Showing papers by "Shafiqul Islam published in 2016"

A question driven socio-hydrological modeling process

Abstract: . Human and hydrological systems are coupled: human activity impacts the hydrological cycle and hydrological conditions can, but do not always, trigger changes in human systems. Traditional modeling approaches with no feedback between hydrological and human systems typically cannot offer insight into how different patterns of natural variability or human-induced changes may propagate through this coupled system. Modeling of coupled human–hydrological systems, also called socio-hydrological systems, recognizes the potential for humans to transform hydrological systems and for hydrological conditions to influence human behavior. However, this coupling introduces new challenges and existing literature does not offer clear guidance regarding model conceptualization. There are no universally accepted laws of human behavior as there are for the physical systems; furthermore, a shared understanding of important processes within the field is often used to develop hydrological models, but there is no such consensus on the relevant processes in socio-hydrological systems. Here we present a question driven process to address these challenges. Such an approach allows modeling structure, scope and detail to remain contingent on and adaptive to the question context. We demonstrate the utility of this process by revisiting a classic question in water resources engineering on reservoir operation rules: what is the impact of reservoir operation policy on the reliability of water supply for a growing city? Our example model couples hydrological and human systems by linking the rate of demand decreases to the past reliability to compare standard operating policy (SOP) with hedging policy (HP). The model shows that reservoir storage acts both as a buffer for variability and as a delay triggering oscillations around a sustainable level of demand. HP reduces the threshold for action thereby decreasing the delay and the oscillation effect. As a result, per capita demand decreases during periods of water stress are more frequent but less drastic and the additive effect of small adjustments decreases the tendency of the system to overshoot available supplies. This distinction between the two policies was not apparent using a traditional noncoupled model.

Time-Temperature Model for Bacterial and Parasitic Annihilation from CowDung and Human Faecal Sludge: A Forthcoming Bio-Fertilizer

Abstract: The present study investigated the optimum time and temperature for inactivation of bacteria and parasites in cow dung and pit faecal sludge, a forthcoming fertilizer. Samples were collected from different areas of Bangladesh and were examined through modified centrifugal flotation and conventional culture techniques to isolate parasites and bacteria respectively. A cow dung sample from Gopalganj and a pit sample from Dohar that were found to be the most contaminated among the samples tested were heated to annihilate the pathogens present there. After 30 min of exposure at 60°C, all bacteria lost their ability to grow on culture media except enterococci. Among the parasites found in the pit sample, Entamoeba histolytica was the least heat resistant, which was killed at 60°C within 30 min followed by Ancylostoma duodenale larva, Strongyloides stercoralis larva, Trichuris trichiura, Ancylostoma duodenale eggs and Strongyloides stercoralis egg. Ascaris lumbricoides and Hymenolepis nana were the most resistant to heat, inactivated at 75°C within 15 min. In cow dung, Paramphistomum was the most resistant, became inactivated at 65°C within 60 min whereas Haemonchus at 65°C within 30 min. The study findings showed the best time dependent temperature to deactivate the pathogens present in faecal sludge in Bangladesh context.

Adaptive Control for Robot Manipulators using Multiple Parameter Models

Abstract: In this paper, we propose multiple parameter models based adaptive switching control system for robot manipulators. We first uniformly distribute the parameter set into a finite number of smaller compact subsets. Then, distributed candidate controllers are designed for each of these smaller compact subsets. Using Lyapunov inequality, a candidate controller is identified from the finite set of distributed candidate controllers that best estimates the plant at each instant of time. The design reduced the observer-controller gains by reducing modeling errors and uncertainties via identifying an appropriate control/model via choosing largest guaranteed decrease in the value of the Lyapunov function energy function. Compared with CE based CAC design, the proposed design requires smaller observer-controller gains to ensure stability and tracking performance in the presence of large-scale modeling errors and disturbance uncertainties. In contrast with existing adaptive method, multiple model based distributed hybrid design can be used to reduce the energy consumption of the industrial robotic manipulator for large scale industrial automation by reducing actuator input energy. Finally, the proposed hybrid adaptive control design is experimentally tested on a 3-DOF PhantomTM robot manipulator to demonstrate the theoretical development for real-time applications.

Bilateral shared autonomous system for MUMAV with nonpassive human and environment input interaction forces

Abstract: In this paper, the stability and synchronization control problem of bilateral shared autonomous system for miniature unmanned multirotor aerial vehicle (MUMAV) is addressed with nonpassive human and environment input forces. The master input interface design combines scaled position of the master manipulator with velocity signals of the MUMAV and reflected remote interaction forces. The slave input interaction interface is designed by combining scaled position and velocity of the master manipulator with the velocity of the remote slave MUMAV system. The data transmission between local master and remote MUMAV is assumed to be carried out by using dedicated internet communication network with negligible time delay. The convergence analysis is shown by using Lyapunov method. The analysis shows that the closed loop bilateral shared autonomous system is input-to-state stable and ultimately bounded with nonpassive human and environment input interaction force.

A Simple Streamflow Forecasting Scheme for the Ganges Basin

Abstract: To increase preparedness and improve response to floods in Bangladesh, a streamflow forecasting lead time of 7–10 days is desired at the international border entry points of the major rivers. The accuracy of available streamflow forecast products is currently limited to 3–5 days, which is much shorter than the desired lead time for floods. Several initiatives continue to develop and refine hydrologic and flood forecasting models without adequately exploring the utility of precipitation forecasts to obtain longer flood forecasting lead time. For large basins with a strong seasonality, such as the Ganges, simple but carefully designed linear regression models may provide great value to operational flood forecasting. Here, a simple linear model with observed streamflow and gridded precipitation data for the upstream basin areas is introduced to provide satisfactory forecasts for the Ganges flow at the Hardinge Bridge point with up to 10-day lead time. The proposed linear model can provide 3- to 5-day forecasting lead time using only lagged values of flow with skill comparable to published results of detailed hydrological or statistical models. The results also suggest that 5–6 days forecasted rainfall and observed streamflow are able to enhance streamflow forecasting accuracy for a lead time up to 10 days. The proposed framework can be of great value to operationalize flood forecasting in large basins, where upstream data are scarce or inaccessible due to political boundaries, and detailed forecasting model setups are prohibitively expensive.

Output feedback impedance reflection based bilateral shared autonomous system without input force measurement

Abstract: In this paper, we investigate output feedback based control strategy for bilateral shared autonomous system with delay. The proposed design has two parts. In first part, we design state feedback based shared input interface provided that all the states are available for feedback. In second part, we replace the unknown velocity signals by using observer to develop output feedback based shared input under delay. The convergence condition with observer based output feedback design is shown by using the singularly perturbed method. The analysis shows that the performance achieved under state feedback can be recovered by using output feedback as the values of observer gains converge to zero. Finally, Experimental results are given to demonstrate the validity of the theoretical argument of the proposed design for real-time applications.

Adaptive output feedback control for miniature unmanned aerial vehicle

Abstract: In this paper, we address output feedback control problem for miniature unmanned aerial vehicle (MUAV). We first design state feedback based nonlinear control by assuming that states are available for feedback. Then, we use observer to estimate the velocity signals to develop output feedback based nonlinear controller for MUAV. The convergence condition with output feedback design is given by Lyapunov method. The analysis shows that the performance achieved under state feedback can be recovered by using output feedback as the values of observer gain converges to zero. Evaluation results are presented to demonstrate the validity of the theoretical argument of the proposed design for real-time applications.

Oral Nystatin: An Effective Prophylaxis for Fungal Infection in Preterm Babies in a Tertiary Level Hospital

Abstract: Introduction: Candida is a common cause of oral mucous membrane and skin infections in newborn infants and an important cause of neonatal morbidity and mortality. Methods: This Quasi experimental study was carried out in NCU, Department of Paediatrics, Sir Salimullah Medical College Mitford Hospital, Dhaka, over a period of 16months, to find out the efficacy of oral Nystatin in reducing colonization of fungus and fungaemia in preterm babies admitted in NCU. One hundred sixty consecutive preterm babies admitted in NCU within 72 hours of birth fulfilling the inclusion criteria were enrolled. Every alternate baby was taken as case and another was taken as control and the first one selected by lottery. Case group received oral Nystatin prophylaxis 1lacs unit 6 hourly for five days and control group given usual NCU care without antifungal prophylaxis. Babies were examined daily. Swab from oral mucous membrane was collected for gram staining, wet film preparation for direct microscopy and culture for fungus and blood culture for fungus and bacteria. Results: The mean age of enrolled babies was 23.9±19.3 hours in case and 19.3±17.8 hours in control groups. Both the groups were similar regarding GA, sex, mode of delivery, anthropometry, duration of antibiotics uses, and mean hospital stay. Gram staining, wet film preparation with 20% KOH for direct microscopic examination and culture of oral swab and blood culture of cases & controls at baseline and follow up revealed no Candida or any other fungus. However, Gram staining of oral swab revealed Gram positive cocci both in case and control groups at base line and at follow up which was not significant. Both oral swab culture and Blood culture developed growth of various organisms without any fungus both in case and in controls at base line and at follow up, which was also not significant. Conclusion & Recommendations: The present study revealed that Gram staining of oral swab, wet film preparation and culture of oral swab and blood at baseline and at follow up, 5 days after enrollment did not grow any fungus in both cases and controls. So Nystatin prophylaxis in the case was of no use in preventing oral colonization of fungus and fungaemia. For generalization of this hypothesis further multicenter study with a large sample size and longer duration of follow up is required. Methods: This Quasi experimental study was carried out in NCU, Department of Paediatrics, Sir Salimullah Medical College Mitford Hospital, Dhaka, over a period of 16months, to find out the efficacy of oral Nystatin in reducing colonization of fungus and fungaemia in preterm babies admitted in NCU. One hundred sixty consecutive preterm babies admitted in NCU within 72 hours of birth fulfilling the inclusion criteria were enrolled. Every alternate baby was taken as case and another was taken as control and the first one selected by lottery. Case group received oral Nystatin prophylaxis 1lacs unit 6 hourly for five days and control group given usual NCU care without antifungal prophylaxis. Babies were examined daily. Swab from oral mucous membrane was collected for gram staining, wet film preparation for direct microscopy and culture for fungus and blood culture for fungus and bacteria.Introduction: Candida is a common cause of oral mucous membrane and skin infections in newborn infants and an important cause of neonatal morbidity and mortality. Methods: This Quasi experimental study was carried out in NCU, Department of Paediatrics, Sir Salimullah Medical College Mitford Hospital, Dhaka, over a period of 16months, to find out the efficacy of oral Nystatin in reducing colonization of fungus and fungaemia in preterm babies admitted in NCU. One hundred sixty consecutive preterm babies admitted in NCU within 72 hours of birth fulfilling the inclusion criteria were enrolled. Every alternate baby was taken as case and another was taken as control and the first one selected by lottery. Case group received oral Nystatin prophylaxis 1lacs unit 6 hourly for five days and control group given usual NCU care without antifungal prophylaxis. Babies were examined daily. Swab from oral mucous membrane was collected for gram staining, wet film preparation for direct microscopy and culture for fungus and blood culture for fungus and bacteria.

Torque reflecting coordination control for bilateral shared autonomous system over open communication networks

Abstract: In this paper, torque reflection based coordination control algorithm is designed for network-based bilateral shared autonomous system over open communication networks. The control algorithm for master and slave manipulator is designed by combining delayed position and velocity signal with the delayed reflected torques from the interaction between human and master and between slave and environment. Robust and adaptive control technique is used to deal with uncertainty associated with the gravity, unmodeled dynamic and other external input disturbance. The convergence of the closed loop system is shown by using Lyapunov method. In contrast with existing force reflection based design, the proposed controller can deal with uncertainty associated with the gravity, unmodeled dynamic and external input disturbance. Compared with other methods, the proposed design uses reflected torques from the interaction between master and human and between slave and environment so as to improve the transparency of the bilateral shared autonomous system. Finally, evaluation results are presented to demonstrate the validity of the proposed design for real-time applications.

Robust coordination control interface for networked based telerobotic system

Abstract: In this paper, we propose coordination control interface for transparent networked telerobotic system under delay and bounded uncertainty. The coordination control input interface for the master manipulator combines delayed positionvelocity signals with the delayed estimated impedance properties of the interaction between slave and remote environment. The delayed position-velocity signals of the master manipulator are used to develop input interaction interface for slave manipulator. The master and slave input interface design also employs with the local position and velocity signal of the master and slave manipulator. Both master and slave input interface uses adaptive terms locally to estimate the interaction properties between human and master manipulator and between slave and remote environment. To deal with the uncertainty associated with the unmodeled dynamic and external input disturbance, robust term combined locally with adaptive control term. Using Lyapunov analysis, the stability condition is derived in the presence of delays. Finally, evaluation results are presented to demonstrate the effectiveness of the proposed input interface for real-time applications.