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Blast waveform tailoring using controlled venting in blast simulators and shock tubes

Defence Technology（防务技术） 2024年第7期37卷 14-26页

作者： Edward Chern Jinn Gan alex remennikov David Ritzel Faculty of Engineering and Information Sciences University of WollongongWollongongNSW2522Australia Dyn-FX Consulting Ltd 19 Laird Ave NorthAmherstburgONN9V 2T5Canada

A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive *** tubes and blast simulators are often constrained with the lack of effective ways to control blast wave profiles and as a result have a limited performance *** wave shaping techniques employed in some facilities are reviewed but often necessitate extensive geometric modifications,inadvertently cause flow anomalies,and/or are only applicable under very specific *** paper investigates controlled venting as an expedient way for waveforms to be tuned without requiring extensive modifications to the driver or existing geometry and could be widely applied by existing and future blast simulation and shock tube *** use of controlled venting is demonstrated experimentally using the Advanced Blast Simulator(shock tube)at the Australian National Facility of Physical Blast Simulation and via numerical flow simulations with Computational Fluid *** venting is determined as an effective method for mitigating the impact of re-reflected waves within the blast *** control method also allows for the adjustment of parameters such as tuning the peak overpressure,the positive phase duration,and modifying the magnitude of the negative phase and the secondary shock of the blast *** paper is concluded with an illustration of the potential expanded performance range of the Australian blast simulation facility when controlled venting for blast waveform tailoring as presented in this paper is applied.

关键词： Advanced blast simulator Shock wave propagation Far-field explosion Blast loads Blast waves Computational fluid dynamics

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A hybrid tubular standing support for underground mines:Compressive behaviour

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International Journal of Mining Science and Technology 2021年第2期31卷 215-224页

作者： Hongchao Zhao Ting Ren alex remennikov School of Civil Mining and Environmental EngineeringFaculty of Engineering and Information SciencesUniversity of WollongongNSW 2522Australia 2 School of Geology and Mining EngineeringXinjiang UniversityUrumqi 830000China

This paper presents the development of an innovative standing support for underground *** main feature of this standing support is its exterior container,a combination of polyvinyl chloride(PVC)with large rupture strain and fibre-reinforced polymer(FRP)with high strength-to-weight *** demonstrate the advantages of this cementitious grout filled PVC-FRP tubular(PFT)standing support,a series of compression tests were *** variables included the strength of cementitious grout infill material and the thickness of FRP *** tests were also conducted on cementitious grout-filled PVC tubular(PT)support and cementitious grout-filled FRP tubular(FT)*** tests showed that PFT support presents a typical strain-hardening behaviour together with an outstanding axial deformation ability(>20%of the overall height of the support).In addition,the maximum compressive strength of PFT support is much higher than that of the corresponding PT support and FT ***,using thicker FRP jacket or high strength cementitious grout material can enhance the load carrying capacity of PFT *** comparative results indicated that the high performance of PFT support is mainly attributed to the combination of confining constituents(*** and FRP)and infill material.

关键词： Standing support FRP PVC Confinement Composite structures Underground mines

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Developing coal burst propensity index method for Australian coal mines

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International Journal of Mining Science and Technology 2018年第5期28卷 783-790页

作者： Xiaohan Yang Ting Ren Lihai Tan alex remennikov Xueqiu He School of Civil Mining and Environmental Engineering University of Wollongong Centre of Infrastructure Protection and Mining Safety University of Wollongong School of Civil and Environmental Engineering University of Science and TechnologyBeijing

Coal burst is the violent failure of overstressed coal, and it is often accompanied by sound, coal ejection and seismic events. It is subsequently recognized as a serious safety risk of Australia after double fatalities coal burst happened at Austar Coal Mine. Considering the increasing trend of coal burst severity and frequency with mining depth, it is an urgent task to develop the coal burst risk assessment methods for Australia underground coal mines. Coal burst propensity index method is a widely used method of burst risk evaluation of coal as it is summed up from the coal burst research and practice of many *** paper presents the experimental and theoretical research of coal burst propensity index method for coal burst risk assessment in Australia. The definition of four indexes including elastic strain energy index(W_(ET)), bursting energy index(K_E), dynamic failure time(DT) and uniaxial compression strength(RC)is introduced in the first part. Then, the standard laboratory test process and test parameter of coal burst propensity index is presented. DT test is conducted with 0.3 mm/min displacement control loading rate while other test is with 0.5 mm/min. Besides, modified data processing and risk classification method of test are proposed. Differentiate analysis of stress-strain curve is adopted in the data processing of DT and KEindex. A four level risk classification form of burst risk is recommended for Australian underground coal mines. Finally, two likely improvement methods of W_(ET) test, including volumetric strain indicator method and theoretical calculation method, are discussed.

关键词： Coal burst Coal burst propensity Risk evaluation Underground mining

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Evaluation of effectiveness of polymer coatings in reducing blastinduced deformation of steel plates

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Defence Technology（防务技术） 2021年第6期17卷 1895-1904页

作者： Damith Mohotti P.L.N.Fernando Dakshitha Weerasinghe alex remennikov School of Engineering and Information Technology The University of New South WalesCanberraACT2600Australia Department of Civil Engineering Faculty of EngineeringGeneral Sir John Kotelawala Defence UniversityRatmalanaSri Lanka School of Civil Engineering Faculty of EngineeringThe University of SydneyDarlingtonNSW2006Australia Centre for Infrastructure Protection and Mining Safety University of WollongongWollongongNSW2522Australia

Incorporating elastomers such as polymers in protective structures to withstand high energetic dynamic loads,has gained significant *** main objective of this study is to investigate the influence of a Polyurea coating towards the blast-induced response in steel *** such,Polyurea coated steel plates were tested under near-field blast loads,produced by the detonation of 1 kg of spherical nitromethane charges,at a standoff distance of 150 *** steel(XLERPLATE 350)and high-strength steel(BIS80)plates with thicknesses of 10 mm were Polyurea coated with thicknesses of 6 mm and 12 mm on either the front(facing the charge)or the back *** deformation profiles were measured using 3D *** simulations were performed using the non-linear finite element code *** strain-dependent behaviour of the steel and Polyurea were represented by Johnson-cook and Money-Rivlin constitutive models,*** numerical models were validated by comparing the plate deflection results obtained from the experiments and were then used in the subsequent parametric study to investigate the optimum thickness of the Polyurea *** results indicate that back face coating contributes towards an approximately 20%reduction in the residual deformation as well as the absence of melting of the Polyurea layer,while the front-face coating can be used a means of providing additional standoff distance to the steel plates.

关键词： Polyurea coating Near-field blast LS-DYNA Plate deformation ALE

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Novel hybrid FRP tubular columns for sustainable mining infrastructure:Recent research at University of Wollongong

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International Journal of Mining Science and Technology 2014年第3期24卷 311-316页

作者： Yu Tao remennikov alex M. Faculty of Engineering and Information Sciences University of Wollongong

This paper introduces, for applications in the mining industry, an innovative hybrid column form which consists of an inner steel tube, an outer fibre-reinforced polymer(FRP) tube and an annular concrete infill between them. The two tubes may be concentrically placed to produce a section form more suitable for columns, or eccentrically placed to produce a section form more suitable for beams. The FRP is combined with steel and concrete in these hybrid structural members in such a way that the advantages of FRP are appropriately exploited while its disadvantages are minimized. As a result, these hybrid members possess excellent corrosion resistance as well as excellent ductility and seismic resistance. This paper summarizes existing research on this new form of structural members, and discusses their potential applications in mining infrastructure before presenting a summary of the recent and current studies at University of Wollongong(UOW) on their structural behaviour and design.

关键词： Hybrid column Tubular column Fibre reinforced polymer Sustainable mining infrastructure

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RESISTANCE OF RAILWAY CONCRETE SLEEPERS TO IMPACT LOADING

RESISTANCE OF RAILWAY CONCRETE SLEEPERS TO IMPACT LOADING

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The 7th International Conference on Shock and Impact Loads on Structures

作者： alex M remennikov Sakdirat Kaewunruen University of Wollongong

＜正＞Railway sleeper is a main part of railway track *** role is to distribute loads from the rail foot to the underlying ballast *** is a widespread suspicion based on the industry experience that railway concrete sleepers have reserves of strength that are *** is thus important to establish the spectrum and amplitudes of ultimate forces applied to the railway track in order to understand more clearly the manner in which track components including concrete sleepers respond to those *** in concrete sleepers have been visually observed by many railway *** principal cause of cracking is the infrequent but high-magnitude wheel loads produced by a small percentage of"bad"wheels or railhead surface *** loads are of short duration but of very high magnitude. Current design philosophy for prestressed concrete sleepers is based on permissible stress design approach,which does not consider the actual dynamic loads on tracks. In order to devise a new limit states design concept for concrete sleepers,the research efforts are required to perform comprehensive studies of the loading conditions,the static behaviour,the dynamic response,and the impact resistance of the prestressed concrete sleepers. This paper presents the results of experimental and numerical studies aimed at predicting the dynamic responses of railway concrete *** data also provided information on the failure modes for railway prestressed concrete sleepers under static and impact Ioadings.A high-capacity drop weight impact testing machine was constructed at the University of Wollongong to evaluate the ultimate capacity of prestressed concrete sleepers under impact *** absorption capacity of the prestressed concrete sleepers was evaluated to determine the amount of energy required to fail the sleeper under impact *** and impact tests were carried out using the Australian-manufactured prestressed concrete sleepers.

关键词： Impact Loading Concrete Sleepers Limit States Design ANSYS LS-Dyna

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Conics on Barth-Bauer octics

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Science China Mathematics 2024年第7期67卷 1507-1524页

作者： alex Degtyarev Department of Mathematics Bilkent UniversityAnkara06800Turkey

We analyze the configurations of conics and lines on a special class of Kummer octic surfaces. In particular, we bound the number of conics by 176 and show that there is a unique surface with 176 conics, all irreducible: it admits a faithful action of one of the Mukai groups. Therefore, we also discuss conics and lines on Mukai surfaces: we discover a double plane(ramified at a smooth sextic curve) that contains 8,910 smooth conics.

关键词： K3-surface octic surface Kummer surface conic Mukai group

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Developing the new soil science——Advice for early-career soil scientists

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Pedosphere 2024年第1期34卷 3-4页

作者： alex McBRATNEY Sydney Institute of Agriculture&School of Life and Environmental Sciences The University of SydneySydney NSW 2006Australia

Confucius said,“To know what you know and what you do not know, that is true knowledge.”Hartemink (2006) edited a prescient book on the future of soil science, the contents of which are worthy of consideration today. Since then, there has been a growing emphasis on soil carbon, soil health, and soil security, as well as increased capability of technology related to machine leaning and soil sensing and *** KNOWLEDGE DISCOVERY CATEGORISATION Based on the above ancient aphorism attributed to Confucius, the author writing in Hartemink (2006) classified soil knowledge and knowledge discovery into 4 categories. An updated version is given in Fig. 1.

关键词： soil measurement. leaning

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No evidence of predator odor avoidance in a North American bird community

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Avian Research 2024年第1期15卷 133-138页

作者： Austin Dotta Batur Yaman alex Van Huynh Department of Biology DeSales University2755 Station AvenueCenter ValleyPAUSA

Recent advances in our understanding of avian chemical communication have highlighted the importance of olfaction in many aspects of avian *** studies investigating predator avoidance behaviors in response to predator odor cues have produced mixed results across species and *** we assess if a community of birds in eastern Pennsylvania displays avoidance behaviors towards predator odor cues in a natural foraging *** use clay caterpillars to measure foraging activity by birds in the presence of predator(bobcat)urine,non-predator(rabbit)urine,and water controls in two different environmental contexts(field ***).Although we detected a weak trend for birds to forage less at predator urine-treated sites,we found no significant difference in avian foraging between the site *** did find that foraging rates between environmental contexts changed significantly over the course of the experiment,with forest sites showing decreasing foraging rates and field sites showing increasing foraging *** results reinforce the published literature that avoidance of predator odors by birds may not be ubiquitous across contexts and species.

关键词： Foraging Odor Olfaction Predation Predator-avoidance

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Kinematics ofmandibular advancement devices(MADs):Why do some MADs move the lower jaw backward duringmouth opening?

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Bio-Design and Manufacturing 2024年第5期7卷 637-650页

作者： Juan A.Cabrera alex Bataller Sergio Postigo Marcos García Mechanical Engineering Department University of Malaga29071 MalagaSpain

Mandibular advancement devices(MADs)are widely used treatments for obstructive sleep *** function by advancing the lower jaw to open the upper *** increase patient comfort,most patients allow the mouth to be ***,not all systems maintain the lower jaw in a forward position during mouth opening,which results in the production of a retrusion that favors the collapse of the upper ***,the kinematic behavior of the mechanism formed by the mandible-device assembly depends on jaw *** means that,during mouth opening,some devices cause lower jaw protrusion in some patients,but cause its retraction in *** this study,we report the behavior of well-known devices currently on *** do so,we developed a kinematic model of the lower jawdevice *** validated for all devices analyzed using a high-resolution camera *** results show that some of the devices analyzed here did not produce the correct behavior during patient mouth opening.

关键词： Mandibular advancement devices Lower jaw kinematics Sleep apnea

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