Adaptive Integration Research Articles

Online dynamic optimization studies of autocatalytic esterification in the semi batch reactor for handling disturbance and uncertainty

A Catalyzed Esterification of Propionic Anhydride with 2-Butanol in the semi batch reactor which involves complex pathways of the autocatalytic mechanism, is producing sec-butyl propionate and propionic acid. An online dynamic-cascaded based optimization is an effective way to handle the effect uncertainty and disturbance within semi batch process. The re-optimization and control problems are solved separately in two layers. The online optimization strategy includes an integration of dynamic re-optimizer, i.e. orthogonal collocation (OC) method in maximizing profit, estimator, i.e. Cubature Kalman Filter and controller, i.e. adaptive Proportional Integrator Derivative (PID). The re-optimization mechanism is activated conditionally by using simple trigger, i.e. ±5% of conversion as active constraint. The simulation results show that the proposed strategy offers a large improvement of reactor's performance in handling uncertainty and disturbance where re-optimized temperature and feed flowrate trajectories obtained able to keep the conversion within acceptable range (on-spec).

An adaptive integration scheme for heat conduction in additive manufacturing

Abstract Solidification dynamics are important for determining final microstructure in additively manufactured parts. Recently, researchers have adopted semi-analytical approaches for predicting heat conduction effects at length and time scales not accessible to complex multi-physics numerical models. The present work focuses on improving a semi-analytical heat conduction model for additive manufacturing by designing an adaptive integration technique. The proposed scheme considers material properties, process conditions, and the inherent physical behavior of the transient heat conduction around both stationary and moving heat sources. Both the adaptive integration scheme and a technique for calculating only the points within the melt pools are described in detail. The full algorithm is then implemented and compared against a simple Riemann sum integration scheme for a variety of cases that highlight process and material variations relevant to additive manufacturing. The new scheme is shown to have significant improvements in computational efficiency, solution accuracy, and usability.

Psychological adaptation among second-generation Moroccan adolescents: associations with sense of community and country of residence

ABSTRACT Increasing evidence suggests that immigrant youths’ social integration varies widely across national contexts, but the factors explaining this variation at the individual and societal levels are still under debate. Drawing upon developmental and community psychology approaches, the current study aimed to investigate psychological adaptation in terms of life satisfaction, self-esteem, and psychological problems among second-generation Moroccan adolescents and their national peers in the Netherlands and Italy. Furthermore, we examined the role of sense of community (SoC) in these youths’ outcomes. Participants were 90 Moroccan-origin and 208 national adolescents aged between 17 and 20 years, who completed a questionnaire survey. Results indicated that life satisfaction was overall higher in the Netherlands than in Italy. Moreover, Moroccan and Dutch youth reported similar levels of self-esteem and psychological problems, whereas Italian youths fared less well than their Moroccan peers. The positive association between SoC and life satisfaction was stronger for Moroccan adolescents in both countries; SoC was related to higher self-esteem and fewer psychological problems, but only in Italy. The findings suggest that characteristics of the host society are crucial for the psychological adjustment of second-generation Moroccan adolescents, and that programs targeting SoC may boost these youths’ positive adaptation and social integration.

Integral Accuracy and the Stability of Two Methods for the Solution of Time-Domain Integral Equations for Scattering From Perfect Conductors

The stability of time-domain (TD) integral equation (TDIE) approaches to the computation of electromagnetic scattering is profoundly affected by the accuracy of the underlying numerical integration methods used for computation of the kernel elements. In most publications, the accuracy of the quadratures used to compute kernel elements is never measured, and higher order computation is assumed to deliver high accuracy. In this communication, we examine the complicated relationship between the actual accuracy of kernel element computation and the resulting stability of integral equations. The numerical results show that stability may be improved for higher integral accuracy. Although integral accuracy is not always improved by higher order integration rules, more careful integration (as delivered by adaptive integration methods) is often helpful. The numerical results for a range of problems demonstrate these contentions.

Robust and computationally efficient online image stabilisation framework based on adaptive dual motion vector integration

Image stabilisation aims to compensate and smoothen the effects of undesired trembling motion of cameras mounted on non‐static platforms. It becomes quite a challenging task in the case of moving platforms, such as ground vehicles, unmanned aerial vehicles, and handheld devices. Many satisfactory solutions to the image stabilisation problem are proposed in the recent literature, but most of these methods are not adaptable for handling a wide range of intentional motions with minimum lag, especially in real‐time scenarios. In this study, the authors propose an online two‐dimensional image stabilisation technique based on dual motion vector integration, which is a novel adaptive motion smoothing technique that employs an average length of motion vectors to estimate the intentional motion. The overall computational cost of the proposed system is significantly reduced by employing frame‐shaking judgment that only allows processing of jittering frames. Promising experimental results have been obtained on challenging videos obtained from hand‐held and vehicle‐mounted cameras which demonstrate the robustness and effectiveness of the proposed technique against feature point mismatching and presence of moving objects within the scene at a frame rate of 30 frames per second.

A velocity-free adaptive RISE-based trajectory tracking approach for quadrotors with desired model compensation

This paper presents a velocity-free desired compensation trajectory tracking strategy integrated with adaptive robust integral of the sign of the error (RISE) feedback mechanism for quadrotors concerning parametric uncertainties and external disturbances. The original cascaded dynamics of quadrotor is derived in a strict form with additive disturbances. Then, the adaptive RISE feedback controllers are respectively constructed in position and attitude loop, in which the control gains in RISE terms are adaptively updated online to ensure the robustness against uncertainties. In addition, to alleviate the measurement noise effect arising from the actual velocity signals, the velocity states in the model-based feedforward control are replaced with their desired values, then the desired compensation adaptive RISE controllers that depend on the desired trajectory and output tracking errors are synthesized, where the design conservatism on selecting the control gain in RISE is eliminated without knowing the prior bound of uncertainties, and enhanced performance robustness is also retained in the absence of velocity information. It is shown via Lyapunov analysis that the proposed method can guarantee the tracking errors to converge to the origin with asymptotic performance despite of bounded disturbances. The effectiveness and superiority of proposed method are validated through extensive simulations and comparisons.

Analyzing coastal coupled infrastructure systems through multi-scale serious games in Languedoc, France

In the context of global change, the South of Gard coastal region in southern France is building up an adaptation plan in order to reduce vulnerability to several external drivers, including demographic growth, sea rise, and a new environmental directive from the European Union. However, adaptations which would reduce the vulnerability of some stakeholders might increase that of others. To explore transfers of vulnerability and their consequences with local stakeholders, we designed a serious game where players take the roles of sectoral planners in different places and on different scales of the territory. We organized a game session with 50 elected people and experts coming from various sectors. This experiment showed that adaptations on the local regional scale make it possible to cope temporarily with the pressures of global change by transferring these pressures to other sub-regions, other sectors, or even other scales. Analyzing the game session, we observed four categories of vulnerability transfers: transfers that were prevented by anticipation, transfers that were prevented by chance (non-purposely), transfers that were limited by a reaction (a posteriori), and transfers that simply occurred. Transfers prevented by anticipation required complex integration of local and sectoral adaptations. Urban growth linked to strategic retreat adaptations, which was identified as the major pressure, could be partly dealt with by trade-offs involving negotiations between several sectors in several places and at several scales.

Good will hunting: social integration of students receiving forgivable loans for college education in contexts of high inequality

ABSTRACT This article explores the black box of college adaptation and social integration of low SES students entering higher education under a forgivable loans program. It does so by studying a context of extreme educational and economic inequality. The magnitude of this study offers an unprecedented window to observe interactions between different social classes in college. Drawing on two different fieldworks, this study is based on 19 focal groups in 8 cities and 12 universities, and in an in-depth study of one elite university. Results show that low SES students actively mobilize different types of personal resources to integrate to the college environment, but they face strong objective and symbolic barriers. Results show also that regular students, on occasion, act as cultural guides for low SES students, helping them in the process of college adaption, and that colleges’ characteristics and diversity influence beneficiaries’ social integration and well-being.

An enhanced transient solver with dynamic p‐adaptation and multirate time integration for electromagnetic and multiphysics simulations

AbstractThis paper presents an enhanced discontinuous Galerkin time‐domain (DGTD) solver for the simulation of both pure electromagnetic (EM) and multiphysics problems. By exploring the local variation of the physics, the polynomial expansion order of the physical quantity of interest is allowed to be adjusted locally and dynamically during the real time of a simulation, leading to a dynamic p‐adaptation technique that can provide a sufficient spatial resolution whenever and wherever needed while keeping the computational cost low. On top of the dynamic adaptation, the constraint of the time step size by an explicit time integration method is alleviated through the application of a multirate time integration (MTI) technique, which permits different time step sizes in elements with different sizes and polynomial orders. Together with the dynamic adaptation and MTI techniques, the enhanced DGTD method is both accurate and efficient in space and time and is employed in the numerical investigations of EM and multiphysics problems to demonstrate its performance and application.

A Metaheuristic Adaptive Cubature Based Algorithm to Find Bayesian Optimal Designs for Nonlinear Models

Finding Bayesian optimal designs for nonlinear models is a difficult task because the optimality criterion typically requires us to evaluate complex integrals before we perform a constrained optimization. We propose a hybridized method where we combine an adaptive multidimensional integration algorithm and a metaheuristic algorithm called imperialist competitive algorithm to find Bayesian optimal designs. We apply our numerical method to a few challenging design problems to demonstrate its efficiency. They include finding D-optimal designs for an item response model commonly used in education, Bayesian optimal designs for survival models, and Bayesian optimal designs for a four-parameter sigmoid Emax dose response model. Supplementary materials for this article are available online and they contain an R package for implementing the proposed algorithm and codes for reproducing all the results in this article.

Power Control of Virtual Oscillator Controlled Inverters in Grid-Connected Mode

This paper proposes a novel method to determine and control active and reactive power output of the virtual ocillator control-based inverter in grid-connected mode. An analytical expression is introduced to describe the quasi-steady-state relationship between the parameters of the inverter including its controllers, and the power injection and voltage at the inverter terminals. We introduce a new, complex valued parameter ( K ) to the conventional virtual oscillator control (VOC) scheme in order to control the inverter output power. We compare analytic and numeric solutions of the above analytical expression with time-domain simulation results, using different K values and line impedances to validate the analytical expression. In the second part of the paper, we design a controller: we use the above expression to derive K for given reference powers and use adaptive integrators to compensate for the remaining errors. We compare this control scheme to a method that uses PI controllers, and also to a simple decoupling method for independent control of active and reactive power. The controller based on the analytical method exhibits very good dynamic and decoupling performance. A single VOC-controlled inverter connected to a nonstiff grid is simulated in MATLAB/Simulink for demonstration, and is also validated using real-time simulations.

An Adaptive Step Implicit Midpoint Rule for the Time Integration of Newton\u2019s Linearisations of Non-Linear Problems with Applications in Micromagnetics

The implicit mid-point rule is a Runge–Kutta numerical integrator for the solution of initial value problems, which possesses important properties that are relevant in micromagnetic simulations based on the Landau–Lifshitz–Gilbert equation, because it conserves the magnetization length and accurately reproduces the energy balance (i.e. preserves the geometric properties of the solution). We present an adaptive step size version of the integrator by introducing a suitable local truncation error estimator in the context of a predictor-corrector scheme. We demonstrate on a number of relevant examples that the selected step sizes in the adaptive algorithm are comparable to the widely used adaptive second-order integrators, such as the backward differentiation formula (BDF2) and the trapezoidal rule. The proposed algorithm is suitable for a wider class of non-linear problems, which are linearised by Newton’s method and require the preservation of geometric properties in the numerical solution.

Commodification of forestlands and assault on indigenous knowledge within forest-dependent communities of Cross River State, Nigeria

The basic component of any society’s knowledge system is undoubtedly its indigenous knowledge. This consists of skills, experiences and insights which the people apply to maintain and improve their lives. Indigenous patterns of behaviour are well known for not only being relevant for preserving local forest resources but also for enriching livelihood systems. Adopting participatory rural appraisal research methods consisting of transects, trend analyses, seasonal calendars, institutional analyses and direct observations, this paper discusses how increased privatisation of forestlands and resources within forest-dependent communities of Cross River, Nigeria is evolving into well-developed alienating structures of neoliberal markets, thereby incapacitating local populations in adapting to environmental changes and resulting stressors of extreme events. This issue is also complicated by their cultural ability to tackle challenges of external adaptation and internal integration that confront them. Hence, actions and policies of forest conservation within forest-dependent communities of Cross River need to be more directed at promoting indigenous knowledge systems that brace common meaning for forests. Indigenous educational systems should also be strengthened in ways that help community people begin to think historically about alternative outcomes, and how they are agents and victims of history and their forestlands and resources are no longer for the public good.

A decomposition–integration model with dynamic fuzzy reconstruction for crude oil price prediction and the implications for sustainable development

Grasping the future fluctuation characteristics and trend of oil prices form the basis for a deep understanding of the system mechanisms and development trends of related research fields. However, due to the complex features of the oil price, accurate prediction is very difficult to get. In order to improve the accuracy of international crude oil price predictions, a novel hybrid prediction model is proposed, that is improved on existing decomposition ensemble learning techniques by developing the Dynamic Time Warping Fuzzy Clustering method (FCM-DTW) as a new reconstruction rule. The hybrid model consists of four main steps. First, the West Texas Intermediate (WTI) crude oil spot price is decomposed into a series of relatively stable, different frequency eigenmode components (IMFs) using the adaptive noise complete integration empirical mode decomposition algorithm (CEEMDAN). FCM-DTW is then employed to reconstitute the IMFs into three sub-sequences. Subsequently, an Autoregressive Integrated Moving Average (ARIMA) model is selected according to the data characteristics of the reconstructed sequence and applied to predict the reconstructed components. Finally, a simple additive method is used to integrate the predicted results of each reconstructed component to generate the crude oil price prediction value. The results show that the prediction accuracy of the proposed hybrid model, based on dynamic time warping fuzzy clustering algorithm, is significantly better than the benchmarks considered in this paper.

Integration of Genotype, Physiological Performance, and Survival in a Lizard (Uta stansburiana) with Alternative Mating Strategies.

Covariation among behavioral and physiological traits is thought to enhance reproductive success and Darwinian fitness. Species that exhibit alternative mating strategies provide excellent opportunities to assess the relative contributions of physiological and behavioral traits to fitness. Male side-blotched lizards (Uta stansburiana) exhibit three heritable throat color morphs that are associated with alternative mating behaviors. The three morphs differ in resource holding potential, mate attraction, mate defense, and physiological performance. We examined interrelationships of body mass, stamina, field metabolic rate, growth rate, and survival to the second capture (a fitness proxy). Relationships among variables were complex, and mass, stamina, and throat color interacted to predict male survival. Our analyses suggest that male side-blotched lizards exhibit trade-offs among physiological traits related to reproductive success and survival and that differential survival for different combinations of traits has caused correlational selection, leading to adaptive integration of phenotypic traits associated with alternative mating strategies.

Organizational Culture in Healthcare Services: Characteristics, Advantages and Disadvantages

Organizational culture - a system of rules, values and behaviors of an organization's – is a key factor of the functionality, performance and quality of the services it provides. Organizational culture is the personality of the organization. It is a structured set of key assumptions that have been invented, discovered or developed by a team of the organization in order to cope with problems of external adaptation or internal integration. Organizational culture creates a sense of identity for every health formation, while it is serving as a reference frame for decisions and actions. The purpose of this review is to present the conceptual framework of organizational culture in the light of its existence in health organizations. Additionally, the development of its special characteristics as well as its positive and/ or negative contribution (advantages and disadvantages) to the way the health services operate are examined. Organizational culture is characterized by difficulty in identifying its components in regards to every environment, it is facing resistance in change and needs time to be implemented.

Analytical framework to evaluate the level of integration of climate adaptation and mitigation in cities

Reduction of carbon emissions and climate-resilience in cities are becoming important objectives to be achieved in order to ensure sustainable urban development pathways. Traditionally, cities have treated climate mitigation and adaptation strategies in isolation, without addressing their potential synergies, conflicts or trade-offs. Recent studies have shown that this can lead to inefficiencies in urban planning, conflicting policy objectives and lost opportunities for synergistic actions. However, in the last few years, we have observed that cities are increasingly moving towards addressing both mitigation and adaptation in urban planning. Cities need to pay particular attention and understand the rationale of both policy objectives whilst considering the integration of the two policies in urban planning and decision-making. This study presents an analytical framework to evaluate the level of integration of climate mitigation and adaptation in cities’ local climate action plans. We tested this framework in nine selected major cities, representatives from all inhabited continents, which are frontrunners in climate action both in their regions and globally. We applied the framework in order to evaluate the level of mitigation and adaptation integration in cities’ CCAPs and further explored the different types of mitigation—adaptation interrelationships that have been considered. A scoring system was also devised in order to allow comparing and ranking of the different CCAPs for their level of integration of adaptation and mitigation. The paper draws good practices to support cities in developing climate change action plans in an integrated way.

A New Adaptive Approach to Control Circulating and Output Current of Modular Multilevel Converter

This paper addresses the output current and circulating current control of the modular multi-level converter (MMC). The challenging task of MMCs is the control of output current and circulating current. Existing control structures for output and circulating current achieve control objectives with comparatively complex controllers and the designed parameters for the controller is also difficult. In this paper, an adaptive proportional integral (API) controller is designed to control the output current and the circulating current. The output current is regulated in α β axes while the circulating current is regulated in the a b c stationary frame to enhance MMC performance. The output and circulating current control results using an API controller are compared with the conventional proportional resonant (PR) controller in terms of transient response, stability, optimal performance, and reference tracking for results verification. The API control architecture significantly improve transient response, stability, and have excellent reference tracking capability. Moreover, it controls output current and converges the circulating current to a desired value. The control structure is designed for a three-phase MMC system, simulated and analyzed in MATLAB-Simulink.

An adaptive PI control scheme to balance the neutral-point voltage in a solar PV fed grid connected neutral point clamped inverter

In the context of current harmonics mitigation in inverter, neutral point clamped (NPC) inverter is the promising one because of its robustness. Owing to the advantages of NPC inverter, this paper considers a PV fed grid connected NPC inverter. However, the main concern with the NPC inverter is the unbalance in the DC link capacitor voltage due to non-idealities such as DC offset in modulating signals, dissimilarities in the DC link capacitors and asymmetric gating signals, which lead to non-zero neutral point voltage. To address this issue, this paper proposes a simple adaptive proportional integral (API) controller and operates in conjunction with the dq axes power controller for PV fed Grid connected NPC inverter. Comprehensive mathematical expressions are derived for the design of API controller and the control parameters are adjusted continuously based on maximum PV power, PV voltage and modulation index for achieving the faster dynamic response. The closed loop stability of the proposed API controller is verified under the deviation in neutral point voltage using root locus plot. The effectiveness of the API with dq axes power controller is analysed and validated through MATLAB simulations and experimentation under the various dynamic operation of the PV- grid interactive system.

Adaptive filter-FLC integration for torque ripples minimization in PMSM using PSO

The article presents torque and flux ripples minimization based on adaptive filter. The adaptive filter coefficients optimized and adapted on line by using particle swarm optimization (PSO) technique. The proposed methodology applied on closed loop speed control based on direct torque control (DTC) for surface mounted permanent magnet synchronous motor (PMSM). Fuzzy logic controller (FLC) used as speed controller while proportional-integral (PI) controller used as torque and flux controllers. Second order infinite impulse response (IIR) filter is used for ripple reduction generated due to FLC. The drive system modeled using Matlab/Simulink software in order to dynamically evaluate the performance of the proposed drive system at different operating conditions. The results provide evidence that the adaptive filter-FLC integration with optimal coefficients minimizes torque and flux ripples with reduction of total harmonic distortion generated in the three-phase currents.