Volume 3, Issue 8, August 2012

Determination of the Window to Return to the Equilibrium after the Listing Period


Faculty of Science Economics and Management of Tunis, Tunis
Faculty of Science Economics and Management of Tunis, Tunis

Abstract– This work provides an analysis of the equilibrium value after listing, reflecting the window to return to equilibrium. Our study examined a sample of 103 French companies during 2005-2008. The results show that the underperformance is confirmed in the three years following the IPO. The results allow us to see that investor demand is a good indicator of the timing necessary to return to the equilibrium value after listing. On average, the speed of adjustment of prices after listing is between 20 and 30 trading days (approximately three weeks of negotiations). Thus, the negative and significant relationship between the oversubscription rate and the performance during the three years following the listing can be attributed to over optimism or pessimism of investors from the prospects of the IPO firm.

Keywords— Intrinsic Value, Timing, Oversubscription Rate and Long Term IPO Performance

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Implementation and Analysis of Convolutional Codes Using MATLAB

Nabeel Arshad and Abdul Basit

Department of Electrical Engineering, Institute of Space Technology, Islamabad-Pakistan

Abstract– Maintenance of the quality of data is the most important thing in communication. There are various factors that affect the quality of data when it is transferred over a communication channel like noise, fading etc. To overcome these effects channel coding schemes are introduced. In this paper one type of channel coding is described namely Convolutional Codes. Algorithms used for encoding of data are NSC (Non-systematic Convolutional Codes) and for decoding part Viterbi algorithm is used. Their performance is analyzed in terms of BER for different parameters such as code rate, coded and un-coded data. Furthermore, performance of convolutional codes is analyzed when a binary image is transmitted over the channel. All the simulations are conducted in MATLAB over AWGN channel using BPSK modulation scheme.

Keywords— Channel Coding, Convolutional Codes, Non-Systematic Convolutional Codes, Viterbi Algorithm, MATLAB, AWGN, BPSK

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The Use of Ugwuoba Clay as an Adsorbent for Zinc (II) Ions from Solution

F. A. Dawodu, G. K. Akpomie, M. E. Ejikeme and P. C. N. Ejikeme

Department of Chemistry (Industrial), University of Ibadan, Ibadan, Oyo State, Nigeria
Projects Development Institute (PRODA), Emene Industrial Layout, Emene, Enugu, Nigeria
Department of Chemical Engineering, Enugu State University of Technology (ESUT), Enugu, Nigeria

Abstract– The adsorption potential of Ugwuoba clay (Nigeria) for the removal of Zinc (II) ions from aqueous solution was studied. The aim of this experiment was the use of Ugwuoba clay as a cheap alternative adsorbent for Zinc (II) ions in order to assist small scale industries and developing Nations overcome the problems of high cost involved in treating effluents. Batch adsorption technique was used to investigate the effect of initial metal ion concentration, pH, contact time, Sorbent dose and temperature on the adsorption process. Chemical analysis of the clay showed SiO2 and Al2O3 as the major constituents. FTIR analysis revealed some functional groups which could influence the adsorption process. The study on pH revealed the adsorption to be pH dependent as optimum pH was achieved at pH 6.0.Effect of contact time showed a fast initial uptake within 20 minute with equilibrium established before 60 minutes. Temperature experiment indicated an increase in adsorption with increase in temperature. An increase in uptake capacity and a decrease in percentage removal with increase in zinc (II) ion concentration was observed. Similarly, two opposite trend were noted in which there was an increase in percentage removal and a decrease in adsorption capacity with increasing sorbent dose. These result indicated that Ugwuoba clay can be used as a cheap and effective adsorbent for the removal of zinc (II) ions from aqueous solution.

Keywords— Adsorbent, Ugwuoba clay, Zinc and Zn (II) Ions

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The Role of Mobile Ad-hoc Networking for Pervasive Computing

Aytizaz Ahmed, Faheem Khan, Rahatullah, Gulrukh Khan and Yasir Ali

Gandahara University Peshawar, Pakistan
Agriculture University KPK Peshawar, Pakistan

Abstract– In the coming future, a pervasive computing Environment can be predictable based on the current advancements in computing and Communication technologies. Next generation of Mobile Communications will consist of both prominent Infrastructures Wireless Networks and novel Infrastructureless Mobile Ad hoc Networks (MANET s). The particular features of MANET get these technology huge opportunities together with rigorous dispute. This paper illustrates the essential issues of Ad hoc Networking by giving its associated Research background consisting of the ideas, features, condition, and applications of MANET. Particular concentration is given to Network layer Routing method of MANET and main Research issues consist of fresh X-cast Routing Algorithms, Security & consistency methods, QoS model, and mechanisms for networking with outside IP Networks. Some of the technical disputes MANET cause are as well presented, based on which the paper show few of the main Research issues for future work in Ad hoc Networking technology.

Keywords— Mobile Communications, Wireless Networks, Ad hoc Networking, Pervasive Computing and Routing Algorithm

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Presentation a New Method Based on Using Emotional Intelligent Controllers for Wind Turbine Active and Reactive Power Equipped With DFIG

R. Sedaghati and M. Hayatdavudi

Department of Electrical Engineering, Beyza Branch, Islamic Azad University, Beyza, Iran

Abstract– Regarding to the serious challenges facing widespread use of wind turbines (Part of which should rest in the design phase and the other in control phase and by developing effective controlling strategies) and also lack of proper efficiency of various strategies of classic control, the appeal of the intelligent tools and ideas especially with regard to benefits seem invaluable. In this paper, in order to control the active and reactive power of wind turbine equipped with DFIG, an appropriate control strategy (in the form of vector control) has been provided and to implement this control strategy, the new intelligent controllers designed based on the mechanism of human brain emotional learning have been used. According to simulation results, the proposed control system has had a good performance in terms of response rate, response ripple and persistent error and also enjoys significant consistency against any changes in wind speed and parameters of the system.

Keywords— Active and Reactive Power, Double Fed Induction Generator (DFIG), Emotional Learning, Wind Turbine and Intelligent Controller

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Evaluation of GPS in Orthometric Heights Determination in Khartoum State (Sudan)

Dr. Nagi Zomrawi Mohammed, Dr. Abd Elrahim Elgizouli Mohammed and Engineer Osman Bakry

Sudan University of Science and Technology, Sudan
Karary University, Sudan

Abstract– Levelling is the usual technique used to determine difference in height between ground points. Now a days Global Positioning system (GPS) provides a quick modern technology to determine this difference. Because the datum surfaces are different in both techniques, different results may be expected. In this research work, difference in heights between numbers of points, in Khartoum State, were carried out using both ordinary levelling (in which Geoid is the reference datum) and GPS techniques (in which Ellipsoid is the reference datum). Results obtained showed that GPS data can be used directly to produce contour map up to 1:100,000 map scale with 25m interval. Results also assisted to determine the Geoid undulation in the area. Moreover, GPS data can be improved using EGM2008 Gravitational model, to be suitable for 1:25,000 contour map scales, with 6.25m contour interval.

Keywords— GPS, Ordinary and Geodetic Levelling Orthometric Height and Geoid Undulation

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