Showing papers by "University of Bahrain published in 1995"

Lee distance and topological properties of k-ary n-cubes

Abstract: In this paper, we consider various topological properties of a k-ary n-cube (Q/sub n//sup k/) using Lee distance. We feel that Lee distance is a natural metric for defining and studying a Q/sub n//sup k/. After defining a Q/sub n//sup k/ graph using Lee distance, we show how to find all disjoint paths between any two nodes. Given a sequence of radix k numbers, a function mapping the sequence to a Gray code sequence is presented, and this function is used to generate a Hamiltonian cycle. Embedding the graph of a mesh and the graph of a binary hypercube into the graph of a Q/sub n//sup k/ is considered. Using a k-ary Gray code, we show the embedding of a k(n/sub 1/)/spl times/k(n/sub 2/)/spl times/.../spl times/k(n/sub m/)-dimensional mesh into a Q/sub n//sup k/ where n=/spl Sigma//sub i=l//sup m/n/sub i/. Then using a single digit, 4-ary reflective Gray code, we demonstrate embedding a Q/sub n/ into Q/sub [n/2]//sup 4/. We look at how Lee distance may be applied to the problem of resource placement in a Q/sub n//sup k/ by using a Lee distance error-correcting code. Although the results in this paper are only preliminary, Lee distance error-correcting codes have not been applied previously to this problem. Finally, we consider how Lee distance can be applied to message routing and single-node broadcasting in a Q/sub n//sup k/. In this section we present two single-node broadcasting algorithms that are optimal when single-port and multi-port I/O is used. >

Transport of hormones in the phloem of higher plants

Abstract: Evidence for the translocation of auxins, gibberellins, cytokinins and abscisic acid and some of its metabolites in the phloem is reviewed. Problems associated with collection of sieve tube exudates and analysis of samples are discussed as are some of the possible functions of the translocated hormones.

A Comparison of ID3 and Backpropagation for English Text-To-Speech Mapping

Abstract: The performance of the error backpropagation (BP) and ID3 learning algorithms was compared on the task of mapping English text to phonemes and stresses. Under the distributed output code developed by Sejnowski and Rosenberg, it is shown that BP consistently out-performs ID3 on this task by several percentage points. Three hypotheses explaining this difference were explored: (a) ID3 is overfitting the training data, (b) BP is able to share hidden units across several output units and hence can learn the output units better, and (c) BP captures statistical information that ID3 does not. We conclude that only hypothesis (c) is correct. By augmenting ID3 with a simple statistical learning procedure, the performance of BP can be closely matched. More complex statistical procedures can improve the performance of both BP and ID3 substantially in this domain.

Novel electronically tunable C-multipliers

Abstract: A simple circuit is given for realising an electronically tunable grounded capacitance multiplier. It employs two operational transconductance amplifiers (OTAs), an operational amplifier (OA) and a grounded capacitor (C). The circuit provides wide-range linear tuning of C-values through the bias control of OTAs. This multiplier is easily modified to realise a low-component floating C-multiplier. The circuits are MOS/Bi-MOS compatible and present definite advantages over the available multipliers. Experimental results are included.

Temporal variations in four species of intertidal foraminifera, Bahrain, Arabian Gulf

Abstract: This study deals with the temporal variations in four infaunal foraminiferal taxa sampled monthly over a 25-month period (February 1991 February 1993 inclusive) from the lower intertidal zone on the east coast of Bahrain, Arabian Gulf. Standing crop, relative abundance and changes in species diversity and annual production of tests were measured for Ammonia beccarii, Elphidium advenum, Brizalina pacifica and Nonion sp.. Additionally, the greatest diameter of each individual of A. beccarii was measured to determine monthly size changes and periods of reproduction. An attempt was made, through the use of replicate sampling, to determine homogeneity or patchiness (similarity) in species distributions and abundance patterns. Major changes are noted in species diversity and abundance between July and August 1992. The standing crop of the whole assemblage and of A. beccarii doubled, that of E. advenum increased three to four times and, for B. pacifica and Nonion sp., the increase varied between 30 and 100 times. Overall, standing crop varied from 1-118 per 10cm3 and annual production of tests ranged from 2 to 2550 per 10cm3. A. beccarii is thought to reproduce throughout the year. Species diversity is characteristically low in this hypersaline habitat. Whereas the living assemblage is dominated by infaunal taxa, the dead assemblage is composed largely of transported epiphytic taxa, so the two are very different. INTRODUCTION The objective of the study was to monitor temporal changes in selected infaunal foraminiferal species from a subtropical lower intertidal zone in an arid climatic region. Replicate samples were taken to investigate homogeneity or patchiness of species distributions and their abundance patterns. Sampling was carried out monthly over a 25-month period in order to determine periods of reproduction, annual production of tests and changes in species diversity. The collection site is located in a bay on the east coast of Bahrain (text-fig. 1); the area is microtidal (

An investigation into a falling film type cooling tower

Abstract: A model for a falling film type cooling tower has been developed to investigate the effect of tower parameters as well as the effect of liquid-side thermal resistance on the tower performance. The energy equation is used to determine the temperature distribution across the liquid film. The heat and mass transfer processes between the liquid film and air bulk are described using three ordinary differential equations. The energy equation was solved using a finite difference Crank-Nicolson scheme. The heat and mass transfer equations were solved using the Runge-Kutta method. The results obtained show that an increase in tower characteristic KaV/L under the same conditions improves the tower performance. The converse is true in the case of increased water to air mass flowrate ratio, L/G. The Lewis number, Le, shows no significant effect on the tower performance. The effect of tower parameters as well as the water inlet temperature on the liquidside Nusselt number and the tower effectiveness was also studied. The results show very insignificant changes in Nusselt number, whereas the effectiveness increases with increasing KaV/L and reduces with L/G, but very insignificant changes occur with Le. The present model is also compared with Merkel's equation. Under the same conditions and with Le equal to unity, the results of the Merkel equation shows a smaller approach than that obtained by the present model.

Parallel LOD methods for second order time dependent PDEs

Abstract: Time dependent problems in Partial Differential Equations (PDEs) are often solved by the Method Of Lines (MOL). In many important instances, the exact solution of the resulting system of Ordinary Differential Equations (ODEs) satisfies recurrence relations involving the matrix exponential function. This function is approximated by a new type of rational function possessing real and distinct poles which, consequently, readily admits a partial fraction expansion thereby allowing the distribution of the work in solving the corresponding linear algebraic systems in essentially Backward Euler-like solves on concurrent processors. Locally One Dimensional (LOD) splitting methods with enhanced parallelization are developed for multispace problems utilizing Strang-like splitting techniques. The use of rational approximants with distinct real poles in the temporal direction, in collusion with splitting techniques in the spatial directions, creates the potential for efficient coarse grain time-stepping parallel algorithms on MIMD machines. The resulting parallel algorithms possess appropriate stability properties, and are implemented on various parabolic and hyperbolic PDEs from the literature in higher space dimensional problems.

Object-oriented programming for structured procedural programmers

Abstract: Object orientation is attracting much attention these days but may still be unfamiliar to some. This tutorial illustrates the differences between the object-oriented and structured-procedural programming (SPP) paradigms using working programs. It also shows how to migrate from the SPP methodology to object technology. >

Cyclic voltammetric studies of tris(alkylisocyanide)bis(tertiary phosphine)cobalt(i) complexes

Abstract: Synthesis and characterization of tris(alkylisocyanide)bis(triarylphosphine)cobalt(I) complexes, [Co(CNR)3(PR3)2]ClO4, has been extended to include CNR = CNCMe3, PR3 = P(C6H4CF3-p)3, P(C6H4F-p)3, P(C6H4Me-p)3; PR3 = PPh3, CNR = CNC6H11, CNCH2Ph, CNC4H9-n. Reduction of [Co(CNCMe3)4H2O](ClO4)2 did not occur with PR3 = P(C6H4NMe2-p)3 and P(C6F5)3. Solution and solid state structures of the new [Co(CNR)3(PR3)2]ClO4 complexes appear to be distorted disubstituted trigonal bipyramidal examples with the phosphine ligands in axial positions, but the extent of distortion from rigorous D 3h symmetry in solution appears to vary for different complexes. Oxidation potentials, E1/2, measured in CH3CN, for the oxidation of Co(I) to Co(II), are essentially independent of the RNC ligands, remaining within the narrow range of +0.20 to +0.25V for [Co(CNR)3(PPh3)2]ClO4, R = CMe3, CHMe2, C6H11, CH2Ph, C4H9-n. Variation of the tertiary phosphine ligands has a pronounced effect on the E1/2 values, which range from +0.03...

The linke turbidity factor and Ångström coefficient in humid climate of Bahrain

Abstract: By using solar spectrum intensity measurements, the aerosol optical depth and the atmospheric turbidity coefficients of Bahrain's atmosphere, i.e. the Linke turbidity factorT and Angstrom coefficientβ, have been calculated at discrete wavelengths from 350 to 800 nm. A linear regression model was fitted forT versusβ for such a humid climate and it was compared to models reported for desert (Dhahran, Saudi Arabia) and temperate (Avignon, France) climates. A relationship between the linear regression slope,b, and the function of concentration and size distribution of particles,α, over wide wavelength range was found.

Solution to a problem of A. D. sands

Abstract: If a finite cyclic group is a direct product of its subsets such that the cardinality of one factor is a product of two primes and the others are of prime cardinalities, then at least one of the factors is a direct product of a subset and a proper subgroup of the group. This settles a 30 years old problem of A. D. Sands,.

Extraction of El-Lajjun Oil Shale

Abstract: Extraction of the bitumen fraction of El-Lajjun oil shale was carried out using 17 different solvents, pure and combined. Out of all the solvents used, toluene and chloroform were found to be the most efficient for extraction of the bitumen to perform the major part of the experiments. This selectivity was based on the quality and quantity of the yield and on the quantity of solvent recovered. Extraction was carried out using a Soxhlet extractor. For complete recovery of solvent the extract phase was subjected to two stages of distillation, simple distillation followed by fractional distillation, where different cuts of oil were obtained. It was found that an optimum shale size of 1.0 mm offered better solvent recovery. One hour was the optimum time needed for complete extraction. The yield of oil was determined from the material balance gained from fractional distillation after testing for the existence of any traces of solvent trapped in the different cuts by using a gas chromotography techniqu...

Accounting standards and corporate financial reporting in india

Abstract: This study makes a critical examination of the present accounting standard setting process and current issues and practices of corporate financial reporting (CFR) in an Indian context by referring to 95 annual reports of large sized companies. It is found that Indian accounting standards have many alternative accounting choices which make financial statements of companies less comparable. The Accounting Standard Board (ASB) has issued 12 definite accounting standards, yet none of them has been reviewed. The membership of ASB lacks proper representation particularly from the users side. The standard setting process has deficiencies in the absence of public hearing and the machinery for enforcement of accounting standards is not apparent. While a review of CFR shows a strong tendency for companies to follow strict legal requirements in the disclosure and preparation of financial statements, there is much diversity in voluntary reporting practice particularly with respect to value added accounting, reporting by segments, inflation accounting, human resource accounting, and corporate social performance reporting, and there has been a tendency towards minimum disclosure. The study suggests that, to improve standards the Institute of Chartered Accountants in India should establish a Financial Reporting Council (FRC) to oversee ASB and to prepare a conceptual framework for financial reporting purposes.