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- ItemThe preparation of low-temperature fusion enamel coatings for corrosion control using local raw materials(2007-06-19) Danquah, AndrewsAn attempt has been made in this study to formulate materials for low-temperature fusion enamel coating from local raw materials and borax that can be applied directly onto steel substrate for corrosion control. Mfensi and Afari clays, and the Mouri feldspar were mixed in various proportions with borax to form various batches. The batches were mixed with water to form slips which were used to coat already prepared steel surfaces and were allowed to dry in the open. The coated steel plates were again dried in the oven and fired at temperatures of 800oC, 850oC and 900oC to mature. The coatings were observed and also physico-chemical tests were conducted to evaluate some properties of the coatings. The coatings matured and adhered very well to the substrate at 850oC and 900oC and showed good hardness and thermal shock resistance as well as good corrosion resistance in brine and 10% nitric acid. The coatings hardness at the above temperatures were between 7 and 8 on the Mohs scale and 70-90 on the BHN(1/60). The coatings thickness at these temperatures was between 0.42mm and 0.5mm. They were able to resist fifteen cycles of heating and quenching from 400oC. The coatings prepared with the Afari clay with its higher content of iron oxide showed better results in terms of hardness and thermal shock resistance than those prepared with the Mfensi clay. However the coatings fired at 800oC did not fuse properly and hence did not show good adhesion to the substrate. They showed a hardness of 4-6 on the Mohs scale and failed on the Brinnel Hardness Tester.
- ItemImpact of heavy goods vehicles on safety and traffic management in the Tamale Metropolis(2008-08-17) Keketsyor, Mawutor KofiThis report presents the results of a study to determine the Impact of Heavy Goods Vehicles on safety and traffic management in the Tamale Metropolis from 2005 to 2007. From 1991 to 2006, a total of 235,559 vehicles were involved in road traffic crashes nationwide, 11.8% of which were HGVs. Within the same period, 21626 people died as a result of their involvement in road traffic crashes throughout the country. 11.2% of these fatalities were HGV-related. On the northern corridor of the national trunk road network, freight transportation continues to grow, largely as a result of trade liberalization in the West African sub region. This appears, in part, to have impacted on safety as the main urban centres in the North have recorded a significant number of HGV-related accident cases. Tamale, the Northern Regional capital has had its fair share of these problems. The objectives of the study were to establish the characteristics of accidents involving HGVs, to determine whether HGVs are prone to specific types of accidents, and to identify challenges posed to traffic management as a result of the presence of HGVs on some selected roads in the CBD. Accident data for the study was collected from the files of the Motor Traffic and Transport Unit (MTTU) of the police service in Tamale, and the Building and Road Research Institute (BRRI) accident database in Kumasi. Manual Classified Traffic Counts were also conducted on the Bolga, Daboya, Kumbungu, Dagomba and Gukpegu Roads. Travel Time and Delay Studies were conducted on the roads mentioned to determine the duration, location and causes of delays. Discussions were also held with DUR officials in connection with pertinent traffic management issues on the roads studied. The results of the study show that there was a rapid increase in the number of HGV-related accident cases within the period with 21% out of a total of 76 cases occurring in 2005, 33% in 2006 and 46% in 2007. Fatalities also increased from, 26% in 2005, 29% in 2006 to 45% in 2007 out of a total of 93. The year 2006 recorded the highest proportion (18 out of 45) of people that were hospitalised as a result of their involvement in HGV-related accidents. Sixty-two (62) out of 130 casualties also sustained minor injury during 2006. The number of vehicles involved in HGV-related accidents increased in percentage terms from 20% in 2005, 28% in 2006 to 52% in 2007. It has also been revealed that majority of HGV-related accident cases occurred on link sections rather than at intersections, and that HGVs are prone to Rear-end and Ran-off road types of accidents. The Bolga IMPACT OF HEAVY GOODS VEHICLES ON SAFETY AND TRAFFIC MANAGEMENT [N THE TAMALE METROPOLIS - MSc. THESIS and Kumbungu Roads were identified as the most prone to HGV-related accidents. Congestion occurs on the Kumbungu Road between the Bonzali Junction and the Market Circle Road due to a backflow, onto the Kumbungu Road, of vehicles entering the Savelugu Terminal. The situation is compounded by slow-moving light trucks and inadequate NMT facilities which together creates conflicts on this section of the road. It has been recommended that the remaining sections of the second ring road be developed to the required standard to accommodate HGVs so that those HGVs destined for Bolga and beyond would no longer go through the city centre. In addition, the Metropolitan Authorities in collaboration with the Department of Urban Roads, and Goods Supply Companies should set up a bulk-breaking terminal along the Ring Road so that goods destined for Tamale can be delivered to the city centre by smaller vehicles.
- ItemCorrelation between Dynamic Cone Penetrometer (n-Value) and Allowable Bearing Pressure of Shallow Foundation Using Model Footing(2008-08-18) Dzitse-Awuku, DavidAn allowable bearing pressure is one of the most important basic parameters to be determined before the design and construction of foundations for civil engineering structures. The conventional methods of estimating this parameter is becoming relatively expensive and time consuming for small scale projects such as residential buildings. The DCP is a versatile equipment that may be applied to obtain the bearing capacity. However, currently, there are no reliable correlations between the DCP test results and the bearing capacity. This project was undertaken to develop a reliable correlation between the Dynamic Cone Penetrometer (DCP) n-value (blows/100mm) and the allowable bearing pressure qati (kN/m2) for shallow foundations using a model footing. In this work, compacted soil sample of different dry densities in a mould was loaded with a model footing until the sample yielded. On the same sample, DCP testing was performed at two locations to determine the average D- value (mm/blow). Triaxial samples were also taken for triaxial test. Results from the triaxial test were used to calculate ultimate bearing capacity using Terzaghi bearing equation. The measured DCP D-value (mm/blow) was processed into n-value (blows/100mm) which is the standard form of recording the DCP test results in the field. The results were analysed and a correlation qau=48n + 57, with a coefficient of correlation, R2=0.98 was obtained for the model footing. This correlation was similar to the correlation between the n-value and the allowable bearing pressure computed using the Terzaghi approach, except that the Model underestimated the allowable bearing pressure by a constant value of 165 kN/m2 for all values of n.
- ItemAvailability of natural gravel for road construction in Ghana(2008-08-23) Addison, George KodwoMost road pavements in Ghana have for many years been built of natural gravel as the subbase and base layers. Natural gravel are the most economical material for road construction when available within economic haulage distances. However, there has been a gradual shift to the use of a blend of natural gravel and other materials (stabilization) or crushed stone as the layer materials for subbase and base. In addition, various studies have been done to improve the engineering properties of natural gravel underscoring the difficulty of finding suitable material for construction in Ghana. However the extent of the problem is unknown. This study evaluated some material properties (CBR, grading and Atterberg limits) of natural gravel samples from 454 borrow pits distributed throughout the country for their suitability or otherwise for road construction as a subbase, base and Otta seal. Each material property was compared with G30, G40, G60 and G80 MoT specifications. The ones meeting the criteria were denoted as passed or failed if otherwise. The results showed that it is difficult getting natural gravel meeting the specification for G80 base material. However, there is significant improvement when a relaxed specification of G60 is used. This indicated grading plays a very important part in deciding whether a natural gravel material meets specification or not. Generally Western Region had the greatest difficulty of meeting grading requirement. The overall proportion of samples meeting the requirements of subbase and base are 26% and 2% respectively. It is almost impossible to find a natural gravel pit meeting the requirements of Otta seal without processing. Most natural gravel in the country will need two cycles of screening for them to meet the gradation requirement for Otta seal.
- ItemSignal Radiation leakage of power line Communication Systems(2009-07-15) Sekyere, FrancoisThe usage of power line communications, PLC over the low-voltage electrical power supply networks gives an alternative for the telecommunication access. Initially power lines were used for controlling appliances, however with the recent technology advancements the power lines are now able to compete successfully with other relatively stable home networking technologies like wireless and phone line. Despite the advantages that PLC can offer, it is associated with the major cause of harmful interference to other users of the wireless spectrum. PLC risks not living up to its full development and success unless proper standards and regulations are developed globally. The objective of this thesis is the analysis of problems related to electromagnetic compatibility of broadband power line communications. The study comprises both theoretical and experimental analysis. The experimental work was conducted in the form of field measurements, performed in real power line communication network. For the theoretical work, PLC networks were modeled and simulated with the Numerical Electromagnetics Code (NEC).
- ItemSanitation in basic Schools - a case study in Tano-South District(2009-08-18) Gyabaah, DanielThe Community Water and Sanitation Agency is mandated by the Government of Ghana to implement the Small Towns Water Supply and Sanitation Project. The overall goal is to reduce poverty through improvement of the health status of citizens living in rural areas and small towns by providing them with potable water and improved sanitation facilities. The aim of the study was therefore to come out with the current water and sanitation situations in schools in Tano South District of Ghana. The research has revealed that, the coverage of water and sanitation facilities in schools in the district are low; since the results showed that 53 % of the schools were without toilets facilities, while 83 % were without safe water. This was contrary to Ministry of Education Youth and Sports /Ghana Education Service Policy which requires that every school should have adequate water and sanitation facilities. The majority of the schools, 71 % burn then- refuse during schools' instructional hours, which causes environmental pollution. The survey revealed that 30.0 % of the pupils washed their hands with soap before eating while 70.0% washed their hands without soap before eating. This means that only 30.0 % of the school children were practicing an essential do-it-yourself vaccine which is the effective way of interrupting the transmission of disease agents. The least hygienic practice that was carried out in the district was hands washing after collection of refuse. The percentage of pupils who washed their hands with soap was 24.0% with 54.0% using only water to wash their hands. The remaining 22.0 % did not wash their hands. Indicator weighting system for sanitary facilities based on hygienic status, convenience, adequacy and technology type showed that 15 schools had total scores between 10 and 14 points out of 15 points for availability of human excreta facilities, 12 schools had total scores between 8 and 10 points out of maximum of 10 points for solid waste collection facilities and disposal methods. Similarly, 6 schools had total scores between 70 points and 100 points with six schools also scoring less than 50 points, for the hygiene behaviour and practices of school children and 10 schools scored at most 20 points out of 40 points for food vendors. The study revealed that 65.0 % of the SHEP Co-ordinators were not performing their duties effectively due to lack of funds, personnel and logistics, and this could affect the sanitation and hygiene of the schools.
- ItemIdentifying and Incorporating Indigenous Concepts into Integrated Water Resources Management within the White Volta Basin in Ghana(2009-08-24) Kogo, Emmanuel SungnumahThe enactment of the Water Resources Commission (WRC) Act in Ghana in 1996 has in effect abolished the pre-1996 customary regime which allowed the ownership of water to be handled by stools, skins, society, families among others. In place of the customary regime, the state has taken over the ownership, control, and management of water by establishing the WRC. The research aimed to identify and determine effective Indigenous Forms of Water Resources Management (IFWRM) and suggest ways of incorporating them into formal Water Resources Management (WRM) within the White Volta River Basin (WVB) in Ghana. Six communities were selected for the study. Means of questionnaire administration and Focus group discussions were used to establish the perceptions and practices of community members with regards to the White Volta River, and traditional forms of WRM. The results of the study show that some community members perceive strong informal water rights held by traditional authorities in the areas of indigenous water permitting systems and conflict resolution mechanisms. Coping strategies evolved during extreme events of draughts and floods. Indigenous laws and/or practices as well as the bye products of Taboos resulted in the management and conservation of local water resources. Proposed strategies that could help incorporate IFWRM into formal systems include: Use traditional leaders to keep rec6rds with regard to every activity in or along the river banks through the issuance of water permits to small scale and peasant farmers; create awareness among indigenous communities on their past efforts in WRM and the need for more cooperation and participation from them and to adopt and implement the first most preferred indigenous forms of WRM identified in the various communities; provide alternative/sustainable livelihood supports to help reduce unsustainable evolving coping strategies to extreme environmental conditions along the river banks; create a subcommittee of the White Volta Basin Board (WVBB) on indigenous water rights and management forms to foster a more comprehensive implementation of Integrated Water Resources Management (IWRM) within the WVB. Keywords: Integrated Water Resources Management; Indigenous; Traditional; Water Resources Commission; White Volta River; Basin
- ItemPerformance of small reservoir irrigation schemes in the Upper East Region(2010-07-06) Sekyi-Annan, EphraimThe development of small reservoirs has been found to be a key contribution to reducing agricultural and water scarcity problems in semi-arid environments. It is therefore important that the performance of these small reservoir irrigation schemes be evaluated to keep track of whether or not the objectives are being achieved.
- ItemPerformance of evaluattion of AngloGold Wastewater Treatment Plant (PWTP) Obuasi Mine Ashanti Region(2010-07-07) Biney, Stephanie A.B.The study focused on the evaluation of the AngloGold wastewater treatment plant for the removal of Arsenic and Cyanide located at Sulphide Treatment Plant,(STP). The company's Tailings waste generated and discharged annually is estimated to be about 2,483,815 tons, they constitute about 80% of As and CN.
- ItemPublic perception of GWCL/AVRL water supply service delivery- case study; Kumasi- Ghana(2010-07-19) Babalola, EdwardThe research was carried out in the Kumasi Metropolis of Ghana to determine the perception of the public on the quality of water supply service delivery under the jurisdiction of Ghana Water Company Limited (GWCL) and Aqua Vitens Rand Limited (AVRL). A survey was carried out in three (3) out of eight (8) GWCL/AVRL districts in the Kumasi Metropolis using structured questionnaires.
- ItemAmbient air quality and the health of communities around Chirano Gold Mines Limited(2011) Ntim, MichaelIn communities where mining operations take place there are lot of environmental problems that comes with their processes. One of the greatly affected parts is ambient air quality. This studies aims at investigating the pollution status of the ambient air and the state of health of the communities living within its catchments. With the vitalograph, lung function tests namely; Forced Vital Capacity, Forced Expiratory Volume in 1 sec., Peak Expiratory Flow and Forced Expiratory Flow were performed on inhabitants of Paboase and Akoti communities in the concession of the Chirano Gold Mines Limited. The PM10 and Total Suspended Particles (TSP) in the ambient air were also monitored for a period of 8 months at 7 sampling stations. Results show that the mean PM10 level (64.04 μgm-3) was below the EPA- Ghana standard (70 μgm-3) but above the WHO standard (50 μgm-3). Also the levels of PM10 were below these standards except at all sampling stations except at the Rom Pad (166.72 μgm-3) possibly due to the crushing of rocks and its feeding into the processing plant causing greater liberation of particulate matter into the atmosphere. Mean TSP level (138.93 μgm-3) was also below both the EPA- Ghana standard (230 μgm-3) and WHO standard (200 μgm-3). For similar reasons, higher levels (367.62 μgm-3) than the standards were recorded at the Rom Pad. There was a statistical difference (p<0.00) between the predicted and the measured ling functions suggesting that the ambient air is not polluted and hence, there are health effects associated with the prevailing ambient air quality.
- ItemProductivity of Stored Water in Small Reservoirs for Dry Season Agriculture in the Upper East Region of Ghana(2011-08-11) Yamoah-Antwi, DwuodwoThe Upper East Region (UER) of Ghana is a water stressed area with the main occupation of the people being agriculture. The importance of small reservoirs for the sustenance of the livelihood of the people in this part of the country during the dry season cannot be over emphasized. Most of these small reservoirs were constructed, in the 1960s, mainly with the aim of providing water for domestic use and livestock watering during the dry periods of the year. Over the years, however, these small reservoirs have been put to a variety of uses such as irrigation and livestock watering, some of which accelerate the depletion of the stored water during the dry season, resulting in the reservoirs not being able to serve the purposes for which they were constructed. To address this situation, this study was conducted to determine the productivity of stored water in small reservoirs and to use this productivity values together with observations and interviews as a means of suggesting strategies for the improvement of water use so as to ensure water availability for the entire dry season period. Water productivity can be thought of as the output (product) that can be obtained per unit volume of water used or applied for either crop or livestock production. Data on crops and livestock were obtained through questionnaires administration, interviews, focus group discussions, physical measurements, official records as well as field observations from nine reservoirs in the UER. Results of the study showed that donkeys have the highest water productivity value of (GH¢ 290 /m3) followed by cattle (GH¢ 133 /m3). Sheep and goat both have productivity values of (GH¢ 18 /m3). Cattle and donkey have high water productivity values chiefly due to the variety of products and services they render. For crops, tomatoes have the highest productivity value of GH¢6.70 /m3 as opposed to leafy vegetables and pepper with productivity values of GH¢ 2.90 /m3 and GH¢ 1.40 /m3 respectively. Also productivity improvement strategies such as training of water user association (WUA) members, water conservation mechanisms, provision of standards for furrow formation and prevention of stored water from pollution were suggested based on the water productivities as well as physical measurements, interactions and observations made. Key words: Small Reservoir, Productivity, Stored water, Ghana
- ItemShort-Term Traffic Volume Prediction In Umts Networks: Validation of Kalman Filter-Based Model.(2012) Dorgbefu, Maxwell Jnr.Accurate traffic volume prediction in Universal Mobile Telecommunication System (UMTS) networks has become increasingly important because of its vital role in determining the Quality of Service (QoS) received by subscribers on these networks. This study explores traffic volume prediction and, adapts and validates the Kalman filter-based short-term traffic volume prediction model for UMTS networks. In this study, we adapt and validate the Kalman filter-based traffic volume prediction model which is used more in transportation engineering. The model was adapted based on two key assumptions that make it possible for us to characterize the short-term traffic volume patterns for UMTS networks to suit the Kalman filter algorithm. The model so adapted was carefully fine-tuned and implemented in MATLAB. The model was then validated with traffic volume data collected from a live 3G network using the graphical and r2 (coefficient of determination) approaches to model validation. The results indicate that the model performs very well as the predicted traffic volumes compare very closely with the observed traffic volumes on the graphs. The r2 approach resulted in r2 values in the range of 0.87 to 0.99 which compare very well with the observed traffic volumes. A little was done on sensitivity analysis of the model parameters, and this has been recommended for future research. The result obtained in this study brings out the fact that, the Kalman filter algorithm is very useful in predicting short-term traffic volumes for UMTS networks.
- ItemGeomechanical Characteristics of Natural and Stabilised Black Cotton Soils from the Accra Plains of Ghana(2012) Gidigasu, Solomon Senyo RobertBlack cotton soils or tropical black earths or black clays are potentially expansive soils which classify as vertisols in pedological parlance and have been found to occur in all major climatic zones of the world. These soils are considered ―problematic‖ and sometimes as ―potential natural hazard‖ because they are susceptible to seasonal volumetric changes, exhibit severe cracking when dry, swell and yield low bearing strengths when wet, etc. These problems cause extensive damage to light structures founded on them and estimated cost of damage due to expansive soils in general runs into billions of dollars annually. Considering the widespread prevalence of these soils and the problems they pose to structures founded on them, there is the need to conduct studies into the geological and geomechanical characteristics of the black cotton soils to enable effective utilization. Although some works have been done globally on these soils, these rather useful information are scattered in various publications. The need to collect these scattered information, synthesize them and present a hands-on-information regarding the nature, distribution, physical and engineering properties of the black cotton soils for the benefit of the construction industry has long been felt. Secondly, it has also become necessary to conduct studies with the view to enhancing knowledge on the geology and geomechanics of these soils. This study has attempted to address the above mentioned problems through a review of literature on the mode of formation, nature, as well as distribution of these soils around the world and secondly, presents studies on typical black cotton soils from the Accra plains of Ghana. Soil samples were collected from Tsopoli and Doryumu, both in the Accra plains of Ghana and subjected to physical, chemical and mineralogical as well as geomechanical studies. Results of the study reveal that the black cotton soils are formed over the Garnet-Amphibolites Gneisses of the Dahomeyan Supergroup. The chemical compositions of the soils indicate iii that the most abundant oxides are silica, alumina and iron oxide. The mineralogy of the two soils from X-Ray Diffraction analyses are similar and are composed of Quartz and montmorillonite. The geomechanical studies also suggest that the natural black cotton soils are unsuitable for subgrade construction and hence require improvement through stabilization. Attempts at stabilising the soils with quarry dust, pozzolana and pozzolana-cement which are readily available local materials, reveal that although the three stabilizing agents improved some geomechanical parameters of the soils the pozzolana-cement appears to be the most effective for stabilising the black cotton soils.
- ItemModeling Demand for a Telecommunication Utility Operator Based On the Box-Jenkins Methodology(2012-06-23) Botchey, Francis EffirimTelecommunication Demand Modeling has been a problem both in Ghana and the global world and has been under study for a long period of time. Developments in new communication technologies such as mobile devices and developments of new services to meet user demand such as video, multi-media and data services has led to an exponential growth in the demand for these services.In Ghana, the national regulator, the National Communications Authority puts cellular phone penetration in the country at about seventy percent (70%). The sharp increase in the number of customers over a short period and limited infrastructure has led users to raise concerns over the quality of service been offered. It is in this light that this thesis attempts to solve a case study of the telecommunication demand modeling for a leading cellular company in Ghana. Worldwide,different approaches have been employed in solving this very sensitive demand problem. The thesis employed the Box- Jenkins methodology to develop a near perfect ARIMA (2, 1, 0) model with the corresponding equation being that can adequately forecast the future rise in the subscriber base so that this can be carefully factored in planning so proper decisions can be taken to minimize this demand problem. With a mean absolute error of 8405 which is insignificant when considering the nation Ghana as a whole.
- ItemThe existence of the Chirano Gold Mine Limited and its effect on the livelihood of the Chirano Concession Area(2012-06-29) Darko, EricGhana is endowed with rich mineral resources e. g. gold, diamond, manganese and bauxite. Mining of minerals has triggered agitation by communities, who expect improved livelihoods from the mining companies. This study aimed at assessing the effect of the existence of the Chirano Gold mine Limited (CGML) on communities in its concessional area (Etwebo, Akoti and Paboase). Quantitative and qualitative primary data on general household characteristics e. g. employment, food security, health care, and sustainable utilization of natural resources were collected via questionnaire, interviews and personal observations. One hundred and fifty (150) respondents were drawn from traditional rulers, district assembly, land owners, farmers, youth groups, opinion leaders and women. The Statistical Package for Social Scientists was used to analyze the data for percentages, ranges and central tendencies. Results indicated that majority (98.2%) of respondents have obtained both direct and indirect employments (through stimulus for infrastructural development) from CGML. Thirty two (32%) of the respondents expressed worry about lose and degradation of farms, farm lands and farm roads while 93% cited the problem of air pollution. Sixty-four (64%) respondents have not been educated beyond the Junior High School. This placed restrictions on the extent of employment for members of the communities who on the contrary have not fully appreciated this limitation. There appears also to be a wide communication gap between CGML and the communities. This has masked the company’s image weakening its mutual co-existence with the communities. Adoption of more open communication and operational policies and stakeholder inclusion in local interventionary measures could help improve the relationship between company and the communities for co-existence.
- ItemTechnical and Economic Analysis of a 1mw Grid-Connected Solar Photovoltaic Power System at KNUST-Kumasi(2012-09-19) Kumi, Ebenezer NyarkoGrid-connected solar PV systems, though the fastest growing renewable energy technology in the world, have not been fully exploited in Africa; one of the reasons being the very high initial investment. Prices of solar PV systems have however been on a decline for the past few years due to technological innovations which have led to improvements in cell efficiencies and the economies of scale resulting from increase in production. The main purpose of this thesis is to present a technical and economic analysis of a 1MW grid-connected solar photovoltaic power system for the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi using rooftops of buildings on the campus. A solar resource assessment done to know the amount of solar radiation available at KNUST showed that KNUST receives about 4.30kWh/m2/day. A roof assessment which considered parameters such as the surface orientation and pitch of roofs, roof area and the possibility of shading of the roof, also revealed there is about 43,697m2 of roof space available for grid-connected solar PV installations. In technical analysis of the 1MWp solar PV system, the three (3) commonest solar PV module technologies were selected and their performance simulated using PVsyst software. Amorphous silicon modules were found to perform better than monocrystalline and polycrystalline modules over the one (1) year simulation period. The financial analysis carried out using RETScreen revealed that at a solar PV market price of US$4.45/Wp and a tariff of US$0.11/kWh (tariff paid for Asogli Power Plant which happens to be the most expensive generation source in the country), the project is not viable unless feed-in tariffs greater than US$0.43/kWh are paid.
- ItemThe effect of redials and retrials on the GSM Network(2012-12-16) Gyamfuaa, Mintah JenniferThe scarcity of spectral resources limits the number of channels that can be used on a telecommunication network. Consequently, a user requesting a service particularly a call may be blocked because all channels may be occupied. Initial planning and design of GSM network may not necessarily be accurate because all parameters including the traffic which determines the blocking of the network are based on estimations. Such networks may not meet the industry standard especially when it comes to blocking which is a measure of the Grade of Service (GoS) of the network. A user or the system may experience blocking at one time or the other. Both users and the network may attempt to get a connection. These reattempts constitute redials on the part of the user and retrials on the part of the network and they introduce a phenomenon which cannot be neglected in the analysis of a network. All of these retrials and redials are registered as separate calls. As a result, during the busy periods when blocking is observed in a cell, counters register a much larger volume than the effective call attempts. This research seeks to study of the effect of these reattempts on the GSM network. We seek to find how the blocking probability, redial probability, number of redials and the number of retrials affect the GoS of the network. Four analytical models namely Generalized Redial/Retrial Model (GRRM), Uniform Redial Model (URM), were applied to measured load to extract the excess load which comprise of redials and retrials. When the extraction is complete, the actual load that is supposed to be on the network would be obtained after which an efficient and a better network can be designed. The findings in this study revealed that network traffic is inflated with redials and retrials generated by networks subscribers and the network respectively. All the models when applied produced actual loads that were less than the measured loads. GRRM and SHM proved to be better models to use on highly congested networks while URM and IRM proved to be useful for all congestion conditions. It was also observed that an increase in the blocking probability and the redial probability introduced more load onto the network as the redials and retrials increase. The study has also shown that the network blocking probability may not always meet the industry standard and the number of channels that are used for network operations may often be inadequate.
- ItemIdentification of the Critical Points For Polycyclic Aromatic Hydrocarbon Contamination along the Cocoa Processing and Storage Chain in Ghana(2013-07-13) Kwaku Owusu, SebastianCocoa, a natural resource has shouldered the socio-economic life of Ghana through generation of employment and foreign exchange since its introduction into the country in 1815 by the Dutch Missionaries. Nonetheless, the industry faces some challenges; Exported cocoa has come under strict scrutiny due to elevation of the levels of a carcinogenic, mutagenic and an endocrine-disrupting compound termed polycyclic aromatic hydrocarbon (PAH). Although the general post-harvest handling of cocoa has received some level of attention, how critical the contributions of the specific primary processing and storage stages along the chain are and the level of knowledge of farmers on the causes and effect of PAH contamination are not known. These situations shield areas that need intense focus and are assessed by this study to help in designing policies and strategies for quality improvement. The concentrations of PAH in cocoa sampled from Ashanti, Brong-Ahafo, Central, Eastern, Western-North, Western-South and Volta regions (cocoa-regions) of Ghana were analyzed using the Gas-Chromatography Mass Spectrometer. Also interview via questionnaires were used to ascertain knowledge of farmers and other handlers including purchasing officials with regards to PAH level. Results indicate that cocoa beans processing involves pods gathering and opening, bean fermentation and drying. It was followed by bagging and storage before shipment. PAH concentration was higher in the shell than the nib (although < EU‟s threshold limit of 2ppb) and occurred during drying (0.925 ppb), depot storage (1.486 ppb) and shipment (1.842 ppb). Inappropriate practices e. g drying near fire and vehicle roadside which promote contact of beans with smoke, petroleum products e. g. oil, diesel and petrol could account for this situation. Lack of knowledge by cocoa farmers due mainly to low level of education was also established as a critical factor that requires greater attention.
- ItemGIS-Based flood prediction of the Black Volta in a climate change scenario. case study:the Dikpe catchment in the Lawra District of the Upper West Region(2013-08-15) Danquah, Twumasi YawUnderstanding the basic relationships between rainfall and runoff is vital for effective management of flood water. The Lawra District of the Upper West region (the driest region in Ghana) has experienced periodic and devastating flash flood resulting from high intensity short duration rainfall, a characteristics of semi-arid and arid regions...