Multi-Scale Fusion Algorithm for AUVs Integrated Navigation Systems

To deal with the low location accuracy issue of existing underwater navigation technologies in autonomous underwater vehicles(AUVs),a distributed fusion algorithm which combines the model's analysis method with a multi-scale transformation method is proposed for integrated navigation system based on AUV.First,integrated navigation system theory and system error sources are introduced in details.Secondly,a navigation system's observation equation on the original scale is decomposed into different scales by the discrete wavelet transform method,and noise reduction is performed by setting the wavelet de-noising threshold.At last,the dynamic equation and observation equations are fused on different scales by the wavelet transformation and Kalman filter.The results show that the proposed algorithm has smaller navigation error and higher navigation accuracy.

潜艇航渡阶段隐身辅助决策系统研究

Stealth security has always been considered as an important guarantee for the vitality and combat effectiveness of submarines.In accordance with the stealth requirements of submarines performing stealth voyage tasks,this paper proposes a stealth assistant decision system.Firstly,the submarine stealth posture is acquired.A fuzzy neural network inference engine based on improved simplified particle swarm optimization is designed.The auxiliary decision-making scheme for state control and maneuver avoidance of submarine and its equipment is automatically generated.Secondly,the simulation and deduction of the assistant decision-making scheme are realized by the calculation modules of sound source level,propagation loss,and stealth situation.The assistant decision-making scheme and simulation result provide decision support for the commander.Thirdly,the simulation experiment platform of the submarine stealth assistant decision system is constructed.The submarine stealth assistant decision system described in this paper can quickly and efficiently produce assistant decision-making schemes,including submarine and equipment control and maneuver avoidance.The scheme is in line with the combat experience and the results of the pre-model simulation experiments,whereas the simulation deduction evaluates the rationality and effectiveness of the selected scheme.The submarine stealth assistant decision system can adapt to a complex battlefield environment in addition to rapidly and accurately providing assistance in decision-making.

Functional traits of tree species with phylogenetic signal co-vary with environmental niches in two large forest dynamics plots

Aims While using phylogenetic and functional approaches to test the mechanisms of community assembly,functional traits often act as the proxy of niches.However,there is little detailed knowledge regarding the correlation between functional traits of tree species and their niches in local communities.We suggest that the co-varying correlation between functional traits and niches should be the premise for using phylogenetic and functional approaches to test mechanisms of community assembly.Using functional traits,phylogenetic and environmental data,this study aims to answer the questions:(i)within local communities,do functional traits of co-occurring species covary with their environmental niches at the species level?and(ii)what is the key ecological process underlying community assembly in Xishuangbanna and Ailaoshan forest dynamic plots(FDPs)?Methods We measured seven functional traits of 229 and 36 common species in Xishuangbanna and Ailaoshan FDPs in tropical and subtropical China,respectively.We also quantified the environmental niches for these species based on conditional probability.We then analyzed the correlations between functional traits and environmental niches using phylogenetic independent contrasts.After examining phylogenetic signals of functional traits using Pagel’sλ,we quantified the phylogenetic and functional dispersion along environmental gradients within local tree communities.Important Findings For target species,functional traits do co-vary with environmental niches at the species level in both of the FDPs,supporting that functional traits can be used as a proxy for local-scale environmental niches.Functional traits show significant phylogenetic signals in both of the FDPs.We found that the phylogenetic and functional dispersion were significantly clustered along topographical gradients in the Ailaoshan FDP but overdispersion in the Xishuangbanna FDP.These patterns of phylogenetic and functional dispersion suggest that environmental filtering plays a key role in structuring local tree assemblages in Ailaoshan FDP,while competition exclusion plays a key role in Xishuangbanna FDP.

Contrasting effects of space and environment on functional and phylogenetic dissimilarity in a tropical forest

Aims The evolutionary history and functional traits of species can illumi-nate ecological processes supporting coexistence in diverse forest communities.However,little has been done in decoupling the rela-tive importance of these mechanisms on the turnover of phylogenetic and functional characteristics across life stages and spatial scales.Therefore,this study aims to estimate the contribution of environment and dispersal on the turnover of phylogenetic and functional diversity across life stages and spatial scales,in order to build a coherent pic-ture of the processes responsible for species coexistence.Methods We conducted the study in Xishuangbanna Forest Dynamics Plot in Yunnan Province,southwest China.We used four different spatial point process models to estimate the relative importance of disper-sal limitation and environmental filtering.The functional traits and phylogenetic relationships of all individual trees were incorporated in the analyses to generate measures of dissimilarity in terms of pair-wise and nearest-neighbor phylogenetic and functional characteris-tics across life stages and spatial scales.Important Findings We found non-random patterns of phylogenetic and functional turnover across life stages and spatial scales.Environmental filtering structured pairwise phylogenetic and functional beta diversity across spatial scales,while dispersal limitation alone,and in combination with environment filtering,shaped nearest neighbor phylogenetic and functional beta diversity.The relative importance of dispersal limitation and environmental filtering appeared to change with life stage but not with spatial scale.Our findings suggest that phylogenetic and functional beta diversity help to reveal the ecological processes responsible for evolu-tionary and functional assembly and highlight the importance of using a range of different metrics to gain full insights into these processes.

Interior-stress fields produced by a general axisymmetric punch

This work is a supplement to the work of Sneddon on axisymmetric Boussinesq problem in 1965 in which the distributions of interior-stress fields are derived here for a punch with general profile.A novel set of mathematical procedures is introduced to process the basic elastic solutions(obtained by the method of Hankel transform,which was pioneered by Sneddon)and the solution of the dual integral equations.These processes then enable us to not only derive the general relationship of indentation depth D and total load P that acts on the punch but also explicitly obtain the general analytical expressions of the stress fields beneath the surface of an isotropic elastic half-space.The usually known cases of punch profiles are reconsidered according to the general formulas derived in this study,and the deduced results are verified by comparing them with the classical results.Finally,these general formulas are also applied to evaluate the von Mises stresses for several new punch profiles.

本征可修复的导电聚合物/水凝胶纳米复合薄膜及其独特的体沟道用于实现高性能、柔性和可修复的有机光电晶体管

柔性有机光电晶体管(OPTs)在大机械形变的下一代可穿戴系统中至关重要.然而,目前报道的大多数OPTs都是场效应基结构,其界面电荷传输和本征低跨导的特性限制了OPTs的机械柔性和光电性能的发展.此外,沟道层的p共轭半导体聚合物也缺乏特殊的可修复位点,使其很难实现薄膜的自我修复功能.本文报道了一个具有独特体沟道和强修复功能的柔性高光电性能的OPTs.该OPTs使用有机电化学晶体管架构,由3D体沟道的可修复导电聚合物/水凝胶复合薄膜组成.该器件不仅在遭受损伤后能够在100 ms内有效恢复其机械和电学性能,同时还展现出出色的机械柔性.更重要的是,该器件实现了紫外光波段的高光测性能,其中光响应度高达1.01×10^(5)A W^(-1),探测率达1.01×10^(5)A W^(-1),外量子效率达3.03×104%.结果表明,具有独特体沟道和本征可修复功能的OPTs在下一代可穿戴电子器件的使用中具有潜在应用价值.