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Variable Structure Control Design for a Magnetic Levitation System
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In this paper the variable structure control theory is utilized to derive a discontinuous controller to the magnetic levitation system. The magnetic levitation system model is considered uncertain, which subjected to the uncertainty in system parameters, also it is open-loop unstable and strongly nonlinear. The proposed variable structure control to magnetic levitation system is proved, and the area of attraction is determined. Additionally, the chattering, which induced due to the discontinuity in control law, is attenuated by using a non-smooth approximate. With this approximation the resulted controller is a continuous variable structure controller with a determined steady state error according to the selected control parameters. Finally the ability and the effectiveness of the proposed continuous variable structure controller to the magnetic levitation system are verified via numerical simulations. When state initiated inside the area of attraction, the results show that the ball position can be directed to follow various desired positions, with steady state error not exceeding .  

 

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Publication Date
Fri Jun 21 2013
Journal Name
Journal Of Engineering
Combined effect of fineness modulus and grading zones of fine aggregate on fresh properties and compressive strength of self compacted concrete
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Self-compacted concrete (SCC) considered as a revolution progress in concrete technology due to its ability for flowing through forms, fusion with reinforcement, compact itself by its weight without using vibrators and economic advantages. This research aims to assess the fresh properties of SCC and study their effect on its compressive strength using different grading zones and different fineness modulus (F.M) of fine aggregate. The fineness modulus used in this study was (2.73, 2.82,2.9& 3.12) for different zones of grading (zone I, zone II& marginal zone(between zone I&II)) according to Iraqi standards (I.Q.S No.45/1984).Twelve mixes were prepared, each mix were tested in fresh state with slump, V-Funnel and L-Box tests, then 72

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Publication Date
Sat Jul 01 2023
Journal Name
The Egyptian Journal Of Hospital Medicine
Evaluation of the Antibiofilm Activity of Laurus nobilis Leaves Extract and Assessment of Its Effect on fimA and papC genes in Escherichia coli isolates
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Background: The beneficial gut bacterium E. coli can cause blood poisoning, diarrhoea, and other gastrointestinal and systemic disorders. Objective: This study amid to examines the antibiofilm activity of Laurus nobilis leaves extract on E. coli isolates and compares pre- and post-treatment gene expression of fimA and papC genes. Subjects and Methods: Ten isolates of E. coli were obtained from the Genetic Engineering and Biotechnology Institute, University of Baghdad, which was previously collected from Baghdad city hospitals and diagnosed by chemical tests, the diagnosis was confirmed using VITEK-2 System. The preparation of the aqueous and methanolic Laurus nobilis leaves extracts was done by using the maceration method and Soxhlet appara

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Publication Date
Wed Jan 02 2019
Journal Name
Journal Of The College Of Languages (jcl)
Conflict of characters in the works of Jacob Steinberg story: סכסוך הדמויות ביצירותיו הסיפוריות של יעקב שטיינברג
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A character is one of the most important pillars of narrative production. Most critics believe that a character is the focus of events.

   Jacob Steinberg, a Jewish writer who is Ukrainian by origin, wrote many stories, most of which spoke about the lives of Jews in the diaspora, especially in Ukraine. The environment there has been reflected in his stories.

    Steinberg focused on the role of characters in shaping these productions.

   In this study, we discuss the conflict of characters in Steinberg's stories. This conflict is characterized by different trends and goals. There is a conflict with the environment, a conflict with society, a conflict with the self,

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Publication Date
Thu Mar 01 2018
Journal Name
Journal Of Engineering
Permeability Estimation by Using the Modified and Conventional FZI Methods
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There many methods for estimation of permeability. In this Paper, permeability has been estimated by two methods. The conventional and modified methods are used to calculate flow zone indicator (FZI). The hydraulic flow unit (HU) was identified by FZI technique. This technique is effective in predicting the permeability in un-cored intervals/wells. HU is related with FZI and rock quality index (RQI). All available cores from 7 wells (Su -4, Su -5, Su -7, Su -8, Su -9, Su -12, and Su -14) were used to be database for HU classification. The plot of probability cumulative of FZI is used. The plot of core-derived probability FZI for both modified and conventional method which indicates 4 Hu (A, B, C and D) for Nahr Umr forma

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Publication Date
Thu May 18 2023
Journal Name
Journal Of Engineering
Spatial Prediction of Monthly Precipitation in Sulaimani Governorate using Artificial Neural Network Models
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ANN modeling is used here to predict missing monthly precipitation data in one station of the eight weather stations network in Sulaimani Governorate. Eight models were developed, one for each station as for prediction. The accuracy of prediction obtain is excellent with correlation coefficients between the predicted and the measured values of monthly precipitation ranged from (90% to 97.2%). The eight ANN models are found after many trials for each station and those with the highest correlation coefficient were selected. All the ANN models are found to have a hyperbolic tangent and identity activation functions for the hidden and output layers respectively, with learning rate of (0.4) and momentum term of (0.9), but with different data

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Publication Date
Sat Feb 01 2014
Journal Name
Journal Of Economics And Administrative Sciences
The impact of customer contact on operation performance Case study in the specialist Dental Centre in Al-alwia
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the researchers Sought to determine the impact of the customer contact (Within a client contact there are two times, first is the total time required to create a service and within it there is contact time while the second time is the time of client contact ؛ where means a time that records the physical presence of the customer during the process of service) on operations performance by concentrate attention on the cost (labor productivity) and quality (patient ratio to the doctor) and speed (cycle time) and flexibility (the flexibility range) , as well as ruling out variable of innovation because of impossibility to measure this variable in the Specialty Center for Dental in al-alwia due to the center is lacking of mechanisms t

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Publication Date
Wed Jun 01 2011
Journal Name
Journal Of Economics And Administrative Sciences
The effect of the repurchase policy in stock tradingIn financial markets - case study
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The research dealt with the case stock repurchase policy of Emaar Real Estate Company one of listed companies in Dubai Stock exchange. The research has launched from the cognitive dimensions of repurchasing policy which took great concern in the literatures of financial management, and also this policy became as substitute for distributing the monitory profit in the last three decades in the international financial markets, but it did not get any importance in the Arab Markets such as that of the Arab Gulf in addition to the Iraqi Stock Exchange.

The research summarized a set of conclusions, the most important one was the consistence of analysis result with the test of the major two hypotheses (The first

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Publication Date
Sun Sep 01 2019
Journal Name
Journal Of Physics: Conference Series
Mineralogy of Sand Fraction in Selective Soil Sections in Baghdad City
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Abstract<p>This study has been undertaken to investigate the mineralogical properties and morphological features of sand fraction in some soils of Baghdad / Iraq.The morphological features of sand fractions were studied by Polarized optical microscope. Results have shown that the grains of these minerals from samples of sands have different colors, those from the surface horizons have dark brownish spots, due to staining by organic matter, and have a yellowish– to yellowish brown spots due to accumulation of Iron oxides.Results of light minerals indicated that quartz is dominant due to effect of parent material of these soils. Two types of opaque minerals (black and brown) are found, whereas t</p> ... Show More
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Publication Date
Sat Dec 30 2023
Journal Name
Journal Of Economics And Administrative Sciences
The Impact of Strategic Cohesion on Administrative Excellence
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This research aims to test the effect of strategic cohesion with its dimensions (organizational excitement, organizational casting, organizational synergy) as an independent variable on administrative excellence as a dependent variable in the Ministry of Planning, and through surveying several employees (general managers, heads of departments,  and units managers). As a research community, and based on the importance of the research topic in the aforementioned research community. The researchers have adopted the descriptive-analytical using the questionnaire as the main data collection. 155 questionnaires were distributed, yet,114 of them were retrieved and 110 were used for final statistical analysis. The researchers used the relev

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Publication Date
Wed May 17 2023
Journal Name
College Of Islamic Sciences
The meaning of the triple verb more with one letter in Diwan al-Shafi'i
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The Diwan of Imam Al-Shafi’i acquires great importance, as Al-Shafi’i is an authority in the language, and when I saw that no one had preceded me in exploring its depths, I took my tool and turned my face towards it intending to study the triple verb in it. I stop at these verbs and the student pauses for their morphological forms, looking at the significance of the triple verb more with one letter, two letters, and three letters, and I found that they are many, and such research cannot contain them all, so the choice came to choose the triple verb more with one letter, and the significance of the increase in it, as the increase in The building necessitates an increase in the meaning, and from here the study was limited to the triple

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