定时器的PLC程序设计

本文旨在实现接通延时定时器、断开延时定时器、多谐震荡器的时序图及PLC程序设计。     

The Rocky Road to Legacy: Lessons from the 2010 FIFA World Cup South Africa Stadium Program

This article describes how the management and organization of the South African 2010 FIFA World Cup stadium program shaped the current legacy of an oversupply of overdesigned and underutilized stadiums. The article identifies seven key factors that explain the differences between expected benefits and the actual legacy. Identification of these factors contributes to the increasing academic interest in explaining the poor legacy outcomes of mega‐events. In conclusion, we recommend that future host country governments defragment their stadium programs by establishing a World Cup Delivery Authority (WCDA), with responsibility for the leadership and coordination of the stadium program.     

欧盟海关同盟战略及其执行评析

摘要：海关同盟是欧盟的三大支柱之一，也是欧盟单一市场的基石。因此，欧盟一直通过其海关同盟战略及其各类实施工具来强化有效、高效、统一、协调的海关联盟。在三十年的海关同盟演进过程中，欧盟海关同盟战略都是承接并贡献于欧盟总体经济规划目标。在其三项海关同盟战略之间以及海关同盟战略与海关行动计划之间存在着延续与发展的关系。为了实现欧盟海关战略目标，欧盟采取了软硬结合的开放协调机制以实施其战略。     

Cropland expansion and grassland loss in the eastern Dakotas: New insights from a farm-level survey

The western Corn Belt region of the United States has become a hotspot for agricultural extensification and consequent land use and land cover changes. The goals of this research were to characterize geographic patterns of grassland loss resulting from cropland expansion in the eastern Dakotas, and to understand how these changes were associated with characteristics of individual farms and farm operators. We collected data on grassland conversion and other land use decisions through a mail survey of farm operators in North and South Dakota. Overall, 40% of respondents converted at least some grassland to cropland between 2004 and 2014, and the total acreage of converted grassland was equivalent to 5.1% of the surveyed farm acreage. Although most converted grassland acres (3.2% of farm acreage) were from land enrolled in the conservation reserve program (CRP), there were also substantial amounts of native grassland conversion (1.0%) and tame grassland conversion (0.9%). The total acreage of grassland conversion was more than four times larger than the acreage enrolled in CRP and other conservation programs. Different types of grassland conversion (e.g., native grassland versus CRP) were concentrated in different parts of the study region, and were spatially disjunct from the areas of highest conservation program enrollment. Larger farms were more likely than smaller farms to expand their cropland acreage and accounted for a disproportionate share of grassland conversion. Younger farm operators, higher levels of farm income, higher proportions of rented croplands, and marginal yields were also associated with cropland expansion and grassland conversion. Although CRP and other land retirement programs will remain important policy mechanisms for conservation in this region, they are not sufficient to maintain current levels of grassland cover and do not provide protection for native grasslands. Alternative conservation strategies and new agricultural policies are thus critically needed to maintain the ecosystem services provided by grasslands.     

Wheat variety yield data: Do commercial and public performance tests provide the same information?

Wheat yields from reported performance test results are of economic importance to wheat producers, since their profits depend on selecting the optimal variety for their location. However, our data shows differences in absolute and relative wheat yields between commercial and public wheat breeding program's performance test data in Kansas. Newly available data are used to test if the difference in yields arose from potential selectivity bias, and to determine the contribution of private and public wheat breeding programs to varietal yield improvement during 2007–2012. Both Heckman selection models and multiple regression showed no statistical evidence of the potential presence of selectivity bias rather, managerial practices, agronomic conditions, field location, and inherent genetic traits of the seed variety were identify as the source of yield differences.     

营改增背景下企业办税人员素质现状及提升路径

当前不断推进的营改增对企业税务管理工作提出了更高要求,对企业办税人员素质形成了新的考量。本文分析了营改增背景下税企双方对企业办税人员的素质要求,结合地方企业办税人员的素质现状,探究其影响因素。提出应严格企业办税人员准入制度,建立配套的职称晋升和有效的激励机制,为办税人员营造良好的职业发展空间,促进其综合素质的全面提升,为地方经济发展助力。     

Drivers of airline loyalty: Evidence from the business travelers in China

This paper examines the key factors that determine business traveler loyalty toward full-service airlines in China. Based on literature review and panel interview, ten airline attributes under three categories were derived: (a) operational factors: safety, punctuality, and aircraft; (b) competitive factors: frequency of flights, schedule, frequent flyer program, ticket price, and reputation; and (c) attractive factors: in flight food & drinks and in flight staff service. We surveyed 2000 Chinese business travelers on domestic flights, obtaining 462 usable questionnaires. Hierarchical regression analysis reveals that reputation, in-flight service, frequent flyer program, and aircraft have the greatest influence in driving airline loyalty.     

基于Excel的道路工程计算技术

围绕数据组织、数据的联动检索技术、Excel高级函数、Excel自定义函数、Excel VBA程序的开发过程,系统地建立了基于Excel的道路工程计算的框架模板。     

集装箱船初稳性高度优化模型的建立

为解决目前集装箱配积载中尚需结合人工经验来进行箱位选配的问题,通过研究集装箱船配积载前重心距基线高,运用集装箱船初稳性高度计算原理,结合集装箱船的结构特点,建立集装箱船初稳性高度优化模型。运用交互式的线性和通用优化求解器编写程序,其研究成果将为实现集装箱船自动化配积载目标提供理论基础。