• A review on recent developments of thermoelectric materials for room-temperature applications

      Solemaini, Zohreh; Zoras, Stamatis; Ceranic, Boris; Shahzad, Sally; Cui, YUANLONG; University of Derby; University of Sheffield (Elsevier, 2019-12-13)
      Wearable thermoelectric generators (TEGs) emerge as a viable renewable energy source, which directly convert the heat dissipated from human skin into electricity. Extensive reviews have been conducted on the efficiency of thermoelectric materials (TE) as the dominant element of TEGs. TE materials are categorised as inorganic, organic, and hybrid. Each of these reviews focused on either a specific type of TE materials, or on a certain specification (i.e. flexibility) of them. However, less attention has been paid to comprehensively review all these types without taking into account a certain specification. Therefore, the purpose of this paper is to summarize the progress and current state-of-the-art research on the three types of TE materials respecting their TE properties and efficiency at 300K, which is the operating temperature of wearable TEGs. Concerning the inorganic TE materials, the results show that Bi0.4-xSb1.6+xTe3 and Bi2Te2.7Se0.3 are the most optimal TE materials, which exhibit the greatest efficiencies at room temperature. In addition, it is remarkably more efficient to replace polymer based TE composites with carbon based TE composites in the organic and the hybrid types. In total, this comprehensive review paves the way for researchers to find out the most suitable TE materials at room temperatures.
    • Multiple geophysical techniques for investigation and monitoring of sobradinho landslide, Brazil

      Hussain, Yawar; Cardenas-Soto, Martin; Martino, Salvatore; Moreira, Cesar; Borges, Welitom; Hamza, Omar; Prado, Renato; Uagoda, Rogerio; Rodríguez-Rebolledo, Juan; Silva, Rafeal; et al. (MDPI AG, 2019-11-26)
      Geophysical methods have a varying degree of potential for detailed characterization of landslides and their dynamics. In this study, the application of four well-established seismic-based geophysical techniques, namely Ambient Noise Interferometry (ANI), Horizontal to Vertical Spectral Ratio (HVSR), Multi-Channel Analysis of Surface Waves (MASW) and Nanoseismic Monitoring (NM), were considered to examine their suitability for landslide characterization and monitoring the effect of seasonal variation on slope mass. Furthermore, other methods such as Ground Penetrating Radar (GPR) and DC Resistivity through Electrical Resistivity Tomography (ERT) were also used for comparison purpose. The advantages and limitations of these multiple techniques were exemplified by a case study conducted on Sobradinho landslide in Brazil. The study revealed that the geophysical characterization of the landslide using traditional techniques (i.e., GPR, ERT and MASW) were successful in (i) the differentiation between landslide debris and other Quaternary deposits, and (ii) the delineation of the landslide sliding surface. However, the innovative seismic based techniques, particularly ambient noise based (HVSR and ANI) and emitted seismic based (NM), were not very effective for the dynamic monitoring of landslide, which might be attributed to the short-time duration of the data acquisition campaigns. The HVSR was also unsuccessful in landslide site characterization i.e., identification of geometry and sliding surface. In particular, there was no clear evidence of the light seasonal variations, which could have been potentially detected from the physical parameters during the (short-time) ambient noise and microseismic acquisition campaigns. Nevertheless, the experienced integration of these geophysical techniques may provide a promising tool for future applications
    • The evolution of turbulence characteristics in the wake of a horizontal axis tidal stream turbine

      Ahmadi, Mohammad H.B.; Yang, Zhiyin; University of Derby (Elsevier BV, 2019-11-21)
      The evolution of turbulence characteristics downstream of a laboratory-scale three-bladed horizontal axis turbine is investigated in this study. Large eddy simulation (LES) coupled with the Actuator Line Modelling (ALM) is used to simulate the flow. The numerical results compare well against experimental data, which shows that the LES/ALM technique is a powerful tool for simulating tidal stream turbines. The present study aims to obtain a better understanding of the turbulence characteristics of flow in the turbine wake by removing deterministic velocity fluctuations stemmed from the turbine rotation. Large eddy simulation is able to provide high-resolution spatial and temporal information needed for this work. The filtering process helps to have a clearer view of the flow structures downstream by tracking the streamwise variations of turbulence intensity and turbulent kinetic energy and, reveals a transition zone started shortly behind the turbine with a peak in the turbulence intensity. This study introduces turbulence intensity and turbulent kinetic energy as quantitative criteria to split the turbine wake into distinct regions. This research shows that to investigate and explain the influence of different upstream and operation conditions on the flow characteristics in the turbine wake, a well understanding of flow characteristic changes in the transition zone is necessary.
    • Invoking humanism in modernity: architecture and spectacle in fascist Italy

      Tracada, Eleni; Temple, Nicholas; University of Derby; University of Huddersfield (Routledge, 2019-11-01)
      The influence of Fascism on intellectual, artistic and architectural developments in interwar Italy has been the subject of intense debate. This has given rise to contested views about the combined impact of modernism and historical precedents on Fascist ideology, the arguments often clouded by disputes concerning the patrimony of art in Italy and whether Fascism should cultivate its own distinctive aesthetic. 2 However, many of the leading voices of Italian cultural life during the Fascist regime refused to discriminate between different aesthetic choices, believing that “Italian cultural traditions precluded aesthetic regulation.” 3 The debate becomes most revealing when considered in the context of the origins of Fascism. The eminent Italian philosopher and historian Benedetto Croce believed, for example, that Fascism could be traced back almost exclusively to the futurist movement, both in its artistic aspirations and in political activism … in the resolution to go down to the piazza, to impose one’s own feelings, to shut the mouths of those who are dissenting, to be unafraid of commotions and riots; in the eagerness of the new, in the desire to break every tradition, in the exaltation of youth, which was proper to futurism.” 4
    • Separated boundary layer transition under pressure gradient in the presence of free-stream turbulence

      Li, Huajun; Yang, Zhiyin; University of Derby; University of Sussex (AIP Publishing, 2019-10-14)
      Large-eddy simulation (LES) has been carried out to investigate the transition process of a separated boundary layer on a flat plate. A streamwise pressure distribution is imposed to mimic the suction surface of a low-pressure turbine blade, and the free-stream turbulence intensity at the plate leading edge is 2.9%. A dynamic subgrid scale model is employed in the study, and the current LES results compare well with available experimental data and previous LES results. The transition process has been thoroughly analyzed, and streamwise streaky structures, known as the Klebanoff streaks, have been observed much further upstream of the separation. However, transition occurs in the separated shear layer and is caused by two mechanisms: streamwise streaks and the inviscid K-H instability. Analysis suggests that streamwise streaks play a dominant role in the transition process as those streaks severely disrupt and break up the K-H rolls once they are formed, leading to significant three-dimensional (3D) motions very rapidly. It is also demonstrated in the present study that the usual secondary instability stage under low free-stream turbulence intensity where coherent two-dimensional (2D) spanwise rolls get distorted gradually and eventually broken up into 3D structures has been bypassed.
    • State-of-the-art review of 3DPV technology: structures and models

      Cui, Yuanlong; Zhu, Jie; Stamatis, Zoras; Chen, Xiangjie; Bi, Haixia; Qiao, Yaning; Soleimani, Zohreh; University of Derby; University of Nottingham; China University of Mining and Technology (Elsevier, 2019-10-05)
      Increasing energy conversion efficiency from sunlight to power is one of the key solutions for the world’s energy shortage and greenhouse gas reduction, but the conventional flat photovoltaic module without sun tracking mechanism has the low sunlight energy collection ability. This paper presents the state-of-the-art three-dimensional photovoltaic (3DPV) technology with high photovoltaic energy conversion efficiency, which is able to absorb off-peak sunlight and reflected light more effectively, thereby it can generate more power. At first, this paper is to catalogue and critique different 3DPV structures and models, as well as assess their characteristics. Afterwards, the main influence factors on the 3DPV structures and models including shape, height and spacing of the solar cells, latitude of the installation, optimal device design and shadow cast, are reviewed. Finally, the challenges and future technological developments of 3DPV structures and models are highlighted. This study demonstrated that the 3DPV technology can increase the captured sunlight approximately 15–30% in comparison with the conventional flat PV technology.
    • Creep response of various solders used in soldering ball grid array (BGA) on printed circuit board (PCB)

      Depiver, Joshua Adeniyi; Mallik, Sabuj; Amalu, Emeka H; University of Derby (Newsroom Limited, 2019-10)
      In electronics packaging, solder joints play a critical role by providing electrical, thermal and mechanical connections between the package and the printed circuit board (PCB). As the joint is both miniature and brittle, it is the weakest part of the assembly and thus susceptible to untimely damage. This paper presents the creep response of solder joints in a ball grid array (BGA) soldered on a PCB subjected to isothermal ageing in one experiment and temperature cycling in another test. The ageing is simulated in an ANSYS package environment at -40, 25, 75 and 150℃ temperatures applied for 45 days. The thermal cycling profile started from 22℃ and cycled between -40℃ and 150℃ with 15 minutes dwell time at the lowest and highest temperatures. The solders used in the investigation are lead-based eutectic solder alloy and lead-free SAC305, SAC387, and SAC396 solders. The research seeks to qualify these solders against strain and strain energy response for improved reliability in operation. The results show that the lead-free SAC387 accumulated the maximum strain and thus strain energy while the lead-based eutectic solder is found to accrue the least amount of the quantities. Further results show the distribution of damage in the BGA solder bump. Based on the results, it is proposed that lead-free SAC396 is the best replacement of the lead-based eutectic solder in the drive for the achievement of comparable thermo-mechanical reliability of assembled BGA on PCB.
    • Synthesis and characterization of tungsten and barium co-doped La2Mo2O9 by sol-gel process for solid oxide fuel cells

      Shao, Lingbo; Ji, Dongdong; Yang, Jie; Xie, Jinsong; Yin, Qiyi; Le, Huirong; Hefei University; University of Derby (Elsevier, 2019-09-30)
      Herein, we demonstrate the synthesis of W and Ba co-doped La2Mo2O9 (LBMWO) nanocrystalline powder by a sol-gel process. In all the compositions have general formulae La1.9Ba0.1Mo2–xWxO8.95 (x = 0–0.40). The crystal structure, microstructure and conductivity of LBMWO were characterized by X-ray diffraction, scanning electron microscopy and electrical impedance spectroscopy. In addition, the thermal and decomposition properties of the LBMWO gel were analyzed by differential scanning calorimetry - thermogravimetric. The results reveal that all LBMWO powders calcined at 700 °C have a cubic structure; the average crystallite size is about 48 nm. The unit cell parameter of LBMWO powders increases with increase in W content. The as-synthesized nanocrystalline LBMWO samples exhibit excellent sinterability and a relatively lower sintering temperature of 900 °C. A high relative density of ∼96% is achieved after sintering at 900 °C which is in good agreement with the results of the SEM. Moreover, W and Ba co-doping suppresses the phase transition and effectively stabilizes the β-phase at low temperature. At the same time, La1.9Ba0.1Mo1.85W0.15O8.95 exhibits high ionic conductivity, 3.07 × 10−2 S/cm at 800 °C. It is therefore concluded that co-doping can improve the properties of La2Mo2O9 electrolytes.
    • Antibacterial properties of silver nanoparticles grown in situ and anchored to titanium dioxide nanotubes on titanium implant against Staphylococcus aureus

      Gunputh, Urvashi F.; Le, Huirong; Lawton, Kiruthika; Besinis, Alexandros; Tredwin, Christopher; Handy, Richard D.; University of Derby; Plymouth University (Taylor & Francis, 2019-09-30)
      Medical grade titanium alloy, Ti-6Al-4V, with TiO2 nanotubes (TiO2-NTs) grown on the surface and then decorated with silver nanoparticles (Ag NPs) is proposed to enhance the antimicrobial properties of the bone/dental implants. However, the decoration with Ag NPs is not consistent and there are concerns about the direct contact of Ag NPs with human tissue. The aim of this study was to achieve a more even coverage of Ag NPs on TiO2-NTs and determine their biocidal properties against Staphylococcus aureus, with and without a top coat of nano hydroxyapatite (nHA). The decoration with Ag NPs was optimised by adjusting the incubation time of the TiO2-NTs in a silver ammonia solution, and using biocompatible δ-gluconolactone as a reducing agent. The optimum incubation in silver ammonia was 7 min, and resulted in evenly distributed Ag NPs with an average diameter of 47.5 ± 1.7 nm attached to the surface of the nanotubes. The addition of nHA did not compromise the antimicrobial properties of the materials; high-resolution electron microscopy showed S. aureus did not grow on the composite with nHA and with >80% biocidal activity measured by the LIVE/DEAD assay, also limited lactate production. Dialysis experiment confirmed the stability of the coatings, and showed a slow release of dissolved silver (3.27 ± 0.15 μg/L over 24 h) through the top coat of nHA.
    • Value chain impacts of EU waste framework directive 2018/851 as a result of reporting substances of very high concern from 2021

      Takhar, Sukhraj; Liyanage, Kapila; College of Engineering and Technology, University of Derby; Assent Compliance, Canada (University of Cambridge, 2019-09-27)
      The EU Waste Framework Directive 2018/851 sets out requirements for producers and importers of products within the EEA, to report data on Substances of Very High Concern (SVHC) content within products into a new central European database to from 5th January 2021. The reporting requirements: (1) support chemical regulations that impose the need on industry to record the use of hazardous chemicals; (2) identification of products entering waste streams containing hazardous chemicals; (3) support circular economy initiatives within the EU. To meet these new reporting requirements industry will need to collect additional information from all supply chain actors, who as duty holders will also be required to report into the new EU SVHC database system. Failure to provide the required information may result in enforcement actions from the authorities, which could see products being restricted from the EEA. The new EU database system will be accessible to industry, regulators, NGOs and the general public. This paper explores the new requirements, together with feedback received from various stakeholders for collection of data and reporting into the new EU database system from 2021.
    • Geohazard assessment of landslides in south Brazil: Case study

      Hamza, Omar; De Vargas, Tiago; Boff, Fernando Eduardo; Hussain, Yawar; Sian Davies-Vollum, K.; University of Derby; Centro Universitário da Serra Gaúcha (FSG); University of Brasilia (Springer Science and Business Media LLC, 2019-09-10)
      Slope instability phenomena such as mudslides represent a major geohazard in Brazil, which has caused devastation in many states and affected the lives of people, particularly in self-built settlements on steep slopes. This paper presents and discusses slope stability issues encountered in Caxias do Sul in the State of Rio Grande do Sul, which exemplifies the existing situation of landslide risk assessment in southern Brazil. Local geology and ground conditions of the area in relation to slope instability were reviewed and gaps in information required for mitigating risk were identified, such as inadequate geotechnical information and lack of full inspection and continuous monitoring of active landslides. Although risk assessment has been developed for the city and regarded as a fundamental management tool in the mitigation of landslide hazards, the study showed that the risk assessment works are outdated and not effectively considered for the development of the city. With significant unplanned urban expansion (where houses have been self-built on very steep terrains without geotechnical assessment of the ground and slope conditions), new geohazard mapping is essentially required. Several key recommendations were provided for mitigating the destructive effect of landslides and improving their management in mountainous urban settings.
    • Understanding the implications of chemical regulations, circular economy and corporate social responsibility for product stewardship

      Takhar, Sukhraj; Liyanage, Kapila; University of Derby (IOS Press, 2019-09-10)
      Chemical regulations exist to limit and control the amount of hazardous chemical substances being used by industry to mitigate potential risks. Increasing awareness of diminishing natural resources, increasing pollution, and reducing the amounts of harmful waste, has led towards pressure on industry to change from the traditional linear economic model (closed-loop manufacturing), towards the adoption of the Circular Economy (CE) activities. Corporate Social Responsibility (CSR) extends the relationship between industry and society, defining strategy and communications. The speed at which chemical regulations, CE and CSR adoption takes place will depend on: (1) the speed at which natural resources become more depleted; (2) increasing awareness of the effects of chemical substances by regulators and consumers; (3) increasing numbers of chemical substances being regulated as hazardous, and; (4) increasing consumer and societal pressures for change. Product Stewardship (PS) can be viewed as: (1) involving a wide range of functional areas (design, manufacture, purchasing, sales, support); (2) identifying health and safety, and environmental impacts of product(s); (3) ensuring adequate measures are in place to understand, control or limit impact(s) against a product throughout its lifecycle. The aim of this paper is to focus on using a literature review. The conclusions from this paper will attempt to outline a framework for PS to align with CE and CSR.
    • Thematic analysis of the learning experience of joint honours students: their perception of teaching quality, value for money and employability

      Pigden, Louise; Jegede, Franc; University of Derby (Taylor and Francis, 2019-09-04)
      The focus of the research was students’ perceptions of whether joint honours degrees represented a sound student learning experience and led to good academic and employability outcomes. In this minority mode of study for the United Kingdom, students study two academic subjects, rather than the more usual single subject. The qualitative methodology followed was a thematic analysis of self-administered questionnaire data, collected from joint honours students at four English universities in the United Kingdom. The principal results were that the students experienced difficulties in fitting into the two communities of learning for their respective subjects; in being adequately supported; in disparities in teaching, learning and assessment between their two subjects, and in a high workload. The major conclusion was that although the students perceived their learning experiences to have value by virtue of having studied two subjects, a number of issues stymied their achieving the best learning experience possible.
    • Experimental data of bio self-healing concrete incubated in saturated natural soil

      Souid, Adam; Esaker, Mohamed; Elliott, David; Hamza, Omar; University of Derby (Elsevier, 2019-08-22)
      he provision of suitable incubation environments is vital for successful implementation of bio self-healing concrete (bio-concrete). We investigated the effect of soil incubation to examine if the self-healing process can be activated in comparison with the conventional incubation environment (water). The data was collected from laboratory-scale experiments conducted on mortar specimens. The mortar was impregnated with Bacillus subtilis and this bacteria was encapsulated in calcium alginate for protection from the production process. The mortar specimens were mechanically cracked and then incubated within fine-grained fully saturated natural soil for about 4 weeks. The cracks were inspected before and after incubation by light microscopy to evaluate the healing ratio. The mineral precipitations on crack surfaces were examined by Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectrometry (EDX). The data reflects the efficiency of bio-concrete for certain structures such as tunnels and deep foundation, where concrete elements are exposed to ground conditions.
    • Variation of molecular mean free path in confined geometries

      Xie, Jianfei; University of Edinburgh (AIP Publishing, 2019-08-05)
      This paper aims to settle disputes in the literature about the spatial variation of the molecular mean free path (MFP) in confined geometries. The MFP of a gas is determined by using both molecular dynamics (MD) and the direct simulation Monte Carlo (DSMC) technique. In spatially-homogeneous cases, the numerical results exactly recover the kinetic theory predictions of a constant MFP. However, in microchannels, the MFP is found to vary near to the bounding walls and reduce at the surfaces to half of its bulk value as long as collisions between gas molecules and wall atoms are taken into account in the calculation of the MFP.
    • Effective mean free path and viscosity of confined gases

      Xie, Jianfei; University of Derby; University of Edinburgh; University of Strathclyde; University of Warwick (AIP Publishing, 2019-07-16)
      The molecular mean free path (MFP) of gases in confined geometries is numerically evaluated by means of the direct simulation Monte Carlo method and molecular dynamics simulations. Our results show that if calculations take into account not only intermolecular interactions between gas molecules but also collisions between gas molecules and wall atoms, then a space-dependent MFP is obtained. The latter, in turn, permits one to define an effective viscosity of confined gases that also varies spatially. Both the gas MFP and viscosity variation in surface-confined systems have been questioned in the past. In this work, we demonstrate that this effective viscosity derived from our MFP calculations is consistent with those deduced from the linear-response relationship between the shear stress and strain rate using independent nonequilibrium Couette-style simulations as well as the equilibrium Green-Kubo predictions.
    • Effects of the graphene nanoplatelets reinforced interphase on mechanical properties of carbon fibre reinforced polymer – A multiscale modelling study

      Le, Huirong; Lu, Yiling; Pawlik, Marzena; University of Derby (Elsevier, 2019-07-05)
      Mechanical properties of carbon fibre reinforced polymer (CFRP) are greatly affected by an interphase between fibre and matrix. Coating fibre with nanofillers has been suggested to improve the interphase properties. In this paper, a multiscale modelling framework was developed to investigate how graphene nanoplatelets (GnPs) influence the mechanical properties of CFRP laminate by reinforcing the interphase. At the nanoscale, the Mori-Tanaka homogenisation method was used to determine effective properties of the GnPs reinforced interphase. GnPs reinforced interphase properties at different GnPs orientations, and volume fractions were examined. At the microscale, a 3-D representative volume element (RVE) model based on obtained interphase properties was used to predict the elastic constants of CFRP unidirectional lamina. This RVE model consisted of three phases: carbon fibre, epoxy resin and the GnPs reinforced interphase. The incorporation of GnPs in the interphase increased both longitudinal and transverse lamina moduli. Finally, simulations of the three-point bending test were performed on the macroscale CFRP laminate. The macroscale modelling based on predicted lamina properties was found to reproduce experimentally measured flexural modulus well. It was found that the GnPs coating on fibre has a positive influence on the mechanical properties of CFRP, and the enhancement varied with orientation and local volume fraction of GnPs. In the presence of GnPs coating, 0° and 90° flexural moduli of CFRP laminate increased by 6.1% and 28.3% respectively.
    • Setting a framework for organisational sustainable development

      Liyanage, Kapila; Bastas, Ali; University of Derby (Elsevier, 2019-07-02)
      Increasing worldwide demand for products and services is applying a significant pressure on firms and supply chains operationally and financially, along with negative implications on our planet and the public. New perspectives and approaches are required to be adopted by all members of the society, including the businesses for sustainable development. However, enabling such integration from an organisational management perspective is not straightforward, due to complexities and conflicts associated with balanced integration of economic, environmental and social agendas. Aimed towards addressing this important industrial and societal research requirement, a tailored framework is presented, constructed upon the deeply rooted management principles of quality management (QM)and supply chain management (SCM) to facilitate integration of triple bottom line sustainability into business management. The framework outlines the practical steps for implementation of such an approach, including the quantitative, current state maturity assessment as one of the key application steps. This approach is taken forward to an application step, at an organisation in Cyprus, undertaken through the action research study method that enabled demonstrating both its application, and its positive effects on the sustainable development of the participating organisation. Several contributions are made, including the formulation of a practical approach to organisational integration of triple bottom line sustainability through QM and SCM. Particularly, a new management perspective was introduced with implications to many organisational managers that adopt ISO 9001 and supply chain integration principles, setting a framework for extending these principles beyond their original QM and SCM agendas towards organisational sustainable development.
    • The impacts of sustainability, extended producer responsibility and the circular economy on product pricing models

      Takhar, Sukhraj; Liyanage, Kapila; Department of Mechanical Engineering & the Built Environment (Gupta Publications, 2019-07)
      This paper examines product pricing in relation to Sustainability, Extended Producer Responsibility and the Circular Economy. Traditional linear economic systems focus on the use of mass production techniques to achieve the most competitively priced products on the marketplace. This in turn requires a large volume of resources to be consumed. The linear economic system is based on a closed loop system, where resources are used in product manufacture, and then used consumed by end user(s), to finally becoming waste products. Increasing consumption of natural resources, led to the evolution of (1) sustainability measures aimed at ensuring producers utilized more sustainable resources; (2) extended producer responsibility (EPR) schemes which placed burdens on producers to bear an economic cost for recovery and recycling activities for products they manufactured, and; (3) the circular economy, which sees producers encouraged to design products which use resources which are capable of being used by the r-imperatives. The results show implementing sustainability, EPR and the circular economy measures do impact costs and product prices.
    • Mechanical properties and tribological behaviour of electroless Ni–P–Cu coatings on corrosion-resistant alloys under ultrahigh contact stress with sprayed nanoparticles.

      Leech, Andrew; Le, Huirong; Meng, Maozhou; University of Derby; Plymouth University (Elsevier, 2019-06-20)
      Threaded components manufactured from corrosion resistant alloys (CRA's) are vulnerable to galling. This paper develops a test matrix to systematically investigate the mechanical properties and tribological performance of electroless nickel phosphorous coatings on CRA's when subjected to high contact stress. Samples manufactured from 28Cr stainless steel were shot-peened for various periods prior to being electo/electroless coated. The coefficient of friction (CoF) of different coating systems was evaluated via sliding cross-pin method. Various wet and dry lubricants were utilised to examine tribological performance, furthermore the adhesion strength of the coatings was investigated by a bond and pull-off method. The study has shown a significant reduction in CoF for electroless nickel phosphorous coatings with prior shot-peening treatment and sprayed nanoparticles.