应用于船舶与海洋工程结构安全监测的应变传感器技术研究

目的 研制适用于船舶与海洋工程结构安全监测的应变传感器,并提出标定方法。方法 针对海洋环境特点,考虑传感器封装技术,通过结构设计与有限元仿真计算,研制以弹性体和电阻应变片为主要组成的应变传感器。设计传感器专用标定梁,并完成标定流程的制定和数据处理方法的研究,开展标定试验,获取传感器的标定数据,得到传感器的转换系数和非线性误差。开展传感器的环境与可靠性试验验证。结果 传感器的转换系数具有较高的一致性,系数最大为0.342,最小为0.335,偏差为2.05%,试验传感器最大非线性误差为1.3%,并通过了9项环境试验与2.56个循环(共1 980 h)的可靠性试验考核。结论 提出的标定方法适用,传感器可承受海洋环境条件中温度、湿度和盐度的长期作用,满足实船监测需求。     

便携式烟气SO_2监测仪的原理与应用

便携式烟气ＳＯ２ 监测仪目前已经成为锅炉污染源监测的主要手段。从仪器的原理入手,通过介绍仪器的结构和工作过程,对仪器应用中的标定、校准、现场测试的步骤给以介绍,并给出了仪器法和碘量法的对比测试结果。     

臭氧监测仪实验室校准及稳定性测试

以国内监测系统在用的臭氧校准仪为二级传递标准对臭氧监测仪开展了实验室校准,通过计算单次校准所得校准曲线的斜率和截距,符合中国相关标准中关于臭氧监测仪的校准指标:多点校准所得校准曲线的斜率为0.95~1.05,截距为-5~5 nmol/mol。进一步对2台臭氧监测仪进行了稳定性测试,12个月内臭氧监测仪的斜率变化为0.976 05~1.008 42,截距变化为-0.669 00~0.577 93 nmol/mol,臭氧监测仪的斜率、截距均符合臭氧监测仪校准指标的要求。稳定性测试表明,TF 49i型臭氧监测仪和EC 9810型臭氧监测仪经校准后均可用于实验室内臭氧标准传递比对工作。实验中臭氧监测仪更换臭氧涤除器、仪器零件后校准曲线的斜率均有明显变化,建议更换耗材后需采用高浓度臭氧对臭氧监测仪进行饱和并再次校准。     

What is a static head measurement? Evaluating structural error and implications for regional groundwater modeling

Most groundwater modelers avoid using static heads measured from active production wells because they can introduce a bias into model calibration. However, in the deep confined Cambrian-Ordovician Sandstone Aquifer System in the Central Midcontinent of North America, dedicated observation wells are sparse and remote from areas of most concentrated pumping. As a result, in areas where drawdown is the greatest and modeling is most needed, only static heads from production wells are available for calibration. This paper evaluates two leading sources of discrepancies in using production well data, spatial and temporal structural error (S.E.). A simple Theis solution is used to evaluate the potential magnitude of spatial S.E. when calibrating a regional MODFLOW model with coarse cell resolution. Despite theoretical analyses indicating that spatial S.E. could be significant, statistical analysis of the model results suggests that temporal S.E. is dominant. Long (ranging over decades) or frequent (monthly) head datasets are key in understanding temporal S.E., to better capture water-level variability. In this study, the range in static head observations impacted estimates of the remaining time a well could extract water from the aquifer by 0.1 to 16.0 years. This uncertainty in future water supply is highly relevant to stakeholders and must be assessed in hydrographs depicting risk.     

中国地区太阳分光辐射观测网的建立与仪器标定

大规模的太阳分光地基联网观测不但能够直接为该项研究提供基础数据,同时也可为卫星遥感提供地表订正.利用性能优越的LED型太阳光度计,依托中国生态研究网络(CERN)分布在中国各地的观测站,建立了标准的太阳分光辐射观测网.利用Langley定标法结合量值传递定标法对观测网所有光度计的标定方法及误差分析表明,不同光度计间的同步观测结果(相对标准偏差小于3%)以及与CIMEL光度计的观测结果间(相对偏差小于5%)有很好的一致性,证实了观测结果的准确性以及该类型光度计及其观测网的稳定性和可靠性.     

Application of SWAT with and without Variable Source Area Hydrology to a Large Watershed

In this study, two different versions of the Soil and Water Assessment Tool (SWAT) model were used to simulate the hydrology and biogeochemical response of the Cannonsville Reservoir watershed, in New York. The first version distributes overland flow in ways that are consistent with variable source area (VSA) hydrology driven by saturation excess runoff, whereas the second version is the standard version of SWAT. These two models were each calibrated for streamflow (Flow), particulate phosphorus (PP), total dissolved phosphorus (TDP), and sediment (Sed) against measured data from the 1,200 km² Cannonsville watershed. The standard version of the model yielded an r² between the measured and simulated data of 0.85, 0.73, 0.70, and 0.72 for Flow, Sed, TDP, and PP, respectively. The VSA version yielded an r² of 0.84, 0.69, 0.72, and 0.53 for Flow, Sed, TDP, and PP, respectively. The two models were then used to determine the maximum upper bound on the reduction in phosphorus loading by removing all of the corn in the watershed. The average reductions between the two models were 65 and 37% for PP and TDP, respectively. The VSA version was also used to estimate the effect of moving corn land in the watershed from the wettest, most runoff prone areas to the driest, least runoff prone areas, which cannot be done directly with the standard SWAT model.     

Revisiting Kappa to account for change in the accuracy assessment of land-use change models

Land-use change models are typically calibrated to reproduce known historic changes. Calibration results can then be assessed by comparing two datasets: the simulated land-use map and the actual land-use map at the same time. A common method for this is the Kappa statistic, which expresses the agreement between two categorical datasets corrected for the expected agreement. This expected agreement is based on a stochastic model of random allocation given the distribution of class sizes. However, when a model starts from an initial land-use map and makes changes to it, that stochastic model does not pose a meaningful reference level. This paper introduces K_Simulation, a statistic that is identical in form to the Kappa statistic but instead applies a more appropriate stochastic model of random allocation of class transitions relative to the initial map. The new method is illustrated on a simple example and then the results of the Kappa statistic and K_Simulation are compared using the results of a land-use model. It is found that only K_Simulation truly tests models in their capacity to explain land-use changes over time, and unlike Kappa it does not inflate results for simulations where little change takes place over time.     

便携式智能电能表功耗测量仪设计、校准与应用

针对目前智能电能表功耗检测困难,设计了一种便携式功耗测量仪。分析了功耗测量仪的总体结构和关键技术,给出了仪器的校准数据及仪器应用方法。经实践证明,该功耗测量仪在测量精度和实用性上表现良好。     

A hierarchical analysis of terrestrial ecosystem model Biome-BGC: Equilibrium analysis and model calibration

The increasing complexity of ecosystem models represents a major difficulty in tuning model parameters and analyzing simulated results. To address this problem, this study develops a hierarchical scheme that simplifies the Biome-BGC model into three functionally cascaded tiers and analyzes them sequentially. The first-tier model focuses on leaf-level ecophysiological processes; it simulates evapotranspiration and photosynthesis with prescribed leaf area index (LAI). The restriction on LAI is then lifted in the following two model tiers, which analyze how carbon and nitrogen is cycled at the whole-plant level (the second tier) and in all litter/soil pools (the third tier) to dynamically support the prescribed canopy. In particular, this study analyzes the steady state of these two model tiers by a set of equilibrium equations that are derived from Biome-BGC algorithms and are based on the principle of mass balance. Instead of spinning-up the model for thousands of climate years, these equations are able to estimate carbon/nitrogen stocks and fluxes of the target (steady-state) ecosystem directly from the results obtained by the first-tier model. The model hierarchy is examined with model experiments at four AmeriFlux sites. The results indicate that the proposed scheme can effectively calibrate Biome-BGC to simulate observed fluxes of evapotranspiration and photosynthesis; and the carbon/nitrogen stocks estimated by the equilibrium analysis approach are highly consistent with the results of model simulations. Therefore, the scheme developed in this study may serve as a practical guide to calibrate/analyze Biome-BGC; it also provides an efficient way to solve the problem of model spin-up, especially for applications over large regions. The same methodology may help analyze other similar ecosystem models as well.     

FHD-1型质子磁力仪的改进与完善

根据FHD 1型质子磁力仪在实际使用过程中存在的一些问题 ,以及一些用户提出的建议和要求 ,对FHD 1型质子磁力仪的实时时钟、标定方法、通用性与适应性、抗干扰能力方面进行了改进和完善 ,本文对此作介绍。