A study of a single droplet impinging onto a sloped surface: Jet-Fuel and Biofuel mixtures

The present study experimentally investigated droplets impinging on a sloped aluminum surface. In these experiments, the droplet is spherical throughout the trajectory where the gravitational acceleration and movement of the droplet have the same direction, which leads to unique phenomena. Considering an oblique impact, the droplet collides with a certain angle, and the impact velocity is composed of normal and tangential components to the surface that vary with the impact height. Four fluids were tested: 100% Jet-Fuel, 75% Jet-Fuel/ 25% HVO, 50% Jet-Fuel/ 50% HVO and H2O (pure water) as a reference. The mixtures were a combination of a conventional Jet Fuel (Jet A-1) and a biofuel (HVO – Hydroprocessed Vegetable Oil), more specifically NExBTL. When a droplet impacts onto an inclined surface, its shape is distorted and it can spread or splash asymmetrically relatively to the point of impact, affecting the advancing and receding contact angle. Therefore, several geometric parameters were measured and compared for the different fluids and incident angles. The incident angles influence the spreading velocity on the upper and lower side. The spreading velocity was analyzed, allowing a better understanding of the dynamic behavior of each side. The spread factor, which corresponds to the distance between the lower and upper edges normalized by the initial droplet diameter, was compared to the Weber number (We) which is a proper indicator for the drop deformation. The variation of incident angles and impact velocity promotes a different droplet movement and asymmetry in phenomena that are also evidently influenced by the gravity role.info:eu-repo/semantics/publishedVersio

Experimental Investigation Of Disruptive Burning Phenomena On Nanofuel Droplets

The transport sector plays a crucial aspect in society and economic evolution. However, improper energy management has negatively impacted health and the environment. Thus, the use of sustainable and green fuels in the aeronautical industry has been implemented due to environmental concerns and the depletion of fossil fuels. The introduction of biofuels, a renewable energy source in the transportation sector, has shown advantages in terms of pollutant reduction. Recently, the addition of nanoparticles in the combustion of biofuel has been studied with the purpose of enhancing its combustion characteristics. Consequently, the present work evaluates nanofuel single droplet in a falling droplet method. In this way, the fiber suspension effect was neglected, and droplets in a size of 250 μm were evaluated. To this end, a comparison between pure biofuel and a nanofuel at two furnace temperatures (T = 800 ºC and T = 1000 ºC) was performed. The results reveal that disruptive burning phenomena occur when aluminum nanoparticles are added to the biofuel. Consequently, a micro-explosion determines the end of the droplet lifetime, mainly affected by the furnace temperature.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

A fruit snack including grape and tomato pomaces: assessment of the effect of temperature on drying characteristics and quality during storage

info:eu-repo/semantics/publishedVersio

Integrated approach on solar drying, pilot convective drying and microstructural changes

Solar drying of foods is an old technique, still used nowadays. Nevertheless, the mathematical approach of the complex phenomena involved is not completely integrated. Drawbacks appear in modelling heat transport, specially related to the huge variability of meteorological factors. The great dependence of the heat and mass transfer model parameters on water content is also frequently forgotten. Macroscopic changes (e.g. shrinkage) that occur during drying processes, are usually not considered in mass transfer equations, also affecting the predictive ability of the models. The objective of this work was to develop the mathematical basis and considerations for integrating heat and mass transfer phenomena, taking into consideration macroscopic changes and their correlation to changes at microscopic level (e.g. cellular shrinkage), that might occur during solar drying of grapes

The influence of aluminium particles in a Hydroprocessed Vegetable Oil combustion

The present work experimentally investigates single droplet combustion to understand the effect of aluminum particles when added to a biofuel. Experiments are carried out in a drop tube furnace to evaluate the influence of size and concentration of the aluminum particles. Two different sizes (40 nm and 5 μm) and two concentrations (0.5 and 1.0 wt.%) are studied at 1000 °C. The addition of aluminum particles improves biofuel combustion. Decreasing the particle size and increasing the particle concentration leads to a significant enhancement in the burning rate compared to the pure HVO. Micro-explosions are detected at the end of droplet lifetime when particles are added to biofuel.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Aerobic physical exercise versus dual-task cognitive walking in cognitive rehabilitation of people with stroke: a randomized clinical trial

Introduction: Stroke is a neurological deficit caused by an acute focal injury to the central nervous system due to vascular injury that can result in loss of neurological function, lasting brain damage, long-term disability and, in some cases, death. The literature reports that aerobic physical exercise, as well as dual-task cognitive walking, are used for the cognitive recovery of people with stroke. We aimed to assess whether aerobic physical exercise influences post-stroke cognitive recovery, namely performance on selective and sustained attention. We tested the hypothesis that post-stroke aerobic physical exercise leads to more significant gains than post-stroke dual-task cognitive walking. Methods: We used a Randomized Clinical Trial, single-blind, parallel group, to verify the existence of differences between two groups. A total of 34 patients with subacute to chronic stroke were divided into two groups to train three times a week for 12 weeks: the aerobic physical exercise (PE) group engaged in 20 min on a treadmill, 20 min on a stationary bicycle and 5 min on a desk bike pedal exerciser per session; the dual-task (DT) gait exercise group walked for 45 min while simultaneously performing cognitive tasks per session. All participants were assessed on cognitive functioning with the Mini-Mental State Examination (MMSE) and d2 Test of Attention before acute interventions and post interventions. We have also applied a Visual Analog Scale to monitor the participants’ perceived difficulty, pre-, post-acute, and post-chronic interventions. Participants also responded to a Borg Scale of perceived exertion following the acute and the final session of chronic training. Results: A mixed model ANOVA revealed a significant interaction effect with a large effect size for most of the cognitive variables under study. The variables associated with the d2 Test of Attention showed significant differences between the groups, mainly from T0 to T2. Also for MMSE, an ANOVA revealed a significant interaction effect with significant improvements from T0 to T2. Our results strongly suggest that aerobic physical exercise is more beneficial than dual-task cognitive-gait exercise since in the PE group, cognitive attention scores increase, and cognitive impairment and perception of exertion decrease, compared to the DT group. Conclusion: These findings support that PE provides more significant benefits for patients post-stroke when compared to DT.info:eu-repo/semantics/publishedVersio

Cognitive benefits of exercise: is there a time-of-day effect?

It is well established that physical activity benefits cognition. Further, the time of day one engages in physical activity has been suggested to influence cognition. Here, we aimed to understand if there is a time-of-day effect (morning or afternoon) of physical activity on cognition, i.e., if exercising in the morning or afternoon might bring greater cognitive benefits. A total of 56 participants were allocated to one of two groups with the same baseline cognitive performance as well as fitness level (International Physical Activity Questionnaire—IPAQ): 27 to the morning intervention (M) group; and 29 to the afternoon intervention (A) group. In both groups, the participants engaged in an intermittent recovery test (Yo-yo), 4 times a week for 12 weeks. All participants were assessed with the d2 Test of Attention and the Borg scale of perceived exertion pre- and post- acute and chronic intervention. After the first bout of exercise and after 12 weeks, we observed cognitive improvements both in the M and A groups. Surprisingly, we do not find differences between the time of day regarding cognitive benefits. Our results do not support the existence of a time-of-day effect for the attentional cognitive benefits of exercise.info:eu-repo/semantics/publishedVersio

Cyber-Detective: a game for cyber crime prevention

Technologies are increasingly becoming a part of the daily lives of younger generations and with no supervised usage of these technologies, teenagers are exposed to various threats. To raise the awareness of teenagers in ages between 14 and 17 years old, and to provide a methodological tool for educational professionals working with the young and even for enforcement professionals investigating the cyber cases, an educational game about cyber security was designed and prototyped. A detective game was devised, where the player takes the role of a detective to investigate a cyber crime. To solve the case, the player must play several mini-games, where each one explores a specific thematic about cyber security. For example, in the prototype, the situation that the detective needs to solve is a ransomware case. The situations are introduced by a tridimensional animation, which appears as a cutscene introducing the game scene. It is an animation where one can see a teen trying to buy a pair of sneakers online and after downloading an application suggested in the website, his mobile phone is locked. Thus, he decides to search help from the police, where the detective will try to solve the problem. For that, the player has to solve several mini-games about sharing information in social networks, phishing and the importance of creating strong passwords. In these mini-games the player makes decisions and learns based on that, i.e., at the end of each mini-game each decision is explained to the player regardless of the choice being correct or incorrect. This way, the player is always informed of the various situations that can occur based on their behavior/decisions online. The prototype was developed for mobile devices and some preliminary tests were performed with teenagers. The tests showed that the teenagers improved their cyber security knowledge after playing the game. A cyber security educational game can be used as a tool for younger generations because it uses the technologies that are part of their daily lives and can contribute to the growing of their cyber security awareness. In the future, we hope to develop the full game, where other thematic will be included, namely, talking with strangers in social networks, dangers related with the webcam and microphone, online piracy and cyber bullying.info:eu-repo/semantics/publishedVersio