Mehran University of Engineering and Technology informally: Mehran University) , is a public research university located in Jamshoro, Sindh, Pakistan. In its neighborhood is located the Sindh University and Liaquat University of Medical and Health science; it is one of the premier institution of higher learning in the country with a strong focus on industrial management and engineering. Wikipedia.
Hashmani A.A.,University of Duisburg - Essen |
Hashmani A.A.,Mehran University of Engineering and Technology |
Erlich I.,University of Duisburg - Essen
International Journal of Electrical Power and Energy Systems | Year: 2012
This paper presents the design of local decentralized power system stabilizer (PSS) controllers, using selected suitable remote signals as supplementary inputs, for a separate better damping of specific inter-area modes, for large-scale power systems. System identification technique is used for deriving lower order state-space models suitable for control design. The lower-order model is identified by probing the network in open loop with low-energy pulses or random signals. The identification technique is then applied to signal responses, generated by time-domain simulations of the large-scale model, to obtain reduced-order model. Lower-order equivalent models, thus obtained, are used to design each local PSS controller separately for each of the inter-area modes of interest. The PSS controller uses only those local and remote input signals in which the assigned single inter-area mode is most observable and is located at a generator which is most effective in controlling that mode. The PSS controller, designed for a particular single inter-area mode, also works mainly in a frequency band given by the natural frequency of the assigned mode. The locations of the local PSS controllers are obtained based on the amplitude gains of the frequency responses of the best-suited measurement to the inputs of all generators in the interconnected system. For the selection of suitable local and supplementary remote input signals, the features or measurements from the whole system are pre-selected first by engineering judgment and then using a clustering feature selection technique. Final selection of local and remote input signals is based on the degree of observability of the considered single mode in them. To provide robust behavior, H ∞ control theory together with an algebraic Riccati equation approach has been applied to design the controllers. The effectiveness of the resulting PSS controllers is demonstrated through digital simulation studies conducted on a sixteen-machine, three-area test power system. © 2012 Elsevier Ltd. All rights reserved.
Siddiqui F.I.,Mehran University of Engineering and Technology |
Osman S.B.A.B.S.,Petronas University of Technology
Environmental Earth Sciences | Year: 2013
Precise determination of engineering properties of soil is essential for proper design and successful construction of any structure. The conventional methods for determination of engineering properties are invasive, costly and time-consuming. Electrical resistivity survey is an attractive tool for delineate subsurface properties without soil disturbance. Reliable correlations between electrical resistivity and other soil properties will enable us to characterize the subsurface soil without borehole sampling. This paper presents the correlations of electrical resistivity with various properties of soil. Soil investigations, field electrical resistivity survey and laboratory electrical resistivity measurements were conducted. The results from electrical resistivity tests (field and laboratory) and laboratory tests were analyzed together to understand the interrelation between electrical resistivity and various soil properties. The test results were evaluated using simple and multiple regression analysis. From the data analysis, significant quantitative and qualitative correlations have been obtained between resistivity and moisture content, friction angle and plasticity index. Weaker correlations have been observed for cohesion, unit weight of soil and effective size (D 10). © 2012 Springer-Verlag Berlin Heidelberg.
Khahro S.F.,Beijing Institute of Technology |
Tabbassum K.,Information Technology Center |
Soomro A.M.,Beijing Institute of Technology |
Soomro A.M.,Mehran University of Engineering and Technology |
And 2 more authors.
Energy Conversion and Management | Year: 2014
Pakistan is currently experiencing an acute shortage of energy and urgently needs new sources of affordable energy that could alleviate the misery of the energy starved masses. At present the government is increasing not only the conventional energy sources like hydel and thermal but also focusing on the immense potential of renewable energy sources like; solar, wind, biogas, waste-to-energy etc. The recent economic crisis worldwide, global warming and climate change have also emphasized the need for utilizing economic feasible energy sources having lowest carbon emissions. Wind energy, with its sustainability and low environmental impact, is highly prominent. The aim of this paper is to explore the wind power production prospective of one of the sites in south region of Pakistan. It is worth mentioning here that this type of detailed analysis is hardly done for any location in Pakistan. Wind power densities and frequency distributions of wind speed at four different altitudes along with estimated wind power expected to be generated through commercial wind turbines is calculated. Analysis and comparison of 5 numerical methods is presented in this paper to determine the Weibull scale and shape parameters for the available wind data. The yearly mean wind speed of the considered site is 6.712 m/s and has power density of 310 W/m2 at 80 m height with high power density during April to August (highest in May with wind speed 9.595 m/s and power density 732 W/m2). Economic evaluation, to exemplify feasibility of installing wind turbines, is also done. The estimated cost of per kWh of electricity from wind is calculated as 0.0263 US$/kWh. Thus the candidate site is recommended for some small stand-alone systems as well as for wind farm. © 2013 Elsevier Ltd. All rights reserved.
Memon R.A.,Mehran University of Engineering and Technology |
Leung D.Y.C.,University of Hong Kong
Environmental Fluid Mechanics | Year: 2011
This study investigates the impact of building aspect ratio (building-height-to-street-canyon-width-ratio), wind speed and surface and air-temperature difference (Δθs-a) on the heating environment within street canyon. The Reynolds-averaged Navier-Stokes (RANS) and energy transport equations were solved with Renormalization group (RNG) theory version of k-turbulence model. The validation process demonstrated that the model could be trusted for simulating air-temperature and velocity trends. The temperature and velocity patterns were discussed in idealized street canyons of different aspect ratios (0.5-2.0) with varying ambient wind speeds (0.5-1.5 m/s) and Δθs-a (2-8 K). Results show that air-temperatures are directly proportional to bulk Richardson number (Rb) for all but ground heating situation. Conversely, air-temperatures increase significantly across the street canyon with a decrease in ambient wind speed; however, the impact of Δθs-a was negligible. Clearly, ambient wind speed decreases significantly as it passes over higher AR street canyons. Notably, air-temperatures were the highest when the windward wall was heated and the least during ground heating. Conversely, air-temperatures were lower along the windward side but higher within the street canyon when the windward wall was heated. © 2010 The Author(s).
Ursani A.A.,Mehran University of Engineering and Technology |
Kpalma K.,INSA Rennes |
Lelong C.C.D.,CIRAD - Agricultural Research for Development |
Ronsin J.,INSA Rennes
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012
A new procedure is proposed for agricultural land-use mapping that addresses a known weakness of classical per-pixel methods in situations involving mixed tree crops. The proposed scheme uses a pair of very-high resolution satellite-borne panchromatic and multispectral images and integrates classification results of two parallel and independent analyses, respectively based on spectral and textural information. The multispectral image is divided into spectrally homogeneous but non-contiguous segments using unsupervised classification. In parallel, the panchromatic image is split into a grid of square blocks on which is performed a texture-driven supervised classification. Finally, the spectral and the textural classifications are fused to generate the land-use map. This method contrasts with object-based methods that sequentially perform image segmentation and classification. Results are evaluated both quantitatively and qualitatively, based on field survey ground-truth data. The quantitative assessment is presented in terms of overall accuracy (from 80% to 100% depending on the area) and Kappa coefficients. Visual comparison of the resulting map with the ground-truth is performed, with the analysis of the binary error maps. Merging spectral and textural classifications results in finer border delimitation and improves the overall classification accuracy of agricultural land-use by 27% as compared to textural classification alone. © 2011 IEEE.
Umrani A.W.,Mehran University of Engineering and Technology |
Guan Y.L.,Nanyang Technological University |
Umrani F.A.,Mehran University of Engineering and Technology
Progress in Electromagnetics Research | Year: 2010
A comparative analysis of transmit diversity and beam-forming for linear and circular antenna arrays in a wireless communications system is presented. The objective is to examine the effect of random perturbations, angular power distributions on transmit diversity and beamforming system. The perturbations are modeled as additive random errors, following complex Gaussian multivariate distribution, to the antenna array steering vectors. Using outage probability, probability of error, and dynamic range of transmitter power as performance measures, we have shown significant effects of array perturbations on the two systems under spatially correlated Rayleigh fading channel. We also examine the effect of angular power distributions (uniform, truncated Gaussian, and truncated Laplacian), which corresponds to different propagation scenario, on the performance of the two systems. Results show that the central angle-of-arrival can have signi-cant impact on system performance. And the transmit di-versity system with truncated Laplacian distribution performs better as compared to other power distributions, and linear array is a prefer-able con-guration for transmit diversity system. We conclude that array perturbations must not be neglected in the design of transmit diversity and beamforming systems.
Khatri A.,Mehran University of Engineering and Technology |
Peerzada M.H.,Mehran University of Engineering and Technology |
Mohsin M.,Faisalabad Campus |
White M.,RMIT University
Journal of Cleaner Production | Year: 2015
Most cotton fabrics are dyed with reactive dyes because they produce a full range of bright fashion colours with a high degree of wash fastness. Application of these dyes, however, causes high and undesirable levels of dissolved solids and oxygen demand in the effluent. This is due to the use of considerable quantities of inorganic salt and alkali to ensure efficient utilisation and fixation of the reactive dyes. Dye that is unfixed on cotton also contributes to effluent pollution. There are two approaches to deal with the effluent problem: 1. alternative dyeing techniques and technology, 2. effluent treatment after dyeing. The effluent treatment requires additional capital investment and high treatment and maintenance costs. Therefore, the first approach is always preferable. There have been a number of options developed to overcome the polluted effluent problem of dyeing cotton fabric with reactive dyes. This paper reviews the options to improve sustainability of the dyeing process through development of reactive dyes, modification of dyeing machinery and processes, chemical modification of cotton fibre prior to dyeing, use of biodegradable organic compounds in dyebath formulation, and effluent treatment processes. The paper highlights the significance and limitations of these ways of improving sustainability in reactive dyeing, and proposes the areas for further improvements. © 2014 Elsevier Ltd. All rights reserved.
Khatri Z.,Mehran University of Engineering and Technology |
Memon M.H.,TEXCON Textile Consulting Services |
Khatri A.,Mehran University of Engineering and Technology |
Tanwari A.,Mehran University of Engineering and Technology
Ultrasonics Sonochemistry | Year: 2011
Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with -OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength (K/S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values ΔE (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample. © 2011 Elsevier B.V. All rights reserved.
Memon A.J.,Mehran University of Engineering and Technology |
Shaikh M.M.,Mehran University of Engineering and Technology
Energy | Year: 2016
Power crisis is a sensitive issue which can handicap activities of any country at large. In Pakistan, industries consume the majority of energy, of which 28% is the electrical energy. About 30-80% of the electrical energy consumed by industries is due to electric motors. This study aims to promote electrical energy conservation in industries of Pakistan by presenting benefits of replacing existing standard efficiency motors through EEMs (energy efficient motors). A sample of existing SMs (standard motors) obtained by surveying some industries of Pakistan is used for statistical analysis. The benefits of EEMs are emphasized in terms of annual energy savings, cost savings and paybacks. By using t-distribution, 90% confidence bounds for these parameters are constructed. It is found that future replacements of SMs by EEMs, will achieve an average energy saving of atleast 1009.747 kWh/year and atmost 3404.047 kWh/year, and an average cost saving of atleast Rs. 10859.719/year and atmost Rs. 33550.065/year. The average payback period would be between 0.177796 and 0.265912 years. The sensitivity analysis of the results is provided. The presented confidence bounds can be used to encourage the government and financers for the large scale replacement of SMs by EEMs to conserve electrical energy sufficiently in Pakistan industries. © 2016 Elsevier Ltd.
Memon R.A.,Mehran University of Engineering and Technology |
Leung D.Y.C.,City University of Hong Kong
Journal of Environmental Sciences | Year: 2010
This study investigated the impact of important environmental variables (i.e., wind speed, solar radiation and cloud cover) on urban heating. Meteorological parameters for fifteen years (from 1990 to 2005), collected at a well developed and densely populated commercial area (Tsim Sha Tsui, Hong Kong), were analyzed in details. Urban heat island intensity (UHII), a well known indicator of urban heating, has been determined as the spatially averaged air-temperature difference between Tsim Sha Tsui and Ta Kwu Ling (a thinly populated rural area with lush vegetation). Results showed that the UHII and cloud cover have increased by around 9.3% and 4%, respectively, whereas the wind speed and solar radiation have decreased by around 24% and 8.5%, respectively. The month of December experienced the highest UHII (10.2°C) but the lowest wind speed (2.6 m/sec) and cloud cover (3.8 oktas). Conversely, the month of April observed the highest increases in the UHII (over 100%) and the highest decreases in wind speed (over 40 %) over fifteen years. Notably, the increases in the UHII and reductions in the wind speed were the highest during the night-time and early morning. Conversely, the intensity of solar radiation reduced while the intensity of urban cool island (UCII) increased during solar noon-time. Results demonstrated strong negative correlation between the UHII and wind speed (coefficient of determination, R2 = 0.8) but no negative correlation between UCII and solar radiation attenuation. A possible negative correlation between UHII and cloud cover was investigated but could not be substantiated. © 2010 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences.