Yielding and fracture in tungsten and tungsten-rhenium alloys

Mechanical properties of tungsten and tungsten rhenium alloy

Lower-cost tungsten-rhenium alloys

Tungsten-rhenium alloys with a substantially more dilute rhenium content have ductilities and other mechanical properties which compare favorably with the tungsten-rhenium alloys having much higher concentrations of the costly rhenium

High-strength tungsten alloy with improved ductility

Alloy combines superior strength at elevated temperatures with improved ductility at lower temperatures relative to unalloyed tungsten. Composed of tungsten, rhenium, hafnium, and carbon, the alloy is prepared by consumable electrode vacuum arc-melting and can be fabricated into rod, plate, and sheet

Development of a prototype plastic space erectable satellite Quarterly report, Jun. - Aug. 1966

Copper plated high-density polyethylene film evaluation for space erectable satellite desig

ZyON: Enabling Spike Sorting on APSoC-Based Signal Processors for High-Density Microelectrode Arrays

Multi-Electrode Arrays and High-Density Multi-Electrode Arrays of sensors are a key instrument in neuroscience research. Such devices are evolving to provide ever-increasing temporal and spatial resolution, paving the way to unprecedented results when it comes to understanding the behaviour of neuronal networks and interacting with them. However, in some experimental cases, in-place low-latency processing of the sensor data acquired by the arrays is required. This poses the need for high-performance embedded computing platforms capable of processing in real-time the stream of samples produced by the acquisition front-end to extract higher-level information. Previous work has demonstrated that Field-Programmable Gate Array and All-Programmable System-On-Chip devices are suitable target technology for the implementation of real-time processors of High-Density Multi-Electrode Arrays data. However, approaches available in literature can process a limited number of channels or are designed to execute only the first steps of the neural signal processing chain. In this work, we propose an All-Programmable System-On-Chip based implementation capable of sorting neural spikes acquired by the sensors, to associate the shape of each spike to a specific firing neuron. Our system, implemented on a Xilinx Z7020 All-Programmable System-On-Chip is capable of executing on-line spike sorting up to 5500 acquisition channels, 43x more than state-of-the-art alternatives, supporting 18KHz acquisition frequency. We present an experimental study on a commonly used reference dataset, using on-line refinement of the sorting clusters to improve accuracy up to 82%, with only 4% degradation with respect to off-line analysis

A Bandwidth-Efficient Emulator of Biologically-Relevant Spiking Neural Networks on FPGA

Closed-loop experiments involving biological and artificial neural networks would improve the understanding of neural cells functioning principles and lead to the development of new generation neuroprosthesis. Several technological challenges require to be faced, as the development of real-time spiking neural network emulators which could bear the increasing amount of data provided by new generation High-Density Multielectrode Arrays. This work focuses on the development of a real-time spiking neural network emulator addressing fully-connected neural networks. This work presents a new way to increase the number of synapses supported by real-time neural network accelerators. The proposed solution has been implemented on the Xilinx Zynq 7020 All-Programmable SoC and can emulate fully connected spiking neural networks counting up to 3,098 Izhikevich neurons and 9.6e6 synapses in real-time, with a resolution of 0.1 ms

Dinámica de una viga con rótula elástica intermedia, carga axial y carga transversal oscilante

El análisis dinámico de vigas es un campo ampliamente estudiado por infinidad de investigadores por ejemplo cuando existen cargas transversales oscilantes sobre una viga y por otra parte ha sido también ampliamente tratado el caso de vibraciones libres de vigas cuando existe la acción de una carga axial. En este trabajo se trata el problema de vibraciones de vigas uniformes con extremos elásticamente restringidos sometidas a cargas axiales y cargas transversales que varían su intensidad armónicamente. Se presenta la ecuación diferencial y el problema de contorno obtenidos mediante el uso del cálculo de variaciones aplicado al caso de una viga Euler-Bernoulli con restricciones elásticas. La solución del problema se obtiene en forma exacta mediante el método de variación de parámetros. Se presentan resultados de vibraciones forzadas de la viga cuando se encuentra solicitada con una carga transversal variable en el tiempo y a su vez se encuentra solicitada con una carga axial. Se incluyen resultados de la viga analizando el efecto de la combinación de ambas cargas descritas.Publicado en: Mecánica Computacional vol. XXXV, no. 39Facultad de Ingenierí