复杂异曲面吊顶技术研究

近年来,随着社会不断进步发展,人们对生活品质要求不断提升,公共交通旅客站房不仅需要具备通行功能,还需具备艺术美观性、文化元素,建造设计师应对公共交通旅客站房设计更加复杂的造型以凸显艺术美观性及文化元素。本文讲述了复杂异曲面吊顶施工方法,通过工程实例分析复杂异曲面吊顶施工控制要点、复杂异曲面吊顶施工精度控制方法,能有效提高施工的便捷性,具有良好的经济性,便于类似工程借鉴使用。

大跨度悬挑异形屋盖钢结构设计分析研究

本文通过体育场、体育馆、训练馆和游泳馆等屋盖异形大跨度悬挑钢结构设计研究,对结构设计荷载进行必要预留,避免了后期吊装时因为预留荷载不足,进行大规模改造的问题,不仅节省了大量资金,也极大的缩短了工期。

Regional magnetic anomaly fields:3D Taylor polynomial and surface spline models

We used data from 1960.0,1970.0,1980.0,1990.0,and 2000.0 to study the geomagnetic anomaly field over the Chinese mainland by using the three-dimensional Taylor polynomial（3DTP） and the surface spline（SS） models.To obtain the pure anomaly field,the main field and the induced field of the ionospheric and magnetospheric fields were removed from measured data.We also compared the SS model anomalies and the data obtained with Kriging interpolation（KI）.The geomagnetic anomaly distribution over the mainland was analyzed based on the SS and 3DTP models by transferring all points from 1960.0-1990.0 to 2000.0.The results suggest that the total intensity F anomalies estimated based on the SS and KI for each year are basically consistent in distribution and intensity.The anomalous distributions in the X-,Y-,and Z-direction and F are mainly negative.The 3DTP model anomalies suggest that the intensity in the X-direction increases from-100 nT to 0 nT with longitude,whereas the intensity in the Y-direction decreases from 400 nT to 20 nT with longitude and over the eastern mainland is almost negative.The intensity in the Z-direction and F are very similar and in most areas it is about-50 nT and higher in western Tibet.The SS model anomalies overall reflect the actual distribution of the magnetic field anomalies;however,because of the uneven distribution of measurements,it yields several big anomalies.Owing to the added altitude term,the 3DTP model offers higher precision and is consistent with KI.

Optimization of process parameters to maximize ultimate tensile strength of friction stir welded dissimilar aluminum alloys using response surface methodology

Aluminium alloys generally present low weldability by traditional fusion welding process. Development of the friction stir welding （FSW） has provided an alternative improved way of producing aluminium joints in a faster and reliable manner. The quality of a weld joint is stalwartly influenced by process parameter used during welding. An approach to develop a mathematical model was studied for predicting and optimizing the process parameters of dissimilar aluminum alloy （AA6351 T6-AA5083 Hlll）joints by incorporating the FSW process parameters such as tool pin profile, tool rotational speed welding speed and axial force. The effects of the FSW process parameters on the ultimate tensile strength （UTS） of friction welded dissimilar joints were discussed. Optimization was carried out to maximize the UTS using response surface methodology （RSM） and the identified optimum FSW welding parameters were reported.

Theoretical Studies on Dihedral Angle-Bending Isomers of M2Pt2^0/- Clusters

The structures and electronic properties of the gaseous M2Pt20/-clusters(M represents the alkaline earth metal)were investigated using the density functional theory(B3LYP and PBE0)and wave function theory(SCS-MP2,CCSD and CCSD(T)).The results indicate that the D2 hisomers with the planar structures are more stable than the C2v isomers with smaller dihedral angles and shorter Pt-Pt bond lengths.The mutual competition of M(s,p)-Pt(5d)interaction and Pt-Pt covalent bonding contributes to the different stabilizations of the two kinds of isomers.The M(s,p)-Pt(5d)interaction favors the planar isomers with D2 hsymmetry,while the Pt-Pt covalent bonding leads to the C2 visomers with bending structures.Two different crossing points are determined in the potential energy curves of Be2Pt2 with the singlet and triplet states.But there is just one crossing point in potential energy curves of Ra2Pt2 and Ca2Pt2-because of flatter potential energy curves of Ra2Pt2 with the triplet state or Ca2Pt2-with quartet state.The results reveal a unique example of dihedral angle-bending isomers with the smallest number of atoms and may help the understanding of the bonding properties of other potential angle-bending isomers.

A Two-Step Outlier Removal Procedure for Surface Reconstruction

Outliers in point clouds affect the performance of surface reconstruction directly. Most of outlier removal methods just remove those outliers far away from the real surface and are only applied to handle watertight surface. In this paper, a two-step outlier removal procedure is proposed to filter the point clouds acquired from the gray code and line-shifting technique. The first step is to remove the outliers far away from the real surface. Some feature points are extracted from the point clouds to construct an initial surface. The points with distances to the initial surface greater than a given threshold are removed as distant outliers. The retained points are linked into lines in each structured light sheet using their Voronoi diagrams. Some of lines which are very close to the real surface are removed as near outliers in the second step. The experimental results show that the proposed method is very effective in removing outliers for surface reconstruction.

Stability of hypersurface sections of quadric threefolds

Let S be a complete intersection of a smooth quadric 3-fold Q and a hypersurface of degree d in P4.We analyze GIT stability of S with respect to the natural G=SO(5,C)-action.We prove that if d 4 and S has at worst semi-log canonical singularities then S is G-stable.Also,we prove that if d 3 and S has at worst semi-log canonical singularities then S is G-semistable.

Ruan's conjecture on singular symplectic flops of mixed type

In this paper,we study the global singular symplectic flops related to the following affine hypersurface with cyclic quotient singularities,Vr,b={(x,y,z,t)∈C4|xy-z2r+t2=0}/μr(a,-a,b,0),r 2,where b=1 appears in Mori’s minimal model program and b=1 is a new class of singularities in symplectic birational geometry.We prove that two symplectic 3-orbifolds which are singular flops to each other have isomorphic Ruan cohomology rings.The proof is based on the symplectic cutting argument and virtual localization technique.

A note on finite abelian covers

We prove that any abelian cover over a smooth variety is defined by some cyclic equations. From the defining equations, we compute explicitly the normalization, branch locus, ramification indices, global invariants, and the resolution of singularities. As an application, we construct a new algebraic surface which is the quotient of ball.