Algerian journal of engineering and technology
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Item Adsorptive, kinetic and thermodynamic investigations of Sarcocephalus latifolius leaves extract as corrosion inhibitor on alloy steel in 0.6M HCl solution(جامعة الوادي - university of el oued, 2022-11-19) Iorhuna, Fater; Abdullahi, Muhammad AyubaOne of the materials that have many uses in the manufacturing, automotive, and construction industries is the alloy steel. When exposed to harsh environments this material is susceptible to deterioration and corrosion. Because of this reason, it is necessary to safeguard this valuable material. There have been many different methods used, but inhibition using particularly plant extract has reportedly been effective and acceptable to the environment. In this study, the behavior of alloy steel in 0.6M HCl at various concentrations of Sarcocephalus latifolius extract was assessed using weight loss and surface characterization methods of analysis. The plant extract's ability to inhibit corrosion increased during the weight loss experiment from 25.56% to 61.18% as concentration of the plant extract increased with a decrease in temperature from 323K to 303K respectively. Thermodynamic parameters of the inhibitory process were discovered to classify the process as feasible and spontaneous, obeying the Freundlich adsorption isotherm model's description of physical adsorption. The kinetic analysis of the inhibitory process demonstrates that it follows the first order model, with activation energy and half-life values rising with the concentration of the plant extract. In conclusion, Sarcocephalus latifolius extract is effective in inhibiting the corrosion of alloy steel in 0.6M HCl at low temperatures and higher plant extract concentrations through surface adsorption.Item Application of HEC-RAS model for adaptive water allocation in a Large-Scale Rice Irrigation Scheme(جامعة الوادي - university of el oued, 2021-09-30) Ismail, Habibu; Kamal, Md Rowshon; Shanono, Nura Jafar; Amin, Sunusi AbubakarWater allocation is a key component of good water management in an irrigation system. Water imbalance between upstream and downstream has been a major issue at Tanjung-Karang Rice Irrigation Scheme Malaysia. This study applied the HEC-RAS model to estimate water for supply and analysed its allocation to the demand in the scheme. Water demand was computed based on water requirement, effective rainfall and seepage/percolation. Results of R2, NSE, PBIAS and RSR during the model calibration and validation were 0.66, 0.64, 0.94 and 0.60; and 0.65, 0.59, 1.77 and 0.64, respectively. The irrigation scheme was under-supplied from January-March and over-supplied from April-June during the off-season. While in the main-season was under-supplied from July-September and over-supplied from October-December. Similarly, the excess water during the off and main seasons for the period was 40.10 and 52.40 Mm3 respectively. Whiles the deficit water during the same seasons was 52.46 and 53.14 Mm3, respectively. This suggests providing an adequate storage facility, which could store excess water during low water demand and use it in the period of water shortage. The developed model could therefore assist in estimating the over/under-supply with respect to the demand thereby storing the excess for use during the period of high demand.Item Application of polyvinylpyrrolidone-iodine complex as corrosion inhibitor for carbon steel using an experimental design method(جامعة الوادي Université ofEl-Oued, 2022-01-28) Attar, Tarik; Benchadli, Abbes; Mellal, Tayeb; Benabdelkader, Ilyes; Dali Youcef, Boumediene; Choukchou-Brahama, EsmaCorrosion processes are responsible for numerous losses, especially in the industrial sector. Inhibitors are commonly used to prevent corrosion in acidic medium. The aim of this study was to apply an experimental design to optimize the influencing parameters such as inhibitor concentration, temperature and immersion time on the corrosion inhibition of polyvinylpyrrolidone-iodine (PVP-I) complexes on carbon steel using the weight loss technique (WL). The parameters of the corrosion protection process were optimized and predictive mathematical models were developed using the Response Surface Methodology (RSM) using the Central Composite Design (CCD). It was also found that the data predicted by the regression analysis had a good agreement with the data obtained from the experiments, with the values R2 = 0.999 and Adj. R2 = 0.997 for the inhibitory effect. The best efficiencies for experiments that were not performed were determined by experimental design (DOE).Item Application of polyvinylpyrrolidone-iodine complex as corrosion inhibitor for carbon steel using an experimental design method(جامعةا الوادي university of el oued, 2022-01-28) Benchadli, Abbes; Mellal, Tayeb; Benabdelkader, Ilyes; Dali Youcef, Dali Youcef; Brahama, Esma ChoukchouCorrosion processes are responsible for numerous losses, especially in the industrial sector. Inhibitors are commonly used to prevent corrosion in acidic medium. The aim of this study was to apply an experimental design to optimize the influencing parameters such as inhibitor concentration, temperature and immersion time on the corrosion inhibition of polyvinylpyrrolidone-iodine (PVP-I) complexes on carbon steel using the weight loss technique (WL). The parameters of the corrosion protection process were optimized and predictive mathematical models were developed using the Response Surface Methodology (RSM) using the Central Composite Design (CCD). It was also found that the data predicted by the regression analysis had a good agreement with the data obtained from the experiments, with the values R2 = 0.999 and Adj. R2 = 0.997 for the inhibitory effect. The best efficiencies for experiments that were not performed were determined by experimental design (DOE).Item A brief review of features of copper indium disulphide (CuInS2) nanomaterials for quantum dot solar cells(جامعة الوادي Université ofEl-Oued, 2023-10-06) Garg, NityaCopper indium disulphide CuInS2 (CIS) is found to be an interesting nanomaterial belong to group I-III-V for quantum dot solar cell (QDSCs) application due to low toxicity, multiple exciton generation effect, high light absorption in the visible spectral range, appropriate band gap that coordinate well with the solar spectrum, unusual radiation tolerance, noticeable defect tolerance and low cost. Properties of this material that makes it important for use in quantum dot solar cell is also discussed in this paper. This paper summarizes the research going on in the field of synthesis of CuInS2 nanomaterials reported by different authors across the globe. Optical and photovoltaic properties of reviewed CIS QDSCs is also highlighted in this paper.Item Broken rotor bars fault detection in induction motors using FFT: simulation and experimentally study(University of El-Oued, 2019-12-28) Kechida, Ridha; Menacerb, Menacerb; Cherifa, HakimaThis paper presents the fault detection of broken rotor bars based on the analysis technique, such as the fast Fourier transform (FFT), which utilize the steady-state spectral components of the stator quantities is considered. This technique has been given expected results, the accuracy of this technique depends on the loading conditions and constant speed of the motor. This method shows good theoretical and experimental resultsItem Causes of pavement failure of Edunabon – Sekona road, Osun State, Nigeria(جامعة الوادي Université ofEl-Oued, 2022-05-31) Mohammed, HusseinThe study investigated the Edunabon-Sekona road, Osun State, in Southwest Nigeria, to determine the causes of its failure. A condition survey of a five kilometre stretch of the road was carried out to visually assess and characterize 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 were determined, using standard procedures. Deflection at every point as well the representative rebound deflection was determined using appropriate equations. The condition survey showed widespread 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 1.10 mm. The study concluded that the pavement failed due to the low relative density and representative rebound deflection values of the subgrade.Item Combating chloride ions in reinforced concrete using K2Cr2O7 as corrosion inhibitor(جامعة الوادي - university of el oued, 2020-11-28) Mayowa Ikumapayi, Catherine; Adedamola Adeniji, Akintayo; Osamudiamen Idehen, Emmanuel; Barnabas, Abel AdeizaThe ingress of chloride ions from seawater in contact with concrete reinforced structures is one of the major causes of deterioration in the construction industries worldwide. This gives rise to corrosion of embedded steel in the concrete structures which sooner or later results in dilapidation, deterioration and partial or total failure of the reinforced structure. In this study potassium dichromate (K2Cr2O7) solution was used to mitigate the effects of chloride ions in reinforced concrete. Cylindrical concrete samples of size 15mm x 36mm diameter with cement to sand mix ratio of 1:6 and a water cement ratio of 0.5 were prepared. 12 mm high yield reinforcing bars were inserted into the sample. The samples were then immersed in NaCl solution with varying concentration of K2Cr2O7. Both weight loss method and linear polarization measurement were performed on the samples. Data acquisition and analysis were carried out using 4 decimal places electronic weighing balance, a potentiostat interfaced and a computer. The results from the weight loss method showed that the weight loss decreased from 0.7629g to 0.1398g for the 7th and 35th day respectively. Results from the potentiodynamic polarization method further revealed the efficiency of K2Cr2O7 in mitigating corrosion.Item Comparative studies between aluminium sulphate, moringa seed and green plantain peel as coagulants(جامعة الوادي - university of el oued, 2021-09-18) Ogbozige, Francis James; Nwobu, Helen UzoamakaAluminium sulphate (alum) is the most commonly and widely used coagulant in water treatment plants however, literatures have revealed that it has certain setbacks that needs to be addressed including imparting acidity and hardness to water. Hence, the coagulation capacities of the seeds of moringa (Moringa oleifera) and peels of unripe or green plantain (Musa paradisiaca) which are abundantly available and currently considered as waste in most developing countries, were investigated in comparison with alum. This was achieved by using standard methods to treat raw water at different dosages of coagulants (100-600mg/l) prepared from moringa seed and plantain peel, and comparing the performances of these coagulants with that of aluminium sulphate (alum) used in treating same raw water at same dosages. Parameters checked are turbidity, pH and hardness. Results showed that alum performed best in terms of turbidity removal followed by moringa seed solution and then plantain peel solution. This is because alum reduced the water turbidity by 99.94% at an optimum dosage of 100mg/l while moringa seed and plantain peel solutions reduced the turbidity by 80.27% at 300mg/l and 63.99% at 500mg/l respectively. Nevertheless, it was noted that at optimum dosage of alum, the water pH was reduced from 6.7 to 6.2 as against the WHO permissible limits (6.5 – 8.5), and the harness level was increased by 22.43%. On the contrary, at the optimum dosages of moringa seed and plantain peel solutions, the pH were raised to 7.3 and 7.5 respectively, which is within the permissible limits and also, the hardness levels were reduced by 13.41% and 8.52% respectively. It was concluded that moringa seed solution could replace alum successfully but plantain peel solution needs modifications in order to improve the turbidity removal capacity before replacing alum although, it could be used in the absence of other conventional coagulants.Item Comparative studies of the curing and hardening process of soaps produced from locally processed saturated and unsaturated fatty acids(جامعة الوادي - university of el oued, 2021-08-08) Faruk, Mohammed Umar; Akeeb, Nuruddeen Adebayo; Bello, Kalgo Yusha'upaper presents a comparative study of the curing and hardening processes of five soaps produced from Nigerian local oils (Palm oil, Palm-kernel Oil, Groundnut oil, Shea-butter oil and Tallow oil). The curing process was investigated by drying the soap samples under natural conditions and obtaining their daily moisture loss for duration of 21 days. Hardness tests based on the Brinell Hardness Methodology was conducted using a locally improvised manual indenter with a test load of 6.585kgf or 64.553N. Graphical plots of the moisture loss versus a one day time interval showed that all the soaps exhibited similar behaviour in the curing process, characterized by exponential decay in the rate of moisture loss. Superimposition of the curves into one graph showed very close fitting between the curves, indicating that the rates of moisture loss are very close. Graphs of the hardening process of the soaps showed that there are similarities in the hardening behaviour of the soaps with the curves exhibiting two hardening regions, a region of non-linear hardening and a region of constant hardening. Results showed that the hardness of the soaps varies in this order: tallow (1.88 HN) >shea butter (0.3 HN) >palm kernel (0.25 HN >palm Oil (0.15 HN) > groundnut oil (0.13 HN).Item A conceptual framework for assessing the impact of human behaviour on water resource systems performance(جامعة الوادي - university of el oued, 2020-06-21) Shanono, Nura Jafar; Ndiritu, JohnThe persistent poor performance of water resource systems (WRS) has been reportedly linked to not only climate change and dilapidated water infrastructures but also human unlawful activities. Some of these unlawful activities include unauthorized water abstractions, wastage, excessive losses, discharging untreated wastewater, over‐application of chemicals and fraudulent incidences. Despite advances in WRS planning and operational analysis, incorporating such undesirable activities to quantitatively assess their impact on WRS performance remain elusive. This study was then inspired by the need to develop a methodological framework for WRS performance assessment that integrated human impacts with WRS analysis tasks. A conceptual framework for assessing the impact of human behaviour on WRS performance using the concept of socio-hydrology is proposed herein. The framework identifies and coupled four major sources of water values (WRS, goals, managers and users) using three activities serving as the missing links between these values (interactions, outcomes and feedbacks). The framework can be used as a database for choosing relevant social and hydrological variables and to understand the inherent relations between the selected variables to study a specific human-water problem in the context of WRS management.Item Corrosion inhibition effect of benzaldehyde (Methoxybenzene) for Aluminium in sulphuric acid solution(جامعة الوادي - university of el oued, 2020-11-13) Abdullahi, Ayuba; Muhammad, AbubakarCorrosion 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 surfaceItem Corrosion inhibition potentials of Strichnos spinosa L. on Aluminium in 0.9M HCl medium: experimental and theoretical investigations(جامعة الوادي - university of el oued, 2020-11-21) Muhammad Ayuba, Abdullahi; Ameenullah, AbdullateefAluminium is known as one of the most useful metals on earth which is also subject to corrosion under certain environments. Many methods have been used to minimize its corrosion, but the use of inhibitors is widely accepted. The use of green inhibitors has gained wide usage because of its environmental friendliness. The experimental studies of the corrosion inhibition potentials of Strichnos spinosa L was carried out using weight-loss and Fourier transform infrared spectroscopy (FTIR), whereas theoretically, quantum chemical parameters and molecular dynamic stimulations of some compounds isolated from the plant in literature were studied. The analyses of the experimental results showed that the extract of Strichnos spinosa L. extract decreased the corrosion rate of Aluminium in 0.9M HCl in the order: 0.2g/l < 0.4g/l < 0.6g/l respectively from 303-323K. The inhibition efficiency decreased with increase in temperature and was found to be 84.7%. FTIR results showed that the inhibition mechanism is physical through the functional groups present in the extract. The data obtained were fitted into various adsorption isotherms and relatively the Freundlich isotherm was found to be the best fit. Relying on quantum chemical parameters and molecular dynamic stimulations results, the adsorption/binding strength of the concerned inhibitor molecules on Aluminium surface follows the order Ursolic acid>Betulinic acid>Erythrodiol. The computed adsorption/binding energy values (Eads) for the various isolated compounds from the plant indicate the adsorption process to be non-covalent (physiosorption) which is in good agreement with the experimentally determined adsorption mechanism.Item Design, construction and performance evaluation of a cucumber slicing machine(جامعة الوادي - university of el oued, 2022-10-02) Nuhu Jibril, Abdulaziz; Aliyu Mashi, Abubakar; Muazu Shu’aibu, SuleimanThe cucumber slicing machine was designed, constructed and it is performance was evaluated. The major components of the slicing machine are the power unit, slicing compartment, knife compartment, collecting vessel were all fabricated and mounted on the machine. The performance parameters of the machine such as slicing efficiency, percentage loss, and output capacity were evaluated. T-test was used to compare the mean values of these parameters for manual and mechanical slicing. The average efficiency of the manual and mechanical slicing was found to be 71.84 % and 90.0 % respectively. The average percentage loss of the manual and mechanical slicing was found to be 5.5 % and 14.08 % respectively. The average output capacity of the manual and mechanical slicing was found to be 30 kg/hr and 165.60 kg/hr respectively. The efficiency of manual slicing is significantly higher than mechanical slicing. However, the mean value for mechanical percentage losses and output capacity is significant than manual slicing.Item Effect of rice straw ash on soil properties and yield of cucumber(University of El-Oued, 2019-12-28) Muazu Dantala, Zakari; Babangida, Ibrahim; Nasid, Nuraddeen Mukhtar; Jafar Shanonoa, Nura; Muntaqqa, Ibrahim; Tijjani, Usman; Abubakar, AhmadMany farmers in Nigeria are paying close attention to using Rice Straw Ash (RSA) as a soil fertility enhancement additive. The short and long-term effects of applying this ash to the soil quality were not adequately investigated, however. This research was conducted at the Departmental Farm of Agricultural and Environmental Engineering, Bayero University, Kano to access the impact of RSA on the soil’s physiochemical properties and on cucumber yield. Twelve (12) experimental plots were treated with different amounts of RSA (0 Kg, 1 Kg, 2 Kg and 3 Kg) to assess the intensity effect of the treatment on both soil physiochemicals and crop yield. For each experimental plot, soil properties (moisture content, porosity, bulk density, electrical conductivity, organic matter, pH and sodium concentration, nitrogen, phosphorus, potassium, calcium and magnesium) were measured and analyzed before and after the experiment. The results showed that the application of ash increased moisture content, bulk density, porosity, electrical conductivity, organic matter and sodium concentration while reducing the pH, nitrogen, phosphorus, potassium, calcium and magnesium levels. The mean yield in 0 Kg RSA (21,84tons / ha) was found to be the highest. There was a drop in the yield (13.08-14.14tons / ha) of crop in the plots treated with RSA. The research concluded that continued use of RSA could lead to a reduction in crop yield as the EC level was found to be rising. It is on this basis that farmers are advised to avoid the use of RSA as an additive for soil fertility enhancement and other means should therefore be used.Item Effect of selected admixtures on the geotechnical properties of black cotton soil(جامعة الوادي Université ofEl-Oued, 2022-06-23) Osinubi, Kolawole Juwonlo; Eberemu, Adrian Oshioname; Yohanna, Paul Polycarp; AzigeThe effect locust bean waste ash (LBWA) and cement kiln dust (CKD) on black cotton soil (BCS) was studied. BCS was modified with 0, 2, 4, 6, 8 and 10 % LBWA and 0, 1, 2, 3 and 4 %CKD in relation to the soil dry weight. Test carried out include cation exchange capacity (CEC), Atterberg limits, compaction and shear strength test. Results show that a combination of LBWA and CKD have negative effect on the geotechnical properties of soil with exception in few cases. The CEC increased with increase in both the LBWA and CKD contents with deviations in few cases. Values of 21.9, 24, 34.1, 33.5, 32.1 and 33.8 Cmol/Kg were recorded at 0, 2, 4, 6, 8 and 10% LBWA content. Similar trend was observed for 1, 2, 3 and 4% CKD. Liquid limit generally increased with increase in LBWA content while plastic limit generally decreased. In the case of plasticity index, values increased with increase in LBWA content. Peak values were recorded at 6%LBWA content. Maximum dry density (MDD) decreased with increase in LBWA content. MDD values of 1.68, 1.67, 1.66, 1.65, 1.63 and 1.61 were recorded at 0, 2, 4, 6, 8 and 10% LBWA content. Similar trend was observed for 1, 2, 3 and 4% CKD. Optimum moisture content (OMC) increased with increase in LBWA content. Cohesion of soil decreased with increase in LBWA content. Values of 140, 110, 95, 60, 120 and 180 kN/m2 was recorded at 0, 2, 4, 6, 8 and 10% LBWA content, while angle of internal friction improved from its natural value up to 10% LBWA content. Statistical studies by means of two–way analysis of variance (ANOVA) reveal that LBWA and CKD have significant effect on the soil properties. Although the modified soil did not effectively improve the consistency and shear strength parameters of BCS, an optimal blend of 2% CKD/10% LBWA blend slightly improved the soil properties. The optimally modified soil could be utilised for lightly trafficked roads construction as sub-base materials.Item Effect of selected oven drying temperatures on the quality of Tiger Nut (Cyperus Esculentus) and Ginger Nut (Zingiber Officinale)(جامعة الوادي Université ofEl-Oued, 2023-03-23) Nuhu Jibril, Abdulaziz; Aliyu Ishaq, AbubakarThe present study was to evaluate the effect of selected drying temperatures on the quality of tiger nut (Cyperus Esculentus) and ginger (Zingiber Officinale). The temperatures used were 25, 50, and 75°C for 4 hours. The quality composition determined were moisture content, crude protein, crude fiber, crude fat, ash content, and carbohydrate. From the results, the tiger nut parameters that show significant difference at the three drying temperatures 25, 50, and 75°C with their mean values were moisture content 0.05, 0.20, and 1.05%, crude protein 8.75, 6.56, and 5.47%, and crude fat 10.28, 14.60 and 12.65%. For ginger nuts were moisture content was 1.25, 2.15, and 2.60%, and crude protein was 15.31, 14.22, and 17.50%. While the parameters that show no significant difference at the three drying temperatures 25, 50, and 75°C with their mean values were crude fiber 1.26, 1.27, and 1.28%, ash content 2.95, 3.95, and 4.90%, and carbohydrate 76.75, 74.62, and 75.72. For gingers were ash content 8.7, 6.50, and 7.35%, crude fat 8.72, 10.43 and 9.20%, crude fiber 1.42, 1.23 and 1.28%, and carbohydrate 65.84, 67.63, and 64.67. Drying temperatures are crucial in affecting food internal structure, composition and widely practiced as a method of preserving agricultural products because of its ease and affordabilityItem Effect of selected oven drying temperatures on the quality of Tiger Nut (Cyperus Esculentus) and Ginger Nut (Zingiber Officinale)(جامعةا الوادي university of el oued, 2022-01-28) Nuhu Jibril, Abdulaziz; Abubakar, Aliyu IshaqThe present study was to evaluate the effect of selected drying temperatures on the quality of tiger nut (Cyperus Esculentus) and ginger (Zingiber Officinale). The temperatures used were 25, 50, and 75°C for 4 hours. The quality composition determined were moisture content, crude protein, crude fiber, crude fat, ash content, and carbohydrate. From the results, the tiger nut parameters that show significant difference at the three drying temperatures 25, 50, and 75°C with their mean values were moisture content 0.05, 0.20, and 1.05%, crude protein 8.75, 6.56, and 5.47%, and crude fat 10.28, 14.60 and 12.65%. For ginger nuts were moisture content was 1.25, 2.15, and 2.60%, and crude protein was 15.31, 14.22, and 17.50%. While the parameters that show no significant difference at the three drying temperatures 25, 50, and 75°C with their mean values were crude fiber 1.26, 1.27, and 1.28%, ash content 2.95, 3.95, and 4.90%, and carbohydrate 76.75, 74.62, and 75.72. For gingers were ash content 8.7, 6.50, and 7.35%, crude fat 8.72, 10.43 and 9.20%, crude fiber 1.42, 1.23 and 1.28%, and carbohydrate 65.84, 67.63, and 64.67. Drying temperatures are crucial in affecting food internal structure, composition and widely practiced as a method of preserving agricultural products because of its ease and affordability.Item Electrodeposition of CaCO3 on stainless steel 316 L substrate: influence of thermal-hydraulics and electrochemical parameters(جامعة الوادي - university of el oued, 2021-04-14) Amzert, Sid Ahmed; Arbaoui, Fahd; Boucherit, Mohamed Nadir; Selmi, Noureddine; Salah, HaniniIn this paper we study the effect of the hardness, the rotation speed, the temperature and the cathodic polarization on calcium carbonate scale deposit on rotating stainless steel electrode using electrochemical techniques. The scale deposit was investigated by X-Ray diffraction, scanning electron microscope, Infrared spectroscopy and electrochemical impedance spectroscopy (EIS). The electrochemical results show that the Oxygen Reduction Reaction (ORR), which is responsible of CaCO3 electrodeposition, takes place with 4 electrons at low rotation speed lower than 600 rpm and 2 electrons at high rotation speed upper to 1000 rpm. The recovery times of concentrations: 100, 300 and 600 mg/L are respectively 2.0 h 20 min, 1 h 20 min and 1 h. The morphology of the CaCO3 scale deposit shows that the crystals formed in the center of the electrode have small sizes compared to those of the periphery. Whatever the hydrodynamic or thermodynamic conditions, the Calcite form remains predominant. Other forms appear in particular conditions: at high temperature up to 50°C the aragonite form and at high cathodic polarization about -1.2 V/SCE the vaterite form.Item Empirical Assessment of Mixed Traffic Congestion on Selected Arterials in an Urban Metropolis, Nigeria(جامعة الوادي - university of el oued, 2022-09-27) Ako, Terseer; Tunde, Yusuf Ibrahim; Mije, Fwanshak GaiusThe 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