This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.
Modern trends have appeared recently in educational thought that call for the achievement of the outcomes of the educational process. Some of these trends are the development of individual thinking skills, considering the individual differences, and learning basic skills. The five-year learning cycle is one of these models. It is called as five-year learning cycle because it passes through five stages. These five stages are: (operate - discover - clarify - expand – Evaluate), which make the learner as the main axis for activating thinking processes. This can be done by organizing study materials through research, investigation, and identifying concepts by himself, as in learning sports skills that depend on motor performance and teamwork,
... Show MoreThe increase of the scenographic designer role on account of the character of the director in the Iraqi theater constituted a clear phenomenon that has been manifested in many shows, which necessitated a stance on the nature of this relation and delimiting the work space for each one of them inside the theater show. The research focuses on determining the work relation between the directorial vision and the scenographic proposal in the Iraq theater show. The research is divided into four chapters, the first one addressed the methodological framework, where the research problem was stated in the following question (has the scenographic designer been able through his scenographic proposal to remove the director from his position being the
... Show MoreThe MTS-88. c trainer is a training system targeting students in the microprocessors course. It has a built in single-line assembler allowing the users to enter programs in assembly. It has the problem that long programs cannot be traced and tested efficiently. A simple error may cause all the code to be erased and the system to stop responding. Also, this system lacks the ability to be connected to the PC. The aim of this work is to modify the system to make it possible to be connected to the PC through the parallel port. This gives the capability to download long programs to the system after being developed in the PC. The 8255 Programmable Peripheral Interface available in the teaching system is interfaced to the parallel port and used as
... Show MoreThe research's purpose is to highlight the role that the Approach of the strategic decision play in universities' governorships, assuming that the universities' governorship are definite result that can be reached by modern universities through their active strategic decisions that they take based on the correct way of thinking and the appropriate entrance that achieve the strategic goal of these decisions. The current research depended on two curriculums necessitated by the research requirement which are the analytical description curriculum and compare curriculum, the field research was done in the (Baghdad and Al-Mustansiriya) universities, the samples that were selected were the president, assistants and members of the board'
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This research is included in the study of one of the most important rules of jurisprudence, which is (necessity descends the status of necessity, controls and applications) branching from the major rule (hardship brings facilitation) and since the jurisprudential rule is defined as knowledge of a total or majority rule that applies to all its parts. He has to know all the branches that fall under him, which leads to understanding Sharia, controlling jurisprudential issues and linking them to its rules, so that no contradiction occurs, and he has the jurisprudential faculty that he promotes in consideration and diligence. And what is meant by need: is what is lacking in terms of expansion and raising the distress that often lea
Abstract. Froth flotation is a solid-liquid separation technique that uses hydrophobicity as a driving force. Bacteria and other drinking water microorganisms tend to be hydrophobic and can be removed from water using this application. The biggest limitation against using froth flotation in the drinking water industry is the difficulty of producing froth without chemical frothers and holding bacteria in this froth without chemical collectors which deteriorate water taste and odor. Recently, researchers at the University of Sheffield described a method for producing froth using only water and compressed air. This has enabled froth flotation to be studied as an alternative to biocides for the removal of bacteria from drinking water. T
... Show MoreEnvironmental education is considered as process of getting Humans in communication with this environment and all its various resources. such process requires acquiring knowledge about the environment that com help humans understand their correlative relations with the environmental elements on one hand and among the environmental elements themselves on the other . Besides, such a process requires developing human skills that help them participate in developing environmental circumstances. Therefore environmental education is responsible for perspective and cultural development that governs human behavior. Regarding their environment and stimulating tendencies and interests towards the environment , let alone helping humans acquire the c
... Show MoreThe research aimed at identifying the level of Acute stress disorder and orientation towards supplication among the wives of the martyrs and knowledge of the two levels according to the age groups, academic achievement and profession. Sample of (72) wife of a martyr, and the results of the research indicated that the wives of the martyrs have symptoms of distress disorder and have adherence to the supplication to alleviate that disorder, as well as the results indicated that there are statistical differences in distress disturbance according to the variable of age groups, the profession variable and the variable of enrollment The academic year. As for the measure of the trend towards supplication, there are no statistical dif
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