检索结果-南通市图书馆

Journal of Rock Mechanics and Geotechnical Engineering 2025年第1期17卷 432-452页

作者： Nilanjana Banik Rajib Sarkar department of Civil Engineering Indian Institute of Technology(Indian School of Mines)DhanbadDhanbad826004India

The microbial-induced calcite precipitation(MICP)technique has been developed as a sustainable methodology for the improvement of the engineering characteristics of sandy ***,the efficiency of MICP-treated sand has not been well established in the literature considering cyclic loading under undrained ***,the efficacy of different bacterial strains in enhancing the cyclic properties of MICP-treated sand has not been sufficiently ***,the effect of wetting-drying(WD)cycles on the cyclic characteristics of MICP-treated sand is not readily available,which may contribute to the limited adoption of MICP treatment in field *** this study,strain-controlled consolidated undrained(CU)cyclic triaxial testing was conducted to evaluate the effects of MICP treatment on standard Ennore sand from India with two bacterial strains:Sporosarcina pasteurii and Bacillus *** treatment durations of 7 d and 14 d were considered,with an interval of 12 h between *** cyclic characteristics,such as the shear modulus and damping ratio,of the MICP-treated sand with the different bacterial strains have been estimated and ***,the effect of WD cycles on the cyclic characteristics of MICP-treated sand has been evaluated considering 5–15 cycles and aging of samples up to three *** findings of this study may be helpful in assessing the cyclic characteristics of MICP-treated sand,considering the influence of different bacterial strains,treatment duration,and WD cycles.

关键词： Bio-cemented sand Microbial-induced calcite precipitation(MICP)treatment Consolidated undrained(CU)cyclic triaxial testing Cyclic characteristics Wetting-drying(WD)cycles

Paleomapping:Creating testable visual hypotheses of ancient worlds

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Palaeogeography 2025年第01期14卷 91-104页

作者： Holger Petermann Annaka M.Clement Patrick M.Sullivan Hannah M.Bonner James W.Hagadorn department of Earth and Space Sciences Denver Museum of Nature & Science Colorado School of mines Department of Geology and Geologic Engineering Division of Water Quality Utah Department of Environmental Quality

The story of the Earth's changing landscapes is often told through paleogeographic maps. These images are some of the most accessible and widely used illustrations in the Earth sciences. However, no formal procedure for the creation of photorealistic paleomaps(i.e., paleosatellite images) exists. Using an example from the Late Jurassic of the Rocky Mountain region, we present a method for making paleoenvironmental and paleosatellite maps that is scalable, reproducible, testable, and incorporates peer review. The process includes a literature review followed by data-visualization, paleoenvironmental interpretation, peer-review,iterative revisions, and the creation of a false contour map and color gradient used to render a paleosatellite image. Paleosatellite images are photorealistic versions of paleoenvironmental maps that incorporate global climatic and tectonic information as well as principles of actualism; they can be made through comparison to analogous modern landscapes. An important component of this process is that the data maps that ground this paleomapping process allow evaluation of where paleoenvironmental interpretations are wellsupported by outcrop and subsurface data, and where such visualization is highly interpretive-often because of lack of available rocks or studies in a given area. As such, our paleoenvironmental maps and paleosatellite images are testable pictorial hypotheses. By outlining a procedure that produces referenced,data-rich, and visually realistic maps, we hope to demystify the paleoenvironmental map-making process and improve accessibility of paleomaps for the broader geoscience community. Where resources and complementary data are available, such maps also have potential for georeferencing and integration with larger continent-scale paleogeographic maps.

关键词： Ancient landscapes Cartography Paleogeography Paleoenvironments Jurassic

Can laser irradiation improve the strength of weak rock mass?

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2025年第1期17卷 139-153页

作者： Xiaowei Feng Peng Huang Valter Carvelli Gongshun Lin Chuankai Zhu Fengzhen He School of mines China University of Mining and TechnologyXuzhou221116China department of Architecture Built Environment and Construction EngineeringPolitecnico di MilanoMilan20133Italy

Controllable rock cracking technology is crucial for the exploration and exploitation of deep underground *** existing studies have been dedicated to the laser-assisted rock-weakening *** has been proved that laser irradiation can improve drilling and blasting efficiency when combined with mechanical rock fracturing methods,which are irrelevant for borehole *** improve the latter,this study used laser ablation for borehole *** high-power laser was applied to typical rock samples(sandstone,mudstone and coal)in both dry and saturated ***-technique observations and measurements were used to fully understand the peculiar modifications of the specimens under laser treatment,*** loading,acoustic emission(AE)monitoring,digital image correlation(DIC)strain field evaluation,infrared thermography(IRT)monitoring and X-ray computed tomography(CT)*** results showed that,in addition to the effects already demonstrated,laser irradiation can improve the strength of the soft rock,especially in the saturated *** process involved a complicated phase change including melting and evaporation of the matrix under high-temperature and high-pressure to form a glassy high strength silicate *** process is similar to the reaction between molten lava and water,or the impact of an asteroid on the *** by the results,a conceptual path for a new borehole stabilization technology using laser ablation was outlined.

关键词： Laser irradiation Rock Cracking Ablation Borehole stability Mechanical characteristics

Multi-frequency formation mechanism and modulation strategy of self-priming enhanced submerged pulsed waterjet

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2025年第2期35卷 175-189页

作者： Haojie Jia Yanwei Liu Weiqin Zuo Hongkai Han Ping Chang Mohammad Waqar Ali Asad Guozhong Hu Jian Miao Hani SMitri College of Safety Science and Engineering Henan Polytechnic UniversityJiaozuo 454003China Henan International Joint Laboratory of Coal Mine Safety and Occupational Hazards Prevention and Control Jiaozuo 454003China Zhengzhou Institute for Advanced Research of Henan Polytechnic University Zhengzhou 451464China WA School of mines:Minerals Energy and Chemical EngineeringCurtin UniversityKalgoorlie WA 6430Australia School of mines China University of Mining and TechnologyXuzhou 221116China School of Intelligent Engineering Shandong Management UniversityJinan 250357China department of Mining and Materials Engineering McGill UniversityMontreal H3A0E8Canada

Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.

关键词： Multi-frequency Modulation Self-priming Submerged waterjet Cavitation

Geochemistry of Neoproterozoic metavolcanic rocks from the Tahtai Logomiti area,Tigrai,Northern Ethiopia:Implication for petrogenesis and tectonic settings

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2025年第1期44卷 128-144页

作者： Azeb Gebremicale Mulugeta Alene Teklay Gidey School of Earth Sciences Mekelle UniversityP.O.Box:231MekelleEthiopia School of Earth Sciences Addis Ababa UniversityP.O.Box:1176Addis AbabaEthiopia department of Earth Environmental and Planetary SciencesCase Western Reserve UniversityClevelandOHUSA Faculty of mines Aksum UniversityP.O.Box:1010AksumEthiopia

The Tahtai Logomiti area is characterized by metavolcanic and metavolcaniclastic interbedded with clastic and carbonate metasedimentary rocks of Neoproterozoic *** geological,petrographic,major,and trace elements data were used to evaluate the metamorphism,petrogenesis,and paleo-tectonic setting of the *** field and petrographic observation indicate that the area has undergone greenschist facies *** on mineralogy and geochemical attributes,these metavolcanic rocks are classified as basalt,basaltic-andesite,andesite,and *** moderate degrees of light rare earth element(LREE)enrichment,flat heavy rare earth element(HREE)pattern,and low Nb/Y ratio,represent shallow mantle *** addition to that,the TiO_(2)/Yb ***/Yb diagram,high(La/Yb)N ratio(>3.44),indicates shallow melting and depleted magma ***,the high ratios of(Th/Ta)>3.8,(La/Ta)>38,and low ratios of(Th/La)<1,(Nb/La)<1,and high Pb content would indicate crustal contamination of the *** discrimination diagram and trace element ratios(Nb/Y,La/Sc,La/Y,and La/Th)indicate that the metavolcanic rocks have a calc-alkaline *** addition,the ZrNb-Y and Th-Hf-Ta plots show that the rocks formed under a volcanic-arc *** general petrological and geochemical characteristics of the Tahtai Logomiti metavolcanic rocks suggest that the area is associated with subduction-related arc accretion of the Arabian Nubian Shield.

关键词： Deformation Metamorphism Foliation Calc-alkaline Neoproterozoic Arabian Nubian Shield

Autocyclic switching processes and architecture of lobes in river-dominated lacustrine deltas

在线全文

学校读者我要写书评

暂无评论

Journal of Palaeogeography 2025年第1期14卷 126-140页

作者： Zhen-Hua Xu Sheng-He Wu Piret Plink-Bj?rklund Tao Zhang Da-Li Yue Qi-Hao Qian Qing Li Wen-Jie Feng National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum (Beijing) College of Geosciences China University of Petroleum (Beijing) department of Geology and Geological Engineering Colorado School of Mines Gas Production Plant 2 PetroChina Changqing Oilfield Company PetroChina Research Institute of Petroleum Exploration and Development College of Geosciences Yangtze University

River-dominated lacustrine deltas typically consist of multiple lobes due to autogenic lobe switching that occurs over short time scales. However, the switching patterns of multiple lobes in these deltas remain poorly understood, and the architectural features attributed to lobe switching are also lacking. By integrating Delft3D simulations, flume experiments, and modern deposit analysis, we proposed that autogenic lobe switching follows a cyclic pattern. Autocyclicity begins with the formation of an offshore lobe and concludes after a series of longshore lobe growth events, marked by longshore avulsions occurring along the sides of offshore distributary *** avulsions follow a sequence that usually occurs earlier distally than proximally and subsequently occurs on one longshore side and then on the other side. Each lobe begins with rapid growth, which gradually slows and then stops once a channel avulsion is influenced by the backwater effect that triggers lobe switching. Three signals indicate lobe switching: a decrease in progradation rate, foreset slope steepening coupled with topset slope gentling, and the deposition of mud-dominated sediments. The number of autocyclic events never exceeds *** first two autocyclicities contribute to more than 55% of delta length and 70% of delta area. The lobes are separated by 1-6 stages of mud-dominated accretion beds that exhibit a downstream-inclined shape and convexup or lateral overlapping pattern. This study conducts a coupled growth-geometric assessment to establish an architectural pattern for river-dominated lacustrine deltas. This architectural pattern offers valuable insights into predicting sandy lobe distribution in river-dominated lacustrine delta reservoirs, and the architecture of muddy accretion beds aids in predicting the rule of oil-water movement and distribution of remaining oil.

关键词： Autocyclic lobe switching River-dominated lacustrine delta Architecture Avulsion sequence Backwater effect

Sesam, toward a Mature Magmatic Arc Sourced from Tholeiitic Volcanisms and Calc-Alkaline Volcanoplutonism within Kedougou-Kenieba Inlier, South-East Senegal/West Africa

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Geoscience and Environment Protection 2025年第1期13卷 331-386页

作者： Mame Codou Ndiaye Mamadou Ndiaye Papa Malick Ngom Mababa Diagne Andrea Moscariello Antoine De Haller National Superior School of mines et and Geology Cheikh Anta Diop University Dakar Senegal Geology department Faculty of Sciences and Technics Cheikh Anta Diop University Dakar Senegal department of Earth Sciences and Environment Amadou Makhtar Mbow University Diamniadio Senegal department of Earth Sciences and Environment University of Genova Genova Switzerland

The Paleoproterozoic terrains of Kedougou Inlier have an overall architecture formed of greenstones and sedimentary basins. Most of the work done on these Birimian formations has focused on either belts or basins, or even briefly on both, but more rarely on the transition zones between belts and Paleoproterozoic basins. Our study focuses on the lithostructural framework of the Mako-Diale transition zone located within the Kedougou-Kenieba Inlier. Its objective is to redefine the existing architecture. Geophysical, petrographic, structural and geochemical results from lithostructural domains allowed to building a new architecture based on three major lithostructural domains evolving into tectonomagmatic complexes associated with three shear zones corresponding to Western shear-contact (CiscoW) represented by Sabodala sinistral mylonitic shear (SSZ), to Median sinistral ductile then brittle shear-contact (CiscoM) and to Eastern dextral brittle-ductile shear-contact (CiscoE) corresponding to the Main transcurrent shear (MTZ). Tectonomagmatic complexes are represented by Maco oceanic crust, Sesam arc and Diale back-arc basin. The opening of Diale basin is related to CiscoM. Its closure set along the Faleme shear-contact (CiscoF) located beyong CiscoE. The tectonic evolution of the Eburnian orogeny within Kedougou-Kenieba inlier highlights four (4) deformations phases: CiscoW, CiscoM, CiscoE and CiscoF respectively running for D1, D2, D3 et D4. Such CiscoW along Sabodala, Sofia deposits and CiscoE along Massawa deposit, CiscoM and CiscoF stand as potential host structures for futures Kedougou inlier gold deposits. Furthermore, large plutonic masses within Mako-Diale transition zone belong all to three (3) distinct magmatic sources: Koulountou granodiorite, Koulountou and Tinkoto granites are sourced from high-K mafic rocks;Tiguida granite and Diabba granodiorite from low-K mafic rocks, while Dioudioukounkou granite belongs to tonalite source. The Sesam arc is located alo

关键词： Magmatism Tholeiitic Calc-Alkaline Garnet-Granite Sesam-Arc

Investigation of factors influencing roof stability at a Western *** coal mine

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2019年第1期29卷 139-143页

作者： Meriel Young Gabriel Walton Elizabeth Holley department.Geology&Geol.Engineering Colorado School of Mines department Mining Engineering Colorado School of Mines

The coal mine roof rating(CMRR) was developed to bridge the gap between geological variation in underground coal mines and engineering design. The CMRR accounts for the compressive strength of the immediate roof, the shear strength and intensity of any discontinuities present, and the moisture sensitivity of the immediate roof. The CMRR has been widely used and validated in Eastern US coal mines, but it has seen limited application in the Western US. This study focuses on roof behavior at a Western coal mine(Mine A). Mine A shows significant lateral geological variation, along with localized faulting and a laterally extensive sandstone channel network. The CMRR is not used to predict roof instability at the mine. It is, therefore, hypothesized that there are other factors that are correlated with roof instability in underground coal mines that could potentially also be considered in conjunction with the *** hypothesis was tested by collecting 30 CMRR measurements at Mine A. At each measurement location, a binary record of the roof condition(stable or unstable) was made, and other parameters such as depth of cover, presence of faulting, and sandstone channels were also recorded. ANOVA tests showed that the CMRR values and the roof conditions were not strongly correlated, indicating that the CMRR input criteria are not fully predictive of roof stability at this mine. The CMRR values showed statistically significant correlations(p less than 0.05) with faulting as well as with location at an intersection. For areas that had previously experienced roof fall but were currently stable, faulting was correlated with roof condition(p less than 0.05) only when the condition was classified as unstable.

关键词： Coal mine roof stability CMRR Western U.S.coal Case study

Propagation, reflection, and transmission of SH-waves in slightly compressible, finitely deformed elastic media

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2015年第8期36卷 1045-1056页

作者： M.CHATTERJEE A.CHATTOPADHYAY department of Applied Mathematics Indian School of Mines

The propagation, reflection, and transmission of SH waves in slightly com- pressible, finitely deformed elastic media are considered in this paper. The dispersion relation for SH-wave propagation in slightly compressible, finitely deformed layer over- lying a slightly compressible, finitely deformed half-space is derived. The present paper Mso deals with the reflection and refraction （transmission） phenomena due to the SH wave incident at the plane interface between two distinct slightly compressible, finitely deformed elastic media. The closed form expressions for the amplitude ratios of reflection and refraction coefficients of the reflected and refracted SH waves are obtained from suit- able boundary conditions. For the numerical discussions, we consider the Neo-Hookean form of a strain energy function. The phase speed curves, the variations of reflection, and transmission coefficients with the angle of incidence, and the plots of the slowness sections are presented by means of graphs.

关键词： slightly compressible SH wave propagation inhomogeneity reflection,transmission slowness section

Influence of heat treatment on the structural and optical properties of SrGd_2O_4:Eu^(3+) phosphor

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2015年第10期33卷 1040-1050页

作者： Jyoti Singh Pankaj Kr.Baitha J.Manam department of Applied Physics Indian School of Mines

Novel red emitting Eu3＋ doped SrGd2O4 phosphors were synthesized by homogeneous precipitation method followed by a subsequent combustion process at various temperatures. A systematic study on the consequent structural evolution and optical properties were investigated as a function of various processing temperatures. With the enhancement of processing temperature, SrGd2O4 phosphor showed a gradual transformation from a mixed phase to monophasic nature, with minimized volatile imptwities. The microscopic images exhibited homogeneous aggregates of varying shapes and sizes with an average length of about 0.5-5μl. Eu3＋ doped SrGd2O4 phosphors prepared at low temperatures, showed miserably low values of red emission upon UV excitation owing to the presence of volatile impurities. The SrGd2O4：Eu3＋ phosphors prepared at relatively high temperature exhibited strong red-orange emissions due to homogeneously occupied Eu3＋ ions in the host lattice. The dominant red to orange （R/O） emission intensity ratios and CIE parameters of EU3＋ ions substantiated the site occupation of higher asymmetry sites of Gd3＋ ions and the strong covalent nature. Dexter theory and critical distance calculation suggested that the dipole-dipole interaction could be responsible for the concentration quenching of Eu3＋（4 mol.%） doped SrGd2O4 phosphors. Elevated physical and chemical durability and stable photoluminescence made these phosphors suitable for white LEDs and other display applications.

关键词： optical materials chemical synthesis X-ray diffraction luminescence rare earths