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Nhb9T4cBVTCNdQwCL0Tz
The dynamics of nutrient, toxic phytoplankton, nontoxic phytoplankton and zooplankton model
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<p>The objective of this paper is to study the dynamical behavior of an aquatic food web system. A mathematical model that includes nutrients, phytoplankton and zooplankton is proposed and analyzed. It is assumed that, the phytoplankton divided into two compartments namely toxic phytoplankton which produces a toxic substance as a defensive strategy against predation by zooplankton, and a nontoxic phytoplankton. All the feeding processes in this food web are formulating according to the Lotka-Volterra functional response. This model is represented mathematically by the set of nonlinear differential equations. The existence, uniqueness and boundedness of the solution of this model are investigated. The local and global stability conditions of all possible equilibrium points are established. The occurrence of local bifurcation and Hopf bifurcation are investigated. Finally, numerical simulation is used to study the global dynamics of this model.</p>

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Publication Date
Wed Jan 01 2025
Journal Name
Agricultural Engineering
The Effect of Design and the Accelerated Wear Test of Agricultural Nozzles on the Resulting Droplet Size
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Abstract<p>The change in the size of the droplets during the pesticide application process could have a negative impact on the percentage of drift or the losses of pesticides to the environment. One of the factors that could affect the droplet size produced from a single nozzle is the internal design of the nozzle itself, in addition to the wear of the nozzle orifice as a result of the usage time. In this research, three types of nozzles with different internal designs were used (Turbo TeeJet (TT), Turbo TwinJet (TTj 6011003), and Drift Guard (DG 11003)). The nozzles were subjected to an accelerated wear test for one hundred hours, and different droplet size parameters (Dv 0.1, Dv 0.5, Dv 0.9), </p> ... Show More
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Publication Date
Sun Dec 01 2013
Journal Name
Baghdad Science Journal
The Ecology and geographical distribution for the species of the genus Salvia L. of labiatae in Iraq
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The study included general survey of some districts of Iraq in order to determinate new distribution areas for 33 species of the genus salvia L. ,new collections obtained , new locations for many species recorded. Observed specimens in most Iraqi herbaria were studies and identified. ,the flowering period were also studied

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Publication Date
Sun Dec 31 2000
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Preparation of Zeolite 4A and Studying the Operating Conditions of the Agglomeration in the Inclined Rotary Disk
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Publication Date
Sun Dec 01 2013
Journal Name
Baghdad Science Journal
The Ecology and geographical distribution for the species of the genus Salvia L. of labiatae in Iraq
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The study included general survey of some districts of Iraq in order to determinate new distribution areas for 33 species of the genus salvia L. ,new collections obtained , new locations for many species recorded. Observed specimens in most Iraqi herbaria were studies and identified. ,the flowering period were also studied

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Publication Date
Tue Jan 17 2023
Journal Name
Mesopotamian Journal Of Cyber Security
The Purpose of Cybersecurity Governance in the Digital Transformation of Public Services and Protecting the Digital Environment
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The process of digital transformation is considered one of the most influential matters in circulation at the present time, as it seeks to integrate computer-based technologies into the public services provided by companies or institutions. To achieve digital transformation, basics and points must be established, while relying on a set of employee skills and involving customers in developing this process. Today, all governments are seeking electronic transformation by converting all public services into digital, where changes in cybersecurity must be taken into account, which constitutes a large part of the priorities of nations and companies. The vulnerability to cyberspace, the development of technologies and devices, and the use

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Publication Date
Fri Mar 01 2019
Journal Name
Al-khwarizmi Engineering Journal
The Effect of Adding Carboxymethyl Cellulose and Zinc Sulfate on the Corrosion Characteristics of the Drilling Fluid
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Drilling solutions can be considered as an intricate mixture comprising of number of chemical additives which aid specific needs such as controlling the rheological properties and reducing corrosion. Inhibitors are substances that are added in small concentrations to corrosive environment to decrease the corrosion. Their applications can be found in drilling equipments. The effect of adding Zinc Sulphate and Carboxymethyl Cellulose to study their influence on the corrosion of carbon steel in Bentonite mud has been evaluated using Weight Loss Technique. This study focuses on determining rheological properties and corrosion characteristics. Results show CMC and ZnSO4 work as inhibitors when added to the Bentonite with inhibition

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Publication Date
Sat Sep 30 2023
Journal Name
Journal Of The College Of Education For Women
The Prophetic Speeches (Hadith) on Sciences and Scientists: Application of the "Text from Text and D+" Theory
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This study aims to apply the theory of "Text from Text and the Plus Dimension" in the analysis of the Prophetic discourse found in the section on the virtues of knowledge and scholars from Imam Sahih al-Bukhari's book. This section covers several topics, including the virtue of gathering for the sake of learning, the superiority of a scholar over a worshipper, the excellence of jurisprudence in the religion of Allah, the acquisition of knowledge through the passing away of scholars, the merit of inviting people to Allah, the continuing benefit of beneficial knowledge after a scholar's demise, the warning against seeking knowledge for purposes other than Allah, and the Prophet seeking refuge from knowledge tha

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Publication Date
Sat Dec 01 2012
Journal Name
Journal Of Engineering
Numerical and experimental investigation on the performance of the capillary tube using R-134a and R-600a
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In this paper, isobutane (R-600a) is used as a suitable substitute for (R-134a) when changing the length of capillary tube. And the experimental data on capillary tube are obtained under different conditions such as (subcooling and ambient temperatures) on domestic refrigerator (9ft3 size), this data shows that (R-600a) a suitable substitute for (R134a) .The test presented a model for a steady state, two-phase flow in capillary tube for vapour compression system .The numerical model depends on conservation equations (mass, energy and momentum) as wall as the equation of state for refrigerant. The solution methodology was implemented by using finite difference techniques. The system results indicate that it is possible to change the refri

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Publication Date
Sat Mar 30 2024
Journal Name
مجلة نسق
Education Skills and Their Role in the Health and Psychological Development of the Child An Anthropological Study
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The study highlighted the transformation of value systems and educational patterns between past and present, especially with the introduction of modern variables and means, such as mobile phones, the internet, social media, and others. These factors have contributed both positively and negatively to the study. The study highlights the integral role of the school in collaboration with the family in guiding and educating children. It also emphasizes the active role of the school in developing students' abilities and skills, either attracting them to school or vice versa. This includes an examination of the essential skills required in education and their role in achieving a state of psychological well-being and systematically developing child

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Publication Date
Wed Jan 08 2025
Journal Name
Egyptian Journal Of Veterinary Sciences
Histological and Histochemical Study of the Esophagus Before and After Crop in the Guinea Fowl (Numida meleagris)
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