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Numerical modelling of resonance mechanisms in jointed rocks using transfer functions

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第5期15卷 1076-1089页

作者： Harry holmes Chrysothemis Paraskevopoulou mark Hildyard Krishna Neaupane David P.Connolly School of Earth and Environment University of LeedsLeedsLS29JTUK AECOM Ltd. ChesterfieldS417SLUK

Resonance effects in parallel jointed rocks subject to stress waves are investigated using transfer functions,derived from signals generated through numerical *** is important for a range of engineering situations as it identifies the frequency of waves which will be favourably *** different numerical methods are used for this study,adopting the finite difference method and the combined discrete element-finite difference *** numerical models are validated by replicating results from previous *** two methods are found to behave similarly and show the same resonance effects;one operating at low frequency and the other operating at relatively high *** resonance effects are interpreted in terms of simple physical systems and analytical equations are derived to predict the resonant frequencies of complex rock *** frequency resonance is shown to be generated by a system synonymous with masses between springs,described as spring resonance,with an equal number of resonant frequencies as the number of *** frequency resonance is generated through superposition of multiple reflected waves developing standing waves within intact blocks,described as superposition *** resonance through superposition has previously been identified,resonance based on masses between springs has not been previously identified in jointed *** findings of this study have implications for future analysis of multiple jointed rock masses,showing that a wave travelling through such materials can induce other modes of propagation of waves,*** resonance.

关键词： Resonance Jointed rocks Finite difference method Discrete element Transfer functions Wave propagation

Metabolic phenotyping in health and disease

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四川生理科学杂志 2024年第4期46卷 908-908页

作者： Elaine holmes 不详

Analyzing metabolites(small molecules<1 kDa)in body fluids such as urine and plasma using various spectroscopic methods provides information on the metabotype(metabolic phenotype)of individuals or populations,informat... 详细信息

关键词： urine Metabolic body

Monitoring the mode of action of synthetic and natural biocides against Aeromonas hydrophila by Raman spectroscopy and chemometrics

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Journal of Leather Science and Engineering 2021年第1期3卷 230-244页

作者： Megha Mehta Yang Liu mark Waterland Geoff holmes NZ Leather and Shoe Research Association(LASRA®) Palmerston NorthNew Zealand School of Fundamental Sciences Massey UniversityPalmerston NorthNew Zealand

We have investigated the mode of action of synthetic biocides,(2-(thiocyanomethylthio)benzothiazole(TCMTB),dichlorophen,(commonly used in leather industry for preservation)and natural biocides,oregano and eucalyptus oils,on Aeromonas hydrophila using Raman spectroscopy in collaboration with multivariate analysis and 2D correlation spectroscopy to evaluate whether Raman spectra acquired contained valuable information to study the action of biocides on bacterial *** growth of *** in clear and outer edge zone of inhibition differ in their reaction with different biocides,which allows us to highlight the differences as a characteristic of two kinds of *** classification helps identify oregano oil as the most effective biocide by altering clear and outer edge zone of *** disk diffusion assay method was used for screening biocide bacteria interactions and later analysed by Raman *** paper also presents the introduction of TCMTB and oregano oil into leather processing stages to examine and determine the antimicrobial effect as an application to real-world ***,we conclude that Raman spectroscopy with appropriate computational tools constitutes a powerful approach for screening biocides,which provide solutions to all the industries using biocides including leather industry,considering the potentially harmful effect of biocides to humans and the environment.

关键词： Biocides Chemometrics Aeromonas hydrophila Principal component analysis Raman spectroscopy Inhibition

RAMAN AND ATR-FTIR SPECTROSCOPY TOWARDS CLASSIFICATION OF WET BLUE BOVINE LEATHER USING RATIOMETRIC AND CHEMOMETRIC ANALYSIS

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Journal of Leather Science and Engineering 2020年第1期2卷 23-37页

作者： Megha Mehta Rafea Naffa Catherine Maidment Geoff holmes mark Waterland NZ Leather and Shoe Research Association(LASRA®) Palmerston NorthNew Zealand School of Fundamental Sciences Massey UniversityPalmerston NorthNew Zealand

There is a substantial loss of value in bovine leather every year due to a leather quality defect known as“looseness”.Data show that 7%of domestic hide production is affected to some degree,with a loss of$35m in export *** investigation is devoted to gaining a better understanding of tight and loose wet blue leather based on vibrational spectroscopy observations of its structural variations caused by physical and chemical changes that also affect the tensile and tear *** regions from the wet blue leather were selected for *** of wet blue bovine leather were collected and studied in the sliced form using Raman spectroscopy(using 532 nm excitation laser)and Attenuated Total Reflectance-Fourier Transform InfraRed(ATR-FTIR)*** purpose of this study was to use ATR-FTIR and Raman spectra to classify distal axilla(DA)and official sampling position(OSP)leather samples and then employ univariate or multivariate analysis or *** univariate analysis,the 1448 cm^(-1)(CH_(2) deformation)band and the 1669 cm^(-1)(Amide I)band were used for evaluating the lipid-to-protein ratio from OSP and DA Raman and IR spectra as indicators of leather ***-fitting by the sums-of-Gaussians method was used to calculate the peak area ratios of 1448 and 1669 cm^(-1 )*** ratio values obtained for DA and OSP are 0.57±0.099,0.73±0.063 for Raman and 0.40±0.06 and 0.50±0.09 for *** results provide significant insight into how these regions can be ***,to identify the spectral changes in the secondary structures of collagen,the Amide I region(1600-1700 cm^(-1))was investigated and curve-fitted-area ratios were *** 1648:1681 cm^(-1)(non-reducing:reducing collagen types)band area ratios were used for Raman and 1632:1650 cm^(-1)(triple helix:α-like helix collagen)for *** ratios show a significant difference between the two *** support this qualitative analysis,logistic regression was performed on t

关键词： Raman spectroscopy Attenuated Total reflectance-Fourier transform InfraRed spectroscopy Principal component analysis Linear discriminant analysis Wet blue Distal axilla Official sampling position

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

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Nano Research 2014年第1期7卷 1-62页

作者： mark J. Armstrong Colm O'Dwyer William J. Macklin Justin. D. holmes Materials Chemistry & Analysis Group Department of Chemistry and the Tyndall National Institute University College Cork Cork Ireland Applied Nanoscience Group Department of Chemistry and the Tyndall National Institute University College Cork Cork Ireland Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) Trinity College Dublin Dublin 2 Ireland Nexeon Limited Abingdon Oxfordshire UK.

The performance of the lithium-ion cell is heavily dependent on the ability of the host electrodes to accommodate and release Li＋ ions from the local structure. While the choice of electrode materials may define parameters such as cell potential and capacity, the process of intercalation may be physically limited by the rate of solid-state Li＋ diffusion. Increased diffusion rates in lithium-ion electrodes may be achieved through a reduction in the diffusion path, accomplished by a scaling of the respective electrode dimensions. In addition, some electrodes may undergo large volume changes associated with charging and discharging, the strain of which, may be better accommodated through nanostructuring. Failure of the host to accommodate such volume changes may lead to pulverisation of the local structure and a rapid loss of capacity. In this review article, we seek to highlight a number of significant gains in the development of nanostructured lithium-ion battery architectures （both anode and cathode）, as drivers of potential next-generation electrochemical energy storage devices.

关键词： lithium ion batteries nanostructuring anodes cathodes

Humid Little Ice Age in arid central Asia documented by Bosten Lake, Xinjiang, China

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Science China Earth Sciences 2006年第12期49卷 1280-1290页

作者： J. A. holmes ECRC Department of Geography University College London

Short sediment cores retrieved from Bosten Lake, the largest inland freshwater lake in China, were used to explore humidity and precipitation variations in arid central Asia during the past millennium. The chronology of the cores was established using 137Cs, 210Pb and AMS 14C dating re- sults. Multi-proxy high-resolution analysis, including pollen ratios of Artemisia and Chenopodiaceae (A/C), carbonate content and grain size, indicates that the climate during the past millennium can be divided into three stages: a dry climate between 1000―1500 AD, a humid climate during the Little Ice Age (LIA) (c. 1500―1900 AD), and a warm dry period after 1900 AD. On centennial timescales, the climate change in northwestern China during the past 1000 years is characterized by oscillations between warm-dry and cold-humid climate conditions. All the proxies changed significantly and indi- cate increased precipitation during the LIA, including increased pollen A/C ratios and pollen concen- trations, decreased carbonate content and increased grain size. The humid period during the LIA re- corded by the Bosten Lake sediments is representative of arid central Asia and is supported by nu- merous records from other sites. During the LIA, the water runoff into the Keriya River and Tarim River in the Tarim Basin increased, while the ice accumulation in the Guliya ice core increased. Additionally, the lake levels of the Aral and Caspian Sea also rose, while tree-ring analysis indicates that precipita- tion increased. We hypothesize that both the lower temperature within China and the negative anomalies of North Atlantic Oscillation (NAO) during this period may have contributed to the humid climate within this area during LIA.

关键词： multiproxy analyses,Bosten Lake,humid Little Ice Age,past millennium,arid central Asia.

Inducing imperfections in germanium nanowires

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Nano Research 2017年第5期10卷 1510-1523页

作者： Subhajit Biswas Sven Barth Justin D. holmes Materials Chemistry & Analysis Group Department of Chemistry and the Tyndall National lnstitute University College Cork Cork Ireland AMBER@CRANN Trinity College Dublin Dublin 2 Ireland Vienna University of Technology Institute of Materials Chemistry Getreidemarkt 9/BCI02 1060 Vienna Austria

Nanowires with inhomogeneous heterostructures such as polytypes and periodic twin boundaries are interesting due to their potential use as components for optical, electrical, and thermophysical applications. Additionally, the incorporation of metal impurities in semiconductor nanowires could substantially alter their electronic and optical properties. In this highlight article, we review our recent progress and understanding in the deliberate induction of imperfections, in terms of both twin boundaries and additional impurities in germanium nanowires for new/enhanced functionalities. The role of catalysts and catalyst-nanowire interfaces for the growth of engineered nanowires via a three-phase paradigm is explored. Three-phase bottom-up growth is a feasible way to incorporate and engineer imperfections such as crystal defects and impurities in semiconductor nanowires via catalyst and/or interfacial manipulation. ＂Epitaxial defect transfer＂ process and catalyst-nanowire interfacial engineering are employed to induce twin defects parallel and perpendicular to the nanowire growth axis. By inducing and manipulating twin boundaries in the metal catalysts, twin formation and density are controlled in Ge nanowires. The formation of Ge polytypes is also observed in nanowires for the growth of highly dense lateral twin boundaries. Additionally, metal impurity in the form of Sn is injected and engineered via third-party metal catalysts resulting in above-equilibrium incorporation of Sn adatoms in Ge nanowires. Sn impurities are precipitated into Ge bi-layers during Ge nanowire growth, where the impurity Sn atoms become trapped with the deposition of successive layers, thus giving an extraordinary Sn content （〉6 at.%） in Ge nanowires. A larger amount of Sn impingement （〉9 at.%） is further encouraged by utilizing the eutectic solubility of Sn in Ge along with impurity trapping.

关键词： germamum nanowire vapor-liquid-solid (VLS)growth twinning impurity incorporation

Combating Corruption in China: The Role of the State and Other Agencies in Comparative Perspective

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Economic and Political Studies 2015年第1期3卷 42-70页

作者： LESLIE holmes the School of Social and Political Sciences University of Melbourne

This paper is the first to compare China’s current anticorruption approach with those of both post-communist and other Sinic states/*** principal purpose is to compare anti-corruption in China with the situation in countries that constitute appropriate comparators—either systemically(post-communist transition states)or culturally(predominantly Sinic states/regions)—and suggest ways in which China could usefully learn from these comparators.A comparative public policy evaluative approach forms the core of the *** study uses publicly available survey data,both perceptual and experiential,for drawing inferences about the corruption levels in China and the other states analyzed.A neo-Weberian approach to system legitimacy and delegitimation is employed in analyzing the potential dangers of a radical anti-corruption approach,while Giddensian structuration theory is used to emphasize the interplay between structure and agency in *** findings and value of this research are primarily practical,in that it highlights potential lessons China could learn from Singapore and the Hong Kong SAR while also identifying the principal obstacles to the adoption of such *** particular,the establishment of a single and independent anti-corruption agency would almost certainly have a positive impact on the reduction of corruption *** this is politically difficult,since such a body could be perceived as constituting a threat to the Communist ***,all comparisons betweenstates are limited,since some features are unique to a given country.

关键词： corruption communism post-communism transition

Meta-analysis of ground movements associated with deep excavations using a data mining approach

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 409-416页

作者： Harry holmes Emilio Garcia-Taengua Raul Fuentes AECOM Ltd. University of Leeds

This paper presents a rigorous statistical approach to identify the controlling factors in the development of ground movements associated with deep excavations. It also gives the most suitable definition of support stiffness from many suggested definitions in the literature. The study is based on a newly compiled database from 389 case studies of propped and anchored excavations. Data mining techniques(e.g. principal component analysis and multi-linear regression) were used to identify significant relationships between the parameters under study and to quantify the global trends in the database. The study shows that the main factors controlling the ground movements are those related to ground conditions, confirming the conclusions of previous empirical studies. It is also shown that the definition of Addenbrooke et al.(1994) is the most suitable expression of support stiffness, therefore providing conclusive evidence for its future use.

关键词： Geomechanics Slope stability Special soil Unsaturated soil