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Publications

2018

Planning woody biomass supply in hot systems under variable chips energy content

Authors
Marques, A; Rasinmaki, J; Soares, R; Amorim, P;

Publication
BIOMASS & BIOENERGY

Abstract
The growing economic importance of the biomass-for-bioenergy in Europe motivates research on biomass supply chain design and planning. The temporally and geographically fragmented availability of woody biomass makes it particularly relevant to find cost-effective solutions for biomass production, storage and transportation up to the consumption facility. This paper addresses tactical decisions related with optimal allocation of wood chips from forest residues at forest sites to terminals and power plants. The emphasis is on a "hot-system" with synchronized chipping and chips transportation at the roadside. Thus, decisions related with the assignment of chippers to forest sites are also considered. We extend existing studies by considering the impact of the wood chips energy content variation in the logistics planning. This is a key issue in biomass-for-bioenergy supply chains. The higher the moisture content of wood chips, the lower its net caloric value and therefore, a larger amount of chips is needed to meet the contracted demand. We propose a Mixed Integer Programming (MIP) model to solve this problem to optimality. Results of applying the model in a biomass supply chain case in Finland are presented. Results suggest that a 20% improvement in the supplier profit can be obtained with the proposed approach when compared with a baseline situation that relies on empirical estimates for a fixed and known moisture content in the end of an obliged storage age.

2018

Disposable electrochemical detection of breast cancer tumour marker CA 15-3 using poly(Toluidine Blue) as imprinted polymer receptor

Authors
Ribeiro, JA; Pereira, CM; Silva, AF; Sales, MGF;

Publication
BIOSENSORS & BIOELECTRONICS

Abstract
In this work, electrically-conducting poly(Toludine Blue) was employed for the first time as synthetic receptor film, prepared by Molecular Imprinting strategies and using electrochemical methods, for the specific screening of breast cancer biomarker Carbohydrate Antigen 15.3 (CA 15-3). The protein imprinted poly(Toluidine Blue) film was grown in a pre-formed Toluidine Blue (TB) tailed SAM at the AuSPE surface, which greatly enhanced the stability against degradation of the Molecular Imprinted Polymer (MIP) film at the electrode surface. The MIP receptor film recognition ability towards the protein was investigated by fitting data to Freundlich isotherm. The binding affinity (K-p) obtained for the MIP system was significantly higher (similar to 12-fold) to that obtained for the NIP system, demonstrating the success of the approach in creating imprinted materials that specifically respond to CA 15-3 protein. The incubation of the MIP modified electrode with increasing concentration of protein (from 0.10 U mL(-1) to 1000 U mL(-1)) resulted in a decrease of the ferro/ferricyanide redox current. The device displayed linear response from 0.10 U mL(-1) to 100 U mL(-1) and LODs below 0.10 U mL(-1) were obtained from calibration curves built in neutral buffer and diluted artificial serum, using DPV technique, enabling the detection of the protein biomarker at clinically relevant levels. The developed MIP biosensor was applied to the determination of CA 15-3 in spiked serum samples with satisfactory results. The developed device provides a new strategy for sensitive, rapid, simple and cost-effective screening of CA 15-3 biomarker. Importantly, the overall approach seems suitable for point-of-care (PoC) use in clinical context.

2018

Economic and environmental benefits of using textile waste for the production of thermal energy

Authors
Nunes, LJR; Godina, R; Matias, JCO; Cataldo, JPS;

Publication
JOURNAL OF CLEANER PRODUCTION

Abstract
There is a growing demand for alternative forms of energy that could firstly replace fossil fuels, with the environmental advantages resulting therefrom, but that could be as well economically more beneficial by allowing companies to obtain competitive advantages from the aforementioned alternative forms of energy. In this sense, the use of waste to produce thermal energy is presented as an alternative worthy of study. In this paper, an analysis is made of the use of waste from the textile industry, more precisely cotton waste, which is used as a renewable resource for the production of thermal energy. After the characterization of the waste, the energetic potential is determined comparatively to other fuels such as woodchips and wood pellets. A comparative economic assessment with other fuels is carried out. The obtained results show that the cotton briquettes have a heating value of 16.80 MJ/kg and a cost of 0.006 (sic)/kWh when used as fuel. This predicts an annual reduction in fuel cost of 80, 75 and 70% when compared with fuel-oil, wood pellets and wood chips, respectively. Thus, the use of cotton waste could be a viable alternative, economically and environmentally, to produce thermal energy.

2018

Novel Control Strategy for Modular Multilevel Converters Based on Differential Flatness Theory

Authors
Mehrasa, M; Pouresmaeil, E; Taheri, S; Vechiu, I; Catalao, JPS;

Publication
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS

Abstract
This paper aims to present a novel control strategy for modular multilevel converters (MMC) based on differential flatness theory, in which instantaneous active and reactive power values are considered as the flat outputs. To this purpose, a mathematical model of the MMC taking into account dynamics of the ac-side current and the dc-side voltage of the converter is derived in a d-q reference frame. Using this model, the flat outputs-based dynamic model of MMC is obtained to reach the initial value of the proposed controller inputs. In order to mitigate the negative effects of the input disturbance, model errors, and system uncertainties on the operating performance of the MMC, the integral-proportional terms of the flat output errors are added to the initial inputs. This can be achieved through defining a control Lyapunov function which can ensure the stability of the MMC under various operating points. Moreover, the small-signal linearization method is applied to the proposed flat output-based model to separately evaluate the variation effects of controller inputs on flat outputs. The proficiency of the proposed method is researched via MATLAB simulation. Simulation results highlight the capability of the proposed controller in both steady-state and transient conditions in maintaining MMC currents and voltages, through managing active and reactive power.

2018

Open Source Web Platform for the Analysis of Academic Spin-offs

Authors
Almeida, F; Cunha, E;

Publication
Journal of Information Systems Engineering and Business Intelligence

Abstract
Universities have assumed an increasingly important role in transferring technology to society with a strong economic impact. The companies originated from the academic environment, called academic spin-offs, have fostered the appearance of new projects based on emerging technologies and knowledge, created by young students and researchers who seek to launch their own business and generate new jobs in society. However, the number of existing studies on academic spin-offs is limited and restricted to the specific national realities, and the results of these studies are typically incorporated only in scientific manuscripts. In this sense, this study proposes a web platform that allows the analysis of academic spin-offs according to multiple dimensions, such as firm, institutions, individual, localization, science parks, financial data and corporate actions. The application is built exclusively in open source technologies and allows data to be explored in real-time and interactively. The results obtained allow us to evaluate the behavior of the application regarding fundamental elements in the success of the adoption of a Web application, such as usability, security, interoperability and portability.

2018

Online Job Search: Study of Users' Search Behavior using Search Engine Query Logs

Authors
Mansouri, B; Zahedi, MS; Campos, R; Farhoodi, M;

Publication
ACM/SIGIR PROCEEDINGS 2018

Abstract
Over the last few years, an increasing number of user's and enterprises on the internet has generated a global marketplace for both employers and job seekers. Despite the fact that online job search is now more preferable than traditional methods - leading to better matches between the job seekers and the employer's intents - there is still little insight into how online job searches are different from general web searches. In this paper, we explore the different characteristics of online job search and their differences with general searches, by leveraging search engine query logs. Our experimental results show that job searches have specific attributes which can be used by search engines to increase the quality of the search results.

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