德邦规模养种系统发展对策的关键变量关联反馈环分析

反馈环结构是复杂系统发生动态变化的核心结构，反馈环结构分析是复杂系统具体管理对策确定的关键。如何对反馈环结构进行流程化分析，实现有效的反馈环开发管理是待深入研究的重要问题。针对以上问题，提出了关键变量关联反馈环四步分析法：首先，利用系统动力学新的入树建模法，构建系统的流率基本入树模型；接着，根据系统发展目标，确定研究的关键变量；然后，用枝向量行列式算法计算出系统全部反馈环，构建关键变量关联反馈环结构流图，确定关联反馈环结构流图主导反馈环；最后，依据关键变量主导反馈环分析，确定管理对策。以德邦规模养种系统发展为例，建立了刻画此复杂系统的含六棵入树的流率基本入树模型。根据系统发展的3大目标，确定养殖利润、年种植有机肥施用量、户猪粪年产沼液量3个关键变量。在构建3个关键变量关联反馈环结构流图基础上，根据德邦规模养种系统发展实践，结合德邦养殖业、沼液资源开发、户用沼气池建设的历史数据，确定3个关联反馈环结构流图的主导反馈环。最后，根据主导反馈环分析，确定了系统发展的3条管理对策。德邦规模养种系统实施管理对策的实践，验证了3条管理对策的有效性，验证了此方法在确定复杂系统管理对策中的可行性。关键变量关联反馈环四步分析法，为反馈环结构分析提供了一种规范性的方法，为复杂系统发展管理对策的制定提供一个可操作的流程。     

The Interaction Effects of Frequency and Specificity of Feedback on Work Performance

ABSTRACT

This study investigated the interaction effect between specificity (specific vs. global) and frequency of feedback (frequent vs. infrequent) on the quality of work performance. Eighty participants were recruited and randomly assigned to one of the four groups: specific and frequent feedback, global and frequent feedback, specific and infrequent feedback, and global and infrequent feedback. A 2 × 2 factorial design was adopted. Participants were asked to work on a simulated order-fulfilling task and attended 24 sessions. The dependent variable was the error rate of the completed tasks. The results showed that more frequent feedback was more effective and specific feedback was more effective than global feedback in improving the quality of performance. Furthermore, an interactive effect between feedback frequency and specificity was found. Specific feedback was more effective than global feedback when the feedback was infrequent, but global feedback was comparable to specific feedback when it was frequent.     

双寡头市场中品牌广告竞争和大类广告合作策略研究

利用微分对策理论研究了一强一弱双寡头垄断市场中的品牌广告竞争和大类广告合作策略,提出了一个Stackelberg博弈模型,采用汉密尔顿-雅可比-贝尔曼方程求得了模型的均衡品牌广告、大类广告和价值函数,给出了市场份额计算公式。研究发现:与非合作策略相比,大类广告合作策略下,无论强者还是弱者,他们的销售量都增加了,同时两个企业的品牌广告投入也增加了;通过大类广告合作策略,无论强者(领导者)还是弱者(追随者),他们的利润都得到了提高;强者、弱者和行业的大类广告投入分别高于非合作下强者、弱者和行业的大类广告投入。     

The Structural Break in the Equity Premium

This article uses Bayesian marginal likelihood analysis to compare univariate models of the stock return behavior and test for structural breaks in the equity premium. The analysis favors a model that relates the equity premium to Markov-switching changes in the level of market volatility and accommodates volatility feedback. For this model, there is evidence of a one-time structural break in the equity premium in the 1940s, with no evidence of additional breaks in the postwar period. The break in the 1940s corresponds to a permanent reduction in the general level of stock market volatility. Meanwhile, there appears to be no change in the underlying risk preferences relating the equity premium to market volatility. The estimated unconditional equity premium drops from an annualized 12% before to the break to 9% after the break.     

现金配售制度下新股申购投资者的真实首日收益研究

以申购资金的真实首日收益(考虑中签率)为研究对象,分析其合理性及影响因素,并以1998～2007年现金配售发行的A股IPO公司为样本进行实证检验.研究发现,新股申购投资者并未获得高额的真实首日超额收益,一级市场过度的噪声申购需求导致收益降低,二级市场噪声需求引起的价格偏离导致收益提高;同时,较高的发行市盈率和较大的公司规模可抑制噪声申购需求而提高收益.     

Examining the Effects of Feedback Accuracy and Timing on Skill Acquisition

ABSTRACT

Feedback involves providing information about past performance and indicating how to improve future performance. Although the literature contains numerous examples of feedback as an effective method for improving performance across a range of organizational settings, much remains unknown about the specifics of how feedback acts to change behavior. This study evaluated the combined effects of feedback accuracy (100%, 80%, 20%) and timing (feedback following each trial or after a block of 25 trials) on skill acquisition in undergraduate students when presented with a computerized match-to-sample task that required participants to learn the names of shapes. Results reveal that feedback accuracy had a significantly greater effect on performance than the timing of the feedback.     

《模拟电子技术》课程教学中的共性问题

文章归纳了《模拟电子技术》课程教学中存在的几个共性问题,并通过对共性问题的阐述和分析,使学生在学习《模拟电子技术》时能更迅速、更轻松的掌握各部分内容,达到触类旁通的效果。     

政府机关窗口工作人员的心态调查

窗口工作人员的心态和行为直接影响了政府的服务效率和公众形象。文章采用自编调查问卷的方式,从工作价值感、内部管理、压力管理这三个方面对北京某政府机关单位220名员工进行调查。结果表明:多数员工存在自我认知偏差,感觉受到的待遇不公平,不能以积极心态从事工作;同时管理者的正反馈偏少,也很大程度上影响着员工的心态。     

论矿山动力现象研究的哲学精神

自然辩证法的若干思想在科学研究中起着重要作用。正确地处理好科学研究中的一些哲学问题,用辨证的思想方法去解决科学难题,对科学研究大有裨益。作者在矿山动力现象的研究中巧妙地运用了辨证的思想,取得了很好的效果。     

人的自我调节机制述评

当前人类的自我调节机制研究主要集中在目标的选择、认知和调节上。自我调节的基本机制包括5个相互联系的重复阶段一目标选择;二目标认识;三方向维持;四方向的改变或修正;五目标终止。另外,自我调节机制的失败有着许多影响因素。