• Self-assembly of DNA molecules in magnetic fields

      Gao, Mingyan; Hu, Jing; Wang, Jianfei; Liu, Mengnan; Zhu, Xiaona; Saeed, Sadaf; Hu, Cuihua; Song, Zhengxun; Xu, Hongmei; Wang, Zuobin; et al. (IOP Publishing, 2021-11-18)
      In this work, a rich variety of self-assembled DNA patterns were obtained in the magnetic field. Herein, atomic force microscopy (AFM) was utilized to investigate the effects of the concentration of DNA solution, intensity and direction of magnetic field and modification of mica surface by different cations on the self-assembly of DNA molecules. It was found that owning to the change of the DNA concentration, even under the same magnetic field, the DNA self-assembly results were different. The in situ test results showed that the DNA self-assembly in an magnetic field was more likely to occur in liquid phase than in gas phase. In addition, whether in a horizontal or vertical magnetic field, a single stretched dsDNA was obtained in a certain DNA concentration and magnetic field intensity. Besides, the modification of cations on the mica surface significantly increased the force between the DNA molecules and mica surface, and further changed the self-assembly of DNA molecules under the action of magnetic field.
    • Sensing fresh water contamination using UV fluorescence methods

      Okache, Julius; Haggett, Barry G.D.; Maytum, Robin; Mead, Andrew; Rawson, David M.; Ajmal, Tahmina; University of Bedfordshire (IEEE, 2016-01-07)
      Water quality monitoring requires characterization of a range of organic and inorganic components present within the sample. We present here initial findings in the design of a novel system to detect contaminants by characterizing their characteristic fluorescence fingerprints in a 3-dimensional excitation emission matrix. This is a proof of principle for a system that would then use principal component analysis to diagnose the individual contaminants present in real world samples. A high-resolution fluorescence spectrometer was used to characterize components and potential pollutants in water samples along with samples taken at two different times from the feed into a lake. Several types of fluorescent signals were observed including the commonly used UV `protein-like' fluorescence as well as humic-like or yellow substances fluorescence. Development of this method will lead to a technique that will allow rapid identification of possible contaminants in water samples.
    • Separate and combined effects of hydrogen and nitrogen additions on diesel engine combustion

      Mobasheri, Raouf; Seddiq, Mahdi; Peng, Zhijun; University of Ayatollah Ozma Boroujerdi; University of Bedfordshire (Elsevier, 2017-12-01)
      Shortage of non-renewable energies, increase in fossil fuel prices and stricter emissions regulations due to high NOx and soot emissions emitted from combustion of heavy diesel fuels by compression ignition engines, has led consumers to use renewable, cleaner and cheap fuels. An investigation has been computationally carried out to explore the influences of hydrogen and nitrogen addition on engine performance such as indicated power and indicated specific energy consumption and amounts of pollutant emissions like NOx, soot, and CO in an HSDI (High-Speed Direct Injection) diesel engine. Optimized sub-models, such as turbulence model, spray model, combustion model and emissions models have selected for the main CFD code. Meanwhile, HF (Homogeneity Factor) has been employed for analysing in-cylinder air-fuel mixing quality under various addition conditions. After validations with experimental data of diesel combustion with a single addition of 4% hydrogen and combined addition of 6% hydrogen + 6% nitrogen, investigations have conducted for modelling mixing and combustion processes with additions of hydrogen and nitrogen by ranges of 2% to 8% (v/v). Results showed that a single addition of H2 increased NOx and decreased CO and soot and improved ISEC and IP. In the case of nitrogen addition, NOx decreased, both CO and soot emission increased and ISEC and IP considerably ruined compared with NDC operation. Based on the results obtained for simultaneous addition of N2 (8% of v/v) and H2 (8% of v/v), NOx and soot emissions decreased by 11.5% and 42.5% respectively, and ISEC and IP improved 25.7% and 13%, respectively. But amount of CO emissions had an increase of 52% should be paid ncecessary attention as a main disadvantage.
    • Simulation study on implementation of oxy-fuel combustion for a practical GDI engine

      Li, Xiang; Peng, Zhijun; Ajmal, Tahmina; Rana, Khaqan-Jim; Aitouche, Abdel; Mobasheri, Raouf; Pei, Yiqiang; University of Bedfordshire; University of Lille; Tianjin University (SAE, 2021-04-06)
      As the impacts of global warming have become increasingly severe, Oxy-Fuel Combustion (OFC) has been widely considered as a promising solution to reduce Carbon Dioxide (CO2) for achieving net-zero emissions. In this study, a one-dimensional simulation was carried out to study the implementation of OFC technology on a practical turbocharged 4-cylinder Gasoline Direct Injection (GDI) engine with economical oxygen-fuel ratios and commercial gasoline. When the engine is converted from Conventional Air-fuel Combustion (CAC) mode to OFC mode, and the throttle opening, oxygen mass fraction, stoichiometric air-fuel ratio (lambda = 1) are kept constant, it was demonstrated that compared to CAC mode, θF gets a remarkable extension whereas θC is hardly affected. θF and θC are very sensitive to the ignition timing, and Brake Specific Fuel Consumption (BSFC) would benefit significantly from applying Maximum Brake Torque (MBT) ignition timing. However, the power still does not reach the target at low load. With oxygen fraction increasing from 23.3% to 32%, it was found that θF and θC remain largely steady at low load and would extend a few degrees at m-h load. BSFC respectively gets a reduction of 33 g/kWh and 8.9 g/kWh. Meanwhile, Brake Specific Oxygen Consumption (BSOC) increases 677.9 g/kWh and 363.9 g/kWh, leading to a considerable cost that should be weighed under OFC mode of practical applications.
    • Study on the conductivity of DNA molecules under magnetic fields

      Gao, Mingyan; Hu, Jing; Wang, Jianfei; Liu, Mengnan; Zhu, Xiaona; Tian, Liguo; Hu, Cuihua; Song, Zhengxun; Xu, Hongmei; Wang, Zuobin; et al. (IEEE, 2021-11-18)
      In this work, the conductivity of DNA molecules under the effect of magnetic fields was studied by conductive atomic force microscopy (C-AFM). It is found that the self-assembly images of 7.5 ng/μL DNA aqueous solution on the bare mica and Au layer surfaces are quite different, and the DNA molecules are obviously stretched on the Au layer surface and single stretched DNA strands were obtained. In addition, the conductivity of single stretched DNA molecules in the horizontal stable magnetic field (SMF) and high frequency electromagnetic field (HFEF) were investigated in detail. The results showed that the conductivity of DNA was weakened by the effect of magnetic field.
    • Sustainable μECM machining process: indicators and assessment

      Mortazavi, Mina; Ivanov, Atanas; Brunel University London (Elsevier, 2019-07-06)
      Sustainability assessment of a manufacturing process is not an easy task and requires knowledge from inside of the process physics or chemistry as well as the overall process performance considering the effectiveness of the process and specific applications. Sustainability assessment is with increasing demand among the manufacturing companies. At present sustainability is considered only among the traditional manufacturing techniques and non-traditional processes do not receive enough attention in spite of the increasing demand for their use. Additionally micro and nano non-traditional manufacturing processes are nearly not considered in the studies for sustainability; and micro electrochemical machining (μECM) was not an exemption either. μECM is one of the promising non-conventional machining processes but its expensive structure, complex nature of the electrochemical reaction and process dependency on operator experiences has kept it back at research level. Securing a place for a new manufacturing process has to be done by proving its sustainability in comparison to the other existing processes. In this work, the aim is to establish a framework for assessment of the μECM sustainability based on five dimensions of the sustainability in order to justify its use and the initial investment cost. Indicators and measures for the effectiveness of the process are suggested as well as machining performance parameters are discussed. Routes for optimizing machining parameters is also explored. Finally the full picture sustainability assessment is generated.
    • Tapping atomic force microscopy imaging at phase resonance

      Sun, Baishun; Xie, Chenchen; Qu, Kaige; Cao, Liang; Yan, Jin; Wang, Ying; Tian, Liguo; Zhang, Wenxiao; Wang, Zuobin; Changchun University of Science and Technology; et al. (IEEE, 2021-11-18)
      Tapping atomic force microscope (TM-AFM) can measure soft samples, which has the advantages of low loss and high resolution, and has been widely used in the characterization of soft micro-nano materials by atomic force microscope (AFM). The phase image in TM-AFM contains sample properties, and it is an important method to characterize the sample by TM-AFM. At present, researchers usually select the frequency near the first resonance peak of the probe to drive its vibration to carry out scanning imaging. However, the phase sensitivity near the first-order resonance of the probe is not high. Therefore, the phase image of TM-AFM is also less sensitive to characterize micro-nano materials. In order to improve the phase sensitivity of the probe, the probe working at the phase resonance peak was selected in this paper to improve the phase sensitivity of the probe vibration and the imaging quality of TM-AFM phase image. The experimental results show that the phase image of phase resonance-atomic force microscope (PR-AFM) can provide not only the surface information but also the structure information of the sample subsurface. PR-AFM can be applied for better characterization of micro and nano materials.
    • A tri-band implantable antenna for biotelemetry applications

      Malik, Nabeel A.; Ajmal, Tahmina; Sant, Paul; Ur-Rehman, Masood; University of Bedfordshire; University of Glasgow (Institute of Electrical and Electronics Engineers Inc., 2020-09-29)
      In this paper we propose a compact size rectangular implantable tri-band patch antenna for biotelemetry applications. Rogers RT6010 is used as substrate and superstrate material. The resonant frequency is further lowered by using a shorting pin which also reduces patch resistance. For excitation 50-ohm microstrip line is used. The antenna operates in MICS band (402405) MHz, ISM band (902-928) MHz and (2.4-2.48) GHz at 402 MHz, 915 MHz and 2.4 GHz. The gain of the antenna is 2.05 dBi, 2.67 dBi and 5.39 dBi with bandwidth of 120 MHz, 166 MHz and 190 MHz at relevant frequencies when simulated in a fat layer box. SAR values are within allowable limits. The simulated results show that the antenna is an excellent choice for implantable applications as it can be used for data transmission, wakeup signal and wireless power transfer by using three frequency bands.
    • Visual SLAM algorithms and their application for AR, mapping, localization and wayfinding

      Theodorou, Charalambos; Velisavljevic, Vladan; Dyo, Vladimir; Nonyelu, Fredi; ; University of Bedfordshire; Briteyellow (Elsevier, 2022-08-03)
      Visual simultaneous localization and mapping (vSLAM) algorithms use device camera to estimate agent’s position and reconstruct structures in an unknown environment. As an essential part of augmented reality (AR) experience, vSLAM enhances the real-world environment through the addition of virtual objects, based on localization (location) and environment structure (mapping). From both technical and historical perspectives, this paper categorizes and summarizes some of the most recent visual SLAM algorithms proposed in research communities, while also discussing their applications in augmented reality, mapping, navigation, and localization.
    • Visual SLAM for dynamic environments based on object detection and optical flow for dynamic object removal

      Theodorou, Charalambos; Velisavljevic, Vladan; Dyo, Vladimir; University of Bedfordshire; Briteyellow Ltd (MDPI, 2022-10-03)
      In dynamic indoor environments and for a Visual Simultaneous Localization and Mapping (vSLAM) system to operate, moving objects should be considered because they could affect the system’s visual odometer stability and it is position estimation accuracy. vSLAM can use feature points or a sequence of images as it is only source of input in order to perform localization while simultaneously creating a map of the environment. A vSLAM system based on ORB-SLAM3 and on YOLOR was proposed in this paper. The newly proposed system in combination with an object detection model (YOLOX) applied on extracted feature points is capable of achieving 2-4% better accuracy as compared to VPS-SLAM and DS-SLAM. Static feature points such as signs and benches were used to calculate the camera position and dynamic moving objects were eliminated by using the tracking thread. A specific custom personal dataset that includes indoor and outdoor RGB-D pictures of train stations including dynamic objects and high density of people, ground truth data, sequence data, video recording with the train stations and X, Y, Z data was used to validate and evaluate the proposed method. The results show that ORB-SLAM3 with YOLOR as object detection achieves 89.54% of accuracy in dynamic indoor environments compared to previous systems such as VPS-SLAM.
    • 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.
    • Wrinkle measurement in glass-carbon hybrid laminates comparing ultrasonic techniques: a case study

      Larrañaga-Valsero, Beatriz; Smith, Robert A.; Tayong-Boumda, Rostand; Fernández-López, Antonio; Güemes, Alfredo; Universidad Politécnica de Madrid; University of Bristol (Elsevier Ltd, 2018-08-15)
      Wrinkles, (also known as out-of-plane waviness) are, unfortunately, a common phenomenon that has caused some wind-turbine blades to unexpectedly fail in service. Being able to detect the wrinkles while in the factory will reduce the risk of catastrophic failure and characterising the wrinkles would minimise the repaired area, thus increasing the efficiency of the repair and the design. This work compares the effectiveness of three different ultrasound techniques for detecting and characterising out-of-plane wrinkles in the typical glass-carbon hybrid laminates that are used for wind-turbine blades. The tests samples were manufactured so that the laminates and the defects are representative of those used in the wind-turbine industry. Basic mechanical tests were performed to check the drop in mechanical properties due to wrinkling. The ideal probe frequency was determined as the resonance frequency of the plies using an analytical ultrasonic-propagation model. The three different ultrasound techniques used are: full-matrix capture (FMC) with the total focusing method (TFM), a commercial phased-array instrument and an immersion test with a raster-scanned single-element focused probe. When possible, severity parameters of the wrinkle were measured on the ultrasonic images and compared with the measurements of the actual sample in order to determine which method best characterises such wrinkles and which would be more appropriate to implement in an industrial environment. Not all of the techniques allowed full characterisation of out-of-plane waviness on the specimens. The FMC/TFM method gave better results whilst phased-array technology and single-element immersion testing presented more challenges. An additional enhancement to the TFM imaging was achieved using an Adapted-TFM method with an angle-dependent velocity correction.