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  • Author: Shengxiang Huang x
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Abstract

The immersed tunnel which is composed of elements has drawn more attention nowadays because of new advancements and developments. The elements are prefabricated somewhere else and floated to the tunnel site to be sunk into the prepared trench. Each element must line up exactly for the watertight gaskets to seal properly. The HZM immersed tunnel, a key part of the Hong Kong-Zhuhai-Macao Bridge (HZMB) that crosses the Pearl River Estuary and links Hong Kong to the east, and Zhuhai and Macao to the west, is 6.7 km long, one of the longest immersed tunnel ever realized in the world. For the construction of such a mega immersed tunnel, particular care should be taken in the perspective of geodetic control. This paper described the design and implementation of the geodetic basis and hierarchical surface control networks. And to decrease the influence of lateral refraction and to improve the configuration strength and increase the number of redundant observation compared with traverse, the design of underground surveying network named duo-linear joint chain and the results of gyro checks are presented. In the end HZM immersed tunnel surveying data is analyzed and the performance of the control networks is demonstrated.

Abstract

Thomassen described all (except finitely many) regular tilings of the torus S 1 and the Klein bottle N 2 into (3,6)-tilings, (4,4)-tilings and (6,3)-tilings. Many researchers made great e orts to investigate the crossing number of the Cartesian product of an m-cycle and an n-cycle, which is a special kind of (4,4)-tilings, either in the plane or in the projective plane. In this paper we study the crossing number of the hexagonal graph H 3, n (n ≥ 2), which is a special kind of (3,6)-tilings, in the projective plane, and prove that

crN1(H3,n)={0,n=2,n-1n3.

Abstract

There is extremely strict precision requirement for the lateral breakthrough error of long immersed tunnel in the offshore island and tunnel project, but the point location layout range of the outer plane control network is limited in the artificial island, and the space inside the tunnel is long and narrow, which is not conducive to high-precision through-measurement control. In order to further reduce the influence of the error of the plane control network on the lateral breakthrough error of the immersed tunnel, a mathematical model of the influence of the lateral breakthrough error caused by the orientation direction of the outer control point and the position of the breakthrough point has been established through the theoretical analysis in this study, and the favorable orientation directions and the favorable penetration point are analyzed. It is suggested through simulation analysis that the direction that is as consistent with that from the entrance (outlet) point to the penetration point as possible is as the advantageous orientation, which could minimize the lateral penetration error and ensure high-precision rendezvous and docking of the immersed tunnel. This study is instructive for similar engineering practices.

Two new stilbenoids cajanotone and cajanamide A (1-2), together with another six known ones (3- 8) and four known dihydroflavones (9-12), have been isolated from the leaves of Cajanus cajan. Their structures were elucidated based on spectroscopic studies. A possible pathway to the new compounds 1 and 2 has been proposed. In vitro cytotoxicities of selected compounds against cancer cell lines HepG2, MCF-7 and A549 have been evaluated. Compounds 7 and 8 show strong cytotoxity against all the tested cell lines (with IC50 values in the range of 3.5 - 6.0 μM), and compounds 1 and 3 showed strong to moderate activity against the three cell lines.