Regular inspection of nuclear power plant components is important to guarantee safe operations. However, current practice is time consuming, tedious, and subjective, which involves human technicians ...reviewing the inspection videos and identifying cracks on reactors. A few vision-based crack detection approaches have been developed for metallic surfaces, and they typically perform poorly when used for analyzing nuclear inspection videos. Detecting these cracks is a challenging task since they are tiny, and noisy patterns exist on the components' surfaces. This study proposes a deep learning framework, based on a convolutional neural network (CNN) and a Naïve Bayes data fusion scheme, called NB-CNN, to analyze individual video frames for crack detection while a novel data fusion scheme is proposed to aggregate the information extracted from each video frame to enhance the overall performance and robustness of the system. To this end, a CNN is proposed to detect crack patches in each video frame, while the proposed data fusion scheme maintains the spatiotemporal coherence of cracks in videos, and the Naïve Bayes decision making discards false positives effectively. The proposed framework achieves a 98.3% hit rate against 0.1 false positives per frame that is significantly higher than state-of-the-art approaches as presented in this paper.
United States space policy has largely reflected the outlook of a major power. The key distinguishing feature of such a state is their willingness to proactively reshape and engage with international ...regimes and organizations. They do this to protect their strategic goals and national interest. US space policy has historically been shaped by geopolitical tensions and rivalries. Its space policy is an extension of the military doctrines and strategies that it subsequently developed. The article examines different periods since the start of the space race. These periods reflect how US space policy has adapted to meet new challenges.
Except for the Eisenhower administration's threat of nuclear retaliation to even local non-nuclear and limited aggression, the Trump administration's Nuclear Posture Review (NPR) is the most open ...description of US capabilities and strategies for employing nuclear weapons in a wide range of contingencies. Blurring the distinction between non-nuclear and nuclear war, the 2018 NPR reverses the commitment in the Obama administration's 2010 NPR to reduce the role of nuclear weapons in US grand strategy. It champions this wider role as warranted by three developments: the deterioration of the Post-Cold War relationships with Russia and China; new technologies which allow for precisely tailored nuclear attacks well short of mutual assured destruction (MAD) levels, and evidence that Moscow and Beijing are adopting such limited nuclear war capabilities and strategies; and the evident desire of other states and non-state actors hostile to the United States to acquire their own weapons of mass destruction and/or intimidation. But the 2018 NPR fails to show why modernized nuclear capabilities are better able to deter and defend against potential enemy aggression than technologicallyadvanced nonnuclear capabilities. Its presumption of controllable nuclear exchanges will reduce the calculations of risk and increase the likelihood of conflicts escalating to nuclear war.
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