Circular economy as a challenging issue in social innovation area, more specifically with a focus on sustainable development, and in response to current global challenges regarding, warming, resource scarcity, attention to the environment as well as the presentation of an economic model aimed at eliminating the direct link between economic development and resource use, has been widely discussed by researchers, experts and policymakers as one of the world’, s trends. However, the concept of Circular economy as a macro concept is still developing. In addition, many experts have considered the explanation of the Circular economy concept to be dependent on the context of its emergence, but there is few documented research that has examined this concept in the context of innovation ecosystems. The present study tries to describe the implementation of Circular innovation ecosystem with the aim of conceptualizing the Circular economy in the innovation ecosystem using previous sources and experts ’, opinions. Therefore, this study, using a hybrid approach and through methods such as )1( systematic review aiming at extracting previous data, )2(content analysis aiming at examining the opinion of experts, presents the infrastructure, strategies, programs, and requirements for establishing a Circular innovation ecosystem. This research stands out for a general question of what is the fundamental strategies of Circular economy in implementation of Circular innovation ecosystems. The results of this research will bring achievements for a wide range of researchers, policymakers in various fields, economic activists as well as institutions in charge of sustainable development.

The generation of shock waves and their repercussions in high-speed vehicles are inevitable. Particularly, the hot plume from the aircraft exhaust ejecting at a high speed, as well as the emitted aeroacoustic noise, have several consequences. Besides, the occurrence of the supersonic core length and the emission of high screech noise are mostly due to the shock cells, prevailing in high-speed jets. Therefore, understanding the shock cell structures developed at the exit of aircraft or rocket nozzles is vital in improving mixing and thereby the noise characteristics. Essentially, non-Circular nozzle shapes are well known for enhancing entrainment characteristics and mitigating the noise due to their differential spreading over the nozzle's perimeter. The current study examines the shock structures of Circular, elliptic, and square jets at various sonic underexpansion levels. In this investigation, the nozzle geometries are considered to have the same exit area. The Nozzle Pressure Ratio (NPR) was adjusted to 3, 4, and 5 to achieve moderate and highly underexpansion conditions. The shadowgraph visualization method is used to study the development of shock cells from axisymmetric and asymmetric nozzles. It is interesting to observe that the incident and reflected shock structures exist only at moderate and high underexpansion levels. Besides, the elliptic and the square jets have distinctive flow patterns along their different axis planes. The intercepting shock appears on the elliptic jet in the minor axis rather than the major axis direction. The curvature of the intercepting shock wave was found to be greater for the elliptic jet than that for the Circular jet. In addition, the square jet in the symmetry plane diverges from the jet centerline, but the jet in the diagonal direction converges. Moreover, the estimated shock cell lengths using shadowgraph images were compared to a theoretical model where the experimentally obtained results are in good agreement with the theoretical values.

Energy absorbers are used to store undesirable energy. Thin walled tubes are one of the most common energy absorbing components in. In this paper energy absorption of aluminum tubes with circumferential pattern is investigated. The pattern with different wave length and amplitude is made on the tube’ s wall. Then, using numerical simulation, static energy absorbing characteristics of different tubes are investigated. The goal is to study the effect of pattern geometry on tube’ s energy absorbing characteristics. Findings show that in some parameters related to energy absorption, the values for tubes with and without pattern are somewhat similar. However, generally speaking results show that producing patterns with certain geometrical properties can considerably increase the capacity of tubes in energy absorption.

This paper presents the application of the generalized differential quadrature (GDQ) method for the hydrodynamic analysis of Circular and nonCircular, two lobe and three lobe, journal bearings. GDQ is a simple, efficient, high-order numerical technique and it uses the information on all grid points to approach the derivatives of the unknown function. The effectiveness of the solution technique is verified by comparing the GDQ computed results with that of analytical solutions and FDM results from the published literature. It is found that GDQ method can easily compete with the existing methods of solution of lubrication problems for its analytical simplicity, smaller computer storage requirements and capability of producing accurate results with very high computational efficiency. Also the effects of design and assemble parameters, namely the eccentricity ratio, preload factor, mount and tilt angles on the performance parameters of these bearings have been investigated using GDQ method. Results show that the variation of mount and tilt angles can has variable effects on nonCircular lobed journal bearing performance parameters. Among the two types of nonCircular bearings considered, the effect of the mount and tilt angles is more significant for two lobe bearings in comparison with the three lobe bearings.

In this paper a new kind of coupled lines called Circular symmetric coupled microstrip transmission lines is introduced. At first the capacitance C and inductance L matrices of this kind of microstrip lines are determined by solving the laplace’s equation using fourier series method. Then by some examples the capacitance C and inductance L matrices of this kind of microstrip lines are discussed.

Neighbour effects, that is the response on a given plot is affected by the treatments in neighbouring plot and the effect by the treatment applied to that plot. As a result, the estimate of treatment differences may deviate because of this interference from neighbouring plots. Neighbour-balanced designs ensure that the treatment comparisons will be as little affected by neighbour effects as possible.Circular neighbour-balanced design are divided into two groups. In the previouse researches, method of cyclic shifts to construct CNB1 has been used, the authors used this method to construct CNB2. Some series of CNB2 are found by computer programming using in MATLAB software and method of cyclic shifts. Then, some of these designs witch are universally optimal under models with one sided neighbour effect (M1) are identified.