472 research outputs found
Market Coupling as the Universal Algorithm to Assess Zonal Divisions
Adopting a zonal structure of electricity market requires specification of
zones' borders. In this paper we use social welfare as the measure to assess
quality of various zonal divisions. The social welfare is calculated by Market
Coupling algorithm. The analyzed divisions are found by the usage of extended
Locational Marginal Prices (LMP) methodology presented in paper [1], which
takes into account variable weather conditions. The offered method of
assessment of a proposed division of market into zones is however not limited
to LMP approach but can evaluate the social welfare of divisions obtained by
any methodology.Comment: 5 page
The Scheme of a Novel Methodology for Zonal Division Based on Power Transfer Distribution Factors
One of the methodologies that carry out the division of the electrical grid
into zones is based on the aggregation of nodes characterized by similar Power
Transfer Distribution Factors (PTDFs). Here, we point out that satisfactory
clustering algorithm should take into account two aspects. First, nodes of
similar impact on cross-border lines should be grouped together. Second,
cross-border power flows should be relatively insensitive to differences
between real and assumed Generation Shift Key matrices. We introduce a
theoretical basis of a novel clustering algorithm (BubbleClust) that fulfills
these requirements and we perform a case study to illustrate social welfare
consequences of the division.Comment: 7 page
Study of natural ventilation design by integrating the multi-zone model with CFD simulation
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2005.Includes bibliographical references (p. 150-154).Natural ventilation is widely applied in sustainable building design because of its energy saving, indoor air qualify and indoor thermal environment improvement. It is important for architects and engineers to accurately predict the performance of natural ventilation, especially in the building design stage. Unfortunately, there is not any good public tool available to predict the natural ventilation design. The integration of the multi-zone model and the computational fluid dynamics (CFD) simulation provides a way to assess the performance of natural ventilation in whole buildings, as well as the detailed thermal environmental information in some particular space. This work has coupled the multi-zone airflow model with the thermal model. A new program, called MultiVent, has been developed with a web-server that can provide online calculation for the public. The MultiVent program can simultaneously simulate the indoor air temperature and airflow rate with known indoor heat sources for buoyancy dominated, buoyancy-wind combined and wind dominated cases. To properly apply the MultiVent program to the natural ventilation design, two configurations in naturally ventilated buildings should be carefully studied: the atrium and large openings between the zones. A criterion has been set up for dividing the large opening and the connected atrium space into at least two sub-openings and sub-zones. The results of the MultiVent calculation can provide boundary conditions to the CFD simulation for some particular zone. In order to correctly simulate the particular space with CFD, the location and conditions at the integrating surface (boundary surface) have been studied. This work suggested that the simulation zone should include part of the connected atrium space when(cont.) the occupied room is simulated with CFD. There are two options to integrate the MultiVent and CFD simulation through different boundary conditions: velocity (mass) integration and pressure integration. The case studies of this work showed that both of them can generate good CFD simulation results.by Gang Tan.Ph.D
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Phase change thermal energy storage for the thermal control of large thermally lightweight indoor spaces
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Energy storage using Phase Change Materials (PCMs) offers the advantage of higher heat capacity at specific temperature ranges, compared to single phase storage. Incorporating PCMs in lightweight buildings can therefore improve the thermal mass, and reduce indoor temperature fluctuations and energy demand. Large atrium buildings, such as Airport terminal spaces, are typically thermally lightweight structures, with large open indoor spaces, large glazed envelopes, high ceilings and non-uniform internal heat gains. The Heating, Ventilation and Air-Conditioning (HVAC) systems constitute a major portion of the overall energy demand of such buildings. This study presented a case study of the energy saving potential of three different PCM systems (PCM floor tiles, PCM glazed envelope and a retrofitted PCM-HX system) in an airport terminal space. A quasi-dynamic coupled TRNSYS®-FLUENT® simulation approach was used to evaluate the energy performance of each PCM system in the space. FLUENT® simulated the indoor air-flow and PCM, whilst TRNSYS® simulated the HVAC system. Two novel PCM models were developed in FLUENT® as part of this study. The first model improved the phase change conduction model by accounting for hysteresis and non-linear enthalpy-temperature relationships, and was developed using data from Differential Scanning Calorimetry tests. This model was validated with data obtained in a custom-built test cell with different ambient and internal conditions. The second model analysed the impact of radiation on the phase change behaviour. It was developed using data from spectrophotometry tests, and was validated with data from a custom-built PCM-glazed unit. These developed phase change models were found to improve the prediction errors with respect to conventional models, and together with the enthalpy-porosity model, they were used to simulate the performance of the PCM systems in the airport terminal for different operating conditions. This study generally portrayed the benefits and flexibility of using the coupled simulation approach in evaluating the building performance with PCMs, and showed that employing PCMs in large, open and thermally lightweight spaces can be beneficial, depending on the configuration and mode of operation of the PCM system. The simulation results showed that the relative energy performance of the PCM systems relies mainly on the type and control of the system, the night recharge strategy, the latent heat capacity of the system, and the internal heat gain schedules. Semi-active systems provide more control flexibility and better energy performance than passive systems, and for the case of the airport terminal, the annual energy demands can be reduced when night ventilation of the PCM systems is not employed. The semi-active PCM-HX-8mm configuration without night ventilation, produced the highest annual energy and CO2 emissions savings of 38% and 23%, respectively, relative to a displacement conditioning (DC) system without PCM systems.UK Engineering and Physical Sciences Research Counci
Corporate Social Responsibility and Firm Performances: bridging innovation and financial outcomes to stakeholder theory
This thesis aims to investigate if and how the attention towards stakeholder
groups affects ability and strategy of firms and corporates on innovation and
performances.
The framework of the Stakeholder Theory is assumed as reference for the
origin and concept of Corporate Social Responsibility. On this basis, specific
attention is dedicated to empirical studies on a database created by the research
group at the University of Genoa in cooperation with the Italian Ministry of
Economic Development. The data of the firms are analysed by means of
clustering techniques and bivariate probit model
Results offer implications from both theoretical and practical points of views.
In particular, the links between practices in Corporate Social Responsibility and
corporate innovation are empirically confirmed and economically addressed, also
putting into evidence how commitment in Corporate Social Responsibility
initiatives increase the probability to innovate in product and in process. The
results outlined in the thesis show that a holistic approach towards Corporate
Social Responsibility is the key factor in order to the achieve effective
performance of innovation and to foster product and process innovations. Firms
are expected to implement Corporate Social Responsibility practices in all
Corporate Social Responsibility areas, without neglecting any stakeholder and, in
the ideal situation, the innovation outcomes and the firm performances results
closely linked to the ability of firms to anticipate and meet the stakeholder needs.
Finally, beside the insights to corporate strategies, the thesis offers a
methodology to support banks in the calculation of default probability of firms by
exploiting the positive inter-linkage between Corporate Social Responsibility and
finance and risk. Based on Basel Standards and including fields monitored
through Corporate Social Responsibility indicators, the proposed approach allows
understanding of corporates\u2019 capabilities to create value and demonstrate low risk
of claims, fines and default
Analysis of Land Use Change: Theoretical and Modeling Approaches
This Web Book provides information on basic concepts and trends in land use change, and then reviews the state of the art in land use theory and empirical modeling. It concludes by summarizing the main issues pertaining to theories and models of land use change, discusses selected issues in of a more general concern in the context of the analysis of land use change and outlines future research directions.https://researchrepository.wvu.edu/rri-web-book/1000/thumbnail.jp
Satellite Communications
This study is motivated by the need to give the reader a broad view of the developments, key concepts, and technologies related to information society evolution, with a focus on the wireless communications and geoinformation technologies and their role in the environment. Giving perspective, it aims at assisting people active in the industry, the public sector, and Earth science fields as well, by providing a base for their continued work and thinking
Climate Change and Environmental Sustainability-Volume 4
Anthropogenic activities are significant drivers of climate change and environmental degradation. Such activities are particularly influential in the context of the land system that is an important medium connecting earth surface, atmospheric dynamics, ecological systems, and human activities. Assessment of land use land cover changes and associated environmental, economic, and social consequences is essential to provide references for enhancing climate resilience and improving environmental sustainability. On the one hand, this book touches on various environmental topics, including soil erosion, crop yield, bioclimatic variation, carbon emission, natural vegetation dynamics, ecosystem and biodiversity degradation, and habitat quality caused by both climate change and earth surface modifications. On the other hand, it explores a series of socioeconomic facts, such as education equity, population migration, economic growth, sustainable development, and urban structure transformation, along with urbanization. The results of this book are of significance in terms of revealing the impact of land use land cover changes and generating policy recommendations for land management. More broadly, this book is important for understanding the interrelationships among life on land, good health and wellbeing, quality education, climate actions, economic growth, sustainable cities and communities, and responsible consumption and production according to the United Nations Sustainable Development Goals. We expect the book to benefit decision makers, practitioners, and researchers in different fields, such as climate governance, crop science and agricultural engineering, forest ecosystem, land management, urban planning and design, urban governance, and institutional operation.Prof. Bao-Jie He acknowledges the Project NO. 2021CDJQY-004 supported by the Fundamental Research Funds for the Central Universities and the Project NO. 2022ZA01 supported by the State Key Laboratory of Subtropical Building Science, South China University of Technology, China. We appreciate the assistance of Mr. Lifeng Xiong, Mr. Wei Wang, Ms. Xueke Chen, and Ms. Anxian Chen at School of Architecture and Urban Planning, Chongqing University, China
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