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2019

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Articles 3241 - 3270 of 15928

Full-Text Articles in Physical Sciences and Mathematics

Sub-Tidal Hydrodynamics Of The Multi-Inlet Lake Pontchartrain Estuary Influenced By Mississippi River Diversion And Wind Associated With Atmospheric Fronts, Wei Huang Aug 2019

Sub-Tidal Hydrodynamics Of The Multi-Inlet Lake Pontchartrain Estuary Influenced By Mississippi River Diversion And Wind Associated With Atmospheric Fronts, Wei Huang

LSU Doctoral Dissertations

In-situ observations and a Finite Volume Community Ocean Model (FVCOM) are used to investigate the cold front induced sub-tidal hydrodynamics of Lake Pontchartrain, a semi-enclosed low-salinity estuary with multiple inlets connecting to the open ocean. Observations show that the sub-tidal hydrodynamic responses are highly correlated with the meteorological parameters during cold front events. Model results indicate that, under barotropic conditions, the remote wind effect has the greatest contribution to the overall water level variation, while the local wind stress during cold front events determines the slope for the water level inside the estuary. An examination of a quasi-steady state force …

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Multicomponent Model Of Crustal Stress At Cajon Pass, Southern California With Implications For Stress Field Heterogeneity, Elliott Conley Helgans Aug 2019

Multicomponent Model Of Crustal Stress At Cajon Pass, Southern California With Implications For Stress Field Heterogeneity, Elliott Conley Helgans

LSU Master's Theses

Earthquake processes in plate boundary settings are chiefly controlled by the in situ crustal stress field. Knowledge of the relative importance of various active processes acting on a fault system is necessary to understand the mechanics of faulting. This is of extreme importance to the Cajon Pass region of southern California, which may function as an earthquake gate, imposing control on large multifault ruptures. We model the in situ stress field at seismogenic depth in Cajon Pass by balancing the orientation of the modern stress field inferred from earthquake focal mechanisms against the superposition of the far field tectonic driving …

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Near-Field Effects On Partially Coherent Light Scattered By An Aperture, Milo W. Hyde Iv, Michael J. Havrilla Aug 2019

Near-Field Effects On Partially Coherent Light Scattered By An Aperture, Milo W. Hyde Iv, Michael J. Havrilla

Faculty Publications

We investigate how the near field affects partially coherent light scattered from an aperture in an opaque screen. Prior work on this subject has focused on the role of surface plasmons, and how they affect spatial coherence is well documented. Here, we consider other near-field effects that might impact spatial coherence. We do this by examining the statistics of the near-zone field scattered from an aperture in a perfect electric conductor plane—a structure that does not support surface plasmons. We derive the near-field statistics (in particular, cross-spectral density functions) by applying electromagnetic equivalence theorems and the Method of Moments. We …

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Who Can Act? Critical Assumptions At The Foundations Of Statistical Analysis, Peter J. Taylor Aug 2019

Who Can Act? Critical Assumptions At The Foundations Of Statistical Analysis, Peter J. Taylor

Working Papers on Science in a Changing World

Thinking about a simple teaching example on the t-test for comparing the average (mean) for some measurement in a group versus the average in another led me to articulate a sequence of thoughts and questions about the foundations of statistical analysis. In particular, my inquiry explores contrasts between: the statistical emphasis on averages or types around which there is variation or noise; variation as a mixture of types; the dynamics (or heterogeneous mix of dynamics) that generated the data analyzed; and participatory restructuring of these dynamics in the future. Two key issues are: Who is assumed to be able to …

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Singlet-Doublet Dirac Dark Matter And Neutrino Masses, Diego Restrepo, Andrés Rivera, Walter Tangarife Aug 2019

Singlet-Doublet Dirac Dark Matter And Neutrino Masses, Diego Restrepo, Andrés Rivera, Walter Tangarife

Physics: Faculty Publications and Other Works

We examine an extension of the Standard Model that addresses the dark matter puzzle and generates Dirac neutrino masses through the radiative seesaw mechanism. The new field content includes a scalar field that plays an important role in setting the relic abundance of dark matter. We analyze the phenomenology in the light of direct, indirect, and collider searches of dark matter. In this framework, the dark matter candidate is a Dirac particle that is a mixture of new singlet-doublet fields with mass mχ01≲1.1  TeV. We find that the allowed parameter space of this model is broader than the well-known Majorana …

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Going Big: A Large-Scale Study On What Big Data Developers Ask, Mehdi Bagherzadeh, Raffi T. Khatchadourian Aug 2019

Going Big: A Large-Scale Study On What Big Data Developers Ask, Mehdi Bagherzadeh, Raffi T. Khatchadourian

Publications and Research

Software developers are increasingly required to write big data code. However, they find big data software development challenging. To help these developers it is necessary to understand big data topics that they are interested in and the difficulty of finding answers for questions in these topics. In this work, we conduct a large-scale study on Stackoverflow to understand the interest and difficulties of big data developers. To conduct the study, we develop a set of big data tags to extract big data posts from Stackoverflow; use topic modeling to group these posts into big data topics; group similar topics into …

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Controlling The Spatial Coherence Of An Optical Source Using A Spatial Filter, Milo W. Hyde Iv Aug 2019

Controlling The Spatial Coherence Of An Optical Source Using A Spatial Filter, Milo W. Hyde Iv

Faculty Publications

This paper presents the theory for controlling the spectral degree of coherence via spatial filtering. Starting with a quasi-homogeneous partially coherent source, the cross-spectral density function of the field at the output of the spatial filter is found by applying Fourier and statistical optics theory. The key relation obtained from this analysis is a closed-form expression for the filter function in terms of the desired output spectral degree of coherence. This theory is verified with Monte Carlo wave-optics simulations of spatial coherence control and beam shaping for potential use in free-space optical communications and directed energy applications. The simulated results …

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Dna Recovery From Handwritten Documents Using A Novel Vacuum Technique, Patrick M. Mclaughlin Aug 2019

Dna Recovery From Handwritten Documents Using A Novel Vacuum Technique, Patrick M. Mclaughlin

Student Theses

Investigations of many crimes such as robberies, kidnappings, and terrorism are often associated with the recovery of a paper document which has been written by the perpetrator. Paper can provide a variety of forensic evidence such as DNA, latent fingermarks, and indented writing. The focus of this study was the collection of probative DNA profiles from the text region of a handwritten note through a vacuum suction device without altering or destroying the document. Collection of DNA evidence was carried out in two separate groups. The first group involved 11 volunteers providing a handwritten note sample with unwashed hands. The …

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The Invasion Ecology Of Ivy (Hedera Spp.) In Portland's Forest Park, Eric Paul Butler Aug 2019

The Invasion Ecology Of Ivy (Hedera Spp.) In Portland's Forest Park, Eric Paul Butler

Dissertations and Theses

Invasive ivy (Hedera spp.) has extensive impacts on Pacific Northwest urban forests, many of which are not yet fully understood. In this study of Forest Park, Portland, Oregon, I evaluated several environmental variables obtained or derived from monitoring datasets at three spatial scales to determine the following: how ivy is spatially distributed; what factors are most correlated with ivy abundance; and how ivy abundance influences shrub community composition. I found that ivy is significantly clustered at all scales with multiple apparent epicenters along the park's urban periphery. Using NMDS ordination, I determined that ivy is a significant factor in …

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Effect Of Nmr Technology-Based Ultrasonic Frequency On Stimulated Cracking Of Coal, Ma Huiteng, Zhai Cheng, Xu Jizhao, Sun Yong Aug 2019

Effect Of Nmr Technology-Based Ultrasonic Frequency On Stimulated Cracking Of Coal, Ma Huiteng, Zhai Cheng, Xu Jizhao, Sun Yong

Coal Geology & Exploration

In order to further study the effect of ultrasonic frequency on the stimulated cracking effect of coal, the paper conducted the crack experiment on the original coal samples by using the ultrasonic generation meter, and measured the coal by using the NMR equipment through analyzing the T2 curve, the changes of pore structure before and after coal sample cracking were deeply studied. The results show that the pore structure of coal can be effectively improved by the ultrasonic wave. After the crack induced by the ultrasonic wave, the pore quantity inside the coal increased and the total porosity, effective …

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Influence Of Internal Friction Angle On Damage Constitutive Model Of Freeze-Thaw Rock, Yuan Chao, Zhang Huimei, Meng Xiangzhen, Yang Gengshe, Wu Luyuan Aug 2019

Influence Of Internal Friction Angle On Damage Constitutive Model Of Freeze-Thaw Rock, Yuan Chao, Zhang Huimei, Meng Xiangzhen, Yang Gengshe, Wu Luyuan

Coal Geology & Exploration

Based on Weibull random distribution and damage mechanics theory, starting from the characteristics of rock deformation process, the Drucker-Prager criterion was used to establish a damage constitutive model that can reflect the characteristics of rock various deformation stages. Through the conventional triaxial compression test of frozen-thawed sandstone, the Mohr stress circle was used to obtain the cohesion and internal friction angle of the sandstone under different freeze-thaw cycles. The model theoretical curve and the test curve of freeze-thaw sandstone were compared to verify the model rationality. By varying the internal friction angle, whether the friction angle has an effect on …

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Study On Slope Stability And The Effect Of Highfill On The Mechanical Properties Of Red Clay Foundation, Gao Shengxiang, Xu Qiang, Ma Hongyu, Wu Shenglin, Wu Kang, Liu Peng, Wu Zehui Aug 2019

Study On Slope Stability And The Effect Of Highfill On The Mechanical Properties Of Red Clay Foundation, Gao Shengxiang, Xu Qiang, Ma Hongyu, Wu Shenglin, Wu Kang, Liu Peng, Wu Zehui

Coal Geology & Exploration

This paper takes a highfill slope in Anning in Yunnan Province as a case, using investigation, monitoring and other methods, on the basis of the distribution characteristics of red clay, the physical and mechanical properties of red clay before and after filling were analyzed, then the stability of slope was studied by numerical simulation software. The results show that the physical and mechanical indexes of the red clay foundation decrease first and then increase before and after the fill project, the stability of the fill slope shows the trend of decrease first and then increase. The ground fissures in the …

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Instability Mechanism And Anti-Sloughing Drilling Fluid Technique For Deep Coal Seam Of Tarim Basin, Li Heng, He Shiming, Tang Ming, Li Ning, Yang Pei, Zhang Zhen Aug 2019

Instability Mechanism And Anti-Sloughing Drilling Fluid Technique For Deep Coal Seam Of Tarim Basin, Li Heng, He Shiming, Tang Ming, Li Ning, Yang Pei, Zhang Zhen

Coal Geology & Exploration

In view of the complicated problems of drilling fluid leakage and hole collapse during the drilling of deep coalbed in Tarim basin, the microstructure and physical and chemical properties of coal were tested by vitrinite reflectance analysis, X ray diffraction and scanning electron microscope, and the mechanism of coal seam instability was confirmed. The fixed carbon content of the coal exceeds 60%, the vitrinite reflectance is greater than 1.1%, and coal have high degree of coalification, is brittle and easy to break. The total amount of clay mineral is less than 25%, and there is no strong water-sensitive mineral montmorillonite …

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Modification Function Of Magnetic Treatment On Grouting Clay Slurry, Xue Weifeng, Wang Sujian, Deng Zengshe, Huang Kejun, Han Lei, Ji Ruijun, Liang Shaojian Aug 2019

Modification Function Of Magnetic Treatment On Grouting Clay Slurry, Xue Weifeng, Wang Sujian, Deng Zengshe, Huang Kejun, Han Lei, Ji Ruijun, Liang Shaojian

Coal Geology & Exploration

Clay slurry was treated through magnetization. The characteristics of the physical property change of the clay slurry after magnetic treatment such as viscosity, density, pH value, conductivity, syneresis rate, concretion rate and anti-permeability were studied. After magnetic treatment, density, viscosity and syneresis rate of the clay slurry decrease, pH, conductivity and concretion rate increase, the syneresis rate and the concretion rate are improved with the magnetization time. The magnetic treatment improves the rheological property of clay slurry, the anti-permeability performance of the cemented body of clay slurry after magnetic treatment rises greatly compared to the cemented body of clay slurry …

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Management Of National Planned Coal Mining Areas And Discrimination With Coal Mining Areas, Wang Xiangsheng, Wang Meng, Liu Jingchun Aug 2019

Management Of National Planned Coal Mining Areas And Discrimination With Coal Mining Areas, Wang Xiangsheng, Wang Meng, Liu Jingchun

Coal Geology & Exploration

In view of the confusion between national planned coal mining areas and coal mining areas, based on the relevant standards and notices, the definitions of national planned coal mining areas and coal mining areas are interpreted in detail. This paper introduces the basic situation of the first and second batches of national planned coal mining areas and the《National Mineral Resources Planning (2016-2020)》. The differences between the two are expounded in detail from the aspects of delineation purpose, delimitation basis and formation period. It is pointed out that the competent department of national planned coal mining areas is the Ministry of …

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Microseismic Test And Numerical Simulation Analysis Of Floor Failure Depth Of Isolated Coal Mining Face, Zhao Chunhu Aug 2019

Microseismic Test And Numerical Simulation Analysis Of Floor Failure Depth Of Isolated Coal Mining Face, Zhao Chunhu

Coal Geology & Exploration

Aiming at the damage of coal seam floor caused by mining in isolated coal mining face, taking 11913 isolated coal mining face in Gequan coal mine of Hebei Province as the research object, and using KJ959 coal mine microseismic monitoring system to detect the floor failure depth. It is recognized that the microseismic events mainly occur in the roadway of the isolated coal mining face during the mining process, and the maximum vertical failure depth is about 20~25m; Moreover, using the COMSOL multi-physical field numerical simulation platform, the variation of in-situ stress and failure law of coal seam floor under …

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Coalbed Methane Migration Mechanism Under Adsorption-Desorption Condition In Coal, Liu Yongqian, Zhang Shulin, Shu Longyong Aug 2019

Coalbed Methane Migration Mechanism Under Adsorption-Desorption Condition In Coal, Liu Yongqian, Zhang Shulin, Shu Longyong

Coal Geology & Exploration

The migration law of coalbed methane(CBM) with adsorption has always been the focus of attention in the field of coalbed methane geology. In order to study the mechanism of CBM migration under adsorption-desorption state, the deduction of gas adsorption-desorption equation and theoretical analysis of gas diffusion-seepage in porous media were carried out, and new viewpoints were put forward by means of experimental analysis of CBM migration. The results identified that:(1) for the CBM migration, pore structure of coal body has the storage-resistance effect, the dual functions of gas storage and gas pressure drop form the basic feature of coal matrix, …

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Geological Characteristics And High Efficiency Development Technology Of Coalbed Methane In Duijiangnan Coal Mine, Guizhou Province, Gong Zewen Aug 2019

Geological Characteristics And High Efficiency Development Technology Of Coalbed Methane In Duijiangnan Coal Mine, Guizhou Province, Gong Zewen

Coal Geology & Exploration

The development progress of coalbed methane in Duijiangnan mine field is slow. The main problems are low drilling efficiency, serious cementing leakage, long fracturing transformation period and low single well production in the block. Objectively evaluating the geological characteristics and development technology of coalbed methane is very im-portant for coalbed methane in the future. The coalbed thickness, coal body structure, reservoir pressure, gas content and permeability are systematically studied, combining with the past drilling, fracturing and drainage practices. It is proposed that directional wells are the main method of coalbed methane development in the coalfield. The coal seam M18 which …

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Research And Application Of Cbm Surface Extraction Based On Coal Mine With “Gas Drainage First, Construction Later” And Resource Development, Wang Jing, Yao Tuanqi, Cheng Bin Aug 2019

Research And Application Of Cbm Surface Extraction Based On Coal Mine With “Gas Drainage First, Construction Later” And Resource Development, Wang Jing, Yao Tuanqi, Cheng Bin

Coal Geology & Exploration

Aiming at the safety index put forward by "gas drainage first, construction later" of coal mine at present and the resource characteristics of many coal seams in northern Guizhou Province, and at the same time making up for the lack of systematization and large blind area of surface gas drainage deployment at present, this paper took Duijiangnan coal mine as an example to carry out the research of coal bed methane surface drainage deployment. Based on the complex topographic conditions, coal seam development characteristic(multiple layers, thin thickness, group distribution), coal body structure, development and deployment requirements in this area, the …

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Advances On Geological-Geochemical Research Of Coal-Type Uranium In China, Zhou Xianqing, Qin Yong, Lu Lu Aug 2019

Advances On Geological-Geochemical Research Of Coal-Type Uranium In China, Zhou Xianqing, Qin Yong, Lu Lu

Coal Geology & Exploration

There is a huge gap in uranium resources in China. Only developing traditional uranium resources is unable to meet the increasing demand in energy and national defense construction. The exploitation and utilization of coal-type uranium resources can relieve the pressure of demand for uranium resources to a certain extent. By summarizing the research results of coal-type uranium in recent years, the ore location, uranium content range, formation time and distribution range of coal-bearing strata of major coal-type uranium deposits in China, and the definition criteria of coal-type uranium are given, which provides a basis for the classification of coal-type uranium …

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Inversion Analysis Of Earth Pressure For Limited Soil Between Oblique Support Retaining Foundation Pit And Adjacent Basement, Zhang Guomao, Peng Wenxiang Aug 2019

Inversion Analysis Of Earth Pressure For Limited Soil Between Oblique Support Retaining Foundation Pit And Adjacent Basement, Zhang Guomao, Peng Wenxiang

Coal Geology & Exploration

In order to study the distribution of earth pressure for limited soil between oblique support retaining foundation pit and adjacent basement, back analysis of site monitoring data of a foundation pit was studied. Based on the improved cubic spline method of the trial algorithm, Matlab software was used to calculate the bending moment value of the supporting structure and the earth pressure value behind the pile. The results show the earth pressure of limited soil is influenced by displacement mode, non-limit state and boundary conditions. The active earth pressure of limited soil above the excavation surface shows a distinct "R" …

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Constrained Inversion Method And Application Effect Of Tem Data Of Fixed Source Loop Device, Hou Yanwei, Yao Weihua Aug 2019

Constrained Inversion Method And Application Effect Of Tem Data Of Fixed Source Loop Device, Hou Yanwei, Yao Weihua

Coal Geology & Exploration

In order to eliminate the obvious framing effect after the TEM fixed source loop device increases the receiving area, to improve the delamination ability of TEM to enhance the fine resolution for different electrical strata, the regularization inversion method with constraint is adopted. In the inversion algorithm, the Lagrange factor is adjusted adaptively by CMD regularization factor. In order to ensure the efficiency, stability and convergence of the results of the inversion process, the thickness of each layer of the inversion model is discretized according to the equal logarithmic interval, and the ill conditioned property of the matrix equation is …

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Channel Wave Advanced Detection Method Based On Kirchhoff Migration And Its Application, Zhao Yunpei, Wang Wei, Hou Xianhua Aug 2019

Channel Wave Advanced Detection Method Based On Kirchhoff Migration And Its Application, Zhao Yunpei, Wang Wei, Hou Xianhua

Coal Geology & Exploration

In order to detect the geological structures in the front of the working face 1199 in Gequan mine of Xingtai mining area, underground channel wave seismic exploration was used to conduct advanced detection, linear Radon transform was used to extract the reflection wave from the front of the roadway, parameter information of the surrounding rocks were obtained through velocity analysis in time domain, The abnormal geological bodies in the front of the roadway were imaged through Kirchhoff migration. The results indicated that there existed anomalies at 205 m and 237 m away from the geophone point G12 in the front …

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Experimental Study And Economic Evaluation Of Low Temperature Drying Treatment Of Abandoned Water-Based Drilling Fluid, Li Zhijun, Liu Xusan, Wang Bo, Zhao Wei Aug 2019

Experimental Study And Economic Evaluation Of Low Temperature Drying Treatment Of Abandoned Water-Based Drilling Fluid, Li Zhijun, Liu Xusan, Wang Bo, Zhao Wei

Coal Geology & Exploration

Abandoned water-based drilling fluids are the waste of oil drilling engineering operations. It will not only keep the cost of drilling fluid high, but also have a very adverse impact on the environment if it is directly discharged. Reusing of abandoned water-based drilling fluid after low-temperature drying treatment is one of treatment methods which is economic and conforms to the modern development trend. In this paper, the experimental study and economic evaluation of the low-temperature drying technology of polymer drilling fluid system, sulfonated drilling fluid system and Sichuan shale gas well drilling fluid system were conducted. The results show that …

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Detection Accuracy Analysis Of Tsp And Its Application In A River-Crossing Tunnel Construction, Li Junjie, Zhang Honggang, He Jianshe, Rong Xin, Li Jianqiang, Guo Jiahao Aug 2019

Detection Accuracy Analysis Of Tsp And Its Application In A River-Crossing Tunnel Construction, Li Junjie, Zhang Honggang, He Jianshe, Rong Xin, Li Jianqiang, Guo Jiahao

Coal Geology & Exploration

Aiming at the problems of TSP such as long detection time and strong experience-depending, in order to improve the accuracy and the efficiency of TSP detection, we analyzed the key factors which affect data acquisition and processing accuracy of TSP and summarized the experiences of improving the detection efficiency of TSP. In combination with the TSP advanced geological prediction work in a river-crossing tunnel for water distribution project in Qiandaohu lake, the TSP tracing prediction or GPR detection in the area where the TSP resolution decreases were carried out and the geophysical abnormal area was verified by drilling. The results …

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Occurrence Of Antimony In Magmatic Intrusive Coal Seam: A Case Study From The Wolonghu Coal Mine, Huaibei Coalfield, China, Ou Jinping, Zheng Liugen, Wei Xiangping, Liu Sikui, Li Liyuan, Liu Meng, Huang Xiaoyu Aug 2019

Occurrence Of Antimony In Magmatic Intrusive Coal Seam: A Case Study From The Wolonghu Coal Mine, Huaibei Coalfield, China, Ou Jinping, Zheng Liugen, Wei Xiangping, Liu Sikui, Li Liyuan, Liu Meng, Huang Xiaoyu

Coal Geology & Exploration

In order to investigate the influence of magmatic alteration on the occurrence characteristics of antimony in coal seam, 12 samples of magmatic magma and coal were collected from Wolonghu coal mine in Huaibei coalfield, Anhui Province, and the content of Sb was determined by atomic fluorescence spectrometry(AFS). The coal quality parameters are analyzed. The results are as follows:the coal in Wolonghu magmatic intrusion area has the characteristics of ultra-low volatile matter, medium ash content and ultra-low sulfur content. And the main forms of sulfur in coal are organic sulfur and pyrite sulfur. Under the influence of magmatic hydrothermal solution, ash …

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Study On Current State And Methods Of Marine Carbon Emissions Mrv In Chinese Shipping Sector, Weiyu Han Aug 2019

Study On Current State And Methods Of Marine Carbon Emissions Mrv In Chinese Shipping Sector, Weiyu Han

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.

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Compensation For Marine Environmental Damage From Ship-Source Pollution, Sinhyok Pak Aug 2019

Compensation For Marine Environmental Damage From Ship-Source Pollution, Sinhyok Pak

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.

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Cooperation In Maritime Search And Rescue Between Democratic People’S Republic Of Korea, The People’S Republic Of China And The Russian Federation, Kwangmyong Ri Aug 2019

Cooperation In Maritime Search And Rescue Between Democratic People’S Republic Of Korea, The People’S Republic Of China And The Russian Federation, Kwangmyong Ri

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.

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Study On The Development Of Mass Based On Safety, Qiyu Yu Aug 2019

Study On The Development Of Mass Based On Safety, Qiyu Yu

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.

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