Study of spatial and temporal evolution of Ar and F atoms in SF6/Ar microsecond pulsed discharge by optical emission spectroscopy

The study of sulfur hexafluoride(SF6) discharge is vital for its application in gas-insulated equipment. Direct current partial discharge(PD) may cause SF6 decomposition, and the decomposed products of SF6, such as F atoms, play a dominant role in the breakdown of insulation systems. In this study, the PD caused by metal protrusion defects is simulated by a needle-plate electrode using pulsed high voltage in SF6/Ar mixtures. The spatial and temporal characteristics of SF6/Ar plasma are analyzed by measuring the emission spectra of F and Ar atoms, which are important for understanding the characteristics of PD. The spatial resolved results show that both F and Ar atom spectral intensities increase first from the plate anode to the needle and then decrease under the conditions of a background pressure of400 Pa, peak voltage of-1000 V, frequency of 2 kHz, pulse width of 60 μs, and electrode gap of 5-9 mm. However, the distribution characteristics of F and Ar are significantly different. The temporal distribution results show that the spectral intensity of Ar decreasesfirst and then increases slowly, while the spectral intensity of F increases slowly for the duration of the pulsed discharge at the electrode gap of 5 mm and the pulse width of40-80 μs.

Spatio-temporal Evolution of Marine Fishery Industry Ecosystem Vulnerability in the Bohai Rim Region

The building of the ocean power strategy and the implementation of the blue agriculture plan urgently need to strengthen the sustainable development of marine fishery.Taking vulnerability as the starting point, this paper constructs the vulnerability index system of marine fishery industry ecosystem from the aspects of sensitivity and response capacity, and combines the entropy method with the Topsis to comprehensively analyze the spatio-temporal evolution characteristics of vulnerability of marine fishery industry ecosystem in the Bohai Rim Region from 2001 to 2015.The results show that: 1) In the time dimension, from 2001 to 2015, the vulnerability of the marine fishery industry ecosystem in the Bohai Rim Region shows a fluctuant and degressive trend;2) In the spatial dimension, the spatial distribution of the marine fishery industry ecosystem vulnerability in the Bohai Rim Region presents the gradient characteristics which shows high vulnerability in the east and low vulnerability in the west.According to the evolution track of the system’s vulnerability level, the vulnerability of the marine fishery industry ecosystem is divided into ‘declining’ and ‘stable’ types of evolutionary structures;3) The development of marine fishery in the Bohai Rim Region needs to be derived from the marine fishery’s ecological environment and the industrial development mode and structure, which can improve the marine environment remediation efforts, optimize the marine fishery industry structure, vigorously focus on pelagic fishery, and enhance the introduction of marine fishery’s science and technology talents, etc.Then, the marine fishery’s development in the Bohai Rim Region will be moving in the green, circular and sustainable direction.

Spatio-temporal evolution of ecologically-sustainable land use in China's Loess Plateau and detection of its influencing factors

Ecological land(Eco-land) is a basic resource for human beings to survive, and eco-land use is a strategy, a way to manage the land resource. So, ecologically-sustainable land use is essential for human beings to survive. This paper investigates the spatiotemporal characteristics and mechanisms of urban-rural eco-land using a new and innovative integration way based on eco-land change data in China's Loess Plateau(LP) prefecture level cities and explores factors of eco-land change. The spatial difference characteristic of eco-land among different level cities in the LP is that: small cities > big cities > middle cities. From 2009 to 2016, the eco-land in the LP from the perspective of urban-rural areas has changed significantly. Significant differences of urban-rural eco-land were identified among various urban growth types, and all the cities in the LP were further classified into four types based on eco-land change trend, with type A and B cities identified as the vital zone and major zone. Taking the eco-fragile region Loess Plateau(LP) as an example, our results demonstrated that the migrants to cities in LP could relieve ecological pressures and promote restoration of ecological vegetation. We have demonstrated that urbanization and the influence of government policy can be discerned through the quantification of the spatial-temporal change of eco-land and suggest that combining both urban and rural eco-land can support more effective land use decisions and provide theoretical basis for the practical application of urban planning, policy-making and sustainable development. What's more, governments should strive to population mobility and restore vegetation to sustain this fragile ecological environment.

Spatio-temporal Evolution and Driving Factors of the High-quality Development of Provincial Tourism in China

Accelerating the promotion of high-quality development of tourism(HQDT) is of great significance to the sustainable development of tourism. This paper defined the concept of HQDT, and then built an evaluation system for HQDT measurement to analyze the spatio-temporal evolution characteristics of China’s HQDT based on provincial panel data from 2010 to 2019, using Geodetector to explore the similarities and differences between driving factors of HQDT and tourism development scale(TDS). The results show that:1) Taking the development concepts of innovation, coordination, green, openness and sharing as the guidance, and considering the organic unity of quantity and quality, the evaluation index system of the HQDT consists of six dimensions of economic stability, innovation driving, coordination and linkage, green and sustainability, openness and cooperation, and sharing and harmony, which respectively represent the basis, momentum, means, orientation, direction and purpose of the HQDT;2) The level of China’s HQDT shows an upward trend, presenting the characteristics of eastern region > central region > western region > northeastern region in 2019. The regional differences in China’s HQDT show a downward trend, and the intra-regional differences have replaced the inter-regional differences as the main source of regional differences;3) China’s HQDT shows the characteristics of higher in the east and lower in the west along the Hu line, while the improvement speed of HQDT shows the characteristics of faster in the west and slower in the east, making the decline of east-west differentiation of China’s HQDT and the movement of the gravity center towards southwest;4) Both HQDT and TDS are obviously driven by tourism capital investment and regional consumption. In terms of differences, the HQDT is more driven by government guidance, innovation driving force, and opening up, while the main driving factors of TDS are more biased toward capital elements and hardware facilities, including informatization, tourism resource, traffic, and eco-environment.

Spatio-temporal Evolution Characteristics and Driving Mechanism of the New Infrastructure Construction Development Potential in China

With the advent of the era of big data and artificial intelligence, new infrastructure construction(NIC) has attracted the attention of many countries. The development of NIC provides an opportunity to bridge the digital divide and narrow the regional gap,providing continuous impetus to further promote economic development. Here, we considered 31 provincial-level administrative units in China(not including Hong Kong, Macao, and Taiwan of China due to data unavailable) and established comprehensive evaluation indicators for the development potential of NIC. Afterward, we used the entropy-weight TOPSIS model to determine the development potential of NIC and analyze its spatio-temporal evolution characteristics. Furthermore, the GeoDetector model was applied to explore the driving mechanism of the NIC development potential. The conclusions were as follows: (1) The Chinese NIC development potential is generally low. The eastern China was the region with the highest development potential year by year, while the development potential in the central China was found to be in an accelerating phase. (2) The evolution of the Chinese NIC development potential’s spatial pattern has been characterized by an inland extension and coastal agglomeration. Moreover, we identified a superior development zone, a rising development zone, an inferior development zone, and a declining development zone. (3) The scope of Chinese NIC development potential agglomeration areas has gradually expanded and its degree has gradually deepened. The range of high-value agglomeration in eastern area gradually expanded and its degree gradually deepened. (4) Investment in innovative talents appears as the core factor affecting the Chinese NIC development potential. Whether acting alone or synergistically with other factors, its promoting effect on Chinese NIC development potential is the strongest.

Characteristics of temporal evolution of particle density and electron temperature in helicon discharge

On the basis of considering electrochemical reactions and collision relations in detail, a direct numerical simulation model of a helicon plasma discharge with three-dimensional two-fluid equations was employed to study the characteristics of the temporal evolution of particle density and electron temperature. With the assumption of weak ionization, the Maxwell equations coupled with the plasma parameters were directly solved in the whole computational domain. All of the partial differential equations were solved by the finite element solver in COMSOL Multiphysics^(TM) with a fully coupled method. In this work, the numerical cases were calculated with an Ar working medium and a Shoji-type antenna. The numerical results indicate that there exist two distinct modes of temporal evolution of the electron and ground atom density, which can be explained by the ion pumping effect. The evolution of the electron temperature is controlled by two schemes: electromagnetic wave heating and particle collision cooling. The high RF power results in a high peak electron temperature while the high gas pressure leads to a low steady temperature. In addition, an OES experiment using nine Ar I lines was conducted using a modified CR model to verify the validity of the results by simulation, showing that the trends of temporal evolution of electron density and temperature are well consistent with the numerically simulated ones.

Simulation analysis on microscopic discharge characteristics of the bipolar corona of a floating conductor

A floating conductor exhibits a bipolar corona phenomenon with microscopic discharge characteristics that are still unclear.In this study,a plasma simulation model of the bipolar corona with 108 chemical reaction equations is established by combining hydrodynamics and plasma chemical reactions.The evolution characteristics of electrons,positive ions,negative ions and neutral particles,as well as the distribution characteristics of space charges are analyzed,and the evolutionary flow of microscopic particles is summarized.The results indicate that the positive end of the bipolar corona initiates discharge before the negative end,but the plasma chemistry at the negative end is more vigorous.The electron generation rate can reach 1240 mol(m^(3) s)^(-1),and the dissipation rate can reach 34 mol(m^(3) s)^(-1).The positive ion swarm is dominated by O_(4)^(+),and the maximum generation rate can reach 440 mol((m^(3) s)^(-1).The negative ion swarm is mainly O_(2) and O_(4).The O_(2) content is approximately 1.5-3 times that of O_(4),and the maximum reaction rate can reach 51 mol(m^(3) s)^(-1).The final destination of neutral particles is an accumulation in the form of O_(3) and NO,and the amount of O3 produced is approximately 4-6 times that of NO.The positive end of the bipolar corona is dominated by positive space charges,which continue to develop and spread outwards in the form of a pulse wave.The negative end exhibits a space charge distribution structure of concentrated positive charges and diffused negative charges.The validity of the microscopic simulation analysis is verified by the macroscopic discharge phenomenon.

The influence of grounded electrode positions on the evolution and characteristics of an atmospheric pressure argon plasma jet

An atmospheric pressure plasma jet(APPJ) in Ar with various grounded electrode arrangements is employed to investigate the effects of electrode arrangement on the characteristics of the APPJ.Electrical and optical methods are used to characterize the plasma properties.The discharge modes of the APPJ with respect to applied voltage are studied for grounded electrode positions of 10 mm,40 mm and 80 mm,respectively,and the main discharge and plasma parameters are investigated.It is shown that an increase in the distance between the grounded electrode and high-voltage electrode results in a change in the discharge modes and discharge parameters.The discharges transit from having two discharge modes,dielectric barrier discharge(DBD) and jet,to having three,corona,DBD and jet,with increase in the distance from the grounded to the high-voltage electrodes.The maximum length of the APPJ reaches 3.8 cm at an applied voltage of 8 kV.The discharge power and transferred charges and spectral line intensities for species in the APPJ are influenced by the positions of the grounded electrode,while there is no obvious difference in the values of the electron excited temperature(EET) for the three grounded electrode positions.

Time-resolved measurements of NO2 concentration in pulsed discharges by high-sensitivity cavity ring-down spectroscopy

To describe the complex kinetics of formation and destruction mechanism of nitrogen dioxide(NO_2), there is an increasing demand for real-time and in situ analysis of NO_2 in the discharge region. Pulsed cavity ring-down spectroscopy(CRDS) provides an excellent diagnostic approach. In the present paper, CRDS has been applied in situ for time evolution measurement of NO_2 concentration which is rarely investigated in gas discharges. In pulsed direct current discharge of NO_2/Ar mixture at a pressure of 500 Pa, a peak voltage of -1300 V and a frequency of 30 Hz, for higher initial NO_2 concentration(3.05?×?10^(14)cm^(-3), 8.88?×?10^(13)cm^(-3)),the NO_2 concentration sharply decreases at the beginning of the discharge afterglow and then becomes almost constant, and the pace of decline increases with pulse duration; however, for lower initial NO_2 concentration of 1.69?×?10^(13)cm^(-3), the NO_2 concentration also decreases at the beginning of the discharge afterglow for 200 ns and 1 μs pulse durations, while it slightly increases and then declines for 2 μs pulse duration. Thus, the removal of low-level NO_2 could not be promoted by a higher mean energy input.

Insights into spatio-temporal slow slip events offshore the Boso Peninsula in central Japan during 2011-2019 using GPS data

Using Global Positioning System(GPS)coordinate time series,we detect three transient slow slip events(SSEs)offshore the Boso Peninsula in central Japan during 2011-2019.To extract the tiny SSE signals obscured by the significant post-seismic deformation after the 2011 MW9.0 Tohoku earthquake,we develop a new GPS coordinate time series processing software to obtain these SSE-induced deformations from highnoise GPS data.In addition,we apply the principal component analysis-based inversion method(PCAIM)to get the spatio-temporal slip distribution of the three SSEs.The spatio-temporal evolutions of these slips reveal that the nucleation styles are different.Compared to the 2011 and 2018 SSEs,the 2013-2014 SSE displays faster slip spatio-temporal variation,deeper slip,shorter slip duration,minor seismic moment,and lower maximum slip rate.The 2018 SSE exhibits the most significant seismic moment,the maximum slip,and the maximum slip rate of these three SSEs.The spatio-temporal variations of the 2011 SSE are the most complex,containing two acceleration and deceleration phases.The slip zone expanded along the eastern side of the Boso Peninsula in the acceleration phase and shrank back in the deceleration phase.Furthermore,the recurrence interval of SSEs spans from 2.2 to 4 years during 2011-2019,suggesting that the recurrence interval might become shorter and non-periodic due to the enormous earthquake.After the 2013-2014 SSE,the recurrence interval of the SSE gradually returns to normal.Thus,we can infer that the SSE may occur every 4-7 years after the 2018 SSE if there is no large earthquake.

Path of Rural Sustainable Development Based on the Evolution and Interaction of Rural Functions:A Case Study of Chongqing Municipality,China

In order to investigate the evolutionary characteristics of rural functions and their interaction,37 districts and counties in Chongqing,China are used as research objects to measure the level of rural functions and analyze the interaction between rural functions using entropy value method and spatial autocorrelation method.The results show that from 2009 to 2019,the three main functions of production,living and ecology in Chongqing’s villages have been greatly enhanced,especially the production function.On the whole,the production and living functions are stronger in the western part,while the ecological functions are significant in the eastern and southern parts of Chongqing,with some differences in local spatial characteristics.This finding is consistent with the regional economic and social development of Chongqing.In addition,the interaction between rural functions is also evident.In general,production and living functions are mainly expressed in synergistic relationships.Ecological and production functions,including ecological and subsistence functions,mainly present a trade-off relationship.The interactions between rural functions also show clear spatial and temporal differences.In addition,different regions have different comparative advantage functions,and in this study,the counties of Chongqing are classified into four types.Policy makers are advised to adopt different measures according to the different types to promote sustainable rural development by coordinating the’production-living-ecological’functions of rural areas.This study reveals the spatio-temporal evolution of rural functions and the interaction between rural functions,which can provide theoretical support and practical reference for rural revitalisation and sustainable development.

Morphological evolution of a large sand bar in the Qiantang River Estuary of China since the 1960s

A large sand bar develops in the inner Qiantang River Estuary,China.It is a unique sedimentary system,elongating landwards by about 130 km.Based on long-term series of bathymetric data in each April,July,and November since the 1960s,this study investigated the morphological behavior of this bar under natural conditions and the influence of a large-scale river narrowing project(LRNP)implemented in the last decades.The results show that three timescales,namely the seasonal,interannual and decadal timescales,can be distinguished for the sand bar evolution.The first two are related to the seasonal and interannual variations of river discharge.During high discharge seasons or years,erosion took place at the upper reach and sedimentation at the lower reach.Consequently,the bar apex shifted seaward.The opposite development took place during low discharge seasons or years.The decadal timescale is related to LRNP.Due to the implementation of LRNP,the upper reach has experienced apparent erosion and currently a new equilibrium state has been reached;whereas the lower reach has been accumulated seriously and the accumulation still continues.Nonlinear relationships for how the bar apex location and elevation depend on the river discharge over various stages of LRNP have been established.Compared with the earlier stage of LRNP,the bar apex at present has shifted seaward by about 12 km and lowered by about 1 m.The sand bar movement has significant feedback on the hydrographic conditions along the estuary and has practical implications for coastal management.

Decomposition pathway and stabilization of ether-based electrolytes in the discharge process of Li-O_(2) battery

Ether-based electrolytes with relatively high stability are widely used in Li-O_(2) batteries (LOBs) with high energy density.However,they are still prone to be attacked by reactive oxygen species.Understanding the degradation chemistry of ether-based solvent induced by reactive oxygen species is significant importance toward selection of stable electrolytes for LOBs.Herein,we demonstrate that a great amount of H_(2) gas evolves on the Li anode during the long-term discharge process of LOBs,which is due to the electrolyte decomposition at the oxygen cathode.By coupling with in-situ and ex-situ characterization techniques,it is demonstrated that O_(2)^(-) induces the H-abstraction of tetraethylene glycol dimethyl ether(TEGDME) to produce a large amount of H_(2)O at cathode,and this H_(2)O migrates to Li anode and produce H_(2) gas.Based on the established experiments and spectra,a possible decomposition pathway of TEGDME caused by O_(2)^(-)at the discharge process is proposed.And moreover,three types of strategies are discussed to inhibit the decomposition of ether-based electrolytes,which should be highly important for the fundamental and technical advancement for LOBs.

Temporal and Spatial Evolution of Precursory Anomalies of the Wenchuan MS8.0 Earthquake and Their Mechanical Analysis

In order to study the spatiotemporal evolution of the precursory anomalies 10 years before the Wenchuan M_S8. 0 earthquake in 2008, the epicentral distance of the precursory anomalies is calculated by using the geometric center of the rupture region and the elliptical centerline of the aftershock region. The result shows, precursor anomalies gradually increased about 2 years before the Wenchuan earthquake. The ratio of abnormal items is greater than 25% in the near source area (about twice the source scale) and 17%-24% in the remote area (about 3-5 times the source scale). There are three different stages of spatiotemporal evolution of precursory anomalies. During the α stage (including α_1 and α_2,between 700 to 3000 days before the main earthquake),the anomalies are mainly distributed in the southwest and northwest area of the Wenchuan aftershocks area. It is shown that the precursors of the far source region and the near source area have the characteristics of outward expansion. During the β stage (between 300 to 700 days before the main earthquake), the anomalies are distributed in the southwest and northern region of the aftershock region, showing a large range of anomalies. During the γ stage (including γ_1 and γ_2, 300 days before the main earthquake),the range of anomaly distribution is wide,and the anomalies are distributed in the southwest and northeast of the aftershock area. The anomalies converged to epicenter (γ_1) in the far source region and expand outwards (γ_2) in the near source region. Results of the experimental study and mechanical analysis of earthquake preparation process indicate that the three-stage characteristics of precursory anomalies in the process of earthquake preparation may be controlled by the seismogenic body,which is a form of expression in the process of earthquake preparation and a universal featureduring the earthquake preparation process,which has a certain guiding role in earthquake prediction.

GIL支柱绝缘子嵌件-环氧界面缺陷演化过程与放电脆裂机制

交流GIS/GIL支柱绝缘子在生产、运行过程中其金属嵌件-环氧界面容易引入气隙缺陷,被认为是导致支柱绝缘子炸裂击穿故障的重要诱因。通过设计带有气隙缺陷的支柱绝缘子并搭建炸裂模拟实验平台,研究了绝缘子嵌件-环氧界面缺陷演化与炸裂过程。基于实验研究结果,将支柱绝缘子炸裂过程分为3个特征阶段:裂纹产生与扩展阶段、断裂阶段、炸裂阶段,气隙缺陷引发的局部放电会诱导裂纹的产生与劣化扩展,导致绝缘子在极短的时间内快速断裂并在多次高能电弧冲击下炸裂,呈现脆性断裂的特征。同时,通过实验分析了影响支柱绝缘子炸裂的关键因素,直流电压下绝缘子的炸裂概率比交流电压低10%~20%。进一步构建了电-机械耦合作用下的裂纹扩展相场仿真模型,分析了支柱绝缘子不同炸裂阶段的主导机制。在裂纹的产生与扩展阶段,电势能起到主要作用;在断裂阶段,电势能的作用逐渐减弱,机械势能逐渐增大并起到主导作用,当机械势能达到材料应力临界点时,绝缘子发生脆性炸裂。该研究成果初步揭示了支柱绝缘子气隙缺陷引发的放电脆裂机制,为支柱绝缘子的故障分析及优化设计提供理论基础。

基于Cesium的水利工程三维可视化平台开发研究

水利行业正以前所未有的态势推进数字孪生,水利工程三维可视化作为智慧水利的基础,亟需解决水利工程三维可视化还无法达到专业软件的可视化要求。结合Cesium、Vue、Springboot等技术搭建了水利工程三维可视化平台,研究实现了多源数据融合、闸门动态泄水、洪水淹没等三维可视化关键应用技术,为后续实现数字孪生的可视化奠定基础。

Spatio-temporal evolution of Beijing 2003 SARS epidemic

Studying spatio-temporal evolution of epidemics can uncover important aspects of interaction among people, infectious diseases, and the environment, providing useful insights and modeling support to facilitate public health response and possibly prevention measures. This paper presents an empirical spatio-temporal analysis of epidemiological data concerning 2321 SARS-infected patients in Beijing in 2003. We mapped the SARS morbidity data with the spatial data resolution at the level of street and township. Two smoothing methods, Bayesian adjustment and spatial smoothing, were applied to identify the spatial risks and spatial transmission trends. Furthermore, we explored various spatial patterns and spatio-temporal evolution of Beijing 2003 SARS epidemic using spatial statistics such as Moran’s I and LISA. Part of this study is targeted at evaluating the effectiveness of public health control measures implemented during the SARS epidemic. The main findings are as follows. (1) The diffusion speed of SARS in the northwest-southeast direction is weaker than that in northeast-southwest direction. (2) SARS’s spread risk is positively spatially associated and the strength of this spatial association has experienced changes from weak to strong and then back to weak during the lifetime of the Beijing SARS epidemic. (3) Two spatial clusters of disease cases are identified: one in the city center and the other in the eastern suburban area. These two clusters followed different evolutionary paths but interacted with each other as well. (4) Although the government missed the opportunity to contain the early outbreak of SARS in March 2003, the response strategies implemented after the mid of April were effective. These response measures not only controlled the growth of the disease cases, but also mitigated the spatial diffusion.

Spatio-temporal evolution of the optical field on a hohlraum wall at the rising edge of a flat-topped pulse

Considering the time delay in different hohlraum wall positions caused by oblique incidence,the spatio-temporal optical field distribution characteristics of a hohlraum wall,especially during the rising edge of a flat-topped pulse,is simulated by a fast Fourier transform method together with chromatography.Results demonstrate that beam propagation along the hohlraum wall is a push-broom process with complex dynamic spatial–temporal evolution.In the first few picoseconds,the optical intensity of the front position increases rapidly,while that of the rear position is relatively weak.The ratio R of the optical intensity during the rising edge is smaller than that of the steady state.R gradually increases and finally tends to the value of the steady state with time.Calculation also shows that,with shorter total width of the rising edge,R of the optical field decreases and the difference compared to the steady state becomes larger.The evolution is more severe with smaller angle of inclination.

三峡工程运用后长江中游河床调整沿程变化特点

三峡工程运行后,坝下游河道发生持续冲刷。本文研究了长江中游(955 km)不同河段沿程演变差异及其原因。总体而言,河床形态调整幅度自上而下减弱,这是因为在河床持续冲刷过程中,水流含沙量沿程恢复,故越往下游冲刷相对缓慢。平面形态方面,长江中游岸线崩退及洲滩变形的强度均呈沿程减弱趋势,且在荆江河段最为显著。断面形态方面,河床冲深幅度在宜枝下段>荆江河段>宜枝上段>城汉河段>汉湖河段。理论上距离三峡工程最近的河段冲刷应最为剧烈,但由于宜枝上段床沙粗化显著,限制了冲刷的进一步发展。过流能力方面,宜枝河段由于距洞庭湖较远,并未受到入汇顶托作用,故其平滩流量的调整基本由进口水沙条件控制,并随着河床冲深下切而增大;对于荆江、城汉和汉湖河段,河床冲刷虽显著,但支流或湖泊的入汇顶托对平滩流量产生的影响大于前者,故平滩流量总体随上下游水位差同步波动。

大气压交流正弦电压辅助脉冲放电过程与特性研究

为研究脉冲电压处于交流正弦电压不同相位时对等离子体射流特性和放电过程的影响,利用双电极耦合介质阻挡放电装置产生大气压脉冲放电等离子体射流,通过放电空间分布在脉冲电压阶段的变化,分析放电图像强度的时间演化和等离子体子弹速度的空间分布,证实了等离子体射流是以等离子体子弹形式在放电空间传播的。研究表明,脉冲电压极性与交流正弦电压极性相同或相反都会对等离子体子弹的产生和传播展现出抑制或加强效果。