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21.
治导线规划是河道整治规划吕的一个主要内容。一般平原河流应考虑中水河床和洪水河床两种情况,山区河道只考虑洪水河床。河道整治宽度确定之后,治导线基准点的确定是河道两岸十分关心的问题,应遵循一些原则。在治导线连接上,应按中小河床与洪水河道采用不同线型。  相似文献   
22.
总结了江西省铅山县乡镇防汛抗旱指挥部办公室建设存在的主要问题,对强化该县防汛抗旱指挥部办公室能力建设提出了建议.  相似文献   
23.
杨光煦 《人民长江》1999,30(9):13-15
长江中下游堤防多位于由表层弱透水层及下卧透水层组成的双层地基上,堤防及其地基、边滩在汛期出现的险情有散浸,管涌,流土、接触冲刷引起的渗水流砂、漏洞,穿堤建筑物渗漏,滑坡,崩岸,溢溢等。  相似文献   
24.
本文基于鄱阳湖洪水特点,选取特定洪水特征指标,利用数理统计方法分析鄱阳湖洪水特征指标的趋势性、突变性和周期性,并分析演变特征和驱动因素,得到结论如下:1)未来高洪可能性仍然较大,未来6~10a鄱阳湖年最高水位仍处于丰水期;2)洪水在年内分配发生较大改变,变化过程从“矮胖型”向相对“尖瘦型”演变,水量在年内更加集中化;3)高洪持续天数显著增加,19.00m以上的高水位维持时间平均每10a延长2.2d;4)年最高水位及年平均水位周期性变化主要受“五河”入湖周期性变化所控制,同时会受到其他因素影响而改变原有周期性变化规律,年最高水位具有5a为第一主周期,40~49a为第二主周期的变化规律。  相似文献   
25.
FY型粮食装卸机的设计与计算   总被引:1,自引:0,他引:1  
介绍了FY 型粮食装卸机的工作特性和具有粮食分级功能的中间分离仓;可自动调节补风量大小的喂料器;可伸缩、弯转的组合风管等主要部件的结构、特点及主要性能参数的计算方法。  相似文献   
26.
The quest for authenticity in dining experiences has become increasingly important. This paper explores authenticity dimensions that are of value to customers in dining experiences, and by that gains a multi-dimensional understanding of authenticity in this context. Following an integrated learning approach using text mining and classification techniques, this paper explores and confirms different dimensions of authenticity by identifying and classifying authenticity judgements in online restaurant reviews. The results suggest that authenticity is a multi-dimensional concept encompassing Authenticity of the Other, Authenticity of the Producer, and Authenticity of the Self as first-level dimensions. Additionally, besides historical and categorical authenticity which have been previously explored in the literature, a new type of authenticity - Deviated Authenticity - emerged as a second-level dimension falling under Authenticity of the Other. This paper enhances existing conceptualisations of authenticity and establishes avenues for exploring the multi-dimensionality of other consumer research concepts using user-generated content.  相似文献   
27.
Characterization and construction of optimal designs using the familiar optimality criteria, for example A-, D- and E-optimality are well studied in the literature. However the study of the Distance Optimality (DS-) criterion introduced by Sinha (1970) has very recently drawn attention of researchers. In the present article, we consider the singularly estimable full rank problem of estimating the full set of elementary treatment contrasts using the DS optimality criterion in the set up of a one way ANOVA model. Using a limit argument it turns out that a CRD in which difference between any two allocation numbers is at the most unity is uniquely DS-optimal. Acknowledgement. We are thankful to Prof. B. K. Sinha for suggesting the problem to us and many helpful discussions with him. We are also thankful to the referees for drawing our attention to the reference of Bischoff (1995) and many helpful comments.  相似文献   
28.
We provide specific qualifications in order that Kuhn–Tucker type Euler equations and transversality conditions at infinity hold in stochastic equilibrium models with heterogeneous agents and where assets are traded in sequential markets. It is not assumed that uncertainty is modeled as an event-tree structure or that preferences are necessarily bounded. We also describe an important class of preferences based on bounded relative risk aversion which yields relevant simplifications. Our results are used to establish conditions that rule out asset pricing bubbles. Specific examples of economies with bubbles are also discussed. Received: 28 January 2002 / Accepted: 19 July 2002 We are grateful to the editor and an anonymous referee for their valuable comments. This research was partially supported by MURST (Italy), National Group on “Nonlinear Dynamics and Stochastic Models in Economics and Finance”.  相似文献   
29.
Housing fever is a popular term to describe an overheated housing market or housing price bubble. Like other financial asset bubbles, housing fever can inflict harm on the real economy, as indeed the U.S. housing bubble did in the period following 2006 leading up to the general financial crisis and great recession. One contribution that econometricians can make to minimize the harm created by a housing bubble is to provide a quantitative “thermometer” for diagnosing ongoing housing fever. Early diagnosis can enable prompt and effective policy action that reduces long-term damage to the real economy. This paper provides a selective review of the relevant literature on econometric methods for identifying housing bubbles together with some new methods of research and an empirical application. We first present a technical definition of a housing bubble that facilitates empirical work and discuss significant difficulties encountered in practical work and the solutions that have been proposed in the past literature. A major challenge in all econometric identification procedures is to assess prices in relation to fundamentals, which requires measurement of fundamentals. One solution to address this challenge is to estimate the fundamental component from an underlying structural relationship involving measurable variables. A second aim of the paper is to improve the estimation accuracy of fundamentals by means of an easy-to-implement reduced-form approach. Since many of the relevant variables that determine fundamentals are nonstationary and interdependent we use the endogenous instrumental variable based method (IVX) to estimate the reduced-form model to reduce the finite sample bias which arises from highly persistent regressors and endogeneity. The recursive evolving test proposed by Phillips, Shi, and Yu (PSY) is applied to the estimated nonfundamental component for the identification of speculative bubbles. The new bubble test developed here is referred to as PSY-IVX. An empirical application to the eight Australian capital city housing markets over the period 1999–2017 shows that bubble testing results are sensitive to different ways of controlling for fundamentals and highlights the importance of accurate estimation of these housing market fundamentals.  相似文献   
30.
We examine the effect of research and development (R&D) on long-term economic growth using the Bayesian model averaging (BMA) to deal rigorously with model uncertainty. Previous empirical studies, which applied BMA, investigated the effect of dozens of regressors on long-term growth, but they did not examine the effect of R&D due to data unavailability. We extend these studies by proposing to capture the investment in R&D by the number of Nobel prizes in science. Using our indicator, the estimates show that R&D exerts a positive effect on long-term growth. This result is robust to many different parameter and model prior structures as well as to alternative definitions of R&D indicator.  相似文献   
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