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Information flow and controlling in regularization inversion of quantitative remote sensing

Science China Earth Sciences 2005年第1期48卷 74-83页

作者： YANG Hua, XU Wangli, ZHAO Hongrui, CHEN Xue & WANG Jindi research center for Remote sensing and GIS, School of Geography, Beijing Normal University, State Key Laboratory of Remote sensing Science, Beijing Key Laboratory for Remote sensing of Environment and Digital Cities, Beijing 100875, China Department of Mathematics, Beijing Normal University, Beijing 100875, China 1. research center for Remote sensing and GIS School of Geography Beijing Normal University State Key Laboratory of Remote Sensing Science Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities 100875 Beijing China 2. Department of Mathematics Beijing Normal University 100875 Beijing China

In order to minimize uncertainty of the inversed parameters to the largest extent by making full use of the limited information in remote sensing data, it is necessary to understand what the information flow in quantitative remote sensing model inversion is, thus control the information flow. Aiming at this, the paper takes the linear kernel-driven model inversion as an example. At first, the information flow in different inversion methods is calculated and analyzed, then the effect of information flow controlled by multi-stage inversion strategy is studied, finally, an information matrix based on USM is defined to control information flow in inversion. It shows that using Shannon entropy decrease of the inversed parameters can express information flow more properly. Changing the weight of a priori knowledge in inversion or fixing parameters and partitioning datasets in multi-stage inversion strategy can control information flow. In regularization inversion of remote sensing, information matrix based on USM may be a better tool for quantitatively controlling information flow.

关键词： regularization inversion, information flow, Shannon entropy decrease, information matrix.

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Analyzing distributions for travel time data collected using radiofrequency identification technique in urban road networks

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Science China(Technological Sciences) 2019年第1期62卷 106-120页

作者： GUO JianHua LI ChangGuang QIN Xiao HUANG Wei WEI Yun CAO JinDe Intelligent Transportation System research center Southeast University Transportation sensing and Cognition research center Southeast University Department of Civil & Environmental Engineering University of Wisconsin at Milwaukee National Engineering Laboratory for Green and Safe Construction Technology in Urban Rail Transit School of Mathematics Southeast University

Travel time distribution studies are fundamental for supporting transportation system reliability studies, particularly for urban road networks. However, such studies are generally based on travel time data sets with limited sample sizes, which provide inconsistent findings. In this paper, a large amount of travel time data collected from the emerging radio frequency identification(RFID) technique are used to conduct empirical investigations and estimations of travel time distributions, and three major findings are determined. First, travel time data are shown to have a complex statistical structure: the travel time distribution is in general peaky, multi-modal, and skewed to the right, which cross validates findings shown in previous publications. Second, unimodal distribution models are shown to be unable to capture the complex statistical dynamics embedded in the travel time data; therefore,a multistate distribution model is more appropriate for modeling travel time distributions. In this respect, a three-component gaussian mixture model(GMM) is tested and results consistently outperform those of unimodal distribution models. Finally, the aggregation time interval is shown to have a trivial effect on the shape of travel time distributions: the travel time distribution is stable under different aggregation time intervals. Future work is recommended to investigate further travel time variabilities and travel time distribution estimations.

关键词： reliability travel time travel time distribution time interval RFID

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Improving the initialization speed for long-range NRTK in network solution mode

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Science China(Technological Sciences) 2020年第5期63卷 866-873页

作者： ZHANG Ming LÜJinHu BAI ZhengDong LIU Hui FAN ChengCheng Key Laboratory of systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Institute of Geomatics Tsinghua UniversityBeijing 100084China GNSS research center Wuhan UniversityWuhan 430079China Guangxi Zhuang Autonomous Region Remote sensing Information Surveying and Mapping Institute Nanning 530023China

Initialization speed is one of the most important factors in network real time kinematic(NRTK)*** to the low correlation among the error sources of reference stations,it is difficult to fix reference station ambiguities of long-range NRTK *** traditional reference stations ambiguity resolution(AR)methods,baselines are usually solved independently which is called baseline solution(BS)mode in this *** the correlations among baselines are not taken into consideration in ambiguities estimation,the AR speed is ***,tens of minutes or longer time is required to *** propose a network solution(NS)mode approach,in which the correlations among the double-difference ambiguities(DDAs)as well as double-difference ionospheric delays(DDIDs)of different baselines are considered in estimating float ambiguity *** results show that the float ambiguity solutions obtained are more accurate with an improved ***,initialization speed is significantly increased by 18%in NS mode.

关键词： initialization speed network real time kinematic(NRTK) reference station ambiguity resolution(AR) network solution(NS)mode baseline solution(BS)mode

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Defect engineering for advanced electrocatalytic conversion of nitrogen-containing molecules

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Science China Chemistry 2023年第4期66卷 1052-1072页

作者： Dongdong Wang Chen Chen Shuangyin Wang State Key Laboratory of Chemo/Bio-sensing and Chemometrics College of Chemistry and Chemical EngineeringAdvanced Catalytic Engineering Research Center of the Ministry of EducationHunan UniversityChangsha 410082China

Electrocatalytic conversion of nitrogen-containing molecules into valuable chemicals is a promising strategy to alleviate anthropogenic imbalances in the global nitrogen cycle,but developing efficient electrocatalysts remains a formidable *** recent years,the exploration of high-performance electrocatalysts has achieved significant progress by resorting to defect engineering strategy,which encouraged the researchers to understand the relationship between defects in catalysts and electrocatalytic *** this review,recent advances in defect engineering for advanced electrocatalytic conversion of nitrogen-containing molecules are systematically summarized,with special focus on electrocatalytic nitrogen oxidation and reduction,electrocatalytic nitric oxide oxidation and reduction,electrocatalytic nitrate reduction,and the construction of C–N *** can effectively tune the electronic structure of catalysts,facilitate species diffusion,and provide more adsorption/active sites for reaction intermediates,thereby enhancing the electrocatalytic ***,objective issues and future trends for optimizing electrocatalyst by defect engineering are proposed,which will contribute to the further development of advanced electrocatalytic conversion of nitrogen-containing molecules.

关键词： defect engineering electrocatalysis nitrogen-containing molecules C-N bond electrosynthesis

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Liquid Metal-Based Self-Healable and Elastic Conductive Fiber in Complex Operating Conditions

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Energy & Environmental Materials 2023年第6期6卷 297-304页

作者： Yin Zhou Yingying Zhu Zuan Hu Xiaoying Yang Pengkun Yang Lu Huang Yingpeng Wu State Key Laboratory of Chem/Bio-sensing and Chemometrics Advanced Catalytic Engineering Research Center of the Ministry of EducationCollege of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China

Flexible conductive fibers are essential for wearable electronics and smart electronic ***,in complex operating conditions,conductive fibers will inevitably fracture or ***,we have developed an elastic conductive self-healable fiber(C-SHF),of which the electrical and mechanical properties can efficiently heal in a wide operating range,including room temperature,underwater,and low *** advantage can be owed to the combination of reversible covalent imine bond and disulfide bond,as well as the instantaneous self-healing ability of liquid *** C-SHF,with stretchability,conductivity stability,and universal self-healing properties,can be used as an electrical signal transmission line at high strain and under different operating ***,C-SHF was assembled into a double-layer capacitor structure to construct a self-healable sensor,which can effectively respond to pressure as a wearable motion detector.

关键词： complex operating conditions elastic conductive fiber liquid metal self-healing

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Preparation and Properties of Fiber Optic Oxygen sensing Material by Thermo-polymerization Method

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 225-229页

作者： ZHANG Tianhua CHEN Xing HUANG Jun Hospital Wuhan University of Technology Wuhan 430070 China Fiber Optic sensing Technology research center Wuhan University of Technology Wuhan 430070 China

A new kind of fiber optic oxygen sensing material based on the fluorescence quenching of Ru（bpy）3Cl2 was prepared by the themo-polymerization method. The ruthenium dye was immobilized in N, N-methylene bisacrylamide（MBBA） polymer by physically trapping while MBBA was covalently crosslinked on the glass micro-beads by NaHSO3-O2-MnSO4 initiator system. The lock-in amplifyication technology was used for the detection of their sensing properties. The influences of indicator concentration, glass micro-beads diameter, post polymerization time, concentration and reaction time of glutaraldehyde on the properties of sensing materials were studied. To optimize the influencing factors to the sensing materials, the indicator concentration of 0.7 g/L, glass micro-beads diameter of 0.3 mm, post polymerization time of 5 h were achieved. The immobilization stability of ruthenium dye and the performance of the sensing materials were improved by the new polymerization system. An absolute detection limit of 3×10-6 （V/V） and the response time of 10 s were obtained. This kind of sensing materials has good stability and their life time is 2 years.

关键词： thermo-polymerization fiber optic sensing materials stability

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Application of wavelet support vector regression on SAR data de-noising

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Journal of systems Engineering and Electronics 2011年第4期22卷 579-586页

作者： Yi Lin Shaoming Zhang Jianqing Cai Nico Sneeuw research center of Remote sensing and Spatial Technology Tongji University Shanghai 200092 P. R. China Institute of Geodesy University of Stuttgart D-70174 Stuttgart Germany

A new filtering method for SAR data de-noising using wavelet support vector regression （WSVR） is developed. On the basis of the grey scale distribution character of SAR imagery, the logarithmic SAR image as a noise polluted signal is taken and the noise model assumption in logarithmic domain with Gaussian noise and impact noise is proposed. Based on the better per- formance of support vector regression （SVR） for complex signal approximation and the wavelet for signal detail expression, the wavelet kernel function is chosen as support vector kernel func- tion. Then the logarithmic SAR image is regressed with WSVR. Furthermore the regression distance is used as a judgment index of the noise type. According to the judgment of noise type every pixel can be adaptively de-noised with different filters. Through an approximation experiment for a one-dimensional complex signal, the feasibility of SAR data regression based on WSVR is con- firmed. Afterward the SAR image is treated as a two-dimensional continuous signal and filtered by an SVR with wavelet kernel function. The results show that the method proposed here reduces the radar speckle noise effectively while maintaining edge features and details well.

关键词： synthetic aperture radar (SAR) support vector regres-sion (SVR) kernel function wavelet analysis function approximation.

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Charge qubits based on ultra-thin topological insulator films

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Frontiers of physics 2024年第3期19卷 71-81页

作者： Kexin Zhang Hugo V.Lepage Ying Dong Crispin H.W.Barnes research center for Quantum sensing Intelligent Perception Research InstituteZhejiang LabHangzhou 311121China Cavendish Laboratory Department of PhysicsUniversity of CambridgeCambridge CB30HEUnited Kingdom

We study how to use the surface states in a Bi2Se3 topological insulator ultra-thin film that are affected by finite size effects for the purpose of quantum *** demonstrate that:(i)surface states under the finite size effect can effectively form a two-level system where their energy levels lie in between the bulk energy gap and a logic qubit can be constructed,(ii)the qubit can be initialized and manipulated using electric pulses of simple forms,(iii)two-qubit entanglement is achieved through a√SWAP operation when the two qubits are in a parallel setup,and(iv)alternatively,a Floquet state can be exploited to construct a qubit and two Floquet qubits can be entangled through a Controlled-NOT *** Floquet qubit offers robustness to background noise since there is always an oscillating electric field applied,and the single qubit operations are controlled by amplitude modulation of the oscillating field,which is convenient experimentally.

关键词： topological insulator quantum computing nanodevices

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Chlorophyll Fluorescence Detected Passively by Difference Reflectance Spectra of Wheat （Triticum aestivum L.） Leaf

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Journal of Integrative Plant Biology 2005年第10期47卷 1228-1235页

作者： Yong-Jiang ZHANG Chun-Jiang ZHAO Liang-Yun LIU Ji-Hua WANG Ren-Chao WANG Institute of Agricultural Remote sensing and Information Application Zhejiang University Hangzhou 310029 China National Engineering research center for Information Technology in Agriculture Beijing 100089 China

The chlorophyll fluorescence （CF） signature emitted from vegetation provides an abundance of information regarding photosynthetics activity and has been used as a powerful tool to obtain physiological information of plant leaves in a non-invasive manner. CF is difficult to quantify because the CF signal is obscured by reflected light. In the present study, the apparent reflectance spectra of wheat （Triticum aestivum L.） leaves were measured under illuminations with and without filtering by three specially designed long-wave pass edge filters; the cut-off wavelengths of the three filters were 653.8, 678.2, and 694. l nm at 50% of maximum transmittance. The CF spectra could be derived as the reflectance difference spectra of the leaves under illuminations with and without the long wave pass edge filters. The ratio of the reflectance difference at 685 and 740 nm （Dif685/Dif740） was linear correlated with the CF parameters （maximal photochemical efficiency Fv/Fm, and the yield of quantum efficiency） measured by the modulated fluorometer. In addition, the ratio reflected the water stress status of the wheat leaf, which was very high when water deficiency was serious. This method provides a new approach for detecting CF and the physiological state of crops.

关键词： chlorophyll fluorescence (CF) passive remote sensing reflectance spectrum wheat.

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Sustainable earth observations for the Arctic,the Antarctic and the high-altitude mountain cold regions

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International Journal of Digital Earth 2019年第8期12卷 858-859页

作者： Jouni Pulliainen Bin Cheng Yubao Qiu Arctic research center Finnish Meteorological Institute Finnish Meteorological Institute Institute of Remote sensing and Digital Earth Chinese Academic of Science

The Arctic,the Antarctic as well as the Qinghai-Tibet Plateau(QTP)are cold regions on Earth where snow and ice dominate the local environment and impact the global climate via several strong feedback *** observations and information service for those cold regions are vital for the societal benefits,and support from the science to policy making(Qiu et al.2016).Earth cold regions exhibit strong sensitivity to global climate change and are thus some of the most fragile regions in terms of global ecology(Pulliainen et al.2017).Due to these inherent similarities,the Qinghai-Tibet Plateau area has been termed as the‘Third Pole’,which is experiencing profound environmental changes.

关键词： Arctic Antarctic Earth

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