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Numerical and analytical simulation of the structural behaviour of fully grouted cable bolts under impulsive loading

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International Journal of Mining Science and Technology 2018年第5期28卷 807-811页

作者： Faham Tahmasebinia Chengguo Zhang Ismet Canbulat Onur Vardar Serkan Saydam School of Minerals and Energy Resources Engineering University of New South Wales

Designing reliable yielding support system to mitigate the effect of the kinetic energy in burst-prone conditions in mining and tunneling excavations is one of the challenges for geotechnical engineers. A combination of the support elements can be used to increase rock strength and minimise the displacement of unstable rock mass. It is important to understand how the support system works to ensure the stability of underground excavations. Cable bolts have been commonly used as an effective underground support system and an element of reinforcement to improve rock stability. Cable bolts are usually considered to be subjected to static loads under relatively low stress environments, however, in burst-prone conditions, they might be subjected to dynamic loads. Cable bolts as well as other support elements are used in burst-prone conditions to absorb the kinetic energy of the removed rock to avoid sudden and violent failures. This paper develops numerical and a novel analytical simulation technique for cable bolts to assess their structural behaviour under static and dynamic loading conditions. The numerical and analytical models are then validated against experimental observations reported in the literature, which demonstrates the reliability of the proposed models.

关键词： Cable bolts Yielding support Coal burst Shear dynamic loading

Do phytotoxic allelochemicals remain in ashes after burning Chrysanthemoides monilifera subsp. monilifera(boneseed)?

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Journal of Environmental Sciences 2016年第6期28卷 109-119页

作者： Md.Abdullah Yousuf Al Harun Joshua Johnson Randall W.Robinson Institute for Sustainability and Innovation College of Engineering and ScienceVictoria University

Australia is facing challenges in controlling Chrysanthemoides monilifera subsp. monilifera（boneseed）. However, burning has achieved some success in this regard. We aimed to investigate the comparative phytotoxicity of boneseed dried powder and ashes（burnt at 450℃ and250℃）. Phenolic compounds in powder and ashes were measured using Folin–Ciocalteu assay and HPLC. The phytotoxicity of boneseed powder and ash extracts was assessed through germination bioassay on Lactuca sativa and the phytotoxicity of litter and ashes was evaluated using field soil, both in growth chamber. Burning of boneseed reduced total phenolics in ashes of boneseed organs by 99% and 100% both at high and low temperatures. The four phenolic compounds that were detected in boneseed were either absent or at negligible levels in the ashes,with inversely related to temperature. Both boneseed ash extracts and litter ash-mediated soil significantly reduced phytotoxicity displaying increased germination, biometric and biochemical parameters of test species compared with unburnt powder extracts and litter powder-mediated soil respectively, with greater reduction of phytotoxicity found for ashes produced at the lower temperature. Interestingly, the ash extracts and litter ash-mediated soil were found to stimulate some of those parameters of the test species compared to control. There was no excessive reactive oxygen species（ROS） produced in test species exposed to ash extracts compared with unburnt powder extracts. These findings suggest that burning of boneseed is an appropriate method of weed control and that this approach will reduce phytotoxicity of this species on native plants.

关键词： Boneseed Burning Phenolic compounds HPLC Phytotoxicity ROS

The effects of temperature on decomposition and allelopathic phytotoxicity of boneseed litter

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Journal of Environmental Sciences 2015年第7期27卷 1-11页

作者： Md.Abdullah Yousuf Al Harun Joshua Johnson Md.Nazim Uddin Randall W.Robinson Institute for Sustainability and Innovation College of Engineering and Science Victoria UniversityMelbourne

Decomposition of plant litter is a fundamental process in ecosystem function, carbon and nutrient cycling and, by extension, climate change. This study aimed to investigate the role of temperature on the decomposition of water soluble phenolics（WSP）, carbon and soil nutrients in conjunction with the phytotoxicity dynamics of Chrysanthemoides monilifera subsp. monilifera（boneseed） litter. Treatments consisted of three factors including decomposition materials（litter alone, litter with soil and soil alone）, decomposition periods and temperatures（5-15, 15-25and 25-35°C（night/day））. Leachates were collected on 0, 5, 10, 20, 40 and 60 th days to analyse physico-chemical parameters and phytotoxicity. Water soluble phenolics and dissolved organic carbon（DOC） increased with increasing temperature while nutrients like SO-24 and NO-13 decreased. Speed of germination, hypocotyl and radical length and weight of Lactuca sativa exposed to leachates were decreased with increasing decomposition temperature. All treatment components had significant effects on these parameters. There had a strong correlation between DOC and WSP, and WSP content of the leachates with radical length of test species. This study identified complex interactivity among temperature, WSP, DOC and soil nutrient dynamics of litter occupied soil and that these factors work together to influence phytotoxicity.

关键词： Temperature Boneseed Phenolics DOC Nutrient cycling Phytotoxicity

Nano-machining of materials： understanding the process through molecular dynamics simulation

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Advances in Manufacturing 2017年第1期5卷 20-34页

作者： Dan-Dan Cui Liang-Chi Zhang Laboratory for Precision and Nano Processing TechnologiesSchool of Mechanical and Manufacturing Engineering TheUniversity of New South Wales Sydney NSW 2052Australia

Molecular dynamics （MD） simulation has been widely applied in various complex, dynamic processes at atomistic scale, because an MD simulation can provide some deformation details of materials in nano-processing and thus help to investigate the critical and important issues which cannot be fully revealed by experiments. Extensive research with the aid of MD simulation has provided insights for the development of nanotechnology. This paper reviews the fundamentals of nano-machining from the aspect of material structural effects, such as single crystalline, polycrystalline and amorphous materials. The classic MD simulations of nano-indentation and nano-cutting which have aimed to investigate the machining mechanism are discussed with respect to the effects of tool geometry, material properties and machining parameters. On nano-milling, the discussion focuses on the understanding of the grooving quality in relation to milling conditions.

关键词： Molecular dynamics Nano-milling Nano-indentation Nano-cutting Groove quality Multi-grooving

Mechanical proper ties of lateral transition metal dichalcogenide heterostructures

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Frontiers of physics 2021年第1期16卷 23-29页

作者： Sadegh Imani Yengejeh William Wen Yun Wang Centre for Clean Environment and Energy School of Environment and ScienceGriffith UniversityGold Coast CampusSouthport 4222Australia

Transition metal dichalcogenide(TMD)monolayers attract great attention due to their specific structural,electronic and mechanical *** formation of their lateral heterostructures allows a new degree of flexibility in engineering electronic and optoelectronic ***,the mechanical properties of the lateral heterostructures are rarely *** this study,a comparative investigation on the mechanical characteristics of 1H,IT'and 1H/1T'heterostructure phases of different TMD monolayers including molybdenum disulfide(M0S_(2))molybdenum diselenide(MoSe_(2)),Tungsten disulfide(WS_(2)),and Tungsten diselenide(WSe_(2))was conducted by means of density functional theory(DFT)*** results indicate that the impact of the lateral heterostructures has a relatively weak mechanical strength for all the TMD *** significant correlation bet ween the mechanical properties of the TMD monolayers and their structural phases can be used to tune their stiffness of the *** findings,therefore,suggest a novel strategy to manipulate the mechanical characteristics of TMDs by engineering their structural phases for their practical applications.

关键词： transition metal dichalcogenide lateral heterostructures mechanical properties in-plane stiffness tensor density functional theory

POCl3 diffusion for industrial Si solar cell emitter formation

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Frontiers in Energy 2017年第1期11卷 42-51页

作者： Hongzhao LI Kyung KIM Brett HALLAM Bram HOEX Stuart WENHAM Malcolm ABBOTT School of Photovoltaic and Renewable Energy Engineering UNSW Australia Sydney NSW 2052 Australia

POCl3 diffusion is currently the de facto standard method for industrial n-type emitter fabrication. In this study, we present the impact of the following processing parameters on emitter formation and electrical performance： deposition gas flow ratio, drive-in tempera- ture and duration, drive-in O2 flow rate, and thermal oxidation temperature. By showing their influence on the emitter doping profile and recombination activity, we provide an overall strategy for improving industrial POCl3 tube diffused emitters.

关键词： POCl3 diffusion emitter recombination oxidation silicon

Laser enhanced gettering of silicon substrates

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Frontiers in Energy 2017年第1期11卷 23-31页

作者： Daniel CHEN Matthew EDWARDS Stuart WENHAM Malcolm ABBOTT Brett HALLAM School of Photovoltaic and Renewable Energy Engineering University of New South Wales Kensington NSW 2052 Australia

One challenge to the use of lightly-doped, high efficiency emitters on multicrystalline silicon wafers is the poor gettering efficiency of the diffusion processes used to fabricate them. With the photovoltaic industry highly reliant on heavily doped phosphorus diffusions as a source of gettering, the transition to selective emitter structures would require new alternative methods of impurity extraction. In this paper, a novel laser based method for gettering is investigated for available silicon wafers used its impact on commercially in the manufacturing of solar cells. Direct comparisons between laser enhanced gettering （LasEG） and lightly-doped emitter diffusion gettering demonstrate a 45% absolute improvement in bulk minority carrier lifetime when using the laser process. Although grain boundaries can be effective gettering sites in multicrystalline wafers, laser processing can substantially improve the performance of both grain boundary sites and intra-grain regions. This improvement is correlated with a factor of 6 further decrease in interstitial iron concentra- tions. The removal of such impurities from multicrystalline wafers using the laser process can result in intra-grain enhancements in implied open-circuit voltage of up to 40 mV. In instances where specific dopant profiles are required for a diffusion on one surface of a solar cell, and the diffusion process does not enable effective gettering, LasEG may enable improved gettering during the diffusion process.

关键词： gettering multicystaline silicon impurities,laser doping

Statistical analysis of recombination properties of the boronoxygen defect in p-type Czochralski silicon

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Frontiers in Energy 2017年第1期11卷 4-22页

作者： Nitin NAMPALLI Tsun Hang FUNG Stuart WENHAM Brett HALLAM Malcolm ABBOTT School of Photovoltaic and Renewable Energy Engineering Universityof New South Wales Sydney NSW 2052 Australia

This paper presents the application of lifetime spectroscopy to the study of carrier-induced degradation ascribed to the boron-oxygen （BO） defect. Specifically, a large data set of p-type silicon samples is used to investigate two important aspects of carrier lifetime analysis： ① the methods used to extract the recombination lifetime associated with the defect and ② the underlying assumption that cartier injection does not affect lifetime components unrelated to the defect. The results demonstrate that the capture cross section ratio associated with the donor level of the BO defect （kl） vary widely depending on the specific method used to extract the defect-specific recombination lifetime. For the data set studied here, it was also found that illumination used to form the defect caused minor, but statistically significant changes in the surface passivation used. This violation of the fundamental assumption could be accounted for by applying appropriate curve fitting methods, resulting in an improved estimate of k1 （11.90±0.45） for the fully formed BO defect when modeled using the donor level alone. Illumination also appeared to cause a minor, apparently injectionindependent change in lifetime that could not be attributed to the donor level of the BO defect alone and is likely related to the acceptor level of the BO defect. While specific to the BO defect, this study has implications for the use of lifetime spectroscopy to study other carrier induced defects. Finally, we demonstrate the use of a unit-less regression goodness-of-fit metric for lifetime data that is easy to interpret and accounts for repeatability error.

关键词： Czochralski silicon boron-oxygen defect,injection dependent lifetime spectroscopy goodness-of-fit,repeatability error

Vision and photoentrainment in fishes: The effects of natural and anthropogenic perturbation

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Integrative Zoology 2015年第1期10卷 15-28页

作者： Shaun P.COLLIN Nathan S.HART School of Animal Biology and the Oceans Institute University of Western AustraliaCrawleyWestern AustraliaAustralia

Vision and photoentrainment in fishes are vital for feeding,avoiding predation,spatial orientation,navigation,social communication and the synchronization of many homeostatic functions such as activity patterns and *** camera-like(image-forming)eyes of fishes are optimized to provide a clear view of their preferred ecological niche,while non-visual photoreceptors provide irradiance detection that mediates circadian photoentrainment,an endogenous time-keeping mechanism(biological clock)to respond to predictable changes in environmental *** and fisheries are under pressure from both natural and anthropogenic perturbation,which in many cases alters the intensity and spectral composition of the light environment on which they depend for their *** review examines the effects of a changing light environment and turbidity on the health of fishes within a developmental and ecological *** the sensory environment of fishes is vital to predicting their responses and,ultimately,their resilience to environmental change and the potential for maintaining sustainable levels of biodiversity.

关键词： circadian rhythms ecology environment photoreception turbidity