Mid to late Cambrian thrombolites and maze‐like maceriate reefs from the western North China Platform, Wuhai, Inner Mongolia, northwestern China, occur in the middle of a succession dominated by thin‐bedded lime mudstone‐shale/marlstone alternations, and are laterally surrounded by limestone conglomerate and/or grainstone. Thrombolite, characterized by meter‐scale lenticular mounds composed of millimeter‐ to centimeter‐scale mesoclots and wackestone matrix, occurs in the lower middle part of the sequence. Thrombolite mesoclots are composed of microstromatolites with alternating dark gray and light gray micritic laminae. The maze‐like maceriate reefs occur in the middle to the upper part of the sequence, commonly forming lenticular mounds up to 1 m thick. They are characterized by centimeter‐ to decimeter‐scale branched maze‐like structures, whose biogenic portions (maceria) are selectively dolomitized. The maceriae are composed of poorly preserved microstromatolites and siliceous sponges. Inter‐macerial sediments consist of lime mud and scattered bioclasts. These Wuhai reefs are generally similar to but older than various other Cambrian reefs previously reported from the Shandong region, northeastern China.
In this paper, an optical structure for the aircraft was considered and its vibrational characteristics and weight were optimised using the robust design technology. To acquire the vibration characteristics and the stable line of sight, modal analyses were performed to the optical structure using the commercial multi-body dynamics programme ADAMS. Four design variables, were selected to investigate the vibrational characteristics as well as lightweight effect using the L9(34) type orthogonal array. To fulfill the natural frequency criterion (75Hz), the proper values of each design variable were suggested.
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