iosr-JMCE   Volume-1 ~ Issue-1

ABSTRACT: With the growing trend of population Pakistan is gradually enlisting in the top ten countries with the major share of its city Karachi and financial hub of Pakistan. It is becoming the largest city of Asia. From the past decades, Unemployment, Illiteracy, lack of medical facilities are the highlighted problems of Pakistan and normally people prefer to migrate Karachi as per the fulfillment of their needs and requirements. As per the statistics, from the migrated people, 15% to 20% are associated with the construction and labor works. They pretend to do work in the open construction sites due to high level of illiteracy having a language, cultural and social behavior in city. The whole family is entirely based on that particular labor and they are willing to do extra work in order to get extra beneficial money. In some cases, children of the labors also engaged with that work on daily wages. Due to high impact of cultural behavior, the labors have a little knowledge of construction safety and this ultimately correspond to the onsite accidents. The thematic idea is purely based with the formulation of policy for the life saving of mankind with respect to construction industry. Various types of labors are interviewed accordingly in order to get the clear picture of site accidents with the respective measure which is the ultimate goal of this research paper.
Keywords: - Accidents, Construction, Karachi, Labors, Safety Policy

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Abstract : Orthogonal frequency division multiplexing (OFDM) is a special case of multicarrier transmission where a single DataStream is transmitted over a number of lower rate subcarriers. In July 1998, the IEEE standardization group decided to select OFDM as the basis for their new 5-GHz standard aiming a range of data stream from 6 up to 54 Mbps. This new standard is the first one to use OFDM in packet-based communications. In wireless communication, concept of parallel transmission of symbols is used to achieve high throughput and better transmission quality. Orthogonal Frequency Division Multiplexing (OFDM) is one of the techniques for parallel transmission. The idea of OFDM is to split the total transmission bandwidth into a number of orthogonal subcarriers in order to transmit the symbols using these subcarriers in parallel. In this paper we will discuss the basics of OFDM techniques , role of OFDM in this era, its benefits and losses and also some of its application.
Keywords: - Orthogonal Frequency Division Multiplexing(OFDM) ,BER , ISI, PAPR , DVB, DAB

[1] G. Hill, M. Faulkner, and J. Singh, "Reducing the peak-to-average power ratio in OFDM by cyclically shifting partial transmit sequences," Electronics Letters, vol. 36, pp. 560-561, Mar 16 2000.
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[6] Understanding an OFDM transmission: http://www.dsplog.com/2008/02/03/understanding-an-ofdm-transmission/
[7] Minimum frequency spacing for having orthogonal sinusoidals http://www.dsplog.com/2007/12/31/minimum-frequencyspacing- for-having-orthogonal-sinusoidal
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Abstract -- Fibre composites are being used in various applications from aerospace, military, marine boats and submarine to renewable energy generation. Higher energy demands across the developed and growing world for the usage and replacement of conventional materials with polymer composite materials for engineering applications which is always questioned by the end user, unless the research oriented reliable supporting certification is made available. The reinforcement materials are highly hygroscopic, the matrix material provides protection to the reinforcement. Since the edges of parts made of composite materials are exposed to environment, water molecules travels along the reinforcement and cause damage to the interfacial bonding, further the performance of the composite laminate gets effected. In this scenario, the investigation related to this aspect requires quantitative assessment which is carried out with accelerated simulation of the real time situation to provide a scope to characterization of Glass fibre reinforced polymer composite (GFRP) laminates subjected to variable water conditions. This investigation is to study the combined effect of related parameters, moisture salt and temperature. The test results reveal that strength degradation by moisture absorption and temperature effect over the lifecycle of GFRP composite exposed to water and temperature for a long period.
Keywords: Glass fibre reinforced polymer composite (GFRP), Resin transfer moulding (RTM), Hygrothermal ageing, retention ratio, flexural modulus.

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Abstract: This work is aimed at the active vibration control of a flexible structures using piezoelectric material. A simple supported plate structure, which is supported at two opposite ends, is taken as the flexible structure with piezoelectric materials as sensors and actuators. Sensors and actuators, which are square in shapes, are embedded to the parent structure. The active controller was designed to control first three modes of vibration of plate. First, the analysis for the transient vibrations in a simple supported plate structure was performed which was followed by the analysis of the same simple supported plate structure when embedded upon with a pair of sensor and actuator. The plate was discretised into several small rectangular elements (6X6, 7X7… 11X11) of identical size in order to assign the different locations to sensors and actuators, which were assumed to be of the exact shape of the discretized plate elements. Further a LQR controller is applied for attenuating the global structural vibration. Settling time for each different location of piezoelectric patch location was observed which was then followed by an interpretation for the optimal location for piezoelectric patch for maximizing the vibration control. The model designed for study was duly verified with the results from past literature and an agreement between the both was observed.
Keywords -Active Vibration Control, Plate, Vibration Control, Smart Structure, LQR, POF

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[10] Narayanan S. and Balamurugan V., 2003, "Finite element modeling of piezolaminated smart structures for active vibration control with distributed sensors and actuators", Journal of Sound and Vibration, 262: 529–562.