146 research outputs found
A practical technique for the generation of highly uniform LIPSS
AbstractLaser-induced periodic surface structures (LIPSS) can be reliably produced with ultrashort (<10ps) laser pulses given fluence near the ablation threshold. Neat, parallel, uniform structures are harder to reproduce. Electrodynamic models show a field at normal incidence interacts with the surface resulting in periodicity in intensity along the surface in the direction of the incident E-field producing ridges and toughs on the surface orthogonal to the E-field. A completely smooth surface offers nothing to perturb the eventual periodic feature formation but is very difficult to achieve: we have demonstrated that simply avoiding surface roughness components near the frequency and direction of the emergent features significantly improves uniform feature production. An appropriate unidirectional polishing process can be realised using an inexpensive spinning cloth wheel. By using a cylindrical lens we were also able to process stainless steel surfaces at 5mm2s−1 so indicating useful industrial potential
FreezeOut: Accelerate Training by Progressively Freezing Layers
The early layers of a deep neural net have the fewest parameters, but take up
the most computation. In this extended abstract, we propose to only train the
hidden layers for a set portion of the training run, freezing them out
one-by-one and excluding them from the backward pass. Through experiments on
CIFAR, we empirically demonstrate that FreezeOut yields savings of up to 20%
wall-clock time during training with 3% loss in accuracy for DenseNets, a 20%
speedup without loss of accuracy for ResNets, and no improvement for VGG
networks. Our code is publicly available at
https://github.com/ajbrock/FreezeOutComment: Extended Abstrac
Generative and Discriminative Voxel Modeling with Convolutional Neural Networks
When working with three-dimensional data, choice of representation is key. We
explore voxel-based models, and present evidence for the viability of
voxellated representations in applications including shape modeling and object
classification. Our key contributions are methods for training voxel-based
variational autoencoders, a user interface for exploring the latent space
learned by the autoencoder, and a deep convolutional neural network
architecture for object classification. We address challenges unique to
voxel-based representations, and empirically evaluate our models on the
ModelNet benchmark, where we demonstrate a 51.5% relative improvement in the
state of the art for object classification.Comment: 9 pages, 5 figures, 2 table
SMASH: One-Shot Model Architecture Search through HyperNetworks
Designing architectures for deep neural networks requires expert knowledge
and substantial computation time. We propose a technique to accelerate
architecture selection by learning an auxiliary HyperNet that generates the
weights of a main model conditioned on that model's architecture. By comparing
the relative validation performance of networks with HyperNet-generated
weights, we can effectively search over a wide range of architectures at the
cost of a single training run. To facilitate this search, we develop a flexible
mechanism based on memory read-writes that allows us to define a wide range of
network connectivity patterns, with ResNet, DenseNet, and FractalNet blocks as
special cases. We validate our method (SMASH) on CIFAR-10 and CIFAR-100,
STL-10, ModelNet10, and Imagenet32x32, achieving competitive performance with
similarly-sized hand-designed networks. Our code is available at
https://github.com/ajbrock/SMAS
Laser microsculpting for the generation of robust diffractive security markings on the surface of metals
AbstractWe report the development of a laser-based process for the direct writing (‘microsculpting’) of unique security markings (reflective phase holograms) on the surface of metals. In contrast to the common approaches used for unique marking of the metal products and components, e.g., polymer holographic stickers which are attached to metals as an adhesive tape, our process enables the generation of the security markings directly onto the metal surface and thus overcomes the problems with tampering and biocompatibility which are typical drawbacks of holographic stickers. The process uses 35ns laser pulses of wavelength 355nm to generate optically-smooth deformations on the metal surface using a localised laser melting process. Security markings (holographic structures) on 304-grade stainless steel surface are fabricated, and their resulted optical performance is tested using a He–Ne laser beam of 632.8nm wavelength
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