A Chip-Level BSOR-based linear GSIC multiuser Detector for Long-Code CDMA Systems

In this work, we introduce a chip-level linear group-wise successive interference cancellation (GSIC) multi-user structure that is asymptotically equivalent to block successive over-relaxation (BSOR) iteration, which is known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed. The main advantage of the proposed scheme is that it uses directly the spreading codes instead of the cross-correlation matrix and thus doesn’t require the calculation of the cross-correlation matrix (requires 2NK2 floating point operations (flops), where N is the processing gain and K is the number of users) which reduces significantly the overall computational complexity. Thus it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We study the convergence behavior of the proposed scheme using two approaches and prove that it converges to the decorrelator detector if the over-relaxation factor is in the interval ]0, 2[. Simulation results are in excellent agreement with theory

A Chip-Level BSOR-based linear GSIC multiuser Detector for Long-Code CDMA Systems

In this work, we introduce a chip-level linear group-wise successive interference cancellation (GSIC) multi-user structure that is asymptotically equivalent to block successive over-relaxation (BSOR) iteration, which is known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed. The main advantage of the proposed scheme is that it uses directly the spreading codes instead of the cross-correlation matrix and thus doesn’t require the calculation of the cross-correlation matrix (requires 2NK2 floating point operations (flops), where N is the processing gain and K is the number of users) which reduces significantly the overall computational complexity. Thus it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We study the convergence behavior of the proposed scheme using two approaches and prove that it converges to the decorrelator detector if the over-relaxation factor is in the interval ]0, 2[. Simulation results are in excellent agreement with theory

A Chip-Level BSOR-based linear GSIC multiuser Detector for Long-Code CDMA Systems

In this work, we introduce a chip-level linear group-wise successive interference cancellation (GSIC) multi-user structure that is asymptotically equivalent to block successive over-relaxation (BSOR) iteration, which is known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed. The main advantage of the proposed scheme is that it uses directly the spreading codes instead of the cross-correlation matrix and thus doesn’t require the calculation of the cross-correlation matrix (requires 2NK2 floating point operations (flops), where N is the processing gain and K is the number of users) which reduces significantly the overall computational complexity. Thus it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We study the convergence behavior of the proposed scheme using two approaches and prove that it converges to the decorrelator detector if the over-relaxation factor is in the interval ]0, 2[. Simulation results are in excellent agreement with theory

A New Linear Group-Wise SIC multiuser Detector

In this work, we introduce a new linear groupwise SIC multi-user detector that can converge to either the decorrelator or the least minimum mean-square error (LMMSE) detector. We study the convergence behavior of the proposed scheme and show that the latter is equivalent to the block Gauss- Seidel iterative method if the group-detection scheme used is the decorrelator detector. Moreover, we prove that the latter is convergent if the group-detection matrix is positive definite. Our simulation results are in excellent agreement with the proposed theory

A New Linear Group-Wise SIC multiuser Detector

In this work, we introduce a new linear groupwise SIC multi-user detector that can converge to either the decorrelator or the least minimum mean-square error (LMMSE) detector. We study the convergence behavior of the proposed scheme and show that the latter is equivalent to the block Gauss- Seidel iterative method if the group-detection scheme used is the decorrelator detector. Moreover, we prove that the latter is convergent if the group-detection matrix is positive definite. Our simulation results are in excellent agreement with the proposed theory

A New Linear Group-Wise SIC multiuser Detector

In this work, we introduce a new linear groupwise SIC multi-user detector that can converge to either the decorrelator or the least minimum mean-square error (LMMSE) detector. We study the convergence behavior of the proposed scheme and show that the latter is equivalent to the block Gauss- Seidel iterative method if the group-detection scheme used is the decorrelator detector. Moreover, we prove that the latter is convergent if the group-detection matrix is positive definite. Our simulation results are in excellent agreement with the proposed theory

Removal of phosphate from aqueous solution with modified sawdust

In the present study, chemically modified Aleppo pine (Pinus halepensis Miller) sawdust was used for removal of phosphate from water. The sawdust preparation process included size fractionation, extraction for surface activation, acid prehydrolysis, and treatment with urea. Sorption of phosphate ions onto the sawdust modified was studied using the batch technique. The effect of different parameters such as contact time, adsorbate concentration, and temperature was investigated. The adsorption kinetics data were best described by the pseudo-second-order rate equation, and equilibrium was achieved after 40 min. The Langmuir and Freundlich equations for describing adsorption equilibrium were applied to data. The constants and correlation coefficients of these isotherm models were calculated and compared. The adsorption isotherms obey the Freundlich equation. The thermodynamic parameters like free energy, enthalpy and entropy changes for the adsorption of phosphate ions have been evaluated and it has been found that the reaction was spontaneous and endothermic in nature. The low value of activated energy of adsorption, 3.088 Kj/mol, indicates that the phosphate ions are easily adsorbed on the sawdust. Results suggest that the prepared chemically modified Aleppo pine sawdust has potential in remediation of contaminated waters by phosphat

Removal of phosphorus from aqueous solutions using chemically modified sawdust of Aleppo pine (Pinus halepensis Miller) : kinetics and isotherm studies

In the present study, chemically modified Aleppo pine (Pinus halepensis Miller) sawdust was used for the removal of phosphate from water. Biosorbent preparation process included size fractionation, extraction for surface activation, acid prehydrolysis, and treatment with urea. Sorption of phosphate ions onto biosorbent was studied using the batch technique. The effect of different parameters such as contact time, adsorbate concentration, and temperature was investigated. The adsorption kinetics data were best described by the pseudo-second-order rate equation, and equilibrium was achieved after 40 and 80 min for modified and unmodified sawdust, respectively. The Langmuir and Freundlich equations for describing adsorption equilibrium were applied to data. The constants and correlation coefficients of these isotherm models were calculated and compared. The adsorption isotherms obey the Freundlich equation. The thermodynamic parameters like free energy, enthalpy, and entropy changes for the adsorption of phosphate ions have been evaluated, and it has been found that the reaction was spontaneous and endothermic in nature. The low value of activated energy of adsorption, 3.088–3.540 kJ mol-1, indicates that the phosphate ions are easily adsorbed on the sawdust. Results suggest that the prepared chemically modified Aleppo pine sawdust has potential in remediation of contaminated waters by phosphat

Removal of phosphate from aqueous solution with modified sawdust

In the present study, chemically modified Aleppo pine (Pinus halepensis Miller) sawdust was used for removal of phosphate from water. The sawdust preparation process included size fractionation, extraction for surface activation, acid prehydrolysis, and treatment with urea. Sorption of phosphate ions onto the sawdust modified was studied using the batch technique. The effect of different parameters such as contact time, adsorbate concentration, and temperature was investigated. The adsorption kinetics data were best described by the pseudo-second-order rate equation, and equilibrium was achieved after 40 min. The Langmuir and Freundlich equations for describing adsorption equilibrium were applied to data. The constants and correlation coefficients of these isotherm models were calculated and compared. The adsorption isotherms obey the Freundlich equation. The thermodynamic parameters like free energy, enthalpy and entropy changes for the adsorption of phosphate ions have been evaluated and it has been found that the reaction was spontaneous and endothermic in nature. The low value of activated energy of adsorption, 3.088 Kj/mol, indicates that the phosphate ions are easily adsorbed on the sawdust. Results suggest that the prepared chemically modified Aleppo pine sawdust has potential in remediation of contaminated waters by phosphat

Stiffness and energy dissipation of Oval Leaf Spring mounts under unidirectional line loading

The Oval Leaf Springs (OLS), a class of passive isolation devices, have been successfully used as anti-shock and anti-vibration mounts to protect equipment and machinery. Available literature is insufficient to understand the behavior of OLS mounts. To estimate the spring stiffness, we conducted theoretical and finite element analyses (FEA) on a large number of springs having different geometrical and mechanical properties. Based on the principle of minimum potential energy, this paper presents theoretical expressions, which describe the linear static stiffness of OLS mounts subjected to line loading in the vertical (compression) and lateral (bending–shear) in-plane directions. Comparison studies showed a good agreement between numerical and analytical models. We observed a negligible effect of transverse shearing on the spring stiffness. In addition, it was demonstrated that the stiffness is more sensitive to the radius compared to the other geometric properties of the spring. Nonlinear FEA considering the hyper-viscoelastic behavior of the damping compound showed that the OLS mounts have higher energy dissipation capabilities in the lateral direction, which increase at low frequency and large amplitude loadings