Study of fundamental control concepts through interactive learning objects

Information technology has contributed significantly to the renewal of teaching methodologies used in control systems teaching. Computer applications are becoming very popular as a support in traditional lectures and as self-learning tools. This paper describes an on-going project which tries to develop a suite of interactive learning objects composed by graphical interactive applications plus simple learning cards to cover the complete contents of an introductory control system course.Postprint (published version

Coarse-grain molecular dynamics simulation framework to unravel the interactions of surfactants on silica surfaces for oil recovery

A coarse-grained molecular dynamics (CG-MD) framework, based on the MARTINI 3.0 model, was developed to characterise the interactions between surfactants and oil-silica substrates to resemble chemical enhanced oil recovery (EOR) processes. Previous computational studies, at the atomistic scale, addressed interactions between surfactants and oil over diverse surfaces. Even though simulations provided significant information involved throughout different stages of oil extraction from surfaces, atomistic scale simulations fail when approaching the time and size scale required to address the surfactant phase behaviour that can also impact the oil detachment. Our coarse-grained model aims to overcome the lack of computer approaches that can tackle the surfactant self-assembly and the formation of ordered structures in the removal of oil from silica substrates. A new MARTINI 3.0 coarse-grain framework to model silica surfaces and aqueous solutions of CiEj and C16TAB surfactants is presented. Coarse-grained simulations entailing a silica surface, covered by dodecane or eicosane were brought in contact with aqueous solutions of C16TAB and four nonionic CiEj (C8E6, C8E12, C12E6, C16E12) surfactants to resemble EOR processes with a size/time scale several orders of magnitude larger than previous simulations. The impact of concentration and hydrophilic-lipophilic balance (HLB) of surfactants on the detachment of dodecane and eicosane from the silica surface was evaluated by visual inspection of the simulation snapshots and the evolution of the solvent accessible surface areas (SASA). In contrast with previous atomistic simulations, nonionic surfactants seem the best candidates for an optimal oil removal from silica-based surfaces whereas the presence of charged moieties hinders the process. Diluted nonionic CE aqueous solutions were shown to be the most effective solutions, unlike more concentrated ones. When compared with dodecane, eicosane was less prone to be removed from the silica surface due to the increased alkyl chain length. Our study demonstrates that not only the surfactant nature but also the phase behaviour, clearly impact the detachment of oil from silica surfaces. This is an important aspect to consider for a proper choice of surfactants in EOR processes, that is only attainable through a coarse-grained framework.publishe

Mass Spectrum of Strings in Anti de Sitter Spacetime

We perform string quantization in anti de Sitter (AdS) spacetime. The string motion is stable, oscillatory in time with real frequencies $\omega_n= \sqrt{n^2+m^2\alpha'^2H^2}$ and the string size and energy are bounded. The string fluctuations around the center of mass are well behaved. We find the mass formula which is also well behaved in all regimes. There is an {\it infinite} number of states with arbitrarily high mass in AdS (in de Sitter (dS) there is a {\it finite} number of states only). The critical dimension at which the graviton appears is $D=25,$ as in de Sitter space. A cosmological constant $\Lambda\neq 0$ (whatever its sign) introduces a {\it fine structure} effect (splitting of levels) in the mass spectrum at all states beyond the graviton. The high mass spectrum changes drastically with respect to flat Minkowski spacetime. For $\Lambda\sim \mid\Lambda\mid N^2,$ {\it independent} of $\alpha',$ and the level spacing {\it grows} with the eigenvalue of the number operator, $N.$ The density of states $\rho(m)$ grows like \mbox{Exp}[(m/\sqrt{\mid\Lambda\mid}\;)^{1/2}] (instead of \rho(m)\sim\mbox{Exp}[m\sqrt{\alpha'}] as in Minkowski space), thus {\it discarding} the existence of a critical string temperature. For the sake of completeness, we also study the quantum strings in the black string background, where strings behave, in many respects, as in the ordinary black hole backgrounds. The mass spectrum is equal to the mass spectrum in flat Minkowski space.Comment: 31 pages, Latex, DEMIRM-Paris-9404

PATs Behavior in Pressurized Irrigation Hydrants towards Sustainability

[EN] Sustainability and efficiency in irrigation are essential in the management of the water- energy-food nexus to reach the Sustainable Development Goals in 2030. In irrigation systems, the reduction of energy consumption is required to improve the system efficiency and consequently the sustainability indicators of the water network. The use of pumps working as turbines (PATs) has been a feasible solution to recover the excess of energy where pressure reduction valves are installed. This research demonstrates the use of PATs under steady and unsteady conditions by analyzing the application in a real irrigation networks located in Vallada (Valencia, Spain). The study shows the possibility of recovering 44 MWh/year using PATs installed upstream of the irrigation hydrants. The real behavior of the PAT operation in a stand¿alone recovery energy solution allowed analysis of the flow, head and efficiency variation as a function of the rotational speed, as well as the minimum capacitance to self-excite the generator and the resistive load of the electrical circuit. The PAT limit is examined in terms of the overpressure induced by a fast closure manoeuvre of hydrants, and the runaway conditions due to the disconnection from the electrical load.This work was supported by FCT-Foundation for Science and Technology, through CERIS, IP, and IDMEC, under LAETA, project UIDB/50022/2020. This research is also supported by the Program to support the academic career of the faculty of the Universitat Politècnica de València 2019/2020 in the project A STEP AHEAD IN SUSTAINABILITY OF WATER SYSTEMS FOR THE ENERGY TRANSITION IN COMMUNITIES of the Modesto Pérez- Sánchez. The authors wish to thank the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA Fluids PROGRAMME 2014-2020 and CERIS, the Hydraulic Laboratory, for the support in the conceptual developments and the experiments on PATs.Pérez-Sánchez, M.; Fernandes, JF.; Costa Branco, P.; López Jiménez, PA.; Ramos, HM. (2021). PATs Behavior in Pressurized Irrigation Hydrants towards Sustainability. Water. 13(10):1-17. https://doi.org/10.3390/w13101359S117131

Safety culture maturity assessment for mining activities in South America

BACKGROUND:Health and safety is a crucial issue in the mining industry due to the implication of accidents in the sector. OBJECTIVE:This study determines the safety culture characteristics in several mining activities from South America. METHODS:A survey of the safety culture maturity has been done by means of 24 questions regarding the type of activity, number of employees and safety culture characteristics of the activity: information of accidents and incidents, organizational structure to deal with information, involvement of the company in health and safety issues, the way it communicates accidents and incidents and commitment of the company towards health and safety. RESULTS:The questionnaire was completed by 62 managers from Bolivia, Peru and Colombia. Results show different behaviors depending on the type of company, Artisanal or Large-Scale Mines, ASM and LSM respectively. LSM show a level of maturity according to the size of the company, while ASM does not have a clear trend in terms of size, even though there is a relationship between employees and safety culture maturity. In addition, a remarkable difference can be seen between activities with and without continuous improvement systems implemented. CONCLUSIONS:Large scale mining improves their level of safety culture as the size of the company increases, because procedures and control systems are implemented. Cooperatives or small companies also achieve substantial gains when they introduce similar systems

What can metazoan parasites reveal about the taxonomy of Scomber japonicus Houttuyn in the coast of South America and Madeira Islands?

The metazoan parasites of four populations of the chub mackerel Scomber japonicus were analysed from two localities in the Atlantic Ocean (Madeira Islands, Portugal, and Rio de Janeiro, Brazil) and two localities in the Pacific Ocean (Callao, Peru, and Antofagasta, Chile), collected during 2002 and 2003. A total of 373 fish specimens were studied and 34 metazoan parasite species were obtained. Parasites identified from the populations of chub mackerel studied could be separated into three categories: parasites with a wide distribution, present in the Pacific and Atlantic, parasites proper of the Pacific Ocean and parasites proper of the Atlantic Ocean. The analyses of some highly specific parasites of the genus Scomber (i.e. monogeneans of the genus Kuhnia and didymozoid digeneans) strongly suggest the need for a revision of the taxonomic status of chub mackerels from the Atlantic and Pacific coast of America. The results demonstrated the usefulness of parasites as adequate tools to clarify the taxonomic status of their hosts.We thank R. Poulin (University of Otago, New Zealand) for reading and commenting on an early draft of the manuscript. J.L.L. was supported by a fellowship (N° 200906-2005.4) of the Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo´ gico (CNPq) of Brazil for postdoctoral research in the Department of Zoology at the University of Otago, New Zealand. G. Costa was supported by Portuguese Foundation of Science and Technology, programme POCTI.info:eu-repo/semantics/publishedVersio

Effects of two different training programs with same workload on throwing velocity by experienced water polo players

To investigate the effects of two different strength-training programs with the same workload (impulse) on throwing velocity in water polo, 30 water polo players (M age = 17.1 yr., SD = 4.9; M mass = 71.2 kg, SD = 14.7; M height = 1.75 m, SD = 0.09 m) were randomly divided in two groups based upon throwing performance with water polo ball. The medicine-ball training group performed 3 x 6 reps with a 3-kg medicine ball, while the combination training group completed 1 x 9 repetitions with the 3-kg medicine ball, followed by 3 x 14 repetitions with a water polo ball. Both groups trained eight weeks twice per week in addition to their regular water polo training. Throwing velocity was measured with a Doppler radar gun before and after the training period. Testing included throws with a water polo ball on land and in water, as well as with 1-kg and 3-kg medicine balls on land. Statistically significant increases were found in mean peak throwing velocity with the water polo, 1-kg, and 3-kg medicine balls after training. No differences between the groups were found, except in throwing velocity with water polo on land, with a statistically significantly larger increase for the combination training group (+7.6%) than the medicine-ball training group (+3.4%). These findings indicate that after training with the same workload (impulse), increases in throwing velocity in water polo are similar and suggesting workload may be a critical variable for training results.info:eu-repo/semantics/publishedVersio

Tactical Voting in Plurality Elections

How often will elections end in landslides? What is the probability for a head-to-head race? Analyzing ballot results from several large countries rather anomalous and yet unexplained distributions have been observed. We identify tactical voting as the driving ingredient for the anomalies and introduce a model to study its effect on plurality elections, characterized by the relative strength of the feedback from polls and the pairwise interaction between individuals in the society. With this model it becomes possible to explain the polarization of votes between two candidates, understand the small margin of victories frequently observed for different elections, and analyze the polls' impact in American, Canadian, and Brazilian ballots. Moreover, the model reproduces, quantitatively, the distribution of votes obtained in the Brazilian mayor elections with two, three, and four candidates.Comment: 7 pages, 4 figure

Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning

[EN] The use of pump working as turbine (PAT) was identified by many researchers as a way to improve the energy efficiency in the water systems. However, the majority of the researches consider the hydraulic machine connected to the electrical grid, which may not fit best when these recovery systems are located in rural or remote areas. To improve the efficiency in these recovery systems for rural areas, this research contributes for a further study and optimization of the off-grid PAT systems with induction generators. The current manuscript proposes a methodology to obtain the best efficiency of the PAT-SEIG (Self-Excited Induction Generator) system when operating under different speeds and loads. For these systems, the selection of capacitors for the SEIG is critical to maximizing the energy efficiency. A methodology is proposed to estimate and select the correct SEIG model parameters and, thus, compute the best capacitor values to improve the PAT-SEIG energy efficiency. Special attention is given to the impact the SEIG parameters have in the efficiency of the recovery system. The accuracy of the analytical model improved, reducing the error between analytical and experimental results from 50.8% (for a model with constant parameters) to 13.2% (with parameters changing according to the operating point of the system). These results showed an increase of the overall PAT system efficiency from 26% to 40% for the analyzed case study.This work was supported by FCT, through IDMEC, under LAETA, project UID/EMS/50022/2019 and the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA PROGRAMME 2014-2020 and CERIS (CEHIDRO-IST), the Hydraulic Laboratory, for experiments on PATs.Fernandes, JF.; Pérez-Sánchez, M.; Ferreira, F.; López Jiménez, PA.; Ramos, HM.; Costa Branco, P. (2019). Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning. Energy Conversion and Management. 183:391-405. https://doi.org/10.1016/j.enconman.2019.01.016S39140518

Conjunctival vaccination against Brucella ovis in mice with mannosylated nanoparticles

The use of sub-unit vaccines can solve some drawbacks associated with traditional attenuated or inactivated ones. However, in order to improve their immunogenicity, these vaccines needs to be associated to an appropriate adjuvant which, adequately selected, may also offer an alternative pathway for administration. The aim of this work was to evaluate the protection offered by the hot saline complex extracted from Brucella ovis (HS) encapsulated in mannosylated nanoparticles (MAN-NP-HS) when instilled conjunctivally in mice. Nanoparticles displayed a size of 300 nm and the antigen loading was close to 30 μg per mg nanoparticle. Importantly, encapsulated HS maintained its protein profile, structural integrity and antigenicity during and after the preparative process of nanoparticles. The ocular immunization was performed on BALB/c mice. Eight weeks after vaccination animals were challenged with B. ovis, and 3 weeks later, were slaughtered for bacteriological examinations. Animals immunized with MAN-NP-HS displayed a 3-log reduction in spleen CFU compared with unvaccinated animals. This degree of protection was significantly higher than that observed for the commercial vaccine (Rev1) subcutaneously administered. Interestingly, the mucosal IgA response induced by MAN-NP-HS was found to be much more intense than that offered by Rev1 and prolonged in time. Furthermore, the elicited IL-2, IL-4 and γ-IFN levels showed good correlation with the degree of protection. On the other hand, biodistribution studies in animals were performed with nanoparticles labelled with either 99mtechnetium or rhodamine B isothiocyanate. The biodistribution revealed that, after instillation, MAN-NP-HS moved from the palpebral area to the nasal region and, the gastrointestinal tract. This profile of distribution was different to that observed for free 99mTcO4− colloids, which remained for at least 24 h in the site of administration. In summary, mannosylated nanoparticles appear to be a safe and suitable adjuvant for conjunctival vaccination