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Articles by O.M. Ibrahim
Total Records ( 4 ) for O.M. Ibrahim
  Elzubier A. Salih , Thomas S.Y. Choong , S.Y. Sergie , N.L. Chin and O.M. Ibrahim
  Problem statement: Earlier work on ohmic heating technique focused on viscous food and foods containing solid particles. In this study, the use of ohmic heating on sterilization of guava juice is carried out. Computational fluid dynamics is used to model and simulate the system. Approach: Investigate the buoyancy effect on the CFD simulation of continuous ohmic heating systems of fluid foods. A two-dimensional model describing the flow, temperature and electric field distribution of non-Newtonian power law guava juice fluid in a cylindrical continuous ohmic heating cell was developed. The electrical conductivity, thermo physical and rheological properties of the fluid was temperature dependent. The numerical simulation was carried out using FLUENT 6.1 software package. A user defined functions available in FLUENT 6.1 was employed for the electric field equation. The heating cell used consisted of a cylindrical tube of diameter 0.05 m, height 0.50 m and having three collinear electrodes of 0.02 m width separated by a distance of 0.22 m. The sample was subjected to zero voltage at the top and bottom of electrodes while electrical potential of 90 volts (AC 50-60 Hz) was set at the middle electrode. The inlet velocity is 0.003 m sec-1 and the temperature is in the range of 30-90°C. Results: The simulation was carried with and without buoyancy driven force effect. The ohmic heating was successfully simulated using CFD and the results shows that the buoyancy has a strong effect in temperature profiles and flow pattern of the collinear electrodes configuration ohmic heating. A more uniform velocity and temperature profiles were obtained with the buoyancy effect included. Conclusion: For accurate results, the inclusion of buoyancy effect into the CFD simulation is important.
  M.M. Tawfik , Elham A. Badr , O.M. Ibrahim , Ebtihal M. Abd Elhamid and Mervat Sh. Sadak
  Background and Objective: Salinity is a serious agro-environmental problem which limiting plant growth and productivity especially in arid and semi-arid regions of the world. Most of the developing countries suffer from shortage of cultivated area and lack of water resources as well as increasing salinity of agricultural land as a result of climate changes. So growing non-traditional crops such as halophytic plants is a promising solution to solve problems of saline habitats. Methodology: For this concern, two field experiments were carried out during 2014 and 2015 seasons at the Model Farm of National Research Centre, El Tour, South Sinai to study the impact of organic fertilization with farmyard manure (5 t fed–1), chicken manure (5 t fed–1) and foliar application with KNO3 (2%), Zn-EDTA (100 ppm) as well as their interaction on biomass production, biochemical composition of Spartina patens. Results: Organic treatment (chicken manure 5 t fed–1) significantly increase the fresh weight of different cuttings, total productivity, chlorophyll a+b, crude protein, potassium content and K/Na ratio compared with control treatment or with farmyard manure. On the other hand, organic treatment (Farmyard manure or chicken manure) decreased the contents of soluble carbohydrates, sodium, calcium and proline as well as succulence, osmotic potential values and Ca/Na ratio. Foliar spraying with KNO3 significantly increase fresh weight of different cuttings, total productivity, chlorophyll a+b, crude protein, potassium content and K/Na ratio compared with tap water or Zn-EDTA. Meanwhile foliar spray with tap water significantly increase the contents of soluble carbohydrates percentage, sodium, calcium and proline as well as the values of succulence, osmotic potential and Ca/Na ratio. As for the interaction effect between organic treatment and foliar treatment, data show that, the highest values of fresh weight cuttings, total productivity, chlorophyll a+b, crude protein percentage, potassium content and K/Na ratio were recorded in plants fertilized with chicken manure (5 t fed–1) and sprayed with 2% KNO3. Furthermore, plants sprayed with tap water without organic manure produced the highest content soluble carbohydrates percentage, sodium, calcium and proline as well as succulence and osmotic potential. Conclusion: It can be recommended the applications of both organic fertilizer (5 t fed–1) and foliar spray with K+ and Zn-EDTA under saline sandy soil conditions.
  O.M. Ibrahim , A.A. Gaafar , Asal M. Wali , M.M. Tawfik and Marwa M. El-Nahas
  Background and Objective: Crop simulation models are used for simulating crop growth as affected by management and climate. Simulating the growth of a certain variety in a certain soil, climate and management needs specific parameters of that variety due to the genetic variations among varieties, which are called genetic coefficients. Methodology: Decision Support System for Agrotechnology Transfer (DSSAT) cropping system model has two programs for estimating specific parameters of a variety. Genotype coefficient calculator (GenCalc) and Generalized Likelihood Uncertainty Estimation (GLUE). An experiment was conducted during winter seasons of 2012/2013 and 2013/2014 to simulate the effect of three rates of nitrogen fertilizer (75, 100 and 125 kg N/feddan) on grain yield and its components of wheat cultivar Sakha 93 and to make a comparison between GenCalc and GLUE in their ability to assess the genetic coefficient of the cultivar. Results: Results showed that GenCalc program performed better than GLUE. The results of model validation revealed that the average of the difference between the simulated and observed parameters when using GenCalc were 4.02, 3.96 and 4.14% for biological yield, grain yield and straw yield, respectively, while they were 5.47, 8.32 and 6.12% for the same aforementioned parameters when using GLUE. The GLUE has three disadvantages, first it does not provide estimation for PHINT (Interval between subsequent leaf tip appearances), 2nd it does not provide options for keeping some coefficients fixed, while others are being calibrated like GenCalc, for example in wheat crop there are spring wheats and winter wheats, in GenCalc it can set P1V (required days for vernalization) at 0 meaning that this variety is spring, while in the same time GenCalc are calibrating the other coefficients, 3rd GLUE takes a lot of time for calibration. Conclusion: However, GLUE is more easily to use than GenCalc.
  O.M. Ibrahim , M.M. Tawfik Elham , A. Badr and Asal M. Wali
  To evaluate the performance of 16 wheat varieties based on agronomic parameters using self-organizing map and cluster analysis, a field experiment was conducted during 2013/2014 and 2014/2015 winter seasons at the farm of the National Research Center at Nubaria district, Albehira Governor ate, Egypt. In cluster analysis, all the studied characters were used to construct a distance matrix using the Euclidian coefficient and used to generate dendrogram showing dissimilarity among all the wheat varieties, distance matrix based on Euclidian coefficient for the 16 wheat varieties revealed that dissimilarity ranged from 0.62 between Gemmiza 10 and Beniswef 5-7.73 between Beniswef 6 and Sakha 93, which reveal the diversity among wheat varieties. Cluster analysis classified the 16 varieties into nine clusters whereas, self-organizing map classified the 16 varieties into 11 clusters which accounting for 95% of the variation. The clusters in SOM consist of nodes where, varieties in the same node are more similar than varieties in different nodes in the same cluster. However, varieties in the same cluster are more similar than varieties in different clusters. The results revealed that varieties with higher grain and straw yield were higher in plant height (cm), number of spikes per meter square, spike length (cm) and number of grain per spike suggesting that grain and straw yield were strongly correlated with those parameters than other parameters. Also, the results suggested that using self organizing map is helpful to classify varieties clearly and more interpretable than cluster analysis.
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