1,720,963 research outputs found
Peak-shaving in district heating systems through optimal management of the thermal request of buildings
Get PDFThis paper aims at analyzing the opportunities for peak load shaving in district heating systems using a physical simulation tool. Using the proposed approach it is possible to examine the effects on the total load that can be obtained by adopting management strategies such as variation in the thermal request profile of the buildings or installation of local storage systems. The model is applied to the optimization of start-up time of the heating system in the buildings located in a selected distribution network. Proper constraints are introduced in order to avoid significant effects on the indoor temperatures of the buildings, so that acceptable comfort standard can be guaranteed. The primary energy consumption at the thermal plants is considered as the objective function to be minimized. An application to a portion of the Turin district heating network, which is the largest network in Italy, is presented. Results show that even in the case only small changes are applied, reductions in annual primary energy consumption up to 0.4% can be obtained without any additional investment cost. This opens the door larger positive impact through implementation of more complex operating strategy
Differential conductance of an electrolytic cell in the presence of deposition of a coating material on the electrode
No full textThe influence of the deposition of a coating material on the electrode surface in an electrochemical cell on the current-voltage characteristics is investigated. The surface covering of particles is evaluated from the surface current density of the ions. The current-voltage characteristics for the cases when the surface deposition increases or reduces the surface resistance of the electrode are derived. The differential conductance, defined as the derivative of the current with respect to the applied voltage, is evaluated. The cases of small and large overpotential are considered. An extension of the model to a real situation in which the external potential applied to the cell is a step of a given amplitude is also considered
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The United Kingdom electricity market mechanism: A tool for a battery energy storage system optimal dispatching
No full textIn this paper, the role of a Battery Energy Storage System (BESS) in the United Kingdom (UK) electricity market is investigated. Such device is selected since research works related to the topic demonstrate that BESSs help facing challenges caused by renewable energy sources increasing penetration in the power systems’ field. Indeed, in the next future, BESSs will assume a relevant role thanks to their fast response time. In the present paper, an optimization model is implemented to encode the UK market rules and output the optimal set of offers on day-ahead and intraday markets, dynamic frequency response services and imbalance settlement. The market rules are formalised in a mathematical model considering market temporal sequencing and BESS technical limitations. The tool also models the state of energy management, necessary since BESSs are energy limited assets. Objective function and constraints are linearized to define a Mixed Integer Linear Programming problem to reduce the computational burden and to integrate the model in the Energy Management System previously developed at University of Genoa. Specific tests are performed including and excluding ancillary services to evaluate the related advantages. The obtained outcomes reveal that ancillary services are the most convenient options within all the implemented scenarios
An Energy Management System to Optimize the Participation in the Day Ahead and Ancillary Service Markets
No full textThis paper presents the evolution of an Energy Management System developed by University of Genoa aimed at minimizing the operation costs of plants and Microgrids (MGs). In the updated version, the Ancillary Service Market (ASM) and Day Ahead Market (DAM) mechanisms are modelled to include the possibility of trading in these markets. Since the Transmission System Operator (TSO) rejection or acceptance in the ASM cannot be forecasted, a statistical approach is proposed. Specifically, the optimization process is divided in two steps: initially the optimal dispatching program is computed, identifying DAM offers and ASM bid and offers that can be proposed. Then, a Monte Carlo method is implemented: by receiving a user defined acceptance rate, the TSO decisions are simulated by extracting sets of awarded proposals from a Probability Density Function (PDF). For each extraction, the second step of the optimization re-dispatches the units based on the bidding program. A PDF of the revenues/costs is the final outcome. Thereafter, the statistical moments of the resulting PDF can be analysed to estimate the profitability of the participation to the markets. A test performed on a real plant over one year demonstrates that longtime horizons may be simulated within reasonable computational time allowing to maintain a high level of details to model devices and markets
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
