水电站建成后分流河段水位流量关系的变化

在分流河段修建水电工程，因受工程建设的影响，其下游的水位流量关系曲线将不再是单一曲线，而是一束以全断面流量为参数的曲线组。这束曲线中的任一曲线应通过３个特征点。曲线起点、天然分流点、曲线终点，这３个点确定后，即可推求不同总流量情况下的水位流量关系曲线。     

A functional time series analysis of forward curves derived from commodity futures

We study forward curves formed from commodity futures prices listed on the Standard and Poor’s-Goldman Sachs Commodities Index (S&P GSCI) using recently developed tools in functional time series analysis. Functional tests for stationarity and serial correlation suggest that log-differenced forward curves may be generally considered as stationary and conditionally heteroscedastic sequences of functions. Several functional methods for forecasting forward curves that more accurately reflect the time to expiry of contracts are developed, and we found that these typically outperformed their multivariate counterparts, with the best among them using the method of predictive factors introduced by Kargin and Onatski (2008).     

中国高技术产业重心与经济重心变动轨迹比较

高技术产业是国民经济中重要的战略性先导产业。文章借鉴并运用经济重心研究方法对中国高技术产业及国民经济整体空间分布格局演化做了系统研究,通过刻画和比较分析我国1995--2009年高技术产业重心和经济重心变动轨迹,发现我国高技术产业空间分布不平衡,特别是东西横向不均衡程度加剧,高技术产业对国民经济整体发展影响有限,提出有必要加大对我国高技术产业的政策扶持力度和区域经济均衡发展调整力度,实现高技术产业带动下的我国国民经济全面协调可持续的科学发展。     

Neglected dynamics in panel data models; consequences and detection in finite samples*

The bias of various estimators for static cross-section and panel data models is assessed in a simulation study, where the actual data generating process is a dynamic adjustment mechanism with random individual effects. It is concluded that the consequences of incorrectly estimating a static model can be rather serious. Therefore, it is important to have an accurate technique available for the detection of dynamics. Two exact similar tests for the presence of a lagged dependent variable in panel data models are developed; in some simulation experiments these tests outperform standard asymptotic test procedures. Empirical results on Engle curves for food illustrate the above issues.     

Reflections on the Structure and Origin of Pareto Income Distributions

The essay takes the reader on a voyage of exploration with the aim of discovering the origin of Pareto-curves. It shows with thought-experiments backed up by computer-simulation the generation of log-normal curves in detail. Extending forward this conceptual trajectory, it arrives via a quasi-Newtonian fluxion-insight – infinitessimal differential integration – at a novel mathematical concept: Pareto-curves are simply special log-normal curves where a large number of random-factors interacted and impacted at their genesis (the author called it the Kopp-effect).     

南水北调穿黄隧洞内衬预应力锚索应力应变试验研究

南水北调中线穿黄隧洞内衬张拉,采用弧形垫座将内衬预应力锚索导出预留槽,只用一台千斤顶实现无台座张拉,这在盾构隧洞工程中属首次应用,结构创新、工艺复杂可借鉴的资料较少。为了验证结构设计的合理性和可靠性,完善施工工艺,确保在隧洞衬砌中成功应用,通过穿黄隧洞衬砌1∶1仿真模型试验,对内衬钢绞线在张拉过程中应变规律、应力损失、锚束之间的相互影响及锚索与波纹管间的摩阻系数等要素进行研究分析。试验结果显示张拉锚固端应力总损失（包括锚具损失和锚索回缩损失）小于35%;锚具锁定后最大应力为1 044.25 MPa;预应力锚索张拉对相邻锚索的影响较小;锚索与管道间的摩阻系数在规范范围内。     

赣江下游河段设计最低通航水位计算方法

用保证率频率法计算赣江下游河段设计最小通航流量，再从近几年枯水期水位流量关系曲线上查得对应于该流量的水位，即为设计最低通航水位。用该方法计算的设计水位更符合河道的实际情况。     

钢纤维混凝土轴拉应力-应变特性的试验研究

本文采用环氧粘接法对4种纤维混凝土材料进行了轴向拉伸试验，成功地获得了材料的应力-应变全曲线。根据其试验曲线是否出现第二峰值，把纤维分为增强与增韧两大类。通过分析表明：不同的纤维形式对混凝土材料的作用机理有较大的差异。在工程应用中，应根据纤维混凝土材料的用途来选择纤维类型。     

Effect of immobile water content on contaminant transport in unsaturated zone

The effect of immobile water content on contaminant advection and dispersion in unsaturated porous media has been studied using a formulation which assumes that even in the immobile liquid zone, there occurs minor liquid flow. An approach is proposed for computing this liquid velocity. One dimensional numerical simulation is carried out to study the effect of immobile water content on the time of appearance of contaminant at the bottom of an unsaturated column. The numerical model developed is verified using analytical solutions for simple advective-dispersive cases. From the simulations, it was observed that increase in the immobile water content leads to quicker appearance of contaminant.     

Economies of scale and gender discrimination in transition: the case of the Republic of Tajikistan

This article tests for economies of scale and for evidence of discrimination based on gender lines in intra-household consumption allocations using data from the Living Standards Survey in the Republic of Tajikistan (TLSS). Overall results support the existence of household economies of scale in Tajikistan; however, empirical evidence supporting boy–girl discrimination is limited despite anecdotal evidence otherwise.