Weighing the importance of model uncertainty against parameter uncertainty in earthquake loss assessments

Epistemic uncertainties can be classified into two major categories: parameter and model. While the first one stems from the difficulties in estimating the values of input model parameters, the second comes from the difficulties in selecting the appropriate type of model. Investigating their combined effects and ranking each of them in terms of their influence on the predicted losses can be useful in guiding future investigations. In this context, we propose a strategy relying on variance-based global sensitivity analysis, which is demonstrated using an earthquake loss assessment for Pointe-à-Pitre (Guadeloupe, France). For the considered assumptions, we show: that uncertainty of losses would be greatly reduced if all the models could be unambiguously selected; and that the most influential source of uncertainty (whether of parameter or model type) corresponds to the seismic activity group. Finally, a sampling strategy was proposed to test the influence of the experts’ weights on models and on the assumed coefficients of variation of parameter uncertainty. The former influenced the sensitivity measures of the model uncertainties, whereas the latter could completely change the importance rank of the uncertainties associated to the vulnerability assessment step.     

Oblique wave diffraction by a flexible floating structure in the presence of a submerged flexible structure

Expansion formulae associated with the interaction of oblique surface gravity waves with a floating flexible plate in the presence of a submerged horizontal flexible structure are derived using Green’s integral theorem in water of finite and infinite water depths. The associated Green’s functions are derived using the fundamental solution associated with the reduced wave equation. The integral forms of the Green’s functions and the velocity potentials are advantageous over the eigenfunction expansion method in situation when the roots of the dispersion relation coalesce. As an application of the expansion formulae, diffraction of oblique waves by a finite floating elastic plate in the presence of a submerged horizontal flexible membrane is investigated in water of finite depth. The accuracy of the numerical computation is demonstrated by analysing the convergence of the complex amplitude of the reflected waves and the energy relation. Effect of the submerged membrane on the diffraction of surface waves is studied by analysing the reflection and transmission coefficients for various parametric values. Further, the derivation of long wave equation under shallow water approximation is derived in a direct manner in the appendix. The concept and methodology can be easily extended to deal with acoustic wave interaction with flexible structures and related problems of mathematical physics and engineering.     

On the modified Taylor constraint

A dynamo driven by motions unaffected by viscous forces is termed magnetostrophic. Although such a model might describe magnetic field generation in Earth’s core well, a magnetostrophic dynamo has not yet been found even though Taylor [Proc. R. Soc. Lond. A 1963, 274, 274–283] devised an apparently viable method of finding one. His method for determining the fluid velocity from the magnetic field and the energy source involved only the evaluation of integrals along lines parallel to the Earth’s axis of rotation and the solution of a second-order ordinary differential equation. It is demonstrated below that an approximate solution of this equation for a broad family of magnetic fields is immediate. Furthermore inertia, which was neglected in Taylor’s theory, is restored here, so that the modified theory includes torsional waves, whose existence in the Earth’s core has been inferred from observations of the length of day. Their theory is reconsidered.     

边缘型地区旅游发展的居民环境认同与旅游支持——以泸沽湖景区为例

边缘型地区旅游开发较晚,因生态环境和经济环境比较脆弱,容易受到来自现代化各种因素的影响,环境认同与边缘型地区旅游发展的支持具有相关性,并且环境认同也会影响居民对旅游影响的态度,进而影响旅游支持度。以泸沽湖为例,采用封闭式问卷调查法与结构式访谈法收集居民环境认同、旅游影响的态度和旅游支持的资料,并对数据进行回归分析。结果发现边缘型地区旅游地居民的环境认同较高,对旅游发展持相对谨慎的态度;边缘型地区居民的旅游支持还取决于居民对旅游积极影响的态度,而不是对消极影响的态度;居民对旅游的文化积极影响关注度略大于旅游经济影响。因此,边缘型地区的旅游发展要避免一些核心地区旅游发展过程中的环境破坏、过度商业化等问题,以环境保护为前提,以旅游利益共享为原则,统筹规划,实现旅游可持续发展。     

瞬变电磁场时域格林函数解

近源时间域电磁场具有信号强、探测深度大、精度高等优点,但传统勘探电磁场理论中偶极子近似在近源会引起较大误差,导致这一优势的发挥受到了制约.开展直接时间域电磁场解析式研究,是解决这一问题的途径之一.本文提出在点电荷微元假设下,引入时域格林函数,求取瞬变电磁场时间域解析解.采用积分运算法,把电磁场阻尼波动方程的求解问题转化为求其格林函数积分形式解的问题;建立辅助路径解决奇点问题,利用复分析中的约当引理、留数定理和广义函数等理论和方法,推导计算出时间域格林函数的时空四重广义积分.得到达朗贝尔方程的直接时域格林函数精确解析式,与传统方法“比拟”出的公式具有相同的形式,验证了本文推导的时域格林函数解析公式的正确性;推导出扩散方程的直接时间域解析解.通过与时变点电荷源时间域的电磁响应近似表达式进行对比,得出本文所推导的公式计算精度较高的结论;建立了全空间回线源瞬变电磁场问题的直接时间域求解公式.为解决全场区瞬变电磁场精细探测直接时域解析问题提供了基础理论.     

Heterogeneous management and conservation perceptions within the gooseneck barnacle co-management system in Asturias (N. Spain)

Stakeholders’ perceptions can influence the success of a fishery. It is important to take these perceptions into account when evaluating the development of a management system and its conservation policies. Structured questionnaires were used to determine fishers’ management and conservation perceptions of the Asturian gooseneck barnacle co-management system. Perceptions were analyzed for the entire fishery and for different socioeconomic factors, these were: location, age, years in the management system, way of access, alternative income sources and income. Fishers’ perceptions varied widely among socioeconomic factors. In fact, a trade-off between management and conservation perceptions was observed for the different categories within each socioeconomic factor, particularly for the years in the management system, location and income factors. Despite the heterogeneity in perceptions, the co-management system has successfully generated a strong conservation ethic in its resource users. Furthermore, as a group, gooseneck barnacle fishers hold positive perceptions on the performance of the management system. When generating management policies, fisheries’ managers must take the heterogeneity of resource users present in the fishery into account. The gooseneck barnacle co-management system demonstrates that even within the same fishery there can be multiple paths to sustainability.     

A transition beyond traditional fisheries: Taiwan's experience with developing fishing tourism

Transforming fisheries into tourism has become a global trend. It arises mostly due to a decline in income generated by traditional fisheries, and fishers thus turn to seek alternatives by engaging in marine tourism activities. Taiwan has practiced this transformation policy for more than two decades, and fishing tourism has developed as a major outcome. This paper aims to investigate Taiwan's experience with developing this activity, with an emphasis on the emerging concerns it faces and anglers’ perception of trip quality and potential management measures. The results show that anglers had a general satisfaction with the service delivered by operators. However, concerns regarding sustainable development of this activity were identified, mostly involving ineffective enforcement of regulations against illegal fishing, conflicts of interest between commercial fishing and recreational fishing, lack of statistics on harvest, improper angler behavior, and competition from yachts. Lastly, management implications for sustainable fishing tourism were discussed, highlighting suggestions to alleviate the concerns, including strengthening management of the harvest, encouraging dialogue between commercial and recreational sectors, enhancing marine environmental stewardship among anglers, and improving coordination of management to create a fair and balanced environment for recreational fishing vessels and yachts.     

Is irrigation water price an effective leverage for water management? An empirical study in the middle reaches of the Heihe River basin

Serious water scarcity, low water-use efficiency, and over-exploitation of underground water have hindered socio-economic development and led to environmental degradation in the Heihe River basin, northwestern China. Price leveraging is an important tool in water demand management, and it is considered to be effective in promoting water conservation and improving water use efficiency on the premise that water demand is elastic. In the present study, we examine whether price is an effective and applicable instrument for restraining the increasing demand for agricultural irrigation water in the middle reaches of the Heihe River basin and how will it affect farmers’ decisions on irrigation and crop structure. Specifically, the price elasticity of agricultural water demand was estimated based on the irrigation water demand function. The results show that the agricultural irrigation water price is statistically significant, but its elasticity is very low under current low water price. Price leverage cannot play a significant role in the context of the current pricing regime and farmers’ response to price increase is intrinsically weak. To create incentives for conserving water and improving irrigation efficiency, price mechanism should be accompanied with clearly defined and legally enforceable water rights, restricted water quota measures, and reform of water authorities and water-user associations. Furthermore, increases of surface irrigation water price may lead to the over-withdrawal of groundwater, consequently, effective groundwater licensing and levying must take place to limit the total volume of groundwater withdrawal. In all, improving irrigation efficiency through better management and the adoption of water-saving technologies is the ultimate way to deal with the challenges facing irrigated agriculture in the middle reaches of the Heihe River basin.     

Smith租差理论与中产阶层化动态演绎

从居民效用与开发商收益视角下,以Smith租差理论为基础,构建多智能体模型,并结合纳什均衡解决居民修缮决策博弈,模拟中产阶层化进程。研究表明:在效用最大时,增加居民收入将降低中产阶层化发生频率。而在利润最大时,开发商资本的投入与中产阶层化发生频率正相关。资本投入越大,中产阶层化发生频率越高。但资本并非万能,当它的投入超出限值时,中产阶层化进程渐趋稳定。提高开发商投资门槛,将强化房地产业的垄断,开发商为获取巨额垄断利润,一方面,他们可能故意提高局部地区的资本化地租,这导致了中产阶层化更快、更多地发生;另一方面,他们在任意区位开发都能获取高额利润,这间接造成中产阶层化程度下降。     

雅安市近地面空气负(氧)离子状况初探

本文基于2010～2011年雅安市气象局进行的“雅安市空气负(氧)离子观测研究”资料,对雅安市近地面空气负(氧)离子状况进行了初步分析.主要结论为:(1)雅安市具有优异的空气负(氧)离子生态资源,城区空气负(氧)离子浓度等级大多数情况都在6级(负离子浓度≥2100个/cm3)以上,近郊的负(氧)离子浓度大多数情况都超过6级,较高时可接近60000个/cm3,风景区的负(氧)离子浓度大多数情况都远远超过6级,较高时≥60000个/cm3,是名符其实的“天府之肺”、“中国的绿色宝石”和“中国生态气候城市”.(2)雅安市境内,空气负(氧)离子浓度的日变化规律通常为7时左右最大,15时左右最低;空气负(氧)离子浓度和天气、相对湿度有较密切的关系,通常的规律为:降雨后的清晨、雷雨后,空气负(氧)离子浓度明显增加;空气负(氧)离子浓度和相对湿度成正相关.(3)和国内已有研究资料的地区比较,雅安市空气负(氧)离子浓度水平在国内为最高地区之一.