Algerian Journal of Engineering and Technology (AJET)
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Causes of pavement failure of Edunabon – Sekona road, Osun State, Nigeria
Get PDFThe study investigated Edunabon-Sekona road, Osun State, in Southwest Nigeria, with a view to determining the causes of its failure. Condition survey of a five kilometre stretch of the road was carried out to visually assess and characterise the pavement distresses. In situ density tests were conducted using the core cutter method at intervals of 500 m along the route. Soil samples were collected at these intervals for laboratory tests and selected engineering properties determined, using standard procedures. Deflection at every point as well the representative rebound deflection was determined using standard equations. The condition survey showed wide spread distresses. The average in-situ density (IDD) value was 1.55 g/cm3, while the maximum dry density (MDD), relative density (RD) and deflection (δ) mean values were, 1.94 g/cm3, 80 % and 0.66 mm, respectively. The representative rebound deflection (δrrd) was 0.66 mm. The study concluded that the pavement failed due to the low relative density and representative rebound deflection values of the subgrade
Optimization of a gas-fired gurasa (local bread) baking oven using response surface methodology (RSM)
Get PDFGurasa (local bread) is an important diet in many households in Northern parts of Nigeria for time immemorial, especially in Kano State, Nigeria. This study is to develop a gurasa baking oven, carry out the performance evaluation of the oven and also to optimize the baking parameters of the oven using the response surface methodology (RSM). The oven is composed of three baking compartments; these include a heat source, a control panel and the main frame. The baking compartments consist of heating rods and the gurasa baking trays. The heat source is a gas burner that generates the required heat to bake the products. There is a control panel that is used to set the temperature at which the gas cylinder goes off (after the preheating of the oven) and the heat in the oven is maintained for some time with the aid of the insulator in between the walls. Using the response surface method, the oven was evaluated to know its baking efficiency, baking damage, and capacity. The oven has a baking efficiency of 87.5 %, baking damage of 11.5 % and a capacity of 23.4 kg/hr with 27 loaves per batch. The RSM showed values of the responses ranged from 16 – 95 g, 5.24 – 13.6 %, 845.8 – 3684.2 N/m2 and 0.7–8.06 cm3/g for weight loss, moisture content, tensile strength and specific volume respectively. Quadratic models to predict weight loss, moisture content, tensile strength and specific volume of gurasa in terms of baking temperature, baking period and mass of dough were developed. The optimum baking process was achieved at a baking temperature of 200oC, a baking period of 9 minutes and a dough mass of 130 g. These values show that the oven can be adopted for domestic and commercial baking
Legionella: Health Impacts, Exposure Evaluation, and Hazard Reduction
Get PDFLegionella pneumophila is an intracellular pathogen, omnipresent in the nature and seen as opportunistic. It is the main source of legionellosis that can take place in its nonpneumonic form (Pontiac fever) and acute pneumonic form (Legionnaires’ disease). In the aquatic systems, L. pneumophila can conquer and remain alive intracellularly in different protozoans. The faculty to multiply inside biofilms gives more safeguard from natural stresses like disinfection. Human contagion by L. pneumophila happens following the inhalation or aspiration of aerosols carrying the pathogen. This work defines microbiologically Legionella bacteria and presents a brief history relating to their first discovery and following contagions, a short description relating to their metabolism and physiology, a discussion of their clinical characteristics and their subsistence in the nature and growth in a biofilm, and a general examination of numerous technologies employed for their removal. The spread of opportunistic pathogens (OPs) remains the most significant feature of microbial potable water quality besides the generation of disinfection by-products (DBPs). The (re)growth of OPs and the production of DBPs in urban engineered water systems both closely correlate with the injections or concentrations of disinfectant residuals. Nonetheless, OPs and DBPs respond to disinfectant residuals frequently oppositely. An elevated residual concentration efficiently suppresses the (re)growth of OPs while intensifies the production of DBPs. Oppositely, a low or “detectable” disinfectant residual level decreases the generation of DBPs but could not stop OPs from thriving. To guarantee that the overall or combined health risks of OPs and DBPs are minimum, OP (re)growth and DBP generation must be deeply revised while selecting a practical disinfectant residual dosage or level
Transient electron transport in the ternary alloys AlxGa1-xN, InxGa1-xN, AlxIn1-xN using the Monte Carlo method of simulation.
Get PDFThe transient electron transport and overspeed phenomenon in the binary cubic compounds GaN, InN and AlN and their ternary alloys AlGaN, InGaN and InAlN are examined and compared. For all these alloys, the overspeed phenomenon occurs beyond the critical field at which electrons can pass from the valence band to the conduction band. This field is relatively large for these alloys, particularly when the molar fraction of aluminum is large in the InAlN and AlGaN alloys. This field can reach 500 kV/cm for AlN and it is smaller in alloys with high indium concentration. It is 70 kV/cm for InN. Thus, the critical field for these alloys can vary from kV/cm to 500 kV/cm, including 150 KV/cm for GaN. The overspeed phenomenon becomes greater in the presence of Indium and it is less important in the presence of Aluminum. The present work focuses on the electronic transport in the alloys AlxGa1-xN, InxGa1-xN and InxAl1-xN in the transitional mode by using the Monte Carlo method of simulation which is the most appropriate
An investigation on the climate change and drought types in the Porsuk Stream Watershed, west of Turkey
Get PDFClimate change is a major parameter affecting agriculture. The aim of the study is to determine the effect of climate change on agricultural and hydro-meteorological drought in the Porsuk Stream Watershed. In this study, drought analyses in the watershed had been conducted using the past (1970-2018) and future (2020-2100) climate data produced according to the RCP 4.5 and 8.5 scenarios of the HadGEM2-ES model, with the help of Standard Precipitation Index (SPI), Standard Runoff Index (SRI) and Palmer Drought Severity Index (PDSI). The analysis revealed that the watershed was located in a dry region, it was detected that agro-hydrological droughts were dominant, and a meteorologically normal climatic situation prevailed in the past. Sub-basin in the watershed where agricultural drought is experienced severely are Odunpazari, Alpu and Tepebasi, respectively. 1981, 1986, 1989, 2008, 2013, 2015 and 2018 years were arid, while the driest years are expected to be 2056, 2058, 2069, 2070, 2089, 2096, the wettest year is expected to be 2021. The Porsuk Stream Watershed inclines to be dry meteorologically and humid hydrologically in the future. From the point of agricultural drought, although there is a potential for a drought over time, it is detected that a normal climatic situation will prevail throughout the watershed. Compared to the reference (1970-2000) period, climate change will happen in the manner of temperature and precipitation increases in the future. As a result of the study, important data about drought were produced for farmers
Morphological properties of heat treated date fruits (Phoenix dactylifera L.) in postharvest
Get PDFIn this research, fresh harvested date palm (Phoenix dactylifera L.) was treated with heat treatment at 55 ±2°C for 20 min in a ventilated oven. The effect of this heat treatment on date fruits quality was investigated during 5 months of storage at room temperature storage 22 ±1°C of temperature with 75 to 80% of relative humidity (RH), and 10 ±1°C with 85 to 90% of relative humidity (RH). Morphological characteristics of the samples were studied. Results indicated that during storage the morphological characteristics changed significantly. The width of date samples stored at 10°C is significant compared to heat-treated and not heat-treated samples stored at room temperature. The major change was observed for the sample of heat-treated dates stored at 10 ±1°C has the highest weight compared to the other samples of the dates studied. The R-Index quality showed a rate of 8.56% and which increased in heat-treated dates to reach 8.87%. Harvesting at Tamr stage followed by treating the fruits with heat treatment, showed to be a promising method for maintaining date palm fruit storage quality
Sand Dunes Reviewing: Wind Effect and Dunes Classification
Get PDFDrylands are distributed in many parts of the world. The combined effects of land mismanagement, unsustainable use of water, and climate change have caused the transformation of many areas into drylands, and as a result, increase desert areas and the formation of aeolian sand dunes. Due to the increase in construction activities in drylands areas, more descriptions of the formation of soils in aired zones, the effect of wind erosion on these soils, and their classification and movement are required so as to assess their effect on such activities. This paper described the wind action on aeolian dunes, it's reviewed the occurrence, movement, and classification of dunes. The effect of direction and intensity of the wind on the length, height, and location of dunes was presented. The saltation, suspension, and creep movements of sand grains were discussed. The challenges of the classification of the sand dunes were, also, included as a part of this review. It was found that there is a significant effect of the dune morphology on sediment movement and "wind flow lines". The determination of dune morphology is related to many interdependent factors, the assessment of these factors is difficult. Due to their varying sizes and shapes, sand dunes classification was found to be a challenging
A Laboratory study on water transfer properties of unsaturated compacted lateritic Soil – Bacillus coagulans mixtures
Get PDFA study on soil water characteristic curves (SWCC) and unsaturated hydraulic conductivity (UHC) of lateritic soil–Bacillus coagulans mixes was done. Three well known models (i.e van Genuchten (VG), Brooks-Corey(BC) and Fredlund-Xing (FX)) were used to predict SWCC and UHC from laboratory test results. Soil samples for the test were admixed with B. coagulans at one-third (1/3) pore in step suspension densities of 0 to 2.4x109cells/ml. Soil samples were then compacted differently with Reduced British Standard light (RBSL), British Standard light(BSL),West African Standard (WAS) and British Standard heavy(BSH) compactive efforts. Cementitious reagent was injected into the compacted soil using gravity up until saturation was attained. Specimens after being compacted were then cored out from the mould using stainless steel cylindrical moulds. The specimens (i.e., inside the stainless steel cylindrical moulds) were then immersed in water chamber till the samples were completely saturated via capillary action and thereafter allowed to undergo a pressure plate drying(PPD) test. Matric suctions of 0, 10, 30, 100, 500, 1000 and 1500kPa, respectively, were used. Result of SWCCs show that with a rise in matric suction, the volumetric water content(θ) declined progressively for all the models (i.e van Genuchten (VG), Brooks-Corey(BC) and Fredlund-Xing(FX)) and the experimental measured values. The UHC slightly reduced with rise in B.coagulans suspension density for VG, BC and FX models. At 500 and 1500kPa matric suctions (MS), BC model documented the least UHC values and satisfied the regulatory lowest hydraulic conductivity value of 1.0×10-9m/s for use in containment system. Thus, is suggested for modelling the UHC of lateritic soil ̶ B.coagulans mixtures
Empirical Assessment of Mixed Traffic Congestion on Selected Arterials in an Urban Metropolis, Nigeria
Get PDFThe study was aimed at investigating the appropriateness and development of congestion indices and predictive model with operational parameters for congestion on the roads of a developing city. A manual 12-hour (6.00 am- 6.00 pm) traffic count was conducted for seven consecutive days of the week and converted to passenger car units (pcu) on Gboko, Iorchia Ayu, Otukpo, Joe Akaahan, Atom Kpera and Lafia roads of Markurdi to determine congestion spots. Five parameters of volume, headway, speed, density and delay were derived from the generated database in accordance with Highway Capacity Manual of 2010. Traffic congestion indices, with corresponding predictive models, were quantified, and a 15-year congestion forecast made to obtain the future operating scenarios on Makurdi roads. Makurdi roads were dominated by cars of 38.09-61.87%, motorcycles of 15.58-22.85%, minibuses of 10.63-31.33%, and tricycles, luxurious buses, lorries/trucks, trailers/tankers of 0.03-7.75%; with operating significant parameters at peak period of 2322-3134 pcu/h., 305-990 pcu/km., 1.7-2.2 s and 17-40 km/h for the volume, density, headway and speed, respectively; the degree of congestion on the selected routes were moderate to severe (volume capacity ratio of 0.51-1.32) and substantially dependent on the operating parameters, predictive model for the roadway traffic congestion index, CI = 107.071+0.028v+10.054Sl +0.013c with R2 = 0.97, was generated with volume (v), segment length (Sl) and capacity (c); and a 15-year projection indicated that Joe Akaahan Road would be heavily congested. All other segments would be severely congested. The present and 15-year projected CI values were 1.83 and 3.77 respectively, indicating extra vehicle kilometer travel due to congestion of 377%. It is recommended that congestion indices and predictive model are useful tools for management of congestion on urban roads of a developing city
Corrosion inhibition effect of benzaldehyde (Methoxybenzene) for Aluminium in sulphuric acid solution
No full textCorrosion inhibitory effect of benzaldehyde (methoxybenzene) on aluminium in sulphuric acid media was studied by weight loss measurement and characterization was carried by FTIR analysis. From the results it was found that increase in inhibitor concentration lead to the increase in inhibition efficiency and decreases when the temperature increased. Plots of ln (wi - Δw) against time gave a linear graphs which confirmed a first order reaction mechanism for aluminium in inhibited and uninhibited acid solution. The activation energy value of uninhibited acid solution was found to be 36.39 kJ/mol which increased to 62.32 kJ/mol when 0.1 M concentration of the inhibitor was added. There was a decreased in the values of the rate constant from uninhibited to inhibited acid solution while those of half-life increased from uninhibited to inhibited acid. The obtained values of entropy change (ΔS), enthalpy change (ΔH) and Gibbs free energy of adsorption (ΔGads) were also evaluated and discussed. The activation energy values and that of Gibbs free energy of adsorption support the physisorption mechanism between the molecules of the inhibitor and Aluminium surface.