Mehran University Research Journal of Engineering and Technology

6

Authors: Muhmammad Rafique Daudpoto; Mir Ghulam Haider Talpur; Feroz Shah; Aijaz Khooharo

Regression is a statistical method that is generally used for forecasting and prediction. It helps us to estimate the relationship between a dependent variable and one or more independent variables. This is the most widely used technique that best approximates the individual data points. It has found numerous successful applications in Engineering, Science, business and other fields. Getting average removal % of Biological Oxygen Demand (BOD5) from greywater through Rotating Biological Contactor (RBC), following experiment was conducted in Sindh University hostels using different parameters such as Hydraulic Retention Time (HRT) i.e. 2 hours (0.42 liter per min), 2.5 hours (0.33 l/min) and 3 hours (0.28 l/min) and multiple number of discs i.e. 40, 42, 44, 46, 48, 50 and 52. Consequences reveal that linear estimate of HRTs and numbers of disc are considerable whereas linear and quadratic estimates of number of discs are highly significant, which evidence the significance of time and discs. However, as p-value is greater than 0.05, hence quadratic estimate of HRT is not significant. By using coefficients of the table the regression equation is Removal = - 79.995 + 6.88 time + 2.90 disc, where the sample standard deviation is 7.151, coefficient of correlation is 0.86 and coefficient of determination is 0.742. Distributions of errors are approximately normal as probability plot of the residuals is approximately linear. Residual analysis shows that against each predicted variable, residuals plot falls approximately in a horizontal band symmetric and centered about the horizontal axis and against predicted y-values. Moreover, Residual plot shows the constant standard deviations and linearity assumptions appear to be met.

7

Authors: Faheem Akhtar; Mansoor Ahmed; Muhammad Naeem Akhtar

The quality of water is of the utmost importance and vital concern for the human beings since it has a direct link with the human health and welfare. If the drinking water or tap water gets contaminated, it can result in severe health problems. For example, if the drinking water contains over the limit amount of fluoride then it can lead to bone deterioration and other bone related problems. The purpose of the present study is to carry out quality analysis of drinking and tap water in Nawabshah City. The analyzed parameters are pH, TDS, Total Alkalinity, Total Hardness, Calcium Hardness and Electrical Conductivity. World Health Organization (WHO) standards are followed in the present study. Total 18 drinking water and tap water samples were collected from 6 different locations in Nawabshah City. The parameters that appeared to be within the limits are PH and total alkalinity whereas TDS, total hardness, calcium hardness and electrical conductivity crossed WHO standard limits at some locations.

8

Authors: Kamran Shah; Hassan Khurshid; Izhar Ul Haq; Shaukat Ali Shah; Zeeshan Ali

In manufacturing or production setup, maintenance cost is one of the major portions of overall operating expenditure. It can vary between 15 to 60 percentage of overall cost for various industries including food related industries, iron, steel and other heavy industries. Such a high cost directly impacts manufacturing setup, profitability and sustainability in long run. In most of the industries, ineffective maintenance management can result in loss of capital and inefficient human resource deployment. This in turn affects the plants’ ability to manufacture quality products that are competitive in the market. Various maintenance management strategies including Operate to Failure (OTF), Design Out Maintenance (DOM), Skill Level Upgrade (SLU), Condition Based Monitoring (CBM) and Fixed Time Maintenance (FTM) are used in industries for maximizing productivity. In recent years, Computerized Maintenance Management System (CMMS) has become an integral part of most of the industries so its importance and characteristics cannot be understated. While CMMS cannot live standalone, it requires some decision-making techniques to be equipped with. These techniques range from Failure Mode and Effect Analysis (FMEA) to Decision Making Grid (DMG). In this paper, concept of DMG has been applied to an automotive parts Manufacturing Industry in conjunction with Weibull analysis. Parallels are drawn between the results of DMG and Weibull analysis.

9

Authors: Abdul Waheed; Nizamud Din; Arif Iqbal Umar; Riaz Ullah; Noor Ul Amin

To make the electoral process more secure, comfortable, and universal, it is essential to use modern cryptographic techniques for ensuring the anonymity of information in the electronic voting system. In many emerging applications like electronic voting data anonymity as well as un-traceability are the most essential security properties. To ensure these properties we present here in this paper a more secure and comparatively efficient blind signcryption scheme using the Elliptic Curve Cryptosystem (ECC). The existing e-voting schemes are based on El-Gamal and the Rivest-Shamir-Adleman (RSA) cryptosystems which are not only expensive approaches but also lack the security features like unlinkability and forward secrecy. In our proposed scheme we use a low-cost elliptic curve cryptosystem with 160 bits key as compared to El-Gamal 2048 bits key and RSA 1024 bits key. In this scheme signer signs the message blindly without knowing the original contents then the voter forward signcrypted vote to polling server. The polling server is the actual voter data verifier or validator. The polling server checks the validity/authenticity of the voter and has the right to accept or reject the vote. Moreover, this scheme offers forward secrecy, unlinkability, and non-repudiation in addition to the basic security features like confidentiality, authenticity, integrity, and unforgeability. Overall performance evaluation proves that our scheme is comparatively more efficient in terms of computational and communicational costs. Furthermore, this scheme is suitable for the e-voting system due to its lower cost and extra security features.

9

Authors: Sohail Muhammad; Humair Ahmed Siddiqui; Muhammad Ishaque Abro; Adil Usmani; Muhammad Amjad Anwar Mallick

Cement mortar, which is one of the most useful materials for construction applications, can deteriorate its performance by developing cracks. In order to cope with this issue, the materials’ scientist came forward with a unique biogeochemical phenomenon in which cement mortar can selfheal its crack autonomously using calcium carbonate precipitating bacteria and their feed. In this research, it was intended to study the separate and combined effect of Bacillus Subtilis (bacteria) and Calcium Lactate (feed) on the properties of conventional mortar. Cement mortars were made using conventional method and cast in the form of cylinders. Four types of samples were taken. Sample-N contains only cement and sand, Sample-B was made by addition of bacteria Bacillus Subtilis with sand and cement, Sample-C contains Calcium Lactate which is usually used as feed for Bacteria while the last sample ‘BC’ have both Bacteria as well as Calcium Lactate. The samples were observed up to 44 days for their surface characteristics and compressive strength. The Sample-N and B did not show any remarkable change in their surface appearance with respect to curing time. Sample-C and BC did show the precipitation of CaCO3 but the Sample-C precipitation was stopped soon while for Sample-BC, the precipitation was continued for a longer time. The Sample-BC showed the highest compressive strength (approximately 17.57 MPa), followed by Sample-N (approximately 13.32 MPa), Sample-B (approximately 11.04 MPa) while Sample-C displayed lowest strength (approximately 2.75 MPa). This gives an idea that Calcium Lactate which acts as feed for bacteria has the negative effect on the strength if not consumed and converted into CaCO3.

11

Authors: Muhammad Hamza; Syed Mashhad M. Geelani; Qamar Nawaz; Asif Kabir; Isma Hamid

The Internet of Things (IoT) has emerged as a new paradigm, and billions of devices are connected with the internet. IoT is being penetrated in major domains of daily life like health care, agriculture, industry, smart homes and monitoring of the environment. The operator of such complex, huge and diverse heterogeneous networks may not even be fully aware of their IoT devices working, activity, behavior and resource utilization etc. The efficient management of IoT devices becomes a challenge for network managers to ensure smooth network operation. Network traffic analysis of IoT devices is a necessary and rudimentary tool to understand the behavior of devices. In this paper firstly, we identify insights of device network traffic, discuss the activity patterns of some IoT devices and present a visual description of the pattern of IoT devices. Secondly, after analyzing the device's behavior, we build and demonstrate a profile of each device based on its activity cycle and traffic patterns information. Thirdly, the K-Means clustering algorithm is used to make clusters of IoT devices using their profile information. The clustering algorithm groups similar devices in a single group. The obtained results clearly describe the patterns of devices which help the network managers to make appropriate network policies for efficient secure network management.

12

Authors: Umair Khadim; Muhammad Munwar Iqbal; Muhammad Awais Azam

Digital text is the most frequent interchange form of data that could hold sensitive information such as audit firms, banks, and educational institutes. This sensitive information needs to preserve its integrity and originality so that it could not only secure the data but also helps to identify ownership of text documents. This paper presents a novel and invisible digital watermarking approach for the secure exchange of text documents over the internet. Digital watermarking serves from the last decade for detection of forgery and tempering from digital text documents and maintained the copyright and authentication successfully. Many states of the art watermark techniques achieve high imperceptibility, robustness, and high hidden capacity; unfortunately failed to maintain the balance among these three conflicting parameters. As resolvent, we propose an intelligent Three-Level Digital Watermarking (3LDW) system for text documents copyright protection. 3LDW system can be applied to Microsoft Word objects, document open spaces, and text feature coding without affecting the content of the original document. Experimental results reveal that our proposed 3LDW system strongly resist against formatting attacks and efficiently preserves the imperceptibility. Additionally, embedding capacity analysis demonstrates a prominent improvement of the proposed system as compared to other similar approaches.

12

Authors: Rabia Noreen Gul1a, Aftab Ahmad; Saqib Fayyaz; Muhammad Kashif Sattar; Syed Saddam ul Haq

This paper presents the solution of highly complex, non-linear, multi-objective Dynamic Combined Economic Emission Dispatch (DCEED) problem. DCEED is a power system optimization problem with conflicting objectives of fuel cost and emission. DCEED includes constraints like valve point loading effect, Transmission Losses and Ramp Rate limits. Solution of DCEED problem is given by a novel Hybridized Flower Pollination Algorithm (FPA) with Sequential Quadratic Programming (SQP). FPA is a nature inspired population based meta-heuristic optimization technique that models its search on the flower pollination process. The non-convex nature of generation because of numerous operational, physical and dynamic constraints, makes search space highly multi model and complex. This makes DCEED a challenging as well as an attractive problem for research. The effectiveness of FPA-SQP is tested and validated by applying it on IEEE Standard 5-unit and 10- unit non-convex test system in MATLAB environment for the time interval of 24 hours. The results achieved by this algorithm show significant reduction in cost and emission as compared to other available techniques in the literature.

14

Authors: Sumera Ahmad; Suraya Miskon

Textile and Apparel (T&A) industry is the backbone of Pakistani economy, including one-fourth of the industrial sector, and comprises 40% of industrial employees and approximately 60% share of Pakistani exports. Although, industry is striving hard to compete in international market; a persistent stream of innovation is required to maintain its due share in recent quota free global trade of textiles. Business Intelligence (BI) system is one of the most-used buzzwords in the modern business landscape for well informed decision making. In spite of the great synergies and benefits, BI system grant to the businesses and organizations. The adoption level is low with high failure ratio, especially in developing countries. Further, researchers did not propose any theory or model for the T & A industry. This study aims to fill this gap by conducting a Systematic Literature Review (SLR) for identifying the most appropriate factors, theory and model for the current study. Total of 75 studies were selected which were published during the period of 2011- 2020. A conceptual model is developed with most potential factors by using Technology-Organization Environment (TOE) framework. This conceptual model will guide the policy makers and industry practitioners to integrate and adopt the BI system successfully that would helpful to achieve competitive edge in the international business markets.

16

Authors: Caroline A. Sobo; Sadia Farooq; Salman Azhar

Concrete, a material that can be used as a building material and at the same time when mixed with light source, can enhance the beauty of a space as well as open new ways to experiment with it. The vision behind the research is to contribute with the manufacturers who are having “vision of cities that glow from within” through the use of concrete embedded with optic fiber strands. The aim of this research is to determine light transmitting properties of translucent concrete embedded with plastic fiber optics. In this experimental study, the amount of light is calculated that is able to transmit through the concrete. The four concrete blocks of equal size but different in amounts of plastic fiber optic strands are made. The research concluded that the fiber optics has the good light guiding properties which allow light to pass through the concrete in sufficient amount. The concrete with plastic fiber optics is named as translucent concrete, provides endless varieties of applications, not only aesthetically pleasing, but it can also promote safety, privacy and security as well as integrate the idea of saving green energy in the construction industry.

7

Authors: Shahid Hussain Abro

It is common practice that formation of second phase particles such as nitrides or carbides in the steel matrix has significant role to control the grain size of steel. An attempt is made in the present research work to find out the role of nitrogen to form the nitride particles either with Al, Ti, B, Cr or Si. Two steel samples Steel-A and Steel-B with same titanium and aluminum weight percent in the chemical composition were obtained in hot rolled conditions from international market with only the difference of presence of Niobium in Steel-A. Solution heat treatment was performed at 1350°C with 60 minutes holding time in protherm heat treatment furnace available locally was used to dissolve the particles and then steel samples were reheat treated at 800°C with holding time of 60 minutes and water quenched and microstructure was revealed. Transmission electron microscope connected with Ehlers-Danlos Syndrome (EDS) was used to reveal the morphology of second phase particles. Both samples for a high resolution power Transmission Electron Microscopy (TEM) (Jeol JEM 3010) analysis were prepared by using carbon extraction replica method in 5% Nital solution as an etching technique. Both samples were then caught in copper grid of 3mm for using TEM analysis. TEM micrographs clearly revealed the second phase particles in the matrix of steel. The EDS peaks were studied and it was found that the peaks showed the titanium peaks in both the samples A and B and surprisingly there was no any peak found for aluminum. Stoichiometric calculations were carried out and it was found that weight percent nitrogen required for forming TiN is 0.0073, however the total nitrogen present in both the steels A and B is 0.0058 and 0.0061 respectively. That means that all the nitrogen present in the steel matrix was consumed by titanium to form the Titanium Nitride (TiN) so there was no nitrogen remain to fulfil the requirement of aluminum to form the Aluminum Nitride (AlN) particles.

8

Authors: Sardar Jehangir; Sohail Khan; Sulaiman Khan; Shah Nazir,; Anwar Hussain

This paper presents an efficient Optical Character Recognition (OCR) system for offline isolated Pashto characters recognition. Developing an OCR system for handwritten character recognition is a challenging task because of the handwritten characters vary both in shape and in style and most of the time the handwritten characters also vary among the individuals. The identification of the inscribed Pashto letters becomes even palling due to the unavailability of a standard handwritten Pashto characters database. For experimental and simulation purposes a handwritten Pashto characters database is developed by collecting handwritten samples from the students of the university on A4 sized page. These collected samples are then scanned, stemmed and preprocessed to form a medium sized database that encompasses 14784 handwritten Pashto character images (336 distinguishing handwritten samples for each 44 characters in Pashto script). Furthermore, the Zernike moments are considered as a feature extractor tool for the proposed OCR system to extract features of each individual character. Linear Discriminant Analysis (LDA) is followed as a recognition tool for the proposed recognition system based on the calculated features map using Zernike moments. Applicability of the proposed system is tested by validating it with 10-fold cross-validation method and an overall accuracy of 63.71% is obtained for the handwritten Pashto isolated characters using the proposed OCR system.

9

Authors: Irshad Hussain; Faizullah Khan; Ishtiaq Ahmad; Surat Khan; Muhammad Saeed

The energy demand all over the world is increasing rapidly day by day. In traditional power systems, power plants are located far away from the consumer’s premises. This in turn causes a substantial amount of power loss both in transmission and distribution. In general, distribution system has more losses than the losses occurred on the transmission side. It employs that there will be a significant difference between the generated power and the energy consumers that are (physically) far away from the generating stations. Therefore, the electric utilities always remain under stress due to such non negligible amount of losses which has a direct impact on financial management and efficiency of the power system as well. To address this issue different technique have been introduced to reduce line losses and to improve the efficiency. The best among these techniques is line loss reduction through Distributed Generation (DG) which is more effective than the other techniques. In this paper we have taken three 11kV feeders (located at Bannu) as a case study and for the prescribed technique an attempt has been made to increase the efficiency of a system by integrating different capacity of DG into a radial distribution feeder. The results have been analyzed mathematically, however Electrical Transient Analyzer Program (ETAP) simulator is used as a test bed. Finally, the obtained results are presented in tabular and graphical form in terms of clearly defined parameters.

10

Authors: Attiya Baqai; Maria Jan; Rafay Rasheed Maher

Learning through play has always proved its effectiveness in elementary education and has yielded prolific results. Although there are trained instructors, special schools, specific toys and facilities for Visually Impaired (VI), yet the communication between tutors and special children holds a significant gap. Also, tools in market are either too expensive or available in limited quantity in underdeveloped countries. This paper presents a cost effective solution for visually impaired children to play and learn via Braille blocks. These blocks are designed by embossed motives representing numbers, alphabets, shapes and mathematical operators with Infra-Red (IR) tags. The blocks transmit Infrared codes when come in contact with the system. The Braille Blocks System consists of a battery, optical detectors and controller which performs detection and processing of selected IR pattern. This system comprises of three different learning modules namely Words Game, Shapes Game and Math Game. These modules are further divided into several sub-game sections so that the children can learn and improve their communication and academic skills. The presence of audio feedback elevates a child’s capabilities to memorize and concentrate on self-learning and spatial coordination in a fascinating way. The designed system was tested on 20 blind children in “National Special Education Complex” Karachi, Pakistan and an assessment was conducted on basis of different types of errors encountered by children. The suitability of the system was also evaluated by taking feedback from blind students through a questionnaire, proving its effectiveness with 79% of blind children giving either good or very good feedback.

11

Authors: Abdul Majeed Shar, Aftab Ahmad Mahesar, Asad Ali Narejo, Noor Fatima

Pakistan has been suffering from severe energy crisis for decades. Discovering new oil and gas fields plays significant role in alleviating the energy deficit. Exploitation and development of new fields for the country is very challenging due to economic, technological, social and environmental concerns. Hence, it is essential to assess the potential of hydrocarbon bearing formations using integrated analysis techniques in order to explore the resources efficiently. In this paper, we have analyzed Nari sandstone reservoir potential of the country. The key objectives of the study are to characterize petrographic, mineralogical and microstructural data through laboratory study on Oligocene strata of Nari sandstone in the lower Indus Basin. For this purpose, we collected several exposed outcrop samples from different stations in the onshore areas of Nari Sandstone formation. The work performed includes, the integrated study of petrography using Scanning Electron Microscopy (SEM) along with Energy Dispersive Spectrometry (EDS) application. In addition, Quantitative X-Ray Diffraction (QXRD) analysis was performed. The results revealed that these sandstones were mainly composed of quartz grains, which are surrounded by calcite cement. EDS elemental sequence shows Calcium (Ca), Carbon (C), Silicon (Si), Iron (Fe), Magnesium (Mg), Aluminum (AI) and K (Potassium) in variable intensities in the samples indicating the presence of different minerals within these rocks such as quartz, calcite, clay and ferruginous cement. This study is the comprehensive collection of data of Nari sandstones that is essential to assess the potential of hydrocarbon bearing formations.

11

Authors: Faisal Saleem; Ahsan Ali; Inam ul Hasan Shaikh; Muhammad Wasim

This paper investigates the trajectory tracking problem for a Multi-Input Multi-Output (MIMO) Twin Rotor Aerodynamic System (TRAS) using a hybrid architecture based on an H∞ controller and Iterative Learning Control (ILC). TRAS is a fast, nonlinear coupled system and therefore it is a challenging task to design a control system that ensures the tracking for fast changing trajectories. The controllers proposed in the literature for the TRAS through linear approaches tend to have a large control effort, while the ones designed using the nonlinear approaches track only for smooth input trajectories. Both issues are important from control point of view. In this paper, these issues are addressed by designing a feedback H∞ control that stabilizes the system and a feedforward ILC which reduces the control effort. The H∞ controller achieves the tracking for input trajectories with sharp edges, but the control effort required for tracking is large. With the proposed hybrid approach, tracking is achieved by the H∞ controller whereas the required control effort is reduced in each subsequent iteration by ILC. After a few iterations, accurate tracking at a minimized control effort is achieved. The simulations have been performed using MATLAB software and the controller designed through the proposed approach has been validated on nonlinear model of the system. The results of the proposed technique, compared with the flatness-based and back-stepping control strategies, show that the proposed controller ensures accurate tracking at the reduced control effort.

12

Authors: Ghulam Hussain Dars, Mehran Sattar, Muhammad Tauseef, Courtenay Strong, Muhammad Raza Najafi

Water resources managers and policy-makers need reliable projections of hydro-climatic conditions to develop sound water management policies. Global Climate Models (GCMs) are the primary basis for projecting how the climate may change over the coming decades. However, GCMs have low spatial resolution and inherent biases that limit their direct utility for understanding localized climate change impacts. These limitations are particularly pronounced in mountainous areas, where the terrain exhibits variations at scales much finer than the GCM grid spacing. The main goal of this study is to downscale precipitation and mean temperature simulations from an ensemble of 10 GCMs that participated in the Coupled Model Intercomparison Project Phase-5 (CMIP5) under two Representative Concentration Pathways – RCP4.5 and RCP8.5. The simulations were bias corrected using quantile mapping and downscaled to a 30 arc second spatial resolution (approximately 1 km) through using the delta method over the Indus River Basin and Pakistan for 2040-2070. The GCM processing was carried out using the Global Climate Data (GCD) package. The results show that for all seasons and most of the Indus River Basin (IRB) and Pakistan, future precipitation will be highly uncertain except UIB wherein mean annual precipitation is projected to increase by 8% under RCP 4.5 and 14% under RCP 8.5. However, the models are highly confident about increase in the temperature for this region. Relative to the baseline period (1960-1990), the annual mean temperature in the IRB is projected to increase by 2°C under RCP 4.5 and 2.6°C under RCP 8.5 for 2040-2070.

13

Authors: Muhammad Azeem; Junaid Alam Memon; Fateh Muhammad Mari

Environmental and anthropogenic changes in lakes have implications for fishers’ livelihoods in form of their forced migration and occupational change. Those advocating lake restorations often face a dilemma when asked if lake restoration will also restore the lost livelihoods. Answering such questions are difficult because most people are not programmed for frequent changes in their livelihood structures. Using the case study of Manchar Lake fishers who seemingly have faced such transition, this study brings insights on this broad question. We developed an in-person survey based on Contingent Valuation Method (CVM) to study 300 fishers’ responses to a hypothetical situation whereby they were asked to “Switch Back” to Manchar Lake assuming that it has been restored to provide various ecosystem services. Results show that complete transformation in the livelihoods of fishing communities has taken place with remarkable variation in their access to assets and livelihood outcomes. Despite increase in their access to physical capital such as school, hospital, roads, and markets, the communities are still vulnerable to income shocks and rarely enjoy privileges such as house ownership. The comparative state of current and past livelihoods and asset possessions determine ones’ willingness to switch back to fishing in Manchar Lake. Those who may have performed better in the said transition are less likely to return to their erstwhile occupations even if the lake is restored and vice-versa. We conclude that satisfaction with current livelihood outcomes is low and willingness to switch back to fishing in Manchar Lake is high since many had been poor performers in the transition. While the environmental rationale for the Manchar Lake’s ecological restoration already exists, this study suggests that there also exists a socioeconomic rationale albeit in a way that restoration also supports contemporary ecological services such as tourism.

15

Authors: Syed Haseeb Sultan; Arkom Palamanit; Kua-Anan Techato; Muhammad Amin; Khurshid Ahmed Baloch

Bioenergy has gained great interest in the recent years for being environmentally friendly and renewable energy resource. Southern Thailand is well-known for agro-industry including rubber tree plantations and processing, which provide biomass that could be applied to produce bioenergy. Thus, this study aimed to investigate the energy potential of Rubber Wood Chips (RWC), Rubber Wood Pellets (RWP), Unburned Char (UBC) from rubber wood, blended RWC:UBC (50:50%) and blended RWP:UBC (50:50%). The physiochemical properties including bulk density, proximate composition, ultimate composition, heating value, Thermogravimetric Analysis (TGA), and lignocellulose content were determined for the biomass samples. The thermochemical conversion of biomass to syngas was performed using a downdraft gasifier operated at equivalence ratio 0.3. The results showed that the biomass was rich in carbon (content ranging from 44.77 to 58.54%) making it suitable for use as a solid fuel for gasification or combustion. The moisture contents of the biomass samples were below 10%. The contents of volatile matter in RWC and RWP were 74.40 and 75.40%, respectively. The UBC had a high fixed carbon content (50.60%) and comparatively low volatile matter (19%). The bulk densities of RWC, RWP and UBC were 193, 555 and 177 (kg/m3 ), respectively. The TGA showed the maximum weight loss of RWC and RWP around 400 °C, but this was at 800 °C for UBC. The higher heating values of RWC, RWP and UBC were 17.8 MJ/kg, 17.4 MJ/kg and 19.3 MJ/kg, respectively. The RWC and RWP had high cellulose and hemicellulose contents while UBC was rich in lignin. The syngas obtained from any of these biomass samples was mainly CO (10.81-22.67%) and CH4 (0.06-3.16%) with the lower heating value ranging from 2.78 to 4.72 MJ/Nm3 . These results indicate that rubber wood biomass in various forms has relatively high potential for bioenergy applications via gasification, and it can help to support the renewable energy sector in Thailand.

15

Authors: Abid Imtiaz; Adnan Tariq; Ajaz Bashir Janjua; Fahad Sarfraz; Amar ul Hassan Khawaja

Friction Stir Welding (FSW) is a solid-state joining process for metals, non-metals and polymers. It is carried out with the help of a specially designed, non-consumable tool. The heat required, for creating a softened region at the faying surfaces, is generated by rotation of tool against the work piece material. Being a solid-state welding process, it offers several advantages like inducing minimum effect on the mechanical properties of base material, reduced shrinkage and distortion, no spatter or Ultra Violet (UV) radiations etc. However, developing a sound weld requires an appropriate combination of several process parameters e.g. the design of tool, its rotational and traversing speeds etc. To substantiate this aspect, an approach based on Response Surface Methodology (RSM) is presented during this paper that optimizes the combination of process parameters while investigating their effect on the mechanical properties of a friction stir welded butt joint configuration of Polycarbonate. To minimize the total number of combinations a Central Composite Rotatable Design (CCRD) is used with three factors and two levels. The results have shown that the butt joints fabricated at a traverse speed of 14 mm/min, rotational speed of 1700 RPM and with simple cylindrical conical tool geometry yielded the maximum ultimate tensile strength of 51.299 MPa.

25

Authors: Hasham Khan

The rapid increase in the population and fastest development in the industrial sector has increased the energy demand throughout the world. Frequent outages and load shedding has seriously deteriorated the efficiency of the electrical power distribution system. Under such circumstances, the implementation of Distributed Generation (DG) is increasing. Small hydel generators are considered as the most-clean and economical for generating electrical energy. These are very complex nonlinear generators which usually exhibits low frequency electromechanical oscillations due to insufficient damping caused by severe operating conditions. These DGs are not connected to the utility in many cases because, under varying load, they cannot maintain the frequency to the permissible value. This work presents detailed analysis of operating characteristics and proposes a hybrid frequency control strategy of the small hydel systems. The simulation and testing is performed in MATLAB, the results verified the improved performance with the recommended method. The proposed method conserves half of the power consumption. The control scheme regulates the dump load by connecting and disconnecting it affectively. The application of presented methodology is convenient in the deregulated environment, especially under the severe shortage of energy. The proposed model keeps the frequency of system at desired level. It reduces the noise, thereby improving the response time of the designed controller as compared to conventional controllers. The innovative scheme also provides power for small scale industrial, agricultural and other domestic application of far-off areas where the supply of utility main grid is difficult to provide. The recommended scheme is environmental friendly and easy to implement wherever small hydel resources are available.