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Electromagnetic forming (EMF) is a high-speed forming process with significant potential for manufacturing bipolar plates. However, titanium's low conductivity requires the use of a driver sheet in traditional EMF, limiting its formability improvement. This study proposed a novel electromagnetic forming method with independent loading of the magnetic field and current (EMF-ILMFC), enabling separate application of electromagnetic force and Joule heating. The dynamic deformation behavior of ultra-thin titanium was investigated using three different loading methods: quasi-static (QS), electromagnetic bulging with driver sheets (EMB-DS), and electromagnetic bulging with the new method (EMB-ILMFC). The study revealed that the forming limit under EMB-ILMFC was significantly higher than under EMB-DS and QS, with a maximum improvement of 139.1%. Numerical simulations and experimental analyses were conducted to elucidate the thermal effects on formability during dynamic deformation. The results indicate that thermal effects reduce flow stress, extend the duration of inertia and high strain rates, and thereby improve the formability of titanium.

The magnetic immiscible copper matrix alloys are extensively industrial applications due to their comprehensive properties such as high strength, high conductivity, high thermal conductivity and excellent magnetic permeability. Here, we investigated the effects of the addition of Co and Al elements on the microstructural evolution of magnetic Cu–Fe alloys (CFAs) and comprehensive properties after annealing under the static magnetic field (SMF). The results show that the microalloying was effective in enhancing the mechanical and magnetic properties but negative for the electric conductivity. The addition of Co element significantly suppressed the grains recrystallization of CFAs during the annealing process and improved the thermal stability of CFAs. Al elements homogeneously dispersed in the sample. SMF facilitated the nucleation and precipitation processes of the secondary precipitated particles in the Cu-rich matrix through the introducing the extra magnetic Gibbs free energy and also promoted the structural transformation of the secondary precipitated particles from FCC to BCC. This work indicates that SMF can be effectively used to modify the magnetic materials with exceptional comprehensive properties during the solid state phase transformation process. It also provides valuable guidance for the development of novel materials with superior comprehensive performance.

Abstract REBCO has been used extensively as coated conductors applied to superconducting magnets due to its exceptional superconducting properties. As a REBCO superconductor, YbBa2Cu3O7−y (Yb123) has a low melting temperature, making it suitable for use as an intermediate medium connector while preparing the superconducting joint. However, there is still uncertainty about the formation mechanism of Yb123 and the synthesis of this superconductor has not been fully understood. Therefore, this study systematically investigated the phase transformation process of Yb123 during heat treatment in flowing oxygen. The results indicated that Yb123 sample with the highest phase purity could be obtained by annealing at 927 °C or 937 °C but not in between, respectively. Furthermore, a quantitative phase analysis revealed that the sample annealed at 937 °C had a phase purity greater than 80 wt%. Additionally, a strong c-axis texture was observed in the bulk Yb123 superconductor prepared at 937 °C. Meanwhile, the superconducting results revealed that the bulk sample’s Tc was 89.9 K, and its self-field critical current densities at 4.2 K and 77 K were 1.3 × 105 A/cm2 and 5.0 × 103 A/cm2, respectively. Based on the results mentioned above, the phase transformation process and formation mechanism of Yb123 in flowing oxygen were elaborated.

Abstract In this paper, we proposed a sliding mode control method for the bearingless permanent magnet slice motor for the blood pump based on the genetic particle swarm algorithm, which aims to solve the problems of strong coupling, strong interference, nonlinearity and uncertainty. Firstly, the mathematical model of rotor torque and suspension force of the bearingless permanent magnet slice motor is established. Secondly, the structure of sliding mode observer is deduced by designing sliding mode surface and control law. And, the performance parameters of sliding mode observer are optimized by the genetic particle swarm optimization algorithm. Thirdly, electromagnetic torque and suspension force control under this control method is studied by Simulink. Finally, the control method is applied to the control of the blood flow of the blood pump, and the rotation speed can effectively control the blood flow. The results indicate that compared with PID control and traditional sliding mode control methods, the sliding mode control method optimized by the genetic particle swarm optimization algorithm greatly improves the control performance of bearingless permanent magnet slice motor. The results show that the blood flow can meet expectations with a small error, which fully meets the blood perfusion requirements of the blood pump.

Van der Waals (vdW) heterojunctions, with their unique electronic and optoelectronic properties, have become promising candidates for photodetector applications. Amplifying the contribution of the depletion region in vdW heterojunction, which would enhance both of the collection efficiency and speed of the photogenerated carriers, presents an effective strategy for achieving high performance vdW heterojunction photodetectors. Herein, a fully depleted vdW heterojunction photodetector is built on two-dimensional (2D) semiconductor materials (GaTe and InSe) layered on a pattered bottom electrode in vertical structure, in which the generation and motion of carriers are exclusively achieved in the depletion region. Attributed to the intrinsic built-in electric field, the elimination of series resistance and the depletion region confinement of carriers, the as-fabricated photodetector exhibits prominent photovoltaic properties with a high open-circuit voltage of 0.465 V, as well as photoresponse characteristics with outstanding responsivity, detectivity and photoresponse speed of 63.7 A/W, 3.88 × 1013 Jones, and 32.7 μs respectively. The overall performance of this fully depleted GaTe/InSe vdW heterojunctions photodetectors are ranking high among the top level of 2D materials based photodetectors. It indicates the device architecture can provide new opportunities for the fabrication of high-performance photodetectors.

Dendrites play a crucial role in the microstructure of single crystal superalloys, predominantly developing along the [001] orientation. The mechanical performance is greatly influenced by the uniform distribution of dendrites. During the solidification process, we frequently observe instances of dendrites deviating from the [001] orientation, resulting in tilted structures. These deviations give rise to both aligned and misaligned arrays within the transverse section. The study comprehensively examines the homogeneity of tilted dendritic structures. As solidification progresses, new dendrites within the aligned array tend to maintain a hexagonal structure. Simultaneously, the remaining metastable structures gradually transition into hexagonal structures. In contrast, various polygons mutually transform in misaligned array, resulting in a dynamic adjustment of their proportions. Consequently, the aligned array exhibits a higher proportion of hexagonal structures and a more uniform dendrite spacing compared to the misaligned array. Within the transitional region, an increase in heptagonal structures leads to heightened non-uniformity in dendrite spacing. The predominance of hexagonal structures can be attributed to their more uniform solute distribution, facilitated by the characteristics of the aligned array, which promote hexagonal structure formation by adjusting the solute field distribution. On the other hand, due to the random positioning of dendrites in the misaligned array, various stacking structures coexist in dynamic equilibrium. The research reveals an intrinsic relationship between macroscopic array patterns, stacking structures, dendrite spacing, and microscopic solute distribution. These findings provide a theoretical foundation for the production of high-quality single crystal dendritic structures and offer insights into their influence on material properties.

In recent years, karst construction projects in the built-up area of Wuhan (capital of Hubei Province, China) are increasing, and the karst geological disasters have aroused social concerns. The actual engineering projects usually use shallow geophysical exploration methods to explore karst. This paper uses Spatial Auto-Correlation Method (SPAC) and electromagnetic Computerized Tomography (CT) to detect karst in urban built-up areas. Depending on the different physical properties of rock and soil, the SPAC method can better reveal the interface between soil and rock strata and the interface between soil layers. The electromagnetic CT method can identify strata according to the apparent absorption coefficient, which can better reveal the interface between soil and rock, the interface between the more intact and weathered rock. The SPAC method is mainly qualitative to measure the low-speed area, namely, the wrong geological body i.e., karst cave, but also can detect the fracture zone or filling mode of karst cave, and at the same time, cannot use exploration holes or logging observation. The electromagnetic CT method can accurately detect the location and scale of the karst caves and has a higher accuracy detecting karst bands. In addition, exploration holes or well logging observations are also expected to be conducted, and their detection effect is greatly affected by lithology.

The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging (MRI) magnets requires the careful management of exogenous heat sources. A strongly shielded gradient magnetic field is important for the optimal operation of cryogen-free MRI systems. In this study, we present an enhanced shielding method incorporating a regionalized stray field constraining strategy. By optimizing the constraint parameters, we could develop engineering-feasible gradient coil schemes without increasing system complexity but with the stray field intensity reduced by half. In real measurement in an integrated MRI system, the developed gradient assembly demonstrated good performance and supported to output images of excellent quality. Our findings suggested that the proposed method could potentially form a useful design paradigm for cryogen-free MRI magnets.

Centrifugal blood pumps are important devices used to treat heart failure. However, they are prone to high-risk suction events that pose a threat to human health when operating at high speeds. To address these issues, a normal suction detection method and a suction suppression method based on the FFT-GAPSO-LSTM model and speed modulation were proposed. The innovation of this suction detection method lies in the application of the genetic particle swarm optimisation (GAPSO) and the fast Fourier transform (FFT) feature extraction method to the long-term and short-term memory (LSTM) model, thereby improving the accuracy of suction detection. After detecting signs of suction, the suction suppression method designed in this study based on variable-speed modulation immediately takes effect, enabling the centrifugal blood pump to quickly return to its normal state by controlling the speed. The suction detection method was divided into four steps. First, a mathematical model of the coupling of the cardiovascular system and the centrifugal blood pump was established, and a real-time blood flow curve was obtained through model simulation. Second, the signal was preprocessed by adding Gaussian white noise and low-pass filtering to make the blood flow signal close to actual working conditions while retaining the original characteristics. Subsequently, through fast Fourier transform (FFT) analysis of the processed curve, the spectral characteristics that can characterise the working state of the centrifugal blood pump were extracted. Finally, the parameters of the LSTM model were optimised using the GAPSO, and the improved LSTM model was used to train and test the blood flow spectrum feature set. The results show that the suction detection method of the FFT-GAPSO-LSTM model can effectively detect whether centrifugal blood pump suction occurs and has certain advantages over other methods. In addition, the simulation results of the suction suppression were excellent and could effectively suppress the occurrence of suction. These results provide a reference for the design of centrifugal blood pump control systems.

At present, HTS magnets cannot operate in the real closed-loop persistent current mode due to the existence of joint resistance, flux creep, and AC loss of the HTS tape. Instead of using a current source, HTS flux pumps are capable of injecting flux into closed HTS magnets without electrical contact. This paper presents a practical superconducting DC dynamo for charging a conduction-cooled HTS magnet system based on a flux-pumping technique. To minimize heat losses, the rotor is driven by a servo motor mounted outside the vacuum dewar by utilizing magnetic fluid dynamic sealing. Different parameters, such as air gap and rotating speed, have been tested to investigate the best pumping effect, and finally, it successfully powers a 27.3 mH HTS non-insulated double-pancake coil to the current of 54.2 A within 76 min. As a low-cost and compact substitute for the traditional current source, the realization of a contactless DC power supply can significantly improve the flexibility and mobility of the HTS magnet system and could be of great significance for the technological innovation of future HTS magnets used in offshore wind turbines, biomedical, aerospace, etc.

Introduction: Titanium (Ti) and Ti-based alloy materials are commonly used to develop artificial hearts. To prevent bacterial infections and thrombus in patients with implanted artificial hearts, long-term prophylactic antibiotics and anti-thrombotic drugs are required, and this may lead to health complications. Therefore, the development of optimized antibacterial and antifouling surfaces for Ti-based substrate is especially critical when designing artificial heart implants.Methods: In this study, polydopamine and poly-(sulfobetaine methacrylate) polymers were co-deposited to form a coating on the surface of Ti substrate, a process initiated by Cu2+ metal ions. The mechanism for the fabrication of the coating was investigated by coating thickness measurements as well as Ultraviolet–visible and X-ray Photoelectron (XPS) spectroscopy. Characterization of the coating was observed by optical imaging, scanning electron microscope (SEM), XPS, atomic force microscope (AFM), water contact angle and film thickness. In addition, antibacterial property of the coating was tested using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as model strains, while the material biocompatibility was assessed by the antiplatelet adhesion test using platelet-rich plasma and in vitro cytotoxicity tests using human umbilical vein endothelial cells and red blood cells.Results and discussion: Optical imaging, SEM, XPS, AFM, water contact angle, and film thickness tests demonstrated that the coating was successfully deposited on the Ti substrate surface. The biocompatibility and antibacterial assays showed that the developed surface holds great potential for improving the antibacterial and antiplatelet adhesion properties of Ti-based heart implants.

The morphology of the solid-liquid (S-L) interface is crucial for the directionally solidified microstructures of various alloys. This paper investigates the effect of vertical high magnetic field (VHMF) on the morphology evolution of the S-L interface and the solidified microstructure during the directional solidification of Zn-2wt.%Bi immiscible alloy. The results indicate that the morphology of the S-L interface is highly dependent on the VHMF, resulting in various solidified microstructures. When the growth rate was 1 μm/s, the aligned droplets were formed directly at the disturbed S-L interface under a 1 T VHMF. However, the stability of the S-L interface was improved to form a stable Bi-rich fiber under a 5 T VHMF. When the growth rate was 5 μm/s, the S-L interface was changed from cellular to dendritic to cellular again with increasing magnetic flux density. A theory regarding constitutional supercooling and efficient solute diffusion has been proposed to explain the S-L interface transition under the VHMF. The difference in the effective diffusion capacity of the solute originates from the thermoelectric magnetic effect and the magneto-hydrodynamic damping effect. The present work may initiate a new method to transform the solidified microstructures of immiscible alloys via an applied magnetic field during directional solidification.

Al-20wt.%Si hypereutectic alloys were designed in order to study how a high static magnetic field (HSMF) during annealing affected the microstructure evolution, atomic diffusion, and resultant mechanical properties from the microscale to the atomic scale. Our results indicate that the size of the primary silicon particles (PSPs) increased with increasing temperature, while it decreased with increasing magnetic flux density (MFD). The solid solubilities of the Al matrix were 0.84 wt% and 0.53 wt% for the ribbons annealed at 0 T and 8 T, respectively. HSMF decreased the precipitation rate of Al from the PSPs and retained the solute trapping effect in the PSPs during annealing. After annealing the ribbon, the Al matrix retained the lattice distortions under the HSMF. Applying a HSMF led to the coexistence of grain boundary strengthening, particle strengthening, dislocation strengthening, and solid solution strengthening, so the hardness and elastic modulus increased with increasing MFD. Compared with the ribbon annealed at 8 T, the ribbon annealed at 0 T had a hardness and elastic modulus improved by 139.47% and 1053.2%, respectively. This paper presents a new way to design heat treatments and even solidification processes for metallic materials by controlling their diffusion by applying an HSMF. Keywords: Melt spinning, Annealing, High static magnetic field, Nanoindentation, Coarsening, Diffusion

Due to their convenience, water measuring structures have become an important means of measuring water in irrigation canal systems However, relevant research on upstream and downstream water-depth monitoring point locations is scarce. Our study aims to determine the functional relationship between the locations of the water-depth monitoring points and the opening width of the sluice. We established 14 trunk-channel and branch-channel hydrodynamic models. The locations of the water-depth monitoring points for the upstream and downstream reaches and their hydraulic characteristics were assessed using a numerical simulation and hydraulic test. The results showed that the locations of the upstream and downstream water-depth monitoring points were, respectively, 16.26 and 15.51 times the width of the sluice. The average error between the calculated flow rate and the simulated value was 14.37%; the average error between the flow rates calculated by the modified and the simulated values was 3.36%. To further verify the accuracy of the modified discharge calculation formula, by comparing the measured values, we reduced the average error of the modified formula by 19.29% compared with the standard formula. This research provides new insights into optimizing water measurements in irrigation canal systems. The results provide an engineering basis for the site selection of water-depth monitoring points that is suitable to be widely applied in the field.

In this study, boron powder with different particle sizes was purified by both chemical and heat treatment methods. The reduction in the particle size can improve the chemical purification with no effort on the heat treatment. The superconducting properties of the powder drastically changed even with only a partial elimination of oxygen. On the one hand, less oxygen content resulted in high Tc and Jc values under the low magnetic field, and most importantly, a significant improvement in the superconducting connectivity (Af value). On the other hand, the degradation of Jc under a high field and a change in the pinning mechanism were also found, along with decreasing oxygen. This result indicated that oxygen, probably MgO, might act as the pinning center and as an obstacle for the supercurrent in MgB2 at the same time. This work paves the way for obtaining pure oxygen-free MgB2 and understanding the real effect of oxygen in MgB2.

The Three Gorges Reservoir is a good site for the further researches on reservoir induced seismicity due to decades' seismic monitoring. After the first water impounding in 2003, seismic activity becomes more frequent than that before water impoundment. In order to quantitatively study, the relationship between the water level fluctuation and earthquakes in TGR, we introduced statistical methods to attain the goal. First of all, we relocated the earthquakes in TGR region with double difference method and divided the earthquakes into 5 clusters with clustering analysis method. Secondly, to examine the impacts of water level fluctuation in different water filling stages on the seismic activity in the 5 clusters, a series of statistical analyses are applied. Pearson correlation results show that only the 175 m water level fluctuation has significantly positive impacts on the seismic activity in clusters Ⅰ, Ⅱ, Ⅲ and Ⅴ with correlation coefficients of 0.44, 0.38, 0.66 and 0.63. Cross-correlation analysis demonstrates that 0, 1, 0 and 0 month time delay separately for the clusters Ⅰ, Ⅱ, Ⅲ and Ⅴ exists. It illustrated the influences of the water loading and pore pressure diffusion on induced earthquakes. Cointegration tests and impulse response analysis denoted that the 175 m water level only had long term and significant effects just on the seismic events in the intersection region of the Fairy Mount Fault and Nine-brook Fault. One standard deviation shock to 175 m water level increased the seismic activity in cluster Ⅴ for the first 3 months, and then the negative influence was shown. After 7 months, the negative impulse response becomes stable. The long-term effect of the 175 m water impoundment also proved the important role of pore pressure diffusion in RIS with time.

According to groundwater level monitoring data of Shuping landslide in the Three Gorges Reservoir area, based on the response relationship between influential factors such as rainfall and reservoir level and the change of groundwater level, the influential factors of groundwater level were selected. Then the classification and regression tree (CART) model was constructed by the subset and used to predict the groundwater level. Through the verification, the predictive results of the test sample were consistent with the actually measured values, and the mean absolute error and relative error is 0.28 m and 1.15% respectively. To compare the support vector machine (SVM) model constructed using the same set of factors, the mean absolute error and relative error of predicted results is 1.53 m and 6.11% respectively. It is indicated that CART model has not only better fitting and generalization ability, but also strong advantages in the analysis of landslide groundwater dynamic characteristics and the screening of important variables. It is an effective method for prediction of ground water level in landslides.

On 25 April, 2015, an Mw7.9 earthquake occurred in Nepal, which caused great economic loss and casualties. However, almost no surface ruptures were observed. Therefore, in order to interpret the phenomenon, we study the rupture process of the earthquake to seek answers. Inversion of teleseismic body-wave data is applied to estimate the rupture process of the 2015 Nepal earthquake. To obtain stable solutions, smoothing and non-negative constraints are introduced. 48 teleseismic stations with good coverage are chosen. Finite fault model is established with length and width of 195 km and 150 km, and we set the initial seismic source parameters referring to CMT solutions. Inversion results indicate that the focal mechanism of this earthquake is a thrust fault type, and the strike, dip and rake angle are in accordance with CMT results. The seismic moment is 0.9195 × 1021 Nm (Mw7.9), and source duration is about 70 s. The rupture nucleated near the hypocenter and then propagated along the dip direction to the southeast, and the maximum slip amounts to 5.2 m. Uncertainties on the amount of slip retrieved by different inversion methods still exist, the overall characteristics are inconsistent. The lack of shallow slip during the 2015 Gorkha earthquake implies future seismic hazard and this region should be paid more attention to.

In this work, the effect of cold rolling and heat treatment upon the microstructure and texture of the surface layer and cross-section of Ni5W alloy substrate was analyzed via the EBSD technique. A typical copper deformation texture was shown by the cold-rolled Ni5W alloy substrate. The cube-oriented nuclei were attributed to the rolling direction−transverse direction (RD-TD) plane due to the presence of copper and S rolling textures. Typical large-shape cold-rolled microstructure was presented by the RD-ND surface in the cube-oriented area. During the recrystallization process, the cube-oriented grains did not have a nucleation quantity advantage, but they did have an obvious growth advantage compared with other orientation grains. They can form a strong cube texture by absorbing the random orientation and rolling orientation through the migration of large-angle grain boundaries.

ErBa2Cu3O7−δ (Er123) superconductor is one of the best candidates of superconductor solder for the fabrication of superconducting joint between GdBa2Cu3O7−δ (Gd123) coated conductor, due to its high Tc value (93 K) and highest optimized oxygen annealing temperature among RE123 compounds. In this paper, we systematically research the effect of sintering parameters on the phase formation, microstructure and superconducting properties of Er123 powder. The optimized synthesis route to acquire high purity Er123 powder with as good superconducting properties as Gd123 has been uncovered. The melt temperature of Er123 with different dopant compared to Gd123 is also investigated, and the feasible operating temperature range of Er123 superconductor solder is discussed. This work reveals a very important starting point on fabrication high-quality superconducting joint between the commercial Gd123 coated conductor, which can further improve the development of the persistent operating mode on ultra-high field nuclear magnetic resonance and magnetic resonance imaging.

In the past few decades, the multifunctional magnetic drug carrier based on the magnetic nanoparticles and high magnetic field has been intensively researched. The magnetic drug carrier can be targeted to the tumour area not only by the chemical protocol but also by the physical one (external field). In this review, the authors first briefly discuss the fabrication process of magnetic drug carriers, which includes the synthesis of magnetic nanoparticles, fabrication of magnetic drug carriers and conjugation of anti-tumour agents. Then different targeted protocols have been summarised, including passive targeting, biochemical active targeting and biophysical active targeting namely magnetic targeting (MT). Multiple MT results both in vitro and in vivo are introduced, in which two unconventional cases are emphasised and described. The first MT clinical research with 14 peoples was performed in the last century. A 0.5–0.8 T permanent magnet was attached to the tumour area when magnetic particles conjugated with epirubicin were injected. The side effect of epirubicin had been decreased, and the four patients showed the decreasing of a tumour which proved the feasibility of MT. Different from other targeting protocols, MT needs an extra external magnetic field. So various types of MT instruments have been shown in the final part of this review, including a single strong magnetic field, homemade electronic solenoid coil assay and commercial magnetic resonance imaging.

Joint inversion of teleseismic body-wave data and strong ground motion waveforms was applied to determine the rupture process of the 2010 Mentawai earthquake. To obtain stable solutions, smoothing and non-negative constraints were introduced. A total of 33 teleseismic stations and 5 strong ground motion stations supplied data. The teleseismic and strong ground motion data were separately windowed for 150 s and 250 s and band-pass filtered with frequencies of 0.001–1.0 Hz and 0.005–0.5 Hz, respectively. The finite-fault model was established with length and width of 190 km and 70 km, and the initial seismic source parameters were set by referring to centroid moment tensor (CMT) solutions. Joint inversion results indicate that the focal mechanism of this earthquake is thrust fault type, and the strike, dip, and rake angles are generally in accordance with CMT results. The seismic moment was determined as 5.814 × 1020 Nm (Mw7.8) and source duration was about 102 s, which is greater than those of other earthquakes of similar magnitude. The rupture nucleated near the hypocenter and then propagated along the strike direction to the northwest, with a maximum slip of 3.9 m. Large uncertainties regarding the amount of slip retrieved using different inversion methods still exist; however, the conclusion that the majority of slip occurred far from the islands at very shallow depths was found to be robust. The 2010 Mentawai earthquake was categorized as a tsunami earthquake because of the long rupture duration and the generation of a tsunami much larger than was expected for an earthquake of its magnitude.

Through the Three Gorges well network, we examine different coseismic changes in water temperature caused by local earthquakes since 2008, and offer a mechanistic explanation. The relations between the coseismic changes in water temperature and the parameters of distant and local earthquakes are deduced.

Based on studying organizational structure of Construction Green Supply Chain Management (CGSCM), a mathematical programming model of CGSCM was proposed. The model aimed to maximize the aggregate profits of normalized construction logistics, the reverse logistics and the environmental performance. Numerical experiments show that the proposed approach can improve the aggregate profit effectively. In addition, return ratio, subsidies from governmental organizations, and environmental performance were analyzed for CGSCM performance. Herein, the proper return, subsidy and control strategy could optimize construction green supply chain.

An unfitted discontinuous Galerkin method is proposed for the elliptic interface problems. Based on a variant of the local discontinuous Galerkin method, we obtain the optimal convergence for the exact solution u in the energy norm and its flux p in the L2 norm. These results are the same as those in the case of elliptic problems without interface. Finally, some numerical experiments are presented to verify our theoretical results.