• 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)
      A polarisation diversity combing scheme for dual-polarised multiple-input and multiple-output channels in small cell environments introduced and evaluated. The scheme is based on post analysis of channel measurement data captured from scenarios and includes indoor-to-indoor, indoor-to-outdoor, and indoor-outdoor-indoor propagation. An analysis of link signal strength and correlation with respect to frequency and polarisation revealed profound differences between copolarised and cross-polarised links in terms of received signal strength and correlation between frequencies. Utilizing these differences, a polarisation diversity combing scheme is evaluated which is shown to produce an average of 10.6-dB polarisation diversity gain.
    • Analysis of the mechanical properties of chromosomes in air and liquid by AFM

      Wang, Bowei; Yang, Fan; Dong, Jianjun; Li, Jiani; Wang, Ying; Qu, Kaige; Wei, Huimiao; Wang, Zuobin; Changchun University of Science and Technology; Changli Nano Biotechnology Ltd; et al. (IEEE, 2021-11-18)
      Chromosomes contain all the genomic information thus making the study of chromosomes practical and significant. Herein, the morphologies of chromosomes prepared with different methods were monitored by atomic force microscopy (AFM). Moreover, the mechanical properties of chromosomes in air and liquid were investigated quantitatively through AFM-based force spectroscopy. The differences of chromosome morphologies and mechanical properties caused by sample preparations indicated that the chromosome characterization in liquid was more meaningful to reveal the physiological characteristics of chromosomes.
    • 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.
    • 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.
    • 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.
    • 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.
    • A dynamic feedback algorithm of AFM based on cell morphology changes

      Cheng, Can; Wang, Xinyue; Dong, Jianjun; Liu, Zimin; Wang, Zuobin; Changchun University of Science and Technology; University of Bedfordshire (IEEE, 2021-11-18)
      The atomic force microscope (AFM) used in biological research as a powerful tool has been for many years. However, the imaging of living cells is still a problem as the sample is too high and too soft to obtain their accurate morphologies. Especially in the high-speed scanning mode, AFM does not have enough judgments to make accurate measurements at the down part of the sample. In this study, we propose an improved control method to improve the image quality of living human colon cancer cells (SW480) especially in the down part during the scanning.
    • Effect of astragalus polysaccharides on cancer cells studied by AFM

      Lu, Zhengcheng; Wang, Zuobin; Li, Dayou; Zhu, Wenyu; Wang, Rui; Qu, Kaige; Yan, Jin; University of Bedfordshire; Changchun University of Science and Technology (IEEE, 2021-11-18)
      As a traditional Chinese medicine, astragalus and its products are used in cancer treatment aiming to reduce the side effects of chemotherapy. Cells are the most basic unit of living organisms, and AFM directly obtains information from living cells on the micro/nano scale. Therefore, the use of AFM to study the interaction between astragalus and cells is conducive to a full range of drug efficacy evaluation and provides a new way for drug development. In this paper, astragalus polysaccharides were extracted from astragalus, which were diluted into solutions of different concentrations. Combined with the MTT experiment, the effects of Astragalus polysaccharide on cancer cells and benign cells were studied by AFM.
    • Effect of SMMC-7721-derived exosomes on hepatocytes studied by AFM

      Ju, Tuoyu; Yang, Fan; Wang, Ying; Song, Zhengxun; Xu, Hongmei; Chen, Yujuan; Wang, Zuobin; Changchun University of Science and Technology; University of Bedfordshire (IEEE, 2021-11-18)
      Exosomes play an important role in the early diagnosis and development of hepatocellular carcinoma (HCC). In the past, researchers mainly studied the contents of exosomes and the biological mechanism on cells, but the changes of mechanical properties of cells caused by exosomes are not clear. In this study, the changes of mechanical properties of hepatocytes (L-02) co-cultured with exosomes (7721-exos) derived from HCC (SMMC-7721) with low metastatic ability were studied. The 7721-exos were able to promote the proliferation and rearrange the cytoskeleton of L-02 cells. The atomic force microscopy measurement results showed that the height was increased, the adhesion and the elastic modulus were reduced. The effect was concentration dependent. The changes of cell mechanical properties induced by exosomes were of great significance for further studying the mechanism of exosomes.
    • 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.
    • 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.
    • Fabrication of hierarchical Ti6Al4V structures by hydrothermal treatment and laser interference lithography with enhanced ice resistance

      Liu, Ri; Wu, Xiaoming; Cao, Liang; Liu, Dongdong; Sun, Baishun; Weng, Zhankun; Wang, Zuobin; Changchun University of Science and Technology; University of Bedfordshire (IEEE, 2021-11-18)
      Icing widely exists in aerospace, transportation and electric power communication, causing great safety risks to people's production and life. Inhibiting icing is of great significance in practical engineering applications, and thus, employing an economical and efficient anti-icing method is a research hotspot. In this work, an anti-icing structured surface was fabricated by combining direct laser interference lithography (DLIL) with hydrothermal treatment. A micro-pillar array structure on the tc4 substrate was easily fabricated by DLIL, and a layer of nano-grass structure on the micro-pillar array was grown by hydrothermal treatment. These hierarchically textured surfaces exhibited low-temperature-adaptive water repellency (150° at −10°C, which delayed the frozen time (DT∼1h) and dropped frozen temperature. The above conditions were analyzed from the angle of wettability and heat conduction, and the influence of structure and wettability on ice resistance was discussed.
    • Growth behavior of SHSY5Y cells on hybrid micro-pit and nano-pillar arrays

      Wu, Xiaomin; Li, Li; Liu, Ri; Weng, Zhankun; Wang, Zuobin; Changchun University of Science and Technology; University of Bedfordshire (IEEE, 2021-11-18)
      The directional arrangement and extension of cells is of great significance in the tissue engineering field. Great efforts have been made to study the effects of micro- or nano- structures on cell behaviors, but they are still poorly understood. In this work, hybrid micro/nano structures prepared by combining laser marking technology with metal assisted chemical etching (MACE) were introduced to study their effect on the growth behavior of SHSY5Y cells. It was found that the cells on the silicon micro-pit arrays (SiMP arrays, unetched substrate) were arranged orderly along the edge of the micro-pits, stretched and connected with each other, while the cells on the hybrid silicon micro-pit and silicon nano-pillar arrays (hybrid SiMP/SiNP arrays, etched substrates) were also arranged in an orderly manner with a relatively short cell stretch, but displayed a preference for independent growth. In addition, about 90% of cells showed a preference for growing on the area of nano-pillars (NPs), and only 10% of cells on the area of micro-pits (MPs) on the etched substrate. The results showed that the hybrid SiMP/SiNP arrays trapped cells and restricted the cell spreading. Thus, this approach is of great significance for the study of independent growth behavior of cells on the substrate in the field of single neuron research.
    • A hybrid approach for image super-resolution of light field images

      Farag, Saber; Velisavljević, Vladan; Aggoun, Amar (IEEE, 2017-09-22)
      Recent advances in camera technologies has led to the design of plenoptic cameras. This camera type can capture multiple images of the same scene using arrays of microlenses, where each microlens has a shifted location providing a separate view of the scene. Such a design results in a superior performance as compared to traditional cameras, enabling multi-view or multi-focal imaging captured in a single shot. However, currently available plenoptic cameras are limited in spatial resolution, which makes it difficult to use them in applications where sharpness or high resolution is key, such as the film industry. Our paper presents a novel light field hybrid super-resolution method that combines two classical super-resolution techniques for efficient application to plenoptic images. After this combination, we first segment the output hybrid super-resolution image into the objects of interest. Afterward, we apply sparse representation to super resolve the segmented image. This technique helps to improve the quality by decrease computations for light field images and extract significant features from the objects of interest. We demonstrate the gain achieved by the novel method as compared to the current relevant approaches in terms of both PSNR and SSIM for various enhanced spatial resolutions.
    • 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.
    • Investigation of oxyfuel combustion on engine performance and emissions in a DI diesel HCCI engine

      Mobasheri, Raouf; Izza, Nadia; Aitouche, Abdel; Peng, Jun; Bakir, Boualem (IEEE, 2020-01-09)
      Due to stronger environmental standard aims, the European Union (EU) has recently adopted more stringent limits for emissions from inland waterway vessels. The objective of “RIVER” project is to apply an oxyfuel combustion technology for diesel engines that eliminates NOx emissions, and captures and stores all carbon dioxide emissions in order to achieve zero-carbon and zero other pollutant emissions. As part of this project, a 3-D computational fluid dynamics model coupled with detailed chemical kinetics has been used to evaluate the influence of oxyfuel combustion on engine operating conditions and combustion characteristic in a high speed direct injection (HSDI) diesel engine under homogenous charge compression ignition (HCCI) mode. In this work, a reduced chemical n-heptane-n-butanol-PAH mechanism which consists 76 species and 349 reactions has been applied to simulate the combustion process. The mechanism has been initially validated by experiments under HCCI combustion mode and then, it has been used to examine the oxyfuel combustion using different diluent strategies over a range of air-fuel equivalence ratio (lambda). The simulation results indicate that increasing the inlet carbon dioxide concentration, as a diluent gas, under constant fueling rate does not bring any serious change to the amount of brake mean effective pressure (BMEP) in the relatively rich mixtures regions. However, by decreasing the fuel rate (higher lambda) the difference between different diluent strategies become more obvious as the minimum amount of BMEP is achieved when 83% of carbon dioxide is used. In addition, the results show a considerable reduction of PM emissions while the NOx emission have been completely eliminated using oxyfuel combustion.
    • Laser interference field induced re-distribution of Ag nanoparticle arrays

      Yue, Ming; Liu, Mengnan; Li, Li; Liang, Xiubo; Wang, Lu; Wang, Zuobin; Changchun University of Science and Technology; University of Bedfordshire (IEEE, 2021-11-18)
      The wide application of metal nanoparticle arrays has attracted much attention in the field of nanotechnology. Such as quantum dots, structural colors, sensors, metamaterials. In this work, we fabricated periodic micro-and nanostructures through the interference of two beams with the same frequency and vibration direction. By controlling the spot energy and light field energy distribution of Gaussian interference lithography, the various surface characteristics of Ag-Si material system (Ag@Si) are optimized, and the mass transfer brought by Oswald ripening is used to control the Rayleigh instability in the thermal dewetting process. To achieve the purpose of the periodic gradient Ag nanoparticle arrays (AgNPs) pattern can be controlled. The experimental results show that the periodic micro-and nanostructures can be obtained by optimizing the spot energy and the number of pulses.
    • A low profile antenna for millimetre-wave body-centric applications

      Ur-Rehman, Masood; Malik, Nabeel A.; Yang, Xiaodong; Abbasi, Qammer Hussain; Xidian University (IEEE, 2017-09-27)
      Millimetre-Wave frequencies are a front runner contender for the next generation body-centric wireless communications. In this paper, design of a very low profile antenna is presented for body-centric applications operating in the millimetre-wave frequency band centred at 60 GHz. The antenna has an overall size of 14£10.5£1.15 mm3 and is printed on a flexible printed circuit board. The performance of the antenna is evaluated in off-body, on-body and body-to-body communication scenarios using a realistic numerical phantom and verified through measurements. The antenna has a bandwidth of 9.8 GHz and offers a gain of 10.6 dBi in off-body (free space) configuration while 12.1 dBi in on-body configuration. It also acheives an efficiency of 74% in off-body and 63% in on-body scenario. The small and flexible structure of the antenna along with excellent impedance matching, broad bandwidth, high gain and good efficiency makes it a suitable candidate to attain simultaneous data transmission/reception at millimetre-wave frequencies for the 5G body-centric applications.
    • Multi-parameter AFM characterization of INS-1 cells

      Yang, Fan; Wang, Bowei; Wang, Jiajia; Chen, Yujuan; Wang, Zuobin; Changchun University of Science and Technology; University of Bedfordshire (IEEE, 2021-11-18)
      AFM-based single cell force spectroscopy has been employed wildly, while more work is needed for the mechanical detection of diabetes-related cells (INS-1 cells). In this study, a multi-parameter AFM characterization was performed to detect the mechanical properties of INS-1 cells in situ. High resolution topographies and concurrent mechanics were obtained by taking the advantage of the quantitatively imaging (QI) mode AFM. The analyses of force curves and force maps jointly presented the multiple parameters involved in the cell mechanics. The AFM force spectroscopy measurement provides full analysis and comprehensive understanding of cell mechanics.