Remanufacturing that returns used products to a like-new condition with equivalent warranty to match is an emerging triple-win (environmental, economic and social) industry. Process planning plays a vital role in the success of remanufacturing. However, compared with traditional mass manufacturing, the design of remanufacturing process planning (RPP) is far more complex and time-consuming, heavily depending on the experiences of operators. Since each returned used product, namely the raw materials for remanufacturing, is different, a customized RPP tackling the individuality of returned used products is essential. To this end, the reuse of remanufacturing knowledge from past successful RPP could lead to efficient generation of new process planning for new arrivals. This paper proposes an ontology-based method for knowledge modelling for RPP rapidly. In this method, (1) remanufacturing-ontology provides a unified framework for the management of information and knowledge from various sources.Especially, the remanufacturing knowledge modelling including problem description 2 and problem solution is constructed via a remanufacturing semantic model; (2) Case-Based Reasoning (CBR) method is applied to reuse the knowledge from the most similar previous successful remanufacturing case for the rapid generation of RPP, leading to considerable time and cost saving. An application program is also presented to realize the proposed method. In addition, a case study of crankshaft remanufacturing is carried out to verify the feasibility and efficiency of the proposed method.
The frequency modulation to amplitude modulation (FM-to-AM) effect is one of the few remaining scientific issues in a large-scale laser facility which could prevent fusion ignition. A fiber-based polarization–rotation filter which consists of a fiber polarizer, a section of polarization-maintaining fiber, a half-wave plate and a polarization beam splitter is proposed to suppress the FM-to-AM effect. Theoretical analysis and experimental demonstration in the preamplifier module of the SG-III laser facility prove the effectiveness of this filter.
Laser welding is an indispensable part of competitive manufacturing, but it has a critical issue with energy consumption. The existing literature is limited to the energy supplied to the laser-material interaction for the material welding, and the welding quality is not well considered for energy saving. To reduce the total energy consumption of laser welding without compromising the welding quality, this study investigates the effects of process parameters including the laser power, welding speed and focus position on the specific energy consumption (SEC), welding quality and related energy effectiveness (EE) of the laser welding of 6061 aluminium alloy. The results reveal that adjusting the laser power to improve the welding quality will inevitably lead to a significant increase in the SEC. Energy can be saved with a relatively stable welding quality by varying the welding speed, and the welding quality can be improved without appreciably increasing the energy consumption by setting the focus position to approximately −0.5 mm. The EE can be enhanced with a higher laser power within a moderate welding speed range at the negative focus position. A case demonstrated that with a reasonable process parameter configuration, an energy savings of 12.45% could be realised for laser welding, while the tensile strength was increased by 4.29%, and the weld bead integrity remained stable (a decrease of 0.11%).
We demonstrate an all-PM Er-doped soliton mode-locked fiber oscillator based on the figure-9 configuration with a compact adjustable reflection-type non-reciprocal phase shifter. An analytical model based on the Jones matrix is established to simulate the wavelength tuning phenomenon. Experimentally, it is observed that the increase in pump power results in a significant redshift in the spectrum of output pulses. When the angle of the half-wave plate is rotated in one direction, the output spectrum is redshifted and then blueshifted successively. Good qualitative agreement is presented between the simulations and the experimental results. It is shown that the increase in pump power changes the nonlinear phase shift, which causes the redshift of the transmittance curves at the laser output port. In contrast, the rotation of wave plates not only changes the nonlinear phase shift difference, but also causes variations in linear phase bias and modulation depth. The changes in these parameters lead to the redshift and blueshift of the transmission curves, which enables wavelength tuning.
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