Experimental Investigation on Resistance Reduction by Means of Air-Bubbling Technique

Author(s):  
Enrico Ravina ◽  
Sofia Guidomei

The paper refers on a research activity, focused at DREAMS Lab of the University of Genoa (Italy) and still under development, oriented to experimental application of air-bubbling techniques on flat plates and hull models. In this study the reduction in the frictional resistance by air bubbling generated by customized pneumatic circuits is tested, both on the lower surfaces of flat plates characterized of different geometries of holes and on a hull model tested in towing tank. The effective shape of air bubbles is observed, and changes in the local frictional drag are measured, using flexible and low cost thin sensors at different levels of flow rate and pressure of injected air. In towing tank tests the experiments compare hull without and with holes on the bottom, modifying the characteristics of speed, pressure, flow rate and areas interested to the air injection. Systematic tests campaign has been developed, using also actuation pneumatic workbenches expressly designed for the experiments.

2015 ◽  
Vol 12 (2) ◽  
pp. 95-102
Author(s):  
Y. Yanuar ◽  
G. Gunawan ◽  
M. A. Talahatu ◽  
R. T. Indrawati ◽  
A. Jamaluddin

Resistance reduction in ship becomes an important issue to be investigated. Energy consumption and its efficiency are related toward drag reduction. Drag reduction in fluid flow can be obtained by providing polymer additives, coating, surfactants, fiber and special roughness on the surface hull. Fish skin surface coated with biopolymers viscous fluid (slime) is one method in frictional resistance reduction. The aim of this is to understanding the effect of drag reduction using eel slime biopolymer in unsymmetrical trimaran ship model. The Investigation was conducted using towing tank test with variation of velocity. The dimension of trimaran model are L = 2 m, B = 0.20 m and T = 0.065 m. The ship model resistance was precisely measured by a load cell transducer. The comparison of resistance on trimaran ship model coated and uncoated by eel slime are shown on the graph as a function of the total drag coefficient and Froude number. It is discovered the trimaran ship model by eel slime has higher drag reduction compared to trimaran with no eel slime at similar displacement. The result shows the drag reduction about 11 % at Fr 0.35.


Author(s):  
H. O. Colijn

Many labs today wish to transfer data between their EDS systems and their existing PCs and minicomputers. Our lab has implemented SpectraPlot, a low- cost PC-based system to allow offline examination and plotting of spectra. We adopted this system in order to make more efficient use of our microscopes and EDS consoles, to provide hardcopy output for an older EDS system, and to allow students to access their data after leaving the university.As shown in Fig. 1, we have three EDS systems (one of which is located in another building) which can store data on 8 inch RT-11 floppy disks. We transfer data from these systems to a DEC MINC computer using “SneakerNet”, which consists of putting on a pair of sneakers and running down the hall. We then use the Hermit file transfer program to download the data files with error checking from the MINC to the PC.


Author(s):  
Jorge Daher Nader ◽  
Amelia Patricia Panunzio ◽  
Marlene Hernández Navarro

Research is considered a function aimed at obtaining new knowledge and its application for the solution to problems or questions of a scientific nature, The universities framed in the fulfillment of their social function have a complex task given by training a competent professional who assumes research as part of their training and who learns to ask questions that they are able to solve through scientific research.  Scientific research is an indicator of the quality of processes in the university environment, so it must be increased by virtue of the results of the work carried out by research teachers and students the objective of this work is to know the perception of the teachers of the Faculty of Medical Sciences of the University of Guayaquil about the scientific activity. Objective: to know the perception of the teachers of the Faculty of Medical Sciences of the University of Guayaquil about the scientific activity. Methods: theoretical and empirical level were used, a questionnaire with closed questions aimed at knowing the opinions on the research activity in this institution was applied. Result: that of the sample analyzed 309 (39.3%) said they agreed with the training for the writing of scientific articles. 38.6% said they agree with the training on research projects. Conclusion: that teacher’s research should be enhanced to ensure the formation and development of research skills in students.


Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 526
Author(s):  
James Ditai ◽  
Aisling Barry ◽  
Kathy Burgoine ◽  
Anthony K. Mbonye ◽  
Julius N. Wandabwa ◽  
...  

The initial bedside care of premature babies with an intact cord has been shown to reduce mortality; there is evidence that resuscitation of term babies with an intact cord may also improve outcomes. This process has been facilitated by the development of bedside resuscitation surfaces. These new devices are unaffordable, however, in most of sub-Saharan Africa, where 42% of the world’s 2.4 million annual newborn deaths occur. This paper describes the rationale and design of BabySaver, an innovative low-cost mobile resuscitation unit, which was developed iteratively over five years in a collaboration between the Sanyu Africa Research Institute (SAfRI) in Uganda and the University of Liverpool in the UK. The final BabySaver design comprises two compartments; a tray to provide a firm resuscitation surface, and a base to store resuscitation equipment. The design was formed while considering contextual factors, using the views of individual women from the community served by the local hospitals, medical staff, and skilled birth attendants in both Uganda and the UK.


Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 432
Author(s):  
Guenther Retscher ◽  
Alexander Leb

A guidance and information service for a University library based on Wi-Fi signals using fingerprinting as chosen localization method is under development at TU Wien. After a thorough survey of suitable location technologies for the application it was decided to employ mainly Wi-Fi for localization. For that purpose, the availability, performance, and usability of Wi-Fi in selected areas of the library are analyzed in a first step. These tasks include the measurement of Wi-Fi received signal strengths (RSS) of the visible access points (APs) in different areas. The measurements were carried out in different modes, such as static, kinematic and in stop-and-go mode, with six different smartphones. A dependence on the positioning and tracking modes is seen in the tests. Kinematic measurements pose much greater challenges and depend significantly on the duration of a single Wi-Fi scan. For the smartphones, the scan durations differed in the range of 2.4 to 4.1 s resulting in different accuracies for kinematic positioning, as fewer measurements along the trajectories are available for a device with longer scan duration. The investigations indicated also that the achievable localization performance is only on the few meter level due to the small number of APs of the University own Wi-Fi network deployed in the library. A promising solution for performance improvement is the foreseen usage of low-cost Raspberry Pi units serving as Wi-Fi transmitter and receiver.


Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 646
Author(s):  
Victor Gomes Lauriano Souza ◽  
Marta M. Alves ◽  
Catarina F. Santos ◽  
Isabel A. C. Ribeiro ◽  
Carolina Rodrigues ◽  
...  

This work aimed to produce bionanocomposites of chitosan incorporated with zinc oxide nanoparticles (ZnO NPs) synthesized using food industry by-products and to characterize them. Such nanoparticles are highlighted due to their low cost, antimicrobial activity, accessibility, and sustainability synthesis. Four different levels of ZnO NPs (0, 0.5, 1.0, and 2.0% w/w of chitosan) were tested, and the bionanocomposites were characterized in terms of their hydrophobicity, mechanical, optical, and barrier properties. Overall, the incorporation of ZnO NPs changed the composites from brittle to ductile, with enhanced elongation at break and reduced Young Modulus and tensile strength. Thus, ZnO NPs acted as plasticizer, turning the films more flexible, due to the presence of organic compounds on the NPs. This also favored permeability of oxygen and of water vapor, but the good barrier properties were maintained. Optical properties did not change statistically with the ZnO NPs incorporation. Thus, the characterization presented in this paper may contribute to support a decision on the choice of the material’s final application.


Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6774
Author(s):  
Francisco José Vivas Fernández ◽  
José Sánchez Segovia ◽  
Ismael Martel Bravo ◽  
Carlos García Ramos ◽  
Daniel Ruiz Castilla ◽  
...  

Although the cure for the SARS-CoV-2 virus (COVID-19) will come in the form of pharmaceutical solutions and/or a vaccine, one of the only ways to face it at present is to guarantee the best quality of health for patients, so that they can overcome the disease on their own. Therefore, and considering that COVID-19 generally causes damage to the respiratory system (in the form of lung infection), it is essential to ensure the best pulmonary ventilation for the patient. However, depending on the severity of the disease and the health condition of the patient, the situation can become critical when the patient has respiratory distress or becomes unable to breathe on his/her own. In that case, the ventilator becomes the lifeline of the patient. This device must keep patients stable until, on their own or with the help of medications, they manage to overcome the lung infection. However, with thousands or hundreds of thousands of infected patients, no country has enough ventilators. If this situation has become critical in the Global North, it has turned disastrous in developing countries, where ventilators are even more scarce. This article shows the race against time of a multidisciplinary research team at the University of Huelva, UHU, southwest of Spain, to develop an inexpensive, multifunctional, and easy-to-manufacture ventilator, which has been named ResUHUrge. The device meets all medical requirements and is developed with open-source hardware and software.


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