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Knock remains one of the main limitations for increasing the efficiency in spark-ignition engines. The use of certain alcohol–gasoline blends is an effective way to either mitigate or eliminate knock, allowing the use of higher compression ratios, therefore increasing the efficiency of spark-ignition engines. Methanol and ethanol are alcohols commonly employed for reducing knock, due to their higher octane number and vaporization heat value. Major attention is being paid recently to butanol and its blends with gasoline since they present similar characteristics to gasoline; however, it was found to be the least knock resistant among the three fuels. In the present work, a comparison between the knock performance of methanol–gasoline, ethanol–gasoline and butanol–gasoline blends is carried out, by volume concentrations up to 20 v/v%. This comparison is made in terms of knock intensity and knock probability. Tests are performed in a single-cylinder, variable-compression ratio, Cooperative Fuel Research engine equipped with port fuel injection system, facilitating the comparison against future results obtained by similar experimental facilities. Results obtained allow to reach meaningful conclusions about the capacity of each blend to mitigate knock.

In the last few years, increasing concern about the harmful effects of the use of fossil fuels in internal combustion engines has been observed. In addition, the limited availability of crude oil has driven the interest in alternative fuels, especially biofuels. In the context of spark ignition engines, bioalcohols are of great interest owing to their similarities and blend capacities with gasoline. Methanol and ethanol have been widely used, mainly due to their knocking resistance. Another alcohol of great interest is butanol, thanks to its potential of being produced as biofuel and its heat value closer to gasoline. In this study, a comparative study of gasoline–alcohol blend combustion, with up to 20% volume, with neat gasoline has been carried out. A single-cylinder, variable compression ratio, Cooperative Fuel Research-type spark ignition engine has been employed. The comparison is made in terms of fuel conversion efficiency and flame development angle. Relevant information related to the impact in the combustion process of the use of the three main alcohols used in blends with gasoline has been obtained.

This work studies the viability of diesel-biodiesel-ethanol blends for compression ignition engines. Blends are prepared with a fraction of 5%, 10% and 20% of ethanol and a fraction of 10%, 20%, 30% and 40% of biodiesel in volume basis. Stability of such blends was first studied, and assessed by visually determining the phase separation 96 h after the blend was made. DB20E5, DB30E5, DB40E5, DB30E10, DB40E10 DB30E20 and DB40E20 blends maintain 0% phase separation after the test, which indicates that biodiesel acts as a surfactant and allows ternary blends being stable. For stable blends, properties (density, kinematic viscosity and surface tension) were determined. Finally, from those stable blends which properties stand within the allowed ranges by the EN-590 standard, three of them were injected in a constant volume chamber and its spray macroscopic parameters were experimentally determined. Blends with higher density show an increased spray tip penetration and those with less surface tension and kinematic viscosity show more cone angle. We conclude that DB30E10 is the blend that best air blending capacities exhibits from those with stable mixing and allowed physical properties.

Current regulations restrict NOx and particulate emissions (PM) produced by new vehicles. One solution for reducing these emissions, mainly PM, is focused on the use of cleaner fuels. In this sense, the smoke point test (SP) has been proved to be a fast tool when comparing the sooting tendency of fuels. As manual SP determination can imply an error owing to the inherent uncertainty of visual flame observation, the updated ASTM D1322-18 has stated that the new commercial equipment SP10 Automated Smoke Point Analyser is the reference for SP determination. However, its high cost has motivated this work where a vision based algorithm for automated determination of SP without wick-fed modifications is proposed. Experimental results demonstrate the accuracy and repeatability of the proposed method.

[Abstract] Introduction and hypothesis: The effect of different abdominal contractions on the position of pelvic organs in parous women during postpartum exercises has not been sufficiently assessed. The aim of this study was to evaluate the displacement of the bladder base (BB) during different pelvic floor and abdominal contractions in parous women compared to nulliparous women. We hypothesised that abdominal and perineal contractions will produce a disparate effect on the position of the BB between groups. Methods: Cross-sectional study including a convenience sample of 63 volunteers (35 nulliparous vs. 28 postpartum women). Transabdominal ultrasound was used in mode B to image the displacement of the BB. The protocol included six different pelvic floor and abdominal contractions commonly used in postpartum rehabilitation. Results: The BB elevated significantly more in the postpartum group compared to nulliparous women when performing submaximal contraction of pelvic floor and transversus abdominis muscles simultaneously with axial elongation of the back (0.93 ± 0.55 cm in parous women vs. 0.66 ± 0.46 cm in nulliparous women). In contrast, the BB was found to descend significantly during a curl-up contraction in both groups (0.93 ± 0.55 cm in parous women vs. 0.66 ± 0.46 cm in nulliparous women). Conclusions: The overall results of this study showed that perineal and superficial abdominal contractions produced different immediate effects compared to deep abdominal contractions on the displacement of BB in parous and nulliparous women. Further research is required to assess the long-term effects of these contractions.

The propulsive forces and instantaneous power that are generated by a swimmer have a great influence on the swimming performance. This works presents a new device, called SwimOne, for measuring propulsive force and estimating the instantaneous power of the swimmer. In addition, the detailed prototype is able to exert a customizable opposition force to the swimmer for training purpose. The conceptual idea is presented by describing the differential equation of the swimmer and the protocol for a factible estimation of the instantaneous power. The variables that are to be measured and estimated are identified and, consequently, the sensor and actuator systems can be selected. The high-level and detailed designs of the prototype are presented together with the protocol that is carried out in order to validate the sensor and actuation systems. The device is able to monitor the variables of interest of the swimmer together with the propulsive force and instant power. Finally, some experiments are carried out providing the results of several participants swimming in crawl, backstroke, butterfly, and breaststroke styles in the presence of different opposition force. The preliminary results show that SwimOne is valid for measuring instantaneous force and power with different loads in swimming.

This paper presents Gateway Configuration as a new concept for fast operation of a Scara parallel robot with low energy consumption. The mechanism and its kinematic problem are presented together with dynamics model. The control scheme presented consist on a conventional PID and a pre-feedforward term. For a specific trajectory we have compared the results of a conventional configuration and two gateway ones. The simulated results demonstrate that Gateway Configurations provide a high-quality end-effector position tracking with a very low energy consumption. Although results are presented for a particular trajectory, in the case of a Scara parallel robot multiple trajectories can be found in terms of Jacobian matrix and elbows mechanism distance. The results presented here allow to design an ultrafast manipulator for pick and place operations.

Assessing and keeping control of the mechanical properties of sport surfaces is a relevant task in sports since it enables athletes to train and compete safely and under equal conditions. Currently, different tests are used for assessing athlete- and ball-surface interactions in artificial turf pitches. In order to make these evaluations more agile and accessible for every facility, it is important to develop new apparatus that enable to perform the tests in an easier and quicker way. The existing equipment for determining the vertical ball behavior requires a complex and non-easily transportable device in which the ball must be fixed to the upper part of the frame in a very precise position by means of a magnet. The rebound height is determined by capturing the acoustic signal produced when the ball bounces on the turf. When extended tests are conducted, the time required to evaluate a single field is too high due to the non-valid trials. This work proposes a novel methodology which allows to notoriously decrease the time of testing fields maintaining the repeatability and accuracy of the test method together with a compact device for improving its mobility and transport. Simulations and experiments demonstrates the repeatability and accuracy of the results obtained by the proposed device, which decreases the non-valid trials and notoriously reduces the time for field evaluation. Sin financiación 3.576 JCR (2020) Q1, 14/64 Instruments & Instrumentation 0.636 SJR (2020) Q2, 46/121 Analytical Chemistry No data IDR 2019 UEM