Continuous simulation for computing design hydrographs for water structures

The contribution discusses the problems with modelling design floods for water structures. The statistical extrapolations of observed flood series of, for example, 80 years “only” to the annual exceedance probability AEP = 0.01 is difficult due to the large variability in extreme values. For large dams, however, the AEP = 0.001 or 0.0001 is required. Most of the uncertainties in hydrological modelling are epistemic (uncertainties in model structure, model parameters, inputs, calibration data, and in measurements) and moreover some measurements can be disinformative. With powerful computers, it is now possible to produce very long series (100 to100,000 years in hourly time step) using precipitation and temperatures computed with a weather model. Within the framework of the Generalised Likelihood Uncertainty Estimation (GLUE) many (thousands) of such continuous simulations are produced and compared to the observed historical data. According to Keith Beven's Manifesto for the equifinality thesis the differences between modelled and observed values should not be larger than some limits of acceptability based on what is known about errors in the input and output observations used for model evaluation (e.g., for flow the current metering data are used). The unacceptable realisations are rejected. We have been working with the frequency version of TOPMODEL in various versions according to the unique characteristics of each catchment. Design hydrographs for water structures are then extracted from the acceptable realisations. The continuous simulation with uncertainty estimation seems nowadays the most promising method of computing design hydrographs for important water structures, even if issues associated with epistemic uncertainty of model assumptions remain.     

震源性质的时频分析与事件识别

应用时频分析技术研究了近年来发生在朝鲜半岛的核爆炸、化学爆炸与天然地震事件的识别问题,计算了上述三者的瞬时频率、瞬时振幅谱与群延迟等多项参数,提出地震与爆炸的识别指标.初步研究结果表明,对较大事件,上述三者来自震源的激发频率信息有明显差异性,核爆炸源激发的频率明显高于地震,化学爆炸最低.特别是,这些信息指标对于识别小当...     

A framework for a seismic risk model for Greater Cairo

Following the adverse effects caused by the moderate M_s 5.4 event of October 1992, the need to model the risk from earthquakes occurring in or near Cairo was shown to be an essential tool to offset this threat in the future. To provide the necessary elements for a risk model, this paper describes a methodology for developing a ground-shaking model as well as an inventory database for the city. In the first part, a scheme is followed to integrate data on geological structures, seismic sources, seismicity and surface soil conditions to build-up an event-based hazard model. In the second part, a brief review of the history of seismic provisions in Egyptian codes is presented, and a detailed assessment of local maps and information is supplemented by results from street surveys to obtain building stock data and geographical resolutions. On the basis of these studies, the city is divided into a number of census-tracts, or geo-codes, of classified building and soil characteristics, representing a fundamental step towards the development of a full loss model.     

A method for estimating specimen tangent stiffness for hybrid simulation

Researchers have long recognized the importance and potential benefits of utilizing the tangent stiffness matrix of a test specimen in hybrid simulations employing implicit and mixed‐integration schemes. However, the computation of the tangent stiffness matrix during testing has proved to be challenging, particularly for test specimens with more than one degree of freedom (dof). This paper presents a new methodology that is more straightforward and simpler than existing techniques for computing the tangent stiffness matrix of a multi‐dof test specimen. The proposed method is combined with the operator‐splitting method (OSM), and the capabilities, advantages and limitations of the new formulation are demonstrated through several examples. The accuracy, stability, and error propagation characteristics of the modified OSM are also studied theoretically as well as numerically. The research results show that the proposed algorithm provides results that are better than those produced via the regular OSM alone, especially for damped structures undergoing highly inelastic behavior during testing. Copyright © 2008 John Wiley & Sons, Ltd.     

Selection and criteria for biological indicator species for Arctic monitoring

The estuarine ecosystems are considered as key objects in the Arctic monitoring. Crustacean Saduria entomon, bivalve Portlandia aestuariorum and Cyrtodaria curriana, whitefish Coregonus muksun, C. autumnalis and C. sardinella sardinella and sculpin Triglopsis polaris (= Myoxocephalus quadricornis) are proposed for monitoring of Arctic estuaries. Review of AMAP list of species was carried out. Some species, as included in the World and National ‘Red Books’ and thus being under legislation (polar bear, atlantic and Laptev sea subspecies of walrus, falcon Falco rusticolus) must be left out of the list of species-monitors. The same is applied as in the case of species which often feed on human waste (glaucous gull, fulmar). Instead of using the rare and valuable carnivorous species, appropriately their prey is used as monitors.     

一种Timoshenko裂纹梁的静力挠度分析方法

建立了一种Timoshenko裂纹梁的分析模型并且获得了闭合形式的挠度解析解。首先,在一致梁的理论框架下,通过引入δ函数模拟裂纹导致的局部柔度,建立用广义函数表示的Timoshenko裂纹梁的微分控制方程,进而得到挠度的闭合形式的解答;其次,根据线弹性断裂力学理论,利用转角及挠度突变与局部柔度系数的关系,建立Timoshenko裂纹梁的模型参数与裂纹深度的显式表示;最后,通过对裂纹深度与挠度、转角和曲率间关系的分析,总结了结构响应的损伤敏感性及其特征,并且通过与引入裂纹奇异单元的有限元结果进行比较,验证了本文所建分析模型及求解方法的正确性。研究结果表明,本文所建立的Timoshenko裂纹梁的分析模型,具有较高的计算精度和效率,在结构模型修正和损伤识别中具有良好的应用前景。     

A method for tuning tuned mass dampers for seismic applications

This paper studies tuned mass dampers (TMDs) resulting in high modal damping for mechanical systems incorporating such devices for the purpose of seismic response reduction. Focusing on the determination of damping and tuning, the proposed methodology identifies a point of multiplicity of complex eigenvalues and eigenvectors, resulting in different parameters for TMDs according to their location with respect to such multiplicity condition. It is shown that significant equal modal damping and average modal damping can be induced by properly tuning highly damped TMDs, obtaining parameters intrinsic to the mechanical systems, and excitation independent. Further, it is shown that the methodology yields, as particular cases, two proposals by others using TMDs for the same purpose of seismic response abatement. Copyright © 2012 John Wiley & Sons, Ltd.     

Developing methods for bioidentification of xenobiotics for water quality assessment

The role of bioassay in the pollution control system for water bodies is considered. Studies of the mechanisms of toxic impact of various chemical compounds on aquatic organisms were used to develop a bioindication method to give an integral estimate of water toxicity and determine some classes of chemical pollutants. The results of application of such methods to assessing water quality in Lake Ladoga are given.     

星云湖流域综合治理规划方案研究

富营养化加重,水土流失严重,水资源缺乏是星云湖流面临的主要环境问题,针对于此,本文提出了以控制氮磷为重点,分阶段,分区域实行综合治理的工程规划方案,共计有工业点源治理,城镇生活污水处理、农业非点源治理,流域生态系统恢复等11项工程方案,总投资为4．46亿元。     

Mechanisms for the prevention of marine bioinvasions for better biosecurity

Biosecurity management allows countries to meet a number of international obligations and provides some protection from potential degradation of environmental, economic, social and cultural values. Ocean governance relies on the precepts of ecologically sustainable development to manage the multiple uses in the coastal zone. The increasing reliance on aquaculture to provide food security and economic development has led to an increase in the use of non-native target species grown as food sources. Increased economic activity has led to shifting trade patterns and increased efficiencies in vessels with the resulting increase in the number of introduced marine species via ballast water and hull fouling. Herein we review the different marine biosecurity strategies and legislation that have been implemented internationally and locally that aid in preventing and managing introduced marine species, with some attention to Australia and New Zealand as examples. Typical tools being used include quarantine, Import Health Standards, voluntary cleaning guidelines, and risk assessment, all of which aim to prevent introductions.     

Telescopes for Schools

Helen Walker reports on the success of the IYA2009 initiative to get telescopes into schools – and to provide a DVD to help teachers put them to good use.     

Design considerations for using Distributed Acoustic Sensing for cross-well seismics: A case study for CO2 storage

Downhole monitoring with fibre-optic Distributed Acoustic Sensing (DAS) systems offers unprecedented spatial resolution. At the same time, costs are reduced since repeated wireline surveys can be replaced by the permanent installation of comparatively cheap fibre cables. However, the single component nature of fibre data requires novel approaches when designing a monitoring project such as cross-well seismics. At the example of the shallow CO₂ injection test site in Svelvik, Norway, we model the evolution of velocity changes during CO₂ injection based on rock physics theory. Different cross-well seismic design scenarios are then considered to evaluate the best design and the limits of this method to detect containment breach. We present a series of evaluation tools to compare the effect of different well spacings for cross-well seismic tomography. In addition to travel-times, we also consider characteristic amplitude changes along the fibre unique to DAS strain measurements, which might add a constraint to the inversion. We also compare the effect of using helical fibres instead of classical straight fibres. We thus present a toolbox to evaluate and compare different monitoring design options for fibre optic downhole installations for cross-well monitoring.     

Temporal-moment matching for truncated breakthrough curves for step or step-pulse injection

The method of temporal moments is an efficient approach for analyzing breakthrough curves (BTCs). By matching the moments of the BTCs computed through parametric transfer-function models or one-dimensional transport models to those of the data, one can estimate the parameters characterizing the transfer function or apparent transport parameters. The classical method of moments presumes infinite duration. However, the measurement of BTCs is usually terminated prematurely, before the concentration has reached zero. Unless this truncation of the BTCs has been taken into account, the estimates of the parameters may be in error. Truncated measured BTCs are sometimes extrapolated assuming exponential decay. In this study, we use the concept of moments of the truncated impulse–response function [Jawitz JW. Moments of truncated continuous univariate distributions. Adv Water Res 2004;27:269–81] in the analysis of truncated BTCs corresponding to the commonly encountered step and step-pulse injection modes. The method is straightforward, based on the relation, which we derive, between truncated moments of the impulse–response function and the measured BTC. It is practical to apply and does not require the extrapolation of the measured BTC. The method is also accurate. In a numerical study we discuss how short a step-pulse injection may be so that we can approximate it as instantaneous. Finally, we apply the method to the analysis of a field-scale tracer test.     

Methodology for the development of analytical fragility curves for retrofitted bridges

Fragility curves for retrofitted bridges indicate the influence of various retrofit measures on the probability of achieving specified levels of damage. This paper presents an analytical methodology for developing fragility curves for classes of retrofitted bridge systems. The approach captures the impact of retrofit on the vulnerability of multiple components, which to date has not been adequately addressed, and results in a comparison of the system fragility before and after the application of different retrofit measures. Details presented include analytical modeling, uncertainty treatment, impact of retrofit on demand models, capacity estimates, and component and system fragility curves. The findings indicate the importance of evaluating the impact of retrofit not only on the targeted response quantity and component vulnerability but also on the overall bridge fragility. As illustrated by the case study of a retrofitted multi‐span continuous (MSC) concrete girder bridge class, a given retrofit measure may have a positive impact on some components, yet no impact or a negative impact on other critical components. Consideration of the fragility based only on individual retrofitted components, without regard for the system, may lead to over‐estimation or under‐estimation of the impact on the bridge fragility. The proposed methodology provides an opportunity to effectively compare the fragility of the MSC concrete bridge retrofit with a range of different retrofit measures. The most effective retrofit in reducing probable damage for a given intensity is a function of the damage state of interest. Copyright © 2008 John Wiley & Sons, Ltd.     

大震应急的地震趋势分析系统

本系统是为震情出现后辅助分析人员及时进行地震发展趋势估计所设计的一套实用程序系统，它以地震序列分析方法为基础，结合计算机软件技术，数据库技术，快速，灵活地给出地震序列的各种时序曲线和数值特征值，平面和剖面地震分布图，并可根据已有的经验关系，专家知识，对地震发展趋势作出估计。     

A decision-theory methodology for the selection of buildings for strong-motion instrumentation

Current projections indicate that six buildings per year will continue to be instrumented under the California Strong-Motion Instrumentation Program for the next several decades. In order to select these buildings systematically for instrumentation, we have developed a methodology that incorporates the fundamental elements of decision theory. These elements include an identification of the types of buildings that should be instrumented, a definition of the expected severity of ground shaking at each possible building site along with the probability of occurrence, and a quantification of the relative value of obtaining a building-response record for each building type. Using this information, we can apply decision theory to calculate the expected utility (degree of preference) of instrumenting buildings of a particular type at various sites. The sites are then ranked in order of preference for each building type. This procedure, developed for the California Strong-Motion Instrumentation Program, can be extended to instrumentation programs in other areas.     

The Technological Conditions for the Development of Acinetobacter for Phosphorus Removal

A simplified suspended growth integrated system with an anaerobic zone in front of the aerobic one was used for the development of the bacterium Acinetobacter for phosphorus removal. The pilot plant experimental equipment was built at the Prague municipal works. The tests were carried out on a comparative basis, the control system was operated as a completely mixed activated sludge process. In the integrated system a to phosphate removal of 80 to 86% was achieved only in a biological way. In the control system, there was no development of Acinetobacter and the biological phosphate removal was only 5%. To rise it to the extent comparative with the integrated system, high doses of ferric chloride for a simultaneous precipitation of phosphate were required. The results obtained showed that the strictly biological process in the integrated system could meet normal practice requirements, even though it is not able to compete with the simultaneous phosphate precipitation using high coagulant dosages as for as the attainable efficiency and higher values of the sludge index are concerned.     

Deterministic sensitivity analysis for a model for flow in porous media

A deterministic method for sensitivity analysis is developed and applied to a mathematical model for the simulation of flow in porous media. The method is based on the singular value decomposition (SVD) of the Jacobian matrix of the model. It is a local approach to sensitivity analysis providing a hierarchical classification of the directions in both the input space and of those in the output space reflecting the degree of sensitiveness of the latter to the former. Its low computational cost, in comparison with that of statistical approaches, allows the study of the variability of the results of the sensitivity analysis due to the variations of the input parameters of the model, and thus it can provide a quality criterion for the validity of more classical probabilistic global approaches. For the example treated here, however, this variability is weak, and deterministic and statistical methods yield similar sensitivity results.     

Original technologies for proven performances for the new LCPC earthquake simulator

The European Quaker project has been a powerful opportunity to accelerate the development of the ability to carry out earthquake simulations at reduced scale in the centrifuge in LCPC—France. This paper summarizes the main original technologies of this simulator. The quality of the checked performances is demonstrated in terms of ability to perform since earthquakes as well as to simulate scaled records of real earthquakes. The consistancy of the results is presented in the time and in the frequency domains.