In this paper, recommended spiral passive micromixer was designed and simulated. spiral design has the potential to create and strengthen the centrifugal force and the secondary flow. A series of simulations were carried out to evaluate the effects of channel width, channel depth, the gap between loops, and flowrate on the micromixer performance. These features impact the contact area of the two fluids and ultimately lead to an increment in the quality of the mixture. In this study, for the flow rate of 25 μl/min and molecular diffusion coefficient of 1×10-10 m2/s, mixing efficiency of more than 90% is achieved after 30 (approximately one-third of the total channel length). Finally, the optimized design fabricated using proposed 3D printing method.

Examples play a significant role at construction and reconstruction of math concepts. Good educational examples like a clear monitor, act as means for connecting learners, teachers and concepts. This study examines math teachers’ perception of examples and how they could be used in the process of teaching a concept. The research method employed in this study was a qualitative survey method. The research population consisted of all high school math teachers of Markazi province in the academic year 89-90 and 75 randomly selected teachers participated as the sample. The results showed that teachers are aware of the necessity of the use of examples, but they do not have sufficient knowledge of educational examples and their example space is not sufficiently developed. Most of the teachers consider examples as useful and necessary tool and as a common understandable language for learners. But it seems that they do not consider theorems, problems, definitions, proofs and reasoning as examples. Teachers pointed out some characteristics for educational examples such as clarity and simplicity, math accuracy, being in accordance with students’ learning ability and being measurable, but a large number of them neglected important characteristics such as generalizability, the availability and richness and power of a math example. Findings also indicated that most of participating teachers used examples in parts of teaching process such as conceptualizing or teaching procedures.

In this research, in order to investigate the effect of the piezoelectric patch which is used as a sensor or actuator in rotating flexible structures such as a helicopter blade, the free vibrations of the rotating rectangular sheet with and without the piezoelectric patch have been presented. First-order shear deformation theory is considered for plate displacement and piezoelectric field. Considering the effect of Coriolis acceleration, centrifugal acceleration and centrifugal in-plane forces, the equations of motion are derived from Hamilton's principle and the electromechanical couple equation is obtained from Maxwell's equation. For piezoelectric, two electrical conditions, open circuit and closed circuit, which are used in sensors and actuators, respectively, have been considered. The equations are discretized with the help of the numerical method of generalized differential squares and the matrices of inertia mass, eccentricity, Coriolis and stiffness matrix are obtained. Natural frequency values for beam and rotating plate have been compared in Abaqus software. Also, the values obtained from the numerical solution in MATLAB have been verified with articles and ABAQUS, which have high accuracy. The effect of parameters such as hub radius, rotation speed, sheet thickness, aspect ratio, piezoelectric patch thickness and applied voltage on the natural frequency of the system has also been investigated.

Plastic hinge properties play a crucial role in predicting the nonlinear response of structural elements. The plastic hinge region of reinforced concrete normal beams has been previously studied experimentally and analytically. The main objective of this research is to evaluate the behavior of the plastic hinge region of reinforced concrete deep beams and its comparison with normal beams through finite element simulation. To do so, ten beams contain six deep beams, and four normal beams, under concentrated and uniformly distributed loading, are investigated. Lengths in the plastic hinge region involving curvature localization, rebar yielding, and concrete crushing zones are studied. The results indicate that the curvature localization zone is not suitable for the prediction of plastic hinge length in reinforced concrete deep beams. Based on the results it can be stated that in simply supported normal beams the concrete crushing zone is focused on the middle span, but in simply supported deep beams by creating a compression strut between loading place and support, the concrete crushing zone spreads along the compression trajectory. The rebar yielding zone of simply supported beams increases as the loading type is changed from the concentrated load at the middle to the uniformly distributed load.

Two experiments were designed to investigate how students use examples and procedures to solve algebra word problems. In the first study the effect of teaching through example and procedure was investigated on the students algebra word problem solving performance.Participants were 73 girl students in their 3rd year of math-physics branch, secondary school. They were randomly assigned to three groups. The first group was instructed by presenting simple examples,the second group by procedure, whereas the third group was instructed by both procedure and simple example. No significant difference was observed in the performance of the three groups. In Experiment 2, three new conditions consisting of complex example, complex and simple examples,and complex example plus procedure were added to two of the conditions in Study 1, namely simple example condition and procedure condition. The 122 participants in Study 2 had similar characteristics to subjects in the first study. Results indicated that there were statistically significant differences among the five groups. Results show that adding examples at different levels of complexity to procedure improves the capability of students problem solving, which is in harmony with empirical and theoretical background.

In this paper, we investigate pseudo-Riemannian manifolds those eigenvalues of the Weyl conformal Jacobi operators are constant on the unit sphere bundles. Using a result of [4], we give an explicit construction of conformally Osserman manifold which is not locally conformally flat.

There have been various studies on Hafiz’s poetry. Pleasant rhythms, fascinating rhymes, appropriate lexicon, deep meanings, mystical allusions, and wise sayings of his poetry have been appreciated yet a lot of not pondered upon and the path for scholars is still not paved. This witticism in expressing delicate ideas and fine emotions is one of those areas which is considered by only few cynics. This article is an attempt to provide a study of the beautiful and splendid heap of Hafiz’s poetry.

There have been various studies on Hafiz’s poetry. Pleasant rhythms, fascinating rhymes, appropriate lexicon, deep meanings, mystical allusions, and wise sayings of his poetry have been appreciated yet a lot of not pondered upon and the path for scholars is still not paved. This witticism in expressing delicate ideas and fine emotions is one of those areas which is considered by only few cynics. This article is an attempt to provide a study of the beautiful and splendid heap of Hafiz’s poetry.