• 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.
    • Advances in body-centric wireless communication: applications and state-of-the-art

      Abbasi, Qammer Hussain; Ur-Rehman, Masood; Alomainy, Akram; Qaraqe, Khalid (The IET, 2016-06-01)
    • Analysis of sub-channel correlation in dual-polarised MIMO systems via a polarisation diversity scheme

      Fang, Cheng; Liu, Enjie; Ur-Rehman, Masood; University of Bedfordshire (IEEE, 2017-02-23)
    • Antennas for global navigation satellite systems

      Chen, Xiaodong; Parini, Clive G.; Collins, Brian; Yao, Yuan; Ur-Rehman, Masood (Wiley, 2012-03-01)
    • Antireflection silicon structures with hydrophobic property fabricated by three-beam laser interference

      Zhao, Le; Wang, Zuobin; Zhang, J.; Cao, L.; Li, L.; Yue, Y.; Li, Dayou; Changchun University of Science and Technology; University of Bedfordshire; Jiaotong-Liverpool University (Elsevier, 2015-08-15)
      This paper demonstrates antireflective structures on silicon wafer surfaces with hydrophobic property fabricated by three-beam laser interference. In this work, a three-beam laser interference system was set up to generate periodic micro-nano hole structures with hexagonal distributions. Compared with the existing technologies, the array of hexagonally-distributed hole structures fabricated by three-beam laser interference reveals a design guideline to achieve considerably low solar-weighted reflectance (SWR) in the wavelength range of 300-780 nm. The resulting periodic hexagonally-distributed hole structures have shown extremely low SWR (1.86%) and relatively large contact angle (140°) providing with a self-cleaning capability on the solar cell surface.
    • Application of water quality index for pollution detection at Luton Hoo lake

      Anyachebelu, Tochukwu Kene; Conrad, Marc; Rawson, David M.; Ajmal, Tahmina; University of Bedfordshire (IEEE, 2016-01-07)
      This study investigated contamination problems through physical and chemical surface water monitoring. The physical parameters were temperature, conductivity and turbidity while the chemical parameters were dissolved oxygen, pH and ammonium. These parameters were measured at two locations on the lake to monitor the water quality and possible sources of contamination. We evaluated the relationship of the measured parameters to contamination sources and its effect on the water quality. The collected data from the installed multi parameter sensors were analyzed to assess the difference in values at the different sensor locations based on a water quality index.
    • Asymmetric transport of light in linearly arrayed metallic nano-particles

      Aroua, Walid; Horchani, R.; AbdelMalek, Fathi; Haxha, Shyqyri; Kamli, Ali A.; National Institute of Applied Science and Technology, Tunisia; Dhofar University; University of Bedfordshire; Jazan University, Saudi Arabia (Springer, 2016-09-15)
      A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.
    • Authentication in millimeter-wave body-centric networks through wireless channel characterization

      Zhao, Nan; Zhang, Zhiya; Ur-Rehman, Masood; Ren, Aifeng; Yang, Xiaodong; Zhao, Jianxun; Zhao, Wei; Dong, Binbin; Xidian University; University of Bedfordshire (IEEE, 2017-11-13)
      Advent of 5G technologies has ensued in massive growth of body-centric communications (BCC), especially at millimeter-wave frequencies. As a result, the portable/handheld terminals are becoming more and more “intelligent” but not without the cost of being less secure. Improved authentication measures need to be explored, as effective identity authentication is the first level of security in these devices. This paper presents a novel keyless authentication method exploiting wireless channel characteristics. Human palm has distinct transmission coefficient (S21) for each of the users and is used for in-vivo fingerprint identification in this work. A detailed channel modeling using data acquisition from real environment and empirical approach is adopted to evaluate the usability of this method. The results show that this method can provide a secure operation for the millimeter-wave 5G BCCs.
    • Automated ontology framework for service robots

      Kanjaruek, Saranya; Li, Dayou; Qiu, Renxi; Boonsim, Noppakun; University of Bedfordshire (Institute of Electrical and Electronics Engineers Inc., 2016-02-25)
      This paper presents an automated ontology framework for service robots. The framework is designed to automatically create an ontology and an instance of concept in dynamic environment. Ontology learning from text is applied to build a concept hierarchy using WordNet which provides a rich semantic processing for physical objects. The Automated Ontology is composed of four modules: Concept Creation, Property Creation, Relationship Creation and Instance of Concept Creation. The automated ontology algorithm was implemented in order to create the concept hierarchy in the Robot Ontology. The Semantic Knowledge Acquisition represents knowledge of physical objects in dynamic environments. In simulation experiments, the list of object names and property names was identified. The result shows the concept hierarchy which represents explicit terms and the semantic knowledge of physical objects for performing everyday manipulation tasks.
    • Baseline and triangulation geometry in a standard plenoptic camera

      Hahne, Christopher; Aggoun, Amar; Velisavljević, Vladan; Fiebig, Susanne; Pesch, Matthias (Springer, 2017-09-22)
      In this paper, we demonstrate light field triangulation to determine depth distances and baselines in a plenoptic camera. The advancement of micro lenses and image sensors enabled plenoptic cameras to capture a scene from different viewpoints with sufficient spatial resolution. While object distances can be inferred from disparities in a stereo viewpoint pair using triangulation, this concept remains ambiguous when applied in case of plenoptic cameras. We present a geometrical light field model allowing the triangulation to be applied to a plenoptic camera in order to predict object distances or to specify baselines as desired. It is shown that distance estimates from our novel method match those of real objects placed in front of the camera. Additional benchmark tests with an optical design software further validate the model’s accuracy with deviations of less than 0:33 % for several main lens types and focus settings. A variety of applications in the automotive and robotics field can benefit from this estimation model.
    • Broadband antennas

      Zhang, Zhiya; Ur-Rehman, Masood; Yang, Xiaodong; Serpedin, Erchin; Ren, Aifeng; Zuo, Shaoli; Rahman, Atiqur; Abbasi, Qammer Hussain (IGI Global, 2015-08-01)
    • Capture and sorting of multiple cells by polarization-controlled three-beam interference

      Hou, Yu; Wang, Zuobin; Hu, Yaowei; Li, Dayou; Qiu, Renxi; Changchun University of Science and Technology; University of Bedfordshire (IOP PUBLISHING LTD, 2016-02-02)
      For the capture and sorting of multiple cells, a sensitive and highly efficient polarization-controlled three-beam interference set-up has been developed. With the theory of superposition of three beams, simulations on the influence of polarization angle upon the intensity distribution and the laser gradient force change with different polarization angles have been carried out. By controlling the polarization angle of the beams, various intensity distributions and different sizes of dots are obtained. We have experimentally observed multiple optical tweezers and the sorting of cells with different polarization angles, which are in accordance with the theoretical analysis. The experimental results have shown that the polarization angle affects the shapes and feature sizes of the interference patterns and the trapping force.
    • Cellular shear adhesion force measurement and simultaneous imaging by atomic force microscope

      Hou, Yu; Wang, Zuobin; Li, Dayou; Qiu, Renxi; Li, Yan; Jiang, Jinlan; Changchun University of Science and Technology; Chinses Academy of Sciences; University of Bedfordshire; Jilin University (Springer, 2017-01-06)
      This paper presents a sensitive and fast cellular shear adhesion force measurement method using an atomic force microscope (AFM). In the work, the AFM was used both as a tool for the imaging of cells on the nano-scale and as a force sensor for the measurement of the shear adhesion force between the cell and the substrate. After the cell imaging, the measurement of cellular shear adhesion forces was made based on the different positions of the cell on the nano-scale. Moreover, different pushing speeds of probe and various locations of cells were used in experiments to study their influences. In this study, the measurement of the cell adhesion in the upper portion of the cell is different from that in the lower portion. It may reveal that the cancer cells have the metastasis tendency after cultured for 16 to 20 hours, which is significant for preventing metastasis in the patients diagnosed with early cancer lesions. Furthermore, the cellular shear adhesion forces of two types of living cancer cells were obtained based on the measurements of AFM cantilever deflections in the torsional and vertical directions. The results demonstrate that the shear adhesion force of cancer cells is twice as much as the same type of cancer cells with TRAIL. The method can also provide a way for the measurement of the cellular shear adhesion force between the cell and the substrate, and for the simultaneous exploration of cells using the AFM imaging and manipulation
    • Characteristics of near-nozzle spray development from a fouled GDI injector

      Zhou, Jianwei; Pei, Yiqiang; Peng, Zhijun; Zhang, Yanfeng; Qin, Jing; Wang, Li; Liu, Changwen; Zhang, Xiaoyu; Tianjin University; University of Bedfordshire; et al. (Elsevier Ltd, 2018-03-16)
      The near-nozzle spray development of a typical fouled gasoline direct injection (GDI) injector was investigated. The fouled injector had been used in a stratified-charge combustion GDI engine and showed typical characteristics, such as accumulated deposits inside and around the nozzles and a reduced flow rate of 2.9–5.7%. Back-illumination and Mie-scattering methods were employed in spray experiments, in conjunction with a high speed camera and a macro lens, to assess the near-nozzle spray behaviors. The experimental results show that at all injection pressures tested, the interaction between deposits and spray led to several poor spray behaviors during the full injection evolution, including spray distortion, residual fuel storage in the nozzles and deposits layer, liquid splashing, the formation of ligament and large droplets and tip wetting/dripping. These effects all may result in high soot emissions. The after-injection stage of the fouled injector produced more liquid ligaments than that of the new injector. It was also found that high injection pressures did not improve atomization during after-injection, nor reduce the amounts of ligaments and droplet clusters beyond the main spray boundary. The plume width and projected spray area of a single nozzle in the fouled injector were decreased by 5–7% and 17–20%, respectively, due to fuel flow losses. The delays in the start of injection and end of injection were approximately 20 μs and 30–40 μs, respectively.
    • A closed-loop reciprocity calibration method for massive MIMO in terrestrial broadcasting systems

      Luo, Hua; Zhang, Yue; Huan, Li-Ke; Cosmas, John; Aggoun, Amar; University of Bedfordshire; Brunel University; Cobham Wireless (IEEE, 2016-09-22)
      Massive multi-input multioutput (MIMO) is believed to be an effective technique for future terrestrial broadcasting systems. Reciprocity calibration is one of the major practical challenges for massive MIMO systems operating in time-division duplexing mode. A new closed-loop reciprocity calibration method is investigated in this paper which can support online calibration with a higher accuracy compared to the existing methods. In the first part of the proposed method, an optimized relative calibration is introduced using the same structure of traditional relative calibration, but with less impaired hardware in the reference radio chain. In the second part, a test device (TD)-based calibration is proposed which makes online calibration possible. An experiment setup is built for the measurement of the base station hardware impairments and TD-based calibration implementation. Simulation results and the error vector magnitude of UE received signal after calibration show that the performance of our proposed method is improved significantly compared to the existing relative calibration methods.
    • Convexity characterization of virtual view reconstruction error in multi-view imaging

      Velisavljević, Vladan; Dorea, Camilo; Chakareski, Jacob; de Queiroz, Ricardo (IEEE, 2017-09-22)
      Virtual view synthesis is a key component of multi-view imaging systems that enable visual immersion environments for emerging applications, e.g., virtual reality and 360-degree video. Using a small collection of captured reference viewpoints, this technique reconstructs any view of a remote scene of interest navigated by a user, to enhance the perceived immersion experience. We carry out a convexity characterization analysis of the virtual view reconstruction error that is caused by compression of the captured multi-view content. This error is expressed as a function of the virtual viewpoint coordinate relative to the captured reference viewpoints. We derive fundamental insights about the nature of this dependency and formulate a prediction framework that is able to accurately predict the specific dependency shape, convex or concave, for given reference views, multi-view content and compression settings. We are able to integrate our analysis into a proof-of-concept coding framework and demonstrate considerable benefits over a baseline approach.
    • Cooled solar PV panels for output energy efficiency optimisation

      Peng, Zhijun; Herfatmanesh, Mohammad R.; Liu, Yiming; University of Bedfordshire; University of Hertfordshire (Elsevier, 2017-07-10)
      As working temperature plays a critical role in influencing solar PV’s electrical output and efficacy, it is necessary to examine possible way for maintaining the appropriate temperature for solar panels. This research is aiming to investigate practical effects of solar PV surface temperature on output performance, in particular efficiency. Experimental works were carried out under different radiation condition for exploring the variation of the output voltage, current, output power and efficiency. After that, the cooling test was conducted to find how much efficiency improvement can be achieved with the cooling condition. As test results show the efficiency of solar PV can have an increasing rate of 47% with the cooled condition, a cooling system is proposed for possible system setup of residential solar PV application. The system performance and life cycle assessment suggest that the annual PV electric output efficiencies can increase up to 35%, and the annual total system energy efficiency including electric output and hot water energy output can increase up to 107%. The cost payback time can be reduced to 12.1 years, compared to 15 years of the baseline of a similar system without cooling sub-system.
    • Design and study of a circular polarised conical-disc-backed spiral antenna for X-Band applications

      Ur-Rehman, Masood; Safdar, Ghazanfar Ali; Yang, Xiaodong; Chen, Xiaodong; University of Bedfordshire; Xidian University; Queen Mary University of London (IEEE, 2017-10-02)
      Design of a conical-disc-backed circular-polarized Archimedean single-arm spiral antenna is presented in this paper. The antenna operation covers the X -band frequencies ranging from 8 to 12 GHz. The antenna makes use of a very simple structure having the single-arm spiral backed by a cone-shaped metallic disc to achieve high gain, circular polarization, and unidirectional symmetric radiation near the boresight. The diameter of the antenna only measures to 40 mm. The simulated and measured results show that the antenna has a very good impedance matching (better than −10 dB), good right-hand circular polarization (with an axial ratio of ≤3 dB) throughout the frequency range of interest, and offers a maximum peak gain of 11.4 dBiC. The presented S11 response and radiation pattern results also show that the antenna offers excellent performance in the X -band with no need of a balun. Antenna usefulness is also established through a detailed parametric study and comparison with a traditional flat disc structure. Compact size, simple design, wide range, and high gain make the proposed antenna design a good choice for radar, terrestrial communications, and satellite/aerospace communications applications.
    • Determination of beam incidence conditions based on the analysis of laser interference patterns

      Wang, Dapeng; Wang, Zuobin; Yue, Yong; Yu, Juncai; Tan, Chunlei; Li, Dayou; Qiu, Renxi; Maple, Carsten; Changchun University of Science and Technology; University of Bedfordshire; et al. (Elsevier GmbH, 2015-11-01)
      Beam incidence conditions in the formation of two-, three- and four-beam laser interference patterns are presented and studied in this paper. In a laser interference lithography (LIL) process, it is of importance to determine and control beam incidence conditions based on the analysis of laser interference patterns for system calibration as any slight change of incident angles or intensities of beams will introduce significant variations of periods and contrasts of interference patterns. In this work, interference patterns were captured by a He-Ne laser interference system under different incidence conditions, the pattern period measurement was achieved by cross-correlation with, and the pattern contrast was calculated by image processing. Subsequently, the incident angles and intensities of beams were determined based on the analysis of spatial distributions of interfering beams. As a consequence, the relationship between the beam incidence conditions and interference patterns is revealed. The proposed method is useful for the calibration of LIL processes and for reverse engineering applications.
    • 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.