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Manipulating sign-reversible Berry phase effects is both fundamentally intriguing and practically appealing for searching for exotic topological quantum states. However, the realization of multiple Berry phases in the magneto-valley lattice is rather challenging due to the complex interactions from spin-orbit coupling, band topology, and magnetic ordering. Here, taking single-layer spin-valley RuCl2 as an example, we find that sign-reversible Berry phase transitions from ferrovalley (FV) to half-valley semimetal (HVS) to quantum anomalous valley Hall effect (QAVHE) can be achieved via tuning electronic correlation effect or biaxial strains. Remarkably, QAVHE phase, which combines both the features of quantum anomalous Hall and anomalous Hall valley effect, is introduced by sign-reversible Berry curvature or band inversion of d xy /d x 2-y 2 and d z 2 orbitals at only one of the K/K' valleys of single-layer RuCl2. And the boundary of QAVHE phase is the HVS state, which can achieve 100% intrinsically valley polarization. Further, a k·p model unveiled the valley-controllable sign-reversible Berry phase effects. These discoveries establish RuCl2 as a promising candidate to explore exotic quantum states at the confluence of nontrivial topology, electronic correlation, and valley degree of freedom.

We have developed an X-ray Ti/Au transition-edge sensor (TES) with an Au absorber deposited on the center of TES and improved its energy resolution using K-means clustering algorithm in combination with Wiener filter. We firstly extract the main parameters of each recorded pulse trace, which are adopted to classify these traces into several clusters in K-Means clustering algorithm. Then real traces are selected for energy resolution analysis. Following the baseline correction, the Wiener filterer is used to improve the signal-to-noise ratio. Although the silicon underneath the TES has not been etched to reduce the thermal conductance, the energy resolution of the developed X-ray TES was improved from 94 eV to 44 eV@5.9 keV.

The high wastage rate and low survival rate of seed cells in conventional bone tissue engineering (BTE) are always a challenge for tissue regeneration. Constructing scaffolds that could continuously recruit endogenous stem cells is considered a novel way to promote tissue repair. In this study, a GelMA fiber hydrogel membrane loaded interleukin 8 (IL8) (IL8-GelMA), was prepared via electrostatic spinning technology. Compared with Gelatin fiber, GelMA fiber possessed a smooth morphology with nanoscale diameter and better physical properties including hydrophilicity, elastic modulus, swelling rate and degradation rate. In addition, IL8-GelMA fiber membranes could lead an osteogenic differentiation of BMSCs. Moreover, the results of chemotaxis experiment demonstrated that both IL8 and IL8-GelMA fiber membranes promote the migration of BMSCs in vitro. These results suggested that IL8-GelMA fiber membranes can be used for cell-free scaffold of bone repair, which can not only recruit endogenous BMSCs, but also promote osteogenic differentiation of BMSCs.

We propose the meshfree-based physics-informed neural networks for solving the unsteady Oseen equations. Firstly, based on the ideas of meshfree and small sample learning, we only randomly select a small number of spatiotemporal points to train the neural network instead of forming a mesh. Specifically, we optimize the neural network by minimizing the loss function to satisfy the differential operators, initial condition and boundary condition. Then, we prove the convergence of the loss function and the convergence of the neural network. In addition, the feasibility and effectiveness of the method are verified by the results of numerical experiments, and the theoretical derivation is verified by the relative error between the neural network solution and the analytical solution.

Taking the fiber ring of the core device of the fiber optic gyro as the research object, the temperature field simulation analysis of the fiber gyroscope was carried out by ANSYS finite element analysis software, and the structural optimization of the fiber gyroscope was carried out, which effectively improved the temperature field distribution uniformity of the fiber optic ring and reduced the overall thermal equilibrium temperature and time when the fiber gyro reached stability.

Manipulation of the valley degree of freedom provides a new path for quantum information technology, but the real intrinsic large valley-polarization materials are rarely reported up to date. Here, we perform first-principles calculations to predict a class of 2H-phase single layer (SL) materials LuX 2 (X = Cl, Br, I) to be ideal candidates. SL-LuX 2 are ferrovalley materials with a giant valley-polarization of 55 meV–148 meV as a result of its large spin–orbital coupling (SOC) and intrinsic ferromagnetism (FM). The magnetic transition temperatures of SL-LuI2 and SL-LuCl2 are estimated to be 89 K–124 K, with a sizable magnetic anisotropy at out-of-plane direction. Remarkably, the anomalous valley Hall effect (AVHE) can be controlled in SL-LuX 2 when an external electric field is applied. Moreover, the intrinsic valley-polarization of SL-LuI2 is highly robust for biaxial strain. These findings provide a promising ferrovalley material system for the experimentation of valleytronics and subsequent applications.

The application of a sodium laser guide star is the key difference between a modern adaptive optics system and traditional adaptive optics system. Especially in system such as multiconjugate adaptive optics, a sodium laser guide star asterism that is formed by several laser guide stars in a certain pattern is required to probe more atmospheric turbulence in different directions. To achieve this, a sodium laser guide star asterism launching platform is required. In this paper, we introduce the sodium laser guide star asterism launching platform built and tested on the 1.8 m telescope of Gaomeigu Observatory. The platform has two functions: one function is to compare the performance of sodium laser guide stars generated by different lasers at the same place, and the other function is to generate a sodium laser guide star asterism with an adjustable shape. The field test results at the beginning of 2021 verified the important role of the platform, which is also the first time that a sodium laser guide star asterism was realized in China.

The quantum anomalous Hall effect (QAHE) has special quantum properties that are ideal for possible future spintronic devices. However, the experimental realization is rather challenging due to its low Curie temperature and small non-trivial bandgap in two-dimensional (2D) materials. In this paper, we demonstrate through first-principles calculations that monolayer Co2Te material is a promising 2D candidate to realize QAHE in practice. Excitingly, through Monte Carlo simulations, it is found that the Curie temperature of single-layer Co2Te can reach 573 K. The band crossing at the Fermi level in monolayer Co2Te is opened when spin–orbit coupling is considered, which leads to QAHE with a sizable bandgap of E g = 96 meV, characterized by the non-zero Chern number (C = 1) and a chiral edge state. Therefore, our findings not only enrich the study of quantum anomalous Hall effect, but also broaden the horizons of the spintronics and topological nanoelectronics applications.

The MMC converter valve adopts the water-cooled heat dissipation method. The automatic exhaust valve is installed at the upper part of the main water pipe, and the manual ball valve is installed between the automatic exhaust valve and the main water pipe, which is made of insulating material. During laboratory tests, it was found that the switch state of the manual ball valve may lead to an abnormal discharge of the manual ball valve. When the manual ball valve is closed, it is filled with air, and the insulating material bears high voltage, and the air inside will be broken down. This paper studies the abnormal discharge phenomenon of the manual ball valve, analyses the discharging principle, evaluates the influence on converter valve equipment, and proposes an optimal design scheme.

In this paper, models of hot carrier degradation (HCD) in nMOSFET and nFinFET, combined with the physical mechanism and reaction-diffusion framework and considering saturation effect, are proposed. The HCD data of different technology nodes of nMOSFET and nFinFET are used to verify the accuracy of the models. The results show that the prediction errors of device parameter degradation under different stress voltages are less than 10% for several types of short channel devices, which is better than the existing reported research results. Furthermore, the models have simple analytical expressions that allow them to not only be applied to device HCD prediction, but also be extended to circuit level HCD prediction tool more easily.

Based on the principle of electron cyclotron maser (ECM), gyrotrons are among the most promising devices to generate powerful coherent terahertz (THz) radiation and play a vital role in numerous advanced THz applications. Unfortunately, THz ECM systems using a conventional high-Q cavity were theoretically and experimentally demonstrated to suffer from strong ohmic losses, and, accordingly, the wave output efficiency was significantly reduced. A scheme to alleviate such a challenging problem is systematically investigated in this paper. The traveling-wave operation concept is employed in a 1-THz third harmonic gyrotron oscillator, which strengthens electron-wave interaction efficiency and reduces the ohmic dissipation, simultaneously. A lossy belt is added in the interaction circuit to stably constitute the traveling-wave interaction, and a down-tapered magnetic field is employed to further amplify the forward-wave (FW) component. The results demonstrate that the proportion of ohmic losses is nearly halved, and output efficiency is nearly doubled, which is promising for further advancement of high-power continuous-wave operation of the ECM-based devices.

Magnetic thin films are essential building blocks for spintronic devices. Whether the spin-dependent properties associated with a parental bulk can be preserved at the surface or interface with a lowered symmetry represents an important topic to be addressed. In the work, theoretical calculations are performed to study the structural, electronic and magnetic properties of the bulk CoRhCrAl quaternary Heusler alloy and its (111)-, (001)- and (110)-oriented thin films by using the VASP package based on the first-principles density functional theory. Our results indicate that the bulk structure of CoRhCrAl alloy is half-metallic (HM) in character with 100% spin-polarization, and its spin-down bandgap and total magnetic moment are E g ↓ = 0.3 0 eV and 3.00 μ B, respectively. For the thin film structures with different orientations and terminations, half-metallicity only exists in the (111)-oriented thin film with Al-termination, but is lost in the Co-, Rh- or Cr-terminations. On the other hand, both the (001)- and (110)-oriented thin films are partially or nearly HM. Interestingly, the half-metallicity is lost on introducing U parameter in the calculations.

The synergistic influences of boron, oxygen, and titanium on growing large single-crystal diamonds are studied using different concentrations of B2O3 in a solvent–carbon system under 5.5 GPa–5.7 GPa and 1300 °C–1500 °C. It is found that the boron atoms are difficult to enter into the crystal when boron and oxygen impurities are doped using B2O3 without the addition of Ti atoms. However, high boron content is achieved in the doped diamonds that were synthesized with the addition of Ti. Additionally, boron–oxygen complexes are found on the surface of the crystal, and oxygen-related impurities appear in the crystal interior when Ti atoms are added into the FeNi–C system. The results show that the introduction of Ti atoms into the synthesis cavity can effectively control the number of boron atoms and the number of oxygen atoms in the crystal. This has important scientific significance not only for understanding the synergistic influence of boron, oxygen, and titanium atoms on the growth of diamond in the earth, but also for preparing the high-concentration boron or oxygen containing semiconductor diamond technologies.

In order to address the problem of inconsistent sampling frequency and accuracy of each sensor in multi-sensor data fusion technology, the algorithm of Gaussian Process Regression (GPR) is proposed for time alignment, and in the scenario where the target motion model is uniform linear motion and uniform turning motion, the simulation is compared and analyzed respectively. The simulation results show that the proposed algorithm can effectively improve the accuracy of time synchronization.

Microwave ablation (MWA) is a cancer treatment method. The tumor tissue absorbs electromagnetic energy, which heats and kills it. A microwave ablation antenna plays a critical role in this process. Its radiation field must completely cover the tumor but not the healthy tissue. At present, the radiation pattern of most invasive ablation antennas is spherical. However, in the clinic, the shape of some tumors may be asymmetrical or the antenna cannot be inserted into the center of the tumor for some other reason. In order to solve these problems, a directional heating antenna for microwave ablation is proposed in this paper. The proposed antenna, operating at 2.45 GHz, consists of a monopole and a reflector. The feed is given by a substrate integrated coaxial line (SICL) and coplanar waveguide (CPW). The omnidirectional radiation field of the monopole is reflected by a reflector that is extended from the outer conductors of the SICL to form a directional radiation field. The impedance matching network is designed on SICL to match the antenna to 50 Ω. The antenna is fabricated using a mature printed circuit board (PCB). The reflection coefficient of the antenna in porcine liver tissue measured by a vector network analyzer shows good agreement with the simulations. Then, an ablation experiment in porcine liver is conducted with power of 10 W for 10 min, and the experimental results confirm the validity of the design.

Self-walking platform is used to support subway tunnel maintenance and construction. However, the kinematics model and motion control of the subway tunnel self-propelled platform are different from that of the plane, it is a non-holonomic constrained system with serious sliding, strong coupling and highly nonlinear, and the pipeline environment is complex, so it is difficult to accurately model. In order to solve these differences, the kinematic characteristics of wheels in cylindrical workspace are discussed first. The geometric constraints of self-walking platform in circular tunnels are also analyzed. Secondly, considering the complexities of self-walking platform motion model, a control algorithm based on fuzzy logic is proposed. Finally, through MATLAB and ADAMS joint simulation, the scenarios for virtual platform moving in circular tunnels are simulated, which shows the effectiveness of the algorithm.

The two-dimensional (2D) materials with nodal line band crossing have been attracting great research interest. However, it remains a challenge to find high-stable nodal line structure in 2D systems. Herein, based on the first-principles calculations and theoretical analysis, we propose that monolayer B6O possesses symmetry protected Dirac nodal line (DNL) state, with its Fermi velocity of 106 m/s in the same order of magnitude as that of graphene. The origin of DNL fermions is induced by coexistence of time-reversal symmetry and inversion symmetry. A two-band tight-binding model is further given to understand the mechanism of DNL. Considering its robustness against spin–orbit coupling (SOC) and high structural stability, these results suggest monolayer B6O as a new platform for realizing future high-speed low-dissipation devices.

Three most common methods for preparing PEDOT (poly(3,4-ethylenedioxythiophene)) are studied, including vapor phase polymerization (VPP), in-situ dipping (ISD) and solution deposition (SD) techniques. The PEDOT coated nonwoven fabric (PEDOT@NWF) composites were successfully fabricated via these three processes and have been proven to be conductive and equipped with piezoresistive properties. For each preparation method, factors that may affect product properties, such as concentrations of reagents, reaction temperature, reaction time, etc were explored to summarize the optimal parameters. The PEDOT@NWF composites prepared via different fabrication techniques were analyzed and compared through a series of tests and characterizations. The sensing performance of as-prepared pressure sensors are also been studied. The experimental results demonstrate that PEDOT@NWF prepared by VPP method (PEDOT@NWF-VPP) has the fastest response time (80 ms) and recovery time (40 ms), the composite prepared by ISD method (PEDOT@NWF-ISD) has the highest sensitivity for the pressure range less than 5 kPa (21.162 kPa−1) and long-term cycle stability (over 5000 cycles). Sensor utilized PEDOT@NWF-ISD as the piezoresistive layer was assembled and used to detect small pressure such as voice vibrations and air flow, implying that this designed pressure sensor has promising potential in the application of wearable electronic devices and healthcare monitors.

A cold preamplifier based on superconducting quantum interference devices (SQUIDs) is currently the preferred readout technology for the low-noise transition edge sensor (TES). In this work, we have designed and fabricated a series SQUID array (SSA) amplifier for the TES detector readout circuit. In this SSA amplifier, each SQUID cell is composed of a first-order gradiometer formed using two equally large square washers, and an on-chip low pass filter (LPF) as a radio-frequency (RF) choke has been developed to reduce the Josephson oscillation interference between individual SQUID cells. In addition, a highly symmetric layout has been designed carefully to provide a fully consistent embedded electromagnetic environment and achieve coherent flux operation. The measured results show smooth V–Φ characteristics and a swing voltage that increases linearly with increasing SQUID cell number N. A white flux noise level as low as 0.28 μ Φ 0/Hz1/2 is achieved at 0.1 K, corresponding to a low current noise level of 7 pA/Hz1/2. We analyze the measured noise contribution at mK-scale temperatures and find that the dominant noise derives from a combination of the SSA intrinsic noise and the equivalent current noise of the room temperature electronics.

For photon detection, superconducting transition-edge sensor (TES) micro-calorimeters are excellent energy-resolving devices. In this study, we report our recent work in developing Ti-/Au-based TES. The Ti/Au TES devices were designed and implemented with a thickness ratio of 1:1 and different suspended structures using micromachining technology. The characteristics were evaluated and analyzed, including surface morphology, 3D deformation of suspended Ti/Au TES device structure, I–V characteristics, and low-temperature superconductivity. The results showed that the surface of Ti/Au has good homogeneity and the surface roughness of Ti/Au is significantly increased compared with the substrate. The structure of Ti/Au bilayer film significantly affects the deformation of suspended devices, but the deformation does not affect the I–V characteristics of the devices. For devices with the Ti/Au bilayer (150 – m × 150 μm) and beams (100 μ m × 25 μm), the transition temperature (T c) is 253 mK with a width of 6 mK, and the value of the temperature sensitivity α is 95.1.

With the continuous development of society and economy, the development and application of mobile communications have become more and more popular, and more people have begun to use mobile devices for office, study and life. The quality of mobile communications network signals directly affects people’s experience of use. The scope of actual application has gradually increased with the renewal of the technology itself. Based on the random walk model, this paper constructs a mobile communication data optimization plan. Through data storage, transmission delay, and information total control, the optimization form of wireless network mobile communication data transmission performance is studied. Practice shows that this scheme can effectively improve communication quality and transmission efficiency.

Gamma-ray bursts (GRBs) are brief, intense, gamma-ray flashes in the universe, lasting from a few milliseconds to a few thousand seconds. For short gamma-ray bursts (sGRBs) with duration less than 2 seconds, the isotropic energy (E iso) function may be more scientifically meaningful and accurately measured than the luminosity (L p) function. In this work we construct, for the first time, the isotropic energy function of sGRBs and estimate their formation rate. First, we derive the L p – E p correlation using 22 sGRBs with known redshifts and well-measured spectra and estimate the pseduo redshifts of 334 Fermi sGRBs. Then, we adopt the Lynden-Bell c − method to study isotropic energy functions and formation rate of sGRBs without any assumption. A strong evolution of isotropic energy E iso ∝ (1+z)5.79 is found, which is comparable to that between L p and z. After removing effect of the cosmic evolution, the isotropic energy function can be reasonably fitted by a broken power law, which is ϕ ( E iso , 0 ) ∝ E iso , 0 − 0.45 for dim sGRBs and ϕ ( E iso , 0 ) ∝ E iso , 0 − 1.11 for bright sGRBs, with the break energy 4.92 × 1049 erg. We obtain the local formation rate of sGRBs is about 17.43 events Gpc−3 yr−1. If assuming a beaming angle is 6° to 26°, the local formation rate including off-axis sGRBs is estimated as ρ 0,all = 155.79 – 3202.35 events Gpc−3 yr−1.

Optical superconducting transition-edge sensor (TES) has been widely used in quantum information, biological imaging, and fluorescence microscopy owing to its high quantum efficiency, low dark count, and photon number resolving capability. The temperature sensitivity (αI ) and current sensitivity (βI ) are important parameters for optical TESs, which are generally extracted from the complex impedance. Here we present a method to extract αI and βI based on a two-fluid model and compare the calculated current–voltage curves, pulse response, and theoretical energy resolution with the measured ones. This method shows qualitative agreement that is suitable for further optimization of optical TESs.