The appearance of Mixed Mode Oscillations (MMOs) and chaotic spiking in a Light Emitting Diode (LED) with optoelectronic feedback theoretically and experimentally have been reported. The transition between periodic and chaotic mixed-mode states has been investigated by varying feedback strength. In incoherent semiconductor chaotically spiking attractors with optoelectronic feedback have been observed to be the result of canard phenomena in three-dimensional phase space (incomplete homoclinic scenarios).
Sand production in unconsolidated reservoirs has become a cause of concern for production engineers. Issues with sand production include increased wellbore instability and surface subsidence, plugging of production liners, and potential damage to surface facilities. A field case in southeast Iraq was conducted to predict the critical drawdown pressures (CDDP) at which the well can produce without sanding. A stress and sanding onset models were developed for Zubair reservoir. The results show that sanding risk occurs when rock strength is less than 7,250 psi, and the ratio of shear modulus to the bulk compressibility is less than 0.8 1012 psi2. As the rock strength is increased, the sand free drawdown and depletion becomes larger. The CDDP
... Show MoreThe art of theater penetrated various scientific and human fields, as well as touching the facts and events surrounding it, and scientific innovations had a wide field, so it adopted feedback in interactive theater performances, especially the theater of the oppressed. Then came the indicators that resulted from the theoretical framework for the formation of the tool by which the research sample is analyzed, and then the chapter concluded with previous studies. As for the third chapter, it involved the research procedures, and through the research tool and the research method, and by selecting the intentional sample, the sample represented by a play (the story of Shahrour) was analyzed. As for the fourth chapter, it included the results
... Show MoreThe main purpose of the research is to study the significance of the event in the explicit source and its significance in the Mimi source and to explain the difference between them in the Holy Quran, especially since most linguists were not interested in what the Mime source indicates in the text, but focused on its form and form, as they defined it as the name Linguists and grammarians did not mention a difference in meaning between the explicit source and the Mimi source, and they interpret the second in the first sense, which led me to choose this topic, to know the significance of each source through Appeal to the maqam and occasion in a challenge D The exact meaning.
The Ge0.4Te0.6 alloy has been prepared. Thin films of Ge0.4Te0.6 has been prepared via a thermal evaporation method with 4000A thickness, and rate of deposition (4.2) A/sec at pressure 2x10-6 Torr. The A.C electrical conductivity of a-Ge0.4Te0.6 thin films has been studied as a function of frequency for annealing temperature within the range (423-623) K, the deduced exponent s values, was found to decrease with increasing of annealing temperature through the frequency of the range (102-106) Hz. It was found that, the correlated barrier hopping (CBH) is the dominant conduction mechanism. Values of dielectric constant ε1 and dielectric loss ε2 were found to decrease with frequency and increase with temperature. The activation energies have
... Show MoreWater is the basis of the existence of all kinds of life, so obtaining it with good quality represents a challenge to human existence and development especially in the desert and remote cities because these areas contain small populations and water purification requires great materials and huge amounts of fossil fuels resulting pollution of the environment. Cheap and environmentally friendly desalination methods have been done by using solar distillations. Passive solar stills have low yields, so in this research, the problem is overcome by connecting four heat pipes which are installed on the parabolic concentrator reflector with passive solar still to increase the temperature of hot water to more than 90°C, as a resul
... Show MoreIn this paper, the general framework for calculating the stability of equilibria, Hopf bifurcation of a delayed prey-predator system with an SI type of disease in the prey population, is investigated. The impact of the incubation period delay on disease transmission utilizing a nonlinear incidence rate was taken into account. For the purpose of explaining the predation process, a modified Holling type II functional response was used. First, the existence, uniform boundedness, and positivity of the solutions of the considered model system, along with the behavior of equilibria and the existence of Hopf bifurcation, are studied. The critical values of the delay parameter for which stability switches and the nature of the Hopf bifurcat
... Show MorePMMA films of different thickness (0.006, 0.0105, 0.0206, 0.0385 and 0.056cm) were synthesized by casting process. The temperature and frequency dependence of dielectric constant and AC electrical conductivity measurements at various frequencies (10kHz-10MHz) and temperatures (293-373K) were carried out. Few anomalies in dielectric studies were observed near 313 and 373 K respectively. These points were related to glass transitions temperature. The variation of activation energy and conduction behavior was studied .From the AC conduction studies, it is confirmed that the mechanism responsible for the conduction process is hopping of carriers. The variations of the dielectric constant and loss as function of frequency at different tempera
... Show MoreThe aim of this study was to propose and evaluate an eco-epidemiological model with Allee effect and nonlinear harvesting in predators. It was assumed that there is an SI-type of disease in prey, and only portion of the prey would be attacked by the predator due to the fleeing of the remainder of the prey to a safe area. It was also assumed that the predator consumed the prey according to modified Holling type-II functional response. All possible equilibrium points were determined, and the local and global stabilities were investigated. The possibility of occurrence of local bifurcation was also studied. Numerical simulation was used to further evaluate the global dynamics and the effects of varying parameters on the asymptotic behavior of
... Show MoreThe current study has sought to identify the levels of the compound thinking among secondary school students basing and relying on the opinions of Lipman who sees that the compound thinking consists of creative thinking and critical thinking, In accordance with this point of view, researchers have resorted to build scale of the critical thinking in its final form of (28) item additionally to the adoption of Torrance for the creative thinking which was translated by sayed. Khairallah in 1981 after confirming psychometric Properties Of both scales and then collect scores of both scales and be the final score represented the level of the compound thinking that has been shown by the results of secondary school students they have no skill of
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