Buyer Alliances as Countervailing Power in WIC Infant-Formula Auctions

State agencies in infant-formula procurement auctions receive lower bids when they are in buyer alliances than when they are unallied. The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) uses an auction to procure infant formula. Manufacturers bid on the right to be an agency’s sole supplier by offering a rebate on formula sold through WIC. Agencies frequently join together in buyer alliances. An empirical estimation shows that bids are lower to alliances and that lower prices result because alliances are heterogeneous. Results suggest that when heterogeneity is not controlled, bids decline with alliance size, which has policy implications because Congress recently limited alliance size.     

2013年国际煤炭市场分析及2014年展望

从煤炭供给、煤炭需求、煤炭进出口、煤炭价格等多个方面,全面介绍和分析了国际煤炭市场运行情况;并对2014年国际煤炭市场进行了预测与展望。     

中国区域金融发展差异的财政因素研究——基于财政压力与地方政府干预视角的分析

本文从各区域财政能力与金融能力变动的对比入手,证实了我国各区域均存在＂强金融,弱财政＂现象。用财政压力指标替换财政能力指标,详细论证了区域财政压力增长率与区域FIR增长率之间存在的反向变动关系。最终说明了区域财政压力差异性造成地方政府干预金融资源市场化配置的激励不同,并最终导致区域金融发展速度差别这样一个连锁反应的存在。     

春季石家庄市水体浮游植物群落结构调查与分析

为探索春季石家庄市水体浮游植物群落组成与结构特点,及其主要环境影响因素,对水体中浮游植物的种类组成、细胞密度、环境因子等指标进行了调查,分析了其物种优势度、多样性指数,并对各水体的浮游植物组成与环境因子进行了聚类分析和相关性分析。结果发现:在春季的石家庄市水体中,共检出浮游植物7门47属76种,以绿藻门种类最多,约占总数的39.47%,其次为硅藻和蓝藻,裸藻、金藻、黄藻和甲藻种类很少且仅在个别采样点位出现。水体中硅藻细胞密度最高,平均为1.0×10~7 cells/L,占丰度组成的61.84%,其次为绿藻和蓝藻。值得注意的是,岗南水库是所有水体中仅有的金藻丰富型水体,它的金藻细胞密度高达4.5×10~6 cells/L。物种优势度分析和多样性指数分析显示,石家庄市水体中以中度富营养型指示藻类为优势类群,基本处于中度污染水平;水体聚类分析表明,石家庄市水体的浮游植物组成受整体水环境因素影响不明显;而单环境因子数据及其与浮游植物的相关性分析表明,石家庄市水质酸化严重(pH值低于6.0),除科大牧星湖和岗南水库外,多数水体处于劣V类水平,主要超标物为pH值、总磷、总氮和COD,而这可能是导致蓝藻、绿藻等耐污性种类大量繁殖的主要因素。因此,对石家庄市水体中浮游植物群落组成与结构变化的生物学监测,是进行石家庄市地表水水质监测及生态保护的重要途径。     

基于改进粒子群算法的无人机航迹规划

针对当前基本粒子群算法无人机航迹规划在后期收敛速度比较慢、效率不高、易陷入局部最优等问题,提出一种改进粒子群算法。首先,在迭代前期和后期分段设置惯性权值的调整,实现粒子惯性和寻优行为的平衡;其次,设置一个定值与相邻2次适应度函数最优值比较策略,防止陷入局部最优;最后,引入遗传算法的交叉、变异机制,得出更优的结果。并通过仿真验证了改进粒子群算法在三维空间航迹规划的有效性和可行性。结果表明,与其他航迹规划算法相比,新算法具有路径长度更短、耗时更少、路径更平滑等优点,加快了收敛速度,提高了航迹规划效率和稳定性。因此,改进算法的航迹规划可得到满足约束关系的最优航迹,对实现自主飞行有重要的参考价值。     

Non‐Standard Time Wage Premiums and Employment Effects: Evidence from an Australian Natural Experiment

We examine the effect of increasing Sunday wage premiums on retail industry employment in Australia, exploiting a quasi‐experimental policy change across two neighbouring states. Using both aggregate and individual‐level data, we adopt a difference‐in‐difference regression framework to estimate the causal impact of the policy change on employment outcomes. We find no evidence of changes in the total number of employees, and no effect on hours per employee in the years following the policy implementation. However, there appeared to be a decline in hours per employee in the announcement year of the policy change. Overall, it appears that in an industry dominated by part‐time and casual employment, any adjustment to the new Sunday wage rates occurred principally through flexibility in hours, rather than in the number of employees.     

The impact of earnings pressure on exploratory innovation

While earnings expectation has been shown to determine a firm’s investment decisions, the knowledge about how such expectation influences a firm’s investment horizon for innovation is still blurred. This study therefore addresses this research issue by examining the relationship between earnings pressure and exploratory innovation while investigating the moderating effects of cross‐rival effect and resource availability. By examining high‐tech industrial firms in S&P 1500 from 2000 to 2012, the results indicate that stock analysts, as information intermediaries between innovation firms and the capital market, impose pressure through earnings forecasts on firms’ exploratory innovation. Our findings also reveal that the earnings pressure‐exploratory innovation relationship can be mitigated when its competitors encounter a higher level of earnings pressure. However, a firm’s financial slack shows less significant association to moderate the earnings pressure‐exploratory innovation relationship. Possible explanations for the results in regard to their theoretical and practical implications are discussed in this study.     

A design-led conceptual framework for developing school integrated STEM programs: the Australian context

International Journal of Technology and Design Education - Integrated Science, Technology, Engineering, and Mathematics (STEM) education is recognised as the latest development stage on the pathway...     

基于宏观线收缩率的复合材料固化变形仿真预测

纤维增强树脂基复合材料在固化过程中受材料体系(如树脂类型与体积含量、纤维类型等)和固化制度(如固化设备、固化压力、固化升降温速率、固化模具类型等)的影响,会在宏观层面产生固化变形,影响复合材料制件的形面精度。提出基于宏观线收缩率的固化变形仿真预测方法,在材料体系和固化制度一定的条件下,对各理化变量进行常数化处理,归结为X、Y、Z三个方向长度变化量与固化前长度的比值。建立有限元仿真模型,预测对称铺层和非对称铺层C型试验件的固化变形结果,与实际扫描结果进行对比。结果表明：仿真预测结果最大相对误差为10.68%,平均相对误差为3.59%,预测精度能够满足工程实践的需要,极大降低了固化变形预测难度,能够对模具补偿形面设计、制件固化变形控制等起到切实的指导作用。