Abstract
Nowadays, meaningful learning takes a central role in science education and is based in mental models that allow the representation of the real world by individuals. Thus, it is essential to analyse the student's mental models by promoting an easier reconstruction of scientific knowledge, by allowing them to become consistent with the curricular models presented in the classroom. In this context, the study aims to examine, through the application of a diagnostic instrument (Two-Tier Diagnostic Test), what students consider to be the seismic effects on soils and buildings, to analyse and to compare their mental models about some of these issues related to seismology, applying a questionnaire to 52 students from a Portuguese University attending an undergraduate degree in Geology and a master course in Biology and Geology teaching. The analysis of the data allowed concluding that undergraduate students have more inconsistent mental models than master students, mainly concerning the factors which influence the seismic risk, such as hazard and vulnerability, and the soils characteristics which influence the intensity of earthquakes. During their academic formation in the university, teachers present some curricular models to students which allow them to reconstruct their mental models and turn them scientifically consistent, enhancing the educational implications of this study that points to the need for teachers to be aware of the importance of the diagnosis of the students' mental models and to promote meaningful learning and scientific literacy autonomously and dynamically.

Abstract
Actuators based on electroactive polymers are increasingly used in applications including microelectronic devices and artificial muscles, demanding low voltage operation and controllable switching response. This work reports on the preparation of electroactive actuators based on poly(vinylidene fluoride) (PVDF) composites with 10, 25, and 40 wt% N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulfonyl)imide ([N-1 1 1 2(OH)][NTf2]) and 1-Ethyl-3-methylimidazolium Ethylsulfate ([C(2)mim][C2SO4]) ionic liquids (ILs) prepared by solvent casting. Independent of the IL type, its presence leads to the crystallization of PVDF in the piezoelectric beta-phase. The degree of crystallinity and electrical conductivity of the samples strongly depends on ILs type and content. The highest electrical conductivity was found for PVDF/IL composites with 40 wt% of [N-1 1 1 2(OH)][NTf2]. The strain displacement and bending of the PVDF/IL composites were evaluated as a function of IL type and content under applied peak voltages of 2.0, 5.0, and 10.0 V at a frequency of 10 mHz. Strain displacement of the actuators depends more on IL content than on IL type, and the best strain bending response was found for the PVDF/IL composite with 25 wt% of [N-1 1 1 2(OH)][NTf2] at 5.0 V. Further, it is shown that [C(2)mim] [C2SO4]/PVDF composites do not show cytotoxic behavior, being suitable for biomedical applications.

Abstract
Low voltage actuators based on poly(vinylidene fluoride) (PVDF) with 10, 25 and 40% 1-hexyl-3-methylimidazolium chloride ([C(6)mim][Cl]) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(6)mim][NTf2]) are prepared by solvent casting in order to evaluate the effect of anion size in the bending properties. Independently of the ionic liquid type and content, its presence leads to the crystallization of PVDF in the beta-phase. The addition of ionic liquid into the polymer matrix decreases significantly its degree of crystallinity and the elastic modulus. It is also confirmed the good miscibility between PVDF and IL, determined by the interaction of the CF2 groups from the PVDF chains with the imidazolium ring in the ionic liquid (IL). The AC conductivity of the composites depends both on the amount of ionic liquid content and anion size. The bending movement of the IL/PVDF composites is correlated to their degree of crystallinity, mechanical properties and ionic conductivity value and the best value of bending response (0.53%) being found for IL/PVDF composite with 40 wt of [C(6)min][Cl] at an applied voltage of 10 V square signal.

Abstract
The future of robotics is now trending for home servicing. Nursing homes and assistance to elder peopleare areas where robots can provide valuable help in order to improve the quality of life of those who need it most. Calling a robot,for a person of age,can be a daunting task if the voice is failing and any resort to battery operated devices failsto comply. Using a simple mechanical apparatus,such as aClick trainerfordogs, a person can call a robot by pressing thebutton of a powerless device. The high pitch sound produced by this device can be captured and tracked down in order to estimate the person’s location within a room. This paper describes a method that provides good accuracy and uses simple and low cost technology,in order to provide an efficient positional value for an assistance robot to attend its caller. The robot does not need to search for the person in aroom as it can directly travel towards the Click’s sound source.

Abstract
In order to achieve underwater acoustic high data-rate and real time communications, it is essential to implement a system that operates both at high and wideband frequencies using digital modulations. Therefore, to reduce the time and cost of developing acoustic communications an emulator of a physical layer model was implemented, allowing to test in real time the performance of digital modulations. The model was composed of an emitter transducer, a hydrophone and the subaquatic medium and was integrated in a Field Programmable Gate Array (FPGA) in order to emulate the physical layer in the acoustic modem testing. The emitter transducer and the hydrophone models were designed to meet real prototype characteristics. The system prototype was implemented in order to compare the experimental trials results with those obtained in emulator, emulating the transmission of acoustic signals, using different types of digital modulations. The system was tested using Binary Phase-Shift Keying (BPSK), Binary Frequency Shift keying (BFSK) and Binary Amplitude Shift Keying (BASK) modulations with a 1 MHz carrier frequency resulting in a data rate of 125 kbps. It was verified that the implemented model represents a suitable approximation to the real subaquatic communication channel, allowing the evaluation of digital acoustic communications.

Abstract