东北地区大豆干旱指标构建及时空特征分析

[目的]东北地区大豆干旱严重,构建基于灾变过程的东北地区大豆干旱等级指标,分析研究区域大豆干旱时空分布特征,对大豆干旱灾害进行实时监测预警、区域防旱减灾具有重要意义。[方法]文章利用1961—2020年东北地区101个气象站点逐日气象资料、45个农业气象站的大豆发育期资料以及大豆历史灾情资料,通过历史灾情资料反演,基于水分盈亏指数并进行累计概率分布转换获得大豆干旱样本序列,采用K-S分布拟合检验拟合样本序列概率分布,通过t分布区间估计法确定指标等级阈值,并进行验证。在此基础上,分析大豆干旱时空变化特征。[结果](1)将大豆水分盈亏指数CD_50,i=0.56作为大豆干旱过程初始判别值,以CD_50,i≥0.56干旱过程持续日数(D)为主导因子,以CD_50,i≥0.56逐日累加值(SDI)为辅助因子,构建了基于日尺度气象资料的东北地区大豆干旱等级指标,实现了干旱的动态化判识,指标验证结果显示与灾情记录等级完全符合的样本占全部样本的82.4%。(2)东北地区大豆每站平均总干旱频次最高的年份为1989年,达到1.51次/站,其次是...     

农村住宅抗震安全性问题

分析了地震中农村住宅的破坏原因和不符合抗震设防要求的方面,提出了农村自建住宅的抗震设防措施,对村镇新建住宅的建设有一定的借鉴意义.     

Insurgent Building: Emerging Spatial Politics in the Bedouin–State Conflict in Israel

In the conflict between Bedouin representatives and government authorities in the southern Israeli Negev, the term ‘insurgent building’ refers to the construction of buildings erected in the full expectation that they will be demolished by the Israeli police shortly thereafter. This article analyses how insurgent building is employed as a spatial practice by emerging political actors to claim contested Bedouin landownership. Importantly, insurgent building relies on the ability of media and advocacy organizations to mobilize behind the issue. Most of the relevant scholarship takes the interpretative categories advanced by these actors at face value. Following anthropological debates regarding objectification and categorization, I examine the context of a specific case of insurgent building. Emerging political actors who employ insurgent building often rely on predefined ethnic categories and clear‐cut people–state polarities. This case demonstrates the need for a more differentiated understanding of multilayered local dynamics than the one offered by mainstream linear interpretations. At a more abstract level, political actors contribute to the reproduction of the very categories against which they mobilize.     

电动机综合控制技术

本文的电动机控制技术,是以"变相电阻"为基础,以控制电动机转子电流为核心,包括电动机的启动、调速技术。通过斩波技术,实现转子阻抗的变化,控制转子电流。     

施工中混凝土小型空心砌块墙体抗裂、抗渗能力的质量保证

相对于黏土砖而言,混凝土小型空心砌块属于一种新型建筑材料。在工程实践中,随着混凝土小型空心砌块墙体建筑的增多,混凝土小型空心砌块暴露出一些问题,如容易产生墙体裂缝及雨水渗漏等。文章就施工中混凝土小型空心砌块墙体的抗裂、抗渗能力的质量保证进行了阐述。     

叠合箱受弯性能的试验研究与分析

混凝土叠合箱网梁楼盖是一种新型的楼盖形式,是由小型预制构件(混凝土叠合箱)与现浇混凝土肋梁结合成具有连续箱型截面的整体结构。本文通过对网梁楼盖的3块构件进行抗弯性能试验,得到了楼盖在受弯时的破坏机理,给出了截面抗弯承载力计算方法,为此种新的构件形式的工程应用提供了依据。     

鸢尾属植物抗旱生理指标的测定

利用聚乙二醇(PEG-6000)以10%、20%、30%三个浓度,将四个品种鸢尾植株进行浸根处理,作为模拟土壤干旱胁迫。测定结果表明:马蔺具有较强的抗旱性。质膜透、MDA含量和SOD活性含量是鸢尾属植物重要的抗旱生理指标。     

论我国抗旱立法的完善

旱灾一直是我国的主要自然灾害之一,它影响粮食安全、饮用水安全、生态安全。面对大旱,我们必须深刻反思我国现有抗旱立法工作的不足之处,并通过加强防灾减灾与水资源管理方面立法,完善《森林法》的内容,加快制定农业保险法、农田水利法等农业立法,使我国抗旱工作有法可依,提高我国应对旱灾的能力。     

Valuing GM technologies using real options: the case of drought tolerant wheat in Australia

ABSTRACT

In this article we seek to estimate the value of a partially-developed crop technology from the perspective of the firm developing the technology. Firms need this value estimation to decide whether their technology will earn a sufficient return in the market to justify investing in it. However, determining the (ex-ante) value of the technology before it is commercialised is challenging as the technology is not yet in the market and hence the demand function has not yet been defined. An alternative valuation method is required. We use risk premiums, Monte Carlo simulation and real options analysis and we demonstrate this combination of valuation tools on wheat that is currently being developed in Australia to be drought tolerant. The results indicate that this drought tolerant wheat variety is likely to be adopted by farmers in most regions and has a pre-commercialisation value that justifies continued investment in its development. We also identified South Australia as a region in which the new variety would not be sufficiently valuable to farmers to see them adopt it and we consider possible explanations for this outcome.     

A tactical retreat? Conceptualising the dynamics of European grocery retail divestment from East Asia

The internationalisation of the firm is a highly dynamic process, in which periods of investment and expansion intermingle with periods of divestment and retrenchment. Academic research to date has focused on identifying the reasons for and the processes of divestment. Empirical studies either evidence generic pressures or provide case studies of specific incidents. There few longitudinal studies of international divestment, consequently the dynamic interactions between host market, home market and firm level factors, and how the institutional context changes over time is underplayed. This paper seeks to rectify this gap in our understanding.We explore the rationale and evolving dynamics of European grocery retail divestment in East Asia over a thirty year period. Taking an inductive approach and drawing on analysis of contemporary narratives drawn from company documentation, trade journals, newsfeeds and market reports, three phases can be identified characterised by specific factors and combinations of factors which intersect to provide the key pressures and stimuli for divestment. We conclude that at different time periods, different internal and external contextual influences manifest themselves through different priorities within the firm’s strategy – marked by a switch from local (host) market, to regional, to global firm-centric considerations. Longitudinal analyses allow a greater recognition of this dynamic interplay of factors, and the changes in these relationships, and provides a more nuanced understanding of the international divestment process.