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A dynamic model of a TCP-session at the management by a length of queue with the use of RED mechanism
No full textAbstract -a mathematical model of TCP-session of data communication at the management by a length of queue with the use of congestion avoidance mechanism -RED (Random Early Detection) -is proposed. This model is expressed by differential equations, which represent the dynamic of information exchange between hosts
STUDIES OF SOME NOVEL METAL COMPLEXES STUDIES OF SOME NOVEL METAL COMPLEXES OF SOME MACRO ORGANIC LIGANDS CONTAINING NITROGEN AND SULPHUR AS POTENTIAL DONOR ATOMS
No full textABSTRACT Some novel complexes of ligands N -(5-Bromo-Napthyl) -2-mercapto propanamide and N-(5-methoxy Napthyl) -2-mercapto propanamide with Cu(II), Ni(II) and Co(II) were prepared. The ligands and their metal complexes were characterized by Physico -chemical spectroscopic techniques. The spectral data suggested the deprotonation of thiol (-SH) group and its coordination to the metal ions in complexes. It was also suggested to involve NH group in coordination to the metal ion through nitrogen atom. Further, spectroscopic studies suggested tetrahedral, octahedral Cu(II) complexes, octahedral Ni(II) complexes and square planar as well as octahedral Co(II) complexes. Keywords: N-(5-Bromo-Naphthyl) -2-mercapto propanamide (L), N-(5-methoxy-Naphthyl) -2-mercapto propanamide (L')
A Performance-Based Design Approach for Rectangular Concrete-Filled Steel Tube (RCFT) Frames under Seismic Loading
No full textFluid Flow Through Triangular and Square Cylinders
No full textCharacteristicsof fluid flowing through triangular and square cylindershas been analyzed experimentally andnumerically by CFDat Reynolds number based on square cylinders diameter, ReD = 14.730;26.040 and 37.192. Ratio of the distance between cylinders to square cylinders diameter (L/D) was variedas0.0;1.0; 2.0; 3.0; 4.0; and 5.0 while ratio of the triangular cylinders diameter to square cylinders diameter (d/D) was constant at 0.5. The results showed that the vortex is damped between the triangular cylinders and the square cylinders as L/D is increased so that the flow tends to attacht the square cylinder. Consequently,the average drag coefficient(CD)decreases and reached minimum L/D=1. Further increase of L/D from 1strengthens the vortex that tends to deflect the flow direction out of the square cylinder so that separation occured earlier in the upstream side of square cylinders.As a result, CD increases. Ingeneral, the insertion of a triangular cylinders in front of a square cylinder decrease dragon square cylinders, by 49%
Online) An Open Access
No full textABSTRACT An assessment of sediment, water and biota samples fromBonny Estuaryin Southern Nigeria was carried outto determine the organochlorine pesticides (OCPs) residue levels in the water body. The analyzed OCPs wereAlachlor, Aldrin, Altrazine, α -BHC, β-BHC, γ-BHC, δ-BHC, Chlorobenzilate, Chlorothalonil, Chloroneb, Dacthal, p,p`-DDD, p`p`-DDE, p,p`-DDT, Dieldrin, Endosulfan, Endosulfan II, Endosulfan sulfate, Endrin, Endrin aldehyde, Etridiazole, α-Chlordane, γ-Chlordane, Heptachlor, Heptachlor epoxide, Methoxychlor, trans-Permethrin, cis-Permethrin, Simazine and trans-Nonachlor. Pesticides in the samples were determined in accordance with USEPA 8080 using Gas chromotographyMass spectrometry. The concentrationsof these OCPs determined were found to be<0.0001µg/kg in all samples of the environmental matrices analyzed (which is below the limit of detection of the instrument). This concentration implies that this river is relatively free of OCP contamination and suitable for plants, animal and human utilization
Spatial-Correlation-Based Antenna Grouping for MIMO Systems
No full textAbstract-We investigate antenna-grouping algorithms, which are hybrids of beamforming and spatial multiplexing. We partition transmit antennas into several groups and use beamforming in a group and spatial multiplexing between groups. With antenna grouping, we can achieve diversity gain through beamforming and spectral efficiency through spatial multiplexing. In this paper, we review existing criteria and present several new criteria in multiple-input-multiple-output (MIMO) antenna-grouping systems where the number of transmit antennas is larger than that of receive antennas. We then propose a novel low-complexity antenna-grouping algorithm, which reduces the computational complexity with little degradation of the bit error rate (BER). Comparing the BER and complexity with existing criteria, we demonstrate the benefits of the proposed algorithm. We also derive the BER lower bound of the proposed algorithm in independent and identically distributed (i.i.d.) channels by using the probability density function of the largest eigenvalue of a Wishart matrix
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No full textAbstract: We have developed a mode transformer comprising two custom refractive optical elements which convert orbital angular momentum states into transverse momentum states. This transformation allows for an efficient measurement of the orbital angular momentum content of an input light beam. We characterise the channel capacity of the system for 50 input modes, giving a maximum value of 3.46 bits per photon. Using an electron multiplying CCD (EMCCD) camera with a laser source attenuated such that on average there is less than one photon present within the system per measurement period, we demonstrate that the elements are efficient for the use in single photon experiments
