The recent advancements in the fields of artificial intelligence (AI) and machine learning (ML) have affected several research fields, leading to improvements that could not have been possible with conventional optimization techniques. Among the sectors where AI/ML enables a plethora of opportunities, industrial manufacturing can expect significant gains from the increased process automation. At the same time, the introduction of the Industrial Internet of Things (IIoT), providing improved wireless connectivity for real-time manufacturing data collection and processing, has resulted in the culmination of the fourth industrial revolution, also known as Industry 4.0. In this survey, we focus on the vital processes of fault detection, prediction and prevention in Industry 4.0 and present recent developments in ML-based solutions. We start by examining various proposed cloud/fog/edge architectures, highlighting their importance for acquiring manufacturing data in order to train the ML algorithms. In addition, as faults might also occur from sources beyond machine degradation, the potential of ML in safeguarding cyber-security is thoroughly discussed. Moreover, a major concern in the Industry 4.0 ecosystem is the role of human operators and workers. Towards this end, a detailed overview of ML-based human–machine interaction techniques is provided, allowing humans to be in-the-loop of the manufacturing processes in a symbiotic manner with minimal errors. Finally, open issues in these relevant fields are given, stimulating further research.

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We present an actively mode-locked fiber ring laser that uses a single active semiconductor optical amplifier device to provide both gain and gain modulation from an external optical pulse train. The laser source generated 4.3-ps pulses at 20 GHz over a 16-nm tuning range and is stable against environmental changes and simple to build.

Abstract-All-optical clock recovery is demonstrated from pseudo-data patterns at 30 Gb/s. The circuit is based on the optical gain modulation of a semiconductor optical amplifier fiber laser. The recovered clock is a 2.7-ps pulse train, with very low modulation pattern even in the presence of more than 200 consecutive 0's in the data signal.Index Terms-All optical, clock recovery, ring laser, semiconductor optical amplifier.

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