Prediction of coal structure using particle size characteristics of coalbed methane well cuttings

Severely deformed coal seams barely deliver satisfactory gas production. This research was undertaken to develop a new method to predict the positions of deformed coals for a horizontal CBM well. Firstly, the drilling cuttings of different structure coals were collected from a coal mine and compared. In light of the varying cuttings characteristics for different structure coals, the coal structure of the horizontally drilled coal seam was predicted. And the feasibility of this prediction method was discussed. The result shows that exogenetic fractures have an important influence on the deformation of coal seams. The hardness coefficient of coal decreases with the deformation degree in the order of primary structural, cataclastic and fragmented coal. And the expanding-ratio of gas drainage holes and the average particle size of cuttings increase with the increase of the deformation degree. The particle size distribution of coal cuttings for the three types of coals is distinctive from each other. Based on the particle size distribution of cuttings from X-2 well in a coal seam, six sections of fragmented coal which are unsuitable for perforating are predicted. This method may benefit the optimization of perforation and fracturing of a horizontal CBM well in the study area.

PARTICLE SIZE AND MICROSTRUCTURE OF Ni NANOPOWDERS PREPARED BY ANODIC ARC PLASMA

Pure Ni nanopowders were successfully prepared by the method of anodic arc disch arged plasma with homemade experimental apparatus. The particle size, mircostruc ture and morphology of the particles by this process were characterized via X-ra y powder diffraction (XRD), transmission electron microscopy (TEM) and the corre sponding selected area electron diffraction (SAED); The specific surface area an d pore parameters were investigated by multi-point full analysis of nitrogen ads orption-desorption isotherms at 77K by Brunauer- Emmett-Teller (BET) surface are a analyzer; The chemical composition were determined by X-ray energy dispersive spectrometry (XEDS) equipped in SEM and element analyze instrument. The experime nt results indicate that the samples by this method with high purity,the crystal structure of the particles is as same as the bulk material, is fcc structure, w ith average particle sizes about 47nm, ranging from 20 to 70nm, and distributed uniformly in spherical chain shapes, the specific surface areavis 14.23m2/g, po re volume of pore is 0.09cm3/g and average pore diameter is 23nm.

Creating burdock polysaccharide-oleanolic acid-ursolic acid nanoparticles to deliver enhanced anti-inflammatory effects:fabrication,structural characterization and property evaluation

This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules.

Comparison of Two Methods to Assess the Size Structure of Phytoplankton Community Assemblages, in Liaodong Bay, China

Liaodong Bay is one of the largest semi-enclosed bays located in Bohai Sea,in northeast China.It is an important feeding and spawning place,even wintering and breeding migration base for many marine organisms.The size structure of phytoplankton communities is a key feature of marine ecosystems and can be used as an indicator for algae disaster,but the methods to evalute is still challenging.Here,we compared the size-fractionated chlorophyll-a method with a high-throughout sequencing method in an evaluation of the size structure of phytoplankton assemblages in Liaodong Bay,China,in 2014.The proportion of picophytoplankton was estimated at just 19%according to the results based on size-fractionated chlorophyll-a,which likely represents a severe underestimation.The sequencing method confirmed that many kinds of phytoplankton species appeared in more than one size-fractionated filter membrane,with some even dominating where the filter membrane pore size was greater than the individual phytoplankton size.According to the sequencing method,the phytoplankton assemblages in Liaodong Bay were dominated by picophytoplankton(average proportion=44%),followed by the nanophytoplankton(average 32%),a composition that is more consistent with other studies.The sequencing method provides a more robust way to assess the size structure and taxonomic diversity of marine phytoplankton communities.

Effect of Spherical Particle Size on the Electrochemical Properties of Lithium Iron Phosphate

The effect of spherical particle size on the surface morphology, electrochemical property and processability of lithium iron phosphate was systematically studied. Spherical lithium iron phosphate with different particle size distributions controlled with ball time of precursor slurry was prepared by spray drying method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), charge and discharge measurements and EIS. The electrochemical performances of the sample materials were measured by coin cells and 14500 batteries. XRD shows that the spherical lithium iron phosphate with different particle sizes all have good crystal structure due to the perfect mixing of the raw materials and rapid drying. The lithium iron phosphate microsphere with different particle sizes self-assembled with submicron primary particles has a core-shell structure. The longer ball time the precursors are, the smaller the active material particles are prepared. The electrode material with 6 h ball time of precursor slurry has the best physical properties and the processability. The composite has a uniform particle size and higher tap density of 1.46 g/cm3, which delivers a discharge capacity of 167.6 mAh/g at a discharge rate of 0.5 C. The results were confirmed by the 14 500 mA h cylindrical batteries, which delivers a discharge capacity of 579 mAh at 0.5 C. And low-temperature performance with capacity of 458.5 mA h at -20 °C under a discharge rate of 0.5 C is the 79.2% of the same discharge rate at 25 °C. Otherwise, the 14500 batteries also exhibit excellent cycling performance and the capacity maintains 93% after 2 000 cycles.

Preparation and particle size characterization of Cu nanoparticles prepared by anodic arc plasma

Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction （XRD）, BET equation, transmission electron microscopy （TEM）, and the corresponding selected area electron diffraction （SAED）. The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m^2/g, the particle size distribution is 30 to 90 nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

Effects of particle size and content of RDX on burning stability of RDXbased propellants

Particle size and content of RDX are the two main factors that affect the burning stability of RDX-based propellants. However, these effects and the corresponding mechanisms are still controversial. In this work, we investigated the physicochemical processes during burning and the corresponding mechanisms through the technologies of structure compactness analysis on the base of voidage measurement and theoretical interfacial area estimation, apparent burning rate measurement using closed vessel(CV)and extinguished burning surface characterization relying on interrupted closed vessel(ICV) and scanning electron microscope(SEM). The results indicate that the voidage increased with the increase of RDX content and particle size due to the increasing interfacial area and increasing interface gap size,respectively. The apparent burning rate increased with the increase of RDX particle size because of the decreasing RDX specific surface area on the burning surface, which could decrease the heat absorbing rates of the melting and evaporation processes of RDX in the condensed phase. Similarly, the apparent burning rate decreased with the increase of RDX content at pressures lower than around 55 MPa due to the increasing RDX specific surface area. Whereas, an opposite trend could be observed at pressures higher than around 55 MPa, which was attributed to the increasing heat feedback from the gas phase as the result of the increasing propellant energy. For propellants containing very coarse RDX particles, such as 97.8 and 199.4 μm average size, the apparent burning rate increased stably with a flat extinguished surface at pressures lower than around 30 MPa, while increased sharply above around 30 MPa with the extinguished surface becoming more and more rugged as the pressure increased. In addition, the turning degree of u-p curve increased with the increase of coarse RDX content and particle size, and could be reduced by improving the structure compactness.

Occurrence and influence of residual gas released by crush methods on pore structure in Longmaxi shale in Yangtze Plate, Southern China

The composition of gas released under vacuum by crushing from the gas shale of Longmaxi Formation in Upper Yangtze Plate,Southern China was systematically investigated in this study.The effect of residual gas release on pore structures was checked using low-pressure nitrogen adsorption techniques.The influence of particle size on the determination of pore structure characteristics was considered.Using the Frenkel-Halsey-Hill method from low-pressure nitrogen adsorption data,the fractal dimensions were identified at relative pressures of 0‒0.5 and 0.5‒1 as D1 and D2,respectively,and the evolution of fractal features related to gas release was also discussed.The results showed that a variety component of residual gas was released from all shale samples,containing hydrocarbon gas of CH4(29.58%‒92.53%),C2H6(0.97%‒2.89%),C3H8(0.01%‒0.65%),and also some non-hydrocarbon gas such as CO2(3.54%‒67.09%)and N2(1.88%‒8.07%).The total yield of residual gas was in a range from 6.1μL/g to 17.0μL/g related to rock weight.The geochemical and mineralogical analysis suggested that the residual gas yield was positively correlated with quartz(R^2=0.5480)content.The residual gas released shale sample has a higher surface area of 17.20‒25.03 m^2/g and the nitrogen adsorption capacity in a range of 27.32‒40.86 ml/g that is relatively higher than the original samples(with 9.22‒16.30 m^2/g and 10.84‒17.55 ml/g).Clearer hysteresis loop was observed for the original shale sample in nitrogen adsorption-desorption isotherms than residual gas released sample.Pore structure analysis showed that the proportions of micro-,meso-and macropores were changed as micropores decreased while meso-and macropores increased.The fractal dimensions D1 were in range from 2.5466 to 2.6117 and D2 from 2.6998 to 2.7119 for the residual gas released shale,which is smaller than the original shale.This factor may indicate that the pore in residual gas released shale was more homogeneous than the original shale.The results indicated that both residual gas and their pore space have few contributions to shale gas production and effective reservoir evaluation.The larger fragments samples of granular rather than powdery smaller than 60 mesh fraction of shale seem to be better for performing effective pore structure analysis to the Longmaxi shale.

Preparation and characterization of colloidal dispersions of graphene-like structures from different ranks of coals

This paper focuses on preparation of colloidal solution of graphene-like structures from different ranks of coals: brown coal,bituminous coal,low-volatile bituminous coal,anthracite. It was found that brown coal thermo-oxidative destruction leads to formation of small d = 32 nm( V = 17%) and large d = 122 nm( V = 11%) fractions of nanoparticles. The thermo-oxidative destruction of bituminous coal leads to formation of nanoparticles d = 50 nm( V = 5.2%) and d = 164 nm( V = 16%). Thermooxidative destruction of low-volatile bituminous coal and anthracite leads to formation of nanoparticles,predominantly,d = 122-190 nm. Carbon nanostructures obtained from coal are negatively charged at pH= 2-12. Colloidal solution of carbon nanostructures at dispersed phase concentration 0. 01 mg/mL is stable for 1 month. Electron diffraction patterns and X-ray analysis of carbon nanostructures showed that nanostructure from brown coal is amorphous and nanostructure from anthracite is crystalline. Results of coal macromolecules modeling and graphene-like structures obtained from them are presented.

东江三角洲河网浮游植物粒径特征研究

于2021-2022年春夏秋冬四个季节对东江三角洲河网的浮游植物叶绿素a浓度及粒径结构(小型Micro,微型Nano,微微型Pico)进行了季节性调查研究。结果显示夏季浮游植物叶绿素a浓度均值明显高于其他季节。粒径组成结果显示,小型和微型浮游植物叶绿素a浓度占比较高,二者浓度占比之和的年平均值为97.25%。粒径结构的季节特征显示,Micro浓度占比季节差异显著,Nano和Pico浓度占比季节差异不显著。空间特征显示,靠近珠江口的站位一般呈现出Nano浓度占比大于Micro浓度占比的规律。冗余分析(Redundancy analysis,RDA)显示,Micro浓度占比与水温、pH和河宽呈正相关关系,Nano浓度占比与透明度呈正相关关系。聚类分析结果显示,调查站位被明显分成了上游和下游两大类群,两大类群间浮游植物粒径组成差异显著,其中两类群中Micro、Nano叶绿素a浓度占比差异显著,Pico叶绿素a浓度占比差异极显著。另外,研究发现,两类群间差异显著的物理因子主要为盐度,差异显著的化学因子主要为pH和TP。结合RDA分析结果,推测盐度和pH是影响东江三角洲浮游植物粒径组成空间分布的关键环境因子。

春季桑沟湾硅藻群落结构对硅酸盐加富的响应研究

2021年5月,在水温13.83~16.96℃下,用现场陆基围隔实验方法研究添加硅酸盐对山东荣成桑沟湾养殖海区浮游植物丰度(以叶绿素a浓度表征)、粒径结构以及群落结构的影响。体积为100 L的直筒型透明聚乙烯袋围隔而成的实验单元,设置3个处理组,每组三个平行:自然海水组1.41μmol/L SiO_(3)-Si(对照组);低浓度组20.00μmol/L SiO_(3)-Si(LS组);高浓度组100.00μmol/L SiO_(3)-Si(HS组);取桑沟湾近岸表层海水70 L,经200μm筛绢过滤后注入实验单元,每个实验单元中均配置2 W的小型抽水泵,保持海水始终处于混匀状态,不与外部水体交换,添加的硅酸盐为分析纯九水硅酸钠,并固定在长200 cm、宽160 cm、高120 cm,容积约3 800 L的陆基围隔中,实验持续时间7 d。结果显示:(1)添加硅酸盐可提高浮游植物叶绿素a浓度,LS组和HS组叶绿素a浓度分别是对照组的1.95倍和1.94倍,主要是小型浮游植物和微型浮游植物的叶绿素a浓度显著提高;(2)硅藻是浮游植物群落结构的优势种,占物种丰富度的77.27%,硅藻细胞丰度变化范围为0.96×103~1.62×103cells/L,LS组和HS组的硅藻细胞丰度比对照组分别增加了53.53%和69.77%;(3)添加硅酸盐显著促进了小环藻(Cyclotella)、小新月菱形藻(Nitzschia closterium f.minutissima)、圆海链藻(Thalassiosira rotula)等生长(P<0.05),其中小新月菱形藻的藻细胞丰度增加显著,比对照组增加了181.69%;(4)添加硅酸盐对浮游植物多样性和均匀度无显著影响,但可显著增加浮游植物群落结构的物种丰富度(P<0.05)。本结果将为后续探索养殖水域关键时段硅元素补充策略、研发浮游植物初级生产力提升技术进而提高贝类养殖容量的可能性提供基础数据和有价值的线索。

粒径计算方法对细观混凝土数值建模的影响

采用最小包围盒(MBB)法确定骨料粒径,并与采用等体积球(EVS)法计算的骨料粒径进行比较,分析了这2种粒径计算方法对细观混凝土内部结构的影响.结果表明:采用MBB法计算的骨料粒径与室内试验采用筛分法确定的骨料粒径更为接近;与MBB法相比,EVS法低估了球状、片状和盘状骨料的粒径,且被低估的骨料占比由大到小依次为球状、片状和盘状,EVS法高估了棒状骨料的粒径;粒径计算方法对细观混凝土内部结构的影响因骨料形状类型不同而呈现一定差异性.

GPM DPR产品在东北地区两类降水过程中的应用评估

全球降雨观测计划(Global Precipitation Measurement,GPM)卫星自2014年2月发射以来,为高纬度地区的降水三维观测提供了基础,其搭载的双频星载测雨雷达(Double-frequency Precipitation Radar,DPR)反演的4种降水产品可以为中高纬度地区降水研究提供参考。本文利用GPM DPR提供的4种降水产品(Ka_HS、Ka_MS、Ku_NS和DPR_MS),对东北地区两次不同类型降水天气过程的降水结构特征进行分析,探究其宏微观特征的差异,并对GPM DPR的4种产品性能差异进行对比。结果表明:东北地区春季层状云降水的分布范围很广,大部分降水强度低于4.00 mm·h^(-1),且云系发展较为平缓,而夏季混合性降水的强度分布极其不均,且垂直方向发展较为旺盛,回波顶高度可达12 km。对比4种降水产品发现,Ka_MS降水强度、回波顶高度和降水类型划分都具有明显缺陷;Ka_HS可探测到更多的弱降水样本,但在雨强较大时也会出现严重衰减;Ku_NS能够提供较为可靠的回波顶高度和降水类型划分;DPR_MS产品具有独立表现,其中小于0.50 mm·h^(-1)的弱降水与Ka_HS的相关性较好,大于1.00 mm·h^(-1)的降水与Ku_NS有较好的一致性,此外,DPR_MS对降水和雨滴谱的垂直结构表征最合理。

Cu^(2+)污染原状黄土的物化及结构特性

为制定环境保护和土壤污染防治和修复策略,以及为污染场地工程建设提供理论支撑,该文研究了Cu^(2+)对原状黄土物化特性及结构特性的影响。通过制备不同掺量的Cu^(2+)污染黄土试样,进行了粒径分布、CaCO_(3)含量和pH值的测定。利用扫描电镜和激光粒度仪获得试样的SEM图像和粉粒各粒径含量,并借助分形理论深入分析了Cu^(2+)对原状黄土微观结构的影响机理。对Cu^(2+)污染的原状黄土试样进行了压缩试验,并对试样的综合结构势进行了分析。结果表明,随着Cu^(2+)掺量的增大,黏粒含量表现为先增后减,再增再减的趋势,粉粒含量则表现为先减后增,再减再增,砂粒含量保持不变;CaCO_(3)的含量呈线性减小;pH值先迅速减小,后保持不变;污染黄土试样的综合结构势先增大后减小,之后再增大再减小。总体而言,重金属Cu^(2+)的掺入,导致土壤pH值降低,主要胶结物质碳酸钙被溶解,而又因黏粒之间的静电引力和范德华力,黏粒聚集体的形态和成分发生变化,从而影响了土体的密实度和结构强度。

注水开发中悬浮物粒径与储层孔隙结构匹配关系

为了完善注水开发中悬浮物粒径中值指标制定方法,以南海西部涠洲油田群为例,在统计大量数据的基础上,分析主力生产层位岩石孔隙结构参数与渗透率之间的关系(R_(c)-K);通过室内岩心驱替实验对油田群原有注水指标进行优化,得出渗透率与粒径中值的关系(K-d);关联R_(c)-K方程以及K-d关系后,得到不同岩心级别下注入水悬浮物粒径中值与喉道直径的匹配关系(d/2Rc)。结果表明:以渗透率保留率80%为标准,K=(10~50)×10^(-3)μm^(2)时颗粒粒径中值与喉道直径比d/2R_(c)=1/6;K=(50~100)×10^(-3)μm^(2)时d/2R_(c)=1/5;K=(100~300)×10^(-3)μm^(2)时d/2R_(c)=1/5。

粒度对熔剂性球团冶金性能及矿相结构的影响

为提高熔剂性球团质量,解析不同粒度条件下球团性能的变化规律,本文以唐钢新区带式焙烧机球团生产线为研究对象,通过投笼造球试验和冶金性能检测等方式,分别对8.0~10.0、10.0~12.5、12.5~16.0、16.0~20.0 mm 4种粒度条件下球团冶金性能和矿相结构进行研究。结果表明:随着熔剂性球团粒度的逐渐提高,球团抗压强度从1767 N/P提高至3606 N/P,1 h还原度从78.5%降低至47.8%,还原膨胀指数略有降低,整体维持在12%以下,低温还原粉化指数(>6.3 mm)从87.8%降低至66.5%,低温还原粉化指数(>3.15 mm)从95%降低至87.2%,低温还原粉化指数(<0.5 mm)变化幅度较小,约为4%;随着熔剂性球团粒度的逐渐提高,气孔率降低,从38.93%降低为31.4%,液相率略有降低,固相比例显著提高,从41.05%提高至58.41%,致密度提高但液相率降低可能使得原本存在的链接状态失去效果,侧面减弱了熔剂性球团的低温还原粉化性能。因此,在熔剂性球团生产过程中应控制合适的球团粒度,改善熔剂性球团性能和微观结构,以便有利于高炉提产顺行。

Literature overview of basic characteristics and flotation laws of flocs

Flocculation flotation is the most efficient method for recovering fine-grained minerals,and its essence lies in flotation and recovery of flocs.Fundamental physical characteristics of flocs are mainly determined by their apparent particle size and structure(density and morphology).Substantial researches have been conducted regarding the effect of floc characteristics on particle settling and water treatment.However,the influence of floc characteristics on flotation has not been widely studied.Based on the floc formation and flocculation flotation,this study reviews the fundamental physical characteristics of flocs from the perspectives of floc particle size and structure,summarizing the interaction between floc particle size and structure.Moreover,it thoroughly discusses the effect of floc particle size and structure on floc floatability,further revealing the influence of floc characteristics on bubble collision and adhesion and elucidating the mechanisms of interaction between flocs and bubbles.Thus,it is observed that floc particle size is not the only factor influencing flocculation flotation.Within the appropriate apparent particle size range,flocs with a compact structure exhibit higher efficiency in bubble collision and adhesion during flotation,thereby resulting in enhanced flotation performance.This study aims to provide a reference for flocculation flotation,targeting the development of more efficient and refined flocculation flotation processes in the future.

基于有限质点法和代理模型的加筋箱梁结构筋板尺寸优化

为解决加筋箱梁结构筋板尺寸的优化问题,文中先用无需构建刚度矩阵直接求解几何非线性问题的有限质点法对结构进行屈曲分析,再由基于泛克里金代理模型和多岛遗传算法相结合的全局搜索策略优化筋板的尺寸,从而在保证分析精度的条件下节省数值计算的时间,最后以单向受弯箱梁节段为例对其屈曲分析和尺寸优化设计。通过与原模型的比较,在优化过程收敛性好、时间成本低的情况下满足了提升承载性能的目标,验证了所提出的优化方法的可靠性。

神华煤直接液化残渣理化特性与分子结构特征研究

煤液化残渣制备高端炭材料是目前煤直接液化技术领域研究的热点,该过程实现的关键在于煤液化残渣的深度脱灰,而深度脱灰工艺技术开发需要对液化残渣理化特性与分子结构有深入的认识。以神华煤液化残渣为研究对象,借助TG-DTG探究了液化残渣的失重特性;借助激光粒度仪和透射电镜(TEM)分别研究了液化残渣在洗油和四氢呋喃两种溶剂中的粒度分布特性和颗粒形貌特征;在正负离子(±ESI)和正离子大气压光电离(+APPI)模式下,利用傅里叶变换离子回旋共振质谱仪(FT-ICR MS)对液化残渣的分子结构组成进行了鉴别。研究结果表明:液化残渣的主要失重温区为300℃~600℃,466℃时失重速率最大,此时的活性最高;液化残渣在洗油或四氢呋喃中的粒度呈现百纳米级正态分布,残渣在洗油中粒度分布更为集中且粒径更小;液化残渣中含丰富的N1、N2类含氮杂环以及O1、O2、O3、CH类含氧多环的芳香分子构型。

粒度对煤吸附/解吸一氧化碳的影响

CO常作为有效标志气体用于煤自燃预报预警,采空区自燃封闭后CO迅速降低甚至消失的致因尚不明晰,影响煤自燃程度的精准判定。为深入研究煤体对CO气体的吸附/解吸特征,采用压汞和液态氮气吸附实验,测试研究煤样孔隙结构;利用自主研发的气体吸附/解吸装置,在303.15~333.15 K与0.15~0.50 MPa条件下,探索不同粒度煤样对CO气体吸附/解吸特性的影响,并深入分析CO的吸附速率和解吸滞后效应。结果表明:灵新矿不黏煤煤样的孔容以大孔和过渡孔为主,分别占33.02%和38.26%;孔比表面积以微孔和过渡孔为主,共占97.73%。粒径减小,微孔孔容与孔比表面积所占比例增加,过渡孔和中孔的孔容与孔比表面积所占比例减小,不同粒径煤样对CO气体吸附量与压力成正比;压力一定时,CO吸附量与温度成反比;同温同压条件下,煤样粒径越小,CO吸附量越大;相同温度下,煤对CO饱和吸附量与粒径呈正相关关系,CO解析过程中,粒径减小,饱和吸附量a值增大;煤样对CO吸附速率可划分为3个阶段:0~750 s为快速上升期、750~2 250 s为缓慢上升期、2 250~3 600 s为饱和平衡期;不同粒径煤样CO解吸滞后性随温度的升高而降低;温度相同时煤样粒径越小,CO解吸滞后性越小,达到吸附/解吸的平衡点越容易。