Signal behaviour in an indoor environment: femtocell over macrocell

Abstract: In this paper, we consider femtocells over macrocell for improved signal, good quality of voice calling, data and Internet use in the indoor environment, where there is poor reception of signals. Mobile networks have become most frequent means of communication in well-developed areas and some other places in the world for communication and business purposes. Therefore, the deployment of femtocells has drawn the attention of mobile industry experts, researcher and other standardization organizations over macrocells. The interesting part of the femtocell is that it improves coverage, enhances the data rate at the indoor environment and more so used for security purpose. We focus on benefits of deployment of femtocells and how femtocells can optimize the total capacity of mobile network where there is poor reception. In this paper, we simulate the signal behavior of femtocell over macrocell in an indoor setting, to illustrate that femtocell improved signal and voice calling in an indoor environment

Influence of pulverized palm kernel and egg shell additives on the hardness, coefficient of friction and microstructure of grey cast iron material for advance applications

Previous studies showed the effects of organic carbon on the mechanical properties of alloys. However, the mechanisms of graphite films formation have not been given due attention. In the present study, diffusion of carbon content via heat treatment process to produce graphite films is presented using microstructure. Consequently, the graphite films formed a protective layer on the heat treated metals which cause hardness increase and in turn improved the wear resistance of the heat treated material due to reduced coefficient of friction. The excellent tribological properties of carburized grey cast iron showed the potentials of palm kernel and egg shell for advance material modification

Network congestion management using Call Admission Control

Abstract: Call Admission Control schemes have been used extensively in improving mobile network quality. Signal quality degradation, interference and network congestion has been a real issue for Global System for Mobile Communication (GSM) as the number of mobile users increased rapidly. It has been an issue in providing a decent Quality of Service (QoS) to the network users especially during the period of high network traffic. It is essential to maintain a certain level of quality in handling mobile network congestion. Fortunately, Call Admission Control is a strategy that can provide credible QoS by limiting the number of connections into the cellular network thereby reducing network congestions, dropping of calls, interference and other QoS problems. In this paper, we discuss issues around mobile network congestion, overview of congestion management schemes, attributes and benefits of Call Admission Control (CAC). We also highlight different handoff schemes. We simulated a typical CAC scheme comparing the new call blocking probability and handoff call probability

Comparative effects of organic and inorganic bio-fillers on the hydrophobicity of polylactic acid

The use of Polylactic acid (PLA) has been limited in the biomedical field because of its slow degradation profile which is traceable to its degree of hydrophobicity. In this work, 16.67 wt. % of chitosan (Ch), chitin (Ct) and titanium (Ti-6Al-2Sn-2Mo-2Cr-0.25Si) (Ti) powders weremelt blended with PLA and the resulting composites examined using Fourier Transform Infrared Spectroscopy (FTIR). Chitosan was found to reduce the hydrophobic peak due to δs(CH3) in PLA by 13.92%, chitin by 10.65% and titanium by 8.04%. Summarily, the organic biofillers produced more hydrophilic PLA composites than the inorganic filler. The percentage reduction in hydrophobicity renders the developed composites more suitable for orthopaedic applications

The Strength characteristics of Chitosan‐ and Titanium‐ Poly (L‐lactic) Acid Based Composites

The problem of bone fracture and the need to avoid revision surgery in osteosynthesis are the critical reasons for the gradual shift from the use of metallic fixations to the polymeric scaffold in the orthopaedic applications. However, the mechanical properties of polymers that have become a substitute for metals need to be improved upon. An attempt was made to improve the mechanical properties of poly(L‐lactic) acid (PLLA), a biopolymer, by loading it with 1.04, 2.08, 4.17, 8.33 and 16.67 wt.% of chitosan (an organic filler) and Ti‐6Al‐2Sn‐2Mo‐2Cr‐0.25Si (an inorganic particle). Melt blend technique was the processing technique. Hardness, compressive modulus and fracture toughness of virgin PLLA improved significantly while the resulting composites were found to be less ductile than unreinforced PLLA. Titanium reinforced PLLA displayed superior mechanical properties over the neat and chitin reinforced PLLA. Compressive modulus values of the developed composites were much lower than the modulus of cortical bone, they were, however, mechanically compatible with the properties of cancellous bone. Optical microscopy images also show the formation of pores which are a catalyst for cell proliferation and cell differentiation

Parametric Effects of Fused Deposition Modelling on the Mechanical Properties of Polylactide Composites: A Review

Polymers are generally inferior in mechanical properties to metals which are the current orthopaedic material for osseointegration in many parts of the world today. This assertion also applies to poly(lactic acid) (PLA), a polyester that has been recently found applicable in tissue remodelling. To improve on its mechanical properties, several processing techniques, inclusive of fused deposition modelling (FDM) also branded as fused filament fabrication (FFF), have been used. FDM has been endeared to many researchers because a range of parameters can be combined to bring about widely different mechanical properties. Although the influence of FDM parameters on the mechanical properties of PLA is clear, the tensile, compressive and flexural strengths obtained so far are inferior to human cortical bone. The need to improve on this production technique for improved mechanical properties is apparent in all the works examined in this revie

Analytic and Numerical Solutions of Time-Fractional Linear Schrödinger Equation

Fractional Schrödinger equation is a basic equation in fractional quantum mechanics. In this paper, we consider both analytic and numerical solutions of time-fractional linear Schrödinger Equations. This is done via a proposed semi-analytical method upon the modification of the classical Differential Transformation Method (DTM). Some illustrative examples are used; the results obtained converge faster to their exact forms. This shows that this modified version is very efficient, and reliable; as less computational work is involved, even without given up accuracy. Therefore, it is strongly recommended for both linear and nonlinear time-fractional partial differential equations (PDEs) with applications in other areas of applied sciences, management, and finance

On a Modified Iterative Method for the Solutions of Advection Model

Variational Iterative Method (VIM) has been reported in literature as a powerful semi-analytical method for solving linear and nonlinear differential equations; however, it has also been shown to have some weaknesses such as calculation of unneeded terms, and time-consumption regarding repeated calculations for series solution. In this work, a modified VIM is applied for approximate-analytical solution of homogeneous advection model. The result attest to the robustness and efficiency of the proposed method (MVIM)

A review of femtocell

The popularity of wireless networks has attracted the attention of researchers to improve the network system and this motivated the operators to find a new technology called femtocells with the aim of meeting the increased coverage and data demand in the indoor environment. The application of femtocells in both indoors and office environment has provided good quality service and high performance network gains. However, femtocells face challenges of interference management which deteriorate the capacity and quality of network. But to cope with these challenges, many researchers have come up with solutions to solve the problems, some of which include interference cancellation and interference avoidance