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Parametric study of electrostatic separation of South African fine coal

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Mining Science and Technology 2010年第4期20卷 535-541页

作者： BADA Samson TAO Daniel HONAKER Rick falcon Lionel falcon Rosemary School of Chemical and Metallurgical Engineering Faculty of Engineering and the Built Environment University of the Witwatersrand department of Mining Engineering University of Kentucky

The fact that water requirements are a major problem for present and future developments in material beneficiation, and the construction of a new power plant in South Africa, forms the basis for the utilization of a Rotary Triboelectrostatic Separator (RTS) for beneficiation of South African pulverized coal. The cleaning potential of Majuba and Koorfontein coal was first evaluated using kinetic froth flotation tests on the -177 μm coal fraction. The RTS tests were conducted under varied process parameters. Parameters such as applied separating voltage, air injection velocity, particle feed rate and splitter position were investigated. Two stage separation results show that the RTS reduced Majuba coal initially containing about 30% ash to a clean product of 14.30%, or 19.46%, ash at a combustible recovery of 15.10%, or 53.02%, respectively. Similar separation performance was also achieved with the Koorfontein coal. The mineral and organic compositions in the feed, after single stage and after the second stage separations were characterized using X-ray diffraction analysis. The results show a better separation for the second stage coal products.

关键词： coal cleaning particle charging RTS technique separation stage

Electrostatic concentration of phosphate flotation concentrate

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International Journal of Mining Science and Technology 2013年第3期23卷 403-406页

作者： Bada Samson Gcanga Sandi falcon Lionel falcon Rosemary Makhula Mpho School of Chemical and Metallurgical Engineering Faculty of Engineering and the Built Environment University of the Witwatersrand department of Mineral Processing Mintek Randburg 2125 South Africa

The concentration of phosphate flotation concentrate with P2O5 grade lower than the commercially acceptable phosphate quality was upgraded in the use of tribo-electrostatic technique. The concentration of the flotation concentrate stream was conducted under both triboelectrification and inductive charging mechanism. Mineralogical analysis reveals that the phosphate ore utilized was dominated mainly by fluorapatite, crandallite, wavellite, and with quartz as the major gangue mineral. Flotations concentrate of about 28.87% P2O5 was obtained from the reverse flotation technique, after conditioning the phosphate ore at 80% passing 150 lm under Lilafloat. Constant parameters such as à6 kV charging voltage, 25 kV separating voltage, inlet air, different charger rotary speed and splitter distances were investigated. Commercially accepted grade of 35.50% P2O5 was attained after the second stage of separation with a recovery of 12.26%, another phosphate product of 34.02% P2O5 and 85.19% was also recovered under the same condition. Single stage of separation also shows a significant increase in the grade of the product obtained, with 33.41% P2O5 and 84.07% recovery achievable. The practicability of tribo-electrostatic separation technique for upgrading flotation concentrates resulted in a significant increase in grade for de.

关键词： Dry beneficiation Fluorapatite-phosphate Mineralogy Reverse flotation Triboelectrostatic

Regulatory role of NFAT1 signaling in articular chondrocyteactivities and osteoarthritis pathogenesis

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BIOCELL 2023年第10期47卷 2125-2132页

作者： MINGCAI ZHANG TANNER CAMPBELL SPENCER falcon JINXI WANG Harrington Laboratory for Molecular Orthopedics Department of Orthopedic SurgeryUniversity of Kansas Medical CenterKansas CityUSA

Osteoarthritis (OA), the most common form of joint disease, is characterized clinically by joint pain, stiffness,and deformity. OA is now considered a whole joint disease;however, the breakdown of the articular cartilage remains themajor hallmark of the disease. Current treatments targeting OA symptoms have a limited impact on impeding orreversing the OA progression. Understanding the molecular and cellular mechanisms underlying OA development isa critical barrier to progress in OA therapy. Recent studies by the current authors’ group and others have revealedthat the nuclear factor of activated T cell 1 (NFAT1), a member of the NFAT family of transcription factors, regulatesthe expression of many anabolic and catabolic genes in articular chondrocytes of adult mice. Mice lacking NFAT1exhibit normal skeletal development but display OA in both appendicular and spinal facet joints as adults. Thisreview mainly focuses on the recent advances in the regulatory role of NFAT1 transcription factor in the activities ofarticular chondrocytes and its implication in the pathogenesis of OA.

关键词： Osteoarthritis Chondrocyte NFAT1 Transcription factor Regulation of gene expression

Experimental evaluation of activated carbon derived from South Africa discard coal for natural gas storage

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International Journal of Coal Science & Technology 2019年第3期6卷 459-477页

作者： Jibril Abdulsalam Jean Mulopo Bilainu Oboirien Samson Bada Rosemary falcon Sustainable Energy and Environment Research Group School of Chemical and Metallurgical Engineering University of the Witwatersrand Private Bag X3 Johannesburg WITS 2050 South Africa Clean Coal and Sustainable Energy Research Group Faculty of Engineering and the Built Environment University of the Witwatersrand Private Bag X3 Johannesburg WITS 2050 South Africa department of Chemical Engineering University of Johannesburg Doomfontein Johannesburg 2028 South Africa

Lacking in literature is the use of discard coal to produce activated carbon and in its subsequent use in the storage of natural gas. In this study, the characterization and gas storage evaluation of a largely porous activated carbon with large surface area synthesized from discard coal were investigated. Discard coals are waste material generated from coal beneficiation process. In developing the activated carbon, chemical activation route with the use of KOH reagent was applied. The effects of KOH/discard coal weight ratio (1:1, 2.5:1, 4:1), temperature (400-800 ℃) and particle size (0.15-0.25 mm, 0.25-0.5 mm, 0.5-1 mm) on the adsorptive properties of the activated carbon were methodically evaluated and optimized using response surface methodology. The synthesized activated carbon was characterized using BET, SEM/EDS, and XRD. The results showed that for each activation process, the surface area and pore volume of the resulting activated carbon increased with increased temperature and KOH/discard coal weight ratio. The maximum surface area of 1826.41 m2/g, pore volume of 1.252 cm^3/g and pore size of 2.77 nm were obtained at carbonization temperature of 800 ℃ and KOH/discard coal weight ratio of 4:1. Methane and nitrogen adsorption data at high pressure were fitted to Toth isotherm model with a predictive accuracy of about 99%. Adsorption parameters using the Toth model provides useful information in the design of adsorbed natural gas storage system. According to the requirements of adsorbent desired for natural gas storage, it could be stated that the synthesized activated carbon could well be applied for natural gas storage.

关键词： Discard coal Activated carbon Surface area Methane Adsorption

Relationships between Some <i>k</i>-Fibonacci Sequences

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Applied Mathematics 2014年第15期5卷 2226-2234页

作者： Sergio falcon department of Mathematics University of Las Palmas de Gran Canaria Las Palmas de Gran Canaria Spain

In this paper, we will see that some k?-Fibonacci sequences are related to the classical Fibonacci sequence of such way that we can express the terms of a k -Fibonacci sequence in function of some terms of the classical Fibonacci sequence. And the formulas will apply to any sequence of a certain set of k'?-Fibonacci sequences. Thus we find k -Fibonacci sequences relating to other k -Fibonacci sequences when?σ'k?is linearly dependent of?.

关键词： Fibonacci and Lucas Numbers k -Fibonacci Numbers Pascal Triangle

Statistical analysis and concentration of iron ore using Longi LGS 500 WHIMS

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矿业科学技术学报：英文版 2016年第5期26卷 769-775页

作者： Makhula M.J. falcon R.M.S. Bergmann C.P. Bada S.O. department of Mineral Processing Division Mintek Johannesburg 2125 South Africa School of Chemical and Metallurgical Engineering University of the Witwatersrand Johannesburg 2050 South Africa

A Longi LGS 500 wet high intensity magnetic separator(WHIMS) was used to concentrate a fine, low grade South African hematite ore. The ore was prepared into different size fractions and was subjected to changes in pulp density, magnetic field intensity and pulsation frequency which followed a 33 full factorial matrix. The concentrate mass yield and Fe grade were selected as the dependent responses to the changes. The analysis of variance(ANOVA) shows that the variables investigated are significant to the material's response to magnetic separation. This significance was in the order of magnetic field intensity followed by pulsation frequency and then pulp density. It was also noted that a single stage magnetic separation has a potential to upgrade a feed( 75 lm and 40% Fe) to a 55% Fe grade, as the pulsation frequency increases. In addition, the model predictions and actual data were in good agreement, reporting regression coefficients within acceptable ranges.

关键词： Magnetic separation Longi LGS 500 Hematite ANOVA

On the k–Lucas Numbers of Arithmetic Indexes

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Applied Mathematics 2012年第10期3卷 1202-1206页

作者： Sergio falcon department of Mathematics and Institute for Applied Microelectronics (IUMA) University of Las Palmas de Gran Canaria (Spain)

In this paper, we study the k–Lucas numbers of arithmetic indexes of the form an+r , where n is a natural number and r is less than r. We prove a formula for the sum of these numbers and particularly the sums of the first k-Lucas numbers, and then for the even and the odd k-Lucas numbers. Later, we find the generating function of these numbers. Below we prove these same formulas for the alternated k-Lucas numbers. Then, we prove a relation between the k–Fibonacci numbers of indexes of the form 2rn and the k–Lucas numbers of indexes multiple of 4. Finally, we find a formula for the sum of the square of the k-Fibonacci even numbers by mean of the k–Lucas numbers.

关键词： k–Fibonacci Numbers k–Lucas Numbers Generating Function

From"planning in section"to"semiduplex":The New Humanism and the alternate-corridor technique

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Frontiers of Architectural Research 2020年第3期9卷 485-497页

作者： Alejandro Perez-Duarte Fernandez Jose Manuel falcon Meraz School of Architecture and design Instituto Tecnologico y de Estudios Superiores de Occidente45604TlaquepaqueJaliscoMexico

Most of the pretending innovative modern housing projects show a common element that can be perceived when looking at the cross-section,evidencing the use of alternate corridors,which was recognized as a projective technique under Wells Coates expression"Planning in Section".Contrasting virtues concerning the resulting space were observed at different historical *** late 19th Century used it to create *** modern architecture used it to increase efficiency,where flexibility was ***,during the’60s,the alternative corridor technique started to be used to attend social issues,popularizing the split-level term,and echoing 19th Century privacy *** like Smithson’s"doorstep"and Candilis"semi-duplex"section reveal their ***-differentiated areas(public/intimate/col-lective)and socially controlled areas were obtained in domestic interiors with a few steps,creating singular spaces where children can play while being monitored by ***-duplex geometry showed new adaptability to different profiles:a small kitchenless apartment for a bachelor could be inserted aside from a larger two-level family *** paper shows an overview of this projective technique by contrasting different housing *** similar split-level geometries seem to have been coming back recently,questions about it are necessary.

关键词： Alternate corridor split-level housing Privacy duplex

Full Euclidean Algorithm by Means of a Steady Walk

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Applied Mathematics 2021年第4期12卷 269-279页

作者： Carlos M. falcon Rodriguez Maria A. Garcia Cruz Claudia falcon Grupo de Investigación de Análisis Matemático Instituto de Formación docente Salomé Ure&#241 a Santo Domingo D.N. República Dominicana Wake Forest University Winstom-Salem NC USA

Let x and y be two positive real numbers with x y. Consider a traveler, on the interval [0, y/2], departing from 0 and taking steps of length equal to x. Every time a step reaches an endpoint of the interval, the traveler rebounds off the endpoint in order to complete the step length. We show that the footprints of the traveler are the output of a full Euclidean algorithm for x and y, whenever y/x is a rational number. In the case that y/x is irrational, the algorithm is, theoretically, not finite;however, it is a new tool for the study of its irrationality.

关键词： Extended Euclidean Algorithm Greatest Common Divisor Incommensurable Numbers Steady Walk Diophantine Equation