International Journal of Research in Science & Technology

5

Authors: Sk. Khadar Basha and Sk. Abdul Rehman

The objective of this project is to generate the radiation pattern of linear arrays like broad side array and end fire array by reducing the side lobes. This project is implemented by using MATLAB. For some applications, single element antennas are unable to meet the gain or radiation pattern requirements so combining several single antenna elements in an array can be a possible solution. Array is a system of similar antennas oriented similarly to get greater directivity in a desire direction. Various techniques can be used to reduce the side lobes in the radiation pattern. Here, we employ windowing techniques for the reduction of side lobes. The 4-term Blackman-Harris window function is a good general purpose window, having side lobe rejection in the high 90s dB and having a moderately wide main lobe. The Kaiser-Bessel window function has a variable parameter, beta, which trades off side lobes for main lobe. It compares roughly to the Blackman-Harris window functions, but for the same main lobe width, the near side lobes tend to be higher, but the further-outside side lobes are low. Antennas exhibit a specific radiation pattern. Tapering of side lobes in the radiation pattern has several advantages and applications. These have wide importance in specific military applications. Military antennas are designed to have a narrow main beam as reasonable to give higher resolution and the lowest side lobes possible to reject echoes and jamming at other elevation angles. Radar was first developed for military purposes. The early surveillance radars often used a line feed and a cylindrical reflector. The radiation pattern from the line feed was shaped to provide lower side lobes and a slightly broader main beam with slightly less gain.

6

Authors: B.O. Afolabi, T.A. Adegbulugbe and A.O.D. Adejumo

The work investigated the effect of electrodes on consumption rate and mechanical behavior of welded mild-steel and galvanized-steel joints, to ascertain their performance level under service conditions, which has increased joint failure and increased equipment cost of maintenance. 20 welded mild-steel and galvanized-steel flat bars (¾” x ¼ “) produced from shielded manual metal arc welding (SMMAW) were prepared using mild steel electrodes, gauge 12 of four selected different brands from local hardware market. Standard methods were applied for tensile properties using Ultimate tensile test machine. Also, the consumption rate of each brand of electrode in joining specified metal types were ascertained through 5 replications within specified time frame (6 seconds) for each metal type. Results obtained from tensile tests in respect to allowable maximum load, breaking point and yield point. The result showed allowable maximum load at tensile strength of 5524.767 N and 5131.088N attained for mild steel welded with Zika electrode and galvanized steel welded with Oerlikon electrode respectively. Changes were noticed in the modulus of elasticity at yield point for galvanized steel welded with Fed electrode, and mild steel welded with China electrode. The consumption rate with equivalent price value was projected to 8 working hours, this gave maximum consumption rate of 528.4 sticks of electrodes (2.11 packs), corresponded to price value of 4,227naira in respect to galvanized steel welded with Zika. It was therefore recommended that Zika electrode brand are in no-way fit to be used on galvanized steel based on tensile properties test and consumption rate. Zika electrode brand is most suitable for mild steel joints for tensile properties, while Oerlikon electrode brand is best suited for galvanized steel joints when the same property is desired. All specified electrode brands are found to be more cost effective when used on mild steel compared to galvanized steel.

7

Authors: Palaparthi.Jagadeesh Chand

The aim of this project is to inform the doctor about the ICU patient condition through wireless. For the medical professionals it becomes important to continuously monitor the conditions of a patient. In a large setup like a hospital or clinical center where a single doctor attends many patients, it becomes difficult to keep informed about the critical conditions developed in each of the patients. This project provides a device which will continuously monitor the vital parameters to be monitored physiological functions of a patient and do data logging continuously. If any critical situation arises in a patient, this unit also raises an alarm and also communicates to the concerned doctor by means of an SMS to the doctor.

10

Authors: Y.N.Raghunath babu

Very recently the use of OFDM in optical systems has attracted increasing interest. Data rates in optical fiber systems are typically much higher than in RF wireless systems.The impairments caused by timing jitter are a significant limiting factor in the performance of very high data rate OFDM systems. In this letter we show that oversampling can reduce the noise caused by timing jitter. Both fractional oversampling achieved by leaving some band-edge OFDMsubcarriers unused and integral oversampling are considered. The theoretical results are compared with simulation results for the case of white timing jitter showing very close agreement. Oversampling results in a 3 dB reduction in jitter noise power for every doubling of the sampling rate.OFDM is a multicarrier modulation scheme that provides strong robustness against intersymbol interference (ISI) by dividing the broadband channel into many narrowband sub- channels in such a way that attenuation across each sub channel stays flat. Orthogonalization of sub channels is performed with low complexity by using the fast Fourier transform (FFT).