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Switched-capacitor-convertors based on fractal design for output power management of triboelectric nanogenerator
2021/11/26-22:39:57

"Owing to the advantages of integration and being magnet-free and light-weight, the switched-capacitor-convertor plays an increasing role compared to traditional transformer in some specific power supply systems. However, the high output impedance and switching loss largely reduces its power efficiency, due to imperfect topology and transistors. Herein, we propose a fractal-design based switched-capacitor-convertors with characteristics including high conversion efficiency, minimum output impedance, and electrostatic voltage applicability. As a double-function output power management system for triboelectric nanogenerators, it delivers over 67 times charge boosting and 954 W m−2 power density in pulse mode, and achieves over 94% total energy transfer efficiency in constant mode. The establishment of the fractal-design switched-capacitor-convertors provides significant guidance for the development of power management toward multi-functional output for numerous applications. The successful demonstration in triboelectric nanogenerators also declares its great potential in electric vehicles, DC micro-grids etc."


Fused Filament Fabrication 3D Printing with Polymer-Derived Ceramics
2021/11/25-08:03:18

"Great advances have been made in various 3D printing methods for ceramics. Fabrication of Si-based ceramics using polymer-derived ceramics (PDCs) is gaining popularity. Using this route, preceramic polymers can be shaped in the polymer state and then pyrolyzed to produce different types of ceramics. Cellular ceramics can be manufactured using this technique. Herein, the novel fabrication of cellular ceramics with a two-step process using PDCs is reported. First cellular structures are 3D printed with fused filament fabrication (FFF) using thermoplastic polyurethane and impregnated with preceramic polymer polysilazane. Second, pyrolysis of the impregnated structure produces a self-similar ceramic cellular structure. The impact of 1) catalysts, 2) curing environment, and 3) pyrolysis sequence optimization to form cellular ceramics with fully dense SiOC(N) struts are systemically evaluated. The resultant custom ceramic components can tolerate operating temperatures of 1500 °C and can be manufactured for less than 5% of the cost of competing methods. The ceramic material is shown to be biocompatible and promotes fast cell adhesion. Finally, early-stage cell activation on the SiOC(N) structure is shown to be tunable by adjusting the porosity with this 3D printing to mimic the bone tissue geometry for bone regeneration."


Haskins pattern playback machine
2021/11/20-11:09:28

"The Pattern Playback was not a musical instrument as such but an early hardware device designed to synthesise and analyse speech, designed and built by Dr. Franklin S. Cooper and his colleagues, including John M. Borst and Caryl Haskins, at Haskins Laboratories in the late 1940s and completed in 1950.

The device converted a picture or ‘spectrogram’ of a sound back in to sound. The ‘Pattern Playback’ machine functioned in a very similar way to the Russian ANS Synthesiser using a photo-electrical system; a mercury arc-light was projected through a rotating glass disc printed with fifty harmonics of a fundamental frequency as a way of generating a range of tones. The light is then projected through an acetate ‘black and transparent’ spectrogram image that lets through the portions of light that carry frequencies corresponding to the spectrogram. The resulting ‘filtered’ light hits a photo-voltaic cell which generated the final audible sound."


Analog Speech Synthesis
2021/11/19-21:02:37

"This kit was the only one I had as a kid back in the mid 1960's. The original kit disappeared from my possession some decades ago but I fondly remember building and playing with it for years. A member of the ATCA club wrote me that he once had four or five of these kits and ganged them together to produce more complex speech sounds by sequentially generating a single, but different, sound from each kit."


Fabrication of freeform optical components by fluidic shaping
2021/11/19-08:38:25

"Freeform optical components enable advanced manipulation of light that is not possible with traditional optical systems. However, their fabrication relies on machining processes that are complex, time-consuming, and require significant infrastructure. Here we present the ability to shape liquid volumes and solidify them into desired freeform components, enabling rapid prototyping of freeform components with high surface quality. The method is based on controlling the minimum energy state of the interface between a curable optical liquid and an immersion liquid, by dictating a geometrical boundary constraint. We provide an analytical solution for the resulting topography given a predefined boundary and demonstrate the fabrication of freeform components with sub-nanometer surface roughness within minutes. Such a fabrication capability, that allows for rapid prototyping of high-quality components, has the potential to answer an unmet need in the optical design industry—allowing researchers and engineers to rapidly test freeform design concepts. It can be further envisioned to be expanded to an industrial scale, allowing for mold-less fabrication of freeform optics."


Flexure-based Delta robot
2021/11/09-15:20:57

"Mesoscale electromechanical systems find applications in fields such as medical instrumentation, soft robotics, microscopy, flexible electronics and imagining. This paper implements the printed circuit MEMS (PC-MEMS) process for the fabrication of a ‘pop-up’ flexure-based mesoscale system that exploits the simplicity of 2-D manufacturing techniques such as sheet-metal operations and laser cutting to realize a 3-D mechanism. The fabrication of a laminated Delta robot with prismatic actuation is presented to exemplify this process. A working device with actuation and functional components such as linear guides, stepper motors and limit switches is designed and fully realized. Because the mechanism is popped out of the plane to achieve its 3D shape, we present a stiffness analysis to arrive at the out-of-plane (or ‘pop-out’) angles that the planar system must accommodate so that constraints/limits on actuator torque/force can be can satisfied while producing an operational system. The simplicity of the processes makes it a candidate for the use in the emerging open-source hardware technologies for fabricating low-cost, complex, electromechanical systems."

PDF: https://sci-hub.st/https://doi.org/10.1016/j.jmapro.2016.06.016


The selfdrawing painting
2021/10/31-14:26:19

"Never get bored by your current painting! any time, any place and any color as you wish. you can let it paint whatever you want! This machine had loads, loads of prototypes. Mine is controlled by an arduino UNO with CNC shield and GRBL controller, but you can use anything that you want that reads G-codes of NC-files."


Open source all-iron battery
2021/10/30-19:49:28

"The price of renewable energy is dropping rapidly. Energy storage will be needed to take full advantage of abundant but intermittent energy sources. Even with economies of scale, the price is prohibitively high for a lithium-ion battery pack capable of storing tens of kilowatts of energy for many consumers. A more abundant and less expensive material is necessary. All-iron chemistry presents a transformative opportunity for stationary energy storage: it is simple, cheap, abundant, and safe. All-iron batteries can store energy by reducing iron (II) to metallic iron at the anode and oxidizing iron (II) to iron (III) at the cathode. The total cell is highly stable, efficient, non-toxic, and safe. The total cost of materials is $0.1 per watt-hour of capacity at wholesale prices. This battery may be a useful component of open source hardware projects that require a safe and ecologically friendly battery. This is also one of the few battery chemistries that can be built safely in a DIY setting."


Tertiarm - 3d Printed Robot Arm
2021/10/27-10:55:07

This is a first version of a low cost 3d printed robot arm. It is based on Ikea Tertial lamp.


Portrait drawing by Paul the robot
2021/10/24-15:16:58

"We describe Paul, a robotic installation that produces observational face drawings of people. Paul is a naive drawer: it does not have highlevel knowledge of the structures constitutive of the human face (such as the mouth, nose, eyes) nor the capability of learning expertise based on experience as a human would. However, Paul is able to draw using the equivalent of an artist's stylistic signature based on a number of processes mimicking drawing skills and technique, which together form a drawing cycle. Furthermore, we present here our first efforts in implementing two different versions of visual feedback to permit the robot to iteratively augment and improve a drawing which initially is built from a process of salient lines recovery. The first form of visual feedback we study we refer to as computational as it involves a purely internal (memory-based) representation of regions to render via shading by the robot. The second version we call physical as it involves the use of a camera as an ‘eye’ taking new snapshots of the artefact in progress. This is then analysed to take decisions on where and how to render shading next. A main point we emphasise in this work is the issue of embodiment of graphical systems, in our case in a robotic platform. We present our arguments in favour of such a position for the graphics community to reflect upon. Finally, we emphasise that the drawings produced by Paul have been considered of interest by fine art professionals in recent international art fairs and exhibitions, as well as by the public at large. One drawing is now in the Victoria and Albert museum collection. We identify a number of factors that may account for such perceived qualities of the produced drawings."


Criado/Created: 2018

Última actualização/Last updated: 26-11-2021 [22:40]


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(c) Tiago Charters de Azevedo