Numerical Method in Two Dimensional Boundary Layer Theory for Incompressible Viscous Fluid

In this paper laminar flow of incompressible viscous fluid has been considered. Here two numerical methods for solving boundary layer equation have been discussed; (i) Keller Box scheme, (ii) Shooting Method. In Shooting Method, the boundary value problem has been converted into an equivalent initial value problem. Finally the Runge-Kutta method is used to solve the initial value problem. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16549 Rajshahi University J. of Sci. 38, 61-73 (2010)

Characterizations of m-Normal Nearlattices in terms of Principal n-Ideals

A convex subnearlattice of a nearlattice S containing a fixed element n?S is called an n-ideal. The n-ideal generated by a single element is called a principal n-ideal. The set of finitely generated principal n-ideals is denoted by Pn(S), which is a nearlattice. A distributive nearlattice S with 0 is called m-normal if its every prime ideal contains at most m number of minimal prime ideals. In this paper, we include several characterizations of those Pn(S) which form m-normal nearlattices. We also show that Pn(S) is m-normal if and only if for any m+1 distinct minimal prime n-ideals Po,P1, ., Pm of S, Po ? ? Pm = S. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16548 Rajshahi University J. of Sci. 38, 49-59 (2010)

Characterizations of relative n-annihilators of nearlattices

In this paper we have introduced the notion of relative n-annihilators around a fixed element n of a nearlattice S which is used to generalize several results on relatively nearlattices. We have also given some characterizations of distributive and modular nearlattices in terms of relative n- annihilators. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16545 Rajshahi University J. of Sci. 38, 17-24 (2010)

Stability of Radial Flow Subjected to a Radial Magnetic Field

The linear stability of radial flow of a viscous fluid in the presence of a radial magnetic field is investigated. Basic velocity field q0 = (c/r,0,W) and magnetic field B0= (A/r,0,0) are considered in an annulus between two concentric cylinders. To analyze hydro-magnetic stability, inner product method is employed. The stability condition derived is found to remain valid even when the local velocity is not entirely radial, and that the magnetic field exerts a stabilizing effect on the flow. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16547 Rajshahi University J. of Sci. 38, 41-48 (2010)

Anodisation of Aluminium in Aqueous Sodium Oxalate and Sodium Sulphate Media

An investigation was conducted on the anodisation of commercial grade aluminium in aqueous sodium sulphate and sodium oxalate solutions. The parameters investigated were anodisation potential and electrolyte composition. Degree of anodisation was evaluated by visual observation of the anodised surface, analyses of current-concentration graphs at constant potential and current-potential characteristics, and measurement of corrosion rate of the anodised surface. Anodisation potential played an important role on the degree of anodisation. The optimum potential was 400 mV and 800 mV wrt saturated Ag/AgCl (SSE) reference electrode for sodium sulphate and sodium oxalate solutions respectively. Below and above the optimum potential poor anodisation was due to insufficient production of Al3+ to form anodic film and surface breakdown respectively. Anodisation increased with the increase of oxalate concentration. Sulphate concentration was less effective on the degree of anodisation. Between the two electrolytes sodium oxalate was more suitable than sodium sulphate for aluminium anodisation. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16544 Rajshahi University J. of Sci. 38, 09-16 (2010)

Desire for a Child in Rural Area of Bangladesh: A Logistic Regression Analysis

The main focus of this study is to draw attention to some demographic, socio-cultural and economic, and programmatic factors, which are affecting the desire for a child in rural area of Bangladesh. The study shows that about 40% of the rural women aged 10-49 years desired for a child. Applying logistic regression model with R2 and correct classification rate for checking the quality of fit on Bangladesh Demographic and health Survey (BDHS) 2004 data, the findings indicate that for achieving the replacement level fertility, the family planning program should be strengthened among the ever-married women under age 30 years. The probability of desire for an additional child is significantly higher in Chittagong and Sylhet divisions. It has also been clearly observed that desire for a child is higher among women having age at marriage 18+ years and also among women having higher education. Women having access to mass media especially TV have a statistically lower probability in desiring for a child than those without access. The probability of desire for an additional child is significantly lower for women who are involved to NGOs than that of the women who are not involved. Finally, the paper provides some suggestive policy measures so that the planners and implementers may take appropriate initiatives for achieving the replacement level fertility in Bangladesh. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16550 Rajshahi University J. of Sci. 38, 75-86 (2010)

Adolescence Aggression as Related to Gender and Birth Order

In the present study an attempt was made to find out whether aggressive behaviour is related to gender and birth order of the adolescence. A Bengali version of the aggression scale of Edwards Personal Preference Schedule (EPPS) was administered to one hundred students from different colleges in Rajshahi city. In order to investigate the relationship between aggressive behaviour and gender, they were divided into two groups, male and female and comparisons were made between them, on the basis of the scores obtained on the aggression scale employing‘t’ test. Secondly, in order to study the relationship between aggressive behaviour and birth order, the respondents were divided into two groups- first born and last born and comparisons were made between the two groups. The results of the study suggest that males are more aggressive than females and the last born children are more aggressive than the first born children. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16552 Rajshahi University J. of Sci. 38, 97-107 (2010)

UV Emission from N2/O2 Pulse Microwave Plasma

The emission spectrum from pulse microwave discharge of N2/O2 gas mixture in the UV range (from 200 – 400 nm) was studied in a cylindrical quartz tube aiming to apply it as a mercury free UV light source. The UV light in the 200-280 nm range has germicidal effect which can be used for water purification. In our previous work we used continuous microwave power to produce UV emission from N2/O2 discharge. In the present work we used pulse microwave power instead of continuous microwave power. We studied the dependence of pulse width and pulse interval on the intensity of the UV emission from N2/O2 discharge. Experimental results showed that the UV emission intensity emitted from N2/O2 gas discharge in 200- 400 nm region does not vary with pulse width and pulse interval but depends on applied average power. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16543 Rajshahi University J. of Sci. 38, 01-08 (2010)

Post-Irradiation Ageing Effect on Cytological Characters of Crotalaria Saltiana

Post-irradiation ageing effect on different cytological characters of Crotalaria saltiana were studied. Mitotic index followed no decreasing or increasing tendency based on the doses of gamma rays. Interphase chromosome volume was not found to increase with an increase of gamma rays. Percentage of pollen sterility was found to be lower in the lower doses and higher in the higher doses. Irregularities such as, formation of fragments, bridges, laggards, single and multiple chromatid bridges, unequal distribution and abnormal nuclear arrangement were recorded. This study reflects that irradiated seeds of Crotalaria saltiana showed no such dose wise effect and that might be due to ageing effect for long time. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16551 Rajshahi University J. of Sci. 38, 87-95 (2010)

Linear Stability of a Thin Film Flowing Down an Uneven Incline

The linear stability of a thin film of viscous fluid falling down an uneven inclined heated wall is examined. Long wave theory developed by Benny [1] is employed. It is demonstrated that Marangoni effect makes the flow unstable when either the inclination is quite steep or when the bottom undulations are sufficiently short. DOI: http://dx.doi.org/10.3329/rujs.v38i0.16546 Rajshahi University J. of Sci. 38, 25-39 (2010)