A kind of novel muhiband antenna with square-nested fractal is proposed and designed, including printed monopole antenna and dipole antenna, which are nested with a series of similar square elements. The antennas can ...A kind of novel muhiband antenna with square-nested fractal is proposed and designed, including printed monopole antenna and dipole antenna, which are nested with a series of similar square elements. The antennas can synchronously operate in multiple frequencies, covering the four required frequencies, 2.4GHz/ 3.5GHz/5.2GHz/5.8GHz, for WLAN/WiMAX application. The antenna surface currents are simulated by CST MWS, a three-dimension full-wave electromagnetic simulator, and the multiband operating mechanism has been explained from analysis of the simulation results. Then the models of the two proposed antennas fed by coplanar waveguide （monopole antenna） and balanced microstripline （dipole antenna）, respectively, have been obtained. Finally, prototypes of the two antennas have been manufactured and measured in anechoic chamber. The results well match the simulation results, which verifies the feasibility of design idea. Moreover, these antennas are miniature and the design idea can be easily applied into other types of nested structure, the features of which make the Proposed antennas have promising application in muhiband fields.展开更多
Artificial nest boxes are placed to attract birds to nest and breed in a specific location,and they are widely used in avian ecology research and in the attraction of insectivorous birds.There is evidence that artific...Artificial nest boxes are placed to attract birds to nest and breed in a specific location,and they are widely used in avian ecology research and in the attraction of insectivorous birds.There is evidence that artificial nest boxes can adversely affect breeding fitness but no great focus has been placed on this issue by researchers.Therefore,we retrieved 321 research papers regarding artificial nest boxes published from 2003 to 2022 and used the'Biblioshiny'program to extract and integrate keywords;we then summarized the adverse effects of artificial nest boxes on avian breeding success.The studies highlighted many drawbacks and misuses in the designing and placement of nest boxes;furthermore,bird attraction was decreased by their inappropriate selection,thus reducing breeding success.Regarding nest box production,there were shortcomings in the construction material,color,smell,and structural design of the boxes used.Nest boxes were also placed at inappropriate densities,locations,orientations,heights,and managed incorrectly.Finally,we propose suggestions for more efficient and safer artificial nest boxes for future use in avian ecology research and bird conservation.展开更多
Urban disaster risks show multi-stage evolution and interconnected coupling features.Under time pressure,case-based reasoning(CBR)has emerged as a critical method for risk management decision making.Case-based reasoni...Urban disaster risks show multi-stage evolution and interconnected coupling features.Under time pressure,case-based reasoning(CBR)has emerged as a critical method for risk management decision making.Case-based reasoning tackles target case problems by leveraging solutions from similar historical cases.However,the current case base is inadequate for storing systemic risk cases,thus impeding CBR efficacy.This article presents a city-level integrated case base with a nested cross structure to facilitate the use of CBR in systemic risk management.It comprises a multi-layer vertical dimension and a multi-scale horizontal dimension.The vertical dimension is optimized to a four-layer(environment-hazard-object-aftermath)risk scenario classification system with taxonomy and fuzzy clustering analysis.The horizontal dimension is improved to a three-scale(network-chain-pair)risk association mode using event chain theory and association analysis.Hazard acts as the pivotal link between the two dimensions.An illustrative example displays the use process of the proposed case base,along with a discussion of its CBR-supported applications.Through the digital transformation,the suggested case base can serve government decision making with CBR,enhancing the city’s capability to reduce systemic risk.展开更多
基金Sponsored by the Fundamental Research Funds for the Central Universities (Grant No. HIT. NSRIF. 2010096)the Heilongjiang Post-Doctorial Fi-nancial Assistance (Grant No. LBH-Z09187)
文摘A kind of novel muhiband antenna with square-nested fractal is proposed and designed, including printed monopole antenna and dipole antenna, which are nested with a series of similar square elements. The antennas can synchronously operate in multiple frequencies, covering the four required frequencies, 2.4GHz/ 3.5GHz/5.2GHz/5.8GHz, for WLAN/WiMAX application. The antenna surface currents are simulated by CST MWS, a three-dimension full-wave electromagnetic simulator, and the multiband operating mechanism has been explained from analysis of the simulation results. Then the models of the two proposed antennas fed by coplanar waveguide （monopole antenna） and balanced microstripline （dipole antenna）, respectively, have been obtained. Finally, prototypes of the two antennas have been manufactured and measured in anechoic chamber. The results well match the simulation results, which verifies the feasibility of design idea. Moreover, these antennas are miniature and the design idea can be easily applied into other types of nested structure, the features of which make the Proposed antennas have promising application in muhiband fields.
基金supported by the National Natural Science Foundation of China(Grant No.32170485,31501867)the Fundamental Research Funds for the Central Universities(Grant No.2572022BE02)。
文摘Artificial nest boxes are placed to attract birds to nest and breed in a specific location,and they are widely used in avian ecology research and in the attraction of insectivorous birds.There is evidence that artificial nest boxes can adversely affect breeding fitness but no great focus has been placed on this issue by researchers.Therefore,we retrieved 321 research papers regarding artificial nest boxes published from 2003 to 2022 and used the'Biblioshiny'program to extract and integrate keywords;we then summarized the adverse effects of artificial nest boxes on avian breeding success.The studies highlighted many drawbacks and misuses in the designing and placement of nest boxes;furthermore,bird attraction was decreased by their inappropriate selection,thus reducing breeding success.Regarding nest box production,there were shortcomings in the construction material,color,smell,and structural design of the boxes used.Nest boxes were also placed at inappropriate densities,locations,orientations,heights,and managed incorrectly.Finally,we propose suggestions for more efficient and safer artificial nest boxes for future use in avian ecology research and bird conservation.
基金supported by the National Natural Science Foundation of China(Grant Nos.72274123,71904121,72004113,72404185)Science and Technology Commission of Shanghai Municipality(Grant Nos.24692104600,23692116200).
文摘Urban disaster risks show multi-stage evolution and interconnected coupling features.Under time pressure,case-based reasoning(CBR)has emerged as a critical method for risk management decision making.Case-based reasoning tackles target case problems by leveraging solutions from similar historical cases.However,the current case base is inadequate for storing systemic risk cases,thus impeding CBR efficacy.This article presents a city-level integrated case base with a nested cross structure to facilitate the use of CBR in systemic risk management.It comprises a multi-layer vertical dimension and a multi-scale horizontal dimension.The vertical dimension is optimized to a four-layer(environment-hazard-object-aftermath)risk scenario classification system with taxonomy and fuzzy clustering analysis.The horizontal dimension is improved to a three-scale(network-chain-pair)risk association mode using event chain theory and association analysis.Hazard acts as the pivotal link between the two dimensions.An illustrative example displays the use process of the proposed case base,along with a discussion of its CBR-supported applications.Through the digital transformation,the suggested case base can serve government decision making with CBR,enhancing the city’s capability to reduce systemic risk.
