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

Engine performance and exhaust emission of diesel dual fuel engine fuelled by biodiesel, diesel and natural gas

The performance and exhaust emission of 6 cylinder four stroke direct injection diesel dual fuel (DDF) engine were investigated, the duel fuel used is corn oil methyl esters consist of 5%, 10%, 15% and 20% blends with diesel and compressed natural gas (CNG). Experiment was conducted at a fixed compression ratio of 17.5:1 with variance of engine speed 1400, 1800, 2400 and 2600 rpm. Combination of Biodiesel and CNG showed a better result on engine performance in terms of horse power and engine torque compared to other types of tested fuel. The substantial decrease of 25.6 % in exhaust emission flue was observed, giving lower value of UHC and nitrogen oxide (NOx). However, when the fuel is blended with CNG, a poor performance on exhaust emission was recorded, which include carbon dioxide (CO2), carbon monoxide (CO), unburned hydrocarbon (UHC) and nitrogen oxide (NOx) due to presence of CNG in fuel

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

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

Systematic review and stratified meta-analysis of the efficacy of carnosine in animal models of ischemic stroke

Carnosine is a naturally occurring pleotropic dipeptide which influences multiple deleterious mechanisms that are activated during stroke. Numerous published studies have reported that carnosine has robust efficacy in ischemic stroke models. To further evaluate these data, we have conducted a systematic review and meta-analysis of published studies. We included publications describing in vivo models of ischemic stroke where the neuroprotective efficacy of carnosine was being evaluated through the reporting of infarct volume and/or neurological score as outcomes. Overall efficacy was evaluated using weighted mean difference random effects meta-analysis. We also evaluated for study quality and publication bias. We identified eight publications that met our inclusion criteria describing a total of 29 comparisons and 454 animals. Overall methodological quality of studies was moderate (median ¼ 4/9). Carnosine reduced infarct volume by 29.4% (95% confidence interval (CI), 24.0% to 34.9%; 29 comparisons). A clear dose-response effect was observed, and efficacy was reduced when carnosine was administered more than 6 h after ischemia. Our findings suggest that carnosine administered before or after the onset of ischemia exhibits robust efficacy in experimental ischemic stroke. However, the methodological quality of some of the studies was low and testing occurred only in healthy young male animals

Cause-specific child mortality in a mountainous community in Pakistan by verbal autopsy

In Pakistan\u27s rural areas population-based cause of death data from systematic verbal autopsies are rare. Using verbal autopsy algorithms with multiple coding and decision rules, we assigned causes of death among 79% of children under age five years dying between July, 1988 and December, 1991 in Oshikhandass, a remote mountainous community in Pakistan\u27s Northern Areas. Main causes of death were pneumonia (44%), diarrhoea (35%), and neonatal sepsis (6%). Combined (main plus associated) analysis revealed 48% died with diarrhoea, 46% with malnutrition, 44% with pneumonia, 15% with neonatal sepsis, and 15% with low birth weight. Median age of death with pneumonia was 2 months, with diarrhoea 8 months. Half died by month 4. The inquiry was well received by villagers. Population-based verbal autopsy surveillance is a cost-effective strategy to guide health managers. Plans are underway to institute it for the surrounding population of 400,000. Creative ways to access, treat and reduce risk among young infants are needed

Appendicitis with appendicular atresia: A rare presentation

Acute appendicitis is the most common acute surgical condition; making appendectomy the most commonly performed emergency surgical procedure in the world. Anomalies of the appendix are relatively  uncommon. However, their presence may alter the course of pre-operativediagnosis and the surgical treatment provided, leading to medico-legal issues in certain cases as well. We hereby present the case of a 17  year-old female who had the suggestive signs, symptoms and  investigations of appendicular lump. She was managed according to the Ochsner-Sherren regimen and then underwent interval open appendectomy 6 weeks later. During the procedure, the findings of a 5 cm long appendix were noted. The base of the appendix was attached to the caecum, however there was complete mucosal discontinuity between the base and the remaining portion of the appendix. A fibrous strand connected the two blind ending parts together. After thorough literature search, the authors concluded that this is only the fourth reported case of appendicular atresia ever to have been reported. Considering the rarity of this finding we feel this could be of valuable interest to surgeons and readers alik

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