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Lithological and Si–O–S isotope geochemistry:constraints on the origin and genetic environment of the selenium(Se)-rich siliceous rocks in Enshi,Hubei Province,China

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Acta Geochimica 2021年第1期40卷 89-105页

作者： Caixia Feng Shen Liu Ian M.Coulson State Key Laboratory of Continental Dynamics and Department of Geology Northwest UniversityXi'an 710069China Solid Earth Studies Laboratory Department of GeologyUniversity of ReginaReginaSK S4S 0A2Canada

Se-rich black rock series of the Middle and Late Permian system is widely distributed in Enshi Prefecture with an exposed area of 850 km~2,among which the unique Yutangba black rock series independent selenium deposit with industrial mining significance in the world is ***,the source and metallogenic mechanisms of Se are still *** general,terrestrial weathering and submarine hydrothermal processes are the main source end members of Si and Se,and the related siliceous rocks record the deposition process of Si and Se from different *** study of lithofacies and paleogeography shows that western Hubei belongs to the near eastwest turn of the Yangzi platform in the Middle and Late Permian and becomes an inter-platform basin with nearly north-south ***,the comparative study of the Yutangba deposit and the selenium-rich black rock series in the northern Shadi with high selenium content is expected to reveal the provenance evolution of the two sections in space,and further restrict the Se mineralization mechanism in the Enshi *** the element geochemistry study,the black rock series in two study areas may have formed in a transitional position of either the continental margin or continental slope,in the process of sedimentary,more terrigenous clastic materials *** are rich in lithophile elements V and Cr.δU>1.0,U/Th and V/(V+Ni)ratio indicate that the Se-rich strata of black rock series in the Enshi areas occurred in an anoxic reducing environment and formed in an environment between the ocean basin and the continental *** Si-O isotope geochemistry,the original Si source of the study area is thought to relate to a volcanic eruption,which leads to the enrichment of Si in the *** determined values of S isotope in the black rock series of the two study areas both show the characteristics related to organic reduction/biogenic.

关键词： Se-rich siliceous rocks Geochemistry Si–O–S isotope Origin Sedimentary environment

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Weed detection in canola fields using maximum likelihood classification and deep convolutional neural network

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Information Processing in Agriculture 2020年第4期7卷 535-545页

作者： Muhammad Hamza Asad Abdul Bais Electronic Systems Engineering Faculty of Engineering and Applied ScienceUniversity of ReginaSaskatchewanCanada

Herbicide use is rising globally to enhance food production,causing harm to environment and the *** agriculture suggests variable-rate herbicide application based on weed densities to mitigate adverse effects of *** weed density estimation using advanced computer vision techniques like deep learning requires large labelled agriculture *** large agriculture data at pixel level is a time-consuming and tedious *** this paper,a methodology is developed to accelerate manual labelling of pixels using a two-step *** the first step,the background and foreground are segmented using maximum likelihood classification,and in the second step,the weed pixels are manually *** labelled data is used to train semantic segmentation models,which classify crop and background pixels as one class,and all other vegetation as the second *** paper evaluates the proposed methodology on high-resolution colour images of canola fields and makes performance comparison of deep learning meta-architectures like SegNet and UNET and encoder blocks like VGG16 and ***-50 based SegNet model has shown the best results with mean intersection over union value of 0.8288 and frequency weighted intersection over union value of 0.9869.

关键词： Weed detection Semantic segmentation Variable rate herbicide Maximum likelihood classification

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Drought changes and the mechanism analysis for the North American Prairie

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Journal of Arid Land 2013年第1期5卷 1-14页

作者： Ge YU DaveSAUCHYN YongFei LI State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China Prairie Adaptation and Research Collaborative University of Regina Regina $4S 7J7 Canada

The worst droughts in the central part of the North American Prairie in the past several hundred years have been reconstructed from tree-ring chronologies, suggesting that some drought years have exceeded the se- verity shown by the gauge record. A general circulation model of the Geophysical Fluid Dynamics Laboratory （GFDL） has simulated climate changes for the area during the past 250 years driven by c^imatic forces, providing scenarios of extreme climate that can further diagnose the mechanisms. This study refined the drought signals from the tree ring data and GFDL modeling at inter-annual and decadal time scales and analyzed the potential mecha- nisms driving the droughts. Results showed that drought years with summer precipitation Ilower than the 10th per- centiles occurred during 1777-1789, 1847-1861 and 1886-1879 AD in the area. Both tree rings and model re- vealed that the frequency of droughts has been relatively consistent in a similar timing andl frequency with climate change. Monte Carlo analysis have detected that the tree ring chronologies have recorded drought years with probabilities of 9.3%-12.8%, and the model has simulated the droughts with probabilities 5..7%-17.8%. Under CO2 and aerosol forcing, the GFDL modeled the drought recurrences of 13 years and 25 years, which are very syn- chronous changes with tree rings and consistent with gauge records. The 20-a and 10-a time scale reoccurrences of droughts are very consistent with solar radiation cycles, and similar to the length of cycles in oceanic records, suggesting that terrestrial precipitation modeling is properly driven from sun-land-sea dynamics. Detected severity, variability and return periods of droughts from the present study make potential improvements in drought predictions and constructing scenarios for climate impacts and adaptation strategies.

关键词： drought tree ring chronology climate modeling probability central Prairie

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Learning from a carbon dioxide capture system dataset: Application of the piecewise neural network algorithm

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Petroleum 2017年第1期3卷 56-67页

作者： Veronica Chan Christine Chan Energy Informatics Laboratory Faculty of Engineering and Applied ScienceUniversity of ReginaReginaSK S4S0A2Canada

This paper presents the application of a neural network rule extraction algorithm,called the piecewise linear artificial neural network or PWL-ANN algorithm,on a carbon capture process system *** objective of the application is to enhance understanding of the intricate relationships among the key process *** algorithm extracts rules in the form of multiple linear regression equations by approximating the sigmoid activation functions of the hidden neurons in an artificial neural network(ANN).The PWL-ANN algorithm overcomes the weaknesses of the statistical regression approach,in which accuracies of the generated predictive models are often not satisfactory,and the opaqueness of the ANN *** results show that the generated PWL-ANN models have accuracies that are as high as the originally trained ANN models of the four datasets of the carbon capture process *** analysis of the extracted rules and the magnitude of the coefficients in the equations revealed that the three most significant parameters of the CO_(2) production rate are the steam flow rate through reboiler,reboiler pressure,and the CO_(2) concentration in the flue gas.

关键词： Carbon dioxide capture process system Artificial neural network Rule extractions Non-linear modeling Linear regression

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Geochemical constraints on the origin of Early Cretaceous alkaline intrusions and its tectonic implication,Sulu Orogenic Belt,Eastern North China Craton

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Acta Geochimica 2020年第5期39卷 616-641页

作者： Shen Liu Caixia Feng Yan Fan Kairui Tai Tianjing Gao Ian M.Coulson State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi'an 710069China Solid Earth Studies Laboratory.Department of Geology University of Regina.ReginaSK S4S 0A2Canada

Post-orogenic alkaline intrusions from the Sulu Orogenic Belt of eastern North China Craton consist of A-type *** this study,we report U-Pb zircon ages,geochemical data,Sr-Nd-Pb,and zircon Hf isotopic data for these *** LA-ICP-MS U-Pb zircon analyses yield consistent ages ranging from 127.1±2.4 to 119.5±4.8 Ma for four *** alkaline rocks are characterized by high total alkalis(K2 O+Na2 O=8.32-10.11 wt%),light rare-earth element enrichment,and heavy rare-earth element depletion,with a wide range(La/Yb)N values(20-48),moderate negative Eu anomalies(Eu/Eu*=0.50-0.74),enrichment in large-ion lithophile elements(LILEs,i.e.,Rb,Th,U and Pb),and depletion in Ba,Sr and high field strength elements(HFSEs,i.e.,Nb,Ta,and Ti),high(87Sr/86Sr)i ranging from 0.708 to 0.7089,low sNd(t)values from-19.4 to-16.8,(206Pb/204Pb)i=16.751-16.935,(207Pb/204Pb)i=15.381-15.535,(208-Pb/204Pb)i=37.472-37.838,negativeεHf(t)values between-21.3 and-25.7 for the magmatic zircons,and larger TDM2 model ages from 2.5 to 2.8 *** results suggest that the rocks were derived from a common enriched lithospheric mantle source that was metasomatized by foundered lower crustal eclogitic materials before magma ***,the geochemical and isotopic feature implies that the primary magma of these rocks originated through partial melting of ancient lithospheric mantle that was variably hybridized by melts derived from lower crust *** rocks in this study may have been generated by subsequent fractionation of potassium feldspar,plagioclase,ilmenite,and/or ***,negligible crustal contamination occurred during the diagenesis process.

关键词： Post-orogenic magmatism Alkaline rocks Contamination Sulu Orogenic Belt North China Craton

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Extensive experimental investigation of the effect of drainage height and solvent type on the stabilized drainage rate in vapour extraction (VAPEX) process

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Petroleum 2015年第3期1卷 187-199页

作者： Mehdi Mohammadpoor Farshid Torabi Petroleum Systems Engineering Faculty of Engineering and Applied ScienceUniversity of ReginaReginaSK S4S 0A2Canada

The low cost of the injected solvent,which can be also recovered and recycled,and the applicability of VAPEX technique in thin reservoirs are among the main advantages of VAPEX process compared to thermal heavy oil recovery *** this research,an extensive experimental investigation is carried out to first evaluate the technical feasibility of utilization of various solvents for VAPEX *** the effect of drainage height on the stabilized drainage rate in VAPEX process was studied by conducting series of experiments in two large-scale 2D VAPEX models of 24.5 cm and 47.5 cm *** models were packed with low permeability Ottawa sand(#530)and saturated with a heavy oil sample from Saskatchewan heavy oil reservoirs with viscosity of 5650 mPa ***,butane,methane,carbon dioxide,propane/carbon dioxide(70%/30%)and propane/methane(70%/30%)were considered as respective solvents for the experiments,and a total of twelve VAPEX tests were carried ***,separate experiments were carried out at the end of each VAPEX experiment to measure the asphaltene precipitation at various locations of the VAPEX *** was found that injecting propane would result in the highest drainage rate and oil recovery *** analysis of results showed stabilized drainage rate significantly increased in the larger physical model.

关键词： Vapour extraction Drainage height Solvent type Stabilized drainage rate Experimental studies

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Total phosphorus accident pollution and emergency response study based on geographic information system in Three Gorges Reservoir area

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Frontiers of Environmental Science & Engineering 2020年第3期14卷 113-125页

作者： Aifeng Zhai Xiaowen Ding Lin Liu Quan Zhu Guohe Huang MOE Key Laboratory of Resources and Environmental System Optimization College of Environmental Science and EngineeringNorth ChinaElectric Power UniversityBeijing 102206China Institute for Energy Environment and Sustainable CommunitiesUniversity of ReginaS4S 7H9ReginaCanada

In recent years,sudden water pollution accidents in China's rivers have become more frequent,resulting in considerable effects on environmental ***,it is necessary to simulate and predict pollution *** and prediction provide strong support for emergency disposal and disaster *** paper describes a new two-dimensional water quantity and the quality model that incorporates a digital elevation model into the geographic information *** model is used to simulate sudden water pollution accidents in the main stream of the Yangtze River and Jialing River in the Chongqing section of the Three Gorges Reservoir *** sectional velocity distribution and concentration change of total phosphorus are then analyzed under four hydrological *** results show that the proposed model accurately simulates and predicts the concentration change and migration process of total phosphorus under sudden water pollution *** speed of migration and diffusion of pollutants is found to be greatest in the flood season,followed by the water storage period,drawdown season,and dry season,in that *** selection of an appropriate water scheduling scheme can reduce the peak concentration of river *** study enables the impact of pollutants on the ecological environment of river water to be alleviated,and provides a scientific basis for the emergency response to sudden water pollution accidents in the Three Gorges Reservoir area.

关键词： Sudden water pollution accident Total phosphorus Predictive model Contaminant simulation Water scheduling Measure

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Hydrodynamic analysis of clastic injection and hydraulic fracturing structures in the Jinding Zn-Pb deposit,Yunnan,China

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Geoscience Frontiers 2012年第1期3卷 73-84页

作者： Guoxiang Chi Chunji Xue Hairuo Qing Wei Xue Jiangwei Zhang Yunqiang Sun Department of Geology University of ReginaReginaSK S4S OA2Canada State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China

The Jinding Zn-Pb deposit has been generally considered to have formed from circulating basinal fluids in a relatively passive way, with fluid flow being controlled by structures and sedimentary facies, similar to many other sediments-hosted base metal deposits. However, several recent studies have revealed the presence of sand injection structures, intrusive breccias, and hydraulic fractures in the open pit of the Jinding deposit and suggested that the deposit was formed from explosive release of overpres- sured fluids. This study reports new observations of fluid overpressure-related structures from under- ground workings （Paomaping and Fengzishan）, which show clearer crosscutting relationships than in the open pit. The observed structures include： 1） sand （--rock fragment） dikes injecting into fractures in solidified rocks; 2） sand （~rock fragment） bodies intruding into unconsolidated or semi-consolidated sediments; 3） disintegrated semi-consolidated sand bodies; and 4） veins and breccias formed from hydraulic fracturing of solidified rocks followed by cementation of hydrothermal minerals. The development of ore minerals （sphalerite） in the cement of the various clastic injection and hydraulic fractures indicate that these structures were formed at the same time as mineralization. The development of hydraulic fractures and breccias with random orientation indicates small differential stress during mineralization, which is different from the stress field with strong horizontal shortening prior to miner- alization. Fluid flow velocity may have been up to more than 11 m/s based on calculations from the size of the fragments in the clastic dikes. The clastic injection and hydraulic fracturing structures are interpreted to have formed from explosive release of overpressured fluids, which may have been related to either magmatic intrusions at depth or seismic activities that episodically tapped an overpressured fluid reservoir. Because the clastic injection and hydraul

关键词： Hydrodynamics Clastic injection Hydraulic breccia Hydraulic fracturesJinding Fluid overpressure

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Identifying,exploring,and interpreting time series shapes in multivariate time intervals

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Visual Informatics 2023年第1期7卷 77-91页

作者： Gota Shirato Natalia Andrienko Gennady Andrienko Fraunhofer IAIS Sankt Augustin53757Germany University of Bonn Regina-Pacis-Weg 3Bonn53113Germany city University of LondonNorthampton SquareLondonEC1V 0HBUK

We introduce a concept of episode referring to a time interval in the development of a dynamic phenomenon that is characterized by multiple time-variant attributes.A data structure representing a single episode is a multivariate time *** analyse collections of episodes,we propose an approach that is based on recognition of particular patterns in the temporal variation of the variables within *** episode is thus represented by a combination of *** this representation,we apply visual analytics techniques to fulfil a set of analysis tasks,such as investigation of the temporal distribution of the patterns,frequencies of transitions between the patterns in episode sequences,and co-occurrences of patterns of different variables within same *** demonstrate our approach on two examples using real-world data,namely,dynamics of human mobility indicators during the COVID-19 pandemic and characteristics of football team movements during episodes of ball turnover.

关键词： Temporal patterns Multivariate time series Time intervals

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Hydrodynamic regime as a major control on localization of uranium mineralization in sedimentary basins

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Science China Earth Sciences 2014年第12期57卷 2928-2933页

作者： CHI GuoXiang XUE ChunJi Department of Geology University of Regina State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

Uranium deposits in sedimentary basins can be formed at various depths,from near surface to the *** many factors may have played a role in controlling the location of mineralization,examination of various examples in the world,coupled with numerical modeling of fluid flow,indicates that the hydrodynamic regime of a basin may have exerted a major control on the localization of uranium *** a basin is strongly overpressured,due to rapid sedimentation,abundance of low-permeability sediments or generation of hydrocarbons,fluid flow is dominantly upward and uranium mineralization is likely limited at shallow *** a basin is moderately overpressured,upward moving fluids carrying reducing agents may meet downward moving,oxidizing,uranium-bearing fluids in the middle of the basin,forming uranium deposits at moderate *** a basin is weakly or not overpressured,either due to slow sedimentation or dominance of high-permeability lithologies,minor topographic disturbance or density variation may drive oxidizing fluids to the bottom of the basin,leaching uranium either from the basin or the basement,forming unconformity-type uranium *** is therefore important to analyze the hydrodynamic regime of a basin in order to predict the most likely type and location of uranium deposits in the basin.

关键词： uranium deposits localization sedimentary basins hydrodynamic regime fluid overpressure

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