时空数据库中多个最近邻对象的查询算法

在时空数据库中，最近邻查询用于对某个查询对象，在被查询对象中找出离它最近的一个或多个对象。该文在TPR树这一时空索引的基础上，提出了一种高效的最近邻查询算法，能够支持移动对象的多个最近邻对象的查询，并在性能上也有所提高。     

Effect of aging treatment on irradiation-induced segregation of high Mn-Cr steel

To investigate the effect of aging treatment on irradiation-induced segregation of high Mn-Cr steel, specimens for electron-beam irradiation were prepared from the high Mn-Cr austenitic steel which was solution treated at 1 373 K for 1 h and aging treated at 573 K for 1 000 h, respectively. The electron-beam irradiation was performed at 573 K up to doses of 5.4 dpa in a 1 250 kV HVEM and irradiation-induced segregation analyses were carried out by an EDX in a 200 kV FE-TEM. The results show that void formation is not observed in both solution treated and aging treated ones. The amount of Cr segregation at the grain boundary decreases in the aged one; however, that of Mn is not changed in solution treated one.     

Push型LBS应用的实现技术研究*

作为第三代移动通信系统的一种应用——基于定位的服务（LBS）越来越引起移动运营商的重视。如何实现LBS应用也引起了很多人的兴趣。Push型的应用是一种首先由服务方发起,然后向用户发送特定信息的LBS应用,如何实现这种应用成为服务提供者需要研究的课题。提出一种Push型的LBS应用实现方案,对于移动运营商具有现实的参考意义。     

Simulation of water entry of an elastic wedge using the FDS scheme and HCIB method

The hydroelasticity of water entry of an elastic wedge is simulated using a code developed using the flux-difference splitting scheme for immiscible and incompressible fluids and the hybrid Cartesian/immersed boundary method. The free surface is regarded as a moving contact discontinuity and is captured without any additional treatment along the interface. Immersed boundary nodes are distributed inside a fluid domain based on the edges that cross an instantaneous body boundary. Dependent variables are reconstructed at each immersed boundary node with the help of an interpolation along a local normal line for providing a boundary condition for a discretized flow problem. A dynamic beam equation is used for modeling the elastic deformation of a wedge. The developed code is validated through comparisons with other experimental and computational results for a free-falling wedge. The effects of the elastic deformation of the wedge on the pressure fields and time histories of the impact force are investigated in relation to the stiffness and density of the structure. Grid independence test is carried out for the computed time history of the force acting on an elastic wedge.     

Aqueous Extraction and Membrane Techniques Improve Coconut Protein Concentrate Functionality

Functional properties of coconut protein concentrates (CPC) from fresh coconut meat and commercial desiccated coconut meat were assessed and compared with other protein sources. Coconut proteins were extracted from undefatted meats at pH 7 in 0.5M NaCl solution. Protein recovery in the ultrafiltration retentates was about 40% (as % nitrogen) in the starting meats. Water absorption capacities of CPC products were lower than those of soy protein concentrates (SPC) and Na-caseinate, but there was no difference in oil absorption values among CPC, SPC and Na-caseinate. CPC products were more soluble than SPC, but less soluble than Na-caseinate at pH 8 and 10. Emulsifying properties of CPC were superior to those of caseinate and SPC. Total essential amino acids contents of CPC products were lower than caseinate, but similar to SPC.