Study of a Hydroelastic Instability Phenomenon: Flutter of Racing Yacht Keels

2012 ◽  
Author(s):  
Rémy Balze ◽  
Hervé Devaux ◽  
Louis Jézéquel
Keyword(s):  
Critical Speed ◽  
Low Cost ◽  
Flexible Structure ◽  
Additional Energy ◽  
Fluid Medium ◽  
3 Dimensional ◽  
Instability Phenomenon ◽  
Physics Simulation ◽  
Fluid Damping ◽  
First Time

In the field of aeroelasticity, flutter is a well known instability phenomenon. Flutter is a synchronized vibration which takes place in a flexible structure moving through a fluid medium. It occurs when two regular, rhythmic motions coincide in such a way that one feeds the other, drawing additional energy from surrounding flow. A classic case of wing flutter might combine wing bending with either wing twisting. This article explores the flutter phenomenon in water. An important difference from the flutter phenomenon in air is the fact that the flexible structure is evolving in heavy fluid; this implies in particular added mass effects and important fluid damping. Flutter appeared for the first time on racing yacht keels with composite fins, so in water, in 2004: • On the IMOCA 60 feet boat POUJOULAT-ARMORLUX of Bernard STAMM during the transatlantic race ‘The Transat’: he lost his keel and capsized. • On the IMOCA 60 feet boat SILL Rolland JOURDAIN: the keel and the boat were saved. Following these problems — particularly following the loss of the keel of Bernard STAMM sailboat, accident that could have dramatic consequences for the skipper — HDS company focused on the phenomenon. Flutter has occurred only for canting keels with composite fins on IMOCA 60 feet and Volvo 70 feet racing yacht. The main questions asked are “Why are composite keels susceptible to flutter, and is it possible to predict and prevent this behaviour?”, then “Can a fair indication of the flutter critical speed of the keel be given at low cost?”. This presentation will introduce the strategy of HDS faced to the problem and the analytical and numerical methods implemented to estimate the flutter critical speed. Our model is based on a truncated modal basis for the most energetic modes which are generally, for a bulb keel, the lateral bending predominant mode and the torsion predominant mode. One of our requirements was to make a simple model in order to integrate the calculation of the flutter critical speed in the first design loops of a composite or steel keel. This model has worked well for the two cases of flutter appeared on IMOCA sailboat keels. Besides, to verify the quality of the model and to complete our analysis of flutter phenomenon on racing yacht keels, a 3 dimensional multi-physics simulation has been developed using the software ADINA.

scholarly journals UV Inscription and Pressure Induced Long-Period Gratings through 3D Printed Amplitude Masks

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1977
Author(s):  
Ricardo Oliveira ◽  
Liliana M. Sousa ◽  
Ana M. Rocha ◽  
Rogério Nogueira ◽  
Lúcia Bilro
Keyword(s):  
State Of The Art ◽  
Low Cost ◽  
Resonance Wavelength ◽  
Complex Structures ◽  
Pressing Method ◽  
Long Period ◽  
Long Period Gratings ◽  
3D Printed ◽  
Mechanical Pressing ◽  
First Time

In this work, we demonstrate for the first time the capability to inscribe long-period gratings (LPGs) with UV radiation using simple and low cost amplitude masks fabricated with a consumer grade 3D printer. The spectrum obtained for a grating with 690 µm period and 38 mm length presented good quality, showing sharp resonances (i.e., 3 dB bandwidth < 3 nm), low out-of-band loss (~0.2 dB), and dip losses up to 18 dB. Furthermore, the capability to select the resonance wavelength has been demonstrated using different amplitude mask periods. The customization of the masks makes it possible to fabricate gratings with complex structures. Additionally, the simplicity in 3D printing an amplitude mask solves the problem of the lack of amplitude masks on the market and avoids the use of high resolution motorized stages, as is the case of the point-by-point technique. Finally, the 3D printed masks were also used to induce LPGs using the mechanical pressing method. Due to the better resolution of these masks compared to ones described on the state of the art, we were able to induce gratings with higher quality, such as low out-of-band loss (0.6 dB), reduced spectral ripples, and narrow bandwidths (~3 nm).

scholarly journals The physics of galaxy evolution with SPICA observations

2019 ◽  
Vol 15 (S359) ◽  
pp. 72-77
Author(s):  
Luigi Spinoglio ◽  
Juan A. Fernández-Ontiveros ◽  
Sabrina Mordini
Keyword(s):  
Galaxy Evolution ◽  
Cosmic Time ◽  
Medium Size ◽  
3 Dimensional ◽  
Cosmic Vision ◽  
Infrared Telescope ◽  
Black Hole Accretion ◽  
Esa Cosmic Vision ◽  
Cluster Cores ◽  
First Time

AbstractThe evolution of galaxies at Cosmic Noon (1 < z < 3) passed through a dust-obscured phase, during which most stars formed and black holes in galactic nuclei started to shine, which cannot be seen in the optical and UV, but it needs rest frame mid-to-far IR spectroscopy to be unveiled. At these frequencies, dust extinction is minimal and a variety of atomic and molecular transitions, tracing most astrophysical domains, occur. The Space Infrared telescope for Cosmology and Astrophysics (SPICA), currently under evaluation for the 5th Medium Size ESA Cosmic Vision Mission, fully redesigned with its 2.5-m mirror cooled down to T < 8K will perform such observations. SPICA will provide for the first time a 3-dimensional spectroscopic view of the hidden side of star formation and black hole accretion in all environments, from voids to cluster cores over 90% of cosmic time. Here we outline what SPICA will do in galaxy evolution studies.

scholarly journals Nanoliposomal Cercodemasoide A and Its Improved Activities Against NTERA-2 Cancer Stem Cells

2020 ◽  
Vol 15 (12) ◽  
pp. 1934578X2098210
Author(s):  
Nguyen Thi Nga ◽  
Do Thi Phuong ◽  
Nguyen Thi Cuc ◽  
Trieu Ha Phuong ◽  
Pham Thi Mai Huong ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
Drug Carrier ◽  
Free Form ◽  
Cancer Therapies ◽  
3 Dimensional ◽  
Novel Target ◽  
Average Size ◽  
Biopharmaceutical Properties ◽  
First Time

Recently, saponins derived from marine sources have received much attention because of their promising bioactivities, such as anticancer, anti-angiogenesis, and anti-inflammation. In particular, a triterpene saponin from the sea cucumber Cercodemas anceps Selenka, cercodemasoide A (CAN1), showed potent cytotoxicity against various cancer cell lines. Recent evidence has indicated that cancer stem cells (CSCs) could be a novel target for efficient cancer therapies. In order to improve the biopharmaceutical properties of CAN1, the compound was loaded into nanoliposomes as an ideal drug carrier. CAN1 was successfully incorporated into nanoliposomes as small unilamellar liposome vesicles with an average size of 73.39 ± 1.57 nm, zeta potential of −0.299 ± 0.046 mV, polydispersity index of 0.336 ± 0.038, and with an encapsulation efficiency of up to 62.9%. For the first time, CAN1 and its nanoliposomal forms have been shown to have a promising cytotoxic activity against NTERA-2 CSCs, with half-maximal inhibitory concentration (IC50) =1.03 ± 0.04 and 0.41 ± 0.03 µM, respectively. The CAN1 nanoliposomes also presented significantly improved activities in suppressing the growth of NTERA-2 3-dimensional tumorspheres (IC50 = 1.71 ± 0.06 µM) in comparison with the free form ( P < .05). The anti-CSC effects of CAN1 nanoliposomes on NTERA-2 cells were due to their apoptotic induction through enhancing caspase-3 activity (more than 2-fold) and arresting the cell cycle at the S phase ( P < .05). The obtained CAN1-encapsulated nanoliposomes suggest valuable applications in CSC-targeting treatment for more efficient clinical therapy.

Experimental observation of viscoelastic fluid–structure interactions

2017 ◽  
Vol 813 ◽  
Author(s):  
Anita A. Dey ◽  
Yahya Modarres-Sadeghi ◽  
Jonathan P. Rothstein
Keyword(s):  
Flow Instability ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Flexible Structure ◽  
Fluid Inertia ◽  
Fluid Structure Interactions ◽  
Periodic Oscillations ◽  
Fluid Structure ◽  
Dependent Growth ◽  
First Time

It is well known that when a flexible or flexibly mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices. Here, we show for the first time that fluid–structure interactions can also be observed when the fluid is viscoelastic. For viscoelastic fluids, a flexible structure can become unstable in the absence of fluid inertia, at infinitesimal Reynolds numbers, due to the onset of a purely elastic flow instability. Nonlinear periodic oscillations of the flexible structure are observed and found to be coupled to the time-dependent growth and decay of viscoelastic stresses in the wake of the structure.

Printing ultrathin graphene oxide nanofiltration membranes for water purification

2017 ◽  
Vol 5 (39) ◽  
pp. 20860-20866 ◽  
Author(s):  
Mahdi Fathizadeh ◽  
Huynh Ngoc Tien ◽  
Konstantin Khivantsev ◽  
Jung-Tsai Chen ◽  
Miao Yu
Keyword(s):  
Graphene Oxide ◽  
Water Purification ◽  
Inkjet Printing ◽  
Low Cost ◽  
Nanofiltration Membranes ◽  
Highly Effective ◽  
First Time ◽  
Polymeric Supports ◽  
Effective Water

We demonstrated for the first time that inkjet printing can be a low-cost, easy, fast, and scalable method for depositing ultrathin (7.5–60 nm) uniform graphene oxide (GO) nanofiltration membranes on polymeric supports for highly effective water purification.

Antimony trifluoride incorporated SnO2 for high-efficiency planar perovskite solar cells

2021 ◽  
Author(s):  
Li Zhang ◽  
Hui Li ◽  
Jing Zhuang ◽  
Yigang Luan ◽  
Sixuan Wu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Transport ◽  
Tin Dioxide ◽  
High Efficiency ◽  
Low Cost ◽  
Perovskite Solar Cells ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Antimony Trifluoride ◽  
First Time

The low-cost material antimony trifluoride (SbF3) was doped into the commonly used tin dioxide (SnO2) for the first time, and the SbF3-doped SnO2 as an electron transport layer (ETL) was...

New Results of Using the Light Trap for Collecting Beetles (Insecta: Coleoptera) in the Urban Environment (on the Example of Saratov)

2020 ◽  
Vol 2 (2) ◽  
pp. 72-78
Author(s):  
A.S. Sazhnev ◽  
◽  
V.V. Anikin ◽  
Keyword(s):  
Invasive Species ◽  
Urban Areas ◽  
Harmonia Axyridis ◽  
Low Cost ◽  
Light Trap ◽  
Ecological Groups ◽  
Light Traps ◽  
Adventitious Species ◽  
First Time ◽  
Stegobium Paniceum

The article presents the results of research of the using light traps (luminescent lamp Actinic 6W) for collecting Coleoptera in the Saratov city. Entomological material was collected by the second author in the period from 1.06 to 2.10.2019. In 2019, 52 species of Coleoptera of 22 families from different ecological groups were recorded. A relatively high proportion of adventitious species remains in 17.3– 30.7% of the presented fauna was presented. For two years the 14 species of alien and cryptogenic Coleoptera species were observed, that is 24.5% of the adventive fauna of the Saratov Province. Among invasive species Attagenus smirnovi, Stegobium paniceum, Atomaria lewisi, Harmonia axyridis, Gnatocerus cornutus, and Orchestes steppensis were record for the first time in 2019. It to use bringing on light as one of the available and low-cost ways to identify alien and cryptogenic organisms in urban areas is recommended.

Impact of the Karnofsky Performance Status on Survival and its Dynamics during the Terminal Year of Peritoneal Dialysis Patients

2018 ◽  
Vol 38 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Ana Paula Modesto ◽  
Len Usvyat ◽  
Viviane Calice-Silva ◽  
Dandara Novakowski Spigolon ◽  
Ana Elizabeth Figueiredo ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Family Income ◽  
Independent Predictor ◽  
Karnofsky Performance Status ◽  
Low Cost ◽  
Performance Status ◽  
Multi Center Study ◽  
Complications And Mortality ◽  
First Time

Background Simple and low-cost tools to monitor the risk profile of patients on peritoneal dialysis (PD) at high risk of complications and mortality are scarce. One of the tools available to monitor the variation in vitality and dependence levels is the Karnofsky performance status (KPS). This study analyzed the average trends and variation of KPS during the 12 months before death and its independent value in predicting patients’ survival. Methods The data were compiled from the BRAZPD II multi-center study, performed in Brazil between 2004 and 2011. For the analysis of KPS dynamics, we included patients with at least 12 months of follow-up on PD and who had a fatal event during the follow-up. The following covariables were evaluated: age, gender, ethnicity, educational level, and presence of diabetes. We used the linear regression model to present the results: the log (time) before death was represented by the regression variable and KPS was the response. We also analyzed the independent impact of baseline KPS on patients’ survival. Results From the population of 9,905 patients enrolled in the BRAZPD study, 4,133 survived 12 months on PD and were included in the analysis. There was a gradual decline in the KPS scores, which accelerated in the last 2 months before death. These changes were similar irrespective of age, race, family income, gender, diabetes, PD modality, and education level. We observed 989 fatal events in this population during the observation period, and the KPS score was identified as an independent predictor for mortality in this cohort. Conclusions This study demonstrates for the first time the dynamics of KPS before death in PD patients, indicating a progressive and accelerated decline of KPS in the 12 months before patients died. In addition, KPS was an independent predictor of mortality in this population.

scholarly journals Controlled Assembly of Nanorod TiO2 Crystals via a Sintering Process: Photoanode Properties in Dye-Sensitized Solar Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Saeid Vafaei ◽  
Kazuhiro Manseki ◽  
Soki Horita ◽  
Masaki Matsui ◽  
Takashi Sugiura
Keyword(s):  
Solar Cells ◽  
Low Cost ◽  
Semiconductor Nanocrystals ◽  
Photovoltaic Performance ◽  
Dye Sensitized Solar Cells ◽  
Sintering Process ◽  
Dye Sensitized ◽  
First Time ◽  
Sensitized Solar Cells ◽  
Control Crystallization

We present for the first time a synthetic method of obtaining 1D TiO2 nanorods with sintering methods using bundle-shaped 3D rutile TiO2 particles (3D BR-TiO2) with the dimensions of around 100 nm. The purpose of this research is (i) to control crystallization of the mixture of two kinds of TiO2 semiconductor nanocrystals, that is, 3D BR-TiO2 and spherical anatase TiO2 (SA-TiO2) on FTO substrate via sintering process and (ii) to establish a new method to create photoanodes in dye-sensitized solar cells (DSSCs). In addition, we focus on the preparation of low-cost and environmentally friendly titania electrode by adopting the “water-based” nanofluids. Our results provide useful guidance on how to improve the photovoltaic performance by reshaping the numerous 3D TiO2 particles to 1D TiO2-based electrodes with sintering technique.

scholarly journals UNDERWATER PHOTOGRAMMETRY DIGITAL SURFACE MODEL (DSM) OF THE SUBMERGED SITE OF THE ANCIENT LIGHTHOUSE NEAR QAITBAY FORT IN ALEXANDRIA, EGYPT

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 1-8 ◽  
Author(s):  
M. Abdelaziz ◽  
M. Elsayed
Keyword(s):  
3D Model ◽  
Low Cost ◽  
Data Gathering ◽  
Archaeological Site ◽  
3D Models ◽  
Surface Model ◽  
Digital Surface Model ◽  
Architectural Elements ◽  
3D Photogrammetry ◽  
First Time

<p><strong>Abstract.</strong> Underwater photogrammetry in archaeology in Egypt is a completely new experience applied for the first time on the submerged archaeological site of the lighthouse of Alexandria situated on the eastern extremity of the ancient island of Pharos at the foot of Qaitbay Fort at a depth of 2 to 9 metres. In 2009/2010, the CEAlex launched a 3D photogrammetry data-gathering programme for the virtual reassembly of broken artefacts. In 2013 and the beginning of 2014, with the support of the Honor Frost Foundation, methods were developed and refined to acquire manual photographic data of the entire underwater site of Qaitbay using a DSLR camera, simple and low cost materials to obtain a digital surface model (DSM) of the submerged site of the lighthouse, and also to create 3D models of the objects themselves, such as statues, bases of statues and architectural elements. In this paper we present the methodology used for underwater data acquisition, data processing and modelling in order to generate a DSM of the submerged site of Alexandria’s ancient lighthouse. Until 2016, only about 7200&amp;thinsp;m<sup>2</sup> of the submerged site, which exceeds more than 13000&amp;thinsp;m<sup>2</sup>, was covered. One of our main objectives in this project is to georeference the site since this would allow for a very precise 3D model and for correcting the orientation of the site as regards the real-world space.</p>

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