Multimedia Environmental Fate and Transport Model of dichlorodiphenyltrichloroethane (DDT): Case Study Sayong River Watershed, Johor, Malaysia

This study describes the development of a multimedia environmental fate and transport model of dichlorodiphenyltrichloroethane (DDT) at Sungai Sayong watershed. Based on the latest estimated DDT emission, the DDT concentrations in air, soil, water and sediment as well as the transfer processes were simulated under the equilibrium and steady-state assumption. Model predictions suggested that soil and sediment was the dominant sink of DDT. The results showed that the model predicted was generally good agreement with field data. Compared with degradation reaction, advection outflow was more important processes occurred in the model. Sensitivities of the model estimates to input parameters were tested. The result showed that vapour pressure (Ps) and organic carbon water partition coefficient (KOC) were the most influential parameters for the model output. The model output-concentrations of DDT in multimedia environment is very important as it can be used in future for human exposure and risk assessment of organochlorine pesticides (OCPs) at Sungai Sayong Basin

Characterising lateral capacitance of MNOSFET with localised trapped charge in nitride layer

This paper discusses the limitations of scanning microscope to read localised charge and proposes a viable solution. A 2D simulation and characterisation of the capacitance-voltage (C-V) characteristics of the lateral source-base transition of metal-nitride-oxide-semiconductor field effect transistor (MNOSFET) with charge trapped in nitride layer is presented. It is shown that C-V dependence is changed after trapping the localised charge in nitride layer. The change depends on position of the localised trapped charge. An n-channel transistor is considered with acceptor concentration in base of 1016 cm−3. By localising a charge bit with linear size of 80 nm in nitride layer, it is observed that capacitance jump in C-V dependence starts at some bias voltage applied to the source-base transition. This voltage depends on the position of charge bit. This dependence can be used in determining the charge bit position in the nitride layer along channel. To the best of the author’s knowledge, it is one of the most efficient methods in scanning localised charge

Modeling and implementation of photovoltaic modules for a DC-DC Boost Converter

A photovoltaic (PV) system is a renewable energy system intended to convert sunlight into the usable electricity. Due to the rapid world infrastructure development, the demand for electricity is increasing drastically. One of the promising energy resources is the PV. The required energy demand can be provided by the increase of PV system deployment. Thus, as part of the design, development and implementation of a new PV system, a system design simulation is essential. This is to ensure that the designed system works properly according to design specifications. For this reason, a PV mathematical model is necessary in the development process of the PV system especially in the MATLAB/Simulink software environment. With the developed PV model, the PV system design and simulation is made handy, thus escalates the future energy demand. This work describes the development of the PV mathematical model in the MATLAB/Simulink software environment based on the PV related equations. The equations are formed by the consideration of the equivalent circuit of PV cell. The developed PV model characteristics such as the Power-Voltage (P-V) and Current-Voltage (I-V) curves are obtained as the simulation output in MATLAB/Simulink. The obtained characteristics are compared to the actual PV model A 100W RNG-50D Renogy, as to verify the effectiveness and closeness of the developed PV model to the real PV module. In addition, in the simulation, a dc-dc boost converter is also designed and integrated with the PV model as to verify the PV module and capability as a PV power source. The simulation results with the dc-dc boost converter DC-DC integration have shown that the developed PV model is very effective to be used for the PV system simulation

An All-Optical Frequency Up/Down-Converter Utilizing Stimulated Brillouin Scattering In A Trf And Dcf For Rof Application

A frequency up and down conversion is proposed based on stimulated Brillouin scattering (SBS) for Radio-over-fiber (RoF) system. Microwave frequency up conversion from 2GHz to 12.5GHz and microwave frequency down conversion from 12.5GHz to 1.8GHz with largest Intermediate Frequency (IF) power of -32dBm is successfully demonstrated. The up conversion is based on the 1st Stokes of Brillouin fiber laser in Truewave reach fiber (TWF) and the down conversion is based on 1st AntiStokes of Brillouin fiber laser in Dispersion compensating fiber (DCF)

Development Of Aquaponic System Using Solar Powered Control Pump

This paper describes the development of an aquaponic system using solar panel to control the water pump and air pump based on Peripheral Interface Controller (PIC) technology. Solar power is ideally can be used in Malaysia due to location factor and also give the benefit to the environment as renewable energy. It involves a combination of electrical, electronics and agriculture into one sustainable system which consists of a solar panel, inverter, water pump and air pump. The solar panel is the most cleanest ways to produce electricity. With the average output voltage is 12V while the maximum output voltage produce by the solar panel is 18 V. The voltage depends on light capture by solar panel. Weather can minimize the light capture by solar panel thus affect the overall performance. This project requires a substitution power grid with green energy from solar panel which an inverter is used to convert Direct Current (DC) to Alternate Current (AC) and to step up 12V to 110V or 240V. A microcontroller is used to control the operation of an aquaponic system for switching water pump, air pump, battery charge and discharge state. Based on observation, the output power from inverter has produced 65.55% efficiency and the average output voltage of the solar panel is 16.16 V

120 nm wide band switchable fiber laser

A novel method of producing switchable tunable output that spans the S-, C- and L-bands is presented. The achievable tuning range is about 120 nm. The design consists of a wide band SOA, 1 x 16 AWG and an optical selectable switch in a ring configuration. The measured average output powers for S-. C- and L-bands for different output wavelengths are -7.0 dBm, -6 dBm and -6.5 dBm respectively. The SMSR for these wavelengths is about 72 dB. (C) 2010 Elsevier BM. All rights reserved

Multi-wavelength fiber laser in the S-band region using a Sagnac loop mirror as a comb generator in an SOA gain medium

A simple design of multi-wavelength generation in the S-band region of the optical network transmission is proposed. The design consists of broad-band fiber Bragg grating (BB-FBG), which acts as a filter to enhance operation in the S-band region. A Sagnac loop mirror (SLM) is used to generate multiple wavelength oscillations in the ring cavity. The output consists of 60 lasing wavelengths oscillating simultaneously between 1464 nm and 1521 nm with a spacing of 0.92 nm and an output linewidth of 0.66 nm

Wavelength conversion based on four-wave mixing in a highly nonlinear fiber in ring configuration

An efficient system for generating the four-wave mixing (FWM) effect in a short length of a highly nonlinear fiber (HNLF) is demonstrated using a ring configuration, which to our knowledge is the first of its kind to be reported. The conversion efficiency obtained is –4 dB for a HNLF length of 100 m when pumped with a 90 mW diode pump laser at 1490 nm in ring configuration which is the highest ever reported. The signal-to-noise (SNR) ratio is 43 dB. The conversion efficiency and SNR are flat over a span of 20 nm and can provide an effective means of wavelength conversion for telecommunication applications