Attitude Synchronization of Rigid Spacecraft with Inertia Uncertainties and Environmental Disturbances

2018 ◽  
pp. 259-272 ◽  
Author(s):  
Yuanqing Xia ◽  
Jinhui Zhang ◽  
Kunfeng Lu ◽  
Ning Zhou
Keyword(s):  
Environmental Disturbances ◽  
Rigid Spacecraft ◽  
Attitude Synchronization

Distributed Fixed-time Attitude Synchronization Control for Multiple Rigid Spacecraft

2019 ◽  
Vol 17 (5) ◽  
pp. 1117-1130 ◽  
Author(s):  
Wei-Shun Sui ◽  
Guang-Ren Duan ◽  
Ming-Zhe Hou ◽  
Mao-Rui Zhang
Keyword(s):  
Fixed Time ◽  
Synchronization Control ◽  
Rigid Spacecraft ◽  
Attitude Synchronization

CONTRIBUIÇÃO AO CONHECIMENTO DA AVIFAUNA DO MUNICÍPIO DE TAQUARA, RIO GRANDE DO SUL

2019 ◽  
Vol 2 ◽  
pp. 28
Author(s):  
Marcelo Pereira de Barros ◽  
Ana Paula Lima da Silveira ◽  
Bruna Reis Ferreira
Keyword(s):  
Rural Areas ◽  
Rio Grande ◽  
Bird Community ◽  
Frequency Of Occurrence ◽  
Diverse Group ◽  
Rio Grande Do Sul ◽  
Natural Ecosystems ◽  
Environmental Disturbances ◽  
Environmental Pressures ◽  
Hydrographic Basin

As aves destacam-se dentro dos vertebrados por serem um grupo diverso e adaptado a diferentes ambientes, a composição da comunidade de aves de um determinado local é um importante bioindicador ambiental, pois ela reflete alterações recentes ou pretéritas de determinada área. Na Bacia Hidrográfica do Rio dos Sinos, as pressões sobre os remanescentes de ecossistemas naturais são intensas em decorrência da urbanização crescente, do estabelecimento de indústrias e da ampliação das fronteiras agrícolas, esses fatores associados geram a redução e fragmentação de habitats, com impactos irrecuperáveis para a flora e a fauna. Devido à escassez de dados sobre a avifauna do município de Taquara, o presente estudo teve como objetivo levantar informações sobre o grupo, listando as espécies de aves locais. Entre agosto de 2016 e junho de 2017 foram realizadas quatro amostragens mensais em duas áreas rurais do município, totalizando 44 campanhas de observação e 132 horas de esforço amostral. As espécies foram identificadas e classificadas conforme sua frequência de ocorrência mensal, em espécies comuns e raras. Foram registradas 133 espécies distribuídas em 47 famílias, o que representa mais de 20% das espécies ocorrentes para o estado. Ao longo do período amostrado, 90 espécies foram classificadas como comuns e 47 consideradas raras para as áreas pesquisadas.Palavras-chave: Aves. Bacia hidrográfica do Rio dos Sinos. Preservação.ABSTRACTBirds stand out within vertebrates because they are a diverse group adapted to different environments. The composition of the bird community of a certain place is an important environmental bioindicator since it reflects recent or previous environmental disturbances of a certain area. In the Sinos River Basin, environmental pressures on the remnants of natural ecosystems are intense as a result of increasing urbanization, the establishment of industries and expansion of agricultural frontiers which generate habitat reduction and fragmentation with irrecoverable damages on flora and fauna. Due to the scarcity of data on the avifauna of the municipality of Taquara, the present study aimed to gather information and list the species of local birds. Between August 2016 and June 2017, four monthly samplings were carried out in two rural areas of the municipality, totaling 44 observation campaigns and 132 hours of sample effort. The species were identified and classified as common and rare according to their frequency of occurrence. There were 133 species distributed in 47 families, representing more than 20% of the species that occurred in the state. During the sampled period, 90 species were classified as common and 47 were considered rare for the areas surveyed.Keywords: Birds. Hydrographic basin of Sinos River. Preservation.

scholarly journals 422 Million intrinsic quality factor planar integrated all-waveguide resonator with sub-MHz linewidth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Matthew W. Puckett ◽  
Kaikai Liu ◽  
Nitesh Chauhan ◽  
Qiancheng Zhao ◽  
Naijun Jin ◽  
...  
Keyword(s):  
Quality Factor ◽  
High Capacity ◽  
Precision Spectroscopy ◽  
Narrow Linewidth ◽  
Waveguide Resonator ◽  
Environmental Disturbances ◽  
Fiber Communications ◽  
Intrinsic Quality ◽  
Quality Factor Q ◽  
Quantum Photonics

AbstractHigh quality-factor (Q) optical resonators are a key component for ultra-narrow linewidth lasers, frequency stabilization, precision spectroscopy and quantum applications. Integration in a photonic waveguide platform is key to reducing cost, size, power and sensitivity to environmental disturbances. However, to date, the Q of all-waveguide resonators has been relegated to below 260 Million. Here, we report a Si3N4 resonator with 422 Million intrinsic and 3.4 Billion absorption-limited Qs. The resonator has 453 kHz intrinsic, 906 kHz loaded, and 57 kHz absorption-limited linewidths and the corresponding 0.060 dB m−1 loss is the lowest reported to date for waveguides with deposited oxide upper cladding. These results are achieved through a careful reduction of scattering and absorption losses that we simulate, quantify and correlate to measurements. This advancement in waveguide resonator technology paves the way to all-waveguide Billion Q cavities for applications including nonlinear optics, atomic clocks, quantum photonics and high-capacity fiber communications.

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