保定市主要作物需水量和缺水量特征分析

[目的]对作物需水量及缺水量的研究是了解和合理配置农业灌溉用水的基础,对提高农业用水效率有重大意义。[方法]选取河北省保定市为研究区域,利用Penman-Monteith公式和分段单值平均作物系数法对冬小麦、夏玉米和棉花的作物需水量和缺水量等指标进行计算,通过Mann-Kendall检验法对保定市近60年来的作物需水量和缺水量等的变化趋势进行分析。[结果]3种主要作物的需水量、有效降雨量和缺水量的最大值均出现在作物发育中期;其中除冬小麦的有效降雨量以0.208mm/10年的速率呈不显著性增长趋势外,其他作物的各指标变化则均呈减少趋势;从突变现象来看,夏玉米和棉花的各指标发生明显变化的时期相近,需水量出现明显拐点的时刻在2008年以后,有效降水量在1968年以前和2014年两个时期,缺水量分别在2011年和2012年。[结论]该研究结果为保定市乃至河北省的农作物灌溉效率的提高及水资源规划与管理的完善提供了理论依据,具有一定的现实意义。     

基于遥感蒸散数据的农田灌溉水平评价和设施建设分区研究

[目的]利用遥感蒸散数据快速评价农田年度灌溉水平,及时获取基本农田建设成效,为农田灌溉设施分区建设提供参考。[方法]以黑龙江省海伦市为研究区,MOD16蒸散产品为数据源,计算有效灌溉量、灌溉需水量和作物缺水指数,分别对研究区2013年的旱地和水田灌溉水平进行评价,并将评价结果与农田水利设施作用分值图进行叠加分析,在此基础上进行基本农田灌溉设施建设分区。[结果]2013年海伦市耕地灌溉水平整体较高,区域间建设水平差别较大,可划分为4个级别。其中1级和2级灌溉水平的地块面积比例可达78.06%,地域分布上看,北部、西部、中部乡镇灌溉水平较高,东南部乡镇灌溉水平相对较低。叠加得出8种组合类型,分为设施修建型、设施提升型和设施维护型3种分区类型。[结论]研究为高标准农田建设提供了更详细的农田灌溉水平评价方法和更具差别化的农田灌溉设施建设策略。     

The Effects of Search-Related and Purchase-Related Mobile App Additions on Retailers’ Shareholder Wealth: The Roles of Firm Size,Product Category,and Customer Segment

Mobile channel additions have been shown to increase consumer-brand relationships, brand satisfaction towards and overall purchasing from a retailer, but what is less apparent is whether shareholders are fully rewarded for retailers’ mobile channel additions. Results from an event study on 115 announcements relating to mobile app additions of publicly traded U.S. retail firms between 2009 and 2016 indicate that the stock market responds generally positively to mobile app additions, but specifically to the two mobile app addition types. Stock market responses to search-related and purchase-related app additions are moderated by firm size, product category, and target customer age. For announcements of search-related apps, the market responds more positively to product retailers than to service retailers, and to small firms than large ones. For announcements of purchase-related apps, the market responds less positively to firms that target younger customers than firms who do not especially target them.     

Sensitive Survey Questions: Measuring Attitudes Regarding Female Genital Cutting Through a List Experiment

Potential bias in survey responses is higher if sensitive outcomes are measured. This study analyses attitudes towards female genital cutting (FGC) in Ethiopia. A list experiment is designed to elicit truthful answers about FGC support and compares these outcomes with the answers given to a direct question. Our results confirm that the average bias is substantial as answers to direct questions underestimate the FGC support by about 10 percentage points. Moreover, our results provide suggestive but not statistically significant evidence that this bias is more pronounced among uneducated women and women targeted by an NGO intervention (not randomly assigned).     

Assessing models of individual equity option prices

Review of Quantitative Finance and Accounting - This study sheds light on risk exposures of cooperative banks in Austria, Germany and Italy. We investigate how major risk elements of banks in these...     

How Owners Matter? An Examination of Ownership Type in Corporate Disaster Relief Giving

Little research has investigated the effect of ownership identity (or type) and corporate philanthropy experience on giving. In this research, relying on legitimacy theory, we first assess the effect of ownership identity on corporate philanthropy (CP) in the context of the 2008 earthquake in China. Then we explore moderation effects of firms' prior CP experience and size as proxies for perceived legitimacy on owners' efforts at increasing giving and legitimacy. We find that state and CEO ownership are deterrents, while non‐SOE and institutional ownership enhances giving probability and amount. In addition, there is evidence that firm size and prior CP weaken the effects of institutional ownership on CP. This study provides a complete assessment of owner behaviour. Copyright © 2018 ASAC. Published by John Wiley & Sons, Ltd.     

Business model innovation: How the international retailers rebuild their core business logic in a new host country

Although research into the business model has received increasing attention, few studies have so far been conducted on business model innovation in an international context. The purpose of the study is to identify different patterns of business model innovation which enables international retailers to rebuild their core business logic in new host countries. On the basis of comparing and contrasting the business model changes of 15 international retailers from various home countries to one single host country (China), our study provides an in-depth understanding of business model innovation in the context of international business. By looking at the firms’ capabilities in rebuilding their core logic in the setting of a host country, we reveal six routes of retail business model innovation. Utilizing the lens of organizational learning theory and internationalization, we identify three patterns of resource deployment by international companies in the process of developing business model innovations. Our study, therefore, provides insights and guidance for multinational companies in general, international retailers in particular, as for how to successfully adapt their business model from home country to host country.     

一种基于TDOA的多天线联合测角算法

针对分布式多天线系统中传统测角方法存在测量精度偏低、宽带信号不适用等问题，提出了一种基于时延差（Time Difference of Arrival,TDOA）测量的多天线二维测角算法。该算法基于最小二乘原理，综合利用多基线测量结果进行迭代计算，有效提高了估计精度，且无需解模糊。推导了算法的克拉美罗界(Cramér-Rao Lower Bound，CRLB)与均方根误差表达式，讨论了算法的测角性能。当天线数为7、天线间距100 m、时延估计精度优于10 μs时，测角精度接近CRLB，方位角精度优于3°，俯仰角精度优于4°。算法复杂度适中，能够应用到多天线无源侦察、空间目标跟踪等应用中。