• 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
    • Energy management in LTE networks

      Kanwal, Kapil; Safdar, Ghazanfar Ali; Ur-Rehman, Masood; Yang, Xiaodong; University of Bedfordshire (IEEE, 2017-03-28)
      Wireless cellular networks have seen dramatic growth in number of mobile users. As a result, data requirements, and hence the base-station power consumption has increased significantly. It in turn adds to the operational expenditures and also causes global warming. The base station power consumption in long-term evolution (LTE) has, therefore, become a major challenge for vendors to stay green and profitable in competitive cellular industry. It necessitates novel methods to devise energy efficient communication in LTE. Importance of the topic has attracted huge research interestsworldwide. Energy saving (ES) approaches proposed in the literature can be broadly classied in categories of energy efcient resource allocation, load balancing, carrier aggregation, and bandwidth expansion. Each of these methods has its own pros and cons leading to a tradeoff between ES and other performance metrics resulting into open research questions. This paper discusses various ES techniques for the LTE systems and critically analyses their usability through a comprehensive comparative study.
    • 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.
    • 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)
    • Fuzzy logic based intention recognition in STS processes

      Lu, Hang; Li, Dayou; Qiu, Renxi; University of Bedfordshire (Institute of Electrical and Electronics Engineers Inc., 2017-01-19)
      This paper represents a fuzzy logic based classifier that is able to recognise human users' intention of standing up from their behaviours in terms of the force they apply to the ground. The research reported focused on the selection of meaningful input data to the classifier and on the determination of fuzzy sets that best represent the intention information hidden in the force data. The classifier is a component of a robot chair which provides the users with assistance to stand up based on the recognised intention by the classifier.
    • 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
    • Optical based noninvasive glucose monitoring sensor prototype

      Haxha, Shyqyri; Jhoja, Jaspreet; University of Bedfordshire (IEEE, 2016-12-13)
      Diabetes mellitus claims millions of lives every year. It affects the body in various ways by leading to many serious illnesses and premature mortality. Heart and kidney diseases, which are caused by diabetes, are increasing at an alarming rate. In this paper, we report a study of a noninvasive measurement technique to determine the glucose levels in the human body. Current existing methods to quantify the glucose level in the blood are predominantly invasive that involve taking the blood samples using finger pricking. In this paper, we report a spectroscopy-based noninvasive glucose monitoring system to measure glucose concentration. Near-infrared transmission spectroscopy is used and in vitro experiments are conducted, as well as in vivo. Our experimental study confirms a correlation between the sensor output voltage and glucose concentration levels. We report a low-cost prototype of spectroscopy-based noninvasive glucose monitoring system that demonstrates promising results in vitro and establishes a relationship between the optical signals and the changing levels of blood–glucose concentration.
    • Optimisation of dispersion compensating in a long-haul fibre for RF transmission of up to 100Gbit/s by using RZ and NRZ formats

      Paloi, Fadil; Mirza, Taimur; Haxha, Shyqyri; University of Bedfordshire (Elsevier, 2016-12-02)
      With the recent data rate increase it is very challenging to build a fibre optic network that would enable a high data rate transmission over a long haul distance. The signal suffers large degradation over a certain distance due to distortion by the nonlinear effects of the optical fibres. In particular, transmission of high data rates over existing fibre optic systems, while keeping the cost low, avoiding an increase of the system’s complexity and the usage of expensive devices, would be a very challenging task. In this paper, we address this problem by increasing the transmission distance in the fibre optic links for up to 2500km. We have used Standard Single Mode Fibre (SSMF) and Dispersion Compensation Fibre (DCF), where DCF is used as a loss compensator in Radio-Over-Fibre (RoF) systems. A mixture combination of the pre, post and symmetrical fibre compensation schemes were developed to overcome the dispersion in the fibre. We have found that in order to achieve high RF over fibre optic system performance for high data rates and long transmission, there is a requirement to upgrade the optical configuration scheme in a proportional way, by raising the length of the fibre span, compensation span and amplification. We have reported optimised RF over fibre configuration schemes that would have a great impact on reducing the cost, reducing the system’s complexity and avoiding usage of expensive devices, in order to achieve high data rate transmission over existing fibre optic systems.
    • Minimal mean-square error for 3D MIMO beamforming weighting

      Xu, C.; Cosmas, John; Zhang, Yue; Brunel University; University of Bedfordshire (Institution of Engineering and Technology, 2016-11-24)
      The 3D MIMO beamforming system needs a weighting method to determine the direction of beam whist reducing the interference for other beam areas operating at the same carrier frequency. The challenge is to determine the weights of the 3D MIMO beams to direct each beam towards its cluster of user terminals while placing its nulls at undesired user directions to minimise undesired interference. Therefore, the signal-to-interference-plus-noise ratio should be increased while the interference from the side lobes of the other beams reduced. A weight determining method is presented that constructs horizontal and vertical array weights, respectively, by minimising the mean-square error between the array pattern vector and the unit vector, where the unit vector expresses the desired direction for the array pattern and zero vector expresses the undesired direction. Since the rectangular planar array can be viewed as M linear arrays of N elements, the weight of the M–Nth element can be obtained based on the horizontal and vertical array weights.
    • Wireless magnetic sensor network for road traffic monitoring and vehicle classification

      Velisavljević, Vladan; Cano, Eduardo; Dyo, Vladimir; Allen, Ben; University of Bedfordshire; European Commission, Joint Research Centre; University of Oxford (De Gruyter Open, 2016-11-23)
      Efficiency of transportation of people and goods is playing a vital role in economic growth. A key component for enabling effective planning of transportation networks is the deployment and operation of autonomous monitoring and traffic analysis tools. For that reason, such systems have been developed to register and classify road traffic usage. In this paper, we propose a novel system for road traffic monitoring and classification based on highly energy efficient wireless magnetic sensor networks. We develop novel algorithms for vehicle speed and length estimation and vehicle classification that use multiple magnetic sensors. We also demonstrate that, using such a low-cost system with simplified installation and maintenance compared to current solutions, it is possible to achieve highly accurate estimation and a high rate of positive vehicle classification.
    • Interference mitigation in D2D communication underlaying LTE-A network

      Safdar, Ghazanfar Ali; Ur-Rehman, Masood; Muhammed, Mujahid; Imran, Muhammad Ali; Tafazolli, Rahim; University of Bedfordshire; Birmingham City University; University of Glasgow; University of Surrey (IEEE, 2016-10-25)
      The mobile data traffic has risen exponentially in recent days due to the emergence of data intensive applications, such as online gaming and video sharing. It is driving the telecommunication industry as well as the research community to come up with new paradigms that will support such high data rate requirements within the existing wireless access network, in an efficient and effective manner. To respond to this challenge, device-to-device (D2D) communication in cellular networks is viewed as a promising solution, which is expected to operate, either within the coverage area of the existing eNB and under the same cellular spectrum (in-band) or separate spectrum (out-band). D2D provides the opportunity for users located in close proximity of each other to communicate directly, without traversing data traffic through the eNB. It results in several transmission gains, such as improved throughput, energy gain, hop gain, and reuse gain. However, integration of D2D communication in cellular systems at the same time introduces new technical challenges that need to be addressed. Containment of the interference among D2D nodes and cellular users is one of the major problems. D2D transmission radiates in all directions, generating undesirable interference to primary cellular users and other D2D users sharing the same radio resources resulting in severe performance degradation. Efficient interference mitigation schemes are a principal requirement in order to optimize the system performance. This paper presents a comprehensive review of the existing interference mitigation schemes present in the open literature. Based on the subjective and objective analysis of the work available to date, it is also envisaged that adopting a multi-antenna beamforming mechanism with power control, such that the transmit power is maximized toward the direction of the intended D2D receiver node and limited in all other directions will minimize the interference in the network. This could maximize the sum throughput and hence, guarantees the reliability of both the D2D and cellular connections.
    • 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.
    • 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.
    • Light-switching-light optical transistor based on metallic nanoparticle cross-chains geometry incorporating Kerr nonlinearity

      AbdelMalek, Fathi; Aroua, Walid; Haxha, Shyqyri; Flint, Ian; National Institute of Applied Science and Technology, Tunisia; University of Bedfordshire; 3Selex ES Ltd, Luton (Wiley-VCH Verlag, 2016-06-13)
      In this research work, we propose all-optical transistor based on metallic nanoparticle cross-chains geometry. The geometry of the proposed device consists of two silver nanoparticle chains arranged along the x- and z-axis. The x-chain contains a Kerr nonlinearity, the source beam is set at the left side of the later, while the control beam is located at the top side of the z-chain. The control beam can turn ON and OFF the light transmission of an incoming light. We report a theoretical model of a very small all-optical transistor proof-of-conceptmade of optical ‘light switching light’concept. We show that the transmission efficiency strongly depends on the control beam and polarization of the incoming light. We investigate the influence of a perfect reflector and reflecting substrate on the transmission of the optical signal when the control beam is turned ON and OFF. These new findings make our unique design a potential candidate for future highly-integrated optical information processing chips.
    • 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)
    • Pulse oximetry optical sensor using oxygenbound haemoglobin

      Cohen, Zachary Joel Valentino; Haxha, Shyqyri; Aggoun, Amar; University of Bedfordshire (Optical Society of America, 2016-05-02)
      In this paper we report a unique approach to measuring oxygen saturation levels by utilising the wavelength of the haemoglobin instead of the conventional absorption difference. Two experiments are set up to measure the wavelength of the haemoglobin bound to oxygen at different oxygen saturation levels with the help of a spectrometer. We report a unique low cost and robust wavelength monitoring SpO2 sensor that measures the SpO2 by using the colour of the blood and not the absorption difference of oxyhaemoglobin and deoxyhaemoglobin. With use of a spectrometer, we show that the wavelength of the oxygen-bound haemoglobin has a relation to the oxygen saturation level. The proposed device is designed and experimentally implemented with a colour sensor to measure the SpO2 level of the blood.
    • Highly birefringent nonlinear PCF for optical sensing of analytes in aqueous solutions

      Ademgil, Huseyin; Haxha, Shyqyri; European University of Lefke, Turkey; University of Bedfordshire (Elsevier, 2016-05-01)
      This paper presents a design of a nonlinear Photonic Crystal Fiber (PCF) based sensor exhibiting simultaneously high sensitivity, high birefringence and low confinement losses for liquid analyte sensing applications. We investigate the PCF sensor performance for the following analytes; Water, Ethanol and Benzyne. The impact of various design parameters of the highly nonlinear PCF on the relative sensitivity, the confinement losses and the birefringence features of the proposed PCF structure is numerically investigated by employing the full vectorial Finite Element Method (FEM). According to our FEM numerical results, a three ring nonlinear PCF based sensor is designed that simultaneously offers high birefringence of order 10-3 and high relative sensitivity at wide wavelength range.
    • Energy detection based spectrum sensing over two-wave and diffuse power fading channels

      Chatziantoniou, Eleftherios; Allen, Ben; Velisavljević, Vladan; Karadimas, Petros; Coon, Justin; University of Bedfordshire; Queens University Belfast; University of Oxford (IEEE, 2016-04-21)
      One of the most important factors that affects the performance of energy detection (ED) is the fading channel between the wireless nodes. This paper investigates the performance of ED-based spectrum sensing, for cognitive radio (CR), over two-wave with diffuse power (TWDP) fading channels. The TWDP fading model characterizes a variety of fading channels, including well-known canonical fading distributions, such as Rayleigh and Rician, as well as worse-than-Rayleigh fading conditions modeled by the two-ray fading model. Novel analytic expressions for the average probability of detection over TWDP fading that account for single-user and cooperative spectrum sensing and square law selection diversity reception are derived. These expressions are used to analyze the behavior of ED-based spectrum sensing over moderate, severe, and extreme fading conditions and to investigate the use of cooperation and diversity as a means of mitigating the fading effects. The obtained results indicate that TWDP fading conditions can significantly degrade sensing performance; however, it is shown that detection performance can be improved when cooperation and diversity are employed. The presented outcomes enable identifying the limits of ED-based spectrum sensing and quantifying the tradeoffs between detection performance and energy efficiency for CR systems deployed within confined environments, such as in-vehicular wireless networks.
    • 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.