基于图式理论的高职学生英语演讲能力培养探索

演讲能力是演讲者的思辨能力、知识储备和语言交际能力的综合体现,基于图示理论,结合广东省高职高专实用英语口语大赛的演讲话题,提出要以策略图示知识调整学生学习策略,培养其思辨能力,加强图示知识输入,夯实其语言基础,扩大其专业知识储备。通过构建图示网络,促进学生思辨能力和语言交际能力的发展,最终提高学生的演讲能力。

基于单绿高亮硅基OLED显示屏的亮度调节电路设计

针对单绿高亮硅基OLED显示屏的特点,研究了其亮度调节电路,以满足高低温、宽范围亮度条件下的应用要求。选取2.4cm单绿高亮硅基OLED作为显示屏组件,设计了具有温度-亮度补偿功能的宽范围亮度调节电路,并优化了调亮曲线,以满足高低温下亮度一致性的应用要求。最后进行了相应的光电测试,验证其有效性。

基于Zynq的视频信号发生设备

为满足多种尺寸液晶显示模块测试要求,提出了一种基于Zynq-7000系列平台视频信号发生设备的设计。该片上系统利用Zynq片上微处理器和可编程逻辑在嵌入式系统开发中各自的优势,实现了包括多分辨率实时切换、定制化视频时序生成、带触摸功能人机交互界面等功能。

Bacterial infection triggers and complicates acute-on-chronic liver failure in patients with hepatitis B virus-decompensated cirrhosis: A retrospective cohort study

BACKGROUND Reports on bacterial infection(BI)in decompensated cirrhosis(DC)is mainly from alcoholic cirrhosis.The role of BI as a trigger or complication of acute-onchronic liver failure(ACLF)in patients with hepatitis B virus decompensated cirrhosis(HBV-DC)remains to be investigated.AIM To investigate the impact of BI on the outcomes of the patients with HBV-DC admitted into the hospital with or without ACLF.METHODS This retrospective study included patients with HBV-DC admitted to two tertiary centers in China.In-hospital overall survival,90-d transplant-free survival,5-year post-discharge survival,and cumulative incidence of ACLF were evaluated.Risk factors for death were analyzed considering liver transplantation as a competing event.RESULTS A total of 1281 hospitalized HBV-DC patients were included;284 had ACLF at admission.The overall prevalence of BI was 28.1%.The patients with BI had a significantly lower in-hospital survival and transplant-free 90-d survival than those without,in both the patients admitted with and without ACLF.The presence of BI significantly increased the risk of developing ACLF[subdistribution hazard ratio(sHR)=2.52,95%CI:1.75-3.61,P<0.001]in the patients without ACLF.In the patients discharged alive,those who had an episode of BI had a significantly lower 5-year transplant-free survival.BI was an independent risk factor for death in the patients admitted without ACLF(sHR=3.28,95%CI:1.93-5.57),while in ACLF admissions,the presence of pneumonia,but not other type of BI,independently increased the risk of death(sHR=1.87,95%CI:1.24-2.82).CONCLUSION BI triggers ACLF in patients with HBV-DC and significantly impairs short-term survival.HBV-DC patients should be monitored carefully for the development of BI,especially pneumonia,to avoid an adverse outcome.

Nutrient resorption strategies of three oak tree species in response to interannual climate variability

Background:Nutrient resorption is critical for plants toward balancing their nutritional requirements and adapting to environmental variabilities,which further impacts litter quality and nutrient cycling.However,the interannual variability of nutrient resorption under climate change remains unclear.Methods:We investigated the five-year nutrient resorption efficiencies(NuRE,%)of 14 elements in three deciduous oak tree species(Quercus aliena var.acuteserrata,Q.glandulifera,and Q.variabilis)in a warm-temperate forest of Central China and assessed their relationships with interannual climate and soil factors.Results:Nutrient resorption did not differ between species but varied significantly between different years.For each year,N,P,S,K,C,Mg,and Zn were preferentially resorbed in all of the oak species in contrast to Ca,Na,Mn,Ba,Al,Fe,Cu,which were to some extent discriminated.Among the 14 elements,the NuRE of C,N,P,S,Ca,and Mg was more sensitive to interannual climate variations in the three oak species.The carbon resorption efficiency was significantly increased during the driest year of the study(2014);N resorption efficiency was reduced with temperature;whereas N and P resorption efficiency initially decreased and then increased with precipitation.Moreover,the elements with higher NuREs typically had lower coefficient of variation(CV)in all three oak species.Conclusions:Different oak species exhibited analogous nutrient conservation strategies in response to annual climate variabilities,and interannual climate variations strongly impacted plant nutrient resorption.Deciduous plants may establish a tradeoff mechanism to rebalance somatic nutrients for regrowth at the end of the growing season.

Experimental study on the infrared precursor characteristics of gas-bearing coal failure under loading

The stress and gas pressure in deep coal seams are very high,and instability and failure rapidly and intensely occur.It is important to study the infrared precursor characteristics of gas-bearing coal instability and failure.In this paper,a self-developed stress-gas coupling failure infrared experimental system was used to analyse the infrared radiation temperature(IRT)and infrared thermal image precursor characteristics of gas-free coal and gas-bearing coal.The changes in the areas of the infrared temperature anomalous precursor regions and the effect of the gas on the infrared precursors were examined.The results show that high-temperature anomalous precursors arise mainly when the gas-free coal fails under loading,whereas the gas-bearing coal has high-temperature and low-temperature anomalous precursors.The area of the high-temperature anomalous precursor is approximately 30%–40%under gasbearing coal unstable failure,which is lower than the 60%–70%of the gas-free coal.The area of the low-temperature abnormal precursor is approximately 3%–6%,which is higher than the 1%–2%of the gas-free coal.With increasing gas pressure,the area of the high-temperature anomalous precursor gradually decreases,and the area of the low-temperature anomalous precursor gradually increases.The highand low-temperature anomalous precursors of gas-bearing coal are mainly caused by gas desorption,volume expansion,and thermal friction.The presence of gas inhibits the increase in IRT on the coal surface and increases the difficulty of infrared radiation(IR)monitoring and early warning for gas-bearing coal.

Electrically triggered dual-band tunable terahertz metamaterial band-pass filter based on Si_3N_4–VO_2–Si_3N_4 sandwich

We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transition of VO_2 film is induced by the Joule thermal effect of the top metal layer. The finite-integration-time-domain(FITD) method and finite element method(FEM) are used for numerical simulations. The sample is fabricated using a surface micromachining process,and characterized by a THz time-domain-spectrometer(TDS). When the bias current is 0.225 A, the intensity modulation depths at two central frequencies of 0.56 THz and 0.91 THz are about 81.7% and 81.3%, respectively. This novel design can achieve dynamically electric–thermo–optic modulation in the THz region, and has potential applications in the fields of THz communications, imaging, sensing, and astronomy exploration.

Viral vectors as a novel tool for clinical and neuropsychiatric research applications

Background A viral vector is a genetically modified vector produced by genetic engineering. As pathogenic genes in the virus are completely or largely eliminated, it is safe to be widely used in multidisciplinary research fields for expressing genes, such as neuroscience, metabolism, oncology and so on. Neuroscience and psychiatry are the most closely related disciplines in either basic research or clinical research, but the application of viral vectors in neuropsychiatry has not received much attention or not been widely accepted.Aim This article will focus on the application of viral vectors in basic and clinical neuropsychiatric research.Methods By using viral vectors, scientists can perform neurological labelling, gene expression regulation and physiological manipulation for investigating phenomenon from molecular mechanisms to behaviours. At the same time, to treat mental or neurological disorders, viral vectors can be designed for gene therapy, which alter gene expression levels or repair mutated genes in the brains of patients.Perspective Viral vectors play an important role in basic research and clinical applications. To further understand brain function and prevent mental and neurological diseases, we hypothesize that viral vectors could be used along with various advanced technologies, such as sequencing and high-throughput expression analysis in the neuroscience research field.

Suppression of grazing-induced instability in single degree-of-freedom impact oscillators

As a typical non-smooth bifurcation, grazing bifurcation can induce instability of elementary near-grazing impact periodic motion in impact oscillators. In this paper,the stability for near-grazing period-one impact motion to suppress grazing-induced instabilities is analyzed, based on which, a control strategy is proposed. The commonly-used leading order zero time discontinuity mapping is extended to a higher order one to aid the perturbation analysis of the characteristic equation. It is shown that the degenerate grazing bifurcation can eliminate the singular term in the characteristic equation, leading to bounded eigenvalues. Based on such a precondition, the bounded eigenvalues are further restricted inside the unit circle, and a continuous transition between non-impact and controlled impact motion is observed. One discrete feedback controller that changes the velocity of the oscillator based on the selected Poincar′e sections is adopted to demonstrate the control procedure.

Plasmon-induced transparency effect in hybrid terahertz metamaterials with active control and multi-dark modes

We numerically demonstrate a photo-excited plasmon-induced transparency(PIT)effect in hybrid terahertz(THz)metamaterials.The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wire and four metallic split-ring resonators(SRRs)whose gaps are filled with photosensitive semiconductor gallium arsenide(GaAs)patches.We simulate the PIT effect controlled by external infrared light intensity to change the conductivity of GaAs.In the absence of photo excitation,the conductivity of Ga As is 0,thus the SRR gaps are disconnected,and the PIT effect is not observed since the dark resonator(supported by the hybrid SRRs)cannot be stimulated.When the conductivity of GaAs is increased via photo excitation,the conductivity of Ga As can increase rapidly from 0 S/m to 1×10^(6)S/m and GaAs can connect the metal aluminum SRR gaps,and the dark resonator is excited through coupling with the bright resonator(supported by the cut wire),which leads to the PIT effect.Therefore,the PIT effect can be dynamically tuned between the on and off states by controlling the intensity of the external infrared light.We also discuss couplings between one bright mode(CW)and several dark modes(SRRs)with different sizes.The interference analytically described by the coupled Lorentz oscillator model elucidates the coupling mechanism between one bright mode and two dark modes.The phenomenon can be considered the result of linear superposition of the coupling between the bright mode and each dark mode.The proposed metamaterials are promising for application in the fields of THz communications,optical storage,optical display,and imaging.

Mitigation of Deane and Hamill phenomenon in gallium nitride high-voltage power supply for electric propulsion system application

The step-up resonant converters are widely adopted to provide high voltage in kV-level for electric propulsion system due to their high efficiency,low mass,modularisation,and high-power density.The bipolar Cockcroft-Walton voltage multiplier(BiCWVM)is a major circuit that steps up the voltage in the resonant converter.However,the diode nonlinearity in BiCWVM can introduce self-sustained quasi-periodic oscillations in the voltage and current waveforms,which is commonly known as the Deane and Hamill(DH)phenomenon.The oscillation can lead to higher magnetic loss and control failure,and it is more likely to present in the gallium nitride-based converter due to the highfrequency operation.The authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be implemented.To facilitate the investigation,the circuit before the BiCWVM in the converter is derived and modelled as a voltage source v_(m)and a series inductor L_(sy).Also,the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise-linear(PWL)model,with the simplified circuit and PWL model,the relationship between voltage and current under different operating conditions can be determined with ease.The relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH phenomenon.Finally,a hybrid-/full-silicon carbide(SiC)design is proposed to mitigate the DH phenomenon,which is verified experimentally for a 300-kHz,5-W,20-V/1.5-kV GaN-based step-up resonant converter.

非光滑准零刚度隔振器实验研究

理论上,与传统准零刚度隔振器(QZS)相比,含限位结构的准零刚度隔振器具有更低的位移传递率峰值和更宽的隔振频率范围.但是,目前还没有相关的实验研究证明这一理论结果的正确性.因此,为了研究含限位准零刚度隔振器在实际应用过程中的隔振特性,本文设计制作了相应的结构,并进行了动力学实验.首先,根据赫兹接触理论,建立了含限位结构的准零刚度隔振器(QZS-HCM)动力学模型.然后,对隔振器的结构进行设计和加工,制作了QZS-HCM系统,并对系统进行静力学实验来验证理论结果的正确性.接着,在简谐位移激励下,对QZS-HCM系统进行动力学测试,通过分析系统的位移传递率和时间历程来评价系统的隔振性能.同时,将QZS-HCM系统与传统QZS系统的动力学测试结果进行对比,表明QZS-HCM隔振器在大幅值位移激励下具有更低的位移响应峰值和更宽的隔振频带.

基于强化学习控制三连杆双足机器人实现节能周期步态

由于双足机器人有着强非线性和非光滑性的响应特性,为双足机器人设计高性能的步态控制器依旧是一个开放的研究领域.为了克服这些挑战,本文首先提出了一个包含躯干,并考虑碰撞与摩擦的三连杆双足机器人模型.随后,采用双延迟深度确定性策略梯度算法为该机器人设计了强化学习控制器.为了同时在下坡和上坡中实现节能周期步态,本文基于庞家莱截面法和幂函数构建了能为控制器提供学习指引的奖励函数.因此,所提出的控制器能够在不依赖于预先设计的参考轨迹或嵌入的不稳定周期步态的情况下,学会自适应输出精确的余弦力矩来实现控制目标.通过和神经网络比例微分控制器的对比研究表明,在不同的斜坡上,所提出的强化学习控制器均能实现精确、高效的周期步态,并具有较强的适应性和鲁棒性.

Investigation on the short-term outcome and prognostic impact of predisposition,and precipitants in inpatients with chronic liver disease from Chinese AcuTe on CHronic LIver FailurE(CATCH-LIFE)cohorts

Aim:The study aimed to investigate the short-term outcomes of hospitalized patients with chronic liver disease(CLDs)and assess the prognostic impact of predisposition and precipitants,which currently remains unclear.Methods:The study included 3970 hospitalized patients with CLDs from two prospective longitudinal multicenter studies(NCT02457637 and NCT03641872)conducted in highly endemic hepatitis B virus(HBV)areas.Competing risk analysis was used to evaluate the effect of predispositions,including the etiology and severity of CLDs and precipitants;on sequential 28,90,and 365-day liver transplantation(LT)-free mortality.Results:Among all enrolled patients,76.8%of adverse outcomes(including death and LT)within one year occurred within 90 days.Compared with alcoholic etiology,the association of HBV etiology with poorer outcomes was remarkably on the 28th day(hazard ratio[HR],1.81;95%confidence interval[CI],1.07-3.06;p=0.026);however,and dimin-ished or became insignificant at 90 days and 365 days.Cirrhosis increased the adjusted risk for 365-day(HR,1.50;CI,1.13-1.99;p=0.004)LT-free mortality when compared with noncirrhosis.In patients with cirrhosis,prior decompensation(PD)independently increased the adjusted risk of 365-day LT-free mortality by 1.25-fold(p=0.021);however,it did not increase the risk for 90-day mortality.Neither the category nor the number of precipitants influenced the adjusted risk of 28 or 90-day LT-free mortality.Conclusions:The 90-day outcome should be considered a significant endpoint for evaluating the short-term prognosis of hospitalized patients with CLD.Predisposing factors,other than etiology,mainly affected the delayed(365-day)outcome.Timely effective therapy for CLD etiology,especially antiviral treatments for HBV,and post-discharge long-term surveillance monitoring in cirrhotic patients undergoing PD are suggested to enhance disease management and reduce mortality.

Carbon sequestration and emissions mitigation in paddy fields based on the DNDC model: A review

The DeNitrification–DeComposition(DNDC)model is a process model with a series of carbon and nitrogen biogeochemistry in agro-ecosystems.It incorporates the driving factors of the ecological environment and aims to simulate the carbon and nitrogen cycle in the terrestrial ecosystem.Furthermore,the model can be applied effectively in a paddy ecosystem.Based on an investigation and literature review,this study summarized and analyzed the impact of agricultural practices such aswatermanagement,fertilizer application,and strawincorporation on greenhouse gas emissions and soil carbon storage.After years of improvement,the DNDC model can presently be used effectively to evaluate the carbon sequestration and emissions mitigation potential of various agricultural practices.However,the related details of scientific processes of agricultural management,such as biochar incorporation and plastic mulching in paddy fields,should be added or modified and combined with experimental cases of actual agricultural practices to complete the calibration of the model,provide theoretical support for its promotion,and establish a reliable method of evaluating carbon sequestration and emissions mitigation in paddy fields.

Coupled autotransformer and magneticcontrol soft-start method for super-largecapacity high-voltage motors

The large current generated by a direct start of the super-large-capacity high-voltage induction motor would have a huge impact on the power grid as well as the motor itself.Traditional soft starters have the shortcomings of discontinuous adjustment,voltage sags,sudden torque mutation,secondary current impact and high cost.To resolve this issue,the authors propose a novel coupled autotransformer and magnetic-control(CATMC)soft-start method.The structure of the new CATMC soft starter combines the functions of the autotransformer and magnetic control reactor via an innovative electric and magnetic circuit design.In this study,the authors analyse the magnetic circuit structure and working principles of the CATMC soft starter.Then,to validate its principle and performance,the authors conduct a simulation study using ANSYS software and design and test an 18 MW/10 kV CATMC soft starter prototype.The simulation results demonstrate that the CATMC soft starter effectively avoids secondary current impact and constrains the motor starting current to<2.5 times the rated current.The public connection point bus voltage also meets the voltage sag requirement of the IEEE standard and reduces the impact on the power grid.