Wind tunnel analysis on the influence of cantilever parapets on the wind loads on curved roofs

Different methods to reduce the high suction caused by conical vortices have been reported in the literature: vertical parapets, either solids or porous, placed at the roof edges being the most analysed configuration. Another method for alleviating the high suction peaks due to conical vortices is to round the roof edges. Very recently, the use of some non-standard parapet configurations, like cantilever parapets, has been suggested. In this paper, its efficiency to reduce suction loads on curved roofs is experimentally checked by testing the pressure distribution on the curved roof of a low-rise building model in a wind tunnel. Very high suction loads have been measured on this model, the magnitude of these high suction loads being significantly decreased when cantilever..

Influence of an upstream building on the wind-induced mean suction on the flat roof of a low-rise building

The effect of an upstream building on the suction forces on the flat roof of a low-rise building placed in the wake of the former is analyzed. The analysis has been performed by wind tunnel testing of a flat roof, low-rise building model equipped with pressure taps on the roof and different block-type buildings (only configurations where the upstream building is as high or higher than the downstream one are considered in this paper). The influence of the distance between both buildings on the wind loads on the downstream building roof is analyzed, as well as the height of the upstream one and the wind angle of incidence. Experimental results reveal that the wind load increases as the relative height of the upstream building increases, the wind load being highest for intermediate distances between buildings, when a passage between them is formed

The influence of the section shape of box-girder decks on the steady aerodynamic yawing moment of double cantilever bridges under construction

The yawing moment acting on the box-girder deck of reinforced concrete bridges constructed using the balanced cantilever method during the erection stage has been experimentally analyzed by testing different types of bridge cross-sections. Experimental results show that the yawing moment coefficient decreases as the bridge decks become streamlined, and that the yawing moment coefficient reaches a maximum when the bridge deck length is nearly twice the deck width

A parametric, experimental analysis of conical vortices on curved roofs of low-rise buildings

Different methods to reduce the high suction caused by conical vortices have been reported in the literature: vertical parapets, either solid or porous, placed at the roof edges being the most analysed configuration. Another method for alleviating the high suction peaks due to conical vortices is the use of some non-standard parapet configuration like cantilever parapets. In this paper the influence of roof curvature on the conical vortex pattern appearing on a curved roof (Fig. 1) when subject to oblique winds is experimentally analysed by testing the mean pressure distribution on the curved roofs of low-rise building models in a wind tunnel. Also, the efficiency of cantilever parapets to reduce mean suction loads on curved roofs is experimentally checked. Very high suction loads have been measured on curved roofs, the magnitude of these high suction loads being significantly decreased when cantilever parapets are used. Thus, the suitability of these parapets to reduce wind pressure loads on curved roofs is demonstrated

Fatty acid and retinol-binding protein: Unusual protein conformational and cavity changes dictated by ligand fluctuations

Lipid-binding proteins (LBPs) are soluble proteins responsible for the uptake, transport, and storage of a large variety of hydrophobic lipophilic molecules including fatty acids, steroids, and other lipids in the cellular environment. Among the LBPs, fatty acid binding proteins (FABPs) present preferential binding affinities for long-chain fatty acids. While most of FABPs in vertebrates and invertebrates present similar β-barrel structures with ligands accommodated in their central cavity, parasitic nematode worms exhibit additional unusual α-helix rich fatty acid- and retinol-binding proteins (FAR). Herein, we report the comparison of extended molecular dynamics (MD) simulations performed on the ligand-free and palmitic acid-bond states of the Necator americanus FAR-1 (Na-FAR-1) with respect to other classical β-barrel FABPs. Principal component analysis (PCA) has been used to identify the different conformations adopted by each system during MD simulations. The α-helix fold encompasses a complex internal ligand-binding cavity with a remarkable conformational plasticity that allows reversible switching between distinct states in the holo-Na-FAR-1. The cavity can change up to one-third of its size affected by conformational changes of the protein-ligand complex. Besides, the ligand inside the cavity is not fixed but experiences large conformational changes between bent and stretched conformations. These changes in the ligand conformation follow changes in the cavity size dictated by the transient protein conformation. On the contrary, protein-ligand complex in β-barrel FABPs fluctuates around a unique conformation. The significantly more flexible holo-Na-FAR-1 ligand-cavity explains its larger ligand multiplicity respect to β-barrel FABPs.Fil: Barletta Roldan, Patricio German. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Franchini, Gisela Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Córsico, Betina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Fernández Alberti, Sebastián. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Sail optimization for upwind sailing: application in a Tornado, the Olympic class catamaran.

A study of a boat’s motion is carried out in order to analyze the aerodynamic properties of the optimal sail for obtaining the maximum velocity when sailing to windward. The mechanics study shows the optimal CL and CD for a given sail and how the shape of the aerodynamic polar of the sail should be. A parametrical analysis of the aerodynamics of a sail is then carried out varying the maximum camber, position of the maximum camber in the chord direction and position of the maximum camber in the mast direction. The parametric analysis is done numerically with a vortex lattice method (VLM) and experimentally in a wind tunnel. The results show that the influence of the relevant parameters studied can be reduced to the variation of two parameters, A and B, defining the polar of the sail, CD = B + A2CL 2; and the influence of parameters A and B on the maximum VMG obtainable are calculated

Lift devices in the flight of Archaeopteryx

Archaeopteryx has played a central role in the debates on the origins of avian (and dinosaurian) flight, even though as a flier it probably represents a relatively late stage in the beginnings of fl ight. We report on aerodynamic tests using a life-sized model of Archaeopteryx performing in a low turbulence wind tunnel. Our results indicate that tail deflection significantly decreased take-off velocity and power consumption, and that the first manual digit could have functioned as the structural precursor of the alula. Such results demonstrate that Archaeopteryx had already evolved high-lift devices, which are functional analogues of those present in today's birds

An example of Space Engineering Education in Spain: a master in space based on Project-Based Learning (PBL)

This work describes the successful education experience for five years of space engineering education at the Universidad Politécnica de Madrid (UPM), Madrid, Spain. The MSc. in Space Systems (MUSE, Máster Universitario en Sistemas Espaciales) is a 2-year and 120-ECTS (European Credit Transfer and Accumulation System) master program organized by the Microgravity Institute ‘Ignacio Da Riva’ (IDR/UPM), a research institute of UPM with extensive experience in the space sector. The teaching methodology is oriented to Project Based Learning (PBL), taking advantage of the IDR/UPM Institute experience. The main purposes are to share the IDR/UPM knowledge with the students and promote their collaboration with several space scientific institutions, both national and international. In the present work, the most relevant characteristics of this master program are described, highlighting the importance of the student’s participation in actual missions. In addition, to offer practical cases in all aspects of satellite development, the IDR/UPM decided to create its own satellite development program, the UPMSats. The latest, the UPMSat-2, is an educational, scientific, and in-orbit technological demonstration microsatellite (50 kg-class) that was launched in September 2020 on-board a Vega launcher (VV-16 flight). MUSE students have participated in all phases of the mission, from design to integration, calibration, and testing, and (at present) in-orbit operation. The construction of a microsatellite, although it exceeds in time the academic duration of the master, has proven to be a very interesting and versatile tool for PBL education, since it provides practical cases at all levels of development. Furthermore, the continuity of the project encourages graduated students to continue their education with a Ph.D. and the collaboration of master and doctoral students. These reasons have made MUSE one of the most successful academic programs in space systems engineering in Spain, with high employment rates in the most prestigious space engineering institution

The UPMSat-2 Satellite: an academic project within aerospace engineering education

Today, project-based learning is a well-known methodology in engineering education. In the IDR/UPM Institute of Universidad Politécnica de Madrid (UPM), different lines of research have been developed to involve students into projects related to aerodynamics (both theoretical and experimental), fluid dynamics on low gravity, and space science (heat transfer).Although these lines of research were initially related to the Ph.D. programs integrated within the academic plan of the university, the increasing interest among the bachelor and master students on research and projects linked to the most advanced engineering techniques, prompted the IDR/UPM academic staff to offer some specific projects to these students as their final degree thesis. In the present work, the UPMSat-2 satellite project is analyzed as an academic tool to involve different groups of students into a big project,encouraging them not only to develop specific skills in relation to a single subsystem of the satellite, but also to harmonize their work with the results from other groups of students working on other different subsystems.The different groups of students were directed by the professors of the IDR/UPM Institute. These students being mainly from two different degrees at UPM: Bachelor’s Degree in Aerospace Engineering and Master’s Degree in Space Systems (MUSE). The main difference between these two groups being the amount of work carried out to fulfill the degree requirements. For the Bachelor’s Degree in Aerospace Engineering, a 300-hour average project is required, whereas for the Master’s Degree in Space Systems this limit increases to 450 hours. Taking into account the aforementioned figures, the importance of having motivated students is crucial. In this sense, a project like the UPMSat-2 has revealed itself as a formidable way to gather students and professors around a common engineering task. It should be pointed out that this kind of satellite, a 50-kg spacecraft, allows a more complex engineering management when compared to the cubesats (that is, engineering operations such as testing, integration or harnessing are closer to the ones related to commercial or military aircraft). Besides, as the UPMSat-2 is used as a platform to qualify space technologies for engineering enterprises (Iberespacio, Bartington, SSVB, Tecnobit, Arquimea…), students are in contact with commercial enterprises from the space sector, this fact being also important in order to increase their motivation. In the present work the educational benefits of the UPMSat-2 program in relation to the Master’s Degree in Space Systems (MUSE) are thoroughly described, some examples of the projects carried out by the students being summarized. satellite design, space technology, project-based learning, active learning

UPMSat-2 Micro-Satellite: In-orbit Technological Demonstration for Education and Science

The UPMSat-2 micro-satellite was launched on September the 3rd 2020 at 01:51:10 UTC from Kourou spaceport in French Guyana. The VV16 Vega Flight has been the first low Earth orbit rideshare commercial flight with a total of 53 satellites (7 of them micro-satellites) to be released by the launch vehicle, arranged in the modular SSMS (Small Spacecraft Mission Service) dispenser. UPMSat-2 is an educational, scientific and in-orbit technological demonstration microsatellite project led by the IDR/UPM research institute from Universidad Politécnica de Madrid (UPM), Spain. This mission can be considered as a logical extension of the IDR/UPM Institute activities focused on designing small satellites to be used as educational platforms of first level. Thereby, UPMSat-2 (as well as its precursor, the UPMSat-1) has the main objective to give students the competences for designing, analyzing, manufacturing, integrating, testing and operating the platform. UPMSat-2 also includes a set of scientific payloads and equipment to be tested in space, provided by research institutions and private companies. The UPMSat-2 is a 50 kg-class microsatellite developed for a 2-year LEO mission with a geometrical envelope of 0.5 x 0.5 x 0.6 m. Since launch, the satellite is orbiting the Earth in a sun-synchronous orbit of 500 km of altitude, passing over the IDR/UPM ground station four times a day. The satellite operation is being carried out by students and professors of the Master in Space Systems (MUSE), an official Master’s program of UPM organized by IDR/UPM. This work describes the most relevant characteristics of UPMSat-2, its payloads, technological contributions, and the main activities performed up to the launch, including participation in the launch campaign in French Guyana. The lessons learned during the mission are also summarized. Finally, the importance and benefits of incorporating actual space systems design and development within academic programs is also emphasized, as it improves these programs with constant and direct feedback