Hashmi H.N.,UET Taxila
International Journal of Environmental Research | Year: 2011
Feasibility of methanolic wastes treatment containing chlorophenol in experimental UASB reactors i. e. R-I and R-II working side by side constantly for a couple of almost 32 weeks were studied. UASB reactor R-I was initiated by utilizing the digested sludge alone, whereas, the UASB reactor R-II was startedup by adding an activated carbon of an effective size 1. 5-2. 5mm to the digested sludge with the volume-volume ratio of 3:2. At low loading rates d'' 0. 5g-TOC/L-d for R-I and d'' 2. 6g-TOC/L-d for R-II, it was observed that the effect of HRT on the TOC reduction was not prominent, and in both the reactors the TOC reduction effectiveness was noticed to be above 80%. An optimum OLR to accomplish 80-85% TOC and chlorophenol reduction effectiveness (at HRT e'' 12hours) was observed to be 2. 6g-TOC/L-day and 10. 8g-TOC/L-day for reactor R-I and R-II, respectively. It was also observed that to attain more than 80% TOC removal efficiency at a constant OLR of 6. 5g-TOC/L-day and at a HRT of 18-20hours, the maximum influent chlorophenol concentration should stay below 21mg/L and 29mg/L for reactor R-I and R-II, respectively. The average VFAs effluent concentration observed was 357mg/L and 230mg/L for the reactor R-I and R-II, respectively. Comparatively the production of biogas in reactor R-II was less. The overall gas conversation rate observed at greater than 80% TOC removal efficiency for R-I and R-II was found to be 0. 28L/g-COD removed and 0. 17L/g-COD removed, respectively, with 60-62% of methane content for both the reactors. The results of this study suggested that the use of methanol as a medium to biodegrade chlorophenol in the presence of an activated carbon in a UASB reactor is an effective and feasible method at mesophilic temperature and neutral pH.
Imtiaz H.,UET Taxila |
Mahfouz F.M.,Menoufia University
CMES - Computer Modeling in Engineering and Sciences | Year: 2015
This paper investigates numerically the conjugate heat transfer in a concentric enclosure that is formed between two concentric cylinders and filled with micropolar fluid. The wall of inner cylinder is considerably thick, while the wall of outer cylinder is very thin. The inner cylinder is heated from inner side through constant heat flux, whereas the outer cylinder is cooled and maintained at constant temperature. The induced buoyancy driven flow and associated conjugate heat transfer are predicted numerically by solving flow and energy governing equations considering a combination of finite difference and Fourier spectral methods. The study investigates the effect of controlling parameters on both flow and thermal fields, keeping focus on inner wall temperature. The controlling parameters are Rayleigh number Ra, dimensionless thickness of inner wall, inner cylinder fluid thermal conductivity ratio Kr, and material parameters of micropolar fluid (λ, B and D). The study shows that the steady dimensionless mean inner wall temperature φI decreases with increase in Kr and Ra, and decrease in the vortex viscosity D. The study also shows that the increase in thickness of inner wall at Kr < 1 leads to increase in steady φI . While in case of Kr > 1, for a given value of Ra and D, φI assumes maximum value at certain thickness of inner wall. In general, the study demonstrates that, for same geometrical and flow parameters, φI is more in case of micropolar fluids as compared to Newtonian fluids. Copyright © 2015 Tech Science Press.
Imtiaz H.,UET Taxila |
Mahfouz F.M.,Menoufia University
Heat and Mass Transfer/Waerme- und Stoffuebertragung | Year: 2014
This paper investigates numerically the conjugate heat transfer in an annulus between two concentric cylinders. The annulus contains micropolar fluid and is heated isothermally from its inner wall. The effect of Rayleigh number, thickness of inner wall, inner wall-fluid thermal conductivity ratio, and material parameters of micropolar fluid on heat transfer rate within the annulus has been investigated. The study has shown that for low Rayleigh number regimes and for thermal conductivity of the inner wall greater than that of the fluid, the increase of inner wall thickness increases the heat transfer rate through the annulus and vice versa. While for convection dominating regimes Ra ≥ 104 the increase of inner wall thickness decreases the heat transfer rate. Moreover, the study has shown that for fixed geometrical and flow parameters the heat transfer decreases in case of micropolar fluids in comparison with that of Newtonian fluids. © 2013 Springer-Verlag Berlin Heidelberg.
Ali S.,French Atomic Energy Commission |
Ghani U.,UET Taxila |
Life Science Journal | Year: 2013
The present paper presents results from an experimental work in an open channel flow. The open channel contains a weir-like obstruction with different leeward slopes. Two discharge values have been used under subcritical flow conditions. The objective of the present study is to investigate the flow behavior behind a vegetated obstacle. The characteristics explored included the turbulent kinetic energy and recirculation zone behind the vegetated obstacles. It was observed from this work that the TKE has higher values in recirculation regions. On the other hand it was also found to be of high intensity in the vegetated zones of the flow. However TKE was maximum and positive close to the bed at a section at the end of the weir crest and it was negative below the top of the vegetation dowels. As far as recirculation region was concerned, it was observed that the vegetation had no effect on the recirculation zone behind the vegetated weir. In case of weir with mild downstream slope (1:7), the flow separation zone vanished and the energy head loss in this case decreased due to the decrease in form drag of the weir.
Sheikh N.A.,Mohammad Ali Jinnah University |
Manzoor S.,UET Taxila |
Ali M.,UET Taxila
Advances in Condensed Matter Physics | Year: 2015
Granular flows in vibrated bed exhibit various physical phenomena primarily driven by vibrating base. As the vibrating surface is the only source of energy in an otherwise dissipative flow, most of the theoretical models relate the steady state energy input to the RMS velocity of vibration. Here variation of heat flux is studied at varying frequency of vibration while keeping the RMS vibration velocity and the cell loading constant. Using single particle analysis and MD simulations, an extended version of grain-base collision is observed resulting in the reduction of heat flux at lower frequencies (<50 Hz) of vibration. The presented findings are important as most experimental studies are reported at these frequencies of excitation. © 2015 Nadeem Ahmed Sheikh et al.
PubMed | COMSATS Institute of Information Technology, King Saud University, UET Taxila and Institute of Management Sciences
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2016
In this paper, a novel routing strategy to cater the energy consumption and delay sensitivity issues in deep underwater wireless sensor networks is proposed. This strategy is named as ESDR: Event Segregation based Delay sensitive Routing. In this strategy sensed events are segregated on the basis of their criticality and, are forwarded to their respective destinations based on forwarding functions. These functions depend on different routing metrics like: Signal Quality Index, Localization free Signal to Noise Ratio, Energy Cost Function and Depth Dependent Function. The problem of incomparable values of previously defined forwarding functions causes uneven delays in forwarding process. Hence forwarding functions are redefined to ensure their comparable values in different depth regions. Packet forwarding strategy is based on the event segregation approach which forwards one third of the generated events (delay sensitive) to surface sinks and two third events (normal events) are forwarded to mobile sinks. Motion of mobile sinks is influenced by the relative distribution of normal nodes. We have also incorporated two different mobility patterns named as; adaptive mobility and uniform mobility for mobile sinks. The later one is implemented for collecting the packets generated by the normal nodes. These improvements ensure optimum holding time, uniform delay and in-time reporting of delay sensitive events. This scheme is compared with the existing ones and outperforms the existing schemes in terms of network lifetime, delay and throughput.
Arshad A.,National University of Sciences and Technology |
Hashim N.H.,UET Taxila
International Journal of Environmental Research | Year: 2012
Two UASB reactors R-I and R-II, each of 10liters capacity, made up of acryl material were operated parallel and continuously for a period of 220 days, using actual effluent of the NSSC pulp and paper mill, at mesophilic temperature and neutral pH. The main objective was to investigate the treatability performance of the reactors at varying OLR and HRT in terms of TOC and lignin removal. The reactor R-I was used by conventional procedure, whereas, for the reactor R-II methanol and activated carbon was added to supplement its efficiency. Corresponding to an optimum OLR of 4.5kg/m3-day and HRT of 18hrs, the reactor R-II gives 69% TOC and 60% lignin removal. But, in the reactor R-I at same operating conditions, only 56% TOC and 51% lignin removal was noticed. However, the biogas yield in the reactor R-I was noticed relatively more than in the R-II. The biogas yield observed was 0.28m3/kg-CODrem and 0.18m3/kg-CODrem in the reactor R-I and R-II, respectively, with 56-58% methane content in both the reactors. The average VFAs concentration observed in the reactor R-I and R-II is 360mg/L and 230mg/L, respectively. The results of this study suggest that the use of methanol and activated carbon to enhance the treatability efficiency of the UASB reactor is a viable option for the treatment of NSSC pulping effluent.
Jalil A.,CESAT |
Yousaf H.,CESAT |
Baig M.I.,UET Taxila
Proceedings of 2016 13th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2016 | Year: 2016
In radar the reflected signal is received by the antenna which is amplified, down converted and then the required signal is extracted (video signal). The video signal is then passed through Moving Target Indicator (MTI) processor which suppresses clutter. The post-MTI data is passed through Constant False Alarm Rate (CFAR) processor which qualifies echoes as targets or otherwise. The role of CFAR processor is to determine a threshold, above which any return can be considered to be from target. If this threshold is too low, more targets will be detected at the expense of more false alarms. Conversely, if the threshold is set too high, then fewer targets will be detected but the number of false alarms will be less. The distribution of the clutter can be approximated by certain probability distribution functions, where each medium follows a different probability distribution. We shall investigate important CFAR processing techniques in Gaussian noise and Rayleigh clutter. The threshold is set adaptive, that is the threshold is raised or lowered, to maintain a required Probability of False Alarm (PFA). This paper discusses various CFAR processing techniques, by applying them to raw video of real radar, analyzing advantages and disadvantages of each technique. © 2016 IEEE.
Ali A.,UET Taxila |
Ali M.,UET Taxila
Multidimensional Systems and Signal Processing | Year: 2016
This paper presents an identification method for spatially interconnected distributed systems operating in closed-loop. The proposed approach makes use of refined instrumental variable method to identify spatially interconnected systems in Box–Jenkins form, where the controller is assumed to be known. The method presented here can yields statistically optimal estimates, and compared with other approaches to identify such systems under similar scenarios, takes far less time. The approach is applicable to both separable and non-separable systems and takes into account the boundary conditions. Though described only for two-dimensional systems, it is readily extendible to systems having more spatial dimensions. The effectiveness of the method is shown by a simulation example. © 2016 Springer Science+Business Media New York
Nasreen S.,UET Taxila |
Azam M.A.,UET Taxila |
Shehzad K.,UET Taxila |
Naeem U.,University of East London |
Ghazanfar M.A.,UET Taxila
Procedia Computer Science | Year: 2014
Pattern recognition is seen as a major challenge within the field of data mining and knowledge discovery. For the work in this paper, we have analyzed a range of widely used algorithms for finding frequent patterns with the purpose of discovering how these algorithms can be used to obtain frequent patterns over large transactional databases. This has been presented in the form of a comparative study of the following algorithms: Apriori algorithm, Frequent Pattern (FP) Growth algorithm, Rapid Association Rule Mining (RARM), ECLAT algorithm and Associated Sensor Pattern Mining of Data Stream (ASPMS) frequent pattern mining algorithms. This study also focuses on each of the algorithm's strengths and weaknesses for finding patterns among large item sets in database systems. © 2014 The Authors.