Order Reference Model Research Articles

Extended fuel swelling models and ultra high burn-up fuel behavior of U–Pu–Zr metallic fuel using FEAST-METAL

Computational models in FEAST-METAL U–Pu–Zr metallic fuel behavior code have been upgraded to improve fission gas, solid fission product swelling, and pore sintering behavior in a microstructure dependent form. First, fission gas bubble growth is modeled by selecting small and large bubble groups according to a fixed number of gas atoms per bubble group. Small bubbles nucleated at phase boundaries grow via gas migration and turn into large bubbles. Furthermore, bubble morphology for each phase structure is captured by selecting the number of atoms per bubble and the shape of the bubbles in a phase dependent form. The gas diffusion coefficients for the single gamma phase and effective dual (α+δ) and (β+γ) phase structures are modeled separately, using the activation energy of the corresponding phase structure. In this study, it is found that pressure sintering of the interconnected porosity in dual phases should be less effective than the reference model in order to match clad strain and fission gas release behavior. In addition to these improvements, a probabilistic approach is taken to verify the fission gas-swelling threshold at which interconnected porosity begins. This fracture problem is treated as a function of critical crack length formed via bubble coalescence. It was found that a 10% gas-swelling threshold is appropriate for a wide range of gas bubble sizes. The new version of FEAST-METAL predicts the burn-up, smear density, and axial variation of the clad hoop strain and fission gas release behavior satisfactorily for selected test pins under EBR-II conditions. The code is used to predict ultra-high burn-up U–Pu–6Zr vented metallic fuel behavior with HT9 cladding for fast breeder reactor applications for 20 years of irradiation. It is assumed that HT9 clad will retain its fracture toughness and creep properties for this simulation. It appears that the increased dose on the cladding, increased solid fission product swelling, and low operating fuel temperature requires lower fuel smear density (∼60%) in order to ensure acceptable clad hoop strain at high burn-up (∼35at.%). Furthermore, keeping the peak clad temperature below 550°C seems to control lanthanide migration and clad inner wastage at a reasonable level. Possible design concerns and improvements are discussed.

Optimal adaptive design of the prescribed-structure controllers

For the continuous linear control plants with parametric uncertainty, a new approach to the H2-design of multivariable controllers of the prescribed structure was suggested. For the desired reference model of the control system of full and low order, the property of adaptability of such control systems was defined, and the criteria for adaptability in terms of matrices and adaptability gramians were formulated. The structural properties of the matrices and adaptability gramians were analyzed, and their relation to the matrices and the gramians of controllability and observability were established. A new approach to the parametric controller optimization with the use of adaptability gramians was proposed. The integral estimates of the degree of deviation of the performance indices of the stationary continuous control systems with a prescribed-structure controller and the parametric uncertainty of the interval-type plant from the performance indices of the desired reference model of full and low order were obtained.

Classical controller design techniques for fractional order case

This paper presents some classical controller design techniques for the fractional order case. New robust lag, lag-lead, PI controller design methods for control systems with a fractional order interval transfer function (FOITF) are proposed using classical design methods with the Bode envelopes of the FOITF. These controllers satisfy the robust performance specifications of the fractional order interval plant. In order to design a classical PID controller, an optimization technique based on fractional order reference model is used. PID controller parameters are obtained using the least squares optimization method. Different PID controller parameters that satisfy stability have been obtained for the same plant.

New Integrated Information System for Pusan National University Hospital

ObjectivesThis study presents the information system for Pusan National University Hospital (PNUH), evaluates its performance qualitatively, and conducts economic analysis.MethodsInformation system for PNUH was designed by component-based development and developed by internet technologies. Order Communication System, Electronic Medical Record, and Clinical Decision Support System were newly developed. The performance of the hospital information system was qualitatively evaluated based on the performance reference model in order to identify problem areas for the old system. The Information Economics approach was used to analyze the economic feasibility of hospital information system in order to account for the intangible benefits.ResultsAverage performance scores were 3.16 for input layer, 3.35 for process layer, and 3.57 for business layer. In addition, the cumulative benefit to cost ratio was 0.50 in 2011, 1.73 in 2012, 1.76 in 2013, 1.71 in 2014, and 1.71 in 2015. The B/C ratios steadily increase as value items are added.ConclusionsWhile overall performance scores were reasonably high, doctors were less satisfied with the system, perhaps due to the weak clinical function in the systems. The information economics analysis demonstrated the economic profitability of the information systems if all intangible benefits were included. The second qualitative evaluation survey and economic analysis were proposed to evaluate the changes in performance of the new system.

Reference models in the electronic library

PurposeThis study aims to describe reference service activity within a learning commons at a large research university. The researchers tested several reference models in order to explore new ways of providing research support to their patrons within the electronic library. The aim was to discover student responses to different models and to investigate patron need of, and desire for, research support at the learning commons.Design/methodology/approachThe researchers combined measurements of type and frequency of reference traffic both in person and through their online chat reference service. They also gathered quantitative and qualitative information during the reference model experiments and through a survey of patrons in order to discover patron use of, and thoughts concerning, reference service in the electronic library.FindingsResults from reference model experiments and a survey of patrons show that there is indeed an audience for research assistance in the electronic library and that in‐person research support is the preferred method of service. To keep pace with student needs, the researchers will continue to experiment with reference models that support in‐person research assistance beyond the traditional reference desk.Practical implicationsThe researchers provide examples and guidelines for introducing new reference services in a learning commons environment and suggest ideas for further experimentation with reference models in a predominantly electronic environment.Originality/valueThe results of this study will be of interest to academic librarians, especially those who have or are planning a learning commons. This research is also of interest to those studying student research behavior and attitudes towards library collections and services. Because this learning commons is a unique environment as a stand‐alone electronic library, computing, and classroom space, this study makes an original contribution to the literature. As planners of learning commons explore models that move away from the traditional library, this study will inform the possible implications of new designs for reference service.

How much do we gain by introducing route optimization in Proxy Mobile IPv6 networks?

Proxy Mobile IPv6 has been developed from the concept of network-based mobility support protocol in the Internet Engineering Task Force. The recently published specification of Proxy Mobile IPv6 only focuses on the mobility support without a mobile host’s participation in the mobility signaling. Then, route optimization issues are left in the basket for further works. In this paper, we explore the existing route optimization proposals that are analyzed and matched against a list of functional and operational angles. Then, the chosen two route optimization proposals are evaluated in terms of signaling cost, packet delivery cost, total cost, and service blocking probability. Through the provided analysis results, we demonstrate that route optimization solves the ineffective routing path problem when the mobile host communicates with its corresponding host and argue that the scalability of Proxy Mobile IPv6 architecture is also improved due to the distributed routing path. In addition, the cost model developed in this paper would be a reference model in order to facilitate decision making for further route optimization design.

Towards an objective evaluation of tolerances for beam modeling in a treatment planning system

The performance of a convolution/superposition based treatment planning system depends on the ability of the dose calculation algorithm to accurately account for physical interactions taking place in the tissue, key components of the linac head and on the accuracy of the photon beam model. Generally the user has little or no control over the performance of the dose calculation algorithm but is responsible for the accuracy of the beam model within the constraints imposed by the system. This study explores the dosimetric impact of limitations in photon beam modeling accuracy on complex 3D clinical treatment plans. A total of 70 photon beam models was created in the Pinnacle™ treatment planning system. Two of the models served as references for 6 MV and 15 MV beams, while the rest were created by perturbing the reference models in order to produce specific deviations in specific regions of the calculated dose profiles (central axis and transverse). The beam models were then used to generate 3D plans on seven CT data sets each for four different treatment sites (breast and conformal prostate, lung and brain). The equivalent uniform doses (EUD) of the targets and the principal organs at risk (OARs) of all plans (∼1000) were calculated and compared to the EUDs delivered by the reference beam models. In general, accurate dosimetry of the target is most greatly compromised by poor modeling of the central axis depth dose and the horns, while the EUDs of the OARs exhibited the greatest sensitivity to beam width accuracy. Based on the results of this analysis we suggest a set of tolerances to be met during commissioning of the beam models in a treatment planning system that are consistent in terms of clinical outcomes as predicted by the EUD.

Tuning the dynamic behaviour of cantilever MEMS based sensors and actuators

PurposeThis paper seeks to establish an analytical reference model in order to optimize the frequency response of MEMS cantilever structures using cutouts.Design/methodology/approachPresented in this work is a method to tune the frequency response of MEMS cantilevers by using single cutouts of various sizes. From an interpretation of the analytical results, mass and stiffness domains are defined as a function of the cutout position on the cantilever. In this regard, the elastic properties of the MEMS cantilever can be trimmed through mechanical tuning by a single cutout incorporated into the device geometry. The Rayleigh‐Ritz energy method is used for the modeling. Analytical results are compared with FEM and experimental results.FindingsThe eigenvalues are dependent on the position and size of the cutout. Hence, the frequency response of the cantilever can be tuned and optimized through this approach.Research limitations/implicationsMEMS microsystems are sensitive to microfabrication limitations especially at the boundary support of suspended structures such as microcantilevers.Practical implicationsMEMS cantilevers are resistant to low level vibrations due to their low inertia and the elastic properties of the silicon material. For sensor applications these qualities are highly regarded and explored. This analysis will contribute to the performance optimization of atomic force microscope (AFM) probes and micromechanical resonators.Originality/valueA method to tune, with cutouts, the frequency response of microcantilevers is proposed. The data can provide insight into the performance optimization of micromechanical resonators through mass reduction. For industrial applications requiring optimized responses the cutouts can be incorporated into microcantilevers through focused ion beam (FIB) machining or laser drilling, for example.

Application of Fuzzy Gain-Scheduling in Position Control of a Servo Hydraulic System with a Flexible Load

AbstractThe control of hydraulic servo-systems has been the focus of intense research over the past decades. Hydraulic position servos with an asymmetrical cylinder are commonly used in industry. These kinds of systems are nonlinear in nature and generally difficult to control. Changing system parameters using the same gains will cause overshoot or even loss of system stability. The highly non-linear behaviour of these devices makes them ideal subjects for applying different types of sophisticated controllers. The paper is concerned with a second order model reference to positioning control of a flexible load servo-hydraulic system using fuzzy gain-scheduling. In the present study, to compensate the lack of damping in a hydraulic system, an acceleration feedback was used. To compare the results, a p-controller with feedforward acceleration and different gains in extension and retraction is used. The design procedure for the controller and experimental results are discussed. The results suggest that using ...

05/01162 Test of a small domestic boiler using different pellets

The aim of this paper is to present and evaluate control strategies for adjustment and preservation of air quality, thermal and visual comfort for buildings’ occupants while, simultaneously, energy consumption reduction is achieved. Fuzzy PID, fuzzy PD and adaptive fuzzy PD control methods are applied. The inputs to any controller are: the PMV index affecting thermal comfort, the CO2 concentration affecting indoor air quality and the illuminance level affecting visual comfort. The adaptive fuzzy PD controller adapts the inputs and outputs scaling factors and is based on a second order reference model. More specifically, the scaling factors are modified according to a sigmoid type function, in such a way that the measured variable to be as closer as possible to the reference model. The adaptive fuzzy PD controller is compared to a non-adaptive fuzzy PD and to an ON–OFF one. The comparison criteria are the energy required and the controlled variables response. Both, energy consumption and variables responses are improved if the adaptive fuzzy PD type controller is used. The buildings’ response to the control signals has been simulated using MATLAB/SIMULINK.

Adaptive filter design for image deblurring by using multi-criteria blurred image information

This paper introduces a novel method to enhance the quality of blurred images. The proposed method is based on the estimation of the multi-criteria information of the degraded images. The multi-criteria information is extracted from the distribution model and the boundaries of the input image. The actual image blurred by an unknown distribution is correlated with predetermined reference models in order to choose the restoration filter model. The filter coefficient is then estimated using the edge information of the degraded image. Experiments have been conducted using simulated and real world images to evaluate the performance of the proposed method and the results are presented.

Using Fractional Order Adjustment Rules and Fractional Order Reference Models in Model-Reference Adaptive Control

This paper investigates the use of Fractional Order Calculus (FOC) inconventional Model Reference Adaptive Control (MRAC) systems. Twomodifications to the conventional MRAC are presented, i.e., the use offractional order parameter adjustment rule and the employment offractional order reference model. Through examples, benefits from theuse of FOC are illustrated together with some remarks for furtherresearch.

Reduced spatial order model reference adaptive control of spatially varying distributed parameter systems of parabolic and hyperbolic types

AbstractThis paper presents control laws for distributed parameter systems of parabolic and hyperbolic types with unknown spatially varying parameters. These laws, based on the model reference adaptive control approach, guarantee asymptotic tracking of the output of the reference model by the output of the plant for arbitrary time invariant, but spatially varying reference input. The novel capabilities of the algorithms proposed are providing reduced sensitivity to measurement noise due to the reduced order of the spatial differentiation of the output data and permitting on‐line estimation of the spatially varying plant parameters, constructively enforceable through the reference input and/or boundary conditions. The parameter estimation is carried out by means of an auxiliary system with the time‐varying parameters that simultaneously converge in L2 to plant parameters when appropriate input signals in the reference model are used. The orthogonal expansions of these time‐varying parameters, which can be computed by passing the auxiliary system parameters through the integrator block, converge to the plant parameters pointwise if the latter are sufficiently smooth. The parameter convergence is obtained by combining the adaptation laws with sufficiently rich input signals, referred to as generators of persistent excitation, which guarantee the existence of a unique steady state for the parameter errors. Copyright © 2001 John Wiley & Sons, Ltd.

The application of UML and an open distributed process framework to information system design

The development of information systems to support design and manufacturing activities should follow a reference model in order to be compatible with major systems architectures. In contrast, computational methodologies and notations provide ways to design and build information systems but usually do not take reference models into consideration. This paper discusses how reference models and computational methodologies/notation can be used in harmony, and demonstrates this through an example of an information system design where Unified Modelling Language (UML) diagrams are applied to represent the Reference Model of Open Distributed Processing (RM-ODP) viewpoints. A selected set of UML diagrams has been applied in the Enterprise, Information and Computational RM-ODP viewpoint. The inherent object-oriented properties of the reported research further enable and facilitate the migration of essential elements from one RM-ODP viewpoint to another via the use of UML notation. This approach provides an important contribution by harmonising a range of views of an information system.

Advanced fuzzy logic controllers design and evaluation for buildings’ occupants thermal–visual comfort and indoor air quality satisfaction

The aim of this paper is to present and evaluate control strategies for adjustment and preservation of air quality, thermal and visual comfort for buildings’ occupants while, simultaneously, energy consumption reduction is achieved. Fuzzy PID, fuzzy PD and adaptive fuzzy PD control methods are applied. The inputs to any controller are: the PMV index affecting thermal comfort, the CO 2 concentration affecting indoor air quality and the illuminance level affecting visual comfort. The adaptive fuzzy PD controller adapts the inputs and outputs scaling factors and is based on a second order reference model. More specifically, the scaling factors are modified according to a sigmoid type function, in such a way that the measured variable to be as closer as possible to the reference model. The adaptive fuzzy PD controller is compared to a non-adaptive fuzzy PD and to an ON–OFF one. The comparison criteria are the energy required and the controlled variables response. Both, energy consumption and variables responses are improved if the adaptive fuzzy PD type controller is used. The buildings’ response to the control signals has been simulated using MATLAB/SIMULINK.

Direct tip regulation of a single-link flexible manipulator by adaptive variable structure control

Direct tip position regulation of flexible manipulators is one of the most challenging control tasks. There are mainly three problems to be addressed in order to achieve good performance. The first two control problems arise owing to the unstable zeros and complex poles in the system nominal part which is dominated by a transfer function. The third problem is the existence of unstructured uncertainties owing to the truncation of high-order resonance modes and system nonlinearities. Because of the above difficulties and in particular the non-minimum-phase nature, tip regulation task of flexible manipulators is usually solved indirectly: direct control of joint angle and suppression of the flexible link vibration. The aim of this study is to investigate the direct approach for tip regulation. Since the tip transfer function contains unstable zeros and the first few dominant flexible modes (complex poles), a reference model of the same order is selected which does not have any finite zero but all negative re...

Direct tip regulation of a single-link flexible manipulator by adaptive variable structure control

Direct tip position regulation of flexible manipulators is one of the most challenging control tasks. There are mainly three problems to be addressed in order to achieve good performance. The first two control problems arise owing to the unstable zeros and complex poles in the system nominal part which is dominated by a transfer function. The third problem is the existence of unstructured uncertainties owing to the truncation of high-order resonance modes and system nonlinearities. Because of the above difficulties and in particular the non-minimum-phase nature, tip regulation task of flexible manipulators is usually solved indirectly: direct control of joint angle and suppression of the flexible link vibration. The aim of this study is to investigate the direct approach for tip regulation. Since the tip transfer function contains unstable zeros and the first few dominant flexible modes (complex poles), a reference model of the same order is selected which does not have any finite zero but all negative real poles. In order to force the system to follow the reference model in the presence of the unstructured uncertainties, a variable structure controller is adopted in which the switching surface is derived from the reference model. When in sliding mode, the system performs as the reference model. Hence there will be no vibration and the tip position regulation can be achieved when the system approaches steady state. To improve the system responses further, an adaptation law with dead-zone scheme is combined with the variable structure controller. Simulation results show that link vibrations have been eliminated and the control profile is fairly smooth.

Multirate Predictive Control with Nonlinear Optimization Application to a Thermal Process for Batch Dyeing

In this paper, we present a new approach to multirate predictive control with a multiple reference model in order to control commercial processes with nonlinear models, such as batch dyeing thermal processes. The time delay problem is resolved successfully by using multirate predictive control, and we introduce nonlinear optimization based on an augmented Lagrangien objective function to minimize the multirate predictive control quadratic criterion in the case of the nonlinear plant model. Moreover, the multirate approach improves predictive control robustness. The results of our study are used to simulate nonlinear thermal plant control with very good results. For this reason, our future work will use this method to control a batch dyeing process.

A formal description of open distributed processing (ODP) trading based on guidelines for the definition of managed objects (GDMO)

New requirements of growing computer networks and information systems have an influence on extended client/server models with increased functionality. This forms the basis for service management in distributed systems which is realized by a service trading concept. This paper studies the requirements derived from the Open Distributed Processing (ODP) Reference Model in order to consider an open service market. Furthermore, it examines management possibilities for describing the service trading scenario. Because of similar architectures and properties ODP services, service offers, types, exporters and traders are mapped onto management components and modeled as managed objects. Therefore, the Guidelines for the Definition of Managed Objects (GDMO) are used. The final concept allows a precise and unambiguous study of the service trading scenario and provides means for exporting and importing of service offers in a distributed environment.

Multimedia communication systems: upper layers in the OSI reference model

The structuring, services, and major protocol functions that are required in the upper layers of the OSI reference model in order to support end-to-end multimedia communication, assuming a simple transport service, are examined. It is assumed that variable-bit-rate (VBR) coding techniques will be used in future multimedia systems. Mutual stream synchronization, integral management, and multiparty connections, which appear to be crucial issues in multimedia communication, are addressed. Important implementation and performance issues are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>