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Flotation of Brazilian and Colombian Coals Using a Negative Bias

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j.urnal of Chemistry and Chemical Engineering 2013年第2期7卷 170-174页

作者： Irineu Brum H. Villegas W. Banguero j. guerrero C. Sampaio j. Barraza Laboratorio de Processamento Mineral Centro de Tecnologia Universidad Federal Rio Grande do Sul Porto Alegre Brasil Escuela de Ingenierla Quimica Universidad del Valle Cali 25360 Colombia

Brazil and Colombia have large reserves of coal. Those reserves in Brazil are located predominantly in the south and the main reserves in Colombia are located in the north. Despite the relative ease of exploitation, these resources have been underestimated as a source of energy. Currently, these countries are developing proj.cts and partnerships aiming to qualify this mineral resource, adding quality to the final product of the processing plants. In this scenario, the processing of Brazilian and Colombian coal in flotation columns appears as a promising alternative, having been successful in mineral systems containing fine particles. The paper aims to study the overall process of column flotation for a specific Brazilian coal and a specific Colombian coal. The material used in this study consists of fine coal from Brazil （Copelmi） and Colombia （Cerrej.n）. The obj.ctive is to recover carbonaceous matter and reduce the ash and contaminants grade. The two coals were floated using a negative bias in a 5 cm diameter conventional flotation column of 5 m high. Flotation parameter investigated included air velocity in the range 0.6 to 1.5 cm/s. For all runs, a constant negative bias of-0.25 cm/s and a pulp concentration of 8% w/w were used. For Cerrej.n coal, 300 g/ton of frother and 907 g/ton of collector was used, whereas for Copelmi coal, 600 g/ton of frother and 1,815 g/ton of collector was employed. The frother was a commercial Aerofroth 65 （AF65）, whereas the collector was Kerosene. For the Colombian coal, in general, yield, organic recovery, ash recovery and water recovery decreased with the increasing air rate. However, for Brazilian coal the air rate had no significant effect. For Colombian coal, the highest yield （60% w/w） and organic recovery （69% w/w） were obtained at the lowest air rate （0.6 cm/s）.

关键词： Negative bias column flotation coal.

Synthesis of coral-like structures of Pr-Yb co-doped YIG: Structural,optical, magnetic and antimicrobial properties

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j.urnal of Rare Earths 2024年第3期42卷 543-554,I0004页

作者： A.Fernandez Francisca P.Arauj. Y.Guerra S.Castro-Lopes j.Matilla-Arias Idglan S.de Lima Edson C.Silva-Filho j.sy A.Osaj.ma F.guerrero R.Pena-Garcia Federal University of Piau Graduate Program in Materials Science and EngineeringTeresinaPIBrazil Federal Rural University of Pernambuco Academic Unit of Cabo de Santo AgostinhoCabo de Santo AgostinhoPEBrazil Federal University of Piaui Department of PhysicTeresinaPBrazil Federal University of Pernambuco Graduate Program in Materials ScienceRecifePEBrazil University of Granma Departmentof Basic Sciences and Applied InformaticsFaculty of Technical SciencesBayamoCuba Federal University of Amazonas Department of PhysicManausAMBrazil Federal University of Pernambuco Department of PhysicRecifePEBrazil

Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDS) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.

关键词： Yttrium iron garnet(YIG) Coral-like structures Rare earths Band gap energy Magnetic properties Antimicrobial properties

Rotorcraft with a 3DOF Rigid Manipulator:Quaternion-based Modeling and Real-time Control Tolerant to Multi-body Couplings

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International j.urnal of Automation and computing 2018年第5期15卷 547-558页

作者： j.Alvarez-Munoz N.Marchand j.F.guerrero-Castellanos j.j.Tellez-Guzman j.Escareno M.Rakotondrabe Polytechnic Institute of Advanced Sciences FR 94200 ParisFrance Univ.Grenoble Alpes GIPSA-LabFR-38000 GrenobleFrance Autonomous University of Puebla(BUAP) Faculty of ElectronicsMX 72570 PueblaMexico University of Limoges ENSIL-ENSCI XLIM Laboratory UMR CNRS 7252Parc Ester Technopole16 rue AtlantisLimoges 87068France FEMTO-ST Institute UMR CNRS-UFC/ENSMM/UTBMAutomatic Control and Micro-Mechatronic DepartmentFR BesanconFrance

This paper proposes a simple solution for the stabilization of a mini-quadcopter carrying a 3DoF（degrees of freedom） manipulator robot in order to enhance its achievable workspace and application profile. Since the motion of the arm induces torques which degrade the stability of the system, in the present work, we consider the stabilization of both subsystems： the quadcopter and the robotic arm. The mathematical model of the system is based on quaternions. Likewise, an attitude control law consisting of a bounded quaternion-based feedback stabilizes the quadcopter to a desired attitude while the arm is evolving. The next stage is the translational dynamics which is simplified for control（nonlinear） design purposes. The aforementioned controllers are based on saturation functions whose stability is explicitly proved in the Lyapunov sense. Finally, experimental results and a statistical study validate the proposed control strategy.

关键词： Observer-based control quaternion and Newton-Euler modeling bounded-input control aerial manipulator disturbancerej.ction.

Epigenomics and gene regulation in mammalian social systems

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Current Zoology 2020年第3期66卷 307-319页

作者： Tania P.guerrero j.rns FICKEL Sarah BENHAIEM Alexandra WEYRICH Department Evolutionary Genetics Leibniz-Institute for Zoo and Wildlife Research(IZW)Alfred-Kowalke-Str.17BerlinD-10315Germany Faculty of Environment and Natural Resources Albert Ludwig University of FreiburgTennenbacher Str.4FreiburgD-79085Germany Instute for Biochemistry and Biology University of PotsdamKarl-Liebknecht-Str.2425Potsdam14476Germany Department Ecological Dynamics Leibniz-Institute for Zoo and Wildife Research(IZW)Alfred-Kowalke Str.17BerlinD-10315Germany

Social epigenomics is a new field of research that studies how the social environment shapes the epigenome and how in turn the epigenome modulates *** focus on describing known gene-environment interactions(GEIs)and epigenetic mechanisms in different mammalian social *** illustrate how epigenetic mechanisms integrate GEIs,we highlight examples where epigenetic mechanisms are associated with social behaviors and with their maintenance through neuroendocrine,locomotor,and metabolic *** discuss future research traj.ctories and open questions for the emerging field of social epigenomics in nonmodel and naturally occurring social ***,we outline the technological advances that aid the study of epigenetic mechanisms in the establishment of GEIs and vice versa.

关键词： epigenetics DNA methylation histone modification rank social status social systems

Synchronization of Robot Manipulators Actuated By Induction Motors with Velocity Estimator

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Computer Modeling in Engineering & Sciences 2019年第11期121卷 609-630页

作者： Felipe j.Torres Gerardo V.guerrero Carlos D.García Ricardo Zavala-Yoe Mario A.García Adolfo R.López University of Guanaj.ato Division of Engineering Campus Irapuato-SalamancaCarretera Salamanca-Valle de Santiago km 3.5+1.8GuanajuatoSalamanca36885México National Technological of Mexico/National Center of Research and Technological Development Av.Palmira S/N colonia PalmiraMorelosCuernavaca62490México School of Engineering and Sciences Monterrey TechnologicalPuente 222 Ejidos de HuipulcoCiudad de México14380México Superior Technological Institute of Irapuato Carretera Irapuato-Silao km 12.5GuanajuatoIrapuato36821México

A complete modeling(including the actuator dynamics)of a robot manipulator that uses three-phase induction motors is presented in this paper.A control scheme is designed to synchronize robot manipulators actuated by induction motors under a masterslave scheme in the case where the j.int velocity of the slave robots is *** of the research on the synchronization of robot manipulators assumes the use of ideal actuators to drive the j.ints;for that reason,in this work,a three-phase induction motor is considered to be a direct-drive actuator for each *** entire model of the mated system is obtained by a combination of the dynamics of the induction motor and robot ***,the synchronization control algorithm for a master-slave scheme in both the j.int space and workspace of robot manipulators driven by induction motors is *** observer based on the entire model is proposed to estimate the j.int velocity of the slave robot *** the Lyapunov criterion,a stability analysis of the synchronization control with a velocity estimator is *** analytical results show the synchronization and estimation errors are globally,uniformly,and ultimately *** with multiple robots demonstrate the performance of the proposed control algorithm.

关键词： Synchronization robot manipulator induction motor Lyapunov stability observer based on the model

A Three-Dimensional Range-Free Localization Algorithm Based on Mobile Beacons for Wireless Sensor Networks

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Computer Aided Drafting,Design and Manufacturing 2010年第1期20卷 83-92页

作者： guerrero E ALVAREZ j.RIVERO L School of Electronics and Information Engineering Beijing University of Aeronautics and Astronautics

In wireless sensor networks （WSNs） the position information of individual nodes is a matter of vital importance because allows the implementation of necessary network functions such as routing, querying and other applications. The obj.ctive of this paper is to propose an algorithm of three-dimensional distributed range-free localization for WSNs, using a mobile beacon （MB） equipped with a rotary and tilting directional antenna. This algorithm, denominated as the three-dimensional azimuthally defined area localization algorithm （3D- ADAL）, is executed in each sensor node and is based only on the analysis of the information received from the MB, therefore is energy efficient and contributes to extend the lifetime of the sensor network. Additionally the proposed algorithm has the advantage of being simple and economical. The simulation results show that the proposed algorithm is a practical, effective and accurate method for a three-dimensional location of sensor nodes in a WSN.

关键词： 3D localization wireless sensor network mobile beacon directional antenna

Redundancy Ring Design for Transponder Subsystem in the VX-SAT Communication Satellite

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Computer Aided Drafting,Design and Manufacturing 2010年第1期20卷 46-55页

作者： guerrero E ALVAREZ j.RIVERO L School of Electronics and Information Engineering Beijing University of Aeronautics and Astronautics

Modem communications is an indispensable tool for modem social economy and modem social life. The payload of a communication satellite provides radio relay for links between earth stations. With most commercial communication satellites the payload consists of two distinct parts with well defined interfaces： the repeater and the antennas. The repeater designates the electronic equipment which performs a range of functions on the signals from the receiving antenna before delivering them to the transmitting antenna. The VX-SAT proj.ct is a system engineering exercise, realized in the China Academy of Space Technology （CAST） with the obj.ctive of training the persons in charge of designing futures communication satellites in the Bolivarian Agency of Space Activities （ABAE） in Venezuela. This paper includes an overview of the VX-SAT system, the preliminary design of the communications payload and finally the method used to design the redundancy ring of the transponder subsystem.

关键词： communication satellite payload Ku-band redundancy ring

NUMERICAL SOLUTION OF DIFFERENTIAL EQUATIONS IN IRREGULAR PLANE REGIONS USING QUALITY STRUCTURED CONVEX GRIDS

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International j.urnal of Modeling, Simulation, and Scientific Computing 2013年第2期4卷 115-129页

作者： F.DOM´INGUEZ-MOTA P.FERNANDEZ-VALDEZ S.MENDOZA-ARMENTA G.TINOCO-guerrero j.G.TINOCO-RUIZ Facultad de Ciencias F´ısico Matem´aticas Universidad Michoacana de San Nicol´as de Hidalgo Edificio“B” Ciudad Universitaria C.P.58040MoreliaMexico

The variational grid generation method is a powerful tool for generating structured convex grids on irregular simply connected domains whose boundary is a polygonal j.rdan *** examples that show the accuracy of a finite difference approximation to the solution of a Poisson equation using this kind of structured grids have been recently *** this paper,we compare the accuracy of the numerical solution calculated using those structured grids and finite differences against the solution obtained with Delaunay-like triangulations on irregular regions.

关键词： Numerical grid generation direct generation method finite difference method finite element method Delaunay triangulation.

Comparison between type-2 and type-1 myocardial infarction：clinical features, treatment strategies and outcomes

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j.urnal of Geriatric Cardiology 2016年第1期13卷 15-22页

作者： Angel Lopez-Cuenca Miriam Gomez-Molina Pedro j.Flores-Blanco Marianela Sanchez-Martinez Andrea Garcia-Narbon Ignacio De Las Heras-Gomez Maria j.Sainchez-Galian Esther guerrero-Perez Mariano Valdes Sergio Manzano-Femandez Department of Internal Medicine Hospital de la Vega Lorenzo Guirao Cieza Spain Division of Cardiology University Hospital Virgen de la Arrixaca School of Medicine IMIB Murcia Spain Department of Biochemistry University Hospital Virgen de la Arrixaca School of Medicine IMIB Murcia Spain Department of lnternal Medicine University of Murcia Murcia Spain

Obj.ctive To assess the differences in incidence, clinical features, current treatment strategies and outcome in patients with type-2vs. type-1 acute myocardial infarction （AMI）.Methods We included 824 consecutive patients with a diagnosis of type-1 or type-2 AMI. Dur-ing index hospitalization, clinical features and treatment strategies were collected in detail. At 1-year follow-up, mortality, stroke, non-fatal myocardial infarction and maj.r bleeding were ***-1 AMI was present in 707 （86%） of the cases while 117 （14%） were classified as type-2. Patients with type-2 AMI were more frequently female and had higher co-morbidities such as diabetes, previous non-ST segment elevation acute coronary syndromes, impaired renal function, anaemia, atrial fibrillation and malignancy. However, preserved left ventricular ej.ction fraction and normal coronary arteries were more frequently seen, an invasive treatment was less common, and anti-platelet medications, statins and beta-blockers were less prescribed in patients with type-2 AMI. At 1-year follow-up, type-2 AMI was associated with a higher crude mortality risk （HR： 1.75, 95% CI： 1.14-2.68;P = 0.001）, but this association did not remain significant after multivariable adj.stment （P = 0.785）. Furthermore, we did not find type-2 AMI to be associated with other clinical *** In this real-life population, compared with type-1, type-2 AMI were predominantly women and had more co-morbidities. Invasive treatment strategies and cardioprotective medications were less used in type-2, while the 1-year clinical outcomes were similar.

关键词： Coronary vessels Follow-up studies Myocardial infarction