Active Queue Management for Fair Resource Allocation in Wireless Networks

This paper investigates the interaction between end-to-end flow control and medium access control (MAC)-layer scheduling on wireless links. We consider a wireless network with multiple users receiving information from a common access point; each user suffers fading and a scheduler allocates the channel based on channel quality but is subject to fairness and latency considerations. We show that the fairness property of the scheduler is compromised by the transport-layer flow control of transmission control protocol (TCP) New Reno. We provide a receiver-side control algorithm, CLAMP, that remedies this situation. CLAMP works at a receiver to control a TCP sender by setting the TCP receiver's advertised window limit, and this allows the scheduler to allocate bandwidth fairly between the users.     

Modelling and simulation of single- and triple-junction solar cells using MATLAB/SIMULINK

The main objective of this paper is to determine the single- and triple-junction solar cells’ I–V and P–V curves, define maximum voltage, current, and power. The paper demonstrates and analyses different environmental conditions that affect the solar cells, such as temperature and irradiance. The performance of single- and triple-junction solar cells is evaluated by analysing the fill factor. In this work, the analysis of single- and triple-junction solar cells is carried out through software simulation. Different conditions demonstrated to observe the results of this variation in both single- and triple-junction cells, such as observing the solar cell behaviour under variation of temperature between 15°C (288.315?K) and 45°C (318.15?K) for the single-junction cell and between 268.15?K (?5°C) and 348.15?K (75°C) for the triple-junction cell to observe the effect of temperature on open circuit voltage, the variation of different levels of irradiance to observe its effect on open circuit voltage and current density on both cell types, and cell performance evaluation using the fill factor concept. Practical results used in this paper are obtained from Clyde Space’s laboratories. Tests of Clyde Space were done using halide lamps to simulate the irradiation conditions with irradiance of half sun which is equivalent to 0.05?W?cm^?2. The operation was done under temperature of 40°C which is equivalent to 313.15?K.     

Metabolite profiling and inhibitory properties of leaf extracts of Ficus benjamina towards α-glucosidase and α-amylase

The use of antioxidant-rich medicinal plants having the potential to reduce oxidative stress and postprandial hyperglycemic pressure is one of the most promising option for the management of diabetes. This study presents information on metabolite profiling and in vitro anti-diabetic effects of leaf extracts of Ficus benjamina. The DPPH (2, 2-diphenyl-1-picrylhydrazyl radicals) assay was performed to determine the in vitro antioxidant potential of the plant extracts. The anti-diabetic effects were investigated by evaluating inhibitory properties of F. benjamina leaf extracts towards carbohydrate hydrolyzing enzymes, i.e., α-glucosidase and α-amylase, whereas ¹H NMR and UHPLC-QTOF-MS/MS analytical methods were employed for metabolite profiling of F. benjamina leaf extracts. Among 40, 60, 80, and 100% ethanolic leaf extracts of F. benjamina, 80% ethanolic extract exhibited the highest antioxidant activity based upon its DPPH radical scavenging ability (IC₅₀ value: 63.71 ± 2.66 µg/mL). The 80% ethanolic leaf extract of F. benjamina also proved to be the most efficient α-glucosidase and α-amylase inhibitor with IC₅₀ values of 9.65 ± 1.04 µg/mL and 13.08 ± 1.06 µg/mL, respectively; these values were even better than acarbose with α-glucosidase inhibition activity (IC₅₀ = 116.01 ± 3.83 µg/mL) and α-amylase inhibition activity (IC₅₀ = 152.66 ± 7.32 µg/mL). Moreover, a total of 31 metabolites were identified in F. benjamina leaf extract, which may have the potential to contribute to its antioxidant and inhibitory properties against carbohydrate hydrolyzing enzymes. The findings of this study depict F. benjamina leaf extracts as a promising α-glucosidase and α-amylase inhibitor, and therefore, can be utilized for the development of anti-diabetic functional diets/nutra-pharmaceuticals.     

Application of Doubly Fed Induction Motor in Power System State Measurements

In a large interconnected power system, any strategy for the control of transient modes after a major disturbance requires a fast and reasonably accurate measurement of power angle and speed or frequency deviations. These data are given to the controlling device for performing the corrective actions.     

Nuclear track formation and skewness of particle trajectories in the target: A new perspective

It is discussed why track detectors such as CR-39 and CN-85, which are only composed of light elements, are highly sensitive and efficient compared with detectors such as glass and mica, which are partly or fully composed of heavier elements. Weak scattering of incident particles by light target atoms does not significantly deviate incident particles from their straight trajectories while the target atoms recoil considerably, damaging the detector. Heavier atoms scatter incident particles through wide angles, significantly deviating them from their straight paths while the target atoms recoil weakly, producing less damage. Simulations are presented to demonstrate these concepts about nuclear track formation.     

Selective microwave absorption in Nd3+ substituted barium ferrite composites

Microwave(MW) frequency based wireless communications and electronic devices became prospective due to several ramifications.To meet this need,a series of neodymium ions(Nd3+) substituted barium ferrite composites with composition(20)BaO:(80-x)Fe_2 O_3:(x)Nd_2 O_3(0≤x≤3 mol%) was prepared at1100℃using solid-state reaction method.We evaluated the effect of various Nd3+ions contents on the surface morphology,structure,and magnetic properties of the as-synthesized barium ferrite composites.Meanwhile,microwave reflection loss,complex permittivity and permeability were determined using the transmission/reflection line method in the X-band(8—12 GHz).SEM image of the composites shows that the surface morphology consists of rough and porous microstructures.XRD patterns of the un-doped composites reveal the existence of BaFe_(12)O_(19)(hexagonal) and Fe_(21.333)O_(32)(tetragonal) crystalline phases.Furthermore,a new hexagonal crystalline phase of Ba_6 Nd_2 Fe_4 O_(15) with the crystallite sizes between 15 and 67 nm is observed due to Nd3+ions substitution in the composite.The saturation magnetization of the composite containing 2 mol% of Nd3+does not exhibit any significant alteration compared to the one devoid of Nd3+.The complex relative permitivity and permeability of the achieved composites enriched in Ba_6 Nd_2 Fe_4 O_(15) and BaFe_2 O_4 phases disclose significant MW frequency dependence.The composites also display selective MW absorption in the X-band which could be useful for diverse applications.     

Aluminium and cerium co-doped ZnO nanoparticles:Facile and inexpensive synthesis and visible light photocatalytic performances

Facile combustion route synthesized Al and Ce co-doped ZnO nanoparticles photocatalysts were characterized using XRD,SEM,BET,EDS,UV-visible DRS,PL,photocurrent and EIS techniques.XRD and SEM analyses identify that crystallite and particle size is reduced from 13.26 to 11.88 nm with introduction of Al and Ce into ZnO which assists inhibiting the recombination of photo generated charge carriers.UVvisible DRS spectra indicate that optical assimilation of ZnO is significantly increased to visible region(-406 nm)and band gap reduces from 3.18 to 3.06 eV with introduction of Al and Ce co-dopants.Electrochemical impedance spectroscopy analysis under visible light illumination confirms the enhancement in visible light activity of Al and Ce co-doped ZnO nanoparticles as photocatalysts.The enhanced activity of Al and Ce co-doped ZnO photocatalyst can be ascribed to enhanced light assimilation,high surface area and efficient charge transfer process.Our results reveal that by incorporating precise amount of Al(~2%)and Ce(~2%)into ZnO,a highly efficient catalyst can be synthesized that have degraded almost 95%methyl orange(MO)dye in just 45 min.Further,the influence of various operational parameters such as solution pH,catalyst dose,dye concentration,airflow rate and light intensity on photodecomposition of MO was evaluated.Furthe rmore,a possible mechanism for Al and Ce modified ZnO was proposed and designed photocatalysts demonstrates good stability in aqueous medium.     

Synthesis and investigations of structural,magnetic and dielectric properties of Cr-substituted W-type Hexaferrites for high frequency applications

Journal of Electroceramics - In current study, Cr-substituted W-type hexaferrites with chemical formula (BaNi2CrxFe16-xO27 for x?=?0.0, 0.1, 0.2, 0.3 and 0.4) have been investigated in...     

Sol–gel synthesis of Cu0.9Zn0.05M0.05O (M = Cr,Co, Cd) nanocrystals for removal of pollutant dyes and bacterial inactivation

Journal of Materials Science: Materials in Electronics - In this work, we focus on the synthesis of Cu0.95Zn0.05O and Cu0.9Zn0.05M0.05O (M?=?Cr, Co, Cd) nanocrystals by employing...