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The magnetic spring is a practical element to isolate external vibration to instruments in ultra-precision manufacturing and ultra-precision testing. Accurate magnetic force and stiffness models are necessary to analyze and optimize the design of magnetic spring isolators. Thus, this study proposes an accurate magnetic force and stiffness model to design and analyze a variable stiffness nonlinear magnetic spring (VSNMS) considering the permanent magnet’s (PM’s) relative permeability, positions, sizes, and magnetic properties. Firstly, the VSNMS’s structure is designed and introduced, and its magnetic force and stiffness models are derived. Secondly, the established model is validated by comparison with the numerical simulation. Thirdly, the VSNMS prototype is fabricated, and then tested through an electronic universal testing machine. The model has the advantage of high accuracy, high efficiency, and ease of use compared with numerical simulations and experimental tests. Furthermore, parametric studies are conducted to learn the effect of PMs’ sizes, positions, and magnetic properties on VSNMS’s magnetic force and stiffness characteristics. Finally, the optimized structural size parameters of VSNMS are obtained using the derived model and the interior-point algorithm. As a result, the established model contributes to the analysis and optimal design of VSNMS, supporting the design of magnetic spring isolators in ultra-precision applications.

Thesecond-generation high-temperature superconductor tape (2G-HTS, also known as a coated conductor) based on REBaCuO (REBa2Cu3O7–δ) exhibits high current density and potential cost-effective price/performance, compared with conventional superconducting materials. Using commercial 2G-HTS tapes, more than a dozen cable vendors had been manufacturing REBCO cables, such as the latest kilometer-class REBCO cable, which was incorporated into a civil grid on December 2021, as part of the record-breaking 35-kV-voltage superconductor cable demonstration project in downtown Shanghai. This paper describes the development of HTS-coated conductors, then outlines the various technological routes for their preparation, reviews the artificial flux pinning of coated conductors, and finally summarizes the technological breakthroughs, the latest research advances, and provides an outlook on their application prospects.

A novel numerical piston-type wave-maker toolbox for the OpenFOAM is developed and demonstrated in this paper. This toolbox is implemented in C++ for improving the solutions of nonlinear wave problems in the field of hydrodynamics. As a toolbox that generates waves using the piston-type method only, it contains several frequently used functions, including the generation and the absorption of waves of various forms, an active absorption system and the porous media flow. Furthermore, to illustrate the operability of the toolbox, some validations and applications are presented, including the regular waves, the irregular waves, and the solitary waves. In each case, a satisfactory agreement is obtained in comparison with the published experimental or theoretical results,so this toolbox may be applied with a considerable confidence.

There is a unique inflorescence composition and stamen structure in Compositae. Stamen structure, filament movement and its mechanism was analyzed and discussed, with cosmos and small sunflowers as experimental materials, by using morphological anatomy, microscopic measurement, tabletting observation. The results showed that: (1) There was a certain regularity in the opening of tubular floral organ in capitulum, of which their movements were initiated from outside to inside. (2) The mainly cause of stamen movement in Compositae came from the changes filaments length. (3) Stamen movement was not a simple physical movement-with filaments shortening, cell structure also has changed. (4) The filament movement in Compositae is not only beneficial to itself fully stretching, but also reduces the interference during pollen spreading.

In this study, a highly sensitive and reliable analytical micro-plate chemiluminescence enzyme immunoassay (CLEIA) based on a monoclonal antibody (McAb) against okadaic acid (OA) was developed and validated for the detection of okadaic acid from a shellfish matrix. A competitive immunocomplex was formed through the binding of an immobilised antigen, OA, in analyzed samples and the McAb against OA. The conjugate OA–BSA was immobilised physically on a polystyrene micro-plate well as a solid phase antigen. Subsequently, free toxins in the analyzed samples competed with the solid phase antigen to bind the McAb against OA. The assay conditions, including the composition and pH of the coating solution, the dilution ratios and amounts of the McAb and the HRP-labelled goat anti-mouse IgG antibody, the time of the antibody-coating, incubation and chemiluminescence reactions and other relevant variables were studied and optimised. The optimised system allowed OA determination in a linear working range from 0.0098–10 μg kg−1(R= 0.99), and the calibration curve obtained for OA revealed a detection limit of 0.0098 μg kg−1. Importantly, the CLEIA was approximately 10 times more sensitive than an ELISA using the same antibody. In addition, the intra- and inter-assay RSDs were both less than 10.0%. Moreover, this method was successfully applied to the evaluation of OA in seashells, with recoveries of 97.2%, 111.2% and 104.7%, respectively, for low-, medium- and high-concentration samples. Good recoveries were obtained from spiked food samples, and the results correlated well with those obtained using conventional indirect competition ELISA, indicating the potential utilisation of the CLEIA as a preliminary screening tool for analyzing OA contamination in shellfish.

More than 30 bending beams with rectangular cross-section and different thicknesses and heights were prepared from Q235 steel. The specimen dimensions were about 240 mm (length) × 60 mm (height) × 70 mm (thickness). Flaws were cut along its middle line with a wire cutter, with lengths ranging from 6 to 35 mm. Each specimen was tested with three-point bend loading, and a process curve was obtained between load and the displacement of the loading point, in order to analyze the fracture process when opening the crack. A deformation near the prefabricated crack was observed in the testing period, and the variation of the fracture characteristic parameters was analyzed for different sizes. For a comprehensive understanding of carbon steel fracture resistance behavior, its elasticity and plasticity were established by determining its Young's modulus and Poisson's ratio with an optical strain gauge. This gauge was also used for the loading process test. It was found that the fracture toughness varied with the dimensions, and the toughness of the elastic limit loading was almost constant. Using the relationship of crack resistance stress intensity factor and fracture criterion, the bearing capacity of the material structure could be estimated, which shows a good agreement with the experimental test data.

More than 30 bending beams with rectangular cross-section and different thicknesses and heights were prepared from Q235 steel. The specimen dimensions were about 240 mm (length) × 60 mm (height) × 70 mm (thickness). Flaws were cut along its middle line with a wire cutter, with lengths ranging from 6 to 35 mm. Each specimen was tested with three-point bend loading, and a process curve was obtained between load and the displacement of the loading point, in order to analyze the fracture process when opening the crack. A deformation near the prefabricated crack was observed in the testing period, and the variation of the fracture characteristic parameters was analyzed for different sizes. For a comprehensive understanding of carbon steel fracture resistance behavior, its elasticity and plasticity were established by determining its Young s modulus and Poisson s ratio with an optical strain gauge. This gauge was also used for the loading process test. It was found that the fracture toughness varied with the dimensions, and the toughness of the elastic limit loading was almost constant. Using the relationship of crack resistance stress intensity factor and fracture criterion, the bearing capacity of the material structure could be estimated, which shows a good agreement with the experimental test data.

In this paper, a 3-dimension finite element with dummy nodes for calculating and outputting the stress energy release (SERR) at the crack tip was built up based on virtual crack closure technique (VCCT), it is presented to demonstrate the virtual crack closure technique has high accuracy and good feasibility. The calculation results curve and the analytical solution curve are in good agreement. The results show that the proposed interface elements can be used to calculate to get accurate results by finite element analysis. It can give us some new ideas for Hydraulic structure crack research.

Parallel harmonic resonance is closely related to the singularity of a node admittance matrix. It was found that the smallest eigenvalue of the matrix defines the mode of parallel harmonic resonance. This paper applies eigenvalue theory and modal sensitivity analysis method to determine which network components contribute significantly to a harmonic resonance phenomenon. Case study results further confirm the theoretical correctness and effectiveness. Thus, this practical method not only provides significant measures for harmonic resonance manage, but also support theoretical and experimental bases for the component parameter design.

In this paper, a fault location method using power quality monitoring data is proposed. The fault location is divided into two classes including fault line recognition and fault distance calculation. Along the each power line in the target network some fictitious fault points are set and the fault voltage of each monitoring bus is calculated. The voltage dip calculation results and the fault line data are matched to form the learning samples and then train the designed fault line recognition BP artificial neural network. The trained neural network searches the fault line when actual fault occurs. After it finishes fault line searching the fault position is calculated using the function of voltage dip amplitude and fault position. The correctness and effectiveness of the proposed method is proved by the simulation results in standard IEEE-14 bus system.

A kind of piezoelectricity acceleration geophone is studied and discussed. carried on its amplitude frequency, phase-frequency characteristic theoretically, obtained the primary factor of the influence on frequency response, and improved in the piezoelectric crystal choice and geophone structure. The theory and the field test result indicated that, this piezoelectricity acceleration geophone has better response characteristic on low frequency and the high-frequency as well as a higher sensitivity, it is one better detection method.

In this paper, it is presented a method of the design and parameter calculation for state variable feedback control system of reheat steam temperature, which based on the mechanism analysis of reheater dynamic characteristics of supercritical 600WM unit. The simulation results show that the control quality and anti-interference ability is better, and the response is faster, while the control system of reheater steam temperature is established with this method.

Harmonic resonance is composed of series and parallel harmonic resonance. It is closely related to the singularity of a network loop impedance matrix or node admittance matrix. It was found that such resonance phenomenon is associated with the singularity of the network matrix. The smallest eigenvalue of the matrix defines the mode of series harmonic resonance. This paper applies this eigenvalue theory and modal sensitivity analysis method to determine which network components contribute significantly to a series harmonic resonance phenomenon. Case study results further confirm the theoretical correctness and effectiveness. Thus, this practical method not only provides significant measures for series harmonic resonance manage, but also support theoretical and experimental bases for the component parameter design.

This paper proposed a voltage dip analyzing method for multiple faults condition in complex power network. This method regarded the fault points as virtual buses and introduced multiple fault position parameters into voltage dip analysis. It expanded the node impedance matrix by calculating the self-impedance of the virtual bus, the mutual impedance between virtual bus and non-fault bus, one virtual bus and another. According to the faults boundary conditions, each fault current phasor was calculated. The fault voltage function of any bus related with the multiple fault position parameters in the power network was derived. The voltage dip analysis result was obtained associated with the voltage dip threshold. The proposed method was validated in the standard IEEE-30 bus system.

This paper discusses the stope parameters of the sublevel subsequent filling stage in Daye Iron Shizishan section. According to the similar material simulation technology, which is the main means, displacement monitoring and internal stress monitoring, several conclusions are summarized as bellow: When the parameter of the room and pillar is 18m, the underground mining is safe and steady. Impacts, which come from different regions’ mining, is different, and the greatest impact comes from the pillar’ mining. Stress monitoring shows that before roof fell down, there is a process of stress concentration. The stress in the roof is shear stress, and compressive stress in the pillar.