The self-driven movement of biped robots along an inclined surface is a topic that, despite its inherent complexities, has attracted the attention of many researchers. However, what distinguishes this research from similar works is the consideration of flexibility in the links that constitute such robotic systems. This assumption is not far-fetched, as in the transition phase (impact), the impulse force applied to the system significantly increases the likelihood of exciting vibrational modes. On the other hand, the bones involved in walking are enveloped by muscles, which have viscoelastic properties. Therefore, to achieve more accurate results, modeling the links with viscoelastic properties becomes inevitable. In the discussion of the autonomous movement of bipedal robots, the most important issue is determining the initial configuration of the robot so that the system can perform a periodic and stable motion solely under the influence of gravitational attraction. The highly unstable nature of the system under study, along with the vibrations created by the impact force resulting from the foot striking the inclined surface, constitutes one of the very serious challenges in the progress of this research. Nevertheless, this paper overcomes these challenges by presenting a completely systematic method with very strong mathematical frameworks. Finally, the effect of the intrinsic parameters of elastic links, including the modulus of elasticity and the Kelvin-Voigt coefficient, on the stability of the movement of such robotic systems is examined.

In DEA models, it is assumed that the nature of the data in terms of input and output is precisely known, While in real cases some factors can be considered as both input and output, they are called flexible measures. In the proposed models, for evaluating the performance of DMUs with flexible measures, the value of the variables is considered linear. While in real issues many inputs and outputs of DMUs, including flexible variables have nonlinear values. In other words, if the flexible measure is considered as input, its valuation will be decreasing, and if it is considered as output, its valuation will be increasing (for desirable output). In fact, decision makers seek to maximize output and minimize inputs, therefore, in calculating efficiency and also differentiating between DMUs, less value should be considered for higher amount of inputs and more value for higher amount outputs. Several DMUs may be efficient, but one of them consumes less input than other efficient DMUs to maximize output, so according to the model presented in this article, it will get a higher rank in the ranking of DMUs. So, this paper propose a new model to evaluate performance based on data envelopment analysis and a piecewise linear function in the presence of flexible variables which considers the different effect of flexible variables in efficiency evaluation and distinguishes the valuation between flexible variables as inputs and outputs. The proposed model is used to evaluate the efficiency of cement factories listed on the stock exchange.

By review on rhyme knowledge and based on those subjects which are incorporate in rhetoric and verse critique books, one may already find the importance of rhyme and its effectiveness in Persian poetry. Despite of all advantages of rhyme, sometimes there are some limitations in verse and thus poets prefer to sacrifice the meaning for the sake of rhyme. In fact, such passive reaction against restrictions is due to poet’s weakness so that artist poet never sacrifices pure concepts for lexicon and rhyme in such pitfalls. Amidst, Molavi is the greatest poet that such barriers and limitations never compel him to sacrifice meaning for the sake of lexicon and rhyme; but inversely, subconscious intuitive ingenuity of his mind along with bold iconoclasm may raise tumult in rhymed lexicons, which will make any reader or hearer astonished. Author of the present article intends to study on scheme of Molavi’s artistic innovations and normphobic strategies as the place of rhyme in the honored book of Spiritual Couplets.