5,655 research outputs found
Dynamic Scaling of Non-Euclidean Interfaces
The dynamic scaling of curved interfaces presents features that are
strikingly different from those of the planar ones. Spherical surfaces above
one dimension are flat because the noise is irrelevant in such cases. Kinetic
roughening is thus a one-dimensional phenomenon characterized by a marginal
logarithmic amplitude of the fluctuations. Models characterized by a planar
dynamical exponent , which include the most common stochastic growth
equations, suffer a loss of correlation along the interface, and their dynamics
reduce to that of the radial random deposition model in the long time limit.
The consequences in several applications are discussed, and we conclude that it
is necessary to reexamine some experimental results in which standard scaling
analysis was applied
Marine-friendly antifouling coating based on the use of a fatty acid derivative as a pigment
This study was devoted to examining the application of copper dodecanoate as a non-contaminant antifouling pigment due to its low copper content and fatty acid nature. For this purpose, antifouling paints with mono-component epoxy resin and rosin matrixes were formulated, and their antifouling efficiency was evaluated. Before its incorporation into the different formulations, the synthesized pigment was characterized. Immersion tests in a marine environment were carried out for 12 months to evaluate the antifouling efficiency of the developed paints; the results were compared with those from a commercial paint. The antifouling efficiency of the new epoxy formulation was found to be considerably higher than that of the rosin formulation and very similar to that of the commercial paint. Most importantly, the release of copper from the epoxy paint formulated with copper dodecanoate was 73.5% lower than that of the commercial paint, suggesting prolonged activity of the developed paint.Peer ReviewedPostprint (published version
Assessing the quality of the relation between scalarizing function parameters and solutions in multiobjective optimization
Different Multi-Objective Optimization Methods
(MOOM) for solving Multi-Objective Optimization Problems
(MOOP) have been suggested in the literature. These methods
often comprise two stages (not necessarily sequential): i) the
search for the Pareto-optimal set and ii) the selection of a single
solution from this non-dominated set. Various studies
comparing performance of particular aspects of these methods
have been carried out. However, a theoretical support that
changes on the preferences of a Decision Maker (DM) will be
reflected in the same way on the solution of the MOOP given by
the MOOM has not been presented. In this work a consistency
measure to assess MOOM is proposed. It will used to compare
the performance of different methods available in the
literature. This study was performed using some benchmark
test problems, with two criteria.This work was supported in part by the Portuguese Fundacao para a Ciencia e Tecnologia under grants: PTDC/GES/70168/2006 and SFRH/BD/22808/2005
A FLAMINGOS Deep Near Infrared Imaging Survey of the Rosette Complex I: Identification and Distribution of the Embedded Population
We present the results of a deep near-infrared imaging survey of the Rosette
Complex. We studied the distribution of young embedded sources using a
variation of the Nearest Neighbor Method applied to a carefully selected sample
of near-infrared excess (NIRX) stars which trace the latest episode of star
formation in the complex. Our analysis confirmed the existence of seven
clusters previously detected in the molecular cloud, and identified four more
clusters across the complex. We determined that 60% of the young stars in the
complex and 86% of the stars within the molecular cloud are contained in
clusters, implying that the majority of stars in the Rosette formed in embedded
clusters. We compare the sizes, infrared excess fractions and average
extinction towards individual clusters to investigate their early evolution and
expansion. We found that the average infrared excess fraction of clusters
increases as a function of distance from NGC 2244, implying a temporal sequence
of star formation across the complex. This sequence appears to be primordial,
possibly resulting from the formation and evolution of the molecular cloud and
not from the interaction with the HII region.Comment: Accepted by Astrophysical Journa
A control strategy for a three-phase four-wire shunt active filter
This paper presents a control strategy for a three-
phase four-wire shunt active filter. The shunt active filter is a custom-power device capable to compensate, in real time, harmonics, unbalances and power factor in an electrical
installation. In this work the power circuit is based on a three-leg
IGBT inverter, with the dc-link composed by two capacitors
connected in split. Thus the neutral point is connected directly to
the midpoint of the dc-link capacitors. Its control system is
composed by an algorithm based on the active and non-active
currents together with a synchronizing circuit, and a novel
algorithm to keep the voltages of the dc-link capacitors balanced
and regulated. Due to the applied power-inverter topology, it is
imperative to keep these voltages of the dc-link capacitors balanced in order to avoid malfunctioning of the active filter. To validate the proposed control strategy, simulation and experimental results are presented
iLeanDMAIC – A methodology for implementing the lean tools
Organizations focus must reside in their constant desire for improvement in order to satisfy their clients as a result of high-quality products, thus maximizing their profits through a waste reduction in the flow production. Lean thinking allows organizations to identify and eliminate wastes within the organization. The use of lean tools is considered a simple, efficient and cost-effective solution to achieve productivity and profit. DMAIC (Define, Measure, Analyze, Improve, Control) is a problem-solving methodology that improves processes, allows defect reduction and reduction of process variability, allowing companies to continuously improve their efficiency and performance. In this work, a combined methodology iLeanDMAIC based on Lean Tools and DMAIC was developed, aiming to help organizations to easily and accurately solve their problems. It includes a case-study implementation on an organization of the sector of wood products. We were able to successfully validate this methodology and to show its efficacy in enhancing production. Results using iLeanDMAIC allowed a reduction time in changeover in the assembly machine (from 39 min to 17 min), presenting this a 44% gain on manufacture. iLeanDMAIC can help organizations thrive against their competitors, make their business more cost-effective and efficient.info:eu-repo/semantics/publishedVersio
Neobični valovi u akvatoriju Campos (Brazil)
Freak waves occur abundantly in Campos Basin, located on the northeast coast of Rio de Janeiro, Brazil in the South Atlantic Ocean. This surprising and unexpected discovery was made from a search of the time-series data of wave measurements recorded in the Campos Basin from 1991 to 1995. In a study on the occurrence of freak waves and their relevant properties, we have also found that freak waves are not of rare occurrence as conventionally presumed, and they occur not only during storm conditions but also during fair weather states as well. While the conventional approach of spectrum analysis provides some weak inference of freak wave effects, the basically stationary random process approach is clearly incapable of contending with the localized non-stationary process of freak wave occurrences.Neobični se valovi često pojavljuju u akvatoriju Campos, sjeveroistočno od Rio de Janeira (Brazil) u južnom Atlantiku. To iznenađujuće i neočekivano otkriće načinjeno je na osnovi vremenskih nizova prikupljenih valomjerima u akvatoriju Campos u
razdoblju od 1991. do 1995. godine. Istražujući pojavljivanje neobičnih valova i njihove značajke utvrdili smo da ti valovi nisu tako rijetka pojava kako se obično pretpostavlja te da se javljaju ne samo za olujnih nevremena nego i kad su vremenske prilike stabilne. Premda uobičajena spektralna analiza daje neke informacije o neobičnim valovima, pristup baziran na pretpostavci stacionarnosti slučajnog procesa očito ne može cjelovito dokumentirati jedan takav lokalizirani nestacionarni proces kakav predstavljaju neobični valovi
Neobični valovi u akvatoriju Campos (Brazil)
Freak waves occur abundantly in Campos Basin, located on the northeast coast of Rio de Janeiro, Brazil in the South Atlantic Ocean. This surprising and unexpected discovery was made from a search of the time-series data of wave measurements recorded in the Campos Basin from 1991 to 1995. In a study on the occurrence of freak waves and their relevant properties, we have also found that freak waves are not of rare occurrence as conventionally presumed, and they occur not only during storm conditions but also during fair weather states as well. While the conventional approach of spectrum analysis provides some weak inference of freak wave effects, the basically stationary random process approach is clearly incapable of contending with the localized non-stationary process of freak wave occurrences.Neobični se valovi često pojavljuju u akvatoriju Campos, sjeveroistočno od Rio de Janeira (Brazil) u južnom Atlantiku. To iznenađujuće i neočekivano otkriće načinjeno je na osnovi vremenskih nizova prikupljenih valomjerima u akvatoriju Campos u
razdoblju od 1991. do 1995. godine. Istražujući pojavljivanje neobičnih valova i njihove značajke utvrdili smo da ti valovi nisu tako rijetka pojava kako se obično pretpostavlja te da se javljaju ne samo za olujnih nevremena nego i kad su vremenske prilike stabilne. Premda uobičajena spektralna analiza daje neke informacije o neobičnim valovima, pristup baziran na pretpostavci stacionarnosti slučajnog procesa očito ne može cjelovito dokumentirati jedan takav lokalizirani nestacionarni proces kakav predstavljaju neobični valovi
Avaliação, educação e comunicação do risco sísmico no contexto das escolas do Algarve
Tem sido observado, um pouco por todo o mundo, que as populações não têm consciência do risco sísmico dos edifícios onde habitam, e que possuem espectativas irrealistas sobre o comportamento dessas construções. A perceção generalizada é que as habitações irão ficar intactas após um sismo moderado ou destruidor, desde que estas tenham sido corretamente projetadas e construídas, de acordo com as normas vigentes. Contudo, os edifícios somente são projetados para garantir a salvaguarda da vida humana, e não para a salvaguarda do património em si, podendo até não ser economicamente viável a sua reparação. Além disso, um sismo moderado poderá causar danos moderados ou severos, principalmente a nível não-estrutural, afetando assim o funcionamento das instalações por tempo indeterminado. Por outro lado, é importante promover a educação e informação das populações para contribuir para o aumento da resiliência das sociedades a estes fenómenos.
Neste contexto, foi desenvolvida uma plataforma informática no âmbito do projeto de investigação PERSISTAH (Projetos de Escolas Resilientes aos SISmos no Território do Algarve e de Huelva), que possibilita a realização de avaliações de segurança sísmica dos edifícios das escolas do primeiro ciclo do ensino básico existentes no Algarve, recorrendo a modernas técnicas de análise estrutural. Usando esta ferramenta, é possível verificar qual o grau de dano provável de um edifício de uma escola, quer seja para um qualquer cenário de ocorrência de um sismo, ou simplesmente no contexto da verificação dos níveis de segurança estabelecidos nas normas NP EN 1998-1:2010 e NP EN 1998-3:2017. Estão a ser criados documentos direcionados para técnicos da área da construção, para aprendizagem das referidas metodologias, assim como relativas ao uso de técnicas de reabilitação sísmica.
Em paralelo, também foram desenvolvidos instrumentos para aumentar a resiliência sísmica da população estudantil, designadamente o Projeto Educativo “Porquê que o chão se move?”, com atividades e material pedagógico para a educação e comunicação do risco sísmico, e o “Guia Prático da Escola Resiliente aos Sismos”, que também visam a implementação de medidas de redução do risco sísmico não-estrutural.info:eu-repo/semantics/publishedVersio
New adsorbers for the removal of genotoxic impurities from active pharmaceutical ingredients
Active pharmaceutical ingredients (APIs) available in the market are mostly synthesized, in organic solvent media, using highly reactive molecules that may be present in the final product as genotoxic impurities (GTIs). These compounds have the ability to react with DNA, preventing its normal replication, resulting in an associated carcinogenic risk, becoming an increasing concern from pharmaceutical companies and regulatory authorities [1]. Although it is desirable to avoid the use of GTIs in the manufacture of APIs, this is not always possible. Therefore, there is a call to develop simple, robust and economical routes to remove GTIs to limits below the Threshold of Toxicological Concern (1.5 µg/day) [2]. Such adsorbents should be highly selective to reach ultra-low GTI levels with minimal API losses and compatible with organic solvents where the API synthesis takes place [3].
Herein we report two different strategies for the development of new adsorbing materials designed for selective removal of GTIs from API organic solvent solutions. These new materials are: i) molecular imprinted polymers (MIPs), in the particular case designed for removal of an aromatic amine GTI, 4-dymethylaminopyridine) [4]; and ii) a novel functionalized polymer consisting on polybenzimidazole (PBI) modified with a DNA base (PBI-adenine). PBI-Adenine is designed to have a high affinity for a broad range of DNA alkylating agents mimicking the DNA-GTI adduct formation that takes place in vivo [5,6]. These platforms proved to be robust materials being able to remove, in a single stage, more than 95% of the GTIs from organic solvent API mixtures. Both approaches, meet the pharmaceutical industry challenges, by opening new horizons for the use of these adsorbers as a complement to the existing operation units as MIPs, as well as their assembling as membranes for organic solvent nanofiltration (OSN) derived from PBI.
References
[1] Teasdale A. et al., Org. Process Res. Dev. 17, 2013, 221-230.
[2] EMEA Guidelines on the “Limits on Genotoxic Impurities”, EMEA/CHMP/QWP/251344/2006, 2006.
[3] Székely G. et al., Green Chem. 15, 2013, 210-225.
[4] Esteves T. et al., Sep. Purif. Technol. 163, 2016, 206-214.
[5] Ferreira F. C.; Esteves T.; Vicente A. I.; Afonso C. A. M., “Polímeros polibenzimidazolo com cadeia espaçadora funcionalizada e seu método de obtenção para remoção de impurezas genotóxicas.” Patent request Nº 109480, with priority date of 22 June 2016.
[6] Vicente A. I. et al., Chem. Mat., 2016, under preparation.
Acknowledgements: We thank financial support from Fundação para a Ciência e Tecnologia (FCT) through the Project SelectHost (PTDC/QEQ-PRS/4157/2014) and iBB-Institute for Bioengineering and Biosciences (UID/BIO/04565/2013), from Programa Operacional Regional de Lisboa 2020 (Lisboa-01-0145-FEDER-007317). We thank to Hovione PharmaScience Ltd for supplying the API and technical know-how
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