A new method for extrapolating the load-displacement response of drilled shaft foundations for interpretation of side capacity

In this study, the side capacity of drilled shaft foundations is estimated from partially-mobilized load–displacement field data using a new method in the extrapolation of load–displacement response. A dataset of 138 bi-directional load tests is used to evaluate the degree of mobilization of unit side resistance. A total of 612 unit side-resistance curves obtained from measured strain gauge recordings are utilized in this study. The proposed extrapolation approach is based on a new technique, the Double Tangent method, characterizing the extent of mobilization for each unit side-resistance curve. Roughly, 12% of the dataset exhibits a fully-mobilized load–displacement response, with the remainder exhibiting varying degrees of a partially-mobilized response. Fully-mobilized records are further characterized using the Double Tangent method over different ranges of mobilization, resulting in four regression models based on predominant soil types. Each model is assessed statistically, and a global regression model is found suitable to predict maximum unit side resistance. The global model is further validated using two independent load test datasets, comparing measured values of unit side resistance against predicted values. The model is then used to predict maximum unit side resistance for all partially-mobilized data within the dataset, and the results are compared to two extrapolation techniques currently used in practice. The corresponding resistance-displacement response is extrapolated using a proposed asymptotic curve-fitting function for side resistance, and an example extrapolation is illustrated to showcase how the proposed method can be used in engineering practice.     

2种侧围加强内框总成检具结构对比分析

概述了侧围加强内框总成与周边零件的匹配关系,从检具操作的人机工程出发,描述了侧围加强内框总成检具的2种定位方式和结构设计,对比了2种定位方式对于检测结果的影响,总结了其优点和弊端,结果表明侧围加强内框总成检具采用车内方向朝下的定位方式效果更好。     

Notwendigkeit und Vermarktung von Flexibilitätsoptionen im Energiesystem der Zukunft

Demands on production, distribution and consumption of electrical energy change fundamentally with the energy revolution. Energy purchasing costs for inflexible consumers are rising and proceeds of inflexible producers are sinking. Companies are able to reduce costs by marketing operational flexibility options. This article sets out the need of flexibility in the energy system and the new marketing options. Flexibility potentials within infrastructure plants of a chemical park are analyzed, evaluated regarding marketing and activated in the presented research project FlexChemistry.     

计及RSC控制的DFIG短路电流直流分量解析表达

现有文献针对计及转子变流器(RSC)控制的双馈感应风电机组(DFIG)定子短路电流解析表达,将定子磁链当作一阶直流衰减分量或忽略功率外环控制。基于DFIG电压、磁链和RSC控制方程,得到定子电流关于定子电压和定子功率的传递函数,提出定子电流的精确解析表达式。基于RSC内、外环PI参数关系,推导直流分量衰减时间常数和角频率关于PI参数的表达式。分析了RSC内外环PI参数对定子电流直流衰减分量的影响。仿真结果验证了解析表达式的准确性,为PI参数选取和保护装置测量、整定提供依据。     

Analysis of the convective heat transfer and flow behavior around two counter‐rotating side‐by‐side cylinders

This study presents details of the heat and fluid flow around two counter‐rotating cylinders. For this goal, three different nondimensional gap spaces such as G/D = 1.5, 2.0, and 3.0 are examined in the constant Reynolds number of 200 and Prandtl number of 7.0. In addition, computations are carried out at various nondimensional rotating speeds (R.S) in the range from 0 to 4. The obtained results are validated against the available data in the open literature for stationary cases. The results showed that the flow structure, vortex shedding process, and exerted forces on the cylinders strongly depended on the R.S and G/D. Reductions of the drag coefficients are observed for both cylinders with increasing the R.S due to suppression of the wake downstream of the cylinders at low R.S and eliminating the vortex shedding process at high R.S. Finally, it is demonstrated that, regardless of the G/D value, increasing the R.S diminishes dramatically the convective heat exchange rate between the cylinders and fluid flow.     

1226工作面切顶卸压沿空成巷技术应用研究

为解决掘进成本较高、接替紧张等问题,基于1226工作面地质条件,对运输巷进行切顶卸压沿空留巷设计,主要包括切顶预裂缝、恒阻大变形锚索和巷道支护参数的设计,取得较好效果。     

Ex post demand information sharing between differentiated suppliers and a common retailer

We consider ex post demand information sharing in a two-echelon supply chain in which two suppliers sell differentiated products through a common retailer. We model three scenarios of information sharing to characterise the conditions under which information sharing may benefit or hurt different players: (1) no supplier is informed; (2) only one supplier is informed; and (3) both suppliers are informed. We find that the retailer may voluntarily share the low demand information when the product differentiation and demand magnitude satisfy certain conditions. In contrast, the retailer has no incentive to share the high demand information, even though this information benefits the suppliers. To achieve information sharing, we propose a side payment mechanism, which allows benefitted players to subsidise hurtful players. Finally, we extend our model by considering a situation where the suppliers have limited capacity and may invest to ramp up production capacity to satisfy a high demand.     

正偏心正交车铣精加工切削层几何形状研究

针对未考虑正偏心正交车铣切削层几何形状而导致难以全面反映正交车铣切削层几何形状变化规律的问题，基于正交车铣运动规律，在不考虑动力学影响的情况下，对切削层的形成过程进行了静态分析。建立的正偏心正交车铣切削层几何形状的解析模型涉及铣刀侧刃和底刃的切入/切出角度、切削厚度和切削深度。通过试验验证了该解析模型的正确性，并分析了切削参数对铣刀切削层的影响。研究结果为正偏心正交车铣切削层几何形状的变化提供了定量的分析依据，为切削力和颤振的研究提供了理论指导。     

四川盆地龙门山北段隐伏构造带特征及其油气勘探意义

2014年以来,四川盆地西北部(以下简称川西北)龙门山山前带双鱼石地区上古生界天然气勘探获得重大发现,先后在中二叠统栖霞组、中泥盆统观雾山组钻获多口工业气井。随着勘探工作的稳步推进,深入开展龙门山逆冲推覆构造前锋带—山前带构造特征研究,是认识该区上古生界气藏特征、拓展油气勘探领域的重要前提。为此,基于新部署的线束三维地震、重磁电资料以及ST9等井的实钻成果,解剖了龙门山逆冲推覆构造前锋带—山前带的构造特征,进而分析了该区隐伏构造带的构造特征、天然气成藏条件和勘探前景。结果表明:(1)龙门山逆冲推覆构造前锋带(1)号隐伏断裂之下发育大型隐伏构造带,其地层受挤压褶皱变形,发育下三叠统嘉陵江组以下的海相地层;(2)由南到北(1)号断裂底部滑脱层位由浅变深,从南部的寒武系滑脱,向北部逐渐转换为基底卷入,古生界及其以上地层整体抬升,越向北抬升幅度越大,断裂上下盘之间的位移距离、褶皱幅度也越大,北部相对南部上古生界构造整体抬升约1 500 m;(3)在剑阁以西—广元地区,(1)号断裂东侧整体表现出"三级台阶"的构造格局。结论认为:龙门山逆冲推覆构造前锋带(1)号断裂下盘隐伏构造带面积达1 800 km2,具有优越的天然气成藏条件,其中观雾山组和栖霞组储集条件、保存条件好,是川西北深层海相层系天然气勘探拓展寻找新突破的重要领域,具有现实的油气勘探意义。