地下综合管廊混凝土爆灰检测及加固

针对某市钢筋混凝土地下综合管廊的现浇顶板、侧壁出现的混凝土爆灰质量缺陷,为确保管廊结构的安全使用,采用钻心法、超声波法、沸煮试验、爆灰物质的化学成分分析等检测方法,对爆灰现象进行了检测。结果显示,混凝土中存在的块状氧化钙与水熟化后体积增大1倍~2.5倍,使得混凝土在强度未达到设计抗拉强度前在块状氧化钙体积膨胀应力作用下被拉裂,导致了此类质量缺陷的发生。分析了质量缺陷对管廊结构的影响,并对管廊结构进行了加固设计及处理,满足了结构的正常安全使用要求。研究结果可为类似爆灰缺陷的设计及处理提供参考。     

Exploring sentiment-driven trading behaviour of different types of investors in the London office market

We investigates the sentiment-driven trading behaviour of the four types of investors in the London office market, i.e. UK institutional investors, UK private investors, UK listed real estate companies/Real Estate Investment Trust (REIT)s and overseas investors. In addition, we examine the relationship between investor sentiment and property performance. Related indices are calculated to examine the existence of herding behaviour of different investors. We find that UK private investors follow a contrarian strategy to UK institutional investors and listed real estate companies/REITs and enter/exit the market at different points of time. UK institutional investors tend to follow the sentiment of UK listed real estate companies/REITs and overseas investors with lags. There is no evidence that overseas investors rely upon the sentiment of UK specialised property investors in their decision-making. We find the sentiment of different investors is influenced differently by market fundamentals. Yield and rental growth rate have significant impact on trading activity of overseas investors, but not on other investors. The stock market return and securitised real estate return have significant impact on the trading activity of UK institutional investor and overseas investor, but have no significant influence on the trading behaviour of UK private investor and listed real estate company/REIT.     

The economics of markets and platforms

Advances in the study of both markets and platforms contribute to economics. Platforms are typically digital markets, although platforms can designate markets generally. So, the economics of markets and the economics of platforms are one and the same. Platforms show the critical role of intermediaries in endogenous price adjustment and market clearing. The platform model remedies problems with general equilibrium analysis by combining and extending the basic Walrasian and Marshalian market models. The analysis of platforms provides explanations for the bid–ask spread, including market power, search costs, matching costs, adverse selection, and moral hazard. The study of platforms demonstrates the importance of participation and coordination in the formation of markets. The discussion emphasizes that platforms have significant implications for the theory of the firm. The analysis further considers how platforms affect innovation and entrepreneurship.     

Noise traders,firm-specific uncertainty and technical trading effectiveness

This is the first study to document evidence of technical trading effectiveness at firm level in the Chinese A-share market by investigating the relationship between excess profits of technical trading rules and firm-specific characteristics. Our results reveal that firms with higher excess profits from technical trading have more noise traders and higher institutional ownership and that those firms tend to be growth firms with lower liquidity and higher firm-specific uncertainty. Further analysis shows that the profitability of technical trading rules is unsustainable and the excess profits of the highest technical trading profit quintile portfolio disappear in the following year.     

Farm size and productivity growth in the United States Corn Belt

In recent decades, agricultural production in the U.S. has continued to shift to large-scale operations, raising concerns about the economic viability of small and midsized farms. To understand whether economies of size provided an incentive for the consolidation of production, the study estimates the total factor productivity (TFP) of five size classes of grain-producing farms in the U.S. Heartland (Corn Belt) region. Using quinquennial Agricultural Census data from 1982 to 2012 the study also compares TFP growth rates across farm sizes to gain insight into whether observed productivity differences are likely to persist. The finding of a strong positive relationship between farm size and TFP suggests that consolidation of production has contributed to recent aggregate productivity growth in the crop sector. The study estimates the extent to which sectoral productivity growth can be attributed to structural change versus other factors including technological change. The study also explores some tradeoffs associated with policies that raise the productivity of small versus large farms.     

Co-movement in Stock Prices in Emerging Economies: The Case of the Caricom Region

The Grand Anse Declaration of 1989 recognised the need for financial integration within the emerging economies that comprise the CARICOM region, as a way of furthering the wider process of economic integration and, indeed, economic development in that region. Using co-movement as a measure of financial integration, this paper investigates the co-movement in stock prices among the Barbados, the Jamaica and the Trinidad and Tobago Stock Exchanges, the three major exchanges within the CARICOM region. It also examines how integrated these exchanges are with the New York Stock Exchange. The GARCH-Copula methodology and, to a lesser extent, estimated correlation coefficients, are used to attain this objective. There appears to be co-movement in stock prices and returns within the CARICOM stock markets and significant dependence structures between the returns of the three CARICOM stock markets. However, there is considerably less evidence of integration between the CARICOM markets and the New York Stock Exchange.     

The importance of consumer multihoming (joint purchases) for market performance: Mergers and entry in media markets

Consumer “multihoming” (watching two TV channels, or buying two news magazines) has surprisingly important effects on market equilibrium and performance in (two‐sided) media markets. We show this by introducing consumer multihoming and advertising finance into the classic circle model of product differentiation. When consumers multihome (attend more than one platform), media platforms can charge only incremental value prices to advertisers. Entry or merger leaves consumer prices unchanged under consumer multihoming, but leaves advertiser prices unchanged under single‐homing: Multihoming flips the side of the market on which platforms compete. In contrast to standard circle results, equilibrium product variety can be insufficient under multihoming.     

产业集聚、市场集中对区域创新能力的作用——基于京津冀、长三角两大经济圈制造业的比较

产业集聚和市场集中是影响区域创新能力的重要因素。本文考察了京津冀、长三角两大经济圈制造业产业集聚与市场集中对区域技术创新能力的作用。实证分析结果表明：两大经济圈制造业集聚与市场集中均在一定程度上促进了区域创新能力的提升，但由于两大区域体制机制条件、创新环境、产业组织形态等不同，制造业产业集聚影响区域技术创新的程度、特征与路径也存在一定差别。两大经济圈应采取差异化集群发展方式，加快推进制造业集群升级，特别是应抢抓第四次工业革命发展机遇，提升制造业智能化水平，提升区域创新能力水平。