Morphodynamic signatures derived from daily surface elevation dynamics can explain the morphodynamic development of tidal flats

Understanding the sensitivity of tidal flats to environmental changes is challenging.Currently,most studies rely on process-based models to systematically explain the morphodynamic evolution of tidal flats.In this study,we proposed an alternative empirical approach to explore tidal flat dynamics using statistical indices based on long-term time series of daily surface elevation development.Surface elevation dynamic(SED)indices focus on the magnitude and period of surface elevation changes,while morphodynamic signature(MDS)indices relate sediment dynamics to environmental drivers.The statistical analyses were applied to an intervention site in the Netherlands to determine the effect of recently constructed groynes on the tidal flat.Using these analyses,we were able to(1)detect a reduction in the daily SED and(2)determine that the changes in the daily SED were predominantly caused by the reduction in wave impact between the groynes rather than the reduction in tidal currents.Overall,the presented results showed that the combination of novel statistical indices provides new insights into the trajectories of tidal flats,ecosystem functioning,and sensitivity to physical drivers(wind and tides).Finally,we suggested how the SED and MDS indices may help to explore the future trajectories and climate resilience of intertidal habitats.

Influence of bed elevation discordance on flow patterns and head losses in an open-channel confluence

Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics.This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections.A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others.Four configurations with different bed discordance ratios were investigated.The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces.The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step.Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio.It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.

Spectral domain optical coherence tomography crosssectional image of optic nerve head during intraocular pressure elevation

AIM: To analyze changes of the optic nerve head(ONH) and peripapillary region during intraocular pressure(IOP) elevation in patients using spectral domain optical coherence tomography(SD-OCT).METHODS: Both an optic disc 200×200 cube scan and a high-definition 5-line raster scan were obtained from open angle glaucoma patients presented with monocular elevation of IOP(≥30 mm Hg) using SD-OCT. Additional baseline characteristics included age, gender, diagnosis,best-corrected visual acuity, refractive error, findings of slit lamp biomicroscopy, findings of dilated stereoscopic examination of the ONH and fundus, IOP, pachymetry findings, and the results of visual field.RESULTS: The 24 patients were selected and divided into two groups: group 1 patients had no history of IOP elevation or glaucoma(n =14), and group 2 patients did have history of IOP elevation or glaucoma(n =10). In each patient, the study eye with elevated IOP was classified into group H(high), and the fellow eye was classified into group L(low). The mean deviation(MD)differed significantly between groups H and L when all eyes were considered(P =0.047) and in group 2(P =0.042), not in group 1(P =0.893). Retinal nerve fiber layer(RNFL) average thickness(P =0.050), rim area(P =0.015),vertical cup/disc ratio(P =0.011), cup volume(P =0.028),inferior quadrant RNFL thickness(P =0.017), and clockhour(1, 5, and 6) RNFL thicknesses(P =0.050, 0.012, and0.018, respectively), cup depth(P =0.008), central prelaminar layer thickness(P =0.023), mid-inferior prelaminar layer thickness(P =0.023), and nasal retinal slope(P =0.034)were significantly different between the eyes with groups H and L.CONCLUSION:RNFLaveragethickness,rim area,vertical cup/disc ratio, cup volume, inferior quadrant RNFL thickness, and clock-hour(1, 5, and 6) RNFL thicknesses significantly changed during acute IOP elevation.

Extraction and Analysis of Gully Head of Loess Plateau in China Based on Digital Elevation Model

In China′s Loess Plateau area, gully head is the most active zone of a drainage system in gully areas. The differentiation of loess gully head follows geospatial patterns and reflects the process of the loess landform development and evolution of its drainage system to some extent. In this study, the geomorphic meaning, basic characteristics, morphological structure and the basic types of loess gully heads were systematically analysed. Then, the loess gully head′s conceptual model was established, and an extraction method based on Digital Elevation Model(DEM) for loess gully head features and elements was proposed. Through analysing the achieved statistics of loess gully head features, loess gully heads have apparently similar and different characteristics depending on the different loess landforms where they are found. The loess head characteristics reflect their growth period and evolution tendency to a certain degree, and they indirectly represent evolutionary mechanisms. In addition, the loess gully developmental stages and the evolutionary processes can be deduced by using loess gully head characteristics. This study is of great significance for development and improvement of the theoretical system for describing loess gully landforms.

Effect of elevated temperature and silica sand particle size on minimum fluidization velocity in an atmospheric bubbling fluidized bed

The impact of temperature and particle size on minimumfluidizing velocity was studied and analyzed in a small pilot scale of bubbling fluidized bed reactor.This study was devoted to providing some data about fluidization to the literature under high temperature conditions.The experiments were carried out to evaluate the minimum fluidizing velocity over a vast range of temperature levels from 20℃ to 850℃ using silica sand with a particle size of 300-425μm,425-500μm,500-600μm,and 600-710μm.Furthermore,the variation in the minimumfluidized voidage was determined experimentally at the same conditions.The experimental data revealed that the Umf directly varied with particle size and inversely with temperature,whileεmf increases slightly with temperature based on the measurements of height at incipient fluidization.However,for all particle sizes used in this test,temperatures above 700℃ has a marginal effect on Umf.The results were compared with many empirical equations,and it was found that the experimental result is still in an acceptable range of empirical equations used.In which,our findings are not well predicted by the widely accepted correlations reported in the literature.Therefore,a new predicted equation has been developed that also accounts for the affecting of mean particle size in addition to other parameters.A good mean relative deviation of 5.473% between the experimental data and the predicted values was estimated from the correlation of the effective dimensionless group.Furthermore,the experimental work revealed that the minimum fluidizing velocity was not affected by the height of the bed even at high temperature.

Simulating Evolution of a Loess Gully Head with Cellular Automata

This paper presents a new method for simulating the evolution of a gully head in a loess catchment with cellular automata(CA) based on the Fisher discriminant. The experimental site is an indoor loess catchment that was constructed in a fixed-intensity rainfall erosion test facility. Nine high-resolution digital elevation model(DEM) data sets were gathered by close range photogrammetry during different phases of the experiment. To simulate the evolution of the catchment gully head, we assumed the following. First, the 5th and 6th DEM data sets were used as a data source for acquiring the location of the catchment gully head and for obtaining spatial variables with GIS spatial analysis tools. Second, the Fisher discriminant was used to calculate the weight of the spatial variables to determine the transition probabilities. Third, CA model was structured to simulate the evolution of the gully head by iterative looping. The status of the cell in the CA models was dynamically updated at the end of each loop to obtain realistic results. Finally, the nearest neighbor, G-function, K-function, Moran′s I and fractal indexes were used to evaluate the model results. Overall, the CA model can be used to simulate the evolution of a loess gully head. The experiment demonstrated the advantages of the CA model which can simulate the dynamic evolution of gully head evolution in a catchment.

Factors associated with low adherence to head-of-bed elevation during mechanical ventilation in Chinese intensive care units

Background Elevating the head of bed （HOB） 30°-45° has been widely supported as a means of ventilator associated pneumonia （VAP） prevention. However, it was poorly adhered in clinical practice. This observational study aimed to investigate the factors impeding this simple practice at the bedside. Methods This prospective study was conducted in 33 Chinese academic hospital intensive care units （ICUs）. HOB angle was measured four times daily at 5-7 hour intervals. The predefined HOB elevation goal was an angle ≥30°. Results The overall rate of achieving the HOB goal was 27.8% of the 8647 measurements in 314 patients during 2842 ventilation days. The HOB goal of ≥3 times/d was consistently achieved only in 15.9% of the cases. Almost 60% of patients had at least one 24 hours period during which the HOB goal was never documented. This low rate of protocol compliance was not associated with acute physiology and chronic health evaluation （APACHE） II score or dependence on vasopressors. In a survey, ＂nurse workload＂ was identified as the most important factor for non-compliance with the HOB goal. In addition, the rates of compliance were significantly different （P 〈0.001） between physicians self-reporting that they either did or did not know the Institutes of Healthcare Improvement （IHI） ventilator bundle. Conclusions Low adherence to a HOB angle of ≥30° was found in this nationwide survey. Nursing workload and lack of knowledge on VAP prevention were important barriers to changin.q this practice.

Impact of 60 Days of 6~0 Head Down Bed Rest on Cardiopulmonary Function,and the Effects of Taikong Yangxin Prescription(太空养心方) as A Countermeasure

Objective： To study the changes in cardiopulmonary function induced by mid/long-term simulated microgravity with 6^° head down bed rest （HDBR）, and the effects of Taikong Yangxin Prescription （太空养心方, TYP） as a countermeasure. Methods： Fourteen healthy male volunteers were randomly divided into a control group and a Chinese medicine （CM） group （7 in each group） by a random digital table based on their body weight. Both groups underwent6^° HDBR for 60 days. Subjects in the CM group received daily TYP pills and subjects in the control group received daily placebo pills. Cardiac systolic and pumping functions were measured by echocardiography before HDBR; on days 20, 42, and 57 of HDBR; and on day 3 of recovery after HDBR （R＋3）. Cardiopulmonary functional reserve and exercise capacity were evaluated before HDBR, on day 29, and on day R＋3 by exercise testing. Results： The heart rate （HR） increased gradually during HDBR. The HR was significantly higher on day 57 than before HDBR in the control group （P〈0.05）, but did not increase significantly in the CM group. The stroke volume/stroke volume index, ejection fraction, and left ventricular fractional shortening tended to decrease over time in the control group, but not in the CM group. These parameters were significantly higher in the CM group than in the control group on day 42 （P〈0.05 or P〈0.01）. Exercise testing showed that maximum 02 consumption （VO2max）, metabolic equivalents, relative 02 consumption （VO2）, 02 pulse, and exercise duration were significantly lower on day 29 than before HDBR in the control group, but not in the CM group. Conclusions： Sixty days of 6^° HDBR induced a reduction in cardiac systolic and pumping functions, and reduced cardiopulmonary functional reserve and exercise capacity. Administration of TYP significantly improved cardiac systolic and pumping functions, and maintained cardiopulmonary functional reserve and exercise capacity.

长期模拟失重后直立性紫癜与心血管、血液和尿液指标关联性分析

针对航天飞行后或模拟失重生理效应实验后会出现直立性紫癜的问题,开展心血管、血液和尿液等表型指标关联性研究。在地星二号90 d头低位卧床模拟失重实验中,招募36位志愿者,头低位实验结束后发现7名志愿者发生了直立性紫癜现象。通过261个表型组指标与直立性紫癜的关联分析,研究了与直立性紫癜发生显著相关的表型指标。结果表明:单核细胞绝对值(校正后P=0.0064)、单核细胞百分比(校正后P=0.0452)及血小板计数变化(校正后P=0.0100)等指标与直立性紫癜的形成有显著相关性。

基于改进YOLOv5s模型的电梯内电瓶车检测方法

针对现有检测模型不能满足在实时场景下准确检测电梯内电瓶车的问题,提出一种改进YOLOv5s模型的电梯场景下电瓶车检测方法。改进模型将全局注意力机制融合到YOLOv5s模型的颈部特征融合网络中,来增强模型对融合特征的学习能力;使用充分解耦的检测头部替换原YOLOv5s模型的耦合头部,将目标检测过程中目标分类判定和边框回归这两个子任务解耦,以提升模型检测的准确度。实验结果表明,在自建电梯内电瓶车图像数据集E-Car上,改进YOLOv5s模型显著提高了检测效果,检测指标P、R、mAP_0.5和mAP_0.5∶0.95分别达到94.5%、92.2%、96.9%和64.5%,比原模型分别提高4.3%、2.8%、3.8%和4.6%。相比其他主流的目标检测模型,改进YOLOv5s模型在保持一定检测速度的前提下,具有更高的检测精度,能够实现高效的电梯内电瓶车检测。

抗滑桩爆破开挖引起多台阶顺层岩质边坡振动响应分析

为了研究临近抗滑桩施工爆破引起多台阶顺层边坡的振动响应规律,结合巫镇高速公路边坡工程,联合LS-DYNA和FLAC3D软件建立了抗滑桩爆破模型和多台阶顺层岩质边坡动力计算模型,分析了抗滑桩施工爆破荷载特征及其引起多台阶顺层边坡振动速度变化规律。结果表明,抗滑桩施工爆破最大荷载具有水平向小、竖向大的特点,其引起边坡坡面的振动响应特征表现为①坡体下部水平振速大于竖向振速,坡体上部竖向振速大于水平振速;②多台阶顺层岩质边坡坡面具有高程放大效应,且竖向振速放大率大于水平振速;③多台阶顺层岩质边坡内部具有“趋表放大效应”,坡体不同部位的“趋表放大效应”特征显著不同;④坡面下部水平向振速衰减率大于竖向衰减率,坡面上部竖向衰减率(放大率)大于水平向衰减率,各阶边坡坡脚处振动速度衰减率大于坡顶处衰减率。

宁南黄土丘陵区侵蚀沟不同部位植物多样性与土壤养分

[目的]探明宁南黄土丘陵区侵蚀沟不同部位植物多样性与土壤养分的关系,为侵蚀沟的水土保持及防护提供依据。[方法]以宁夏彭阳县玉洼流域3个稳定侵蚀沟的沟头、沟床、沟岸为对象,通过野外植被调查,同时采集0—10,10—25,25—40,40—55,55—70 cm土样,在室内测定土壤有机碳、土壤全氮、土壤全磷含量,分析了侵蚀沟不同部位(沟头、沟床、沟岸)的植物多样性及土壤养分特征。[结果]侵蚀沟沟头植物隶属3科6属,禾本科4属4种,伞形科和豆科各1属1种;沟床植物隶属5科12属,禾本科4属4种,菊科5属5种,豆科、茜草科和伞形科各1属1种;沟岸植物隶属3科7属,禾本科4属4种,豆科2属2种,伞形科1属1种。侵蚀沟各部位植物种数表现为:沟床>沟岸>沟头,均以禾本科植物为主。生活型上,各部位均以多年生草本植物搭配一、二年生草本植物为主。侵蚀沟的地上生物量、Shannon-Wiener指数、Patrick指数和Margalef指数均表现为:沟床>沟岸>沟头;Simpson指数表现为:沟头>沟床>沟岸;Pielou指数表现为:沟头>沟岸>沟床。侵蚀沟各部位平均土壤有机质、土壤全磷和土壤全氮含量均表现为:沟床>沟岸>沟头,且主要集中在0—10 cm和55—70 cm。侵蚀沟沟头和沟岸的地上生物量与土壤有机碳呈极显著正相关(p<0.01)、与土壤全磷呈显著正相关(p<0.05);侵蚀沟沟床的Shannon-Wiener指数与土壤全磷呈显著负相关(p<0.05),地上生物量与土壤有机碳呈极显著正相关(p<0.01)。[结论]侵蚀沟沟头易崩塌且土壤养分条件较差,应配置根系发达、茎干粗壮、耐冲性强的乡土树种,沟床、沟岸养分较高可优先配置碳、氮、磷含量需求较大的草本或灌木。

侵蚀基准面下降对弯道河床演变的影响

概化设计了一在出口处布设有高度可变的拦沙坎的弯曲河道模型,利用声学多普勒流速仪和数字波高仪测得13个特征断面的瞬时流速与瞬时水位数据,依托激光扫描技术获得试验床面的精确数字高程,以此来探讨侵蚀基准面下降对弯道河床演变的影响。结果发现:粗化层对河床有一定的保护作用,当侵蚀基准面小幅下降而导致流速小幅增大时,粗化层的保护作用可一定程度地抵减流速的增量,减弱甚至避免水流对河床的冲蚀;当侵蚀基准面下降幅度较大时,河床会被全局冲蚀,但各局部的被冲蚀程度并不相同,其中过渡段主流带的被冲蚀程度较小,弯段凹侧主流顶冲区的被冲蚀程度较大;越靠近侵蚀基准面的区域,侵蚀基准面的下降越易增强该区域的水流强度,越易使该区域的河床被冲蚀;在侵蚀基准面下降幅度较小且槽底未见裸露的情况下,连续弯道完整周期的床面高程频率分布总体上接近于正态分布,但若从细节上看其分布具有双峰特征;双峰特征为半周期床面高程频率分布所特有,完整周期床面高程频率分布的双峰特征只是半周期床面高程频率分布双峰特征叠加的结果;当侵蚀基准面下降至槽底时,主流顶冲区的槽底会严重裸露,连续弯道完整周期的床面高程频率分布仍具有双峰特征,但其总体形态已明显偏离正态分布。

组合式减振道床对箱梁振动声辐射的影响分析

为研究一种新型组合式减振道床对城市轨道交通高架箱梁振动声辐射的影响,基于有限元-边界元的方法建立轨道-箱梁耦合振动声辐射模型,采用轮轨相互作用模型获得轮轨作用力作为激励,并采用现场试验结果进行模型验证;利用该模型对比分析采用整体道床和组合式减振道床的箱梁结构振动声辐射特性,调查不同运行车速和组合式减振轨道中不同刚度扣件对箱梁结构噪声的影响。结果表明:相比整体道床,采用垂向刚度18 kN/mm减振扣件和面刚度18 kN/mm3减振垫的组合式道床可降低箱梁底板加速度振级17.9 dB,降低底板下方的声压级14.6 dB;随着车速的增大,箱梁振动噪声水平逐渐增大,当车速从60 km/h提高至160 km/h时,测点A处总振级增大8.5 dB,测点M处总声压级增加8.1 dB;采用垂向刚度为6 kN/mm减振扣件时,箱梁底板附近总体声压级比采用18 kN/mm和30 kN/mm扣件时分别减小1.8 dB和8 dB。

宁南山区侵蚀沟不同部位土壤理化性质及可蚀性研究

侵蚀沟沟头前进,沟岸扩张,沟床下切严重影响区域粮食生产和环境质量。以宁夏彭阳县玉洼流域3个稳定侵蚀沟的沟头、沟床、沟岸为对象,通过野外调查取样与室内试验相结合的方法,分析了侵蚀沟不同部位(沟头、沟床、沟岸)的土壤理化性质及可蚀性K值,采集0—10,10—25,25—40,40—55,55—70 cm土壤,测定并计算土壤质量含水量(θ)、土壤容重(ρ)、土壤总孔隙度(φ)、土壤黏粒(CLA)、粉粒(SIL)、砂粒(SAN)含量、>0.25 mm水稳性团聚体含量(R 0.25)、土壤平均重量直径(MWD)、土壤几何平均直径(GMD)及土壤有机质(SOM)含量,利用EPIC模型计算土壤可蚀性K值。结果表明:(1)侵蚀沟各部位平均质量含水量、总孔隙度、有机质、粉粒含量、>0.25 mm水稳性团聚体含量、平均重量直径、几何平均直径的大小顺序均为沟床>沟岸>沟头,各部位平均土壤容重、砂粒含量为沟头>沟岸>沟床,平均土壤黏粒含量为沟岸>沟头>沟床,各部位土壤机械组成均为粉粒含量>砂粒含量>黏粒含量;(2)侵蚀沟各部位土壤可蚀性K值在0.0329~0.0395(t·hm^(2)·h)/(MJ·mm·hm^(2)),属于中可蚀性,平均可蚀性K值表现为沟头>沟岸>沟床;(3)侵蚀沟各部位土壤可蚀性K值与土壤粉粒、黏粒含量呈显著负相关,与土壤砂粒、有机质含量、质量含水量呈显著正相关,沟床土壤可蚀性K与R 0.25、MWD、GMD呈极显著负相关(p<0.01)。沟头作为侵蚀沟发育最活跃的部位,通过提高土壤有机质含量、粉粒含量来增加团聚体的数量和稳定性,从而降低土壤可蚀性。研究结果可为侵蚀沟生态稳定性及评估提供依据。

煤巷掘进工作面声发射监测传感器超前布设工艺研究

为实现对煤巷掘进工作面掘进过程声发射监测信号的有效采集,确保监测效果真实可靠,对煤巷掘进过程声发射监测传感器超前布设工艺进行了研究。在掘进工作面本煤层顺层钻孔与底板巷穿层钻孔安装传感器,考察监测工艺可行性以及监测信号的有效性与真实性。研究结果表明:可伸缩式弹性倒爪机构可实现传感器在顺层与穿层钻孔内的有效安装,但基于工程现实客观条件,底板巷穿层钻孔安装传感器更具可行性;同时通过该传感器所采集的监测信号更接近煤岩体内产生的真实信号,从而确立了煤巷掘进工作面声发射监测传感器宜采用底板巷穿层钻孔布设的安装工艺,该工艺可有效提升监测信号真实性与可靠性,并进一步完善了煤巷掘进工作面声发射监测技术体系。

加固材料对运动场移动式草坪质量及坪床性能的影响

本研究以高羊茅(Festuca arundinacea)品种‘钛极2LS’为试验材料,以无加固材料运动场移动式草坪为对照(CK),使用践踏器模拟中等强度践踏,分析加固剂和植物纤维对移动式运动场草坪坪观质量、坪床性能及运动质量的影响。结果表明:在践踏两周内,以0.4%纤维网片为加固材料的处理对草坪的色泽、归一化植被指数(NDVI)及坪观质量评价分析表明有显著提升效果(P <0.05),践踏4周后,各处理色泽、NDVI及坪观质量评价分析与CK差异不显著(P> 0.05)。以1%聚氨酯加固剂为加固材料的处理(WOH)可以有效维持土壤紧实度,以纤维与加固剂复合材料(0.4%椰丝+0.1%聚丙烯酰胺)为加固剂的处理(YP)显著提升草坪表面硬度与扭动摩擦,但YP处理会显著增加球员头部损伤风险(P <0.05)。在践踏4周后,坪床结构受到践踏扰动,各加固材料处理的加固性能显著下降(P <0.05)。综上所述,在中等践踏强度下,移动式运动场坪床的加固材料使用土壤加固剂1%聚氨酯可以有效保证坪床的稳定结构,降低球员受伤风险,且能满足高质量运动场的质量要求。

改良式托取胎头法在头位剖宫产术中胎头高浮的应用效果分析

目的探讨在头位剖宫产手术中对出现胎头高浮的产妇应用改良式托取胎头法(improved method of holding fetal head,IMHFH)的效果。方法随机选择2019年10月—2021年3月在莆田市妇幼保健院行剖宫产手术且手术过程中出现胎头高浮的100例产妇作为研究对象,采用随机数表法分为两组,对照组50例应用手入宫腔取胎头法,观察组50例使用IMHFH,记录两组产妇治疗后子宫切口出现撕裂的情况、术中出血量、胎头娩出时间、产褥期并发症的发生情况,新生儿出生1 min后,5 min后,10 min后的Apgar评分及术后24 h的疼痛程度。结果观察组子宫切口撕裂的情况明显少于对照组,术中出血量明显少于对照组,胎头娩出时间短于对照组,差异有统计学意义(P<0.05)。观察组产褥期总并发症发生率为4.00%,明显低于对照组26.00%,差异有统计学意义(χ^(2)=9.490,P=0.002)。观察组新生儿出生1 min后,5 min后,10 min后的Apgar评分均明显高于对照组,差异有统计学意义(P<0.05)。观察组产妇治疗后24 h VAS评分明显低于对照组,差异有统计学意义(t=63.180,P<0.001)。结论对头位剖宫产手术中出现胎位高浮的产妇应用IMHFH可以有效改善产妇术后出现子宫切口撕裂的情况,降低术中出血量,减短胎头娩出的时间,降低产褥期并发症的发生率,新生儿出生后窒息出现情况减少。

安全壳地坑过滤器的碎渣层压损计算研究

NUREG/CR-6224公式广泛应用于安全壳地坑过滤器的碎渣层压损计算。本文首先研究了碎渣层压损的具体迭代计算方法,其次重点分析了最小纤维层厚度、极限压缩比、过压缩、薄层效应、未压缩等特殊工况及计算解决方法。根据计算值与试验结果的对比,指出应当考虑滤网有效面积随碎渣量的变化,并针对折弯板式滤网提出了1.3的压损修正系数。