Iran University of Science and Technology

About: Iran University of Science and Technology is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Nonlinear system & Finite element method. The organization has 12917 authors who have published 24965 publications receiving 372013 citations. The organization is also known as: Governmental Technical Institute & Advanced Art College.

The influence of fuel composition on the combustion and emission characteristics of natural gas fueled engines

Abstract: As global energy demand rises, natural gas (NG) plays an important strategic role in energy supply. Natural gas is the cleanest fossil fuel that has been investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. This paper reviews the research on the effects of natural gas composition on combustion and emission characteristics of natural gas fueled internal combustion engines (ICEs) and reports the most achievements obtained by researchers in this field. It has been reported that the engine performance and emission are greatly affected by varying compositions of natural gas. The most important NG fuel property is the Wobbe number (WN). Generally, it was agreed by researchers that the fuels with higher hydrocarbons, higher WN, and higher energy content exhibited better fuel economy and carbon dioxide (CO2) emissions. Nitrogen oxides (NOx) emissions were also increased for gases with higher levels of higher WN, while total hydrocarbons (THCs), carbon monoxide (CO), showed some reductions for these gases. On the other hand, particulate matter (PM) emissions did not show any fuel effects. Moreover, adding of small fractions of higher alkanes, such as ethane and propane, significantly improved ignition qualities of natural gas engines. The results presented provide a good insight for researchers to pursue their future research on natural gas fueled ICEs.

A Novel Low-Cost Circularly Polarized Rotated Stacked Dielectric Resonator Antenna

Abstract: A novel low-cost method for generating circular polarization in a dielectric resonator antenna is proposed. The antenna comprises four rectangular dielectric layers, each one being rotated by an angle of 30 ° relative to its adjacent layers. Utilizing such an approach has provided a circular polarization over a bandwidth of 6% from 9.55 to 10.15 GHz. This has been achieved in conjunction with a 21% impedance-matching bandwidth over the same frequency range. Also, the radiation efficiency of the proposed circularly polarized dielectric resonator antenna is 93% in this frequency band of operation