical simulations were conducted for 2D and 3D modular truss structures and a multi-link beam system. In each case the performance of the decentralized control system has been evaluated using pole location maps, step and impulse response simulations and frequency response analysis. The performance of the decentralized control system has been measured against the optimal centralised control system for various excitation scenarios. A special case where one of the local component controllers fails was also examined. For better interpretation of the efficiency of the designed controllers, results of the simulations are illustrated using a Virtual Reality computer environment, offering advanced visual effects. Plotnikova@rmit.edu.au # Tsunwah@hotmail.com

Algorithms for output feedback, multiple-model, and decentralized control problems

NASA Technical Reports Server (NTRS)

Halyo, N.; Broussard, J. R.

1984-01-01

The optimal stochastic output feedback, multiple-model, and decentralized control problems with dynamic compensation are formulated and discussed. Algorithms for each problem are presented, and their relationship to a basic output feedback algorithm is discussed. An aircraft control design problem is posed as a combined decentralized, multiple-model, output feedback problem. A control design is obtained using the combined algorithm. An analysis of the design is presented.

Real-Time Decentralized Neural Control via Backstepping for a Robotic Arm Powered by Industrial Servomotors.

PubMed

Vazquez, Luis A; Jurado, Francisco; Castaneda, Carlos E; Santibanez, Victor

2018-02-01

This paper presents a continuous-time decentralized neural control scheme for trajectory tracking of a two degrees of freedom direct drive vertical robotic arm. A decentralized recurrent high-order neural network (RHONN) structure is proposed to identify online, in a series-parallel configuration and using the filtered error learning law, the dynamics of the plant. Based on the RHONN subsystems, a local neural controller is derived via backstepping approach. The effectiveness of the decentralized neural controller is validated on a robotic arm platform, of our own design and unknown parameters, which uses industrial servomotors to drive the joints.

Design and implementation of robust decentralized control laws for the ACES structure at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Collins, Emmanuel G., Jr.; Phillips, Douglas; Hyland, David C.

1990-01-01

An experiment was conducted to design controllers that would provide substantial reduction of line-of-sight control errors. The satisfaction of this objective required the controllers to attenuate the beam vibration significantly. Particular emphasis was placed on controller simplicity (i.e., reduced-order and decentralized controller architectures). Complexity reduction in control law implementation is of paramount interest due to stringent limitations on throughput of even state-of-the-art space qualified processors. The results of this experiment successfully demonstrate active vibrator control for a flexible structure. The testbed is the ACES structure at the NASA Marshall Space Flight Center. The ACES structure is dynamically traceable to future space systems and especially allows the study of line-of-sight control issues.

Quantitative Reevaluation of the Effects of Short- and Long-Term Removal of Descending Modulatory Inputs on the Pyloric Rhythm of the Crab, Cancer borealis1,2,3

PubMed Central

Hamood, Albert W.; Haddad, Sara A.; Otopalik, Adriane G.; Rosenbaum, Philipp

2015-01-01

Abstract The crustacean stomatogastric ganglion (STG) receives descending neuromodulatory inputs from three anterior ganglia: the paired commissural ganglia (CoGs), and the single esophageal ganglion (OG). In this paper, we provide the first detailed and quantitative analyses of the short- and long-term effects of removal of these descending inputs (decentralization) on the pyloric rhythm of the STG. Thirty minutes after decentralization, the mean frequency of the pyloric rhythm dropped from 1.20 Hz in control to 0.52 Hz. Whereas the relative phase of pyloric neuron activity was approximately constant across frequency in the controls, after decentralization this changed markedly. Nine control preparations kept for 5–6 d in vitro maintained pyloric rhythm frequencies close to their initial values. Nineteen decentralized preparations kept for 5–6 d dropped slightly in frequency from those seen at 30 min following decentralization, but then displayed stable activity over 6 d. Bouts of higher frequency activity were intermittently seen in both control and decentralized preparations, but the bouts began earlier and were more frequent in the decentralized preparations. Although the bouts may indicate that the removal of the modulatory inputs triggered changes in neuronal excitability, these changes did not produce obvious long-lasting changes in the frequency of the decentralized preparations. PMID:25914899

Decentralized digital adaptive control of robot motion

NASA Technical Reports Server (NTRS)

Tarokh, M.

1990-01-01

A decentralized model reference adaptive scheme is developed for digital control of robot manipulators. The adaptation laws are derived using hyperstability theory, which guarantees asymptotic trajectory tracking despite gross robot parameter variations. The control scheme has a decentralized structure in the sense that each local controller receives only its joint angle measurement to produce its joint torque. The independent joint controllers have simple structures and can be programmed using a very simple and computationally fast algorithm. As a result, the scheme is suitable for real-time motion control.

Mitigation of Remedial Action Schemes by Decentralized Robust Governor Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizondo, Marcelo A.; Marinovici, Laurentiu D.; Lian, Jianming

This paper presents transient stability improvement by a new distributed hierarchical control architecture (DHC). The integration of remedial action schemes (RAS) to the distributed hierarchical control architecture is studied. RAS in power systems are designed to maintain stability and avoid undesired system conditions by rapidly switching equipment and/or changing operating points according to predetermined rules. The acceleration trend relay currently in use in the US western interconnection is an example of RAS that trips generators to maintain transient stability. The link between RAS and DHC is through fast acting robust turbine/governor control that can also improve transient stability. In thismore » paper, the influence of the decentralized robust turbine/governor control on the design of RAS is studied. Benefits of combining these two schemes are increasing power transfer capability and mitigation of RAS generator tripping actions; the later benefit is shown through simulations.« less

SPHERES tethered formation flight testbed: application to NASA's SPECS mission

NASA Astrophysics Data System (ADS)

Chung, Soon-Jo; Kong, Edmund M.; Miller, David W.

2005-08-01

This paper elaborates on theory and experiment of the formation flight control for the future space-borne tethered interferometers. The nonlinear equations of multi-vehicle tethered spacecraft system are derived by Lagrange equations and decoupling method. The preliminary analysis predicts unstable dynamics depending on the direction of the tether motor. The controllability analysis indicates that both array resizing and spin-up are fully controllable only by the reaction wheels and the tether motor, thereby eliminating the need for thrusters. Linear and nonlinear decentralized control techniques have been implemented into the tethered SPHERES testbed, and tested at the NASA MSFC's flat floor facility using two and three SPHERES configurations. The nonlinear control using feedback linearization technique performed successfully in both two SPHERES in-line configuration and three triangular configuration while varying the tether length. The relative metrology system, using the ultra sound metrology system and the inertial sensors as well as the decentralized nonlinear estimator, is developed to provide necessary state information.

Decentralized Interleaving of Paralleled Dc-Dc Buck Converters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Brian B; Rodriguez, Miguel; Sinha, Mohit

We present a decentralized control strategy that yields switch interleaving among parallel-connected dc-dc buck converters. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform and no communication between different controllers is needed. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work presents themore » first fully decentralized strategy for switch interleaving in paralleled dc-dc buck converters.« less

Combat Systems Vision 2030 Conceptual Design of Control Structures for Combat Systems

DTIC Science & Technology

1992-02-01

IEEE, 68(6), pp. 644-654, 1980. 26. Singh , M. G.; Titli, A.; and Malinowski, K.; "Decentralized Control Design: An Overview," Large Scale Systems...IFAC Symposium, pp. 335-339, 1988. 40. Cameron, E. J.; Petschenik, N. H.; Ruston, Lillian; Shah, Swati ; and Srinidhi, Hassan, (Bell Communications

Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Brian B; Rodriguez, Miguel; Sinha, Mohit

We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy formore » switch interleaving of paralleled dc-dc buck converters.« less

Centralized versus decentralized decision-making for recycled material flows.

PubMed

Hong, I-Hsuan; Ammons, Jane C; Realff, Matthew J

2008-02-15

A reverse logistics system is a network of transportation logistics and processing functions that collect, consolidate, refurbish, and demanufacture end-of-life products. This paper examines centralized and decentralized models of decision-making for material flows and associated transaction prices in reverse logistics networks. We compare the application of a centralized model for planning reverse production systems, where a single planner is acquainted with all of the system information and has the authority to determine decision variables for the entire system, to a decentralized approach. In the decentralized approach, the entities coordinate between tiers of the system using a parametrized flow function and compete within tiers based on reaching a price equilibrium. We numerically demonstrate the increase in the total net profit of the centralized system relative to the decentralized one. This implies that one may overestimate the system material flows and profit if the system planner utilizes a centralized viewto predict behaviors of independent entities in the system and that decentralized contract mechanisms will require careful design to avoid losses in the efficiency and scope of these systems.

Administrative Decentralization in School Systems and Its Effect on the Organization of Media Services. Atlanta Public Schools: A Case Study.

ERIC Educational Resources Information Center

Williams, R. David

This study reviews the literature on public school administration and on decentralization to establish the groundwork for an analysis of the administration of a decentralized school system and its media services, discusses some of the confusion in the centralization vs. decentralization debate, and presents a heuristic study of the administration…

Decentralized event-triggered consensus control strategy for leader-follower networked systems

NASA Astrophysics Data System (ADS)

Zhang, Shouxu; Xie, Duosi; Yan, Weisheng

2017-08-01

In this paper, the consensus problem of leader-follower networked systems is addressed. At first, a centralized and a decentralized event-triggered control strategy are proposed, which make the control actuators of followers update at aperiodic invent interval. In particular, the latter one makes each follower requires the local information only. After that, an improved triggering function that only uses the follower's own information and the neighbors' states at their latest event instants is developed to relax the requirement of the continuous state of the neighbors. In addition, the strategy does not require the information of the topology, nor the eigenvalues of the Laplacian matrix. And if the follower does not have direct connection to the leader, the leader's information is not required either. It is analytically shown that by using the proposed strategy the leader-follower networked system is able to reach consensus without continuous communication among followers. Simulation examples are given to show effectiveness of the proposed control strategy.

Decentralized event-triggered synchronization of uncertain Markovian jumping neutral-type neural networks with mixed delays.

PubMed

Senan, Sibel; Syed Ali, M; Vadivel, R; Arik, Sabri

2017-02-01

In this study, we present an approach for the decentralized event-triggered synchronization of Markovian jumping neutral-type neural networks with mixed delays. We present a method for designing decentralized event-triggered synchronization, which only utilizes locally available information, in order to determine the time instants for transmission from sensors to a central controller. By applying a novel Lyapunov-Krasovskii functional, as well as using the reciprocal convex combination method and some inequality techniques such as Jensen's inequality, we obtain several sufficient conditions in terms of a set of linear matrix inequalities (LMIs) under which the delayed neural networks are stochastically stable in terms of the error systems. Finally, we conclude that the drive systems synchronize stochastically with the response systems. We show that the proposed stability criteria can be verified easily using the numerically efficient Matlab LMI toolbox. The effectiveness and feasibility of the results obtained are verified by numerical examples. Copyright © 2016 Elsevier Ltd. All rights reserved.

On l(1): Optimal decentralized performance

NASA Technical Reports Server (NTRS)

Sourlas, Dennis; Manousiouthakis, Vasilios

1993-01-01

In this paper, the Manousiouthakis parametrization of all decentralized stabilizing controllers is employed in mathematically formulating the l(sup 1) optimal decentralized controller synthesis problem. The resulting optimization problem is infinite dimensional and therefore not directly amenable to computations. It is shown that finite dimensional optimization problems that have value arbitrarily close to the infinite dimensional one can be constructed. Based on this result, an algorithm that solves the l(sup 1) decentralized performance problems is presented. A global optimization approach to the solution of the infinite dimensional approximating problems is also discussed.

Decentralized Control of Autonomous Vehicles

DTIC Science & Technology

2003-01-01

Autonomous Vehicles by John S. Baras, Xiaobo Tan, Pedram Hovareshti CSHCN TR 2003-8 (ISR TR 2003-14) Report Documentation Page Form ApprovedOMB No. 0704...AND SUBTITLE Decentralized Control of Autonomous Vehicles 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Decentralized Control of Autonomous Vehicles ∗ John S. Baras, Xiaobo Tan, and Pedram

Research on Coordination of Fresh Produce Supply Chain in Big Market Sales Environment

PubMed Central

Su, Juning; Liu, Chenguang

2014-01-01

In this paper, we propose two decision models for decentralized and centralized fresh produce supply chains with stochastic supply and demand and controllable transportation time. The optimal order quantity and the optimal transportation time in these two supply chain systems are derived. To improve profits in a decentralized supply chain, based on analyzing the risk taken by each participant in the supply chain, we design a set of contracts which can coordinate this type of fresh produce supply chain with stochastic supply and stochastic demand, and controllable transportation time as well. We also obtain a value range of contract parameters that can increase profits of all participants in the decentralized supply chain. The expected profits of the decentralized setting and the centralized setting are compared with respect to given numerical examples. Furthermore, the sensitivity analyses of the deterioration rate factor and the freshness factor are performed. The results of numerical examples show that the transportation time is shorter, the order quantity is smaller, the total profit of whole supply chain is less, and the possibility of cooperation between supplier and retailer is higher for the fresh produce which is more perishable and its quality decays more quickly. PMID:24764770

Research on coordination of fresh produce supply chain in big market sales environment.

PubMed

Su, Juning; Wu, Jiebing; Liu, Chenguang

2014-01-01

In this paper, we propose two decision models for decentralized and centralized fresh produce supply chains with stochastic supply and demand and controllable transportation time. The optimal order quantity and the optimal transportation time in these two supply chain systems are derived. To improve profits in a decentralized supply chain, based on analyzing the risk taken by each participant in the supply chain, we design a set of contracts which can coordinate this type of fresh produce supply chain with stochastic supply and stochastic demand, and controllable transportation time as well. We also obtain a value range of contract parameters that can increase profits of all participants in the decentralized supply chain. The expected profits of the decentralized setting and the centralized setting are compared with respect to given numerical examples. Furthermore, the sensitivity analyses of the deterioration rate factor and the freshness factor are performed. The results of numerical examples show that the transportation time is shorter, the order quantity is smaller, the total profit of whole supply chain is less, and the possibility of cooperation between supplier and retailer is higher for the fresh produce which is more perishable and its quality decays more quickly.

Research directions in large scale systems and decentralized control

NASA Technical Reports Server (NTRS)

Tenney, R. R.

1980-01-01

Control theory provides a well established framework for dealing with automatic decision problems and a set of techniques for automatic decision making which exploit special structure, but it does not deal well with complexity. The potential exists for combining control theoretic and knowledge based concepts into a unified approach. The elements of control theory are diagrammed, including modern control and large scale systems.

Some aspects of control of a large-scale dynamic system

NASA Technical Reports Server (NTRS)

Aoki, M.

1975-01-01

Techniques of predicting and/or controlling the dynamic behavior of large scale systems are discussed in terms of decentralized decision making. Topics discussed include: (1) control of large scale systems by dynamic team with delayed information sharing; (2) dynamic resource allocation problems by a team (hierarchical structure with a coordinator); and (3) some problems related to the construction of a model of reduced dimension.

NASA Mars rover: a testbed for evaluating applications of covariance intersection

NASA Astrophysics Data System (ADS)

Uhlmann, Jeffrey K.; Julier, Simon J.; Kamgar-Parsi, Behzad; Lanzagorta, Marco O.; Shyu, Haw-Jye S.

1999-07-01

The Naval Research Laboratory (NRL) has spearheaded the development and application of Covariance Intersection (CI) for a variety of decentralized data fusion problems. Such problems include distributed control, onboard sensor fusion, and dynamic map building and localization. In this paper we describe NRL's development of a CI-based navigation system for the NASA Mars rover that stresses almost all aspects of decentralized data fusion. We also describe how this project relates to NRL's augmented reality, advanced visualization, and REBOT projects.

Interdependent Network Recovery Games.

PubMed

Smith, Andrew M; González, Andrés D; Dueñas-Osorio, Leonardo; D'Souza, Raissa M

2017-10-30

Recovery of interdependent infrastructure networks in the presence of catastrophic failure is crucial to the economy and welfare of society. Recently, centralized methods have been developed to address optimal resource allocation in postdisaster recovery scenarios of interdependent infrastructure systems that minimize total cost. In real-world systems, however, multiple independent, possibly noncooperative, utility network controllers are responsible for making recovery decisions, resulting in suboptimal decentralized processes. With the goal of minimizing recovery cost, a best-case decentralized model allows controllers to develop a full recovery plan and negotiate until all parties are satisfied (an equilibrium is reached). Such a model is computationally intensive for planning and negotiating, and time is a crucial resource in postdisaster recovery scenarios. Furthermore, in this work, we prove this best-case decentralized negotiation process could continue indefinitely under certain conditions. Accounting for network controllers' urgency in repairing their system, we propose an ad hoc sequential game-theoretic model of interdependent infrastructure network recovery represented as a discrete time noncooperative game between network controllers that is guaranteed to converge to an equilibrium. We further reduce the computation time needed to find a solution by applying a best-response heuristic and prove bounds on ε-Nash equilibrium, where ε depends on problem inputs. We compare best-case and ad hoc models on an empirical interdependent infrastructure network in the presence of simulated earthquakes to demonstrate the extent of the tradeoff between optimality and computational efficiency. Our method provides a foundation for modeling sociotechnical systems in a way that mirrors restoration processes in practice. © 2017 Society for Risk Analysis.

Performance of centralized versus decentralized tuberculosis treatment services in Southern Brazil, 2006-2015.

PubMed

Scheffer, Mara Cristina; Prim, Rodrigo Ivan; Wildner, Leticia Muraro; Medeiros, Taiane Freitas; Maurici, Rosemeri; Kupek, Emil; Bazzo, Maria Luiza

2018-04-25

Tuberculosis (TB) control programs face the challenges of decreasing incidence, mortality rates, and drug resistance while increasing treatment adherence. The Brazilian TB control program recommended the decentralization of patient care as a strategy for combating the disease. This study evaluated the performance of this policy in an area with high default rates, comparing epidemiological and operational indicators between two similar municipalities. This study analyzed epidemiological and operational indicators on new cases of pulmonary tuberculosis reported in the Brazilian Notifiable Diseases Information System between 2006 and 2015. In addition, to characterize differences between the populations of the two studied municipalities, a prospective cohort study was conducted between 2014 and 2015, in which patients with new cases of culture-confirmed pulmonary tuberculosis were interviewed and monitored until the disease outcome. A descriptive analysis, the chi-square test, and a Poisson regression model were employed to compare TB treatment outcomes and health care indicators between the municipalities. Two thousand three hundred nine cases were evaluated, of which 207 patients were interviewed. Over the 2006-2015 period, TB incidence per 100,000 population in the municipality with decentralized care was significantly higher (39%, 95% CI 27-49%) in comparison to that of the municipality with centralized care. TB treatment default rate (45%, 95% CI 12-90%) was also higher in the municipality with decentralized care. During the two-year follow-up, significant differences were found between patients in centralized care and those in decentralized care regarding treatment success (84.5 vs. 66.1%), treatment default (10.7 vs. 25.8%), illicit drug use (27.7 vs. 45.9%), and homelessness (3.6 vs. 12.9%). The operational indicators revealed that the proportion of control smear tests, medical imaging, and HIV tests were all significantly higher in the centralized care. However, a significantly higher proportion of patients started treatment in the early stages of the disease in the municipality with decentralized care. These data showed a low success rate in TB treatment in both municipalities. Decentralization of TB care, alone, did not improve the main epidemiological and operational indicators related to disease control when compared to centralized care. Full implementation of strategies already recommended is needed to improve TB treatment success rates.

Comparative Perspectives on Educational Decentralization: An Exercise in Contradiction?

ERIC Educational Resources Information Center

Weiler, Hans N.

1990-01-01

It is argued that policies decentralizing the governance of educational systems, although appealing in the abstract, tend to be fundamentally ambivalent and in conflict with powerful forces favoring centralization. Tensions surrounding the issue of decentralization are discussed, with emphasis on the relationship between decentralization and…

Robust Power Management Control for Stand-Alone Hybrid Power Generation System

NASA Astrophysics Data System (ADS)

Kamal, Elkhatib; Adouane, Lounis; Aitouche, Abdel; Mohammed, Walaa

2017-01-01

This paper presents a new robust fuzzy control of energy management strategy for the stand-alone hybrid power systems. It consists of two levels named centralized fuzzy supervisory control which generates the power references for each decentralized robust fuzzy control. Hybrid power systems comprises: a photovoltaic panel and wind turbine as renewable sources, a micro turbine generator and a battery storage system. The proposed control strategy is able to satisfy the load requirements based on a fuzzy supervisor controller and manage power flows between the different energy sources and the storage unit by respecting the state of charge and the variation of wind speed and irradiance. Centralized controller is designed based on If-Then fuzzy rules to manage and optimize the hybrid power system production by generating the reference power for photovoltaic panel and wind turbine. Decentralized controller is based on the Takagi-Sugeno fuzzy model and permits us to stabilize each photovoltaic panel and wind turbine in presence of disturbances and parametric uncertainties and to optimize the tracking reference which is given by the centralized controller level. The sufficient conditions stability are formulated in the format of linear matrix inequalities using the Lyapunov stability theory. The effectiveness of the proposed Strategy is finally demonstrated through a SAHPS (stand-alone hybrid power systems) to illustrate the effectiveness of the overall proposed method.

Consensus-based distributed cooperative learning from closed-loop neural control systems.

PubMed

Chen, Weisheng; Hua, Shaoyong; Zhang, Huaguang

2015-02-01

In this paper, the neural tracking problem is addressed for a group of uncertain nonlinear systems where the system structures are identical but the reference signals are different. This paper focuses on studying the learning capability of neural networks (NNs) during the control process. First, we propose a novel control scheme called distributed cooperative learning (DCL) control scheme, by establishing the communication topology among adaptive laws of NN weights to share their learned knowledge online. It is further proved that if the communication topology is undirected and connected, all estimated weights of NNs can converge to small neighborhoods around their optimal values over a domain consisting of the union of all state orbits. Second, as a corollary it is shown that the conclusion on the deterministic learning still holds in the decentralized adaptive neural control scheme where, however, the estimated weights of NNs just converge to small neighborhoods of the optimal values along their own state orbits. Thus, the learned controllers obtained by DCL scheme have the better generalization capability than ones obtained by decentralized learning method. A simulation example is provided to verify the effectiveness and advantages of the control schemes proposed in this paper.

A Hierarchical Framework for Demand-Side Frequency Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moya, Christian; Zhang, Wei; Lian, Jianming

2014-06-02

With large-scale plans to integrate renewable generation, more resources will be needed to compensate for the uncertainty associated with intermittent generation resources. Under such conditions, performing frequency control using only supply-side resources become not only prohibitively expensive but also technically difficult. It is therefore important to explore how a sufficient proportion of the loads could assume a routine role in frequency control to maintain the stability of the system at an acceptable cost. In this paper, a novel hierarchical decentralized framework for frequency based load control is proposed. The framework involves two decision layers. The top decision layer determines themore » optimal droop gain required from the aggregated load response on each bus using a robust decentralized control approach. The second layer consists of a large number of devices, which switch probabilistically during contingencies so that the aggregated power change matches the desired droop amount according to the updated gains. The proposed framework is based on the classical nonlinear multi-machine power system model, and can deal with timevarying system operating conditions while respecting the physical constraints of individual devices. Realistic simulation results based on a 68-bus system are provided to demonstrate the effectiveness of the proposed strategy.« less

Convergent method of and apparatus for distributed control of robotic systems using fuzzy logic

DOEpatents

Feddema, John T.; Driessen, Brian J.; Kwok, Kwan S.

2002-01-01

A decentralized fuzzy logic control system for one vehicle or for multiple robotic vehicles provides a way to control each vehicle to converge on a goal without collisions between vehicles or collisions with other obstacles, in the presence of noisy input measurements and a limited amount of compute-power and memory on board each robotic vehicle. The fuzzy controller demonstrates improved robustness to noise relative to an exact controller.

Development of a decentralized multi-axis synchronous control approach for real-time networks.

PubMed

Xu, Xiong; Gu, Guo-Ying; Xiong, Zhenhua; Sheng, Xinjun; Zhu, Xiangyang

2017-05-01

The message scheduling and the network-induced delays of real-time networks, together with the different inertias and disturbances in different axes, make the synchronous control of the real-time network-based systems quite challenging. To address this challenge, a decentralized multi-axis synchronous control approach is developed in this paper. Due to the limitations of message scheduling and network bandwidth, error of the position synchronization is firstly defined in the proposed control approach as a subset of preceding-axis pairs. Then, a motion message estimator is designed to reduce the effect of network delays. It is proven that position and synchronization errors asymptotically converge to zero in the proposed controller with the delay compensation. Finally, simulation and experimental results show that the developed control approach can achieve the good position synchronization performance for the multi-axis motion over the real-time network. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Instructional Television: Do We Have the Courage to Succeed?

ERIC Educational Resources Information Center

Bosner, Paul

1976-01-01

A discussion of instructional television's implementation in terms of massiveness of the system; the decentralization of the system; and the fragmented, overlapping funding structure of the system, which results in obscured centers of power resting somewhere between state and local control, with subtle direction by the federal government.…

Empowerment Schools. Luncheon Series

ERIC Educational Resources Information Center

Kane, Kristen

2006-01-01

For the past half a century, the New York City public school system has undergone major transformations in its organization. The 1950s and 1960s community control movement led to decentralization of the school system in 1969. The school system broke into 32 community school districts, with superintendents appointed by local community school…

After Decentralization: Delimitations and Possibilities within New Fields

ERIC Educational Resources Information Center

Wahlstrom, Ninni

2008-01-01

The shift from a centralized to a decentralized school system can be seen as a solution to an uncertain problem. Through analysing the displacements in the concept of equivalence within Sweden's decentralized school system, this study illustrates how the meaning of the concept of equivalence shifts over time, from a more collective target…

Tilt and decentration of intraocular lenses in vivo from Purkinje and Scheimpflug imaging. Validation study.

PubMed

de Castro, Alberto; Rosales, Patricia; Marcos, Susana

2007-03-01

To measure tilt and decentration of intraocular lenses (IOLs) with Scheimpflug and Purkinje imaging systems in physical model eyes with known amounts of tilt and decentration and patients. Instituto de Optica Daza de Valdés, Consejo Superior de Investigaciones Científicas, Madrid, Spain. Measurements of IOL tilt and decentration were obtained using a commercial Scheimpflug system (Pentacam, Oculus), custom algorithms, and a custom-built Purkinje imaging apparatus. Twenty-five Scheimpflug images of the anterior segment of the eye were obtained at different meridians. Custom algorithms were used to process the images (correction of geometrical distortion, edge detection, and curve fittings). Intraocular lens tilt and decentration were estimated by fitting sinusoidal functions to the projections of the pupillary axis and IOL axis in each image. The Purkinje imaging system captures pupil images showing reflections of light from the anterior corneal surface and anterior and posterior lens surfaces. Custom algorithms were used to detect the Purkinje image locations and estimate IOL tilt and decentration based on a linear system equation and computer eye models with individual biometry. Both methods were validated with a physical model eye in which IOL tilt and decentration can be set nominally. Twenty-one eyes of 12 patients with IOLs were measured with both systems. Measurements of the physical model eye showed an absolute discrepancy between nominal and measured values of 0.279 degree (Purkinje) and 0.243 degree (Scheimpflug) for tilt and 0.094 mm (Purkinje) and 0.228 mm (Scheimpflug) for decentration. In patients, the mean tilt was less than 2.6 degrees and the mean decentration less than 0.4 mm. Both techniques showed mirror symmetry between right eyes and left eyes for tilt around the vertical axis and for decentration in the horizontal axis. Both systems showed high reproducibility. Validation experiments on physical model eyes showed slightly higher accuracy with the Purkinje method than the Scheimpflug imaging method. Horizontal measurements of patients with both techniques were highly correlated. The IOLs tended to be tilted and decentered nasally in most patients.

The Use of Decentralized Control in the Design of a Large Segmented Space Reflector

NASA Technical Reports Server (NTRS)

Ryaciotaki-Boussalis, Helen; Mirmirani, Maj; Rad, Khosrow; Morales, Mauricio; Velazquez, Efrain; Chassiakos, Anastasios; Luzardo, Jose-Alberto

1997-01-01

The 3-dimensional model for a segmented reflector telescope is developed using finite element techniques. The structure is decomposed into six subsystems. System control design using neural networks is performed. Performance evaluation is demonstrated via simulation using PRO-MATLAB and SIMULINK.

Decentralized state estimation for a large-scale spatially interconnected system.

PubMed

Liu, Huabo; Yu, Haisheng

2018-03-01

A decentralized state estimator is derived for the spatially interconnected systems composed of many subsystems with arbitrary connection relations. An optimization problem on the basis of linear matrix inequality (LMI) is constructed for the computations of improved subsystem parameter matrices. Several computationally effective approaches are derived which efficiently utilize the block-diagonal characteristic of system parameter matrices and the sparseness of subsystem connection matrix. Moreover, this decentralized state estimator is proved to converge to a stable system and obtain a bounded covariance matrix of estimation errors under certain conditions. Numerical simulations show that the obtained decentralized state estimator is attractive in the synthesis of a large-scale networked system. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

32 CFR Appendix F to Part 505 - Example of a System of Records Notice

Code of Federal Regulations, 2012 CFR

2012-07-01

...) System Location: Specify the address of the primary system and any decentralized elements, including... title and duty address of the system manager. For decentralized systems, show the locations, the...

32 CFR Appendix F to Part 505 - Example of a System of Records Notice

Code of Federal Regulations, 2014 CFR

2014-07-01

...) System Location: Specify the address of the primary system and any decentralized elements, including... title and duty address of the system manager. For decentralized systems, show the locations, the...

On the stabilization of decentralized control systems.

NASA Technical Reports Server (NTRS)

Wang, S.-H.; Davison, E. J.

1973-01-01

This paper considers the problem of stabilizing a linear time-variant multivariable system by using several local feedback control laws. Each local feedback control law depends only on partial system outputs. A necessary and sufficient condition for the existence of local control laws with dynamic compensation to stabilize a given system is derived. This condition is stated in terms of a new notion, called fixed modes, which is a natural generalization of the well-known concept of uncontrollable modes and unobservable modes that occur in centralized control system problems. A procedure that constructs a set of stabilizing feedback control laws is given.

Decentralized control experiments on the JPL flexible spacecraft

NASA Technical Reports Server (NTRS)

Ozguner, U.; Ossman, K.; Donne, J.; Boesch, M.; Ahmed, A.

1990-01-01

Decentralized control experiments were successfully demonstrated for the JPL/AFAL Flexible Structure. A simulation package using MATRIXx showed strong correlation between the simulations and experimental result, while providing a means for test and debug of the various control strategies. Implementation was simplified by a modular software design that was easily transported from the simulation environment to the experimental environment. Control designs worked well for suppression of the dominant modes of the structure. Static decentralized output feedback dampened the excited modes of the structure, but sometimes excited higher order modes upon startup of the controller. A second-order frequency shaping controller helped to eliminate excitation of the higher order modes by attenuating high frequencies in the control effort. However, it also resulted in slightly longer settling times.

Autonomous Decentralized Control of Supply and Demand by Inverter Based Distributed Generations in Isolated Microgrid

NASA Astrophysics Data System (ADS)

Shiki, Akira; Yokoyama, Akihiko; Baba, Jyunpei; Takano, Tomihiro; Gouda, Takahiro; Izui, Yoshio

Recently, because of the environmental burden mitigation, energy conservations, energy security, and cost reductions, distributed generations are attracting our strong attention. These distributed generations (DGs) have been already installed to the distribution system, and much more DGs will be expected to be connected in the future. On the other hand, a new concept called “Microgrid” which is a small power supply network consisting of only DGs was proposed and some prototype projects are ongoing in Japan. The purpose of this paper is to develop the three-phase instantaneous valued digital simulator of microgrid consisting of a lot of inverter based DGs and to develop a supply and demand control method in isolated microgrid. First, microgrid is modeled using MATLAB/SIMULINK. We develop models of three-phase instantaneous valued inverter type CVCF generator, PQ specified generator, PV specified generator, PQ specified load as storage battery, photovoltaic generation, fuel cell and inverter load respectively. Then we propose an autonomous decentralized control method of supply and demand in isolated microgrid where storage batteries, fuel cells, photovoltaic generations and loads are connected. It is proposed here that the system frequency is used as a means to control DG output. By changing the frequency of the storage battery due to unbalance of supply and demand, all inverter based DGs detect the frequency fluctuation and change their own outputs. Finally, a new frequency control method in autonomous decentralized control of supply and demand is proposed. Though the frequency is used to transmit the information on the supply and demand unbalance to DGs, after the frequency plays the role, the frequency finally has to return to a standard value. To return the frequency to the standard value, the characteristic curve of the fuel cell is shifted in parallel. This control is carried out corresponding to the fluctuation of the load. The simulation shows that the frequency can be controlled well and has been made clear the effectiveness of the frequency control system.

A review on full-scale decentralized wastewater treatment systems: techno-economical approach.

PubMed

Singh, Nitin Kumar; Kazmi, A A; Starkl, M

2015-01-01

As a solution to the shortcomings of centralized systems, over the last two decades large numbers of decentralized wastewater treatment plants of different technology types have been installed all over the world. This paper aims at deriving lessons learned from existing decentralized wastewater treatment plants that are relevant for smaller towns (and peri-urban areas) as well as rural communities in developing countries, such as India. Only full-scale implemented decentralized wastewater treatment systems are reviewed in terms of performance, land area requirement, capital cost, and operation and maintenance costs. The results are presented in tables comparing different technology types with respect to those parameters.

The social control of energy: A case for the promise of decentralized solar technologies

NASA Astrophysics Data System (ADS)

Gilmer, R. W.

1980-05-01

Decentralized solar technology and centralized electric utilities were contrasted in the ways they assign property rights in capital and energy output; in the assignment of operational control; and in the means of monitoring, policing, and enforcing property rights. An analogy was drawn between the decision of an energy consumer to use decentralized solar and the decision of a firm to vertically integrate, that is, to extend the boundary of a the firm to vertically integrate, that is, to extend the boundary of the firm by making inputs or further processing output. Decentralized solar energy production offers the small energy consumer the chance to cut ties to outside suppliers--to vertically integrate energy production into the home or business. The development of this analogy provides insight into important noneconomic aspects of solar energy, and it points clearly to the lighter burdens of social management offered by decentralized solar technology.

Decentralized Control and Multicriterion Decision Making.

DTIC Science & Technology

1979-12-01

stabilizable and detectable? ’V L 42 Theorem 3.1: Existence of stabilizing solution. We assume that the system is jointly controllable R1 (0...a leader’s control that will make the system stabilizable for the follower and that in order for J to be finite the leader must choose F such1 1 that...a stabilizing solution will be developed. We restrict our attention to a formulation dealing with a linear continuous time system and in which

Supporting Continuous Improvement in California's Education System

ERIC Educational Resources Information Center

Darling-Hammond, Linda; Plank, David N.

2015-01-01

California's new accountability system originated in the radical decentralization of power and authority from Sacramento to local schools and their communities brought about by the Legislature's adoption of the Local Control Funding Formula (LCFF) in 2013. Under California's previous accountability policies and the federal "No Child Left…

School-Based Management and Arts Education: Lessons from Chicago

ERIC Educational Resources Information Center

Fitzpatrick, Kate R.

2012-01-01

School-based management, or local school control, is an organizational school reform effort aimed at decentralizing school decision-making that has become prevalent in districts throughout the United States. Using the groundbreaking Chicago system of local school control as an exemplar, this article outlines the implications of such reform efforts…

Generic, scalable and decentralized fault detection for robot swarms.

PubMed

Tarapore, Danesh; Christensen, Anders Lyhne; Timmis, Jon

2017-01-01

Robot swarms are large-scale multirobot systems with decentralized control which means that each robot acts based only on local perception and on local coordination with neighboring robots. The decentralized approach to control confers number of potential benefits. In particular, inherent scalability and robustness are often highlighted as key distinguishing features of robot swarms compared with systems that rely on traditional approaches to multirobot coordination. It has, however, been shown that swarm robotics systems are not always fault tolerant. To realize the robustness potential of robot swarms, it is thus essential to give systems the capacity to actively detect and accommodate faults. In this paper, we present a generic fault-detection system for robot swarms. We show how robots with limited and imperfect sensing capabilities are able to observe and classify the behavior of one another. In order to achieve this, the underlying classifier is an immune system-inspired algorithm that learns to distinguish between normal behavior and abnormal behavior online. Through a series of experiments, we systematically assess the performance of our approach in a detailed simulation environment. In particular, we analyze our system's capacity to correctly detect robots with faults, false positive rates, performance in a foraging task in which each robot exhibits a composite behavior, and performance under perturbations of the task environment. Results show that our generic fault-detection system is robust, that it is able to detect faults in a timely manner, and that it achieves a low false positive rate. The developed fault-detection system has the potential to enable long-term autonomy for robust multirobot systems, thus increasing the usefulness of robots for a diverse repertoire of upcoming applications in the area of distributed intelligent automation.

Energy storage requirements of dc microgrids with high penetration renewables under droop control

DOE PAGES

Weaver, Wayne W.; Robinett, Rush D.; Parker, Gordon G.; ...

2015-01-09

Energy storage is a important design component in microgrids with high penetration renewable sources to maintain the system because of the highly variable and sometimes stochastic nature of the sources. Storage devices can be distributed close to the sources and/or at the microgrid bus. In addition, storage requirements can be minimized with a centralized control architecture, but this creates a single point of failure. Distributed droop control enables a completely decentralized architecture but, the energy storage optimization becomes more difficult. Our paper presents an approach to droop control that enables the local and bus storage requirements to be determined. Givenmore » a priori knowledge of the design structure of a microgrid and the basic cycles of the renewable sources, we found that the droop settings of the sources are such that they minimize both the bus voltage variations and overall energy storage capacity required in the system. This approach can be used in the design phase of a microgrid with a decentralized control structure to determine appropriate droop settings as well as the sizing of energy storage devices.« less

Decentralization of health care systems and health outcomes: Evidence from a natural experiment.

PubMed

Jiménez-Rubio, Dolores; García-Gómez, Pilar

2017-09-01

While many countries worldwide are shifting responsibilities for their health systems to local levels of government, there is to date insufficient evidence about the potential impact of these policy reforms. We estimate the impact of decentralization of the health services on infant and neonatal mortality using a natural experiment: the devolution of health care decision making powers to Spanish regions. The devolution was implemented gradually and asymmetrically over a twenty-year period (1981-2002). The order in which the regions were decentralized was driven by political factors and hence can be considered exogenous to health outcomes. In addition, we exploit the dynamic effect of decentralization of health services and allow for heterogeneous effects by the two main types of decentralization implemented across regions: full decentralization (political and fiscal powers) versus political decentralization only. Our difference in differences results based on a panel dataset for the 50 Spanish provinces over the period 1980 to 2010 show that the lasting benefit of decentralization accrues only to regions which enjoy almost full fiscal and political powers and which are also among the richest regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distributed resource allocation under communication constraints

NASA Astrophysics Data System (ADS)

Dodin, Pierre; Nimier, Vincent

2001-03-01

This paper deals with a study of the multi-sensor management problem for multi-target tracking. The collaboration between many sensors observing the same target means that they are able to fuse their data during the information process. Then one must take into account this possibility to compute the optimal association sensors-target at each step of time. In order to solve this problem for real large scale system, one must both consider the information aspect and the control aspect of the problem. To unify these problems, one possibility is to use a decentralized filtering algorithm locally driven by an assignment algorithm. The decentralized filtering algorithm we use in our model is the filtering algorithm of Grime, which relaxes the usual full-connected hypothesis. By full-connected, one means that the information in a full-connected system is totally distributed everywhere at the same moment, which is unacceptable for a real large scale system. We modelize the distributed assignment decision with the help of a greedy algorithm. Each sensor performs a global optimization, in order to estimate other information sets. A consequence of the relaxation of the full- connected hypothesis is that the sensors' information set are not the same at each step of time, producing an information dis- symmetry in the system. The assignment algorithm uses a local knowledge of this dis-symmetry. By testing the reactions and the coherence of the local assignment decisions of our system, against maneuvering targets, we show that it is still possible to manage with decentralized assignment control even though the system is not full-connected.

Decentralization and central and regional coordination of health services: the case of Switzerland.

PubMed

Wyss, K; Lorenz, N

2000-01-01

As part of reforms in the health care delivery sector, decentralization is currently promoted in many countries as a means to improve performance and outcomes of national health care systems. Switzerland is an example of a country with a long-standing tradition of decentralized organization for many purposes, including health care delivery. Apart from the few aspects where the responsibility is at the federal level, it is the task of the 26 cantons to organize the provision of health services for the population of around 7 million people. This permits the system to be responsive to local priorities and interest as well as to new developments in medical and public health know-how. However, the increasing and complex difficulties of most health care delivery systems raise questions about the need for mechanisms for coordination at federal level, as well as about the equity and the effectiveness of the decentralized approach. The Swiss case shows that in a strongly decentralized system, health policy and strategy elaboration, as well as coordination mechanisms among the regional components of the system, are very hard to establish. This situation may lead to strong regional inequities in the financing of health care as well as to differences in the distribution of financial, human and material inputs into the health system. The study of the Swiss health system reveals also that, within a decentralized framework, the promotion of cost-effective interventions through a well-balanced approach towards promotional, preventive and curative services, or towards ambulatory and hospital care, is difficult to achieve, as agreements between relatively autonomous regions are difficult to obtain. Therefore, a decentralized system is not necessarily the most equitable and cost-effective way to deliver health care.

Resource allocation and budgetary mechanisms for decentralized health systems: experiences from Balochistan, Pakistan.

PubMed

Green, A; Ali, B; Naeem, A; Ross, D

2000-01-01

This paper identifies key political and technical issues involved in the development of an appropriate resource allocation and budgetary system for the public health sector, using experience gained in the Province of Balochistan, Pakistan. The resource allocation and budgetary system is a critical, yet often neglected, component of any decentralization policy. Current systems are often based on historical incrementalism that is neither efficient nor equitable. This article describes technical work carried out in Balochistan to develop a system of resource allocation and budgeting that is needs-based, in line with policies of decentralization, and implementable within existing technical constraints. However, the development of technical systems, while necessary, is not a sufficient condition for the implementation of a resource allocation and decentralized budgeting system. This is illustrated by analysing the constraints that have been encountered in the development of such a system in Balochistan.

Resource allocation and budgetary mechanisms for decentralized health systems: experiences from Balochistan, Pakistan.

PubMed Central

Green, A.; Ali, B.; Naeem, A.; Ross, D.

2000-01-01

This paper identifies key political and technical issues involved in the development of an appropriate resource allocation and budgetary system for the public health sector, using experience gained in the Province of Balochistan, Pakistan. The resource allocation and budgetary system is a critical, yet often neglected, component of any decentralization policy. Current systems are often based on historical incrementalism that is neither efficient nor equitable. This article describes technical work carried out in Balochistan to develop a system of resource allocation and budgeting that is needs-based, in line with policies of decentralization, and implementable within existing technical constraints. However, the development of technical systems, while necessary, is not a sufficient condition for the implementation of a resource allocation and decentralized budgeting system. This is illustrated by analysing the constraints that have been encountered in the development of such a system in Balochistan. PMID:10994286

76 FR 54190 - Proposed Privacy Act System of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-31

... decentralized, with each mission area and agency managing its respective FOIA programs. At the end of each year...-know basis. Role-based access controls are used, and FX is only accessible via the Internet using USDA...

Generic, scalable and decentralized fault detection for robot swarms

PubMed Central

Christensen, Anders Lyhne; Timmis, Jon

2017-01-01

Robot swarms are large-scale multirobot systems with decentralized control which means that each robot acts based only on local perception and on local coordination with neighboring robots. The decentralized approach to control confers number of potential benefits. In particular, inherent scalability and robustness are often highlighted as key distinguishing features of robot swarms compared with systems that rely on traditional approaches to multirobot coordination. It has, however, been shown that swarm robotics systems are not always fault tolerant. To realize the robustness potential of robot swarms, it is thus essential to give systems the capacity to actively detect and accommodate faults. In this paper, we present a generic fault-detection system for robot swarms. We show how robots with limited and imperfect sensing capabilities are able to observe and classify the behavior of one another. In order to achieve this, the underlying classifier is an immune system-inspired algorithm that learns to distinguish between normal behavior and abnormal behavior online. Through a series of experiments, we systematically assess the performance of our approach in a detailed simulation environment. In particular, we analyze our system’s capacity to correctly detect robots with faults, false positive rates, performance in a foraging task in which each robot exhibits a composite behavior, and performance under perturbations of the task environment. Results show that our generic fault-detection system is robust, that it is able to detect faults in a timely manner, and that it achieves a low false positive rate. The developed fault-detection system has the potential to enable long-term autonomy for robust multirobot systems, thus increasing the usefulness of robots for a diverse repertoire of upcoming applications in the area of distributed intelligent automation. PMID:28806756

Clean Water State Revolving Fund (CWSRF): Decentralized Wastewater Treatment

EPA Pesticide Factsheets

Decentralized wastewater treatment is an onsite or clustered system used to collect, treat, and disperse or reclaim wastewater from a small community or service area (e.g., septic systems, cluster systems, lagoons).

Redundant manipulator techniques for partially decentralized path planning and control of a platoon of autonomous vehicles.

PubMed

Stilwell, Daniel J; Bishop, Bradley E; Sylvester, Caleb A

2005-08-01

An approach to real-time trajectory generation for platoons of autonomous vehicles is developed from well-known control techniques for redundant robotic manipulators. The partially decentralized structure of this approach permits each vehicle to independently compute its trajectory in real-time using only locally generated information and low-bandwidth feedback generated by a system exogenous to the platoon. Our work is motivated by applications for which communications bandwidth is severely limited, such for platoons of autonomous underwater vehicles. The communication requirements for our trajectory generation approach are independent of the number of vehicles in the platoon, enabling platoons composed of a large number of vehicles to be coordinated despite limited communication bandwidth.

Assessing Location and Scale of Urban Nonpotable Water Reuse Systems for Life-Cycle Energy Consumption and Greenhouse Gas Emissions.

PubMed

Kavvada, Olga; Horvath, Arpad; Stokes-Draut, Jennifer R; Hendrickson, Thomas P; Eisenstein, William A; Nelson, Kara L

2016-12-20

Nonpotable water reuse (NPR) is one option for conserving valuable freshwater resources. Decentralization can improve distribution system efficiency by locating treatment closer to the consumer; however, small treatment systems may have higher unit energy and greenhouse-gas (GHG) emissions. This research explored the trade-off between residential NPR systems using a life-cycle approach to analyze the energy use and GHG emissions. Decentralized and centralized NPR options are compared to identify where decentralized systems achieve environmental advantages over centralized reuse alternatives, and vice versa, over a range of scales and spatial and demographic conditions. For high-elevation areas far from the centralized treatment plant, decentralized NPR could lower energy use by 29% and GHG emissions by 28%, but in low-elevation areas close to the centralized treatment plant, decentralized reuse could be higher by up to 85% (energy) and 49% (GHG emissions) for the scales assessed (20-2000 m 3 /day). Direct GHG emissions from the treatment processes were found to be highly uncertain and variable and were not included in the analysis. The framework presented can be used as a planning support tool to reveal the environmental impacts of integrating decentralized NPR with existing centralized wastewater infrastructure and can be adapted to evaluate different treatment technology scales for reuse.

Decentralized Bayesian search using approximate dynamic programming methods.

PubMed

Zhao, Yijia; Patek, Stephen D; Beling, Peter A

2008-08-01

We consider decentralized Bayesian search problems that involve a team of multiple autonomous agents searching for targets on a network of search points operating under the following constraints: 1) interagent communication is limited; 2) the agents do not have the opportunity to agree in advance on how to resolve equivalent but incompatible strategies; and 3) each agent lacks the ability to control or predict with certainty the actions of the other agents. We formulate the multiagent search-path-planning problem as a decentralized optimal control problem and introduce approximate dynamic heuristics that can be implemented in a decentralized fashion. After establishing some analytical properties of the heuristics, we present computational results for a search problem involving two agents on a 5 x 5 grid.

Energy Management System Successful in Indiana Elementary School.

ERIC Educational Resources Information Center

School Business Affairs, 1984

1984-01-01

The new Oregon-Davis Elementary School in rural Indiana embodies state-of-the-art energy management. Its environmental systems include thorough insulation, dual heating and cooling equipment for flexible loads, and decentralized computer controls. A heat recovery unit and variable-air-volume discharge ducts also contribute to conservation. (MCG)

Human-Guided Management of Collaborating Unmanned Vehicles in Degraded Communication Environments

DTIC Science & Technology

2010-05-01

system operated by the U.S. Air Force exemplifies the utility of unmanned systems. Predator drones have been employed extensively in intelligence...Massachusetts, USA), 2005. [50] Flint, M., T. Khobanova, and M. Curry , “Decentralized control using global optimization,” in Pro- ceedings of the AIAA

A decentralized charging control strategy for plug-in electric vehicles to mitigate wind farm intermittency and enhance frequency regulation

NASA Astrophysics Data System (ADS)

Luo, Xiao; Xia, Shiwei; Chan, Ka Wing

2014-02-01

This paper proposes a decentralized charging control strategy for a large population of plug-in electric vehicles (PEVs) to neutralize wind power fluctuations so as to improve the regulation of system frequency. Without relying on a central control entity, each PEV autonomously adjusts its charging or discharging power in response to a communal virtual price signal and based on its own urgency level of charging. Simulation results show that under the proposed charging control, the aggregate PEV power can effectively neutralize wind power fluctuations in real-time while differential allocation of neutralization duties among the PEVs can be realized to meet the PEV users' charging requirements. Also, harmful wind-induced cyclic operations in thermal units can be mitigated. As shown in economic analysis, the proposed strategy can create cost saving opportunities for both PEV users and utility.

Intraocular lens design for treating high myopia based on individual eye model

NASA Astrophysics Data System (ADS)

Wang, Yang; Wang, Zhaoqi; Wang, Yan; Zuo, Tong

2007-02-01

In this research, we firstly design the phakic intraocular lens (PIOL) based on individual eye model with optical design software ZEMAX. The individual PIOL is designed to correct the defocus and astigmatism, and then we compare the PIOL power calculated from the individual eye model with that from the experiential formula. Close values of PIOL power are obtained between the individual eye model and the formula, but the suggested method has more accuracy with more functions. The impact of PIOL decentration on human eye is evaluated, including rotation decentration, flat axis decentration, steep axis decentration and axial movement of PIOL, which is impossible with traditional method. To control the PIOL decentration errors, we give the limit values of PIOL decentration for the specific eye in this study.

Wave scheduling - Decentralized scheduling of task forces in multicomputers

NASA Technical Reports Server (NTRS)

Van Tilborg, A. M.; Wittie, L. D.

1984-01-01

Decentralized operating systems that control large multicomputers need techniques to schedule competing parallel programs called task forces. Wave scheduling is a probabilistic technique that uses a hierarchical distributed virtual machine to schedule task forces by recursively subdividing and issuing wavefront-like commands to processing elements capable of executing individual tasks. Wave scheduling is highly resistant to processing element failures because it uses many distributed schedulers that dynamically assign scheduling responsibilities among themselves. The scheduling technique is trivially extensible as more processing elements join the host multicomputer. A simple model of scheduling cost is used by every scheduler node to distribute scheduling activity and minimize wasted processing capacity by using perceived workload to vary decentralized scheduling rules. At low to moderate levels of network activity, wave scheduling is only slightly less efficient than a central scheduler in its ability to direct processing elements to accomplish useful work.

A Decentralized Framework for Multi-Agent Robotic Systems

PubMed Central

2018-01-01

Over the past few years, decentralization of multi-agent robotic systems has become an important research area. These systems do not depend on a central control unit, which enables the control and assignment of distributed, asynchronous and robust tasks. However, in some cases, the network communication process between robotic agents is overlooked, and this creates a dependency for each agent to maintain a permanent link with nearby units to be able to fulfill its goals. This article describes a communication framework, where each agent in the system can leave the network or accept new connections, sending its information based on the transfer history of all nodes in the network. To this end, each agent needs to comply with four processes to participate in the system, plus a fifth process for data transfer to the nearest nodes that is based on Received Signal Strength Indicator (RSSI) and data history. To validate this framework, we use differential robotic agents and a monitoring agent to generate a topological map of an environment with the presence of obstacles. PMID:29389849

Modeling and control of flexible space platforms with articulated payloads

NASA Technical Reports Server (NTRS)

Graves, Philip C.; Joshi, Suresh M.

1989-01-01

The first steps in developing a methodology for spacecraft control-structure interaction (CSI) optimization are identification and classification of anticipated missions, and the development of tractable mathematical models in each mission class. A mathematical model of a generic large flexible space platform (LFSP) with multiple independently pointed rigid payloads is considered. The objective is not to develop a general purpose numerical simulation, but rather to develop an analytically tractable mathematical model of such composite systems. The equations of motion for a single payload case are derived, and are linearized about zero steady-state. The resulting model is then extended to include multiple rigid payloads, yielding the desired analytical form. The mathematical models developed clearly show the internal inertial/elastic couplings, and are therefore suitable for analytical and numerical studies. A simple decentralized control law is proposed for fine pointing the payloads and LFSP attitude control, and simulation results are presented for an example problem. The decentralized controller is shown to be adequate for the example problem chosen, but does not, in general, guarantee stability. A centralized dissipative controller is then proposed, requiring a symmetric form of the composite system equations. Such a controller guarantees robust closed loop stability despite unmodeled elastic dynamics and parameter uncertainties.

Decentralized control of units in smart grids for the support of renewable energy supply

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sonnenschein, Michael, E-mail: Michael.Sonnenschein@Uni-Oldenburg.DE; Lünsdorf, Ontje, E-mail: Ontje.Luensdorf@OFFIS.DE; Bremer, Jörg, E-mail: Joerg.Bremer@Uni-Oldenburg.DE

Due to the significant environmental impact of power production from fossil fuels and nuclear fission, future energy systems will increasingly rely on distributed and renewable energy sources (RES). The electrical feed-in from photovoltaic (PV) systems and wind energy converters (WEC) varies greatly both over short and long time periods (from minutes to seasons), and (not only) by this effect the supply of electrical power from RES and the demand for electrical power are not per se matching. In addition, with a growing share of generation capacity especially in distribution grids, the top-down paradigm of electricity distribution is gradually replaced bymore » a bottom-up power supply. This altogether leads to new problems regarding the safe and reliable operation of power grids. In order to address these challenges, the notion of Smart Grids has been introduced. The inherent flexibilities, i.e. the set of feasible power schedules, of distributed power units have to be controlled in order to support demand–supply matching as well as stable grid operation. Controllable power units are e.g. combined heat and power plants, power storage systems such as batteries, and flexible power consumers such as heat pumps. By controlling the flexibilities of these units we are particularly able to optimize the local utilization of RES feed-in in a given power grid by integrating both supply and demand management measures with special respect to the electrical infrastructure. In this context, decentralized systems, autonomous agents and the concept of self-organizing systems will become key elements of the ICT based control of power units. In this contribution, we first show how a decentralized load management system for battery charging/discharging of electrical vehicles (EVs) can increase the locally used share of supply from PV systems in a low voltage grid. For a reliable demand side management of large sets of appliances, dynamic clustering of these appliances into uniformly controlled appliance sets is necessary. We introduce a method for self-organized clustering for this purpose and show how control of such clusters can affect load peaks in distribution grids. Subsequently, we give a short overview on how we are going to expand the idea of self-organized clusters of units into creating a virtual control center for dynamic virtual power plants (DVPP) offering products at a power market. For an efficient organization of DVPPs, the flexibilities of units have to be represented in a compact and easy to use manner. We give an introduction how the problem of representing a set of possibly 10{sup 100} feasible schedules can be solved by a machine-learning approach. In summary, this article provides an overall impression how we use agent based control techniques and methods of self-organization to support the further integration of distributed and renewable energy sources into power grids and energy markets. - Highlights: • Distributed load management for electrical vehicles supports local supply from PV. • Appliances can self-organize into so called virtual appliances for load control. • Dynamic VPPs can be controlled by extensively decentralized control centers. • Flexibilities of units can efficiently be represented by support-vector descriptions.« less

Decentralized control algorithms of a group of vehicles in 2D space

NASA Astrophysics Data System (ADS)

Pshikhopov, V. K.; Medvedev, M. Y.; Fedorenko, R. V.; Gurenko, B. V.

2017-02-01

The problem of decentralized control of group of robots, described by kinematic and dynamic equations of motion in the plane, is considered. Group performs predetermined rectangular area passing at a fixed speed, keeping the line and a uniform distribution. The environment may contain a priori unknown moving or stationary obstacles. Decentralized control algorithms, based on the formation of repellers in the state space of robots, are proposed. These repellers form repulsive forces generated by dynamic subsystems that extend the state space of robots. These repulsive forces are dynamic functions of distances and velocities of robots in the area of operation of the group. The process of formation of repellers allows to take into account the dynamic properties of robots, such as the maximum speed and acceleration. The robots local control law formulas are derived based on positionally-trajectory control method, which allows to operate with non-linear models. Lyapunov function in the form of a quadratic function of the state variables is constructed to obtain a nonlinear closed-loop control system. Due to the fact that a closed system is decomposed into two independent subsystems Lyapunov function is also constructed as two independent functions. Numerical simulation of the motion of a group of five robots is presented. In this simulation obstacles are presented by the boundaries of working area and a movable object of a given radius, moving rectilinear and uniform. Obstacle speed is comparable to the speeds of the robots in a group. The advantage of the proposed method is ensuring the stability of the trajectories and consideration of the limitations on the speed and acceleration at the trajectory planning stage. Proposed approach can be used for more general robots' models, including robots in the three-dimensional environment.

Decentralized Modular Systems Versus Centralized Systems.

ERIC Educational Resources Information Center

Crossey, R. E.

Building design, planning, and construction programing for modular decentralized mechanical building systems are outlined in terms of costs, performance, expansion and flexibility. Design strategy, approach, and guidelines for implementing such systems for buildings are suggested, with emphasis on mechanical equipment and building element…

Coordination of Distributed Fuzzy Behaviors in Mobile Robot Control

NASA Technical Reports Server (NTRS)

Tunstel, E.

1995-01-01

This presentation describes an approach to behavior coordination and conflict resolution within the context of a hierarchical architecture of fuzzy behaviors. Coordination is achieved using weighted decision-making based on behavioral degrees of applicability. This strategy is appropriate for fuzzy control of systems that can be represented by hierarchical or decentralized structures.

Decentralized and Tactical Air Traffic Flow Management

NASA Technical Reports Server (NTRS)

Odoni, Amedeo R.; Bertsimas, Dimitris

1997-01-01

This project dealt with the following topics: 1. Review and description of the existing air traffic flow management system (ATFM) and identification of aspects with potential for improvement. 2. Identification and review of existing models and simulations dealing with all system segments (enroute, terminal area, ground) 3. Formulation of concepts for overall decentralization of the ATFM system, ranging from moderate decentralization to full decentralization 4. Specification of the modifications to the ATFM system required to accommodate each of the alternative concepts. 5. Identification of issues that need to be addressed with regard to: determination of the way the ATFM system would be operating; types of flow management strategies that would be used; and estimation of the effectiveness of ATFM with regard to reducing delay and re-routing costs. 6. Concept evaluation through identification of criteria and methodologies for accommodating the interests of stakeholders and of approaches to optimization of operational procedures for all segments of the ATFM system.

Theoretical Perspectives on School District Decentralization.

ERIC Educational Resources Information Center

O'Shea, David

Drawing largely on data from Los Angeles, but with reference to other cities where appropriate, this paper attempts to clarify the distinctive positions taken by advocates of community control as opposed to proponents of administrative decentralization. While community control is essentially a political demand, oriented toward citizens influencing…

32 CFR Appendix B to Part 324 - System of Records Notice

Code of Federal Regulations, 2013 CFR

2013-07-01

... organizationally decentralized system, describe each level of organization or element that maintains a portion of... manager should be indicated. For geographically separated or organizationally decentralized activities...

32 CFR Appendix B to Part 324 - System of Records Notice

Code of Federal Regulations, 2011 CFR

2011-07-01

... organizationally decentralized system, describe each level of organization or element that maintains a portion of... manager should be indicated. For geographically separated or organizationally decentralized activities...

32 CFR Appendix B to Part 324 - System of Records Notice

Code of Federal Regulations, 2012 CFR

2012-07-01

... organizationally decentralized system, describe each level of organization or element that maintains a portion of... manager should be indicated. For geographically separated or organizationally decentralized activities...

32 CFR Appendix B to Part 324 - System of Records Notice

Code of Federal Regulations, 2014 CFR

2014-07-01

... organizationally decentralized system, describe each level of organization or element that maintains a portion of... manager should be indicated. For geographically separated or organizationally decentralized activities...

Decentralized Estimation and Vision-based Guidance of Fast Autonomous Systems with Guaranteed Performance in Uncertain Environments

DTIC Science & Technology

2013-04-22

Following for Unmanned Aerial Vehicles Using L1 Adaptive Augmentation of Commercial Autopilots, Journal of Guidance, Control, and Dynamics, (3 2010): 0...Naira Hovakimyan. L1 Adaptive Controller for MIMO system with Unmatched Uncertainties using Modi?ed Piecewise Constant Adaptation Law, IEEE 51st...adaptive input nominal input with  Nominal input L1 ‐based control generator  This L1 adaptive control architecture uses data from the reference model

Relationships between digital signal processing and control and estimation theory

NASA Technical Reports Server (NTRS)

Willsky, A. S.

1978-01-01

Research directions in the fields of digital signal processing and modern control and estimation theory are discussed. Stability theory, linear prediction and parameter identification, system synthesis and implementation, two-dimensional filtering, decentralized control and estimation, and image processing are considered in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the disciplines.

Reconfigurable Software for Controlling Formation Flying

NASA Technical Reports Server (NTRS)

Mueller, Joseph B.

2006-01-01

Software for a system to control the trajectories of multiple spacecraft flying in formation is being developed to reflect underlying concepts of (1) a decentralized approach to guidance and control and (2) reconfigurability of the control system, including reconfigurability of the software and of control laws. The software is organized as a modular network of software tasks. The computational load for both determining relative trajectories and planning maneuvers is shared equally among all spacecraft in a cluster. The flexibility and robustness of the software are apparent in the fact that tasks can be added, removed, or replaced during flight. In a computational simulation of a representative formation-flying scenario, it was demonstrated that the following are among the services performed by the software: Uploading of commands from a ground station and distribution of the commands among the spacecraft, Autonomous initiation and reconfiguration of formations, Autonomous formation of teams through negotiations among the spacecraft, Working out details of high-level commands (e.g., shapes and sizes of geometrically complex formations), Implementation of a distributed guidance law providing autonomous optimization and assignment of target states, and Implementation of a decentralized, fuel-optimal, impulsive control law for planning maneuvers.

DAISY-DAMP: A distributed AI system for the dynamic allocation and management of power

NASA Technical Reports Server (NTRS)

Hall, Steven B.; Ohler, Peter C.

1988-01-01

One of the critical parameters that must be addressed when designing a loosely coupled Distributed AI SYstem (DAISY) has to do with the degree to which authority is centralized or decentralized. The decision to implement the Dynamic Allocation and Management of Power (DAMP) system as a network of cooperating agents mandated this study. The DAISY-DAMP problem is described; the component agents of the system are characterized; and the communication protocols system elucidated. The motivations and advantages in designing the system with authority decentralized is discussed. Progress in the area of Speech Act theory is proposed as playing a role in constructing decentralized systems.

Leadership and the Decentralized Control of Schools

ERIC Educational Resources Information Center

Steinberg, Matthew P.

2013-01-01

This review examines the literature related to leadership and the decentralized control of schools. It first considers the distinctive goals of public and private agencies, the specific constraints that shape the autonomy of leaders in different sectors, and the ways in which new models of public management are infusing public agencies with…

How changing quality management influenced PGME accreditation: a focus on decentralization and quality improvement.

PubMed

Akdemir, Nesibe; Lombarts, Kiki M J M H; Paternotte, Emma; Schreuder, Bas; Scheele, Fedde

2017-06-02

Evaluating the quality of postgraduate medical education (PGME) programs through accreditation is common practice worldwide. Accreditation is shaped by educational quality and quality management. An appropriate accreditation design is important, as it may drive improvements in training. Moreover, accreditors determine whether a PGME program passes the assessment, which may have major consequences, such as starting, continuing or discontinuing PGME. However, there is limited evidence for the benefits of different choices in accreditation design. Therefore, this study aims to explain how changing views on educational quality and quality management have impacted the design of the PGME accreditation system in the Netherlands. To determine the historical development of the Dutch PGME accreditation system, we conducted a document analysis of accreditation documents spanning the past 50 years and a vision document outlining the future system. A template analysis technique was used to identify the main elements of the system. Four themes in the Dutch PGME accreditation system were identified: (1) objectives of accreditation, (2) PGME quality domains, (3) quality management approaches and (4) actors' responsibilities. Major shifts have taken place regarding decentralization, residency performance and physician practice outcomes, and quality improvement. Decentralization of the responsibilities of the accreditor was absent in 1966, but this has been slowly changing since 1999. In the future system, there will be nearly a maximum degree of decentralization. A focus on outcomes and quality improvement has been introduced in the current system. The number of formal documents striving for quality assurance has increased enormously over the past 50 years, which has led to increased bureaucracy. The future system needs to decrease the number of standards to focus on measurable outcomes and to strive for quality improvement. The challenge for accreditors is to find the right balance between trusting and controlling medical professionals. Their choices will be reflected in the accreditation design. The four themes could enhance international comparisons and encourage better choices in the design of accreditation systems.

Different approaches for centralized and decentralized water system management in multiple decision makers' problems

NASA Astrophysics Data System (ADS)

Anghileri, D.; Giuliani, M.; Castelletti, A.

2012-04-01

There is a general agreement that one of the most challenging issues related to water system management is the presence of many and often conflicting interests as well as the presence of several and independent decision makers. The traditional approach to multi-objective water systems management is a centralized management, in which an ideal central regulator coordinates the operation of the whole system, exploiting all the available information and balancing all the operating objectives. Although this approach allows to obtain Pareto-optimal solutions representing the maximum achievable benefit, it is based on assumptions which strongly limits its application in real world contexts: 1) top-down management, 2) existence of a central regulation institution, 3) complete information exchange within the system, 4) perfect economic efficiency. A bottom-up decentralized approach seems therefore to be more suitable for real case applications since different reservoir operators may maintain their independence. In this work we tested the consequences of a change in the water management approach moving from a centralized toward a decentralized one. In particular we compared three different cases: the centralized management approach, the independent management approach where each reservoir operator takes the daily release decision maximizing (or minimizing) his operating objective independently from each other, and an intermediate approach, leading to the Nash equilibrium of the associated game, where different reservoir operators try to model the behaviours of the other operators. The three approaches are demonstrated using a test case-study composed of two reservoirs regulated for the minimization of flooding in different locations. The operating policies are computed by solving one single multi-objective optimal control problem, in the centralized management approach; multiple single-objective optimization problems, i.e. one for each operator, in the independent case; using techniques related to game theory for the description of the interaction between the two operators, in the last approach. Computational results shows that the Pareto-optimal control policies obtained in the centralized approach dominate the control policies of both the two cases of decentralized management and that the so called price of anarchy increases moving toward the independent management approach. However, the Nash equilibrium solution seems to be the most promising alternative because it represents a good compromise in maximizing management efficiency without limiting the behaviours of the reservoir operators.

Ophiuroid robot that self-organizes periodic and non-periodic arm movements.

PubMed

Kano, Takeshi; Suzuki, Shota; Watanabe, Wataru; Ishiguro, Akio

2012-09-01

Autonomous decentralized control is a key concept for understanding the mechanism underlying adaptive and versatile locomotion of animals. Although the design of an autonomous decentralized control system that ensures adaptability by using coupled oscillators has been proposed previously, it cannot comprehensively reproduce the versatility of animal behaviour. To tackle this problem, we focus on using ophiuroids as a simple model that exhibits versatile locomotion including periodic and non-periodic arm movements. Our existing model for ophiuroid locomotion uses an active rotator model that describes both oscillatory and excitatory properties. In this communication, we develop an ophiuroid robot to confirm the validity of this proposed model in the real world. We show that the robot travels by successfully coordinating periodic and non-periodic arm movements in response to external stimuli.

Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

PubMed

Zhao, Bo; Li, Chenghao; Liu, Derong; Li, Yuanchun

2015-01-01

This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations.

Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure

PubMed Central

Zhao, Bo; Li, Yuanchun

2015-01-01

This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations. PMID:26181826

The Paradox of Decentralizing Schools: Lessons from Business, Government, and the Catholic Church.

ERIC Educational Resources Information Center

Murphy, Jerome T.

1989-01-01

By the year 2000, school decentralization could become another unfortunate, ineffectual pendulum swing. According to this article, a dynamic, ever-changing system of decentralization and centralization balances the benefits of local administrative autonomy with the pursuit of unified goals and helps each leadership level understand its…

Cooperative control theory and integrated flight and propulsion control

NASA Technical Reports Server (NTRS)

Schmidt, David K.; Schierman, John D.

1995-01-01

The major contribution of this research was the exposition of the fact that airframe and engine interactions could be present, and their effects could include loss of stability and performance of the control systems. Also, the significance of two directional, as opposed to one-directional, coupling was identified and explained. A multivariable stability and performance analysis methodology was developed, and applied to several candidate aircraft configurations. In these example evaluations, the significance of these interactions was underscored. Also exposed was the fact that with interactions present along with some integrated control approaches, the engine command/limiting logic (which represents an important nonlinear component of the engine control system) can impact closed-loop airframe/engine system stability. Finally, a brief investigation of control-law synthesis techniques appropriate for the class of systems was pursued, and it was determined that multivariable techniques, including model-following formulations of LQG and/or H infinity methods, showed promise. However, for practical reasons, decentralized control architectures are preferred, which is an architecture incompatible with these synthesis methods. The major contributions of the second phase of the grant was the development of conditions under which no decentralized controller could achieve closed loop system requirements on stability and/or performance. Sought were conditions that depended only on properties of the plant and the requirement, and independent of any particular control law or synthesis approach. Therefore, they could be applied a priori, before synthesis of a candidate control law. Under this grant, such conditions were found regarding stability, and encouraging initial results were obtained regarding performance.

Using Systems Theory to Examine Patient and Nurse Structures, Processes, and Outcomes in Centralized and Decentralized Units.

PubMed

Real, Kevin; Fay, Lindsey; Isaacs, Kathy; Carll-White, Allison; Schadler, Aric

2018-01-01

This study utilizes systems theory to understand how changes to physical design structures impact communication processes and patient and staff design-related outcomes. Many scholars and researchers have noted the importance of communication and teamwork for patient care quality. Few studies have examined changes to nursing station design within a systems theory framework. This study employed a multimethod, before-and-after, quasi-experimental research design. Nurses completed surveys in centralized units and later in decentralized units ( N = 26 pre , N = 51 post ). Patients completed surveys ( N = 62 pre ) in centralized units and later in decentralized units ( N = 49 post ). Surveys included quantitative measures and qualitative open-ended responses. Patients preferred the decentralized units because of larger single-occupancy rooms, greater privacy/confidentiality, and overall satisfaction with design. Nurses had a more complex response. Nurses approved the patient rooms, unit environment, and noise levels in decentralized units. However, they reported reduced access to support spaces, lower levels of team/mentoring communication, and less satisfaction with design than in centralized units. Qualitative findings supported these results. Nurses were more positive about centralized units and patients were more positive toward decentralized units. The results of this study suggest a need to understand how system components operate in concert. A major contribution of this study is the inclusion of patient satisfaction with design, an important yet overlooked fact in patient satisfaction. Healthcare design researchers and practitioners may consider how changing system interdependencies can lead to unexpected changes to communication processes and system outcomes in complex systems.

Decentralized Multisensory Information Integration in Neural Systems.

PubMed

Zhang, Wen-Hao; Chen, Aihua; Rasch, Malte J; Wu, Si

2016-01-13

How multiple sensory cues are integrated in neural circuitry remains a challenge. The common hypothesis is that information integration might be accomplished in a dedicated multisensory integration area receiving feedforward inputs from the modalities. However, recent experimental evidence suggests that it is not a single multisensory brain area, but rather many multisensory brain areas that are simultaneously involved in the integration of information. Why many mutually connected areas should be needed for information integration is puzzling. Here, we investigated theoretically how information integration could be achieved in a distributed fashion within a network of interconnected multisensory areas. Using biologically realistic neural network models, we developed a decentralized information integration system that comprises multiple interconnected integration areas. Studying an example of combining visual and vestibular cues to infer heading direction, we show that such a decentralized system is in good agreement with anatomical evidence and experimental observations. In particular, we show that this decentralized system can integrate information optimally. The decentralized system predicts that optimally integrated information should emerge locally from the dynamics of the communication between brain areas and sheds new light on the interpretation of the connectivity between multisensory brain areas. To extract information reliably from ambiguous environments, the brain integrates multiple sensory cues, which provide different aspects of information about the same entity of interest. Here, we propose a decentralized architecture for multisensory integration. In such a system, no processor is in the center of the network topology and information integration is achieved in a distributed manner through reciprocally connected local processors. Through studying the inference of heading direction with visual and vestibular cues, we show that the decentralized system can integrate information optimally, with the reciprocal connections between processers determining the extent of cue integration. Our model reproduces known multisensory integration behaviors observed in experiments and sheds new light on our understanding of how information is integrated in the brain. Copyright © 2016 Zhang et al.

Decentralized Multisensory Information Integration in Neural Systems

PubMed Central

Zhang, Wen-hao; Chen, Aihua

2016-01-01

How multiple sensory cues are integrated in neural circuitry remains a challenge. The common hypothesis is that information integration might be accomplished in a dedicated multisensory integration area receiving feedforward inputs from the modalities. However, recent experimental evidence suggests that it is not a single multisensory brain area, but rather many multisensory brain areas that are simultaneously involved in the integration of information. Why many mutually connected areas should be needed for information integration is puzzling. Here, we investigated theoretically how information integration could be achieved in a distributed fashion within a network of interconnected multisensory areas. Using biologically realistic neural network models, we developed a decentralized information integration system that comprises multiple interconnected integration areas. Studying an example of combining visual and vestibular cues to infer heading direction, we show that such a decentralized system is in good agreement with anatomical evidence and experimental observations. In particular, we show that this decentralized system can integrate information optimally. The decentralized system predicts that optimally integrated information should emerge locally from the dynamics of the communication between brain areas and sheds new light on the interpretation of the connectivity between multisensory brain areas. SIGNIFICANCE STATEMENT To extract information reliably from ambiguous environments, the brain integrates multiple sensory cues, which provide different aspects of information about the same entity of interest. Here, we propose a decentralized architecture for multisensory integration. In such a system, no processor is in the center of the network topology and information integration is achieved in a distributed manner through reciprocally connected local processors. Through studying the inference of heading direction with visual and vestibular cues, we show that the decentralized system can integrate information optimally, with the reciprocal connections between processers determining the extent of cue integration. Our model reproduces known multisensory integration behaviors observed in experiments and sheds new light on our understanding of how information is integrated in the brain. PMID:26758843

Digital signal processing and control and estimation theory -- Points of tangency, area of intersection, and parallel directions

NASA Technical Reports Server (NTRS)

Willsky, A. S.

1976-01-01

A number of current research directions in the fields of digital signal processing and modern control and estimation theory were studied. Topics such as stability theory, linear prediction and parameter identification, system analysis and implementation, two-dimensional filtering, decentralized control and estimation, image processing, and nonlinear system theory were examined in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the two disciplines. An extensive bibliography is included.

Decentralized Adaptive Control For Robots

NASA Technical Reports Server (NTRS)

Seraji, Homayoun

1989-01-01

Precise knowledge of dynamics not required. Proposed scheme for control of multijointed robotic manipulator calls for independent control subsystem for each joint, consisting of proportional/integral/derivative feedback controller and position/velocity/acceleration feedforward controller, both with adjustable gains. Independent joint controller compensates for unpredictable effects, gravitation, and dynamic coupling between motions of joints, while forcing joints to track reference trajectories. Scheme amenable to parallel processing in distributed computing system wherein each joint controlled by relatively simple algorithm on dedicated microprocessor.

Decentralized adaptive control

NASA Technical Reports Server (NTRS)

Oh, B. J.; Jamshidi, M.; Seraji, H.

1988-01-01

A decentralized adaptive control is proposed to stabilize and track the nonlinear, interconnected subsystems with unknown parameters. The adaptation of the controller gain is derived by using model reference adaptive control theory based on Lyapunov's direct method. The adaptive gains consist of sigma, proportional, and integral combination of the measured and reference values of the corresponding subsystem. The proposed control is applied to the joint control of a two-link robot manipulator, and the performance in computer simulation corresponds with what is expected in theoretical development.

Decentralizing Maternity Services to Increase Skilled Attendance at Birth and Antenatal Care Utilization in Rural Rwanda: A Prospective Cohort Study

PubMed Central

Nathan, Lisa M.; Shi, Quihu; Plewniak, Kari; Zhang, Charles; Nsabimana, Damien; Sklar, Marc; Mutimura, Eugene; Merkatz, Irwin R.; Einstein, Mark H.; Anastos, Kathryn

2015-01-01

To evaluate the effectiveness of decentralizing ambulatory reproductive and intrapartum services to increase rates of antenatal care (ANC) utilization and skilled attendance at birth (SAB) in Rwanda. A prospective cohort study was implemented with one control and two intervention sites: decentralized ambulatory reproductive healthcare and decentralized intrapartum care. Multivariate logistic regression analysis was performed with primary outcome of lack of SAB and secondary outcome of ≥3 ANC visits. 536 women were entered in the study. Distance lived from delivery site significantly predicted SAB (p = 0.007), however distance lived to ANC site did not predict ≥3 ANC visits (p = 0.81). Neither decentralization of ambulatory reproductive healthcare (p = 0.10) nor intrapartum care (p = 0.40) was significantly associated with SAB. The control site had the greatest percentage of women receive ≥3 ANC visits (p < 0.001). Receiving <3 ANC visits was associated with a 3.98 times greater odds of not having SAB (p = 0.001). No increase in adverse outcomes was found with decentralization of ambulatory reproductive health care or intrapartum care. The factors that predict utilization of physically accessible services in rural Africa are complex. Decentralization of services may be one strategy to increase rates of SAB and ANC utilization, but selection biases may have precluded accurate analysis. Efforts to increase ANC utilization may be a worthwhile investment to increase SAB. PMID:25652061

Space shuttle program information control and retrieval system feasibility study report

NASA Technical Reports Server (NTRS)

Lingle, C. P.

1973-01-01

The feasibility of having a common information management network for space shuttle data, is studied. Identified are the information types required, sources and users of the information, and existing techniques for acquiring, storing and retrieving the data. The study concluded that a decentralized system is feasible, and described a recommended development plan for it.

Decentralization in Zambia: resource allocation and district performance.

PubMed

Bossert, Thomas; Chitah, Mukosha Bona; Bowser, Diana

2003-12-01

Zambia implemented an ambitious process of health sector decentralization in the mid 1990s. This article presents an assessment of the degree of decentralization, called 'decision space', that was allowed to districts in Zambia, and an analysis of data on districts available at the national level to assess allocation choices made by local authorities and some indicators of the performance of the health systems under decentralization. The Zambian officials in health districts had a moderate range of choice over expenditures, user fees, contracting, targeting and governance. Their choices were quite limited over salaries and allowances and they did not have control over additional major sources of revenue, like local taxes. The study found that the formula for allocation of government funding which was based on population size and hospital beds resulted in relatively equal per capita expenditures among districts. Decentralization allowed the districts to make decisions on internal allocation of resources and on user fee levels and expenditures. General guidelines for the allocation of resources established a maximum and minimum percentage to be allocated to district offices, hospitals, health centres and communities. Districts tended to exceed the maximum for district offices, but the large urban districts and those without public district hospitals were not even reaching the minimum for hospital allocations. Wealthier and urban districts were more successful in raising revenue through user fees, although the proportion of total expenditures that came from user fees was low. An analysis of available indicators of performance, such as the utilization of health services, immunization coverage and family planning activities, found little variation during the period 1995-98 except for a decline in immunization coverage, which may have also been affected by changes in donor funding. These findings suggest that decentralization may not have had either a positive or negative impact on services.

Electric Water Heater Modeling and Control Strategies for Demand Response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diao, Ruisheng; Lu, Shuai; Elizondo, Marcelo A.

2012-07-22

Abstract— Demand response (DR) has a great potential to provide balancing services at normal operating conditions and emergency support when a power system is subject to disturbances. Effective control strategies can significantly relieve the balancing burden of conventional generators and reduce investment on generation and transmission expansion. This paper is aimed at modeling electric water heaters (EWH) in households and tests their response to control strategies to implement DR. The open-loop response of EWH to a centralized signal is studied by adjusting temperature settings to provide regulation services; and two types of decentralized controllers are tested to provide frequency supportmore » following generator trips. EWH models are included in a simulation platform in DIgSILENT to perform electromechanical simulation, which contains 147 households in a distribution feeder. Simulation results show the dependence of EWH response on water heater usage . These results provide insight suggestions on the need of control strategies to achieve better performance for demand response implementation. Index Terms— Centralized control, decentralized control, demand response, electrical water heater, smart grid« less

A decentralized approach to reducing the social costs of cascading failures

NASA Astrophysics Data System (ADS)

Hines, Paul

Large cascading failures in electrical power networks come with enormous social costs. These can be direct financial costs, such as the loss of refrigerated foods in grocery stores, or more indirect social costs, such as the traffic congestion that results from the failure of traffic signals. While engineers and policy makers have made numerous technical and organizational changes to reduce the frequency and impact of large cascading failures, the existing data, as described in Chapter 2 of this work, indicate that the overall frequency and impact of large electrical blackouts in the United States are not decreasing. Motivated by the cascading failure problem, this thesis describes a new method for Distributed Model Predictive Control and a power systems application. The central goal of the method, when applied to power systems, is to reduce the social costs of cascading failures by making small, targeted reductions in load and generation and changes to generator voltage set points. Unlike some existing schemes that operate from centrally located control centers, the method is operated by software agents located at substations distributed throughout the power network. The resulting multi-agent control system is a new approach to decentralized control, combining Distributed Model Predictive Control and Reciprocal Altruism. Experimental results indicate that this scheme can in fact decrease the average size, and thus social costs, of cascading failures. Over 100 randomly generated disturbances to a model of the IEEE 300 bus test network, the method resulted in nearly an order of magnitude decrease in average event size (measured in cost) relative to cascading failure simulations without remedial control actions. Additionally, the communication requirements for the method are measured, and found to be within the bandwidth capabilities of current communications technology (on the order of 100kB/second). Experiments on several resistor networks with varying structures, including a random graph, a scale-free network and a power grid indicate that the effectiveness of decentralized control schemes, like the method proposed here, is a function of the structure of the network that is to be controlled.

Future evolution of distributed systems for smart grid - The challenges and opportunities to using decentralized energy system

NASA Astrophysics Data System (ADS)

Konopko, Joanna

2015-12-01

A decentralized energy system is a relatively new approach in the power industry. Decentralized energy systems provide promising opportunities for deploying renewable energy sources locally available as well as for expanding access to clean energy services to remote communities. The electricity system of the future must produce and distribute electricity that is reliable and affordable. To accomplish these goals, both the electricity grid and the existing regulatory system must be smarter. In this paper, the major issues and challenges in distributed systems for smart grid are discussed and future trends are presented. The smart grid technologies and distributed generation systems are explored. A general overview of the comparison of the traditional grid and smart grid is also included.

A Closed-Loop Hardware Simulation of Decentralized Satellite Formation Control

NASA Technical Reports Server (NTRS)

Ebimuma, Takuji; Lightsey, E. Glenn; Baur, Frank (Technical Monitor)

2002-01-01

In recent years, there has been significant interest in the use of formation flying spacecraft for a variety of earth and space science missions. Formation flying may provide smaller and cheaper satellites that, working together, have more capability than larger and more expensive satellites. Several decentralized architectures have been proposed for autonomous establishment and maintenance of satellite formations. In such architectures, each satellite cooperatively maintains the shape of the formation without a central supervisor, and processing only local measurement information. The Global Positioning System (GPS) sensors are ideally suited to provide such local position and velocity measurements to the individual satellites. An investigation of the feasibility of a decentralized approach to satellite formation flying was originally presented by Carpenter. He extended a decentralized linear-quadratic-Gaussian (LQG) framework proposed by Speyer in a fashion similar to an extended Kalman filter (EKE) which processed GPS position fix solutions. The new decentralized LQG architecture was demonstrated in a numerical simulation for a realistic scenario that is similar to missions that have been proposed by NASA and the U.S. Air Force. Another decentralized architecture was proposed by Park et al. using carrier differential-phase GPS (CDGPS). Recently, Busse et al demonstrated the decentralized CDGPS architecture in a hardware-in-the-loop simulation on the Formation Flying TestBed (FFTB) at Goddard Space Flight Center (GSFC), which features two Spirent Cox 16 channel GPS signal generator. Although representing a step forward by utilizing GPS signal simulators for a spacecraft formation flying simulation, only an open-loop performance, in which no maneuvers were executed based on the real-time state estimates, was considered. In this research, hardware experimentation has been extended to include closed-loop integrated guidance and navigation of multiple spacecraft formations using GPS receivers and real-time vehicle telemetry. A hardware closed-loop simulation has been performed using the decentralized LQG architecture proposed by Carpenter in the GPS test facility at the Center for Space Research (CSR). This is the first presentation using this type of hardware for demonstration of closed-loop spacecraft formation flying.

Implementation of a decentralized community-based treatment program to improve the management of Buruli ulcer in the Ouinhi district of Benin, West Africa

PubMed Central

Amoussouhoui, Arnaud Setondji; Wadagni, Anita Carolle; Johnson, Roch Christian; Aoulou, Paulin; Agbo, Inès Elvire; Houezo, Jean-Gabin; Boyer, Micah; Nichter, Mark

2018-01-01

Background Mycobacterium ulcerans infection, commonly known as Buruli ulcer (BU), is a debilitating neglected tropical disease. Its management remains complex and has three main components: antibiotic treatment combining rifampicin and streptomycin for 56 days, wound dressings and skin grafts for large ulcerations, and physical therapy to prevent functional limitations after care. In Benin, BU patient care is being integrated into the government health system. In this paper, we report on an innovative pilot program designed to introduce BU decentralization in Ouinhi district, one of Benin’s most endemic districts previously served by centralized hospital-based care. Methodology/Principal findings We conducted intervention-oriented research implemented in four steps: baseline study, training of health district clinical staff, outreach education, outcome and impact assessments. Study results demonstrated that early BU lesions (71% of all detected cases) could be treated in the community following outreach education, and that most of the afflicted were willing to accept decentralized treatment. Ninety-three percent were successfully treated with antibiotics alone. The impact evaluation found that community confidence in decentralized BU care was greatly enhanced by clinic staff who came to be seen as having expertise in the care of most chronic wounds. Conclusions/Significance This study documents a successful BU outreach and decentralized care program reaching early BU cases not previously treated by a proactive centralized BU program. The pilot program further demonstrates the added value of integrated wound management for NTD control. PMID:29529087

Implementation of a decentralized community-based treatment program to improve the management of Buruli ulcer in the Ouinhi district of Benin, West Africa.

PubMed

Amoussouhoui, Arnaud Setondji; Sopoh, Ghislain Emmanuel; Wadagni, Anita Carolle; Johnson, Roch Christian; Aoulou, Paulin; Agbo, Inès Elvire; Houezo, Jean-Gabin; Boyer, Micah; Nichter, Mark

2018-03-01

Mycobacterium ulcerans infection, commonly known as Buruli ulcer (BU), is a debilitating neglected tropical disease. Its management remains complex and has three main components: antibiotic treatment combining rifampicin and streptomycin for 56 days, wound dressings and skin grafts for large ulcerations, and physical therapy to prevent functional limitations after care. In Benin, BU patient care is being integrated into the government health system. In this paper, we report on an innovative pilot program designed to introduce BU decentralization in Ouinhi district, one of Benin's most endemic districts previously served by centralized hospital-based care. We conducted intervention-oriented research implemented in four steps: baseline study, training of health district clinical staff, outreach education, outcome and impact assessments. Study results demonstrated that early BU lesions (71% of all detected cases) could be treated in the community following outreach education, and that most of the afflicted were willing to accept decentralized treatment. Ninety-three percent were successfully treated with antibiotics alone. The impact evaluation found that community confidence in decentralized BU care was greatly enhanced by clinic staff who came to be seen as having expertise in the care of most chronic wounds. This study documents a successful BU outreach and decentralized care program reaching early BU cases not previously treated by a proactive centralized BU program. The pilot program further demonstrates the added value of integrated wound management for NTD control.

A note on decentralized integral controllability

NASA Technical Reports Server (NTRS)

Nwokah, O. D. I.; Frazho, A. E.; Le, D. K.

1993-01-01

A concept of decentralized integral controllability (DIC) defined on a given gain space Phi is clarified and related to the original definition given by Morari and Zafirou (1989). This leads to a simple proof of the existence of DIC on Phi from which existence conditions for DIC can be routinely deduced in the sense of Morari and Zafirou.

Partitioning of centralized integrated flight/propulsion control design for decentralized implementation

NASA Technical Reports Server (NTRS)

Garg, Sanjay

1993-01-01

The notion of partitioning a centralized controller into a decentralized, hierarchical structure suitable for integrated flight/propulsion control (IFPC) implementation is discussed. A systematic procedure is developed for determining partitioned airframe and engine subsystem controllers (subcontrollers), with the desired interconnection structure, that approximate the closed-loop performance and robustness characteristics of a given centralized controller. The procedure is demonstrated by application to IFPC design for a short take-off and vertical landing (STOVL) aircraft in the landing-approach-to-hover-transition flight phase.

Vertical and Horizontal Forces: A Framework for Understanding Airpower Command and Control

DTIC Science & Technology

2014-05-22

failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ...ABSTRACT The Air Force has long maintained the tenet of “centralized control , decentralized execution.” Changes in the contextual environment and...help commanders understand how command and control (C2) systems work best today. The proposed cognitive framework moves beyond centralization

Threshold-Based Random Charging Scheme for Decentralized PEV Charging Operation in a Smart Grid.

PubMed

Kwon, Ojin; Kim, Pilkee; Yoon, Yong-Jin

2016-12-26

Smart grids have been introduced to replace conventional power distribution systems without real time monitoring for accommodating the future market penetration of plug-in electric vehicles (PEVs). When a large number of PEVs require simultaneous battery charging, charging coordination techniques have become one of the most critical factors to optimize the PEV charging performance and the conventional distribution system. In this case, considerable computational complexity of a central controller and exchange of real time information among PEVs may occur. To alleviate these problems, a novel threshold-based random charging (TBRC) operation for a decentralized charging system is proposed. Using PEV charging thresholds and random access rates, the PEVs themselves can participate in the charging requests. As PEVs with a high battery state do not transmit the charging requests to the central controller, the complexity of the central controller decreases due to the reduction of the charging requests. In addition, both the charging threshold and the random access rate are statistically calculated based on the average of supply power of the PEV charging system that do not require a real time update. By using the proposed TBRC with a tolerable PEV charging degradation, a 51% reduction of the PEV charging requests is achieved.

Threshold-Based Random Charging Scheme for Decentralized PEV Charging Operation in a Smart Grid

PubMed Central

Kwon, Ojin; Kim, Pilkee; Yoon, Yong-Jin

2016-01-01

Smart grids have been introduced to replace conventional power distribution systems without real time monitoring for accommodating the future market penetration of plug-in electric vehicles (PEVs). When a large number of PEVs require simultaneous battery charging, charging coordination techniques have become one of the most critical factors to optimize the PEV charging performance and the conventional distribution system. In this case, considerable computational complexity of a central controller and exchange of real time information among PEVs may occur. To alleviate these problems, a novel threshold-based random charging (TBRC) operation for a decentralized charging system is proposed. Using PEV charging thresholds and random access rates, the PEVs themselves can participate in the charging requests. As PEVs with a high battery state do not transmit the charging requests to the central controller, the complexity of the central controller decreases due to the reduction of the charging requests. In addition, both the charging threshold and the random access rate are statistically calculated based on the average of supply power of the PEV charging system that do not require a real time update. By using the proposed TBRC with a tolerable PEV charging degradation, a 51% reduction of the PEV charging requests is achieved. PMID:28035963

Federal Policy and Adolescent AIDS.

ERIC Educational Resources Information Center

Wilcox, Brian L.

1990-01-01

Maintains that federal policy on adolescent Acquired Immune Deficiency Syndrome health care and research is nonexistent or piecemeal. Despite the work of the Centers for Disease Control, efforts at preventive education are uncoordinated, resulting from the decentralized nature of the public health and education systems, and are hampered by social…

Neighborhood Team Policing: Prescriptive Package.

ERIC Educational Resources Information Center

Bloch, Peter B.; Specht, David

The manual for neighborhood team policing, a method of decentralizing police departments, presents guidelines for putting a team policing system into effect. Noticeable results of this type of this type organization have been an increased effectiveness in crime control, improved police-community relations, and improved police morale. Chapter 1…

Noise, cost and speed-accuracy trade-offs: decision-making in a decentralized system

PubMed Central

Marshall, James A.R.; Dornhaus, Anna; Franks, Nigel R.; Kovacs, Tim

2005-01-01

Many natural and artificial decision-making systems face decision problems where there is an inherent compromise between two or more objectives. One such common compromise is between the speed and accuracy of a decision. The ability to exploit the characteristics of a decision problem in order to vary between the extremes of making maximally rapid, or maximally accurate decisions, is a useful property of such systems. Colonies of the ant Temnothorax albipennis (formerly Leptothorax albipennis) are a paradigmatic decentralized decision-making system, and have been shown flexibly to compromise accuracy for speed when making decisions during house-hunting. During emigration, a colony must typically evaluate and choose between several possible alternative new nest sites of differing quality. In this paper, we examine this speed-accuracy trade-off through modelling, and conclude that noise and time-cost of assessing alternative choices are likely to be significant for T. albipennis. Noise and cost of such assessments are likely to mean that T. albipennis' decision-making mechanism is Pareto-optimal in one crucial regard; increasing the willingness of individuals to change their decisions cannot improve collective accuracy overall without impairing speed. We propose that a decentralized control algorithm based on this emigration behaviour may be derived for applications in engineering domains and specify the characteristics of the problems to which it should be suited, based on our new results. PMID:16849234

Malaria Distribution, Prevalence, Drug Resistance and Control in Indonesia

PubMed Central

Elyazar, Iqbal R.F.; Hay, Simon I.; Baird, J. Kevin

2011-01-01

Approximately 230 million people live in Indonesia. The country is also home to over 20 anopheline vectors of malaria which transmit all four of the species of Plasmodium that routinely infect humans. A complex mosaic of risk of infection across this 5000-km-long archipelago of thousands of islands and distinctive habitats seriously challenges efforts to control malaria. Social, economic and political dimensions contribute to these complexities. This chapter examines malaria and its control in Indonesia, from the earliest efforts by malariologists of the colonial Netherlands East Indies, through the Global Malaria Eradication Campaign of the 1950s, the tumult following the coup d’état of 1965, the global resurgence of malaria through the 1980s and 1990s and finally through to the decentralization of government authority following the fall of the authoritarian Soeharto regime in 1998. We detail important methods of control and their impact in the context of the political systems that supported them. We examine prospects for malaria control in contemporary decentralized and democratized Indonesia with multidrug-resistant malaria and greatly diminished capacities for integrated malaria control management programs. PMID:21295677

Decentralized real-time simulation of forest machines

NASA Astrophysics Data System (ADS)

Freund, Eckhard; Adam, Frank; Hoffmann, Katharina; Rossmann, Juergen; Kraemer, Michael; Schluse, Michael

2000-10-01

To develop realistic forest machine simulators is a demanding task. A useful simulator has to provide a close- to-reality simulation of the forest environment as well as the simulation of the physics of the vehicle. Customers demand a highly realistic three dimensional forestry landscape and the realistic simulation of the complex motion of the vehicle even in rough terrain in order to be able to use the simulator for operator training under close-to- reality conditions. The realistic simulation of the vehicle, especially with the driver's seat mounted on a motion platform, greatly improves the effect of immersion into the virtual reality of a simulated forest and the achievable level of education of the driver. Thus, the connection of the real control devices of forest machines to the simulation system has to be supported, i.e. the real control devices like the joysticks or the board computer system to control the crane, the aggregate etc. Beyond, the fusion of the board computer system and the simulation system is realized by means of sensors, i.e. digital and analog signals. The decentralized system structure allows several virtual reality systems to evaluate and visualize the information of the control devices and the sensors. So, while the driver is practicing, the instructor can immerse into the same virtual forest to monitor the session from his own viewpoint. In this paper, we are describing the realized structure as well as the necessary software and hardware components and application experiences.

Vocational Training in Chile: A Decentralized and Market Oriented System. Training Policy Study No. 8.

ERIC Educational Resources Information Center

Espinoza, Eduardo Martinez

From 1976 to 1983 major reforms were enacted in Chile in the vocational training systems, based on four principles: decentralization, integration, diversification, and participation. The vocational training system in Chile is a legally established, market-oriented system in which many private training agencies compete to sell their services to…

Decentralizing the "Future Planning" of Public Education. Project SIMU School: Santa Clara County Component.

ERIC Educational Resources Information Center

Candoli, I. C.; Leu, Donald J.

This analysis draws on a variety of experiences with and models of centralized and decentralized school systems now in existence. The decentralized model or profile posed for consideration is intended as a basis for the development of a process by which indigenous models can be established for any locale as unique local variables are identified…

Decentralized System Control.

DTIC Science & Technology

1986-04-01

a Local Area Network Environment. Submitted for Publication. 1982. [Barrnger 791 Barringer . H,. P. C. Capon, and R . Phillips. The Portable Compiling...configuration and hardware. [Chesley 81 Chesley, Harry R . and Bruce V. Hunt., % Squire - A Communications-Oriented Operating System. Computer Networks 5(2...copying the information. Transfers between machines and copying " - r pages as necemry. [Nelson 80] Nelson, Bruce Jay. Remote Procedure Call. PhD Thesis

Impacts of Combined Cooling, Heating and Power Systems, and Rainwater Harvesting on Water Demand, Carbon Dioxide, and NOx Emissions for Atlanta.

PubMed

James, Jean-Ann; Sung, Sangwoo; Jeong, Hyunju; Broesicke, Osvaldo A; French, Steven P; Li, Duo; Crittenden, John C

2018-01-02

The purpose of this study is to explore the potential water, CO 2 and NO x emission, and cost savings that the deployment of decentralized water and energy technologies within two urban growth scenarios can achieve. We assess the effectiveness of urban growth, technological, and political strategies to reduce these burdens in the 13-county Atlanta metropolitan region. The urban growth between 2005 and 2030 was modeled for a business as usual (BAU) scenario and a more compact growth (MCG) scenario. We considered combined cooling, heating and power (CCHP) systems using microturbines for our decentralized energy technology and rooftop rainwater harvesting and low flow fixtures for the decentralized water technologies. Decentralized water and energy technologies had more of an impact in reducing the CO 2 and NO x emissions and water withdrawal and consumption than an MCG growth scenario (which does not consider energy for transit). Decentralized energy can reduce the CO 2 and NO x emissions by 8% and 63%, respectively. Decentralized energy and water technologies can reduce the water withdrawal and consumption in the MCG scenario by 49% and 50% respectively. Installing CCHP systems on both the existing and new building stocks with a net metering policy could reduce the CO 2 , NO x , and water consumption by 50%, 90%, and 75% respectively.

Decentralized control mechanism underlying interlimb coordination of millipedes.

PubMed

Kano, Takeshi; Sakai, Kazuhiko; Yasui, Kotaro; Owaki, Dai; Ishiguro, Akio

2017-04-04

Legged animals exhibit adaptive and resilient locomotion through interlimb coordination. The long-term goal of this study is to clarify the relationship between the number of legs and the inherent decentralized control mechanism for interlimb coordination. As a preliminary step, the study focuses on millipedes as they represent the species with the greatest number of legs among various animal species. A decentralized control mechanism involving local force feedback was proposed based on the qualitative findings of behavioural experiments in which responses to the removal of part of the terrain and leg amputation were observed. The proposed mechanism was implemented in a developed millipede-like robot to demonstrate that the robot can adapt to the removal of the part of the terrain and leg amputation in a manner similar to that in behavioural experiments.

77 FR 56625 - Privacy Act of 1974; Systems of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-13

... Internet at http://www.regulations.gov as they are received without change, including any personal.... George G. Meade, MD 20755-6000. Decentralized segments: Defense Intelligence Agency (DIA) Headquarters... decentralized system locations, write to the National Security Agency/Central Security Service, Freedom of...

Endogenous System Microbes as Treatment Process Indicators for Decentralized Non-potable Water Reuse

EPA Science Inventory

Monitoring the efficacy of treatment strategies to remove pathogens in decentralized systems remains a challenge. Evaluating log reduction targets by measuring pathogen levels is hampered by their sporadic and low occurrence rates. Fecal indicator bacteria are used in centraliz...

Academic Freedom.

ERIC Educational Resources Information Center

Ouchi, William G.

2004-01-01

Argues that school systems are so centralized that they waste money on bureaucratic operations and lack the capacity to respond rapidly to changing circumstances. A study of nine school systems that vary dramatically in their degree of decentralization demonstrates that true decentralization yields benefits in both efficiency and performance. (MLF)

A candidate architecture for monitoring and control in chemical transfer propulsion systems

NASA Technical Reports Server (NTRS)

Binder, Michael P.; Millis, Marc G.

1990-01-01

To support the exploration of space, a reusable space-based rocket engine must be developed. This engine must sustain superior operability and man-rated levels of reliability over several missions with limited maintenance or inspection between flights. To meet these requirements, an expander cycle engine incorporating a highly capable control and health monitoring system is planned. Alternatives for the functional organization and the implementation architecture of the engine's monitoring and control system are discussed. On the basis of this discussion, a decentralized architecture is favored. The trade-offs between several implementation options are outlined and future work is proposed.

[Analysis of the healthcare service decentralization process in Côte d'Ivoire].

PubMed

Soura, B D; Coulibaly, S S

2014-01-01

The decentralization of healthcare services is becoming increasingly important in strategies of public sector management. This concept is analyzed from various points of view, including legal, economic, political, and sociological. Several typologies have been proposed in the literature to analyze this decentralization process, which can take different forms ranging from simple deconcentration to more elaborate devolution. In some instances, decentralization can be analyzed by the degree of autonomy given to local authorities. This article applies these typologies to analyze the healthcare system decentralization process in Cote d'Ivoire. Special attention is paid to the new forms of community healthcare organizations. These decentralized structures enjoy a kind of autonomy, with characteristics closer to those of devolution. The model might serve as an example for population involvement in defining and managing healthcare problems in Cote d'Ivoire. We end with proposals for the improvement of the process.

Decentralized formation flying control in a multiple-team hierarchy.

PubMed

Mueller, Joseph B; Thomas, Stephanie J

2005-12-01

In recent years, formation flying has been recognized as an enabling technology for a variety of mission concepts in both the scientific and defense arenas. Examples of developing missions at NASA include magnetospheric multiscale (MMS), solar imaging radio array (SIRA), and terrestrial planet finder (TPF). For each of these missions, a multiple satellite approach is required in order to accomplish the large-scale geometries imposed by the science objectives. In addition, the paradigm shift of using a multiple satellite cluster rather than a large, monolithic spacecraft has also been motivated by the expected benefits of increased robustness, greater flexibility, and reduced cost. However, the operational costs of monitoring and commanding a fleet of close-orbiting satellites is likely to be unreasonable unless the onboard software is sufficiently autonomous, robust, and scalable to large clusters. This paper presents the prototype of a system that addresses these objectives-a decentralized guidance and control system that is distributed across spacecraft using a multiple team framework. The objective is to divide large clusters into teams of "manageable" size, so that the communication and computation demands driven by N decentralized units are related to the number of satellites in a team rather than the entire cluster. The system is designed to provide a high level of autonomy, to support clusters with large numbers of satellites, to enable the number of spacecraft in the cluster to change post-launch, and to provide for on-orbit software modification. The distributed guidance and control system will be implemented in an object-oriented style using a messaging architecture for networking and threaded applications (MANTA). In this architecture, tasks may be remotely added, removed, or replaced post launch to increase mission flexibility and robustness. This built-in adaptability will allow software modifications to be made on-orbit in a robust manner. The prototype system, which is implemented in Matlab, emulates the object-oriented and message-passing features of the MANTA software. In this paper, the multiple team organization of the cluster is described, and the modular software architecture is presented. The relative dynamics in eccentric reference orbits is reviewed, and families of periodic, relative trajectories are identified, expressed as sets of static geometric parameters. The guidance law design is presented, and an example reconfiguration scenario is used to illustrate the distributed process of assigning geometric goals to the cluster. Next, a decentralized maneuver planning approach is presented that utilizes linear-programming methods to enact reconfiguration and coarse formation keeping maneuvers. Finally, a method for performing online collision avoidance is discussed, and an example is provided to gauge its performance.

Development and application of a real-time testbed for multiagent system interoperability: A case study on hierarchical microgrid control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cintuglu, Mehmet Hazar; Youssef, Tarek; Mohammed, Osama A.

This article presents the development and application of a real-time testbed for multiagent system interoperability. As utility independent private microgrids are installed constantly, standardized interoperability frameworks are required to define behavioral models of the individual agents for expandability and plug-and-play operation. In this paper, we propose a comprehensive hybrid agent framework combining the foundation for intelligent physical agents (FIPA), IEC 61850, and data distribution service (DDS) standards. The IEC 61850 logical node concept is extended using FIPA based agent communication language (ACL) with application specific attributes and deliberative behavior modeling capability. The DDS middleware is adopted to enable a real-timemore » publisher-subscriber interoperability mechanism between platforms. The proposed multi-agent framework was validated in a laboratory based testbed involving developed intelligent electronic device (IED) prototypes and actual microgrid setups. Experimental results were demonstrated for both decentralized and distributed control approaches. Secondary and tertiary control levels of a microgrid were demonstrated for decentralized hierarchical control case study. A consensus-based economic dispatch case study was demonstrated as a distributed control example. Finally, it was shown that the developed agent platform is industrially applicable for actual smart grid field deployment.« less

Development and application of a real-time testbed for multiagent system interoperability: A case study on hierarchical microgrid control

DOE PAGES

Cintuglu, Mehmet Hazar; Youssef, Tarek; Mohammed, Osama A.

2016-08-10

This article presents the development and application of a real-time testbed for multiagent system interoperability. As utility independent private microgrids are installed constantly, standardized interoperability frameworks are required to define behavioral models of the individual agents for expandability and plug-and-play operation. In this paper, we propose a comprehensive hybrid agent framework combining the foundation for intelligent physical agents (FIPA), IEC 61850, and data distribution service (DDS) standards. The IEC 61850 logical node concept is extended using FIPA based agent communication language (ACL) with application specific attributes and deliberative behavior modeling capability. The DDS middleware is adopted to enable a real-timemore » publisher-subscriber interoperability mechanism between platforms. The proposed multi-agent framework was validated in a laboratory based testbed involving developed intelligent electronic device (IED) prototypes and actual microgrid setups. Experimental results were demonstrated for both decentralized and distributed control approaches. Secondary and tertiary control levels of a microgrid were demonstrated for decentralized hierarchical control case study. A consensus-based economic dispatch case study was demonstrated as a distributed control example. Finally, it was shown that the developed agent platform is industrially applicable for actual smart grid field deployment.« less

[Regional health systems management: a case study in Rio Grande do Sul, Brazil].

PubMed

Lima, Juliano de Carvalho; Rivera, Francisco Javier Uribe

2006-10-01

This article analyzes the management system in a health district in the State of Rio Grande do Sul, Brazil, through qualitative analysis, using a case study as the methodology and macro-organization theory as the analytical framework. For the current management system in the 6th Health Region, a clear mission statement and wide acceptance by health workers are facilitating factors for the current organizational practices within the health system. Nevertheless, the way health coordinators are currently prioritizing their time has diverted necessary resources from critical problems towards more remedial issues. The 6th Health Region has encouraged social control (or public oversight) in order to improve accountability. However, there is room for improvement in quality assurance management, since there were no well-defined goals, objectives, or accountability. Decentralized consultancy provided to the municipalities and the funding model itself have both promoted decentralization and autonomy, although the strategy requires better regional integration and greater commitment in managerial practices.

Robust decentralized power system controller design: Integrated approach

NASA Astrophysics Data System (ADS)

Veselý, Vojtech

2017-09-01

A unique approach to the design of gain scheduled controller (GSC) is presented. The proposed design procedure is based on the Bellman-Lyapunov equation, guaranteed cost and robust stability conditions using the parameter dependent quadratic stability approach. The obtained feasible design procedures for robust GSC design are in the form of BMI with guaranteed convex stability conditions. The obtained design results and their properties are illustrated in the simultaneously design of controllers for simple model (6-order) turbogenerator. The results of the obtained design procedure are a PI automatic voltage regulator (AVR) for synchronous generator, a PI governor controller and a power system stabilizer for excitation system.

Decentralized control of Markovian decision processes: Existence Sigma-admissable policies

NASA Technical Reports Server (NTRS)

Greenland, A.

1980-01-01

The problem of formulating and analyzing Markov decision models having decentralized information and decision patterns is examined. Included are basic examples as well as the mathematical preliminaries needed to understand Markov decision models and, further, to superimpose decentralized decision structures on them. The notion of a variance admissible policy for the model is introduced and it is proved that there exist (possibly nondeterministic) optional policies from the class of variance admissible policies. Directions for further research are explored.

DC Microgrids–Part I: A Review of Control Strategies and Stabilization Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dragicevic, Tomislav; Lu, Xiaonan; Vasquez, Juan

2015-01-01

This paper presents a review of control strategies, stability analysis, and stabilization techniques for dc microgrids (MGs). Overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level. As opposed to local control, which relies only on local measurements, some line of communication between units needs to be made available in order to achieve the coordinated control. Depending on the communication method, three basic coordinated control strategies can be distinguished, i.e., decentralized, centralized, and distributed control. Decentralized control can be regarded as an extension of the local control since it is also basedmore » exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches using these three coordinated control strategies to achieve various control objectives are reviewed in this paper. Moreover, properties of dc MG dynamics and stability are discussed. This paper illustrates that tightly regulated point-of-load converters tend to reduce the stability margins of the system since they introduce negative impedances, which can potentially oscillate with lightly damped power supply input filters. It is also demonstrated that how the stability of the whole system is defined by the relationship of the source and load impedances, referred to as the minor loop gain. Several prominent specifications for the minor loop gain are reviewed. Finally, a number of active stabilization techniques are presented.« less

Decentralized operating procedures for orchestrating data and behavior across distributed military systems and assets

NASA Astrophysics Data System (ADS)

Peach, Nicholas

2011-06-01

In this paper, we present a method for a highly decentralized yet structured and flexible approach to achieve systems interoperability by orchestrating data and behavior across distributed military systems and assets with security considerations addressed from the beginning. We describe an architecture of a tool-based design of business processes called Decentralized Operating Procedures (DOP) and the deployment of DOPs onto run time nodes, supporting the parallel execution of each DOP at multiple implementation nodes (fixed locations, vehicles, sensors and soldiers) throughout a battlefield to achieve flexible and reliable interoperability. The described method allows the architecture to; a) provide fine grain control of the collection and delivery of data between systems; b) allow the definition of a DOP at a strategic (or doctrine) level by defining required system behavior through process syntax at an abstract level, agnostic of implementation details; c) deploy a DOP into heterogeneous environments by the nomination of actual system interfaces and roles at a tactical level; d) rapidly deploy new DOPs in support of new tactics and systems; e) support multiple instances of a DOP in support of multiple missions; f) dynamically add or remove run-time nodes from a specific DOP instance as missions requirements change; g) model the passage of, and business reasons for the transmission of each data message to a specific DOP instance to support accreditation; h) run on low powered computers with lightweight tactical messaging. This approach is designed to extend the capabilities of existing standards, such as the Generic Vehicle Architecture (GVA).

Design Of Combined Stochastic Feedforward/Feedback Control

NASA Technical Reports Server (NTRS)

Halyo, Nesim

1989-01-01

Methodology accommodates variety of control structures and design techniques. In methodology for combined stochastic feedforward/feedback control, main objectives of feedforward and feedback control laws seen clearly. Inclusion of error-integral feedback, dynamic compensation, rate-command control structure, and like integral element of methodology. Another advantage of methodology flexibility to develop variety of techniques for design of feedback control with arbitrary structures to obtain feedback controller: includes stochastic output feedback, multiconfiguration control, decentralized control, or frequency and classical control methods. Control modes of system include capture and tracking of localizer and glideslope, crab, decrab, and flare. By use of recommended incremental implementation, control laws simulated on digital computer and connected with nonlinear digital simulation of aircraft and its systems.

Programs Related to Septic Systems

EPA Pesticide Factsheets

There are many programs, both at the EPA and elsewhere, that relate to the decentralized wastewater program and provide information about how decentralized wastewater is integrated in environmental quality, planning, protection, and conservation.

[Territory and decentralization in the agenda for productive transformation with equity].

PubMed

Sojo, A

1991-08-01

The regional perspective and the decentralization in Latin American and Caribbean countries was examined in light of technological changes and transformation of economic production to boost productivity. National population policies were not the major cause of redistribution of the population, rather such transformation significantly changed the comparative regional and urban advantages in the use of territory affecting the spatial distribution of the population. Hypotheses were advanced using the transformation of production, regional development, and decentralization on the retention, attraction, and migration of population in different areas with varying economic conditions. Spurious competitiveness means global strategies of enterprises that establish foreign operations by means of factor sourcing. Flexible specialization is a company strategy of permanent innovation based on flexible equipment and a qualified work force. The increasing transnationalization of capital is the source of skills and technology that sustain competitive advantages. Decentralization can resolve local demand, facilitate access to information, mobilize resources, and exercise control over local operations. In Japan, Germany, and Italy vs. the US and France there is a social contract among companies, trade unions, universities, and regional administrations in the interest of capital and the work force. There is no direct relationship between technology and region, the industrial cluster exhibits systemic competitiveness in developed countries (the Emilian model in Italy affirms the ability of small enterprises to develop new products), the regional impact is diverse relative to new technologies (some deprived rural economic areas have potential as in central and northern Italy), and population and region are linked (regional and rural-urban differences in the growth of population and migratory flows account for spatial distribution of the population). Decentralization and systemic competitiveness concern productivity and regional policies (spatial diversity for increased productivity) and technology and human resources are interdependent (technical progress is determined by the level of qualification of the population).

Endogenous System Microbes as Treatment Process ...

EPA Pesticide Factsheets

Monitoring the efficacy of treatment strategies to remove pathogens in decentralized systems remains a challenge. Evaluating log reduction targets by measuring pathogen levels is hampered by their sporadic and low occurrence rates. Fecal indicator bacteria are used in centralized systems to indicate the presence of fecal pathogens, but are ineffective decentralized treatment process indicators as they generally occur at levels too low to assess log reduction targets. System challenge testing by spiking with high loads of fecal indicator organisms, like MS2 coliphage, has limitations, especially for large systems. Microbes that are endogenous to the decentralized system, occur in high abundances and mimic removal rates of bacterial, viral and/or parasitic protozoan pathogens during treatment could serve as alternative treatment process indicators to verify log reduction targets. To identify abundant microbes in wastewater, the bacterial and viral communities were examined using deep sequencing. Building infrastructure-associated bacteria, like Zoogloea, were observed as dominant members of the bacterial community in graywater. In blackwater, bacteriophage of the order Caudovirales constituted the majority of contiguous sequences from the viral community. This study identifies candidate treatment process indicators in decentralized systems that could be used to verify log removal during treatment. The association of the presence of treatment process indic

Online Self-Organizing Social Systems: The Decentralized Future of Online Learning.

ERIC Educational Resources Information Center

Wiley, David A.; Edwards, Erin K.

2002-01-01

Describes an online self-organizing social system (OSOSS) which allows large numbers of individuals to self-organize in a highly decentralized manner to solve problems and accomplish other goals. Topics include scalability and bandwidth in online learning; self-organization; learning objects; instructional design underlying OSOSS, including…

Design and implementation of robust decentralized control laws for the ACES structure at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Collins, Emmanuel G., Jr.; Phillips, Douglas J.; Hyland, David C.

1990-01-01

Many large space system concepts will require active vibration control to satisfy critical performance requirements such as line-of-sight accuracy. In order for these concepts to become operational it is imperative that the benefits of active vibration control be practically demonstrated in ground based experiments. The results of the experiment successfully demonstrate active vibration control for a flexible structure. The testbed is the Active Control Technique Evaluation for Spacecraft (ACES) structure at NASA Marshall Space Flight Center. The ACES structure is dynamically traceable to future space systems and especially allows the study of line-of-sight control issues.

Safety and Convergence Analysis of Intersecting Aircraft Flows Under Decentralized Collision Avoidance

NASA Astrophysics Data System (ADS)

Dallal, Ahmed H.

Safety is an essential requirement for air traffic management and control systems. Aircraft are not allowed to get closer to each other than a specified safety distance, to avoid any conflicts and collisions between aircraft. Forecast analysis predicts a tremendous increase in the number of flights. Subsequently, automated tools are needed to help air traffic controllers resolve air born conflicts. In this dissertation, we consider the problem of conflict resolution of aircraft flows with the assumption that aircraft are flowing through a fixed specified control volume at a constant speed. In this regard, several centralized and decentralized resolution rules have been proposed for path planning and conflict avoidance. For the case of two intersecting flows, we introduce the concept of conflict touches, and a collaborative decentralized conflict resolution rule is then proposed and analyzed for two intersecting flows. The proposed rule is also able to resolved airborne conflicts that resulted from resolving another conflict via the domino effect. We study the safety conditions under the proposed conflict resolution and collision avoidance rule. Then, we use Lyapunov analysis to analytically prove the convergence of conflict resolution dynamics under the proposed rule. The analysis show that, under the proposed conflict resolution rule, the system of intersecting aircraft flows is guaranteed to converge to safe, conflict free, trajectories within a bounded time. Simulations are provided to verify the analytically derived conclusions and study the convergence of the conflict resolution dynamics at different encounter angles. Simulation results show that lateral deviations taken by aircraft in each flow, to resolve conflicts, are bounded, and aircraft converged to safe and conflict free trajectories, within a finite time.

Evaluating the Life Cycle Environmental Benefits and Trade-Offs of Water Reuse Systems for Net-Zero Buildings.

PubMed

Hasik, Vaclav; Anderson, Naomi E; Collinge, William O; Thiel, Cassandra L; Khanna, Vikas; Wirick, Jason; Piacentini, Richard; Landis, Amy E; Bilec, Melissa M

2017-02-07

Aging water infrastructure and increased water scarcity have resulted in higher interest in water reuse and decentralization. Rating systems for high-performance buildings implicitly promote the use of building-scale, decentralized water supply and treatment technologies. It is important to recognize the potential benefits and trade-offs of decentralized and centralized water systems in the context of high-performance buildings. For this reason and to fill a gap in the current literature, we completed a life cycle assessment (LCA) of the decentralized water system of a high-performance, net-zero energy, net-zero water building (NZB) that received multiple green building certifications and compared the results with two modeled buildings (conventional and water efficient) using centralized water systems. We investigated the NZB's impacts over varying lifetimes, conducted a break-even analysis, and included Monte Carlo uncertainty analysis. The results show that, although the NZB performs better in most categories than the conventional building, the water efficient building generally outperforms the NZB. The lifetime of the NZB, septic tank aeration, and use of solar energy have been found to be important factors in the NZB's impacts. While these findings are specific to the case study building, location, and treatment technologies, the framework for comparison of water and wastewater impacts of various buildings can be applied during building design to aid decision making. As we design and operate high-performance buildings, the potential trade-offs of advanced decentralized water treatment systems should be considered.

A distributed database view of network tracking systems

NASA Astrophysics Data System (ADS)

Yosinski, Jason; Paffenroth, Randy

2008-04-01

In distributed tracking systems, multiple non-collocated trackers cooperate to fuse local sensor data into a global track picture. Generating this global track picture at a central location is fairly straightforward, but the single point of failure and excessive bandwidth requirements introduced by centralized processing motivate the development of decentralized methods. In many decentralized tracking systems, trackers communicate with their peers via a lossy, bandwidth-limited network in which dropped, delayed, and out of order packets are typical. Oftentimes the decentralized tracking problem is viewed as a local tracking problem with a networking twist; we believe this view can underestimate the network complexities to be overcome. Indeed, a subsequent 'oversight' layer is often introduced to detect and handle track inconsistencies arising from a lack of robustness to network conditions. We instead pose the decentralized tracking problem as a distributed database problem, enabling us to draw inspiration from the vast extant literature on distributed databases. Using the two-phase commit algorithm, a well known technique for resolving transactions across a lossy network, we describe several ways in which one may build a distributed multiple hypothesis tracking system from the ground up to be robust to typical network intricacies. We pay particular attention to the dissimilar challenges presented by network track initiation vs. maintenance and suggest a hybrid system that balances speed and robustness by utilizing two-phase commit for only track initiation transactions. Finally, we present simulation results contrasting the performance of such a system with that of more traditional decentralized tracking implementations.

Organizational decentralization in radiology.

PubMed

Aas, I H Monrad

2006-01-01

At present, most hospitals have a department of radiology where images are captured and interpreted. Decentralization is the opposite of centralization and means 'away from the centre'. With a Picture Archiving and Communication System (PACS) and broadband communications, transmitting radiology images between sites will be far easier than before. Qualitative interviews of 26 resource persons were performed in Norway. There was a response rate of 90%. Decentralization of radiology interpretations seems less relevant than centralization, but several forms of decentralization have a role to play. The respondents mentioned several advantages, including exploitation of capacity and competence. They also mentioned several disadvantages, including splitting professional communities and reduced contact between radiologists and clinicians. With the new technology decentralization and centralization of image interpretation are important possibilities in organizational change. This will be important for the future of teleradiology.

Effects of health care decentralization in Spain from a citizens' perspective.

PubMed

Antón, José-Ignacio; Muñoz de Bustillo, Rafael; Fernández Macías, Enrique; Rivera, Jesús

2014-05-01

The aim of this article is to analyze the impact of the decentralization of the public national health system in Spain on citizens' satisfaction with different dimensions of primary and hospital care. Using micro-data from the Health Barometer 1996-2009 and taking advantage of the exogeneity of the different pace of decentralization across Spain using a difference-in-differences strategy, we find that, in general, decentralization has not improved citizens' satisfaction with different features of the health services. In our base model, we find that there are even some small negative effects on a subset of variables. Sensitivity analysis confirms that there is no empirical evidence for supporting that decentralization has had a positive impact on citizens' satisfaction with health care. We outline several possible reasons for this.

Decentralized Fuzzy MPC on Spatial Power Control of a Large PHWR

NASA Astrophysics Data System (ADS)

Liu, Xiangjie; Jiang, Di; Lee, Kwang Y.

2016-08-01

Reliable power control for stabilizing the spatial oscillations is quite important for ensuring the safe operation of a modern pressurized heavy water reactor (PHWR), since these spatial oscillations can cause “flux tilting” in the reactor core. In this paper, a decentralized fuzzy model predictive control (DFMPC) is proposed for spatial control of PHWR. Due to the load dependent dynamics of the nuclear power plant, fuzzy modeling is used to approximate the nonlinear process. A fuzzy Lyapunov function and “quasi-min-max” strategy is utilized in designing the DFMPC, to reduce the conservatism. The plant-wide stability is achieved by the asymptotically positive realness constraint (APRC) for this decentralized MPC. The solving optimization problem is based on a receding horizon scheme involving the linear matrix inequalities (LMIs) technique. Through dynamic simulations, it is demonstrated that the designed DFMPC can effectively suppress spatial oscillations developed in PHWR, and further, shows the advantages over the typical parallel distributed compensation (PDC) control scheme.

Improving antiretroviral therapy scale-up and effectiveness through service integration and decentralization.

PubMed

Suthar, Amitabh B; Rutherford, George W; Horvath, Tara; Doherty, Meg C; Negussie, Eyerusalem K

2014-03-01

Current service delivery systems do not reach all people in need of antiretroviral therapy (ART). In order to inform the operational and service delivery section of the WHO 2013 consolidated antiretroviral guidelines, our objective was to summarize systematic reviews on integrating ART delivery into maternal, newborn, and child health (MNCH) care settings in countries with generalized epidemics, tuberculosis (TB) treatment settings in which the burden of HIV and TB is high, and settings providing opiate substitution therapy (OST); and decentralizing ART into primary health facilities and communities. A summary of systematic reviews. The reviewers searched PubMed, Embase, PsycINFO, Web of Science, CENTRAL, and the WHO Index Medicus databases. Randomized controlled trials and observational cohort studies were included if they compared ART coverage, retention in HIV care, and/or mortality in MNCH, TB, or OST facilities providing ART with MNCH, TB, or OST facilities providing ART services separately; or primary health facilities or communities providing ART with hospitals providing ART. The reviewers identified 28 studies on integration and decentralization. Antiretroviral therapy integration into MNCH facilities improved ART coverage (relative risk [RR] 1.37, 95% confidence interval [CI] 1.05-1.79) and led to comparable retention in care. ART integration into TB treatment settings improved ART coverage (RR 1.83, 95% CI 1.48-2.23) and led to a nonsignificant reduction in mortality (RR 0.55, 95% CI 0.29-1.05). The limited data on ART integration into OST services indicated comparable rates of ART coverage, retention, and mortality. Partial decentralization into primary health facilities improved retention (RR 1.05, 95% CI 1.01-1.09) and reduced mortality (RR 0.34, 95% CI 0.13-0.87). Full decentralization improved retention (RR 1.12, 95% CI 1.08-1.17) and led to comparable mortality. Community-based ART led to comparable rates of retention and mortality. Integrating ART into MNCH, TB, and OST services was often associated with improvements in ART coverage, and decentralization of ART into primary health facilities and communities was often associated with improved retention. Neither integration nor decentralization was associated with adverse outcomes. These data contributed to recommendations in the WHO 2013 consolidated antiretroviral guidelines to integrate ART delivery into MNCH, TB, and OST services and to decentralize ART.

Decentralized model reference adaptive control of large flexible structures

NASA Technical Reports Server (NTRS)

Lee, Fu-Ming; Fong, I-Kong; Lin, Yu-Hwan

1988-01-01

A decentralized model reference adaptive control (DMRAC) method is developed for large flexible structures (LFS). The development follows that of a centralized model reference adaptive control for LFS that have been shown to be feasible. The proposed method is illustrated using a simply supported beam with collocated actuators and sensors. Results show that the DMRAC can achieve either output regulation or output tracking with adequate convergence, provided the reference model inputs and their time derivatives are integrable, bounded, and approach zero as t approaches infinity.

The Large Introductory Class as an Exercise in Organization Design.

ERIC Educational Resources Information Center

Wagner, John A., III; Van Dyne, Linn

1999-01-01

Four methods for large group instruction differ in control and coordination dimensions: (1) centralization with mutual adjustment; (2) centralization with standardization; (3) decentralization with standardization; and (4) decentralization with mutual adjustment. Other factors to consider include class size and interests of various constituencies:…

Problems in Decentralized Decision making and Computation.

DTIC Science & Technology

1984-12-01

systesis being referred to. Findeisen [1982] clarifies this distinction by talking about the "programing" and "execution" phases.) 5. The lower and higher...n ... *iii... -258- Findeisen , W., (1982), "Decentralized and Hierarchical Control Under Consistency or Disagreement of Interest," Automatica, Vol. 18

Distributed Coordinated Control of Large-Scale Nonlinear Networks

DOE PAGES

Kundu, Soumya; Anghel, Marian

2015-11-08

We provide a distributed coordinated approach to the stability analysis and control design of largescale nonlinear dynamical systems by using a vector Lyapunov functions approach. In this formulation the large-scale system is decomposed into a network of interacting subsystems and the stability of the system is analyzed through a comparison system. However finding such comparison system is not trivial. In this work, we propose a sum-of-squares based completely decentralized approach for computing the comparison systems for networks of nonlinear systems. Moreover, based on the comparison systems, we introduce a distributed optimal control strategy in which the individual subsystems (agents) coordinatemore » with their immediate neighbors to design local control policies that can exponentially stabilize the full system under initial disturbances.We illustrate the control algorithm on a network of interacting Van der Pol systems.« less

A novel test method to determine the filter material service life of decentralized systems treating runoff from traffic areas.

PubMed

Huber, Maximilian; Welker, Antje; Dierschke, Martina; Drewes, Jörg E; Helmreich, Brigitte

2016-09-01

In recent years, there has been a significant increase in the development and application of technical decentralized filter systems for the treatment of runoff from traffic areas. However, there are still many uncertainties regarding the service life and the performance of filter materials that are employed in decentralized treatment systems. These filter media are designed to prevent the transport of pollutants into the environment. A novel pilot-scale test method was developed to determine - within a few days - the service lives and long-term removal efficiencies for dissolved heavy metals in stormwater treatment systems. The proposed method consists of several steps including preloading the filter media in a pilot-scale model with copper and zinc by a load of n-1 years of the estimated service life (n). Subsequently, three representative rain events are simulated to evaluate the long-term performance by dissolved copper and zinc during the last year of application. The presented results, which verified the applicability of this method, were obtained for three filter channel systems and six filter shaft systems. The performance of the evaluated systems varied largely for both tested heavy metals and during all three simulated rain events. A validation of the pilot-scale assessment method with field measurements was also performed for two systems. Findings of this study suggest that this novel method does provide a standardized and accurate estimation of service intervals of decentralized treatment systems employing various filter materials. The method also provides regulatory authorities, designers, and operators with an objective basis for performance assessment and supports stormwater managers to make decisions for the installation of such decentralized treatment systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigating the interactions of decentralized and centralized wastewater heat recovery systems.

PubMed

Sitzenfrei, Robert; Hillebrand, Sebastian; Rauch, Wolfgang

2017-03-01

In the urban water cycle there are different sources for extracting energy. In addition to potential and chemical energy in the wastewater, thermal energy can also be recovered. Heat can be recovered from the wastewater with heat exchangers that are located decentralized and/or centralized at several locations throughout the system. It can be recovered directly at the source (e.g. in the showers and bathrooms), at building block level (e.g. warm water tanks collecting all grey water), in sewers or at the wastewater treatment plant. However, an uncoordinated installation of systems on such different levels can lead to competing technologies. To investigate these interactions, a modelling environment is set up, tested and calibrated based on continuous sewer temperature and flow measurements. With that approach different heat recovery scenarios on a household level (decentralized) and of in-sewer heat recovery (centralized) are investigated. A maximum performance drop of 40% for a centralized energy recovery system was estimated when all bathrooms are equipped with decentralized recovery systems. Therefore, the proposed modelling approach is suitable for testing different future conditions and to identify robust strategies for heat recovery systems from wastewater.

Annual Review of Research under the Joint Services Electronics Program,

DTIC Science & Technology

1981-12-01

nonlinear system under investigation to be transformed, without approximation, into an equivalent linear system to which classical design methodologies are...employed his work in the design of an experimental helicopter autopilot which is presently under- going simulation and is expected to fly in the near...decentralized, and non -quad- duced from that which would be required ratic systems is presented. Here, one for an optimal non -linlar controller. designs a

Decentralized Optimal Dispatch of Photovoltaic Inverters in Residential Distribution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Dhople, Sairaj V.; Johnson, Brian B.

Summary form only given. Decentralized methods for computing optimal real and reactive power setpoints for residential photovoltaic (PV) inverters are developed in this paper. It is known that conventional PV inverter controllers, which are designed to extract maximum power at unity power factor, cannot address secondary performance objectives such as voltage regulation and network loss minimization. Optimal power flow techniques can be utilized to select which inverters will provide ancillary services, and to compute their optimal real and reactive power setpoints according to well-defined performance criteria and economic objectives. Leveraging advances in sparsity-promoting regularization techniques and semidefinite relaxation, this papermore » shows how such problems can be solved with reduced computational burden and optimality guarantees. To enable large-scale implementation, a novel algorithmic framework is introduced - based on the so-called alternating direction method of multipliers - by which optimal power flow-type problems in this setting can be systematically decomposed into sub-problems that can be solved in a decentralized fashion by the utility and customer-owned PV systems with limited exchanges of information. Since the computational burden is shared among multiple devices and the requirement of all-to-all communication can be circumvented, the proposed optimization approach scales favorably to large distribution networks.« less

Modeling, Analysis, and Control of a Hypersonic Vehicle with Significant Aero-Thermo-Elastic-Propulsion Interactions: Elastic, Thermal and Mass Uncertainty

NASA Astrophysics Data System (ADS)

Khatri, Jaidev

This thesis examines themodeling, analysis, and control system design issues for scramjet powered hypersonic vehicles. A nonlinear three degrees of freedom longitudinal model which includes aero-propulsion-elasticity effects was used for all analyses. This model is based upon classical compressible flow and Euler-Bernouli structural concepts. Higher fidelity computational fluid dynamics and finite element methods are needed for more precise intermediate and final evaluations. The methods presented within this thesis were shown to be useful for guiding initial control relevant design. The model was used to examine the vehicle's static and dynamic characteristics over the vehicle's trimmable region. The vehicle has significant longitudinal coupling between the fuel equivalency ratio (FER) and the flight path angle (FPA). For control system design, a two-input two-output plant (FER - elevator to speed-FPA) with 11 states (including 3 flexible modes) was used. Velocity, FPA, and pitch were assumed to be available for feedback. Aerodynamic heat modeling and design for the assumed TPS was incorporated to original Bolender's model to study the change in static and dynamic properties. De-centralized control stability, feasibility and limitations issues were dealt with the change in TPS elasticity, mass and physical dimension. The impact of elasticity due to TPS mass, TPS physical dimension as well as prolonged heating was also analyzed to understand performance limitations of de-centralized control designed for nominal model.

New Decentralized Algorithms for Spacecraft Formation Control Based on a Cyclic Approach

DTIC Science & Technology

2010-06-01

space framework. As metric of performance, a common quadratic norm that weights the performance error and the control effort is traded with the cost...R = DTD, then the metric of interest is (’J)",,, the square of the 2-norm from input w to output z. Given a system G with state space description A ... spaced logarithmic spiral formation. These results are derived for

Chained Aggregation and Control System Design:; A Geometric Approach.

DTIC Science & Technology

1982-10-01

Furthermore, it explicitly identifies a reduced order modal used to meet the design goals. This results in an interactive design pro- cedure which allows...same framework. This leads directly to dynamic compen- sator design. The results are applied to decentralized control problems, non interactive ...goals. Furthermore, it explicitly identifies a reduced order model used to meet the design goals. This results in an interactive design procedure which

On decentralized estimation. [for large linear systems

NASA Technical Reports Server (NTRS)

Siljak, D. D.; Vukcevic, M. B.

1978-01-01

A multilevel scheme is proposed to construct decentralized estimators for large linear systems. The scheme is numerically attractive since only observability tests of low-order subsystems are required. Equally important is the fact that the constructed estimators are reliable under structural perturbations and can tolerate a wide range of nonlinearities in coupling among the subsystems.

Decentralization and equity of resource allocation: evidence from Colombia and Chile.

PubMed Central

Bossert, Thomas J.; Larrañaga, Osvaldo; Giedion, Ursula; Arbelaez, José Jesus; Bowser, Diana M.

2003-01-01

OBJECTIVE: To investigate the relation between decentralization and equity of resource allocation in Colombia and Chile. METHODS: The "decision space" approach and analysis of expenditures and utilization rates were used to provide a comparative analysis of decentralization of the health systems of Colombia and Chile. FINDINGS: Evidence from Colombia and Chile suggests that decentralization, under certain conditions and with some specific policy mechanisms, can improve equity of resource allocation. In these countries, equitable levels of per capita financial allocations at the municipal level were achieved through different forms of decentralization--the use of allocation formulae, adequate local funding choices and horizontal equity funds. Findings on equity of utilization of services were less consistent, but they did show that increased levels of funding were associated with increased utilization. This suggests that improved equity of funding over time might reduce inequities of service utilization. CONCLUSION: Decentralization can contribute to, or at least maintain, equitable allocation of health resources among municipalities of different incomes. PMID:12751417

Construction of a controllable β-carotene biosynthetic pathway by decentralized assembly strategy in Saccharomyces cerevisiae.

PubMed

Xie, Wenping; Liu, Min; Lv, Xiaomei; Lu, Wenqiang; Gu, Jiali; Yu, Hongwei

2014-01-01

Saccharomyces cerevisiae is an important platform organism for the synthesis of a great number of natural products. However, the assembly of controllable and genetically stable heterogeneous biosynthetic pathways in S. cerevisiae still remains a significant challenge. Here, we present a strategy for reconstructing controllable multi-gene pathways by employing the GAL regulatory system. A set of marker recyclable integrative plasmids (pMRI) was designed for decentralized assembly of pathways. As proof-of-principle, a controllable β-carotene biosynthesis pathway (∼16 kb) was reconstructed and optimized by repeatedly using GAL10-GAL1 bidirectional promoters with high efficiency (80-100%). By controling the switch time of the pathway, production of 11 mg/g DCW of total carotenoids (72.57 mg/L) and 7.41 mg/g DCW of β-carotene was achieved in shake-flask culture. In addition, the engineered yeast strain exhibited high genetic stability after 20 generations of subculture. The results demonstrated a controllable and genetically stable biosynthetic pathway capable of increasing the yield of target products. Furthermore, the strategy presented in this study could be extended to construct other pathways in S. cerevisisae. © 2013 Wiley Periodicals, Inc.

Distributed Engine Control Empirical/Analytical Verification Tools

NASA Technical Reports Server (NTRS)

DeCastro, Jonathan; Hettler, Eric; Yedavalli, Rama; Mitra, Sayan

2013-01-01

NASA's vision for an intelligent engine will be realized with the development of a truly distributed control system featuring highly reliable, modular, and dependable components capable of both surviving the harsh engine operating environment and decentralized functionality. A set of control system verification tools was developed and applied to a C-MAPSS40K engine model, and metrics were established to assess the stability and performance of these control systems on the same platform. A software tool was developed that allows designers to assemble easily a distributed control system in software and immediately assess the overall impacts of the system on the target (simulated) platform, allowing control system designers to converge rapidly on acceptable architectures with consideration to all required hardware elements. The software developed in this program will be installed on a distributed hardware-in-the-loop (DHIL) simulation tool to assist NASA and the Distributed Engine Control Working Group (DECWG) in integrating DCS (distributed engine control systems) components onto existing and next-generation engines.The distributed engine control simulator blockset for MATLAB/Simulink and hardware simulator provides the capability to simulate virtual subcomponents, as well as swap actual subcomponents for hardware-in-the-loop (HIL) analysis. Subcomponents can be the communication network, smart sensor or actuator nodes, or a centralized control system. The distributed engine control blockset for MATLAB/Simulink is a software development tool. The software includes an engine simulation, a communication network simulation, control algorithms, and analysis algorithms set up in a modular environment for rapid simulation of different network architectures; the hardware consists of an embedded device running parts of the CMAPSS engine simulator and controlled through Simulink. The distributed engine control simulation, evaluation, and analysis technology provides unique capabilities to study the effects of a given change to the control system in the context of the distributed paradigm. The simulation tool can support treatment of all components within the control system, both virtual and real; these include communication data network, smart sensor and actuator nodes, centralized control system (FADEC full authority digital engine control), and the aircraft engine itself. The DECsim tool can allow simulation-based prototyping of control laws, control architectures, and decentralization strategies before hardware is integrated into the system. With the configuration specified, the simulator allows a variety of key factors to be systematically assessed. Such factors include control system performance, reliability, weight, and bandwidth utilization.

Decentralized Online Social Networks

NASA Astrophysics Data System (ADS)

Datta, Anwitaman; Buchegger, Sonja; Vu, Le-Hung; Strufe, Thorsten; Rzadca, Krzysztof

Current Online social networks (OSN) are web services run on logically centralized infrastructure. Large OSN sites use content distribution networks and thus distribute some of the load by caching for performance reasons, nevertheless there is a central repository for user and application data. This centralized nature of OSNs has several drawbacks including scalability, privacy, dependence on a provider, need for being online for every transaction, and a lack of locality. There have thus been several efforts toward decentralizing OSNs while retaining the functionalities offered by centralized OSNs. A decentralized online social network (DOSN) is a distributed system for social networking with no or limited dependency on any dedicated central infrastructure. In this chapter we explore the various motivations of a decentralized approach to online social networking, discuss several concrete proposals and types of DOSN as well as challenges and opportunities associated with decentralization.

TROTER's (Tiny Robotic Operation Team Experiment): A new concept of space robots

NASA Technical Reports Server (NTRS)

Su, Renjeng

1990-01-01

In view of the future need of automation and robotics in space and the existing approaches to the problem, we proposed a new concept of robots for space construction. The new concept is based on the basic idea of decentralization. Decentralization occurs, on the one hand, in using teams of many cooperative robots for construction tasks. Redundancy and modular design are explored to achieve high reliability for team robotic operations. Reliability requirement on individual robots is greatly reduced. Another area of decentralization is manifested by the proposed control hierarchy which eventually includes humans in the loop. The control strategy is constrained by various time delays and calls for different levels of abstraction of the task dynamics. Such technology is needed for remote control of robots in an uncertain environment. Thus, concerns of human safety around robots are relaxed. This presentation also introduces the required technologies behind the new robotic concept.

[Mes differ by positioning: empirical testing of decentralized dynamics of the self].

PubMed

Mizokami, Shinichi

2013-10-01

The present study empirically tested the conceptualization of the decentralized dynamics of the self proposed by Hermans & Kempen (1993), which they developed theoretically and from clinical cases, not from large samples of empirical data. They posited that worldviews and images of the self could vary by positioning even in the same individual, and denied that the ego was an omniscient entity that knew and controlled all aspects of the self (centralized ego). Study 1 tested their conceptualization empirically with 47 university students in an experimental group and 17 as a control group. The results showed that the scores on the Rosenberg's self-esteem scale and images of the Mes in the experimental group significantly varied by positioning, but those in the control group did not. Similar results were found in Study 2 with a sample of 120 university students. These results empirically supported the conceptualization of the decentralized dynamics of the self.

A three-level atomicity model for decentralized workflow management systems

NASA Astrophysics Data System (ADS)

Ben-Shaul, Israel Z.; Heineman, George T.

1996-12-01

A workflow management system (WFMS) employs a workflow manager (WM) to execute and automate the various activities within a workflow. To protect the consistency of data, the WM encapsulates each activity with a transaction; a transaction manager (TM) then guarantees the atomicity of activities. Since workflows often group several activities together, the TM is responsible for guaranteeing the atomicity of these units. There are scalability issues, however, with centralized WFMSs. Decentralized WFMSs provide an architecture for multiple autonomous WFMSs to interoperate, thus accommodating multiple workflows and geographically-dispersed teams. When atomic units are composed of activities spread across multiple WFMSs, however, there is a conflict between global atomicity and local autonomy of each WFMS. This paper describes a decentralized atomicity model that enables workflow administrators to specify the scope of multi-site atomicity based upon the desired semantics of multi-site tasks in the decentralized WFMS. We describe an architecture that realizes our model and execution paradigm.

Development of an interface for an ultrareliable fault-tolerant control system and an electronic servo-control unit

NASA Technical Reports Server (NTRS)

Shaver, Charles; Williamson, Michael

1986-01-01

The NASA Ames Research Center sponsors a research program for the investigation of Intelligent Flight Control Actuation systems. The use of artificial intelligence techniques in conjunction with algorithmic techniques for autonomous, decentralized fault management of flight-control actuation systems is explored under this program. The design, development, and operation of the interface for laboratory investigation of this program is documented. The interface, architecturally based on the Intel 8751 microcontroller, is an interrupt-driven system designed to receive a digital message from an ultrareliable fault-tolerant control system (UFTCS). The interface links the UFTCS to an electronic servo-control unit, which controls a set of hydraulic actuators. It was necessary to build a UFTCS emulator (also based on the Intel 8751) to provide signal sources for testing the equipment.

Adaptive Probabilistic Protocols for Advanced Networks/Assuring the Integrity of Highly Decentralized Communications Systems

DTIC Science & Technology

2005-03-01

to obtain a protocol customized to the needs of a specific setting, under control of an automated theorem proving system that can guarantee...new “compositional” method for protocol design and implementation, in which small microprotocols are combined to obtain a protocol customized to the...and Network Centric Enterprise (NCES) visions. This final report documents a wide range of contributions and technology transitions, including: A

A decentralized process for finding equilibria given by linear equations.

PubMed Central

Reiter, S

1994-01-01

I present a decentralized process for finding the equilibria of an economy characterized by a finite number of linear equilibrium conditions. The process finds all equilibria or, if there are none, reports that, in a finite number of steps at most equal to the number of equations. The communication and computational complexity compare favorably with other decentralized processes. The process may also be interpreted as an algorithm for solving a distributed system of linear equations. Comparisons with the Linpack program for LU (lower and upper triangular decomposition of the matrix of the equation system, a version of Gaussian elimination) are presented. PMID:11607486

Analyzing the effects of transit network change on agency performance and riders in a decentralized, small-to-mid-sized US metropolitan area : a case study of Tallahassee, Florida.

DOT National Transportation Integrated Search

2013-05-01

On July 11, 2011, StarMetro, the local public transit agency in Tallahassee, Florida, restructured its entire bus network from a : downtown-focused radial system to a decentralized, grid-like system that local officials and agency leaders believed wo...

Holistic Evaluation of Decentralized Water Reuse: Life Cycle Assessment and Cost Analysis of Membrane Bioreactor Systems in Water Reuse Implementation

EPA Science Inventory

Understand environmental and cost impacts of transitional decentralized MBR systems with sewer mining Assess aerobic MBRs (AeMBR) and anaerobic MBRs (AnMBR) Use LCA and life cycle cost (LCC) analysis to quantify impacts Investigate LCA and LCC performance of MBRs under various re...

DServO: A Peer-to-Peer-based Approach to Biomedical Ontology Repositories.

PubMed

Mambone, Zakaria; Savadogo, Mahamadi; Some, Borlli Michel Jonas; Diallo, Gayo

2015-01-01

We present in this poster an extension of the ServO ontology server system, which adopts a decentralized Peer-To-Peer approach for managing multiple heterogeneous knowledge organization systems. It relies on the use of the JXTA protocol coupled with information retrieval techniques to provide a decentralized infrastructure for managing multiples instances of Ontology Repositories.

Educational Reform in Colombia and Venezuela: An Organizational Analysis: Occasional Papers in Education and Development Number 4.

ERIC Educational Resources Information Center

Hanson, Mark

This paper examines (1) attempts at educational reform in Venezuela and Colombia by means of decentralization, and (2) the impact of decentralization on two contrasting educational systems. In Venezuela, the national school system was highly centralized with even routine decisions being made in Caracas, which resulted in a rigid, unresponsive…

Fixed Point Learning Based Intelligent Traffic Control System

NASA Astrophysics Data System (ADS)

Zongyao, Wang; Cong, Sui; Cheng, Shao

2017-10-01

Fixed point learning has become an important tool to analyse large scale distributed system such as urban traffic network. This paper presents a fixed point learning based intelligence traffic network control system. The system applies convergence property of fixed point theorem to optimize the traffic flow density. The intelligence traffic control system achieves maximum road resources usage by averaging traffic flow density among the traffic network. The intelligence traffic network control system is built based on decentralized structure and intelligence cooperation. No central control is needed to manage the system. The proposed system is simple, effective and feasible for practical use. The performance of the system is tested via theoretical proof and simulations. The results demonstrate that the system can effectively solve the traffic congestion problem and increase the vehicles average speed. It also proves that the system is flexible, reliable and feasible for practical use.

The Role of the Independent Sector in a Modern Democratic Society. An European View.

ERIC Educational Resources Information Center

Mason, Peter

This document discusses the shift in democratic countries toward the allocation of responsibility for the organization and control of education in the public system by decentralization from the center to the local community and beyond, to the governing bodies of individual schools, and to the parents who are represented on school councils. This…

A Decentralized Adaptive Approach to Fault Tolerant Flight Control

NASA Technical Reports Server (NTRS)

Wu, N. Eva; Nikulin, Vladimir; Heimes, Felix; Shormin, Victor

2000-01-01

This paper briefly reports some results of our study on the application of a decentralized adaptive control approach to a 6 DOF nonlinear aircraft model. The simulation results showed the potential of using this approach to achieve fault tolerant control. Based on this observation and some analysis, the paper proposes a multiple channel adaptive control scheme that makes use of the functionally redundant actuating and sensing capabilities in the model, and explains how to implement the scheme to tolerate actuator and sensor failures. The conditions, under which the scheme is applicable, are stated in the paper.

Historical and Cultural Perspectives on Centralization/Decentralization in Continuing Education.

ERIC Educational Resources Information Center

Edelson, Paul J.

1995-01-01

Views centralization/decentralization from four perspectives: historical, as an outgrowth of professionalism, in the culture of higher education, and management theory. Suggests that some form of centralized control will always be necessary if continuing education is to function in a larger organization, but smaller units may be the wave of the…

Parental Contributions, School-Level Finances and Decentralization: An Analysis of Nicaraguan Autonomous School Budgets

ERIC Educational Resources Information Center

Gershberg, Alec Ian; Meade, Ben

2005-01-01

The Nicaraguan Autonomous School Programme is notable among the growing number of school governance decentralization reforms in the Americas in the degree of control given to parents, especially in decisions regarding the allocation of school resources. Much of schools' discretionary spending was accumulated through various school charges. This…

ALEPH: Israel's Research Library Network: Background, Evolution, and Implications for Networking in a Small Country.

ERIC Educational Resources Information Center

Lazinger, Susan S.

1991-01-01

Describes ALEPH, the research library network in Israel, and analyzes the strengths and weaknesses of its decentralized structure. Highlights include comparisons between RLIN and ALEPH; centralized versus decentralized networks; the format of ALEPH; authority control in ALEPH; and non-Roman scripts in both networks. (16 references) (LRW)

Using a Novel Wireless-Networked Decentralized Control Scheme under Unpredictable Environmental Conditions

PubMed Central

Chang, Chung-Liang; Huang, Yi-Ming; Hong, Guo-Fong

2015-01-01

The direction of sunshine or the installation sites of environmental control facilities in the greenhouse result in different temperature and humidity levels in the various zones of the greenhouse, and thus, the production quality of crop is inconsistent. This study proposed a wireless-networked decentralized fuzzy control scheme to regulate the environmental parameters of various culture zones within a greenhouse. The proposed scheme can create different environmental conditions for cultivating different crops in various zones and achieve diversification or standardization of crop production. A star-type wireless sensor network is utilized to communicate with each sensing node, actuator node, and control node in various zones within the greenhouse. The fuzzy rule-based inference system is used to regulate the environmental parameters for temperature and humidity based on real-time data of plant growth response provided by a growth stage selector. The growth stage selector defines the control ranges of temperature and humidity of the various culture zones according to the leaf area of the plant, the number of leaves, and the cumulative amount of light. The experimental results show that the proposed scheme is stable and robust and provides basis for future greenhouse applications. PMID:26569264

Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments

NASA Astrophysics Data System (ADS)

Poplawski, Blazej; Mikułowski, Grzegorz; Mróz, Arkadiusz; Jankowski, Łukasz

2018-02-01

This paper proposes, tests numerically and verifies experimentally a decentralized control algorithm with local feedback for semi-active mitigation of free vibrations in frame structures. The algorithm aims at transferring the vibration energy of low-order, lightly-damped structural modes into high-frequency modes of vibration, where it is quickly damped by natural mechanisms of material damping. Such an approach to mitigation of vibrations, known as the prestress-accumulation release (PAR) strategy, has been earlier applied only in global control schemes to the fundamental vibration mode of a cantilever beam. In contrast, the decentralization and local feedback allows the approach proposed here to be applied to more complex frame structures and vibration patterns, where the global control ceases to be intuitively obvious. The actuators (truss-frame nodes with controllable ability to transmit moments) are essentially unblockable hinges that become unblocked only for very short time periods in order to trigger local modal transfer of energy. The paper proposes a computationally simple model of the controllable nodes, specifies the control performance measure, yields basic characteristics of the optimum control, proposes the control algorithm and then tests it in numerical and experimental examples.

Integrated flight/propulsion control system design based on a decentralized, hierarchical approach

NASA Technical Reports Server (NTRS)

Mattern, Duane; Garg, Sanjay; Bullard, Randy

1989-01-01

A sample integrated flight/propulsion control system design is presented for the piloted longitudinal landing task with a modern, statistically unstable fighter aircraft. The design procedure is summarized. The vehicle model used in the sample study is described, and the procedure for partitioning the integrated system is presented along with a description of the subsystems. The high-level airframe performance specifications and control design are presented and the control performance is evaluated. The generation of the low-level (engine) subsystem specifications from the airframe requirements are discussed, and the engine performance specifications are presented along with the subsystem control design. A compensator to accommodate the influence of airframe outputs on the engine subsystem is also considered. Finally, the entire closed loop system performance and stability characteristics are examined.

Integrated flight/propulsion control system design based on a decentralized, hierarchical approach

NASA Technical Reports Server (NTRS)

Mattern, Duane; Garg, Sanjay; Bullard, Randy

1989-01-01

A sample integrated flight/propulsion control system design is presented for the piloted longitiudinal landing task with a modern, statistically unstable fighter aircraft. The design procedure is summarized, the vehicle model used in the sample study is described, and the procedure for partitioning the integrated system is presented along with a description of the subsystems. The high-level airframe performance specifications and control design are presented and the control performance is evaluated. The generation of the low-level (engine) subsystem specifications from the airframe requirements are discussed, and the engine performance specifications are presented along with the subsystem control design. A compensator to accommodate the influence of airframe outputs on the engine subsystem is also considered. Finally, the entire closed loop system performance and stability characteristics are examined.

Decentralized approaches to wastewater treatment and management: applicability in developing countries.

PubMed

Massoud, May A; Tarhini, Akram; Nasr, Joumana A

2009-01-01

Providing reliable and affordable wastewater treatment in rural areas is a challenge in many parts of the world, particularly in developing countries. The problems and limitations of the centralized approaches for wastewater treatment are progressively surfacing. Centralized wastewater collection and treatment systems are costly to build and operate, especially in areas with low population densities and dispersed households. Developing countries lack both the funding to construct centralized facilities and the technical expertise to manage and operate them. Alternatively, the decentralized approach for wastewater treatment which employs a combination of onsite and/or cluster systems is gaining more attention. Such an approach allows for flexibility in management, and simple as well as complex technologies are available. The decentralized system is not only a long-term solution for small communities but is more reliable and cost effective. This paper presents a review of the various decentralized approaches to wastewater treatment and management. A discussion as to their applicability in developing countries, primarily in rural areas, and challenges faced is emphasized all through the paper. While there are many impediments and challenges towards wastewater management in developing countries, these can be overcome by suitable planning and policy implementation. Understanding the receiving environment is crucial for technology selection and should be accomplished by conducting a comprehensive site evaluation process. Centralized management of the decentralized wastewater treatment systems is essential to ensure they are inspected and maintained regularly. Management strategies should be site specific accounting for social, cultural, environmental and economic conditions in the target area.

Satellite Power System (SPS) centralization/decentralization

NASA Technical Reports Server (NTRS)

Naisbitt, J.

1978-01-01

The decentralization of government in the United States of America is described and its effect on the solution of energy problems is given. The human response to the introduction of new technologies is considered as well as the behavioral aspects of multiple options.

Simulation of disturbance rejection control of half-car active suspension system using active disturbance rejection control with decoupling transformation

NASA Astrophysics Data System (ADS)

Hasbullah, Faried; Faris, Waleed F.

2017-12-01

In recent years, Active Disturbance Rejection Control (ADRC) has become a popular control alternative due to its easy applicability and robustness to varying processes. In this article, ADRC with input decoupling transformation (ADRC-IDT) is proposed to improve ride comfort of a vehicle with an active suspension system using half-car model. The ride performance of the ADRC-IDT is evaluated and compared with decentralized ADRC control as well as the passive system. Simulation results show that both ADRC and ADRC-IDT manage to appreciably reduce body accelerations and able to cope well with varying conditions typically encountered in an active suspension system. Also, it is sufficient to control only the body motions with both active controllers to improve ride comfort while maintaining good road holding and small suspension working space.

Field-scale electrolysis/ceramic membrane system for the treatment of sewage from decentralized small communities.

PubMed

Son, Dong-Jin; Kim, Woo-Yeol; Yun, Chan-Young; Kim, Dae-Gun; Chang, Duk; Sunwoo, Young; Hong, Ki-Ho

2017-07-05

The electrolysis process adopting copper electrodes and ceramic membrane with pore sizes of 0.1-0.2 μm were consisted to a system for the treatment of sewage from decentralized small communities. The system was operated under an HRT of 0.1 hour, voltage of 24 V, and TMP of 0.05 MPa. The system showed average removals of organics, nitrogen, phosphorus, and solids of up to 80%, 52%, 92%, and 100%, respectively. Removal of organics and nitrogen dramatically increased in proportion to increment of influent loading. Phosphorus and solids were remarkably eliminated by both electro-coagulation and membrane filtration. The residual particulate constituents could also be removed successfully through membrane process. A system composed of electrolysis process with ceramic membrane would be a compact, reliable, and flexible option for the treatment of sewage from decentralized small communities.

[Significant changes in the health system decentralization process in Brazil].

PubMed

Viana, Ana Luiza d'Avila; Heimann, Luiza S; de Lima, Luciana Dias; de Oliveira, Roberta Gondim; Rodrigues, Sergio da Hora

2002-01-01

This article discusses the trends and limits of the Brazilian health system decentralization process, identifying the three elements that constitute the strategic induction performed by the national system administrator in accordance with the guidelines contained in the Operational Norms of the Unified National Health System: systemic rationality, intergovernmental and service provider financing, and health care model. The effects of the Federal regulations are analyzed based on the results of the evaluation study focused on the implementation of the full management scheme at the Municipal level. The decentralization strategy induced by Basic Operational Norm 96 has succeeded in improving institutional conditions, management autonomy, and supply, as measured by the Federal resources transferred, installed capacity, production, and coverage of outpatient and hospital services, with the Municipalities authorized to conduct fully autonomous management, without altering the existing patterns of inequity in the distribution of funds to poorer Municipalities.

Governing decentralization in health care under tough budget constraint: what can we learn from the Italian experience?

PubMed

Tediosi, Fabrizio; Gabriele, Stefania; Longo, Francesco

2009-05-01

In many European countries, since the World War II, there has been a trend towards decentralization of health policy to lower levels of governments, while more recently there have been re-centralization processes. Whether re-centralization will be the new paradigm of European health policy or not is difficult to say. In the Italian National Health Service (SSN) decentralization raised two related questions that might be interesting for the international debate on decentralization in health care: (a) what sort of regulatory framework and institutional balances are required to govern decentralization in health care in a heterogeneous country under tough budget constraints? (b) how can it be ensured that the most advanced parts of the country remain committed to solidarity, supporting the weakest ones? To address these questions this article describes the recent trends in SSN funding and expenditure, it reviews the strategy adopted by the Italian government for governing the decentralization process and discusses the findings to draw policy conclusions. The main lessons emerging from this experience are that: (1) when the differences in administrative and policy skills, in socio-economic standards and social capital are wide, decentralization may lead to undesirable divergent evolution paths; (2) even in decentralized systems, the role of the Central government can be very important to contain health expenditure; (3) a strong governance of the Central government may help and not hinder the enforcement of decentralization; and (4) supporting the weakest Regions and maintaining inter-regional solidarity is hard but possible. In Italy, despite an increasing role of the Central government in steering the SSN, the pattern of regional decentralization of health sector decision making does not seem at risk. Nevertheless, the Italian case confirms the complexity of decentralization and re-centralization processes that sometimes can be paradoxically reinforcing each other.

Health sector decentralization and local decision-making: Decision space, institutional capacities and accountability in Pakistan.

PubMed

Bossert, Thomas John; Mitchell, Andrew David

2011-01-01

Health sector decentralization has been widely adopted to improve delivery of health services. While many argue that institutional capacities and mechanisms of accountability required to transform decentralized decision-making into improvements in local health systems are lacking, few empirical studies exist which measure or relate together these concepts. Based on research instruments administered to a sample of 91 health sector decision-makers in 17 districts of Pakistan, this study analyzes relationships between three dimensions of decentralization: decentralized authority (referred to as "decision space"), institutional capacities, and accountability to local officials. Composite quantitative indicators of these three dimensions were constructed within four broad health functions (strategic and operational planning, budgeting, human resources management, and service organization/delivery) and on an overall/cross-function basis. Three main findings emerged. First, district-level respondents report varying degrees of each dimension despite being under a single decentralization regime and facing similar rules across provinces. Second, within dimensions of decentralization-particularly decision space and capacities-synergies exist between levels reported by respondents in one function and those reported in other functions (statistically significant coefficients of correlation ranging from ρ=0.22 to ρ=0.43). Third, synergies exist across dimensions of decentralization, particularly in terms of an overall indicator of institutional capacities (significantly correlated with both overall decision space (ρ=0.39) and accountability (ρ=0.23)). This study demonstrates that decentralization is a varied experience-with some district-level officials making greater use of decision space than others and that those who do so also tend to have more capacity to make decisions and are held more accountable to elected local officials for such choices. These findings suggest that Pakistan's decentralization policy should focus on synergies among dimensions of decentralization to encouraging more use of de jure decision space, work toward more uniform institutional capacity, and encourage greater accountability to local elected officials. Copyright © 2010 Elsevier Ltd. All rights reserved.

Evolutionary Concepts for Decentralized Air Traffic Flow Management

NASA Technical Reports Server (NTRS)

Adams, Milton; Kolitz, Stephan; Milner, Joseph; Odoni, Amedeo

1997-01-01

Alternative concepts for modifying the policies and procedures under which the air traffic flow management system operates are described, and an approach to the evaluation of those concepts is discussed. Here, air traffic flow management includes all activities related to the management of the flow of aircraft and related system resources from 'block to block.' The alternative concepts represent stages in the evolution from the current system, in which air traffic management decision making is largely centralized within the FAA, to a more decentralized approach wherein the airlines and other airspace users collaborate in air traffic management decision making with the FAA. The emphasis in the discussion is on a viable medium-term partially decentralized scenario representing a phase of this evolution that is consistent with the decision-making approaches embodied in proposed Free Flight concepts for air traffic management. System-level metrics for analyzing and evaluating the various alternatives are defined, and a simulation testbed developed to generate values for those metrics is described. The fundamental issue of modeling airline behavior in decentralized environments is also raised, and an example of such a model, which deals with the preservation of flight bank integrity in hub airports, is presented.

Robust decentralized control laws for the ACES structure

NASA Technical Reports Server (NTRS)

Collins, Emmanuel G., Jr.; Phillips, Douglas J.; Hyland, David C.

1991-01-01

Control system design for the Active Control Technique Evaluation for Spacecraft (ACES) structure at NASA Marshall Space Flight Center is discussed. The primary objective of this experiment is to design controllers that provide substantial reduction of the line-of-sight pointing errors. Satisfaction of this objective requires the controllers to attenuate beam vibration significantly. The primary method chosen for control design is the optimal projection approach for uncertain systems (OPUS). The OPUS design process allows the simultaneous tradeoff of five fundamental issues in control design: actuator sizing, sensor accuracy, controller order, robustness, and system performance. A brief description of the basic ACES configuration is given. The development of the models used for control design and control design for eight system loops that were selected by analysis of test data collected from the structure are discussed. Experimental results showing that very significant performance improvement is achieved when all eight feedback loops are closed are presented.

Primary Health Care and tuberculosis: services evaluation.

PubMed

Wysocki, Anneliese Domingues; Ponce, Maria Amélia Zanon; Brunello, Maria Eugênia Firmino; Beraldo, Aline Ale; Vendramini, Silvia Helena Figueiredo; Scatena, Lúcia Marina; Ruffino, Antonio; Villa, Tereza Cristina Scatena

2017-01-01

In order to control tuberculosis, the Brazilian Ministry of Health recommends the decentralization of control actions directed to the Primary Health Care, and there are few studies on the performance of the Tuberculosis Control Program in decentralized contexts. To evaluate the performance of Primary Health Care services in tuberculosis treatment. This is an evaluative study with cross-sectional approach conducted in 2011. Two hundred and thirty-nine health professionals from Primary Health Care units were interviewed using a structured instrument based on the evaluation reference of the health services quality (structure - process - results). The performance of these services was analyzed applying techniques of descriptive statistics, validation, and construction of indicators and by determining the reduced variable "Z". The indicators "participation of professionals in tuberculosis patients' care" (structure) and "reference and counterreference" (process) had the best evaluations, whereas "professional training" (structure) and "external actions for tuberculosis control" (process) had the worst results. The decentralization of tuberculosis control actions has been taking place in a vertical manner in Primary Health Care. The challenge of controlling tuberculosis involves overcoming constraints related to the engagement, training, and turnover rates among health professionals, which is a coordination between services and monitoring of control actions in Primary Health Care.

The impact of federalism on the healthcare system in terms of efficiency, equity, and cost containment: the case of Switzerland.

PubMed

Crivelli, Luca; Salari, Paola

2014-01-01

According to the economic theory of federalism (Oates 1999), a decentralized decision to collectively fund and supply the quantity and quality of public services will increase economic welfare as long as three conditions are fulfilled: preferences and production costs of the different local constituencies are heterogeneous; local governments are better informed than the central agency because of their proximity to the citizens; and the competition between local governments exerts a significant impact on the performance of the local administration and on the ability of public agencies to implement policy innovation. Federalism also presents some negative aspects, including the opportunity costs of decentralization, which materialize in terms of unexploited economies of scale; the emergence of spillover effects among jurisdictions; and the risk of cost-shifting exercises from one layer of the government to the other. Finally, competition between fiscal regimes can affect the level of equity. The literature considers fiscal federalism as a mechanism for controlling the size of the public sector and for constraining the development of redistributive measures. The present paper reviews the impact that federalism has on the efficiency, equity, and cost containment of the healthcare system in Switzerland, a country with a strongly decentralized political system that is based on federalism and the institutions of direct democracy, a liberal economic culture, and a well-developed tradition of mutualism and social security (generous social expenditure and welfare system). By analyzing the empirical evidence available for Switzerland, we expect to draw some general policy lessons that might also be useful for other countries.

Decentralized Control of Scheduling in Distributed Systems.

DTIC Science & Technology

1983-03-18

the job scheduling algorithm adapts to the changing busyness of the various hosts in the system. The environment in which the job scheduling entities...resources and processes that constitute the node and a set of interfaces for accessing these processes and resources. The structure of a node could change ...parallel. Chang [CHNG82] has also described some algorithms for detecting properties of general graphs by traversing paths in a graph in parallel. One of

Decentralized Control of Scheduling in Distributed Systems.

DTIC Science & Technology

1983-12-15

does not perform quite as well as the 10 state system, but is less sensitive to changes in scheduling period. It performs best when scheduling is...intra-process concerns. We extend theLr concept of a process to inolude Inter -ress comunication. That is. various form of send and receive primitives...Current busyness of each site based on some responses to requests for bids. A received bid is utilization factor. adjusted by incrementing it by a

The Organization of Correctional Education Services

ERIC Educational Resources Information Center

Gehring, Thom

2007-01-01

There have been five major types of correctional education organizations over the centuries: Sabbath school, traditional or decentralized, bureau, correctional school district (CSD), and integral education. The middle three are modern organizational patterns that can be implemented throughout a system: Decentralized, bureau, and CSD. The…

Regionalism, Devolution and Education

ERIC Educational Resources Information Center

Bogdanor, Vernon

1977-01-01

Described are effects of political decentralization in the United Kingdom on political and social institutions, particularly education. The author concludes that regionalism could yield advantages of power decentralization, diversity of decision making, and educational systems which are more closely connected to regional and local traditions.…

The Riccati equation, imprimitive actions and symplectic forms. [with application to decentralized optimal control problem

NASA Technical Reports Server (NTRS)

Garzia, M. R.; Loparo, K. A.; Martin, C. F.

1982-01-01

This paper looks at the structure of the solution of a matrix Riccati differential equation under a predefined group of transformations. The group of transformations used is an expanded form of the feedback group. It is shown that this group of transformations is a subgroup of the symplectic group. The orbits of the Riccati differential equation under the action of this group are studied and it is seen how these techniques apply to a decentralized optimal control problem.

The path dependence of district manager decision-space in Ghana

PubMed Central

Kwamie, Aku; van Dijk, Han; Ansah, Evelyn K; Agyepong, Irene Akua

2016-01-01

The district health system in Ghana today is characterized by high resource-uncertainty and narrow decision-space. This article builds a theory-driven historical case study to describe the influence of path-dependent administrative, fiscal and political decentralization processes on development of the district health system and district manager decision-space. Methods included a non-exhaustive literature review of democratic governance in Ghana, and key informant interviews with high-level health system officials integral to the development of the district health system. Through our analysis we identified four periods of district health system progression: (1) development of the district health system (1970–85); (2) Strengthening District Health Systems Initiative (1986–93); (3) health sector reform planning and creation of the Ghana Health Service (1994–96) and (4) health sector reform implementation (1997–2007). It was observed that district manager decision-space steadily widened during periods (1) and (2), due to increases in managerial profile, and concerted efforts at managerial capacity strengthening. Periods (3) and (4) saw initial augmentation of district health system financing, further widening managerial decision-space. However, the latter half of period 4 witnessed district manager decision-space contraction. Formalization of Ghana Health Service structures influenced by self-reinforcing tendencies towards centralized decision-making, national and donor shifts in health sector financing, and changes in key policy actors all worked to the detriment of the district health system, reversing early gains from bottom-up development of the district health system. Policy feedback mechanisms have been influenced by historical and contemporary sequencing of local government and health sector decentralization. An initial act of administrative decentralization, followed by incomplete political and fiscal decentralization has ensured that the balance of power has remained at national level, with strong vertical accountabilities and dependence of the district on national level. This study demonstrates that the rhetoric of decentralization does not always mirror actual implementation, nor always result in empowered local actors. PMID:26318537

A decentralized mechanism for improving the functional robustness of distribution networks.

PubMed

Shi, Benyun; Liu, Jiming

2012-10-01

Most real-world distribution systems can be modeled as distribution networks, where a commodity can flow from source nodes to sink nodes through junction nodes. One of the fundamental characteristics of distribution networks is the functional robustness, which reflects the ability of maintaining its function in the face of internal or external disruptions. In view of the fact that most distribution networks do not have any centralized control mechanisms, we consider the problem of how to improve the functional robustness in a decentralized way. To achieve this goal, we study two important problems: 1) how to formally measure the functional robustness, and 2) how to improve the functional robustness of a network based on the local interaction of its nodes. First, we derive a utility function in terms of network entropy to characterize the functional robustness of a distribution network. Second, we propose a decentralized network pricing mechanism, where each node need only communicate with its distribution neighbors by sending a "price" signal to its upstream neighbors and receiving "price" signals from its downstream neighbors. By doing so, each node can determine its outflows by maximizing its own payoff function. Our mathematical analysis shows that the decentralized pricing mechanism can produce results equivalent to those of an ideal centralized maximization with complete information. Finally, to demonstrate the properties of our mechanism, we carry out a case study on the U.S. natural gas distribution network. The results validate the convergence and effectiveness of our mechanism when comparing it with an existing algorithm.

Organizational Systems Theory and Command and Control Concepts

DTIC Science & Technology

2013-03-01

Decentralized C2 • Problem is determinable • Many solutions • Predictable results • Low Risk • Slow feedback loop • Plans: Engineered or designed • C2...of these concepts in the Art of Command and the Science of Control, but lacks a proper model to assist commanders in determining how to correctly...commanders in determining how to correctly apply the concepts based on the operational environment. The paper concludes with a recommendation that the

Politics of Decision Making in Relation to Education in Comparative Perspective, Unity and Diversity as a Problem. Centralization and Decentralization in Decision Making: The Lay Board of Control.

ERIC Educational Resources Information Center

Pfnister, Allan O.

The evolution and role of the lay board of control (trustees, directors) of higher educational institutions and the part the board has played or may play in maintaining diversity in the American system are examined. The evolution of the lay board in the United States and in the United Kingdom is described. The lay board has become "the…

California's Transition to the Common Core State Standards: The State's Role in Local Capacity Building

ERIC Educational Resources Information Center

Warren, Paul; Murphy, Patrick

2014-01-01

The Common Core State Standards (CCSS) and the Local Control Funding Formula are introducing major changes to California's K-12 system. Implementation of new curricula and instruction is under way at the district level, but California started its transition relatively late and it has taken a more decentralized approach than most other states.…

Black, White, Green, Red. The Politics of Education in Ethnic America.

ERIC Educational Resources Information Center

Bresnick, David; And Others

The upheaval in large city school systems during the late 1960s and early 1970s is examined in this book. Most of the specific examples are drawn from school districts in New York City, such as Ocean Hill-Brownsville and Canarsie. The problems of growing demands for community control, ethnic and racial conflicts, and school decentralization are…

Analysis of Decentralized Variable Structure Control for Collective Search by Mobile Robots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feddema, J.; Goldsmith, S.; Robinett, R.

1998-11-04

This paper presents an analysis of a decentralized coordination strategy for organizing and controlling a team of mobile robots performing collective search. The alpha-beta coordination strategy is a family of collective search algorithms that allow teams of communicating robots to implicitly coordinate their search activities through a division of labor based on self-selected roIes. In an alpha-beta team. alpha agents are motivated to improve their status by exploring new regions of the search space. Beta a~ents are conservative, and reiy on the alpha agents to provide advanced information on favorable regions of the search space. An agent selects its currentmore » role dynamically based on its current status value relative to the current status values of the other team members. Status is determined by some function of the agent's sensor readings, and is generally a measurement of source intensity at the agent's current location. Variations on the decision rules determining alpha and beta behavior produce different versions of the algorithm that lead to different global properties. The alpha-beta strategy is based on a simple finite-state machine that implements a form of Variable Structure Control (VSC). The VSC system changes the dynamics of the collective system by abruptly switching at defined states to alternative control laws . In VSC, Lyapunov's direct method is often used to design control surfaces which guide the system to a given goal. We introduce the alpha-beta aIgorithm and present an analysis of the equilibrium point and the global stability of the alpha-beta algorithm based on Lyapunov's method.« less

Analysis of decentralized variable structure control for collective search by mobile robots

NASA Astrophysics Data System (ADS)

Goldsmith, Steven Y.; Feddema, John T.; Robinett, Rush D., III

1998-10-01

This paper presents an analysis of a decentralized coordination strategy for organizing and controlling a team of mobile robots performing collective search. The alpha- beta coordination strategy is a family of collective search algorithms that allow teams of communicating robots to implicitly coordinate their search activities through a division of labor based on self-selected roles. In an alpha- beta team, alpha agents are motivated to improve their status by exploring new regions of the search space. Beta agents are conservative, and rely on the alpha agents to provide advanced information on favorable regions of the search space. An agent selects its current role dynamically based on its current status value relative to the current status values of the other team members. Status is determined by some function of the agent's sensor readings, and is generally a measurement of source intensity at the agent's current location. Variations on the decision rules determining alpha and beta behavior produce different versions of the algorithm that lead to different global properties. The alpha-beta strategy is based on a simple finite-state machine that implements a form of Variable Structure Control (VSC). The VSC system changes the dynamics of the collective system by abruptly switching at defined states to alternative control laws. In VSC, Lyapunov's direct method is often used to design control surfaces which guide the system to a given goal. We introduce the alpha- beta algorithm and present an analysis of the equilibrium point and the global stability of the alpha-beta algorithm based on Lyapunov's method.

Distributed Environment Control Using Wireless Sensor/Actuator Networks for Lighting Applications

PubMed Central

Nakamura, Masayuki; Sakurai, Atsushi; Nakamura, Jiro

2009-01-01

We propose a decentralized algorithm to calculate the control signals for lights in wireless sensor/actuator networks. This algorithm uses an appropriate step size in the iterative process used for quickly computing the control signals. We demonstrate the accuracy and efficiency of this approach compared with the penalty method by using Mote-based mesh sensor networks. The estimation error of the new approach is one-eighth as large as that of the penalty method with one-fifth of its computation time. In addition, we describe our sensor/actuator node for distributed lighting control based on the decentralized algorithm and demonstrate its practical efficacy. PMID:22291525

Guidance for School Improvement in a Decentralizing System: How Much, What Kind and from Where? Children Achieving: Philadelphia's Education Reform. Progress Report Series 1996-1997.

ERIC Educational Resources Information Center

Christman, Jolley Bruce

Philadelphia's school reform initiative, Children Achieving" was evaluated. The focus in this report is on decentralization, exploring how Children Achieving is strengthening schools' capacity to make and carry out informed decisions that lead to schoolwide standards, how the new structures are working at various levels of the system, and how…

Survey on large scale system control methods

NASA Technical Reports Server (NTRS)

Mercadal, Mathieu

1987-01-01

The problem inherent to large scale systems such as power network, communication network and economic or ecological systems were studied. The increase in size and flexibility of future spacecraft has put those dynamical systems into the category of large scale systems, and tools specific to the class of large systems are being sought to design control systems that can guarantee more stability and better performance. Among several survey papers, reference was found to a thorough investigation on decentralized control methods. Especially helpful was the classification made of the different existing approaches to deal with large scale systems. A very similar classification is used, even though the papers surveyed are somehow different from the ones reviewed in other papers. Special attention is brought to the applicability of the existing methods to controlling large mechanical systems like large space structures. Some recent developments are added to this survey.

Adaptive change in corporate control practices.

PubMed

Alexander, J A

1991-03-01

Multidivisional organizations are not concerned with what structure to adopt but with how they should exercise control within the divisional form to achieve economic efficiencies. Using an information-processing framework, I examined control arrangements between the headquarters and operating divisions of such organizations and how managers adapted control practices to accommodate increasing environmental uncertainty. Also considered were the moderating effects of contextual attributes on such adaptive behavior. Analyses of panel data from 97 multihospital systems suggested that organizations generally practice selective decentralization under conditions of increasing uncertainty but that organizational age, dispersion, and initial control arrangements significantly moderate the direction and magnitude of such changes.

Benefits of production extension and shifting with thermal storage for a 1MW CSP-ORC plant in Morocco

NASA Astrophysics Data System (ADS)

Bennouna, El Ghali; Mimet, Abdelaziz; Frej, Hicham

2016-05-01

The importance of thermal storage for commercial CSP (concentrated Solar Power) plants has now become obvious, this regardless of the solar technology used and the power cycle. The availability of a storage system to a plant operator brings a lot of possibilities for production management, cash flow optimization and grid stabilizing. In particular, and depending on plant location and local grid strategy, thermal storage can contribute, when wisely used, to control production and adapt it to the demand and / or power unbalances and varying prices. Storage systems design, sizing and configuration are proper to each power plant, hence systems that are now widely installed within large commercial solar plants are not necessarily suited for small scale decentralized production, and will not have the same effects. In this paper the benefits of thermal storage are studied for a 1MWe CSP plant with an ORC (Organic Rankine Cycle), this plant has many specific features which call for a detail analysis about the appropriate storage design and optimum operating strategies for decentralized solutions.

MEDLARS and the Library Community

PubMed Central

Adams, Scott

1964-01-01

The intention of the National Library of Medicine is to share with other libraries the products and the capabilities developed by the MEDLARS system. MEDLARS will provide bibliographic services of use to other libraries from the central system. The decentralization of the central system to permit libraries with access to computers to establish local machine retrieval systems is also indicated. The implications of such decentralization for the American medical library network and its effect on library evolution are suggested, as are the implications for international development of mechanized storage and retrieval systems. PMID:14119289

Resilience in social insect infrastructure systems

PubMed Central

2016-01-01

Both human and insect societies depend on complex and highly coordinated infrastructure systems, such as communication networks, supply chains and transportation networks. Like human-designed infrastructure systems, those of social insects are regularly subject to disruptions such as natural disasters, blockages or breaks in the transportation network, fluctuations in supply and/or demand, outbreaks of disease and loss of individuals. Unlike human-designed systems, there is no deliberate planning or centralized control system; rather, individual insects make simple decisions based on local information. How do these highly decentralized, leaderless systems deal with disruption? What factors make a social insect system resilient, and which factors lead to its collapse? In this review, we bring together literature on resilience in three key social insect infrastructure systems: transportation networks, supply chains and communication networks. We describe how systems differentially invest in three pathways to resilience: resistance, redirection or reconstruction. We suggest that investment in particular resistance pathways is related to the severity and frequency of disturbance. In the final section, we lay out a prospectus for future research. Human infrastructure networks are rapidly becoming decentralized and interconnected; indeed, more like social insect infrastructures. Human infrastructure management might therefore learn from social insect researchers, who can in turn make use of the mature analytical and simulation tools developed for the study of human infrastructure resilience. PMID:26962030

The School Elections: A Critique of the 1969 New York City School Decentralization.

ERIC Educational Resources Information Center

Demas, Boulton H.

When local school board members in New York City assumed office on 31 local school boards in 1969, this should have resulted in more responsive local boards with sufficient power to control local policy; but this was not the actual result. Specific examination of the decentralization bill, the politics of the election, and the election procedures…

Commentary on "Finance, Management, and Costs of Public and Private Schools in Indonesia" and "Do Local Contributions Affect the Efficiency of Public Primary Schools?"

ERIC Educational Resources Information Center

Berger, Mark C.

1996-01-01

Studies on Indonesia and the Philippines in this special issue examine how local financial control affects costs of providing primary schooling. In both countries, schools with greater financial decentralization operated more efficiently. These results have important implications for U.S. schools, where decentralization reforms in Kentucky and…

INTRAOCULAR LENS POSITION IN COMBINED PHACOEMULSIFICATION AND VITREORETINAL SURGERY.

PubMed

Ozates, Serdar; Kiziltoprak, Hasan; Koc, Mustafa; Uzel, Mehmet Murat; Teke, Mehmet Yasin

2017-10-09

To assess the decentration and angle of tilt of the intraocular lens (IOL) according to the intravitreal tamponade types used in combined phacoemulsification and vitreoretinal surgery. This prospective and randomized clinical study involved 73 eyes of 69 patients who underwent combined vitreoretinal surgery. Eyes with intravitreal tamponades formed the study group and eyes without intravitreal tamponades formed the control group. The study group was further divided into silicone oil and gas tamponade subgroups. Cross-sectional IOL images were captured using a Pentacam HR (Oculus, Germany) and tilt and decentration were calculated with Adobe Photoshop software (Adobe, San Jose, CA). The mean angle of tilt and decentration at the vertical meridian were significantly higher in both tamponade groups than in the control group (P < 0.05 for all). No significant difference was observed among the groups regarding IOL position parameters at the horizontal meridian (P > 0.05). When comparing the silicone oil and gas tamponade subgroups, no significant differences were noted on the position of IOL at both meridians (P > 0.05 for all). Intravitreal tamponades have an important effect on the position of IOL in combined vitreoretinal surgery. Silicone oil and gas tamponades may induce postoperative tilt and decentration of one-piece acrylic IOLs.

Impact of heterogeneity and socioeconomic factors on individual behavior in decentralized sharing ecosystems.

PubMed

Gavaldà-Miralles, Arnau; Choffnes, David R; Otto, John S; Sánchez, Mario A; Bustamante, Fabián E; Amaral, Luís A N; Duch, Jordi; Guimerà, Roger

2014-10-28

Tens of millions of individuals around the world use decentralized content distribution systems, a fact of growing social, economic, and technological importance. These sharing systems are poorly understood because, unlike in other technosocial systems, it is difficult to gather large-scale data about user behavior. Here, we investigate user activity patterns and the socioeconomic factors that could explain the behavior. Our analysis reveals that (i) the ecosystem is heterogeneous at several levels: content types are heterogeneous, users specialize in a few content types, and countries are heterogeneous in user profiles; and (ii) there is a strong correlation between socioeconomic indicators of a country and users behavior. Our findings open a research area on the dynamics of decentralized sharing ecosystems and the socioeconomic factors affecting them, and may have implications for the design of algorithms and for policymaking.

InkTag: Secure Applications on an Untrusted Operating System

PubMed Central

Hofmann, Owen S.; Kim, Sangman; Dunn, Alan M.; Lee, Michael Z.; Witchel, Emmett

2014-01-01

InkTag is a virtualization-based architecture that gives strong safety guarantees to high-assurance processes even in the presence of a malicious operating system. InkTag advances the state of the art in untrusted operating systems in both the design of its hypervisor and in the ability to run useful applications without trusting the operating system. We introduce paraverification, a technique that simplifies the InkTag hypervisor by forcing the untrusted operating system to participate in its own verification. Attribute-based access control allows trusted applications to create decentralized access control policies. InkTag is also the first system of its kind to ensure consistency between secure data and metadata, ensuring recoverability in the face of system crashes. PMID:24429939

First Experiences Using XACML for Access Control in Distributed Systems

NASA Technical Reports Server (NTRS)

Lorch, Marcus; Proctor, Seth; Lepro, Rebekah; Kafura, Dennis; Shah, Sumit

2003-01-01

Authorization systems today are increasingly complex. They span domains of administration, rely on many different authentication sources, and manage permissions that can be as complex as the system itself. Worse still, while there are many standards that define authentication mechanisms, the standards that address authorization are less well defined and tend to work only within homogeneous systems. This paper presents XACML, a standard access control language, as one component of a distributed and inter-operable authorization framework. Several emerging systems which incorporate XACML are discussed. These discussions illustrate how authorization can be deployed in distributed, decentralized systems. Finally, some new and future topics are presented to show where this work is heading and how it will help connect the general components of an authorization system.

InkTag: Secure Applications on an Untrusted Operating System.

PubMed

Hofmann, Owen S; Kim, Sangman; Dunn, Alan M; Lee, Michael Z; Witchel, Emmett

2013-01-01

InkTag is a virtualization-based architecture that gives strong safety guarantees to high-assurance processes even in the presence of a malicious operating system. InkTag advances the state of the art in untrusted operating systems in both the design of its hypervisor and in the ability to run useful applications without trusting the operating system. We introduce paraverification , a technique that simplifies the InkTag hypervisor by forcing the untrusted operating system to participate in its own verification. Attribute-based access control allows trusted applications to create decentralized access control policies. InkTag is also the first system of its kind to ensure consistency between secure data and metadata, ensuring recoverability in the face of system crashes.

Responsibility Center Management: A Financial Paradigm and Alternative to Decentralized Budgeting.

ERIC Educational Resources Information Center

Hensley, Phyllis A.; Bava, D. J.; Brennan, Denise C.

This study examined the implementation of Responsibility Center Management (RCM) systems in two institutions of higher education: the Graduate School of Business at Institution and the Center of Collaborative Education and Professional Studies at Institution B. RCM is a management and budgeting process for universities that decentralizes authority…

Transition-Independent Decentralized Markov Decision Processes

NASA Technical Reports Server (NTRS)

Becker, Raphen; Silberstein, Shlomo; Lesser, Victor; Goldman, Claudia V.; Morris, Robert (Technical Monitor)

2003-01-01

There has been substantial progress with formal models for sequential decision making by individual agents using the Markov decision process (MDP). However, similar treatment of multi-agent systems is lacking. A recent complexity result, showing that solving decentralized MDPs is NEXP-hard, provides a partial explanation. To overcome this complexity barrier, we identify a general class of transition-independent decentralized MDPs that is widely applicable. The class consists of independent collaborating agents that are tied up by a global reward function that depends on both of their histories. We present a novel algorithm for solving this class of problems and examine its properties. The result is the first effective technique to solve optimally a class of decentralized MDPs. This lays the foundation for further work in this area on both exact and approximate solutions.

Perturbed cooperative-state feedback strategy for model predictive networked control of interconnected systems.

PubMed

Tran, Tri; Ha, Q P

2018-01-01

A perturbed cooperative-state feedback (PSF) strategy is presented for the control of interconnected systems in this paper. The subsystems of an interconnected system can exchange data via the communication network that has multiple connection topologies. The PSF strategy can resolve both issues, the sensor data losses and the communication network breaks, thanks to the two components of the control including a cooperative-state feedback and a perturbation variable, e.g., u i =K ij x j +w i . The PSF is implemented in a decentralized model predictive control scheme with a stability constraint and a non-monotonic storage function (ΔV(x(k))≥0), derived from the dissipative systems theory. Numerical simulation for the automatic generation control problem in power systems is studied to illustrate the effectiveness of the presented PSF strategy. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Simulating the decentralized processes of the human immune system in a virtual anatomy model.

PubMed

Sarpe, Vladimir; Jacob, Christian

2013-01-01

Many physiological processes within the human body can be perceived and modeled as large systems of interacting particles or swarming agents. The complex processes of the human immune system prove to be challenging to capture and illustrate without proper reference to the spatial distribution of immune-related organs and systems. Our work focuses on physical aspects of immune system processes, which we implement through swarms of agents. This is our first prototype for integrating different immune processes into one comprehensive virtual physiology simulation. Using agent-based methodology and a 3-dimensional modeling and visualization environment (LINDSAY Composer), we present an agent-based simulation of the decentralized processes in the human immune system. The agents in our model - such as immune cells, viruses and cytokines - interact through simulated physics in two different, compartmentalized and decentralized 3-dimensional environments namely, (1) within the tissue and (2) inside a lymph node. While the two environments are separated and perform their computations asynchronously, an abstract form of communication is allowed in order to replicate the exchange, transportation and interaction of immune system agents between these sites. The distribution of simulated processes, that can communicate across multiple, local CPUs or through a network of machines, provides a starting point to build decentralized systems that replicate larger-scale processes within the human body, thus creating integrated simulations with other physiological systems, such as the circulatory, endocrine, or nervous system. Ultimately, this system integration across scales is our goal for the LINDSAY Virtual Human project. Our current immune system simulations extend our previous work on agent-based simulations by introducing advanced visualizations within the context of a virtual human anatomy model. We also demonstrate how to distribute a collection of connected simulations over a network of computers. As a future endeavour, we plan to use parameter tuning techniques on our model to further enhance its biological credibility. We consider these in silico experiments and their associated modeling and optimization techniques as essential components in further enhancing our capabilities of simulating a whole-body, decentralized immune system, to be used both for medical education and research as well as for virtual studies in immunoinformatics.

Optimal Decentralized Protocol for Electric Vehicle Charging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gan, LW; Topcu, U; Low, SH

We propose a decentralized algorithm to optimally schedule electric vehicle (EV) charging. The algorithm exploits the elasticity of electric vehicle loads to fill the valleys in electric load profiles. We first formulate the EV charging scheduling problem as an optimal control problem, whose objective is to impose a generalized notion of valley-filling, and study properties of optimal charging profiles. We then give a decentralized algorithm to iteratively solve the optimal control problem. In each iteration, EVs update their charging profiles according to the control signal broadcast by the utility company, and the utility company alters the control signal to guidemore » their updates. The algorithm converges to optimal charging profiles (that are as "flat" as they can possibly be) irrespective of the specifications (e.g., maximum charging rate and deadline) of EVs, even if EVs do not necessarily update their charging profiles in every iteration, and use potentially outdated control signal when they update. Moreover, the algorithm only requires each EV solving its local problem, hence its implementation requires low computation capability. We also extend the algorithm to track a given load profile and to real-time implementation.« less

Decentralized System Identification Using Stochastic Subspace Identification for Wireless Sensor Networks

PubMed Central

Cho, Soojin; Park, Jong-Woong; Sim, Sung-Han

2015-01-01

Wireless sensor networks (WSNs) facilitate a new paradigm to structural identification and monitoring for civil infrastructure. Conventional structural monitoring systems based on wired sensors and centralized data acquisition systems are costly for installation as well as maintenance. WSNs have emerged as a technology that can overcome such difficulties, making deployment of a dense array of sensors on large civil structures both feasible and economical. However, as opposed to wired sensor networks in which centralized data acquisition and processing is common practice, WSNs require decentralized computing algorithms to reduce data transmission due to the limitation associated with wireless communication. In this paper, the stochastic subspace identification (SSI) technique is selected for system identification, and SSI-based decentralized system identification (SDSI) is proposed to be implemented in a WSN composed of Imote2 wireless sensors that measure acceleration. The SDSI is tightly scheduled in the hierarchical WSN, and its performance is experimentally verified in a laboratory test using a 5-story shear building model. PMID:25856325

Decentralization and health resource allocation: a case study at the district level in Indonesia.

PubMed

Abdullah, Asnawi; Stoelwinder, Johannes

2008-01-01

Health resource allocation has been an issue of political debate in many health systems. However, the debate has tended to concentrate on vertical allocation from the national to regional level. Allocation within regions or institutions has been largely ignored. This study was conducted to contribute analysis to this gap. The objective was to investigate health resource allocation within District Health Offices (DHOs) and to compare the trends and patterns of several budget categories before and after decentralization. The study was conducted in three districts in the Province of Nanggroe Aceh Darussalam. Six fiscal year budgets, two before decentralization and four after, were studied. Data was collected from the Local Government Planning Office and DHOs. Results indicated that in the first year of implementing a decentralization policy, the local government budget rose sharply, particularly in the wealthiest district. In contrast, in relatively poor districts the budget was only boosted slightly. Increasing total local government budgets had a positive impact on increasing the health budget. The absolute amount of health budgets increased significantly, but by percentage did not change very much. Budgets for several projects and budget items increased significantly, but others, such as health promotion, monitoring and evaluation, and public-goods-related activities, decreased. This study concluded that decentralization in Indonesia had made a positive impact on district government fiscal capacity and had affected DHO budgets positively. However, an imbalanced budget allocation between projects and budget items was obvious, and this needs serious attention from policy makers. Otherwise, decentralization will not significantly improve the health system in Indonesia.

Game-Based Virtual Worlds as Decentralized Virtual Activity Systems

NASA Astrophysics Data System (ADS)

Scacchi, Walt

There is widespread interest in the development and use of decentralized systems and virtual world environments as possible new places for engaging in collaborative work activities. Similarly, there is widespread interest in stimulating new technological innovations that enable people to come together through social networking, file/media sharing, and networked multi-player computer game play. A decentralized virtual activity system (DVAS) is a networked computer supported work/play system whose elements and social activities can be both virtual and decentralized (Scacchi et al. 2008b). Massively multi-player online games (MMOGs) such as World of Warcraft and online virtual worlds such as Second Life are each popular examples of a DVAS. Furthermore, these systems are beginning to be used for research, deve-lopment, and education activities in different science, technology, and engineering domains (Bainbridge 2007, Bohannon et al. 2009; Rieber 2005; Scacchi and Adams 2007; Shaffer 2006), which are also of interest here. This chapter explores two case studies of DVASs developed at the University of California at Irvine that employ game-based virtual worlds to support collaborative work/play activities in different settings. The settings include those that model and simulate practical or imaginative physical worlds in different domains of science, technology, or engineering through alternative virtual worlds where players/workers engage in different kinds of quests or quest-like workflows (Jakobsson 2006).

Adaptive Fuzzy Output-Constrained Fault-Tolerant Control of Nonlinear Stochastic Large-Scale Systems With Actuator Faults.

PubMed

Li, Yongming; Ma, Zhiyao; Tong, Shaocheng

2017-09-01

The problem of adaptive fuzzy output-constrained tracking fault-tolerant control (FTC) is investigated for the large-scale stochastic nonlinear systems of pure-feedback form. The nonlinear systems considered in this paper possess the unstructured uncertainties, unknown interconnected terms and unknown nonaffine nonlinear faults. The fuzzy logic systems are employed to identify the unknown lumped nonlinear functions so that the problems of structured uncertainties can be solved. An adaptive fuzzy state observer is designed to solve the nonmeasurable state problem. By combining the barrier Lyapunov function theory, adaptive decentralized and stochastic control principles, a novel fuzzy adaptive output-constrained FTC approach is constructed. All the signals in the closed-loop system are proved to be bounded in probability and the system outputs are constrained in a given compact set. Finally, the applicability of the proposed controller is well carried out by a simulation example.

Decentralized adaptive control of manipulators - Theory, simulation, and experimentation

NASA Technical Reports Server (NTRS)

Seraji, Homayoun

1989-01-01

The author presents a simple decentralized adaptive-control scheme for multijoint robot manipulators based on the independent joint control concept. The control objective is to achieve accurate tracking of desired joint trajectories. The proposed control scheme does not use the complex manipulator dynamic model, and each joint is controlled simply by a PID (proportional-integral-derivative) feedback controller and a position-velocity-acceleration feedforward controller, both with adjustable gains. Simulation results are given for a two-link direct-drive manipulator under adaptive independent joint control. The results illustrate trajectory tracking under coupled dynamics and varying payload. The proposed scheme is implemented on a MicroVAX II computer for motion control of the three major joints of a PUMA 560 arm. Experimental results are presented to demonstrate that trajectory tracking is achieved despite coupled nonlinear joint dynamics.

Cross Feedback Control of a Magnetic Bearing System: Controller Design Considering Gyroscopic Effects

NASA Technical Reports Server (NTRS)

Ahrens, Markus; Kucera, Ladislav

1996-01-01

For flywheel rotors or other rotors with significant ratios of moments of inertia, the influence of gyroscopic effects has to be considered. While conservative or damped systems remain stable even under gyroscopic effects, magnetically suspended rotors can be destabilized with increasing rotational speed. The influence of gyroscopic effects on the stability and behavior of a magnetic bearing system is analyzed. The analysis is carried out with a rigid body model for the rotor and a nonlinear model for the magnetic bearing and its amplifier. Cross feedback control can compensate gyroscopic effects. This compensation leads to better system performance and can avoid instability. Furthermore, the implementation of this compensation is simple. The main structure of a decentralized controller can still be used. It has only to be expanded by the cross feedback path.

Impact of heterogeneity and socioeconomic factors on individual behavior in decentralized sharing ecosystems

PubMed Central

Gavaldà-Miralles, Arnau; Choffnes, David R.; Otto, John S.; Sánchez, Mario A.; Bustamante, Fabián E.; Amaral, Luís A. N.; Duch, Jordi; Guimerà, Roger

2014-01-01

Tens of millions of individuals around the world use decentralized content distribution systems, a fact of growing social, economic, and technological importance. These sharing systems are poorly understood because, unlike in other technosocial systems, it is difficult to gather large-scale data about user behavior. Here, we investigate user activity patterns and the socioeconomic factors that could explain the behavior. Our analysis reveals that (i) the ecosystem is heterogeneous at several levels: content types are heterogeneous, users specialize in a few content types, and countries are heterogeneous in user profiles; and (ii) there is a strong correlation between socioeconomic indicators of a country and users behavior. Our findings open a research area on the dynamics of decentralized sharing ecosystems and the socioeconomic factors affecting them, and may have implications for the design of algorithms and for policymaking. PMID:25288755

Issues concerning centralized versus decentralized power deployment

NASA Technical Reports Server (NTRS)

Metcalf, Kenneth J.; Harty, Richard B.; Robin, James F.

1991-01-01

The results of a study of proposed lunar base architectures to identify issues concerning centralized and decentralized power system deployment options are presented. The power system consists of the energy producing system (power plant), the power conditioning components used to convert the generated power into the form desired for transmission, the transmission lines that conduct this power from the power sources to the loads, and the primary power conditioning hardware located at the user end. Three power system architectures, centralized, hybrid, and decentralized, were evaluated during the course of this study. Candidate power sources were characterized with respect to mass and radiator area. Two electrical models were created for each architecture to identify the preferred method of power transmission, dc or ac. Each model allowed the transmission voltage level to be varied at assess the impact on power system mass. The ac power system models also permitted the transmission line configurations and placements to determine the best conductor construction and installation location. Key parameters used to evaluate each configuration were power source and power conditioning component efficiencies, masses, and radiator areas; transmission line masses and operating temperatures; and total system mass.

Decentralized Stackelberg Strategies for Interconnected Stochastic Dynamic Systems

DTIC Science & Technology

1977-10-01

Solutions" IM, Vol.8, No.6, p.413- 430, 1971. (42) Rhodes, I.B., and Luenberger, D.G., "Differential Games with Imperfect State Information", E Trans...34, Proc. Systems E for Power, ERDA Conf. Henniker, New Hampshire, 1975. [47) Starr, A.W., and Ho, Y.C., "Nonzero-Sum Differential Games ", Jt_., [ Vol.3, p...CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE October, 1977 Joint Services Electronics Program ,3. NUMSEROWPAGES 97 14. MONITORiNG &GENCY NAME 1

A VLF-based technique in applications to digital control of nonlinear hybrid multirate systems

NASA Astrophysics Data System (ADS)

Vassilyev, Stanislav; Ulyanov, Sergey; Maksimkin, Nikolay

2017-01-01

In this paper, a technique for rigorous analysis and design of nonlinear multirate digital control systems on the basis of the reduction method and sublinear vector Lyapunov functions is proposed. The control system model under consideration incorporates continuous-time dynamics of the plant and discrete-time dynamics of the controller and takes into account uncertainties of the plant, bounded disturbances, nonlinear characteristics of sensors and actuators. We consider a class of multirate systems where the control update rate is slower than the measurement sampling rates and periodic non-uniform sampling is admitted. The proposed technique does not use the preliminary discretization of the system, and, hence, allows one to eliminate the errors associated with the discretization and improve the accuracy of analysis. The technique is applied to synthesis of digital controller for a flexible spacecraft in the fine stabilization mode and decentralized controller for a formation of autonomous underwater vehicles. Simulation results are provided to validate the good performance of the designed controllers.

Educational Reform in South Africa: Decentralization and Parent Engagement

ERIC Educational Resources Information Center

Joubert, Rika; van Rooyen, Jean W.

2011-01-01

The promulgation of the South African Schools Act in 1996 was a critical moment in the process of making a compromise between a centralized and a decentralized system. The act describes the establishment, membership, and responsibilities of school governing bodies as the vehicle for parental engagement and decision making. The article touches on…

Decentralized Decisionmaking for Schools: New Promise for an Old Idea?

ERIC Educational Resources Information Center

Hansen, Janet S.; Roza, Marguerite

2005-01-01

Interest in decentralized decisionmaking for schools (DDS) is on the rise. With state and federal accountability systems placing pressure on school-level leaders to improve student performance, increasing attention is being paid to the question of how to help principals do their job more effectively. "Business as usual" in American…

Chronicling Decentralization Initiatives in the Philippine Basic Education Sector

ERIC Educational Resources Information Center

de Guzman, Allan B.

2007-01-01

The Philippine school system is considered as one of the largest in the world with 41,989 public elementary and secondary schools and 7790 private schools under the supervision and regulation of the Department of Education (DepEd Fact Sheet, 2005). This paper chronicles various decentralization initiatives carried out by the basic education sector…

Empowerment or Impediment? School Governance in the School-Based Management Era in Hong Kong

ERIC Educational Resources Information Center

Kwan, Paula; Li, Benjamin Yuet-man

2015-01-01

Following the international trend in education towards democracy and decentralization, the Hong Kong government introduced a school-based management (SBM) system about two decades ago. It is widely recognized in the literature that decentralization, empowering school level management and marginalizing the influence of the intermediate level of…

Decentralization of Educational Development Reforms in Nigeria: A Comparative Perspective

ERIC Educational Resources Information Center

Ikoya, Peter O.

2007-01-01

Purpose: The purpose of this paper is to seek to appraise regional compliance to decentralization laws establishing Education Boards and Committees since the Nigerian Government has for some time now been making efforts aimed at reforming her educational system. Design/methodology/approach: Employing ex post facto design, the study uses survey…

Upgrade of the HET segment control system, utilizing state-of-the-art, decentralized and embedded system controllers

NASA Astrophysics Data System (ADS)

Häuser, Marco; Richter, Josef; Kriel, Herman; Turbyfill, Amanda; Buetow, Brent; Ward, Michael

2016-07-01

Together with the ongoing major instrument upgrade of the Hobby-Eberly Telescope (HET) we present the planned upgrade of the HET Segment Control System (SCS) to SCS2. Because HET's primary mirror is segmented into 91 individual 1-meter hexagonal mirrors, the SCS is essential to maintain the mirror alignment throughout an entire night of observations. SCS2 will complete tip, tilt and piston corrections of each mirror segment at a significantly higher rate than the original SCS. The new motion control hardware will further increase the system's reliability. The initial optical measurements of this array are performed by the Mirror Alignment Recovery System (MARS) and the HET Extra Focal Instrument (HEFI). Once the segments are optically aligned, the inductive edge sensors give sub-micron precise feedback of each segment's positions relative to its adjacent segments. These sensors are part of the Segment Alignment Maintenance System (SAMS) and are responsible for providing information about positional changes due to external influences, such as steep temperature changes and mechanical stress, and for making compensatory calculations while tracking the telescope on sky. SCS2 will use the optical alignment systems and SAMS inputs to command corrections of every segment in a closed loop. The correction period will be roughly 30 seconds, mostly due to the measurement and averaging process of the SAMS algorithm. The segment actuators will be controlled by the custom developed HET Segment MOtion COntroller (SMOCO). It is a direct descendant of University Observatory Munich's embedded, CAN-based system and instrument control tool-kit. To preserve the existing HET hardware layout, each SMOCO will control two adjacent mirror segments. Unlike the original SCS motor controllers, SMOCO is able to drive all six axes of its two segments at the same time. SCS2 will continue to allow for sub-arcsecond precision in tip and tilt as well as sub-micro meter precision in piston. These estimations are based on the current performance of the segment support mechanics. SMOCO's smart motion control allows for on-the-y correction of the move targets. Since SMOCO uses state-of-the-art motion control electronics and embedded decentralized controllers, we expect reduction in thermal emission as well as less maintenance time.

Prevention of blood-borne HIV transmission using a decentralized approach in Shaba, Zaire.

PubMed

Laleman, G; Magazani, K; Perriëns, J H; Badibanga, N; Kapila, N; Konde, M; Selemani, U; Piot, P

1992-11-01

To prevent blood transfusion-acquired HIV infection with a decentralized approach to HIV screening of blood donors, using an instrument-free rapid test. Shaba province, Zaire (496,877 km2). The programme consisted of training health-care workers, distribution of a rapid HIV-antibody test (DuPont's HIVCHEK) for screening of all blood donations, and quality control of testing by a regional reference centre. Over a 2-year period, 11,940 rapid tests were distributed to 37 hospitals, covering 75% of all hospital beds outside the copper mine's health system in Shaba. Eighty-five per cent of the tests were used to screen blood donors (5.4% positive test rate) and 13% to test patients (39.7% positive test rate). At least 265 cases of HIV-positive blood donation were prevented, at an estimated cost of 137-279 ECU per case. Only 26% of initially positive specimens reached the central laboratory for supplemental testing, and sterile transfusion equipment and blood-grouping reagents were frequently unavailable. The lack of transport and communications and a deteriorating health system were major constraints. District hospitals in Africa are often long distances from major cities, difficult to reach for most of the year, and perform a small number of transfusions. In this context a classical centralized regional blood bank may not be a feasible option to ensure safe blood transfusions. However, safe blood transfusion can be achieved with a decentralized approach using a rapid test, provided that minimum standards of health-care services are available.

Enhanced drinking water supply through harvested rainwater treatment

NASA Astrophysics Data System (ADS)

Naddeo, Vincenzo; Scannapieco, Davide; Belgiorno, Vincenzo

2013-08-01

Decentralized drinking water systems represent an important element in the process of achieving the Millennium Development Goals, as centralized systems are often inefficient or nonexistent in developing countries. In those countries, most water quality related problems are due to hygiene factors and pathogens. A potential solution might include decentralized systems, which might rely on thermal and/or UV disinfection methods as well as physical and chemical treatments to provide drinking water from rainwater. For application in developing countries, decentralized systems major constraints include low cost, ease of use, environmental sustainability, reduced maintenance and independence from energy sources. This work focuses on an innovative decentralized system that can be used to collect and treat rainwater for potable use (drinking and cooking purposes) of a single household, or a small community. The experimented treatment system combines in one compact unit a Filtration process with an adsorption step on GAC and a UV disinfection phase in an innovative design (FAD - Filtration Adsorption Disinfection). All tests have been carried out using a full scale FAD treatment unit. The efficiency of FAD technology has been discussed in terms of pH, turbidity, COD, TOC, DOC, Escherichia coli and Total coliforms. FAD technology is attractive since it provides a total barrier for pathogens and organic contaminants, and reduces turbidity, thus increasing the overall quality of the water. The FAD unit costs are low, especially if compared to other water treatment technologies and could become a viable option for developing countries.

Values of decentralized systems that avoid investments in idle capacity within the wastewater sector: a theoretical justification.

PubMed

Wang, Sheng

2014-04-01

In this work, the values of decentralized (onsite) systems that avoid investments in idle capacity within wastewater plans are quantitatively justified using the specific net present value (SNPV) approach. SNPV is a currently proposed criterion in environmental engineering economics that is defined as the net present value of the cost per unit of service or per population equivalent (PE). The SNPV approach was reintroduced with bugs fixed and then applied to the economic analysis of the capital and operating costs of one-stage completed central plants, stage-expanded central plants, and decentralized treatment facilities. The results show that under a demand growth scenario, the central plant will inevitably reach idle capacity, which can be reduced by a staged expansion. However, the staged expansion plan will lose the economies of scale and, hence, is only viable under projections of a low or moderate price inflation rate or high demand growth rate. Onsite treatment systems can theoretically achieve 100% utilization. Assuming that the capital costs per PE of the onsite and central systems are equal, the former is economically favorable in most cases of price inflation as a result of its cost saving on idle capacity. Onsite treatment systems can be viable even though their capital expenditures per PE are higher than that of a comparable centralized option as to a capital investment. This finding suggests wide opening of onsite technology choices. Use of the SNPV showed that average operating expenses of centralized plants decrease as demand growth rates increase as a benefit of economies of scale, whereas those of onsite treatment systems depend only on price inflation. Semi-decentralized systems feature both the financial advantage of the onsite system (capital investment) and the superiority of centralized systems (operation and maintenance); thus, it is worth consideration. The results of this study illustrate not only the value of decentralized systems but also the value of the SNPV approach in the planning of wastewater services, especially in areas undergoing high demand growth. Copyright © 2014 Elsevier Ltd. All rights reserved.

The path dependence of district manager decision-space in Ghana.

PubMed

Kwamie, Aku; van Dijk, Han; Ansah, Evelyn K; Agyepong, Irene Akua

2016-04-01

The district health system in Ghana today is characterized by high resource-uncertainty and narrow decision-space. This article builds a theory-driven historical case study to describe the influence of path-dependent administrative, fiscal and political decentralization processes on development of the district health system and district manager decision-space. Methods included a non-exhaustive literature review of democratic governance in Ghana, and key informant interviews with high-level health system officials integral to the development of the district health system. Through our analysis we identified four periods of district health system progression: (1) development of the district health system (1970-85); (2) Strengthening District Health Systems Initiative (1986-93); (3) health sector reform planning and creation of the Ghana Health Service (1994-96) and (4) health sector reform implementation (1997-2007). It was observed that district manager decision-space steadily widened during periods (1) and (2), due to increases in managerial profile, and concerted efforts at managerial capacity strengthening. Periods (3) and (4) saw initial augmentation of district health system financing, further widening managerial decision-space. However, the latter half of period 4 witnessed district manager decision-space contraction. Formalization of Ghana Health Service structures influenced by self-reinforcing tendencies towards centralized decision-making, national and donor shifts in health sector financing, and changes in key policy actors all worked to the detriment of the district health system, reversing early gains from bottom-up development of the district health system. Policy feedback mechanisms have been influenced by historical and contemporary sequencing of local government and health sector decentralization. An initial act of administrative decentralization, followed by incomplete political and fiscal decentralization has ensured that the balance of power has remained at national level, with strong vertical accountabilities and dependence of the district on national level. This study demonstrates that the rhetoric of decentralization does not always mirror actual implementation, nor always result in empowered local actors. © The Author 2015. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine.

A new taxonomy for distributed computer systems based upon operating system structure

NASA Technical Reports Server (NTRS)

Foudriat, E. C.

1985-01-01

Characteristics of the resource structure found in the operating system are considered as a mechanism for classifying distributed computer systems. Since the operating system resources, themselves, are too diversified to provide a consistent classification, the structure upon which resources are built and shared are examined. The location and control character of this indivisibility provides the taxonomy for separating uniprocessors, computer networks, network computers (fully distributed processing systems or decentralized computers) and algorithm and/or data control multiprocessors. The taxonomy is important because it divides machines into a classification that is relevant or important to the client and not the hardware architect. It also defines the character of the kernel O/S structure needed for future computer systems. What constitutes an operating system for a fully distributed processor is discussed in detail.

Decentralized adaptive robust control based on sliding mode and nonlinear compensator for the control of ankle movement using functional electrical stimulation of agonist-antagonist muscles

NASA Astrophysics Data System (ADS)

Kobravi, Hamid-Reza; Erfanian, Abbas

2009-08-01

A decentralized control methodology is designed for the control of ankle dorsiflexion and plantarflexion in paraplegic subjects with electrical stimulation of tibialis anterior and calf muscles. Each muscle joint is considered as a subsystem and individual controllers are designed for each subsystem. Each controller operates solely on its associated subsystem, with no exchange of information between the subsystems. The interactions between the subsystems are taken as external disturbances for each isolated subsystem. In order to achieve robustness with respect to external disturbances, unmodeled dynamics, model uncertainty and time-varying properties of muscle-joint dynamics, a robust control framework is proposed which is based on the synergistic combination of an adaptive nonlinear compensator with a sliding mode control and is referred to as an adaptive robust control. Extensive simulations and experiments on healthy and paraplegic subjects were performed to demonstrate the robustness against the time-varying properties of muscle-joint dynamics, day-to-day variations, subject-to-subject variations, fast convergence, stability and tracking accuracy of the proposed method. The results indicate that the decentralized robust control provides excellent tracking control for different reference trajectories and can generate control signals to compensate the muscle fatigue and reject the external disturbance. Moreover, the controller is able to automatically regulate the interaction between agonist and antagonist muscles under different conditions of operating without any preprogrammed antagonist activities.

Decentralized adaptive robust control based on sliding mode and nonlinear compensator for the control of ankle movement using functional electrical stimulation of agonist-antagonist muscles.

PubMed

Kobravi, Hamid-Reza; Erfanian, Abbas

2009-08-01

A decentralized control methodology is designed for the control of ankle dorsiflexion and plantarflexion in paraplegic subjects with electrical stimulation of tibialis anterior and calf muscles. Each muscle joint is considered as a subsystem and individual controllers are designed for each subsystem. Each controller operates solely on its associated subsystem, with no exchange of information between the subsystems. The interactions between the subsystems are taken as external disturbances for each isolated subsystem. In order to achieve robustness with respect to external disturbances, unmodeled dynamics, model uncertainty and time-varying properties of muscle-joint dynamics, a robust control framework is proposed which is based on the synergistic combination of an adaptive nonlinear compensator with a sliding mode control and is referred to as an adaptive robust control. Extensive simulations and experiments on healthy and paraplegic subjects were performed to demonstrate the robustness against the time-varying properties of muscle-joint dynamics, day-to-day variations, subject-to-subject variations, fast convergence, stability and tracking accuracy of the proposed method. The results indicate that the decentralized robust control provides excellent tracking control for different reference trajectories and can generate control signals to compensate the muscle fatigue and reject the external disturbance. Moreover, the controller is able to automatically regulate the interaction between agonist and antagonist muscles under different conditions of operating without any preprogrammed antagonist activities.

Monitoring and control requirement definition study for Dispersed Storage and Generation (DSG). Volume 4, appendix C: Identification from utility visits of present and future approaches to integration of DSG into distribution networks

NASA Technical Reports Server (NTRS)

1980-01-01

Visits to four utilities concerned with the use of DSG power sources on their distribution networks yielded useful impressions of present and future approaches to the integration of DSGs into electrical distribution network. Different approaches to future utility systems with DSG are beginning to take shape. The new DSG sources will be in decentralized locations with some measure of centralized control. The utilities have yet to establish firmly the communication and control means or their organization. For the present, the means for integrating the DSGs and their associated monitoring and control equipment into a unified system have not been decided.

Decentralized care for multidrug-resistant tuberculosis: a systematic review and meta-analysis.

PubMed

Ho, Jennifer; Byrne, Anthony L; Linh, Nguyen N; Jaramillo, Ernesto; Fox, Greg J

2017-08-01

To assess the effectiveness of decentralized treatment and care for patients with multidrug-resistant (MDR) tuberculosis, in comparison with centralized approaches. We searched ClinicalTrials.gov, the Cochrane library, Embase®, Google Scholar, LILACS, PubMed®, Web of Science and the World Health Organization's portal of clinical trials for studies reporting treatment outcomes for decentralized and centralized care of MDR tuberculosis. The primary outcome was treatment success. When possible, we also evaluated, death, loss to follow-up, treatment adherence and health-system costs. To obtain pooled relative risk (RR) estimates, we performed random-effects meta-analyses. Eight studies met the eligibility criteria for review inclusion. Six cohort studies, with 4026 participants in total, reported on treatment outcomes. The pooled RR estimate for decentralized versus centralized care for treatment success was 1.13 (95% CI: 1.01-1.27). The corresponding estimate for loss to follow-up was RR: 0.66 (95% CI: 0.38-1.13), for death RR: 1.01 (95% CI: 0.67-1.52) and for treatment failure was RR: 1.07 (95% CI: 0.48-2.40). Two of three studies evaluating health-care costs reported lower costs for the decentralized models of care than for the centralized models. Treatment success was more likely among patients with MDR tuberculosis treated using a decentralized approach. Further studies are required to explore the effectiveness of decentralized MDR tuberculosis care in a range of different settings.

Decentralized care for multidrug-resistant tuberculosis: a systematic review and meta-analysis

PubMed Central

Byrne, Anthony L; Linh, Nguyen N; Jaramillo, Ernesto; Fox, Greg J

2017-01-01

Abstract Objective To assess the effectiveness of decentralized treatment and care for patients with multidrug-resistant (MDR) tuberculosis, in comparison with centralized approaches. Methods We searched ClinicalTrials.gov, the Cochrane library, Embase®, Google Scholar, LILACS, PubMed®, Web of Science and the World Health Organization’s portal of clinical trials for studies reporting treatment outcomes for decentralized and centralized care of MDR tuberculosis. The primary outcome was treatment success. When possible, we also evaluated, death, loss to follow-up, treatment adherence and health-system costs. To obtain pooled relative risk (RR) estimates, we performed random-effects meta-analyses. Findings Eight studies met the eligibility criteria for review inclusion. Six cohort studies, with 4026 participants in total, reported on treatment outcomes. The pooled RR estimate for decentralized versus centralized care for treatment success was 1.13 (95% CI: 1.01–1.27). The corresponding estimate for loss to follow-up was RR: 0.66 (95% CI: 0.38–1.13), for death RR: 1.01 (95% CI: 0.67–1.52) and for treatment failure was RR: 1.07 (95% CI: 0.48–2.40). Two of three studies evaluating health-care costs reported lower costs for the decentralized models of care than for the centralized models. Conclusion Treatment success was more likely among patients with MDR tuberculosis treated using a decentralized approach. Further studies are required to explore the effectiveness of decentralized MDR tuberculosis care in a range of different settings. PMID:28804170

A QoS Management Technique of Urgent Information Provision in ITS Services Using DSRC for Autonomous Base Stations

NASA Astrophysics Data System (ADS)

Shimura, Akitoshi; Aizono, Takeiki; Hiraiwa, Masashi; Sugano, Shigeki

A QoS management technique based on an autonomous decentralized mobility system, which is an autonomous decentralized system enhanced to provide mobile stations with information about urgent roadway situations, is proposed in this paper. This technique enables urgent messages to be flexibly and quickly transmitted to mobile stations by multiple decentralized base stations using dedicated short range communication. It also supports the easy addition of additional base stations. Each station autonomously creates information-delivery communities based on the urgency of the messages it receives through the roadside network and the distances between the senders and receivers. Each station dynamically determines the urgency of messages according to the message content and the speed of the mobile stations. Evaluation of this technique applied to the Smart Gateway system, which provides driving-assistance services to mobile stations through dedicated short-range communication, demonstrated its effectiveness and that it is suitable for actual systems.

[Filariasis control: entry point for other helminthiasis control programs?].

PubMed

Boussinesq, M

2006-08-01

Filariasis control programs are based on a decentralized drug distribution strategy known as "community-directed". This strategy could also be applied to the control of schistosomiasis and intestinal nematode infections. Integration of these control programs could be highly cost-effective. However, as a prerequisite for integration, it would be necessary to identify zones where these helminthic infections co-exist, specify the population categories that should receive each medication (ivermectin, albendazole, mebendazole, and praziquantel), check that combined administration of these drugs is safe and ensure that an integrated program would have no detrimental effect on the health care system and on the efficacy of ongoing programs.

Decentralized control scheme for myriapod robot inspired by adaptive and resilient centipede locomotion.

PubMed

Yasui, Kotaro; Sakai, Kazuhiko; Kano, Takeshi; Owaki, Dai; Ishiguro, Akio

2017-01-01

Recently, myriapods have attracted the attention of engineers because mobile robots that mimic them potentially have the capability of producing highly stable, adaptive, and resilient behaviors. The major challenge here is to develop a control scheme that can coordinate their numerous legs in real time, and an autonomous decentralized control could be the key to solve this problem. Therefore, we focus on real centipedes and aim to design a decentralized control scheme for myriapod robots by drawing inspiration from behavioral experiments on centipede locomotion under unusual conditions. In the behavioral experiments, we observed the response to the removal of a part of the terrain and to amputation of several legs. Further, we determined that the ground reaction force is significant for generating rhythmic leg movements; the motion of each leg is likely affected by a sensory input from its neighboring legs. Thus, we constructed a two-dimensional model wherein a simple local reflexive mechanism was implemented in each leg. We performed simulations by using this model and demonstrated that the myriapod robot could move adaptively to changes in the environment and body properties. Our findings will shed new light on designing adaptive and resilient myriapod robots that can function under various circumstances.

Cost decomposition of linear systems with application to model reduction

NASA Technical Reports Server (NTRS)

Skelton, R. E.

1980-01-01

A means is provided to assess the value or 'cst' of each component of a large scale system, when the total cost is a quadratic function. Such a 'cost decomposition' of the system has several important uses. When the components represent physical subsystems which can fail, the 'component cost' is useful in failure mode analysis. When the components represent mathematical equations which may be truncated, the 'component cost' becomes a criterion for model truncation. In this latter event component costs provide a mechanism by which the specific control objectives dictate which components should be retained in the model reduction process. This information can be valuable in model reduction and decentralized control problems.

Communication network for decentralized remote tele-science during the Spacelab mission IML-2

NASA Technical Reports Server (NTRS)

Christ, Uwe; Schulz, Klaus-Juergen; Incollingo, Marco

1994-01-01

The ESA communication network for decentralized remote telescience during the Spacelab mission IML-2, called Interconnection Ground Subnetwork (IGS), provided data, voice conferencing, video distribution/conferencing and high rate data services to 5 remote user centers in Europe. The combination of services allowed the experimenters to interact with their experiments as they would normally do from the Payload Operations Control Center (POCC) at MSFC. In addition, to enhance their science results, they were able to make use of reference facilities and computing resources in their home laboratory, which typically are not available in the POCC. Characteristics of the IML-2 communications implementation were the adaptation to the different user needs based on modular service capabilities of IGS and the cost optimization for the connectivity. This was achieved by using a combination of traditional leased lines, satellite based VSAT connectivity and N-ISDN according to the simulation and mission schedule for each remote site. The central management system of IGS allows minimization of staffing and the involvement of communications personnel at the remote sites. The successful operation of IGS for IML-2 as a precursor network for the Columbus Orbital Facility (COF) has proven the concept for communications to support the operation of the COF decentralized scenario.

Cooperative Search by UAV Teams: A Model Predictive Approach Using Dynamic Graphs

DTIC Science & Technology

2011-10-01

decentralized processing and control architecture. SLAMEM asset models accurately represent the Unicorn UAV platforms and other standard military platforms in...IMPLEMENTATION The CGBMPS algorithm has been successfully field-tested using both Unicorn [27] and Raven [20] UAV platforms. This section describes...the hardware-software system setup and implementation used for testing with Unicorns , Toyon’s UAV test platform. We also present some results from the

Centralized Control With Decentralized Execution: Never Divide the Fleet?

DTIC Science & Technology

2003-02-24

goals, priorities, acceptable risks , and limits of the operation.11 In fact, the manual states, “A reluctance to delegate decisions to subordinate...targets, even if that meant dropping a weapon in a crater. The Air Tasking Message ( ATM ) specified loads and standard configurations with little...of shops and supermarkets is distributed. However, market forces drive the supply system; the city manages to feed itself anyway.109 Clearly, the

LEOPACK The integrated services communications system based on LEO satellites

NASA Astrophysics Data System (ADS)

Negoda, A.; Bunin, S.; Bushuev, E.; Dranovsky, V.

LEOPACK is yet another LEO satellite project which provides global integrated services for 'business' communications. It utilizes packet rather then circuit switching in both terrestrial and satellite chains as well as cellular approach for frequencies use. Original multiple access protocols and decentralized network control make it possible to organize regionally or logically independent and world-wide networks. Relatively small number of satellites (28) provides virtually global network coverage.

Finding idle machines in a workstation-based distributed system

NASA Technical Reports Server (NTRS)

Theimer, Marvin M.; Lantz, Keith A.

1989-01-01

The authors describe the design and performance of scheduling facilities for finding idle hosts in a workstation-based distributed system. They focus on the tradeoffs between centralized and decentralized architectures with respect to scalability, fault tolerance, and simplicity of design, as well as several implementation issues of interest when multicast communication is used. They conclude that the principal tradeoff between the two approaches is that a centralized architecture can be scaled to a significantly greater degree and can more easily monitor global system statistics, whereas a decentralized architecture is simpler to implement.

Control Strategies for Distributed Energy Resources to Maximize the Use of Wind Power in Rural Microgrids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Shuai; Elizondo, Marcelo A.; Samaan, Nader A.

2011-10-10

The focus of this paper is to design control strategies for distributed energy resources (DERs) to maximize the use of wind power in a rural microgrid. In such a system, it may be economical to harness wind power to reduce the consumption of fossil fuels for electricity production. In this work, we develop control strategies for DERs, including diesel generators, energy storage and demand response, to achieve high penetration of wind energy in a rural microgrid. Combinations of centralized (direct control) and decentralized (autonomous response) control strategies are investigated. Detailed dynamic models for a rural microgrid are built to conductmore » simulations. The system response to large disturbances and frequency regulation are tested. It is shown that optimal control coordination of DERs can be achieved to maintain system frequency while maximizing wind power usage and reducing the wear and tear on fossil fueled generators.« less

Increased Government Intervention versus Increased Institutional Autonomy: The Recent Case of Australian Higher Education.

ERIC Educational Resources Information Center

Harman, Grant

A new theme in the old tension between centralization and decentralization in the governance and administration of Australian higher education is explored. The argument is that the various major attempts to restructure Australian education systems both in centralizing and decentralizing forces have gained new strength, and that the recent stated…

Study of the Effectiveness of OCR for Decentralized Data Capture and Conversion. Final Report.

ERIC Educational Resources Information Center

Liston, David M.; And Others

The ERIC network conversion to an OCR (Optical Character Recognition) mode of data entry was studied to analyze the potential effectiveness of OCR data entry for future EPC/s (Editorial Processing Centers). Study results are also applicable to any other system involving decentralized bibliographic data capture and conversion functions. The report…

The LEA's Role in a Decentralized School System: The School Principals' View

ERIC Educational Resources Information Center

Addi-Raccah, Audrey; Gavish, Yakov

2010-01-01

Since the wave of school reform decentralization, schools now maintain a more dynamic and diverse relationship with their environment than they did in the past. School principals' relationships with the local educational authority (LEA) are a prominent example of this change in Israel. LEAs try to gain more pedagogic influence over schools while…

Contractual or Responsive Accountability? Neo-Centralist 'Self-Management' or Systemic Subsidiarity? Tasmanian Parents' and Other Stakeholders' Policy Preferences.

ERIC Educational Resources Information Center

Macpherson, R. J. S.

When state governments in Australia decentralized many administrative responsibilities to schools in the late 1980s and early 1990s, it was assumed that they would develop fresh management, development, and governance capacities. In general, such decentralization attempted to replace bureaucracies with corporate management, limit school evaluation…

IRCD Bulletin, Volume 4, Number 5 and Volume 5, Number 1, November 1968-January 1969.

ERIC Educational Resources Information Center

Gordon, Edmund W., Ed.

The articles in this double issue of the "IRCD Bulletin" deal with the proposed decentralization of the New York City school system. Edmund Gordon argues that decentralization can provide the best organizational structure--(1) to make the schools accountable to the parents and communities they serve, (2) to place the responsibility for…

Resilience in social insect infrastructure systems.

PubMed

Middleton, Eliza J T; Latty, Tanya

2016-03-01

Both human and insect societies depend on complex and highly coordinated infrastructure systems, such as communication networks, supply chains and transportation networks. Like human-designed infrastructure systems, those of social insects are regularly subject to disruptions such as natural disasters, blockages or breaks in the transportation network, fluctuations in supply and/or demand, outbreaks of disease and loss of individuals. Unlike human-designed systems, there is no deliberate planning or centralized control system; rather, individual insects make simple decisions based on local information. How do these highly decentralized, leaderless systems deal with disruption? What factors make a social insect system resilient, and which factors lead to its collapse? In this review, we bring together literature on resilience in three key social insect infrastructure systems: transportation networks, supply chains and communication networks. We describe how systems differentially invest in three pathways to resilience: resistance, redirection or reconstruction. We suggest that investment in particular resistance pathways is related to the severity and frequency of disturbance. In the final section, we lay out a prospectus for future research. Human infrastructure networks are rapidly becoming decentralized and interconnected; indeed, more like social insect infrastructures. Human infrastructure management might therefore learn from social insect researchers, who can in turn make use of the mature analytical and simulation tools developed for the study of human infrastructure resilience. © 2016 The Author(s).

Controller design via structural reduced modeling by FETM

NASA Technical Reports Server (NTRS)

Yousuff, A.

1986-01-01

The Finite Element - Transfer Matrix (FETM) method has been developed to reduce the computations involved in analysis of structures. This widely accepted method, however, has certain limitations, and does not directly produce reduced models for control design. To overcome these shortcomings, a modification of FETM method has been developed. The modified FETM method easily produces reduced models that are tailored toward subsequent control design. Other features of this method are its ability to: (1) extract open loop frequencies and mode shapes with less computations, (2) overcome limitations of the original FETM method, and (3) simplify the procedures for output feedback, constrained compensation, and decentralized control. This semi annual report presents the development of the modified FETM, and through an example, illustrates its applicability to an output feedback and a decentralized control design.

The experience of implementing the board of trustees’ policy in teaching hospitals in Iran: an example of health system decentralization

PubMed Central

Doshmangir, Leila; Rashidian, Arash; Ravaghi, Hamid; Takian, Amirhossein; Jafari, Mehdi

2015-01-01

Background: In 2004, the health system in Iran initiated an organizational reform aiming to increase the autonomy of teaching hospitals and make them more decentralized. The policy led to the formation of a board of trustees in each hospital and significant modifications in hospitals’ financing. Since the reform aimed to improve its predecessor policy (implementation of hospital autonomy began in 1995), it expected to increase user satisfaction, as well as enhance effectiveness and efficiency of healthcare services in targeted hospitals. However, such expectations were never realized. In this research, we explored the perceptions and views of expert stakeholders as to why the board of trustees’ policy did not achieve its perceived objectives. Methods: We conducted 47 semi-structured face-to-face interviews and two focus group discussions (involving 8 and 10 participants, respectively) with experts at high, middle, and low levels of Iran’s health system, using purposive and snowball sampling. We also collected a comprehensive set of relevant documents. Interviews were transcribed verbatim and analyzed thematically, following a mixed inductive-deductive approach. Results: Three main themes emerged from the analysis. The implementation approach (including the processes, views about the policy and the links between the policy components), using research evidence about the policy (local and global), and policy context (health system structure, health insurers capacity, hospitals’ organization and capacity and actors’ interrelationships) affected the policy outcomes. Overall, the implementation of hospital decentralization policies in Iran did not seem to achieve their intended targets as a result of assumed failure to take full consideration of the above factors in policy implementation into account. Conclusion: The implementation of the board of trustees’ policy did not achieve its desired goals in teaching hospitals in Iran. Similar decentralization policies in the past and their outcomes were overlooked, while the context was not prepared appropriately and key stakeholders, particularly the government, did not support the decentralization of Iran’s health system. PMID:25844379

Network-Cognizant Design of Decentralized Volt/VAR Controllers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Kyri A; Bernstein, Andrey; Zhao, Changhong

This paper considers the problem of designing decentralized Volt/VAR controllers for distributed energy resources (DERs). The voltage-reactive power characteristics of individual DERs are obtained by solving a convex optimization problem, where given performance objectives (e.g., minimization of the voltage deviations from a given profile) are specified and stability constraints are enforced. The resultant Volt/VAR characteristics are network-cognizant, in the sense that they embed information on the location of the DERs and, consequently, on the effect of reactive-power adjustments on the voltages throughout the feeder. Bounds on the maximum voltage deviation incurred by the controllers are analytically established. Numerical results aremore » reported to corroborate the technical findings.« less

Economic considerations for social distancing and behavioral based policies during an epidemic

PubMed Central

Fenichel, Eli P.

2013-01-01

Public policies intended to induce behavioral change, specifically incentives to reduce interpersonal contacts or to “social distance,” increasingly play a prominent role in public disease response strategies as governments plan for and respond to major epidemics. I compare social distancing incentives and outcomes under decentralized, full control social planner, and constrained social planner, without health class specific control, decision making scenarios. Constrained social planner decision making, based on non-health class specific controls, can in some instances make society worse off than decentralized decision making (i.e. no intervention). The oft neglected behavior of recovered and immune individuals is important for welfare and health outcomes. PMID:23419635

Model-Based Design of Tree WSNs for Decentralized Detection.

PubMed

Tantawy, Ashraf; Koutsoukos, Xenofon; Biswas, Gautam

2015-08-20

The classical decentralized detection problem of finding the optimal decision rules at the sensor and fusion center, as well as variants that introduce physical channel impairments have been studied extensively in the literature. The deployment of WSNs in decentralized detection applications brings new challenges to the field. Protocols for different communication layers have to be co-designed to optimize the detection performance. In this paper, we consider the communication network design problem for a tree WSN. We pursue a system-level approach where a complete model for the system is developed that captures the interactions between different layers, as well as different sensor quality measures. For network optimization, we propose a hierarchical optimization algorithm that lends itself to the tree structure, requiring only local network information. The proposed design approach shows superior performance over several contentionless and contention-based network design approaches.

Energy-efficient pulse-coupled synchronization strategy design for wireless sensor networks through reduced idle listening

PubMed Central

Wang, Yongqiang; Núñez, Felipe; Doyle, Francis J.

2013-01-01

Synchronization is crucial to wireless sensor networks due to their decentralized structure. We propose an energy-efficient pulse-coupled synchronization strategy to achieve this goal. The basic idea is to reduce idle listening by intentionally introducing a large refractory period in the sensors’ cooperation. The large refractory period greatly reduces idle listening in each oscillation period, and is analytically proven to have no influence on the time to synchronization. Hence, it significantly reduces the total energy consumption in a synchronization process. A topology control approach tailored for pulse-coupled synchronization is given to guarantee a k-edge strongly connected interaction topology, which is tolerant to communication-link failures. The topology control approach is totally decentralized and needs no information exchange among sensors, and it is applicable to dynamic network topologies as well. This facilitates a completely decentralized implementation of the synchronization strategy. The strategy is applicable to mobile sensor networks, too. QualNet case studies confirm the effectiveness of the synchronization strategy. PMID:24307831

Study on an integrated process combining ozonation with ceramic ultra-filtration for decentralized supply of drinking water.

PubMed

Zhu, Jia; Fan, Xiao J; Tao, Yi; Wei, De Q; Zhang, Xi H

2014-09-19

An integrated process was specifically developed for the decentralized supply of drinking water from micro-polluted surface water in the rural areas of China. The treatment process combined ozonation with ceramic ultra-filtration (UF), coagulation for pre-treatment and granular activated carbon filtration. A flat-sheet ceramic membrane was used with a cut-off of 60 nm and the measurement of 254 mm (length) × 240 mm (width) × 6 mm (thickness). Ozonation and ceramic UF was set up whthin one reactor. The experimental results showed that the removal efficiencies of the dissolved organic carbon (DOC) and the formation potential of trihalomethanes (THMs), haloacetic acids (HAAs) and ammonia were 80%, 76%, 70% and 90%, respectively; that the turbidity of the product water was below 0.2 NTU and the particle count number (particles larger than 2 μm) was less than 50 counts per mL. The result also showed that all the pathogenic microorganisms were retained by the ceramic and that UF. Ozonation played a critical role in the control of membrane fouling and the removal of contaminants. Exactly, the membrane fouling can be controlled in situ with 3 mg L(-1) ozone at the permeate flux of 80 L m(-2) h(-1), yet the required dosage of ozone was dependent on the quality of the raw water. Therefore, this study is able to provide a highly compacted system for decentralized supply of high-quality drinking water in terms of both chemical and microbiological safety for the rural areas in China.

The economics of central billing offices.

PubMed

Woodcock, E; Nguyen, L

2000-01-01

The anticipation of economies of scale in physician billing has led many medical practices to consolidate their billing operations. This article analyzes these economies of scale, comparing performance indicators from centralized and decentralized operations. While consolidation provides compliance, control and information, diseconomies of scale can exist in the centralized receivables management process. The authors conclude that physician practices should consider a hybrid approach to billing, thus reaping the benefits of both centralization and decentralization.

A cylindrical SPECT camera with de-centralized readout scheme

NASA Astrophysics Data System (ADS)

Habte, F.; Stenström, P.; Rillbert, A.; Bousselham, A.; Bohm, C.; Larsson, S. A.

2001-09-01

An optimized brain single photon emission computed tomograph (SPECT) camera is being designed at Stockholm University and Karolinska Hospital. The design goal is to achieve high sensitivity, high-count rate and high spatial resolution. The sensitivity is achieved by using a cylindrical crystal, which gives a closed geometry with large solid angles. A de-centralized readout scheme where only a local environment around the light excitation is readout supports high-count rates. The high resolution is achieved by using an optimized crystal configuration. A 12 mm crystal plus 12 mm light guide combination gave an intrinsic spatial resolution better than 3.5 mm (140 keV) in a prototype system. Simulations show that a modified configuration can improve this value. A cylindrical configuration with a rotating collimator significantly simplifies the mechanical design of the gantry. The data acquisition and control system uses early digitization and subsequent digital signal processing to extract timing and amplitude information, and monitors the position of the collimator. The readout system consists of 12 or more modules each based on programmable logic and a digital signal processor. The modules send data to a PC file server-reconstruction engine via a Firewire (IEEE-1394) network.

Trends in modern system theory

NASA Technical Reports Server (NTRS)

Athans, M.

1976-01-01

The topics considered are related to linear control system design, adaptive control, failure detection, control under failure, system reliability, and large-scale systems and decentralized control. It is pointed out that the design of a linear feedback control system which regulates a process about a desirable set point or steady-state condition in the presence of disturbances is a very important problem. The linearized dynamics of the process are used for design purposes. The typical linear-quadratic design involving the solution of the optimal control problem of a linear time-invariant system with respect to a quadratic performance criterion is considered along with gain reduction theorems and the multivariable phase margin theorem. The stumbling block in many adaptive design methodologies is associated with the amount of real time computation which is necessary. Attention is also given to the desperate need to develop good theories for large-scale systems, the beginning of a microprocessor revolution, the translation of the Wiener-Hopf theory into the time domain, and advances made in dynamic team theory, dynamic stochastic games, and finite memory stochastic control.

Are reproductive health NGOs in Uganda able to engage in the health SWAp?

PubMed

Mugisha, Frank; Birungi, Harriet; Askew, Ian

2005-01-01

This paper explores the ability for reproductive health (RH) non-governmental organizations (NGO) in Uganda to survive in the context of SWAp and decentralization. The authors argue that, contrary to the perceptions that this context may increase NGO's financial vulnerability, a SWAp and a decentralized system may provide an opportunity that should be embraced by NGOs to enhance their sustainability and effectiveness by reducing their current dependency on donor funding. The paper discusses the systemic weaknesses of many NGOs that currently make them vulnerable, and observes that unless these weaknesses are addressed, such NGOs will lose their space in the SWAp and decentralization arena. The authors suggest that NGOs need to recognize the opportunities that participating in public-private partnerships through a SWAp can offer them for long-term and significant funding. They need also to develop their capacity to pro-actively participate in a SWAp and decentralized context by becoming more entrepreneurial in nature, through re-orienting their organizational philosophies and strategic planning and budgeting so as to be able to partner effectively with the public sector in accessing funds made available through health sector reform.

Anterior capsule contraction and intraocular lens decentration and tilt after hydrogel lens implantation

PubMed Central

Hayashi, K.; Hayashi, H.; Nakao, F.; Hayashi, F.

2001-01-01

AIM—To prospectively investigate changes in the area of the anterior capsule opening, and intraocular lens (IOL) decentration and tilt after implantation of a hydrogel IOL.
METHODS—100 patients underwent implantation of a hydrogel IOL in one eye and an acrylic IOL implantation in the opposite eye. The area of the anterior capsule opening, and the degree of IOL decentration and tilt were measured using the Scheimpflug videophotography system at 3 days, and at 1, 3, and 6 months postoperatively.
RESULTS—The mean anterior capsule opening area decreased significantly in both groups. At 6 months postoperatively, the area in the hydrogel group was significantly smaller than that in the acrylic group. The mean percentage of the area reduction in the hydrogel group was also significantly greater than that in the acrylic group, being 16.9% in the hydrogel group and 8.8% in the acrylic group. In contrast, IOL decentration and tilt did not progress in either group. No significant differences were found in the degree of IOL decentration and tilt throughout the follow up period.
CONCLUSIONS—Contraction of the anterior capsule opening was more extensive with the hydrogel IOL than with the acrylic IOL, but the degree of IOL decentration and tilt were similar for the two types of lenses studied.

 PMID:11673291

Bibliographic Control in South Africa

ERIC Educational Resources Information Center

Musiker, Reuben

1972-01-01

The author sets as his task the consideration of the present state of bibliographical control of South Africa's bookstock with special reference to centralization and decentralization. (20 references) (Author/SJ)

Federalism and decentralization: impact on international and Brazilian health policies.

PubMed

Leite, Valéria Rodrigues; de Vasconcelos, Cipriano Maia; Lima, Kenio Costa

2011-01-01

This article discusses the implications of decentralization in the light of international and Brazilian federalism, and its effects on public health policy. In a comparative analysis among countries, the authors find there is no single model; rather, each country has a unique structure of institutions and norms that have important implications for the operation of its health system. Brazil shares some similarities with other countries that have adopted a decentralized system and is assuming features ever closer to U.S. federalism, with a complex web of relationships. The degree of inequality among Brazilian municipalities and states, along with the budgetary imbalances caused by the minimal levels of resource utilization, undermines Brazil's constitutional principles and, consequently, its federalism. To ensure the constitutional mandate in Brazil, it is essential, as in other countries, to create a stable source of funds and increase the volume and efficiency of spending. Also important are investing in the training of managers, improving information systems, strengthening the principles of autonomy and interdependence, and defining patterns of cooperation within the federation.

Non-Discretionary Access Control for Decentralized Computing Systems

DTIC Science & Technology

1977-05-01

Semaphores are inherently read-write objects to all users. Reed and Kanodia <Reed77> propose a scheme for process synchronization using...Capabilities 84 8.2.4.4 UNIX Style Naming 85 8.2.5 Garbage Collection 86 8.3 Synchronization Without Writing 87 9. Downgrading Information 89 9.1...intruder could not follow the rapid exchange of messages and would be unable to extract information. Farber and Larsen describe synchronization and

Time-Coordination Strategies and Control Laws for Multi-Agent Unmanned Systems

NASA Technical Reports Server (NTRS)

Puig-Navarro, Javier; Hovakimyan, Naira; Allen, B. Danette

2017-01-01

Time-critical coordination tools for unmanned systems can be employed to enforce the type of temporal constraints required in terminal control areas, ensure minimum distance requirements among vehicles are satisfied, and successfully perform coordinated missions. In comparison with previous literature, this paper presents an ampler spectrum of coordination and temporal specifications for unmanned systems, and proposes a general control law that can enforce this range of constraints. The constraint classification presented con- siders the nature of the desired arrival window and the permissible coordination errors to define six different types of time-coordination strategies. The resulting decentralized coordination control law allows the vehicles to negotiate their speeds along their paths in response to information exchanged over the communication network. This control law organizes the different members in the fleet hierarchically per their behavior and informational needs as reference agent, leaders, and followers. Examples and simulation results for all the coordination strategies presented demonstrate the applicability and efficacy of the coordination control law for multiple unmanned systems.

Experimental robot gripper control for handling of soft objects

NASA Astrophysics Data System (ADS)

Friedrich, Werner E.; Ziegler, T. H.; Lim, P.

1996-10-01

The challenging task of automated handling of variable objects necessitates a combination of innovative engineering and advanced information technology. This paper describes the application of a recently developed control strategy applied to overcome some limitations of robot handling, particularly when dealing with variable objects. The paper focuses on a novel approach to accommodate the need for sensing and actuation in controlling the pickup procedure. An experimental robot-based system for the handling of soft parts, ranging from artificial components to natural objects such as fruit and meat pieces was developed. The configuration comprises a modular gripper subsystem, and an industrial robot as part of a distributed control system. The gripper subsystem features manually configurable fingers with integrated sensing capabilities. The control architecture is based on a concept of decentralized control differentiating between positioning and gripping procedures. In this way, the robot and gripper systems are treated as individual handling operations. THis concept allows very short set-up times for future changes involving one or more sub-systems.

A High-Authority/Low-Authority Control Strategy for Coupled Aircraft-Style Bays

NASA Technical Reports Server (NTRS)

Schiller, N. H.; Fuller, C. R.; Cabell, R. H.

2006-01-01

This paper presents a numerical investigation of an active structural acoustic control strategy for coupled aircraft-style bays. While structural coupling can destabilize or limit the performance of some model-based decentralized control systems, fullycoupled centralized control strategies are impractical for typical aircraft containing several hundred bays. An alternative is to use classical rate feedback with matched, collocated transducer pairs to achieve active damping. Unfortunately, due to the conservative nature of this strategy, stability is guaranteed at the expense of achievable noise reduction. Therefore, this paper describes the development of a combined control strategy using robust active damping in addition to a high-authority controller based on linear quadratic Gaussian (LQG) theory. The combined control system is evaluated on a tensioned, two-bay model using piezoceramic actuators and ideal point velocity sensors. Transducer placement on the two-bay structure is discussed, and the advantages of a combined control strategy are presented.

Control allocation for gimballed/fixed thrusters

NASA Astrophysics Data System (ADS)

Servidia, Pablo A.

2010-02-01

Some overactuated control systems use a control distribution law between the controller and the set of actuators, usually called control allocator. Beyond the control allocator, the configuration of actuators may be designed to be able to operate after a single point of failure, for system optimization and/or decentralization objectives. For some type of actuators, a control allocation is used even without redundancy, being a good example the design and operation of thruster configurations. In fact, as the thruster mass flow direction and magnitude only can be changed under certain limits, this must be considered in the feedback implementation. In this work, the thruster configuration design is considered in the fixed (F), single-gimbal (SG) and double-gimbal (DG) thruster cases. The minimum number of thrusters for each case is obtained and for the resulting configurations a specific control allocation is proposed using a nonlinear programming algorithm, under nominal and single-point of failure conditions.

[The impact of non-thrombolytic management of acute ischemic stroke in older individuals: the experience of the Federal District, Brazil].

PubMed

Moura, Mirian; Casulari, Luiz Augusto

2015-07-01

To analyze the impact of a non-specific, decentralized treatment protocol for ischemic stroke in older individuals on the quality of the care provided in the public health care system (SUS, Sistema Único de Saúde) in the Federal District. This retrospective historical control study employed data from the SUS Hospital Information System (SIH/SUS). Two time periods were compared: before and after the adoption of a protocol based on non-specific measures (medical therapy without alteplase) and decentralized care. A set of 2 369 admissions of patients older than 60 years with ischemic stroke was analyzed for the period of 2006/2007, and 5 207 admissions for 2010/2011. The variables were frequency, length of stay, mortality, lethality of ischemic stroke, intensive care unit (ICU) admission, and hospital reimbursement for ischemic stroke admissions. Effectiveness was evaluated based on mortality and lethality rates and efficiency was evaluated based on length of stay, use of ICU, and reimbursed amounts. In the second time period, there was an increase of 119.8% in the number of ischemic stroke admissions (P = 0.0001), increase of 27.3% in absolute mortality, decrease of 5.0% in lethality rate (P = 0.02), and increase of 130.6% in ICU utilization rate (P = 0.0001). There was no difference between the periods regarding mean number of inpatient days and reimbursed amounts. The indicators used in the present study showed improved effectiveness of acute ischemic stroke treatment with the use of a non-specific, decentralized protocol. However, no impact was observed on efficiency.

The impact of South Africa's new constitution on the organization of health services in the post-apartheid era.

PubMed

Pillay, Y

2001-08-01

This essay evaluates the transformation of the health care system in South Africa in the five years following the end of apartheid. This period has witnessed dramatic and wide-ranging changes in the roles of the central and provincial governments as well as many of the same problems related to decentralization as have been seen elsewhere in the world. The importance of effective intergovernmental relations to the creation of a national health system is highlighted. Negotiation. contracting, and coordination skills and mechanisms need to be strengthened to ensure a more effective national health system within a decentralized political system.

A Low Cost Concept for Data Acquisition Systems Applied to Decentralized Renewable Energy Plants

PubMed Central

Jucá, Sandro C. S.; Carvalho, Paulo C. M.; Brito, Fábio T.

2011-01-01

The present paper describes experiences of the use of monitoring and data acquisition systems (DAS) and proposes a new concept of a low cost DAS applied to decentralized renewable energy (RE) plants with an USB interface. The use of such systems contributes to disseminate these plants, recognizing in real time local energy resources, monitoring energy conversion efficiency and sending information concerning failures. These aspects are important, mainly for developing countries, where decentralized power plants based on renewable sources are in some cases the best option for supplying electricity to rural areas. Nevertheless, the cost of commercial DAS is still a barrier for a greater dissemination of such systems in developing countries. The proposed USB based DAS presents a new dual clock operation philosophy, in which the acquisition system contains two clock sources for parallel information processing from different communication protocols. To ensure the low cost of the DAS and to promote the dissemination of this technology in developing countries, the proposed data acquisition firmware and the software for USB microcontrollers programming is a free and open source software, executable in the Linux and Windows® operating systems. PMID:22346600

A low cost concept for data acquisition systems applied to decentralized renewable energy plants.

PubMed

Jucá, Sandro C S; Carvalho, Paulo C M; Brito, Fábio T

2011-01-01

The present paper describes experiences of the use of monitoring and data acquisition systems (DAS) and proposes a new concept of a low cost DAS applied to decentralized renewable energy (RE) plants with an USB interface. The use of such systems contributes to disseminate these plants, recognizing in real time local energy resources, monitoring energy conversion efficiency and sending information concerning failures. These aspects are important, mainly for developing countries, where decentralized power plants based on renewable sources are in some cases the best option for supplying electricity to rural areas. Nevertheless, the cost of commercial DAS is still a barrier for a greater dissemination of such systems in developing countries. The proposed USB based DAS presents a new dual clock operation philosophy, in which the acquisition system contains two clock sources for parallel information processing from different communication protocols. To ensure the low cost of the DAS and to promote the dissemination of this technology in developing countries, the proposed data acquisition firmware and the software for USB microcontrollers programming is a free and open source software, executable in the Linux and Windows® operating systems.

A decentralized linear quadratic control design method for flexible structures

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Craig, Roy R., Jr.

1990-01-01

A decentralized suboptimal linear quadratic control design procedure which combines substructural synthesis, model reduction, decentralized control design, subcontroller synthesis, and controller reduction is proposed for the design of reduced-order controllers for flexible structures. The procedure starts with a definition of the continuum structure to be controlled. An evaluation model of finite dimension is obtained by the finite element method. Then, the finite element model is decomposed into several substructures by using a natural decomposition called substructuring decomposition. Each substructure, at this point, still has too large a dimension and must be reduced to a size that is Riccati-solvable. Model reduction of each substructure can be performed by using any existing model reduction method, e.g., modal truncation, balanced reduction, Krylov model reduction, or mixed-mode method. Then, based on the reduced substructure model, a subcontroller is designed by an LQ optimal control method for each substructure independently. After all subcontrollers are designed, a controller synthesis method called substructural controller synthesis is employed to synthesize all subcontrollers into a global controller. The assembling scheme used is the same as that employed for the structure matrices. Finally, a controller reduction scheme, called the equivalent impulse response energy controller (EIREC) reduction algorithm, is used to reduce the global controller to a reasonable size for implementation. The EIREC reduced controller preserves the impulse response energy of the full-order controller and has the property of matching low-frequency moments and low-frequency power moments. An advantage of the substructural controller synthesis method is that it relieves the computational burden associated with dimensionality. Besides that, the SCS design scheme is also a highly adaptable controller synthesis method for structures with varying configuration, or varying mass and stiffness properties.

Model-Based Design of Tree WSNs for Decentralized Detection †

PubMed Central

Tantawy, Ashraf; Koutsoukos, Xenofon; Biswas, Gautam

2015-01-01

The classical decentralized detection problem of finding the optimal decision rules at the sensor and fusion center, as well as variants that introduce physical channel impairments have been studied extensively in the literature. The deployment of WSNs in decentralized detection applications brings new challenges to the field. Protocols for different communication layers have to be co-designed to optimize the detection performance. In this paper, we consider the communication network design problem for a tree WSN. We pursue a system-level approach where a complete model for the system is developed that captures the interactions between different layers, as well as different sensor quality measures. For network optimization, we propose a hierarchical optimization algorithm that lends itself to the tree structure, requiring only local network information. The proposed design approach shows superior performance over several contentionless and contention-based network design approaches. PMID:26307989

Spillover stabilization and decentralized modal control of large space structures

NASA Technical Reports Server (NTRS)

Czajkowski, Eva A.; Preumont, Andre

1987-01-01

The stabilization of the neglected dynamics of the higher modes of vibration in large space structures is studied, and the influence of the structure of the plant noise intensity matrix of the Kalman-Bucy filter on the stability margin of the residual modes is shown. An optimization procedure uses information on the residual modes to minimize spillover of known residual modes while preserving robustness with respect to the unknown dynamics, and the optimum plant noise intensity matrix is selected to maximize the stability margins of the residual modes and to properly place the observer poles. Examples for both centralized and decentralized control are considered.

Asynchronous, Decentralized DS-CDMA Using Feedback-Controlled Spreading Sequences for Time-Dispersive Channels

NASA Astrophysics Data System (ADS)

Miyatake, Teruhiko; Chiba, Kazuki; Hamamura, Masanori; Tachikawa, Shin'ichi

We propose a novel asynchronous direct-sequence codedivision multiple access (DS-CDMA) using feedback-controlled spreading sequences (FCSSs) (FCSS/DS-CDMA). At the receiver of FCSS/DS-CDMA, the code-orthogonalizing filter (COF) produces a spreading sequence, and the receiver returns the spreading sequence to the transmitter. Then the transmitter uses the spreading sequence as its updated version. The performance of FCSS/DS-CDMA is evaluated over time-dispersive channels. The results indicate that FCSS/DS-CDMA greatly suppresses both the intersymbol interference (ISI) and multiple access interference (MAI) over time-invariant channels. FCSS/DS-CDMA is applicable to the decentralized multiple access.

Decentralized safety concept for closed-loop controlled intensive care.

PubMed

Kühn, Jan; Brendle, Christian; Stollenwerk, André; Schweigler, Martin; Kowalewski, Stefan; Janisch, Thorsten; Rossaint, Rolf; Leonhardt, Steffen; Walter, Marian; Kopp, Rüdger

2017-04-01

This paper presents a decentralized safety concept for networked intensive care setups, for which a decentralized network of sensors and actuators is realized by embedded microcontroller nodes. It is evaluated for up to eleven medical devices in a setup for automated acute respiratory distress syndrome (ARDS) therapy. In this contribution we highlight a blood pump supervision as exemplary safety measure, which allows a reliable bubble detection in an extracorporeal blood circulation. The approach is validated with data of animal experiments including 35 bubbles with a size between 0.05 and 0.3 ml. All 18 bubbles with a size down to 0.15 ml are successfully detected. By using hidden Markov models (HMMs) as statistical method the number of necessary sensors can be reduced by two pressure sensors.

Facility Monitoring: A Qualitative Theory for Sensor Fusion

NASA Technical Reports Server (NTRS)

Figueroa, Fernando

2001-01-01

Data fusion and sensor management approaches have largely been implemented with centralized and hierarchical architectures. Numerical and statistical methods are the most common data fusion methods found in these systems. Given the proliferation and low cost of processing power, there is now an emphasis on designing distributed and decentralized systems. These systems use analytical/quantitative techniques or qualitative reasoning methods for date fusion.Based on other work by the author, a sensor may be treated as a highly autonomous (decentralized) unit. Each highly autonomous sensor (HAS) is capable of extracting qualitative behaviours from its data. For example, it detects spikes, disturbances, noise levels, off-limit excursions, step changes, drift, and other typical measured trends. In this context, this paper describes a distributed sensor fusion paradigm and theory where each sensor in the system is a HAS. Hence, given the reach qualitative information from each HAS, a paradigm and formal definitions are given so that sensors and processes can reason and make decisions at the qualitative level. This approach to sensor fusion makes it possible the implementation of intuitive (effective) methods to monitor, diagnose, and compensate processes/systems and their sensors. This paradigm facilitates a balanced distribution of intelligence (code and/or hardware) to the sensor level, the process/system level, and a higher controller level. The primary application of interest is in intelligent health management of rocket engine test stands.

Human resources for health and decentralization policy in the Brazilian health system

PubMed Central

2011-01-01

Background The Brazilian health reform process, following the establishment of the Unified Health System (SUS), has had a strong emphasis on decentralization, with a special focus on financing, management and inter-managerial agreements. Brazil is a federal country and the Ministry of Health (MoH), through the Secretary of Labour Management and Health Education, is responsible for establishing national policy guidelines for health labour management, and also for implementing strategies for the decentralization of management of labour and education in the federal states. This paper assesses whether the process of decentralizing human resources for health (HRH) management and organization to the level of the state and municipal health departments has involved investments in technical, political and financial resources at the national level. Methods The research methods used comprise a survey of HRH managers of states and major municipalities (including capitals) and focus groups with these HRH managers - all by geographic region. The results were obtained by combining survey and focus group data, and also through triangulation with the results of previous research. Results The results of this evaluation showed the evolution policy, previously restricted to the field of 'personnel administration', now expanded to a conceptual model for health labour management and education-- identifying progress, setbacks, critical issues and challenges for the consolidation of the decentralized model for HRH management. The results showed that 76.3% of the health departments have an HRH unit. It was observed that 63.2% have an HRH information system. However, in most health departments, the HRH unit uses only the payroll and administrative records as data sources. Concerning education in health, 67.6% of the HRH managers mentioned existing cooperation with educational and teaching institutions for training and/or specialization of health workers. Among them, specialization courses account for 61.4% and short courses for 56.1%. Conclusions Due to decentralization, the HRH area has been restructured and policies beyond traditional administrative activities have been developed. However, twenty years on from the establishment of the SUS, there remains a low level of institutionalization in the HRH area, despite recent efforts of the MoH. PMID:21586156

Human resources for health and decentralization policy in the Brazilian health system.

PubMed

Pierantoni, Celia Regina; Garcia, Ana Claudia P

2011-05-17

The Brazilian health reform process, following the establishment of the Unified Health System (SUS), has had a strong emphasis on decentralization, with a special focus on financing, management and inter-managerial agreements. Brazil is a federal country and the Ministry of Health (MoH), through the Secretary of Labour Management and Health Education, is responsible for establishing national policy guidelines for health labour management, and also for implementing strategies for the decentralization of management of labour and education in the federal states. This paper assesses whether the process of decentralizing human resources for health (HRH) management and organization to the level of the state and municipal health departments has involved investments in technical, political and financial resources at the national level. The research methods used comprise a survey of HRH managers of states and major municipalities (including capitals) and focus groups with these HRH managers - all by geographic region. The results were obtained by combining survey and focus group data, and also through triangulation with the results of previous research. The results of this evaluation showed the evolution policy, previously restricted to the field of 'personnel administration', now expanded to a conceptual model for health labour management and education-- identifying progress, setbacks, critical issues and challenges for the consolidation of the decentralized model for HRH management. The results showed that 76.3% of the health departments have an HRH unit. It was observed that 63.2% have an HRH information system. However, in most health departments, the HRH unit uses only the payroll and administrative records as data sources. Concerning education in health, 67.6% of the HRH managers mentioned existing cooperation with educational and teaching institutions for training and/or specialization of health workers. Among them, specialization courses account for 61.4% and short courses for 56.1%. Due to decentralization, the HRH area has been restructured and policies beyond traditional administrative activities have been developed. However, twenty years on from the establishment of the SUS, there remains a low level of institutionalization in the HRH area, despite recent efforts of the MoH.

The need for the use of XACML access control policy in a distributed EHR and some performance considerations.

PubMed

Sucurovic, Snezana; Milutinovic, Veljko

2008-01-01

The Internet based distributed large scale information systems implements attribute based access control (ABAC) rather than Role Based Access Control (RBAC). The reason is that the Internet is identity less and that ABAC scales better. EXtensible Access Control Markup Language is standardized language for writing access control policies, access control requests and access control responses in ABAC. XACML can provide decentralized administration and credentials distribution. In year 2002 version of CEN ENV 13 606 attributes have been attached to EHCR components and in such a system ABAC and XACML have been easy to implement. This paper presents writing XACML policies in the case when attributes are in hierarchical structure. It is presented two possible solutions to write XACML policy in that case and that the solution when set functions are used is more compact and provides 10% better performances.

Integration of Decentralized Thermal Storages Within District Heating (DH) Networks

NASA Astrophysics Data System (ADS)

Schuchardt, Georg K.

2016-12-01

Thermal Storages and Thermal Accumulators are an important component within District Heating (DH) systems, adding flexibility and offering additional business opportunities for these systems. Furthermore, these components have a major impact on the energy and exergy efficiency as well as the heat losses of the heat distribution system. Especially the integration of Thermal Storages within ill-conditioned parts of the overall DH system enhances the efficiency of the heat distribution. Regarding an illustrative and simplified example for a DH system, the interactions of different heat storage concepts (centralized and decentralized) and the heat losses, energy and exergy efficiencies will be examined by considering the thermal state of the heat distribution network.

Adaptive independent joint control of manipulators - Theory and experiment

NASA Technical Reports Server (NTRS)

Seraji, H.

1988-01-01

The author presents a simple decentralized adaptive control scheme for multijoint robot manipulators based on the independent joint control concept. The proposed control scheme for each joint consists of a PID (proportional integral and differential) feedback controller and a position-velocity-acceleration feedforward controller, both with adjustable gains. The static and dynamic couplings that exist between the joint motions are compensated by the adaptive independent joint controllers while ensuring trajectory tracking. The proposed scheme is implemented on a MicroVAX II computer for motion control of the first three joints of a PUMA 560 arm. Experimental results are presented to demonstrate that trajectory tracking is achieved despite strongly coupled, highly nonlinear joint dynamics. The results confirm that the proposed decentralized adaptive control of manipulators is feasible, in spite of strong interactions between joint motions. The control scheme presented is computationally very fast and is amenable to parallel processing implementation within a distributed computing architecture, where each joint is controlled independently by a simple algorithm on a dedicated microprocessor.

Wave field synthesis, adaptive wave field synthesis and ambisonics using decentralized transformed control: Potential applications to sound field reproduction and active noise control

NASA Astrophysics Data System (ADS)

Gauthier, Philippe-Aubert; Berry, Alain; Woszczyk, Wieslaw

2005-09-01

Sound field reproduction finds applications in listening to prerecorded music or in synthesizing virtual acoustics. The objective is to recreate a sound field in a listening environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. Classical WFS, therefore, does not perform well in a real reproduction space such as room. Previous work has suggested that it is physically possible to reproduce a progressive wave field in-room situation using active control approaches. In this paper, a formulation of adaptive wave field synthesis (AWFS) introduces practical possibilities for an adaptive sound field reproduction combining WFS and active control (with WFS departure penalization) with a limited number of error sensors. AWFS includes WFS and closed-loop ``Ambisonics'' as limiting cases. This leads to the modification of the multichannel filtered-reference least-mean-square (FXLMS) and the filtered-error LMS (FELMS) adaptive algorithms for AWFS. Decentralization of AWFS for sound field reproduction is introduced on the basis of sources' and sensors' radiation modes. Such decoupling may lead to decentralized control of source strength distributions and may reduce computational burden of the FXLMS and the FELMS algorithms used for AWFS. [Work funded by NSERC, NATEQ, Université de Sherbrooke and VRQ.] Ultrasound/Bioresponse to

Analysis of airframe/engine interactions - An integrated control perspective

NASA Technical Reports Server (NTRS)

Schmidt, David K.; Schierman, John D.; Garg, Sanjay

1990-01-01

Techniques for the analysis of the dynamic interactions between airframe/engine dynamical systems are presented. Critical coupling terms are developed that determine the significance of these interactions with regard to the closed loop stability and performance of the feedback systems. A conceptual model is first used to indicate the potential sources of the coupling, how the coupling manifests itself, and how the magnitudes of these critical coupling terms are used to quantify the effects of the airframe/engine interactions. A case study is also presented involving an unstable airframe with thrust vectoring for attitude control. It is shown for this system with classical, decentralized control laws that there is little airframe/engine interaction, and the stability and performance with those control laws is not affected. Implications of parameter uncertainty in the coupling dynamics is also discussed, and effects of these parameter variations are also demonstrated to be small for this vehicle configuration.

Evaluating the sub-national fidelity of national Initiatives in decentralized health systems: Integrated Primary Health Care Governance in Nigeria.

PubMed

Eboreime, Ejemai Amaize; Abimbola, Seye; Obi, Felix Abrahams; Ebirim, Obinna; Olubajo, Olalekan; Eyles, John; Nxumalo, Nonhlanhla Lynette; Mambulu, Faith Nankasa

2017-03-21

Policy making, translation and implementation in politically and administratively decentralized systems can be challenging. Beyond the mere sub-national acceptance of national initiatives, adherence to policy implementation processes is often poor, particularly in low and middle-income countries. In this study, we explore the implementation fidelity of integrated PHC governance policy in Nigeria's decentralized governance system and its implications on closing implementation gaps with respect to other top-down health policies and initiatives. Having engaged policy makers, we identified 9 core components of the policy (Governance, Legislation, Minimum Service Package, Repositioning, Systems Development, Operational Guidelines, Human Resources, Funding Structure, and Office Establishment). We evaluated the level and pattern of implementation at state level as compared to the national guidelines using a scorecard approach. Contrary to national government's assessment of level of compliance, we found that sub-national governments exercised significant discretion with respect to the implementation of core components of the policy. Whereas 35 and 32% of states fully met national criteria for the structural domains of "Office Establishment" and Legislation" respectively, no state was fully compliant to "Human Resource Management" and "Funding" requirements, which are more indicative of functionality. The pattern of implementation suggests that, rather than implementing to improve outcomes, state governments may be more interested in executing low hanging fruits in order to access national incentives. Our study highlights the importance of evaluating implementation fidelity in providing evidence of implementation gaps towards improving policy execution, particularly in decentralized health systems. This approach will help national policy makers identify more effective ways of supporting lower tiers of governance towards improvement of health systems and outcomes.

Morphological communication: exploiting coupled dynamics in a complex mechanical structure to achieve locomotion

PubMed Central

Rieffel, John A.; Valero-Cuevas, Francisco J.; Lipson, Hod

2010-01-01

Traditional engineering approaches strive to avoid, or actively suppress, nonlinear dynamic coupling among components. Biological systems, in contrast, are often rife with these dynamics. Could there be, in some cases, a benefit to high degrees of dynamical coupling? Here we present a distributed robotic control scheme inspired by the biological phenomenon of tensegrity-based mechanotransduction. This emergence of morphology-as-information-conduit or ‘morphological communication’, enabled by time-sensitive spiking neural networks, presents a new paradigm for the decentralized control of large, coupled, modular systems. These results significantly bolster, both in magnitude and in form, the idea of morphological computation in robotic control. Furthermore, they lend further credence to ideas of embodied anatomical computation in biological systems, on scales ranging from cellular structures up to the tendinous networks of the human hand. PMID:19776146

Centralized vs. decentralized nursing stations: effects on nurses' functional use of space and work environment.

PubMed

Zborowsky, Terri; Bunker-Hellmich, Lou; Morelli, Agneta; O'Neill, Mike

2010-01-01

Evidence-based findings of the effects of nursing station design on nurses' work environment and work behavior are essential to improve conditions and increase retention among these fundamental members of the healthcare delivery team. The purpose of this exploratory study was to investigate how nursing station design (i.e., centralized and decentralized nursing station layouts) affected nurses' use of space, patient visibility, noise levels, and perceptions of the work environment. Advances in information technology have enabled nurses to move away from traditional centralized paper-charting stations to smaller decentralized work stations and charting substations located closer to, or inside of, patient rooms. Improved understanding of the trade-offs presented by centralized and decentralized nursing station design has the potential to provide useful information for future nursing station layouts. This information will be critical for understanding the nurse environment "fit." The study used an exploratory design with both qualitative and quantitative methods. Qualitative data regarding the effects of nursing station design on nurses' health and work environment were gathered by means of focus group interviews. Quantitative data-gathering techniques included place- and person-centered space use observations, patient visibility assessments, sound level measurements, and an online questionnaire regarding perceptions of the work environment. Nurses on all units were observed most frequently performing telephone, computer, and administrative duties. Time spent using telephones, computers, and performing other administrative duties was significantly higher in the centralized nursing stations. Consultations with medical staff and social interactions were significantly less frequent in decentralized nursing stations. There were no indications that either centralized or decentralized nursing station designs resulted in superior visibility. Sound levels measured in all nursing stations exceeded recommended levels during all shifts. No significant differences were identified in nurses' perceptions of work control-demand-support in centralized and decentralized nursing station designs. The "hybrid" nursing design model in which decentralized nursing stations are coupled with centralized meeting rooms for consultation between staff members may strike a balance between the increase in computer duties and the ongoing need for communication and consultation that addresses the conflicting demands of technology and direct patient care.

Multicoordination Control Strategy Performance in Hybrid Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezzini, Paolo; Bryden, Kenneth M.; Tucker, David

This paper evaluates a state-space methodology of a multi-input multi-output (MIMO) control strategy using a 2 × 2 tightly coupled scenario applied to a physical gas turbine fuel cell hybrid power system. A centralized MIMO controller was preferred compared to a decentralized control approach because previous simulation studies showed that the coupling effect identified during the simultaneous control of the turbine speed and cathode airflow was better minimized. The MIMO controller was developed using a state-space dynamic model of the system that was derived using first-order transfer functions empirically obtained through experimental tests. The controller performance was evaluated in termsmore » of disturbance rejection through perturbations in the gas turbine operation, and setpoint tracking maneuver through turbine speed and cathode airflow steps. The experimental results illustrate that a multicoordination control strategy was able to mitigate the coupling of each actuator to each output during the simultaneous control of the system, and improved the overall system performance during transient conditions. On the other hand, the controller showed different performance during validation in simulation environment compared to validation in the physical facility, which will require a better dynamic modeling of the system for the implementation of future multivariable control strategies.« less

Multicoordination Control Strategy Performance in Hybrid Power Systems

DOE PAGES

Pezzini, Paolo; Bryden, Kenneth M.; Tucker, David

2018-04-11

This paper evaluates a state-space methodology of a multi-input multi-output (MIMO) control strategy using a 2 × 2 tightly coupled scenario applied to a physical gas turbine fuel cell hybrid power system. A centralized MIMO controller was preferred compared to a decentralized control approach because previous simulation studies showed that the coupling effect identified during the simultaneous control of the turbine speed and cathode airflow was better minimized. The MIMO controller was developed using a state-space dynamic model of the system that was derived using first-order transfer functions empirically obtained through experimental tests. The controller performance was evaluated in termsmore » of disturbance rejection through perturbations in the gas turbine operation, and setpoint tracking maneuver through turbine speed and cathode airflow steps. The experimental results illustrate that a multicoordination control strategy was able to mitigate the coupling of each actuator to each output during the simultaneous control of the system, and improved the overall system performance during transient conditions. On the other hand, the controller showed different performance during validation in simulation environment compared to validation in the physical facility, which will require a better dynamic modeling of the system for the implementation of future multivariable control strategies.« less

Hierarchical Decentralized Control Strategy for Demand-Side Primary Frequency Response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, Jianming; Hansen, Jacob; Marinovici, Laurentiu D.

The Grid Friendlymore » $$^\\textrm{TM}$$ Appliance~(GFA) controller, developed at Pacific Northwest National Laboratory, was designed for the purpose of autonomously switching off appliances by detecting under-frequency events. In this paper, a new frequency responsive load~(FRL) controller is first proposed by extending the functionality of the original GFA controller. The proposed FRL controller can autonomously switch on (or off) end-use loads by detecting over-frequency (or under-frequency) events through local frequency measurement. Then, a hierarchical decentralized control framework is developed for engaging the end-use loads to provide primary frequency response with the proposed FRL controller. The developed framework has several important features that are desirable in terms of providing primary frequency control. It not only exclusively maintains the autonomous operation of the end-use loads, but also effectively overcomes the stability issue associated with high penetration of FRLs. The simulation results illustrate the effectiveness of the developed hierarchical control framework for providing primary frequency response with the proposed FRL controller.« less

Decentralized system identification using stochastic subspace identification on wireless smart sensor networks

NASA Astrophysics Data System (ADS)

Sim, Sung-Han; Spencer, Billie F., Jr.; Park, Jongwoong; Jung, Hyungjo

2012-04-01

Wireless Smart Sensor Networks (WSSNs) facilitates a new paradigm to structural identification and monitoring for civil infrastructure. Conventional monitoring systems based on wired sensors and centralized data acquisition and processing have been considered to be challenging and costly due to cabling and expensive equipment and maintenance costs. WSSNs have emerged as a technology that can overcome such difficulties, making deployment of a dense array of sensors on large civil structures both feasible and economical. However, as opposed to wired sensor networks in which centralized data acquisition and processing is common practice, WSSNs require decentralized computing algorithms to reduce data transmission due to the limitation associated with wireless communication. Thus, several system identification methods have been implemented to process sensor data and extract essential information, including Natural Excitation Technique with Eigensystem Realization Algorithm, Frequency Domain Decomposition (FDD), and Random Decrement Technique (RDT); however, Stochastic Subspace Identification (SSI) has not been fully utilized in WSSNs, while SSI has the strong potential to enhance the system identification. This study presents a decentralized system identification using SSI in WSSNs. The approach is implemented on MEMSIC's Imote2 sensor platform and experimentally verified using a 5-story shear building model.

Multi-arm multilateral haptics-based immersive tele-robotic system (HITS) for improvised explosive device disposal

NASA Astrophysics Data System (ADS)

Erickson, David; Lacheray, Hervé; Lai, Gilbert; Haddadi, Amir

2014-06-01

This paper presents the latest advancements of the Haptics-based Immersive Tele-robotic System (HITS) project, a next generation Improvised Explosive Device (IED) disposal (IEDD) robotic interface containing an immersive telepresence environment for a remotely-controlled three-articulated-robotic-arm system. While the haptic feedback enhances the operator's perception of the remote environment, a third teleoperated dexterous arm, equipped with multiple vision sensors and cameras, provides stereo vision with proper visual cues, and a 3D photo-realistic model of the potential IED. This decentralized system combines various capabilities including stable and scaled motion, singularity avoidance, cross-coupled hybrid control, active collision detection and avoidance, compliance control and constrained motion to provide a safe and intuitive control environment for the operators. Experimental results and validation of the current system are presented through various essential IEDD tasks. This project demonstrates that a two-armed anthropomorphic Explosive Ordnance Disposal (EOD) robot interface can achieve complex neutralization techniques against realistic IEDs without the operator approaching at any time.

Decentralized and Modular Electrical Architecture

NASA Astrophysics Data System (ADS)

Elisabelar, Christian; Lebaratoux, Laurence

2014-08-01

This paper presents the studies made on the definition and design of a decentralized and modular electrical architecture that can be used for power distribution, active thermal control (ATC), standard inputs-outputs electrical interfaces.Traditionally implemented inside central unit like OBC or RTU, these interfaces can be dispatched in the satellite by using MicroRTU.CNES propose a similar approach of MicroRTU. The system is based on a bus called BRIO (Bus Réparti des IO), which is composed, by a power bus and a RS485 digital bus. BRIO architecture is made with several miniature terminals called BTCU (BRIO Terminal Control Unit) distributed in the spacecraft.The challenge was to design and develop the BTCU with very little volume, low consumption and low cost. The standard BTCU models are developed and qualified with a configuration dedicated to ATC, while the first flight model will fly on MICROSCOPE for PYRO actuations and analogue acquisitions. The design of the BTCU is made in order to be easily adaptable for all type of electric interface needs.Extension of this concept is envisaged for power conditioning and distribution unit, and a Modular PCDU based on BRIO concept is proposed.

Adaptive Fault-Tolerant Control of Uncertain Nonlinear Large-Scale Systems With Unknown Dead Zone.

PubMed

Chen, Mou; Tao, Gang

2016-08-01

In this paper, an adaptive neural fault-tolerant control scheme is proposed and analyzed for a class of uncertain nonlinear large-scale systems with unknown dead zone and external disturbances. To tackle the unknown nonlinear interaction functions in the large-scale system, the radial basis function neural network (RBFNN) is employed to approximate them. To further handle the unknown approximation errors and the effects of the unknown dead zone and external disturbances, integrated as the compounded disturbances, the corresponding disturbance observers are developed for their estimations. Based on the outputs of the RBFNN and the disturbance observer, the adaptive neural fault-tolerant control scheme is designed for uncertain nonlinear large-scale systems by using a decentralized backstepping technique. The closed-loop stability of the adaptive control system is rigorously proved via Lyapunov analysis and the satisfactory tracking performance is achieved under the integrated effects of unknown dead zone, actuator fault, and unknown external disturbances. Simulation results of a mass-spring-damper system are given to illustrate the effectiveness of the proposed adaptive neural fault-tolerant control scheme for uncertain nonlinear large-scale systems.

Semi-active friction damper for buildings subject to seismic excitation

NASA Astrophysics Data System (ADS)

Mantilla, Juan S.; Solarte, Alexander; Gomez, Daniel; Marulanda, Johannio; Thomson, Peter

2016-04-01

Structural control systems are considered an effective alternative for reducing vibrations in civil structures and are classified according to their energy supply requirement: passive, semi-active, active and hybrid. Commonly used structural control systems in buildings are passive friction dampers, which add energy dissipation through damping mechanisms induced by sliding friction between their surfaces. Semi-Active Variable Friction Dampers (SAVFD) allow the optimum efficiency range of friction dampers to be enhanced by controlling the clamping force in real time. This paper describes the development and performance evaluation of a low-cost SAVFD for the reduction of vibrations of structures subject to earthquakes. The SAVFD and a benchmark structural control test structure were experimentally characterized and analytical models were developed and updated based on the dynamic characterization. Decentralized control algorithms were implemented and tested on a shaking table. Relative displacements and accelerations of the structure controlled with the SAVFD were 80% less than those of the uncontrolled structure

Retention in Differentiated Care: Multiple Measures Analysis for a Decentralized HIV Care and Treatment Program in North Central Nigeria

PubMed Central

Agaba, Patricia A; Genberg, Becky L; Sagay, Atiene S; Agbaji, Oche O; Meloni, Seema T; Dadem, Nancin Y; Kolawole, Grace O; Okonkwo, Prosper; Kanki, Phyllis J; Ware, Norma C

2018-01-01

Objective Differentiated care refers collectively to flexible service models designed to meet the differing needs of HIV-infected persons in resource-scarce settings. Decentralization is one such service model. Retention is a key indicator for monitoring the success of HIV treatment and care programs. We used multiple measures to compare retention in a cohort of patients receiving HIV care at “hub” (central) and “spoke” (decentralized) sites in a large public HIV treatment program in north central Nigeria. Methods This retrospective cohort study utilized longitudinal program data representing central and decentralized levels of care in the Plateau State Decentralization Initiative, north central Nigeria. We examined retention with patient- level (retention at fixed times, loss-to-follow-up [LTFU]) and visit-level (gaps-in-care, visit constancy) measures. Regression models with generalized estimating equations (GEE) were used to estimate the effect of decentralization on visit-level measures. Patient-level measures were examined using survival methods with Cox regression models, controlling for baseline variables. Results Of 15,650 patients, 43% were enrolled at the hub. Median time in care was 3.1 years. Hub patients were less likely to be LTFU (adjusted hazard ratio (AHR)=0.91, 95% CI: 0.85-0.97), compared to spoke patients. Visit constancy was lower at the hub (−4.5%, 95% CI: −3.5, −5.5), where gaps in care were also more likely to occur (adjusted odds ratio=1.95, 95% CI: 1.83-2.08). Conclusion Decentralized sites demonstrated better retention outcomes using visit-level measures, while the hub achieved better retention outcomes using patient-level measures. Retention estimates produced by incorporating multiple measures showed substantial variation, confirming the influence of measurement strategies on the results of retention research. Future studies of retention in HIV care in sub-Saharan Africa will be well-served by including multiple measures. PMID:29682399

Retention in Differentiated Care: Multiple Measures Analysis for a Decentralized HIV Care and Treatment Program in North Central Nigeria.

PubMed

Agaba, Patricia A; Genberg, Becky L; Sagay, Atiene S; Agbaji, Oche O; Meloni, Seema T; Dadem, Nancin Y; Kolawole, Grace O; Okonkwo, Prosper; Kanki, Phyllis J; Ware, Norma C

2018-01-01

Differentiated care refers collectively to flexible service models designed to meet the differing needs of HIV-infected persons in resource-scarce settings. Decentralization is one such service model. Retention is a key indicator for monitoring the success of HIV treatment and care programs. We used multiple measures to compare retention in a cohort of patients receiving HIV care at "hub" (central) and "spoke" (decentralized) sites in a large public HIV treatment program in north central Nigeria. This retrospective cohort study utilized longitudinal program data representing central and decentralized levels of care in the Plateau State Decentralization Initiative, north central Nigeria. We examined retention with patient- level (retention at fixed times, loss-to-follow-up [LTFU]) and visit-level (gaps-in-care, visit constancy) measures. Regression models with generalized estimating equations (GEE) were used to estimate the effect of decentralization on visit-level measures. Patient-level measures were examined using survival methods with Cox regression models, controlling for baseline variables. Of 15,650 patients, 43% were enrolled at the hub. Median time in care was 3.1 years. Hub patients were less likely to be LTFU (adjusted hazard ratio (AHR)=0.91, 95% CI: 0.85-0.97), compared to spoke patients. Visit constancy was lower at the hub (-4.5%, 95% CI: -3.5, -5.5), where gaps in care were also more likely to occur (adjusted odds ratio=1.95, 95% CI: 1.83-2.08). Decentralized sites demonstrated better retention outcomes using visit-level measures, while the hub achieved better retention outcomes using patient-level measures. Retention estimates produced by incorporating multiple measures showed substantial variation, confirming the influence of measurement strategies on the results of retention research. Future studies of retention in HIV care in sub-Saharan Africa will be well-served by including multiple measures.

Decision Space and Capacities in the Decentralization of Health Services in FijiComment on "Decentralisation of Health Services in Fiji: A Decision Space Analysis".

PubMed

Bossert, Thomas J

2016-05-08

The study of decentralization in Fiji shows that increasing capacities is not necessarily related to increasing decision space of local officials, which is in contrast with earlier studies in Pakistan. Future studies should address the relationship among decision space, capacities, and health system performance. © 2016 by Kerman University of Medical Sciences.

Fiscal decentralization in the Italian NHS: what happens to interregional redistribution?

PubMed

Ferrario, Caterina; Zanardi, Alberto

2011-04-01

This paper explores how pressures for an increased decentralization of taxing powers to sub-national governments may affect the degree of income redistribution across regional territories accomplished by the Italian NHS. In Italy, political responsibilities for health care are decentralized to regional governments, but the central government retains a critical role in ensuring all citizens uniform access to health services. To this end the central government runs an expenditure needs equalizing system to top up regional governments own resources. However, this system is currently put under question by strong political pressures calling for a weakening of central government involvement. Applying a well developed econometric approach we find that the NHS currently reduces interregional differences in per-capita income by about 7% of GDP. A reform of the NHS in terms of a reduction of expenditure standards produces a weakening of redistribution across jurisdictions, the size of which crucially depends on the financing arrangements of health care that will be actually adopted. We conclude that the decentralization of the NHS would give rise to relevant policy issues concerning in particular the different health care spending possibilities across regions and the impact on the interregional mobility of patients. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Distributed architecture and distributed processing mode in urban sewage treatment

NASA Astrophysics Data System (ADS)

Zhou, Ruipeng; Yang, Yuanming

2017-05-01

Decentralized rural sewage treatment facility over the broad area, a larger operation and management difficult, based on the analysis of rural sewage treatment model based on the response to these challenges, we describe the principle, structure and function in networking technology and network communications technology as the core of distributed remote monitoring system, through the application of case analysis to explore remote monitoring system features in a decentralized rural sewage treatment facilities in the daily operation and management. Practice shows that the remote monitoring system to provide technical support for the long-term operation and effective supervision of the facilities, and reduced operating, maintenance and supervision costs for development.

Experimenting with Decentralization: The Politics of Change.

ERIC Educational Resources Information Center

Wohlstetter, Priscilla

The relationship between the political context of school districts and their choices of decentralization policy is explored in this paper. It was expected that district politics would affect decentralization policies in two ways: the form of decentralization adopted and the degree of change. The decision to decentralize in three large urban school…

An Artificially Intelligent Physical Model-Checking Approach to Detect Switching-Related Attacks on Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

El Hariri, Mohamad; Faddel, Samy; Mohammed, Osama

Decentralized and hierarchical microgrid control strategies have lain the groundwork for shaping the future smart grid. Such control approaches require the cooperation between microgrid operators in control centers, intelligent microcontrollers, and remote terminal units via secure and reliable communication networks. In order to enhance the security and complement the work of network intrusion detection systems, this paper presents an artificially intelligent physical model-checking that detects tampered-with circuit breaker switching control commands whether, due to a cyber-attack or human error. In this technique, distributed agents, which are monitoring sectionalized areas of a given microgrid, will be trained and continuously adapted tomore » verify that incoming control commands do not violate the physical system operational standards and do not put the microgrid in an insecure state. The potential of this approach has been tested by deploying agents that monitor circuit breakers status commands on a 14-bus IEEE benchmark system. The results showed the accuracy of the proposed framework in characterizing the power system and successfully detecting malicious and/or erroneous control commands.« less

A Framework for Information Theoretic Cooperative Sensing and Predictive Control

DTIC Science & Technology

2012-09-11

Miroslav Barić and Francesco Borelli , Decentralized Robust Control Invariance for a Network of Integrators, Proceeding of American Control...from http: //www.mpc.berkeley.edu. P4 Miroslav Barić and Francesco Borelli , Distributed Averaging with Flow Constraints, Proceeding of American Control

A Decentralized VPN Service over Generalized Mobile Ad-Hoc Networks

NASA Astrophysics Data System (ADS)

Fujita, Sho; Shima, Keiichi; Uo, Yojiro; Esaki, Hiroshi

We present a decentralized VPN service that can be built over generalized mobile ad-hoc networks (Generalized MANETs), in which topologies can be represented as a time-varying directed multigraph. We address wireless ad-hoc networks and overlay ad-hoc networks as instances of Generalized MANETs. We first propose an architecture to operate on various kinds of networks through a single set of operations. Then, we design and implement a decentralized VPN service on the proposed architecture. Through the development and operation of a prototype system we implemented, we found that the proposed architecture makes the VPN service applicable to each instance of Generalized MANETs, and that the VPN service makes it possible for unmodified applications to operate on the networks.

Septic Systems Case Studies

EPA Pesticide Factsheets

A collection of septic systems case studies to help community planners, elected officials, health department staff, state officials, and interested citizens explore alternatives for managing their decentralized wastewater treatment systems.

An ecological vegetation-activated sludge process (V-ASP) for decentralized wastewater treatment: system development, treatment performance, and mathematical modeling.

PubMed

Yuan, Jiajia; Dong, Wenyi; Sun, Feiyun; Li, Pu; Zhao, Ke

2016-05-01

An environment-friendly decentralized wastewater treatment process that is comprised of activated sludge process (ASP) and wetland vegetation, named as vegetation-activated sludge process (V-ASP), was developed for decentralized wastewater treatment. The long-term experimental results evidenced that the vegetation sequencing batch reactor (V-SBR) process had consistently stable higher removal efficiencies of organic substances and nutrients from domestic wastewater compared with traditional sequencing batch reactor (SBR). The vegetation allocated into V-SBR system could not only remove nutrients through its vegetation transpiration ratio but also provide great surface area for microorganism activity enhancement. This high vegetation transpiration ratio enhanced nutrients removal effectiveness from wastewater mainly by flux enhancement, oxygen and substrate transportation acceleration, and vegetation respiration stimulation. A mathematical model based on ASM2d was successfully established by involving the specific function of vegetation to simulate system performance. The simulation results on the influence of operational parameters on V-ASP treatment effectiveness demonstrated that V-SBR had a high resistance to seasonal temperature fluctuations and influent loading shocking.

Decentralization and health system performance - a focused review of dimensions, difficulties, and derivatives in India.

PubMed

Panda, Bhuputra; Thakur, Harshad P

2016-10-31

One of the principal goals of any health care system is to improve health through the provision of clinical and public health services. Decentralization as a reform measure aims to improve inputs, management processes and health outcomes, and has political, administrative and financial connotations. It is argued that the robustness of a health system in achieving desirable outcomes is contingent upon the width and depth of 'decision space' at the local level. Studies have used different approaches to examine one or more facets of decentralization and its effect on health system functioning; however, lack of consensus on an acceptable framework is a critical gap in determining its quantum and quality. Theorists have resorted to concepts of 'trust', 'convenience' and 'mutual benefits' to explain, define and measure components of governance in health. In the emerging 'continuum of health services' model, the challenge lies in identifying variables of performance (fiscal allocation, autonomy at local level, perception of key stakeholders, service delivery outputs, etc.) through the prism of decentralization in the first place, and in establishing directed relationships among them. This focused review paper conducted extensive web-based literature search, using PubMed and Google Scholar search engines. After screening of key words and study objectives, we retrieved 180 articles for next round of screening. One hundred and four full articles (three working papers and 101 published papers) were reviewed in totality. We attempted to summarize existing literature on decentralization and health systems performance, explain key concepts and essential variables, and develop a framework for further scientific scrutiny. Themes are presented in three separate segments of dimensions, difficulties and derivatives. Evaluation of local decision making and its effect on health system performance has been studied in a compartmentalized manner. There is sparse evidence about innovations attributable to decentralization. We observed that in India, there is very scant evaluative study on the subject. We didn't come across a single study examining the perception and experiences of local decision makers about the opportunities and challenges they faced. The existing body of evidences may be inadequate to feed into sound policy making. The principles of management hinge on measurement of inputs, processes and outputs. In the conceptual framework we propose three levels of functions (health systems functions, management functions and measurement functions) being intricately related to inputs, processes and outputs. Each level of function encompasses essential elements derived from the synthesis of information gathered through literature review and non-participant observation. We observed that it is difficult to quantify characteristics of governance at institutional, system and individual levels except through proxy means. There is an urgent need to sensitize governments and academia about how best more objective evaluation of 'shared governance' can be undertaken to benefit policy making. The future direction of enquiry should focus on context-specific evidence of its effect on the entire spectrum of health system, with special emphasis on efficiency, community participation, human resource management and quality of services.

Dancing with Swarms: Utilizing Swarm Intelligence to Build, Investigate, and Control Complex Systems

NASA Astrophysics Data System (ADS)

Jacob, Christian

We are surrounded by a natural world of massively parallel, decentralized biological "information processing" systems, a world that exhibits fascinating emergent properties in many ways. In fact, our very own bodies are the result of emergent patterns, as the development of any multi-cellular organism is determined by localized interactions among an enormous number of cells, carefully orchestrated by enzymes, signalling proteins and other molecular "agents". What is particularly striking about these highly distributed developmental processes is that a centralized control agency is completely absent. This is also the case for many other biological systems, such as termites which build their nests—without an architect that draws a plan, or brain cells evolving into a complex `mind machine'—without an explicit blueprint of a network layout.

Staggering successes amid controversy in California water management

NASA Astrophysics Data System (ADS)

Lund, J. R.

2012-12-01

Water in California has always been important and controversial, and it probably always will be. California has a large, growing economy and population in a semi-arid climate. But California's aridity, hydrologic variability, and water controversies have not precluded considerable economic successes. The successes of California's water system have stemmed from the decentralization of water management with historically punctuated periods of more centralized strategic decision-making. Decentralized management has allowed California's water users to efficiently explore incremental solutions to water problems, ranging from early local development of water systems (such as Hetch Hetchy, Owens Valley, and numerous local irrigation projects) to more contemporary efforts at water conservation, water markets, wastewater reuse, and conjunctive use of surface and groundwater. In the cacophony of local and stakeholder interests, strategic decisions have been more difficult, and consequently occur less frequently. California state water projects and Sacramento Valley flood control are examples where decades of effort, crises, floods and droughts were needed to mobilize local interests to agree to major strategic decisions. Currently, the state is faced with making strategic environmental and water management decisions regarding its deteriorating Sacramento-San Joaquin Delta. Not surprisingly, human uncertainties and physical and fiscal non-stationarities dominate this process.

Evolution of Query Optimization Methods

NASA Astrophysics Data System (ADS)

Hameurlain, Abdelkader; Morvan, Franck

Query optimization is the most critical phase in query processing. In this paper, we try to describe synthetically the evolution of query optimization methods from uniprocessor relational database systems to data Grid systems through parallel, distributed and data integration systems. We point out a set of parameters to characterize and compare query optimization methods, mainly: (i) size of the search space, (ii) type of method (static or dynamic), (iii) modification types of execution plans (re-optimization or re-scheduling), (iv) level of modification (intra-operator and/or inter-operator), (v) type of event (estimation errors, delay, user preferences), and (vi) nature of decision-making (centralized or decentralized control).

City School District Reorganization: An Annotated Bibliography. Centralization and Decentralization in the Government of Metropolitan Areas with Special Emphasis on the Organization, Administration, and Financing of Large-City School Systems. Educational Research Series No. 1.

ERIC Educational Resources Information Center

Rideout, E. Brock; Najat, Sandra

As a guide to educational administrators working in large cities, abstracts of 161 books, pamphlets, papers, and journal articles published between 1924 and 1966 are classified into five categories: (1) Centralization versus decentralization, (2) local government, (3) metropolitan organization, (4) the financing of education, and (5) the…

Randomly Sampled-Data Control Systems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Han, Kuoruey

1990-01-01

The purpose is to solve the Linear Quadratic Regulator (LQR) problem with random time sampling. Such a sampling scheme may arise from imperfect instrumentation as in the case of sampling jitter. It can also model the stochastic information exchange among decentralized controllers to name just a few. A practical suboptimal controller is proposed with the nice property of mean square stability. The proposed controller is suboptimal in the sense that the control structure is limited to be linear. Because of i. i. d. assumption, this does not seem unreasonable. Once the control structure is fixed, the stochastic discrete optimal control problem is transformed into an equivalent deterministic optimal control problem with dynamics described by the matrix difference equation. The N-horizon control problem is solved using the Lagrange's multiplier method. The infinite horizon control problem is formulated as a classical minimization problem. Assuming existence of solution to the minimization problem, the total system is shown to be mean square stable under certain observability conditions. Computer simulations are performed to illustrate these conditions.

Using community-based evidence for decentralized health planning: insights from Maharashtra, India.

PubMed

Shukla, Abhay; Khanna, Renu; Jadhav, Nitin

2018-01-01

Health planning is generally considered a technical subject, primarily the domain of health officials with minimal involvement of community representatives. The National Rural Health Mission launched in India in 2005 recognized this gap and mandated mechanisms for decentralized health planning. However, since planning develops in the context of highly unequal power relations, formal spaces for participation are necessary but not sufficient. Hence a project on capacity building for decentralized health planning was implemented in selected districts of Maharashtra, India during 2010-13. This process developed on the platform of officially supported community-based monitoring and planning, a process for community feedback and participation towards health system change. A specific project on capacity building for decentralized planning included a structured learning course and workshops for major stakeholders. An evaluation of the project, including in-depth interviews of various participants and analysis of change in local health planning processes, revealed positive changes in intervention areas, including increased capacity of key stakeholders leading to preparation of evidence-based, innovative planning proposals, significant community oriented changes in utilization of health facility funds, and inclusion of community-based proposals in village, health facility-based block and district plans. Transparency related to planning increased along with responsiveness of health providers to community suggestions. A key lesson is that active facilitation of decentralized health planning and influencing the health system to expand participation, are essential to ensure changes in planning. Effective strategies included: identifying people's health service related priorities through community-based monitoring, capacity building of diverse stakeholders regarding local health planning, and advocacy to enable participation of community-based actors in the planning process. This combination of strategies draws upon the framework of 'empowered participatory governance' which necessitates combining a degree of 'countervailing power' and acceptance of participation by the system, for new forms of governance to emerge. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2014; all rights reserved.

Site Management. An Analysis of the Concepts and Fundamental Operational Components Associated with the Delegation of Decision-Making Authority and Control of Resources to the School-Site Level in the California Public School System.

ERIC Educational Resources Information Center

Decker, Erwin A.; And Others

The pros and cons of decentralization of decision-making authority to the school-site level as a public school management technique are intended to serve as an informational summary for the members of the California State Board of Education, and as a resource for school district governing boards and district administrators to use to determine the…

Decentralizing conservation and diversifying livelihoods within Kanchenjunga Conservation Area, Nepal.

PubMed

Parker, Pete; Thapa, Brijesh; Jacob, Aerin

2015-12-01

To alleviate poverty and enhance conservation in resource dependent communities, managers must identify existing livelihood strategies and the associated factors that impede household access to livelihood assets. Researchers increasingly advocate reallocating management power from exclusionary central institutions to a decentralized system of management based on local and inclusive participation. However, it is yet to be shown if decentralizing conservation leads to diversified livelihoods within a protected area. The purpose of this study was to identify and assess factors affecting household livelihood diversification within Nepal's Kanchenjunga Conservation Area Project, the first protected area in Asia to decentralize conservation. We randomly surveyed 25% of Kanchenjunga households to assess household socioeconomic and demographic characteristics and access to livelihood assets. We used a cluster analysis with the ten most common income generating activities (both on- and off-farm) to group the strategies households use to diversify livelihoods, and a multinomial logistic regression to identify predictors of livelihood diversification. We found four distinct groups of household livelihood strategies with a range of diversification that directly corresponded to household income. The predictors of livelihood diversification were more related to pre-existing socioeconomic and demographic factors (e.g., more landholdings and livestock, fewer dependents, receiving remittances) than activities sponsored by decentralizing conservation (e.g., microcredit, training, education, interaction with project staff). Taken together, our findings indicate that without direct policies to target marginalized groups, decentralized conservation in Kanchenjunga will continue to exclude marginalized groups, limiting a household's ability to diversify their livelihood and perpetuating their dependence on natural resources. Copyright © 2015 Elsevier Ltd. All rights reserved.

Expansion of a residency program through provision of second-shift decentralized services.

PubMed

Host, Brian D; Anderson, Michael J; Lucas, Paul D

2014-12-15

The rationale for and logistics of the expansion of a postgraduate year 1 (PGY1) residency program in a community hospital are described. Baptist Health Lexington, a nonprofit community hospital in Lexington, Kentucky, sought to expand the PGY1 program by having residents perform second-shift decentralized pharmacist functions. Program expansion was predicated on aligning resident staffing functions with current hospitalwide initiatives involving medication reconciliation and patient education. The focus was to integrate residents into the workflow while allowing them more time to practice as pharmacists and contribute to departmental objectives. The staffing function would increase residents' overall knowledge of departmental operations and foster their sense of independence and ownership. The decentralized functions would include initiation of clinical pharmacokinetic consultations, admission medication reconciliation, discharge teaching for patients with heart failure, and order-entry support from decentralized locations. The program grew from three to five residents and established a staffing rotation for second-shift decentralized coverage. The increased time spent staffing did not detract from the time allotted to previously established learning experiences and enhanced overall continuity of the staffing experience. The change also emphasized to the residents the importance of integration of distributive and clinical functions within the department. Pharmacist participation in admission and discharge medication reconciliation activities has also increased patient satisfaction, evidenced by follow-up surveys conducted by the hospital. A PGY1 residency program was expanded through the provision of second-shift decentralized clinical services, which helped provide residents with increased patient exposure and enhanced staffing experience. Copyright © 2014 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Correlated-Data Fusion and Cooperative Aiding in GNSS-Stressed or Denied Environments

NASA Astrophysics Data System (ADS)

Mokhtarzadeh, Hamid

A growing number of applications require continuous and reliable estimates of position, velocity, and orientation. Price requirements alone disqualify most traditional navigation or tactical-grade sensors and thus navigation systems based on automotive or consumer-grade sensors aided by Global Navigation Satellite Systems (GNSS), like the Global Positioning System (GPS), have gained popularity. The heavy reliance on GPS in these navigation systems is a point of concern and has created interest in alternative or back-up navigation systems to enable robust navigation through GPS-denied or stressed environments. This work takes advantage of current trends for increased sensing capabilities coupled with multilayer connectivity to propose a cooperative navigation-based aiding system as a means to limit dead reckoning error growth in the absence of absolute measurements like GPS. Each vehicle carries a dead reckoning navigation system which is aided by relative measurements, like range, to neighboring vehicles together with information sharing. Detailed architectures and concepts of operation are described for three specific applications: commercial aviation, Unmanned Aerial Vehicles (UAVs), and automotive applications. Both centralized and decentralized implementations of cooperative navigation-based aiding systems are described. The centralized system is based on a single Extended Kalman Filter (EKF). A decentralized implementation suited for applications with very limited communication bandwidth is discussed in detail. The presence of unknown correlation between the a priori state and measurement errors makes the standard Kalman filter unsuitable. Two existing estimators for handling this unknown correlation are Covariance Intersection (CI) and Bounded Covariance Inflation (BCInf) filters. A CI-based decentralized estimator suitable for decentralized cooperative navigation implementation is proposed. A unified derivation is presented for the Kalman filter, CI filter, and BCInf filter measurement update equations. Furthermore, characteristics important to the proper implementation of CI and BCInf in practice are discussed. A new covariance normalization step is proposed as necessary to properly apply CI or BCInf. Lastly, both centralized and decentralized implementations of cooperative aiding are analyzed and evaluated using experimental data in the three applications. In the commercial aviation study aircraft are simulated to use their Automatic Dependent Surveillance - Broadcast (ADS-B) and Traffic Collision Avoidance System (TCAS) systems to cooperatively aid their on board INS during a 60 min GPS outage in the national airspace. An availability study of cooperative navigation as proposed in this work around representative United States airports is performed. Availabilities between 70-100% were common at major airports like LGA and MSP in a 30 nmi radius around the airport during morning to evening hours. A GPS-denied navigation system for small UAVs based on cooperative information sharing is described. Experimentally collected flight data from 7 small UAV flights are played-back to evaluate the performance of the navigation system. The results show that the most effective of the architectures can lead to 5+ minutes of navigation without GPS maintaining position errors less than 200 m (1-sigma). The automotive case study considers 15 minutes of automotive traffic (2,000 + vehicles) driving through a half-mile stretch of highway without access to GPS. Automotive radar coupled with Dedicated Short Range Communication (DSRC) protocol are used to implement cooperative aiding to a low-cost 2-D INS on board each vehicle. The centralized system achieves an order of magnitude reduction in uncertainty by aggressively aiding the INS on board each vehicle. The proposed CI-based decentralized estimator is demonstrated to be conservative and maintain consistency. A quantitative analysis of bandwidth requirements shows that the proposed decentralized estimator falls comfortably within modern connectivity capabilities. A naive implementation of the high-performance centralized estimator is also achievable, but it was demonstrated to be burdensome, nearing the bandwidth limits.

U-Form vs. M-Form: How to Understand Decision Autonomy Under Healthcare Decentralization?

PubMed Central

Bustamante, Arturo Vargas

2016-01-01

For more than three decades healthcare decentralization has been promoted in developing countries as a way of improving the financing and delivery of public healthcare. Decision autonomy under healthcare decentralization would determine the role and scope of responsibility of local authorities. Jalal Mohammed, Nicola North, and Toni Ashton analyze decision autonomy within decentralized services in Fiji. They conclude that the narrow decision space allowed to local entities might have limited the benefits of decentralization on users and providers. To discuss the costs and benefits of healthcare decentralization this paper uses the U-form and M-form typology to further illustrate the role of decision autonomy under healthcare decentralization. This paper argues that when evaluating healthcare decentralization, it is important to determine whether the benefits from decentralization are greater than its costs. The U-form and M-form framework is proposed as a useful typology to evaluate different types of institutional arrangements under healthcare decentralization. Under this model, the more decentralized organizational form (M-form) is superior if the benefits from flexibility exceed the costs of duplication and the more centralized organizational form (U-form) is superior if the savings from economies of scale outweigh the costly decision-making process from the center to the regions. Budgetary and financial autonomy and effective mechanisms to maintain local governments accountable for their spending behavior are key decision autonomy variables that could sway the cost-benefit analysis of healthcare decentralization. PMID:27694684

Robust decentralized controller for minimizing coupling effect in single inductor multiple output DC-DC converter operating in continuous conduction mode.

PubMed

Medeiros, Renan Landau Paiva de; Barra, Walter; Bessa, Iury Valente de; Chaves Filho, João Edgar; Ayres, Florindo Antonio de Cavalho; Neves, Cleonor Crescêncio das

2018-02-01

This paper describes a novel robust decentralized control design methodology for a single inductor multiple output (SIMO) DC-DC converter. Based on a nominal multiple input multiple output (MIMO) plant model and performance requirements, a pairing input-output analysis is performed to select the suitable input to control each output aiming to attenuate the loop coupling. Thus, the plant uncertainty limits are selected and expressed in interval form with parameter values of the plant model. A single inductor dual output (SIDO) DC-DC buck converter board is developed for experimental tests. The experimental results show that the proposed methodology can maintain a desirable performance even in the presence of parametric uncertainties. Furthermore, the performance indexes calculated from experimental data show that the proposed methodology outperforms classical MIMO control techniques. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Optical zone centration: a retrospective analysis of the excimer laser after three years

NASA Astrophysics Data System (ADS)

Vervecken, Filip; Trau, Rene; Mertens, Erik L.; Vanhorenbeeck, R.; Van Aerde, F.; Zen, J.; Haustrate, F.; Tassignon, Marie J.

1996-12-01

The aim of this study was to evaluate the implication of the mechanical factor 'decentration' on the visual outcome after PRK. 100 eyes of 70 patients were included. The mean decentration was 0.27 mm +/- 0.18. Decentration was less than 0.5 mm in 84 percent of the cases. The importance of the decentration was investigated by the statistical correlation of decentration from the pupilcenter and the visual outcome. We did not find any statistical significant association for decentrations less than 1 mm. Our conclusion is that decentration, if less than 1 mm, does not play an important role in the final visual outcome after PRK.

Decentralized learning in Markov games.

PubMed

Vrancx, Peter; Verbeeck, Katja; Nowé, Ann

2008-08-01

Learning automata (LA) were recently shown to be valuable tools for designing multiagent reinforcement learning algorithms. One of the principal contributions of the LA theory is that a set of decentralized independent LA is able to control a finite Markov chain with unknown transition probabilities and rewards. In this paper, we propose to extend this algorithm to Markov games--a straightforward extension of single-agent Markov decision problems to distributed multiagent decision problems. We show that under the same ergodic assumptions of the original theorem, the extended algorithm will converge to a pure equilibrium point between agent policies.

Human resources for health at the district level in Indonesia: the smoke and mirrors of decentralization.

PubMed

Heywood, Peter F; Harahap, Nida P

2009-02-03

In 2001 Indonesia embarked on a rapid decentralization of government finances and functions to district governments. One of the results is that government has less information about its most valuable resource, the people who provide the services. The objective of the work reported here is to determine the stock of human resources for health in 15 districts, their service status and primary place of work. It also assesses the effect of decentralization on management of human resources and the implications for the future. We enumerated all health care providers (doctors, nurses and midwives), including information on their employment status and primary place of work, in each of 15 districts in Java. Data were collected by three teams, one for each province. Provider density (number of doctors, nurses and midwives/1000 population) was low by international standards--11 out of 15 districts had provider densities less than 1.0. Approximately half of all three professional groups were permanent public servants. Contractual employment was also important for both nurses and midwives. The private sector as the primary source of employment is most important for doctors (37% overall) and increasingly so for midwives (10%). For those employed in the public sector, two-thirds of doctors and nurses work in health centres, while most midwives are located at village-level health facilities. In the health system established after Independence, the facilities established were staffed through a period of obligatory service for all new graduates in medicine, nursing and midwifery. The last elements of that staffing system ended in 2007 and the government has not been able to replace it. The private sector is expanding and, despite the fact that it will be of increasing importance in the coming decades, government information about providers in private practice is decreasing. Despite the promise of decentralization to increase sectoral "decision space" at the district level, the central government now has control over essentially all public sector health staff at the district level, marking a return to the situation of 20 years ago. At the same time, Indonesia has changed dramatically. The challenge now is to envision a new health system that takes account of these changes. Envisioning the new system is a crucial first step for development of a human resources policy which, in turn, will require more information about health care providers, public and private, and increased capacity for human resource planning.

Does fiscal decentralization improve health outcomes? Evidence from infant mortality in Italy.

PubMed

Cavalieri, Marina; Ferrante, Livio

2016-09-01

Despite financial and decision-making responsibilities having been increasingly devolved to lower levels of government worldwide, the potential impact of these reforms remains largely controversial. This paper investigates the hypothesis that a shift towards a higher degree of fiscal autonomy of sub-national governments could improve health outcomes, as measured by infant mortality rates. Italy is used as a case study since responsibilities for healthcare have been decentralized to regions, though the central government still retains a key role in ensuring all citizens uniform access to health services throughout the country. A linear fixed-effects regression model with robust standard errors is employed for a panel of 20 regions over the period 1996-2012 (340 observations in the full sample). Decentralization is proxied by two different indicators, capturing the degree of decision-making autonomy in the allocation of tax revenues and the extent to which regions rely on fiscal transfers from the central government. The results show that a higher proportion of tax revenues raised and/or controlled locally as well as a lower transfer dependency from the central government are consistently associated with lower infant mortality rates, ceteris paribus. The marginal benefit from fiscal decentralization, however, is not constant but depends on the level of regional wealth, favouring poorest regions. In terms of policy implications, this study outlines how the effectiveness of decentralization in improving health outcomes is contingent on the characteristics of the context in which the process takes place. Copyright © 2016 Elsevier Ltd. All rights reserved.

HMIS and decision-making in Zambia: re-thinking information solutions for district health management in decentralized health systems.

PubMed

Mutemwa, Richard I

2006-01-01

At the onset of health system decentralization as a primary health care strategy, which constituted a key feature of health sector reforms across the developing world, efficient and effective health management information systems (HMIS) were widely acknowledged and adopted as a critical element of district health management strengthening programmes. The focal concern was about the performance and long-term sustainability of decentralized district health systems. The underlying logic was that effective and efficient HMIS would provide district health managers with the information required to make effective strategic decisions that are the vehicle for district performance and sustainability in these decentralized health systems. However, this argument is rooted in normative management and decision theory without significant unequivocal empirical corroboration. Indeed, extensive empirical evidence continues to indicate that managers' decision-making behaviour and the existence of other forms of information outside the HMIS, within the organizational environment, suggest a far more tenuous relationship between the presence of organizational management information systems (such as HMIS) and effective strategic decision-making. This qualitative comparative case-study conducted in two districts of Zambia focused on investigating the presence and behaviour of five formally identified, different information forms, including that from HMIS, in the strategic decision-making process. The aim was to determine the validity of current arguments for HMIS, and establish implications for current HMIS policies. Evidence from the eight strategic decision-making processes traced in the study confirmed the existence of different forms of information in the organizational environment, including that provided by the conventional HMIS. These information forms attach themselves to various organizational management processes and key aspects of organizational routine. The study results point to the need for a radical re-think of district health management information solutions in ways that account for the existence of other information forms outside the formal HMIS in the district health system.

Centralized vs decentralized lunar power system study

NASA Astrophysics Data System (ADS)

Metcalf, Kenneth; Harty, Richard B.; Perronne, Gerald E.

1991-09-01

Three power-system options are considered with respect to utilization on a lunar base: the fully centralized option, the fully decentralized option, and a hybrid comprising features of the first two options. Power source, power conditioning, and power transmission are considered separately, and each architecture option is examined with ac and dc distribution, high and low voltage transmission, and buried and suspended cables. Assessments are made on the basis of mass, technological complexity, cost, reliability, and installation complexity, however, a preferred power-system architecture is not proposed. Preferred options include transmission based on ac, transmission voltages of 2000-7000 V with buried high-voltage lines and suspended low-voltage lines. Assessments of the total cost associated with the installations are required to determine the most suitable power system.

From decentralization to commonization of HIV healthcare resources: keys to reduction in health disparity and equitable distribution of health services in Nigeria.

PubMed

Oleribe, Obinna Ositadimma; Oladipo, Olabisi Abiodun; Ezieme, Iheaka Paul; Crossey, Mary Margaret Elizabeth; Taylor-Robinson, Simon David

2016-01-01

Access to quality care is essential for improved health outcomes. Decentralization improves access to healthcare services at lower levels of care, but it does not dismantle structural, funding and programming restrictions to access, resulting in inequity and inequality in population health. Unlike decentralization, Commonization Model of care reduces health inequalities and inequity, dismantles structural, funding and other program related obstacles to population health. Excellence and Friends Management Care Center (EFMC) using Commonization Model (CM), fully integrated HIV services into core health services in 121 supported facilities. This initiative improved access to care, treatment, support services, reduced stigmatization/discrimination, and improved uptake of HTC. We call on governments to adequately finance CM for health systems restructuring towards better health outcomes.

Balancing Officer Community Manpower through Decentralization: Granular Programming Revisited (1REV)

DTIC Science & Technology

2017-08-01

supply-demand imbalances Economic theory identifies costs and benefits associated with decentralization. On the benefits side, decentralized decision...patterns rather than costs . Granular programming as a decentralized, market-based initiative The costs and benefits of decentralized (instead of...paygrade-specific rates were based on average MPN costs by paygrade. The benefits of this approach to granular programming are that it is conceptually

SimBOX: a scalable architecture for aggregate distributed command and control of spaceport and service constellation

NASA Astrophysics Data System (ADS)

Prasad, Guru; Jayaram, Sanjay; Ward, Jami; Gupta, Pankaj

2004-08-01

In this paper, Aximetric proposes a decentralized Command and Control (C2) architecture for a distributed control of a cluster of on-board health monitoring and software enabled control systems called SimBOX that will use some of the real-time infrastructure (RTI) functionality from the current military real-time simulation architecture. The uniqueness of the approach is to provide a "plug and play environment" for various system components that run at various data rates (Hz) and the ability to replicate or transfer C2 operations to various subsystems in a scalable manner. This is possible by providing a communication bus called "Distributed Shared Data Bus" and a distributed computing environment used to scale the control needs by providing a self-contained computing, data logging and control function module that can be rapidly reconfigured to perform different functions. This kind of software-enabled control is very much needed to meet the needs of future aerospace command and control functions.

SimBox: a simulation-based scalable architecture for distributed command and control of spaceport and service constellations

NASA Astrophysics Data System (ADS)

Prasad, Guru; Jayaram, Sanjay; Ward, Jami; Gupta, Pankaj

2004-09-01

In this paper, Aximetric proposes a decentralized Command and Control (C2) architecture for a distributed control of a cluster of on-board health monitoring and software enabled control systems called SimBOX that will use some of the real-time infrastructure (RTI) functionality from the current military real-time simulation architecture. The uniqueness of the approach is to provide a "plug and play environment" for various system components that run at various data rates (Hz) and the ability to replicate or transfer C2 operations to various subsystems in a scalable manner. This is possible by providing a communication bus called "Distributed Shared Data Bus" and a distributed computing environment used to scale the control needs by providing a self-contained computing, data logging and control function module that can be rapidly reconfigured to perform different functions. This kind of software-enabled control is very much needed to meet the needs of future aerospace command and control functions.

U-Form vs. M-Form: How to Understand Decision Autonomy Under Healthcare Decentralization? Comment on "Decentralisation of Health Services in Fiji: A Decision Space Analysis".

PubMed

Bustamante, Arturo Vargas

2016-06-07

For more than three decades healthcare decentralization has been promoted in developing countries as a way of improving the financing and delivery of public healthcare. Decision autonomy under healthcare decentralization would determine the role and scope of responsibility of local authorities. Jalal Mohammed, Nicola North, and Toni Ashton analyze decision autonomy within decentralized services in Fiji. They conclude that the narrow decision space allowed to local entities might have limited the benefits of decentralization on users and providers. To discuss the costs and benefits of healthcare decentralization this paper uses the U-form and M-form typology to further illustrate the role of decision autonomy under healthcare decentralization. This paper argues that when evaluating healthcare decentralization, it is important to determine whether the benefits from decentralization are greater than its costs. The U-form and M-form framework is proposed as a useful typology to evaluate different types of institutional arrangements under healthcare decentralization. Under this model, the more decentralized organizational form (M-form) is superior if the benefits from flexibility exceed the costs of duplication and the more centralized organizational form (U-form) is superior if the savings from economies of scale outweigh the costly decision-making process from the center to the regions. Budgetary and financial autonomy and effective mechanisms to maintain local governments accountable for their spending behavior are key decision autonomy variables that could sway the cost-benefit analysis of healthcare decentralization. © 2016 by Kerman University of Medical Sciences.

Agent-based Modeling to Simulate the Diffusion of Water-Efficient Innovations and the Emergence of Urban Water Sustainability

NASA Astrophysics Data System (ADS)

Kanta, L.; Giacomoni, M.; Shafiee, M. E.; Berglund, E.

2014-12-01

The sustainability of water resources is threatened by urbanization, as increasing demands deplete water availability, and changes to the landscape alter runoff and the flow regime of receiving water bodies. Utility managers typically manage urban water resources through the use of centralized solutions, such as large reservoirs, which may be limited in their ability balance the needs of urbanization and ecological systems. Decentralized technologies, on the other hand, may improve the health of the water resources system and deliver urban water services. For example, low impact development technologies, such as rainwater harvesting, and water-efficient technologies, such as low-flow faucets and toilets, may be adopted by households to retain rainwater and reduce demands, offsetting the need for new centralized infrastructure. Decentralized technologies may create new complexities in infrastructure and water management, as decentralization depends on community behavior and participation beyond traditional water resources planning. Messages about water shortages and water quality from peers and the water utility managers can influence the adoption of new technologies. As a result, feedbacks between consumers and water resources emerge, creating a complex system. This research develops a framework to simulate the diffusion of water-efficient innovations and the sustainability of urban water resources, by coupling models of households in a community, hydrologic models of a water resources system, and a cellular automata model of land use change. Agent-based models are developed to simulate the land use and water demand decisions of individual households, and behavioral rules are encoded to simulate communication with other agents and adoption of decentralized technologies, using a model of the diffusion of innovation. The framework is applied for an illustrative case study to simulate water resources sustainability over a long-term planning horizon.

Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks.

PubMed

Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

2016-01-01

Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent's limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent's cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent's view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved.

Decentralization and primary health care: some negative implications in developing countries.

PubMed

Collins, C; Green, A

1994-01-01

Decentralization is a highly popular concept, being a key element of Primary Health Care policies. There are, however, certain negative implications of decentralization that must be taken into account. These are analyzed in this article with particular reference to developing countries. The authors criticize the tendency for decentralization to be associated with state limitations, and discuss the dilemma of relating decentralization, which is the enhancement of the different, to equity, which is the promotion of equivalence. Those situations in which decentralization can strengthen political domination are described. The authors conclude by setting out a checklist of warning questions and issues to be taken into account to ensure that decentralization genuinely facilitates the Primary Health Care orientation of health policy.

Patch Transporter: Incentivized, Decentralized Software Patch System for WSN and IoT Environments

PubMed Central

Lee, JongHyup

2018-01-01

In the complicated settings of WSN (Wireless Sensor Networks) and IoT (Internet of Things) environments, keeping a number of heterogeneous devices updated is a challenging job, especially with respect to effectively discovering target devices and rapidly delivering the software updates. In this paper, we convert the traditional software update process to a distributed service. We set an incentive system for faithfully transporting the patches to the recipient devices. The incentive system motivates independent, self-interested transporters for helping the devices to be updated. To ensure the system correctly operates, we employ the blockchain system that enforces the commitment in a decentralized manner. We also present a detailed specification for the proposed protocol and validate it by model checking and simulations for correctness. PMID:29438337

Patch Transporter: Incentivized, Decentralized Software Patch System for WSN and IoT Environments.

PubMed

Lee, JongHyup

2018-02-13

[-12]In the complicated settings of WSN (Wireless Sensor Networks) and IoT (Internet of Things) environments, keeping a number of heterogeneous devices updated is a challenging job, especially with respect to effectively discovering target devices and rapidly delivering the software updates. In this paper, we convert the traditional software update process to a distributed service. We set an incentive system for faithfully transporting the patches to the recipient devices. The incentive system motivates independent, self-interested transporters for helping the devices to be updated. To ensure the system correctly operates, we employ the blockchain system that enforces the commitment in a decentralized manner. We also present a detailed specification for the proposed protocol and validate it by model checking and simulations for correctness.

Modeling a multivariable reactor and on-line model predictive control.

PubMed

Yu, D W; Yu, D L

2005-10-01

A nonlinear first principle model is developed for a laboratory-scaled multivariable chemical reactor rig in this paper and the on-line model predictive control (MPC) is implemented to the rig. The reactor has three variables-temperature, pH, and dissolved oxygen with nonlinear dynamics-and is therefore used as a pilot system for the biochemical industry. A nonlinear discrete-time model is derived for each of the three output variables and their model parameters are estimated from the real data using an adaptive optimization method. The developed model is used in a nonlinear MPC scheme. An accurate multistep-ahead prediction is obtained for MPC, where the extended Kalman filter is used to estimate system unknown states. The on-line control is implemented and a satisfactory tracking performance is achieved. The MPC is compared with three decentralized PID controllers and the advantage of the nonlinear MPC over the PID is clearly shown.

Patient Experiences of Decentralized HIV Treatment and Care in Plateau State, North Central Nigeria: A Qualitative Study

PubMed Central

Kolawole, Grace O.; Gilbert, Hannah N.; Dadem, Nancin Y.; Genberg, Becky L.; Agbaji, Oche O.

2017-01-01

Background. Decentralization of care and treatment for HIV infection in Africa makes services available in local health facilities. Decentralization has been associated with improved retention and comparable or superior treatment outcomes, but patient experiences are not well understood. Methods. We conducted a qualitative study of patient experiences in decentralized HIV care in Plateau State, north central Nigeria. Five decentralized care sites in the Plateau State Decentralization Initiative were purposefully selected. Ninety-three patients and 16 providers at these sites participated in individual interviews and focus groups. Data collection activities were audio-recorded and transcribed. Transcripts were inductively content analyzed to derive descriptive categories representing patient experiences of decentralized care. Results. Patient participants in this study experienced the transition to decentralized care as a series of “trade-offs.” Advantages cited included saving time and money on travel to clinic visits, avoiding dangers on the road, and the “family-like atmosphere” found in some decentralized clinics. Disadvantages were loss of access to ancillary services, reduced opportunities for interaction with providers, and increased risk of disclosure. Participants preferred decentralized services overall. Conclusion. Difficulty and cost of travel remain a fundamental barrier to accessing HIV care outside urban centers, suggesting increased availability of community-based services will be enthusiastically received. PMID:28331636

Patient Experiences of Decentralized HIV Treatment and Care in Plateau State, North Central Nigeria: A Qualitative Study.

PubMed

Kolawole, Grace O; Gilbert, Hannah N; Dadem, Nancin Y; Genberg, Becky L; Agaba, Patricia A; Okonkwo, Prosper; Agbaji, Oche O; Ware, Norma C

2017-01-01

Background. Decentralization of care and treatment for HIV infection in Africa makes services available in local health facilities. Decentralization has been associated with improved retention and comparable or superior treatment outcomes, but patient experiences are not well understood. Methods. We conducted a qualitative study of patient experiences in decentralized HIV care in Plateau State, north central Nigeria. Five decentralized care sites in the Plateau State Decentralization Initiative were purposefully selected. Ninety-three patients and 16 providers at these sites participated in individual interviews and focus groups. Data collection activities were audio-recorded and transcribed. Transcripts were inductively content analyzed to derive descriptive categories representing patient experiences of decentralized care. Results. Patient participants in this study experienced the transition to decentralized care as a series of "trade-offs." Advantages cited included saving time and money on travel to clinic visits, avoiding dangers on the road, and the "family-like atmosphere" found in some decentralized clinics. Disadvantages were loss of access to ancillary services, reduced opportunities for interaction with providers, and increased risk of disclosure. Participants preferred decentralized services overall. Conclusion. Difficulty and cost of travel remain a fundamental barrier to accessing HIV care outside urban centers, suggesting increased availability of community-based services will be enthusiastically received.

Nasa-wide Standard Administrative Systems

NASA Technical Reports Server (NTRS)

Schneck, P.

1984-01-01

Factors to be considered in developing agency-wide standard administrative systems for NASA include uniformity of hardware and software; centralization vs. decentralization; risk exposure; and models for software development.

Improving urban district heating systems and assessing the efficiency of the energy usage therein

NASA Astrophysics Data System (ADS)

Orlov, M. E.; Sharapov, V. I.

2017-11-01

The report describes issues in connection with improving urban district heating systems from combined heat power plants (CHPs), to propose the ways for improving the reliability and the efficiency of the energy usage (often referred to as “energy efficiency”) in such systems. The main direction of such urban district heating systems improvement suggests transition to combined heating systems that include structural elements of both centralized and decentralized systems. Such systems provide the basic part of thermal power via highly efficient methods for extracting thermal power plants turbines steam, while peak loads are covered by decentralized peak thermal power sources to be mounted at consumers’ locations, with the peak sources being also reserve thermal power sources. The methodology was developed for assessing energy efficiency of the combined district heating systems, implemented as a computer software product capable of comparatively calculating saving on reference fuel for the system.

The school as a force for community change in Tanzania

NASA Astrophysics Data System (ADS)

Maliyamkono, T. L.

1980-09-01

In newly independent countries where traditional theories of educational policy have continued to be followed, education has persisted as little more than a sophisticated mechanism for the recruitment of elites, and there has been an increased dependence on the advanced industrial nations for aid, experts and educational models. Tanzania, however, has attempted to break away from traditional strategies, and the author here describes and analyses the impact of two of the most far-reaching reforms — Education for Self-Reliance, and Decentralization — on national goals and policies. President Nyerere enunciated the objectives for Education for Self-Reliance in 1967 as relating education to rural life, correcting the elitist bias of education, and changing negative attitudes among students towards agriculture and rural life. Five major programmes of reform covering primary and secondary education, teacher and higher education, and examinations were to be pursued, ensuring a closer integration of schools with local communities, e.g., through school farms and co-operative shops, and making curricula directly relevant to local needs. A policy of Decentralization is being implemented, allowing, theoretically at least, a much greater participation at community level in decision-making. In primary and adult education this has already been effected to some extent, though there is evidence to suggest that decentralization in some regions and districts has resulted in the creation of local bureaucratic machinery for control, defeating the intention of the reform. Decentralization of secondary and teacher education is likely to follow, leaving only higher education centrally controlled for manpower training and allocation purposes. Finally the author discusses the question of the transferability of the Tanzanian reforms.

Contribution of Optical Zone Decentration and Pupil Dilation on the Change of Optical Quality After Myopic Photorefractive Keratectomy in a Cat Model

PubMed Central

Bühren, Jens; Yoon, Geunyoung; MacRae, Scott; Huxlin, Krystel

2010-01-01

PURPOSE To simulate the simultaneous contribution of optical zone decentration and pupil dilation on retinal image quality using wavefront error data from a myopic photorefractive keratectomy (PRK) cat model. METHODS Wavefront error differences were obtained from five cat eyes 19±7 weeks (range: 12 to 24 weeks) after spherical myopic PRK for −6.00 diopters (D) (three eyes) and −10.00 D (two eyes). A computer model was used to simulate decentration of a 6-mm sub-aperture relative to the measured wavefront error difference. Changes in image quality (visual Strehl ratio based on the optical transfer function [VSOTF]) were computed for simulated decentrations from 0 to 1500 μm over pupil diameters of 3.5 to 6.0 mm in 0.5-mm steps. For each eye, a bivariate regression model was applied to calculate the simultaneous contribution of pupil dilation and decentration on the pre- to postoperative change of the log VSOTF. RESULTS Pupil diameter and decentration explained up to 95% of the variance of VSOTF change (adjusted R2=0.95). Pupil diameter had a higher impact on VSOTF (median β=−0.88, P<.001) than decentration (median β= −0.45, P<.001). If decentration-induced lower order aberrations were corrected, the impact of decentration further decreased (β= −0.26) compared to the influence of pupil dilation (β= −0.95). CONCLUSIONS Both pupil dilation and decentration of the optical zone affected the change of retinal image quality (VSOTF) after myopic PRK with decentration exerting a lower impact on VSOTF change. Thus, under physiological conditions pupil dilation is likely to have more effect on VSOTF change after PRK than optical zone decentration. PMID:20229950

Contribution of optical zone decentration and pupil dilation on the change of optical quality after myopic photorefractive keratectomy in a cat model.

PubMed

Bühren, Jens; Yoon, Geunyoung; MacRae, Scott; Huxlin, Krystel

2010-03-01

To simulate the simultaneous contribution of optical zone decentration and pupil dilation on retinal image quality using wavefront error data from a myopic photorefractive keratectomy (PRK) cat model. Wavefront error differences were obtained from five cat eyes 19+/-7 weeks (range: 12 to 24 weeks) after spherical myopic PRK for -6.00 diopters (D) (three eyes) and -10.00 D (two eyes). A computer model was used to simulate decentration of a 6-mm sub-aperture relative to the measured wavefront error difference. Changes in image quality (visual Strehl ratio based on the optical transfer function [VSOTF]) were computed for simulated decentrations from 0 to 1500 mum over pupil diameters of 3.5 to 6.0 mm in 0.5-mm steps. For each eye, a bivariate regression model was applied to calculate the simultaneous contribution of pupil dilation and decentration on the pre- to postoperative change of the log VSOTF. Pupil diameter and decentration explained up to 95% of the variance of VSOTF change (adjusted R(2)=0.95). Pupil diameter had a higher impact on VSOTF (median beta=-0.88, P<.001) than decentration (median beta=-0.45, P<.001). If decentration-induced lower order aberrations were corrected, the impact of decentration further decreased (beta=-0.26) compared to the influence of pupil dilation (beta=-0.95). Both pupil dilation and decentration of the optical zone affected the change of retinal image quality (VSOTF) after myopic PRK with decentration exerting a lower impact on VSOTF change. Thus, under physiological conditions pupil dilation is likely to have more effect on VSOTF change after PRK than optical zone decentration. Copyright 2010, SLACK Incorporated.

Does HIV services decentralization protect against the risk of catastrophic health expenditures?: some lessons from Cameroon.

PubMed

Boyer, Sylvie; Abu-Zaineh, Mohammad; Blanche, Jérôme; Loubière, Sandrine; Bonono, Renée-Cécile; Moatti, Jean-Paul; Ventelou, Bruno

2011-12-01

Scaling up antiretroviral treatment (ART) through decentralization of HIV care is increasingly recommended as a strategy toward ensuring equitable access to treatment. However, there have been hitherto few attempts to empirically examine the performance of this policy, and particularly its role in protecting against the risk of catastrophic health expenditures (CHE). This article therefore seeks to assess whether HIV care decentralization has a protective effect against the risk of CHE associated with HIV infection. DATA SOURCE AND STUDY DESIGN: We use primary data from the cross-sectional EVAL-ANRS 12-116 survey, conducted in 2006-2007 among a random sample of 3,151 HIV-infected outpatients followed up in 27 hospitals in Cameroon. DATA COLLECTION AND METHODS: Data collected contain sociodemographic, economic, and clinical information on patients as well as health care supply-related characteristics. We assess the determinants of CHE among the ART-treated patients using a hierarchical logistic model (n = 2,412), designed to adequately investigate the separate effects of patients and supply-related characteristics. Expenditures for HIV care exceed 17 percent of household income for 50 percent of the study population. After adjusting for individual characteristics and technological level, decentralization of HIV services emerges as the main health system factor explaining interclass variance, with a protective effect on the risk of CHE. The findings suggest that HIV care decentralization is likely to enhance equity in access to ART. Decentralization appears, however, to be a necessary but insufficient condition to fully remove the risk of CHE, unless other innovative reforms in health financing are introduced. © Health Research and Educational Trust.

Development of a pharmacy resident rotation to expand decentralized clinical pharmacy services.

PubMed

Hill, John D; Williams, Jonathan P; Barnes, Julie F; Greenlee, Katie M; Cardiology, Bcps-Aq; Leonard, Mandy C

2017-07-15

The development of a pharmacy resident rotation to expand decentralized clinical pharmacy services is described. In an effort to align with the initiatives proposed within the ASHP Practice Advancement Initiative, the department of pharmacy at Cleveland Clinic, a 1,400-bed academic, tertiary acute care medical center in Cleveland, Ohio, established a goal to provide decentralized clinical pharmacy services for 100% of patient care units within the hospital. Patient care units that previously had no decentralized pharmacy services were evaluated to identify opportunities for expansion. Metrics analyzed included number of medication orders verified per hour, number of pharmacy dosing consultations, and number of patient discharge counseling sessions. A pilot study was conducted to assess the feasibility of this service and potential resident learning opportunities. A learning experience description was drafted, and feedback was solicited regarding the development of educational components utilized throughout the rotation. Pharmacists who were providing services to similar patient populations were identified to serve as preceptors. Staff pharmacists were deployed to previously uncovered patient care units, with pharmacy residents providing decentralized services on previously covered areas. A rotating preceptor schedule was developed based on geographic proximity and clinical expertise. An initial postimplementation assessment of this resident-driven service revealed that pharmacy residents provided a comparable level of pharmacy services to that of staff pharmacists. Feedback collected from nurses, physicians, and pharmacy staff also supported residents' ability to operate sufficiently in this role to optimize patient care. A learning experience developed for pharmacy residents in a large medical center enabled the expansion of decentralized clinical services without requiring additional pharmacist full-time equivalents. Copyright © 2017 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Application-Defined Decentralized Access Control

PubMed Central

Xu, Yuanzhong; Dunn, Alan M.; Hofmann, Owen S.; Lee, Michael Z.; Mehdi, Syed Akbar; Witchel, Emmett

2014-01-01

DCAC is a practical OS-level access control system that supports application-defined principals. It allows normal users to perform administrative operations within their privilege, enabling isolation and privilege separation for applications. It does not require centralized policy specification or management, giving applications freedom to manage their principals while the policies are still enforced by the OS. DCAC uses hierarchically-named attributes as a generic framework for user-defined policies such as groups defined by normal users. For both local and networked file systems, its execution time overhead is between 0%–9% on file system microbenchmarks, and under 1% on applications. This paper shows the design and implementation of DCAC, as well as several real-world use cases, including sandboxing applications, enforcing server applications’ security policies, supporting NFS, and authenticating user-defined sub-principals in SSH, all with minimal code changes. PMID:25426493