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- ItemA Security Shield for Internet of Things (IoT) Devices(KNUST, 2019-06) Justice Owusu, AgyemangThe Internet of Things (IoT) is a new paradigm that enables the convergence of smart objects and the internet. It is an intelligent network that connects all things to the Internet for the purpose of exchanging information and communicating through the information sensing devices in accordance with agreed protocols. Aside the various benefits IoT provides, it also presents challenges related to security and privacy. The direct connection of IoT devices to the internet makes them susceptible to several security threats. Some ongoing projects for enhancing IoT security include methods for providing data confidentiality and authentication, access control within the IoT network, privacy and trust among users and things, and the enforcement of security and privacy policies. However, even with these mechanisms, IoT networks are vulnerable to multiple attacks aimed to disrupt the network. For this reason, another line of defense, designed for detecting attackers is needed. Intrusion Detection Systems (IDSs) fulfill this purpose. Previous resarch works propose IDSs in relation to IPv6 over Low-power Wireless Personal Area Network (6LoWPAN). However, since IoT will be used in many application domains with different technologies (WiFi, BLE, NFC and Z-Wave), development of IDSs only for 6LoWPAN is insufficient to meet the security needs of every IoT system. This research work focuses on IDSs for IoT devices that use WiFi technology. No previous works address IDSs for IoT devices that use WiFi technology. The research proposes lightweight intrusion detection algorithms that addresses ManIn-The-Middle (MITM) and Rogue Access Points (RAP) attacks. It goes further to propose an orchestration framework for IoT devices which can be used to logically isolate these devices in instances where vulnerabilities are found on them.
- 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.
- ItemAn Approach To Selectively Block Mobile Phone Communication Within A Mobile Phone Restricted Area(KNUST, 2019-06) Michael AgyareAbstract The use of mobile phone jammers to discourage mobile phone usage in mobile phone restricted areas has some limitations. One major limitation is that, once the jammer is activated no mobile phone can be able to function within the restricted area. For that reason, in the case of emergencies, no mobile phone can either make or receive phone calls or perform emergency calls (police, fire and ambulance services). Works done in literature can detect and block phone calls in a certain way but depends on the mobile switching centre in order to block communication in the restricted area. Therefore, in this thesis, a selective mobile phone communication blocking system is proposed which does not depend on the mobile switching centre in order to perform blocking of communication. The proposed system seeks to allow privilege users access to communication and block non-privilege users with respect to a specific user location. Some mobile phone user locations were considered in this thesis (Hospitals, Banks and Schools). A user from a particular user location cannot enjoy the same privileges at a different location provided that user is privileged. The selective blocking nature of the system was simulated using Fuzzy Inference System (FIS) toolbox (mamdani). The inference method is based on a set of IF-THEN rules and membership functions of the input variable and output variables of the system. Users for the different locations were converted into input triangular membership functions. The output is the decision (“allow” and “not allow”) for each of the inputs. S-shape and Z-shape membership functions were used as the output decision variables. The set of IF-THEN rules were used to link the input variables to the output variables. The fuzzy inference system was able to perform selective blocking of communication services for privileged and non-privileged users. The results in this work shows that when the proposed system is implemented mobile phone communication service can be prioritised to suit privilege users in specific mobile phone restricted areas.
- ItemAnalysis And Detection Of Traffic From DOS Attack Tools Using Data Mining(KNUST, 2019-10) Seth Djanie KoteyThere has been a significant increase in the use of the internet over the past 20 years. As of June 2019, it was estimated that the number of internet users worldwide was over 4.4 billion, corresponding to about 57% of the world’s population. The increase in the use and dependability of the internet has left in its trail a wide variety of vulnerabilities to defend against. One of the key security concepts that helps to guide cybersecurity policies is availability. In a computer network, a denial of service prevents users from having access to resources or services over the network. Denial of service (DoS) attacks are attacks purposely to disrupt availability of a network infrastructure. In past years, a DoS attack required a lot of skill and knowledge in networking for an attack to be launched. However, in recent years, DoS attack tools have been developed by various individuals and groups of people and are readily available on the internet for free or for a little amount of money. Such tools can be used by even the least skilled or knowledgeable attacker. This research therefore sought to develop a defence mechanism against these easy-to-use tools. Attack traffic was captured from some DoS tools and compared with benign traffic. Based on the differences between the attack traffic and benign traffic captured, a signature-based detection algorithm based on support vector machine (SVM) classifier was proposed. The algorithm was tested using the Snort IDS tool and the results were compared with some existing DoS defence schemes. Tests results from the algorithm showed the proposed defence mechanism had a high detection accuracy, low false positive rate and fast detection time.
- ItemAnalysis Of Lumbosacral Angle, Bio-Data And Their Relationship With Low Back Pain(KNUST, 2019-11) Opoku, EvelynMany researchers believe that lumbosacral angle is one parameter that is of importance in evaluating the possible etiology of lower or low back pain syndrome. There is paucity of data on the lumbosacral angle of the lumbosacral spine in Ghana and other African countries. Most of the data in use in research and medical practice are based on other races but there are anthropometric differences in races. Therefore, the study sought to bring out an empirical data on the pattern of low back pain (LBP) in relation to Lumbosacral Angle (LSA) in our study population and also investigate the association between LBP, LSA, age, gender and weight. Lateral views of the lumbosacral spine radiographs of 177 Ghanaian subjects from the St. John of God Hospital at Duayaw-Nkwanta were studied. The demographics and anthropometric measurements of the subjects such as age, gender and weight were recorded. The LSA was measured using the Ferguson‟s orthogonal method with the Micro Dicom Viewer software. The researcher employed the descriptive as well as the regressional survey. The findings from the study indicated that the population were dominated by females who constituted 70.1% of the study population as against males who also constituted 29.9%. In terms of age, majority of the participants were between the ages of 40 to 59 years as against the least that were between the ages of 0 to 19 years. The results showed that 41.8% of the sample did not have low back pain as against 58.2% who had low back pain. The mean LSA value for the normal controls was 14.5º with SD ± 1.32º. This can value can be recognised as the normal LSA for our population in from the study. A positive significant relationship was established between LSA and Low Back Pain. This simply means that an increase in LSA leads to 2.5 % increase in probability or risk of low back pain. Findings from the study showed that an increase in age leads to 41.8 % increase in the probability of having low back pain. Weight was found to positively correlate to low back pain. An increase in weight leads to 1.6% increase in the probable result of low back pain. This relationship was predicted to be significant. The study showed that there is a positive and significant relationship between LSA, age, weight and low back pain. The probability of pain of the lower back among males was also found to be 33.1% less than the probability that will be incurred by females and it is also not a significant relationship. In conclusion the mean angle values and variables may form the reference values for the Ghanaian population.
- ItemAssessing The Direct Economic Impact Of Vehicular Corrosion(KNUST, 2019-11) Kelvin Agyei', BaakoABSTRACT This research was conducted to document the direct economic impact of vehicular corrosion. The study was carried out in Suame, a suburb of the Kumasi Metropolis in the Ashanti region of Ghana. Commercial vans and saloon taxis were targeted for the study in twelve corrosion auto mechanic shops. Data was accumulated through a wellorganized semi-structured interviewing checklist given to masters of the work shop and the drivers of the vehicles interviewed. A total of sixty cases were recorded and analyzed using the statistical package for social scientist (SPSS) over a period of six months, with results presented in bar charts. The study revealed that the average direct cost of corrosion repairs was between GH₵100 - GH₵200 per each repair visit to the workshop. The most affected part of the vehicle was the running board, recording about 28.33%. Furthermore the most dominant form of corrosion was filiform corrosion which normally occurs under protective cover. The study further revealed that the major cause of corrosion was due to the maintenance culture of the vehicle owners.
- ItemAssessing The Impact of Septic Tanks on Groundwater Quality of selected communities around KNUST Campus(KNUST, 2019-10) Takal, Jeremiah KasalkuWater is an indispensable resource to mankind and life in general. Over the world, issues of water scarcity and quality are becoming pronounced with increasing global population, industrialization and urbanization. As a result, groundwater has become an important source of water supply throughout the world. The pressure on land and its resources in the study communities as they serve as residence for students, lecturers and the business community has impacted on groundwater quality. Small pieces of land acquired for building virtually does not give room for considering the siting of septic tanks and underground water. The quality of groundwater from eight boreholes/wells from Ayeduase, Boadi and Kotei in the Oforikrom Sub-Metro of the Ashanti Region were analyzed between February and July 2017. Water samples were collected from the eight boreholes/wells within the three communities and analyzed for temperature, pH, and some selected anions NO3- , SO2 -4 and Cland bacteriological parameters such as total coliform and faecal coliform. The GPS locations of other 54 boreholes and the closest septic tank were taken and the kriging interpolation was applied to extrapolate values of the measured parameters at these locations. The results from the analysis showed that pH of the water was slightly acidic (4.8 to 5.9). With the chemical parameters measured, all of them were within the WHO guidelines for drinking water, ranging from 11.7587 to 53.4723 mg/L, 0.00048 mg/l to 19.4753mg/l, and 4.22 to 40.32 mg/l for chlorides, sulfates and nitrates respectively. Both the total coliform and the faecal coliform levels were low, 0.07 CFU/100ml – 7.94 CFU/100ml for the total coliform count and 2.59 CFU/ml – 19.89 CFU/ml for the faecal coliform count. The research also measured the effect of septic tank-borehole/well distance on the variables measured. A regression analysis revealed that there was zero to weak correlation in all the parameters measured, with the “r” values as -0.02, -0.05, -0.04, 0.06, -0.09, 0.11 and -0.42 for total coliform, sulfate, pH, faecal coliform, nitrates and chlorides respectively.
- ItemAssessing the Water Supply Potential of Boreholes on Kwame Nkrumah University of Science and Technology Campus(2013-12-17) Boakye, Opoku RichardThere have been major expansions on the Kumasi water supply system all in the bid to meet the demand of its ever-growing population. However, many places in the metropolis still continue to experience interrupted water supply and Kwame Nkrumah University of Science and Technology (KNUST) even though it is a priority area, continues to experience water shortages. In a bid to cover these shortages, colleges, departments, hostels etc. have drilled boreholes to make up for the shortages. As a result, many boreholes are dotted over the university campus serving the needs of individual departments and hostels. This project seeks to assess the groundwater potential of KNUST to see if all the boreholes could be integrated into a system of water supply for the university community. Mapping of all boreholes (with coordinates and some characteristics such as yield and depth) on campus has been done. The daily water demand for the university has been estimated to be 3000 .The potential of all the boreholes drilled on campus has been assessed to be 2220 when pumping for 18 hours a day. The water quality of the water from the boreholes has been analysed and the results show that, there are no major health concerns from the existing boreholes in terms of iron, lead, manganese, arsenic and fluoride. However, total coliform was found to be present and the pH values show the water was slightly acidic and would pose some health risks to consumers. Therefore the water from the boreholes requires a limited amount of treatment in respect of disinfection and pH correction. Since the boreholes on the university campus have the potential of meeting about 74 % of the university’s total demand, it is recommended that a conscious effort be made to bring all the borehole water to a point where quality improvement can be done before its distribution to the whole university community.
- ItemAssessment Of Landuse Induced Land Surface Temperature Changes In The Greater Accra Region, Ghana(KNUST, 2019-08) Mathias AgbozoThis study explored the application of geospatial technology in understanding change pattern of Land use/Land cover (LULC) and associated Land Surface Temperature (LST) variability in the Greater Accra region between 1986 and 2018. Landsat satellite imagery between the months of December and February (dry season) were used for LULC analysis and LST Estimation. MODIS LST data for 1986, 2002 and 2018 were also utilized for the validation of satellite derived LST. The aim of this research was to investigate how LULC changes affects LST. The results of analysis show that LULC in Greater Accra region has changed significantly over the 32-year period. Four major LULC types identified were; vegetation, built-up, bare land and waterbody. Bare land cover type indicated decrease from 1986 to 2018 of 60.22%. Water bodies experienced varying trend of 7.84% decrease representing 9.11 Km2. Vegetation cover indicated 16.20% increase in 2002 and 28.02% decrease in 2018. This amounted to a total of 11.82% decrease in vegetation cover. On the contrary, built-up increased by 654.03% (724.3 Km2) between 1986 and 2018. LST was observed to have increased by 3.05 over the 32-year period of this study across the Greater Accra region. with the highest LST of 36.95 and the lowest of 20.19 , both recorded in 2002. The trend however indicated a significant increase between 1986 and 2002 but a decrease in LST from 2002 to 2018. The increasing trend in LST over time was found to be consistent with the observed urban expansion of the study area. High temperatures are also more apparent along the coastal belt of the region stretching northwards as development spread in the same direction. Total change in LST for the entire period of the study show increases of 3.53 , 3.04 , 2.78 and 2.65 for bare land, vegetation, built-up and waterbody land use/land cover types respectively. LULC association with LST shows that bare land experienced the highest negative change of 60.22% and this corresponded to the highest increase in LST of 3.53 over the same period. Correlation analysis and Coefficient of variation indicated largely that, MODIS LST data validated derived LST from Landsat satellite imagery. Trend of both LST values follow identical pattern with few instances where derived LST is greater than MODIS LST. Both NDBAI and NDBI exhibited a positive correlation with LST. NDVI demonstrated a negative linear correlation while NDWI indicated the strongest negative linear correlation with LST. Land use/Land cover change can be linked to rising Land Surface Temperature Changes in the Greater Accra region of Ghana. The research stresses the need to ensure effective land use planning by relevant regulatory bodies to control urban development and address anthropogenic causes of surface temperature changes.
- ItemAssessment Of Risk Priority Number Of 2.5 Mw Polycrystalline Silicon Photovoltaic Power Plant At Navrongo, Ghana In Sub-Sahara Africa.(KNUST, 2019-04) ALHASSAN SULLAIMANUnderstanding failures of photovoltaic (PV) modules is one key factor in enhancing the reliability and service lifetime of PV modules; and hence reducing the cost of PV systems and financial implications on investment. This study seeks to identify the field failures associated with installed PV modules in the Ghanaian climatic condition, which minimize the performance of modules, and pose reliability issues to the solar plants as well as financial implications to manufacturers and investors in the PV sector. Physical examination of the modules using visual inspection checklist and their corresponding electrical performance parameters (I-V characteristics) measurement using multimeter and I-V tracer were performed on two models of the five (5) year old 2.5 MW PV power plant at Navrongo. A MatLab program was used to evaluate the failures and degradation modes of 144 Polycrystalline silicon (Poly-Si) framed modules under the hot dry climate of Navrongo. The program is a statistical reliability tool that uses Risk Priority Number (RPN) to determine the dominant failures by means of ranking and prioritizing the failure modes. The visual inspection revealed front glass slightly soiled, junction box lid fell off, cell interconnect discoloration and backsheet crack between cells as the peculiar failure issues either affecting the performance of the modules and/ or posing safety concern to personnel and properties on site. Mean degradation rates of 1.11%/year and 1.23%/year were respectively computed for Model A (Jinko solar) and Model B (Suntech technologies) types of modules for the power plant studied. These degradation rates values are beyond the standard warranty limit of 1.0%/year reported in literature. In addition, short circuit current (Isc) and fill factor (FF) were determined as the dominant I-V parameters affecting the power degradation rates of the Model A and Model B modules respectively. The study also determined the total Global RPN value of 606 for the Model A type of modules for this plant, whereas that for Model B is 583. These RPN values fall within the reported values ranging from 500 to 755 in literature. With this information, investors can have an insight on the worth of a PV Plant and viability of their investment before making a decision. From this study, it can be concluded that, the five years old PV plant in operation is not performing very well and needs urgent attention to avoid loss based on the degradation rates of the fielded modules.
- 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.
- ItemCharacteristics of soil physical properties for pond design for aquaculture among rice farmers at Kwabre District(2015-03-17) Yeboah, Asare BarfourAgriculture, the backbone of the Ghanaian economy employs around 51% of Ghana's work force. Currently most younger farmers are quitting and moving to urban centers for other forms of employments because they claim it is not lucrative..............
- ItemClimate Change and Its Impacts on Flooding In Accra-Greater Accra Metropolitan Assembly(2013-12-16) Sanquah, Isaac OdoiClimate change resulting in high precipitation is of utmost importance as it yields floods of varied amounts. Such floods result in loss of lives and properties worth billions of Ghana Cedis (BGH₵). Accra, the capital city of Ghana, has experienced various levels of floods with the July 1995 incidence recorded as the highest floods over the basin. This research work seeks to investigate the impacts of floods over Accra basin as the future experiences changes in the climate system. Aptitude to predict future precipitations depends on established climate scenarios. Landuse characteristics and atmospheric parameters define the changes in the hydrologic cycle hence the resultant precipitations. This affects the variations in the precipitation pattern as the years proceed. Known precipitation values are used to develop flood vulnerability maps and their impacts due to changes in the precipitations assessed under each of the scenarios in an ARCGIS model for this work. Six main scenarios are developed based on the landuse characteristics of the basin. These are HISTORICAL_1995, SDAN_2020, SDOK_2040, SDIK_2060, SDIOL_2080 and SDIOK_2100 yielding precipitation values of 249.30mm, 234.09mm, 149.58mm, 24.93mm, 124.65mm and 398.88mm respectively. These precipitation values are integrated into the HYDROCAD software to generate runoff depths or flood levels, flood volumes and hydrographs for each of the sub basins within GAMA. Vulnerability assessment depends on known precipitation data; hence the historical_1995 precipitation used to develop the flood vulnerability map of Accra as the reference point for impact assessment. Climate change impacts on floods are then assessed based on the obtained precipitation values under each of the generated scenarios. Therefore, the developed climate scenarios helped to forecast precipitation values over the GAMA basin and assess their future impacts on floods. This will serve as an urban planning tool for the Government of Ghana (GoG) and other flood disaster management agencies.
- ItemConvergence Analysis of Massive MIMO Antenna Arrays Using a Geometry-Based Stochastic Channel Model(KNUST, 2019-10) Patrick DanourIn order to reap the full benefits of massive MIMO, the Base Station (BS) antennas must be significantly large to converge to favorable propagation condition or attain convergence (the state where the effect of noise and fast fading vanishes). However, increasing BS antennas results in closely spaced antenna elements which inadvertently leads to the detrimental effects of Spatial Correlation (SC) and that can affect the convergence of Massive MIMO System. So far, research works on Convergence have been investigated using Correlation-based Stochastic (CBSCM) channel models, which does not reflect accurate massive MIMO channel. This channel model does not take into consideration channel parameters such as the Pathloss, power delay profile as well as the characteristics of the antenna array needed for the practical massive MIMO system implementation. Therefore analysis of massive MIMO convergence regarding the Geometry-Based Stochastic Channel model (GBSCM), which reflects real practical massive MIMO channel and the effects of SC is needed. In this thesis, the convergence of massive MIMO based on GBSCM is studied. The effect of 3D SC of uniform rectangular and cylindrical array (URA and CA) based on the Maximum Power of Arrival (MPA) is incorporated. In the analysis, the Diagonal Dominance and Mean Absolute Deviation convergence metrics, were considered to study the effects of the SC on the asymptotic behavior of the channel matrix. The results support existing development that, increase in azimuth and elevation spreads of the angular distributions of arrival and antenna element spacing reduces the SC and thereby increases convergence rate of massive MIMO. Results also show poor performance for the Laplacian and Von Misses distributions in GBSCM, even for higher AS and ES, and angular spreads. Further it was realized that, in GBSCM, the convergence of massive MIMO was sensitive to antenna array topology regarding Gaussian and Student’s t-distributions. This contradicts previously established results that convergence is insensitive to antenna topology in CBSCM.
- 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.
- ItemCrash predictions model for two-lane rural highways in the Ashanti Region of Ghana(2015-03-23) Ackaah, WilliamCrash Predictions Models(CPMSs) have been used elsewhere as a useful tool by road Engineers and Planners. There is however no study on the predictions of road traffic crashes on rural highways in Ghana..............
- ItemDevelopment And Evaluation Of A Double Row Disc Ridger For Root And Tuber Crop Production(KNUST, 2019-10) David Amidu, WandusimABSTRACT The introduction of mechanical harvesters has been a breakthrough in root and tuber crop cultivation as it has greatly reduced drudgery with a potential increase in global cassava production. However, the use of these equipment requires line or ridgeplanting. While ridging is preferred and can be done manually, empirical evidence suggests that manual ridging is laborious, time-consuming and the quality and standard of ridging cannot be guaranteed. The objective of this study was to develop and test the performance of a double-row disc ridger for root and tuber crop cultivation. Functional analysis (FA) and computer-aided design methodologies (CAD) were applied. The device was fabricated from locally available materials and tools, making it an adaptable, resilient and affordable technology for small-scale farmers. The prototype was tested at varied tractor speed ranging from 1.67 – 2.5 m/s (6 – 9 km/h) and disc angle from 40o - 45o to determine the draught force, fuel consumption, wheel-slip, depth and width of cut. Preliminary results indicate that optimum performance was achieved at disc and tilt angle of 42.5o and 25o and tractor speed of 2.23 m/s (8 km/h). The ridger recorded a field capacity of 1.45 ha/h and average fuel consumption of 6.3 l/ha (9.14 l/h). It was observed that increased tractor speed and disc angle resulted in increased draught force from 1.8 – 2.4 kN, increased fuel consumption from 5.2 – 7.04 l/ha (7.81 – 10.45 l/h) and increased depth and width of cut from 30 – 40 cm and 250 – 280 cm, respectively. A hazard and operability (HAZOP) study established possible deviations, causes, consequences, safeguards, and recommendations for users. Further research is necessary to establish the effect of different moisture content and soil type on the performance of the ridger. Wear and durability test on different agro-ecologies are also recommended.
- ItemDynamic Bandwith Utitlization in Software Defined-Based Campus Networks(KNUST, 2019-11) Kobby Asare,ObengThe efficient utilization of bandwidth in campus networks is a major traffic engineering issue. It requires a complete knowledge of the underlying physical network architecture as well a means to automate or reactively and proactively program the network. The static nature of traditional network creates a hurdle that must be overcome to achieve the above. The Software Defined Network architecture proposes a novel way to automate, program and dynamically configure computer networks. This work uses the VMware virtualization software and the GNS3 network emulator to convert a traditional campus network into a Software Defined-based campus network. A data plane made up of software-based replicas of network devices is designed and configured to connect to a controller software. A network application scheme is implemented by leveraging the Hierarchical Token Bucket Queuing Discipline which automatically programs bandwidth allocation at the data plane through the controller based on traffic demands. The functionality of the architecture is tested by carrying out a number of parallel-connections to simulate changing traffic patterns. This is done using the Iperf Application. The results show the conversion of a traditional campus network into a Software Defined-based campus network. It also depicts the complete emulation of the entire Software Defined-based campus network. At the data plane of the emulated network, devices are able to forward packets to one another with the most active port forwarding about 9,000 packets. The controller obtains a global of all 11-network devices in the emulated network. The latency between the controller and the software defined switches at the data plane ranges between 50 and 62.5 milliseconds. The throughput between the controller and the software defined switches at the plane ranges between 2 and 9 Mbps. Application Plane to Control Plane communication in the emulated network is executed in an average of 30 milliseconds and bandwidth utilization occurs in a minimum of 11seconds and peaks at 27.5 seconds. It however becomes steady at 17 seconds as traffic patterns vary
- 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.
- ItemEngineering geological evaluation of Mfensi and Afari clay deposits for liner applications in municipal solid waste containment systems(2015-11-04) Endene, Che EmmanuelMfensi and Afari clay deposits in the Ashanti region of Ghana, have been the subject of considerable research works mainly for pottery, brick and tile, pozzolana, refractory productions, etc, but very little is known about their application as liner materials. This study therefore sought to evaluate the suitability of the two clay deposits as liner materials in municipal waste containment systems. Samples were collected from the sites and subjected to physical, chemical, physico-chemical, mineralogical, geotechnical as well as thermal analyses. Results of the study reveal that; physically, both clays were soft and had high water contents. Afari clay was yellowish in colour while Mfensi clay was greenish-grey in colour. The chemical compositions of the clays were analogous although their concentrations varied. The oxides of silicon, aluminum and iron together constitute about 90% and 80% in Mfensi and Afari clay respectively. The mineralogical compositions of both clays were similar and made up of quartz, kaolinite and magnetite. The cation exchange capacities of the clays were 32.33 meq/100g for Afari clay and 7.79 meq/100g for Mfensi clay. The clays were fine grained, with fines contents of approximately 64% and 88% for Afari and Mfensi clays respectively. Texturally, both clays classify as clay loam. The Atterberg limit tests gave the liquid limits and plasticity indices of both clays to be 64.78% and 40.52% for Afari clay and 42.85% and 22.43% for Mfensi clay respectively. The unconfined compressive strength of the Afari clay was 244.53KPa and that of Mfensi clay was 331.73KPa. The hydraulic conductivities of the clays were found to be of the order ×〖 10〗^(-7) cm/s. The average thermal conductivities of the clays were 0.025W/moC for Afari clay and 0.215W/moC for Mfensi clay. The use of leachate led to an increase in the plasticity indices and liquid limits of both clays with a reduction in the plastic limits. Reductions in the permeability’s of both clays were also observed when permeated with leachate. From the modeling, Afari clay had a higher flow rate and a lower breakthrough time relative to Mfensi clay. It is concluded that, Mfensi clay has a better anti-leakage behavior, higher breakthrough time and lower flow rate relative to Afari clay. Based on parametric analyses from the simulation with varying leachate head, leachate density and liner thickness, it was found that, the breakthrough times of both clays did not change when varying the leachate head while the flow rate changed with varying leachate head. Also, the breakthrough times and flow rates of the clays changed with varying liner thickness. Finally, the variation in leachate density resulted to a change in the breakthrough times for both clays and had no effect on the flow rates. From the overall study, the clays generally passed the requirement for use as liner materials in municipal solid waste landfills and hence they could be used for liner applications