兼具負有效質量密度和負有效體彈模量的聲學功能材料

本發明涉及兼具負有效品質密度和負有效體彈模量的聲學功能材料，其具有至少一個管狀部分、以及密封該管狀部分兩端的前薄膜和後薄膜。 所述密封該管狀部分的前薄膜和後薄膜將該管狀部分充分密封，從而建立起由該管狀部分和所述前薄膜及後薄膜限定的密封或受限的封閉流體空間，並杜絕因聲學振動而導致的流體流失或流體攝入。 在所述前薄膜和後薄膜上設置一對片狀物，使得這對片狀物中的一者大體上處於所述前薄膜的中心，而另一者大體上處於所述後薄膜的中心

消聲結構

一种消声面板由实质透声的平面刚性框架构成，该刚性框架分成多个单独的大体二维单元。挠性材料薄片固定至刚性框架，以及，多个薄块固定至挠性材料薄片，使得每一个单独单元设置有各自的薄块，以建立共振频率，该共振频率由框架的平面几何特性、挠性材料的挠性、以及薄块限定。单元分成至少两种不同类型的单独单元，构造成使得，由不同类型单独单元的第一类单元发出的声波，与由不同类型单独单元的第二类单元、或不同类型单独单元的聚集体发出的声波，形成消声模式。A sound attenuation panel is configured with a substantially acoustically transparent planar, rigid frame divided into a plurality of individual, substantially two-dimensional cells. A sheet of a flexible material is fixed to the rigid frame, and a plurality of platelets fixed to the sheet of flexible material such that each individual cell of the plurality of cells is provided with a respective platelet to establish a resonant frequency, the resonant frequency defined by the planar geometry of the individual cells, the flexibility of the flexible material and the platelets. The cells are divided into at least two different types of the individual cells, configured so that sound waves emitted by a first type of said different types of individual cells establishes a sound cancellation pattern with sound waves emitted by a second type of said different individual cells or an aggregation of different types of the individual cells

Indicator system for assessing mangrove ecological degradation and a case study of the Zhangjiang Estuary

通过总结目前红树林面临的各类生态退化机制,利用“压力-状态-响应(PSr)“分析模型,构建了红树林生态退化机制评估指标体系,并应用于福建省漳江河口红树林生态系统的案例研究.评价结果显示:漳江河口红树林生态退化压力仍处在较小的范围内,主要压力源来自生物入侵以及海岸带水产养殖和围垦;对影响显著的生态退化因子已经采取了有效的控制措施;保持并加强保护措施,将有助于当地红树林生态系统在未来维持稳定的状态.An assessment indicator system was constructed based on a summary of various mangrove ecological degradation mechanisms using a 'Pressure-State-Response(PSR)' model.This model was then applied to a case study of mangroves in the Zhangjiang Estuary of Fujian Province.The results showed that the mangrove is facing small ecological stress that mainly stems from alien species invasion,coastal reclamation and aquaculture.Several influential ecological degradations have been effectively controlled by conservation measures,which will contribute to maintaining the stable state of the mangrove in the near future.国家908专项资助项目(908-02-04-04);福建省908专项资助项目(FJ908-02-02-04

兼具负有效质量密度和负有效体弹模量的声学功能材料

本发明涉及兼具负有效质量密度和负有效体弹模量的声学功能材料，其具有至少个管状部分、以及密封该管状部分两端的前薄膜和后薄膜。所述密封该管状部分的前薄膜和后薄膜将该管状部分充分密封，从而建立起由该管状部分和所述前薄膜及后薄膜限定的密封或受限的封闭流体空间，并杜绝因声学振动而导致的流体流失或流体摄入。在所述前薄膜和后薄膜上设置对片状物，使得这对片状物中的者大体上处于所述前薄膜的中心，而另者大体上处于所述后薄膜的中心。The present invention relates to an acoustic functional materials with the negative effective mass density and elastic modulus of the negative active material having at least one tubular portion, and the sealing of the film before and after the film ends of the tubular portion. The sealing of the tubular film before and after the film portion of the tubular seal portion sufficiently to establish a fluid space is closed by the front portion and the tubular film and sealing the film after a defined or limited, due to acoustic vibrations and eliminate the cause fluid loss or fluid intake. Film disposed on the front and back of the film sheet, which is generally at the center so that the center of the front sheet of the film in those, and the other substantially at the back by the film

Research on Synergy Pursuit Strategy of Multiple Underwater Robots

This paper presents a synergy pursuit strategy that multiple underwater robots pursue a single moving target based on finite state machine. The processes of the pursuit are defined as seven different states, and to implement each state, the corresponding strategies are designed. As the strategy for each state is implemented by a corresponding formation control, a synergy control law is also designed for multiple underwater robots. In the design of the pursuit strategy, the definition of encirclement is put forward for the underwater robots. Furthermore, the proof that a point is encircled by other points on the plane is given. To solve the problem of the concealment in the tracking and the pursuit, a semicircular pursuit strategy and a circular pursuit strategy are also proposed. Finally, based on this pursuit strategy, the simulation of whole process is carried out with the MOOS(Mission Oriented Operating Suite) platform, and the effectiveness of the semicircular and circular pursuit strategy are verified by lake experiment with practical robots. The results of simulation and lake experiment prove that this pursuit strategy can realize synergy tracking and pursuit for a single moving target under the given conditions.</p