The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimat...The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimation for SINS on a rocking base is presented in this paper.The algorithm transforms the initial alignment into the initial attitude determination problem by using infinite vector observations to remove the angular motions,the SINS alignment is heuristically established as an optimiza-tion problem of finding the minimum eigenvector.In order to further improve the alignment precision,an adaptive recursive weighted least squares(ARWLS)curve fitting algorithm is used to fit the translational motion interference-contaminated reference vectors according to their time domain characteristics.Simulation studies and experimental results favorably demonstrate its rapidness,accuracy and robustness.展开更多
Shallow conductive heterogeneity can lead to static shifts ain the apparent resistivity sounding curve of controlled-source audio-frequency magnetotellurics(CSAMT).The static effect will shift the apparent resistivity...Shallow conductive heterogeneity can lead to static shifts ain the apparent resistivity sounding curve of controlled-source audio-frequency magnetotellurics(CSAMT).The static effect will shift the apparent resistivity curves along with axial log-log coordinates.Such an effect,if not properly processed,can distort the resistivity of rock formation and the depth of interfaces,and even make the geological structures unrecognizable.In this paper,we discuss the reasons and characteristics of the static shift and summarize the previous studies regarding static shift correction.Then,we propose the Guided Image Filtering algorithm to suppress static shifts in CSAMT.In detail,we use the multi-window superposition method to superimpose 1D signals into a 2D matrix image,which is subsequently processed with Guided Image Filtering.In the synthetic model study and field examples,the Guided Image Filtering algorithm has effectively corrected and suppressed static shifts,and finally improved the precision of data interpretation.展开更多
针对SS304不锈钢水槽件在拉深过程中出现的零件起皱问题,采用正交试验方法研究凹模圆角半径、压边力和摩擦因数对起皱问题的影响。通过有限元分析软件Dynaform对正交试验方案进行仿真验证,考察了最大增厚率和凹模圆角半径、压边力和摩...针对SS304不锈钢水槽件在拉深过程中出现的零件起皱问题,采用正交试验方法研究凹模圆角半径、压边力和摩擦因数对起皱问题的影响。通过有限元分析软件Dynaform对正交试验方案进行仿真验证,考察了最大增厚率和凹模圆角半径、压边力和摩擦因数等3个成型影响因素之间的关系。试验结果表明,该SS304不锈钢盒型件的最佳成型工艺组合为R1C4F4,即:凹模圆角半径为5 m m,摩擦因数为0.2和压边力为50 kN。依据优化结果,改进了模具结构设计,从而较好地解决了SS304不锈钢盒型件的成型问题。展开更多
社会与情感能力是人生成功和幸福的奠基石。2021年SSES(Study on Social and Emotion-al Skills)全球首测结果发布,为开展青少年社会与情感能力的国际比较研究提供了坚实的数据基础。本文运用DEA(Data Envelope Analysis)方法,将班级规...社会与情感能力是人生成功和幸福的奠基石。2021年SSES(Study on Social and Emotion-al Skills)全球首测结果发布,为开展青少年社会与情感能力的国际比较研究提供了坚实的数据基础。本文运用DEA(Data Envelope Analysis)方法,将班级规模、教师学历、SSES培训、SSES措施、校园活动作为投入变量,将五大能力作为产出变量,对参加本次国际测评的10座城市的1171所中小学进行培养成效评估,结果发现:(1)各城市中小学的社会与情感能力培养成效普遍较高,小学阶段的均值在0.8以上,中学阶段的均值在0.9以上;(2)在小学阶段,苏州学校的培养成效较为突出,不仅均值最高,而且整体属于高水平均衡型;在中学阶段,培养成效较为突出的城市则是伊斯坦布尔,属于高水平均衡型;(3)各城市共有82所高绩效小学和87所高绩效中学,其中伊斯坦布尔和波哥大的占比较大;(4)学校归属感对各城市中小学的社会与情感能力培养成效提升具有重要促进作用。根据以上研究结果,本文建议应该加强社会与情感能力的国际合作与实证研究,在总结苏州成功经验的同时寻找差距补齐短板,将优质均衡作为我国中小学社会与情感能力培养工作的重要目标。展开更多
To suppress the interference in the ultra-wideband （AI-UWB） system is a challenging problem. An anti-interference multiband orthogonal frequency-division multiplexing ultra-wideband （AI-UWB） system, based on sprea...To suppress the interference in the ultra-wideband （AI-UWB） system is a challenging problem. An anti-interference multiband orthogonal frequency-division multiplexing ultra-wideband （AI-UWB） system, based on spreading and interleaving is addressed. It will exploit the frequency diversity across the subcarriers and provide the robustness to narrow-band interference, by spreading the coded bit streams within each sub-band and interleaving across all sub-bands. Simulating results show that the spreading and interleaving provide about 5 dB to 10 dB advantages over the conventional multiband orthogonal frequency-division multiplexing ultra-wideband system in signal-to-interference ratio. Spreading and interleaving is an effective cure for enhancing the robustness to narrowband interference.展开更多
基金supported by the National Natural Science Foundation of China(41174162).
文摘The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimation for SINS on a rocking base is presented in this paper.The algorithm transforms the initial alignment into the initial attitude determination problem by using infinite vector observations to remove the angular motions,the SINS alignment is heuristically established as an optimiza-tion problem of finding the minimum eigenvector.In order to further improve the alignment precision,an adaptive recursive weighted least squares(ARWLS)curve fitting algorithm is used to fit the translational motion interference-contaminated reference vectors according to their time domain characteristics.Simulation studies and experimental results favorably demonstrate its rapidness,accuracy and robustness.
基金sponsored by the Basic Science Center Project of National Natural Science Foundation of China(72088101)。
文摘Shallow conductive heterogeneity can lead to static shifts ain the apparent resistivity sounding curve of controlled-source audio-frequency magnetotellurics(CSAMT).The static effect will shift the apparent resistivity curves along with axial log-log coordinates.Such an effect,if not properly processed,can distort the resistivity of rock formation and the depth of interfaces,and even make the geological structures unrecognizable.In this paper,we discuss the reasons and characteristics of the static shift and summarize the previous studies regarding static shift correction.Then,we propose the Guided Image Filtering algorithm to suppress static shifts in CSAMT.In detail,we use the multi-window superposition method to superimpose 1D signals into a 2D matrix image,which is subsequently processed with Guided Image Filtering.In the synthetic model study and field examples,the Guided Image Filtering algorithm has effectively corrected and suppressed static shifts,and finally improved the precision of data interpretation.
文摘针对SS304不锈钢水槽件在拉深过程中出现的零件起皱问题,采用正交试验方法研究凹模圆角半径、压边力和摩擦因数对起皱问题的影响。通过有限元分析软件Dynaform对正交试验方案进行仿真验证,考察了最大增厚率和凹模圆角半径、压边力和摩擦因数等3个成型影响因素之间的关系。试验结果表明,该SS304不锈钢盒型件的最佳成型工艺组合为R1C4F4,即:凹模圆角半径为5 m m,摩擦因数为0.2和压边力为50 kN。依据优化结果,改进了模具结构设计,从而较好地解决了SS304不锈钢盒型件的成型问题。
文摘社会与情感能力是人生成功和幸福的奠基石。2021年SSES(Study on Social and Emotion-al Skills)全球首测结果发布,为开展青少年社会与情感能力的国际比较研究提供了坚实的数据基础。本文运用DEA(Data Envelope Analysis)方法,将班级规模、教师学历、SSES培训、SSES措施、校园活动作为投入变量,将五大能力作为产出变量,对参加本次国际测评的10座城市的1171所中小学进行培养成效评估,结果发现:(1)各城市中小学的社会与情感能力培养成效普遍较高,小学阶段的均值在0.8以上,中学阶段的均值在0.9以上;(2)在小学阶段,苏州学校的培养成效较为突出,不仅均值最高,而且整体属于高水平均衡型;在中学阶段,培养成效较为突出的城市则是伊斯坦布尔,属于高水平均衡型;(3)各城市共有82所高绩效小学和87所高绩效中学,其中伊斯坦布尔和波哥大的占比较大;(4)学校归属感对各城市中小学的社会与情感能力培养成效提升具有重要促进作用。根据以上研究结果,本文建议应该加强社会与情感能力的国际合作与实证研究,在总结苏州成功经验的同时寻找差距补齐短板,将优质均衡作为我国中小学社会与情感能力培养工作的重要目标。
基金the National "863" High Technology Research Program of China (2005AA123320)Universities Natural Science Research Project of Jiangsu Province (05KJB510101).
文摘To suppress the interference in the ultra-wideband （AI-UWB） system is a challenging problem. An anti-interference multiband orthogonal frequency-division multiplexing ultra-wideband （AI-UWB） system, based on spreading and interleaving is addressed. It will exploit the frequency diversity across the subcarriers and provide the robustness to narrow-band interference, by spreading the coded bit streams within each sub-band and interleaving across all sub-bands. Simulating results show that the spreading and interleaving provide about 5 dB to 10 dB advantages over the conventional multiband orthogonal frequency-division multiplexing ultra-wideband system in signal-to-interference ratio. Spreading and interleaving is an effective cure for enhancing the robustness to narrowband interference.
