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.

Application of the network equivalent concept for external system representation for power system transient analysis is well known. However, the challenge to utilize an equivalent network, approximated by a rational function, is to guarantee the passivity of the corresponding model. In this regard, special techniques are required to enforce the passivity of the equivalent model through a post processing approach that minimizes its impact on the original model characteristics. In this paper, the passivity is enforced by expressing the problem in terms of a convex optimization problem that guarantees the global optimal solution. The convex optimization problem is efficiently solved by recently developed numerical interior–point methods. This passivity enforcement is also global which indicates that the passivity enforcement in one region does not lead to passivity violation in other regions.

In recent years and with the growth of the Internet and online social technologies, many questions have been raised regarding the type, quality and extent of social activities in the world based on social networks. Considering the influence of online social networks on recent elections from the year 2009 until now and its following incidents, the present study aims to evaluate the effect of the social capital present in online networks on the citizenship culture of the citizens of Sanandaj. The method of the study was that of a correlational descriptive research and it employed a survey method. The questionnaire was comprised of Dmitri Williams’ standard questions and a researcher-made questionnaire for citizenship culture which had appropriate validity and reliability and was distributed to 400 respondents with the method of multistage cluster sampling. Findings show a medium of the citizenship culture average, and the focus has more been on civic engagement. From the components of civic engagement, the dimensions of attitude and belief were more regarded by the citizens rather than the components of behavior or action. The inferential results also show that the most important dimension of social capital influencing the citizenship culture is the bridging social capital present in the online space.