The rapid rise in inequality is often seen to go in-hand with resource overuse. Examples include water extraction in Pakistan, land degradation in Bangladesh, forest harvesting in Sub-Saharan Africa ...and industrial fishing in Lake Victoria. While access to ecosystem services provided by common pool resources mitigates poverty, exclusive access to technology by wealthy individuals may fuel excessive resource extraction and deplete the resource, thus widening the wealth gap. We use a stylised social-ecological model, to illustrate how a positive feedback between wealth and technology may fuel local inequality. The resulting rise in local inequality can lead to resource degradation and critical transitions such as ecological resource collapse and unexpected increase in poverty. Further, we find that societies may evolve towards a stable state of few wealthy and many poor individuals, where the distribution of wealth depends on how access to technology is distributed. Overall, our results illustrate how access to technology may be a mechanism that fuels resource degradation and consequently pushes most vulnerable members of society into a poverty trap.
•A positive wealth-technology feedback may fuel inequality in a growing society.•Heterogeneous access to technology can potentially accelerate rise in inequality.•Left unabated, rising inequality can trigger resource collapse and poverty.•Equity and access to resources are key for ecological resilience and poverty reduction.
The traditional morpheme order studies in second language acquisition have tried to demonstrate the existence of a fixed order of acquisition of English morphemes, regardless of the second language ...learner's background. Such orders have been taken as evidence of the preprogrammed nature of language acquisition. This article argues for a process‐based, dynamic explanation of development, in which each developmental step is based on the dynamic interaction of all processes involved. Due to the complexity of these interactions, the developmental process cannot be predetermined and fixed. Although stages of development like the acquisition order of morphemes are commonly observed as a grand sweep effect at the group level, these stages may be meaningless at the level of the individual language learner. This paradox shows we can only make the observations that our method allows us. If we are interested in grand sweep effects that may be generalizable to large populations of learners, we will have to carry out group studies with representative samples that can be analyzed using Gaussian statistics based on the normal distribution. But if we are interested in how an individual learner progresses over time as a result of changing variables in a changing context, we will have to conduct longitudinal studies and use nonlinear methods of analysis.
People walking side by side spontaneously synchronize their steps on some occasions but not on others, which poses a challenge to theories of perception-action based on interactive dynamic systems. ...How can action be spontaneously entrained by some sources of perceptual information while others are selectively ignored? The predictive processing framework suggests that saliency factors such as stimulus predictability, consistent deviation, and interactivity of the stimulus control the coupling between the motor system and perceptual information. To test this, we compared entrainment of gait cadence by two interactive auditory stimuli and two noninteractive but predictable, faster than preferred stimuli that were isochronous or statistically matched to gait. One interactive stimulus had properties that are optimal for mutual entrainment as per a mathematical model of interactive periodic processes, the Kuramoto system. In particular, the stimulus was faster than the participant but also adapted its rate to a limited degree as function of phase mismatch with the participant's steps. The second interactive stimulus fully mirrored the gait cycle hence it did not induce mutual synchronization. Furthermore, healthy participants were compared to ones with impaired gait due to Parkinson's disease, a model disorder that makes movement more dependent on external cueing. The mutually interactive condition produced the strongest entrainment, in patients and healthy participants, without differences between groups. The stimulus adapted to each participant's gait while maintaining a consistent lead in phase. Auditory-motor coupling may be enhanced by stimuli that are not only predictable but also interactive in that they align to self-generated movements.
In this paper, the indirect adaptive control of a special class of hybrid systems is proposed. The proposed control scheme is based on g-normal fuzzy relational hybrid models (g-Normal FRHMs) in ...which the model of both plant and controller are proposed to be modeled by FRHM structure. There is an assumption on control action to be of continuous-valued type. In order to design a control scheme for both regulation and reference tracking, an additional simplifying assumption is considered. Indeed, when the tuning mechanism is extracted, it is assumed that the defuzzifier of the controller’s model and the fuzzifier of the plant’s model are approximately inverse of each other and can be simplified. The proposed control approach is then applied to a DC-DC buck converter as our case study. The simulation results show that the proposed adaptive control based on g-Normal FRHM can regulate and also track the reference input in the presence of both load and supply voltage disturbance.
Although great progress has been made in the last 40 years, efficient operation of water reservoir systems still remains a very active research area. The combination of multiple water uses, ...non-linearities in the model and in the objectives, strong uncertainties in inputs and high dimensional state make the problem challenging and intriguing. The purpose of this paper is to review, in a strict Control Theory perspective, recent and significant advances in designing management policies for water reservoir networks, under economic, social and environmental constraints. A general and thorough problem formulation is provided, along with a description of traditional solution techniques, their limitations and possible alternative approaches.
•In this study we model a complex fluid dynamics behaviour using the low-ordered simplified nonlinear discrete model.•The current complex phenomena of the coupling iteration between fluid and solid ...mechanics has the high-order-terms or huge calculations, for example CFD.•We examine changes the theoretical model and different equation from the discrete mechanics with bifurcation based on chaos theory and post-buckling theory.•We obtain approximate results from both experimental data and present method in global view.•We forecast this complex phenomena using global bifurcation diagram based on non-equilibrium discrete mechanics by this present model.
The dynamic bifurcation analysis of the nonlinear oscillation of a simple fluidelastic structure is presented. This structure is a cantilever beam in a flow, and it behaves as a nonlinear system without potential energy. The structure demonstrates complex flutter behaviour that varies with the controlled flow velocity. We observe the flutter behaviour in a flow experiment, and the motion is characterised with this present model based on chaos theory of discrete dynamics. We can readily find the solution of the simple system, with which it is possible to create a map of the complex flutter behaviour.
AbstractIntroduction: Due to rapid expansion of population, there is an increase in the number of water users. As a result, optimal water allocation has become a pivotal issue. System dynamics is a ...suit methodology for simulating and representing of water availability in complex condition and impacts of water resources usage over time. In this study, a dynamic water allocation model within Vensim GUI was developed for the agricultural and environmental water resources of Khamiriza catchment.Methods: The model consists of two separate sections; the first part is a water balance module which is designed to provide surface water and groundwater simulations; the other part is a water allocation sub-model. After the development of the model, the water balance simulation optimized by optimizing the surface water and groundwater against observed data.Findings: The water use policy includes the conjunctive use of groundwater and surface water to meet drinking, industrial, agricultural, and environmental demands. The results suggest that under current situation the quantity of available surface and groundwater could be insufficient to meet the demands of different sectors within the basin. Therefore, a scenario containing improved irrigation efficiency and 30% of the land in fallow may lead to the allocation vulnerability.Conclusion:The results of this application indicate that system dynamics can be considered as an innovative tool in the planning and allocating water resources. Moreover, conjunctive use of groundwater and surface water resources may lead to a better water allocation policy.
This study examined how a group of Chinese EFL learners’ task motivation progressed during a particular group communicative task in a natural classroom context, and what variables were perceived to ...have affected the students’ ongoing motivational dynamics during the task. A mixed-methods approach was adopted to gather a broad range of data, including the participants’ ratings of their moment-by-moment task motivation intensity, their corresponding written explanations for the ratings, and focus group interviews. An intact class of 39 s-year college students participated in the study. The results revealed not only fluctuations in motivation on a minute-by-minute basis during task performance, but also variations in motivational change patterns across learners, suggesting that task motivation is dynamic even in the very short term. Attributions of such fluctuations, as perceived by the participants, included a multitude of immediate situational factors associated with behavioral, cognitive, motivational, linguistic, and contextual influences. In particular, the act of actively presenting views enhanced their motivation to the greatest degree, while a shortage of conceptual preparation (i.e. having no ideas to share) inhibited it to the largest extent. Pedagogical implications are provided based on these findings.
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