8 documents found, page 1 of 1

Network nodes for ocean data exchange through submarine fiber optic cable repea...

As humanity progresses and globalization advances, humanized environment and associated systems increase in complexity and size. In earth systems, oceans represent an essential element of equalization and normal functioning. Ocean-atmospheric interactions are nowadays believed to be at the heart of all earth vital signs and climatic behaviours, and therefore are essential to accurate monitoring and understandin...

Family interview to enable donation of organs for transplantation: evidence-bas...

High frequency wide beam PVDF ultrasonic projector for underwater communications

This work describes the development and characterization of a wide beam and wideband ultrasonic transducer, designed as an emitter for underwater communications up to 1.5 MHz. The active element being used is composed of two layers of 110 mu m PVDF (Polyvinylidene fluoride) film, with NiCu electrodes. The transducer has a semicircular shape with a diameter of 15 cm. Pool trials show a transmitting voltage respo...

Effect of anion type in the performance of ionic liquid/poly(vinylidene fluorid...

Low voltage actuators based on poly(vinylidene fluoride)(PVDF)with 10, 25 and 40 % 1-hexyl-3-methylimidazolium chloride ([C6mim][Cl])and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][NTf2]) are prepared by solvent casting in order to evaluate the effect of anion size in the bending properties. Independently of the ionic liquid type and content, its presence leads to the crystallization ...

Electromechanical actuators based on poly(vinylidene fluoride) with [N1 1 1 2(O...

Actuators based on electroactive polymers are increasingly used in applications including microelectronic devices and artificial muscles, demanding low voltage operation and controllable switching response. This work reports on the preparation of electroactive actuators based on poly(vinylidene fluoride) (PVDF) composites with 10, 25, and 40 wt% N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulf...

Effect of the acoustic impedance in ultrasonic emitter transducers using digita...

In an underwater environment it is difficult to implement solutions for wireless communications. The existing technologies using electromagnetic waves or lasers are not very efficient due to the large attenuation in the aquatic environment. Ultrasound reveals a lower attenuation, and thus has been used in underwater long-distance communications. The much slower speed of acoustic propagation in water (about 1500...

Estatística espacial de varredura na detecção de áreas de risco para a cisticer...

p. 1200-1208; Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2014-05-06T14:33:41Z No. of bitstreams: 1 M.E. Bavia.pdf: 637074 bytes, checksum: 06a973f224db141d4116636cf965db26 (MD5); Approved for entry into archive by Alda Lima da Silva (sivalda@ufba.br) on 2014-09-11T18:34:36Z (GMT) No. of bitstreams: 1 M.E. Bavia.pdf: 637074 bytes, checksum: 06a973f224db141d4116636cf965db26 (MD5); Made available in D...

Análise das agressões em humanos por morcegos hematófagos ocorridas em três mun...

p. 1-7; Submitted by RI Repositorio (repositorio@ufba.br) on 2011-07-18T19:35:07Z No. of bitstreams: 1 669-2583-2-PB.pdf: 138585 bytes, checksum: 9379e35b23c6449e11a361ded097a1bc (MD5); Made available in DSpace on 2011-07-18T19:35:07Z (GMT). No. of bitstreams: 1 669-2583-2-PB.pdf: 138585 bytes, checksum: 9379e35b23c6449e11a361ded097a1bc (MD5) Previous issue date: 2005; Este trabalho trata do estudo descritivo d...