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Gearboxes are one of the most critical transmission devices in wind turbines (WTs). Order tracking (OT) of variable-speed WT gear is a powerful means to carry out fault diagnosis. Since it is difficult to install a tachometer or encoder for gearboxes with limited structural space, it is impossible to obtain the instantaneous angular speed (IAS) of the gearbox. In recent years, many tacholess techniques have been presented to estimate instantaneous phase from vibration signals for OT. However, their performance needs to be further improved to get a more exact diagnosis result. To solve this issue, this paper presents an enhanced IAS estimation approach for WT tacholess order tracking (TLOT), which is available for accurate IAS estimation of the rotating shaft, so that TLOT can be more effectively conducted under conditions of large speed variation and background noise. An improved cost function algorithm is designed to extract the IAS from the vibration signal. A Vold–Kalman filter and Hilbert transform are combined to calculate the instantaneous phase. Afterwards, the raw non-stationary vibration signal is resampled at an equal angle increment, and the envelope order spectrum is calculated from the resampled signal for fault diagnosis of the WT gearbox. The main innovating idea of this approach is to improve the traditional cost function ridge-extraction method by introducing gradient information based on probability and multi-harmonic time–frequency realignment, which makes the IAS estimation process more accurate and overcomes the limitations of traditional IAS estimation techniques. The effectiveness of the presented approach is demonstrated by using a vibration signal measured from real-world WT gearboxes, and the validation results demonstrate that the presented approach surpasses some state-of-the-art methods in IAS estimation accuracy and efficiency.

To accurately count densely stacked rebars belongs to semantic segmentation in image. Various methods have been proposed to segment the objects in single image. However, widely and densely stacking scene such as warehouse or vehicle stacking of rebars is always faced. For these scenes, clear image of end faces of rebars cannot be obtained through a single camera. Generally, multiple cameras are often used to take clear images to count rebars. One strategy is to stitch multiple images into a single image at pixel level first, and then count rebars in this stitched image. Various methods have been proposed to stitch images, but it is extremely difficult to stitch two images at pixel level accurately for parallax distortion or partially hidden. A topological stitching strategy is proposed in this paper to count the rebars in whole scene. In the method, rebars in each image are identified and counted first, and then the identification and counting results in the adjacent images are stitched so as to esitmate the total number of rebars. The perfomance of the method is evaluated on real datasets, and the counting accuracy exceeds 99%. Experiments show that the proposed method is effective on widely and densely stacked rebars identification.

In this paper, coupled-phase oscillator chains with localized many-body interactions are studied. Systems have rich patterns such as chimera and twisted states. The coupled-phase oscillator chains have long-range two-body interactions and short-range three-body interactions, which respectively play the role of long-range inhibition of short-range activation, just like inhibitors and activators in traditional reaction-diffusion systems. The role of many-body interaction in the system is studied through the Turing pattern diagram and the critical point of Turing instability is obtained. After Turing instability occurs, the system will flow to twisted states and chimera states. The study indicates that long-range inhibition and short-range activation give an explanation for the formation of such coherent-incoherent modes such as chimera states, and that many-body interactions are good candidates as activators of the system.

The layered pavements usually exhibit complicated mechanical properties with the effect of complex material properties under external environment. In some cases, such as launching missiles or rockets, layered pavements are required to bear large impulse load. However, traditional methods cannot non-destructively and quickly detect the internal structural of pavements. Thus, accurate and fast prediction of the mechanical properties of layered pavements is of great importance and necessity. In recent years, machine learning has shown great superiority in solving nonlinear problems. In this work, we present a method of predicting the maximum deflection and damage factor of layered pavements under instantaneous large impact based on random forest regression with the deflection basin parameters obtained from falling weight deflection testing. The regression coefficient R 2 of testing datasets are above 0.94 in the process of predicting the elastic moduli of structural layers and mechanical responses, which indicates that the prediction results have great consistency with finite element simulation results. This paper provides a novel method for fast and accurate prediction of pavement mechanical responses under instantaneous large impact load using partial structural parameters of pavements, and has application potential in non-destructive evaluation of pavement structure.

The passive radiative cooling technology shows a great potential application on reducing the enormous global energy consumption. The multilayer metamaterials could enhance the radiative cooling performance. However, it is a challenge to design the radiative cooler. In this work, based on the particle swarm optimization (PSO) evolutionary algorithm, we develop an intelligent workflow in designing photonic radiative cooling metamaterials. Specifically, we design two 10-layer SiO2 radiative coolers doped by cylindrical MgF2 or air impurities, possessing high emissivity within the selective (8–13 μm) and broadband (8–25 μm) atmospheric transparency windows, respectively. Our two kinds of coolers demonstrate power density as high as 119 W/m2 and 132 W/m2 at the room temperature (300 K). Our scheme does not rely on the usage of special materials, forming high-performing metamaterials with conventional poor-performing components. This significant improvement of the emission spectra proves the effectiveness of our inverse design algorithm in boosting the discovery of high-performing functional metamaterials.

Insulator contamination monitoring is an important way to avoid insulator contamination and maintain insulation performance. In order to ensure power supply and achieve contactless detection of insulator contamination status, a method is proposed in this paper to identify insulator contamination status by adopting infrared, ultraviolet, and visible multi-spectral image information fusion. An insulator with different contamination states in a number of substations is taken as the research object in this paper. The image segmentation is performed by using the seed region growth method to extract the infrared, ultraviolet and visible features of the insulator surface, and the radial basis function neural network learning algorithm is used to classify and decompose and fuse the images according to their different local area energies. The comparison of the recognition rates using infrared and ultraviolet features with those fused shows that the method has significant advantages and provides a new method for the detection of insulator contamination status.

Apple is an important horticultural crop in China and its production consumes large amounts of Chemical fertilizers. In a survey of more than 300 Chinese apple growers, we found that small farmers’ fertilizer inputs are blind. Current research lacks a comprehensive evaluation of fertilizer inputs and soil nutrient status for apple production in China, but the evaluation work will play a supporting role in the macro management decision of nutrient resources. In this study, a database of fertilizer inputs and soil nutrients in five major apple producing areas in China was constructed by means of data integration. Two main conclusions can be drawn from the analysis of the database. Firstly, the chemical N and P fertilizer inputs exceed the recommended use in all five production areas, and secondly, the organic matter content of orchard soils in the five production areas only reaches a maximum of level 3. The research shows that China’s agricultural authorities should carry out macro management of nutrient resources in apple orchards, so as to guide different producing areas to adjust fertilizer input according to their soil environment, so as to improve the utilization rate of fertilizer.

LES is used in the present work to simulate and unfold unsteady flow dynamics and mixing characteristics in a cavity-based supersonic combustor at low Mach numbers. In the combustor, a transverse jet is injected ahead of the cavity. Two inflow Mach numbers (Ma=1.2 and Ma=2.5) are numerically investigated. Fine instantaneous and average mixing flow structures are well identified and analyzed by LES. The mixing performance is also studied and compared. The simulation results show that penetration is dominated by jet/freestream momentum flux ratio, even though the inflow Mach number varies. It is also demonstrated that for a jet at low Mach inflow, a higher coefficient of pressure is attained. While around the jet location, a much higher peak of the mixing vorticity efficiency is obtained for low Mach inflow, which is of fundamental importance to the near-field mixing.

With the continuous development of China’s general aviation industry, there are urgent requirements for research on aircraft crashworthiness to provide better safety for aircraft occupants. According to the results of long-term crash investigations, if crash safety design is taken into account at the earliest stages of aircraft design, most accidents will become viable or partially survivable, which can greatly improve the survival rate of aircraft passengers after an accident. In this paper, the design criteria and design methods for crash resistance technology of aircraft cargo uphold pillars are studied, and the crash simulation analysis of a certain type of aircraft is analyzed. First, a feasible design method and optimization principle are formulated according to the specific characteristics of a certain type of aircraft; Then, the crash resistance characteristics of a certain type of aircraft are analyzed, and the finite element model of the fuselage and cargo uphold pillars structure is established based on the three-dimensional electronic prototype of the aircraft. By the crash conditions specified in the relevant specifications, a mechanical simulation study of the aircraft is carried out, and the results are analyzed. Finally, constructive comments are given based on the simulation results. The reliability of the design is verified using simulation analysis, which provides a reference for the simulation and analysis of the anti-crash design of the aircraft cargo uphold pillars structure.

According to relevant statistics, an aircraft will encounter lightning every 3000 hours on average. According to relevant research, the vast majority of aircraft encounter lightning during falling or climbing. For lightning protection of composite radome, there are usually measures such as metallization treatment on the surface, the layout of lightning protection diversion strips, etc., to avoid lightning on the radome by guiding the flash current.

The full-fruit period in apple orchards has the greatest environmental impact during the whole apple life cycle, and the characteristics of apple planting and high investment in agricultural materials in China aggravate the impact of this stage on the environment. The life cycle assessment (LCA) method was used to study the resource use (RU), global warming potential (GWP), environmental acidification potential (AP), and eutrophication potential (EP) of apple orchards in the full-fruit period. These apple orchards are, smallholder orchards (SO) in the Bohai Bay area (BH), commercial orchards (CO) in the Bohai Bay area, smallholder orchards in the Loess Plateau area (LP), and commercial orchards in the Loess Plateau area. The results showed that the RU of commercial orchards was 23.87% higher than that of smallholder orchards, the EP of smallholder orchards was 72.36% higher than that of commercial orchards, the RU of the Bohai Bay was 19.70% higher than that of the Loess Plateau, the EP in the Loess Plateau was 35.93% higher than that in Bohai Bay.

The strapdown magnetic vector measurement system, which can measure the magnetic vector and the attitude of a magnetometer simultaneously, has wide applications in geophysical prospecting, etc. Calibration of systematic errors, including magnetometer errors and misalignment errors, is essential for this system. Traditional methods calibrate these two errors separately, with the problem of cumbersome steps and being dependent on special data acquisition methods, such as rotation. An original method that combines a plane compression method with an ellipsoid fitting method is proposed in this paper, which can simultaneously complete the calibration calculation of magnetometer error and misalignment error in one experiment. The calculation can be performed using the spatial scatter point data required by the traditional attitude-independent magnetometer calibration method, and no additional mechanical equipment is required. A mathematical analysis of this method is performed to study the elements decreasing the measurement accuracy of the system, and numerical simulation and field experiments are performed to validate the analysis. The results indicate that the method can contribute to the accuracy improvement of magnetic vector measurement systems.

In this paper, the engineering of pulse power supply in electromagnetic launch technology is studied in depth, the advantages and disadvantages of optical fiber communication transmission currently used are analyzed, and then the requirements for data transmission of pulse power supply system are summarized, and several commonly used wireless communication technologies are analyzed and compared, such as ZigBee, LoRa, SigFox, NB IoT, 5G, etc. According to the comprehensive comparison of these technologies in transmission distance, rate, bandwidth, security, time delay, self built network and other aspects, the scheme of using LoRa wireless communication technology to replace optical fiber transmission is finally determined, and the LoRa wireless communication network construction, controller hardware circuit design, module software program, data transmission communication protocol, data encryption, data storage and other contents in the scheme are further designed in detail, It also predicts the further research and development of LoRa wireless communication technology in pulse power supply.

The increasing data acquisition information in the distribution network brings new challenges to the monitoring and management of the distribution network. Therefore, this paper proposes a visual inspection system of a distribution network based on UAVs. The overall system hardware and UAV flight control power supply hardware are designed. The distance between the UAV and the obstacles is calculated by detecting the duration of laser signal reception. The visual inspection of the UAV obstacle avoidance power distribution network is carried out. The visible light, infrared, and laser data are fused, multi-source data are processed cooperatively, and the visual inspection information is collected and summarized. The test results show that the system has high efficiency and can provide accurate information for power system operators and managers in a relatively timely manner.

Treatment of operate room wounds infections is a clinically more challenging process. Therefore, several techniques and wound care materials have been taken to improve wound healing mechanisms. The present study is mainly focused on zinc oxide and fucoidan-loaded chitosan nanofiber scaffolds fabricated by the electrospinning method. The functional groups, morphology, and hydrothermal stability of fabricated Zn/Fu@Cs were observed and investigated by microscopic and some spectroscopic techniques. The wound healing potential of Zn/Fu@Cs nanofiber has been evaluated by various in vitro biological experiments. In addition, the prepared nanofiber showed suitable bacterial growth inhibition against P. aeruginosa, B. subtilis, S. aureus, and E. coli wound infecting bacteria and in vitro studies confirmed the excellent cell proliferation, and cytocompatibility. In vitro study exhibited significant cell proliferation and viability is observed in Zn/Fu@Cs nanofiber treated L929 cells within 3 days, which is comparable to the control it is higher. In wound scratch assay the wound healing efficiency has been monitored on the human skin fibroblast L929 cell line. The wound scratch experiment results revealed that the Zn/Fu@Cs nanofiber shows quick cell regeneration without bacterial infections. The biodegradation study concluded the biocompatibility of nanofibers under physiological condition. The overall results suggest that the Zn/Fu@Cs nanofiber is a potential material for wound care with enhanced antibacterial property against operate room pathogens.

Eye movement servo control has the advantage of non-contact and the eye movement is not affected by other limbs. By applying eye-tracking technology to rehabilitation research of people with movement disorders, the interaction between eye-tracking technology and computers will be gradually put into practice, which is equivalent to giving patients a pair of “invisible hands” that can give instructions freely. In this paper, a servo control method based on eye-movement coding technology is proposed to solve the problems of low accuracy, poor reliability, and insufficient human intention initiative in the field of eye-movement servo control of human-computer visual interaction. The human eye movement instruction is processed by coding and integrated with human eye movement intention to realize intelligent servo control of human eye intention. In order to improve the accuracy of eye movement servo control, this paper proposes an eye movement instruction coding processing method, which uses the trained AdaBoost fusion strong classifier algorithm and the landmark detector to detect the real-time algorithm in the video sequence to complete the eye location and blink determination. In this paper, an improved pupil location method based on multi-angle joint detection is proposed. The pupil location is completed by using the information of eye image points, and the digital coding model of eye command action is constructed, which provides an instruction base for eye movement servo control. In order to improve the reliability and initiative of eye-movement servo control, a reinforcement learning method combining eye-movement coded instruction and intention was proposed. By integrating the improved DDPG continuous control strategy reinforcement learning algorithm with eye movement intention instruction, the environmental status can be sensed in the human-computer interaction process and the optimal strategy of eye movement instruction selection can be learned.

The working environment of the pipeline system of the launch vehicle is very complex. Bellows in piping system should endure high temperature, corrosive medium, vibration and other conditions, which require for high reliability. However, due to the restrictions of fixed location, weight reduce requirement, the number and location of bellows are strictly required. There is a great difference for the bellows design method between the launch vehicle and the ground pipeline. In this paper, a bellows designing method for launch vehicle is introduced in detail. The method calculates the compensation amount of bellows under divided working conditions, and checks the fatigue damage coefficient as the main failure judgement basis. It has been proved by practice that the designing method of divided working conditions can solve the design problems of the bellows of launch vehicles effectively.

Nickel-based microparts possess a short lifetime owing to their rapid dissolution in corrosive environments. To mitigate this phenomenon, composite microparts of graphene/Ni were prepared using UV-LIGA technology; their corrosion behavior was examined in acid, alkali, and salt solutions as well as after subjecting them to heat-treatment processes. The microstructures were investigated with scanning electron microscopy (SEM), x-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Corrosion resistances were characterized through various electrochemical tests and compared with those of pure Ni microparts. The results demonstrate that the surface oxidation layer (i.e.,the protective layer) of the microparts was readily destroyed in NaCl and H2SO4 solutions without the formation of a passivation film; however, a passivation film was formed in the NaOH solution. The corrosion rates of graphene/Ni in NaCl, NaOH, and H2SO4 corrosion solutions were reduced by 73%, 22%, and 84%, respectively, relative to those of pure Ni microparts. This can be primarily attributed to the homogeneous dispersion of graphene in the Ni matrix, which refined the grain size, and the impermeability and chemical stability of graphene, which lengthened the diffusion path of the corrosive medium. In addition, heat treatment of the graphene/Ni microparts at 200 °C increased the corrosion resistance by a factor of nearly one with little change in microhardness, which can be attributed to the removal of internal stress and the increased proportion of CSL grain boundares. Corrosion occurred at the interface between nickel and graphene, lengthening the corrosion path.

Shear-coupled grain boundary (GB) migration is of importance theoretically on the mechanisms of GB behaviors and application oriented on the development of novel processing methods by plastic deformation. We demonstrate via molecular dynamics simulations that the interstitial species carbon may affect the shear-coupled migration in α-iron strongly. The impact of carbon selectively takes effect depending on the variety of grain boundaries. Specifically, the coupling factor of the Σ9(221) GB is increased in the presence of carbon. While the carbon effect is inactive for the Σ17(223) GB. The influence of carbon is revealed to be connected with the disconnection modes of grain boundaries. The results of the work implicate correlations between the carbon enrichment and the final microstructure after severe plastic deformation.

Objective. Retinal prostheses aim at restoring sight in patients with retinal degeneration by electrically stimulating the inner retinal neurons. Clinical trials with patients blinded by atrophic age-related macular degeneration using the PRIMA subretinal implant, a 2 × 2 mm array of 100 µm-wide photovoltaic pixels, have demonstrated a prosthetic visual acuity closely matching the pixel size. Further improvement in resolution requires smaller pixels, which, with the current bipolar design, necessitates more intense stimulation. Approach. We examine the lower limit of the pixel size for PRIMA implants by modeling the electric field, leveraging the clinical benchmarks, and using animal data to assess the stimulation strength and contrast of various patterns. Visually evoked potentials measured in Royal College of Surgeons rats with photovoltaic implants composed of 100 µm and 75 µm pixels were compared to clinical thresholds with 100 µm pixels. Electrical stimulation model calibrated by the clinical and rodent data was used to predict the performance of the implant with smaller pixels. Main results. PRIMA implants with 75 µm bipolar pixels under the maximum safe near-infrared (880 nm) illumination of 8 mW mm−2 with 30% duty cycle (10 ms pulses at 30 Hz) should provide a similar perceptual brightness as with 100 µm pixels under 3 mW mm−2 irradiance, used in the current clinical trials. Contrast of the Landolt C pattern scaled down to 75 µm pixels is also similar under such illumination to that with 100 µm pixels, increasing the maximum acuity from 20/420 to 20/315. Significance. Computational modeling defines the minimum pixel size of the PRIMA implants as 75 µm. Increasing the implant width from 2 to 3 mm and reducing the pixel size from 100 to 75 µm will nearly quadrupole the number of pixels, which should be very beneficial for patients. Smaller pixels of the same bipolar flat geometry would require excessively intense illumination, and therefore a different pixel design should be considered for further improvement in resolution.

Objective. Mixing/dissociation of sleep stages in narcolepsy adds to the difficulty in automatic sleep staging. Moreover, automatic analytical studies for narcolepsy and multiple sleep latency test (MSLT) have only done automatic sleep staging without leveraging the sleep stage profile for further patient identification. This study aims to establish an automatic narcolepsy detection method for MSLT. Approach. We construct a two-phase model on MSLT recordings, where ambiguous sleep staging and sleep transition dynamics make joint efforts to address this issue. In phase 1, we extract representative features from electroencephalogram (EEG) and electrooculogram (EOG) signals. Then, the features are input to an EasyEnsemble classifier for automatic sleep staging. In phase 2, we investigate sleep transition dynamics, including sleep stage transitions and sleep stages, and output likelihood of narcolepsy by virtue of principal component analysis (PCA) and a logistic regression classifier. To demonstrate the proposed framework in clinical application, we conduct experiments on 24 participants from the Children’s Hospital of Fudan University, considering ten patients with narcolepsy and fourteen patients with MSLT negative. Main results. Applying the two-phase leave-one-subject-out testing scheme, the model reaches an accuracy, sensitivity, and specificity of 87.5%, 80.0%, and 92.9% for narcolepsy detection. Influenced by disease pathology, accuracy of automatic sleep staging in narcolepsy appears to decrease compared to that in the non-narcoleptic population. Significance. This method can automatically and efficiently distinguish patients with narcolepsy based on MSLT. It probes into the amalgamation of automatic sleep staging and sleep transition dynamics for narcolepsy detection, which would assist clinic and neuroelectrophysiology specialists in visual interpretation and diagnosis.

According to the motion characteristics of Axial-Symmetric Vectoring Exhaust Nozzle (AVEN), its motion process is divided into the convergence deflection of the adjusting piece of the A8 sub-mechanism and the expansion deflection of the adjusting piece of the A9 sub-mechanism. Taking the A9 sub-mechanism as an example, proposing a method based on Solidworks-Abaqus-Adams multi-software platform to establish a rigid-flexible coupled parametric model and run the motion simulation model to analyze the influence of different factors on the motion accuracy of the mechanism. Basing on the Monte Carlo sampling algorithm to design a program of automatic sampling solution that is separated from Adams platform. Under the condition of meeting certain accuracy requirements, the degree of automation in the sampling process is greatly improved. Finally, the probability distribution of the performance parameters of the A9 mechanism is obtained, and its reliability is calculated. The research results show that when considering various influencing factors, the motion accuracy of the mechanism will have corresponding deviations, which will have a certain impact on the reliability of the mechanism.

A reconfigurable absorber/reflector, which has optical transparency and broadband switching function, is developed based on structured water medium. The conductive indium tin oxide coating is deposited on a thin polyethylene terephthalate film to act as the reflective backplane. Pure water is encapsulated by polydimethylsiloxane materials to construct structured water. The average optical transmittance is about 61.88%/56.44% in the visible spectrum of 380–760 nm with/without pure water. Based on the combination of the stacking technique and the super-element configuration, an obvious switching function from broadband absorption (12.47–28.43 GHz) to broadband reflection (12–30 GHz) can be attained under normal incidence through the injection and discharge of pure water. Besides, the broadband switchable characteristics of the proposed structure remain effective for transverse electric (TE) and transverse magnetic (TM) modes when illuminated by oblique incident waves up to 45°. Moreover, the proposed switchable absorber/reflector shows good temperature stability and can work under different liquid temperatures. Furthermore, the excellent performance of the proposed design is demonstrated by both simulated and experimental results, exhibiting great potential as transparent smart windows in large-scale ground-based stealth systems.

This paper presents a precise circuit model for predicting the shielding effectiveness (SE) and resonances of the cylindrical enclosure. In this model, the waveguide theory is combined with the Robinson model to deal with the influence of the high-order modes and the arbitrary position. The transmission line theory is applied to calculate the enclosure equipped with symmetric apertures or a dielectric layer. The results show that the proposed model can accurately calculate the orthogonal components of voltage response and predict the SE of the monitor point over a wide frequency range. Compared with traditional numerical methods, the proposed model costs less computing time and resources to operate because of employing analytical formulations. The effectiveness of this model is verified by the three-dimensional full-wave transmission line method.

As the core component of the adaptive optics system, the deformable mirror is developing towards miniaturization and integration through the combination of MEMS technology. In this paper, based on the inverse piezoelectric effect of piezoelectric materials, a piezoelectrically driven deformable reflective micromirror is designed and fabricated by physical vapor deposition, UV lithography, eutectic bonding, mechanical cutting, deep reactive ion etching (RIE) and other processes to complete the preparation of micromirrors. The problems related to the eutectic bonding process of PZT and Si in the fabrication of micromirrors are emphatically studied through tensile experiments. The micromirror was tested with a laser interferometer. The test results showed that the prepared micromirror could achieve a maximum deformation of 0.6 μm in the positive direction and 1.7 μm in the negative direction when a voltage of ±1.5 kV was applied.

A novel micro-thermal conductivity detector with a semi-diffusion gas channel is demonstrated. This semi-diffusion channel can reduce the flow-rate interference significantly by lowering the gas flow velocity above the hot film and maintains fast response speed at the same time. Simulations indicate that the semi-diffusion type with triangular shape has the best flow-insensitive effect. When the temperature of the hot film is about 500 K, the maximal temperature deviation of the hot film caused by flow rate change in this case can be decreased by 82.4% compared with the traditional straight type. Experiments are carried under the conditions of sample and carrier gas commonly used in gas chromatograph (GC), which is achieved by using He and CO2. With the sample gas flow ranging from 1 to 20 sccm, the voltage deviation in the semi-diffusion type is reduced for as much as 85.1% of that in the straight type. This effect is also verified in binary gases with various thermal conductivities. In addition, the recovery time of the semi-diffusion design is almost the same as the straight type, less than 170 ms, indicating it is suitable for the rapid gas detection in GC.

This study presents a novel acoustic metasurface with a coplanar series-type Helmholtz resonator with curled necks. Using extended necks that are embedded in cavities enables one to significantly reduce the resonance frequency of the resonator. The sound absorption performance of this metasurface is investigated theoretically, numerically, and experimentally. The absorption band can be easily adjusted by altering the neck length and diameter. To achieve a wide frequency band with high absorption, two inhomogeneous units are arranged in parallel. Theoretical and finite-element predictions exhibit good agreement with the experimental measurements. The results demonstrate that the proposed acoustic metasurface with subwavelength thickness is capable of effectively absorbing low-frequency sound.

Aiming at the scheduling optimization problem of the regional electrical integrated energy network under the background of the dual carbon target strategy, on the premise of ensuring the balance and stability of the IIES energy side supply, an optimization solution method for the regional electrical-gas integrated energy network scheduling considering carbon trading was proposed. Based on the priority model of building multi-energy equipment, and taking the minimum sum of the output cost of energy production, the cost of energy conversion, and the carbon transaction cost caused by net carbon emissions as the objective function, the daily optimal scheduling of the regional electrical integrated energy network was established. The model realized the optimal solution of the output value of different energy forms. Utilizing simulation technology, the objective function values of the unit carbon tax price of 8.32$/t, 24.79$/t, and 46.94$/t under the specific scenario of IIES were discussed. The scenario with the optimal objective function (unit carbon tax price of 24.79$/t) was further compared. In addition, the real-time output value of multi-energy equipment was analyzed when the network scheduling optimization was optimized.

As the scale of the Integrated Energy System network continues to expand and the coupling and conversion of multiple energy flows deepens, the system becomes more complex and vulnerable, which poses new challenges to the stability of the system structure and the safety of its operation. Identifying the key nodes of the Integrated Energy System is the key to improve the stability and security of the system. In order to comprehensively analyze the node attributes in the integrated energy network, complex network theory and unified energy flow theory are applied to the static topology and dynamic operation state analysis of the Integrated Energy System, and the key node identification method of the Integrated Energy System is proposed from the attributes of node location information, global information and the impact on nodes during operation. Finally, simulation experiments are conducted with a typical Integrated Energy System to verify the effectiveness and superiority of the identification method proposed in this paper.

Aiming at the problem that the renewable energy cannot be efficiently utilized and the energy consumption cost is high in the production process of the park with wind and solar energy, an integrated energy system (IES) for the park that takes into account the wind and solar energy consumption is proposed. Optimize the scheduling method. First, an output model of the park’s comprehensive energy system including wind-solar renewable energy was established, and biogas was used as the gas source. Then, considering a variety of energy constraints, and taking the lowest energy consumption cost and the highest wind and light absorption rate as the goal, the improved multi-objective particle swarm algorithm is used to optimize the solution. Finally, the proposed method is verified by taking an integrated energy system of a park as a practical example. The results show that the proposed optimal scheduling method can effectively reduce the daily operating cost of the park and improve the local consumption rate of renewable energy.

In this article, the bunched transport of photoexcited carriers in a GaAs photoconductive semiconductor switch (PCSS) with interdigitated electrodes is investigated under femtosecond laser excitation. Continuous outputs featuring high gain are obtained for single shots and at 1 kHz by varying the optical excitation energy. An ensemble three-valley Monte Carlo simulation is utilized to investigate the transient characteristics and the dynamic process of photoexcited carriers. It demonstrates that the presence of a plasma channel can be attributed to the bunching of high-density electron–hole pairs, which are transported in the form of a high-density filamentary current. The results provide a picture of the evolution of photoexcited carriers during transient switching. A photoinduced heat effect is analyzed, which reveals the related failure mechanism of GaAs PCSS at various repetition rates.

The development process of space Langmuir probe needs to complete a large number of tests and calibration tests on the ground. Due to the long calibration period, complexity and high cost of plasma environment calibration, calibration tests are usually carried out after the instrument has been developed, in order to conduct preliminary tests on Langmuir probe during the instrument development process to verify the performance, as well as to save the cost of calibration tests and increase the reliability of the instrument, An advanced spatial Langmuir probe volt-ampere(I-V) load simulator was designed in this paper. Based on the positive and negative polarity of the external bias voltage, the I-V characteristic curve of the Langmuir probe was divided into positive and negative characteristic curves, which were realized by the combination of the output characteristic curves of NPN and PNP transistors, and the diode switching selectivity. The laboratory test results were consistent with the theoretical curve, verifying the validity and compliance of the design, which can play an important role in supporting the development of the space Langmuir probe and the calibration of the plasma environment.

Rupturing the alumina shell (shell-breaking) is a prerequisite for releasing energy from aluminum powder. Thermal stress overload in a high-temperature environment is an important factor in the rupture of the alumina shell. COMSOL Multiphysics was used to simulate and analyze the shell-breaking response of micron-scale aluminum particles with different particle sizes at 650 °C in vacuum. The simulation results show that the thermal stability time and shell-breaking response time of 10 μm–100 μm aluminum particles are 0.15 μs–11.44 μs and 0.08 μs–3.94 μs, respectively. They also reveal the direct causes of shell breaking for aluminum particles with different particle sizes. When the particle size is less than 80 μm, the shell-breaking response is a direct result of compressive stress overload. When the particle size is between 80 μm and 100 μm, the shell-breaking response is a direct result of tensile stress overload. This article provides useful guidance for research into the energy release of aluminum powder.

The fine-grained customer load data provides a large amount of information for the analysis of customer’s electricity consumption behavior pattern. Therefore, this paper proposes an algorithm for identifying the electricity consumption patterns of electric power users based on k-means algorithm. Our method is verified on the electricity consumption data of Irish residents and Shanghai Southern Industrial and Commercial users. The experimental results show that our method can divide the curves with similar electricity consumption patterns efficiently.

With the continuous expansion of the power grid, the number of alarm information collected by the dispatching center is also increasing. How to filter out key information from massive alarm information, delete irrelevant data, classify the importance of alarm information, and make preparations for power grid fault diagnosis based on alarm information has become an urgent problem to be solved in online fault diagnosis. Based on this, this paper proposes an importance classification method of alarm information based on bigru attention to screen the data with the strongest correlation with fault, avoid the impact of irrelevant data on fault diagnosis, and meet the needs of intelligence. Firstly, the two-way gated loop (bigru) neural network layer is used to preprocess the alarm information text and extract the features of the deep-seated information; Secondly, the attention mechanism layer is used to assign corresponding weights to the extracted text deep-seated information; Finally, the text feature information of alarm information with different weights is put into the softmax function layer for alarm information text classification. Finally, an actual fault case in an area is tested to verify the effectiveness and practicability of the proposed method.

Deep-learning-based fault diagnosis (FD) methods have shown remarkable superiority in the field of fault prognostic and health management (PHM). However, the performance of a deep neural network relies heavily on a substantial labeled training dataset, which is rare in actual industrial scenarios. Moreover, the extracted fault features under different working conditions follow different joint distribution. As a result, a deep model trained under one condition cannot be extended to others. To address the existing problem, this paper proposes a step-by-step gradual domain adaptive neural network to conduct cross-domain FD, which can realize precise alignment between the source domain and the target domain. Firstly, the maximum mean discrepancy is used to perform primary domain adaptation. Furthermore, two classifiers are set up to limit the discrepancy of target domain data in the classification decision. Finally, the exact alignment of class-level features is achieved by category prototype alignment. The extensive experimental results show the superiority and stability of the proposed method when compared with other conventional approaches.

Mid-infrared optical parametric oscillators (OPOs) offer a compelling route for accessing the ‘molecular fingerprint’ region and, thus, can find intensive applications such as precision spectroscopy and trace gas detection. Yet it still remains rather a challenge to realize broadband mid-infrared OPOs within a single cavity, usually limited by strict phase-matching conditions for wide spectral coverage and available pump power for adequate frequency generation. Here, we report the mid-infrared parametric oscillation spanning from 3.4 to 8.2 μm, based on four-wave mixing in a high-Q MgF2 microresonator with optimized dispersion. The center wavelength at 4.78 μm is determined by the continuous tunable quantum cascade laser source, which contributes to effective expansion towards longer wavelength, as well as systemic miniaturization with smaller pump module. Such results could not only shed light on new ultimates of crystal and other microresonators, but also inspire explorations on their growing potentials in near future.

In this paper, a new space inertial sensor based on laser interferometry developed by the experimental team is used for temperature simulation analysis of multi-physics coupling. Through the analysis of the noise influence of the inertial sensor, it is calculated that under the index of the acceleration noise level of 1×10−10 g/Hz1/2, the temperature fluctuation of the Test Mass (TM) needs to be controlled ≯0.1 °C. The finite element analysis method is used to simulate and calculate the temperature change inside the inertial sensor within 36 hours. In the case of no heat insulation component, the temperature difference between the six surfaces of the TM is maintained within 10−5K, and the temperature of the Electrode Housing (EH) only fluctuates ±0.1K in the stable fluctuation section when the external environment fluctuates ±1K. After 36h, the temperature of the TM decreased by 0.007K compared with the initial value. With the addition of heat insulation components, the fluctuation range of internal temperature decreases, and the temperature of the EH fluctuates within the range of ±0.015K.

Wound treatment is a huge challenge for healthcare systems, especially when the wound suffered infection. Therefore, it is essential to develop materials with antibacterial properties for wound repair. Herein, we integrated antimicrobial peptides with self-healing hydrogel for infectious wound treatment. The synthetic hydrogel was made by polymerizing N-acryloyl glycinamide (NAGA) monomers and doped with antimicrobial peptide Polymyxin E. Additionally, because of the bisamide structure of the side chains of the NAGA monomers, the hydrogen bond was formed and caused the supramolecular structure. The resulted hydrogel showed excellent self-healing property, biocompatibility, and antimicrobial property, which allowed it to be used as hydrogel dressing. In vivo experiment demonstrated that the hydrogel had the significant capability in promoting infectious wound healing. Therefore, this type of antibacterial self-healing supramolecular hydrogel is expected to serve as infectious wound dressing for medical healthcare applications.

Crop residue burning (CRB) has been a major environmental concern in key agricultural regions of China. To reveal spatiotemporal patterns of CRB events, a county-level assessment in Northeast China was conducted using Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomalies and land cover data. The results revealed that cropland fire occurrence increased significantly from 2003 to 2019, and annual CRB occurrence from 2014 to 2019 was significantly higher than that from 2003 to 2013. The majority of detected CRB events occurred in spring and autumn, accounting for 58.50% and 28.98% of the total cropland fires, respectively. The time scan statistics showed that CRB events lasted for approximately 40 days each year and were more severe in spring than autumn. The number of cropland fires monitored by Terra and Aqua satellites was relatively more balanced, accounting for 49.74% and 50.26% of the total, respectively, indicating that farmers may intentionally burn crop residue at night. The counties with higher CRB intensity were mainly in the Songnen Plain, Sanjiang Plain, and along the main stream of the Liaohe River. The Moran’s I value of 0.054 to 0.452 for CRB intensity demonstrated a strong spatial autocorrelation at the county level. The local autocorrelation Getis-Ord G i * showed 86 counties with significant hot spots and 91 counties with significant cold spots. The county-level temporal and spatial patterns of CRB events may be the results of policies and socio-economic conditions. This study could provide support for identifying the influencing factors of CRB and offer suggestions for crop residue management practices in this agriculture-dominant region.