# Volume 4, Issue 9, October 2013

## Dual Reciprocity-Boundary Element Method Applied to the Solution of the Equation of Helmholtz

### Jorge Humberto Vargas Aparicio, Helvio Ricardo Mollinedo Ponce de León, Lesli Ortega Arroyo and José Ángel Ortega Herrera

#### Mechanical Engineering, National Polytechnic Institute, Mexico DF Interdisciplinary Professional Unit of Engineering and Advanced Technology, National Polytechnic Institute, Mexico, DF School of Mechanical and Electrical Engineering, professional unit Azcapotzalco National Polytechnic Institute, Mexico DF

Abstract– This paper develops the application of the Dual Reciprocity - Boundary Element Method (DR-BEM) to pose the problem of the Helmholtz equation in acoustics problems. Because one of the main problems in the analysis of acoustic vibrations in internal cavities is to determine the natural frequencies of the acoustic system and its associated vibration modes, in this paper we develop the formulation by the boundary element method (BEM) and two-dimensional geometries modal analysis to compare the results with the finite element method (FEM) modal analysis based on the DR-BEM which is self-developed method provides a good approximation compared with the results obtained by the FEM. The proposed procedure has been programmed using the MATLAB ® program. We have obtained the natural frequencies for a two-dimensional domain, comparing the results obtained using DR-BEM with the Finite Element Method.

Keywords— Helmholtz Equation, Boundary Element Method (BEM), Finite Element Method (FEM) and Dual Reciprocity - Boundary Element Method (DR-BEM)

## Nanofluid Effect on the Flow and Heat Transfer Over an Unsteady Stretching Sheet under Consideration of Radiation

### Mohammad Mehdi Keshtkar and Amin Altaha

#### Department of Mechanical Engineering, Islamic Azad University, Kerman Branch, Iran

Abstract– In this work, the effect of Nanofluid on the heat and ﬂuid ﬂow over an unsteady stretching sheet in presence of thermal radiation is analyzed. The governing nonlinear partial differential equations have been reduced to the coupled nonlinear ordinary differential equations by the similarity transformations. An efficient numerical shooting technique with a fourth-order Runge-Kutta scheme was used to obtain the solution of the boundary value problem. The similarity equations were solved numerically for one typs of nanoparticles, namely copper with water as the base fluid with the Prandtl number Pr = 3.73 to investigate the effect of the solid volume fraction φ and another parameters of the nanofluid. The results of velocity and temperature distributions for different parameters such as the solid volume fraction, the unsteadiness parameter and the radiation parameter were obtained. It is shown that the heat transfer rate is increased with increasing φ. The present results are compared with some reported theoretical results by other investigators and good agreement is found.

## Context Information Retrieval with Organizational Security Provision

### Sumbleen Kanwal, Fiaz Majeed, Naveed-e-Qandeel, Rabia Urooj, Usman Ali, Qamar-un-Nisa and Muhammad Aadil Butt

#### Department of Information Technology, University of Gujrat, Gujrat, Pakistan Department of Computer Science, University of Gujrat, Gujrat, Pakistan

Abstract– Search engines or Information Retrieval (IR) Systems are commonly used for searching on the World Wide Web (WWW). The users provide keyword query which is parsed by the system and matched in the document databases maintained on web servers. In the organizations, the search is completely different in comparison to WWW. Each organization provides restricted access of each document to relevant users. To provide security on confidential documents, those are placed in local systems. Such decentralized approach for security provision creates many problems e.g. decision-making is difficult for higher management. Such decentralized approach is also the cause of misplacement of documents or totally loss of them in case of damage of the target system. In this paper, we propose a centralized approach where all documents are maintained on a central server. It provides similar security as maintained in decentralized approach. Such IR system performs intelligent search against the type of user. A prototype system has been developed to evaluate the proposed approach. Experiments show that this solution has viable benefit for implementation in organizations.

Keywords— Inverted Index File, Views, Database Rights, Organization Security, Search Engine, Natural Language Query and Information Retrieval

## Study of Excessive Cabin Temperatures of the Car Parked in Oman and its Mitigation

### Sudhir Chitrapady Vishweshwara and Jalal Marhoon AL.Dhali

#### Caledonian College of Engineering, Sultanate of Oman

Abstract– High solar global insolation in Oman causes typically very high ambient temperature especially during summer season. During summer if the cars are parked directly under the sun, cabin inside the car will experience a kind of greenhouse effect this will lead to higher cabin temperature and cause problems inside the car like color fading and seat upholstery wear and tear and even cause damage to other cabin elements. The high temperature prevailing inside the vehicle parked under the sunlight is definitely unreceptive to the occupants when they arrive to take a drive. This paper demonstrates a temperature measurements carried out inside a sedan car which was parked under the sunlight to study the temperature pattern inside a parked car. Further investigation was carried out to minimize the temperature rise inside a parked car by developing and installing simple ventilation systems with a set of fans to purge the hot air trapped inside the cabin. A simple ventilation system was developed by means of two fans which drove out the hot trapped air and a secondary fan to cool down the temperature inside the car by providing fresh air for limited time. A solar photovoltaic panel was used to drive the ventilation system which made the ventilation system completely independent from the car power source. The experimental investigation revealed that, on a bright sunny day, the vehicles cabin air temperatures was approximately 220C higher than the ambient temperature, while with the developed ventilation the difference between the cabin and outside air temperature was reduced by 50% approximately.

Keywords— Cabin Air Temperature, Parked Car, Radiation, Solar Photovoltaic and Ventilation

## Crash Probability Occurrence and Stock Market Efficiency the Tunisian Stock Exchange Case via Shannon Entropy

### SAHLI lamia and Adel Boubaker

Abstract– In this study, we evaluate the relationship between efficiency and probability of the crash, thus the evolution of the daily informational efficiency is measured for Tunisian stock market index (TUNINDEX) over the period [1998 – 2008]. The efficiency, which is the issue addressed by the weak-form efficient market hypothesis, is calculated using a new method the Shannon entropy and the symbolic time series analysis. A logit model is applied in order to study the relationship between efficiency and probability of the financial crash.

Keywords— Informational Efficiency, Financial Crashes, The Shannon Entropy and Logit Model

## Systemic Analysis of Iron Extraction from Iron Oxide Ore based on Leaching Temperature and Input Concentration of Acetic Acid

### T. O. Chime and O.D. Onukwuli

#### Department of Chemical Engineering, Enugu State University of Science & Technology, Enugu, Nigeria Department of Chemical Engineering, Nnamdi Azikiwe University, Awka, Anambra Nigeria

Abstract– This paper presents a systemic analysis of iron extraction based on the leaching temperature and input concentration of acetic acid during the leaching process. A model was derived and used as a tool for the analysis. The model is expressed as: α = - 3.9068 lnβ - 1.905 lnθ + 60.89; The validity of the two-factorial natural logarithmic model was found to be rooted on the expression α - 60.89 = - 3.9068 lnβ - 1.905 lnθ where both sides of the expression are correspondingly approximately equal. Statistical analysis of the extracted iron concentration as obtained from derived model and experiment for each value of the leaching temperature and input concentration of acetic acid considered shows standard errors of 0.4238 & 0.1386% and 0.4238 & 0.1386% respectively. Extracted iron concentrations per unit leaching temperature as obtained from derived model and experiment are 0.178 and 0.183 % /0C. Similarly, extracted iron concentrations per unit input concentration of acetic acid are 7.13 and 7.32 % / M. Deviational analysis indicates that the maximum deviation of the model-predicted iron extraction (from experimental results) is less than 1.5%, implying a confidence level above 98%.

Keywords— Analysis, Iron Extraction, Iron Ore, Leaching Temperature and Acetic Acid Concentration

## Key Performance Indicators of Employability of Graduating Engineers from an Engineering College in Oman

### Ilango Sivaraman, Ahmed Al Balushi and D.H. Rao

#### Caledonian College of Engineering Jain College of Engineering

Abstract– Key performance indicators (KPIs) provide parameters for measuring the results of an organization. However, if the performance indicator is qualitative in nature, such as the employability of recent graduates from an engineering college, the task is more complex. This kind of measurement calls for an assessment of the need for such KPIs, the practices of the college and an understanding of the process for implementing the identified KPIs. KPIs are normally numerical measurements that can be linked to a performed task, but the spirit of the task should not be captured only in numbers. This study was done in a college located in Muscat, Oman, where the implementation of KPIs is currently in a nascent state and is initiated and supported by the Ministry of Education. There is a wide range of stakeholders in higher education, including the students, students’ parents, the staff of the college, the management of the college, the government, the employers and even the society in which the college is located. However, this paper considers only the immediate stakeholders - the students, the staff and the college administration - focusing more on the college and its contribution to the employment of its graduating students. The responsibility is perhaps equal for all three stakeholders in their contribution towards graduates’ employability, but as per the KPIs identified, the college administration has more tasks to perform in the process.

Keywords— KPIs, Employability and Graduating Engineers

## Modeling and Statistical Analysis of Ultimate Tensile Strength LDPE/Date Palm Wood Flour Composites

### R. M. Government, O.D. Onukwuli, C.U. Atuanya, C.O. Nkuzinna, I.A. Obiora-Okafo and S.O. Aliozo

#### Nnamdi Azikiwe University, Awka, Anambra state, Nigeria

Abstract– The effect of particle size and filler content on the ultimate tensile strength of Date palm wood flour-recycled low density Polyethylene composites was studied. The Date palm wood flour used as filler for low density Polyethylene at 4, 8, 12 and 30% wt of filler content. The study was carried out at different particle sizes of 150, 212, 250 and 300 µm of the fillers. The particle size of the corresponding filler, ultimate tensile strength was determined. A two-series factorial model which shows that the ultimate tensile strength of Date palm wood flour-Low density polyethylene composites can be predicted by substituting particle size and filler content. This model was formulated using experimental data in this research and with the aid of software C-NIKBRAN DATA analytical memory. The formulated model was validated using deviational and statistical Analysis. Based on the foregoing, it is strongly believed that the proximity of deviation and correlations from experiment and model-predicted results are indicative of the model validity.

Keywords— Modeling, Date Palm, Ultimate Tensile Strength, LDPE and Composite