Research of Temperature Tracer Method to Detect Tubular Leakage Passage in Earth-Dam

The location, intensity and scope of concentrated leakage must be determined in order to repair earth-Dam scoured by the leakage. In this paper, firstly, heat tracer theory and distribution laws of temperature in soil body with leakage are discussed. Then temperature tracer model is established according to stable heat conduction theory. In such model, the concentrated seepage passage is simplified into a circular pipe as a boundary condition. The location, scope and flow-velocity of the concentrated leakage are estimated via ichnography of the lowest temperature based on temperature data from detecting wells by quantitative computation and qualitative analysis. In case study, the distribution characteristic of temperature (including temperature data of water in reservoir, drainage pipes and tail pond) can be interpreted by this model. A modified model is also set up, applied for detected data at different cross-sections of the leakage passage, in which the temperature data are rectified according to distances from data locations to calculating section. Finally, the model is solved by numerical iterative method, and the possible error of this theoretical model is discussed. The permeability coefficient in leakage area is identical with that of normal soil in magnitude after anti-seepage repairing accomplished, which indicates this model is effective.

A Review of REE Tracer Method Used in Soil Erosion Studies

Rare earth elements （REEs） have been proved ideal tracers for soil erosion and aggregation. REE tracer method （REETM） used to study soil erosion, as a new technique, has been developed in recent 20 yr. It is able to quantitatively monitor the temporal and spatial variation of erosion intensity, compared with traditional approaches. The applications of REETM in studying of sediment differentiation law, erosion process evolution, determination of sediment sources and sedimentation investigations, and determination of prediction parameters, were reviewed. Some application limitations were summarized.

A theoretical framework of tracer methods for marine sediment dynamics

A new theoretical framework of tracer methods is proposed in the present contribution, on the basis of mass conservation. This model is applicable for both artificial and natural tracers. It can be used to calculate the spatial distribution patterns of sediment transport rate, thus providing independent information and verification for the results derived from empirical formulae. For the procedures of the calculation, first, the tracer concentration and topographic maps of two times are obtained. Then, the spatial and temporal changes in the concentration and seabed elevation are calculated, and the boundary conditions required are determined by field observations (such as flow and bedform migration measurements). Finally, based upon eqs. (1) and (13), the transport rate is calculated and expressed as a function of the position over the study area. Further, appropriate modifications to the model may allow the tracer to have different densities and grain size distributions from the bulk sediment.

Study of fissured-rock seepage flow with isotope tracer method in single borehole

A systematic summary is presented describing the application of isotope tracer method in detecting seepage flow in a single borehole. In a single borehole, many hydraulic coefficients, such as flow velocity, direction of flow, vertical flow etc., can be obtained by using isotope tracer method. There are three conditions if a fissure intersects a borehole: vertical, parallel and tilt. According to each different condition, the formulation of flow velocity deduced by isotope dilution method is different. At the same time, well theory of blended borehole about fissure groups including single fissure group and multi-fissure groups, has also been discussed.

Discrete Tracer Point Method to Evaluate Turbulent Diffusion in Circular Pipe Flow

Diffusion of a solute in turbulent flows through a circular pipe or tunnel is an important aspect of environmental safety. In this study, the diffusion coefficient of turbulent flow in circular pipe has been simulated by the Discrete Tracer Point Method (DTPM). The DTPM is a Lagrangian numerical method by a number of imaginary point displacement which satisfy turbulent mixing by velocity fluctuations, Reynolds stress, average velocity profile and a turbulent stochastic model. Numerical simulation results of points’ distribution by DTPM have been compared with the analytical solution for turbulent plug-flow. For the case of turbulent circular pipe flow, the appropriate DTPM calculation time step has been investigated using a constantβ, which represents the ratio between average mixing lengths over diameter of circular pipe. The evaluated values of diffusion coefficient by DTPM have been found to be in good agreement with Taylor’s analytical equation for turbulent circular pipe flow by givingβ=0.04 to 0.045. Further, history matching of experimental tracer gas measurement through turbulent smooth-straight pipe flow has been presented and the results showed good agreement.

Area Method Analysis and Thermodynamic Behavior of Nonmetallic Micro-Inclusions in Casting Slab of GCr15 Bearing Steel

The distribution and characteristics of nonmetallic micro-inclusions of GCr15 bearing steel were explored through metallographic area method in virtue of tracer method and electronic microscope.The results show that the micro-inclusions,of which the average value is 0.032%,are mainly the compounds formed via the adsorption/aggregation of multielement deoxidized compounds and secondarily deoxidized products on tundish liquid level.The micro-inclusions of diameters from 0 to 5 μm are 92.5% in total,which basically determines the characteristics of inclusions distribution in casting slab.The inclusions of diameters more than 10 μm only account for less than 1% in total,which have little influence on steel quality.The relationship between equilibrium compositions of the first deoxidation products and molten steel compositions was also calculated based on thermodynamic theory.

公立医院护工服务质量评价指标体系构建

目的:构建一套用于评估公立医院护工服务质量评价指标体系,为进一步规范护工人员管理提供依据。方法:基于SERVQUAL模型,结合文献研究、追踪方法学现场调查及两轮德尔菲法专家咨询确定评价指标体系,结合专家决策法和熵值法为指标赋予权重。结果:最终构建的公立医院护工服务质量评价指标体系包含5个一级指标和23个二级指标。17名专家的积极系数均为100%,权威系数分别为0.841和0.842(P<0.001);肯德尔系数逐轮递增(0.218和0.343),专家意见一致性较高。结论:本研究构建的指标体系具备一定的系统性与科学性,能够作为有效评估工具,为护工的服务质量管理提供依据。

Using REE Tracers to Measure Sheet Erosion Changing to Rill Erosion

Rare earth element(REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different REE on different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amount increases with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4.3 and 5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amount. The new REE tracer method should be useful to future studying of erosion processes on slope lands.

智慧供热系统数据运行核查方法研究

高质量数据是智慧供热系统数据分析的前提和分析结论可靠性的保障,计量器具的良好工作状态是获得高质量数据的基础。本文讨论了计量器具的检定、校准及运行核查的区别,研究了智慧供热系统计量器具在线运行核查方法。研究表明:流量计根据其实际安装工作条件,采用安装条件修正系数可解决直管段长度不够带来的测量误差问题;采用基准表法对使用的流量计进行技术性能核查,可正确判别单台流量计的工作状态;示踪法是解决大口径贸易结算表数据质量问题的有效方法。本研究可为及时发现工作异常的计量器具、确保测量数据的准确性及可靠性提供理论指导及技术支撑。

声呐渗流测试技术之质疑

介绍了近年来新出现的用声呐法测试渗流速度和渗流方向这一技术的核心内容,包括测试装置、测试原理和计算方法等。从理论和实践上对其提出了4方面的质疑:测试原理的理论基础、渗流速度计算方法、渗流方向确定和流场畸变。通过理论分析、公式的推导和数据的可靠性分析后认为:声呐测试渗流的原理缺乏理论解释;计算渗流速度的公式反映的只是孔内垂向流速度,实际还是由测量误差产生的伪垂向流速度,且该公式本身就推导不成立;无论垂向流是向上流动或向下流动,探头上部的水声器发射的声波到达下部平面对称分布的6个水声器的时间在理论上是相等的,因而也无法通过合成法求得渗流方向,所提供的渗流方向实际是由指数级时间误差计算得到的伪流向;即声呐法无法获得渗流速度,包括水平向渗流速度和垂直向流动速度,也无法获得水平向渗流方向。

内漏测量技术中浓度衰减法应用模拟研究

核电厂主控室作为核电厂运行的关键位置,在正常和应急情况下保证工作人员在主控室可居留性尤为重要。对核电厂主控室进行可居留性内漏评价能够判断主控室环境是否处于正常安全运行状态,并根据评价结果发现主控室存在的问题进而提出解决方案,是保障主控室正常安全运行的一种评价技术手段。主控室可居留性内漏评价采用示踪气体试验方法,通过浓度衰减法在简单区域进行内漏测量技术模拟研究,结果表明:示踪气体浓度在40 min内能够达到混合均匀,各采样点示踪气体浓度相对标准偏差为3.71%,示踪气体浓度随着时间推移混合均匀性不断提高,房间空气交换次数为0.3/h,内漏量为45 m^(3)/h,空气交换次数的不确定度为0.3/h。采用浓度衰减法进行内漏测量模拟研究,通过对示踪气体注入、采样点布置,气体搅拌装置分布及示踪气体取样分析等过程进行控制,能够实现示踪气体在简单区域内快速混合均匀达到平衡状态。

高建钢Q420GJZ35大型夹杂物行为

对河钢集团唐山中厚板材有限公司生产的高建钢Q420GJZ35大型夹杂物的种类、数量、尺寸等进行了试验研究,并在钢包渣、中间包覆盖剂、中间包打结料中分别加入Ba、La、Ce示踪元素追踪夹杂物来源。研究结果显示:稳态坯中大型夹杂物总体含量为16.8 mg/10kg;非稳态铸坯中含量最高36.2 mg/10 kg,根据示踪检测结果,部分夹杂黏附有钢包渣、结晶器保护渣和保护渣,其中结晶器卷渣是夹杂物的一个重要来源。通过优化改进浸入式水口,将水口由单侧口改为双侧口,侧孔长度由105 mm改为100 mm,水口出口为带圆角的方孔,并进行数值模拟分析。结果显示,改进型水口计算结晶器流场分布合理,表面波动较小,符合设计要求,有利于表面钢液的合金化和杂质的上浮。

ICG荧光示踪法联合亚甲蓝染色在乳腺癌患者前哨淋巴结活检中的应用价值

目的探讨乳腺癌患者前哨淋巴结活检(SLNB)中应用吲哚菁绿(ICG)荧光示踪法联合亚甲蓝染色的临床价值。方法选择118例乳腺癌患者,以随机数字表法分为2组,对照组、观察组各59例。2组均进行SLNB,术中对照组使用亚甲蓝染色法,观察组使用ICG荧光示踪法联合亚甲蓝染色。比较2组SLN检出情况及血压下降、注射部位感染、坏死、发热等并发症发生情况。结果观察组示踪成功率为98.31%(58/59),高于对照组的86.44%(51/59),差异有统计学意义(P<0.05)。观察组共检出246枚SLN,每位患者平均检出(4.17±0.36)枚;对照组共检出162枚SLN,每位患者平均检出(2.75±0.32)枚;组间对比差异有统计学意义(P<0.05)。2组患者术后均未发生明显并发症。结论与单用亚甲蓝染色相比,联合ICG荧光示踪法在乳腺癌患者SLNB中的应用效果更佳,其示踪成功率更高,检出数量更多,临床应用价值较高。

基于REE示踪对红壤细沟间侵蚀团聚体周转和泥沙迁移特征的研究

土壤团聚体是土壤结构的基本单元,土壤表层团聚体的粒径分布变化对土壤结构和侵蚀过程发育具有重要意义。为探究细沟间侵蚀过程中土壤团聚体周转和泥沙迁移路径过程,本研究基于微型土槽,设置90 mm·h-1雨强,10°坡度的条件,进行室内模拟降雨试验。利用稀土元素示踪技术标记土壤团聚体,通过ICP-MS测定稀土元素浓度,对不同粒径土壤团聚体(5~2 mm、2~0.25 mm、0.25~0.053 mm、<0.053 mm)的破碎和形成过程进行定量分析,同时量化侵蚀泥沙的来源特征。结果表明,细沟间侵蚀过程中,侵蚀泥沙颗粒主要由同等粒径大小的团聚体受径流搬运形成,且该粒径泥沙含量随降雨时间增加而减少;残留团聚体呈明显的周转过程,<0.25 mm的团聚体更易粘结或吸附至大粒径团聚体上,而>0.25 mm团聚体倾向于发生破碎(破碎率分别为45.8%和43.3%),且破碎程度不断增加;<0.053 mm和2~0.25 mm大小的泥沙含量及相应粒径的团聚体在泥沙中的贡献率对径流系数和泥沙粒径分形维数具有重要作用。所以,细沟间侵蚀过程中土壤表土结构变化、泥沙迁移与团聚体粒径密切相关,该成果进一步为土壤侵蚀过程模型和水土保持措施提供理论依据。

基于长期氮肥示踪试验评估氮肥利用率算法的合理性

氮肥利用率是衡量氮肥被作物利用的一个指标,常规采用的计算方法为差减法和15N示踪法,主要是通过作物吸收的氮量来计算氮肥利用率。由于这两种方法没有考虑氮肥在土壤中的残留和后效,显著低估了施用氮肥的实际效应。为此,国内外研究者一直在探索更实际的氮肥利用率计算法。不同的改进方法以不同的表现形式包含了氮肥的遗留效应,弥补了差减法和15N示踪法在短期试验中对实际氮肥利用率的严重低估,基本接近于实际氮肥利用率,但远高于常规差减法或15N示踪法估算值。在本文中定义的实际氮肥利用率(ANUE)为:在土壤残留示踪氮被完全消耗的条件下,作物地上部吸收肥料氮占施氮量的百分比。法国28年旱地作物的氮肥叠加利用率为61.3%~65.3%,中国太湖地区17年的水旱轮作体系示踪氮肥试验中氮肥叠加利用率为38.6%~43.0%。本研究采用Origin 2021的图形数字化工具,获取这两个长期定位试验数据,包括每季作物吸收15N、土壤残留15N数据,分别以耗竭耕层(0—20 cm)、1 m、2 m土体中的氮素残留量来计算氮肥利用率。以此为参照标准,评估土壤氮素平衡法和氮肥有效率法计算结果的合理性。基于2 m土体残留肥料氮的土壤氮素平衡法和氮肥有效率法,会高估旱地作物的氮肥利用率;而以耕层土壤残留肥料氮作为估计参数时,则与旱地实际氮肥利用率基本一致(61%~74%);而氮肥有效率(41%~52%)可以很好地估算我国太湖地区水旱轮作体系的实际氮肥利用率。因此,跨地块或作物系统的氮肥利用率比较,应选择适当的计算方法,以避免由不同方法导致的不可比性而产生误解。氮肥有效率法(将作物吸收和土壤残留氮均视为有效部分)可以通过短期试验获得接近实际的氮肥利用率,具有广泛的应用价值。

针对一次对流云降水反演大气垂直运动速度及雨滴谱

反演大气垂直速度和雨滴谱分布是研究云降水机制和云微物理信息的重要内容,对人工预报天气、干预天气都有重要意义。针对2021年8月29日安徽省内毫米波雷达探测到的一次对流云降水过程,处理毫米波雷达的功率谱数据并进行大气垂直速度和雨滴谱反演。在小粒子示踪法的基础上引入改进小粒子示踪法:选取有效云信号段中最小功率对应的谱点作为反演大气垂直速度的示踪物。首先,根据改进前后的小粒子示踪法分别从功率谱数据中反演大气垂直速度,并跟基数据反演大气速度的结果展开对比分析。进一步得到粒子在静止空气中的下落速度,根据现有粒子下落速度-粒子直径之间的经验公式计算反演粒子直径。研究表明:(1)采用改进后的小粒子示踪法反演大气垂直速度得到的结果比小粒子示踪法得到的结果更精确,在云层内部两者误差较大;(2)进一步得到粒子下落速度,结合探测时段的天气状况,得到的粒子速度与大气速度可很好地契合,跟对流云天气情况信息大致吻合;(3)粒子浓度是反演雨滴谱分布时需要注意的主要参数,云在快速发展过程中,内部粒子持续朝外部扩张,云内部的粒子浓度较小,云边界的粒子浓度反而较大。

大口径管道烟气流量测量方法综述

2021年全国碳市场开启,为了提高碳交易的准确性,需要做到碳排放数据的可测量、可报告、可核查。在这种背景下,烟气在线监测系统作为一种碳排放量化方法得到了重视。其有效工作的基础是烟气流量的准确测量。但电厂烟囱尺寸大,内部烟气流动特性复杂,烟气流量难以准确测量。重点分析了皮托管流量计和气体超声波流量计在大口径管道流量测量中的研究现状,详细介绍了大口径管道气体流量测量技术。此外,还介绍了一种独立的流量测量方法—示踪气体稀释法,探讨其发展现状及作为一种流量标定方法的潜力。

砂土孔隙比对示踪剂法测渗流速度影响的试验研究

确定地下水流速对工程建设、生态保护等方面具有重要作用,示踪剂法测量渗流速度是工程中常见方法之一。本文以食盐溶液作为示踪剂,利用电导率变化计算渗流速度,通过自行设计的室内试验装置,分析砂土孔隙比对示踪剂法测渗流速度的影响。研究结果表明:不同孔隙比的砂土层在各水力梯度作用下,测试流速均大于实际流速,误差集中在15%~25%;同一孔隙比的砂土层,实际流速与测试流速的比值基本恒定。为此引入砂土孔隙比修正系数,进一步提高示踪剂法测流速的精确度。

荧光示踪法在沥青材料研究中的应用现状综述

荧光示踪法因能够通过荧光示踪剂标记沥青,帮助研究人员更加直观地观测到沥青的微观结构,从而广泛应用于沥青材料研究中。首先简要介绍了目前广泛应用的4类示踪剂的特点及其应用的主要领域;在此基础上,重点概述了荧光示踪法的原理及在沥青材料研究中常用的荧光示踪剂;接着总结了当下沥青荧光显微试样的制备方法并分析了各种方法的优点与不足;最后综述了荧光示踪法在新-旧沥青融合、沥青改性机理等方向的应用并提出了新型荧光示踪剂使用设想。该研究成果可为荧光示踪法在精确量化分析沥青微观性能方向提供新的研究思路。

季节对浅埋深厚煤层采空区垂直漏风的影响研究

针对浅埋煤层综放面回采后引起地表漏风这一难题,在生辉煤业20100工作面利用示踪气体法研究季节变换时地表的漏风规律,分析不同季节时,采空区和对应地表的温度、压强及漏风速率情况。现场实测结果发现:夏天时,工作面对应地表的温度与采空区温度差值最小,仅为1.0℃;冬天时,工作面对应地表的温度与采空区的温度差值最大,采空区温度都超过20℃,而地表处于0℃以下,二者温度的最大差值达到38.1℃;夏天和冬天释放SF6气体6个区域中采空区和对应地表气压的最大压差分别为21.95 hPa和41.68 hPa;春秋两季的采空区和对应地表气压的差值几乎相同,呈现相同的变化规律;春、秋两季时的漏风速率变化规律大致相同,差异性不明显;夏天时地表具有较小的漏风速率,最大平均值为6.923 m/min;冬天的漏风速率最大,最大平均值为8.294 m/min.根据不同季节的变化特点采取防治漏风措施,确保20100工作面正常生产。