Influence of stress on the stray field signals of ferromagnetic materials

To investigate the influence of stress alone on the stray field signals of ferromagnetic materials,the static tensile tests of 0.45%C steel and 45CrNiMoVA steel flat-shaped specimens were performed on an MTS810 hydraulic testing machine. Hp（y） signals,the normal component of spontaneous stray field,were measured during the testing process by an EMS-2003 metal magnetic memory diagnostic apparatus cooperated with a non-magnetic electric control displacement instrument. Fracture and microstructure were observed by a scanning electronic microscope and a transmission electron microscope,respectively. The relationships between axial applied stress or residual stress measured by X-ray diffraction method and Hp（y） were analyzed. The results indicate that some regular pattern of the magnetic curve is displayed only between applied stress and stray field signals. The magnetic ordering process stops due to dislocation pinning magnetic domain structure,and Hp（y） value unvaried nearly with applied load increasing in the plastic deformation stage.

The Integrals of Entwining Structure

In this paper the integrals of entwining structure (A,C,ψ) are discussed, where A is a k-algebra, C a k-coalgebra and a k-linear map. We prove that there exists a normalized integral γ:C→Hom(C,A) of (A,C,ψ) if and only if any representation of (A,C,ψ) is injective in a functorial way as a corepresentation of C. We give the dual results as well.

Fatigue features study on the crankshaft material of 42CrMo steel using acoustic emission

Crankshaft is regarded as an important component of engines, and it is an important application of remanufacturing because of its high added value. However, the fatigue failure research of remanufactured crankshaft is still in its primary stage. Thus, monitoring and investigating the fatigue failure of the remanufacturing crankshaft is crucial. In this paper, acoustic emission （AE） technology and machine vision are used to monitor the four-point bending fatigue of 42CrMo, which is the material of crankshaft. The specimens are divided into two categories, namely, pre-existing crack and non-pre- existing crack, which simulate the crankshaft and crank- shaft blank, respectively. The analysis methods of para- meter-based AE techniques, wavelet transform （WT） and SEM analysis are combined to identify the stage of fatigue failure. The stage of fatigue failure is the basis of using AE technology in the field of remanufacturing crankshafts. The experiment results show that the fatigue crack propagation style is a transgranular fracture and the fracture is a brittle fracture. The difference mainly depends on the form of crack initiation. Various AE signals are detected by parameter analysis method. Wavelet threshold denoising and WT are combined to extract the spectral features of AE signals at different fatigue failure stages.

Microstructure,magnetic domain and dynamic loss of surface-textured Fe-based nanocrystalline alloy

Heterogeneous coarse surface crystallites induced in the industrial Fe-rich nanocrystalline alloy is an obstacle for high-frequency and high-power commercial applications.Herein,the phase,crystal orientation,nanostructure and magnetic domain evolution of the surface-crystallized Fe-rich alloy were systematically investigated.Microstructure and inverse pole figures analysis confirms that the DOordered dendriticcrystallites bear<001>-oriented fiber texture before and after annealing at the free surface,while ultrafine nanocrystals are randomly oriented in the interior and wheel surface after annealing.As compared to zero magnetic-field-annealing,the transverse magnetic-field-annealing induces weakly oriented fiber texture and relatively uniform dendritic-crystallites at the surface,and uniform anisotropy in the interior and surface,which promotes smooth wall motion at the surface and magnetization rotation in the interior.This synergetic effect reduces the excess loss and leads reduction in dynamic loss at 1.0 T and10 kHz by 36%.

Response surface regression analysis on FeCrBSi particle in-flight properties by plasma spray

This work discusses the interactive effects between every two of argon flow rate, voltage, and spray distance on in-flight particles by plasma spray and constructs models that can be used in predicting and analyzing average velocity and temperature. Results of the response surface methodology show that the interactive effects between voltage and spray distance on particle in- flight properties are significant. For a given argon flow rate, particle velocity and temperature response surface are obviously bending, and a saddle point exists. With an increase in spray distance, the interactive effects between voltage and argon flow rate on particle in-flight properties appear gradually and then weaken. With an increase in voltage, the interactive effects between spray distance and argon flow rate on particle in-flight properties change from appearing to strengthening and then to weakening.

Resonance Mechanism Analysis of Large-scale Photovoltaic Power Plant

To analyze the resonance mechanism of a photovoltaic(PV)power plant,a simplified impedance model of the PV power plant is first established.The structure of the PV power plant is then introduced,and the reason for the resonance is obtained by analyzing the on-site situation and measured data of the PV power plant.Finally,a simple and effective solution is proposed based on the structure of the PV power plant and its existing facilities.The results of the engineering experiments and the stable operation of the PV power plant verify the effectiveness of the proposed method.

Novel Wind Power Grid-connection System Using Inductive Filtering Technology

Herein,a novel wind power grid-connection system based on inductive filtering is proposed to improve grid-connection compatibility,and is implemented in a 50-MW real system.First,the topology and wiring configuration of the proposed system are discussed.Thereafter,an equivalent circuit and mathematical model are established to reveal the filtering characteristics and resonance damping mechanism of the proposed system.Finally,a 50-MW wind farm-based experimental study,which is conducted to validate the effectiveness and availability of the system is discussed.The experimental results show that the main harmonics,power factor,voltage fluctuation,and flicker satisfy national standards.