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Modeling Blood Flow in Veins of Uniform Properties (Giraffe Jugular Vein)

Open Journal of Biophysics 2024年第2期14卷 132-153页

作者： Rogers Omboga Amenya Johanna Kibet Sigey Geoffrey Moriaso Ole Maloiy david mwangi theuri Department of Mathematics and Physical Sciences Dedan Kimathi University of Technology Nyeri Kenya Department of Pure and Applied Mathematics School of Mathematical Sciences Jomo Kenyatta Unversity of Agriculture and Technology Kisii Kenya Institute of Animal Physiology and Biotechnology Research University of Nairobi Nairobi Kenya

This paper models the giraffe’s jugular veins as a uniform collapsible tube from a rigid skull. The equations governing one-dimensional steady flow through such a tube for various conditions have been developed. The effects of inertial and inclination angles that have not been discussed previously have been included. It has been shown that different flows for a uniform tube (vein) are possible. However, this flow matches that of a jugular vein which is supercritical, and the steady solution has been given by the balance between the driving forces of gravity and the viscous resistance to the flow at the right atrium of the heart must be sub-critical for a fixed right-atrium pressure which means that an elastic jump is required to return the flow to sub-critical from the supercritical flow upstream this type of relationship gives rise to flow limitation at the same time given any right atrium fixed pressure there exists a maximum flow rate which when exceeded the boundary conditions of the flow do not hold boundary conditions at the right atrium are not satisfied hence making the steady flow impossible this mechanism of flow limitation is slightly different from the other one in that causes airways through forced expiration from the observation made it is clearly shown that there is an intravascular pressure difference with a change in height.

关键词： Blood Flow Jugular Vein Cross-Sectional Area Supercritical Subcritical Jump

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Effect of Head Position Angles on the Blood Flow in the Jugular Vein of Giraffes

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World Journal of Mechanics 2021年第8期11卷 165-175页

作者： Rogers Omboga Amenya Johanna Kibet Sigey Geoffrey Moriaso Ole Maloiy david mwangi theuri Department of Mathematics and Physical Sciences Dedan Kimathi University of Technology Nyeri Kenya Department of Pure and Applied Mathematics Jomo Kenyatta University of Agriculture and Technology Juja Kenya Department of Animal Physiology and Biotechnology University of Nairobi Nairobi Kenya

The study investigated the effect of the angular position of the head on the blood flow in the jugular vein of giraffes. The vein considered is elastic and collapsible such that its cross-sectional area is not uniform. Transmural pressure causes the blood to move along the vein. Mathematical equations describing the flow were developed, and the vein was considered to be inclined at an angle φ to the horizontal. A finite-difference scheme was used to solve the equations of motion for the flow. The results are presented via relevant tables and plots. Our findings show that a change in the position of the head causes variation in the external pressure, which in turn causes variation in the cross-sectional area of the vein. Moreover, a drop (or increase) in the inertial pressure of the blood may cause the vein to collapse (or distend), which again triggers a change in the pressure.

关键词： Venous Flow Hemodynamics Collapsible Vein Blood Pressure Jugular Vein

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Effect of Head Position Angles on the Blood Flow in the Jugular Vein of Giraffes

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World Journal of Mechanics（力学国际期刊） 2021年第8期

作者： Rogers Omboga Amenya Johanna Kibet Sigey Geoffrey Moriaso Ole Maloiy david mwangi theuri

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Towards Increasing Data Availability for Meteorological Services: Inter-Comparison of Meteorological Data from a Synoptic Weather Station and Two Automatic Weather Stations in Kenya

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American Journal of Climate Change 2021年第3期10卷 300-316页

作者： Richard Muita Paul Kucera Stella Aura david Muchemi david Gikungu Samuel mwangi Martin Steinson Paul Oloo Nicholas Maingi Ezekiel Muigai Mwaura Kamau Kenya Meteorological Department Institute for Meteorological Training and Research Nairobi Kenya University Corporation for Atmospheric Research/National Centre for Atmospheric Research (UCAR/NCAR) Boulder USA

Meteorological data is useful for varied applications and sectors ranging from weather and climate forecasting, landscape planning to disaster management among others. However, the availability of these data requires a good network of manual meteorological stations and other support systems for its collection, recording, processing, archiving, communication and dissemination. In sub-Saharan Africa, such networks are limited due to low investment and capacity. To bridge this gap, the National Meteorological Services in Kenya and few others from African countries have moved to install a number of Automatic Weather Stations (AWSs) in the past decade including a few additions from private institutions and individuals. Although these AWSs have the potential to improve the existing observation network and the early warning systems in the region, the quality and capacity of the data collected from the stations are not well exploited. This is mainly due to low confidence, by data users, in electronically observed data. In this study, we set out to confirm that electronically observed data is of comparable quality to a human observer recorded data, and can thus be used to bridge data gaps at temporal and spatial scales. To assess this potential, we applied the simple Pearson correlation method and other statistical tests and approaches by conducting inter-comparison analysis of weather observations from the manual synoptic station and data from two Automatic Weather Stations (TAHMO and 3D-PAWS) co-located at KMD Headquarters to establish existing consistencies and variances in several weather parameters. Results show there is comparable consistency in most of the weather parameters between the three stations. Strong associations were noted between the TAHMO and manual station data for minimum (r = 0.65) and maximum temperatures (r = 0.86) and the maximum temperature between TAHMO and 3DPAWS (r = 0.56). Similar associations were indicated for surface pressure (r = 0.99) and R

关键词： Meteorological Data Manual Weather Station Automatic Weather Station Correlation

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Towards Increasing Data Availability for Meteorological Services: Inter-Comparison of Meteorological Data from a Synoptic Weather Station and Two Automatic Weather Stations in Kenya

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American Journal of Climate Change（美国气候变化期刊） 2021年第3期

作者： Richard Muita Paul Kucera Stella Aura david Muchemi david Gikungu Samuel mwangi Martin Steinson Paul Oloo Nicholas Maingi Ezekiel Muigai Mwaura Kamau

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