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.
Abstract:
Interest in the topic of prediction has increased in recent years and appeared modern methods such as Artificial Neural Networks models, if these methods are able to learn and adapt self with any model, and does not require assumptions on the nature of the time series. On the other hand, the methods currently used to predict the classic method such as Box-Jenkins may be difficult to diagnose chain and modeling because they assume strict conditions.
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The Yemen Kings and gaverners allered notable services to the pilgrims, who
were in their way to perform the pilgrimage to Mecca. Among them Al-Hysen Ibn
Salama (dead 384, Aih). The governer of Al- Zeadiea state, who concern about
pilgrimage route from its beginning at Hudrumot to its end at Mecca Al Makruma, the
distant was estimated by 60th days to pass the way he also eastablished asystem of
water “artesian wells” as long as the pilgrimage way also setting up large Mosqeses
and Marking out the way of the caravans of pilgrimage to save these caravans from
lossing the right way, he setting up under ground water chanal started from Arafat to
holy Mecca in order to ensure water supplies for the erea. This proje
One of the challenging issues encountered during drilling operations is the lost circulation. Numerous issues might arise because of losses, such as wasting of time and higher drilling cost. Several types of lost circulation materials have been developed and are being used to limit mud losses and avoid associated issues. Each solution has benefits and drawbacks.
In this study, a core flooding test was performed to study the effectiveness of polyacrylamide (PAM) granular gel on the reduction of the circulation lost. One common type of fracture characteristic is fractures with tips, commonly known as partially open fracture (POF). However, PAM gel therapy in POFs received little attention in prior research. Models of partly open fra
... Show MoreThis research dealt with shedding light on the nature of material misrepresentations, in addition to knowing the extent to which the quality of accounting information systems contributes to reducing material misrepresentations On the theoretical side, a number of sources were relied upon in dealing with the research problem and presentation of the topic, while in the practical side, it was relied on the questionnaire form, where the research sample was (accountants and auditors), where 50 forms were distributed and 50 were received, and the data was analyzed and hypotheses tested through the program Statistical spss to show the relationship between the variables. The research reached a number of conclusions, the most important of which is t
... Show MoreThere are many aims of this book: The first aim is to develop a model equation that describes the spread of contamination through soils which can be used to determine the rate of environmental contamination by estimate the concentration of heavy metals (HMs) in soil. The developed model equation can be considered as a good representation for a problem of environmental contamination. The second aim of this work is to design two feed forward neural networks (FFNN) as an alternative accurate technique to determine the rate of environmental contamination which can be used to solve the model equation. The first network is to simulate the soil parameters which can be used as input data in the second suggested network, while the second network sim
... Show MoreThis research deals with the use of a number of statistical methods, such as the kernel method, watershed, histogram and cubic spline, to improve the contrast of digital images. The results obtained according to the RSME and NCC standards have proven that the spline method is the most accurate in the results compared to other statistical methods
Background: Blood vessels injury is one of the most
common causes of medical emergencies that admitted to
hospitals and at the same time it regarded as one of the
most important causes of death. They may represent less
than 15% of all injuries; they deserve special attention
because of their severe complications.
Objective: The aim of the present study is to assess
anatomically the injures of major arteries and veins in the
lower limb with their management.
Methods: The present study extended from April 2006 to
February 2007, in which 65 patients with lower limb
vascular injury were examined in Emergency Department
and Forensic Medicine Department of Tikrit Teaching
Hospital in Salah-Aldin governora
Cervical Uterine Cancer is a disease that explains the vulnerability in which women are in terms of reproductive health with an impact on occupational health and public health, even when in Mexico the prevalence rate is lower than the other member countries of the OECD, its impact on Human Development and Local Development shows the importance that the disease have in communities more than in cities where prevention policies through check-ups and medical examinations seem to curb the trend, but show the lack of opportunities and capacities of health centers in rural areas. To establish the reliability, validity, and correlations between the variables reported in the literature with respect to their weighting in a public hospital. A
... Show MoreThe phenomenon of child labor, any activity performed by a child and represents a contribution to the production, this phenomenon had been rife in Iraqi society, after that the proportion of child labor for the age group (6-14 years) amounting to 3% in 2006, became for the same age group of 8% in 2008*.
It is recognized that each phenomenon reasons, the phenomenon which our atten
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