In this paper, the fracture behaviors and interface stresses of sintered Nd-Fe-B magnets were investigated. It was revealed that cracks propagated along the interfaces of Nd2Fe14B/Nd2Fe14B, Nd2Fe14B/Nd-rich phases and...
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In this paper, the fracture behaviors and interface stresses of sintered Nd-Fe-B magnets were investigated. It was revealed that cracks propagated along the interfaces of Nd2Fe14B/Nd2Fe14B, Nd2Fe14B/Nd-rich phases and within Nd-rich phases. The misfits between 2:14:1 and Nd-rich phases were quantitatively determined, reflecting the concentration of interface stresses in magnet. Grain boundaries of magnet were reconstructed by diffusing Tb-containing and Tb-free sources, respectively. The Tb-rich shells at extensive layers of 2:14:1 grains caused lattice distortion, i.e., internal stresses, resulting in the crack mode changing from intergranular to transgranular in near surfaces of Tb-containing diffused magnets. Therefore, the bending strengths were deteriorated although the coercivities were apparently enhanced. In the case of Tb-free Pr-Cu diffused magnet, the Pr and Cu elements were enriched at grain boundaries, and the misfits between 2:14:1 and Nd-rich phases were declined, lowering interface stresses and strengthening grain boundaries. The mechanical and magnetic properties of Pr-Cu diffused magnet were simultaneously improved. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic), (sic)(sic)(sic) Nd2Fe14B/Nd2Fe14B,Nd2Fe14B/(sic)Nd(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Nd(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)2:14:1(sic)(sic)(sic)Nd(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)Tb(sic)(sic)(sic)Tb(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).2:14:1(sic)(sic)(sic)(sic)(sic)(sic)Tb(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic
china is a significant global producer of cement and a major contributor to carbon dioxide emissions within the building materials industry. However, in the context of the prevailing climate change challenges, the cem...
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china is a significant global producer of cement and a major contributor to carbon dioxide emissions within the building materials industry. However, in the context of the prevailing climate change challenges, the cement industry has prioritized energy conservation and carbon reduction as its primary objectives. Solid waste cementing material can be used as an alternative to reduce the emissions and heat generated in the cement industry, thus contributing to the collaborative treatment of solid waste and environmental control. This paper introduces the all-solid waste material as a potential replacement for cement. This material only requires grinding without sintering, its raw materials are all-industrial solid waste, and its production process does not emit any toxic and harmful gases, thus contributing to carbon emission reduction. This material also shows compressive properties and its solidification performance is better than that of standard cement and metals (including lead, cadmium, arsenic, and chromium) and satisfies the drinking water standard (GB 5749-2022). Using the carbon emission accounting method, this study highlights the low-carbon and energy saving properties of the all-solid waste material. This material is also environmentally friendly given its low energy consumption and CO2 emissions, thus providing an avenue for furtherresearch on cement alternatives.
Ionic Liquid Electrospray Thrusters(ILETs)are well suited for micro-nano satellite applications due to their small size,low power consumption,and high specific ***,the limited thrust of a single-emitter ILET restricts...
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Ionic Liquid Electrospray Thrusters(ILETs)are well suited for micro-nano satellite applications due to their small size,low power consumption,and high specific ***,the limited thrust of a single-emitter ILET restricts its use in space *** optimize the performance of ILETs and make them suitable for a widerrange of space missions,we designed a Circular-emitter ILET(CILET)to convert a one-dimensional(point)emission into a twodimensional(line)*** CILET can self-organize multiple Taylor cones *** cones were photographed and the axial emission currents were measured underdifferent voltage and pressure difference conditions with a CILET experimental *** emission can be divided into two stable states and one unstable state based on the flow and current *** current in Stable state Ⅰ increases non-linearly with the voltage,while that in Stable state Ⅱ is nearly linear with respect to the *** number of cones increases with the voltage in stable states,while the cones become short and crowded under high-voltage *** variation law of the number of cones can be explained with the self-organization *** variation in the current exhibits a good correlation with the number of *** study demonstrates the feasibility of circular emitters and experimentally indicates that the emission current is improved by approximately two orders of magnitude compared to that of a single capillary.
The effects of feeding on insect larvae treated with pesticide on the biological and biochemical characteristics of Arma chinensis were investigated. In the F0 generation, the developmental duration and preoviposition...
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The effects of feeding on insect larvae treated with pesticide on the biological and biochemical characteristics of Arma chinensis were investigated. In the F0 generation, the developmental duration and preoviposition period were shortened, the average number of eggs laid was reduced, and the net reproductive rate and mean generation time were significantly lower in the treatment group compared to those in the control group. The average number of eggs laid by the F1 generation of A. chinensis was lower in the treatment group. The intrinsic rates of increase, finite rates of increase and net reproductive rates were significantly lower in the F1 generation in the treatment group than those in the control group. The activities of CarE and GST were significantly induced, while the activity of AChE was inhibited in the A. chinensis in the treatment group. The activities of trypsin and THL were significantly induced in the treatment group, while the activity of LPS was not significantly changed. At the population level, Enterococcaceae were cultured only from the intestines of the A. chinensis in the treatment group. At the genus level, in addition to Serratia, Yokenella and Klebsiella, which were consistent with the control group, the genus Enterococcus was also cultured in the treatment group. When controlling P. rapae in the field, pesticides should be reasonably selected, and an appropriate time should be chosen for the release of A. chinensis to reduce the impact on natural enemies and to achieve synergistic chemical and biological control.
The support technology forroadway rock has always posed significant challenges in mining and tunnel engineering. This is particularly true fordeep asymmetrical soft rock roadway, for which no effective and mature re...
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The support technology forroadway rock has always posed significant challenges in mining and tunnel engineering. This is particularly true fordeep asymmetrical soft rock roadway, for which no effective and mature reference technology currently exists. This paper provides a comprehensive analysis of the deformation mechanism and support technology fordeep soft rock roadway at the Qingyun mine. Based on field investigation and theoretical analysis, we summarize the deformation mechanism and its influencing factors. Numerical simulation results of excavation indicate that the improved support scheme effectively controls roadway deformation, with 68.0 mm for the roof, 26.3 mm for the floor, and 45.12 and 44.98 mm for the two sidewalls. Moreover, the plastic zone depth is significantly reduced by 0.5 m to 2.0 m of roadway. Field monitoring data, including peephole, acoustic velocity, and bolt stress measurement, strongly support the positive impact of the improved support on surrounding rock deformation and stability. As the working face advances, the influence of mining disturbance on the roadway increases. Compared to primary support, the deformation of improved support scheme reduces by 17 to 65 mm. The outline of the loose circle under the improved support scheme is mapped, showing an overall depth reduction of 0.58 and 0.20 m compared to conditions without support and with primary support, respectively. We hope this research serves as a valuable reference for other soft rock engineering projects.
Given the significant greenhouse effect of SF6, the C4F7N-CO2-O-2 mixture has been identified as one of the most promising eco-friendly arc-extinguishing gases. Switching arcs typically exhibit pronounced non-local th...
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Given the significant greenhouse effect of SF6, the C4F7N-CO2-O-2 mixture has been identified as one of the most promising eco-friendly arc-extinguishing gases. Switching arcs typically exhibit pronounced non-local thermodynamic equilibrium (NLTE) phenomena in the peripheral regions and at the current zero-crossing point, thereby influencing the thermophysical properties of the plasma. To investigate the impact of NLTE conditions, the thermodynamic properties and transport coefficients of two-temperature (2-T) C4F7N-CO2-O-2 plasma were calculated under the local chemical equilibrium assumption. The results indicate that NLTE conditions significantly affect the properties of the mixture by altering its composition and particle energy, often having a more substantial impact than pressure variations. The generation of CO plays a critical role in shaping the thermodynamic and transport parameters of the plasma due to its molecular stability, particularly under non-equilibrium states. To maximise the arc-extinguishing performance of the gas, recommended oxygen mixing ratios are proposed. The results provide fundamental data for 2-T magnetohydrodynamic modelling of C4F7N gas mixtures in arc simulations.
This paper presents a thermal properties analysis model of angular contact ball bearings considering thermal-mechanical coupling structure deformations. The correlation between the assembly state and structure flexibl...
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This paper presents a thermal properties analysis model of angular contact ball bearings considering thermal-mechanical coupling structure deformations. The correlation between the assembly state and structure flexible deformations for the shaft-bearing-pedestal system is derived, and an improved transient thermal network model considering cage guiding type and grease heat transfer process is constructed. The influencing mechanism of bearing thermal properties is revealed, and the variations of structure deformations and service performance compared to those cases without considering thermal effect are explored. results indicated that the deformations of the shaft and bearing ring are more sensitive to the thermal effect, which is significantly greater than those cases without considering the thermal effect. The thermal expansion induced by temperature rise intensifies the bearing structure deformations, anddecreases bearing clearance and the design contact angle. The bearing deformations are positively correlated with the rotation speed and external loads, and the bearing thermal characteristics can be optimized by properly adjusting the assembly state of the rotor-bearing system.
A time-fractional diffusion problem with a Caputo time-fractional derivative of order alpha is an element of (0, 1) is considered, the solution of which is typically weakly singular at the initial time. For this probl...
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A time-fractional diffusion problem with a Caputo time-fractional derivative of order alpha is an element of (0, 1) is considered, the solution of which is typically weakly singular at the initial time. For this problem, we give an H-1-norm analysis of the stability and convergence of an integral-averaged L1 method on nonuniform time meshes. The averaging of the L1 scheme that we use is known as the L1(+) or L1rline> scheme. A new positive definiteness result for the integral-averaged L1 fractional-derivative operator is established. It improves the previous positive definiteness results in the literature and plays an important role in the analysis of H-1-norm error of the integral-averaged L1 method. The H-1-norm stability holds for the general nonuniform time meshes, while the H-1-norm convergence is proved for the time graded meshes and the H-1-norm convergence order in time is min{3 + alpha, gamma alpha}/2 for all alpha is an element of (0, 1), where gamma >= 1 is the mesh grading parameter. Two full discretization methods using finite differences and finite elements in space are considered. The theoretical results are illustrated by numerical results.
despite the adverse impacts of occupational fatigue such as accidents and injuries in the manufacturing industry, it has not been systematically examined in the literature on production scheduling. In this paper, we i...
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despite the adverse impacts of occupational fatigue such as accidents and injuries in the manufacturing industry, it has not been systematically examined in the literature on production scheduling. In this paper, we integrate the classic bio-mathematical fatigue prediction model from the brain science literature into the simple single machine scheduling problem with sequence-dependent setup times. Then, we formulate the problem as a mixed-integer linearprogramming model and propose an adaptive large neighborhood search heuristic. The effectiveness of the heuristic is numerically validated through real cases. Finally, we argue that considering bio-mathematical fatigue prediction can lead to safer production schedules, notably reducing the fatigue working hours in ourreal case.
Traditional blinddeconvolution algorithms perform well in estimating the repetition rate of impulses within signals;however, they fall short in preserving the original features of the signal. In engineering applicati...
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Traditional blinddeconvolution algorithms perform well in estimating the repetition rate of impulses within signals;however, they fall short in preserving the original features of the signal. In engineering applications, particularly for cyclic impulse signals, maintaining signal fidelity is as crucial as accurately estimating impulse counts, making pure impulse count estimation insufficient for practical needs. To address this limitation, we propose a novel deconvolution algorithm-maximum correlation Pearson fidelity coefficient deconvolution (MCPSFd). This method constructs an objective function based on two key metrics: the correlation Pearson coefficient (CPC), which quantifies the periodicity of impulses, and the signal fidelity coefficient (SFC), which measures the similarity between the original andrecovered signals. By combining CPC and SFC, we introduce a new objective function, termed the correlated Pearson fidelity factor (CPSF), which simultaneously considers both the number of impulses and the original characteristics of the filtered signal without introducing redundant parameters. The MCPSFd algorithm is derived by maximizing the CPSF function. Extensive experiments on simulated and measured bearing signals demonstrate that the proposed method significantly outperforms existing deconvolution algorithms in recovering periodic impulses and minimizing signal distortion.
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