Nitinol (NiTi) is used in many medical applications, including hard tissue replacements, because of its suitable characteristics, including a close elastic modulus to that of bones. Due to the great importance of the mechanical properties of this material in tissue replacements, this work aims to study the hysteresis response in an attempt to explore the ability of the material to remember its previous mechanical state in addition to its ability to withstand stress and to obtain the optimal dimensions and specifications for the manufacturer of NiTi actuators. Stress-strain examination is done in a computational way using a mutable Lagoudas MATLAB code for various coil radii, environment temperatures, and coil lengths. The computational methodology was done by varying the dimensions and the ambient temperature of the simulated NiTi spring actuator. The hysteresis loop is studied by increasing the external stress for a reversible martensitic transformation. The coil radius, spring height, and wire radius affect the spring force and deformations. In the same way, these parameters affect the strain and stress point values. These changes are shown through the martensite and austenite start and finish values. The NiTi hysteresis loop narrows with increasing ambient temperature or initial spring height. At a higher temperature, the force supplied to the actuator must be less for the same deformation; therefore, a higher ambient temperature provides more efficiency for the shape memory devices and a longer lifetime for the actuator.
In front of the serious deterioration of the elements of the environment, new convictions arose the need to integrate into the global environmental concerns as being one and the issue of shared responsibility and the impact of this conviction, the evolution of the environment protection law in many countries, including Algeria. Due to the multiplicity of perceptions about the environmental result of multiple scientific disciplines, the legislative concept emerged to protect the environment, which includes prevention and rational management and conservation and restoration and repair.
Environmental planning for the various governments and countries aims to avert disasters and achieve the
... Show MoreObjectives. This study aimed at finding out whether anterior teeth angulation and inclination have a relationship with the maxillary teeth and dental arch dimensions. Methods. Fifty study models with normal occlusion were selected from the archive of the Department of Orthodontics at Baghdad Dental Faculty. Maxillary dental arch width and length at different points were determined in addition to measuring anterior teeth angulation, inclination, crown thickness, overjet, overbite, and Bolton’s ratios. The unpaired t-test and Pearson’s correlation coefficient test were used for data analysis. Results. No statistical gender differences were reported in all measurements except the dental arch widths and length where males had signif
... Show MoreThe research aims to show the dimensions of organizational trust represented by (administrative policies opportunities for innovation and self innovation and self- realization,availability of information,prevailing organizational values) and its reiationship to achieving the strategic position of banks represented by formation of expectations,buiiding networks,learning operations As the research was applied in each of the banks (middle east)Iraqi investment,Al-Ahly Iraqi, Business Bay, Al- Mansour investment bank),the qusestionnaire was adopted as a tool to collect data and information from the sample number (138)who are in the site (department director, division ,M.division director ,division officer, unit officer)the statistica
... Show MoreExperimental work was carried out to investigate the effect of fire flame (high temperature) on specimens of one way slabs using Self Compacted Concrete (SCC). By using furnace manufactured for this purpose, twenty one reinforced concrete slab specimens were exposed to direct fire flame. All of specimens have the same dimensions. The slab specimens were cooled in two types, gradually by left them in the air and suddenly by using water. After that the specimens were tested under two point loads, to study, the effect of
different: temperature levels (300ºC, 500ºC and 700ºC), and cooling rate (gradually and sudden cooling conditions) on the concrete compressive strength, modulus of rupture, flexural strength and the behavior of reinf
The present study develops the sorption model for simulating the effects of pH and temperature on the uptake of cadmium from contaminated water using waste foundry sand (WFS) by allowing the variation of the maximum adsorption capacity and affinity constant. The presence of two acidic functional groups with the same or different affinity is the basis in the derivation of the two models; Model 1 and Model 2 respectively. The developed Bi-Langmuir model with different affinity (Model 2) has a remarkable ability in the description of process under consideration with coefficient of determination > 0.9838 and sum of squared error < 0.08514. This result is proved by FTIR test where the weak acids responsible of cadmium ions removal
... Show MoreThe purpose of this study is to compare the influence of three teaching methods, as represented by problem-based learning (PBL), the PBL with lecture method, and the conventional teaching on undergraduate physics students' group work skills among bachelor’s degree physics students. In this study, the pre- and post-test were done and the instruments were administered to the students for data collection. The actual sample size comprises of 122 students, who were selected randomly from the physics department, college of education in iraq. Overall, the statistical results rejected null hypothesis of this study. Thus, using the PBL without or with lecture method enhances the skills of the group work among the bachelor’s degree physics studen
... Show MoreAfrican countries are among the countries in the world that suffer from the phenomenon of child recruitment in wars and conflicts. There are many reasons behind it, including the nature of the human formation of children, the societal violence to which they are exposed, lack of access to education, economic hardships, as well as the role of African wars and conflicts and other reasons that compelled children to join armed groups and participate in military operations. The recruitment of children is divided into two types, compulsory and voluntary, and this leads to many humanitarian and security repercussions that are not limited to a specific period of time but extend to subsequent generations, and due to its seriousness, t
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