Search results for "system dynamics."

Modeling and design of Net ZEBs as integrated energy systems

2015

Net-zero energy buildings (Net ZEBs) are emerging as a quantifiable design concept and a promising solution to minimizing the environmental impact of buildings. This is the main concept that is focused on this chapter with emphasis on dynamic modeling and examples of technological approaches to achieve net-zero energy. Appropriate modeling of building-integrated solar energy systems is essential for the design of Net ZEBs and the study of optimal control strategies. The net-zero energy balance may be achieved through a combination of passive and active solar technologies, heat pumps, combined heat and power, and energy efficiency measures to reduce energy consumption for lighting and applia…

Individualizing deep dynamic models for psychological resilience data

2020

ABSTRACTDeep learning approaches can uncover complex patterns in data. In particular, variational autoencoders (VAEs) achieve this by a non-linear mapping of data into a low-dimensional latent space. Motivated by an application to psychological resilience in the Mainz Resilience Project (MARP), which features intermittent longitudinal measurements of stressors and mental health, we propose an approach for individualized, dynamic modeling in this latent space. Specifically, we utilize ordinary differential equations (ODEs) and develop a novel technique for obtaining person-specific ODE parameters even in settings with a rather small number of individuals and observations, incomplete data, an…

The superior effect of nature based solutions in land management for enhancing ecosystem services

2017

The rehabilitation and restoration of land is a key strategy to recover services -goods and resources- ecosystems offer to the humankind. This paper reviews key examples to understand the superior effect of nature based solutions to enhance the sustainabilit y of catchment systems by promoting desirable soil and landscape functions. The use of concepts such as connectivity and the theory of system thinking framework allowed to review coastal and river management as a guide to evaluate other strategies to achieve sustainability. In land management NBSs are not mainstream management. Through a set of case studies: organic farming in Spain; rewilding in Slovenia; land restoration in Iceland, s…

Demand and Supply Model for the Natural Gas Supply Chain in Colombia

2018

Natural gas is considered the transitional fuel for excellence between fossil and renewable sources, considering its low cost, greater efficiency and lesser effects on the environment. This has led to increased demand levels worldwide, requiring the intervention of public and private actors to meet such demand. In this research, we study the natural gas supply chain in Colombia using system dynamics modelling. The results allow to contrast both the behaviour of the production and transport levels and the behaviour of the demand from the consumption sectors, allowing to identify capacity levels to be developed considering implementation times and percentages of coverage in the supply.

Introducing in a Non-Profit Organisation a CSR Strategy through a Learning Oriented Perspective: the Emssanar case-study

2008

A synthesis of feasible control methods for floating offshore wind turbine system dynamics

2021

Abstract During the past decade, the development of offshore wind energy has transitioned from near shore with shallow water to offshore middle-depth water regions. Consequently, the energy conversion technology has shifted from bottom-fixed wind turbines to floating offshore wind turbines. Floating offshore wind turbines are considered more suitable, but their cost is still very high. One of the main reasons for this is that the system dynamics control method is not well-adapted, thereby affecting the performance and reliability of the wind turbine system. The additional motion of the platform tends to compromise the system’s performance in terms of power maximization, power regulation, an…

Supply chain modelling and analysis: an application of Latin square to a repeated coupling of non-linear differential equations

2011

In the last 50 years, Forrester’s system dynamics techniques have been adopted to analyse problems and find solutions for global supply chains. An important topic in production-inventory system modelling is the design of experiment. The aim of this paper is to present an application of a statistical technique of design of experiment, the Latin Square Design, to set a combination of input values for the initial-value problem of non-linear repeated coupling of first-order differential equations modelling a production-inventory system. This design permits to reduce the number of experiments while allowing statistical analysis for testing the significance of the studied parameters.

Simulations of networked critical infrastructures

2018

Master's thesis Information- and communication technology IKT590 - University of Agder 2018 Critical infrastructure (CI) refers to assets that are essential for the functioning of a society and economy, such as telecommunication/ICT; energy generation, transmission and distribution; financial sector; etc. CIs are tightly coupled, creating a complex system where failures propagate from a disrupted CI to other CIs, aggravating and prolonging the societal impact through cascading effects. This thesis extends a system dynamic model by Eliza Canzani describing how a failed critical infrastructure that cannot deliver products and services impacts other critical infrastructures, and how a critical…

Evolution of a Non-Hermitian Quantum Single-Molecule Junction at Constant Temperature

2021

This work concerns the theoretical description of the quantum dynamics of molecular junctions with thermal fluctuations and probability losses. To this end, we propose a theory for describing non-Hermitian quantum systems embedded in constant-temperature environments. Along the lines discussed in [A. Sergi et al., Symmetry 10 518 (2018)], we adopt the operator-valued Wigner formulation of quantum mechanics (wherein the density matrix depends on the points of the Wigner phase space associated to the system) and derive a non-linear equation of motion. Moreover, we introduce a model for a non-Hermitian quantum single-molecule junction (nHQSMJ). In this model the leads are mapped to a tunneling…

POLICY INNOVATION AND IMPLEMENTATION IN PUBLIC SECTOR: COMPLEXITIES, DYNAMICS AND UNCERTAINTIES

This research is expected to contribute to the knowledge base on how an effective impact assessment and adoption of innovations in the public sector could be facilitated. The need for trans-disciplinary assessment of the long-term potential impacts of innovation-driven policies may well be met with system dynamics as part of the dynamic performance management approach by way of modelling based simulation and analysis. Moreover, such analysis may contribute to learning and the accumulation of a knowledge repository that enables strategy developers, policy designers and decision makers to arrive at unexpected (often called counterintuitive) conclusions prior to policy implementation. Such ins…