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This paper presents a method for early detection of dangerous condition in the deep-water zone of swimming pool based on video surveillance. We propose feature extraction, feature expression and assessment criteria, including a method for evaluating normal swimming speed based on the time series of swimmers, a method for assessing an upright state that is not limited by the camera angle, and the rules for assessing dangerous state. We have collected real-life data from the swimming pool and conducted related experiments. Our method can easily and efficiently detect the swimmer who is in danger at an early stage and provide necessary rescue reminders to lifeguards.

Objectives: To study the mechanism of acupuncture manipulation (AM) based on the secretion function and morphological variation of fibroblasts in acupoint region. Methods: 40 rabbits were randomly divided to normal group (N), model group (M), needle retaining group (A), and acupuncture manipulation group (AM), each group consist of 10 rabbits. The animal model of Rabbits with Bacterium Endotoxin Induced Fever (BEIF) was established by intravenous injection of bacterial endotoxin. Groups A and AM were treated with 'Qu Chi'(LI11) acupuncture after modeling, and acupuncture manipulations were conducted in group AM. The serum heat factors IL-1β, IL-6, and TNF-α content were assayed conducted in group AM. The serum heat factors IL-1β, IL-6, and TNF-α content were assayed by Elisa after acupuncturet; the morphological changes of fibroblasts in acupoint area were observed by Vimentin staining; the fibroblasts of subcutaneous connective tissue in acupoint area were isolated and cultured in vitro, and the contents of PEG2, NO and ATP in supernatant were assayed. Results: There was no significant difference in fibroblasts cytomorphology among groups M, A, and N. Fibroblasts in group AM were stretched and aligned in almost one direction. Comparing with group N, the content of serum IL-1β, IL-6, and TNF-α was significantly higher in group M, along with higher NO and ATP content in the cell culture supernant; Comparing with group M, content of IL-6 and TNF-α was lower in group A, content of serum IL-1β, IL-6 and TNF-α was higher in group AM, along with higher PEG2, NO and ATP content in both groups, while group AM demonstrated more significant changes in the above indicators than group A. Conclusion: Acupuncture had therapeutic effects on BEIF rabbits, the application of acupuncture manipulation can further improve its therapeutic effects. The mechanism may be related to the influence on fibroblasts cytomorphology in acupoint region and facilitation of fibroblasts-derived PEG2, NO, and ATP, which together promote the acupoint vitality.

The firing density is an important parameter to evaluate the firing effect of rapid-fire weapons, and the multi-sky-screen target testing system is widely used in the measurement of firing density of rapid-fire weapons. However, due to the influences such as the transportation, repeated installation and movement of multi-sky-screen target, the change of ambient temperature in outfield testing, and the long-time usage, the measurement error of the firing density becomes larger. For the calibration of firing density of multi-sky-screen target, a method based on double theodolites and high-accuracy bullet holes screen was proposed. The coordinates of the bullet holes in the bullet holes screen were measured by intersection measurement of double theodolites, and then the density parameters were calculated by the density formula. The calculated density parameters were compared with that of the multi-sky-screen target to complete the calibration. By the firing practice, the uncertainty of firing density measured by double theodolites combined with bullet holes screen was evaluated. The results show that the uncertainty of the firing density measured by the proposed method is 1.6 mm, which can be used for the calibration of the multi-sky-screen target density.

The membrane structure is a flexible structure, which is easy to vibrate or even relax under dynamic load. Engineering accident analysis shows that the relaxation of membrane structure is more likely to lead to structural failure. In this article, the impact load problem is combined with the flexible structure to analyze the impact of hailstone impact load on the dynamic response of membrane structure. First, the umbrella membrane stretching device was designed and manufactured, and the hailstone impact test was carried out on the umbrella membrane structure with polyvinyl chloride membrane material. Dynamic response data, tension relaxation of side cables and vibration deformation of umbrella membrane structures impacted by hailstones with different sizes and different characteristic points were obtained. In the numerical analysis, the form-finding analysis of umbrella membrane structure is carried out by finite element method, and the transient impact analysis is conducted in LS-DYNA. Finally, the reliability of the research results is verified by comparing the numerical and experimental results. The general laws and conclusions are drawn and the disaster-causing mechanism of membrane structure impacted by hailstone is revealed. On the whole, although the probability of hailstone destroying the membrane material directly is very small, it will relax the membrane structure and affect the safety of membrane structure. The conclusions of this article provide a theoretical basis for the design and maintenance of membrane structures.

The aim of this study was to develop and examine the morphology and distribution of mercury (Hg) in flue gas desulfurization (FGD) by-product. Mercury in the coal of coal-fired power plants is concentrated in the by-products of desulfurization process, and it is widely used as an additive in cement, building materials and other industries. Due to the different stability of various forms of mercury in the environment, subsequent use of products containing desulfurization by-product additives will continue to be released into the environment, endangering human health. Therefore, it is very necessary to study the form and distribution of mercury in the by-products of desulfurization in coal-fired power plants to provide a theoretical basis for subsequent harmless treatment. For content and morphology of mercury analysis, 1 sample of dry FGD ash and 6 samples of wet FGD gypsum were analyzed. The total 7 samples were extracted using a modification of sequential chemical extractions (SCE) method, which was employed for the partitioning Hg into four fractions: water soluble, acid soluble, H2O2 soluble, and residual. The Hg analysis was done with United States Environmental Protection Agency (USEPA) method 7471B. Comparing with the wet FGD gypsums of coal-fired boilers, the total Hg content in the dry FGD by-product was as high as 1.22 mg/kg, while the total Hg content in the FGD gypsum is 0.23 - 0.74 mg/kg, which was 2 times over the wet FGD gypsum. The concentration of water soluble Hg in the dry FGD by-product was the highest amount (0.72 mg/kg), accounting for 59.02% of the total mercury. While residual Hg content was 0.16 mg/kg, only about 13.11% of the total mercury. Mercury content in FGD gypsum was expressed in the form of ρ (residual Hg) > ρ (H2O2 soluble Hg) > ρ (water soluble Hg) > ρ (acid soluble Hg). The morphology and distribution of mercury in FGD by-products is supposed to be analyzed before utilization, and the impact of mercury on the environment should be considered.

Multi object tracking (MOT) is a key research technology in the environment sensing system of automatic driving, which is very important to driving safety. Online multi object tracking needs to accurately extend the trajectory of multiple objects without using future frame information, so it will face greater challenges. Most of the existing online MOT methods are anchor-based detectors, which have many misdetections and missed detection problems, and have a poor effect on the trajectory extension of adjacent object objects when they are occluded and overlapped. In this paper, we propose a discrimination learning online tracker that can effectively solve the occlusion problem based on an anchor-free detector. This method uses the different weight characteristics of the object when the occlusion occurs and realizes the extension of the competition trajectory through the discrimination module to prevent the ID-switch problem. In the experimental part, we compared the algorithm with other trackers on two public benchmark datasets, MOT16 and MOT17, and proved that our algorithm has achieved state-of-the-art performance, and conducted a qualitative analysis on the convincing autonomous driving dataset KITTI.

Visual tracking task is divided into classification and regression tasks, and manifold features are introduced to improve the performance of the tracker. Although the previous anchor-based tracker has achieved superior tracking performance, the anchor-based tracker not only needs to set parameters manually but also ignores the influence of the geometric characteristics of the object on the tracker performance. In this paper, we propose a novel Siamese network framework with ResNet50 as the backbone, which is an anchor-free tracker based on manifold features. The network design is simple and easy to understand, which not only considers the influence of geometric features on the target tracking performance but also reduces the calculation of parameters and improves the target tracking performance. In the experiment, we compared our tracker with the most advanced public benchmarks and obtained a state-of-the-art performance.

The production of high-quality tea by Camellia sinensis (L.) O. Ktze is the goal pursued by both producers and consumers. Rapid, nondestructive, and low-cost monitoring methods for monitoring tea quality could improve the tea quality and the economic benefits associated with tea. This research explored the possibility of monitoring tea leaf quality from multi-spectral images. Threshold segmentation and manual sampling methods were used to eliminate the image background, after which the spectral features were constructed. Based on this, the texture features of the multi-spectral images of the tea canopy were extracted. Three machine learning methods, partial least squares regression, support vector machine regression, and random forest regression (RFR), were used to construct and train multiple monitoring models. Further, the four key quality parameters of tea polyphenols, total sugars, free amino acids, and caffeine content were estimated using these models. Finally, the effects of automatic and manual image background removal methods, different regression methods, and texture features on the model accuracies were compared. The results showed that the spectral characteristics of the canopy of fresh tea leaves were significantly correlated with the tea quality parameters (r ≥ 0.462). Among the sampling methods, the EXG_Ostu sampling method was best for prediction, whereas, among the models, RFR was the best fitted modeling algorithm for three of four quality parameters. The R2 and root-mean-square error values of the built model were 0.85 and 0.16, respectively. In addition, the texture features extracted from the canopy image improved the prediction accuracy of most models. This research confirms the modeling application of a combination of multi-spectral images and chemometrics, as a low-cost, fast, reliable, and nondestructive quality control method, which can effectively monitor the quality of fresh tea leaves. This provides a scientific reference for the research and development of portable tea quality monitoring equipment that has general applicability in the future.

International audience

We propose and experimentally demonstrate a 16-channel flexible optical passband filter array for colorless, directionless, contentionless, flexible reconfigurable optical add/drop multiplexer. Utilizing high-resolution diffraction grating for wavelength dispersion and liquid crystal on silicon for wavelength modulation, the filter array can realize adding/dropping 16 independent optical channels with tunable bandwidth and center wavelength. Furthermore, each channel is capable of tuning multiple wavelengths with different bandwidths. The proposed filter array realized remarkable performance, such as less than 6dB insertion loss, 50GHz to 5000GHz bandwidth tuning range, transmission bandwidth covering the full C band, and greater than 30dB optical isolation among the channels.

The exploitation of natural gas hydrate is always hindered by the migration of water and sands due to gas production. Depressurization combined with thermal stimulation is an effective method for hydrate dissociation. This paper reported the influence of gas-liquid-solid migration on morphological change of hydrate sediments in natural gas production using visualization method. Different backpressures combined with thermal stimulation methods were applied to simulate natural gas hydrate exploitation. Pressure compensation was first employed to study sediment recovery features. The expansion rate of a porous medium layer under combined dissociation and different backpressure (4.5, 3.5, 2.5, 1.5, and 0.1 MPa) was discussed. A 176% hydrate sediment expansion rate was found after the combined dissociation at 0.1 MPa. In addition, it was observed that the height of the water layer above the porous media after pressure compensation was gradually reduced with a decrease in backpressure and eventually disappeared at 0.1 MPa. It was also found that the disappearing water layer caused an anomalous memory effect phenomenon. Expansion and subsidence of sediments provide a better reference for hydrate exploitation and geological safety.

The efficiency of GaAs solar cell was significantly reduced resulting from non-uniformity of energy flux-density on receiver surface, and damage of solar cells was made by “hot spots”. In this paper, a light funnel is added between the concentrator and the receiver to improve the uniformity of energy flux-density on receiver surface, which is designed according to the ray tracing method. The simulation result shows that the uniformity of the energy flux-density on the receiver surface is 92.26%, which agrees with the experimental result (94.64%). According to the maximum output efficiency of GaAs solar cell, the layout range of the cell is determined. The simulation results shown that the cell is arranged in the radius of 58 mm, which is similar to the experimental value (60 mm), and the effective area rate of the photoelectric conversion is 69.4%. At normal operation temperature (20 °C), the photoelectric conversion efficiency is 29.64%, and the total efficiency is about 83%.

An $8\times \,\,16$ wavelength selective switch (WSS) with full contentionless switching is proposed and experimentally demonstrated. Utilizing two chips of liquid crystal on silicon, the optical wavelengths can be switched, attenuated, or blocked among 8 input ports and 16 output ports. The maximum insertion loss is less than 14 dB; the bandwidth tuning range is from 50 to 5000 GHz. The attenuation range is from 0 to 15 dB, and the optical blocking value is greater than 27 dB. Compared with the previous reports, the $8\times16$ WSS proposed in this letter is a truly contentionless WSS device with the highest number of input and output ports.

A micro-cavity array (MCA) fiber based on a dense ultra-short fiber Bragg grating (FBG) array is proposed for high-accuracy fully distributed sensing. In the MCA fiber, each pair of adjacent FBGs forms a micro-cavity, which acts as the sensing element. The high finesse interference spectra of the micro-cavities facilitate high demodulation accuracy. Large-scale multiplexing of 8557 FBGs results in 8556 micro-cavities in a 7.18-m MCA fiber. Combined with optical frequency-domain reflectometry, fully distributed temperature sensing with a spatial resolution less than 1 mm and measurement precision of 0.157 °C is demonstrated.

The gearbox is one of the key components of the high-speed train system. In order to predict the fatigue damage behavior of high-speed train gearbox shell material, we propose a new method. Because the fatigue process is long and there is no whole life fatigue damage data of the shell, the performance degradation method and acceleration test with acoustic emission instrument have been used. A new Adaboost data distribution adjustment algorithm is proposed to solve the problem of data imbalance of acoustic emission signals during the fatigue process. Then a cumulative count trend model and a fatigue life prediction model are developed. The life prediction error is controlled within 400 s, most errors are less than 200 s, and the relative error is less than 1.1%, which ensures the feasibility of the developed model. In the future, this model can be used in long-time life prediction researches.

Lanthanide-doped upconversion nanoparticles (UCNPs) are promising bioimaging nanoprobes due to their excellent photostability. As one of the most commonly used lanthanide activators, Tm3+ ions have perfect ladder-type electron configuration and can be directly excited by bio-friendly near-infrared-II (NIR-II) wavelengths. Here, the emission characteristics of Tm3+-doped nanoparticles under laser excitations of different near-infrared-II wavelengths were systematically investigated. The 1064 nm, 1150 nm, and 1208 nm lasers are proposed to be three excitation strategies with different response spectra of Tm3+ ions. In particular, we found that 1150 nm laser excitation enables intense three-photon 475 nm emission, which is nearly 100 times stronger than that excited by 1064 nm excitation. We further optimized the luminescence brightness after investigating the luminescence quenching mechanism of bare NaYF4: Tm (1.75%) core. After growing an inert shell, a ten-fold increase of emission intensity was achieved. Combining the advantages of NIR-II wavelength and the higher-order nonlinear excitation, a promising facile excitation strategy was developed for the application of thulium-doped upconversion nanoparticles in nanoparticles imaging and cancer cell microscopic imaging.

Classical meta-absorber designs usually have a tradeoff between bandwidth, efficiency, and thickness. Here, we introduce the concept of a nonlocal acoustic metasurface absorber by using a bridge structure connecting resonating unit cells to improve the performances of the meta-absorber. By utilizing the coupling effect between the adjacent unit cells, ultrabroadband sound absorption is achieved with deep-wavelength thickness. The physical mechanism of the nonlocal acoustic metasurface absorber is investigated and uncovered by developing analytical models. We theoretically and numerically study the nonlocal metasurface with a connecting bridge and the traditional metasurface without a bridge. The nonlocality can introduce three specific effects: the optimization of effective acoustic impedances, the shift of Fabry-Perot resonant frequencies, and the enhancement of the coupling effects between adjacent unit cells. These effects contribute to improve the bandwidth and the efficiency of the acoustic meta-absorber. We numerically and experimentally achieve an average absorption coefficient larger than 0.9 within the ultrabroadband bandwidth extending from about 600 to 2600 Hz, with a metasurface of 6.8 cm, viz., \ensuremath{\lambda}/9 for the lowest frequency. Our finding demonstrates the advantage of nonlocal acoustic metasurface to conceive a subwavelength sound meta-absorber.

With the increasing consumption of electric energy in China, the management of power consumption becomes more and more important. It is essential for the analysis of electric appliances to make a reasonable way of electricity consumption. Aiming at the problem of low accuracy of low frequency sampling recognition, this paper proposes a non negative matrix decomposition method for feature extraction of electrical data. The peak density of feature data is calculated by peak density algorithm, and the peak density of feature data is taken as the initial cluster center of fuzzy c-means algorithm. The feature States of each device are obtained. Finally, the state sequence is processed by single and two-way long-term and short-term memory network. The accuracy of load identification is greatly improved. It shows that the proposed method has outstanding capability for device state extraction.

International audience; In this work, a tunable fish-bone elastic metasurface is used to manipulate the in-plane waves which are more complex than flexural or out-of-plane waves because of the coupling of the P-and SV-waves. First, the refracted generalized Snell's law (GSL) for mixed in-plane wave is deduced which is also testified by the numerical results. Then according to the GSL, the elastic metasurfaces are designed to realize multifunctions such as directional refraction and wave focusing for different working frequencies. The critical refraction is discussed for the directional refraction and the behavior of SV-wave is predicted when the P-wave is designed to focus at any point by the metasurface.

Increasing demand for DRAM scaling and high-bandwidth has driven DRAM technology to 3D/2.5D integration. With the innovative Hybrid Bonding technology, a new Stacked Embedded DRAM (SEDRAM) architecture was developed on LPDDR4/4X product. In this SEDRAM, a DRAM array wafer and logic wafer were fabricated separately and then face-to-face fusion connected through ultra-high-density, low-resistance Hybrid Bonding. By separating the control, I/O, DFT and periphery circuits to a logic die, SEDRAM offers a novel approach to DRAM product development and accomplishes an extremely high-bandwidth logic-to-memory interface speed of 34GBps per 1Gb with low power consumption as low as 0.88pJ/bit.

Background To study the effect of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) on the outcome of hospitalization in patients with hypertension and novel coronavirus disease 2019 (COVID-19). Methods A retrospective analysis was performed in 202 COVID-19 patients who were hospitalized in Thunder-God Hospital, Wuhan from 12 February 2020 to 30 March 2020. According to whether taking ACEI or ARB, 67 (33.0%) patients with hypertension were divided into 3 groups: A, patients received ACEI or ARB after admission (n = 22); B, patients received ACEI or ARB before admission but interrupted after admission (n = 24); and C, patients were not treated with ACEI or ARB before or after admission (n = 21). Changes of therapeutic indicators in all groups of patients and their application relationship with ACEI/ARB were compared and analyzed. Results There were no significant differences in age, gender, blood pressure, underlying disease severity, or serum biochemical indicators (ALT, LDH, creatinine, and creatine kinase levels) at admission among 3 groups (all P > 0.05). During hospitalization, there were no significant differences in COVID-19-related treatment, oxygen use, hospital mortality, recovery and discharge rate, or days of throat swab nucleic acid turning negative among 3 groups (all P > 0.05). The proportion of calcium channel blocker in groups B and C was higher than group A (95.8% and 85.7% vs. 40.9%, P < 0.01), but there was no significant difference in blood pressure or compliance rates at discharge (P > 0.05). Group A, B, and C patients were hospitalized for 27.4 ± 6.4, 30.0 ± 8.8, and 30.1 ± 9.3 days, respectively (all P > 0.05). Compared with admission values, there were no significant differences in serum ALT, LDH, creatinine, or creatine kinase levels among all 3 groups during hospitalization (all P > 0.05). Conclusions ACEI or ARB has no significant effect on the outcome of hospitalization in patients with hypertension and COVID-19.

The large scale of renewable energy has brought new challenges to the frequency stability and higher requirements on frequency regulation capability. So it is necessary to control wind turbines to provide frequency regulation. Integrated inertial control can provide inertia support and primary frequency regulation for the power grid, and it can improve system frequency characteristics, which is an effective way to maintain the frequency stability of the power system with high penetration of renewable generations. The frequency controller parameters determine the frequency regulation effect, which also influence the operation and mechanical wear of the wind turbines. Based on the principle of integrated inertial control, the influence of frequency controller parameters on the frequency response characteristics was theoretically analyzed, and a segmented tuning method of frequency controller parameters with frequency stability constraints is proposed in this paper. Then system frequency response model including different types of generators were then established for parameters tuning and simulation. Finally, a four-machine two-area system is utilized to validate the proposed frequency controller parameters tuning method. The result shows that the proposed method will be helpful to improve the frequency stability of the system.

A broadband elastic wave absorption by a sub-wavelength and lightweight structure is of considerable significance in vibration suppression, especially for low frequencies in plate-like structure. However, it has always been a great challenge. In this research, we systematically study the flexural wave diffraction in a thin plate. Based on the diffraction mechanism, we propose the concept of sub-wavelength lossy gradient elastic metasurface for flexural wave absorption. We theoretically reveal high-efficiency and quasi-omnidirectional absorption behavior, which stem from maximum multireflection-enhanced absorption of the 0th order diffraction. We experimentally demonstrate a robust high-efficiency absorption in the frequency range from 343 to 1000 Hz (larger than 1.5 octaves). In addition, we propose a general approach which involves new physics of adjusting an arrangement sequence of subunits to suppress the first-order diffraction mode. This allows to further reduce the sub-wavelength thickness of the metasurface while maintaining its high-efficiency absorption. Our designs could provide new routes to broadband vibration suppression and cancelation in low frequency by lossy elastic metamaterials and metasurfaces.

This study aimed to propose a new type of micro-pressure swirl reactor (MPSR) to treat urban sewage. The MPSR could form a stable swirl in the reactor, and realized the coexistence of anaerobic, anoxic, and aerobic zones in a single aeration tank. The pilot study showed that MPSR achieved high removal efficient of SS, COD, NH4+-N, TN, TP under the conditions of drastic fluctuation in influent quality and temperature, and the average removal rate were 88.58%, 93.32%, 94.47%, 73.19%, 96.16%. The relative high abundance of Thermomonas, Thaurea, and Dechloromonas, etc, guaranteed the denitrification efficiency of the MPSR, and Dechloromonas was the main phosphorus removal bacteria in the system. The study confirmed the rationality of the structural design of the MPSR, and it was excellent in sewage treatment and stability.

Background To investigate the effects of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blockers (ARBs) administration to hypertension patients with the coronavirus disease 2019 (COVID-19) induced pneumonia. Methods We recorded the recovery status of 67 inpatients with hypertension and COVID-19 induced pneumonia in the Raytheon Mountain Hospital in Wuhan during February 12, 2020 and March 30, 2020. Patients treated with ACEI or ARBs were categorized in group A (n = 22), while patients who were not administered either ACEI or ARBs were categorized into group B (n = 45). We did a comparative analysis of various parameters such as the pneumonia progression, length-of-stay in the hospital, and the level of alanine aminotransferase (ALT), serum creatinine (Cr), and creatine kinase (CK) between the day when these patients were admitted to the hospital and the day when the treatment ended. Results These 67 hypertension cases counted for 33.17% of the total COVID-19 patients. There was no significant difference in the usage of drug treatment of COVID-19 between groups A and B (p > 0.05). During the treatment, 1 case in group A and 3 cases in group B progressed from mild pneumonia into severe pneumonia. Eventually, all patients were cured and discharged after treatment, and no recurrence of COVID-2019 induced pneumonia occurred after the discharge. The length of stays was shorter in group A as compared with group B, but there was no significant difference (p > 0.05). There was also no significant difference in other general parameters between the patients of the groups A and B on the day of admission to the hospital (p > 0.05). The ALT, CK, and Cr levels did not significantly differ between groups A and B on the day of admission and the day of discharge (p > 0.05). Conclusions To treat the hypertension patients with COVID-19 caused pneumonia, anti-hypertensive drugs (ACEs and ARBs) may be used according to the relative guidelines. The treatment regimen with these drugs does not need to be altered for the COVID-19 patients.

Virtual inertia control of wind turbines can provide frequency regulation for the power grid, which is an effective way to maintain the frequency stability of the power system with high penetration of renewable generations. The arrangement of virtual inertia control and the tuning of the virtual inertia controller parameters determine its frequency support effect and system frequency response, which also influence the operation and mechanical wear of the wind turbines. In this paper, the selection of the virtual inertia controller parameters is investigated from the system level considering the power disturbances possibility. First, the power disturbances possibility of a power system with high penetration of wind power is discussed considering the fluctuations of wind power and disturbances of the loads. Then, the requirement of the system inertia to maintain the frequency stability (frequency response indices in the limited ranges) is investigated, and the inertia needed from the wind turbines is calculated according to the requirement. Finally, the IEEE 10 machine 39 bus power system model is utilized to validate the proposed virtual inertia controller parameter tuning method. The proposed method will be helpful for deploying the frequency control strategies of the power system with high penetration of wind power and maintain its frequency stability.

At present, Voltage Source Converter based High Voltage Direct Current Transmission (VSC-HVDC) is widely used in connecting OWF to the main power system. Different from onshore wind farms, OWFs are decoupled from the system frequency due to VSC-HVDC connection, so the traditional onshore wind farm frequency control strategy cannot be directly applied, which brings new challenges to the frequency support in onshore system when The frequency fluctuation. The VSC-HVDC connected OWFs has the rotational kinetic energy in the wind turbines’ rotor and the DC capacitor electrostatic energy of the VSC-HVDC system which could be utilized for frequency control. Based on the characteristics of the two power sources, a coordinated frequency control strategy which can suppress secondary frequency drop and assist the rotor speed recovery of the wind turbine was proposed. By means of this strategy, the onshore power system frequency nadir and rate of change of frequency are reduced. And the second frequency drop caused by the rotor speed recovery of wind turbines could be limited. A low-inertia power system model in Matlab/Simulink is used to testify the effectiveness of the strategy.

Background: Recently, the community rehabilitation model for schizophrenia patients has become increasingly popular, and the Shanghai Pudong New Area has developed a relatively complete community rehabilitation model. This study analyzed the correlation between family function and subjective quality of life in the rehabilitation of patients living with schizophrenia in the community. Methods: This study evaluated persons living with schizophrenia using the Family Assessment Device and the Subjective Quality of Life Scale. A convenient sampling method was used to select 281 rehabilitation patients living with schizophrenia in the community and 166 hospitalized persons living with schizophrenia. Results: There was a significant difference in the Family Assessment Device scores between rehabilitation patients living with schizophrenia in the community and hospitalized persons living with schizophrenia (p &lt, 0.0001). The difference in the scores of the subjective quality of life assessment between rehabilitation patients living with schizophrenia in the community and hospitalized persons living with schizophrenia was not statistically significant (p &gt, 0.05). The regression analysis showed that quality of family function had a significant effect on the subjective quality of life in rehabilitation patients living with schizophrenia in the community and hospitalized persons living with schizophrenia. (F = 10.770 p &lt, 0.001), (F = 2.960 p &lt, 0.01). Conclusions: The quality of family function plays an important role in improving the subjective quality of life in rehabilitation patients living with schizophrenia in the community. It may be beneficial to add some methods to improve family function in the current model of rehabilitation in the community.

Background and aim There are important public health issues involving rehabilitation of patients living with schizophrenia in the community. The purpose of this study was to analyze the correlations between number of previous hospitalizations, living space and quality of family function in the rehabilitation of patients living with schizophrenia in the community. The study attempts to determine the potential ways to use beneficial factors in recurrent hospitalization for improving treatment and rehabilitation efforts for patients living with long-term chronic schizophrenia. Methods The study included 281 rehabilitations of patients living with schizophrenia in the community. A homemade general questionnaire was used to collect information about the number of previous hospitalizations and the living space of the participants. A family assessment device was used to evaluate the quality of family function of the patients. Results The number of previous hospitalizations of persons living with schizophrenia in the community was negatively correlated with the quality of family function (B = 0.063), and there was no statistical difference in the number of previous hospitalizations and the quality of family function of patients in different living spaces. Conclusions The number of previous hospitalizations had a negative impact on family function in the rehabilitation of patients living with schizophrenia in the community. Living space may not have a significant positive effect on family function or the number of previous hospitalizations.

High-precision wireless localization has attractive application prospects. Cooperative localization is an effective tool to improve localization accuracy. However, compared with non-cooperative localization, in cooperative localization networks, large-scale neighboring links and nonlinear measurement functions cause the associated objective function to be non-convex. It is difficult to obtain global optimum using classical particle swarm optimization (PSO) algorithm or analytical methods. In order to solve this problem, a classified particle swarm optimization (CPSO) algorithm is proposed in this paper. For classical PSO, all search particles have the same inertial weight and learning factor. Unlike classical PSO, the proposed CPSO algorithm classified different search particles based on particle cost value and set different inertial weights and learning factors for search particles. Meanwhile, considering the unavoidable reference node location error, localization result could be achieved by calculating the weighted average of close-range particle locations. Simulation results prove that the CPSO algorithm improves positioning accuracy by 25.3% compared with classical PSO algorithm.

International audience; The discovery of the disorder effect in traditional metamaterials has opened the possibilities in the search for the disordered metasurfaces. Photonic, dielectric and elastic metamaterials exhibiting the added value of the disorder effect on wave propagation physics, have been reported. Despite this extensive attention and progress in disordered metamaterials, the elastic metasurfaces however, involving disorder have not yet been reported. Here, we introduce the concept of disordered elastic metasurface composed of identical pillared resonators with a random arrangement in the subwavelength range. Based on theoretical formalism and direct acoustic measurement, we observe anomalous deflection and focusing effects of flexural waves in a plate, and elucidate in details the related physics. This research extends the disorder effect to metasurfaces and may lead to innovative acoustoelastic devices.

Microbes on aging flue-cured tobaccos (ATFs) improve the aroma and other qualities desirable in products. Understanding the relevant organisms would picture microbial community diversity, metabolic potential, and their applications. However, limited efforts have been made on characterizing the microbial quality and functional profiling. Herein, we present our investigation of the bacterial diversity and predicted potential genetic capability of the bacteria from two AFTs using 16S rRNA gene sequences and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) software. The results show that dominant bacteria from AFT surfaces were classified into 48 genera, 36 families, and 7 phyla. In addition, Bacillus spp. was found prevalent on both ATFs. Furthermore, PICRUSt predictions of bacterial community functions revealed many attractive metabolic capacities in the AFT microbiota, including several involved in the biosynthesis of flavors and fragrances and the degradation of harmful compounds, such as nicotine and nitrite. These results provide insights into the importance of AFT bacteria in determining product qualities and indicate specific microbial species with predicted enzymatic capabilities for the production of high-efficiency flavors, the degradation of undesirable compounds, and the provision of nicotine and nitrite tolerance which suggest fruitful areas of investigation into the manipulation of AFT microbiota for AFT and other product improvements.

International audience; We theoretically and experimentally propose two designs of broadband low-frequency acoustic metasurface coiled absorbers (Sample I/Sample II) for the frequency ranges of 460 Hz–972 Hz and 232 Hz–494 Hz (larger than 1 octave), with absorption larger than 0.8 (average is 0.87), and having the ultra-thin thickness of 4.5 cm and 9 cm respectively (λ/17 for the lowest working frequency and λ/8 for the highest frequency). The designed supercell consists of 16 different unit cells corresponding to 16 eigen frequencies for resonant absorptions. The coupling between multiple resonances leads to broadband absorption effect in the full range of the targeted frequency spectrum. In addition, the coiling structure lead to the ultra-thin thickness of the metasurface absorbers. Our conceived ultra-thin low-frequency broadband absorbers may lead to pragmatic implementations and applications in noise control field.

In this paper, a polymer waveguide sensor based on localized surface plasmon resonance (LSPR) of gold nanoparticles was demonstrated. Gold nanoparticles with diameter of 20 nm were synthesized. Polymer SU-8 3050 material was used as core material to fabricate waveguides by standard photolithography. After silanization process, gold nanoparticles were efficiently and firmly bound to the polymer waveguide surface. Different concentrations of NaCl solution with the refractive index between 1.342 and 1.379 were detected by the polymer waveguide sensor coated with gold nanoparticles. A set of test system for polymer waveguide sensor was established and used to do the absorbance test in NaCl solution. The sensitivity is $\mathbf{4.016\Delta\ A/RIU}$ which is about 38 times higher than that of polymer film.

X-ray spectrum nondestructive testing of electric power fittings is able to provide convenient, quick and accurate detection. The principles of X-ray and detection methods are introduced in this paper. By changing the steel anchor and external aluminum sleeve crimping parts, core wire and anchor pipe or core wire connecting pipe crimping size, external tube and wire or intermediate casing crimping size, X-ray detection technology is used to detect the actual crimping size, and the influence of typical defects on crimping quality of transmission line fittings are analyzed. It is proved that X-ray digital imaging technology is effective in nondestructive testing of the quality of transmission line fittings, and X-ray digital imaging technology can be widely applied in the quality inspection of wire bonding.

We proposed a novel salient object detection based on quaternionic local ranking binary pattern and high-level priors. Firstly, we employed a edge-preserving smoothing algorithm to smooth the minor variations within textures. Secondly, we adopted a local descriptor called quaternionic local ranking binary pattern (QLRBP) for smooth image, and got three feature maps. Futhermore, we presented a saliency measurement method based on Shannon entropy and L 2 norm for the feature maps. Finally, we combined the two level priors with feature maps to generate three initial salieny maps, and we obtained final saliency map by the saliency measure method. The experimental results demonstrate that our method is effective and efficient.

Generating structural query language (SQL) queries from natural language is a long-standing open problem. Answering a natural language question about a database table requires modeling complex interactions between the columns of the table and the question. It has been attracting considerable interest recently and driven by the explosive development of deep learning techniques. In this paper, we apply the sketch-based approach or synthesizing way to solve this problem. Based on the structure of SQL queries, we break down the model to three sub-modules and design specific deep neural networks for each of them. We employ the bidirectional attention mechanisms and character-level embedding with convolutional neural networks (CNNs) to improve the result. Experimental evaluations show that our model achieves the state-of-the-art results in WikiSQL dataset.

In this paper, we present a framework for automatic collection and update of "Honor & Black" list. Based on natural language processing, crawler and big data technology, we firstly collect the "Honor & Black" list drawn up by the member units of the joint inter-ministerial conference on the construction of social credit system in China or the competent authorities of other industries. Then we build the "Honor & Black" list database, and automatically update the "Honor & Black" list database according to the laws and regulations of joint rewards, punishments and the credit repair situation of credit subjects. This paper lays a foundation for improving the joint reward and punishment system and promoting the sharing of social credit information.

International audience; We theoretically and experimentally investigate a helical acoustic metasurface capable of providing a modulated sound-reflected wavefront and a continuously tunable broadband feature. Compared to existing metasurface designs, which mostly manipulate acoustic waves in a fixed or narrow frequency range, the matched screw-and-nut mechanism has added value and unusual properties, opening a realistic solution to achieve broadband tunability of acoustic metasurfaces with multifunctions. The conceived tunable metasurface is composed of identical units, which consist of matched screws rotated into helical channels from bottom to top to modulate the sound-reflected wavefront pattern. As a pragmatic example, we present the design details and functionalities of a flat metasurface operating at a wide working band. Then a sample of the metasurface is manufactured with the three-dimensional (3D)-printed cylindrical units to experimentally demonstrate the continuously tunable multifunction, including anomalous reflection, arbitrary focusing, and self-bending beams. All results are in good agreement. The proposed spiral matching concept could open up an alternative avenue for broadband tunable metasurfaces of reflected wavefront modulations and associated applications.

Precisely-microstructured hydrogels via ultrafast laser processing have triggered a wide range of multi-functional applications such as artificial muscle, self-folding or biological robotics. Herein, we modify polarization of pulsed laser and wavelength to optimize the structural fixity and feature improvement of nanowires/microarchitectures in ultrafast laser processing. Paralleling linear polarization with laser scanning direction of suitable laser wavelength is demonstrated as key factor improving feature size during 3D formation of two-photon hydrogelation.

The beetle Cyrtotrachelus buqueti is the primary defoliator of bamboo in China, and causes significant economic losses and influences the development of an ecological barrier. This study aimed to identify the geographic distribution of Cyrtotrachelus buqueti and its major areas of occurrence, analyze the bioclimatic characteristics favorable for Cyrtotrachelus buqueti, and formulate measures for early warning, monitoring, and control of this pest. Analyses of suitable bioclimatic characteristics were carried out using Maxent software, and the spatial distribution and model fit were analyzed using ArcGIS and Matlab. We found that temperature annual range had the greatest contribution to the distribution of Cyrtotrachelus buqueti according to jackknife test. Mean temperature of coldest quarter (3–12 °C) and mean temperature of driest quarter (4–12 °C) were also important to this pest. The occurrence of Cyrtotrachelus buqueti complied with a t location-scale distribution (α = 0.1% confidence level) in terms of longitude, a generalized extreme-value distribution (α = 0.1% confidence level) in terms of latitude, and a log-logistic distribution (α = 0.1% confidence level) in terms of elevation. The hazard centroid has changed considerably over time in terms of these variables. The regions most damaged by Cyrtotrachelus buqueti were in southeastern parts of Sichuan Province (103.6°E, 29.2°N, elevation 400 m). Keywords: Cyrtotrachelus buqueti, Bioclimatic characteristics, Geographic distribution, Bamboo

We introduce a multi-coiled acoustic metasurface providing a quasi-perfect absorption (reaching 99.99% in experiments) at extremely low-frequency of 50 Hz, and simultaneously featuring an ultrathin thickness down to {\lambda}/527 (1.3 cm). In contrast to the state of the art, this original conceived multi-coiled metasurface offers additional degrees of freedom capable to tune the acoustic impedance effectively without increasing the total thickness. We provide analytical derivation, numerical simulation and experimental demonstrations for this unique absorber concept, and discuss its physical mechanism which breaks the quarter-wavelength resonator theory. Furthermore, based on the same conceptual approach, we propose a broadband lowfrequency metasurface absorber by coupling unit cells exhibiting different properties.

Massive machine-type communications (mMTC) is a major use case in the fifth generation (5G) wireless networks. mMTC aims at supporting a large number of Internet of Things (IoT) connections within a coverage area. The current random access procedure in the Long Term Evolution (LTE) networks may not be able to handle a large number of simultaneous connection requests due to the limited number of random access preambles. Hence, it is essential to modify the random access procedure to support mMTC. In this paper, we propose a new preamble sequence design in which two Zadoff-Chu preamble sequences are aggregated together. This design enables us to have a larger set of random access preambles consisting of all combinations of pairing two Zadoff-Chu preamble sequences. Moreover, we consider a subset of all combinations that satisfy a certain maximum peak-to-average-power-ratio (PAPR) threshold criterion to reduce the energy consumption of the IoT devices. The proposed design requires only minor changes in the conventional transmitter and receiver design for generating and decoding the aggregated preamble sequences, respectively. Results show that the proposed design reduces the probability of preamble collision to less than 10^{-4}, which is lower than LTE. Furthermore, it outperforms other collision avoidance techniques such as access class barring (ACB) in terms of a lower average total service time. The modified receiver detects the aggregated preambles successfully and avoids detecting false preambles. Both the probabilities of misdetection and false alarm are less than 10^{-3} when the signal-to-noise ratio (SNR) is larger than -7 dB.

The relative optical gains at three near infrared wavelengths (1550 nm, 1064 nm, and 980 nm) were achieved in NaYF4: Er3+, Yb3+ nanoparticle-doped SU-8 waveguides when using two low-cost light-emitting diodes (LEDs) instead of traditional 980 nm semiconductor laser as pump source. The polymer waveguides were fabricated by one-step photolithography process. The fluorescence bands around 1550 nm and 1000 nm wavelengths due to the 4I13/2 → 4I15/2 transition of Er3+ ions and 2F5/2 → 2F7/2 transition of Yb3+ ions were observed under the excitation of 405 nm and 520 nm LEDs. By using the vertical top pumping mode of LEDs, the relative gains of 4.2 dB, 1.7 dB, and 2.1 dB at 1550 nm, 1064 nm, and 980 nm wavelengths were achieved, respectively, on a 10-mm-long waveguide.

Acoustic holograms have promising applications in sound-field reconstruction, particle manipulation, ultrasonic haptics and therapy. This paper reports on the theoretical, numerical, and experimental investigation of multiplexed acoustic holograms at both audio and ultrasonic frequencies via a rationally designed transmission-type acoustic metamaterial. The proposed meta-hologram is composed of two Fabry-Perot resonant channels per unit cell, which enables the simultaneous modulation of the transmitted amplitude and phase at two desired frequencies. In contrast to conventional acoustic metamaterial-based holograms, the design strategy proposed here, provides a new degree of freedom (frequency) that can actively tailor holograms that are otherwise completely passive and hence significantly enhances the information encoded in acoustic metamaterials. To demonstrate the multiplexed acoustic metamaterial, we first show the projection of two different high-quality meta-holograms at 14 kHz and 17 kHz, with the patterns of the letters, N and S. We then demonstrate two-channel ultrasound focusing and annular beams generation for the incident ultrasonic frequencies of 35 kHz and 42.5 kHz. These multiplexed acoustic meta-holograms offer a technical advance to tackle the rising challenges in the fields of acoustic metamaterials, architectural acoustics, and medical ultrasound.

A 980 nm semiconductor laser is always selected as the pump source for erbium-ytterbium co-doped optical waveguide amplifiers. In this work, two low-cost blue-violet LEDs, rather than an expensive 980 nm laser, were used to pump an Er3+-Yb3+ co-doped phosphate planar waveguide. When the signal power was 0.4 mW at a 1550 nm wavelength, internal optical gains of about 4.1 and 4.5 dB/cm were respectively obtained under the excitations of a 32 mW/cm2, 275 nm LED and a 914 mW/cm2, 405 nm LED. It was found that 51.17% of the total Er3+ ions in the 2H9/2 state contributed to the luminescence at 1550 nm, and a theoretical model of gain simulation was established under the excitation of a 405 nm LED. The calculated gain of about 4.1 dB/cm was found to be in accordance with the experimental optical gain results.