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Hardware accelerators are essential to the accommodation of ever-increasing Deep Neural Network (DNN) workloads on the resource-constrained embedded devices. While accelerators facilitate fast and energy-efficient DNN operations, their accuracy is threatened by faults in their on-chip and off-chip memories, where millions of DNN weights are held. The use of emerging Non-Volatile Memories (NVM) further exposes DNN accelerators to a non-negligible rate of permanent defects due to immature fabrication, limited endurance, and aging. To tolerate defects in NVM-based DNN accelerators, previous work either requires extra redundancy in hardware or performs defect-aware retraining, imposing significant overhead. In comparison, this paper proposes a set of algorithms that exploit the flexibility in setting the fault-free bits in weight memory to effectively approximate weight values, so as to mitigate defect-induced accuracy drop. These algorithms can be applied as a one-step solution when loading the weights to embedded devices. They only require trivial hardware support and impose negligible run-time overhead. Experiments on popular DNN models show that the proposed techniques successfully boost inference accuracy even in the face of elevated defect rates in the weight memory. 

ReRAM-based neural network accelerator is a promising solution to handle the memory- and computation-intensive deep learning workloads. However, it suffers from unique device errors. These errors can accumulate to massive levels during the run time and cause significant accuracy drop. It is crucial to obtain its fault status in real-time before any proper repair mechanism can be applied. However, calibrating such statistical information is non-trivial because of the need of a large number of test patterns, long test time, and high test coverage considering that complex errors may appear in million-to-billion weight parameters. In this paper, we leverage the concept of corner data that can significantly confuse the decision making of neural network model, as well as the training algorithm, to generate only a small set of test patterns that is tuned to be sensitive to different levels of error accumulation and accuracy loss. Experimental results show that our method can quickly and correctly report the fault status of a running accelerator, outperforming existing solutions in both detection efficiency and cost. 

ReRAM-based neural network accelerator is a promising solution to handle the memory- and computation-intensive deep learning workloads. However, it suffers from unique device errors. These errors can accumulate to massive levels during the run time and cause significant accuracy drop. It is crucial to obtain its fault status in real-time before any proper repair mechanism can be applied. However, calibrating such statistical information is non-trivial because of the need of a large number of test patterns, long test time, and high test coverage considering that complex errors may appear in million-to-billion weight parameters. In this paper, we leverage the concept of corner data that can significantly confuse the decision making of neural network model, as well as the training algorithm, to generate only a small set of test patterns that is tuned to be sensitive to different levels of error accumulation and accuracy loss. Experimental results show that our method can quickly and correctly report the fault status of a running accelerator, outperforming existing solutions in both detection efficiency and cost. 

While Volatile Organic Compounds (VOC) and ammonia have a place in our daily lives, their leakage into the environment is harmful to human health. In order to prevent and detect gaseous leaks of harmful VOCs, a cyber-physical system (CPS) comprised of ordinary people or first responders is proposed. This CPS uses small, low-cost sensors coupled to smart phones or mobile devices with the necessary computation and communication capabilities. The efficacy of such a CPS hinges on its ability to address technical challenges stemming from the fact that identically produced sensors may produce different results under the same conditions due to sensor drift, noise, or resolution errors. The proposed system makes use of time-varying signals produced by sensors to detect gas leaks. Sensors sample the gas vapor level in a continuous manner and time-varying sensor data is processed using deep neural networks. One of the neural networks (NN) is an energy efficient Additive Neural Network (AddNet) which can be implemented in host devices. The second NN is the discriminator of a GAN and the third a regular convolutional NN. AddNet produces comparable VOC gas leak detection results to regular convolutional networks while reducing area requirements by two thirds.