皮带运输机皮带跑偏成因及解决办法

为保障皮带运输机的安全运作,避免跑偏状况出现,本文针对皮带运输机的结构和工作原理进行分析,详细研究了可能引起皮带跑偏的一些原因,并针对原因提出了相应解决办法.     

Is it still economic to build a new coal-fired power plant in the U.S.? A real option analysis

In the U.S., virtually no new coal-fired power plants have been built in recent years. Both industry experts and academics seem to believe that no rational firm will build a new coal-fired plant. Will such a trend continue in the future? To provide insights into this question, we investigate the optimal decision of an electricity company with an irreversible and deferrable opportunity to build either a new coal-fired or natural gas-fired power plant as its new base-load resource. According to our real option analysis, the optimal decision depends on the location. In the case of the eastern U.S., it is optimal to choose a natural gas plant if a firm is given a choice among a new natural gas plant, a new coal plant and deferring the investment. However, contrary to the common sentiment in the industry and academia, building a new coal plant in the western U.S. is still more economical than building a new natural gas plant in the absence of emission pricing. Furthermore, introducing carbon pricing to western U.S. states, as California did, can substantially increase the probability that a firm will optimally choose a natural gas plant over a coal plant.     

Capital asset pricing model in Portugal: Evidence from fractal regressions

We examine risk profiles of the Portuguese stock market index component stocks using a novel approach to the classical capital asset pricing model (CAPM). Specifically, we estimate the CAPM via fractal regressions that allow studying the marginal effects at selected scales. In this way, we can reveal whether the risk is perceived differently by market participants with different investment horizons. Apart from the analysis itself, we provide new statistical insights into the issue of separating and comparing the scale-specific effects with statistical validity. We find several stocks deviating from an expected risk perception homogeneity across investment horizons. This is true for both analysed periods, i.e. before and after the global financial crisis. There are also several stocks that changed their relationship to the market portfolio in between, which has strong implications for possible portfolio construction. The proposed methodology is not limited to financial topics but can be used in any discipline where the scale-specific marginal effects might be of interest.     

The Structure of Problem Structuring Conversations: A Boundary Games Approach

One of the questions associated with facilitated problem structuring is how the micro level of actors’ multimodal communications, contributes to the emergence of a macro level, framing the possibilities for action in a workshop. This paper shows a way to study this macro level, building the visualization of the conversations’ structure starting from a boundary games theory micro analysis of the interactions. Our empirical evidence comes from following a group of academic consultants working to define a value proposition for their activity. We focus on analyzing two out of nine workshops that were felt diametrically opposite in terms of facilitation and achievements. Moving from the micro towards an upward level, three configurations building the structure are identified—shifting, branching and converging. The work carried out allows us to: (1) visualize the structure of conversations in a problem structuring context, (2) highlight the role of multimodal communications in building the conversations and (3) construct an interpretation bridging the micro and macro readings of a workshop. This knowledge is useful for facilitators guiding the dynamic of a workshop and for researchers looking forward to understanding how micro level interactions build higher levels of the social phenomenon of intervention.     

Public debt and economic growth in Spain, 1851–2013

In this paper we investigate the long-run relationship between public debt and economic growth in the Spanish economy for the period 1851–2013. We develop a cliometric analysis of the debt–growth nexus using novel time series methods. We find some support for a negative relationship between both variables, but no clear evidence of a debt threshold. The estimated long-run elasticity in a one-break model shows a tendency to decrease over time from a nonsignificant 0.011 to a ?0.070, indicating that a 10 percentage increase in the public debt-to-GDP ratio is associated with 0.70 percentage points lower real economic growth. Indeed, we find for the first subsample (1851–1939) either “decoupling” or “saturation,” while in the second subsample (1940–2000) the long-run elasticity coefficient becomes negative and significant. When we extend our analysis up to 2013, we find a break in 1971 coinciding with the twilight of Franco’s dictatorship and the Spanish transition to democracy.     

股价信息含量与投资-股价敏感性——基于融资融券的准自然实验

本文利用2006-2015年间的数据研究了融资融券对投资-股价敏感性的影响。利用融资融券作为股价信息含量的一个外生冲击变量,本文研究发现,我国A股市场确实存在反馈效应,融资融券政策的实施增强了标的公司投资-股价敏感性,这个结论在采用倾向得分模型(PSM)配对后依然成立,说明融资融券使股价融入了更多有利于管理层投资决策的信息。其次,融资融券对投资-股价敏感性的影响在机构投资者比例高、流动性高、处于新兴行业的这类管理层反馈效应更强的股票组中更显著。参照以往研究考虑了融资约束对反馈效应的调节作用,同样发现融资融券对投资-股价敏感性的影响在国有企业和规模较大的企业组中更显著。最后,融资融券交易规模越大,投资对股价的敏感性越强。     

Structural comparisons of networks and model-based detection of small-worldness

In this paper, we consider the problem of assessing the “level of small-worldness” of a graph and of detecting small-worldness features in real networks. After discussing the limitations of classical approaches, based on the computation of network indicators, we propose a new procedure, which involves the comparison of network structures at different “observation scales”. This allows small-world features to be caught, even if “hidden” deeply into the network structure. Applications of the procedure to both simulated and real data show the effectiveness of the proposal, also in distinguishing between different small-world models and in detecting emerging small-worldness in dynamical networks.     

Consumer Law and Policy in Ghana

This paper presents a picture of the landscape of consumer law and policy in Ghana and reviews the scope of protection of consumer interests with specific regard to product safety and liability, consumer sales, and telecommunication services. It assesses the legislative and policy framework on consumer contracts, product safety, and unfair commercial practices; discusses the role of national agencies in enforcing safety standards; and highlights some critical consumer issues in telecommunications service delivery. The paper examines the regulatory framework on other consumer issues such as advertising, labelling, and marketing of consumer products; terms and conditions of consumer contracts; and after sales services including the enforcement of guarantees, warranties, refund, and return policies. The paper also discusses the extent of external influence on the development of consumer law and policy in Ghana and reviews the level of interaction with other legal systems and supranational bodies in the three focal areas. The contribution also explores areas of Ghana’s consumer protection framework which could benefit from guidance from the EU transnational model on consumer protection and makes recommendations for the enhancement of the emerging legislative and policy regime on consumer protection in Ghana.     

Impact of Online Customer Reviews on Sales Outcomes: An Empirical Study Based on Prospect Theory

This study examines the influence of the valence of online customer reviews on sales outcomes based on prospect theory. Numerous studies have revealed the importance of customer reviews in online marketing. However, only few studies have explored the impact of online customer reviews on sales outcomes in the dynamic process. Prior studies in behavioral economics literature have indicated that people differently value gains and losses and that losses have more emotional impact than an equivalent amount of gains. This study verifies whether prospect theory applies to the relation between online customer reviews and sales outcomes. Relevant data were collected from Amazon.co.jp, and three statistical models were employed to investigate the relation between the two factors. Major findings confirm that negative customer reviews considerably impact online sales than positive reviews. Furthermore, the findings indicate that the marginal effects of positive and negative reviews decrease with the increase in their volume. The results of this study will enable marketers to compare the relative sales effects of different types of customer reviews and improve the effectiveness of customer service management.