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Optimal use of mobile cooling units in a deep-level gold mine

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International journal of Mining Science and Technology 2020年第4期30卷 547-553页

作者： H.j.van Staden j.F.van Rensburg H.j.groenewald Centre for Research and Continued Engineering Development North-West UniversityPretoria 0081South Africa

The South African gold mining sector remains a significant contributor to the country’s *** several challenges that hinder the realisation of South Africa’s full mineral potential,the sector’s sustainability and profitability can be enhanced through implementing operational improvement *** cooling units(MCUs)were identified as a potential focus area for operational *** are used as tertiary or in-stope cooling in hot underground *** this paper,a method was presented to characterise the performance of existing MCUs based on three key performance indicators(KPIs),namely,the wet-bulb temperature ratio(WTR),efficiency and *** strategies were then elected and implemented based on these *** implementation of this method in a South African gold mine attained a reduction in pumped water volumes,reduced operating costs through electricity cost savings and improvements in underground ventilation air temperatures.

关键词： Mobile cooling units Optimisation Mine cooling performance Electricity cost savings Spot cooling

Redefining common endophytes and plant pathogens in Neofabraea,Pezicula,and related genera

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Redefining common endophytes and plant pathogens in Neofabra...

Chaetomium-like fungi causing opportunistic infections in humans:a possible role for extremotolerance

中国菌物学会2015年学术年会

作者： Chen Chen Gerard j.M.Verkley Guangyu Sun j.hannes z.groenewald Pedro W.Crous State Key Laboratory of Crop Stress Biology in Arid Areas and College of Plant Protection Northwest A&F University

Species in Neofabraea, Pezicula, and related genera have been reported as saprobes, plant pathogens or endophytes from a wide range of hosts. The asexual morphs of Neofabraea and Pezicula had been placed in Cryptosporiopsis, now a synonym of Pezicula, while Neofabraea was also linked to Phlyctema. Based on morphology and molecular data of the partial large subunit nr DNA（LSU）, the internal transcribed spacer region with intervening 5.8S nrDNA（ITS）, partial β-tubulin region（tub2）, and the partial RNA polymerase II second largest subunit region（rpb2）, the taxonomy and phylogenetic relationships of these fungi were investigated. Five new species were described in Pezicula based on morphology, while a further eight unnamed phylogenetic lineages revealed further diversity in the genus. Based on these results, the generic concept of Neofabraea was also emended. Phlyctema, which was previously associated with Neofabraea, formed a distinct clade, separate from Neofabraea s. str. Two new neofabraea-like genera, Parafabraea and Pseudofabraea were proposed, along with one new combination in Neofabraea s. str. To stabilise the application of these names, an epitype was designated for Pe. carpinea, the type species of Pezicula, and for N. malicorticis, the type species of Neofabraea.

关键词： Dermateaceae Helotiales multi-gene phylogeny systematics

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Fungal Diversity 2016年第1期76卷 11-26页

作者： Sarah A.Ahmed ziauddin Khan Xue-wei Wang Tarek A.A.Moussa Hassan S.Al-zahrani Omar A.A.lmaghrabi Deanna A.Sutton S.Ahmad j.hannes z.groenewald A.Alastruey-Izquierdo Anne van Diepeningen S.B.j.Menken M.j.Najafzadeh Pedro W.Crous Oliver Cornely Axel Hamprecht Maria j.G.T.Vehreschild A.j.Kindo G.Sybren de Hoog Faculty of Medical Laboratory Sciences University of KhartoumKhartoumSudan CBS-KNAW Fungal Biodiversity Centre P.O.Box 851673508 AD UtrechtThe Netherlands Institute for Biodiversity and Ecosystem Dynamics University of AmsterdamAmsterdamThe Netherlands Department of Microbiology Faculty of MedicineKuwait UniversityKuwaitKuwait State Key Laboratory of Mycology Institute of MicrobiologyChinese Academy of SciencesBeijingChina Biological Sciences Department Faculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia Botany and Microbiology Department Faculty of ScienceCairo UniversityGizaEgypt Fungus Testing Laboratory Department of PathologyUniversity of Texas Health Science Center at San AntonioSan AntonioTXUSA Mycology Reference Laboratory National Centre for MicrobiologyCarlos III Institute of Health(Servicio deMicologíaCentro Nacional de MicrobiologíaInstituto de Salud Carlos III)MadridSpain Department of Parasitology and Mycology Mashhad University of Medical SciencesMashhadIran German Centre for Infection Research(DzIF)at Cologne/Bonn First Department of Internal MedicineUniversity Hospital of CologneCologneGermany Institute for Medical Microbiology Immunology and HygieneUniversity of CologneCologneGermany Department of Microbiology Sri Ramachandra UniversityPorurChennaiIndia Peking University Health Science Center Research Center for Medical MycologyBeijingChina Sun Yat-Sen Memorial Hospital Sun Yat-Sen UniversityGuangzhouChina Shanghai Institute of Medical Mycology Changzheng HospitalSecond Military Medical UniversityShanghaiChina 17 Basic Pathology DepartmentFederal University of ParanáStateCuritibaParanáBrazil

Members of the family Chaetomiaceae are ubiquitous ascosporulating fungi commonly,which reside in soil enriched with manure or cellulosic *** role as human pathogens is largely ***,the ability of some species to grow at high temperature enables them to play an important role as opportunistic *** family contains several genera and species that have never been reported to cause human ***,three new species are described;two belong to the genus Subramaniula and one represents a Chaetomium *** asteroides was isolated from various sources including eye and skin infections as well as from the natural environment,and *** was isolated from a toe *** anamorphosum was isolated from a kidney transplant patient suffering from fungal *** species described were previously misidentified as Papulaspora *** to the formation of cellular clumps or bulbil-like structures,which are characteristic of *** isolates failed to form sexual fruit bodies and ascospores remained absent,which is an unusual feature for the generally ascosporulating genera Chaetomium and Subramaniula;minute conidia from phialides were sometimes observed.

关键词： Chaetomium Desert fungi Keratitis Papulaspora Peritonitis Sterile fungi Subramaniula

Partition method and experimental validation for impact dynamics of flexible multibody system

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Acta Mechanica Sinica 2018年第3期34卷 482-492页

作者： j.Y.Wang z.Y.Liu j.z.Hong School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University

The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields： multibody system dynamics （MBS） and computational solid mechanics （CSM）. Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed： the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-rive formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.

关键词： Partition method Impact dynamics Experimental investigation Efficiency and accuracy Partition principle

KINETICS OF TEMPER EMBRITTLEMENT IN 2.25Cr-1Mo STEEL USED FOR HOT-WALL HYDROFINING REACTORS

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Acta Metallurgica Sinica(English Letters) 2004年第2期17卷 139-146页

作者： j.z.Tan CollegeofMechanicalandPowerEngineering NanjingUniversityofTechnologyNanjing210009China

Based on the theory of grain boundary segregation, a kinetics model of temper em-brittlement caused by long-term service for hot-wall hydrofining reactors was *** kinetics model was applied to phosphorus (P) segregation in 2.25Cr-1Mo steelused for a hot-wall hydrofining reactor, and the kinetics of grain boundary segrea-tion of impurity P in the steel exposed to the process environment of the hydrofiningreactor was calculated on the basis of the model. The Auger electron spectroscopytest was performed in order to determine the grain boundary concentration of P. Theexperimental result is agreement with the theoretical calculated data. The results showthat the kinetics equation is reasonable for predicting the levels of grain boundarysegregation of impurity P in 2.25Cr-1Mo steel used for hot-wall hydrofining reactors.

关键词： hydrofining reactor 2.25Cr-1Mo steel temper embrittlement kinetics

THERMODYNAMICS OF CERIUM CARBIDE Fe_4Ce_4C_7 IN STEEL

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Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 150-156页

作者： j.z.zhang D.z.Li Guizhou Univ of Technology Guiyang China

The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main results obtained can be summarized as follows: The cerium carbide CeC2 can be precipitated in cast steel and distributed along the grain boundaries. Heat treating the steel as austenite, the CeC2 transformed into ternary compound Fe4Ce4 C7, its thermodynamics of formation in steel being expressed as: ac exp(6400/T-6. 28), where 1015Kzed light, opaque in dark field and a little greyer than iron matrix in bright field. Its Vickers hardness is about 420kg/mm2 (annealed) and 750kg/mm2 (quenched). This phase in steel is stable in basic and organic solutions and can be seperated from the matrix by electrolysis. Moreover, the LaC2 in steel can not be transformed into Fe-La-C ternary compound in present investigation.

关键词： cerium carbide electrolytic separation thermodynamics

Effect of Variable Selection on Multidisciplinary Design Optimization:a Flight Vehicle Example

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Chinese journal of Aeronautics 2007年第1期20卷 86-96页

作者： j.Roshanian z.Keshavarz MDO Laboratory Aerospace Engineering Department of K.N. Toosi University of Technology East Vafadar blvd 4th Tehranpars sq. 16579 Tehran Iran.

Different multidisciplinary design optimization （MDO） problems are formulated and compared. Two MDO formulations are applied to a sounding rocket in order to optimize the performance of the rocket. In the MDO of the referred vehicle, three disciplines have been considered, which are trajectory, propulsion and aerodynamics. A special design structure matrix is developed to assist data exchange between disciplines. This design process uses response surface method （RSM） for multidisciplinary optimization of the rocket. The RSM is applied to the design in two categories： the propulsion model and the system level. In the propulsion model, RSM determines an approximate mathematical model of the engine output parameters as a function of design variables. In the system level, RSM fits a surface of objective function versus design variables. In the first MDO problem formulation, two design variables are selected to form propulsion discipline. In the second one, three new design variables from geometry are added and finally, an optimization method is applied to the response surface in the system level in order to find the best result. Application of the first developed multidisciplinary design optimization procedure increased accessible altitude （performance index） of the referred sounding rocket by twenty five percents and the second one twenty nine.

关键词： multidisciplinary design optimization sounding rocket central composite design response surface method equation of motion of a rocket

Calculation of transient dynamic stress intensity factors at bimaterial interface cracks using a SBFEM-based frequency-domain approach

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Science China(Physics,Mechanics & Astronomy) 2008年第5期51卷 519-531页

作者： z.j.YANG A.j.DEEKS College of Civil Engineering and Architecture Zhejiang University School of Civil and Resource Engineering University of Western Australia

A frequency-domain approach based on the semi-analytical scaled boundary finite element method(SBFEM) was developed to calculate dynamic stress intensity factors(DSIFs) at bimaterial interface cracks subjected to transient ***-cause the stress solutions of the SBFEM in the frequency domain are analytical in the radial direction,and the complex stress singularity at the bimaterial interface crack tip is explicitly represented in the stress solutions,the mixed-mode DSIFs were calculated directly by *** complex frequency-response functions of DSIFs were then used by the fast Fourier transform(FFT) and the inverse FFT to calculate time histories of DSIFs.A benchmark example was *** re-sults were obtained by modelling the example with a small number of degrees of freedom due to the semi-analytical nature of the SBFEM.

关键词： scaled boundary finite element method bimaterial interface crack frequency domain dynamic stress intensity factors fast Fourier transform

Numerical investigation on the flowfield of “swallowtail” cavity for supersonic mixing enhancement

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Acta Mechanica Sinica 2009年第1期25卷 37-44页

作者： C. Wang z. jiang z. Hu j. Lu Institute or Mechanics. Chinese Academy of Sciences 100190 Beijing China ReCAPT Gyeongsang National University JinjuKyeongnam 660-701 South Korea

A ＂swallowtail＂ cavity for the supersonic combustor was proposed to serve as an efficient flame holder for scramjets by enhancing the mass exchange between the cavity and the main flow. A numerical study on the ＂swallow- tail＂ cavity was conducted by solving the three-dimensional Reynolds-averaged Navier-Stokes equations implemented with a k-e turbulence model in a multi-block mesh. Turbu- lence model and numerical algorithms were validated first, and then test cases were calculated to investigate into the mechanism of cavity flows. Numerical results demonstrated that the certain mass in the supersonic main flow was sucked into the cavity and moved spirally toward the combustor walls. After that, the flow went out of the cavity at its lateral end, and finally was efficiently mixed with the main flow. The comparison between the ＂swallowtail＂ cavity and the conventional one showed that the mass exchanged between the cavity and the main flow was enhanced by the lateral flow that was induced due to the pressure gradient inside the cavity and was driven by the three-dimensional vortex ring generated from the ＂swallowtail＂ cavity structure.

关键词： Supersonic mixing - Flame holder "Swallowtail" cavity - Combustion ignition Numerical simulation