Development of Space-Time-Controlled Multi-Stage Pulsed Magnetic Field Forming and Manufacturing Technology at the WHMFC*

In November 2011, the Project of Basic Research of Forming by Space-Time-Controlled Multi-Stage Pulsed Magnetic Field (Stic-Must-PMF) was supported by the National Basic Research Program of China (973 Project, 2011.11-2016.08). It is aimed at achieving breakthroughs in manufacturing technology to solve current problems in forming largescale and complex sheet and tube parts and components, imposed by the limitations of existing equipment and materials forming properties. The objective of our research group focuses on the design principles and structural layout optimization of Stic-Must-PMF facility. And this paper will report the development of Stic-Must-PMF forming and manufacturing technology at the Wuhan National High Magnetic Field Center (WHMFC) including numerical modeling, experimental setup and experimental studies

Evaluation of Agricultural Eco-Efficiency and Its Spatiotemporal Differentiation in China, Considering Green Water Consumption and Carbon Emissions Based on Undesired Dynamic SBM-DEA

Both agricultural output and environmental pollution in China show certain characteristics of spatiotemporal variation due to the evolution and inter-provincial disparities of resource endowment, economic development level, and production mode. This paper considered the green water consumption, carbon emissions in agricultural production, and the persistent role of fixed asset investment, constructed an undesired dynamic SBM-DEA model, and evaluated the agricultural eco-efficiency (AEE) of 31 provinces in China from 2007 to 2018, analyzing the spatiotemporal differentiation. The results show that, during 2007–2018, the following can be concluded: (1) The AEE of 31 provinces in China showed the characteristics of an overall stable rise from 0.64 to 0.70 but uneven development among regions from 2007 to 2018. (2) The averages of either the agricultural resource consumption efficiency index or pollution emission efficiency index in 31 provinces slightly increased over time, while the average value of the agricultural fixed asset investment efficiency index showed a decline in volatility. The spatial discrepancy of any index mainly stems from the index disparity between groups with a high AEE and groups with a low one, with contribution rates of more than 85%. (3) It is recommended to emphasize strengthening communication and cooperation between provinces with high and low AEE and implement distinct regional strategies to improve AEE

Dielectric, piezoelectric, and ferroelectric properties of Al2O3 and MnO2 modified PbSnO3-PbTiO3- Pb(Mg1/3Nb2/3)O3 ternary ceramics

The PbSnO3-PbTiO3-Pb(Mg1/3Nb 2/3)O3 (PST-PMN) ternary system with morphotropic phase-boundary (MPB) compositions were fabricated using a two-step columbite precursor method. The effects of Al2O3 and MnO2 addition on the dielectric, piezoelectric, and ferroelectric properties of PST-PMN were investigated. MnO2 acted as an acceptor dopant and induced a hardening effect in PST-PMN, with decreased piezoelectric coefficients d33 and increased mechanical quality factors Q m, while the addition of Al2O3 led to the significant decrease of piezoelectric properties, attributed to the second phase. Of particular interest is the fact that the Mn-doped PST-PMN exhibited excellent properties when the doping level was in the range of 0.2-0.5 wt%, with piezoelectric d33, planar electromechanical coupling kp, dielectric permittivity Ïμr, Qm, remnant polarization Pr and coercive field EC being on the order of ∼510 pC N-1, ∼57%, 3120-3500, 530-600, 27-30 μC cm -2, and ∼8 kV cm-1, respectively, showing advantages over commercial PZT4-type ceramics, which are promising for high-power electromechanical applications. 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Mechanical Behaviors of Polymer-Based Composite Reinforcements within High-Field Pulsed Magnets

The development of pulsed magnets capable of generating magnetic fields exceeding 100 Tesla has been recognized as a crucial pursuit for advancing the scientific research on high magnetic fields. However, the operation of magnets at ultra-high magnetic fields often leads to accidental failures at their ends, necessitating a comprehensive exploration of the underlying mechanisms. To this end, this study investigates, for the first time, the mechanical behaviors of Zylon fiber-reinforced polymers (ZFRPs) within pulsed magnets from a composite perspective. The study begins with mechanical testing of ZFRPs, followed by the development of its constitutive model, which incorporates the plasticity and progressive damage. Subsequently, in-depth analyses are performed on a 95-T double-coil prototype that experienced a failure. The outcomes reveal a notable reduction of approximately 45% in both the radial and axial stiffness of ZFRPs, and the primary reason for the failure is traced to the damage incurred by the end ZFRPs of the inner magnet. The projected failure field closely aligns with the experiment. Additionally, two other magnet systems, achieving 90.6 T and 94.88 T, are analyzed. Finally, the discussion delves into the impact of transverse mechanical strength of the reinforcement and axial Lorentz forces on the structural performance of magnets

Effect of Sn Content on the Phase Structure and Electrical Properties of PbSnO3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 Ternary Ceramics

PbSnO3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PSn-PMN-PT) ternary ceramics were successfully prepared by two-step columbite precursor method. The effects of Sn content on the phase structure and electrical properties of PSn-PMN-PT were investigated. X-ray powder diffraction (XRD) results indicated that all studied PSn-PMN-PT compositions located around the morphotropic phase boundary (MPB), with rhombohedral and tetragonal phases coexisted. With the decrease of Sn content, no change was observed in the XRD patterns of PSn-PMN-PT, while pyrochlore phase presented with excess Sn. The piezoelectric, dielectric and ferroelectric properties of PSn-PMN-PT were found to be improved with deficient Sn and deteriorate with increasing Sn content. In particular, the optimum piezoelectric and ferroelectric properties were achieved for PSn-PMN-PT ceramics with 0.2mol% deficient Sn, i.e. d(33)=similar to 530 pC/N, k(p)=similar to 56.4%, Q(m)=similar to 570, epsilon(r)=similar to 3070, tan delta=similar to 0.3%, P-r=similar to 28.9 mu C/cm(2) and E-c=similar to 8 kV/cm. Effect of Sn Content on the Phase Structure and Electrical.... Available from: https://www.researchgate.net/publication/273678929_Effect_of_Sn_Content_on_the_Phase_Structure_and_Electrical_Properties_of_PbSnO3-PbMg13Nb23O3-PbTiO3_Ternary_Ceramics [accessed Jun 15 2018]