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Metal ions doping is a typical approach for tuning sensing properties of metal oxide semiconductors based gas sensors. Herein, hierarchical flower-like pure and In-doped Co3O4 nanostructures assembled by porous two dimensional (2D) nanosheets are synthesized via a solvothermal method and annealing process. The sensing measurements display that the In@Co3O4-4 based sensor possesses high response values of 55.9 toward 100 ppm xylene at 150 ℃, which are nearly 3.8 times larger than that of pure Co3O4 sensor. Furthermore, it possesses good selectivity and anti-humidity properties. Combined with the results of DFT calculations, the mechanism of enhanced gas sensing performance is analyzed systematically.

The existence of bond exchange reactions and covalent adaptable networks (CANs) in thermoset epoxy has facilitated its self-healing and reversible mechanical capabilities. However, the toughening mechanisms and cooperative coupling of these crystal phases and CANs in a semi-crystalline thermoset epoxy have not been well understood. In this study, a Hamiltonian graph model is formulated to examine toughening mechanisms in the semi-crystalline thermoset epoxy based on the vertices and paths, both of which are employed to describe the crystalline phases and CANs, respectively. A free-energy equation is also developed based on the tail and tie free energy functions to investigate the cooperative coupling of crystal phases and CANs. The crystal phases increase the cross-linking density of the CANs, which helps the crystal phases with a homogeneous dispersion. Moreover, an extended Maxwell model is developed along with the Hamiltonian graph to explore the coupling effect of crystal phase and CAN on the mechanical behaviors of semi-crystalline thermoset epoxy. A constitutive stress–strain relationship is then proposed to describe the self-healing and toughening behaviors of semi-crystalline thermoset epoxy. The stress–strain relationship of semi-crystalline polymers, which incorporates crystal phases and CANs, has been thoroughly investigated using the analytical results obtained from the proposed Hamiltonian graph model. Finally, the effectiveness of the proposed model is verified using the finite element analysis method and a set of experimental data.

The broad spectrum near unity solar absorber shows important significance in the solar energy conversion. In this work, a polarization independent broadband and wide-angle metamaterials solar absorber consisted of VO2 periodic arrays and alternately stacked SiO2/W layers is designed. To explore the absorption of solar radiation and proper geometric parameters, numerical studies are carried out on the proposed structure. And the absorption of the designed structure is above 90% in the spectra range of 300-2000 nm with an average absorption of 95%. Moreover, the proposed structure possesses excellent solar absorptivity and insensitivity to the incident angle and polarization of sunlight. The average integrated absorption remains 90% with the light incident angle of 50°. Hence, the proposed broadband solar absorber has potentially valuable applications in thermophotovoltaic conversion, thermal emitters, solar cell, and so on.

After running for a long time, isolator switches are prone to be covered with dirt and corrosion. Switch cleaning is necessary for good operation and safety. Laser cleaning technology for rust removal is emerging in recent years. This paper introduces the technical principles of laser cleaning for rust removal in detail, designs a specific process scheme and takes a steel plate sample cleaning and rust removal as a case. The application effect of laser cleaning and rust removal technology is tested and shows that the technology analyzed in this paper can play a great cleaning effect without damaging the equipment base.

The timely and regularly clean for long-time use disconnecting switches are important for prolonging their lifetime. Laser cleaning for metal rust has the advantage of zero pollution. Fast speed and parameters can be adjusted to various sites. This paper introduces the development of laser cleaner for rust on disconnecting switches. Comparing results under different parameters in labs and sites, this paper concludes that when the laser power is 20W and the scanning speed is 2500mm/s, the device has a better cleaning effect.

We investigated femto- and picosecond-time magnetization dynamics in a ferromagnetic Ni80Fe20 film with varying thicknesses (wedge-shaped film). We observed that the thickness gradient strongly affects the magnetic moment distribution, causing a magnetization reorientation from in-plane to out-of-plane, and formatting a stripe domain (SD) at the thicker end of the wedge. The magnetization dynamics measurements reveal that the part of the film displaying SDs follows a substantially faster demagnetization and magnetization recovery and smaller magnetization quenching compared to the in-plane domain film. The experiments and micromagnetic simulations support that the decrease in relaxation time is caused by a magnetic anisotropy of the films introduced by SD formation. Our results point out that the micromagnetic structure plays an important role in the magnetization dynamics in ferromagnetic films after optically triggered demagnetization.

PM2.5 is a well-known airborne hazard to cause various diseases. Evidence suggests that air pollution exposure contributes to the occurrence of pulmonary nodules. Pulmonary nodules detected on the computed tomography scans can be malignant or progress to malignant during follow-up. But the evidence of the association between PM2.5 exposure and pulmonary nodules was limited. To examine potential associations of exposures to PM2.5 and its major chemical constituents with the prevalence of pulmonary nodules. A total of 16 865 participants were investigated from eight physical examination centers in China from 2014 to 2017. The daily concentrations of PM2.5 and its five components were estimated by high-resolution and high-quality spatiotemporal datasets of ground-level air pollutants in China. The logistic regression and the quantile-based g-computation models were used to assess the single and mixture impact of air pollutant PM2.5 and its components on the risk of pulmonary nodules, respectively. Each 1 mg m−3 increase in PM2.5 (OR 1.011 (95% CI: 1.007–1.014)) was positively associated with pulmonary nodules. Among five PM2.5 components, in single-pollutant effect models, every 1 μg m−3 increase in organic matter (OM), black carbon (BC), and NO3 − elevated the risk of pulmonary nodule prevalence by 1.040 (95% CI: 1.025–1.055), 1.314 (95% CI: 1.209–1.407) and 1.021 (95% CI: 1.007–1.035) fold, respectively. In mixture-pollutant effect models, the joint effect of every quintile increase in PM2.5 components was 1.076 (95% CI: 1.023–1.133) fold. Notably, NO3 − BC and OM contributed higher risks of pulmonary nodules than other PM2.5 components. And the NO3 − particles were identified to have the highest contribution. The impacts of PM2.5 components on pulmonary nodules were consistent across gender and age.These findings provide important evidence for the positive correlation between exposure to PM2.5 and pulmonary nodules in China and identify that NO3 − particles have the highest contribution to the risk.

The effects of radio frequency (RF) atmospheric pressure (AP) He/H2 plasma and thermal treatment on the hydrogenation of TiO2 thin films were investigated and compared in this work. The color of the original TiO2 film changes from white to black after being hydrogenated in He/H2 plasma at 160 W (gas temperature ∼381 °C) within 5 min, while the color of the thermally treated TiO2 film did not change significantly even in pure H2 or He/H2 atmosphere with higher temperature (470 °C) and longer time (30 min). This indicated that a more effective hydrogenation reaction happened through RF AP He/H2 plasma treatment than through pure H2 or He/H2 thermal treatment. The color change of TiO2 film was measured based on the Commission Internationale d’Eclairage L*a*b* color space system. Hydrogenated TiO2 film displayed improved visible light absorption with increased plasma power. The morphology of the cauliflower-like nanoparticles of the TiO2 film surface remained unchanged after plasma processing. X-ray photoelectron spectroscopy results showed that the contents of Ti3+ species and Ti–OH bonds in the plasma-hydrogenated black TiO2 increased compared with those in the thermally treated TiO2. X-ray diffraction (XRD) patterns and Raman spectra indicated that plasma would destroy the crystal structure of the TiO2 surface layer, while thermal annealing would increase the overall crystallinity. The different trends of XRD and Raman spectra results suggested that plasma modification on the TiO2 surface layer is more drastic than on its inner layer, which was also consistent with transmission electron microscopy results. Optical emission spectra results suggest that numerous active species were generated during RF AP He/H2 plasma processing, while there were no peaks detected from thermal processing. A possible mechanism for the TiO2 hydrogenation process by plasma has been proposed. Numerous active species were generated in the bulk plasma region, accelerated in the sheath region, and bumped toward the TiO2 film, which will react with the TiO2 surface to form OVs and disordered layers. This leads to the tailoring of the band gap of black TiO2 and causes its light absorption to extend into the visible region.

As a two-dimensional (2D) material, monolayer MoS2 which limits its optical applications has a low absorption efficiency. In this paper, we propose a three-band perfect metamaterial absorber in the visible light range based on monolayer MoS2. The peak absorptivity of the structure at each resonance wavelength is nearly perfect, moreover, the light absorption of monolayer MoS2 is obviously enhanced at the three resonant wavelengths. The dielectric–dielectric–metal structure we designed produces the coupling of Fabry–Perot resonance and high-order diffraction guided-mode resonance at different absorption peaks, which has been proved by the slab waveguide theory. In addition, the multi-modal absorption phenomenon is explained by extracting the equivalent impedance. The results show that we can adjust the absorption peak wavelength by regulating the parameters of the structure. This structure not only provides an idea for enhancing the interaction between light and two-dimensional materials but also has potential applications for optical detection devices.

Frequency-comb emission via high-order harmonic generation (HHG) provides an alternative method for the coherent vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) radiation at ultrahigh repetition rates. In particular, the temporal and spectral features of the HHG were shown to carry profound insight into frequency-comb emission dynamics. Here we present an ab initio investigation of the temporal and spectral coherence of the frequency comb emitted in HHG of He atom driven by few-cycle pulse trains. We find that the emission of frequency combs features a destructive and constructive coherences caused by the phase interference of HHG, leading to suppression and enhancement of frequency-comb emission. The results reveal intriguing and substantially different nonlinear optical response behaviors for frequency-comb emission via HHG. The dynamical origin of frequency-comb emission is clarified by analyzing the phase coherence in HHG processes in detail. Our results provide fresh insight into the experimental realization of selective enhancement of frequency comb in the VUV–XUV regimes.

We report a compact experimental setup for producing a quantum degenerate mixture of Bose 23Na and Fermi 40K gases. The atoms are collected in dual dark magneto–optical traps (MOT) with species timesharing loading to reduce the light-induced loss, and then further cooled using the gray molasses technique on the D 2 line for 23Na and D 1 line for 40K. The microwave evaporation cooling is used to cool 23Na in | F = 2,mF = 2〉 in an optically plugged magnetic trap, meanwhile, 40K in | F = 9/2,mF = 9/2〉 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where 23Na atoms are immediately transferred to |1,1〉 for further effective cooling to avoid the strong three-body loss between 23Na atoms in |2,2〉 and 40K atoms in |9/2,9/2〉. At the end of the evaporation in optical trap, a degenerate Fermi gas of 40K with 1.9 × 105 atoms at T/TF = 0.5 in the |9/2,9/2〉 hyperfine state coexists with a Bose–Einstein condensate (BEC) of 23Na with 8 × 104 atoms in the |1,1〉 hyperfine state at 300 nK. We also can produce the two species mixture with the tunable population imbalance by adjusting the 23Na magneto–optical trap loading time.

The asymmetric saddle-shape warpage is one of the hardest limitations on the development of three-dimensional integrated circuits (3D ICs) as the vertical integration increases. To improve the product yield, an effective method for saddle-shape warpage reduction in 3D IC production by backside patterning laser annealing treatment with a multilayer structure is investigated in this work. The reduction of saddle-shaped warpage by patterning laser treatment is the first time in 3D NAND array wafer application and through simulations and experiments, the laser annealing pattern is determined. In addition, the materials of the multilayer structure are selected as amorphous Al2O3 and TiN according to experiments and theoretical analysis. As a result, a conformal 47.8 µm optimization of the saddle-shape warpage is successfully reached in a control wafer test by patterning laser annealing treatment.

For mobile terminal users in the process of moving, due to the uncertainty of movement, how to effectively predict and reasonably allocate the Edge Servers (ESs) for mobile terminal users has become the key to solving the problem. Therefore, this paper proposes and designs a mobile terminal user mobility prediction method based on an Unscented Kalman Filter (UKF). According to the application scenario of Mobile Edge Computing (MEC), the edge server with computing resources is placed at the edge node of the network. The state equation and observation equation are constructed through the trajectory points of the mobile terminal users, and the trajectory prediction is completed using the UKF. By comparing the No Filter. Method, the Linear Kalman Filter. Method and the UKF method, the research results show that the proposed method can effectively reduce the error and improve the success rate of the task compared with the other two methods so that the prediction trajectory of mobile terminal users is more accurate and more applicable.

The critical parameters of the liquid-gas phase transition of symmetric nuclear matter are computed using the Brueckner-Hartree-Fock method at finite temperature by employing different realistic nucleon-nucleon potentials. Temperature effects on single-particle potentials, defect functions, and three-body forces are discussed in detail. Results obtained from the full procedure and frozen-correlations approximation are compared. We find critical temperatures of approximately 14 to 19 MeV and critical densities in the range of to , depending on the interactions employed.

After the B-phase of the 500kV transformer was replaced, the three-phase voltage on the 35kV low-voltage side was imbalanced and the neutral point displacement voltage was relatively high during the start-up test. For this problem, firstly, the calculation method of neutral point displacement voltage is given through the method of vector analysis and equivalent circuit, and the reasons for the imbalance of the three-phase voltage are analyzed. According to the measured parameters, the PSCAD/EMTDC power system simulation software is used to establish a model, and the steady-state operating characteristics of the system are simulated and calculated. Theoretical analysis and simulation calculation have determined that the cause of the imbalance of the three-phase voltage is the inconsistency between the ground capacitance of the low-voltage winding and the capacitance between the high-voltage and low-voltage windings of the B-phase transformer than that of the A-phase and C-phase. The impact of the capacitance between the high-voltage and low-voltage windings of the transformer is far greater than the capacitance of the low-voltage windings to ground on the imbalance of three-phase voltage to ground on the low-voltage side of the transformer.

A magnetic tunnel junction (MTJ) is the core component in memory technologies, such as the magnetic random-access memory, magnetic sensors and programmable logic devices. In particular, MTJs based on two-dimensional van der Waals (vdW) heterostructures offer unprecedented opportunities for low power consumption and miniaturization of spintronic devices. However, their operation at room temperature remains a challenge. Here, we report a large tunnel magnetoresistance (TMR) of up to 85% at room temperature (T = 300 K) in vdW MTJs based on a thin (< 10 nm) semiconductor spacer WSe2 layer embedded between two Fe3GaTe2 electrodes with intrinsic above-room-temperature ferromagnetism. The TMR in the MTJ increases with decreasing temperature up to 164% at T = 10 K. The demonstration of TMR in ultra-thin MTJs at room temperature opens a realistic and promising route for next-generation spintronic applications beyond the current state of the art.

In oil-immersed transformers, the insulation performance of transformer oil is a key factor for the normal operation of transformers. In order to explore the performance of transformer oil under different micro-water content conditions in a low-temperature environment, this paper builds a low-temperature experimental platform with a minimum temperature of -50 °C and selects the commonly used 45# oil as the test oil. Four properties including conductivity and dielectric properties were tested. The research results show that the viscosity of transformer oil increases exponentially with the decrease of temperature, the thermal conductivity first decreases and then increases with the decrease of temperature, the relative dielectric constant increases approximately linearly with the decrease of temperature, and the micro-water content increases. It has little effect on the above three properties; the electrical conductivity and dielectric loss of transformer oil with different micro-water content both increase first and then decrease with the decrease of temperature, and with the increase of micro-water content, the corresponding peak temperature also increased.

The behavior of H in β-Ga2O3 is of substantial interest because it is a common residual impurity that is present in β-Ga2O3, regardless of the synthesis methods. Herein, we report the influences of H-plasma exposure on the electric and optical properties of the heteroepitaxial β-Ga2O3 thin films grown on sapphire substrates by chemical vapor deposition. The results indicate that the H incorporation leads to a significantly increased electrical conductivity, a greatly reduced defect-related photoluminescence emission, and a slightly enhanced transmittance, while it has little effect on the crystalline quality of the β-Ga2O3 films. The significant changes in the electrical and optical properties of β-Ga2O3 may originate from the formation of shallow donor states and the passivation of the defects by the incorporated H. Temperature dependent electrical properties of the H-incorporated β-Ga2O3 films are also investigated, and the dominant scattering mechanisms at various temperatures are discussed.

We experimentally realize two-dimensional (2D) single-layer ultracold gases of 87Rb by dynamically tuning the periodicity of a standing wave, known as accordion lattice. In order to load 87Rb Bose–Einstein condensate into single dark fringe node of the blue detuning optical lattice, we reduce the lattice periodicity from 26.7 μm to 3.5 μm with the help of an acousto-optic deflector (AOD) to compress the three-dimensional BEC adiabatically into a flat and uniform quasi-2D single-layer. We describe the experimental procedure of the atoms loading into the accordion lattice in detail and present the characteristics of the quasi-2D ultracold gases. This setup provides an important platform for studying in- and out-of equilibrium physics, phase transition and 2D topological matter.

Defect detection of a workpiece surface is a basic and essential task in the production of products. Although significant progress has been made in workpiece surface defect detection, traditional methods still find it difficult to detect small defects efficiently. To deal with this problem, we propose an efficient small defect detection network with a novel parallel convolution module, serial convolution module and feature fusion module. First, a lightweight backbone network is used to extract the preliminary defect features. Second, the parallel convolution module and serial convolution module are used to obtain the abundant defect features. Then, the feature fusion module is used to fuse the shallow features with deep features, to enhance the features of the small defects. Finally, the obtained features are put into the corresponding detection head to get the final prediction results. The experimental results on a local cable dataset and a public printed circuit board dataset show that our method achieves a remarkable performance in detecting small defects and achieves a favorable trade-off between accuracy, speed and model size, which meets the requirements of industrial applications.

We demonstrate that dual dark magnetic-optical-traps (MOTs) have great importance in the two-species 87Rb and 40K mixture compared with dual bright MOTs. The dark MOT has a little improvement in the trapping of single-species 87Rb or 40K gases compared with bright MOT. For the case of loading two-species 87Rb and 40K simultaneously, the improvement of 40K in the dual dark MOTs is mainly from the reduction of light-assisted collision losses. The dual dark MOTs employ a pair of conical lenses to produce the hollow beam for repump laser with high efficiency. The number and density of 87Rb and 40K atoms after evaporative cooling in the hybrid magnetic trap with dark MOT loading are compared with those in bright MOT. The atoms with large number and high density make it easier to realize the quantum degenerate of Bose–Fermi mixture.

All-electrical driven magnetization switching attracts much attention in next-generation spintronic memory and logic devices, particularly in magnetic random-access memory (MRAM) based on the spin–orbit torque (SOT), i.e. SOT-MRAM, due to its advantages of low power consumption, fast write/read speed, and improved endurance, etc. For conventional SOT-driven switching of the magnet with perpendicular magnetic anisotropy, an external assisted magnetic field is necessary to break the inversion symmetry of the magnet, which not only induces the additional power consumption but also makes the circuit more complicated. Over the last decade, significant effort has been devoted to field-free magnetization manipulation by using SOT. In this review, we introduce the basic concepts of SOT. After that, we mainly focus on several approaches to realize the field-free deterministic SOT switching of the perpendicular magnet. The mechanisms mainly include mirror symmetry breaking, chiral symmetry breaking, exchange bias, and interlayer exchange coupling. Furthermore, we show the recent progress in the study of SOT with unconventional origin and symmetry. The final section is devoted to the industrial-level approach for potential applications of field-free SOT switching in SOT-MRAM technology.

We have studied the field-effect carrier transport of graphene on 4H silicon carbide substrate. In order to extract the electrical parameters, the top-gated field effect transistor has been fabricated. By fitting the measured results with Kim’s model, the field effect carrier mobility (µ) and the metal/graphene contact resistance (Rc) and the residual carrier concentration (n0) are derived to be 3382cm2/Vs, 2250Ω▪µm and 2.18×1013cm-2, respectively. It is noted that the large contact resistance did not affect the high field effect carrier mobility of our device. The high carrier mobility suggests that the SiC epitaxial graphene may be quite suitable for the future high speed electronic applications.

In order to meet the requirements of high reliability and economy of space launch vehicle control system, a heterogeneous redundancy method of flight control computer based on mutual exclusion and spin mechanism is proposed in this paper. This method avoids common cause failure mode and improves hardware resource utilization efficiency by resolving redundancy. The reliability and economy of the launch vehicle control system can be improved without increasing the cost of volume and weight.

To reveal the performance of primary frequency regulation of the 600MW sub-critical thermal power units in a wide load range and accurately simulate the process, the primary frequency regulation performance of a 600MW sub-critical thermal power unit was studied with a wide load ranging from 20% to 90% under rated conditions. The model of steam turbine in BPA was modified in consideration of steam pressure and the valve throttling effect. The primary frequency regulation performance of the unit was simulated with the modified model. The research results show that the primary frequency regulation performance of the thermal power unit is poor at low load and the results of simulation with the modified model are highly consistent with the tested data due to consideration of steam pressure and valve throttling effect, meaning that the model can be used to simulate the primary frequency regulation of the thermal power unit with wide load operation accurately.

Transportation services are diversifying as the demand for logistics services and truck transportation increases. However, the subcontracting hierarchy has produced social problems such as excessive driver labor, dissatisfaction of recipients, and deterioration of distribution efficiency. In this study, we focused on these problems and proposed, designed, implemented, and verified a point-to-point (P2P)-type logistics platform that reflects user preferences. A P2P logistics platform is defined as a decentralized platform in which delivery schedules are made only by interactions between truck and package agents without any human intervention. This platform is based on logistics agent modeling and sacrifice volume and negotiation, and its construction and simulation are described. In addition, as a case study, the model’s effectiveness for time-insensitive cargo, the case of truck entry and exit for time-sensitive cargo, and the actual delivery and truck supply convergence were verified.

Position and attitude change during sit to stand transfer is the most important change in daily life. On the basis of fully studying the existing equipment, position and attitude during sit to stand transfer is analysed, and the mathematical model of this process is established, the motion trajectory of hip joint during sit to stand transfer is normalized, then the feature points are extracted from motion trajectory. Based on the feature points, and using the linkage mechanism, the dimension synthesis of linkage mechanism is completed by graphic method, the method of realizing anthropomorphic motion trajectory during sit to stand transfer is given systematically based on linkage mechanism. The simulation results show that the designed mechanism can realize the anthropomorphic motion trajectory accurately during sit to stand transfer, and it lays a good foundation for the subsequent design of sit to stand assistance equipment.

Based on the traditional gray GM (1, N) model, with seven kinds of gas fusion in transformer oil predicted, the actual detection times for the gas is less, the sequence accuracy is greatly reduced with an large error, and it will not conform to the standard judgment for the smooth curve. Therefore, an adaptive regression algorithm is proposed to revise each calculation result of its GM model to modify the model error. Through simulation, the sequence curves of the N data by error correction are obviously closer with a greater correlation degree. The improved gray prediction model can effectively improve the accuracy of traditional GM (1, N).

In recent years, with the rapid development of technology, mobile robots are being applied in all aspects of production and life. The A* algorithm can be used for global path planning of mobile robots. Aimed at the problem of the traditional A* algorithm planning path having many turning points and do not satisfying the global optimality, an A* algorithm based on the adaptive neighborhood search and steering cost has been proposed. Based on the information of the surrounding obstacles, the algorithm adaptively selects the appropriate neighborhood to search for the optimal child node. By establishing the steering cost model of the mobile robot, the steering cost is joined into the evaluation function of the A* algorithm. Based on the adaptive neighborhood search, the A* algorithm with steering cost breaks through the constraint of eight neighborhood search nodes, shortens the path length, and uses the steering cost to search for the global optimal path with fewer turning points. The simulation results show that compared to the traditional A* algorithm, the total path cost of the A* algorithm based on adaptive neighborhood search and steering cost is reduced by 19.3%, and the number of turning points is reduced by 44.4%.