Adaptive differential amplitude pulse-position modulation technique (DAPPM) using fuzzy logic for optical wireless communication channels

In the past few years, people have become increasingly demanding for high transmission rate, using high-speed data transfer rate, the number of user increased every year, therefore the high-speed optical wireless communication link have become more popular. Optical wireless communication has the potential for extremely high data rates of up to tens of Gigabits per second (Gb/s). An optical wireless channel is usually a non-directed link which can be categorized as either line-of-sight (LOS) or diffuses. Modulation techniques have attracted increasing attention in optical wireless communication, therefore in this project; a hybrid modulation technique named Differential Amplitude Pulse-Position Modulation (DAPPM) is proposed to improve the channel immunity by utilizing optimized modulation to channel. The average symbol length, unit transmission rate, channel capacity, peak-to-average power ratio (PAPR), transmission capacity, bandwidth requirement and power requirement of the DAPPM were determined and compared with other modulation schemes such as On-Off Key (OOK), Pulse-Amplitude Modulation (PAM), Pulse-Position Modulation (PPM), Differential Pulse-Position Modulation (DPPM), and Multilevel Digital Pulse Interval Modulation (MDPIM). Simulation result shows that DAPPM gives better bandwidth and power efficiency depending on the number of amplitude level (A) and the maximum length (L) of a symbol. In addition, the fuzzy logic module is developed to assist the adaptation process of differential amplitude pulse-position modulation. Mamdani fuzzy logic method is used in which the decisions made by the system will be approaching to what would be decided by the user in the real world

Numerical and experimental study of hydrodynamics in a compartmented fluidized bed oil palm shell biomass gasifier

Numerical and experimental studies of hydrodynamic parameters of fluidized beds formed by either a single component system or a binary mixture in a pilot plant scale model of a Compartmented Fluidized Bed Gasifier (CFBG) have been performed. The numerical study is carried out with an Eulerian-Eulerian description of both gas and particle phases and a standard drag law for multiphase interaction. The numerically simulated results are then compared with the experimental results.The 2D and 3D flow patterns of the combustor and the gasifier are first generated from the numerical study to observe the bubble formation, possible channeling behavior and the binary mixing patterns in the bed.For a single component system, detailed 3D numerical analyses and experimental studies are done to investigate the bed expansion ratio, bubble diameter, bed pressure drop, and fluidization quality in CFBG. Two types of Geldart B inert particles namely river sand and alumina are used in the study.All trends of the aforementioned studies are well-predicted with the numerical values not greater than 15% of the recorded experimental values. Good fluidization is attainable in the combustor side, while the pressure drop behaviour seen for the gasifier with river sand shows that channelling occurs in the bed. The channelling behaviour becomes more severe with alumina bed.The solid circulation rate (SCR) is numerically simulated in this study as well. Solid circulation rate (SCR) increases with the increase in bed height while the main bed aeration does not affect the SCR which is consistent with the experimental data.For a binary mixture system with palm shell and river sand as the second fluidizing material, detailed 3D numerical analysis of the bed expansion ratio is done in parallel with the experimental study. The results of numerical predictions of overall mixing quality and local mixing index are verified by comparing with the experimental results. The actual trends of the studies are modestly captured by the numerical model with under-predicted values of less than 20%. The overall binary mixing quality is enhanced with the smaller palm shell size and larger palm shell weight percent. In addition, increasing the superficial gas velocity increases the local binary mixing index in the experiment.From the studies on bed expansion, bubble formation, steady equilibrium state and overall binary mixing quality, the 2D model provides well over-predicted values compared to the 3D flow model. Also, the local mixing index of the binary system is not captured by the 2D model. The numerical values predicted by 3D model are closer to the actual values.The key findings from the aforementioned studies are used as a guide to develop and operate the pilot plant scale CFBG with 0.5 ton/day of palm shell feed for fuel gas production

Hydrodynamics of binary mixture fluidization in a compartmented fluidized bed

The paper represents an extensive study of hydrodynamic cahracteristics of a fluidized bed in a pilot-plant-scale fluidized bed reactor designed for syngas production and power generation from biomass as a source of renewable energy. An air-blown compartmented fluidized bad gasifier permitting heat transfer between adjacent discrete compartments via solid circulation consists of two compartments, the combustor and the gasifier, operating at bubbling fluidized mode. Results of numerical simulation of the fluidized bed containing monodisperesed size Geldart B particles are represented. A three-dimensional Eulerian-culerian granualr model with closure laws according to the kinetic theory of granular flow is chosen to simulate the multipahse environs at 0.2 - 3.2 times minimum fluidization velocity. The present work reports also experimental results on the fluidization of palm-shell-sand binary mixtures of 2, 5, 10 and 15 wt % of feedstock including the minimum fluidization velocity of palm shell-sand binary mixtures, fluidization quality for different bed diameter, particle size, bed height, and superficial velocity. The velocity and lateral palm shells distributions in the mixtures are discussed

An engineered wetlands system for septage treatment in Malaysia

Septage from the individual septic tanks is pumped out periodically to maintain their performances. Septage treatment was carried out in a pilot system comprising two stages of vertical-flow engineered wetlands (VFEWs). This research project has confirmed that high treatment performance is achievable by the VFEWs system to treat raw septage, with suitable coupling of system design (plant presence, type; substrate type) and operational practices (solid and hydraulic loading rate; dosing frequency; pond and rest period)

Gamification: motivating users’ energy conservation behaviour

The energy issues such as energy shortage, high energy price, environmental problems and so forth have long become the world concern. Previous research pointed that, energy issues are much related to human behaviour and subsequently can be improved through promotion of better energy use behaviour. Therefore, this paper intends to introduce a concept known as gamification, to motivate the engagement of the users in conserving energy through a fun and enjoyable environment. Gamification is defined as the use of game design elements in a non-game context to create a fun environment to promote particular behaviour. In game play environment, we can always see a common scenario of players tend to have high engagement and attachment to game playing. This is due to some elements in game context created the fun playing environment to the game players. So, gamification is a concept that intends to apply those elements that normally exist in game (which called game design elements) in the non-game context to create fun environment for promoting particular behaviour. Previously this concept has been proven effective in motivating the engagement of the users’ on particular behaviour. Thus researcher has carried out a preliminary review on previous relevant studies to identify the relevant game design element for application of gamification in energy saving context. This paper will present the most common game design elements extracted from previous relevant studies and few examples will be provided as a reference for application of gamification in promoting and motivating energy saving behaviour

Local and global messages for prompting energy conservation behaviour: an experimental study in university

To create a cost effective environment during the management of building facilities, energy conservation is important among building users as it can help to conserve energy and reduce energy cost. To promote energy conservation, the behavior of user should be focused where their behavior should be improved to reduce energy wastage. Prompt is among the simplest and inexpensive behavioural interventions to improve energy conservation behavior. The prompt has been used wisely in healthcare sectors to promote healthy lifestyles, but no recent study on energy conservation behavior. The aim of this research was to investigate the effectiveness of prompt in prompting energy conservation behavior among the building users in university. An experiment was designed and carried out to examine the effectiveness of local and global types prompt messages for prompting efficiency use of energy. This research findings show that there was no significant difference between local and global types prompt messages, however, the findings indicate that both prompt messages were able to prompt the behavior change among the energy users and local type prompt message was more able to prompt the users than global types prompt messages. This finding could provide the useful information to society nowadays on using prompt to manage the energy efficiently

An efficient of overlapping grid method with scattering technique in time domain for numerical modeling

An Overlapping Grid Method (OGM) with Biquadratic Spline Interpolation in scattering technique was developed to solve the direct and inverse scattering issues. A two-dimensional (2D) numerical image model was used to analyze the accuracy of the proposed method in a direct scattering process. It was discovered that when the sub-grid, sxΔ increased, the absolute error for the electric field amplitude will also increase. The results also discovered that as the grid size ratio increased, the absolute error of the amplitude ZE will also increase. The findings show that smaller grid spacing and a finer grid size can produce more accurate results. The Overlapping Grid Method (OGM) with Biquadratic Spline Interpolation was expanded by incorporating with Forward-Backward Time Stepping (FBTS) technique to solve inverse scattering issues. Homogenous embedded objects with a square and circular shape are used to validate the efficiency of the proposed method. The findings showed that the proposed numerical method could detect and reconstruct embedded objects in different shapes. The efficiency of the proposed method was examined by Mean Square Error (MSE) and normalizing the functional error. The findings revealed that the MSE of dielectric profiles for the proposed method were lower than the FDTD method in FBTS. The relative permittivity and conductivity profile differed by 27.06% and 20%, respectively. Hence, it was proven that the proposed method successfully solved a known drawback to the FDTD method and produced more accurate and efficient results