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161.
162.
提出一种基于双幂次组合函数趋近律的新型滑模控制方案。与现有的快速幂次或双幂次趋近律相比,具有更快的收敛速度,同时还保持了全局固定时间收敛特性,收敛时间上界与滑模初值无关。当系统存在有界扰动时,能够使滑模变量在有限时间内收敛到稳态误差界内,同时其稳态误差要小于现有方法的。仿真实验验证了该方法的有效性及理论分析的正确性。 相似文献
163.
China’s defence expenditure has been growing rapidly along with GDP growth during the past two decades. Meanwhile, the income gap has continued to increase. There are conflicting views regarding whether the defence expenditure is capable of reducing income inequality. Therefore, this paper investigates the existence of any spillover effect of defence expenditure on income inequality, with a special focus on the regional differences among 31 provinces and 7 military regions in China. We extend panel cointegration and the impulse response function by using panel data during the period of 1997–2012. The empirical results show that the defence expenditure has an impact on income inequality, and the effect varies over different regions in China. The defence expenditure has a spillover effect on income inequality in the full sample panel and the southeastern panel. An increase in the defence expenditure does not crowd out social welfare spending due to the high level of economic development and government expenditure. On the contrary, in the northern panel, the effect is opposite because of the unbalanced economic development levels within the panel. Beijing as the capital of China, benefits more from the expansion of defence expenditure thus widening the income gap. In addition, the impulse response analyses further confirm a stronger effect of the defence expenditure on income inequality in the northern and the southeastern panels over a short period. 相似文献
164.
为提高强背景噪声下频谱分析的特征提取能力,突出所关心的特征谱线,在非线性变换方法的基础上,提出了广义非线性变换方法。对比分析结果表明:广义非线性变换方法将固定的放大阈值改为可变值,提高了该方法实际应用的灵活性和适用性,易于获得最佳的特征谱线增强效果。 相似文献
165.
166.
大学生思想政治教育中的“沉默螺旋”现象 总被引:1,自引:0,他引:1
"沉默的螺旋"理论是20世纪70年代德国社会学家诺尔诺依曼基于历史和传播的角度提出的关于舆论形成的理论假设,是现今学界研究受众反应的经典理论之一。本文就沉默螺旋理论在当代大学生思政传播中的存在性进行了论证,并分析了其对大学生思想政治教育可能产生的影响,结合实际,探讨了降低其负面影响的对策。 相似文献
167.
We consider a three‐layer supply chain with a manufacturer, a reseller, and a sales agent. The demand is stochastically determined by the random market condition and the sales agent's private effort level. Although the manufacturer is uninformed about the market condition, the reseller and the sales agent conduct demand forecasting and generate private demand signals. Under this framework with two levels of adverse selection intertwined with moral hazard, we study the impact of the reseller's and the sales agent's forecasting accuracy on the profitability of each member. We show that the manufacturer's profitability is convex on the reseller's forecasting accuracy. From the manufacturer's perspective, typically improving the reseller's accuracy is detrimental when the accuracy is low but is beneficial when it is high. We identify the concrete interrelation among the manufacturer‐optimal reseller's accuracy, the volatility of the market condition, and the sales agent's accuracy. Finally, the manufacturer's interest may be aligned with the reseller's when only the reseller can choose her accuracy; this alignment is never possible when both downstream players have the discretion to choose their accuracy. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 207–222, 2014 相似文献
168.
This article compares the profitability of two pervasively adopted return policies—money‐back guarantee and hassle‐free policies. In our model, a seller sells to consumers with heterogeneous valuations and hassle costs. Products are subject to quality risk, and product misfit can only be observed post‐purchase. While the hassle‐free policy is cost advantageous from the seller's viewpoint, a money‐back guarantee allows the seller to fine‐tune the consumer hassle on returning the product. Thus, when the two return policies lead to the same consumer behaviors, the hassle‐free policy dominates. Conversely, a money‐back guarantee can be more profitable even if on average, high‐valuation consumers experience a lower hassle cost than the low‐valuation ones. The optimal hassle cost can be higher when product quality gets improved; thus, it is not necessarily a perfect proxy or signal of the seller's quality. We further allow the seller to adopt a mixture of these policies, and identify the concrete operating regimes within which these return policies are optimal among more flexible policies. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 403–417, 2014 相似文献
169.
We study a supply chain in which an original equipment manufacturer (OEM) and a contract manufacturer (CM) compete in the finished goods market. The OEM can decide whether to outsource the intermediate good, a critical component for producing the finished good, from the CM or make in‐house production. Technology transition improves the CM's production efficiency, and it can take two different forms: a direct technology transfer from the OEM to the CM or technology spillovers through outsourcing from the OEM to the CM. We document the possibility of strategic outsourcing, that is, the CM supplies the intermediate good to the OEM when she is less efficient than the OEM's in‐house production. We find that technology spillovers can strengthen the incentive for strategic outsourcing. Furthermore, compared with direct technology transfers, outsourcing coupled with technology spillovers may generate more technology transition. Outsourcing is a particularly appropriate channel for implicit collusion when the OEM is not very efficient with the production of the intermediate good. Our results suggest that ex post competition on the finished goods can create room for ex ante collaboration and provide some implications on the OEM's outsourcing strategies when facing a competitive CM.© 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 501–514, 2014 相似文献
170.
针对地球遮挡、地影、太阳光干扰、月光干扰、空间目标相对观测平台的角速度等约束对空间目标可见性的影响问题,基于已编目空间目标双行轨道根数,研究以太阳同步晨昏圆轨道作为观测平台轨道,采用改进多变异位自适应遗传算法对单星观测平台轨道倾角进行优化设计。仿真结果表明,改进的多变异位自适应遗传算法有效地解决了多变异位自适应遗传算法不能保证收敛到所有种群中最优个体的问题,且随机抽取10%左右的目标样本可以达到与采用所有目标相当的性能,计算效率提高约1个量级。 相似文献