Mehran University Research Journal of Engineering and Technology

6

Authors: Tariq Jamil Saifullah Khanzada, Sheeraz Memon, Naveed Ahmed Jaffari

The OFDM (Orthogonal Frequency Division Multiplexing) is well-known, most utilized wideband communication technique of the current era. SCT (Single Carrier Transmission) provides equivalent performance in time domain while decision equalizer is implemented in frequency domain. SCT annihilates the ICT (Inter Carrier Interference) and the PAPR (Peak to Average Power Ratio) which is inherent to OFDM and degrades its performance in time varying channels. An efficient channel model is presented in this contribution, to implement OFDM and SCT in time domain using impulse responses. Both OFDM and SCT models are derived dialectically to model the channel impulse responses. Our model enhances the performance of time domain SCT compared with OFDM and subsides the PAPR and ICI problems of OFDM. SCT is implemented at symbol level contained in blocks. Simulation results implementing Digital Radio Monadiale (DRM) assert the performance gain of SCT over OFDM.

8

Authors: Imdad Ali Ismaili, Zeeshan Bhatti, Azhar Ali Shah

Dictionaries are essence of any language providing vital linguistic recourse for the language learners, researchers and scholars. This paper focuses on the methodology and techniques used in developing software architecture for a UBSESD (Unicode Based Sindhi to English and English to Sindhi Dictionary). The proposed system provides an accurate solution for construction and representation of Unicode based Sindhi characters in a dictionary implementing Hash Structure algorithm and a custom java Object as its internal data structure saved in a file. The System provides facilities for Insertion, Deletion and Editing of new records of Sindhi. Through this framework any type of Sindhi to English and English to Sindhi Dictionary (belonging to different domains of knowledge, e.g. engineering, medicine, computer, biology etc.) could be developed easily with accurate representation of Unicode Characters in font independent manner.

8

Authors: Shaheen Aziz, Suhail Ahmed Soomro, Ghulam Yasin Shaikh

The FBC (Fluidized Bed Combustion) is a technique used to make solid particles behave like fluid and grow very fast for the power generation using low grade coal. Due to its merits, first time this technology has been introduced in Pakistan by installing 3x50 MW power plants at Khanote. Fluidized beds have long been used for the combustion of low-quality, difficult fuels and have become a rapidly developing technology for the clean burning of coal. The FBC Power Plant at Khanote has been facing operational and technical problems, resulting frequently shut down of generation units, consequently facing heavy financial losses. This study reveals that due to the presence of high percentage of silica in the lime stone that are further distributed in the bottom ash, fly ash and re-injection material, the generation tubes in the boiler and wings/blades of ID (Induced Draft) fans were eroded. In addition, filter bags were also ruptured; resulting frequent shut down of power plant units.

12

Authors: Muhammad Arshad , Mohammad Ahmad Choudhry

In this paper we have presented a novel technique for the navigation and path formulation of wheeled mobile robot. In a given environment having obstacles, a path is generated from the given initial and final position of the robot. Based on the global knowledge of the environment a global path is formulated initially. This global path considers all the known obstacles in the environment and must avoid collision with these obstacles, i.e. the formulated path must be safe (collision free). For global path formulation strategic schemes have been employed using the a priori knowledge of the environment. The global path is fed to the robot. When unknown obstacles come in the path of the robot, it must deviate from the given global path and should generate a local path to avoid collision with the new unknown obstacle. By using sensors data the reactive schemes have been implemented for local path formulation. For local path formulation the path has been subdivided into intermediate steps known as sub goals. In the existing approaches known and unknown objects are considered separately. But in some of the practical applications known and unknown objects need to be considered simultaneously. This paper considers the problem of robot motion formulation in an environment having already known obstacles and unknown new moving objects. A Novel algorithm has been developed which incorporates local path planner, optimization and navigation modules. As unknown objects can appear in the environment randomly therefore uncertainty in the environment has been considered.

16

Authors: Liaquat Ali Khan, Muhammad Shahid Khalil, Fathi Mahfouz

Energy efficient systems are the most desirable systems. Due to huge rise in energy prices and lack of availability of energy, the effective use of energy has become the need of time. Energy recovery both in heating systems as well as in air-conditioning systems saves a lot of energy. In this paper energy recovery system has been designed and optimized for central air-conditioning systems for various ranges. Cost function includes capital cost along with pumping and exergy destruction cost. This shows that installation of energy recovery system with a central air-conditioning has a significant amount of saved energy and payback period is within a year. PFHE (Plate Fin Heat Exchanger) is designed and optimized using evolutionary optimization. In order to verify the capabilities of the proposed method, a case study is also presented showing that significant amount of energy is recovered at a reasonable payback period. Sensitivity analysis is also done with the energy prices.