• Advanced engine flows and combustion

      Peng, Zhijun; Megaritis, Thanos; Sung, Chih-Jen; Yaga, Minoru; Hellier, Paul; Tian, Guohong; University of Bedfordshire; Brunel University; University of Connecticut; University of the Ryukyus; et al. (Hindawi, 2017-08-07)
      The transport sector accounts for a significant part of carbon emissions worldwide, and so the need to mitigate the greenhouse effect of CO2 from fossil fuel combustion, and to reduce vehicle exhaust emissions has been the primary driver for developing cleaner and more efficient vehicle powertrains, and environmentally friendly fuels.  As alternatives to combustion engines have yet to overcome technical challenges to attain significant utilisation in the transport sector, piston-driven internal combustion engines and gas turbine aero-engines remain very attractive powertrain options due to their high thermal efficiency. Meanwhile, since the introduction of various emissions standards, that have forced the employment of various aftertreatment systems, the evolution of combustion process has been significant. Advanced combustion strategies have attempted to find in-chamber approaches to either meet these emission standards fully and thus avoid the need to use aftertreatment, or at the very least, to lower the performance demands required from aftertreatment systems and thus reducing their cost and complexity. While the main focus of combustion system development has been recently to lower emissions of CO2, there is also significant interest to lower nitric oxides (NOx) and particulate matter (PM) emissions and other harmful emissions.
    • Effects of injection rate profile on combustion process and emissions in a diesel engine

      Bai, Fuqiang; Zhang, Zuowei; Du, Yongchen; Zhang, Fan; Peng, Zhijun; Tianjin University; University of Hertfordshire; University of Bedfordshire (Hindawi, 2017-06-21)
      When multi-injection is implemented in diesel engine via high pressure common-rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid and wedge) of injection rate profiles were investigated. Modelling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline - rectangle (flat) shape of injection rate can have better balance between NOx and soot emissions than other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces highest soot emissions among five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions was produced by triangle shape due to higher peak injection rate.
    • Millimetre-wave antennas and systems for the future 5G

      Ur-Rehman, Masood; Abbasi, Qammer Hussain; Rahman, Atiqur; Khan, Imdad; Chattha, Hassan Tariq; Abdul Matin, Mohammad; University of Bedfordshire; Texas A & M University at Qatar; University of Glasgow; North South University, Dhaka; et al. (Hindawi, 2017-04-10)
      Editorial of the special issue on Millimetre-Wave Antennas and Systems for the Future 5G
    • Multiband split-ring resonator based planar inverted-F antenna for 5G applications

      Ishfaq, Muhammad Kamran; Rahman, Tharek Abd; Chattha, Hassan Tariq; Ur-Rehman, Masood; Universiti Teknologi Malaysia; Government College University, Faisalabad; Islamic University in Madinah; University of Bedfordshire (Hindawi, 2017-03-21)
      5G, the fifth generation of wireless communications, is focusing on multiple frequency bands, such as 6GHz, 10GHz, 15GHz, 28GHz, and 38GHz, to achieve high data rates up to 10 Gbps or more.The industry demands multiband antennas to cover these distant frequency bands, which is a task much more challenging. In this paper, we have designed a novel multiband split-ring resonator (SRR) based planar inverted-F antenna (PIFA) for 5G applications. It is composed of a PIFA, an inverted-L parasitic element, a rectangular shaped parasitic element, and a split-ring resonator (SRR) etched on the top plate of the PIFA.The basic PIFA structure resonates at 6GHz. An addition of a rectangular shaped parasitic element produces a resonance at 15GHz. The introduction of a split-ring resonator produces a band notch at 8GHz, and a resonance at 10GHz, while the insertion of an inverted-L shaped parasitic element further enhances the impedance bandwidth in the 10GHz band. The frequency bands covered, each with more than 1GHz impedance bandwidth, are 6GHz (5–7GHz), 10GHz (9–10.8GHz), and 15GHz (14-15GHz), expected for inclusion in next-generation wireless communications, that is, 5G. The design is simulated using Ansys Electromagnetic Suite 17 simulation software package.The simulated and the measured results are compared and analyzed which are generally in good agreement.