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.
The mobile phone is widespread all over the world. This technology is one of the most widespread with more than five billion subscriptions making people describe this interaction system as Wireless Intelligence. Mobile phone networks become the focus of attention of researchers, organizations and governments due to its penetration in all life fields. Analyzing mobile phone traces allows describing human mobility with accuracy as never done before. The main objective in this contribution is to represent the people density in specific regions at specific duration of time according to raw data (mobile phone traces). This type of spatio-temporal data named CDR (Call Data Records), which have properties of the time and spatial indications for th
... Show MoreObjective(s): To assess parents' attitude toward immunization and its relation with their compliance and to find out the relationship between parents' attitude and their socio-demographic characteristics.
Methodology: A descriptive design is conducted from the period of 19th September 2020 to the 6th of March 2021. A non-probability (convenient) sample of (292) parents was selected from (5) primary health care centers in Karbala city. These centers are distributed throughout (2) primary health care sectors selected randomly as (20%) from each sectors. The questionnaire is developed and composed of three parts: First part: parent's socio-demographic characteristics, Second part: parents' attitude domain, which involves (13 items), and
Numerical study is adapted to combine between piezoelectric fan as a turbulent air flow generator and perforated finned heat sinks. A single piezoelectric fan with different tip amplitudes placed eccentrically at the duct entrance. The problem of solid and perforated finned heat sinks is solved and analyzed numerically by using Ansys 17.2 fluent, and solving three dimensional energy and Navier–Stokes equations that set with RNG based k−ε scalable wall function turbulent model. Finite volume algorithm is used to solve both phases of solid and fluid. Calculations are done for three values of piezoelectric fan amplitudes 25 mm, 30 mm, and 40 mm, respectively. Results of this numerical study are compared with previous b
... Show MoreThe research (Anthropology and Representations of magic in Arab Theatrical Text, Harut and Marut's play as a Model) is concerned with studying magic and the forms of its presence in the theatrical text in different human cultures where it belongs. The research consists of four chapters.
The first chapter includes the research problem that revolves around the following questions: (what is the mechanism of employing magic anthropology and its representations in the Arab theatrical text Harut and Marut's play as a model?), and the research importance which is attributed to the necessity of studying (magic) in the Arab theatrical text as it is considered the inauguration of one of the social phenomena that many researchers in the field o
Objective: Per-implantitis is one of the implant treatment complications. Dentists have failed to restore damaged periodontium by using conventional therapies. Tissue engineering (stem cells, scaffold and growth factors) aims to reconstruct natural tissues. The paper aimed to isolate both periodontal ligament stem cells (PDLSCs) and bone marrow mesenchymal stem cells (BMMSCs) and use them in a co-culture method to create three-layered cell sheets for reconstructing natural periodontal ligament (PDL) tissue. Materials and methods: BMMSCs were isolated from rabbit tibia and femur, and PDLSC culture was established from the lower right incisor. The cells were co-cultured to induce BMMSC differentiation into PDL cells. Cell morphology, stem cel
... Show MoreThe movement and broadening of foreign and European words into Persian is a topic within historical linguistics. Such changes are semantic, phonological
Since many of these European loanwords into Persian took a remarkable space within Persian dictionaries, and became an indispensible part of the language, a study of the original languages of these loanwords may identify the enormous effect of those languages upon Persian, being a receptor language, and may refer to the liveliness.
Among the important factors which helped the movement of various loanwords into Persian are:
- Geographical: this is seen via contact between Persian people and those neighboring people, specifically those speaking Ara