三线铁路荷载作用下箱梁桥荷载横向分布系数

文章运用有限元程序对三线铁路预应力混凝土连续箱梁桥进行了模拟,分析了三线铁路荷载作用下箱梁的受力特性及在各种荷载工况下荷载横向分布规律,给出了荷载横向系数的实用值。     

Motives in the Acquisitions of NASDAQ Targets during the Aftermath of the 1987 Crash

After the crash of 1987, the Nasdaq composite index stayed below the precrash level for nearly two years. Takeover activity surged in this after‐crash period. We compare the motives in the acquisitions of Nasdaq targets during the after‐crash period with those in the ten‐year period before the crash. We find that the announcement period return to acquirers and the proportion of acquirers with positive gains declines in the after‐crash period. For both the periods, agency is the motive for takeovers that have negative total gains (acquirer + target), but synergy and hubris are comotives for takeovers that have positive total gains. The proportion of takeovers in which the managers of acquirers act against the interest of the shareholders increases after the crash.     

“入世”对石家庄市优质农产品及加工业的影响程度分析

本文以第一手的资料详细阐述了在石家庄市农产品的现状,分析了我国加入WTO将对石家庄市农产品产生的影响（机遇与挑战）,并提出一些改进建议。     

双荷载箱自平衡法在超长桩基承载力测试中的应用

在黄河中游山西小北干流范围,地下以砂土、粉质黏土层等物理力学指标较低的地层为主。在这种复杂的地质条件下,为保证桥梁桩基承载力和上部结构的安全性要求,设计多采用大直径超长桩为主,施工难度较大,造价较高。双荷载箱自平衡法是指根据试验方案规定,在桩身特定位置依次嵌入两个荷载箱,然后按照加载试验方案对荷载箱进行逐级分段加载,分别得出3段桩身的承载力,可以解决超长桩基试桩试验中的很多问题,为桩长优化设计提供数据支撑,具有广泛的应用前景。     

Price monotonicity violations during stock market crashes: Evidence from the SSE 50 ETF options market

This study empirically tests whether price violations, as defined by Bakshi, Cao, and Chen (2000), show different patterns in response to market shocks. Specifically, we analyze the Chinese options market during a period covering a stock market crash and a series of trading restrictions in the Chinese derivatives markets. Our results confirm the significant changes of the defined violations in the face of unexpected shocks, and more importantly, we interpret such variations from the perspective of information spillovers. Our findings suggest that the stock market crash prompts informed traders in the Chinese options market to frequently adjust their positions on put options, exacerbating the misunderstandings and overreactions to new information. Further, the regulatory shock in the derivatives markets diminishes the efficiency of information incorporation for both options and spot markets but does not affect the dominance of the Chinese options market in price discovery.     

一种级联两箱通用数字预失真器及其辨识算法

提出了一种由单形规范线性分段(SCPWL)函数与记忆多项式级联的数字预失真器,并给出了复数域两步最小二乘参数辨识算法。不同于以往一种预失真器适用一种功放模型的情况,所提的预失真算法利用SCPWL函数的分段特性以及记忆多项式的非线性记忆特性,在完成参数辨识的同时自动地调整结构,可适用于传统以及强非线性新型功放模型的线性化补偿。将所提预失真器分别应用于传统记忆多项式、两箱模型以及新型包络跟踪功放。经过计算机仿真,功放输出的幅频特性和频谱曲线表明所提预失真器能够有效地补偿多种功放的非线性特性。算法仿真比较结果也表明,针对包络跟踪功放,所提复数两步最小二乘算法的邻道泄漏比(ACLR)可改善约35 dB,性能优于最小均方(LMS)类算法约30 dB。     

Derivative disclosures and managerial opportunism

Derivatives are increasingly used by managers not only to hedge risks but also to pursue nonhedging activities for fulfilling opportunistic incentives. The Statement of Financial Accounting Standards No. 161 (SFAS 161) requires firms to disclose their objectives and strategies for using derivatives. Using the adoption of this standard, we examine whether and how derivative disclosures influence managerial opportunistic behavior. We employ insider trades and stock price crash risk to capture managerial opportunism. Applying a difference-in-differences research design with hand-collected data on derivative designations, we find that, after the implementation of SFAS 161, derivative users that comply with SFAS 161 experience a significantly greater decrease in both insider trades and stock price crash risk, compared with a matched control sample of nonderivative-users. We further provide evidence to suggest that SFAS 161 curbs managerial opportunism via reducing information asymmetry between corporate insiders and outside investors and enhancing the effectiveness of derivative hedging.     

确保BZS空腹复合楼板施工质量探析

通过对空腹复合无梁楼盖新技术的应用,在工程实例中采用PDCA循环质量管理,找出影响空腹复合楼板质量的主要问题,并展开原因分析,确定改进对策后实施,总结了空腹复合楼板的施工技术及施工经验。     

锈蚀钢筋混凝土薄壁箱梁非线形分析

薄壁箱梁结构由于其结构轻,刚度大,在结构工程中得到了广泛的应用.钢筋锈蚀是影响混凝土结构耐久性的重要因素,为了正确评估钢筋锈蚀后构件的裂缝发展情况,本文利用大型有限元软件ANSYS通过对锈蚀钢筋混凝土薄壁箱梁的非线性分析,得到了锈蚀构件的裂缝的变化规律.     

现浇连续箱梁合拢段施工技术

随着大跨径现浇连续箱梁桥成为跨越大江、大河、山谷的主选桥梁形式之一,现浇连续箱梁主要重难点部分合拢段的混凝土温度控制是非常重要的。着重介绍了安家山河大桥施工悬臂合拢段的施工前准备及施工中合拢段的施工技术。