مطالب مرتبط با کلیدواژه

Symmetry


۱.

Does Really Lower Limbs Behave Asymmetric in Gait of People Without Impairments(مقاله علمی وزارت علوم)

نویسنده:

کلیدواژه‌ها: Biomechanics Gait Symmetry

حوزه های تخصصی:
تعداد بازدید : ۱۱۷۶ تعداد دانلود : ۵۴۰
Using two consecutive gait cycles، simultaneous and bilateral kinetic gait data، the main objectives of this study were a) to identify the main functional roles of ankle، knee and hip extensors/flexors، and b) to determine whether the action taken by these muscle groups appears to be symmetric or not. Gait of our able-bodied subjects appears to be asymmetric with significant differences noted between each two corresponding peak muscle moment values. Using Principal Component Analysis (PCA) as a curve structure detection method، task discrepancies were recognized when comparisons were made between each two corresponding representative moment curves at each joint (local asymmetry). Muscle moment behaved symmetrically when the right limb representative curve was compared to its corresponding principal component (PC) at the contralateral limb. Gait of able-bodied subjects appears to be symmetric، while control and propulsion were recognized as two major roles of the extensors and flexors (global gait asymmetry). Symmetrical behavior of the lower limbs should be considered a consequence of local asymmetry which indicates different levels of within and between muscle activities developed at each joint during gait cycles
۲.

Comparison of Kinematics and kinetics Symmetry of Lower Limbs during running(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Running Symmetry moment angle Biomechanics

حوزه های تخصصی:
تعداد بازدید : ۱۳۹ تعداد دانلود : ۹۶
Aim and background: The aim of this study was to investigate Kinematics and kinetics Symmetry of Lower Limbs during running at a constant speed. Methods: 28 Elite runner (age: 34.75±6.63years) participated in this study. Running at constant speed was conducted by each subject at 2/5 m.s-1 on treadmill while kinematic and kinetic data were captured at 150 Hz and 300 Hz, respectively. The peak of joint moments and flexion angles in sagittal plane were calculated. The normality and homogeneity of variances assumptions of the dependent variables was tested using Bartlett and Leven’s test. Independent t tests were conducted to examine the symmetry of hip, knee and ankle moments between dominant and non-dominant joints during stance phase of running (p<0.05). Results: results of the present study showed no significant difference exists between dominant and non-dominant lower joints regarding the peak moments of Hip, Knee and ankle in sagittal plane during stance phase (p>0.05) as well as between peak flexion angles during running. Conclusion: Symmetry exists in lower joints sagittal moments and flexion angle during running at the constant speed. According to the results dominant and non- dominant lower joints play propulsive and absorbent roles cooperatively.
۳.

The Study of Jahangir Dome and Guriye Stucco Decorations: With an Emphasis on Applied Geometry(مقاله علمی وزارت علوم)

کلیدواژه‌ها: Sasanian Stucco Symmetry repetition Geometric

حوزه های تخصصی:
تعداد بازدید : ۱۵ تعداد دانلود : ۱۷
This paper tries to survey the use of geometric patterns in stucco decorations as an important identity and cultural element in the Sasanian era building designs. Seven frieze patterns were used in order to understand the practical geometry in Sasanian stucco. The studied stuccoes were found during archaeological excavations conducted between 2015 and 2017 at e Jahangir Dome and Guriye Stuccos in Eivan, Ilam province. In this article, the discovered stuccoes have been examined, results of which indicate that stuccoes can be divided into three categories based on their features and applications: geometric patterns, vegetal patterns, and animal patterns. Comparing these stuccoes with those found elsewhere such as Qale Yazdegerd, and Ctesiphon shows that the buildings of Jahangir Dome and Guriye were noble houses in the Sasanian period, with their vegetal motifs and mythological animals being e formed under the influence of religious and ritual elements. The survey of motifs on the base with seven frieze patterns shows artists’ adherence to the principle of symmetry and repetition.