Multilevel Optimal Design of Prestressed Lightweight Concrete-Steel Platform Structures

The concrete-steel platform structure is rather complicated because it involves such materials as concrete, reinforcing bars, steel, and so on. K the traditional dimension optimization method is employed, the optimal design of the platform will meet many handicaps, even it cannot be implemented at all. The multilevel optimal design approach is an efficient tool for the solution of large-scale engineering structures. In this paper, this approach is applied to the optimal design of a concrete-steel platform, which is formulated as a system level optimal design problem and a set of uncoupled substructure level optimal design problems. The process of optimization is a process of iteration between system level and substructure level until the objective function converges. An illustrative example indicates that this method is effective in the optimal design of concrete-steel platforms.     

Investigation on the Oscillating Buoy Wave Power Device

An oscillating buoy wave power device (OD) is a device extracting wave power by an oscillating buoy. Being excited by waves, the buoy heaves up and down to convert wave energy into electricity by means of a mechanical or hydraulic device. Compared with an Oscillating Water Column (OWC) wave power device, the OD has the same capture vvidth ratio as the OWC does, but much higher secondary conversion efficiency. Moreover, the chamber of the OWC, which is the most expensive and difficult part to be built, is not necessary for the OD, so it is easier to construct an OD. In this paper, a nu-merical calculation is conducted for an optimal design of the OD firstly, then a model of the device is built and, a model test is carried out in a wave tank. The results show that the total efficiency of the OD is much higher than that of the OWC and that the OD is a promising wave power device.     

Silting in the Lower Courses of Tidal Sluices in China

Serious sediment deposition often occurs after the construction of tidal sluices in snrall or medium-sized tidal muddy estuaries, so desilting or dredging is needed to meet the demands of flood diseharge, saltwater retaining, and navigation in those areas. In this paper, the problem of sediment deposition induced by construction of tidal sluices is analyzed.Different problems of silting near tidal sluices for different types of estuaries are summed up. at the same time, corresponding methods are given to solve these probleras, and a few successful examples are also given. The idea of comprehensive regulation and utilization of estuaries is put forward, and some proposals for solution of sediment deposition in this kind of estuaries are made.     

Cumulative Deformation of Soft Clay Under Cyclic Loading

Reconstituted specimens are prepared by means of vacuum preloading. Both static and cyclic triaxial tests are carried out, with the specimens consolidated under different principal stress ratios. A finite element method is put forward for calculating the cumulative deformation of soft clay under cyclic loading.     

古代中西方成矿理论之比较

古代中国和西方对矿物成因之解释都很早。西方早在公元前4世纪,有希腊的亚里斯多德(Aristotle)认为地下矿物是干气和湿气所造成的。中国早在先秦时代,也有《周礼·考工记》认为是“地气”使然。本文详细说明中国和西方16世纪以前的成矿理论,比较其差异,并详细说明两者的优点和缺点,探讨它们之间是否发生相互影响,最后以现代矿床学思想和理论批判中国和西方古代之成矿理论。     

Two Necessary Conditions for the Glacial-Interglacial Cycles in the Quaternary

Milankovitch Theory shows that glacial-interglacial cycles in the Quaternary are related to the variation of solar insolation forcing linked to the earth's astronomical parameters.However,the summer insolation at northern high latitudes,usually considered as the main external forcing for the ice age as Milankovitch pointed out,is marked by the 19- and 23-ka precession periodicities,which is not consistent with the glacial-interglacial cycles.On the other hand,recent studies indicate that the annual mean ...     

Sequences Characterization of Microsatellite DNA Sequences in Pacific Abalone(Haliotis discus hannai)

1 Introduction Microsatellites or simple sequence repeats (SSRs) are tandemly repeated motifs of one to six bases found in all prokaryotic and eukaryotic genomes analysed to date (Zane et al., 2002). Due to their hyper-variable and co-dominant nature, relatively high abundance and random distribution in the genome, microsatellites are among the most efficient class of molecular markers. Such repeats display high polymorphism because of variation in repeat length and can be rapidly analysed t…     

Log evaluation of fractured igneous reservoirs in Songliao Basin

The petrophysical parameters are bad in most igneous reservoirs of Songliao Basin because of the very low porosity and permeability. The evaluation of igneous reservoirs has not been fully studied so far. The current technique of formation evaluation and interpretation used in sedimentary formations face a series of prob- lems and difficulties. In this study, The PCA was used to identify lithology, a multi-mineral model “QAPM” was proposed. “Surface effect” must be considered when evaluating saturation. A software “SIMPLE” was developed and was used to deal with the logging data in over 70 wells with good results were achieved.     

Vertical Distribution of Momentum Exchange Coefficient and Sediment Concentration in Estuarine and Coastal Waters

Vertical structures of momentum exchange coefficient and sediment concentration are the keys in the research on estuarine and coastal suspended sediment transport. Based on the parabolic mixing length distribution pattern,the distribution pattern of vertical momentum exchange coefficient which is suitable for estuarine and coastal waters is constructed. A comparison with steady flow and measured momentum exchange coefficient during one tidal cycle in the Menai Strait of England shows that the result of this...