Ion-selective field-effect transistors (ISFETs) are widely used for chemical sensing in biomedical and environmental applications. They require calibration before deployment in the field because of individual sensor response variations and temporal drift in their readout. However, calibration can be time-consuming if a large number of ISFETs are to be deployed. This work proposes an end-to-end prediction neural network where individual sensor calibrations are not needed. We train the network to predict the ionic concentration by using a simulated dataset of responses from a physical ISFET model to varying sodium concentrations. The model includes the known non-idealities of real ISFET sensors. Our network also outputs a confidence interval for the prediction which can be useful for determining the quality of the prediction. On a dataset of real sodium ISFET recordings, our end-to-end prediction network gave a decrease of at least 42% in the prediction error of sodium concentration compared to that from ISFETs calibrated using two manual methods.

Spiking silicon cochlea sensors encode sound as an asynchronous stream of spikes from different frequency channels. The lack of labeled training datasets for spiking cochleas makes it difficult to train deep neural networks on the outputs of these sensors. This work proposes a self-supervised method called Temporal Network Grafting Algorithm (T-NGA), which grafts a recurrent network pretrained on spectrogram features so that the network works with the cochlea event features. T-NGA training requires only temporally aligned audio spectrograms and event features. Our experiments show that the accuracy of the grafted network was similar to the accuracy of a supervised network trained from scratch on a speech recognition task using events from a software spiking cochlea model. Despite the circuit non-idealities of the spiking silicon cochlea, the grafted network accuracy on the silicon cochlea spike recordings was only about 5% lower than the supervised network accuracy using the N-TIDIGITS18 dataset. T-NGA can train networks to process spiking audio sensor events in the absence of large labeled spike datasets.

Event cameras report local changes of brightness through an asynchronous stream of output events. Events are spatially sparse at pixel locations with little brightness variation. We propose using a visual transformer (ViT) architecture to leverage its ability to process a variable-length input. The input to the ViT consists of events that are accumulated into time bins and spatially separated into non-overlapping sub-regions called patches. Patches are selected when the number of nonzero pixel locations within a sub-region is above a threshold. We show that by fine-tuning a ViT model on these selected active patches, we can reduce the average number of patches fed into the backbone during the inference by at least 50% with only a minor drop (0.34%) of the classification accuracy on the N-Caltech101 dataset. This reduction translates into a decrease of 51% in Multiply-Accumulate (MAC) operations and an increase of 46% in the inference speed using a server CPU.

Deep Neural Networks, particularly Convolutional Neural Networks (ConvNets), have achieved incredible success in many vision tasks, but they usually require millions of parameters for good accuracy performance. With increasing applications that use ConvNets, updating hundreds of networks for multiple tasks on an embedded device can be costly in terms of memory, bandwidth, and energy. Approaches to reduce this cost include model compression and parameter-efficient models that adapt a subset of network layers for each new task. This work proposes a novel parameter-efficient kernel modulation (KM) method that adapts all parameters of a base network instead of a subset of layers. KM uses lightweight task-specialized kernel modulators that require only an additional 1.4% of the base network parameters. With multiple tasks, only the task-specialized KM weights are communicated and stored on the end-user device. We applied this method in training ConvNets for Transfer Learning and Meta-Learning scenarios. Our results show that KM delivers up to 9% higher accuracy compared to other parameter-efficient methods on the Transfer Learning benchmark.

We explore the suitability of self-attention models for character-level neural machine translation.We test the standard transformer model, as well as a novel variant in which the encoder block combines information from nearby characters using convolutions.We perform extensive experiments on WMT and UN datasets, testing both bilingual and multilingual translation to English using up to three input languages (French, Spanish, and Chinese).Our transformer variant consistently outperforms the standard transformer at the character-level and converges faster while learning more robust character-level alignments. 1

Hardware accelerators for Deep Neural Networks (DNNs) that use reduced precision parameters are more energy efficient than the equivalent full precision networks. While many studies have focused on reduced precision training methods for supervised networks with the availability of large datasets, less work has been reported on incremental learning algorithms that adapt the network for new classes and the consequence of reduced precision has on these algorithms. This paper presents an empirical study of how reduced precision training methods impact the iCARL incremental learning algorithm. The incremental network accuracies on the CIFAR-100 image dataset show that weights can be quantized to 1 bit (2.39% drop in accuracy) but when activations are quantized to 1 bit, the accuracy drops much more (12.75%). Quantizing gradients from 32 to 8 bits only affects the accuracies of the trained network by less than 1%. These results are encouraging for hardware accelerators that support incremental learning algorithms.