Multimedia environmental fate and transport model of dichlorodiphenyltrichloroethane (DDT): case study sayong river watershed

This study describes the development of a multimedia environmental fate and transport model of dichlorodiphenyltrichloroethane (DDT) at Sayong River Watershed. Based on the latest estimated DDT emission, the DDT concentrations in air, soil, water, and sediment as well as the transfer flux were simulated under the equilibrium and steady-state assumption. Model predictions suggest 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 in removal processes of DDT. Sensitivities of the model estimates to input parameters were tested. The result showed that vapour pressure (Ps), chemical solubility (Cs), and absolute temperature (T) of DDT 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 Sayong River Basin

Velocity control of a unicycle type of mobile robot using optimal pid controller

A unicycle model of control a mobile robot is a simplified modeling approach modified from the differential drive mobile robots. Instead of controlling the right speed, VR and the left speed, VL of the drive systems, the unicycle model is using u and ω as the controller parameters. Tracking is much easier in this model. In this paper, the dynamic of the robot parameter is controlled using two blocks of Proportional-Integral-Derivative(PID) controllers. The gains of the PID are firstly determined using particle swarm optimization(PSO) in offline mode. After the optimal gain is determined, the tracking of the robot’s trajectory is performed online with optimal PID controller. The achieved results of the proposed scheme are compared with those of dynamic model optimized with genetic algorithm(GA) and manually tuned PID controller gains. In the algorithm, the control parameters are computed by minimizing the fitness function defined by using the integral absolute error(IAE) performance index. The simulation results obtained reveal advantages of the proposed PSO-PID dynamic controller for trajectory tracking of a unicycle type of mobile robot. A MATLAB-Simulink program is used to simulate the designed system and the results are graphically plotted. In addition, numerical simulations using 8-shape as a reference trajectory with several numbers of iterations are reported to show the validity of the proposed scheme

Determinants of Economic Exposure: an Empirical Evidence From the Miscellaneous Companies in Indonesia

This research empirically measures the economic exposure of 11 selected miscellaneous companies in Indonesia. It also attempts to empirically explore the influence of firm size, export, liquidity, and leverage on the economic exposure of those companies. Annual data from 2007 to 2010, which was collected from thewww.idx.co.id andwww.bi.go.id were used and analyzed by the multiple linear regression to measure the economic exposure and examine the influences of the firm size, export, liquidity, and leverage on the economic exposure. Both partial (t-test) and simultaneous (F-test) hypotheses were constructed and tested using the software of SPSS for Windows. The research documented that, with the exception of the liquidity, which has a negative and significant effect partially on the economic exposure, all other variables, i.e., the firm size, export, and leverage were found to have insignificant effects. Meanwhile, based on the F-test, the research found that the firm size, export, liquidity, and leverage affected simultaneously and significantly the economic exposure of the companies. These findings imply that in order to manage their economic exposure, the companies should control these variables, especially the liquidity

An evaluation of heat loss on top of solar collector with multilayered absorber in solar water heating system

Solar water heating system is one of the applications of solar energy. One of the components of solar water heating system is solar collector that consists of an absorber. The heat loss to the surroundings is in important factor in the determination of performance of the solar collector. The smaller value of heat losses to the surrounding will result the higher performance of the solar collector. Thus, this study is conducted to evaluate the heat loss of top of solar collector with multilayered absorber in solar water heating system. Methods used in this paper include solar collector with multilayered absorber is tested and evaluated by examining the heat loss at top of solar collector in solar water heating system. The results show the impact to the solar water heating system is indeed predictable where multilayered absorber in solar collector is proven to play its main role when it able to keep the hot water temperature longer at minimum amount of 176.4 W/unit area as for heat loss

In situ synthesis of hydroxyapatite-grafted titanium nanotube composite

The present study is an investigation to demonstrate the effectiveness of insitu approach in the synthesis of hydroxyapatite-grafted titanium nanotube composite (HA-TNT). This method involves combining the process of HA sol–gel and rapid breakdown anodisation of titanium in a novel solution consisting of NaCl and N3PO4. This new synthesis approach produced a uniform dispersion of Anatase and Rutile phases of TiO2 nanotubes with minimal agglomeration in the matrix of crystalline HA. The characterisation of homogenised HA-TNT composite was investigated via field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM) and X-ray diffraction (XRD). FESEM and TEM images indicated the nanostructure of composite with TiO2 nanotube diameter of approximately 10 nm. XRD and EDS analyses confirmed the formation of HA crystalline with the Ca/P ratio of 1.58 and formation of Anatase and Rutile phase of TiO2 nanotubes

A study on V-shaped microstrip patch MIMO antenna

A study on the V-shaped microstrip patch antenna for multiple-input multiple-output (MIMO) communication system based on the antenna orientation is performed. First the microstrip patch antenna operating at 2.45 GHz is calculated and simulated. Next, multiple elements of antennas for MIMO system is simulated and discussed. V-shaped with 45 degree slanted inward and outward is studied. The antenna properties are analyzed and compact antenna design is determined based on the simulation results. The dresults show the gap between antennas can be optimized to 1 mm while maintaining low mutual coupling. The gain of the MIMO antenna is 8.42 dBi. The simulated return losses, together with the radiation patterns, are presented and discussed

Reconfigurable Metamaterial Structure at Millimeter Wave Frequency Range

In this paper, reconfigurable metamaterial structure at millimeter wave frequency range was designed and simulated for a future fifth generation (5G) mobile-phone beam switching applications. The new proposed structure was composed of a bridge-shaped resonator (BSR) in the front face and strip line at the back face of the unit cell which operates at 28 GHz. First, non-reconfigurable low loss BSR unit cell was designed and subsequently, the reconfigurability was achieved using four switches formed in the gaps of the structure. The proposed structure achieves the lowest loss and almost full transmission among its counterparts by -0.06 dB (0.99 in linear scale). To demonstrate the reconfigurability of the metamaterial, the reflection and transmission coefficients and real parts of the effective refractive index at each reconfigured frequency were studied and investigated. Simulation results showed that a high transmission and reflection peaks occur at each resonance frequency according to change the state of the switches

Improvement in measurement accuracy for hybrid scanner

The capability to provide dense three-dimensional (3D) data (point clouds) at high speed and at high accuracy has made terrestrial laser scanners (TLS) widely used for many purposes especially for documentation, management and analysis. However, similar to other 3D sensors, proper understanding regarding the error sources is necessary to ensure high quality data. A procedure known as calibration is employed to evaluate these errors. This process is crucial for TLS in order to make it suitable for accurate 3D applications (e.g. industrial measurement, reverse engineering and monitoring). Two calibration procedures available for TLS: 1) component, and 2) system calibration. The requirements of special laboratories and tools which are not affordable by most TLS users have become principle drawback for component calibration. In contrast, system calibration only requires a room with appropriate targets. By employing optimal network configuration, this study has performed system calibration through self-calibration for Leica ScanStation C10 scanner. A laboratory with dimensions of 15.5m x 9m x 3m and 138 well-distributed planar targets were used to derive four calibration parameters. Statistical analysis (e.g. t-test) has shown that only two calculated parameters, the constant rangefinder offset error (0.7mm) and the vertical circle index error (-45.4inch were significant for the calibrated scanner. Photogrammetric technique was utilised to calibrate the 3D test points at the calibration field. By using the test points, the residual pattern of raw data and self-calibration results were plotted into the graph to visually demonstrate the improvement in accuracy for Leica ScanStation C10 scanner

Predictor-Corrector Modified Line Search Strategies for Solving Systems of Nonlinear Equations

Diagonal updating scheme is among the cheapest Newton-like methods for solving system of nonlinear equations. Nevertheless, the method has some shortcomings. In this paper, we proposed an improved matrix-free secant updating scheme via line search strategies, by using the steps of backtracking in the Armijo-type line search as a step length predictor and Wolfe-Like condition as corrector. Our approach aims at improving the overall performance of diagonal secant updating scheme. Under mild assumptions, the global convergence results have been presented. Numerical experiments verify that the proposed approach is very promising