The first studies on shocks and vibrations were carried out at the beginning of the 1930s to improve the behavior of buildings during earthquakes. Vibration tests on aircraft were developed from 1940 to verify the resistance of parts and equipments prior to their first use. Flutter is a well-known example of dynamic aero elasticity, where when oscillation of structure interacted with unsteady aerodynamic forces the flutter will occur. Vibration on any structure without damping means that self-harmonic oscillation will occur, and in most cases the oscillation may start to increase until structural failure. This behavior is very similar to resonance phenomena if only the oscillation is being studied as a vibration case. In vibration suppression, the active vibration control is one of the more effective technique which is used for attenuating bad effects of disturbances on structure. In this work, two different composite wings have been used; one of them is made of Glass-fiber random matt and the other is made of woven ({0/90} Glass-fiber). The proportional-integral-derivative (PID) control is employed here for studying the suppression of active vibration wing affected by wind velocity flow through wind tunnel in the laboratory of mechanical engineering department at the university of Baghdad. Piezoelectric (PZT (transducers are used as sensors and actuators in vibration control systems. The attack angle was 10 degrees and three different velocities (15, 20, 35 m/s) have been taken to show their effect on the wings vibrations suppression. Is noticed that the suppression of the wing amplitude is reduced when the wind velocity increases for both woven and random composite wing matt. This is happened due to the vortex which has became more violent increase in wind velocity. It is concluded that the composite woven wing has high resistance more than the composite random wing. Also, the maximum control amplitude of woven matt is 1.9 cm and the damping is about 33% at 25 m/s wind velocity while the amplitude is 2.22 cm and the damping is about 53% at 10 m/s wind velocity for random wing.
The present study aims at finding out the (effect of the Caroll’s pattern on the second intermediate class pupils' achievement in geography)
The partial experimental design of two groups, experimental and control, with pre-post tests is used. The sample is represented in (74) female pupils. The sample is divided into two groups (38) experimental group and (36) control one. The sample is selected from first intermediate class pupils ( Am Salama Secondary School for girls) \ Baghdad\ Al-karkh-1, for academic year 2015-2016.
The researcher has equalized the two groups in several variables: the previous achievement tests, intelligence, age in months, the scor
... Show MoreThe effect of some environmental factors in the loss rate for high weights virgins are full to the screwworm fly of the ancient world and included temperatures 15,20,25,30,35,40 study showed that the rate of loss in weight virgins advanced to full participants at a temperature of 15 C while notgets evolution
The current research is concerned with methods of formation and their effect on the sintering process of ceramic materials. The research is divided into a number of chapters. The first chapter addressed the research structure (the research problem, importance, objective, limits, and it also defined the terms used in the research). The second chapter addressed the theoretical framework, where the theoretical framework has been divided into three sections. The first section dealt with methods of formation of ceramic materials including: Plasticizing method 2- semi-dry pressing method 3- dry pressing method 4- extrusion method 5- casting method.
The researcher found that there is a clear difference between the methods through her formati
The research deals with the impact of the nature of social and political formation in the orientation towards extremism through tracking the institutions and beliefs that the individual is going through. The role of the family, the group, the school, education, and religion has been touched upon in acquiring the trends of extremism, whether publicly or covertly, Focusing on the social and economic contexts that are an incubator environment for extremism supported by the form of the group and the beliefs it espouses, whether direct through religion or indirectly through the nature of education, this study relied on political literature that addressed this The topic, which focused on the phenomenon of extremism that swept the world recentl
... Show MoreThere have been many advances in the solar chimney power plant since 1930 and the first pilot work was built in Spain (Manzanares) that produced 50 KW. The solar chimney power plant is considered of a clean power generation that needs to be investigated to enhance the performance by studying the effect of changing the area of passage of air to enhance the velocity towards the chimney to maximize design velocity. In this experimental and numerical study, the reduction area of solar collector was investigated. The reduction area that mean changing the height of glass cover from the absorbing plate (h1=3.8cm, h2=2.6cm and h3=1.28cm). The numerical study was performed using ANSYS Fluent software package (version 14.0) to solve go
... Show MoreThis research aims to introduce the importance of electronic marketing and the extent of its impact on the quality of the insurance service in general, and the national insurance company in particular, and the advantages it can achieve, an increase in its competitiveness, as well as contributing to increasing the efficiency of the performance of the insurance company.
The research relied on the questionnaire form as a main tool for obtaining data and information by the 70 questionnaire questionnaires required for the field side of the research, as they were distributed and retrieved in full, and all of them are suitable for analysis. The sample .The questionnaire was designed with three axes, the first wa
... Show MoreThis research highlights the light on the general framework of accounting discloser in the Islamic banks, and show the types and the concepts of Cost Efficiency, In this present study, the sample included Fourteen Islamic banks, where the data was collected from the annual financial reports. Accordingly, the study in order to achieve the aims and access to the results based on the analytical method and the descriptive analysis, and conducted a Simple & Multiple Linear Regression analysis, in order to test hypotheses of the research by using of statistical analysis software (SPSS). The research has arrived to many results such as: the commitment of Islamic banks working in the Kingdome of Bahrain (Wholesale) to the requirements of the
... Show MorePoly aniline-formaldehyde/chitosan composite (PAFC) was prepared by the in situ polymerization method. It was characterized by FTIR spectroscopy in addition to SEM, EDS and TGA techniques. The adsorption kinetics of malachite green dye (MG) on (PAFC) were studied for various initial concentrations (20, 30 and 40) mg/L at three temperatures (308, 313 and 318) K. The influence factors of adsorption; adsorbent dose, contact time, initial concentration and temperature were investigated. The kinetic studies confirmed that adsorption of MG obeyed the pseudo-second-order model and the adsorption can be controlled through external mass transfer followed by intraparticle diffusion mass transfer. A study of th
This study uses the performance of the discretionary estimation models by using a sample of listed companies in the Netherlands and Germany. The actual accounting framework provides a wide opportunity for managers to influence data in financial reporting. The corporate reporting strategy, the way managers use their discretionary accounting, has a significant effect on the company's financial reporting. The authors contribute to the literature through enhancement to these models to accomplish better effects of identifying earnings management as well as to present evidence that is particular to the Dutch and German setting.
For this, we followed the methodology of Dechow, Sloan, and Sweeney (1995) and Chan
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In the last years, the self-balancing platform has become one of the most common candidates to use in many applications such as flight, biomedical fields, industry. This paper introduced the simulated model of a proposed self-balancing platform that described the self–balancing attitude in (X-axis, Y-axis, or both axis) under the influence of road disturbance. To simulate the self-balanced platform's performance during the tilt, an integration between Solidworks, Simscape, and Simulink toolboxes in MATLAB was used. The platform's dynamic model was drawn in SolidWorks and exported as a STEP file used in the Simscape Multibody environment. The system is controlled using the proportional-integral-deriva
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