Sound event detection technology can identify the types of events in an audio segment and mark the start and end time of each event. It has great potential in application scenarios such as smart cities, medical monitoring, and wildlife protection. It is an important issue in the field of machine hearing subject research. Firstly, this paper reviews sound event detection methods from two aspects of supervised learning and semi-supervised learning. Then, summarizes and analyzes the features, detection models and their performances used in existing research. For supervised learning, machine learning methods and deep learning methods are highlighted. For semi-supervised learning, four effective methods based on mean teacher, co-training, multi-scale convolution and attention mechanism are summarized. Finally, common datasets and evaluation metrics are introduced, and possible future research directions are discussed, including voice separation preprocessing, domain adaptation of synthetic data and real data, self-attention model optimization, feature selection and fusion, streaming system modeling and other issues.

The widely-use of lithium-ion batteries leads to the rapid growth of spent lithium-ion batteries. Recycling of spent lithium-ion batteries can relieve the dual pressure of resource shortage and environmental pollution. This paper summarizes the technologies of recycling of spent lithium-ion batteries from the aspects of pretreatment of spent lithium-ion batteries, recovery of metal elements, and regeneration of positive and negative active materials. The future development of recycling technology is prospected.

Itch is a normal symptom in many skin diseases such as atopic dermatitis, prurigo nodularis, psoriasis, and chronic urticaria. More and more data show that interleukin-31 (IL-31) plays an important role in itch. IL-31 is composed and released from CD4⁺ help T cell, mast cells, keratinocytes, macrophages, and dendritic cells. By activating interleukin-31 heterodimer receptors (IL-31 receptor A and tumor suppressor M receptor), itch related signals are generated. Although it has been found that IL-31 can transmit itch signals to the central nerve system directly or indirectly, mechanism of itch is not fully understood. This review summarizes the current knowledge on IL-31's gene, source, receptor, and the effect of IL-31 in pruritic diseases.

In order to solve the complex control problem of the trajectory tracking of four-wheel autonomous vehicles, a new full model-free adaptive coordinate compensation integral sliding mode constraint control scheme is proposed. The control scheme only needs the I/O data of the trajectory tracking of the autonomous driving vehicle, and does not involve the vehicle model information, that is, the input data of the front wheel angle and the output data of the body angle. Therefore, this new scheme can realize trajectory tracking control for the trajectory tracking systems of different vehicle models. In the process of trajectory tracking, only controlling the body angle is easy to cause the deviation of the tracking trajectory. In this paper, firstly, a coordinate compensation algorithm is added on the basis of the full-format model-free adaptive control. Secondly, in order to improve the robustness of the system during operation, an integral sliding mode control is added. Thirdly, to deal with the system running in the saturation region in the process of sliding mode control, dynamic compensation is designed to make the trajectory tracking system run in the linear region of sliding mode control. Finally, a simulation comparison among the model-free adaptive integral sliding mode constraint control scheme, the prototype model-free adaptive control algorithm and the PID algorithm is carried out. The results show that the proposed algorithm has better control performance than traditional control methods. The tracking fluctuation error is within 0.09%. The stabilization time is within 0.5 s, and the tracking curve is smooth.

In order to effectively improve the travel time estimation accuracy of urban expressway sections, this paper presents a travel time estimation method based on adaptive filtering and grid virtual vehicle. The velocity data between fixed detectors are obtained by adaptive smoothing filter interpolation, and the spatiotemporal velocity field between fixed detectors is reconstructed. Then the reconstructed velocity field is subdivided into several grid elements. The road travel time is estimated by calculating the virtual trajectory of the virtual vehicle in the reconstructed space-time velocity field. Finally, the measured data of induction coil on urban expressway are selected for example verification.The experimental results show that the root mean square error of this method is 0.15, 0.35 and 1.06, respectively, and the average relative error is less than 10%, so it has high estimation accuracy.

As a nonlinear system with many state variables and strong coupling, the permanent magnet synchronous motor (PMSM) is prone to bifurcation, chaos and other dynamical behaviors during actual operation. The existence of these nonlinear behaviors makes the PMSM system generate chaotic oscillation states under certain operating conditions, which affects the stable operation of the motor drive system. To solve this problem, a single-state variable-based feedback tracking control method is proposed, which effectively suppresses the chaotic behavior of the PMSM system and enables the system to track to a pre-set desired reference value, which is not only fast to control, but also the error value between the tracked PMSM system and the pre-set target system can be zero. In addition, the proposed control method does not have some constraints inside the system, and the system can be tracked to any preset value simply by selecting a suitable control gain E, which greatly improves the applicability of the controller. The effectiveness of the method is proved by a large number of numerical simulation experiments.

A novel current-mirror operational transconductance amplifier was designed to overcome the disadvantages of low gain and small swing rate in traditional low-voltage micro-power current-mirror operational transconductance amplifier. Without affecting the static power consumption and stability of the circuit, the operational transconductance amplifier adopted gain boosting(GB)structure to increase the small signal gain of the circuit; the switched slow rate enhancement(SSRE)structure was introduced to improve the large signal swing rate of the circuit. The circuit was designed and simulated based on UMC 0.11μm standard CMOS process. The simulation results show that under 1.2 V power supply voltage and 10 pF load capacitance, and compared with the traditional current mirror operational transconductance amplifier, the gain of the new current mirror operational transconductance amplifier is increased by 47 dB, the positive slew rate is increased by 11.2 times and the negative slew rate is increased by 12.4 times.

To solve the problem that stacked capsule autoencoder has slow detection performance and cannot better mine local features of images, an optimization algorithm of stacked capsule autoencoders based on manifold regularization was proposed. Firstly, by using the Scharr filter to reconstruct the image in the stacked capsule autoencoders model, the accuracy of image target detection was enhanced.Then, a manifold regular term was introduced into the loss function to enhance the extraction of local features in the original data space.Finally, the stacked capsule autoencoders based on manifold regularization was used to learn parameters to select more discriminative features. Experiments results on MNIST and Fashion MNIST datasets show that compared with the original network structure, the accuracy of image classification is improved by 0.26% and 9.23%, respectively, which greatly improves the training speed of the model.

Isolation is one of the most important means to control the epidemic spreading, and the control timing and strength have great significance in the control effects. To find the most appropriate control timing and strength, in this paper, and based on uncorrelated random scale-free network and SIR spreading model, the effects of control timing and strength on the range of infectious disease spreading and individual activity are studied. The results show that if the control mode is to control the infectious state only, in both of the scale-free network model and in the real scale-free networks, when the control strength keeps the same, the earlier the control time is, the better the control effect is, and when the control time is the same, the greater the control effort is, the better the control effect is. Whether in the network model or in the real networks, the change of individual activity is non-monotonous: when the control strength is unchanged, the individual activity decreases first and then increases with the increase of control time, indicating that the number of total individuals whose activities are controlled earlier or later at the end of the epidemic transmission is less, and more infected individuals will need to be controlled when control is started around the peak of infectious disease transmission; When the control time is unchanged but before the peak value, the individual activity also decreases first and then increases, while after the peak value, the individual activity decreases monotonously.To sum up, the earlier the control time is, the greater the control force is, the better the control effect will be, and the less the individual will be affected. That is, if the strongest control strength 1 is used at the first step after the epidemic is observed, the best control effect will be achieved. The transmission range will be reduced from 55.9% to 0.1%, and only 0.2% of the total population will be controlled.

The connectedness of the strong efficient solution set for vector equilibrium problems in reflexive Banach spaces is studied in this paper. A new nonlinear function is established, and a non-convex non-closed set and a compact set can be separated by the new nonlinear function. It is shown that the solution set of the strong vector equilibrium problems equals to the union of the solution set of a series of non-linear scalar problems. The connectedness of the strong efficient solution set for vector equilibrium problems is obtained.

A delayed HIV model of intracellular infection with saturated infection rate and antibody immune response is presented here. Including uninfected cells, latently infected cells, infected cells, free HIV virus, and CTLs. The following four delays are considered: latently infected delay, intracellular delay, the time lag between an infected cell and a virus, and CTL response delay. Two threshold conditions are defined: infection reproduction number R₀ and CTL immunity-activated reproduction number R₁. It obtains three equilibria of this model: disease-free equilibrium, immune-free infection equilibrium and immune-activated equilibrium. By analyzing the characteristic equation, Lyapunov function and LaSalle's invariance principle, the locally and globally asymptotic stable criteria of each equilibrium are established.

Let R be a ring. An elemente in R is called a quasi-idempotent if there is a central unit k of R such that e²=ke. If for every element a of R, there exists a quasi-idempotent e∈R and a quasinilpotent q∈R^qnil such that e∈comm²(a) and a=e+q,then R is called a strongly quasinil quasi-clean ring. If for every element a of R, there exists a quasi-idempotent e∈R such that e∈comm²(a),a+e∈U(R) and ae∈R^qnil,then R is called a quasi-quasi-polar ring. In this paper, it is proved that the quasi-quasi-polar ring and quasi-polar ring are equivalent; every strongly nil quasi-clean ring is a strongly quasinil quasi-clean ring; and every strongly quasinil quasi-clean ring is a quasi-polar ring. The inverses are not hold.

The compounds were isolated and purified from Stachys geobombycis by column chromatography with silica gel, Sephadex LH-20 and semi-preparative HPLC, and their structures were identified by modern spectral data. Fourteen compounds were isolated and identified as tyrosol (1), nicotinamide (2), 2, 2-bis[4-(2, 3-dihydroxypropoxy) phenyl] propane (3), vanillic acid (4), syringate (5), 5-(α-D-galactopyranosyl-(1-6)-α-D-galactopyranosyloxymeth-yl)-2-furancarboxaldehyde (6), 8-O-acetyl harpagide (7), martynoside(8), dibutyl phthalate (9), tatarine C-4′-O-β-D-glucopyranoside (10), bis (2-ethylhexyl) benzene-1,2-dicarboxylate(11), (5-(α-D-galactopyranosyloxymethyl)-2-furancarboxaldehyde) (12), 5-hydroxymethyl-furaldehyde (13) and n-butyl pyroglutamate (14). Among them, compounds 1-4 and 6-14 were isolated from the S. geobombycis for the first time.

Twenty-one compounds of Ludwigia adscendens (L.) Hara were isolated and purified by silica gel,macroporous adsorption resin, Sephadex LH-20 chromatography, preparative liquid chromatography and so on. According to physicochemical properties and MS, NMR spectral data, their structures were identified as 5-hydroxy-3,4-dimethyl-5-(3-methoxyl-3-oxopropyl)-furan-2(5H)-one (1), methyl pyroglutamate (2), blumenol A (3), S(+)-dehydrovomifoliol (4), 3-isopropyl-5-acetoxy cyclohexene-2-one-1 (5), methyl hematinate (6),ethyl gallate (7), vanillic acid (8),dibutylphthalate (9), 2,3-dihydro-4(1H)-quinolone (10), syringic acid (11), 2,4-di-tert-butylphenol (12), gallic acid (13), scopoletin (14), 4-methyl-5,6-dihydro-2-pyranone (15),loliolide (16), urolithin A (17),chakyunglupulin A (18), N-benzoyl-L-phenylalaninol (19),pinonesinol (20) and aurentiamide (21). Among them,compound 1 was a new compound named ludwigolide A, and compounds 2-12, 14-21 were isolated from L. adscendens for the first time.

Multi-functional cotton fabric (CO) can expand the application range of cotton fabric. In this paper, a multi-functional cotton fabric (PDMS/RGO-CO) with UV resistance and super hydrophobicity was prepared for the first time by combining n-hexane and ethyl acetate as the co-solvent of polydimethylsiloxane (PDMS) and reduced graphene oxide (RGO). The optimum condition was developed by changing the mixture ratio of n-hexane and ethyl acetate, impregnation times with cotton fabric immersed in RGO dispersion and PDMS concentration. The results showed that multi-functional cotton fabric (PDMS/RGO-CO) had the best super hydrophobicity when the volume ratio of n-hexane to ethyl acetate was 7∶3, the impregnation times of cotton fabric was 2 times, the PDMS concentration was 100 g/L, the contact angle (CA) was 165.9°, and the ultraviolet protection coefficient (UPF) was 544.46. At the same time, PDMS/RGO-CO also showed excellent anti-fouling performance and oil-water separation ability.

The mice carrying mutant Sdr9c7 gene with loxP site in the intron regions on both sides of its exon 2 were mated with K14-Cre mice, and their offspring were hybridized to obtain epithelial cell Sdr9c7 gene specific knockout mice. The offspring genotyped with Sdr9c7^fl/flK14Cre⁺ were regarded as Sdr9c7 gene epithelial cell conditional knockout mice. Phenotype of mice was observed under stereoscope, HE stained skin paraffin sections were prepared for microscopic observation of the morphological structure of mouse skin, and the barrier function of mouse skin was detected by toluidine blue stain permeation assay. The results revealed that Sdr9c7^fl/flK14Cre⁺ mice exhibited skin cyanosis and died within 6 to 8 hours after birth. HE staining revealed Sdr9c7^fl/flK14Cre⁺ mice had abnormal skin stratum corneum structure which was tightly accumulated. Toluidine blue stain permeation assay showed that the stain could pass through the skin barrier of Sdr9c7^fl/flK14Cre⁺ mice and stain the skin darker, indicating that the epidermal barrier function was disrupted.

Affected by changes in light or endogenous hormones, some physiological phenomena and behaviors of organisms show diurnal fluctuations. In order to understand how the photoperiod of the environment affects the onset time of daily activities of the crocodile lizard, the study investigated the relationship between the awakening time of the crocodile lizard and the first activity time after waking up, and the time of dawn and sunrise in Guangxi Daguishan Crocodile Lizard National Nature Reserve. The results showed that: (1) The crocodile lizard waked up before sunrise, and there was a linear relationship between the awakening time and the dawn time (y=1.098 6x-0.070 0, R²=0.029 5; P=0.168), and the sunrise time (y=1.202 6x-0.491 1, R²=0.029 4; P=0.169), but the correlations were not significant. (2) The time between awakening of the crocodile lizard was significantly positively correlated with the first activity time (y=0.992 1x+0.115 1, R²=0.958 5; P<0.001). (3) Precipitation (with or without rain) had no effect on the awakening time and the first activity time of the crocodile lizard (awakening time: F=2.033, P=0.159; activity time: F=3.353, P=0.072).

In order to prognosis the biosecurity of PA2019NES which is with high yield of phenazines in agricultural exploitation, the real-time fluorescence quantitative PCR was applied to test the difference of transcriptional volume of 9 genes which were associated with biofilm, quorum sensing system and type Ⅵ secretory system, to reveal the transcriptional relationship between phzR and the above mentioned 9 genes, as well as its effect on the cells motility, especially the differeces between PA2016NX1 and PA2019NES, which was with multiple copies of phzR gene, were in biofilm and planktonic state, respectively. The results showed that, in the planktonic state, multiple copies phzR gene up-regulated the mRNA level of vgrG and algD genes (P<0.05), the mRNA level of pilA was down-regulated (P<0.05); however, the mRNA level of the other 6 genes was not significantly affected (P>0.05). In the biofilm state, the mRNA level of rhlI gene was up-regulated (P<0.05), but that of fimX and wspR genes was down-regulated (P<0.05) and that of the other 6 genes was not significantly affected (P>0.05). After 24 h culture, there was no significant difference in twitching ability between PA2016NX1 and PA2019NES (P>0.05), but the swimming, ability of PA2019NES was stronger than that of PA2016NX1 (P<0.05), however, the swarming ability of PA2019NES was weaker than that of PA2016NX1 (P<0.05). These results suggested that the power of conditional pathogenicity of PA2019NES may not be lower than that of PA2016NX1, hence, when PA2019NES was developed for agricultural use, the spread of live bacteria to the environment should be prevented.

High-throughput sequencing technology was used to analyze the evolution and diversity of microbial community structure in sequence batch reactors (R1, R2), the correlation between bacterial community and tomato sauce wastewater quality and the prediction of microbial enzymes. The results showed that there were significant differences in the level of phylum, class and genus. Proteobacteria and Bacteroidetes were the dominant phylum at the level of phylum. At class level, Betaproteobacteria, Alphaproteobacteria and Bacteroidia were the dominant bacteria. At the genus level, Zoogloea and Flavobacterium were the dominant genera. From the initial stage of particle formation to the stable stage, the abundances of Proteobacteria, Bacteroidetes, Betaproteobacteria, Alphaproteobacteria, Bacteroidia, Zoogloea and Flavobacterium in R1 and R2 were 1.75%, -7.20%, 35.49%, 0.12%, -15.23%, -3.11% and -5.23% respectively. The abundance of 1.78%, -2.00%, 33.11%, -0.54%, -14.80%, -2.87% and 6.13% showed little variation. But the differences in abundance was found in Alphaproteobacteria, Bacteroidia and Flavobacterium. Correlation analysis showed that Sphingobacteriia and Negativicutes had a significant negative correlation with NH₃-N and PO^3-₄-P, Flavobacteria had a significant negative correlation with COD. Gammaproteobacteria and Clostridia were significantly positively correlated with COD and NH₃-N, while Betaproteobacteria was significantly positively correlated with PO^3-₄-P. Proteobacteria has the effect of nitrogen removal, Bacteroidetes is related to the degradation of EPS, Acidobacteria has a positive effect on the initial coagulation of flocs sludge. Anaerolineae also exists in the sludge at the floc stage, and Anaerolineae is beneficial to the settlement of the floc sludge. Among them delta-9 desaturase (stearoyl-CoA dehydrogenase (ó-9 dehydrogenase) and transport system permease protein (system permease protein) are more abundant, and lactocepin (lactocerin), linoleoyl-CoA desaturase (sub oleoyl-CoA dehydrogenase) and ribosomal protein S6 modification protein (ribosomal protein S6 modification protein) changed most significantly, but microbial enzymes throughout the system maintained similar functions.

In order to improve Nanning's climate response capacity of social and economic development in the context of global climate change and to understand the characteristics of its climate change over the past 30 years, this paper researches and studies the climate change in Nanning in the past 30 years on the basis of Nanning's average temperature, precipitation and sunshine hours from 1991 to 2020, using linear regression method, moving average method and accumulative anomaly method. The results show: in the past 30 years, the average temperature of Nanning has shown a decreasing trend, representing a decrease of 0.007 1 ℃/a, and the average temperature of seasons except for spring has demonstrated a decreasing trend; the precipitation has shown a decreasing trend, representing a decrease of 0.887 mm/a, and the average precipitation of the seasons except for summer has demonstrated an increasing trend; the sunshine hours have shown an increasing trend, representing an increase of 6.300 1 h/a, and the average precipitation of seasons except for autumn has indicated an increasing trend. The analysis of Nanning's characteristics of climate change based on meteorological monitoring data obtained in the medium and longterm can effectively contribute to optimize and adjust its industrial structure, and the perfection of global climate change response measures.

Chengdu is the first site and demonstration area of “park city” in China. Scientific evaluation of its accessibility to comprehensive parks is of great significance for optimizing the spatial layout of parks and building a beautiful and livable park city in Chengdu. 23 comprehensive parks in the central city of Chengdu are selected as the research subjects.Space syntax and ArcGIS software are used to establish the segment model. By comprehensive analysis of the POI data and model checking, the spatial layout characteristicsand accessibility of the comprehensive parks in the downtown area of Chengdu are studied from the following three aspects, global accessibility, accessibility of local accessibility and awareness accessibility. The results show that the distribution of comprehensive parks in downtown Chengdu is not balanced, and the distribution of comprehensive parks in areas with high POI values is less, and the matching between comprehensive parks and urban residents' needs is weak. The urban road traffic network needs to be improved and the regional development is not coordinated enough. The overall level of global and local accessibility of parks is relatively high. Most of the parks are distributed in areas with high accessibility value, and some of the parks lack certain attraction themselves, and the perceived accessibility is mediocre. The factors that affect the accessibility of the park include the structure of the spatial road network, the spatial distribution of the park, the natural and human environment and so on. Based on the above analysis, some suggestion are put forward, such as making a more reasonable distribution of the parks, increasing the numbers of comprehensive parks, optimizing the urban traffic network; Adding more bus stations and subway stations; Integrating Chengdu's unique landscape culture with the historical culture, etc. to enhance the attractiveness of the landscape.