Earth Sciences Commons^™

Effects Of Longitudinal Training Walls On Two-Dimensional Flow Structure, Sediment Transport, And Bed Aggredation Using Numerical Methods And Sediment Core Analyses In Grand River, Michigan, Sumaiya Tul Siddique

LSU Doctoral Dissertations

Longitudinal training walls (LTWs) are structures oriented parallelly with the main flow and separate the channel into two sub-channels. One channel acts as the main navigational channel and the other is considered a secondary side channel. The long-term effects of the LTWs on morphodynamics and deposition remain poorly understood. This study investigated the long-term effects of the LTWs on flow, sediment transport and long-term deposition of the Grand River using numerical approaches and sediment core analysis. The effects of LTWs on 2D flow dynamics and sediment transport were investigated by using numerical approaches. The long-term deposition under the influence of …

Revealing Grounding Zone And Subglacial Processes At Cosgrove Ice Shelf: Seafloor Analogs For The Modern Antarctic Ice Sheet, Rosemary E. Burkhalter-Castro

USF Tampa Graduate Theses and Dissertations

The future loss of ice in West Antarctica is one of the biggest uncertainties in projections of global sea level rise. The West Antarctic Ice Sheet (WAIS), home to Cosgrove Ice Shelf (CIS), contains enough ice to raise global sea level by more than three meters if it collapsed completely. Accurately predicting how much sea level change may occur from a future collapse of WAIS is of particular interest to low-lying, heavily populated coastal areas such as Florida. For this reason, it is important to understand the processes underpinning rapid changes and retreat at marine-terminating glaciers in the Amundsen Sea. …

Modern Lakeshore Processes And Historic Lake And Glacial Changes In Taylor Valley, Antarctica, Michael Stanley Stone

LSU Doctoral Dissertations

Taylor Valley, which opens to the Ross Sea, is one of several ice-free valleys comprising the McMurdo Dry Valleys, Antarctica. The valley is home to several close-basin, perennially ice-covered lakes, whose lake levels largely reflect a balance between meltwater inputs and lake ice ablation; both being driven by climate. A dynamic environment exists where the lake ice covers meet the lakeshore, with the ice grounding to the substrate throughout the cold and dark of winter, and melting to form a perimeter of thin-to-no ice around the lake during the summer. These marginal freeze-thaw regions are known as moats. Here, physical, …

Evaluating Indoor Air Quality In Residential Environments: A Study Of Pm2.5 And Co2 Dynamics Using Low-Cost Sensors, Kabir Bahadur Shah, Dylan Kim, Sai Deepak Pinakana, Mkhitar A. Hobosyan, Armando Montes, Amit U. Raysoni

School of Earth, Environmental, & Marine Sciences Faculty Publications

Indoor air quality (IAQ) poses a significant public health concern, and exposures to high levels of fine particulate matter (PM2.5) and carbon dioxide (CO2) could have detrimental health impacts. This study focused on assessing the indoor air pollutants in a residential house located in the town of Mission, Hidalgo County, South Texas, USA. The PM2.5 and CO2 were monitored indoors: the kitchen and the bedroom. This investigation also aimed to elucidate the effects of household activities such as cooking and human occupancy on these pollutants. Low-cost sensors (LCSs) from TSI AirAssure™ were used in this study. They were deployed within …

A Dynamic Damage Rate-Based Constitutive Model For Rock Damage, Meng Xiangzhen, Zhang Huimei, Li Yugen, Yuan Chao, Chen Shiguan

Coal Geology & Exploration

Objective A constitutive model is identified as the most effective method for describing the deformations and failure characteristics of rocks and characterizing their mechanical behavior. Developing the equation and constitutive model for the dynamic damage evolution of rocks based on changes in their damage rates under loading is an important part of rock mechanics. Methods To further investigate the whole process of rock deformations and failure under loading, rocks were divided into the damaged and undamaged parts via abstraction, with the latter bearing effective stress and the former bearing residual stress. This study established the equation and constitutive model based …

Mechanisms And Control Of Rock Bursts In Goaf-Side Roadways Under The Condition Of Thick And Hard Roofs In The Xinjie Mining Area, Inner Mongolia, Liu Wenchao, Zhao Yixin, Guo Jihong

Coal Geology & Exploration

Objective and Methods Rock bursts in mining roadways in deep coal mines under the condition of thick and hard roofs severely threaten the safe coal mining of the mining face. To meet this threat, this study, focusing on the No.3^-1103 mining face auxiliary transport roadway, a goaf-side roadway, in a typical deep mine of the Xinjie mining area, Inner Mongolia, analyzed the external dominant factors and internal driving sources for frequent rock bursts in the goaf-side roadway. Assuming the mechanical characteristics of the rock beam-foundation system, this study constructed mechanical models under loading before roof fracturing based on …

Effect Of Cadmium-Free Filler Metal On Mechanical Properties And Microstructure Of Pdc Cutters, Zhang Suhui, Yao Ningping, Liu Qingxiu, Liu Huan, Wang Dechuan

Coal Geology & Exploration

Objective PDC bits are critical components of geological support equipment and play a vital role in advancing technology and improving efficiency in the coal industry. Currently, PDC bits are brazed using silver filler metals containing cadmium, a toxic and polluting element. This study introduces the use of environmentally friendly, cadmium-free filler metals for brazing PDC bits. Methods The study investigates the wetting mechanism between brazing filler metals and base materials, utilizing Ag-Cu-Zn series brazing filler metals containing high silver and Sn, Mn and Ni, and only Ni for flame brazing of PDC cutters and steel. The shear strength of different …

Rock Burst Hazard Evaluation Of Coal Mining Face Based On A Gaussian Mixture Model, Cui Feng, Li Yifei, Jia Chong, Lu Changliang, He Shifeng, Zhang Suilin, Tian Mengqi

Coal Geology & Exploration

Objective Deep insights into the probabilistic information contained in the energy distribution of acoustic emission (AE) or microseismic events are significant for the rock burst hazard evaluation of coal mining face. Methods This study investigated No.40111 mining face of the No.4 coal seam at the Dafosi Coal Mine in Shaanxi Province. Using physical simulation experiments with similar materials, theoretical analysis, and on-site monitoring, this study investigated the evolutionary patterns of AE monitoring data during coal mining and illustrated the physical meaning of fluctuations in the probability distribution of AE energy. Accordingly, this study proposed an index model for the rock …

Advances In Research On The Evolution Of Trans-Scale Discontinuous Structures During The Creeps Of Strongly Disturbed Coals, Zhang Liang, Wang Laigui, Ren Ting, Li Xiangchun, Gao Ke, Li Haitao, Zhao Shankun

Coal Geology & Exploration

Objective and Methods Disasters associated with surrounding rocks in roadways, such as time-dependent deformation failure and creep-induced rock bursts, severely threaten deep mines in China. These disasters, coupled with the impacts of deep mining and structural changes, render it urgent to explore the evolutionary patterns of trans-scale discontinuous structures during the creeps of strongly disturbed coals. This study systematically reviews the scale effects of coals' mechanical properties, the discontinuous structures and multi-physics field effects of coals, and the long-term stability, creep evolutionary patterns, and mechanical models of coals. It highlights the close correlation between discontinuous structures (including their fractures and …

Sedimentary Environments, Mechanical Properties, And Rock Burst Risk Identification Of Overburden In Deep Mines, Qiao Wei, Cheng Xianggang, Dou Linming, He Hu, Meng Xiangsheng, Ren Yangyang, Xiao Chong, Cai Jin

Coal Geology & Exploration

Objective Disaster risk identification and prediction serve as a prerequisite for disaster control. An engineering geological environment is identified as the fundamental condition inducing dynamic disasters like rock bursts in mines. Exploring the sedimentary genetic mechanisms of engineering geological environments holds great significance for predicting rock burst risks. Methods With the Gaojiapu Coal Mine in the Binchang mining area, Shaanxi Province, as a case study, this study analyzed the engineering geological characteristics of rock masses under different sedimentary microfacies. Furthermore, it explored the deformation and failure characteristics of rocks in different sedimentary environments, along with the energy release patterns of …

An Experimental Study Of The Evolutionary Patterns Of Mechanical Properties Of Coals Under Multiple Mining Disturbances, Ouyang Zhenhua, Liu Yang, Li Chunlei, Shi Qingwen, Li Wenshuai, Yi Haiyang, Qin Hongyan, Zhang Ningbo

Coal Geology & Exploration

Objective In the mining process of coal mines, the cyclic loading and unloading effects caused by multiple mining disturbances can alter the mechanical properties of coals, serving as a significant cause of rock bursts. Revealing the response characteristics of crucial mechanical parameters and the damage mechanisms of coals can provide a basis for discriminating the impact-induced instability state, holding great significance for enhancing disaster prediction capabilities. Methods Quasi-static uniaxial cyclic loading and unloading experiments and the dynamic impact loading experiments on large-size coal-like specimens were combined to accurately capture the stress, strain, and acoustic emission responses during the experiments, thoroughly …

Evolutionary Characteristics Of Microcracks In Rocks Under Weak Dynamic Disturbance And Disaster Prevention And Control, Jiang Mingwei, Liang Yuntao, Feng Wenbin, Li Haitao, Zhou Rui, Guo Baolong, Liu Yang, Ma Ju

Coal Geology & Exploration

Objective High stress with superimposed weak dynamic disturbance serves as a critical factor including rock bursts. However, the microcrack propagation characteristics and energy dissipation pattern of rocks under different disturbance amplitude, frequencies, and unloading ranges remain unclear, leading to a lack of technical support for rock burst prevention and control.Methods Based on the true triaxial unloading dynamic disturbance tests, this study analyzed the instability failure patterns of deep surrounding rocks under different disturbance amplitude (5, 10 MPa), frequencies (4, 10 Hz), and triaxial stress unloading (0, 12 MPa). Moreover, this study examined the characteristics of microcracks in rocks using …

Table Of Contents, The Editors

Coal Geology & Exploration

No abstract provided.

Rock Bursts Induced By Thick-Hard Roof With Compound Key Strata: Mechanisms And Technical Modes For Prevention, Zheng Kaige, Yuan Liang, Zhang Pingsong, Wang Lintao

Coal Geology & Exploration

Objective Thick-hard roofs serve as the key factor inducing disasters such as rock bursts and mining-induced earthquakes in coal mines. These disasters are especially serious in the case of coal seam roofs with compound key strata. Hence, there is an urgent need to reveal the mechanisms behind the rock bursts induced by thick-hard roofs with compound key strata and to develop technical modes for the prevention and control of these rock bursts. Methods Using methods including physical simulation experiments on similar materials and mechanical analysis, this study developed methods for identifying roofs with compound key strata and for non-synergistic breaking …

Mechanisms Behind Mine Earthquake-Induced Dynamic Instability Of Thick Top Coals In High-Stresses Roadways, Zhou Kunyou, Dou Linming, Cao Anye, Ma Yankun, Kan Jiliang, Li Jiazhuo, Ma Xiaotao

Coal Geology & Exploration

Objective Thick top coals are common in roadways excavated along the bottom of thick coal seams. Mine earthquakes along the mining face can exert dynamic loading on thick top coals in roadways, prone to induce the dynamic instability of thick top coals and even roof fall-rock burst compound disasters. Therefore, there is an urgent need to explore the mechanisms behind the dynamic instability of thick top coals in roadways under dynamic loading induced by mine earthquakes. Methods This study investigated a roadway of deep thick top coals in the Binchang mining area, Shaanxi. Specifically, this study analyzed the dynamic instability …

Fracturing Characteristics Of Significantly Thick Overburden Inducing Mine Earthquakes And The Stress-Triggering Mechanisms Of The Mine Earthquakes, Dou Linming, Cao Anye, Yang Yao, He Hu, Yang Yaoxin, Bai Xianxi, Gu Qianyue, Li Songhui, Fu Xiangchao, Gu Yingshi, Wu Zhen, Zhang Di

Coal Geology & Exploration

Objective Frequent mine earthquakes that cause surface seismaesthesia, induced by the fracturing of significantly thick overburden in deep coal mining, are identified as the most severe challenge to the efficient production of mining areas. There is an urgent need to overcome the current difficulty caused by mine earthquakes induced by significantly thick overburden, which feature high frequency and challenging prevention and control. Methods Using such mine earthquakes occurring in a certain fully mechanized mining face adjacent to goaves in the Khujirt mining area in Ordos, Inner Mongolia Autonomous Region, as an example, this study (1) analyzed the evolutionary patterns of …

Mechanism Of Thrust Fault Slip Under The Disturbance Of Stress Waves Induced By Coal Mining, Zhang Ningbo, Xu Qianhai, Ouyang Zhenhua, Li Yizhe, Shi Qingwen, Qin Hongyan, Yi Haiyang

Coal Geology & Exploration

Objective The seismic sources, such as roof collapse and artificial blasting, in coal mining may induce stress waves, which will cause the surrounding faults lose its stability and thus cause the dynamic disasters such as rockbursts etc. Methods The propagation law of stress waves in the fracture structure and the evolution characteristics of friction energy under the action of stress waves were studied through dynamic photoelastic experiment, numerical simulation and theoretical analysis based on the thrust fault F16 in Henan Yima mining area. Meanwhile, the disturbance law of the location of seismic source and energy to the slip of thrust …

Influencing Analysis Of Bedding Plane Location On The Dynamic Failure Characteristics Of Coal-Rock Combinations, Zheng Jianwei, Zhang Xiufeng, Ju Wenjun, Wang Cunwen, Han Yueyong, Li Guoying, Chen Yang, Li Haitao, Hao Jinwei, Liu Biao

Coal Geology & Exploration

Objective The bedding plane location significantly impacts the dynamic failure processes and mechanical properties of coal-rock composites, but the specific influence patterns remain unclear. Methods Dynamic mechanical tests were conducted on coal-rock composite specimens with bedding planes located at the top, middle, and bottom using the split Hopkinson pressure bar (SHPB). The investigation focused on the dynamic stress-strain behavior, failure process, energy distribution, and fragmentation characteristics under impact loading conditions. Results and Conclusions The findings indicate that: (1) The dynamic stress-strain behavior of coal-rock composites can be segmented into five distinct stages: near-linear stage, nonlinear dynamic stress-strain stage, elastic modulus …

Exploring The Evolutionary Patterns Of Stress Field In Coal Seams During Water Drainage In Overburden Confined Aquifers Based On Charge Monitoring, Wang Gang, Yu Xiaojie, Wang Aiwen, Xiao Xiaochun, Wang Yong, Ding Xin, Wang Weibin, Xu Zengjun, Du Lulu

Coal Geology & Exploration

Objective Deep coal mining areas in regions such as Inner Mongolia, Shaanxi, Shandong, and Gansu in China feature intricate hydrogeological conditions, which lead to substantial water drainage from roofs and increasingly prominent rock bursts induced by water drainage in overburden confined aquifers. This study investigated the evolutionary patterns of the stress field in coal seams during the water drainage of overburden confined aquifers. Methods By combining the laboratory charge induction experiments of coals under graded loading with charge monitoring pre- and post-water drainage from a roof in a coal mine, this study systematically examined the variations of induced charge in …

Spatiotemporal Evolutionary Characteristics Of Asymmetric Stress Transfer In Overburden Of Steeply Dipping Coal Seams, Zhu Kaipeng, Li Zhilin, Luo Shenghu, Xie Panshi, Fan Juan, Wang Tong, Tian Chengyang, Yan Zhuangzhuang

Coal Geology & Exploration

Objective The key to the safe and efficient mining of steeply dipping coal seams is the effective control of the stability of surrounding rocks, while the effective control is underpinned by identifying and revealing the spatiotemporal evolutionary characteristics of the stress transfer path of the overburden. Methods This study investigated mining face 25221 of a coal mine in Xinjiang through field measurement, physical simulations using similar materials, and numerical computation. This study determined the rock pressure behavior of the mining face, along with the deformation and failure patterns of the overburden, through a comprehensive analysis. Accordingly, it established stress characteristic …

Evolutionary Pattern And Control Technology Of Mine Pressure When Mining Face For Coal Pillars In Main Roadways Passing Through Abandoned Roadways, Li Zhenhua, Ren Ziyuan, Du Feng, Ren Hao, Wang Wenqiang

Coal Geology & Exploration

Objective With the adjustment of the mining face layout in mines, the overburden roof of the mining face for coal pillar recovery is frequently difficult to control when the mining face passes through abandoned roadways. Methods To address this challenge, this study investigated the coal pillar mining face outside the No.2 panel in the Zhaogu No.2 Coal Mine in Henan Province, which passes through abandoned roadways. Using methods like theoretical analysis, numerical simulation, and in-situ tests, this study examined the composite structure of the mining face and the broken overburden of abandoned roadways, followed by simulation of the full-cycle evolutionary …

Spatial Surveying Characteristics And Reconstruction Method Of Millimetre Wave Radar In Complex Environment Of Coal Mine Roadway, Xue Xusheng, Yang Xingyun, Yue Jianing, Wang Chuanwei, Mao Qinghua, Ma Hongwei, Wang Rongquan

Coal Geology & Exploration

Objective Underground spatial surveying of coal mine is an important part of transparent geological modelling for coal mine. However, the complex environment of coal mine roadway, incomplete information acquisition, insufficient accuracy of sensed data and other difficulties need to be urgently solved. Methods First, the signal characteristics of millimeter wave radar under the complex environmental factors such as dust, water mist, surrounding rock structure, etc. were studied in depth, the millimeter wave signal attenuation model was established for the surrounding rock of coal mine roadway, and the influence mechanism of complex environmental factors for millimeter wave radar was comparatively analyzed. …

Advances In Research On Stratigraphic Characteristic Parameter Modeling And Safety Early Warning For Deep Geological Drilling Processes, Yang Yulong, Cao Weihua, Gan Chao, Li Yupeng, Wu Min

Coal Geology & Exploration

Significance As the new round of national exploration & development planning continues, resource exploration is advancing toward the deep Earth. However, deep strata exhibit diverse rock types, which complicate the measurement of rock mechanical parameters. Furthermore, the harsh environments of these strata, characterized by high temperatures, high pressures, and high in-situ stress, are prone to induce downhole accidents like drilling tool failure, wellbore collapse, loss of circulation, and well kicks, posing challenges to geological drilling. Advances Aiming at the perception and modeling of complex geological environments, this study reviews the existing studies on the modeling of stratigraphic characteristic parameters from …

Subsoil Testing Required To Detect The Rundown Of Soil Potassium To Deficient Levels For Wheat Production On Loam-Textured Soils, Craig Scanlan, Richard Bell, Miaomiao Cheng, Tim Boyes

Grain and Other Field Crops Research Articles

Context

Long-term negative potassium (K) balances in crop production have depleted soil K levels in Western Australia (WA). Previous research has focussed on sand-textured soils, but recently, monitoring of crops grown on loam-textured soils has shown deficient or marginal shoot K concentrations where Colwell K 0–10 cm is above current critical levels.

Aims

The aims were to examine whether grain yield responses to fertiliser K can be detected on loam-textured soils and if soil test calibration curves can be identified for these soils.

Methods

Eight field trials were conducted with wheat on loam-textured soils. The same experimental design was used …

Effect Of Crop Age On Seed Yield Of Arachis Pintoi At Two Sites In Costa Rica, Pedro J. Argel, Alfredo Valerio

IGC Proceedings (1977-2023)

Arachis pintoi is a forage legume well adapted to the humid tropics of Costa Rica. Seed production studies were carried out at two contrasting localities within the country, Gulipiles (very humid tropics) and San Isidro (seasonal evergreen tropical forest). The accessions CIAT 18748, 18744 and 17434 cv. Amarillo of A. pinloi were vegetatively planted at both sites. Seed yields were measured at 8, 12, 16 and 20 months post- planting inGulipiles, and at·8, 16 and 20 months in San Isidro. Mean seed yields among accessions were similar in San Isidro but significantly different in Gulipiles; however, the contrary occurred in …

Efficient Nitrogen Fertilization In Grass Seed Crops With Regard To Soil Mineral Nitrogen Content And Analyzing Grass Tillers In Spring, W Schoberlein, H J. Wahl

IGC Proceedings (1977-2023)

When applying the Nmln method in grass seed crops analogously lo that in cereal crops we proceed from the experience that for a mean level of mineralisation, the sum total of soil-borne Nm1n available to plants at the beginning of the growth period and Nd Input in the form of fertiliser will provide sufficient N to the crop. The total quantity of mineral soil-borne N and fertiliser N is considered as the nominal value. The required N input can be derived from the difference between nominal value and mineral soil-borne N (Nd = nominal value• Nrnin>· For Dactylis glomerata …

Effects Of Aneuploidy On Seed Production In Autopolyploid Forage Crops, A Elgersma

IGC Proceedings (1977-2023)

Between the selection of a population and its commercial use, several generations of multiplication are necessary. The essential feature in variety maintenance is that no genetic changes occur during multiplication. In seed-propagated species, however, during each multiplication cycle natural selection takes place at ihe gamete, zygote, seed and plant level. In induced autopolyploids high frequencies of aneuploids can occur. Aneuploidy not only affects the seed yield level, but also the selection processes that occur during multiplication. It may cause genetic shift and affect variety stability. Species differ in their tolerance to aneuploids. It is not possible to eliminate aneuploidy by …

Effects Of Ratooning And Protection From Diseases And Birds On Seed Production In Guinea Grass, Okoro Oji, F N. Madubuike, F.O C. Ezedinma

IGC Proceedings (1977-2023)

Effects of ratooning and protection from diseases and birds on seed production in guinea grass (Pannicum maximum L.) were assessed in a study from October 1986 to April 1987. Treatments included ratooning and mancozeb application with or without protection from birds (netting). Highest yield occurred with combined netting and mancozeb application. Mancozeb sp,aying without netting gave lower seed yield than netting without fungicide spraying. Seed yield, which generally decreased with ratooning, was lowest among unnetted and unsprayed crops. Prom anthesis to seed maturation lasted, on average, 9 days, and seeds borne on the upper part of the panicle matured …

Potential For Improved Honey Bee Pollination Efficiency From Easy-To-Trip Lucerne, L R. Teuber, E E. Knapp

IGC Proceedings (1977-2023)

The principal pollinator of lucerne (Medicago sativa L.) in California, USA is the honey bee (Apis mellifera L.). However, honey bees are notoriously inefficient pollinators of lucerne because they learn to avoid tripping the floret. Easy-to-trip lucerne florets could reduce this problem. These studies were designed to determine the inheritance of ease of tripping and assess the effect of ease of tripping on the rate of outcrossing. Both additive and digenic variance for ease of tripping were significant, resulting in a heritability of 34.0:1:16.2%. Ease of tripping had no influence on outcrossing rate, which was estimated to average …

Effect Of Final Cutting For Fodder On Seed Yield And Seed Quality In Berseem, S L. Saini, R K. Chowdhury

IGC Proceedings (1977-2023)

The study was conducted to determine the appropriate time of final culling (closing) for fodder to optimise the seed yield and seed quality in berseem (Trifolium alexandrinum L.). Based on 2 years' experimentation, the maximum seed yield was obtained when the final cut for fodder was taken in mid•March and the crop was then closed for seed. Seed yield was reduced drastically when the final cut was delayed to late March•April. The seed quality parameters of standard germination, seed weight and vigour index were also reduced when the final cut for fodder was delayed to late March•early April. Based …