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Single-point and Filtered Relative Position Estimation for Visual Docking

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Computer Modeling in Engineering & Sciences 2016年第2期111卷 147-169页

作者： Dylan Conway Daniele Mortari Aerospace Engineering Texas A&M UniversityCollege Station77843

This paper presents a new method to estimate position from line-ofsight measurements to known targets when attitude is *** algorithm has two *** first produces a closed-form unbiased estimate for position that does not account for the measurement error *** second stage is iterative and produces an estimate of position that explicitly accounts for the measurement error covariance and the coupling between measurement error and sensor-to-target *** algorithm gives an accurate estimate of both position and the corresponding position error covariance and has a low computational *** computational complexity is O(n)for n point-targets and only a 3×3 linear system must be *** algorithm is demonstrated for single-point position estimation to verify the accuracy of the resulting position and *** improvements over current methods are shown through statistical *** algorithm is then demonstrated in the context of sequential filtering for space vehicle docking.

关键词： Visual point algorithm

Construction and Optimization of TRNG Based Substitution Boxes for Block Encryption Algorithms

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Computers, Materials & Continua 2022年第11期73卷 2679-2696页

作者： Muhammad Fahad Khan Khalid Saleem Mohammed Alotaibi Mohammad Mazyad Hazzazi Eid Rehman Aaqif Afzaal Abbasi Muhammad Asif Gondal Quaid e Azam University Islamabad45320Pakistan Foundation University Islamabad Islamabad44000Pakistan College of Business administration University of TabukTabuk71491Saudi Arabia Department of Mathematics College of ScienceKing Khalid UniversityAbha61413Saudi Arabia Department of Mathematics and Sciences Dhofar UniversitySalalah211Oman

Internet of Things is an ecosystem of interconnected devices that are accessible through the *** recent research focuses on adding more smartness and intelligence to these edge *** makes them susceptible to various kinds of security *** edge devices rely on cryptographic techniques to encrypt the pre-processed data collected from the sensors deployed in the *** this regard,block cipher has been one of the most reliable options through which data security is *** strength of block encryption algorithms against different attacks is dependent on its nonlinear primitive which is called Substitution *** the design of S-boxes mainly algebraic and chaos-based techniques are used but researchers also found various weaknesses in these *** the other side,literature endorse the true random numbers for information security due to the reason that,true random numbers are purely *** this paper firstly a natural dynamical phenomenon is utilized for the generation of true random numbers based ***,a systematic literature review was conducted to know which metaheuristic optimization technique is highly adopted in the current decade for the optimization of *** on the outcome of Systematic Literature Review(SLR),genetic algorithm is chosen for the optimization of *** results of our method validate that the proposed dynamic S-boxes are effective for the block ***,our results showed that the proposed substitution boxes achieve better cryptographic strength as compared with state-of-the-art techniques.

关键词： IoT security sensors data encryption substitution box generation True Random Number Generators(TRNG) heuristic optimization genetic algorithm

Quantitative analysis of morphometry on Ribb and Gumara watersheds: Implications for soil and water conservation

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International Soil and Water Conservation Research 2019年第2期7卷 150-157页

作者： Daniel Asfaw Getachew Workineh Debre Tabor University Department of Geography and Environmental Studies Ethiopia Debre Tabor University Department of Geography and Environmental Studies Ethiopia

Morphometric analysis is a quantitative measurement and mathematical analysis of *** plays a significant role in understanding the geohydrological characteristics of a drainage basin in relation to the terrain feature and its flow *** also helps to estimate the incidence of infiltration and runoff,and other related hydrological character of a watershed like erosion and sediment transport which has a strong implication for natural resource *** study has attempted to quantify the morphometric characteristics of Guna-Tana watershed for proper implementation of soil and water conservation *** (DEM) was used for extracting morphometric *** watershed covers a total area of 3601.5 km2 and it has a basin length of 78.89 *** has been tried to generate morphometric parameters which account basin drainage network,geometry,drainage texture,and relief characteristics together with hypsometric *** morphometric analysis of drainage density of the study watershed is 0.49 km/km2 which indicates the basin is highly permeable and result with better underground water storage *** number is 0.02 that implies the area is less prone to soil *** addition,it has stream frequency of 0.32 and form factor 0.57 which indicates slightly elongated basin *** analysis of its sub watersheds Gumara and Ribb was also ***,practicing soil and water conservation in the watershed could enhance/strengthen the water storage capacity,prevent sediment loss and related natural resource from the watershed that rehabilitate its productivity.

关键词： Morphometric analysis Drainage density Guna-Tana watershed Soil and water conservation

Dynamic Responses of Atmospheric Carbon Dioxide Concentration to Global Temperature Changes between 1850 and 2010

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Advances in Atmospheric Sciences 2016年第2期33卷 247-258页

作者： Weile WANG Ramakrishna NEMANI Department of Science and Environmental Policy California State University at Monterey Bay Earth Science Division NASA Ames Research Center NASA Advanced Supercomputing Division NASA Ames Research Center

Changes in Earth＇s temperature have significant impacts on the global carbon cycle that vary at different time scales, yet to quantify such impacts with a simple scheme is traditionally deemed difficult. Here, we show that, by incorporating a tem- perature sensitivity parameter （1.64 ppm yr-1 ℃-1） into a simple linear carbon-cycle model, we can accurately characterize the dynamic responses of atmospheric carbon dioxide （CO2） concentration to anthropogenic carbon emissions and global temperature changes between 1850 and 2010 （r2 〉 0.96 and the root-mean-square error 〈 1 ppm for the period from 1960 onward）. Analytical analysis also indicates that the multiplication of the parameter with the response time of the atmospheric carbon reservoir （-12 year） approximates the long-term temperature sensitivity of global atmospheric CO2 concentration （-15 ppm ℃ 1）, generally consistent with previous estimates based on reconstructed CO2 and climate records over the Little Ice Age. Our results suggest that recent increases in global surface temperatures, which accelerate the release of carbon from the surface reservoirs into the atmosphere, have partially offset surface carbon uptakes enhanced by the elevated atmo- spheric CO2 concentration and slowed the net rate of atmospheric CO2 sequestration by global land and oceans by -30% since the 1960s. The linear modeling framework outlined in this paper thus provides a useful tool to diagnose the observed atmospheric CO2 dynamics and monitor their future changes.

关键词： atmospheric CO2 dynamics climate-carbon interactions climate change carbon cycle

The mathematical weighting of GNSS observations based on different types of receivers/antennas and environmental conditions

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Geodesy and Geodynamics 2023年第5期14卷 521-540页

作者： Kamal Parvazi Saeed Farzaneh Abdolreza Safari School of Surveying and Geospatial Engineering College of EngineeringUniversity of TehranNorth Kargar Street***TehranIran

Stochastic models play an important role in achieving high accuracy in positioning,the ideal estimator in the least-squares(LS)can be obtained only by using the suitable stochastic *** study investigates the role of variance component estimation(VCE)in the LS method for Precise Point Positioning(PPP).This estimation is performed by considering the ionospheric-free(IF)functional model for code and the phase observation of Global Positioning System(GPS).The strategy for estimating the accuracy of these observations was evaluated to check the effect of the stochastic model in four modes:a)antenna type,b)receiver type,c)the tropospheric effect,and d)the ionosphere *** results show that using empirical variance for code and phase observations in some cases caused erroneous estimation of unknown components in the PPP *** is because a constant empirical variance may not be suitable for various receivers and antennas under different *** were compared in two cases using the stochastic model of nominal weight and weight estimated by *** position error difference for the east-west,north-south,and height components was 1.5 cm,4 mm,and 1.8 cm,***,weight estimation with LS-VCE can provide more appropriate ***,the convergence time based on four elevation-dependent models was evaluated using nominal weight and LS-VCE *** to the results,the LS-VCE has a higher convergence rate than the nominal *** weight estimation using LS-VCE improves the convergence time in four elevation-dependent models by 11,13,12,and 9 min,respectively.

关键词： Stochastic model Global positioning system Variance component estimation Least-squares Precise point positioning Elevation-dependent model

Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars

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Research in Astronomy and Astrophysics 2019年第12期19卷 169-178页

作者： Bin Ma Zhaohui Shang Michael S.Brotherton national Astronomical Observatories Chinese Academy of Sciences.Beijing 100101China School of Astronomy and space Science University of Chinese Academy of SciencesBeijing 100049China Tianjin Astrophysics Center Tianjin Normal UniversityTianjin 300387China Department of Physics and Astronomy University of WyomingLaramieWY 82071.USA

Studying the relationships among quasar spectral features is essential to unveil the origins of the emission lines and the quasars’ physical processes. Principal component analysis(PCA) is a powerful tool to investigate correlations between variables. Here, we present the results of PCA on the spectra of low-redshift SDSS quasars. The rest-frame wavelength range studied is 4000 – 5500 ?, involving some typical features of quasar spectra, such as Hβ, [O Ⅲ] and Fe Ⅱ emission lines. The first principal component is the anti-correlation between [O Ⅲ] and Fe Ⅱ, the well-known eigenvector one(EV1). The next six principal components also show clear(anti-)correlations between line strengths and/or velocity widths of various features, which agree well with measured spectral properties. By comparing the weights of these principal components with other quasar properties, we can identify their underlying drivers. We find that the second principal component represents spectral slope, and can quantify quasar host fraction, intrinsic slope and reddening well. The third component exhibits the velocity width variation of Hβ, and may be a proxy for orientation. In addition, we calculate the fractional-contribution spectra to investigate which components dominate the variance at individual wavelength ranges. Our results also indicate that the optical Fe Ⅱ emission may have distinct origins.

关键词： quasars:emission lines quasars:general

Analyzing CO_(2) concentration changes and their influencing factors in Indonesia by OCO-2 and other multi-sensor remote-sensing data

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International Journal of Digital Earth 2018年第8期11卷 825-844页

作者： Shuai Yin Xiufeng Wang Heri Santoso Hiroshi Tani Guosheng Zhong Zhongyi Sun Graduate School of Agriculture Hokkaido UniversitySapporoJapan Research Faculty of Agriculture Hokkaido UniversitySapporoJapan c Indonesian Oil Palm Research Institute MedanNorth SumatraIndonesia

We used OCO-2 products and considered three factors that potentially affect CO_(2) concentration in Indonesia:sea surface temperature(SST),forest fires and *** 2014 to 2016,CO_(2) concentration in Indonesia showed a trend of increase,which is consistent with the global increase reported by the Greenhouse Gases Observing Satellite(GOSAT)*** an archipelago country,the results indicate that SST has a direct effect on the CO_(2) concentration in *** changing exhibits similar fluctuations;meanwhile,CO_(2) concentration and SST also presented positive *** 2015,the number of fire hotspots suddenly increased to 140,699,because of occurrence of the worst forest *** to special geographic conditions,forest fires did not induce CO_(2) concentration changes in Indonesia,but CO_(2) concentration in the corresponding islands showed a trend of ***_(2) concentration increased in Kalimantan during the occurrence of forest fire in September–October 2014,and CO_(2) concentration increased in Kalimantan and Sumatra during the occurrence of forest fire in September–October *** indices were stable and presented no correlation with CO_(2) *** study demonstrated that OCO-2 is capable of monitoring CO_(2) concentration at a regional scale;additionally,an effective method for using OCO-2 Level 2 products is proposed.

关键词： GOSAT Kalimantan SST Sumatra X_(CO_(2))

Country-scale spatio-temporal monitoring of soil erosion in Iran using the G2 model

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International Journal of Digital Earth 2021年第8期14卷 1019-1039页

作者： Shahin Mohammadi Fatemeh Balouei Khadijeh Haji Abdulvahed Khaledi Darvishan Christos G.Karydas Department of Remote Sensing and GIS Faculty of Earth SciencesShahid Chamran University of AhvazAhvazIran Department of Range and Watershed Management Faculty of Natural ResourcesIsfahan University of TechnologyIsfahanIran Department of Watershed Management Engineering Faculty of Natural ResourcesTarbiat Modares UniversityNoorIran dRemote Sensing Engineer EpanomiGreece

The aim of this study was the spatial and temporal monitoring of soil erosion patterns in *** G2 model was used,as an appropriate tool to provide the required month-time step country-wide soil loss maps and statistical *** input parameters were derived with field surveys and remote sensing imagery(MODIS,SRTM,SPOT,and Sentinel-2 scenes).An innovation for G2 was the consideration of the snow cover effect on the rainfall *** was also the first time G2 was used to map such a big country like Iran on a country *** mean annual soil erosion in Iran was found to be 16.5 t ha−1,which is equal to about 2.7 billion tons of soil *** spatial terms,the highest soil loss values were found in the north,west and southwest part of Iran,in the steep slopes in Alborz and Zagros *** temporal terms,the highest and lowest monthly erosion values of 3.2 and 0.09 t ha−1 correspond to January and July,respectively.

关键词： Digital earth Land degradation Sediment yield Sentinel-2 Snow cover effect

A review on the development of electrolytes for lithiumbased batteries for low temperature applications

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Frontiers in Energy 2023年第1期17卷 43-71页

作者： Jason A.MENNEL Dev CHIDAMBARAM Department of Chemical and Materials Engineering University of Nevada−RenoRenoNV 89557USA Department of Chemical and Materials Engineering Nevada Institute for Sustainability University of Nevada−RenoRenoNV 89557USA

The aerospace industry relies heavily on lithium-ion batteries in instrumentation such as satellites and land *** equipment is exposed to extremely low temperatures in space or on the Martian *** extremely low temperatures affect the discharge characteristics of the battery and decrease its available working *** solvents,cosolvents,additives,and salts have been researched to fine tune the conductivity,solvation,and solid-electrolyte interface forming properties of the *** different resistive phenomena have been investigated to precisely determine the most limiting steps during charge and discharge at low *** mission lifespans as well as self-reliance on the chemistry are now highly desirable to allow low temperature performance rather than rely on external heating *** Martian rovers are equipped with greater instrumentation and demands for greater energy storage rise,new materials also need to be adopted involving next generation lithiumion chemistry to increase available *** these objectives in mind,tailoring of the electrolyte with highercapacity materials such as lithium metal and silicon anodes at low temperatures is of high *** review paper highlights the progression of electrolyte research for low temperature performance of lithium-ion batteries over the previous several decades.

关键词： electrolyte lithium-ion low temperature aerospace solid-electrolyte interface