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Search Results: 1 - 10 of 614157 matches for " C. M. F.; "
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Localization of Voltage Regulators in Distribution Systems by a Mixed Genetic–Tabu Search Algorithm  [PDF]
M. C. Pimentel Filho, M. F. Medeiros
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B145
Abstract:

The optimal allocation of regulators banks in distribution systems is a merely combinatorial problem in which the best points of installation correspond to the best benefit, considering the admitted objective function, without violating and operating limits. The objective function must be chosen so that its value represents the operation state of the system. As the problem possesses combinatorial nature, its complexity will increase exponentially with the number of possibilities. Systems with large numbers of nodes and / or with the possibility of installing more than one bank require a large number of calculations to find the solution. An additional issue is the fact that the problem does not have a continuous nature, presenting discontinuity points in the objective function, limiting the application of optimization methods based on gradients. Based on the nature of the problem two optimization methods were used to solve the problem: Genetic Algorithm (GA) and modified Tabu Search (TS). The GA function will scour the search space and find regions with local minima that are candidates to be the solution. On the other hand the TS provides local search in the regions defined by GA so that the overall optimum is achieved.

Sex Hormones Secretion Pattern in Pregnant Sickle Cell Subjects in Niger Delta Region, South of Nigeria  [PDF]
F. C. Ezeiruaku, E. M. Eze, C. U. Okeke
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2018, DOI: 10.4236/ojemd.2018.87015
Abstract: Sickle cell anemia (SCA) patients are reported with infertility and low rate of pregnancies. This is associated with wide range of reproductive issues that are still relevant because of the complications and problems of the disease that still persist till date. This study was carried out to establish the secretion pattern of the sex hormones (Progesterone and Estradiol) in the three trimesters of pregnant sickle cell disease subjects in the Niger Delta Region, south of Nigeria. The study included twenty (20) pregnant sickle cell anemia subjects with average age of 27.4 years and twenty (20) apparently healthy (Hemoglobin AA) subjects with average age of 28.2 years. Their samples collection started when they registered for antenatal care at the clinics within the first trimester of pregnancy. The Enzyme Linked Immunosorbent assay (ELISA) method was used in the measurement of the hormones in the plasma of the subjects. The result showed a statistical significant reduction (P < 0.05) in the values of the hormones in the three trimesters obtained for the sickle cell disease (SCD) subjects when compared with apparently healthy subjects with the same age range. Statistical analysis showed a strong positive correlation ((r = 0.8151 for Estradiol and r = 0.8793) for Progesterone) between the secretion of the sex hormones, in the sickle cell subjects and the control. The result is attributed to the sickle cell gene abnormality and the treatment of SCA that affects the endocrine system by inhibiting the production of gonadotropins from the pituitary gland. The SCD itself does not directly damage the reproductive system; however it can affect other systems which will eventually cause harm to the reproductive system. The study concluded that the sickle cell anemia patients require the administration of the hormone drugs during pregnancy to prevent to a certain extent, complications arising from hormonal imbalance.
Water Deficit Stress Effects on Corn (Zea mays, L.) Root:Shoot Ratio  [PDF]
J. G. Benjamin, D. C. Nielsen, M. F. Vigil, M. M. Mikha, F. Calderon
Open Journal of Soil Science (OJSS) , 2014, DOI: 10.4236/ojss.2014.44018
Abstract:

A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.

Left-Ideals, Dirac Fermions and SU(2)-Flavour
F. M. C. Witte
Physics , 2006,
Abstract: In this paper I reconsider the use of the left ideals of the even-grade subalgebra of spacetime algebra to describe fermionic excitations. When interpreted as rotors the general elements of an even-grade left-ideal describe massless particles in chiral flavour doublets. To study the application of these ideas to the standard Dirac formalism I construct a $2 \times 2$-matrix representation with bivector insertions for the Dirac algebra. This algebra has four ideals, and this approach clarifies how the identification of Dirac $\g_{\mu}$-matrices with orthonormal basisvectors ${\bf e}_{\nu}$ annihilates half of the ideals. For one possible choice of this mapping the remaining ideals the chiral left- and righthanded components of the fermion coincide with the even- and odd elements of spacetime algebra.
Free particle states from Geometry
F. M. C. Witte
Physics , 2004,
Abstract: In this short paper I discuss how conformal geometric algebra models for euclidean and minkowski targetspaces determine the allowed quantum mechanical statespaces for free particles. I explicitly treat 2-dimensional euclidean space and (1+1)-dimensional spacetime.
Lightlike infinity in GCA models of Spacetime
F. M. C. Witte
Physics , 2004, DOI: 10.1088/0305-4470/37/42/009
Abstract: This paper discusses a 7 dimensional conformal geometric algebra model for spacetime based on the notion that spacelike and timelike infinities are distinct. I show how naturally of the dimensions represents the lightlike infinity and appears redundant in computations, yet usefull in interpretation
Spindensities in Pseudo-classical kinetic theory
F. M. C. Witte
Physics , 1995,
Abstract: In this paper the classical limit of relativistic transport theories for spin 1/2 fermions is examined through a comparison with the classical kinetic theory derived from N=1 supersymmetric classical mechanics. The conclusion is that in the classical limit spindensities, i.e. the axial-vector contribution to the relativistic Wigner-function, vanishes and dipole-densities, i.e. the spin-tensor contributions to the relativistic Wigner function, may survive.
Symmetry Breaking and Collisions with $σ$-Mesons
F. M. C. Witte
Physics , 1996,
Abstract: In this brief report we adress spontaneous symmetry breaking in a finite-temperature scalar meson plasma. We calculate the in-medium averaged thermal $\sigma-\sigma$ scattering crossection and the related shear viscosity $\eta(T)$ and mean-free-path $L(T)$. Our results suggest that slightly below the critical temperature there is a 30 percent peak in the crossection leading to equivalent dips in $\eta(T)$ and $L(T)$. We discuss the relevance of this observation.
Quantum 2-player gambling and correlated pay-off
F. M. C. Witte
Physics , 2002,
Abstract: I give an analysis of the simplest non-commutative quantum game, which is a gambling game much like Heads or Tails. The quantum gamespace displays strategies which are not interpretable through direct-product strategies of the two players. Yet the pay-off allows for correlations if states corresponding to a different number of rounds played are superposed.
On Pay-off induced Quantum Games
F. M. C. Witte
Physics , 2002,
Abstract: In recent years methods have been proposed to extend classical game theory into the quantum domain. This paper explores further extensions of these ideas that may have a substantial potential for further research. Upon reformulating quantum game theory as a theory of classical games played by "quantum players" I take a constructive approach. The roles of the players and the arbiter are investigated for clues on the nature of the quantum game space. Upon examination of the role of the arbiter, a possible non-commutative nature of pay-off operators can be deduced. I investigate a sub-class of games in which the pay-off operators satisfy non-trivial commutation relations. Non-abelian pay-off operators can be used to generate whole families of quantum games.
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