Articles: Department of Mathematics, Computing & Information Technology
http://repository.embuni.ac.ke/handle/123456789/611
Journal articles for Mathematics, Computing & Information TechnologyFri, 14 Aug 2020 10:52:57 GMT2020-08-14T10:52:57ZHybrid Cram er-Rao bound of direction finding, using a triad of cardioid sensors that are perpendicularly oriented and spatially collocated
http://repository.embuni.ac.ke/handle/embuni/2373
Hybrid Cram er-Rao bound of direction finding, using a triad of cardioid sensors that are perpendicularly oriented and spatially collocated
Kitavi, Dominic M.; Wong, Kainam Thomas; Lin, Tsair-Chuan; Wu, Yue Ivan
Cardioid microphones/hydrophones are highly directional acoustical sensors, which enjoy easy
availability via numerous commercial vendors for professional use. Collocating three such cardioids
in orthogonal orientation to each other, the resulting triad would be sharply directional yet
physically compact, while decoupling the incident signal’s time-frequency dimensions from its
azimuth-elevation directional dimensions, thereby simplifying signal-processing computations.
This paper studies such a cardioid triad’s azimuth-elevation direction-of-arrival estimation accuracy,
which is characterized here by the hybrid Cram er-Rao bound. This analysis allows the cardioidicity
index (a) to be stochastically uncertain, applies to any cardioidic order (k), and is valid for
any real-valued incident signal regardless of the signal’s time-frequency structure.
Mon, 01 Jul 2019 00:00:00 GMThttp://repository.embuni.ac.ke/handle/embuni/23732019-07-01T00:00:00ZSocio-Demographic Factors And Knowledge Influencing Associated With ORS Use For Diarrhoea In Children At Miathene Sublocation, Meru County, Kenya
http://repository.embuni.ac.ke/handle/embuni/2372
Socio-Demographic Factors And Knowledge Influencing Associated With ORS Use For Diarrhoea In Children At Miathene Sublocation, Meru County, Kenya
Ngechu, Judith Naita; Okeyo, Hesbon Okello; Ongeso, Abednego; Wanyoike, Peter Kamau; Atitwa, Edwin
Oral rehydration solution is the gold standard treatment option in childhood diarrhoea though there are
other practices like use of rice water, water sugar mixtures, continuous breast feeding for under six months and
complementary feeding have management well dehydration due to diarrhoea. The study adopted mixed methods for data
collection and 301 caregivers were interviewed and data analyzed using SPSS version 25. Bivariate analysis was
conducted to examine possible associations between predictor variables and ORS uptake. This was done using Pearson’s
Chi Square. Association was considered significant when p-value is less than 0.05. Results indicated that children average
age was 28.44. About 50.2% of the respondents utilized oral rehydration solution, the utilization was significantly
associated with socio-demographic variables such as age with (p-value =0.018), marital status (p-value =0.001), level of
education (p=0.015), monthly income (p=0.046); caretaker’s variables such knowledge on how ORS is given (p=0.0001),
amount oral rehydration solution given to child (p=0.011) and uses of oral rehydration solution (p=0.036), therefore,
policy makers need to advice the government on different approaches to diarrhea management, which involves use of oral
rehydration solution packets. Efforts are needed to incorporate herbalists into diarrhea case management programs so
that they can also promote the use of oral rehydration solution for prevention of dehydration from diarrhea.
Fri, 01 May 2020 00:00:00 GMThttp://repository.embuni.ac.ke/handle/embuni/23722020-05-01T00:00:00ZA uniform circular array of isotropic sensors that stochastically dislocate in three dimensions—The hybrid Cramer-Rao bound of direction-of-arrival estimation
http://repository.embuni.ac.ke/handle/embuni/2371
A uniform circular array of isotropic sensors that stochastically dislocate in three dimensions—The hybrid Cramer-Rao bound of direction-of-arrival estimation
Wong, Kainam Thomas; Ndiku, Morris Zakayo; Kitavi, Dominic M.; Lin, Tsair-Chuan
An array’s constituent sensors could be spatially dislocated from their nominal positions. This
paper investigates how such sensor dislocation would degrade a uniform circular array (UCA) of
isotropic sensors (like pressure sensors) in their direction-ﬁnding precision. This paper analytically
derives this direction ﬁnding’s hybrid Cram er-Rao bound (HCRB) in a closed form that is
expressed explicitly in terms of the sensors’ dislocation parameters. In the open literature on UCA
direction ﬁnding, this paper is the ﬁrst to be three-dimensional in modeling the sensors’ dislocation.
Perhaps unexpectedly to some readers, sensor dislocation could improve and not necessarily
degrade the HCRB; these opposing effects depend on the dislocation variances, the incident
source’s arrival angle, and the signal-to-noise power ratio—all analyzed rigorously in this paper.
Interesting insights are thereby obtained: (a) The HCRB is enhanced for the impinging source’s
polar arrival angle as the sensors become more dislocated along the impinging wavefront due to
aperture enlargement over the stochastic dislocation’s probability space. (b) Likewise, the HCRB is
improved for the azimuth arrival angle as the sensors become more dislocated on the circular
array’s plane, also due to aperture enlargement. (c) In contrast, sensor dislocation along the incident
signal’s propagation direction can only worsen the HRCBs due to nuisance-parameter effects
in the Fisher information. (d) Sensor dislocation orthogonal to the array plane must degrade the
HCRB for the azimuth arrival angle but could improve the HCRB for the polar arrival angle.
Mon, 01 Jul 2019 00:00:00 GMThttp://repository.embuni.ac.ke/handle/embuni/23712019-07-01T00:00:00ZCramer-Rao Bound of Direction Finding Using Uniform Arc Arrays
http://repository.embuni.ac.ke/handle/embuni/2370
Cramer-Rao Bound of Direction Finding Using Uniform Arc Arrays
Nyokabi, Veronicah; Kitavi, Dominic M.; Ngari, Cyrus G.
Direction-of-Arrival estimation accuracy using arc array geometry is considered in this paper.
There is a scanty use of Uniform Arc Array (UAA) in conjunction with Cram er-Rao bound (CRB)
for Direction-of-Arrival estimation. This paper proposed to use Uniform Arc Array formed from
a considered Uniform Circular Array (UCA) in conjunction with CRB for Direction-of-Arrival
estimation. This Uniform Arc Array is obtained by squeezing all sensors on the Uniform Circular
Array circumference uniformly onto the Arc Array. Cram er-Rao bounds for the Uniform Arc
Array and that of the Uniform Circular Array are derived. Comparison of performance of the
Uniform Circular Array and Uniform Arc Array is done. It was observed that Uniform Arc Array
has better estimation accuracy as compared to Uniform Circular Array when number of sensors
equals four and ve and azimuth angle ranging between π 9 7 and π and also 18 10 9 π and 25 18π.
However, UCA and UAA have equal performance when the number of sensors equals three and the azimuth angle ranging between 0 and 2π. UCA has better estimation accuracy as compared
to UAA when the number of sensors equals four and ve and the azimuth angle ranging between
π 2 and π and also 32 π and 2π
Tue, 01 Jan 2019 00:00:00 GMThttp://repository.embuni.ac.ke/handle/embuni/23702019-01-01T00:00:00Z