Impacts of Water-Sediment Regulation Scheme on Chromophoric Dissolved Organic Matter in the Lower Yellow River

As a river with more than 3000 reservoirs in its watershed,the Yellow River has been affected by dams not only on the sediment load,but also on the water quality.Water-sediment regulation scheme(WSRS),which has been carried out annually in the Yellow River since 2002,is a typical human activity affecting river water quality.Chromophoric dissolved organic matter(CDOM)in river is susceptible to changes in ecological and environmental conditions as well as human activities.Here,we report variations in dissolved organic carbon concentrations,compositions and sources of CDOM in time series samples in the lower Yellow River during WSRS.In addition,a parallel factor fluorescence analysis(PARAFAC)method is applied to identify different fluorescent components in water samples during WRSR,showing four major components including tryptophan-like component(C1),microbial humic-like component(C2),terrestrial humic-like component(C3)and tyrosine-like component(C4).In general,C1 increased after water regulation,while C2 and C3 increased after sediment regulation,indicating that the water and sediment released by the dam have different effects on CDOM compositions.Under the impacts of the dam,source of CDOM in the lower Yellow River is mainly autochthonous related to microbial activities,and is regulated by the terrestrial input during WSRS period.Sediment resuspension inhibits microbial activities and reduces the production of autochthonous CDOM.Overall,human activities especially WSRS,as exemplified here,significantly alter the quality and quantity of CDOM in the lower Yellow River,affecting CDOM dynamics and biogeochemical processes in the estuarine environment.

Effect of water-sediment regulation and its impact on coastline and suspended sediment concentration in Yellow River Estuary

Implementation of the water-sediment regulation(WSR) scheme, mainly focused on solving the sedimentation problems of reservoirs and the lower reaches of the Yellow River, has inevitably influenced the sediment distribution and coastal morphology of the Yellow River Estuary.Using coastline delineation and suspended sediment concentration(SSC) retrieval methods, this study investigated water and sediment changes,identified detailed inter-annual and intra-annual variations of the coastline and SSC in the normal period(NP: 1986-2001, before and after the flood season) and WSR period(WSRP: 2002-2013, before and after WSR). The results indicate that(1) the sedimentation in the low reaches of the Yellow River turned into erosion from 2002 onward;(2) the inter-annual coastline changes could be divided into an accretion stage(1986-1996), a slow erosion stage(1996-2002), and a slow accretion stage(2002-2013);(3) an intra-annual coastline extension occurred in the river mouth in most years of the WSRP; and(4) the mean intra-annual accretion area was 0.789 km^2 in the NP and 4.73 km2 in the WSRP,and the mean SSC increased from 238 mg/L to 293 mg/L in the NP and from 192 mg/L to 264 mg/L in the WSRP.

Impact of the water-sediment regulation and a rainstorm on nutrient transport in the Huanghe River

Dissolved nutrient concentration in the Huanghe （Yellow） River at Lijin was monitored during a water-sediment regulation period and a subsequent rainstorm from 14 June to 19 July, 2005. This study provides detailed information on nutrient concentrations in the Huanghe River during the water-sediment regulation and rainstorm periods, and is of significance for the downstream area of the Huanghe River and the Bohai Sea. The average concentrations of nitrate, nitrite and ammonia were 304.7 μmol/L, 0.19 μmol/L, and 1.10 μmol/L, respectively, while the average concentrations of dissolved inorganic phosphorus （DIP） and dissolved silicate （DSi） were 0.23 gmol/L and 122.9 ktmol/L, respectively. Nutrient concentrations during the water-sediment regulation period were mainly influenced by the dilution effect, floodplain effect and sediment resuspension while dilution and erosion effects were the main factors during the rainstorm. The fluxes of dissolved inorganic nitrogen （DIN）, DIP and DSi during the water-sediment regulation and rainstorm periods accounted for 20.4%, 19.5%, 16.7% and 4.97%, 6.45%, 5.47% of the annual nutrient fluxes, respectively. Discharge was the main factor influencing the fluxes of nutrients during both the water- sediment regulation and the rainstorm periods.

The influence of water-sediment regulation on macrobenthic community structures in the Huanghe River(Yellow River)Estuary during 2012–2016

To determine if water-sediment regulation has affected macrobenthic community structure in the Huanghe River Estuary,China,macrobenthic samples were collected following regulation events from 2012 to 2016.We identify seven phyla and 138 macrobenthic species from within samples throughout the survey area,over time.Species richness and abundance in 2012 were significantly higher than in 2016.Biomass did not differ significantly during 2012–2016.Dominant species were mostly small polychaetes,with mollusks,arthropods,and echinoderms all being relatively rare.In 2016,dominant species were small polychaetes.MDS reveals macrobenthic communities at all surveyed distances from the estuary to have become the same community structure over time.Shannon-Wiener diversity and Margalef richness indexes trended down over time.CCA reveals the most dominant sediment-dwelling species to prefer lower dissolved oxygen,sulfides,and pH,and sediments with high D50 and low clay content.We speculate that water-sediment regulation has affected seabed communities,particularly Region A in our survey area.

Experimental study on large wood filtration performance by herringbone water-sediment separation structure

A herringbone water-sediment separation structure(hereinafter referred to as "herringbone structure") has been shown to be effective in separating coarse inorganic debris; however, less is known regarding the large wood(LW) filtration effect in this structure. This paper presents preliminary research on the wood filtration effect of the herringbone structure based on physical model tests.The results show that the herringbone structure exhibited effective performance in large wood size segregation, with a 100% component filtration rate for LW that diameter(D) larger than ribbed beam opening width(a). The total filtration rate also exceeded 80% when the Fraud number(Fr) is larger than 2.64 and increased with the increase of Fr. After exceeding Frmax, total filtration rate would be decreased due to overflow. Beside flow condition,structure parameters influence significantly on LW filtration rate. We attempt to explain the filtration process via particle contact trajectory and particle movement trajectory. The inclined angle of ribbed beam(γ) contributed the most variation to the filtration rate via influencing the coincidence with particle contact trajectory and particle movement trajectory. The high sensitivity coefficient of ribbed beam(θ) under relatively low Fr conditions implies remarkable influences on LW filtration effects by causing clogging problem. The ribbed beam opening width(a) together with LW diameter(D) influenced the size segregation performance.

Nutrient exchange and release experiment and its simulation study in lake water-sediment interface

The sediment distributed and insolated under lake was collected for experiments. The nutrient layer distribution conditions of sampled sediment and its physical and chemical characteristics were analyzed to simulate and assess the influence degree to lake water quality. Based on the dynamic water exchanging experiments the nutrient release process in sediment and influence mechanism to substance exchanging on water-sediment interface was studied, and the correlation between the changing content of total phosphors and total nitrogen in sediment and covered water were analyzed for setting up a simulation model. At the same time the influence degree is explained in detail. The experimental results indicated that even if clean water without nutrient contents was used for water exchangement so as to decrease pollution or prevent eutrophication, however owing to the vertical nutrient distribution in lake sediment, it will lead to the increasing release amount greatly especially when the organic nutrient contained in sediment turns into inorganic status because of isolation. Besides the release process of total phosphate （TP） and total nitrogen （TN） were modeled and each nutrient＇s exchanging equation at interface caused by covered water nutrient concentration changing was set up. According to the simulating prediction, TP and TN content of cover water will also sustain a steady higher level in a long period. The nutrient release amount of sediment is not only affected by the covered water concentration but also connects with accumulative time. The experiments provide the fundamental theoretical and practical basis for taking ecological restoration project. And research is helpful to prevent or restore lake eutrophication.

Impact of Water-Sediment Regulation on Variations of Amino Acids in the Middle-Lower Yellow River, China

In order to examine the impacts of water-sediment regulation on regional carbon cycling,we collected water,particulate and sediment samples from the middle-lower Yellow River in late June and early July,2015 and analyzed their specific amino acids(AA),DOC,POC,and bacteria abundance.Summarized by 14 specific AA,the total hydrolysable AA(THAA),particulate AA(PAA),and sediment AA(SAA)varied in ranges of 2.29-9.05μmol L^-1,5.22-22.96μmol L^-1,and 81.7-137.19μg g^-1 dry weight.After the regulation,dissolved free AA(DFAA)decreased by 29%while DCAA increased by 72%.These variations suggested that DFAA were further degraded,while DCAA molecules were further activated.Meanwhile,PAA increased almost 4 times as many as those before regulation,and SAA increased as well.After regulation,the amounts of bioactive amino acids(Asp,Glu and Gly)increased in THAA but decreased in PAA,with little changes in SAA.The ratios of Asp/Gly in different phases increased after regulation,indicating the AA contributions were promoted by calcareous organisms rather than by siliceous organisms.Multiple correlation analysis showed that PAA was primary representatives of AA and organic carbon,followed by DCAA and POC.Moreover,bacterial reproduction played a key role in shaping the AA compositions and properties,followed by the redox condition and acid-base balance.The results of this study provided a clear evidence for the effects of water-sediment regulation on regional biogeochemistry of organic carbon in the middle-lower Yellow River.

Determination of optimal grid opening width for herringbone water-sediment separation structures based on sediment separation efficiency

The herringbone water-sediment separation structure(HWSSS) was developed to prevent debris flows. This paper mainly focuses on evaluating the sediment separation efficiency of HWSSS in debris flow prevention and determining the grid opening width D, a crucial structure parameter for HWSSS design. Theoretical analysis on the total sediment separation rate Pt reveals that the efficiency of sediment separation is much related with sediment grain size distribution(GSD) and grid opening width. The lower limit of Pt is deduced from the perspective of safety consideration by transforming debris flow into sediment-laden flow. Hydraulic model tests were carried out. Based on the regression analysis of the experimental data, the quantitative relationships between Pt and D and GSD characteristic values were finally established. A procedure for determining optimal grid opening width is proposed based on these analyses. These results are of significance in evaluating sediment separation effect by HWSSS in debris flow prevention and contribute to a more explicit methodology for design of HWSSS.

THE STUDY ON THREE-DIMENSIONAL MATHEMATICAL MODEL OF RIVER BED EROSION FOR WATER-SEDIMENT TWO-PHASE FLOW

Based on the tensor analysis of water-sediment two-phase how, the basic model equations for clear water flow and sediment-laden flow are deduced in the general curve coordinates for natural water variable-density turbulent how. Furthermore, corresponding boundary conditions are also presented in connection with the composition and movement of non-uniform bed material. The theoretical results are applied to the calculation of the float open caisson in the construction period and good results are obtained.

Environmental Flow Assessment Using Water-Sediment Approach at the Sekampung River, Indonesia

Environmental issue has been considered more significant in many aspects of engineering decision-making process particularly in river management. There is an increasing effort to conserve functioning of rivers for human use as well as nature, therefore environmental flow assessment has been widely developed. This paper discusses on environmental flow assessment of the Sekampung River, particularly on its middle reach. A new analytical approach based on water-sediment equations was introduced in order to determine a minimum environmental flow at the certain cross section of a river. The result of the new method was then compared with a minimum environmental flow provided by using two hydrological based methods, namely, Tennant and Flow Duration Curve Analysis (FDCA) method. The result shows that the concerned discharge provided by the water-sediment method (3.5 m3/s) is the smallest compare with a minimum environmental flow that is provided by both Tennant (5.7 m3/s) and FDCA method (4.5 m3/s). It is promising that the water-sediment method can be used as a simple approach on preliminary state of environmental flow assessment. The method involves not only water discharge but also its related sediment flow of the river in order to mitigate further ecological and morphological risks.

REE distribution in water-sediment interface system at deep ocean floor

REE concentrations and distribution patterns in the different phases of water-sediment interface system at deep ocean floor were studied on the basis of samples of bottom water, sediments, interstitial water and polymetallic nodules collected from the East Pacific Basin by R/V Haiyang 4 during HY4-871 and HY4-881Cruises. It is suggested that REE concentrations in oxic interstitial water are lower than that in bottom weter,REE contents of polymetallic nodules, except Ce, are similar to that of sediments. Bottom water, sediments and interstitial water are almost the same in REE distribution patterns. MREE enrichment relative to LREE and HREE and negative Ce anomalies, MREE earichment has been found in polymetallic nodules,and Ce shows positive anomalies. REE contents in sediments increase with depth, and the vacations of distribution patterns with depth have not been found.

Solid Rocket Booster Thrust Asynchrony Identification Method for Solid Rocket Bundled Rockets With ESO

The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.

On Asynchrony in Multisensor Distributed Detection

In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with asynchrony which could be much ciooer to industrial practice.

Patient–ventilator asynchrony in Saudi Arabia: Where we stand?

Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of patient–ventilator asynchrony and how to step ahead for better patients'ventilation management.

Time-asynchrony identification between inertial sensors in SIMU

Traditional strapdown inertial navigation system （SINS） algorithm studies are based on ideal measurements from gy- ros and accelerometers, while in the actual strapdown inertial measurement unit （SIMU）, time-asynchrony between each iner- tial sensor is inevitable. Testing principles and methods for time- asynchrony parameter identification are studied. Under the single- axis swaying environment, the relationships between the SINS platform drift rate and the gyro time-asynchrony are derived using the SINS attitude error equation. It is found that the gyro time- asynchrony error can be considered as a kind of pseudo-coning motion error caused by data processing. After gyro testing and synchronization, the single-axis tumble test method is introduced for the testing of each accelerometer time-asynchrony with respect to the ideal gyro triad. Accelerometer time-asynchrony parame- ter identification models are established using SINS specific force equation. Finally, all of the relative time-asynchrony parameters between inertial sensors are well identified by using fiber optic gyro SIMU as experimental verification.

机械通气人机不同步自动检测算法综述

该研究总结了患者与呼吸机非同步性(patient-ventilator asynchrony,PVA)自动识别技术在机械通气过程中的应用。在早期阶段,规则及阈值的设定方法依赖于呼吸机参数及波形的人为解析,虽然这类方法直观并易于操作,但在阈值设定和规则选择上相对敏感,不能很好地适应患者状态的微小变动。随后,机器学习和深度学习的技术开始出现并发展。这些技术通过算法自动提炼和学习数据特性,使PVA的检测更具鲁棒性和通用性。其中,逻辑回归、支持向量机、随机森林、隐马尔可夫模型、卷积自编码器、长短期记忆网络、一维卷积神经网络等方法都被成功地用于PVA的识别。尽管深度学习方法在特性提取上取得了显著进步,但是它们对标签数据的需求较大,可能会消耗大量医疗资源。因此,强化学习与自监督学习的结合可能是一个实际可行的解决方案。此外,算法的验证大多基于单一的数据集,未来对于跨数据集验证的需求将是一个重要且充满挑战性的发展方向。

慢性心力衰竭患者心电图QRS波时限与心室电-机械不同步的关系

目前许多研究表明,QRS波时限与心室机械不同步并非完全呈线性关系,然而心室同步电激活是心室正常收缩舒张的重要先决条件。慢性心力衰竭(简称心衰)患者常常存在心室收缩功能障碍。尽管心衰初期心脏会发生适应性改变,但一旦超过代偿范围,就会导致心脏重构,使心功能严重受损。心电-机械重构受心脏结构、细胞水平和分子水平等因素的多重影响,在心电图上可以表现为QRS波时限增宽。在心衰的治疗方面,除了传统起搏器以外,近些年新兴的传导系统起搏更符合生理传导的特点,能在显著缩短QRS波时限的同时显著改善心室的机械同步性。本文综述了慢性心衰患者发生电-机械不同步的可能机制及其与QRS波时限的关系,以及二者对心功能的影响。

吉林蛟河针阔混交林不同尺度下生物量稳定性及影响因子

【目的】探讨不同空间尺度下物种多样性、结构多样性、物种异步性、林分密度和环境因素对群落生物量稳定性的影响及相互之间的作用路径,旨在解析生物量的稳定性在不同空间尺度上的主要驱动因素,为森林的可持续经营及科学管理提供理论基础。【方法】以吉林蛟河针阔混交林为研究对象,利用2010—2020年的样地群落调查数据,通过结构方程模型探讨20 m×20 m和40 m×40 m两个空间尺度上生物因素(物种多样性、结构多样性、物种异步性、林分密度)和非生物因素(地形因子、土壤理化性质)与群落生物量稳定性间的关系及作用机制。【结果】在20 m×20 m空间尺度上,生物量稳定性与物种异步性、结构多样性、林分密度均有显著正向关系,非生物因素中地形因子(坡度、凹凸度)与生物量稳定性呈正相关关系;而在40 m×40 m空间尺度上,生物量稳定性与物种异步性呈现显著正相关,非生物因素中土壤理化性质(速效钾、全磷和速效氮)与生物量稳定性呈现负相关关系。结构方程模型分析表明,在20 m×20 m空间尺度上,物种异步性对生物量稳定性的影响高于林分密度和结构多样性,路径系数为0.40。土壤理化性质(全钾、全氮和速效氮)通过显著影响物种多样性间接作用于生物量稳定性,路径系数为0.10。在40 m×40 m空间尺度上,生物因素中只有物种异步性对生物量稳定性有显著正向影响,路径系数为0.64。地形因子(坡度、凹凸度)通过调整结构多样性间接作用于林分生物量稳定性,路径系数为0.35。【结论】在不同的空间尺度上,虽然生物因素与非生物因素对生物量稳定性的作用路径和影响力不尽相同,但物种异步性均为生物量稳定性的主要驱动因子。在20 m×20 m空间尺度上,物种异步性、林分密度、结构多样性等生物因素通过直接正向效应来影响生物量稳定性,非生物因素通过间接效应作用于生物量稳定性;在40 m×40 m空间尺度上,林分生物量稳定性主要影响因子则是物种异步性和土壤理化性质。

基于随机异步性的大跨度钢连廊整体提升施工过程分析研究

针对扬州某科技园大跨度钢连廊高空整体提升施工进行模拟分析,提出实际吊装过程中可能出现的提升节点异步性问题,并针对提升节点不同步的问题,利用有限元软件SAP2000模拟分析连廊在提升过程中的随机异步性在提升、加固施工过程中的随机异步性,根据相关规范与实际施工状态对模拟参数进行取值,利用模拟数据得出吊点之间的随机偏移。分析结果可知:在实际施工过程中,应注重钢绞线的选择,对提升节点进行提升前预起拱等施工操作,同时精细化操作提升机械,尽力减少节点随机异步性的影响。

考虑相量量测单元数据不同步的双端输电线路正序以及零序参数辨识方法

针对相量量测单元(phasormeasurementunit,PMU)数据不同步导致参数辨识结果误差大的问题,提出了考虑PMU数据不同步的输电线路正序以及零序参数辨识方法。首先,分析线路集中参数模型和分布参数模型在一定电压等级下的长度适用范围。基于线路的集中参数模型,利用正常运行情况下PMU装置获取的线路两端功率以及电压信息,构建以正序参数和不同步角度为未知量的非线性方程,并运用Levenberg-Marquardt(L-M)算法求解正序参数以及不同步角度。其次,在辨识出正序参数以及不同步角度的基础上,分析单相接地故障情况下的正序、负序以及零序等效电路图,通过正序和负序网络求解出故障距离。在故障距离已知的情况下,基于零序网络构建以零序参数为未知量的方程,并利用L-M算法求解方程。最后,利用MATLAB软件搭建单回双端输电线路系统,并对所提正序以及零序参数辨识方法进行仿真,验证了所提参数辨识方法的有效性和精确性。