772 research outputs found
Enhancing Deep Neural Networks Testing by Traversing Data Manifold
We develop DEEPTRAVERSAL, a feedback-driven framework to test DNNs.
DEEPTRAVERSAL first launches an offline phase to map media data of various
forms to manifolds. Then, in its online testing phase, DEEPTRAVERSAL traverses
the prepared manifold space to maximize DNN coverage criteria and trigger
prediction errors. In our evaluation, DNNs executing various tasks (e.g.,
classification, self-driving, machine translation) and media data of different
types (image, audio, text) were used. DEEPTRAVERSAL exhibits better performance
than prior methods with respect to popular DNN coverage criteria and it can
discover a larger number and higher quality of error-triggering inputs. The
tested DNN models, after being repaired with findings of DEEPTRAVERSAL, achieve
better accurac
MDPFuzz: Testing Models Solving Markov Decision Processes
The Markov decision process (MDP) provides a mathematical framework for
modeling sequential decision-making problems, many of which are crucial to
security and safety, such as autonomous driving and robot control. The rapid
development of artificial intelligence research has created efficient methods
for solving MDPs, such as deep neural networks (DNNs), reinforcement learning
(RL), and imitation learning (IL). However, these popular models for solving
MDPs are neither thoroughly tested nor rigorously reliable.
We present MDPFuzzer, the first blackbox fuzz testing framework for models
solving MDPs. MDPFuzzer forms testing oracles by checking whether the target
model enters abnormal and dangerous states. During fuzzing, MDPFuzzer decides
which mutated state to retain by measuring if it can reduce cumulative rewards
or form a new state sequence. We design efficient techniques to quantify the
"freshness" of a state sequence using Gaussian mixture models (GMMs) and
dynamic expectation-maximization (DynEM). We also prioritize states with high
potential of revealing crashes by estimating the local sensitivity of target
models over states.
MDPFuzzer is evaluated on five state-of-the-art models for solving MDPs,
including supervised DNN, RL, IL, and multi-agent RL. Our evaluation includes
scenarios of autonomous driving, aircraft collision avoidance, and two games
that are often used to benchmark RL. During a 12-hour run, we find over 80
crash-triggering state sequences on each model. We show inspiring findings that
crash-triggering states, though look normal, induce distinct neuron activation
patterns compared with normal states. We further develop an abnormal behavior
detector to harden all the evaluated models and repair them with the findings
of MDPFuzzer to significantly enhance their robustness without sacrificing
accuracy
3D Hierarchical Co–Al Layered Double Hydroxides with Long-Term Stabilities and High Rate Performances in Supercapacitors
The effect of cage ventilation rate on the health of mice housed in Individually Ventilated Cages
The number of air changes per hour (ACH), an important index for individually ventilated cages (IVC), strongly affects the cage microenvironment and the health of laboratory animals. The objective of this study was to determine whether high or low cage ventilation adversely affects the health of mice housed in IVC systems and to identify cage ventilation rates suitable for the welfare of mice. We tested three different cage ventilation rates (40, 60, and 80 ACH) for 3 weeks in an IVC system. The temperature, relative humidity and ammonia concentrations in the cages were measured daily. The indices used to assess mouse health at specific time points throughout the study were body weight, stress hormones, T lymphocyte subsets (CD4 and CD8), immunoglobulins (IgG, IgM and IgA) and immune cells. There were no significant differences in body weight, growth hormones, immunoglobulin and T lymphocyte subsets in the IVC groups compared with the control group. The concentrations of corticosterone and epinephrine on day 7 of cage ventilation at 80 ACH were significantly higher than those in the control group (P < 0.05). Mice housed in 80 ACH cages had the lowest immune cell counts among all groups, and the numbers of lymphocytes and neutrophils were significantly lower than those in the control group (P < 0.05). In summary, cage ventilation at 60 ACH provided an optimum cage microenvironment for mouse health and welfare
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