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Search Results: 1 - 10 of 325237 matches for " S Dadzie "
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A volume-based hydrodynamic approach to sound wave propagation in a monatomic gas
S. Kokou Dadzie,Jason M. Reese
Physics , 2009,
Abstract: We investigate sound wave propagation in a monatomic gas using a volume-based hydrodynamic model. In Physica A vol 387(24) (2008) pp6079-6094, a microscopic volume-based kinetic approach was proposed by analyzing molecular spatial distributions; this led to a set of hydrodynamic equations incorporating a mass-density diffusion component. Here we find that these new mass-density diffusive flux and volume terms mean that our hydrodynamic model, uniquely, reproduces sound wave phase speed and damping measurements with excellent agreement over the full range of Knudsen number. In the high Knudsen number (high frequency) regime, our volume-based model predictions agree with the plane standing waves observed in the experiments, which existing kinetic and continuum models have great difficulty in capturing. In that regime, our results indicate that the "sound waves" presumed in the experiments may be better thought of as "mass-density waves", rather than the pressure waves of the continuum regime.
A constitutive model for volume-based descriptions of gas flows
S. Kokou Dadzie,Jason M. Reese
Physics , 2006,
Abstract: We derive the pressure tensor and the heat flux to accompany the new macroscopic conservation equations that we developed previously in a volume-based kinetic framework for gas flows. This kinetic description allows for expansion or compression of a fluid element, and is characterized by a flux of volume that conventional modelling does not account for. A new convective form of transport arises from this new approach, which is due purely to macroscopic expansion or compression. It supplements the conventional transport processes, which are transport due purely to mass motion (classical convective transport) and transport due purely to random motion (diffusive transport). In addition, we show that the thermodynamic parameters of the fluid (temperature and pressure) appear with new non-equilibrium contributions that depend on density variations in the gas. Our new model may be useful for describing gas flows that display non-local-thermodynamic-equilibrium (rarefied gas flows), flows with relatively large variations of macroscopic properties, and/or highly compressible fluids and flows.
On the thermodynamics of volume/mass diffusion in fluids
S. Kokou Dadzie,Jason M. Reese
Physics , 2012,
Abstract: In Physica A vol 387(24) (2008) pp6079-6094 [1], a kinetic equation for gas flows was proposed that leads to a set of four macroscopic conservation equations, rather than the traditional set of three equations. The additional equation arises due to local spatial random molecular behavior, which has been described as a volume or mass diffusion process. In this present paper, we describe a procedure to construct a Gibbs-type equation and a second-law associated with these kinetic and continuum models. We also point out the close link between the kinetic equation in [1] and that proposed previously by Klimontovich, and we discuss some of their compatibilities with classical mechanical principles. Finally, a dimensional analysis highlights the nature of volume/mass diffusion: it is a non-conventional diffusive process, with some similarities to the `ghost effect', which cannot be obtained from a fluid mechanical derivation that neglects non-local-equilibrium structures, as the conventional Navier-Stokes-Fourier model does.
An Evaluation of Sustainability and Subsidy Dependence of Microfinance Institutions in Ghana
F. K. Aveh,R. Y. Krah,P. S. Dadzie
International Business and Management , 2013, DOI: 10.3968/j.ibm.1923842820130601.1090
Abstract: The research aims to explore the understanding of the relationship between sustainability of microfinance institutions (MFIs), subsidy dependence index (SDI) and operational self-sufficiency (OSS).The research study is based on initial exploratory study by analyzing data on 14 executive directors in qualitative interviews and 116 relationship executives in research questionnaires. The microfinance institutions identified were the Financial Non-Governmental Organizations (FNGOs), the Savings and Loans Companies (S&L), the Credit Unions (CUs), the Rural Banks (RBs) and the SUSU Companies. Multiple Regressions which allows for the testing of theories or models established a significant relationship between the Operational Self Sufficiency (OSS) and the predictors, especially the drop-out rate of clients and average loans. The Subsidy Dependence Index (SDI) was calculated for the various types of MFIs and the result was a high dependency ratio especially among the FNGOs. Though the dependency is on the decline, it is very slow indicating that most MFIs will depend on subsidies for a very long time to come. Key words: Subsidy dependence; Sustainability; Operational self-sufficiency; Viability; Microfinance
A volume-based description of gas flows with localised mass-density variations
S. Kokou Dadzie,Jason M. Reese,Colin R. McInnes
Physics , 2006,
Abstract: We reconsider some fundamental aspects of the fluid mechanics model, and the derivation of continuum flow equations from gas kinetic theory. Two topologies for fluid representation are presented, and a set of macroscopic equations are derived through a modified version of the classical Boltzmann kinetic equation for monatomic gases. The free volumes around the gaseous molecules are introduced into the set of kinetic microscopic parameters. Our new description comprises four, rather than three, conservation equations; the classical continuity equation, which conflates actual mass-density and number-density in a single equation, has been split into a conservation equation of mass (which involves only the classical number-density of the gaseous particles) and an evolution equation purely of the mass-density (mass divided by the actual volume of the fluid). We propose this model as a better description of gas flows displaying non-local-thermodynamic-equilibrium (rarefied flows), flows with relatively large variations of macroscopic properties, and/or highly compressible fluids/flows.
Surveillance of viral haemorrhagic fevers in Ghana: entomological assessment of the risk of transmission in the northern regions
M Appawu, S Dadzie, H Abdul, H Asmah, D Boakye, M Wilson, D Ofori-adjei
Ghana Medical Journal , 2006,
Abstract: Objectives: To assess the risk of transmission of viral haemorrhagic fevers in northern Ghana. Design: A two-year cross-sectional entomological study was carried out in four communities in the northern part of Ghana. Standard WHO methods were used to collect adult and larvae of Aedes mosquitoes to estimate man-vector contact rates and larval indices. Results: A total of 2804 households were surveyed to estimate larval indices and man-vector contacts of potential vectors of viral haemorrhagic fevers such as Yellow fever and Dengue. Over 56% households in each study site were positive for Aedes larvae. Relatively higher Breteaux index (BI) and Container index (CI) were estimated in Damongo (BI: 180 and CI: 44.8) and Jirapa (BI: 149.7 and CI: 41.5) compared to Tumu (BI: 76.1 and CI: 19.5) and Bolgatanga (BI: 72.4 and CI: 20.6). Man-biting rates of 9.8 and 18.5 bites /man/hour were estimated for Damongo and Jirapa respectively whilst Bolgatanga recorded 10 B/M/H. Generally, man-vector contact rates in all the study sites were higher during the dry season than the wet season. Larval indices showed seasonal variations and the dry season was identified as the high-risk period for transmission of viral haemorrhagic fevers and possible disease outbreaks. No flavivirus was detected in the 2034 Aedes mosquitoes from the study sites by RTPCR. Conclusions: Aedes mosquito larval densities and adult biting rates, in all the study areas were sufficient to promote outbreaks of viral haemorrhagic fevers.
Developmental State and Economic Development: Prospects for Sub-Saharan Africa
Richard B. Dadzie
Journal of Sustainable Development , 2012, DOI: 10.5539/jsd.v5n9p14
Abstract: This paper will argue that the demonization of sub-Saharan African state proposed and enacted by neoliberal institutions during and since the era of structural adjustment has no historical foundations. In making this argument, the history of development thinking prior to and after World War II will be analyzed to show that the state was and continues to be instrumental in economic development. Finally, drawing on the contributions of heterodox development economists, prospects for re-integrating the sub-Saharan African state to bolster economic development will be assessed by drawing on the development experiences of East Asia’s high performing economies.
PROVIDING INFORMATION COMMUNICATION TECHNOLOGY SUPPORT TO DISTANCE EDUCATION STUDENTS: A Case of The University of Ghana, Legon
Beatrice K. AGYEMANG,Perpetua DADZIE
The Turkish Online Journal of Distance Education , 2010,
Abstract: A study to investigate the current state of Information Communication Technology policy of the University of Ghana Distance Education (DE) programme and the extent of awareness and use of ICTs in general by the DE learners was carried out. The survey methodology was adopted using questionnaire and interview instruments. Respondents were made up of 120 DE students, the coordinator of the DE programme, and 5 workers at the DE unit. The questionnaires were distributed to all the 120 students while the workers responded to a semi-structured interview. The data was analyzed using descriptive statistics (percentage frequency distribution and examining relationships). The main findings of the study revealed that there was a policy statement on providing ICT-based support to the DE learners; however, this policy has not yet been implemented. Most of the DE students were fully aware of ICT and majority of them use the internet across the regions. The students had positive attitude towards ICTs in that they deemed it necessary in the course of their studies and were willing to pay for ICT services. The main barriers identified that could affect the usefulness of the various ICTs were electricity, cost and accessibility. The study recommends among others, the forging of partnerships between distance education programmes and ICT companies, the networking of DE centres and the use of diverse ICT facilities, among others.
Providing visualisation support for the analysis of anatomy ontology data
Aba-Sah Dadzie, Albert Burger
BMC Bioinformatics , 2005, DOI: 10.1186/1471-2105-6-74
Abstract: The Edinburgh Mouse Atlas Project stores the developmental stages of the mouse embryo in anatomy ontologies. This project is looking at the use of visual data overviews for intuitive analysis of the ontology data.A prototype has been developed that visualises the ontologies using directed acyclic graphs in two dimensions, with the ability to study detail in regions of interest in isolation or within the context of the overview. This is followed by the development of a technique that layers individual anatomy ontologies in three-dimensional space, so that relationships across multiple data sets may be mapped using physical links drawn along the third axis.Usability evaluations of the applications confirmed advantages in visual analysis of complex data. This project will look next at data input from multiple sources, and continue to develop the techniques presented to provide intuitive identification of relationships that span multiple ontologies.Improvements in technology have resulted in the ability to perform increasingly complex experimental research, generating large amounts of multi-dimensional data. Research in biology today involves the exploration and analysis of the large, shared databases available to the wider scientific community. This reduces duplication of effort and allows more extensive research to be done, by providing independent data sources for verifying hypotheses formulated.Conversely, technology has been unable to manage the data it has spawned; data management, analysis and visualisation tools struggle to meet requirements [1]. This is due largely to the constantly evolving information needs of the biologists working with the increasingly large amounts of heterogeneous data generated [2]. Bioinformatics developed to exploit information technology in biological data analysis [3,4].This paper looks at the development of visual solutions for intuitive analysis of anatomy ontologies. The primary data source is the Edinburgh Mouse Atlas Project (EM
Selection of an ideal mesh size for the cracking unit of a palm kernel processing plant
PY Andoh, WA Agyare, J Dadzie
Journal of Science and Technology (Ghana) , 2010,
Abstract: One of the main problems associated with cracking of palm nut is the mixture of small Tenera and the big Dura variety nuts. In general, low yield of about 40% is obtained from cracking the mixture of Dura-Tenera nuts. In cracking the mixture, most of the Tenera nuts are not cracked when a large sieve size is used. When the sieve size is small, the Dura kernels get broken, thereby affecting the quality of the processed kernel oil. Hence the objective of this work was to develop a model for selecting a suitable sieve size that can be used to crack the nut in order to increase productivity and also improve the quality of the palm kernel oil. Series of experiments carried out confirmed the need for separation of nuts before cracking and also the need to select an ideal sieve size for each type of nut. In conclusion, it was established that separating the two nut varieties before cracking led to a significant (p< 0.01) increase in cracking efficiency of up to about 90% thereby increasing the productivity by 40% and making an economic gain of GH¢ 1.07 (US$0.98, October, 2008) per every 50 kg nut processed.
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