某箱梁施工过程中开裂事故分析

文章对某铁路桥上简支箱梁在吊装落梁过程中端头面上出现较大裂缝进行分析,发现形成裂缝的主要原因是：在落梁过程中两侧吊杆的不同步松放导致梁体的扭转和施工过程中荷载偏差系数较大。相关计算结果可供同行在进行同类设计受力分析时参考借鉴。     

Locally minimax test of independence in elliptically symmetrical distributions with additional observations

Summary LetX=(X _ij )=(X ₁, ...,X _n )’,X’ _i =(X _i1, ...,X _ip )’,i=1,2, ...,n be a matrix having a multivariate elliptical distribution depending on a convex functionq with parameters, 0,σ. Let ϱ²=ϱ ₂ ^-2 be the squared multiple correlation coefficient between the first and the remainingp ₂+p ₃=p−1 components of eachX _i . We have considered here the problem of testingH ₀:ϱ²=0 against the alternativesH ₁:ϱ ₁ ^-2 =0, ϱ ₂ ^-2 >0 on the basis ofX andn ₁ additional observationsY ₁ (n ₁×1) on the first component,n ₂ observationsY ₂(n ₂×p ₂) on the followingp ₂ components andn ₃ additional observationsY ₃(n ₃×p ₃) on the lastp ₃ components and we have derived here the locally minimax test ofH ₀ againstH ₁ when ϱ ₂ ^-2 →0 for a givenq. This test, in general, depends on the choice ofq of the familyQ of elliptically symmetrical distributions and it is not optimality robust forQ.     

Are CO2 Emission Levels Converging Among Industrial Countries?

Time paths of carbon dioxide emissions intwenty-one industrial countries are examinedfrom 1960–1997 to test for stochastic andconditional convergence. Both panel unit roottests and cross-section regressions areperformed. Overall, we find significantevidence that CO₂ emissions haveconverged.     

Main Reasons Causing Chinese Agricultural Crisis in 1959-1961： Quantitative Test on Yifu Lin＇s Hypothesis

The traditional explanation was found to be inconsistent with the empirical evidence that mainly caused the agricultural crisis in 1959-1961, so Yifu Lin tried to explain this catastrophe through using Game Theory based on ＂one-shot game＂. This paper tested the hypothesis through quantitative test. The results showed that system factors mainly resulted in low productivity, and the natural disaster should not be ignored.     

Multivariate Lagrange Multiplier Tests for Fractional Integration

We introduce a multivariate Lagrange multiplier (LM) test forfractional integration. We derive and analyze the LM statisticand show that it is asymptotically noncentral chi-squared distributedunder local alternatives, and that, under Gaussianity, the LMtest is asymptotically efficient against local alternatives.It is shown that the regression variant in Breitung and Hassler(2002, Journal of Econometrics 110, 167–185) is not equivalentto the LM test in the multivariate case, although it is in theunivariate case. A generalization of the LM test that explicitlyallows for different integration orders for each variable isalso introduced. The finite sample properties of the LM testare evaluated by Monte Carlo experiments which demonstrate thatit is superior to the Breitung and Hassler (2002) test. An applicationto multivariate time series of real interest rates for six countriesis offered, demonstrating that more clear-cut evidence can bedrawn from multivariate tests compared to conducting severalunivariate tests.     

模拟井下环境的下井仪器测试系统

介绍了一种模拟井下环境的下井仪器测试系统。该系统可以模拟石油井下环境的温度和压力等，对下井仪器的性能指标进行测试和实验。实际使用和运行结果表明，该系统达到了设计的功能和技术指标要求。     

云南省边境口岸入境旅游和边境贸易互动关系研究

文章以云南省边境口岸作为研究对象,选取2000~2017年边境口岸入境旅游与进出口贸易相关数据,应用单位根检验、协整检验等方法,研究两者之间的互动关系和协调发展。研究发现:云南省边境口岸入境旅游人数和进出口贸易总额在协整检验之后显示出两者之间存在长期稳定关系;在短期内边境口岸入境旅游人数的变动与进出口贸易总额变动之间是一种单向Granger因果关系;入境旅游发展与进出口贸易两者之间的互动影响是长期的,并且边境口岸进出口贸易总额对入境旅游人数的贡献度远小于边境口岸入境旅游人数对进出口贸易总额的贡献度。鉴于此,提出了推进云南省边境口岸地区入境旅游与边境贸易协调发展的相关建议。     

旋液分离器对泥浆的颗粒分离效率和脱水能力

旋液分离器在泥浆处理领域应用广泛,具有颗粒分级和脱水浓缩的功能,底流颗粒粒径大、浓度高,溢流反之,两者粒径的理论界限称为分离粒径(d_C),实际运转时溢流和底流的颗粒分流会非线性地偏离分离粒径,因此实际粒级效率和脱水率的测试和控制对泥浆处理至关重要。依托泥水盾构工程的泥浆处理系统,使用激光粒度分布测试旋流进浆、底流和溢流粒度组成,结合筛析推演计算全段及各粒级效率,并对比宏观测试计算分离效率,分析旋流正常运转时的泥、水和泥浆的分流关系并提出判别方法。结果表明,该测试计算和判定方法在量程范围内快速有效,颗粒分离偏离分离粒径明显;设备参数不变时,平均效率与脱水率间负相关,且不受颗粒性质和测试方法影响,底部扩口等设备调整可实现两者同时增大。     

变电站配电楼新型装配式基础承载性能试验

为改进现有变电站配电楼基础的性能,提出了一种新式的装配式基础方案,并进行了新型基础的足尺试验,研究其在偏心受压作用下的力学性能。试验结果表明,在设计荷载作用下,仅连接部位有少量钢筋屈服,在基础变阶处产生少量裂缝,倍设计荷载时,部分钢筋屈服并在靠近荷载中心变阶处出现竖向裂缝,此阶段整体未出现明显破损现象,从而体现出其良好的承载力特性;在设计荷载作用下,基础的沉降量满足设计要求,显示出较好的变形性能;在2倍设计荷载时,连接各个组合构件的后浇带未出现明显的破坏。基于本次试验可知,该装配式基础具有良好的承载能力、变形特性,以及具备不错整体性,能够满足基础设计研究。基础底部连接部位是整个装配式基础的薄弱部位,在实际工程设计中,应适当加强构造配筋。     

Detecting bubbles in Hong Kong residential property market

This study uses a newly developed bubble detection method (Phillips, Shi, and Yu, 2011) to identify real estate bubbles in the Hong Kong residential property market. Our empirical results reveal several positive bubbles in the Hong Kong residential property market, including one in 1995, a stronger one in 1997, yet another one in 2004, and a more recent one in 2008. In addition, the method identifies two negative bubbles in the data, one in 2000 and the other one in 2001. These empirical results continue to be valid for the mass segment and the luxury segment. However, this method has also found a bubble in early 2011 in the overall market, and in the mass segment but not in the luxury segment. This result suggests that the bubble in early 2011 in the Hong Kong real estate market was caused primarily by the mass segment under the demand pressure from end-users of small-to-medium sized apartments.