Variabilidade espacial de atributos físicos de um latossolo vermelho-amarelo, sob lavoura cafeeira

O conhecimento da variabilidade dos atributos físicos do solo é importante para o monitoramento da qualidade do solo, pois eles estão diretamente relacionados com a sustentabilidade da produção agrícola. Este estudo teve como objetivos avaliar e identificar as estruturas de dependência espacial, por meio da construção de semivariogramas, num Latossolo Vermelho-Amarelo (LVA), sob lavoura cafeeira; caracterizar as distribuições espaciais dos atributos físicos pela krigagem ordinária; e identificar a camada com maior impedimento físico. O experimento foi conduzido num LVA textura muito argilosa na Fazenda da Empresa de Pesquisa Agropecuária de Minas Gerais, em Patrocínio, MG. A amostragem foi realizada em trincheiras confeccionadas nas intersecções de uma malha retangular de 40 x 150 m, perfazendo um total de 28 pontos, de onde foram coletadas amostras indeformadas em anéis metálicos de 2,54 cm de altura e 6,30 cm de diâmetro, com auxílio do amostrador tipo Uhland. Cada trincheira possuía três degraus de 2,0 x 1,5 m de superfície, nas camadas de 0,00; 0,10; e 0,25 m, onde se coletaram sete amostras indeformadas em cada degrau, dispostas em forma matricial, totalizando 588 amostras. Os atributos físicos do solo apresentaram estrutura de dependência espacial em todas as camadas, exceto a porosidade total. A técnica de krigagem ordinária demonstrou ser alternativa viável para a estimativa de dados em pontos não amostrados na área experimental. A camada de 0,00-0,03 m apresentou maior impedimento físico ao crescimento de raízes, por apresentar maior densidade e menor macroporosidade do solo

A Hybrid Method Combining Static And Full Wave Techniques To Solve Conducted Emissions Problems

Frequency dependent models are required to address most of the conducted emissions problems when any circuit or system simulator is used. High frequency 3D full wave solvers are often employed to extract S parameters from passive components, generating a frequency dependent model, which in this case, is known as a Touchstone file format. This extraction process uses a numerical technique to solve the complete set of Maxwell's equation for higher frequencies and then extrapolates the results at DC. This work presents a methodology that uses a static solver to actually calculate the DC resistance at 0Hz, yielding a more accurate S parameter matrix of the model. A commercial washing machine is used as an example for a conducted emissions analysis (according to CISPR 14-1). Measurements results are also presented, showing a reasonably good match with the proposed technique. © 2013 IEEE.277281Taflove, A., Hagness, S.C., (2005) Computational Electrodynamics: The Finite-Difference Time-Domain Method, 3rd Ed, , Artech House Publishers, ISBN 1-58053-832-0Bhobe, A.U., Holloway, C.L., Piket-May, M.J., Meander delay line challenge problem: A comparison using FDTD, FEM and MoM (2001) 2001 IEEE Int. Symp. on EMC, 2, pp. 805-810Dyczlj-Edllnger, R., Peng, G., Lee, J.F., Efficient finite element solvers for the Maxwell equations in the frequency domain (1999) Comput. Methods Appl. Mech. Eng., 169 (34), p. 297309. , FebLee, S., Mao, K., Jin, J., A complete finite element analysis of multilayer anisotropic transmission lines from DC to terahertz frequencies (2008) IEEE Trans. Advanced Packaging, 31, pp. 326-338. , 2, MayLee, S.C., Lee, J.F., Lee, R., Hierarchical vector finite elements for analyzing waveguiding structures (2003) IEEE Trans Microwave Theory Tech, 51 (8), p. 18971905. , AugZhu, J., Jiao, D., A unified finite-element solution from zero frequency to microwave frequencies for full-wave modeling of large-scale three-dimensional on-chip interconnect structures (2008) IEEE Trans. Advanced Packaging, 31 (4), pp. 873-881. , NovZhu, J., Jiao, D., A theoretically rigorous full-wave finite-element-based solution of Maxwell's equations from DC to high frequencies (2010) ECE Technical Reports, Paper, 395Lee, S., Jin, J., Application of the tree-cotree splitting for improving matrix conditioning in the full-wave finite-element analysis of highspeed circuits (2008) Microwave and Optical Technology Letters, 50 (6), pp. 1476-1481. , June(2012), http://www.ansys.com/Products/Simulation+Technology/Electromagnetics/ High-Performance+Electronic+Design/ANSYS+HFSS, ANSYS HFSS website. [Online]. Available(2012), http://www.ansys.com/Products/Simulation+Technology/Electromagnetics/ High-Performance+Electronic+Design/ANSYS+Q3D+Extractor, ANSYS Q3D Extractor website. [Online]. AvailableMologni, J.F., Alves, M.A.R., Braga, E.S., Numerical study on performance of pyramidal and conical isotropic etched single emitters (2006) Microelec. Journal, 37, pp. 152-157Young, B., Wide-band 2N-port S-parameter extraction from N-port data (1998) IEEE Trans. Microwave and Theory Techniques, 46 (9), pp. 1324-1327Deschrijver, D., DC-preserving passivity enforcement for S-parameter based macromodels (2010) IEEE Trans. Microwave and Theory Techniques, 58 (4), p. 397Paul, C.R., (2006) Introduction to Electromagnetic Compatibility, , 2nd ed. John Wiley & Sons, ISBN-13: 978-0-471-75500-

Investigating Gsm Interference In Automotive Sound Systems Using State Of The Art Electromagnetic Simulation

EMI (Electromagnetic Interference) is one of the major concerns today in the automotive industry. The main reason is that vehicles are using and depending more on electronic technology. The causes of electromagnetic interference problems are not only related to the ever-increasing number of embedded electronics systems in vehicles, but also to external electronic devices that are brought in to automobiles by drivers and passengers (e.g. cell phone, MP3 players, Bluetooth devices, portable video games). Even though these problems can cause serious issues on safety systems like the airbag, their symptoms are often noticed in a less harm way in the sound system. A very common EMI problem in automotive sound systems is a particular noise caused by devices that uses GSM (Global System for Mobile Communications) technology. Most of the cell phones and vehicle locators rely on GSM technology. In Brazil there is a national normative known as Contran 245, which when issued, will enforce the use of locators on all vehicles commercialized in Brazil. Hence, EMI problems caused by GSM technology will likely to be noticed more often in Brazil. GSM devices emit short duration RF (Radio Frequency) pulses at a rate of 217Hz. The interference pulses contain the fundamental frequency plus a large number of harmonics that overlaps the frequency range of listening, which goes up to 20kHz. This work presents a detailed study of the EMI of GSM devices in automotive sound systems using state of the art numerical simulation technology provided by ANSYS HFSS and ANSYS Designer tools. A system model comprising a vehicle with a complete sound system, wiring harness and GSM devices communicating to a base station GSM tower is used for this analysis. Measurement data is also presented showing a good match to the simulated results. Options to decrease the GSM interference and overcome this issue are also discussed. © 2013 SAE INTERNATIONAL.13Devereux, R.W., Archambeault, B., Fuller, G.L., Assessment of analytical codes for use in modeling aircraft onboard EMI threats (1997) AIAA/IEEE 16th Digital Avionics Systems Conference, pp. 17-24. , Irvine, CAPerry, T.S., Geppert, L., Do portable electronics endanger flight? The evidence mounts (1996) IEEE Spectrum, 33, pp. 26-33Strauss, B., Avionics interference from portable electronic devices: Review of the Aviation Safety Reporting System database (2002) Proceeding of the 21st Digital Avionics Systems Conference, 2, pp. 13E31-13E38Mologni, J., A Time-Frequency Domain Analysis of Crosstalk Phenomenon on LIN/CAN Based Architectures (2008) SAE Technical Paper Series, Paper 2008-36-0046, , ","Vouvakis, M.N., Zhao, K., Seo, S.M., Lee, J.-F., A Domain Decomposition Approach for Non-Conformal Couplings between Finite and Boundary Elements for Unbounded Electromagnetic Problems in R3 (2007) J. Comput. Phys., 225 (1), pp. 975-994Zhao, K., Rawat, V., Lee, S.-C., Lee, J.-F., A Domain Decomposition Method with Non-Conformal Meshes for Finite Periodic and Semi-Periodic Structures (2007) IEEE Trans. Antennas Propag., 55 (9), pp. 2559-2570Zhao, K., Rawat, V., Lee, J.-F., A Domain Decomposition Method for Electromagnetic Radiation and Scattering Analysis of Multi-Target Problems (2008) IEEE Trans. Antennas Propag., 56 (8), pp. 2211-2221Harrington, R.F., Field computation by moment methods (1993) IEEE Series on Electromagnetic Waves, , New YorkCangellaris, A.C., Lee, R., The bymoment methods for two-dimensional electromagnetic scattering (1990) IEEE Trans. Antennas Propag., 38 (9), pp. 1429-1437Silvestro, J., Zhao, K., Sligar, A., Hybrid Finite Element-Boundary Integral Technique for Efficient Simulation of Radiation and Scattering (2011) Microw. J., 54 (1), p. 74. , JanZhao, K., Vouvakis, M.N., Lee, J.-F., Solving Electromagnetic Problems Using A Novel Symmetric FEM-BEM Approach (2006) IEEE Trans. Mag., 42 (4), pp. 583-587. , Ap

Automotive Emc Analysis Using The Hybrid Finite Element Boundary Integral Approach

The majority of innovative trends in automotive industry today relies on electronic systems. Understanding the electromagnetic behavior of the electronic control units (ECUs) in a vehicle has become an ever increasing concern of automotive manufacturers. Computational Electromagnetic Modeling (CEM) is a cost effective approach that has being adopted by the automotive industry to address electromagnetic compatibility (EMC) problems. Automotive structures are electrically large in nature and the systems required for a complete EMC analysis can be fairly complex. For this reason, there is no single numerical technique that can be used to address all automotive EMC problems. This paper shows how the automotive standard ISO11452-2 can be solved using the hybrid Finite Element Boundary Integral (FEBI) approach. A comparative study indicates that FEBI is faster and requires less computational effort than the Finite Element Method (FEM) for this particular analysis. Recent technology advances on FEBI are also presented showing the great potential of this technique to address automotive EMC problems. © 2013 IEEE.688693Perry, T.S., Geppert, L., Do portable electronics endanger flight? the evidence mounts (1996) IEEE Spectrum, 33, pp. 26-33Devereux, R.W., Archambeault, B., Fuller, G.L., Assessment of analytical codes for use in modeling aircraft onboard EMI threats (1997) AIAA/IEEE 16th Digital Avionics Systems Conference, pp. 17-24. , Irvine, CAStrauss, B., Avionics interference from portable electronic devices: Review of the Aviation Safety Reporting System database (2002) Proceeding of the 21st Digital Avionics Systems Conference, 2, pp. 13E31-13E38Mologni, J., (2008) A Time-Frequency Domain Analysis of Crosstalk Phenomenon on LIN/CAN Based Architectures, , SAE Technical Paper Series, paper 2008-36-0046Hoene, E., Evaluation and prediction of conducted electromagnetic interference generated by high power density inverters (2001) EPE Conference, , Graz, SchweizBroyde, F., Clavelier, E., Designing power-line filter for their worst-case behaviour (1991) Proc. Int. Symposium on EMC, , Zuerich, S.583ff(2005), Road vehicles-Vehicle test methods for electrical disturbances from narrowband radiated electromagnetic energy, ISO Std. 11451-2(2013), http://www.ansys.com/Products/Simulation+Technology/Electromagnetics/ High-Performance+Electronic+Design/ANSYS+HFSS, ANSYS HFSS website. [Online]. AvailableJin, J., (1993) The Finite Element Method in Electromagnetics, , New York. John Wiley & SonsZhao, K., Lee, J.-F., (2009) A Domain Decomposition Method: A Finite Element Preconditioner for Time-Harmonic Maxwell's Equations, , ISBN: 3639185927, VDM VerlagSong, J., Lu, C.C., Chew, W.C., Multilevel fast multipole algorithm for electromagnetic scattering by large complex objects (1997) IEEE Trans. Antennas Propag., 45, pp. 1488-1493. , OctGope, D., Jandhyala, V., Oct-tree based multilevel low-rank decomposition algorithm for rapid 3D parasitic extraction (2004) IEEE J. Technol. Computer Aided Des., 23, pp. 1575-1580. , NovVouvakis, M.N., Zhao, K., Seo, S.M., Lee, J.-F., A domain decomposition approach for non-conformal couplings between finite and boundary elements for unbounded electromagnetic problems in R3 (2007) J. Comput. Phys., 225 (1), pp. 975-994Zhao, K., Rawat, V., Lee, S.-C., Lee, J.-F., A domain decomposition method with non-conformal meshes for finite periodic and semi-periodic structures (2007) IEEE Trans. Antennas Propag., 55 (9), pp. 2559-2570Zhao, K., Rawat, V., Lee, J.-F., A domain decomposition method for electromagnetic radiation and scattering analysis of multi-target problems (2008) IEEE Trans. Antennas Propag., 56 (8), pp. 2211-2221Harrington, R.F., Field computation by moment methods (1993) IEEE Series on Electromagnetic Waves, , New YorkCangellaris, A.C., Lee, R., The bymoment methods for two-dimensional electromagnetic scattering (1990) IEEE Trans. Antennas Propag., 38 (9), pp. 1429-1437Silvestro, J., Zhao, K., Sligar, A., Hybrid finite element-boundary integral technique for efficient simulation of radiation and scattering (2011) Microw. J., 54 (1), p. 74. , JanZhao, K., Vouvakis, M.N., Lee, J.-F., Solving electromagnetic problems using a novel symmetric FEM-BEM approach (2006) IEEE Trans. Mag, 42 (4), pp. 583-587. , AprCendes, Z., Magnetic field computation using Delaunay triangulation and complementary finite element methods (1983) IEEE Trans. Mag., 19Kwon, D.-H., Burkholder, R.J., Pathak, P.H., Efficient method of moments formulation for large PEC scattering problems using asymptotic phasefront extraction (APE) (2001) IEEE Trans. Antennas Propag., 49 (4), pp. 583-59

Perdas de solo e nutrientes num latossolo vermelho-amarelo ácrico típico, com diferentes sistemas de preparo e sob chuva natural Soil and nutrient losses under different tillage systems in a clayey oxisol under natural rainfall

O processo erosivo é a principal causa de degradação dos solos, trazendo, como consequência, prejuízos ao setor agrícola e ao meio ambiente, com reflexos econômicos e também sociais. Este trabalho foi realizado com o objetivo de avaliar as perdas de solo e nutrientes em diferentes sistemas de preparo num Latossolo Vermelho-Amarelo ácrico típico. Foram instaladas cinco parcelas experimentais contendo os seguintes tratamentos: preparo convencional e cultivo morro abaixo (CMA); preparo convencional e plantio em nível (CEN); preparo com uma grade aradora e uma niveladora e plantio em nível (CNiv); preparo com duas gradagens niveladoras, plantio em nível (NA) e cultivo mínimo em nível (CMN). As perdas de solo foram determinadas pelo método direto durante o ciclo da cultura de algodão, de dezembro de 2005 a junho de 2006. A cada coleta foram retiradas amostras de solo para quantificar as perdas dos nutrientes N, P, K e carbono orgânico (C-org) nos sedimentos. A diminuição no revolvimento do solo proporcionou menores perdas de sedimento, nutrientes e C-org, destacando o CMN como o mais eficiente. As perdas de N, P, K e C-org nos sedimentos apresentaram tendências semelhantes às das perdas de solo, e N, P e K variaram conforme as adubações utilizadas. O C-org foi encontrado em maior quantidade no sedimento. A taxa de infiltração básica (TIB) expressou diferença entre os tratamentos na seguinte ordem em valores crescentes: CMA < CEN<img src="/img/revistas/rbcs/v33n3/a21apro.gif" align="absmiddle"> CNiv<img src="/img/revistas/rbcs/v33n3/a21apro.gif" align="absmiddle"> NA < CMN, demonstrando que os sistemas de preparo que minimizam a movimentação do solo e incrementam C-org aumentam a TIB e diminuem o processo erosivo.<br>Erosion is the main cause of soil degradation, and it leads to adverse effects to agriculture and environment, with social and economic implications. The objective of this study was to evaluate soil and nutrient losses in different soil tillage systems in a typic Acric Red-Yellow Latosol (Oxisol). On five plots with the following soil tillage treatments were evaluated: conventional tillage and down-slope tillage (CMA); conventional tillage and contour seeding (CEN); tillage with one passage of heavy disk harrow and one passage of leveling harrow and contour seeding (CNiv); tillage with two passages of leveling harrow and contour seeding (NA) and no tillage and contour seeding (CMN). The soil losses were determined by the direct method during the cotton crop cycle, from December 2005 to June 2006. Along each runoff sampling, soil samples were withdrawn to quantify the losses of N, P, K and organic carbon (C-org) in the sediments. Decreasing soil tillage lessened the losses of sediments, nutrients and organic carbon, indicating that the CMN treatment was the most efficient. The trends for N, P, K and C-org losses in the sediments were similar to the soil losses. N, P and K varied according to the fertilizers used. The constituent with the highest concentration in the sediment was C in organic compounds. The basic infiltration rate differed among the treatments in the following order: CMA < CEN <img src="/img/revistas/rbcs/v33n3/a21apro.gif" align="absmiddle"> CNiv <img src="/img/revistas/rbcs/v33n3/a21apro.gif" align="absmiddle"> NA < CMN, indicating that tillage systems that reduced soil revolving and increased organic C, increased the basic infiltration rate and decreased soil erosion