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Assessment of widely used methods to derive depositional ages from detrital zircon populations

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Geoscience Frontiers 2019年第4期10卷 1421-1435页

作者： Daniel S.Coutts William a.matthews Stephen M.Hubbard Department of Geoscience University of Calgary

The calculation of a maximum depositional age(MDA)from a detrital zircon sample can provide insight into a variety of geological ***,the impact of sample size and calculation method on the accuracy of a resulting MDA has not been *** use large populations of synthetic zircon dates(N≈25,000)to analyze the impact of varying sample size(n),measurement uncertainty,and the abundance of neardepositional-age zircons on the accuracy and uncertainty of 9 commonly used MDA calculation ***,a new method,the youngest statistical population is *** each method,500 samples of n synthetic dates were drawn from the parent population and MDAs were *** mean and standard deviation of each method ove r the 500 trials at each n-value(50-1000,in increments of 50)were compa red to the known depositional age of the synthetic population and used to compare the methods quantitatively in two simulation *** first simulation scenario varied the proportion of near-depositional-age grains in the synthetic *** second scenario varied the uncertainty of the dates used to calculate the *** sample size initially decreased the mean residual error and standard deviation calculated by each *** higher n-values(>~300 grains),calculated MDAs changed more slowly and the mean resid ual error increased or decreased depending on the method *** the p roportion of near-depositional-age grains and lowering measurement uncertainty decreased the number of measurements required for the calculated MDAs to stabilize and decreased the standard deviation in calculated MDAs of the 500 *** of the two simulation scenarios show that the most successful way to increase the accuracy of a calculated M DA is by acquiring a large number of low-uncertainty measurements(300300)approach is used if the calculation of accurate MDAs are key to research *** acquisition method s,such as high-to moderate-precision m

关键词： Detrital zircon Maximum depositional age Geochronology Basin chronology LA-ICP-MS

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光纤陀螺在惯性测量装置中的应用

传感器技术 1993年第5期12卷 1-8页

作者： a.matthews 金正升 Litton Systems.Inc. Woodland HillsCalifornia

光纤陀螺技术发展迅速,估计在下一代先进的惯性测量装置中要使用它。概述了光纤陀螺的工作原理,并简要介绍了光纤陀螺用于试飞的情况,讨论了闭环干涉型光纤陀螺的工作过程。最后,对光纤陀螺的有关特点进行了讨论。

关键词：光纤陀螺惯性测量装置陀螺仪表

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光纤陀螺/硅加速度计惯性测量装置试验结果

国外导弹与航天运载器 1991年第10期 43-56页

作者： a.matthews 殷正和

根据天基反导弹合同(SDI 合同),采用光纤陀螺和小型微细加工的单晶硅加速度计两种新技术研制出一种轻重量的小型惯性测量装置(IMU)。本文介绍了这两种新型惯性仪表的工作原理。这两种仪表使 IMU 具有高灵敏度、宽频带、低噪声、轻重量... 详细信息

根据天基反导弹合同(SDI 合同),采用光纤陀螺和小型微细加工的单晶硅加速度计两种新技术研制出一种轻重量的小型惯性测量装置(IMU)。本文介绍了这两种新型惯性仪表的工作原理。这两种仪表使 IMU 具有高灵敏度、宽频带、低噪声、轻重量和快速反应等特点,适合于 SDI、军用和商业等多方面的应用。采用三个微型光纤陀螺(FOG)和三个硅加速度计组成的一个可供飞行的 IMU试验模型已经研制成功。这个试验模型在实验室内进行了静态和动态试验,试验数据较好地满足了性能要求。本文预测了下阶段的工作:进一步小型化,并将其推广到导弹和飞机的罗盘/姿态与航向基准系统(AHRS)等多方面的应用。

关键词：光学陀螺加速度计惯性测量装置

Experimental and analytical investigation on friction resistance force between buried coated pressurized steel pipes and soil

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 615-629页

作者： Shaurav ALAM Tanvir MANZUR John matthews Chris BARTLETT Erez ALLOUCHE Brent KEIL John KRAFT Department of Civil Engineering and Construction Engineering Technology Louisiana Tech UniversityRustonLA 71270USA Department of Civil Engineering Bangladesh University of Engineering and TechnologyDhaka 1000Bangladesh Georgia Tech Research Institute AtlantaGA 30332USA Stantec Inc. Edmonton T5J0K4Canada North West Pipe Company VancouverWA 98684USA

This paper presents an analytical approach for estimating frictional resistance to pipe movement at soil and external pipe surface of buried coated pressurized steel pipes relative to the internal thrust *** proposed analytical method was developed based on 36 experiments,which involved three coating types(cement mortar(CM),polyurethane type-I(PT-I),prefabricated plastic tape(PPT))on pipes’surfaces,three different soils(pea-gravel(PG),sand(S),silty-clay(SC)),and four simulated over burden depths above the pipe’s *** showed frictional resistance decreased with increasing over burden depth above the pipe’s *** degree of frictional resistance at the pipe-soil interface was found to be in the order of PG>SC>S for all coating variations and overburden *** coated pipe buried in all three types of soil produced significantly higher frictional resistance as compared to other coating *** on experimental data,the developed analytical introduced a dimensionless factor“Z”,which included effects of types of coatings,soil,and overburden depths for simplified rapid *** showed that the method provided a better prediction of frictional resistance forces,in comparison to previous analytical methods,which were barely close in predicting friction resistance for different coating variations,soil types,and overburden *** resistance force values reported herein could be considered conservative.

关键词： friction resistance force thrust force coated pressurized steel pipe soil type overburden depth

Spatio-Temporal Variability of Rainfall and Temperature and Their Effects on Pasture Variability over East Africa: Implication on the Cattle Grazing Areas

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Journal of Geoscience and Environment Protection 2024年第3期12卷 54-69页

作者： Natiko Peter Wang Wen Nyasulu matthews Raharivelo Sitraka Ny Aina Alupot Donnata School of Atmospheric Science Nanjing University of Information Science & Technology Nanjing China Uganda National Meteorological Authority Directorate of Station Networks Department of Instruments and Installations Kampala Uganda School of Ecology and Applied Meteorology Nanjing University of Information Science & Technology Nanjing China

Understanding the spatiotemporal variability of climatic parameters and their effects on pasture variability is vital for pasture management interventions over East Africa. The present study aims to assess the spatial-temporal variability of rainfall, temperature and Normalized Difference Vegetation Index (NDVI) (which is being used to assess pasture quality and productivity) over the region, between the period of 1982 and 2019. This study used annual mean values for rainfall, temperature and NDVI which were calculated for the period mentioned above. NDVI was derived from National Oceanic and Atmospheric Administration (NOAA) Global Area Cover (GAC) (NOAA-07-GAC) data. The rainfall data was acquired from the Climate Hazards Group Infrared Precipitation with Station (CHIRPS) while temperature is ERA5 reanalysis data sourced from the European Centre for Medium-Range Weather Forecasts (ECMWF). The study utilized the empirical orthogonal function (EOF) to identify patterns and dominant relationships between the climate variables. The correlation was calculated between rainfall, temperature and NDVI to assess the relationship among them. A non-parametric Mann-Kendall trends test was used to determine whether annual precipitation, temperature and NDVI had statistically increasing or decreasing trend. Results revealed a positive correlation between rainfall and NDVI while a negative correlation between NDVI and temperature. Positive correlation between rainfall and NDVI indicates that pasture health (quality and productivity), will improve accordingly. A negative correlation between temperature and NDVI indicates that pasture health will decrease with increase in temperature while improving with decreasing temperature. Outcome from this study suggests that changes in climatic variables influence the distribution of pasture in East Africa’s cattle grazing areas. The study hence recommends prioritisation of climatic (weather) information during pasture management over East A

关键词： NDVI Climatic Parameters EOF Pasture East Africa

Comparative Study of the Socioeconomic Characteristics and Digital Literacy Level of Agricultural Extension Personnel in Imo and Ebonyi States, South-East, Nigeria

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Agricultural Sciences 2024年第2期15卷 230-245页

作者： Ogbonnaya Okoro Aja Cyril Chigozie Asiabaka Anthony Okorie Ani Edna Chioma.matthews-Njoku Department of Agricultural Extension Federal University of Technology Owerri Nigeria

The study comparatively analysed the socioeconomic characteristics and digital literacy level of Agricultural Extension personnel (AEP) in Ebonyi and Imo States, South-East, Nigeria. The specific objectives were to describe the socioeconomic characteristics of agricultural extension personnel in Ebonyi and Imo States, and to ascertain the digital literacy level of AEP in the studied states. Purposive sampling technique was used to select 312 Agricultural Extension personnel (132 from Ebonyi State Agricultural Development Program and 180 from Imo State Agricultural Development Program) for the study. Data were collected through the use of validated and structured questionnaire, and administered through the help of well-trained enumerators. Data were analysed using simple descriptive statistical tools such as percentages mean score, standard deviation and weighted mean. Findings indicated that they were more male in the both States (55.3% and 57.8%) for Ebonyi and Imo State respectively and that the average age of AEP in Ebonyi and Imo States were 44.7 years and 49.2 years respectively. It was further revealed that the majority (77.3% and 82.8%) had ***./HND as their highest academic qualifications, belonged to professional organisations (62.1% and 75%), and were earning an average monthly income of N58,798 and N62,648 for Ebonyi and Imo State respectively. Also, it was revealed that their mean years of service were 12.4 years and 13.4 years for Ebonyi and Imo State respectively. Almost all of them (87.9% and 95.0%) own a smartphone, had access to the internet (80.3% and 90.0%), but do not own a laptop/ipad (82.6% and 72.8%) for Ebon-yi and Imo State respectively. Results further revealed that Agricultural extension personnel in both Ebonyi and Imo State respectively had low digital literacy level ( = 2.41 and 2.32). The study concluded that AEP in Ebonyi and Imo State respectively had similar socioeconomic characteristics and low level of digital literacy. The study

关键词： Agricultural Extension Personnel Digital Literacy Ebonyi State Imo State Socioeconomic Characteristics

Analysis of the Digital Skill Gap of Agricultural Extension Personnel in South-East, Nigeria

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Agricultural Sciences 2024年第9期15卷 1057-1070页

作者： Ogbonnaya Okoro Aja Chigozie Cyril Asiabaka Anthony Okorie Ani Edna Chioma.matthews-Njoku Department of Agricultural Extension Federal University of Technology Owerri Nigeria

The study analysed the digital skill gap of agricultural extension personnel on the use of digital technologies for extension services delivery in South-East, Nigeria. The specific objectives were to describe the socioeconomic characteristics of agricultural extension personnel in South-East Nigeria and identify the digital skill gaps among agricultural extension personnel in the area of study. Purposive sampling technique was used to select 364 Agricultural Extension personnel for the study. Data were collected through the use of structured questionnaire and were analysed using simple descriptive statistical tools such as percentages, mean score, and standard deviation. Findings indicated that most of the personnel were male (57.8%), within the age bracket of 38 - 47 years (62.9%), had ***./HND as their highest educational qualification (74.7%), married (86.3%), and had a household size of 6 - 10 Persons (57.7%). It was further revealed that the majority (70.1%) were members of professional organization, earned a monthly income of N50,001.00 - N100,000.00 (65.7%), had a work experience of 11 - 15 years (51.1%), and owned a smartphone/ iPad/laptop (91.5%). Findings further indicated that they had moderate skill gap in Basic Computer skills (Mean = 4.32), and digital communication and collaboration skills (Mean = 4.26). Findings also showed that they had a high skill gap in digital technical skills (Mean = 2.46), digital data analysis skills (Mean = 2.09), digital content creation skills (Mean = 2.43), digital ethical skills (Mean = 2.79), multimedia production skills (Mean = 2.81), and video library management skills (Mean = 2.39). The study concluded that though there exists a high digital skill gap among agricultural extension personnel in South-East, Nigeria, their socioeconomic characteristics are capable of supporting the implementation of digital extension services in the area. The study recommended that the management of Agricultural Development Programs in

关键词： Agricultural Extension Personnel Socioeconomic Characteristics Digital Skill Gap South-East Nigeria

Design of bidirectional frictional behaviour for tactile contact using ellipsoidal asperity micro-textures

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Friction 2022年第5期10卷 762-771页

作者： Dmitrii SERGACHEV David matthews Emile VAN DER HEIDE Laboratory for Surface Technology and Tribology Faculty of Engineering TechnologyUniversity of TwenteOverissel 7522 LIWEnschedethe Netherlands Faculty of Engineering and Architecture Ghent UniversitEast Flanders 9000GhenBelgium

Tactile perception and friction can be modified by producing a deterministic surface *** of surface feature arrangement and texture symmetry can produce an anisotropic frictional *** is generally achieved through skin hysteresis by promoting its *** work investigates whether a bidirectional friction can be created with microscale ellipsoidal asperity textures,thus relying on the adhesive component of *** this purpose,four textured samples with various asperity dimensions were moulded with a silicone rubber having an elastic modulus comparable to that of the *** of friction measurements were conducted in-vivo in two sliding directions with a range of normal loads up to 4 *** element method(FEM)was used to study elastic deformation effects,explain the observed friction difference,and predict surface material *** performed perpendicular to the asperity major radii showed consistently higher friction coefficients than that during parallel *** the larger asperity dimensions,a change of the sliding direction increased friction up to a factor of *** numerical analysis showed that this effect is mostly related to elastic asperity *** friction differences can be further controlled by asperity dimensions,spacing,and material properties.

关键词： surface texture sliding direction skin friction elastomer

Determination of broadband atmospheric turbidity from global irradiance or photovoltaic power data using deep neural nets

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Energy and AI 2023年第4期14卷 17-30页

作者： Dax K.matthews University of Hawaii at Manoa Hawaii Natural Energy Institute(HNEI)1680 East West RoadPOST 109Honolulu96822HIUSA

Photovoltaic technologies provide significant capacity to electric grids,however,resource variability and production uncertainty complicate power balancing and reserve management.A crucial step in predicting solar generation is determining clear-sky ***-sky attenuation can be modeled using broadband atmospheric turbidity factors,but model accuracy is dependent on the measurements used to determine the current and future state of aerosol loading and water vapor content,which requires close proximity measurements,in time and space,to account for turbidity *** measurements,though,are only available in near real-time at a limited,and decreasing,number of *** paper proposes a new method for estimating time-varying local turbidity conditions from more readily available pyranometer or PV output *** method employs a long short-term memory recurrent neural network to distill the turbidity-driven signal from global irradiance(or global irradiance driven)observations,despite an inherent dampening *** method is developed to operate in near real-time for solar forecasting *** examines the ability of the method to(1)reproduce turbidity estimates derived from historical measurements of beam irradiance under clear-sky conditions;and(2)provide input for clear-sky models in the form of persistence forecasts generated from daily mean values.

关键词： Solar power forecasting Broadband atmospheric turbidity Clear-sky modeling