A survey on OFDM-based elastic core optical networking

Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed

Simulation and modeling of the behavior in the four-stroke spark ignition engine by using CFD simulation

Computational fluid dynamics (CFD) is a branch of fluid mechanics that use numerical analysis and data structures to analyze and solves problems that involve fluid flows. CFD have been applied to a wide range of research and engineering problems in many fields of study and industries, including engine and combustion analysis. The objective of this review paper is to analyze the behavior in the four-stroke Spark Ignition (SI) engine by using CFD simulation. To get the require result a few methods have been used to analyze the behavior in the engine such as using CAD geometric model where the solid works software have been prepared. Then, in the CAD geometric model also have ANSYS software to perform analysis in engine module. To predict the behavior of the engine during its working two type of analysis can be performed namely port flow simulation and combustion simulation. So, in first part of this report, the CFD analysis is carried out to analyze the performance parameter, including intake stroke, compression stroke, power stroke and exhaust stroke with hexane fuel combustion. For the results, some details of the engine model and some predicted results including temperature, flow time and pressure profiles. With the existence of CFD simulation it can help many fields of study and industries by predict and analyze the possibility that can be happened in the future. At the same time, serves as a quick and economical way of future engine designs and concepts