ANALYSIS OF TWO-PHASE FLOW PRESSURE BUILDUP DATA FROM A WELL IN AN INFINITE MULTIWELL RESERVOIR

NOMENCLATURE A1———drainage area of the tested well ( Well 1) At———total reservoir drainage area B———two-phase formation volume factor C———wellbore storage coefficient Cf———rock compressibility fator Co———oil compressibility fator Cw———water compressibility fator Ct———compressibility fator K———reservoir permeability m———slope of a semilog straight line m1———slope defined by Eq.(12) p-———average reservoir pressure-pD———di mensionless average drainag…     

Goodwill write-off and financial market behaviour: An analysis of possible relationships

The aim of this contribution is to verify whether there exists a reaction of financial markets to the new accounting method for goodwill introduced by SFAS 142 and IAS 36. Our research hypothesis is that financial markets should have no significant reaction to the goodwill write-off following the impairment test, since the latter's outcome represents an economic estimate without financial significance. The hypothesis was checked by the analysis of the companies added to the Standard & Poor's Europe 350 index over a three-year period, taking note of goodwill write-off announcements and relating them with the stock market prices and their volatility. The results demonstrate a correlation between the goodwill write-off and the behaviour of financial markets, while the same connection cannot be evinced for prices volatility. Also, what comes out from our analysis is that markets need a relatively long period, over one semester, before absorbing in full the effects resulting from the write-off announcement.     

Evaluating asset pricing models using the second Hansen-Jagannathan distance

We develop a specification test and a sequence of model selection procedures for non-nested, overlapping, and nested models based on the second Hansen-Jagannathan distance, which requires a good asset pricing model to not only have small pricing errors but also be arbitrage free. Our methods have reasonably good finite sample performances and are more powerful than existing ones in detecting misspecified models with small pricing errors but are not arbitrage-free and in differentiating models that have similar pricing errors of a given set of test assets. Using the Fama and French size and book-to-market portfolios, we reach dramatically different conclusions on model performances based on our approach and existing methods.     

The Diversification Effects of Initial Public Offerings

Abstract:  A firm's stock becomes publicly tradable through an initial public offering (IPO). This study suggests a portfolio diversification perspective to explore IPOs. We examine whether investors can gain diversification benefits by adding an IPO portfolio to a set of benchmark portfolios sorted by firm size and book-to-market ratio. Using US IPOs from 1980-2002, we find that adding a value-weighted IPO portfolio does lead to a statistically and economically significant enlargement of the investment opportunity set for investors relative to investing solely in a set of benchmark portfolios. Specifically, the Sharpe ratio of the tangency portfolio increases by 5.50% on average after including IPO stocks. Furthermore, IPOs associated with prestigious lead underwriters are the main source of this augmentation of the mean-variance investment opportunity set. Finally, our study implies that issuing IPO exchange traded funds or similar products can provide diversification gains to investors.     

三轴应力状态下砂砾料浸水变形特性试验研究

利用VJ非饱和三轴仪对砂砾石料进行了各向等压和剪切状态下浸水变形特性试验研究,并对不同应力状态下浸水变形过程中体应变和偏应变增量进行统计分析。假定体积应变增量在试样各向同性和等压固结条件下可分解成两部分,一部分是由于围压σ3引起的,另一部分是由于偏应力引起的;偏应变仅由偏应力引起的。在此假定的基础上建议了一个浸水体应变增量和偏应变增量与应力水平和围压之间的经验表达式以及相应的参数整理方法。     

稠油注汽系统能耗测试方法与效果评价

为降低稠油开采成本和提高经济效益,对稠油注汽系统采取了一些节能技术改进措施,并应用了一些节能产品,以提高注汽系统热效率。为了评价改造后稠油注汽系统的热效率及使用配套节能产品的效果,给出了稠油注汽系统技改能耗测试要求、测试程序与方法、测试结果评价指标及评价方法;并对技改前后稠油注汽系统能耗进行了综合评价,说明所采取的技改措施是有效的。     

巴歇尔槽测验精度研究

巴歇尔槽在水文实验、水量平衡计算、水资源调查得到了广泛的应用,但是,理论公式和实用公式之间精度差别究竟多大,在多年的径流观测中一直没有验证,本文就此展开初步的探讨。     

U形渠道弧底平板闸门水力性能研究

为解决灌区U形渠道缺少流量测控设施的问题,根据U形渠道断面尺寸设计一种弧底平板闸门,由闸板和闸墩组成。设计1∶1、2∶3、1∶2共3种收缩比的闸门,采用原型试验和数值模拟相结合的方法研究弧底平板闸门的水力性能。结果表明：不同收缩比的闸门水面线变化规律基本一致,但水头损失随着收缩比的减小而增大。优选收缩比为1∶1的弧底平板闸门作为U形渠道测控设施,建立闸孔出流测流公式。通过Flow-3D软件得到渠道弧底平板闸门上、下游断面水流流速和佛汝德数沿程分布规律,不同开度下的闸前流速分布规律一致,最大流速位于中垂线处自由水面中心以下区域。闸门上游佛汝德数小于0.5,符合测流条件,下游佛汝德数最大值的区域集中于闸后贴近渠壁两侧的自由水面。研究结果可作为U形渠道测控设施的设计和优化提供依据。     

数字技术能否助力科技创新?——基于国家级大数据综合试验区的分析

以大数据引领推动科技创新是实施大数据战略行动的关键一环。基于2007—2019年的中国城市面板数据,以国家级大数据综合试验区为准自然实验,从理论和实证两方面,通过多期双重差分模型,系统分析数字技术对科技创新的影响。为证明结果的可靠性,进行一系列稳健性检验。研究结果显示,提升数字技术水平会显著促进科技创新水平,且数字技术的作用强度具有区域异质性,呈现南部地区>北部地区、高行政等级城市>一般地市的情况。基于以上结果,提出对策建议：进一步推动大数据试验区建设,优化创新制度环境,完善人才流动机制,充分发挥数字技术对科技创新的促进作用。     

某工程混凝土强度不足的原因和事故处理方法

某商场为4层框架结构,在施工过程中经检测部分区域梁、板、柱混凝土强度偏低,根据混凝土回弹及取芯的强度试验报告、水泥安定性和缓凝减水剂试验报告,分析得出混凝土强度不足的原因为缓凝减水剂质量不合格,并结合工程实际,提出了加固处理方案。目前该工程加固已经完工并通过验收,2年来运行良好。