Annual Research Symposium (ARS)
http://repository.kln.ac.lk/handle/123456789/154
2024-03-29T08:09:46ZProviding access to public health information via the institutional repository, Faculty of Medicine: A feasibility study based on medical undergraduates.
http://repository.kln.ac.lk/handle/123456789/23861
Providing access to public health information via the institutional repository, Faculty of Medicine: A feasibility study based on medical undergraduates.
Abeygunasekera, C.M.; Marasinghe, M.P.L.R.
Community Medicine Clerkship and Community Attachment programs provide opportunity for
medical undergraduates to learn how public health services are provided to the community.
Their knowledge on health promotion, disease prevention, healthcare planning and management,
demography and understanding epidemiology of diseases in the Sri Lankan context are very
important. They are expected to read from diverse information sources to gain this knowledge,
in addition to field based learning. As most of the recommended reading materials are considered
grey literature sources, students are in a difficulty to access those resources within the library.
Students face difficulties in accessing available online materials too, as some of the websites do
not provide the information in a user friendly manner.
With the understanding of possible barriers to access information, the Medical Library,
University of Kelaniya, has developed a repository collection on ‘Public Health Information
Resources,’ which are recommended as student reading materials for Community Medicine
Clerkship and Attachment programs. This is under its online Institutional Repository (IR),
developed using DSpace Software. This repository provides links to access a collection of
resources published by different institutes. This is in addition to university libraries, which
develop online digital repositories to preserve and distribute the intellectual scholarly
information of the parent institute.
A questionnaire and the User Guide to access the repository were given to a sample of fifty (50)
students from Batch 21, who completed the Clerkship programme. Response rate to the
questionnaire was 82% and more than 80% of students who were among the respondents ranked
the collection as a useful resource which fulfilled their public health information needs. Barriers
to information access were also assessed. Respondents have identified a list of difficulties they
had in the past. Based on the feedback received, a resource collection inclusive of students’
suggestions is being planned to be introduced to the next batch of students.
2013-01-01T00:00:00ZAn Assessment of the Influence of Fundamental Factors on Share Prices in Sri Lanka,
http://repository.kln.ac.lk/handle/123456789/17297
An Assessment of the Influence of Fundamental Factors on Share Prices in Sri Lanka,
Fernando, G.W.J. Sriyantha.
This study analyses certain fundamental factors which are determinants of equity share
prices in Sri Lanka. These factors are earning, growth, leverage, risk and company size.
The literature review of the study have identified various aspects of equity share valuation.
The theoretical and empirical studies have been used to formulate the foundation for the
study. To assess above mentioned fundamental factors on share prices, multiple regression
analyze was used with a log linear model as a cross section analyses related to the period
1993-2001. The sample for the study was selected from companies registered and listed in
the Colombo Stock Exchange. The sample consisted of 40 companies from a group of239
companies in all industries.
Result show that dividends appear to be a powerful influence in determining share prices
than growth and retained earnings. Business risk and financial risk cannot be assessed
because they are redundant variables. Company size is having a considerable influence on
share prices and, accordingly large companies enj oy higher values for shares.
On the basis of findings the following observation was made about the stock market in Sri
Lanka.
"The determinants of valuation of the share prices are not very clear. It goes mainly by
considering dividend and company size factors which are readily measurable. However,
factors like growth and risk cannot be measured with more certainty"
2008-01-01T00:00:00ZOn the systematic of anomalous absorption of partial waves by nuclear optical potential
http://repository.kln.ac.lk/handle/123456789/17154
On the systematic of anomalous absorption of partial waves by nuclear optical potential
Amarasinghe, D.; Munasinghe, J.M.; Piyadasa, R.A.D.
An interesting phenomenon relating to the nuclear optical potential was discovered
(Kawai M & Iseri Y,(1985)) [1] which is called the anomalous absorption of partial
waves by the nuclear optical potential. They found, by extensive computer calculations,
that, for a special combinations of the total angular momentum (j) ,angular
momentum(/) ,energy (E) and the target nuclei(A), the elastic S-matrix elements
corresponding to nucleon elastic scattering become zero. This phenomenon is universal
for light ion elastic scattering on composite nuclei. [2]. It is very interesting that this
phenomenon occurs for the realistic nuclear optical potential and it exhibits striking
systematic in various parameter planes. For example, all nuclei which absorb a partial
l
waves of a definite node lie along a straight in the plane (Re, A 3 ) as shown in the figure
, where Re is the closest approach and A is mass number of the target nucleus.
Theoretical description of this systematic has been actually very difficult, though
attempts have been made by the Kyushu group in Japan. In this contribution, we explain
mathematically the most striking systematic of this phenomenon.
Explanation of the systematic
Partial wave· u 1 ( k, r) of angular momentum I and incident wave number k satisfies the
Schrodinger equation
d21 + [ k2 _ l (l : l ) _ 21 {V(r)+iW(r)}] u,(k,r)= 0
dr r 1i
, where V (r) is the total real part and W (r) is the total imaginary part of the optical
potential. Starting from this equation , one obtains
(1)
lu1(k,r)I2=2 XI du, 12 -g(ru1(r2Jdr (2) dr dr 0
where g(r)= [k2-�� V(r)-l(l
r:1)J. If u1(k, r) is the anomalously absorbed partial
wave, the corresponding S-matrix element is zero and hence in the asymptotic region
I u1(k,r) I is almost constant. Therefore
[1;1' -g(ru1(k,rt ] o (3)
for large r. Now, from (1) and (3), it is not difficult to obtain[3] the equation
_1 !!I 12 -- g'( r) wh (r) 'Jw ( )J 12d (4) 2 u1 - ( ) + 2 h r,., u, r lu,l dr 2g r g(r u,l 0
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Proceedings of the Annual Research Symposium 2008- Faculty of Graduate Studies University of Kelaniya
which is valid for large r , and has been numerically tested in case of an anomalously
absorbed partial waves , where Wh(r) =- 2 W(r) . If W(r) decays much more rapidly n
than V(r) in case of a partial wave under consideration lu,l2 =- g'(
(
r)
)
and by
lu,l dr 2g r
integrating this equation with respect to r, we obtain
I iu1 (k, r)i2 (g(r) 2 = C (5)
,where C is a constant, and the equation (5) is valid for large values of r. In case of
anomalous absorption of the partial wave, I u 1 ( k, r ) I is constant in the asymptotic region
and therefore g(r) is also constant. We have found that for all partial waves
corresponding to a straight line of definite node, g(r) is constant at the respective
I
[l(l + 1)]2 closest approach. For example, at Re = k , g(r) is constant for all partial
waves lying on a straight line in case of anomalous absorption of neutron partial waves
by the nuclear optical potential. Therefore, neglecting the spin-orbit potential , we get
-I I 21tV0[1+exp[([l(/+l)F -1.17A3)]/arr1 =C0
n2 k
where V0 is depth of the real potential and A is the target mass and the optical potential
parameter ar = 0.75 and C0 is a constant. Therefore, in case of neutron, we get the
linear relation
[I (I+ 1)]2
= 1.11 A + C1
k . (6)
where C1 is again a constant. This relation has found to be well satisfied in the cases we
have tested numerically. The equation (6) well accounts for the anomalous absorption of
neutron partial waves by the Nuclear Optical Potential as shown in the figure below.
: [:::::r�;;�����i����:::]::::::::::::::::::::::::] :::::::::--:::::::::::::
1 I I I I I I 7 L----------J------------L---------__ J _ ----------L----------- : ----- ------L----------- ::N :: 6 : ----------: ------------: -----------: _ ___________ :L _ -------i: --------..:---: -----------
;::::" 5 ,1- ------ l l l : : ! - ---,------------r---- -------, ---- ------r--- --------,------------r----------- + : : : I : : : ::-::::: 4 :I- -----------;I ------ I I I I I ------:----- ---"t-------- ----:------------ 1------------:------------
1....1 I I I I I I I
3 lI- ----------1I ------------I -----------1I ------------rI -----------1I ------------rI ----------- 2 ::- ----------1: ------------: -----------1: ------------: -----------1: ------------: -----------
I I I I I I I ,a , 2 3 4 5 6 All3
Gradient of straight line predicted by ( 6) is 1.1 7 and the actual value is 1.1828 . Very
small discrepancy is due to the negligence of the spin-orbit potential.
2008-01-01T00:00:00ZCoupling Shallow Water Equation with Navier-Stokes Equations: A viscous shallow water model
http://repository.kln.ac.lk/handle/123456789/17153
Coupling Shallow Water Equation with Navier-Stokes Equations: A viscous shallow water model
Karunathilake, N.G.A.
The general characteristic of shallow water flows is that the vertical characteristic scale D
is essentially smaller than and typical horizontal scale L .i.e. £ := D << 1 .
L
In many classical derivations, in order to obtain the shallow water approximation of the
Navier-Stokes's Equations, the molecular viscosity effect is neglected and a posteriori is
added into the shallow water model to represent the efficient-viscosity ( a friction term
through the Chezzy formula which involes empirical constants) at the bottom topography.
However, the validity of this approach has been questioned in some applications as the
models lead to different Rankine-Hugoniot curves (see e.g. [1]). Therefore, it can be
useful to consider the molecular viscosity effect directly in the derivation of the shallow
water model. On the other hand the classical shallow water models are derived under the
assumption of slowly varying bottom topographies. Hence, for the description of
incompressible shallow water laminar flow in a domain with a free boundary and highly
varying bottom topography, the classical Shallow Water Equations are not applicable.
The remedy consist of dividing the flow domain into two sub-domains namely, near field
(sub domain with the bottom boundary) and far field (sub domain with the free boundary)
with a slowly varying artificial interface and employ the Navier-Stokes Equations and
Viscous Shallow Water Equations in the near field and far field, respectively.
In this work, we derive a two-dimensional Viscous Shallow Water model for
incompressible laminar flows with free moving boundaries and slowly varying bottom
topographies to employ in the far field. In this approach, the effect of the molecular
viscosity is retained and thereby corrections to the velocities and the hydrostatic pressure
approximations are established. Coupling modified shallow water model with NSE has
been carried out in a separate work.
In order to derive the viscous shallow water model the two-dimensional Incompressible
Navier-Stokes equations in usual notations
au + au2 + auw + ap = ( 2v au) + (v au +V 8 w) , at ax az ax ax ax az az az
aw + auw + 8w2 + ap =-g+ (vau +j.law) + ( 2vau), ---------------------------(1) at ax az az . ax az ax az az
a-w+ a-w= 0. ax az
are employed in the far field with the suitable boundary conditions. On the free surface,
we assume that the fluid particle does not leave the free surface and we neglect the wind
effect and the shear stress. On the artificial boundary we set the conditions according
with the Navier-Stokes solution at the interface. On the lateral boundaries inflow and
outflow conditions are employed. Rescaling the variables with the typical characteristic
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Proceedings of the Annual Research Symposium 2008- Faculty of Graduate Studies University of Kelaniya
scales L and D, the dimensionless form of the Navier-Stokes's equations for shallow
water flows are obtained. Similarly, assuming that the bottom boundary is regular and the
gradient of the free surface remains bounded we obtain the dimensionless boundary
conditions. The second order terms with respect to & in the system are neglected and
asymptotic analysis is carried out under the assumptions, the flow quantities admit linear
asymptotic expansion to the second order with respect to & and the molecular viscosity
of the water is very small. Then, rescaling the depth averaged first momentum equation
of the resulting system and substituting the zeroth order solution for the velocity and the
pressure in it the zeroth order first momentum equation which include the interface
conditions is obtained. Again integrating the continuity equation of the dimensionless
system from z1 to H(t, x ), a more detailed view of the vertical velocity component is
established. Similarly, integrating the vertical momentum equation the dimensionless
system from z1to H(t, x ) and replacing boundary conditions, the second order correction
to the hydrostatic pressure distribution is derived. Then, dropping o(s2) in the system
and switching to the variables with dimensions, the following results are established.
Proposition: The formal second order asymp t ot ic ex p ansion of t he Navier-St okes
Equat ions for t he shallow wat er laminarfl ow is given by
( z -z I ) ou . I ou 2 u(t, x, z) = u(t,x,z1) + I--- -(x, z1 ,t)(z-z1)---(x, z1 ,t)(z-z1)
2h oz 2h oz
h(t,x)+z1 OU
w(t,x,z)=w(t,x,z1)- f -d1]
OX Z=Zt - ou ou
p(t,x,z) = g(h+ z1 -z)-v-(t,x,z)-v-(x,t)
ox ox
wit h t he viscous shallow wat er equations
ah + £(h)= ( w _ u az 1 ) , at ax ax z=Zt
( h) +£ {z h) + £( gh2 J = £( 4v h aJ -rl
'
at ax 8x 2 ax 8x
where r, [ p : +v: +v: -2v : : +u(u: -w) L,,
and z z,(x, t ) is t he
interface.
Concluding remarks
In the zeroth order expansion as well as in many classical shallow water models, the
horizontal velocity does not change along with the vertical direction. In contrast, our first
order correction gives a quadratic expansion to the vertical velocity components retaining
more details of the flow. As many classical models we do not neglect the viscosity effect
but just assume that it is very small. Also, the zeroth order hydrostatic pressure
approximation has been upgraded to the first order giving a parabolic correction to the
pressure distribution.
2008-01-01T00:00:00Z