Assessment of Capacity and Impacts of 8.5 MW Gas Fired Power Plant on Soil and Water Quality in Lekki, Lagos State Nigeria

The aim of this study is to evaluate the potential impacts of 8.5 MW thermal power plant on soil and water quality within its location, Lekki area, Lagos State. The study area was geo-referenced using the existing map and Geographical Positioning System. Auger was used to sample soil at three different locations within the power plant. The soil samples were prepared and analyzed for the following parameters using standard analytical methods. The parameters include soil texture, Exchangeable cations and anions (H+, Na+, Ca2+, Mg2+, Cl- and SO42-) Nutrients compounds (NO3-, Total Nitrogen (TN), Organic Carbon (OC) and heavy metals (Fe, Cd, As, and Mn). Surface and groundwater samples were collected within the power plant in triplicate and analyzed for true colour, turbidity, conductivity, salinity, THC and Coliform. Dissolved Oxygen (DO), BOD5, Total Organic Carbon (TOC), Organic Matter (OM) and heavy metals (As, Ag, Fe and Mn) of water samples were also analyzed. The soil from the study area is loamy-sand in texture. The average As, Ag, Fe and Mn in surface and groundwater samples were 0.055, 0.025, 3.150, 0.735 and 0.12, 0.080, 6.440 and 0.180 mg/L, respectively. The gas-fired power plant has contaminated the soil and water within its premises with petroleum and heavy metals. The engine stack should be modified to minimize the pollution effects of the power plant on the environment.

Simulation and analysis of a Single Mode Indium Gallium Arsenide Phosphide Vertical Cavity Surface Emitting Laser for Optical Communication

This present work is about simulating and analysing a Vertical Cavity Surface Emitting Laser (VCSEL) structure used in optical fibre communication systems. In this paper a VCSEL structure made of seven Quantum Wells of Indium Gallium Arsenide Phosphide (InGaAsP) emitting at 1550 nm is simulated. The device is analysed looking at the following characteristics: Direct current current and voltage (IV) characteristics, light power against electrical bias, optical gain against electrical bias, light distribution over the structure, output power and threshold current. Specification of material characteristics, ordinary physical models settings, initial VCSEL biasing, mesh declarations, declaration of laser physical models, their optical and electrical parameters were defined using Atlas syntax. Mirror ratings and quantum wells are the two main parameters that were studied and analysed to come up with structure trends. By determining important device parameters such as proper selection of the emission wavelength and choice of material; a VCSEL with an output power of 9.5 mW was simulated and compared with other structures.

An Electromechanical In Situ Viscosity Measurement Technique for Shear Thickening Fluids

This paper presents the feasibility of developing an electromechanical in-situ viscosity measurement technique by analyzing the detectability of small variations in the viscosity of different shear thickening fluids and their different compositions. Shear thickening fluid (STF) is a kind of non-Newtonian fluid showing an increasing viscosity profile under loading. STF is utilized in several applications to take advantage of its tunable rheology. However, process control in different STF applications requires rheological measurements, which cause a costly investment and long-lasting labor. Therefore, one of the most commonly used in-situ structural health monitoring techniques, electromechanical impedance (EMI), was used in this study. In order to actuate the medium electromechanically, a piezoelectric wafer active sensor (PWAS) was used. The variations in the spectral response of PWAS resonator that can be submerged into shear thickening fluid are analyzed by the root mean square deviation, mean absolute percentage deviation and correlation coefficient deviation. According to the results, EMI metrics provide good correlations with the rheological parameters of STF and thereby enabling quick and low-cost rheological control for STF applications such as vibration dampers or stiffness control systems.

The Role of Smart Technologies to Improve the Utilization of Wood Uses in Engineering Applications: A Review

Nowadays, smart technology plays an important role in engineering applications to improve the quality of life. Thus, the development of natural materials and the use of nanotechnology, will give wood new properties to maximize its benefit. It is clear that there is a great challenge to prove the strength and durability of wood acquiring new features to reach innovative use that can influence the current path in many engineering applications. Therefore, this paper summarizes a review of the possibility of using nano- and smart-technologies to make the most of the natural and acquired potential for adding new features and physical properties of wood to improve its efficiency in architectural and mechanical applications. Moreover, experiments have shown that the use of certain types of wood in many applications such as the manufacture of 3D vehicle simulation models to study dynamic behaviors as well as in the manufacture of mechanical measurement systems to improve accuracy. In conclusion, new directions under development in this field are proposed to provide solutions to important issues in the future of measurement and quality control systems that need scientific treatment.--

Influence of the Curvature Correction on Turbulence Models for the Prediction of the Aerodynamic Coefficients of the S809 Airfoil

Using the appropriate procedure, Computational Fluid Dynamics allows predicting many things in several fields, and especially in the field of renewable energies, which has become a promising research axis. The present study aims at highlighting the influence of the curvature correction on turbulence models for the prediction of the aerodynamic coefficients of the S809 airfoil using the Computational Fluid Dynamics code ANSYS Fluent 17.2. Three turbulence models are used: Spalart-Allmaras, Shear Stress Transport k-ω and Transition SST. Experimental results of the 1.8 m × 1.25 m low-turbulence wind tunnel at the Delft University of Technology are used in this work for comparison with the numerical results for a Reynolds number of 106. The results show that the use of the curvature correction improves the prediction of the aerodynamic coefficients for all the turbulence models used. A comparison of the three models is also made using curvature correction since it gave better results. The Transition SST model is the one that gives the best results for the lift coefficient, followed by the Shear Stress Transport kω model, and finally the Spalart-Allmaras model. For the drag coefficient, Transition SST model is the best, followed by the Spalart-Allmaras model, and finally the Shear Stress Transport kω model.

Experimental Investigations on Salt Gradient Solar Pond with Additional Non-Convective Zone for Improved Thermal Performance and Stability

Salt gradient solar ponds are to be designed for thermal efficiency and salinity profile stability. As the salt flux moves upward in the pond, the gradient gets destabilized. This is counteracted by intrusion of salt at different levels as and when required. The density of salt is highest at the bottom and minimum at the top. Hence the destabilization effect is more at top that is at the interface of upper convective zone and non-convective zone (NCZ). In order to keep the interface stable, it is desirable to provide a higher slope of salt gradient near it. However, throughout the non-convective zone, it is not feasible to provide higher slope due to solubility limitations. Hence Husain et al (2012) to divide the NCZ into two parts. The top few centimeters may be given a higher slope and the rest of the zone may be given mild slope as usual. Husain et al (2012) have given analysis for the same and found it to be feasible. However, the experimental feasibility of the same needs to be verified. The present work has done an attempt for the same. In this study, an insulated solar pond with a surface area of 1.40 m2and a depth of 1.14 m is built at the SSBT’s College of Engineering and Technology, Jalgaon in the Maharashtra State (India). The three salty water zones (upper convective, non-convective and heat storage) were formed by filling the pond with salty water of various densities. 6 Thermocouples (type Pt100A) (C+0.2%) were used to measure the temperature profile within the pond. A maximum temperature of 47°C was recorded in the heat storage zone in time span considered for study. The results obtained from experimentation is verified with the concept suggested by Hussain et al (2012) it has been found that they are in a good agreement. The influence of varying the thicknesses of the zones present in a salinity gradient solar pond on the temperatures of the upper convective zone (UCZ) and the lower convective zone (LCZ) is investigated. Also, it is found that by adding the additional non convective zone of 50 mm thickness above the UCZ the heat collection capacity of the LCZ is increased noticeably. The study finds that thickness variation of the zones within the pond is a practical feasibility. The system worked for the entire experimental duration effectively without failure.

Parametric Investigation of Photochemical Machining of SS- 430 for Manufacturing of Micromesh

Photochemical machining (PCM) is an emerging method for machining of very thin and difficult-to-cut material with complex geometrical profile. PCM is one of recommended method for machining of aerospace components, biomedical appliances, electronics part and decorative items. High corrosion resistance, better life, good appearance and strength recommend SS-430 as suitable material for various applications. In the current investigation, the parametric investigations of process parameters in photochemical machining for concentration and temperature of etchant, time of etching is done through ANOVA analysis. Grey Relational Analysis is performed to estimate the optimum machining parameters during PCM of SS-430. Formulation of mathematical model is done for prediction of results. Taguchi (L27) experimental array is used for Design of Experiments (DoE). The significance process parameters are estimated to govern the process with F-Values. Confirmatory test is conducted to observe the improvement in the responses. ANN predictive model is built up for investigation of error between predictive and experimental values. The obtained optimum set is used for manufacturing of micromesh typically used in smoke detector to safeguard human life.

Force Controlled Low Cycle Fatigue (LCF) Life Evaluation Methodology Based on Unstabilized Material Properties

Low Cycle Fatigue (LCF) is a prominent failure mechanism in many design components; therefore, an evaluation of cycles to failure in this regime is of high importance. Most international standards recommend a closed loop strain-controlled mode specimen testing in this regime. However, the ꜪN data obtained from this test is not suitable for life evaluation of parts enduring force-controlled history during actual service without correction for control mode. Many existing procedures, which accounts for cyclic strain stabilization during force-controlled loading may significantly complicate the finite elements analysis (FEA) at solving or post processing stages and are often an inherent source of uncertainty. A heuristic, cost effective and sufficiently accurate approach for LCF life estimation is advocated. The method involves only two force loading FEA simulations, one of the actual parts and the other of the test specimen, using initial unstabilized stress strain curve, followed by a limited number of force-controlled specimens testing. Actual part and specimen life correlation performed using first loading unstabilized equivalent plastic strain value Ꜫp1 under locality and similitude assumptions. Unstabilized strain vs. number of cycles to failure curve Ꜫp1N is constructed and discussion regarding specimen geometry considerations for providing sufficient accuracy is included. Method validation and crack propagation study are provided.

Bridge Resistance Updating Based on the General Particle Simulation Algorithms of Complex Bayesian Formulas

The existing bridges are subjected to time-variant loading and resistance degradation processes. How to update resistance probability distribution functions with resistance degradation model and proof load effects has become one of the research hotspots in bridge engineering field. To solve with the above issue, this paper proposed the general particle simulation algorithms of complex Bayesian formulas for bridge resistance updating. Firstly, the complex Bayesian formulas for updating resistance probability model are built. For overcoming the difficulty for the analytic calculation of complex Bayesian formulas, the general particle simulation methods are provided to obtain the particles of complex Bayesian formulas; then, with the improved expectation maximization optimization algorithm obtained with the combination of K-MEANS algorithm and Expectation Maximization (EM) algorithm, the above simulated particles can be used to estimate the posteriori probability density functions of resistance probability model; finally, a numerical example is provided to illustrate the feasibility and application of the proposed algorithms.

Comparative Study of Electric Machines for Stirling Generator Application

The choice of a machine for an application and a given specification remains a complex problem. This will involve, for example, bringing together criteria such as: performance, space saving, economical, reliable, little acoustic noise and others. The best machine selection to fulfill all constraints is an important step for the project to be realized. This work focus on Stirling Engine based Generator and study all types of rotating machines that can be employed for maximum electric power production. Analytical electromagnetic models where developed for all types of rotating machines that satisfied minimum requirement for the project by solving Maxwell equations. The purpose is to develop the design model and combine electromagnetic and thermal study of the machines. Finite Element Method is used to compare the performances of the generators for the best choice. Results show that for applications not requiring bigger output power, the major criteria for the selection is the optimal magnetic induction created by the inducer in the stationary part of the machine. For application such as Stirling generators, permanent magnet (PM) machine satisfy many comparison criteria such as maximum power at low speed, torque density, high efficiency. Beyond exposing a selection method for a project, this work lay down a step-by-step method for engineers and scientists for the crucial stage of design and conception work