Mehran University Research Journal of Engineering and Technology

8

Authors: Farooq S., Yousufani S.A.

Fabric Porosity is an important property in determining the functional properties of a fabric. It relates to the count of a yarn as well as to the type of weave. Twill and satin cotton woven fabrics in three different weft densities (warp density kept constant) were used to investigate the effect of porosity on the dyeuptake within one weave. The effects of change in weave type, keeping yarn densities the same, on the porosity were also investigated. Objective determination of porosity was carried out using an image analysis technique while, colour yield was determined using K/S values. Higher the weft density in a satin fabric low will be the porosity of that fabric. Porosity values varied from 6.85-10.98% for S1 and S3 respectively. However, for the twill fabric no substantial change in porosity have been observed as the porosity values varied from 6.4-5.3% for T1 and T3 respectively. Colour strengths for S1 and T1 are lower than S3 and T3 respectively for all the primary colours at 0.25, 1.00 and 2.00% depth levels. It is observed that the change in colour strength is more prominent at 2% depth level as compared to 0.25% depth level

8

Authors: Unar I.N., Aftab A.,Abro M.

Pakistan is a gas rich but power poor country. It consumes approximately 1, 559 Billion cubic feet of natural gas annually. Gas is transported around the country in a system of pressurized transmission pipelines under a pressure range of 600-1000 psig exclusively operated by two state owned companies i.e. SNGPL (Sui Northern Gas Pipelines Limited) and SSGCL (Sui Southern Gas Company Limited). The gas is distributed by reducing from the transmission pressure into distribution pressure up to maximum level of 150 psig at the city gate stations normally called SMS (Sales Metering Station). As a normal practice gas pressure reduction at those SMSs is accomplished in pressure regulators (PCVs or in throttle valves) where isenthalpic expansion takes place without producing any energy. Pressure potential of natural gas is an untapped energy resource which is currently wasted by its throttling. This pressure reduction at SMS (pressure drop through SMS) may also be achieved by expansion of natural gas in TE, which converts its pressure into the mechanical energy, which can be transmitted any loading device for example electric generator. The aim of present paper is to explore the expected power production potential of various Sales Metering Stations of SSGCL company in Pakistan. The model of sales metering station was developed in a standard flow sheeting software Aspen HYSYS®7.1 to calculate power and study other parameters when an expansion turbine is used instead of throttling valves. It was observed from the simulation results that a significant power (more than 140 KW) can be produced at pressure reducing stations of SSGC network with gas flows more than 2.2 MMSCFD and pressure ration more than 1.3.

10

Authors: Aijaz H., Asad M., Khawaja B.A.

The use of composite laminates is increasing in these days due to higher strength and low density values in comparison of metals. Delamination is a major source of failure in composite laminates. Damage mechanics based theories are employed to simulate the delamination phenomena between composite laminates. These damage models are inherently local and can cause the concentration of stresses around the crack tip. In the present study integral type non-local damage formulation is proposed to avoid the localization problem associated to damage formulation. A comprehensive study is carried out for the selection of different non-local variables. Finite Element simulations based on proposed non-local damage models and classical local damage model are performed and results are compared with available experimental data for UD IMS/924 Carbon/fiber epoxy composite laminate

10

Authors: Katyara S., Hashmani A.A., Chowdhry B.S.

In this paper analysis and mitigation methods of capacitor bank switching transients on 132KV Grid station, Qasimabad Hyderabad are simulated through the MATLAB software (Matrix Laboratory). Analysis of transients with and without capacitor bank is made. Mathematical measurements of quantities such as transient voltages and inrush currents for each case are discussed. Reasons for these transients, their impact on utility and customer systems and their mitigation are provided

14

Authors: Aijaz S., Jokhio S.H., Baloch J.A.

Design and implementation of a WSN (Wireless Sensor Network) that can efficiently work for a longer time period must include identification of the deployment environment context and to conform to the behavior of the sensor nodes. The context information when treated with evaluation factor becomes a process of context awareness and the evaluation factor is called the context attribute. In this paper, we consider the context factor of energy. The paper identifies analyses and evaluates efficiency of two when used in a context aware environment. Furthermore, the study also highlights the strengths and weaknesses of sensor SPIN (Sensor Protocol for Information via Negotiation) and LEACH (Low Energy Adaptive Clustering Hierarchy) protocols with respect to the support for WSN with heavy network traffic conditions. The performance has been evaluated in terms of energy efficiency, data packet transmission, network status, data management, reliability, etc.