Archives-February 2012

This paper presents an experimental investigation on the influence of cutting parameters of wire cut Electrical Discharge Machining (Wire-EDM) during the machining of Inconel825.Demand for better surface finish has been increasing recently for super alloys. The low rigidity and high material removal rate of Inconel alloys offers a challenging task in obtaining a better surface finish. The analysis of surface characteristics like surface roughness of Inconel-825 is carried out and an excellent machined finish can be obtained by setting the machining parameters at optimum level. Experimentation has been done by using Taguchi’s L18 (21x37) orthogonal array under different conditions of parameters. The response of surface roughness is considered for improving the machining efficiency. Optimal combinations of parameters were obtained by this method. The confirmation experiment shows, the significant improvement in surface finish (1.36µm) was obtained. Multiple linear regression model have been developed relating the process parameters and machining performance indicates the suitability of the proposed model in predicting surface roughness. The regression analysis are used to predict the error between actual and regression values of surface roughness in Wire EDM process. Experimental results demonstrate that the machining model is suitable and the Taguchi’s method satisfies the practical requirements.

A site earmarked for radioactive waste disposal facility was subjected to geophysical assessment and characterization. The principal aim was to ascertain the ‘competence’ or otherwise of the site and to determine whether or not the geological setting is stable enough to contain the waste. The investigation employed two geophysical techniques; electrical resistivity and seismic refraction surveys. The resistivity profiling survey have shown some zones of low resistivities at specific stations on all four survey lines which implies discontinuities in the rock formation suggesting the presence of geological contact. The seismic surveys have also revealed weak zones at same and close to the stations of the resistivity surveys. These weak zones suspected to be as a result of faults or fractures have been mapped. With the aid of the resistivity sounding data and that of the seismic refraction, the site was thus characterized as a four layer formation with geological contacts at certain points.

Gender differences played an important role in theoretical mechanics to influence students’ learning interests, academic interests and achievements. In order to improve teaching quality and assist students’ learning, we used SPSS to analyze the data of theoretical mechanics test, gained a comprehensive understanding of gender differences on the theoretical mechanics teaching. The findings of the study indicated that the gap of gender difference exists in theoretical mechanics learning. The test showed female students get higher points in theoretical mechanics test. The result of t-test for two groups of male and female students showed that they had significant difference in terms of mean scores obtained in choice questions, calculating questions, particle mechanics and rotating reference frame tests.

The paper explores the herding relationship between spot market and futures market by using two different herding measurements. Heavily traded constituents stocks of Taiwan electronic sector index and finance sector index are used to test the existence of herding. We also examine whether herding behavior has asymmetric reactions for up (bull) markets and down (bear) markets. Daily and 15-minute returns data covering Taiwan spot market and Taiwan futures market are analyzed. The results partly support the information cascade theory and rational asset pricing theory. Investors do herd temporarily but also trade rationally in a long period. Furthermore, daily and 15-minute data demonstrate the investors’ tendency toward herding is higher during market downstream.

On the electrodynamics of moving bodies by Albert Einstein is based on Trickeries (Open letter to Professors, Teachers, Researchers and Students of Physics)

Interspecific and intergeneric hybridization studies were carried out in H.longifilis, C. gariepinus and C.anguillaris under controlled hatchery conditions to estimate their aquaculture potential in terms of fertilizability, hatchability and survival. Fertilization rate in all the nine genetic crosses ranges from 60-87.5%, the fertilization rates of the parentals being significantly higher (P<0.05) with highest value of 87.5% obtained in C.gariepinus. The intergeneric hybrids had the lowest rate of fertilization. Hatchability ranges between 75- 88.1% ,with the parental C.anguillaris being slightly significantly higher than the other genetic combinations. C .a x H. l had the lowest hatchability and their was no significant difference (P<0.05) in percent hatching among the interspecific hybrids. The survival rate in all the nine genetic crosses from hatching up to the end of the two weeks indoor rearing period ranges between 78-89%, which wasn’t significantly different among the interspecific and intergeneric hybrids. C. anguillaris and C. gariepinus had the highest percent survival which was significantly different from all the other mating combinations. The intergeneric hybrid had significantly greater (P<0.05) larval length in comparison to the interspecific hybrids. H .longifilis and the hybrids produced from its eggs had significantly greater body weight than that of C. gariepinus and C. anguillaris.

The crystal structure of the new inorganic-organic hybrid compound [4-OCH3C6H4CH2NH3]2[CdCl4] has been determined by single crystal X-ray diffraction The compound crystallizes in the triclinic space group P with lattice parameters a = 19.007(2), b = 7.3410(8), c = 7.4451(8) Å, , ? =97.222(1)°, V = 1030.59(19) Å3, and Z = 2. The framework of the title compound is built upon layers parallel to (100) made up from corner-sharing [CdCl6] octahedra. 4-methoxybenzylammonium cations are situated between the layers and connect them via an N-H…Cl hydrogen-bonding network. The Cd atom is located on an inversion centre and the coordination environment is described as distorted octahedra. Solid state 13C CP-MAS NMR spectroscopy is in agreement with the X – ray structure. DFT calculations allow the attribution of the carbon peaks to the independent crystallographic sites. Thermal analysis and Infrared spectroscopy were also used to characterize the complex.

Light sequencer is a phenomenon which has been with us since the end of Second World War. Even though it has undergone very robust modification from the mirror balls into pure electronics. The 8051 microcontroller based light sequencer incorporates the programmable capability of the 8051 microcontroller in light sequencing light. This therefore has the advantage of changing the display of lights required as opposed to changing the whole electronics of the system of non-8051 microcontroller based light sequencer for the same effects lighting.

This paper is concerned with the existence of solutions for some partial functional integrodifferential equations with state-dependent delay in Banachspaces. The results are obtained by using Leray-Schauder’s alternative fixed point theorem. Finally, an example is provided to illustrate the main results.

Discovering the methods of constructing the domes, identification of different types of dome, studying the function of the structure, the strategies of drawing them, administrative works, as well as their related issues have been of special interest and concern of Iranian architects. Many valuable books, articles, and reports have been written in this field by Iranian architects. Thus, various types of dome such as rok, nar, and double-shelled have been introduced to the world and their functions have been investigated. In this architecture, ourchin dome, which is of typical characteristics of the tombs in southern part of Iran, has been neglected. Little information about this type of dome is available in the history of Iranian architecture. And this little information is limited to some reports and pictures from foreign tourists and unknown writers, including no more than a few names and dates of constructing of such structures. Therefore, the origin and the reason for the development of such domes as well as their role are still mysterious. The methodology of the current study is descriptive and analytical. In different parts of the present study, comparative, retrospective, and fieldwork studies have been used, whenever needed. In the current research, the root of the word, ourchin dome, and its meaning are pointed out. Also, the origin of Iranian architecture, which dates back to Seljuqid period, is introduced. Then, the geometric relationships of its sides are examined and different varieties of this dome [star and polygonal] are drawn. Studying the typology of the examples of this dome in Iran and Iraq revealed some remarkable points about the geometric, height, and shape of the dome, in addition to the number of its stories. Some factors, like the function of the crown, method of its construction, cover of the dome, and the system of the distribution of the load are clarified. Finally, by investigating the influential cultural and historical factors, we concluded that that the main reason for the development of the general structure of this type of dome was symbolic, not simply religious. This dome by its own or in combination with religious places has played an affective and functional role over time.