Algerian Journal of Engineering and Technology (AJET)
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Local sensitivity analysis of the AquaCrop model outputs for wheat under Semi-Arid water stress condition
Get PDFThe FAO AquaCrop model has been extensively reported to simulate wheat growth and productivity in response to environmental conditions in many parts of the world. However, the calibration of the model could be tedious due to its large number of input parameters. The complexity in the model evaluation could be simplified by conducting a prior sensitivity analysis (SA), which information on it is hard to come-by in the North-eastern Nigeria. The SA of the model’s output variables to its input parameters was conducted using the local sensitivity analysis (LSA) technique. An early maturing REYNA-28 wheat variety was used under water deficit conditions in the semi-arid North-eastern Nigeria. The analysis revealed that the simulation of grain yield was highly influenced by days-to-flowering (DtF), normalized water productivity (WP*), reference harvest index (HIo), crop coefficient when the canopy is complete but prior to senescence (KcTrx) and maximum effective rooting depth (Zx) with sensitivity coefficients (SCs) of 1.23, 1.05, 0.83, 0.75 and 0.61, respectively. Biomass yield was highly sensitive to days-to-emergence (DtE), WP*, KcTrx, number of plants per hectare (den), soil surface covered by individual seedlings at 90 % emergence (ccs) and initial canopy cover (cco). The sensitivity of canopy cover was more to its related parameters such as DtE, maximum canopy cover (CCx), days-to-maximum canopy cover (DtCCx), canopy growth coefficient (CGC), ccs, cco, den and days-to-start of senescence (DtSS). Stress parameters were found to be either insensitive or with negligible sensitivity except lower soil water depletion threshold for canopy expansion (Pexlw). The analysis also revealed that the model outputs were insensitive to half of the model’s input parameters. These parameters could be fixed within their ranges in order to simplify the model and ease its calibration. The influential/sensitive parameters on the other hand require higher consideration during data collection, fine-tuning and calibration. This work can be validated using different SA techniques and wheat variety and under different environmental condition
Sliding mode sensorless control of an asynchronous motor based on an MRAS-type observer
Get PDFThis work deals with the problem of speed control of a sensorless asynchronous motor. Conventional control laws by PI or PID for example, although still widely used, may prove to be insufficient or unsuitable. We then develop control laws by state feedback, their use nevertheless requires the measurement of the state vector. However, in many cases, sensors for measuring all the physical quantities are not available, essentially for cost reasons. An observer, which is a mathematical object, makes it possible to reconstruct this state vector from the only physical measurements available. In this context, we will propose the use of the sliding mode technique, which is a recursive control method and represents a tool for the study of dynamic stability. We will then approach the observers and in particular those resulting from the theory of the reference model (MRAS). In this proposed work, we are interested in the study of the asynchronous motor by the application of the sliding mode which is a relatively recent technique for nonlinear systems. It is combined with the vector control principle with oriented rotor flux to design robust machine control laws. The motor state quantities are estimated by the MRAS algorithm. A comparison of the performances is established to come out with general conclusions and in particular with regard to the use of the observer to estimate the quantities of state of the engine to control it later by this technique
Dynamic simulation of preformed aqueous foam stability for enhanced oil recovery application
Get PDFAqueous foam is a two-phase system consisting of a continuous liquid phase and a dispersed gas phase. Foams are widely used in a variety of industrial operations, such as the enhanced recovery of hydrocarbons. Because of their unique properties, they can solve a variety of reservoir heterogeneity problems, including early gas breakthrough, channeling, and even viscous fingering. A variety of phenomena affect the stability of foams during flow, for example, the drainage process, gas diffusion, and bubble coalescence. In this research, we used the level-set method to simulate foam stability in various aspects, such as factors affecting foam drainage and coalescence phenomena. According to the simulation results, the foam's lifetime is greatly impacted by the phenomena of drainage and coalescence. Moreover, its stability is strongly influenced by salt as well as the type of gas used to generate it
Drought Analysis of Wheat in Humid (Wales) and Dry (Iraq) Conditions
Get PDFIt is necessity to examine the relationships between droughts and plant yields, which are affected by climate change. In this study, by choosing sample countries from the Middle East and Northern Europe, It was aimed to determine the relationship between wheat yields and drought. Considering that Wales represents the wet conditions and Iraq represents the dry conditions in the World, in this study, the drought conditions of these two countries were analyzed with standard precipitation index (SPI), standard runoff index (SRI) and palmer drought severity index (PDSI). In Cardiff, it was determined that the meteorological humidity increased and there is a normal climate in terms of hydrologic. This led to an increase in wheat yields. In terms of meteorologic drought, Iraq cities from arid to humid are Kirkuk, Mosul, Baghdad and Basra, respectively. Agriculturally, they are listed as Basra, Baghdad and Mosul, respectively. It was determined that wheat yield decreases in Iraq were caused by non-climatic factors. Generally, it was determined that drought periods spread homogenously throughout Iraq. Nevertheless, It is determined that drought is much more widespread and severe in Iraq in 2003, 2004 and 1964. In future dry years, production should be supported with irrigation and fertilization in Wales and Iraq
Development of quantification program for neutron activation analysis
Get PDFThis work describes the use of C++ Builder to develop an INAA (Instrumental Neutron Activation Analysis) application for the quantification of trace elements mass fractions in samples from different origins using the relative method. Previously, our NAA laboratory relied on classic method, which caused delays in obtaining results, computational mistakes, and reduced productivity. The new application offers an improved interface with standardized actions, decreasing human error accumulation and provides users with rapid results. To evaluate the application, an INAA experiment using a high-resolution gamma-ray spectrophotometer was used to assess the air quality at Draria site in Algiers, by using an active bio-monitoring air pollution method. Therefore; tree barks, mosses, and lichens were used in this study. Samples and standards irradiations were carried out in NUR research reactor with thermal neutrons flux 1013 n cm-2s-1, and analyzed by gamma spectrometry using HPGe detector. We used the new developed application as well as the old method to calculate concentrations and determined several heavy metals and trace elements (Ba, Br, Co, Cr, Fe, Hf, La, Rb, Sr, Zn, and Ce). Comparison of the obtained preliminary results between the two methods has showed good agreement
Comparative study on the performance of natural and synthesized adsorbents onto uranium (VI) sorption
Get PDFThe aim of this study is to compare the performance of natural and synthesized material to adsorb uranium. Synthesized Silico-Alumino-Phosphate (SAPO) material is compared to raw and chemically activated Algerian Aleppo pine sawdust (Raw-AAPS and CA-AAPS). The uranium sorption parameters, isotherms modelling, kinetic modelling and decontamination factor results, showed that adsorbents used are effective for the removal of uranium (VI) ions and the performance of the adsorbents follows the order: SAPO > CA-AAPS> Raw-AAPS. The natural material presents less sorption capacity comparatively to the synthesized adsorbent, but it is economically favored because of its abundance in nature and its low cost
Al 6061-T6 microstructure and mechanical properties modification under ion beam irradiation at room temperature: Application for Nuclear Research Reactor
Get PDFAl6061 microstructural and mechanical properties modification under ion beam irradiation was investigated using X-ray diffraction (XRD), micro- and nano-indentation techniques. The samples were irradiated with different ions species at different energies and doses. The irradiations were performed at 5UDH-2 Pelletron Tandem accelerator Islamabad, Pakistan and GANIL accelerator, Caen, France. XRD patterns show a drastic effect of ion beam irradiation on the peaks intensity. All peaks disappear after irradiation except the peak (200) and new phase/precipitates emerged at high doses. It is found that the grain size, micro-strain and peaks shift increase/or decrease depending on the ion species and dose. The micro-hardness increases a little bit after irradiation indicating Al6061 hardening by ion beam irradiation. The result of this study demonstrated that the structure and microstructure of Al6061 are significantly changed by heavy ion irradiation. This will affect certainly the Al6061 mechanical properties and, therefore, reduces its lifetime under reactor neutron operation conditions
Effects of absorber layer thickness and doping density on the performance of perovskite solar cells: a simulation analysis using SCAPS-1D software
Get PDFThe photovoltaic devices based on perovskite have witnessed a rapid increase in performance and are moving towards commercialization due to their low-cost electricity production. In this simulation work, we studied the photovoltaic performance of solar cells based on methylammonium tin iodide (MASnI3) perovskite materials using the numerical simulation tool SCAPS-1D. The main objective is to improve the performance of this solar cell by determining the optimum properties for its operation. The influence of different key parameters, such as the thickness of the absorber layer and the doping acceptor density in the same layer, is thoroughly analyzed through SCAPS-1D. The optimized absorber layer with a thickness of 700 nm shows the highest power conversion efficiency of 26.21%. An increase in the doping density in the perovskite layer roughly increases the efficiency performance of the device to 30.21%. Based on our simulation results, it can be concluded that the TiO2/MASnI3/Spiro-OMeTAD structure for PSC is a potential alternative to the third generation of solar cells. It has the potential to be efficient and inexpensive in future research
Effects of holder pasteurization operating parameters on pasteurized raw milk quality
Get PDFA batch pasteurizer could be considered a closed system and it mostly makes use of heat, stirring, or agitation and speed variation as a process parameter for pasteurization. This study investigates if these parameters support the holder pasteurization method using White Fulani cow breed milk samples. The milk samples were pasteurized at 63°C for 30 minutes with slight but insignificant variations in pH values up to 7.55. The stirring speeds used in this study were 30 rpm, 36 rpm, and 42 rpm. The results showed a significant difference in the microbial loads and phytochemical values due to the study treatments. The microbial loads varied between 1.05* 104CFU/ml to 8.25*107 CFU/ml while the phytochemical values were between 0.12 mg/ml to 27.67 mg/ml. The milk samples were poor in phenol and flavonoid but their differences were significant at p≤0.05 after pasteurization. The speed of 30 rpm and 36 rpm did not show a significant difference at p≤0.05 in the fungi counts after the pasteurization. The blade shapes considered were anchor, helical, and vane. These blade shapes used contributed to the holder pasteurization process
Strength of glass powder based high performance concrete during the time
Get PDFRecycling waste glass and protection of the environment with decreasing of the cement use in building are the main context of this research work. The influence of waste Glass Powder very rich in silica SiO2 as partial replacement of Algerian cement without additions based High Performance Concretes with superplasticizers is evaluated, varying the percentage of Glass Powder by 0%, 10% and 20% (by weight of cement). Compression and the three-point bending tests carried out on High Performance Concretes by fixing the water binder ratio and after water cement ratio at 0.35, the results show that the addition of Glass Powder improves the behaviour of the concrete material compared to the handling and the ease of implementation in an appreciable way. The study shows also that compressive and flexural strengths are significantly influenced by the substitution rate of Glass Powder, a drop is noticed at a young age for concrete with Glass Powder (7 and 28days) and strength gains at 90 and 365 days compared to the control concrete with 0%, this admitted that poozolanic and alkali silica reactions occurred from 28 days