Local functional features in stamped components have been studied in detail due to unique advantages in saving individual parts, reducing maintenance costs, and realizing weight reduction. The ...present investigation focuses on the plastic forming process of the structure of multi-bosses including non-central symmetrical bosses and tri-bosses, typical local functional features. The technical route draws from a previous study on a central boss by the compression-drawing method and the extension to multi-bosses is built on a hybrid experimental–numerical approach with A1050 aluminum sheet. The results show that for the structure of non-central symmetrical bosses, radial location
I
of the boss structure is confirmed as a significant factor in boss forming, influencing not only the height but also the cross-section of the boss structure, and the value of
I
being 8 mm is proven to be the optimum solution for the given boss structure. Under the same deformation conditions, the degree of plastic deformation in the forming process of the tri-bosses structure is much higher than that in non-central symmetrical bosses due to the new cavity of the central boss and the height of the non-central boss in the tri-bosses structure is lower than that in non-central symmetrical bosses as a result of the absorption of the central boss. Moreover, fracture failure around the punch radius will occur when the maximum value of radial tensile stress exceeds the sheet tensile strength.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Color centers in solids, such as the nitrogen-vacancy center in diamond, offer well-protected and well-controlled localized electron spins that can be employed in various quantum technologies. ...Moreover, the long coherence time of the surrounding spinful nuclei can enable a robust quantum register controlled through the color center. We design pulse sequence protocols that drive the electron spin to generate robust entangling gates with these nuclear memory qubits. We find that compared to using Carr-Purcell-Meiboom-Gill (CPMG) alone, Uhrig decoupling sequence and hybrid protocols composed of CPMG and Uhrig sequences improve these entangling gates in terms of fidelity, spin control range, and spin selectivity. We provide analytical expressions for the sequence protocols and also show numerically the efficacy of our method on nitrogen-vacancy centers in diamond. Our results are broadly applicable to color centers weakly coupled to a small number of nuclear spin qubits.
From first-principles calculations, we proposed a silicon germanide (SiGe) analog of silicene. This SiGe monolayer is stable and free from imaginary frequency in the phonon spectrum. The electronic ...band structure near the Fermi level can be characterized by Dirac cones with the Fermi velocity comparable to that of silicene. The Ge and Si atoms in SiGe monolayer exhibit different tendencies in binding with hydrogen atoms, making sublattice-selective hydrogenation and consequently electron spin-polarization possible.
Uniaxial tensile tests were conducted to investigate the hot tensile deformation behavior of 6061 aluminum alloy under various temperatures and strain rates. Fields−Backofen equation was employed to ...establish the constitutive model of 6061 aluminum alloy, which was used to construct the finite element model for multi-bosses formed by plate forging process at elevated temperature. In the combination of numerical simulations and experimental tests including micro-hardness and electron back-scattered diffraction (EBSD) examination, the influence of two main process parameters, namely deformation temperature and counter-punch force, on the boss deformation and microscopic characteristics of multi-bosses formed at elevated temperature was discussed. The results show that the constitutive equation adopted is adequate to predict the deformation behavior in the plate forging process. While a higher temperature can improve the formability due to the reduction of plastic deformation resistance, a higher counter-punch load is favorable to increase the boss height and risk of fracture around the punch radius at the same time. In addition, it is favorable to promote recrystallization and fabricate the cylindrical component with a more homogeneous microstructure at a higher deformation temperature. From a comprehensive consideration, the 623 K is taken as the optimized deformation temperature for the selected 6061 aluminum alloy.
To minimize the earing incurred by the planar anisotropic properties of sheets, a non-uniform die clearance model was proposed for the cup drawing process. The theoretical earing profile height model ...with non-uniform die clearance was developed based on the combination of radial strain and thickness strain. The Hill 1948 yield criteria was applied to predict geometric earing profile and the anisotropic parameters were calibrated by optimization. It is observed that the predictions of the theoretical model are in agreement with the results of the cup drawing experiments, and the earing profile height is increasingly decreased by the non-uniform die clearance model. Further to this, a numerical model of the deep drawing process was also carried out using the commercial finite element software Abaqus. The results show that the cup drawing with non-uniform die clearance can not only minimize the earing profile height but also reduce the opening springback and twist springback in the split-ring process.
Predicting the quality of a rubber compound is a necessity for intelligent mixing. However, the conventional quality prediction based on the power curve has low precision and significant dispersion, ...making it challenging to satisfy the need for real-time rubber mixing quality inspection. In this research, the vibration signals were collected for the first time as an input feature of the mixing quality prediction model, with carbon black dispersion is utilized as a quality index. On the basis of the theory of deep learning, the online quality prediction model of mixing was constructed using a variety of featured extraction methods and neural network structures, and the models were compared and tested. After 5 experiments, the average root mean square error (RMSE) of convolutional neural network-long short-term memory network (CNN-LSTM) model is 0.1160, which is 21.46% higher than that of LSTM model after time-domain featured extraction, demonstrating the efficacy and superiority of CNN-LSTM end-to-end model. This study is essential for the progression and breakthrough of the real-time mixing quality optimization issue.
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Silicon carbide (SiC)-based defects are promising for quantum communications, quantum information processing, and for the next generation of quantum sensors, as they feature long coherence times, ...frequencies near the telecom, and optical and microwave transitions. For such applications, the efficient initialization of the spin state is necessary. We develop a theoretical description of the spin-polarization process by using the intersystem crossing of the silicon vacancy defect, which is enabled by a combination of optical driving, spin-orbit coupling, and interaction with vibrational modes. By using distinct optical drives, we analyze two spin-polarization channels. Interestingly, we find that different spin projections of the ground state manifold can be polarized. This paper helps in understanding initialization and readout of the silicon vacancy and explains some existing experiments with the silicon vacancy center in SiC.
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Graphene was the first material predicted to realize a topological insulator (TI), but unfortunately the gap is unobservably small due to carbon's weak spin-orbital coupling (SOC). Based on ...first-principles calculations, we propose a stable sp-sp(2) hybrid carbon network as a graphene analog whose electronic band structures in proximity of the Fermi level are characterized by Dirac cones. We demonstrate that this unique carbon framework has topologically nontrivial electronic structures with the Z2 topological invariant of v = 1 which is quite promising for hosting the quantum spin Hall effect (QSHE) in an experimentally accessible low temperature regime (<7 K). This provides a viable approach for searching for new TIs in 2D carbon allotropes.
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