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Mineral sulphide-lime reactions and effect of CaO/C mole ratio during carbothermic reduction of complex mineral sulphides

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International Journal of Minerals,Metallurgy and Materials 2014年第1期21卷 1-11页

作者： Yotamu stephen Rainford Hara Institute for Materials Research(IMR) School of ProcessEnvironmental and Materials Engineering(SPEME)University of Leeds

Mineral sulphide （MS）-lime （CaO） ion exchange reactions （MS ＋ CaO = MO ＋ CaS） and the effect of CaO/C mole ratio during carbothermic reduction （MS ＋ CaO ＋ C = M ＋ CaS ＋ CO（g）） were investigated for complex froth flotation mineral sulphide concentrates. Phases in the partially and fully reacted samples were characterised by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The primary phases during mineral sulphide-lime ion exchange reactions are Fe304, CaSO4 Cu2S, and CaS. A complex liquid phase of Ca2CuFeO3S forms during mineral sulphide-lime exchange reactions above 1173 K. The formation mechanisms of Ca2CuFeO3S liquid phase are determined by characterising the partially reacted samples. The reduction rate and extent of mineral sulphides in the presence of CaO and C increase with the increase in CaO/C ratio. The metallic phases are surrounded by the CaS rich phase at CaO/C 〉 1, but the metallic phases and CaS are found as separate phases at CaO/C 〈 1. Experimental results show that the stoichiometric ratio of carbon should be slightly higher than that of CaO. The reactions between CaO and gangue minerals （SiO2 and A1203） are only observed at CaO/C 〉 1 and the reacted samples are excessively sintered.

关键词： sulphide minerals ion exchange carbothermic reduction lime

A new hadron spectroscopy

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Frontiers of physics 2015年第2期10卷 1-34页

作者： stephen Lars Olsen Center for Underground Physics Institute of Basic Science Daejeon 305-811 Korea

QCD-motivated models for hadrons predict an assortment of ＂exotic＂ hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons： the six-quark H-dibaryon~ and tetraquark, hybrid and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have been identified. On the other hand, a number of meson states, one that seems to be a proton-antiproton bound state, and others that contain either charmed- anticharmed quark pairs or bottom-antibottom quark pairs, have been recently discovered that neither fit into the quark-antiquark meson picture nor match the expected properties of the QCD- inspired exotics. Here I briefly review results from a recent search for the H-dibaryon, and discuss some properties of the newly discovered states -the proton-antiproton state and the so-called XYZ mesons- and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.

关键词： quarks charmonium pentaquarks di-baryons baryonium tetraquarks

Labechia carbonaria Smith 1932 in the Early Carboniferous of England;affinity,palaeogeographic position and implications for the geological history of stromatoporoid-type sponges

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Journal of Palaeogeography 2021年第1期10卷 1-18页

作者： stephen Kershaw Consuelo Sendino Department of Life Sciences Brunel University LondonKingston LaneUxbridge UB83PHUK Department of Earth Sciences Natural History MuseumCromwell RoadLondon SW75BDUK

Stromatoporoid sponges were very abundant during the middle Palaeozoic Era and are thought to disappear at the end of the Devonian Period in the Hangenberg Crisis. However, there are records of organisms with stromatoporoid-type structure in Carboniferous strata, the subject of this study. The Viséan fossil Labechia carbonaria Smith 1932 has been discussed previously in literature and its affinity has not been confirmed. In this study, the type material of L. carbonaria collected from the middle part of the Frizington Limestone Formation(previously called Seventh Limestone), Holkerian Substage, stored in the Natural History Museum(London, UK) and British Geological Survey(Keyworth, UK) was re-examined. The Holkerian Substage, in which L. carbonaria was found, lies between ca 335–339 Ma, and the Frizington Limestone Formation ranges from topmost Arundian to upper Holkerian, so middle Frizington Limestone Formation is likely approximately 337 Ma. L. carbonaria comprises thick long pillars connected by thin curved cyst plates consistent with the structure of the stromatoporoid genus Labechia. However, a common opinion is that L. carbonaria fossils may be mistaken for fragments of rugose corals,but there are problems with assigning it to the Rugosa. In vertical section(VS) L. carbonaria could be mistaken for a transverse section(TS) of a Carboniferous rugose coral. However, in TS L. carbonaria shows the rounded cross sections of stromatoporoid pillars. If it was a coral, septal sheets of the VS of a coral should be seen. For a rugose affinity to still apply, a coral structure would have to be composed of free trabeculae, but these are not known after the middle of the Devonian Period;there are no corals of Early Carboniferous age with the structure of ***. Another interpretation, that L. carbonaria is a chaetetid, is discounted because it lacks calicles and is very different in structure from chaetetids. We conclude that L. carbonaria is a stromatoporoid. Becau

关键词： Stromatoporoids Holkerian Viséan Carboniferous Rugosa Labechia carbonaria Labechia conferta

Groundwater--sustainability issues and governance needs

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Episodes 2006年第4期29卷 238-243页

作者： stephen Foster IAH President World Bank GW-MATE Director

This paper provides a global overview of groundwater resource sustainability concerns and corresponding governance （management and protection） requirements, with special emphasis on the developing world and on Asia in particular. It is based on an opening plenary address to the International Association of Hydrogeologists （IAH） 34th Congress on the theme ＇Groundwater-- Present Status ＆ Future Tasks＇, celebrated in Beijing, China in the year of the IAH 50th Anniversary on 9 October 2006.

关键词：地下水资源资源管理可持续发展灌溉农业水供应

Combining solar power with coal-fired power plants,or cofiring natural gas

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Clean Energy 2018年第1期2卷 1-9页

作者： stephen Mills IEA Clean Coal Centre Apsley House176 Upper Richmond RoadLondon SW152SHUK

Coal-fired power operators continue to look for ways to increase the efficiency and extend the working lives of their plants by improving operational flexibility and reducing environmental *** possible options are explored here:combining solar energy with coal-fired power generation,and cofiring natural gas in coal-fired *** techniques show *** on the individual circumstances,both can increase the flexibility of a power plant whilst reducing its *** some cases,plant costs could also be ***,any solar-based system is limited geographically to locations that receive consistently high levels of solar ***,although many coal-fired plants already burn limited amounts of gas alongside their coal feed,for cofiring at a significant level,a reliable,affordable supply of natural gas is *** is not the case *** for each technology,there are niche and mainstream locations where the criteria can be *** need for good solar radiation means that the uptake of coal-solar hybrids will be *** natural gas has wider potential:currently,the largest near-term market appears to be for application to existing coal-fired plants in the ***,where gas is available and affordable,potential markets also exist in some other countries.

关键词： coal-fired power plant coal-solar hybrid power generation solar power cofiring hybrid

The Power Allocation Game on A Network:A Paradox

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IEEE/CAA Journal of Automatica Sinica 2018年第4期5卷 771-776页

作者： Yuke Li A.stephen Morse the department of political science yale university ieee the department of electrical engineering yale university

The well-known Braess paradox in congestion games states that adding an additional road to a transportation network may increase the total travel time, and consequently decrease the overall efficiency. This paper presents a paradox in a similar spirit and involves a distributed resource allocation game on networks, namely the power allocation game between countries developed in Li and Morse(2017). The paradox is that by having additional friends may actually decrease a country's total welfare in equilibrium. Conditions for this paradox to occur as well as the price of anarchy results are also derived.

关键词： Friends paradox price of anarchy resource allocation game success survival utility

SEMI-QUANTITATIVE CHARACTERIZATION OF SEGMENT DISTRIBUTION IN LLDPE BASED ON THERMAL SEGREGATION

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Chinese Journal of Polymer Science 2002年第4期20卷 347-352页

作者： stephen Z.D.Cheng Maurice Morton Institute and Department of Polymer Science University of Akron Akron Lhio 44325-3909 USA

Based on successive multiple-step isothermal crystallization and self-nucleation annealing methods, a novel semi-quantitative method for the characterization of segment distribution in linear low density polyethylene (LLDPE) was established by treating the thermal analysis data using the Gibbs-Thomson equation. The method was used to describe the segment distribution of Ziegler-Natta catalyzed LLDPE (Z-N LLDPE), metallocene catalyzed LLDPE (m-LLDPE) and two commercial LLDPEs with wide molecular weight distribution. The differences of the results obtained from the two thermally treated samples were compared. The results of segment distribution of the polymers were discussed according to their microstructure data and were compared with their characteristics. It can be deduced from the results that this characterization method is effective to characterize the sequence structure of the branched ethylene copolymers.

关键词： characterization segment distribution linear low density polyethylene thermal segregation

Laplace plane and low inclination geosynchronous radar mission design

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Science China(Information Sciences) 2017年第6期60卷 62-71页

作者： stephen HOBBS Joan Pau SANCHEZ School of Aerospace Transport and Manufacturing Cranfield University

This study is inspired by the Laplace orbit plane property of requiring minimal station-keeping and therefore its potential use for long-term geosynchronous synthetic aperture radar(GEOSAR) imaging. A set of GEOSAR user requirements is presented and analysed to identify significant mission requirements. Imaging geometry and power demand are assessed as a function of relative satellite speed(which is determined largely by choice of orbit inclination). Estimates of the cost of station-keeping as a function of orbit inclination and right ascension are presented to compare the benefits of different orbit choices. The conclusion is that the Laplace plane(and more generally, orbits with inclinations up to 15°) are attractive choices for GEOSAR.

关键词： Laplace plane station-keeping geosynchronous inclination GEOSAR

On Iterative Algorithm and Perturbation Analysis for the Nonlinear Matrix Equation

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Communications on Applied Mathematics and Computation 2022年第3期4卷 1158-1174页

作者： Chacha stephen Chacha Department of Mathematics Physics and InformaticsMkwawa University College of EducationP.O.Box 2513IringaTanzania

In this study,an iterative algorithm is proposed to solve the nonlinear matrix equation X+A∗eXA=*** expressions for mixed and componentwise condition numbers with their upper bounds are derived to measure the sensitivity of the considered nonlinear matrix *** analysis for the derived condition numbers and the proposed algorithm are *** proposed iterative algorithm reduces the number of iterations significantly when incorporated with exact line *** condition number seems more reliable to detect the sensitivity of the considered equation than mixed condition number as validated by numerical examples.

关键词： Mixed condition number Componentwise condition number Iterative algorithm Perturbation analysis Exact line search