一种井口压装防喷装置的设计

一种井口压装防喷装置,在井口压裂过程中,用于投放油管堵塞器以堵住油管,防止井喷。其结构包括上下旋塞阀和升高短节。当钻井产生井喷时,保证旋塞阀的上下两端压力平衡,使旋塞阀可以轻松打开,升高短节内的油管堵塞器即能自动下降密封。     

TS模糊模型在个股股价预测中的应用研究

个股价格短期内的变化量一般可通过股票技术指标间接反映出来,且这些指标间有着一定的相关性;另外,股票价格模型具有Takagi-Sugeno(TS)模糊模型所研究问题的非线性、时变性特点,基于此,本研究将TS模糊模型与分析出的股票常用技术指标相结合进行股价预测。结果显示预测出的价格与股票实际价格近似一致,精度高,因此研究具有一定的实用价值。     

Shorting costs and profitability of long–short strategies

We examine how the profitability of long–short arbitrage strategies based on anomalies is affected after adjustment for two shorting costs: implicit cost due to unavailability of stocks in the short-leg to sell short and loan fees actually paid to stock lenders. The combined shorting cost amounts to almost 40 percent of long–short gross returns over the sample period from January 2006 to December 2017. After adjustment for these shorting costs, long–short arbitrage profits are thus reduced by almost 40 percent. Even after adjustment for risk, the proportion of shorting costs is also substantial. If other trade-related transaction costs are considered, long–short arbitrage profits would be reduced further. Our results provide explicit evidence that casts doubt on the profitability of long-short arbitrage strategies based on anomalies.     

Short Selling Pressure,Stock Price Behavior,and Management Forecast Precision: Evidence from a Natural Experiment

Using a natural experiment (Regulation SHO), we show that short selling pressure and consequent stock price behavior have a causal effect on managers’ voluntary disclosure choices. Specifically, we find that managers respond to a positive exogenous shock to short selling pressure and price sensitivity to bad news by reducing the precision of bad news forecasts. This finding on management forecasts appears to be generalizable to other corporate disclosures. In particular, we find that, in response to increased short selling pressure, managers also reduce the readability (or increase the fuzziness) of bad news annual reports. Overall, our results suggest that maintaining the current level of stock prices is an important consideration in managers’ strategic disclosure decisions.     

浅析远程监控的数据传输

文章论述了远程监控系统数据传输技术的重要性以及常用的几种实现方式,并对其优缺点进行了比较和分析。文中分析了利用全球移动通信系统(GSM)进行数据传输的优越性,并介绍了GSM传输的3种方式的特点,各自的实现方式,最后展望了远程监控数据传输的发展前景。     

Investment Horizon and Repo in the Over‐the‐Counter Market

This paper presents a three‐period model featuring a short‐term investor in the over‐the‐counter bond market. A short‐term investor stores cash because of a need to pay cash at some future date. If a short‐term investor buys bonds, then a deadline for retrieving cash lowers the resale price of bonds for the investor through bilateral bargaining in the bond market. Ex‐ante, this hold‐up problem explains the use of a repo by a short‐term investor, the existence of a haircut, and the vulnerability of a repo market to counterparty risk. This result holds without any uncertainty about bond returns or asymmetric information.