ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT <p align="justify">The Arid Zone Journal of Engineering, Technology and Environment is peer reviewed journal with the objectives to explore, develop and elucidate the knowledge of Engineering design and technology, to keep Practitioners and Researchers informed on current issues and best practices, as well as serving as a platform for the exchange of ideas, knowledge and expertise among technology researchers and practitioners. AZOJETE is published by the Faculty of Engineering, University of Maiduguri, Nigeria.</p> <p><strong>p-ISSN:</strong> 1596-2490 | <strong>e-ISSN:</strong> 2545-5818</p> <p><strong>PUBLICATIONS:</strong> MARCH, JUNE, SEPTEMBER AND DECEMBER</p> <p>AZOJETE is currently indexed in the following indexing platforms</p> <p><a href=";hl=en&amp;authuser=1" target="_blank" rel="noopener">GoogleScholar</a>, <a href="" target="_blank" rel="noopener">DOAJ</a>, <a href="" target="_blank" rel="noopener">ACADEMIA</a>, <a href="" target="_blank" rel="noopener">ResearchBib</a>, <a href="" target="_blank" rel="noopener">CosmosIF</a>, <a href="" target="_blank" rel="noopener">CiteFactor</a>, &nbsp;Bielefeld University Library, IIJIF, SIS, Cosmos Impact Factor, <a href=";subAction=subjects&amp;publisherID=34&amp;journalID=38287&amp;pageb=1&amp;userQueryID=&amp;sort=&amp;local_page=&amp;sorType=&amp;sorCol=" target="_blank" rel="noopener">JournalTOCs</a>, <a href="" target="_blank" rel="noopener">OAJI</a>,&nbsp; Journal Factor, SPARC Indexing, <a href="" target="_blank" rel="noopener">OpenAIRE</a>, Eurasian Scientific Journal Index, Electronic Journals Library, ISI, Social Science Research Centre Berlin, <a href="" target="_blank" rel="noopener">WorldCat</a>, International Institute of Organized Research (I2OR), StudyLIB,&nbsp; Journal Finder, <a href="" target="_blank" rel="noopener">University of Saskatchewan Library</a>,&nbsp; ScopeMed, Microsoft Academic, <a href=";recordsPage=2" target="_blank" rel="noopener">PKP Index</a>, <a href="" target="_blank" rel="noopener">efita</a>, JournalFinder, <a href="" target="_blank" rel="noopener">Publons</a>, <a href="" target="_blank" rel="noopener">Ghent University Library</a>, University Library of Regensburg, University of Groningen Library, University of Georgia, Berkeley Library University of California, ProQuest, <a href="" target="_blank" rel="noopener">ISSN Portal</a>, <a href="" target="_blank" rel="noopener">PIST</a>, <a href="" target="_blank" rel="noopener">DRJI</a>, <a href="" target="_blank" rel="noopener">TEEAL</a>, <a href="" target="_blank" rel="noopener">Technical University of Braunschweig</a>, <a href=";View=uba&amp;Language=de" target="_blank" rel="noopener">University Library Augsburg.</a> <a href="" target="_blank" rel="noopener">The Leipzig University Library,</a> <a href=";context=L&amp;vid=44HYG_INST:44HYG_VU1&amp;lang=en&amp;search_scope=MyInst_and_CI&amp;adaptor=Local%20Search%20Engine&amp;tab=Everything&amp;query=sub,exact,Agricultural%20Engineering%20,AND&amp;mode=advanced" target="_blank" rel="noopener">London School of Hygiene and Tropical Medicine</a>, <a href="" target="_blank" rel="noopener">EuroPub DASJ</a>, <a href="" target="_blank" rel="noopener">SJIF</a>, <a href="" target="_blank" rel="noopener">Technical University of Braunschweig</a>, <a href="" target="_blank" rel="noopener">EuroPub</a>, <a href=";R=3747465" target="_blank" rel="noopener">Toronto Public Library</a>, <a href="" target="_blank" rel="noopener">EDUINDEX Index of Education</a></p> en-US <p>Copyright of the paper named above is hereby assigned and transferred to the Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria.</p> (Prof. N.A. Aviara) (Engr. S.K. Oyeniyi) Wed, 01 Sep 2021 00:00:00 -0400 OJS 60 Infiltration capacity of compacted lime treated black cotton soil as hydraulic barrier material <table> <tbody> <tr> <td> <p><em>Studies have shown the effect of hydraulic barriers in the reduction in movement of leachates, that have the potential of contaminating groundwater. Laboratory tests were conducted on black cotton soil treated with up to 5% lime by dry weight to assess its suitability in waste containment facilities. The test samples were subjected to particle size distribution analysis, consistency limit tests, compaction and hydraulic conductivity. The compaction energy of British Standard Light (BSL) was employed. The study showed decrease in liquid limit from 65.20% to 56.30% and plasticity index from 41.50% to 28.58% while plastic limit increased from 23.70% to 27.72% with the increase lime content.&nbsp; Maximum Dry Density (MDD) increases with increased in lime from 1.78&nbsp; to 1.88 g/cm<sup>3</sup> whereas the Optimum Moisture Content (OMC) decreased from 19.79% to 15.39%. Hydraulic conductivity of black cotton soil treated with percentage of lime content 0%, 1%, 3% and 5% of the soil weight examined for a period of 28days. The hydraulic conductivity value of natural soil was 1.65E-08 and decreased to 3.71 E-09 m/s at 5% lime content. Therefore, it is clear that hydraulic conductivity decreases with percentage increase in lime content. It is recommended that volumetric shrinkage, free swell and unconfined compressive strength should be carried out.</em></p> </td> </tr> </tbody> </table> A. N. Alkali, I. M. Shettima, B. B. Kurna , N. Y. Okunade Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Development of a windmill for pumping water using positive displacement pump <p><em>The abundant renewable energy sources have not been harnessed&nbsp; for electricity and other uses to date. Wind speed is high in the Northern part of Nigeria and therefore require utilization so as to reduce the use of harmful non-renewable energy sources. In this work wind energy was used to drive a windmills that provide mechanical energy directly for a borehole with a positive displacement pump with a 2.5ft stroke. The design analysis of the wind mill was carried out numerically based on the wind data collected. The proposed design were fabricated using designed dimensions. The rotary motion of the shaft were converted to a linear motion using slider-crank mechanism. The designed horizontal axis windmill has 3 blades has three blades driving the shaft. Also the kinematic modelling of the mechanism was carried out. The assembled windmill was tested and was found to have an operated efficiency of 58.2%.</em></p> <p>&nbsp;</p> B. Alkali, B. S. Elkanah, S. G. Amarem, A. B. Hassan, N. S. Gukop, E. A. P. Egbe Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Solid Waste Generation and Characterization in Ilorin, Nigeria <p><em>Global per capita waste generation rates and characterization vary by regions, countries, and within cities. The generation, l and characterization of waste from selected areas in Ilorin, Nigeria, prone to indiscriminate disposal of solid waste without consequence were analyzed for proper management. Municipal solid wastes were sorted, analyzed by weight and percentage composition using the quantitative approach. The average generated waste per capita was estimated to be&nbsp; 0.66 kg/day, w/w distribution was 57.53% food waste, 9.07% nylon (flexible films), 5.98% plastic (rigid containers),4.95% textile, 10.51% paper and 11.96% others. The average moisture content was 46.16% food waste, 20.63% nylon, 18.65% plastic, 36.67% textile, 18.45% paper and 42.89% others. The results show an average bulk density of 10.36 Kg/m<sup>3</sup> of food waste,&nbsp; 2.14 of nylon, 0.5 of plastic; 0.93 of textile; 2.74 of paper and others 5.36. The chemical analysis showed that volatile matter ranged from 20.55 to 24.10%, ash content 3.10to 3.90%, fixed carbon 7.5to 9.8%, calorific value 14820to 18360 (kJ/kg), nitrogen 0.40to 0.50%, hydrogen 4.38to 5.80%, carbon 40.90 to 44.30%, oxygen 30.80 to 34.60%, Sulphur 0.19 to 0.24%, fusing point of ash 3.12to 4.38 °C, and heating value from 13.520to 13.64 KJ/Kg. The results generated could play a positive role in the&nbsp; management of solid waste in that area.</em></p> <p>&nbsp;</p> O. A. Mokuolu, J. O. Iji, S. A. Aremu Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Development of an improved acm scheme for mitigating earth-to-space propagation effects <table> <tbody> <tr> <td> <p><em>In satellite communications, the communication link experiences propagation losses such as: Path loss, atmospheric losses, rain fading, ionosphere effects (such as scintillation), and other effects which can greatly affect the received signal strength and close the link budget in the worst case. The design of future broadband satellite systems has to be done with the challenge of more complex traffic mix and these harsher propagation conditions which mitigate the performance of the communications link. Link adaptation (LA) has been used in satellite communications applications for evaluating the performance of an adaptive modulation system in the unique space-based propagation environment. Despite the current research on improving satellite system performance, there is still a need to further develop a scheme that mitigates the effect of atmospheric impairments. This work develops an improved adaptive coding and modulation scheme that mitigates earth-to-space propagation effects. The scheme targets maximizing data throughput while staying below a Bit Error Rate (BER) threshold so as to successfully mitigate link impairment in fixed communication systems. Simulation of the work is carried out using MATLAB 2016b and System Toolkit (STK) 11.3. Simulation result showed that the iACM scheme was able to reduce the effect of path loss in time by 5% over the ACM scheme and also reduced the effect of path loss with respect to the angle of elevation by 2% over the ACM scheme and improvement in the network energy to noise ratio by 22.74% over ACM. In terms of system throughput, the iACM scheme showed an improvement in throughput by 24% over the ACM scheme. Finally, the iACM scheme has shown better performance in terms of throughput and thus, improve the performance of satellite communication.</em></p> </td> </tr> </tbody> </table> <p><br><br></p> A. M. S. Tekanyi, R. M. Idris, A. D. Usman, Z. M. Abdullahi , E. E. Agbon Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Influence of energy recovery system on the energy efficiency of a flat-bed dryer in the drying of turmeric <p><em>Drying is one of the most energy intensive unit operations in agricultural and food processing industry. Energy costs represent a major fraction of cost of operation of a mechanical dryer, therefore, the more efficient a dryer uses its energy supply, the lesser its cost of operation and the better it impacts on profitability of drying process. A flat-bed dryer of 25kg capacity was developed and fitted with air-to-air indirect mixing heat exchanger (Heat Recovery Unit, HRU) at the vent of the drying chamber. The dryer was tested to determine the impact of exhaust vent waste heat recovery on its energy efficiency and cost of operation. Turmeric, an important spice crop was dried at three temperatures of 60°C, 65°C, and 70°C under two operating conditions; (i) without HRU (C-I) and (ii) with HRU (C-II). The result show thermal efficiency, at C-I it was found to be 28%, 27% and 27% at 60°C, 65°C and 70°C respectively and for C-II it was 42%, 42%, and 40% at 60°C, 65°C, and 70°C respectively. This indicates that&nbsp; the overall thermal efficiency was improved by 15% for C-II at 65°C as compared to C-I at 65°C. ANOVA show there is significant different (P&lt; 0.05) between C-II and C-I as regards thermal efficiency. The result also showed that specific energy consumption was reduced for all drying temperatures levels of C-II as compared to C-I and the result shows that testing condition C-II, at 65°C has the lowest specific energy consumption of 1.79(kWh/kg) while C-I at 60°C has the highest value; 2.37 (kWh/kg), this showed significant different (P&lt; 0.05).Drying curves of turmeric were plotted and it was found that C-II performed better in drying turmeric since the moisture lose was faster than in C-I and the drying time was lowered by 4hrs for C-II at 65°C compared to C-I 65°C. The average Return on Investment (ROI) of HRU was calculated considering average of 260 working days or 130 batch drying operation per annum with one drying cycle per two working days and was found to be 0.61 and the payback period was 19 months. It was concluded that the developed flatbed dryer can be used to dry 25 kg of turmeric per batch in 25 hours drying time using operating condition C-II, 65°C which showed better quality in terms of energy efficiency and drying rate.</em></p> <p>&nbsp;</p> E. A. Adu, T. Pandiarajan, W. Farzana, K. A. K. Abba Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Mathematical prediction of nitrogen and phosphorus removal from piggery wastewater by horizontal sub-surface flow constructed wetland. <p><em>Mathematical equations were derived for estimation of nitrogen and phosphorus removal from piggery wastewater in horizontal subsurface flow constructed wetlands. The model inputs included wastewater inflow, retention, plant uptake and nutrient loss to the atmosphere by volatilization of nitrogen. Plant die off, precipitation and exchange with subsurface were considered negligible. The calibration and validation of the model was carried using different sets of experimental data generated from a pilot constructed wetland monitored over a period of seven months. The results show that the amount of nitrogen and phosphorus concentrations decreased exponentially within three days of retention in the wetland and, thereafter, the reduction appeared constant over higher retention time subject to the decay coefficient. There was high correlation between the simulated and observed parameters with R2 = 0.9537 for nitrogen and 0.9912 for phosphorus respectively. The low values of the mean bias error (ME) of 0.211 and 0.139, root mean square error (RMSE) of 0.32 and 0.18, and relative error of RE of 24 and 12%, demonstrated the ability of the model to predict nutrient removal accurately. The models efficiencies of 84 and 77% and index of agreements of 0.6527 and 0.8676 for nitrogen and phosphorus respectively, indicate an acceptable level of the models predictive capacities. The linear regression coefficients appear reasonable given that the system was a natural system located in the field, where uncontrolled influencing factors could weaken optimal performance. Because of challenges associated with Scaling-up this result.&nbsp; longer field studies are recommended. The models developed in this study considered the features of horizontal-subsurface-flow constructed-wetlands for removal of nitrogen and phosphorus from piggery wastewater. The high correlation between the developed models and the calibrated parameters showed that they are rational. The models can be used to simulate nitrogen and phosphorus removal in horizontal-subsurface-flow constructed-wetlands. The performance of these models meets the water quality discharge or reuse standards of Nigeria for wastewater discharge to land and surface water.</em></p> <p>&nbsp;</p> I. J. Udom Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Factors Affecting Time Performance of Tertiary Education Trust Fund Construction Projects in North-East, Nigeria <p><em>Higher education institutions in Nigeria faced with the challenges of inadequate funding for the provision of facilities and rehabilitation of decaying ones. To address this issue, the Tertiary Education Trust Fund (TETfund) was established. However, it has been reported that, there are poor time performance of TETFund projects in tertiary institutions in Nigeria. This study was conducted to determine factors affecting time performance of Tertiary Education Trust Fund construction projects in north-east, Nigeria. Thirty-two (32) factors causing delay in construction projects were identified from the literature review. Data collection was carried out by means of survey questionnaire. One hundred and thirty-six questionnaires (136) were shared among construction professionals comprising of clients, contractors and consultants, 112 were returned completed representing 82% response rate. The data collected were analysed by means of frequency, severity index and Spearman’s rank correlation. The results obtained revealed that, the most common delay factor in TETFund construction projects according to the three categories of the respondents is late procurement of materials. Similarly, there is consensus among the three categories of the respondents that type of project bidding and award is one of the most severe delay factors in TETFund projects. Clients and consultants pointed out that, factors with high impacts on time performance include ineffective planning and scheduling of project by contractor, poor site management and supervision by contractor, and shortage of qualified workers. Whereas, based on contractors’ views, delay in progress payments by client has the highest impact. The study recommended that adequate planning and scheduling for all activities of project should be done by contractors at an appropriate time. The findings of this study can assist TETFund construction project team members to understanding factors that can significantly affect timely delivery of their projects.</em></p> M. M. Mukhtar, D. Abdussalam, M. M. Mustapha Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Modelling Self Purification of River Benue within Makurdi. <p><em>This study considered biochemical oxygen demand (BOD), dissolved oxygen (DO), the re- oxygenation rate, the de-oxygenation rate, the self-purification rate model for River Benue within Makurdi reach. The hydrodynamic data were collected while re-oxygenation rate, de-oxygenation rate and self purification rate were calculated using DO and BOD at 14 different stations along the river stretch. An empirical model for self purification was generated analytically using multiple linear regression equation analysis. The pH varied from 6.8 to 8.08 while DO concentration between 4.0 mg/L and 6.3 mg/L; BOD concentration ranges from 1.0 mg/L to 2.0 mg/L; Mean re-oxygenation rate of 0.179 in the raining season and 0.1 in the dry season; Mean de-oxygenation rate of 0.1186 day-1 in the raining season and 0.1345 day-1in the dry season was calculated; Self purification coefficient had a mean value of 1.3398 in dry season and 0.8354 in rainy season;&nbsp; The model has coefficient of determination (R2) and adjusted R2 of 0.5691 and 0.5469 respectively; a multiple correlation coefficient of 0.7544 and root mean squared error of 0.2433 between the observed field data and the model data. In conclusion, the river has good self purification ability and the model generated is reliable considering the root mean squared error.</em></p> I. M. Aho, G. D. Akpen , C. C. Aniakor Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Cranfield University and University of Maiduguri CubeSat (CUUMcube) for Technology Demonstration: Baseline and Mission Design <table> <tbody> <tr> <td> <p><em>CubeSats are small satellites that can be deployed to orbit to achieve various space mission goals. Lately, there are several CubeSat launch opportunities from the International Space Station (ISS). For University of Maiduguri to be able to bid for such launch opportunities there is a need for a baseline for a spacecraft and a mission design. Thus, this paper using the Systems Engineering approach is a baseline and mission design for a CubeSat using CubeSat COTS (commercial off-the-shelf) components targeting the KiboCUBE opportunity. CUUMcube mission is a technology demonstration mission to fly two payloads, Cranfield’s Acoustic Sensor and De-Orbit Mechanism (DOM). The Acoustic Sensor is a microphone that measures vibrations, it is intended to measure vibrations due to: spacecraft thermal cycling mechanical noise, antenna deployment, Micrometeoroids and Orbital Debris (MMOD) impacts, DOM deployment and changes in acoustic response of spacecraft after deployment of both mechanisms. The DOM is a deployable drag sail, a passive method of removing spacecraft from orbit afterlife in the effort of mitigating space debris.</em></p> <p><em>Thus, mission baseline reached after the design is to deploy a 1U CubeSat, to carry two payloads (Cranfield’s Acoustic Sensor and DOM), using COTS components. The deployment of the spacecraft will be from the ISS into an elliptical orbit (perigee: 380km, apogee: 420 km).</em></p> </td> </tr> </tbody> </table> <p><em>The ground control stations are COTS component too, where there will be one each in UK and Nigeria. Lastly, 30 mins after deployment into orbit the mission sequence starts from the activation of spacecraft to 24 hours recording mode to monitoring mode by the acoustic sensor to capturing of vibrations. Hence, the antenna and the DOM will be deployed. The DOM will speed the orbit decay of the spacecraft, as a result it will speed the re-entry phase and burn in the process.</em></p> M. I. Ishaq, R. A. Kyari, I. Halliru, C. N. Amulah Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Propagation Loss Determination of GSM Signal Strength in Selected Buildings in Ilorin, Nigeria <table> <tbody> <tr> <td> <p><em>GSM signal building penetration loss is a problem often encountered by subscribers inside a building. As a result of building penetration loss, poor reception and signal outages often occur in many indoor locations and this accounts for increased attenuation of received signal strength of a cellular network signal when a subscriber with a mobile phone moves from outdoor to indoor. The study assessed the GSM signal penetration loss in thatched, wooden, block, mud and zinc buildings. Three network providers named A, B and C was used for the experiment. A low budget but very effective equipment (Two Tecno Pouvoir 3 plus Android phone) was used as the measurement tool. It was loaded with Network Signal Info application developed by KAIBITS Software GmbH installed software and positioned inside and outside the building to record indoor and outdoor GSM signal strength respectively for the three service providers in Ilorin, Nigeria. The results were then analyzed in order to determine and compare the path loss introduced by each of the selected buildings. This process was repeated for all the selected buildings, and the measurement was carried out for 6 months. The findings revealed that the outdoor signal strength was higher than the indoor signal strength for all the selected buildings; it also revealed that penetration loss is likely to be a function of the material used in the construction of the buildings. Zinc building has the highest penetration loss of 12.0dBm and thatched building has the least penetration loss of 2.6dBm. Information from this research will assist in selection of building materials for good indoor cellular network signal reception. It will also assist cellular network service providers in the link budget preparation for environments where similar building materials are used.</em></p> </td> </tr> </tbody> </table> <p>&nbsp;</p> J. Akanni, O. T. Oraiye, A. A. Isa, O. Ogunbiyi Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Assessment of energy potential of municipal solid waste from university of derby student residence <table> <tbody> <tr> <td> <p><em>Solid waste generated from the University of Derby Student Residence was used to examine the amount of thermal energy that can be reclaimed from the waste. The waste material used for the analysis was categorized into different constituents which were used for analyzing the sample, from which the recoverable energy was estimated. The calorific value of the waste mixture was found to be 34.28 MJ/kg with a corresponding thermal energy recoverable estimated to be 1532.96 MJ/day, which gave an equivalent power of 425.82 kWh/day. The findings from this study suggests the necessity for the adoption of waste management systems that will integrate energy recovery from wastes in order to supplement the increasing demand for energy.</em></p> </td> </tr> </tbody> </table> N. S. Gukop, J. A. Japhet, B. D. Lengs, A. Adesanmi Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Strength properties and microstructural characterization of metakaolin geopolymer concrete synthsized at ambient temperature. <table> <tbody> <tr> <td> <p><em>Geopolymer concrete has been gaining extensive attention in recent years due to its numerous advantages over Ordinary Portland cement concrete in terms of reduced carbon footprint, improved mechanical strength, durability as well as chemical resistance. However, production of geopolymer concrete is usually affected by several factors such as the synthesis temperature, nature of the source material and the type of alkaline activator used. For these materials to have wider application within the Nigerian construction industry, there is a need to synthesize the concrete at ambient temperature and to examine the suitability of native Alkaleri kaolin to produce geopolymer concrete. The study presents the strength and microstructural properties of Metakaolin Geopolymer Concrete synthesized at ambient temperature. Alkaleri calcined kaolin from Bauchi state Nigeria was used as the main geopolymer precursor with sodium hydroxide and sodium silicate as the alkaline activating agent.&nbsp; The Geopolymer concrete was prepared with Silicon/Aluminium ratio of 2.0 and 2.5 (Geopolymer concrete M1 and M2 respectively) and cured for 3, 7, 14, 28, and 90 days at ambient condition (average temperature of 26°C and average relative humidity of 61± 15%). Fourier Transform Infra-Red, X-ray Diffraction, Thermo-Gravimetric Analysis, Scanning Electron Microscopy as well as compressive strength and split tensile strength test were conducted on the Geopolymer concrete at appropriate curing age to examine their microstructure and strength properties. The Fourier Transform Infra-Red revealed that there was an immediate geopolymeric reaction between the metakaolin and the alkali activator. The X-ray Diffraction showed that the raw metakaolin sample and both Geopolymer concrete M1 and M2 were amorphous in nature; while the Geopolymer concrete M2 (Silicon/Aluminium ratio of 2.5) exhibited good dissolution of the kaolinite which resulted in a more compact and stable structure in comparison with Geopolymer concrete M1 (Silicon/Aluminium ratio of 2.0). This was also confirmed by the Scanning Electron Microscopic images of the Geopolymer concretes.&nbsp; The Thermo-Gravimetric Analysis revealed that both Geopolymer concrete M1 and M2 were thermally stable at 300°C and at 800°C, only the organic phase of the geopolymer decomposed. The strength properties (compressive and tensile strength) of Geopolymer concrete M1 and M2 increased with increase in the curing age, and Geopolymer concrete M2 displayed slightly higher strength in all the curing ages as compared with the Geopolymer concrete M1. This implies that the higher the Silicon/Aluminium ratio, the higher the mechanical strength of the geopolymer. Both the Geopolymer concrete samples attained a compressive strength that can be acceptable for structural use as normal strength concrete grade C20/25 as specified in the requirement of BS EN 206-1 2000 at 28 days curing.</em></p> </td> </tr> </tbody> </table> C. H. Salihu, A. E. Abalaka, R. A. Lafiya-Araga, B. J. Olawuyi, I. Kariim Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Analysis of the Seasonal Variation in Turbidity Index in Sudan and Fresh Water Swamp Vegetation Zones, Nigeria <table> <tbody> <tr> <td> <p><em>This study evaluates the seasonal turbidity index of two vegetation zones in Nigerian which are Sudan and Fresh water swamp. Thirty years (1981 – 2010) meteorological data of temperature, relative humidity and solar radiation were obtained from the archives of the Nigerian Meteorological agency (NIMET). Annual and monthly analysis of the turbidity coefficients were mainly based on the Linke and Angstrom methods, due to absence of radiosonde data. The results show that the monthly mean values of the clear-sky global radiation lies between 19.34 MJ/m2day to 24.44 MJ/m2day (for Sudan vegetation) and 15.54 MJ/m<sup>2</sup>day to 20.28 MJ/m<sup>2</sup>day (Fresh water swamp). Meanwhile, the monthly percentages of clearness index above 0.6 were estimated as 75% and 33.3, and for the water vapour content exceeding 3 cm to be 58.3% and 100%, for the Sudan and Fresh swamp vegetation, respectively.&nbsp; These values contribute significantly to the reduction of direct radiant energy. The results obtained for the seasonal index for Linke and Angstrom coefficients show that for the wet season, the index exceeded the dry value by 25.99% and 23.66% for Sudan and Fresh swamp vegetation, respectively. By implication, the Fresh water Swamp is laden with more aerosols than Sudan zone. Additionally, the R2 obtained for the relationship between Angstrom and Linke is 0.999 for both locations. Hence, the study provides an insight into the contribution of aerosol in the attenuation of solar radiation over the atmosphere for these locations.</em></p> </td> </tr> </tbody> </table> S. U. Muhammad, W. C. Solomon, D. B. Yahaya, J. S. Enaburekhan Copyright (c) 202`1 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400 Prediction of mass and volume of Tacca involucrata tubers using physical characteristics <table> <tbody> <tr> <td> <p><em>Knowledge of physical properties of crops is necessary for the development of processing machines. Relationships between the various physical properties of crops could also be useful in ensuring proper handling and more efficient design of processing machineries. This study was therefore, aimed at developing mathematical models for predicting the mass and volume of Tacca involucrata tubers using some physical characteristics of the crop. Physical characteristics of Tacca tubers at average moisture content of 73.3% (wet basis) namely axial dimensions, Arithmetic Mean Diameter (AMD), Geometric Mean Diameter (GMD), projected areas along the three mutually-perpendicular axes, criterion area (Ac), mass and volume were determined. Out of 240 samples used in the study, data from 120 samples were used for development of the prediction models while the remaining were used for validation of the developed models. Data analysis tool in Microsoft Excel (2013 version) was used to carry out regression analysis and develop the predictive models. Statistical parameters namely correlation coefficient, coefficient of determination, root mean square error and mean bias error were used to determine the goodness of fit of the predictive models. The mass and volume models were divided into three classifications namely: single and multiple variable regression models based on axial dimensions; single and multiple variable regression models based on the projected areas; single variable regression model based on volume (for mass prediction only). Average length, width, thickness, AMD and GMD of the tubers were 71.88, 57.22, 46.71, 58.60 and 57.57 mm respectively while average criterion area, longitudinal, cross-sectional and transversal projected areas were 2614.24, 2580.61, 2097.04 and 3165.07 mm<sup>2</sup> respectively. Average mass and volume of the tubers were 129.30 g and 111.55 cm<sup>3</sup> respectively.&nbsp; All the developed models performed well in predicting the mass and volume of Tacca tubers (R<sup>2</sup> ≥ 0. 905) except for those based on the axial dimensions as single independent variables (R<sup>2</sup> ≤ 0.890). The predicted mass and volume of Tacca tubers were not significantly different (p ≤ 0.05) from the experimentally observed values for all the classifications considered. Mass and volume modelling based on a single variable of any of the projected areas was the most convenient modelling for Tacca tubers since it involves the use of a single image capturing device and the whole measurement could therefore, be automated. The developed models would be useful for automated sorting and packaging of Tacca tubers.</em></p> </td> </tr> </tbody> </table> A. O. Raji , B. O. Oyefeso Copyright (c) 2021 Arid Zone Journal of Engineering, Technology and Environment published by University of Maiduguri, Nigeria. Wed, 01 Sep 2021 00:00:00 -0400